,transcrib] ,note ,text emphasis d5ot$ by ,italics & ,bold4 ,:ole & fractional p>ts ( numb]s z #abc-d_/e4 ,,! ,,anci5t ,,volcanoes ,,( ,,great ,,brita9 ,illu/ration ,,! ,,anci5t ,,volcanoes ,,( ,,great ,,brita9 ,,by ,,sir ,,ar*ibald ,,geikie1 ,f4,r4,s4 ,d4,c4,l4 ,oxf41 ,d4,sc4 ,camb41 ,dubl42 ,,ll4,d4 ,/4 ,&4 ,ed9b4 ,,director-,,g5]al ,,( ,,! ,,geological ,,survey ,,( ,,great ,,brita9 ,,& ,,irel&2 ,,correspond5t ,,( ,,! ,,in/itute ,,( ,,france2 ,,( ,,! ,,academies ,,( ,,b]l91 ,,vi5na1 ,,muni*1 ,,tur91 ,,belgium1 ,,/ockholm1 ,g,,tt+51 ,,new ,,york2 ,,( ,,! ,,imp]ial ,,m9]alogical ,,society ,,& ,,society ,,( ,,naturali/s ,,/4 ,,pet]sburg2 ,,natural ,,hi/ory ,,society1 ,,mosc[2 ,,sci5tific ,,society1 ,,*ri/iania2 ,,am]ican ,,philosophical ,,society2 ,,( ,,! ,,geological ,,societies ,,( ,,london1 ,,france1 ,,belgium1 ,,/ockholm1 ,,etc4 ,,) ,,sev5 ,,maps ,,& ,,num]\s ,,illu/rations ,,9 ,,two ,,volumes ,,vol4 ,,ii ,london ,,macmillan ,,& ,,co41 ,limit$ ,,new ,,york3 ,,! ,,macmillan ,,company #ahig ,all rights res]v$ ,,cont5ts ,,*apt] ,,xxix ,! ,c>bonif]\s ,volcanoes ( ,engl& ,,page ,! ,nor? ( ,engl&3 ,dykes1 ,great ,:9 ,sill--,! ,d]by%ire ,toad/ones--,! ,isle ( ,man--,ea/ ,som]set--,devon%ire #a ,,*apt] ,,xxx ,! ,c>bonif]\s ,volcanoes ( ,irel& ,k+'s ,c\nty--,! ,lim]ick ,bas9--,! ,volcanic ,breccias ( ,d\btful ,age 9 ,c\nty ,cork #cg ,,book ,,vii ,,! ,,p]mian ,,volcanoes ,,*apt] ,,xxxi ,! ,p]mian ,volcanoes ( ,scotl& ,geographical ,*anges at ! ,close ( ! ,c>bonif]\s ,p]iod--,l& & ,inl&-,seas ( ,p]mian "t--,g5]al ,*>act]i/ics & ,nature ( ! ,mat]ials erupt$--,/ructure ( ! sev]al ,volcanic ,di/ricts3 #a4 ,ayr%ire1 ,ni?sdale1 ,ann&ale2 #b4 ,bas9 ( ! ,fir? ( ,=? #ec ,,*apt] ,,xxxii ,p]mian ,volcanoes ( ,engl& ,! ,devon%ire ,c5tre--,eruptive ,rocks ( ! ,midl& ,coal-fields #id ,,book ,,viii ,,! ,,volcanoes ,,( ,,t]ti>y ,,"t ,,*apt] ,,xxxiii ,va/ lapse ( "t betwe5 ! close ( ! ,palozoic & beg9n+ ( ! ,t]ti>y ,volcanic ,eruptions--,prolong$ ,volcanic ,quiesc5ce--,progress ( ,inve/igation among ! ,t]ti>y ,volcanic ,s]ies ( ,brita9 #ajg ,,*apt] ,,xxxiv ,! ,sy/em ( ,dykes 9 ! ,t]ti>y ,volcanic ,s]ies ,geographical ,di/ribution--,two ,types ( ,protrusion--,nature ( compon5t ,rocks--,hade--,bread?--,int]ruptions ( ,lat]al ,cont9uity--,l5g?--,p]si/5ce ( ,m9]al ,*>act]s #aah ,,*apt] ,,xxxv ,! ,sy/em ( ,dykes--cont9u$ ,direction--,t]m9ation upw>d--,kn[n v]tical ext5sion--,evid5ce z to ! movem5t ( ! ,molt5 ,rock 9 ! ,fissures--,bran*es & ,ve9s--,connection ( ,dykes ) ,intrusive ,%eets--,int]section ( ,dykes--,dykes ( m ?an "o infill+--,contact metamorphism ( ! ,dykes--,relation ( ! ,dykes to ! ,geological ,/ructure ( ! ,di/ricts :i* !y trav]se--,data = e/imat+ ! ,geological ,age ( ! ,dykes--,orig9 & ,hi/ory ( ! ,dykes #ade ,,*apt] ,,xxxvi ,! ,plateaux ,nature & ,arrangem5t ( ! ,rocks3 #a4 ,lavas4--,basalts1 ,dol]ites1 ,&esites--,/ructure ( ! ,lavas 9 ! ,field--#b4 ,fragm5tal ,rocks4--,agglom]ates1 ,conglom]ates1 & ,breccias--,tuffs & _! accompanim5ts #aha ,,*apt] ,,xxxvii ,! ,sev]al ,basalt-,plateaux & _! ,geological ,hi/ory--,antrim1 ,mull1 ,morv5 & ,ardnamur*an #aii ,,*apt] ,,xxxviii ,! ,basalt-,plateau ( ! ,p>i% ( ,small ,isles--,riv]s ( ! ,volcanic ,p]iod #bae ,,*apt] ,,xxxix ,! ,basalt-,plateaux ( ,skye & ( ! ,f>oe ,isles #bdi ,,*apt] ,,xl ,! ,mod]n ,volcanoes ( ,icel& z illu/rative ( ! ,t]ti>y ,volcanic ,hi/ory ( ,nor?-,we/]n ,europe #bfj ,,*apt] ,,xli ,! ,eruptive ,v5ts ( ! ,basalt-,plateaux ,v5ts fill$ ) ,basalt or o!r ,lava-=m ,rock--,v5ts fill$ ) ,agglom]ate #bgj ,,*apt] ,,xlii ,! ,basic ,sills ( ! ,basalt-,plateaux #bih ,,*apt] ,,xliii ,! ,bosses & ,%eets ( ,gabbro ,petrography ( ! ,rocks--,relations ( ! ,gabbros to ! o!r memb]s ( ! ,volcanic s]ies--,description ( ! ,gabbro di/ricts--,skye #cbg ,,*apt] ,,xliv ,! ,bosses & ,%eets ( ,gabbro 9 ! ,di/ricts ( ,rum1 ,ardnamur*an1 ,mull1 ,/4 ,kilda & ,nor?-,ea/ ,irel&4 ,hi/ory ( ! ,gabbro ,intrusions #cdi ,,*apt] ,,xlv ,! ,acid ,rocks ,_! ,petrography--,_! ,/ratigraphical ,position & its ,analogies 9 ,c5tral ,france #cfd ,,*apt] ,,xlvi ,types ( ,/ructure 9 ! ,acid ,rocks--,bosses #cgh ,,*apt] ,,xlvii ,! ,acid ,bosses ( ,mull1 ,small ,isles1 ,/4 ,kilda1 ,arran1 & ! ,nor?-,ea/ ( ,irel& #cie ,,*apt] ,,xlviii ,! ,acid ,sills1 ,dykes & ,ve9s #dcj ,,*apt] ,,xlix ,! ,subsid5ces & ,dislocations ( ! ,plateaux #ddg ,,*apt] ,l ,effects ( ,d5udation #dee ,,*apt] ,,li ,summ>y & ,g5]al ,d$uctions #dff ,,li/ ,,( ,,illu/rations ,,fig4 ,,page #agf4 ,section f ! great ,lime/one esc>pm5t on ! we/ to ! ,mill/one ,grit hills ea/ ( ,teesdale #d #agg4 ,sections ( ! ,c>bonif]\s ,lime/one s]ies ( ,nor?umb]l& %[+ ! v>iations 9 ! position ( ! ,:9 ,sill4 ,by ,messrs4 ,topley & ,leb\r #f #agh4 ,view ( two volcanic necks 9 ! ,c>bonif]\s ,lime/one s]ies1 at ,grange ,mill1 five miles we/ ( ,matlock ,ba?1 f ! nor? #ad #agi4 ,plan ( necks & b$d$ tuff at ,grange ,mill1 five miles we/ ( ,matlock ,ba? #ae #ahj4 ,section across ! small] volcanic neck & ! /ratifi$ tuff 9 ,c>bonif]\s ,lime/one1 ,grange ,mill #ae #aha4 ,section ( vesicul> & amygdaloidal diabase re/+ on ,c>bonif]\s ,lime/one1 ,peak ,=e/ ,limeworks1 ,great ,rocks ,qu>ry #ai #ahb4 ,view ( ! sup]position ( ,c>bonif]\s ,lime/one ^u toad/one1 ,rav5's ,tor1 ,mill]sdale 7l5g? ab\t #ajj feet7 #ai #ahc4 ,section at lime-kiln1 s\? ( ,viaduct1 ,mill]sdale ,/ation #bj #ahd4 ,lime/ones pass+ "u /ratifi$ tuffs1 ,poyll ,vaai%1 ,isle ( ,man #bd #ahe4 ,section ( tuff1 %[+ int]calations ( black impure *]t1 we/ ( ,clos5y*ollagh ,po9t1 ne> ,ca/let[n1 ,isle ( ,man #be #ahf4 ,section ( int]calat$ d>k lime/one1 %ale & *]t 9 ! tuff s\? ( ,poyll ,vaai% ,bay1 ,isle ( ,man #bf #ahg4 ,section ( "p ( a volcanic neck on %ore to ! s\?-ea/ ( ,poyll ,vaai% ,bay1 ,isle ( ,man #bi #ahh4 ,section ( successive dis*>ges & di/urbances )9 a volcanic v5t4 ,sc>let ,po9t1 ,isle ( ,man #bi #ahi4 ,section ( dyke & sill 9 ! tuffs we/ ( ,sc>let ,po9t1 ,isle ( ,man #cj #aij4 ,section on s\? side ( vesicul> sill we/ ( ,sc>let ,po9t #ca #aia4 ,b&s ( vesicles 9 ! same sill #ca #aib4 ,croghan ,hill1 ,k+'s ,c\nty1 f ,s4,s4,w4 #ch #aic4 ,section 9 qu>ry on roadside ea/ ( ,lim]ick1 close to viaduct ( ! ,lim]ick & ,erris ,railway #dd #aid4 ,section ( ! volcanic esc>pm5t1 ea/ ( ,%ehan's ,cross-roads1 s\? ( ,lim]ick #de #aie4 ,view ( ,d]k ,hill1 a volcanic neck on ! s\? side ( ! ,lim]ick bas9 #dg #aif4 ,section across ! ,lim]ick volcanic bas9 #dh #aig4 ,section ( a b$ ( volcanic breccia 9 ! ,c>bonif]\s ,slate2 ,:ite ,bull ,head1 ,c\nty ,cork #ej #aih4 ,volcanic breccia invad+ & enclos+ ,c>bonif]\s slate1 ,:ite ,bull ,head #ej #aii4 ,g5]al section across ! ,p]mian bas9 ( ,ayr%ire #ei #bjj4 ,section ( lavas1 ea/ side ( ,mau*l9e ,hill #fj #bja4 ,section ( ! top ( ! volcanic s]ies ne> ,ea/side ,cottage1 ,c>ron ,wat]1 ,ni?sdale #fj #bjb4 ,section ( two outli]s ( ! ,p]mian volcanic s]ies at ! foot ( ,w9dyhill ,burn1 ,wat] ( ,ae1 ,dumfries%ire #fa #bjc4 ,! ,gre5 ,hill1 ,wat]side1 ,dalmell+ton1 f ! s\?2 a tuff-neck ( ,p]mian age #fb #bjd4 ,patna ,hill f ! ,doon ,bridge1 ,ayr%ire2 a tuff-neck ( ,p]mian age #fc #bje4 ,gr\nd plans ( ,p]mian volcanic v5ts f ! ,ayr%ire ,coal-field4 ,on ! scale ( six in*es to a mile #fd #bjf4 ,section ( sills trav]s+ ! ,p]mian volcanic s]ies4 ,riv] ,ayr1 ,ballo*myle #ff #bjg4 ,section %[+ ! relations ( ! lat] rocks ( ,ar?ur ,seat #fh #bjh4 ,section 9 brooks betwe5 ,bonny t[n & ,balda/>d1 ,l>go #gj #bji4 ,view ( ,l>go ,law f ! ea/ #ga #baj4 ,view ( small neck 9 ,calcif]\s ,s&/ones1 on ! %ore1 ?ree miles ea/ f ,/4 ,&rews #gb #baa4 ,gr\nd-plan ( ,p]mian volcanic v5ts #gc #bab4 ,small neck 9 ,calcif]\s ,s&/ones a little ea/ f ! ,rock & ,sp9dle1 two & a half miles ea/ f ,/4 ,&rews #gd #bac4 ,plan ( volcanic necks at ,kellie ,law1 ,ea/ ( ,fife1 on ! scale ( ?ree in*es to "o mile #ge #bad4 ,plan ( ! crat]s 9 ,volcanello1 ,lip>i ,isl&s #ge #bae4 ,section ( ! /rata at ! edge ( ! volcanic v5t on ! ea/ side ( ,elie ,h>b\r #gf #baf4 ,agglom]ate ( neck on %ore at ,ardross1 two miles ea/ f ,elie #gg #bag4 ,gr\nd-plan ( volcanic neck1 ,elie ,h>b\r1 %[+ circul> disposition ( ! /ratification #hj #bah4 ,section across ! great v5t ( ,k9craig1 ,elie1 on a true scale1 v]tical & horizontal1 ( six in*es to a mile #ha #bai4 ,dyke 9 volcanic neck1 on ! bea*1 ,/4 ,monans #hb #bbj4 ,section ( "p ( crat] rim1 ,isl& ( ,volcano #hc #bba4 ,dyke ris+ ?r\gh ! agglom]ate ( a volcanic v5t2 ,k9craig1 ,elie #hd #bbb4 ,radiat+ column> dyke 9 ! tuff ( a volcanic v5t4 ,rock & ,sp9dle1 two & a half miles ea/ f ,/4 ,&rews #hf #bbc4 ,view ( "p ( ! %ore front ( ! great v5t at ,k9craig1 look+ we/w>d1 ) ! column> basalt 9 front #hh #bbd4 ,plan ( volcanic neck on bea* ne> ,/4 ,monans #hi #bbe4 ,column> basalt 9 ! neck ( ,k9craig1 ,elie1 se5 f ! we/ #ij #bbf4 ,section across ,l>go ,law #ia #bbg4 ,ve9 ( :ite-trap cutt+ black c>bonace\s %ales1 a little we/ f ,/4 ,monans ,*ur* #ib #bbh4 ,section at ,belv$]e1 ,s4 ,w4 ( ,exet] #ig #bbi4 ,diagram to %[ ! uncon=mability & ov]lap ( ! ,p]mian rocks 9 ! ,cr$iton ,valley #ig #bcj4 ,section ( ! volcanic s]ies at ,kell]ton1 ,devon%ire #ih #bca4 ,section ( agglom]ate ov]la9 ) s&/one & &esite1 ,posbury1 ,cr$iton #ii #bcb4 ,diagrammatic section across ,titt]/one ,clee ,hill #ajb #bcc4 ,dyke on ! s\?-ea/ coa/ ( ! ,isl& ( ,mull #aai #bcd4 ,fissure left by ! wea!r+ out ( a dyke #abj #bce4 ,plan ( basalt-ve9s ) selvages ( black basalt-glass1 ea/ side ( ,be9n ,tighe1 ,isle ( ,eigg #abf #bcf4 ,arrangem5t ( l9es ( amygdales 9 a dyke1 ,/ra?more1 ,skye #acj #bcg4 ,sy/ems ( jo9ts 9 ! dykes #acb #bch4 ,section ( cyl9drical ve9 or dyke1 cutt+ ! b$d$ lavas1 ea/ side ( ,fugl1 ,f>oe ,isl&s #acc #bci4 ,jo9t-/ructures 9 ! c5tral vitre\s portion ( ! ,eskdale ,dyke 7,b4 ,n4 ,pea*7 #acc #bdj4 ,microscopic /ructure ( ! vitre\s "p ( ! ,eskdale ,dyke #acf #bda4 ,section along ! l9e ( ! ,clevel& ,dyke at ,cliff ,ridge1 ,guisbr\gh 7,g4 ,b>r[71 scale1 #ab in*es to #a mile #adg #bdb4 ,section along ! c\rse ( ! ,clevel& ,dyke1 at ! head ( ,lonsdale1 ,york%ire 7,g4 ,b>r[1 9 ! ,memoirs ( ! ,geol4 ,survey1 ,geology ( ,clevel&1 p4 #fa7 #adh #bdc4 ,section across ! extreme upp] limit ( ,clevel& ,dyke1 on ! scale ( #bj feet to "o in* 7,mr4 ,g4 ,b>r[7 #adi #bdd4 ,upp] limit ( ,clevel& ,dyke 9 qu>ry ne> ,cockfield 7aft] ,mr4 ,teall7 #adi #bde4 ,section along ! c\rse ( ! ,clevel& ,dyke across ! ,cross ,fell esc>pm5t 7scale ( "o in* to "o mile7 #aej #bdf4 ,bran*+ portion ( ! great dyke ne> ,hawick 7l5g? ab\t "o mile7 #aec #bdg4 ,bran*+ dyke at foot ( ,gl5 ,artney 7l5g? ab\t f\r miles7 #aec #bdh4 ,basic ve9s trav]s+ ,second>y lime/one & s&/one on ! coa/ cliffs1 ,aidnamur*an #aee #bdi4 ,section %[+ ! connection ( a ,dyke ) an ,intrusive ,%eet1 ,po9t ( ,suisni%1 ,skye #aef #bej4 ,section to %[ ! connection ( a ,dyke ) an ,intrusive ,%eet1 ,/irl+%ire ,coal-field #aeg #bea4 ,int]section ( dykes 9 b$d$ basalt1 ,callia* ,po9t1 ,mull #aeh #beb4 ,basalt ve9s trav]s+ b$d$ dol]ites1 ,kildonan1 ,eigg #aei #bec4 ,gr\nd-plan ( int]sect+ dykes 9 ,lias lime/one1 ,%ore1 ,h>rabol1 ,ea/ ( ,broad=d1 ,skye #aei #bed4 ,comp\nd dyke1 ,m>ket ,/ance1 ,broad=d1 ,skye #afb #bee4 ,section ( coal r5d]$ column> by intrusive basalt1 %ore1 ,saltcoats1 ,ayr%ire #afd #bef4 ,dol]ite dyke ) m>g9al b&s ( :ite trap1 9 black %ale1 ,l[] ,lias1 ,pabba #aff #beg4 ,map ( ! *ief dykes betwe5 ,lo*s ,ridd5 & ,/riv5 7,c4 ,t4 ,cl\gh1 ,geological ,survey1 ,%eet #bi7 #agj #beh4 ,basalt-ve9s trav]s+ granophyre1 ,/4 ,kilda #agc #bei4 ,section ( scoriace\s & prismatic basalt1 ,camas ,?>b]ni%1 nor? %ore ( ,canna ,isl& #ahg #bfj4 ,b&$ amygdaloidal basalt %[+ lay]s ( elongat$ & /eeply incl9$ vesicles1 ,macleod's ,maid5s1 ,skye #aia #bfa4 ,t]m9ation ( basalt-b$s1 ,c>saig1 ,mull #aic #bfb4 ,breccia & blocks ( mica-s*i/1 qu>tzite1 etc41 ly+ betwe5 b$d$ basalts1 ,isle ( ,mull #aig #bfc4 ,section ( ,knocklayd1 an outli] ( ! ,antrim basalt-plateau ly+ on ,*alk #bjb #bfd4 ,diagram-,section ( ! ,antrim ,plateau #bjc #bfe4 ,view ,( ,basalt esc>pm5t1 ,giant's ,causeway1 ) ! ,amphi!atre & ,*imneys4 7,f a photograph by ,mr4 ,r4 ,wel*7 #bjg #bff4 ,basalt-capp+ on ! top ( ,b5 ,iada91 ,morv5 #bji #bff;a4 ,view ( ! s\? side ( ,/affa1 %[+ ! b$d$ & column> /ructure ( ! basalt #baj #bfg4 ,view ( ,rum f ! h>b\r ( ,canna #baf #bfh4 ,section ( ! cliffs bel[ ,compass ,hill1 ,isle ( ,canna #bah #bfi4 ,lava cutt+ out conglom]ate & %ale4 ,%ore bel[ ,canna ,h\se #bbd #bgj4 ,section ( %ales & tuffs1 ) a conif]\s /ump ly+ betwe5 two basalt-%eets1 ,cl nam ,m>bh1 ,canna #bbe #bga4 ,dn ,mr1 ,s&ay4 7,f a photograph by ,miss ,?om7 #bbf #bgb4 ,view ( ! ,dn ,beag1 ,s&ay1 se5 f ! s\?4 7,f a ,photograph by ,miss ,?om7 #bcj #bgc4 ,view ( ,dn ,beag1 ,s&ay1 f ! nor?4 ,! isl& ( ,rum 9 ! di/ance4 7,f a ,photograph by ,miss ,?om7 #bca #bgd4 ,section ( ea/]n front ( ,dn ,beag #bcb #bge4 ,enl>g$ section on ! we/]n side ( ,dn ,beag #bcc #bgf4 ,geological map ( ! ,isl& ( ,eigg #bce #bgg4 ,section ( ! geological /ructure ( ! ,isl& ( ,eigg #bcf #bgh4 ,view ( ! ,scuir ( ,eigg f ! ea/ #bcg #bgi4 ,natural section at ! cliff ( ,bideann ,boidhea*1 nor?-we/ end ( ! ,scuir ( ,eigg #bci #bhj4 ,view ( ! ,scuir ( ,eigg f ! s\? #bdb #bha4 ,view ( ! ,scuir ( ,eigg f ! s\?-we/ ( ! ,lo* a ,bhealai*1 %[+ ! b$d$ "* ( ! mass #bdc #bhb4 ,section at ! base ( ! ,scuir ( ,eigg 7ea/ end7 #bdd #bhc4 ,t]rac$ hills ( basalt plateau 7,macleod's ,tables71 ,skye #bej #bhd4 ,macleod's ,maid5s & "p ( basalt cliffs ( ,skye #bea #bhe4 ,int]calat$ gr\p ( /rata betwe5 ,basalts1 ,an ,ceannai*1 we/]n side ( ,skye #beb #bhf4 ,esc>pm5t ( ,plateau-basalts1 ,cliffs ( ,talisk]1 ,skye #bec #bhg4 ,section ( ! l>ge/ ( ,macleod's ,maid5s #bed #bhh4 ,dy+ out ( lava-b$s1 ea/ side ( ,s&1 ,f>oe ,isles #beg #bhi4 ,l5ticul> lavas1 we/]n front ( ,he/1 ,f>oe ,isles #beg #bij4 ,l5ticul> lavas1 ea/ side ( ,sv91 ,f>oe ,isles #beh #bia4 ,section at ,frodbonyp1 ,sud]1 ,f>oe #beh #bib4 ,fissure 7gj7 9 a lava-field1 ,icel&4 7,f a photograph by ,dr4 ,tempe/ ,&]son7 #bfb #bic4 ,cones on ! great ,laki fissure1 ,icel&4 7,f a photograph by ,dr4 ,tempe/ ,&]son7 #bfc #bic;a4 ,plan ( small crat]s along ! l9e ( great ,laki fissure1 ,icel&4 7,aft] ,mr4 ,hell&1 r$uc$7 #bfd #bid4 ,slemi%1 a volcanic neck or v5t on ! ,antrim plateau1 se5 f ! nor? #bgb #bie4 ,section ( volcanic v5t at ,c>nmony ,hill 7,e4 ,hull7 #bgb #bif4 ,section ( ! ea/ side ( ,scawt ,hill1 ne> ,gl5>m #bgc #big4 ,section ( ,neck ( basalt1 ,b5doo1 ,ball9toy #bgc #bih4 ,volcanic ,neck ( dol]ite ne> ,cu%5dall #bgd #bii4 ,section ( ,volcanic ,neck at ',s ,airde ,be9ne1 ne> ,tob]mory1 ,mull #bgd #cjj4 ,int]ior ( ! ,volcanic ,neck ( ',s ,airde ,be9ne1 ne> ,tob]mory1 ,mull #bge #cja4 ,diagram to %[ ! probable relation ( ! ,neck at ,c>rick-a-raide1 ,antrim1 to an adjac5t gr\p ( tuffs #bgg #cjb4 ,section ( agglom]ate ,neck at ,maclean's ,nose1 ,ardnamur*an #bgi #cjc4 ,diagram to %[ ! probable relations ( ! rocks on ! s\!rn flank ( ,be9n ,de>g ,bheag #bhb #cjd4 ,section ( ,volcanic ,v5t & connect$ lavas & tuffs1 ,scorr1 ,camas ,g>bh1 ,portree ,bay1 ,skye #bhd #cje4 ,section ( ! ,volcanic ,s]ies at ,a* na ,hannait1 s\? ( ,portree1 ,skye #bhh #cjf4 ,view ( "p ( a ,volcanic ,neck at ! ea/]n end ( ! isl& ( ,canna4 7,f a photograph by ,miss ,?om7 #bhi #cjg4 ,column> ,basalt invad+ agglom]ate ( ,volcanic ,v5t1 ,coroghon ,mr1 ,isle ( ,canna4 7,height above #bj feet7 #bia #cjh4 ,column> ,basalt invad+ ,volcanic conglom]ate1 nor? side ( ,alman ,islet1 ,canna #bia #cji4 ,view ( neck-l mass ( breccia1 ,bro*el1 ,raasay #bib #caj4 ,view ( ,volcanic ,neck pi]c+ & ov]la9 by ! ,plateau-,basalts1 ,/rom1 entrance ( ,vaagfjord1 ,f>oe ,isl&s4 7,f a photograph by ,colonel ,evans7 #bid #caa4 ,section ( ! same ,neck z t %[n 9 ,fig4 #caj #bie #cab4 ,volcanic ,neck close to t %[n 9 ,figs4 #caj & #caa #bif #cac4 ,section ( wall ( ano!r ,neck ( agglom]ate 9 ! same gr\p ) ^? repres5t$ 9 ,figs4 #caj1 #caa1 & #cab #bif #cad4 ,view ( ,segregation-,ve9s 9 a dol]ite sill1 ,portru%1 ,antrim #cjj #cae4 ,view ( ,fair ,head1 f ! ea/1 %[+ ! ma9 upp] sill & a ?9n] %eet cropp+ out along ! talus #cja #caf4 ,view ( ,fair ,head f ! %ore4 7,f a photograph by ,mr4 ,r4 ,wel*7 #cjb #cag4 ,section at ,f>rag&oo cliff1 we/ end ( ,fair ,head1 %[+ ! rapid splitt+ up & dy+ out ( an ,intrusive ,%eet slope #cjd #cah4 ,view ( ! ,trott]ni% ,coa/1 %[+ ! position ( ! b& ( ,sills #cje #cai4 ,column> ,sill intrusive 9 ,jurassic ,/rata ea/ ( ,kilm>t91 ,trott]ni%1 ,skye #cjf #cbj4 ,view ( ! nor!rn precipice 7#ejj feet high7 ( ! l>ge/ ( ! ,%iant ,isles4 7,f a photograph by ,colonel ,evans7 #cjh #cba4 ,section ( ?9 ,intrusive ,%eets & ,ve9s 9 c>bonace\s %ales ly+ among ! ,plateau-basalts1 cliffs nor? ( ,a* na ,hannait1 betwe5 ,portree ,bay & ,lo* ,sliga*an #caa #cbb4 ,upp] "p ( ,sill1 ,moon5 ,bay1 ,wat]ni%1 ,skye1 %[+ ! div]g5ce ( ve9s #cac #cbc4 ,section ( ! base ( ! ,basalt-plateau ) sill & dykes1 ,s\nd ( ,soa1 ,skye #cad #cbd4 ,section ( ,dol]ite ,sill cut by ano!r sill1 bo? be+ trav]s$ by dykes1 ,rudh' an ,iasgai*1 we/]n side ( ,sleat1 ,skye #caf #cbe4 ,section to %[ ,b$d$ & ,intrusive ,%eets1 ,eigg #cah #cbf4 ,gr\nd plan ( ,sills at ,b5 ,hiant1 ,ardnamur*an4 #cba #cbg4 ,section ( two ,sills 9 s*i/ose grits1 we/ end ( ,be9n na h-,ur*ra*1 ,ardnamur*an #cbb #cbh4 ,sill trav]s+ b$d$ ,basalts1 cliffs ( ,/rom1 at entrance ( ,vaagfjord #cbc #cbi4 ,view ( ! same ,sill se5 f ! *annel opposite ! isl& ( ,kolt] #cbd #ccj4 ,granulitic & co>sely foliat$ ,gabbro trav]s$ by lat] ve9s ( felspa?ic ,gabbro1 ,druim an ,eidhne1 ,cuill9 ,hills1 ,skye #cca #cca4 ,scuir na ,gillean1 ,cuill9 ,hills1 %[+ ! *>act]i/ic craggy =ms ( ! ,gabbro4 7,f a photograph by ,mr4 ,abraham1 ,keswick7 #cce #ccb4 ,section across ,gl5 ,brittle1 to %[ ! g5]al relations ( ! ,b$d$ ,basalts & ! ,gabbros #ccf #ccc4 ,view ( ! cre/ ( ! ,cuill9 ,hills1 %[+ ! wea!r+ ( ! ,gabbro along its jo9ts & ( a comp\nd basic dyke :i* rises ?r\gh x4 7,f a photograph by ,mr4 ,abraham1 ,keswick7 #cch #ccd4 ,section across ! ,coire ,uaignei*1 ,skye #cda #cce4 ,b&$ & puck]$ gabbro1 ,druim an ,eidhne1 ,gl5 ,sliga*an1 ,skye #cdb #ccf4 ,b&$ /ructure 9 ! ,gabbro1 f ! ridge ( ,druim an ,eidhne1 betwe5 ,lo* ,coruisk & ,gl5 ,sliga*an #cdc #ccg4 ,b&$ & d\bly fold$ ,gabbro1 ,druim an ,eidhne1 #aj feet broad #cde #cch4 ,sket* ( b&$ /ructure 9 ! ,gabbros ( ! hills at ! head ( ,lo* ,scavaig #cdg #cci4 ,outl9e ( ! hills ( ! ,isl& ( ,rum1 sket*$ f ne> ! ,isle ( ,eigg #cej #cdj4 ,view ( ,allival1 ,rum1 sket*$ f ! base ( ! nor?-ea/ side ( ! cone #ceb #cda4 ,section ( foliat$ ,gabbros 9 ! ,t]ti>y volcanic s]ies ( ,allival1 ,rum #cec #cdb4 ,alt]$ ,plateau-,basalts invad$ by ,gabbro1 & ) a ,dyke ( prismatic ,basalt cutt+ bo? rocks1 nor? slope ( ,b5 ,buy1 ,mull #ceg #cdc4 ,!oretical repres5tation ( ! /ructure ( "o ( ! ,gabbro bosses ( ! ,inn] ,hebrides #cfb #cdd4 ,section ?r\gh ! ,puy de la ,g\tte & ,puy de ,*op9e #cgd #cde4 ,view ( ! ,hu*e ,po9tue & ,hu*e ,platte we/ ( ,le ,p]tuis #cgf #cdf4 ,view ( ,glami*1 #becg feet1 ,gl5 ,sliga*an4 7,f a photograph by ,r4 ,j4 ,a4 ,b]ry1 ,m4,d41 l5t by ! ,scotti% ,m\nta9e]+ ,club7 #chj #cdg4 ,section across ! nor? slope ( ,be9n an ,dubhai*1 ,skye #chc #cdh4 ,section f ,be9n ,de>g to ,be9n an ,dubhai*1 ,skye #che #cdi4 ,section at nor? end ( ,be9n na ,cro1 ,skye #chh #cej4 ,gr\nd-plan ( basic dyke 9 ,cambrian lime/ones truncat$ by granophyre :i* encloses l>ge blocks ( ! dyke1 ,torr91 ,skye #cic #cea4 ,section on s\? side ( ,be9n an ,dubhai*1 ,skye1 %[+ ! truncation ( a basalt-dyke #cid #ceb4 ,view ( ! hills on ! s\? side ( ! head ( ,lo* na ,keal1 %[+ ! junction ( ! ,granophyre & ! b$d$ basalts #cif #cec4 ,section on s\? side ( ,crua* ,trr an ,lo*a91 ,mull #cih #ced4 ,section at head ( ,allt na ,se>mo91 ,mull #cih #cee4 ,section on s\? side ( ,be9n ,fhada1 ,mull #cii #cef4 ,section to s\? ( ,lo* na ,diridh1 ,mull #djj #ceg4 ,section ( junction ( s\? side ( ,lo* ,ba' ,granophyre boss1 ) ! b$d$ basalts1 ,mull #dja #ceh4 ,mass ( d>k gabbro ab\t two feet 9 diamet] trav]s$ by pale ve9s ( ,granophyre1 ly+ on nor? slope ( ,creag na h-,iolaire1 ,mull #djb #cei4 ,section at ,creag na h-,iolaire1 ,gl5 ,m1 ,mull1 %[+ basalts & gabbros re/+ on & pi]c$ by ,granophyre #djb #cfj4 ,section on nor? side ( ,orval1 ,rum #djd #cfa4 ,junction ( ,qu>tz-porphyry 7,microgranite7 & basic rocks1 s\?-ea/ side ( ,orval1 ,rum #djd #cfb4 ,junction ( ,granophyre & gabbro1 nor? side ( ,/4 ,kilda #daj #cfc4 ,ve9s ( ,granophyre trav]s+ gabbro & splitt+ up into ?9 ?reads1 nor? side ( ,/4 ,kilda #daa #cfd4 ,pale ,granophyre inject$ into d>k basalt1 ,s\? ,bay1 ,/4 ,kilda #dab #cfe4 ,ve9s ( ,granophyre trav]s+ a f9e-gra9$ gabbro & sc>cely ent]+ a co>se-gra9$ %eet1 we/ side ( ,rueval1 ,/4 ,kilda #dac #cff4 ,view ( sills & ve9s ( pale ,granophyre trav]s+ %eets ( gabbro1 we/ side ( ,/4 ,kilda4 7,f a photograph by ,colonel ,evans7 #dad #cfg4 ,section ( ! sea-cliff bel[ ,cona*]1 ,/4 ,kilda1 %[+ basic dykes 9 ,granophyre #dag #cfh4 ,triple basic dyke1 sea-cliff1 ea/ side ( ,/4 ,kilda #dag #cfi4 ,jo9t$ /ructure ( ! ,granite ne> ! top ( ,goatfell1 ,arran4 7,f a photograph by ,mr4 ,w4 ,d\glas1 l5t by ! ,scotti% ,m\nta9e]+ ,club7 #dai #cgj4 ,intrusive ,rhyolite 9 ! l[] basalt gr\p ( ,antrim1 ,templepatrick #dbg #cga4 ,section across ! s\!rn slope ( ,c>ne>ny ,hill1 ,antrim #dbg #cgb4 ,section across ! ,granophyre ,sills at ,lo* a' ,mhullai*1 above ,skulamus1 ,skye #dcc #cgc4 ,section to %[ ! connection ( a sill ( ,granophyre ) its probable funnel ( supply1 ,raasay #dcf #cgd4 ,granophyre sill re/+ on ,l[] ,lias %ales ) a dyke ( basalt pass+ lat]ally into a sill1 ,suisni% ,po9t1 ,isle ( ,raasay #dcf #cge4 ,wea!r$ surface ( sph]ulitic ,granophyre f dyke 9 b&$ gabbros1 ,druim an ,eidhne1 ,meall ,de>g1 ,gl5 ,sliga*an1 ,skye4 ,natural size #dch #cgf4 ,plan ( portion ( ! ridge nor? ( ,druim an ,eidhne1 ,gl5 ,sliga*an1 ,skye1 %[+ ?ree dykes issu+ f a mass ( ,granophyre #dci #cgg4 ,wea!r$ surface ( sph]ulitic ,granophyre1 f dyke 9 b&$ gabbros1 ,druim an ,eidhne1 ,meall ,de>g1 ,gl5 ,sliga*an1 ,skye4 ,natural size #ddj #cgh4 ,plan ( pale ,granophyric dyke1 ) sph]ulitic & fl[-/ructure1 cutt+ & enclos+ d>k gabbro1 ,druim an ,eidhne #dda #cgi4 ,dyke 7six to t5 feet broad7 proce$+ f a l>ge body ( ,granophyre & trav]s+ gabbro1 f ! same locality z ,figs4 #cge & #cgg #ddb #chj4 ,section ( intrud$ ve9s ( v>i\s acid rocks above ,riv] ,cla*aig1 ,mull #ddc #cha4 ,pit*/one ve9 trav]s+ ! b$d$ basalts1 ,rudh an ,tangairt1 ,eigg #dde #chb4 ,rev]s$ fault on ! ea/]n side ( ,sv91 ,f>oe ,isles #ded #chc4 ,rev]s$ fault on ! nor?-ea/ headl& ( ,s&1 ,f>oe ,isle #ded ,,maps ,v4 ,map ( ! ,p]mian volcanic di/ricts ( ,scotl& ,to face p4 #ajf ,,vi4 ,map ( ! ,t]ti>y volcanic region ( ! ,we/ ( ,scotl& ,to face p4 #bif ,,vii4 ,map ( ! ,t]ti>y volcanic di/rict ( ! ,nor?-,ea/ ( ,irel& ,to face p4 #ddf ,,*apt] ,,xxix ,,! ,,c>bonif]\s ,,volcanoes ,,( ,,engl& ,! ,nor? ( ,engl&3 ,dykes1 ,! ,great ,:9 ,sill--,! ,d]by%ire ,toad/ones--,! ,isle ( ,man--,ea/ ,som]set--,devon%ire #a4 ,,! ,,nor? ,,( ,,engl& ,! volcanic int]calations :i* div]sify ! ,l[] ,c>bonif]\s =mations ( ,s\!rn ,scotl& ext5d b a %ort way across ! ,engli% ,bord]1 & al?\gh1 ov] ! moors & hills ( ! nor? ( ,cumb]l& & ,nor?umb]l&1 ! ,c>bonif]\s s&/ones1 lime/ones & %ales are well expos$1 !y pres5t no cont9uation ( ei!r ! plateau or puy-eruptions :i* play s prom95t a "p 9 ! geology ( ,roxburgh%ire & ,dumfries%ire4 ,?is defici5cy is all ! m noticeable see+ t ! ,c>bonif]\s sy/em is expos$ d[n to its v base1 9 ! deep dales ( ! ,nor? ( ,engl&4 ,_h any truly int]/ratifi$ volcanic mat]ial exi/$ 9 ! sy/em !re1 x c\ld h>dly fail to h be5 detect$4 ,b :ile contemporane\s volcanic rocks are abs5t1 ! nor!rn ,engli% c\nties conta9 _m intrusive masses ( dol]ite1 diabase1 &esite or o!r eruptive rocks1 :i* may be f\nd trav]s+ all ! subdivisions ( ! ,c>bonif]\s sy/em4 ,^! eruptive mat]ials h tak5 two =ms3 9 "s cases !y rise z ,dykes1 9 o!rs !y appe> z ,sills4 ,dykes4--,) reg>d to ! dykes1 "s are probably mu* lat] ?an ! ,c>bonif]\s p]iod1 & consequ5tly w be m appropriately consid]$ 9 ,*apt]s xxxiv4 & xxxv4 ,! great ,clevel& dyke1 = example1 :i* runs across ! ,c>bonif]\s1 ,p]mian1 ,triassic & ,jurassic =mations1 is probably ref]able to ! ,old] ,t]ti>y volcanic p]iod4 ,"o dyke kn[n z ! ,hett ,dyke1 has be5 plausibly claim$ z possibly ( ,c>bonif]\s age4 ,x runs 9 a ,w4,s4,w4 direction f ! ,magnesian ,lime/one esc>pm5t at ,qu>r+ton ,hill1 a few miles to ! ea/ ( ,durham1 ?r\gh ! great ,coal-field1 across ! ,mill/one ,grit & ,c>bonif]\s ,lime/one1 disappe>+ ne> ,middleton 9 ,teesdale4 ,its total l5g? is ?us ab\t #bc miles4 ,x v>ies 9 bread? f ab\t #f to ab\t #ae feet1 & appe>s to increase 9 dim5sions z x goes we/w>d4#a ,footnote #a3 ,s$gwick1 ,trans4 ,geol4 ,soc4 #bnd s]ies1 iii4 "p #a 7#ahbf-bh71 p4 #fc2 ,trans4 ,cambridge ,phil4 ,soc4 ii4 7#ahbb71 p4 #ba4 ,sir ,j4 ,l[?ian ,bell1 ,proc4 ,roy4 ,soc4 xxiii4 7#ahge71 p4 #edc4 ,! age ( ?is dyke _c at pres5t be satisfactorily fix$4 ,x mu/ be lat] ?an ! ,coal-measures ?r\gh :i* x rises4 ,s$gwick long ago po9t$ out t ?\gh x rea*es ! esc>pm5t ( ! ,magnesian ,lime/one1 x does n cut x2 yet x is f\nd 9 coal-m9+ to trav]se ! ,coal-measures und]ly+ ! ,lime/one4 ,he 0 accord+ly incl9$ to believe x to be ( old] date ?an ! ,magnesian ,lime/one4 ,at its we/]n extremity x approa*es close to ! ,great ,:9 ,sill ( ,teesdale1 ?\gh no absolute connection betwe5 ! two has be5 e/abli%$4 ,mr4 ,teall1 h[ev]1 has call$ att5tion to ! simil>ity betwe5 ! microscopic /ructure ( ! rock =m+ ! ,hett ,dyke & t ( ! mass ( ! ,:9 ,sill1 & he is /rongly incl9$ to reg>d !m z belong+ to ! same p]iod ( intrusion4#b ,footnote #b3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 7#ahhd71 p4 #bcj4 ,x is especially wor?y ( rem>k t 9 ! c\rse ( its ne>ly rectil9e> c\rse across ! ,durham ,coal-field1 ! ,hett ,dyke1 :]e x crosses ! ,we>1 is flank$ on ! nor? at a di/ance ( a little m ?an two miles by a second p>allel dyke ( ne>ly id5tical composition4 ,betwe5 ! two dykes1 dur+ m9+ op]ations1 a sill ab\t #bj feet ?ick has be5 met )1 ly+ betwe5 two well-kn[n coal-seams at a dep? ( ab\t #fj fa?oms f ! surface1 & ext5d+ ov] an area ( at lea/ #ae acres4#c ,microscopic exam9ation ( ?is sill by ,mr4 ,teall prov$ t ! rock pres5ts ! close/ resemblance to t ( ! ,hett ,dyke4#d ,9 ?is case1 x may be reg>d$ z probable t ! two dykes & ! int]m$iate sill =m "o relat$ s]ies ( intrusions1 & ! conjecture t ! ,hett ,dyke may be connect$ ) ! ,:9 ,sill ?us receives corroboration4 ,! age ( ! ,:9 ,sill itself w be discuss$ a few pages fur!r on4 ,footnote #c3 ,sir ,l[?ian ,bell1 ,proc4 ,roy4 ,soc4 xxiii4 7#ahge71 p4 #edd4 ,footnote #d3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 7#ahhd71 p4 #bcj4 ,( ! o!r dykes :i* may possibly be coeval ) ! ,hett ,dyke we may specially note ^? :i* foll[ ! same ,w4,s4,w4 tr5d1 = t /rike diff]s f ! g5]al ,w4,n4,w4 direction ( mo/ ( ! dykes4 ,two conspicu\s examples ( ! s\?-we/]ly tr5d may be se51 "o ne> ,morpe?1 ! o!r nor? ( ,bell+ham4 ,! =m] dyke1 z reg>ds microscopic /ructure1 is m ne>ly relat$ to ! majority ( ! s]ies 9 ! ,nor? ( ,engl&4 ,b t nor? ( ,bell+ham 7,high ,gre57 pres5ts aff9ities bo? 9 /ructure & composition ) ! ,hett ,dyke1#e & may p]haps belong to ! same p]iod ( intrusion4 ,footnote #e3 ,mr4 ,teall1 op4 cit4 p4 #bdd4 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxxix4 7#ahhd71 p4 #fef1 & ,proc4 ,geol4 ,assoc4 7#ahhf74 ,see also ,pr(4 ,leb\r1 ,geology ( ,nor?umb]l& & ,durham1 *ap4 xi4 ,! ,great ,:9 ,sill4--,! geologi/ :o1 aft] mak+ himself acqua9t$ ) ! abundant sills among ! ,c>bonif]\s rocks 9 ! c5tre ( ,scotl&1 f9ds 8 way into ,nor?umb]l&1 meets !re ) geological features t h become famili> to him fur!r nor?4 ,! sea-cliffs ( ,bambor\gh & ,dun/anbor\gh1 ! rocky islets ( ,f>ne1 ! long l9es ( br[n crag & gre5 slope t /rike inl& ?r\gh ! ,kyloe ,hills & w9d across ! cultivat$ l[l&s & ! moorl&s beyond1 rem9d him at e turn ( ! sc5]y 9 ! bas9 ( ! ,=?4 ,b n until he has trac$ ^! ridges = _m miles s\?w>ds & f\nd _! compon5t rocks to =m !re an almo/ cont9u\s %eet does he realize t no?+ ( ! k9d among ! ,scotti% ,c>bonif]\s rocks c be comp>$ = ext5t to ?is display 9 ! ,nor? ( ,engl&4#f ,footnote #f3 ,! ,:9 ,sill has be5 ! subject ( mu* discussion1 & a good deal ( geological lit]ature has be5 devot$ to its consid]ation4 ,! writ+s ( ,trevelyan1 ,s$gwick1 ,w4 ,hutton1 ,phillips & ,tate are especially des]v+ ( recognition4 ,! intrusive "* ( ! ,sill1 ma9ta9$ by "s ( ^! writ]s1 0 f9ally e/abli%$ by ! mapp+ ( ! ,geological ,survey1 & 0 discuss$ & illu/rat$ by ,messrs4 ,w4 ,topley & ,g4 ,a4 ,leb\r 9 a pap] 9 ! #ccrd volume ( ! ,qu>t4 ,j\rn4 ,geol4 ,soc4 7#ahgg71 9 :i* ref]5ces to ! e>li] obs]v]s w be f\nd4 ,see also ,pr(4 ,leb\r's ,outl9es ( ! ,geology ( ,nor?umb]l&1 #bnd edit4 7#ahhf71 p4 #ib4 ,! petrography ( ! ,:9 ,sill is fully treat$ by ,mr4 ,teall 9 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 7#ahhd71 p4 #fdj1 :]e a bibliography ( ! subject is also giv54 ,f ! fur!/ sk]ries ( ! ,f>ne ,isl&s s\?w>ds to ,burton ,fell on ! great ,p5n9e esc>pm5t1 a di/ance 9 a /raight l9e ( ab\t #hj miles1 ?is intrusive %eet may be trac$ 9 ! ,c>bonif]\s ,lime/one s]ies 7,map ,i474 ,!re are int]vals :]e its cont9uity _c be actually foll[$ at ! surface1 b t x really runs unbrok5 f "o end to ! o!r und]gr\nd _c be d\bt$ by any "o :o has exam9$ ! region4 ,?is s+ul> feature 9 ! geology & sc5]y ( ! ,nor? ( ,engl& is kn[n locally z ! ,great ,:9 ,sill4#g ,f ! rocky islets & ca/le-cr[n$ crags ( ! coa/-l9e x ma9ta9s its *>act]i/ic topography1 /ructure & composition ?r\gh\t its long c\rse 9 ! int]ior4 ,s regul>ly p>allel ) ! s$im5t>y /rata does x appe> to lie1 t x 0 =m]ly reg>d$ by _m obs]v]s z a true lava-%eet1 p\r$ out ^u ! sea-floor ov] :i* ! lime/ones & %ales 7 laid d[n4 ,b its really intrusive "* has n[ be5 cle>ly demon/rat$4 ,n a ve/ige ( any tuff has be5 detect$ associat$ ) x1 nor does x ev] pres5t ! usual *>act]s ( a true lava-/ream4#h ,its int]nal /ructure & ! wond]ful uni=mity 9 its "* m>k x out z a typical intrusive %eet4 ,footnote #g3 ,:9 is a common t]m 9 ,scotl& & ! ,nor? ( ,engl& = any h>d k9d ( /one1 especially su* z c be us$ = mak+ & m5d+ roads4 ,sill d5otes a flat c\rse or b$ ( /one1 & 0 evid5tly appli$ to ?is intrusive %eet f its p]si/5t flat-b$d$ position & its prom95ce among ! o!r g5tly incl9$ /rata among :i* x lies4 ,x is f ?is example 9 ! ,nor? ( ,engl& t ! ^w sill has pass$ into geological lit]ature4 ,footnote #h3 ,on ! coa/ at ,bambor\gh & ! ,h>kess ,rocks ! usual petrographical *>act]s ( ! ,:9 ,sill are ex*ang$ = ^? ( f9e-gra9$ amygdaloidal diabases arrang$ 9 di/9ct %eets1 :i* 9 _! upp] p>ts are highly vesicul> & %[ ropy surfaces--peculi>ities sugge/ive ( true lava-/reams4 ,b accord+ to ,pr(essor ,leb\r ! rocks are intrusive into lime/one & %ale 7,geology ( ,nor?umb]l& & ,durham1 p4 #ih74 ,mr4 ,teall has express$ ! suspicion t ^! rocks mu/ h consolidat$ "u conditions some:at diff]5t f ^? :i* *>act]iz$ ! normal ,:9 ,sill 7,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 p4 #fdc74 ,!y seem to be ! only p>ts ( ! sill :i* pres5t features t might possibly indicate sup]ficial outfl[4 ,among ! manife/ations ( ! subt]ranean intrusion ( igne\s rocks 9 ! ,briti% ,isles ! ,great ,:9 ,sill1 next aft] ! ,dalradian sills ( ,scotl&1 is ! mo/ ext5sive4 ,its /rik+ cont9uity = s great a di/ance1 & ! abs5ce ar\nd x ( any o!r trace ( igne\s action1 save a few dykes1 place x 9 m>k$ contra/ to ! ord9>y type ( ,c>bonif]\s sills4 ,! occasional gaps on its l9e ( outcrop 9 ! nor!rn "p ( its c\rse d n really affect our impression ( ! p]si/5ce ( ! %eet4 ,!y n improbably indicate m]ely t 9 its protrusion x _h a wavy irregul> limit1 :i* 9 ! progress ( d5udation has occasionally be5 n yet rea*$4 ,= mile aft] mile ! sill has be5 mapp$ by ! ,geological ,survey 9 l9es ( crag across ! moorl&s1 & z a conspicu\s b& among ! lime/ones & %ales t =m ! /eep front ( ! ,p5n9e esc>pm5t1 :]e x has long be5 kn[n 9 ! f9e sections expos$ among ! gullies by :i* t noble rock-face has be5 furr[$4 ,illu/ration3 ,fig4 #agf4--,section f ! great ,lime/one esc>pm5t on ! we/ to ! ,mill/one ,grit hills ea/ ( ,teesdale4 #a4 ,silurian /rata2 #b4 ,c>bonif]\s ,lime/one s]ies2 #c4 ,! ,great ,:9 ,sill1 :i* gradually rises to high] /ratigraphical position z x goes we/w>d2 #d4 ,mill/one ,grit4 ,along its ma9 outcrop1 ! sill dips g5tly ea/w>ds bel[ ! portion ( ! ,c>bonif]\s ,lime/one s]ies :i* ov]lies x4 ,b s slight are ! incl9ations1 s g5tle ! undulations ( ! rocks 9 ?is "p ( ! c\ntry1 t f> to ! ea/ ( t outcrop ! sill has be5 laid b>e by ! /reams :i* 9 ! l>g] dales h cut _! way ?r\gh ! ov]ly+ cake ( ,c>bonif]\s /rata d[n to ! ,silurian plat=m on :i* !y re/ 7,fig4 #agf74 ,among ^! inl& revelations ( ! ea/w>d cont9uation ( ! sill "u ,c>bonif]\s ,lime/one /rata1 ! mo/ /rik+ & be/ kn[n are ^? :i* h be5 made by ! ,riv] ,tees1 & ( :i* ! fam\s wat]falls ( ! ,high ,=ce & ,cauldron ,sn\t are ! mo/ picturesque features4 ,! di/ance ( ! remote/ ( ^! d5ud$ outcrops or inli]s f ! ma9 esc>pm5t is n less ?an #bj miles4 ,x is n possible to =m an accurate e/imate ( ! total und]gr\nd area ( ! ,:9 ,sill4 ,9 ! s\!rn half ( ! di/rict1 s\? ( ! l9e ( ! ,roman ,wall1 :]e1 ! incl9ation ( ! /rata be+ g5]ally l[1 ! same /ratigraphical horizons are expos$ by d5udation f> to ! ea/ ( ! ma9 outcrops ( ! rocks1 we "k t ! sill mu/ h a subt]ranean ext5t ( m ?an #djj squ>e miles4 ,yet ?is is probably only a small "p ( ! total area ov] :i* ! molt5 mat]ial 0 inject$4 ,9 ! nor!rn "p ( ! di/rict1 ! ,c>bonif]\s ,lime/one s]ies is n expos$ ov] s broad a /ret* ( c\ntry1 & d5udation has n !re reveal$ ! ea/w>d ext5sion ( ! sill4 ,b !re is no reason to suppose ! %eet to be less cont9u\s & massive !re4 ,we mu/ rememb] also t ! pres5t esc>pm5t has be5 produc$ by d5udation1 & t ! intrusive %eet mu/ h once ext5d$ we/w>ds beyond its pres5t limits at ! surface4 ,if1 !re=e1 we 7 to /ate broadly t ! ,great ,:9 ,sill has be5 intrud$ into ! ,c>bonif]\s ,lime/one s]ies ov] an area ( #ajjj squ>e miles we %\ld probably be /ill bel[ ! tru?4 ,! rock compos+ ?is va/ intrusive %eet is a dol]ite or diabase1 :i* ma9ta9s ?r\gh\t its wide ext5t a rem>kable uni=mity ( petrographical *>act]s4 ,9 ?is & o!r respects x illu/rates ! typical features ( sills4 ,?us x is co>se/ 9 texture :]e x is ?icke/1 & some:at f9] 9 gra9 t[>ds its upp] & l[] surfaces ?an 9 ! c5tre4 ,among ! co>s] v>ieties ! compon5t cry/als ( augite are n infrequ5tly an in* 9 l5g? & occur 9 irregul> pat*es4#i ,occasional amygdaloidal portions are obs]vable1 b ^! are n m m>k$ ?an ^? to be f\nd 9 ! :9-dykes ( ! same region4#aj ,! amygdaloidal & vesicul> f9e-gra9$ rocks ( ! ,bambor\gh di/rict may possibly be q di/9ct f ! ma9 body ( ! ,:9 ,sill4 ,footnote #i3 ,s$gwick1 ,cambridge ,phil4 ,trans4 ii4 p4 #aff4 ,mr4 ,teall1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 p4 #fdc4 ,footnote #aj3 ,messrs4 ,topley & ,leb\r1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxxiii4 p4 #dah4 ,"u ! microscope ! rock is se5 to consi/ ess5tially ( ! usual m9]als--plagioclase1 augite & titanif]\s magnetic iron-ore4 ,an ophitic int]gr[? ( ! augite & felsp> is obs]vable1 likewise a c]ta9 quantity ( micropegmatite :i* plays ! "p ( gr\ndmass betwe5 ! int]/ices ( ! la?-%ap$ felsp>s4 ,full details ( ! *>act]i/ics ( ! compon5t m9]als & _! arrangem5t are giv5 by ,mr4 ,teall 9 ! pap] already cit$4 ,! ma9 body ( ! sill is a %eet :i* sometimes dim9i%es to less ?an #bj feet 9 ?ickness & sometimes exp&s to #aej feet1 b av]ages f #hj to #ajj feet4 ,x occasionally divides1 z ne> ,great ,bav+ton1 :]e x appe>s at ! surface 9 two di/9ct b$s sep>at$ by an int]v5+ gr\p ( lime/ones & %ales4 ,occasionally1 z at ,elf's ,hill ,qu>ry1 x gives out bran*es :i* s5d /r+s into ! adjac5t lime/one4#aa ,footnote #aa3 ,messrs4 ,topley & ,leb\r1 op4 cit4 p4 #dac4 ,al?\gh 9 mo/ natural sections x seems to lie q p>allel ) ! /rata above & bel[1 yet a numb] ( examples ( its actual intrusion h be5 obs]v$4 ,:5 trac$ across ! c\ntry1 x is f\nd n to rema9 on a def9ite horizon1 b to pass transgressively across consid]able ?icknesses ( /rata4 ,its v>iations 9 ?is respect are well %[n 9 ! accompany+ table ( comp>ative sections con/ruct$ by ,messrs4 ,topley & ,leb\r4#ab ,x w be se5 t :ile at ,h>l[ ,hill ! sill is f\nd ov]ly+ ! ,great ,lime/one ( ,al/on ,moor1 at ,rugley1 five miles (f x lies ab\t #ajjj feet l[] d[n1 f> bel[ ! position ( ! ,tyne-bottom ,lime/one4 ,/ill f>!r nor?1 h[ev]1 ! sill we/ ( ,holy ,isl& is said to lie #hjj feet above ! ,great ,lime/one & to come among ! high] b$s ( ! ,c>bonif]\s ,lime/one s]ies4#ac ,footnote #ab3 ,op4 cit4 plate xviii4 ,footnote #ac3 ,op4 cit4 p4 #dad4 ,! ,:9 ,sill appe>s g5]ally to ?ick5 9 an ea/]ly or nor?-ea/]ly direction4 ,!re are fur!r indications t x 0 intrud$ f ea/ to we/4 ,?us1 at ,%eph]d's ,gap1 on ! ,great ,roman ,wall1 ! dol]ite1 com+ evid5tly f an ea/]ly qu>t]1 has brok5 up & ?ru/ itself b5ea? a b$ ( lime/one4 ,aga91 :5 ! sill bifurcates ! bran*es unite t[>ds ! ea/ or nor?-ea/4#ad ,! sill c be prov$ to ?9 away to ! we/ f ,teesdale to ! ,p5n9e esc>pm5t1 & 9 ,we>dale ! ,little ,:9 ,sill dim9i%es f #bj feet1 till 9 ?ree miles x disappe>s4#ae ,footnote #ad3 ,op4 cit4 p4 #dae4 ,footnote #ae3 ,op4 cit4 p4 #dai4 ,illu/ration3 ,walk] ,bontall sc4 ,fig4 #agg4--,sections ( ! ,c>bonif]\s ,lime/one s]ies ( ,nor?umb]l& %[+ ! v>iations 9 ! position ( ! ,:9 ,sill4 ,by ,messrs4 ,topley & ,leb\r4 ,! /rata 9 contact ) ! ,:9 ,sill1 bo? above & bel[1 h be5 m or less alt]$4 ,s&/ones h be5 lea/ affect$2 %ales h suff]$ mo/1 pass+ into a k9d ( porcellanite1 ) developm5t ( g>net & o!r m9]als4#af ,lime/one (t5 %[s only slight traces ( *ange1 ?\gh "h & !re x has become cry/all9e4 ,footnote #af3 ,mr4 ,teall1 op4 cit4 xxxix4 7#ahhd71 p4 #fdb1 & au?ors cit$ by him4 ,no trace ( any boss or neck has be5 detect$ 9 ! :ole region :i* might be suppos$ to m>k a funnel ( asc5t = ! mat]ial ( ! ,:9 ,sill4 ,! ,hett ,dyke & ! ,high ,gre5 ,dyke1 already notic$1 may1 h[ev]1 h be5 possibly connect$ ) ! injection ( ?is great intrusive %eet4 ,no o!r visible mass ( igne\s rock 9 ! region has be5 ev5 plausibly conjectur$ to indicate a po9t or l9e ( emission = ! sill4 ,x is c]ta9ly s+ul> t 9 s wide a t]ritory1 :]e ! :ole succession ( /rata has be5 s admirably laid b>e by d5udation 9 ?\s&s ( natural sections1 & :]e1 moreov]1 mu* additional in=mation has be5 obta9$ f lead-m9+ z to ! nature ( ! rocks bel[ gr\nd1 n a s+le ve/ige ( tuff1 agglom]ate or int]/ratifi$ lava has be5 up to ! pres5t "t record$1 unless ! ,h>kess rocks already allud$ to c be s reg>d$4 ,judg+1 h[ev]1 f ! analogy ( ! o!r di/ricts ( igne\s rocks 9 ,brita91 we c h>dly resi/ ! conclusion t ! ,great ,:9 ,sill is ess5tially a manife/ation ( volcanic action1 t x 0 connect$ ) ! uprise ( basic lava 9 volcanic orifices1 & t ! subt]ranean en]gy may q probably h succe$$ 9 rea*+ ! surface & eject+ !re bo? lavas & tuffs4 ,x appe>s to be c]ta9 t any v5ts :i* exi/$ _c h la9 to ! we/ ( ! pres5t esc>pm5t ( ! sill1 = no trace ( !m c be f\nd !re pi]c+ ! ,c>bonif]\s or old] =mations4 ,!y mu/ h la9 some:]e to ! ea/ 9 ! area n[ ov]spread ) ,mill/one ,grit & ,coal-measures1 or /ill f>!r ea/ 9 ! tract n[ conceal$ "u ! ,nor? ,sea4 ,! evid5ce ( ! sill itself1 z we h se51 corroborates ?is view ( ! probable situation ( ! c5tre ( di/urbance4 ,! "q ( ! geological age ( ! sill is "o ( consid]able difficulty1 to :i* no confid5t answ] c be giv54#ag ,! injection ( ! diabase mu/ obvi\sly be consid]ably lat] ?an ! highe/ /rata ?r\gh :i* x has ris52 t is1 x mu/ be y\ng] ?an "s ( ! high] memb]s ( ! ,c>bonif]\s ,lime/one s]ies4 ,b "h our positive evid5ce fails4 ,footnote #ag3 ,see ,messrs4 ,topley & ,leb\r1 op4 cit4 p4 #dah4 ,! ,sill is trav]s$ by ! same faults :i* disrupt ! surr\nd+ ,c>bonif]\s rocks4 ,x is !re=e ( old] date ?an ^! dislocations4 ,its /rik+ g5]al p>allelism ) ! %ales & lime/ones probably proves t x 0 intrud$ be=e ! rocks 7 mu* di/urb$ f _! orig9al horizontal position4 ,b ! mann] 9 :i* ! intrusive rock has be5 ?ru/ into & has involv$ ! %ales & lime/ones seems to indicate t ^! /rata _h already become consolidat$ & lay "u ! pressure ( a great ?ickness ( sup]9cumb5t ,c>bonif]\s /rata4 ,9 ! abs5ce ( all c]ta9ty on ! subject x seems mo/ natural to place ! ,:9 ,sill provisionally among ! ,c>bonif]\s volcanic s]ies ) :i* petrographically & /ructurally x has s mu* 9 common4 ,9 ,scotl& ! puy-eruptions cont9u$ till ! "t ( ! ,coal-measures4 ,if1 be=e ! close ( ! ,c>bonif]\s p]iod1 volcanic v5ts 7 op5$ some:]e to ! ea/ ( ! coal-fields ( ,nor?umb]l& & ,durham1 !y might be accompani$ ) basic sills inject$ into ! ,c>bonif]\s ,lime/one s]ies1 :i* 0 !n ly+ /ill approximately horizontal "u a ?ickness ( f #cejj to #ejjj feet ( ,c>bonif]\s s$im5t>y deposits4 ,^! /ill undiscov]$ volcanoes seem to h be5 end[$ ) ev5 m en]gy ?an ^? ( ,c5tral & ,s\!rn ,scotl&1 at lea/ n[h]e else among ! ,c>bonif]\s records ( ,brita9 is !re su* a colossal manife/ation ( subt]ranean intrusion z ! ,great ,:9 ,sill4 #b4 ,,! ,,d]by%ire ,,toad/ones ,9 ! abs5ce ( any c]ta9 evid5ce t ! ,:9 ,sill belongs to ! ,c>bonif]\s p]iod1 we mu/ advance s\?w>d into ! v he>t ( ,engl& be=e any cle> ve/iges c be f\nd ( contemporane\s volcanic eruptions among ! memb]s ( ! ,c>bonif]\s sy/em4 ,aft] quitt+ ! lavas & tuffs ( ,roxburgh%ire & _! brief cont9uations across ! ,engli% bord]1 we d n aga9 meet ) any truly b$d$ volcanic rocks 9 t sy/em until we rea* ! middle ( ,d]by%ire4 ,9 ?is picturesque di/rict1 fam\s = its lead-m9es & its m9]al wat]s1 a feebly develop$ b int]e/+ gr\p ( int]calat$ lavas1 locally call$ toad/ones1 has long be5 kn[n4 ,!re is ?us a space ( "s #aej miles across :i*1 ?\gh ! =mations are !re s fully develop$ & s abundantly tr5*$ by valleys f ! top to ! bottom ( ! sy/em1 no volcanic v5ts nor any trace ( ,c>bonif]\s volcanic ejections has yet be5 f\nd4 ,on ! o!r h&1 aft] ! di/rict ( ! toad/ones is pass$1 ! ,c>bonif]\s rocks are aga9 de/itute ( any volcanic int]calations across ! c5tre & s\?-we/ ( ,engl& & ov] ,wales1 until aft] a space ( ab\t #aej miles !y reappe> 9 ,som]set4 ,! volcanic gr\p ( ,d]by%ire ?us /&s out entirely isolat$4 ,ly+ 9 ! ,c>bonif]\s ,lime/one1 :]e t =mation is typically develop$1 x pres5ts an admirable example ( a ?or\ghly m>9e phase ( volcanic action 7,map ,i474 ,"o ( ! mo/ prom95t features 9 ! geology ( ! c5tre ( ,engl& is ! broad anticl9al fold :i* br+s up ! l[] portion ( ! ,c>bonif]\s sy/em to =m ! long ridge ( ! ,p5n9e *a9 t runs f ,york%ire to ! ,midl& pla91 & sep>ates ! ea/]n f ! we/]n coal-fields4 ,?is fold wid5s s\?w>ds until n only ! ,mill/one ,grit & ,yor$ale rocks1 b ! und]ly+ ,m\nta9 ,lime/one is laid b>e4 ,a broad lime/one di/rict is ?us expos$ 9 ! v he>t ( ! c\ntry1 rang+ z a gre5 f]tile undulat+ tablel&1 deeply cut by w9d+ valleys1 :i* expose admirable sections ( ! /rata1 b n[h]e rea* ! base ( ! sy/em4 ,! total visible dep? ( ! lime/one s]ies is comput$ to be ab\t #aejj feet2 ! ,yor$ale %ales & lime/ones may be #ejj feet m2 s t ! calc>e\s =mations 9 :i* ! volcanic ph5om5a are exhibit$ rea* a ?ickness ( at lea/ #bjjj feet4 ,x is n yet def9itely kn[n ?r\gh :at v]tical ext5t ( ?is ?ickness ( s$im5t>y mat]ial ! volcanic plat=ms ext5d1 b :]e mo/ fully develop$ !y p]haps range ?r\gh #ajjj feet1 ly+ *iefly 9 ! ,c>bonif]\s ,lime/one1 b app>5tly 9 at lea/ "o locality ext5d+ up into ! l[] division ( ! ,yor$ale gr\p4 ,! area )9 :i* !y c be /udi$ corresponds ne>ly ) t 9 :i* ! lime/one =ms ! surface ( ! c\ntry1 or a di/rict measur+ ab\t #bj miles f nor? to s\?1 ) an extreme bread? ( #aj miles 9 an ea/ & we/ direction4 ,a special hi/orical int]e/ belongs to ! ,d]by%ire toad/ones4#ah ,!y furni%$ ,:itehur/ ) mat]ial = 8 speculations1 & 7 believ$ by him to be z truly igne\s rocks z ! lava :i* fl[s f ,hecla1 ,vesuvius or ,etna4 ,b he ?\ght t !y _h be5 introduc$ among ! /rata & did n ov]fl[ ! surface ( ! e>?1 accord+ to ! usual op]ations ( volcanoes4#ai ,footnote #ah3 ,?is ^w has by "s writ]s be5 suppos$ to be corrupt$ f tod-/e91 dead-/one1 9 allusion to ! dy+ out ( ! lead ve9s !re2 by o!rs ! "n has be5 ?\ght to be d]iv$ f ! peculi> gre5 speckl$ aspect ( mu* ( ! rock1 resembl+ ! back ( a toad4 ,footnote #ai3 ,an ,enquiry into ! ,orig9al ,/ate & ,=mation ( ! ,e>?1 #aggh1 ,app5dix1 pp4 #adi1 et seq4 ,8 views 7 publi%$ z f> back z #aggh1 ?ree ye>s aft] ,hutton read ! fir/ outl9e ( 8 !ory ( ! e>? & made kn[n 8 obs]vations reg>d+ ! igne\s orig9 ( :9/ones4#bj ,! fir/ detail$ acc\nt ( ! ,d]by%ire eruptive rocks 0 t giv5 by ,fairey1#ba :i* has s]v$ z ! basis ( all subsequ5t descriptions4 ,conybe>e1 9 p>ticul>1 prep>$ a succ9ct n>rative f ,fairey's m diffuse /atem5ts1 & ?us plac$ cle>ly be=e geologi/s ! nature & di/ribution ( ^! volcanic int]calations4#bb ,subsequ5tly ! di/rict 0 mapp$ by ,de la ,be*e & ! (fic]s ( ! ,geological ,survey1 & ! areas occupi$ by ! sev]al outcrops ( igne\s rock c\ld !n be readily se54#bc ,footnote #bj3 ,trans4 ,roy4 ,soc4 ,ed94 i4 p4 #bge1 et seq4 ,hutton specially m5tions ! toad/one ( ,d]by%ire z "o ( ! rocks produc$ by fusion1 p4 #bgg4 ,footnote #ba3 ,g5]al ,view ( ! ,agriculture & ,m9]als ( ,d]by%ire 7#ahaa74 ,footnote #bb3 ,outl9es ( ! ,geology ( ,engl& & ,wales 7#ahbb71 p4 #ddh4 ,footnote #bc3 ,see ,%eets #ga ,n4,w41 #gb ,n4,e41 #ha ,n4,e4 & ,s4,e4 & #hb ,s4,w4 ( ! ,geological ,survey ( ,engl& & ,wales4 ,?\gh ! toad/ones 7 believ$ to =m def9ite plat=ms among ! lime/one /rata1 & ?us to be capable ( be+ us$ z reliable horizons 9 ! m9]al fields ( ,d]by%ire1 !y appe> to h be5 g5]ally reg>d$ z intrusive %eets l ! ,:9 ,sill ( ! nor?4 ,?us ,de la ,be*e 9 8 ,manual ( ,geology1 giv+ a summ>y ( :at 0 kn[n at ! "t reg>d+ int]calat$ igne\s rocks1 rem>ks ) reg>d to ! ,d]by%ire toad/ones t !y may f all analogy be consid]$ to h be5 inject$ among ! lime/ones :i* w\ld be easily sep>at$ by ! =ce ( ! intrud$ igne\s mat]ial4#bd ,b ! same obs]v]1 aft] 8 exp]i5ce among ! anci5t volcanic rocks ( ,devon%ire1 came fully to recognize ! pro(s ( contemporane\s outfl[ among ! ,d]by%ire toad/ones4 ,9 8 subsequ5tly publi%$ ,geological ,obs]v]1 he describ$ ! toad/ones z subm>9e lavas t _h be5 p\r$ out ov] ! floor ( ! sea 9 :i* ! ,c>bonif]\s ,lime/one 0 deposit$1 & _h be5 aft]w>ds cov]$ up "u fre% deposits ( lime/one4#be ,x is rem>kable1 h[ev]1 t he specially comm5ts on ! abs5ce1 z he believ$1 ( any contemporane\sly eject$ a%es & lapilli1 su* z occur 9 ,devon%ire4 ,t true tuffs or volcanic a%es are associat$ ) ! toad/ones 0 notic$ by ,jukes 9 #ahfa1bf & aft]w>ds by ! ,geological ,survey4#bg ,s9ce t "t geologi/s h g5]ally recogniz$ ^! ,d]by%ire igne\s rocks z truly contemporane\s int]calations4 ,b v little has rec5tly be5 writt5 on ! /ructure ( ! di/rict1 our in=mation reg>d+ x be+ /ill bas$ ma9ly on ! e>ly obs]vations ( ,fairey & ! mapp+ ( ! ,geological ,survey4 ,footnote #bd3 ,manual1 #crd edit4 #ahcc1 p4 #dfb4 ,footnote #be3 ,geological ,obs]v] 7#ahea71 pp4 #fdb-fde4 ,footnote #bf3 ,/ud5t's ,manual ( ,geology1 #bnd edit4 7#ahfc71 p4 #ebc4 ,= a g5]al rsum ( ! pro(s ( contemporaneity furni%$ by ! toad/ones1 see ,! ,geology ( ,nor? ,d]by%ire1 by ,messrs4 ,a4 ,h4 ,gre5 & ,a4 ,/rahan 7,memoirs ( ! ,geological ,survey1 #bnd edit4 7#ahhg71 p4 #abc74 ,footnote #bg3 ,9 ! fir/ edition ( ! ,memoir on ! ,geology ( ,nor? ,d]by%ire1 publi%$ 9 #ahei1 ! au?ors ( :i* 7 ,messrs4 ,a4 ,h4 ,gre51 ,c4 le ,neve ,fo/] & ,j4 ,r4 ,dakyns4 ,! subject1 h[ev]1 has n[ be5 resum$ by ,mr4 ,h4 ,arnold ,bemrose1 :o 9 #ahid1 aft] a prolong$ /udy ( ! petrography ( ! rocks1 communicat$ ! results ( 8 rese>*es to ! ,geological ,society4#bh ,9 8 excell5t pap]1 to :i* ,i %all imm$iately make full] ref]5ce1 he m5tions ! localities at :i* lava-=m & fragm5tal rocks may be obs]v$1 b does n ent] on ! discussion ( ! geological /ructure ( ! region or ( ! hi/ory ( ! volcanic eruptions4 ,be=e ! ann\ncem5t ( 8 pap]1 he>+ t ,i propos$ to make = ! fir/ "t a rapid trav]se ( ! toad/one di/rict1 = ! purpose ( acqua9t+ myself ) ! rocks on ! gr\nd1 he k9dly (f]$ to conduct me ov] x4 ,my *ief object1 besides t ( see+ ! g5]al nature ( ! volcanic ph5om5a ( ! region1 0 to exam9e m p>ticul>ly ! areas ( ! volcanic fragm5tal rocks1 ) ! view ( discov]+ :e!r among !m "s rema9s might n be f\nd ( ! actual v5ts ( dis*>ge4 ,9 ?is se>* ,i 0 entirely successful4 ,aid$ by ,mr4 ,bemrose's intimate k ( ! gr\nd1 ,i 0 enabl$ to visit 9 rapid succession ^? tracts :i* seem$ mo/ likely to furni% ! requir$ evid5ce1 & 9 a few days 0 =tunate en\gh to obta9 pro(s ( six or sev5 di/9ct v5ts1 rang+ f ! extreme nor!rn to ! fur!/ s\!rn b\nd>y ( ! volcanic di/rict4 ,mr4 ,bemrose has und]tak5 to cont9ue ! inve/igation1 & w1 ,i tru/1 "w out ! detail$ /ratigraphy ( ! ,c>bonif]\s ,lime/one s z ev5tually to furni% an exhau/ive n>rative ( ! :ole volcanic hi/ory ( ,d]by%ire4 ,mean:ile no adequate acc\nt ( ! area c be giv54 ,b ,i w "h /ate all ! ess5tial facts :i* up to ! pres5t "t h be5 asc]ta9$4 ,footnote #bh3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 l4 7#ahid71 p4 #fjc4 #a4 ,,! ,,rocks ,,erupt$4--,mr4 ,allport has describ$ ! microscopic "* ( "s ( ! toad/ones1#bi & fur!r details h be5 suppli$ by ,mr4 ,teall4#cj ,! fulle/ acc\nt ( ! subject1 h[ev]1 is t giv5 by ,mr4 ,bemrose 9 ! pap] above ref]r$ to4 ,?is obs]v] di/+ui%es ! lava-=m f ! fragm5tal rocks1 & gives ! m9ute *>act]s ( ea* s]ies4 ,he does n1 h[ev]1 sep>ate true int]/ratifi$ lavas f inject$ sills1 nor ! b$d$ tuffs f ! co>se agglom]ates :i* fill up ! v5ts4 ,^! di/9ctions are obvi\sly requir$ 9 ord] t ! true nature & sequ5ce ( ! mat]ials 9 ! volcanic eruptions may be trac$1 & t ! ph5om5a exhibit$ 9 ,d]by%ire may be br\ght into comp>ison ) ^? f\nd 9 o!r ,c>bonif]\s di/ricts4 ,b to e/abli% !m satisfactorily ! :ole region mu/ be c>efully re-exam9$ & ev5 to "s ext5t re-mapp$4 ,footnote #bi3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxx4 7#ahgd71 p4 #ebi4 ,footnote #cj3 ,briti% ,petrography1 p4 #bji4 ,! lavas 7includ+1 9 ! meantime1 %eets :i* !re c be little d\bt are sills7 %[ ?ree ma9 types ( m9ute /ructure & composition1 :i* are discrim9at$ by ,mr4 ,bemrose z--7a7 ,oliv9e-dol]ites2 ^!1 ! mo/ abundant ( ! s]ies1 consi/ ( augite 9 gra9s1 oliv9e 9 idiomorphic cry/als1 plagioclase giv+ la?-%ap$ & tabul> sections1 & magnetite or ilm5ite 9 rods & gra9s2 7b7 ,ophitic oliv9e-dol]ites1 consi/+ ( augite 9 ophitic plates =m+ ! gr\ndmass1 9 :i* are imb$d$ idiomorphic oliv9e1 plagioclase 7(t5 giv+ l>ge la?-%ap$ sections & magnetite or ilm5ite72 7c7 ,oliv9e-basalts2 ^! rocks are di/+ui%$ by conta9+ cry/als ( augite & oliv9e 9 a gr\ndmass ( small felsp>-la?s1 granul> augite & magnetite or ilm5ite1 ) v little int]/itial matt]4 ,!y h be5 notic$ only 9 two ( ! outcrops ( toad/one4 ,! fragm5tal rocks h be5 %[n by ,mr4 ,bemrose to cov] a mu* m ext5sive space ?an _h be5 previ\sly suppos$4 ,he has f\nd !m to be di/+ui%$ by an abundance ( lapilli v>y+ f m9ute fragm5ts up to pieces ab\t ! size ( a pea1 & compos$ ( a mat]ial t diff]s 9 /ructure f ! dol]ites & basalts ) :i* ! tuffs are associat$4 ,^! lapilli consi/ l>gely ( a glassy base m or less alt]$1 :i* is g5]ally f9ely vesicul> & encloses abundant skeleton cry/als & cry/allites4 ,! tuffs ?us v closely resemble "s ( ! ,c>bonif]\s basic tuffs ( ,fife1 already ref]r$ to 7vol4 i4 p4 #dbb71 & l ^! !y include abundant blocks ( dol]ite & basalt4 #b4 ,,geological ,,/ructure ,,( ,,! ,,toad/one ,,di/rict4--,z ! volcanic rocks ( ,d]by%ire lie among ! ,c>bonif]\s ,lime/ones ( a broad anticl9al dome1 !y are only expos$ :]e ^! lime/ones h be5 suffici5tly d5ud$1 & z ! base ( ! lime/ones is n[h]e laid b>e1 ! l[e/ p>ts ( ! volcanic s]ies may be conceal$4 ,ov] ! tract :]e ! toad/ones c be exam9$ !y appe> z b&s regul>ly int]calat$ ) ! lime/ones1 b v>y+ 9 ?ickness 9 ! c\rse ( _! outcrops4 ,z !y are prone to decay1 !y usually =m smoo? grassy slopes betwe5 ! lime/one sc>ps1 ?\gh isolat$ blocks ( ! dull br[n igne\s rocks may (t5 be se5 protrud+ f ! surface4 ,n[ & !n a h>d] b$ ( toad/one caps a hill1 & ?us =ms a prom95t feature 9 ! l&scape1 b z a rule ^! igne\s b&s play no di/+ui%+ "p 9 ! sc5]y1 & are inde$ less conspicu\s ?an ! :ite esc>pm5ts ( lime/one :i* ov]lie !m4 ,x 0 ! op9ion ( ! old] geologi/s t ?ree di/9ct plat=ms ( toad/one ext5d )\t break ?r\gh\t ! di/rict1 & subdivide ! lime/ones into f\r portions4 ,b ?is op9ion does n seem to h be5 bas$ on good evid5ce ei!r ( sequ5ce or ( cont9uity4 ,v>i\s facts 7 br\ght =w>d by ! (fic]s ( ! ,geological ,survey to %[ t ! suppos$ p]si/5ce ( ! ?ree plat=ms ( toad/one did n really exi/1 b t ^! %eets ( igne\s mat]ial are f\nd at diff]5t spots on v diff]5t horizons1 & are ( limit$ horizontal range4#ca ,s f> z my own limit$ obs]vations g1 !y entirely corroborate ?is view4 ,!re c be little d\bt1 ,i ?9k1 t ! id5tity ( c]ta9 outcrops ( toad/one has be5 assum$1 & ! assumption has be5 c>ri$ ?r\gh\t ! di/rict4 ,! tru? is t ! numb] ( successive plat=ms on :i* igne\s mat]ials appe> w nev] be satisfactorily det]m9$ until ! /ratigraphy ( ! ,d]by%ire ,c>bonif]\s ,lime/one is work$ out 9 detail4 ,:5 ! successive memb]s ( ?is great calc>e\s =mation h be5 id5tifi$ by li?ological & palontological *>act]s ov] ! di/rict1 x w be easy to allocate ea* outcrop ( toad/one to its true geological horizon4 ,:5 ?is lab\r has be5 complet$1 x w probably be f\nd t in/ead ( ?ree1 !re h be5 _m dis*>ges ( volcanic mat]ial dur+ ! deposition ( ! lime/one s]ies2 t ^! h proce$$ f num]\s small v5ts1 & t !y are all ( comp>atively re/rict$ horizontal ext5t4 ,su* a detail$ exam9ation w also det]m9e h[ f> ! toad/ones include v]itable sills1 & on :at horizons ^! intrusive %eets h be5 inject$4 ,footnote #ca3 ,geol4 ,surv4 ,mem4 on ,nor? ,d]by%ire1 by ,messrs4 ,gre5 & ,/rahan 7#ahhg71 p4 #ajd4 ,9 ! meantime1 we "k t ! l[e/ visible b&s ( toad/one are und]la9 by sev]al hundr$ feet ( lime/one1 ?us prov+ t ! e>lie/ kn[n volcanic explosions took place ov] ! floor ( ! ,c>bonif]\s ,lime/one sea1 aft] at lea/ #gjj or #hjj feet ( calc>e\s s$im5t _h accumulat$ !re4 ,! late/ traces ( volcanic activity are f\nd 9 a "p ( ! ,yor$ale gr\p ( %ales & lime/ones :i* =m ! upp]mo/ memb] ( ! ,c>bonif]\s ,lime/one ( ?is region4 ,b x is n q cle> :e!r ! vesicul> diabase f\nd !re is int]/ratifi$ or intrusive4 ,c]ta9ly no contemporane\s tuffs h yet be5 f\nd among ! ,yor$ale rocks1 nor 9 any high] subdivision ( ! ,c>bonif]\s sy/em1 ?\gh co>se agglom]ates m>k+ ! position ( v5ts d trav]se ! ,yor$ale gr\p at ,kniveton4 ,x may be rem>k$ t 9 ! di/rict ov] :i* ! toad/ones c be se51 two areas are recognizable1 9 ea* ( :i* ! exposures ( ! igne\s rocks are num]\s1 :ile betwe5 !m lies an int]v5+ tract :]e9 !re is h>dly any visible outcrop ( ^! rocks4 ,! nor!rn & mu* ! m ext5sive area /ret*es f ,ca/leton to ,%eldon1 :ile ! s\!rn spreads f ,w9/] to ,kniveton4 ,?is di/ribution n improbably po9ts to ! orig9al position ( ! v5ts1 & indicates a nor!rn m num]\s gr\p ( volcanic orifices1 & a s\!rn tract :]e ! v5ts 7 few]1 or at lea/ spread _! dis*>ges ov] a m limit$ space4 #c4 ,,! ,,v5ts4--,x _h always appe>$ to me s+ul> t1 9 gr\nd s deeply tr5*$ by valleys z ! toad/one di/rict ( ,d]by%ire1 no trace _h be5 recogniz$ ( any bosses or necks f :i* ^! volcanic %eets might h be5 erupt$4 ,x is true t 9 m9+ op]ations masses ( toad/one _h be5 p5etrat$ to a consid]able dep? )\t _! bottom be+ rea*$1 & ! sugge/ion _h be5 made t 9 su* cases a %aft may actually h be5 sunk on "o ( ! v5ts ?r\gh :i* ! toad/one came up4#cb ,"o in/ance 9 p>ticul> 0 cit$ :]e1 at ,black ,hillock1 on ,tideswell ,moor1 close to ,peak ,=e/ ,village1 a mass ( toad/one 0 n cut ?r\gh1 ?\gh pi]c$ to a dep? ( #ajj fa?oms4 ,9 t neighb\rhood1 h[ev]1 sev]al ( ! %eets ( eruptive mat]ial are probably sills1 & ! %aft at ,black ,hillock may h be5 sunk ^u ! pipe or ve9 t suppli$ "o or m ( ^! intrusive %eets4 ,footnote #cb3 ,geol4 ,surv4 ,mem4 on ,nor? ,d]by%ire1 p4 #acd4 ,x 0 !re=e ) no little int]e/ t ,i detect$ a s]ies ( v5ts at f\r sep>ate localities1 viz4 ,ca/leton1 ,grange ,mill1 ,hopton1 & ,kniveton ,wood4 ,i h no d\bt t a m ext5d$ se>* w br+ o!rs to light4 ,^? obs]v$ by me are all fill$ ) co>se agglom]ate1 ! blocks 9 :i* are mo/ly compos$ ( diff]5t lavas1 sometimes ) ! addition ( blocks ( lime/one1 :ile ! matrix consi/s ma9ly ( lapilli ( basic devitrifi$ glass4 ,! mo/ typical examples =m a gr\p ( two1 possibly ?ree1 v5ts :i* rise into two isolat$1 smoo?1 grassy dome-%ap$ hills at ,grange ,mill1 five miles we/ f ,matlock ,ba?4#cc ,9 ext]nal =m & col\r1 ^! em95ces pres5t a contra/ to ! sc>p$ slopes ( lime/one ar\nd !m4 ,!y at once recall ! cont\rs ( _m ( ! volcanic necks 9 ,c5tral ,scotl&4 ,on exam9ation x is f\nd t ! mat]ial compos+ !m is a dull gre5 agglom]ate1 ! matrix ( :i* is a compact sub/ance wea!r+ sph]oidally1 & full ( small lapilli ( m9utely vesicul> diabase4 ,! l>g] /ones consi/1 = ! mo/ "p1 ( v>i\s vesicul> dol]ites or diabases1 toge!r ) "s pieces ( lime/one & occasionally l>ge blocks ( ! latt] rock1 alt]$ into a sac*>oid condition4 ,two dykes ( dol]ite or basalt trav]se ! m>g9 ( ! l>g] v5t4 ,footnote #cc3 ,?is is ,mr4 ,bemrose's outcrop1 ,no4 #df1 op4 cit4 p4 #fcc4 ,! /eep sides ( ^! agglom]ate domes rise f ! l[ gr\nd ar\nd !m to a height ( #ajj to #ahj feet1 _! summits be+ a little m ?an #ijj feet above ! sea4 ,! small] neck is ne>ly circul>1 & measures ab\t #ajjj feet 9 diamet]4 ,! l>g] mass is less regul> 9 %ape1 & is prolong$ into su* a bulge on ! s\?-ea/ z to sugge/ t its prolongation 9 t direction may really m>k ! position ( a ?ird & mu* small] v5t contigu\s to x4 ,! long] diamet] ( ! l>g] mass is #bcjj & ! %ort] #acjj feet4 ,illu/ration3 ,fig4 #agh4--,view ( two volcanic necks 9 ! ,c>bonif]\s ,lime/one s]ies1 at ,grange ,mill1 five miles we/ ( ,matlock ,ba?1 f ! nor?4 ,on ! s\? & we/ sides1 ! surr\nd+ lime/one c be trac$ up to )9 a few feet ( ! edge ( ! agglom]ate1 & its /rata are !re f\nd to be mu* jumbl$ & brok51 :ile _! texture is r m cry/all9e ?an usual1 ?\gh n sac*>oid4 ,! two necks are sep>at$ by a n>r[ valley 9 :i* no rock is visible4 ,_! opposite declivities meet at ! bottom ( ?is holl[1 & are s def9itely m>k$ (f t1 ev5 9 ! abs5ce ( pro( t !y are disjo9$ by int]v5+ lime/one1 !re c be little hesitation 9 reg>d+ ea* hill z m>k+ a di/9ct v5t4 ,a wid] valley ext5ds along ! ea/]n base ( ! necks1 & slopes upw>d on its ea/ side until x is cr[n$ by a long esc>pm5t ( lime/one1 :i* rea*es a height ( #ajjj feet above ! sea1 or ab\t #ajj feet above ! valley f :i* x rises4 ,un=tunately1 ! bottom & slopes ( ?is depression are ?ickly cov]$ ) soil1 b at "o or two places debris ( f9e tuff may be obs]v$1 & at ! nor!rn & s\!rn ends ( ! holl[ well-b$d$ gre5 & r$di% tuff appe>s1 dipp+ g5tly bel[ ! lime/one esc>pm5t4 ,?is b& ( volcanic detritus evid5tly und]lies ! lime/one1 & =ms mo/ ( ! g5tle slope on ! ea/ side ( ! valley4 ,x may be f #gj to #ajj feet ?ick4 ,t x 0 dis*>g$ f "o or bo? ( ! necks seems tol]ably cle>4 ,its mat]ial resembles t =m+ ! matrix ( ! agglom]ate4 ,! g5]al arrangem5t ( ! rocks at ?is int]e/+ locality is repres5t$ 9 ,fig4 #agi1 :i* is r$uc$ f my survey on ! scale ( six in*es to a mile4 ,a section across ! small] v5t w\ld %[ ! /ructure repres5t$ 9 ,fig4 #ahj4 ,illu/ration3 ,fig4 #agi4--,plan ( necks & b$d$ tuff at ,grange ,mill1 five miles we/ ( ,matlock ,ba?4 ,illu/ration3 ,fig4 #ahj4--,section across ! small] volcanic neck & ! /ratifi$ tuff 9 ,c>bonif]\s ,lime/one1 ,grange ,mill4 #a4 ,lime/one2 #b4 ,/ratifi$ tuff int]calat$ among ! lime/ones2 #c4 ,agglom]ate4 ,?is gr\p ( v5ts lies 9 ! s\!rn ( ! two tracts ( ! volcanic di/rict4 ,9 ! nor!rn tract a mass ( agglom]ate pi]ces ! base ( ! lime/one esc>pm5t ab\t a qu>t] ( a mile we/ f ! entrance to ! ,peak ,cav]n at ,ca/leton4#cd ,x is rudely semicircul> 9 area1 /ret*+ d[n ! slope until its nor!rn ext5sion is lo/ "u ! l[] gr\nd4 ,! agglom]ate is n well expos$1 b x c be se5 to be a gre51 granul> crumbl+ rock1 made up 9 great "p ( m9utely vesicul> lapilli1 enclos+ blocks ( v>i\s diabases two feet long or m4 ,f ! abrupt way 9 :i* ?is agglom]ate rises ?r\gh ! lime/one1 !re c be little d\bt t x m>ks ! position ( "o ( ! volcanic v5ts ( ! "t4 ,z x /&s on ! extreme nor!rn v]ge ( ! lime/one area1 ! gr\nd fur!r nor? be+ cov]$ ) ! ,yor$ale rocks & ,mill/one ,grit1 x is ! mo/ nor!rly ( ! :ole volcanic di/rict4 ,footnote #cd3 ,?is is outcrop ,no4 #a ( ,mr4 ,bemrose's pap]1 p4 #fbe4 ,along ! s\!rn m>g9 ( ! lime/one c\ntry a gr\p ( agglom]ate masses probably m>ks ano!r *a9 ( v5ts4 ,^! are specially int]e/+1 inasmu* z !y abut on ! ,yor$ale s]ies1 & may ?us be look$ ^u z among ! late/ ( ! volcanic *imneys4 ,"o ( !m is se5 at ,hopton1#ce :]e along ! side ( ! road a good section is expos$ ( co>se tumultu\s agglom]ate1 hav+ a dull gre5 matrix1 compos$ ( gre51 br[n1 & black1 m9utely cellul>1 basic1 devitrifi$1 glassy lapilli1 %[+ "u ! microscope abundant microlites & cry/als or calc>e\s pseudomorphs ( oliv9e1 augite1 & felsp>1 & mu* magnetite du/4 ,?r\gh ?is matrix are di/ribut$ blocks ( slaggy basalt & dol]ite4 ,an int]e/+ feature ( ?is mass is ! occurr5ce 9 x ( "s ve9s1 two or ?ree in*es broad1 ( a compact black porphyritic basalt4 ,i did n trace ! relations ( ?is agglom]ate to ! /ratifi$ rocks ar\nd x4 ,b its int]nal /ructure & composition m>k x out z a true neck4 ,x ext5ds1 accord+ to ! ,geological ,survey map1 = ab\t half a mile along ! edge ( ! lime/one1 & is repres5t$ z be+ sep>at$ by two faults f ! ,yor$ale s]ies imm$iately to ! s\?4 ,s long z ! belief is ent]ta9$ t ! toad/ones are contemporane\s outfl[s ( lava ly+ on c]ta9 def9ite horizons1 f> bel[ ! summit ( ! lime/ones1 ! position ( ! ,hopton agglom]ate is only explicable on ! assumption ( "s dislocation by :i* ! ,yor$ale %ales h be5 br\ght d[n aga9/ x4 ,b :5 we realize t ! rock is an un/ratifi$ agglom]ate1 probably m>k+ ! place ( a volcanic v5t1 & !re=e ris+ transgressively ?r\gh ! surr\nd+ /rata1 ! necessity = a fault is remov$1 or if a fault is ins]t$ its exi/5ce %\ld be ju/ifi$ on o!r evid5ce ?an ! relations ( ! igne\s rock to ! surr\nd+ /rata4 ,footnote #ce3 ,geol4 ,surv4 ,mem4 ,nor? ,d]by%ire1 p4 #bd4 ,?is is outcrop ,no4 #ec ( ,mr4 ,bemrose's pap]1 p4 #fce4 ,f\r miles to ! s\?-we/ ( ,hopton1 on ! slope ( ! hill at ,kniveton ,wood1 ano!r rem>kable mass ( agglom]ate =ms a r\nd$ ridge betwe5 ! two =ks ( a small /ream4#cf ,its granul> matrix1 l t ( ! o!r necks1 consi/s ( lapilli ( m9utely vesicul> basic glassy lava or pumice1 & encloses l>ge & small r\nd$ blocks ( f9ely cellul> basalt & pieces ( lime/one4 ,! rock is un/ratifi$1 & 9 all respects resembles t ( ord9>y ,c>bonif]\s necks 9 ,scotl&4 ,its relations to ! ,yor$ale rocks are laid b>e 9 ! *annels ( ! /reamlets4 ,!re ! %ales & ?9 lime/ones may be se5 mu* brok5 & plicat$1 _! curv$ & fractur$ ends /rik+ directly at ! agglom]ate4 ,!y may be trac$ to )9 a y>d ( ! agglom]ate4 ,on ! ,geological ,survey map ! igne\s rock is repres5t$ z b\nd$ by two p>allel faults4 ,b ,i h>dly ?9k t ?is explanation suffices to acc\nt = ! relations ( ! rocks & _! rem>kable b\nd>y-l9e1 :i* seems to me to be und\bt$ly ! wall ( a volcanic v5t4 ,to ! ea/ ( ! /reams1 ano!r mass ( agglom]ate may m>k ano!r neck1 :ile to ! nor?1 a ?ird deta*$ area ( ! same k9d ( rock1 ris+ among ! lime/ones1 may be reg>d$ z likewise a di/9ct mass4 ,at ?is locality1 !re=e1 !re are two1 possibly ?ree1 v5ts4 ,"o ( ^!1 f ! way 9 :i* x cuts across ! ,yor$ale %ales & lime/ones1 is to be assign$ to a "t lat] ?an ! old] "p ( ! ,yor$ale s]ies1 & ?us1 l ! ,hopton mass1 x indicates t 9 ! s\? ( ! volcanic area eruptions did n cease ) ! close ( ! deposition ( ! ?ick lime/ones1 b 7 prolong$ ev5 into ! "t ( ! ,yor$ale rocks4 ,footnote #cf3 ,outcrop ,no4 #ef1 p4 #fch ( ,mr4 ,bemrose's pap]4 ,a fur!r pro( ( ! late age ( ^! s\!rn pat*es ( volcanic mat]ial is %[n by two b&s ( vesicul> toad/one 9 ! ,yor$ale s]ies1 a little s\? f ! village ( ,kniveton4 ,^! rocks are trac$ on ! ,survey ,map1 & are %[n 9 a diagram 9 ! ,memoir1 :]e _! position is s\ght to be expla9$ by a sy/em ( p>allel fault+4#cg ,i 0 able to trace ! actual contact ( ! we/]n b& ) ! /rata und]nea? x1 & satisfi$ myself t !re is no fault at ! junction4 ,! igne\s mat]ial is regul>ly b$d$ ) ! ,yor$ale %ales & lime/ones4 ,ei!r1 !re=e1 ^! b&s are int]calat$ lava-/reams or intrusive sills4 ,if m]e vesicul> /ructure 7 en\gh to di/+ui% true outfl[+ lavas1 !n !re c\ld be no d\bt ab\t ^! ,kniveton rocks4 ,b ?is /ructure is f\nd 9 s _m ,c>bonif]\s sills1 p>ticul>ly 9 ^? ?9 %eets :i* h be5 inject$ into coals & black %ales1 t its pres5ce is f> f decisive4 ,! vesicles 9 ! ,kniveton rocks are small & pea-l1 tol]ably uni=m 9 size & %ape1 & cr[d$ toge!r4 ,!y are ?us n at all l ! irregul> cavities 9 ! ord9>y cellul> & scoriace\s lavas ( ! toad/one s]ies4 ,footnote #cg3 ,op4 cit4 p4 #hg4 ,:e!r or n ! "q ( _! true relations be ev] satisfactorily settl$1 ^! ,kniveton b&s are c]ta9ly y\ng] ?an ! l[] portion ( ! ,yor$ale gr\p4 ,_! evid5ce ?us agrees ) t ( ! s\!rn agglom]ates 9 %[+ t ! volcanic activity ( ?is region 0 cont9u$ ev5 aft] ! ?ick calc>e\s masses ( ! ,c>bonif]\s ,lime/one s]ies _h ceas$ to be deposit$4 ,besides ! six necks to :i* ,i h ref]r$1 a rock 9 ,emb] ,lane1 above ,bonsall1 probably belongs to ano!r v5t4#ch ,x is p>ticul>ly int]e/+ f ! great prepond]ance ( lime/one fragm5ts 9 x4 ,! volcanic explosions at ?is locality broke up ! already solidifi$ lime/ones on ! floor ( ! ,c>bonif]\s ,lime/one sea1 & /rew$ !m ar\nd1 m+l$ ) volcanic blocks & du/ ( ! prevail+ type4 ,footnote #ch3 ,?is is outcrop ,no4 #ci ( ,mr4 ,bemrose's pap]1 p4 #fcb4 ,:5 ! di/rict has be5 m c>efully se>*$1 o!r c5tres ( eruption w no d\bt be discov]$4 ,x may !n be possible to depict ! di/ribution ( ! active v5ts1 & to connect ) !m ! outfl[ ( ! b$d$ lavas4 ,s f> z ,i h be5 able to asc]ta91 !re are no necks ( dol]ite or basalt1 ?\gh1 z ,i h %[n1 dykes or ve9s ( molt5 rock are occasionally to be f\nd 9 ! agglom]ates ( ! necks4 #d4 ,,! ,,lavas ,,& ,,tuffs4--,i h ref]r$ to ! op9ion ( ,de la ,be*e t ! toad/ones ( ,d]by%ire 7 p\r$ out z lava-/reams )\t any accompany+ fragm5t>y dis*>ges1 & to ! correction ( ?is op9ion by ! subsequ5t obs]vations ( ,jukes & ( ! ,geological ,survey4 ,b ?\gh ! exi/5ce ( int]b$d$ tuffs has long be5 kn[n1 x 0 n until ,mr4 ,bemrose's m c>eful scrut9y t ! relative importance ( ! tuffs among ! lavas 0 fir/ indicat$4 ,he has %[n t a numb] ( ! b&s mapp$ z toad/one are tuffs1 & he has discov]$ o!r b&s ( tuff :i* h n yet be5 plac$ on any publi%$ map4 ,9 exam9+ ! outcrops ( ! v>i\s toad/ones ( ,d]by%ire we le>n t "s ( !m are lavas )\t tuffs1 probably includ+ a numb] ( b&s1 :i* are really sills2 t o!rs are =m$ ( bo? lavas & tuffs1 & t a ?ird type %[s only b$d$ tuff4 ,ea* ( ^! developm5ts w des]ve sep>ate description4 ,b be=e ent]+ into details1 we may take note ( ! v>y+ ?icknesses ( ! diff]5t toad/ones :i* h be5 det]m9$ by obs]vation at ! surface or by measurem5t und]nea? 9 m9+ op]ations4 ,9 "s cases a di/9ct b& ( toad/one1 sep>at$ by _m feet or y>ds ( lime/one f ! next b&1 & !re=e s]v+ to m>k a sep>ate volcanic dis*>ge1 may n exce$ a y>d or two 9 total ?ickness1 & f t m9imum may swell out to #ajj feet4 ,! majority ( ! b&s probably range betwe5 #ej & #ajj feet 9 ?ickness4 ,9 "o exceptional case at ,snitt]ton1 a mass ( black/one is said to h be5 prov$ to be #bdj feet ?ick1 b ?is rock may n improbably h be5 a sill4#ci ,! true contemporane\s int]calations seem to be g5]ally less ?an #ajj feet 9 ?ickness4 ,footnote #ci3 ,a diff]5ce is made by ! m9+ community betwe5 toad/one & :at is call$ black/one4 ,! =m] "n appe>s to be re/rict$ to ! amygdaloidal gre5 & g5]ally m or less decay$ lavas2 ! latt]1 s f> z ,i c le>n1 is appli$ to ! d>k1 m solid & cry/all9e rocks4 ,if ?is di/9ction be well f\nd$ ! "o "n may p]haps s]ve to m>k ! op5 cellul> lavas1 ! o!r ! m compact1 d>k1 & heavy intrusive %eets4 7a7 ,lavas )\t ,tuffs4--,examples occur ( %eets ( toad/one :i* consi/ entirely ( contemporane\sly eject$ diabase1 basalt or dol]ite4 ,?is rock is !n dull gre5 or br[n 9 col\r1 m or less e>?y 9 texture1 & irregul>ly amygdaloidal4 ,! vesicles are extremely v>i$ 9 size1 =m & di/ribution1 sometimes exp&+ until ! rock becomes a slaggy mass4 ,a c5tral m solid portion betwe5 a scoriace\s bottom & top may sometimes be obs]v$1 z at ! ,great ,rocks ,qu>ry1 ,peak ,=e/ ,limeworks 7,fig4 #aha74 ,9 ?is1 z 9 o!r examples1 a rem>kably hummocky & unev5 surface ( lime/one lies bel[ ! igne\s b&1 ! calc>e\s rock pres5t+ knobs & ridges1 sep>at$ by cauldron-%ap$ cavities & clefts1 "s ( :i* are sev]al y>ds deep4 ,^! inequalities are fill$ 9 & cov]$ ov] ) a s(t yell[ & br[n clay1 v>y+ up to ?ree or f\r feet ?ickness1 & pass+ upw>ds into ! m solid toad/one4 ,!re c h>dly be any d\bt t ?is s+ul>ly unev5 lime/one surface is due to ! solv5t action ( wat] ly+ betwe5 ! lime/one & ! some:at imp]vi\s toad/one above1 & t ! clay repres5ts p>tly ! insoluble residue ( ! calc>e\s rock1 b *iefly ! result ( ! action ( ! infiltrat+ wat] on ! bottom ( ! igne\s b&4#dj ,footnote #dj3 ,geological ,survey ,memoir on ,nor? ,d]by%ire1 p4 #bj & footnote4 ,illu/ration3 ,fig4 #aha4--,section ( vesicul> & amygdaloidal diabase re/+ on ,c>bonif]\s lime/one1 ,peak ,=e/ ,limeworks1 ,great ,rocks ,qu>ry4 #a4 ,lime/one ) a surface dissolv$ into cauldron-l holl[s2 #b4 ,rott5 yell[ & br[n clay result+ f decomposition ( toad/one & :ite clay f ! solution ( ! lime/one--sometimes ?ree or f\r feet ?ick2 #c4 ,toad/one1 a diabase ) highly slaggy base4 ,illu/ration3 ,fig4 #ahb4--,view ( ! sup]position ( ,c>bonif]\s lime/one ^u toad/one1 ,rav5's ,tor1 ,mill]sdale 7l5g? ab\t #ajj feet74 #a4 ,toad/one2 #b4 ,lime/one2 f1 ,fault4 ,junctions ( ! upp] surfaces ( ! lava-%eets ) ! ov]ly+ lime/one %[ t ! igne\s mat]ial sometimes assum$ hummocky =ms1 :i* ! calc>e\s deposits gradually ov]spread & cov]$4#da ,a good example ( ?is k9d may be obs]v$ by ! roadside at ! foot ( ,rav5's ,tor1 ,mill]sdale4 ,z %[n 9 ! subjo9$ figure1 ! lime/one has "h be5 worn into a cave1 ! floor ( :i* is =m$ by ! toad/one4 ,! latt] rock1 ( ! usual dull gre51 slaggy & amygdaloidal "*1 is cov]$ imm$iately by ! lime/one1 b ,i did n obs]ve any fragm5ts ( ! toad/one1 nor any trace ( a%y mat]ials 9 ! ov]ly+ calc>e\s /rata4 ,?is section %[s t aft] ! outfl[ ( ! lava1 ! s$im5tation ( ! lime/one 0 quietly resum$1 & ! igne\s int]ruption 0 entirely buri$4 ,footnote #da3 ,comp>e ,de la ,be*e1 ,geological ,obs]v]1 pp4 #eei1 #efj1 & ,nor? ,d]by%ire ,memoir1 p4 #abc4 ,9 "s cases !re is evid5ce ( m ?an "o outfl[ ( lava 9 ! same b& ( toad/one4 ,jukes believ$ t ea* b& 0 ! result1 n ( "o simultane\s ejection ( igne\s matt]1 b ( sev]al1 proce$+ f diff]5t foci unit+ toge!r to =m "o b&1 & he f\nd t ne> ,buxton1 two solid b$s ( toad/one c\ld be se5 to h proce$$ f opposite qu>t]s t[>ds ea* o!r )\t ov]lapp+4#db ,footnote #db3 ,/ud5t's ,manual ( ,geology1 #b;d edit4 7#ahfb71 p4 #ebc4 ,9 ,mill]sdale ! au?ors ( ! ,geological ,survey ,memoir on ,nor? ,d]by%ire obs]v$ t a b& ( toad/one ab\t #ajj feet ?ick %[$ six di/9ct divisions1 :i* !y 7 dispos$ to reg>d z m>k+ s _m sep>ate b$s4#dc ,9 ,tideswell ,dale1 on ! we/ side ( ! valley1 imm$iately to ! s\? ( ! old toad/one qu>ry1 two b&s ( toad/one are se5 to be sep>at$ by a few y>ds ( lime/one4 ,footnote #dc3 ,op4 cit4 p4 #ai4 7b7 ,lavas ) ,tuffs4--,x w probably be f\nd t 9 _m1 if n 9 mo/ cases1 ! outfl[ ( lava 0 prec$$1 accompani$ or foll[$ by fragm5tal dis*>ges4 ,z f> back z #ahfa1 ,jukes notic$ t a toad/one b&1 ab\t #ej feet ?ick1 ne> ,buxton consi/$ ( two solid b$s ( lava ) b$s ( purple & gre5 a%1 greatly decompos$ into clay1 bo? above & bel[ ea* b$ & betwe5 ! two4#dd ,footnote #dd3 ,op4 cit4 p4 #ebc4 ,illu/ration3 ,fig4 #ahc4--,section at lime-kiln1 s\? ( ,viaduct1 ,mill]sdale ,/ation4 ,an int]e/+ section1 %[+ ?is int]calation ( ! two k9ds ( mat]ial is expos$ at ! lime-kilns beyond ! s\!rn end ( ! railway viaduct at ,mill]sdale ,/ation4 ,ov] a mass ( solid blue lime/one 7#a 9 ,fig4 #ahc7 lies a b& ( bright yell[ & br[n clay 7#b71 v>y+ f six in*es to two feet 9 ?ickness4 ,?is may be comp>$ ) ! clay f\nd above ! lime/one at ,peak ,=e/ 7,fig4 #aha74 ,b x is probably a lay] ( highly decompos$ tuff4 ,x is succe$$ by a ?9 b& ( gre5i% lime/one 7#c7 conta9+ an admixture ( f9e volcanic detritus1 & p>tially cut out by an irregul> b$1 f\r to eight feet ?ick1 ( a highly slaggy1 gre5i%1 decompos+1 sph]oidal & amygdaloidal diabase 7#d74 ,?is unmi/akable lava-%eet is foll[$ by a b$ ( gre5 granul> tuff 7#e71 :i* 9 "s places rea*es a ?ickness ( ?ree feet1 b rapidly dies out4 ,ov] a space sev]al y>ds 9 bread?1 ! succe$+ /rata are conceal$1 & ! next visible rock is a d>k1 compact dol]ite :i* wea!rs sph]oidally 7#f74 7c7 ,tuffs )\t ,lavas4--,mr4 ,bemrose has %[n t "s ( ! b&s ( toad/one consi/ entirely ( b$d$ tuff4 ,9 ^! cases1 s f> z ! pres5t visible outcrops all[ u to judge1 no outfl[ ( lava accompani$ ! eruption ( fragm5t>y mat]ials4 ,b t ! ejection ( ^! mat]ials 0 n ! result ( a sudd5 spasmodic explosion1 b ( a cont9u$ s]ies ( dis*>ges v>y+ 9 duration & int5sity1 is indicat$ by ! well-b$d$ "* ( ! tuff & ! alt]nation ( f9] & co>s] lay]s4 ,l>ge blocks ( lava1 two feet or m 9 diamet]1 may m>k "s ( ! m vigor\s p>oxysms ( ! v5ts1 :ile ! usual f9e granul> nature ( ! tuff may po9t to ! prevail+ uni=mity & less viol5t "* ( ! eruptions4 ,b&s ( tuff #gj feet or m 9 ?ickness1 )\t ! int]calation ( any lime/one or o!r non-volcanic int]calation1 po9t to episodes ( su* cont9u$ volcanic activity t ! ord9>y s$im5tation ( ! sea-bottom 0 int]rupt$1 or at lea/ mask$1 by ! abundant fall ( du/ & /ones4 ,"o ( ! be/ exposures ( su* int]calations ( b$d$ tuffs 0 po9t$ out to me by ,mr4 ,bemrose1 imm$iately to ! ea/ ( ! village ( ,litton4 ,! matrix is cr[d$ ) ! usual m9utely vesicul> glassy lapilli1 & encloses fragm5ts ( diabase ( all sizes1 up to blocks m ?an a foot 9 diamet]4 ,! rock is well /ratifi$1 & ! lay]s ( co>se & f9e detritus pass b5ea? a gr\p ( lime/one b$s4 ,! actual junction is conceal$ "u ! roadway1 b only two or ?ree feet ( rock _c be se54 ,! l[e/ visible lay] ( lime/one is nodul> & conta9s decay$ blui% fragm5ts :i* may be volcanic lapilli4 ,imm$iately above ! l[] lime/ones ! calc>e\s b&s become ri*ly fossilif]\s4 ,"s ( _! lay]s consi/ ma9ly ( l>ge bun*es ( coral2 o!rs are cr[d$ ) cup-corals1 or are made up ma9ly ( cr9oids ) abundant bra*iopods1 polyzoa1 lamellibran*s1 ga/]opods & occasional fi%-tee?4 ,?is rem>kable pr(usion ( m>9e life is int]e/+ inasmu* z x succe$s imm$iately ! b& ( volcanic a%4 ,ano!r well-m>k$ zone ( tuff1 ) no traceable accompanim5t ( lava1 has already be5 ref]r$ to z connect$ ) ! ,grangemill v5ts4 ,9 ?is case also1 ! lime/one t lies directly ^u ! volcanic mat]ial is r impure & nodul> 9 "*4 ,! tuff itself is well b$d$1 p]haps f #gj to #ajj feet ?ick & dips und]nea? an ov]ly+ s]ies ( m>9e lime/ones4 ,i did n obs]ve ?9 p>t+s ( tuff & dissem9at$ volcanic lapilli among ! lime/ones1 su* z are s m>k$ 9 ! ,l[] ,c>bonif]\s =mations ( ,we/ ,lo?ian1 & 9 ! ,lim]ick bas91 to be describ$ 9 ! foll[+ *apt]4 ,b a dilig5t se>* might discov] examples ( !m1 & ?us prove t1 besides ! m prolong$ & cont9u\s eruptions t produc$ ! ?ick b&s ( tuff1 !re 7 occasional feeble & int]mitt5t explosions dur+ ! accumulation ( ! ?ick %eets ( lime/one4 ,"s ( ! lay]s ( r$ clay obs]v$ 9 %afts sunk = m9+ purposes may p]haps repres5t su* spasmodic dis*>ges ( f9e fragm5tal mat]ial4 #e4 ,,! ,,sills4--,no attempt has yet be5 made to det]m9e :e!r & to :at ext5t ! toad/one b&s include true intrusive %eets4 ,my own brief exam9ation ( ! gr\nd does n w>rant me 9 mak+ any positive /atem5t on ?is subject4 ,i c h>dly d\bt1 h[ev]1 t "s1 p]haps n a few1 ( ! toad/one b&s are really sills4 ,9 ! acc\nts ( ^! rocks conta9$ 9 ! m9+ records a di/9ction1 z already rem>k$1 appe>s to h be5 g5]ally drawn betwe5 toad/one & black/one4 ,! latt] t]m is appli$ to ! black1 fre%1 m co>sely cry/all9e1 & g5]ally non-amygdaloidal rocks1 :i*1 s f> z ,i h be5 able to exam9e !m1 h ! g5]al ext]nal & _m ( ! int]nal *>act]s ( ! ,c>bonif]\s sills ( ,c5tral ,scotl&4 ,at ,snitt]ton ne> ,matlock "o ( ^! black/ones1 z already m5tion$1 is said to h be5 f\nd to be #bdj feet ?ick4#de ,footnote #de3 ,nor? ,d]by%ire ,memoir1 p4 #bc4 ,x is /at$ t ! toad/ones1 ?\gh subject to great v>iations 9 ?ickness1 are nev] se5 to cut across ! lime/ones4#df ,b ,i suspect t pro(s ( intrusion & transgression w be f\nd :5 dilig5tly s\ght =4 ,x appe>$ to me t ! d>k1 compact1 cry/all9e dol]ite1 :i* 0 =m]ly qu>ri$ 9 ! middle ( ,tideswell ,dale1 may be sep>at$ f ! vesicul> toad/one ( t valley1 :i* is und\bt$ly a true lava-fl[1 & t x does n always occupy ! same horizon !re1 be+ sometimes bel[ & sometimes above ! amygdaloid4 ,:]e x re/s on a b& ( r$ clay ! latt] rock has be5 made column> to a dep? ( n9e feet4#dg ,alt]ation ( ?is k9d is v r>e among ! ,c>bonif]\s b$d$ lavas1 b is by no means infrequ5t 9 ! case ( sills4 ,b ! mo/ important pro( ( alt]ation :i* ,i h myself obs]v$ occurs at ,dale ,f>m ne> ! village ( ,peak ,=e/1 :]e ! lime/one above a co>sely cry/all9e dol]ite has be5 conv]t$ into a :ite sac*>oid m>ble = ab\t two y>ds f ! junction4 ,footnote #df3 ,op4 cit4 p4 #abc4 ,footnote #dg3 ,j4 ,m4 ,mello1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xxvi4 7#ahga71 p4 #gja4 #c4 ,,! ,,isle ,,( ,,man ,ris+ f ! middle ( ! ,iri% ,sea1 )9 sight ( ea* ( ! ?ree k+doms1 ) a hi/ory & associations s di/9ct1 yet s intimately l9k$ ) ^? ( ! re/ ( ,brita91 ?is int]e/+ isl& pres5ts 9 its geological /ructure features t connect x alike ) ,engl&1 ,scotl& & ,irel&1 :ile at ! same "t x reta9s a m>k$ individuality 9 reg>d to "s ( ! rocks t =m its framework4 ,its great c5tral ridge ( grits & slates1 :i* /ill rises #bjjj feet above ! sea 9 ! summit ( ,snaefell1 mu/ h =m$ a tract ( dry l& 9 ,c>bonif]\s "t1 until x sank "u sea-level1 & 0 buri$ b5ea? ! ,c>bonif]\s & lat] =mations4 ,along ! s\!rn m>g9 ( ?is anci5t l&1 a relic ( ! floor ( ! ,c>bonif]\s sea has be5 pres]v$ 9 a small bas9 ( ,c>bonif]\s ,lime/one :i* cov]s ab\t sev5 or eight squ>e miles4 ,?is remnant has a special int]e/ 9 geological hi/ory1 = x has pres]v$ ! records ( a s]ies ( volcanic eruptions :i* took place contemporane\sly ) ! deposition ( ! ,c>bonif]\s ,lime/one4 ,! geology ( ! ,isle ( ,man 0 sket*$ 9 outl9e by ,j4 ,f4 ,b]g]1#dh ,j4 ,maccullo*1#di & ,j4 ,s4 ,h5sl[1#ej & 0 aft]w>ds m fully illu/rat$ by ,j4 ,g4 ,cumm+4#ea ,to ! la/-nam$ obs]v] we owe ! recognition ( true int]calat$ volcanic rocks among ! calc>e\s =mations ( ! s\!rn end ( ! isl&4 ,^! rocks h subsequ5tly be5 /udi$ 9 great] detail by a numb] ( geologi/s4 ,an excell5t g5]al acc\nt ( !m 0 publi%$ 9 #ahgd by ,mr4 ,john ,horne1 ( ! ,geological ,survey4#eb ,a few ye>s lat] "s fur!r obs]vations on !m 7 prep>$ by ,j4 ,clifton ,w>d4#ec ,m rec5tly _! petrography has be5 /udi$ by ,messrs4 ,e4 ,dickson1 ,p4 ,holl& & ,f4 ,rutley1#ed & 9 m detail by ,mr4 ,b4 ,hobson4#ee ,to "s ( ! obs]vations ( ^! writ]s ref]5ce w be made 9 ! succe$+ pages4 ,dur+ ! progress ( ! ,geological ,survey 9 ! ,isle ( ,man1 ! rocks 9 "q h be5 mapp$ 9 detail by ,mr4 ,a4 ,/rahan & ,mr4 ,g4 ,w4 ,lamplugh1 & ,i h _h an opportunity ( exam9+ ! coa/-sections ) ! la/-nam$ geologi/4 ,! foll[+ description ( ^! sections is tak5 ma9ly f my field note-book4 ,! full details w appe> 9 ! (ficial ,memoirs4 ,footnote #dh3 ,trans4 ,geol4 ,soc4 #a/ s]4 vol4 ii4 7#ahad71 p4 #bi4 ,footnote #di3 ,we/]n ,isl&s ( ,scotl& 7#ahai71 vol4 ii4 p4 #ega4 ,footnote #ej3 ,trans4 ,geol4 ,soc4 #a/ s]4 vol4 v4 7#ahba71 p4 #dhb4 ,footnote #ea3 ,! ,isle ( ,man 7#ahdh71 *ap4 x4 ,footnote #eb3 ,trans4 ,geol4 ,soc4 ,ed94 ii4 7#ahgd71 p4 #ccb4 ,footnote #ec3 ,geol4 ,mag4 #ahhj1 p4 #d4 ,footnote #ed3 ,proc4 ,liv]pool ,geol4 ,soc4 vol4 vi4 7#ahhh-hi71 p4 #abc4 ,footnote #ee3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xlvii4 7#ahia71 p4 #dcb4 ,?is pap] 0 repr9t$ ) additions & corrections 9 ,yn ,lio> ,mann9agh1 ,d\glas1 ,isle ( ,man1 vol4 i4 ,no4 #aj1 ,april #ahib4 ,x may be rem>k$ at ! outset t ! la/ outcrop ( ! plateau-lavas ( ! ,solway bas9 occurs only #fj miles f ! s\? end ( ! ,isle ( ,man1 at ! foot ( ! hills ( ,gall[ay1 ! blue outl9e ( :i* c be se5 f t isl&4 ,! di/ance f ! ,manx volcanoes to ! ne>e/ ( ! puys ( ,liddesdale is ab\t #ajj miles4 ,?\gh ! fragm5t :i* has be5 left ( ! ejections is too small to w>rant any confid5t p>allelism1 !re appe>s to be reason to believe t1 alike 9 geological age & 9 mann] ( activity1 ! ,manx volcanoes may be class$ ) ! type ( ! puys4 ,! ,c>bonif]\s /rata ( ! ,isle ( ,man lie 9 a small tr\gh at ! s\? end ( ! isl&4 ,! l[e/ memb]s ( ! s]ies consi/ ( r$ conglom]ates & s&/ones1 :i* pass upw>d into d>k lime/ones full ( ! *>act]i/ic fossils ( ! ,c>bonif]\s ,lime/one4 ,z ! bottom ( ! bas9 is on ! :ole incl9$ seaw>ds1 ! highe/ /rata occur along ! extreme s\!rn coa/4 ,x is !re t ! volcanic rocks are display$4 ,!y occupy a n>r[ /rip less ?an two miles 9 l5g?1 :i* is almo/ entirely conf9$ to ! range ( cliffs & ! l$ges ( ! =e%ore4 ,yet ?\gh ?us extremely limit$ 9 area1 !y h be5 s admirably dissect$ along ! coa/1 t !y furni% a s+ul>ly ample body ( evid5ce be>+ on ! hi/ory ( ,c>bonif]\s volcanic action4 ,un=tunately ! bottom ( ! volcanic gr\p is n[h]e visible4 ,at ! ea/ or l[] end ( ! s]ies1 expos$ on ! %ore1 an agglom]ate ) its dykes appe>s to truncate ! ,ca/let[n ,lime/ones4 ,no trace ( any tuff has be5 notic$ among ^! l[] lime/ones4 ,we may inf] t ! volcanic activity began aft] !y 7 deposit$4 ,! highe/ accessible portions ( ! volcanic gr\p1 z ,mr4 ,horne %[$1 are cle>ly expos$ on ! coa/ at ,poyll ,vaai%1 int]calat$ 9 & ov]ly+ ! d>k lime/ones ( t locality 7,fig4 #ahd71 :i* h be5 assign$1 f _! fossil cont5ts1 to ! upp] "p ( ! ,c>bonif]\s ,lime/one s]ies4#ef ,! ,manx volcanoes may !re=e be reg>d$ z hav+ probably be5 9 eruption dur+ ! lat] portion ( ! ,c>bonif]\s ,lime/one p]iod4 ,footnote #ef3 ,r4 ,e!ridge jun41 9 ,mr4 ,horne's pap] above cit$4 ,illu/ration3 ,fig4 #ahd4--,lime/ones pass+ "u /ratifi$ tuffs1 ,poyll ,vaai%1 ,isle ( ,man4 ,ow+ to irregul>ities ( incl9ation1 ! ?ickness ( ! volcanic gr\p c only be approximately e/imat$4 ,x is probably n less ?an #bjj or #cjj feet4 ,b z m]ely ! edge ( ! gr\p lies on ! l&1 ! volcanic rocks may rea* a consid]ably great] ext5t & ?ickness "u ! sea4 ,! volcanic mat]ials consi/ ma9ly ( b$d$ tuffs1 b include also sev]al necks ( agglom]ate & a numb] ( dykes & sills4 ,s f> z ,i h obs]v$1 !y comprise no true lava-/reams4#eg ,^! ,manx tuffs pres5t _m ( ! famili> features ( ^? belong+ to ! puy-eruptions ( ,c5tral ,scotl&1 b ) "s peculi>ities wor?y ( att5tion4 ,!y are on ! :ole di/9ctly b$d$1 & z _! incl9ation is g5]ally 9 a we/]ly direction1 an asc5d+ ord] c be trac$ 9 !m f ! ea/]n end ( ! section to ! highe/ p>ts ( ! gr\p associat$ ) ! ,poyll ,vaai% lime/ones4 ,_! col\r is ! usual dull yell[i%-gre51 v>y+ slightly 9 t9t ) *anges 9 ! texture ( ! mat]ials1 ! pale/ b&s consi/+ ( ! f9e/ du/ or volcanic mud4 ,great diff]5ces 9 ! size ( _! fragm5t>y con/itu5ts may be obs]v$ 9 successive b$s1 co>se & f9e b&s rapidly alt]nat+1 ) no admixture ( non-volcanic s$im5t1 ?\gh occasional lay]s ( f9e a% or mud/one1 %[+ di/9ct curr5t-b$d+1 may be notic$4 ,footnote #eg3 ,! occurr5ce ( int]calat$ lavas has be5 describ$ 9 ?is s]ies1 b1 z ,i %all %[ 9 ! sequel1 !y are probably intrusive masses4 ,pauses 9 ! succession ( eruptions are m>k$ by ! int]calation ( seams ( lime/one or gr\ps ( lime/one1 %ale & black impure *]t4 ,su* int]/ratifications are sometimes curi\sly local & int]rupt$4 ,!y may be obs]v$ to die out rapidly1 !reby all[+ ! tuff above & bel[ !m to unite into "o cont9u\s mass4 ,!y seem to h be5 accumulat$ 9 holl[s ( ! tuff dur+ some:at prolong$ int]vals ( volcanic quiesc5ce1 & to h be5 sudd5ly br\ght to an end by a r5ewal ( ! eruptions4 ,!re are "s f\r or five su* int]calat$ gr\ps ( calc>e\s /rata 9 ! ?ick s]ies ( tuffs1 & we may reg>d !m z m>k+ ! *ief pauses 9 ! cont9uity or en]gy ( ! volcanic explosions4 ,an att5tive exam9ation ( ^! int]polat$ s$im5t>y deposits af=ds "s int]e/+ in=mation z to ! subm>9e conditions 9 :i* ! eruptions took place4 ,! int]calations1 sometimes #ab feet or m 9 ?ickness1 consi/ ma9ly ( d>k lime/ones1 enclos+ ! usual ,c>bonif]\s ,lime/one fossils2 black %ales1 sometimes %[+ v fragm5t>y & mu* mac]at$ rema9s ( f]ns & o!r l&-plants2 & black impure argillace\s *]t or fl9t1 arrang$ 9 b&s int]pos$ betwe5 ! o!r /rata1 & also 9 deta*$ lumps & /r+s4 ,! d>k flaggy lime/ones & black %ales may be p>allel$ li?ologically ) ^? ( ,ca/let[n & ,poyll ,vaai%4 ,inde$1 !re seems to be little d\bt t !y repres5t ! contemporane\s type ( m>9e s$im5t t 0 ga!r+ on ! sea-floor outside ! volcanic area1 & :i* dur+ int]vals ( quiesc5ce or feeble eruptivity spread m or less cont9u\sly into t area4 ,! ?ick mass ( tuff mu/ ?us h be5 /rictly contemporane\s ) a gr\p ( calc>e\s muddy & silice\s deposits :i* ga!r$ ov] ! bottom beyond ! limits ( ! %[]s ( a%es4 ,illu/ration3 ,fig4 #ahe4--,section ( tuff1 %[+ int]calations ( black impure *]t1 we/ ( ,clos5y*ollagh ,po9t1 ne> ,ca/let[n1 ,isle ( ,man4 ,"o ( ! mo/ s+ul> features ( ^! s$im5t>y int]calations is ! occurr5ce ( ! black *]ty mat]ial4 ,x may g5]ally be obs]v$ be/ develop$ at ! bottom & top ( ea* gr\p ( includ$ /rata4 ,look+ at ! lumps ( ?is sub/ance scatt]$ ?r\gh ! adjo9+ tuffs1 we might at fir/ take !m = eject$ fragm5ts1 & su* no d\bt may h be5 ! d]ivation ( "s ( !m4 ,b fur!r exam9ation w %[ t1 z a rule1 !y are ( a concretion>y nature1 & 7 =m$ 9 situ contemporane\sly ) or subsequ5t to ! deposition ( ! tuffs4 ,! accompany+ section 7,fig4 #ahe7 repres5ts ! mann] 9 :i* ! *]t is di/ribut$ ?r\gh two or ?ree squ>e y>ds ( tuff ov]ly+ "o ( ! calc>e\s gr\ps4 ,! mat]ial has be5 segregat$ n only into lumps1 b into ve9s & b&s1 :i*1 ?\gh on ! :ole p>allel ) ! g5]al /ratification-planes ( ! deposits1 sometimes run irregul>ly 9 tongues or /r+s across ^! planes1 z %[n 9 ,fig4 #ahf1 :]e ! d>k *]t b& :i* ov]lies ! lime/ones & %ales s5ds a tongue upw>ds = sev]al in*es into ! ov]ly+ tuff4 ,t ^! int]/ratifi$ calc>e\s & muddy /rata 7 laid d[n 9 wat] ( "s consid]able dep? may be inf]r$ f _! g5]al li?ological *>act]s4 ,! d>k c>bonace\s aspect ( ! lime/ones po9ts to ! probable int]m+l+ ( mu* decay$ vegetation ) ! rema9s ( ! calc>e\s organisms ( :i* ^! /rata *iefly consi/4 ,! ?9 unimportant b&s or p>t+s ( d>k %ale %[ t only ! f9e/ muddy s$im5t rea*$ ! quiet dep?s 9 :i* ! /rata 7 deposit$1 :ile ! mac]at$ f]n-fragm5ts sugge/ a long flotation & ultimate entombm5t ( t]re/rial vegetation borne seaw>ds f "s neighb\r+ l&4 ,illu/ration3 ,fig4 #ahf4--,section ( int]calat$ d>k lime/one1 %ale & *]t 9 ! tuff s\? ( ,poyll ,vaai% ,bay1 ,isle ( ,man4 #a4 ,lime/ones & %ales2 #b4 ,*]t2 #c4 ,tuff4 ,! *]ty b&s & nodules1 l ! fl9ts ( ! *alk1 be> _! te/imony to ! quiet "* ( ! s$im5tation 9 r deep wat] beyond ! limits )9 :i* ! s$im5t f ! l& 0 ma9ly accumulat$ on ! sea-bottom4 ,! orig9 ( ^! silice\s p>ts ( ! s]ies ( deposits has /ill to be inve/igat$4 ,:e!r or n !y are to be ref]r$ to organic causes l *alk-fl9ts1 & ! radiol>ian *]ts ( ! ,l[] ,silurian sy/em1 !y furni% a fre% example ( ! rem>kable association ( su* silice\s mat]ial ) volcanic ph5om5a1 :i* has n[ be5 obs]v$ 9 _m widely sep>at$ areas all ov] ! _w4 ,if we next turn to ! /ratification ( ! tuffs1 we obta9 fur!r evid5ce ( undi/urb$ conditions ( deposition on ! sea-floor4 ,! b$d+ ( ^! volcanic masses1 ?\gh di/9ct1 appe>s = ! mo/ "p to be due r to ! eruption & settlem5t ( alt]nately f9] & co>s] detritus ?an to any m>k$ drift+ & re>rangem5t ( ^! mat]ials by curr5t-action into diff]5t lay]s4 ,?r\gh\t ! s]ies ( tuffs1 inde$1 !re is1 on ! :ole1 a notable abs5ce ( any /ructure sugge/ive ( /rong curr5ts or ( wave-action 9 ! disp]sal & reassortm5t ( ! volcanic detritus4 ,! a%es & /ones 7 dis*>g$ 9 su* a way z to ga!r irregul>ly ov] ! sea-floor into ridges & holl[s4 ,!re does n seem to h be5 suffici5t movem5t 9 ! bottom wat] to level d[n ^! inequalities ( surface1 = we f9d t !y rema9$ long en\gh to all[ twelve feet or m ( calc>e\s & silice\s ooze to ga!r 9 ! holl[s1 :ile ! int]v5+ ridges /ill /ood uneffac$ until buri$ "u ! next fall ( a%es4 ,at r>e int]vals "s transi5t curr5t or deep] wave may h rea*$ ! bottom & spread out ! volcanic detritus ly+ !re4 ,su* exceptional di/urbances ( ! /ill wat] are n improbably indicat$ by occasional well-def9$ /ratification1 & ev5 by di/9ct false-b$d+1 9 c]ta9 f9] lay]s ( tuff4 ,! mat]ials ( ! tuffs are rem>kably uni=m 9 "* & conspicu\sly volcanic 9 orig94 ,) ! exception ( occasional blocks ( lime/one1 :i* range up to masses sev]al feet1 & occasionally sev]al y>ds1 9 diamet]1 ! du/1 lapilli & includ$ /ones consi/ entirely ( fragm5t>y basic lava1 s p]si/5t 9 its li?ological features t we may reg>d its slightly diff]5t v>ieties z m]ely m>k+ diff]5t conditions ( ! same rock4 ,! accumulation ( pumice\s a% 9 ?is s\!rn coa/ ( ! ,isle ( ,man is "o ( ! mo/ rem>kable 9 ,brita94 ,z ,mr4 ,hobson has well %[n1 ! matrix ( ?is tuff consi/s ( irregul> lapilli1 repres5t+ :at may h be5 v>i\s conditions ( solidification 9 "o orig9al volcanic magma4 ,?is magma he has describ$ z an augite-porphyrite or oliv9e-basalt4 ,"s ( ! lapilli1 z he not$1 consi/ ( a pumice cr[d$ ) vesicles :i* occupy m space ?an ! solid "p2 o!rs %[ ne>ly z _m vesicles1 b ! glass is made br[n by ! numb] ( its f9e du/-l inclusions2 a ?ird type pres5ts ! cells & cell-walls 9 ne>ly equal proportions4 ,! same obs]v] f\nd t :]e ! sub/ance is mo/ cellul> ! vesicles1 fairly uni=m 9 size1 measure ab\t a t5? ( a millimetre 9 longe/ diamet]4 ,an int]e/+ feature ( ! tuffs is ! abundant occurr5ce ( loose felsp> cry/als ?r\gh\t ! :ole gr\p up to ! highe/ visible /rata4 ,^! cry/als1 sometimes ne>ly an in* 9 l5g?1 appe> conspicu\sly z :ite spots on wea!r$ surfaces ( ! rock4 ,!y are s mu* decay$1 h[ev]1 t x is difficult to extract !m entire4 ,on ! mo/ cursory inspection !y are obs]v$ to enclose blebs ( a gre5i% sub/ance l ! mat]ial t fills up ! vesicles 9 ! pumice\s fragm5ts & 9 ! pieces ( cellul> lava4 ,i h n asc]ta9$ ! orig9al s\rce ( ^! scatt]$ felsp>s4 ,9 "o ( ! dykes on ! nor? side ( ! agglom]ate at ,sc>let ,po9t1 z 0 po9t$ out by ,mr4 ,hobson1 l>ge cry/als ( plagioclase occur 9 ! melaphyre1 b ! felsp>s 9 ! tuffs & agglom]ates diff] s mu* f ^! t we _c suppose !m to h come f ! explosion ( su* a rock4 ,i fail$ to detect any o!r m9]al 9 deta*$ cry/als 9 ! tuffs1 b a m dilig5t se>* might reveal su*1 & af=d "s gr\nds = speculat+ on ! probable nature ( ! magma f ! explosion ( :i* ! scatt]$ cry/als 7 d]iv$4 ,x is at lea/ c]ta9 t ?is magma mu/ h includ$ a l>ge proportion ( plagioclase cry/als4 ,betwe5 ! lapilli & ! m9ute pumice-du/ t con/itute ! matrix ( ?is tuff mu* calcite may be detect$4 ,?\gh ?is m9]al may h be5 p>tly d]iv$ f ! decay ( ! felsp> 9 ! lava-fragm5ts1 ,i believe t x is ma9ly to be attribut$ to ! int]m+l+ ( f9e calc>e\s ooze ) ! a% accumulat$ on ! sea-floor4 ,a m rem>kable association ( ! same k9d w be describ$ 9 lat] pages f ,k+'s ,c\nty 9 ,irel&4 ,t abundant calc>e\s organisms peopl$ ! sea 9 :i* ! ,manx ,c>bonif]\s volcanoes 7 active is %[n by ! contemporane\sly deposit$ lime/ones4 ,! tuffs !mselves are occasionally fossilif]\s4 ,species ( ,spirif]1 ,productus & o!r bra*iopods1 toge!r ) brok5 /ems ( encr9ites1 may be f\nd 9 !m1 & d\btless ! diffus$ calcite1 ?\gh n[ cry/all9e1 z 9 ! lime/ones1 & %[+ no organic /ructure1 owes its pres5ce to ! detritus ( once liv+ organisms4 ,! /ones imb$d$ 9 ! tuff consi/ almo/ exclusively ( slightly diff]5t v>ieties ( ! same pale1 always vesicul> rock1 & sometimes pass into a co>se slag4 ,!y v>y up to six feet or m 9 l5g?4 ,9 _m cases1 !y appe> to h be5 d]iv$ f ! disruption ( already solidifi$ lava1 = _! vesicles are n elongat$ or arrang$ ) ref]5ce to ! =m ( ! block1 b h be5 brok5 across & appe> 9 section on ! out] surface4 ,9 o!r in/ances1 h[ev]1 ! cavities are l>ge & irregul> 9 ! c5tre ( ! block1 :ile on ! outside !y are small] & are drawn out r\nd ! rudely sph]ical %ape ( ! mass1 z 9 true volcanic bombs4 ,! lime/one fragm5ts enclos$ 9 ! tuff include pieces ( ! d>k c>bonace\s & ( ! pale encr9al v>ieties4 ,9 no case did ,i obs]ve any s5sible alt]ation ( ^! fragm5ts4 ,!y seem to h be5 d]iv$ f mat]ial disrupt$ & eject$ dur+ ! op5+ ( successive v5ts1 & n to h be5 expos$ = any consid]able "t to ! metamorphic influ5ce ( volcanic heat & vap\rs4 ,n>r[ ?\gh ! /rip ( volcanic mat]ial is along ! s\? coa/ ( ! ,isle ( ,man1 x has =tunately pres]v$ = u "s ( ! v5ts f :i* ! tuffs 7 eject$4 ,a gr\p ( ^! v5ts1 ?ree or f\r 9 numb]1 may be trac$ along ! %ore 9 a g5]al ,w4,n4,w4 & ,e4,s4,e4 l9e f ,sc>let ,po9t = r m ?an a mile4 ,_! m>g9s are 9 "s places exce$+ly well def9$4 ,! mo/ /rik+ example ( ?is feature occurs 9 ! mo/ we/]ly v5t1 :]e a neck ( rem>kably co>se volcanic agglom]ate rises v]tically ?r\gh well-b$d$1 we/]ly-dipp+ tuff 7,fig4 #ahg74 ,9 o!r portions ( _! b\nd>ies no %>p l9e c be drawn betwe5 ! mat]ial fill+ ! v5t & t ( ! surr\nd+ tuffs4 ,h5ce x is difficult to def9e precisely ! =m & size ( ! v5ts4 ,i am incl9$ to believe f ?is indef9it5ess ( outl9e1 & f ! rem>kable /ructure ( ! dykes1 to :i* ,i %all aft]w>ds ref]1 t ! pres5tly visible p>ts ( ^! necks mu/ lie close to ! m\?s ( ! orig9al v5ts1 if inde$ !y d n actually conta9 p>ts ( ! crat]s & ( _! surr\nd+ walls4 ,! mat]ials t h fill$ up ! eruptive v5ts consi/ *iefly ( agglom]ate1 b p>tly also ( intrusive portions ( vesicul> lava4 ,! agglom]ate is compos$ ( simil> mat]ials to ! tuffs4 ,its matrix %[s ! same extraord9>ily abundant f9e gre5i%-grey basic pumice\s lapilli1 ) ! same k9d ( pl5tiful loose felsp>-cry/als4 ,! l>ge blocks ( lava1 too1 resemble 9 composition & /ructure ^? ( ! b$d$ tuffs1 b greatly exce$ !m 9 size & abundance4 ,besides ! fragm5ts ( vesicul> lava1 !re occur also occasional blocks ( lime/one4 ,"s ( ^! are sev]al y>ds 9 l5g?4 ,messrs4 ,/rahan & ,lamplugh h mapp$ a l>ge mass ( lime/one at ! ,sc>let v5t1 :i*1 s f> z c be obs]v$1 lies 9 ! agglom]ate--a l>ge cake ( :ite lime/one ) pebbles ( qu>tz1 :i* has probably be5 brok5 (f f "s und]ly+ b$ & c>ri$ up 9 ! *imney ( ! volcano4 ,z a rule ! agglom]ate is a tumultu\s1 un/ratifi$ mass4 ,b 9 _m places x %[s l9es ( b$d+ &1 z already /at$1 passes outw>d into ord9>y b$d$ tuff1 ! numb] & size ( ! eject$ blocks rapidly dim9i%+4 ,:]e ?is transition occurs we seem to see a remnant ( ! base ( ! actual volcanic cone4 ,?us1 9 ! mo/ we/]ly v5t already cit$1 :ile ! wall ( ! v5t has be5 laid b>e on ! side next ! sea1 s t ! agglom]ate on ! bea* desc5ds v]tically ?r\gh ! surr\nd+ b$d$ tuffs1 on ! we/]n side ! cliffs h pres]v$ a portion ( ! mat]ial t accumulat$ outside ! orifice 7,fig4 #ahg74 ,9 ?is section we obs]ve t ! co>se agglom]ate :i* fills up ! ma9 "p ( ! v5t has be5 left ) a hummocky1 unev5 surface1 & t a subsequ5t & p]haps feebl] eruption ( f9] mat]ial has cov]$ ov] ^! inequalities1 & has ext5d$ to ! left above ! f9e tuffs ?r\gh :i* ! agglom]ate has be5 drill$4 ,illu/ration3 ,fig4 #ahg4--,section ( "p ( a volcanic neck on %ore to ! s\?-ea/ ( ,poyll ,vaai% ,bay1 ,isle ( ,man4 ,illu/ration3 ,fig4 #ahh4--,section ( successive dis*>ges & di/urbances )9 a volcanic v5t4 ,sc>let ,po9t1 ,isle ( ,man4 ,aga91 9 ! l>ge/ ( ! v5ts1 t ne> ,sc>let ,po9t1 /ill cle>] pro( ( successive eruptions & dislocations )9 a volcanic *imney may be notic$4 ,at "o po9t ! accompany+ section 7,fig4 #ahh7 has be5 laid b>e by ! waves4 ,! olde/ accumulation is a f9e gre5 granul> tuff 7a71 rudely & fa9tly arrang$ 9 lay]s incl9$ at high angles1 l ! f9e mat]ials 9 _m ( ! v5ts ( ! bas9 ( ! ,fir? ( ,=?4 ,?is peculi> /ratification1 due n to ! assortm5t ( mat]ials 9 wat]1 b to ! deposition ( co>s] & f9] detritus by successive explosions1 & to subsequ5t slipp+ or tilt+1 is a *>act]i/ic feature ( ! detritus :i* has fill$ up anci5t volcanic funnels4 ,a lat] explosion f "s adjac5t "p ( ! same v5t has giv5 rise to ! dis*>ge ( a co>se agglom]ate 7b71 :i* ) blocks sometimes six feet long1 ov]spreads ! e>li] mat]ial4 ,a ?ird detrital accumulation 9 ! same v5t1 consi/+ ( a firm brecciat$ tuff 7c7 ) mu* calcite 9 its matrix1 has be5 br\ght d[n by a slip 7f7 :i* cuts across bo? ( ! previ\s deposits4 ,a broad dyke 7d7 ( vesicul> diabase 7augite-porphyry7 trav]ses ! v5t1 & is probably lat] ?an any ( ! o!r rocks 9 ! section4 ,i w conclude ?is acc\nt ( ! ,manx ,c>bonif]\s volcanic rocks ) a brief ref]5ce to ! intrusive masses :i* =m a prom95t feature ( ! coa/-l9e4 ,f ! picturesque headl& ( ,sc>let ,po9t ! broad dyke :i* =ms t promontory may be trac$ = "s di/ance we/w>ds4 ,sev]al o!r p>allel dykes run 9 ! same direction :i*1 x w be obs]v$1 is also t ( ! *a9 ( v5ts4 ,x might be said t ! v5ts are1 z x 71 /rung toge!r by a l9e ( dykes4 ,^! eruptive masses trav]se bo? ! agglom]ates & ! b$d$ tuffs4 ,!y probably belong1 !re=e1 to a comp>atively late "p ( ! volcanic hi/ory4 ,t !y are truly intrusive & n lava-fl[s is1 ,i ?9k1 cle>ly %[n by _! v]tical walls :i* desc5d ?r\gh ! surr\nd+ rocks1 & by ! great] clos5ess ( _! texture1 z well z ! dim9ution 9 ! size ( _! vesicles along ! contact surfaces4 ,b x mu/ be admitt$ t 9 _! rem>kably develop$ vesicul> /ructure !y look m l /reams ( lava ?an ord9>y dykes4 ,x is ?is /ructure :i* gives to ^! dykes _! peculi> int]e/4 ,b&s ( vesicles1 f an in* or less to sev]al in*es 9 bread?1 run along ! dykes p>allel to ! out] walls4 ,unlike ! famili> r[s ( little amygdaloidal cells 9 ord9>y basalt dykes1 su* z ^? ( ! ,t]ti>y s]ies 9 ,scotl&1 ^! vesicles1 ?\gh small & pea-l 9 ! n>r[] b&s t[>ds ! m>g9s ( ! dykes1 became s l>ge1 num]\s1 & irregul> 9 ! broad] & m c5tral b&s1 t ! rock passes !re into a r\gh slag4 ,illu/ration3 ,fig4 #ahi4--,section ( dyke & sill 9 ! tuffs we/ ( ,sc>let ,po9t1 ,isle ( ,man4 ,:ile ! intrusive mat]ial has = ! mo/ "p ris5 9 ! =m ( dykes1 9 "o "p ( ! coa/-section1 a little to ! we/ ( ,sc>let ,po9t1 x has be5 inject$ z a sill among ! b$d$ tuffs4#eh ,a section tak5 at ?is locality gives ! /ructure repres5t$ 9 ,fig4 #ahi4 ,on ! nor? side ( ! great dyke1 ! /rata ( tuff :i* dip "u x1 roll ov] & support an outly+ %eet ( ! same mat]ial4 ,! slaggy /ructure ( p>ts ( ?is sill give x "s resemblance to a true lava-fl[4 ,b x is ! same /ructure :i* c be se5 9 ! dykes1 :ile ! clos] gra9 along ! contact-surface fur!r connects x ) ^! intrusions4 ,footnote #eh3 ,x is ?is %eet :i* has be5 describ$ z a lava-/ream4 ,illu/ration3 ,fig4 #aij4--,section on s\? side ( vesicul> sill we/ ( ,sc>let ,po9t4 ,illu/ration3 ,fig4 #aia4--;,b&s ( vesicles 9 ! same sill4 ,!re is1 h[ev]1 a peculi>ity ab\t ! developm5t ( ! vesicul> /ructure 9 ?is sill :i* ,i h n obs]v$ any:]e else4 ,if we exam9e ! s\!rn side ( ! crag ne> its ea/]n end we obs]ve t ! successive b&s ( vesicles are arrang$ 9 ! same direction z ! surface ( contact ) ! und]ly+ tuffs1 precisely z !y are rang$ 9 dykes p>allel to ! b\nd+ walls4 ,s f> ! /ructure is q normal4 ,b1 mov+ a few y>ds we/w>ds1 we f9d t ! b&s beg9 to curve1 &1 in/ead ( foll[+ ! contact surface1 /rike x fir/ obliquely & !n at "r angles1 until we h ! /ructure %[n 9 ,fig4 #aia4 ,! b&s "h v>y f less ?an an in* to m ?an a foot 9 bread?1 & :]e broade/ assume a slaggy texture4 ,i s\ght 9 va9 = any evid5ce ( subsequ5t di/urbance su* z might h truncat$ ^! p>allel r[s ( vesicles & pu%$ ! rock bodily ov] ! tuffs4 ,! p]fect p>allelism ( ! b&s ) ! surface ( ! tuff at ! ea/ end1 & ! abs5ce ( all trace ( a ?ru/-plane at ! base ( ! sill1 seem to %[ t1 ?\gh ! r[s ( vesicles 7 und\bt$ly at fir/ arrang$ p>allel to ! surfaces betwe5 :i* ! intrusion took place1 ! mass1 be=e completely consolidat+ & com+ to re/1 0 ruptur$1 & a portion ( x 0 driv5 onw>ds at "r angles to its previ\s l9e ( movem5t4 ,a consid]ation ( ! s+ul>ly slag-l /ructure ( ! inject$ masses 9 ! tuffs & agglom]ates leads to ! conclusion t ?\gh :at we n[ see ( ^! rocks did n actually fl[ out at ! sea-bottom 9 /reams ( lava1 x 0 intrud$ s close to ! surface t ! imprison$ vap\rs _h opportunity to exp&1 z 9 sup]ficial outfl[s4#ei ,?is inf]5ce is 9 accord ) t d]iv$ f an exam9ation ( ! necks1 :]e9 we f9d evid5ce ( ! probable survival ( p>ts ( ! actual crat]s & volcanic cones4 ,footnote #ei3 ,z illu/rative ( ! occurr5ce ( ! vesicul> /ructure 9 sup]ficial intrusions1 ,i may aga9 cite ! dyke :i* cuts ! a% ( ! out] crat]-wall ( ! ,puy de ,p>i\ 9 ,auv]gne4 ,! &esite ( ?is dyke is 9 places z vesicul> z ! lava-/ream ) :i* x 0 d\btless connect$1 b ! vesicles h be5 flatt5$ & drawn out p>allel to ! walls ( ! dyke4 ,9 ?is in/ance x is q c]ta9 t !re c\ld nev] h be5 any great dep? ( detrital mat]ial above ! fissure into :i* ! mat]ial ( ! dyke 0 inject$ 7see vol4 i4 p4 #ff74 ,z ! records ( ! e>lie/ eruptions dur+ ! ,c>bonif]\s ,lime/one p]iod 9 ! di/rict ( ! ,isle ( ,man are conceal$1 s also ^? ( ! la/ ( ! s]ies lie "u ! sea4 ,:]e ! highe/ visible tuffs ov]lie ! ,poyll ,vaai% lime/ones !y %[ no *ange 9 ! nature ( ! mat]ials eject$1 or 9 ! en]gy ( eruption4 ,!y lie s abruptly on ! d>k calc>e\s deposits z to %[ t a consid]able pause 9 volcanic activity 0 foll[$ by a viol5t explosion4 ,! same abundant grey-gre5 pumice1 ! same k9d ( loose cry/als ( felsp>1 ! same type ( lava-blocks & bombs z _h *>act]iz$ ! =ego+ eruptions rema9$ z m>k$ at ! end4 ,b ! fur!r volcanic records _c be p]us$1 & we are left to speculate :e!r ! coa/-sections reveal almo/ ! :ole *ronicle1 or if !y m]ely lay be=e u ! e>ly *apt]s ( a great volcanic hi/ory ( :i* ! ma9 records lie buri$ "u ! waves ( ! ,iri% ,sea4 #d4 ,,ea/ ,,som]set ,v>i\s limit$ outcrops ( igne\s rocks h long be5 kn[n to occur 9 ! ea/]n "p ( ,som]set4 ,! l>ge/ ( ^! lies 9 ! mid/ ( ! ,old ,r$ ,s&/one1 on ! cre/ ( ! axis ( ! ,m5dip ,hills1 betwe5 ,d[nhead & ,beacon ,hill4 ,small] pat*es occur 9 ! ,c>bonif]\s ,lime/one ne> ,wr+ton ,w>r51 on ! nor? side ( ,middle ,hope1 on ,worle ,hill & at ,uphill4 ,^! rocks h be5 mapp$ z intrusive1 ?\gh "s ( !m h be5 describ$ z conglom]atic or z volcanic breccias4 ,:ile "s ( ! masses are probably intrusive1 o!rs appe> to be truly contemporane\s ) ! deposition ( ! ,c>bonif]\s ,lime/one4 ,! highly vesicul> basalt ( ,middle ,hope looks mu* m l a sup]ficial lava ?an an intrusion4 ,mr4 ,avel9e gave a section %[+ ?ree alt]nations ( lime/one & igne\s rock at ,middle ,hope4 ,a rec5t exam9ation ( t coa/-l9e by ,mr4 ,a4 ,/rahan %[s t !re are und\bt$ tuffs int]/ratifi$ ) ! calc>e\s /rata4 ,!re is ?us pro( t "o or m small volcanic v5ts 7 9 eruption on ! floor ( ! ,c>bonif]\s ,lime/one sea 9 ! neighb\rhood ( ,we/on-sup]-,m>e4#fj ,footnote #fj3 ,see ,geological ,survey ,memoir ,on ,ea/ ,som]set1 by ,h4 ,b4 ,woodw>d1 #ahgf1 & au?orities !re cit$4 ,mr4 ,avel9e's section above ref]r$ to w be f\nd on p4 #bb4 #e4 ,,devon%ire ,! *ange f ! typical ,old ,r$ ,s&/one ( ,s\? ,wales to ! ,devonian sy/em ( ,devon%ire1 to :i* ,i h already ref]r$1 is h>dly m /rik+ ?an ! contra/ betwe5 ! ,c>bonif]\s =mations ( ^! two areas4#fa ,! well-m>k$ ?reefold subdivisions ( ,c>bonif]\s ,lime/one1 ,mill/one ,grit & ,coal-measures1 s p]si/5t ?r\gh\t ,brita91 & n[h]e m typically develop$ ?an 9 ,s\? ,wales1 are replac$ 9 a di/ance ( less ?an =ty miles by ! peculi> ,culm-measures ( ,devon%ire--a s]ies ( black %ales1 grey s&/ones & ?9 lime/ones & l5ticul> seams ( impure coal 7culm71 :i* are n only s+ul>ly unlike 9 orig9al *>act]s to ! ord9>y ,c>bonif]\s =mations1 b h be5 made /ill m unlike by ! ext5sive & sev]e cleavage to :i* ! ,palozoic rocks ( ,devon & ,cornwall h be5 subject$4 ,t ^! ,culm-measures are truly ,c>bonif]\s is made abundantly cle> by _! fossil cont5ts1 ?\gh x has n yet be5 possible to det]m9e h[ f> !y include repres5tatives ( ! great /ratigraphical subdivisions 9 o!r p>ts ( ! c\ntry4 ,footnote #fa3 ,9 ! c5tre ( ,engl& num]\s outly+ areas ( igne\s rocks are f\nd 9 ! ,c>bonif]\s ,lime/one1 ,mill/one ,grit & ,coal-measures4 ,^! w be consid]$ by !mselves 9 ,*ap4 xxxii4 ,x is to ,de la ,be*e t geology owes ! fir/ intimation ( ! occurr5ce ( int]/ratifi$ igne\s rocks 9 ! ,c>bonif]\s s]ies ( ,devon%ire4 ,z f> back z ! ye> #ahcd1 9 8 s+ul>ly sugge/ive treatise1 ,rese>*es 9 ,!oretical ,geology1 ?is em95t geologi/ express$ 8 op9ion t n only 7 ! trappean b&s regul>ly int]calat$ 9 ! s$im5t>y s]ies & cont9u\sly traceable ) ! g5]al /ratification1 b t !y occurr$ at v>i\s localities 9 su* a mann] z to raise ! suspicion t ^! po9ts may m>k "s ( ! c5tres ( eruption4 ,he p>ticul>ly cit$ ! example ( ,br5t ,tor z a rem>kable volcanic-look+ hill1 compos$ 9 "p ( a conglom]ate hav+ e appe>ance ( volcanic c9d]s4#fb ,footnote #fb3 ,op4 ,cit4 p4 #chd4 ,9 8 subsequ5tly publi%$ ,report on ! ,geology ( ,cornwall1 ,devon%ire & ,we/ ,som]set1 ,de la ,be*e dwelt 9 m detail on ! results ( 8 /udy ( ^! rocks1 :i* he _h trac$ out on ! gr\nd & express$ ^u ! maps ( ! ,ordnance ,geological ,survey4#fc ,h>dly any additions h s9ce be5 made to our k ( ! field-relations ( ! rocks4 ,x is to ! maps & ,report ( ,de la ,be*e t we mu/ turn = ne>ly all ! publi%$ in=mation on ! subject4 ,i %all !re=e give "h a summ>y ( :at c be ga!r$ f ^! publications4 ,footnote #fc3 ,%eets #bb1 #bc1 #bd1 #be1 #cj1 #ca1 #cb & #cc4 ,9 trac+ ! limits ( ! ,culm-measures1 ,de la ,be*e f\nd t no well-def9$ l9e c\ld be drawn betwe5 ^! /rata & ! grauwacke or ,devonian =mations und]nea?4 ,! ,c>bonif]\s s]ies lies 9 a great tr\gh1 ( :i* ! axis runs ne>ly ea/ & we/1 s t ! l[e/ memb]s ( ! s]ies rise along ! nor!rn & s\!rn m>g9s4 ,b ,de la ,be*e 0 /ruck ) "o rem>kable contra/ betwe5 ! two opposite sides ( ! tr\gh--a contra/ :i* m>ks ! ,devonian z well z ! ,c>bonif]\s =mations ( ?is region4 ,on ! s\? side an abundant & p]si/5t gr\p ( int]calat$ b&s ( igne\s1 or z he call$ !m1 trappean1 mat]ials c be foll[$ along ! :ole l9e ( b\nd>y1 :ile no su* gr\p occurs on ! nor? side4 ,he f\nd ^! b&s to be l5ticul>1 traceable sometimes = a numb] ( miles1 !n dy+ out & reappe>+ on ! same or o!r horizons4 ,he mapp$ !m ! :ole way f ,bosca/le on ! we/ to ne> ,exet] on ! ea/1 & f\nd t ?\gh ! individual %eets might be %ort1 ! trappean zone 0 cont9u\s z f> z ! s\!rn m>g9 ( ! ,c>bonif]\s s]ies c\ld be se51 except :]e x _h be5 brok5 ?r\gh by ! great granitic mass ( ,d>tmoor4 ,he asc]ta9$ t ! int]calat$ trappean rocks are n conf9$ to ! ,culm-measures1 b occur also 9 ! contigu\s portions ( ! grauwacke or ,devonian sy/em4 ,b fur!r1 he cle>ly recogniz$ t ! b&s ( igne\s mat]ial :i* he mapp$ includ$ bo? gre5/ones1 toge!r ) o!r v>ieties ( massive eruptive rocks1 & also volcanic a% or tuff1 ?\gh he did n attempt to sep>ate ^! out ^u ! maps1 b cont5t$ himself ) repres5t+ !m all "u ! same col\r4 ,he admitt$ t "s d\bt might be ent]ta9$ z to ! age ( ! gre5/ones1 = "s ( !m might be intrusive & !re=e lat] ?an ! s$im5t>y deposits betwe5 :i* !y lie4 ,b he cont5d$ t !re c\ld be no unc]ta9ty ) reg>d to ! trappean a% or tuff1 :i* be+ regul>ly int]/ratifi$ 9 ! ,c>bonif]\s s]ies1 mu/ be contemporane\s ) x4 ,he po9t$ out t _m ( ! gre5/ones1 z well z fragm5ts 9 ! conglom]ates or a%es1 7 highly vesicul> & mu/ orig9ally h be5 9 ! condition ( pumice4 ,z an illu/ration ( ! c5tres ( eruption f :i* ^! mat]ials 7 eject$1 ,de la ,be*e drew special att5tion once m to ! conspicu\s em95ce ( ,br5t ,tor & ! rocks 9 its neighb\rhood4 ,8 rem>ks on ?is subject are well wor?y ( be+ quot$--,! idea t 9 ! vic9ity ( ,br5t ,tor a volcano has be5 9 action1 produc+ effects simil> to ^? produc$ by active volcanoes1 =cibly pres5ts itself4 ,t ?is volcano project$ a%es1 :i*1 fall+ into adjac5t wat]1 became int]/ratifi$ ) ! mud1 silt & s& !re deposit+1 seems probable4 ,t gre5/ones & o!r solid trappean rocks con/itut$ ! lavas ( t p]iod & locality1 "h & !re int]m+l$ ) ! a%1 appe>s also a reasonable hypo!sis4 ,^u ! :ole !re seems z good evid5ce z c\ld be expect$ t to ! nor? & nor?-we/ ( ,tavi/ock1 a%1 c9d]s & liquid melt$ rocks 7 eject$ & became int]m+l$ ) mud1 silt & s& dur+ ?is anci5t geological epo*1 correspond+ ) ! ph5om5a exhibit$ 9 connection ) volcanoes ( ! pres5t day1 m p>ticul>ly :5 !y adjo9 or are situat$ 9 ! sea1 or o!r wat]s :]e eject$ a%es1 c9d]s & lava c be int]m+l$ ) ord9>y mud1 silt & s&4#fd ,footnote #fd3 ,op4 cit4 p4 #abb4 ,x rema9s = "s future obs]v] to fill up ! outl9es ?us sket*$ by ,de la ,be*e1 by trac+ ! respective areas ( lavas & tuffs1 di/+ui%+ ! v>i\s petrographical types1 sep>at+ ! intrusive f ! int]/ratifi$ %eets1 id5tify+ ! necks & bosses t may m>k c5tres ( eruption1 & express+ ^! v>i\s details ^u maps on a suffici5tly l>ge scale4 ,a s]i\s difficulty 9 ?is rese>* arises f ! effect ( ! pr(\nd alt]ation :i* has be5 produc$ on ! igne\s rocks by ! cleavage ( ! region4 ,_m ( ! gre5/ones h be5 s cleav$ z to become slaty or almo/ s*i/ose4 ,de la ,be*e recogniz$ ?is *ange & wrote ( ! s*i/ose trappean a%4 ,a result ( ?is metamorphism has be5 to imp>t to rocks orig9ally massive ! same fissile /ructure z ! adjac5t slates possess2 & 9 ?is condition x is (t5 h>dly possible to di/+ui% betwe5 gre5/one & f9e-gra9$ a%4 ,!re c inde$ be little d\bt t among ^! ,c>bonif]\s volcanic rocks1 z we h se5 to be ! case ) ^? ( ! ,devonian sy/em 9 ! same region1 _m lavas or sills h be5 mapp$ z tuffs4 ,! *ief additions to our k ( ! ,c>bonif]\s volcanic gr\p ( ,devon%ire s9ce ! "t ( ,de la ,be*e h be5 made by ,mr4 ,f4 ,rutley1 ,mr4 ,w4 ,a4 ,us%] & ,g5]al ,m',mahon4 ,mr4 ,rutley#fe has endeav\r$ to trace ! respective areas occupi$ by ! diff]5t v>ieties ( volcanic rocks 9 ! di/rict ar\nd ,br5t ,tor1 ne> ,tavi/ock1 & to %[ ! probable connection ( ! successive b&s ( lavas & tuffs ) a c5tral v5t ( dis*>ge situat$ at t hill4 ,he believes t ^! b&s occur on f\r diff]5t horizons 9 ! s$im5t>y s]ies4 ,he has /udi$ ! microscopic /ructure ( ! rocks1 :i* 9 8 view include amphibolites1 gabbros1 basalts1 pit*/ones & s*i/ose a%es1 or cla/ic rocks ( a d\btful nature4#ff ,footnote #fe3 ,! ,eruptive ,rocks ( ,br5t ,tor & its ,neighb\rhood1 ,mem4 ,geol4 ,surv4 #ahgh4 ,on ! ,s*i/ose ,volcanic ,rocks occurr+ on ! we/ ( ,d>tmoor1 ) "s ,notes on ! ,/ructure ( ! ,br5t ,tor ,volcano1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxxvi4 7#ahhj71 p4 #bhf4 ,footnote #ff3 ,! ,eruptive ,rocks ( ,br5t ,tor1 p4 #de4 ,mr4 ,us%] has re-mapp$ ! tract ( ,culm-measures on ! ea/ side ( ! ,d>tmoor granite1 besides visit+ "s ( ! o!r areas outside ( ! granite mass4 ,:ile confirm+ ! g5]al accuracy ( ,de la ,be*e's survey1 he has be5 able to improve ! mapp+ by ins]t+ m detail1 sep>at+ especially ! tuffs f ! gre5/ones4 ,! latt] h be5 f\nd by him to be mo/ly dol]ites1 "s ( :i*1 f _! p>allelism ! b&s ( tuff1 may be 9 8 op9ion contemporane\s lavas1 ?\gh ! majority ( !m are evid5tly intrusive4 ,! tuffs are regul>ly int]/ratifi$ among ! ,culm-measures1 _! mo/ important b& 9 ?is di/rict hav+ an av]age bread? ( ab\t #ajj y>ds1 & be+ traceable = at lea/ two miles1 possibly consid]ably fur!r4#fg ,9 go+ ov] ?is tract ) ,mr4 ,us%] ,i 0 l$ to reg>d _m ( ! %eets ( diabase 7dol]ite7 or gabbro z true sills & bosses4 ,mo/ ( !m occur z %ort l5ticul> or oval pat*es tol]ably num]\s1 b n traceable = m ?an a %ort di/ance1 ?\gh a connection may (t5 exi/ :i* _c be detect$ by ! scanty evid5ce on ! surface4 ,"o %eet :i* has be5 foll[$ by ,mr4 ,us%] f ,combe to beyond ,a%ton1 a di/ance ( ne>ly two miles1 pres5ts 9 ! c5tre a some:at co>sely cry/all9e texture :i* rapidly gives way to a mu* clos] gra91 & ! rock !n becomes highly vesicul>4 ,x is ov]la9 ) d>k ,culm-%ales & b&s ( f9e %aly tuff1 pass+ upw>d into a granul> tuff4 ,"s lay]s ( ?is tuff assume a f9ely foliat$ appe>ance by ! developm5t ( pale leek-gre5 folia1 :i* %[ slick5sid$ surfaces p>allel ) ! b$d+4 ,! rock !n pres5ts "o ( ! usual appe>ances ( s*al/e94 ,?is /ructure seems obvi\sly due to me*anical movem5t along ! planes ( /ratification4 ,footnote #fg3 ,! ,briti% ,culm-measures1 ,proc4 ,som]set ,ar*ol4 & ,nat4 ,84 ,soc4 xxxviii4 7#ahib71 p4 #afa4 ,b&s ( black *]t & *]ty %ale are int]polat$ among ! tuffs1 :i* also conta9 "h & !re nodul> lumps ( simil> black impure e>?y *]t--an int]e/+ association l t allud$ to z occurr+ 9 ! ,c>bonif]\s volcanic s]ies ( ! ,isle ( ,man1 & l ! occurr5ce ( ! radiol>ian *]ts ) ! ,l[] ,silurian volcanic s]ies already describ$4#fh ,footnote #fh3 ,*]ts conta9+ num]\s species ( radiol>ia h rec5tly be5 f\nd by ,dr4 ,h9de & ,mr4 ,h[>d ,fox to =m an important "p ( ! ,l[] ,culm-measures ( ,devon%ire1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 li4 7#ahie71 p4 #fji4 ,! volcanic belt 9 ! valley ( ! ,teign c be foll[$ = ab\t two miles4 ,x is und\bt$ly int]/ratifi$ among ! d>k ,culm-measures1 :i* are di/9ctly se5 dipp+ "u & ov]ly+ x4 ,g5]al ,m',mahon has rec5tly %[n :at may be done by c>eful & detail$ exam9ation ( ! gr\nd broadly sket*$ 9 by ,de la ,be*e4 ,he *ose = /udy a /rip ( gre5/one %[n on ! ,geological ,survey ,map to ext5d = ab\t ?ree & a half miles along ! nor?-we/ m>g9 ( ! ,d>tmoor granite4 ,he has f\nd t :at is repres5t$ "u "o wa% ( col\r on t map includes bo? tuffs & lavas4 ,! tuffs1 9 spite ( ! alt]ation :i* !y appe> to h und]gone f ! proximity ( ! great granite mass1 are f\nd by microscopic inve/igation to be made up ( f9e volcanic du/ conta9+ m9ute lapilli ( v>i\s lavas4 ,sometimes z _m z six or sev5 diff]5t k9ds ( lava may be repres5t$ 9 ! same microscopic slide4 ,^! include felsitic or rhyolitic & tra*ytic rocks toge!r ) fragm5ts ( d>k glassy lava full ( magnetite du/4 ,) ! tuffs are int]calat$ %eets ( felsite & tra*yte4 ,9 ! same di/rict co>se volcanic agglom]ate occur1 made up ( blocks ( diff]5t lavas & pieces ( diff]5t s$im5t>y rocks4#fi ,footnote #fi3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 l4 7#ahid71 p4 #cch4 ,^! obs]vations are ( special int]e/1 inasmu* z !y po9t to ! eruption ( a mu* m acid s]ies ( volcanic lavas & tuffs ?an _h previ\sly be5 kn[n to exi/ 9 ! ,culm-measures4 ,until ! gr\nd has be5 m accurately mapp$1 x is impossible to say :e!r ^! rocks are old] or y\ng] ?an ^? t lie ar\nd ,br5t ,tor1 a few miles to ! s\?-we/4 ,g5]al ,m',mahon has not$ ! pres5ce ( m basic eruptive rocks 9 ! same di/rict4 ,he specially cites ! occurr5ce ( mica-diorite1 ( basaltic lavas alt]$ into a s]p5t9\s mass1 & ( a dol]ite :i* may possibly m>k ! actual v5t ( ! old ,br5t ,tor volcano4 ,8 obs]vations on ! influ5ce ( ! ,d>tmoor granite 9 induc+ new m9]al re>rangem5ts 9 ! igne\s rocks ( ! ,culm-measure s]ies are full ( int]e/4 ,,*apt] ,,xxx ,,! ,,c>bonif]\s ,,volcanoes ,,( ,,irel& ,k+'s ,c\nty--,! ,lim]ick ,bas9--,! ,volcanic ,breccias ( ,d\btful ,age 9 ,c\nty ,cork4 ,al?\gh ! ,c>bonif]\s sy/em spreads ov] by f> ! l>g] "p ( ! surface ( ,irel&1 & is laid b>e 9 _m ?\s&s ( natural & artificial sections1 x displays und\bt$ly contemporane\s igne\s rocks1 s f> z at pres5t kn[n1 at only "o locality--! region ar\nd ,lim]ick4 ,a second di/rict1 h[ev]1 lies 9 ,k+'s ,c\nty1 :]e "s v5ts occur :i* may be ( ,c>bonif]\s age1 & ( :i* a description w be giv5 9 ! foll[+ pages4 ,t ! relics ( volcanic action %\ld be s few1 :ile ! exposures ( ! ,c>bonif]\s =mations are s num]\s & s completely disclose ! geological hi/ory ( ! :ole sy/em1 mu/ be reg>d$ z good evid5ce t :ile volcanoes ab\nd$ & cont9u$ long active 9 ,scotl& & 9 p>ts ( ! ,c5tre & ,s\?-we/ ( ,engl&1 !y h>dly appe>$ at all 9 ,irel&4 ,x is wor?y ( rem>k1 also1 t ! ,iri% eruptions belong to ! "t ( ! ,c>bonif]\s ,lime/one--a p]iod di/+ui%$ by volcanic activity 9 ,scotl& & ,engl&--t ! nature ( ! mat]ials erupt$ be>s a close resemblance to t ( ! lavas & tuffs ( ! si/] isl&1 & t ! mann] ( _! eruption f9ds a close c\nt]p>t 9 ! ,puy-eruptions1 already describ$4 #a4 ,,k+',s ,,c\nty ,9 ! progress ( ! ,geological ,survey sev]al small tracts ( gre5/one a% & gre5/one 7 mapp$ )9 an area ( a few squ>e miles ly+ to ! nor? ( ,philip/[n4 ,^! igne\s rocks 7 %[n to =m ,croghan ,hill1 :i*1 ris+ into a conical em95ce #gfi feet above ! sea1 & "s #dej feet above ! g5]al level ( ! great lime/one pla9 ar\nd x1 =ms ! only conspicu\s feature 9 ! l&scape = _m miles4 ,9 ! maps & _! accompany+ ,explanations1 ! gre5/ones are treat$ z intrusive masses1 b ! gre5/one a% or breccia appe>s to h be5 reg>d$ z int]/ratifi$ 9 ! ,c>bonif]\s ,lime/one1 ?\gh ! admission is made t f ! scanty exposures ( ! rocks & ! total abs5ce ( any connect$ section1 x has be5 f\nd impossible to arrive at any def9ite conclusion z to ! relations exi/+ betwe5 ^! traps & a%es ) reg>d to ea* o!r or to ! surr\nd+ lime/one4#gj ,footnote #gj3 ,see ,%eets #aji & #aaj ( ! ,geological ,survey ( ,irel& & ,explanation to accompany ,%eets #ih1 #ii1 #ajh & #aji1 by ,f4 ,j4 ,foote & ,j4 ,o',kelly 7#ahfe71 pp4 #g-ah4 ,9 ! c\rse ( a brief visit to ?is locality ,i did n succe$ 9 obta9+ any c]ta9 pro( ( ! age ( ! igne\s rocks1 b ,i f\nd _! /ructures to be m v>i$ & int]e/+ ?an w\ld be inf]r$ f ! way 9 :i* !y h be5 mapp$1 & ,i came to ! conclusion t ! /rong balance ( probability 0 9 fav\r ( reg>d+ !m z ( ! age ( ! ,c>bonif]\s ,lime/one4 ,illu/ration3 ,fig4 #aib4--;,croghan ,hill1 ,k+'s ,c\nty1 f ,s4,s4,w4 ,! fir/ & mo/ important fact to be ann\nc$ reg>d+ ! di/rict is t x includes a gr\p ( volcanic necks :i* rise ?r\gh ! ,c>bonif]\s ,lime/ones4 ,! *ief ( ^! =ms ,croghan ,hill4 ,x is ne>ly circul> 9 gr\nd-plan1 & measures ab\t #djjj feet 9 diamet] f ! lime/one on "o side to t on ! o!r4 ,x rises ) /eep grassy slopes out ( ! pla91 ! nak$ rock project+ "h & !re 9 crags & l[ cliffs4 ,its g5]al outw>d resemblance to ! ,c>bonif]\s necks ( ,scotl& /rikes ! eye ( ! geologi/ z he approa*es x 7,fig4 #aib74 ,b ,croghan ,hill1 ?\gh ! *ief1 is n ! only v5t ( ! di/rict4 ,x =ms ! c5tre r\nd :i* a gr\p ( subsidi>y v5ts has be5 op5$4 ,^! =m small] & l[] em95ces1 ! mo/ di/ant be+ "o & a half miles ,e4,s4,e4 f ! summit ( ,croghan ,hill1 & measur+ approximately #abjj feet 9 its longe/ & #hjj feet 9 its %orte/ diamet]4 ,t ! igne\s mat]ials ( ^! necks really break ?r\gh ! lime/ones may be cle>ly se5 9 sev]al sections4 ,?us by ! roadside at ,gorte51 on ! s\?-we/]n side ( ,croghan ,hill1 ! lime/ones h be5 ?r[n into a highly incl9$ position1 dipp+ t[>ds ! ea/ at #fj or m1 & _! truncat$ ends abut aga9/ ! side ( ! neck4 ,aga91 on ! ea/]n side ( ! same hill ! lime/ones h be5 mu* di/urb$ close to ! m>g9 ( ! neck1 sometimes dipp+ t[>ds ! volcanic c5tre1 & sometimes /rik+ at x4 ,among ^! /rata a small neck ( breccia1 ( :i* only a few squ>e y>ds are visible1 rises close to ! edge ( ! bog t cov]s ! adjac5t "p ( ! great pla94 ,! mat]ial :i* *iefly =ms ^! necks is "o ( ! mo/ rem>kable breccias any:]e to be f\nd 9 ! volcanic records ( ! ,briti% ,isles4 ,! fir/ feature noticeable 9 x is ! pumice\s "* ( its compon5t fragm5ts4 ,^! consi/ ( a pale blui%-grey basic pumice1 & are g5]ally ab\t ! size ( a hazel-nut1 b desc5d to m]e microscopic du/1 :ile sometimes exce$+ a foot 9 l5g?4 ,!y are angul>1 subangul> & r\nd$4 ,occasionally !y /& out z holl[ %ells on wea!r$ surfaces1 & 9 "o in/ance ,i not$ t ! vesicles 7 flatt5$ & drawn out p>allel to ! surfaces ( ! %ell1 z if de=m$ by gyration1 l a true bomb4 ,! breccia rema9s s+ul>ly uni=m 9 "* ?r\gh\t all ! necks4 ,its basic pumice pres5ts mu* resemblance to t s *>act]i/ic ( ! ,c>bonif]\s necks ( ,scotl&1 ,d]by%ire & ! ,isle ( ,man4 ,! abundant vesicles are g5]ally sph]ical1 & z !y h be5 fill$ ) calcite or *lorite1 !y look l small se$s scatt]$ ?r\gh a grey pa/e4 ,?\gh ,i broke hundr$s ( ! lapilli1 ,i did n notice among !m any volcanic rock o!r ?an ?is pumice4 ,i am n aw>e ( any o!r neck s homog5e\sly fill$ up ) "o type ( pyrocla/ic mat]ial1 & c]ta9ly !re is no o!r example kn[n 9 ! ,briti% ,isles ( s l>ge & uni=m a mass ( fragm5t>y pumice4 ,lime/one fragm5ts are n uncommon 9 ?is breccia4 ,!y resemble ! /rata ar\nd ! v5ts4 ,pieces ( ! adjac5t *]ts may also be obs]v$4 ,9 "o or two cases1 ! lime/one fragm5ts 7 f\nd by me to h an exceptionally cry/all9e texture1 :i* may possibly indicate a c]ta9 degree ( m>m>osis1 b on ! :ole !re is little trace ( alt]ation4 ,! fragm5ts ( pumice 9 ! breccia are b\nd toge!r by a cem5t ( calcite4 ,9 fact ! rock is1 s to speak1 saturat$ ) calc>e\s mat]ial1 :i*1 besides fill+ up ! int]/ices betwe5 ! lapilli1 has p]meat$ ! pumice & fill$ up su* ( its vesicles z are n occupi$ by "s *loritic infiltration4 ,i did n obs]ve unmi/akable evid5ce t any "p ( ! breccia is /ratifi$ & int]calat$ among ! lime/ones1 nor any ve/ige ( a%y mat]ial 9 ^! lime/ones4 ,b x is possible t traces ( su* int]/ratification may occur 9 ! l[ gr\nd to ! nor?-we/ ( ,croghan ,hill1 :i* ,i did n exam9e4 ,9 only two places did ,i notice ev5 a semblance ( ! int]calation ( lime/one 9 ! breccia4 ,"o ( ^! is at ,gorte51 :]e a b& ( lime/one /rata a few feet ?ick is und]la9 & ov]la9 by breccia4 ,b ?\gh ! sup]position ( ! lay]s ( f9ely /ratifi$ d>k lime/one & *]t on ! breccia is well se5 & ?or\ghly def9$1 no lapilli or a%y mat]ial are to be se5 9 ! lime/one4 ,deta*$ pieces ( simil> lime/one & *]t occur 9 ! breccia4 ,! b& ( /ratifi$ rock1 if 9 situ1 may be a tongue project+ f ! wall into ! body ( ! neck1 l "s in/ances already cit$ f ,scotl&1 b m probably x is really a l>ge includ$ mass ly+ )9 ! v5t itself4 ,! breccia "h z else:]e is entirely )\t any trace ( /ratification4 ,! second locality occurs at ! mo/ ea/]ly neck nor? ( ,coole ,h\se1 :]e ! lime/ones1 rapidly undulat+1 seem at la/ to plunge bel[ ! breccia1 :i* %[s a s]ies ( p>allel divisional planes sugge/ive ( b$d+4 ,b ^! may be only jo9t-/ructures1 = !re is no /ratification ( ! compon5t mat]ials ( ! rock4 ,9 ! necks1 & also ?r\gh ! lime/one surr\nd+ !m1 masses ( eruptive rock h be5 intrud$ z irregul> bosses & ve9s4 ,! mat]ial ( ^! intrusions pres5ts little v>iety1 &1 s f> z ,i c\ld note1 gives no indication ( ! successive protrusion ( progressively diff]5t lava4 ,x v>ies f a deep blue-black f9e-gra9$ basalt to a dol]ite :]e ! plagioclase is di/9ct4 ,"s portions1 h[ev]1 are m basic & pass into limburgite4 ,ext]nally !re is no?+ wor?y ( special rem>k 9 ^! rocks unless x be _! preval5t amygdaloidal /ructure4 ,! amygdales1 g5]ally ( calcite1 v>y f small pea-l =ms 9 ! basalts up to k]nels half an in* long or m 9 ! dol]ites4 ,f a microscopic exam9ation ,mr4 ,watts f\nd t "s ( ! basalts h a base ( felsp> & augite ri* 9 br[n mica1 & t _! porphyritic felsp>s enclose idiomorphic cry/als ( augite4 ,p]haps ! mo/ noticeable feature 9 ^! lat] p>ts ( ! volcanic s]ies is ! occurr5ce 9 !m at "o locality 9 ,croghan ,demesne ( lumps ( a highly cry/all9e mat]ial q di/9ct f ! surr\nd+ rock4 ,^! enclosures v>y f an in* or two to a foot or m 9 diamet]4 ,!y mu/ be reg>d$ z blocks :i* h be5 c>ri$ up 9 ! asc5t ( ! basic lava4 ,_! composition has be5 asc]ta9$ by ,mr4 ,watts f microscopic exam9ation to be some:at s+ul>4 ,"o specim5 conta9s relics ( g>nets1 surr\nd$ by r+s ( kelyphite1 imb$d$ 9 a mosaic ( felsp>1 ) a m9]al :i* may possibly be idocrase4 ,ano!r specim5 f ! same locality 7s\?-ea/ f ,gorte57 conta9s ! relics ( g>nets pres]v$ z kelyphite1 set 9 a matrix ( qu>tz-gra9s1 mu* /ra9$1 & conta9+ a pr(usion ( cry/als ( gre5i%-yell[ or r$ sillimanite4 ,?is appe>s to be a metamorphic rock1 & may be a fragm5t ( "s s$im5t enclos$ 9 ! igne\s rocks4#ga ,footnote #ga3 ,guide to ! ,collections ( ,rocks & ,fossils belong+ to ! ,geological ,survey1 9 ! ,museum ( ,sci5ce & ,art1 ,dubl9 7#ahie71 pp4 #ch1 #ci4 ,z reg>ds ! hi/ory ( volcanic action 9 ,brita9 "o ( ! *ief po9ts ( int]e/ connect$ ) ^! ,iri% breccias & lavas relates to _! geological age4 ,z no pro( has be5 produc$ t any portion ( !m is contemporane\sly int]/ratifi$ 9 ! ,c>bonif]\s ,lime/one :i* surr\nds !m1 we _c def9itely affirm t ! volcanic eruptions :i* !y record took place dur+ ! accumulation ( t =mation4 ,! v5ts mu/1 ( c\rse1 be lat] ?an t portion ( ! lime/one :i* !y pi]ce4 ,b ! evid5ce seems to me to be on ! :ole mo/ fav\rable to ! view t !y are ( ,c>bonif]\s ,lime/one age1 = ! foll[+ reasons3-- #a4 ,! breccias ( ,croghan ,hill d n pres5t a resemblance to any ( ^? belong+ to ! ,t]ti>y volcanic s]ies 9 ,antrim or ! ,inn] ,hebrides4 ,! possibility ( _! be+ ( ,t]ti>y age may !re=e be dismiss$ f consid]ation4 #b4 ,!re are no kn[n ,p]mian volcanic rocks 9 ,irel&4 ,nor does ! ,croghan ,hill breccia %[ any resemblance to ! ord9>y mat]ial ( ! breccias 9 ! ,p]mian necks ( ,scotl&4 ,x is ?us n likely to be ( ,p]mian age4 #c4 ,! peculi> basic pumice ( ^! ,croghan ,hill v5ts has _m po9ts 9 common ) ! palagonite fragm5ts s abundant among ! volcanic breccias & tuffs ( ,c>bonif]\s age 9 ,scotl&1 ,d]by%ire1 & ! ,isle ( ,man1 & :i* occurs also among ! ,c>bonif]\s tuffs ( ! ,lim]ick bas94 ,x diff]s f ! g5]al type ( ! mat]ial 9 its pale col\r1 9 its uni=mity ( "*1 9 its calc>e\s cem5t1 & above all 9 its va/ prepond]ance ov] all ! o!r mat]ials 9 ! breccia4 #d4 ,! saturation ( ! ,croghan ,hill breccia ) calcite is a s+ul> feature 9 ! composition ( ! rock4 ,_h ! v5ts be5 op5$ long subsequ5t to ! deposition ( ! ,c>bonif]\s ,lime/one1 x is difficult to und]/& h[ ?is calcite c\ld h be5 introduc$4 ,m]e p]colation ( meteoric wat] f ! adjac5t lime/one does n seem adequate to acc\nt = ! scale & ?or\ghness ( ! p]meation4 ,b if ! v5ts 7 op5$ on ! floor ( ! ,c>bonif]\s ,lime/one sea1 x is intelligible t mu* f9e calc>e\s silt %\ld h f\nd its way d[n among ! int]/ices ( ! breccia & into ! pores ( ! pumice :i*1 be+ cak$ toge!r )9 ! v5t1 did n all float away :5 ! sea ga9$ access to ! volcanic funnel4 ,! effect ( subsequ5t p]colation w\ld d\btless be to c>ry ! lime into /ill unfill$ crevices1 & to imp>t to ! cem5t a cry/all9e /ructure simil> to t :i* has be5 develop$ 9 ! ord9>y lime/ones4 #b4 ,,! ,,lim]ick ,,bas9 ,ab\t #gj miles to ! s\?-we/ ( ! area j describ$ lies ! mo/ compact1 &1 = its size1 "o ( ! mo/ v>i$ & complete1 ( all ! ,c>bonif]\s volcanic di/ricts ( ,brita9 7,map ,i474 ,x takes ! =m ( an oval bas9 9 ! ,c>bonif]\s ,lime/one s]ies ne> ! t[n ( ,lim]ick1 ab\t twelve miles long f ea/ to we/ & six miles broad f nor? to s\?4 ,r\nd ?is bas9 ! volcanic rocks ext5d z a rim ab\t a mile broad4 ,a portion ( a second or inn] rim1 m>k+ a second & high] volcanic gr\p1 p>tially encloses a pat* ( ,mill/one ,grit or ,coal-measures1 :i* lies 9 ! he>t ( ! lime/one bas94 7,see ! section 9 ,fig4 #aif47 ,b x is evid5t t1 z ! d5ud$ edges ( ! volcanic %eets em]ge at ! surface all r\nd ! bas91 ! pres5t area ov] :i* ^! rocks ext5d mu/ be consid]ably less ?an t :i* !y orig9ally cov]$4 ,"s indication ( _! great] ext5sion is suppli$ by outli]s ( ! b$d$ lavas & tuffs1 z well z by bosses :i* d\btless indicate ! position ( "s ( ! eruptive v5ts4 ,! di/ance betwe5 ! fur!/ rema9+ pat*es is #bd miles4 ,! orig9al tract ov] :i* ! volcanic mat]ials 7 spread _c h be5 less ?an #bd miles long by #aj miles broad4 ,if we assume its area to h be5 betwe5 #bej & #cjj squ>e miles we %all probably be "u ! tru?4 ,?is volcanic c5tre made its appe>ance on ! floor ( ! ,c>bonif]\s ,sea 9 ! same di/rict :i* _h witness$ ! eruptions ( ,upp] ,old ,r$ ,s&/one "t4 ,! two visible v5ts t cr[n ! ,knockfe]9a & ,ball9le5y anticl9es 7,*apt] xxii471 are only "s t5 miles di/ant1 & !re may be o!rs ( ! same age ev5 "u ! ,lim]ick bas94 ,?is di/rict ?us supplies ano!r in/ance ( t recurr5ce ( volcanic en]gy 9 ! same area1 aft] a long] or %ort] geological int]val1 :i* /&s out z a conspicu\s feature 9 ! hi/ory ( volcanic action 9 ,brita94 ,t a prolong$ int]val elaps$ betwe5 ! ext9ction ( ! ,old ,r$ ,s&/one volcanoes & ! outbreak ( _! successors dur+ ! accumulation ( ! ,c>bonif]\s lime/one s]ies1 may be inf]r$ f ! ?ickness ( /rata :i* sep>ate _! respective tuffs4 ,f ! publi%$ sections ( ! ,geological ,survey !re w\ld appe> to be ab\t #ejj feet ( ,old ,r$ ,s&/one above ! volcanic s]ies ( t =mation4 ,!n comes ! ,l[] ,lime/one %ale1 :i* is comput$ to be ab\t ! same ?ickness4 ,f ! sc>city ( obs]vable dip among ! ,l[] ,lime/ones & _! v>iable incl9ation1 x is n easy to =m any satisfactory e/imate ( ! dep? ( ?is gr\p up to ! base ( ! volcanic s]ies4 ,x may be z mu* z #hjj feet1#gb & if s !re w\ld ?us int]v5e a mass ( s$im5t>y mat]ial ne>ly #bjjj feet 9 ?ickness betwe5 ! two volcanic plat=ms4 ,?r\gh\t ?is ?ick accumulation ( /ratifi$ deposits no trace ( contemporane\s volcanic activity has be5 detect$4 ,f ! descriptions publi%$ m ?an ?irty ye>s ago by ,jukes & 8 colleagues 9 ! ,geological ,survey ( ,irel&1 geologi/s le>nt h[ full & int]e/+ are ! pro(s ( great volcanic activity contemporane\s ) ! deposition ( ! ,c>bonif]\s ,lime/one s]ies 9 ! ,lim]ick di/rict4#gc ,n[h]e1 inde$1 is ! evid5ce m complete = ! occurr5ce ( a long succession ( volcanic eruptions dur+ a def9ite p]iod ( geological "t4 ,! (fic]s ( ! ,survey %[$ t two epo*s ( activity dur+ ! old] "p ( ! ,c>bonif]\s p]iod 7 ea* m>k$ by a gr\p ( tuffs & lavas1 :ile ! int]val ( quiesc5ce betwe5 !m is repres5t$ by a ?\s& feet ( lime/one4 ,! same obs]v]s likewise mapp$ outside ! volcanic r+ a numb] ( eruptive bosses1 :i* !y reg>d$ z probably m>k+ "s ( ! actual v5ts ( t "t4 ,footnote #gb3 ,?is is ! ?ickness giv5 9 ! ,explanation to ,%eet #add ( ! ,geological ,survey ( ,irel&1 p4 #h4 ,a /ill great] ?ickness is claim$ 9 ,explanation to ,%eet #aed1 p4 #h4 ,footnote #gc3 ,see especially ,explanations ( ,%eets #adc1 #add1 #aec & #aed1 ,geol4 ,surv4 ,irel& 7#ahfj1 #ahfa74 ,! geology ( ! di/rict _h be5 previ\sly notic$ by e>li] obs]v]s1 to ^: writ+s ref]5ce is made on p4 #bf ( ! ,explanation ( ,%eet #add4 ,see also ,jas4 ,apjohn1 ,j\rn4 ,geol4 ,soc4 ,dubl91 vol4 i4 7#ahcb71 p4 #bd2 ,pr(4 ,hull1 ,geol4 ,mag4 = #ahgd1 p4 #bje4 ,jukes 7,/ud5t's ,manual ( ,geology1 #bnd edit4 #ahfb1 p4 #cbe7 gave subsequ5tly an excell5t epitome ( ! volcanic hi/ory4 ,! microscopic /ructure ( "s ( ! ,lim]ick volcanic rocks has be5 describ$ by ,mr4 ,allport1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xxx4 7#ahgd71 p4 #eeb1 & by ,pr(4 ,hull1 ,geol4 ,mag4 = #ahgc1 p4 #aec4 ,see also ,mr4 ,watts' acc\nt ( ^! rocks 9 ! ,guide to ! ,collections ( ,rocks & ,fossils 7,dubl91 #ahie71 p4 #ic4 ,! l[] volcanic gr\p1 :i* =ms a complete r+ r\nd ! ,upp] ,lime/ones ( ! ,lim]ick bas91 is e/imat$ to rea* a ?ickness ( #ajjj feet 9 "s p>ts ( its c\rse4#gd ,its base appe>s to co9cide g5]ally ) ! upw>d t]m9ation ( ! ,l[] ,lime/one gr\p ( ?is di/rict1 ?\gh "h & !re small pat*es ( volcanic rocks 9 t gr\p h be5 reg>d$ z int]/ratifi$ & contemporane\s b&s4#ge ,x consi/s ( a s]ies ( lavas & tuffs1 ! alt]nations & rapid incom+ & dy+ out ( :i* 7 well made out by ! ,geological ,survey4 ,footnote #gd3 ,explanation ( ,%eet #add1 p4 #bg4 ,footnote #ge3 ,"s ( !m1 h[ev]1 h *>act]s t r seem to place !m ) ! intrusive mat]ials ( ! di/rict1 & !re=e n necess>ily e>li] ?an ! b$d$ lavas & tuffs4 ,! b\nd>y l9e ( ! volcanic s]ies is n consi/5tly foll[$ along ! same horizon on ! ,survey maps4 ,?us to ! ea/ ( ,cah]conli%1 a /rip ( ! ,upp] ,lime/one is ins]t$ bel[ ! base ( ! tuffs = a di/ance ( ab\t f\r miles4 ,unless a diff]5t horizon has be5 9 "s places tak5 = ! b\nd>y betwe5 ! two gr\ps ( lime/ones1 x w\ld appe> t ! eruptions _h n ext5d$ ov] ! nor? & nor?-ea/ ( ! di/rict until "s "t aft] ! deposition ( ! ,upp] ,lime/one _h begun4 ,! division betwe5 ! two lime/one gr\ps is tak5 at a set ( *]t-b&s1 b z ^! are n con/ant x is sometimes difficult to draw a satisfactory l9e ( division4 ,tuffs4--,! base ( ! volcanic s]ies is g5]ally =m$ by a b& ( tuff sometimes z mu* z #cej feet ?ick1#gf :i* may be trac$ ne>ly cont9u\sly r\nd ! bas9 z well z 9 deta*$ outli]s ev5 z f> z ,c>rigogunnel ov]look+ ! alluvial pla9 ( ! ,%annon4 ,! mann] 9 :i* ! bottom ( ?is tuff is int]/ratifi$ ) ! lime/one bel[ x may be in/ructively exam9$ 9 _m qu>ries ar\nd ! t[n ( ,lim]ick4 ,/rik+ evid5ce is !re suppli$ t ! fir/ eruptions 7 comp>atively feeble & spasmodic1 & 7 sep>at$ by int]vals ( long] & %ort] duration1 dur+ :i* ! lime/one ) its fragm5t>y organisms 0 deposit$1 little or no volcanic detritus fall+ at t "t4 ,yet ev5 9 "s ( ! lime/ones ! microscope reveals f9e brok5 ne$les ( felsp>1 repres5t+ d\btless ! f9e/ eject$ du/4#gg ,footnote #gf3 ,explanation ( ,%eet #aed1 p4 #ba4 ,footnote #gg3 ,= ! details ( ! microscopic /ructure ( ! ,lim]ick volcanic rocks ,i am ma9ly indebt$ to ! exam9ation ( !m made = me by my ,survey colleague1 ,mr4 ,w4 ,w4 ,watts4 ,z an illu/ration ( ! way 9 :i* ! volcanic & organic detritus alt]nat$ ov] ! sea-floor1 ! foll[+ section f a qu>ry 9 ! t[nl& ( ,lo* ,gur on ! s\!rn side ( ! bas9 is "h giv53#gh-- ,footnote #gh3 ,explanation ( ,%eet #aed1 pp4 #ba1 #bb4 ,*]ty lime/one m ?an #bj feet #j 94 ,decompos$ gre5 tuff #b #f ,blui%-gre51 calc>e\s lam9at$ tuff #d #j ,lime/one1 slightly a%y #a #h ,gre5 tuff #j #b ,f9e-gra9$ decompos$ tuff #j #d ,gre5 tuff1 obliquely lam9at$ #a #g ,f9e lam9at$ tuff #j #h ,gre5 compact tuff #a #h ,obliquely lam9at$ %aly tuff #j #aj ,concretion>y a%y lime/one #a #d ,compact a%y lime/one #b #j ,gre5 %aly tuff1 mu* wea!r$ #j #e ,a%y lime/one #j #g ,compact gre5 tuff m ?an #d #j -------------- #da feet #i 94 ,! tuffs :i* 9 ! s\!rn "p ( ! bas9 und]lie ! less basic lavas diff] 9 "s respects f ^? :i* fur!r nor? are associat$ ) ! ,upp] ,lime/ones4 ,!y are gre51 sometimes dull purpli%-r$1 f9ely granul> rocks1 made up 9 l>ge "p ( &esitic debris4 ,!y are full ( loose felsp> cry/als1 m9ute1 some:at r\nd$ & subangul> lapilli ( &esite or "s less basic lava1 toge!r ) bits ( grit & bak$ %ale4 ,?\gh g5]ally mu* decompos$1 !y are sometimes compact en\gh to be us$ = build+-/one4 ,"u ! microscope ^! tuffs are se5 to ab\nd 9 &esite-lapilli1 ) a few pieces ( felsitic rocks enclos$ 9 an opaque base1 ?r\gh :i* are scatt]$ brok5 felsp>s & occasional vesicul> lapilli4 ,illu/ration3 ,fig4 #aic4--,section 9 qu>ry on roadside ea/ ( ,lim]ick close to viaduct ( ! ,lim]ick & ,erris ,railway4 #a4 ,lime/one2 #b4 ,calc>e\s tuff2 #c4 ,a%y lime/one or calc>e\s tuff4 ,! tuffs ar\nd ,lim]ick1 int]b$d$ ) ! ,black 7,upp]7 ,lime/one1 are di/+ui%$ by a sc>city ( &esitic debris1 by _! p]si/5t dull gre5i%-grey col\r1 & m p>ticul>ly by ! abundance ( m9ute lapilli & l>g] fragm5ts ( an epidote-gre51 f9ely vesicul>1 easily sectile basic pumice4 ,"u ! microscope mu* ( ?is mat]ial is f\nd to be an alt]$ basic glass ( ! nature ( palagonite4 ,^! tuffs are 9 evid5t relation ) ! m basic lavas t accompany !m4 ,! mann] 9 :i* !y alt]nate ) ! black lime/one %[s t ! conditions = ! eruption ( ?is m basic detritus cont9u$ to be v simil> to ^? t exi/$ :5 ! &esitic tuffs 7 eject$4 ,z a good illu/ration ( ?is feature ! accompany+ section 7,fig4 #aic7 is giv5 f a qu>ry on ! side ( ! high-road betwe5 ,lim]ick & ,annacotty4 ,! total dep? ( /rata "h repres5t$ is ab\t #ae feet4 ,! black lime/one at ! bottom is a tol]ably pure calc>e\s rock4 ,x is divid$ into b&s by ?9 p>t+s ( a f9e gre5i% calc>e\s tuff1 ea* m>k+ a brief dis*>ge ( a%es f "s neighb\r+ v5t4 ,half-way up ! succession ( /rata1 ! a%y mat]ial rapidly increases until x usurps ! place ( ! lime/one1 ?\gh its calc>e\s composition %[s t ! accumulation ( calc>e\s s$im5t _h n be5 entirely susp5d$ dur+ ! eruption ( a%4 ,among ^! tuffs ,i h notic$ fragm5ts ( f9e1 d>k1 fl9ty felsite1 grit & o!r rocks4 ,! /ones are = ! mo/ "p small1 b v>y up to blocks occasionally a foot 9 diamet]4 ,lavas4--,! lavas occur 9 num]\s %eets1 sometimes sep>at$ by ?9 p>t+s or ?ick] b$s ( tuff & volcanic conglom]ate4 ,on ! nor!rn rim ( ! bas9 ,mr4 ,g4 ,h4 ,k9ahan has describ$ ! volcanic s]ies ea/ ( ,%ehan's ,cross-roads z compos$ ( six zones ( tuff1 ea* b$ v>y+ f ab\t #ej to #bej feet 9 ?ickness1 alt]nat+ ) z _m %eets ( lava rang+ f #bg to #ahj feet 9 ?ickness1 ! total dep? ( tuff be+ e/imat$ at ne>ly #ejj feet & t ( ! lavas at ab\t #hjj feet4#gi ,"s ( ^! tuffs are co>se conglom]ates or agglom]ates1 ) blocks ( lava occasionally #aj feet long4 ,footnote #gi3 ,explanation ( ,%eet #add1 p4 #bh4 ,"s ( ! lavas 9 ! l[] volcanic gr\p are &esites q l ^? ( ! plateau s]ies 9 ! ,c>bonif]\s sy/em ( ,scotl&4 ,ext]nally !y appe> z dull r$di%-br[n or purpli%-r$ compact rocks1 ) abundant porphyritic felsp>s scatt]$ ?r\gh ! f9e-gra9$ base4 ,!y are g5]ally mu* decompos$1 %[+ on a fre% fracture pseudomorphs ( *lorite1 hmatite & calcite aft] "s ( ! m9]als1 ) abundant hmatitic /a9+ ?r\gh ! body ( ! rock4 ,amygdaloidal /ructure is commonly develop$4 ,^! &esites1 :5 exam9$ microscopically1 7 f\nd by ,mr4 ,watts to pres5t ! *>act]i/ic base ( m9ute felsp>-la?s ) magnetite & en/atite1 & ) porphyritic cry/als1 (t5 l>ge1 ( zon$ plagioclase1 z well z ( ilm5ite & hmatite4 ,illu/ration3 ,fig4 #aid4--,section ( ! volcanic esc>pm5t1 ea/ ( ,%ehan's ,cross-roads1 s\? ( ,lim]ick4 #a4 ,lime/one2 #b #b4 ,tuffs2 #c #c4 ,lavas4 ,b besides ! &esites !re occur also1 &1 s f> z ,i h obs]v$1 9 l>g] numb]1 %eets ( true basalt4 ,?is rock is typically black1 exce$+ly close-gra9$ 9 ! c5tral portion ( ea* %eet1 b becom+ highly slaggy & vesicul> along ! upp] & l[] p>ts4 ,"u ! microscope x is f\nd to conta9 granul> augite & magnetite1 set 9 a m or less devitrifi$ glass1 ) microlites ( felsp>1 porphyritic plagioclase1 s]p5t9iz$ oliv9e1 & "s well-m>k$ augite4 ,^! rocks =m di/9ct esc>pm5ts along ! nor!rn rim ( ! bas9 z 9 ! =ego+ section ea/ f ,%ehan's ,cross-roads 7,fig4 #aid74 ,f ! summit ( ?is ridge1 :i* is ab\t #fjj feet above ! sea1 ! eye looks nor?w>d ov] ! pla91 across :i* l[ outli]s ( ! volcanic s]ies are scatt]$1 & s\?w>ds across ! bas9 to ! correspond+ l9e ( volcanic heights =m+ ! s\!rn rim4 ,! upp] volcanic gr\p has be5 e/imat$ by ! (fic]s ( ! ,geological ,survey to lie ab\t #ajjj feet high] 9 ! ,c>bonif]\s sy/em ?an ! l[]1 ! int]v5+ /rata consi/+ ( ! ,upp] ,lime/one4#hj ,x is possible t ! int]val is great] 9 "s p>ts ( ! di/rict ?an 9 o!rs1 & if s1 ! diff]5ce may be due ei!r to great] local accumulation ( volcanic mat]ials1 or to local prolongation ( ! eruptions into high] /ratigraphical horizons4 ,! outcrop ( ! upp] volcanic b& =ms ab\t half ( a r+ r\nd ! little cup ( ,mill/one ,grit or ,coal-measures :i* lies )9 ! volcanic bas94 ,on ! nor?-we/ side ( ! cup ! volcanic rocks disappe>4 ,h5ce ! upp] b& has a mu* m re/rict$ area ?an ! l[]4 ,b if ! tuffs imm$iately ar\nd ,lim]ick are assign$ to ! upp] gr\p1 its ext5t w be proportionately increas$4 ,!re c be little d\bt1 h[ev]1 t nei!r 9 ?ickness nor 9 sup]ficial area did ! lavas & tuffs ( ! second gr\p equal ^? ( ! fir/4 ,! volcanic en]gy 0 gradually dy+ out4 ,footnote #hj3 ,explanation ( ,%eet #aed1 p4 #bd4 ,! lavas ( ! second p]iod are *>act]i/ic dull1 black1 compact basalts1 l ^? ( ! fir/ p]iod1 becom+ "h & !re /rongly amygdaloidal1 & be+ occasionally sep>at$ by slaggy or conglom]atic p>t+s4 ,b !y include also c]ta9 rocks :]e9 ! felsp> dim9i%es 9 quantity1 :ile augite & oliv9e become conspicu\s1 toge!r ) a little en/atite4 ,! augite occurs 9 l>ge porphyritic =ms1 z well z ( m$ium size & 9 small prisms4 ,! oliv9e1 z usual1 is n[ 9 ! condition ( s]p5t9e4 ,^! rocks are m basic ?an ! ord9>y basalts1 conta9+ only #chff p] c5t ( silica1 & ?us approa*+ ! limburgites4 ,) ^! basic lavas are associat$ dull gre5 tuffs & conglom]ates1 made up l>gely ( basalt-debris1 toge!r ) abundant pieces ( f9ely vesicul> basic pumice & lapilli ( a palagonitic mat]ial4 ,! mann] 9 :i* ! lavas & tuffs h alt]nat$ ) ea* o!r1 & also ) ! lime/ones1 is well se5 on ,nick] ,hill above ,pallas ,grean4#ha ,! ,survey sections %[ eight %eets ( lava1 sep>at$ by six b&s ( tuff & eight int]calations ( lime/one1 ! :ole pass+ "u ! ,coal-measures4 ,footnote #ha3 ,see ,explanation ( ,%eet #add1 p4 #cj1 :]e a description ) detail$ map & sections ( ?is gr\nd w be f\nd4 ,! upp] volcanic gr\p may be z mu* z #fjj or #hjj feet ?ick4 ,x appe>s to h be5 left1 at ! close ( ! eruptions1 ) a v unev5 surface1 "s portions be+ s l[ z to be ov]spread ) ! ,upp] ,lime/ones1 o!r p>ts s high z n to be cov]$ until ! ,coal-measure %ales & flag/ones came to be deposit$4#hb ,footnote #hb3 ,explanation ( ,%eet #aed1 pp4 #bd1 #ce4 ,v5ts4--,all r\nd ! edges ( ! ,lim]ick bas91 :]e ! esc>pm5ts ( ! volcanic gr\ps1 ris+ abruptly above ! pla91 %[ t ^! rocks once ext5d$ beyond _! pres5t limits1 ! progress ( d5udation has reveal$ a numb] ( bosses :i*1 z above /at$1 ,jukes & 8 associates look$ ^u z m>k+ "s ( ! v5ts f :i* ! lavas & tuffs 7 erupt$4 ,especially /rik+ is ! l9e ( ^! v5ts along ! s\!rn m>g94 ,! rocks n[ fill+ !m pres5t "s unusual & r anomal\s features4 ,!y are decid$ly m acid ?an ! lavas ( ! bas91 "s ( !m ev5 conta9+ free qu>tz4 ,mr4 ,watts rem>ks t ?\gh !y h a good deal 9 common ) ! tra*ytes1 !y are cry/all9e ?r\gh\t4 ,!y are r$ granite-look+ rocks1 :i* are made up *iefly ( /umpy idiomorphic prisms ( felsp> :i* is ma9ly or?oclase4 ,"s plagioclase also occurs1 & ! two felsp>s are imb$d$ 9 int]/itial qu>tz4 ,a trace ( hornbl5de or mica is frequ5tly pres5t1 & ! rocks conta9 ab\t #fe p] c5t ( silica4 ,^! *>act]s are specially obs]vable 9 ! necks fur!/ remov$ f ! bas91 :i* may possibly h be5 connect$ ) ! &esitic outfl[s4 ,ne>] to ! bas9 ! necks conta9 ab\t #fj p] c5t ( silica1 seldom %[ any int]/itial qu>tz1 & /& betwe5 tra*ytes & porphyrites1 "s p]haps be+ bo/onites4#hc ,footnote #hc3 ,guide to ! ,collections ( ,rocks1 etc41 ,geol4 ,survey1 ,irel&1 p4 #ic1 ,dubl9 #ahie4 ,illu/ration3 ,fig4 #aie4--,view ( ,d]k ,hill1 a volcanic neck on ! s\? side ( ! ,lim]ick bas94 ,a geologi/1 famili> ) ! ,c>bonif]\s & ,p]mian necks ( ,scotl&1 has no hesitation 9 confirm+ ! surmise ( ,jukes & 8 colleagues t ! cones & domes ar\nd ! ,lim]ick bas9 m>k ! sites ( eruptive v5ts4 ,on ! s\? side ( ! bas91 at lea/ n9e su* necks rise into view1 p>tly f among ! lavas & tuffs1 b *iefly ?r\gh ! lime/ones t em]ge f bel[ ^! volcanic %eets4 ,"o ( ! mo/ conspicu\s ( !m1 ,d]k ,hill 7,fig4 #aie71 rises to a height ( #gha feet above ! sea1 & comes ?r\gh ! b$d$ &esites1 z repres5t$ 9 ,fig4 #aif1 :i* gives1 9 diagrammatic =m1 ! g5]al /ructure ( ! ,lim]ick volcanic bas94 ,ar\nd ! nor!rn side ( ! bas9 a small] numb] ( necks has be5 obs]v$1 consi/+ ( simil> acid rocks4 ,illu/ration3 ,fig4 #aif4--,section across ! ,lim]ick volcanic bas94 #a4 ,l[] lime/one2 #b4 ,l[] s]ies ( lavas & tuffs2 #c4 ,middle & ,upp] ,lime/one2 #d4 ,upp] s]ies ( lavas & tuffs2 #e #e4 ,two volcanic necks2 #f4 ,mill/one ,grit s]ies4 ,a few ( ! necks appe> to be fill$ ) volcanic agglom]ate4 ,"h & !re deta*$ pat*es ( fragm5tal volcanic mat]ial h be5 %[n on ! ,survey maps1 & ref]r$ to 9 ! ,explanations1 z if !y 7 outli]s ( ! b$d$ tuffs2 ?\gh 9 "s cases ! co>s5ess ( _! mat]ials & ! want ( any di/9ct b$d+1 toge!r ) ! abs5ce ( any indication ( _! relation to ! ne>e/ lime/ones1 h evid5tly (f]$ consid]able difficulty 9 _! mapp+4 ,"o ( ! be/ examples occurs ab\t two miles to ! s\?-ea/ ( ! village ( ,oola4 ,! b\nd>ies ( ?is pat*1 z put on ! map1 are confess$ to be entirely speculative4 ,x 0 only se5 on ! side ( ! railway :]e x appe>$ z a v co>se brecciat$ purple a%4#hd ,footnote #hd3 ,explanation ( ,%eet #aed1 p4 #be4 ,on comp>+ ! maps ( ! ,lim]ick bas9 ) ^? ( ! ,c>bonif]\s di/ricts ( ,scotl&1 ! ma9 diff]5ce w probably be ackn[l$g$ to be ! abs5ce ( any recognizable sills 9 ! ,iri% gr\nd4 ,t no sills actually occur1 ,i am n prep>$ to affirm4 ,inde$ "s ( ! m acid rocks1 bo? outside ! bas9 & among ! rocks ( ! old] volcanic gr\p1 appe>$ to me dur+ my trav]ses ( ! gr\nd to h mu* ( ! "* ( sills4 ,a m critical exam9ation ( ! area w\ld n improbably detect "s truly intrusive %eets :i* h hi!rto be5 mapp$ among ! int]/ratifi$ lavas4 ,"s appe> to exi/ among ! surr\nd+ ,l[] ,lime/ones4 ,an intrusive mass1 l a sill or dyke1 is repres5t$ on ! ,geological ,survey ,map z trav]s+ ! ,coal-measures 9 ! inn] bas9 s\? ( ,ballybrood4 ,b z ! /rata are on end along its s\!rn m>g91 x may possibly be only a portion ( ! upp] volcanic s]ies :i* has be5 ?r[n into its pres5t position by "o or m faults4#he ,footnote #he3 ,%eet #aed & ,explanation to ! same1 p4 #bd4 #c4 ,,! ,,volcanic ,,breccias ,,( ,,d\btful ,,age ,,9 ,,c\nty ,,cork ,9 ! s\?-we/]n headl&s ( ,irel&1 f ,be> ,isl& to ,dursey ,isl&1 v>i\s igne\s rocks h be5 trac$ on ! maps ( ! ,geological ,survey4 ,!y h be5 describ$ z consi/+ ( gre5/one1 fel/one1 & a% or breccia1 & z includ+ bo? int]/ratifi$ & intrusive masses4#hf ,if contemporane\s ) ! /rata 9 :i* !y occur1 !y w\ld prove ! exi/5ce ( a gr\p ( volcanic rocks 9 ! ,c>bonif]\s slate1 or l[e/ division ( ! ,c>bonif]\s sy/em4 ,aft] an exam9ation ( ! coa/-l9e ,i came to ! conclusion t :ile !re is und\bt$ly evid5ce ( =m] volcanic activity 9 ?is "p ( ,irel&1 no pro( has be5 obta9$ t ! eruptions occurr$ 9 ! ,c>bonif]\s p]iod4 ,! felsites & dol]ites appe>$ to me to be all intrusive1 ! =m] hav+ c]ta9ly be5 inject$ be=e ! t]re/rial movem5ts t h di/urb$ ! rocks1 = "s ( !m %>e v m>k$ly 9 ! cleavage ( ! region4 ,! dol]ites & diabases1 on ! o!r h&1 s f> z ,i obs]v$1 are n cleav$1 & are ?us probably ( lat] date4 ,footnote #hf3 ,see ,%eets #aig & #aih ( ! ,geological ,survey ( ,irel&1 & ! ,explanation ( ^! ,%eets by ,messrs4 ,jukes1 ,k9ahan1 ,wilson1 & ,o',kelly1 #ahfj4 ,! mo/ int]e/+ rocks are und\bt$ly ! a% & breccia1 = !y are obvi\sly ( volcanic z di/+ui%$ f plutonic orig94 ,on ! coa/ nor? ( ,:ite ,bull ,head1 a b$ ( volcanic breccia may be se5 made up ( r\nd$ & angul> fragm5ts ( diff]5t s&/ones1 %ales & lime/ones1 ) pieces ( felsite & &esite wrapp$ up 9 a dull-grey f9e-gra9$ s&y felspa?ic matrix4 ,! rock wea!rs ) a r\gh or rugg$ surface1 ow+ to ! dropp+ out ( ! m decomposable /ones4 ,?is b$1 ab\t five feet ?ick1 runs ) ! b$d+ ( ! /rata ar\nd x1 & l ^! dips ,s4,s4,w4 at an angle ( #gj4 ,if no o!r evid5ce 7 obta9able1 ?is breccia w\ld be naturally set d[n z a truly int]/ratifi$ deposit ( volcanic detritus4 ,a %ort di/ance f x1 a second1 r ?ick] b& ( simil> mat]ial occurs1 specially di/+ui%$ by its abundant worn cry/als ( hornbl5de1 sometimes ?ree in*es 9 diamet]1 z well z l>ge cry/als ( muscovite4 ,^! m9]als are n unkn[n else:]e 9 volcanic agglom]ates4 ,! occurr5ce ( lumps ( augite 9 ! v5ts ( ,upp] ,old ,r$ ,s&/one age 9 ,cai?ness has be5 already allud$ to1 & a /ill l>g] s]ies ( eject$ m9]als w be %[n 9 a lat] *apt] to *>act]ize ! y\ng] necks ( ,c5tral ,scotl&4 ,9 p>ts ( its c\rse1 ?is second b& appe>s to run s p]fectly p>allel ) ! b$d+ ( ! /rata betwe5 :i* x lies t ! obs]v] w\ld readily believe x to be a "p ( ! same s]ies ( deposits1 & might !re=e reg>d x z af=d+ good evid5ce ( volcanic action contemporane\s ) ! =mation ( ^! deposits4 ,a transv]se section ( ! b$1 :]e ?us app>5tly con=mable1 is %[n 9 ,fig4 #aig4 ,illu/ration3 ,fig4 #aig4--,section ( a b$ ( ,volcanic ,breccia 9 ! ,c>bonif]\s ,slate2 ,:ite ,bull ,head1 ,c\nty ,cork4 #a #a4 ,s&/ones & %ales2 #b4 ,breccia4 ,illu/ration3 ,fig4 #aih4--,volcanic ,breccia invad+ & enclos+ ,c>bonif]\s ,slate1 ,:ite ,bull ,head4 ,fur!r exam9ation1 h[ev]1reveals t ?is seem+ly regul> sequ5ce is entirely deceptive4 ,at v>i\s po9ts ! breccia abruptly truncates ! s&/ones1 & involves l>ge pieces ( !m1 z %[n 9 ,fig4 #aih ,a4 ,at o!r places1 ! l[] side ( ! breccia1 or :at w\ld be its base if x 7 a regul> b$1 cuts out ! /rata & s5ds ve9s into !m 7,b74 ,& ! same /ructure is visible1 on its upp] side1 or :at w\ld be its top 7,c74 ,x is cle> t ^! highly-incl9$ b&s ( breccia are n contemporane\s ) ! deposition ( ! ,c>bonif]\s ,slate1 b h be5 introduc$ into _! position at "s "t subsequ5t n only to ! deposition1 b to ! di/urbance & elevation ( ! /rata4 ,! p59sula ( ,:ite ,bull ,head is cross$ by sev]al o!r simil> b&s4 ,on ,black ,bull ,head1 also1 toge!r ) abundant felsitic & dol]itic intrusions1 a simil> breccia or agglom]ate is to be se54 ,9 "s p>ts x is compact 9 texture ) sph]oidal fl9ty lumps1 & wea!rs some:at l a nodul> felsite4 ,?is v>iety ends (f r abruptly to ! nor?1 b swells out s\?w>d1 & !n runs out into a high1 n>r[ headl&1 9 :i* x conta9s asbe/os1 z well z r\nd$ cry/als ( hornbl5de4 ,x has "h disrupt$ ! %ales & s&/ones1 & ne> ! junction is l>gely compos$ ( fragm5ts ( !m1 ! /rata !mselves be+ jumbl$1 b5t1 & brok5 up4 ,! only semblance ( a neck-l mass ( ?is volcanic fragm5tal mat]ial occurs on ,:ite ,bull ,head1 :]e "o ( ! b&s exp&s ab\t ! c5tre ( ! ridge1 & is !re full ( l>ge blocks ( grey s&/one4 ,! breccia appe>s to h fill$ fissures :i* h be5 op5$ betwe5 ! b$d+ planes ( ! highly tilt$ /rata1 giv+ rise to long n>r[ dyke-l int]calations4 ,we h se5 t among ! ,c>bonif]\s volcanic ph5om5a su* dyke-l masses ( agglom]ate occasionally pres5t !mselves 9 ! v5ts bo? ( ! plateaux & ! puys4 ,9 "o or two places ,i notic$ :at may be traces ( cleavage 9 ! breccia4 ,! rock is n "o t w\ld yield easily to ! re>rangem5ts requir$ = ! production ( ?is /ructure1 & ! d\btful cleavage may be deceptive4 ,if we are ju/ifi$ 9 reg>d+ ! introduction ( ?is volcanic mat]ial z hav+ necess>ily tak5 place aft] ! tilt+ ( ! /rata1 we may n unreasonably inf] fur!r t ! eruptions c\ld only h be5 effect$ at no great di/ance f ! surface4 ,b ! ,c>bonif]\s ,slate 9 :i* ^! agglom]ates lie is ! l[e/ memb] ( ! ,c>bonif]\s sy/em4 ,z !re is no kn[n uncon=mability ?r\gh\t ?is sy/em 9 ! s\? ( ,irel&1 ! :ole ( ! re/ ( ! pile ( ,c>bonif]\s /rata1 am\nt+ to a dep? ( sev]al ?\s& feet1 once probably ext5d$ ov] ?is region4 ,x mu/1 !re=e1 h be5 n only aft] ! plication1 b aft] ext5sive d5udation ( ! =mations t ! fissures 7 fill$ ) agglom]ate4 ,^! geological *anges no d\bt occupi$ a va/ p]iod ( "t4 ,:ile1 !re=e1 no positive evid5ce has yet be5 ga!r$ to fix ! age ( ^! volcanic eruptions ( ! s\?-we/ ( ,irel&1 x is tol]ably cle> t !y _c be assign$ to ! ,c>bonif]\s p]iod1 b mu/ belong to "s lat] volcanic epo*4 ,!y may be ( ,p]mian age1 p]haps ev5 z late z ! ,t]ti>y volcanic s]ies4 ,,book ,,vii ,,! ,,p]mian ,,volcanoes ,,*apt] ,,xxxi ,,! ,,p]mian ,,volcanoes ,,( ,,scotl& ,geographical ,*anges at ! ,close ( ! ,c>bonif]\s ,p]iod--,l&- & ,inl&-,seas ( ,p]mian "t--,g5]al ,*>act]i/ics & ,nature ( ! ,mat]ials erupt$--,/ructure ( ! sev]al ,volcanic ,di/ricts3 #a4 ,ayr%ire1 ,ni?sdale1 ,ann&ale2 #b4 ,bas9 ( ! ,fir? ( ,=?4 ,! close ( ! ,c>bonif]\s portion ( ! geological record 9 ,brita9 is m>k$ by ano!r ( ^? great gaps :i* s s]i\sly affect ! cont9uity ( geological hi/ory4 ,no transitional =mation1 su* z 9 o!r c\ntries m>ks ! gradation f ! ,c>bonif]\s into ! succe$+ p]iod1 has be5 def9itely recogniz$ 9 ?is c\ntry4 ,! highe/ ,c>bonif]\s /rata are "h sep>at$ f all y\ng] deposits by an uncon=mability1 indicat+ ! lapse ( va/ p]iods ( "t :]e(1 )9 ! ,briti% area1 no *ronicle has be5 pres]v$4 ,:5 we pass f ! ,c>bonif]\s sy/em to t :i* comes next to x 9 ord] ( "t1 we soon become s5sible t great *anges 9 geography1 betok5+ an imm5se int]val1 took place betwe5 !m4 ,! prolong$ subsid5ce dur+ :i* ! ,coal-measures 7 accumulat$1 n only c>ri$ d[n bel[ sea-level all ! tracts ov] :i* ! ,c>bonif]\s sy/em 0 deposit$1 b possibly subm]g$ ! la/ ( ! islets1 :i*1 l ^? ( ,*>nwood ,=e/1 _h surviv$ s _m geological *anges4 ,ev5tually1 h[ev]1 & aft] :at may h be5 a va/ p]iod ( quiesc5ce1 und]gr\nd movem5ts began anew1 & ! tracts ( ,coal-measures 7 unequally ridg$ up into l&4 ,! topography ?us produc$ appe>s to h result$ 9 ! =mation ( a s]ies ( inl& seas some:at l ^? ( ! ,old ,r$ ,s&/one1 b probably less 9 area & 9 dep?4 ,9 ^! bas9s ! wat] seems to h be5 on ! :ole unfav\rable to life1 = ! r$ s& & mud deposit$ 9 !m are g5]ally unfossilif]\s1 ?\gh1 :5 ! conditions became m suitable1 calc>e\s or dolomitic s$im5t accumulat$ on ! bottom1 to =m :at is n[ kn[n z ! ,magnesian ,lime/one1 & muddy s$im5t 0 deposit$ :i* is n[ ! ,m>l ,slate4 ,9 ^! less f]rug9\s /rata1 betok5+ a less noxi\s condition ( wat]1 v>i\s m>9e organisms are met )4#hg ,footnote #hg3 ,9 "s rec5t bor+s ar\nd ,h>tlepool ! ,magnesian ,lime/one has be5 f\nd to be int]/ratifi$ ) ?ick b&s ( gypsum & anhydrite1 & to be ov]la9 by m ?an #bej feet ( ! latt] sub/ance4 ,no?+ c\ld %[ m =cibly ! exce$+ly sal9e & insalubri\s "* ( ! ,p]mian lakes or inl& seas4 ,! vegetation ( ! l& surr\nd+ ^! bas9s 0 /ill ess5tially ,palozoic 9 "*4 ,x pres5t$ a g5]al resemblance to t ( ,c>bonif]\s "t1 b ) "s notable diff]5ces4 ,! jungles ( ,sigill>ia seem to h disappe>$1 :ile on ! o!r h&1 conif]s increas$ 9 numb] & v>iety4 ,! s$im5ts ( ! wat]-bas9s h h&$ d[n only a scanty remnant ( ! animal life ( ! "t4 ,along ! s&y %ores walk$ v>i\s amphibians :i* h left _! footpr9ts on ! s&4 ,a few g5]a ( ganoid fi%es h be5 f\nd 9 "s ( ! %ales1 & a comp>atively poor assemblage ( cr9oids & molluscs has be5 obta9$ f ! ,magnesian ,lime/one4 ,to ! geological p]iod di/+ui%$ by ^! geographical & biological *>act]s ! "n ( ,p]mian is assign$4 ,9 8 survey ( ! progress ( volcanic hi/ory 9 ! area ( ,brita91 ! geologi/ f9ds t ! long p]iod ( quiesc5ce indicat$ by ! deposition ( ! ,coal-measures1 & probably also by ! uncon=mability betwe5 ! ,coal-measures & ! ,p]mian =mations1 0 at l5g? t]m9at$ by a r5ew$ volcanic outbreak1 b on a s+ul>ly dim9i%$ scale & = a comp>atively brief p]iod ( "t4 ,:e!r1 _h ! ,p]mo-,c>bonif]\s /rata :i* connect ! ,coal-measures ) ! ,p]mian =mations on ! ,cont95t be5 f\nd 9 ?is c\ntry1 !y w\ld h fill$ up ! gap 9 ! geological record1 & w\ld h suppli$ any trace ( contemporane\s volcanic action1 _c ev5 be surmis$4 ,all t we "k is t1 aft] a va/ int]val1 & dur+ ! deposition ( ! breccias & r$ s&/ones :i* uncon=mably ov]lie ! ,coal-measures1 a few scatt]$ gr\ps ( little volcanoes appe>$ 9 ! area ( ! ,briti% ,isles4 ,x is un=tunate t 9 ^? di/ricts :]e ^! volcanic relics h be5 pres]v$1 ! /ratigraphical record is s+ul>ly imp]fect1 & t on ! ea/]n side ( ,engl&1 :]e ?is record is tol]ably complete1 !re are no int]calat$ volcanic rocks4 ,! latt] occur 9 tracts :]e ! /rata are almo/ :olly de/itute ( fossils1 & :]e !re=e no palontological evid5ce is available def9itely to fix ! geological age ( ! eruptions4 ,nev]!less !re is usually ample pro( t ! /rata 9 "q are mu* lat] ?an ! ,coal-measures1 :ile _! geological position & li?ological *>act]s l9k !m ) ! und\bt$ ,p]mian s]ies ( ! nor?-ea/ ( ,engl&4 ,!y may1 h[ev]1 belong to a comp>atively late "p ( ! ,p]mian p]iod1 if inde$ "s ( !m may n be ref]able to ! succe$+ or ,triassic p]iod4 ,! comp>atively feeble & %ort-liv$ volcanoes n[ to be describ$ are f\nd 9 two regions wide ap>t f ea* o!r4 ,! m important ( ^! lies 9 ! s\?-we/ & c5tre ( ,scotl&4 ,a second gr\p rose 9 ,devon%ire4 ,x is possible t a ?ird gr\p appe>$ betwe5 ^! two regions1 some:]e 9 ! midl&s4 ,! evid5ce = ! hi/ory ( ea* area w be giv5 9 a sep>ate section 9 ! foll[+ pages4 i4 ,,g5]al ,,*>act]i/ics--,,nature ,,( ,,mat]ials ,,erupt$ ,! *ief di/rict = ! display ( volcanic eruptions t may be assign$ to ! ,p]mian p]iod lies 9 ! c5tre ( ,ayr%ire & ! valleys ( ! ,ni? & ,annan4 ,b1 = reasons /at$ bel[1 ,i %all include )9 ! same volcanic prov9ce a l>ge "p ( ! ea/]n half ( ! bas9 ( ! ,fir? ( ,=? 7see ,map ,v474 ,un=tunately ! int]e/+ volcanic rocks n[ to be consid]$ h suff]$ sev]ely f ! effects ( d5udation4 ,!y h be5 entirely remov$ f wide tracts ov] :i* !y almo/ c]ta9ly once ext5d$4 ,b ?is enorm\s wa/e has n be5 :olly )\t comp5sations4 ,! lavas & tuffs eject$ at ! surface1 & once widely spread ov] x1 dur+ ! deposition ( ! r$ s&/ones1 h be5 r$uc$ to m]ely a few deta*$ fragm5ts4 ,b1 on ! o!r h&1 _! removal z a sup]ficial cov]+ has reveal$ ! v5ts ( dis*>ge to an ext5t unequall$ 9 any old] geological sy/em1 ev5 among ! puys ( ! ,c>bonif]\s p]iod4 ,! ,p]mian rocks1 escap+ ! effects ( ^? great e>?-movem5ts :i* dislocat$1 plicat$ & buri$ ! old] ,palozoic sy/ems ( deposits1 /ill rema9 = ! mo/ "p approximately horizontal or only g5tly incl9$4 ,!y h ?us be5 m liable to complete removal f wide tracts ( c\ntry ?an old] =mations :i* h be5 protect$ by hav+ l>ge portions ( _! mass c>ri$ d[n by ext5sive faults & syncl9al folds1 & by be+ buri$ "u lat] s$im5t>y accumulations4 ,we ought n1 !re=e1 to judge ( ! ext5t ( ! volcanic dis*>ges dur+ ,p]mian "t m]ely f ! small pat*es ( lava & tuff :i* h surviv$ 9 "o or two di/ricts1 b r f ! numb]1 size & di/ribution ( ! v5ts :i* ! "w ( d5udation has laid b>e4 ,! evid5ce = ! geological age ( ! volcanic s]ies n[ to be describ$ is less direct & obvi\s ?an mo/ ( t ) :i* ,i h be5 hi!rto deal+4 ,x consi/s ( two k9ds4 7a7 ,9 ! fir/ ( ^! comes ! s]ies ( lavas & tuffs j ref]r$ to z regul>ly int]/ratifi$ ) ! r$ s&/ones1 :i*1 on ! gr\nds giv5 9 ! next p>agraph1 x is agre$ to reg>d z ,p]mian4 7b7 ,connect$ ) ^! rocks are necks :i* obvi\sly s]v$ z v5ts = ! dis*>ge ( ! volcanic mat]ials4 ,!y pi]ce n only ! ,coal-measures1 b ev5 p>ts ( ! ov]ly+ b$d$ lavas4 ,s f> !re is n mu* room = diff]5ce ( op9ion2 b z we rec$e nor?w>d f ,ayr%ire & ,ni?sdale1 :]e ! int]calation ( ! volcanic s]ies 9 ! r$ s&/ones is well display$1 we ent] ext5sive tracts :]e ^! int]/ratifi$ rocks h disappe>$ & only ! necks rema94 ,all t c be positively ass]t$ reg>d+ ! age ( ^! necks is t !y mu/ be lat] ?an ! rocks :i* !y pi]ce4 ,b we may inf]5tially connect !m ) ! int]/ratifi$ lavas & tuffs by %[+ t !y c be foll[$ cont9u\sly outw>d f ! latt] z "o prolong$ gr\p1 hav+ ! same di/ribution1 /ructure & composition1 & t "h & !re !y rise ?r\gh ! v highe/ "p ( ! ,coal-measures4 ,x is by reason+ ( ?is k9d t ,i include1 z n improbably relics ( ,p]mian volcanoes1 a l>ge numb] ( v5ts scatt]$ ov] ! c5tre ( ,scotl&1 9 ! ,ea/ ( ,fife4 ,! r$ s&/ones among :i* ! volcanic s]ies is int]calat$ cov] sev]al deta*$ areas 9 ,ayr%ire & ,dumfries%ire4 ,li?ologically !y pres5t a close resemblance to ! ,p5ri? s&/one & breccias ( ,cumb]l&1 ! ,p]mian age ( :i* is g5]ally admitt$4 ,!y lie uncon=mably sometimes on ,l[] & ,upp] ,silurian rocks1 sometimes on ! l[] p>ts ( ! ,c>bonif]\s sy/em1 & sometimes on ! r$ s&/ones :i* =m ! highe/ subdivision ( t sy/em4 ,!y are ?us n only y\ng] ?an ! late/ ,c>bonif]\s /rata1 b are sep>at$ f !m by ! int]val repres5t$ by ! uncon=mability4 ,on ^! gr\nds !y are naturally look$ ^u z n old] ?an ! ,p]mian p]iod4 ,! only palontological evid5ce yet obta9$ f !m 9 ,scotl& is t furni%$ by ! well-kn[n footpr9ts ( ,ann&ale1 :i* indicate ! exi/5ce ( e>ly =ms ( amphibians or reptiles dur+ ! "t ( ! deposition ( ! r$ s&4 ,! precise zoological grade ( ^! animals1 h[ev]1 has nev] yet be5 det]m9$1 s t !y furni% little help t[>ds fix+ ! /ratigraphical position ( ! r$ rocks 9 :i* ! footpr9ts occur4 ,! /ratigraphical relations ( ! r$ s&/ones ( ,ayr%ire & ,ni?sdale 7 discuss$ by ,mur*ison1 ,b9ney & ,h>kness4#hh ,^! obs]v]s notic$ c]ta9 igne\s rocks ne> ! base ( ! s&/ones1 to :i*1 h[ev]1 z be+ suppos$ intrusive masses1 !y did n atta* importance4 ,!y reg>d$ ! volcanic tuffs ( ! same di/rict z ord9>y breccias1 :i* !y class$ ) ^? ( ,dumfries & ,cumb]l&1 ?\gh ,b9ney notic$ ! resemblance ( _! cem5t+ pa/e to t ( volcanic tuff1 & 9 ! end 0 d\btful :e!r to reg>d ! igne\s rocks z intrusive or int]/ratifi$4 ,footnote #hh3 ,see ,mur*ison's ,siluria1 #d? edit4 p4 #cca2 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 vii4 7#ahea71 p4 #afc1 note2 vol4 xii4 7#ahef71 p4 #bfg2 ,b9ney1 ibid4 vol4 xii4 7#ahef71 p4 #ach2 vol4 xviii4 7#ahfb71 p4 #dcg2 ,h>kness1 ibid4 vol4 xii4 7#ahef71 p4 #bfb4 ,9 ! ye> #ahfb1 on visit+ ! sections 9 ! ,riv] ,ayr1 ,i recogniz$ ! breccia z a true volcanic tuff4 ,dur+ ! foll[+ ye>s1 :ile mapp+ ! di/rict = ! ,geological ,survey1 ,i e/abli%$ ! exi/5ce ( a s]ies ( contemporane\s lavas & tuffs at ! base ( ! ,p]mian bas9 ( ,ayr%ire1 & ( num]\s necks m>k+ ! v5ts f :i* ^! mat]ials _h be5 erupt$4 ,an acc\nt ( ^! obs]vations 0 publi%$ 9 ! ye> #ahff4hi ,s9ce t "t ! progress ( ! ,survey has ext5d$ ! detail$ mapp+ into ,ni?sdale & ,ann&ale1 b )\t add+ any new facts ( importance to ! evid5ce furni%$ by ! ,ayr%ire tract4#ij ,footnote #hi3 ,geol4 ,mag4 = #ahff1 p4 #bdc2 & ,mur*ison's ,siluria1 #d? edit4 7#ahfg71 p4 #ccb4 ,footnote #ij3 ,! rocks are %[n 9 ,%eets #i1 #ad & #ae ( ! ,geological ,survey ( ,scotl&1 to :i*1 & _! accompany+ ,explanations1 ref]5ce is made4 ,! ,ayr%ire bas9 0 mapp$ by me1 ! necks 9 ! ,dalmell+ton gr\nd by ,mr4 ,james ,geikie1 ! ,ni?sdale area by ,mr4 ,r4 ,l4 ,jack1 ,mr4 ,h4 ,skae & myself4 ,! mat]ials erupt$ by ! ,scotti% ,p]mian volcanoes display a v limit$ petrographical range1 contra/+ /rongly 9 ?is respect ) ! ejections ( all ! previ\s geological p]iods4 ,!y consi/ ( lavas g5]ally m or less basic1 & (t5 mu* decay$ at ! surface2 & ( agglom]ates & tuffs d]iv$ f ! explosion ( ! same lavas4 ,! lavas are dull r$di% or purpli%-grey to br[n or almo/ black rocks2 sometimes compact & porphyritic1 b m usually /rongly amygdaloidal1 ! vesicles h be5 fill$ up ) calcite1 zeolites or o!r infiltration4 ,! porphyritic m9]als are 9 l>ge measure dull r$ e>?y pseudomorphs ( hmatite1 9 _m cases aft] oliv9e4 ,^! rocks h n yet be5 fully /udi$ 9 reg>d to _! composition & microscopic /ructure4 ,a few slides1 prep>$ f specim5s collect$ 9 ,ayr%ire & ,ni?sdale1 exam9$ by ,dr4 ,hat*1 7 f\nd to pres5t rem>kably basic *>act]s4 ,"o f ,mau*l9e ,hill is a picrite1 compos$ *iefly ( oliv9e & augite1 ) a little /rip$ felsp>4 ,o!rs f ! ,?ornhill bas9 9 ,dumfries%ire %[ an abs5ce ( oliv9e1 & sometimes ev5 ( augite4 ,! rock ( ,morton ,ca/le consi/s ( l>ge cry/als ( augite & num]\s gra9s ( magnetite 9 a felspa?ic gr\ndmass full ( magnetite4 ,ar\nd ,?ornhill are magnetite-felsp> rocks1 compos$ sometimes ( granul> magnetite ) int]/itial felsp>4 ,?r\gh\t all ! rocks !re has be5 a preval5t oxidation ( ! magnetite1 ) a consequ5t r$d5+ ( ! masses4 ,! pyrocla/ic mat]ials consi/ ( un/ratifi$ agglom]ates & tuffs1 g5]ally f\nd 9 necks1 & ( /ratifi$ tuffs1 :i* m or less m+l$ ) non-volcanic mat]ial1 especially r$ s&/one1 are int]calat$ among ! b$d$ lavas or ov]lie !m1 & pass upw>d into ! ord9>y ,p]mian r$ s&/ones4 ,! agglom]ates1 ?\gh sometimes co>se1 nev] conta9 su* l>ge blocks z are to be se5 among ! old] ,palozoic volcanic gr\ps4 ,_! composition be>s ref]5ce to t ( ! b$d$ lavas associat$ ) !m1 pieces ( ! v>i\s basalts1 &esites1 etc41 :i* con/itute ^! lavas be+ recognizable1 toge!r ) o!rs1 especially a gre51 f9ely-vesicul>1 palagonitic sub/ance1 :i* has n be5 detect$ among ! %eets ( lava4 ,9 g5]al ! agglom]ates conta9 m matrix ?an blocks1 & pass readily into gravelly tuffs4 ,a s]ies ( specim5s collect$ by me f necks :i* pi]ce ! ,dalmell+ton coal-field has be5 slic$ & exam9$ "u ! microscope by ,mr4 ,watts1 :o f9ds x to consi/ ( basic tuffs1 9 :i* ! lapilli include v>i\s types ( oliv9e-basalt1 sometimes glassy1 sometimes palagonitic1 & occasionally holocry/all9e1 also pieces ( grit1 %ale & lime/one4 ,9 "o case a cr9oid jo9t deta*$ f its matrix 0 notic$4 ,a specim5 f ,patna ,hill consi/s ( a cle> irregul>ly crack$ aggregate ( c>bonates & qu>tz ) hornbl5de1 & its /ructure rem9ds "o ( t ( oliv9e4 ,! hornbl5de is 9 small irregul> pat*es surr\nd$ by ! cle> m9]al1 & is probably a replacem5t ( a pyrox5e1 p]haps diallage4 ,if ?is /one 0 once an oliv9e nodule1 ! agglom]ate might 9 ?is respect be comp>$ ) "s ( ! tuffs ( ! ,eifel s well kn[n = _! lumps ( oliv9e4 ,! /ratifi$ tuffs are g5]ally m or less gravelly deposits1 compos$ ( lapilli v>y+ 9 size f m]e gra9s up to pea-l fragm5ts1 b ) num]\s l>g] /ones & occasional blocks ( /ill great] dim5sions4 ,!y (t5 pass into a t\gh dull compact mud/one4 ,9 col\r !y are gre5i% or r$di%4 ,!y h be5 l>gely d]iv$ f ! explosion ( lavas g5]ally simil> to ^? ( :i* fragm5ts occur 9 ! agglom]ates4 ,!y (t5 conta9 non-volcanic detritus1 d]iv$ f ! bl[+ up ( ! rocks ?r\gh :i* ! v5ts 7 op5$4 ,occasionally !y include also v>i\s m9]als su* z pyrope1 black mica1 sanid9e1 augite1 & o!rs :i* appe> to h be5 eject$ z loose & (t5 brok5 cry/als4 ,?is "* is m fully describ$ 9 reg>d to its occurr5ce among ! necks ( ! ea/ "p ( ,fife4 ,! intrusive rocks1 probably ref]able to ! same volcanic p]iod1 consi/ *iefly ( dol]ites & basalts :i* occur z dykes1 sills & bosses1 & are m p>ticul>ly develop$ 9 ! s\?-we/ ( ,ayr%ire4 ii4 ,,geological ,,/ructure ,,( ,,! ,,volcanic ,,di/ricts #a4 ,ayr%ire1 ,ni?sdale & ,ann&ale 7#a7 ,int]/ratifi$ ,lavas & ,tuffs4--,x w be conv5i5t to consid] fir/ ! volcanic *ronicle z x has be5 pres]v$ 9 ! s\?-we/ & s\? ( ,scotl&1 :]e ! exi/5ce ( ,p]mian volcanoes 9 ,brita9 0 fir/ recogniz$4 ,! volcanic rocks 9 ! middle ( ! ,ayr%ire coal-field rise f "u a c5tral bas9 ( r$ s&/one1 :i* !y completely enclose4 ,_! outcrop at ! surface v>ies up to ab\t a mile or r m 9 bread?1 & =ms a pe>-%ap$ r+1 measur+ ab\t n9e miles across at its greate/ wid? 7,map ,v474#ia ,footnote #ia3 ,mr4 ,gunn has rec5tly detect$ among ! newe/ r$ s&/ones ( ,arran a small pat* ( volcanic rocks :i* may be ( ?is age4 ,mr4 ,a4 ,maccono*ie has also f\nd :at may be traces ( a simil> volcanic b& bel[ ! ,p]mian s&/ones ( ,lo* ,ryan1 9 ,wigton%ire4 ,?is volcanic r+ runs z a tract ( high] gr\nd encircl+ ! holl[ 9 :i* ! ,p]mian r$ s&/ones lie1 & =m+ a m>k$ *a9 ( heights above ! ,c>bonif]\s c\ntry ar\nd4 ,x is built up ( a succession ( %eets ( diff]5t lavas1 ) occasional p>t+s ( tuff or volcanic breccia1 :i* pres5t _! esc>pm5ts t[>ds ! coal-field outside1 & dip g5tly into ! bas9 "u ! inn] tr\gh ( brick-r$ s&/ones4 ,good sections ( ! rocks are expos$ 9 ! rav9es ( ! ,riv] ,ayr1 p>ticul>ly at ,ballo*myle1 9 ! ,dippol ,burn ne> ,au*9leck ,h\se1 & 9 ! railway cutt+ ne> ,mossgiel4 ,t ^! are true lava-fl[s1 & n intrusive sills1 is suffici5tly obvi\s f _! g5]al outw>d li?ological aspect1 "s ( !m be+ ess5tially %eets ( slag & scori4 ,_! upp] surfaces may be f\nd ) a f9e indurat$ r$ s& wrapp+ r\nd ! scori=m lumps & protub]ances1 & fill+ 9 ! r5ts & int]spaces1 z 9 ! case ( ! ,old ,r$ ,s&/one lavas already ref]r$ to4 ,z an example ( ^! *>act]i/ics1 ,i may cite ! section repres5t$ 9 ,fig4 #bjj4 ,at ! bottom lies a r$ highly f]rug9\s & co>sely amygdaloidal basalt 7a74 ,ov] x comes a volcanic conglom]ate ?ree feet ?ick1 made up ( balls ( vesicul> lava l t bel[1 wrapp$ 9 a brick-r$ s&y matrix 7b74 ,l5ticul> b&s ( s&/one )\t blocks occur 9 ! conglom]ate1 & o!rs lie 9 holl[s ( its upp] surface 7c74 ,?is int]calation ( detrital mat]ial is foll[$ by ano!r basic lava 7d71 ab\t six feet ?ick1 highly amygdaloidal 9 its l[] & upp] p>ts1 m compact 9 ! c5tre4 ,! amygdales & jo9ts are l>gely fill$ ) calcite4 ,! slaggy bottom has caught up & n[ encloses "s ( ! r$ s& ( ! deposit bel[4 ,ano!r lava f ?ree to six feet ?ick next appe>s 7e71 :i* is rem>kable = its slaggy /ructure1 & is s decompos$ t x crumbles away4 ,l ! o!rs x is dull-r$ & f]rug9\s & full ( calcite4 ,x mu/ h be5 at ! "t ( its outfl[ a %eet ( r\gh slag t crack$ into op5 fissures4 ,t x 0 p\r$ out "u wat] is aga9 %[n 9 ! same int]e/+ way j ref]r$ to1 by ! r$ s& :i* has be5 wa%$ into ! int]spaces betwe5 ! cl9k]s & has fill$ up ! fissures1 9 :i* x is /ratifi$ horizontally betwe5 ! walls4 ,above ?is b&1 & p]haps pass+ into x z its slaggy base1 lies ano!r m compact lava 7f7 l ! l[] %eets4 ,illu/ration3 ,fig4 #aii4--;,g5]al section across ! ,p]mian bas9 ( ,ayr%ire4 #a4 ,highe/ gr\p ( ! ,coal-measures2 #b4 ,volcanic tuffs & a%y brick-r$ s&/ones2 #c4 ,lavas ) int]/ratifi$ tuffs & brick-r$ s&/ones2 #d4 ,brick-r$ ,p]mian s&/ones2 #e1 #e4 ,necks ( volcanic agglom]ate2 #f4 ,boss ( dol]ite4 ,?r\gh\t ! s]ies ( lavas1 z indicat$ 9 ! =ego+ section1 traces ( ! pauses t elaps$ betwe5 ! sep>ate outfl[s may be se5 9 ! =m ei!r ( lay]s ( r$ s&/one or ( tuff & volcanic breccia4 ,"h & !re1 "u ! plat=m ( b$d$ lavas1 ! brick-r$ s&/one is full ( fragm5ts ( slag & f9e volcanic du/4 ,b ! mo/ abundant accumulation ( su* detritus is to be se5 at ! top ( ! volcanic s]ies1 :]e x conta9s ! records ( ! clos+ phases ( eruption4 ,?ick b$s ( tuff & volcanic breccia occur !re1 int]leav$ ) seams ( r$ s&/one1 l ! *ief mass ( t rock1 into :i* !y gradually pass upw>d4 ,yet1 ev5 among ! s&/ones above ! ma9 body ( tuff1 occasional ne/s ( volcanic lapilli1 & ev5 l>ge bomb-l lumps ( slag1 po9t to int]mitt5t explosions be=e ! volcanoes became f9ally ext9ct & 7 buri$ "u ! ?ick mass ( r$ ,p]mian s&/one4 ,illu/ration3 ,fig4 #bjj4--,section ( lavas ea/ side ( ,mau*l9e ,hill4 ,illu/ration3 ,fig4 #bja4--,section ( ! top ( ! volcanic s]ies ne> ,ea/side ,cottage1 ,c>ron ,wat]1 ,ni?sdale4 ,!re is good reason to believe t bo? ! volcanic %eets & ! r$ s&/ones ov]ly+ !m1 in/ead ( be+ re/rict$ to an area ( only ab\t #cj squ>e miles1 once /ret*$ ov] ! l[l&s ( ,ayr%ire2 & n only s1 b t !y ran d[n ,ni?sdale1 & ext5d$ into sev]al ( its tribut>y valleys1 if inde$1 !y 7 n cont9u\s across into ! valley ( ! ,annan4#ib ,traces ( ! lavas & tuffs are to be f\nd at int]vals ov] ! area "h indicat$4 ,! mo/ important display ( !m1 next to _! developm5t 9 ,ayr%ire1 occurs 9 ! vale ( ! ,ni? at ,?ornhill1 :5ce !y ext5d cont9u\sly up ! floor ( ! ,c>ron ,valley = six miles4 ,!y =m "h1 z 9 ,ayr%ire1 a b& at ! base ( ! brick-r$ s&/ones1 & consi/ ma9ly ( b$d$ lavas ) ! basic *>act]s above ref]r$ to4 ,^! lavas1 h[ev]1 are foll[$ "h by a mu* ?ick] developm5t ( fragm5tal volcanic mat]ials4 ,abundant volcanic detritus is diffus$ ?r\gh ! ov]ly+ s&/ones1 sometimes z a gravelly int]mixture1 sometimes 9 l>ge slaggy blocks or bombs1 & sometimes 9 int]calat$ lay]s ( tuff1 :ile an occasional %eet ( "o ( ! dull r$ lavas may also be detect$4 ,! f9al dy+-out ( ! volcanic en]gy 9 a s]ies ( int]mitt5t explosions1 :ile ! ord9>y r$ s&y s$im5t 0 accumulat+1 is "h also admirably *ronicl$4 ,z an illu/ration ( ^! features ! accompany+ section is giv5 7,fig4 #bja74 ,! la/ ( ! lavas 7a7 pres5ts an unev5 surface aga9/ :i* ! v>i\s k9ds ( detritus h be5 laid d[n4 ,fir/ comes a co>se volcanic breccia 7b7 made up ( angul> & subangul> blocks ( diff]5t lavas imb$d$ 9 a matrix ( r$ a%y s&4 ,?is deposit is succe$$ by a b& ( dull r$ tuface\s s&/one1 evid5tly =m$ ( ord9>y r$ s&y s$im5t1 into :i* a quantity ( volcanic du/ & lapilli fell at ! "t ( its accumulation4 ,"s ( ! eject$ blocks :i* lie inclos$ 9 ! f9] s$im5t are upw>ds ( a foot 9 l5g?4 ,a m vigor\s dis*>ge ( fragm5tal mat]ial is %[n by ! next b$ 7d71 :i* consi/s ( a co>se nodul> tuff1 m+l$ ) a little r$ s&/one & cr[d$ ) blocks ( ! usual lavas4 ,beyond ! locality ( ?is section ^! tuffs are f\nd to pass up ins5sibly into ! ord9>y ,p]mian s&/one4 ,footnote #ib3 ,see ,memoirs ( ,geol4 ,surv4 ,scotl&1 ,%eet #ae 7#ahga71 p4 #ce2 ,%eet #i 7#ahgg71 p4 #ca4 ,illu/ration3 ,fig4 #bjb4--,section ( two outli]s ( ! ,p]mian volcanic s]ies at ! foot ( ,w9dyhill ,burn1 ,wat] ( ,ae1 ,dumfries%ire4 ,b we c detect ! edges ( yet m di/ant /reams ( lava em]g+ f "u ! r$ s&/ones & breccias to ! ea/ ( ! ,ni?4 ,on ! f>!r side ( ! ,silurian ridge t =ms ! ea/]n b\nd>y ( ! ,ni? valley1 above :i* x rises "s #gjj or #hjj feet1 !re is pres]v$ at ! bottom ( ! valley ( ! ,capel ,wat]1 :i* fl[s into ,ann&ale1 ano!r small outli] ( a simil> volcanic b&4 ,?ree miles to ! s\?-ea/ ( x two little fragm5ts ( ! volcanic gr\p lie on ! sides ( a small tribut>y ( ! ,wat] ( ,ae4 ,s9ce ^! may s]ve z a good illu/ration ( ! ext5t to :i* d5udation has r$uc$ ! area ( ! ,p]mian volcanic s]ies1 a section ( ! locality is "h giv5 7,fig4 #bjb74 ,! g5]al f\ndation rocks ( ! c\ntry are ! ,silurian greywackes & %ales 9 highly incl9$ & contort$ positions 7a74 ,ea* outli] has1 z its basem5t mat]ial1 a volcanic breccia 7bb7 9 :i*1 toge!r ) ! usual lava-fragm5ts1 are m+l$ pieces ( ! surr\nd+ ,silurian /rata4 ,9 ! small] outli] ly+ to ! nor?-ea/1 ?is detrital lay] is only ab\t "o foot ?ick4 ,x is ov]la9 by a slaggy amygdaloid ( ! usual "* 7cc71 :i* 9 ! l[] outli] is cov]$ ) b\ld] clay 7d74 ,!re c be little d\bt t ^! deta*$ fragm5ts 7 once unit$ 9 a cont9u\s %eet ( lava :i* fill$ ! valley ( ! ,wat] ( ,ae & t ( its tribut>y4 ,t ! lava /ret*$ d[n ! ,ae valley = "s di/ance is prov$ by ! occurr5ce ( ano!r outli] ( x two miles bel[4 ,b !re is /ill additional evid5ce = ! wide ext5sion ( ^! volcanic %eets4 ,x appe>s to be c]ta9 t !y /ret* f> to ! ea/w>d1 "u ! ,p]mian s&/ones ( ! ,lo*mab5 bas9 ( ,ann&ale1 = breccias l>gely made up ( pieces ( ! b$d$ lavas are f\nd close to ! nor!rn edge ( ! bas9 on ! we/ side ( ! ,riv] ,annan4 ,to ?is rem>kable adh]5ce ( ! lavas & tuffs to ! bottom ( ! ,p]mian valleys ,i %all aft]w>ds m specially ref]4 ,! ?ickness ( ! :ole volcanic gr\p _c be v accurately det]m9$4 ,x rea*es a maximum 9 ! ,ayr%ire bas91 :]e1 at its greate/1 x probably does n exce$ #ejj feet1 b is g5]ally mu* less2 :ile 9 ! ,ni?sdale & ,ann&ale gr\nd ! deta*$ & mu* d5ud$ areas %[ a /ill ?9n] developm5t4 ,illu/ration3 ,fig4 #bjc4--,! ,gre5 ,hill1 ,wat]side1 ,dalmell+ton1 f ! s\?2 a tuff-neck ( ,p]mian age4 7#b7 ,v5ts4--,"o ( ! mo/ int]e/+ features 9 ?is s\?-we/]n di/rict ( ,scotl& is ! admirable way 9 :i* ! volcanic v5ts ( ,p]mian "t h be5 pres]v$4 ,_! connection ) ! lavas & tuffs c !re be s cle>ly trac$ t !y s]ve z a guide 9 ! int]pretation ( o!r gr\ps ( v5ts 9 di/ricts :]e no su* connection n[ rema9s4 ,9 ,ayr%ire1 ! l[] "p ( ! ,p]mian volcanic b& is pi]c$ by sev]al small necks ( agglom]ate4 ,!re _c1 ,i ?9k1 be any d\bt t ^! necks m>k ! positions ( "s ( ! v5ts f :i* ! lat] eruptions took place4 ,imm$iately beyond !m necks ( precisely simil> "* rise ?r\gh ! upp] division ( ! ,coal-measures4 ,!re c be z little hesitation 9 plac+ ^! also among ! ,p]mian v5ts4 ,& ?us /ep by /ep we are l$ away f ! c5tral lavas1 ?r\gh gr\ps ( necks pres]v+ /ill ! same features1 ext]nal & int]nal1 & ris+ indiff]5tly ?r\gh rocks ( any geological age f ! ,coal-measures backw>d4 ,?us1 al?\gh if we began ! inve/igation at ! out] limits ( ! *a9 ( necks1 we might well hesitate z to _! age1 yet1 :5 we c fix _! geological position 9 "o c5tral area1 we are1 ,i ?9k1 ju/ifi$ 9 class+1 z p>ts ( "o geologically syn*ron\s s]ies1 all ! connect$ gr\ps t reta9 ! same g5]al *>act]i/ics4 ,x is to d5udation t we owe _! hav+ be5 laid b>e to view2 b at ! same "t1 d5udation has remov$ ! %eet ( eject$ mat]ials :i* may h orig9ally connect$ mo/ ( ^! v5ts toge!r4 ,9 ?is reg>d1 x is mo/ in/ructive to foll[ ! v5ts s\?-ea/w>ds f ! ,ayr%ire bas9 into ,ni?sdale = a di/ance ( "s eighte5 miles4 ,if we trac$ !m d[n t valley to ,sanquh>1 )\t meet+ ) any ve/ige ( sup]ficial outfl[s to m>k _! /ratigraphical position1 we might possibly hesitate :e!r ! age ( ^? :i* are s f> remov$ f ! evid5ce t w\ld fix x %\ld n be left 9 d\bt4 ,b if we cont9u$ our trav]se only a few hundr$ y>ds f>!r1 we %\ld f9d "s fragm5t>y outli]s ( ! ,p]mian lavas capp+ ! ,upp] ,coal-measures2 & if we m]ely cross$ f ! ,ni? into ! tribut>y valley ( ! ,c>ron ,wat]1 we %\ld see pres]v$ 9 t deep holl[ a great s]ies ( ,p]mian lavas1 tuffs & agglom]ates4 ,x is only by a happy accid5t t "h & !re ^! sup]ficial volcanic accumulations h n be5 swept away4 ,!re 0 probably nev] any great ?ickness ( !m1 b !y no d\bt cov]$ mo/1 if n all1 ( ! di/rict )9 :i* ! v5ts are f\nd4 ,! ,p]mian necks are1 on ! :ole1 small] ?an ^? ( ! ,c>bonif]\s p]iod4 ,! l>ge/ ( !m 9 ! ,ayr%ire & ,ni?sdale region d n exce$ #djjj feet 9 longe/ diamet]2 ! great majority are mu* less 9 size1 :ile ! smalle/ measure #bj y>ds1 or ev5 less4 ,^? ( ,fife1 to be aft]w>ds describ$1 exhibit a wid] range ( dim5sions1 & h ! special advantage ( be+ expos$ 9 plan along ! %ore4 ,illu/ration3 ,fig4 #bjd4--,patna ,hill f ! ,doon ,bridge1 ,ayr%ire2 a tuff-neck ( ,p]mian age4 ,^! necks1 f _! numb] & %apes1 =m a m>k$ feature 9 ! sc5]y4 ,!y g5]ally rise z prom95t1 r\nd$1 dome-%ap$1 or conical hills1 :i*1 z ! rock comes close to ! surface1 rema9 p]man5tly cov]$ ) grass 7,figs4 #bjc & #bjd74 ,su* smoo? gre5 puys are conspicu\s 9 ! he>t ( ,ayr%ire1 & likewise fur!r s\? 9 ! ,dalmell+ton coal-field1 :]e "s ( !m are locally kn[n z ,gre5 ,hill1 f _! v]dant slopes 9 contra/ to ! br[n] vegetation ( ! poor] soil ar\nd !m 7,fig4 #bjc74 ,z 9 ^? ( old] geological p]iods1 ! necks ( ?is s]ies are1 = ! mo/ "p1 irregul>ly circul> or oval 9 gr\nd-plan1 b sometimes1 l ^? ( ! ,c>bonif]\s sy/em1 !y take curi\s oblong %apes1 & occasionally look z if two v5ts _h coalesc$ 7,fig4 #bje74 ,"h & !re also ! mat]ial ( ! v5ts has consolidat$ betwe5 ! walls ( a fissure or ! planes ( ! /rata1 s z to appe> r z a dyke ?an z a neck4 ,desc5d+1 z usual1 v]tically ?r\gh ! rocks :i* !y pi]ce1 ! necks h ! =m ( v]tical columns ( volcanic mat]ial1 end+ at ! surface 9 grassy r\nd$ hillocks or hills4 ,9 almo/ all cases1 ! necks ( ! ,ayr%ire region consi/ ( a gravelly tuff or agglom]ate1 r$di% or gre5i% 9 col\r1 made up ( blocks ( su* lavas z =m ! b$d$ %eets1 toge!r ) fragm5ts ( ! /ratifi$ rocks ?r\gh :i* ! *imneys h be5 bl[n out4 ,?us1 9 "s ( ! necks1 pieces ( black %ale are abundant1 z at ,patna4 ,9 o!r cases1 !re are pro(s ( ! d]ivation ( ! /ones f mu* great] dep?s1 z 9 ! ,gre5 ,hill ( ,wat]side1 :]e fragm5ts ( f9e greywacke are n infrequ5t1 probably d]iv$ f ! ,silurian =mations :i* lie deep b5ea? ! ,c>bonif]\s & ,old ,r$ ,s&/one s]ies4 ,! fragm5t>y mat]ial ( ! necks is g5]ally un/ratifi$1 b a rude /ratification may sometimes be notic$1 ! dip be+ irregul>ly inw>d at high angles t[>ds ! middle ( ! v5t4 ,?is /ructure1 be/ se5 9 ! v5ts ( ! ,fife coa/1 z w be %[n 9 ! sequel1 may be detect$ 9 "s ( ! necks ( ! ,dalmell+ton di/rict4 ,illu/ration3 ,fig4 #bje4--;,gr\nd plans ( ,p]mian volcanic v5ts f ! ,ayr%ire ,coal-field4 ,on ! scale ( six in*es to a mile4 #a4 ,neck half a mile nor?-we/ f ,dalmell+ton2 #b4 ,neck at ,au*5gee1 f\r miles nor?-ea/ f ,patna2 #c4 ,neck at head ( ,drumb[ie ,burn1 five & a half miles due nor? f ,dalmell+ton2 #d4 ,patna ,hill1 #hec feet above sea-level 7= outl9e ( ?is hill see ! prec$+ ,fig472 #e4 ,neck on ,ki]s ,hill 7#ajje feet above ! sea71 two miles s\? f ,patna1 ) lava adh]+ to "p ( ! wall4 ,occasionally "s =m ( molt5 rock has ris5 9 ! funnel1 & has p>tially or :olly remov$ or conceal$ ! agglom]ate4 ,?is feature is especially noticeable among ! necks t pi]ce ! ,dalmell+ton coal-field4 ,portions ( basic lavas trav]se ! agglom]ate or int]v5e betwe5 x & ! surr\nd+ /rata4 ,^! h probably 9 mo/ cases be5 =c$ up ! wall ( ! funnel1 :ile "h & !re sills run outw>d f ! necks into ! surr\nd+ ,coal-measures4 ,sometimes a ?9 %eet ( lava1 adh]+ to ! wall ( a funnel1 may be ! remnant ( a mass ( rock t once fill$ up ! orifice4 ,9 "o ( ! necks ( ! ,muirkirk ,coal-field1 :i* 0 pi]c$ by a m9e driv5 ?r\gh x f side to side1 f+]s & %eets ( :ite trap1 or highly alt]$ basalt1 7 f\nd to run out f ! neck into ! surr\nd+ /rata4#ic ,d>k heavy basalt1 or "s /ill m basic rock1 has "h & !re fill$ up a v5t4 ,z s _m ( ! necks rise ?r\gh ! coal-fields1 opportunities are af=d$ ( /udy+ ! effects ( volcanic action ^u ! coal-seams1 :i* = "s di/ance f !m h be5 de/roy$4 ,footnote #ic3 ,explanation ( ,%eet #bc1 ,geol4 ,surv4 ,scotl&1 p4 #ci4 ,ano!r feature1 :i* c be recogniz$ f ! in=mation obta9$ 9 m9+ op]ations1 is t1 9 ! great majority ( in/ances1 no connection is traceable betwe5 ! positions ( ! v5ts & su* l9es ( dislocation z c be detect$ at ! surface or 9 ! und]gr\nd work+s4 ,"s v5ts1 inde$1 h evid5tly _h _! positions det]m9$ by l9es ( fault1 z1 = in/ance1 t ( ! ,gre5 ,hill bel[ ,dalmell+ton4 ,yet 9 ! same neighb\rhood a numb] ( o!r examples may be f\nd :]e ! volcanic funnels seem to h avoid$ faults1 ?\gh ^! exi/ close to !m4 ,9 ?is s\?-we/]n di/rict ( ,scotl& upw>ds ( sixty di/9ct v5ts h be5 mapp$ 9 ! c\rse ( ! ,geological ,survey4 ,!y run f ! nor? ( ,ayr%ire to ! foot ( ! ,s\!rn ,upl&s1 & desc5d = "s di/ance ! vale ( ! ,ni?4 ,! area ov] :i* !y are di/ribut$ measures r\ghly ab\t =ty miles f nor?-we/ to s\?-ea/1 & at its greate/ bread? tw5ty miles f s\?-we/ to nor?-ea/4 ,)9 ?is tract ! v5ts are scatt]$ some:at sporadically 9 gr\ps1 sometimes numb]+ tw5ty necks 9 a space ( sixte5 squ>e miles1 z 9 ! rem>kable di/rict ( ,dalmell+ton4 ,9 consid]+ _! di/ribution we _c b be impress$ by ! /rik+ mann] 9 :i* ^! necks keep to ! valleys & l[ gr\nds4 ,i h already allud$ to ?is *>act]i/ic1 z %[n by ! volcanoes ( ! ,old ,r$ ,s&/one & ,c>bonif]\s p]iods4 ,b x is display$ by ! ,p]mian volcanoes 9 a /ill m a/oni%+ way4 ,beg9n+ at ! nor!rn end ( ! long *a9 ( necks 9 ! ,we/ ( ,scotl&1 we f9d a r[ ( !m on ! pla9s front+ ! volcanic plateau ( ! ,ardrossan1 ,dunlop & ,/ew>ton ,hills4 ,!nce we may foll[ !m1 z s+le individuals or 9 small gr\ps1 across ! broad l[l& ( ,ayr%ire1 s\?w>d to ! v base ( ! great *a9 ( ! ,s\!rn ,upl&s4 ,!re1 a clu/] ( "s two doz5 ( !m may be se5 ris+ out ( ! ,c>bonif]\s rocks on ! l[ gr\nds1 b !y abruptly cease close to ! base ( ! hills2 n "o has be5 detect$ on ! adjac5t ,silurian heights4 ,moreov]1 if we turn into ! valleys t lead away f ! great ,ayr%ire pla9 to ! int]ior1 we f9d necks ( ! same "* 9 ^! depressions4 ,!y asc5d ! valley ( ,muirkirk1 & may be met ) ev5 at its v head1 ne> ! base ( ! ,hag%aw ,hills4 ,aga91 on ! floor ( ! rem>kable transv]se valley tr5*$ by ! ,ni? across ! ,s\!rn ,upl&s1 ,p]mian necks pi]ce ! ,coal-measures1 :ile ! outly+ fragm5ts ( b$d$ lava %[ t ^! v5ts flood$ ! bottom ( t valley ) molt5 rock4 ,turn+ out ( ,ni?sdale into ! long n>r[ gl5 ( ! ,c>ron ,wat]1 we obs]ve its floor & sides to be cov]$ ) ! %eets ( lava & tuff already notic$4 ,& s travell+ onw>d f ! vale ( ! ,ni? into t ( ! ,capel ,wat]1 !nce into ! ,wat] ( ,ae & across into ! great /ra? ( ,ann&ale1 we may detect1 if n actual v5ts1 at lea/ ! b$s ( lava & lay]s ( volcanic detritus t 7 eject$ f !m4 ,all along ^! valleys1 :i* 7 already valleys 9 ,c>bonif]\s "t1 traces ( ! volcanic activity ( ?is epo* may be detect$4 ,b1 s f> z ,i am aw>e1 9 n a s+le case has any v5t be5 obs]v$ to h be5 op5$ on ! high surr\nd+ ridges4 ,!re has obvi\sly be5 a det]m9+ cause :y ! volcanic orifices %\ld h kept to ! pla9s & ! ma9 valleys ) _! tribut>ies1 & %\ld h avoid$ ! hills :i* rise n[ to heights ( #ejj to #ajjj feet or m above ! bottoms ( ! valleys t trav]se !m4 ,x might be said t ! valleys foll[ l9es ( fracture1 & t ! v5ts h be5 op5$ along ^! l9es4 ,b my colleagues 9 ! ,geological ,survey1 z well z myself1 h fail$1 9 mo/ cases1 to f9d any evid5ce ( su* dislocations among ! rocks t =m ! surface ( ! c\ntry1 :ile x is sometimes possible to prove t !y really d n exi/ !re4 ,?\gh only a few scatt]$ pat*es ( ! ,p]mian b$d$ lavas & tuffs h be5 pres]v$1 en\gh is left to indicate t ! v5ts 7 active only 9 ! e>ly "p ( ! p]iod repres5t$ by ! ,scotti% ,p]mian r$ s&/ones1 = x is entirely 9 ! l[] "p ( ^! /rata t volcanic rocks occur4 ,! eruptions gradually ceas$1 & ! %eets ( eject$ mat]ial1 probably also ! volcanic cones1 7 buri$ "u at lea/ sev]al hundr$ feet ( r$ s&/one4 ,:e!r or n any portion ( ! erupt$ mat]ial 0 = a "t built up above ! level ( ! wat]1 !re seems to be no "q t ! v5ts 71 on ! :ole1 subaque\s4 ,illu/ration3 ,fig4 #bjf4--,section ( sills trav]s+ ! ,p]mian volcanic s]ies4 ,riv] ,ayr1 ,ballo*myle4 a1 ,coal-measures2 b b1 ,basic lavas2 c c1 ,brick-r$ s&/ones ) tuff2 d1 ,r$ tuff & volcanic breccia2 e e1 ,dol]ite sills4 #c4 ,sills4--,! ph5om5a ( sills & dykes are less cle>ly develop$ among ! ,p]mian volcanic rocks ( ! ,ayr%ire bas9 ?an among ^? ( old] =mations4 ,9 ! section expos$ 9 ! c\rse ( ! ,riv] ,ayr at ,h[=d ,bridge1 a co>sely cry/all9e dol]ite :i* ext5ds = ne>ly #cjj y>ds up ! /ream1 cuts ! ,p]mian lavas1 ( :i* x encloses pat*es z well z pieces ( s&/one4 ,at ! contact1 ! rock becomes f9e-gra9$ 7,fig4 #bjf74 ,?r\gh ! co>sely cry/all9e mat]ial run long p>allel segregation ve9s ( a pal]1 m acid sub/ance1 z among ! ,c>bonif]\s sills4 ,simil> rocks are well se5 9 ! ,dippol ,burn ne> ,au*9leck ,h\se4 ,pass+ outw>d into ! ,coal-measures1 we enc\nt] a mu* l>g] display ( simil> intrusive %eets4 ,! be/ di/rict = ! /udy ( ^! sills lies ar\nd ,dalmell+ton4 ,! ,coal-measures are !re trav]s$ by _m intrusions1 :i* h produc$ great de/ruction among ! coal-seams4 ,"s ( ! rocks are extremely basic1 includ+ a beautiful picrite l t ( ,in*colm 7,le?am ,hill1 ne> ,wat]side74 ,! age ( ^! sills mu/ be lat] ?an ! ,coal-measures into :i* !y h be5 inject$4 ,"s ( !m are obvi\sly connect$ ) ! agglom]ate-necks1 & ! :ole or ! great] numb] %\ld ?us probably be assign$ to ! ,p]mian p]iod4#id ,! ph5om5a ( intrusion pres5t$ by ^! rocks reproduce ! appe>ances already describ$ 9 connection ) ! basic intrusive %eets ( ,c>bonif]\s age4 ,footnote #id3 ,explanation ( ,%eet #ad1 ,geol4 ,surv4 ,scotl&1 p4 #bb4 #b4 ,bas9 ( ! ,fir? ( ,=? ,! o!r di/rict ( ,s\!rn ,scotl&1 :]e traces ( volcanic action lat] 9 age ?an ! ,coal-measures may be obs]v$1 lies 9 ! bas9 ( ! ,fir? ( ,=? 7,map ,v474 ,!y include no b$d$ lavas1 & only at "o locality d any relics ( a cov]+ ( /ratifi$ tuffs ov]spread ! ,c>bonif]\s =mations4 ,! evid5ce = ! old volcanoes consi/s almo/ entirely ( necks ( tuff1 :i* m>k ! position ( v5ts ( eruption4 7#a7 ,v5ts4--,on ! s\? side ( ! e/u>y ( ! ,=? !re is only "o neck :i* may be plausibly plac$ 9 ?is s]ies4 ,x =ms ! upp] "p ( ,ar?ur ,seat1 at ,ed9burgh4 ,?is hill has already be5 cit$ z consi/+ ( two di/9ct portions4 ,! l[]1 built up ( b$d$ tuffs1 basalts & &esites1 =ms "p ( ! ,midlo?ian volcanic plateau ( ,c>bonif]\s "t4 ,! v5t f :i* ^! mat]ials 7 eject$ mu/ lie at "s little di/ance1 & its site has n be5 c]ta9ly asc]ta9$4 ,! upp] "p ( ! hill is =m$ ( a di/9ct gr\p ( rocks :i* has n[ to be describ$4 ,! geological /ructure ( ,ar?ur ,seat has long be5 well kn[n4 ,x s]v$ z a !me = discussion 9 ! ,neptuni/ & ,plutoni/ controv]sy1 & 0 (t5 ref]r$ to 9 ! v>i\s m9]alogical or geogno/ical writ+s ( ! "t4 ,! fir/ ?or\gh exam9ation ( x z a relic ( anci5t volcanic action 0 t ( ,*>les ,macl>51 publi%$ 9 #ahci4ie ,?is au?or cle>ly recogniz$ ! lat] age & uncon=mable position ( ! co>se mass ( agglom]ate pi]c$ by ! basalt ( ! apex1 & po9t$ out ! evid5ce ( ! upheaval & d5udation ( ! old] volcanic s]ies dur+ a long int]val ( repose be=e ! late/ eruptions took place4 ,subsequ5tly ,edw>d ,=bes sugge/$ t ! upp] "p ( ! hill might be ( ,t]ti>y age4#if ,!reaft] ,i mapp$ ! gr\nd 9 detail = ! ,geological ,survey1 entirely confirm+ ! obs]vations ( ,macl>54#ig ,9 ! end x seem$ to me t ! int]val betwe5 ! two epo*s ( volcanic activity might n be s great z ,=bes _h suppos$2 & aft] trac+ ! ,p]mian v5ts ( ,ayr%ire1 ,i came to ! conclusion t ! y\ng] uncon=mable agglom]ate ( ,ar?ur ,seat 0 n improbably ,p]mian4 ,footnote #ie3 ,geology ( ,fife & ! ,lo?ians1 p4 #cd4 ,9 a repr9t ( ?is "w1 publi%$ 9 #ahff1 ! v5]able au?or briefly rem>k$ 9 a footnote t he no long] believ$ 9 ! second p]iod ( volcanic activity4 ,?is view 0 adopt$ 9 #ahge by ,pr(essor ,judd1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxxi4 p4 #aca4 ,= ! reasons /at$ 9 ! text ,i believe ,macl>5's orig9al explanation ( ! /ructure ( ! hill to be correct4 ,footnote #if3 ,=bes nev] publi%$ 8 views reg>d+ ,ar?ur ,seat1 b exp\nd$ !m to 8 class1 & expla9$ !m 9 diagrams1 "s ( :i* are pres]v$ 9 ! ,ed9burgh ,museum ( ,sci5ce & ,art1 9 association ) ! specim5s :i* he collect$ f ! hill4 ,footnote #ig3 ,%eet #cb1 ,geol4 ,survey ( ,scotl& & descriptive ,memoir4 ,see also ,rep4 ,brit4 ,assoc4 #ahfg1 address ,geol4 ,sect41 & ,mur*ison's ,siluria1 #d? edit4 p4 #cca4 ,! old] volcanic s]ies ( ?is hill has be5 brok5 ?r\gh by ! agglom]ate :i* occupies a true neck1 & is abruptly m>k$ (f f all ! rocks old] ?an itself4 ,!re is no trace ( any ( ! old] lavas or tuffs ?ick5+ t[>ds ?is v5t4 ,on ! contr>y !y are completely truncat$ by x1 & _! outcrops on ! nor? side reappe> f "u ! agglom]ate on ! s\? side4 ,_! esc>pm5ts are wrapp$ r\nd by ! agglom]ate :i* likewise fills ! head ( ! holl[ t _h be5 previ\sly worn by d5udation out ( ! /ratifi$ deposits betwe5 ! olde/ lavas4 ,!re is ?us a viol5t uncon=mability betwe5 ! lat] & ! old] volcanic rocks ( ,ar?ur ,seat4 ,! l5g? ( "t indicat$ by ?is /ratigraphical break mu/ be great4 ,!re is no kn[n discordance 9 ! ,c>bonif]\s sy/em ( ! ,lo?ians1 yet ! ,coal-measures1 ,mill/one ,grit1 ,c>bonif]\s ,lime/one s]ies & mu* ( ! ,calcif]\s ,s&/ones 7 /ripp$ f ?is hill be=e ! eruption ( ! agglom]ate4 ,x w be %[n 9 ! sequel t a ne>ly simil> am\nt ( d5udation prec$$ "s ( ! probably ,p]mian eruptions ( ,fife4 ,! agglom]ate conta9s abundant fragm5ts ( ! old] volcanic s]ies4 ,its matrix is a dull r$ gravelly detritus1 cr[d$ ) blocks ( all sizes up to a y>d or m 9 diamet]4 ,x is pi]c$ by a column or plug ( basalt1 :i* s5ds ve9s into x1 & rises to ! apex ( ! hill4 ,a beautiful oliv9e-basalt =ms ! lat]al mass ( ! ,lion's ,haun*1 :i* re/s on ! agglom]ate4 ,illu/ration3 ,fig4 #bjg4--,section %[+ ! relations ( ! lat] rocks ( ,ar?ur ,seat4 #a4 ,grey & r$di% s&/ones & %ales 7,calcif]\s ,s&/ones72 #b4 ,! lava ( ! ,long ,r[3 ! olde/ ( ! ,c>bonif]\s volcanic s]ies2 #c4 ,tuffs ( ! ,dry ,dam2 #d4 ,column> basalts ov]ly+ ! tuffs2 #e4 ,&esite lavas ( ! ea/]n half ( ,ar?ur ,seat2 #f4 ,sill ( ,h]iot ,m\nt2 #g4 ,sill ( ,salisbury ,crags2 #h4 ,sill ( ! ,dasses4 ,^! complete ! ,l[] ,c>bonif]\s volcanic s]ies 7comp>e ,fig4 #aab74 #i4 ,:ite s&/ones & black %ales1 upp] division ( ! ,calcif]\s ,s&/ones2 #aj4 ,y\ng] volcanic agglom]ate re/+ on ! d5ud$ ends ( ! old] volcanic s]ies2 #aa4 ,basalt ( ! summit s5d+ ve9s into ! agglom]ate2 #ab4 ,basalt ( ! ,lion's ,haun*4 ,9 g5]al *>act]s ! agglom]ate ( ,ar?ur ,seat resembles t ( "s ( ! y\ng] v5ts ( ,fife :i* pi]ce ! ,coal-measures & are connect$ ) tuffs t lie uncon=mably on ! ,c>bonif]\s ,lime/one4 ,on ^! v>i\s gr\nds ,i ?9k t x may be reasonably assign$ to ! same geological p]iod4 ,t a new v5t %\ld be op5$1 aft] ! lapse ( "o or m geological p]iods1 on or ne> ! site ( m anci5t volcanic orifices is an incid5t ( :i*1 z we h se51 ! geological hi/ory ( ! ,briti% ,isles furni%es a numb] ( examples4 ,x w be rememb]$ t little m ?an a mile to ! s\? ( ,ar?ur ,seat lies ! great v5t ( ! ,braid ,hills1 :i* 9 ! "t ( ! ,l[] ,old ,r$ ,s&/one gave =? su* a huge pile ( lavas & tuffs4 ,volcanic en]gy !reaft] entirely di$ away1 & 9 ?is di/rict 0 succe$$ by a prolong$ p]iod ( quiesc5ce1 dur+ :i* ! ,l[] ,old ,r$ ,s&/one 0 uprais$ & ext5sively d5ud$1 :ile ! ,upp] ,old ,r$ ,s&/one 0 deposit$4 ,at l5g?1 9 ! imm$iate neighb\rhood1 f "o or m v5ts1 ! exact site ( :i* is n c]ta9ly kn[n1 ! old] lavas & tuffs ( ,ar?ur ,seat1 ,calton ,hill & ,craiglockh>t ,hill 7 erupt$4 ,aga91 aft] ano!r va/ int]val1 a new volcano appe>$1 & ! agglom]ate & y\ng] basalts ( ,ar?ur ,seat 7 eject$ f x4 ,?is is "o ( ! mo/ /rik+ examples 9 ?is c\ntry ( ! rem>kable p]si/5ce ( volcanic en]gy 9 ! same locality4 ,!re is no evid5ce at ,ar?ur ,seat itself to fix ! geological date ( ! la/ volcanic activity ( ! hill4 ,if ! gr\p ( y\ng] rocks /ood alone1 ) no o!r trace ( po/-,c>bonif]\s eruptions 9 ! surr\nd+ di/rict1 a plausible conjecture z to its age w\ld n be easily (f]$4 ,b 9 reality x is n a solit>y example ( su* rocks2 = )9 sight1 on ! opposite side ( ! ,fir? ( ,=?1 its c\nt]p>ts may be se54 ,to ! description ( ^! num]\s & cle>] illu/rations ,i n[ proce$4 ,! ,ea/ ( ,fife is rem>kable = a l>ge assemblage ( volcanic v5ts1 :i*1 unlike ^? 9 ,ayr%ire & ,ni?sdale1 /& alone1 _! sup]ficial ejections hav+ be5 remov$ by d5udation1 & no connection be+ traceable betwe5 !m & any ,p]mian s&/ones4 ,! v5ts fill$ up ) agglom]ate & pi]c$ ) plugs & ve9s ( basalt1 rise ?r\gh ! ,c>bonif]\s rocks1 b h left no record = precisely def9+ _! geological age4 ,on ! "o h&1 x is q c]ta9 t 9 ?is di/rict volcanic eruptions took place dur+ ! e>li] half ( ! ,c>bonif]\s p]iod4 ,to ! nor? ( ,l>go1 & /ill m di/9ctly to ! nor?-ea/ ( ,lev51 sections occur to %[ ! contemporane\s outp\r+ ( volcanic rocks dur+ ! "t ( ! ,c>bonif]\s ,lime/one4 ,! ,lev5 section1 se5 9 a rav9e a little to ! nor?-ea/ ( ! t[n1 is specially important4 ,x pres5ts a succession ( r$ & gre5 f9e s&y tuffs1 int]/ratifi$ ) fire-clays & s&/ones1 & conta9+ a zone ( basalt 9 ! c5tre4 ,^! rocks lie n f> f ! top ( ! ,c>bonif]\s ,lime/one s]ies4 ,on ! o!r h&1 !re is equally cle> pro( ( f> lat] eruptions4 ,f ,/4 ,&rews to ,elie a *a9 ( necks may be trac$1 hav+ ! same g5]al *>act]s1 & pi]c+ alike ! ,calcif]\s ,s&/ones1 & ! old] "p ( ! ,c>bonif]\s ,lime/one s]ies4 ,t ^! v5ts mu/ 9 _m cases be long po/]ior to ! rocks among :i* !y rise1 is indicat$ by "s curi\s & int]e/+ k9ds ( evid5ce4 ,!y are (t5 replete ) angul> fragm5ts ( %ale1 s&/one & lime/one1 ( precisely ! same m9]al *>act]s z ! surr\nd+ /rata1 & conta9+ ! same organic rema9s 9 an id5tical /ate ( fossilization4 ,x is cle> t ^! /rata mu/ h _h v mu* _! pres5t li?ological aspect be=e ! v5ts 7 op5$ ?r\gh !m4 ,aga91 ! necks may (t5 be obs]v$ to rise among mu* contort$ /rata1 z1 = example1 along ! cre/ ( a %>p anticl9al ar*1 or across a syncl9al bas94 ,! ,c>bonif]\s rocks mu/ ?us h be5 consid]ably plicat$ be=e ! "t ( ! volcanic eruptions4 ,9 ! next place1 ! v5ts (t5 occur on l9es ( dislocation )\t be+ affect$ !reby4 ,!y mu/ be po/]ior1 h[ev]1 n only to ^! dislocations1 b also to mu* subsequ5t d5udation1 inasmu* z _! mat]ials ov]spread ! rocks on ea* side ( a fault )\t displacem5t4 ,h5ce we conclude ) confid5ce1 t a great deal ( volcanic activity 9 ! ,ea/ ( ,fife mu/ h be5 po/]ior to mo/1 if n all1 ( ! ,c>bonif]\s p]iod4 ,illu/ration3 ,fig4 #bjh4--,section 9 brooks betwe5 ,bonnyt[n & ,balda/>d1 ,l>go4 a1 ,s&/one %ales & coals ( ,c>bonif]\s ,lime/one s]ies2 b1 uncon=mable tuff4 ,9 ! neighb\rhood ( ,l>go1 fur!r important evid5ce is pres5t$1 confirm+ & ext5d+ ?is conclusion4 ,! highe/ memb] ( ! ,upp] ,coal-measures1 consi/+ ( v>i\s r$ s&/ones1 ) r$ & purple clays1 %ales1 ?9 coals & iron/ones1 is prolong$ f ! ,fife coal-field 9 a tongue :i* ext5ds ea/w>d beyond ! village ( ,l[] ,l>go4 ,x is well display$ on ! %ore1 :]e e b$ may be foll[$ 9 succession along ! bea* = a space ( ne>ly two miles4 ,two volcanic necks1 pres5t+ ! same features z ^? :i* pi]ce ! old] portions ( ! ,c>bonif]\s sy/em to ! ea/1 rise ?r\gh ^! r$ rocks4 ,we are ?us c>ri$ n only beyond ! "t ( ! ,c>bonif]\s ,lime/one1 b beyond ! close ( ! v late/ /age ( ! ,c>bonif]\s p]iod 9 ,c5tral ,scotl&4 ,connect$ ) ^! & o!r v5ts f>!r nor?1 !re is a l>ge area ( tuff :i* has be5 ?r[n out ^u ! fault$ & greatly d5ud$ ,c>bonif]\s rocks4 ,x may be trac$ pass+ f ! r$ ,upp] ,coal-measures across ! l>ge fault :i* "h sep>ates t =mation f ! ,c>bonif]\s ,lime/one1 & ext5d+ inl& a?w>t diff]5t horizons ( ! latt] s]ies4 ,outly+ fragm5t>y cakes ( x may be se5 re/+ on ! upturn$ edges ( ! s&/ones1 %ales & coal-seams1 ev5 at a di/ance ( "s miles t[>ds ! nor?-we/1 prov+ t ! fragm5t>y mat]ials dis*>g$ f ! v5ts spread ov] a consid]able area4 ,! accompany+ section 7,fig4 #bjh7 may s]ve z an illu/ration ( ! relation betwe5 ?is %eet ( b$d$ tuff & ! und]ly+ rocks4 ,?\gh int]/ratifi$ volcanic rocks occur 9 ! ,c>bonif]\s sy/em ( ! ,ea/ ( ,fife1 no connection has be5 trac$ betwe5 !m & any ( ! v5ts n[ ref]r$ to4 ,:ile none ( ^! v5ts c be prov$ to be ( ,c>bonif]\s age1 x is ( c\rse possible t su* may be ! true date ( "s ( !m4 ,o!rs1 nev]!less1 & probably mu* ! l>ge/ numb]1 judg$ f ! data j giv51 may be reg>d$ z probably po/-,c>bonif]\s4 ,^? :i* happ5 to rise ?r\gh ! upp]mo/ ,coal-measures d n appe> to be di/+ui%able by any ess5tial *>act]s f ^? :i* pi]ce indiff]5tly ! ,c>bonif]\s ,lime/one s]ies & ,calcif]\s ,s&/ones ( ! ,ea/ ( ,fife4 ,!y seem to be all "o connect$ aggregate1 resembl+ ea* o!r alike 9 _! ext]nal *>act]s1 int]nal /ructure & compon5t mat]ials1 & ! limit ( _! age mu/ be det]m9$ by ! geological horizon ( ! y\nge/ =mation :i* !y trav]se4 ,by ?is process ( reason+ ,i rea* ! conclusion t ?is rem>kable s]ies ( old volcanoes 9 ! ,ea/ ( ,scotl& n improbably dates f ! same "t z t ( ,ayr%ire & ,ni?sdale1 already describ$4 ,illu/ration3 ,fig4 #bji4--,view ( ,l>go ,law f ! ea/ 7! crag on ! left1 at ! base ( ! cone1 is a portion ( a basalt-/ream4 ,see ,fig4 #bbf74 ,"s idea ( ! importance & int]e/ ( ! volcanic area ( ,ea/]n ,fife may be ga!r$ f ! fact t 9 a space ( ab\t #gj squ>e miles no few] ?an #fj necks may be c\nt$1 & o!rs are probably conceal$ bel[ ! drift-deposits :i* cov] s mu* ( ! int]ior ( ! c\ntry4 ,! area ( ?is rem>kable display ext5ds f ,/4 ,&rews ,bay & ! ,vale ( ! ,ed5 s\?w>ds to ! coa/ ( ! ,fir? ( ,=? betwe5 ,lund9 ,l9ks & ,/4 ,monans4 ,all ov] ! inl& tract ! necks =m m or less m>k$ em95ces1 ( :i* ! l>ge/ are conspicu\s l&m>ks f ! s\!rn side ( ! ,fir?4 ,b ! di/+ui%+ *>act]i/ic ( ! area is ! display ( ! necks along ! coa/1 :]e1 9 a s]ies ( natural dissections1 _! =m1 composition1 int]nal /ructure & relations to ! surr\nd+ rocks h be5 laid op5 9 su* cle>ness & v>iety z h be5 met ) 9 ! volcanic records ( no o!r geological p]iod )9 ! compass ( ^! isl&s4 ,z ?is di/rict ?us possesses a s+ul> int]e/ & value = ! /udy ( volcanic v5ts1 ,i %all ent] 9 "s detail into ! description ( ! sections s admirably laid b>e4 ,illu/ration3 ,fig4 #baj4--,view ( small neck 9 ,calcif]\s ,s&/ones1 on ! %ore1 ?ree miles ea/ f ,/4 ,&rews4 7,?is illu/ration1 likewise ,figs4 #bab1 #baf1 #bai1 #bba1 #bbb1 #bbe & #bbg are f photographs tak5 = ! ,geological ,survey by ,mr4 ,r4 ,lunn47 ,z 9 ,ayr%ire1 ! necks 9 ! ,ea/ ( ,fife g5]ally rise z isolat$ conical or dome-%ap$ hills1 ) smoo? grassy slopes1 b :]e a dyke or boss ( basalt occurs 9 !m1 x usually /&s out z a crag or knoll4 ,l>go ,law 7,fig4 #bji7 may be tak5 z a s+ul>ly p]fect example ( ! cone-%ap$ neck4 ,?is hill1 h[ev]1 comprises m ?an "o v5t4 ,! mass ( tuff ( :i* x consi/s probably includes at lea/ ?ree di/9ct funnels ( dis*>ge1 & surr\nd+ x !re /ill rema9s a good deal ( ! fragm5tal mat]ial t ga!r$ ar\nd ^! v5ts & is n[ se5 to lie uncon=mably ^u ! ,c>bonif]\s =mations 7,fig4 #bjh74 ,!re mu/ be a total area ( n mu* less ?an f\r squ>e miles ov] :i* tuff occupies ! surface ( ! gr\nd4 ,:ile ! ,fife necks possess ! great advantage ( hav+ be5 laid b>e by ! sea1 _! frequ5t small size on ! coa/ all[s _! :ole area to be exam9$4 ,z illu/rations ( ^! little v5ts1 two plates are "h giv5 f ! coa/-l9e to ! ea/ ( ,/4 ,&rews1 :]e a numb] ( small necks ( agglom]ate h be5 plant$ among ! plicat$ ,calcif]\s ,s&/ones4 ,9 ,fig4 #baj ! abrupt truncation ( ! s&/ones by ! volcanic rock is well %[n4 ,! /rata on ! "r h be5 brok5 ?r\gh1 & ! sea has ind5t$ a small gully along ! wall ( ! old volcanic funnel4 ,! s&/ones 9 front1 h[ev]1 /ill adh]e firmly to ! agglom]ate1 :i* rises above !m z a rugg$ mass ( rock4 ,9 ,fig4 #bab ! edge ( ! v5t c be trac$ p>tly 9 section & p>tly 9 plan = ab\t half ( its circumf]5ce4 ,on ! "r h&1 ! actual wall ( ! funnel is visible :]e ! false-b$d$ s&/ones are %>ply cut (f by ! agglom]ate4 ,9 front ! /rata appe> 9 plan on ! bea*1 & _! l$ges c be se5 to ! left /rik+ at ! m>g9 ( ! neck4 ,illu/ration3 ,fig4 #baa4--;,gr\nd-plan ( ,p]mian volcanic v5ts4 ,illu/ration3 ,fig4 #bab4--,small neck 9 ,calcif]\s ,s&/ones a little ea/ f ! ,rock & ,sp9dle1 two & a half miles ea/ f ,/4 ,&rews4 ,! %ape ( ! ,fife v5ts is1 z usual1 g5]ally circul> or oval2 b is subject to consid]able irregul>ity4 ,! coa/-section betwe5 ,l>go & ,/4 ,monans exposes _m gr\nd-plans ( !m1 & p]mits _! irregul>ities to be closely exam9$4 ,! accompany+ figure 7,fig4 #baa7 exhibits "s *>act]i/ic =ms4 ,ecc5tricities ( outl9e no d\bt arose f ! irregul> way 9 :i* ! rocks yield$ to ! =ces ( explosion dur+ ! pi]c+ ( a volcanic orifice4 ,?is is (t5 well %[n by ! ve9s & ne/s ( tuff or agglom]ate :i* h be5 =c$ into ! r5ts or s9uosities ( ! orifices4 ,9 o!r cases1 h[ev]1 x is probable t1 z among ! ,ayr%ire necks1 & ^? ( ,c>bonif]\s age already cit$1 :at appe>s n[ z "o volcanic neck 0 ! result ( a %ift+ ( ! actual funnel ( dis*>ge1 s t ! neck really repres5ts sev]al closely adjac5t v5ts4 ,! case ( ,l>go ,law has be5 already notic$4 ,! necks at ,kellie ,law 7,fig4 #bac7 %[ cle>ly ! same /ructure1 ! ,law itself 7#a7 probably consi/+ ( two contigu\s v5ts1 :ile a ?ird 7#b7 =ms a small] cone imm$iately to ! ea/4 ,su* a slight lat]al displacem5t ( ! v5t has be5 notic$ at _m ,t]ti>y & rec5t volcanic orifices4 ,9 ! isl& or p59sula ( ,volcanello1 = example1 ?ree crat]s indicate successive %ift+s ( ! v5t1 ! mo/ p]fect ( !m m>k+ ! late/ & dim9i%+ phase ( volcanic activity 7,fig4 #bad1 comp>e ,fig4 #bi1 vol4 i41 p4 #gj74 ,illu/ration3 ,fig4 #bac4--,plan ( volcanic necks at ,kellie ,law1 ea/ ( ,fife1 on ! scale ( ?ree in*es to "o mile4 #a1 ,kellie ,law 7tuff72 #b1 ,c>nbee ,law 7tuff72 #c1 #d1 #e1 small tuff necks2 ,b ,b1 basalt dykes & bosses2 c c1 coal-seams2 l1 lime/one2 f1 fault4 ,! arr[s m>k ! dip ( ! /rata ?r\gh :i* ! necks h be5 drill$4 ,illu/ration3 ,fig4 #bad4--,plan ( ! crat]s 9 ,volcanello1 ,lip>i ,isl&s4 ,! ,fife necks v>y f only a few y>ds up to p]haps #djjj feet 9 diamet]4 ,"o ( ! smalle/ & mo/ completely expos$ occurs on ! %ore at ,new>k ,ca/le1 ne> ,/4 ,monans4 ,x measures only #fj y>ds 9 l5g? by ab\t #cg y>ds 9 bread?4 ,a gr\nd-plan ( x is giv5 9 ,fig #bbd4 ,/ill small] is ! neck at ,buddo ,ness1 on ! coa/ ea/ ( ,/4 ,&rews1 :i* measures only #bj y>ds across4 ,f ! way 9 :i* ! v5ts h be5 dissect$ by ! sea along ! ,fife coa/1 ! geologi/ is enabl$ to /udy 9 m9ute detail ! effects ( ! volcanic op]ations ^u ! /rata ?r\gh :i* ! funnels h be5 drill$4 ,consid]able v>iation may be obs]v$ 9 ! nature & am\nt ( *ange4 ,sometimes ! orifice has be5 made )\t any noticeable alt]ation ( ! s&/ones1 %ales & lime/ones1 :i* reta9 _! dip & /rike up to ! v wall ( ! *imney4 ,usually !re is m or less jumbl+ & cru%+ ( ! /ratification1 & (t5 a consid]able am\nt ( induration4 ,z a typical example ( ^! effects ,i give a section f ! m>g9 ( ! neck ( tuff on ! ea/ side ( ,elie ,h>b\r 7,fig4 #bae74 ,"h ! s&/ones & %ales 7a7 h be5 d\bl$ ov] & dragg$ d[n aga9/ ! tuff 7b74 ,!y h likewise be5 h>d5$ into a k9d ( qu>tzite1 & ?is alt]ation ext5ds = ab\t #bj to #cj feet f ! edge ( ! neck4 ,illu/ration3 ,fig4 #bae4--,section ( ! /rata at ! edge ( ! volcanic v5t on ! ea/ side ( ,elie ,h>b\r4 ,! mat]ial :i* has fill$ up ! v5ts is almo/ entirely fragm5tal1 v>y+ f a co>se agglom]ate to a f9e volcanic tuff4 ,"s m9or necks h be5 completely or 9 great "p fill$ ) angul> debris ( ! ord9>y rocks ( ! neighb\rhood4 ,9 ! we/]n neck on ! ,l>go %ore1 = example1 :i* rises ?r\gh ! r$ rocks ( ! ,upp] ,coal-measures1 ! mat]ial consi/s l>gely ( fragm5ts ( r$ s&/one1 clay & %ale4 ,betwe5 ,elie & ,/4 ,monans1 "s ( ! necks are fill$ almo/ :olly ) debris ( black %ale & encr9al lime/one4 ,!re does n appe> to be any relation betwe5 ! diamet] ( a funnel & ! size ( ! blocks t n[ fill x4 ,"s ( ! l>g] necks1 = example1 consi/ ( comp>atively f9e tuff4 ,! ,buddo ,ness1 on ! o!r h&1 ?\gh s small a v5t1 is pack$ ) blocks ( %ale six feet long1 :ile ! s&/one ?r\gh :i* ! orifice has be5 drill$ passes1 z usual1 into qu>tzite = sev]al y>ds away f ! edge4 ,z an example ( ! g5]al aspect pres5t$ by "o ( ! co>se agglom]ates 9 ! necks ( ! ,fife coa/1 a view is giv5 9 ,fig4 #baf ( a portion ( ! neck at ,ardross1 ab\t two miles ea/ f ,elie4 ,?is ?or\ghly volcanic accumulation is "h %[n to consi/ ( blocks ( all sizes heap$ toge!r )\t any def9ite arrangem5t4 ,illu/ration3 ,fig4 #baf4--;,agglom]ate ( neck on %ore at ,ardross1 two miles ea/ f ,elie4 ,s9ce ! fir/ /age 9 ! hi/ory ( ! v5ts has be5 ! p]=ation ( ! solid cru/ by explosion1 & ! consequ5t production ( debris f ! disrupt$ rocks1 we may hope to detect und]nea? ! pile ( ?or\ghly volcanic ejections1 traces ( ! fir/ explosions4 ,i h be5 mu* /ruck ) ! fact t 9 ! ,ea/ ( ,fife su* traces may frequ5tly be f\nd "h & !re )9 ! out] bord] ( ! v5ts4 ,at ,l>go1 & aga9 betwe5 ,elie & ,/4 ,monans1 x may be notic$ t ! mass ( mat]ial adh]+ to ! wall ( a neck1 expos$ 9 gr\nd-plan ^u ! bea*1 (t5 consi/s l>gely1 or ev5 :olly1 ( debris ( s&/one1 %ale & lime/one1 :ile ! c5tral & *ief mass is made up ( gre5 tuff or agglom]ate1 ) occasional pieces ( ! surr\nd+ /ratifi$ rocks scatt]$ ?r\gh x4 ,x seems probable1 !re=e1 t ! sections ( ^! ,fife necks1 laid b>e on ! pres5t %ore1 d n lie f> bel[ ! orig9al crat]-bottoms4 ,"s light might be expect$ to be ?r[n ^u ! ph5om5a 9 an active volcanic *imney by ! condition ( ! fragm5ts ( recognizable s$im5t>y rocks imb$d$ 9 ! eject$ debris :i* has fill$ up ! orifice4 ,b ! assi/ance f ?is s\rce is nei!r s full nor s reliable z c\ld be wi%$4 ,9 "s ( ! ,fife v5ts1 inde$1 ! fragm5ts ( %ale1 s&/one & o!r s$im5t>y /rata are s un*ang$ t !y _c on a fre% fracture be di/+ui%$ f ! adjac5t p>5t /rata4 ,! ,spirif]s1 ,l+ul1 cr9oids1 cyprid-cases1 ganoid scales & o!r fossils are (t5 z fre% & p]fect 9 ! fragm5ts ( rock imb$d$ 9 tuff z !y are 9 ! rock 9 situ4 ,9 "s cases1 h[ev]1 di/9ct1 & occasionally ev5 extreme1 metamorphism may be detect$1 v>y+ 9 int5sity f m]e induration to ! production ( a cry/all9e texture4 ,! am\nt ( alt]ation has dep5d$ n m]ely ^u ! heat ( ! volcanic v5t1 b also 9 great measure ^u ! susceptibility ( ! fragm5ts to und]go *ange & ! duration ( _! exposure to x4 ,dr4 ,h$dle has comput$ ! temp]ature to :i* fragm5ts ( %ale1 etc41 9 tuff-necks ( ! ,fife coa/ h be5 subject$4 ,he f\nd t ! bitum9\s %ales h lo/ all _! illum9ants1 & ( organic matt] h reta9$ only "s black c>bonace\s p>ticles2 t ! encr9al lime/ones h become granul> & cry/all9e2 t ! s&/ones pres5t !mselves z qu>tzite1 & t black c>bonace\s clays %[ e /age ( a passage into ,lydian-/one4 ,he inf]r$ f ! slight dep? to :i* ! alt]ation has p5etrat$ ! l>g] calc>e\s fragm5ts1 t ! heat to :i* !y 7 expos$ mu/ h be5 b ( %ort cont9uance4 ,z ! result ( 8 exp]im5ts1 he conclud$ t ! temp]ature at :i* ! fragm5ts 7 f9ally eject$ f ! volcanic v5ts probably lay betwe5 #ffj & #ijj ,fahr4#ih ,footnote #ih3 ,trans4 ,roy4 ,soc4 ,ed94 vol4 xxviii4 p4 #dhg4 ,x may be p]haps legitimate to inf] t1 :ile ! fragm5ts t fell back into ! volcanic funnel1 or :i* 7 deta*$ f ! sides ( ! v5t1 aft] hav+ be5 expos$ = "s "t to int5se heat "u consid]able pressure1 w\ld suff] m or less metamorphism1 ^?1 on ! o!r h&1 :i* 7 dis*>g$ by ! ri=m explosions f ! cool upp] cru/1 on ! fir/ outbur/ ( a v5t1 w\ld n exhibit any trace ( su* a *ange4 ,:]e1 !re=e1 we meet ) a neck full ( fragm5ts ( unalt]$ /ratifi$ rocks1 we may suppose x to h be5 t ( a %ort-liv$ volcano2 :]e1 on ! o!r h&1 ! fragm5ts are few & mu* alt]$1 !y may m>k ! site ( a v5t :i* cont9u$ long] active4 ,! metamorphism ( ! fragm5t>y cont5ts ( a volcanic funnel by ! action ( asc5d+ vap\rs has already be5 describ$ 9 ! case ( "o ( ! v5ts ( ! ,c>bonif]\s plateaux 7vol4 i4 p4 #djd74 ,"o ( ! mo/ curi\s & puzzl+ features 9 ! cont5ts ( ! tuff necks ( ! ,fife coa/ is ! occurr5ce !re ( cry/als & fragm5ts ( m9]als1 (t5 ( consid]able size1 :i* d n be> evid5ce ( hav+-be5 =m$ 9 situ1 b h und\bt$ly be5 eject$ ) ! o!r detritus4 ,dr4 ,h$dle has notic$ ! fact1 & has describ$ "s ( ! m9]als :i* occur 9 ?is way4 ,! foll[+ li/ comprises ! species :i* he & ,i h f\nd3-- ,hornbl5de1 9 r\nd$ fragm5ts ( a glassy black cleavable v>iety4 ,augite1 sometimes 9 small cry/als1 else:]e 9 r\nd$ fragm5ts ( an augitic glass4 ,or?oclase 7,sanid9e71 abundant 9 worn tw9 cry/als 9 ! tuffs ( ! ea/ ( ,fife4 ,plagioclase4 ,biotite4 ,pyrope1 9 ! tuffs 7& m r>ely 9 ! basalts7 ( ,elie4 ,nigr9e1 common 9 "s ( ! dykes1 m r>ely 9 ! tuffs ( ,elie4 ,saponite1 ,delessite & o!r decomposition products4 ,semi-opal1 "o specim5 f\nd 9 ! lat] 7,p]mian87 agglom]ate ( ,ar?ur's ,seat4 ,asphalt1 abundant at ,k9craig1 ne> ,elie4 ,fragm5ts ( wood1 ) /ructure well pres]v$1 may be includ$ "h4 ,dr4 ,h$dle has describ$ f ! neck ( tuff at ,k9kell1 ne> ,/4 ,&rews1 l>ge tw9 cry/als ( a glassy or?oclase1 :i* are inv>iably mu* worn1 & pres]ve only rudely ! =m ( cry/als4 ,he ju/ly rem>ks t !y h no connection ) drusy cavity1 exfiltration ve91 or ) any o!r m9]al1 & look z if a portion ( _! sub/ance has be5 dissolv$ away4 ,int]nally1 h[ev]1 !y are q fre% & brilliant 9 lu/re1 ?\gh sometimes mu* fissur$4#ii ,footnote #ii3 ,trans4 ,roy4 ,soc4 ,ed94 vol4 xxviii4 p4 #bbc4 ,! tuffs at ,elie are full ( simil> cry/als4 ,i obta9$ f "o ( ! necks ea/ ( t village a specim5 :i* measures #d in*es 9 l5g?1 #c-a_/b 9 bread?1 & #b-a_/d 9 ?ickness1 & weighs ab\t #b lbs4 ,x is1 h[ev]1 a well-/riat$ felsp>4 ,f ! same tuff ,i procur$ an or?oclase tw9 9 ! ,c>lsbad =m4 ,all ! felsp> pieces1 ?\gh fre% & brilliant int]nally1 h ! same r\nd$ & abrad$ ext]nal appe>ance4 ,! fragm5ts ( hornbl5de =m a *>act]i/ic feature 9 sev]al ( ! ,elie dykes 7to be aft]w>ds describ$71 & 9 ! neighb\rhood ( ^! intrusive rocks occur m sp>+ly 9 ! tuff4 ,x is a glossy-black cleavable m9]al1 9 r\nd$ pieces ( all sizes1 up to t ( a small egg4 ,dr4 ,h$dle obta9$ a cleavage angle ( #abd #ai'1 & f\nd on analysis t ! m9]al 0 hornbl5de4#ajj ,footnote #ajj3 ,op4 cit4 xxviii4 p4 #ebb4 ,augite occurs sp>+ly 9 two =ms among ! rocks4 ,i h obta9$ small cry/als f ! r$ agglom]ate on ! s\? side ( ,ar?ur ,seat1 recall+ 9 _! g5]al appe>ance ^? ( ,somma4 ,lumps ( an augitic glass h be5 f\nd by ,dr4 ,h$dle1 sometimes z l>ge z a pigeon's egg1 9 two ( ! dykes at ,elie1 & 9 ! tuff at ! ,k9kell neck1 ne> ,/4 ,&rews4 ,he obs]v$ ! same sub/ance at ! ,giant's ,causeway1 bo? 9 ! basalt & scatt]$ ?r\gh "o ( ! int]/ratifi$ b$s ( r$ bole4 ,mu* l>g] r\nd$ masses ( a simil> augitic glass1 b ) a di/9ct trace ( cleavage1 h already be5 ref]r$ to z occurr+ 9 a volcanic v5t ( ,upp] ,old ,r$ ,s&/one age at ,john o' ,groat's ,h\se4#aja ,footnote #aja3 ,op4 cit4 xxviii4 pp4 #dha et seq41 & ante1 vol4 i4 p4 #ceb4 ,biotite is n a r>e m9]al 9 "s tuffs4 ,x may be obta9$ 9 ,l[] ,c>bonif]\s tuffs ( ,dunb>1 9 plates ne>ly an in* broad2 b ! l>ge/ specim5 ,i h obta9$ is "o f ! same ,elie v5t :i* yield$ ! l>ge felsp> fragm5t4 ,x measures #b-a_/b #b #a_/b in*es4 ,^! mica tables1 l ! o!r m9]als1 are abrad$ specim5s4 ,t ^! v>i\s m9]als 7 eject$ z fragm5ts1 & h n be5 =m$ 9 situ1 is ! conclusion =c$ ^u ! obs]v] :o exam9es c>efully _! mode ( occurr5ce4 ,"s ( !m 7 c>ri$ up to ! surface by liquid volcanic mud1 & appe> 9 dykes ( t mat]ial l plums 9 a cake4 ,b ev5 !re !y pres5t ! same evid5ce ( attrition4 ,!y assur$ly h n be5 =m$ 9 ! dykes any m ?an 9 ! surr\nd+ tuff4 ,9 bo? cases !y are extrane\s objects :i* h be5 accid5tally involv$ 9 ! volcanic rocks4 ,dr4 ,h$dle rem>ks t ! occurr5ce ( ! worn pieces ( or?oclase 9 ! tuff is an enigma to him4 ,i h be5 z unable to frame any satisfactory explanation ( x4#ajb ,footnote #ajb3 ,occasionally ! cry/als c be mat*$ 9 "s lava-=m rock ( ! same volcanic area2 b _m ( !m h no su* c\nt]p>ts4 ,see vol4 i4 p4 #fb & note4 ,illu/ration3 ,fig4 #bag4--;,gr\nd-plan ( volcanic neck1 ,elie ,h>b\r1 %[+ circul> deposition ( ! /ratification4 ,t1 ,tuff ( ! neck1 ! arr[s %[+ its inw>d dip2 ,b ,b1 ,dykes2 ,s1 ,s&/ones & %ales1 ?r\gh :i* ! neck has be5 op5$4 ,x might h be5 ?\ght t )9 ! ?roat ( a volcano1 if 9 any circum/ances1 loose mat]ials %\ld h tak5 an indef9ite amorph\s aggregation4 ,&1 z has be5 %[n 9 ! =ego+ *apt]s1 ?is is usually ! case :]e ! mat]ials are co>se & ! v5t small4 ,oblong blocks are f\nd /uck on end1 :ile small & l>ge are all mix$ confus$ly toge!r4 ,b 9 num]\s cases :]e ! tuff is m gravelly 9 texture1 & sometimes ev5 :]e x is co>se1 traces ( /ratification may be obs]v$4 ,lay]s ( co>se & f9e mat]ial succe$ ea* o!r1 z !y are se5 to d among ! ord9>y int]/ratifi$ tuffs4 ,! /ratification is usually at high angles ( incl9ation1 (t5 v]tical4 ,s di/9ctly d ! l9es ( deposit appe> amid ! confus$ & jumbl$ masses1 t an obs]v] may be tempt$ to expla9 ! problem by suppos+ ! tuff to belong n to a neck1 b to an int]b$d$ deposit :i* has someh[ be5 brok5 up by dislocations4 ,t ! /ratification1 h[ev]1 belongs to ! orig9al volcanic v5ts !mselves is made exce$+ly cle> by "s ( ! coa/-sections 9 ! ,ea/ ( ,fife4 ,on bo? sides ( ,elie1 examples occur 9 :i* a di/9ct circul> disposition ( ! b$d+ c be trac$ correspond+ to ! g5]al =m ( ! neck4 ,! accompany+ gr\nd-plan 7,fig4 #bag7 repres5ts ?is /ructure z se5 9 ! neck :i* =ms ! headl& at ,elie h>b\r4 ,alt]nations ( co>se & f9e tuff ) b&s ( co>se agglom]ate1 dipp+ at angles ( #fj & upw>ds1 may be trac$ r\nd ab\t half ( ! circle4 ,! incomplete "p may h be5 de/roy$ by ! =mation ( ano!r contigu\s neck imm$iately to ! ea/4 ,to ! we/ ( ,e>lsf]ry ano!r l>ge1 b also imp]fect1 circle may be trac$ 9 "o ( ! %ore necks4 ,a qu>t] ( a mile f>!r we/ rises ! great cliff-l9e ( ,k9craig1 :]e a l>ge neck has be5 cut op5 into a range ( precipices #bjj feet high1 z well z into a tide-wa%$ plat=m m ?an half a mile long4 ,! inw>d dip & high angles ( ! tuff are admirably laid b>e along t portion ( ! coa/-l9e4 ,! section 9 :i* almo/ e b$ c be se51 & :]e1 !re=e1 !re is no ne$ = hypo!tical re/oration1 is z %[n 9 ,fig4 #bah4 ,i h already ref]r$ to ! frequ5tly abundant pieces ( /ratifi$ tuff1 f\nd z eject$ blocks 9 v5ts fill$ ) tuff1 & to ! d]ivation ( ^! blocks f tuff orig9ally deposit$ )9 ! crat]4 ,!re c1 ,i ?9k1 be little hesitation 9 reg>d+ ! /ratification ( ^! ,fife v5ts z a record ( successive deposits ( volcanic detritus inside ! v5ts4 ,! g5]al dip inw>ds f ! out] rim ( ! v5t /rik+ly recalls t ( "s mod]n volcanoes4 ,by way ( illu/ration1 ,i give "h a section ( "p ( ! out] rim ( ! crat] ( ! ,isl& ( ,volcano1 sket*$ by myself 9 ! ye> #ahgj :ile asc5d+ ! m\nta9 f ! nor? side 7,fig4 #bbj74 ,! crat] wall at ?is po9t consi/s ( two di/9ct p>ts--an old] tuff 7a71 :i* may h be5 9 great measure cle>$ out ( ! crat] be=e ! ejection ( ! new] tuff 7b74 ,! latt] lies on ! out] slope ( ! cone at ! usual angle ( #cj4 ,x folds ov] ! cre/ ( ! rim1 & dips d[n to ! flat tuff-cov]$ crat] bottom1 at an angle ( #cg4 ,^! are its natural angles ( repose4 ,illu/ration3 ,fig4 #bah4--,section across ! great v5t ( ,k9craig1 ,elie1 on a true scale1 v]tical & horizontal1 ( six in*es to a mile4 #a1 ,s&/ones1 %ale1 etc41 ( ,l[] ,c>bonif]\s age1 plung+ d[n t[>d ! neck ,t2 ,b1 column> basalt1 %[n also 9 ,figs4 #bbc & #bbe4 ,illu/ration3 ,fig4 #bai4--;,dyke 9 volcanic neck1 on ! bea*1 ,/4 ,monans4 ,illu/ration3 ,fig4 #bbj4--,section ( "p ( crat] rim1 ,isl& ( ,volcano4 ,apply+ mod]n analogies ( ?is k9d1 ,i h be5 l$ to conclude t ! /ratification s conspicu\s 9 ! tuff ( ! v5ts 9 ! ea/ ( ,fife & 9 ! ,c>bonif]\s s]ies ( ! ,lo?ians belongs to ! int]ior ( ! crat] & ! upp] "p ( ! volcanic funnel4#ajc ,^! /ratifi$ tuffs1 on ?is view ( _! orig91 mu/ be reg>d$ z rema9s ( ! b$s ( du/ & /ones :i* ga!r$ )9 ! crat] & volcanic orifice1 & :i*1 on ! cessation ( volcanic action1 sometimes rema9$ 9 _! orig9al position1 or 7 dislocat$ & slipp$ d[n into ! cavity b5ea?4 ,t ! tuffs consolidat$ on slopes1 p]haps q z /eep z ^? ( ,volcano1 is n[ & !n indicat$ by an int]e/+ /ructure4 ,! l>g] /ones imb$d$ 9 ! lay]s ( tuff may be obs]v$ to h on _! fronts 9 "o direction a small heap ( co>se gravelly debris1 :ile f9e tuff is heap$ up aga9/ _! opposite side4 ,?is arrangem5t d\btless po9ts to deposit on a slope ( loose debris1 f :i* ! l>g] blocks protrud$ s z to arre/ ! small] /ones1 & all[ ! f9e du/ to ga!r beh9d4 ,footnote #ajc3 ,fur!r illu/rations ( ?is *>act]i/ic /ructure ( "s v5ts w be f\nd 9 ! acc\nt ( ! ,t]ti>y v5ts ( ! ,f>oe ,isles 9 ,*apt] xli4 ,see also ! rem>ks 9 ! introductory *apt]s1 vol4 i4 p4 #fc4 ,if ! inf]5ce be correct1 t ! /ratification "h describ$ belongs to ! old crat]s or ! upp] p>ts ( ! funnels1 x furni%es additional evid5ce ( ! wide int]val ( "t t elaps$ betwe5 ! deposition ( ! ,c>bonif]\s /rata & ! outbreak ( ^! v5ts4 ,dur+ t int]val prolong$ d5udation r$uc$ ! upturn$ ,c>bonif]\s ,lime/one s]ies to ne>ly its pres5t =m ( surface1 & any mat]ials dis*>g$ f ! v5ts ov] ! surr\nd+ gr\nd w\ld obvi\sly lie ) a viol5t uncon=mability on ! rocks bel[4 ,! frequ5t great di/urbance 9 ! b$d+ ( ! tuff )9 ! v5ts may be connect$ ) "s k9d ( collapse1 subsid5ce or %r9kage ( ! mat]ials 9 ! funnel bel[4 ,t a movem5t ( ?is nature did take place is %[n by ! rem>kable b5d+ d[n ( ! /rata r\nd ! m>g9s ( ! v5ts1 :i* has be5 already describ$4 ,! m9or v5ts = ! mo/ "p conta9 only fragm5t>y mat]ials2 b ^? ( l>g] size usually pres5t masses ( lava 9 "s *>act]i/ic =ms4 ,9 n a few cases1 ! lava has ris5 9 ! c5tral pipe & has h>d5$ !re into a column ( solid rock4 ,subsequ5t d5udation1 by remov+ mo/ ( ! cone1 has left ! top ( ?is ?ick column project+ z a r\nd knoll ^u ! hill-top4 ,ar?ur ,seat pres5ts a good example ( ?is /ructure4 ,:]e ! d5udation has n proce$$ s f>1 we may /ill meet ) a remnant ( ! cake ( lava :i* sometimes ov]fl[$ ! bottom ( a crat]4 ,! summit ( ,l>go ,law af=ds indications ( ?is arrangem5t1 ! cone ( tuff be+ !re capp$ ) basalt1 evid5tly ! product ( successive /reams1 :i* well+ out irregul>ly cov]$ ! crat] bottom ) hummocks & holl[s 7,fig4 #bbf74 ,! knolls are beautifully column>1 & sometimes %[ a div]g5t arrangem5t ( ! prisms4 ,illu/ration3 ,fig4 #bba4--;,dyke ris+ ?r\gh ! agglom]ate ( a volcanic v5t2 ,k9craig1 ,elie4 ,b ! mo/ frequ5t =m assum$ by ! lava 9 ! necks is t ( ve9s or dykes runn+ z wall-l b&s ?r\gh ! tuff or agglom]ate4 ,_m admirable examples may be cit$ f ! %ore betwe5 ,l>go & ,/4 ,monans4 ,two illu/rations ( !m are giv5 9 ,figs4 #bai & #bba4 ,9 ,fig4 #bai ! dyke is ab\t f\r feet broad1 & is se5 to pres5t ! common transv]se jo9t+ z x pursues its way ?r\gh ! tuff4 ,:ite ve9s ( calcite along its m>g9 s]ve to def9e its limits4 ,its position 9 ref]5ce to ! g5]al body ( ! neck is %[n 9 ! gr\nd-plan ,fig4 #bbd4 ,! second in/ance 7,fig4 #bba7 is t ( a dyke ( basalt only "o foot wide1 :i* runs l a wall up ! agglom]ate ( ! ,k9craig neck ne> ,elie4 ,x is se5 at ! bottom ( ! cliff project+ f ! agglom]ate2 b high] up x has decay$1 leav+ its fissure z a gap+ *asm4 ,"h ! g5]al "* ( ! pyrocla/ic mat]ial is well br\ght out4 ,"o or two l>ge blocks may be se5 imb$d$ 9 x1 ! l>ge/ ly+ above :]e ! dyke b5ds away to ! left4 ,! intrud$ masses v>y 9 bread? f m]e ?readlike ve9s up to dykes sev]al y>ds 9 bread?1 :i* sometimes exp& into l>ge irregul> lumps4 ,!y g5]ally consi/ ( "s =m ( basalt2 n[ & !n1 z at ,ruddon ,po9t1 ne> ,elie1 !y are amygdaloidal2 & x may be obs]v$ among !m1 z among dykes 9 g5]al1 t :]e ! amygdaloidal texture is develop$1 x is apt to occur mo/ m>k$ly 9 ! c5tral "p ( ! ve91 ! amygdales runn+ !re 9 "o or m l9es p>allel ) ! g5]al tr5d ( ! mass4 ,t ! basalt ( ^! ve9s & dykes 0 sometimes inject$ 9 an extremely liquid condition is %[n by its frequ5tly exce$+ly close homog5e\s texture4 ,)9 ! neck on ! %ore to ! we/ ( ,l>go1 ! basalt assumes 9 places an almo/ fl9ty "*1 :i* "h & !re passes into a ?9 ext]nal v>ni% ( basalt-glass4 ,a f>!r indication ( ! liquidity ( ! orig9al rock seems to be furni%$ by ! great numb] ( includ$ extrane\s fragm5ts "h & !re to be obs]v$ 9 ! basalt4 ,b besides basalt1 o!r mat]ials may m r>ely be detect$ assum+ ! =m ( dykes or ve9s )9 ! necks4 ,?us1 at ! ,l>go neck j ref]r$ to1 /r+s ( an exce$+ly horny qu>tz-felsite accompany ! basalt--a rem>kable conjunction ( acid & basic rock )9 ! same volcanic *imney4 ,to ! ea/ ( ,elie "s dykes1 :i* /& out prom95tly on ! bea* f a plat=m worn by ! sea 9 a neck1 consi/ ( an extremely compact volcanic mud/one1 /uck full ( ! worn tw9 cry/als ( or?oclase & pieces ( hornbl5de & biotite already notic$4 ,s l is ?is rock to "o ( ! decompos+ basalts t its true fragm5tal nature may easily escape notice1 & x might be class$ confid5tly z a some:at decay$ basalt4 ,a consid]able am\nt ( a simil> f9e compact mud/one is to be se5 r\nd ! edges ( "s ( ! ,elie v5ts4 ,?is mat]ial mu/ h be5 inject$ into op5 fissures1 :]e x solidifi$4 ,!re is fur!r evid5ce ( ! pres5ce ( mud-lava 9 "s ( ! v5ts ( ,ea/ ,fife1 :]e ^! orifices conta9 a rem>kable compact volcanic s&/one1 compos$ ( ! usual detritus1 b wea!r+ into sph]oidal cru/s1 s z ext]nally to be readily mi/ak5 = "s =m ( basalt4 ,illu/ration3 ,fig4 #bbb4--,radiat+ column> dyke 9 ! tuff ( a volcanic v5t1 ,rock & ,sp9dle1 two & a half miles ea/ f ,/4 ,&rews4 ,a column> arrangem5t may (t5 be obs]v$ among ! basalt dykes4 ,:5 ! ve9 or dyke is v]tical1 ! columns ( c\rse seem pil$ 9 horizontal lay]s "o above ! o!r4 ,! expos$ side ( ! dyke !n reveals a wall ( rock1 seem+ly built up ( hexagonal or polygonal1 neatly fitt+ blocks ( masonry1 z 9 ! ,l[] ,c>bonif]\s v5t ( ! ,b9n ( ,burntisl& 7,figs4 #aff1 #afh74 ,an incl9ation ( ! dyke f ! v]tical ?r[s up ! columns to a proportional dep>ture f ! horizontal4 ,sometimes a beautiful fan-%ap$ gr\p+ ( ! prisms has tak5 place4 ,( ?is /ructure ! ,rock & ,sp9dle1 ne> ,/4 ,&rews1 pres5ts a famili> example 7,fig4 #bbb74 ,mu* m /rik+1 h[ev]1 ?\gh less kn[n1 is ! magnific5t basalt mass ( ,k9craig1 to ! we/ ( ,elie1 :]e ! columns sweep f summit to base ( ! cliff1 a height ( fully #aej feet1 l ! ,orgues d',expailly1 ne> ,le ,puy 9 ,auv]gne4 ,! g5]al position ( ?is basalt 9 ! v5t is repres5t$ 9 ! section 7,b1 ,fig4 #bah74 ,! curvature ( ! basalt is %[n 9 ,fig4 #bbc1 :i* is tak5 f ! ,elie side look+ we/w>d1 beyond ! intrusions1 to ! picturesque cliffs ( tuff4 ,! details ( ! cliff are giv5 9 ,fig4 #bbe4 ,t _m ( ! dykes s]v$ z l9es ( escape = ! basalt to ! out] slopes ( ! cones is highly probable1 ?\gh d5udation has usually de/roy$ ! pro(s ( su* an outfl[4 ,a di/9ct radiation ( ! dykes f ! c5tre ( a neck is /ill sometimes traceable4 ,?is /ructure is mo/ m>k$ on ! s\? cone ( ,l>go ,law1 :]e a numb] ( h>d ribs ( basalt project f ! slopes ( ! hill4 ,_! g5]al tr5d is su* t if prolong$ !y w\ld meet some:]e 9 ! c5tre ( ! cone4 ,on ! s\?-ea/ side ( ! hill a m9or em95ce1 t]m$ ! ,craig ,rock1 /&s out prom95tly 7,fig4 #bji74 ,x is oblong 9 %ape1 &1 l ! dykes1 po9ts t[>ds ! c5tre ( ! cone4 ,x consi/s ( a compact column> basalt1 ! columns conv]g+ f ! sides t[>ds ! top ( ! ridge4 ,x looks l ! fragm5t ( a lava-curr5t :i* fl[$ d[n a gully on ! out] slope ( ! cone 7,b' 9 ,fig4 #bbf74 ,ve9s ( basalt are n conf9$ to ! necks1 b may be se5 runn+ across ! surr\nd+ rocks4 ,! %ore at ,/4 ,monans furni%es "s in/ructive examples ( ?is "*4 ,z ! ve9s ?9 away f ! ma9 mass ( basalt !y become m close-gra9$ & light] 9 col\r1 & :5 !y ent] d>k %ales or o!r c>bonace\s rocks !y pass1 z usual1 into ! :ite e>?y clay-l :ite-trap4 ,! influ5ce ( c>bonace\s /rata 9 ?us alt]+ basic dykes & sills may be in/ructively /udi$ along ! %ore ( ! ,ea/ ( ,fife4 ,a good in/ance occurs ne> ,/4 ,monans ,*ur* 7,fig4 #bbg71 :]e a ve9 ( :ite-trap trav]ses black %ales :i* h be5 some:at jumbl$4 ,illu/ration3 ,fig4 #bbc4--,view ( "p ( ! %ore front ( ! great v5t at ,k9craig1 look+ we/w>d1 ) ! column> basalt 9 front4 ,9 a mod]n volcano no opportunity is af=d$ ( exam9+ ! contact ( ! erupt$ mat]ial ) ! rocks ?r\gh :i* ! v5t has be5 op5$4 ,b 9 ! bas9 ( ! ,fir? ( ,=?1 )9 ! area n[ "u description1 a num]\s s]ies ( coa/-sections lays b>e ?is relation 9 ! mo/ satisfactory mann]4 ,! sup]9cumb5t cones ( tuff h be5 swept away1 & we c exam9e1 z x 71 ! v roots ( ! old volcanoes4 ,! m>g9 ( a neck or volcanic v5t is ?us f\nd to be almo/ always %>ply def9$4 ,! rocks ?r\gh :i* ! funnel has be5 drill$ h be5 cut across1 z if a huge aug] _h be5 sunk ?r\gh !m4 ,?is is well display$ 9 ! beautifully p]fect neck already cit$ at ,new>k ,ca/le1 ne> ,/4 ,monans 7,fig4 #bbd74 ,! /rata ?r\gh :i* ?is neck rises consi/ ( %ales1 s&/ones1 ?9 coal & encr9al lime/ones1 dipp+ 9 a we/]ly direction at angles rang+ f #be to #fj4 ,at ! s\? end ( ! neck !y are %>ply truncat$1 z if by a fault4 ,else:]e !y are mu* jumbl$1 sl5d] ve9-l portions ( ! tuff be+ ins9uat$ among ! project+ /rata4 ,a l>ge v]tical b$ ( s&/one1 #bd y>ds long by #g y>ds broad1 /&s up z a s9u\s reef on ! ea/ side ( ! v5t 7s74 ,x is a portion ( "s ( ! surr\nd+ /rata1 b1 s f> z c be se5 at ! surface1 is entirely surr\nd$ ) agglom]ate4 ,"h & !re ! %ales h be5 excessively crumpl$1 & at ! nor? end h be5 invad$ by a ve9 ( basalt :i*1 :]e x runs ?r\gh !m1 assumes ! usual clay-l "*4 ,! /rata h be5 bl[n out1 & _! place has be5 occupi$ by a correspond+ mass ( volcanic agglom]ate4 ,b _! rema9+ truncat$ edges r\nd ! m>g9 ( ! orifice h und]gone comp>atively little alt]ation4 ,9 "s places !y h be5 h>d5$1 b _! usual texture & /ructure rema9 unaffect$4 ,illu/ration3 ,fig4 #bbd4--,plan ( volcanic neck on bea* ne> ,/4 ,monans4 ,t1 ,neck ( tuff enclos+ a mass ( s&/one 7s71 & pi]c+ s&/ones & %ales ,) b$s ( lime/one1 7l l71 & a ?9 seam ( coal 7c72 ,b1 ,basalt :ite-trap dyke4 ,! arr[s %[ ! dip ( ! /rata4 ,9 a few examples1 ! progress ( d5udation has n advanc$ s f> t ! cone _c /ill be p>tially made out amid/ its surr\nd+ masses ( tuff4 ,"o ( ! mo/ int]e/+ ( ^! is ,l>go ,law1 ( :i* an outl9e has be5 giv5 9 ,fig4 #bji4 ,! accompany+ section 7,fig4 #bbf7 repres5ts :at appe>s to me to be ! /ructure ( ?is hill4 ,ea* ( ! two n[ conjo9$ cones 0 probably 9 succession ! v5t ( ! volcano4 ,! s\!rn & r l[] em95ce1 z already m5tion$1 is trav]s$ by rib-l dykes ( basalt1 :i* po9t t[>ds its top1 :]e !re is a b$ ( ! same rock und]ly+ a capp+ ( tuff4 ,on its ea/]n declivity lies ! basalt /ream already describ$ 7p4 #hg74 ,! high] cone is surm\nt$ by a cake ( basalt :i*1 z ,i h above sugge/$1 may h solidifi$ at ! bottom ( ! late/ crat]4 ,( c\rse all trace ( ! crat] has disappe>$1 b ! g5]al conical =m ( ! volcanic mass rema9s4 ,d\btless1 /ill m ( ! old volcano w\ld h be5 remov$ by d5udation b = ! protection af=d$ to ! tuff by ! intrusion ( ! basalt4 ,! upp] dott$ l9es 9 ! figure are ins]t$ m]ely to indicate hypo!tically h[ ! cone may orig9ally h /ood4 ,on ! we/ side ! %eets ( tuff :i* 7 ?r[n out ov] ! surr\nd+ c\ntry h be5 almo/ entirely remov$1 b on ! ea/ & s\? !y /ill cov] an ext5sive area4 7,see ,fig4 #bjh74 ,illu/ration3 ,fig4 #bbe4--;,column> basalt 9 ! neck ( ,k9craig1 ,elie1 se5 f ! we/4 ,illu/ration3 ,fig4 #bbf4--,section across ,l>go ,law4 l l1 ,l[] ,c>bonif]\s /rata2 t1 tuff ( cones2 t'1 tuff ( pla9 beyond ! cones2 ,b ,b1 basalt asc5d+ v5ts & s5d+ out ve9s3 ,b'1 basalt :i* has probably fl[$ out at ! surface4 ,! dott$ l9es are sugge/ive ( ! orig9al outl9e ( ! hill4 7#b7 ,sills4--,9 ! ,clyde coal-field & 9 ! bas9 ( ! ,fir? ( ,=?1 among ! va/ numb] ( sills :i* !re trav]se ! ,c>bonif]\s =mations1 x is possible t "s belong to ! ,p]mian volcanic p]iod 7see vol4 i4 p4 #dgd74 ,:]e ! %eets h be5 intrud$ along horizons t lie bel[ ! upp] /ratigraphical limit ( ! puy eruptions1 !y may n unnaturally be held to belong to ^! manife/ations ( volcanic en]gy1 ?\gh x is obvi\sly q conceivable t "s ( !m may be ( mu* lat] date4 ,b :]e !y lie above ! highe/ plat=ms ( ,c>bonif]\s lavas & tuffs1 !y may be assign$ to a y\ng] volcanic p]iod4 ,we "k z yet ( only two su* p]iods aft] ! deposition ( ! ,c>bonif]\s ,lime/one s]ies 9 ,scotl&--,p]mian & old] ,t]ti>y4 ,unless1 !re=e1 ^! high] sills =m$ "p ( "s o!r display ( subt]ranean activity :i* is n kn[n to h culm9at$ 9 eruptions at ! surface1 !y mu/ be look$ ^u z probably ei!r ,p]mian or ,t]ti>y4 ,9 ! great coal-field ( ,/irl+%ire & ,lan>k%ire1 among ! l>ge sills t break into ! ,mill/one ,grit & ! ,coal-measures1 "o lies entirely 9 ! ,coal-measures1 & cov]s ab\t six squ>e miles ( gr\nd1 /ret*+ f ne> ,cald]cruix ,/ation1 a little ea/ ( ,airdrie1 to ne> ,kirk ( ,%otts1 a di/ance ( ab\t f\r miles4 ,a gr\p ( small] %eets1 possibly connect$ ) ! l>g] mass1 runs = f\r miles fur!r we/ to beyond ,new ,monkl&4 ,ano!r *a9 ( sills1 :i* may also be "p ( ! same great intrusion1 ext5ds f ! ,cant ,hills1 ne> ! ,kirk ( ,%otts1 = m ?an eight miles 9 a nor?-ea/]ly direction4 ,! l>ge/ mass 9 ?is *a9 /ret*es f ,blackridge1 we/ ( ,ba?gate1 = upw>ds ( ?ree miles1 cov]+ an area ( ab\t ?ree squ>e miles & t]m9at+ on ! nor? at ! l9e ( dislocation :i* has be5 foll[$ by "o ( ! ea/ & we/ dykes4 ,ano!r l>ge sill1 :i* appe>s ne>ly two miles fur!r ea/ on ! nor? side ( t dyke1 lies on a l[] /ratigraphical horizon1 = x cuts ! ,c>bonif]\s ,lime/one s]ies1 & does n rea* ! top ( ! ,mill/one ,grit4 ,?is sill is cut ?r\gh by two ( ! lat] dykes4 ,illu/ration3 ,fig4 #bbg4--,ve9 ( :ite-trap cutt+ black c>bonace\s %ales1 a little we/ f ,/4 ,monans ,*ur*4 ,t ^! great intrusions took place lat] ?an ! deposition ( ! ,coal-measures is obvi\s4 ,!re is no satisfactory evid5ce to enable u to decide to :i* ( ! two po/-,c>bonif]\s volcanic p]iods !y may ) mo/ probability be assign$4 ,z "o ( !m is di/9ctly cut by dykes t h be5 ref]r$ to ! ,t]ti>y s]ies1 x might be plausibly argu$ t x at lea/ is ( pre-,t]ti>y date1 & !re=e probably ,p]mian4 ,on ! o!r h&1 z w be %[n 9 a lat] *apt]1 "s portion ( ! sills appe>s to be connect$ ) ! y\ng] or ,t]ti>y dykes4 ,?is problem mu/ = ! pres5t rema9 unsolv$4 ,9 ,ayr%ire :]e1 z already describ$1 basic sills trav]se ! ,p]mian volcanic s]ies1 o!r l>ge intrusive %eets are f\nd ar\nd ! ,p]mian bas94 ,on ! nor? side an important gr\p ( !m1 pass+ ?r\gh ! ,coal-measures into ! ,c>bonif]\s ,lime/one s]ies1 runs f ,troon ea/w>d = m ?an eight miles to beyond ,craigie4 ,on ! s\? side a mu* m ext5sive s]ies may be trac$ f ! ,riv] ,ayr s\?w>ds into ! ,dalmell+ton coal-field1 & !nce nor?-ea/w>ds 9 a wide semicircul> sweep into ! coal-field ( ,new ,cumnock & ,airds ,moss4 ,t "s ( ^! sills proce$ f ! ,p]mian necks has be5 def9itely asc]ta9$1 & ?is fact has be5 already allud$ to 9 connection ) ! v5ts4 ,i h little d\bt t ! great majority1 if n ! :ole1 ( ^! intrusive %eets are to be ref]r$ to ! ,p]mian p]iod4 ,"s ( ! sills mu/ be lat] ?an a "p ( ! ,p]mian volcanic eruptions1 = !y are f\nd 9 at lea/ ?ree places int]calat$ 9 ! zone ( lavas & tuffs4 ,b no in/ance has be5 obs]v$ ( _! trav]s+ ! bas9 ( ,p]mian s&/one :i* ov]lies t zone1 ?\gh a few dykes1 possibly ( ,t]ti>y age1 d cut ?is s&/one4 ,,*apt] ,,xxxii ,,p]mian ,,volcanoes ,,( ,,engl& ,! ,devon%ire ,c5tre--,eruptive ,rocks ( ! ,midl& ,coal-fields4 ,f ! s\? ( ,scotl& we ne$ to pass to ! extreme s\?-we/ ( ,engl& be=e we aga9 enc\nt] a gr\p ( volcanic rocks :i* may be ref]r$ ) "s confid5ce to ! ,p]mian p]iod4 ,an int]e/+ gr\p ( lavas & tuffs has be5 pres]v$ 9 "s ( ! valleys ov] a limit$ area 9 ! ea/ ( ,devon%ire4 ,! ,midl& coal-fields1 h[ev]1 are trav]s$ by a s]ies ( basic eruptive rocks :i* are y\ng] ?an ! ,coal-measures1 & may possibly be ,p]mian4 ,_! mode ( occurr5ce1 & ! argum5ts reg>d+ _! geological age1 w be giv5 9 ! pres5t *apt]4 #a4 ,,devon%ire ,! c\nties ( ,devon & ,cornwall furni% "o ( ! mo/ /rik+ examples to be met ) 9 ,brita9 ( ! p]si/5ce ( volcanic action ov] a limit$ area ?r\gh a long succession ( geological p]iods4 ,! ext5sive eruptions 9 ,devonian "t 7 foll[$ aft] a long int]val by a dim9i%$ s]ies 9 ! ,c>bonif]\s p]iod4 ,b ! subt]ranean en]gy 0 n !n :olly exhau/$1 = x %[$ itself on a feeble scale 9 at lea/ "o limit$ tract ( ! same region dur+ ! ,p]mian p]iod4 ,?us ?r\gh\t ! lat] half ( ,palozoic "t ! extreme s\?-we/ ( ,engl& cont9u$ to be a !atre ( volcanic action4 ,! geological age ( ! igne\s rocks n[ to be ref]r$ to dep5ds ^u ! p>ticul> place 9 ! geological record to :i* we assign ! rem>kable breccias & s&/ones ) :i* !y are associat$4 ,by _m geologi/s :o h be5 unable to recognize any true break 9 ! r$ rocks f _! base up to ! bottom ( ! ,lias1 ^! /rata h be5 gr\p$ z "o great s]ies ref]able to ! ,new ,r$ ,s&/one or ,trias4 ,?is is ! classification adopt$ on ! "o-in* maps ( ! ,geological ,survey4 ,on ! o!r h&1 v>i\s able obs]v]s h po9t$ out ! close resemblance ( ! co>se & f9e breccias at ! bottom ( ! s]ies to recogniz$ ,p]mian deposits 9 ! c5tre ( ,engl& & to p>ts ( ! typical ,ro?lieg5de ( ,g]many4 ,i ne$ only ref] to ! /rongly express$ views ( ,mur*ison1 9 :i*1 z he /at$ 9 8 ,siluria1 he entirely agre$ ) ,conybe>e & ,buckl&1 :o1 aft] a j\rney 9 ,g]many 9 #ahaf1 di/9ctly id5tifi$ ! ,heavytree conglom]ate1 ne> ,exet]1 ) ! ,ro?lieg5de ( ! ,g]mans4#ajd ,9 ! abs5ce ( any fossil evid5ce1 we h only li?ological *>act]s & sequ5ce to guide u1 & ?\gh ! kn[n facts h>dly w>rant a v positive op9ion1 my incl9ation is to reg>d ^! r$ ,devon%ire breccias z probably ,p]mian1 & to foll[ ,mur*ison 9 look+ ^u _! associat$ igne\s masses z furni%+ additional reason = assign+ !m to t p>ticul> geological plat=m4#aje ,footnote #ajd3 ,siluria1 #d? edit4 7#ahfg71 p4 #ccc4 ,see also ,b]g]1 ,trans4 ,geol4 ,soc4 vol4 i4 7#ahaa71 pp4 #ih-ajb2 ,conybe>e & ,phillips1 ,geology ( ,engl& & ,wales1 p4 #cac1 footnote2 ,de la ,be*e1 ,report on ! ,geology ( ,cornwall1 ,devon & ,we/ ,som]set 7#ahci71 *ap4 vii4 p4 #aic4 ,messrs4 ,hull & ,irv+ 7,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlviii4 #ahib1 pp4 #fj1 #fh7 h m rec5tly discuss$ ! subject1 & foll[ ! view ( ,mur*ison4 ,footnote #aje3 ,mur*ison cog5tly argu$ t z no signs ( volcanic activity 7 kn[n 9 ! ,trias1 b 7 abundant 9 ! ,p]mian sy/em1 ! ,devon%ire rocks might be reg>d$ z app]ta9+ to ! old] s]ies1 op4 cit4 ,triassic volcanic rocks1 h[ev]1 are n[ well kn[n on ! ,cont95t4 ,no prop] acc\nt has yet be5 writt5 ( ! volcanic gr\p :i* ,i n[ propose to describe4#ajf ,de la ,be*e 01 ,i ?9k1 ! fir/ to recognize ! true volcanic nature ( ! rocks & _! contemporane\s int]/ratification 9 ! r$ s&/one s]ies4#ajg ,z trac$ by him on ! ,geological ,survey maps1 ^! rocks lie at or ne> ! base ( ! r$ s$im5t>y deposits1 re/+ sometimes directly on ! ,culm-measures1 sometimes on an int]v5+ lay] ( r$ /rata4 ,he f\nd !m 9 ?ree sep>ate di/ricts 9 ! neighb\rhood ( ,exet]1 ! mo/ nor!rly ly+ ne> ,tiv]ton1 ! c5tral ext5d+ f ,kell]ton = a few miles up ! ,yeo ,valley1 beyond ,cr$iton1 & ! ?ird /ret*+ f ! ,city ( ,exet] to ,p5 ,hill1 ab\t five miles to ! s\?-we/4 ,he recogniz$ ! amygdaloids z slaggy lavas1 & saw t ! volcanic breccias & tuffs are int]leav$ ) ! s&/ones4 ,) reg>d to ! probable v5ts f :i* ^! mat]ials 7 eject$1 he ?\ght t ! *ief c5tre ( activity lay at ,kell]ton ,p>k1 :ile 9 o!r localities he believ$ ! bosses ( igne\s rock to desc5d 9 mass d[nw>ds1 z if fill+ up "s crat] or fissure ?r\gh :i* ^! rocks _h be5 vomit$4#ajh ,he speaks also ( qu>tzif]\s porphyries occurr+ among !m1 a /atem5t :i*1 if petrographically accurate1 w\ld sugge/ ! uprise ( a lat] m acid lava 9 "s ( ! v5ts4 ,footnote #ajf3 ,an outl9e ( "s ( _! *>act]s w be f\nd 9 a pap] by ,mr4 ,w4 ,vic>y 9 ,trans4 ,devon%ire ,assoc4 #ahfe1 vol4 i4 "p iv4 p4 #dc4 ,footnote #ajg3 ,see 8 ,report cit$ 9 ! note above4 ,de la ,be*e quotes ,j4 ,j4 ,conybe>e z po9t+ out ! intimate connection ( ^! igne\s & /ratifi$ rocks 7,annals ( ,philosophy1 #bnd s]ies1 vol4 ii4 7#ahba7 p4 #afe72 b ?is au?or wrote at ! "t ( ! ,plutoni/ & ,neptuni/ controv]sy1 & does n commit himself to any di/9ct expression ( op9ion on ! subject4 ,footnote #ajh3 ,report1 p4 #bja4 ,m rec5tly ! gr\nd has be5 revis$ by ,mr4 ,w4 ,a4 ,e4 ,us%] ( ! ,geological ,survey1 :o has asc]ta9$ t ! volcanic rocks appe> 9 _m m places ?an ^? :]e !y 7 not$ on ! old] maps1 & likewise ext5d = "s miles fur!r to ! nor? & we/4 ,x n[ appe>s t 9 ! c5tral & *ief di/rict ! lavas c be foll[$ we/w>d f ,spray ,d[n ne> ,kell]ton to ,gre5slade ne> ,nor? ,tawton1 a di/ance ( ab\t tw5ty-"o miles4 ,_! mo/ nor!rly outcrop is at ,?orn above ,loxb]e 9 ! ,tiv]ton di/rict1 & _! mo/ s\!rly visible portion passes "u ! ,cretace\s rocks ( ,p5 ,hill4 ,! di/ance betwe5 ^! extreme po9ts is likewise ab\t tw5ty-"o miles4 ,! :ole display ( volcanic ph5om5a is compris$ )9 an area ( less ?an #djj squ>e miles4 ,"o ( ! mo/ obvi\s features 9 ?is volcanic tract is ! way 9 :i* ! erupt$ mat]ials lie along ! l9es ( holl[ or valley 9 :i* ! r$ rocks 7 deposit$4 ,?is is mo/ di/9ctly exhibit$ 9 ! c5tral di/rict4 ,"h a belt ( breccias & s&/ones1 v>y+ f "o to ?ree & a half miles 9 bread?1 runs = ab\t five & tw5ty miles we/w>d 9 a depression ( ! ,culm-measures4 ,at int]vals1 ! lavas :i* lie ne> ! base ( ! r$ rocks crop out along ! m>g9 ( ! belt ?r\gh\t mo/ ( its ext5t4 ,b !y d n spread out ov] ! old] rocks1 & !y h evid5tly be5 erupt$ f orifices situat$ along ! l9e ( ! valley4 ,x is ano!r example ( ! relation betwe5 ! tr5d ( holl[s & ! outbreak ( volcanic v5ts1 :i* ,i h ref]r$ to z s /rik+ly display$ 9 ! di/ribution ( ! ,p]mian volcanic rocks ( s\?-we/]n ,scotl&4 ,! volcanic mat]ials ( ! ,devon%ire ,p]mian di/rict consi/ ma9ly ( lavas1 b include also r$ s&y & gravelly tuffs4 ,! :ole volcanic gr\p is rem>kably ?91 nev] atta9+ ev5 ! limit$ developm5t ( ! ,ayr%ire s]ies4 ,no adequate petrographical inve/igation ( ^! rocks has yet be5 made4 ,ext]nally1 z se5 9 ! qu>ries & lanes1 ! lavas pres5t ! close/ resemblance to ^? ( ! ,p]mian bas9s ( ,ayr%ire & ,ni?sdale4 ,!y %[ consid]able diff]5ces ( texture ev5 )9 ! same mass1 "s portions be+ dull1 f9e-gra9$ purpli%-r$ rocks1 ) scatt]$ pseudomorphs ( hmatite & a few porphyritic felsp>s1 o!r p>ts pass+ into an exce$+ly co>se amygdaloid or slaggy pumice4 ,dr4 ,hat*1 aft] a microscopical exam9ation ( a small collection ( specim5s1 f\nd t :ile mo/ are oliv9e-basalts1 conta9+ f]rug9\s pseudomorphs aft] oliv9e 7,raddon ,c\rt1 ,pocombe1 & ne> ,budlake71 o!rs are true &esites 7,ide1 ,kell]ton ,p>k7 & ev5 mica-tra*ytes 7,copple/one1 ne> ,kn[le ,hill74#aji ,z already rem>k$1 "s ( ! old] writ]s m5tion ! exi/5ce ( qu>tz-porphyries4#aaj ,footnote #aji3 ,geol4 ,mag4 #ahib1 p4 #bej4 ,! rocks h be5 m rec5tly describ$ by ,mr4 ,b4 ,hobson1 ,qu>t4 ,j\r4 ,geol4 ,soc4 vol4 xlviii4 7#ahib71 p4 #ejb4 ,! rock ( ,kell]ton ,p>k is call$ by ,mr4 ,hobson mica-augite-&esite1 & he gives a *emical analysis ( x by ,mr4 ,e4 ,hawor?1 op4 cit4 p4 #ejg4 ,mr4 ,watts has lately f\nd "o ( ! or?oclase rocks to be ri* 9 oliv9e4 ,footnote #aaj3 ,see ,de la ,be*e1 ,report1 pp4 #bjc1 #bjd4 ,my colleague1 ,mr4 ,us%]1 f\nd close to ! ,?urle/one outli] ( conglom]ate ne> ,k+sbridge1 ,devon%ire1 a small boss ( qu>tz-porphyry :i* rises ?r\gh & alt]s ! ,devonian rocks4 ,! actual junction ( ?is mass ) ! conglom]ate is n se51 nor h any fragm5ts ( ! porphyry be5 notic$ among ! pebbles4 ,mr4 ,us%] in=ms me t 9 ! qu>ry ! visible exposure ( ! acid rock is surr\nd$ an cov]$ by mica-porphyrite1 probably &esite4 ,! geographical conditions 9 :i* ! r$ rocks ( ,devon%ire accumulat$ 7 ^? s *>act]i/ic ( ! ,p]mian & ,trias =mations ?r\gh\t ,brita94 ,! r$ s&/ones & s&y m>ls ga!r$ 9 inl& bas9s1 :]e ! wat] seems to h become too sal9e & bitt] to support animal life4 ,! /rata are consequ5tly s+ul>ly devoid ( organic rema9s4 ,! climate 0 probably arid1 & ! abs5ce or sc>city ( traces ( t]re/rial vegetation indicates t ! l& ar\nd ! wat]-bas9s /ret*$ 9 wide s&y & rocky wa/es4 ,9 ! dry atmosph]e & "u ! influ5ce ( rapid radiation ! cliffs & crags ( ,culm-measures w\ld dis9tegrate into angul> rubbi%1 & ?is mat]ial1 slipp+ into ! lakes or wa%$ d[n by occasional ra9-/orms1 =ms n[ ! breccias t con/itute s typical a feature 9 ! ,p]mian sy/em4 ,illu/ration3 ,fig4 #bbh4--,section at ,belv$]e1 ,s4,w4 ( ,exet]4 a1 ,culm-measures2 b1 breccia & m>ls2 c1 lavas2 d1 r$ pebbly s&/ones4 ,illu/ration3 ,fig4 #bbi4--;,diagram to %[ ! uncon=mability & ov]lap ( ! ,p]mian rocks 9 ! ,cr$iton ,valley4 a1 ,culm-measures2 b1 breccias & s&/ones2 c1 lava-gr\p2 d1 breccias ) fragm5ts ( lava pass+ up into s&/ones & m>ls 7e74 ,x 0 :ile ?is geographical type cont9u$ 9 ! ,s\?-we/ ( ,engl& t ! volcanic eruptions took place :i* we are n[ consid]+4 ,de la ,be*e correctly ref]r$ ^! eruptions to ! e>ly "p ( ! r$ s&/one s]ies4 ,a brief exam9ation ( ! gr\nd suffices to %[ t al?\gh1 z he po9t$ out1 ! volcanic rocks lie t[>ds ! base ( t s]ies1 z %[n 9 ,fig4 #bbh1 !y d n all occupy ! same plat=m4 ,t 9 "s cases ! lavas lie directly on ! ,culm-measures1 :ile 9 o!rs !y are sep>at$ f ^! /rata by #ajj feet or m ( r$ s&/ones & breccias 7,fig4 #bbi71 w\ld n 9 itself be pro( ( any diff]5ce ( age or /ratigraphical position 9 ! igne\s rocks1 = ! floor on :i* ! ,p]mian =mations 7 "h laid d[n c be %[n to h be5 s+ul>ly unev54 ,prom95t hills ( ,culm grit1 sev]al hundr$ feet high1 rose above ! bas9s 9 :i* ! e>lie/ ,p]mian s$im5ts 7 deposit$1 & ^! em95ces 7 gradually subm]g$ & buri$ "u ! detritus4 ,b t ! volcanic zone includes 9 "s places m ?an "o outfl[ ( lava ) lay]s ( s&/one1 breccia & tuff betwe5 ! successive %eets may be prov$ 9 diff]5t p>ts ( ! di/rict4 ,?us ! two conspicu\s hills at ,kell]ton are compos$ ( sev]al %eets ( highly slaggy lava1 sep>at$ by breccia1 & a ?ird mu* ?9n] %eet lies above ^!1 int]calat$ 9 a mass ( breccia1 s&/one & s&y tuff 7,fig4 #bcj74 ,aga91 at ,budlake ! s&/ones & f9e breccias include a ?9 b& ( vesicul> lava1 :ile f>!r to ! ea/ !y are int]rupt$ by a high] & ?ick] zone ( simil> mat]ial4 ,illu/ration3 ,nor? ,hill ,s\? ,hill ,fig4 #bcj4--,section ( ! volcanic s]ies at ,kell]ton1 ,devon%ire4 a1 ,breccias & s&/ones2 b1 lavas4 ,^! igne\s %eets c be %[n by _m int]e/+ sections to h be5 p\r$ out contemporane\sly ) ! deposit ( ! s$im5t>y mat]ial among :i* !y occur4 ,at ,crabtree1 = in/ance1 ne> ,kell]ton1 ! upp]mo/ lava is a ?9 %eet ( highly slaggy texture1 :i* re/s imm$iately on ! gravelly r$ s&/one & cat*es up p>ts ( x1 :ile ! pebbles include fragm5ts ( "s ( ! &esites bel[4 ,! d>k lavas are occasionally trav]s$ by ve9s ( f9e h>d s&/one1 :i* desc5d+ f above1 l ^? 9 ! ,old ,r$ ,s&/one & ,p]mian lavas ( ,scotl&1 h be5 produc$ by ! silt+ or drift+ ( f9e s& into cracks 9 ! lava1 be=e ! igne\s mat]ial 0 entirely buri$4 ,^! features are well expos$ 9 ! high ridge ( ! ,belv$]e ne> ,exet] 7,fig4 #bbh71 :]e1 ov] a ?9 & incon/ant b& ( r$ breccia & m>l :i* re/s on ! upturn$ ends ( ! ,culm-measures1 a b& ( dull-r$ &esite may be se54 ,?is rock1 p>tly compact & p>tly highly amygdaloidal1 is 9 "s portions full ( irregul> fissures & cavities fill$ ) s&/one4 ,n[h]e among ! ,palozoic volcanic rocks ( ,brita9 are m rem>kable examples ( ! slaggy /ructure to be f\nd ?an 9 ^! ,devon%ire lavas ( probably ,p]mian age4 ,i w\ld especially cite ! rock ( ,kn[le ,f>m1 a few miles to ! we/ ( ,cr$iton1 z 9 "p a m]e spongy pumice1 blocks ( :i* w\ld orig9ally h float$ 9 wat]4 ,"o ( ! be/ sections 9 ! di/rict = ! exemplification ( ! int]nal /ructures ( ^! lavas is t 9 ! l>ge qu>ry at ! top ( ,posbury ,hill4 ,on ! we/ side ( ?is qu>ry ! rock is tol]ably compact1 b conta9s vesicles & irregul> /eam-holes4 ,on ! ea/ side x passes upw>d & lat]ally into a co>se agglom]ate ( its own fragm5ts1 & 9 its mass x encloses simil> agglom]ate4 ,no %>p passage c be trac$ betwe5 ! two rocks4 ,s f> z ,i c\ld judge1 x seem$ to me t ! lava _h brok5 up z x mov$ along1 possibly %att]$ by com+ 9 contact ) wat]4 ,! agglom]ate is ov]la9 by "s r$di% a%y s&/one1 :i* fills up ! int]/ices betwe5 ! slags1 & is imm$iately cov]$ by a b$ ( lilac &esite1 m>k+ ano!r di/9ct outfl[4 ,illu/ration3 ,fig4 #bca4--,section ( agglom]ate ov]la9 ) s&/one & &esite1 ,posbury1 ,cr$iton4 ,z 9 ,ayr%ire1 ! lavas ( ,devon%ire are n accompani$ by any ?ick accumulation ( tuff4 ,! fragm5t>y dis*>ges consi/$ 9 bo? areas ( f9e du/ & gravelly detritus ( small lapilli1 :i* 7 n eject$ 9 su* quantities z entirely to conceal ! ord9>y non-volcanic s$im5t ( ! wat]-bas94 ,! du/ & c9d]s m+l$ ) ! r$ s& & angul> scree-mat]ial1 s t we n[ see a gr\p ( r$1 some:at a%y s&/ones & breccias4 ,among ! compon5t fragm5ts ( ! breccias1 a consid]able v>iety ( igne\s mat]ial may be obs]v$4 ,:ile ! mo/ ( ! non-volcanic /ones may h be5 d]iv$ by ord9>y processes ( wea!r+ f rocks expos$ at ! surface1 x is by no means improbable t "s ( !m1 includ+ ev5 pieces ( ,culm grit1 killas & bak$ slate1 may h be5 eject$ f volcanic v5ts4#aaa ,footnote #aaa3 ,on ! composition ( ! ,devon%ire breccias see ,mr4 ,r4 ,n4 ,wor?1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlvi4 7#ahij71 p4 #fi4 ,?is au?or has adopt$ ! view t ! granite ( ,d>tmoor repres5ts ! neck ( a great volcano f :i* ^! lat] volcanic mat]ials 7 eject$4 ,b all ! evid5ce seems to me 9 fav\r ( num]\s small v5ts situat$ n f> f ! outcrops ( ! lavas1 z /at$ 9 ! text4 ,see ,mr4 ,b4 ,hobson1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlviii4 7#ahib71 p4 #dih4 ,! ,d>tmoor granite is lat] ?an ! surr\nd+ ,c>bonif]\s rocks1 b no good evid5ce has be5 obta9$ to connect x ) ! ,p]mian volcanic ph5om5a ( ,devon%ire4 ,tak+ ! volcanic rocks ( ?is di/rict z a :ole1 ,i reg>d !m z ! m]e edges ( %eets t h fl[$ f v5ts :i* n improbably lie conceal$ some:]e along ! c5tres ( ^! old ,p]mian valleys4 ,no visible necks h be5 describ$ f any "p ( ! area1 & ?\gh ,i h n exam9$ ! :ole ( x1 no?+ ( t nature 0 detect$ by me ei!r 9 ! ,cr$iton ,valley or betwe5 ,silv]ton & ! ,exet] neighb\rhood4 ,! ,tiv]ton di/rict1 :i* has n yet be5 se>*$1 appe>s to be ! only tract :]e any *ance rema9s ( f9d+ "s ( ! v5ts4 ,no indication ( any sills has be5 met ) among ! ,devon%ire ,p]mian rocks4 ,none ( ! lavas :i* ,i h se5 h ! int]nal *>act]s ( true sills1 :ile 9 ! field _! association ) ! s&/ones & breccias 9 no obs]v$ case po9ts to intrusion4 ,?\gh mu* rema9s to be done 9 ?is region be=e an adequate acc\nt c be giv5 ( ! int]e/+ s]ies ( eruptions :i* concludes ! long volcanic hi/ory ( ! ,s\?-we/ ( ,engl&1 en\gh is kn[n to indicate ! g5]al "* ( ! ph5om5a4 ,! eruptions 7 on ev5 a feebl] scale ?an ^? ( ! ,p]mian p]iod 9 ,scotl&1 b !y seem to h resembl$ !m 9 _! g5]al "*4 ,small puy-l v5ts 7 op5$1 f :i* d>k scoriace\s lavas & %[]s ( gravelly tuff & /ones 7 dis*>g$ ov] ! floor ( ! inl& sea or lake-bas9 9 :i* ! r$ s&/ones & breccias 7 accumulat$4 ,^! outfl[s & explosions took place too1 z 9 ,scotl&1 t[>ds ! beg9n+ ( ! deposition ( ! r$ /rata1 & entirely ceas$ long be=e t deposition came to an end4 ,9 ea* area ! eruptions m>k ! close ( ,palozoic volcanic activity 9 ,brita94 ,! v>i$ & recurr5t volcanic episodes :i* di/+ui%$ ea* successive geological p]iod f ! ,ar*an onw>ds n[ def9itely t]m9ate1 n to be resum$ until aft] ! pass+ ( ! :ole ( ! va/ cycle ( ,mesozoic ages4 #b4 ,,eruptive ,,rocks ,,9 ,,! ,,midl& ,,coal-,,fields ,betwe5 ! ?ick & ?or\ghly m>9e developm5t ( ! ,c>bonif]\s ,lime/one 9 ,d]by%ire & 9 ,s\? ,wales1 !re lies ! region1 already ref]r$ to1 :]e9 bo? ! ,c>bonif]\s ,lime/one & ,mill/one ,grit die out aga9/ :at mu/ h be5 a ridge ( l& or gr\p ( isl&s t /ret*$ 9 a g5]al ea/ & we/ direction f ! high gr\nds ( ,wales ?r\gh ,%rop%ire1 ,/af=d%ire & ,leice/]%ire4 ,on ! slopes ( ?is ridge ! lime/one is gradually ov]lapp$ by ! ,mill/one ,grit1 & bo? are 9 turn ov]lapp$ by ! ,coal-measures1 :i* are !n f\nd ly+ imm$iately on ! m anci5t rocks ( ! region--,cambrian or pre-,cambrian1 ,silurian & ,old ,r$ ,s&/one4 ,! gradual subsid5ce t l$ to ! deposit ( sev]al ?\s& feet ( ,c>bonif]\s /rata ov] ! regions to nor? & s\?1 be=e ! beg9n+ ( ! ,coal-measure p]iod1 does n seem to h s5sibly affect$ ! p]si/5ce ( ?is old t]re/rial surface1 :i* probably lay on an axis ( upw>d movem5t1 s t1 amid/ ! surr\nd+ depression1 its position above wat] 0 on ! :ole ma9ta9$4 ,b !re are indications t ! inequality ( movem5t 9 ?is "p ( ! e>?'s cru/ 0 ( mu* old] date ?an ! ,c>bonif]\s p]iod4 ,! ,old ,r$ ,s&/one is con=mably cont9u\s bel[ ! base ( ! ,c>bonif]\s sy/em1 & 9 ,wales is e/imat$ to be "s #aj1jjj feet ?ick4 ,no break has yet be5 detect$ 9 ?is va/ accumulation ( s$im5t>y mat]ial1 ?\gh x is highly probable t "s su* uncon=mability mu/ exi/ 9 x z t betwe5 ! ,scotti% ,l[] ,old ,r$ ,s&/one1 :i* passes d[n into ! ,upp] ,silurian %ales1 & ,upp] ,old ,r$ ,s&/one1 :i* graduates upw>d into ! base ( ! ,c>bonif]\s =mations4 ,b ev5 if su* a break %\ld be discov]$1 x w n acc\nt = ! position ( ! ,coal-measures on ,cambrian or ev5 p]haps old] rocks4 ,x is h>dly conceivable t1 _h ^! rocks be5 cov]$ ) a full developm5t ( ,old ,r$ ,s&/one1 !y c\ld h be5 /ripp$ ( x by d5udation be=e ! deposition ( ! ,coal-measures4 ,x seems mu* m probable t ! discrepancy 9 ! t]re/rial movem5ts _h comm5c$ 9 ,old ,r$ ,s&/one "t1 & t ^! ridges ( anci5t ,palozoic rocks nev] sank bel[ ! wat]s 9 :i* ! va/ ?ickness ( r$ s&/ones1 m>ls & conglom]ates 0 laid d[n4#aab ,footnote #aab3 ,see a discussion ( ?is subject 9 ,jukes' ,preface to 8 ,s\? ,/af=d%ire ,coal-field4 ,b ap>t f ! "q ( its antiquity1 ?is tract ( p]si/5t l& has a special int]e/ 9 ! hi/ory ( volcanic action 9 ,brita91 = x 0 ! sc5e ( "s rem>kable protrusions ( eruptive mat]ial :i* took place aft] a "p1 & possibly aft] ! :ole1 ( ! ,coal-measures 7 accumulat$4 ,! date ( ^! protrusions _c be fix$ ) great] precision2 b !re c be no d\bt t !y belong to "o ( ! lat] volcanic p]iods 9 ! geological hi/ory ( ,brita91 & ! acc\nt ( !m is !re=e includ$ 9 ! pres5t ,*apt] ( ?is "w4 ,9 ! ,engli% ,midl&s s\? ( ,/af=d1 ov] a tract ( c\ntry ab\t #gjj squ>e miles 9 ext5t1 /ret*+ f ,birm+ham on ! ea/1 across ! vale ( ! ,sev]n1 to ! upl&s ( ,%rop%ire on ! we/1 ! ,coal-measures1 p>tly isolat$ into outli]s by d5udation & p>tly sep>at$ by ov]ly+ y\ng] =mations1 are pi]c$ by masses ( intrusive igne\s rocks4 ,_m ( ^! masses h long be5 famili> to geologi/s4 ,^?1 = example1 ( ! ,clee ,hills ( ,%rop%ire1 & ! ,r[ley1 ,b>r[ & ,p\k ,hills ( ,/af=d%ire & ,worce/]%ire1 h be5 frequ5tly describ$1 _! relations to ! surr\nd+ /rata h be5 m9utely s\ght out1 _! composition has be5 *emically det]m9$1 & _! microscopic /ructure has be5 inve/igat$4 ,b !y h be5 /udi$ r z individual masses ( local importance4 ,no attempt has yet be5 made to asc]ta9 h[ f> !y are capable ( be+ gr\p$ toge!r z "o connect$ s]ies1 l9k$ ) ea* o!r 9 *emical & m9]alogical *>act]s1 & conta9+ a def9ite record 9 ! volcanic hi/ory ( ! c\ntry4 ,?is is a task :i*1 x is to be hop$1 "s compet5t inquir] w be=e long und]take4 ,9 ! meantime x is only possible to review "h ! already publi%$ in=mation1 & to ga!r f x :at may at pres5t be surmis$ to h be5 ! hi/ory ( ^! lat] eruptions ( ! ,midl&s4 ,! areas :]e ! igne\s rocks n[ to be describ$ are exhibit$ may be conv5i5tly plac$ 9 ! foll[+ five gr\ps3--#a/1 ,titt]/one ,clee ,hill2 #bnd1 ,br[n ,clee ,hill2 #crd1 ,! ,=e/ ( ,wyre ,coal-field2 #d?1 ,! ,coalbrookdale ,coal-field2 & #e?1 ,! ,s\? ,/af=d%ire ,coal-field4 #a4 ,! ,titt]/one ,clee ,hill =ms a ridge ab\t sev5 miles long & a mile & a qu>t] broad1 runn+ 9 a nor?-ea/]ly direction ov] ! ,old ,r$ ,s&/one upl&s ( ! s\? ( ,%rop%ire4 ,! gr\nd rises gradually t[>ds ! s\?-we/1 until x rea*es !re a height ( #aged feet 7,fig4 #bcb74 ,on ! nor?-we/]n side ( ! ridge1 ! la/ vani%+ repres5tative ( ! ,c>bonif]\s ,lime/one c be se5 to be ov]lapp$ ! ,mill/one ,grit1 :i*1 z x is trac$ t[>ds ! s\?-we/1 is 9 turn ov]lapp$ by ! ,coal-measures1 & ^!1 ab\t #djj feet ?ick1 !n re/ imm$iately on ! ,old ,r$ ,s&/one4 ,two %eets ( column> oliv9e-dol]ite1 possibly orig9ally connect$1 lie z cakes on ! summit & ea/]n slope ( ! ridge1 & cov] 9 all a space ( ab\t a squ>e mile & a half4 ,! l>g] %eet1 :i* v>ies f #fj to #ahj feet 9 ?ickness1 ov]lies ! ,coal-measures1 & ! coals ( ! ,cornbrook coal-field h be5 work$ und]nea? x4 ,! small] mass1 :i* may be #cjj feet 9 ?ickness1 =ms ! summit ( ! ridge4 ,on its ea/]n side x reposes on ,coal-measures1 :i* are !re mu* di/urb$2 b on ! we/ side1 :]e x =ms a bold capp+ to ! esc>pm5t1 x is und]la9 at once by ! ,old ,r$ ,s&/one4 ,!re _c be any d\bt t ^! masses ( eruptive mat]ial are sills1 :i* h be5 inject$ into ! ,c>bonif]\s /rata1 & p>tly betwe5 ^! /rata & ! ,old ,r$ ,s&/one4 ,"o or m dykes ( eruptive rock h be5 met ) 9 m9+1 & ! coal on approa*+ !m und]goes alt]ation4#aac ,footnote #aac3 ,see ,j4 ,r4 ,wright1 ,trans4 ,geol4 ,soc4 7#bnd s]47 iii4 7#ahcb71 p4 #dhg4 ,titt]/one ,clee ,hill is %[n on ,%eet #ee ,n4,e4 & ,n4,w4 ( ! ,geological ,survey1 & 9 ,horizontal ,sections1 ,%eets #cc & #cf1 f :i* ,fig4 #bcb is r$uc$4 ,! microscopic /ructure ( ! dol]ite has be5 describ$ by ,mr4 ,allport1 ,geol4 ,mag4 #ahgj1 p4 #aei2 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxx4 7#ahgd71 p4 #eej4 ,illu/ration3 ,fig4 #bcb4--;,diagrammatic section across ,titt]/one ,clee ,hill4 #a4 ,old ,r$ ,s&/one2 #b4 ,c>bonif]\s ,lime/one2 #c4 ,mill/one ,grit2 #d4 ,coal-measures2 #e #e4 ,column> oliv9e-dol]ite4 #b4 ,br[n ,clee ,hill consi/s ( two outli]s ( ,coal-measures1 ea* ab\t a mile long1 plac$ on ! summit ( a broad ridge ( ,old ,r$ ,s&/one1 & ris+ to a height ( #ahjj feet above ! sea4 ,bo? ( ! outli]s is capp$ ) a cake ( dol]ite1 & a ?ird small] pat* ( ! same mat]ial lies on ! s\!rn outli] betwe5 ! capp+s4 ,nei!r at ?is locality nor ar\nd ,titt]/one ,clee h any eruptive rocks be5 obs]v$ ris+ ?r\gh ! old] /rata4 ,x is evid5t t 9 bo? cases ! orifices or fissures up :i* ! molt5 mat]ial rose lie conceal$ "u ! surviv+ cakes ( dol]ite4#aad ,footnote #aad3 ,br[n ,clee ,hill is mapp$ 9 ,%eet #fa ,s4,w4 ( ! ,geological ,survey1 & its /ructure is %[n 9 ,%eet #cf ( ! ,horizontal ,sections4 #c4 ,=e/ ( ,wyre ,coal-field4--,on bo? sides ( ?is ext5sive tract ( ,coal-measures1 ! /rata ne> ! base ( ! s]ies are trav]s$ by sills or dykes ( oliv9e-dol]ite l t ( ! ,clee ,hills4 ,! s&/ones 9 contact ) ! eruptive rock h be5 indurat$4 ,9 ?is di/rict1 also1 ! evid5ce %[s t ! %eets are intrusive1 & lat] ?an ! portion ( ! ,coal-measures !re visible4#aae ,footnote #aae3 ,?is di/rict is repres5t$ 9 ,%eets #ee ,n4,e4 & #fa ,s4,e4 ( ! ,geological ,survey4 ,! microscopic /ructure ( ! l>g] mass on ! we/ side ( ! coal-field1 & ! v>iations 9 ! m9ute /ructure ( ! intrusion :i* =ms a long ridge on ! ea/ side1 are describ$ by ,mr4 ,allport1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxx4 pp4 #eej1 #eea4 #d4 ,coalbrookdale ,coal-field4--,9 ?is int]e/+ di/rict a sill ( r f9ely cry/all9e oliv9e-dol]ite1 :i* is e/imat$ to be ne>ly #bjj feet ?ick1 is traceable f ne> ,little ,w5lock = ?ree miles to ! nor?1 int]calat$ betwe5 ! ,c>bonif]\s ,lime/one & ! ,silurian rocks und]nea?4 ,x appe>s to und]lie ! we/]n "p ( ! ,coal-field1 = x is expos$ by d5udation 9 sev]al valleys betwe5 ,little ,w5lock & ,great ,dawley4 ,ow+ to ! ?9n+ out ( ! ,c>bonif]\s ,lime/one 9 an ea/]ly direction1 ! sill gradually comes to h ! ,mill/one ,grit on its upp] surface1 & at "o po9t is repres5t$ on ! ,geological ,survey map z ev5 intrud$ into ! ,coal-measures4 ,"h aga9 we h an intrusive %eet ( lat] date ?an at lea/ ! e>li] "p ( ! ,coal-measures1 & no evid5ce ( any sup]ficial outfl[ ( volcanic mat]ial4#aaf ,footnote #aaf3 ,! ,coalbrookdale coal-field has be5 describ$ by ,sir ,joseph ,pre/wi*1 ,trans4 ,geol4 ,soc4 7#b7 v4 p4 #dbh2 & ,pr(4 ,e4 ,hull1 ,qu>t4 ,j\r4 ,geol4 ,soc4 xxxiii4 7#ahgg71 p4 #fbi4 ,! m9ute /ructure ( ! sill at ,little ,w5lock is ref]r$ to by ,mr4 ,allport1 op4 cit4 p4 #eej4 ,! gr\nd is mapp$ on ,%eet #fa ,n4,e4 ( ! ,geological ,survey1 & its /ructure is %[n on ,%eet #ed ( ! ,horizontal ,sections4 #e4 ,s\? ,/af=d%ire ,coal-field4--,?is di/rict1 9 respect to its igne\s int]calations1 has be5 mu* m fully exam9$ & describ$ ?an any ( ! o!rs4 ,x =ms ! subject ( an exce$+ly able memoir by ,jukes1 :o c>efully /udi$ its geology & del9eat$ x on ! maps & sections ( ! ,geological ,survey4 ,s9ce 8 "t ! rocks h be5 /udi$ microscopically1 b no mat]ial facts reg>d+ ! /ratigraphy h be5 obta9$ 9 addition to ^? :i* he pati5tly collect$ & g5]aliz$ ^u4#aag ,footnote #aag3 ,jukes1 ,s\? ,/af=d%ire ,coal-field1 ,mem4 ,geol4 ,surv4 #bnd edit4 7#ahei74 ,! area is embrac$ 9 ,%eet #fb ,n4,w4 & ,s4,w4 ( ! ,geological ,survey1 & is illu/rat$ 9 ,%eets #bc1 #bd & #be ( ! ,horizontal ,sections4 ,?is coal-field is above #bj miles long & #e miles broad4 ,its /rata re/ uncon=mably on ,upp] ,silurian /rata1 :i*1 z "p ( ! anci5t ridge or isl& already ref]r$ to1 project "h & !re f amid/ ! ,coal-measures4 ,! b\nd>ies ( ! field on ! ea/ & we/ sides are *iefly made by faults :i* br+ d[n ,p]mian & ,triassic =mations aga9/ ! ,c>bonif]\s /rata4 ,?r\gh\t ?is coal-field %eets ( igne\s rock are abundant4 ,9 ! detail$ acc\nt ( !m giv5 by ,jukes 9 8 admirable essay on ! ,s\? ,/af=d%ire ,coal-field1#aah he di/+ui%$ two k9ds ( igne\s mat]ial--basalt1 :i* comes out at ! surface1 & sometimes ov]lies ! ,coal-measures 9 l>ge cakes l t ( ! ,r[ley ,hills1 :i* ext5ds = two miles 9 "o direction & m ?an a mile 9 ano!r2 & gre5/one1 :i* burr[s among ! coal-be>+ /rata1 & gives (f dykes & ve9s ( :ite rock-trap4 ,!re does n appe>1 h[ev]1 to be any ess5tial diff]5ce 9 composition1 age or orig9 betwe5 ^! contra/$ k9ds ( igne\s mat]ial4 ,!y n improbably all belong to "o s]ies ( extrusions1 _! di/9ctions be+ due r to ! conditions "u :i* !y 7 erupt$1 & 9 p>ticul> to _! comp>ative ?ickness1 & ! influ5ce ( adjac5t coals & c>bonace\s %ales ^u !m4 ,footnote #aah3 ,op4 cit4 p4 #aag4 ,! igne\s rocks se5 at ! surface 9 ?is di/rict =m a s]ies ( well-m>k$ em95ces4 ,( ^! ! l>ge/ ext5ds z a ridge f ,dudley to beyond ,r[ley ,regis1 a di/ance ( m ?an two miles4 ,to ! we/ ( ?is tract1 a numb] ( small pat*es ( ! same mat]ial crop out at ! surface1 ! mo/ important =m+ ,b>r[ ,hill4 ,six miles f>!r nor? ano!r gr\p ( simil> pat*es may be se54 ,( ^! ! l>ge/ occurs at ,w$nesfield1 b ! mo/ not$ =ms ! ,p\k ,hill1 :i* has long be5 not$ = ! beauty ( its column> /ructure4 ,! %eets ( gre5/one met ) 9 ! coal-field are m num]\s & ext5sive ?an ! deta*$ areas ( m compact rock visible above gr\nd1 a s+le %eet be+ sometimes traceable 9 ! coal-work+s = two miles 9 "o direction4 ,! eruptive rocks ( ?is di/rict1 :5 exam9$ 9 _! fre%e/ =m1 consi/ ( well-pres]v$ oliv9e-dol]ite4 ,an exam9ation ( ! gre5/one & ! :ite rock-trap1 :i* runs 9 f+]s & ?reads ?r\gh ! coal1 %[s t ^! are really ! same dol]ite :i* has und]gone alt]ation1 ! f]rug9\s silicates hav+ especially be5 decompos$4#aai ,footnote #aai3 ,allport1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxx4 7#ahgd71 p4 #edg4 ,*emical analysis also %[s ! id5tity ( ! rocks & ! nature ( ! alt]ation ( ! :ite rock4 ,see ,jukes1 ,s\? ,/af=d%ire ,coal-field1 pp4 #aag1 #aah4 ,! sills ( gre5i% decompos$ mat]ial t h be5 inject$ among/ & alt] ! coals1 v>y f #ae feet to #hj or #ij feet 9 ?ickness4 ,! l>ge/ ( ! dol]ite cakes on ! surface1 t ( ! ,r[ley ,hills1 is some:at irregul> 9 its ?ickness1 b may rea* z mu* z #ajj feet4 ,t ne>ly ! :ole ( ! igne\s mat]ial is intrusive is admitt$ by all obs]v]s :o h /udi$ ! gr\nd4 ,! mann] 9 :i* ! basalts & gre5/ones s5d out ve9s into ! ,coal-measures %[s conclusively t !y h be5 inject$ into ! /rata4 ,! only rock ab\t :i* "s d\bt has be5 express$ is t ( ! ,r[ley ,hills1 :i* ,jukes 0 dispos$1 ?\gh n )\t "s hesitation1 to consid] z "p ( an actual lava-/ream4 ,he bas$ ?is inf]5ce *iefly on ! occurr5ce1 imm$iately "u ! dol]ite1 ( :at he look$ ^u z a trappean breccia or brecciat$ a%1 conta9+ r\nd$ & angul> fragm5ts ( igne\s rock ly+ 9 a br[n r f]rug9\s pa/e1 t looks l ! debris ( a basaltic rock4#abj ,?is breccia he reg>d$ z belong+ to & pass+ into ! ,coal-measures1 & he 0 ?us incl9$ to reg>d ! dol]ite z a lava ( ,coal-measure age4 ,footnote #abj3 ,op4 cit4 p4 #aai4 ,x is possible1 h[ev]1 t ! trappean breccia may be ( ! same nature z ! uncompress$ balls ( basalt b$d$ 9 a mass ( decompos$ basalt or basaltic 'wacke' or clay#aba--t is1 a decay$ contact lay] ( ! eruptive rock4 ,b if x be reg>d$ z ! fragm5tal accompanim5t ( a lava-/ream1 x c h>dly belong to ! ,coal-measures4 ,if ! dol]ite _h be5 a lava ( t age1 x ought to be f\nd ly+ con=mably on ! ,coal-measures4 ,b ?is x does n appe> to d4 ,mak+ e all[ance = ! way 9 :i* an advanc+ curr5t ( lava might pl\gh up s(t s$im5t on ! bottom ( ! sea or ( a lake1 we c h>dly ?us acc\nt = ! v unev5 surface ( ,coal-measures on :i* ! %eet ( igne\s rock re/s4 ,if ! ,r[ley rock be look$ ^u z a lava :i* fl[$ out at ! surface1 x mu/1 ,i ?9k1 be assign$ to a "t subsequ5t to t ( ! ,coal-measures1 :5 ^! /rata _h be5 uprais$ & _h suff]$ "s am\nt ( d5udation4 ,i confess1 h[ev]1 t ! petrographical *>act]s ( ! rock1 ! alt]ation ( ! coals :i* h be5 work$ und]nea? x1 & ! abundant ve9s ( :ite rock :i* !re trav]se ! seams1 induce me to reg>d ?is rock z =m+ no exception to ! g5]al rule 9 ! ,midl&s1 b z hav+ be5 intrud$ z a sill1 n[ laid b>e by d5udation4 ,its fre%] condition may arise f its ?ickness1 or f "s o!r circum/ance :i* has n be5 asc]ta9$4 ,footnote #aba3 ,op4 cit4 p4 #abf4 ,we h n[ to consid] ! probable geological date ( ! v>i\s intrusions ( basic igne\s mat]ial :i* c be trac$ ov] s wide an area 9 ! c5tre ( ,engl&4 ,9 discuss+ ! subject1 ,jukes po9t$ out t 9 ! surr\nd+ di/rict no igne\s rocks ( any k9d are f\nd 9 any =mation new] ?an ! ,coal-measures4#abb ,?is /atem5t is1 ) ! exception ( "o locality1 und\bt$ly true4#abc ,b on any view !re mu/ h be5 a long int]val ( "t betwe5 ! =mation ( ! highe/ /rata ( ! ,s\? ,/af=d%ire coal-field & t ( ! l[e/ ,p]mian deposits ( ! di/rict4 ,x is q conceivable1 ?\gh at pres5t incapable ( pro(1 t ! extravasation ( eruptive mat]ial took place aft] ! close ( ! ,c>bonif]\s p]iod & dur+ ! e>li] "p ( ! ,p]mian p]iod4 ,footnote #abb3 ,op4 cit4 p4 #aca4 ,footnote #abc3 ,see note on next page4 ,jukes fur!r %[s t at :atev] p]iod ^! igne\s rocks 7 produc$1 !y 7 all exi/5t be=e ! production ( ! faults & dislocations t h trav]s$ ! ,coal-measures1 & be=e any great d5udation _h be5 effect$ on ! c\ntry4 ,?is argum5t may be readily grant$4 ,b1 s f> z we "k1 _m1 if n mo/1 ( ! faults trav]se also ! surr\nd+ ,p]mian & ,triassic rocks1 s t igne\s masses protrud$ dur+ ^? p]iods w\ld be affect$ by ! same dislocations4 ,:5 we consid] ! hi/ory ( ,palozoic "t 9 ?is c\ntry1 & especially ! pro(1 obta9able ev]y:]e else 9 ,brita91 t volcanic en]gy became quiesc5t dur+ ! accumulation ( ! ,coal-measures1 we may well dem& bett] evid5ce ?an has hi!rto be5 =?com+ t any portion ( ! dol]ites ( ! ,midl&s is ( ,c>bonif]\s age4 ,x is important to notice t ?\gh ! dol]ite sills & ve9s are s abundant 9 ! ,s\? ,/af=d%ire coal-field1 com+ ev5 9 _m places up to ! pres5t surface ( ! gr\nd1 no s+le case has be5 obs]v$ :]e !y rise into ! ,p]mian rocks t ov]lie ! ,coal-measures uncon=mably4 ,x is difficult to believe t1 _h ^! intrusions tak5 place aft] ! deposition ( ! y\ng] =mation1 !y %\ld n be f\nd p5etrat+ x4#abd ,x seems almo/ c]ta9 t !y mu/ be ( an age int]m$iate betwe5 ! ,coal-measures ( ,s\? ,/af=d%ire & ! surr\nd+ breccias & s&/ones ( ! ,p]mian s]ies4 ,& z !re is cle> evid5ce ( contemporane\s volcanic action 9 ! l[e/ "p ( ! ,p]mian sy/em to ! nor? 9 ,scotl& & to ! s\? 9 ,devon%ire1 ! inf]5ce seems n unreasonable t ^! intrusive basalts ( ! ,midl&s are mo/ probably ( ,p]mian age4 ,footnote #abd3 ,only "o in/ance is kn[n :]e 9 ,/af=d%ire any igne\s rock has be5 intrud$ into rocks y\ng] ?an ! ,coal-measures 7,allport1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xxx4 p4 #eea2 ,%eet #gb ,s4 ,w4 ( ! ,geological ,survey1 & ,horizontal ,sections1 ,%eet #eg74 ,x =ms a dyke :i* has be5 trac$ ne> ,norton ,bridge1 ,sw9n]ton & ,butt]ton1 runn+ = #h miles 9 a ,n4,n4,w4 direction1 & ris+ ?r\gh ,p]mian1 ,bunt] & ,keup] /rata4 ,x is a highly basic oliv9e-basalt1 & is unque/ionably a dyke4 ,mr4 ,j4 ,kirkby1 :o has rec5tly mapp$ & describ$ x 7,trans4 ,nor? ,/af=d%ire ,naturali/s' ,field-,club1 xxviii4 7#ahid71 p4 #abi71 sugge/s t x may be connect$ ) ! igne\s rocks ( ! ,s\? ,/af=d%ire coal-field4 ,b ( ?is idea !re is no evid5ce4 ,! la/ po9t to :i* ! dyke has be5 trac$ is "s five-&-tw5ty miles f ! ne>e/ kn[n portion ( ! dol]ites ( ! coal-field4 ,i h little d\bt t ?is dyke is really an outly+ memb] ( ! great sy/em ( ,t]ti>y dykes describ$ 9 ,book ,,viii4 ( ! pres5t "w4 ,no trace ( v5ts has be5 met ) 9 ! ,coal-measures ( ! ,midl& di/rict or among ! surr\nd+ old] rocks1 nor any pro( t ! abundant sills & ve9s 7 connect$ ) ! eruption ( volcanic mat]ials at ! surface4 ,nev]!less1 f ! analogy ( ! /ructure ( ^! intrusive %eets to t ( ! sills 9 su* volcanic di/ricts z ! s\!rn half ( ,scotl&1 we may well believe t !y 7 connect$ "h & !re ) eruptive v5ts1 & ?us t besides ! nor!rn & s\!rn di/ricts ( ,p]mian volcanoes1 !re rose a c5tral gr\p among ! lagoons ( ! he>t ( ,engl&4 ,?\gh no ve/ige ( any su* gr\p has be5 detect$1 we mu/ rememb] t a l>ge portion ( ! ,midl&s is ov]spread ) ,p]mian & ,triassic deposits1 & t mu* m igne\s rock may be conceal$ ?an appe>s at ! surface4 ,possibly !re may be buri$ "u ^! y\ng] %eets ( r$ s&/one & m>l1 lavas & tuffs ) _! connect$ v5ts1 su* z may be se5 :]e ! ,p]mian volcanic s]ies has be5 laid b>e by d5udation 9 ,ayr%ire & ,devon%ire4 ,9 ?is respect x w\ld be int]e/+ to make a ?or\gh exam9ation ( ! ,p]mian breccias ( ! di/rict1 ) ! view ( discov]+ :e!r1 ?\gh ! volcanic rocks 9 situ may /ill lie cov]$ up1 fragm5ts ( !m may n be f\nd 9 ^! deposits4 ,illu/ration3 ,,to ,,accompany ,,sir ,,ar*ibald ,,geikie',s ,,anci5t ,,volcanoes ,,( ,,brita9 ,map ,v4 ,,map ,,( ,,! ,,p]mian ,,volcanic ,,di/ricts ,,( ,,scotl& ,! ,ed9burgh ,geographical ,in/itute ,copyright ,j4 ,g4 ,b>?olomew4 ,,book ,,viii ,,! ,,volcanoes ,,( ,,t]ti>y ,,"t ,,*apt] ,,xxxiii ,va/ lapse ( "t betwe5 ! close ( ! ,palozoic & beg9n+ ( ! ,t]ti>y ,volcanic ,eruptions--,prolong$ ,volcanic ,quiesc5ce--,progress ( ,inve/igation among ! ,t]ti>y ,volcanic ,s]ies ( ,brita94 ,f ! evid5ce :i* has be5 l$ 9 ! =ego+ *apt]s x is cle> t dur+ ! lat] /ages ( ! ,palozoic p]iod !re 0 a gradual enfeeblem5t ( volcanic vig\r ov] ! area ( ! ,briti% ,isles4 ,:5 ! la/ puys ( ! ,p]mian s]ies became ext9ct a rem>kable volcanic quiesc5ce settl$ d[n on ! region4 ,?is int]val ( re/ la/$ ?r\gh\t ! :ole ( ! long succession ( ! ,mesozoic ages4 ,?\gh ! geological record ( ?is section ( geological "t is s+ul>ly complete 9 ,brita91 n a s+le ve/ige has yet be5 f\nd 9 x ( any contemporane\s eruption4 ,& :at is true ( ?is c\ntry is1 on ! :ole1 true ( ! entire ,european cont95t4 ,) "s trifl+ exceptions !re 7 no volcanoes 9 ,europe1 s f> z we "k1 dur+ ! enorm\s lapse ( "t betwe5 ! la/ ( ! ,palozoic & ! e>lie/ ( ! ,t]ti>y eruptions4 ,:5 ! geologi/ attempts to =m an e/imate ( ! *ronological value ( ?is int]val ( "t he is soon lo/ 9 bewild]m5t ov] its obvi\s va/ness1 & ! impossibility ( discov]+ any /&>ds ( measurem5t by :i* to reckon its duration4 ,on ! "o h&1 he sees t x la/$ long en\gh to admit ( ! gradual elaboration ( _m ?\s&s ( feet ( v>i\s s$im5t>y deposits1 :i*1 f _! rem>kable div]sities ( "*1 7 evid5tly accumulat$1 on ! :ole1 ) extreme sl[ness & amid/ _m geographical vicissitudes4 ,on ! o!r h&1 he p]ceives t ! int]val suffic$ to br+ ab\t an entire *ange 9 ! fauna & flora ( ! globe4 ,inde$1 ! m he inve/igates ! details ( ?is biological trans=mation1 ! m he is impress$ ) ! l5g? ( "t t x mu/ h requir$4 ,= x is n m]ely "o complete *ange1 b a multifold succession ( *anges4 ,! /ratigraphical records ( ! long array ( geological p]iods ov] :i* x 0 spread %[ t ! biological evolution advanc$ ?r\gh a va/ s]ies ( species1 g5]a & ord]s :i* "o by "o appe>$ & disappe>$4 ,! ages t elaps$ betwe5 ! f9al dy+ out ( ! ,palozoic volcanoes & ! outbur/ ( ^? ( ,t]ti>y "t 7 s protract$ t _m revolutions ( ! geography ( ,europe 7 compris$ )9 !m4 ,l& & sea *ang$ places aga9 & aga94 ,fir/ came ! s+ul> topography ( ! ,trias1 :i* prolong$ & acc5tuat$ ! *>act]i/ics ( ! clos+ ,palozoic ages4 ,next arose ! m g5ial climate & m v>i$ geography ( ! ,jurassic p]iod1 :5 comp>atively %all[ seas ov]spread ! site ( mo/ ( ! ,european cont95t1 & tracts ( old l& /ret*$ away to ! we/ & nor?4 ,ano!r cr[d$ succession ( *anges 9 ! disposition ( l& & sea fill$ ! long ,cretace\s p]iod1 at ! close ( :i* a m rapid & complete trans=mation 9 ,european geography took place4 ,yet dur+ all ^! transitions & vicissitudes1 s f> z we "k1 volcanic en]gy rema9$ quiesc5t ?r\gh\t ,we/]n ,europe4 ,x 0 n until "s "t aft] ! great t]re/rial movem5ts t rais$ s mu* ( ! ,cretace\s sea-floor into l&1 & laid ! f\ndations ( ! mod]n cont95t1 t ! subt]ranean fires once m awoke to vigor\s action4 ,! r5ewal ( eruptions 9 ! e>ly ages ( ,t]ti>y "t 0 z widespread z x 0 en]getic4 ,ov] _m regions ( ! ,european cont95t volcanoes broke out ei!r 9 new areas or on old sites4 ,= ! mo/ "p !y appe>$ z scatt]$ puys or z ,vesuvian v5ts1 g5]ally n ( ! fir/ magnitude1 l ^? ( ,c5tral ,france1 ,hung>y1 ,wrtemb]g & ,italy4 ,b 9 ! nor?-we/ !y assum$ m colossal proportions1 & took ! =m ( fissure-eruptions by :i* _m ?\s&s ( squ>e miles ( c\ntry 7 delug$ ) lava4 ,f ! ,s\? ( ,antrim all along ! ,we/ ( ,scotl& to ! nor? ( ! ,inn] ,hebrides rema9s ( ^! basalt-floods =m /rik+ features 9 ! exi/+ sc5]y4 ,! same k9d ( rocks reappe> 9 ! ,f>oe ,isl&s & 9 ,icel&1 s t an enorm\s tract ( ,nor?-we/]n ,europe1 mu* ( x n[ subm]g$ "u ! sea1 0 ! sc5e ( activity ( ! ,t]ti>y volcanoes4 ,9 ent]+1 !re=e1 ^u a consid]ation ( ! ,briti% ,t]ti>y volcanic rocks1 we are br\ght face to face ) ! records ( ! mo/ /up5d\s succession ( volcanic ph5om5a 9 ! :ole geological hi/ory ( ,europe4 ,=tunately ^! records h be5 fully pres]v$ 9 ! ,briti% ,isles1 s t ample mat]ials rema9 !re = ! elucidation ( ?is la/ & mo/ m>vell\s ( all ! volcanic epo*s 9 ! evolution ( ! cont95t4 ,z ! rema9s ( ! ,t]ti>y s]ies ( volcanic eruptions are ! y\nge/ ( all ! volcanic records ( ,brita91 !y are naturally ! fre%e/ & mo/ abundantly pres]v$4 ,!y consequ5tly reveal ) s+ul> cle>ness multitudes ( volcanic ph5om5a t are less di/9ctly recognizable1 or n to be f\nd at all1 among ! ,palozoic sy/ems4 ,h5ce !y w be discuss$ 9 great] detail 9 ! foll[+ *apt]s4 ,z a consequ5ce ( _! great] fre%ness & wid] ext5t1 & l>gely also because ( ! way 9 :i* !y h be5 expos$ along _m leagues ( picturesque sea-cliffs 9 ! ,nor? ( ,irel& & ! ,we/ ( ,scotl&1 !y attract$ att5tion at an e>li] "t ?an ! less obvi\s volcanic memorials ( old] ages4 ,! gradual developm5t ( op9ion reg>d+ ! nature & hi/ory ( volcanic rocks is ?us 9 no small measure b\nd up ) ! progress ( obs]vation & inf]5ce 9 reg>d to ! ,t]ti>y volcanic s]ies4 ,i %all !re=e beg9 ?is n>rative by (f]+ a rapid sket* ( ! hi/ory ( inquiry respect+ ! ,t]ti>y volcanic areas ( ! ,briti% ,isles4 ,! basaltic cliffs ( ,antrim & ! ,inn] ,hebrides _h attract$ ! notice ( pass+ travell]s1 & _! /rik+ sc5]y _h become m or less famili> to ! read+ public1 be=e any att5tion 0 paid to _! rem>kable geological /ructure & hi/ory4 ,9 p>ticul>1 ! wond]s ( ! ,giant's ,causeway & ! ,antrim coa/ _h already begun to draw pilgrims1 ev5 f di/ant c\ntries1 at a "t :5 geology _h n come into exi/5ce4 ,! sci5tific t\ri/ ( ^? days :o might c>e to look at rocks 01 9 mo/ cases1 a m9]alogi/1 = :om _! /ructural relations & orig9 7 subjects t lay outside ( ! range ( 8 k or habits ( ?\ght4 ,9 ! ye> #aggb ,sir ,joseph ,banks1 toge!r ) ,sol&] & a p>ty1 visit$ ,/affa & br\ght back ! e>lie/ acc\nt ( ! m>vels ( t isle z !y appe>$ to ! sob] eyes ( sci5ce4 ,8 n>rative 0 communicat$ to ,p5nant1 toge!r ) a numb] ( draw+s ( ! cliffs & ( ,f+al's ,cave4 ,^! 7 ins]t$ by t geograph] 9 8 ,second ,t\r1 publi%$ 9 #aggd1 & f _! c>eful measurem5ts ( ! basaltic pill>s & _! del9eation ( ! basaltic /ructure1 are ( special int]e/ 9 ! hi/ory ( volcanic geology4 ,an intellig5t appreciation ( "s ( ! geological int]e/ ( ! region is to be f\nd 9 ! writ+s ( ,:itehur/1#abe :o gave a good acc\nt ( ! basalt-cliffs ( ,antrim1 & reg>d$ ! basaltic rocks z ! results ( successive outfl[s ( lava f "s c5tre n[ subm]g$ b5ea? ! ,atlantic4 ,m important are ! obs]vations conta9$ 9 two lett]s ( ,abraham ,mills4#abf ,?is writ] _h be5 /ruck ) ! dykes on ! nor? coa/ ( ,irel&1 & 0 l$ to exam9e also ^? 9 "s ( ! ne>] ,scotti% isl&s4 ,he believ$ !m to be ( truly volcanic orig91 & spoke ( !m z ve9s ( lava4 ,a few ye>s lat]1 ,faujas ,/4 ,fond made 8 well-kn[n pilgrimage to ! ,we/]n ,isles4 ,famili> ) ! volcanic rocks ( ,c5tral ,france1 he at once recogniz$ ! volcanic orig9 ( ! basalts ( ,mull1 ,/affa & ! adjo9+ isl&s4#abg ,8 acc\nt ( ! j\rney1 publi%$ 9 ,p>is 9 #agig1 may be tak5 z ! beg9n+ ( ! volum9\s geological lit]ature :i* has s9ce ga!r$ r\nd ! subject4 ,?ree ye>s aft]w>ds 7#ahjj7 appe>$ ,jameson's ,outl9e ( ! ,m9]alogy ( ! ,scotti% ,isles4 ,fre% f ! tea*+ ( ,w]n] at ,freib]g1 ! future di/+ui%$ ,pr(essor ( ,natural ,hi/ory 9 ! ,ed9burgh ,univ]sity naturally saw ev]y?+ 9 ! peculi> ,w]n]ian light4 ,he gave ! fir/ detail$ enum]ation ( "s ( ! eruptive rocks ( ! ,hebrides1 b ( c\rse ridicul$ ! idea ( _! igne\s orig94 ,hav+ he>d ( a report$ crat] ( a volcano ne> ,portree1 he ironically express$ a hope t !re may be /ill suffici5t heat to revive ! spirits ( "s =lorn fire-philosoph]1 z he w&]s ?r\gh ?is cold1 bleak c\ntry4#abh ,footnote #abe3 ,inquiry into ! ,orig9al ,/ate & ,=mation ( ! ,e>?1 #bnd edit4 #aghf4 ,footnote #abf3 ,philosophical ,transactions = #agij4 ,footnote #abg3 ,voyage en ,anglet]re1 en cosse et aux les ,hbrides4 ,p>is1 #agig4 ,footnote #abh3 ,x w be %[n 9 a lat] *apt] t !re is a rem>kably p]fect volcanic v5t ne> ,portree1 b ! suppos$ crat] ref]r$ to by ,jameson 0 probably "s little corry among ! %eets ( basalt4 ,! adv5t ( ,jameson to ,ed9burgh gave a fre% impetus to ! w>f>e ( ! ,plutoni/s & ,neptuni/s1 = he br\ght to ! ranks ( ! latt] a m9]alogical skill su* z none ( _! ,scotti% oppon5ts c\ld boa/4 ,! igne\s orig9 ( basalt1 :i* ! ,plutoni/s /\tly ma9ta9$1 0 z /rongly d5i$ by ! o!r side4 ,= "s ye>s "o ( ! mo/ tell+ argum5ts aga9/ ! foll[]s ( ,hutton 0 d]iv$ f ! alleg$ occurr5ce ( fossil %ells 9 ! basalt ( ! nor? coa/ ( ,irel&4 ,kirwan#abi quot$ ) evid5t satisfaction ,ri*>dson's obs]vation ( %ells 9 ! basalts ( ,ballyca/le1 & ,ri*>dson#acj himself1 ?\gh ! true explanation1 t ! suppos$ basalt is only ,lias %ale alt]$ by basalt1 _h be5 /at$ 9 #ahjb by ,playfair1#aca cont9u$ = t5 ye>s aft]w>ds to reit]ate 8 belief 9 ! aque\s orig9 ( basalt4 ,?us ! ,t]ti>y volcanic rocks furni%$ effective weapons to ! combatants on bo? sides4 ,! dispute reg>d+ ! black fossilif]\s rocks ( ,portru% _h ! effect ( draw+ special att5tion to ! geology ( ! ,nor? ( ,irel&4 ,among ! m not$ geologi/s :o 7 l$ to exam9e !m1 p>ticul> ref]5ce mu/ be made to ,conybe>e & ,buckl&1 :o1 9 ! ye> #ahac1 /udi$ ! int]e/+ coa/-sections ( ,antrim4 ,! report ( _! obs]vations gives an excell5t summ>y ( ! argum5ts = ! truly igne\s orig9 ( basalt1 & a /atem5t ( op9ion 9 fav\r ( ! view t ! b$d$ basalts are ! products ( subm>9e volcanoes4 ,b]g] also ab\t ! same "t describ$ 9 full] detail ! geology ( ! ,antrim di/rict1 & %[$ ! rocks ( ! basalt-plateau to be y\ng] ?an ! ,*alk4 ,he likewise made a /udy ( ! basalt-dykes ( ! ,nor? ( ,irel&1 & 0 ! fir/ to po9t out _! preval5t nor?-we/]ly direction4 ,! memoirs ( ^! geologi/s#acb may ju/ly be reg>d$1 to quote ! words ( ,portlock1 z ! fir/ effectual /ep made 9 ,iri% geology4 ,portlock's own description is /ill ! mo/ complete summ>y ( ! geology ( t int]e/+ region4#acc ,footnote #abi3 ,geological ,essays1 #agii1 p4 #beb1 footnote4 ,footnote #acj3 ,ri*>dson liv$ on ! ,antrim coa/1 & _h daily opportunities ( exam9+ ! admirable rock-sections !re expos$4 ,x 0 he :o f\nd ! %ells 9 suppos$ basalt1 & l$ ! geologi/s ( 8 day a/ray on ?is subject4 ,he made a clev] b irrelevant reply to ,playfair's pla9 /atem5t ( facts 7,trans4 ,roy4 ,iri% ,acad4 vol4 ix4 #ahjc1 p4 #dha74 ,8 elaborate attack on ! ,volcanic ,!ory w be f\nd 9 ,trans4 ,roy4 ,iri% ,acad4 vol4 x4 7#ahjf71 pp4 #ce-ajg4 ,?\gh lively en\gh z a specim5 ( controv]sial writ+1 x =ms1 :5 s]i\sly consid]$1 r a melan*oly *apt] 9 geological lit]ature4 ,footnote #aca3 ,illu/rations ( ! ,huttonian ,!ory1 #beb4 ,footnote #acb3 ,!y are conta9$ 9 ! ?ird volume ( ! ,transactions ( ! ,geological ,society4 ,footnote #acc3 ,report on ! ,geology ( ! ,c\nty ( ,londond]ry & p>ts ( ,tyrone & ,f]managh1 ,mem4 ,geol4 ,survey1 #ahdc4 ,:ile su* advances 7 be+ made 9 ! k ( ! /ructure ( ! volcanic rocks ( ! ,nor? ( ,irel&1 ! geologi/ _h already appe>$ :o 0 ! fir/ to attempt a sy/ematic exam9ation ( ! ,we/]n ,isl&s1 & ^: publi%$ descriptions are /ill a *ief s\rce ( in=mation reg>d+ ! geology ( ?is ext5sive region4 ,dr4 ,maccullo* seems to h made 8 fir/ explorations among ! ,hebrides "s "t previ\s to ! ye> #ahad1 = 9 t ye> he publi%$ "s rem>ks on specim5s f t di/rict transmitt$ to ! ,geological ,society4#acd ,= sev]al ye>s 9 succession he devot$ himself ) great en]gy & en?usiasm to ! self-impos$ task ( geologically exam9+ & mapp+ 9 a g5]aliz$ way all ! isl&s t lie to ! we/w>d ( ,scotl&1 f ! remote ,/4 ,kilda ev5 z f> z ! ,isle ( ,man4 ,f "t to "t1 notices ( p>ts ( 8 "w 7 giv5 9 ! ,transactions ( ! ,geological ,society4 ,b ev5tually 9 #ahai he embodi$ ! :ole 9 8 ,description ( ! ,we/]n ,isl&s ( ,scotl&1 includ+ ! ,isle ( ,man4 ,footnote #acd3 ,trans4 ,geol4 ,soc4 vol4 ii4 #ahad4 ,?is great classic m>ks a notable epo* 9 ,briti% geology4 ,prop]ly to e/imate its value1 we %\ld try to realize :at 0 ! /ate ( ! sci5ce 9 ?is c\ntry at ! "t ( its appe>ance4 ,s labori\s a collection ( facts1 & s c\rage\s a resolution to avoid !oriz+ ab\t !m1 gave to 8 volumes an altoge!r unique "*4 ,8 descriptions 7 at once adopt$ z "p ( ! famili> lit]ature ( geology4 ,8 sections & sket*es 7 reproduc$ 9 endless treatises & text-books4 ,few s+le works ( descriptive geology h ev] done s mu* to advance ! progress ( ! sci5ce 9 ?is c\ntry4 ,) reg>d to ! special subject ( ! pres5t memoir1 ,maccullo* %[$ t ! basalts & o!r eruptive rocks ( ! ,inn] ,hebrides pi]ce & ov]lie ! ,second>y /rata ( ^! isl&s1 & mu/ !re=e be ( y\ng] date4 ,b ?\gh he di/+ui%$ ! ?ree great s]ies ( trap-rocks1 sy5ites & hyp]/h5e-rocks or augite-rocks1 & indicat$ approximately _! respective areas1 he did n attempt to unravel _! relations to ea* o!r4 ,nor did he v5ture ^u any speculations z to ! probable conditions "u :i* ^! rocks 7 produc$4 ,he claim$ t ^? :o might foll[ him w\ld f9d a great deal :i* he _h n describ$1 b little t he _h n exam9$4 ,subsequ5t obs]v]s h not$ _m important facts1 ( :i*1 _h he obs]v$ !m1 he w\ld at once h se5 ! mean+1 & :i* he c]ta9ly w\ld n h pass$ ov] 9 sil5ce4 ,b z a fir/ broad outl9e ( ! subject1 ,maccullo*'s "w possesses a great value1 :i* is n less5$ by ! subsequ5t discov]y ( details t escap$ 8 notice1 & ( important geological relations :i* he fail$ to detect4 ,x has already be5 po9t$ out t "s ( ! e>lie/ & able/ obs]vations among ! volcanic rocks ( ?is c\ntry1 especially 9 ,scotl&1 7 made by =eign]s4 ,/ud5ts :o _h repair$ f abroad to ,ed9burgh = education sometimes caught ! geological en?usiasm1 !n s m>k$ 9 t city1 & made num]\s j\rneys ?r\gh ! c\ntry 9 se>* ( fur!r k ( ,scotti% rocks & m9]als4 ,9 o!r in/ances1 geologi/s ( e/abli%$ reputation1 attract$ by ! int]e/ :i* ! publi%$ acc\nts ( ! geology ( ,scotl& _h excit$1 7 l$ to visit ! c\ntry & to record _! impressions ( its rock-/ructure4 ,( ! fir/ class ( obs]v]s ! two mo/ not$ 7 ,ami ,b\ & ,l4 ,a4 ,neck]2 ( ! second1 special ackn[l$gm5t is due to ,faujas ,/4 ,fond & to ,von ,oy5haus5 & ,von ,de*54 ,! lab\rs ( ,b\#ace h already be5 ref]r$ to 9 connection ) ! lit]ature ( ! ,scotti% ,old ,r$ ,s&/one 7vol4 i4 p4 #bfi74 ,9 8 treatm5t ( ! ,t]ti>y ,volcanic s]ies ( ,scotl& he appe>s to h reli$ ma9ly on ! !n rec5tly publi%$ volumes ( ,maccullo*4 ,footnote #ace3 ,essai gologique sur l'cosse4 ,p>is1 #ahbj4 ,l4 ,a4 ,neck]1 z ! gr&son ( ! illu/ri\s ,de ,saussure1 _h /rong claims on ! fri5dly assi/ance ( ! ,s*ool ( ,geology at ,ed9burgh :5 he w5t ?i!r 9 #ahjf1 at ! age ( tw5ty1 to prosecute 8 /udies4 ,he 0 equally well receiv$ by ! ,plutoni/s & ,neptuni/s1 & devot$ "s "t to ! exploration ( ! geology n only ( ! ,l[l&s1 b ( ! ,highl&s & ! ,inn] ,hebrides4 ,mo/ ( 8 obs]vations appe> to h be5 made 9 ! ye> #ahjg1 b x 0 n until f\rte5 ye>s aft]w>ds t he publi%$ ! acc\nt ( !m4#acf ,! geological "p ( ?is "w mu/ be admitt$ to be some:at disappo9t+4 ,! au?or's caution n to commit himself to ei!r side ( ! geological controv]sy !n wag+ makes 8 descriptions & explanations r col\rless4 ,he adds little to :at 0 previ\sly kn[n4 ,ev5 z reg>ds ! orig9 ( ! basalts ( ! ,we/]n ,isl&s1 he c\ld n make up 8 m9d :e!r or n to reg>d !m z volcanic1 b cont5t$ himself by ref]r+ !m to ! trappean =mation4 ,yet ^! isl&s _h s fasc9at$ him t ev5tually he return$ to !m z 8 adopt$ home1 pass$ ! la/ tw5ty ye>s ( 8 life among !m1 & di$ & 0 buri$ !re4 ,besides 8 ,voyage1 he publi%$ 9 ,fr5* an acc\nt ( ! dykes ( ! ,isl& ( ,arran4#acg ,footnote #acf3 ,voyage en cosse et aux les ,hbrides4 ,see also biographical notice ( ,l4 ,a4 ,neck]1 by ,pr9cipal ,j4 ,d4 ,=bes1 ,proc4 ,roy4 ,soc4 ,ed94 v4 7#ahfb71 p4 #ec4 ,footnote #acg3 ,trans4 ,roy4 ,soc4 ,ed94 vol4 xiv4 7#ahdj71 p4 #ffg4 ,among ! =eign geologi/s :o h be5 drawn to ! ,scotti% m\nta9s & isl&s by ! int]e/ ( _! ,t]ti>y volcanic rocks1 ,i h already spok5 ( ,faujas ,/4 ,fond4 ,mu* m important1 h[ev]1 7 ! obs]vations made "s ?irty ye>s lat] by two ,g]man m5 ( sci5ce1 ,von ,oy5haus5 & ,von ,de*54 ,_! c>eful descriptions ( ! geology ( ,skye1 ,eigg & ,arran add$ new mat]ials to ! k already acquir$ by native geologi/s4#ach ,to "s ( ! m int]e/+ p>ts ( _! "w ref]5ce w be made 9 lat] pages4 ,footnote #ach3 ,k>/5's ,ar*iv 7#ahbi71 vol4 i4 p4 #ef4 ,! num]\s trap-dykes ( ,nor?umb]l&1 ,durham & ,nor!rn ,york%ire at an e>ly date attract$ ! att5tion ( geologi/s4 ,z f> back z #ahag1 !y _h be5 ! subject ( a memoir by ,n4 ,j4 ,w9*1#aci :o gave an acc\nt ( _! effects on ! adjac5t rocks4 ,m important 7 ! subsequ5t pap]s on ! same subject by ,s$gwick1 :o1 discuss+ ! li?ological *>act]s1 probable orig9 & geological age ( ! dykes1 po9t$ out t :ile ! ,clevel& dyke 0 und\bt$ly y\ng] ?an a l>ge "p ( ! ,jurassic rocks1 !re 0 no direct evid5ce to det]m9e :e!r dykes f>!r nor? 7 e>li] or lat] ?an ! "t ( ! ,magnesian ,lime/one4#adj ,subsequ5t acc\nts ( ! dykes ( ! same region 7 giv5 by ,buddle1#ada ,m4 ,=/]1#adb ,n4 ,wood1#adc ,h4 ,t4 ,m4 ,)am1#add ,tate #ade & o!rs1 :ile 9 m rec5t ye>s important additions to our k ( ^! dykes & ( _! effects h be5 made by ,sir ,j4 ,l[?ian ,bell#adf & ,mr4 ,j4 ,j4 ,h4 ,teall4#adg ,footnote #aci3 ,trans4 ,geol4 ,soc4 vol4 iv4 7#ahag71 p4 #ba4 ,see also ,tillo*'s ,phil4 ,mag4 vols4 xlix4 & l4 ,footnote #adj3 ,cambridge ,phil4 ,trans4 vol4 ii4 7#ahbg71 pp4 #ba1 #aci4 ,footnote #ada3 ,trans4 ,nat4 ,hi/4 ,soc4 ,nor?umb]l&1 i4 7#ahca71 p4 #i4 ,footnote #adb3 ,op4 cit4 i4 p4 #dd4 ,footnote #adc3 ,op4 cit4 i4 pp4 #cje1 #cjf1 #cjh1 #cji4 ,footnote #add3 ,op4 cit4 ii4 7#ahch71 p4 #cdc4 ,footnote #ade3 ,trans4 ,nor?umb]l& & ,durham1 ii4 7#ahfh71 p4 #cj4 ,footnote #adf3 ,proc4 ,roy4 ,soc4 xxiii4 7#ahge71 p4 #edc4 ,footnote #adg3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 7#ahhd71 p4 #bji4 ,! geological age ( ! great s]ies ( ,t]ti>y volcanic rocks has only be5 det]m9$ di/rict by di/rict1 & at wide int]vals4 ,t "s "p ( ! ,antrim basalts is y\ng] ?an ! ,*alk ( t region 0 cle>ly %[n by ,b]g]1 ,conybe>e & ,buckl&4 ,portlock1 h[ev]1 ref]r$ to ! occurr5ce ( deta*$ blocks ( basalt :i* he suppos$ to be imm]s$ 9 ! ,*alk ne> ,portru%1 & :i* incl9$ him to believe t ! basaltic fl[s comm5c$ at a remote p]iod ( ! ,cretace\s sy/em4#adh ,maccullo* %[$ t ! correspond+ basaltic plateaux ( ! ,inn] ,hebrides 7 c]ta9ly y\ng] ?an ! ,oolitic rocks ( t region4 ,b no ne>] approximation to _! date _h yet be5 made :5 9 ! ye> #ahej ! ,duke ( ,argyll ann\nc$ ! discov]y ( /rata conta9+ fossilif]\s *alk-fl9ts & dicotyl$on\s leaves1 ly+ betwe5 ! b$d$ basalts ( ,ardtun ,head1 9 ! ,isle ( ,mull4#adi ,9 ! foll[+ ye> ^! fossil leaves 7 describ$ by ,edw>d ,=bes1 :o reg>d$ !m z decid$ly ,t]ti>y1 & mo/ probably ,mioc5e4 ,?is 0 ! fir/ palontological evid5ce = ! det]m9ation ( ! geological age ( any portion ( ! basalt-plateaux1 & x indicat$ t ! basalts ( ! s\?-we/ ( ,mull 7 ( old] ,t]ti>y date4 ,tak5 also 9 connection ) ! occurr5ce ( lignite-b$s betwe5 ! basalts ( ,antrim1 x sugge/$ t ^! volcanic plateaux 7 n due to subm>9e eruptions1 z ! e>li] geologi/s _h suppos$1 b 7 r ! result ( ! subrial outp\r+ ( lava at successive int]vals1 dur+ :i* t]re/rial vegetation sprang up ^u ! old] outfl[s4 ,footnote #adh3 ,report on ! ,geology ( ,londond]ry1 p4 #ic4 ,!re c be no d\bt t ?is 0 an error ( obs]vation4 ,! ,antrim basalts are all c]ta9ly y\ng] ?an ! ,*alk4 ,! suppos$ lumps ( basalt 7 probably ! ends ( ve9s intrud$ into ! ,*alk1 & p]haps p>tially disconnect$ f ! ma9 p>ts ( ! ve9s4 ,su* app>5tly deta*$ masses ( intrusive rock are n infrequ5t occurr5ce 9 connection ) ! ,t]ti>y intrusive sills4 ,an example w be f\nd repres5t$ 9 ,fig4 #cba4 ,footnote #adi3 ,brit4 ,assoc4 ,report1 #ahej1 ,sections1 p4 #gj2 & ,qu>t4 ,j\r4 ,geol4 ,soc4 vii4 7#ahea71 p4 #hg4 ,:ile ,=bes br\ght =w>d palontological pro(s ( ! ,t]ti>y age ( ! volcanic rocks ( ! s\?-we/ ( ,mull1 he at ! same "t laid be=e ! ,geological ,society a pap] on ! ,e/u>y ,b$s & ! ,ox=d ,clay ( ,lo* ,/aff91 9 ,skye1 :]e91 :ile admitt+ ! exi/5ce ( appe>ances :i* might be reg>d$ z fav\rable to ! view t ! int]calat$ basalts ( t region 7 ( mu* lat] date ?an ! ,oolitic /rata betwe5 :i* !y might h be5 intrusively inject$1 he /at$ 8 own belief t !y 7 really contemporane\s ) ! associat$ /ratifi$ rocks1 & ?us m>k$ an outbreak ( volcanic en]gy at ! close ( ! ,middle ,oolitic p]iod4#aej ,! ,duke ( ,argyll1 9 ! pap] :i* he on ! same occasion communicat$ to ! ,geological ,society1 adopt$ ?is view ( ! probable age ( mo/ ( ! basalts ( ! ,we/]n ,isl&s4 ,he look$ ^u ! ,t]ti>y volcanic rocks ( ,mull z occupy+ a re/rict$ area1 ! great mass ( ! basalt ( t isl&1 l t ( ,skye1 be+ reg>d$ by him z probably n lat] ?an "s "p ( ! ,second>y p]iod4 ,footnote #aej3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 vii4 7#ahea71 p4 #ajd4 ,x mu/ be grant$ t ! appe>ances ( contemporane\s int]calation ( ! basalt among ! ,second>y /rata are s+ul>ly deceptive4 ,:51 sev]al ye>s aft] ! ann\ncem5t ( ! ,t]ti>y age ( ! basalts ( ,ardtun1 ,i began my geological "w 9 ! ,inn] ,hebrides1 ,i 0 l$ to ! same conclusion z ,edw>d ,=bes1 & express$ x 9 an e>ly pap]4#aea ,all ov] ! nor? ( ,skye ,i trac$ :at appe>$ to be evid5ce ( ! contemporane\s int]/ratification ( basalts ) ! ,jurassic rocks & ,i conclud$ 7?\gh ) "s res]vation7 t ! :ole ( ! va/ basaltic plateaux ( t isl& 7 n y\ng] ?an "s late "p ( ! ,jurassic p]iod4 ,9 t same pap] ! att5tion ( geologi/s 0 call$ to ! probable connection ( ! great sy/em ( ea/-&-we/ dykes trav]s+ ,scotl& & ! ,nor? ( ,engl&1 ) ! basalt-plateaux ( ! ,inn] ,hebrides1 & z ,i believ$ ! latt] to be probably ( ! age ( ! ,oolitic rocks1 ,i assign$ ! dykes to ! same p]iod 9 geological hi/ory4 ,b subsequ5t explorations enabl$ me to correct ! mi/ake into :i*1 ) o!r geologi/s1 ,i _h fall5 reg>d+ ! age ( ! volcanic ph5om5a ( ! ,we/]n ,isl&s4 ,9 #ahfg ,i %[$ t in/ead ( be+ conf9$ to a m]e corn] ( ,mull1 ! ,t]ti>y basalts1 ) y\ng] associat$ tra*ytic or granitic rocks1 cov]$ ne>ly ! :ole ( t isl&1 & t 9 all likelihood ! long *a9 ( basaltic masses1 ext5d+ f ! ,nor? ( ,irel& along ! we/ coa/ ( ,scotl& to ! ,f>oe ,isl&s1 & beyond ^! to ,icel&1 0 all erupt$ dur+ ! ,t]ti>y p]iod4 ,at ! same "t ,i drew special att5tion to ! sy/em ( ea/-&-we/ dykes z pro(s ( ! vig\r ( volcanic action at t p]iod1 & ,i furni%$ evid5ce t ?is action 0 prolong$ ?r\gh a va/ int]val ( "t1 dur+ :i* great subrial d5udation ( ! old] lavas took place be=e ! outfl[ ( ! y\ng]4#aeb ,lat] 9 ! same ye>1 9 an address to ! ,geological ,section ( ! ,briti% ,association1 ,i reit]at$ ^! views1 & m p>ticul>ly emphasiz$ ! importance ( ! sy/em ( dykes1 :i* 9 my op9ion 0 possibly ! mo/ /rik+ manife/ation ( ! vig\r ( ,t]ti>y volcanic action4#aec ,9 #ahga1 aft] fur!r explorations 9 ! field1 ,i gave a detail$ acc\nt ( ! /ructure :i* _h l$ to ! mi/ake z to ! age ( ! ,t]ti>y volcanic rocks ( ! ,we/]n ,isl&s2 & 9 a description ( ! isl& ( ,eigg1 ,i br\ght =w>d data to %[ ! enorm\s duration ( ! ,t]ti>y volcanic p]iod 9 ! we/ ( ,brita94#aed ,footnote #aea3 ,on ! ,*ronology ( ! ,trap-rocks ( ,scotl&1 ,trans4 ,roy4 ,soc4 ,ed94 xxii4 7#ahfa71 p4 #fdi4 ,footnote #aeb3 ,proc4 ,roy4 ,soc4 ,ed94 vi4 7#ahfg71 p4 #ga4 ,footnote #aec3 ,brit4 ,assoc4 ,report 7,dundee71 #ahfg1 ,sections1 p4 #di4 ,footnote #aed3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxvii4 7#ahga71 p4 #bgi4 ,?ree ye>s lat] ,mr4 ,j4 ,w4 ,judd read be=e ! ,geological ,society a pap] ,on ! ,anci5t ,volcanoes ( ! ,highl&s4#aee ,! mo/ novel feature ( ?is pap] 0 ! ann\ncem5t t ! au?or _h recogniz$ ! basal wrecks ( five great c5tral volcanoes 9 ! ,we/]n ,isl&s1 among :i* t ( ,mull 0 inf]r$ by him to h be5 at lea/ #ad1ejj feet high4 ,he 0 l$ to ! conclusion t ! volcanic p]iod 9 ^! regions 0 divisible into ?ree sections--! fir/ m>k$ by ! outbur/ ( acid rocks 7felspa?ic lavas & a%es1 connect$ ) deep] & m c5tral granitic masses72 ! second by ! extrusion ( basic lavas & tuffs 7! basaltic plateaux72 ! ?ird by ! appe>ance ( small sporadic volcanic cones 7felspa?ic1 basaltic1 or int]m$iate 9 composition7 aft] ! great c5tral cones _h become ext9ct4 ,x w be se5 9 ! foll[+ pages t ^! conclusions ( ,pr(essor ,judd are n support$ by a m detail$ /udy ( ! region4 ,footnote #aee3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxx4 7#ahgd71 p4 #bbj4 ,9 ! ye> #ahgi1 dur+ a trav]se ( "s portions ( ! volcanic region ( ,wyom+1 ,montana & ,utah1 ,i 0 vividly impress$ by ! id5tity ( /ructure betwe5 ! basaltic plateaux ( ^! t]ritories & ! y\nge/ volcanic areas ( ,brita94 ,x !n appe>$ to me t "s ( ! puzzl+ features 9 ! ,t]ti>y volcanic s]ies ( ! ,inn] ,hebrides might be expla9$ by ! /ructures s admirably display$ 9 ^! lava-fields ( ! ,f> ,we/4#aef ,rid+ ov] ! great basalt-pla9s ( ! ,snake ,riv] & look+ at ! sections cut by ! riv] ?r\gh ! ?ick s]ies ( horizontal basalt-b$s1 ,i appreciat$ = ! fir/ "t ! significance ( ,b>on von ,ri*?(5's views reg>d+ massive or fissure eruptions1 z contradi/+ui%$ f ^? ( great c5tral cones ( ! type ( ,etna or ,vesuvius1 & ,i ga!r$ s _m sugge/ions f my exam9ation ( ^! ,am]ican regions t ,i r5ew$ ) increas$ int]e/ ! inve/igation ( ! ,t]ti>y volcanic tracts ( ,brita94 ,at la/1 aft] ano!r int]val ( n9e ye>s1 dur+ :i* my weeks ( leisure 7 giv5 to ! task1 ,i 0 able to complete a discussion ( ! :ole hi/ory ( ,t]ti>y volcanic action 9 ?is c\ntry1 :i* 0 communicat$ to ! ,royal ,society ( ,ed9burgh 9 ! e>ly summ] ( #ahhh4aeg ,s9ce t "t ,i h cont9u$ ! rese>*1 & h f "t to "t communicat$ my results to ! ,geological ,society4 ,^! v>i\s memoirs are comb9$ ) hi!rto unpubli%$ details 9 ! foll[+ acc\nt ( ! ,briti% ,t]ti>y ,volcanic ,rocks4 ,footnote #aef3 ,geological ,essays at ,home & ,abroad 7#ahhb71 pp4 #bga1 #bgd2 ,nature1 ,novemb] #ahhj4 ,footnote #aeg3 ,trans4 ,roy4 ,soc4 ,ed94 vol4 xxxv4 "p ii4 7#ahhh71 pp4 #bc-ahd4 ,pr(essor ,judd has also prosecut$ ! inve/igation ( ! petrography ( ! rocks1 & has publi%$ 8 obs]vations 9 ! ,qu>t]ly ,j\rnal ( ! ,geological ,society4#aeh ,to ^! pap]s by him m detail$ ref]5ce w be made 9 lat] ,*apt]s4 ,footnote #aeh3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vols4 xlv4 7#ahhi71 xlvi4 7#ahij71 xlix4 7#ahic74 ,9 ! fir/ ( ^! volumes ,pr(essor ,judd (f]$ a detail$ criticism ( my views z to ! ord] ( succession & hi/ory ( ! volcanic rocks ( ! ,inn] ,hebrides4 ,subsequ5t inve/igation hav+ entirely confirm$ my ma9 conclusions1 x is n necess>y to ent] "h ^u matt]s ( controv]sy4 ,ref]5ce1 h[ev]1 w be made 9 subsequ5t ,*apt]s to "s ( ! po9ts 9 dispute4 ,9 describ+ ! geological hi/ory ( a great s]ies ( rocks1 *ronological ord] is usually ! mo/ conv5i5t me?od ( treatm5t4 ,:]e1 h[ev]1 ! rocks are ( volcanic orig91 & d n always precisely indicate _! relative age1 & :]e moreov] ! same k9ds ( rock may appe> on widely-sep>at$ geological horizons1 x is n always possible or desirable to adh]e to ! /rict ord] ( sequ5ce4 ,) ?is necess>y latitude1 ,i propose to foll[ ! *ronological succession f ! old] to ! new] portions ( ! s]ies4 ,i %all treat fir/ ( ! sy/em ( dykes1 by :i* s l>ge a "p ( ,scotl& & ( ! nor? ( ,engl& & ,irel& is trav]s$4 ,_m ( ! dykes are und\bt$ly among ! y\nge/ memb]s ( ! volcanic s]ies1 & 9 no case has _! age be5 z yet det]m9$ except relatively to ! antiquity ( ! rocks :i* !y trav]se4 ,!y mu/1 ( c\rse1 be po/]ior to ^! rocks1 & h5ce x w\ld be q logical to res]ve !m = discussion at ! v end ( ! :ole volcanic ph5om5a4 ,my reason = tak+ !m at ! beg9n+ w be app>5t 9 ! sequel4 ,aft] ! dykes1 ,i %all describe ! great volcanic plateaux :i*1 9 spite ( va/ d5udation1 /ill survive 9 ext5sive fragm5ts 9 ,antrim1 ! ,inn] ,hebrides & ! ,f>oe ,isl&s4 ,! eruptive bosses ( basic rocks t h brok5 ?r\gh ! plateaux w next be discuss$4 ,an acc\nt w !n be giv5 ( ! protrusions ( acid rocks :i* h disrupt$ ^! basic bosses4 ,! la/ *apt]s w conta9 a sket* ( ! subsid5ces & dislocations :i* ! basalt-plateaux h suff]$1 & ( ! d5udation to :i* !y h be5 subject$4 ,z has be5 expla9$ 9 ,*apt] iii41 ! volcanic cycle ( any di/rict1 dur+ a giv5 geological p]iod1 embraces ! :ole range ( erupt$ products f ! beg9n+ to ! end ( a complete s]ies ( eruptions4 ,ref]5ce 0 made 9 ,book ,i4 to ! rem>kable v>iation 9 ! "* ( ! lavas successively p\r$ out f ! same volcanic res]voir dur+ ! cont9uance ( a s+le cycle1 & x 0 po9t$ out t ,ri*?(5's law g5]ally holds good t :ile ! fir/ eruptions may be ( a basic or av]age & int]m$iate nature1 ^? ( succe$+ int]vals become progressively m acid1 b are (t5 f\nd to return aga9 at ! close to ?or\ghly basic comp\nds4 ,?is law is well illu/rat$ by ! volcanic hi/ory ( ,t]ti>y "t 9 ,brita94 ,we %all f9d t ! e>lie/ eruptions ( :i* ! relative date is kn[n consi/$ g5]ally ( basic lavas 7dol]ites & basalts71 b includ+ also m sp>+ly &esites1 tra*ytes & rhyolites2 t ! olde/ intrusive masses consi/$ ( bosses1 sills & dykes ( dol]ite & gabbro2 t ^! intrusions 7 foll[$ by o!rs ( a mu* m acid "*--felsites1 pit*/ones1 qu>tz-porphyries or rhyolites1 granophyres & granites2 t ! late/ lava is a some:at acid rock1 be+ a vitre\s =m ( dacite2 & t ! mo/ rec5t volcanic products ( all are dykes ( a ?or\ghly basic nature1 l "s ( ! e>li] intrud$ masses4 ,,*apt] ,,xxxiv ,,! ,,sy/em ,,( ,,dykes ,,9 ,,! ,,t]ti>y ,,volcanic ,,s]ies ,geographical ,di/ribution--,two ,types ( ,protrusion--,nature ( ,compon5t ,rocks--,hade--,bread?--,int]ruptions ( ,lat]al ,cont9uity--,l5g?--,p]si/5ce ( ,m9]al ,*>act]s4 ,if a geologi/ 7 ask$ to select t feature 9 ! volcanic geology ( ! ,briti% ,isles :i*1 m ?an any o!r1 m>ks ?is region (f f ! re/ ( ! ,european area1 he w\ld probably *oose ! rem>kable sy/em ( wall-l masses ( erupt$ igne\s rock1 to :i* ! old ,saxon ^w dykes has be5 affix$4 ,f ! moors ( ea/]n ,york%ire to ! ,p]?%ire ,highl&s1 & f ! bas9s ( ! ,=? & ,tay to ! we/ ( ,donegal & ! f> headl&s ( ! ,hebrides1 ! c\ntry is ribb$ across ) ^! s+ul> protrusions to su* an ext5t t x may be reg>d$ z a typical region = ! /udy ( ! ph5om5a ( dykes4 ,t all ! dykes 9 ?is wide tract ( c\ntry are ( ,t]ti>y age _c be ma9ta9$4 ,x has be5 %[n 9 previ\s ,*apt]s t ea* ( ! great volcanic p]iods has _h its sy/em ( dykes1 ev5 z f> back z ! "t ( ! ,lewisian ,gneiss4 ,b :5 all ! dykes :i* c reasonably be ref]r$ to old] geological p]iods are exclud$1 !re rema9s a l>ge s]ies :i* _c be s ref]r$1 b :i* are connect$ toge!r by v>i\s k9ds ( evid5ce into "o great sy/em t mu/ be ( late geological date1 & c be assign$ to no o!r ?an ! ,t]ti>y p]iod 9 ! volcanic hi/ory ( ,brita94 ,z f> back z ! ye> #ahfa1 :5 ,i fir/ drew att5tion to ?is great sy/em ( dykes 9 connection ) ! progress ( volcanic action 9 ! c\ntry1 ,i po9t$ out ! gr\nds on :i* x seem$ to me t ^! rocks belong to a comp>atively rec5t geological p]iod4#aei ,my own subsequ5t exp]i5ce & ! full details ( /ructure collect$ by my colleagues ( ! ,geological ,survey 9 all p>ts ( ! c\ntry1 h amply confirm$ ?is view4 ,! *>act]s :i* l9k ?is great s]ies ( dykes toge!r z "o connect$ sy/em ( late geological date are briefly enum]at$ 9 ! foll[+ li/1 & w be m fully discuss$ 9 lat] pages4 ,footnote #aei3 ,trans4 ,roy4 ,soc4 ,ed94 vol4 xxii4 7#ahfa71 p4 #fej4 #a4 ,! preval5t t5d5cy ( ! dykes to take a nor?-we/]ly c\rse4 ,!re are exceptions to ?is normal tr5d1 especially :]e ! dykes are small & locally num]\s2 b x rema9s s+ul>ly *>act]i/ic ov] ! :ole region4 #b4 ,! increas+ abundance ( ! dykes z !y are trac$ to ! we/ coa/ & ! l9e ( ! great ,t]ti>y volcanic plateaux ( ,antrim & ! ,inn] ,hebrides4 #c4 ,! rectil9e> direction s *>act]i/ic ( !m & s diff]5t f ! tortu\s c\rse ( local gr\ps ( dykes4 ,! exceptions to ?is normal feature are z a rule conf9$ to ! same localities :]e dep>tures f ! preval5t we/]ly tr5d occur4 ,illu/ration3 ,fig4 #bcc4--;,dyke on ! s\?-ea/ coa/ ( ! ,isl& ( ,mull4 #d4 ,! great bread? ( ! l>g] dykes ( ! sy/em & _! p]si/5ce = long di/ances4 ,?is is "o ( _! mo/ rem>kable & di/9ctive *>act]s4 #e4 ,! po/]iority ( ! dykes to ! re/ ( ! geological /ructure ( ! regions :i* !y trav]se4 ,!y are n only y\ng] ?an ! o!r rocks1 b y\ng] ?an ne>ly all ! folds & faults by :i* ! rocks are affect$4 #f4 ,! mann] 9 :i* !y cut ! ,jurassic1 ,cretace\s & old] ,t]ti>y rocks 9 ! di/ricts ?r\gh :i* !y run4 ,at ! s\?-ea/]n end ( ! region !y rise ?r\gh ! ,lias & ,oolite =mations1 9 ! we/ !y int]sect ! ,*alk & also ! ,t]ti>y volcanic plateaux toge!r ) _! lat] eruptive bosses4 #g4 ,_! petrographical *>act]s1 among :i* p]haps ! mo/ di/9ctive is ! frequ5t appe>ance ( ! orig9al glass ( ! plagioclase-pyrox5e-magnetite 7oliv9e7 rock1 ( :i* !y mo/ly consi/4 ,?is glass1 or its m or less completely devitrifi$ repres5tative1 (t5 /ill recognizable ) ! microscope among ! individualiz$ microlites & cry/als ?r\gh\t ! body ( a dyke1 is also n infrequ5t z a black vitre\s v>ni%-l coat+ on ! out] walls1 & occasionally appe>s 9 /r+s & ve9s ev5 9 ! c5tre4 ,x is ! assemblage ( dykes pres5t+ ^! features :i* ,i propose to describe4 ,obvi\sly1 ! age ( ea* p>ticul> dyke c only be fix$ relatively = itself4 ,b :5 ?is rem>kable community ( *>act]s is consid]$1 & :5 ! po/-,mesozoic age ( at lea/ a v l>ge numb] ( ! dykes c be demon/rat$1 ! inf]5ce is reasonable t "o great sy/em ( dykes 0 extravasat$ dur+ a "t ( m>k$ volcanic di/urbance1 :i* c\ld n h be5 e>li] ?an ! beg9n+ ( ! ,t]ti>y p]iod4 ,& ?is inf]5ce may be ma9ta9$ ev5 :5 we frankly admit t e dyke )9 ! region is by no means claim$ z belong+ to ! ,t]ti>y s]ies4 ,illu/ration3 ,fig4 #bcd4--;,fissure left by ! wea!r+ out ( a dyke4 ,9 spite ( _! numb] & ! extraord9>y volcanic activity to :i* !y be> witness1 ! dykes =m a mu* less prom95t feature 9 ! l&scape ?an might h be5 anticipat$4 ,9 ! l[l&s ( ! int]ior1 !y h = ! mo/ "p be5 conceal$ "u a cov] ( sup]ficial accumulations1 ?\gh 9 ! wat]-c\rses !y n infrequ5tly project z h>d rocky b>ri]s across ! *annels1 & occasionally =m picturesque wat]falls4 ,on ! b>] upl&s1 !y protrude 9 l9es ( brok5 crag & scatt]$ b\ld]s1 :i* by _! decay give rise to a bett] soil cov]$ by a gre5] vegetation ?an t ( ! surr\nd+ br[n moorl&4 ,among ! ,highl& hills1 !y are (t5 traceable f a di/ance z long black ribs t project f ! nak$ faces ( crag & corry4 ,along ! sea-coa/1 _! peculi>ities ( sc5]y are effectively display$4 ,:]e !y consi/ ( a close-gra9$ rock1 !y (t5 rise f ! bea* z /raight walls :i*1 ) a /rangely artificial look1 m\nt into ! face ( ! cliffs on ! "o side1 & project 9 long black reefs into ! sea on ! o!r 7,fig4 #bcc74 ,e visitor to ! isl&s ( ! ,clyde w rememb] h[ conspicu\s su* features are !re4 ,b x is among ! ,inn] ,hebrides t ?is k9d ( sc5]y is to be f\nd 9 greate/ p]fection4 ,! s(t d>k ,lias %ales ( ! isl& ( ,pabba1 = example1 are ribb$ across ) scores ( dykes :i* /rike boldly out to sea4 ,:]e1 on ! o!r h&1 ! mat]ial ( ! dykes is co>se 9 gra91 or is o!rwise m susceptible to ! dis9tegrat+ influ5ces ( ! wea!r1 x has (t5 rott$ away & left yawn+ clefts beh9d1 ! v]tical walls ( :i* are ^? ( ! fissures up :i* ! molt5 rock asc5d$ 7,fig4 #bcd74 ,"s good in/ances ( ?is k9d are well kn[n to summ] visitors on ! ea/]n %ores ( ,arran4 ,o!rs1 on a l>ge scale1 may be se5 9 ! int]ior ( ! same isl& along ! cre/s ( ! granite ridges1 & /ill m conspicu\sly on ! jagg$ summits ( ,bla? ,be9n & ! ,cuill9 ,hills 7,fig4 #ccc71 & int]sect+ ! ,jurassic /rata along ! cliffs ( ,/ra?aird 9 ,skye4 #a4 ,,geographical ,,di/ribution ,! limits ( ! region )9 :i* ! dykes occur _c be v precisely fix$4 ,!re c be no d\bt1 h[ev]1 t on _! s\!rn side !y rea* to ! ,clevel& ,hills ( ,york%ire & ! s\!rn bord]s ( ,lanca%ire1 p]haps ev5 z f> z ,nor? ,/af=d%ire 7p4 #ajf71 & on ! nor!rn side to ! f>!r %ores ( ! isl& ( ,lewis--a direct di/ance ( #cfj miles4 ,!y /ret* across ! bas9 ( ! ,iri% ,sea1 includ+ ! ,isle ( ,man1 & appe> 9 ,irel& nor? ( a l9e drawn f ,dundalk ,bay to ! ,bays ( ,sligo & ,donegal4 ,dykes are ( frequ5t occurr5ce ov] ! nor? ( ,engl& & s\? ( ,scotl&1 at lea/ z f> nor? z a l9e drawn f ! coa/ ( ,k9c>d9e%ire along ! s\!rn flank ( ! ,grampian ,hills1 by ! head ( ,gl5 ,%ee & ,lo* ,tay1 to ! nor?-we/]n coa/ ( ,argyle%ire4 ,!y ab\nd all along ! l9e ( ! ,inn] ,hebrides & on p>ts ( ! adjac5t coa/s ( ! ma9l&1 f ! remot] headl&s ( ,skye to ! %ores ( ,c\nty ,l\?4 ,!y trav]se also ! *a9 ( ! ,long ,isl& 9 ! ,out] ,hebrides4 ,s f> z ,i am aw>e1 !y are ei!r abs5t or extremely r>e 9 ! ,highl&s nor? ( ! l9e ,i h indicat$4 ,b a good _m h be5 f\nd by my colleagues 9 ! c\rse ( ! ,geological ,survey ( ! nor!rn l[l&s ( ,ab]de5%ire & ,banff%ire4 ,! longe/ ( ^! has be5 trac$ by ,mr4 ,l4 ,h9xman = r m ?an two miles runn+ 9 a ne>ly ea/ & we/ direction ?r\gh ! ,old ,r$ ,s&/one ( ,/ra?bogie1 ) an av]age wid? ( ab\t #ce feet4 ,ano!r 9 ! same di/rict has a wid? ( f #de to #ij feet1 & has be5 foll[$ = a ?ird ( a mile4 ,b f> beyond ^! nor!rn examples1 ,i h f\nd a numb] ( n>r[ basalt-ve9s trav]s+ ! ,old ,r$ flag/ones ( ! ,ma9l& ( ,orkney1 :i* ,i h little d\bt are also a prolongation ( ! same late s]ies4 ,tak+1 h[ev]1 only ^? we/]n & s\!rn di/ricts 9 :i* ! y\ng] dykes =m a notable feature 9 ! geology1 we f9d t ! dyke-region embraces an area ( upw>ds ( #dj1jjj squ>e miles--t is1 a t]ritory great] ?an ei!r ,scotl& or ,irel&1 & equal to m ?an a ?ird ( ! total l&-surface ( ! ,briti% ,isles 7,map ,i474 ,( ?is ext5sive region ! great] portion has n[ be5 mapp$ 9 detail by ! ,geological ,survey4 ,e kn[n dyke has be5 trac$1 & ! appe>ances x pres5ts at ! surface h be5 record$4 ,we are accord+ly n[ 9 possession ( a l>g] body ( evid5ce ?an has ev] be=e be5 available = ! discussion ( ?is rem>kable feature 9 ! geology ( ! ,briti% ,isles4 ,i h made use ( ?is detail$ in=mation1 & besides ! data accumulat$ 9 my own note-books1 ,i h avail$ myself ( ^? ( my colleagues 9 ! ,survey1 = :i* due ackn[l$gm5t is made :]e !y are cit$4 ,! ,t]ti>y basalt-plateaux ( ,brita9 h _! c\nt]p>t 9 ! ,f>oe ,isl&s & 9 ,icel&1 & :e!r or n ! lava-fields /ret*$ ?r\gh\t ,nor?-we/]n ,europe f ,antrim to ! f>!/ headl&s ( ,ultima ,?ule1 !re c h>dly be any d\bt t1 if n cont9u\s1 ^! volcanic areas 7 at lea/ geologically contemporane\s 9 _! activity4 ,_! *>act]i/ic sc5]y & /ructure are prolong$ ?r\gh\t ! :ole region1 reappe>+ ) all _! famili> aspects alike 9 ,f>oe & 9 ,icel&4 ,i h n se5 ! latt] isl&1 b 9 ! ,f>oe ar*ipelago ,i h f\nd ! dykes to be suffici5tly common1 & to cut ! basalt-plateaux !re 9 ! same way z !y d ^? ( ! ,inn] ,hebrides4 ,on ! :ole1 h[ev]1 dykes d n play1 9 ^! nor!rn isles1 ! important "p :i* !y take 9 ! geology & sc5]y ( ! ,we/ ( ,scotl&4 ,i h n _h suffici5t opportunity to asc]ta9 :e!r !re is a g5]al direction or sy/em among ! ,f>oe dykes4 ,9 ! fjords nor? ( ,?or%av51 & aga9 along ! we/ side ( ,/rom1 _m ( !m %[ an ,e4 & ,w4 /rike or "o f ,e4,n4,e4 to ,w4,s4,w4 #b4 ,,two ,,types ,,( ,,protrusion ,! dykes are f> f be+ equally di/ribut$ ov] ! wide region )9 :i* !y occur4 ,9 c]ta9 limit$ areas !y are cr[d$ toge!r1 sometimes t\*+ ea* o!r to ! almo/ entire exclusion ( ! rocks ?r\gh :i* !y asc5d1 :ile else:]e !y appe> only at int]vals ( sev]al miles4 ,view$ 9 a broad way1 !y may be conv5i5tly gr\p$ 9 two types1 :i*1 ?\gh no h>d l9e c be drawn betwe5 !m1 nev]!less probably po9t to two m or less di/9ct phases ( volcanic action & to m ?an "o p]iod ( intrusion4 ,9 ! fir/1 :i* = ! sake ( di/9ction we may t]m ! ,solit>y type1 !re is ei!r a s+le dyke sep>at$ f its ne>e/ neighb\rs by miles ( int]v5+ & entirely dykeless gr\nd1 or a gr\p ( two or m runn+ p>allel to ea* o!r1 b sometimes a mile or m ap>t4 ,! rock ( :i* !y consi/ is1 on ! :ole1 less basic ?an 9 ! second type2 x includes ! &esitic v>ieties4 ,x is to ?is type t ! great dykes ( ! nor? ( ,engl& & ! s\? & c5tre ( ,scotl& belong4 ,! ,clevel& dyke1 = example1 at its ea/]n end has no kn[n dyke ne> x = _m miles4 ,! coal-field ( ,scotl& is trav]s$ by five ma9 dykes1 :i* run 9 a g5]al s5se p>allel to ea* o!r1 ) int]vals ( f half a mile to ne>ly five miles betwe5 !m4 ,dykes ( ?is type display mo/ conspicu\sly ! ess5tial *>act]s ( ! dyke-/ructure1 9 p>ticul> ! v]tical m>g9al walls1 ! p>allelism ( _! sides1 _! great l5g?1 & _! p]si/5ce 9 ! same l9e4 ,9 ! second1 or :at = brevity may be call$ ! ,greg>i\s type1 ! dykes occur 9 great abundance )9 a p>ticul> di/rict4 ,!y are on ! :ole n>r[]1 %ort]1 less /rik+ly rectil9e>1 m frequ5tly tortu\s & ve9-l1 & g5]ally m basic 9 composition ?an ^? ( ! fir/ type4 ,!y include ! true basalts & dol]ites4 ,illu/rative di/ricts = dykes ( ?is class are ! isl&s ( ,arran1 ,mull1 ,eigg & ,skye4 ,! great s+le or solit>y dykes may be obs]v$ to increase 9 numb]1 ?\gh v irregul>ly1 f s\? to nor?1 & also 9 ,c5tral ,scotl& f ea/ to we/4 ,!y are specially abundant 9 ! tract /ret*+ f ! ,fir? ( ,clyde along a belt ( c\ntry "s ?irty miles broad on ei!r side ( ! ,highl& l9e1 z f> at lea/ z ! valley ( ! ,tay4 ,!y =m also a prom95t feature 9 ! isl&s ( ,jura & ,islay4 ,dykes ( ! greg>i\s type are abundantly & *>act]i/ically display$ 9 ! bas9 ( ! ,fir? ( ,clyde4 ,_! developm5t 9 ,arran =m$ ! subject ( ! int]e/+ pap] by ,neck]1 already m5tion$1 :o catalogu$ & describ$ #adi ( !m1 & e/imat$ _! total numb] 9 ! :ole isl& to be ab\t #aejj4afj ,z ! area ( ,arran is #afe squ>e miles1 !re w\ld be1 accord+ to ?is computation1 ab\t n9e dykes to e squ>e mile4 ,b !y are f> f be+ uni=mly di/ribut$4 ,:ile appe>+ only r>ely 9 _m inl& tracts1 !y are cr[d$ toge!r along ! %ore1 p>ticul>ly at ! s\? end ( ! isl&1 :]e ! numb] 9 ea* squ>e mile mu/ f> exce$ ! av]age j giv54 ,! portion ( ,argyle%ire1 betwe5 ! holl[ ( ,lo* ,long & ! ,fir? ( ,clyde on ! ea/ & ,lo* ,fyne on ! we/1 has be5 f\nd by my colleague1 ,mr4 ,c4 ,t4 ,cl\gh1 to conta9 an extraord9>y numb] ( dykes 7see ,fig4 #beg74 ,! coa/ l9e ( ,r5frew%ire & ,ayr%ire %[s t ! same feature is prolong$ into ! ea/]n side ( ! bas9 ( ! ,clyde e/u>y4 ,b imm$iately to ! we/w>d ( ?is area ! cr[d$ dykes disappe> f ! bas9 ( ,lo* ,fyne4 ,9 ,cantire _! sc>city is z rem>kable z _! abundance 9 ,c[al4 ,footnote #afj3 ,trans4 ,roy4 ,soc4 ,ed94 xiv4 7#ahdj71 p4 #fgg4 ,bo? 9 ! ,nor? ( ,irel& & ?r\gh ! ,inn] ,hebrides1 dykes are s+ul>ly abundant 9 & ar\nd1 b p>ticul>ly b5ea?1 ! great plateaux ( basalt4 ,_! pr(usion 9 ,skye 0 describ$ e>ly 9 ?is c5tury by ,maccullo*1 :o call$ att5tion m especially to _! extraord9>y developm5t 9 ! di/rict ( ,/ra?aird4 ,!y ne>ly equal 9 "s places1 he says1 :5 collectively measur$1 ! /ratifi$ rock ?r\gh :i* !y pass4 ,i h c\nt$ six or eight 9 ! space ( fifty y>ds1 ( :i* ! collective dim5sions c\ld n be less ?an sixty or sev5ty feet4 ,he suppos$ t x w\ld n be an excessive e/imate to reg>d ! igne\s rock z am\nt+ to "o-t5? ( ! bread? ( ! /rata :i* x cuts4#afa ,?is e/imate1 h[ev]1 falls mu* %ort ( ! tru? 9 "s p>ts ( ,/ra?aird1 :]e ! dykes are almo/ or q contigu\s1 & ! ,jurassic /rata1 ?r\gh :i* !y rise1 are h>dly to be se5 at all4 ,footnote #afa3 ,trans4 ,geol4 ,soc4 iii4 7#ahae71 p4 #gi4 ,?is locality is fur!r notic$ on p4 #afd4 ,among ! di/ricts :]e dykes ( ! greg>i\s type ab\nd at a di/ance f any ( ! basalt-plateaux1 ref]5ce %\ld be made to ! curi\s isolat$ tract ( ! c5tral granite core ( ,we/]n ,donegal4 ,9 t area a consid]able numb] ( dykes rises ?r\gh ! granite1 to :i* !y are almo/ :olly conf9$4 ,aga91 f> to ! ea/ ano!r limit$ di/rict1 :]e dykes are cr[d$ toge!r1 lies among ! ,m\rne ,m\nta9s4 ,^! granite hills are probably to be class$ ) ^? ( ,arran1 z portions ( a s]ies ( granite protrusions belong+ to a late "p ( ! ,t]ti>y volcanic p]iod :i* w be treat$ ( 9 ,*apt] xlvii4 ,?\gh ! dykes may be conv5i5tly gr\p$ 9 two s]ies or types1 :i* on ! :ole are tol]ably well m>k$1 x is n always practicable to draw any l9e betwe5 !m1 or to say to :i* gr\p a p>ticul> dyke %\ld be assign$4 ,9 "s di/ricts1 h[ev]1 9 :i* !y are bo? develop$1 we c sep>ate !m )\t difficulty4 ,9 ! ,argyle%ire region above ref]r$ to1 = example1 :i* ,mr4 ,cl\gh has mapp$1 he f9ds t ! abundant dykes belong+ to ! greg>i\s type run 9 a g5]al ,n4,w4 or ,n4,n4,w4 direction1 & di/9ctly int]sect ! mu* sc>c] & less basic dykes ( ! solit>y type1 :i* "h run ne>ly ,e4 & ,w4 7,fig4 #beg74 ,h5ce1 besides _! composition1 di/9ction 9 numb]1 bread?1 rectil9e>ity & p]si/5ce1 ! two s]ies 9 t region demon/rably belong to di/9ct p]iods ( eruption4#afb ,footnote #afb3 ,mr4 ,cl\gh is incl9$ to suspect t ! ,e4 & ,w4 dykes are old] ?an ! ,t]ti>y s]ies & may be lat] ,palozoic4 ,! *>act]i/ic habit 9 greg>i\s dykes ( occurr+ 9 cr[d$ gr\ps :i* are sep>at$ f ea* o!r by int]vals ( v>iable dim5sions1 m>k$ by ! pres5ce ( comp>atively few dykes1 is well illu/rat$ 9 ! di/rict ( ,/ra? 9 ,skye1 :i* inde$ may be tak5 z a typical area = ?is peculi>ity ( di/ribution4 ,:ile ! dykes are !re s+ul>ly abundant 9 ! ,cambrian ,lime/one & ! ,liassic /rata1 !y h be5 f\nd by ,mr4 ,cl\gh & ,mr4 ,h>k] to be comp>atively infrequ5t 9 ! tracts ( ,torridon ,s&/one4 ,x is n easy to und]/& ?is peculi> arrangem5t4 ,z ! ,torridon ,s&/one is ! mo/ anci5t rock ( ! di/rict1 x probably und]lies all ! ,cambrian & ,jurassic =mations1 s t ! dykes :i* p5etrate ^! y\ng] /rata mu/ also rise ?r\gh ! ,torridonian rocks4 ,"s =mations appe> to h be5 fissur$ m readily ?an o!rs1 & ?us to h provid$ m abundant op5+s = ! uprise ( ! basaltic magma f bel[4 ,to ! effect ( su* local diff]5ces 9 ! /ructure ( ! t]re/rial cru/ we h to add ! conc5tration ( ! volcanic foci 9 c]ta9 areas1 ?\gh !re seems no means ( asc]ta9+ :at "p ea* ( ^! causes has play$ 9 ! di/ribution ( ! dykes ( any p>ticul> di/rict4 #c4 ,,nature ,,( ,,compon5t ,,rocks ,! ,t]ti>y dykes ( ,brita9 include repres5tatives ( f\r di/9ct gr\ps ( igne\s rocks4 #a/1 ,! va/ majority ( !m consi/ ( plagioclase-pyrox5e-magnetite rocks ) or )\t oliv9e4 ,^! are ! normal basalts & dol]ites4 #bnd1 ,a numb] ( l>ge dykes h a r m acid composition & are class$ z &esites4 #crd1 ,a few dykes ( tra*yte h be5 obs]v$ 9 ,c[al & 9 ,skye cutt+ ! dykes ( basalt 7p4 #ach74 #d?1 ,9 "s di/ricts l>ge numb]s ( /ill m acid dykes occur4 ,^! are sometimes cry/all9e 9 /ructure 7granophyre71 m frequ5tly felsitic 7felsite1 sph]ulitic qu>tz-porphyry71 & (t5 glassy 7pit*/one74 ,9 "s exceptional cases ! basic & acid mat]ials are conjo9$ 9 ! same dyke4 ,su* comp\nd v>ieties are describ$ at p4 #afa4 ,! acid dykes1 connect$ z !y s g5]ally are ) ! l>ge bodies ( granophyre or granite1 are d\btless y\ng] ?an ! great majority ( ! basic dykes4 ,!y w be treat$ 9 connection ) ! acid intrusions 9 ,*apt] xlviii4 ,by f> ! great] numb] ( ! dykes ( ! ,t]ti>y volcanic s]ies belong to ! fir/ gr\p1 & x is ^! m especially :i* w be discuss$ 9 ! pres5t & ! foll[+ ,*apt]4 ,z1 h[ev]1 ! &esitic gr\p is intimately l9k$ ) ! basaltic x w be "h includ$ ) !m4 #a4 ,basalt1 ,dol]ite & ,&esite ,dykes4--,to ! field-geologi/1 :o reg>ds m]ely _! ext]nal features1 ! ,t]ti>y dykes pres5t a /rik+ uni=mity 9 g5]al petrographical "*4 ,!y v>y inde$ 9 f95ess or co>s5ess ( texture1 9 ! pres5ce or abs5ce ( porphyritic cry/als1 amygdales1 glassy portions & o!r po9ts ( /ructure4 ,b !re is seldom any difficulty 9 p]ceiv+ t !y g5]ally belong to "o or o!r ( ! types ( ! basalts1 dol]ites1 diabases or &esites4 ,?is sam5ess ( composition1 traceable f ,york%ire to ,skye & f ,donegal to ,p]?%ire1 is "o ( ! /ronge/ argum5ts = ref]r+ ?is sy/em ( dykes to "o geological p]iod4 ,at ! same "t1 !re are en\gh ( m9or v>iations & local peculi>ities to af=d abundant ex]cise = ! obs]v+ faculties alike 9 ! field & 9 ! /udy1 & to (f] mat]ials = arriv+ at "s positive conclusions reg>d+ ! geological processes involv$ 9 ! uprise ( ! dykes4 ,!re appe>s to be reason to believe t1 :5 ! petrography ( ! dykes is m m9utely /udi$1 m>k$ diff]5ces ( mat]ial w be f\nd to d5ote di/9ct p]iods ( eruption4 ,already ,mr4 ,a4 ,h>k] ( ! ,geological ,survey1 :o is engag$ 9 mapp+ ! int]e/+ & complicat$ di/rict ( ,/ra? 9 ,skye1 has obs]v$ t ! dykes :i* are old] ?an ! great granophyre bosses ( t tract may be di/+ui%$ f ^? :i* are lat] ?an ^! protrusions4 ,! old] basic dykes are n conspicu\sly porphyritic1 are frequ5tly m>k$ by a close-gra9$ m>g9 or ev5 ) a v5e] ( basalt-glass1 sometimes h an incl9ation ( z mu* z #de1 are occasionally discont9u\s1 & n infrequ5tly bran* or s5d out ve9s4 ,! y\ng] dykes1 on ! o!r h&1 z w be m p>ticul>ly notic$ 9 ! foll[+ *apt]1 are di/+ui%$ by ! frequ5t & rem>kable "* ( _! porphyritic inclusions1 by ! pres5ce ( =eign fragm5ts 9 !m1 by ! great] p]fection ( _! jo9t+1 & by _! seldom dep>t+ mu* f ! v]tical4#afc ,!y are likewise (t5 m>k$ly acid 9 composition1 includ+ su* rocks z granophyre1 felsite & pit*/one4 ,footnote #afc3 ,9 ! ,bla? ,bhe9n gr\p ( gabbro-hills1 h[ev]1 x is ! y\nge/ dykes :i* h be5 f\nd by ,mr4 ,h>k] to possess ! l[e/ hade4 7#a7 ,ext]nal ,*>act]s4--,z reg>ds ! gra9 ( ! rock1 e gradation may be f\nd1 f a co>sely cry/all9e mass1 9 :i* ! compon5t m9]als are di/9ctly traceable ) ! nak$ eye1 to a black lu/r\s basalt-glass4 ,ea* dyke g5]ally pres]ves ! same "* ?r\gh\t its ext5t4 ,z a rule1 broad & long dykes are co>s] 9 gra9 ?an n>r[ & %ort ones4 ,= ! mo/ "p1 !re runs along ea* side ( a dyke a selvage ( f9] gra9 ?an ! re/ ( ! mass4 ,?is m>g9al /rip v>ies 9 bread? f an in* or less up to a foot or m1 & obvi\sly owes its orig9 to ! m rapid *ill+ ( ! molt5 rock along ! walls ( ! fissure4 ,x usually %ades away inp]ceptibly into ! l>g]-gra9$ inn] portion4 ,ev5 ) ! nak$ eye its compon5t mat]ials c be se5 to be m f9ely cry/all9e ?an ! re/ ( ! dyke1 ?\gh :]e disp]s$ porphyritic felsp>s occur !y are z l>ge 9 ! m>g9al /rip z 9 any o!r "p ( a dyke1 = !y belong to an e>li] p]iod ( cry/allization ?an ! small] felsp>s ( ! gr\ndmass & 7 already float+ 9 ! magma :ile x 0 /ill 9 a molt5 /ate4 ,?is f9]-gra9$ ext]nal b&1 s di/9ctive ( an eruptive & inject$ rock1 is ( great s]vice 9 enabl+ u to trace dykes :5 !y trav]se o!r dykes or masses ( igne\s rock ( simil> *>act]s to _! own4 ,:5 "o dyke crosses ano!r1 t :i* has its m>g9al b& ( f9] gra9 unbrok5 mu/ obvi\sly be ! y\ng] ( ! two4 ,illu/ration3 ,fig4 #bce4--,plan ( basalt-ve9s ) selvages ( black basalt-glass1 ea/ side ( ,be9n ,tighe1 ,isle ( ,eigg4 ,b 9 _m examples 9 ! s\? ( ,scotl&1 ,argyle%ire & ! ,inn] ,hebrides1 ! f95ess ( gra9 ( ! out] b& culm9ates 9 a p]fect volcanic glass4 ,:]e ?is occurs1 ! glass is usually jet black1 m r>ely gre5i% or blui% black 9 t9t1 & v>ies 9 ?ickness f ab\t a c\ple ( in*es to a m]e v>ni%-l film on ! out] face ( ! dyke1 ! av]age wid? be+ probably less ?an a qu>t] ( an in* 7,fig4 #bce74 ,on _! wea!r$ surface ^! ext]nal glassy lay]s g5]ally pres5t a patt]n ( r\nd$ or polygonal prom95ces1 v>y+ up to f\r or five l9es or ev5 m 9 diamet]1 & sep>at$ by depressions or n>r[ ribs4 ,! transition f ! glass to ! cry/all9e "p ( ! m>g9al f9e-gra9$ /rip is usually some:at abrupt1 insomu* t on wea!r$ faces x is (t5 difficult to get good specim5s1 ow+ to ! t5d5cy ( ! vitre\s portion to fly (f :5 /ruck ) ! hamm]4 ,! glass d\btless repres5ts ! orig9al condition ( ! rock ( ! dyke4 ,x 0 sudd5ly *ill$ & solidifi$ by contact ) ! cold walls ( ! fissure4 ,inside ?is ext]nal glassy coat+1 ! molt5 mat]ial c\ld probably /ill move1 & _h "t to assume a m or less completely cry/all9e condition be=e solidification4 ,n infrequ5tly ! glass %[s sph]ulitic =ms1 visible to ! nak$ eye1 & likewise a m or less di/9ctly develop$ p]litic /ructure4 ,^! features1 h[ev]1 are be/ /udi$ 9 ?9 sections ( ! rock ) ! aid ( ! microscope1 z w be subsequ5tly ref]r$ to4 ,9 "s dykes1 ! glass is n conf9$ to ! edges1 b runs 9 /r+s or broad] b&s along ! c5tral portions1 or has be5 squeez$ into little cavities l /eam-holes or into m9ute fissures4 ,"o ( ! mo/ rem>kable examples ( ?is peculi>ity occurs 9 ! well-kn[n dyke ( ,eskdale1 :i* runs = s _m miles across ! s\!rn upl&s ( ,scotl&4#afd ,?is dyke ?r\gh\t mo/ ( its c\rse is a cry/all9e rock ( ! &esitic type4 ,at ,wat ,c>rick1 9 ,eskdale1 x pres5ts an arrangem5t into ?ree p>allel b&s4 ,on ei!r side1 a zone ab\t eight feet broad consi/s ( ! usual cry/all9e mat]ial4 ,betwe5 ^! two m>g9al portions lies an int]calat$ mass #af to #ah feet broad1 ( a v compact & m or less vitre\s rock4 ,! dem>cation betwe5 ?is c5tral b& & ! m cry/all9e zones ( ! outside is q %>p1 & ! two k9ds ( rock %[ a totally di/9ct sy/em ( jo9t+4 ,!re c1 !re=e1 be little d\bt t ! glassy c5tre belongs to a lat] uprise ?an ! out] portions1 ?\gh possibly x may /ill h be5 includ$ 9 ! long process ( solidification ( "o orig9al inject$ mass ( molt5 mat]ial4 ,if ! m>g9al p>ts adh]$ firmly to ! walls1 ! c5tre1 :i* ) its b& ( vesicles seems (t5 to h be5 a l9e ( weakness1 might be ruptur$ & subsequ5t intrusions w\ld f9d _! way along ! r5t4 ,examples ( ?is splitt+ ( dykes ) ! intrusion ( lat] eruptive ,mat]ial w be cit$ 9 lat] pages4 ,footnote #afd3 ,see ,proc4 ,roy4 ,phys4 ,soc4 ,ed94 v4 7#ahhj71 p4 #bda4 ,mr4 ,cl\gh1 :ile mapp+ = ! ,geological ,survey ! extraord9>ily num]\s dykes 9 ! ea/]n "p ( ,argyle%ire betwe5 ! ,fir? ( ,clyde & ,upp] ,lo* ,fyne1 obs]v$ six or sev5 examples ( dykes %[+ glassy b&s 9 _! c5tres1 ) *>act]s simil> to ^? ( ! ,eskdale dyke4 ,he f\nd an abs5ce ( def9ite & regul> jo9ts 9 ! c5tral glassy b&1 & on ! o!r h&1 an irregul> set ( divisional planes by :i* ! rock is trav]s$1 & :i* he comp>$ to ^? se5 9 true p]litic /ructure4 ,:ile1 z a g5]al rule1 ! ext]nal portions ( a dyke are clos]-gra9$ ?an ! c5tre1 r>e cases occur :]e ! middle is ! mo/ f9ely cry/all9e "p4 ,i am dispos$ to reg>d ^! cases & ! glassy c5tres z =m+ 9 reality no true exceptions to ! rule1 t ! out] portions ( a dyke consolidat$ fir/1 & are !re=e f9e/ 9 texture4 ,= ! mo/ "p1 ea* dyke appe>s to be due to a s+le uprise ( molt5 matt]1 ?\gh consid]able movem5ts may h tak5 place )9 its mass be=e ! :ole /iff5$ into /one4 ,"s p>ticul>s reg>d+ ^! movem5ts w be giv5 9 section #ab ( ! next ,*apt]4 ,x has already be5 m5tion$ t 9 l>ge dykes :i* h s]v$ z volcanic pipes1 x is conceivable t :ile ! mat]ial next ! outside consolidat$ & adh]$ to ! walls1 ! c5tral portion may h rema9$ liquid1 & may ev5 h be5 propell$ upw>d & h be5 succe$$ by a diff]5t k9d ( magma1 z has be5 sugge/$ by ,mr4 ,idd+s4 ,9 su* cases1 :i*1 if !y occur1 are probably excessively r>e1 we may expect t ! e>li] & lat] mat]ial w n be %>ply m>k$ (f f ea* o!r1 unless we suppose t ! :ole ( ! e>li] liquid magma 0 s entirely eject$ t only its congeal$ m>g9al selvage 0 left z b\nd+ walls = ! new] injection4 ,:]e1 aft] m or less complete consolidation _h tak5 place1 ! fissure op5$ aga91 or f any o!r cause ! dyke 0 split along its c5tre1 any lava :i* rose up ! r5t w\ld t5d to take a f9] gra9 ?an ! mat]ial ( ! re/ ( ! dyke1 & might ev5 solidify z glass4 ,l>ge scatt]$ cry/als ( felsp>1 ( an e>li] consolidation ?an t ( ! m9ut] =ms ( ! same m9]al 9 ! g5]al gr\ndmass ( ! rock1 give a porphyritic /ructure & &esitic "* to _m dykes4 ,occasionally su* cry/als atta9 a consid]able size4 ,mr4 ,cl\gh has obs]v$ !m 9 "s ( ! ,argyle%ire dykes rea*+ a l5g? ( betwe5 ?ree & f\r in*es1 ) a ?ickness ( two in*es4 ,sometimes !y are di/ribut$ ) tol]able uni=mity ?r\gh ! sub/ance ( ! dyke4 ,b n infrequ5tly !y may be obs]v$ 9 m or less def9ite b&s p>allel ) ! b\nd>y walls4 ,unlike ! y\ng] la?-%ap$ & mu* small] felsp>s ( ! gr\ndmass1 !y %[ no dim9ution ei!r 9 size or abundance t[>ds ! edge ( ! dyke4 ,on ! contr>y1 z already m5tion$1 !y are (t5 conspicu\s 9 ! close-gra9$ m>g9al /rip1 & may be f\nd ev5 9 ! glassy selvage1 or t\*+ ! v wall ( ! fissure4 ,inde$1 !y are sometimes m abundant 9 ! out] ?an 9 ! inn] portions ( a dyke1 hav+ travell$ outw>ds to ! surfaces ( e>lie/ cool+ & cry/allization4 ,mr4 ,cl\gh has giv5 me ! details ( an int]e/+ case ( ?is k9d obs]v$ by him 9 ,gl5 ,t>san1 ,ea/]n ,argyle%ire3--,= an in* or s f ! edge ( ?is dyke1 he rem>ks1 porphyritic felsp>s giv+ squ>i% sections1 & rang+ up to "o-?ird ( an in* 9 l5g?1 are s abundant z ne>ly to equal 9 bulk ! surr\nd+ gr\ndmass4 ,= ! next in* & a half1 !y are decid$ly few]1 occupy+ p]haps h>dly an eigh? ( ! area expos$4 ,!n = a bread? ( ?ree in*es !y come 9 aga9 ne>ly z abundantly z at ! sides2 aft] :i* !y dim9i% ?r\gh a b& #bg in*es broad1 :]e !y may =m f #a_/h to #a_/ab ( ! rock4 ,he f\nd ano!r case :]e1 9 a dyke sev]al y>ds wide1 porphyritic felsp>s1 sometimes an in* long1 are common along ! ea/]n m>g9 ( ! dyke 9 a b& ab\t two in*es broad1 b ne>ly abs5t f ! re/ ( ! rock4 ,else:]e ! cry/als are gr\p$ r 9 pat*es ?an 9 b&s4 ,among ! dykes s\? ( ,oban "s simil> in/ances ( co>sely porphyritic felsp>s may be obs]v$4 ,n only are ^! porphyritic felsp>s apt to occur 9 b&s p>allel ) ! out] m>g9s ( ! dykes1 b !y t5d to range !mselves ) _! long] axis 9 ! same direction1 ?us ev5 on a l>ge scale1 visible at "s di/ance1 %[+ ! fl[-/ructure1 :i* is s (t5 errone\sly reg>d$ z ess5tially a microscopic arrangem5t1 & z specially *>act]i/ic ( sup]ficial lava-/reams4 ,mr4 ,h>k] 9 8 survey ( ,/ra?1 ,skye1 has met ) "s rem>kable examples ( ! enclosure & incorporation ( =eign mat]ials 9 ! y\ng] gr\p ( dykes :i* 9 t di/rict trav]se ! granophyres & gabbros4 ,he rem>ks t ! great majority ( ^! dykes are basic1 & he has f\nd !m to be capable ( conv5i5t division into two gr\ps4 #a/1 ,non-porphyritic basic dykes ) a specific gravity betwe5 #bhg & #big1 & an amygdaloidal /ructure af=d+ cle> indication ( fl[+ movem5t1 ei!r at ! sides or along a c5tral b&4 ,^! dykes d n greatly diff] f ^? ( pre-granophyre eruption4 #bnd1 ,porphyritic basic dykes :i* pres5t features ( peculi> int]e/4 ,! porphyritic 7or pseudo-porphyritic7 elem5ts1 accord+ to ,mr4 ,h>k]'s obs]vations1 are con/antly felsp>1 frequ5tly subord9ate augite1 & exceptionally qu>tz4 ,! felsp>s h = ! mo/ "p r\nd$ outl9es ) a bord]+ zone ( glass cavities app>5tly ( second>y orig94 ,! augite1 9 r\nd$ composite cry/al-gra9s1 diff]s f t ( ! gr\ndmass & resembles ! augite ( ! gabbros4 ,! qu>tz-gra9s are likewise r\nd$1 & %[ sometimes a di/9ct corrod$ bord]4 ,^! *>act]s1 ,mr4 ,h>k] obs]ves1 are ^? ( cry/als d]iv$ f "s =eign s\rce1 & x c sc>cely be d\bt$ t ?is is ! explanation ( _! pres5ce4 ,he notic$ t ! dykes 9 "q frequ5tly enclose fragm5ts1 v>y+ up to sev]al in*es 9 diamet]1 ( gabbro1 granite or granophyre1 b$d$ lava1 qu>tzite1 etc41 :i* %[ cle> evid5ce ( hav+ be5 r\nd$ & corrod$ by an envelop+ magma1 & recognizable cry/als f "s ( ! fragm5ts may be obs]v$ 9 ! surr\nd+ p>ts ( ! matrix ( ! dykes4 ,mo/ ( ! felsp> & augite cry/als dissem9at$ ?r\gh ^! porphyritic basic dykes may be ref]r$ to ! p>tial reabsorption ( enclos$ fragm5ts ( gabbro4 ,! same obs]v] has f\nd t _m ( ! dykes :i* rise ?r\gh ! basalt-plateau ( ,/ra?aird are cr[d$ ) gabbro fragm5ts4 ,ano!r megascopic "* ( ! mat]ial compos+ ! dykes is ! frequ5t pres5ce ( amygdales4 ,x has sometimes be5 suppos$ t amygdaloidal /ructure may be reli$ ^u z a te/ to di/+ui% a mass ( molt5 rock :i* has rea*$ ! surface f "o :i* has consolidat$ "u consid]able pressure bel[ gr\nd4 ,t ?is supposition1 h[ev]1 is errone\s is demon/rat$ by hundr$s ( dykes 9 ! great sy/em :i* ,i am n[ describ+4 ,b ! amygdales ( a dyke (f] c]ta9 peculi>ities :i* s]ve 9 a g5]al way to m>k !m (f f ^? ( an outfl[+ lava4 ,!y are usually small] & m uni=m 9 size ?an 9 ! latt] rock4 ,!y are also m regul>ly sph]ical & less frequ5tly elongat$ 9 ! direction ( fl[4 ,moreov]1 !y are n usually di/ribut$ ?r\gh ! :ole bread? ( a dyke1 b t5d to arrange !mselves 9 l9es especially t[>ds its c5tre 7,fig4 #bcf74 ,9 ^! c5tral b&s ! cavities are l>ge/ & dep>t f>!/ f ! regul> sph]ical =m1 s t = %ort spaces !y may equal 9 bulk ! mass ( enclos+ rock4 ,9 "s r>e in/ances1 a :ole dyke is compos$ ( cellul> basalt1 l "o ( ! lava-%eets 9 ! plateaux1 z may be se5 on ! nor? flank ( ,be9n ,su>dal1 ,skye4 ,mr4 ,h>k] has obs]v$ t an amygdaloidal /ructure is m common among ! e>li] ?an among ! lat] dykes ( t di/rict4 ,illu/ration3 ,fig4 #bcf4--;,arrangem5t ( l9es ( amygdales 9 a dyke1 ,/ra?more1 ,skye4 ,besides ! common arrangem5t ( f9e-gra9$ edges & a m co>sely cry/all9e c5tre1 in/ances are f\nd :]e "o ( ! contra/$ portions ( a dyke trav]ses ! o!r 9 ! =m ( ve9s4 ,( ^!1 ,i ?9k1 !re are two di/9ct k9ds1 probably orig9at+ 9 entirely diff]5t conditions4 ,9 ! fir/ place1 !y may be ( co>s] gra9 ?an ! re/ ( ! rock2 b su* a /ructure appe>s to be ( extremely r>e occurr5ce4 ,i h notic$ "s examples on ! coa/ ( ,r5frew%ire1 :]e /r+s ( a m co>sely cry/all9e texture trav]se ! f9]-gra9$ body ( ! rock4 ,ve9s ( ?is k9d are probably ( ! same nature z ! s-call$ segregation-ve9s1 to be aft]w>ds ref]r$ to z ( frequ5t occurr5ce among ! ?ick] ,t]ti>y sills4 ,!y consi/ ( ! same m9]als z ! re/ ( ! rock1 b 9 a diff]5t & m develop$ cry/all9e arrangem5t1 & !y conta9 no glassy or devitrifi$ mat]ial1 except su* portions ( t ( ! surr\nd+ gr\ndmass z may h be5 caught betwe5 _! cry/all9e con/itu5ts4 ,! second k9d ( ve9s1 :i*1 ?\gh n common1 is ( mu* m frequ5t occurr5ce ?an ! fir/1 is m p>ticul>ly to be met ) among ! broad] dykes1 & is di/+ui%$ by a rem>kable f95ess ( gra91 sometimes approa*+ ! texture ( felsite or jasp]1 & occasionally tak+ ! =m ( actual glass4 ,su* ve9s v>y f half an in* or less1 up to f\r or five in*es 9 bread?4 ,!y run sometimes p>allel ) ! walls ( ! dyke1 b (t5 irregul>ly 9 all directions1 & = ! mo/ "p avoid ! m>g9al portions1 ?\gh n[ & !n com+ up to ! edge4 ,!y nev] ext5d beyond ! body ( ! dyke itself into ! surr\nd+ rock4 ,?\gh !y h obvi\sly be5 inject$ aft] ! solidification ( ! rock :i* !y trav]se1 !y may q possibly be extrusions ( a deep] unconsolidat$ portion ( ! same rock into r5ts ( ! already /iff5$ ov]ly+ p>ts4 ,! field-geologi/ _c fail to be /ruck ) ! mu* great] h>dness ( ^! f9e-gra9$ ve9s & /r+s t ramify ?r\gh ! co>sely cry/all9e dol]ite1 &esite or o!r v>iety ( ! broad] dykes4 ,he c readily p]ceive 9 _m cases _! m silice\s composition1 & ! inf]5ces he d$uces f ! r\gh obs]vations he c make 9 ! field are confirm$ by ! results ( *emical analysis 7see p4 #acg74 ,9 connection ) ve9s ( f9] mat]ial1 t may belong to a late /age ( ! consolidation ( ! g5]al body ( a dyke1 ref]5ce may be made "h to ! occasional occurr5ce ( pat*es ( an exce$+ly compact or homog5e\s texture imm]s$ 9 ! usual f9ely cry/all9e m>g9al mat]ial4 ,!y look l angul> & subangul> portions ( ! m rapidly cool$ out] edge1 :i* h be5 brok5 (f & c>ri$ upw>d by ! /ill mov+ mass 9 ! fissure4#afe ,footnote #afe3 ,see ,mr4 ,j4 ,j4 ,h4 ,teall1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 7#ahhd71 p4 #bad4 ,9 g5]al1 ea* dyke is compos$ ( "o k9d ( rock1 & reta9s its *emical & m9]alogical *>act]s ) s+ul> p]si/5ce4 ,! diff]5ce ( texture betwe5 ! f9e-gra9$ *ill$ m>g91 ) its occasional glassy coat+1 & ! m co>sely cry/all9e c5tre is due to cool+ & cry/all9e segregation 9 :at 0 no d\bt orig9ally "o tol]ably uni=m molt5 mass4 ,! glassy c5tral b&s1 too1 ?\gh !y indicate a rupture ( ! dyke up ! middle1 may at ! same "t q conceivably be1 z ,i h said1 extrusions f a l[] portion ( ! dyke be=e ! f9al solidification ( ! :ole4 ,! ramify+ ve9s ( f9] gra9 t n[ & !n trav]se "o ( ! l>ge dykes are likewise explicable z p>ts ( a /age t[>ds entire consolidation4 ,all ^! vitre\s portions1 :e!r /ill rema9+ z glass or hav+ und]gone devitrification1 are m acid ?an ! surr\nd+ cry/all9e p>ts ( ! rock4 ,!y repres5t ! silice\s "m-liquor1 s to speak1 :i* 0 left aft] ! sep>ation f x ( ! cry/alliz$ m9]als1 & :i*1 p]haps1 entangl$ "h & !re 9 vesicles ( ! sl[ly cool+ & consolidat+ rock1 0 ready to be =c$ up into cracks ( ! ov]ly+ mass dur+ any r5ewal ( t]re/rial di/urbance4 ,b examples occur :]e a dyke1 in/ead ( consi/+ ( "o rock1 is made up ( two or m b&s ( rock :i*1 ev5 if !y resemble ea* o!r closely1 c be %[n to be ! results ( sep>ate eruptions4 ,^!1 :i* are obvi\sly n exceptions to ! g5]al rule ( ! homog5eity ( dykes1 ,i w consid] 9 ! next ,*apt]4 ,among ! petrographical v>ieties obs]vable 9 ! field is ! occasional envelopm5t ( portions ( ! surr\nd+ rocks 9 ! body ( a dyke4 ,angul> fragm5ts torn (f f ! fissure-walls h be5 c>ri$ upw>ds 9 ! asc5d+ lava1 & n[ appe> m or less metamorphos$1 ! am\nt ( alt]ation seem+ to dep5d *iefly ^u ! susceptibility ( ! enclos$ rock to *ange f ! effects ( heat4 ,cases ( su* entanglem5t1 h[ev]1 are ( less common occurr5ce ?an ^? already ref]r$ to1 :]e pieces ( "s deep-seat$ rock1 su* z ! gabbros ( ,skye1 h be5 c>ri$ up 9 ! asc5d+ magma4 ,occasionally1 :]e ! enclos$ fragm5ts are oblong1 !y are arrang$ ) _! long] axes p>allel to ! walls ( ! dyke1 %[+ fl[-/ructure on a l>ge scale4 ,mr4 ,cl\gh has f\nd "s dykes ne> ,dunoon :i* enclose fragm5ts ( s*i/ ne>ly ?ree feet 9 l5g?4 ,"o ( ! mo/ int]e/+ ( ! megascopic features ( ! dykes is ! jo9ts by :i* !y are trav]s$4 ,^! divisional planes are no d\bt to be reg>d$ z consequ5ces ( ! contraction ( ! orig9al molt5 rock dur+ cool+ & consolidation betwe5 its fissure-walls4 ,!y are ( consid]able int]e/ & importance1 inasmu* z !y furni% a ready means ( trac+ a dyke :5 x runs ?r\gh rock ( ! same nature z itself1 & also help to ?r[ "s light on ! /ages 9 ! consolidation ( ! mat]ial ( ! dyke4 ,illu/ration3 ,fig4 #bcg4--,sy/ems ( jo9ts 9 ! dykes4 a1 p>allel2 b1 transv]se4 ,two di/9ct sy/ems ( jo9ts are recognizable 7,fig #bcg74 ,?\gh sometimes comb9$ 9 ! same dyke1 !y are mo/ conspicu\sly display$ :5 ea* occurs1 z x g5]ally does1 by itself4 ,! fir/ & less frequ5t sy/em ( jo9ts 7a7 has be5 det]m9$ by l9es ( retreat1 :i* are p>allel to ! walls ( ! dyke4 ,! jo9ts are !n close/ toge!r at ! m>g91 & may be few or altoge!r abs5t 9 ! c5tre4 ,!y are sometimes s num]\s1 p>allel & def9$ t[>ds ! bord]s ( ! dyke1 z to split ! rock up into ?9 flags4 ,:]e transv]se jo9ts are also pres5t ^! flags are divid$ into irregul> tess]4 ,9 ! second or transv]se sy/em ( jo9ts 7b71 :i* is ! m usual1 ! divisional l9es pass across ! bread? ( ! dyke1 ei!r completely f side to side1 or f "o wall = a long] or %ort] di/ance t[>ds ! o!r4 ,:]e ?is s]ies ( jo9ts is mo/ completely develop$ ! dyke appe>s to be built up ( prisms pil$ horizontally1 or ne>ly s1 "o above ano!r4 ,^! prisms1 9 r>e in/ances1 are z regul> z ! columns ( a basalt-%eet 7see ,fig4 #aff74 ,usually1 h[ev]1 !y h irregul>ly def9$ faces1 & m]ge into ea* o!r4 ,:]e ! prismatic /ructure is n display$1 ! jo9ts1 />t+ %>ply at ! wall ( ! dyke1 /rike inw>ds 9 irregul> curv+ l9es4 ,x is su* transv]se jo9ts t enable ! eye1 ev5 f a di/ance1 to di/+ui% readily ! c\rse ( a dyke up ! face ( a cliff ( basalt-b$s1 = !y belong to ! dyke itself1 are (t5 at "r angles to ^? ( ! adjac5t basalt1 & by _! alt]nate project+ & re-ent]+ angles seam ! dyke ) p>allel b>s ( light & %ade 7see ! d\ble dyke 9 ,fig4 #ccc74 ,:]e !y trav]se n only ! g5]al mass ( a dyke1 b also ! contemporane\s ve9s :i* cross x1 x may be inf]r$ t ^! ve9s 7 inject$ be=e ! f9al solidification & contraction ( ! :ole dyke4 ,illu/ration3 ,fig4 #bch4--,section ( cyl9drical ve9 or dyke1 cutt+ ! b$d$ lavas1 ea/ side ( ,fugl1 ,f>oe ,isl&s4 ,an int]e/+ modification ( ! transv]se jo9ts may sometimes be obs]v$1 :]e1 z 9 ! case ( ! ,palozoic ,rock & ,sp9dle1 at ,/4 ,&rews 7,fig4 #bbb71 ! molt5 mat]ial has solidifi$ 9 a tubul> or sph]ical cavity4 ,! jo9ts !n radiate inw>ds f ! out] curv$ surface4 ,! mo/ rem>kable in/ance ( ?is /ructure :i* ,i h f\nd among ! ,t]ti>y volcanic plateaux occurs on ! ea/ side ( ! isl& ,fugl1 ! mo/ nor?-ea/]ly ( ! gr\p ( ! ,f>oes4 ,x is cut 9 section by ! face ( ! precipice1 :]e x appe>s z a r\nd mass ab\t #dj or #ej feet 9 diamet] pi]c+ ! plateau-basalts4 ,a selvage ( f9] mat]ial r\nd its out] edge %[s ! effect ( rapid *ill+1 :ile ! jo9ts div]ge f ! p]iph]y & ext5d 9 fan-%ape t[>ds ! c5tre 7,fig4 #bch74 ,illu/ration3 ,fig4 #bci4--;,jo9t-/ructures 9 ! c5tral vitre\s portion ( ! ,eskdale ,dyke 7,b4 ,n4 ,pea*74 ,a1 ,view ( a squ>e y>d ( ! out] wall ( ! vitre\s c5tral b&1 %[+ ! polygonal arrangem5t ( ! prisms & _! inve/+ %ea? ( ribs4 ,b1 ,view ( a small] portion ( ! same wall to %[ ! detail$ /ructure ( ! ribs 7a a7 & _! vitre\s cores 7b b74 ,c1 ,pr(ile ( a "p ( ! wea!r$ face ( ! wall1 %[+ ! way 9 :i* ! h>d ribs or %ea?s project at ! surface4 ,"o ( ! mo/ rem>kable exhibitions ( jo9t-/ructure hi!rto notic$ among ! ,t]ti>y dykes is t :i* occurs 9 ! c5tral vitre\s b& ( ! ,eskdale dyke already ref]r$ to4 ,! rock is divid$ into ne>ly horizontal prisms1 ea* ( :i* consi/s ( an inn] m vitre\s core & an out] m li?oid %ea?4 ,by ! coh]5ce ( _! polygonal & irregul> faces1 & ! great] durability ( _! mat]ial1 ^! %ea?s project on ! wea!r$ wall ( ! vitre\s c5tre ( ! dyke 9 a curi\sly reticulat$ gr\p+ ( prom95t ribs ea* ab\t two in*es broad 7,fig4 #bci1 ,a71 :ile ! vitre\s cores1 be+ m readily act$ on by ! wea!r1 are holl[$ out into little cup-%ap$ depressions4 ,ea* rib is ?us compos$ ( ! %ea?s or out] li?oid portions ( two prisms1 ! l9e ( sep>ation be+ m>k$ by a suture along ! c5tre 7,b74 ,betwe5 ?is m$ian suture & ! inn] glassy core ! rib is fur!r cut into small segm5ts by a set ( close jo9ts1 :i* are plac$ g5]ally at "r angles to ! c\rse ( ! rib 7,c74 ,exam9$ ) a l5s1 ! li?oid sub/ance ( ^! %ea?s has a dull f9ely granul> aspect1 l t ( felsitic rocks1 ) scatt]$ felsp>s4 ,x is obvi\sly a m devitrifi$ condition ( ! mat]ial :i* =ms ! core ( ea* prism4 ,?is mat]ial pres5ts on a fre% fracture a deep iron-black col\r1 dull res9\s lu/re & vitre\s texture4 ,x at once recalls ! aspect ( _m acid pit*/ones1 & 9 ! e>ly days ( petrography 0 naturally mi/ak5 = "o ( ^! rocks4 ,?r\gh its sub/ance num]\s k]nels ( m glassy lu/re are disp]s$1 ea* ( :i* usually conta9s "o or m amygdales ( dull :ite *alc$ony1 b sometimes only an empty black cavity4 ,^! black gli/5+ k]nels ( glass1 ( all sizes up to t ( a small bean1 scatt]$ ?r\gh ! dull res9\s matrix1 =m ) ! :ite amygdales ! mo/ prom95t feature 9 ! cores2 b cry/als ( felsp>s may also be obs]v$4 ,"s details ( ! microscopic *>act]s ( ?is rem>kable /ructure w be giv5 9 a subsequ5t page4 ,! relation ( ! cores & %ea?s to ! prismatic jo9t+ ( ! rock seems to %[ t devitrification _h n be5 complet$ :5 ^! jo9ts 7 e/abli%$1 & t x proce$$ f ! faces ( ea* prism inw>ds4 7#b7 ,microscopic ,*>act]s4--,mu* in=mation has n[ be5 obta9$ reg>d+ ! microscopic /ructure ( ! basaltic1 dol]itic & &esitic dykes4 ,! cry/all9e *>act]s ( ^? 9 ! ,nor? ( ,engl& h be5 /udi$ by ,mr4 ,teall1#aff & "s ( ^? f ! ,we/ ( ,scotl& h be5 inve/igat$ by ,pr(essors ,judd & ,cole4#afg ,tak5 z a :ole1 ! rocks compos+ ! dykes are f\nd1 :5 exam9$ microscopically1 to consi/ ess5tially ( mixtures ( a plagioclase felsp>1 pyrox5e & iron oxide1 ) or )\t oliv9e1 & usually ) m or less int]/itial matt]4 ,footnote #aff3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xl4 7#ahhd74 ,footnote #afg3 ,op4 cit4 vol4 xxxix4 7#ahhc7 p4 #ddd 7basalt-glass72 xlii4 7#ahhf7 p4 #di1 :]e ,pr(essor ,judd discusses ! gabbros1 dol]ites & basalts z a :ole4 ,! felsp> appe>s to be 9 "s cases labradorite1 9 o!rs anor?ite1 b !re may be a m+l+ ( sev]al species 9 _m ( ! dykes1 z 9 ! augite-&esite ( ! ,santor9 eruption 9 #ahff1 :]e9 ,pr(essor ,f\qu f\nd t ! l>g] porphyritic felsp>s 7 ma9ly labradorite1 b p>tly anor?ite1 :ile ^? ( ! gr\ndmass 7 microlites ( albite & oligoclase4#afh ,! l>ge felsp>s scatt]$ porphyritically ?r\gh ! gr\ndmass are evid5tly ! result ( an e>ly consolidation1 unless :]e !y are survivals f fragm5ts ( old] porphyritic rocks :i* h be5 envelop$ & p>tially dissolv$ 9 ! dykes4 ,!y are (t5 crack$1 p5etrat$ by ! gr\ndmass1 or ev5 brok5 into fragm5ts1 & h corrod$ bord]s4 ,!y sometimes include portions ( ! gr\ndmass1 & pres5t ! zonal gr[? /ructure 9 great p]fection4 ,! small felsp>s ( ! gr\ndmass1 on ! o!r h&1 are z obvi\sly ! result ( a lat] cry/allization1 = !y v>y 9 size & cry/allographic developm5t accord+ to _! position 9 ! dyke4 ,^? f ! c5tre are (t5 9 well-=m$ cry/als1 :i* sometimes pass r\nd _! bord]s into acicul> microlites4 ,^? 9 ! m>g9al p>ts ( ! dyke occur *iefly 9 ! =m ( ^! microlites1 =m+ ! felt$ aggregate s *>act]i/ic ( ! &esites4 ,curi\s skeleton =ms1 compos$ ( aggregates ( microlites1 connect ! latt] ) ! m completely develop$ cry/als1 & illu/rate ! mode ( cry/allization ( ! felspa?ic con/itu5ts ( ! dykes4#afi ,footnote #afh3 ,santor9 et ses ruptions1 #ahgi1 p4 #bjc4 ,footnote #afi3 ,see ,mr4 ,teall's excell5t description ( ! ,clevel& dyke1 9 ! pap] above cit$4 ,! pyrox5e is probably 9 mo/ cases monocl9ic 7black or common augite71 b is sometimes rhombic 7usually en/atite1 less frequ5tly p]haps hyp]/h5e74 ,x occurs 9 7a7 well-develop$ cry/als1 7b7 cry/all9e masses ) "s ( ! faces ( ! cry/als develop$1 7c7 granul> aggregates :i* pol>ise 9 "o plane1 7d7 sep>ate granules & microscopic microlites1 :i* may be sph]ical 7globulites7 or oblong 7longulites74 ,! black iron-oxide is sometimes magnetite1 sometimes ilm5ite1 or o!r titanif]\s ore4 ,apatite n infrequ5tly occurs among ! orig9al con/itu5ts4 ,oliv9e is entirely abs5t f mo/ ( ! l>ge solit>y dykes1 especially at a di/ance f ! great volcanic c5tres1 & no s]p5t9\s matt] rema9s to indicate t x 0 ev] pres5t 9 !m4 ,b x is to be met ) 9 num]\s basalt-dykes 9 ! volcanic areas1 ei!r 9 sp>sely scatt]$ or 9 tol]ably abundant cry/als4 ,biotite occasionally appe>s4 ,among ! second>y products1 calcite & pyrites are d\btless ! mo/ common4 ,to ^! mu/ be add$ qu>tz1 *alc$ony & v>i\s zeolitic sub/ances1 besides ! aggregates :i* result f ! decomposition ( ! f]ro-magnesian con/itu5ts & ! oxidation ( ! f]r\s oxides4 ,9 _m dykes !re is little or no int]/itial matt] betwe5 ! cry/all9e con/itu5ts ( ! gr\ndmass4 ,9 o!rs ?is matt] am\nts to a half or m ( ! :ole composition1 & f su* cases a s]ies ( gradations may be trac$ into a complete glass conta9+ only ! rudim5t>y =ms ( cry/als 7globulites1 longulites1 etc471 ) scatt]$ porphyritic cry/als ( an e>li] consolidation4 ,! process ( ! disappe>ance ( ?is orig9al glass may be admirably /udi$ 9 _m dykes4 ,at ! out] wall1 ! glass rema9s ne>ly z x 0 :5 contact ) ! cold walls ( ! fissure solidifi$ x4 ,f t ext]nal vitre\s lay] ! successive devitrification products & cry/all9e gr[?s may be foll[$ inw>ds until 9 ! c5tral p>ts ( a broad dyke little or no trace ( ! int]/itial matt] may be left4 ,illu/ration3 ,fig4 #bdj4--,microscopic /ructure ( ! vitre\s "p ( ! ,eskdale ,dyke4 ,?is section %[s a cry/al ( augite1 enclos+ magnetite & surr\nd$ ) microlites1 ea* ( :i* consi/s ( a c5tral pale yell[ rod cru/$ ) pale yell[ isotropic globulites4 ,! glass ar\nd ?is aggregation is cle>1 b at a little di/ance globulites 7_m ( !m elongat$ & di*otom\s7 ab\nd1 ) "h & !re scatt]$ microlites1 "s ( :i* are curv$ & spiral4 7#hjj diamet]s47#agj ,footnote #agj3 ,proc4 ,roy4 ,phys4 ,soc4 ,ed94 v4 7#ahhj71 p4 #bee4 ,! mo/ in/ructive example ( ! process ( devitrification :i* has come "u my obs]vation occurs 9 ! ,eskdale dyke4 ,! c5tral cores already ref]r$ to pres5t a true glass1 :i* 9 ?9 sections is p]fectly transp>5t & almo/ col\rless1 b by /reaks & curv+ l9es ( d>k] t9t %[s beautiful fl[-/ructure4 ,! devitrification ( ?is glass has be5 accompli%$ by ! developm5t ( cry/allites & cry/als1 :i* increase 9 numb] until all ! vitre\s "p ( ! rock disappe>s4 ,:at seems "u a l[ p[] to be a /ructureless or slightly du/y glass c be resolv$ ) a high] objective into an aggregate ( m9ute globules or granules 7globulites71 :i* av]age p]haps #a_/bj1jjj ( an in* 9 diamet]4 ,"s ( ^! bodies are elongat$ & ev5 di*otom\s at ! ends4 ,^! granules are especially cr[d$ ^u cle> yell[ d>t-%ap$ rods1 :i* 9 turn are especially prom95t ^u cry/als & cry/all9e gra9s ( augite t bri/le ) !m1 :ile ! imm$iately surr\nd+ glass has become cle>4 ,!re c be little d\bt t ^! rudim5t>y bodies are /ages 9 ! arre/$ developm5t ( augite cry/als4 ,!re occur also opaque gra9s1 rods & tri*ites1 :i* no d\bt consi/ 9 :ole ( magnetite 7or o!r iron oxide71 or are cru/$ ov] ) t m9]al4 ,at lea/ two broad types ( microscopic /ructure may be recogniz$ among ! basic & int]m$iate dykes4 7#a7 ,holocry/all9e1 or ) only a trifl+ proportion ( int]/itial matt]4 ,?is type includes ! dol]ites & basalts1 z well z rocks :i* ,g]man petrograph]s w\ld class z diabases or diabase-porphyrites4 ,! rocks are v g5]ally *>act]iz$ by ophitic /ructure1 :]e ! la?-%ap$ felsp>s p5etrate ! augite1 & are !re=e ( an e>li] consolidation4 ,9 su* cases !re is a g5]al abs5ce ( any true int]/itial matt]4 ,! rocks ( ?is type are (t5 ri* 9 oliv9e1 & appe> to be on ! :ole consid]ably m basic ?an ^? ( ! second gr\p4 ,x is obs]vable t !y increase 9 numb]s f ! c5tre ( ,scotl& we/w>ds1 & ?r\gh\t ! region ( ! basalt-plateaux !y =m ! prevail+ type4 7#b7 ,9 ?is type !re is a m>k$ proportion ( int]/itial sub/ance1 :i* is ins]t$ 9 w$ge-%ap$ portions among ! cry/allis$ con/itu5ts 7int]s]tal /ructure ( ,ros5bus*74 ,! ophitic /ructure appe>s to be abs5t1 & oliv9e is ei!r extremely r>e or does n occur at all4 ,! rocks ( ?is gr\p are obvi\sly less basic ?an ^? ( ! o!r4 ,!y =m ! l>ge dykes t rise s conspicu\sly ?r\gh ! ,s\? ( ,scotl& & ,nor? ( ,engl&1 & _! g5]al *>act]s are well describ$ by ,mr4 ,teall 9 ! pap] already cit$4 ,9 "s in/ances !y enclose abundant porphyritic felsp>s ( e>li] consolidation1 & !n pres5t mo/ ( ! *>act]s ( &esites4 ,pr(essor ,ros5bus* has ext5d$ ! "n ( ,?oleiites to rocks ( ?is gr\p 9 ! ,nor? ( ,engl&4#aga ,! vitre\s condition is f\nd 9 bo? types1 b is p]haps m frequ5t 9 ! second4 ,! glass ( ! basalts1 h[ev]1 ev5 9 ?9 slices1 is *>act]i/ically opaque f its cr[d$ inclusions2 :ile t ( ! &esitic =ms1 ?\gh black 9 h& specim5s1 appe>s p]fectly transp>5t & sometimes ev5 col\rless 9 ?9 slices4 ,footnote #aga3 ,mikroskopis*e ,physiographie1 #crd edit4 #ajga et seq4 7#c7 ,*emical ,*>act]s4--,! only "o ( ^! to :i* ref]5ce w be made "h is ! v>y+ proportion ( silica4 ,:ile ! dykes z a :ole are ei!r int]m$iate or basic1 "s ( !m conta9 s high a p]c5tage ( silica z to l9k !m ) ! acid rocks4 ,! av]age proportions ( ?is +r$i5t range f less ?an #ej to ne>ly #fj p] c5t4 ,! rocks ) ! l[] p]c5tage ( acid are ri*] 9 ! heavy bases1 & h a specific gravity :i* sometimes rises above #cj4 ,!y include ! true dol]ites & basalts4 ,^?1 on ! o!r h&1 ) ! high] ratio ( silica1 are poor] 9 ! heavy bases1 & h a specific gravity f #bgf to #bif4 ,!y comprise ! ?oleiites1 &esites & o!r m co>sely cry/all9e rocks ( ! great ea/]n & s\?-ea/]n dykes4#agb ,footnote #agb3 ,= analyses ( dykes1 see ,sir ,i4 ,l4 ,bell1 ,proc4 ,roy4 ,soc4 xxiii4 p4 #edf2 ,mr4 ,j4 ,s4 ,grant ,wilson1 ,proc4 ,roy4 ,phys4 ,soc4 ,ed94 v4 p4 #bec2 ,mr4 ,teall1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 p4 #bji2 ,pr(essors ,judd & ,cole1 ,qu>t4 ,j\r4 ,geol4 ,soc4 xxxix4 p4 #ddd4 ,n only d ! dykes diff] consid]ably f ea* o!r 9 _! relative proportions ( silica1 b ev5 ! same dyke may sometimes be f\nd to pres5t a simil> div]sity 9 diff]5t p>ts ( its mass4 ,x has long be5 a famili> fact t ! glassy p>ts ( su* rocks are m acid ?an ! surr\nd+ cry/all9e portions4 ,! orig9al magma may be reg>d$ z a natural glass or fus$ silicate1 9 :i* all ! elem5ts ( ! rock 7 dissolv$1 & :i* necess>ily became m acid z ! v>i\s basic m9]als cry/allis$ out ( x4#agc ,9 ! ,eskdale dyke ! silica p]c5tage ( ?is glassy portion is #ehfg1 t ( ! little k]nels ( black glass disp]s$ ?r\gh ! rock z mu* z #fedi4agd ,9 ! ,dunoon dyke obs]v$ by ,mr4 ,cl\gh ! silice\s f9]-gra9$ ve9s conta9 no less ?an #fhje p] c5t ( silica1 :ile ! mass ( ! dyke itself %[s on analysis only #dgcf p] c5t4#age ,simil> r$ /r+s h be5 notic$ by ! same c>eful obs]v] 9 an ea/ & we/ dyke ne> ,lo*goilhead4 ,f ,mr4 ,teall's exam9ation a l>ge "p ( ! felsp> 9 ^! ve9s is probably or?oclase4 ,x =ms a mu* l>g] p]c5tage ( ! entire rock ?an ! felsp> does 9 normal dol]ites4 ,footnote #agc3 ,on ?is subject see a pap] by ,dr4 ,a4 ,lagorio1 b] die ,natur d] ,glasbasis s[ie d] ,kry/allisationsvorgnge im eruptiv5 ,magma1 ,ts*]mak's ,m9]alog4 ,mit!il4 viii4 7#ahhg71 p4 #dba4 ,footnote #agd3 ,mr4 ,j4 ,s4 ,grant ,wilson1 ,proc4 ,roy4 ,soc4 ,phys4 ,ed94 v4 7#ahhj7 p4 #bec4 ,footnote #age3 ,unpubli%$ analyses made by ! late ,pr(essor ,dittm> ( ,glasg[1 & communicat$ to me by ,mr4 ,cl\gh4 #b4 ,tra*yte ,dykes4--,9 ! ,c[al ,di/rict ( ,argyle%ire1 & 9 ! s\? ( ,skye1 ,mr4 ,cl\gh has enc\nt]$ a limit$ numb] ( dykes ( tra*yte4 ,on a ha/y inspection ^! are n always readily di/+ui%$ f ! basalt-dykes ) :i* !y agree 9 g5]al ext]nal aspect & 9 direction4 ,:]e _! relation to ^! dykes1 h[ev]1 c be det]m9$ !y are f\nd to trav]se !m1 & ?us to be on ! :ole lat]1 ?\gh "o case has be5 obs]v$ :]e a tra*ytic dyke is 9 turn trav]s$ by "o ( ! basic s]ies4 ,mr4 ,cl\gh has suppli$ me ) ! foll[+ notes ( 8 obs]vations reg>d+ ! tra*ytic dykes4 ,!y are all *>act]iz$ by ! possession ( sph]ulitic /ructures ne> _! m>g9s4 ,^! features1 easily p]ceptible to ! nak$ eye1 af=d ! readie/ means ( di/+ui%+ ! dykes ( ?is gr\p4 ,s abundant are ! sph]ulites t !y n infrequ5tly imp+e on ea* o!r 9 long p>allel r[s =m+ rod-l aggregates4 ,?us 9 a dyke ne> ,craig5davie1 at ! head ( ,lo* ,/riv51 num]\s planes ab\t a qu>t] ( an in* ap>t1 & compos$ ( su* close-set rods1 may be obs]v$ runn+ p>allel to ! m>g9al wall = a di/ance ( sev]al in*es f ! edge4 ,mo/ ( ^! planes %[ on _! surfaces t ! rods are always p>allel to ea* o!r1 b may run 9 diff]5t directions 9 ! diff]5t lay]s1 be+ sometimes horizontal1 sometimes v]tical1 or at any angle betwe54 ,on exam9ation1 ea* rod is f\nd to be made up ( polygonal bodies1 ! angles ( :i* are q %>p1 b ) _! sides (t5 slightly curv$1 z if !y _h assum$ _! =ms f ! mutual pressure ( orig9al sph]ical bulbs4 ,fur!r scrut9y %[s t ! polygonal bodies (t5 exhibit an int]nal radiate /ructure4 ,9 ! c5tral p>ts ( ! dyke ! sph]ulitic arrangem5t is n traceable4 ,ab\t a foot f ! m>g9 x beg9s to be recognizable4 ,at a di/ance ( ?ree or f\r in*es ! sph]ulites are ab\t ! size ( peas1 & gradually dim9i% t[>ds ! edge until !y c no long] be se54 ,ano!r *>act]i/ic ( ! tra*yte dykes has be5 f\nd by ,mr4 ,cl\gh to be a useful guide 9 discrim9at+ !m f ! basalt-gr\p4 ,:ile ! amygdales 9 ! latt] are g5]ally rudely sph]ical1 ^? 9 ! tra*ytes are commonly elongat$ 9 ! direction ( ! l5g? ( ! dyke1 & are frequ5tly ?ree qu>t]s ( an in*1 sometimes ev5 an in* & a half1 9 l5g?1 ?\gh less ?an a qu>t] ( an in* 9 bread?4 ,a good example ( ^! tra*ytic dykes1 :i* occurs at ,dunans1 ab\t ! head ( ,gl5d>uel1 has be5 exam9$ microscopically & *emically4 ,! c5tral bett] cry/allis$ portion 0 f\nd by ,mr4 ,teall to be compos$ ma9ly ( small la?-%ap$ cry/als ( or?oclase1 toge!r ) scales ( br[n biotite1 a few prismatic cry/als ( pale some:at alt]$ pyrox5e & scatt]$ granules ( magnetite4 ,! *emical analysis ( ?is rock by ,mr4 ,j4 ,h4 ,play] gave ! foll[+ composition3-- ,silica #efd ,alum9a #aij ,f]ric oxide #ce ,f]r\s oxide #dh ,lime #bf ,magnesia #ae ,soda #de ,pota% #ej ,loss on ignition #bf ---- #iii #d4 ,,hade ,9 ! majority ( cases1 especially among ! great s+le dykes1 ! intrusive rock has assum$ a position ne>ly or q v]tical4 ,b occasionally1 :]e "o ( ^! solit>y examples crosses a deep valley1 a slight hade is p]ceptible by ! deviation ( ! l9e ( ! dyke f its normal c\rse4 ,s$gwick long ago notic$ t ! ,clevel& dyke has1 9 places1 an incl9ation ( at lea/ #hj to its ,n4,e4 side4#agf ,9 ! coal-work+s1 also1 a trifl+ deviation f ! v]tical is sometimes p]ceptible1 especially :]e a dyke has f\nd its way along a previ\sly exi/+ l9e ( fault1 z 9 sev]al examples 9 ,/irl+%ire4 ,b 9 ^? di/ricts :]e ! dykes are greg>i\s1 dep>tures f ! v]tical position are n infrequ5t1 m p>ticul>ly ne> ! great basalt-plateaux4 ,x 0 notic$ by ,neck]1 t ev5 9 su* a dyke-fill$ region z ,arran1 almo/ all ( ! dykes are v]tical1 ?\gh sometimes deviat+ f t position to ! ext5t ( #bj4agg ,b]g] f\nd t ! angle ( deviation among ^? ( ! nor? ( ,irel& ranges f #i to #bj1 ) a mean ( #ac4agh ,! mo/ oblique examples are probably ^? :i* occur 9 ! basalt-plateaux ( ! ,inn] ,hebrides1 :]e ! same dyke 9 "s p>ts ( its c\rse runs horizontally betwe5 two b$s1 across :i* x also desc5ds v]tically 7see ,figs4 #bea1 #beb1 #cgd74 ,b ) ^! m9or exceptions1 ! v]ticality ( ! great sy/em ( dykes1 po9t+ to ! p]p5dicul> fissure-walls betwe5 :i* ! molt5 rock asc5d$1 is "o ( ! mo/ notable features 9 _! geological /ructure4 ,9 ! ,/ra? di/rict ( ,skye ,mr4 ,h>k] has notic$ t :ile ! e>li] dykes h sometimes a hade ( #de1 ^? y\ng] ?an ! granophyre are g5]ally v]tical or ne>ly s4 ,9 ! ,bla? ,bhe9n gr\p ( hills1 h[ev]1 z already allud$ to1 he has obs]v$ t x is ! y\nge/ dykes :i* are incl9$ 9 a nor?-we/]ly direction1 ) a hade ( z mu* z #dj f ! horizon4 ,footnote #agf3 ,cambridge ,phil4 ,trans4 ii4 p4 #bh4 ,footnote #agg3 ,trans4 ,roy4 ,soc4 ,ed94 xiv4 p4 #fgg4 ,footnote #agh3 ,trans4 ,geol4 ,soc4 iii4 p4 #bbg4 #e4 ,,bread? ,an obvi\s *>act]i/ic ( mo/ dykes is ! app>5t uni=mity ( _! bread?4 ,_m ( !m1 z expos$ along %ore-sections1 v>y z little 9 dim5sions z well-built walls ( masonry d4 ,dep>tures f su* uni=mity may (t5 inde$ be not$1 :e!r a dyke is foll[$ lat]ally or v]tically4 ,! l>ge/ am\nt ( v>iation is1 ( c\rse1 to be f\nd among ! dykes ( ! greg>i\s type1 ! ?9n] examples ( :i* may dim9i% to a wid? ( only "o in* or less1 :ile _! av]age bread? is mu* small] ?an 9 ! case ( ! great solit>y dykes4 ,9 ! di/rict ( ,/ra?aird1 9 ,skye1 ,maccullo* e/imat$ t ! rem>kably abundant dykes !re develop$ v>y f #e to #bj feet 9 bread?1 b ) an av]age bread? ( n m ?an #aj feet4#agi ,9 ! isle ( ,arran1 accord+ to ,neck]'s c>eful measurem5ts1 mo/ ( ! dykes range f #b or #c to #aj or #ae feet1 b "s dim9i% to a few in*es1 :ile o!rs rea* a wid? ( #bj1 #cj1 or ev5 #ej feet4#ahj ,9 ! ,nor? ( ,irel&1 ,b]g] obs]v$ t ! av]age bread? ( ?irty-eight dykes trav]s+ primitive rocks 7s*i/1 granites1 etc47 0 #i feet2 & ( tw5ty-f\r 9 ,second>y rocks1 #bd feet4#aha ,footnote #agi3 ,trans4 ,geol4 ,soc4 iii4 p4 #hj4 ,footnote #ahj3 ,trans4 ,roy4 ,soc4 ,ed94 xiv4 p4 #fij et seq4 ,footnote #aha3 ,trans4 ,geol4 ,soc4 iii4 p4 #bbf4 ,he believ$ t dykes 9 ,second>y rocks rea* a mu* great] ?ickness ?an 9 o!r =mations4 ,my own obs]vations d n confirm ?is g5]alisation4 ,b :5 we pass to ! great solit>y dykes1 t run s f> & s cont9u\sly across ! c\ntry1 we enc\nt] mu* ?ick] masses ( igne\s rock4 ,mo/ ( ! measurem5ts ( ^! dykes h be5 made at ! surface1 & ! v>iations not$ 9 _! bread? occur along _! horizontal ext5sion4 ,! ,clevel& dyke1 :i* is ! longe/ 9 ,brita91 v>ies f #ae feet to m ?an #ajj feet1 ) p]haps an av]age wid? ( betwe5 #gj & #ij feet4#ahb ,"s ( ! great dykes t cross ,scotl& are ( l>g] dim5sions4 ,mo/ ( !m1 h[ev]1 l t ( ,clevel&1 are liable to consid]able v>iations 9 bread? :5 foll[$ along _! l5g?4 ,! dyke :i* runs f ! ea/]n coa/ across ! ,*eviot ,hills & ,teviotdale to ! head ( ! ,ale ,wat]1 is 9 "s places only #aj feet broad1 b at its wide/ p>ts is probably ab\t #ajj feet4 ,! ,eskdale & ,m(fat dyke is 9 p>ts ( its c\rse #ahj feet wide1 b else:]e x dim9i%es to n m ?an #dj feet4 ,^! v>iations are repeat$ at irregul> int]vals1 s t ! dyke alt]nately wid5s & contracts z its c\rse is trac$ across ! hills4 ,"s ( ! dykes fur!r to ! nor? & we/ atta9 yet m gigantic proportions4 ,t :i* crosses ,cantyre opposite ,ardlamont ,po9t has be5 measur$ by ,mr4 ,j4 ,b4 ,hill1 ( ! ,geological ,survey1 :o f9ds x to be f #aej to #ahj feet broad on ! %ore ( ,lo* ,fyne1 & to swell out beyond ! we/ side ( ,lo* ,t>b]t to a bread? ( #bdj to #bgj feet4 ,a dyke ne> ,/ra?miglo1 9 ,fife1 is ab\t #djj feet wide4 ,! broade/ dyke kn[n to me is "o :i* ,i trac$ ne> ,bei?1 9 ,ayr%ire1 trav]s+ ! ,c>bonif]\s ,lime/one4 ,its maximum wid? is #fdj feet4 ,footnote #ahb3 ,at ,cockfield1 :]e x has long be5 qu>ri$1 x v>ies f #ae to #ff feet2 at ,arma?watie1 9 ! vale ( ! ,ed51 x is ab\t #ed feet 7,mr4 ,teall1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 p4 #baa74 ,un=tunately1 x is mu* less easy to get evid5ce ( ! wid? ( dykes at diff]5t levels 9 _! v]tical ext5sion4 ,yet ?is is obvi\sly an important po9t 9 ! !oretical discussion ( _! orig94 ,two means are available ( obta9+ in=mation on ! subject--7a7 f m9+ op]ations1 & 7b7 f obs]vations at precipices & betwe5 hill-cre/s & valley-bottoms4 7a7 ,9 ! ,c5tral ,scotti% coal-field & 9 t ( ,ayr%ire1 "s l>ge dykes h be5 cut ?r\gh at dep?s ( two or ?ree hundr$ feet b5ea? ! surface4 ,b !re does n appe> to be any well-asc]ta9$ v>iation betwe5 _! wid? s f> bel[ gr\nd & at ! surface4 ,9 n a few cases1 inde$1 dykes are met ) 9 ! l[] work+s ( ! coal-pits :i* d n rea* ! surface or ev5 ! work+s 9 ! high] coals4 ,su* upw>d t]m9ations ( dykes w be aft]w>ds consid]$1 & x w be %[n t t[>ds its upp] limit a dyke may rapidly dim9i% 9 wid?4 7b7 ,m def9ite in=mation1 & (t5 f a wid] v]tical range1 is to be ga!r$ on coa/-cliffs & 9 hilly di/ricts1 :]e ! same dyke c be foll[$ ?r\gh a v]tical range ( _m hundr$ feet4 ,b s f> z my own obs]vations g1 no g5]al rule c be e/abli%$ t dykes s5sibly v>y 9 wid? z !y are trac$ upw>d4 ,e "o :o has visit$ ! basalt-precipices ( ,antrim or ! ,inn] ,hebrides1 :]e dykes are s num]\s1 w rememb] h[ uni=m is _! bread? z !y run l ribbons up ! faces ( ! esc>pm5ts4#ahc ,n[ & !n "o ( !m may be obs]v$ to die out1 b 9 su* cases 7:i* are f> f common7 ! normal wid? is usually ma9ta9$ up to )9 a few feet ( ! t]m9ation4 ,footnote #ahc3 ,?is po9t did n escape ! att5tion ( t excell5t obs]v]1 ,b]g]1 9 8 exam9ation ( ! dykes 9 ! ,nor? ( ,irel&4 ,we f9d him express+ himself ?us3--,! dep? to :i* ! dykes desc5d is unkn[n2 & aft] hav+ obs]v$ ! sections ( a great _m along ! coa/ 9 cliffs f #ej to #djj feet 9 height1 ,i h n be5 able to asc]ta9 7except 9 "o or two cases7 t _! sides conv]ge or h a w$ge=m t5d5cy 7,trans4 ,geol4 ,soc4 iii4 p4 #bbg74 ,all ov] ! s\!rn half ( ,scotl&1 :]e ! dykes run along ! cre/s ( ! hills & also cross ! valleys1 a diff]5ce ( level am\nt+ to sev]al hundr$ feet may (t5 be obta9$ betwe5 adjac5t p>ts ( ! same dyke4 ,b ! bread? ( igne\s rock is n p]ceptibly great] 9 ! valleys ?an on ! ridges4 ,! dep? ( b\ld] clay & o!r sup]ficial deposits on ! valley bottoms1 h[ev]1 too frequ5tly conceals ! dykes at _! l[e/ levels4 ,p]haps ! be/ sections 9 ! c\ntry = ! /udy ( ?is int]e/+ "p ( dyke-/ructure are to be f\nd among ! high] hills ( ! ,inn] ,hebrides1 su* z ! qu>tzites ( ,jura & ! granophyres & gabbros ( ,skye4 ,on ^! b>e rocky declivities1 num]\s dykes may be foll[$ f almo/ ! sea-level up to ! rugg$ & spl9t]$ cre/s1 a v]tical di/ance ( betwe5 #bjjj & #cjjj feet4 ,! dykes are c]ta9ly n z a rule s5sibly less 9 wid? on ! hill-tops ?an 9 ! gl5s4 ,s f>1 !re=e1 z ,i h be5 able to ga!r ! evid5ce1 !re does n appe> to me to be1 z a g5]al rule1 any appreciable v>iation 9 ! wid? ( dykes = at lea/ #bjjj or #cjjj feet ( _! desc5t4 ,! fissures :i* !y fill$ mu/ obvi\sly h _h ne>ly p>allel walls = a long way d[n4 #f4 ,,int]ruptions ,,( ,,lat]al ,,cont9uity ,9 trac+ ! great solit>y dykes across ! c\ntry1 ! geologi/ is (t5 surpris$ to meet ) gaps1 v>y+ 9 ext5t f a few hundr$ feet to sev]al miles1 9 :i* no trace :atev] ( ! igne\s rock c be detect$ at ! surface4 ,?is disappe>ance is n always explicable by ! dep? ( ! cov] ( sup]ficial accumulations2 = x may be obs]v$ ov] gr\nd :]e ! nak$ rocks come almo/ ev]y:]e to ! surface1 & :]e1 !re=e1 if ! conspicu\s mat]ial ( ! dykes exi/$1 x c\ld n fail to be f\nd4 ,no dyke supplies bett] illu/rations ( ?is discont9uity ?an t ( ,clevel&4 ,trac$ nor?-we/w>d across ! ,c>bonif]\s tracts t lie betwe5 ! m\? ( ! ,tees & ! ,yale ( ! ,ed51 ?is dyke disappe>s sometimes = a di/ance ( six or eight miles4 ,9 ! m9+ gr\nd r\nd ! head ( ! ,s\? ,tyne ! rocks are b>e1 s t ! abs5ce ( ! dyke among !m c only be acc\nt$ = by its n rea*+ ! surface4 ,yet !re c be no d\bt t ! v>i\s sep>at$ exposures1 :i* h ! same di/9ctive li?ological *>act]s & occur on ! same p]si/5t l9e1 are all portions ( "o dyke :i* is cont9u\s at "s dep? bel[ gr\nd4 ,we h ?us an indication ( ! exce$+ly irregul> upw>d limit ( ! dykes1 z w be m p>ticul>ly discuss$ fur!r on4 ,b !re are also in/ances :]e ! cont9uity is int]rupt$ & !n resum$ on a diff]5t l9e4 ,"o ( ! be/ illu/rations ( ?is "* is suppli$ by ! l>ge dyke :i* rises ?r\gh ! hills ab\t a mile s\? ( ,l9li?g[ & runs we/w>d across ! coal-field4 ,at ,blackbraes x ends (f 9 a po9t1 & is n f\nd aga9 to ! we/w>d 9 any ( ! coal-work+s4 ,b little m ?an a qu>t] ( a mile to ! s\? a precisely simil> dyke beg9s1 & /rikes we/w>d p>allel to ! l9e ( ! fir/ "o4 ,! two sep>at$ /rips ( igne\s rock ov]lap ea* o!r = ab\t ?ree-qu>t]s ( a mile4 ,b t !y are m]ely int]rupt$ portions ( :at is really a s+le dyke c h>dly be que/ion$4 ,a second example is furni%$ by ano!r ( ! great dykes ( ! same di/rict1 :i* aft] runn+ = ab\t twelve miles 9 a ne>ly ea/ & we/ direction sudd5ly /ops at ,*ry/on1 & beg9s aga9 9 ! same direction1 b on a l9e ab\t a ?ird ( a mile fur!r nor?4 ,su* examples s]ve to m>k out irregul>ities 9 ! great fissures up :i* ! mat]ials ( ! dykes rose4 #g4 ,,l5g? ,9 ^? di/ricts :]e ! small & cr[d$ dykes ( ! greg>i\s type are develop$1 "o _c usually trace !m = m ?an a %ort di/ance4 ,! longe/ examples kn[n to me are ^? :i* h be5 mapp$ ) mu* pati5ce & skill by ,mr4 ,cl\gh 9 ,ea/]n ,argyle%ire4 ,"s ( !m he has be5 able to track ov] hill & valley = f\r or five miles1 ?\gh ! great majority are mu* %ort]4 ,9 ,arran & 9 ! ,inn] ,hebrides1 x is seldom possible to foll[ :at we c be sure is ! same dyke = m ?an a few hundr$ y>ds4 ,?is difficulty arises p>tly1 no d\bt1 f ! frequ5t spread ( peat or o!r sup]ficial accumulation :i* conceals ! rocks1 & p>tly also f ! great numb] ( dykes & ! want ( suffici5tly di/9ct li?ological *>act]s = ! id5tification ( any p>ticul> "o4 ,b mak+ e all[ance = ^! ob/acles1 we are compell$1 ,i ?9k1 to reg>d ! greg>i\s dykes z ess5tially %ort z well z relatively irregul>4 ,9 /rik+ contra/ to ^!1 come ! great solit>y dykes4 ,9 e/imat+ _! l5g?1 z ,i h already rem>k$1 we mu/ be> 9 m9d ! fact t !y occasionally und]go int]ruptions ( cont9uity ow+ to ! local failure ( ! igne\s mat]ial to rise to ! level ( :at is n[ ! surface ( ! gr\nd4 ,a n>r[ wall-l mass ( &esite or dol]ite1 :i* s9ks b5ea? ! surface = a few hundr$ y>ds1 or = sev]al miles1 & reappe>s on ! same l9e ) ! same petrographical *>act]s1 :ile !re may be no simil> rock = miles to "r & left1 c only be "o dyke prolong$ und]nea? 9 ! same great l9e ( fissure4 ,b ev5 if we re/rict our measurem5ts ( l5g? to ^? dykes or p>ts ( dykes :]e no s]i\s int]ruption ( cont9uity takes place1 we _c fail to be a/oni%$ at ! p]si/5ce ( ^! /rips ( igne\s rock ?r\gh ! mo/ div]se k9ds ( geological /ructure4 ,a few illu/rative examples ( ?is feature may be select$4 ,x w be obs]v$ t ! longe/ & broade/ dykes are f\nd fur!/ f ! basalt-plateaux1 :ile ! %orte/ & n>r[e/ are mo/ abundant ne> ^! plateaux4 ,n f> f :at ,i h tak5 provisionally z ! nor!rn b\nd>y ( ! dyke region1 two dykes occur :i* h be5 mapp$ f ! head ( ,lo* ,goil by ,arro*> across ,lo*s ,lomond & ,katr9e by ,b5 ,l$i to ,gl5 ,artney1 :5ce !y /rike into ! ,old ,r$ ,s&/one ( ,/ra?more1 & run on to ! ,tay ne> ,p]?--a total di/ance ( ab\t #fj miles4 ,if ! dyke :i* cont9ues 9 ! same l9e on ! o!r side ( ! e/u>y ( ! ,tay beyond ,newburgh1 is a prolongation ( "o ( ^!1 !n its entire l5g? exce$s #gj miles4 ,a few miles fur!r s\?1 "o ( a gr\p ( dykes c be foll[$ f ! he>t ( ,dumb>ton%ire by ,call&] across ! ,braes ( ,d\ne to ,au*t]>d]--a di/ance ( #dg miles1 ) an av]age bread? ( m ?an #ajj feet4 ,9 ! di/rict betwe5 ! ,=? & ,clyde a numb] ( long p>allel dykes c be trac$ = _m miles across hill & pla91 & ?r\gh ! coal-fields4 ,"o ( ^! is cont9u\s = #be miles f ! he>t ( ,l9li?g[%ire into ,lan>k%ire4 ,/ill long] is ! dyke :i* runs f ! ,fir? ( ,=? at ,grangem\? we/w>d to ! ,clyde1 opposite ,gre5ock--a di/ance ( ab\t #cf miles4 ,com+ s\?w>d1 we enc\nt] a /rik+ s]ies ( s+le dykes on ! upl&s betwe5 ! c\nties ( ,lan>k & ,ayr1 :5ce !y /rike into ! ,silurian hills ( ! s\!rn c\nties4 ,"o ( ^! runs across ! cre/ ( ! ,haugh%aw ,hills1 & c be foll[$ = "s #cj miles4 ,b if1 z is probable1 x is prolong$ 9 "o ( ! dykes t trav]se ! moorl&s ( ! nor? ( ,ayr%ire & s\? ( ,r5frew%ire to ! ,clyde1 its actual l5g? mu/ be at lea/ twice t di/ance4 ,! great ,m(fat & ,eskdale dyke /rikes = m ?an #ej miles across ! ,s\? ( ,scotl& & ,nor? ( ,engl&4 ,! ,hawick & ,*eviot dyke runs = #bf miles 9 ,scotl& & = #cb miles 9 ,nor?umb]l&4 ,b ! mo/ rem>kable in/ance ( p]si/5ce is furni%$ by ! ,clevel& dyke4 ,f :]e x is fir/ se5 ne> ! coa/-cliffs ( ,york%ire ! /rip ( igne\s rock c be foll[$1 ) frequ5t int]ruptions1 dur+ :i* = sometimes sev]al miles no trace ( x appe>s at ! surface1 across ! ,nor? ( ,engl& z f> z ,dal/on ,hall s\? ( ,c>lisle1 beyond :i* ! gr\nd onw>ds to ! ,solway ,fir? is deeply cov]$ ) sup]ficial deposits4 ,! total di/ance ?r\gh :i* ?is dyke c be recogniz$ is ?us ab\t #aaj miles4 ,b x probably goes fur!r /ill4 ,on ! opposite side ( ! ,solway1 a dyke :i* runs 9 ! same l9e1 rises ?r\gh ! ,p]mian /rata a little to ! ea/ ( ! m\? ( ! ,ni?4 ,"s miles fur!r to ! nor?-we/1 ne> ,moniaive1 ,mr4 ,j4 ,horne1 9 ! progress ( ! ,geological ,survey1 trac$ a d>k compact dyke ) k]nels ( basalt-glass ne> its m>g91 runn+ 9 ! same nor?-we/]ly direction4 ,/ill fur!r on 9 ! same l9e1 ano!r simil> rock is f\nd high on ! flanks ( ! l(ty hill kn[n z ,w9dy ,/&>d4 ,& la/ly1 9 ! ,ayr%ire coal-field1 a dyke /ill cont9u+ ! same tr5d1 runs = sev]al miles1 & /rikes out to sea ne> ,pre/wick4 ,x _c1 ( c\rse1 be prov$ t ^! deta*$ ,scotti% protrusions belong to "o great dyke1 or t if su* a cont9u\s dyke exi/s1 x is a prolongation ( t f ,clevel&4 ,at ! same "t1 ,i am on ! :ole incl9$ to connect ! v>i\s outcrops toge!r z ^? ( "o prolong$ subt]ranean wall ( igne\s rock4 ,! di/ance f ! la/ visible portion ( ! ,clevel& dyke ne> ,c>lisle to ! dyke t runs out into ! ,fir? ( ,clyde ne> ,pre/wick1 is ab\t #hj miles4 ,if we consid] ?is ext5sion z a "p ( ! great ,nor? ( ,engl& dyke1 !n ! total l5g? ( ?is rem>kable geological feature w be ab\t #aij miles4 #h4 ,,p]si/5ce ,,( ,,m9]al ,,*>act]s ,n less rem>kable ?an _! l5g? is ! pres]vation ( _! normal petrographical *>act]s by "s dykes = long di/ances4 ,9 ?is respect ! ,clevel& dyke may aga9 be cit$ z a typical example4 ,! megascopic & microscopic /ructures ( ! rock ( ?is dyke di/+ui% x among ! o!r eruptive rocks ( ! ,nor? ( ,engl&4 ,& ^! peculi>ities x ma9ta9s ?r\gh\t its c\rse4#ahd ,simil> ?\gh less prom95t uni=mity may be trac$ among ! long solit>y dykes ( ! ,s\? ( ,scotl&1 ! *ief v>iations 9 ^! aris+ f ! great] or less ext5t to :i* ! orig9al glassy magma has be5 reta9$4 ,! same dyke w at "o "p ( its c\rse %[ abundant glassy matt] ev5 to ! nak$ eye1 :ile at a %ort di/ance ! vitre\s gr\ndmass has be5 devitrifi$1 & its =m] pres5ce c only be detect$ ) ! aid ( ! microscope4 ,:]e a dyke has caught up & absorb$ abundant =eign mat]ials its composition naturally v>ies consid]ably f po9t to po9t4 ,mr4 ,h>k] has obs]v$ "s good examples ( ?is v>iation 9 ,skye4 ,footnote #ahd3 ,see ! c>eful exam9ation ( ?is dyke by ,mr4 ,teall1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xl4 p4 #bji4 ,,*apt] ,,xxxv ,,! ,,sy/em ,,( ,,dykes--cont9u$ ,direction--,t]m9ation upw>d--,kn[n v]tical ,ext5sion--,evid5ce z to ! movem5t ( ! ,molt5 ,rock 9 ! ,fissures--,bran*es & ,ve9s--,connection ( ,dykes ) ,intrusive ,%eets--,int]section ( ,dykes--,dykes ( m ?an "o infill+--,contact ,metamorphism ( ! ,dykes--,relation ( ! ,dykes to ! ,geological ,/ructure ( ! ,di/ricts :i* !y trav]se--,data = e/imat+ ! ,geological ,age ( ! ,dykes--,orig9 & ,hi/ory ( ! ,dykes4 #i4 ,,direction ,ano!r *>act]i/ic feature ( ! dykes is _! g5]ally rectil9e> c\rse4 ,s true are ! solit>y dykes to _! normal tr5d t1 9 spite ( v>y+ inequalities ( surface & wide div]sities ( geological /ructure 9 ! di/ricts :i* !y trav]se1 !y run ov] hill & dale almo/ ) ! /raightness ( l9es ( ,roman road4 ,9 ! di/ricts :]e ! greg>i\s type prevails1 ! dykes dep>t mo/ widely f ! "* ( ! great solit>y s]ies1 b /ill t5d to run 9 /raight or approximately /raight l9es1 or1 if wavy 9 _! c\rse1 to pres]ve a g5]al p>allelism ( direction4 ,yet ev5 among ! great p]si/5t dykes in/ances may be cit$ :]e ! rectil9e> tr5d is ex*ang$ = a succession ( zig-zags1 ?\gh ! normal direction is on ! :ole ma9ta9$4 ,9 su* cases1 x is evid5t t ! fissures 7 n long /raight dislocations1 l ! l>g] l9es ( fault 9 ! e>?'s cru/1 b 7 r not*$ r5ts or cracks :i*1 ?\gh keep+1 on ! :ole1 "o dom9ant direction1 7 cont9ually be+ deflect$ = %ort di/ances to ei!r side4 ,z a good illu/ration ( ?is "*1 ref]5ce may be made to ! ,*eviot & ,hawick dyke4 ,9 ,teviotdale1 ?is dyke c be foll[$ cont9u\sly among ! rocky knolls1 s t its deviations c be se5 & mapp$4 ,f ! m$ian l9e ( av]age tr5d ! sali5t angles sometimes retire fully a qu>t] ( a mile on ei!r side4 ,"s examples ( ! same feature may be notic$ 9 ! ,eskdale dyke4 ,! l>ge dyke :i* runs we/w>d f ,dunoon has be5 obs]v$ by ,mr4 ,cl\gh to *ange %>ply 9 direction ?ree times 9 f\r miles1 runn+ occasionally = a %ort di/ance at a "r angle to its g5]al direction 7see ,fig4 #beg74 ,among ^! solit>y dykes also1 ?\gh ! p]si/5ce ( _! tr5d is s pr$om9ant1 !re occur in/ances :]e ! g5]al direction und]goes great *ange4 ,"s ( ! mo/ rem>kable cases ( ?is k9d h be5 mapp$ by ,mr4 ,b4 ,n4 ,pea* & ,mr4 ,r4 ,l4 ,jack1 9 ! c\rse ( ! ,geological ,survey ( ,p]?%ire4 ,sev]al important dykes /rike across ! ,old ,r$ ,s&/one pla9 = _m miles 9 a direction slightly s\? ( we/4 ,b :5 !y approa* ! rocks ( ! ,highl& bord] 9 ,gl5 ,artney1 !y b5d r\nd to s\?-we/1 & cont9ue _! c\rse along t new l9e4 ,_m ye>s ago ,i call$ att5tion to ! dom9ant tr5d ( ! dykes f nor?-we/ to s\?-ea/4#ahe ,subsequ5t rese>* has %[n ?is to be on ! :ole ! preval5t direction ?r\gh\t ! :ole region ( dykes4 ,b ! detail$ mapp+1 c>ri$ on by my colleagues & myself 9 ! ,geological ,survey1 has br\ght to light "s curi\s & int]e/+ v>iations f ! normal tr5d4 ,9 ! di/ricts :]e dykes ( ! greg>i\s type ab\nd !re is sometimes no "o preval5t direction1 b ! dykes /rike to almo/ all po9ts ( ! compass4 ,( ! ,arran dykes1 s c>efully catalogu$ by ,neck]1 only ab\t a ?ird h a g5]al nor?-we/]ly c\rse4 ,b 9 ,ea/]n ,argyle%ire ! abundant dykes mapp$ by ,mr4 ,cl\gh tr5d almo/ )\t exception t[>ds ,n4,n4,w4 ,9 ! ,nor? ( ,irel&1 ,b]g] f\nd ! direction ( ?irty-"o dykes to v>y f #ag to #ga ,w4 ( ,n41 giv+ a mean ( ,n4 #cf ,w4#ahf ,9 ,islay1 ,jura1 ,eigg1 ,mull1 & ,skye ! mean ( sev]al hundr$ obs]vations has giv5 me simil> results4 ,among ! ,inn] ,hebrides1 h[ev]1 ?\gh ! g5]al nor?-we/]ly tr5d is *>act]i/ic1 _m ( ! lat] dykes %[ m>k$ dep>tures f x4 ,?us 9 ,/ra?1 ,skye1 "s ( ! y\nge/ foll[ a ne>ly nor? & s\? direction 7,fig4 #bec74 ,9 ! ,bla? ,bhe9 hill-range1 ,mr4 ,h>k] has f\nd t ! late/ dykes cut ! gabbro at "r angles to ! preval5t tr5d & are fur!r di/+ui%$ by _! l[ hade4 ,footnote #ahe3 ,trans4 ,roy4 ,soc4 ,ed94 xxii4 7#ahfa71 p4 #fej4 ,footnote #ahf3 ,trans4 ,geol4 ,soc4 iii4 p4 #bbe4 ,x appe>s1 !re=e1 t ?\gh !re is sometimes extraord9>y local div]sity 9 ! direction ( ! dykes 9 ^? di/ricts :]e !y pres5t ! greg>i\s type1 ! g5]al nor?-we/]ly tr5d c usually /ill be recogniz$4 ,b :5 we turn to ! long massive solit>y dykes1 we soon p]ceive a rem>kable *ange 9 _! direction z we foll[ !m nor?w>d into ,scotl&4 ,i =m]ly po9t$ out h[ ! g5]al nor?-we/]ly tr5d becomes ea/ & we/ 9 ! ,lo?ians1 ) a t5d5cy to ve] a little to ! s\? ( we/ & nor? ( ea/4#ahg ,?is dep>ture f ! normal direction is n[ se5 to be "p ( a rem>kable radial arrangem5t ( ! dykes4 ,beg9n+ at ! s\!rn m>g9 ( ! dyke-region1 we h ! notable example ( ! ,clevel& dyke1 :i* 9 its c\rse f ,clevel& to ,c>lisle runs ne>ly ,w4 #ae ,n4 ,! ,eskdale dyke has an av]age tr5d ( ,w4 #cb ,n41 & ! same g5]al direction is ma9ta9$ by ! gr\p ( dykes :i* run f ! ,s\!rn ,upl&s across ! s\?-we/ ( ,lan>k%ire & nor?-ea/ ( ,ayr%ire4 ,b proce$+ nor?w>ds we obs]ve ! tr5d to turn gradually r\nd t[>ds ! we/4 ,! dyke t runs f ne> ! m\? ( ! ,coquet across ! ,*eviot ,hills to beyond ,hawick has a g5]al c\rse ( ,w4 #h ,n4 ,9 ! great c5tral coal-field ( ,scotl& ! av]age direction may be tak5 to be ne>ly ea/ & we/1 ! same dyke runn+ sometimes to ! nor?1 & sometimes to ! s\? ( t l9e4 ,b imm$iately to ! nor? a decid$ t5d5cy to ve] r\nd s\?w>ds makes its appe>ance4 ,?us ! long dyke :i* runs f ! ,c>se ( ,/irl+ ?r\gh ! ,campsie ,fells to ! ,clyde we/ ( ,lev51 has a mean direction ( ,w4 #e ,s4 ,?is cont9ues to be ! preval5t tr5d ( ! rem>kable s]ies ( dykes :i* crosses ! ,old ,r$ ,s&/one pla9s1 ?\gh "s ( ^! rev]t 9 :ole or 9 "p to ! m usual direction by keep+ a little to ! nor? ( we/4 ,ev5 z f> z ,lo* ,tay & ! head ( ,/ra?>dle1 ! c\rse ( ! dykes cont9ues to be to ! s\? ( we/4 ,trac+ ^! l9es ^u a map ( ! c\ntry we p]ceive t !y radiate f an area ly+ along ! ea/]n "p ( ,argyle%ire & ! head ( ! ,fir? ( ,clyde 7see ,map ,i474 ,footnote #ahg3 ,trans4 ,roy4 ,soc4 ,ed94 xxii4 p4 #fea4 ,illu/ration3 ,fig4 #bda4--,section along ! l9e ( ! ,clevel& ,dyke at ,cliff ,ridge1 ,guisbr\gh 7,g4 ,b>r[74 ,scale1 #ab in*es to #a mile4 #aj4 ,,t]m9ation ,,upw>ds ,x 0 po9t$ out _m ye>s ago by ,w9* t "s ( ! dykes :i* trav]se ! ,nor?umb]l& coal-field d n cut ! ov]ly+ ,magnesian ,lime/one4 ,! ,hett dyke1 s\? ( ,durham1 is said to end (f abruptly aga9/ ! floor ( ! lime/one4#ahh ,"h & !re1 among ! precipices ( ! ,inn] ,hebrides1 a dyke may be se5 to die out be=e x rea*es ! top ( ! cliff4 ,b 9 ! va/ majority ( cases1 no evid5ce rema9s z to h[ ! dykes t]m9at$ upw>ds4 ,i h ref]r$ to ! occasional int]ruptions ( ! cont9uity ( a dyke1 :]e1 ?\gh ! rock does n rea* ! surface1 x mu/ be pres5t 9 ! fissure und]nea?4 ,su* int]ruptions %[ t1 9 "s places at lea/1 !re 0 no rise ( ! rock ev5 up to ! level ( :at is n[ ! surface ( ! gr\nd1 & t ! upw>d limit ( ! dykes mu/ h be5 exce$+ly irregul>4 ,footnote #ahh3 ,?is is express$ 9 ! ,geological ,survey ,map1 ,%eet #ic1 ,n4,e4 ,excell5t illu/rations ( ?is feature are suppli$ by sections on ! l9e ( ! ,clevel& dyke4 ,t[>ds its s\?-ea/]ly extremity1 ?is great b& ( igne\s rock asc5ds f ! l[ ,triassic pla9 ( ! ,tees into ! high upl&s ( ,clevel&4 ,its c\rse across ! ridges & valleys !re has be5 c>efully trac$ = ! ,geological ,survey by ,mr4 ,g4 ,b>r[1 :o has %[n t ov] c]ta9 p>ts ( its c\rse x does n rea* ! surface1 b rema9s conceal$ "u ! ,jurassic rocks1 :i* x nev] succe$$ 9 p5etrat+4 ,b t 9 places x comes )9 a few feet ( ! soil is %[n by ! bak$ %ale at ! surface1 = ! alt]ation :i* x has induc$ on ! surr\nd+ rocks only ext5ds a few feet f its m>g94 ,^! int]ruptions ( cont9uity %[ h[ unev5 is ! upp] limit ( ! dyke4 ,! *>act]i/ic porphyritic rock may be obs]v$ runn+ up "o side ( a hill to ! cre/1 b nev] rea*+ ! surface on ! o!r side4 ,at ,cliff ,ridge1 = example1 ab\t ?ree miles s\?-we/ ( ,guisbr\gh1 ,mr4 ,b>r[ has foll[$ x up to ! summit on ! we/ side2 b has f\nd t on ! ea/ side x does n pi]ce ! %ales1 :i* !re =m ! declivity4 ,?is /ructure is repres5t$ 9 ,fig #bda4 ,! v]tical di/ance betwe5 ! summit to ! left1 :]e ! dyke 7b7 disappe>s1 & ! po9t to ! "r1 :]e ! ,lias %ale 7a7 ( ! hillside is conceal$ by drift 7c71 am\nts to #bej feet1 ! horizontal di/ance be+ a little m ?an #ijj feet4 ,b z ! %ale :5 la/ se5 at ! foot ( ! slope is q unalt]$1 ! dyke mu/ !re be /ill "s little di/ance b5ea? ! surface1 s t ! v]tical ext5sion ( ?is upw>d tongue ( ! dyke mu/ be m ?an #bej feet4 ,mr4 ,b>r[1 to :om ,i am indebt$ = ^! p>ticul>s1 has also drawn ! accompany+ section 7,fig4 #bdb7 along ! c\rse ( ! dyke = a di/ance ( ne>ly #aa miles ea/w>d f ! locality repres5t$ 9 ,fig4 #bda4 ,f ?is section x w be obs]v$ t 9 t space !re are at lea/ ?ree tongues or upw>d projections ( ! upp] limit ( ! dyke4 ,sev]al additional examples ( ! same /ructure are to be se5 fur!r ea/ t[>ds ! la/ visible outcrop ( ! dyke4 ,illu/ration3 ,fig4 #bdb4--,section along ! c\rse ( ! ,clevel& ,dyke1 at ! head ( ,lonsdale1 ,york%ire 7,g4 ,b>r[1 9 ! ,memoirs ( ! ,geol4 ,surrey1 ,geology ( ,clevel&1 p4 #fa74 a1 ,liassic %ales1 s&/ones & iron/ones2 b1 ! dyke4 ,ano!r feature connect$ ) ! upw>d t]m9ation ( ! dyke is well se5 9 "s p>ts ( ! gr\nd ?r\gh :i* ! two =ego+ sections are tak54 ,mr4 ,b>r[ in=ms me t at ,ayton a level c\rse has be5 driv5 into ! hill = m9+ op]ations1 at a height ( #djj feet above sea-level1 & ! dyke has !re be5 asc]ta9$ to be #hj feet broad4 ,high] on ! hill1 close to ! #gej feet cont\r--l9e1 its bread? is only #bj feet1 s t x n>r[s upw>d z mu* z #fj feet 9 a v]tical height ( #cej feet4 ,its contraction 9 wid? dur+ ! la/ tw5ty feet is /ill m rapid1 & 9 ! la/ few y>ds x dim9i%es to two or ?ree feet1 & has a r\nd$ top ov] :i* ! /rata are b5t upw>d4 ,! accompany+ section 7,fig4 #bdc7 across ! upp] "p ( ! dyke w make ^! features cle>4 ,illu/ration3 ,fig4 #bdc4--,section across ! extreme upp] limit ( ,clevel& ,dyke1 on ! scale ( #bj feet to "o in* 7,mr4 ,g4 ,b>r[74 a a1 ,jurassic %ales1 etc42 b1 ,dyke4 ,illu/ration3 ,fig4 #bdd4--,upp] limit ( ,clevel& ,dyke 9 qu>ry ne> ,cockfield 7aft] ,mr4 ,teall74 a a1 ,c>bonif]\s %ales2 b1 dyke4 ,fur!r to ! we/ an exposure ( ! upp] limit ( ! dyke has be5 describ$ & figur$ by ,mr4 ,teall4 ,9 #ahhb1 at "o ( ! ,cockfield qu>ries 7,fig4 #bdd71 ! dyke 0 se5 to t]m9ate upw>ds v abruptly 9 ! =m ( a l[ & some:at irregul> dome1 ov] :i* ! ,coal-measure %ales pass$ )\t any fracture1 & only ) a slight upw>d ar*+4#ahi ,footnote #ahi3 ,qu>t4 ,j\r4 ,geol4 ,soc4 xl4 p4 #baj4 ,ne> ! o!r or nor?-we/]n t]m9ation ( ?is great dyke1 simil> evid5ce is f\nd ( an unev5 upp] limit4 ,aft] an int]rupt$ c\rse ?r\gh ! ,al/on moors1 ! dyke rea*es ! gr\nd t slopes ea/w>d f ! edge ( ! ,cross ,fell esc>pm5t4 ,its highe/ visible outcrop is at a height ( #agjj feet4 ,b we/w>ds f t po9t ! dyke disappe>s "u ! ,c>bonif]\s rocks1 & does n em]ge along ! front ( ! great esc>pm5t t desc5ds ^u ! valley ( ! ,ed51 :]e among ! nak$ sc>ps ( rock x w\ld unque/ionably be visible if x rea*$ ! surface4 ,its upp] edge mu/ rapidly desc5d some:]e beh9d ! face ( ! esc>pm5t1 = ! igne\s rock crops out a little to ! we/ ( ! foot ( ! cliff1 ab\t #ajjj feet bel[ ! po9t :]e x is la/ se5 on ! hills above4 ,"h ! top ( ! dyke has a v]tical drop ( n less ?an #ajjj feet1 9 a horizontal di/ance ( five miles1 z %[n 9 ,fig4 #bde1 :i* has be5 drawn = me by ,mr4 ,j4 ,g4 ,good*ild4 ,x w be obs]v$ t 9 ^! sections 7,figs4 #bda1 #bdb & #bde7 !re is a curi\sly approximate co9cid5ce betwe5 ! inequalities 9 ! upp] surface ( ! dyke & ^? 9 ! =m ( ! ov]ly+ gr\nd4 ,! co9cid5ce is too m>k$ & too (t5 repeat$ to be m]ely accid5tal4 ,:e!r ! anci5t topographical features _h any influ5ce 9 det]m9+1 by cool+ or o!rwise1 ! limit ( ! upw>d rise ( ! lava1 or :e!r ! dyke1 ev5 ?\gh conceal$1 has affect$ ! progress ( ! d5udation ( ! gr\nd ov]ly+ x1 is a "q wor?y ( full] inve/igation4 ,illu/ration3 ,fig #bde4--,section along ! c\rse ( ! ,clevel& ,dyke across ! ,cross ,fell esc>pm5t4 ,! %ad$ "p %[s ! position ( ! dyke1 ! un%ad$ "p ov]ly+ x m>ks :]e ! dyke does n rea* ! surface4 ,scale ( "o in* to "o mile4 #aa4 ,,kn[n ,,v]tical ,,ext5sion ,closely connect$ ) ! det]m9ation ( ! upp] limit rea*$ by ! dykes1 is ! total v]tical di/ance to :i* !y c be trac$4 ,( c\rse1 ! dep? ( ! orig9al res]voir ( molt5 rock :i* suppli$ !m rema9s unkn[n1 & probably undiscov]able4 ,b x is possible1 9 _m cases1 to det]m9e at lea/ ! inf]ior limit ( ! ?ickness ( rock ?r\gh :i* ! molt5 mat]ial ( ! dykes has asc5d$4 ,along ! great basalt-esc>pm5ts ( ,mull & ,skye1 ! asc5t ( dykes f base to summit may (t5 be obs]v$4 ,?us1 on ! cliffs ( ,dunvegan ,head1 on ! we/ coa/ ( ,skye1 :i* rise out ( ! sea to a height ( ab\t #ajjj feet1 sev]al dykes may be obs]v$ ris+ ?r\gh ! :ole s]ies ( basalts up to ! cre/ ( ! precipice4 ,9 ! d>k gabbro hills ( ! same isl&1 num]\s dykes may be se5 climb+ f ! gl5s "r up ! /eep rugg$ acclivities & ov] ! cre/s1 ?r\gh a v]tical ?ickness ( m ?an #cjjj feet ( rock 7,fig4 #ccc74 ,! dykes :i* cross ,lo* ,lomond1 & asc5d ! hills on ei!r side ( t deep depression1 mu/ rise ?r\gh at lea/ z great a ?ickness4 ,b :]e a k ( ! geological /ructure ( ! gr\nd enables u to e/imate ! bulk ( ! successive rock-=mations :i* und]lie ! surface1 x c be %[n t ! lava asc5d$ ?r\gh a mu* great] dep? ( rock4 ,measurem5ts ( ?is k9d c be/ be made t[>ds ! ea/]n end ( ! ,clevel& dyke1 :]e ! diff]5t s$im5t>y gr\ps h n be5 s]i\sly di/urb$1 & :]e1 f natural sections & artificial bor+s1 _! ?icknesses are capable ( satisfactory computation4 ,! highe/ b$ ( ! ,jurassic s]ies any:]e t\*$ by ! dyke is ! ,cornbra%4 ,x is c]ta91 !re=e1 t ! igne\s rock rises ?r\gh all ! subjac5t memb]s ( ! ,jurassic s]ies up to t horizon4 ,!re c be no d\bt also t ! ,trias & ,magnesian ,lime/one cont9ue 9 _! normal ?ickness und]nea? ! ,jurassic /rata4 ,to :at ext5t ! ,coal-measures exi/ "u ,clevel& has n be5 asc]ta9$2 possibly !y h be5 entirely d5ud$ f t area1 z f ! gr\nd to ! we/4 ,b ! ,mill/one ,grit & ,c>bonif]\s ,lime/one probably ext5d ov] ! di/rict 9 full developm5t2 & bel[ !m !re mu/ lie a va/ dep? ( ,upp] & ,l[] ,silurian /rata1 probably also ( /ill old] ,palozoic rocks & b5ea? all ! ?ick ,ar*an plat=m4 ,tabulat+ ^! successive geological =mations1 & tak+ only ! asc]ta9$ ?ickness ( ea* 9 ! di/rict1 we f9d t !y give ! results %[n 9 ! subjo9$ table4#aij ,footnote #aij3 ,drawn up = me by ,mr4 ,g4 ,b>r[4 ,,/rata ,,cut ,,by ,,! ,,clevel& ,,dyke ,cornbra%-- ,feet4 ,l[] ,oolite & ,upp] ,lias1 z prov$ by bore-hole on ,g]rick ,moor1 #iej ,middle & ,l[] ,lias1 asc]ta9$ f measurem5t ( cliff-sections & f m9+ op]ations to be m ?an #hej ,new ,r$ ,s&/one & ,m>l1 f\nd by bor+ close to ! ,tees to exce$ #a1fjj ,magnesian ,lime/one1 at lea/ #ejj ,coal-measures1 possibly abs5t #j ,mill/one ,grit1 n less ?an #ejj ,c>bonif]\s ,lime/one s]ies at lea/ #c1jjj ,silurian rocks1 probably n less ?an #aj1jjj ------- #ag1djj ,!re is ?us evid5ce t ?is dyke has ris5 ?r\gh probably m ?an ?ree miles ( /ratifi$ rocks4 ,h[ mu* deep] /ill lay ! orig9al res]voir ( molt5 mat]ial t suppli$ ! dyke1 we h at pres5t no means ( comput+4 #ab4 ,,evid5ce ,,z ,,to ,,movem5t ,,( ,,! ,,molt5 ,,rock ,,9 ,,! ,,fissures ,x is usual to speak ( ! molt5 mat]ial ( ! dykes z hav+ ris5 v]tically )9 ! fissures4 ,& d\btless1 on ! :ole1 ! expression is suffici5tly accurate4 ,9 ! case ( su* long dykes z ^? ( ,c5tral ,scotl& & ! ,nor? ( ,engl&1 :]e ! petrographical "* ( ! mat]ial rema9s s uni=m ?r\gh\t1 x is obvi\s t ! &esite or dol]ite _c h come f a m]e s+le pipe l a volcanic orifice4 ,nor c we easily und]/& h[ x c\ld h be5 suppli$ ev5 f a s]ies ( su* pipes4 ,! g5]al aspect & /ructure ( ! dykes sugge/ t ! fissures 7 r5t s pr(\ndly 9 ! cru/ ( ! e>? z to rea* d[n to a res]voir ( molt5 rock :i* /raightway rose 9 !m4 ,! ro( ( su* a res]voir1 h[ev]1 may h be5 irregul> & unev51 s t a fissure ne$ n h trav]s$ x cont9u\sly1 b may h only t\*$ its upw>d project+ vaults4 ,h5ce gaps w\ld arise 9 ! cont9uity ( ! dyke-mat]ial4 ,! asc5t ( lava f a l9e ( su* sep>ate op5+s along a fissure w\ld necess>ily involve lat]al z well z v]tical movem5ts 9 ! molt5 mass :i* w\ld be =c$ along ! op5 r5t until ! sev]al /reams unit$ & fill$ x up4 ,we might !re=e expect some:]e to f9d in/ances ( fl[-/ructure 9 ! dykes po9t+ to ^! movem5ts4 ,i h already ref]r$ to ! l9es ( amygdales frequ5tly notic$ 9 dykes1 especially t[>ds ! c5tre4 ,occasionally ^! /eam-vesicles may be obs]v$ to be drawn out 9 "o g5]al direction indicative ( ! tr5d ( motion ( ! molt5 rock4 ,"s ( ! be/ examples ( ?is feature :i* h come "u my obs]vation occur among ! tra*ytic dykes ( ! s\?-ea/ coa/ ( ,skye betwe5 ,kyle ,rhea & ,lo* na ,daal1 :]e !y h be5 mapp$ & c>efully inve/igat$ by ,mr4 ,cl\gh1 :o has conduct$ me ov] ! sections4 ,9 "s ( ^! dykes1 z already n>rat$1 ! m>g9al portions display a f9ely sph]ulitic /ructure1 ! small pea-l sph]ulites be+ gr\p$ into f9e ribs or rods4 ,x is also obs]vable t ! /eam-vesicles :i* may reta9 _! sph]ical =ms 9 ! c5tre are elongat$ 9 ! same direction z ! r[s ( sph]ulites4 ,:]e ?is l9eation is develop$ v]tically1 x no d\bt po9ts to ! v]tical asc5t ( ! lava betwe5 ! two walls ( ! fissure4 ,b 9 o!r examples1 ! elongation is ne>ly horizontal1 & betwe5 ! two positions ,mr4 ,cl\gh has regi/]$ _m int]m$iate tr5ds4 ,x w\ld ?us appe> t 9 "s places ! lava has c]ta9ly fl[$ lat]ally betwe5 ! fissure-walls4 ,moreov]1 ! tr5d ( ! sph]ulitic rods & ( ! amygdales is f\nd to v>y 9 closely adjo9+ planes at diff]5t di/ances f ! m>g91 z if aft] ! out] portions ( ! dyke _h consolidat$ into position1 !re 0 /ill movem5t en\gh to drag ! r[s ( sph]ulites & vesicles up or d[n along ! tr5d ( ! fissure4 ,mr4 ,cl\gh has obs]v$ t 9 "s dykes1 :ile ! amygdaloidal vesicles are l>ge & unde=m$ 9 ! c5tre1 !y become elongat$ & incl9$ d[nw>d 9 ! direction ( ! m>g91 z if ! c5tral portions _h n only rema9$ fluid long] ?an ! re/1 b _h a t5d5cy to rise upw>ds 9 ! fissure1 ?\gh !re 0 obvi\sly less motion aft] ^! c5tral vesicles appe>$ ?an 9 ! m>g9al p>ts :]e ! vesicles are s mu* drawn out4 #ac4 ,,bran*+ ,,dykes ,,& ,,ve9s ,x might h be5 anticipat$ t ! uprise ( su* abundant masses ( molt5 rock1 9 s _m long & wide fissures1 w\ld g5]ally be att5d$ ) ! intrusion ( ! same mat]ial into lat]al r5ts & irregul> op5+s1 s t ea* dyke w\ld h a k9d ( fr+e ( (f%oots or processes /rik+ f x into ! surr\nd+ gr\nd4 ,x might h be5 expect$ also t dykes w\ld (t5 bran*1 & t ! arms w\ld come toge!r aga9 & enclose portions ( ! rocks ?r\gh :i* !y rise4 ,b 9 reality su* excresc5ces & bifurcations are ( comp>atively r>e occurr5ce4 ,z a rule1 ea* dyke is a m]e wall ( igne\s rock1 ) little m projection or ramification ?an may be se5 9 a /one field-f5ce4 ,among ! %ort1 n>r[ & irregul> dykes ( ! greg>i\s type bran*+s are occasionally se51 & 9 "s di/ricts are extraord9>ily abundant4 ,b among ! great s+le dykes su* irregul>ities are f> less common ?an might h be5 look$ =4 ,a few *>act]i/ic examples f ea* type ( dyke may "h be giv54 ,illu/ration3 ,fig4 #bdf4--;,bran*+ portion ( ! great ,dyke ne> ,hawick 7l5g? ab\t "o mile74 ,illu/ration3 ,fig4 #bdg4--;,bran*+ ,dyke at foot ( ,gl5 ,artney 7l5g? ab\t f\r miles74 ,! ,clevel& dyke1 :i* 9 s _m respects is typical ( ! great solit>y dykes ( ! c\ntry1 has be5 trac$ = _m miles )\t ! appe>ance ( a s+le (f%oot ( any k9d4 ,yet "h & !re along its c\rse1 x dep>ts f its usual regul>ity4 ,z x crosses ! ,c>bonif]\s tracts ( ,durham & ,cumb]l&1 !re appe> ne> its c\rse lat]al masses ( eruptive rock1 mo/ ( :i* d\btless belong to ! mu* old] ,:9 ,sill4 ,b !re is at lea/ "o locality1 at ,bolam ne> ,cockfield1 9 ! c\nty ( ,durham1 :]e ! dyke1 cross+ ! ,mill/one ,grit1 sudd5ly exp&s into a boss1 & imm$iately contracts to its usual dim5sions4 ,ar\nd ?is knot sev]al %ort dykes or ve9s seem to radiate f x4 ,! dyke has be5 qu>ri$ "h1 & its relations to ! surr\nd+ /rata h be5 laid b>e1 z w be aga9 ref]r$ to a little fur!r on4#aia ,footnote #aia3 ,?is locality 0 well describ$ by ,s$gwick1 9 8 e>ly pap] on ,trap-,dykes 9 ,york%ire & ,durham1 ,trans4 ,cambridge ,phil4 ,soc4 ii4 p4 #bg4 ,among ! great p]si/5t dykes ( ,scotl& ! abs5ce ( bifurcation & lat]al (f%oots (f]s a /rik+ contra/ to ! behavi\r ( ! dykes 9 ^? di/ricts :]e !y are small 9 size & _m 9 numb]4 ,b exceptions to ! g5]al rule may be ga!r$4 ,?us ! ,eskdale dyke is flank$ at ,wat ,c>rick ) a l>ge lat]al ve91 :i* is almo/ c]ta9ly connect$ ) ! ma9 fissure4 ,! ,hawick & ,*eviot dyke splits up on ! hill imm$iately to ! ea/ ( ! t[n ( ,hawick1 s5ds (f "s bran*es1 & !n resumes its normal c\rse 7,fig4 #bdf74 ,aga91 "o ( ! two ne>ly p>allel dykes :i* run f ,lo*goilhead across ,b5 ,l$i into ,gl5 ,artney bifurcates at ! foot ( t valley1 its nor!rn limb 7ab\t two miles long7 spe$ily dy+ out1 & its s\!rn bran* ?r[+ (f ano!r lat]al ve91 & !n cont9u+ ea/w>d z ! ma9 dyke 7,fig4 #bdg74 ,9 ! di/ricts ( greg>i\s dykes1 h[ev]1 abundant in/ances may be f\nd ( dykes t bran*1 & ( o!rs t lose ! p>allelism ( _! walls1 become irregul> 9 bread?1 direction1 & incl9ation1 s z to pass into ^? intrusive =ms t are m prop]ly class$ z ve9s4 ,excell5t illu/rations ( bifurcat+ dykes may be obs]v$ along ! %ores ( ! ,fir? ( ,clyde1 p>ticul>ly on ! ea/]n coa/-l9e ( ! isle ( ,arran4 ,! v5\s "* has become famili> to geologi/s f ! sket*es giv5 by ,maccullo* f ! l[] p>ts ( ! cliffs ( ,trott]ni% 9 ,skye4#aib ,/ill m /rik+ examples are to be se5 9 ! break]-beat5 cliffs ( ,ardnamur*an4 ,! pale ,second>y lime/ones & calc>e\s s&/ones ( t locality are trav]s$ by a s]ies ( d>k basic ve9s1 & ! contra/ ( t9t betwe5 ! two k9ds ( rock is s m>k$ z ev5 to cat* ! eye ( casual t\ri/s 9 ! pass+ /eamboats4 ,! ve9s v>y 9 wid? f less ?an an in* to sev]al feet or y>ds4 ,!y run 9 all directions & int]sect ea* o!r1 =m+ su* a confus$ m$ley z requires "s pati5ce on ! "p ( ! geologi/ :o w\ld foll[ out ea* indep5d5t ribbon ( inject$ mat]ial 9 its c\rse up ! cliffs1 or /ill m1 w\ld sket* _! ramifications 9 8 note-book4 ,a good1 ?\gh p]haps some:at exagg]at$1 illu/ration ( _! g5]al "* 0 giv5 by ,maccullo*4#aic ,! accompany+ figure 7,fig4 #bdh7 is less s5sational1 b repres5ts ) z mu* accuracy z ,i c\ld rea*1 ! network ( ve9s ne> ! foot ( ! cliffs4 ,"o conspicu\s gr\p ( ve9s1 :i*1 se5 f a di/ance1 looks l a rude sket* ( a lug-sail trac$ 9 black outl9e ^u a pale gr\nd1 is kn[n to ! boatm5 z ,m',niv5's ,sail4 ,ano!r admirable locality = ! /udy ( dykes & tortu\s ve9s is ! nor!rn coa/ ( ! ,s\nd ( ,soa1 :]e an extraord9>y numb] ( injections trav]se ! ,torridon ,s&/ones on :i* ! plateau-basalts re/ 7,fig4 #cbc74 ,footnote #aib3 ,we/]n ,isl&s1 plate xvii4 ,footnote #aic3 ,op4 cit4 plate xxxiii4 ,fig4 #a4 ,z a g5]al rule1 ! n>r[] ! ve9 ! f9] 9 gra9 is ! rock ( :i* x consi/s4 ,?is compact d>k homog5e\s mat]ial has commonly pass$ by ! "n ( basalt4 ,its m9ut5ess ( texture probably 9 mo/ cases arises f local rapidity ( cool+1 & x is d\btless ! same sub/ance :i*1 :]e 9 l>g] mass 9 ! imm$iate neighb\rhood1 has solidifi$ z "o ( ! o!r pyrox5e-plagioclase-magnetite rocks4 ,) reg>d to ! places :]e su* abundant tortu\s ve9s are m especially develop$1 ,i may rem>k t !y are p>ticul>ly prom95t "u a ?ick ov]ly+ mass ( erupt$ rock1 su* z a great intrusive %eet1 or ! b$d$ basalts ( ! plateaux1 or :]e !re is good reason to believe t su* a deep cov]1 ?\gh n[ remov$ by d5udation1 once ov]spread ! area 9 :i* !y appe>4 ,x w be %[n 9 ! sequel t su* horizons h be5 peculi>ly liable to intrusions ( igne\s mat]ial ( v>i\s k9ds1 & at _m diff]5t int]vals1 dur+ ! volcanic p]iod4 ,a ?ick cake ( cry/all9e rock seems to h (f]$ su* resi/ance to ! uprise ( molt5 mat]ial ?r\gh x1 t :5 ! subt]ranean en]gy 0 n suffici5t to r5d x op5 by great fissures1 & ?us give rise to dykes1 ! lavas 7 ei!r =c$ into su* irregul> cracks z 7 made p>tly 9 ! s(t] rocks und]nea? & p>tly 9 ! cake itself1 or f\nd escape along pre-exi/+ divisional planes4 ,9 ,ardnamur*an1 r\nd ! ,cuill9 ,hills ( ,skye1 & 9 ,rum1 ! ov]ly+ resi/+ cov] n[ consi/s ma9ly ( gabbro %eets4 ,9 ! ea/ ( ,skye1 9 ,eigg1 & 9 ,antrim1 x is made up ( ! ?ick mass ( ! plateau-basalts4 ,illu/ration3 ,fig4 #bdh4--;,basic ve9s trav]s+ second>y lime/one & s&/one on ! coa/ cliffs1 ,ardnamur*an4 #ad4 ,,connection ,,( ,,dykes ,,) ,,sills ,e field-geologi/ is aw>e h[ seldom he c actually f9d ! v5t or pipe up :i* rose ! igne\s rock t suppli$ ! mat]ial ( sills & laccolites4 ,he might well be p>don$ 7 he to anticipate t1 9 a di/rict mu* trav]s$ by dykes1 !re %\ld be _m examples ( intrusive %eets & frequ5t opportunities ( trac+ ! connection ( su* %eets ) ! fissures f :i* _! mat]ial might be suppos$ to h be5 suppli$4 ,b su* an expectation is s+ul>ly disappo9t$ by an actual exam9ation ( ! ,t]ti>y volcanic region ( ,brita94 ,t !re are _m intrusive %eets belong+ to ! great volcanic p]iod ) :i* ,i am n[ deal+1 ,i %all endeav\r to %[ 9 ! sequel4 ,b x is q c]ta9 t ?\gh ^! %eets h ( c\rse ea* _h its subt]ranean pipe or fissure ( supply1 !y c only 9 r>e in/ances be directly trac$ to ! sy/em ( dykes4 ,on ! o!r h&1 ! di/ricts :]e great s+le dykes are mo/ conspicu\s1 are = ! mo/ "p free f intrusive %eets1 except ^? ( mu* old] date1 l ! ,c>bonif]\s ,:9 ,sill ( ,durham & ^? ( ,l9li?g[%ire1 ,/irl+%ire & ,fife4 ,yet a few int]e/+ examples ( ! relation ( dykes to %eets h be5 notic$ among ,briti% ,t]ti>y volcanic rocks4 ,! e>lie/ obs]v$ in/ances 7 ^? figur$ & describ$ by ,maccullo*4 ,among !m "o has be5 famili> to geologi/s f hav+ done duty 9 text-books ( ! sci5ce = m ?an half a c5tury4 ,i allude to ! diagram ( ,trap & ,s&/one ne> ,sui%ni%4#aid ,9 t draw+ sev5 dykes are %[n z ris+ v]tically ?r\gh ! horizontal s&/one1 & m]g+ into a ?ick ov]ly+ mass ( trap4 ,! au?or 9 8 explanation leaves x an op5 "q :e!r ! intrud+ mat]ial has asc5d$ f bel[ & ov]fl[$ ! /rata1 or has desc5d$ f ! mass1 ?\gh f ! language he uses 9 8 text we may inf] t he 0 incl9$ to reg>d ! ov]ly+ body z ! s\rce ( ! ve9s bel[ x4#aie ,footnote #aid3 ,we/]n ,isl&s ( ,scotl&1 pl4 xiv4 ,fig4 #d4 ,footnote #aie3 ,op4 cit4 vol4 i4 pp4 #chd1 #che4 ,illu/ration3 ,fig4 #bdi4--,section %[+ ! connection ( a ,dyke ) an ,intrusive ,%eet1 ,po9t ( ,suisni%1 ,skye4 g1 ,granophyre ( ,c>n ,de>g2 f1 simil> rock1 :i* appe>s ea/w>d "u ! sill 7d72 e1 intrusive %eet ( f9e-gra9$ basalt2 d1 intrusive %eet or sill ( co>se dol]ite1 #bjj feet ?ick at its maximum1 & rapidly ?9n+ out2 c1 dyke or pipe ( f9] gra9 ?an d2 b1 yell[i%-br[n %aly s&/ones1 & a1 d>k s&y %ales 7,lias74 ,! section giv5 by ,maccullo*1 h[ev]1 does n q accurately repres5t ! facts4 ,! n>r[ dykes !re drawn h no connection ) ! ov]ly+ %eet1 b are "p ( ! abundant s]ies ( basaltic dykes f\nd all ov] ,skye4 ,! fe$] ( ! gabbro sill 0 presumably ! broad dyke :i* desc5ds ! /eep bank imm$iately on ! s\!rn front ( ,c>n ,de>g 7#fcf feet high74 ,! accompany+ figure 7,fig4 #bdi7 %[s :at seem$ to me to be ! /ructure ( ! locality1 b ! actual junction ( ! dyke & %eet is conceal$ "u ! talus ( ! slope4#aif ,i %all h occasion 9 a lat] ,*apt] to ref] aga9 to ?is section 9 connection ) ! hi/ory ( intrusive %eets1 & also to cite f ! neighb\r+ isl& ( ,raasay ano!r good example ( ! same relation betwe5 dyke & sill4 ,footnote #aif3 ,9 m rec5tly survey+ ?is gr\nd1 ,mr4 ,h>k] has be5 l$ to reg>d ! co>se sill z indep5d5t ( ! o!r intrusions1 & z almo/ c]ta9ly lat] ?an ! basalt-%eets ( ! same locality4 ,:5 x rea*es ! base ( ^! sills x turns s z to pass b5ea? !m z a gabbro-sill1 :i* is conspicu\s ne> ! summit ( ,c>n ,de>g4 ,x runs we/w>d = "s di/ance1 almo/ imm$iately break+ across ! b$d+ s z to leave ! basalt1 & rapidly tap]+ until x dies out4 ,s$gwick1 9 ! pap] above quot$1 gave an acc\nt & figure ( ! expansion ( ! ,clevel& dyke at ,bolam1 to :i* allusion has already be5 made4 ,he %[$ t f a "p ( ! dyke :i* is unusually contract$ a great lat]al ext5sion ( ! igne\s rock takes place on ei!r side ov] b$s ( %ale & coal4 ,:ile 9 ! dyke ! prisms are z usual direct$ horizontally inw>d f ! two walls1 ^? 9 ! connect$ %eet are v]tical1 & desc5d ^u ! surface ( highly indurat$ /rata on :i* ! %eet re/s4 ,! mo/ important examples kn[n to me are ^? :i* occur 9 ! coal-field ( ,/irl+%ire4 ,9 t "p ( ! c\ntry1 ! rem>kable gr\p ( dykes already ref]r$ to1 ly+ ne>ly p>allel to ea* o!r & f half a mile to ab\t ?ree miles ap>t1 runs 9 a g5]al ea/ & we/ direction4 ,f "o ( ^! dykes no few] ?an f\r sills /rike (f into ! surr\nd+ ,coal-measures4 ,! l>ge/ ( !m /ret*es s\?w>ds = ?ree miles1 b ! same rock is probably cont9u$ 9 a succession ( deta*$ areas :i* spread we/w>ds ?r\gh ! coal-field & circle r\nd to ne> ! two we/]n %eets t proce$$ f ! same dyke4 ,ano!r ?ick mass ( simil> rock ext5ds on ! nor? side ( ! dyke = two & a half miles d[n ! valley ( ! riv] ,avon4 ,^! v>i\s processes1 atta*$ to or div]g+ f ! dyke1 are unque/ionably intrusive %eets1 :i* occupy diff]5t horizons 9 ! ,c>bonif]\s s]ies4 ,! "o on ! nor? side has ins]t$ itself a little above ! top ( ! ,c>bonif]\s ,lime/one s]ies4 ,^? on ! s\? side lie on diff]5t levels 9 ! ,coal-measures1 or1 r1 !y pass transgressively f "o plat=m to ano!r 9 t gr\p ( /rata4 ,illu/ration3 ,fig4 #bej4--,section to %[ ! connection ( a ,dyke ) an ,intrusive ,%eet1 ,/irl+%ire ,coal-field4 a1 ,dyke 9 l9e ( fault2 b1 ,sill trav]s+ & alt]+ ! coal2 i1 ,slaty-b& ,iron/one4 ,no ess5tial diff]5ce c be detect$ by ! nak$ eye betwe5 ! mat]ial ( ! dyke & t ( ! %eets4 ,if a s]ies ( specim5s f ! diff]5t exposures 7 mix$ up1 x w\ld be impossible to sep>ate ^? ( ! dyke f ^? ( ! %eets4 ,a microscopical exam9ation ( ! specim5s likewise %[s t !y are p]fectly id5tical 9 composition & /ructure1 be+ *iefly ref]able to rocks ( ! dol]ite1 b p>tly ( ! ?oleiite type4 ,i h !re=e little d\bt t ^! rem>kable app5dages to ?is dyke are truly (f%oots f x1 & are n to be class$ ) ! g5]al mass ( ! sills ( ,c5tral ,scotl&1 :i* are ( ,c>bonif]\s1 p>tly ( ,p]mian1 age4 ,! accompany+ diagrammatic section 7,fig4 #bej7 expla9s ! geological /ructure ( ! gr\nd4 ,an int]e/+ & important fact rema9s to be /at$ 9 connection ) ^! %eets4 ,!y are trav]s$ by "s ( ! o!r ea/ & we/ dykes4 ,?is is p>ticul>ly obs]vable 9 ! case ( ! %eet :i* ext5ds nor?w>ds f ! dyke ?r\gh ! p>i% ( ,torphi*54 ,two well-m>k$ dykes c be se5 runn+ we/w>ds among ! ridges ( ! %eet4 ,x is obvi\s1 !re=e t ^! p>ticul> dykes are y\ng] ?an ! %eet4 ,b1 z w be %[n 9 ! sequel1 !re is abundant evid5ce t all ! dykes ( a di/rict are n ( "o eruption4 ,! int]section ( "o eruptive mass by ano!r does n necess>ily imply any long int]val ( "t betwe5 !m4 ,!y m>k successive1 b x may be rapidly successive1 manife/ations ( volcanic action4 ,h5ce ! cutt+ ( ! %eets by o!r dykes does n invalidate ! id5tification ( ^! %eets z extravasations f ! great dyke by :i* !y are b\nd$4 #ae4 ,,int]section ,,( ,,dykes ,illu/ration3 ,fig4 #bea4--;,int]section ( ,dykes 9 b$d$ basalt1 ,callia* ,po9t1 ,mull4 ,innum]able in/ances may be cit$1 :]e "o dyke1 or "o set ( dykes1 cuts across ano!r4 ,to "s ( ^! ,i %all ref] 9 discuss+ ! data = e/imat+ ! relative ages ( dykes4 ,9 consid]+ ! int]section f ! po9t ( view ( geological /ructure1 we are /ruck ) ! clean %>p way 9 :i* x s g5]ally takes place4 ,! r5ts into :i* ! y\ng] dykes h be5 inject$ seem1 z a rule1 n to h be5 s5sibly influ5c$ 9 wid? & direction by ! old] dykes1 b g "r across !m4 ,h5ce ! y\ng] dykes reta9 _! usual bread? & tr5d 7,fig4 #bea74 ,9 try+ to asc]ta9 ! relative ages ( su* dykes we obta9 a valuable clue 9 /udy+ ! respective *ill$ edges ( ! two int]sect+ masses1 z has already be5 po9t$ out4 ,n only d dykes cross ea* o!r1 b /ill m is ?is ! case among ! n>r[] tortu\s intrusions kn[n z ,ve9s 7,fig4 #beb74 ,among ! illu/rations :i* ! dykes ( ! ,inn] ,hebrides supply ( ^! features "o fur!r *>act]i/ic example may be cull$ f ! %ore ( ,skye1 ne> ,broad=d1 :]e ! g5tly-incl9$ %eets ( ,lias lime/one are trav]s$ by ?ree sy/ems ( dykes 7,fig4 #bec74 ,"o ( ^! sy/ems runs 9 a ,n4,w4 or ,n4,n4,w4 direction1 a second foll[s a m ne>ly ea/]ly tr5d1 :ile ! ?ird & y\nge/ runs ne>ly nor? & s\?4 ,illu/ration3 ,fig4 #beb4--;,basalt ,ve9s trav]s+ b$d$ dol]ites1 ,kildonan1 ,eigg4 ,illu/ration3 ,fig4 #bec4--;,gr\nd-plan ( int]sect+ ,dykes 9 ,lias lime/one1 ,%ore1 ,h>rabol1 ,ea/ ( ,broad=d1 ,skye4 #af4 ,,dykes ,,( ,,m ,,?an ,,"o ,,9-,,fill+ ,! int]sections ( dykes prove t ! process ( fissur+ 9 ! e>?'s cru/ took place at m ?an "o p]iod1 & prep>e u = ! reception ( evid5ce t ! same l9e ( fissure might be aga9 re-op5$1 ev5 aft] x _h be5 fill$ ) molt5 mat]ial4 ,num]\s in/ances h n[ be5 accumulat$ 9 :i* dykes are n s+le or simple intrusions1 b :]e ! orig9al dyke-fissure has be5 re-op5$ & has be5 invad$ by successive upris+s ( lava4#aig ,comp\nd dykes h ?us be5 =m$1 consi/+ ( two or m p>allel b&s ( simil> or dissimil> rock4 ,footnote #aig3 ,see an example figur$ by ,maccullo*1 ,we/]n ,isles1 plate xviii4 ,fig4 #a4 ,:ile x is n difficult to conceive ( ! re-op5+ ( a v]tical fissure dur+ t]re/rial /ra91 & ! injection into x ( lat] intrusions ( a volcanic magma1 x is n s easy to und]/& ! me*anism :]e ! l9e ( weakness has be5 slightly incl9$ or horizontal1 & :]e1 consequ5tly1 !re has be5 ! enorm\s sup]9cumb5t pressure ( ! ov]ly+ "p ( ! e>?'s cru/ to ov]come4 ,yet g5tly incl9$ comp\nd dykes exhibit _! p>allel b&s ) h>dly less regul>ity ?an d ^? t are v]tical4 ,! difficulty ( explanation is felt mo/ /rongly 9 ! attempt to realize ! orig9 ( ! comp\nd sills describ$ 9 ,*apt] xlviii4 ,9 ! re-op5+ ( dyke-fissures ! lat] intrusions h g5]ally tak5 place along ! walls1 or :]e ! dykes 7 already comp\nd1 betwe5 "s ( ! compon5t b&s4 ,less frequ5tly ! fir/ dyke has be5 split op5 along ! middle1 & a second injection has =c$ its way along ! r5t4 ,( ! fir/ ( ^! two types1 num]\s in/ances h n[ be5 obs]v$ 9 ! ,we/ ( ,scotl&4 ,if ! portion ( a comp\nd dyke expos$ at ! surface be limit$ 9 ext5t1 we may be unable to det]m9e :i* is ! old] ( two p>allel b&s ( igne\s rock1 ?\gh ! fact t !y pres5t to ea* o!r ! usual f9e-gra9$ edge due to m rapid cool+1 %[s t !y are n "o b two dykes1 belong+ to di/9ct eruptions4 ,s f> z ,i h notic$1 :]e "o ( ! dykes c be cont9u\sly trac$ = a consid]able di/ance1 ! o!r is comp>atively %ort4 ,i inf] t ! %ort] "o is ! y\ng] ( ! two4 ,9 ! ,/ra? di/rict ( ,skye1 ,mr4 ,h>k] has rec5tly obs]v$ t _m ( ! basic dykes1 bo? ^? old] & ^? y\ng] ?an ! granophyre protrusions1 are d\ble1 triple or multiple4 ,?us 9 a conspicu\s dyke1 m ?an #ajj feet wide1 to ! s\?-ea/ ( ,lo* ,kil*ri/1 belong+ to ! old] s]ies1 he has detect$ at lea/ six contigu\s dykes :i* z !y are trac$ s\?-ea/w>d1 9 spite ( _! int]ruption by ! ,be9n an ,dubhai* granite1 c be se5 to sep>ate & take diff]5t c\rses1 or successively die out4 ,he rem>ks1 fur!r1 t _m cases ( app>5t bifurcation ( dykes are really due to ! sep>ation ( di/9ct dykes :i* h run = "s di/ance 9 "o fissure4 ,sometimes app>5t v>iations 9 ! wid? ( a dyke are to be expla9$ by ?is dy+ out ( "o memb] ( a d\ble dyke4 ,^! multiple dykes are less easily detect$ 9 ! new] ?an ! old] set1 ow+ to great] uni=mity ( li?ological type 9 ! preval5t k9ds & to ! frequ5t abs5ce ( *ill$ selvages4#aih ,an example ( a comp\nd basic dyke cutt+ ! cre/ ( ! gabbro-mass ( ! ,cuill9 ,hills is %[n 9 ,fig4 #ccc4 ,footnote #aih3 ,,ms4 notes suppli$ by ,mr4 ,h>k]4 ,in/ances ( ! second type ( comp\nd dykes are less common4 ,"h1 in/ead ( be+ re-op5$ along "o ( ! walls1 ! fissure has be5 ruptur$ along ! c5tre ( ! dyke1 & a second injection ( molt5 mat]ial has !n tak5 place4 ,?is /ructure may be obs]v$ :]e ! mat]ials ( ! comp\nd dyke are on ! :ole simil>1 su* z v>ieties ( dol]ite1 basalt1 diabase or &esite4 ,9 ^! cases ! rock ( ! c5tral dyke is g5]ally r f9e-gra9$1 sometimes decid$ly porphyritic1 & (t5 a true basalt4 ,:]e broad en\gh to %[ ! diff]5ce ( texture betwe5 m>g9 & c5tre1 x exhibits ! usual close gra9 along its edges1 indicative ( quick] cool+4 ,! old] dyke pres5t+ no su* *ange at its junction ) ! y\ng]1 0 obvi\sly already cool$ & consolidat$ be=e its rupture4 ,:il/ ! c5tre ( a dyke has occasionally prov$ to be a l9e ( weakness :i* has giv5 way "u int5se /ra9s 9 ! t]re/rial cru/1 ?is rupture & ! accompany+ or subsequ5t asc5t ( molt5 mat]ial 9 ! re-op5$ fissure may sometimes h be5 includ$ z phases ( "o connect$ volcanic episode4 ,9 ^? in/ances1 = example1 :i* h be5 above describ$1 :]e a c5tral vitre\s b& has ris5 along ! he>t ( a dyke1 ! petrographical aff9ities ( ! rocks may be s close z to sugge/ t al?\gh ! ma9 dyke _h consolidat$ & _h subsequ5tly be5 ruptur$ along its c5tre by p[]ful e>?-movem5ts1 ^! *anges all belong$ to ! same p]iod ( dyke-mak+1 & ! subsequ5t uprise ( glassy mat]ial 0 m]ely a lat] phase 9 ! movem5ts ( ! same subt]ranean magma4 ,b :]e1 z probably happ5s 9 ! l>ge majority ( comp\nd dykes1 !re is a /rongly m>k$ diff]5ce betwe5 ! respective b&s ( rock1 we mu/ ei!r inf] t two ess5tially diff]5t magmas co-exi/$ 9 ! volcanic res]voirs und]nea?1 & 7 successively inject$ into ! same fissures1 or t a suffici5t lapse ( "t occurr$ to p]mit a total r5ewal ( ! nature ( ! magma1 & an uprise ( ?is *ang$ mat]ial into fissures :i* sometimes co9cid$ ) old] dykes4 ,if any int]lock+ ( ! cry/als ( ! sev]al b&s ( a comp\nd dyke c\ld be detect$1 we might suppose t ! fir/-inject$ mat]ial _h n become consolidat$ & cold be=e ! uprise ( ! new] rock4 ,b 9 g5]al x w\ld seem t s %>p a l9e ( dem>cation c be drawn betwe5 ! two rocks z to indicate t _! protrusion 0 due to two di/9ct & p]haps widely-sep>at$ volcanic p>oxysms4 ,comp\nd dykes ( basic mat]ial occur n only among ! ord9>y /raight nor?-we/]ly s]ies1 b also among ! less regul> greg>i\s dykes & ve9s1 su* z abundantly int]sect ! gabbro bosses4 ,moreov] !y are to be f\nd among ! y\nge/ intrusions1 = !y trav]se ! masses ( granophyre4 ,conspicu\s examples ( su* late comp\nd dykes are display$ along ! cliffs ( ,/4 ,kilda1 z w be m p>ticul>ly describ$ 9 a lat] ,*apt]4 ,^! ,/4 ,kilda dykes (t5 occupy n v]tical fissures b p>allel r5ts ) a g5tle incl9ation 7see ,figs4 #cfg1 #cfh74 ,! ,t]ti>y volcanic s]ies ( ,scotl& furni%es _m examples ( comp\nd dykes ( a mu* m complex "* :]e p>allel b&s ( "s acid 7granophyre1 felsite1 qu>tz-porphyry7 or int]m$iate 7&esite7 rock is associat$ ) o!rs ( ! m usual basic mat]ial 7dol]ite1 basalt1 diabase74 ,z ! acid intrusions belong to a comp>atively late "p ( ! volcanic hi/ory1 _! modes ( occurr5ce w be discuss$ 9 ,*apt]s xlvi41 xlvii4 & xlviii4 ,b no acc\nt ( ! g5]al sy/em ( dykes w\ld be complete )\t "s ref]5ce to ^! comp\nd examples1 :i* w !re=e be briefly describ$ 9 ! pres5t section ( ?is "w4 ,e>ly 9 ?is c5tury "s /rik+ illu/rations ( ! association ( acid & m basic rocks )9 ! same fissure 7 notic$ by ,jameson 9 ! isl& ( ,arran4 ,he describ$ & figur$ in/ances at ,tormore1 on ! we/ side ( t isl&1 :]e a gr\p ( pit*/ones & basalts or &esites h be5 successively protrud$ into ! same fissures 9 ! 7probably ,p]mian7 r$ s&/ones ( t di/rict4#aii ,footnote #aii3 ,m9]alogy ( ! ,scotti% ,isles1 #ahjj4 ,9 "s in/ances ! m basic rock has be5 fir/ inject$1 & has subsequ5tly be5 disrupt$1 by ! m acid pit*/one4 ,9 o!r cases ! ord] has be5 ! rev]se4 ,! successive ruptures h tak5 place sometimes along ! c5tre1 sometimes at ! m>g9s1 & sometimes irregul>ly along ! bread? ( ! dykes4 ,pr(essor ,judd has rec5tly /udi$ ^! rocks1 & has giv5 descriptions ( _! *emical composition & microscopic *>act]s4 ,he reg>ds !m z hav+ be5 successively inject$ into ! fissures f ! same subt]ranean res]voir1 9 :i* two magmas ( v diff]5t *emical con/itution 7 simultane\sly pres5t4#bjj ,footnote #bjj3 ,qu>t4 ,j\r4 ,geol4 ,soc4 vol4 xlix4 7#ahic71 p4 #ecf4 ,full details ( ! comp\nd dykes ( ,tormore & ,cir ,mhor 9 ,arran1 & ref]5ces to previ\s writ]s w be f\nd 9 ?is pap]4 ,! probable age ( ! y\nge/ eruptive rocks ( ?is isl& w be discuss$ 9 ,*apt] xlvii4 p4 #dah4 ,n[h]e 9 ! ,t]ti>y volcanic regions ( ,brita9 d comp\nd dykes appe> to be s abundant z 9 ! c5tre & s\!rn "p ( ! isl& ( ,skye4 ,dur+ ! progress ( ! ,geological ,survey 9 t di/rict1 ,mr4 ,cl\gh & ,mr4 ,h>k] h mapp$ a l>ge numb] 9 ! gr\nd betwe5 ! ,s\nd ( ,sleat & ! ,r$ ,hills4 ,) reg>d to ^! dykes ,mr4 ,h>k] obs]ves t ! sev]al memb]s are g5]ally petrographically diff]5t1 "s be+ basic1 o!rs int]m$iate1 & o!rs acid4 ,!re is usually1 he rem>ks1 a symmetrical disposition1 two simil> & m basic dykes be+ divid$ by a m acid "o2 = example1 two &esites sep>at$ by a pit*/one4 ,?us at ! m\? ( ! little /ream :i* runs f ,torran into ! bay ea/ f ,dn ,beag a dyke1 app>5tly #ah feet wide1 is f\nd on exam9ation to consi/ ( a c5tral dyke 7specific gravity #bhf7 flank$ by two m basic dykes 7specific gravity #cjb74 ,9 ! great majority ( examples hi!rto obs]v$ 9 ,skye ! two lat]al dykes consi/ ( "s basic rock 7diabase or basalt71 :ile ! c5tral & ?icke/ b& is ( "s acid mat]ial 7granophyre or qu>tz-felsite74 ,?is triple arrangem5t occurs bo? 9 dykes & sills4 ,illu/ration3 ,fig4 #bed4--;,comp\nd dyke1 ,m>ket ,/ance1 ,broad=d1 ,skye4 a1 ,granophyre2 b b1 ,basalt2 c c1 ,torridon s&/one4 ,z an illu/ration ( ! association ( ! two k9ds ( rock 9 dykes ,i may cite an example :i* appe>s on ! s\!rn edge ( ! ,m>ket ,/ance ( ,broad=d 7,fig4 #bed74 ,"h ! *>act]i/ic triple arrangem5t is typically develop$4 ,a c5tral light-col\r$ b&1 ab\t eight to t5 feet broad1 consi/s ( a sph]ulitic granophyre 9 :i* ! sph]ulites are cr[d$ toge!r & project f ! wea!r$ surface l peas1 ?\gh !y d n "h %[ ! curi\s rod-l aggregation s m>k$ 9 "s o!r dykes4 ,on ei!r side ( ?is acid c5tre a n>r[ basalt dyke int]v5es z a wall next to ! ,torridon s&/one :i* "h =ms ! c\ntry-rock4 ,su* comp\nd dykes h sometimes a total wid? ( #ajj feet or m4 ,9 ?is in/ance1 & g5]ally ?r\gh\t ! di/rict1 !re is no?+ to indicate t ! diff]5t b&s ( ! dyke h any relation to ea* o!r z connect$ uprises ( mat]ial f ! same orig9al magma :i* 0 ei!r het]og5e\s or 0 und]go+ a process ( diff]5tiation b5ea? ! t]re/rial cru/4 ,on ! contr>y1 ! sev]al p>ts ( ea* dyke are z di/9ctly m>k$ (f f ea* o!r z !y c\ld h be5 _h !y be5 inject$ at widely sep>at$ int]vals ( volcanic activity4 ,mr4 ,h>k]1 9 ! c\rse ( 8 survey ( ?is ,skye gr\nd1 has obs]v$ t :]e evid5ce is available1 ! c5tral acid dyke is f\nd to be new] ?an ! basic ones4 ,x has n split a s+le basic dyke1 b has ins9uat$ itself betwe5 ! two memb]s ( a d\ble dyke4 ,?is is m cle>ly se5 :5 ! acid magma has be5 =c$ into a triple or multiple basic dyke2 ! p]fect symmetry ( arrangem5t may 9 ?is case be lo/4 ,= in/ance1 on ! %ore nor?-ea/ ( ,corry1 ,broad=d1 a #ac feet dyke ( granophyre occurs 9 a multiple dyke ( basalt1 b x has tak5 its l9e s z to leave only a "o-foot dyke on "o side1 & a gr\p ) a total wid? ( #ab feet on ! o!r4 ,also x has n accurately kept its c\rse1 b has cut obliquely across "o ( ! gr\p ( dykes allud$ to4 ,9 "s cases x is c]ta9 t ! acid magma has to "s ext5t dissolv$ a portion ( ! wall ( a basic dyke ) :i* x has come 9 contact4 ,?is may acc\nt = ! magma f9d+ its easie/ pa? along1 & especially betwe51 pre-exi/+ m basic dykes4 ,?is subject w be aga9 ref]r$ to 9 ,*apt] xlviii41 :5 ! ph5om5a ( comp\nd sills are discuss$4 ,be=e clos+ ?is acc\nt ( comp\nd dykes1 ,i may rem>k t no examples h yet be5 obs]v$ among ! ord9>y ,t]ti>y dykes ( ,brita9 :]e1 by a process ( diff]5tiation betwe5 ! walls ( a fissure1 successive zones h be5 develop$ 9 ! dyke1 diff]+ f ea* o!r 9 /ructure & composition1 b becom+ progressively & ins5sibly m acid t[>ds ! c5tre1 su* z h be5 describ$ f ! old] rocks ( ,norway & ,canada4 ,among ! ,t]ti>y gabbro bosses1 inde$1 !re occur %eets or dykes :i* pres5t a rem>kably b&$ /ructure1 to :i* full ref]5ce w be made 9 lat] pages4 ,b ,i h nev] se5 any?+ at all resembl+ su* a /ructure among ! dykes ( &esite1 dol]ite1 or basalt4 #ag4 ,,contact-,,metamorphism ,,( ,,! ,,dykes ,a geologi/ might naturally expect t su* abundant intrusions ( igne\s rock z ^? ( ! dykes %\ld be accompani$ ) pl5tiful pro(s ( contact-metamorphism4 ,b 9 actual fact1 evid5ce ( any s]i\s am\nt ( alt]ation is s+ul>ly sc>ce4 ,a slight induration ( ! rocks on ei!r side ( a dyke is g5]ally all ! *ange t c be detect$4 ,illu/ration3 ,fig4 #bee4--,section ( coal r5d]$ column> by intrusive basalt1 %ore1 ,saltcoats1 ,ayr%ire4 a1 ,fireclay2 b1 ,coal r5d]$ prismatic ne> ! basalt2 c1 ,d>k %ale2 d1 ,basalt-rock4 ,"s ( ! l>g] dykes1 h[ev]1 %[ m m>k$ metamorphism1 ! nature ( :i* appe>s 9 _m cases to be *iefly det]m9$ by ! *emical composition ( ! rock affect$4 ,?us a consid]able alt]ation has be5 sup]9duc$ on c>bonace\s /rata1 p>ticul>ly on seams ( coal4 ,9 ! ,ayr%ire coal-field ! alt]ation ( ! coal ext5ds sometimes #aej feet f ! dyke1 ! ext5t ( ! *ange dep5d+ n m]ely on ! mass ( ! igne\s rock1 b on ! nature ( ! coal1 & possibly on o!r causes4 ,close to a dyke1 coal passes into a k9d ( soot or c9d]1 sometimes assumes ! =m ( a f9ely column> coke 7,fig4 #bee71 & occasionally has become vesicul> aft] be+ fus$4#bja ,%ales are conv]t$ into a h>d fl9ty sub/ance t breaks ) a con*oidal fracture & r+s "u ! hamm]4 ,fireclay is bak$ into a porcela9-l mat]ial4 ,lime/one is *ang$ = a few in*es into m>ble4 ,z an illu/ration ( ?is alt]ation1 ,i may cite a dyke t5 feet broad :i* cuts ?r\gh ! *alk 9 ! ,templepatrick ,qu>ry1 ,antrim4 ,= ab\t six in*es f ! igne\s rock ! *alk has pass$ into a f9ely sac*>oid condition1 & its organisms are effac$4 ,b beyond t di/ance ! cry/all9e /ructure rapidly dies away1 ! micro-organisms beg9 to make _! appe>ance1 & )9 a space ( "o foot f ! dyke ! *alk assumes its ord9>y "*4 ,footnote #bja3 ,explanation ( ,%eet #bb1 ,geological ,survey ( ,scotl&1 p4 #bf4 ,s&/ones are indurat$ by dykes into a k9d ( qu>tzite1 sometimes assume a column> /ructure 7! columns be+ direct$ away f ! dyke-walls71 & = sev]al feet or y>ds h _! yell[ or r$ col\rs blea*$ out ( !m4 ,! granite ( ,b5 ,crua*an :]e qu>ri$ on ,lo* ,awe1 z ,i am in=m$ by ,mr4 ,j4 ,s4 ,grant ,wilson1 is trav]s$ by a basic dyke1 & = a di/ance ( ab\t #bj feet is r5d]$ d>k] 9 col\r1 becomes granul>1 & _c be poli%$ & made saleable4 ,:]e _m dykes h be5 cr[d$ toge!r1 _! collective effects 9 ! alt]ation ( ! /rata trav]s$ by !m h sometimes be5 /rongly develop$4 ,"o ( ! mo/ rem>kable illu/rations ( ?is influ5ce is pres5t$ by ! di/rict ( ,/ra?aird1 :i* 0 cit$ by ,maccullo* = ! abundance ( its dykes4 ,9 rec5tly mapp+ ?is gr\nd = ! ,geological ,survey1 ,mr4 ,h>k] has obs]v$ 9 "s places a score or m dykes 9 actual juxtaposition1 :ile ov] consid]able di/ances he f\nd x difficult to detect any trace ( ! ,jurassic /rata1 ?r\gh :i* ! igne\s rocks h asc5d$4 ,z might be expect$ "u ^! circum/ances1 su* portions ( ! /rata z c be se5 display an altoge!r exceptional am\nt ( contact-metamorphism4 ,mr4 ,h>k] has notic$ "s lime/ones at ,camasun>y :i* h be5 *ang$ into v rem>kable lime-silicate rocks1 ) s+ul> bun*es ( diopside cry/als4 ,^!1 h[ev]1 are ! extremes ( contact-metamorphism by ! ,t]ti>y basic dykes4 ,a geologi/ visit+ ! ,liassic %ores ( ,/ra? 9 ,skye w n fail to be surpris$ at ! v slight degree ( alt]ation 9 circum/ances :]e he w\ld h expect$ to f9d x /rongly pron\nc$4 ,! d>k %ales1 ?\gh ribb$ across ) dykes1 are sometimes h>dly ev5 h>d5$1 & at ! mo/ are only indurat$ f an in* or two to ab\t two feet4 ,^! bak$ b&s project above ! re/ ( ! m easily d5ud$ %ales1 & s adh]e to ! dykes z almo/ to seem "p ( !m4 ,aga9 ! lime/ones1 :]e trav]s$ by dykes "s di/ance ap>t1 are n r5d]$ 9 any appreciable degree m cry/all9e ev5 up to ! v m>g9 ( ! intrusive rock4 ,:]e ! igne\s mat]ial has be5 ?ru/ betwe5 ! /rata 9 sills1 x has produc$ f> m g5]al & s]i\s metamorphism ?an :5 x occurs 9 ! =m ( s+le dykes4 ,! fam\s rock ( ,portru%1 already ref]r$ to z hav+ be5 once gravely cit$ z an example ( fossilif]\s basalt1 is a good illu/ration ( ! way 9 :i* ,lias %ale is porcellaniz$ :5 ! intrud$ igne\s mat]ial has be5 ?ru/ betwe5 ! planes ( b$d+4 ,9 ! ,we/ ( ,scotl&1 :]e dykes are s abundantly develop$1 consid]able diff]5ces c be obs]v$ betwe5 ! am\nt ( metamorphism sup]9duc$ by adjac5t dykes :i* may be ( ! same ?ickness1 & cut ?r\gh ! same k9d ( /rata4 ,su* v>iations h n probably aris5 f diff]5ces 9 ! temp]ature ( ! orig9al molt5 rock4 ,p]haps !y are r to be assign$ to ! l5g? ( "t occupi$ by ! asc5t ( ! lava 9 ! fissure4 ,if1 = in/ance1 ! fissure op5$ to ! surface & dis*>g$ lava !re1 ! rocks ( its walls w\ld be expos$ to a cont9u\s /ream ( molt5 rock z long z ! outfl[ la/$4 ,!y w\ld ?us h _! temp]ature m highly rais$1 & ma9ta9$ at su* an elevation = a long] "t ?an :]e ! magma1 at once arre/$ )9 ! fissure1 imm$iately proce$$ to cool & consolidate !re4 ,x w\ld be an int]e/+ & important conclusion if we c\ld1 f ! nature or am\nt ( _! contact-metamorphism1 di/+ui% ^? dykes :i* = "s "t s]v$ z *annels = ! dis*>ge ( lava above gr\nd4 ,"s dykes :i* h caught up fragm5ts ( old] rocks 9 _! asc5t h ex]cis$ a consid]able solv5t action on ^! inclusions4 ,examples ( ?is feature h already be5 cit$ f ,skye1 :]e !y h be5 /udi$ by ,mr4 ,h>k] 7pp4 #abi1 #afc74 ,9 connection ) ! metamorphism sup]9duc$ by dykes1 ref]5ce may aga9 be made to ! alt]ation :i* !y !mselves und]go :]e !y h invad$ a c>bonace\s %ale or coal4 ,! igne\s rock1 z we h se51 loses its d>k col\r & obvi\sly cry/all9e /ructure1 & becomes a pale yell[ or :ite1 dull1 e>?y sub/ance1 or :ite trap4 ,! *emical *anges involv$ 9 ?is alt]ation h be5 describ$ by ,sir ,j4 ,l[?ian ,bell4#bjb ,dr4 ,/e*] has also discuss$ ! alt]ations traceable by ! aid ( ! microscope4#bjc ,?\gh mo/ ( ! in/ances ( su* trans=mation 9 ,brita9 occur 9 ! ,c>bonif]\s sy/em1 & h tak5 place 9 intrusive rocks ( probably1 = ! mo/ "p1 ,c>bonif]\s or ,p]mian age1 yet !y are n unkn[n 9 ! ,t]ti>y volcanic s]ies4 ,"s ( ! :ite trap ( ! ,coal-measures may inde$ belong to ! ,t]ti>y p]iod1 b ! coals & c>bonace\s %ales int]/ratifi$ 9 ! ,t]ti>y basalt-plateaux h react$ on bo? ! sup]ficial lavas & ! sills1 & h giv5 rise to ! same k9d ( alt]ation z 9 ! ,c>bonif]\s sy/em1 z w be %[n 9 a lat] ,*apt]4 ,footnote #bjb3 ,proc4 ,roy4 ,soc4 xxiii4 7#ahge71 p4 #edc4 ,footnote #bjc3 ,ts*]mak's ,m9]alogis*e ,mit!ilung51 ix4 7#ahhg71 p4 #ade1 & ,proc4 ,roy4 ,soc4 ,ed94 #ahhh4 ,illu/ration3 ,fig4 #bef4--;,dol]ite dyke ) m>g9al b&s ( :ite trap1 9 black %ale1 ,l[] ,lias1 ,pabba4 a1 ,black c>bonace\s ,l[] ,lias ,%ale2 b b1 b&s ( indurat$ %ale f #ae in*es to #b feet broad2 c1 dol]ite dyke #c feet #c in*es broad2 d d1 b&s ( alt]$ dol]ite or :ite trap1 #c to #e in*es broad4 ,"s m>k$ examples ( ?is alt]ation ( intrusive igne\s mat]ial are to be obs]v$ among ! basalt dykes :i* cut ! ,l[] ,lias ,%ales ( ,skye4 ,^! %ales1 :]e black & c>bonace\s1 z 9 ! isl& ( ,pabba1 h ex]cis$ an unmi/akable influ5ce on ! abundant dykes :i* int]sect !m4 ,! *ill$ selvage ( ea* dyke has assum$ ! dull e>?y pale-grey or yell[i% aspect1 :i* ext5ds = a few in*es f ! wall into ! int]ior1 :]e x rapidly passes into ! ord9>y black cry/all9e basalt4 ,^! features w be readily und]/ood f ! accompany+ diagram 7,fig4 #bef74 ,:]e ! dykes give (f n>r[ ve9s a few in*es broad1 ^! consi/ entirely ( ! :ite trap4 ,! %ales are (t5 trav]s$ ) /rong jo9ts p>allel to ! walls ( ! dykes1 & ! transv]se jo9ts ( ! dykes are sometimes prolong$ into ! b&s ( indurat$ %ale4 #ah4 ,,relation ,,( ,,dykes ,,to ,,! ,,geological ,,/ructure ,,( ,,! ,,di/ricts ,,:i* ,,!y ,,trav]se4 ,9 no respect d ! ,t]ti>y dykes ( ,brita9 /& m di/+ui%$ f all ! o!r rocks ( ! c\ntry ?an 9 _! extraord9>y indep5d5ce ( geological /ructure4 ,! successive gr\ps ( ,palozoic & ,mesozoic /rata h be5 s tilt$ z to foll[ ea* o!r 9 approximately p>allel b&s1 :i* run obliquely across ! isl& f s\?-we/ to nor?-ea/4 ,! mo/ important l9es ( fault take ! same g5]al l9e4 ,! contemporane\sly includ$ igne\s rocks foll[1 ( c\rse1 ! tr5d ( ! /ratifi$ deposits among :i* !y lie1 & ev5 ! intrusive sills gr\p !mselves along ! g5]al /rike ( ! :ole c\ntry4 ,b ! ,t]ti>y dykes h _! own indep5d5t direction1 to :i* !y adh]e amid ! extreme/ div]sities ( geological arrangem5t4 ,9 ! fir/ place1 ! dykes int]sect ne>ly ! :ole range ( ! geological =mations ( ! ,briti% ,isl&s4 ,9 ! ,out] ,hebrides & nor?-we/ ,highl&s1 !y rise ?r\gh ! mo/ anci5t 7,lewisian7 gneisses1 ?r\gh ! r$ pre-,cambrian 7,torridon7 s&/ones1 & ?r\gh ! olde/ memb]s ( ! ,cambrian sy/em4 ,9 ! s\!rn ,highl&s1 !y pursue _! c\rse across ! gn>l$ & twi/$ s*i/s ( ! y\ng] cry/all9e 7,dalradian7 s]ies4 ,9 ! ,s\? ( ,scotl& & ,nor? ( ,engl&1 !y trav]se ! v>i\s subdivisions ( ! ,l[] & ,upp] ,silurian rocks4 ,9 ! bas9s ( ! ,tay1 ,=?1 & ,clyde !y cross ! pla9s & ridges ( ! ,old ,r$ ,s&/one1 ) its deep pile ( int]calat$ volcanic mat]ial4 ,9 ,c5tral ,scotl&1 & ! nor!rn ,engli% c\nties1 !y occur abundantly 9 ! ,c>bonif]\s sy/em1 & h de/roy$ ! seams ( coal4 ,9 ,cumb]l& & ,durham1 !y trav]se ! ,p]mian & ,trias gr\ps4 ,9 ,york%ire1 & along ! ,we/ ( ,scotl&1 !y are f\nd runn+ ?r\gh ,jurassic /rata4 ,9 ,antrim1 !y int]sect ! ,*alk4 ,bo? 9 ! ,nor? ( ,irel&1 & all ?r\gh ! *a9 ( ! ,inn] ,hebrides1 !y ab\nd 9 ! great %eets & bosses ( ,t]ti>y volcanic rocks4 ,^! are ! y\nge/ =mations ?r\gh :i* !y rise4 ,b x is des]v+ ( note1 t !y int]sect e great gr\p ( ^! ,t]ti>y volcanic products1 s t !y include 9 _! numb] ! late/ kn[n manife/ations ( eruptive action 9 ! geological hi/ory ( ,brita94#bjd ,footnote #bjd3 ,!y h n be5 f\nd cutt+ ! pit*/one-lava ( ! ,scuir ( ,eigg4 ,9 ! second place1 9 rang+ across gr\ps ( rock belong+ to su* widely div]se p]iods1 ! dykes mu/ necess>ily (t5 pass abruptly f "o k9d ( mat]ial & geological /ructure to ano!r4 ,b1 z a rule1 !y d s )\t any s5sible deviation f _! usual tr5d1 or any alt]ation ( _! av]age wid?4 ,"h & !re1 inde$1 we may obs]ve a dyke to foll[ a m wavy or m rapidly s9u\s or zig-zag c\rse 9 "o gr\p ( rocks ?an 9 ano!r4 ,yet1 s f> z ,i h myself be5 able to obs]ve1 su* s9uosities may occur 9 almo/ any k9d ( mat]ial1 & are n satisfactorily explicable by any diff]5ce ( texture or arrangem5t 9 ! rocks at ! surface4 ,no dyke trav]ses a great] v>iety ( s$im5t>y =mations ?an t ( ,clevel&4 ,9 ! ea/]n "p ( its c\rse1 x rises ?r\gh all ! ,mesozoic gr\ps up to ! ,cornbra%4 ,fur!r we/ x cuts across ea* ( ! diff]5t subdivisions ( ! ,c>bonif]\s sy/em2 &1 ( c\rse1 x mu/ trav]se all ! old] =mations :i* und]lie ^!4 ,b ! occasional rapid *anges noticeable 9 its wid? & direction d n seem to be ref]able to any correspond+ /ructure 9 ! surr\nd+ rocks4 ,! ,*eviot dyke crosses f ! ,c>bonif]\s area ( ,nor?umb]l& into ! ,upp] ,silurian rocks & ,l[] ,old ,r$ ,s&/one volcanic tract ( ! ,*eviot ,hills4 ,x !n /rikes across ! ,upp] ,old ,r$ ,s&/one ( ,roxburgh%ire1 & /ill ma9ta9+ ! same p]si/5t tr5d1 sweeps we/w>d into ! int5sely plicat$ ,silurian rocks ( ! ,s\!rn ,upl&s4 ,its occasional deviations h no obvi\s ref]5ce to any visible *ange ( /ructure 9 ! adjac5t =mations4 ,aga91 "s ( ! great dykes at ! head ( ,clydesdale furni% /rik+ illu/rations ( entire indiff]5ce to ! nature ( ! rock ?r\gh :i* !y run4 ,quitt+ ! ,silurian upl&s1 !y keep _! l9e across ,old ,r$ ,s&/one & ,c>bonif]\s rocks1 & ?r\gh l>ge masses ( eruptive mat]ial4 ,9 ! ?ird place1 n only are ! dykes n deflect$ by great div]sities 9 ! li?ological "* ( ! rocks :i* !y trav]se1 !y ev5 cross )\t deviation "s ( ! mo/ important geological features 9 ! g5]al framework ( ! c\ntry4 ,"s ( ! ,scotti% examples are s+ul>ly impressive 9 ?is respect4 ,^? :i* /rike nor?-we/w>d f ! upl&s ( ,clydesdale cross )\t deflection ! great b\nd>y-fault :i*1 by a ?r[ ( sev]al ?\s& feet1 br+s ! ,l[] ,old ,r$ ,s&/one aga9/ ,silurian rocks4 ,!y trav]se "s l>ge faults 9 ! valley ( ! ,d\glas coal-field1 pass completely across ! axis ( ! ,haugh%aw ,hills1 :]e ! ,upp] ,silurian rocks are once m br\ght up to ! surface1 & also ! long felsite ridge ( ,prie/hill4 ,! dykes 9 ! c5tre ( ! k+dom ma9ta9 _! l9e across "s ( ! l>ge masses ( igne\s rock t protrude ?r\gh ! ,c>bonif]\s sy/em4 ,fur!r nor?1 ! dykes ( ,p]?%ire cut across ! great %eets ( volcanic mat]ial t =m ! ,o*il ,hills1 z well z ?r\gh ! piles ( s&/one & conglom]ate ( ! ,l[] ,old ,r$ ,s&/one1 & !n g "r across ! b\nd>y-fault ( ! ,highl&s1 to pursue _! way 9 ! same indep5d5t mann] ?r\gh grit1 qu>tzite1 or mica-s*i/1 & across gl5 & lake1 moor & m\nta94 ,no "o c contemplate ^! repeat$ examples ( an entire want ( connection betwe5 ! dykes & ! nature & arrangem5t ( ! rocks :i* !y trav]se )\t be+ conv9c$ t ! l9es ( r5t up :i* ! mat]ial ( ! dykes rose 7 n1 z a rule1 old fractures 9 ! e>?'s cru/1 b 7 fre% fissures1 op5$ across ! c\rse ( ! old] dislocations & /rike ( ! c\ntry by ! same s]ies ( subt]ranean op]ations to :i* ! uprise ( ! molt5 mat]ial ( ! dykes 0 also due4 ,9 ! f\r? place1 ! dykes = ! mo/ "p are n co9cid5t ) visible l9es ( fault4 ,aft] ! exam9ation ( hundr$s ( dykes 9 all p>ts ( ! c\ntry1 & ) all ! help :i* b>e hillsides & well-expos$ coa/-sections c af=d1 ! numb] ( in/ances :i* h be5 met ) :]e dykes h avail$ !mselves ( l9es ( fault is surpris+ly small4 ,"s ( ^! cases w be imm$iately cit$4 ,to :atev] cause we may ascribe ! rupture ( ! solid cru/ ( ! e>?1 :i* admitt$ ! rise ( molt5 rock to =m ! dykes1 !re c be no d\bt t x 0 n g5]ally att5d$ ) t displacem5t ( level on "o or bo? sides ( ! dislocation1 :i* we associate ) ! idea ( a fault4 ,n[h]e c ?is important "p ( dyke-/ructure be m cle>ly illu/rat$ ?an along ! ,clevel& dyke1 :]e ! igne\s rock rises ?r\gh almo/ horizontal ,jurassic /rata & g5tly incl9$ ,coal-measures 7,figs4 #bda1 #bdb1 #bdc1 #bdd74 ,besides ! localities already cit$1 m9+ op]ations bo? = coal & = ! ,liassic iron/one h prov$ ov] a wide area t ! dyke has n ris5 along a l9e ( fault4 ,aga91 9 ,skye1 ,raasay1 ,eigg1 & o!r p>ts ( ! we/ coa/1 :]e ,jurassic /rata & ! horizontal basalts ( ! plateaux are pl5tifully cut ?r\gh by dykes1 ! same b$s may g5]ally be se5 at ! same level on ei!r side ( !m4 ,9 ! fif? place1 :ile complete indiff]5ce to geological /ructure is ! g5]al rule among ! dykes1 in/ances d occur 9 :i* ! molt5 mat]ial has f\nd its way upw>d along old l9es ( rupture4 ,mo/ ( su* in/ances are to be f\nd 9 di/ricts :]e previ\sly exi/+ faults happ5$ to run 9 ! same g5]al direction z t foll[$ by ! dykes4 ,^! l9es ( fracture might naturally be re-op5$ by any great e>?-movem5ts act+ 9 _! direction1 & w\ld af=d ready *annels = ! asc5t ( ! lava1 z we h se5 to h n infrequ5tly happ5$ 9 ! case ( dyke-fissures1 :i* are %[n by comp\nd dykes to h sometimes be5 re-op5$ sev]al times 9 succession ev5 aft] hav+ be5 fill$ up ) basalt4 ,yet x is curi\s t1 ev5 :5 _! tr5d w\ld h suit$ ! l9e ( ! dykes1 faults h n be5 m l>gely made use ( = ! purpose ( relief4 ,"s ( ! be/ examples ( ! co9cid5ce ( dykes ) pre-exi/+ faults 9 ! same direction are to be f\nd 9 ! ,/irl+%ire coal-field4 ,! dyke t runs f ,torphi*5 = #bc miles to ,cadd] occupies a l9e ( fault :i* at ,slamannan has a d[n-?r[ ( m ?an #gj fa?oms4 ,! next dyke fur!r s\? has also ris5 along an ea/ & we/ fault4 ,b o!r examples may be obs]v$ :]e pre-exi/+ fissures h s]v$ to deflect dykes f _! usual l9e ( tr5d4 ,?us ! ,clevel& dyke1 aft] cross+ sev]al faults 9 ! ,coal-measures1 at la/ enc\nt]s "o ne> ,cockfield ,fell1 :i* lies obliquely across its pa?4 ,in/ead ( cross+ ?is fault x b5ds %>ply r\nd a few po9ts s\? ( we/1 & aft] keep+ along ! s\!rn flank ( ! fault = ab\t a mile1 s9ks out ( rea*4 ,"s ( ! ,scotti% examples are m rem>kable4 ,"o ( ! be/ ( !m occurs 9 ! ,sanquh> coal-field1 :]e a dyke runs = two miles & a half along ! l>ge fault t "h br+s d[n ! ,coal-measures aga9/ ! ,l[] ,silurian rocks4 ,at ! nor?-we/]n end ( ! bas91 ?is fault makes an abrupt b5d ( #fj to ,w4,s4,w41 & ! dyke turns r\nd ) x1 keep+ ?is alt]$ c\rse = a mile & a half1 :5 x /rikes away f ! fault1 crosses a n>r[ belt ( ,l[] ,silurian rocks1 & f9ds its way into ! p>allel b\nd>y fault :i* def9es ! nor?-we/]n m>g9 ( ! ,s\!rn ,upl&s4 ,illu/ration3 ,fig4 #beg4--,map ( ! *ief dykes betwe5 ,lo*s ,riddon & ,/riv5 7,c4 ,t4 ,cl\gh1 ,geological ,survey1 ,%eet #bi74 ,! l>ge ,e4 & ,w4 dyke is a cont9uation ( t :i* rea*es ! %ore ( ! ,fir? ( ,clyde at ,dunoon4 ,"s ( ! ,p]?%ire dykes1 :]e !y rea* ! great b\nd>y-fault ( ! ,highl&s1 pres5t specially int]e/+ features4 ,!re c be no d\bt t ?is dislocation is "o ( ! mo/ important 9 ! g5]al framework ( ! ,briti% ,isles1 ?\gh no def9ite e/imate has yet be5 =m$ ( h[ mu* rock has be5 actually displac$ by x4 ,! fact t 9 "o place ! b$s ( ,old ,r$ ,s&/one are ?r[n on end = "s two miles back f x1 %[s t x mu/ be a v p[]ful fracture4 ,"h1 !re=e1 if any:]e1 ei!r an entire cessation ( ! dykes1 or at lea/ a complete deflection ( _! c\rse might be anticipat$4 ,x w\ld require1 we might suppose1 a s+ul>ly pot5t dislocation to op5 a way = ! asc5t ( ! lava ?r\gh su* cru%$ & compress$ rocks1 & /ill m to prolong ! g5]al l9e ( a fracture across ! old fault4 ,two great dykes1 ab\t half a mile ap>t1 run 9 a direction a little s\? ( we/ across ! pla9 ( ,/ra!>n4 ,pass+ to ! s\? ( ! village ( ,crieff1 !y hold on _! way until !y rea* ! highly-incl9$ b$s ( s&/one & conglom]ate :i* "h lean aga9/ ! ,highl& fault 9 ,gl5 ,artney4 ,!y !n turn r\nd t[>ds s\?-we/1 & run up ! gl5 along ! /rike ( ! b$s1 keep+ approximately p>allel to ! fault = ab\t ?ree miles1 :5 !y bo? /rike across ! fault1 & pursue a ,w4,s4,w4 l9e ?r\gh ! contort$ cry/all9e rocks ( ! ,highl&s4 ,ab\t two miles fur!r s\?1 ano!r dyke cont9ues its normal c\rse across ! belt ( upturn$ ,old ,r$ ,s&/one2 b :5 x rea*es ! fault x b5ds r\nd & foll[s ! l9e ( dislocation1 sometimes co9cid+ )1 sometimes cross+ or runn+ p>allel ) t l9e1 at a %ort di/ance 7see ,fig4 #bdg74 ,"s rem>kable examples h be5 mapp$ by ,mr4 ,cl\gh 9 ,ea/]n ,argyle%ire1 :]e broad b&s ( basalt or o!r alli$ rock run 9 a ,n4 & ,s4 direction1 & are =m$ by ! conflu5ce ( ,n4,w & ,s4,e4 or ,n4,n4,w4 & ,s4,s4,e4 dykes1 :]e ^! are drawn into a l9e ( fault 7,fig4 #beg74 ,^! broad b&s1 he has f\nd to be n usually traceable = m ?an a mile or s1 = ! dykes ( :i* !y are made up w n be div]t$ f _! regul> pa?s = m ?an a c]ta9 di/ance1 s t "o by "o ! dykes leave ! comp\nd b& to pursue _! normal c\rse4 ,he has obs]v$ t ! occasional great ?ickness ( ^! comp\nd b&s dep5ds p>tly on ! size & p>tly on ! numb] ( sep>ate dykes t are div]t$ into ! l9e ( transv]se fissure2 =1 :]e ! fissure crosses an area ) few] nor?-we/ dykes1 ! b& becomes ?9n] or ceases altoge!r4 ,9 "s r>e cases1 ! dykes h be5 %ift$ by m rec5t faults4 ,i %all h occasion to %[ t faults ( m ?an #ajjj feet h tak5 place s9ce ! ,t]ti>y basalt-plateaux 7 =m$4 ,!re is !re=e no reason :y "h & !re a fault ) a l[ hade %\ld n h %ift$ ! outcrop ( a dyke4 ,b ! fact rema9s1 t1 z a g5]al rule1 ! dykes run indep5d5tly ( faults ev5 :]e !y approa* close to !m4 ,mr4 ,cl\gh has obs]v$ "s int]e/+ cases 9 ,s\?-ea/]n ,argyle%ire1 :]e ! app>5t %ift+ ( a dyke by faults proves to be deceptive1 & :]e ! dyke has = %ort di/ances m]ely avail$ itself ( old l9es ( fracture4 ,"o ( ! mo/ rem>kable ( ^! is pres5t$ by ! l>ge dyke :i* runs we/w>d f ,dunoon4 ,no few] ?an ?ree times1 9 ! c\rse ( f\r miles betwe5 ,lo*s ,/riv5 & ,riddon1 does ?is dyke make %>p *anges ( tr5d ne>ly at "r angles to its usual direction1 :]e x enc\nt]s nor? & s\? faults 7,fig4 #beg74 ,x w\ld be natural to conclude t ^! *anges are actual dislocations due to ! faults4 ,b ! c>eful obs]v] j cit$ has be5 able to trace ! dyke 9 a v att5uat$ & uncru%$ =m along "s ( ^! cross faults1 & ?us to prove t ! faults are ( old] date1 b t !y h modifi$ ! l9e ( ! long ea/ & we/ fissure up :i* ! mat]ial ( ! dyke asc5d$4 #ai4 ,,data ,,= ,,e/imat+ ,,! ,,geological ,,age ,,( ,,! ,,dykes ,i h already assign$ reasons = reg>d+ ! sy/em ( nor?-we/ & s\?-ea/ or ea/ & we/ dykes z belong+ to ! ,t]ti>y volcanic p]iod 9 ! geographical hi/ory ( ! ,briti% ,isl&s4 ,b ,i h no evid5ce t !y 7 re/rict$ to any "p ( t p]iod4 ,on ! contr>y1 !re is e reason to consid] ! uprise ( ! e>lie/ & late/ dykes to h be5 sep>at$ by a protract$ int]val4 ,t !y d n all belong to "o epo* has be5 already indicat$1 & may n[ be m specially prov$4 ,! int]section ( "o dyke by ano!r furni%es an obvi\s crit]ion ( relative age4 ,maccullo* drew att5tion to ?is te/1 & /at$ t x _h enabl$ him to make out two di/9ct sets ( dykes 9 ,skye & ,rum4 ,b he confess$ t x fail$ to af=d any in=mation z to ! l5g? ( ! int]val ( "t betwe5 !m4#bje ,x is n always s easy z might be ?\ght to make sure :i* ( two int]sect+ dykes is ! old]4 ,z 0 expla9$ 9 ,*apt] vi4 7vol4 i4 p4 #ha71 we h to look = ! f9]-gra9$ m>g9al /rip at ! edge ( a dyke1 :i*1 :]e traceable across ano!r dyke1 m>ks at once _! relative age4 ,! cross jo9ts ( ! two dykes also run 9 diff]5t directions4 ,ref]5ce may aga9 be made to ! illu/ration giv5 9 ,fig4 #bec :]e ?ree di/9ct gr\ps ( dykes int]sect ea* o!r z !y trav]se ! ,lias lime/ones ( ,skye4 ,! *ill$ edges & ! diff]5t arrangem5t ( jo9ts m>k ^! dykes out f ea* o!r1 :ile ! ord] 9 :i* !y cross ea* o!r furni%es a clue to _! relative age4 ,if f su* sections1 repeat$ 9 diff]5t p>ts ( a di/rict1 c]ta9 p]si/5t petrographical *>act]s c be asc]ta9$ to di/+ui% ea* p>ticul> sy/em ( dykes1 a guide may !reby be obta9$ = ! *ronological gr\p+ ( ! intrusions ev5 :]e evid5ce ( actual int]section is n visible4 ,9 ! case j cit$ f ,skye1 ! lat] nor? & s\? dykes are *>act]iz$ by _! l9es ( vesicul> cavities & by ! l>ge porphyritic felsp>s :i* !y conta94 ,footnote #bje3 ,trans4 ,geol4 ,soc4 iii4 p4 #ge4 ,x is obvi\s1 h[ev]1 t al?\gh sections ( ?is k9d suffice to prove ! dykes to belong to di/9ct p]iods ( intrusion1 no long] int]val ne$ h elaps$ betwe5 _! successive production ?an 0 requir$ = ! solidification & assumption ( a jo9t-/ructure by an old] dyke be=e a y\ng] broke ?r\gh x4 ,!y may bo? belong to "o brief p]iod ( volcanic activity4 ,b :5 we pass to a s]ies ( dykes trav]s+ a consid]able di/rict ( c\ntry1 & f9d t ^? :i* run 9 "o direction are inv>iably cut by ^? :i* run 9 ano!r1 ! inf]5ce c h>dly be resi/$ t !y d n belong to ! same p]iod ( eruption1 b m>k successive epo*s ( volcanic en]gy4 ,an excell5t example ( ?is k9d ( evid5ce is furni%$ by ,mr4 ,cl\gh f ,ea/]n ,argyle%ire4 ,! ea/ & we/ dykes 9 t di/rict are und\bt$ly old] ?an ^? :i* run 9 a ,n4,n4,w4 direction 7,fig4 #beg74bjf ,! latt] are by f> ! mo/ abundant1 & are on ! :ole mu* n>r[]1 less p]si/5t1 & f9] 9 gra94 ,on ! opposite coa/ ( ! ,clyde1 a simil> d\ble set ( dykes may be trac$ ?r\gh ,r5frew%ire1 ^? 9 an ea/ & we/ direction be+ comp>atively few1 :ile ! y\ng] ,n4,n4,w4 s]ies is well develop$4 ,! great %eets or sills connect$ ) "o ( ! ,/irl+%ire dykes1 already describ$1 appe> to me to furni% simil> evid5ce 9 ! y\ng] dykes :i* run ?r\gh !m4 ,& ?is evid5ce is peculi>ly valuable1 = x %[s a succession ev5 among adjac5t dykes :i* all run 9 ! same g5]al direction4 ,footnote #bjf3 ,z already /at$1 ,mr4 ,cl\gh & also ,mr4 ,gunn are incl9$ to sep>ate ^! old] ea/ & we/ dykes f ! ,t]ti>y s]ies & to reg>d !m z probably ( late ,palozoic age4 ,b 9 all ^! cases x is obvi\s t we h little indication ( ! l5g? ( "t t int]v5$ betwe5 ! successive injections ( ! dykes4 ,9 ,skye1 h[ev]1 m def9ite evid5ce pres5ts itself t ! int]val mu/ h be5 9 "s cases a protract$ "o4 ,z f> back z ! ye> #aheg1bjg ,i %[$ t ! basic dykes ( ,/ra? 9 ,skye are ( two ages2 t "o set 0 erupt$ be=e ! appe>ance ( ! sy5ite 7granophyre7 ( t di/rict1 & 0 cut (f by ! latt] rock2 & t ! o!r arose aft] ! sy5ite :i* x int]sect$4 ,rec5t re-exam9ation has enabl$ me to confirm & ext5d ?is obs]vation4 ,! y\ng] s]ies :i* trav]ses ! granophyre is mu* less num]\s ?an ! old] s]ies 9 ! same di/ricts4 ,9 ,*apt] xlvi41 :]e ! relations ( ! granophyres to o!r memb]s ( ! volcanic s]ies w be discuss$1 fur!r details w be giv5 f t region ( ,skye to demon/rate t !re is a pre-granophyre & a po/-granophyre s]ies ( basic dykes4 ,z a good illu/ration ( ! y\ng] s]ies ,i may ref] to ! way 9 :i* ^! rocks make _! appe>ance 9 ! isl& gr\p ( ,/4 ,kilda1 :]e bo? ! gabbros & granophyres ( ! ,t]ti>y volcanic s]ies are *>act]i/ically develop$4 ,num]\s dykes trav]se bo? ^! rocks4 ,^? 9 ! gabbro are m abundant ?an ^? 9 ! granophyre--a circum/ance :i* is exactly p>allel$ among ! basic & acid bosses ( ,skye4 ,x is n improbable t 9 ^! remote isl&s a simil> diff]5ce 9 age & 9 petrographical "* may be made out betwe5 two s]ies ( dykes1 "o old] & ! o!r y\ng] ?an ! granophyre4 ,!re is ample pro(1 at all ev5ts1 ( a po/-granophyre s]ies4 ,footnote #bjg3 ,qu>t4 ,j\r4 ,geol4 ,soc4 vol4 xiv4 p4 #af4 ,illu/ration3 ,fig4 #beh4--;,basalt-ve9s trav]s+ granophyre1 ,/4 ,kilda4 ,! pale col\r ( ! precipices 9 :i* ! ,/4 ,kilda granophyre plunges into ! sea gives special prom95ce to ! d>k ribbon-l /reaks :i* m>k ! c\rse ( basalt-dykes ?r\gh t rock4 ,moreov] ! great] liability ( ! mat]ial ( ! dykes to decay causes !m to wea!r into long l9es ( not* or recess4 ,f\r or five su* dykes foll[ ea* o!r 9 ne>ly p>allel b&s1 :i* slant upw>d f ! sea-level on ! ea/]n face ( ! hill ,cona*] to a height ( sev]al hundr$ feet4#bjh 7,fig4 #beh1 see also ,fig4 #cfg47 ,footnote #bjh3 ,?is relation ( ! lat] dykes to ! granophyre 0 obs]v$ "h by ,maccullo* 7,we/]n ,isles1 vol4 ii4 p4 #ee74 ,! acid eruptions ( ! ,inn] ,hebrides are m>k$ by s v>i$ a s]ies ( rocks1 & s complex a geological /ructure1 t !y may1 ) "s confid5ce1 be reg>d$ z hav+ occupi$ a consid]able int]val ( geological "t4 ,yet we f9d t ?is prolong$ episode 9 ! volcanic hi/ory 0 bo? prec$$ & foll[$ by ! extravasation ( basic dykes4 ,ref]5ce has already be5 made to rec5t obs]vations by ,mr4 ,h>k]1 :o1 9 mapp+ ! ,/ra? di/rict ( ,skye = ! ,geological ,survey1 has n only confirm$ ! g5]alization z to ! exi/5ce ( a s]ies ( dykes e>li]1 & ano!r lat]1 ?an ! great granophyre protrusions ( ! ,inn] ,hebrides1 b has made "s progress t[>ds ! detection ( a means ( di/+ui%+ ! two s]ies ev5 :]e no direct te/ ( _! relative age may be available4 ,he ?9ks t ! g5]al habit & petrographical *>act]s ( ! dykes may on fur!r inve/igation be f\nd to af=d a suffici5tly reliable basis = discrim9ation4 ,he f9ds t :]e ! relative ages ( ! dykes ) ref]5ce to ! granophyre c be fix$1 ! e>li] or pre-granophyre s]ies is )\t exception basic4 ,x consi/s ( f9e-textur$ basalts or diabases1 )\t any conspicu\s porphyritic cry/als4 ,its dykes are less regul> & p]si/5t 9 _! be>+ ?an ^? ( ! lat] s]ies2 h frequ5tly a consid]able hade1 ev5 z mu* z #de1 & (t5 %[ *ill$ edges ) ta*ylitic selvages4 ,9 ,skye _m ( ^! e>li] dykes may be connect$ ) ! gabbro4 ,!y appe> to be m basic & to h a high] specific gravity ?an ^? ( ! lat] s]ies :i* mo/ resemble !m4 ,! lat] or po/-granophyre dykes include sev]al types1 ! relative ages ( :i* are n yet def9itely fix$4 ,!y run 9 /raight p>allel l9es1 & ?us seldom int]sect ea* o!r4 ,!y are g5]ally v]tical or highly incl9$1 & are mu* m frequ5tly *>act]iz$ by amygdaloiclal /ructure ?an ! e>li] s]ies4 ,mr4 ,h>k] di/+ui%es ! foll[+ v>ieties among !m3 7a7 ,qu>tz-felsites & o!r acid rocks2 ^! are n v common4 7b7 ,pit*/ones & v>i\s sph]ulitic & v>iolitic rocks3 ! actual pit*/ones obs]v$ are comp>atively few 9 numb]1 b x is c]ta9 t "s ( sph]ulitic v>ieties are devitrifi$ pit*/ones4 7c7 ,basic rocks1 n conspicu\sly porphyritic & less decid$ly basic ?an ! dykes ( ! pre-granophyre s]ies2 mo/ ( ! lat] gr\ps come into ?is or ! next gr\p1 7d7 ,porphyritic basic dykes n infrequ5tly c>ry+ inclusions ( gabbro1 granophyre or o!r rocks4 ,! porphyritic felsp>s seem to be 9 great "p ( =eign d]ivation1 & ! same is c]ta9ly true ( ! augite :i* occasionally accompanies !m & ( ! qu>tz t appe>s 9 "s examples4#bji ,footnote #bji3 ,annual ,report ( ! ,director-,g5]al ( ! ,geological ,survey 9 ,report ( ,sci5ce & ,art ,dep>tm5t = #ahie4 ,9 ! ,c>l+=d di/rict ( ! ,nor?-ea/ ( ,irel&1 simil> evid5ce has be5 obta9$ t "o s]ies ( dykes prec$$ & ano!r foll[$ ! protrusion ( ! granites & granophyre :i* are 9 all probability geologically coeval ) ! acid bosses ( ! ,inn] ,hebrides4 ,! di/9ction 0 obs]v$ & mapp$ by ,mr4 ,traill = ! ,geological ,survey4 ,pr(essor ,sollas 9 rec5tly confirm+ ^! obs]vations has n notic$ any /rik+ diff]5ce betwe5 ! pre-granite & po/-granite dykes1 ! :ole appe>+ to consi/ ( ! same co>sely porphyritic mat]ial4#baj ,footnote #baj3 ,see ,%eets #ei1 #fj1 & #ga ( ! ,geological ,survey ,map ( ,irel&2 ,pr(essor ,sollas1 ,trans4 ,roy4 ,iri% ,acad4 vol4 xxx4 7#ahid71 p4 #dgg2 & ,annual ,report ( ! ,director-,g5]al ( ! ,geological ,survey = #ahie4 ,:ile ! eruption ( ! granophyre bosses furni%es pro( t ! dykes are n all ( ! same age1 o!r evid5ce may be ga!r$ to %[ h[ mu* old] "s ( ! dykes are ?an ! y\nge/ lava-/reams 9 ! volcanic hi/ory ( ,t]ti>y "t 9 ,brita94 ,! ,scuir ( ,eigg1 to :i* full] ref]5ce w be made 9 ,*apt] xxxviii41 is =m$ ( a mass ( pit*/one1 :i* has fill$ up an anci5t valley erod$ out ( ! t]rac$ basalts ( ! plateaux4 ,at bo? ends ( ! ridge1 ^! basalts are se5 to be trav]s$ by dykes t are abruptly cut (f by ! %+le ( ! old riv]-b$ :i* ! pit*/one has occupi$ 7,figs4 #bgi1 #bhb74 ,x is ?us evid5t t1 ?\gh ^! dykes are y\ng] ?an ! plateau-basalts1 !y are mu* old] ?an ! excavation ( ! valley out ( ^! basalts1 & /ill old] ?an ! eruption ( pit*/one4 ,! latt] rock probably belongs to ! close ( ! p]iod ( lava-eruptions4 ,! enorm\s d5udation ( ! basalt-plateaux aft] ! injection ( ! dykes & be=e ! outfl[ ( ! pit*/one af=ds a conv9c+ pro( ( ! va/ness ( ! int]val betwe5 ! eruption ( ! two k9ds ( rock4#baa ,footnote #baa3 ,qu>t4 ,j\r4 ,geol4 ,soc4 xiv4 p4 #a4 ,x is ?us demon/rable t ! dykes :i* 9 ,brita9 =m "p ( ! great ,t]ti>y volcanic s]ies1 7 n all produc$ at "o epo*1 b belong to at lea/ two 7& probably to _m m7 episodes 9 "o long volcanic hi/ory4 ,z !y rise ?r\gh e memb] ( t s]ies ( rocks 7save ! pit*/ones71 "s ( !m mu/ be among ! late/ records ( ! prolong$ volcanic activity4 ,b1 on ! o!r h&1 "s probably g back to ! v beg9n+ ( ! ,t]ti>y volcanic p]iod4 #bj4 ,,orig9 ,,& ,,hi/ory ,,( ,,! ,,dykes ,ref]5ce has already be5 made to ! d\bt express$ by ,maccullo* :e!r ! dykes 9 ,skye _h be5 fill$ 9 f above or f bel[4 ,t ! dykes ( ! c\ntry z a :ole 7 suppli$ f above1 0 ! view ent]ta9$ & en=c$ by ,b\4 ,he introduces ! subject ) ! foll[+ rem>ks3--,scotl& is r5[n$ = ! numb] ( its basaltic ve9s1 :i* gave ,hutton 8 ideas reg>d+ ! injection ( lava f bel[2 b1 z ! greate/ g5ius is n infallible1 & z volcanic c\ntries pres5t u ) examples ( su* ve9s aris+ evid5tly f accid5tal fissures t 7 fill$ up by curr5ts ( lava :i* mov$ ov] !m1 & z ! ,scotti% in/ances are ( ! same k9d1 we reg>d x z inf9itely probable t all ^! ve9s h be5 =m$ 9 ! same way not)/&+ ! enorm\s d5udation :i* ?is supposition involves2 & t only r>ely d cases occur :]e !y h be5 fill$ lat]ally or 9 "s o!r irregul> mann]4#bab ,i ne$ n say t ?is view1 :i*1 except among ,w]n]ians1 _h nev] _m support]s1 has long ago be5 ab&on$ & =gott54 ,!re is no fur!r "q t ! molt5 mat]ial came f bel[4 ,footnote #bab3 ,essai ,gologique sur l'cosse1 p4 #bgb4 #a4 ,9 discuss+ ! hi/ory ( ! dykes1 we are fir/ confront$ ) ! problem ( ! =mation ( ! fissures up :i* ! molt5 mat]ial rose4 ,f :at has be5 said above reg>d+ ! usual want ( relation betwe5 dykes & ! nature & arrangem5ts ( ! rocks :i* !y trav]se1 x is1 ,i ?9k1 manife/ t ! fissures c\ld n h be5 caus$ by any sup]ficial action1 su* z t :i* produces cracks ( ! gr\nd dur+ e>?quake-%ocks4 ,! fact t !y trav]se rocks ( ! mo/ extreme div]sities ( ela/icity1 /ructure1 & resi/ance1 & yet ma9ta9 ! same p]si/5t tr5d ?r\gh !m all1 %[s t !y orig9at$ f> bel[ ! limits to :i* ! kn[n rocks ( ! surface desc5d4 ,we h se5 t 9 ! case ( ! ,clevel& dyke1 ! fissure c be prov$ to be at lea/ "s ?ree miles deep4 ,b ! seat ( ! orig9 ( ! r5ts no d\bt lay mu* deep] d[n )9 ! e>?'s cru/4 ,x is also evid5t t ! cause :i* gave rise to ^! abundant fissures mu/ h be5 q di/9ct f ! movem5ts t produc$ ! preval5t /rike & ! ma9 faults ( ?is c\ntry4 ,f e>ly geological "t1 z is well kn[n1 ! movem5ts ( ! e>?'s cru/ b5ea? ! area ( ,brita91 h be5 direct$ 9 su* a mann] z to give ! diff]5t /ratifi$ =mations a g5]al nor?-ea/ & s\?-we/ /rike1 & to dislocate !m by great faults ) ! same av]age tr5d4 ,b ! fissures ( ! ,t]ti>y dykes run obliquely & ev5 at a "r angle across ?is preval5t old] s]ies ( l9es & are di/9ct f any o!r ar*itectonic feature 9 ! geology ( ! c\ntry4 ,!y did n arise !re=e by a m]e r5ewal ( "s previ\s ord] ( di/urbances1 b 7 br\ght ab\t by a new set ( movem5ts to :i* x is difficult to f9d any p>allel 9 ! e>li] records ( ! region4#bac ,footnote #bac3 ,! only o!r kn[n example ( su* a dyke-/ructure 9 ,brita9 is t ( ! ,pre-,cambrian s]ies ( dykes 9 ! ,lewisian gneiss ( ,su!rl&1 describ$ 9 ,*apt] viii4 ,we h fur!r to rememb] t ! fissures 7 n produc$ m]ely by "o great di/urbance4 ,! evid5ce ( ! dykes proves beyond "q t "s ( !m are e>li] ?an o!rs1 & h5ce t ! cause to :i* ! fissures ow$ _! orig9 came into op]ation repeat$ly dur+ ! protract$ ,t]ti>y volcanic p]iod4 ,"o ( ! mo/ in/ructive lessons 9 ?is respect is furni%$ by ! huge eruptive masses ( gabbro & granitoid rocks 9 ,skye4 ,^! mat]ials h be5 erupt$ ?r\gh ! plateau-basalts4 ,! granitoid bosses are ! y\ng] protrusions1 = !y s5d ve9s into ! gabbros2 b _! appe>ance 0 lat] ?an t ( "s ( ! dykes & old] ?an t ( o!rs4 ,nev]!less1 ! y\nge/ dykes g5]ally ma9ta9 ! usual nor?-we/]ly tr5d across ! ?icke/ masses ( ! granophyre4 ,?us we p]ceive t1 ev5 aft] ! extrusion ( ?\s&s ( feet ( su* solid cry/all9e igne\s rocks1 cov]+ areas ( _m squ>e miles1 ! fissur+ ( ! gr\nd 0 r5ew$1 & r5ts 7 op5$ ?r\gh ^! new piles ( mat]ial4 ,f ! evid5ce ( ! dykes also we le>n t "s fissures 7 repeat$ly re-op5$ & admitt$ a new asc5t ( molt5 magma betwe5 _! walls4 ,! g5]al direction ( ! fissures rema9$ f fir/ to la/ tol]ably uni=m4 ,"h & !re inde$1 :]e "o set ( dykes trav]ses ano!r1 z 9 ,skye & ! bas9 ( ! ,clyde1 we meet ) pro(s ( a deviation f ! normal tr5d4 ,b x is rem>kable t dykes :i* pi]ce ! late/ eruptive bosses ( ! ,inn] ,hebrides rose 9 fissures t 7 op5$ 9 ! normal nor?-we/]ly l9e ?r\gh ^! great protrusions ( basic & acid rock4 ,su* a gigantic sy/em ( p>allel fissures po9ts to great horizontal t5sion ( ! t]re/rial cru/ ov] ! area 9 :i* !y are develop$4 ,hopk9s1 _m ye>s ago1 discuss$ f ! ma!matical side ! cause ( ! production ( su* fissures4#bad ,he assum$ ! exi/5ce ( "s elevatory =ce act+ "u consid]able areas ( ! e>?'s cru/ at any assignable dep?1 ei!r ) uni=m int5sity at e po9t or ) a some:at great] int5sity at p>ticul> po9ts4 ,he did n assign to ?is =ce any def9ite orig91 b suppos$ x to act ^u ! l[] surface ( ! uplift$ mass ?r\gh ! m$ium ( "s fluid1 :i* may be conceiv$ to be an ela/ic vap\r1 or1 9 o!r cases1 a mass ( matt] 9 a /ate ( fusion f heat4#bae ,he %[$ t su* an upheav+ =ce w\ld produce 9 ! affect$ t]ritory a sy/em ( p>allel longitud9al fissures1 :i*1 :5 n f> di/ant f ea* o!r1 c\ld only h be5 =m$ simultane\sly1 & n successively2 t ea* fissure w\ld beg9 n at ! surface b at "s dep? bel[ x1 & w\ld be propagat$ ) great velocity2 t !re w\ld be m fissures at great] ?an at less] dep?s1 _m ( !m nev] rea*+ ! surface2 t !y w\ld be ( approximately uni=m wid?1 ! mean wid? t5d+ to increase d[nw>ds2 t cont9u$ elevation might increase ^! fissures1 b t new fissures 9 ! same direction w\ld n arise 9 ! sep>at$ blocks :i* w\ld n[ be m or less indep5d5t ( ea* o!r2 t subsequ5t subsid5ces w\ld give rise to transv]se fissures1 & by all[+ ! sep>at$ blocks to settle d[n w\ld cause irregul>ities 9 ! wid? ( ! great p>allel fissures4 ,he consid]$ also ! problem pres5t$ by ^? cases :]e ! ruptures ( ! t]re/rial cru/ h be5 fill$ ) igne\s matt]1 & n[ appe> z dykes4 ,! results above obta9$1 he says1 w manife/ly hold equally1 :e!r we suppose ! uplift$ mass act$ ^u imm$iately ?r\gh ! m$ium ( an ela/ic vap\r or by matt] 9 a /ate ( fusion 9 imm$iate contact ) its l[] surface4 ,9 ! latt] case1 h[ev]1 ?is fus$ matt] w necess>ily asc5d into ! fissures1 & if ma9ta9$ !re till x cools & solidifies1 w pres5t su* ph5om5a z we n[ recognize 9 dykes & ve9s ( trap4 ,footnote #bad3 ,cambridge ,phil4 ,trans4 vi4 7#ahce71 p4 #a4 ,footnote #bae3 ,ibid4 p4 #aj4 ,! exi/5ce ( a va/ lake or res]voir ( molt5 rock "u ! fissure-region ( ,brita9 is demon/rat$ by ! dykes4 ,b1 if we inquire fur!r :at t]re/rial op]ation l$ to ! uprise ( s va/ a body ( lava t[>ds ! surface 9 old] ,t]ti>y "t1 we f9d t z yet no satisfactory answ] c be giv54 #b4 ,9 "s di/ricts ! dykes c be connect$ ) ! gabbros :i* occur z intrusive sills & irregul> bosses 9 ! basalt-plateaux & among old] rocks4 ,! gabbros1 h[ev]1 are trav]s$ by /ill lat] dykes1 :i* mu/ !n be indep5d5t ( any visible mass ( ^! rocks4 ,! connection ( dykes ) ! gabbros is :at we might naturally expect to f9d1 if ! m co>sely cry/all9e rock repres5ts portions ( ! basic magma :i* consolidat$ at "s dep? bel[ ! surface4 ,if we c\ld p5etrate deep en\gh1 x is n improbable t ! dykes might be f\nd 9 l>ge measure to %ade d[nw>d into va/ bodies ( gabbro4 ,su* a relation has be5 obs]v$ 9 ! ,yell[/one di/rict1 :]e ,mr4 ,idd+s has notic$ t ! c5tre t[>d :i* ! dykes ( ! ,old ,cr&ale volcano conv]ge is a l>ge mass ( granul> gabbro1 pass+ into diorite1 ! dykes becom+ rapidly co>s] 9 gra9 z !y approa* ! gabbro-core4#baf ,footnote #baf3 ,j\rn4 ,geol4 i4 7#ahic71 p4 #fjh4 #c4 ,! rise ( molt5 rock 9 ?\s&s ( fissures ov] s wide a region is to my m9d by f> ! mo/ wond]ful feature 9 ! hi/ory ( volcanic action 9 ,brita94 ,! great plateaux ( basalt1 & ! m\nta9\s bosses ( rock by :i* !y h be5 disrupt$1 are und\bt$ly ! mo/ obvi\s memorials ( ,t]ti>y volcanism4 ,b1 aft] all1 !y are m]ely fragm5ts re/rict$ to limit$ di/ricts4 ,! dykes1 h[ev]1 reveal to u ! extraord9>y fact t1 at a p]iod s rec5t z old] ,t]ti>y "t1 !re lay und]nea? ! area ( ,brita9 a res]voir or s]ies ( res]voirs ( lava1 ! unit$ ext5t ( :i* mu/ h exce$$ #dj1jjj squ>e miles4 ,t ! mat]ial ( ! dykes rose 9 g5]al directly f bel[1 & 0 n1 except locally1 inject$ lat]ally along ! op5 fissures1 may be inf]r$1 al?\gh pro( ( su* lat]al injection on a small scale may "h & !re be detect$4 ,! n>r[ness ( ! r5ts1 & _! enorm\s relative l5g?1 make x physically impossible t molt5 rock c\ld h mov$ along !m = m ?an %ort di/ances4 ,! usual homog5e\s "* ( ! dyke-rocks1 ! rem>kable sc>city ( any brok5-up consolidat$ fragm5ts ( !m imm]s$ 9 a matrix ( diff]5t gra91 ! g5]al uni=mity ( composition & /ructure f "o end ( a long dyke to ano!r1 ! sph]ical =m ( ! amygdales1 ! usual paucity ( fragm5ts f ! fissure walls--all po9t to a quiet well+ ( ! lava upw>d4 ,ov] ! :ole ( ! region trav]s$ by ! dykes1 f ! hills ( ,york%ire & ,lanca%ire to ! remote/ ,hebrides1 molt5 rock mu/ h la9 at a dep?1 :i*1 9 "o case1 we "k to h exce$$ ?ree miles1 & :i* 0 probably ev]y:]e consid]ably great] ?an t limit4 ,=c$ upw>ds1 p>tly p]haps by pressure due to t]re/rial contraction & p>tly by ! enorm\s expansive =ce ( ! gases & vap\rs absorb$ )9 x1 ! lava rose 9 ?\s&s ( fissures t _h be5 op5$ = x 9 ! solid ov]ly+ cru/4 ,t 9 mo/ cases its asc5t t]m9at$ %ort ( ! surface ( ! gr\nd may reasonably be inf]r$4 ,at lea/1 we "k1 t _m dykes d n rea* ! pres5t surface1 & t ^? :i* d h %>$ 9 ! enorm\s d5udation ( ! surr\nd+ c\ntry4 ,t ev5 9 ! same dyke ! lava rose hundr$s ( feet high] at "o place ?an at ano!r is abundantly prov$4 ,:51 h[ev]1 we consid] ! va/ numb] ( dykes t n[ come to ! light ( day1 & reflect t ! visible portions ( "s ( !m diff] m ?an #cjjj feet f ea* o!r 9 altitude1 we c h>dly escape ! conviction t x w\ld be incr$ible t n[h]e %\ld ! lava h fl[$ out at ! surface4 ,subsequ5t d5udation has und\bt$ly remov$ a great ?ickness ( rock f :at 0 ! surface ( ! gr\nd dur+ old] ,t]ti>y "t1 & hundr$s ( dykes are n[ expos$ t d\btless orig9ally lay deeply buri$ b5ea? ! ov]ly+ "p ( ! e>?'s cru/ ?r\gh :i* !y fail$ to rise4 ,b "s relics1 at lea/1 ( ! outfl[ ( lava might be expect$ to h surviv$4 ,i believe t su* relics rema9 to u 9 ! great basalt-plateaux ( ,antrim & ! ,inn] ,hebrides4 ,^! deep piles ( almo/ horizontal %eets ( basalt1 emanat+ f no great c5tral volcanoes1 b ) evid5ce ( _m local v5ts1 appe> to me to h proce$$ 9 l>ge measure f dykes :i*1 communicat+ ) ! surface ( ! gr\nd1 all[$ ! molt5 mat]ial to fl[ out 9 successive /reams ) occasional accompanim5ts ( fragm5t>y ejections4#bag ,! /ructure ( ! basalt-plateaux1 & _! mode ( orig91 w =m ! subject ( ! next division ( ?is volume4 ,footnote #bag3 ,x is int]e/+ to note t 9 ! great pap] on ,physical ,geology already cit$1 ,hopk9s consid]$ ! "q ( ! outfl[ ( lava f ! fissures :i* he discuss$4 ,if ! quantity ( fluid matt] =c$ into ^! fissures1 he says1 be m ?an !y c conta91 x w1 ( c\rse1 be eject$ ov] ! surface2 & if ?is ejection take place f a consid]able numb] ( fissures1 & ov] a tol]ably ev5 surface1 x is easy to conceive ! =mation ( a b$ ( ! eject$ matt] ( mod]ate & tol]ably uni=m ?ickness1 & ( any ext5t 7op4 cit4 p4 #ga74 ,we c h>dly suppose t ! lava fl[$ out only 9 ! we/]n region ( ! exi/+ plateaux4 ,probably x 0 mo/ frequ5tly emitt$ & accumulat$ to ! greate/ dep? 9 t area4 ,b ov] ! c5tre ( ,scotl& & ,nor? ( ,engl& !re may well h be5 _m places :]e dykes actually communicat$ ) ! out] air1 & all[$ _! molt5 mat]ial to /ream ov] ! surr\nd+ c\ntry1 ei!r f op5 fissures or f v5ts t rose along ^!4 ,! disappe>ance ( su* outfl[s ne$ cause no surprise1 :5 we consid] ! ext5t ( ! d5udation :i* _m dykes demon/rate4 ,i h else:]e %[n t all ov] ,scotl& !re is abundant pro( t hundr$s & ev5 ?\s&s ( feet ( rock h be5 remov$ f p>ts ( ! surface ( ! l& s9ce ! "t ( ! uprise ( ! dykes4#bah ,! evid5ce ( ?is d5udation is s+ul>ly /rik+ 9 su* di/ricts z t ( ,lo* ,lomond1 :]e ! diff]5ce ( level betwe5 ! outcrop ( ! dykes on ! cre/ ( ! ridges & 9 ! bottom ( ! valleys exce$s #cjjj feet4 ,x is q obvi\s1 = example1 t _h ! deep holl[ ( ,lo* ,lomond la91 z x n[ does1 9 ! pa?way ( ^! dykes1 ! molt5 rock1 in/ead ( asc5d+ to ! summits ( ! hills1 w\ld h bur/ out on ! floor ( ! valley4 ,we are1 !re=e1 =c$ to admit t a deep gl5 & lake-bas9 h be5 9 great measure holl[$ out s9ce ! "t ( ! dykes4 ,if a dep? ( _m hundr$s ( feet ( h>d cry/all9e s*i/s c\ld h be5 remov$ 9 ! int]val1 !re ne$ be no difficulty 9 und]/&+ t by ! same process ( wa/e1 _m %eets ( solid basalt may h be5 gradually /ripp$ (f ! face ( ,c5tral ,scotl& & ,nor!rn ,engl&4 ,footnote #bah3 ,sc5]y ( ,scotl&1 #bnd edit4 7#ahhg71 p4 #adi4 ,b see ! rem>ks already made 7p4 #aej7 on ! curi\s co9cid5ce sometimes obs]vable betwe5 ! upp] limit ( a dyke & ! ov]ly+ inequalities ( surface4 ,! association ( fissures & dykes ) ! accumulation ( ?ick & ext5sive volcanic plateaux1 ov] s wide a region ( ,nor?-we/]n ,europe z f ,antrim to ! ,nor? ( ,icel&1 f9ds its p>allel 9 diff]5t p>ts ( ! _w4 ,"o ( ! close/ analogies pres5ts itself among ! ,ghauts ( ! ,bombay ,presid5cy1 :]e va/ basaltic %eets1 probably ( ,cretace\s age1 display topographical & /ructural features closely simil> to ^? ( ! ,t]ti>y volcanic plateaux ( ! ,briti% ,isles4 ,! dykes connect$ ) ^! ,indian basaltic outfl[s correspond almo/ exactly 9 _! g5]al "* & /ratigraphical relations to ^? ( ?is c\ntry4 ,!y occur 9 great numb]s1 ris+ ?r\gh e rock 9 ! di/rict up to ! cre/s ( ! ,ghauts1 #djjj feet above ! sea4 ,!y v>y f #a or #b to #aj1 #bj1 #dj1 & ev5 occasionally #ajj or #aej feet 9 wid?1 & are (t5 _m miles 9 l5g?4 ,!y obs]ve a g5]al p>allelism 9 "o av]age direction1 & %[ no p]ceptible diff]5ce 9 "* ev5 :5 trac$ up to elevations ( #cjjj & #djjj feet4#bai ,footnote #bai3 ,mr4 ,g4 ,t4 ,cl>k1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxv4 7#ahfi7 p4 #afc4 ,= rem>ks on ! connection ( dykes ) sup]ficial lavas1 see po/ea1 p4 #bfh4 ,?\s&s ( squ>e miles 9 ! ,we/]n ,/ates & ,t]ritories ( ! ,am]ican ,union h be5 simil>ly flood$ ) basic lavas4 ,d5udation has n yet advanc$ f> en\gh to lay b>e mu* ( ! plat=m on :i* ^! lavas re/4 ,b ! dykes t trav]se ! rocks outside ( ! lava-des]ts af=d an example ( ! /ructure :i* w ultimately be reveal$ :5 ! wide & cont9u\s basalt-pla9s %all h be5 tr5*$ by innum]able valleys & r$uc$ to fragm5t>y plateaux ) l(ty esc>pm5ts 7p4 #bfg74 ,x is to ! mod]n eruptions ( ,icel&1 h[ev]1 t we turn = ! complete/ illu/ration ( ! ph5om5a connect$ ) dykes & fissures4 ,an acc\nt ( ^! eruptions w !re=e be giv5 9 ,*apt] xl4 z an explanation ( ! hi/ory ( ! ,t]ti>y basalt-plateaux ( ,brita94 ,,*apt] ,,xxxvi ,,! ,,plateaux ,nature & ,arrangem5t ( ! ,rocks3 #a4 ,lavas4--,basalts1 ,dol]ites1 ,&esites--,/ructure ( ! ,lavas 9 ! ,field--#b4 ,fragm5tal ,rocks4--,agglom]ates1 ,conglom]ates1 & ,breccias--,tuffs & _! accompanim5ts4 ,we h n[ to consid] ! /ructure & hi/ory ( ^? volcanic masses :i*1 dur+ ,t]ti>y "t1 7 eject$ to ! surface )9 ! area ( ! ,briti% ,isl&s1 & n[ rema9 z ext5sive plateaux4 ,%ort ?\gh ! int]val has be5 9 a geological s5se s9ce ^! rocks 7 erupt$1 x has be5 long en\gh to all[ ( v consid]able movem5ts ( ! gr\nd & ( enorm\s d5udation1 z w be m fully discuss$ 9 ,*apt]s xlviii4 & xlix4 ,h5ce ! sup]ficial records ( ,t]ti>y volcanic action h be5 r$uc$ to a s]ies ( brok5 & isolat$ fragm5ts4 ,i h already /at$ t no evid5ce n[ rema9s to %[ to :at ext5t !re 7 actual sup]ficial outbur/s ( volcanic mat]ial ov] mu* ( ! dyke-region ( ,brita94 ,! subsequ5t wa/e ( ! surface has be5 s enorm\s t v>i\s lava-fields may q possibly h /ret*$ across p>ts ( ,engl& & ,scotl&1 :5ce !y h s9ce be5 :olly /ripp$ (f1 leav+ beh9d !m only t wond]ful sy/em ( dykes f :i* _! molt5 mat]ials 7 suppli$4 ,!re c be little d\bt1 h[ev]1 t :e!r or n o!r ,phlegrean fields ext5d$ ov] portions ( ! c\ntry :5ce !y h s9ce be5 worn away1 ! *ief volcanic tract lay 9 a broad & long holl[ t /ret*$ f ! s\? ( ,antrim to ! ,m9*4 ,f ! s\!rn to ! nor!rn limit ( ! fragm5t>y lava-fields t rema9 9 ?is depression is a di/ance ( "s #bej miles1 & ! av]age bread? ( gr\nd )9 :i* ^! lava-fields are pres]v$ may be tak5 to range f #bj to #ej miles4 ,if1 !re=e1 ! %eets ( basalt & lay]s ( tuff ext5d$ ov] ! :ole ( ?is /rip ( c\ntry1 !y cov]$ a space ( "s #gjjj or #hjjj squ>e miles4 ,b !y 7 n conf9$ to ! area ( ! ,briti% ,isl&s4 ,simil> rocks rise into an ext5sive plateau 9 ! ,f>oe ,isl&s1 & x may reasonably be conjectur$ t ! rem>kable subm>9e ridge :i* ext5ds !nce to ! ,nor?-we/ ( ,scotl&1 & sep>ates ! bas9 ( ! ,atlantic f t ( ! ,arctic ,ocean1 is p>tly at lea/ ( volcanic orig94 ,/ill fur!r nor? come ! ext5sive ,t]ti>y basaltic plateaux ( ,icel&1 :ile o!rs ( l aspect & age cov] a va/ area 9 ,s\!rn ,gre5l&4 ,)\t cont5d+ t "o cont9u\s belt ( lava-/reams /ret*$ f ,irel& to ,icel& & ,gre5l&1 we c h no d\bt t 9 old] ,t]ti>y "t ! nor?-we/ ( ,europe 0 ! sc5e ( m widely-ext5d$ volcanic activity ?an _h %[n itself at any previ\s p]iod 9 ! geological hi/ory ( ! :ole cont95t4 ,! pres5t active v5ts ( ,icel& & ,jan ,may5 are n improbably ! desc5dants 9 un9t]rupt$ succession ( ^? t suppli$ ! mat]ials ( ! ,t]ti>y basaltic plateaux1 ! volcanic fires sl[ly dy+ out f s\? to nor?4 ,b s cont9u\s & /up5d\s has be5 ! "w ( d5udation 9 ^! nor!rn regions1 :]e w9ds & waves1 ra9 & fro/1 floe-ice & glaci]s rea* _! highe/ level ( en]gy1 t ! pres5t ext5sive %eets ( igne\s rock c be reg>d$ only z magnific5t relics1 ! gr&eur ( :i* furni%es "s measure ( ! magnitude ( ! la/ episode 9 ! ext5d$ volcanic hi/ory ( ,brita94 ,! long & wide we/]n valley 9 :i* ! basalt-plateaux ( ?is c\ntry 7 accumulat$ seems1 f a remote antiquity1 to h be5 a !atre ( consid]able geological activity4 ,!re are traces ( "s su* valley or depression ev5 back 9 ! p]iod ( ! ,torridon ,s&/one ( ! nor?-we/4 ,?is =mation1 z we h se51 0 laid d[n betwe5 ! great ridge ( ! ,out] ,hebrides & "s o!r l& to ! ea/1 ( :i* a few ( ! high] m\nta9s1 once buri$ "u ! s&/one1 are n[ be+ reveal$ by d5udation betwe5 ,lo* ,m>ee & ,lo* ,broom1 & also 9 ,assynt4 ,! conglom]ates & volcanic rocks ( ,lorne may repres5t ! site ( "o ( ! old] wat]-bas9s ( ?is anci5t holl[4 ,! ,c>bonif]\s rocks1 :i* run ?r\gh ! ,nor? ( ,irel&1 cross into ,cantyre1 & are f\nd ev5 z f> nor? z ! ,s\nd ( ,mull1 m>k h[1 9 lat] ,palozoic "t1 ! same /rip ( c\ntry 0 a region ( subsid5ce & s$im5tation4 ,dur+ ! ,mesozoic ages1 simil> op]ations 7 cont9u$2 ! holl[ sank sev]al ?\s& feet1 & ,jurassic /rata to t dep? fill$ x up4 ,be=e ! ,cretace\s p]iod1 und]gr\nd movem5ts _h disrupt$ & irregul>ly upheav$ ! ,jurassic deposits1 & prolong$ d5udation _h worn !m away1 s t :5 ! ,cretace\s =mations came to be laid d[n on ! once m subsid+ depression1 !y 7 spread out ) a /rong uncon=mability on ev]y?+ old] ?an !mselves1 re/+ on _m successive horizons ( ! ,jurassic sy/em1 & pass+ f ^! ov] to ! subm]g$ hillsides ( ! cry/all9e s*i/s4 ,yet aga91 aft] ! accumulation ( ! ,*alk1 ! sea-floor along ! same l9e 0 ridg$ up into l&1 & ! ,*alk1 expos$ to d5udation1 0 deeply tr5*$ by valleys1 & entirely remov$ f wide tracts :i* x once cov]$4 ,x 0 9 ?is long broad holl[1 ) its memorials ( repeat$ subsid5ces & upheavals1 s$im5tation & d5udation1 t ! vig\r ( subt]ranean en]gy at la/ %[$ itself 9 volcanic outbreaks1 & 9 ! gradual pil+ up ( ! mat]ials ( ! basalt-plateaux4 ,s f> z we "k1 ^! outbur/s 7 subrial4 ,at lea/ no trace ( any m>9e deposit has yet be5 f\nd ev5 at ! base ( ! pile ( volcanic rocks4 ,%eet aft] %eet ( lava 0 p\r$ out1 until sev]al ?\s& feet _h accumulat$1 s z p]haps to fill up ! :ole depression1 & once m to *ange entirely ! aspect ( ! region4 ,b ! volcanic p]iod1 long & important z x 0 9 ! geological hi/ory ( ! c\ntry1 came to an end4 ,x1 too1 0 m]ely an episode dur+ :i* d5udation /ill cont9u$ active1 & s9ce :i* subt]ranean di/urbance & sup]ficial erosion h aga9 trans=m$ ! topography4 ,9 w&]+ ov] ^! anci5t lava-fields1 we see on e h& ! mo/ /up5d\s evid5ce ( *ange4 ,!y h be5 dislocat$ by faults1 sometimes ) a displacem5t ( hundr$s ( feet1 & h be5 holl[$ out into deep & wide valleys & arms ( ! sea4 ,_! piles ( solid rock1 hundr$s ( feet ?ick1 h be5 totally /ripp$ (f f wide tracts ( gr\nd :i* 7 once und\bt$ly buri$ "u !m4 ,h5ce1 late ?\gh ! volcanic ev5ts are 9 ! long hi/ory ( ! l&1 !y are already sep>at$ f u by s va/ an int]val t !re has be5 "t = cutt+ d[n ! wide plateaux ( basalt into a s]ies ( m]e scatt]$ fragm5ts4 ,b ! process ( l&-sculpture has be5 ( ! utmo/ s]vice to geology1 =1 by lay+ b>e ! inn] /ructure ( ^! plateaux1 x has provid$ mat]ials ( almo/ unequall$ value & ext5t = ! /udy ( "o type ( volcanic action4 ,i4 ,,nature ,,& ,,arrangem5t ,,( ,,! ,,rocks ,,( ,,! ,,plateaux ,! sup]ficial outbur/s ( volcanic action dur+ ,t]ti>y "t 9 ,brita9 are repres5t$ by a comp>atively small v>iety ( rocks4 ,^! consi/ almo/ :olly ( basalts1 b include a numb] ( less basic rocks :i* may be class$ z &esites4 ,_m &esitic %eets1 l ! &esitic dykes1 h be5 intrud$ into ! basalts1 & are really sills4 ,besides ! lavas ( ! basaltic-plateaux !re are int]calat$ deposits ( tuffs & breccias & l>ge masses ( agglom]ate4 ,a brief notice ( ! g5]al petrography ( ! v>i\s con/itu5ts ( ! plateaux & _! mode ( occurr5ce w "h be giv54 ,! intrusive bosses :i* h disrupt$ ! sup]ficial lavas w be discuss$ 9 subsequ5t *apt]s4 i4 ,,lavas #a4 ,petrographical ,*>act]s 7a7 ,basalts & ,dol]ites4--,9 ext]nal *>act]s ^! rocks range f co>sely cry/all9e v>ieties1 9 :i* ! con/itu5t m9]als may be m or less readily detect$ ) ! nak$ eye or a field-l5s1 to d5se black comp\nds 9 :i* only a few porphyritic cry/als may be megascopically visible4 ,"o ( _! *>act]i/ic features is ! pres5ce ( ! ophitic /ructure1 sometimes only feebly develop$1 sometimes %[+ itself 9 great p]fection4 ,_m ( ! rocks are holocry/all9e1 b usually %[ m or less int]/itial matt]2 9 o!rs ! texture is f9]1 & ! int]/itial matt] m develop$2 9 no case1 z f> z ,i h obs]v$1 are !re any glassy v>ieties1 :i* are re/rict$ to ! dykes & sills1 ?\gh 9 "s ( ! basalts ! proportion ( glassy or incompletely devitrifi$ sub/ance is consid]able4 ,! felsp>s are g5]ally ( ! *>act]i/ic la?-%ap$ =ms1 & are usually q cle> & fre%4 ,! augite resembles t ( ! dykes1 occurr+ sometimes 9 l>ge plates t enclose ! felsp>s1 at o!r times 9 a f9ely granul> =m4 ,oliv9e is frequ5tly n to be detect$1 ev5 by gre5 alt]ation products4 ,magnetite is sometimes pres5t 9 su* quantity z to affect ! compass ( ! field-geologi/4 ,porphyritic v>ieties occur ) l>ge felsp> ph5ocry/s2 b su* v>ieties are1 ,i ?9k1 less frequ5t among ! plateau-rocks ?an among ! dykes4 ,!y are well develop$ 9 ! we/ "p ( ! isl& ( ,canna1 & h be5 describ$ f ! ,f>oe isl&s4 ,occasionally ! plateau lavas are full ( enclos$ fragm5ts ( o!r rocks :i* h be5 c>ri$ up 9 ! asc5d+ magma4 7b7 ,&esites & ,tra*ytes4--,probably ! majority ( ^! rocks :]e !y occur int]calat$ betwe5 ! basalts ( ! plateaux are1 z already rem>k$1 intrusive %eets r ?an true lavas4 ,b !y h also be5 p\r$ out int]mitt5tly among ! basalts & dol]ites4 ,! mo/ ext5sive developm5t ( lavas :i* are readily di/+ui%able f ! gr\p ( plateau-basalts1 & mu/ be plac$ 9 ! pres5t s]ies1 occurs 9 ! isl& ( ,mull4 ,^! rocks =m "p ( a gr\p ( pale lavas :i* ov]lie ! ma9 mass ( ! plateau-basalts1 & cap ! m\nta9 ,b5 ,m1 toge!r ) sev]al ( its l(ty neighb\rs4 ,!y are int]/ratifi$ ) true ophitic dol]ites1 & basalts %[+ *>act]i/ic granul> augite4 ,!y are n s heavy z ! ord9>y plateau-lavas1 _! specific gravity rang+ f #bee to #bgd4 ,ext]nally !y are light grey 9 col\r & dull 9 texture1 sometimes /rongly amygdaloidal1 sometimes ) a rem>kable platy /ructure1 :i*1 9 ! process ( wea!r+1 causes !m to split up l /ratifi$ rocks4 ,9 "s ( _! amygdaloidal v>ieties ! cells are fill$ ) epidote1 :i* also appe>s 9 ! fissures1 & sometimes ev5 z a con/itu5t ( ! rock4 ,specim5s f ?is pale gr\p ( ,b5 ,m1 :5 exam9$ 9 ?9 slices "u ! microscope1 7 f\nd by ,dr4 ,hat* to consi/ almo/ :olly ( felsp> 9 m9ute la?s or microlites1 b 9 no in/ance suffici5tly def9ite = satisfactory det]m9ation4 ,9 "o ( !m he obs]v$ t ea* la? ( felsp> pass$ imp]ceptibly into ^? adjac5t to x2 ! d\ble refraction be+ v weak1 & ! tw9-/riation1 if pres5t1 n be+ traceable4#bbj ,m rec5tly my colleague1 ,mr4 ,w4 ,w4 ,watts1 has look$ at "s ( ! same slides4 ,he is dispos$ to class ! rocks r ) ! tra*ytes ?an ! &esites4 ,he rem>ks t 9 ! app>5t holocry/all9e "*1 ! size & %ape ( ! felsp>s1 ! sort ( damasc5$ appe>ance 9 pol>iz$ light1 ! f9ely scatt]$ iron-ores & ! pres5ce ( a pale gre5 hornbl5de1 possibly augite1 9 small1 (t5 complex1 gra9s1 ^! rocks mu* resemble ! ,c>bonif]\s tra*ytes ( ! ,g>lton ,hills 9 ,scotl&4 ,footnote #bbj3 ,9 ! c\rse ( my inve/igations ,i h _h _m hundr$s ( ?9 slices cut f ! ,t]ti>y volcanic rocks = microscopic det]m9ation4 ,^! ,i h myself /udi$ 9 s f> z _! microscopic /ructure appe>$ likely to aid 9 ! inve/igation ( ^? l>g] que/ions ( geological /ructure 9 :i* ,i 0 m especially int]e/$4 ,b = fur!r & m detail$ /udy ,i plac$ !m ) ,dr4 ,hat*1 :o submitt$ to me ! results ( 8 prelim9>y exam9ation1 & :]e ^! (f]$ po9ts ( geological import ,i avail$ myself ( !m 9 ! memoir publi%$ 9 #ahhh 9 ! ,transactions ( ! ,royal ,society ( ,ed9burgh4 ,i h reta9$ mo/ ( ^! citations 9 _! place 9 ! pres5t volume1 & h supplem5t$ !m by notes suppli$ to me f fre% obs]vations by ,mr4 ,watts & ,mr4 ,h>k]4 ,pr(essor ,judd1 9 a s]ies ( valuable pap]s1 has discuss$ ! g5]al petrography ( ! ,t]ti>y volcanic rocks 7,qu>t4 ,j\r4 ,geog4 ,soc4 vols4 xxxix4 xli4 xlii4 xlvi4 xlix47 ,"o ( ! mo/ int]e/+ lavas ( ! ,t]ti>y volcanic s]ies is ! pit*/one-porphyry ( ! ,scuir ( ,eigg4 ,?is rock1 ! late/ kn[n outfl[ ( lava 9 any ( ! volcanic areas ( ,brita91 0 =m]ly class$ ) ! acid s]ies4 ,microscopical & *emical analyses prove x1 h[ev]1 to be ( int]m$iate composition1 & to be ref]able to ! &esites or dacites4 ,x is m p>ticul>ly describ$ 9 ,*apt] xxxviii4 ,pr(essor ,judd1 collect+ ! &esitic rocks z a :ole 7bo? lavas & sills71 has gr\p$ !m into amphibole & mica-&esites1 & pyrox5e-&esites4#bba ,! ?ick lumpy & non-p]si/5t %eets ( ^! rocks sometimes f\nd ne> ! c5tres ( protrusion ( ! gabbros & granophyres are probably sills4 ,footnote #bba3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlvi4 7#ahij71 p4 #cef4 ,pr(essor ,judd has !re describ$ "u ! "n ( propylites v>i\s memb]s ( ! volcanic s]ies :i* he believes to h und]gone alt]ation f solfat>ic action4 ,i h n be5 able to discov] any trace ( su* action1 b ,i h f\nd t ! lavas ( ! plateaux assume a peculi> condition :]e !y h be5 affect$ by l>ge intrusive masses ( granophyre or gabbro4 7,see po/ea1 ,*apt] xlvi47 7c7 ,rhyolites4--,9 ! ,antrim plateau a gr\p ( rhyolite bosses occurs1 "s ( :i* h be5 claim$ z sup]ficial lavas4 ,9 "s cases x c be demon/rat$ t !y are intrusive1 & 9 no in/ance c !y be decisively %[n to h escap$ 9 /reams at ! surface4 ,x is probable1 h[ev]1 t "s ( ^! bosses did actually communicate ) ! out] air1 = betwe5 ! l[] & upp] gr\p ( basalts 9 ?is plateau1 b&s ( rhyolitic conglom]ate occur :i* may indicate ! degradation ( expos$ masses ( rhyolite4 ,! description ( ^! ,antrim bosses w be giv5 9 ,*apt] xlvii41 9 connection ) ! acid eruptive rocks ( ! ,t]ti>y volcanic s]ies4 #b4 ,/ructure 9 ! ,field ,pass+ n[ to ! consid]ation ( ! lavas z !y are built up into ! plateaux1 we h to note _! di/9ctive *>act]s z individual %eets ( rock1 & _! influ5ce on ! topography ( ! regions 9 :i* !y occur4 ,e t\ri/ :o has sail$ along ! cliffs ( ,antrim1 ,mull1 ,skye1 or ! ,f>oe ,isl&s is famili> ) ! s+ul> t]rac$ /ructure ( ! great volcanic esc>pm5ts :i* /ret* z mural precipices along ^! picturesque %ores4 ,successive %eets ( lava1 ei!r horizontal or only g5tly incl9$1 rise above ea* o!r f base to summit ( ! cliffs z p>allel b>s ( br[n rock ) int]v5+ /rips ( bright gre5 grassy slope4 ,! geologi/ :o = ! fir/ "t visits ^! coa/-l9es is impress$ by ! p]si/5ce ( ! same li?ological *>act]s giv+ rise to ! same topographical features4 ,he soon realises t ! plateaux1 s impos+ly truncat$ by ! great esc>pm5ts t spr+ f ! edge ( ! sea1 are built up ess5tially ( d>k lavas--basalts & dol]ites--& t fragm5tal volcanic accompanim5ts1 ?\gh "h & !re well develop$1 play1 on ! :ole1 a q insignificant "p 9 ! /ructure & composition ( ^! ?ick piles ( volcanic mat]ial4 ,clos] exam9ation 9 ! field enables him to asc]ta9 t1 reg>d$ z rock-masses1 ! lavas include f\r di/9ct types3-- #a/4 ,?ick1 massive1 prismatic or rudely-jo9t$ %eets1 r m co>sely cry/all9e & obvi\sly m durable ?an ! o!r types1 inasmu* z !y project 9 tabul> l$ges & t5d to reta9 p]p5dicul> faces ow+ to ! fall+ away ( slices ( ! rock along l9es ( v]tical jo9ts4 ,_m rocks ( ?is type are und\bt$ly intrusive %eets1 & z su* w be fur!r ref]r$ to 9 a lat] *apt]4 ,b ! type includes also true sup]ficial lavas :i* %[ ! *>act]i/ic slaggy or vesicul> b&s at _! upp] & l[] surfaces4 ,! m]e pres5ce ( su* b&s may n be en\gh1 inde$1 absolutely to e/abli% t ! rock possess+ !m fl[$ at ! surface z a lava1 = !y are occasionally1 ?\gh x mu/ be confess$ r>ely1 exhibit$ by true sills4 ,b ! r\gh scoriace\s top ( a lava-/ream1 & ! pres5ce ( fragm5ts ( ?is surface 9 ! ov]ly+ tuff1 or wrapp$ r\nd by ! next succe$+ lava1 suffici5tly atte/ ! true sup]ficial outfl[ ( ! mass4 #bnd4 ,prismatic or column> basalts1 :i*1 z at ! ,giant's ,causeway & ,/affa1 h long attract$ notice z "o ( ! mo/ /rik+ topographical elem5ts ( ! plateaux4 ,column> /ructures are typical ( ! m compact heavy basalts4 ,a consid]able v>iety is obs]vable 9 ! degree ( p]fection ( _! developm5t4 ,:]e !y are lea/ def9ite1 ! rock is trav]s$ by v]tical jo9ts1 some:at m regul> & close-set ?an ^? 9 ! dol]ites1 by ! int]section ( :i* x is sep>at$ into rude quadrangul> or polygonal columns4 ,! true column> /ructure is %[n 9 two *ief =ms4 7a7 ,! rock is divid$ into close-fitt+ p>allel1 usually six-sid$ columns2 ! numb] ( sides v>y+1 h[ev]1 f ?ree up to n9e4 ,! columns run ! :ole ?ickness ( ! b$1 & v>y f #h or #aj to #dj or ev5 #hj feet 9 l5g?4 ,!y are segm5t$ by cross jo9ts :i* sometimes1 z at ,giant's ,causeway1 take ! ball-&-socket =m4 ,occasionally !y are curv$1 z at ! well-kn[n ,clam-%ell cave ( ,/affa4 7b7 ,! prisms are mu* small]1 & div]ge 9 wavy gr\ps cr[d$ confus$ly ov] ea* o!r1 b ) a g5]al t5d5cy upw>ds4 ,?is />*-l aggregation may be obs]v$ sup]pos$ directly ^u ! m regul> column> =m z at ! ,giant's ,causeway & also at ,/affa4 ,excell5t illu/rations ( bo? ^! types may be se5 at _m po9ts along ! sea-cliffs ( ! ,inn] ,hebrides2 ! we/]n coa/ ( ,skye1 ! s\?-we/ side ( ,mull1 & ! cliffs ( ! isl& ( ,canna may be specially cit$4 ,illu/ration3 ,fig4 #bei4--,section ( scoriace\s & prismatic ,basalt1 ,camas ,?>b]ni%1 nor? %ore ( ,canna ,isl&4 ,?\gh g5]ally r compact1 becom+ inde$ d5se1 almo/ vitre\s rocks 9 "s %eets1 ! column> basalts are (t5 m or less cellul> ?r\gh\t1 & highly slaggy along _! upp] & "u surfaces4 ,9 "s cases1 z 9 t ( a prismatic %eet :i* ov]lies ! r\gh scoriace\s lava ( ,camas ,?>b]ni%1 9 ! isl& ( ,canna1 ! r[s ( vesicles are dispos$ 9 l9es p>allel to ! "u surface ( ! %eet 7,fig4 #bei47 ,z already rem>k$ ) reg>d to ! massive1 rudely-jo9t$ %eets1 _m ( ! mo/ p]fectly column> rocks ( ! plateaux are n sup]ficial lavas1 b intrusive sills1 bosses or dykes4 ,conspicu\s examples ( su* sills are display$ on ! coa/ ( ,trott]ni% 9 ,skye1 & ( ! bosses & dykes at ! ea/]n end ( ,canna4 ,to ^! fur!r ref]5ce w be made 9 ! sequel4 ,x is n always possible to be c]ta9 t column> %eets :i* appe> to be regul>ly int]calat$ among ! und\bt$ lavas ( ! volcanic s]ies may n be really intrusive4 ,9 "s in/ances1 inde$1 we c demon/rate t !y are s1 :5 aft] cont9u+ p]fectly p>allel ) ! lavas above & bel[ !m1 !y ev5tually break across !m4 ,"o ( ! mo/ rem>kable examples ( ?is feature is suppli$ by ! great sill ( ! s\?-we/ ( ,/rom1 9 ! ,f>oe ,isl&s1 ( :i* ,i %all give "s acc\nt 9 ,*apt] xlii4 7,figs4 #cab1 #cbh1 #cbi74 #crd4 ,slaggy or amygdaloidal lavas )\t any regul> jo9t$ /ructure1 b (t5 ) r\ghly scori=m upp] & "u lay]s1 & t5d+ to decay into br[n e>?y debris4 ,"s ( ! upp] surfaces ( su* %eets among ! ,t]ti>y basalt-plateaux mu/ h resembl$ ! s-call$ ,aa ( ! ,s&wi* ,isl&s4 ,a /rik+ example ( ! /ructure may be notic$ at ,camas ,?>b]ni%1 on ! nor? coa/ ( ! ,isl& ( ,canna4 ,!re ! hummocks on ! upp] surface ( a slaggy basalt measure ab\t #ae feet 9 bread?1 & rise ab\t ?ree feet above ! holl[s betwe5 !m1 l a succession ( waves 7see ,fig4 #bei74 ,! /eam-holes are dispos$ 9 a g5]al direction p>allel to ! /rike ( ! hummocks4 ,great v>iety obta9s 9 ! size & %ape ( ! vesicles4 ,huge cavities a foot or m 9 diamet] may occasionally be f\nd1 & f su* extremes e gradation may be trac$ d[n to m9ute pore-l vacuoles t c h>dly be made out ev5 ) a /rong l5s4 ,9 reg>d to ! de=mation ( ! vesicles1 x is a famili> g5]al rule t !y h be5 drawn out 9 ! direction ( ! fl[ ( ! orig9al lava4 ,occasionally !y h become /raight1 n>r[1 sometimes bifurcat+ pipes1 sev]al in*es long1 & only an eigh? ( an in* or s 9 diamet]4#bbb ,a numb] ( su* pipes1 p>allel to ea* o!r1 resembles a r[ ( worm-burr[s 7see ,fig4 #b74 ,footnote #bbb3 ,"s examples h be5 deposit$ by me 9 ! ,museum ( ,practical ,geology1 ,j]myn ,/reet1 9 ! case illu/rat+ rock-/ructures4 ,! elongation ( ! vesicles into annelide-l tubes may also be obs]v$ among ! /ones 9 ! volcanic agglom]ates4 ,x may (t5 be notic$ t1 ev5 :]e ! basalt is mo/ p]fectly prismatic1 x pres5ts a cellul> & ev5 slaggy /ructure at ! bottom4 ,! rock t =ms ! ,giant's ,causeway1 = in/ance1 is di/9ctly vesicul>1 ! vesicles be+ drawn out 9 a g5]al ea/ & we/ direction4 ,! beautiful column> b$ ( ,/affa is likewise slaggy & amygdaloidal = a foot or s upw>ds f its base1 & portions ( ?is l[] lay] h "h & !re be5 caught up & involv$ 9 ! m compact mat]ial above x4 ,ev5 ! bottom ( ! confus$ly prismatic b$ above ! column> "o on t isl& also pres5ts a cellul> texture4 ,a simil> rock at ,ardtun1 9 ,mull1 passes upw>d into a rugg$ slag & confus$ mass ( basalt blocks1 ov] :i* ! leaf-b$s lie4 ,amygdaloidal /ructure is m or less develop$ ?r\gh\t ! :ole s]ies ( basalts4 ,b x is especially m>k$ 9 c]ta9 abundant %eets1 :i*1 = ! sake ( di/9ction1 are call$ amygdaloids4 ,^! b$s1 :i* =m a consid]able proportion ( ! mat]ials ( e "o ( ! plateaux1 are di/+ui%$ by ! abundance & l>ge size ( _! vesicles4 ,9 "s places1 ! cavities occupy at lea/ z mu* ( ! rock z ! solid matrix 9 :i* !y lie4 ,!y h g5]ally be5 fill$ up ) "s infiltrat$ m9]al--calcite1 *alc$ony1 zeolites1 etc4 ,! amygdales ( ! we/ ( ,skye & ( ,antrim h long be5 not$ = _! zeolites4 ,z a consequ5ce ( _! cellul> texture & ! action ( infiltrat+ wat] ^u !m1 ^! amygdaloidal %eets are always m or less decompos$4 ,_! dull1 lumpy1 amorph\s aspect contra/s well ) ! %>ply-def9$ column> %eets above & bel[ !m1 & z !y crumble d[n !y are apt to be cov]$ ov] ) vegetation4 ,h5ce1 on a sea-cliff or esc>pm5t1 ! gre5 declivities betwe5 ! prom95t column> basalts usually m>k ! place ( su* less durable b&s4 ,exce$+ly slag-l lavas are to be se5 among ! amygdaloids1 imm$iately prec$$ & foll[$ by b$s ( compact black basalt ) few or no vesicles4 ,f ! mann] 9 :i* su* rocks yield to ! wea!r1 !y (t5 assume a s+ul>ly deceptive resemblance to agglom]ates4 ,"o ( ! be/ examples ( ?is resemblance :i* h come "u my notice is t ( ! rock on :i* /&s ,dunluce ,ca/le1 on ! nor? coa/ ( ,antrim4 ,huge r\nd$ blocks ( a h>d] consi/5cy ?an ! re/ ( ! rock project f ! surface ( ! cliffs1 l ! bombs ( a true volcanic agglom]ate1 :ile ! matrix 9 :i* !y are wrapp$ has decay$ f ar\nd !m4 ,b an exam9ation ( ?is matrix w soon conv9ce ! obs]v] t x is /rongly amygdaloidal1 & t ! app>5t bombs are only h>d] & less cellul> portions ( x4 ,! contra/ betwe5 ! wea!r+ ( ! two p>ts ( ! rocks seems to h aris5 f an orig9al v>iety 9 ! relative abundance ( /eam-cavities4 ,! orig9 ( su* nodul> or pill[-l blocks has be5 already ref]r$ to at pp4 #bf & #aic4 ,ano!r s+ul> in/ance occurs at ! foot ( ! outli] ( ,fionn ,*ro 7,fig4 #cfj71 9 ! isl& ( ,rum4 ,a conspicu\s b& und]ly+ ! basalts !re might readily be tak5 = a basalt-conglom]ate4 ,b 9 ?is case1 also1 ! app>5t matrix is f\nd to be amygdaloidal1 & ! r\nd$ blocks are really amygdales1 sometimes a foot 9 l5g?1 fill$ or l9$ ) qu>tz1 *alc$ony1 c4 ,a some:at diff]5t /ructure1 9 :i*1 h[ev]1 ! appe>ance ( volcanic breccia or agglom]ate due to explosion f a v5t is simulat$1 may be allud$ to "h4 ,! be/ in/ance :i* ,i h obs]v$ ( x occurs at ! s\? end ( ,lo*-na-,mna1 9 ! isl& ( ,eigg1 )9 a basalt :i* is rem>kable = a /reaky fl[-/ructure4 ,on ! wea!r$ faces ! /reaky lay]s may be obs]v$ to h be5 brok5 up1 & _! disconnect$ fragm5ts h be5 involv$ 9 ord9>y basalt :]e9 ?is fl[-/ructure is n develop$1 :ile l>ge blocks & irregul> masses are wrapp$ r\nd 9 a m decompos+ matrix4 ,!re c be no d\bt t 9 su* cases we see ! effects ( ! disruption ( *ill$ cru/s1 & ! entanglem5t ( ! brok5 pieces 9 ! /ill fluid lava4 ,x is a common belief t ! fill+ 9 ( ! /eam-cavities has tak5 place long subsequ5t to ! volcanic p]iod1 by ! sl[ p]colation ( meteoric wat] ?r\gh ! rock4 ,i believe1 h[ev]1 t at lea/ 9 "s cases1 if n 9 all1 ! conv]sion ( ! vesicul> lavas into amygdaloids 0 effect$ dur+ ! volcanic p]iod4 ,?us x c be %[n t ! basalts :i* h be5 disrupt$ by ! gabbros & granophyres 7 already amygdaloids be=e ^! basic intrusions di/urb$ !m1 = ! k]nels ( calcite1 zeolite1 etc41 h %>$ 9 ! g5]al metamorphism induc$ 9 ! enclos+ rock4 ,aga91 ! blocks ( amygdaloid conta9$ 9 ! agglom]ates ( ! volcanic s]ies are 9 e respect l ! amygdaloidal lavas ( ! plateaux4 ,x w\ld ?us seem t ! infill+ ( ! cavities ) m9]al secretions 0 n m]ely a long secul> process ( infiltration f ! cool atmosph]e1 b 0 m rapidly complet$ by ! op]ation ( w>m] wat]1 ei!r suppli$ f volcanic s\rces or heat$ by ! /ill high temp]ature ( ! cellul> lavas into :i* x desc5d$ f ! surface4#bbc ,footnote #bbc3 ,pr(essor ,j4 ,d4 ,dana1 orig9ally an advocate ( infiltration f above1 subsequ5tly support$ ! view t ! k]nels ( amygdaloids 7 fill$ 9 by ! action ( moi/ure )9 ! rocks dur+ ! "t ( cool+4--,am]4 ,j\rn4 ,sci4 s]4 #c1 vol4 xx4 7#ahhj71 p4 #cca4 ,messrs4 ,h>k] & ,m>r h demon/rat$ t ! ,l[] ,silurian vesicul> lavas ( ! ,lake di/rict _h already become amygdaloids be=e ! uprise ( ! ,%ap granite4--,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlix4 7#ahic74 #d?4 ,b&$ or /rati=m lavas1 consi/+ ( successive p>allel lay]s or b&s :i* wea!r into project+ ribs & flut+s4 ,! deceptive resemblance to s$im5t>y rocks ?us produc$ has no d\bt frequ5tly l$ to ^! lavas be+ mi/ak5 = tuffs4 ,z ,i h rec5tly f\nd !m to be mu* m pl5tiful ?an ,i _h suppos$1 a m detail$ description ( !m seems to be requir$4 ,! b&$ "* arises f m>k$ di/9ctions 9 ! texture ( diff]5t lay]s ( a lava-%eet4 ,9 "s cases 7a7 ^! di/9ctions arise f diff]5ces 9 ! size ( ! cry/als or 9 ! disposition ( ! compon5t m9]als ( ! rock2 9 o!rs 7b7 f ! v>y+ numb] & size ( ! vesicles1 :i* may be l>ge or abundantly cr[d$ toge!r 9 "s lay]s1 & small or only sp>sely develop$ 9 o!rs4 ,! /ructure ?us po9ts to orig9al conditions ( ! lava at ! "t ( its emission & may be reg>d$ z1 to "s ext5t1 a k9d ( fl[-/ructure on a l>ge scale4 7a7 ,:]e ! b&+ is due to diff]5ces ( cry/all9e texture1 ! con/itu5t felsp>s1 augites1 & iron-ores may be se5 ev5 ) ! nak$ eye z well-def9$ m9]als along ! prom95t surfaces ( ! h>d] ribs1 :ile ! broad] int]v5+ flut+s ( f9] mat]ial %[ ! same m9]als 9 m9ut] =ms4 ,! alt]nat+ lay]s ( co>s] & f9] cry/allization lie1 on ! :ole1 p>allel ) ! upp] & "u surfaces ( ! %eets 9 :i* !y occur4 ,b !y likewise undulate l ! /reaky l9es 9 ord9>y fl[-/ructure4 ,b&$ /ructure ( ?is type may be se5 well develop$ 9 ! l[] p>ts ( ! basalt-plateaux ?r\gh\t ! ,inn] ,hebrides & ! ,f>oe ,isl&s4 ,a specim5 tak5 f ! we/ end ( ! isl& ( ,s&ay1 ne> ,canna1 :i* %[$ ! /ructure by a conspicu\s p>allel flut+ on wea!r$ surfaces1 0 slic$ = microscopical exam9ation4 ,mr4 ,h>k] has be5 k9d en\gh to supply me ) ! foll[+ obs]vations reg>d+ ?is slice3-- ,9 ! slice #fffjbbd ! b&+ becomes less conspicu\s "u ! microscope4 ,! rock is ( basaltic composition1 &1 ) ref]5ce to its micro-/ructure1 might be /yl$ a f9e-gra9$ oliv9e-diabase or oliv9e-dol]ite 9 "s p>ts ( ! slice1 an oliv9e-basalt 9 o!rs4 ,x consi/s ( abundant gra9s ( oliv9e1 imp]fect octah$ra & %apeless granules ( magnetite1 little simple or tw9n$ prisms ( labradorite1 & a pale br[n augite4 ,! la/-nam$ m9]al is always ! late/ product ( consolidation1 b x v>ies 9 habit1 be+ sometimes 9 ophitic pat*es m\ld$ ^u or enclos+ ! o!r m9]als1 sometimes 9 small granules occupy+ ! int]/ices betwe5 ! felsp>s & o!r cry/als4 ,! ophitic habit pr$om9ates 9 ! slice1 :ile ! granulitic comes 9 especially along c]ta9 b&s4 ,if ! =m] be tak5 z indicative ( tranquil conditions1 ! latt] ( a c]ta9 am\nt ( movem5t 9 ! rock dur+ ! late/ /ages ( its consolidation1 ! b&+1 ?\gh n /rictly a fl[-/ructure1 may be ascrib$ 9 "s degree to a fl[+ movem5t ( ! ne>ly solidifi$ rock4 ,!re is1 h[ev]1 m ?an ?is m]ely /ructural diff]5ce betwe5 ! sev]al b&s4 ,!y diff] to "s ext5t 9 ! relative proportions ( ! m9]als1 especially ( oliv9e & augite2 :i* po9ts to a consid]able fl[+ movem5t at an e>ly /age 9 a magma :i* 0 initially n homog5e\s4 ,footnote #bbd3 ,! figures )9 squ>e brackets ?r\gh\t ! foll[+ pages ref] to ! numb]s ( ! microscopic slides 9 ! ,geological ,survey collection1 :]e ,i h deposit$ all ^? prep>$ f my specim5s4 7b7 ,:]e ! b&+ arises f ! di/ribution ( ! vesicles1 some:at simil> wea!r$ surfaces are produc$4 ,9 "s in/ances1 :ile ! basalt is ?r\gh\t f9ely cellul>1 int]pos$ b&s ( h>d]1 r f9]-gra9$ & less ?or\ghly vesicul> "* s]ve to give ! /ratifi$ appe>ance4 ,in/ances may be obs]v$ :]e ! vesicles h be5 cr[d$ toge!r 9 c]ta9 b&s1 :i* consequ5tly wea!r out diff]5tly f ! lay]s above & bel[ !m4 ,an excell5t illu/ration ( ?is arrangem5t occurs 9 ! l[e/ lava b "o ( ! l>ge/ ( ! ?ree picturesque /acks kn[n z ,macleod's ,maid5s on ! we/ coa/ ( ,skye 7,figs4 #bfj1 #bhc1 #bhd & #bhg74 ,?is lava is ?or\ghly amygdaloidal1 b ! vesicles are specially cr[d$ toge!r 9 c]ta9 p>allel b&s f an in* to ?ree or f\r in*es ?ick4 ,"s ( ^! lay]s lie close to ea* o!r1 :ile else:]e !re may be a b& ( m close-gra9$1 less vesicul> mat]ial betwe5 !m4 ,b ! mo/ s+ul> feature ( ! rock is to be se5 9 ! %ape & position ( ! vesicles t are cr[d$ toge!r 9 ! cellul> b&s4 ,in/ead ( be+ drawn out into flatt5$ =ms 9 ! g5]al direction ( b&+1 !y are plac$ toge!r at high angles4 ,ea* lay] rema9s p>allel to ! g5]al b$d+1 b its vesicles are /eeply incl9$ 9 "o direction1 :i* 0 d\btless t ( ! fl[ ( ! /ill unconsolidat$ lava4#bbe ,wea!r+ along ^! b&s1 ! lava might easily be mi/ak5 at a little di/ance = a tuff or o!r /ratifi$ int]calation4 ,footnote #bbe3 ,?is elongation ( vesicles1 m or less p]p5dicul> to ! g5]al b$d+1 may be notic$ sometimes ev5 9 sills1 z w be %[n 9 a lat] ,*apt]4 ,illu/ration3 ,fig4 #bfj4--;,b&$ amygdaloidal basalt %[+ lay]s ( elongat$ & /eeply incl9$ vesicles1 ,macleod's ,maid5s1 ,skye4 ,b&$ lavas possess+ ! *>act]s n[ describ$ are ( frequ5t occurr5ce among ! ,inn] ,hebrides4 ,_m /rik+ examples ( !m may be se5 along ! we/ coa/ ( ,skye4 ,/ill m abundant 9 ,f>oe1 !y =m "o ( ! mo/ conspicu\s features 9 ! geology ( t gr\p ( isl&s4 ,along ! :ole ( its we/]n seabo>d1 on isl& aft] isl&1 !y are p>ticul>ly prom95t 9 ! l[] p>ts ( ! precipices1 :ile ! upp] p>ts consi/ l>gely ( amorph\s or prismatic %eets4 ,s mu* d !y resemble /ratifi$ rocks t x 0 n until ,i _h l&$ at v>i\s po9ts t ,i c\ld satisfy myself t !y are really b&$ lavas4#bbf ,footnote #bbf3 ,= rec5t contributions to ! ,geology ( ! ,f>oe ,isl&s1 see ,pr(4 ,james ,geikie1 ,trans4 ,roy4 ,soc4 ,ed94 vol4 xxx4 7#ahhj71 p4 #bag1 :]e ! b&+ ( ! basalts is notic$2 ,pr(4 ,a4 ,hell&1 ,dansk4 ,geografisk4 ,tidskr4 7#ahha72 ,r4 ,bron1 ,notes p\r s]vir l'tude de la ,gologie de l',isl&e et des ,isles ,fa]oe 7#ahhd72 ,mr4 ,j4 ,lomas1 ,proc4 ,geol4 ,soc4 ,liv]pool1 vol4 vii4 7#ahie71 p4 #bib4 ,v>i\s writ]s h treat$ ( ! petrography ( ,f>oe1 p>ticul>ly ,a4 ,osann1 ,neues ,jahrb4 7#ahhd71 vol4 i4 p4 #de1 & ,m4 ,bron 9 ! volume "h cit$4 #e?4 ,ord9>y fl[-/ructure1 save 9 ^! b&$ lavas1 is r r>e among ! plateaux4 ,x may1 h[ev]1 be occasionally obs]v$1 :]e !re is no di/9ct b&+4 ,on a wea!r$ surface x appe>s 9 f9e1 widely p>allel /reaks1 :i* are sometimes wavy1 puck]$ & brok5 up1 z 9 rhyolites & felsites1 :ile ! porphyritic felsp>s are arrang$ ) _! long axes 9 ! direction ( fl[4 ,a good example ( ^! *>act]s may be se5 on ! summit ( ! ,dn ,c--! rem>kable truncat$ cone :i* =ms ! highe/ po9t on ! ,isl& ( ,raasay4 ,! rock is a black oliv9e-basalt1 p>tly amygdaloidal1 ) zeolites fill+ up ! cavities1 & its fl[-l9es are prom95t on ! wea!r$ faces :]e !y lie p>allel to ! g5]al b$d+ ( ! lavas4 ,ano!r illu/ration may be obs]v$ 9 ! basalt already cit$ f ,lo*-na-,mna1 9 ! isl& ( ,eigg1 :]e ! rock pres5ts 9 places a rem>kable /reaky /ructure :i*1 ?\gh h>dly visible on a fre% fracture1 reveals itself on a wea!r$ face 9 ?9 ne>ly p>allel ribs co9cid5t 9 direction ) ! upp] & "u surfaces ( ! mass4 ,great v>iety is to be f\nd 9 ! ?ickness ( diff]5t %eets ( lava 9 ! plateaux4 ,"s ( !m are n m ?an #f or #h feet2 o!rs rea* to #hj or #ajj feet1 & sometimes1 ?\gh r>ely1 to ev5 great] dim5sions4 ,9 ,antrim1 ! av]age ?ickness ( ! fl[s is probably f #ae to #bj feet4#bbg ,9 ! f9e coa/-sections at ! ,giant's ,causeway1 h[ev]1 "s b&s may be se5 f> 9 excess ( t measurem5t4 ,! b$ t =ms ! ,causeway1 = in/ance1 is ab\t #fj or #gj feet ?ick1 & seems to become ev5 ?ick] fur!r ea/4 ,along ! great esc>pm5t1 #gjj feet high1 :i* rises f ! %ores ( ,gribon1 on ! we/ coa/ ( ,mull1 !re are tw5ty sep>ate b$s1 :i* give an av]age ( #ce feet = ! ?ickness ( ea* fl[4 ,on ! great range ( sea-precipices along ! we/ coa/ ( ,skye1 :i* pres5t ! mo/ /up5d\s section ( ! basalts any:]e to be se5 )9 ! limits ( ! ,briti% ,isl&s1 ! av]age ?ickness ( ! b$s c be conv5i5tly measur$4 ,at ! ,talisk] cliffs "s ( ! fl[s are n m ?an #f or #h feet2 o!rs are #cj or #dj feet4 ,! *ief precipice1 #ieg feet high 7,fig4 #bhf71 conta9s at lea/ #ah or #bj sep>ate lava-%eets1 :i* ?us av]age ( f #dg to #ec feet 9 ?ickness4 ,9 ! cliffs t =m ! seaw>d m>g9 ( ! tablel& ( ,macleod's ,tables 7,fig4 #bhc7 f\rte5 successive b$s ( basalt c be c\nt$ 9 a v]tical section ( #djj feet1 :i* is equal to an av]age ?ickness ( ab\t #bh feet4 ,b "s ( ! basalts are only ab\t #f feet ?ick1 :ile o!rs are #ej or #fj4 ,! ,hoe ( ,duir9i%1 #gei feet high1 is compos$ ( ab\t sixte5 di/9ct b$s1 :i* ?us h a mean ?ickness ( #df feet4 ,! av]age ?ickness ( ! successive fl[s on ,dunvegan ,head1 :i* is #ajjj feet high & conta9s at lea/ tw5ty-five sep>ate %eets1 is ab\t #dj feet4 ,/ill fur!r nor?1 ! cliffs1 #hjj feet high1 comprise sixte5 successive fl[s1 :i* h ?us an av]age ( #ej feet ea*4 ,among ! ,f>oe ,isl&s ! av]age ?ickness ( ! basalt-%eets seems to be ne>ly ! same z 9 ,brita94 ,?us 9 ! magnific5t ranges ( precipices ( ,kals1 ,kun & ,bor1 =ty or m %eets may be c\nt$ 9 ! va/ walls ( rock "s #bjjj feet high1 giv+ a mean ( ab\t #ej feet4 ,footnote #bbg3 ,see ,explanation ( ,%eet #bj1 ,geol4 ,survey1 ,irel&1 p4 #aa4 ,ea* b$ appe>s1 on a cursory inspection1 to reta9 its av]age ?ickness1 & to be cont9u\s = a long di/ance4 ,b ,i believe t ?is p]si/5ce is 9 great measure deceptive4 ,we c seldom foll[ ! same b$ ) absolutely unbrok5 cont9uity = m ?an a mile or two4 ,ev5 9 ! mo/ fav\rable conditions1 su* z are af=d$ by a b>e sea-cliff on :i* e %eet c be se51 !re occur small faults1 gullies :]e ! rocks are = ! "t conceal$1 slopes ( debris1 & o!r failures ( cont9uity2 :ile ! rocks are g5]ally s l ea* o!r1 t on ! fur!r side ( any su* int]ruption1 x is n always possible to make sure t we are /ill trac+ ! same b$ ( basalt :i* we may h be5 previ\sly foll[+4 ,on ! o!r h&1 a c>eful exam9ation ( "o ( ^! great natural sections w usually supply u ) pro(s t1 :ile ! b$d$ "* may cont9ue well m>k$1 ! individual %eets die out1 & are replac$ by o!rs ( simil> "*4 ,cases may n infrequ5tly be obs]v$ :]e ! basalt ( "o %eet abruptly w$ges out1 & is replac$ by t ( ano!r4 ,:]e bo? are ( ! same v>iety ( rock1 x requires close inspection to make out ! diff]5ce betwe5 !m2 b :]e "o is a gre51 dull1 e>?y1 amorph\s amygdaloid1 & ! o!r is a compact1 black1 prismatic basalt1 ! contra/ betwe5 ! two b$s c be recogniz$ f a di/ance 7,fig4 #bfa74 ,9 ! basaltic cliffs ( ! we/ coa/ ( ,skye1 ! really l5ticul> "* ( ! fl[s c be well se54 ,i may especially cite ! great headl& s\? ( ,talisk] ,bay1 already ref]r$ to1 :]e1 9 ! pile ( ne>ly horizontal %eets1 two b$s may be se5 to die out1 "o t[>ds ! nor?1 ! o!r t[>ds ! s\?4 ,fur!r nor?1 9 ! cliff ( ! ,hoe ( ,duir9i%1 a simil> /ructure pres5ts itself4 ,along ! coa/-cliffs ( ,mull1 ,morv5 & ,canna ! same fact is cle>ly display$4 ,?us on ! we/ side ( ! ,s\nd ( ,mull ! slopes above ,fi%ni% ,bay %[ a gr\p ( basalts1 :i* die out s\?w>d1 & are ov]lapp$ by a y\ng] gr\p t has be5 p\r$ ov] _! ends4 ,su* sections are be/ se5 9 ! ev5+1 :5 ! grass-cov]$ lavas %[ _! successive %eets by _! respective %ad[s1 _! individuality be+ lo/ 9 ! full light ( day4 ,a m /rik+ example occurs beyond ! we/ end ( ,gl5 ,m 9 ,mull1 :]e "o s]ies ( basalts has be5 tilt$ up1 probably dur+ "s volcanic episode1 & has _h a y\ng] s]ies bank$ up aga9/ its edges4 ,illu/ration3 ,fig4 #bfa4--,t]m9ation ( ,basalt-b$s1 ,c>saig1 ,mull4 ,9 ,antrim also1 rem>kable evid5ce is pres5t$ ( ! rapid att5uation n ( s+le b$s only1 b ( a :ole s]ies ( basalts4 ,?us1 at ,ballyca/le1 ! gr\p ( lavas kn[n z ! ,l[] ,basalts1 :i* und]lie ! well-kn[n horizon ( iron-ore1 are at lea/ #cej feet ?ick4 ,b1 z we trace !m we/w>ds1 b$ aft] b$ ?9s out until1 a little to ! we/ ( ,ball9toy1 9 a di/ance ( only ab\t #f miles1 ! :ole dep? ( ! gr\p has dim9i%$ to some:]e ab\t #dj feet4 ,a decrease ( m ?an #cjj feet 9 six miles or #ej feet p] mile po9ts to consid]able inequalities 9 ! accumulation ( ! lavas4 ,if ! next s]ies ( fl[s came f ano!r v5t & accumulat$ aga9/ su* a g5tle slope1 x w\ld be m>k$ by a slight uncon=mability4 ,/ructures ( ?is k9d are mu* r>] ?an we %\ld expect !m to be1 consid]+ ! great ext5t to :i* ! plateaux h be5 dissect$ & laid op5 9 cliff-sections4 ,! basalt-plateau ( ! ,f>oe ,isl&s exhibits ) rem>kable cle>ness ! l5ticul> "* ( ! basalt-%eets1 & a numb] ( examples w be cit$ 9 ! description ( t region to be giv5 9 ,*apt] xxxix4 ,9 ^! nor!rn climes vegetation spreads less widely ov] rock & slope ?an x does 9 ! mild] air ( ! ,inn] ,hebrides4 ,h5ce ! esc>pm5ts sweep 9 precipices ( almo/ b>e rock f ! level ( ! sea up to ! s]rat$ cre/s ( ! isl&s1 "s #bjjj feet 9 height4 ,ea* individual b$ ( basalt c ?us be foll[$ cont9u\sly along ! fjords1 & its v>iation or disappe>ance c be readily obs]v$4 ,coa/+ along ^! va/ natural sections1 we readily p]ceive t1 z among ! ,we/]n ,isles1 ! successive %eets ( basalt h proce$$ f no "o common c5tre ( eruption4 ,!y die out n[ t[>ds "o qu>t]1 n[ t[>ds ano!r1 yet ev]y:]e reta9 ! univ]sal regul>ity & g5tle incl9ations ( ! :ole volcanic s]ies4 ii4 ,,fragm5tal ,,rocks ,:ile ! plateaux are built up ma9ly ( successive fl[s ( basaltic lavas1 !y include v>i\s int]calations ( fragm5tal mat]ials1 :i*1 ?\gh ( trifl+ ?ickness1 are ( great int]e/ & importance 9 reg>d to ! light :i* !y ca/ on ! hi/ory ( ! diff]5t regions dur+ ! volcanic p]iod4 ,i %all enum]ate ! *ief v>ieties ( ^! rocks "h1 & aft]w>ds give full] details reg>d+ _! /ratigraphical relations & mode ( occurr5ce 9 connection ) ! succession ( b$s 9 ea* ( ! plateaux4 7a7 ,volcanic ,agglom]ates4--,9 ! tumultu\s un/ratifi$ masses ( fragm5t>y mat]ials :i* fill eruptive v5ts 9 & ar\nd ! plateaux1 ! /ones1 :i* v>y 9 size up to blocks sev]al feet 9 diamet]1 consi/ = ! mo/ "p ( basalts1 (t5 highly slaggy & scoriace\s4 ,!y include also fragm5ts ( diff]5t acid eruptive rocks 7g5]ally felsitic or rhyolitic 9 texture71 ) pieces ( ! non-volcanic rocks ?r\gh :i* ! volcanic pipes h be5 drill$4 ,! pa/e is granul>1 dirty-gre5 or br[n 9 col\r1 & seems g5]ally to consi/ *iefly ( comm9ut$ basalt4 ,z 9 ! ,c>bonif]\s & ,p]mian necks1 ! ,t]ti>y agglom]ates conta9 abundant detritus ( a basic m9utely cellul> pumice4 7b7 ,volcanic ,conglom]ates & ,breccias 9 b$s int]calat$ betwe5 ! fl[s ( ,basalt4--,^! are ( at lea/ ?ree k9ds4 7a7 ,basalt-conglom]ates1 compos$ ma9ly ( r\nd$ & subangul> blocks ( basalt 7or alli$ basic lava71 sometimes a y>d or m 9 diamet]1 n unfrequ5tly 9 ! =m ( pieces ( r\gh slag or ev5 ( true bombs1 imb$d$ 9 a granul> matrix ( comm9ut$ basalt-debris4 ,9 "s cases1 ! /ones =m by f> ! mo/ abundant con/itu5ts ( ! rock1 :i* !n resembles "s ( ! co>se agglom]ates j describ$4 ,p]haps ! mo/ rem>kable accumulations ( ?is k9d are ^? int]calat$ among ! basalts 9 ! isl&s ( ,canna & ,s&ay1 ( :i* a detail$ acc\nt w be giv5 9 ,*apt] xxxviii4 ,^! conglom]ates1 besides _! volcanic mat]ials1 conta9 r\nd$ blocks ( ,torridon s&/one & o!r rocks1 :i* mu/ h be5 c>ri$ f ! ea/ by "s tol]ably p[]ful riv] t fl[$ across ! basalt-pla9s dur+ ! volcanic p]iod4 ,aga91 on ! ea/ side ( ,mull1 ! slaggy basalts ( ,be9n ,*reaga* ,mhor are occasionally sep>at$ by volcanic conglom]ates4 ,z a rule1 h[ev]1 su* int]calations are seldom m ?an a few feet or y>ds 9 ?ickness4 ,_! co>s5ess & repetition on successive horizons indicate t !y probably accumulat$ 9 ! ne> neighb\rhood ( "o or m small v5ts1 f :i* dis*>ges ( fragm5t>y mat]ials took place at ! beg9n+ or at ! close ( an outfl[ ( lava1 & t ! /ones 7 sometimes swept away f ! cones & roll$ ab\t by /reams be=e be+ buri$ "u ! succe$+ lava-%eets4 ,m commonly ! dirty-gre5 or d>k-br[n granul> matrix exce$s 9 bulk ! /ones emb$d$ 9 x4 ,x has obvi\sly be5 d]iv$ ma9ly f ! trituration ( already cool$ basalt--masses1 & probably also f explosions ( ! /ill molt5 rock 9 ! v5ts4 ,a /rik+ illu/ration ( ?is type ( rock may be se5 on ! s\? side ( ,portree ,h>b\r1 :]e a mass ( d>k-gre5 basalt-conglom]ate1 ) a coaly lay] above x1 lies ne> ! base ( ! b$d$ basalts1 & atta9s at "o "p ( its c\rse a ?ickness ( ab\t #bjj feet4 ,?is rock w be aga9 ref]r$ to 9 connection ) ! v5t f :i* its mat]ials 7 probably d]iv$4 ,z 9 ! case ( ! agglom]ates ( ! v5ts1 pieces ( old] acid lavas1 & /ill m ( ! non-volcanic rocks t und]lie ! plateaux1 are f\nd 9 ! b$d$ conglom]ates & breccias4 ,9 ,antrim & ,mull1 = in/ance1 fragm5ts ( fl9t & *alk are ( common occurr5ce4 ,a *>act]i/ic example ( ?is k9d ( rock =ms ! plat=m ( ! column> b$ out ( :i* ,f+al's ,cave1 ,/affa1 has be5 excavat$ 7,fig4 #bff;a74 7,greek3 beta7 ,felsitic ,breccia4--,?is v>iety1 ?\gh ( r>e occurr5ce1 is to be se5 9 a numb] ( localities 9 ! isl& ( ,mull4 ,x is compos$ 9 great measure ( angul> fragm5ts ( close-gra9$ fl9ty felsitic or rhyolitic rocks1 sometimes %[+ beautiful fl[-/ructure1 toge!r ) pieces ( qu>tzite & amygdaloidal basalt1 ! dull dirty-gre5 matrix appe>+ to be made up *iefly ( basalt-du/4 7,greek3 gamma7 ,rhyolitic ,conglom]ate4--,betwe5 ! upp] & l[] gr\p ( basalts 9 ! ,antrim plateau !re occur b&s ( a pale fawn-col\r$ conglom]ate l>gely made up ( m or less r\nd$ fragm5ts ( rhyolite1 l "s ( ! v>ieties ( ! rock :i* occur 9 place on ! plateau4 ,! rhyolitic debris is (t5 mix$ ) pebbles ( basalt4 ,sometimes x becomes s f9e z to pass into pale clays4 7,greek3 delta7 ,breccias ( non-volcanic mat]ials4--,^!1 ! mo/ exceptional ( all ! fragm5t>y int]calations 9 ! plateaux1 consi/ almo/ :olly ( angul> blocks ( rocks :i* are kn[n to und]lie ! basalts1 b ) a v>iable admixture ( basalt fragm5ts4 ,!y are due to volcanic explosions :i* %att]$ ! subjac5t old] cru/ ( rocks1 & dis*>g$ fragm5ts ( ^! f ! v5ts or all[$ !m to be borne upw>ds on an asc5d+ column ( lava4 ,pieces ( ! non-volcanic plat=m are ( common occurr5ce among ! fragm5t>y accumulations1 especially 9 ! l[] p>ts ( ! plateaux basalts4 ,b ,i h nev] se5 s rem>kable an example ( a breccia ( ?is k9d z t :i* occurs ne> ! summit ( ,sgurr ,de>g1 9 ! s\?-ea/ ( ,mull4 ,! b$d$ basalt encloses a l5ticul> b& ( exce$+ly co>se breccia1 consi/+ ma9ly ( angul> pieces ( qu>tzite1 ) fragm5ts ( amygdaloidal basalt4 ,9 ! mid/ ( ! breccia lies a huge mass or cake ( erupt$ mica-s*i/1 at lea/ #ajj y>ds long by #cj y>ds wide1 z measur$ across ! /rike up ! slope ( ! hill4 ,to ! we/1 ow+ to ! ?9n+ out ( ! breccia1 ?is piece ( s*i/ comes to lie betwe5 two b$s ( basalt4 ,a little high] up1 o!r small] b /ill l>ge blocks ( simil> s*i/ are involv$ 9 ! basalt1 z %[n 9 ,fig4 #bfb4 ,z ! huge cake ( mica-s*i/ plunges into ! hill1 its :ole dim5sions _c be se52 b !re are visible1 at lea/1 #ae1jjj cubic y>ds1 :i* mu/ weigh m ?an #cj1jjj tons4 ,blocks ( qu>tzite ( less dim5sions occur 9 ! basalts on ,lo* ,spelve1 9 ! same di/rict4 ,!re c be no d\bt1 ,i ?9k1 t ^! enorm\s fragm5ts 7 torn (f f ! und]ly+ cry/all9e s*i/s :i* =m ! framework ( ! ,we/]n ,highl&s1 & 7 float$ upw>d 9 an asc5d+ fl[ ( molt5 basalt4 ,_h ! l>ge/ mass occurr$ at or ne> ! base ( ! volcanic s]ies1 its size & position w\ld h be5 less rem>kable4 ,b x lies m ?an #bjjj feet up 9 ! basalts1 & h5ce mu/ h be5 borne upw>d = m ?an t height4 ,a simil> b less /rik+ breccia occurs on ! s\? coa/ ( ! same isl&1 ne> ,c>saig1 made up *iefly ( pieces ( qu>tzite & qu>tz4#bbh ,footnote #bbh3 ,?is is notic$ by ,mr4 ,/>kie ,g>dn]1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xliii4 7#ahhg71 p4 #bhc1 note4 ,"s rem>kable agglom]ates1 ne> ,=khill1 ,armagh1 probably belong+ to ! ,t]ti>y volcanic s]ies1 w be describ$ 9 ! acc\nt ( ! ,iri% acid rocks 7,*apt] xlvii474 ,!y consi/ entirely ( non-volcanic /ones & du/ & are traceable = "s miles along ! l9e ( a fissure4 ,:]e !y h be5 dis*>g$ ?r\gh granite !y consi/ entirely ( ! detritus ( t rock1 b :]e !y h be5 erupt$ 9 ! ,silurian area !y consi/ ( fragm5ts ( grits & %ales4 ,!y seem to h be5 produc$ by ri=m dis*>ges1 )\t ! uprise ( any volcanic magma1 ?\gh ev5tually &esite & rhyolite asc5d$ ! fissure & became full ( granitic & ,silurian fragm5ts4 ,"s rem>kable necks fill$ almo/ entirely ) fragm5ts ( ,torridon ,s&/one h be5 obs]v$ 9 ! we/ ( ,applecross1 ,ross-%ire1 & "s curi\s plug-l masses ( breccia1 also made up ( fragm5ts ( ,torridonian /rata1 occur 9 ! isl& ( ,raasay4 ,^! examples w be m p>ticul>ly describ$ on lat] pages 7pp4 #bib1 #bic74 7c7 ,tuffs4--,! tuffs int]calat$ 9 ! basalt-plateaux g5]ally consi/ ess5tially ( basic mat]ials1 d]iv$ f ! de/ruction ( diff]5t v>ieties ( basalts1 ?\gh also conta9+ occasional fragm5ts ( old] felsitic rocks1 z well z pieces ( *alk1 fl9t1 qu>tz1 & o!r non-volcanic mat]ials4 ,!y are g5]ally dull1 dirty-gre5 9 col\r1 b become r$1 lilac1 br[n1 & yell[1 accord+ to ! am\nt & /ate ( comb9ation & oxidation ( _! f]rug9\s con/itu5ts4 ,!y usually conta9 abundant fragm5ts ( amygdaloidal & o!r basalts4 ,z a rule1 !y are di/9ctly /ratifi$1 & occur 9 b&s f a few in*es to #ej feet or m 9 ?ickness4 ,! matrix be+ s(t & mu* decompos$1 ^! b&s crumble away "u ! action ( ! wea!r1 & contribute to ! abruptness ( ! basalt-esc>pm5ts t ov]lie !m4 ,illu/ration3 ,fig4 #bfb4--;,breccia & ,blocks ( mica-s*i/1 qu>tzite1 etc41 ly+ betwe5 b$d$ ,basalts1 ,isle ( ,mull4 a a1 ,b$d$ basalts2 b1 ,breccia2 d1 ,basic dyke4 ,9 ! gr\p ( /rata betwe5 ! two s]ies ( basalts 9 ,antrim1 "s ( ! tuffs consi/ *iefly ( rhyolitic detritus1 bo? glassy & li?oid4 ,:]e ! tuffs become f9e-gra9$ & free f imb$d$ /ones1 !y pass into v>i\sly-col\r$ clays4 ,among ^! are ! bauxite & li?om>ge ( ,antrim1 probably d]iv$ f pale rhyolitic tuffs & conglom]ates 7p4 #bjd74 ,associat$ ) ^! deposits 9 ! same di/rict1 is a pisolitic hmatite1 :i* has be5 prov$ to occur ov] a consid]able area on ! same horizon4 ,_m ( ! clays are highly f]rug9\s4 ,! r$ /reaks t int]v5e betwe5 successive %eets ( basalt are ( ?is nature 7bole1 pl9?ite1 etc474 ,! s\rce ( ! iron-oxide is d\btless to be trac$ to ! decomposition ( ! basic lavas dur+ ! volcanic p]iod4 7d7 ,!re occur also grey & black clays & %ales1 ( ord9>y s$im5t>y mat]ials1 conta9+ leaves ( t]re/rial plants 7leaf-b$s71 ) occasional w+-cases ( beetles1 sometimes associat$ ) impure lime/ones1 b m frequ5tly ) s&/ones & indurat$ gravels or conglom]ates conta9+ pieces ( fossil wood4 ,^! int]calat$ b&s und\bt$ly indicate ! action ( runn+ wat]1 sometimes ev5 ( riv]-floods1 & ! accumulation ( s$im5t 9 holl[s ( ! expos$ fl[s ( basalt at int]vals dur+ ! pil+ up ( ! successive lava-%eets t =m ! plateaux4 ,! alt]nation ( fluviatile gravels ) volcanic tuffs1 fluviatile conglom]ates1 & lava-/reams1 is admirably display$ 9 ! isl& ( ,canna1 z w be n>rat$ 9 detail 9 ,*apt] xxxviii4 ,! vegetable matt] has 9 "s places ga!r$ into l5ticul> seams ( lignite1 & ev5 occasionally ( black glossy coal4 ,amb] also has be5 f\nd 9 ! lignite4 ,:]e ! vegetation has be5 expos$ to ! action ( intrusive dykes or %eets1 x has sometimes pass$ into ! /ate ( graphite4 ,! rem>kable t]re/rial flora f\nd 9 ! leaf-b$s1 & 9 association ) ! lignites1 0 fir/ made kn[n by ! descriptions ( ,edw>d ,=bes already ref]r$ to1 & has subsequ5tly be5 /udi$ & describ$ by ,he]1 ,w4 ,h4 ,baily1 & ,mr4 ,/>kie ,g>dn]4#bbi ,x 0 reg>d$ by ,=bes z ( ,mioc5e age1 & ?is view has g5]ally be5 adopt$ by geologi/s4 ,mr4 ,/>kie ,g>dn]1 h[ev]1 cont5ds t x indicates a mu* wid] range ( geological "t4 ,he believes t a succession ( floras may be recognis$1 ! olde/ belong+ to an e>ly "p ( ! ,eoc5e p]iod4 ,t]re/rial plants1 x mu/ be admitt$1 are n always a reliable te/ ( geological age1 & ,i am n yet satisfi$ t 9 ?is in/ance !y af=d evid5ce ( su* a *ronological sequ5ce z ,mr4 ,g>dn] claims1 ?\gh ,i am conv9c$ t ! ,t]ti>y volcanic p]iod 0 long en\gh to h all[$ ( ! developm5t ( consid]able *anges 9 ! "* ( ! vegetation4 ,footnote #bbi3 ,on ?is subject consult ,duke ( ,argyll1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 vii4 7#ahea71 p4 #hi2 ,e4 ,=bes1 ,ibid4 p4 #ajc2 ,w4 ,h4 ,baily1 op4 cit4 xxv4 7#ahfi71 pp4 #afb1 #ceg2 ,brit4 ,assoc4 ,rep4 7#ahgi7 p4 #afb2 7#ahhj7 p4 #ajg2 7#ahha7 p4 #aea2 7#ahhd7 p4 #bji2 ,mr4 ,j4 ,/>kie ,g>dn]1 ,palontographical ,society1 vols4 xxxviii4 xxxix4 ,9 ! la/ ( ,mr4 ,baily's pap]s he notices t ! ,rev4 ,dr4 ,gra+] f\nd a portion ( a fi% 7,p]cid1 possibly ,lates74 ,! discov]y ( ! rema9s ( a fre%-wat] fi% is an important additional te/imony to ! t]re/rial conditions "u :i* ! lavas 7 erupt$4 ,! g5us ,lates n[ inhabits ! ,nile & ! ,ganges4 ,= ! purpose ( ! pres5t volume1 h[ev]1 ! precise /age 9 ! geological record1 :i* ?is flora indicates1 is ( less consequ5ce ?an ! broad fact t ! plants prove beyond all "q t ! basalts among :i* !y lie 7 erupt$ on l& dur+ ! old] "p ( ! long succession ( ,t]ti>y p]iods4 ,_! value 9 ?is respect _c be ov]e/imat$4 ,/ratigraphical evid5ce %[s t ! eruptions mu/ be lat] ?an ! ,upp] ,*alk2 b ! imb$d$ plants def9itely limit !m to ! e>li] half ( ,t]ti>y "t4 ,,*apt] ,,xxxvii ,,! ,,sev]al ,,basalt-,,plateaux ,,& ,,_! ,,geological ,,hi/ory1 ,,antrim1 ,,mull1 ,,morv5 ,,& ,,ardnamur*an ,!re are five di/ricts 9 ,nor?-we/]n ,europe :]e ! orig9al widespread ,t]ti>y lava-fields h be5 less ext5sively erod$ ?an else:]e1 or at lea/ :]e !y h surviv$ 9 l>g] & ?ick] masses4 ,:e!r or n ea* ( !m 0 an isolat$ area ( volcanic activity _c n[ be det]m9$4 ,_! sev]al outfl[s ( lava )9 ! area ( ! ,briti% ,isles may h unit$ into "o cont9u\s volcanic tract1 & _! pres5t isolation !re may be due entirely to subt]ranean movem5ts & d5udation4 ,!re is a c]ta9 conv5i5ce1 h[ev]1 9 treat+ ! di/ricts sep>ately4 ,!y are--#a4 ,antrim2 #b4 ,mull1 ,morv5 & ,ardnamur*an2 #c4 ,small ,isles2 #d4 ,skye2 #e4 ,! ,f>oe ,isl&s4 i4 ,,antrim#bcj ,footnote #bcj3 ,! basalts ( ,antrim are ! subject ( an abundant lit]ature4 ,i may ref] p>ticul>ly to ! pap]s ( ,b]g] & ,conybe>e 7,trans4 ,geol4 ,soc4 iii471 ! ,geological ,report ( ,portlock1 & ! ,explanations ( ! ,%eets ( ! ,geological ,survey ( ,irel&4 ,o!r pap]s w be aft]w>ds cit$4 ,! g5]al features ( ! ,antrim plateau are %[n on ,map ,,vii4 ,! l>ge/ ( ! basalt-plateaux ( ,brita9 is t :i* =ms s prom95t a feature 9 ! sc5]y & geology ( ! ,nor? ( ,irel&1 /ret*+ f ,l\gh ,foyle to ,belfa/ ,l\gh1 & f ,ra?l9 ,isl& to beyond ! s\!rn m>g9 ( ,l\gh ,neagh4 ,its area may be r\ghly comput$ at ab\t #bjjj squ>e miles4 ,b1 z its truncat$ /rata rise high along its bord]s1 & look f> ov] ! surr\nd+ l[ gr\nds1 x mu/ be reg>d$ z a m]e fragm5t ( ! orig9al volcanic pla94 ,x may be describ$ z an undulat+ tablel&1 :i* almo/ ev]y:]e t]m9ates 9 a range ( bold cliffs1 b :i*1 t[>ds ! c5tre & s\?1 s9ks g5tly into ! bas9 ( ,l\gh ,neagh4 ,! m>g9al l9e ( esc>pm5t1 h[ev]1 pres5ts consid]able irregul>ity bo? 9 height & =m1 besides be+ liable to frequ5t local int]ruptions4 ,x is highe/ on ! we/ side1 "o ( its cre/s rea*+ at ,mullaghmore1 9 ,c\nty ,londond]ry1 a height ( #ahbe feet4 ,x s9ks d[n into ! valley ( ! ,bann1 ea/ ( :i* x gradually asc5ds1 =m+ ! well-kn[n range ( cliffs f ! ,giant's ,causeway & ,b5gore ,head to ,ballyca/le4 ,x !n /rikes inl&1 & mak+ a wide curve 9 :i* x rea*es a height ( m ?an #acjj feet1 comes to ! sea aga9 at ,g>ron ,po9t4 ,f t headl& ! cliffs ( basalt =m a belt ( picturesque gr\nd s\?w>ds beyond ,belfa/1 int]rupt$ only by valleys t convey ! dra9age ( ! int]ior ( ! plateau to ! ,nor? ,*annel4 ,above ! valley ( ! ,lagan ! cre/ ( ! plateau rises to a height ( m ?an #aejj feet4 ,?r\gh\t mo/ ( its ext5t ! basalt-esc>pm5t re/s on ! :ite lime/one or ,*alk ( ,antrim1 b5ea? :i* lie s(t ,lias %ales & ,triassic m>ls4 ,"h & !re1 :]e ! sub/ratum ( ,*alk is ?91 ! action ( und]gr\nd wat] on ! crumbl+ %ales & m>ls bel[ x has giv5 rise to l&slips4 ,! slopes b5ea? ! base ( ! basalt are /rewn ) slipp$ masses ( t rock1 almo/ all ! way f ,cu%5dall to ,l>ne1 "s ( ! deta*$ portions be+ s l>ge z to be readily tak5 = p>ts ( ! unmov$ rock4 ,on ! we/ side also1 a gr\p ( huge l&slips cumb]s ! declivities b5ea? ! mural front ( ,b5ev5agh4 ,i h f\nd "s difficulty 9 ! attempt to asc]ta9 :at 0 ! probable =m ( surface ov] :i* ! volcanic rocks ( ?is plateau began to be p\r$ out4 ,! ,*alk s9ks bel[ ! sea-level on ! nor? coa/1 b1 9 ! outli] ( ,slieve ,gallion1 ?ree miles beyond ! we/]n base ( ! esc>pm5t1 x rises to a height ( #aejj feet above ! sea4 ,on ! ea/ side also1 x %[s rem>kable diff]5ces ( level4 ,?us1 bel[ ! ,:ite ,head at ! m\? ( ,belfa/ ,l\gh1 x passes "u ! sea-level1 b only #af miles to ! s\?1 :]e x crops out f "u ! basalt1 its surface is ab\t #ajjj feet above t level4 ,if ^! v>iations 9 height exi/$ at ! "t ( ! outp\r+ ( ! basalt1 ! surface ( ! gr\nd ov] :i* ! eruptions took place 0 s irregul> t "s hundr$s ( feet ( lava mu/ h accumulat$ be=e ! high] *alk hills 7 buri$ "u ! volcanic dis*>ges4 ,b x seems to me t mu* ( ?is inequality 9 ! height ( ! upp] surface ( ! ,*alk is to be attribut$ to unequal movem5ts s9ce ! volcanic p]iod1 :i* involv$ ! basalt 9 _! effects1 z well z ! plat=m ( ,*alk bel[ x4 ,_h ! pres5t undulations ( t plat=m be5 old] ?an ! volcanic dis*>ges1 x is obvi\s t upp] portions ( ! basalt-s]ies w\ld h ov]lapp$ l[]1 & w\ld h come to re/ directly on ! ,*alk4 ,b ?is arrangem5t1 s f> z ,i am aw>e1 nev] occurs1 except on a trifl+ scale4 ,:]ev] ! ,*alk appe>s1 x is cov]$ by %eets ( ! l[] & n ( ! upp] ( ! two gr\ps into :i* ! ,antrim basalts are divisible4 ,we h actual pro( ( consid]able t]re/rial di/urbance1 subsequ5t to ! date ( ! =mation ( ! volcanic plateau4 ,?us1 ne> ,ballyca/le1 a fault lets d[n ! basalt & its ,*alk plat=m aga9/ ! cry/all9e s*i/s ( t di/rict4 ,on ! ea/ side ( ! fault1 ! ,*alk is f\nd f> up ! slope1 circl+ r\nd ! base ( ! beautiful cone ( ,knocklayd--an outli] ( ! basalt :i* rea*es a height ( #afie feet 7,fig4 #bfc74 ,! am\nt ( v]tical displacem5t ( ! volcanic %eets is "h #gjj feet4#bca ,_m o!r displacem5ts1 z %[n by ! mapp+ ( my colleagues 9 ! ,geological ,survey1 h %ift$ ! base ( ! esc>pm5t f a few in*es up to sev]al hundr$ feet4 ,besides actual dislocations1 ! ,antrim plateau has und]gone "s m>k$ subsid5ces ( :i* ! mo/ notable is t ( ,l\gh ,neagh4#bcb ,footnote #bca3 ,explanatory ,memoir ( ,%eets #g & #h1 ,geological ,survey1 ,irel&1 by ,messrs4 ,symes1 ,egan1 & ,m',h5ry 7#ahhh71 p4 #cg4 ,footnote #bcb3 ,^! inequalities 9 ! level ( ! base ( ! ,antrim plateau w be m p>ticul>ly discuss$ 9 ,*apt] xlix41 9 connection ) ! subsid5ces & dislocations :i* h affect$ ! region s9ce ! close ( ! volcanic p]iod4 ,x is evid5t1 !re=e1 t ! pres5t position ( ! ,*alk plat=m is f> f agree+ ) t :i* x pres5t$ to ! outfl[ ( ! %eets ( basalt4 ,b1 on ! o!r h&1 !re c be no d\bt t its surface at ! beg9n+ ( ! volcanic outbur/s 0 n a level pla94 ,x 0 probably a roll+ c\ntry ( l[ b>e *alk-d[ns1 l p>ts ( ! ,s\?-ea/ ( ,engl&4 ,! ,iri% ,*alk atta9s its maximum ?ickness ( p]haps #bej feet at ,ball9toy4 ,b x is liable to rapid dim9ution4 ,on ! %ore at ,ballyca/le ab\t #aej feet ( x c be se51 its base be+ conceal$2 b only two & a half miles to ! s\?1 on ! outli] ( ,knocklayd1 ! ?ickness is n q half s mu*4 ,on ! we/ side ( ! plateau also1 !re are rapid *anges 9 ! ?ickness ( ! ,*alk4 ,su* v>iations appe> to be ma9ly attributable to unequal erosion be=e ! ov]fl[ ( ! basalts4 ,s great inde$ _h be5 ! d5udation ( ! ,cretace\s & und]ly+ ,second>y =mations previ\s to ! beg9n+ ( ! volcanic eruptions1 t 9 "s places ! :ole ( ^! /rata _h be5 /ripp$ (f ! c\ntry1 s t ! old] plat=m ( ,palozoic or /ill m anci5t masses 0 laid b>e4 ,?us1 on ! we/ side ( ! esc>pm5t1 ! basalt /eals across ! ,*alk & comes to re/ directly ^u ,l[] ,c>bonif]\s rocks4 ,! au?ors :o h describ$ ! junction ( ! ,*alk & basalts 9 ,antrim h g5]ally ref]r$ to ! unev5 surface ( ! =m] rock z expos$ 9 any giv5 section4 ,! floor on :i* ! basalt lies is rem>kably irregul>1 ris+ into ridges & s9k+ into holl[s or tr5*es1 b almo/ ev]y:]e pres5t+ a lay] ( e>?y rubbi% made ( br[n f]rug9\s clays1 mix$ ) pieces ( fl9t1 *alk1 & ev5 basalt4#bcc ,! fl9ts are g5]ally r$d5$ & %att]y4 ,! *alk itself has be5 describ$ z indurat$1 & its fl9ts z p>tially burn$ by ! influ5ce ( ! ov]ly+ basalt4 ,b ,i h n notic$1 at any locality1 evid5ce ( alt]ation ( ! solid *alk1 except :]e dykes or intrusive %eets h p5etrat$ x4#bcd ,!re c be no d\bt t ! h>dness ( ! rock is an orig9al peculi>ity1 due to ! circum/ances ( its =mation4 ,! irregul> e>?y rubble1 t almo/ always int]v5es betwe5 ! *alk & ! base ( ! basalt1 l ! clay ) fl9ts s g5]al ov] ! ,*alk ( ,s\!rn ,engl&1 no d\bt repres5ts long-cont9u$ subrial wea!r+ previ\s to ! outfl[ ( ! basalt4 ,ev51 !re=e1 if !re 7 no o!r evid5ce1 we might inf] ) "s confid5ce f ?is lay] ( rubble1 t ! surface ov] :i* ! lavas 7 p\r$ 0 a t]re/rial "o4 ,"h & !re1 too1 we may detect traces ( ! subsid5ce ( ! basalt into swall[-holes dissolv$ 9 ! *alk subsequ5t to ! outfl[ ( ! basalt-%eets4 ,footnote #bcc3 ,portlock1 ,report on ,geology ( ,londond]ry1 etc4 7,geological ,survey71 p4 #aag4 ,footnote #bcd3 ,see ,portlock1 op4 cit4 p4 #aaf4 ,! ,antrim plateau is n only ! l>ge/ 9 ! ,briti% ,isl&s1 x is also ! mo/ cont9u\s & regul>4 ,x may be reg>d$1 inde$1 z "o unbrok5 %eet ( volcanic mat]ial1 n disrupt$ by any su* m\nta9\s masses ( intrusive rock z 9 ! o!r plateaux int]rupt ! cont9uity ( ! horizontal or g5tly incl9$ %eets ( basalt4 ,ar\nd its m>g91 inde$1 a few outli]s t[] above ! pla9s1 & s]ve z impressive memorials ( its losses by d5udation4 ,( ^!1 by mu* ! mo/ picturesque & impos+1 ?\gh n ! l(tie/1 is ,knocklayd already ref]r$ to1 :i* =ms s /rik+ a feature 9 ! nor?-ea/ ( ,antrim 7,fig4 #bfc74 ,illu/ration3 ,fig4 #bfc4--,section ( ,knocklayd1 an outli] ( ! ,antrim basalt-plateau ly+ on ,*alk4 #a4 ,cry/all9e s*i/s2 #b4 ,cretace\s /rata2 #c4 ,l[] basalts2 #d4 ,gr\p ( tuffs1 clays & iron-ore2 #e4 ,upp] basalts2 f4 ,fault4 ,! total ?ickness ( volcanic rocks 9 ! ,antrim plateau exce$s #ajjj feet2 b1 z ! upp] "p ( ! s]ies has be5 remov$ by d5udation1 ! :ole dep? ( lava orig9ally p\r$ out _c n[ be told4 ,a well-m>k$ gr\p ( tuffs & clays1 traceable ?r\gh\t a l>ge "p ( ,antrim1 =ms a good horizon 9 ! mid/ ( ! basalts1 :i* are ?us divisible into a l[] & upp] gr\p 7,fig #bfd74 ,! ,l[] ,basalts h a ?ickness ( f #djj to #ejj feet4 ,b1 z already m5tion$ 7p4 #aid71 !y die out 9 ab\t six miles to no m ?an #dj feet at ,ball9toy4 ,!y are di/+ui%$ by _! g5]ally cellul> & amygdaloidal "*1 & less frequ5tly column> /ructure4 ,! successive fl[s1 ea* av]ag+ p]haps above #ae feet 9 ?ickness1 are (t5 sep>at$ by ?9 r$ f]rug9\s clayey p>t+s1 sometimes by b&s ( gre5 or br[n f9e gravelly tuff4 ,! mo/ ext5sive ( ^! tuff-b&s occurs 9 ! l[] "p ( ! gr\p at ,ball9toy1 & c be trac$ along ! coa/ = ab\t five miles4 ,9 ! middle ( its c\rse1 ne> ! picturesque ,c>rick-a-raide1 x rea*es a maximum ?ickness ( ab\t #ajj feet & gradually dies out to ea/ & we/4 ,! neck ( co>se agglom]ate at ,c>rick-a-raide1 is d\btless ! v5t f :i* ?is mass ( tuff 0 dis*>g$ 7see ,fig4 #cja74 ,ow+ to ! ?9n+ out ( ! %eets ( basalts1 z !y approa* ! v5t1 ! tuff comes to re/ directly on ! ,*alk1 & = "s di/ance we/w>ds =ms ! actual base ( ! volcanic s]ies4#bce ,occasional seams ( c>bonace\s clays1 or ( lignite1 appe> 9 diff]5t horizons among ! basalts4 ,b5ea? ! :ole mass ( basalt1 inde$1 rema9s ( t]re/rial vegetation "h & !re occur4 ,?us1 ne> ,banbridge1 ,c\nty ,d[n1 a pat* ( lignite1 f\r feet t5 in*es ?ick1 und]lies ! basalt1 & re/s directly on ,silurian rocks4 ,su* fragm5t>y records are an int]e/+ memorial ( ! wood$ l&-surface ov] :i* ! e>lie/ outfl[s ( basalt spread4 ,footnote #bce3 ,see ,explanation ( ,%eets #g & #h ( ! ,geological ,survey ( ,irel& 7#ahhh71 p4 #bc4 ,illu/ration3 ,fig4 #bfd4--;,diagram-,section ( ! ,antrim ,plateau4 #a4 ,triassic s]ies2 #b1 #c4 ,rhaetic /rata & ,lias2 #d4 ,gre5s&2 #e4 ,*alk2 #f4 ,gravel & soil2 #g4 ,l[] gr\p ( basalts2 #h4 ,gr\p ( tuffs1 clays & iron-ore2 #i4 ,upp] gr\p ( basalts4 ,9 look+ at ! great basalt-esc>pm5ts ( ,antrim1 ! ,inn] ,hebrides or ! ,f>oe ,isl&s1 & 9 foll[+ ) ! eye ! successive %eets ( lava 9 ord]ly sequ5ce ( level b&s f ! break+ waves at ! base to ! beetl+ cre/ above1 we are apt to take note only ( ! pro(s ( regul>ity & repetition 9 ! outfl[s ( molt5 rock & to miss ! evid5ce t ^! outfl[s did n always rapidly foll[ ea* o!r1 b 7 sep>at$ by int]vals ( v>y+1 sometimes ev5 ( long duration4 ,"o ( ! mo/ frequ5t & conspicu\s pro(s ( su* int]vals is to be f\nd 9 ! r$ lay]s or p>t+s above ref]r$ to :i*1 ?r\gh\t all ! basalt-plateaux1 s commonly int]v5e betwe5 successive %eets ( basalt4 ,^! r$ /reaks _c fail to arre/ ! eye on ! coa/-precipices :]e by _! brilliant contra/ ( col\r1 !y help to emphasize ! b$d$ "* ( ! :ole volcanic s]ies4 ,exam9$ m closely1 !y are f\nd to consi/ ( clay or bole :i* %ades into ! decompos$ top ( ! b$ :]eon x lies1 & is usually some:at %>ply m>k$ (f f t :i* cov]s x4 ,?is lay] has long1 & ,i ?9k correctly1 be5 reg>d$ z due to ! atmosph]ic dis9tegration ( ! surface ( ! basalt on :i* x re/s1 be=e ! eruption ( ! ov]ly+ fl[4 ,x v>ies 9 ?ickness f a m]e l9e up to a foot or m1 & x passes into ! tuffs & clays :i* are sometimes int]pos$ betwe5 ! %eets ( basalts4 ,x may be look$ ^u z probably furni%+ evid5ce ( ! lapse ( an int]val suffici5tly ext5d$ to p]mit a consid]able subs]ial decay ( ! surface ( a lava-%eet be=e ! outfl[ ( ! next lava4 ,b an att5tive /udy ( ! plateaux discloses o!r & ev5 m rem>kable indications t ! pauses betwe5 ! consecutive basalt-b$s 7 frequ5tly s prolong$ z to all[ ext5sive topographical *anges to be made 9 a di/rict4 ,n[h]e is ! long duration ( "s ( ^! int]vals m impressively taught ?an 9 ! c5tral zone ( s$im5t>y /rata 9 ,antrim4 ,?is p]si/5t gr\p ( tuffs1 clays1 & iron-ore is g5]ally f #cj to #dj & sometimes z mu* z #gj feet ?ick4 ,f ! occurr5ce ( ! ore 9 x1 x has be5 explor$ m dilig5tly 9 rec5t ye>s ?an any o!r gr\p ( rocks 9 ! di/rict1 & its outcrop is n[ kn[n ov] mo/ ( ! plateau4 ,! iron-ore b$ v>ies f less ?an an in* up to #ah in*es 9 ?ickness1 & consi/s ( pisolitic concretions ( hmatite1 f ! size ( a pea to t ( a hazel nut1 wrapp$ up 9 a s(t o*re\s clayey matrix4#bcf ,:]e x is abs5t1 its place is sometimes tak5 by an alum9\s clay1 work$ z bauxite1 :i* has yield$ /umps ( trees & num]\s leaves & cones4 ,b5ea? ! iron-ore or its repres5tative1 lies :at is call$ ! pavem5t1--a f]rug9\s tuff1 #h to #aj feet ?ick1 re/+ on li?om>ge1--a lilac or violet mottl$ alum9\s e>? sometimes full ( r\nd$ blocks or bombs ( basalt4 ,! well-kn[n horizon = fossil plants at ,ballypallidy is a r$ tuff 9 ?is zone4 ,! section ( /rata betwe5 ! two basalt-gr\ps at ?is locality may s]ve z an illu/ration ( ! nature & arrangem5t ( ! deposits4#bcg ,footnote #bcf3 ,consult a good essay on ! ,iron-ore & ,basalts ( ,nor?-ea/ ,irel& by ,messrs4 ,tate & ,hold51 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxvi4 7#ahgj71 p4 #aea4 ,9 ?is pap] ! nature1 composition & modes ( orig9 ( ! iron-ore & its associat$ /rata are fully discuss$4 ,footnote #bcg3 ,a4 ,m',h5ry1 ,geol4 ,mag4 7#ahie71 p4 #bfc4 ,upp] ,basalt1 compact & (t5 column> %eets4 ,br[n lam9at$ tuff & volcanic clays4 ,lam9at$ br[n impure e>?y lignite1 #b feet #c in*es4 ,br[n & r$ v>iegat$ clays1 tuffs & s&y lay]s1 ) irregul> seams ( co>se conglom]ate compos$ ( r\nd$ & subangul> fragm5ts ( rhyolite & basalt1 #c feet #d in*es4 ,br[n1 r$ & yell[i% lam9at$ tuffs1 mud/ones1 & bole1 ) occasional lay]s ( f9e conglom]ate 7rhyolitic & basaltic71 pisolitic iron-ore b& & plant-b$s1 #h feet #aj in*es4 ,l[] basalt1 amygdaloidal4 ,9 "s ( ! ,ballypallidy tuffs ! mo/ frequ5t lapilli are pieces ( gre5 & br[n glass1 :i* ,mr4 ,watts comp>es ) ! pit*/one ( ,s&y ,braes1 ?\gh r>ely conta9+ ph5ocry/s z t rock does4 ,he has f\nd also 9 ^! /rata a small] proportion ( li?oidal rhyolites & occasionally fragm5ts ( basic rock4 ,! pale & col\r$ clays t occur 9 ?is m>k$ s$im5t>y int]calation h d\btless be5 produc$ by ! decomposition ( ! volcanic rocks & ! wa%+ ( _! f9e detritus by wat]4 ,possibly ?is decay may h be5 9 "p ! result ( solfat>ic action4 ,f true bauxite or alum9ium-hydrate1 ! s$im5ts v>y 9 composition & specific gravity & pass into alum9\s silicates & iron-ores4 ,!y seem to indicate a prolong$ int]val ( volcanic quiesc5ce :5 ! lavas & tuffs already erupt$ 7 d5ud$ & decompos$4#bch ,footnote #bch3 ,see a note on ,bauxite by ,pr(essor ,g4 ,a4 ,cole1 ,sci5tif4 ,trans4 ,royal ,dubl9 ,soc4 vol4 vi4 s]ies ii4 7#ahif71 p4 #aje4 ,! area ov] :i* ?is int]e/+ s]ies ( /ratifi$ deposits n[ ext5ds is obvi\sly mu* less ?an x 0 orig9ally4 ,x has inde$ be5 s r$uc$ by d5udation into m]e scatt]$ pat*es t x probably does n exce$ #agj squ>e miles4 ,b ! gr\p c be trac$ f ,divis ,hill1 ne> ,belfa/1 to ,ra?l9 ,isl&1 a di/ance ( #ej miles1 & f ! valley ( ! ,bann to ! coa/ above ,gl5>m1 m ?an #bj miles4 ,!re c be little d\bt t x 0 once cont9u\s ov] all t area1 & t x probably ext5d$ "s way fur!r on ea* side4 ,if ! s-call$ ,plioc5e clays ( ,l\gh ,neagh be reg>d$ z p>ts ( ?is gr\p ( /rata1 its ext5t w be /ill fur!r increas$4 ,h5ce ! orig9al area ov] :i* ! iron-ore & its accompany+ tuffs & clays 7 laid d[n c h>dly h be5 less ?an #ajjj squ>e miles4 ,?is ext5sive tract 0 evid5tly ! site ( a lake dur+ ! volcanic p]iod1 =m$ by a subsid5ce ( ! floor ( ! l[] basalts4 ,! salts ( iron conta9$ 9 solution 9 ! wat]1 :e!r d]iv$ f ! decay ( ! surr\nd+ lavas or f ! dis*>ges ( *alybeate spr+s1 7 precipitat$ z p]oxide 9 pisolitic =m1 z simil> ores are n[ be+ =m$ on lake-bottoms 9 ,sw$54 ,= a long int]val1 quiet s$im5tation w5t on 9 ?is lake1 ! only sign ( volcanic en]gy dur+ t "t be+ ! du/ & /ones t 7 ?r[n out & fell ov] ! wat]-bas91 or 7 wa%$ into x by ra9s f ! cones ( ! lava-slopes ar\nd4 ,x may "h be rem>k$ t ! t5d5cy to subsid5ce 9 ! ,antrim plateau seems to h *>act]iz$ ?is region s9ce an e>ly "p ( ! volcanic p]iod4 ,! lake 9 :i* ! deposits n[ describ$ accumulat$ 0 entirely effac$ & ov]spread by ! ?ick gr\p ( upp] basalts4 ,b long aft] ! eruptions _h ceas$1 a r5ew$ s9k+ ( ! gr\nd gave rise to ! %eet ( wat] :i* n[ =ms ,l\gh ,neagh4#bci ,footnote #bci3 ,?is subject w be discuss$ 9 ,*apt] xlix4 ,n[h]e else among ! ,t]ti>y basalt-plateaux ( ,brita9 has any trace be5 f\nd ( s m>k$ & prolong$ a pause 9 ! volcanic activity z is indicat$ by ! ,antrim zone ( tuffs & clays4 ,?r\gh\t ! ,inn] ,hebrides1 inde$1 num]\s int]calations ( s$im5t>y mat]ial occur among ! basalts1 b ^! consi/ ma9ly ( tuffs & volcanic conglom]ates ) less frequ5t %ales & coal-seams1 & !y nev] sugge/ s di/9ct & l5g!n$ an int]val z is indicat$ by ! ,antrim deposit4 ,x is n improbable t ?is int]val 0 m>k$ by ! outbreak ( rhyolitic eruptions some:]e 9 ! region4 ,! abundance ( rhyolite fragm5ts 9 "s ( ! tuffs is /rik+ evid5ce t acid rocks 7 9 "o way or o!r br\ght to ! surface at ?is "t4 ,at ,gl5>m "o ( ! memb]s ( ! /ratifi$ s]ies is a m>k$ rhyolitic conglom]ate1 compos$ ( r\nd$ pebbles ( a rock n unlike ! well-kn[n rhyolite ( ,t>dree & ,c>ne>ny4 ,^! fragm5ts1 obvi\sly ( local orig91 mu/ ei!r h be5 d]iv$ f a surface ( acid rock laid b>e by d5udation1 or f rhyolite eject$ 9 lapilli or p\r$ out 9 /reams4 ,i =m]ly believ$ t all ! ,antrim rhyolites _h be5 inject$ into ! basalts aft] ! close ( ! plateau-p]iod4 ,b ! prov$ abundance & wide ext5t ( ! rhyolitic detritus among ! s$im5ts associat$ ) ! iron-ore po9t to a possible outfl[ ( acid lavas ) accompany+ tuffs dur+ ! s$im5t>y int]val betwe5 ! two gr\ps ( basalt4 ,! *>act]s ( ! ,antrim rhyolites1 h[ev]1 w be m p>ticul>ly discuss$ 9 ,*apt] xlvii41 9 connection ) ! acid rocks ( ! ,t]ti>y volcanic s]ies4 ,imm$iately above ! iron-ore ( ,antrim1 or sep>at$ f x 9 places by only a few in*es ( tuff1 comes ! gr\p ( ,upp] ,basalts1 :i* v>ies up to #fjj feet 9 ?ickness1 ?\gh z ! upp] portion has be5 ev]y:]e remov$ by d5udation1 no measure rema9s ( :at may h be5 ! orig9al dep? ( ! gr\p4 ,! g5]al "* ( ^! basalts is m frequ5tly column>1 black & compact1 & ) few] examples ( a /rongly amygdaloidal /ructure ?an 9 ! l[] gr\p4 ,b ?is di/9ction is less m>k$ 9 ! s\? ?an 9 ! nor? ( ,antrim1 s t :]e ! int]v5+ zone ( tuffs & iron-ore disappe>s1 no satisfactory l9e ( division c be trac$ betwe5 ! two gr\ps ( basalt4 ,! occurr5ce ( t zone1 h[ev]1 by giv+ rise to a holl[ or slope1 f :i* ! upp] basalts rise z a /eep bank or cliff1 furni%es a conv5i5t topographical feature = mapp+ ! b\nd>y ( ^! rocks4 ,among ! upp] basalts1 also1 !re is p]haps a less frequ5t occurr5ce ( ^? ?9 r$ p>t+s ( bole betwe5 successive fl[s1 s conspicu\s 9 ! l[] gr\p4 ,b ! fl[s are n less di/9ctly m>k$ (f f ea* o!r4 ,n[h]e c _! *>act]i/ic features be bett] se5 ?an along ! magnific5t range ( cliffs f ! ,giant's ,causeway ea/w>ds4 ,! column> b$ t =ms ! ,causeway is ! l[e/ %eet ( ! upp] gr\p1 & may be se5 re/+ directly on ! zone ( grey & r$ tuffs4 ,x is ab\t #fj or #gj feet ?ick2 &1 :ile p]fectly regul> 9 its column> /ructure at ! ,causeway & ! ,organ1 assumes fur!r ea/w>d ! confus$ly />*-l arrangem5t ( prisms already ref]r$ to4 ,b 9 ! great cliff section ( ! ,amphi!atre1 ! m regul> /ructure is resum$1 ! b$ swells out to ab\t #hj feet 9 ?ickness1 & columns ( t l5g? run up ! face ( ! precipice1 wea!r+ out at ! top into sep>ate pill>s1 :i*1 p]*$ on ! cre/ ( an out/&+ ridge1 are kn[n z ! ,*imneys4 ,! basalt-b$s t succe$ ! l[e/ "o are ea* only ab\t #aj to #ae feet ?ick 7,fig4 #bfe74 ,illu/ration3 ,fig4 #bfe4--,view ( ,basalt esc>pm5t1 ,giant's ,causeway1 ) ! ,amphi!atre & ,*imneys4 7,f a photograph by ,mr4 ,r4 ,wel*47 ,betwe5 ! successive %eets ( ! ,upp] ,basalts ?9 seams ( r$ f]rug9\s clay ?\gh1 z ,i h said1 less frequ5t p]haps ?an 9 ! l[] gr\p1 cont9ue to %[ t ! int]vals betwe5 successive eruptions 7 ( suffici5t duration to admit ( "s subrial decay ( ! surface ( a lava be=e ! outfl[ ( ! next b$4 ,occasional ?9 lay]s ( tuff also1 & ev5 ( pisolitic iron-ore1 h be5 obs]v$ among ^! high] basalts4 ,b ! mo/ int]e/+ & important int]calations are incon/ant seams ( lignite4 ,"o ( ! mo/ conspicu\s ( ^! lies imm$iately above ! basalt ( ! ,causeway1 :]e x 0 long work$ = fuel1 & 0 f\nd to be m ?an six feet ?ick4 ,b x is q local1 z may be se5 at ! ,organ ov] :i* x lies1 hav+ a ?ickness ( only #ab in*es & rapidly dy+ out s z to all[ ! basalts above & bel[ x to come toge!r4 ,! removal ( ! upp] portion ( ! basalts by d5udation has de/roy$ ! records ( ! late/ "p ( ! volcanic hi/ory ( ! ,iri% plateaux4 ,x is obvi\s t n[h]e 9 ,antrim does any trace exi/ ( a c5tral v5t or cone f :i* ! volcanic mat]ials 7 dis*>g$4 ,!re is no p]ceptible ?ick5+ ( ! individual basalt-%eets1 nor ( ! :ole s]ies 9 "o g5]al direction1 9 su* a mann] z to po9t to ! site ( "s *ief focus ( eruption4 ,nor c we place reliance on ! incl9ation ( ! sev]al p>ts ( ! plateau4 ,i h po9t$ out t ! v>y+ dip ( ! b$s mu/ be attribut$ ma9ly to po/-volcanic movem5ts1 or at lea/ to movem5ts :i*1 if n lat] ?an all ! phases ( volcanic action1 mu/ h succe$$ ! outp\r+ ( ! plateau-basalts4 ,!re has be5 a g5]al subsid5ce t[>ds ! c5tral & s\!rn tracts n[ occupi$ by ! valley ( ! ,bann & ,l\gh ,neagh4 ,b n[h]e 9 ! depression is !re any trace ( ! ru9s ( a c5tral cone or focus ( dis*>ge4 ,! ,antrim plateau1 9 ^! respects1 resembles ! o!rs4 ,b z has already be5 rem>k$1 x diff]s f !m 9 "o important p>ticul>4 ,x has n[h]e be5 disrupt$ by huge bosses ( y\ng] rocks1 su* z h brok5 up ! cont9uity ( ! old lava-fields fur!r nor?4 ,yet x also is n )\t its memorials ( y\ng] protrusions4 ,x conta9s n a few excell5t examples ( true volcanic v5ts1 &1 z above /at$1 x includes "s small acid bosses t may repres5t ! great protrusions ( ! ,inn] ,hebrides1 & may h be5 connect$ ) sup]ficial outfl[s ( rhyolitic lava & %[]s ( rhyolitic tuff4 ii4 ,,mull1 ,,morv5 ,,& ,,ardnamur*an ,?is plateau cov]s ne>ly ! :ole ( ! isl& ( ,mull1 embraces a portion ( ,morv5 on ! ,argyle%ire ma9l&1 &1 /ret*+ across ,lo* ,sun>t1 includes ! we/]n "p ( ! p59sula ( ,ardnamur*an 7,map ,,vi474 ,t ^! n[ disconnect$ areas 7 once unit$ into a cont9u\s lava-field :i* ext5d$ f> beyond its pres5t limits is impressively indicat$ by _! m>g9 ( cliffs & fr+e ( scatt]$ isl&s & outli]s4 ,! plateau w5t we/1 at lea/1 z f> z ! ,tre%ni% ,isles1 :i* are compos$ ( basalt4 ,on its ea/]n bord]1 a capp+ ( basalt on ! top ( ,be9n ,iada9 7#ahgc feet7 9 ,morv51 & o!rs fur!r nor?1 prove t its volcanic %eets once spread into ! int]ior ( ,argyle%ire 7,fig4 #bff74 ,on ! s\?1 its f9e range ( l(ty cliffs1 ) _! horizontal b>s ( basalt1 be> witness to ! dim9ution :i* x has und]gone on t side2 :ile1 on ! nor?1 simil> sea-walls tell ! same tale4 ,n only has x suff]$ by wa/e along its m>g91 x has also be5 deeply tr5*$ by ! excavation ( gl5s & arms ( ! sea4 ,! ,s\nd ( ,mull cuts x 9 two1 & ! ma9l& portion is fur!r bisect$ by ,lo* ,sun>t1 & aga9 by ,lo* ,al9e4 ,! isl& ( ,mull is s p5etrat$ by sea-lo*s & divid$ by deep valleys t a comp>atively slight depression w\ld turn x into a gr\p ( isl&s4 ,b1 besides its enorm\s d5udation1 ?is plateau has be5 subject$ to disruption1 & p]haps also to subsid5ce1 f subt]ranean movem5ts4 ,9 ! s\!rn portion ( ! isl& ( ,mull x has be5 brok5 up by ! intrusion ( l>ge bosses & %eets ( gabbro1 & by masses z well z innum]able ve9s ( v>i\s granitoid & felsitic rocks4 ,9 ,ardnamur*an1 x has suff]$ s mu* di/urbance f ! same cause t its orig9al /ructure has be5 almo/ oblit]at$ ov] a consid]able area4 ,moreov]1 x has be5 dislocat$ by _m faults1 by :i* diff]5t portions h be5 greatly %ift$ 9 level4 ,! mo/ important ( ^! breaks is "o notic$ by ,pr(essor ,judd1 & visible to e t\ri/ :o sails up ! ,s\nd ( ,mull4 ,x trav]ses ! cliffs on ! ,morv5 side1 opposite ,craignure1 br++ ! basalts aga9/ ! cry/all9e s*i/s1 & /rikes !nce inl&1 :eel+ r\nd into ! long valley 9 :i* ,lo*s ,ari5as & ,teacus lie4 ,on its we/]n side1 ! base ( ! basalt-s]ies is almo/ at ! sea-level2 on its ea/]n side1 t plat=m rises high into ! outli]s ( ,be9n na h-,uamha 7#aeba feet7 & ,be9n ,iada94 ,! am\nt ( displacem5t is probably m ?an #ajjj feet4 ,_m o!r m9or faults 9 ! same di/rict %[ h[ mu* ! cru/ ( ! e>? has be5 fractur$ "h s9ce old] ,t]ti>y "t4 ,illu/ration3 ,fig4 #bff4--;,basalt-capp+ on top ( ,be9n ,iada91 ,morv54 ,! hummocky gr\nd to ! "r consi/s ( ! ,highl& s*i/s aga9/ :i* ! basalts are br\ght by l9es ( dislocation4#bdj ,footnote #bdj3 ,!re are no few] ?an ?ree faults 9 ! basalt-capp+ on ! summit ( ,be9n ,iada94 ,by br++ ! basalts & s*i/s into juxtaposition1 !y h giv5 rise to topographical features t c be se5 ev5 f a di/ance4 ,a little to ! we/ ( ,mull1 & belong+ orig9ally to ! same plateau1 lies ! isle ( ,/affa1 ! fam\s column> basalts ( :i* fir/ attract$ ! att5tion ( travell]s1 & gave to ! ,t]ti>y volcanic rocks ( ,scotl& _! celebrity 7,fig4 #bff;a74 ,illu/ration3 ,fig4 #bff;a4--,view ( ! s\? side ( ,/affa1 %[+ ! b$d$ & column> /ructure ( ! basalt4 ,! rock 9 :i* ! cave to ! left h& has be5 erod$ is a conglom]atic tuff und]ly+ ! basalt2 to ! "r is ,f+al's ,cave4 ,^! cav]ns be> witness to ! enorm\s erosive p[] ( ! ,atlantic break]s4 ,9 spite ( ! ext5t to :i* x has suff]$ f d5udation & subt]ranean di/urbance1 & inde$ 9 consequ5ce !re(1 ! ,mull plateau pres5ts cle> sections ( _m features 9 ! hi/ory ( ! basalt-outfl[s & ( ! subsequ5t phases ( ,t]ti>y volcanic action :i* _c be se5 9 ! m regul> & cont9u\s tablel& ( ,antrim4 ,moreov]1 x /ill possesses 9 its highe/ m\nta91 ,b5 ,m 7#cafi feet71 a great] ?ickness1 & probably a high] s]ies1 ( lavas ?an c n[ be se5 9 any o!r ( ! plateaux4 ,! difficulties1 already ref]r$ to 9 reg>d to ,antrim1 ( trac+ ! probable =m ( gr\nd on :i* ! volcanic eruptions began1 are ev5 great] 9 ! case ( ! ,mull plateau4 ,we c dimly p]ceive t ! depression 9 ! cry/all9e rocks ( ! ,highl&s :i* _h1 f at lea/ ! old] "p ( ! ,jurassic p]iod1 /ret*$ 9 a ,n4,n4,w4 direction along :at is n[ ! we/]n m>g9 ( ,argyle%ire1 lay b5ea? ! sea 9 ,jurassic "t1 & 0 !n m or less fill$ up ) s$im5t>y deposits4 ,! holl[ appe>s !reaft] to h become a l&-valley1 :5ce ! ,jurassic /rata 7 to a l>ge ext5t cle>$ out by d5udation be=e its subsequ5t subm]g5ce "u ! sea 9 :i* ! upp] ,cretace\s deposits accumulat$4 ,pr(essor ,judd has %[n t relics ( ^! ,cretace\s /rata appe> on bo? sides ( ! plateau f "u ! protect+ cov] ( basalt-%eets4 ,b1 be=e ! volcanic eruptions began1 ! area _h once aga9 be5 rais$ into l&1 & ! y\nge/ ,second>y =mations _h be5 ext5sively erod$4 ,9 _! g5]al aspect ! basalts ( ,mull agree ) ^? ( ,antrim1 & ! circum/ances "u :i* !y 7 erupt$ 7 no d\bt ess5tially ! same4 ,b consid]able diff]5ces 9 detail are obs]vable betwe5 ! succession ( rocks 9 ! two areas4 ,:5 ,i fir/ visit$ ! isl& 9 #ahff1 ! only available maps1 ) any pret5sions to accuracy1 7 ! ,admiralty *>ts2 b1 z ^! d n give ! int]ior except 9 a g5]aliz$ way1 x 0 difficult to plot sections f !m1 & to arrive at satisfactory conclusions z to ! ?ickness ( diff]5t gr\ps ( rock4 ,accord+ly1 z ! successive ne>ly flat fl[s ( basalt c be trac$ f ! sea-level up to ! top ( ,b5 ,m1 ,i cont5t$ myself ) ! fact t ! total dep? ( lava-b$s 9 ,mull 0 at lea/ equal to ! height ( t m\nta91 or #cafi feet4 ,! publication ( ! ,ordnance ,survey ,maps n[ enables u to make a ne>] approximation to ! tru?4 ,f ! we/]n base ( ! magnific5t headl& ( ,gribon1 ! basalts 9 almo/ horizontal b$s rise 9 "o va/ sweep ( precipice & t]rac$ slope to a height ( ov] #afjj feet1 & !n /ret* ea/w>ds to pass "u ! high] "p ( ,b5 ,m1 at a di/ance ( "s eight miles4 ,!y h a slight ea/]ly incl9ation1 s t ! basem5t %eets se5 at ! sea-level1 at ! m\? ( ,lo* ,scrida91 gradually s9k bel[ t level z !y g ea/w>d4 ,x is n easy to get a measurem5t ( dip among ^! basalts1 except f a di/ance4 ,if we take ! incl9ation at only #a1 ! b$s :i* are at ! base ( ! cliff on ! we/1 mu/ be ab\t #gjj feet bel[ ! sea on ! l9e ( ,b5 ,m1 :i* w\ld give a total ?ickness ( ne>ly #cijj feet ( b$d$ lava bel[ ! top ( t m\nta94 ,we %all n probably ov]e/imate ! ?ickness ( ! ,mull plateau if we put x at #cejj feet4 ,! base ( ! volcanic s]ies ( ,mull c be/ be se5 on ! s\? coa/ at ,c>saig1 & at ! foot ( ! precipices ( ,gribon4 ,z already /at$1 x is !re f\nd re/+ above ,cretace\s & ,jurassic rocks4 ,! l[e/ b$s are basalt-tuffs1 ( ! usual dull gre5 col\r4 ,!y are 9 places mu* int]m+l$ ) s&y & gravelly s$im5t1 z if ! volcanic debris _h fall5 into wat] :]e su* s$im5t 0 9 c\rse ( deposition4 ,"o ( ! mo/ int]e/+ features1 inde$1 9 ?is basem5t "p ( ! s]ies1 is ! occurr5ce ( b&s ( non-volcanic mat]ial :i* accumulat$ aft] ! tuffs & "s ( ! lavas _h be5 erupt$1 b be=e ! ma9 mass ( basalts4 ,^? at ,c>saig include a l5ticul> b$1 #be feet ?ick1 ( roll$ fl9ts1 :i*1 ) "s associat$ s&y b&s1 lies betwe5 %eets ( basalt4 ,on ! opposite side ( ! promontory is ! well-kn[n locality ( ,ardtun1 f :i* ! fir/ l&-plants 9 ! volcanic s]ies 7 det]m9$4 ,! actual base ( ! basalts is n !re se51 be+ cov]$ by ! sea4 ,! leaf-b$s1 ) _! accompany+ s&/ones1 gravels1 & lime/one1 lie ^u a %eet ( basalt1 :i* 9 "s p>ts is exce$+ly slaggy on ! top1 pass+ d[n into a black compact /ructure1 & assum+ at ! base ( ! cliff a column> arrangem5t1 ) ! prisms curv$ & built up endways t[>ds ea* o!r4 ,"s ( ! gravels exce$ #cj feet 9 ?ickness1 & consi/ ( roll$ fl9ts1 bits ( *alk1 & pieces ( basalt & o!r basic igne\s rocks4 ,b "s ( _! mo/ int]e/+ +r$i5ts are pebbles ( sanid9e lavas1 :i* h be5 recogniz$ 9 !m by ,pr(4 ,g4 ,cole4#bda ,no kn[n protrusions ( su* lavas occur any:]e b5ea? or int]/ratifi$ ) ! plateau-basalts ( ?is di/rict4 ,z w be aft]w>ds %[n1 all ! visible acid rocks1 ! geological relations ( :i* c be asc]ta9$1 are "h ( y\ng] date ?an ^! basalts4 ,i am dispos$ to reg>d ! fragm5ts f\nd 9 ! ,ardtun conglom]ates z probably d]iv$ f "s ( ! basalt-conglom]ates ( ! plateau1 9 :i* fragm5ts ( silice\s igne\s rocks d occur4 ,?\gh !re is no evid5ce t any lavas ( t nature 7 "h p\r$ out at ! surface be=e or dur+ ! emission ( ! basalts1 ! cont5ts ( ^! fragm5tal volcanic accumulations sugge/ t su* lavas1 already consolidat$1 lay at "s dep? b5ea? ! surface1 & t fragm5ts 7 torn (f f !m dur+ ! explosions t ?rew out ! mat]ials ( ! basalt-conglom]ates to ! surface4 ,footnote #bda3 ,qu>t4 ,j\r4 ,geol4 ,soc4 xliii4 7#ahhg7 p4 #bgg4 ,! succession ( /rata at ! ,ardtun headl& v>ies consid]ably 9 a %ort di/ance1 "s ( ! s$im5t>y deposits rapidly increas+ or dim9i%+ 9 ?ickness4 ,! section z measur$ by ,mr4 ,/>kie ,g>dn] is z foll[s#bdb3-- ,column> basalt1 #dj feet4 ,position ( fir/ leaf-b$1 obscur$ by grass1 ab\t #b feet4 ,gravel v>y+ f ab\t #be feet to a maximum ( ne>ly #dj feet4 ,black or second leaf-b$1 #b-a_/b feet4 ,gravel ab\t #g feet4 ,grey clay1 #b feet4 ,lam9at$ s&/one1 #f in*es1 ) #c in*es ( f9e lime/one1 conta9+ leaves at ! base4 ,clay1 ) leaves at base1 #a foot4 ,clun*1 ) rootlets1 #g in*es4 ,amorph\s basalt1 becom+ column> at base1 ab\t #fj feet4 ,footnote #bdb3 ,op4 cit4 p4 #bhj4 ,mr4 ,/>kie ,g>dn] has call$ att5tion to ! extraord9>ily fre% condition ( ! vegetation 9 "s ( ! lay]s ( ! ,ardtun section4 ,"o ( ! leaf-b$s he has f\nd to be made up = an in* or two ( a press$ mass ( leaves1 ly+ lay] ^u lay]1 & reta9+ almo/ ! col\rs ( dead vegetation4 ,among ! plants repres5t$ is a l>ge purple ,g9kgo & a f9e ,platanites1 "o leaf measur+ #ae-a_/b in*es long by #aj-a_/b broad4 ,! *>act]i/ic dicotyl$on\s leaves at ?is locality possess$ relatively l>ge foliage4#bdc ,footnote #bdc3 ,= full] local details reg>d+ ! ,ardtun leaf-b$s1 ,i may ref] to ! orig9al pap] by ! ,duke ( ,argyll 7,qu>t4 ,j\r4 ,geol4 ,soc4 vii4 p4 #hi71 & to ! memoir by ,mr4 ,/>kie ,g>dn] 7op4 cit4 xliii4 7#ahhg71 p4 #bgj74 ,to ! e>ly obs]vations ( ,maccullo* we are indebt$ = ! record ( an int]e/+ fact 9 connection ) ! vegetation ( ! l&-surface ov] :i* ! fir/ lava-fl[s spread4 ,he figur$ a v]tical tree trunk1 imb$d$ 9 prismatic basalt1 & rightly ref]r$ x to "s species ( fir4#bdd ,?is relic may /ill be se5 "u ! basalt precipices ( ,gribon4 ,mr4 ,g>dn] f\nd x to be a l>ge trunk ( a conif]\s tree1 five feet 9 diamet]1 p]haps ,podoc>pus1 :i* has be5 envelop$1 z x /ood1 9 "o ( ! fl[s ( trap to ! height ( #dj feet4 ,its solidity & gir? evid5tly enabl$ x to resi/ ! fire1 b x _h decay$ be=e ! next fl[ pass$ ov] x1 = its trunk is a holl[ cyl9d] fill$ ) debris1 & l9$ ) ! *>r$ wood4 ,a limb ( ano!r1 or p]haps ! same tree1 is 9 a fissure n f> (f4#bde ,footnote #bdd3 ,we/]n ,isl&s1 vol4 i4 p4 #efh1 & plate xxi4 ,fig4 #a4 ,footnote #bde3 ,qu>t4 ,j\r4 ,geol4 ,soc4 xliii4 p4 #bhc4 ,at diff]5t levels 9 ! volcanic s]ies ( ,mull1 b$s ( lignite & ev5 true coal are obs]vable4 ,^! seem to be always m]e l5ticul> pat*es1 only a few squ>e y>ds 9 ext5t4 ,! be/ example ,i h met ) lies among ! basalts ne> ,c>saig4 ,x is 9 "p a black glossy coal1 & p>tly dull & %aly4 ,"s ye>s ago x 0 betwe5 two & ?ree feet ?ick1 b n[1 ow+ to its hav+ be5 dug away by ! %eph]ds1 only "s six or eight in*es are to be se54 ,x lies betwe5 two basalt-fl[s1 & rapidly disappe>s on ei!r side4 ,m frequ5t ?an ^! incon/ant lay]s ( fossil vegetation are ! ?9 p>t+s ( tuff & lay]s ( r$ clay1 sometimes conta9+ iron-ore1 :i* occur at int]vals ?r\gh\t ! s]ies betwe5 diff]5t fl[s ( basalt4 ,b ev5 su* int]calations are ( trifl+ ?ickness1 & only ( limit$ ext5t4 ,! magnific5t precipices ( ,m',gorry's ,head & ,gribon expose a succession ( b$s ( column> amorph\s & amygdaloidal basalt1 :i* mu/ atta9 a ?ickness ( at lea/ #bejj feet1 be=e !y are ov]la9 by ! high] gr\p ( pale lavas 9 ,b5 ,m4 ,on ! ea/ side ( ! isl&1 ?9 tuffs & b&s ( basalt-conglom]ate occur on diff]5t horizons among ! b$d$ basalts1 f ne> ! sea-level up to ! summit ( ! ridge :i* culm9ates 9 ,be9n ,meadhon 7#bjhg feet71 ,dn-da-,ghaoi! 7#beab feet71 & ,ma9nir-nam-,fiadh 7#bdhc feet74 ,ref]5ce has already be5 made to ! rem>kably co>se "* ( "s ( ! breccias int]calat$ among ! basalts 9 ?is "p ( ,mull1 & to ! enorm\s dim5sions ( "s ( ! masses ( mica-s*i/ & qu>tzite :i* h be5 c>ri$ up f a dep? ( #bjjj feet or m by volcanic ag5cy 7see ante1 p4 #aif1 & ,fig4 #bfb74 ,above ! ord9>y compact & amygdaloidal basalt comes ! high] gr\p ( pale lavas already ref]r$ to z =m+ ! upp]mo/ "p ( ,b5 ,m1 :5ce x /ret*es cont9u\sly along ! po9t$ ridge ( ,a',*io*1 & !nce nor?w>ds into ,be9n ,fhada4 ,! same lavas are likewise f\nd 9 two outli]s1 capp+ ,be9n a' ,*raig1 a mile fur!r nor?1 & ,i h f\nd fragm5ts ( !m on "s ( ! l(ti] ridges to ! s\?-ea/4 ,?is highe/ & y\nge/ gr\p ( lavas 9 ! plateaux has be5 r$uc$ to m]e isolat$ pat*es1 & a little fur!r d5udation w remove x altoge!r4 ,yet x is n less ?an ab\t #hjj feet ?ick1 & consi/s ( b$d$ &esitic or tra*ytic lavas1 :i* alt]nate ) & foll[ cont9u\sly & con=mably ^u ! top ( ! ord9>y plateau-basalts4 ,^! dull1 f9ely cry/all9e or compact1 light-grey rocks wea!r ) a *>act]i/ic platy =m1 :i* has be5 mi/ak5 = ! b$d+ ( tuffs4 ,! fissility1 h[ev]1 has none ( ! regul>ity or p>allelism ( true b$d+1 & may be obs]v$ to run sometimes p>allel ) ! b$d+ ( ! %eets1 sometimes obliquely or ev5 at "r angles to x4 ,ev5 :]e ?is /ructure is be/ develop$1 ! truly cry/all9e nature ( ! rocks c readily be detect$4 ,"s ( !m are porphyritic & amygdaloidal1 ! v topmo/ b$ ( ! m\nta9 be+ a co>se amygdaloid4 ,int]calat$ ) ^! curi\s rocks !re are o!rs 9 :i* ! ord9>y *>act]s ( ! dol]ites & basalts ( ! plateaux c be recognis$4 ,! amygdaloids are (t5 full ( delicate prisms ( epidote4 ,9 ,mull1 z 9 ! o!r areas ( t]rac$ basalts1 we ev]y:]e meet ) g5tly incl9$ %eets1 :i* d n ?ick5 out individually or collectively 9 any giv5 direction1 except z ! result ( unequal d5udations4 ,s f> z ,i h be5 able to discov]1 !y af=d no evid5ce ( any great volcanic cone f :i* !y proce$$4 ,_! pres5t incl9ations are unque/ionably due1 z 9 ,irel&1 to movem5ts subsequ5t to ! =mation ( ! plateau4 ,9 ,lo*-na-keal !y dip g5tly to ! ,e4,n4,e42 9 ,ulva & ! nor?-we/ coa/ to ,n4,n4,e42 ne> ,sal5 to ,w4,s4,w4 on ! "o side1 & ,n4,w4 on ! o!r4 ,r\nd ! s\!rn & ea/]n m>g9s ( ! m\nta9\s tract ( ! isl&1 !y dip g5]ally inw>ds to ! high gr\nds4 ,! ,mull plateau pres5ts a /rik+ contra/ to t ( ,antrim1 9 ! extraord9>y ext5t to :i* x has be5 disrupt$ by lat] protrusions ( massive basic & acid rocks ov] a rudely circul> area1 ext5d+ f ! head ( ,lo* ,scrida9 to ! ,s\nd ( ,mull1 & f ,lo*-na-keal to ,lo* ,buy4 ,! b$d$ basalts h be5 invad$ by masses ( dol]ite1 gabbro1 & granophyre1 ) v>i\s alli$ k9ds ( rock4 ,!y h n only be5 di/urb$ 9 _! cont9uity1 b h und]gone consid]able metamorphism4 ,aga91 fur!r to ! nor?1 9 ! promontory ( ,ardnamur*an1 ! plateau has be5 disrupt$ 9 a simil> way1 & only a few recognisable fragm5ts ( x h be5 left4 ,^! *anges w be m appropriately discuss$ 9 connection ) simil> ph5om5a 9 ! o!r plateaux fur!r nor?4 ,,*apt] ,,xxxviii ,,! ,,basalt-,,plateau ,,( ,,! ,,p>i% ,,( ,,small ,,isles--,,riv]s ,,( ,,! ,,volcanic ,,p]iod iii4 ,,p>i% ,,( ,,small ,,isles ,,plateau ,! p>i% ( ,small ,isles includes ! isl&s ( ,eigg1 ,rum1 ,canna1 ,s&ay & ,muck 7,map ,,vi474 ,! fragm5t>y basalt-plateau :i* x conta9s1 al?\gh ! smalle/ ( ! :ole s]ies1 is surpass$ by none 9 ! v>iety & int]e/ ( its geology4 ,x conta9s by f> ! mo/ complete records ( ! riv]s :i*1 dur+ ! volcanic p]iod1 fl[$ across ! lava pla9s4 ,& x alone has pres]v$ a relic ( ! late/ lava :i*1 aft] ! basalt-plateau _h be5 built up & _h be5 greatly erod$1 fl[$ ov] ! d5ud$ surface 9 /reams ( volcanic-glass t f\nd _! way into a riv]-*annel & seal$ x up4 ,t ! fragm5ts ( ! basaltic plateau pres]v$ 9 ea* memb] ( ! gr\p ( ! ,small ,isles 7 once connect$ z a cont9u\s volcanic pla9 c h>dly be d\bt$4 ,inde$1 z already /at$1 !y 7 n improbably unit$ ) ! plateau ( ,skye on ! nor?1 & ) t ( ,mull1 ,morv5 & ,ardnamur*an oh ! s\?4 ,tak+ ! :ole space ( l& & sea )9 :i* ! basalt ( ,small ,isles is n[ conf9$1 we may compute x at n mu* less ?an #bjj squ>e miles4 ,9 ,eigg1 ,muck1 ,canna & ,s&ay ! basalts reta9 _! almo/ horizontal position1 & f und]nea? !m ! ,jurassic /rata em]ge 9 ! fir/ ( ^! isl&s4 ,! c5tral "p ( ! plateau 9 ! isl& ( ,rum has suff]$ greatly f d5udation4 ,x n[ consi/s ( f\r small outli]s ( basalt1 :i* lie at levels ( #abjj feet & upw>ds1 on ! we/]n slope4 ,! basalt is und]la9 by a ?ick mass ( r$ ,torridon ,s&/one1 :i*1 ) "s gneisses & s*i/s1 =ms ! g5]al und]ly+ plat=m ( ?is isl&4 ,^! rocks are d\btless a cont9uation ( ! r$ s&/one & s*i/s ( ,sleat1 9 ,skye1 & l !m h be5 subject$ to ^? po/-,cambrian convolutions & metamorphism :]eby ! ,lewisian ,gneiss & ,torridon ,s&/one h be5 br\ght above y\ng] rocks1 & h be5 cru%$ & roll$ out s z to assume a new s*i/ose arrangem5t4 ,be=e ! "t :5 volcanic action began1 a mass ( high gr\nd1 consi/+ ( ^! anci5t rocks1 /ood :]e ! isl& ( ,rum is n[ situat$4 ,! /reams ( basalt spread ar\nd x1 n only cov]+ ! surr\nd+ l[ tracts ( ,jurassic rocks1 b gradually accumulat+ aga9/ ! hills1 & ?us r$uc+ !m bo? 9 area & 9 height above ! pla94#bdf ,view$ f ,canna ! we/]n coa/ ( ,rum pres5ts a /rik+ picture ( ! g5]al relations ( ! volcanic masses ( ! ,inn] ,hebrides & ( ! enorm\s d5udation :i* !y h und]gone 7,fig4 #bfg74 ,! ,torridon ,s&/ones are !re se5 to m\nt into ranges ( hills1 capp$ ) outli]s ( ! basalt-plateau1 :ile beh9d rise ! great eruptive bosses ( gabbro & granophyre4 ,! edges ( ! %eets t =m ! outli]s w\ld1 if prolong$1 cov] ! nor!rn or l[] half ( ! isl&1 :]e pre-,cambrian rocks =m ! surface4 ,9 ! s\!rn half1 ! cont9uity ( ! basalt has be5 p>tly obscur$ & p>tly de/roy$ by ! protrusion ( ! great masses ( gabbro t =m ! s+ul>ly picturesque m\nta9 gr\p to :i* ?is isl& owes its prom95ce z a l&m>k f> & wide along ! ,we/ ,coa/ ( ,scotl&4 ,footnote #bdf3 ,t ! lava-fields did n completely bury ?is nucleus ( old] rocks has be5 suppos$ to be %[n by ! fragm5ts ( r$ s&/one f\nd 9 ! anci5t riv]-b$ ( ,eigg1 :i* 0 scoop$ out ( ! basalt-plateau & seal$ up "u pit*/one4 ,b ,i am dispos$ to ?9k t ^! fragm5ts1 toge!r ) ^? ( ,jurassic s&/one1 came1 n f ,rum1 b f "s di/rict m to ! nor? & ea/1 z w be expla9$ 9 a lat] page4 ,at ,canna1 a few miles to ! we/1 fragm5ts ( r$ s&/one n improbably d]iv$ f ,rum are abundant 9 ! conglom]ates betwe5 ! basalts4 ,illu/ration3 ,fig4 #bfg4--,view ( ,rum f ! h>b\r ( ,canna4 ,! gr\nd indicat$ by s+le birds is ! area ( ,torridon ,s&/one2 two birds1 ! plateau basalts2 ?ree birds1 ! gabbro j se5 at "o po9t above ! granophyre hills2 f\r birds1 ! granophyre4 ,! mo/ v>i$ & int]e/+ ( ! fragm5ts ( ! basaltic plateau 9 ! area ( ! ,small ,isles is t :i* =ms ! isl& ( ,canna1 ) its app5dage ,s&ay4 ,canna measures five miles 9 l5g? by f half a mile to a mile 9 bread?1 & consi/s entirely ( ! rocks ( ! plateau & _! accompanim5ts4 ,! basalts are expos$ along ! nor? coa/ 9 a range ( mural precipices ris+ to a height ( ab\t #fjj feet above ! sea4 ,f ! top ( t esc>pm5t ! gr\nd falls by successive rocky t]races & grassy slopes to ! s\!rn %ore-l9e4 ,s&ay1 connect$ ) ! l>ge isl& by a %oal & foot-bridge1 is two miles long & #bbj to ab\t #abjj y>ds broad4 ,its highe/ cliffs range along its s\!rn %ore to a height ( #aic feet1 :5ce !y slope g5tly nor?w>d into ! holl[ betwe5 ! two isl&s4 ,?is peculi> topography acc\nts = ! mann] 9 :i* ! geological sections ( mo/ int]e/ are di/ribut$4 ,! fir/1 & /ill ! be/1 acc\nt ( ! geology ( ^! isl&s is t ( ,maccullo*4 ,he %[$ t ! rocks all belong to ! s]ies ( ! plateau-basalts1 & he describ$ ! pres5ce among !m ( a trap-conglom]ate4 ,he notic$ ! occurr5ce also ( trap-tuff & ! occasional appe>ance ( c>boniz$ wood 9 ^! deposits4 ,reason+ ^u ^! obs]vations 9 8 *>act]i/ically vague & v]bose mann]1 bewild]$ 9 ! regions ( conjecture1 he concludes t ! basalts in/ead ( belong+ to "o g5]al =mation h be5 successively deposit$ on ! same spot1 s9ce lapse ( "t is evid5tly impli$ 9 ! =mation ( a conglom]ate4 ,he incl9es to believe t !y h be5 dis*>g$ by anci5t volcanoes f :i* 9 ! c\rse ( "t all traces ( _! orig9al outl9e h be5 m or less completely remov$1 ! exi/+ basalts be+ m]ely fragm5ts ( once m ext5sive masses4#bdg ,footnote #bdg3 ,we/]n ,isles1 vol4 i4 pp4 #ddh-dei1 & pl4 xix4 ,figs4 #b1 #c & #d4 ,see also ,jameson's ,m9]alogy ( ! ,scotti% ,isles4 ,maccullo* reg>d$ ! int]calat$-conglom]ates z hav+ be5 arrang$ "u wat] & z m>k+ pauses 9 ! deposition ( ! %eets ( trap4 ,he gave two diagrams 9 illu/ration ( ! relations ( ^! detrital deposits1 b he express$ no def9ite op9ion z to _! orig91 ?\gh f "o passage x w\ld seem t he incl9$ t[>ds ! belief t !y 7 =m$ 9 ! sea4#bdh ,s9ce 8 "t1 s f> z ,i am aw>e1 no fre% light has be5 ?r[n ^u ! subject4 ,footnote #bdh3 ,op4 cit4 pp4 #ddi1 #deg1 pl4 xix4 ,figs4 #b & #c4 ,dur+ a ya*t+ cruise 9 ! summ] ( #ahid ,i visit$ ,canna = ! fir/ "t & f\nd s mu* t 0 new to me 9 reg>d to ! hi/ory ( ,t]ti>y volcanic action1 & :i* dem&$ a c>eful survey1 t ,i return$ to ! locality ! foll[+ summ] & rema9$ 9 ! isl& until ,i _h mapp$ x & its dep5d5cies ^u ! ,ordnance ,survey %eets on ! scale ( six in*es to a mile4 ,! foll[+ n>rative is ! result ( ! obs]vations !n made4 ,z f> back z ! ye> #ahfe ,i publi%$ an acc\nt ( an anci5t riv]-*annel :i*1 dur+ ! volcanic p]iod1 _h be5 erod$ on ! surface ( ! basalt-plateau1 & ( :i* a small portion _h be5 pres]v$ "u a /ream ( pit*/one-lava t _h fl[$ into & buri$ x4#bdi ,?is wat]-c\rse1 n[ m>k$ by ! picturesque ridge ( ! ,scuir ( ,eigg1 0 %[n to h be5 excavat$ by a /ream :i* came f ! nor?-ea/ or ea/1 & to be y\ng]1 n only ?an ! plateau-basalts ( ! di/rict1 b ?an ev5 ! dykes :i* cut ^! basalts4 ,yet t x belong$ to ! volcanic p]iod 0 prov$ by ! mann] 9 :i* x _h be5 seal$ up & pres]v$ "u ! black glassy lava ( ! ,scuir4 ,its hi/ory & ! data f :i* ?is hi/ory is compil$ w be n>rat$ 9 a lat] "p ( ?is *apt]4 ,footnote #bdi3 ,sc5]y ( ,scotl& 7#ahfe72 ,qu>t4 ,j\rn4 ,geo4 ,soc4 vol4 xxvii4 7#ahga71 p4 #cjc4 ,my exam9ation ( ! isl&s ( ,canna & ,s&ay1 h[ev]1 br\ght to light o!r & m abundant evid5ce ( riv]-action 9 ! same region ( ! ,inn] ,hebrides1 b belong+ to an e>li] "p ( ! volcanic p]iod4 ,?is evid5ce reveals t a p[]ful riv]1 fl[+ we/w>ds f ! ,highl& m\nta9s1 swept ov] ! volcanic pla91 :ile ! %eets ( basalt 7 /ill be+ p\r$ =?1 & :ile volcanic eruptions 7 tak+ place f cones ( slag4 ,! basalt-plateau ( ,canna resembles 9 all ess5tial p>ticul>s ^? ( ! o!r ,we/]n ,isles4 ,its base is ev]y:]e conceal$ "u ! sea1 b f ! fragm5ts ( ,torridon ,s&/one 9 its agglom]ates we may inf] t x probably re/s on t =mation1 l ! volcanic outli]s 9 ,rum4 ,x is =m$ ( successive %eets ( diff]5t basalts includ+ ! usual b&$1 amygdaloidal & column> =ms4 ,"s ( !m t[>ds ! we/ are specially m>k$ by ! great abundance & l>ge size ( _! porphyritic felsp>s4 ,! magnetic prop]ties ( ! basalts at ! ea/ end ( ! isl& h long be5 kn[n1 & h giv5 rise to v>i\s mod]n my?s reg>d+ _! influ5ce on ! compasses ( pass+ vessels4 ,illu/ration3 ,fig4 #bfh4--,section ( ! cliffs bel[ ,compass ,hill1 ,isle ( ,canna4 ,b x is 9 its conglom]ates1 tuffs & agglom]ates & ! light !y ca/ on "s aspects ( ! volcanic p]iod1 else:]e h>dly record$1 t ! geology ( ,canna possesses a special importance4 ,to ^!1 !re=e1 we may at once turn4 ,! conglom]ates are be/ develop$ at ! ea/]n end ( ! isl&1 :]e ! cliffs pres5t ! /ructure repres5t$ 9 ,fig4 #bfh4 ,at ! base1 & pass+ "u ! level ( ! sea1 lies ! agglom]ate 7a7 ( a v5t :i* w be describ$ 9 ,*apt] xli41 toge!r ) o!r eruptive orifices ( ! v>i\s plateaux 7p4 #bhh74 ,?is rock has a some:at unev5 upp] surface :i* rises 9 places ab\t #aej feet above high tide-m>k4 ,"h & !re x %ades (f upw>d into ! conglom]ate t ov]lies x2 wat]-worn pebbles appe> among its cont5ts1 & rude traces ( b$d+ beg9 to %[ !mselves1 until1 )9 ! c\rse ( a few feet1 we pass upw>d into an und\bt$ conglom]ate4 ,else:]e1 h[ev]1 & p>ticul>ly along ! precipices we/ ( ,compass ,hill1 ! two deposits are m di/9ctly m>k$ (f f ea* o!r4 ,! agglom]ate has !re a hummocky1 irregul> upp] surface1 z if x _h be5 ?r[n d[n 9 heaps4 ,! holl[s betwe5 ^! protub]ances h be5 fill$ up ) conglom]ate & s&/one1 =m+ ! base ( ! ?ick ov]ly+ deposit4 ,x is ?us cle> t ! loose mat]ials ( ! v5t 7 directly expos$ at ! surface :5 ! conglom]ate 0 accumulat$1 &1 inde$1 t ^! mat]ials s]v$ to supply "s ( ! detritus ( :i* ! conglom]ate consi/s4 ,! abs5ce ( any trace ( a cone & crat] at ! v5t may p]haps be explicable on ! supposition t _! incoh]5t mat]ial 0 wa%$ d[n by ! curr5ts t swept along & deposit$ ! conglom]ate4 ,! mass ( s$im5t>y mat]ial 7b7 :i* ov]lies ! agglom]ate ( ! v5t =ms a conspicu\s feature along ! l[] half ( ! precipices at ! ea/]n end ( ,canna4 ,x rises to a height ( #bej to #cjj feet above sea-level1 & mu/ rea* a maximum ?ickness ( probably n less ?an #ajj to #aej feet4 ,x gradually desc5ds 9 a we/w>d direction1 bo? along ! nor!rn cliffs & 9 ! l[] gr\nd r\nd ,canna ,h>b\r1 insomu* t 9 ab\t a mile1 ow+ to ! g5tle we/]ly dip ( ! :ole volcanic s]ies1 comb9$ ) ! effect ( a numb] ( small faults1 x passes "u ! level ( ! sea4 ,great v>iation 9 ! "* ( ! detritus compos+ ?is ?ick gr\p ( /rata may be obs]v$ z x is foll[$ we/w>d4 ,on ! cliffs bel[ ,compass ,hill1 z repres5t$ 9 ,fig4 #bfh1 ! co>se conglom]ate ) wat]-worn /ones1 h>dly to be di/+ui%$ f ! volcanic agglom]ate ( ! v5t1 %[s m or less di/9ct b$d+1 or at lea/ a succession ( co>s] & f9] b&s4 ,t[>ds its base x encloses num]\s pieces ( ,torridon ,s&/one1 sometimes subangul>1 b (t5 s well & smoo?ly r\nd$ z to %[ t !y mu/ h be5 long subject$ to ! action ( mov+ wat]4 ,x is fur!r obs]vable t1 :ile 9 ! agglom]ate ! volcanic /ones h r\gh surfaces1 ^? 9 ! conglom]ate beg9 to %[ increas+ evid5ce ( attrition1 until1 z ! deposit is trac$ upw>ds1 !y become almo/ z well r\nd$ & wat]-worn z ! non-volcanic /ones4 ,yet amid/ & ov]ly+ ^! pro(s ( transport f "s little di/ance lie abundant huge slags & blocks ( amygdaloidal lava1 sometimes closely aggregat$1 sometimes scatt]$ ?r\gh a volcanic tuff or a%y s&/one4 ,! composition & /ructure ( ^! /ones1 & ! mann] ( _! disp]sion ?r\gh ! deposit1 leave little d\bt t !y 7 eject$ f ! v5t4 ,we are ?us confront$ ) ! int]e/+ fact t1 :ile ! mat]ials ( ! volcanic cone 7 be+ wa%$ d[n by runn+ wat]1 eruptions 7 /ill tak+ place4 ,b by degrees ^! indications ( contemporane\s volcanic activity dim9i%4 ,! detrital mat]ials become co>s] & m di/9ctly wat]-roll$ until !y pass into gre5i% s&/ones & f9e conglom]ates4 ,yet ! matrix ev5 ( ^! high] s$im5ts is l>gely compos$ ( f9e volcanic detritus1 & probably po9ts to occasional dis*>ges ( du/ & a%es4 ,v>i\s sills or intrusive %eets h be5 inject$ into ?is s$im5t>y gr\p along ! precipices at ! ea/ end ( ,canna1 & =m !re l5ticul> b&s4 ,"o ( ^! 7c7 is %[n 9 ,fig4 #bfh4 ,imm$iately above ! massive gre5i% pebbly s&/one 7d7 :i* caps ! /ratifi$ s]ies lies a gr\p ( basalts 7e71 compos$ ( sev]al di/9ct b$s1 hav+ a unit$ ?ickness ( f #hj to #ajj feet4 ,! l[e/ ( ^! has a regul> column> /ructure1 :ile ^? ov]ly+ x exhibit ! confus$ />*-l gr\p+ ( curv$ & r indi/9ctly-=m$ prisms4 ,! next b& 9 upw>d succession is "o ( conglom]ate 7f71 :i* runs z a cont9u\s & conspicu\s feature along ! upp] "p ( ! cliff4 ,?is rock pres5ts 9 _m respects a /rong contra/ to ! conglom]ates und]nea?4 ,x is dull-gre5 to yell[ 9 col\r1 & is well /ratifi$1 be+ m>k$ by ! int]/ratification ( f9] lay]s1 & pass+ d[n into a b& ( pebbly s&/one1 :i* re/s imm$iately on ! basalt 7e74 ,its compon5t /ones are ?or\ghly wat]-worn1 rang+ up to six in*es or ev5 m 9 l5g?4 ,b its mo/ di/9ctive "* lies 9 ! nature ( its pebbles4 ,in/ead ( consi/+ ma9ly ( volcanic mat]ials1 ^! /ones h almo/ all be5 transport$ = "s di/ance4 ,!y include abundant fragm5ts ( ,torridon ,s&/one1 gneiss1 s*i/s1 grits1 & o!r rocks l ^? 9 ,rum & ,we/]n ,inv]ness-%ire4 ,no su* rocks exi/ 9 situ 9 ,canna4 ,! ne>e/ tract ( ,torridon ,s&/one is 9 ,rum1 ab\t f\r miles to ! ea/w>d4 ,b ! pieces ( s*i/ & epidotic grit l ! rocks ( ! ,we/]n ,highl&s1 h probably travell$ at lea/ #cj miles4 ,x is important to obs]ve t all ^! transport$ /ones indicate a d]ivation f "s s\rce ly+ to ! ea/w>d ( ,canna4 ,! evid5ce 9 ?is respect agrees ) t furni%$ by ! anci5t riv]-gravel "u ! pit*/one ( ! ,scuir ( ,eigg4 ,x is cle> t ! wat]s :i* f\nd _! way across ! lava-fields ( ?is "p ( ! ,inn] ,hebrides took _! rise some:]e to ! ea/w>d1 probably among ! m\nta9s ( ,inv]ness-%ire4 ,! conglom]ate n[ describ$ is f #dj to #ej feet ?ick4 ,x c be foll[$ along ! face ( ! cliffs = m ?an a mile on ! nor? side ( ,canna4 ,less p]si/5t on ! s\? side1 its outcrop /rikes f ! edge ( ! precipice inl&1 keep+ to ! s\? ( ! top ( ,compass ,hill4 ,x is well se5 9 ! rav9e above ! ,coroghon1 b _c be foll[$ fur!r we/w>d among ! basalt-t]races4 ,yet1 ?\gh ?is /ratifi$ int]calation is n traceable f> z a b& ( conglom]ate1 ! same /ratigraphical horizon is probably indicat$ else:]e by o!r k9ds ( s$im5t>y deposits1 to :i* fur!r ref]5ce w be made 9 ! sequel4 ,! section n[ describ$ e/abli%es ! exi/5ce ( at lea/ two successive plat=ms ( conglom]ate 9 ! volcanic s]ies4 ,foll[+ ^! plat=ms along _! outcrop1 we obta9 additional light on _! orig91 & on ! topographical conditions "u :i* !y 7 deposit$1 & we le>n fur!r t o!r prolong$ int]vals1 :i* 7 likewise m>k$ by int]calations ( s$im5t>y mat]ial1 occurr$ 9 ! outp\r+ ( ! basalts4 ,tak+ fir/ ! l[] conglom]ate ( ,compass ,hill & trac+ x we/w>d1 we f9d x to =m ! depression 9 :i* ! %elt]$ inlet ( ,canna ,h>b\r lies4 ,x is expos$ along ! %ores & also 9 ! isl&s enclos$ )9 ! same bay4 ,b x is n traceable fur!r we/1 possibly because x seems to s9k b5ea? ! level ( ! sea4 ,to ! s\?-ea/1 ?\gh x is !re likewise = ! mo/ "p conceal$ "u ! waves1 x rises above !m 9 "o or two p>ts ( ! coa/-l9e ( ,s&ay1 p>ticul>ly at ! ,uamh ,ruadh or ,r$ ,cave1 & likewise on a surf-beat5 sk]ry (f ,ceann an ,eile91 ! highe/ "p ( ! ,s&ay cliffs--a di/ance ( ab\t a mile & a half f ,compass ,hill4 ,?r\gh\t ?is space x reta9s its rem>kably co>se "* & is ma9ly made up ( volcanic mat]ial4 ,! num]\s sections expos$ 9 ,canna ,h>b\r enable u to /udy ! composition & local v>iations ( ?is curi\s deposit4 ,on ! nor? side ( ! bas91 :ile ! l[] "p ( ! s$im5t>y s]ies cont9ues to be an exce$+ly co>se volcanic conglom]ate1 x passes upw>d into f9] conglom]ates1 tuffs1 & %ales4 ,9 front ( ,canna ,h\se ! imb$d$ blocks are ( l>ge size1 occasionally z mu* z ?ree or f\r feet 9 diamet]4 ,!y are /ill m gigantic on ! isl& ( ,eilean a' ,bhaird1 :]e ,i f\nd "o to conta9 #aej cubic feet 9 ! expos$ "p1 ! re/ be+ /ill conceal$ 9 ! matrix4 ,z !y are g5]ally some:at r\nd$1 "h & !re m>k$ly s1 mo/ ( ^! /ones h probably und]gone a c]ta9 am\nt ( attrition 9 wat]4 ,! great majority ( !m1 & c]ta9ly all ^? ( l>g] size1 are pieces ( basalt1 dol]ite1 &esite1 etc4 ,among !m huge blocks ( amygdaloid & co>sely vesicul> lava are specially abundant4 ,"s ( ^! look l pieces ( slag torn f ! upp] surface ( lava-/reams4 ,o!rs1 display+ a highly vesicul> c5tre & a close-gra9$ out] cru/1 are sugge/ive ( bombs4 ,x is int]e/+ to note "h aga9 t ! amygdaloidal blocks pres5t _! zeolitic infiltrations s precisely l ^? ( ! amygdaloids ( ! plateau t x seems reasonable to suppose ! c>bonate ( lime1 zeolites1 etc4 to h be5 introduc$ be=e ! blocks 7 imb$d$ 9 ! conglom]ate4 ,! :ole aspect ( ?is deposit is em95tly volcanic4 ,x looks l a va/ %eet ( lava-fragm5ts swept away f "o or m cones ( slags & c9d]s1 or f ! scoriace\s surface ( a lava-/ream4 ,:]e ! vesicles 7 /ill empty1 ! l>ge b\ld]s c\ld be m easily swept along by mov+ wat]4 ,b a p[]ful curr5t mu/ h be5 ne$$ to transport & we> d[n into m or less r\nd$ =ms blocks ( basic lava1 _m ( :i* mu/ weigh sev]al tons4 ,! l>ge block on ,eilean a' ,bhaird probably exce$s #ab tons 9 weight4 ,besides ! obvi\sly volcanic cont5ts ( ! conglom]ate !re occur "h also1 z 9 ! ,compass ,hill cliffs1 abundant pieces ( ,torridon ,s&/one4 ,^! /ones are notably small] 9 size & m p]fectly wat]-worn & ev5 poli%$ ?an ! blocks ( lava4 ,obvi\sly !y h travell$ fur!r & h und]gone m prolong$ attrition4 ,! matrix ( ! rock consi/s ess5tially ( ! f9e detritus ( basic lavas1 probably m+l$ ) true volcanic du/4 ,! co>s] p>ts display only ! feeble/ indication ( /ratification2 inde$1 9 a limit$ exposure ! rock might be reg>d$ z a tumultu\s agglom]ate4 ,b ! mann] 9 :i* ! deposit is int]calat$ )1 & sometimes ov]lies1 gre5 tuffs & %ales1 toge!r ) ! wat]-worn condition ( its /ones1 %[s t x has n be5 accumulat$ 9 a volcanic *imney1 b has be5 ?r[n d[n by "s p[]ful body ( wat]1 ) probably ! co-op]ation ( volcanic dis*>ges4 ,:ile ! composition ( ! conglom]ate suffices to indicate t ?is deposit 0 =m$ at a "t :5 "s volcano 0 active 9 ! imm$iate neighb\rhood1 s+ul>ly conv9c+ pro(s ( ! "w ( ?is v5t are to be se5 9 ! =m ( int]calat$ %eets ( lava4 ,?us on ,eilean a' ,bhaird ! b\ld]s ( ! conglom]ate are ov]la9 & wrapp$ r\nd by a %eet ( rudely prismatic basalt1 ) l9es ( vesicles arrang$ 9 ! direction ( ! b$d+4 ,a simil> relation c be trac$ along ! bea* betwe5 ,canna ,h\se & ! wood5 pi]1 :]e successive %eets ( basalt h fl[$ ov] ! conglom]ate 7,fig4 #bfi74 ,b1 besides co>se volcanic detritus1 ! s$im5t>y plat=m repres5t$ by ! l[] conglom]ate ( ,compass ,hill includes o!r deposits ( :i* good sections may be exam9$ all r\nd ,canna ,h>b\r4 ,b$s ( f9e well-/ratifi$ dull-gre5 tuff pass by an admixture ( pebbles into f9e a%y conglom]ate or pebbly s&/one1 & by an increase 9 ! proportion ( _! f9e detritus into volcanic mud/one & f9e %ales4 ,! %ales v>y f a pale grey or :ite tone into blacki% grey1 br[n1 & black4 ,!y are well /ratifi$ & are frequ5tly int]leav$ ) lay]s ( f9e tuff4 ,! d>k] b&s are c>bonace\s1 & are n infrequ5tly full ( ill-pres]v$ vegetation4 ,inde$1 leaves & /ems 9 a r mac]at$ condition are ( common occurr5ce 9 all ! %aly lay]s4 ,"h & !re1 especially 9 "s a%y %ales 9 front ( ,canna ,h\se1 ,i obs]v$ a recognisable ,sequoia4 ,! mud/ones are dull gre51 close-gra9$ %att]y rocks compos$ ( f9e volcanic detritus1 & pass bo? lat]ally & v]tically into %ales1 tuffs1 & conglom]ates4 ,!y sugge/ %[]s ( f9e du/ or /reams ( volcanic mud4 ,!y1 too1 conta9 fragm5t>y plants4 ,x is a notewor?y fact t ! s$im5t>y int]calations among ! ,canna basalts g5]ally end upw>d 9 c>bonace\s %ales or coaly lay]s4 ,! /rong curr5ts & ov]fl[s ( wat]1 :i* roll$ & spread out ! co>se mat]ials ( ! conglom]ates1 gave way to quiet] conditions t all[$ silt & mud to ga!r ov] ! wat]-bottom1 :ile leaves & o!r fragm5ts ( vegetation1 bl[n or wa%$ into ^! quiet rea*es1 7 ! la/ ( ! susp5d$ mat]ials to s9k to ! bottom4 ,good illu/rations ( ?is sequ5ce 9 ! case ( ! l[] conglom]ate zone ( ,canna may be /udi$ along ! %ores ( ,s&ay1 f ! ,ca?olic ,*apel ea/w>ds4 ,! f9e pebbly s&/ones1 tuffs1 & %ales1 :i* !re ov]lie ! co>se conglom]ate1 are surm\nt$ by d>k br[n or black c>bonace\s %ale1 ) l5ticles ( matt$ vegetation t pass into impure coal4 ,imm$iately ov]ly+ ?is coaly lay] comes a %eet ( prismatic vesicul> basalt1 foll[$ by ano!r ) an exce$+ly slaggy texture4 ,l5ticles ( %ale & mud/one likewise occur 9 ! he>t ( ! f9] p>ts ( ! conglom]ate1 especially t[>ds ! top1 z may be se5 9 ! section expos$ b5ea? ! basalt beh9d ! fir/ cottage we/ f ,canna ,h\se4 ,"o ( ! mo/ int]e/+ lay]s 9 ?is section is a seam ( tuff1 v>y+ up to ab\t two in*es 9 ?ickness1 :i* lies at ! top ( ! l5ticul> b& ( tuffs & %ales1 & imm$iately b5ea? ! b& ( basalt-conglom]ate1 on :i* a basalt1 c>ry+ a vesicul> b& ne> its bottom1 re/s4 ,trac$ lat]ally1 ! d>k br[n tuff ( ?is seam gradually passes into a s]ies ( r\nd$ bodies & flatt5$ %ells compos$ ( a col\rless m9]al :i* has evid5tly be5 develop$ 9 situ aft] ! deposition ( ! tuff4 ,mr4 ,h>k]'s notes on ?9 slices made f ?is b& are z foll[s3-- ,?is is a ru/y-br[n1 dull-look+ rock1 r s(t & seem+ly light1 b too absorb5t to p]mit ( its specific gravity be+ te/$4 ,! d>k br[n mass is 9 great "p /udd$ ) little sph]oidal bodies1 #a_/ej to #a_/aj in* 9 diamet]1 ( pal] col\r1 b ! l>g] ones hav+ a d>k nucleus4 ,9 o!r p>ts l>g] flat bodies h be5 =m$1 z if by ! coalesc5ce ( ! sph]oids1 ext5d+ z incon/ant b&s 9 ! direction ( lam9ation = p]haps #a_/b in*1 ) a ?ickness ( #a_/aj in* or less4 ,! appe>ance is t ( a sph]ulitic r ?an an oolitic /ructure4 ,a slice #ffeh ,a %[s ! g5]al mass ( ! rock to be ( an extremely f9ely divid$ b coh]5t sub/ance ( br[n col\r1 :i* c sc>cely be o!r ?an a f9e volcanic du/1 compos$ ( m9ute p>ticles ( basic glass or 'palagonite' compact$ toge!r4 ,scatt]$ ?r\gh ?is are fragm5ts ( cry/als recognizable z tricl9ic & p]haps monocl9ic felsp>s1 gre5 hornbl5de1 augite1 oliv9e 7871 & magnetite1 usually q fre%4 ,! curi\s sph]oidal & elongat$ gr[?s already m5tion$ are bett] se5 9 ano!r slide #ffeh ,b1 :]e !y occupy ! l>g] "p ( ! field1 leav+ only an int]/itial framework ( ! br[n matrix4 ,! sub/ance ( ! little sph]oids is cle>1 col\rless1 & app>5tly /ructureless4 ,! c5tre is (t5 occupi$ by an irregul>ly /ellate pat* ( br[n col\r1 & sometimes cracks t5d to run 9 radiat+ fa%ion1 b ^! are ! only indications ( radial /ructure4 ,! out] b\nd>y is %>ply def9$1 & :]e ! slice is %att]$ ! sph]oids h sep>at$ f ! matrix4 ,! matrix is d>k] ?an 9 ! normal rock1 be+ obscur$ by iron-oxide :i* we may conceive z hav+ be5 expell$ f ! spaces occupi$ by ! sph]oids4 ,! little cry/al-fragm5ts are enclos$ 9 ! sph]oids z well z 9 ! matrix1 b !re is no appe>ance ( _! hav+ s]v$ z />t+-po9ts = radiate gr[?s4 ,! flat elongat$ bodies are l ! sph]oids1 ) m]ely ! modifications impli$ 9 _! diff]5t %ape4 ,! id5tity ( ! cle> col\rless sub/ance seems to be r d\btful4 ,x is s5sibly isotropic & ( refractive p[] di/9ctly l[] ?an t ( felsp>4 ,^! *>act]s w\ld agree ) analcime1 :i* is n unkn[n z a contact-m9]al2 b x is difficult to und]/& h[ analcime1 ev5 a lime-be>+ v>iety l t ( ,plas ,newydd1#bej c\ld be =m$ 9 abundance f palagonitic mat]ial4 ,an alt]native supposition1 p]haps m probable1 is t ! cle> sub/ance is a glass1 modifi$ f its =m] nature1 especially by ! expulsion ( ! iron-oxide into ! rema9+ matrix4 ,a comp>ison is at once sugge/$ ) c]ta9 types ( ',knot5s*ief]1' b respect+ ! !rmal metamorphism ( f9e volcanic tuffs !re seems to be little or no direct in=mation4 ,footnote #bej3 ,h5sl[1 ,trans4 ,camb4 ,phil4 ,soc4 7#ahba71 vol4 i4 p4 #djh2 ,mr4 ,h>k]1 ,geol4 ,mag4 7#ahhg71 p4 #dad4 ,mr4 ,w4 ,w4 ,watts sugge/s a comp>ison ) ! hexagonal bodies figur$ by ,mr4 ,monckton 9 an alt]$ lime/one f ,/irl+%ire3 ,qu>t4 ,j\rn4 ,geol4 ,soc41 vol4 li4 p4 #dhg4 ,l5ticul> int]/ratifications ( %ale & mud/one make _! appe>ance ev5 9 ! co>s] p>ts ( ! conglom]ate1 z may be obs]v$ on ! bea* bel[ ,canna ,h\se :]e1 z %[n 9 ,fig4 #bfi1 "s %ales & tuffs 7a7 full ( ill-def9$ leaves are surm\nt$ by a conglom]ate 7b74 ,! deposition ( ?is ov]ly+ b$ ( b\ld]s has giv5 rise to "s scoop+-out ( ! f9] /rata und]nea?4 ,subsequ5tly bo? ! conglom]ate & %ales h be5 ov]spread by a /ream ( dol]ite 7c71 ! slaggy bottom ( :i* has pl\gh$ its way ?r\gh !m4 ,illu/ration3 ,fig4 #bfi4--,lava cutt+ out conglom]ate & %ale4 ,%ore bel[ ,canna ,h\se4 ,be=e discuss+ ! probable conditions "u :i* ! gr\p ( s$im5t>y deposits n[ describ$ 0 =m$1 we may conv5i5tly foll[ ! upp] conglom]ate b& ( ! ,compass ,hill1 & note ! v>iations 9 /ructure & composition :i* its outcrop pres5ts4 ,?is yell[i% conglom]ate c be trac$ along ! cliffs = m ?an a mile1 :5 x desc5ds bel[ ! sea-level at ! solit>y /ack ( ,bod an ,/l4 ,a few hundr$ y>ds fur!r we/1 :at is probably ! same b& appe>s aga9 at ! base ( ! precipice ov]la9 by prismatic basalts4 ,b ! conglom]ate1 "h only #ab feet ?ick1 is made ( mu* f9] detritus :i*1 l>gely compos$ ( volcanic mat]ial1 includes small well-r\nd$ & poli%$ pebbles ( ,torridon ,s&/one4 ,b5ea? x lies a b$ ( d>k %ale1 ) rema9s ( plants1 re/+ imm$iately on a zeolitic amygdaloid :i* plunges into ! sea4 ,! *ief int]e/ ( ?is locality is to be f\nd 9 ! %ale :i*1 in/ead ( be+ at ! top ( ! s$im5t>y gr\p1 lies at ! bottom4 ,i 0 in=m$ by ,mr4 ,a4 ,?om t leaves _h be5 obta9$ f ?is %ale2 b ,i 0 n successful 9 my se>* = !m4 ,! locality is only accessible by boat1 &1 z ! coa/ is fully expos$ to ! ,atlantic swell1 l&+ at ! place is usually difficult & (t5 impossible4 ,ab\t a mile & a half /ill fur!r we/1 :]e a =e%ore fronts ! precipice ( ,e>nagream at ! ,camas ,?>b]ni%1 a b& ( int]calat$ s$im5t>y mat]ial und]lies ! great esc>pm5t ( basalts & re/s ^u ! slaggy %eet ) ! s+ul> surface already ref]r$ to 7p4 #ahg74 ,?is b& n improbably occupies ! same plat=m z ! upp] conglom]ate ( ,compass ,hill4 ,x is only ab\t sev5 feet ?ick1 ! l[] f\r feet consi/+ ( a dull gre5 pebbly tuff or a%y s&/one1 ) small r\nd$ pieces ( ,torridon ,s&/one1 :ile ! upp] ?ree feet are =m$ ( d>k %ale ) cr[d$ b indi/9ct rema9s ( plants4 ,"h ! m usual ord] 9 ! sequ5ce ( deposition is re/or$4 ,! %ale is indurat$ & %att]y1 s t no slabs c be extract$ )\t ! use ( qu>ry+ tools4 ,illu/ration3 ,fig4 #bgj4--,section ( %ales & tuffs1 ) a conif]\s /ump ly+ betwe5 two basalt-%eets1 ,cl nam ,m>bh1 ,canna4 ,r less ?an half a mile t[>ds ! s\?1 on ! roadside at ! gully ( ,cl nam ,m>bh1 ! basalts enclose a s$im5t>y int]/ratification :i* n improbably lies on ! same horizon z ^? j describ$ along ! nor!rn %ore4 ,! relations ( ! rocks at ?is locality are %[n 9 ,fig4 #bgj4 ,a rem>kable slaggy basalt 7a7 rises into a hummock1 aga9/ :i* h be5 deposit$ "s f9e granul> tuffs 7b7 :]e( only a few in*es are visible1 t pass up into a ?9 b& ( d>k %ale 7c71 includ+ a lay] ( pebbly f]rug9\s tuff1 ) small r\nd$ pea-l pieces ( basalt1 basic pumice1 bole1 limonite1 etc4 ,at ! top ( ?is %ale an irregul> p>t+ ( coaly mat]ial 7d7 lies imm$iately "u ! slaggy base ( ! succe$+ basalt 7e74 ,x w be obs]v$ t ?is upp] lava cuts out ! %ale & ?us comes to re/ directly ^u ! l[] %eet4 ,at ! po9t :]e x beg9s to desc5d x has caught up & enclos$ a small tree-/ump 7d7 :i* /&s upright on ! coaly p>t+ & %ale4 ,?is /ump1 at ! "t ( my visit1 measur$ five in*es 9 height by ?ree in*es 9 bread?2 x _h be5 ?or\ghly *>r$ & 0 crumbl+ away on exposure1 b among ! pieces :i* ,i took f x suffici5t trace ( /ructure c be detect$ ) ! microscope to %[ ! tree to h be5 a conif]4 ,we h "h ano!r in/ance ( ! deposition ( volcanic du/ & f9e mud 9 a pool t fill$ a holl[ 9 ! lava-field4 ,aga9 we see t ! clos+ act ( s$im5tation 0 ! subsid5ce ( vegetable matt] 9 ! pool1 :i* 0 f9ally buri$ "u ano!r outfl[ ( basalt4 ,illu/ration3 ,fig4 #bga4--;,dn ,mr1 ,s&ay4 7,f a photograph by ,miss ,?om47 ,x is on ! s\!rn coa/ ( ! isle ( ,s&ay t ! high] int]calations ( s$im5t>y mat]ial among ! basalts are mo/ in/ructively display$4 ,at ! ea/]n end ( ?is isl&1 z already /at$1 ! l[e/ & co>se/ conglom]ate is visible on a sk]ry imm$iately to ! s\? ( ! headl& ,ceann an ,eile94 ,x d\btless und]lies ! ,s&ay cliffs1 b is n !re visible1 = ! basalts desc5d bel[ sea-level4 ,^! volcanic %eets h a slight incl9ation we/w>d2 h5ce 9 t direction we gradually pass into high] p>ts ( ! s]ies4 ,9 ! ,creag nam ,faoileann 7,seamews' ,crag7 & ! gully t cuts its ea/]n end1 likewise 9 ! two s+ul>ly picturesque /acks ( ,dn ,mr & ,dn ,beag 7,big & ,little ,gull ,rocks71 :i* "h rise f ! =e%ore1 two di/9ct plat=ms ( detrital mat]ial may be notic$ among ! basalts4 ,bo? ( ^! c be well se5 on ,dn ,mr1 ab\t #ajj feet high1 :i* is repres5t$ 9 ,fig4 #bga4 ,! l[] b&1 f\r or live feet ?ick1 is "h a r co>se conglom]ate :i* lies ^u a %eet ( scoriace\s basalt t ext5ds up to ! base ( ! ,creag nam ,faoileann4 ,x is directly ov]la9 by ano!r basalt1 ab\t #cj feet ?ick1 :i* dips seaw>ds & =ms a broad %elv+ plat=m1 :]eon ! tides rise & fall4 ,on ?is /ack a second co>se conglom]ate1 ab\t #aj feet ?ick1 =ms a conspicu\s b& ab\t a ?ird ( ! height f ! bottom2 x is compos$ ma9ly ( well-r\nd$ blocks ( v>i\s lavas up to #ah in*es or m 9 diamet]1 b x conta9s also pieces ( ,torridon ,s&/one4 ,x is cov]$ by ab\t #fj feet ( basalt1 :i* t[>ds ! base is some:at regul>ly column>1 b passes upw>d into ! wavy1 />*-l1 prismatic /ructure4 ,if n[ we trace ^! two int]calat$ zones ( conglom]ate along ! %ore1 we f9d !m bo? rapidly to *ange _! *>act]s & to disappe>4 ,! l[]1 ?\gh =m$ ( co>se detritus "u ! ,dn ,mr1 passes on ! opposite cliff 9 a space ( n m ?an #fj y>ds1 into f9e tuff & %ale1 ab\t six feet ?ick1 :i* become c>bonace\s at ! top :]e !y are ov]la9 by ! next basalt4 ,a hundr$ y>ds to ! ea/1 ! b& likewise consi/s ( tuffs & a%y %ales1 :i* und]lie ! basalts on ! ,dn ,beag1 & aga9 %[ ! usual coaly lay]s at ! top4 ,on ! ea/ side ( ! gully 9 ! coa/1 ab\t #afj y>ds to ! nor?-ea/ ( ,dn ,mr1 ! same b& is r$uc$ to n m ?an ?ree feet 9 ?ickness1 consi/+ *iefly ( f9e conglom]ate1 :]e9 well wat]-worn pebbles ( ,torridon ,s&/one & epidotic grit appe> among ! pr$om9ant volcanic detritus4 ,?is conglom]ate is surm\nt$ by a few in*es ( d>k c>bonace\s mud/one or %ale4 ,r\gh slaggy basalts lie above & bel[ ! b&4 ,! upp] conglom]ate dies out1 bo? t[>ds ! ea/ & ! we/1 9 ! cliff opposite to ,dn ,mr1 dw9dl+ d[n at la/ to m]ely a few pebbles betwe5 ! basalts4 ,x lies 9 a k9d ( *annel or holl[ among ^! lavas4 ,?is depression1 9 an ea/ & we/ direction1 _c be m ?an ab\t #fe y>ds broad4 ,probably /ill high] 9 ! s]ies ( basalts is ano!r int]calation ( s$im5t>y lay]s :i* may be se5 9 ! little bay to ! ea/ ( ,tallabric1 r m ?an a mile to ! we/ ( ! ,creag nam ,faoileann4 ,x re/s ^u a co>sely slaggy amygdaloid1 & is f six to t5 feet 9 ?ickness4 ,! l[] & l>g] "p ( ! deposit consi/s ( gre5i% pebbly s&/one & f9e conglom]ate1 l>gely compos$ ( basaltic detritus1 b includ+ abundant well-smoo!d & poli%$ pebbles ( ,torridon ,s&/one1 gre5 grit1 qu>tzite1 etc4 ,! /ones v>y f m]e pea-l pebbles up to pieces two or ?ree in*es long1 ! l>ge/ be+ g5]ally fragm5ts ( slag & amygdaloid :i* are less wat]-worn ?an ! s&/ones & o!r =eign +r$i5ts4 ,! upp]mo/ two or ?ree feet ( ! int]calation consi/ ( d>k c>bonace\s mud/one or %ale1 made up 9 l>ge measure ( volcanic detritus1 :i* may h be5 d]iv$ p>tly f eruptions ( f9e du/1 p>tly f subrial dis9tegration ( ! basalt-%eets4 ,"s lay]s ( ^! f9] /rata are full ( rema9s ( mu* mac]at$ plants4 ,o!r ?9 coaly int]calations h be5 obs]v$ among ! basalts ( ,canna1 "s ( :i* may possibly m>k /ill high] horizons ?an ^? n[ describ$4 ,b1 conf9+ our att5tion to ! regul> sequ5ce ( int]calations expos$ along ! ,s&ay coa/1 we f9d at lea/ f\r di/9ct plat=ms ( int]/ratifi$ s$im5t among ! plateau-basalts ( ?is di/rict4 ,ea* ( ^! m>ks a long] or %ort] int]val 9 ! outfl[ ( lava1 & po9ts to ! action ( mov+-wat] ov] ! surface ( ! lava-fields4 ,we may n[ consid] ! probable conditions "u :i* ?is int]v5tion ( aque\s action took place4 ,! idea t ! sea _h any?+ to d ) ^! conglom]ates1 s&/ones1 & %ales may be summ>ily dismiss$ f consid]ation4 ,! evid5ce t ! basalt-eruptions took place on a t]re/rial surface is entirely conv9c+1 & geologi/s are n[ agre$ ^u ?is "q4 ,exclud+ m>9e action1 we h to *oose among =ms ( fre% wat]--betwe5 lakes on ! "o h& & riv]s on ! o!r4 ,t ! ag5cy conc]n$ 9 ! transport & deposition ( ^! /rata 0 t ( a riv] may be confid5tly conclud$ on ! foll[+ gr\nds3-- #a4 ,! l>ge size & roll$ %ape ( ! b\ld]s 9 ! conglom]ates4 ,to move blocks sev]al tons 9 weight1 & n only to move !m b to we> !m into m or less r\nd$ =ms1 mu/ h requir$ ! op]ation ( /rong curr5ts ( wat]4 ,! co>se detritus int]calat$ among ! basalts is q comp>able to ! %+le ( a mod]n riv]1 :i* desc5ds ) rapidity & 9 ample volume f a range ( hills4 #b4 ,! evid5ce t ! mat]ials ( ! conglom]ates are n entirely local1 b include a m>k$ proportion ( =eign /ones4 ,! pro(s ( transport are admirably exhibit$ by pieces ( ,torridon ,s&/one1 epidotic grit1 qu>tzite1 & o!r h>d rocks none ( :i* occur 9 situ except at "s di/ance f ,canna4 ,^! /ones are (t5 n m]ely r\nd$1 b s well smoo!d & poli%$ z to %[ t !y mu/ h be5 roll$ along = "s consid]able "t 9 wat]4 #c4 ,! l5ticul> "* & rapid li?ological v>iations ( ! /rata1 bo? lat]ally & v]tically4 ,! co>se conglom]ates die out z !y are foll[$ along _! outcrop & pass into f9] s$im5t4 ,!y seem to occur 9 irregul> banks1 :i* may n be m ?an #bjj feet broad1 l ! %+le-banks ( a riv]4 ,! co>s] s$im5t g5]ally lies 9 ! l[] "p ( ! s$im5t>y gr\p4 ,b cases may be obs]v$1 su* z t %[n 9 ,fig4 #bfi1 :]e f9e s$im5t1 laid d[n ^u ! bottom conglom]ate1 has subsequ5tly be5 ov]spread by ano!r inroad ( co>se %+le4 ,su* alt]nations are n difficult to und]/& if !y are look$ ^u z indicat+ ! successive floods & quiet] int]vals ( a riv]4 ,= ^! reasons ,i reg>d ! plat=ms ( s$im5t>y mat]ials int]calat$ among ! basalts ( ,canna & ,s&ay z ! successive flood-pla9s ( a riv] :i*1 l ! riv]s t trav]se ! lava-des]ts ( ,icel&1 fl[$ p]haps 9 _m sep>ate *annels across ! basalt-fields ( ! ,inn] ,hebrides1 & 0 liable to h its c\rse %ift$ f "t to "t by fre% volcanic eruptions4 ,t ?is riv] came f ! ea/ or nor?-ea/ & _h its s\rce among ! ,we/]n ,highl&s ( ,inv]ness-%ire1 may be inf]r$ f ! nature ( ! /ones :i* x has c>ri$ = #cj miles or m along its b$4 ,& t x cross$ 9 its c\rse ! tract ( ,torridon ,s&/one1 ( :i* a portion /ill rema9s 9 ,rum1 is manife/ f ! abundance ( ! fragm5ts ( t =mation 9 ! conglom]ates4 ,) ! rem>kable exception ( ! section on ,dn ,beag1 to be imm$iately ref]r$ to1 no trace ( any erod$ *annel ( ?is riv] ?r\gh ! lavas ( ! great volcanic pla9 has be5 pres]v$4 ,possibly frequ5t invasions ( its b$ by /reams ( basalt f diff]5t v5ts h9d]$ x f rema9+ long en\gh 9 "o c\rse to erode any?+ l a gorge or canon4 ,b1 9 any case1 ! ma9 *annel ( ! riv] probably lay r to ! ea/ ( ! pres5t isl&s ( ,canna & ,s&ay1 on gr\nd :i* is n[ cov]$ by ! sea4 ,! banks or %eets ( b\ld]-conglom]ate und\bt$ly %[ :]e its curr5t swept ) great =ce ov] ! lava-pla91 b ! mann] 9 :i* ^! co>s] mat]ials are s (t5 cov]$ ) f9e silt sugge/s t ! s$im5t>y mat]ials n[ visible 7 r deposit$ on ! l[ gr\nds ov] :i* ! /eam ru%$ 9 times ( flood4 ,pools ( wat] w\ld (t5 be left aft] su* inundations1 & 9 ^! depressions silt w\ld gradually accumulate1 p>tly c>ri$ 9 susp5sion by ! riv]1 p>tly wa%$ 9 by ra91 :ile drift-wood t f\nd its way into ^! eddies1 & leaves bl[n into !m f ! trees & %rubs ( ! surr\nd+ c\ntry1 w\ld rema9 = "s "t afloat & w\ld be ! la/ ( ! detritus to s9k to ! bottom4 ,h5ce1 no d\bt1 ! c>bonace\s "* ( ! h>d5$ silt 9 ! upp] "p ( ea* int]calation ( s$im5t4 ,if we 7 to look ^u ! volcanic mat]ials 9 ! conglom]ates z d]iv$ f ! subrial dis9tegration ( ! fields ( basalt1 we %\ld be compell$ to admit a v l>ge am\nt ( erosion ( ! surface ( ! volcanic pla9 dur+ ! p]iod :5 ! riv] fl[$ ov] t tract4 ,x w\ld be necess>y to suppose n only t !re 0 a consid]able ra9fall1 b t ! diff]5ces ( temp]ature1 ei!r f day to night1 or f summ] to w9t]1 7 s great z to split up ! lavas at ! surface1 9 ord] to provide ! riv] ) ! blocks :i* x has roll$ into r\nd$ b\ld]s4 ,i d n ?9k1 h[ev]1 t su* a d$uction w\ld be s\nd4 ,if we comp>e ! mat]ials t h fill$ up ! l>ge eruptive v5t at ! ea/ end ( ,canna 7to be aft]w>ds describ$7 ) ! great majority ( ! blocks 9 ! co>se conglom]ates1 we _c fail to note _! /rong resemblance4 ,! abundance ( lumps ( slaggy lava 9 ! riv]-%+le corresponds ) _! pr$om9ance 9 ! agglom]ate ( ! v5t4 ,! b\ld]s ( basalt1 dol]ite1 & &esite :i* cr[d ! conglom]ates ne$ n h be5 d]iv$ f ! action ( atmosph]ic wa/e on ! lava-fields1 b might q well h be5 ma9ly suppli$ by ! demolition ( volcanic cones ( fragm5tal mat]ials4 ,illu/ration3 ,fig4 #bgb4--,view ( ! ,dn ,beag1 ,s&ay1 se5 f ! s\?4 7,f a ,photograph by ,miss ,?om47 ,t su* has really be5 ! *ief s\rce ( ! blocks 9 ! conglom]ates ,i _c d\bt4 ,at ! ea/ end ( ,canna we actually detect a volcanic cone1 p>tly wa%$ d[n & ov]la9 by a pile ( riv]-%+le4 ,!re 7 probably _m su* m\nds ( slag & /ones along l9es ( fissure all ov] ! lava-fields4 ,! riv] 9 its w9d+ c\rse might come ^u "o cone aft] ano!r1 & dur+ times ( flood1 or :5 its wat]s bur/ ?r\gh any tempor>y b>ri] creat$ by volcanic op]ations x w\ld attack ! slopes ( loose mat]ial & sweep _! detritus onw>d4 ,at ! same "t1 ! curr5t w\ld c>ry =w>d its own natural burd5 ( f>-transport$ s$im5t1 & h5ce on its flood-pla9s1 buri$ & pres]v$ "u %eets ( basalt1 we f9d abundant pebbles ( ! old ,highl& rocks :i* x _h borne across ! :ole bread? ( ! basaltic l[l&4 ,b ! de/ruction ( volcanic cones 0 probably n ! only s\rce ( ! basaltic detritus 9 ! conglom]ates ( ,canna & ,s&ay4 ,i h %[n t ^! conglom]ates pass lat]ally into tuffs1 & are sometimes und]la91 sometimes ov]la91 ) simil> mat]ial4 ,x is q obvi\s t _! deposition 0 contemporane\s ) volcanic action 9 ! imm$iate neighb\rhood1 & t at lea/ "p ( _! f9] s$im5t 0 obta9$ directly f volcanic explosions4 ,9 w&]+ ov] ! coa/-sections ( ^! co>se deposits1 ,i h be5 impress$ ) ! enorm\s size ( _m ( ! /ones1 _! resemblance to ! eject$ blocks ( ! agglom]ate1 & ! di/9ction t may sometimes be made ) m or less cle>ness betwe5 _! r angul> =ms & ! m r\nd$ & some:at wat]-worn aspect ( ! o!r b\ld]s4 ,x seems to me n improbable t "s ( ! rem>kably co>se masses ( un/ratifi$ conglom]ate 9 ,canna ,h>b\r consi/ l>gely ( eject$ blocks f ! adjac5t v5t4 ,illu/ration3 ,fig4 #bgc4--,view ( ,dn ,beag1 ,s&ay1 f ! nor?4 ,! isl& ( ,rum 9 ! di/ance4 7,f a ,photograph by ,miss ,?om47 ,! only in/ance :i* ,i h obs]v$ ( erosion ( ! basalt contemporane\s ) ! op]ations ( ! riv] t spread out ?is conglom]ate is to be f\nd 9 ! /rik+ /ack ( ,dn ,beag already allud$ to4#bea ,?is extraord9>y monum5t ( geological hi/ory =ms an outly+ obelisk :i* rises f ! plat=m ( ! %ore to a height ( ab\t #gj feet4 ,se5 f ! s\?-we/1 x appe>s to consi/ entirely ( b$d$ basalt re/+ on "s /ratifi$ tuff & %ale :i* int]v5e betwe5 ^! lavas & t ( ! broad plat=m ( basalt on :i* ! obelisk /&s4 ,on t side x pres5ts no ess5tial diff]5ce f ! /ructure ( ! ,dn ,mr to ! we/1 save t ! l[] conglom]ate ( t outli] is "h repres5t$ by f9e s$im5t1 & ! upp] conglom]ate is want+4 ,! g5]al aspect ( ?is s\?-we/]n front ( ! /ack is %[n 9 ,fig4 #bgb4 ,if1 h[ev]1 we approa* ! rock f ! coa/-gully to ! nor?1 we =m a v diff]5t impression ( its /ructure4 ,x !n appe>s to consi/ *iefly ( conglom]ate ) a capp+ ( basalt on ! top 7,fig4 #bgc74 ,n until a close scrut9y is made ( ! ea/]n & we/]n faces ( ! column d ! true /ructure & hi/ory ( ?is s+ul> piece ( topography become app>5t4 ,footnote #bea3 ,?is p9nacle ( rock is ref]r$ to by ,maccullo* 9 8 acc\nt ( ,canna1 & is figur$ 9 ,plate xix4 ,fig4 #c ( 8 "w already cit$4 ,b nei!r 8 description nor 8 draw+ conveys any idea ( ! real /ructure ( ! rock4 ,illu/ration3 ,fig4 #bgd4--,section ( ea/]n front ( ,dn ,beag4 a1 ,v %aggy amygdaloidal basalt2 b1 %ales & tuff2 c1 slaggy & jo9t$ basalts2 d1 conglom]ate2 e1 prismatic basalt4 ,! dott$ l9es indicate ! suppos$ =m ( ! rav9e4 ,on ! ea/]n front1 ! section repres5t$ 9 ,fig4 #bgd is expos$4 ,at ! bottom1 =m+ ! p$im5t ( ! column1 lies a %eet ( slaggy & vesicul> or amygdaloidal basalt 7a71 :i* %elves g5tly 9 a s\?-we/]ly direction into ! sea4 ,! l[e/ b& 7b7 9 ! /ructure ( ! /ack is a ?9 gr\p ( lilac1 br[n1 & gre5 %ale & volcanic mud/one or tuff1 :i* encloses pieces ( conif]\s wood1 & becomes m>k$ly c>bonace\s 9 its upp]mo/ lay]s4 ,above ^! /rata on ! s\? front comes ! pile ( b$d$ basalts 7c7 ) _! slaggy l[] & upp] surfaces4 ,b z we foll[ !m r\nd ! ea/ side1 we f9d !m to be abruptly cut (f by a mass ( conglom]ate 7d74 ,t ! v]tical junction-l9e is n a fault is spe$ily asc]ta9$4 ,! l[] plat=m ( slaggy basalt runs on unbrok5 "u bo? %ales & conglom]ate4 ,moreov]1 ! l9e ( meet+ ( ?is conglom]ate ) ! basalts t ov]lie ! %ales is n a clean-cut /raight wall1 b displays projections & recesses ( ! igne\s rocks1 r\nd & into :i* ! mat]ials ( ! conglom]ate h be5 deposit$4 ,! pebbles may be se5 fill+ up little crevices1 pass+ "u ov]hang+ l$ges ( ! basalts1 & %>ply truncat+ l9es ( scoriace\s /ructure 9 ^! rocks4 ,! same relations may be obs]v$ on ! we/ front ( ! /ack4 ,!re ! a%y %ales & tuffs are %>ply cut out by ! conglom]ate1 :i* wraps r\nd & und]lies a project+ cornice ( ! slaggy bottom ( ! basalt t re/s on ! /ratifi$ b& 7,fig4 #bge74 ,illu/ration3 ,fig4 #bge4--;,enl>g$ ,section on ! we/]n side ( ,dn ,beag4 a1 amygdaloid2 b1 tuff2 c1 a%y %ales2 d1 lay] ( coaly %ale2 e1 amygdaloidal basalts conglom]ate4 ,! conglom]ate is rudely /ratifi$ horizontally1 its b$d+ be+ be/ %[n by occasional p>t+s ( gre5i% s&/one4 ,x consi/s ( well-r\nd$1 poli%$1 & wat]-worn /ones1 *iefly ( memb]s ( ! volcanic s]ies--basalts1 & dol]ites1 bo? compact & amygdaloidal or slaggy--b ) a conspicu\s admixture ( ,torridon ,s&/one1 gneiss1 grey granite1 grit & diff]5t s*i/s4 ,! co>se/ "p ( ! deposit lies t[>d ! bottom :]e ! volcanic blocks1 "s ( !m be+ six & eight feet 9 diamet]1 may h orig9ally fall5 f ! basalts aga9/ :i* ! conglom]ate n[ reposes4 ,! f>-transport$ /ones are also ( consid]able size1 pieces ( granite & gneiss frequ5tly exce$+ a foot 9 l5g?4 ,! well-r\nd$ pebbles ( =eign mat]ials h be5 wa%$ into ! int]/ices betwe5 ! l>ge volcanic blocks4 ,x is1 ,i ?9k1 tol]ably cle> t ! wall ( basalt aga9/ :i* ?is conglom]ate has be5 laid d[n is "o ( erosion4 ,! b$s ( basalt h "h be5 tr5*$ by "s ag5t :i* has likewise scoop$ out ! s(t und]ly+ %ales1 & ev5 cut !m away f "u _! protect+ cov] ( basalt4 ,!re c be little hesitation 9 reg>d+ ?is ag5t z a wat]-c\rse1 :i* = "s consid]able int]val ( "t cont9u$ to dig its *annel ?r\gh ! h>d basalts4 ,!re is n room en\gh betwe5 ! basalt-wall ( ,dn ,beag & ! opposite cliffs ( ! %ore 7:]e no trace ( ?is conglom]ate is to be se57 = any l>ge /ream to h f\nd its way4 ,i d n !re=e seek to id5tify ?is relic ( an anci5t wat]way ) ! *annel ( ! ma9 riv] :i* deposit$ ! conglom]ate b&s ( ,canna & ,s&ay4 ,m probably x 0 ei!r a m]e torr5tial *asm1 or a tribut>y /ream dra9+ a c]ta9 "p ( ! volcanic plateau & all[$ to reta9 its *annel long en\gh to be able to erode x to a dep? ( ne>ly #ej feet4 ,erosion _h rea*$ d[n ?r\gh ! und]ly+ tuffs to ! slaggy basalt bel[1 b be=e x _h made any progress 9 t %eet its op]ations 7 br\ght to an end at ?is locality by ! floods t swept 9 ! co>se %+le1 & by ! subsequ5t /ream ( basalt ( :i* a m]e outly+ fragm5t n[ =ms ! upp] ?ird ( ! /ack 7e1 ,fig4 #bgd74 ,t ! rav9e or gully ( ,dn ,beag probably lay )9 ! rea* ( ! floods ( ! ma9 riv]1 may be inf]r$ f ! numb] & size ( ! f>-transport$ rocks 9 its conglom]ate4 ,x 0 fill$ up gradually1 b ! conditions ( deposition rema9$ little *ang$ dur+ ! process1 except t ! l>ge/ blocks ( rock 7 swept into ! *asm 9 ! e>li] "p ( its hi/ory1 :ile mu* small] & m wat]-worn %+le 7 introduc$ t[>ds ! close4 ,d5udation1 :i* has p]=m$ su* m>vels 9 ! topography ( ! ,we/ ( ,scotl& s9ce old] ,t]ti>y "t1 has "h oblit]at$ e trace ( ?is anci5t gully1 save ! little fragm5t ( "o ( ! walls :i* survives 9 ! /ack ( ,dn ,beag4 ,:5 9 ! c\rse ( c5turies ?is picturesque obelisk %all h yield$ to ! action ( ! elem5ts1 ! la/ leaflet ( "o ( ! mo/ int]e/+ *apt]s 9 ! geological hi/ory ( ! ,inn] ,hebrides w h be5 de/roy$4 ,! "q naturally arises--,:at 0 ! subsequ5t hi/ory ( ! riv] :i* has left s _m records ( its floods entomb$ among ! basalts ( ,canna & ,s&ay8 ,9 p>ticul>1 c any connection be trac$ or plausibly conjectur$ betwe5 x & ! riv]-b$ pres]v$ "u ! ,scuir ( ,eigg8 ,to ?is "q ,i %all return aft] ! evid5ce = ! exi/5ce & date ( ! latt] /ream has be5 laid be=e ! read]4 ,9 ! *a9 ( ! ,inn] ,hebrides1 brok5 z x is 9 outl9e & v>i$ 9 its types ( sc5]y1 !re is no object m /rik+ ?an ! isl& ( ,eigg4 ,?\gh only ab\t five miles long & f a mile & a half to ?ree miles & a half broad1 & n[h]e rea*+ a height ( s mu* z #acjj feet1 ?is little isl&1 f ! s+ul>ity ( "o feature ( its surface1 =ms a conspicu\s & famili> l&m>k4 ,view$ 9 ! simple/ way1 ,eigg may be reg>d$ z consi/+ ( an isolat$ "p ( ! basaltic plateau :i*1 in/ead ( =m+ a roll+ tablel& or a *a9 ( hills ) t]rac$ sides1 z 9 ,antrim1 ,mull & ,skye1 has be5 s tilt$ t1 :ile x caps a l(ty cliff ab\t #ajjj feet above ! waves at ! nor? end1 x slopes g5tly along ! l5g? ( ! isl& to ! s\? end4 ,9 its s\!rn half1 h[ev]1 ! gr\nd rises1 ow+ to ! pres]vation ( an upp] mass ( lavas1 :i* d5udation has remov$ f ! nor!rn half4 ,on ?is ?ick] "p ( ! plateau /&s ! di/+ui%+ feature ( ! isl&1 ! /range fanta/ic ridge ( ! ,scuir1 :i*1 se5 f ! nor? or s\?1 looks l a long /eep hill-cre/1 end+ 9 a %>p precipice on ! ea/4 ,view$ f ! ea/1 ?is precipice is se5 to be ! end ( a huge m\nta9-wall1 :i* rises v]tically above ! basalt-plateau to a height ( m ?an #cej feet4 ,! accompany+ map 7,fig4 #bgf7 %[s t ! ridge ( ! ,scuir corresponds ) ! area occupi$ by a mass ( pit*/one1 & t :ile ! basaltic rocks cov] ! :ole ( ! re/ ( ! s\!rn half ( ! isl&1 !y gradually rise t[>ds ! nor?1 successive memb]s ( ! ,jurassic s]ies mak+ _! appe>ance until1 at ! cliffs ( ,dunan ,?alasgair1 ! latt] cov] ! great] "p ( ! surface1 & leave ! volcanic rocks z a m]e /ripe capp+ ! cliffs4 ,9 ! section 7,fig4 #bgg7 ! g5]al /ructure ( ! isl& is repres5t$4 ,illu/ration3 ,fig4 #bgf4--;,geological ,map ( ! ,isl& ( ,eigg4 ,p1 ,pit*/one-lava ( ! ,scuir2 ,r1 old riv] gravel "u pit*/one2 p p1 small ve9s ( ,pit*/one2 b b1 dykes1 ve9s & %eets ( intrusive basalt2 ! %ort black l9es runn+ nor?-we/ & s\?-ea/ are basalt dykes2 f f1 granophyre sills2 ,d1 b$d$ basalts ) occasional tuffs2 ,f1 &esite2 #a1 #b1 #c1 #d1 clays1 %ales1 s&/ones1 lime/ones1 etc4 7,jurassic72 xx1 ,lo* ,be9n ,tighe2 x1 ,lo* a ,bhealai*4 -- ,g5]al dip ( ! rocks4 ,illu/ration3 ,fig4 #bgg4--,section ( ! geological /ructure ( ! ,isl& ( ,eigg4 ,p1 ,pit*/one-lava ( ,scuir2 c1 anci5t riv]-gravel2 p p1 pit*/one ve9s2 f f1 intrusive granophyre1 etc42 b b1 dol]ite & basalt dykes & ve9s2 ,b1 intrusive dol]ite & basalt-%eets2 ,d1 b$d$ dol]ites & basalts2 ,f1 &esite b$2 #a-d1 ,jurassic rocks4 ,9 ,eigg ! fragm5t ( ! basalt-plateau :i* has be5 pres]v$1 re/s uncon=mably on successive plat=ms ( ! ,jurassic =mations4 ,its compon5t %eets ( lava rise 9 cliffs ar\nd ! great] "p ( ! isl&4 ,z !y dip g5tly s\?w>ds _! l[] memb]s are se5 along ! nor!rn & ea/]n %ores1 :ile on ! s\?-we/ side _! high] portions are expos$ 9 ! l(ty precipices :i* !re plunge v]tically into ! sea4 ,! total ?ickness ( ! volcanic s]ies may "h be ab\t #aajj feet4 ,! rocks consi/ ( ! usual types--black1 f9e-gra9$1 column> & amorph\s basalts1 m co>sely cry/all9e dol]ites1 dull e>?y amygdaloids ) r$ p>t+s1 & occasional ?9 b&s ( basalt-conglom]ate or tuff4 ,! individual b$s range 9 ?ickness f #bj to #ej or #fj feet4 ,?\gh !y seem q cont9u\s :5 look$ at f ! sea1 yet1 on clos] exam9ation1 !y are f\nd n unfrequ5tly to die out1 ! place ( "o b$ be+ tak5 by ano!r1 or ev5 by m ?an "o1 9 cont9uation ( ! same horizon4 ,! only m>k$ petrographical v>iety :i* occurs among !m is a light-col\r$ b& :i* /&s out conspicu\sly among ! d>k] ord9>y %eets ( ! esc>pm5t on ! ea/ side ( ! isl&4 ,! microscopic *>act]s ( ?is rock %[ x to belong to ! same s]ies ( highly felspa?ic1 &esitic1 or tra*itic lavas z ! pale gr\p ( ,b5 ,m1 9 ,mull4 ,x is /rongly vesicul>1 & ! cells are 9 "s p>ts s flatt5$ & elongat$ z to imp>t a k9d ( fissile texture to ! rock4 ,!re c be no d\bt t ?is b& is a true lava1 & t x 0 p\r$ out dur+ ! accumulation ( ! basalt-plateau4 ,x supplies an int]e/+ example ( ! int]calation ( a light] & less basic lava among ! ord9>y heavy basic basalts & dol]ites4 ,t feature ( ! isl& ( ,eigg :i* r5d]s x s rem>kable & conspicu\s an object on ! we/ coa/ is ! long ridge ( ! ,scuir4 ,ris+ g5tly f ! valley :i* crosses ! isl& f ,laig ,bay to ! ,h>b\r1 ! basaltic plateau asc5ds s\?-we/w>ds 9 a succession ( t]races1 until along its upp] "p x =ms a long cre/1 f #ijj to #ajjj feet above ! sea1 to :i* x desc5ds on ! o!r or s\?-we/ side1 fir/ by a %>p slope1 & !n by a range ( precipices4 ,along ! wat]%$ ( ?is cre/ runs1 9 a graceful d\ble curve1 ! abrupt ridge ( ! ,scuir1 t]m9at+ on ! nor?-we/ at ! edge ( ! great sea-cliff 7#ige feet71 & end+ (f on ! s\?-ea/ 9 t /range well-kn[n m\nta9-wall 7#abgb feet high7 :i* rises 9 a %e] cliff ne>ly #cjj feet above ! basalt-plateau on ! "o side & m ?an #djj feet on ! o!r 7,fig4 #bgh74 ,! total l5g? ( ! ,scuir ridge is two miles & a qu>t]1 its greate/ bread? #aebj1 its lea/ bread? #cej feet4 ,its surface is v irregul>1 ris+ into m9or hills & s9k+ into rock-bas9s1 ( :i* n9e are small t>ns1 besides /ill small] pools1 :ile six o!rs1 also fill$ ) wat]1 lie p>tly on ! ridge & p>tly on ! basaltic plateau4 ,no "o1 inde$1 :o looks on ! ,scuir f bel[1 & notes h[ ev5ly x re/s ^u ! basalt-plateau1 w\ld be prep>$ = s rugg$ a l&scape z t :i* meets 8 eye ev]y:]e along ! top ( ! ridge4 ,two m9or arms project f ! ea/ side ( ! ridge2 "o ( ^! =ms ! r\nd$ hill call$ ,be9n ,tighe 7#ifh feet71 ! o!r ! hill ( ,a *or ,bhe9n4 ,illu/ration3 ,fig4 #bgh4--,view ( ! ,scuir ( ,eigg f ! ea/4 ,s+ul> z ! ,scuir ( ,eigg is1 reg>d$ m]ely z "o ( ! l&m>ks ( ! ,hebrides1 its geological hi/ory is n less peculi>4 ,! natural impression :i* arises 9 ! m9d :5 ?is m\nta9 comes into view = ! fir/ "t is1 t ! huge wall is "p ( a great dyke or intrusive mass :i* has be5 ?ru/ ?r\gh ! old] rocks4#beb ,x 0 n until aft] "s "t t ! influ5ce ( ?is fir/ impression pass$ (f my own m9d1 & ! true /ructure ( ! mass became app>5t4 ,footnote #beb3 ,hay ,cunn+ham rem>ks3--,9 reg>d to ! relations ( ! pit*/one-porphyry ( ! ,scuir & ! trap-rocks ) :i* x is connect$1 x c1 aft] a mo/ c>eful exam9ation ar\nd ! :ole mass1 be confid5tly ass]t$ t x exi/s z a great ve9 :i* has be5 erupt$ ?r\gh ! o!r ,plutonic rocks--?us agree+ 9 age ) all ! o!r pit*/ones ( ! isl&4 ,maccullo* leaves u to inf] t he reg>d$ ! rock ( ! ,scuir to be regul>ly int]/ratifi$ ) ! highe/ b$s ( ! dol]ite s]ies 7,we/]n ,isles1 i4 p4 #ebb74 ,hugh ,mill] speaks ( ! ,scuir ( ,eigg z re/+ on ! rema9s ( a pro/rate =e/4--,cruise ( ! ,betsy1 p4 #cb4 ,! ridge ( ! ,scuir1 pres5t+ z x does s /rong a topographical contra/ to ! gre5 t]rac$ slopes ( ! plateau-basalts on :i* x re/s1 consi/s ( "s v di/9ct b&s ( black & grey lava1 long kn[n z pit*/one-porphyry4 ,to ! nature & hi/ory ( ^! rocks ,i %all return aft] we h consid]$ a rem>kable b$ ( conglom]ate :i* lies bel[ !m4 ,on ! l[] or s\!rn side ( ! ridge ! bottom ( ! pit*/one1 dipp+ into ! hill1 is expos$ on ! ro( ( a small cave :]e ! ends ( its columns =m a polygonal reticulation4 ,x is !re se5 to repose ^u a b$ ( breccia or conglom]ate1 hav+ a pale-yell[ or grey felspa?ic matrix l ! m decompos+ p>ts ( ! grey devitrifi$ p>ts ( ! pit*/one4 ,?r\gh ?is deposit are disp]s$ great numb]s ( angul> & subangul> pieces ( pit*/one1 "s ( :i* h a /rip$ texture4 ,fragm5ts ( basalt1 r$ 7,torridon7 s&/one1 & o!r rocks are r>e2 & ! b$ sugge/s ! idea t x is a k9d ( brecciat$ base or floor ( ! ma9 pit*/one mass4 ,a simil> rock is f\nd along ! bottom ( ! pit*/one on bo? sides ( ! ridge 7c1 9 ,fig4 #bgi74 ,"h & !re :]e ?is breccia is only a y>d or two 9 ?ickness1 x consi/s ( subangul> fragm5ts ( ! v>i\s dol]ites & basalts ( ! neighb\rhood1 toge!r ) pieces ( r$ s&/one1 qu>tzite1 clay-slate1 etc4 ,! matrix is 9 "s places a mass ( h>d basalt debris2 9 o!rs x becomes m calc>e\s1 pass+ into a s&/one or grit 9 :i* *ips & angul> or irregul>-%ap$ pieces ( conif]\s wood are abundant4#bec ,a little fur!r ea/1 beyond ! base ( ! ,scuir1 a pat* ( simil> breccia is se51 b ) ! /ones mu* m r\nd$ & smoo!d4 ,?is outli] re/s aga9/ ! d5ud$ ends ( ! basalt-b$s =m+ ! side ( ! hill4 ,its int]e/ arises f ! evid5ce x af=ds ( ! prolongation ( ! deposit ea/w>d1 & consequ5tly ( ! =m] ext5sion ( ! precipice ( ! ,scuir consid]ably beyond its pres5t front4 ,footnote #bec3 ,! microscopic /ructure ( ?is wood 0 briefly describ$ by ,)am 7,fossil ,vegetables1 p4 #cg71 & two magnifi$ repres5tations 7 giv5 to %[ its conif]\s "*4 ,l9dley & ,hutton fur!r describ$ x 9 _! ,fossil ,flora1 nam+ x ,p9ites eigg5sis1 & reg>d+ x z belong+ to ! ,oolitic s]ies ( ! ,hebrides--an inf]5ce f\nd$ p]haps on ! errone\s /atem5t ( ,)am to t effect4 ,william ,nicol correct$ t /atem5t by %[+ t ! wood-fragm5ts occurr$1 n among ! lias rocks1 b among ! debris ( ! pit*/one 7,ed94 ,new ,phil4 ,j\rnal1 xviii4 p4 #aed74 ,hay ,cunn+ham1 9 ! pap] already cit$1 /ates t ! fossil wood really lies 9 ! pit*/one itself6 ,! actual position ( ! wood1 h[ev]1 9 ! breccia & conglom]ates und]ly+ ! pit*/one is beyond all dispute4 ,i h myself dug x out ( ! b$4 ,! geological horizon assign$ to ?is conif]1 on acc\nt ( its suppos$ occurr5ce among ,oolitic rocks1 be+ f\nd$ on error1 no great] weight c be atta*$ to ! id5tification ( ! plant ) an ,oolitic species4 ,our k ( ! specific v>ieties ( ! microscopic /ructure ( anci5t vegetation is h>dly precise en\gh to w>rant u 9 def9itely fix+ ! horizon ( a plant m]ely f ! exam9ation ( ! m9ute texture ( a fragm5t ( its wood4 ,f ! int]nal organization ( ! ,eigg p9e1 !re is no evid5ce t ! fossil is ( ,jurassic age4 ,f ! position ( ! wood above ! dol]ites & und]nea? ! pit*/one ( ! ,scuir x is absolutely c]ta9 t ! plant is n ( ,jurassic b ( ,t]ti>y date4 ,x is at ! extreme nor?-we/]n extremity ( ! pit*/one ridge1 h[ev]1 t ! mo/ rem>kable exposure ( ?is int]calat$ detrital b& is n[ to be se54 ,sweep+ along ! cre/ ( ! plateau ! ridge rea*es ! edge ( ! great precipice ( ,bideann ,boidhea*1 by :i* its end is truncat$1 s z to lay op5 a section ( ! gravelly deposit along :i* ! pit*/one fl[$4 ,! accompany+ diagram 7,fig4 #bgi7 repres5ts ! natural section !re expos$4 ,ris+ ov] ea* o!r 9 successive b$s1 ) a h>dly p]ceptible s\!rly dip ( #b1 ! %eets ( basalt =m a mural cliff ab\t #gjj feet high4 ,! b$d$ "* ( ^! rocks & _! alt]nations ( compact1 column>1 amorph\s & amygdaloidal b$s are "h /rik+ly se54 ,!y are trav]s$ by ve9s & dykes ( an exce$+ly close-gra9$1 sometimes almo/ fl9ty1 basalt4 ,b ! conspicu\s feature ( ! cliff is ! holl[ :i* has be5 worn out ( ^! rocks1 & :i*1 aft] be+ p>tially fill$ ) co>se conglom]ate1 has be5 buri$ "u ! huge pit*/one mass ( ! ,scuir4 ,! conglom]ate consi/s ( wat]-worn fragm5ts1 *iefly ( dol]ite & basalt1 b ) "s also ( ! :ite ,jurassic s&/ones1 imb$d$ 9 a compact$ s& d]iv$ f ! wa/e ( ! old] volcanic rocks4 ,! grey devitrifi$ b&s 9 ! pit*/one1 s conspicu\s at ! ea/ end ( ! ,scuir1 "h disappe> & leave ! conglom]ate cov]$ by "o huge ov]ly+ mass ( glassy pit*/one4 ,illu/ration3 ,fig4 #bgi4--,natural ,section at ! ,cliff ( ,bideann ,boidhea*1 nor?-we/ end ( ! ,scuir ( ,eigg4 a a1 ,b$d$ dol]ites & basalts2 b1 basalt dykes & ve9s2 c1 anci5t riv]-b$ fill$ ) conglom]ate2 p1 pit*/one ( ! ,scuir4 ,if any d\bt c\ld arise z to ! orig9 ( ! mass ( detritus expos$ "u ! pit*/one at ! ea/ end ( ! ,scuir x w\ld be dispell$ by ! section at ! we/ end1 :i* %[s ) unmi/akable cle>ness t ! conglom]ate is a fluviatile deposit & lies 9 ! actual *annel ( ! anci5t riv] :i* 0 erod$ out ( ! basalt plateau1 & 0 subsequ5tly seal$ up by /reams ( pit*/one-lava4 ,an exam9ation ( ! fragm5ts ( rock f\nd 9 ! conglom]ate af=ds "h1 z 9 ,canna & ,s&ay1 "s indication ( ! direction 9 :i* ! riv] fl[$4 ,! occurr5ce ( pieces ( r$ s&/one1 :i* no "o :o kn[s ,we/-,highl& geology c fail to recognize z ( ,torridonian d]ivation1 at once makes x cle> t ! high] gr\nds f :i* !y 7 borne probably lay to ! nor? or nor?-ea/4 ,! fragm5ts ( :ite s&/one may also h be5 d]iv$ f ! same qu>t]1 = ! ?ick ,jurassic s]ies ( ,eigg once ext5d$ fur!r 9 t direction4 ,! pieces ( qu>tzite & clay-slate be> simil> te/imony to an ea/]n or nor?-ea/]n s\rce4 ,9 %ort1 !re seems e probability t ?is old ,t]ti>y riv] fl[$ ?r\gh a =e/-clad region1 ( :i* ! r$ ,torridon m\nta9s ( ,ross-%ire1 ! :ite s&/one cliffs ( ,raasay & ,skye1 & ! qu>tzite & s*i/ upl&s ( ,we/]n ,inv]ness-%ire are b fragm5ts1 t x pass$ ov] a wide & long tract ( ! volcanic plateau1 & cont9u$ to fl[ long en\gh to be able to c>ve out = itself a *annel on ! surface ( ! basalt4 ,its c\rse across :at is n[ ! isl& ( ,eigg took a some:at nor?-we/]ly direction1 probably guid$ by inequalities on ! surface ( ! lava-pla94 ,x is !re m>k$ by ! w9d+ ridge ( ! ,scuir1 ! pit*/one ( :i* fl[$ into ! riv]-b$ & seal$ x up4 ,sev]al m9or spurs1 :i* project f ! ea/]n side ( ! ma9 ridge1 %[ ! positions ( small tribut>y rivulets t ent]$ ! pr9cipal *annel f ! slopes ( ! basaltic tablel&4 ,"o ( ^!1 on ! s\?-ea/ side ( ! hill call$ ,corv51 mu/ h be5 a gully 9 ! basalt ) a rapid or wat]fall4 ,! pit*/one has fl[$ into x1 & "s ( ! r\nd$ pebbles t lay 9 ! *annel ( ?is vani%$ brook may /ill be ga!r$ :]e ! degradation ( ! pit*/one has once m expos$ !m to ! light4 ,t ! ,eigg riv] "h fl[$ 9 a we/]ly direction may be inf]r$ f ! angle at :i* ! b$s ( ! small tribut>ies meet ! ma9 /ream1 & also f ! fact t ! old riv]-b$ at ! ea/ end ( ! ,scuir is consid]ably high] ?an at ! we/ end4 ,sev]al features 9 ! geological /ructure ( ?is locality s]ve to impress on ! m9d ! great lapse ( "t repres5t$ by ! erosion ( ! riv]-*annel ( ,eigg4 ,?us at ! n>r[e/ po9t ( ! pit*/one ridge1 ne> ! little ,lo* a' ,bhealai*1 ! bottom ( ! glassy lava is ab\t #bjj feet above its base on ! s\? side1 s t ! valley cut out ( ! plateau-basalts mu/ h be5 m ?an #bjj feet deep4 ,ev5 ! little tribut>ies _h cut rav9es or caons 9 ! basalts be=e ! gr\nd 0 buri$ "u ! floods ( pit*/one4 ,9 ! mo/ nor!rly spur ( ! ridge1 = example1 ! hill ( ,be9n ,tighe1 :i* repres5ts "o ( ^! tribut>ies1 %[s a consid]able diff]5ce betwe5 ! level ( ! bottom ( ! pit*/one on ! ea/ & we/ sides4 ,aga91 all along ! ridge ( ! ,scuir1 ! basalt-dykes are abruptly cut (f at ! d5ud$ surface on :i* ! pit*/one re/s4 ,?is feature is conspicu\sly display$ on ! great sea-wall at ! we/ end 7,fig4 #bgi74 ,! truncation ( ! dykes demon/rates t a consid]able mass ( mat]ial mu/ h be5 erod$ be=e ^! lava-fill$ fissures c\ld be laid b>e at ! surface4 ,& ! removal ( ?is mat]ial %[s t ! d5udation mu/ h be5 cont9u$ = a long p]iod ( "t4 ,! riv]-*annel ( ,eigg1 s9ce x 0 erod$ long aft] ! cessation ( ! outfl[s ( basalt 9 ! plateau ( ,small ,isles1 mu/ be mu* lat] 9 orig9 ?an ^? ( ,canna & ,s&ay :i*1 z we h se51 7 contemporane\s ) ! basalt-eruptions4 ,b ! riv] t excavat$ ! *annels & deposit$ ! gravels may h be5 ! same 9 bo? areas4 ,9 deal+ ) ?is subject1 ?\gh ! evid5ce is admitt$ly scanty1 we are n left :olly to conjecture4 ,a consid]ation ( ! g5]al topographical features ( ! wide region ( ! ,inn] ,hebrides1 f ! beg9n+ ( ! volcanic p]iod onw>d1 w conv9ce u t1 9 spite ( ! effects ( prolong$ basalt-eruptions1 ! p]si/5t fl[ ( ! dra9age ( ! ,we/]n ,highl&s mu/ h tak5 a we/]ly direction4 ,x 0 t[>ds ! we/ t ! l[ gr\nds lay4 ,?\gh ! long & broad valley :i* /ret*$ nor?w>ds f ,antrim1 betwe5 ! l9e ( ! ,out] ,hebrides & ! ,we/ ( ,scotl&1 0 gradually buri$ "u a dep? ( two or ?ree ?\s& feet ( lava1 ! volcanic pla9 t ov]spread x probably rema9$ ev5 to ! end l[] ?an ! m\nta9\s ,we/]n ,highl&s4 ,h5ce ! riv]s1 no matt] h[ con/antly !y may h _h _! b$s fill$ up & may h be5 driv5 into new *annels1 w\ld nev]!less always seek _! way we/w>ds into ! ,atlantic4 ,on ,canna & ,s&ay ! traces ( a riv] are pres]v$ :i* p\r$ its flood-wat]s across ! lava-fields 9 t "p ( ! volcanic region1 :ile /reams ( basalt 7 /ill f "t to "t issu+ f v5ts & fissures4 ,n m ?an f\rte5 miles to s\?-ea/ /&s ! ,scuir ( ,eigg1 ) its buri$ riv]-*annel & its /rik+ evid5ce t !re1 also1 a riv] fl[$ we/w>ds1 b at a f> lat] "t1 :5 ! basalt-eruptions _h ceas$ & ! volcanic pla9 _h be5 already deeply tr5*$ by erosion1 yet be=e ! subt]ranean fires 7 f9ally qu5*$1 z ! pit*/one ( ! ,scuir abundantly proves4 ,:5 "o reflects ^u ! enorm\s d5udation ( ?is region1 to :i* m special ref]5ce w be made 9 ! sequel1 "o is n surpris$ t _m connect+ l9ks %\ld h be5 effac$4 ,! a/oni%m5t r arises t s cont9u\s a /ory c /ill be deciph]$4 ,ev51 h[ev]1 _h ! orig9al record be5 left complete1 x w\ld h be5 exce$+ly difficult to trace ! successive mutations ( a riv]-*annel dur+ long ages ( volcanic eruptions4 ,su* a *annel w\ld h be5 conceal$ f view by ea* lava-/ream t p\r$ into x1 & w\ld n h be5 aga9 expos$ save by ! v process ( erosion t de/roys :ile x reveals4 ,:ile1 !re=e1 !re is n & c nev] be any positive pro( t 9 ! fluviatile records ( ,canna1 ,s&ay & ,eigg successive phases are regi/]$ 9 ! hi/ory ( "o s+le /ream1 ,i believe t ?is id5tity is highly probable4 ,x 0 a riv] :i* seems to h ris5 among ! m\nta9s ( ,we/]n ,inv]ness-%ire1 & x _h d\btless already tak5 its c\rse to ! sea be=e any volcanic eruptions began4 ,x cont9u$ to fl[ we/w>ds across ! lava-floor t gradually spread ov] ! pla9s4 ,its *annel 0 con/antly be+ fill$ up by fre% /reams ( basalt or deflect$ by ! uprise ( new c9d]-cones4 ,b1 f$ by ! ,atlantic ra9s1 x ma9ta9$ its seaw>d fl[ until ! g5]al subsid5ce :i* c>ri$ s mu* ( ! volcanic pla9 bel[ ! sea4 ,yet ! high] "p ( ?is anci5t wat]-c\rse is no d\bt unsubm]g$1 /ill trav]s+ ! s*i/s ( ! ,we/]n ,highl&s z x has done s9ce old] ,t]ti>y "t4 ,x may1 p]haps1 be recogniz$ 9 "o ( ! gl5s :i* c>ry seaw>d ! dra9age ( ! di/ricts ( ,mor>1 ,arisaig1 or ,moid>t4 ,illu/ration3 ,fig4 #bhj4--,view ( ! ,scuir ( ,eigg f ! ,s\?4 ,let u n[ turn to ! rem>kable lava :i* has seal$ up ! riv]-*annel ( ,eigg1 & ( :i* ! rema9+ fragm5t /&s up z ! great ridge ( ! ,scuir4 ,?is rock pres5ts *>act]s t /rongly di/+ui% x f ! surr\nd+ basalts4 ,x is n "o s+le uni=m mass1 b consi/s ( a numb] ( di/9ct v>ieties1 "s ( :i* are a volcanic glass1 :ile o!rs are a grey porphyry1 or devitrifi$ pit*/one4 ,^! are arrang$ 9 some:at irregul>1 b well-m>k$1 &1 9 a g5]al s5se1 horizontal %eets4 ,on ! great ea/]n t]m9al gable ( ! ,scuir ?is b$d$ /ructure is n cle>ly display$1 = ! cliff seems !re to be built up ( "o homog5e\s mass1 save a m>k$ly column> b& t runs obliquely up ! base ( ! precipice 7,fig4 #bgh74 ,if1 h[ev]1 ! ridge is look$ at f ! s\?1 ! truly b$d$ "* ( its mat]ials becomes a conspicu\s feature4 ,along ! cliffs on t side ! two v>ieties ( rock are /rongly di/+ui%$ by _! contra/+ col\r & mode ( wea!r+1 ! sombre-hu$ pit*/one /&+ up 9 a huge precipice /rip$ ) columns1 & b>r$ horizontally ) b&s ( ! pale-grey porphyry1 :i*1 f its great] pron5ess to decay1 seems sunk into ! face ( ! cliff4 ,at ! s\?-ea/ end ( ! ridge ! b$d+ is especially di/9ct4 ,we/ ( ! precipices1 to ! s\? ( ! ,lo* a' ,bhealai*1 ! d>k pit*/one :i* =ms ! ma9 mass is divid$ by two long p>allel int]calations ( grey rock1 & two o!r %ort l5ticul> seams ( ! same mat]ial 7see ,figs4 #bhj1 #bha74 ,x is cle> f ^! features1 :i* are n se5 by mo/ travell]s :o pass ,eigg 9 ! t\ri/-/eam] t ! ,scuir is 9 no s5se ( ! ^w a dyke4 ,b al?\gh ! ,scuir is ?us a b$d$ mass1 ! b$d+ is f> diff]5t f ! regul>ity & p>allelism ( t :i* obta9s among ! b$d$ basalt-rocks bel[4 ,ev5 :]e no int]v5+ porphyry occurs1 ! pit*/one c be recogniz$ z made up ( _m b$s1 ea* m>k$ by ! diff]5t angle at :i* its columns lie4 ,& :5 ! porphyry does occur & =ms s /rik+ a division 9 ! pit*/one1 its b$s die out rapidly1 appe>+ n[ on "o horizon1 n[ on ano!r1 along ! face ( ! cliffs1 & ?ick5+ & ?9n+ abruptly 9 %ort di/ances along ! l9e ( ! same b$4 ,p]haps ! be/ place = exam9+ ^! features is at ! ,bhealai*1 ! only gully practicable = asc5t or desc5t1 at ! s\?-ea/]n face ( ! ridge4 ,illu/ration3 ,fig4 #bha4--,view ( ! ,scuir ( ,eigg f ! ,s\?-we/ ( ! ,lo* a' ,bhealai*1 %[+ ! b$d$ "* ( ! mass4 ,by mu* ! l>g] "p ( ! mass ( ! ,scuir consi/s ( vitre\s mat]ial4 ,z a rule ?is rock is column>1 ! columns be+ mu* slimm] & %ort] ?an ^? ( ! basalt-rocks4 ,!y rise sometimes v]tically1 & (t5 obliquely1 or project ev5 horizontally f ! face ( ! cliff4 ,!y are seldom q /raight1 b h a wavy outl9e2 & :5 gr\p$ 9 knolls "h & !re along ! top ( ! ridge !y rem9d "o ( gigantic bun*es ( "s ( ! ,palozoic corals1 su* z ,li?o/rotion4 ,9 o!r cases !y slope out f a common c5tre1 & %[ an arrangem5t n v unlike t ( a ,highl& peat-/ack4 ,! pit*/one ( ! ,scuir diff]s consid]ably 9 petrographical "* f o!r pit*/ones ( ! isl& :i* occur 9 dykes & ve9s4 ,its base is ( a velvet-black col\r1 & is s mu* less vitre\s 9 aspect ?an ord9>y pit*/one z to h be5 describ$ by ,jameson & lat] writ]s z int]m$iate betwe5 pit*/one & basalt4#bed ,a *emical analysis ( ! rock by ,mr4 ,b>k] ,nor?1#bee gave ! foll[+ composition3-- ,silica #feha ,alum9a #adja ,f]ric oxide #ddc ,lime #bja ,magnesia #jhi ,soda #dae ,pota% #fjh ,loss 9 ignition #bgj ------ #ajjjh ,footnote #bed3 ,m9]alogy ( ! ,scotti% ,isles1 vol4 ii4 p4 #dg4 ,see also ,maccullo*1 ,we/]n ,isles1 vol4 i4 p4 #eba1 & ,hay ,cunn+ham1 ,mem4 ,w]n4 ,soc4 vol4 viii4 p4 #aee4 ,footnote #bee3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlvi4 7#ahij71 p4 #cgi4 ,! grey devitrifi$ b&s1 :i* occur z a subord9ate "p ( ! mass ( ! ,scuir ridge1 are usually some:at decompos$4 ,:]e a fre% fracture is obta9$1 ! mat]ial %[s a f9e-gra9$1 sometimes almo/ fl9ty1 grey felsitic base1 conta9+ cle> granules ( qu>tz1 & facets ( glassy felsp>4 ,9 "s places ! rock is /rongly porphyritic4 ,exam9$ "u ! microscope x pres5ts a m ?or\ghly devitrifi$ gr\ndmass1 ) ! m9ute/ depol>iz+ microlites1 l>ge porphyritic cry/als ( plagioclase & sanid9e1 gra9s ( augite1 & sometimes exce$+ly abundant p>ticles ( magnetite4#bef ,footnote #bef3 ,! microscopic /ructure ( ! id5tical pit*/one ( ,hysgeir is giv5 on p4 #bdg4 ,illu/ration3 ,fig4 #bhb4--,section at ! base ( ! ,scuir ( ,eigg 7ea/ end74 ,al?\gh ! l9e ( sep>ation betwe5 ! grey dull felsitic %eets & ! m ord9>y glassy pit*/one is usually well def9$1 ! two rocks may be obs]v$ to %ade into ea* o!r 9 su* a mann] z to %[ t ! li?oid mat]ial is only a devitrifi$ & some:at decompos$ condition ( ! glassy rock4 ,?is connection is p>ticul>ly to be obs]v$ "u ! precipice at ! ea/ end ( ! ,scuir4 ,at t locality ! pit*/one is und]la9 by a v h>d fl9ty b&1 v>y+ 9 col\r f :ite ?r\gh v>i\s %ades ( fle%-col\r & br[n into black1 conta9+ a little free qu>tz & cry/als ( glassy felsp>4 ,:]e x becomes black x passes into a rock l t ( ! ma9 mass ( ! ,scuir4 ,su* vitre\s p>ts ( ! b$ lie z k]nels 9 ! mid/ ( ! m li?oid & decompos$ rock4 ,! l[] six feet ( ! porphyry are :ite & /ill m decompos$4 ,! relations ( ?is mass are repres5t$ 9 ,fig4 #bhb1 :]e ! basalt-rocks ( ! plateau 7a7 are %[n to be cut ?r\gh by basalt dykes 7b b71 & ov]la9 by ! porphyry 7c7 & ! pit*/one 7d74 ,9 ! porphyry are %[n sev]al pit*/one k]nels 7p1 p74 ,x is des]v+ ( rem>k also t 9 diff]5t p>ts ( ! ,scuir1 p>ticul>ly along ! nor? side1 ! bottom ( ! pit*/one b$s passes into a dull grey e>?y li?oid sub/ance1 l t n[ "u description4 ,! b$d$ "* ( ! rock ( ! ,scuir & ! well-m>k$ li?ological di/9ction betwe5 its sev]al compon5t %eets %[ ! lava to h be5 ! product ( a numb] ( sep>ate outfl[s t f\nd _! way "o aft] ano!r into ! riv]-valley1 :i* 0 ! l[e/ gr\nd 9 ! vic9ity ( ! active v5t4 ,!re c be little d\bt1 ,i ?9k1 t ! lava fl[$ d[n ! valley4 ,its successive /reams are /ill incl9$ f ea/ to we/4 ,! v5t ( eruption1 !re=e1 ought to be look$ = t[>ds ! ea/4 ,n[h]e )9 ! ,t]ti>y volcanic region is !re any boss ( pit*/one or any mass ! %ape or size ( :i* is sugge/ive ( ?is v5t4 ,9 ! isl& ( ,eigg no boss ( any k9d exi/s1 save ^? ( granophyric porphyry to be aft]w>ds ref]r$ to4 ,b none ( ^! af=ds any satisfactory l9ks ( connection ) ! rock ( ! ,scuir4 ,m probably ! v5t lay some:]e to ! ea/ on gr\nd n[ ov]fl[$ by ! sea4 ,! pit*/one ve9s ( ,eigg may repres5t "s ( ! subt]ranean extrusions f ! same volcanic pipe1 & if s1 its site c\ld n be f> (f4 ,! rock ( ! ,scuir ( ,eigg has a special importance 9 ! hi/ory ( ! volcanic plateaux4 ,x is1 s f> z we "k1 ! late/ ( all ! sup]ficial lavas ( ,brita94#beg ,f ! basalts on :i* x re/s x 0 sep>at$ by an enorm\s int]val ( "t1 dur+ :i* ^! old] lavas 7 trav]s$ by dykes & 7 worn d[n into valleys4 ,its pres5ce %[s t long aft] ! basalts ( ,small ,isles _h ceas$ to be erupt$1 a new outbreak ( volcanic activity took place 9 ?is di/rict1 :5 lavas ( a m acid composition fl[$ out at ! surface4 ,:e!r ?is outbur/ 0 syn*ron\s ) ! appe>ance ( ! great granophyric protrusions ( ! ,inn] ,hebrides1 or ) ! /ill lat] extravasation ( pit*/one dykes1 c only be surmis$4 ,footnote #beg3 ,! rocks ( ,be9n ,hiant 9 ,ardnamur*an h be5 claim$ by ,pr(essor ,judd z sup]ficial lavas4 ,= reasons to be aft]w>ds giv5 7p4 #cah7 ,i reg>d !m z intrusive %eets4 ,pr(essor ,cole believes ! rhyolites & pit*/ones ( ,t>dree to be probably evid5ce ( a volcano lat] ?an ! basalts ( ,antrim4 ,z ,i h n be5 able to detect any actual pro(s ( sup]ficial outfl[ !re1 ,i relegate ! description ( ! rocks to a future *apt]1 9 :i* ! acid protrusions w be discuss$ 7p4 #dbf74 ,:5 "o scans ! great precipice on ! we/ side ( ,eigg1 ) its transv]se section ( ! pit*/one-lava1 buri$ riv]-b$ & basalt-plateau und]nea?1 !re seems no *ance ( any fur!r we/w>d trace ( ! pit*/one be+ ev] f\nd4 ,! truncat$ end ( ! ,scuir looks f ! top ( ! cliff out to sea1 & ! progress ( d5udation might h be5 suppos$ to h effectually de/roy$ all evid5ce ( ! cont9uation ( ! rock 9 a we/]ly direction4 ,"s ye>s ago1 h[ev]1 my fri5d ,pr(4 ,h$dle1 :ile cruis+ among ! ,inn] ,hebrides1 l&$ ^u ! little un9habit$ islet ( ,hysgeir1 :i*1 "s eighte5 miles to ! we/w>d ( ,eigg1 rises out ( ! op5 sea4 ,he at once recogniz$ ! id5tity ( ! rock compos+ ?is islet ) t ( ! ,scuir1 & 9 ! ye> #ahib publi%$ a brief acc\nt ( ?is int]e/+ discov]y4#beh ,footnote #beh3 ,app5dix ,c to ,a ,v]tebrate ,fauna ( ,argyle & ! ,inn] ,hebrides1 by ,messrs4 ,j4 ,a4 ,h>vie-,br[n & ,?omas ,e4 ,buckley1 p4 #bdh4 ,i h myself be5 able to l& on ,hysgeir 9 two successive summ]s1 & c entirely confirm ,pr(4 ,h$dle's id5tification4 ,! islet /&s on ! ea/]n edge ( ! subm>9e ridge :i*1 runn+ 9 a nor?-ea/]ly direction1 culm9ates 9 ! isl& ( ,canna4 ,hysgeir is a m]e reef or sk]ry1 ( :i* ! top rises only #ch feet above ! ,ordnance datum-level4 ,its surface is "o ( b>e rock1 save :]e a %ort b luxuriant gr[? ( grasses has f\nd root on ! high] p>ts ( two or ?ree ( its ridges1 & on ! old /orm-bea* ( %+le :i* rema9s on ! summit4 ,! rock undulates 9 long l[ swells1 t run 9 a g5]al direction #bj to #de we/ ( nor?1 & are sep>at$ by n>r[ *annels or holl[s4 ,! place is a fav\rite haunt ( gulls1 t]ns1 eid]-ducks & grey seals1 & is us$ by ! proprietor ( ,canna = ! occasional pa/urage ( %eep or cattle4 ,s num]\s are ! sea-f[l dur+ ! bre$+-season t ! geologi/1 int5t ^u 8 own pursuits1 may (t5 tread on _! ne/s unaw>es1 :ile he is ! c5tre ( a re/less circle ( :ite w+s & anxi\s cries4 ,! pit*/one ( ,hysgeir1 l t ( ,eigg1 is column>1 ! columns be+ irregul>ly polygonal & v>y+ f ?ree to t5 in*es 9 diamet]4 ,!y are pack$ s close toge!r t ! domes ( rock on :i* _! ends appe> look l r\nd$ masses ( honeycomb4 ,!y may "h & !re be obs]v$ to be arrang$ radially ) _! ends at "r angles to ! curv$ ext]ior ( ! ridges1 z if ?is ext]nal surface repres5t$ ! orig9al =m ( ! cool$ pit*/one1 & 7 n due to m]e d5udation4 ,!re c be no d\bt1 h[ev]1 t ! isl& has be5 well ice-worn4 ,at ! nor?-we/ promontory a beautiful example ( fan-%ap$ gr\p+ ( columns may be obs]v$ on a face ( rock :i* desc5ds v]tically into ! sea4 ,"h1 too1 is almo/ ! only section on :i* ! sides ( ! columns may be exam9$1 =1 z a rule1 x is m]ely _! ends on ! r\nd$ domes :i* are to be obs]v$1 & :i* ev]y:]e slip "u ! waves4 ,! columns 9 a cliff f #ae to #bj feet high %[ ! slightly wavy1 />*-l arrangem5t s (t5 to be met ) among ! plateau-basalts4 ,! rock pres5ts a tol]ably uni=m texture ?r\gh\t1 ?\gh 9 "s p>ts x is black]1 m res9\s1 & less *>g$ ) porphyritic enclosures ?an 9 ! g5]al body ( ! rock4 ,l>ge fre% felsp>s are g5]ally scatt]$ ?r\gh x4 ,to ! nak$ eye x reproduces e feature ( ! pit*/one ( ! ,scuir ( ,eigg4 ,a microscopic exam9ation completes our recognition ( ! id5tity ( ^! two rocks4 ,mr4 ,h>k] has exam9$ a ?9 slice prep>$ f ! ,hysgeir pit*/one1 & rem>ks reg>d+ x t ! l>ge felsp>s are n ! only porphyritic elem5t4 ,! microscope %[s ! pres5ce also ( small] imp]fect cry/als ( augite1 v fa9t gre5 9 ! slice1 & small gra9s ( magnetite4 ,! felsp>s h be5 deeply corrod$ by ! envelop+ magma1 & irregul> includ$ pat*es ( ! gr\ndmass occupy ne>ly half ! bulk ( "s ( ! cry/als4 ,?is latt] feature is se5 especially 9 "s ( ! l>g] cry/als1 :i* seem to be sanid9e4 ,!y are1 = ! mo/ "p1 app>5tly simple cry/als1 b 9 places !re is a sc>cely def9$ lamell> tw9n+1 or1 aga91 small pat*es n ext+ui%+ ) ! re/2 s t we are probably deal+ ) "s p]?itic int]gr[? on a m9ute scale4#bei ,footnote #bei3 ,comp4 ,pr(4 ,judd's rem>ks on ! ,scuir ( ,eigg rock1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlvi4 7#ahij71 p4 #chj4 ,r small] felsp>-cry/als are r\nd$ by corrosion1 b lack ! inclusions ( gr\ndmass2 ^! h albite-& sometimes p]icl9e-lamellation1 & may be ref]r$ to oligoclase-&es9e4 ,! gr\ndmass ( ! rock is a br[n glass ) p]litic cracks1 enclos+ v num]\s microlites ( felsp> ab\t #jja in* 9 l5g? #ffai4 ,! rock is probably to be reg>d$ z a dacite r ?an a rhyolite1 & ?us agrees ) ,mr4 ,b>k] ,nor?'s analysis ( ! ,eigg pit*/one4#bfj ,footnote #bfj3 ,op4 cit4 p4 #cgi4 ,!re is no trace ( any conglom]ate 9 situ l t "u ! ,scuir ( ,eigg1 nor ( any o!r rock1 aque\s or igne\s4 ,z ! pit*/one ev]y:]e slips "u ! sea1 its geological relations are entirely conceal$4 ,! great v>iety ( mat]ials met ) 9 ! =m ( b\ld]s on ! isl& is a te/imony to ! transport ( erratics f ! neighb\r+ isl&s & ! ma9l& dur+ ! ,glacial ,p]iod4 ,! mo/ abundant rock 9 ^! b\ld]s is ,torridon ,s&/one1 d]iv$ no d\bt f ! hills ( ,rum1 b !re occur also v>i\s k9ds ( s*i/1 gneisses1 qu>tzites1 granites1 porphyries1 probably f ! we/ ( ,inv]ness-%ire1 z well z pieces ( :ite s&/one1 probably ,jurassic1 :i* may h come f ,eigg4 ,t ! pit*/one ( ,hysgeir is a cont9uation ( t ( ! ,scuir may be reg>d$ z highly probable4 ,if n a cont9uation1 x mu/ be ano!r /ream ( ! same k9d1 & d\btless ( ! same date4 ,if x be reg>d$ z probably a we/w>d prolongation ( ! ,eigg rock1 & if x be ab\t z ?ick z t mass at ! we/ end ( ! ,scuir1 !n its bottom lies #bjj or #cjj feet "u ! waves4 ,! riv]-*annel occupi$ by ! ,eigg pit*/one und\bt$ly slop$ f ea/ to we/4 ,! position ( ,hysgeir1 #ah miles fur!r we/1 may indicate a fur!r fall 9 ! same direction at ! rate ( p]haps z mu* z #ce feet 9 ! mile4#bfa ,un=tunately1 h[ev]1 z no trace ( ! riv]-b$ c n[ be se5 on ?is isl&1 any /atem5t 9 reg>d to x mu/ re/ on m]e conjecture4 ,footnote #bfa3 ,rep4 ,brit4 ,assoc4 #ahid1 p4 #fec4 ,al?\gh ! "q ( ! d5udation ( ! basalt-plateaux s9ce ! close ( ! volcanic p]iod w be ! subject ( a special *apt] 9 a lat] "p ( ?is volume1 ,i _c "h refra9 f call+ att5tion to ! pit*/one ( ,eigg & ,hysgeir z "o ( ! mo/ impressive monum5ts ( d5udation to be f\nd )9 ! ,briti% ,isles4 ,?\gh n[ s prom95t an object 9 ! ,we/ ,highl&s1 ?is rock once occupi$ ! bottom ( a valley worn out ( ! basaltic tablel&4 ,prolong$ & /up5d\s d5udation has de/roy$ ! connection ) its s\rce1 has cut d[n its ends into beetl+ precipices1 has r$uc$ ! =m] surr\nd+ hills into g5tle slopes & undulat+ l[l&1 & has turn$ ! bottom ( ! anci5t valley into a long1 n>r[ & high cre/4 ,moreov]1 we see t ! erosion has n be5 uni=m4 ,! great wall ( ! ,scuir does n /& fairly on ! cre/ ( ! basalt-plateau b on ! s\? side ( x1 s t ! s\!rn half ( ! old valley1 ) all its surr\nd+ hills1 has be5 entirely cut away4 ,t subsid5ce has also come into play 9 ! de/ruction ( ev5 ! y\nge/ p>ts ( ! volcanic plateaux w be m fully discuss$ 9 a lat] *apt]4 ,i ne$ only rem>k "h t ! subm]g5ce ( ,hysgeir probably po9ts to ext5sive depression ( ! l&-surface on :i* ! lavas 7 p\r$ out4 ,,*apt] ,,xxxix ,,! ,,basalt-,,plateaux ,,( ,,skye ,,& ,,( ,,! ,,f>oe ,,isles iv4 ,,! ,,skye ,,plateau ,?is l>ge/ & geologically mo/ important ( all ! ,scotti% plateaux comprises ! isl& ( ,skye1 at lea/ z f> s\? z ,lo* ,ei%ort1 & ! s\!rn half ( ,raasay1 b is %[n by its sills to /ret* z f> z ! ,%iant ,isles on ! nor?1 & ! ,po9t ( ,sleat on ! s\? 7see ,map ,,vi474 ,x may be reckon$ to embrace an area ( n less ?an #hjj squ>e miles4 ,! evid5ce t its limits1 l ^? ( ! o!r plateaux1 are n[ greatly less ?an !y orig9ally 71 is abundant & impressive4 ,! truncat$ edges ( its basalts1 ris+ "h & !re = a ?\s& feet z a great sea-wall above ! break]s at _! base1 & pres5t+ ev]y:]e _! succession ( level or g5tly incl9$ b>s1 are among ! mo/ impressive monum5ts ( d5udation 9 ?is c\ntry4 ,b /ill m /rik+ to ! geologi/ is ! pro(1 furni%$ beyond ! m>g9s ( ! plateau1 t ! ,jurassic & o!r old] rocks !re visible 7 orig9ally buri$ deep "u ! basalt-%eets1 :i* h ?us be5 entirely /ripp$ (f t "p ( ! c\ntry4 ,?r\gh\t mo/ ( ! di/rict1 :]ev] ! base ( ! basalts c be se51 x is f\nd to re/ ^u "s memb] ( ! ,jurassic s]ies1 b ) a complete uncon=mability4 ,! und]ly+ s$im5t>y /rata _h be5 dislocat$ & ext5sively d5ud$ be=e ! volcanic p]iod began4 ,on ! s\!rn m>g91 h[ev]1 ! r$ 7,torridon7 s&/ones em]ge f "u ! basalts ( ,lo* ,scavaig1 & ext5d+ into ! isl& ( ,soay are prolong$ "u ! sea into ,rum4 ,?is ridge probably repres5ts ! range ( ! anci5t high gr\nd ( ! latt] isl& already ref]r$ to4 ,n[h]e are ! di/9ctive topographical features & geological /ructure ( ! basalt-plateaux bett] display$ ?an 9 ! nor!rn half ( ! isl& ( ,skye4 ,! gre5 t]rac$ slopes1 ) _! p>allel b&s ( br[n rock =m$ by ! outcrop ( ! ne>ly flat basalt-b$s1 rise f ! bottoms ( ! valleys into flat-topp$ ridges & truncat$ cones 7,fig4 #bhc74 ,! hills ev]y:]e pres5t a curi\sly tabul> =m t be>s witness to ! horizontal %eets ( rock ( :i* !y are compos$4#bfb ,& along ! sea-precipices1 ea* excessive %eet ( basalt c be c\nt$ f base to summit1 & foll[$ f promontory to promontory 7,figs4 #bhd1 #bhf74 ,9 ! di/rict ( ,trott]ni%1 ! basalt hills rea* a height ( #bcfj feet4 ,fur!r we/1 ! s+ul> flat-topp$ em95ces1 call$ ,macleod's ,tables 7,fig4 #bhc7 asc5d to #afjj feet4 ,footnote #bfb3 ,^! features are m fully describ$ 9 my ,sc5]y ( ,scotl&1 #bnd edit 7#ahhg71 pp4 #gd1 #ade1 #baf4 ,illu/ration3 ,fig4 #bhc4--,t]rac$ ,hills ( ,basalt ,plateau 7,macleod's ,tables71 ,skye4 ,along ! we/]n side ( ,skye1 ! basalts desc5d b5ea? ! level ( ! ,atlantic1 save at ,ei/ 9 ,duir9i%1 :]e ! ,second>y /rata1 ) _! belt ( intrusive sills1 rise f und]nea? !m1 & at ! ,s\nd ( ,soa1 :]e !y re/ on ! ,torridon ,s&/one4 ,along ! ea/]n side1 _! base runs on ! top ( ! great ,jurassic esc>pm5t1 ^: :ite & yell[ s&/ones rise !re1 & on ! ea/ side ( ,raasay1 into long l9es ( pale cliffs4 ,to ! s\?-ea/1 ! regul>ity ( ! volcanic plateau is effac$1 z 9 ,mull & ,ardnamur*an1 by ! protrusion ( ext5sive masses ( eruptive rocks con/itut+ ! ,cuill9 & ,r$ ,hills1 ea/ ( :i* ! basalts h be5 almo/ entirely remov$ by d5udation1 s z to expose ! old] rocks :i* !y once cov]$1 & ?r\gh :i* ! y\ng] eruptive bosses made _! way4 ,?is is und\bt$ly ! mo/ in/ructive di/rict = ! /udy ( t late phase 9 ! volcanic hi/ory ( ,brita9 compris$ 9 ! eruptive bosses ( basic & acid rocks4 ,! magnific5t plateau ( ?is isl& has be5 s pr(\ndly cut d[n into gl5s & arms ( ! sea1 & its compon5t lay]s are expos$ along s _m leagues ( precipice1 t its /ructure is p]haps m completely laid op5 ?an t ( any ( ! o!r ,t]ti>y volcanic areas 9 ,brita94 ,x is built up ( a succession ( basalts & dol]ites ( ! usual types1 :i* /ill rea* a ?ickness ( m ?an #bjjj feet1 ?\gh 9 ?is in/ance1 also1 d5udation has left only a portion ( !m1 )\t any evid5ce by :i* to reckon :at _! total orig9al dep? may h be54 ,9 rambl+ ov] ,skye1 ! geologi/ is m ?an ev] /ruck ) ! rem>kable sc>city & insignificance ( ! int]/ratifications ( tuff or ( any o!r k9d ( s$im5t>y deposit betwe5 ! successive lava-%eets4 ,"o ( ! ?icke/ accumulations ( volcanic tuff & conglom]ate has already be5 ref]r$ to z occurr+ on ! s\? side ( ,portree ,h>b\r1 :]e x atta9s a dep? ( ab\t #bjj feet4 ,z x is 9 imm$iate connection ) its p>5t v5t1 x w be m fully allud$ to 9 ,*apt] xli4 ,"h1 z is s g5]ally obs]vable among ! basalt-plateaux1 traces ( vegetation are pl5tiful among ! /ratifi$ int]calations1 ev5 =m+ ?9 seams ( lignite & coal1 "o ( :i* 0 =m]ly work$4 ,t volcanic eruptions1 ?\gh possibly ( a feebl] k9d1 cont9u$ dur+ ! int]val betwe5 ! basalt-outfl[s at ?is locality1 is %[n by ! ?ick accumulation ( tuff & by ! occurr5ce ( abundant lapilli ( f9e basic pumice among ! %ales1 ev5 to a di/ance ( sev]al miles f ! v5t4 ,illu/ration3 ,fig4 #bhd4--,macleod's ,maid5s & "p ( ,basalt ,cliffs ( ,skye4 ,ano!r conspicu\s int]calation ( s$im5t>y mat]ials 9 ! ,skye plateau occurs on ! ,talisk] cliffs at ! m\? ( ,lo* ,bracadale1 :]e1 on ! face ( ! great precipice ( ,rudha nan ,cla*1 "s conspicu\s b&s ( lilac & r$ are int]sp]s$ among ! basalts4 ,^! b&s 7 notic$ by ,maccullo*1 :o describ$ !m z v>ieties ( iron-clay4#bfc ,i h n _h an opportunity ( exam9+ !m except f ! sea at a little di/ance4 ,b !y sugge/ a simil>ity to "s ( ! v>iegat$ clays betwe5 ! upp] & l[] basalt s]ies ( ,antrim4 ,footnote #bfc3 ,we/]n ,isl&s1 vol4 i4 p4 #cgf4 ,?\gh good coal is n well develop$ 9 ! ,t]ti>y volcanic plateaux ( ! ,briti% ,isles1 x has already be5 po9t$ out t coaly lay]s are abundant1 & t z ! vegetable matt] may confid5tly be assum$ always to indicate t]re/rial vegetation1 ! pres5ce ( ! c>bonace\s b&s may be reg>d$ z good evid5ce ( "s lapse ( "t betwe5 ! eruption ( ! basalts :i* !y sep>ate4 ,i h also call$ att5tion to ! fact t ! vegetable mat]ial is m especially obs]vable 9 ! highe/ p>ts ( a gr\p ( int]calat$ s$im5ts betwe5 two %eets ( basalt4 ,?is relation1 s /rik+ly exhibit$ 9 ! isle ( ,canna1 z already obs]v$1 is also to be rem>k$ 9 ! ,skye plateau4 ,i may "h cite an int]e/+ example :i* occurs at ! base ( ! l(ty sea-cliff ( ,an ,ceannai*1 to ! s\? ( ,dunvegan ,head1 on ! we/ coa/ ( ,skye 7,fig4 #bhe74 ,at ! base ( ! precipice1 l$ges ( a highly cellul> basalt 7a7 %[ a s+ul>ly scoriace\s & amygdaloidal /ructure1 ) abundant & beautiful zeolites1 ! holl[s ( ! upp] surface ( ! %eet be+ fill$ 9 ) d>k br[n c>bonace\s %ale1 =m+ a lay] f "o to f\rte5 in*es ?ick1 m>k$ by coaly /reaks & l5ticles 7b74 ,a b& ( gre5 & yell[ s&/one 7c7 next sup]v5es1 :i*1 f its pale col\r1 attracts att5tion f a di/ance1 & l$ me1 :ile ya*t+ along ! coa/1 to l& at ! locality 9 ! hope t x might prove to be a plant-be>+ lime/one4 ,?is s&y /ratum is only "s ?ree or f\r in*es ?ick at ! nor? end ( ! section1 b increases rapidly s\?w>d to a ?ickness ( z _m feet or m1 :51 ow+ to ! cessation ( ! und]ly+ %ale1 x comes to lie directly on ! amygdaloid & to enclose slaggy portions ( t rock4 ,imm$iately above ! s&/one two or ?ree feet ( fissile %ale1 black ) plant-rema9s 7d71 include br[n lay]s t yield to ! knife l "s oil-%ales4 ,! next /ratum is a seam ( coal 7e7 ab\t a foot ?ick1 ( rem>kable purity4 ,x is glossy1 h>d1 & cubical1 includ+ lay]s t break l jet4 ,x has be5 succe$$ by a deposit ( gre5 s& 7f71 b :ile ?is mat]ial 0 9 c\rse ( deposition ano!r outp\r+ ( lava 7g7 took place1 :]eby ! t]re/rial pool or holl[ ( ! lava-field1 9 :i* ! gr\p ( s$im5t>y mat]ials accumulat$1 0 fill$ up & buri$4 ,?is lava is ab\t #bj feet ?ick1 & consi/s ( a co>sely-cry/all9e1 jo9t$ dol]ite ) highly amygdaloidal upp] & "u surface4 ,its slaggy bottom has caught up or pu%$ aside ! lay] ( gre5 s&1 s z to lie directly on ! coal1 & has !re be5 conv]t$ into ! e>?y modification s famili> "u ! "n ( :ite trap among our coal-fields4 ,x is int]e/+ to f9d t ?is k9d ( alt]ation1 :]e molt5 rock comes 9 contact ) c>bonace\s mat]ials1 is n conf9$ to subt]ranean sills1 b may %[ itself 9 lavas t h fl[$ ov] a t]re/rial surface4 ,illu/ration3 ,fig4 #bhe4--;,int]calat$ gr\p ( /rata betwe5 ,basalts1 ,an ,ceannai*1 we/]n side ( ,skye4 ,f ! frequ5t int]calation ( su* local deposits ( s$im5t>y mat]ial betwe5 ! basalts1 we may reasonably inf] t dur+ old] ,t]ti>y "t ! ra9fall 9 ,nor?-,we/]n ,europe 0 copi\s en\gh to supply _m little lakes & /reams ( wat]4 ,z ! surface ( ! lava-fields decay$ into soil1 vegetation spread ov] x1 s t1 p]haps = long int]vals1 "s tracts rema9$ gre5 & =e/-clad4 ,b volcanic action /ill cont9u$ to %[ itself1 n[ f "o v5t1 n[ f ano!r4 ,^! wood$ tracts 7 buri$ "u ov]fl[s ( lava1 &1 ! wat]-c\rses be+ fill$ up1 _! /reams 7 driv5 into new *annels1 & o!r pools & lakes 7 =m$4 ,illu/ration3 ,fig4 #bhf4--;,esc>pm5t ( ,plateau-basalts1 ,cliffs ( ,talisk]1 ,skye4 ,9 no "p ( ! ,t]ti>y volcanic area ( ,brita9 c ! *>act]s ( ! lavas & ! /ructure ( ! plateaux be bett] se5 ?an along ! we/ side ( ,skye1 nor? ( ,lo* ,bracadale4 ,! precipices rise %e] out ( ! sea1 to heights ( sometimes #ajjj feet1 & f base to summit e individual b$ may be c\nt$4 ,"s p>ticul>s h already be5 giv5 7p4 #aib7 reg>d+ ! av]age ?ickness ( ! basalt-%eets on ?is coa/-l9e4 ,! g5]al aspect ( ^! cliffs & ! arrangem5t ( _! compon5t lavas is %[n 9 ,fig4 #bhf4 ,z a fur!r detail$ illu/ration ( ! g5]al succession ( ! basalts 9 ! ,skye plateau1 ,i give a diagrammatic view ( ! l>ge/ ( ,macleod's ,maid5s--! ?ree weird sea-/alks t rise s gr&ly 9 front ( ! /orm-swept precipice at ! m\? ( ,lo* ,bracadale4 ,! height ( ! /ack mu/ be at lea/ #aej feet 7,figs4 #bhd & #bhg74 ,ab\t t5 di/9ct %eets ( igne\s rock c be c\nt$ 9 x1 :i* gives an av]age ?ickness ( #ae feet = ! individual b$s4 ,x w be obs]v$ t !re is a k9d ( alt]nation betwe5 ! compact1 prismatic basalts & ! m e>?y amygdaloids1 b t ! =m] are g5]ally ?icke/4#bfd ,footnote #bfd3 ,a /rik+ & illu/rative contra/ betwe5 ! relative ?ickness ( ! b$s ( ! two k9ds ( rock is suppli$ by ! f9e sections ( ?is di/rict4 ,! amygdaloids range f p]haps #f or #h to #be or #cj feet2 b ! prismatic basalts1 :ile nev] s ?9 z ! o!rs1 sometimes enorm\sly exce$ !m 9 bulk4 ,9 ! isl& ( ,wiay1 = example1 a b$ ( compact black basalt1 ) ! confus$ />*-l gr\p+ ( columns1 rea*es a ?ickness ( no less ?an #agj feet4 ,its bottom re/s ^u a r$ p>t+ on ! top ( a dull gre5i% e>?y amygdaloid4 ,x is possible1 h[ev]1 t "s ( ^! column> %eets ( basalt are really sills4 ,illu/ration3 ,fig4 #bhg4--,section ( ! l>ge/ ( ,macleod's ,maid5s4 ,^! features1 :i* are repeat$ on cliff aft] cliff1 may be consid]$ typical = all ! plateaux4 ,ano!r *>act]i/ic po9t1 well display$ "h1 is ! int]v5+ r$ p>t+ betwe5 ! successive b$s4 ,if ! occurr5ce & ?ickness ( ?is lay] c\ld be assum$ z an indication ( ! relative lapse ( "t betwe5 ! diff]5t fl[s ( lava1 x w\ld furni% u ) a rude k9d ( *ronomet] = e/imat+ ! proportionate duration ( ! int]vals betwe5 ! eruptions4 ,x is to be notic$ on ! top bo? ( ! compact prismatic & ( ! e>?y amygdaloidal %eets2 b x is m frequ5t & g5]ally ?ick] on ! latt] ?an on ! =m]1 :i* may only mean t ! surfaces ( ! cellul> lavas 7 m prone to subrial decay ?an ^? ( ! compact v>ieties4 ,nev]!less1 ,i am dispos$ to atta* "s value to x1 z an index ( "t4 ,9 ! pres5t in/ance1 = example1 x seems to me probable t ! lavas 9 ! l[] half ( ,macleod's ,maid51 :]e ! r$ lay]s are v prom95t1 7 p\r$ out at long] int]vals ?an ^? t =m ! upp] half4 ,! rem>kable b&$ arrangem5t ( ! vesicles 9 "o ( ! cellul> lavas ( ?is sea-/ack has be5 already ref]r$ to 7p4 #aia74 ,ano!r *>act]i/ic plateau-feature is admirably display$ 9 ,skye--! flatness ( ! basalts & ! cont9uity ( _! level t]races 7?\gh n ( individual %eets7 f cliff to cliff & hillside to hillside4 ,?is feature may be foll[$ ) almo/ tiresome monotony ov] ! :ole ( ! isl&1 nor? ( a l9e drawn f ,lo* ,brittle to ,lo* ,sliga*an4 ,?r\gh\t t wide region1 ! regul>ity ( ! basalt-plateau is unbrok51 except by m9or protrusions ( eruptive rock1 :i*1 z f> z ,i h notic$1 d n s]i\sly affect ! topography4 ,b s\? ( ! l9e j indicat$1 ! plateau und]goes ! same rem>kable *ange z 9 ,rum1 ,ardnamur*an & ,mull4 ,portions ( x :i* h surviv$ indicate ) suffici5t cle>ness t x once spread s\?w>ds & ea/w>ds ov] ! m\nta9\s di/rict1 & ev5 f>!r s\? into ! l[ p>ts ( ! isl&4 ,its removal f t tract has be5 ( ! utmo/ value to geological rese>*1 = "s ( ! subt]ranean aspects ( volcanism h !reby be5 reveal$1 :i* w\ld o!rwise h rema9$ buri$ "u ! ?ick cov] ( basalt4 ,d5udation has likewise cut deeply into ! eruptive bosses1 & has c>v$ out ( !m ! gr\ps ( ! ,r$ ,hills & ! ,cuill9s1 to ^: picturesque =ms ,skye owes s mu* ( its *>m4 ,9 ?is1 z 9 ea* ( ! o!r plateaux1 !re is no trace ( any ?ick5+ ( ! basalts t[>ds a suppos$ c5tral v5t ( eruption4 ,! ne>ly level %eets may be foll[$ up to ! v edge ( ! great m\nta9\s tract ( eruptive rocks1 reta9+ all ! way _! usual *>act]s2 !y d n become ?ick] !re ei!r collectively or individually1 nor are !y m abundantly int]/ratifi$ ) tuffs or volcanic conglom]ates4 ,on ! contr>y1 _! v base is expos$ ar\nd ! m\nta9 gr\nd1 & ! ?icke/ int]/ratifications ( fragm5t>y mat]ials are f\nd at a di/ance f t area4 ,s f> z reg>ds ! /ructure ( ! rema9+ "p ( ! plateau1 ! eruption ( ! gabbros & granitoid rocks might app>5tly h tak5 place z well any:]e fur!r nor?4 v4 ,,! ,,f>oe ,,isl&s#bfe ,footnote #bfe3 ,= ref]5ces to ! rec5t geological lit]ature connect$ ) ^! isl&s see ! footnote ante1 p4 #aia4 ,?\gh ^! isl&s lie beyond ! limits ( ! region embrac$ by ! pres5t "w1 ,i wi% to cite !m = ! s+ul> confirmation & ext5sion !y af=d to obs]vations made among ,briti% ,t]ti>y volcanic rocks4 ,ov] a unit$ ext5t ( coa/-cliffs :i* may be r\ghly e/imat$ at ab\t #ejj ,engli% miles1 ! ne>ly level %eets ( basalts1 ) _! occasional tuffs1 conglom]ates1 leaf-b$s & coals1 c be foll[$ ) s+ul> cle>ness4 ,al?\gh ! ,f>oe ,isl&s h be5 s frequ5tly visit$ & s (t5 describ$ t _! g5]al /ructure is suffici5tly well kn[n1 !y pres5t 9 _! details su* a mass ( new mat]ial = ! illu/ration ( volcanic action t !y des]ve a f> m m9ute & pati5t survey ?an !y h yet receiv$4 ,!y _c be adequately mapp$ & und]/ood by ! travell] :o m]ely sails r\nd !m4 ,!y mu/ be labori\sly explor$1 isl& by isl& & cliff by cliff4 ,:ile ,i _c pret5d to m ?an a m]e g5]al acqua9tance ) _! /ructure1 ,i h le>nt by exp]i5ce t "o may sail ne> _! precipices & yet miss "s ess5tial features ( _! volcanic /ructure4 ,9 ! summ] ( ! ye> #ahid ,i pass$ close to ! noble range ( precipices on ! we/ side ( ,/rom1 at ! m\? ( ! ,vaagfjord1 & sket*$ ! sill :i* =ms s /rik+ a "p ( ! geology ( t di/rict 7,figs4 #cab1 #cbh & #cbi74 ,b ,i fail$ to obs]ve a mu* m rem>kable & int]e/+ feature at ! base ( ! same sea-cliffs4 ,! foll[+ summ]1 probably "u bett] conditions ( light1 ,i 0 =tunate en\gh to detect ) my field-glass1 f ! deck ( ! ya*t1 :at look$ l a mass ( agglom]ate1 & f\nd on clos] exam9ation ! int]e/+ gr\p ( volcanic v5ts describ$ 9 ,*apt] xli4 ,! magnific5t precipices ( ,f>oe1 :i* 9 ,myl+ ,head rea* a height ( #bbfj feet1 pres5t a s]ies ( natural sections altoge!r )\t a rival 9 ! re/ ( ,europe4 ,!y are less conceal$ ) v]dure ?an ^? ( ,mull & ,skye1 & !re=e display _! geological details ) ev5 great] cle>ness ?an c be f\nd ei!r 9 ,scotl& or 9 ,irel&4 ,i w\ld especially ref] to ! b>e precipit\s sides ( ! long n>r[ isl&s ( ,kals & ,kun1 z admirable sections :]e9 ! *>act]s ( ! plateau-basalts are reveal$ z 9 a s]ies ( gigantic diagrams4 ,! sc>city ( vegetation1 & ! /eepness ( ! declivities :i* prev5ts ! abundant accumulation ( screes ( detritus1 enable ! obs]v] to trace individual b$s ( basalt ) ! eye = sev]al miles4 ,?us on ! we/ side ( ,kun1 "o conspicu\s d>k %eet 9 ! l[] "p ( ! section c be foll[$ f opposite ,mygl$ahl 9 ,kals to ! s\!rn end ( ! isl&4 ,!re is "o conceal$ space at ! m\? ( ! corrie beh9d ,kun village1 b ! same1 or at lea/ a simil> b& ( rock at ! same level1 em]ges f ! detritus on ! fur!r side1 & may possibly run into ! opposite promontory ( ,bod4 ,x ext5ds 9 ,kun = at lea/ six geographical miles4 ,illu/ration3 ,fig4 #bhh4--;,dy+ out ( ,lava-b$s1 ea/ side ( ,s&1 ,f>oe ,isles4 ,^! va/ esc>pm5ts ( nak$ rock %[1 ) ev5 great] cle>ness ?an ! precipices ( ! ,inn] ,hebrides1 h[ frequ5tly ! basalts die out1 n[ 9 "o direction n[ 9 ano!r4 ,! two sides ( ! ,kalsfjord exhibit _m examples ( ?is /ructure1 & "s /rik+ in/ances ( x are to be se5 on ! we/ side ( ,h>aldsfjord4 ,9 ^! cliffs1 :i* mu/ be ab\t #bjjj feet high1 upw>ds ( =ty di/9ct fl[s c sometimes be trac$ f ! sea-level to ! cre/4 ,! av]age ?ickness ( ea* b$ is ?us some:at less ?an #ej feet4 ,su* va/ esc>pm5ts1 ) wide semicircul> corries scoop$ out ( _! sides1 su* s]rat$ cre/s & d>k rifts 9 ! precipices1 su* deep fjords w9d+ ?r\gh ne>ly horizontal basalts1 ( :i* ! p>allel %eets c be foll[$ by ! eye f isl& to isl&1 fill ! m9d ) a vivid conception at once ( ! enorm\s scale ( ! volcanic eruptions & ( ! /up5d\s d5udation :i* ?is portion ( ,nor?-,we/]n ,europe has und]gone s9ce ,t]ti>y "t4 ,z ! l5ticul> "* ( ! basalts1 & ! evid5ce !y supply ( hav+ be5 dis*>g$ f _m small local v5ts are ( great importance 9 ! compreh5sion ( ! volcanic hi/ory ( ! plateaux1 "s fur!r illu/rations ( ^! features may ) advantage be giv5 "h4 ,?us ! travell] :o skirts ! we/]n precipices ( ,sud] w notice "s good examples to ! nor? ( ! highe/ "p ( ! cliffs4 ,on ,/rom he w detect o!r cases ( ! same /ructure4 ,simil> features w arre/ 8 att5tion on ! precipices ( ,s&1 :]e1 ?\gh at fir/ sight ! basalts seem to be regul> & cont9u\s1 a ne>] view ( !m reveals su* sections z t %[n 9 ,fig4 #bhh1 :]e a gr\p ( %eets rapidly dies out t[>ds ! nor? aga9/ a ?ick] b& t ?9s away 9 ! opposite direction4 ,fur!r nor? he w come ^u o!r examples 9 ! range ( l[ cliffs betwe5 ,kirkebonaes & ,?or%av51 & m impressive /ill 9 ! rugg$ precipices t front ! ,atlantic on ! we/]n front ( ,he/ 7,fig4 #bhi71 :]e ! disappe>ance is 9 a nor!rly direction4 ,illu/ration3 ,fig4 #bhi4--,l5ticul> lavas1 we/]n front ( ,he/1 ,f>oe ,isles4 ,b x is 9 ! nor!rn "p ( ! ,f>oes1 :]e ! basalt-plateau has be5 s deeply tr5*$ by p>allel fjords z to be brok5 up into a gr\p ( long1 n>r[1 l(ty1 & precipit\s insul> ridges1 t ! really local & non-p]si/5t "* ( ! lavas c be/ be se54 ,! ea/]n cliffs ( ,sv9 pres5t admirable examples1 :]e 9 ! same v]tical wall ( rock "s ( ! basalts die out to ! s\?1 o!rs to ! nor?1 :ile occasionally a %ort] %eet may be se5 to disappe> 9 bo? directions z if x 7 ! end ( a /ream t fl[$ at "r angles to ! o!rs 7,fig4 #bij74 ,illu/ration3 ,fig4 #bij4--,l5ticul> lavas ea/ side ( ,sv91 ,f>oe ,isles4 ,! m ! basalt-plateaux ( ,brita9 & ! ,f>oe ,isl&s are /udi$1 ! m c]ta9 does ! conclusion become t ^! widespread %eets ( lava nev] fl[$ f a few l>ge c5tral volcanoes ( ! type ( ,etna or ,vesuvius1 b 7 emitt$ f innum]able m9or v5ts or f op5 fissures4 ,9 a lat] *apt] an acc\nt w be giv5 ( ! v5ts1 :i* may /ill be se5 "u ! ov]ly+ %eets ( basalt1 &1 9 p>ticul>1 a rem>kable gr\p 9 ! ,f>oe ,isl&s w be describ$4 ,illu/ration3 ,fig4 #bia4--,section at ,frodbonyp1 ,sud]1 ,f>oe4 ,! occurr5ce ( tuffs1 leaf-b$s & ?9 coals betwe5 ! plateau-basalts ( ! ,f>oe ,isl&s has long be5 kn[n4 ,^! /ratifi$ deposits are well se5 9 ! isl& ( ,sud]1 :]e !y s]ve to divide two di/9ct s]ies ( basalts1 l ! iron-ore & its accompanim5ts 9 ,antrim4 ,z a *>act]i/ic illu/ration ( ! same div]sity ( deposits obs]vable betwe5 ! lava-%eets ( ! basalt-plateaux ( ! ,briti% ,isles ,i give "h a section expos$ on ! ea/ side ( ?is isl&--a locality (t5 visit$ & describ$ 9 connexion ) its coal-seams 7,fig4 #bia74 ,at ! base lies a %eet ( basalt 7a7 ) an irregul>ly lumpy upp] surface4 ,x may be rem>k$ t ! l[] gr\p ( basalts is m>k$ by ! occurr5ce ( num]\s column> %eets1 "s ( !m possibly sills1 & also m massive1 solid1 & durable basalts ?an ! %eets above4 ,! l[e/ ( ! int]calat$ s$im5ts are light-col\r$ clays1 pass+ d[n into d>k nodul> mud/one & d>k %ale1 ! :ole hav+ a ?ickness ( at lea/ #bj feet 7b74 ,^! /rata are succe$$ by 7c7 pale clays ) black plant-rema9s1 ab\t ?ree feet ?ick4 ,imm$iately above ?is b& comes ! coal or coaly lay] 7d71 "h ab\t six in*es ?ick1 :i* improves 9 ?ickness & quality fur!r inl&1 :]e x has be5 occasionally work$ = economic purposes4 ,a deposit ( gre5 & br[n volcanic mud/one 7e71 twelve feet 9 ?ickness1 ov]lies ! coal & passes "u a well-b$d$ granul> gre5 tuff & mud/one ?ree feet ?ick 7f74 ,! upp]mo/ b& is ano!r volcanic mud/one 7g7 f\r feet 9 ?ickness1 d>k gre5 9 col\r1 & m or less di/9ctly /ratifi$1 ) irregul> concretions1 & also pieces ( wood4 ,above ?is lay] comes ano!r ?ick ov]ly+ gr\p ( basalts 7h7 di/+ui%$ by _! abundantly amygdaloidal "*1 & by _! wea!r+ into globul> =ms :i* at a little di/ance give !m a resemblance to agglom]ates4 ,we h "h an int]calat$ gr\p ( /rata upw>ds ( #dj feet ?ick1 consi/+ p>tly ( tuffs & p>tly ( f9e clays1 :i* may ei!r h be5 d]iv$ f volcanic explosions or f ! atmosph]ic dis9tegration ( basaltic lavas4 ,?r\gh "s ( ^! /rata abundant c>bonace\s /reaks & o!r traces ( plants are di/ribut$1 :ile among !m lies a b& almo/ :olly compos$ ( compress$ vegetation4 ,un=tunately none ( ! /rata at ?is locality seem to h pres]v$ ! plant-rema9s ) suffici5t def9it5ess = id5tification4 ,!re c be no d\bt1 h[ev]1 t !y 7 t]re/rial =ms l ^? ( ,mull & ,antrim4 ,?is coal1 ) its accompany+ s$im5t>y deposits1 has be5 trac$ ?r\gh ,sud]1 & ano!r outcrop1 possibly ( ! same horizon1 occurs on ,mygg5aes1 ! extreme we/]n memb] ( ! gr\p ( isl&s1 at a di/ance ( "s #dj miles4#bff ,footnote #bff3 ,see 9 p>ticul> ,pr(4 ,j4 ,geikie1 ,trans4 ,roy4 ,soc4 ,ed94 vol4 xxx4 7#ahhj71 p4 #bbi4 ,,*apt] ,,xl ,,! ,,mod]n ,,volcanoes ,,( ,,icel& ,,z ,,illu/rative ,,( ,,! ,,t]ti>y ,,volcanic ,,hi/ory ,,( ,,nor?-,,we/]n ,,europe ,f ! facts /at$ 9 ! =ego+ *apt]s conc]n+ ! /ructure ( ! basalt-plateaux ( ,nor?-,we/]n ,europe1 x is evid5t t 9 none ( ^! areas h ! eruptions come f "o great c5tral volcano l ,etna or ,vesuvius4 ,on ! contr>y1 9 e in/ance !re is abundant evid5ce t ! basalt has fl[$ f _m scatt]$ po9ts ( eruption4 ,! uni=mity ( ! lava-%eets 9 petrographical *>act]s1 _! cont9uity :5 view$ 9 mass1 _! g5]al horizontality1 & _! con/ant ?9n+ away 9 diff]5t directions1 %[ t ! eruptive v5ts mu/ h be5 di/ribut$ ov] ! :ole plateau-areas4 ,! conditions "u :i* su* eruptions took place c be mo/ readily und]/ood by a comp>ison ( ! ph5om5a ) ^? obs]vable 9 mod]n volcanic tracts :]e ext5sive outfl[s ( lava h tak5 place )\t ! exi/5ce ( any great c5tral cones4 ,( ^! regions ! mo/ in/ructive is und\bt$ly to be f\nd among ! rec5t lava-des]ts ( ,icel&4 ,!re ! p>allels to ! /ructures describ$ f ! ,briti% & ,f>oe plateaux are s num]\s & s close t an acc\nt ( ! ,icel&ic region may appropriately be ins]t$ "h4 ,! evid5ce furni%$ by ,icel& is ( special value 9 our pres5t enquiry1 inasmu* z t isl&1 besides its mod]n eruptions1 includes va/ basaltic plateaux ( ,t]ti>y age4 ,^! areas ( ne>ly level %eets ( basalt belong to ! same geological p]iod z ^? ( ! ,briti% & ,f>oe ,isl&s1 & display ! same int]nal /ructure & ext]nal features4 ,b !y h ?is di/+ui%+ peculi>ity t ! volcanic fires b5ea? !m are n yet ext+ui%$4 ,!y h be5 brok5 ?r\gh aga9 & aga9 9 rec5t times by volcanic eruptions :i* h repeat$ _m ( ! *>act]i/ics ( _! ,t]ti>y pr$ecessors4 ,! old & ! new developm5t ( ! same volcanic type are ?us visible side by side4 ,! ,t]ti>y volcanic s]ies ( ,icel& rea*es a ?ickness ( upw>ds ( #cjjj metres1 or ne>ly #aj1jjj ,engli% feet1 b z its base is n[h]e se51 x may be /ill ?ick]4 ,its successive %eets1 pil$ ov] ea* o!r 9 p>allel lay]s1 =m t]rac$ hills & bold esc>pm5ts along ! coa/1 :5ce !y slope g5tly inl&4 ,! plateau1 z 9 ! ,f>oe ,isl&s & 9 ,scotl&1 has be5 ext5sively erod$1 & has be5 tr5*$ by _m long valleys & fjords ,! composition ( ! basalts rema9s rem>kably uni=m ov] ! isl&4 ,! lava %eets are (t5 decompos+1 amygdaloidal1 & fill$ ) zeolites2 :ile high] 9 ! s]ies compact basalts ab\nd1 ! upp]mo/ f9e-gra9$ %eets be+ especially con/ant 9 /ructure & composition4 ,num]\s dykes trav]se ! plateau1 & "s ( !m cut ev5 its highe/ memb]s4 ,! p>allel ) ! geological /ructure ( ! ,inn] ,hebrides is cont9u$ 9 ,icel& by ! appe>ance ( intrusive masses ( gabbro & granophyre1 :i* repres5t ! deep] p>ts ( ! ,t]ti>y volcanic s]ies1 :ile ! basalts 7 p\r$ out at ! surface4 ,?us1 at ,papafjord1 ! gabbro rises into m\nta9\s peaks &1 l ! simil> rock 9 ,mull & ,skye1 is int]sect$ by dykes ( a co>se-gra9$ granitoid lip>ite or granophyre4 ,l>ge dykes & ramify+ ve9s ( ! same acid mat]ial1 (t5 ) a ?or\ghly granitic aspect1 ext5d into ! basalts4#bfg ,footnote #bfg3 ,mr4 ,?orodds51 ,dansk4 ,geografisk ,tidsskrift1 vol4 xiii4 ,a long s]ies ( eruptions has tak5 place 9 ,icel& s9ce ! ,glacial ,p]iod4 ,!re 7 likewise pre-glacial eruptions4 ,! glaciat$ lava-/reams are f\nd und]nea? ! mod]n lavas4 ,s f> inde$ z is kn[n1 no evid5ce exi/s ( any important cessation ( subt]ranean activity !re s9ce ,t]ti>y "t4#bfh ,! exi/+ volcanic ph5om5a may ) probability be reg>d$ z ! survival ( ^? :i* 7 s widely manife/$ ov] ! ,icel&ic area & ! nor?-we/ ( ,europe 9 ! old] ,t]ti>y ages4 ,a c>eful /udy ( !m may !re=e be expect$ to ?r[ light on ! hi/ory ( ! ,t]ti>y basaltic plateaux2 :ile1 on ! o!r h&1 ! ?or\gh dissection ( ^! plateaux by ! d5ud+ ag5cies w n improbably be f\nd to expla9 "s p>ts ( ! subt]ranean me*anism ( ! mod]n ,icel&ic volcanoes4 ,footnote #bfh3 ,see ,dr4 ,john/on-,lavis1 ,scotti% ,geographical ,magaz9e1 #ahie1 p4 #ddb4 ,9 call+ att5tion to "s ( ! m obvi\s analogies :i* may be trac$ betwe5 ! mod]n & ! anci5t volcanoes1 ,i am m p>ticul>ly indebt$ to ! excell5t memoirs ( ! resid5t ,icel&ic geologi/1 ,mr4 ,?4 ,?orodds51 :o has exam9$ s l>ge a "p ( ! isl&4#bfi ,! acc\nt giv5 by ,mr4 ,a4 ,holl& ( ! ,laki crat]s has likewise be5 ( mu* s]vice to me4#bgj ,among o!r rec5t obs]v]s ,i may cite ,dr4 ,tempe/ ,&]son1#bga :o has made himself famili> ) ext5sive tracts ( ,icel&4 ,he 0 accompani$ "o ye> by ,dr4 ,john/on-,lavis1 :o has publi%$ a n>rative ( ! j\rney4#bgb ,footnote #bfi3 ,see ,9 p>ticul> 8 pap] on ! volcanoes ( nor?-ea/ ,icel& 7,bihang till4 k4 ,sv5sk4 ,vet4 ,akad4 ,h&l4 xiv4 ii4 ,no4 #e1 #ahhh7 & t on ,snaefell & ,faxebugt 9 ! s\?-we/ ( ! isl& 7op4 cit4 xvii4 ii4 ,no4 #b1 #ahia72 also pap]s 9 ,dansk4 ,geografisk ,tidsskrift1 vols4 xii4 xiii4 7#ahic-ie72 ,v]h&4 ,gesells*4 ,erdkunde zu ,b]l91 #ahid-ie4 ,footnote #bgj3 ,lakis ,krat]e og ,lava/rmme1 ,univ]sittsprogram1 ,*ri/iania1 #ahhe4 ,see ,mr4 ,?orodds5's rem>ks on ?is pap]1 ,v]h&4 ,gesell4 ,erdkunde1 #ahid1 p4 #bhi4 ,footnote #bga3 ,brit4 ,assoc4 ,rep4 #ahid1 p4 #fej4 ,footnote #bgb3 ,dr4 ,john/on-,lavis1 ,scotti% ,geographical ,magaz9e1 ,septemb] #ahie4 ,x is a mi/ake to suppose t ! ,icel&ic volcanoes are g5]ally built on ! plan ( su* m\nta9s z ,vesuvius or ,etna4 ,mr4 ,?orodds5 c evid5tly h>dly repress 8 impati5ce to f9d ^! two ,italian cones cit$ 9 almo/ e h&book ( geology z types ( mod]n volcanoes & _! op]ations4 ,! regul> volcanic cone1 compos$ ( alt]nations ( lavas & tuffs1 plays a v subord9ate "p 9 ,icel&4 ,illu/ration3 ,fig4 #bib4--;,fissure 7gj7 9 a lava-field1 ,icel&4 7,f a photograph by ,dr4 ,tempe/ ,&]son47 ,! fundam5tal feature 9 ! ,icel&ic eruptions is ! production ( fissures :i* rea* ! surface & dis*>ge /reams ( lava f _m po9ts4 ,two sy/ems ( su* fissures appe> to be specially m>k$1 "o 9 s\!rn ,icel& runn+ f s\?-we/ to nor?-ea/1 ! o!r1 9 ! nor? "p ( ! isl&1 /ret*+ f s\? to nor?4#bgc ,hekla & ,laki belong to ! =m]4 ,! dislocations h (t5 foll[$ ! b\nd>ies ( ! hor/s1 or solid blocks ( c\ntry :i* h )/ood t]re/rial displacem5t4 ,! va/ outbreaks ( ,oddahraun & ,myvatn h almo/ all issu$ f fissures ( t nature4 ,footnote #bgc3 ,9 ! ,snaefell promontory !y run ne>ly ea/ & we/4 ,mr4 ,?orodds51 ,bihang4 ,sv5sk4 ,akad4 xvii4 7ii47 ,no4 #b1 p4 #ia4 ,! viol5t eruption ( #ahge 9 ,askja f\nd its exit at ! int]section ( two l9es ( fissures4 ,_m l>ge fissures 7 op5$ on ! surface 9 a ne>ly nor? & s\? direction1 :i* c\ld be foll[$ = #hj kilometres or ne>ly #ej ,engli% miles4 ,"s ( !m became ! !atre ( int5se volcanic activity4#bgd ,footnote #bgd3 ,mr4 ,?orodds51 op4 cit4 xiv4 ii4 ,no4 #e1 p4 #fc4 ,_m l9es ( fissure are traceable at ! surface z clefts or gjs1 t run ne>ly /raight = long di/ances1 ) a wid? ( "o to ?ree y>ds1 & sometimes ( unkn[n dep?4#bge ,! mo/ /up5d\s example ( ! /ructure yet discov]$ is probably ! ,eldgj f\nd by ,dr4 ,?orodds5 9 ! ye> #ahic1 bel[ ! ,mrdalsjkull4 ,?is gigantic *asm has a l5g? ( #cj kilometres 7m ?an #ah ,engli% miles71 & a dep? ( #acj to #bjj metres 7#dbf to #fef feet74 ,ov] its v]tical walls l(ty wat]falls plunge f ! cre/ to ! bottom4 ,footnote #bge3 ,on ! v>i\s modes ( orig9 ( ^! *asms1 see ,dr4 ,tempe/ ,&]son1 ,brit4 ,assoc4 ,rep4 p4 #fej4 ,! gj %[n 9 ,fig4 #bib is n an eruptive fissure4 ,= ?is & ! foll[+ illu/ration ,i am indebt$ to ! k9dness ( ,dr4 ,tempe/ ,&]son1 :o himself photograph$ ! sc5es4 ,occasionally a fissure has n be5 cont9u\sly op5$ to ! surface4 ,an int]e/+ example ( su* int]mitt5t *asms is suppli$ by ! great r5t :i* gave =? ! enorm\s volume ( lava 9 #aghc4 ,! m\nta9 ( ,laki1 compos$ ( palagonite tuff1 /&s on ! l9e ( ?is dislocation1 b has n be5 entirely ruptur$4 ,! fissure has clos$ up b5ea? ! m\nta91 a %ort di/ance above ! bottom ( ! slope1 z is %[n by ! position ( a c\ple ( small crat]s4#bgf ,footnote #bgf3 ,mr4 ,a4 ,hell&1 op4 cit4 p4 #be4 ,"s fissures h rema9$ m]e op5 *asms )\t any dis*>ge ( volcanic mat]ial2 o!rs h s]v$ z passages = ! escape ( lava & ! ejection ( loose slags & c9d]s4#bgg ,footnote #bgg3 ,mr4 ,?orodds5 has obs]v$ t 9 ! ,reykjanes p59sula 9 ! s\?-we/ ( ,icel&1 by ! subsid5ce ( "o side ( a fissure1 a r[ ( f\r crat]s has be5 cut ?r\gh1 leav+ _! segm5ts p]*$ ^u ! upp] side4 ,globus4 vol4 lxix4 ,no4 #e4 ,illu/ration3 ,fig4 #bic4--;,cones on ! great ,laki fissure1 ,icel&4 7,f a photograph by ,dr4 ,tempe/ ,&]son47 ,9 "s in/ances1 accord+ to ,mr4 ,?orodds51 lava wells out f ! :ole l5g? ( a fissure )\t giv+ rise to ! =mation ( cones1 ! molt5 mat]ial issu+ ei!r f "o or f bo? sides & fl[+ out tranquilly4 ,?us f ?ree po9ts on ! great ,eldgj *asm lava spread out quietly )\t giv+ rise to any crat]s1 ?\gh at ! s\!rn prolongation ( ! fissure1 :]e x becomes n>r[]1 a r[ ( l[ slag-cones 0 =m$4 ,! ?ree lava-/reams flood$ ! l[ gr\nd ov] an area ( #fic squ>e kilometres1 or #bgj ,engli% squ>e miles4 ,9 ! great majority ( cases1 h[ev]1 ! lava z x asc5ds 9 ! fissure gives rise to long ramp>ts ( slags & blocks ( lava pil$ up on ei!r side1 or to a r[ ( cones along ! l9e ( ! op5 *asm4 ,?us1 on ! ,laki fissure1 :i* runs = ab\t #bj miles 9 a nor?-ea/ direction1 ! cones am\nt to "s hundr$s 9 numb]4 ,illu/ration3 ,fig4 #bic;a4--,plan ( small crat]s along ! l9e ( great ,laki fissure1 ,icel&4 7,aft] ,mr4 ,hell&1 r$uc$47 ,! cones consi/ g5]ally ( slags1 c9d]s1 & blocks ( lava4 ,!y are on ! :ole n q circul> b oblong1 _! major axis co9cid+ ) ! l9e ( ! *asm on :i* !y h be5 pil$ up1 z along ! m>vell\s l9e ( ! ,laki fissure4 ,9 _m places !y are exce$+ly irregul> 9 =m1 *anges 9 ! direction ( outfl[ ( lava or ( escape ( /eam hav+ caus$ ! cones p>tially to efface ea* o!r4 ,z reg>ds _! size1 ! cones pres5t a wide range4 ,"s ( !m are only a few y>ds 9 diamet]1 o!rs sev]al hundr$ y>ds4 ,g5]ally !y are comp>atively l[ m\nds4 ,on a fissure h>dly #cj feet long1 ,mr4 ,?orodds5 f\nd a r[ ( twelve small cones built exactly l ^? ( l>ge/ size1 b ) crat]s less ?an ?ree feet 9 diamet]4 ,on ! ,laki fissure "s are only a c\ple ( y>ds high2 ! majority are mu* less ?an #ej y>ds 9 height1 & h>dly "o is z mu* z #ajj y>ds4#bgh ,& yet ^! little monticules1 z ,mr4 ,hell& rem>ks1 repres5t ! pipes f :i* milli>ds ( cubic metres ( lava h issu$4 ,:ile o!r ,european volcanoes =m conspicu\s features 9 ! l&scape1 ! ,icel&ic volcanoes ( ! ,laki di/rict1 f :i* ! va/e/ floods ( lava h issu$ 9 mod]n times1 are s l[ t !y might escape notice unless !y 7 actually s\ght =4#bgi ,footnote #bgh3 ,mr4 ,?orodds51 h[ev]1 /ates t !re are ab\t #ajj rang+ betwe5 #bj & #ajj metres 9 height4 ,footnote #bgi3 ,op4 cit4 p4 #bg4 ,z !y h g5]ally aris5 along l9es ( fissure1 ! cones are1 = ! mo/ "p1 gr\p$ 9 r[s4 ,! hundr$s ( cones t m>k ! l9e ( ! ,laki fissure pres5t an extraord9>y picture ( volcanic en]gy ( ?is type4 ,9 o!r in/ances ! cones occur 9 gr\ps1 ?\gh ?is di/ribution may h aris5 f ! irregul> uprise ( scatt]$ v5ts along a s]ies ( p>allel fissures4 ,?us to ! nor?-ea/ ( ,laki a s]ies ( old cones entirely surr\nd$ by ! lavas ( #aghc lie 9 gr\ps1 ! mo/ nor!rly ( :i* consi/s ( ab\t #ajj exce$+ly small crat]s t h s5t out /reams ( lava t[>ds ! ,n4,n4,e4#bhj ,footnote #bhj3 ,op4 cit4 p4 #be4 ,! great lava-fields ( ,icel& are likewise dott$ ov] ) second>y crat]s or hornitos :i* h no direct connection ) ! magma bel[1 b arise f local causes affect+ ! outfl[+ lava4 ,!y are gr\p$ 9 hundr$s ov] a small space4 ,x w\ld appe> f ,mr4 ,hell&'s obs]vations t ! same fissure has sometimes be5 made use ( at m ?an "o p]iod ( eruption4 ,he describes "s old crat]s on ! l9e ( ! ,laki fissure1 :i* _h be5 active long be=e ! outbreak ( #aghc4bha ,footnote #bha3 ,op4 cit4 p4 #bf4 ,:5 ! lava issues f fissures x is 9 su* a condition ( pla/icity t x c be drawn out into ?reads & spun into ropes4 ,:5 ! slope ov] :i* x fl[s is /eep x (t5 splits up into blocks on ! surface4 ,:]e ! gr\nd is flat ! lava spreads out uni=mly on all sides1 =m+ wide pla9s z level z a floor4 ,?us ! va/ lava-des]t ( ,oddahraun cov]s a pla9 #cfdj squ>e kilometres 9 area1 or1 if ! small-lava-/reams nor? f ,vatnajkull be includ$1 #dcij squ>e kilometres4 ,?is va/ flood ( lava 7ab\t #agjj ,engli% squ>e miles 9 ext5t7 w\ld1 accord+ to ,mr4 ,?orodds51 cov] ,d5m>k to a dep? ( #af feet4 ,! :ole ( ?is enorm\s dis*>ge has be5 giv5 =? f m ?an tw5ty v5ts situat$ = ! mo/ "p on p>allel fissures4 ,n less /rik+ is ! picture ( fissure-eruption to be met ) at ,laki--! sc5e ( ! great lava-floods ( #aghc4 ,conceive n[1 says ,mr4 ,hell&1 ^! hundr$s ( crat]s1 or1 z !y are call$ by ! ,icel&]s1 'borge1' ly+ "o beh9d ano!r 9 a long r[2 e "o ( !m hav+ s5t out two or m /reams ( lava1 n[ to ! "o side1 n[ to ! o!r4 ,und]/& fur!r t ^! /reams m]ge into ea* o!r1 s z to fl[ :olly r\nd ! cones & =m fields ( lava miles 9 wid?1 :i*1 l va/ froz5 floods1 fl[ d[n to ! c\ntry di/ricts1 & y may =m "s idea ( ?is rem>kable region4#bhb ,footnote #bhb3 ,op4 cit4 p4 #bd4 ,mr4 ,hell& all[s an av]age ?ickness ( #cj metres = ! mass ( lava :i* issu$ 9 two /reams1 "o #hj kilometres 7ne>ly #ej miles71 ! o!r #de kilometres 7ab\t #bh miles7 long4 ,he e/imates ! total volume ( lava dis*>g$ 9 ! #aghc eruption at #bg milli>ds ( cubic metres1 equal to a block #aj kilometres 7#f miles #cgf y>ds7 long1 #e kilometres 7#c miles #ahh y>ds7 broad1 & #edj metres 7#agga feet7 high2 op4 cit4 p4 #ca4 ,mr4 ,?orodds5 rem>ks t ! old] e/imates ( ! volume ( lava dis*>g$ by ?is eruption h be5 greatly exagg]at$4 ,he puts ! area cov]$ by lava at #efe squ>e kilometres & ! cont5ts at #ab-a_/c cubic kilometres4 ,v]h&4 ,gesell4 ,erdkunde ,b]l91 #ahid1 p4 #bif4 ,! basaltic lavas h issu$ 9 a comp>atively liquid /ate1 =m ?9 %eets & rea* to great di/ances4 ,! we/]n /ream f ! ,laki eruption ( #aghc fl[$ = upw>ds ( #dj miles2 a prehi/oric lava f ,trlladyngj 9 ,oddahraun fl[$ = m ?an #fj miles4 ,9 ! c\rse ( "t ! successive /reams ( lava p\r$ out ^u "o ( ^! wide volcanic pla9s gradually increase ! height ( ! gr\nd1 :ile pres]v+ its g5]ally level aspect4 ,! loose slag-cones ( e>li] eruptions are effac$ or swall[$ up1 z "o lava-/ream foll[s ano!r4 ,ev5tually1 :51 by ! op]ation ( runn+ wat] or by fissure & subsid5ce1 transv]se sections are cut ?r\gh ^! lava-%eets1 ! obs]v] c g5]ally notice only horizontal b$s ( lava pil$ "o above ano!r1 includ+ ! dykes connect$ ) !m & int]calat$ masses ( loose slag1 t rema9 z relics ( ! old crat]s4 ,9 "s places ! lava has gradually built up enorm\s domes1 l ^? ( ,hawaii1 hav+ a g5tle incl9ation 9 e direction1 z may be se5 especially 9 ! di/rict betwe5 ,flod]ne ,skjalfanafljot & ,jkuls ,mo/ ( ! l>ge volcanic piles ( ,nor? ,icel& are ( ?is nature4 ,! highe/ ( !m are #abji & #adia metres high by f #f to #ae kilometres 9 diamet]4 ,! elliptical crat] ( ! highe/ ( ^! em95ces measures #aajj by #chj metres4#bhc ,footnote #bhc3 ,mr4 ,?orodds51 op4 cit4 xiv4 ii4 ,no4 #e1 pp4 #aj1 #bc4 ,l>ge conical volcanoes ( ! ,vesuvian type built up ( alt]nat+ lavas & tuffs are n common 9 ,icel&1 b "s occur & rise into l(ty glaci]-cov]$ m\nta9s1 su* z rfajkull 7#fbda feet71 ,eyjafjallajkull 7#edcb71 & ,snaefellsjkull 7#degg74 ,hekla 7#difa7 also is simil>ly compos$ ( %eets ( lava & tuffs1 b has n be5 built z a cone4 ,x =ms an oblong ridge :i* has be5 fissur$ 9 ! direction ( its l5g? & be>s a r[ ( crat]s along ! fissure4#bhd ,footnote #bhd3 ,mr4 ,?orodds51 ,dansk4 ,geograf4 ,tidsskrift1 vol4 xiii4 ,explosion-crat]s likewise occur among ! mod]n volcanic ph5om5a ( ,icel&4 ,"o ( ^! 0 =m$ by a viol5t explosion at ,askja on #bi? ,m>* #ahge4 ,x has a diamet] ( only ab\t #bhj feet1 yet s great 0 ! vig\r ( ! outbur/ t pumice\s /ones 7 spread ov] an area ( m ?an #ajj ,dani% 7#dfh ,engli%7 squ>e miles1 & ! du/ 0 c>ri$ z f> z ,norway & ,sw$54 ,n9e ye>s lat] ,mr4 ,?orodds5 f\nd ! bottom ( ?is crat] fill$ ) blui%-gre5 boil+ mud1 :i* w probably 9 ! end become a %eet ( /ill wat]4 ,! bord]s ( ^! ,icel&ic explosion-crat]s seem to be v little high] ?an ! gr\nd ar\nd !m4 ,mo/ ( ! eject$ mat]ial is expell$ ) su* =ce & to su* a di/ance t only a small fraction ( x falls d[n ar\nd ! orifice ( eruption4#bhe ,footnote #bhe3 ,mr4 ,?orodds51 op4 cit4 ,!re is /ill ano!r feature ( ! ,icel&ic volcanic regions :i* may be cit$ z an int]e/+ p>allel to ! sequ5ce ( eruptive dis*>ges among ! ,inn] ,hebrides4 ,:ile ! lavas are z a rule m or less basic--_m ( !m be+ true basalts--!y h be5 at diff]5t times pi]c$ by mu* m acid lip>ites & obsidians4 ,examples ( ^! rocks ( po/-,glacial age h rec5tly be5 trac$ on ! gr\nd by ,mr4 ,?orodds51#bhf & _! petrographical *>act]s h be5 /udi$ by ,mr4 ,bck/rm4#bhg ,! wide di/ribution ( su* rocks all ov] ! isl&1 _! occurr5ce 9 isolat$ bosses among ! m basic lavas1 & _! rem>kable int]nal /ructures h be5 not$ by sev]al obs]v]s4#bhh ,! lip>ites & obsidians are contra/$ ) ! basalt by ! col\rs & =ms ( _! /reams4 ,"s ( !m are s black z to look l heaps ( coal1 ?\gh _! surfaces pass into grey pumice4 ,!y h fl[$ out 9 a mu* less liquid condition ?an ! basalts1 & h consequ5tly =m$ %ort1 ?ick & irregul> %eets4 ,! lip>ites & basalts appe> to h be5 ne>ly contemporane\s4 ,!y c]ta9ly belong to ! same volcanic cycle & _! v5ts lie close to ea* o!r4 ,?\gh none ( ! acid eruptions are kn[n to h occurr$ 9 mod]n times1 "s ( ! lip>ites are cru/$ ) sulphur & f ! connect$ fissures /eam /ill rises4 ,footnote #bhf3 ,geol4 ,fr54 ,/ockholm ,frh&l4 xiii4 7#ahia71 p4 #fji2 ,bihang4 ,sv5sk4 ,vet4 ,akad4 ,h&l4 xvii4 ii4 p4 #ba 7#ahia72 ,dansk4 ,geograf4 ,tidsskrift1 xiii4 7#ahie74 ,footnote #bhg3 ,geol4 ,fr54 ,/ockholm ,frh&l4 xiii4 7#ahia71 p4 #fcg4 ,footnote #bhh3 ,see 9 p>ticul> ,c4 ,w4 ,s*midt1 ,zeits*4 ,deuts*4 ,geol4 ,gesells*4 xxxvii4 7#ahhe71 p4 #gcg4 ,x w ?us be se5 h[ entirely ! mod]n volcanic eruptions ( ,icel& agree ) ! ph5om5a pres5t$ by our ,t]ti>y basalt-plateaux4 ,x is1 !re=e1 to ! ,icel&ic type ( fissure-eruptions1 & n to great c5tral composite cones l ,vesuvius or ,etna t we mu/ look = ! mod]n analogies t w be/ s]ve z comm5t>y & explanation = ! late/ *apt] 9 ! long volcanic hi/ory ( ! ,briti% ,isles4#bhi ,footnote #bhi3 ,9 8 memoir ( #ahgd1 ,pr(essor ,judd ann\nc$ 8 conclusion t !re 7 =m]ly five great volcanoes among/ ! ,we/]n ,isles1 & t ! lavas ( ! plateaux _h issu$ f ^!4 ,he subsequ5tly reit]at$ ?is view 7,qu>t4 ,j\rn4 ,geol4 ,soc4 xlv41 #ahij1 p4 #ahg71 & ridicul$ ! explanation ( fissure-eruptions4 ,! evid5ce adduc$ by me 9 a pap] publi%$ 9 #ahif 7same j\rnal1 vol4 lii4 p4 #cca7 & repr9t$ ) additions 9 ?is *apt]1 w1 ,i tru/1 be reg>d$ by geologi/s z hav+ f9ally settl$ ?is "q4 ,z a fur!r b m anci5t illu/ration ( ! type ( volcanic action :i* appe>s to h be5 preval5t dur+ ! =mation ( ! ,t]ti>y volcanic plateaux ( ,brita91 ,i may aga9 ref] to ! va/ basalt-fields ( ,we/]n ,am]ica4 ,! basalt ( ,idaho /ret*es out z an app>5tly limitless pla94 ,along its nor!rn b\nd>y1 ?is sea ( black lava runs up ! valleys & r\nd ! promontories ( ! old] tra*ytic hills ) almo/ ! flatness ( a %eet ( wat]4 ,x has be5 deeply tr5*$1 h[ev]1 by ! /reams t w9d across x1 & especially by ! ,snake ,riv]1 :i* has cut out a gorge "s #gjj feet deep1 on ! walls ( :i* ! successive b$s ( basalt lie horizontally "o ^u ano!r1 w9d+ along ! curv+ face ( ! precipice exactly z ^? ( ,antrim & ! ,inn] ,hebrides d along _! sea-worn esc>pm5ts4 ,"h & !re1 a l[ c9d]-cone on ! surface ( ! pla9 m>ks ! site ( a late outfl[4 ,"o is /ruck1 h[ev]1 ) ! s+ul> abs5ce ( tuffs & volcanic conglom]ates4 ,! basalts appe> to h fl[$ out /ream aft] /ream ) few fragm5t>y dis*>ges4 ,^! *>act]i/ic features ( "o di/9ctive type ( volcanic action h be5 repeat$ ov] a va/ region1 or r a :ole s]ies ( regions1 9 ,we/]n ,am]ica1 ! unit$ area ( :i* mu/ equal t ( a consid]able "p ( ,europe4 ,f ,idaho1 ! basalt-fields may be foll[$ s\?w>ds int]rupt$ly into ,utah & ,nevada1 & across ! great plateau-c\ntry ( ! caons into ,arizona & ,new ,mexico1 nor?w>ds into ,montana1 & we/w>ds into ,oregon4 ,! tract :i* has z yet be5 mo/ c>efully trav]s$ & describ$ is probably t ( ! high plateaux ( ,utah & ,arizona4 ,?us on ! ,u9k>et plateau1 :i* measures "s #de to #ej miles 9 l5g? by #h to #ab 9 bread?1 a ?ick cov]+ ( basalt has be5 spread compos$ ( _m successive fl[s4 ,betwe5 #afj & #agj sep>ate cones h be5 c\nt$ on ?is area1 mo/ ( !m q small1 m]e l[ m\nds ( scori1 ?\gh a few rea* a height ( #gjj or #hjj feet1 ) a diamet] ( a mile4 ,f ?ree to sev5 or eight may be f\nd 9 a r[1 z if spr++ f a s+le l9e ( fissure4 ,b g5]ally ! gr\p+ is q irregul>4#bij ,my fri5d ,capta9 ,c4 ,e4 ,dutton1 f ^: admirable memoir ^! details are quot$1 rem>ks fur!r t among ! ,utah plateaux no trace ( a cone is to be f\nd at or ne> "s ( ! mo/ rec5t basalt-fields1 & t ! mo/ ext5sive outp\rs are mo/ frequ5tly )\t cones4 ,! lavas1 he adds1 appe> to h rea*$ ! surface & ov]fl[$ l wat] f a spr+1 spread+ out imm$iately & delug+ a broad surface ar\nd ! orifice4#bia ,! deep gorges cut by ! riv]s ?r\gh ^! ?ick accumulations ( horizontal or ne>ly horizontal basalts1 h "h & !re reveal$ p>allel dykes t trav]se ! rocks1 & 9 at lea/ "o case h %[n ! dyke runn+ = half a mile up a cliff & actually communicat+ ) a crat] ( scori at ! top4#bib ,aga91 9 ,new ,mexico1 ,capta9 ,dutton notic$ va/ tracts ( y\ng] basalt1 ab\t :i* a /rik+ fact is ! entire abs5ce ( all di/+ui%able traces ( ! v5ts f :i* !y came4 ,"s ( !m1 h[ev]1 indicate unmi/akably _! s\rces 9 small depress$ cones ( v flat pr(iles4 ,no fragm5tal ejecta 7scori1 lapilli1 etc47 h be5 f\nd 9 connection ) ^! "y eruptions4#bic ,su* ,i believe to h be5 ! g5]al conditions "u :i* ! basalts ( ! ,t]ti>y plateaux ( ! ,briti% ,isles 7 also erupt$4#bid ,footnote #bij3 ,capta9 ,c4 ,e4 ,dutton1 ,t]ti>y ,hi/ory ( ! ,gr& ,caon ,di/rict1 ,u4,s4 ,geol4 ,survey 7#ahhb71 p4 #ajd4 ,footnote #bia3 ,capta9 ,c4 ,e4 ,dutton1 ,geology ( ! ,high ,plateaux ( ,utah1 ,u4,s4 ,geol4 ,survey ( ! ,rocky ,m\nta9 ,region 7#ahhj71 pp4 #aih1 #bjj4 ,see also pp4 #bcb1 #bcd1 #bgf ( ! same ,monograph = additional examples4 ,footnote #bib3 ,t]ti>y ,hi/ory ( ! ,gr& ,caon1 etc41 p4 #ie4 ,footnote #bic3 ,nature1 xxxi4 7#ahhd71 p4 #di4 ,footnote #bid3 ,i may aga9 ref] to ,hopk9s's ,rese>*es 9 ,physical ,geology1 :]e ! conditions ( ! problem "h discuss$ h be5 di/9ctly realiz$4 ,speak+ ( ! ejection ( lava f a numb] ( fissures1 he rem>ks t ! imp]fect fluidity ( ! melt$ mat]ial w\ld seem to require a numb] ( po9ts or l9es ( ejection z a necess>y condition4 ,if !re 7 only a s+le c5tre ( eruption1 a b$ ( su* matt] approximat+ to uni=mity ( ?ickness1 c\ld only be produc$ on a surface ( a conical =m4 ,:]e no su* t5d5cy to ?is conical /ructure c be trac$1 x w\ld probably be 9 va9 to look = any s+le c5tre ( eruption4 ,on ! supposition1 too1 ( ejection ?r\gh cont9u$ fissures1 or f a numb] ( po9ts1 t m9or unev5ness ( surface :i* mu/ probably h exi/$ "u all circum/ances dur+ ! =mation ( ! e>?'s cru/1 w\ld n necess>ily de/roy ! cont9uity ( a comp>atively ?9 ext5sive b$ ( ! eject$ matt]1 9 ! same degree 9 :i* x w\ld inevitably produce t effect 9 ! case ( c5tral ejection 7,cambridge ,phil4 ,trans4 vi4 #ahce1 p4 #ga74 ,al?\gh we may be conv9c$1 f _! g5]al /ructure & relations1 t ! /ratifi$ lavas ( ^! plateaux h be5 p\r$ out f fissures & n f great c5tral cones1 x mu/ obvi\sly be difficult to obta9 demon/rative evid5ce ( ?is orig9 f any s+le section4 ,( ! ?\s&s ( dykes :i* trav]se ! ,briti% plateaux & ! gr\nd ar\nd !m1 ,i am n aw>e ( a s+le "o :i* c be actually se5 to h ev] communicat$ ) ! surface4 ,! v process ( d5udation :i* has reveal$ ^! dykes has at ! same "t remov$ all trace ( any =m] connection !y may h _h ) ! surface4 ,! only places :]e we may hopefully se>* = ! miss+ evid5ce are ! fronts ( ! esc>pm5ts4 ,on ^! precipices dykes may sometimes be se5 to end (f at "s p>ticul> plat=m among ! basalt-%eets1 b ,i h nev] f\nd a case :i* c\ld be confid5tly cit$ z an example ( lava ris+ 9 a fissure & spread+ out z a sup]ficial %eet4 ,t ?is connection may ev5tually be f\nd :5 a m detail$ survey is made ( ^! great sea-walls ,i fully anticipate4 ,9 rec5tly mapp+ ! basalt-plateau ( ,/ra?aird 9 ,skye1 ,mr4 ,h>k] has made "s int]e/+ obs]vations reg>d+ ! probable connection ( ! dykes ) ! plateau basalts4 ,he has notic$ t ! flanks ( ,slat ,bhe9n1 a portion ( ! plateau1 are abundantly trav]s$ by dykes conta9+ num]\s enclos$ pieces ( gabbro1 :ile ! basalt on ! summit ( ! plateau is full ( simil> fragm5ts--an occurr5ce n obs]v$ else:]e4 ,x is conceivable t ! gabbro-be>+ basalt-%eets are sills1 b ,mr4 ,h>k] has f\nd no pro( t !y are s1 ! evid5ce s f> z x has be5 collect$ be+ r 9 fav\r ( ! view t ^! %eets are sup]ficial lavas1 & t !y h be5 suppli$ f ! dyke-fissures4 ,v>i\s consid]ations suffice to assure u t actual in/ances ( ! outfl[ ( ! basalt f its p>5t fissures %\ld be expect$ to be exceptional4 ,! abs5ce or sc>city ( b$s ( scori among ! basalt-plateaux may be tak5 z an indication t ! lava z a rule fl[$ out )\t ! =mation ( c9d]-cones1 & !re=e t ^! conspicu\s monum5ts ( ! eruptive v5ts 7 probably always r>e 9 ,brita94 ,if ! lava 0 p\r$ out tranquilly f "o or two po9ts along a fissure :i* 7 subsequ5tly buri$ "u floods ( simil> lava issu+ f o!r fissures1 ! *ances t su* po9ts ( emission %\ld be laid op5 along ! front ( any esc>pm5t are small4 ,&1 ev5 :5 s expos$1 x might be difficult to feel sure t ! dyke bel[ 0 really ! fe$] ( ! basalt above1 unless ! cliff 7 accessible & ! rocks c\ld be scrut9iz$ foot by foot4 ,^! elem5ts ( unc]ta9ty are happily remov$ :]e ! volcanic en]gy has drill$ well-m>k$ funnels ( dis*>ge & left !m fill$ ) ! erupt$ mat]ials1 z w be n>rat$ 9 ! next *apt]4 ,,*apt] ,,xli ,,! ,,eruptive ,,v5ts ,,( ,,! ,,basalt-,,plateaux ,v5ts fill$ ) ,basalt or o!r ,lava-=m ,rock--,v5ts fill$ ) ,agglom]ate ,x is "o ( ! mo/ int]e/+ po9ts 9 ! ,t]ti>y volcanic hi/ory t1 9 spite ( ! enorm\s geological revolutions t h pass$ s9ce !y became ext9ct1 ! sites ( _m scatt]$ v5ts c /ill be recogniz$4 ,a f> great] numb] mu/ lie buri$ "u ! basalts1 & ( o!rs ! positions are conceal$ by ! sea1 :i* n[ cov]s s l>ge an area ( ! old lava-fields4 ,nev]!less1 p>tly )9 ! area ( ! plateaux1 b /ill m on ! surr\nd+ tracts f :i* ! basalts h be5 remov$ by d5udation1 ! traces ( unmi/akable v5ts ( dis*>ge may be recogniz$ amid ! g5]al wreck4 ,9 ,brita9 & ! ,f>oe ,isles1 x is *iefly along ! coa/-l9e t ! process ( d5udation has reveal$ ! volcanic v5ts ( ,t]ti>y "t4 ,! int]ior ( ! c\ntry is (t5 load$ ) peat1 cov]$ ) h]bage1 or /rewn ) glacial detritus3 & ev5 :]e indications ( ! v5ts are to be detect$1 x is n always possible to asc]ta9 _! true limits & connections4 ,b :]e ! /ructure ( ! plateaux has be5 laid b>e along ranges ( rocky precipice1 ! v5ts h sometimes be5 s admirably dissect$ by ! sea t e feature ( _! arrangem5ts c be satisfactorily det]m9$4 ,z ! actual physical connexion ( ^! volcanic orifices ) ! plateaux has be5 9 mo/ cases remov$ by d5udation1 we c usually only by inf]5ce place !m 9 :at 0 probably _! true relation to ! plateau-eruptions4 ,^? :i* project f ! surface ( ! plateaux mu/1 ( c\rse1 be y\ng] ?an ! basalts ?r\gh :i* !y rise2 h[ mu* y\ng] we _c tell4 ,!y may possibly be lat] ?an any ( ! plateau-%eets2 !y may ev5 belong to a subsequ5t & wan+ condition ( volcanic action4 ,on ! o!r h&1 ! v5ts :i* c n[ be trac$ outside ( ! pres5t limits ( ! edges ( ! plateaux may1 l ^? j m5tion$1 be y\ng] ?an ! basalt-%eets1 or1 on ! contr>y1 !y may be records ( a p]iod ( eruptivity ant]ior to ! emission ( any ( ! rocks ( ! plateaux1 & may h be5 deeply buri$ "u a mass ( basalt-b$s subsequ5tly remov$4 ,positive demon/ration is1 f ! nature ( ! case1 impossible 9 ^! in/ances4 ,b examples w be cit$ f ! ,we/]n ,isles & f ,f>oe1 :]e ! v5ts c be prov$ to belong to ! "t ( ! plateau-eruptions1 = !y are se5 to h brok5 ?r\gh "s ( ! basalt-%eets & to h be5 buri$ "u o!rs4 ,) ?is cle> evid5ce ( relation%ip 9 "s cases1 !re ne$ be little hesitation 9 believ+ t 9 o!r in/ances :]e no su* positive connexion c be f\nd1 b :]e ! v5ts are obvi\sly su* z ! g5]al /ructure ( ! plateaux w\ld h l$ u to expect1 !y may be confid5tly reg>d$ z "p ( ! ph5om5a ( ! plateau-eruptions4 ,sometimes ! v5ts c be l9k$ ) l9es ( fissures or dykes4 ,?is is especially ! case :]e !y are small 9 size4 ,m usually1 h[ev]1 no su* relation c be demon/rat$4 ,x w be rememb]$ t among ! mod]n ,icel&ic eruptions1 "s eruptive v5ts1 l ! lat] c9d]-cones ( ,laki1 are rang$ 9 a l9e> direction along ! great fissure1 :ile o!rs1 ( an old] s]ies 9 ! same di/rict1 almo/ engulph$ amid/ ! m rec5t lavas1 are clu/]$ irregul>ly 9 gr\ps4 ,a simil> div]sity ( arrangem5t has be5 obs]v$ among ! volcanic cones ( ! ,velay 9 ,c5tral ,france4 ,consid]+ z a :ole ! volcanic necks or eruptive v5ts :i* rise f ! old] rocks ar\nd ! ,t]ti>y basalt-plateaux1 & sometimes ev5 f ! surface ( ^! plateaux !mselves1 we may conv5i5tly foll[ ! same classification z 0 adopt$ 9 deal+ ) ^? ( ,palozoic age1 &1 accord+ to ! nature ( ! mat]ial t n[ fills !m1 arrange !m 9 two s]ies3 7#a7 ,^? occupi$ by "s =m ( cry/all9e eruptive rock1 & 7#b7 ^? fill$ ) volcanic agglom]ate4 i4 ,,v5ts ,,fill$ ,,) ,,dol]ite1 ,,basalt1 ,,etc4 ,^!1 z ! composition ( ! plateaux w\ld lead u to anticipate1 are num]\s4 ,!y p]haps atta9 _! mo/ conspicu\s developm5t 9 ,antrim1 ei!r on ! tablel& or among ! und]ly+ rocks r\nd its edges4 ,! f9e/ example 9 t di/rict is und\bt$ly furni%$ by ! l(ty em95ce call$ ,slemi%1 :i* rises above ! surr\nd+ basalt-t]race1 to a height ( #adcg feet above ! sea 7,fig4 #bid74 ,x is elliptical 9 gr\nd-plan1 measur+ "s #djjj feet 9 l5g? by #ajjj 9 bread?4 ,se5 f ! nor?1 x appe>s z a ne>ly p]fect cone4 ,! mat]ial ( :i* x consi/s is a co>sely cry/all9e oliv9e-dol]ite1 pres5t+ "u ! microscope a ne>ly holocry/all9e aggregate1 9 :i* ! la?-%ap$ felsp>s p5etrate ! augite1 ) abundant fre% oliv9e1 & w$ge-%ap$ pat*es ( int]/itial matt]4 ,! rock is massive & amorph\s1 except t x is divid$ by p>allel jo9ts into l>ge quadrangul> blocks l a granitic rock1 & :olly diff]5t f ! "* ( ! surr\nd+ basalts4 ,! latt]1 :i* possess ! ord9>y *>act]s ( ! rocks ( ! plateaux1 c be foll[$ to )9 #hj y>ds ( ?is neck1 :i* rises /eeply f !m1 b _! actual junction ) x is conceal$ "u ! dep? ( talus4 ,illu/ration3 ,fig4 #bid4--,slemi%1 a ,volcanic ,neck or ,v5t on ! ,antrim ,plateau1 se5 f ! nor?4 ,illu/ration3 ,fig4 #bie4--,section ( ,volcanic ,v5t at ,c>nmony ,hill 7,e4 ,hull74 ,t1 ,l[] basalt2 ,c1 ,cretace\s /rata2 ,l1 ,l[] ,lias2 ,m1 ,triassic m>ls2 ,v1 ,v5t4 ,at ! ne>e/ po9t to :i* ! two rocks are traceable1 ! basalts appe> some:at indurat$1 break ) a peculi> spl9t]y fracture1 & wea!r ) a :ite cru/4 ,^! *>act]s are /ill bett] %[n on abundant fragm5ts :i* may be pick$ up among ! debris fur!r up ! slope4 ,!re c be no d\bt1 ,i ?9k1 t a r+ ( fl9ty basalt1 diff]+ consid]ably 9 texture f ! usual aspect ( t rock 9 ! di/rict1 surr\nds ! neck4 ,! mean+ ( ?is r+ w be m cle>ly se5 f ! description ( ano!r example 9 ,mull4 ,ab\t f\r miles to ! nor?-ea/ ( ,slemi%1 a small] & less conspicu\s neck rises out ( ! plateau-basalts4 ,! rock ( :i* x consi/s is less co>sely cry/all9e ?an t ( ,slemi%1 b its relations to ! surr\nd+ volcanic rocks are obvi\sly ! same4 ,on ! we/ side ( ,belfa/ ,l\gh a boss ( simil> rock1 ab\t #abjj feet 9 diamet]1 rises at ! v edge ( ! basalt esc>pm5t into ! em95ce kn[n z ,c>nmony ,hill 7,fig4 #bie74 ,on its nor!rn side x pres5ts along its wall a mass ( int]pos$ volcanic agglom]ate4#bie ,on visit+ ) ,mr4 ,m',h5ry ! qu>ry op5$ on ! ea/]n face ( ?is v5t1 ,i 0 mu* /ruck ) ! rem>kable cellul> /ructure ( "s p>ts ( ! dol]ite4 ,_m ( ! vesicles are l9$ ) a ?9 pellicle ( black glass1 & ! same sub/ance occurs 9 m9ute pat*es 9 ! body ( ! rock4 ,a ?9 slice exhibit+ ?is /ructure 0 f\nd by ,mr4 ,watts to possess ! foll[+ *>act]s3--,! rock is an ophitic dol]ite consi/+ ( plagioclase1 augite1 & iron ores1 )\t oliv9e1 enclos+ "o or two pat*es ( f9] basalt4 ,! vesicles 9 ! latt]1 & c]ta9 angul> spaces betwe5 ! cry/als ( ! =m]1 h be5 :olly or p>tially fill$ ) br[n glass1 ! out] "p ( :i* has be5 conv]t$ into radiat+ cry/als ( a br[n m9]al4 ,! occurr5ce ( pat*es ( glass :i* seem to h be5 squeez$ into vesicles or cracks 9 ! body ( a dol]ite or &esite has be5 notic$ 9 "s ( ! ,t]ti>y dykes4 ,b 9 ! pres5t case ! glass occurs z a m]e coat+ on ! walls ( ! l>g] sph]oidal vesicles1 ! int]ior ( :i* g5]ally rema9s empty4 ,footnote #bie3 ,?is neck 0 recognis$ by ,du ,noy] 9 #ahfh z "o ( ! great pipes or fe$]s ( ! basaltic fl[s4 ,see ,pr(4 ,hull1 ,explanation ( ,%eets #ba1 #bh & #bi1 ,geol4 ,survey ( ,irel& 7#ahgf71 p4 #cj4 ,( ! o!r dol]itic necks scatt]$ ov] ! surface ( ! ,antrim plateau1 ,i w ref] to only "o :i* occurs on ! hillslopes betwe5 ,gl5>m & ,l>ne4 ,x =ms a prom95ce kn[n z ! ,scawt ,hill1 & consi/s ( a boss ( basalt1 :i*1 9 ris+ ?r\gh a v5t 9 ! plateau-%eets1 has c>ri$ up ) x & conv]t$ into m>ble a l>ge mass ( *alk :i* is n[ expos$ along its ea/]n wall 7,fig4 #bif74 ,illu/ration3 ,fig4 #bif4--,section ( ! ea/ side ( ,scawt ,hill1 ne> ,gl5>m4 a1 b$d$ basalt2 b1 mass ( *alk2 c1 basalt neck4 ,illu/ration3 ,fig4 #big4--,section ( ,neck ( ,basalt1 ,b5doo1 ,ball9toy4 a a1 ,*alk2 b1 neck4 ,z examples ( simil> necks :i* h be5 expos$ by d5udation outside ! pres5t limits ( ! same plateau1 ,i may allude to ^? :i* rise ?r\gh ! ,cretace\s & o!r ,second>y /rata on ! nor!rn coa/ ne> ,ball9toy4 ,"o ( ! mo/ /rik+ ( ^! may be se5 at ,b5doo1 :]e a plug ( basalt1 measur+ ab\t #adjj feet 9 "o diamet] & #hjj feet 9 ano!r1 rises ?r\gh ! ,*alk1 & alt]s x ar\nd ! l9e ( contact 7,fig4 #big74 ,ano!r rem>kably picturesque example is to be se5 ne> ,cu%5dall1 :]e a prom95t dol]itic cone rises out ( ! plat=m ( ,old ,r$ ,s&/one1 "s di/ance to ! nor? ( ! pres5t edge ( ! volcanic esc>pm5t 7,fig4 #bih74 ,illu/ration3 ,fig4 #bih4--,volcanic ,neck ( ,dol]ite ne> ,cu%5dall4 ,! great] co>s5ess ( gra9 ( ! mat]ial fill+ ^! pipes1 comp>$ ) t ( ! %eets 9 ! t]races1 is only :at ! v diff]5t conditions ( cool+ & consolidation w\ld lead u to expect4 ,!re is no ess5tial diff]5ce ( composition betwe5 ! two rocks4 ,:]e ! erupt$ mat]ial has be5 p\r$ out at ! surface1 x has assum$ a f9ely cry/all9e texture1 :ile1 :]e x has sl[ly solidifi$ )9 a volcanic pipe at "s dep? b5ea? ! surface1 & :]e consequ5tly its compon5t cry/als h _h m "t = developm5t1 ! result+ /ructure is mu* m l>gely cry/all9e1 ) a m or less complete developm5t ( ! ophitic /ructure4 ,illu/ration3 ,fig4 #bii4--,section ( ,volcanic ,neck at ',s ,airde ,be9ne1 ne> ,tob]mory1 ,mull4 a a1 b$d$ basalts2 b b1 b$d$ basalts alt]$ along ! side ( v5t2 c c1 dol]ite4 ,9 ! isl& ( ,mull1 ano!r in/ance ( ! same k9d ( v5t has be5 obs]v$ & describ$ by ,pr(essor ,judd4#bif ,x rises 9 ! conspicu\s hill1 ',s ,airde ,be9ne 7,s>ta ,be9n71 ab\t two miles s\?-we/ f ,tob]mory1 & consi/s ( a co>sely cry/all9e dol]ite1 :i* becomes f9] 9 gra9 t[>ds ! out] m>g9 7,fig4 #bii74 ,no b$d+1 or /ructure ( any k9d beyond jo9t+1 is p]ceptible 9 x4 ,exam9$ 9 ?9 sections "u ! microscope1 ?is rock is f\nd to be ano!r typical ophitic dol]ite1 consi/+ ( la?-%ap$ felsp>s emb$d$ 9 augite1 ) "h & !re w$ge-%ap$ portions ( int]/itial matt] & gra9s ( oliv9e4 ,dr4 ,hat* f\nd ! felsp>s to conta9 sph]ical inclusions ( devitrifi$ glass1 fill$ ) black granules & tri*ites1 & he obs]v$ t1 "u a high p[]1 ! int]/itial matt] is se5 to consi/ ma9ly ( a gre5i%-br[n isotropic sub/ance1 9 :i* are inclos$ small cry/als ( augite1 skeleton-=ms & microlites ( felsp>1 sometimes 9 /ellate aggregates1 z well z club-%ap$1 cruci=m1 arr[-head$ & (t5 cre/$ microlites ( magnetite4 ,footnote #bif3 ,qu>t4 ,j\r4 ,geol4 ,soc41 xxx4 7#ahgd71 p4 #bfd4 ,illu/ration3 ,fig4 #cjj4--;,int]ior ( ! ,volcanic ,neck ( ',s ,airde ,be9ne1 ne> ,tob]mory1 ,mull4 ,t[]+ prom95tly above ! flat basalt %eets1 ?is neck has an oval =m1 measur+ ab\t half a mile 9 l5g? by a qu>t] ( a mile 9 bread?4 ,its c5tral portion1 h[ev]1 in/ead ( ris+ into a rugg$ hill-top1 z is usually ! case1 s9ks into a deep holl[1 :i* is fill$ ) wat]1 & rem9ds "o ( a true crat]-lake 7,figs4 #bii1 #cjj74 ,! middle ( ! neck is ?us conceal$ f view1 & we c only exam9e ! h>d prom95t r+ ( dol]ite t surr\nds ! t>n4 ,! mat]ial occupy+ ! holl[ may be s(t] ?an t ( ! r+1 & may h be5 scoop$ out by d5udation4 ,:at we n[ see may n be ! orig9al surface1 b may h be5 expos$ aft] ! removal ( possibly hundr$s ( feet ( ov]ly+ mat]ial4 ,on ! o!r h&1 x is conceivable t ! holl[ is really a crat]-lake :i* 0 fill$ up ) detritus & may h be5 ov]spread ) basalt1 s9ce remov$4 ,x may be sugge/ively comp>$ ) ! crat]-holl[s reveal$ by d5udation on ! cliffs ( ,/rom & ,portree ,h>b\r1 :i* w be describ$ 9 a lat] "p ( ?is *apt]4 ,possibly "s m easily removable agglom]ate1 repres5t+ an eruption lat] ?an t ( ! dol]ite1 may occupy ! c5tre ( ! volcanic pipe4 ,"o ( ! mo/ int]e/+ features ( ?is v5t is to be f\nd 9 its relation to ! surr\nd+ basalts4 ,! m>g9al p>ts ( ! rock along ! l9e ( contact are mu* f9] 9 gra9 ?an ! re/1 & h obvi\sly cool$ m rapidly4 ,! contra/ betwe5 !m & ! ord9>y dol]ite ne>] ! c5tre1 h[ev]1 _c be prop]ly und]/ood1 except 9 ?9 sections "u ! microscope4 ,dr4 ,hat*1 to :om ,i submitt$ my specim5s1 obs]v$ t1 9 place ( ! /ructure above describ$1 ! m>g9al p>ts %[ an abs5ce ( ! ophitic gr\p+ except 9 small isolat$ pat*es4 ,in/ead ( occurr+ 9 l>ge gra9s or plates envelop+ ! felsp>s1 ! augite is f\nd 9 num]\s small r\ndi% gra9s1 toge!r ) gra9s ( magnetite1 9 equal abundance & ( simil> size4 ,! felsp>s are speckl$ ov] ) opaque p>ticles2 oliv9e has n be5 detect$4 ,= miles ar\nd ! v5t1 ! plateau-rocks are ( ! usual type--black1 compact1 sometimes amygdaloidal1 alt]nat+ ) m co>sely cry/all9e decompos+ b&s1 ! sep>ation betwe5 diff]5t %eets be+ (t5 m>k$ by ! ord9>y r$ f]rug9\s p>t+s4 ,b ar\nd ! m>g9 ( ! neck1 !y h und]gone a rem>kable metamorphism4 ,! portions ( !m :i* adh]e to ! out] wall ( ! neck h lo/ _! di/9ct b$d+1 & h be51 z x 71 weld$ toge!r into an indurat$ compact1 black to dull-grey rock1 s %att]y & jo9t$ t fre% h&-specim5s1 ?ree or f\r in*es 9 l5g?1 are n easily obta9able4 ,especially m>k$ is "o set ( jo9ts :i*1 runn+ approximately p>allel1 cause ! rock to split into plates or slabs4 ,^! jo9ts are sometimes curv$4 ,yet1 9 spite ( ! alt]ation f its normal "*1 ! basalt reta9s 9 places "s ( its m usual ext]nal features1 su*1 = in/ance1 z its amygdaloidal /ructure1 ! amygdales consi/+ ( calcite1 f9ely acicul> mesotype1 & o!r m9]als4 ,exam9$ "u ! microscope1 ?is alt]$ basalt pres5ts a confus$ aggregate ( col\rless microlites 7felsp>87 & innum]able m9ute granules ( magnetite1 ^! two con/itu5ts be+ v unequally di/ribut$4 ,sometimes ! col\rless portions prepond]ate1 9 o!r places ! opaque granules are heap$ toge!r 9 black pat*es1 :i* may possibly m>k ! position ( fus$ augites4#big ,footnote #big3 ,notes by ,dr4 ,hat*4 ,9 ! zone ( contact-metamorphism ar\nd "s ( ! volcanic pipes 9 ! plateaux1 we see *anges analog\s to1 b less develop$ ?an1 ^? :i* h be5 sup]9duc$ on s l>ge a scale r\nd ! great eruptive bosses ( gabbro1 granophyre1 etc41 t h brok5 up ! t]rac$ basalts along ! we/ coa/ ( ,scotl&4 ,i %all accord+ly return to ?is subject 9 connection ) ph5om5a pres5t$ by ^! y\ng] rocks 7p4 #chf74 ii4 ,,v5ts ,,fill$ ,,) ,,agglom]ate ,:ile ! necks ( dol]ite or basalt _c always be satisfactorily discrim9at$ f bosses :i* may nev] h e/abli%$ a connection ) ! surface1 !re is no room = any d\bt 9 ?is respect 9 ! case ( ^? fill$ ) fragm5t>y mat]ials4 ,z has be5 already po9t$ out1 ! occurr5ce ( true volcanic agglom]ate may be accept$ z evid5ce ( ! exi/5ce ( an eruptive v5t communicat+ ) ! surface ( ! e>?4 ,! agglom]ate 9 ! v5ts associat$ ) ! basalt-plateaux1 l t ( ! ,palozoic v5ts1 is g5]ally exce$+ly co>se1 & )\t any trace ( /ructure4 ,blocks ( all sizes up to masses "s y>ds 9 l5g?1 & ( ! mo/ div]sifi$ mat]ials1 bo? volcanic & non-volcanic1 are disp]s$ confus$ly ?r\gh a granul> pa/e ( simil> miscellane\s composition4 ,illu/ration3 ,fig4 #cja4--;,diagram to %[ ! probable relation ( ! ,neck at ,c>rick-a-raide1 ,antrim1 to an adjac5t gr\p ( tuffs4 a a1 ,*alk2 b b1 l[] gr\p ( b$d$ basalts2 c1 v5t ( ,c>rick-a-raide1 fill$ ) co>se volcanic agglom]ate2 d d1 b$d$ tuffs2 e e1 l>ge ve9s ( basalt trav]s+ ! agglom]ate2 f f1 zone ( tuffs & pisolitic iron ore2 g g1 upp] gr\p ( b$d$ basalts4 ,an in/ructive example ( ! g5]al *>act]i/ics ( agglom]ate-v5ts1 & ( ! relation ( ^! v5ts to ! surr\nd+ tuffs & basalts1 is to be f\nd at ! isl& ( ,c>rick-a-raide1 on ! nor? coa/ ( ,antrim1 & on ! opposite ma9l&4 ,! visible mass ( ?is neck is ab\t #ajjj feet 9 diamet]1 b ! b\nd>ies1 except on ! l& side1 are conceal$ by ! sea4 ,! mat]ial fill+ up ! v5t is a co>se agglom]ate1 9 :i* blocks & bombs ( basalt1 ) pieces ( *alk & fl9t1 are /uck at all angles 9 a dull dirty-gre5 granul> tuff4 ,"s l>ge & small intrusions ( basalt rise ?r\gh x4 ,ow+ p>tly to ^! intrusions1 & p>tly to ! grass-cov]$ slope t sep>ates x f ! l9e ( cliff1 ! actual contact ( ?is neck ) ! volcanic b$s ( ! esc>pm5t _c be se54 ,i h no d\bt1 h[ev]1 t ! tuff1 :i* has already be5 ref]r$ to z s conspicu\s a memb] ( ! s]ies "h1 0 dis*>g$ f ?is v5t4#bih ,! mat]ials are z usual co>s] 9 ! pipe ?an beyond x1 b ! f9] portion or matrix ( ! agglom]ate is simil> to _m b&s ( ! tuff4 ,! /ructure ( ! locality may be diagrammatically repres5t$ z 9 ,fig4 #cja4 ,! b$d$ tuff is ?icke/ 9 ! neighb\rhood ( ! v5t1 & gradually dies away on ei!r side ( x4 ,footnote #bih3 ,see ,explanation ( ,%eets #g & #h1 ,geol4 ,survey ( ,irel& 7#ahhh71 p4 #ca4 ,b ano!r important inf]5ce may be drawn f ?is locality4 ,i h already po9t$ out t ! l[] basalts "h rea* _! m9imum ?ickness4 ,_! basem5t b$s ?9 away t[>ds ! v5t z m>k$ly z ! tuff ?ick5s4 ,obvi\sly !y _c h proce$$ f t po9t ( eruption4 ,yet1 t !y _h begun to be p\r$ out be=e ! dis*>ge ( ! tuff is %[n by _! und]ly+ z well z ov]ly+ t rock1 ?\gh we/w>d1 ow+ to ! ?9n+ away ( ! und]mo/ basalts1 ! tuff comes to lie directly on ! ,*alk4 ,h5ce1 we may legitimately inf] t 9 ?is neighb\rhood "o or m o!r v5ts suppli$ ! %eets ( ! l[] basalts4 ,9 ! isl& ( ,mull a numb] ( deta*$ bosses or pat*es ( agglom]ate mu* obscur$ by invasions ( granophyre probably m>k ! sites ( volcanic v5ts4 ,!y w be m p>ticul>ly notic$ 9 ,*apt] xlvii4 ,"o ( _! mo/ int]e/+ features is ! l>ge numb] ( fragm5ts ( felsitic or rhyolitic rocks :i* !y conta94 ,9 ! promontory ( ,ardnamur*an1 :]e ! basalt-plateau has be5 invad$ & displac$ by lat] intrusions ( cry/all9e rocks1 & has likewise be5 r$uc$ to su* a fragm5t>y condition by d5udation1 "s int]e/+ examples ( agglom]ate necks h be5 laid b>e4 ,"o ( ! l>ge/ ( ^! occurs on ! nor? %ore at ,faskadale4 ,cut op5 by ! sea = m ?an a qu>t] ( a mile1 ?is neck is se5 to be fill$ ) a co>se agglom]ate1 compos$ ma9ly ( basalt-blocks & debris1 b cr[d$ also ) angul> & subangul> pieces ( diff]5t close-gra9$ &esitic1 felsitic & porphyritic rocks belong+ to ! acid s]ies to be aft]w>ds describ$4#bii ,"s ( ^! /ones exhibit a v p]fect fl[-/ructure1 & closely resemble c]ta9 f9e-gra9$1 fl9ty1 intrusive rocks 9 ,mull1 to :i* allusion w subsequ5tly be made4 ,! matrix ( ! agglom]ate is ( ! usual dull dirty-gre5 col\r1 b is s int5sely indurat$ t on a fre% fracture x c h>dly be di/+ui%$ f "s ( ! cry/all9e rocks ( ! locality4 ,! neck is pi]c$ 9 all directions ) dykes & ve9s ( basalt1 dol]ite1 &esite1 gabbro1 & felsitic rocks4 ,simil> intrusions cont9ue & increase 9 numb]s f>!r we/ until ! cliffs become a labyr9? ( dykes & ve9s runn+ ?r\gh a mass ( rocks :i* appe>s to consi/ ma9ly ( dull dol]ites & f9e gabbros4 ,?\gh ! relations ( ?is v5t to ! plateau-basalts are n q pla91 ! agglom]ate seem$ to me to rise out ( ^! rocks4 ,at lea/ ! basalts ext5d f ,a*at5y to ,faskadale1 b1 z !y are foll[$ we/w>ds1 !y are m & m invad$ by eruptive %eets1 & assume ! indurat$ "* to :i* ,i h already ref]r$4 ,footnote #bii3 ,"o ( ^! felsites :5 view$ "u a high magnify+ p[] is se5 to pres5t an abundant developm5t ( exce$+ly m9ute micropegmatite arrang$ 9 pat*es & /reaks p>allel ) ! l9es ( fl[-/ructure 9 ! g5]al cryptocry/all9e gr\ndmass4 ,! close relation%ip betwe5 ! felsites1 qu>tz-porphyries1 & granophyres w be aft]w>ds po9t$ out 9 ! description ( ! acid rocks4 ,x is rem>kable t1 ?\gh ^! rocks occur abundantly 9 fragm5ts 9 ! volcanic necks & agglom]ates ( ! plateaux1 n a s+le in/ance has be5 obs]v$ ( _! int]calation z contemporane\s %eets among ! basic lavas4 ,! analog\s case ( ! int]/ratification ( felsitic tuffs among basic lavas 9 ! volcanic s]ies ( ! ,old ,r$ ,s&/one ( ,c5tral ,scotl& has be5 describ$ 7vol4 i4 p4 #bgi74 ,x is int]e/+ to note t lip>itic pumice & dykes h be5 erupt$ by "s ( ! basaltic crat]s ( ,icel&1 = example at ,askja1 rfajkull & ,snaefellsjkull4 7,mr4 ,?orodds51 ,dansk4 ,geograf4 ,tidsskrift1 vol4 xiii4 #g? & #h? p>ts47 ,on ! s\? side ( ! p59sula ( ,ardnamur*an1 ano!r agglom]ate1 notic$ by ,pr(essor ,judd1#cjj rises into ! bold headl& ( ,maclean's ,nose1 at ! m\? ( ,lo* ,sun>t1 & af=ds bett] evid5ce ( its relation to ! b$d$ basalts4 ,x measures ab\t #ajjj y>ds 9 l5g? by #cjj 9 bread?1 & its summit rises m t #ijj feet above ! sea1 :i* wa%es ! base ( its s\!rn front4 ,x is fill$ ) an agglom]ate ev5 co>s] ?an t on ! nor!rn coa/4 ,! blocks are ( all sizes1 up to eight or t5 feet 9 diamet]4 ,by f> ! l>ge/ proportion ( !m consi/s ( v>ieties ( basalt & &esite1 slaggy & vesicul> /ructures be+ especially conspicu\s4 ,!re are also l>ge blocks ( diff]5t &esitic porphyries & felsitic rocks l ^? j ref]r$ to1 a porphyry ) felsp> cry/als two in*es long be+ p>ticul>ly abundant4 ,all ! /ones are m or less r\nd$1 & are wrapp$ up 9 a dull-gre5 compact matrix ( basalt-debris4 ,!re is no /ratification or /ructure ( any k9d 9 ! mass4 ,num]\s dykes or ve9s ( basalt1 ( &esite1 & ( a porphyry1 resembl+ t ( ,craignure1 9 ,mull1 trav]se ! agglom]ate4 ,"s ( ! n>r[ basalt-dykes cut ?r\gh ! o!rs4 ,footnote #cjj3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxx4 7#ahgd71 p4 #bfa4 ,pr(essor ,judd has subsequ5tly 7op4 cit4 xlvi4 #ahij1 pp4 #cgd et seq47 giv5 a map1 section & description ( :at he believes to be ! /ructure ( ?is gr\nd1 ) num]\s details z to ! petrography ( ! rocks4 ,! geological /ructure ( ?is area is m fully ref]r$ to on pp4 #cah et seq4 ,illu/ration3 ,fig4 #cjb4--,section ( agglom]ate ,neck at ,maclean's ,nose1 ,ardnamur*an4 a a1 qu>tzites & s*i/s2 b1 b$d$ basalts ly+ p>tly on ! s*i/s & p>tly on pat*es ( ,jurassic s&/ones t occupy holl[s ( ! old] cry/all9e rocks2 c1 agglom]ate2 d d1 dykes & ve9s trav]s+ ! agglom]ate2 e1 dol]ite %eets ( ,b5 ,hiant4 ,! position ( ! v5t1 ) ref]5ce to ! surr\nd+ rocks1 w be und]/ood f ! accompany+ section 7,fig4 #cjb74 ,on ! ea/]n side1 ! agglom]ate c be se5 to abut aga9/ ! truncat$ ends ( ! flat b$s ( ! plateau-basalts1 :i* are ( ! usual b$d$ compact & amygdaloidal "*4 ,!re c be no d\bt1 !re=e1 t ! v5t has be5 op5$ ?r\gh ^! basalts4 ,b x w be obs]v$ t ! latt] belong to ! l[] "p ( ! volcanic s]ies4 ,^! l[e/ %eets are expos$ on ! slope1 re/+ ^u yell[i% & spott$ grey s&/one1 ) seams ( jet & a r$di% breccia1 :i*1 ly+ 9 holl[s ( ! qu>tzites1 qu>tz-s*i/s1 & mica-s*i/s1 =m no d\bt ! local base ( ! ,jurassic rocks ( ! di/rict4 ,h5ce1 ! v5t1 ?\gh y\ng] ?an ! old] %eets ( ! plateau1 may q well be contemporane\s ) "s ( ! lat] %eets4#cja ,footnote #cja3 ,x may "h be rem>k$ t !re is evid5ce ( great diff]5ces 9 ! level ( ! base ( ! ,jurassic s]ies & ! bottom ( ! volcanic plateau 9 ?is di/rict4 ,on ! s\? & we/ sides ( ,b5 ,hiant ! ,jurassic conglom]ates may be se5 ly+ on ! edges ( ! cry/all9e s*i/s only a little above high-wat] m>k1 :ile on ! nor? side1 ! s*i/s1 ) _! ov]ly+ uncon=mable cake ( lime/ones1 rise sev]al hundr$ feet above sea-level4 ,! surface on :i* ! basalts 7 p\r$ out 0 probably v unev51 b !re may also h be5 "s consid]able displacem5ts ( ^! basalts ei!r be=e or dur+ ! injection ( ! dol]ite sills ( ,b5 ,hiant4 ,an int]e/+ feature at ?is locality is ! peculi> gr\p+ ( "s ( ! l>ge dykes 9 ! area ar\nd ! agglom]ate4 ,!y run 9 ! direction ( ! v5t1 & "o or o!r ( !m may repres5t ! fissure or fissures on :i* ! volcanic orifice 0 bl[n op5 to ! surface4 ,ano!r notable elem5t 9 ! geological /ructure ( ! gr\nd is ! va/ am\nt ( intrusive mat]ial1 bo? 9 dykes & %eets1 :i* has be5 erupt$4 ,! intrusive %eets ( ,b5 ,hiant =m ! mo/ prom95t em95ce 9 ?is "p ( ,ardnamur*an4 ,res]v+ !m = description 9 ! foll[+ ,*apt] 7p4 #cah71 ,i w only rem>k "h t !y p>tly ov]lie ! agglom]ate1 & are !re=e1 to "s ext5t at lea/1 y\ng] ?an ! v5t4 ,!y belong to t late /age 9 ! hi/ory ( ! basalt-plateaux :5 ! molt5 mat]ial1 no long] gett+ ready egress to ! surface1 =c$ its way among ! rocks ab\t ! base ( ! b$d$ basalts1 & m especially on ! sites ( old] v5ts1 :i* 7 d\btless weak places1 :]e x c\ld m easily f9d relief4 ,! l>ge neck n[ describ$ is only "o ( a gr\p scatt]$ ar\nd x 9 ! gr\nd to ! nor?4 ,two ( ^! may be se5 ris+ ?r\gh a deta*$ area ( ,jurassic lime/ones & %ales at ! nor!rn base ( ,b5 ,hiant4 ,a ?ird1 almo/ oblit]at$ by ! intrusive %eets1 may be trac$ at ! we/]n end ( t m\nta9 above ,coiremhuil9n4 ,two o!rs ris+ ?r\gh ! s*i/s on ei!r side ( ,be9n na h-,ur*ra*1 h be5 mu* invad$ by ! sills ( t em95ce 7,fig4 #cbf74 ,x is d\btless ow+ to ! ext5sive d5udation ( ! basalt-plateau1 & ! consequ5t uncov]+ ( ! rocks und]nea? x1 t ?is s]ies ( v5ts has be5 laid b>e4#cjb ,footnote #cjb3 ,pr(essor ,judd has unit$ ^! scatt]$ v5ts into a cont9u\s plat=m ( volcanic agglom]ates1 :i* he repres5ts z und]ly+ ! suppos$ lavas ( ,b5 ,hiant4 ,s9ce ! publication ( 8 map & description1 ,i h re-exam9$ ! gr\nd )\t be+ able to discov] any trace ( ?is plat=m4 ,all ! visible agglom]ates are sep>ate necks1 _! actual walls be+ sometimes expos$1 z 9 ! neck imm$iately nor? ( ! base ( ,b5 ,hiant1 :]e ! lime/one 9 contact is m>moris$1 ?\gh twelve y>ds ( x is an ord9>y dull blue rock4 ,by f> ! l>ge/ mass ( agglom]ate 9 any ( ! ,t]ti>y volcanic areas ( ,brita9 is t :i* occurs on ! nor? side ( ! ma9 valley ( ,/ra?1 9 ,skye4#cjc ,un=tunately1 x has be5 s s]i\sly invad$ by ! eruptive rocks ( ! ,r$ ,hills1 t its orig9al dim5sions & its relations to ! surr\nd+ rocks1 especially to ! b$d$ basalts1 are mu* obscur$ 7see ,fig4 #cdh74 ,x c be foll[$ cont9u\sly f ! l[] end ( ,lo* ,kil*ri/ along ! s\!rn slopes ( ,be9n ,de>g ,bheag r\nd to ! we/]n roots ( ,be9n ,de>g ,mhor--a di/ance ( m ?an two miles 9 a /raight l9e1 & f ,kilbride to ! flank ( ,be9n na ,cailli* above ,coire-*at-a*an--a direct di/ance ( two miles & a qu>t]4 ,a simil> rock1 possibly a portion ( ! same mass1 appe>s 9 ,creagan ,dubha1 on ! nor? side ( ! ,r$ ,hills4 ,if ! :ole ( ?is agglom]ate =ms "p ( "o orig9ally cont9u\s mass1 x mu/ h be5 upw>ds ( two miles 9 diamet]4 ,!re may1 h[ev]1 h be5 two or ?ree closely adjac5t v5ts4 ,! ,be9n na ,cailli* pat*1 = example1 appe>s to belong to a diff]5t area1 & t ( ,creagan ,dubha is also probably di/9ct4 ,b !re seems no reason to d\bt t ! mass :i* =ms ,cnoc nam ,fi!a*1 & all ! long declivity on ! s\!rn flank ( ,be9n ,de>g ,bheag1 occupies "p ( ! site ( a s+le volcano4 ,ow+ to ! abs5ce ( suffici5t sections1 x is h>dly possible to det]m9e h[ mu* ( ?is fragm5t>y mat]ial %\ld be assign$ to ! actual *imney4 ,! diamet] ( ! :ole mass is almo/ two miles4 ,b possibly a consid]able proportion ( ?is accumulation belongs to ! ext]nal cone :i* ga!r$ r\nd ! v5t1 s t ! eruptive pipe might ?us be ( mu* small] dim5sions ?an ! sup]ficial area ( ! agglom]ate4 ,! subsequ5t invasion ( s mu* granophyre1 n only t ( ! ,r$ ,hills1 b t ( num]\s small] intrusions1 has indurat$ ! agglom]ate & made ! inve/igation ( its /ructure some:at unsatisfactory4 ,footnote #cjc3 ,?is ext5sive mass 0 n sep>at$ f ! sy5ite ( ! ,r$ ,hills by ,maccullo*4 ,von ,oeynhaus5 & ,von ,de*5 notic$ x z a conglom]ate ) qu>tz pebbles1 b did n realise its volcanic nature 7,k>/5's ,ar*iv1 i4 p4 #ij74 ,9 my map ( ,/ra? 7,qu>t4 ,j\r4 ,geol4 ,soc4 xiv4 plate i47 ,i di/+ui%$ x f ! rock ( ! ,r$ ,hills1 b no "n = x appe>s 9 ! leg5d ( ! map1 nor is x ref]r$ to 9 ! text4 ,its "* z a true volcanic agglom]ate 0 recognis$ by ,pr(essor ,judd1 op4 cit4 p4 #bee4 ,see po/ea1 pp4 #chd et seq4 ,x might be suppos$ t ! m]e exi/5ce ( intrusive bosses & ve9s r furni%es an argum5t 9 fav\r ( consid]+ ! visible agglom]ate to belong to a deep]-seat$ "p ( ! erupt$ mat]ial ?an ! ext]nal cone4 ,b1 z w be aft]w>ds %[n1 !re is "s reason to reg>d ! pres5t conical or dome-%ap$ outl9es ( ! granophyre hills z n f> f _! orig9al =ms1 & to believe t1 l ! tra*ytic ,puys ( ,auv]gne1 !y 7 mu* m sup]ficial ?an plutonic eruptions4 ,a /udy ( ! c9d] cones ( ,c5tral ,france %[s t ev5 ^! sup]ficial accumulations h be5 invad$ n only by bosses b by dykes4#cjd ,footnote #cjd3 ,! exi/5ce ( a small dyke ( &esite on ! nor!rn rim ( ! well-kn[n crat] ( ! ,puy ,p>ion has already be5 notic$4 ,! agglom]ate ( ! great ,/ra? v5t is a co>se tumultu\s assemblage ( blocks & bombs1 imb$d$ 9 ! usual dull1 dirty-gre5 matrix4 ,among ! /ones1 grit & s&/one1 toge!r ) scoriace\s1 vesicul> & amygdaloidal basalts are specially abundant2 also pieces ( v>i\s qu>tz-porphyries & granophyres1 among :i* a black felsite l t ( ,mull may (t5 be recognis$4 ,9 "s places1 l>ge masses ( alt]$ lime/one & qu>tzite 7,cambrian7 are includ$2 9 o!rs1 pieces ( yell[ s&/one & d>k %ale 7,jurassic71 or ( ! b$d$ lavas4 ,"s ( ^! masses may be #ajj y>ds or m 9 l5g?4 ,occasionally a breccia1 ma9ly made up ( acid mat]ials--granophyre or granite1--has be5 notic$ by ,mr4 ,h>k] along ! nor? side ( ! ,r$ ,hills1 :i* he ?9ks may r be ( ! nature ( a cru%-breccia ?an a "p ( ! true agglom]ate4 ,! agglom]ate ( ?is di/rict is :olly )\t /ratification or /ructure ( any k9d4 ,on ! nor?-we/ side ( ,lo* ,kil*ri/1 inde$1 x wea!rs into l>ge tabul> =ms1 ! p>allel surfaces ( :i* dip to s\?-we/2 b ?is is probably due only to jo9t+4 ,"h & !re1 dykes ( basalt cut ! rock 9 a g5]al nor?-we/]ly direction1 b _! numb] is rem>kably small :5 comp>$ ) ! prodigi\s quantity ( !m 9 ! lime/one at ! bottom & opposite side ( ! valley1 "s ( :i* may possibly m>k ! fissure on :i* ! v5t 0 plac$4 ,m abundant & ext5sive are ! masses ( granophyre t rise p>ticul>ly along ! out] m>g9 ( ! agglom]ate ne> ,lo* ,kil*ri/4 ,^! may be connect$ ) ! great boss t =ms ! ,r$ ,hills1 ( :i* fur!r details w be giv5 9 ,*apt] xlvi4#cje ,footnote #cje3 ,! granophyre intrusions 9 ?is agglom]ate h be5 f\nd by ,mr4 ,h>k] to h tak5 up & dissolv$ a consid]able proportion ( fragm5ts ( gabbro1 ,*apt] xlvi4 p4 #cib4 ,! important "q ( ! relation ( ?is agglom]ate to ! plateau-basalts does n admit ( satisfactory treatm5t1 ow+ to de/ruction ( ! evid5ce by ! intrusion ( ! granophyre1 & likewise to enorm\s d5udation4 ,nev]!less1 "s traces /ill rema9 to indicate t ! basalts once /ret*$ ov] ! site ( ! v5t1 :i* probably rose ?r\gh !m4 ,look+ we/w>d f ! ,hanks ( ,be9n ,de>g ,bheag to ! o!r side ( ,lo* ,slap91 ! geologi/ sees ! bold basalt-esc>pm5t ( ,/ra?aird pres5t+ its truncat$ b$s to him at a di/ance ( only two miles4 ,t ^! lavas 7 once prolong$ ea/w>ds beyond _! pres5t limits is obvi\s1 & t !y /ret*$ at lea/ ov] ^! two int]v5+ miles c h>dly be d\bt$4 ,b we c /ill detect relics ( !m on ! flanks ( ,be9n ,de>g4 ,z we foll[ ! agglom]ate r\nd ! m>g9 ( ! granophyre t m\nts /eeply f x1 we lose x "h & !re "u b$s ( amygdaloidal basalt4 ,! rocks next ! great eruptive mass ( ! m\nta9 are s indurat$ & %att]$ t x is difficult to sep>ate !m f ea* o!r & det]m9e _! relative positions4 ,b1 s f> z ,i c\ld asc]ta91 ^! basalts are fragm5ts ( b$s t ov]lie ! agglom]ate 7,fig4 #cjc74 ,?is is n ! only place along ! flanks ( ! ,r$ ,hills :]e portions ( ! b$d$ basalts h surviv$4 ,o!r localities w be subsequ5tly allud$ to4 ,illu/ration3 ,fig4 #cjc4--;,diagram to %[ ! probable relations ( ! rocks on ! s\!rn flank ( ,be9n ,de>g ,bheag4 a1 agglom]ate2 b1 amygdaloidal & compact basalt-rocks2 c1 granophyre4 ,! ,/ra? v5t has be5 drill$ ?r\gh ! ,cambrian lime/one1 & z ! result ( protract$ d5udation x n[ t[]s /eeply #ejj or #fjj feet above t =mation on ! floor ( ! valley4 ,( ! mat]ial dis*>g$ f x ov] ! surr\nd+ c\ntry no c]ta9 trace n[ rema9s4 ,we may inf] f ! nature ( ! rock :i* fills x t t[>ds ! end1 if n f ! beg9n+ ( its activity1 its dis*>ges consi/$ ma9ly ( du/ & /ones4 ,a cone1 ( :i* ! rema9s are two miles 9 diamet]1 mu/ surely h s5t its fragm5t>y mat]ials f> & wide ov] ! surr\nd+ region4 ,b on ! b>e plat=m ( old] rocks to ! s\?1 beyond ! bottom ( ! agglom]ate declivities1 n a ve/ige ( ^! erupt$ mat]ials c n[ be f\nd4 ,we/w>d ! esc>pm5t ( ,/ra?aird rema9s to assure u t no ?ick %[]s ( a%es fell at ev5 s %ort a di/ance z two miles1 ei!r be=e or dur+ ! outp\r+ ( ! successive basalt %eets /ill rema9+ !re4 ,we may !re=e conclude ) "s confid5ce t "h1 z at ,ardnamur*an1 ! v5t is y\ng] ?an at lea/ ! old] p>ts ( ! basalt-plateau4 ,un=tunately ! uprise ( ! l>ge bosses ( granophyre t /ret* f ! ,r$ ,hills to ,lo* ,sliga*an has entirely de/roy$ ! v5t & its connections 9 t direction4 ,!re is no c]ta9 pro( t any molt5 rock ev] issu$ f ?is orifice1 unless we suppose ! fragm5t>y pat*es ( amygdaloid on ! s\!rn flank ( ,be9n ,de>g ,bheag to be portions ( fl[s t proce$$ f ?is c5tre ( eruption4 ,! basalt-plateau :i* /ill rema9s 9 ,/ra?aird no d\bt =m]ly ext5d$ ea/w>ds ov] ,/ra? & nor?w>ds across ! site ( ! ,r$ ,hills & ,cuill9s1 jo9+ on to ! cont9u\s tablel& nor? ( ,lo*s ,brittle & ,sliga*an4 ,h[ mu* ( ! plateau _h be5 built up "h be=e ! outbur/ ( ! v5t _c be asc]ta9$4 ,! agglom]ate may possibly1 ( c\rse1 belong to ! v late/ p]iod ( ! plateau-eruptions1 or ev5 to a /ill y\ng] phase ( ,t]ti>y volcanic hi/ory4 ,! impression1 h[ev]1 made on my m9d by a /udy ( ! evid5ce f ! ,we/]n & ,f>oe ,isles is t ! necks ( agglom]ate1 l ^? ( dol]ite & basalt1 really belong to diff]5t epo*s ( ! plateau p]iod itself2 & m>k "s ( ! v5ts f :i* ! mat]ials ( ! plateaux 7 successively emitt$4 ,! example ( ,c>rick-a-raide 7p4 #bgg7 is peculi>ly sugge/ive :5 we reg>d x 9 connexion ) ! great ,/ra? v5t4 ,already ! progress ( d5udation has remov$ at lea/ half ( ! lay] ( du/ & /ones :i*1 ?r[n out f t little orifice1 fell ov] ! b>e *alk-wolds & black basalt-fields ( ,antrim4 ,! neck t m>ks ! position ( ! volcanic funnel has be5 l>gely cut away by ! waves1 & is almo/ entirely isolat$ among !m4 ,! v5ts at ,canna1 ,portree & ! ,f>oe ,isles1 to be aft]w>ds describ$1 unque/ionably belong to ! eruptions ( ! plateau-p]iod1 = _! connection ) ! basalts c be cle>ly e/abli%$4 ,at ! ,/ra? v5t1 h[ev]1 ! m>* ( de/ruction has be5 great]4 ,! connexion betwe5 ?is v5t & ! mat]ials eject$ f x has be5 entirely remov$1 & we c only guess f ! size ( ! rema9+ neck :at may h be5 ! area cov]$ by ! dis*>ges f ?is l>ge/ ( all ! volcanic cones ( ! ,inn] ,hebrides4 ,o!r masses ( simil> agglom]ate are obs]vable 9 ! same region ( ,skye1 :]e !y n improbably m>k ! sites ( o!r v5ts4 ,un=tunately _! orig9al limits & relations to ! rocks ?r\gh :i* ! eruptive orifices 7 drill$ h be5 mu* obscur$ by ! uprise ( ! great masses ( gabbro & granophyre ( ! ,cuill9 ,hills4 ,sev]al ( ^! isolat$ intrusions occur 9 ! mid/ ( ! gabbro1 z 9 ,h>ta ,corry & on ! we/ side ( ! ,blav5 ridge4 ,ano!r mass is int]pos$ betwe5 ! gabbro & granophyre on ,druim an ,eidhne & at ! base ( ! lavas betwe5 ,druim an ,eidhne & ! ,camasun>y valley4 ,mr4 ,h>k] has f\nd a huge mass ( agglom]ate und]ly+ ! b$d$ basalts to ! nor? & we/ ( ,belig1 "o ( ! hills on ! we/ side ( ! l>ge valley t runs f ! head ( ,lo* ,slap9 to ,lo* ,aynort4 ,?is mass has its bottom conceal$ by ! granophyre :i* und]lies x2 b x rea*es a maximum ?ickness ( p]haps #ajjj feet1 rapidly ?9n+ out & disappe>+4 ,x g5]ally resembles ! ,/ra? agglom]ate1 b is di/+ui%$ by includ+ a l>ge proportion ( fragm5ts ( gabbro4 ,mr4 ,h>k] rem>ks t a /udy ( ^! agglom]ates po9ts to ! exi/5ce ( bo? gabbros & granophyres old] ?an ! volcanic s]ies1 & !re=e di/9ct f ! gabbros & granophyres n[ expos$ at ! surface4 ,x is a sugge/ive fact t s _m deta*$ masses ( agglom]ate %\ld occur ar\nd & )9 ! areas ( ! great eruptive bosses ( gabbro & granophyre4 ,!y seem to indicate ! =m] exi/5ce ( gr\ps ( volcanic v5ts 9 ^! tracts1 & may ?us acc\nt = ! uprise ( su* l>ge bodies ( intrusive mat]ial ?r\gh :at mu/ h be5 a weak5$ "p ( ! t]re/rial cru/4 ,fur!r nor? 9 ,skye a mu* small] b m p]fectly pres]v$ v5t has be5 laid op5 by d5udation on ! s\? side ( ,portree ,bay--a deep inlet :i* has be5 cut out ( ! plateau-basalts & _! und]ly+ plat=m ( ,jurassic s&/ones & %ales4 ,! great esc>pm5t ( ! basalts has1 at ! recess ( ,camas ,g>bh1 be5 tr5*$ by a small rivulet1 aid$ by ! pres5ce ( two dykes4 ,! gully ?us =m$ exposes a section ( a neck ( agglom]ate t und]lies ! basalts ( ! upp] half ( ! cliff4 ,?is neck is connect$ ) a ?ick deposit ( volcanic conglom]ate & tuff :i*1 ly+ betwe5 ! basalts1 ext5ds f ! neck to a consid]able di/ance on ei!r h&4 ,! g5]al relations ( ! rocks at ?is locality are repres5t$ 9 ,fig4 #cjd4 ,illu/ration3 ,fig4 #cjd4--,section ( ,volcanic ,v5t & connect$ lavas & tuffs1 ,scorr1 ,camas ,g>bh1 ,portree ,bay1 ,skye4 a1 ,rudely-b$d$ dull gre5 tuff2 b1 co>se agglom]ate2 c1 prismatic basalt2 d1 massive jo9t$ basalt2 e1 r$ b&$ decompos+ rock1 probably ( detrital orig92 f1 plateau-basalts1 prismatic & rudely column>2 g1 dyke ( dol]ite1 some:at vesicul>1 five to six feet broad2 h1 basalt dyke two to ?ree feet broad2 i1 dyke or sill ( simil> basalt to h1 & possibly connect$ ) x4 ,! agglom]ate 7b7 is q tumultu\s1 & "h & !re /rik+ly co>se4 ,"s ( its includ$ blocks measure five feet 9 l5g?4 ,^! fragm5ts repres5t mo/ ( ! v>ieties ( ! lavas ( ! di/rict4 ,l>ge slaggy masses are abundant among !m1 & sometimes exhibit ! annelide-l elongation ( ! vesicles :i* ,i h ref]r$ to z occasionally display$ by ! plateau-basalts4 ,m ?an #fj feet ( agglom]ate are visible 9 v]tical height f :]e its base is conceal$ by debris & vegetation to :]e its upp] surface passes "u a b&$ rock to be aft]w>ds describ$4 ,t ?is un/ratifi$ mass ( volcanic detritus m>ks ! site ( a v5t c h>dly be d\bt$1 al?\gh d5udation has n reveal$ ! actual walls ( ! *imney4 ,! /eep grassy slopes d n p]mit ! relations ( ! rocks to be ev]y:]e se51 b ! agglom]ate appe>s to pass lat]ally into f9]1 rudely-/ratifi$ mat]ial ( a simil> k9d1 :i* ext5ds t[>ds ea/ & we/ z a ?ick deposit betwe5 ! b$d$ basalts4 ,possibly d5udation has only advanc$ f> en\gh to lay b>e ! crat] & its surr\nd+ %eets ( fragm5t>y mat]ial1 :ile ! *imney lies /ill buri$ und]nea?4 ,to ! ea/ or left ( ! agglom]ate ! detritus becomes less co>se1 & %[s increas+ indications ( a b$d$ arrangem5t4 ,close to ! agglom]ate ! dip ( ! co>se tuff is t[>ds t rock at ab\t #aj4 ,a few y>ds fur!r ea/ a %eet ( v slaggy basalt is se5 to lie aga9/ ! tuff1 :i* x does n pi]ce4 ,! vesicles 9 ?is adh]+ cake ( lava h be5 pull$ out 9 ! direction ( ! slope till !y h become n>r[ tubes f\r or five in*es long & p>allel to ea* o!r4 ,"s p>ts ( ?is rock h a curv$ ropy surface1 l t ( well-kn[n ,vesuvian lavas1 sugge/ive ( ! molt5 rock hav+ fl[$ 9 successive ?9 visc\s %eets d[n ! slope1 :i* has a declivity ( ab\t #cj4 ,?is "p ( ! section may possibly pres]ve a fragm5t ( ! actual inn] slope ( ! crat] =m$ ( rudely-b$d$ tuffs4 ,cont9u+ /ill ea/w>d1 we f9d ! feebly /ratifi$ tuff 7a7 to be p]haps #bjj feet ?ick4 ,x =ms a grassy declivity t desc5ds f ! basalt-esc>pm5t above to ! grass-cov]$ plat=m :i* ov]lies a l[] gr\p ( basalts4 ,! visible portion ( ?is tuff pres5ts a ?or\ghly volcanic "*1 be+ made up ( ! usual dull dirty-gre5 granul> pa/e1 ?r\gh :i* are disp]s$ angul> & r\gh lumps ( slag & pieces ( m solid basalt1 v>y+ up to a foot or two feet 9 l5g?4 ,^! /ones are g5]ally dispos$ p>allel to ! indi/9ct b$d+1 b are sometimes plac$ on end1 z if !y _h assum$ t position on fall+ f an explosive %[]4 ,among ! small] /ones1 pieces ( a f9ely vesicul> basic pumice are frequ5t & are among ! mo/ /rik+ly volcanic products ( ! deposit4 ,f a *>act]i/ic sample ( ^! /ones1 a ?9 slice 0 prep>$ & plac$ 9 ,mr4 ,h>k]'s h&s4 ,! foll[+ are 8 obs]vations on x3--,a v compact d>k grey rock1 amygdaloidal on a m9ute scale4 ,! light] grey cru/ is probably due m]ely to wea!r+1 & ! specim5 seems to be a di/9ct fragm5t1 n a true bomb4 ,! slice %[s x to be ess5tially a br[n glass ) only occasional microscopic cry/als ( a basic plagioclase4 ,x has be5 highly vesicul>1 & ! vesicles are n[ fill$ by v>i\s second>y products1 includ+ a *loritic m9]al1 ne>ly col\rless & s+ly refract+ 9 ?9 section1 & a zeolite4 ,trac+ n[ ! tuff f ! we/ or "r side ( ! v5t1 we c foll[ x to a great] di/ance4 ,no abrupt l9e c be detect$ "h1 any m ?an on ! o!r side1 betwe5 ! agglom]ate & ! tuff4 ,! latt] rock ext5ds "u ! ov]ly+ plateau ( basalt1 at lea/ z f> we/ z ,portree ,lo*1 a di/ance ( fully a mile1 b rapidly dim9i%es 9 ?ickness 9 t direction4 ,traces ( :at is probably ! same tuff c be detect$ betwe5 ! basalts at ,a* na ,hannait1 m ?an ?ree miles to ! s\? 7,fig4 #cje74 ,x is ?us probable t f ! ,portree v5t fragm5t>y dis*>ges took place ov] an area ( sev]al squ>e miles4 ,above ! agglom]ate ( ?is v5t two lavas may be se5 to />t t[>ds opposite directions4 ,"o ( ^! 7c71 already ref]r$ to1 is a dull prismatic basalt ) a slaggy bottom1 its vesicles be+ pull$ out 9 ! direction ( ! g5]al b$d+ ( ! section4 ,x desc5ds by a twi/ or /ep1 & !n lies on ! incl9$ surface ( ! tuff :i* dips t[>ds ! agglom]ate & seems to pass into t rock4 ,fur!r ea/ ?is basalt increases 9 ?ickness & =ms ! l[e/ ( ! basalt-%eets ( ! cliff4 ,! lava t comm5ces on ! we/ side ( ! agglom]ate 7d7 is a massive jo9t$ basalt1 :i*1 ?\gh n se5 at ! v5t1 appe>s imm$iately to ! we/ ( x & rapidly swells out s z to become "o ( ! ?icke/ %eets ( ! locality4 ,x lies ^u ! rudely-b$d$ tuff1 & is cov]$ by ! o!r basalts ( ! cliff4 ,t ^! two basalts came out ( ?is v5t _c be affirm$4 ,if !y did s at diff]5t times1 _! emission mu/ h be5 foll[$ by ! explosion :i* cle>$ ! funnel & left ! c5tral mass ( agglom]ate !re4 ,b t "s k9d ( sauc]-%ap$ depression 0 /ill left above ! site ( ! v5t is indicat$ by ! curi\s elliptical mass ( rock 7e7 t lies imm$iately above ! agglom]ate1 f :i* x is %>ply m>k$ (f4 ,?is is "o ( ! mo/ puzzl+ rocks 9 ! di/rict1 probably 9 l>ge measure ow+ to its advanc$ /ate ( decay4 ,x is dull-r$ 9 col\r1 & decomposes into r\ghly p>allel lay]s1 s t at a %ort di/ance x looks l a b$d$ tuff1 or l "s ( ! crumbl+ v>ieties ( b&$ lavas4 ,i c\ld n obta9 specim5s fre% en\gh to put its nature & orig9 beyond dispute4 ,:atev] may h be5 its hi/ory1 ?is f]rug9\s rock re/s 9 a flat bas9-%ap$ holl[ directly above ! agglom]ate ( ! v5t4 ,! =m ( ?is depression corresponds fairly well ) :at we may suppose to h be5 ! f9al position & %ape ( ! crat] ( ! little volcano4 ,! rock t occupies ! b[l dies out t[>ds ! ea/ on ! face ( ! cliff1 & ! prismatic basalt 7c7 is !n imm$iately cov]$ by ! re/ ( ! basalt-%eets ( ! plateau 7f74 ,on ! we/ side its precise t]m9ation is conceal$ by grass4 ,b x mu/ rapidly dw9dle 9 t direction also1 = n _m y>ds away x is f\nd to h disappe>$1 & ! basalts 7d & f7 come toge!r4 ,?\gh ! decay$ /ate ( ?is rock does n w>rant any v confid5t op9ion reg>d+ its hi/ory1 ,i am incl9$ to look ^u x z a deposit ( mu* dis9tegrat$ volcanic detritus wa%$ into ! holl[ ( ! old crat] :5 x _h become fill$ ) wat]1 & _h pass$ into ! condition ( a ma>4 ,! peculi>ly oxidiz$ condition ( its mat]ials po9ts probably to long atmosph]ic exposure1 & an exam9ation ( ! surr\nd+ p>ts ( ! di/rict furni%es m or less di/9ct evid5ce t a consid]able lapse ( "t did actually int]v5e betwe5 ! cessation ( ! eruptions ( ! ,portree volcano & ! next great basalt-floods ( ?is "p ( ,skye4 ,t volcanic eruptions f o!r v5ts cont9u$ aft] ! ,portree v5t _h become ext9ct is prov$ by ! great %eets ( basalt 7f7 t ov]spread x1 & /ill bury a l>ge tract ( ! fragm5t>y mat]ial :i* x dis*>g$4 ,at a lat] "t a fissure t 0 op5$ across ! v5t1 all[$ ! uprise ( a basalt dyke 7g71 & subsequ5tly ano!r injection ( simil> mat]ial took place along ! same l9e ( weakness 7h74 ,be=e leav+ ?is int]e/+ locality we may briefly take note ( ! di/ribution ( ! a%es & /ones eject$ by ! volcano1 & ! evid5ce = ! relative l5g? ( ! int]val betwe5 ! outfl[ ( ! lavas bel[ & t ( ^? above ! tuff & volcanic conglom]ate4 ,^! deposits may be trac$ 9 cle> sections along ! base ( ! cliffs = a mile to ! we/ ( ! v5t4 ,!y ?9 away s rapidly 9 t direction t at a di/ance ( ?ree-qu>t]s ( a mile !y d n mu* exce$ fifty feet 9 ?ickness4 ,at ,camas ,bn !y consi/ ma9ly ( a f9e1 dull-gre51 granul>1 rudely-/ratifi$ basalt-tuff1 ?r\gh :i* occasional angul> pieces ( diff]5t lavas & r\gh slags are irregul>ly disp]s$4 ,^! /ones occur "h & !re 9 r[s1 sugge/ive ( m vigor\s dis*>ges1 ! lay]s betwe5 ! plat=ms ( co>s] detritus be+ occupi$ by f9e tuff4 ,"s ( ! eject$ blocks are imb$d$ on end--an indication ( ! =ce ) :i* !y 7 project$ s z to fall ne>ly a mile f ! crat]4 ,! upp] p>ts ( ! tuff pass upw>d into f9e yell[1 br[n1 & black clays a few feet 9 ?ickness1 ! d>k] lay]s be+ full ( c>bonace\s /reaks4 ,on ?is horizon ! coal ( ,portree 0 =m]ly m9$4 ,! work+s1 h[ev]1 h long be5 ab&on$1 &1 ow+ to ! fall ( l>ge blocks f ! basalt-cliff ov]head1 ! entrance to ! m9e is almo/ completely block$ up4 ,"o wood5 prop may /ill be se5 keep+ up ! ro( ( ! adit1 :i* is "h a slaggy basalt4 ,to ! ea/ & s\?-ea/ ( ! ,portree v5t1 ext5sive l&slips ( ! volcanic s]ies & ( ! und]ly+ ,jurassic =mations make x h>dly possible to trace ! cont9uation ( ! tuff-zone 9 t direction4 ,to ! s\?1 h[ev]1 at a di/ance ( r m ?an ?ree miles1 :at is probably ! same /ratigraphical horizon may be conv5i5tly exam9$ f ,a* na ,hannait = "s way to ! nor? ( ,tianavaig ,bay4 ,at ! =m] locality ! calc>e\s s&/ones ( ! ,inf]ior ,oolite are uncon=mably cov]$ by ! gr\p ( rocks repres5t$ 9 ,fig4 #cje4 ,at ! bottom ( ! volcanic s]ies lies a %eet ( nodul> dol]ite ) a slaggy upp] surface 7a74 ,wrapp+ r\nd ! projections & fill+ up ! depressions ( ?is lava comes a ?9 gr\p ( s$im5t>y /rata f an in* or two to eighte5 in*es or m 9 ?ickness 7b74 ,^! deposits consi/ ( h>d5$ %ale *>g$ ) mac]at$ fragm5ts ( l9e> leaves & o!r plant-rema9s1 includ+ & pass+ into /reaks ( coal1 :i* may be look$ ^u z probably occupy+ ! same horizon ) ! coal ( ,portree4 ,b "h1 in/ead ( repos+ on a mass ( /ratifi$ tuff1 ! c>bonace\s lay]s lie on "o ( ! b$d$ lavas4 ,! tuff has di$ out 9 ! int]v5+ ?ree miles1 yet t "s ( ! dis*>ges ( volcanic detritus rea*$ ev5 to ?is di/ance1 & t !y took place dur+ ! accumulation ( ^! lay]s ( mud & vegetation1 is %[n by ! occurr5ce 9 ! %ales ( pieces ( f9ely amygdaloidal basalt1 f less ?an an in* to six in*es 9 l5g?1 likewise lapilli ( a f9e m9utely cellul> basic pumice1 l "s v>ieties ( palagonite4 ,! ov]ly+ dol]ite 7c7 becomes f9ely prismatic at its junction ) ! s$im5t>y lay]s & has probably indurat$ !m4 ,illu/ration3 ,fig4 #cje4--,section ( ! ,volcanic ,s]ies at ,a* na ,hannait1 s\? ( ,portree1 ,skye4 ,?is int]calation ( a %aly & coaly b& among ! lavas c be foll[$ nor?w>d along ! coa/4 ,9 "s places x has be5 invad$ by dykes1 sills1 & ?reads ( basalt on ! mo/ rem>kably m9ute scale1 ( :i* ,i %all give "s acc\nt 9 ,*apt] xlii4 7see ,fig4 #cba74 ,nor? ( ,tianavaig ,bay--t is1 ab\t ?ree-qu>t]s ( a mile ne>] to ! ,portree v5t--a p]ceptible increase 9 ! am\nt ( volcanic mat]ial is obs]vable among ! %ales & leaf-b$s4 ,n only are lapilli ( basic pumice abundant1 b ! volcanic detritus has accumulat$ "h & !re 9 suffici5t am\nt to =m a b& ( dull gre5i%-br[n tuff4 ,^! coa/-sections 9 ! neighb\rhood ( ,portree af=d additional illu/rations ( ! *>act]i/ic fact1 on :i* ,i h already insi/$1 t ! int]/ratifications ( s$im5t>y mat]ial 9 ! basalt-plateaux frequ5tly t]m9ate upw>d 9 leaf-b$s1 ?9 coals1 or lay]s ( %ale1 full ( indi/9ctly pres]v$ rema9s ( plants4 ,z ,i h endeav\r$ to %[1 ?is vegetation1 :i* 0 und\bt$ly t]re/rial1 probably grew n f> f ! sites :]e its rema9s h be5 pres]v$4 ,leaves & se$s w\ld naturally be bl[n or wa%$ into pools on ! lava-fields1 & w\ld ga!r !re among ! mud & s& c>ri$ by ra9 f ! surr\nd+ gr\nd4 ,su* a topography & su* a sequ5ce ( ev5ts po9t to int]vals ( long] or %ort] duration betwe5 ! successive outp\r+s ( basalt4 ,x 0 probably dur+ "o ( ^! int]vals ( quietude t ! crat] ( ! ,portree volcano became a ma> & 0 f9ally silt$ up4 ,ref]5ce has already be5 made to a conspicu\s mass ( agglom]ate :i* occurs at ! ea/ end ( ! isl& ( ,canna1 & m>ks ! site ( an important volcanic v5t belong+ to ! ,small ,isles plateau4 ,a portion ( x projects f ! grassy slopes1 & rises v]tically above ! bea* z a picturesque crag1 9 front ( ! precipice ( ,compass ,hill 7,fig4 #cjf74 ,b ! same rock may be trac$ s\?w>d to ! ,coroghon ,mr1 & nor?-we/w>d 9 ! l[] "p ( ! cliffs to a little beyond ! sea-/ack ( ,an ,/ll4 ,x has ?us a diamet] ( at lea/ #cjjj feet4 ,we/w>d x passes "u ! conglom]ate describ$ 9 ,*apt] xxxviii4 ,its ea/]n ext5sion has be5 conceal$ by ! sea4 ,illu/ration3 ,fig4 #cjf4--,view ( "p ( a ,volcanic ,neck at ! ea/]n end ( ! isl& ( ,canna4 7,f a photograph by ,miss ,?om47 ,! mat]ials t fill ?is v5t consi/ ( a typical agglom]ate compos$ entirely1 or almo/ entirely1 ( volcanic detritus4 ,! emb$d$ blocks v>y up to eight feet 9 diamet] or ev5 m4 ,!y are *iefly fragm5ts ( v>i\s basalts & &esites1 g5]ally vesicul> or amygdaloidal4 ,"s ( ^!1 :i* h evid5tly be5 brok5 (f f already consolidat$ lavas1 are angul> or subangul> 9 %ape1 & _! /eam-holes are cut across by ! out] surfaces ( ! /ones4 ,:]e !y consi/ ( calcite1 zeolite1 etc41 ! amygdales s exactly resemble ^? ( ! b$d$ basalts ( ! plateaux t1 z already rem>k$1 we mu/ believe !m to h be5 already fill$ by infiltration be=e ! disruption ( ! rocks by volcanic explosions4 ,o!r blocks are true bombs1 ) a f9e-gra9$ cru/ outside & a m cellul> texture inside1 ! vesicles ( ! out] cru/ be+ sometimes dragg$ r\nd ! surface ( ! /one4 ,! v>iety ( mat]ials includ$ among ! eject$ blocks & ! abundance ( pieces ( ! r$ bole :i* s g5]ally sep>ates ! plateau-basalts indicate t a consid]able ?ickness ( b$d$ lavas has probably be5 brok5 ?r\gh by ! v5t4 ,beside ! volcanic mat]ials1 occasional angul> pieces ( r$ 7,torridon7 s&/one may be obs]v$ 9 ! agglom]ate4 ,! pa/e is a comm9ut$ mass ( ! same mat]ial z ! blocks1 tol]ably compact1 & entirely )\t any trace ( /ratification4 ,! actual m>g9 ( ?is v5t has n[h]e be5 detect$ by me4 ,we nev] rea* "h ! base ( ! volcanic s]ies1 = x is sunk "u ! sea-level4 ,on ! o!r h&1 ! upp] limits ( ! agglom]ate h be5 p>tially effac$ or obscur$ by ! conglom]ates :i* ov]lie x4 ,f ! bread? ( gr\nd across :i* ! agglom]ate c be foll[$ along ! %ore1 ! v5t might be reg>d$ z hav+ be5 p]haps n less ?an ?ree-qu>t]s ( a mile 9 diamet]4 ,b !re is ! same difficulty "h z at ! ,/ra? v5t 9 ,skye 9 det]m9+ ! actual limits ( ! volcanic funnel4 ,possibly !re may h be5 m ?an "o v5t 9 close proximity4 ,ev5 if !re 0 only "o1 ! exi/+ agglom]ate may include n only :at fill$ ! *imney1 b also a portion ( :at _h accumulat$ r\nd ! orifice & =m$ ! ext]nal cone4 ,t ! volcano cont9u$ = "s "t 9 vigor\s eruption may be judg$ f ! am\nt ( mat]ial eject$ f x1 ! l>ge size ( its blocks1 & ! di/ance to :i* !y 7 sometimes ?r[n4 ,! pieces ( ,torridon ,s&/one 7 no d\bt d]iv$ f ! ext5sion ( t =mation und]nea? ,canna4 ,on ! opposite isl& ( ,rum1 :]e ^! pre-,cambrian r$ s&/ones are copi\sly develop$1 !y =m ! plat=m ?r\gh :i* ! ,t]ti>y volcanic s]ies has be5 erupt$4 ,! sev]al rema9+ outli]s ( ! b$d$ basalts1 ref]r$ to 9 a previ\s *apt] 7p4 #bae & ,fig4 #bfg7 z visible on ! we/ side ( ?is isl&1 %[ t ! basalt-plateau ( ,small ,isles1 :i* once cov]$ t area1 re/$ imm$iately on ! incl9$ edges ( ! ,torridon ,s&/ones4 ,probably ! same /ructure /ret*es we/w>d "u ,canna & ,s&ay4 ,no traces ( any ,jurassic /rata h be5 detect$ b5ea? ! volcanic rocks ( ,rum1 ?\gh !y are s well develop$ a few miles to ! ea/ 9 ! isl& ( ,eigg4 ,ei!r !y 7 n deposit$ ov] ! pre-,cambrian rocks ( ,rum1 or !y _h be5 remov$ f t anci5t ridge be=e ! beg9n+ ( ! ,t]ti>y volcanic p]iod4 ,c]ta9ly ,i h n detect$ a s+le recognizable fragm5t ( any ,jurassic s$im5t>y rock 9 ! agglom]ate ( ,canna4 ,?is ,canna v5t exhibits1 bett] ?an is usually %[n1 ! occurr5ce ( dykes & irregul> injections ( lava ?r\gh ! agglom]ate4 ,a l>ge mass ( a f9ely column> basalt runs up f ! bea* at ,g>bh ,asg>ni%4 ,a simil> rock =ms sev]al deta*$ crags a little fur!r s\?1 p>ticul>ly 9 ! headl& ( ,coroghon ,mr & ! isl& ( ,alman4 ,"h ! basalt is beautifully column>1 its sl5d] prisms curv+ f a c5tral l9e until _! ends abut aga9/ ! agglom]ate4 ,! truly intrusive "* ( ?is basalt is well %[n on ! s\!rn front ( ,coroghon ,mr1 & on ! nor!rn face ( ,alman1 z repres5t$ 9 ! accompany+ diagrams 7,figs4 #cjg & #cjh74 ,illu/ration3 ,fig4 #cjg4--;,column> ,basalt invad+ ,agglom]ate ( ,volcanic ,v5t1 ,coroghon ,mr1 ,isle ( ,canna4 7,height above #bj feet47 ,illu/ration3 ,fig4 #cjh4--;,column> ,basalt invad+ ,volcanic ,conglom]ate1 nor? side ( ,alman ,islet1 ,canna4 ,al?\gh !re is no conclusive evid5ce t ^! intrusions belong to ! "t ( ! activity ( ! v5t1 yet !y diff] s mu* f ! ord9>y dykes 7"o ( :i* also cuts ! agglom]ate & asc5ds ?r\gh ! conglom]ates & basalts above71 are conf9$ s m>k$ly to ! v5t & its imm$iate proximity1 & resemble s closely ! basalt-injections ( o!r v5ts1 su* z ^? ( ! ,c>bonif]\s & ,p]mian necks ( ,scotl&1 t !y may ) probability be reg>d$ z "p ( ! me*anism ( ! ,canna volcano4 ,?\gh ! =m & size ( ! v5t ( ?is volcano _c be precisely def9$1 ! upp] "p ( its agglom]ate1 z we h se5 7ante1 p4 #bai71 is dovetail$ 9 ! mo/ int]e/+ way ) ! s]ies ( co>se conglom]ates1 :i* indicate /rong riv]-action 9 ?is "p ( ! volcanic area dur+ ! "t ( ! eruption ( ! plateau-basalts4 ,! agglom]ate v5ts describ$ 9 ! =ego+ pages z occurr+ 9 ,antrim & among ! ,inn] ,hebrides all appe> ei!r 9 ! mid/ ( ! plateau-basalts or 9 close proximity to !m4 ,be=e quitt+ ! ,scotti% examples1 ,i may ref] to "s t rise ?r\gh mu* m anci5t =mations at a di/ance f any portion ( ! volcanic plateaux1 & yet may ) probability be assign$ to ! ,t]ti>y volcanic p]iod4 ,dur+ ! progress ( ! ,geological ,survey ?r\gh ! di/rict ( ,applecross1 9 ! we/]n "p ( ! ma9l& ( ,ross-%ire1 & f> away f ! basalt-plateau ( ,skye1 ,mr4 ,john ,horne#cjf has f\nd two small necks ris+ on ea* side ( a l9e ( fracture1 ?r\gh g5tly incl9$ ,torridon ,s&/ones4 ,!y are conspicu\s f a di/ance by ! v]dure ( _! slopes1 9 contra/ ) ! br[n t9ts ( ! surr\nd+ moorl&4 ,! l>g] ( ! two necks measures ab\t #ahj by #aej feet1 & abruptly truncates ! b$s ( ,torridon ,s&/one1 :i* z !y approa* x assume a blea*$ aspect & become indurat$4 ,! mat]ial fill+ ?is v5t is an agglom]ate made up ma9ly ( pieces ( ,torridon ,s&/one & grit :i*1 ?\gh g5]ally small1 occasionally measure a foot across1 & 9 "o case 7 f\nd to rea* a l5g? ( f\r feet4 ,!y are n z a rule m>k$ly alt]$1 b "s ( !m h acquir$ a glaz$ or vitre\s texture4 ,besides ^! fragm5ts ( ! g5]al rock ( ! di/rict1 !re occur abundant lapilli ( a basic volcanic rock1 f\nd by ,mr4 ,teall to consi/ ( porphyritic felsp>1 extremely m9ute acicul> microlites ( felsp>1 some:at irregul> transp>5t spaces n[ occupi$ by a yell[i%-gre5 sub/ance1 & int]/itial matt]4 ,at ! s\? end ( ! v5t a small mass ( decay$ basalt appe>s to pi]ce ! agglom]ate4 ,footnote #cjf3 ,trans4 ,geol4 ,soc4 ,ed94 vii4 7#ahid71 p4 #ce4 ,illu/ration3 ,fig4 #cji4--,view ( neck-l mass ( breccia1 ,bro*el1 ,raasay4 ,?\gh !re is no indication ( ! age ( ^! necks1 !y agree s closely 9 g5]al "* ) kn[n v5ts ( ! ,t]ti>y volcanic plateaux t !re _c be mu* hesitation 9 reg>d+ !m z dat+ f ! same great p]iod ( basalt-eruption4 ,b no relic n[ exi/s any:]e ar\nd ( lavas or tuffs eject$ f !m4 ,!y rise on ! b>e ,applecross hills1 #ajjj feet above sea-level1 two miles f ! %ore1 & ab\t t5 miles f ! ne>e/ outli] ( ! basalt-plateau 9 ! ,dn ,c ( ,raasay4 ,if !y once dis*>g$ /reams ( lava t unit$ ) ! re/ ( ! plateau1 ! total de/ruction ( ?is lava af=ds ano!r impressive picture ( ! wa/e :i* ! volcanic rocks ( ! ,inn] ,hebrides h und]gone4 ,! l>ge proportion ( ,torridon ,s&/one blocks 9 ^! two ,applecross necks sugge/s1 h[ev]1 t ! orifices nev] became active volcanic v5ts4 ,!y may h be5 m]e spiracles1 or bl[-holes1 :]e ! funnels drill$ by explosive vap\rs 7 fill$ up ) ! debris ( ! rocks t 7 bl[n out4 ,b t lava did rise )9 !m is %[n by ! basic lapilli 9 ! agglom]ate1 & by ! basalt :i* 9 bo? v5ts has f\nd its way up ! *imney4 ,9 ! isl& ( ,raasay ,mr4 ,teall1 dur+ ! summ] ( #ahid1 obs]v$ a gr\p ( curi\s neck-l masses ( breccia :i* pi]ce ! ,torridon ,s&/one ne> ,bro*el 7,fig4 #cji74 ,! blocks 9 !m are l>ge angul> unalt]$ pieces ( ! surr\nd+ s&/ones & %ales1 sometimes t5 feet or m 9 l5g?1 & ! matrix is sometimes pure cry/all9e calcite l ,icel& sp>4 ,! breccia is g5]ally co>se/ t[>ds ! out] m>g94 ,b ?\gh ! ,lewisian gneiss exi/s imm$iately bel[ ! ?9 cake ( ,torridonian /rata1 n a fragm5t ( x c\ld ei!r ,mr4 ,teall or ,i1 :5 ,i visit$ ! locality ) him1 f9d among ! compon5ts ( ! breccia4 ,nor did we detect any trace ( volcanic mat]ial4 ,! g5]al gr\nd-plan ( ^! masses is elliptical1 ! mo/ nor!rly measur+ #cj y>ds 9 diamet]4 ,:]e ! junction ( ! breccia ) ! ,torridon /rata c be se5 x is a ne>ly v]tical "o1 ! s&/ones & %ales be+ mu* jumbl$ & brok51 b n s5sibly indurat$4 ,?is little clu/] ( pat*es ( breccia c h>dly be due to local cru%+ ( ! rocks4 ,_! def9ite outl9es & composition seem r to indicate spiracles ( ,t]ti>y "t1 :i* nev] became v5ts erupt+ lava or a%es4 ,! abs5ce ( fragm5ts ( ! und]ly+ gneiss may be acc\nt$ = if we suppose t ! orifices 7 completely cle>$ out by ! viol5ce ( ! explosions & 7 aft]w>ds fill$ up by ! fall+ 9 ( ! walls ( ! high] p>ts n[ remov$ by d5udation1 :i* consi/$ ( ,torridon ,s&/one & %ale4#cjg ,footnote #cjg3 ,x is on "o ( ^! neck-l pat*es ( breccia t ,bro*el ,ca/le /&s1 ( :i* ,maccullo* gave s s5sational a picture 9 "o ( ! plates ( 8 ,we/]n ,isles4 ,fur!r rese>* may detect at /ill great] di/ances f ! basalt-plateaux anci5t volcanic necks t might1 ) m or less probability1 be ref]r$ to ! ,t]ti>y p]iod4 ,z an in/ance ( ?is k9d1 ,i ref] to ! neck at ,bun[51 ,c\nty ,galway1 rec5tly describ$ by ,mr4 ,m',h5ry & ,pr(essor ,sollas4 ,?\gh s remote f ! ,t]ti>y basalt-plateaux1 ! rock ( ?is boss is an oliv9e-basalt pres5t+ a close resemblance to "s ( ! rocks ( ,antrim4#cjh ,footnote #cjh3 ,trans4 ,roy4 ,iri% ,acad41 #ahif4 ,z a f9al illu/ration ( ,t]ti>y volcanic v5ts ,i w n[ describe ! ,f>oe gr\p already allud$ to 7vol4 i4 p4 #fc1 vol4 ii4 p4 #bef74 ,x 0 almo/ by a k9d ( happy accid5t t ^! v5ts 7 discov]$4 ,notic+ at a di/ance ( a mile or m f ! deck ( a /eam-ya*t t ! base ( ! great basalt cliffs on ! we/ side ( ,/rom 7 v>i$ by :at look$ l agglom]ate1 ,i /eam$ in%ore1 & 0 delight$ to f9d1 z ! vessel drew ne> to ! cliff1 t ! agglom]ate assum$ def9ite b\nd>ies & occurr$ 9 sev]al di/9ct pat*es1 until at la/ x pres5t$ ! unmi/akable outl9es ( a gr\p ( v5ts und]ly+ & ov]spread by ! b$d$ basalts ( ! plateau4 ,fav\r$ by an unusually calm sea1 ,i 0 enabl$ to boat into e nook & r\nd e buttress & islet ( ?is "p ( ! coa/-l9e4 ,illu/ration3 ,fig4 #caj4--,view ( ,volcanic ,neck pi]c+ & ov]la9 by ! ,plateau-,basalts1 ,/rom1 entrance ( ,vaagfjord1 ,f>oe ,isl&s4 7,f a photograph by ,colonel ,evans47 ,! basalt-plateau "h pres5ts to ! we/]n ocean a ne>ly v]tical esc>pm5t :i* mu/ rea* a height ( at lea/ #ajjj feet 7see ,fig4 #cbh71 & displays a magnific5t section ( ! b$d$ lavas4 ,! l[] "p ( ?is section %[s *iefly ! b&$ /ructure already describ$1 ! lay]s ( diff]5t consi/5cy be+ et*$ out by ! wea!r 9 su* a way z to give !m ! look ( /ratifi$ rocks4 ,9 ! upp] "p ( ! precipice column> & jo9t$ or prismatic %eets are m common1 b ! mo/ prom95t b& is ! great sill1 to :i* fur!r ref]5ce w be made 9 ! next ,*apt]4 ,9 ! c\rse ( ! gradual retreat ( ! cliff1 z ! waves tunnel its base1 & slice aft] slice is deta*$ f its v]tical front1 a gr\p ( at lea/ five small v5ts has be5 uncov]$ ly+ along a ne>ly nor? & s\? l9e4 ,( two ( ^! a segm5t rema9s /ill on ! cliff-wall & passes "u ! basalts2 ! o!rs h be5 dissect$ & half cut away f ! cliff1 :ile gr\ps ( /acks & rocky islets ( agglom]ate may m>k ! position ( o!rs almo/ effac$4 ,! horizontal di/ance )9 :i* ! v5ts are cr[d$ is probably less ?an half a mile1 b ! l(ty proportions ( ! precipice t5d to lead ! eye to und]e/imate bo? heights & di/ances4 ,illu/ration3 ,fig4 #caa4--,section ( ! same ,neck z t %[n 9 ,fig4 #caj4 ,! agglom]ate is a ?or\ghly volcanic rock1 consi/+ ( l>ge & small blocks ( v>i\s basalts1 among :i* l>ge slags are specially conspicu\s1 ! :ole be+ wrapp$ 9 a granul> matrix ( comm9ut$ volcanic detritus4 ,! arrangem5t ( ?is mat]ial is be/ se5 9 ! f\r? v5t 7,figs4 #caj & #caa74 ,9 ?is *>act]i/ic volcanic neck 7b 9 ,fig4 #caa7 ! b\nd>y walls1 z laid b>e on ! face ( ! precipice1 are v]tical1 & are =m$ ( ! truncat$ ends ( ! b&$ lavas 7a a7 :i* h be5 bl[n out at ! "t ( ! =mation ( ! orifice4 ,! visible diamet] ( ! v5t 0 r\ghly e/imat$ by me to be ab\t #ajj y>ds4 ,no appreciable alt]ation 0 obs]v$ 9 ! ends ( ! lavas next ! v5t4 ,! agglom]ate is co>se/ 9 ! c5tre1 :]e huge blocks ( slaggy lava lie imb$d$ 9 ! amorph\s mass ( compact$ debris4 ,on ei!r side ( ?is /ructureless c5tral portion ! agglom]ate is di/9ctly /ratifi$ f ! walls t[>ds ! middle1 at angles ( #cj to #ce4 ,ev5 f a di/ance x c be obs]v$ t ! upp] limit ( ! agglom]ate is sauc]-%ap$1 ! slop+ sides ( ! depression dipp+ t[>ds ! c5tre ( ! neck at ab\t ! same angle z ! rudely-/ratifi$ agglom]ate und]nea?4 ,f ! bottom ( ?is bas9 to ! sea-level may be a v]tical di/ance ( "s #cj y>ds4 ,! bas9 itself has be5 fill$ up by ?ree successive fl[s ( basalt1 ( :i* ! fir/ 7c7 has m]ely ov]fl[$ ! bottom1 ! second 7d71 ent]+ f ! nor!rn rim ( ! bas91 ext5ds across to ! s\!rn slope1 :ile ! ?ird 7e71 also fl[+ f ! nor?1 has fill$ up ! rema9d] ( ! holl[ & ext5d$ completely across x4 ,! next succe$+ lava 7f7 /ret*$ ov] ! site 9 su* a way z to bury x entirely1 & to provide a level floor = ! pil+ up ( ! succe$+ %eets ( basalt4 ,illu/ration3 ,fig4 #cab4--,volcanic ,neck close to t %[n 9 ,figs4 #caj & #caa4 ,illu/ration3 ,fig4 #cac4--,section ( wall ( ano!r ,neck ( agglom]ate 9 ! same gr\p ) ^? repres5t$ 9 ,figs4 #caj1 #caa1 & #cab4 ,! second v5t1 :i* is repres5t$ 9 ,fig #cab1 exhibits ! same features1 b ) "s additional po9ts ( int]e/4 ,x measures r\ghly ab\t #bj y>ds 9 diamet] at ! sea-level1 rises ?r\gh ! same gr\p ( b&$ basalt 7a a71 & is fill$ ) a simil> agglom]ate 7b74 ,its m nor!rly wall is n[ co9cid5t ) a l9e ( fault 7h7 :i* asc5ds ! cliff1 & probably m>ks "s subsid5ce aft] ! eruptions _h ceas$4 ,! s\!rn wall %[s t a dyke ( basalt 7g7 has ris5 betwe5 ! agglom]ate & ! b&$ basalts1 & t a second dyke 7g7 trav]ses ! latt] at a di/ance ( a few feet4 ,9 ?is in/ance1 also1 ! upp] surface ( ! agglom]ate =ms a cup-%ap$ depression :i* has be5 fill$ 9 by two successive /reams ( lava 7c1 d74 ,among ! succe$+ lavas 7e7 ! prom95t sill 7f7 has be5 intrud$1 to :i* fur!r allusion is made on p4 #cbc4 ,^! necks are obvi\sly volcanic v5ts belong+ to ! "t ( ! basaltic eruptions4 ,!y h be5 drill$ ?r\gh ! basalts ( ! l[] "p ( ! cliff1 b h be5 buri$ "u ^? ( ! c5tral & high] p>ts4 ,! arrangem5t ( _! compon5t mat]ials 9 rude b$s dipp+ t[>ds ! middle ( ea* v5t %[s t ! eject$ du/ & /ones mu/ h fall5 back into ! orifice s z to be rudely /ratifi$ t[>ds ! c5tre ( ! *imney1 :i* 0 f9ally clos$ by its own la/ dis*>ges ( co>se detritus4 ,! sauc]-%ap$ upp] limit ( ! agglom]ate seems to indicate1 z has be5 sugge/$ above 9 ! case ( ! ,portree volcano1 t aft] ! eruptions ceas$ ea* v5t rema9$ z a holl[ or ma> on ! surface ( ! lava-fields4 ,& ! mann] 9 :i* !y are fill$ ) successive %eets ( basalt %[s t 9 c\rse ( "t o!r eruptions f neighb\r+ orifices gave =? /reams ( lava :i*1 9 fl[+ ov] ! volcanic fields1 ev5tually buri$ & oblit]at$ ea* ( ! v5ts4 ,illu/ration3 ,,to ,,accompany ,,sir ,,ar*ibald ,,geikie',s ,,anci5t ,,volcanoes ,,( ,,brita9 ,map ,,vi ,,map ,,( ,,! ,,t]ti>y ,,volcanic ,,region ,,( ,,! ,,inn] ,,hebrides ,! ,ed9burgh ,geographical ,in/itute ,copyright ,j4 ,g4 ,b>?olomew ,9 ! de/ruction ( ! precipice "s ( ! v5ts h be5 s mu* cut away t only a small "p ( ! wall is left1 ) a portion ( ! agglom]ate adh]+ to x4 ,! ?ird neck1 = in/ance1 af=ds ! section repres5t$ 9 ,fig4 #cac1 :]e ! horizontal %eets ( basalt 7a7 h /ill a k9d ( ?ick pellicle ( ! volcanic detritus 7b7 adh]+ to :at mu/ h be5 "p ( ! side ( ! orifice ( eruption4 ,! waves h cut out a cave at ! base1 s t we c1 by boat1 get beh9d ! agglom]ate & see ! m>g9 ( ! volcanic funnel 9 ! ro( ov]head4 ,! fragm5t ( geological hi/ory s picturesquely laid b>e on ! ,/rom cliffs pres5ts a significant illu/ration ( :at seems to h be5 a frequ5t1 if n ! normal type ( volcanic v5t 9 ! ,t]ti>y basalt-plateaux4 ,by ! =tunate accid5t t d5udation has n proce$$ too f>1 we are able to obs]ve ! orig9al tops ( at lea/ two ( ! v5ts1 & to see h[ su* volcanic orifices1 :i* 7 d\btless abundant all ov] ^! plateaux1 came to be entomb$ "u ! ev]-increas+ pile ( accumulat+ basalt4 ,!re is /ill "o feature ( int]e/ 9 ^! cliff-sections :i* des]ves notice "h4 ,e geologi/ :o has /udi$ ! composition ( ! basalt-plateaux has rem>k$ ! comp>atively insignificant "p play$ by tuffs 9 ^! volcanic accumulations4 ,hundr$s ( feet ( successive basalt-%eets may (t5 be exam9$ )\t ! discov]y ( any int]calation ( fragm5tal mat]ials1 & ev5 :]e su* int]calations d occur !y are = ! mo/ "p q ?9 & extremely local4 ,i f\nd x impossible to scale ! precipice = ! purpose ( asc]ta9+ :e!r ar\nd ! ,/rom v5ts1 & connect$ ) !m1 !re might n be "s b$s ( tuff int]/ratifi$ betwe5 ! basalts4 ,if su* b$s exi/1 !y c only be ( trifl+ ?ickness & ext5t4 ,"h1 !n1 are examples ( once active v5ts1 ! funnels ( :i* are /ill *ok$ up ) co>se fragm5t>y ejections1 yet f :i* little or no dis*>ge ( a%es & /ones took place ov] ! surr\nd+ gr\nd4 ,!y seem to h be5 left z crat]-l holl[s on ! b>e surface ( ! lava-fields4 ,,*apt] ,,xlii ,,! ,,basic ,,sills ,,( ,,! ,,basalt-,,plateaux ,we h n[ foll[$ ! di/ribution ( ! basalt-plateaux1 ! arrangem5t ( _! compon5t mat]ials :i* 7 erupt$ at ! surface1 & ! "* ( ! dyke-fissures & v5ts f :i* ^! mat]ials 7 eject$4 ,b !re rema9s to be consid]$ an ext5sive s]ies ( rocks :i* display "s ( ! und]gr\nd ph5om5a ( ! ,t]ti>y volcanoes4 ,! injection ( _m basaltic %eets _h be5 cle>ly en=c$ by ,maccullo*4 ,9 #ahga ,i po9t$ out t at diff]5t horizons 9 ! plateau-basalts1 b especially at _! base & among ! /ratifi$ rocks und]nea? !m1 %eets ( basalt & dol]ite occur :i*1 ?\gh ly+ p>allel ) ! /ratification ( ! volcanic s]ies1 are n truly b$d$1 b intrusive1 & !re=e y\ng] ?an ! rocks betwe5 :i* !y lie4#cji ,! non-recognition ( _! true nature _h l$ to _! be+ reg>d$ z pro(s ( volcanic int]calations 9 ! ,jurassic s]ies ( ,scotl&4 ,!re is1 h[ev]1 no trace ( ! true int]/ratification ( a volcanic b& 9 t s]ies1 e app>5t example be+ due to ! way 9 :i* intrusive %eets simulate ! *>act]s ( contemporane\s fl[s4 ,footnote #cji3 ,qu>t4 ,j\r4 ,geol4 ,soc4 xxvii4 7#ahga71 p4 #bif4 ,if su* %eets _h be5 met ) only at "o or two localities1 we might reg>d !m z due to "s m]e local accid5t ( /ructure 9 ! ov]ly+ cru/ ?r\gh :i* ! erupt$ mat]ial _h to make its way4 ,b :5 we f9d !m ev]y:]e f ! cliffs ( ,antrim to ! f> headl&s ( ,skye & ! ,%iant ,isles1 & see !m reappe> among ! ,f>oe ,isl&s1 x is obvi\s t1 l ^? ( ,palozoic "t1 !y mu/ be due to "s g5]al cause1 & t !y conta9 ! record ( a special p]iod or phase 9 ! build+ up ( ! ,t]ti>y volcanic tablel&s4 ,i w fir/ describe "s typical examples ( !m f diff]5t di/ricts1 & !n discuss _! probable relations ) ! o!r portions ( ! plateaux4 i4 ,,antrim ,fir/ to be exam9$1 & n[ mo/ famili> to geologi/s1 are ! rem>kable %eets t und]lie ! plateau ( ,antrim1 & project at v>i\s p>ts ( ! picturesque l9e ( coa/ betwe5 ,portru% & ,fair ,head4 ,f ! %ore at ,portru%1 z ,i h already rem>k$1 came ! evid5ce t 0 suppos$ to prove basalt to be a rock ( aque\s orig91 inasmu* z %ells 7 obta9$ !re f :at 0 believ$ to be basalt4 ,! long controv]sy to :i* ?is suppos$ discov]y gave rise is "o ( ! mo/ curi\s 9 ! hi/ory ( geology4#caj ,x cont9u$ ev5 aft] ! illu/ri\s ,playfair _h %[n t ! pret5d$ basalt 0 9 reality highly indurat$ %ale1 & h5ce t1 in/ead ( furni%+ pro( ( ! aque\s =mation ( basalt1 ! ,portru% sections only contribut$ ano!r /rong confirmation ( ! ,huttonian !ory1 :i* claim$ basalt to be a rock ( igne\s orig94 ,footnote #caj3 ,= an excell5t summ>y ( ?is controv]sy & an epitome ( ! descriptions ( ! ,portru% section1 see ! ,report on ! ,geology ( ,londond]ry1 etc4 7,mem4 ,geol4 ,survey71 by ,j4 ,e4 ,portlock 7#ahdc71 p4 #cg4 ,x is n[ well kn[n t ! rock :i* yield$ ! fossils is a ,liassic %ale1 t x is trav]s$ by sev]al %eets ( eruptive rock1 & t by contact-metamorphism x has be5 *ang$ into a highly indurat$ sub/ance1 break+ ) a spl9t]y1 con*oidal fracture1 b /ill reta9+ its ammonites & o!r fossils4 ,! eruptive mat]ial is a co>se1 di/9ctly cry/all9e dol]ite1 9 "s p>ts ( :i* ! augite1 p5etrat$ by la?-%ap$ cry/als ( plagioclase1 is rem>kably fre%1 :ile ! oliv9e has begun to %[ ! s]p5t9\s *ange along its cracks4#caa ,?is rock has be5 ?ru/ betwe5 ! b$d+ planes ( ! %ales1 b also breaks across !m1 & occurs 9 sev]al %eets1 ?\gh ^! may all be portions ( "o subt]ranean mass4 ,"s ( ! %eets are only a few in*es ?ick1 & might at fir/ be mi/ak5 = s$im5t>y alt]nations 9 ! %ale4 ,b _! mode ( wea!r+ soon enables ! obs]v] readily to di/+ui% !m4 ,x is to be notic$ t ^! ?9 lay]s ( eruptive mat]ial assume a f9e gra91 & resemble ! ord9>y dykes ( ! di/rict4 ,?is clos5ess ( texture1 z ,griffi? long ago po9t$ out1#cab is also to be notic$ along ! m>g9al portions ( ! ?ick] %eets :]e !y lie ^u or are cov]$ by ! %ales4 ,b away f ! surfaces ( contact1 ! rock assumes a co>s] gra91 insomu* t 9 its ?icke/ mass x pres5ts cry/als measur+ sometimes an in* 9 l5g?1 & !n ext]nally resembles a gabbro4 ,a m curi\s /ructure is %[n 9 "o ( ^! co>sely cry/all9e portions by ! occurr5ce ( a b& a few in*es broad :i* is /rongly amygdaloidal1 ! cells1 sometimes ?ree in*es or m 9 diamet]1 be+ fill$ ) zeolites4#cac ,! g5]al dip ( ! %ales & ( ! intrusive %eets :i* h be5 inject$ betwe5 !m is t[>ds ! ea/4 ,f und]nea? !m a ?ick mass ( dol]ite rises up to =m ! long promontory t "h projects nor?w>ds f ! coa/-l9e1 & is prolong$ seaw>ds 9 ! *a9 ( ! ,sk]ries4 ,footnote #caa3 ,dr4 ,f4 ,hat*1 ,explanation ( ,%eets #g & #h1 ,geol4 ,survey ( ,irel&1 p4 #dj4 ,footnote #cab3 ,address to ,geological ,society ( ,dubl91 #ahce1 p4 #ac1 ,j\r4 ,geol4 ,soc4 ,dubl91 vol4 i4 ,! v>ieties ( ! ,portru% rock 7 describ$ by ! late ,dr4 ,oldham1 9 ,portlock's ,report on ! ,geology ( ,londond]ry1 p4 #aej2 see also ! same "w = ,portlock's own rem>ks1 p4 #ig4 ,footnote #cac3 ,= a li/ ( ! m9]als 9 ?is rock1 see ,oldham1 op4 cit4 p4 #aea4 ,an int]e/+ feature ( ! ,portru% sections is ! cle> way 9 :i* !y exhibit ! ph5om5a ( segregation-ve9s--s *>act]i/ic ( ! ?ick] & m co>sely cry/all9e sills4 ,^! ve9s or seams "h diff] f ! re/ ( ! rock ma9ly 9 ! mu* l>g] size & m def9itely cry/all9e =m ( _! compon5t m9]als4 ,?\gh %>ply def9$1 :5 look$ at f a little di/ance1 !y are f\nd on clos] inspection to %ade into ! surr\nd+ rock by a complete int]lac+ ( cry/als4 ,on ! %ore1 !y c be se5 to lie1 on ! :ole1 p>allel ) ! b$d+ ( ! %eets 9 :i* !y occur1 b )\t rigidly foll[+ x1 s9ce !y undulate & ev5 ramify4 ,a good section across _! dip has be5 expos$ 9 a qu>ry ne> ! end ( ! promontory1 & %[s t !y are consid]ably less regul> ?an ! plan ( _! outcrop on ! %ore w\ld h l$ u to anticipate4 ,! accompany+ draw+ 7,fig4 #cad7 repres5ts ! ve9s laid b>e on a face ( rock n9e feet 9 l5g? by five feet 9 height4 ,x w be se5 t :ile !re is a g5]al t5d5cy to con=m to ! dip-slope1 :i* is "h f "r to left1 ! seams or lay]s unite into a l>ge rudely-b$d$ mass1 :i* s5ds out processes at diff]5t angles4 ,! peculi> aggregation ( m9]als :i* di/+ui%es su* ve9s is p]haps be/ se5 at ,fair ,head1 & ,i res]ve = ! description ( t locality :at ,i h to say on ! subject1 only rem>k+ ) reg>d to ! ,portru% rock t ! felsp> %[s a disposition to collect 9 ! c5tre ( ! ve9s ) ! augite & ! o!r d>k m9]als at ! out] m>g9s4 ,illu/ration3 ,fig4 #cad4--,view ( ,segregation-,ve9s 9 a dol]ite sill1 ,portru%1 ,antrim4 ,! contact-metamorphism at ?is locality is ( m hi/orical int]e/ 9 connection ) ! progress ( geological !ory ?an ( sci5tific importance4 ,x consi/s ma9ly 9 an int5se induration ( ! argillace\s /rata4 ,^! pass "h f _! usual condition ( fissile1 lam9>1 dull1 d>k %ales into an exce$+ly compact1 black1 fl9ty sub/ance1 :i* 9 its fracture1 col\r & h>dness rem9ds "o ( ,lydian /one4 ,yet ! ammonites & o!r organic rema9s h n be5 de/roy$4 ,!y are pres]v$ 9 pyrites4 ,illu/ration3 ,fig4 #cae4--,view ( ,fair ,head1 f ! ea/1 %[+ ! ma9 upp] sill & a ?9n] %eet cropp+ out along ! talus slope4 ,( all ! examples ( ,t]ti>y sills 9 ,brita9 few are m impos+ ?an t ( ! noble range ( precipices :i* =m ! promontory ( ,fair ,head4 ,leav+ out ( acc\nt ! m9or masses ( eruptive rock :i* occur und]nea? x1 we f9d ! ma9 %eet to ext5d along ! coa/ = ne>ly f\r miles1 to rise to a height ( #fcf feet above ! sea1 & to atta9 a maximum ?ickness ( #bej feet4 ,?is enorm\s b$ dies out rapidly bo? to ! ea/ & we/1 & seems also to ?9 away inl&4 ,se5 f ! nor?1 x /&s ^u a talus ( blocks z a %e] v]tical wall1 #bej feet high1 & ! rude prisms into :i* x is divid$ are cont9u\s f top to bottom 7,fig4 #cae74 ,s regul> is ?is prismatic /ructure1 & s mu* does x recall ! m m9ute column> gr\p+ ( ! b$d$ basalts1 t at a little di/ance we c h>dly realize ! true scale ( ! /ructure4 ,x is only :5 we /& at ! base ( ! cliff or scramble d[n its "o accessible gully1 ! ,grey ,man's ,pa?1 t we appreciate h[ long & ?ick ea* ( ! prisms actually is 7,fig4 #caf74 ,x may "h be rem>k$ t ?is regul> prismatic jo9t+ is "o ( ! di/+ui%+ features ( ! l>ge sills1 & s]ves to m>k !m (f f ! b$d$ basalts1 ev5 :5 ^! h assum$ a column> /ructure4 ,! prisms are mu* l>g] ?an ! basalt-columns1 & nev] display ! irregul> />*-l arrangem5t s common among ! plateau-basalts4 ,illu/ration3 ,fig4 #caf4--,view ( ,fair ,head f ! %ore4 7,f a ,photograph by ,mr4 ,r4 ,wel*47 ,! rock compos+ ?is magnific5t %eet is a co>sely cry/all9e1 ophitic1 oliv9e-dol]ite4#cad ,! same dim9ution ( ! compon5t cry/als1 :i* is s m>k$ along ! m>g9s ( ! eruptive masses at ,portru%1 is /rik+ly exhibit$ at ! bord]s ( ! ,fair ,head sill4 ,= ab\t #ah or #bj in*es upw>d f ! bottom1 :]e ! b$ re/s on ! black1 ,c>bonif]\s %ales1 ! dol]ite is d>k & f9ely cry/all9e1 wea!r+ sph]oidally 9 ! usual mann]4 ,b imm$iately above t bottom lay] ( clos] gra91 ! normal co>sely cry/all9e texture rapidly sup]v5es4 ,a simil> clos5ess ( gra9 is obs]vable at ! surfaces ( contact :]e ! %eet splits up on its we/]n bord]4 ,footnote #cad3 ,pr(essor ,judd has describ$ :at he calls a glom]o-porphyritic /ructure 9 ?is rock 7,qu>t4 ,j\rn4 ,geol4 ,soc4 xlii4 7#ahhf71 p4 #ga74 ,n[h]e1 s f> z ,i "k1 c ! ph5om5a ( segregation-ve9s be s in/ructively /udi$ z along ! abundant exposures ( ?is great %eet4 ,! ve9s are mo/ conspicu\s :]e ! rock occurs 9 ?icke/ mass4 ,!y v>y up to ?ree or f\r feet 9 ?ickness1 &1 z at ,portru% & else:]e1 lie on ! :ole p>allel to ! upp] & "u surfaces ( ! %eet4 ,an errone\s impression may be convey$ by ! t]m ve9s appli$ to !m4 ,!y are q z mu* lay]s1 p>allel on ! :ole ) ! b$d+ ( ! %eet1 yet n adh]+ rigidly to "o plane1 b pass+ across "h & !re f "o horizon to ano!r4 ,t !y are n due to any long subsequ5t protrusion ( y\ng] mat]ial ?r\gh ! ma9 %eet is made manife/ by ! ?or\gh int]lock+ ( _! compon5t cry/als ) ^? ( ! body ( ! rock 9 :i* !y lie4 ,! mat]ial t fills ^! ve9s has obvi\sly be5 introduc$ into !m :ile !re 0 /ill "s fre$om ( movem5t among ! cry/als ( ! surr\nd+ rock1 :i* mu/ ?us h be5 /ill n q consolidat$ & !re=e int5sely hot4 ,bo? cry/alliz$ sl[ly1 & 9 s do+ _! compon5t m9]als dovetail$ ) ea* o!r4 ,! con/itu5ts ( ! ve9s consi/ ( an exce$+ly co>se aggregate ( cry/als1 or r ( cry/all9e lumps ( ! same m9]als t con/itute ! g5]al mass ( ! rock1 ! felsp> & augite %[+ ! ophitic int]gr[? ( ! ma9 rock1 b on a f> l>g] scale4 ,"s ( ! pieces ( augite measure two in*es or m 9 diamet]4 ,! conditions "u :i* ^! ve9s 7 produc$ mu/ h diff]$ 9 "s ess5tial respects f ^? t prevail$ dur+ ! =mation ( ! f9e-gra9$1 highly silice\s ve9s already describ$ z occurr+ 9 "s dykes & sills4 ,?is great ,fair ,head sill lies ^u ,c>bonif]\s /rata1 b t x is to be class$ ) ! ,t]ti>y volcanic s]ies is1 ,i ?9k1 demon/rat$ by its relations to ! ,*alk at its ea/]n end4 ,x has !re brok5 ?r\gh t rock1 & conv]t$ x = a %ort di/ance into a :ite1 granul> m>ble4 ,b x is at ! we/]n side t ! mo/ int]e/+ sections occur to %[ ! truly intrusive nature ( ! mass4 ,! rock !re splits up into ab\t a doz5 %eets1 :i*1 keep+ g5]ally p>allel ) ea* o!r1 h =c$ _! way betwe5 & p>tly across ! b$d+ planes ( ! ,c>bonif]\s %ales 7,fig4 #cag74 ,9 ?is way ! huge1 unbrok5 mass1 #bej feet ?ick1 subdivides itself & disappe>s 9 a few hundr$ y>ds1 ?\gh x cont9ues a little fur!r inl&1 & approa*es ! %ore aga9 half a mile to ! s\?-we/4 ,fur!r evid5ce ( ! intrusive nature ( ?is rock may be obs]v$ along ! base ( ! precipice1 :]e at lea/ "o %eet #gj feet ?ick div]ges f ! ma9 mass & runs ea/w>ds betwe5 ! ,c>bonif]\s %ales 7,fig4 #cae74 ,at ! contact ) ! eruptive rock ! %ales are ev]y:]e mu* indurat$4 ,illu/ration3 ,fig4 #cag4--,section at ,f>rag&oo ,cliff1 we/ end ( ,fair ,head1 %[+ ! rapid splitt+ up & dy+ out ( an ,intrusive ,%eet4 a1 ,c>bonif]\s s&/one2 b1 ,c>bonif]\s %ale2 c1 intrusive %eet4 ii4 ,,skye ,all ?r\gh ! ,inn] ,hebrides ! base ( ! basalt-plateaux pres5ts abundant examples ( sills4 ,! g5]al p>allelism ( ^! intrusive %eets to ! b$d+ ( ! ,jurassic /rata among :i* !y lie has be5 above ref]r$ to z hav+ giv5 rise to ! errone\s conclusion t 9 ,skye & else:]e ! basalts are int]/ratifi$ ) ,jurassic rocks1 & are consequ5tly ( ,jurassic age4 ,x 0 ,maccullo* :o fir/ describ$ & figur$ 9 detail ! pro(s ( _! intrusive nature4 ,8 well-kn[n sections 9 plate xvii4 ( ! illu/rations to 8 "w on ! ,we/]n ,isl&s h be5 repeat$ly copi$1 & h s]v$ z typical figures ( intrusive igne\s rocks4 ,n[h]e 9 ,nor?-,we/]n ,europe c ! ph5om5a ( sills be /udi$ s fully & ) su* exub]ance & v>iety ( detail z 9 ! isl& ( ,skye & its surr\nd+ islets4 ,on ! we/]n coa/ ! great] subsid5ce ( ! basaltic plateau has = ! mo/ "p subm]g$ ! plat=m ( intrusive %eets1 ?\gh :]ev] ! base ( ! b$d$ lavas is br\ght up to ! surface ! accompany+ sills are expos$ to view4 ,! ea/ coa/ ( ! isl& has be5 classic gr\nd = ?is "p ( volcanic geology s9ce x suppli$ ! mat]ials = ,maccullo*'s descriptions & diagrams4 ,f ! m\? ( ,lo* ,sliga*an to ,rudha ,huni%1 at ! nor? end ( ,skye1 a s]ies ( sills may be trac$1 sometimes cr[n+ ! cliffs z a column> mural esc>pm5t1 sometimes burr[+ 9 endless ve9s & ?reads ?r\gh ! ,jurassic rocks4 ,! horizontal di/ance to :i* ?is cont9u\s b& ( sills ext5ds 9 ,skye is n f> %ort ( #cj miles4 ,b x /ret*es beyond ! limits ( ! isl&4 ,x =ms ! gr\p ( islets :i* prolongs ! geological /ructure & topographical features ( ,trott]ni% = #d miles fur!r to ! nor?-we/4 ,x reappe>s #aj miles /ill fur!r on 9 ! ,%iant ,isles4 ,?us its total visible l5g? is fully #dj miles1 or if we include "s outly+ sills ne> ! ,po9t ( ,sleat1 to be aft]w>ds describ$1 x ext5ds ov] a di/ance ( n less ?an #fj miles4 ,f ! la/ outli] 9 ,skye to ! sills ( ! ,isle ( ,eigg is a di/ance ( only #h miles1 !nce to ^? ( ,ardnamur*an #ag miles1 & to ^? ( ! s\? coa/ ( ,mull #be miles4 ,?us ?is plat=m ( intrusive %eets ( ! ,inn] ,hebrides c be int]rupt$ly foll[$ = a space ( n less ?an #aaj miles4 ,illu/ration3 ,fig4 #cah4--,view ( ! ,trott]ni% ,coa/1 %[+ ! position ( ! b& ( ,sills4 ,! d>k b& cr[n+ ! fir/ slope above sea-level m>ks a conspicu\s b& ( sills :i* t[>ds ! "r desc5ds to ! bea* & is prolong$ seaw>d 9 ! gr\p ( isl&s4 ,! ,/orr ,rock appe>s z a slant+ obelisk ( rock on ! hill to ! left4 ,?\gh none ( ! sills 9 ,skye itself atta9 ! dim5sions ( ! ,fair ,head %eet1 !y pres5t a great] v>iety ( rock & ( geological /ructure ?an is to be f\nd 9 ,antrim4 ,!y are specially develop$ at ! base ( ! ?ick1 ov]ly+1 basalt-plateau--a plat=m on :i* su* a prodigi\s quantity ( eruptive mat]ial has be5 inject$4 ,"p ( ?is mat]ial consi/s ( basic rocks 9 ! =m ( dykes1 ve9s1 or sills2 "p ( x is includ$ 9 ! int]m$iate & acid gr\ps1 & comprises ve9s1 %eets1 & bosses ( granitoid1 felsitic1 rhyolitic1 tra*ytic1 & pit*/one rocks4 ,"o ( ! peculi>ities ( ! ,skye sills is ! occurr5ce among !m ( comp\nd examples1 :]e %eets ( basic & acid mat]ial h be5 inject$ along ! same g5]al plat=m4 ,^! w be m specially ref]r$ to 9 ,*apt] xlviii4 ,) reg>d to ! basic sills 7dol]ites1 basalts1 etc471 ,i w\ld rem>k t :ile 9 ,we/]n ,scotl& ! ,antrim type ( %ort1 ?ick intrusions1 or laccolites1 is also f\nd1 ! va/ majority ( ! %eets are mu* ?9n]1 m p]si/5t1 & less easily di/+ui%able f ! b$d$ basalts4 ,illu/ration3 ,fig4 #cai4--;,column> ,sill intrusive 9 ,jurassic ,/rata ea/ ( ,kilm>t91 ,trott]ni%1 ,skye4 ,! high gr\nd to ! left is a portion ( ! basalt-plateau to ! nor? ( ! well-kn[n ,quira+4 ,9 describ+ ! sills ( ,skye ,i %all take fir/ ^? ( ! ea/]n & !n ^? ( ! we/]n side ( ! isl&4 ,along ! ea/ coa/1 f ,lo* ,sliga*an to ! mo/ nor!rly headl&s & islets ! sills play a notable "p 9 ! sc5]y1 inasmu* z !y cap ! great sea-cliff ( ,trott]ni% & run z a l9e ( ridges p>allel to ! tr5d ( ! coa/1 :ile ! plateau-basalts rise above !m fur!r inl& z a l(ty esc>pm5t1 :i* includes ! picturesque l&slips ( ! ,/orr ,rock & ,quira+ 7,figs4 #cah1 #cai74 ,b5ea? ! ?ick sills1 ! ,jurassic s&/ones =m a range ( pale yell[ precipices1 along :i* _m ?9n] %eets ( eruptive mat]ial h be5 intrud$4 ,z ,maccullo* well %[$1 _m ( ^! %eets1 if se5 only at "o po9t1 might readily be tak5 = regul>ly int]/ratifi$ b$s1 b p]haps only a few y>ds di/ant !y may be f\nd to break across ! /rata & to resume _! c\rse on a diff]5t level4 ,! sills ( ?is ,trott]ni% coa/ may be di/+ui%$ ev5 at "s di/ance f ! b$d$ basalts by ! regul> prismatic jo9t+1 already ref]r$ to1 & by _! frequ5tly great] ?ickness1 :ile on clos] inspection !y are *>act]iz$ by _! mu* co>s] texture4 ,!y are g5]ally some:at l>gely cry/all9e ophitic dol]ites1 gabbros or diabases1 & exhibit ! p]si/5t uni=mity ( composition & /ructure s *>act]i/ic ( intrusive %eets & dykes4 ,^! *>act]s are well exhibit$ 9 ! ,kilt ,rock1 a column> sill capp+ ! cliffs to ! s\? ( ,lo* ,/aff9 7,fig4 #cai74 ,^! massive sills are prolong$ 9 a s]ies ( picturesque flat tabul> islets beyond ! mo/ nor!rly headl&s ( ,skye4 ,!y probably cont9ue nor?w>ds "u ! sea at lea/ #ab miles fur!r1 = sills ( ! same type rise !re 9 ! s+ul>ly /rik+ gr\p ( ! ,%iant ,isles 7,fig4 #cbj74 ,^! lonely islets1 ext5d+ 9 an ea/ & we/ direction = ab\t ?ree miles1 display 9 great p]fection mo/ ( ! *ief *>act]s ( ! ,skye sills4 ,!y are especially notewor?y = includ+ ! ?icke/ intrusive %eet & ! noble/ column> cliff 9 ! :ole ( ! ,t]ti>y volcanic s]ies ( ,brita94 ,! l>g] ( ! two *ief isl&s consi/s ( two masses ( rock connect$ by a /rip ( %+le-bea*1 & hav+ a unit$ l5g? f nor? to s\? ( ab\t two miles4 ,! nor!rn half1 or ,g>bh ,eilean1 pres5ts t[>ds ! nor? a %e] precipice #ejj feet high4 ,?is magnific5t face ( rock consi/s ( "o s+le sill1 b z its orig9al upp] limit has be5 remov$ by d5udation & its base1 :]e x is ?icke/1 is conceal$ "u ! sea1 ! sill may exce$ #ejj feet 9 ?ickness4 ,! rock has ! usual prismatic /ructure1 :i* imp>ts to x an impressive appe>ance ( regul>ity4 ,! columns reta9 _! individuality to a great height1 & ?\gh none ( !m p]haps c be foll[$ f base to cre/ ( ! cliff1 _m ( !m are evid5tly at lea/ #cjj or #djj feet long4 ,maccullo*1 :o gave ! fir/ geological description ( ! ,%iant ,isles1 %[$ ! intrusive nature ( ! igne\s rocks1 & describ$ ! rem>kable globul> or botryoidal /ructure ( ! ,jurassic %ales betwe5 :i* !y h be5 inject$4#cae ,pr(essor ,h$dle has publi%$ a brief acc\nt ( ! geology ( ! isl&s4#caf ,pr(essor ,judd visit$ ! gr\p & br\ght away a s]ies ( specim5s ( _! eruptive rocks1 :i* he f\nd to include basic & ultra-basic v>ieties4#cag ,footnote #cae3 ,we/]n ,isl&s1 vol4 i4 p4 #dda4 ,footnote #caf3 ,trans4 ,norfolk ,nat4 ,hi/4 ,soc4 vol4 iii4 7#ahhj7 p4 #fa4 ,footnote #cag3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xxxiv4 7#ahgh7 p4 #fgg1 & xli4 7#ahhe7 p4 #cic4 ,my description 9 ! text is ! result ( ?ree successive visits to ! isl&s4 ,illu/ration3 ,fig4 #cbj4--,view ( ! nor!rn precipice 7#ejj feet high7 ( ! l>ge/ ( ! ,%iant ,isles4 7,f a ,photograph by ,colonel ,evans47 ,9 ,g>bh ,eilean1 :]e ! ?icke/ mass ( erupt$ mat]ial pres5ts itself1 at lea/ ?ree sills may be obs]v$4 ,"s l[ reefs t run p>allel ) ! nor!rn coa/ ( ! isl& consi/ ( co>se ophitic gabbro 9 two or m %eets :i* h be5 intrud$ betwe5 ! ,jurassic %ales4 ,above ^! /rata comes ! great column> sill1 its base gradually s9k+ t[>ds ! we/ until x passes "u ! sea1 & ! v]tical columns !n plunge abruptly into ! wat]4 ,! rock ( :i* ?is massive sill consi/s is ano!r l>ge-gra9$ gabbro or dol]ite1 ) an ophitic /ructure4 ,ow+ to ! =m ( ! gr\nd x _c be s satisfactorily exam9$ z ! neighb\r+ isl& ( ,eilean ,mhuire1 :i*1 ?\gh less l(ty & r small] ?an ,g>bh ,eilean1 af=ds a succession ( admirable & easily exam9$ sections along its precipit\s %ores4 ,pr(essor ,judd f\nd t :ile ! rocks are ma9ly ophitic gabbros & dol]ites1 !y include su* highly basic comp\nds z dunite4 ,an exam9ation ( ! ,eilean ,mhuire cliffs enables ! obs]v] to asc]ta9 t ! sills display consid]able v>iety 9 texture & 9 ! "* & arrangem5t ( _! compon5t m9]als4 ,!y are m>k$ by a p]si/5t1 m or less di/9ct disposition 9 rude b$s1 & ^! aga9 (t5 display a b&+ ( _! con/itu5ts 9 l9es p>allel ) ! g5]al b$d+4 ,"s ( ^! b&s are l>gely felspa?ic1 & are ?us pal] 9 col\r4 ,o!rs1 :]e ! f]ro-magnesian m9]als & ores are m specially aggregat$1 are d>k 9 col\r4 ,9 "s lay]s ! long black prisms ( augite are rang$ 9 a g5]al p>allelism ) ! b&+4 ,a specim5 select$ z typical ( ! ord9>y co>se-gra9$ amorph\s rock 0 slic$ & plac$ 9 ,mr4 ,h>k]'s = microscopic exam9ation1 & he has suppli$ ! foll[+ obs]vations reg>d+ x3 ,! gabbro f ,eilean ,mhuire #gaaj is a cry/all9e rock %[+ to ! eye lu/r\s black augites1 half an in* long1 & 7pr$om9at+7 felsp>4 ,! microscope reveals1 9 addition1 irregul> gra9s ( black iron-ore & little hexagonal prisms ( apatite4 ,no oliv9e is to be detect$4 ,z reg>ds /ructure1 ! augite has t5d$ to cry/allise out 9 advance ( ! felsp>1 b ?is relation is n con/ant4 ,! augite is ( a light-br[n t9t 9 slices1 & has an unusual k9d ( pleo*roism4 ,! col\r = vibrations p>allel to ! ,greek3 b-axis is ( ! purpli%-br[n tone se5 9 "s soda-be>+ augites2 p>allel to ,greek3 g & ,greek3 a x has a yell[ or citron t9t4 ,! col\r & pleo*roism are m m>k$ 9 ! int]ior ( a cry/al ?an t[>ds ! m>g91 b "s cry/als pass at ! m>g9 into a slightly pleo*roic1 pale-gre51 recall+ g]9e-augite4 ,! felsp> t5ds to build elongat$ cry/als4 ,x is a r f9ely lamellat$ labradorite1 sometimes %[+ p]icl9e- z well z albite-lamellae4 ,ano!r specim5 f "o ( ! black b&s 9 ! same isl&1 ) a l9e> arrangem5t ( its compon5t m9]als1 is ?us describ$ by ! same petrograph]3 ,?is rock #gaaa is ( d>k] appe>ance ?an ! prec$+1 & conta9s abundant black iron-ore1 besides "s pyrites4 ,x also diff]s 9 hav+ a m>k$ p>allel disposition ( its cry/als4 ,except = ! great] prom95ce ( l>ge irregul> gra9s ( iron-ore1 ?is rock "u ! microscope closely resembles ! la/ describ$1 ! p>allel /ructure n be+ conspicu\s 9 ! slice4 ,! augite has ! peculi> col\r & pleo*roism already not$1 & ! felsp> is ( ! same k9d z be=e4 ,i did n succe$ 9 f9d+ 9 place any b&s ( dunite1 b ?is basic mat]ial probably occurs at ! base ( "s ( ! sills :]e x has segregat$ f ! re/ ( ! mass1 l ! picrite at ! bottom ( ! ,ba?gate diabase4 ,! am\nt ( contact-metamorphism effect$ ev5 by su* ?ick sills z ^? ( ,trott]ni% & ,%iant is mu* less ?an might be expect$4 ,x seldom goes beyond a m]e induration ( ! /rata = a few y>ds1 (t5 only = a few in*es f ! surface ( junction4 ,9 ! ,%iant ,isles1 h[ev]1 ! %ales betwe5 ! sills h und]gone a m rem>kable alt]ation4 ,!y h n only be5 greatly indurat$1 b h acquir$ ! globul> or botryoidal /ructure s fully describ$ by ,maccullo*4 ,! sph]oidal aggregates v>y f n m ?an a l9e to m ?an half an in* 9 diamet]1 & appe> on ! surface z d>k1 irregul>ly gr\p$1 pea-l aggregates4 ,?is /ructure is p]haps be/ develop$ imm$iately "u ! ?ick sill on ! we/ side ( ,eilean ,mhuire4 ,! massive sills are n ! only evid5ce ( ! injection ( igne\s mat]ial on ! ,%iant ,isles4 ,! sill1 or m probably gr\p ( sills1 =m+ ,eilean ,mhuire is trav]s$ by a numb] ( %eets ( basalt v>y+ f only two or ?ree in*es to #bj feet 9 ?ickness4 ,^! black f9e-gra9$ rocks inv>iably pres5t *ill$ selvages next ! co>se gabbro1 & ?\gh !y h be5 on ! :ole inject$ p>allel to ! g5]al b$d+ or b&+1 !y "h & !re break across x z ve9s4 ,! mo/ important ( ^! lat] intrusions =ms a column> sill on ! ea/]n side ( ! isl&1 & c be foll[$ = sev]al hundr$ y>ds4 ,x consi/s ( a d>k f9ely cry/all9e oliv9e-basalt1 :i* t[>ds ! m>g9 assumes a d5se black texture4 ,"u ! microscope ,mr4 ,h>k] f\nd a ?9 slice ( ?is rock to be an oliv9e-basalt ( semi-ophitic1 semi-granulitic /ructure #gaab4 ,! oliv9e is mo/ly fre%1 b "p ( x is conv]t$ into a yell[i%-br[n pseudomorph l idd+site4 ,magnetite occurs *iefly 9 imp]fect octoh$ra4 ,! felsp> is 9 little la?-%ap$ sections1 _m ( :i* are f9ely /riat$1 & give ext9ction-angles indicat+ a labradorite4 ,! augite1 light br[n 9 ! slice1 nev] has cry/al-b\nd>ies1 & (t5 enwraps ! felsp>s4 ,! n>r[ ve9s are compos$ ( a mu* clos]-gra9$ basalt 9 :i* a few scatt]$ felsp>s are visible4 ,mr4 ,h>k] rem>ks1 ) reg>d to a ?9 slice ( "o ( ^! rocks #gaac1 t ! microscope %[s ?is1 too1 to be an oliv9e-basalt4 ,! porphyritic felsp>s are tw9n$ on ! ,c>lsbad & albite laws4 ,oliv9e & pseudomorphs aft] x are well repres5t$4 ,magnetite is only sp>+ly pres5t4 ,! g5]al mass ( ! rock consi/s ( v small /riat$ prisms ( labradorite1 granules ( augite1 & int]/itial matt] :i* mu/ be p>tly glassy4 ,?is is p]haps ! mo/ /rik+ ( all ! examples kn[n to me :]e an old] sill has be5 split op5 to receive a subsequ5t injection ( molt5 mat]ial4 ,! ,eilean ,mhuire gabbro mu/ be at lea/ #bjj feet ?ick1 & x n impossibly passes "u ! /ill ?ick] pile ( ,g>bh ,eilean4 ,yet x has be5 horizontally ruptur$ ne> its base1 & into ! r5t ?us produc$ ano!r mass ( molt5 matt] has be5 ?ru/4 ,?is subject w be aga9 ref]r$ to 9 connection ) ano!r rem>kable example on ! we/ coa/ ( ,skye4 ,illu/ration3 ,fig4 #cba4--,section ( ?9 ,intrusive ,%eets & ,ve9s 9 c>bonace\s %ales ly+ among ! ,plateau-basalts1 cliffs nor? ( ,a* na ,hannait1 betwe5 ,portree ,bay & ,lock ,sliga*an4 ,9 contra/ to su* enorm\s ?icknesses ( intrusive mat]ial z ^? ( ,trott]ni% & ! ,%iant ,isles1 in/ances may be cull$ f ! same belt ( sills :]e ! molt5 rock has be5 inject$ 9 ?9 leaves & m]e ?reads into ! ,jurassic s&/ones & %ales1 or into ! %ales & coals int]calat$ among ! plateau-basalts4 ,?us1 on ! cliff imm$iately to ! nor? ( ,a* na ,hannait1 betwe5 ,lo* ,sliga*an & ,portree ,bay1 ! section may be se5 :i* is repres5t$ 9 ,fig4 #cba4 ,at ! base lies a vesicul> dol]ite ) a slaggy upp] surface 7a74 ,next comes a zone ( s$im5t>y mat]ial ab\t five or six feet ?ick1 ! l[] portion consi/+ ( an impure coal1 :i* passes t[>ds ! "r h& into br[n & grey c>bonace\s %ale ) plant-rema9s 7b74 ,?is coaly lay] has be5 already allud$ to z probably ly+ on ! same horizon ) ! coal ( ,portree 7p4 #bhh74 ,trac$ nor?w>d1 x is f\nd to h a b$ ( f9e tuff b5ea? x1 & sometimes a volcanic breccia or conglom]ate4 ,x fills up r5ts 9 ! und]ly+ slaggy lava1 & 0 und\bt$ly deposit$ ^u ! cool$ surface ( t rock4 ,imm$iately above ?is l[] b& ! black c>bonace\s %ale :i* foll[s has be5 invad$ by an extraord9>y numb] ( ?9 cakes or sills & also by ve9s or ?reads ( basalt4 ,= a ?ickness ( two or ?ree feet ! b& 7d7 consi/s ma9ly ( ^! intrusions1 :i*1 9 ! =m ( a f9e grey basalt1 v>y f less ?an an in* to ?ree or f\r in*es 9 ?ickness4 ,!y are sep>at$ by ?9 p>t+s ( coaly %ale1 & z !y t5d to break up into deta*$ nodule-l portions1 especially t[>ds ! "r h& ( ! section1 !y might1 on casual inspection1 be easily mi/ak5 = nodules 9 ! d>k %ales4 ,some:at lat] 9 ! "t ( intrusion are ve9s ( basalt :i*1 z at c1 break across ! nodul> sills1 & sometimes exp& into ?ick] b$s 7c74 ,i h nev] se5 su* a cong]ies ( m9ute sills among ! ,t]ti>y basalt-plateaux z t "h exhibit$4 ,9 a space ( ab\t ?ree feet ( v]tical height !re mu/ be m ?an a doz5 ( r\ghly p>allel leaves ( intrusive rock4 ,ve9s 7e7 run up f ! *ief b& ( eruptive mat]ial into ! ov]ly+ f9ely vesicul> basalt 7f74 ,! dyke 7g7 is probably ! y\nge/ rock 9 ! section4 ,! m g5]al & ext5sive subm]g5ce ( ! base ( ! basalt-plateau on ! we/ side ( ,skye has = ! mo/ "p c>ri$ ! plat=m ( sills bel[ sea-level1 s t x is only exceptionally :]e1 ow+ to local irregul>ities1 t base has be5 br\ght up to ! air1 t ! intrusive %eets %[ !mselves4 ,yet ! p]si/5ce ( ! plat=m on t side is indicat$ by its ext5sion ev5 z f> z ! s\!rn promontory ( ! isl&4 ,! ,trott]ni% type ( sill ext5ds d[n ! we/ coa/ "u ! headl&s ( ,duir9i%4 ,?us at ! m\? ( ,dunvegan ,lo*1 :]e ! und]ly+ ,jurassic plat=m has be5 ridg$ up above ! surface ( ! sea1 x has c>ri$ ) x ! m>k$ sill :i* =ms ! islets ( ,m+ay & ,clett t lie z a protect+ breakwat] across ! entrance ( ! inlet4 ,! intrusive rock re/s on %ell-lime/ones full ( oy/]s 7,o/rea hebridica71 & ref]able to ! ,lo* ,/aff9 gr\p ( ! ,great ,oolite ,s]ies4 ,?is sill1 :5 obs]v$ f a little di/ance1 pres5ts ! usual regul>ly prismatic or column> /ructure s well develop$ among ! ,trott]ni% examples1 b on a clos] view %[s ?is /ructure less di/9ctly4 ,x is an oliv9e-dol]ite ( m$ium & f9e texture1 :i* 9 ?9 slices displays "u ! microscope a di/9ctly ophitic /ructure1 ! abundant light-br[n augite enclos+ ! /riat$ felsp>s4 ,its l[e/ portion1 f ?ree to sev5 or eight in*es upw>d f ! bottom1 is mu* clos]-textur$ ?an ! re/ ( ! rock & is f9ely amygdaloidal4 ,its vesicles are 9 _m cases drawn out to a l5g? ( ?ree or f\r in*es1 & ! zeolites :i* n[ fill !m look l p>allel annelid tubes or /ems ( ,li?o/rotion4 ,x is notewor?y also t ! elongation ( ! vesicles has sometimes tak5 place at a "r angle to ! surface ( contact ) ! und]ly+ /rata4 ,b ! mo/ rem>kable feature 9 ?is sill is ! surface :i* x pres5ts to ! oy/]-b$s on :i* x re/s4 ,! f9e-gra9$ d>k dol]ite has !re assum$ ! aspect ( a %eet ( iron-slag1 ) a smoo? or wr9kl$1 twi/$1 ropy surface1 :i* displays f9e curv+ fl[-l9es4 ,no "o look+ at a deta*$ specim5 ( ?is surface w\ld be ready to admit t x c\ld possibly h come f any?+ b a true lava-/ream t fl[$ out at ! surface4 ,! cont\rs ( a visc\s lava are "h precisely reproduc$ on ! "u surface ( a massive sill4 ,a little fur!r s\?1 ! promontory ( ,ei/1 =m+ ! we/]n breakwat] ( ,moon5 ,bay1 consi/s ( an important sill or gr\p ( sills :i* has ins9uat$ itself among %ales1 %ell-lime/ones1 & %aly s&/ones1 full ( ,o/rea hebridica1 ,cyr5a aurata1 etc41 & belong+ to ! ,lo* ,/aff9 gr\p ( ! ,great ,oolite ,s]ies4 ,! %ore-cliff bel[ ! wat]fall af=ds ! section giv5 9 ,fig4 #cbb1 illu/rat+ ! mann] 9 :i* a ?ick intrusive %eet may sometimes give (f ?9 ve9s f its mass4 ,! rock atta9s on ! ,ei/ promontory a ?ickness ( probably at lea/ #ajj feet1 :]e x is ?icke/ & undivid$4 ,b ! two ma9 %eets1 or bran*es ( "o great %eet1 on ?is p59sula h probably a unit$ dep? ( m ?an #cjj feet4 ,l&w>ds ! rock splits up & encloses cakes ( ! ,jurassic /rata4 ,x possesses ! usual prismatic /ructure & dol]itic composition4 ,9 ,moon5 ,bay1 z %[n 9 ,fig4 #cbb1 x pres5ts a b&$ /ructure1 m>k$ especially by an alt]nation ( l9es ( amygdales & lay]s ( m compact & solid dol]ite1 ) occasional enclos$ cakes ( bak$ %ale or s&/one4 ,its upp] surface is some:at unev51 & f x are giv5 (f n>r[1 wavy1 ribbon-l ve9s 7d71 f less ?an an in* to ?ree in*es or m 9 wid?1 :i* keep 9 a g5]al s5se p>allel to ! top ( ! sill1 b at a di/ance ( a few in*es or feet f x4 ,! sill becomes z usual f9e-gra9$ t[>ds ! contact1 ! %ales & s&/ones be+ indurat$ & ! lime/one m>moriz$4 ,illu/ration3 ,fig4 #cbb4--,upp] "p ( ,sill1 ,moon5 ,bay1 ,wat]ni%1 ,skye1 %[+ ! div]g5ce ( ve9s4 a1 false-b$d$ %aly s&/one2 b1 %ell-lime/one2 c1 dol]ite sill2 d1 ve9s proce$+ f ! sill4 ,l5g? ( section ab\t five y>ds4 ,! next uprise ( ! base ( ! basalt-plateau on ! we/ side ( ,skye lies ab\t #be miles to ! s\?-ea/1 :]e x em]ges f ! sea 9 ! ,s\nd ( ,soa 7,fig4 #cbc74 ,a va/ volcanic pile has !re be5 heap$ up on ! ,torridon s&/one1 ! :ole ( ! ?ick ,jurassic s]ies1 :i* is f\nd 9 =ce only ?ree miles di/ant 9 ,/ra?aird1 hav+ be5 remov$ by d5udation f ?is area be=e ! beg9n+ ( ! ,t]ti>y volcanic p]iod4 ,! plateau-basalts re/s on ! upturn$ edges ( ! ,torridonian s&/ones & %ales1 & are accompani$ z usual by _! und]ly+ network ( intrusive rocks4 ,x is h>dly possible to exagg]ate ! wild confusion ( sills1 dykes & ve9s :i* h be5 inject$ among ! rocks1 at & on bo? sides ( ! uncon=mability4 ,endless %eets ( basalt & dol]ite h =c$ _! way betwe5 ! b$d$ basalts & ! s&/ones1 :ile across ! :ole rise va/ numb]s ( dykes & ve9s4 ,n>r[1 black1 wavy ribbons ( basic mat]ial cross _m ( ^! ve9s1 :ile ! lat] nor?-we/ dykes cut %>ply ?r\gh ev]y?+ old] ?an !mselves4 ,z a natural section = ! /udy ( ! ph5om5a ( intrusion 9 _m ( _! mo/ *>act]i/ic phases1 ,i "k no locality equal to ! nor!rn coa/-l9e ( ! ,s\nd ( ,soa1 unless x be ! cliffs ( ,ardnamur*an4 ,b ! ,skye cliffs1 ?\gh less impos+ ?an ^? ( ! great ,argyll%ire headl&1 h ?is advantage1 t in/ead ( be+ expos$ to ! full roll ( ! op5 ,atlantic1 !y =m ! m>g9 ( a comp>atively %elt]$ /rait1 & c ?us be conv5i5tly exam9$4 ,illu/ration3 ,fig4 #cbc4--,section ( ! base ( ! ,basalt-plateau ) sill & dykes1 ,s\nd ( ,soa1 ,skye4 a a1 ,torridon ,s&/one2 b1 ,b$d$ basalts2 c1 ,sill2 d d1 ,dykes4 ,foll[+ /ill ! we/]n seabo>d ( ,skye1 we meet ) o!r /rik+ examples ( sills at a di/ance ( "s eight miles 9 a /raight l9e ea/w>d :]e1 betwe5 ,lo*s ,slap9 & ,ei%ort1 ! prom95t headl& ( ,suisni% juts out into ! sea4 ,?is promontory has long be5 kn[n to geologi/s f ! section ( x giv5 by ,maccullo* z an in/ance ( ! connection betwe5 ov]ly+ rocks & dykes4 ,i h already allud$ to x 9 t relation1 & ref] to x aga9 z an example ( "o ( ! ?ick] intrusive %eets ( ! ,inn] ,hebrides4 ,d5udation has "h also proce$$ s f> t ! :ole ( ! volcanic plateau has be5 /ripp$ (f1 only "s ( ! und]ly+ sills be+ left1 toge!r ) ! plat=m ( old] rocks betwe5 :i* & ! vani%$ basalts !y 7 inject$4 ,mo/ ( ^! sills consi/ ( granophyres belong+ to ! acid gr\p ( rocks to be aft]w>ds describ$4 ,b basic %eets occur n infrequ5tly int]pos$ betwe5 ! granophyres & ! subjac5t ,lias1 & sometimes ev5 int]calat$ 9 ! =m] rock4 ,?\gh at fir/ sight x might be ?\ght t ^! sills _h ins9uat$ !mselves aft] ! eruption ( ! granophyre1 & !re are in/ances :]e ?is _c be %[n n to be ! case1 ,i h obta9$ s _m pro(s ( ! invasion ( ! basic by ! acid rock t ,i h no d\bt ! =m] is1 z a g5]al rule1 ! old] ( ! two4 ,! ,suisni% headl& exhibits ! /ructure repres5t$ 9 ,fig4 #bdi4 ,= ab\t #cjj feet above ! sea-level ! /eep grassy slope %[s outcrops ( ! d>k1 s&y %ales & yell[i% br[n1 %aly s&/ones ( ! ,lias :i* =m ! range ( cliffs to ! ea/w>d4 ,^! g5tly incl9$ /rata are cut ?r\gh by _m v]tical basalt-dykes1 "s ( :i* int]sect ea* o!r1 b among :i* by f> ! l>ge/ is ! mass %[n 9 ! figure4 ,?is broad dyke consi/s ( a dol]ite or gabbro ! l>gely cry/all9e texture ( :i* m>ks x (f at once f ! o!rs1 :i* are ( ! usual d>k1 heavy1 f9e-gra9$ type1 ) an occasional less basic & porphyritic v>iety4 ,trac$ up f ! sea-m>g91 ! dyke loses itself 9 a talus ( blocks f ! cliff above1 s t its actual junction ) ! mural front ( ! sill _c be se54 ,b t x jo9s t mass1 ) :i* x agrees 9 petrographical *>act]s1 h>dly admits ( "q4 ,! cliff consi/s ( a ?ick %eet ( co>sely cry/all9e dol]ite or gabbro 7d 9 ,fig4 #bdi71 :i* 9 its g5]al aspect at once recalls ! rock ( ,fair ,head4 ,x v>ies consid]ably 9 texture1 "s p>ts ( ! mass are exce$+ly co>se1 l ! ,skye gabbros1 & pres5t a fibr\s /ructure 9 _! augite resembl+ t ( ! diallage 9 ^! rocks2 o!r portions assume ! compactness ( basalt4 ,a specim5 ( m$ium gra9 "u ! microscope %[s ! typical ophitic /ructure s g5]ally f\nd among ! dol]ites bo? ( ! plateaux & ( ! intrusive %eets4 ,?is sill mu/ be ab\t #bjj feet ?ick1 & l ! rock at ,fair ,head is trav]s$ f top to bottom by jo9ts t divide x into prisms4 ,x appe>s to bifurcate ea/w>d1 "o portion runn+ ) a tol]ably uni=m ?ickness ( a few feet z a prom95t b& at ! top ( ! %ales & s&/ones1 ! o!r slant+ upw>ds & gradually ?9n+ away 9 ! granophyre4 ,t[>ds its base1 ne> ! contact ) ! und]ly+ %ales1 ! rock z usual becomes f9] gra9$1 & ! ?9 b& j ref]r$ to resembles 9 texture "o ( ! wid] basalt-dykes4 ,we/w>ds ! rock c be foll[$ r\nd ! top ( ! grassy slopes =m$ by ! decay ( ! %ales4 ,?\gh conceal$ by int]vals ( moorl& & peat1 x is visible 9 ! /ream sections1 & ,i ?9k mu/ be cont9u\s1 z a b& only a few y>ds ?ick1 r\nd ! nor!rn side ( ! hills z f> z ,be9n ,bhuidhe1 :]e a simil> sill makes a prom95t crag4 ,its total area measures a mile & a qu>t] 9 l5g? by half a mile 9 bread?4 ,! granophyre :i* ov]lies x =ms "p ( an int]e/+ s]ies ( %eets :i* ,i h trac$ all ! way f ,suisni% to ! braes above ,skulamus4 ,:e!r or n ! :ole %eet ( basic rock is cont9u\s1 & :e!r x all proce$$ f ! great ,suisni% dyke1 _c be confid5tly decid$ until ! gr\nd is mapp$ 9 detail1 ?\gh f ! great ?ickness ( ! sill at ! dyke1 its att5uation outw>ds f t c5tre & its uni=mity ( petrographical "*1 ,i am dispos$ to answ] affirmatively4 ,!re is no o!r probable v5t to be se5 9 ! neighb\rhood1 unless a massive dyke t runs f ,lo* ,fada nor?-we/w>ds into ,gl5 ,bor]aig c be s reg>d$4 ,n f> f ! extreme s\!rn po9t ( ,skye a s+ul>ly int]e/+ example ( a sill rema9s z a deta*$ survival ( ! basaltic plateau & its accompanim5ts4 ,9 8 map ( ,skye1 ,maccullo* %[$ ! position ( ?is outli]1 :i* he class$ ) ! g5]al trap =mation ( ! isl&4 ,! locality 0 visit$ by ,pr(essor ,judd1 :o reg>d$ ! intrusive rock z a phonolite#cah ,9 #ahid1 dur+ an excursion ) my colleague ,mr4 ,c4 ,t4 ,cl\gh1 ,i _h an opportunity ( exam9+ ! rocks & collect+ notes = ! foll[+ acc\nt ( !m4 ,footnote #cah3 ,qu>t4 ,j\r4 ,geol4 ,soc4 vol4 xxxiv4 7#ahgh7 p4 #fib4 ,at ,rudh' an ,iasgai*1 ab\t two miles f ! ,po9t ( ,sleat1 a small outli] ( conglom]ate lies on ! edges ( ! ,torridon ,s&/one4 ,?is deposit has be5 correctly id5tifi$ by ,pr(essor ,judd ) ! simil> /rata :i*1 9 ,skye & else:]e on ! we/ coa/ ( ,scotl&1 und]lie ! ,liassic s]ies4 ,x is "h ab\t #aj or #ab feet ?ick1 r$di% & yell[i% 9 col\r1 & di/9ctly calc>e\s4 ,its compon5t pebbles consi/ l>gely ( ,cambrian 7,durness7 lime/one1 qu>tzite1 & ,torridon ,s&/one--rocks :i* all occur 9 situ 9 ,sleat4 ,x may be comp>$ ) ! lime/one conglom]ates ( ,/ra? & ^? :i* und]lie ! ,lias at ,hea/ on ,lo* ,ei%ort4#cai ,t "h1 z else:]e 9 ?is region1 ! basem5t conglom]ate 0 foll[$ by ! re/ ( ! ,lias & ,oolites may be inf]r$ ) "s confid5ce f ! copi\s developm5t ( ! ,jurassic s]ies a few miles (f1 bo? to nor? & s\?4 ,b ! :ole ( ?is ov]ly+ succession ( =mations has "h be5 swept away1 &1 b = ! protection af=d$ by ! eruptive rocks ( ,rudh' an ,iasgai*1 ! conglom]ate w\ld likewise h disappe>$4 ,footnote #cai3 ,op4 cit4 vol4 xiv4 7#aheg71 p4 #i2 vol4 xliv4 7#ahhh71 p4 #ga4 ,illu/ration3 ,fig4 #cbd4--,section ( ,dol]ite ,sill cut by ano!r sill1 bo? be+ trav]s$ by dykes1 ,rudh' an ,iasgai*1 we/]n side ( ,sleat1 ,skye4 ,above ! conglom]atic b& lies a %eet ( intrusive rock1 :i* 9 "o place has app>5tly cut x out1 s z to re/ directly ^u ! ,torridon ,s&/one 7a1 ,fig4 #cbd74 ,! decay ( ! s(t] detrital rock und]nea? has caus$ ! sill to break (f 9 slices1 :i* h left beh9d !m a bold mural esc>pm5t 7b b74 ,! rock ( ?is sill is a r co>sely cry/all9e porphyritic oliv9e-dol]ite1 :i* t[>ds ! nor? atta9s a ?ickness ( ab\t #gj feet4 ,x exhibits ! usual prismatic jo9t+1 b less p]fectly ?an "s ( ! ,trott]ni% sills already ref]r$ to4 ,besides ^! v]tical jo9ts1 x is also trav]s$ by a sy/em ( horizontal divisional planes :i*1 ?\gh some:at irregul> 9 _! c\rse1 run1 9 a g5]al s5se1 p>allel to ! upp] & "u surfaces ( ! sill4 ,x seems to h be5 along ?is transv]se s]ies ( jo9ts t a second sill 7c71 five or six feet ?ick1 has be5 inject$4 ,! mat]ial ( ?is y\ng] intrusion is a black1 f9ely cry/all9e dol]ite or basalt1 ) rudely prismatic jo9t+4 ,its mo/ /rik+ feature1 besides its regul>ity ( position & p]si/5cy = sev]al hundr$ y>ds z a plat=m along ! %ore1 is ! basalt-glass :i* m>ks bo? its "u & upp] surfaces ( contact1 & :i* is "h develop$ ^u a scale to :i* ,i h n met ) an equal among ! ,t]ti>y sills ( ?is c\ntry4 ,! selvage ( glass appe>s z a black t>-l lay]1 v>y+ f a m]e film to two or ?ree in*es 9 ?ickness4 ,x is f\nd n only on ! upp] & "u surfaces1 b desc5ds along abrupt /ep-l int]ruptions ( ! upp] surface1 a foot or m 9 height1 z if ! sill _h be5 brok5 by a s]ies ( subsid5ces4 ,! app>5t fracture1 h[ev]1 is probably due to ! irregul>ities ( ! passage =c$ = itself by ! molt5 rock z x pass$ f "o l9e ( horizontal jo9t to ano!r ?r\gh ! he>t ( ! old] %eet4 ,! expos$ surface ( black glass on ! top ( ! y\ng] sill exhibits long p>allel l9es1 probably m>k+ fl[-/ructure1 :i* are made conspicu\s by a pale yell[ f]rug9\s wea!r$ cru/4 ,portions ( ! l>g] intrusive %eet h be5 brok5 (f & involv$ 9 ! lat] rock4 ,! y\ng] sill disappe>s to ! nor?1 & is n f\nd 9 ! cliff ( ,rudha ,*rn nan ,ce>c1 :]e ! ?ick sill1 ly+ once m on ! b& ( conglom]ate1 =ms a f9e esc>pm5t above ! %ore4 ,dykes ( f9e-gra9$ basalt 7d d7 ) compact *ill$ m>g9s rise ?r\gh bo? sills1 toge!r ) ve9s :i* pursue a wavy upw>d pa? l /rips ( black ribbon4 ,?is example1 & t ( ! ,%iant ,isles already describ$1 _c b impress ! obs]v] ) ! prodigi\s =ce ) :i* ! mat]ial ( ! sills 0 inject$4 ,9 ^! in/ances solid %eets ( intrusive rock h subsequ5tly be5 r5t op51 d\btless "u a sup]9cumb5t pressure ( _m hundr$s ( feet ( ! t]re/rial cru/1 & a new injection ( molt5 magma has made its way into ! r5ts ?us caus$4 ,9 ea* case1 ! position ( ! r5ts 0 obvi\sly det]m9$ by /ructural l9es 9 ! old] sills1 b we are lo/ 9 a/oni%m5t at ! en]gy requir$ to split op51 ev5 along ^! l9es1 su* solid cry/all9e masses z ! ?ick sills1 & to ov]come ! sup]9cumb5t pressure ( s deep a pile ( rock4 ,! isolation ( a relic ( ! ,t]ti>y sills on ! we/ side ( ! promontory ( ,sleat pres5ts "s int]e/+ problems to ! m9d ( ! geologi/4 ,! locality lies ab\t midway betwe5 ! basalt-plateau ( ,/ra?aird & t ( ,eigg1 & "s eight or n9e miles 9 a direct l9e f ei!r4 ,! basalts _c be prov$ to h once /ret*$ cont9u\sly betwe5 ,eigg & ,/ra?aird1 & to h cov]$ ?is "p ( ,sleat2 b ! position ( ! ,sleat sills makes x probable t ?is cont9uation did =m]ly exi/4 ,! d5udation ( ! ,we/ ( ,scotl& s9ce e>ly ,t]ti>y "t has be5 s /up5d\s t ,i am prep>$ = almo/ any seem+ly incr$ible evid5ce ( its effects4 ,!re c h>dly be any d\bt1 h[ev]1 t ! sills "h describ$ belong to ! great plat=m ( intrusive %eets1 & t !y 7 inject$ "u a pile ( ,second>y /rata1 if n also ( ,t]ti>y basalts1 :i* has "h be5 entirely remov$4 ,ref]5ce may be made1 9 conclusion1 to a n infrequ5t feature ( ! ,skye sills4 ,l ! dykes1 !y are (t5 d\ble or multiple1 molt5 mat]ial hav+ be5 successively inject$ along ! same plane4 ,! example j cit$ f ! we/ side ( ,sleat illu/rates "o type ( su* comp\nd sills4 ,m frequ5tly1 h[ev]1 ! subsequ5t injections h be5 made along ! floor or ro( ( ! fir/ %eet4 ,mr4 ,h>k] has f\nd num]\s cases ( ?is /ructure 9 ! ,/ra? di/rict4 ,!y are recognizable ev5 f a di/ance by _! t]rac$ cont\rs :5 se5 9 pr(ile4 ,!y (t5 v>y consid]ably 9 ?ickness ow+ to ! dy+ out or com+-9 ( _! sep>ate b&s2 :ile1 on ! o!r h&1 s+le sills t5d to ma9ta9 a uni=m ?ickness = long di/ances1 or tap] away gradually4 ,! comp\nd arrangem5t ( ! basic sills is well br\ght out :]e acid mat]ial has be5 inject$ betwe5 ! %eets1 z w be m fully describ$ 9 ,*apt] xlviii4 iii4 ,,eigg1 ,,ardnamur*an ,! ph5om5a ( ! coa/s ( ,skye are repeat$ on ! ea/ side ( ,raasay1 9 ,eigg1 & /ill m magnific5tly along ! s\? coa/ ( ,mull4 ,a s+le example is "h giv5 7,fig4 #cbe7 f ! ea/ side ( ,eigg4 ,ov] ! ,jurassic s&/ones 7a a7 a sill ( basalt 7#a7 f\r to six feet ?ick has be5 inject$ betwe5 ! /ratification1 & ano!r 7#b7 two to f\r feet ?ick has =c$ its way across ! middle ( "o ( ! b$d$ basalts 7b b7 9 :i* x bifurcates1 & above :i* comes ! ?ick s]ies ( lavas ( ! plateau 7c1 d74 ,9 "o ( ! /reamlets1 :i* exposes a section ( ! ,jurassic /rata bel[ ! volcanic esc>pm5t1 m ?an tw5ty intrusive %eets may be c\nt$ among ! %ales & lime/ones4 ,!y are sometimes n six in*es ?ick1 & seldom exce$ six or eight feet4 ,illu/ration3 ,fig4 #cbe4--,section to %[ ,b$d$ & ,intrusive ,%eets1 ,eigg4 ,i w conclude ?is acc\nt ( ! ,t]ti>y basic sills ( ,brita9 by ref]r+ to "o fur!r di/rict 9 ! ,we/ ( ,scotl&1 :]e !y are well display$ on b>e hillslopes & also along a picturesque sea-coa/4 ,9 ! promontory ( ,ardnamur*an 9 ! we/ ( ,argyle%ire1 "o ( ! mo/ conspicu\s em95ces1 kn[n z ,b5 ,hiant1 af=ds a /rik+ mass ( intrusive mat]ial1 :i*1 ext5d+ along a rugg$ %ore = ?ree-qu>t]s ( a mile1 m\nts !nce inl& 9 a s]ies ( rocky knolls1 & 9 r less ?an a mile culm9ates 9 a summit1 #agbi feet above sea-level4#cbj ,! rocks :i* cov] ?is l>ge space are dispos$ 9 num]\s rude b$s1 :i* h a seaw>d dip ( p]haps #ae to #bj1 & are sometimes di/9ctly prismatic1 ! prisms be+ n infrequ5tly gr\p$ 9 fan-%ape4 ,!y are evid5tly due to successive intrusions4 ,al?\gh g5]ally co>sely cry/all9e 9 texture1 !y include also int]m$iate & f9e-gra9$ %eets4 ,!y are nev]1 s f> z ,i h be5 able to discov]1 amygdaloidal1#cba nor d !y pres5t ! ord9>y ext]nal *>act]s ( ! b$s ( ! plateaux1 ?\gh "h & !re !y appe> to h caught up portions ( ! plateau-s]ies4 ,!y di/9ctly ov]lie ! b$d$ basalts on _! ea/]n & s\!rn m>g9s2 b we/w>ds !y appe> to lie transgressively across ! edges ( ^! rocks1 :ile to ! nor?-we/ & nor? !y re/ on qu>tzites & s*i/s & on ,jurassic lime/ones4 ,an outli] f ! ma9 mass =ms ! prom95t hill ( ,srn ,mhor1 & c be se5 di/9ctly ov]ly+ ! b$d$ basalts z well z ! neck ( agglom]ate already describ$ 7,fig4 #cjb74 ,footnote #cbj3 ,?is locality has be5 describ$ by ,pr(essor ,judd 7,qu>t4 ,j\r4 ,geol4 ,soc4 xxx4 7#ahgd71 p4 #bfa2 & xlvi4 7#ahij71 p4 #cgc74 ,footnote #cba3 ,z amygdaloidal /ructure is occasionally to be f\nd among bo? dykes & sills its pres5ce 9 ! ,b5 ,hiant rocks w\ld n be inconsi/5t ) _! intrusive orig94 ,! preval5t rocks ( ,b5 ,hiant are well cry/alliz$1 ophitic oliv9e-dol]ites & gabbros4 ,a specim5 tak5 f ! %ore on ! we/ side ( ! mass 0 f\nd by ,dr4 ,hat* to pres5t "u ! microscope its augite 9 l>ge plates1 :i* enclose n>r[ la?s & ne$les ( plagioclase felsp> z well z gra9s ( oliv9e4 ,all ! felsp>s are 9 la?-%apes1 sometimes extremely long & n>r[4 ,! iron-ore likewise assumes an ophitic "*1 enclos+ rectangul> portions ( felsp>4 ,dr4 ,hat* obs]v$ 9 ano!r specim51 tak5 f ! s\?-ea/ side ( ! hill1 a curi\s int]mixture ( two diff]5t /ructures4 ,scatt]$ portions :i* %[ ! usual ophitic /ructure1 _! felsp> & augite occurr+ 9 l>ge cry/als1 are1 s to speak1 imb$d$ 9 a gr\ndmass :i* pres5ts r a basaltic type1 its felsp>1 augite1 & magnetite1 9 long ?9 ne$les1 microlites1 & o!r skeleton =ms1 be+ enclos$ 9 a d>k devitrifi$ base4 ,a ?ird specim51 select$ f "o ( ! column> %eets ne> ! top ( ,b5 ,hiant1 is a f9e-gra9$ dol]ite 7or gabbro7 %[+ little ophitic /ructure1 ! augite occurr+ 9 r\ndi% gra9s1 & only slightly int]gr[n ) ! felsp>s1 :i* are m or less la?-%ap$4 ,! rock conta9s a consid]able quantity ( black iron-ore 9 irregul> gra9s & "s dirty-gre5 viridite4 ,/ill ano!r v>iety ( /ructure occurs 9 a specim5 :i* ,i broke f "o ( ! %ore crags on ! s\?-we/ side ( ! hill4 ,"u ! microscope1 ,dr4 ,hat* f\nd 9 x a beautiful aggregate ( skeleton cry/als & microlites ( plagioclase1 ) "h & !re a rectangul> cry/al1 long sl5d] microlites ( augite1 & %ort s]rat$ microlites ( magnetite1 ! :ole be+ confus$ly imb$d$ 9 a d>k glassy base p[d]$ ov] ) a f9e magnetite du/4#cbb ,a sill ( pit*/one lies among ! b$d$ basalts on ! ea/ side ( ! hill4 ,footnote #cbb3 ,pr(essor ,judd has call$ ! rocks ( ,be9n ,hiant augite-&esites1 & has giv5 descriptions & figures ( _! /ructure1 & analyses ( _! *emical composition 7op4 cit474 ,f a numb] ( specim5s collect$ by me dur+ a second visit to ?is di/rict 9 ! summ] ( #ahif1 ,i select$ "s = microscopic exam9ation & submitt$ !m to ,mr4 ,h>k]1 :o has furni%$ me ) ! foll[+ descriptions ( !m3 ,! sill at ! nor? end ( ,camas na ,cloi*e1 ,b5 ,hiant #gaad is an oliv9e-gabbro ( m$ium gra9 & fre% appe>ance4 ,oliv9e1 fre% or p>tly s]p5t9iz$1 is pl5tiful4 ,! felsp> is a labradorite ) ,c>lsbad- & albite- 7r>ely p]icl9e-7 tw9n+1 & "s ( x has zon>y b&+4 ,x is = ! mo/ "p 9 cry/als giv+ rectangul> sections1 b !re are "s ( allotriomorphic =m4 ,magnetite occurs *iefly 9 %apeless gra9s ( lat] cry/allization ?an ! felsp>1 b sometimes pres5t+ cry/al-faces to ! augite4 ,! augite is light-br[n 9 ! slice1 )\t any true diallage-/ructure1 & t5ds to enwrap ! e>li] m9]als 9 ophitic pat*es4 ,! sill s\? ( ,uamh na ,creadha1 on ! we/ side ( ,b5 ,hiant #gaae1 is a rock ( diff]5t type1 hav+ porphyritic cry/als ( felsp>1 up to an in* or m 9 l5g?1 9 a r f9ely-cry/all9e gr\ndmass4 ,! microscope %[s x to be a dol]ite ( granulitic /ructure1 ! ma9 mass ( ! rock consi/+ ( little /riat$ labradorite-cry/als1 gra9s ( pyrox5e1 & r abundant cry/al-gra9s ( magnetite4 ,! pyrox5e seems to be *iefly augite1 b hyp]/h5e is also pres5t1 & builds r l>g] & m idiomorphic cry/als ) *>act]i/ic pleo*roism4 ,9 rambl+ ov] ?is ,ardnamur*an di/rict ,i h (t5 be5 rem9d$ ( ! great intrusive %eets ( ,fair ,head4 ,"o ( ! features 9 :i* ! rocks ( ! two localities resemble ea* o!r is _! t5d5cy to assume a co>sely cry/all9e texture4 ,9 "s p>ts ( ,b5 ,hiant ! individual cry/als rea* an in* or m 9 l5g?4 ,^! m l>gely cry/all9e portions1 h[ev]1 d n =m di/9ct b&s s mu* z pat*es 9 ! mid/ ( ! g5]al mass2 at lea/ ,i h n notic$ any examples ( su* ve9s ( segregation z are s prom95t 9 ,antrim4 ,no "o famili> ) ! well-m>k$ di/9ctions betwe5 ! lavas ( ! plateaux & ! sills :i* trav]se !m c hesitate 9 :i* s]ies to place ! rocks ( ,b5 ,hiant4 ,s9ce1 h[ev]1 ^! rocks h be5 claim$ by ,pr(essor ,judd z ! sup]ficial lava-curr5ts ( a volcano :i* broke out aft] ! "t ( ! plateau-basalts1 l ! ,scuir ( ,eigg1 "s fur!r details 9 reg>d to ! geological /ructure ( ! di/rict1 :i* w\ld o!rwise be sup]flu\s1 may "h be giv54 ,! numb] ( sills & dykes 9 ,ardnamur*an is a/oni%+ly great4 ,!re mu/ be hundr$s ( !m visible1 & p]haps z _m m conceal$ "u sup]ficial cov]+s4 ,!y are well expos$ on ! %ore trav]s+ ! ,jurassic /rata & ! s*i/s4 ,! sills become especially l>ge & abundant 9 ! direction ( ,b5 ,hiant1 :i* has evid5tly be5 ! pr9cipal c5tre f :i* _! mat]ials 7 inject$4 ,! rocks compos+ ^! sills are q simil> to ^? ( ,b5 ,hiant1 save t1 z !y occur 9 ?9n] %eets ?an 9 t m\nta91 !y d n atta9 ! same co>s5ess ( texture :i* ! m massive b$s !re display4 ,!y g5]ally possess f9e-gra9$ *ill$ selvages along _! upp] & "u surfaces4 ,illu/ration3 ,fig4 #cbf4--;,gr\nd-plan ( ,sills at ,b5 ,hiant1 ,ardnamur*an4 a a1 cry/all9e s*i/s2 b b1 necks ( volcanic agglom]ate2 c c1 num]\s ?9 sills2 ,d1 massive sill ( ,be9n na h-,ur*ra*2 ,e1 nor? side ( ,b5 ,hiant2 ,f1 sill proce$+ f ! s]ies =m+ ,b5 ,hiant & jo9+ t ( ,be9n na h-,ur*ra*4 ,! arr[s m>k ! dip4 ,^! abundant sills may be trac$ up into ! mass ( ,b5 ,hiant f :i* !y h issu$1 & ( ! individual %eets ( :i* !y are a cont9uation4 ,"o ( ! mo/ /rik+ & easily-foll[$ examples ( ?is connection is to be se5 on ! nor? side ( ! m\nta94 ,a ?ick %eet 9 ! middle ( ,b5 ,hiant desc5ds f among its contigu\s %eets &1 z a prom95t rib1 runs d[n ! scree-slope into ! valley bel[1 :]e x =ms a prom95t feature4 ,cross+ ! /reamlet 9 ! middle ( ! valley1 :]e a section has be5 cut ?r\gh its upp] surface1 x gradually b5ds r\nd t[>ds ! nor?-ea/1 m\nts ! side ( ,be9n na h-,ur*ra* until x rea*es ! cre/ ( ! ridge & jo9s ! o!r sills ( :i* ?is em95ce is built up4 ,! r\te ( ?is b& ( rock w be und]/ood f ! annex$ gr\nd-plan 7,fig4 #cbf74 ,t ?is prolongation ( "o ( ! ?ick b$s ( ,b5 ,hiant is 9 no respect a sup]ficial lava-/ream b a true sill1 is prov$ n only by its esc>pm5t & dip-slope1 b by its actually pass+ "u & indurat+ ! s*i/ose grits1 z may be se5 9 ! /ream-section4 ,aga9 ,be9n na h-,ur*ra*1 :i* is mapp$ by ,pr(essor ,judd z a nor!rn expansion ( ,b5 ,hiant1 is likewise n a lava b a true sill4 ,n only does x dip nor?w>ds at an angle ( ab\t #bj1 hav+ ! s*i/s imm$iately bel[ its cre/ on ! "o side & desc5d+ ) a long dip-slope on ! o!r1 b dw9dl+ d[n rapidly f a ?ickness ( #ajj or #bjj feet 9 ! c5tre to no m ?an a few feet 9 a s\?-we/]ly direction1 x !re passes "u s*i/ose grits l ^? on :i* x lies4 ,! /rata t adh]e to its upp] surface are z usual indurat$4 ,a section drawn across ?is att5uat$ developm5t ( ! ,be9n na h-,ur*ra* sill & t f ,b5 ,hiant %[s ! /ructure repres5t$ 9 ! accompany+ diagram 7,fig4 #cbg71 :i* simply gives ! facts z expos$ on ! gr\nd4 ,! l[] sill is t :i* issues f ! ma9 body ( ,b5 ,hiant1 massive at fir/ b dim9i%+ 9 ?ickness z x rec$es f its s\rce4 ,aga91 among ! %eets :i* desc5d f ! nor!rn face ( ! summit ( ,b5 ,hiant & /rike into ! ,jurassic outli] bel[1 int5sely indurat$ %ale may be se5 ly+ betwe5 two ( ! dol]ites1 :i* are unque/ionably sills t h be5 inject$ into ! ,jurassic s]ies4 ,! ridge ( ,b5 ,hiant is ?us f\nd to consi/ ( a ?ick & complex s]ies ( sills1 "s ( :i* are n traceable beyond ! side ( ! m\nta91 :ile o!rs c be foll[$ outw>ds among ! surr\nd+ rocks4 ,! specially m>k$ dyke-l sills div]ge f ! ma9 mass & run = "s di/ance nor?-ea/w>d1 "o ( !m1 fully a mile long1 desc5d+ among ! s*i/s into ! valley & asc5d+ into ! basalt-plateau on ! opposite side4#cbc ,footnote #cbc3 ,! sills ( ,b5 ,hiant desc5d on ! s\?-we/ side into ! sea1 & c be exam9$ along ! slopes & ! bea*1 :]e ,pr(essor ,judd has mapp$ a cont9u\s plat=m ( agglom]ate4 ,! broad holl[ betwe5 t m\nta9 & ,be9n na h-,ur*ra*1 ov] :i* he has spread 8 augite-&esite lavas1 appe>s to be und]la9 ma9ly by ! cry/all9e s*i/s ?r\gh :i* sills f ,b5 ,hiant h be5 inject$4 ,! nor!rn em95ce1 :i* he has unit$ ) ,b5 ,hiant1 is entirely sep>ate &1 z above %[n1 is an obvi\s sill4 ,illu/ration3 ,fig4 #cbg4--,section ( two ,sills 9 s*i/ose grits1 we/ end ( ,be9n na h-,ur*ra*1 ,ardnamur*an4 a a1 cry/all9e s*i/s2 b1 neck ( volcanic agglom]ate2 c1 small sill2 ,d1 massive sill ( ,be9n na h-,ur*ra*2 ,f1 sill proce$+ f ! s]ies =m+ ,b5 ,hiant & jo9+ t ( ,be9n na h-,ur*ra*4 ,on ! s\?-ea/ side ( ! m\nta9 :]e ! b$d$ basalts c be trac$ close up to ! intrusive dol]ites1 !y are f\nd to pres5t ! usual dull indurat$ aspect s *>act]i/ic ( contact alt]ation among ^! rocks4 ,!re _c !re=e be any d\bt t ,b5 ,hiant nev] 0 itself a volcano4 ,its rocks are *>act]i/ically ^? ( subt]ranean intrusions4 ,!y seem to h be5 inject$ f a l9e ( fissure or f sev]al su* l9es1 runn+ 9 a g5]al nor?-ea/]ly direction1 at "s late "p ( ! volcanic p]iod4 ,! gr\p ( agglom]ate necks ( old] date %[s t already ! gr\nd und]nea? _h be5 drill$ by a numb] ( di/9ct volcanic funnels1 & discloses a weak "p 9 ! t]re/rial cru/4 iv4 ,,f>oe ,,isles ,9 ! ,f>oe ,isl&s ! actual base ( ! volcanic s]ies is n[h]e visible4 ,h5ce1 ! great l[] plat=m ( intrusive %eets be+ !re conceal$1 ?is feature ( ! basalt-plateaux is less conspicu\s ?an x is 9 ! ,inn] ,hebrides4 ,a numb] ( sills1 h[ev]1 h be5 notic$ by previ\s obs]v]s1#cbd & ,i h obs]v$ o!rs on ! sides ( ,/rom1 ,kals1 ,kun & o!r isl&s4 ,9 ! l(ty precipices ( ! ,h>aldsfjord1 _m ( ! massive light-col\r$ prismatic %eets are intrusive1 = ?\gh !y pres]ve _! p>allelism ) ! b$d$ %eets = consid]able di/ances1 !y may be se5 sometimes to break across ^!1 z is /rik+ly %[n 9 "o ( ! great corries on ! ea/ side ( ,kun4 ,footnote #cbd3 ,see 9 p>ticul> ,pr(4 ,james ,geikie & ,mr4 ,lomas1 9 ! pap]s already cit$ on p4 #aia4 ,illu/ration3 ,fig4 #cbh4--,sill trav]s+ b$d$ ,basalts1 cliffs ( ,/rom1 at entrance ( ,vaagfjord4 ,! caves & not*es %[n at ! bottom ( ! precipice m>k ! position ( ! v5ts repres5t$ 9 ,figs4 #caa1 #cab1 #cac1 #cad4 ,"o ( ! mo/ rem>kable sills 9 ! ,f>oe ,isl&s is probably t :i* =ms s prom95t an object on ! we/]n cliffs ( ,/rom1 at ! entrance into ! ,vaagfjord 7,figs4 #cbh1 #cbi74 ,x is prismatic 9 /ructure1 & :]e x runs along ! face ( ! cliffs1 p>allel to ! b$d$ basalts among :i* x has be5 intrud$1 pres5ts ! famili> *>act]s ( su* %eets4 ,! precipice ( :i* x =ms a "p is t :i* rises above ! r[ ( volcanic v5ts already describ$4 ,b x !re beg9s to asc5d ! cliffs obliquely across ! basalts until x rea*es ! cre/ ( ! great wall ( volcanic rock at a height ( probably ab\t #ajjj feet above ! waves4 ,f ! cre/ ( ! precipice ! upw>d c\rse ( ! sill is cont9u$ into ! int]ior ( ! isl&4 ,x pursues its way z a l9e ( bold crag along ! ridges ( ! plateau1 gradually asc5d+ till x =ms ! summit ( "o ( ! mo/ prom95t hills 9 ! di/rict 7,fig4 #cbi74 ,"s fur!r idea ( ! enorm\s en]gy ) :i* ! sills 7 inject$ may be =m$ f ?is example1 :]e ! eruptive mat]ials foll[$ nei!r ! l9e ( b$d+ nor a v]tical fissure1 b took an oblique c\rse ?r\gh ! plateau-basalts = a v]tical di/ance ( probably m ?an #aejj feet4 ,v4 ,,g5]al ,,d$uctions ,,reg>d+ ,,! ,,t]ti>y ,,basic ,,sills ,if we consid] ! facts :i* h n[ be5 adduc$ reg>d+ ! position & /ructure ( ! sills1 we are l$1 ,i ?9k1 to reg>d ^! masses z c]ta9ly belong+ to ! hi/ory ( ! basalt-plateaux1 b1 on ! :ole1 to a comp>atively late "p ( x4 ,!y consi/ ( ess5tially ! same mat]ials z ! lavas t =m ^! plateaux1 ?\gh ) ! diff]5ces ( /ructure :i* ! conditions ( _! production w\ld lead u naturally to expect4 ,:]e !y occur 9 ?ick masses1 :i* mu/ obvi\sly h cool$ mu* m sl[ly at "s dep? b5ea? ! surface ?an ! comp>atively ?9 %eets c\ld d t 7 p\r$ out above gr\nd1 !y h assum$ a f> m l>gely cry/all9e texture ?an t ( ! sup]ficial lavas4 ,z a rule1 we may say t ! ?ick] ! sill ! co>s] is its texture1 :ile ! ?9ne/ %eets are ! mo/ close-gra9$4 ,sills are especially abundant ab\t ! base ( ! basaltic-plateaux4 ,we may exam9e miles ( ! c5tral & high] p>ts ( ! esc>pm5ts )\t detect+ a s+le example ( !m1 b if ! esc>pm5t is cut d[n to ! base we seldom ne$ to se>* f> to f9d !m4 ,illu/ration3 ,fig4 #cbi4--,view ( ! same ,sill se5 f ! *annel opposite ! isl& ( ,kolt]4 ,t ! ef=ts ( ! int]nal magma to e/abli% an outlet t[>ds ! surface 7 accompani$ by p[]ful di/urbances ( ! t]re/rial cru/ is %[n by ! abundant dykes :i* trav]se all ! volcanic di/ricts f ,antrim to ,icel&1 & "s ( :i* asc5d ev5 to ! v highe/ rema9+ lavas ( ! basalt-plateaux4 ,! p>allel fissures fill$ by ^! dykes prove t ev5 aft] ! accumulation ( m ?an #cjjj feet ( basalt-%eets1 ! movem5ts cont9u$ to be s p[]ful z to disrupt ^! va/ piles ( volcanic mat]ial4 ,b und\bt$ly ! highe/ p>ts ( ! plateau-basalts are less cut by dykes ?an ! l[] p>ts4 ,!re w\ld no d\bt come a "t :5 ! dislocations w\ld m seldom rea* ! surface1 :5 dykes w\ld n be =m$ s abundantly or up to su* a high level1 & :5 ! volcanic en]gies w\ld m & m sp>+ly result 9 ! op5+ ( new v5ts or 9 ! dis*>ge ( fre% eruptions f old ones4 ,x appe>s to me mo/ probable t ! injection ( ! sills 0 connect$ ) ! same t]re/rial di/urbances t produc$ ! dykes :i* trav]se ! plateaux4 ,besides be+ dislocat$ by p>allel fissures1 ! e>?'s cru/ 9 ,nor?-,we/]n ,europe seems to h be5 ruptur$ int]nally along l9es m or less at "r angles to ! v]tical fissures4 ,! deep accumulation ( b$d$ basalts pres5t$ an increas+ ob/acle to ! asc5t ( ! magma to ! surface4 ,unable to ga9 ample en\gh egress ?r\gh su* v]tical fissures z might be =m$ 9 ! volcanic pile1 ! molt5 rock w\ld f9d its l9es ( lea/ resi/ance along ! planes ( ! /rata & ! l[] basalt-b$s1 ei!r by ! aid ( t]re/rial ruptures !re1 or 9 virtue ( its own en]gy4 ,on ^! horizons1 accord+ly1 ! sills occur 9 extraord9>y pr(usion ?r\gh\t ! volcanic regions4 ,!y are no d\bt ( all ages 9 ! progress ( ! build+ up ( ! volcanic plateaux1 b ,i am dispos$ to believe t a l>ge numb] ( !m may belong to ! v late/ p]iod ( ! uprise ( basalt )9 ! area ( ,brita94 ,"o ( ! mo/ sugge/ive features ( ! abundant ,t]ti>y sills lies 9 ! evid5ce !y furni% ( ! enorm\s en]gy conc]n$ 9 ! asc5t & intrusion ( volcanic mat]ial4 ,! infill+ ( dykes or ! outp\r+ ( successive /reams ( lava at ! surface h>dly appeals to our imag9ation s /rik+ly z ! pro( t ! sills h be5 impell$ into _! places ) a vig\r :i*1 ev5 :5 guid$ & aid$ by gigantic t]re/rial ruptures1 0 capable ( ov]com+ ! v]tical pressure ( hundr$s1 or ev5 ?\s&s ( feet ( ov]ly+ rock4 ,_h ^! intrusive %eets be5 m]e ?9 lay]s1 _! horizontal ext5t & p]si/5ce w\ld /ill h excit$ our a/oni%m5t1 b :5 we f9d !m sometimes sev]al hundr$ feet ?ick1 & to ext5d 9 a cont9u\s s]ies = horizontal di/ances ( #ej miles or m1 we are lo/ 9 wond] at ! prodigi\s expansive /r5g? ( ! volcanic =ces4 ,aga91 ! intrusions h n always tak5 place betwe5 ! b$d+-planes ( ! /ratifi$ or igne\s rocks1 b1 z we h se51 solid %eets ( already deeply buri$ lavas h sometimes be5 split op5 & ! intrusive mat]ial has =c$ itself betwe5 ! disrupt$ portions4 ,su* subt]ranean pro(s ( ! vig\r ( volcanic en]gy tea* "s ( ! mo/ impressive lessons 9 ! *ronicles ( volcanic action 9 ! ,briti% ,isles4 99 99 99 99 99 ,9 clos+ ?is hi/ory ( ! accumulation ( ! great ,t]ti>y volcanic plateaux ( ,nor?-,we/]n ,europe1 ,i w\ld rem>k t z ! result ( prolong$ eruptions f innum]able v5ts1 ! depression t ext5d$ f ! s\? ( ,antrim to ! ,m9* 0 gradually fill$ up ) successive %eets ( basalt to a dep? ( m ?an #cjjj feet4 ,a succession ( lava-fields /ret*$ f ! ,nor? ( ,irel& across ! ,we/ ( ,scotl&1 & p]haps ev5 to ! ,f>oe ,isl&s1 ,icel& & ,gre5l&4 ,t ! lava spread r\nd ! base ( ! ,highl& m\nta9s & ran up ! ,highl& gl5s1 mu* z ! sea n[ does1 is made cle> f ! position ( ! outli]s ( x :i* h be5 left p]*$ on ! ridges ( ,morv5 & ,ardnamur*an4 ,s f> z c n[ be surmis$1 ^! wide ,phlegran fields 7 only v>i$ by occasional volcanic cones scatt]$ ov] _! surface1 m>k+ "s ( ! la/ v5ts f :i* /reams ( basalt _h fl[$4 ,b ! volcanic en]gy 0 /ill f> f exhau/ion4 ,aft] ! accumulation ( su* a deep & f>-ext5d$ %eet ( lava1 ^? und]gr\nd movem5ts :i* produc$ ! fissures t s]v$ z *annels = ! uprise ( ! e>lie/ dykes cont9u$ to %[ _! vig\r4 ,! pile ( b$d$ lavas 0 r5t op5 by innum]able long p>allel fissures 9 ! preval5t nor?-we/]ly direction1 up :i* basic lavas rose to =m dykes1 :ile va/ numb]s ( sills 7 inject$ und]nea?4 ,:e!r ! outfl[ ( basalt at ! surface _h :olly ceas$ :5 ! la/ ( ^! dykes 7 inject$ into ! plateaux _c be told4 ,nor is !re any evid5ce :e!r x _h end$ be=e ! next great episode ( ! volcanic hi/ory--! extravasation ( ! gabbro bosses4 ,all t we c affirm ) c]ta9ty is1 t ! =mation ( nor?-we/ fissures & ! uprise ( basalt 9 !m 7 aga9 repeat$1 = we f9d nor?-we/ dykes trav]s+ ev5 ! cre/s ( ! lat] eruptive masses ( basic & acid rocks4 ,x is difficult to suppose t none ( ^! late/ dykes communicat$ ) ! surface1 & gave rise to cones ) ! outp\r+ ( basalt & ! ejection ( du/ & /ones4 ,b ( su* lat] outfl[s ( basic mat]ial ov] ! surface ( ! plateaux no und\bt$ trace has yet be5 recognis$4 ,,*apt] ,,xliii ,,! ,,bosses ,,& ,,%eets ,,( ,,gabbro ,petrography ( ! ,rocks--,relations ( ! ,gabbros to ! o!r memb]s ( ! ,volcanic s]ies--,description ( ! ,gabbro di/ricts--,skye ,9 s+ul> contra/ to ! ne>ly flat basalts ( ! plateaux1 ano!r s]ies ( rocks rises high & abruptly above ^! tablel&s into gr\ps ( dome-%ap$1 conical1 spiry1 & rugg$ hills4 ,x is ^! heights :i*1 m ?an any o!r feature1 relieve ! monotony ( ! wide areas ( almo/ horizontal /ratification s *>act]i/ic ( ! volcanic region ( ! nor?-we/4 ,_! geological /ructure & hi/ory are mu* less obvi\s ?an ^? ( ! b$d$ basalts4 ,_! m\nta9\s =ms at once sugge/ a :olly diff]5t orig94 ,"s portions ( !m h ev5 be5 comp>$ ) ! olde/ or ,ar*an rocks4#cbe ,t !y are really portions ( ! ,t]ti>y volcanic s]ies1 & t !y reveal a :olly di/9ct phase 9 ! hi/ory ( volcanic action1 is n[ frankly admitt$4 ,:e!r we reg>d !m f ! petrographical or /ructural po9t ( view1 !y naturally arrange !mselves into two well-def9$ gr\ps4 ,( ^! "o consi/s ( highly basic comp\nds1 ( :i* oliv9e-gabbro is ! mo/ prom95t4 ,! o!r comprises num]\s v>ieties--granite1 granophyre1 felsite1 qu>tz-porphyry1 pit*/one & o!rs--all ( !m be+ m or less decid$ly acid1 & "s ( !m m>k$ly s4 ,= reasons :i* w appe> 9 ! sequel1 ! =m] gr\p mu/ be consid]$ z ! old] ( ! two1 & x w !re=e be describ$ fir/4 ,footnote #cbe3 ,?is 0 my own fir/ impression1 :5 ,i began1 z a boy1 to ramble among !m4 ,! rem>kable resemblance ( "s p>ts ( !m to anci5t gneisses w be aft]w>ds dwelt ^u4 ,maccullo* _h correctly gr\p$ !m ) ! o!r ov]ly+ rocks1 & ?is conclusion 0 aft]w>ds confirm$ by ,pr(4 ,zirkel4 i4 ,,petrography ,,( ,,! ,,gabbro ,,areas ,s9ce ! publications ( ,maccullo*1 ! occurr5ce ( beautiful v>ieties ( highly basic rocks among ! igne\s masses ( ! ,we/]n ,isles has be5 famili> to geologi/s4 ,!y 7 nam$ by him hyp]/h5e rock & augite rock1#cbf names :i* cont9u$ 9 use until #ahga1 :5 my fri5d ,pr(essor ,zirkel publi%$ ! results ( 8 t\r ?r\gh ! ,we/ ( ,scotl&1 & %[$ t ! rocks 9 "q 7 mo/ly true gabbros4#cbg ,s9ce 8 obs]vations 7 publi%$ "s ( ^! rocks h =m$ ! subject ( important pap]s by ,pr(essor ,judd4#cbh ,footnote #cbf3 ,we/]n ,isl&s1 vol4 i4 pp4 #che1 #dhd4 ,footnote #cbg3 ,zeits*rift4 ,deuts*4 ,geol4 ,gesells*4 xxiii4 7#ahga71 p4 #a4 ,footnote #cbh3 ,qu>t4 ,j\r4 ,geol4 ,soc4 xli4 7#ahhe71 p4 #ced2 xlii4 7#ahhf71 p4 #di4 ,! g5]al petrographical *>act]s ( ! gabbro areas ( ,we/]n ,scotl& may be summ>iz$ z foll[s3--,a v consid]able v>iety ( petrological /ructure & *emical composition is obs]vable among ! rocks4 ,at ! "o end ( ! s]ies are comp\nds ( plagioclase & augite1 :i*1 ?\gh want+ 9 oliv9e1 h ! g5]al /ructure & habit ( dol]ites4 ,at ! o!r end are mixtures :]e9 felsp> is sc>ce or abs5t1 & :]e oliv9e becomes ! *ief con/itu5t4 ,betwe5 ^! two extremes are _m int]m$iate grades1 ( :i* ! mo/ important are ^? conta9+ ! v>iety ( augite kn[n z diallage & also oliv9e4 ,^! are ! oliv9e-gabbros1 :i* =m s m>k$ a feature 9 ! c5tral p>ts ( ! great basic bosses4 ,t "s ( ^! v>ieties ( rock pass into ea* o!r _c be d\bt$4 ,_! di/9ctive composition & /ructure appe> to h be5 l>gely det]m9$ by _! position 9 ! eruptive mass4 ,! out] & ?9n] %eets are 9 great measure dol]ites1 ) little or no oliv9e4 ,co>se gabbros are abundant 9 ! inn] portions4 ,rocks ri* 9 oliv9e1 h[ev]1 occur at ! out] & especially ! l[] "p ( ! gabbro masses ( ,rum & 9 "s p>ts ( ,skye4 ,! foll[+ lead+ v>ieties may be enum]at$3-- ,dol]ite4--,?is rock v>ies f an exce$+ly close gra9 7:5 x approa*es & graduates into basalt7 up to a co>se granul> cry/all9e texture1 9 :i* ! compon5t m9]als are di/9ctly visible to ! nak$ eye4 ,an av]age sample is f\nd to consi/ ( plagioclase1 usually la?-%ap$1 & cry/als or gra9s ( augite ) or )\t oliv9e4 ,"u ! microscope1 ! diff]5t v>ieties are di/+ui%$ by ! pres5ce ( m or less di/9ct ophitic /ructure1 ! felsp> be+ envelop$ 9 ! augite4 ,= ! mo/ "p !y are holocry/all9e1 b occasionally %[ traces ( a glassy base4 ,ilm5ite is n infrequ5t1 ) its *>act]i/ic turbid decomposition product 7leucox5e74 ,9 o!r cases1 ! iron-ore is probably magnetite4 ,betwe5 ! dol]ites & gabbros no l9e ( dem>cation c be drawn 9 ! field1 nor c a mu* m satisfactory limitation be made ev5 ) ! aid ( ! microscope4 ,z a rule1 ! ?icke/ & l>ge/ intrusive masses or bosses are gabbro1 ^? ( less size are dol]ite1 :ile ! smalle/ 7& sometimes ! edges ( ! o!rs7 assume ext]nally ! aspect ( basalts4 ,gabbro4--,"u ?is t]m ,i arrange1 z propos$ by ,pr(essor ,judd1 all ! co>se-gra9$ granitoid basic rocks ( ! region )\t ref]5ce to ! v>iety ( augite pres5t 9 !m4 ,"u ! microscope1 !y are f\nd to be holocry/all9e1 b ) a granitic or granulitic r ?an an ophitic /ructure1 ?\gh traces ( ! latt] are by no means r>e4 ,to ! nak$ eye _! compon5t m9]als are usually recognizable4 ,pr(essor ,zirkel1 f 8 exam9ation ( ! ,mull gabbros1 believ$ !m to consi/ ( ?ree p>ts ( plagioclase1 two p>ts ( oliv9e1 & "o "p ( diallage4#cbi ,oliv9e1 h[ev]1 is n inv>iably pres5t4#ccj ,! pyrox5e also does n always %[ ! peculi> fibr\s /ructure ( diallage4 ,pr(essor ,judd1 inde$1 ma9ta9s t ! diallagic =m is due to a deep-seat$ process ( alt]ation 7s*ill]ization71 & t ! same cry/al may consi/ p>tly ( ord9>y augite & p>tly ( diallage4#cca ,ilm5ite 7) leucox5e71 magnetite1 apatite1 biotite1 & epidote are n infrequ5t con/itu5ts4 ,footnote #cbi3 ,zeits*r4 ,deuts*4 ,geol4 ,gesells*4 xxiii4 7#ahga71 p4 #ei4 ,footnote #ccj3 ,pr(essor ,judd 7,qu>t4 ,j\r4 ,geol4 ,soc4 xlii4 p4 #fb7 believes t orig9ally all ! gabbros conta9$ oliv9e1 & t :]e x is n[ abs5t1 x has be5 alt]$ into magnetite or s]p5t9e4 ,b 9 "s co>se massive gabbros ?is m9]al does n appe> to h be5 an ess5tial con/itu5t4 ,see op4 cit4 vol4 l4 p4 #fed4 ,footnote #cca3 ,op4 cit4 xli4 ,9 a lat] pap] he insi/s on ! gradation ( ! co>se granitoid v>ieties 7gabbros7 into holocry/all9e comp\nds1 :]e ! felsp> appe>s 9 la?-%apes ) cry/als or r\nd$ gra9s ( augite & oliv9e 7dol]ites71 & !nce into true basalts1 magma-basalts1 & ta*ylytes 7op4 cit4 xlii4 p4 #fb74 ,9 a rec5t /udy ( ! gabbros ( ! ,cuill9 ,hills ( ,skye by ,mr4 ,j4 ,j4 ,h4 ,teall & myself1 f\r *>act]i/ic types h be5 recogniz$4#ccb ,footnote #ccb3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid71 pp4 #fde-fei1 & ,plates xiii4 xxvi4-xxviii4 ,see also ,pr(4 ,judd's pap]1 op4 cit4 7#ahhf71 p4 #di4 7#a7 ,granulitic ,gabbros4--,^! are d>k1 f9e-gra9$ rocks :i* ext]nally resemble "s ( ! alt]$ basalts ( ! plateau-s]ies4 ,!y occur 9 b&s or %eets :i*1 s f> z c be made out1 are ! olde/ portions ( ! :ole gabbro mass4 ,"u ! microscope !y are f\nd to possess a f9ely granulitic /ructure1 & to consi/ ( gra9s ( pyrox5e 7augite1 b m usually ) ! inclusions *>act]i/ic ( diallage & pseudo-hyp]/h5e71 & ( felsp> alli$ to labradorite1 ) gre5 pseudomorphs agree+ 9 =m & size ) ! pyrox5e-gra9s1 b made ( m9ute prisms & fibres ( gre5 hornbl5de & a little *lorite4 7#b7 ,b&$ ,gabbros4--,^! are *>act]iz$ by a rem>kable arrangem5t 9 p>allel b&s ( diff]5t m9]al composition l ! b&+ ( anci5t gneisses4 ,?is /ructure w be m p>ticul>ly describ$ 9 lat] pages4 ,!y are co>se-gra9$ rocks compos$ ( pyrox5e1 plagioclase1 oliv9e & magnetite4 ,b ^! m9]als are n di/ribut$ equally ?r\gh ! mass4 ,! pale b&s conta9 mu* felsp>2 ! d>k b&s are l>gely compos$ ( ! f]ro-magnesian m9]als & magnetite4 ,! pyrox5e1 occurr+ z ord9>y augite1 n uncommonly %[s a t5d5cy to ophitic /ructure4 ,! felsp>1 a v>iety closely alli$ to labradorite1 occurs z gra9s1 z irregul> ophitic pat*es1 & also 9 =ms t give broad rectangul> sections4 ,oliv9e 9 an unalt]$ condition has be5 detect$ by ,mr4 ,teall 9 only "o specim51 & he ?9ks t ?is m9]al probably nev] play$ an important "p 9 ! orig9al con/itution ( ^! rocks4 ,its r\nd$ gra9s may be obs]v$ to h ! o!r m9]als m\ld$ r\nd !m1 :5ce x may be inf]r$ to be ( old] consolidation4 ,magnetite is g5]ally pres5t1 ei!r 9 r\nd$ gra9s or 9 l>ge irregul> masses4 ,?\gh x occurs also 9 /r+s trav]s+ ! o!r m9]als z a second>y product1 x mu/ und\bt$ly h ent]$ l>gely into ! orig9al composition ( ^! rocks4 ,x is f\nd enclos+ ! augite gra9s & behav+ l a gr\ndmass betwe5 ! felsp>s4 ,among ! d>k b&s !re occur n>r[ l5ticul> black lay]s 7's*li]5'7 compos$ entirely ( augite & iron-ore4 ,! extraord9>y diff]5ces betwe5 ! composition ( ! pale felspa?ic & ! d>k ultra-basic b&s are well br\ght out 9 ! foll[+ analyses by ,mr4 ,j4 ,hort ,play]1 ,no4 #a be+ f a light-col\r$ b& consi/+ ma9ly ( labradorite ) "s augite1 uralitic hornbl5de & magnetite2 ,no4 #b f a d>k b& compos$ ( augite1 magnetite & labradorite2 & ,no4 #c f a ?9 ultra-basic lay] ma9ly =m$ ( augite & magnetite4 ,all ^! specim5s 7 tak5 f ! ridge ( ,druim an ,eidhne1 on ! ea/]n side ( ! ,cuill9 ,hills1 ,skye4#ccc ,i4 ,,ii4 ,,iii4 ,silica #ebh #djb #bie ,titanic acid #e #dg #ib ,alum9a #agh #ie #ch ,f]ric oxide #ab #ig #agh ,f]r\s oxide #dh #abb #ahb ,f]ric sulphide #d #d ,oxide ( manganese #d #c ,lime #abi #aca #ajj ,magnesia #dh #hj #hg ,soda #cj #h #b ,pota% #e #b #a ,loss by ignition #ab #e #aj ---- ---- ---- #iie #iig #iib ---- ---- ---- ,spec4 grav4 #bia #ccf #chg ,footnote #ccc3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid71 p4 #fec4 ,b&$ /ructures h be5 recogniz$ 9 _m gabbros ( diff]5t ages4 ,see ! ref]5ces 9 ?is pap]2 also ,mr4 ,w4 ,s4 ,bayley1 ,j\rn4 ,geol4 ,*icago1 ii4 7#ahie71 p4 #had1 & vol4 iii4 p4 #a4 7#c7 ,co>se-gra9$ massive ,gabbros4--,^! rocks1 s abundant among ! great basic bosses ( ! ,inn] ,hebrides1 are *>act]iz$ by _! co>se granitic /ructure1 _! compon5t cry/als be+ sometimes m ?an an in* long4 ,!y occur z %eets1 ve9s & irregul> masses trav]s+ ! v>ieties ( gabbro already m5tion$4 ,!y consi/ ( ! same m9]als z ! b&$ =ms1 & inde$ are !mselves sometimes b&$4 ,!y are m uni=m 9 composition ?an ! typical b&$ gabbros1 ?\gh %[+ also "s v>iation 9 ! relative proportions ( _! con/itu5ts4 ,! specific gravity ( ?ree specim5s 0 f\nd to be #bhb1 #big1 & #cjf4 ,illu/ration3 ,fig4 #ccj4--;,granulitic & co>sely foliat$ gabbro trav]s$ by lat] ve9s ( felspa?ic gabbro1 ,druim an ,eidhne1 ,cuill9 ,hills1 ,skye4 7#d7 ,pale ,gabbros ( ! ,ve9s4--,^! occur abundantly z irregul> bran*+ ve9s1 f less ?an an in* to sev]al y>ds 9 wid?1 & cross all ! o!r v>ieties 7,fig4 #ccjccd74 ,_! :it5ess on wea!r$ surfaces makes !m conspicu\s by contra/ ) ! d>k br[n or black hue ( ! rocks :i* !y trav]se1 & %[s at once t !y mu/ be poor] 9 bases ?an ^!4 ,!y are f\nd on microscopic exam9ation to consi/ ( ! same m9]als z ! m co>sely cry/all9e gabbros1 b ) a mu* great] abundance ( ! felsp>4 ,!y conta9 also apatite1 & hornbl5de appe>s to pr$om9ate 9 !m ov] augite4 ,!y are to be di/+ui%$ f ! pale ve9s t =m apophyses f ! intrusive granophyres4 ,footnote #ccd3 ,figs4 #ccj1 #ccf & #ccg are f photographs tak5 = ! ,geological ,survey by ,mr4 ,r4 ,lunn4 ,troctolite 7,=ell5/e974--,?is beautiful v>iety ( plagioclase-oliv9e rock occurs z a conspicu\s feature on ! ea/ side ( ! gabbro-area ( ! isl& ( ,rum4 ,x =ms a sill on ! side ( ! m\nta9 ,allival1 9 :i* ! compon5t m9]als are drawn out p>allel ) ! upp] & "u surfaces ( ! b$ 7,fig4 #cda74 ,s m>k$ is ?is fl[-/ructure t h&-specim5s might readily be tak5 at ! fir/ glance = anci5t s*i/ose lime/one4 ,! felspa?ic +r$i5t 7probably labradorite or anor?ite7 is :ite1 & its la?-%ap$ cry/als h rang$ !mselves ) _! long axes p>allel to ! l9e ( fl[4 ,! oliv9e occurs 9 p]fectly fre% gra9s1 :i* 9 h&-specim5s h a delicate gre5 t9t4 ,"u ! microscope !y appe> col\rless1 & are p5etrat$ by ! felsp> prisms 9 ophitic int]gr[?4 ,!re is a small quantity ( a pale br[ni% augite1 :i* n only occurs 9 w$ge-%ap$ portions betwe5 ! felsp>s1 b also z a n>r[ zone r\nd ! oliv9es4#cce ,consid]able diff]5ces are visible 9 ! developm5t ( ! fl[-/ructure1 & ) ^! !re appe> to be accompany+ v>iations 9 ! microscopic /ructure4 ,dr4 ,hat*1 to :om ,i submitt$ my specim5s1 in=m$ me t 9 "o ( !m1 :]e ! fl[-/ructure is s m>k$ z to give a f9ely s*i/ose aspect to ! rock1 !re is a l>g] proportion ( augite1 "s ( :i* exhibits a di/9ct diallagic /rip+2 ! oliv9e gra9s %[ no ophitic /ructure1 b are sometimes completely emb$d$ 9 ! augite4 ,to ?is rem>kable fl[-/ructure ,i %all aga9 ref] 9 connection ) ! light x ?r[s on ! b$d$ "* ( mu* ( ! gabbro bosses4 ,footnote #cce3 ,,ms4 ( ,dr4 ,hat*4 ,betwe5 ! diff]5t basic intrusive igne\s rocks ( ! ,inn] ,hebrides1 z ,pr(essor ,judd has %[n1 !re are _m gradations accord+ to ! v>y+ proportions ( ! *ief compon5t m9]als4 ,?us f ! oliv9e-gabbros1 by ! dim9ution or disappe>ance ( ! augite we get su* rocks z troctolite2 :]e ! plagioclase dim9i%es or vani%es1 we h diff]5t =ms ( picrite2 :]e ! oliv9e is left out1 we come to comp\nds1 l eucrite2 :ile by ! less5+ or disappe>ance ( ! felsp> & augite1 we are l$ to ultra basic comp\nds1 consi/+ 9 greate/ "p ( oliv9e1 l lh]zolite1 dunite & s]p5t9e4 ,to "s ( ! features & probable orig9 ( ^! *emical & m9]alogical div]sities 9 ! same great eruptive mass fur!r ref]5ce w be made 9 lat] pages4 ii4 ,,relations ,,( ,,! ,,gabbros ,,to ,,! ,,o!r ,,memb]s ,,( ,,! ,,volcanic ,,s]ies ,v>i\s op9ions h be5 express$ reg>d+ ! connection betwe5 ! amorph\s eruptive rocks ( ! hill-gr\ps & ! level basalt-%eets ( ! plateaux4 ,jameson1 ?\gh he l&$ at ,rudh' an ,duna91 9 ,skye1 :]e ?is connection c readily be f\nd1 does n seem to h made any attempt to asc]ta9 x4 ,he notic$ t ! l[] gr\nds 7 =m$ ( basalt1 & t ! m\nta9s appe>$ to be :olly compos$ ( sy5ite & hornbl5de rock1 trav]s$ by basalt ve9s4#ccf ,maccullo*1 9 _m passages ( 8 ,we/]n ,isl&s1 alludes to ! subject z "o :i* he knew w\ld int]e/ geologi/s1 b ab\t :i* he felt t he c\ld give no satisfactory in=mation1 & ) *>act]i/ic v]biage he ref]s to ! impossibility ( det]m9+ b\nd>ies1 to ! transition f "o rock into ano!r1 to ! inaccessible nature ( ! gr\nd1 to ! almo/ insup]able ob/acles t imp$e exam9ation1 to ! di/ance f human habitation1 & to ! /ormy climate1--a =midable li/ ( b>ri]s1 9 pres5ce ( :i* he leaves ! relative position & age ( ! rocks unsettl$4#ccg ,footnote #ccf3 ,m9]alogical ,travels 7#ahac71 vol4 ii4 p4 #gb4 ,footnote #ccg3 ,see 8 ,we/]n ,isl&s1 vol4 i4 pp4 #cfh1 #cgd1 #che1 #chf4 ,) mu* admiration = ! insight & zeal1 am\nt+ almo/ to g5ius1 :i* ,maccullo* display$ 9 8 "w among ! ,we/]n ,isl&s1 at a "t :51 ) poor maps & inadequate means ( locomotion1 geological survey+ 0 a m difficult task ?an x is n[1 ,i h f\nd x impossible to foll[ 9 8 foot/eps ) 8 descriptions 9 h&1 & n to wi% t = 8 own fame he _h be5 cont5t to claim cr$it only = :at he _h se54 ,8 actual a*ievem5ts 7 en\gh to make ! reputation ( half a doz5 good geologi/s4 ,x 0 un=tunate t he did n realize h[ inexhau/ible nature is1 h[ impossible x is = "o man to see & und]/& e fact ev5 9 ! little corn] ( nature :i* he may claim to h explor$4 ,he seems to h _h a morbid fe> le/ any "o %\ld aft]w>ds discov] some?+ he _h miss$2 he writes z if ) ! object ( dissuad+ m5 f travell+ ov] 8 gr\nd1 & he inde$ tacitly lays claim to any?+ !y may asc]ta9 by av]r+ t ^? :o may foll[ him w f9d a great deal t is n "h describ$1 al?\gh little t has n be5 exam9$ 7p4 #cgc74 ,pr9cipal ,=bes long ago expos$ ?is weak side ( ,maccullo* & 8 "w 7,ed94 ,new ,phil4 ,j\rn4 xl4 #ahdf1 p4 #hb74 ,von ,oy5haus5 & ,von ,de*51 :o wrote s excell5t an acc\nt ( _! visit to ,skye1 & :o trac$ mu* ( ! b\nd>y-l9e betwe5 ! gabbros & ! o!r m\nta9\s eruptive masses 7sy5ite71 seem to h made no attempt to "w out ! connection betwe5 ! =m] & ! re/ ( ! volcanic rocks4#cch ,footnote #cch3 ,k>/5's ,ar*iv1 i4 p4 #ii4 ,!y frankly admit t ! relation ( ! hyp]/h5e rock to ! o!r trap rocks 0 n asc]ta9$4 ,j4 ,d4 ,=bes1 9 8 able sket* ( ! ,topography & ,geology ( ! ,cu*ull9 ,hills1 0 ! fir/ to recognize ! sup]position ( ! hyp]/h5e rock ^u ! common trap rocks--t is1 ! plateau-basalts4 ,he 0 dispos$ to consid] ! hyp]/h5e mass z a va/ b$1 ?9n+ out bo? ways1 & incl9$ at a mod]ate angle t[>ds ! ,s4,e4#cci ,footnote #cci3 ,ed94 ,new ,phil4 ,j\rn4 xl4 7#ahdf71 pp4 #he1 #hf4 ,pr(essor ,judd reg>d$ ! bosses ( basic & acid rocks t rise out ( ! b$d$ basalts z ! basal cores ( enorm\sly d5ud$ volcanic cones4 ,he believ$ ! granitoid rocks to h be5 fir/ erupt$1 & t aft] a long int]val ! basic masses 7 =c$ ?r\gh !m1 p>tly consolidat+ und]nea? & p>tly appe>+ at ! surface z ! plateau-basalts4#cdj ,t ! ord] ( appe>ance ( ! sev]al rocks has be5 exactly ! rev]se ( ?is suppos$ sequ5ce 0 fully e/abli%$ by me 9 ! ye> #ahhh1 & has s9ce be5 amply confirm$4#cda ,pr(essor ,zirkel recogniz$ t ! gabbros are a dep5d5ce ( ! basalts1 t !y ov]lie !m1 & t on ! nak$ flanks ( ! m\nta9s !y are regul>ly b$d$ ) !m4#cdb ,footnote #cdj3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxx4 7#ahgd71 p4 #bdi4 ,footnote #cda3 ,trans4 ,roy4 ,soc4 ,ed94 xxxv4 7#ahhh71 pp4 #abb et seq42 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid71 pp4 #baf1 #fde2 vol4 lii4 7#ahif71 p4 #chd1 & ,mr4 ,h>k]1 ibid4 p4 #cbj4 ,footnote #cdb3 ,zeits*rift4 ,deuts*4 ,geol4 ,gesells*4 xxiii4 7#ahga71 pp4 #eh1 #ib4 ,up to ! "t ( ! publication ( my memoir 9 #ahhh no "o _h trac$ out 9 m detail ! actual b\nd>ies ( ! sev]al rocks on ! gr\nd1 s z to obta9 evid5ce ( _! true relations to ea* o!r z reg>ds /ructure & age4 ,"s ( ! num]\s imp$im5ts record$ by ,maccullo* no d\bt ret>d$ ! inve/igation4 ,b1 z ,=bes s well po9t$ out1 !re is really no s]i\s difficulty 9 det]m9+ ! true /ructural connection ( ! amorph\s rocks ) ea* o!r & ) ! b$d$ basalts ( ! plateaux4 ,i h asc]ta9$ !m 9 ea* ( ! di/ricts1#cdc & h f\nd t !re _c be ! lea/ d\bt t ! amorph\s bosses1 bo? basic & acid1 are y\ng] ?an ! surr\nd+ b$d$ basalts1 & t ! acid protrusions are on ! :ole y\ng] ?an ! basic1 ,i %all n[ proce$ to %[ h[ ^! conclusions are e/abli%$ by ! evid5ce ( ea* ( ! areas :]e ! sev]al k9ds ( rock occur4 ,footnote #cdc3 ,9 two ( my excursions 9 ,mull1 & once 9 ,skye1 ,i 0 accompani$ by my =m] colleague ,mr4 ,h4 ,m4 ,cadell1 :o r5d]$ me great assi/ance 9 mapp+ ^? regions4 iii4 ,,descriptions ,,( ,,! ,,sev]al ,,gabbro-,,di/ricts #a4 ,! ,gabbro ( ,skye ,! l>ge/1 mo/ picturesque1 & to ! geologi/ mo/ important area ( ,t]ti>y gabbro 9 ,brita91 is t ( ,skye 7,map4 ,,vi474 ,?\gh1 l e o!r portion ( ! ,t]ti>y volcanic di/ricts1 x has suff]$ enorm\s d5udation1 & has !reby be5 tr5*$ to ! v core1 x reveals1 m conspicu\sly & cle>ly ?an c be se5 any:]e else1 ! relation ( ! gabbro to ! b$d$ basalts on ! "o h&1 & to ! acid protrusions on ! o!r4 ,its *ief portion is t :i* rises into ! gr\p ( ! ,cuill9 ,hills1 :i* = blackness ( hue1 rugg$ness ( surface1 jagg$ness ( cre/1 & g5]al grimness ( aspect1 h c]ta9ly no rivals )9 ! limits ( ! ,briti% ,isles 7,fig4 #cca74 ,x has long be5 kn[n to ext5d ea/w>ds into ,bla? ,bhe9n 7,blav57 & its imm$iate nor!rn neighb\rs4 ,!re is1 inde$1 no break :atev] betwe5 ! rock ( ! ,cuill9s & t ( ! hills on ! ea/ side ( ,/ra? na ,crei!a*4 ,9 ,/ra? ,m ! gabbro is int]rupt$ by ! granitoid mass ( ! ,r$ ,hills4 ,pat*es ( x1 h[ev]1 occur fur!r to ! ea/1 ev5 z f> z ! ,s\nd ( ,scalpa4 ,illu/ration3 ,fig4 #cca4--,scuir na ,gillean1 ,cuill9 ,hills1 %ew+ ! *>act]i/ic craggy =ms ( ! ,gabbro4 7,f a photograph by ,mr4 ,abraham1 ,keswick47 ,if we ?r[ out ( acc\nt ! invad+ granitoid rocks1 & look ^u ! :ole tract )9 :i* ! gabbro occurs z orig9ally "o connect$ area1 we f9d t x cov]$ an elliptical space measur+ ab\t n9e miles f s\?-we/ to nor?-ea/ & six miles f nor?-we/ to s\?-ea/1 & embrac+ at lea/ #dj squ>e miles4#cdd ,b t its orig9al size 0 great] is /rik+ly %[n m p>ticul>ly on ! we/]n m>g91 :i* l t ( ! basalt-esc>pm5ts1 has obvi\sly be5 det]m9$ by d5udation1 = its sep>ate b$s pres5t _! truncat$ ends to ! horizon all along ! flanks ( ! ,cuill9s1 f ! head ( ,gl5 ,brittle r\nd to ,lo* ,scavaig 7,fig4 #ccb71 & f ,/ra? na ,crei!a* r\nd ! s\!rn flanks ( ,bla? ,bhe9n to ,lo* ,slap9 & ,/ra? ,m4 ,footnote #cdd3 ,?\gh ?is & ! o!r bosses are "h spok5 ( z consi/+ ( gabbro1 x w be und]/ood t ?is rock only con/itutes ! l>g] portion ( _! mass1 :i* includes also dol]ites & o!r m basic comp\nds1 toge!r ) involv$ portions ( ! plateau-basalts & masses ( agglom]ate :i* probably m>k ! position ( old] v5ts4 ,illu/ration3 ,fig4 #ccb4--,section across ,gl5 ,brittle1 to %[ ! g5]al relations ( ! ,b$d$ ,basalts 7a7 & ! ,gabbros 7b74 ,! fir/ po9t to be asc]ta9$ 9 reg>d to ! gabbro & associat$ basic rocks ( ! m\nta9\s tract is _! connection 9 geological /ructure & age ) ! b$d$ basalts ( ! plateau4 ,?is initial & fundam5tal relation1 z ,=bes long ago said1 c be exam9$ along ! :ole we/]n & s\!rn flank ( ! ,cuill9 ,hills1 f ! foot ( ,gl5 ,sliga*an r\nd to ! m\? ( ,lo* ,scavaig4 ,ev5 f a di/ance1 ! obs]v]1 :o is fav\r$ ) cle> wea!r1 c readily trace ! almo/ level %eets ( basalt till !y dip g5tly "u ! d>k]1 m massive rock ( ! hills4 ,t\ri/s1 :o approa* ,skye by way ( ,lo* ,coruisk1 h an opportunity1 z ! /eam] ne>s ! isl& ( ,soay1 ( foll[+ ) ! eye ! basalt-t]races ( ! promontory ( ,rudh' an ,duna9 until !y disappe> "u ! gabbro ( ! la/ spur ( ! ,cuill9s t gu>ds ! we/]n entrance to ,lo* ,scavaig4 ,:at is s evid5t at a di/ance becomes /ill m /rik+ :5 view$ f ne>] gr\nd4 ,n[h]e c x be m impressively se5 ?an at ! head ( ,gl5 ,brittle4 ,look+ we/w>ds1 ! travell] sees 9 front ( him only ! famili> level t]races & gre5 slopes ( ! basalt-plateau1 ris+ plat=m above plat=m to a height ( ne>ly #aejj feet above ! sea4 ,b turn+ to ! ea/1 he beholds ! d>k1 gloomy1 cauldron-l ,corry na ,crei*e1 f :i* rise "s ( ! rugg$e/ & l(tie/ cre/s ( ! ,cuill9s4 ,on ! hills t project f ei!r side ( ?is recess & half enclose x1 ! b$d$ basalts m\nt f ! bottom ( ! valley1 ) _! l9es ( p>allel t]race dipp+ g5tly inw>d bel[ ! black rugg$ gabbro t cr[ns !m & sweeps r\nd to =m ! back or head ( ! corry4 ,d[n ! :ole l5g? ( ,gl5 ,brittle ! same /ructure conspicu\sly gov]ns ! topographical features4 ,on ! "r h&1 ! ord9>y t]rac$ basalts =m ! slopes2 & !y rise = "s #ejj or #fjj feet up ! ea/]n side1 until !y pass "u ! d>k]1 m rugg$1 & less di/9ctly b$d$ rocks ( ! m\nta9s 7,fig4 #ccb74 ,! dip ( ! :ole s]ies is "h at a g5tle angle t[>ds s\?-ea/1 t is1 into or "u ! ma9 mass ( ! ,cuill9 gr\p4 ,:51 h[ev]1 we proce$ to exam9e ! junction betwe5 ! two rocks we f9d x to be less simple ?an x appe>s4 ,x is n an in/ance ( m]e sup]position4 ,! gabbro unque/ionably ov]lies ! basalts1 & is !re=e ( y\ng] date4 ,b x ov]lies !m1 n z !y re/ on ea* o!r1 9 regul> con=mable sequ5ce ( eruption1 b intrusively1 z a sill does ^u ! rocks on :i* x appe>s to foll[ 9 ! unbrok5 ord] ( accumulation4 ,?is important /ructure may be asc]ta9$ 9 almo/ any ( ! _m sections cut by ! torr5ts :i* h s deeply tr5*$ ) gullies ! flanks ( ! hills4 ,/>t+ f ! ord9>y b$d$ basalts1 we obs]ve1 9 m\nt+ ! slopes & approa*+ ! gabbro1 t ! rocks ins5sibly assume t indurat$ %att]y "*1 :i* has be5 ref]r$ to z *>act]i/ic ( !m r\nd ! m>g9s ( v5ts1 & :i* w be %[n to be n less s 9 contact ) l>ge eruptive masses ( basic or acid rock4#cde ,b$s ( dol]ite make _! appe>ance among ! basalts1 s di/9ctly cry/all9e1 & s simil> 9 "* to ! rocks ( ! sills1 t !re c be little hesitation 9 reg>d+ !m z intrusive4 ,^! sills increase 9 size & numb] z we asc5d1 ?\gh h>d5$ amygdaloidal basalts may /ill be obs]v$4 ,true gabbros !n sup]v5e 9 massive b$s1 & at la/ we f9d ourselves entirely )9 ! gabbro area1 :]e1 h[ev]1 ?9 b&s ( highly alt]$ basalt may /ill = "s di/ance appe>4 ,"o fur!r fact w g5]ally be notic$1 viz4 t be=e rea*+ ! ma9 mass ( gabbro1 ve9s & sills ( basalt1 z well z ( v>i\s felsitic & porphyritic memb]s ( ! acid gr\p1 come 9 abundantly1 cross+ & recross+ ea* o!r 9 ! mo/ intricate network4 ,! base ( ! ?ick gabbro-%eets is ?us ano!r horizon on :i*1 z on t bel[ ! plateau-basalts1 intrusive masses h be5 especially develop$4 ,?r\gh all ^! rocks num]\s p>allel basalt-dykes1 runn+ 9 a g5]al p]si/5t ,n4,n4,w4 direction1 ) a lat] ,n4,e4 s]ies1 rise f bel[ ! sea-level up ev5 to ! v cre/s ( ! ,cuill9s 7,fig4 #ccc74 ,footnote #cde3 ,?is indurat$1 alt]$ "* ( ! b$d$ basalts ne> ! intrusive bosses & sills w be m p>ticul>ly describ$ 9 a lat] *apt] 9 connection ) ! granophyre intrusions 7see p4 #chf74 ,! metamorphism induc$ by ! basic rocks has g5]ally be5 less pron\nc$ ?an t effect$ by ! acid masses4 ,! sections on ! we/]n side ( ! gabbro area ( ,skye ?us prove t ?is rock inosculates ) ! b$d$ basalts by s5d+ into !m1 betwe5 _! b$d+ planes1 %eets :i* v>y 9 texture f f9e dol]ites at ! outside into co>se gabbros fur!r t[>ds ! c5tral mass1 & t ?is intrusion has be5 accompani$ by a c]ta9 am\nt ( induration ( ! old] rocks4 ,illu/ration3 ,fig4 #ccc4--,view ( ! cre/ ( ! ,cuill9 ,hills1 %[+ ! wea!r+ ( ! gabbro along its jo9ts1 & ( a comp\nd basic dyke :i* rises ?r\gh x4 7,f a photograph by ,mr4 ,abraham1 ,keswick47 ,on ! ea/]n side1 ! same /ructure c be ev5 m di/9ctly se51 = x is n only expos$ 9 gullies & /eep declivities1 b c be trac$ outw>d into ! basalt-plateau4 ,9 ! promontory ( ,/ra?aird1 ,jurassic s&/ones & %ales1 :i* =m ! coa/-l9e & l[] gr\nds1 are surm\nt$ by ! b$d$ basalts4 ,d5udation has cut ! plateau into two p>ts4 ,! small] ( ^! makes ! outli] t rises into ,b5 ,meabo/ 7#aabh feet74 ,! l>g] /ret*es cont9u\sly f ,gl5 ,scaladal & ,/ra?aird ,h\se nor?w>d into ,bla? ,bhe9n4 ,h5ce f ! ord9>y t]rac$ basalts1 ) _! amygdaloids1 ?9 tuffs1 r$ p>t+s1 & seams ( lignite1 e /ep c be foll[$ into ! huge gabbro m\nta94 ,/>t+ f ! black ,jurassic %ales on :i* ! l[e/ basalt lies1 we walk ov] ! successive t]races up into ! project+ ridge ( ,an da ,bhe9n4 ,b z we asc5d1 %eets ( dol]ite & gabbro make _! appe>ance betwe5 ! basalts1 :i* gradually assume ! alt]$ aspect already notic$4 ,! dip ( ! :ole s]ies is at a l[ angle nor?w>ds1 & ! b$s c be foll[$ r\nd ! head ( ! ,gl5 nan ,leac into ! s\!rn slopes ( ,bla? ,bhe9n4 ,se5 f ! ea/]n side ( ?is valley1 ! b$d$ "* ( t m\nta9 is rem>kably di/9ct1 b x becomes less m>k$ t[>ds ! upp] "p ( ! ridge :]e ! gabbros prepond]ate4 ,"o ( ! mo/ /rik+ features ( ! locality is ! numb] & p]si/5ce ( ! dykes1 :i* /rike across f ! ord9>y unalt]$ basalts ( ! plateau up into ! highe/ gabbros ( ! range4 ,:]e less durable ?an ! intractable gabbro1 !y h wea!r$ out on ! face ( ! precipices1 !reby caus+ ! v]tical rifts & ga%es & ! deep not*es on ! cre/ t =m s m>k$ a feature 9 ! sc5]y4 ,on ! o!r h&1 !y are (t5 less de/ructible ?an ! plateau-basalts1 & h5ce 9 ! ,gl5 nan ,leac !y may be se5 project+ z l[ dams across ! /ream :i* ?r[s itself ov] !m 9 picturesque wat]falls4 ,! y\nge/ dykes 9 ! ,bla? ,bhe9n gr\p ( hills1 h be5 f\nd by ,mr4 ,h>k] to h a nor?-ea/]ly tr5d1 & a nor?-we/]ly hade ( ab\t #dj1 & to give a /ratifi$ appe>ance to ! gabbro :5 view$ f a di/ance4 ,! deep d>k holl[ ( ! ,coire ,uaignei* has be5 cut out ( ! v core ( ,bla? ,bhe9n1 & lays b>e ! /ructure ( ! ea/ "p ( ! m\nta9 9 ! mo/ impressive z well z in/ructive way 7,fig4 #ccd74 ,by asc5d+ into ?is recess f ,lo* ,slap91 we pass ov] ! :ole s]ies ( rocks1 & c exam9e !m 9 an almo/ cont9u\s section 9 ! b$ ( ! /ream & on ! b>e rocky slopes on ei!r side4 ,s&/ones & %ales ( ! ,jurassic s]ies ext5d up ! ,allt na ,dunai*e = ne>ly a mile1 mu* ve9$ ) basalt & qu>tz-porphyry1 by :i* ! s&/ones are locally indurat$ into qu>tzite4 ,at la/ ^! /rata are ov]lapp$ by ! basalts ( ! ,/ra?aird plateau1 :i* ) a m>k$ incl9ation to ,n4,n4,w41 "h dip t[>ds ! m\nta9s4 ,b by ! "t ^! rocks h rea*$ ! valley1 !y h already lo/ _! usual br[n col\r & crumbl+ surfaces1 & h assum$ ! indurat$ spl9t]y "*1 ?\gh /ill %[+ _! amygdaloidal /ructure4 ,!y are mu* trav]s$ by felsitic ve9s & /r+s :i* proce$ f a broad b& ( f9e-gra9$ hornbl5de-granite t runs up ! bottom ( ! ,coire ,uaignei* &1 asc5d+ ! col1 crosses x s\?-we/w>ds into ! ,gl5 nan ,leac4 ,on ! left or s\?-ea/]n side ( ?is intrusive mass1 a portion ( ,lias %ales & lime/one 7"h & !re alt]$ into :ite m>ble7 is traceable = sev]al hundr$ y>ds up ! /ream4#cdf ,footnote #cdf3 ,?is lime/one 0 =m]ly id5tifi$ by me ) ! ,cambrian /rata ( ! di/rict4 ,x 0 notic$ by ,von ,oy5haus5 & ,von ,de*51 :o1 z ,mr4 ,h>k] has rec5tly asc]ta9$1 correctly believ$ x to be a portion ( ! ,lias torn (f & c>ri$ upw>d by ! eruptive rocks 7,k>/5's ,ar*iv1 i4 p4 #gi74 ,! b$d$ basalts ( ,/ra?aird1 aft] dipp+ d[n t[>ds ! ,n4,n4,w41 b5d up :]e !y are int]b&$ ) dol]ites & gabbros1 & =m ! prom95ce call$ ,an ,/ac1 :i* rises z ! ea/]n b\nd>y ( ! ,coire ,uaignei*4 ,_! /eep dip away f ! m\nta9 is well se5 f ! ea/ side1 & _! outw>d incl9ation is cont9u$ into ! ridge to ! s\?w>d4 ,simil> rocks appe> on ! o!r flank ( ! b& ( granite1 & =m ! base ( ,bla? ,bhe9n4 ,!y are likewise cont9u$ 9 ! m\nta9s fur!r nor? call$ ,sgurr nan ,ea* & ,belig1 :]e !y dip 9 a nor!rly direction away f ,bla? ,bhe9n1 :i* seems to be ! c5tre ( uprise1 ) ! gabbro-%eets dipp+ away f x4 ,! b$d$ basalts h be5 trac$ by ,mr4 ,h>k] up to a height ( well ov] #bjjj feet on ! ,bla? ,bhe9n range4 ,!y are ( ! usual alt]$1 indurat$1 & spl9t]y "*4 ,! intrusive %eets int]pos$ betwe5 !m become ?ick] & m abundant high] up1 until !y con/itute ! ma9 mass ( ! m\nta94 ,b t !y are 9 sep>ate %eets1 & n 9 "o amorph\s mass1 c be recogniz$ by ! p>allel l9es t m>k _! b\nd>ies4 ,! junction ( ! gabbro sills & ! lavas is a v irregul> "o1 portions ( ! latt] rocks be+ envelop$ 9 ! intrusive sills4 ,! granite :i* s5ds out ve9s into ! surr\nd+ rocks is obvi\sly ! y\nge/ protrusion ( ! locality1 except ( c\rse ! basalt-dykes :i* cross x1 & :i* are n[h]e se5 9 a m impos+ display ?an r\nd ! flanks ( ,bla? ,bhe9n4 ,a section across ! corry %[s ! /ructure repres5t$ 9 ,fig4 #ccd4 ,x is ?us demon/rable t :5 its l9e ( junction ) ! surr\nd+ plateau-basalts is trac$ 9 "s detail1 ! gabbro is f\nd to ov]lie !m z a :ole1 b also to be int]calat$ ) !m 9 innum]able b$s1 b&s1 or ve9s :i* rapidly die out z !y rec$e outw>ds f ! ma9 c5tral mass2 t ^! int]pos$ b$s are intrusive %eets or sills f t mass :i* h cut (f & envelop$ portions ( ! basalts1 & t ! contigu\s b$d$ basalts %[ m or less m>k$ metamorphism4 ,we h n[ to consid] ! /ructure ( ! int]ior ( ! gabbro area ( ! ,cuill9 ,hills4 ,! fir/ impression ( ! geologi/ :o visits t wild di/rict is t ! ma9 mass ( rock is z ?or\ghly amorph\s z a core ( granite4 ,yet a little fur!r exam9ation w reveal to him _m v>ieties ( texture1 sometimes graduat+ into1 sometimes %>ply m>k$ (f f1 ea* o!r1 & sugge/+ t ! rock is n ! product ( "o s+le protrusion4 ,he w notice fur!r indications ( successive dis*>ges or extravasations ( cry/all9e mat]ial dur+ probably a protract$ p]iod ( "t1 & 9 ! intricate network ( ve9s cross+ ea* o!r & ! g5]al body ( ! rock 9 e direction1 z well z 9 ! sy/em ( basalt-dykes t trav]se all ! o!r rocks1 he w recognize ! completion ( ! evid5ce ( repeat$ r5ewals ( subt]ranean en]gy4 ,illu/ration3 ,fig4 #ccd4--,section across ! ,coire ,uaignei*1 ,skye4 a1 b1 ,jurassic s&/ones & %ales2 c c1 b$d$ basalts & dol]ites2 d d1 gabbros & dol]ites ) indurat$ basalts2 e1 f9e-gra9$ hornbl5de-granite s5d+ ve9s into surr\nd+ rocks2 f f1 basalt-dykes runn+ ?r\gh all ! o!r rocks4 ,b ! obs]v] w be /ruck ) ! abs5ce ( ! m usual pro(s ( volcanic activity 9 su* =ms z vesicul> lavas & abundant masses ( slag1 bombs & tuffs1 :i* are commonly associat$ ) ! idea ( ! c5tre ( a volcanic orifice1 ?\gh he w meet ) isolat$ masses ( co>se volcanic agglom]ate )9 ! gabbro area & along "s p>ts ( its junction ) ! granophyre4 ,! g5]al *>act]s ( ! rocks ar\nd him sugge/ t he /&s1 z x 71 f> b5ea? t upp] "p ( ! e>?'s cru/ :i* is famili> to u 9 ! ph5om5a ( mod]n volcanoes2 t he has be5 admitt$ into ! he>t ( "o ( ! deep] lay]s1 :]e he c /udy ! op]ations t g on at ! v roots ( an active v5t4 ,:5 ! geologi/ beg9s a m leisurely & sy/ematic exam9ation ( ! int]ior ( ! gabbro area ( ,skye he soon sees reason to modify ! impression he may at fir/ h receiv$ t ?is rugg$ region pres5ts ! *>act]s ( "o s+le eruptive mass4 ,! m he climbs among ! hills ! m w he meet ) evid5ce ( long-cont9u$ & (t-repeat$ extravasation1 "o portion hav+ solidifi$ be=e ano!r broke ?r\gh x1 & bo? hav+ be5 subsequ5tly disrupt$ by /ill lat] protrusions4 ,b if by *ance he %\ld beg9 8 exam9ation ( ! gr\nd ^u "s ( ! m typically b&$ v>ieties ( rock1 he may = a "t almo/ refuse to admit t ^! c be ei!r ( volcanic orig9 or ( ,t]ti>y age4#cdg ,he w f9d among !m su* />tl+ c\nt]p>ts ( ! /ructure ( ! anci5t ,lewisian gneiss ( ! ,nor?-,we/ ( ,scotl& t he may well be p>don$ if = a "t he seeks = evid5ce t !y really d belong to t primeval =mation1 & h only be5 accid5tally involv$ among ! ,t]ti>y volcanic rocks4 ,if1 = in/ance1 he %\ld l& 9 ,lo* ,scavaig1 & fir/ set foot ^u ! gabbros z !y appe> ar\nd ,lo* ,coruisk1 he w\ld f9d himself ^u masses ( grey co>sely cry/all9e1 rudely b&$ rock1 l mu* ( ! old gneiss ( ,su!rl& & ,ross4 ,asc5d+ ov] ! ice-worn domes1 he w\ld notice t ! b&+ becomes "h & !re m def9itely m>k$ by /rong diff]5ces 9 texture & col\r1 :ile else:]e x disappe>s & is replac$ by a granitoid arrangem5t ( ! cry/als1 :i* are (t5 z l>ge z walnuts4 ,footnote #cdg3 ,see ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 l4 pp4 #bag1 #feg1 & a pap] by ! au?or1 ,sur la ,/ructure rubanne des plus anci5s ,gneiss et des ,gabbros ,t]tiaires1 ,compt4 r5d4 ,cong4 ,gol4 ,int]nat4 #ahid1 p4 #aci4 ,illu/ration3 ,fig4 #cce4--;,b&$ & puck]$ gabbro1 ,druim an ,eidhne1 ,gl5 ,sliga*an1 ,skye4 ,n[h]e is ! gneissoid b&+ m beautifully develop$ ?an on ! ea/ side ( ! ,cuill9 gr\p ne> ! head ( ,gl5 ,sliga*an along ! ridge ( ,druim an ,eidhne4 ,x 0 at ?is locality t ! f\r typical /ructures 7 obs]v$ :i* h already be5 ref]r$ to 7p4 #cbi74 ,! v>ieties ( col\r & composition dep5d ^u ! exce$+ly irregul> di/ribution ( ! compon5t m9]als4 ,! pal] b&s1 ri* 9 felsp>1 lie p>allel ) d>k br[n b&s full ( pyrox5e1 oliv9e & magnetite1 9 :i*1 moreov]1 ?9 ribs ( gli/5+ black consi/ 9 l>ge "p ( ! iron ore4 ,^! lay]s v>y 9 ?ickness f m]e pa/ebo>d-l lam9 to b$s a y>d or m 9 ?ickness4 ,)9 a space ( a few squ>e y>ds _! p>allelism rem9ds "o ( /ratifi$ deposits 7,fig4 #ccf71 b trac$ ov] a wid] space !y are f\nd to be m or less irregul> 9 ?ickness & l5ticul> 9 =m4 ,illu/ration3 ,fig4 #ccf4--;,b&$ /ructure 9 ! ,gabbro1 f ! ridge ( ,druim an ,eidhne betwe5 ,lo* ,coruisk & ,gl5 ,sliga*an4 ,! resemblance to gneisses1 & sometimes to ! fl[-/ructure ( co>se rhyolites1 is /ill fur!r su/a9$ by occasional undulations or m9ute puck]+s 7,fig4 #cce74 ,/ill m extraord9>y are ! examples ( ! actual plication ( a gr\p ( successive b&s1 z %[n 9 ,fig4 #ccg1 :]e9 su* a gr\p ab\t t5 feet ?ick is %[n to h be5 d\bly fold$ betwe5 p>allel b&s above & bel[4 ,?is /ructure is n due to any de=mation ( ! gabbro long subsequ5t to ! consolidation ( ! mass4 ,x belongs to ! ph5om5a ( protrusion & solidification4 ,an exam9ation ( ?9 slices ( ^! rocks "u ! microscope reveals no evid5ce ( cru%+4 ,on ! contr>y1 ! m9]als ( "o b& int]lock ) ^? ( ! b& adjo9+1 9 su* a mann] z to prove t ! diff]5ces ( composition _c be due to cru%+ & %e>+ or to successive intrusion1 b mu/ h be5 pres5t be=e ! f9al consolidation ( ! :ole rock4#cdh ,footnote #cdh3 ,mr4 ,j4 ,j4 ,h4 ,teall & ,a4 ,g41 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid71 p4 #feb4 ,! conclusion :i* seems mo/ consonant ) ! facts is t ! magma :i* suppli$ ! visible masses ( gabbro 9 ,skye exi/$ bel[ 9 a het]og5e\s condition1 t portions ( x1 diff]+ consid]ably f ea* o!r 9 composition1 7 simultane\sly intrud$1 & t by ! de=mation ( ^! portions dur+ _! intrusion _! pres5t plicat$ /ructures 7 produc$4 ,a c>eful /udy ( ^! b&$ gabbros (f]s _m sugge/ive po9ts ( comp>ison ) ! gneisses & anor?osite 7,norian7 rocks ( pre-,cambrian age4 ,x seems 9 ! highe/ degree probable t ! b&$ /ructures & peculi> m9]al aggregation 9 ^! anci5t rocks arose "u conditions closely analog\s to1 if n id5tical )1 ^? 9 :i* ! ,t]ti>y gabbros ( ,skye orig9at$4#cdi ,footnote #cdi3 ,consult ! ,memoirs cit$ 9 ! footnote on p4 #cdb4 ,simil> /ructures are f\nd to be widely develop$ ?r\gh ! gabbros ( ! ,cuill9 ,hills4 ,n only are ^! rocks dispos$ 9 di/9ct b$s1 b _m ( ! b$s display ! mo/ p]fect b&+4 ,?us ! m\nta9s t surr\nd ! head ( ,lo* ,scavaig & sweep r\nd ,lo* ,coruisk up to ! great spl9t]$ cre/s ( ,sgurr na ,bana*di* display on _! b>e black crags a di/9ct b$d$ /ructure4 ,on ! ea/ side ( ,lo* ,scavaig ! rock pres5ts a rudely-b&$ "*1 ! b&s or b$s be+ pil$ ov] ea* o!r f ! sea-level up to ! summits ( ! rugg$ precipices1 & dipp+ into ! hill at angles ( #be to #ce4 ,abundant dykes & ve9s ( v>i\s basic1 int]m$iate & acid rocks cut ?is /ructure4 ,! individual lay]s "h %[ sometimes ! wavy & puck]$ condition already ref]r$ to4 ,ev5 f a di/ance ! alt]nat+ light] & d>k] b&s c readily be se51 s t ?is /ructure1 ) ! v>iations 9 its incl9ation1 c be foll[$ f hill to hill 7,fig4 #cch74 ,! regul>ity ( ! arrangem5t1 h[ev]1 is (t5 less pron\nc$ on clos] inspection4 ,:ile ! gabbro is rudely dispos$ 9 ?ick b$s1 indicative ( diff]5t intrusive %eets or sills1 ) :i* ! b&+ is g5]ally p>allel1 consid]able irregul>ities may be obs]v$ 9 ! arrangem5t ( ! /ructure ( individual %eets4 ,^! %eets may be p>allel to ea* o!r1 & yet1 :ile 9 "s ! b&+ is tol]ably regul> 9 ! direction ( ! planes ( ! %eets1 9 o!rs x is mu* twi/$ or incl9$ at v>i\s angles4 ,illu/ration3 ,fig4 #ccg4--;,b&$ & d\bly-fold$ ,gabbro1 ,druim an ,eidhne1 #aj feet broad4 ,on ! we/ side ( ! ,coruisk riv] ! b&+ is v]tical2 s\?w>d f t /ream x incl9es slightly t[>ds ! s\?1 b soon aga9 becomes v]tical1 & cont9ues conspicu\sly s at ! junction ( ! gabbro ) ! ,torridon s&/ones & plateau-basalts on ! we/ side ( ,lo* ,scavaig4 ,?us1 in/ead ( be+ "o great eruptive boss1 ! gabbro ( ?is di/rict is 9 reality an exce$+ly complicat$ network ( sills1 ve9s & dykes4 ,:ile ! g5]al incl9ation ( ! b$d+ sometimes cont9ues uni=m 9 direction & am\nt f "o ridge to ano!r1 x is apt to *ange rapidly1 z if ! complex assemblage ( intrud$ masses _h be5 disrupt$ & _h subsid$ 9 diff]5t directions4 ,= example1 aft] ov]ly+ ! b$d$ basalts ( ! plateau all ! way f ,gl5 ,brittle to ! we/ side ( ,lo* ,scavaig1 ! gabbro desc5ds abruptly across ^! basalts & also across ! ,torridon s&/ones1 on :i* !y uncon=mably re/4 ,^! two gr\ps ( rocks are n only truncat$ by ! gabbro1 b are trav]s$ by ! intricate sy/em ( sills1 dykes & ve9s already ref]r$ to4 ,:]e x abuts aga9/ ! s&/ones & basalts 9 ,lo* ,scavaig1 ! gabbro is arrang$ 9 v]tical b&s ( diff]5t m9]al composition & texture4 ,mu* ( x is rem>kably co>se1 "s b&s display+ pyrox5e cry/als m ?an an in* 9 l5g?4 ,!re is no f9e-gra9$ selvage "h1 indicative ( m rapid cool+4 ,s co>se1 inde$1 is ! rock close up aga9/ ! s&/one1 t ! junction-l9e c h>dly be suppos$ to be ! normal contact ( ! intrusive rock4 ,?is inf]5ce is confirm$ by ! exi/5ce ( a s+ul> k9d ( breccia betwe5 ! gabbro & ! s&/ones4 ,x is a tumultu\s mass ( fragm5ts ( co>se & f9e gabbro1 ,torridon s&/one & %ale1 & plateau-basalts1 emb$d$ 9 a pale cry/all9e matrix ( f9e granul> granophyre2 ve9s f ?is acid intrusion run (f into ! gabbro on ! "o side z well z into ! ,torridon s&/ones on ! o!r4 ,x w\ld seem t ?is junction-l9e has be5 "o ( great movem5t1 t ! gabbro-%eets h subsid$ aga9/ a fault-wall ( plateau-basalt & ,torridon s&/one1 & t subsequ5tly an intrusion ( f9ely granul> granophyre has come up ! fissure1 involv+ 9 its asc5t fragm5ts ( all ! mat]ials ar\nd4 ,! rocks = a consid]able di/ance to ! s\? ( ! gabbro are int5sely alt]$4 ,! ,torridon s&/one has be5 s indurat$ z to pass into a blea*$ :ite qu>tzite1 :ile ! %ales int]/ratifi$ ) x h be5 conv]t$ into a k9d ( porcellanite4 ,b ! mo/ int]e/+ alt]ations are ^? to be obs]v$ 9 ! plateau-basalts1 :i* at a height ( ab\t #cjj feet above ! sea1 are to be se5 9 ne>ly horizontal %eets t lie imm$iately on ! upturn$ edges ( ! ,torridon s&/ones4 ,^! lavas h suff]$ great metamorphism1 to :i* m p>ticul> ref]5ce w be made 9 ,*apt] xlvi4 9 connection ) ! action ( ! granophyre4 ,:e!r ?is alt]ation has be5 produc$ by ! intrusion ( ! gabbro or ( "s conceal$ mass ( granophyre und]nea?1 ( :i* only project+ dykes & ve9s rea* ! surface1 mu/ rema9 a matt] ( d\bt4 ,on ! :ole1 z ! gabbro is "h und\bt$ly ?r[n aga9/ ! basalts & ,torridon s&/one by a fault1 x seems mo/ probable t ! *ange has be5 ma9ly due to ! influ5ce ( ! acid rock4 ,9 ! ,bla? ,bhe9n gr\p ( hills ! relations ( ! gabbro to ! b$d$ basalts h rec5tly be5 mapp$ 9 detail by ,mr4 ,h>k] dur+ ! progress ( ! ,geological ,survey ( ,skye4 ,he has obs]v$ t1 all[+ = irregul>ities ( =m1 ! mass ( gabbro obliquely ov]lies ! basalts z a great %eet1 n necess>ily due to a s+le intrusion1 :i* dips t[>ds ! we/4 ,he has f\nd ! rock to v>y f a co>se gabbro to a diabasic type1 & to v>y also 9 m9]alogical con/itution1 becom+ 9 places v ri* 9 oliv9e1 ?\gh ! b&$ /ructure is "h only exceptionally develop$4 ,nor? ( ,g>bh ,bhe9n ! gabbro is mu* cru%$ & ! outly+ pat* to ! nor? ( ,belig is 9 "p a cru%-breccia4 ,mr4 ,h>k] rem>ks t simil> brecciat$ /ructures are common among ! granophyres ( ! ,r$ ,hills1 & t x is sometimes difficult to di/+ui% _! /ructure f t ( ! true volcanic agglom]ates4 ,illu/ration3 ,fig4 #cch4--,sket* ( ,b&$ ,/ructure 9 ! ,gabbros ( ! hills at ! head ( ,lo* ,scavaig4 ,besides ! ma9 area ( gabbro 9 ,skye1 a great _m small deta*$ bosses1 sills & dykes lie fur!r ea/ on ! flanks ( ! ,r$ ,hills4 ,"o ( ! be/ m>k$ ( ^! deta*$ areas =ms a conspicu\s crag on ! ea/ side ( ,/ra? ,m1 imm$iately to ! nor? ( ,be9n na ,cro4 ,x consi/s ( b$s ( co>se gabbro1 ) o!rs ( dol]ite int]calat$ 9 an outli] ( ! plateau-basalts1 & is trav]s$ by ve9s f ! granophyre ( ! gl51 z well z by ! usual nor?-we/ basalt dykes 7,fig4 #cdi74 ,x appe>s to be a m>g9al portion ( ! ma9 gabbro area sep>at$ by ! intrusion ( ! great granitoid boss ( ! ,r$ ,hills4 ,on ! nor?-ea/]n side ( ,be9n na ,cailli* num]\s intrusive %eets ( gabbro & dol]ite trav]se ! qu>tzite & lime/one1 & ext5d d[n to ! sea-m>g9 9 ! ,s\nd ( ,scalpa4 ,!re is an important feature 9 ! ma9 gabbro area ( ,skye n yet cle>ly und]/ood1 & :i* only a m9ute & pati5t survey c elucidate4 ,?\gh ,i h f\nd among ! ,cuill9 ,hills no di/9ct pro( t ! mass ( gabbro ev] gave rise to dis*>ges ( mat]ial1 ei!r lava-=m or fragm5t>y1 :i* rea*$ ! surface1 ! gabbro area1 z already rem>k$1 conta9s unque/ionable evid5ce ( explosions & ! production ( pyrocla/ic masses4 ,among ! mora9e-m\nds ( ,h>ta ,corry1 blocks ( basalt-agglom]ate are /rewn ab\t1 full ( angul> fragm5ts ( alt]$ basalt1 sometimes highly amygdaloidal1 & also b\ld]s 9 :i* lumps ( co>se gabbro are envelop$ 9 a matrix ( f9] mat]ial4 ,i did n f9d ! p>5t rocks f :i* ^! glaci]-borne masses _h be5 d]iv$1 b !re c be no d\bt t !y exi/ among ! gabbro crags t surr\nd t deep gl54 ,ref]5ce has already be5 made to ! simil> rock f\nd 9 situ on ! opposite side ( ! ,cuill9 ridge at ! head ( ! great cauldron ( ,corry na ,crei*2 likewise to ! mass ( co>se agglom]ate :i* =ms a gr\p ( knolls & crags on ! ea/ side ( ,druim an ,eidhne above ! head ( ,gl5 ,sliga*an4 ,?is rock conta9s abundant blocks ( v>i\s slaggy lavas l ^? ( ! basalt-plateau1 & runs = "s di/ance along ! ea/]n limit ( ! gabbro1 betwe5 t rock & ! granophyre4 ,x is int]sect$ by num]\s basalt-ve9s4 ,mr4 ,h>k]1 z above m5tion$1 has rec5tly f\nd "s consid]able /rips ( agglom]ate :i*1 l t :i* ,i trac$ r\nd ! we/ side ( ,be9n ,de>g1 are int]pos$ betwe5 ! gabbro & ! bosses ( granophyre1 or lie at ! base ( ! volcanic s]ies 7p4 #bhd74 ,!re does n1 h[ev]1 appe> to be any evid5ce to connect ^! isolat$ masses ( agglom]ate ) ! ph5om5a att5d+ ! uprise ( ! gabbro4 ,!y seem to be m probably relat$ to ! plateau eruptions1 & may be comp>$ ) ^? ( ,/ra?1 ,ardnamur*an & ,mull 7pp4 #bgh1 #bhj1 #chd74 ,t ! huge gabbro mass ( ,skye1 besides invad+ & alt]+ ! b$d$ basalts1 may h communicat$ ev5tually ) ! surface1 & h giv5 rise to sup]ficial dis*>ges1 is n at all improbable1 b ( any su* outfl[s n a ve/ige appe>s n[ to rema94 ,we mu/ rememb]1 h[ev]1 t ! gabbro no d\bt 9 _m places f\nd its readie/ upw>d asc5t 9 v5ts belong+ to ! plateau-p]iod1 & t portions ( ! agglom]ates ( ^! e>li] v5ts may be expect$ to be f\nd involv$ 9 x1 z ! agglom]ate ( ! great v5t ( ,/ra? has be5 invad$ by ! granophyre4 ,,*apt] ,,xliv ,,! ,,bosses ,,& ,,%eets ,,( ,,gabbro ,,9 ,,! ,,di/ricts ,,( ,,rum1 ,,ardnamur*an1 ,,mull1 ,,/4 ,,kilda ,,& ,,nor?-,,ea/ ,,irel&4 ,,hi/ory ,,( ,,! ,,gabbro ,,intrusions #b4 ,! ,isl& ( ,rum ,! m\nta9s ( ! isl& ( ,rum1 ris+ z !y d f a wide expanse ( op5 sea1 pres5t "o ( ! mo/ prom95t & picturesque outl9es 9 ! ,we/ ,highl&s 7,map ,,vi474 ,m inaccessible ?an mo/ ( ! o!r p>ts ( ! volcanic region1 !y h be5 less visit$ by geologi/s4 ,!y 7 describ$ by ,maccullo* z compos$ ( v>ieties ( augite rock4 ,he notic$ 9 ?is rock a t5d5cy to ! same obscurely b$d$ disposition z is obs]v$ 9 o!r rocks ( ! trap family1 & f\nd at "o place t x assum$ a regul>ly b$d$ =m1 be+ dispos$ 9 ?9 horizontal /rata1 among :i* are int]pos$ equally ?9 b$s ( a rock resembl+ basalt 9 its g5]al *>act]s4#cej ,pr(essor ,judd repeats ,maccullo*'s obs]vation1 t ! great masses ( gabbro 9 ,rum (t5 exhibit t pseudo-/ratification s (t5 obs]v$ 9 igne\s rocks4 ,he reg>ds ^! masses1 l ^? ( ,skye & ,mull1 z repres5t+ ! core ( a volcano f :i* ! sup]ficial dis*>ges h be5 entirely remov$1 & he gives a section ( ! isl& 9 :i* ! gabbro is repres5t$ z an amorph\s boss s5d+ ve9s into a surr\nd+ mass ( granite4#cea ,9 a subsequ5t pap] he gave an excell5t detail$ acc\nt ( ! m9]alogical composition ( "s ( ! rem>kably v>i$ & beautiful basic rocks con/itut+ ! hills ( ,rum1 b add$ no fur!r in=mation reg>d+ ! geological /ructure ( ! isl&4#ceb ,footnote #cej3 ,we/]n ,isl&s1 i4 p4 #dhf4 ,footnote #cea3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxx4 p4 #bec4 ,footnote #ceb3 ,op4 cit4 xli4 7#ahhe7 p4 #ced4 ,see also 8 pap] 9 vol4 xlii4 ( ! same ,j\rnal4 ,ev5 f a di/ance ( eight or t5 miles1 ! hills ( ,rum are se5 to be obvi\sly built up ( successive ne>ly horizontal ti]s ( rock4 ,z ! summ] t\ri/ is c>ri$ pa/ ! isl&1 9 t wond]ful mov+ panorama reveal$ to him by ! swift /eam] ( mod]n days1 ^! great d>k cones rem9d him ( colossal pyramids1 & z ! ev]-v>y+ lights & %ad[s reveal m prom95tly ! alt]nate ne>ly level b>s ( crag & /ripes ( slope1 ! resemblance to ar*itectural =ms /amps ^! hills ) an individuality :i* /rikes 8 imag9ation & fixes itself 9 8 memory4 ,if *oice or *ance %\ld give him a ne>] view ( ! sc5e1 he w\ld n fail to notice t x is among ! nor!rn hills ( ! isl& t ! b$d$ "* is s conspicu\s1 & t x ceases to be prom95t 9 ! s\!rn heights1 ?\gh "h & !re1 z 9 ! upp] "p ( ,scuir na ,gillean1 x may 9 c]ta9 lights be detect$ ev5 f a di/ance4 ,cross+ ov] f ,eigg1 he w\ld recognize ea* ( ! features repres5t$ 9 ! sket* reproduc$ 9 ,fig4 #cci4 ,along ! %ore1 r$ s&/ones rise 9 nak$ cliffs1 f ! top ( :i* ! gr\nd slopes upw>d 9 br[n moors to ! b>e rocky declivities4 ,a deep valley 7,gl5 ,dibidil7 is se5 to run into ! he>t ( ! hills1 betwe5 ! b$d$ gr\p to ! nor? & ! /ructureless gr\p to ! s\?4 ,if ! wea!r is fav\rable1 "s eight or m prom95t p>allel b>s ( rock may be c\nt$ on ! two high] cones to ! "r4 ,^! b>s are n q level1 b slope g5tly f "r to left4 ,!y rem9d "o ( ! t]rac$ basalts ( ! plateaux1 b pres5t a massiv5ess & a bread? ( int]v5+ b>e talus-slope su* z are n usual among ^? rocks4 ,illu/ration3 ,fig4 #cci4--,outl9e ( ! ,hills ( ! ,isl& ( ,rum1 sket*$ f ne> ! ,isle ( ,eigg4 ,nor is ?is impression ( regul>ity & b$d$ arrangem5t less5$ :5 we actually climb ! slopes ( ! hills4 ,i _h = ye>s be5 famili> ) ! outl9es ( ,rum z se5 f a di/ance1 & _h sket*$ !m f e side1 b ,i %all nev] =get ! surprise & pleasure :5 my fir/ asc5t ( ! cones reveal$ to me ! mean+ ( ^! p>allel ti]s ( rock4 ,i f\nd x to be ! /ructure ( ! ,cuill9 ,hills repeat$1 b ) "s m9or diff]5ces :i* are ( int]e/1 inasmu* z !y enl>ge our conceptions ( ! process by :i* ! gabbro-bosses 7 =m$4 ,! nor!rn half ( ! isl& ( ,rum consi/s almo/ entirely ( r$ s&/one1 :i*1 z already /at$1 is a cont9uation ( ! same =mation 7,torridonian7 s well develop$ 9 ! s\?-ea/ ( ,skye1 ,applecross & ,lo* ,torridon1 & traceable betwe5 ! ,ar*an gneiss & ! ,cambrian /rata up z f> z ,cape ,wra?4 ,! s&/ones1 ?\gh full ( false b$d+1 %[ q di/9ctly _! true /ratification1 :i* is incl9$ ) s+ul> p]si/5ce t[>ds ,w4,n4,w41 at angles av]ag+ f #ae to #bj4 ,if !y are n repeat$ by folds or faults1 !y mu/ rea* 9 ?is isl& a ?ickness ( "s #aj1jjj feet4 ,_! r$ or r p9ki% t9t seems ma9ly to arise f ! p9k felsp> s abundant 9 !m1 = 9 _m places !y really consi/ ( a k9d ( arkose4 ,pebbly b&s ) r\nd$ pieces ( qu>tz are ( common occurr5ce ?r\gh\t ! :ole =mation4 ,dykes & ve9s ( basalt are pr(usely abundant4 ,sometimes ^! run ) ! b$d+1 & might at a di/ance be tak5 = d>k lay]s among ! p9k s&/ones4 ,!y (t5 also /rike obliquely up ! face ( ! cliffs l ribbons4 ,b1 not)/&+ _! app>5t cont9uity1 !re c be no d\bt t ^! s&/ones h suff]$ f ^? p[]ful t]re/rial di/urbances :i* h affect$ all ! old] rocks ( ! ,nor?-,we/ ,highl&s4 ,on ! we/ side1 :]e !y plunge /eeply into ! sea1 !y h und]gone a *ange into f9e lam9at$ rocks1 :i* might at fir/ be mi/ak5 = %ales1 b :i* owe _! fissility to %e>+ movem5ts4 ,along _! s\!rn bord]1 f a po9t on ! ea/ coa/ ne> ,bagh-na-h-,uamha1 s\? ( ,lo* ,scresort1 to ! head ( ,kilmory ,gl51 !y are abruptly truncat$ aga9/ a gr\p ( d>k1 flaggy & fissile s*i/s & f9e qu>tzites or grits1 :i* 9 "s places are black & massive l basalt1 & 9 o!rs are associat$ ) co>se grey gneiss4 ,t "s ( ^! rocks are portions ( ! ,lewisian s]ies c h>dly be d\bt$1 & _! /ructure & relations are probably repetitions ( ^? betwe5 ! ,lewisian gneiss & ,torridon s&/one ( ,sleat 9 ,skye4 ,i f\nd also on ! nor!rn slopes ( ,gl5 ,dibidil a pat* ( mu* alt]$ grey & :ite lime/one or m>ble1 :i* rem9d$ me ( ! ,cambrian lime/one ( ,skye4 ,! r$ s&/ones 9 a m or less alt]$ condition are prolong$ to ! s\?-ea/ promontory ( ! isl&4 ,9 pass+ ov] ! zone ( ^! m anci5t rocks1 we f9d !m to pres5t increas+ signs ( alt]ation z !y are trac$ up ! slopes t[>ds ! great c5tral mass ( erupt$ mat]ial4 ,! p9k s&/ones gradually lose _! *>act]i/ic t9t1 & gr[ mu* h>d] & m compact1 :ile ! ve9s & dykes ( basalt & %eets ( dol]ite int]sect+ !m increase 9 numb]4 ,! zone ( black compact qu>tzite1 :i* lies to ! s\? ( ! s&/ones1 & :i* at "o po9t rem9ds u ( basalt1 at ano!r ( ! fl9ty slate ( ! s*i/ose s]ies1 likewise displays increas+ induration4 ,its b$d+1 n always to be detect$1 is (t5 v]tical & crumpl$4 ,b ! mo/ rem>kable po9t 9 its /ructure is ! int]calation 9 x ( b&s ( breccia4 ,^! v>y f less ?an an in* to sev]al y>ds 9 diamet]2 !y run mo/ly ) ! b$d+1 b occasionally across x4 ,! /ones 9 !m are fragm5ts ( ! surr\nd+ rock emb$d$ 9 a matrix ( ! same mat]ial1 b also ) pieces ( a some:at co>s] grit or qu>tzite4 ,a b& ( co>se breccia =ms ! s\!rn limit ( ?is zone along ! nor!rn base ( ,b>keval & ,allival4 ,9 g5]al "* x resembles ! ?9n] seams ( ! same mat]ial j ref]r$ to4 ,! matrix s closely agrees ) ! black fl9ty qu>tzite1 t b = ! includ$ /ones x c\ld h>dly be di/+ui%$2 s greatly has ! mass be5 indurat$ t ! /ones seem to %ade (f into ! re/ ( ! rock4 ,b "h & !re its true brecciat$ nature is conspicu\sly reveal$ by prom95t blocks ( h>d5$ s&/one4 ,?is b& ( breccia mu/ 9 "s places be #aej or #bjj feet broad4 ,x has no di/9ct b$d+1 b seems to lie z a highly incl9$ b$ dipp+ into ! hill4 ,x may possibly be a cru%-breccia belong+ to a p]iod e>li] ?an ! volcanic eruptions4 ,x is at once succe$$ by a black fl9ty felsite l t ( ,mull4 ,! gr\ndmass ( ?is rock1 s ?ickly p[d]$ ) magnetite gra9s z to be almo/ opaque "u ! microscope1 displays good fl[-/ructure r\nd ! turbid cry/als ( or?oclase & ! cle> granules ( qu>tz4 ,fur!r up ! hill1 ! rock becomes light] 9 col\r & less fl9ty 9 texture--a *ange :i* is f\nd to arise f m complete devitrification1 ! gr\ndmass hav+ become a cry/all9e granul> aggregate ( qu>tz & felsp> ) scatt]$ porphyritic cry/als ( ^! m9]als 7microgranite74 ,9 "s places1 ! felsite incloses fragm5ts ( o!r rocks4 ,a specim5 ( ?is k9d1 tak5 f ! head ( ,coire ,dubh1 %[s "u ! microscope a br[n micro-felsitic gr\ndmass1 ) cry/als ( felsp> & augite1 inclos+ a piece ( basalt1 compos$ ( f9e la?s ( plagioclase1 abundant magnetite & a small] proportion ( granules ( augite4 ,illu/ration3 ,fig4 #cdj4--,view ( ,allival1 ,rum1 sket*$ f ! base ( ! nor?-ea/ side ( ! cone4 ,?is b& ( felsite & microgranite may be trac$ cont9u\sly f ,lo* ,ga9mi* along ! base ( ,b>keval & ,allival1 & simil> rocks appe> at int]vals on ! same l9e r\nd ! ea/]n base ( ! hills4 ,imm$iately above ?is belt ( felsitic protrusions comes ! great body ( gabbro4 ,x w be obs]v$ t "h1 z 9 ,skye1 ! base ( ! gabbro mass pres5ts a horizon on :i* injections ( acid rocks h be5 p>ticul>ly abundant4 ,:e!r ! breccias be reg>d$ z ! result ( e>li] rock-cru%+s1 or z due to volcanic explosions dur+ ! ,t]ti>y p]iod1 !y are evid5tly old] ?an ! eruption ( ! gabbros4 ,9 t respect !y may be comp>$ ) ! agglom]ates ?r\gh :i* ! y\nge/ eruptive bosses ( ,skye h made _! way2 b _! compon5t mat]ials h be5 d]iv$ f ! surr\nd+ plat=m ( anci5t rocks1 & n f subt]ranean lavas4 ,illu/ration3 ,fig4 #cda4--,section ( foliat$ gabbros 9 ! ,t]ti>y volcanic s]ies ( ,allival1 ,rum4 a1 massive gabbro ) rude lam9ation p>allel to b$d+1 only se5 9 "s wea!r$ surfaces2 b1 lam9at$ troctolite2 c1 massive co>sely cry/all9e gabbro rudely lam9at$4 ,= my pres5t purpose1 h[ev]1 ! *ief po9t ( importance is ! /ructure ( ! gabbro mass t spr+s f t plat=m into ! great conical hills ( ,rum4 ,! accompany+ sket* 7,fig4 #cdj7 w convey a bett] idea ( ?is /ructure ?an a m]e description4 ,at ! base1 imm$iately above ! felsite j ref]r$ to1 b$d$ dol]ites make _! appe>ance1 mu* int]sect$ ) ve9s f ! silice\s rock4 ,ve9s & dykes ( basalt also cut all ! rocks "h1 ! newe/ be+ ^? :i* run 9 a nor?-we/ direction4 ,! l[e/ %eets ( dol]ite are succe$$ by ov]ly+ sills ( co>s] dol]ites1 gabbros1 troctolites1 etc41 :i* are z regul> 9 _! ?ickness & cont9uity z ! ord9>y basalts ( ! plateaux4 ,! b& ( light-col\r$ troctolite1 9 p>ticul> 7,fig4 #cda71 ab\t #bj to #cj feet ?ick1 :i* has be5 already ref]r$ to = its rem>kable lam9> /ructure1 c be foll[$ = "s di/ance along ! base ( ! hill z a m>k$ project+ esc>pm5t4 ,?is rock at once arre/s att5tion by its platy or fissile /ructure1 p>allel to ! b$d+-surfaces ( ! %eet4 ,inde$ h&-specim5s ( x1 z ,i h said1 might readily pass = pieces ( s*i/ose lime/one1 especially if tak5 f ! upp] "p4 ,x consi/s ( successive lay]s1 :i* on ! wea!r$ surface divide x into b$s almo/ z regul> z ^? ( a flag/one1 ea* b$ be+ fur!r sep>at$ into lam9 m>k$ (f by ! d>k] & light] t9ts ( _! m9]al con/itu5ts4 ,! d>k] lay]s consi/ ( oliv9e1 & ! light] ( plagioclase4 ,?is segregation "h & !re takes ! =m ( r\nd$ masses1 :]e ! m9]als are m indef9itely ga!r$ toge!r4 ,! aff9ity ( ! rock ) intrusive %eets is fur!r display$ by ! occurr5ce ( abundant nut-l aggregates ( pale gre5 oliv9e4 ,exam9$ "u ! microscope1 fl[-/ructure is admirably se51 ! la?-%ap$ felsp>s be+ drawn out p>allel to ! planes ( movem5t1 & giv+ !reby ! peculi>ly s*i/ose /ructure :i* is s deceptive4 ,! massive & co>sely cry/all9e gabbros bel[ & above ?is troctolite are all m or less affect$ by ! same lam9> /ructure4 ,"s ( ^? 9 high] p>ts ( ! m\nta9 are q massive 9 "p1 b also include b&s ( lam9ation4 ,b&+ l t ( ! ,skye gabbros is g5]ally develop$ among !m1 ! individual b&s v>y+ f less ?an an in* to a foot or m 9 ?ickness4 ,?is /ructure1 l ! lam9ation1 is p>allel to ! g5]al b$d+ ( ! %eets4 ,z 9 ! ,cuill9 ,hills1 ! b&s diff] f ea* o!r 9 ! relative proportions ( ! con/itu5t m9]als1 especially ! pr$om9ant pyrox5e & oliv9e4 ,! cry/als or cry/all9e aggregates are (t5 f a qu>t] ( an in* to an in* 9 diamet]1 & 9 ^! l>ge =ms are cr[d$ toge!r 9 c]ta9 b&s4 ,magnetite1 on ! :ole1 is r less conspicu\s ?an 9 ! ,cuill9 gabbro3 at lea/1 x is n s prom95tly aggregat$ 9 special lay]s4 ,9 "o or two in/ances ,i h obs]v$ curvature ( ! b&+1 b no example s /rik+ z t cit$ f ! ,cuill9 area 7,fig4 #ccg74 ,on wea!r$ surfaces1 :]e ! felsp>s decay into a creamy :ite & ! f]ro-magnesian m9]als assume t9ts ( gre51 br[n & r$1 ! resemblance ( ! rocks to s*i/s is /rik+4 ,?is ext]nal lik5ess is comb9$ ) a t5d5cy to split into ?9 plates p>allel to ! lam9ation1 :i* /ill fur!r increases _! s*i/ose appe>ance4 ,?\gh less develop$ ?an 9 ,skye1 ! b&+ appe>s to be ( ! same k9d & orig92 b 9 ,rum x is comb9$ ) ! rem>kable lam9ation above m5tion$1 produc$ by ! arrangem5t ( ! compon5t m9]als ) _! long] axes p>allel to ! planes ( b$d+1 z 9 fl[-/ructure--a comb9ation :i* ,i h n yet obs]v$ 9 ,skye4 ,! b$d$ arrangem5t ( ! gabbros ( ,rum1 s conspicu\s 9 ! great ea/]n cones 7,figs4 #cci & #cdj71 is emphasiz$ by ! fact t "s %eets1 ( a m durable k9d1 /& out boldly z prom95t ribs1 :ile ! s(t] crumble into a k9d ( s&1 :i* =ms talus-slopes betwe5 ! o!rs4 ,alt]nations ( ?is nature are cont9u$ up to ! v top ( ! m\nta9s4 ,! b$s are ne>ly flat1 b dip slightly into ! int]ior or t[>ds ! s\?-we/4 ,on ! we/ side ( ! isl& also1 beyond ,lo* ,sga?aig1 a di/9ct b$d+ may be trac$1 ! incl9ation be+ "h once m inw>ds or to ! ea/4 ,b f ,gl5 ,h>ris & ! base ( ,askival ?is /ructure becomes less m>k$1 & gradually disappe>s4 ,!re is ?us a c5tral or s\!rn m amorph\s region1 :ile r\nd ! m>g9 t[>ds ! nor? & ea/ ! rock appe>s 9 frequ5t alt]nat+ b$s4 ,x is cle> t 9 ! broad features ( _! ar*itecture ! hills ( ,rum foll[ closely ! plan %[n 9 ! ,cuill9 ,hills ( ,skye4 ,b1 un=tunately1 9 ! =m] isl& d5udation has gone s f> t no connection c be trac$ on ! gr\nd betwe5 ! gabbros & ! plateau-basalts4 ,z already /at$1 ! latt] rocks h be5 almo/ entirely /ripp$ (f f ! plat=m ( s&/ones & s*i/s :i* !y und\bt$ly at "o "t cov]$1 & ! few outli]s ( !m t rema9 lie at "s little di/ance f ! m>g9 ( ! gabbro area 7ante1 p4 #baf74 ,nev]!less1 we are n )\t "s indications ( !m und]nea? ! gabbros4 ,i h allud$ to ! basalts t lie at ! base ( ! ea/]n cones4 ,z we foll[ ! bottom ( ! gabbro s\?w>d r\nd ! flanks ( ! hills1 dull compact black %att]y basalts1 ) a :ite cru/1 appe> f "u ! m cry/all9e %eets4 ,^! at once rem9d "o ( ! alt]$ basalts ( ,skye & ,mull4 ,on ! we/ side also1 b$s ( basalt em]ge f "u ! gabbro1 b !y h be5 s ve9$ & indurat$ by ! granophyre ( t di/rict1 t _! relations to ! gabbro are some:at obscur$4 ,if we c\ld re/ore ! lo/ portions ( ! plateau1 ,i believe we %\ld f9d ! gabbros ( ,rum re/+ on "p ( ! volcanic plateau1 & "s ( ! gabbro-b$s prolong$ z sills betwe5 ! %eets ( basalt4 #c4 ,! ,gabbro ( ,ardnamur*an ,! promontory ( ,ardnamur*an reveals z cle>ly z ! flanks ( ! ,cuill9 ,hills1 ?\gh 9 a less impos+ way1 ! relations ( ! gabbros to ! plateau-basalts 7,map ,,vi474 ,f ! s\!rn %ore at ,kil*oan to ! nor!rn %ore at ,kilmory1 b$d$ basalts1 ( ! usual type1 amygdaloidal & compact1 wea!r+ into br[n soil1 may be foll[$ along ! ea/]n slopes ( ! hills1 re/+ ^u ! s*i/s & ,jurassic s]ies ( we/]n ,argyle%ire4 ,^! rocks are a cont9uation ( ^? t cap ! ridges fur!r to ! s\?-ea/ & cross ,lo* ,sun>t into ,morv54 ,!y dip we/w>ds1 & foll[$ upw>ds 9 t direction1 !y soon pres5t ! usual m>ks ( alt]ation4 ,!y wea!r ) a :ite cru/ & become indurat$ & spl9t]y4 ,%eets ( dol]ite ) _m ve9s & dykes ( basalt run betwe5 & across !m4 ,b&s ( gabbro make _! appe>ance1 & ^!1 z we advance we/w>ds1 increase 9 numb] & 9 co>s5ess ( gra9 until ?is rock1 9 its rudely b$d$ =m1 con/itutes practically ! :ole ( ! promontory f ,meall nan ,con to ! light-h\se4 ,_m admirable sections may be se5 on ! coa/-cliffs & 9 ! rugg$ int]ior1 %[+ ! irregul> b$d+ ( ! gabbro1 & h[ prone ?is rock is to develop its compon5t m9]als 9 b&s or ribbons1 sometimes made up ( l>ge cry/als1 z 9 ,skye1 ,rum & ,mull4 #d4 ,! ,gabbro ( ,mull ,9 ! isl& ( ,mull1 ! conclusions to :i* ! geology ( ! o!r volcanic di/ricts leads u z to ! position ( ! gabbros 9 ! s]ies ( volcanic ph5om5a1 are fur!r confirm$4 ,! fir/ geologi/ :o appe>s to h obs]v$ ! relation ( ^! rocks 9 t isl& 0 ,jameson1 :o class$ !m "u ! old "n ( gre5/one1 includ+ 9 ! same designation rocks n[ t]m$ dol]ites & gabbros4 ,he asc5d$ "o ( ! hills above ,lo* ,don1 probably ,ma9nir nam ,fiadh 7#bdhc feet71 :i* he f\nd to consi/ ( /rata ( basalt & gre5/one1 ) "s basalt-breccia or tuff & a capp+ ( basalt4 ,he speaks ( ! s+ul> scorifi$-l aspect ( ! wea!r$ gre5/one--a description :i* applies to "s ( ! co>s] gabbro b&s ( t locality4 ,b he appe>s to h recogniz$ ! g5]al b$d$ arrangem5t ( ! rocks up ev5 to ! summit ( ! hill4#cec ,footnote #cec3 ,m9]alogy ( ! ,scotti% ,isles i4 p4 #bje4 ,x 0 n1 h[ev]1 until ! visit ( ,pr(essor ,zirkel 9 #ahfh1 t ! true petrographical *>act]s ( ! gabbro ( ,mull 7 recogniz$4 ,?is obs]v] rem>k$ t ! rock is regul>ly int]/ratifi$ ) ! basalt4#ced ,pr(essor ,judd1 z already /at$1 has suppos$ ! gabbros to be ! deep-seat$ portion ( ! masses :i* :5 p\r$ out at ! surface became ! plateau-basalts1 & he repres5ts !m 9 8 map & sections ( ,mull z ramify+ ?r\gh ! granitic rocks4#cee ,footnote #ced3 ,zeits*4 ,deuts*4 ,geol4 ,gesells*4 xxiii4 7#ahga7 p4 #eh4 ,footnote #cee3 ,qu>t4 ,j\r4 ,geol4 ,soc4 xxx4 7#ahgd74 ,9 ,mull ! disposition ( ! gabbro 9 b$s1 %eets or sills is well display$1 = !re is "h no great c5tral complicat$ mass ( int]lac+ b&$ & amorph\s %eets4 ,we h se5 t a high] gr\p ( plateau-basalts has surviv$ 9 ?is isl& bett] ?an 9 ! o!r plateaux1 & x w\ld seem t d5udation has n yet succe$$ "h 9 cutt+ d[n s deeply into ! gabbro core z 9 ,skye1 ,rum & ,ardnamur*an4 ,only ! upp] or out] fr+e ( intrusive %eets among ! b$d$ basalts has be5 laid b>e4 ,! di/rict )9 :i* ?is fr+e may be obs]v$ is tol]ably well-def9$ by ! diff]5ce ( cont\r betwe5 ! long t]rac$ upl&s ( ! ord9>y basalts & ! m conical =ms ( ! s\!rn gr\p ( gabbro hills betwe5 ,lo* na ,keal & ,lo* ,spelve4 ,! numb] & ?ickness ( ! gabbro-%eets increase z we proce$ inw>ds f ! basalt-plateau4 ,^! %eets are specially prom95t along ! high] p>ts ( ! ridge t runs nor?w>ds f ! nor!rn end ( ,lo* ,spelve1 & along ! we/ side ( ,gl5 ,=sa4 ,b !y swell out into ! ?icke/ mass 9 ! s\?-we/]n "p ( ! hilly gr\nd1 :]e1 f above ,craig1 9 ,gl5more1 !y cross t valley1 & =m ! rugg$ ridge t rises into ,b5 ,buy 7#bced feet71 & /ret*es ea/w>d to ne> ,ard>a 7,map ,,vi474 ,x is 9 ?is s\!rn mass t ! ,mull gabbro approa*es ne>e/ 9 g5]al *>act]s to t ( ,skye4 ,b ev5 "h its true int]calation above a great mass ( b$d$ basalt may readily be asc]ta9$ 9 any ( ! num]\s rav9es & rocky declivities4 ,"o ( ! be/ l9es ( section = exhibit+ ! relations ( ! rocks is ! declivity to ! we/ ( ,b5 ,buy & ,lo* ,fhu>an4 ,asc5d+ f ! we/ side1 we walk ov] successive l[ esc>pm5ts & t]races ( ! plateau-basalts ) a g5tle incl9ation t[>ds nor?-ea/ or ea/4 ,^! rocks wea!r 9 ! usual way1 "s into a br[n loam1 o!rs into sph]oidal exfoliat+ masses4 ,b z we advance uphill !y gradually assume ! peculi> indurat$ %att]y "* already ref]r$ to4 ,! s(t e>?y amygdaloids become dull spl9t]y rocks1 9 :i* ! amygdales are no long] %>ply def9$ f ! matrix1 b r seem to %ade (f into x1 sometimes ) a bord] ( int]lac+ fibres ( epidote4 ,! compact basalts h und]gone less *ange1 b !y too h become indurat$1 & g5]ally assume a :ite or grey cru/1 & none ( !m wea!r out into column> =ms4 ,/r+s & ?reads full ( epidote run ?r\gh mu* ( ^! alt]$ rocks4 ,abundant granophyric & felsitic ve9s trav]se !m4 ,%eets ( dol]ite likewise make _! appe>ance betwe5 ! basalts1 foll[$ fur!r up ! slope by %eets ( gabbro until ! latt] =m ! ma9 body ( ! hill4 ,on ! nor? side ( ! same ridge simil> evid5ce is obta9able1 ?\gh some:at complicat$ by ! injections ( granophyric & felsitic ve9s & bosses1 to :i* m detail$ ref]5ce w aft]w>ds be made4 ,b ! alt]$ basalts ) _! amygdaloidal b&s & _! int]calat$ basalt-tuffs & breccias1 c be foll[$ f ! bottom ( ! gl5 up to a height ( "s #agjj feet1 above :i* ! ma9 gabbro mass ( ,b5 ,buy sets 94 ,_m m9or %eets ( dol]ite & gabbro make _! appe>ance along ! side ( ! hill be=e ! *ief ov]ly+ body ( ! rock is rea*$4 ,"s ( ^! c be di/9ctly se5 break+ across or end+ (f betwe5 ! b$d$ basalts :i* "h dip g5tly into ! hill 7,fig4 #cdb74 ,a conspicu\s b& ( co>se basalt-agglom]ate1 conta9+ blocks ( compact & amygdaloidal basalt a y>d or m 9 diamet]1 %[s by ! excessive induration ( its dull-gre5 matrix ! g5]al alt]ation :i* ! rocks ( ! basalt-plateau h "h und]gone4 ,an almo/ incr$ible numb] ( ve9s ( f9e basalt1 porphyry & felsite has be5 inject$ into ^! rocks--a /ructure :i* is precisely a c\nt]p>t ( :at occurs "u ! ma9 body ( gabbro 9 ,skye1 ,ardnamur*an & ,rum4 ,illu/ration3 ,fig4 #cdb4--;,alt]$ ,plateau-,basalts invad$ by ,gabbro1 & ) a ,dyke ( prismatic ,basalt cutt+ bo? rocks1 nor? slope ( ,b5 ,buy1 ,mull4 a a1 amygdaloidal basalt1 mu* alt]$2 b1 gabbro2 c1 f9ely prismatic basalt4 ,! gabbro mass ( ! ,b5 ,buy ridge is ?us und\bt$ly a huge ov]ly+ %eet1 :i* probably rea*es a ?ickness ( at lea/ #hjj feet4 ,x seems to desc5d r across ! b$d+ into ! holl[ ( ,gl5 ,m1 & possibly its ma9 pipe ( supply lay 9 t direction4 ,be+ enorm\sly ?ick] ?an any o!r %eet 9 ! isl&1 x exhibits ! cry/all9e peculi>ities :i* are s well develop$ 9 ! c5tral portions ( ! l>g] bosses ( gabbro4 ,x pres5ts m co>sely cry/all9e v>ieties ?an appe> 9 ! ?9n] %eets1 "s portions %[+ cry/als ( diallage & felsp> upw>ds ( an in* 9 l5g?4 ,x likewise conta9s admirable examples ( b&$ /ructure1 :i*1 z 9 ,skye & else:]e1 is be/ develop$ :]e ! texture becomes especially co>se4 ,ve9s or b&s1 9 :i* ! con/itu5t m9]als h cry/alliz$ out 9 m def9ite & conspicu\s =ms1 "h & !re succe$ ea* o!r s quickly z to imp>t a b$d$ or foliat$ look to ! body ( rock1 recall+1 z 9 ,skye1 ! aspect ( "s co>sely cry/all9e granitoid gneiss4 ,9 ^! respects ! ,mull gabbro closely resembles t ( ! ,cuill9 ,hills4 ,occasionally1 on ! expos$ faces ( crags1 portions ( su* b&s or ve9s are se5 to be deta*$ & envelop$ 9 a f9] surr\nd+ matrix4 ,! ?ick belts or b&s ( co>s] & f9] texture alt]nate1 & give an appe>ance ( b$d+ to ! mass4 ,nev]!less !y are really intrusive sills1 :i* run g5]ally p>allel ) b$s ( f9] gabbro or ) %eets ( highly indurat$ basalt1 t may be deta*$ portions ( ! ord9>y rocks ( ! plateau4 ,! ?ick %eet ( ,b5 ,buy1 l ! mass ( ! ,cuill9 ,hills1 is ?us ! result n ( "o b ( _m uprises ( gabbro4 ,( ! ?9n] %eets ( dol]ite & gabbro 9 ,mull little ne$ "h be said4 ,i h ref]r$ to _! great abundance 9 ! range ( ea/]n hills t rise f ! ,s\nd ( ,mull betwe5 ,lo* ,spelve & ,fi%ni% ,bay4 ,?\gh obvi\sly intrusive1 !y lie on ! :ole p>allel to ! b$d+ ( ! basalts4 ,! latt] rocks exhibit ! usual dull indurat$ %att]y "* :i* !y assume :]e l>ge bosses ( gabbro h invad$ !m1 & :i* gradually disappe>s z we foll[ !m d[n hill away f ! intrusive %eets to ! %ores ( ! ,s\nd4 ,!y dip t[>ds ! c5tre ( ! hill gr\p1 t is1 to s\?-we/ 9 ! ridge ( ,ma9nir nam ,fiadh1 ,dn da ,ghaoi!1 & ,be9n ,meadhon1 ! angle increas+ s\?w>ds to #ae-bj1 & at ! s\? end rea*+ z mu* z #ce-dj4 ,"s f9e crags ( gabbro & dol]ite =m a prom95t spur on ! ea/ side ( ! ridge ( ,b5 ,talaidh1 9 ! upp] "p ( ,gl5 ,=sa4 ,^! consi/ ( successive %eets b$d$ ) ! basalts1 & dipp+ s\?-we/4 ,a l>ge %eet /&s out conspicu\sly on ! nor? front ( ,b5 ,m1 ly+ at ! base ( ! pale lavas1 & imm$iately above ! ord9>y basalts4 ,x circles r\nd ! f9e corry betwe5 ,b5 ,m & ,a',*io*1 "s ( its domes be+ !re beautifully ice-worn4 ,?is is ! highe/ plat=m to :i* ,i h satisfactorily trac$ any ( ! intrusive %eets ( ,mull4 ,ano!r dyke-l mass em]ges f b5ea? ! talus slopes ( ,a',*io*1 on ! s\!rn side1 & runs ea/w>d across ! col betwe5 ! ,cla*aig ,gl5 & ,lo* ,scrida94 #e4 ,! ,gabbros ( ,/4 ,kilda & ,nor?-ea/ ,irel& ,sixty miles to ! we/w>d ( ! ,out] ,hebrides lies ! lonely gr\p ( islets ( :i* ,/4 ,kilda is ! *ief4 ,z ! ma9 feature ( geological int]e/ 9 ?is gr\p is ! relation ( ! acid protrusions to ! o!r rocks1 ! acc\nt ( ! geology w be m appropriately giv5 z a :ole 9 ,*apt] xlvii4 ,i ne$ only rem>k "h t ! pr$om9ant rocks ( ^! isl&s are d>k basic masses1 *iefly v>ieties ( gabbro1 b includ+ also dol]ites & basalts4 ,reasons w be aft]w>ds br\ght =w>d = reg>d+ ^! rocks z p>ts ( ! ,t]ti>y volcanic s]ies4 ,!y pres5t a close p>allel to ! gabbros & associat$ rocks ( ,skye4 ,b 9 "o important respect !y /& alone4 ,no c]ta9 trace rema9s ( any basalt-plateau at ,/4 ,kilda su* z ^? ?r\gh :i* ! gabbros ( ,skye1 ,mull & ,ardnamur*an h be5 inject$4 ,9 reg>d to _! mode ( production !y h d\btless be5 intrud$ at "s consid]able dep? b5ea? ! surface4 ,b no relic appe>s to h surviv$ ( ! ov]ly+ cov] ( rock "u :i* !y consolidat$1 & into :i* !y 7 inject$4 ,9 ! rem>kable volcanic di/rict ( ! nor?-ea/ ( ,irel& a s]ies ( basic rocks appe>s1 :i* 9 its mode ( occurr5ce & its relation to ! o!r memb]s ( ! s]ies pres5ts _m po9ts ( resemblance to ! gabbros ( ! ,inn] ,hebrides4 ,! ,iri% gabbros are well develop$ 9 ! ,c>l+=d di/rict1 :]e !y =m intrusive bosses & %eets :i* h be5 erupt$ ?r\gh ! ,palozoic rocks 7,map ,,vii474 ,!y are !mselves pi]c$ by lat] masses ( granophyre & o!r acid rocks4 ,fur!r ref]5ce w be made to ^! gabbros 9 lat] pages1 :]e an acc\nt w be giv5 ( ! granite masses ( ,m\rne1 ,b>navave & ,slieve ,gullion4 99 99 99 99 99 ,x is int]e/+ to obs]ve t1 :ile 9 ,/4 ,kilda no relic ( any basaltic plateau has be5 pres]v$1 9 ! ,f>oe ,isl&s1 on ! o!r h&1 no sign has be5 reveal$ by d5udation t ! volcanic plateau ( t region is pi]c$ by any eruptive core ( gabbro or ( granophyre4 ,dur+ my cruises r\nd ^! isl&s & ?r\gh _! *annels1 ,i 0 ev] on ! outlook = any diff]5ce 9 topography t might indicate ! pres5ce ( "s eruptive boss l ! gabbro & granophyre masses ( ! ,inn] ,hebrides4 ,b no?+ ( t nature c\ld be disc]n$4 ,ev]y:]e ! long level l9es ( ! b$d$ basalts 7 se5 m\nt+ up to ! cre/s ( ! ridges & ! tops ( ! highe/ peaks4 ,?\gh ,i _c ass]t t no intrusions ( gabbro or ( granophyre exi/ among ! ,f>oe ,isl&s1 ,i feel confid5t t any su* masses :i* may appe> at ! surface mu/ be ( q insignificant dim5sions1 & d n make ! important feature 9 geology & topography :i* !y d among ! ,inn] ,hebrides4 ,x is1 ( c\rse1 possible t1 va/ z ! d5udation ( ^! isl&s has und\bt$ly be51 x has n yet tr5*$ ! plateau deeply en\gh to expose any great intrusive bosses & sills :i* may und]lie & invade ! basalts4 iv4 ,,hi/ory ,,( ,,! ,,gabbro ,,intrusions ,we are n[ 9 a position to draw1 f ! obs]vations :i* h be5 giv5 9 ?is & ! prec$+ *apt] reg>d+ ! diff]5t areas ( gabbro 9 ! ,t]ti>y volcanic region ( ,brita91 "s g5]al conclusions ) respect to ! type ( geological /ructure & ! phases ( volcanic en]gy :i* !y illu/rate4 #a4 ,no evid5ce exi/s to %[ t ! masses ( gabbro ev] communicat$ directly ) ! surface4 ,!y nev] exhibit ! cellul>1 slaggy & o!r /ructures s *>act]i/ic ( surface-fl[s4 ,!y are1 on ! :ole1 free f includ$ pyrocla/ic mat]ial1 ?\gh masses ( agglom]ate are enclos$ 91 & h probably be5 invad$ by1 ! gabbro ( ! ,cuill9 ,hills4 ,if ! gabbro-bosses ev] 7 cont9u\s ) %eets ( rock emitt$ above gr\nd1 all su* upw>d cont9uations h be5 entirely remov$4 ,9 any case1 we may be q c]ta9 t 9 an outbur/ at ! surface1 ! rock w\ld n h appe>$ 9 ! =m ( a co>sely cry/all9e or granitoid gabbro4 #b4 ,! cry/all9e /ructures ( ! gabbros po9t unmi/akably to sl[ cool+ & consolidation at "s dep? b5ea? ! surface4 ,! mo/ co>sely-cry/all9e v>ieties1 & ^? ) ! be/ develop$ b&$ /ructure1 occur 9 ! l>ge/ bodies ( rock1 :]e ! cool+ & consolidation w\ld be mo/ prolong$4#cef ,footnote #cef3 ,on ?is subject1 see ! pap]s by ,pr(essor ,judd already cit$4 #c4 ,! rem>kable diff]5ces 9 composition betwe5 ! d>k & pale lay]s 9 ! b&$ gabbros _c be acc\nt$ = by segregation or successive intrusion1 b seem to po9t to ! exi/5ce ( a het]og5e\s magma f :i* ^! di/9ct v>ieties ( mat]ial 7 simultane\sly intrud$4 #d4 ,f ! preval5ce ( a b$d$ /ructure & ! occurr5ce ( b&s & m irregul> portions ( consid]ably diff]5t texture & ev5 m9]alogical composition :i* int]sect ea* o!r1 x may be confid5tly inf]r$ t ev5 :at appe>s n[ z "o cont9u\s mass 0 produc$ by m ?an "o intrusion4 #e4 ,9 e case !re w\ld necess>ily be "o or m pipes up :i* ! igne\s mat]ial rose4 ,^! *annels might sometimes be wid] p>ts ( fissures1 su* z ^? fill$ by ! dykes4 ,9 o!r places1 !y may h be5 det]m9$ by old] v5ts1 :i* _h s]v$ = ! emission ( ! plateau-basalts & _! pyrocla/ic accompanim5ts4 ,!re c be no d\bt t "s ( ^! v5ts af=d$ egress = ! subsequ5t eruption ( granitoid rocks1 z w be po9t$ out 9 ! foll[+ *apt]s4 ,9 ! case ( ! gabbros1 h[ev]1 ! position ( ! v5ts seems to h be5 g5]ally conceal$ by ! t5d5cy ( ^! rocks to spread out lat]ally4 ,d5udation has cut deeply into ! gabbro-masses1 b app>5tly n deep en\gh to isolate any ( ! pipes f ! l>g] bodies ( mat]ial :i* issu$ f !m1 & ?us to leave solit>y necks l ^? 9 & ar\nd ! basalt-plateaux4 ,9 ,skye1 :]e ! c5tral core ( gabbro is l>ge/ & mo/ completely encircl$1 we _c tell h[ mu* ( x lies above ! true pipe or pipes1 & has spread out on all sides f ! c5tre ( eruption4 ,! preval5ce ( rude b$d+ & a b&$ /ructure indicate t mo/ ( ! visible rock occurs 9 ! =m ( sills1 successively inject$ n only into ! plateau-basalts1 b betwe5 & across ea* o!r4 ,r\nd ! m>g9 ( ! gabbro we und\bt$ly rea* horizons bel[ t rock1 & see t x lies z a cake or s]ies ( cakes ^u ! plateau-basalts4 ,! actual pipe or fissure ( supply mu/ 9 ea* case lie fur!r inw>d1 away f ! m>g91 & may be ( comp>atively small diamet]4 #f4 ,f ! c5tral pipe or gr\p ( pipes or fissures :i* rose f ! plat=m ( old] rocks into ! ?ick mass ( ! basalt-plateaux1 successive %eets ( dol]ite & gabbro 7 =c$ outw>d betwe5 ! lay]s ( basalt4 ,?is took place all r\nd ! orifices ( supply1 on _m diff]5t horizons1 & d\btless at _m diff]5t times4 ,9 "s cases1 ! intrusive %eets 7 inject$ into ! v bottom ( ! basalts1 & ev5 betwe5 ^! rocks & ! old] surface on :i* !y re/$4 ,?is is p>ticul>ly ! case 9 ,rum1 :]e ! gabbro-cones spr+ almo/ directly f ! anci5t grits1 s*i/s & s&/ones on :i* !y re/4 ,! intrusive %eets h likewise f\nd egress at e high] plat=m 9 ! basalt-s]ies1 up at lea/ to ! base ( ! pale gr\p 9 ,mull--t is1 ?r\gh a cont9u\s pile ( m ?an #bjjj feet ( b$d$ basalt4 ,b ! intrusion did n proce$ equally all r\nd an orifice4 ,at all ev5ts1 ! progress ( d5udation has reveal$ t on "o side ( a gabbro area ! inject$ portions may occur on a l[] /ratigraphical level ?an !y d on ! opposite side4 ,at ! ,cuill9 ,hills1 = example1 ! visible %eets ( dol]ite & gabbro to ! nor? ( ,coire na ,crei*e beg9 ab\t #afjj feet above ! sea1 :i* mu/ be mu* m ?an t di/ance above ! bottom ( ! basalts4 ,on ! s\?-ea/ side1 h[ev]1 !y come d[n to ne> ! base ( ! basalts at ,lo* ,scavaig2 t is to say1 _! l[e/ memb]s lie at lea/ #afjj feet bel[ ^? on ! opposite m>g94 #g4 ,! uprise ( s mu* igne\s mat]ial 9 "o or m funnels1 & its injection betwe5 ! b$s ( plateau-basalt1 w\ld necess>ily elevate ! surface ( ! gr\nd imm$iately above1 ev5 if we believe t surface to h be5 ev5tually disrupt$ & sup]ficial dis*>ges to h be5 e/abli%$4 ,if no disruption took place1 !n ! gr\nd w\ld probably be uprais$ into a smoo? dome1 ! old] lavas be+ b5t up ov] ! cone ( inject$ gabbro until ! portion ( ! plateau s pu%$ upw>d _h ris5 "s hundr$s ( feet above ! surr\nd+ c\ntry4 ,! am\nt ( elevation1 :i* w\ld ( c\rse be greate/ at ! c5tre ( ! dome1 might be f> f equable all r\nd1 "o side be+ pu%$ up fur!r or ) a /eep] slope ?an ano!r side4 ,b ev5 9 ! case ( ! ,cuill9 ,hill area1 x is conceivable t ! total uplift produc$ at ! surface a g5tle incl9ation ( no m ?an #h or #aj4 ,x is along ! p]iph]y ( a gabbro area t we may mo/ hopefully se>* = traces ( ?is uplift4 ,b un=tunately x is j !re t ! "w ( d5udation has be5 mo/ de/ructive4 ,!re appe>s also to h be5 a g5]al t5d5cy to sagg+ subsequ5t to ! gabbro protrusions1 & ! inw>d dip !reby produc$ has probably be5 in/rum5tal 9 effac+ at lea/ ! m g5tle outw>d incl9ations caus$ by ! uprise ( ! eruptive rock4 ,9 "o /rik+ locality1 h[ev]1 to :i* ,i h already ref]r$1 ! effects ( bo? movem5ts are1 ,i ?9k1 pres]v$4 ,! basalt-plateau ( ,/ra?aird1 :i* 9 its s\!rn portion exhibits ! ord9>y ne>ly level b$d+1 dips 9 its nor!rn "p at an unusually /eep angle to ! nor?-we/1 t[>ds ! gabbro mass ( ,bla? ,bhe9n4 ,b be=e rea*+ t m\nta9 ! basalts1 mu* int]b&$ ) %eets ( dol]ite & gabbro1 sudd5ly b5d up to =m ! prom95t em95ce ( ,an ,/ac1 :]e !y dip rapidly t[>ds s\?-ea/ & s\? 7,fig4 #ccd74 ,?is /eep dip away f ! c5tral mass ( gabbro1 is repeat$ 9 ! hills to ! nor?1 :]e ! b$s are incl9$ to nor?-ea/1 ! angle gradually less5+ nor?w>ds till !y are truncat$ by ! granophyre ( ,/ra?more4 ,! mass ( ,bla? ,bhe9n ?us occupies ! c5tre ( ! dome or anticl9e4 ,! !oretical /ructure ( "o ( ! gabbro bosses is repres5t$ 9 ,fig4 #cdc4 ,x w be und]/ood1 h[ev]1 t :at = ! sake ( cle>ness is "h repres5t$ 9 "o uni=m t9t ( black 9 reality consi/s ( an exce$+ly complex network ( %eets & dykes diff]+ f ea* o!r 9 texture & /ructure1 z well z 9 ! relative dates ( _! intrusion4 #h4 ,! injection ( s mu* igne\s mat]ial among ! b$d$ basalts has induc$ 9 ^! rocks a c]ta9 am\nt ( contact metamorphism4 ,i h ref]r$ to x z %[+ itself 9 ! field z a m>k$ induration1 ! rocks becom+ clos] gra9$1 dull1 spl9t]y1 & wea!r+1 ) a grey or :ite cru/1 :ile _! amygdales lose _! def9ite outl9es1 & epidote & calcite run 9 /r+s1 ve9s & pat*es ?r\gh _m p>ts ( ! rocks4 ,z already rem>k$1 x is difficult to det]m9e h[ mu* ( ?is *ange %\ld be ref]r$ to ! influ5ce ( ! gabbro1 & h[ mu* to t ( ! num]\s intrusions ( granophyre :i* may be apophyses ( mu* l>g] bodies ( t rock ly+ n f> und]nea?4 ,on acc\nt ( ?is difficulty1 ! m detail$ description ( ! metamorphism ( ! plateau-basalts is res]v$ = ,*apt] xlvi41 :]e x w f9d a place 9 connection ) ! effects produc$ by ! intrud$ granophyres1 :i* h und\bt$ly be5 m ext5sive ?an ^? effect$ by ! gabbros4 ,illu/ration3 ,fig4 #cdc4--,!oretical repres5tation ( ! /ructure ( "o ( ! ,gabbro ,bosses ( ! ,inn] ,hebrides4 a a1 plat=m ( old] rock on :i* ! b$d$ basalts 7b b7 h be5 p\r$ out2 c1 gabbro4 ,! /ructure & hi/ory ( ! gabbro bosses ( ! ,inn] ,hebrides f9d a close p>allel 9 ^? ( ! ,h5ry ,m\nta9s ( ,s\!rn ,utah1 s well describ$ by ,mr4 ,g4 ,k4 ,gilb]t ( ! ,unit$ ,/ates ,geological ,survey4#ceg ,9 t f9e gr\p ( m\nta9s1 ris+ to an extreme height ( #ejjj feet above ! surr\nd+ plateau1 & #aa1jjj feet above ! level ( ! sea1 masses ( tra*yte h be5 inject$ betwe5 s$im5t>y /rata belong+ to ! ,jura-,triassic & ,cretace\s sy/ems4 ,^! masses1 ?irty-six 9 numb]1 h consolidat$ 9 dome-%ap$ bodies1 t]m$ by ,mr4 ,gilb]t laccolites1 :i* h ar*$ up ! ov]ly+ /rata1 s5d+ %eets1 ve9s & dykes into !m1 & produc+ 9 !m ! ph5om5a ( contact metamorphism4 ,!re is no pro( t any ( ^! protrusions communicat$ ) ! surface1 & !re is positive evid5ce t mo/ if n all ( !m did n4 ,! progress ( d5udation has laid b>e ! inn] /ructure ( ?is rem>kable type ( hill1 & yet has left records ( e /age 9 its sculpture4 ,9 "o place are se5 only ar*+ /rata1 ! process ( erosion n hav+ yet cut d[n ?r\gh ! dome ( /ratifi$ rocks into ! tra*yte t 0 ! cause ( _! uprise4 ,9 ano!r place1 a few dykes pi]ce ! ar*2 9 a ?ird1 :]e a great] dep? has be5 b>$ away1 a network ( dykes & %eets is reveal$2 9 a f\r?1 ! surface ( ! und]ly+ laccolite is expos$2 9 a fif?1 ! laccolite1 long uncov]$1 has be5 c>v$ into picturesque cont\rs by ! wea!r1 & its orig9al =m is m or less de/roy$4#ceh ,footnote #ceg3 ,see ! rem>ks & diagram1 ante1 p4 #hf4 ,footnote #ceh3 ,geology ( ! ,h5ry ,m\nta9s1 by ,mr4 ,g4 ,k4 ,gilb]t1 ,u4,s4 ,geographical & ,geological ,survey ( ! ,rocky ,m\nta9 ,region1 #ahgg4 ,! gabbro laccolites ( ! ,we/ ( ,scotl& belong to an old] geological p]iod ?an ^? ( ,utah1 & h1 !re=e1 be5 long] subject to ! processes ( d5udation4 ,!y h be5 enorm\sly erod$4 ,! ov]ly+ cov] ( basalt has be5 /ripp$ (f f !m1 ?\gh f ! esc>pm5ts beyond !m x is n difficult 9 imag9ation to re/ore x4 ,9 ,rum x has be5 s completely remov$1 t only a few fragm5ts rema9 at "s di/ance f ! core ( gabbro1 :i* n[ /&s isolat$4 ,9 ,ardnamur*an1 & /ill m 9 ,skye1 ! surr\nd+ plateau ( basalt rema9s 9 contact ) ! gabbro bosses4 ,b 9 ,mull1 :]e ! plateau-basalts rea* n[1 & p]haps atta9$ orig9ally a great] ?ickness ?an any:]e else1 !y h protect$ ! intrusive %eets1 :i* are !re=e less deeply cut away ?an 9 any ( ! o!r di/ricts1 & no great c5tral core ( gabbro has yet be5 uncov]$4 ,,*apt] ,,xlv ,,! ,,acid ,,rocks ,_! ,petrography--,_! ,/ratigraphical ,position & its ,analogies 9 ,c5tral ,france ,we n[ come to ! exam9ation ( ano!r di/9ct phase ( volcanic action dur+ ,t]ti>y "t 9 ,brita94 ,! igne\s rocks t h be5 "u consid]ation 9 ! =ego+ *apt]s1 :e!r p\r$ out at ! surface or inject$ bel[ gr\nd1 h be5 *iefly ( basic1 p>tly inde$1 l ! p]idotites1 ( ultra-basic "*4 ,"s1 h[ev]1 h %[n an &esitic or int]m$iate composition4 ,ref]5ce has also be5 made to ! probable eruption ( acid rhyolites 9 ! long int]val betwe5 ! outfl[ ( ! l[] & ! upp] basalts 9 ,antrim4 ,b we n[ enc\nt] a great s]ies1 decid$ly acid 9 composition1 9 ! m l>gely cry/all9e memb]s ( :i* ! excess ( silica is visible to ! eye 9 ! =m ( free qu>tz4 ,:ile !re is a /rong contra/ 9 *emical composition betwe5 ?is s]ies & ! rocks hi!rto "u discussion1 !re are also m>k$ diff]5ces 9 /ructure & mode ( occurr5ce4 ,l ! gabbros1 all ! masses ( acid rock n[ visible appe> to be intrusive4 ,!y h be5 inject$ b5ea? ! surface1 & !re=e record = u subt]ranean r ?an sup]ficial manife/ations ( volcanic action4 ,! exi/5ce ( rocks ( ?is class 9 ! mid/ ( ! basic masses has long be5 recogniz$4 ,!y 7 notic$ by ,jameson1 :o describ$ ! hills betwe5 ,lo* ,sliga*an & ,broad=d z compos$ ( a comp\nd ( felsp> & qu>tz1 or :at may be call$ a granitel1 ) occasional ve9s ( pit*/one4#cei ,maccullo* gave a full] acc\nt ( ! same region1 & class$ ! rocks z *iefly sy5ite & porphyry4#cfj ,9 ,antrim1 also1 ev5 9 ! mid/ ( ! basalt-tablel&1 masses ( pit*/one-porphyry pe>l/one-porphyry1 clay-porphyry1 & grey/one 7 obs]v$ & describ$4#cfa ,9 m rec5t ye>s ,pr(essor ,zirkel has giv5 a brief acc\nt ( ! s-call$ sy5ite & porphyry ( ,mull & ,skye1#cfb & ! late ,pr(essor ,von ,lasaulx fully describ$ ! tra*yte or rhyolite ( ,antrim4#cfc ,footnote #cei3 ,m9]alogical ,travels1 ii4 #ij4 ,footnote #cfj3 ,we/]n ,isles1 see ! descriptions ( ,skye1 ,mull & ,rum4 ,footnote #cfa3 ,b]g]1 ,trans4 ,geol ,soc4 iii4 7#ahaf71 p4 #aij2 ,portlock1 ,j\rn4 ,geol4 ,soc4 ,irel&1 vol4 i4 7#ahcd71 p4 #i4 ,footnote #cfb3 ,zeits*4 ,deuts*4 ,geol4 ,gesells*4 xxiii4 7#ahga71 pp4 #ed1 #gg1 #hd1 #hh4 ,footnote #cfc3 ,ts*]mak's ,m94 und ,petrog4 ,mit!ilung51 #ahgh1 p4 #dab4 ,! *emical composition ( ?is rock & its place among ! rhyolites _h already be5 det]m9$ by ,e4 ,t4 ,h>dman f analysis1 ,j\rn4 ,geol4 ,soc4 ,irel&1 vol4 iii4 7#ahga71 p4 #cb4 ,?is int]e/+ s]ies ( rocks embraces a great] v>iety ( petrographical *>act]s ?an any o!r portion ( ! ,briti% ,t]ti>y volcanic rocks4 ,on ! "o h&1 x pres5ts ?or\ghly vitre\s masses1 "s ( :i* 9 _! col\r1 lu/re & microscopic /ructure rem9d u ( rec5t obsidians4 ,on ! o!r h&1 x af=ds co>sely cry/all9e comp\nds1 to :i* no o!r "n ?an granite c be assign$1 & :i*1 did we n "k _! geological position1 might almo/ be class$ ) "s ( ! mo/ anci5t eruptive rocks4 ,betwe5 ^! two extremes abundant gradations may be f\nd1 includ+ beautiful sph]ulitic rocks1 felsites & rhyolites4 ,9 deal+ ) su* a s]ies ( intrusive rocks1 we aga9 enc\nt] ! difficulty ( rea*+ c]ta9ty z to _! relative dates ( eruption1 s9ce 9 ea* case all t c usually be affirm$ is t ! intrusive mass is y\ng] ?an t into :i* x is inject$4 ,x is q possible t protrusions ( acid rocks occurr$ at int]vals dur+ ! accumulation ( ! basic masses1 z may p]haps be inf]r$ f ! rhyolite-tuffs & conglom]ates ( ,antrim & f ! occurr5ce ( fragm5ts ( silice\s lavas 9 ! gravels ne> ! base ( ! basalt-plateau ( ,mull1 & 9 ! agglom]ates ( t isl& z well z ( o!r di/ricts4#cfd ,x is probable1 !re=e1 t at ! "t :5 ! basalts ( ! plateaux 7 emitt$1 !re exi/$1 )9 rea* ( volcanic explosions1 masses ( granophyric1 felsitic or rhyolitic rocks1 fragm5ts f :i* 7 %ot up ! funnels ( dis*>ge4 ,t portions ( ^! rocks 7 actually intrud$ into ! basalt-%eets be=e ! build+ up ( ! plateaux 0 complet$ appe>s to be prov$ 9 ,antrim4 ,else:]e1 h[ev]1 no evid5ce has yet be5 obta9$ ( any su* intrusion until aft] ! close ( ! plateau-p]iod4 ,on ! contr>y1 9 e case :]e ! relative ages ( ! rocks c be fix$1 ! acid are y\ng] ?an ! basic protrusions4 ,footnote #cfd3 ,ref]5ce may also aga9 be made to ! agglom]ates ( ,/ra?1 ,skye1 :i* conta9 9 "s p>ts abundant fragm5ts ( acid rocks t closely resemble "s ( ! masses ( granophyre :i* disrupt ^! agglom]ates4 ,! only kn[n exceptions to ?is rule are ! late/ basalt-dykes4 ,h5ce1 :ile amid ! l>ge & v>i$ s]ies ( acid rocks1 :i* no d\bt repres5ts a wide int]val ( "t1 "s may belong to comp>atively e>ly epo*s 9 ! protract$ volcanic p]iod1 ! actual available evid5ce places ! emission ( ^! rocks1 z a :ole1 t[>ds ! end ( ! volcanic hi/ory4 ,?is evid5ce ,i %all br+1 =w>d 9 full detail1 s9ce x necessitates an ab&onm5t ( :at has be5 ! g5]al belief 9 reg>d to ! relative ages ( ! rocks4 i4 ,,petrography ,,( ,,! ,,acid ,,rocks ,! classification ( ! rocks :i* be/ h>monizes ! field-evid5ce & ! detail$ /udy ( _! m9]alogical composition1 is "o t arranges ^! volcanic protrusions into two s]ies4 ,9 ! "o1 ! or?oclase is sanid9e1 & ! rocks range f ! mo/ vitre\s pit*/one ?r\gh p]litic & sph]ulitic v>ieties to rhyolite 7qu>tz-tra*yte74 ,9 ! o!r s]ies1 :i* embraces by f> ! l>ge/ proportion ( ! :ole1 ! or?oclase is always turbid1 & 9 ?is respect z well z 9 _m o!rs ! rocks rem9d u r ( anci5t eruptive masses ?an ( ^? :i* h appe>$ 9 ,t]ti>y "t4 ,!y range f fl9ty felsitic v>ieties1 :i* are obvi\sly devitrifi$ glasses1 ?r\gh diff]5t textures ( qu>tz-porphyry into granophyre1 & f9ally into granite4 ,z ,i h be5 unable to recognize any ess5tial diff]5ce ( /ructure & composition betwe5 ^! acid ,t]ti>y rocks & ^? ( f> e>li] geological "t1 ,i give !m ! names :i* no petrograph] w\ld hesitate to apply to !m if !y 7 ( ,palozoic age4 ,x has long appe>$ to me t ^! rocks furni% conclusive evid5ce ( ! mislead+ artificiality ( any petrographical nom5clature 9 :i* relative antiquity is made an ess5tial elem5t ( discrim9ation4 ,granite4--,t true granites =m "p ( ! ,t]ti>y volcanic s]ies ( ! ,briti% ,isles has n[ be5 completely e/abli%$4 ,!y occur z bosses & sills :i* h be5 intrud$ into ! gabbros & all old] rocks4 ,!y are ?us prov$ n only to belong to ! ,t]ti>y p]iod1 b to "o ( ! late/ phases ( its volcanic hi/ory4 ,b besides ^! granites1 ! relative age ( :i* c be def9itely fix$1 !re occur o!rs :i*1 /&+ alone & at "s di/ance f ! basaltic plateaux1 c only be inf]5tially class$ 9 ! ,t]ti>y s]ies4 ,to ?is gr\p belong ! granite masses ( ! ,isle ( ,arran & ! ,m\rne ,m\nta9s 9 nor?-ea/]n ,irel&4 ,tak+ fir/ ! unque/ionably ,t]ti>y granites :i* occur z bosses & intrusive %eets1 we h to note t ! m co>sely cry/all9e granophyres are h>dly to be di/+ui%$ ext]nally f granite4 ,z ! d>k f]ro-magnesian con/itu5t ( ^! rocks 0 g5]ally believ$ to be hornbl5de1 !y 7 call$ by ! old] petrograph]s sy5ite2 t is1 granite ) hornbl5de in/ead ( mica4 ,! peculi> micropegmatitic gr\ndmass1 :i* con/itutes ! di/+ui%+ feature ( ! granophyres1 may occasionally be obs]v$ s r$uc$ 9 am\nt z only to appe> "h & !re betwe5 ! o!r m9]als1 :i* are gr\p$ 9 a granitic /ructure4 ,f ?is condition1 "o /ep fur!r c>ries u into a true granite1 f :i* all trace ( ! granophyric "* has disappe>$4 ,su* gradations may be trac$ ev5 )9 %ort di/ances 9 ! same boss ( rock4 ,?us1 9 ! hornbl5de-biotite-granite boss ( ,be9n-an-,dubhai*1 ,skye1 a ?or\ghly granitic arrangem5t ( ! compon5t m9]als is obs]vable 9 ! c5tre1 :ile a specim5 tak5 f ne> ! edge on ! %ore ( ,camas ,malag %[s ! developm5t ( a granophyric gr\ndmass4 ,b1 ?\gh ! l>ge bosses are usually some:at co>sely cry/all9e 9 ! c5tre1 & t5d to assume f9] felsitic textures ar\nd _! bord]s1 z 0 obs]v$ long ago by ,oeynhaus5 & ,von ,de*51#cfe ! granitic /ructure is sometimes exhibit$ ev5 at ! v edge1 & n only s1 b 9 ! dykes t protrude f ! bosses into ! surr\nd+ rocks4 ,?us ! ,be9n-an-,dubhai* mass1 at its m>g9 9 ,camas ,malag1 s5ds a ve9 into ! surr\nd+ lime/one1 b ?\gh m close-gra9$ ?an ! ma9 body ( ! rock1 ?is ve9 is nei!r felsitic nor granophyric1 b truly granitic 9 /ructure4 ,footnote #cfe3 ,k>/5's ,ar*iv1 i4 p4 #hi4 ,s f> z ,i h obs]v$1 ! true granites conta9 a br[n mica & also a little hornbl5de1 bo? visible to ! nak$ eye1 b g5]ally some:at decompos$4 ,^! rocks are ?us hornbl5de-biotite-granites 7amphibole-granitites ( ,ros5bus*74 ,!y may be def9$ z m$ium-gra9$ aggregates ( qu>tz1 or?oclase 7also plagioclase71 biotite & hornbl5de1 ) sometimes magnetite1 apatite1 epidote & zircon4 ,dr4 ,hat* f\nd t 9 "s in/ances 7,be9n-an-,dubhai*7 ! qu>tz conta9s m9ute inclusions 7glass871 be>+ immovable bubbles ) /rongly-m>k$ cont\rs2 :ile 9 o!rs 7,be9n-na-,*ro1 ,skye7 ?is m9]al is full ( liquid inclusions ) bubbles1 sometimes vibratile1 sometimes fix$4 ,he rem>k$ t ! qu>tz & felsp> h consolidat$ almo/ simultane\sly1 b t 9 "s in/ances 7,m>sco1 ,gl5 ,sliga*an7 !re are isolat$ r\ghly idiomorphic cry/als1 ( a :ite1 less turbid or?oclase1 :i* belong to a slightly e>li] consolidation ?an t ( ! m kaol9iz$ felsp> ( ! re/ ( ! rock4 ,! granite ( ! isl& ( ,arran1 9 ! ,bir? ( ,clyde1 :i* is "h includ$ 9 ! ,t]ti>y volcanic s]ies1 has long be5 recogniz$ z consi/+ ( two di/9ct portions1 an ea/]n or co>se-gra9$1 & a we/]n or f9e-gra9$ v>iety4 ,! latt] s5ds ve9s into ! =m]4 ,^! granites conta9 or?oclase1 plagioclase1 qu>tz & d>k mica1 ! qu>tz be+ (t5 idiomorphic ) respect to ! felsp>1 & a t5d5cy t[>ds a micropegmatitic /ructure be+ sometimes obs]vable4 ,a di/+ui%+ *>act]i/ic ( ! ,arran granite is ! cav]n\s or drusy /ructure :i* x pres5ts1 ! cavities be+ (t5 l9$ ) well-cry/alliz$ or?oclase & smoky qu>tz4#cff ,! granite ( ! ,m\rne ,m\nta9s 9 ,irel& closely resembles t ( ,arran4 ,its druses1 ) _! beautifully t]m9at$ m9]als1 h long be5 well kn[n4 ,footnote #cff3 ,see ,mr4 ,teall's ,briti% ,petrography1 p4 #cbh4 ,microgranite4--,?is t]m is appli$ to c]ta9 intrusive masses1 :i* megascopically may be class$ ) ! qu>tz-porphyries & felsites1 b :i* microscopically are f\nd to possess a holocry/all9e granitic gr\ndmass ( qu>tz & or?oclase1 ?r\gh :i* are scatt]$ porphyritic cry/als ( ! same two m9]als1 sometimes also ) plagioclase1 augite1 magnetite or apatite4 ,rocks ( ?is type d n appe> to be abundant4 ,!y occur z dykes & bosses1 b occasionally also z %eets4 ,i h collect$ !m f ,skye1 ,rum & ,ardnamur*an4 ,granophyre4--,"u ?is "n may be gr\p$ ! l>ge majority ( ! acid rocks :i* play an important "p 9 ! geology ( ! ,we/ ( ,scotl&4 ,!y are typically develop$ 9 ! isl&s ( ,mull & ,skye4 ,g5]ally pale grey or buff 9 col\r1 !y range 9 texture f ! true granites1 into :i*1 z above /at$1 !y graduate1 to exce$+ly close-gra9$ v>ieties l ! felsites ( ,palozoic =mations4 ,9 ! great majority ( !m ! micrographic int]gr[? ( qu>tz & felsp>1 kn[n z micropegmatite1 is _! conspicu\s /ructure1 & ev5 con/itutes mo/ ( _! sub/ance4 ,!y may ?us be class$ g5]ally z granophyres1 9 ! s5se 9 :i* ?is t]m is employ$ by ,ros5bus*1 b )\t 8 limitation ( x to pre-,t]ti>y rocks4 ,! specific gravity ( ^! rocks has be5 det]m9$ f a s]ies ( specim5s by ,mr4 ,a4 ,h>k] to range f ab\t #bc among ! felsites to #bg among ! granites4 ,no *emical analyses ( ^! rocks h yet be5 made1 b !y h be5 subject$ to microscopical exam9ation1 & _! g5]al /ructure & composition are n[ kn[n4 ,! typical granophyre ( ! ,inn] ,hebrides outw>dly closely resembles an ord9>y granite ( m$ium gra91 9 :i* ! compon5t dull felsp> & cle> qu>tz c be readily di/+ui%$ by ! nak$ eye4 ,?r\gh\t all ! v>ieties ( texture !re is a /rong t5d5cy to ! developm5t ( m9ute irregul>ly-%ap$ drusy 7mi>olitic7 cavities1 :i* "h & !re give a c>i\s aspect to ! rock4 ,t ^! cavities1 h[ev]1 are "p ( ! orig9al /ructure ( ! rock1 & are n due to m]e wea!r+1 is %[n by ! well-t]m9at$ cry/als ( qu>tz & felsp> :i* project into !m4 ,on a small scale1 x is ! same /ructure s *>act]i/ic ( ! granite ( ! ,m\rne ,m\nta9s & ( p>ts ( t ( ,arran4 ,exam9$ "u ! microscope1 a normal specim5 ( ! granophyre ( ! ,we/]n ,isles pres5ts a holocry/all9e gr\ndmass1 :i* fills all ! int]spaces betwe5 ! cry/als ( e>li] consolidation4 ,?is gr\ndmass consi/s ( an aggregate ( cle> qu>tz & turbid or?oclase1 arrang$ z micropegmatite1 b also 9 m or less idiomorphic cry/als4 ,9 "s p>ts1 ! two dom9ant m9]als are gr\p$ 9 alt]nate p>allel fibres1 div]g+ f ! surface ( ! enclos$ cry/als1 :i* are ?us m or less completely surr\nd$ by a radially fibr\s mass4 ,! felspa?ic portion ( ! micropegmatite :i* usually surr\nds ! or?oclase cry/als1 :5 view$ betwe5 cross$ ,nicols1 is f\nd to ext+ui% simultane\sly ) ! c5tral cry/al4#cfg ,9 o!r p>ts1 ! felsp> =ms a k9d ( network1 ! me%es ( :i* are fill$ up ) qu>tz4 ,?r\gh ! gr\ndmass1 besides ! cle> qu>tz & dull or?oclase1 "s f]ro-magnesian or o!r additional con/itu5t is g5]ally di/ribut$1 b usually some:at decompos$4 ,9 c]ta9 v>ieties ,dr4 ,hat* f\nd an abundant br[n mica1 z 9 ! rock at ,camas ,malag1 ,skye4 ,9 o!rs1 a pyrox5e occurs1 :i* he obs]v$ 9 m9ute gre5i% gra9s1 sometimes completely enclos$ 9 ! qu>tz4 ,9 a ?ird v>iety1 ! d>k con/itu5t is hornbl5de1 ! mo/ rem>kable example ( :i* is "o to be se5 at ,i%riff1 9 ! ,gl5 ,m ( ,mull1 :]e ! f]ro-magnesian m9]al takes ! =m ( long dirty-gre5 ne$les1 conspicu\s on a wea!r$ surface ( ! rock4 ,a f\r? v>iety is di/+ui%$ by conta9+ plagioclase 9 addition to or in/ead ( or?oclase4 ,9 ! rock ( ! %eet =m+ ,cnoc ,c>na*1 ne> ,hea/1 9 ,skye1 ,dr4 ,hat* obs]v$ bo? or?oclase & plagioclase scatt]$ ?r\gh a f9e micropegmatitic gr\ndmass1 & 9 a "p ( ! boss at ,i%riff he f\nd ! rock to be compos$ ma9ly ( plagioclase1 9 a micropegmatitic gr\ndmass ( qu>tz & felsp>1 ) a few scatt]$ gra9s ( a pale br[n augite & gra9s ( magnetite4 ,a fif? v>iety is m>k$ by ! prom95ce ( ! cry/als ( qu>tz & felsp> ( e>li] consolidation1 & by ! f95ess ( gra9 9 ! surr\nd+ micropegmatitic gr\ndmass1 :]eby a di/9ct porphyritic /ructure is develop$4 ,rocks ( ?is k9d are megascopically l ord9>y qu>tz-porphyries4 ,/ill ano!r v>iety has be5 detect$ by ,mr4 ,teall 9 ! rock ( ,meall ,de>g1 at ! head ( ,gl5 ,sliga*an1 ,skye1 9 :i*1 besides irregul> pat*es :i* may repres5t decay$ biotite1 & o!rs :i* are possibly ilm5ite1 ! r>e m9]al riebeckite is pres5t4#cfh ,footnote #cfg3 ,mr4 ,teall1 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid7 p4 #bai4 ,see also 8 ,briti% ,petrography1 p4 #cbg4 ,footnote #cfh3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid71 p4 #bai4 ,felsite4--,! close-gra9$ rocks into :i* ! ord9>y granophyres frequ5tly graduate may be conv5i5tly gr\p$ "u ! g5]al "n ( ,felsite4 ,!y diff] 9 no ess5tial feature f ! felsites ( ! ,palozoic =mations4 ,!y are m p>ticul>ly develop$1 z might be expect$1 9 ^? places :]e ! conditions h be5 mo/ fav\rable = rapid cool+1 :ile ! m co>sely cry/all9e granophyres occur :]e ! mat]ial may be suppos$ to h consolidat$ mo/ sl[ly4 ,:]e ! acid magma has be5 inject$ into *9ks & fissures s z to take ! =m ( ve9s or dykes1 x is sometimes felsitic1 sometimes granophyric1 9 texture4 ,along ! m>g9 ( l>ge bosses1 l ^? ( ,mull & ,skye1 x frequ5tly ?\gh n inv>iably has assum$ a f9e texture1 ) ev5 sph]ulitic & fl[-/ructures4 ,b 9 ! c5tre ( l>ge bosses x usually appe>s z co>se granophyre or z granite4 ,! felsites v>y 9 texture f fl9ty or horny to dull f9ely-granul>1 & 9 col\r f :ite ?r\gh %ades ( grey1 buff & lilac1 to black1 g5]ally ) porphyritic felsp>s & blebs ( qu>tz4 ,:]e ^! porphyritic enclosures increase 9 size & numb]1 ! rocks _c be di/+ui%$ ext]nally f anci5t qu>tz-porphyries4 ,9 g5]al ! gr\ndmass ( ^! rocks has be5 completely devitrifi$4 ,b 9 "s dykes en\gh ( ! glassy base rema9s to %[ _! orig9al vitre\s condition4 ,a gradation c ?us be trac$ f ?or\ghly glassy pit*/one into completely li?oid felsites & cry/all9e granophyres4 ,a *>act]i/ic feature ( ! felsitic v>ieties ( acid rock is _! fl[-/ructure1 :i* !y (t5 display 9 great p]fection4 ,sometimes1 inde$1 ?is /ructure has be5 s /rongly develop$ z to cause ! rock to wea!r along ! planes ( fl[ & to break up into ?9 slabs4 ,_m ( ^! rocks also pres5t admirably develop$ sph]ulitic /ructures1 v>y+ f microscopic m9ut5ess up to l>ge r\nd or egg-%ap$ balls ne>ly two in*es 9 diamet]1 & (t5 di/ribut$ 9 l9es along ^? ( fl[-/ructure4 ,!y likewise exhibit a frequ5t developm5t ( micropegmatite4 ,no l9e inde$ c be drawn betwe5 ^! felsites & ! granitoid v>ieties1 = ! same *>act]i/ic granophyric int]gr[? ( felsp> & qu>tz runs ?r\gh !m all4 ,pit*/one4--,?is "n is appli$ to ! glassy v>ieties ap>t f _! *emical composition1 & specially d5otes ! possession ( a vitre\s /ructure4 ,"s ( ! rocks to :i* x has be5 appli$ are probably glassy v>ieties ( &esite1 o!rs are dacites1 :ile "s may be z acid z ! mo/ acid felsites & granophyres4 ,! pit*/ones are f\nd 9 ve9s or dykes :i* trav]se diff]5t geological =mations up to & includ+ ! great granophyre bosses ( ! ,inn] ,hebrides4 ,!y v>y 9 col\r f a deep jet-black or rav5-black to a pale bottle-gre51 & 9 lu/re f an almo/ glassy obsidian-l to a dull res9\s aspect4 ,occasionally !y assume a felsitic texture1 ow+ to devitrification1 & also a f9ely sph]ulitic /ructure4 ,"s v>ieties appe> to ! nak$ eye to be p]fectly homog5e\s1 o!rs become porphyritic by ! appe>ance ( abundant sanid9e cry/als4 ,! microscopic /ructure ( ! ,briti% pit*/ones has n yet be5 fully work$ out4 ,! beautiful fea!ry microlites ( ! ,arran dykes1 fir/ made kn[n by ,david ,=bes1 & subsequ5tly describ$ by ,zirkel1 ,allport & o!rs1 are well kn[n objects to geological collectors4 ,dr4 ,hat*1 9 ^: h&s ,i plac$ my tol]ably l>ge collection ( specim5s & _! ?9 slides1 furni%$ me ) "s prelim9>y notes on ! slides1 f :i* ! foll[+ g5]aliz$ summ>y is compil$4 ,at ! "o end ( ! pit*/one gr\p we h a ne>ly pure glass1 ) no microlites1 & only a few scatt]$ cry/als ( sanid9e1 qu>tz1 augite or magetite4 ,! glass 9 ?9 slices is almo/ col\rless1 b g5]ally incl9es to yell[1 sometimes to d>k-grey4 ,"s v>ieties ( ! rock are cr[d$ ) microlites1 9 o!rs ^! bodies are ga!r$ into gr\ps1 ! glass betwe5 :i* is ne>ly free f !m4 ,among ! m9]als t h be5 obs]v$ 9 ?is microlitic =m are sanid9e1 augite1 hornbl5de 7=m+ ! beautiful gre5 fea!ry or f]n-l aggregates 9 ! ,arran pit*/ones1 ,fig4 #c7 & magnetite4 ,sometimes ! rudim5t>y =ms appe> z globulites1 or z belonites1 b m commonly z d>k tri*ites4 ,among ! m def9ite m9]al =ms are gra9s ( sanid9e1 qu>tz & augite4 ,! porphyritic cry/als are *iefly sanid9e1 augite & magnetite1 b plagioclase occasionally occurs4 ,! developm5t ( sph]ulites is well se5 9 a few ( ! slides1 & occasionally p]litic /ructure makes its appe>ance4 ,! int]e/+ rhyolitic areas ( ,antrim include sev]al v>ieties ( pit*/one4 ,"o ( ^! is describ$ by ,pr(essor ,cole z a glassy pyrox5e-rhyolite1 on ! v]ge ( ! rhyolitic &esites4 ,ano!r is a blue-black porphyritic obsidian4#cfi ,footnote #cfi3 ,sci5tif4 ,trans4 ,roy4 ,dubl9 ,soc4 vol4 vi4 7s]4 ii47 #ahif1 p4 #gg4 ,rhyolite 7,qu>tz-,tra*yte74--,?is rock has be5 abundantly erupt$ 9 nor?-ea/ ,irel&1 :]e x rises 9 occasional bosses among ! plateau-basalts4#cgj ,x is be/ expos$ at ! ,t>dree & ,c>ne>ny ,hills1 :]e x has long be5 qu>ri$4 ,its petrographical *>act]s at t locality 7 describ$ by ,von ,lasaulx z ^? ( a typical qu>tz-tra*yte ri* 9 tridymite1 & conta9+ l>ge cry/als ( glassy sanid9e1 isolat$ n>r[ la?s ( plagioclase 7probably &es9e71 gra9s ( smoky-grey qu>tz1 p>tly b\nd$ by dihexah$ral faces1 & a few scatt]$ flakes ( a d>k-col\r$ mica4 ,! gr\ndmass is microgranitic1 & "u a high p[] is resolvable into a confus$ aggregate ( m9ute microlites ( felsp>1 ) int]/itial qu>tz-granules4#cga ,m rec5tly a detail$ inve/igation ( ! petrography ( ! ,antrim rhyolites has be5 conduct$ by ,pr(essor ,cole1 :o has call$ att5tion to _! rem>kable v>ieties ( /ructure1 rang+ f p]fect volcanic glass to a ?or\ghly li?oidal texture1 & exhibit+ fl[1 p]litic & sph]ulitic /ructures4#cgb ,footnote #cgj3 ,fragm5ts ( acid rock 7 detect$ by ,pr(4 ,cole 9 ! gravel among ! ,ardtun basalt ( ,mull1 z already notic$ on p4 #bab4 ,footnote #cga3 ,ts*]mak's ,m94 und ,pet4 ,mit!il4 #ahgh1 p4 #dab4 ,footnote #cgb3 ,sci5tif4 ,trans4 ,roy4 ,dubl9 ,soc4 vol4 vi4 7s]4 ii47 #ahif1 p4 #gg4 ,?is pap] gives an excell5t acc\nt ( ! microscopical "* & m9]alogical & *emical compositions ( ^! rocks4 ,intrusive masses ( rhyolite are also f\nd 9 ! ,c>l+=d region4 ,"o ( ^!1 se5 at ,=khill1 is a velvet-black almo/ res9\s rock ) abundant qu>tz & felsp>1 & sometimes display+ beautiful fl[-/ructure4 ,x w be m p>ticul>ly describ$ 9 ,*apt] xlvii4 ,"s ( ! acid dykes & sills ( ! ,inn] ,hebrides are v>ieties ( rhyolite4 ,no und\bt$ example has yet be5 obs]v$ ( a sup]ficial rhyolite-lava1 ?\gh su* n improbably appe>$ 9 ! int]val betwe5 ! l[] & upp] basalts ( ,antrim4 ii4 ,,/ratigraphical ,,position4--,,analogies ,,f ,,c5tral ,,france ,9 ! hi/ory ( op9ion reg>d+ ! relative position ( ! ,t]ti>y eruptive rocks1 no feature is s rem>kable z ! univ]sal acceptance ( ! misconception reg>d+ ! place ( ! acid protrusions4 ,9 trac+ ?is mi/ake to its s\rce1 we f9d t x probably arose f ! fact t along _! l9e ( junction ! granitoid masses g5]ally und]lie ! basic4 ,?is ord] ( sup]position1 :i* w\ld usually suffice to fix ! age ( two gr\ps ( /ratifi$ rocks1 is obvi\sly n ( itself en\gh to settle ! relative epo*s ( two gr\ps ( intrusive rocks4 ,yet x has be5 assum$ z adequate = ?is purpose1 & h5ce :at c be prov$ to be really ! y\nge/ has be5 plac$ z ! olde/ "p ( ! ,t]ti>y volcanic s]ies4 ,maccullo*1 :o %[$ t 8 sy5ites & porphyries _h invad$ ! ,second>y /rata ( ! ,inn] ,hebrides1 & mu/ !re=e be ( y\ng] date ?an ^!1 left _! relations to ! o!r igne\s rocks ( ! region 9 a curi\sly indef9ite position4 ,he 0 dispos$ to reg>d !m all z m]ely p>ts ( "o great s]ies2 & seems to h ?\ght t !y graduate into ea* o!r1 & t any attempt to discrim9ate betwe5 !m z to relative age is sup]flu\s4 ,yet he evid5tly felt t ! contra/s ( topography :i* he describ$ c\ld h>dly fail to raise ! "q ( :e!r rocks s di/9ct 9 outw>d =m did n diff] also 9 relative antiquity4 ,b he dismiss$ ! "q )\t answ]+ x1 rem>k+ t if !re is any diff]5ce ( age betwe5 ! two k9ds ( rock1 !re appe>s no great prospect ( discov]+ x4#cgc ,he records an in/ance ( a ve9 ( sy5ite trav]s+ ! hyp]/h5e rock 9 ! valley ( ,coruisk4 ,if ?is ve91 he says1 c\ld be trac$ to ! mass ( sy5ite1 x might be held a suffici5t gr\nd ( judgm5t1 b "u ! pres5t circum/ances x is incapable ( af=d+ any assi/ance 9 solv+ ! difficulty4#cgd ,in/ead1 h[ev]1 ( be+ a solit>y in/ance1 x is only "o ( hundr$s ( simil> intrusions :i* c be connect$ ) ! g5]al body ( granitic & granophyric masses1 & :i* put ! relative ages ( ! sev]al gr\ps ( rock beyond any fur!r d\bt4 ,footnote #cgc3 ,we/]n ,isl&s1 i4 p4 #cfh2 see also pp4 #dhh1 #ege1 #egh4 ,footnote #cgd3 ,op4 cit4 p4 #cgj4 ,b\1 :o knew ! geology ( "s ( ! ext9ct volcanic regions ( ,europe1 recogniz$ ! simil>ity ( ! ,scotti% masses to ^? ( ! ,cont95t1 & class$ ! acid rocks z tra*ytes4 ,he saw 9 ea* ( ! volcanic areas ( ! ,we/ ( ,scotl& a tra*ytic c5tre1 & suppos$ t ! m granitoid p>ts might repres5t ! c5tres 9 ! ,european tra*ytic masses4 ,he trac$ 9 imag9ation ! fl[ ( ! lava-/reams f ^! foci ( volcanic activity1 di/+ui%+ !m z products ( diff]5t epo*s ( eruption1 among ! la/ ( :i* he ?\ght t ! tra*ytic porphyries might h be5 dis*>g$4 ,he admitt$1 h[ev]1 t 8 re/oration c\ld n be bas$ on ! few available data )\t rec\rse to !oretical notions drawn f ! analogy ( o!r regions4#cge ,footnote #cge3 ,essai ,gologique sur l'cosse1 pp4 #bia1 #cbb1 #cbg4 ,9 ! c>eful exploration ( ! c5tral region ( ,skye made by ,von ,oeynhaus5 & ,von ,de*51 ^! able obs]v]s trac$ ! b\nd>y betwe5 ! sy5ite & ! hyp]/h5e rock2 & z !y f\nd ! =m] ly+ und]nea? ! latt]1 !y seem naturally to h consid]$ x to be ! old] protrusion ( ! two4#cgf ,pr9cipal ,=bes came to a simil> conclusion f ! fact t he f\nd ! d>k gabbro always ov]ly+ ! light-col\r$ felspa?ic masses4#cgg ,pr(essor ,zirkel also obs]v$ ! same relative position1 & adopt$ ! same inf]5ce z to ! relative age ( ! rocks4#cgh ,pr(essor ,judd foll[$ ^! writ]s 9 plac+ ! acid rocks be=e ! basic4 ,he suppos$ ! granitoid masses to =m ! cores ( volcanic piles probably ( ,eoc5e age1 ?r\gh & ov] :i* ! protrusions ( gabbro & ! eruptions ( ! plateau-basalts took place4#cgi ,footnote #cgf3 ,k>/5's ,ar*iv1 i4 p4 #hb4 ,x w be %[n 9 lat] pages t ! app>5t infraposition ( ! granophyre is (t5 deceptive1 ! real junction be+ v]tical4 ,footnote #cgg3 ,ed94 ,new ,phil4 ,j\r4 xl4 7#ahdf7 p4 #hd4 ,footnote #cgh3 ,zeits*4 ,deuts*4 ,geol4 ,gesells*4 xxiii4 7#ahga7 pp4 #ij1 #ie4 ,he says t ! gabbro seems to be ! y\ng] rock1 s f> z _! relations to ea* o!r c be se54 ,footnote #cgi3 ,qu>t4 ,j\r4 ,geol4 ,soc4 xxx4 7#ahgd7 p4 #bee4 ,! evid5ce = ! po/]iority ( ! acid rocks w be fully detail$ 9 lat] pages4 ,be=e ent]+ ^u its consid]ation1 h[ev]1 ,i w\ld rem>k t ! uprise ( ! ,briti% granophyres pres5ts s _m po9ts ( resemblance to t ( ! tra*ytes & phonolites among ! basalt-plateaux ( ,auv]gne & ! ,velay 9 ,c5tral ,france1 t a brief acc\nt ( ! acid protrusions ( ^! regions may be suitably giv5 "h z an introduction to ! acc\nt ( ^? ( ! ,inn] ,hebrides4 ,a succession ( /ages 9 ! progress ( d5udation all[s u to foll[ ! gradual isolation & dissection ( ! ,fr5* volcanic gr\ps4 ,! y\nge/ examples occur 9 ! *a9 ( cones & crat]s1 9 ! region ( ! ,puy de ,dme4 ,^! may be ( ,plei/oc5e1 or ev5 ( m rec5t date4 ,old] & m deeply erod$ ?an ^! are ! num]\s domes & cones 9 ! t]ritory ( ,haute ,loire4 ,yet m anci5t & /ill m /up5d\sly d5ud$ come ! bosses1 sills & dykes ( ,brita94 ,nev]!less1 ! geologi/1 by ! me?ods s admirably devis$ by ,desm>e/1 may foll[ ! *a9 ( relation%ip ?r\gh ^! diff]5t regions & trace a rem>kable cont9uity ( /ructure4 ,! y\ng] rocks s]ve to illu/rate ! orig9al condition ( ! m anci5t1 :ile ! latt]1 by _! ext5sive d5udation1 p]mit po9ts ( /ructure to be se5 :i* 9 ! =m] are /ill conceal$4 ,no feature 9 ! int]e/+ volcanic di/rict ( ,auv]gne has attract$ m att5tion ?an ! tra*ytic protrusions4#chj ,ris+ conspicu\sly along ! *a9 ( puys1 !y claim notice ev5 f a di/ance ow+ to ! topographical contra/ :i* _! pale r\nd$ domes (f] to ! truncat$1 crat]-be>+ cones ( d>k c9d]s ar\nd !m4 ,!y consi/ ( masses ( a pale v>iety ( tra*yte 7domite71 :i* 9 gr\nd-plan pres5t a circul> or some:at elliptical outl9e4 ,!y v>y 9 size f ! ne>ly circul> dome ( ! ,gr& ,s>c\i1 :i* measures ab\t #djj y>ds 9 diamet]1 to ! l>ge/ mass ( all--t ( ! ,puy de ,dme1 :i* ext5ds = "s #aejj y>ds f nor? to s\? ) a bread? v>y+ f #ejj to #hjj y>ds4 ,!y are likewise prom95t f _! height2 9 ! ,puy de ,dme !y =m ! highe/ elevation ( ! :ole region 7#adfe metres71 & ev5 9 ! less conspicu\s hills !y rise f #ejj to #fjj feet above ! surr\nd+ plateau4 ,footnote #chj3 ,! admirable ,map & ,memoirs ( ,desm>e/ on ,auv]gne are classics 9 geology4 ,scrope's "w1 vol4 i4 p4 #de1 gives /ill ! be/ publi%$ acc\nt ( ?is di/rict4 ,see also ! "w ( ,lecoq 7ibid474 ,! results ( m detail$ petrographical rese>* reg>d+ ! rocks w be f\nd 9 ! essays ( ,m4 ,mi*el ,lvy 7,bull4 ,soc4 ,gol4 ,france1 #ahij1 p4 #fhh7 & 9 ! ,cl]mont %eet ( ! ,geological ,survey ,map ( ,france 7,feuille1 #aff74 ,a bibliography ( ! di/rict up to ! ye> #ahij is giv5 9 ! volume ( ! ,bull4 ,soc4 ,gol4 ,france j cit$1 p4 #fgd4 ,five su* dome-%ap$ protrusions ( tra*yte h made _! appe>ance among ! c9d]-cones 9 a space ( ab\t five ,engli% miles 9 l5g? by ab\t two miles 9 extreme bread?4 ,?\gh op9ions h v>i$ z to ! mode ( =mation ( ^! domes1 !re has be5 a g5]al agreem5t t _! pres5t topographic cont\rs _c be f> f ! orig9al outl9es assum$ by ! masses at ! "t ( _! production4 ,! position ( ! tra*yte bosses among ! puys s]ves to %[ t !y 7 n deep-seat$ masses :i* h be5 entirely uncov]$ by d5udation1 b 7 ess5tially sup]ficial1 & 7 protrud$ to ! surface at v>i\s po9ts along ! plateau 9 ! mid/ ( already exi/+ c9d]-cones4 ,9 "s cases1 !y h ris5 on or ne> ! position ( ! v5ts ( ^! cones4 ,?us ! ,puy de ,*op9e is half encircl$ by ! crat] ( ! ,puy de la ,g\tte1 & ! ,gr& ,s>c\i /&s 9 a simil> relation to ! fragm5t>y crat]-wall ( ! ,petit ,s>c\i4 ,m4 ,mi*el ,lvy1 9 po9t+ out ! sup]ficial "* ( ! domitic protrusions1 has =cibly dwelt on ! evid5ce t ^! rocks h und]gone a comp>atively trifl+ d5udation1 & t !y c\ld nev] h ext5d$ mu* beyond _! pres5t limits4#cha ,z ,scrope po9t$ out1 !y 7 obvi\sly protrud$ 9 a pa/y condition1 n fl[+ out 9 /reams l ! o!r lavas ( ! di/rict1 b consolidat+ )9 _! *imneys & ris+ f ^! 9 r\nd$ domes4 ,footnote #cha3 ,op4 cit4 p4 #gaa4 ,illu/ration3 ,fig4 #cdd4--,section ?r\gh ! ,puy de la ,g\tte & ,puy de ,*op9e4 #a1 ,mica-s*i/2 #b #b1 ,granite2 #c #c1 ,tuffs2 #d1 ,tra*yte2 #e1 ,basalt dyke4 ,und\bt$ly d5udation1 _c h left !m altoge!r unaffect$1 b mu/ h remov$ "s am\nt ( mat]ial f _! surface4 ,!re is reason to believe t ! mat]ial s remov$ may h be5 9 l>ge "p ( a fragm5tal "*1 & t x 0 "u a cov]+ ( loose pyrocla/ic debris t ! upw>d t]m9ation ( ! tra*yte column assum$ its typical dome-=m4 ,?us 9 ! crat]-wall ( ! ,puy de la ,g\tte1 lay]s ( buff-col\r$ tra*ytic tuff dip g5tly away f ! c5tral domite mass ( ! ,puy de ,*op9e4 ,t ?is mat]ial 0 ?r[n out f ! v5t previ\s to ! uprise ( ! domite may be inf]r$ f ! way 9 :i* ! latt] rock has oblit]at$ ! nor!rn half ( ! crat]4 ,! relations ( ! rocks are some:at obscur$ by talus & h]bage1 b :5 ,i la/ visit$ ! locality 9 ! spr+ ( #ahie ! /ructure seem$ to me to be z express$ 9 ! accompany+ diagram 7,fig4 #cdd74chb ,footnote #chb3 ,comp>e ,m4 ,mi*el ,lvy1 ibid4 ,! relative date ( ! protrusion ( ! tra*ytic domes _c be v precisely def9$4 ,!re c1 inde$1 be no d\bt t x belongs to a late phase ( ! volcanic hi/ory4 ,x came long aft] ! outp\r+ ( ! old] basaltic plateaux1 ( :i* l>ge fragm5ts em]ge f beyond ! limits ( ! y\ng] lavas on bo? sides ( ! great ridge ( ! puys1 & n only long aft] t outp\r+1 b ev5 aft] ! widespread %eets ( basalt _h be5 deeply tr5*$ by valleys & isolat$ into outli]s capp+ ! hill-tops4 ,yet !re is good evid5ce also t ! uprise ( ! comp>atively acid tra*ytes 0 n ! la/ volcanic episode ( ! di/rict4 ,! abundance ( d>k slags & fragm5ts ( basalt ly+ on ! domite hills %[s t dis*>ges ( m basic detritus occurr$ aft] ^! hills _h tak5 _! place 9 ! l&scape4 ,s9ce ! late/ eruptions1 a gradual alt]ation ( ! topographical features by d5udation has be5 sl[ly b cont9u\sly go+ on4 ,! ,gr& ,s>c\i1 possibly f hav+ orig9ally _h a consid]able cov]+ ( fragm5t>y mat]ial1 %[s lea/ ! effects ( ?is wa/e4 ,its rem>kably regul> =m1 l t ( an inv]t$ cauldron 7! ,*audron1 z x is call$ 9 ! di/rict71 pres5ts1 9 a di/ant view1 a smoo? grassy surface :i* slopes /eeply d[n into ! great volcanic pla94 ,b on a ne>] exam9ation ^! declivities are f\nd to be seam$ ) tr5*es :i* ! ra9-/orms ( c5turies h dug out4 ,! cov]+ ( loose debris has be5 l>gely wa%$ away1 ?\gh _m fragm5ts ( d>k slag are /ill /rewn ov] ! slopes1 & ! sc>s are n[ be+ cut into ! domite bel[4 ,a m advanc$ /age ( decay may be se5 on ! ,puy de ,dme1 :]e1 f great] elevation & exposure1 ! domite is already deeply ga%$ by gullies & rav9es1 :ile ! slopes bel[ are /rewn ) its detritus4 ,! region ( ! ,velay displays on a f> m ext5sive scale ! protrusion ( tra*ytic & phonolitic bosses1 b z its volcanic hi/ory goes back beyond ! "t ( ! ,puys ( ,auv]gne1 its volcanic monum5ts h consequ5tly be5 m ext5sively affect$ by d5udation4#chc ,a s]ies ( basaltic eruptions =m+ ext5sive %eets c !re be trac$1 ! olde/ dat+ f ,mioc5e "t1 ! y\nge/ com+ d[n to ! age ( ! mammo?1 cave-be> & e>ly man4 ,dur+ ?is prolong$ outp\r+ ( basic lavas !re 7 sev]al int]vals dur+ :i* mat]ials ( a m acid nature--tra*ytes & phonolites--7 erupt$4 ,^! rocks occur p>tly z ext5sive tracts1 cov]+ five or six squ>e miles1 l ^? ( ! ,mez5c1 ! ,megal1 ! ,pic de ,lizieux1 & ! ,r&1 & p>tly 9 isolat$ conical or dome-%ap$ prom95ces1 sometimes only a few hundr$ feet 9 diamet]4 ,upw>ds ( "o hundr$ di/9ct eruptions ( phonolite h be5 obs]v$ 9 ! ,velay4 ,ev5 9 ! tracts :]e !y cov] ! l>ge/ space1 sev]al prom95t em95ces may usually be obs]v$1 n unlike 9 g5]al %ape ! isolat$ cones & domes ( ,auv]gne4 ,9 ^! wid] areas !re appe>s to be evid5ce ( ! outcome ( ! lava f "o or m v5ts1 ei!r z sup]ficial /reams or z und]gr\nd intrusive %eets4 ,m4 ,b\le has express$ 8 op9ion t mo/ ( ! masses ( tra*yte & phonolite h be5 ! result ( local & limit$ eruptions1 ! pa/y rock hav+ ris5 9 & accumulat$ ar\nd its pipe1 )\t fl[+ f> 9 any direction4 ,a section across "o ( ^! masses w\ld pres5t a some:at mu%room-%ap$ =m4#chd ,footnote #chc3 ,9 addition to ! "w ( ,scrope1 ! /ud5t ( ?is important volcanic di/rict w f9d an invaluable guide 9 ! ,le ,puy ,%eet 7,no4 #ahf7 ( ! ,geological ,survey ,map ( ,france1 & 9 ! ,bullet9s ( ! ,survey1 p>ticul>ly ^? by ,,mm4 ,t]mi] & ,b\le1 ,no4 #ac 7#ahij7 & ,no4 #bh 7#ahib74 ,footnote #chd3 ,bull4 ,c>te4 ,gol4 ,france1 ,no4 #bh 7tome iv47 p4 #abe4 ,t fragm5t>y ejections accompani$ ! protrusion ( ^! rocks1 ?\gh probably on a v limit$ scale1 is %[n by ! occasional survival ( portions ( tra*yte tuff ar\nd !m4 ,"o ( ! mo/ notable ( ^! deposits occurs 9 ! holl[ betwe5 ! ,suc du ,p]tuis & ! next dome to ! s\?4 ,x consi/s ( f9e & co>se1 tra*ytic detritus1 :i* 9 "o place is rudely b$d$ & appe>s to dip away f ! phonolite dome beh9d x at an angle ( #cj4 ,?is mat]ial & its incl9ation are :at might be expect$ to occur r\nd an eruptive v5t1 & may be comp>$ ) ^? ( ! crat]-wall ( ! ,puy de la ,g\tte 9 relation to ! domite boss ( ! ,puy de ,*op9e4 ,! d5udation ( ,velay has und\bt$ly advanc$ consid]ably fur!r ?an t ( ! ,puys ( ,auv]gne4 ,! pyrocla/ic mat]ial :i* may h orig9ally cov]$ ! domes ( tra*yte & phonolite has be5 9 great "p swept away4 ,! surr\nd+ rocks1 too1 bo? aque\s & igne\s1 h be5 ext5sively remov$ f ar\nd ! necks ( m endur+ mat]ial4 ,h5ce ! tra*yte & phonolite bosses /& out ) s /rik+ a prom95ce z to arre/ ! eye ev5 = a di/ance ( _m miles4 ,illu/ration3 ,fig4 #cde4--,view ( ! ,hu*e ,po9tue & ,hu*e ,platte we/ ( ,le ,p]tuis4 ,! cone is "o ( ! tra*ytic domes1 :ile ! flat plateau to ! left is a d5ud$ outli] ( ! basalt %eets4 ,!re _c be any d\bt t ^! necks h pi]c$ ! old] basalts1 & !re=e belong to a lat] epo* 9 ! volcanic hi/ory4 ,! approximately horizontal %eets ( basalt h be5 deeply erod$ & r$uc$ to m]e fragm5ts1 & 9 "s in/ances _! exi/+ portions owe _! survival to ! protection af=d$ to !m by ! imm5se protrusions ( m acid mat]ial4 ,b !re is "h1 z well z 9 ,auv]gne1 evid5ce ( ! uprise ( a lat] m basic magma1 = %eets ( basalt are f\nd ov]ly+ "s p>ts ( ! tra*ytes & phonolites4 ,:ile ! ext]nal =ms ( ^! ,velay necks recall ) s+ul> vividness ! features ( _m m anci5t necks 9 ,brita91 an exam9ation ( ! int]nal /ructure ( "s ( !m af=ds "s fur!r int]e/+ po9ts ( resemblance4 ,! slabs into :i*1 by means ( wea!r+ along ! jo9ts1 ! rock is apt to split up are sometimes arrang$ ) a g5]al dip outw>ds f ! c5tre ( ! hill1 s t _! flat surfaces r\ghly co9cide ) ! hillslopes4 ,9 o!r cases ! peculi> platy /ructure1 s *>act]i/ic ( phonolite1 is dispos$ v]tically or dips at a /eep angle into ! hill1 s t ! edges ( ! slabs are pres5t$ to ! declivities1 :i* consequ5tly become m abrupt & rugg$4 ,?\gh none ( ! volcanic s]ies 9 ,auv]gne or ! ,velay is s acid 9 composition z ! m acid memb]s ( ! ,t]ti>y volcanic s]ies ( ,brita91 ! mann] 9 :i* ! tra*ytes & phonolites ( ! ,fr5* region make _! appe>ance pres5ts "s sugge/ive analogies to t ( ! correspond+ rocks 9 ?is c\ntry4 ,we see t !y 7 erupt$ long aft] ! outp\r+ ( ext5sive basaltic plateaux1 t !y belong$ to successive epo*s ( volcanic activity1 t !y 7 protrud$ 9 a pa/y condition to ! surface1 :]e1 m or less cov]$ ) fragm5t>y ejections1 !y t]m9at$ 9 dome-%ap$ hills or spread out to a limit$ di/ance ar\nd ! v5ts1 & la/ly1 t !y 7 succe$$ by a /ill lat] s]ies ( m basic eruptions1 :i* complet$ ! long volcanic hi/ory4 ,we %all see 9 ! foll[+ pages h[ closely ! v>i\s /ages 9 ?is complex record ( volcanic activity may be p>allel$ 9 ! geological records ( ,t]ti>y "t 9 ,brita94#che ,footnote #che3 ,! phonolite necks ( ,bohemia1 :i* =m s prom95t a feature 9 ! ,t]ti>y geology ( t c\ntry1 might likewise be cit$ "h 9 illu/ration ( ! acid domes & bosses ( ! ,briti% ,isles4 ,,*apt] ,,xlvi ,,types ,,( ,,/ructure ,,9 ,,! ,,acid ,,rocks--,,bosses ,return+ n[ to ! consid]ation ( ! acid rocks z ^! manife/ !mselves 9 ! volcanic areas ( ,brita91 ,i w\ld rem>k t ?ree di/9ct types ( /ructure may be not$ among !m1 viz4 7#a7 bosses1 7#b7 sills or intrusive %eets1 7#c7 ve9s & dykes4 ,^! types1 z above rem>k$1 belong entirely to ! und]gr\nd op]ations ( volcanism1 = ?\gh ! rhyolitic fragm5ts 9 ! tuffs & agglom]ates ( ! plateaux prove t acid lavas exi/$ ne> ! surface1 no und\bt$ case ( sup]ficial lava belong+ to ! acid s]ies has yet be5 obs]v$4#chf ,footnote #chf3 ,! rhyolites ( ,t>dree 9 ,antrim h rec5tly be5 claim$ by ,pr(essor ,cole z true lavas gr\p$ r\nd an eruptive v5t4 ,= reasons to be giv5 9 ! next *apt] ,i reg>d !m z intrusive masses1 ?\gh !y may n improbably h be5 connect$ ) /reams ( lava n[ entirely remov$4 ,! bosses ( acid mat]ial 9 ! ,briti% ,t]ti>y volcanic s]ies are irregul> protrusions1 v>y+ 9 size f knobs only a few squ>e y>ds 9 area up to huge masses _m squ>e miles 9 ext5t1 & compris+ gr\ps ( l(ty hills4 ,z a rule1 _! outl9es are m>k$ly irregul>4 ,b5ea? ! surface !y plunge d[n almo/ v]tically ?r\gh ! rocks :i* !y trav]se1 b 9 n a few in/ances _! b\nd>ies are incl9$ to ! horizon1 s t ! contigu\s rocks seem to re/ aga9/ !m1 & sometimes lie 9 outli]s on _! sides & summits4 ,f ! m>g9s ( ^! bosses apophyses are giv5 (f into ! surr\nd+ rocks1 sometimes only r>ely & at wide int]vals1 9 o!r places 9 prodigi\s numb]s4 ,sometimes ! acid mat]ial has be5 inject$ 9 ?\s&s ( ve9s & m9ute ?reads1 :i* completely enclose fragm5ts ( ! surr\nd+ rock4 ,! rock ( :i* ! bosses consi/ is g5]ally granophyric 9 texture1 pass+ on ! "o h&1 p>ticul>ly 9 ! c5tral p>ts1 into granite1 & on ! o!r1 & especially t[>ds ! m>g91 into v>i\s m compact felsitic v>ieties1 & sometimes exhibit+ along ! out] edge m or less develop$ sph]ulitic & fl[-/ructures4 ,decid$ contact metamorphism is traceable r\nd ! bosses1 b is by no means uni=m ev5 9 ! same rock1 "s p>ts be+ highly alt]$1 :ile o!rs1 expos$ app>5tly to ! same influ5ces1 h und]gone little *ange4 ,! mo/ m>k$ examples ( ?is metamorphism are ^? 9 :i* ! ,cambrian lime/one ( ,skye has be5 conv]t$ into a pure :ite sac*>oid m>ble4 ,b ! mo/ int]e/+ to ! /ud5t ( volcanic action are ^? :]e ! alt]$ rocks are old] p>ts ( ! volcanic s]ies4 ,z ! bosses ( ea* volcanic area (f] di/9ctive peculi>ities !y w "h be describ$ geographically4 i4 ,,! ,,acid ,,bosses ,,( ,,skye ,x is 9 ! isl& ( ,skye t ! granophyre & granite bosses atta9 _! l>ge/ dim5sions & af=d1 on ! :ole1 ! mo/ complete evid5ce ( _! /ructures & _! relations to ! o!r p>ts ( ! volcanic s]ies 7,map ,,vi474 ,!y cov] !re a total area ( ab\t #be squ>e miles1 & =m *>act]i/ic gr\ps ( hills f #bjjj to #bejj feet 9 height4 ,on ! s\?-ea/ side1 ?ree conspicu\s cones 7! ,r$ ,hills7 rise f ! valley ( ,/ra? 7,be9n ,de>g ,mhor1 ,be9n ,de>g ,bheag & ,be9n na ,cailli*74 ,a solit>y graceful po9t$ cone 7,be9n na ,cro7 /&s betwe5 ,/ra?more & ,/ra?beg1 :ile to ! nor?-we/ a cont9u\s *a9 ( connect$ cones runs f ,lo* ,sliga*an up into ! he>t ( ! ,cuill9 ,hills4 ,_! conical outl9es1 _! smoo? declivities1 m>k$ ) long div]g+ l9es ( screes1 & _! pale r$di% or r$di%-yell[ hue1 t deep5s aft] a %[] into gl[+ orange1 m>k (f ^! hills f all ! surr\nd+ em95ces1 & =m 9 especial a s+ul> contra/ to ! black1 spiry1 & rugg$ cont\rs ( ! gabbro heights to ! we/ ( !m4 ,besides ?is l>ge cont9u\s mass1 a numb] ( m9or bosses are scatt]$ ov] ! di/rict4 ,( ^! ! l>ge/ =ms ! ridge ( ,be9n an ,dubhai*1 s\? ( ,lo* ,kil*ri/4 ,sev]al m9or protrusions lie betwe5 t ridge & ! flank ( ,be9n ,de>g4 ,o!rs protrude ?r\gh ! moory gr\nd above ,corry2 sev]al occur on ! side ( ! ,s\nd ( ,scalpa1 ab\t ,/rollamus2 & "o1 already ref]r$ to1 lies at ! ea/]n base ( ,bla? ,bhe9n4 ,9 ! neighb\r+ isl& ( ,raasay1 a l>ge area ( granophyre likewise occurs1 :i* w be describ$ ) ! ,sills 9 lat] pages4 ,9 s ext5sive a di/rict !re is room = consid]able div]sity ( composition & texture among ! rocks4 ,z already /at$1 9 "s places1 m p>ticul>ly 9 ! c5tral p>ts ( ! hills1 ! acid mat]ial assumes ! "* ( a granite1 be+ made up ( a holocry/all9e aggregate ( qu>tz1 or?oclase1 plagioclase1 hornbl5de & biotite1 )\t granophyric /ructure1 & ?us becomes a hornbl5de-biotite-granite 7qu>tz-sy5ite1 granite-sy5ite ( ,zirkel1 or amphibole-granitite ( ,ros5bus*74 ,by ! developm5t ( ! micropegmatitic /ructure & radiat$ sph]ical concretions1 x passes into granophyre4 ,by ! appe>ance ( a felsitic gr\ndmass1 x %ades (f into diff]5t v>ieties ( qu>tz-porphyry or rhyolite1 sometimes ) di/9ct bi-pyramidal cry/als ( qu>tz4#chg ,?is *ange1 :i* "h & !re is obs]vable along ! edge ( a boss1 is sometimes accompani$ ) an ample developm5t ( sph]ulitic & fl[-/ructures4 ,z x is conv5i5t to adopt "s g5]al t]m to express ! :ole s]ies ( v>ieties1 ,i h us$ ! ^w granophyre = ?is purpose4 ,footnote #chg3 ,! be/ acc\nt yet publi%$ ( ^! v>ieties 9 ,skye is t by ,pr(4 ,zirkel1 ,zeits*4 ,deuts*4 ,geol4 ,gesells*4 xxiii4 7#ahga7 p4 #hh4 ,illu/ration3 ,fig4 #cdf4--,view ( ,glami*1 #becg feet1 ,gl5 ,sliga*an4 7,f a photograph by ,r4 ,j4 ,a4 ,b]ry1 ,m4,d41 l5t by ! ,scotti% ,m\nta9e]+ ,club74 ,t ! l>ge area ( ^! rocks 9 ,skye 0 ! result ( _m sep>ate protrusions f di/9ct c5tres ( emission may be inf]r$1 ,i ?9k1 n only f ! v>ieties ( petrographical "* 9 ! mat]ial1 b also f ! peculi> topography ( ! gr\nd1 & p]haps f ! curi\s relation :i* seems1 9 "s in/ances at lea/1 to be traceable betwe5 ! ext]nal features & app>5t int]nal /ructure ( ! hills4 ,x w be se5 f ! ,map 7,no4 ,,vi47 t 9 ! area ly+ to ! ea/ ( ,/ra? ,m ! granophyre is brok5 up into ne>ly deta*$ portions by int]v5+ pat*es ( old] rocks4 ,!re c be little d\bt t ! mass ( ,be9n na ,cailli* & ! two ,be9n ,de>gs is ! product ( a di/9ct orifice1 if n ( m ?an "o4 ,be9n na ,cro1 ly+ betwe5 its two deep b\nd+ gl5s1 is ano!r protrusion4 ,! we/]n cones /& s closely toge!r t _! screes meet at ! bottoms ( ! int]v5+ valleys4 ,yet ea* gr\p is n improbably ! result ( emission f an indep5d5t funnel1 l ! sep>ate domite puys ( ,auv]gne4 ,b1 ?\gh ,i believe ?is l>ge area ( granitoid rock to h proce$$ n f "o b f _m orifices1 ,i h only "h & !re obta9$1 f ! individual hills !mselves1 indications ( an int]nal /ructure sugge/ive ( di/9ct & successive protrusions ( mat]ial f ! same v5t ( dis*>ge4 ,on ! out] declivities ( "s ( ! cones we may detect a rudely b$d$ /ructure1 :i* w be subsequ5tly ref]r$ to z well display$ 9 ,rum 7p4 #djc74 ,?is /ructure is specially obs]vable along ! ea/ side ( ,gl5 ,sliga*an4 ,d[n ! nor!rn slopes ( ,m>sco ! granophyre 7"h 9 "p a hornbl5de-biotite-granite7 is dispos$ 9 massive %eets or b$s t plunge outw>ds f ! c5tre ( ! hill at angles ( #cj to #dj4 ,on ! s\!rn front ( ! same graceful cone1 z well z on ! flanks ( its neighb\r1 ,ruadh ,/ac1 /ill pla9] indications ( a def9ite arrangem5t ( ! mass ( ! rock 9 irregul> l5ticul> b$s may be notic$4 ,^! b$s1 fold+ ov] ! axis ( ! hill1 dip /eeply d[n z conc5tric coats ( rock4 ,! ext]nal resemblance ( ! r$ conical m\nta9s ( ,skye to ! tra*yte puys ( ,auv]gne 0 long ago rem>k$ by ,j4 ,d4 ,=bes1#chh & 9 ?is int]nal arrangem5t ( _! mat]ials1 indef9ite ?\gh x may be1 !re is a fur!r resemblance to ! onion-l coat+s :i* ,von ,bu* & ,scrope rem>k$ 9 ! /ructure ( ! int]ior ( ! ,gr& ,s>c\i4#chi ,footnote #chh3 ,ed94 ,new ,phil4 ,j\r4 xl4 p4 #gh4 ,footnote #chi3 ,von ,bu*1 ,geogno/is*e ,beoba*tung5 auf ,reis5 dur* ,deuts*l& und ,itali51 vol4 ii4 7#ahji7 p4 #bde2 ,scrope1 ,geology & ,ext9ct ,volcanoes ( ,c5tral ,france1 #bnd edit4 p4 #fh4 ,von ,bu* reg>d$ ! ext]nal =m ( ?is ,puy z hav+ be5 det]m9$ by its int]nal /ructure4 ,:]e ! cont\r ( ! cones is regul>1 & ! declivities are n m>k$ by prom95t sc>s & ribs ( rock1 ?is monotony ( feature betok5s a correspond+ uni=mity ( petrographical "*4 ,b :]e1 on ! o!r h&1 ! slopes are div]sifi$ by project+ crags & o!r v>ieties ( outl9e1 a great] range ( texture & composition 9 ! mat]ial ( ! hills is indicat$4 ,?is relation is well br\ght out on ! we/]n front ( ,m>sco1 :]e num]\s alt]nations ( granitoid & felsitic textures occur4 ,on _m declivities also1 :i* at a di/ance look q smoo?1 b :i* are really r\gh ) angul> blocks deta*$ f ! p>5t mass und]nea?1 an occasional basalt-dyke w be obs]v$ to rise z a prom95t d>k rib4 ,a good example ( ?is /ructure is to be se5 on ! s\? front ( ,be9n na ,cailli*4 ,:]e a gr\p ( d>k p>allel dykes runs along ! sides ( "o ( ^! pale cones1 x sometimes produces a curi\sly deceptive appe>ance ( b$d+4 ,a conspicu\s illu/ration may be notic$ on ! s\!rn front ( ,be9n ,de>g ,meadhona*1 nor? f ,m>sco4 ,:5 ,i fir/ saw t hillside ,i c\ld n realize t ! p>allel b>s 7 actually dykes until ,i _h cross$ ! valley & climb$ ! slopes ( ! hill4#cij ,footnote #cij3 ,! diff]5ce ( cont\r & col\r betwe5 ! ord9>y r$di% smoo?-slop$ sy5ite & ! black craggy hyp]/h5e rock & gre5/one 9 ! ,glamaig gr\p ( hills caught ! eyes ( ,von ,oeynhaus5 & ,von ,de*5 7,k>/5's ,ar*iv1 i4 p4 #hc74 ,good evid5ce ( successive protrusions ( ! acid rock )9 ! great area ( ! ,r$ ,hills may be f\nd on ! s\? side ( ,meall ,de>g at ! head ( ,gl5 ,sliga*an1 :]e ! granophyre is trav]s$ by a y\ng] b& or dyke ( f9e-gra9$ sph]ulitic mat]ial ab\t t5 feet broad4 ,! rock exhibits !re ! same beautiful fl[-/ructure ) r[s ( sph]ulites z is to be se5 along ! contact ( ! ma9 granophyre mass ) ! gabbro on ! same hill1 :i* w be aft]w>ds describ$4 ,?is dyke1 ve9 or b&1 ?\gh possibly belong+ to ! same epo* ( protrusion z ! surr\nd+ granophyre1 mu/ obvi\sly be lat] ?an ! consolidation ( ! rock :i* x trav]ses4 ,occasionally r\nd ! m>g9 ( ! granophyre a s+ul> brecciat$ /ructure is to be se54 ,i h f\nd x well m>k$ on wea!r$ faces1 along ! flanks ( ,glamaig & ( ,m>sco1 & ,mr4 ,h>k] has obs]v$ _m examples ( x on ! nor? side ( ! granophyre mass ( ! ,r$ ,hills4 ,:5 ! rock is brok5 op51 x is less easy to detect ! angul> & subangul> fragm5ts f ! surr\nd+ matrix1 :i* is f9ely cry/all9e or felsitic4 ,! actual junction ( ! eruptive mass ) ! surr\nd+ rocks ?r\gh :i* x has asc5d$ is g5]ally a ne>ly v]tical b\nd>y1 b ! granophyre sometimes plunges at a great] or less angle "u ! rocks t lie aga9/ or ^u x4 ,on ! nor? side ( ,glamaig1 = in/ance1 ! prophyritic & felsitic m>g9 ( ! great body ( eruptive rock desc5ds z a /eeply incl9$ wall1 aga9/ :i* ! r$ s&/ones & m>ls at ! base ( ! ,second>y =mations are %>ply tilt$4 ,on ! s\? side ( ! area a simil> /eep face ( f9e-gra9$ rock =ms ! edge ( ! granophyre ( ! great s\!rn cones1 & plunges d[n beh9d ,lias lime/one & %ale1 ,cambrian lime/one & qu>tzite1 or portions ( ! ,t]ti>y volcanic s]ies4 ,:]e ! granophyre cuts v]tically ?r\gh ! gabbro1 ! latt] rock be+ m durable is apt to rise above ! m decomposable granophyre z a crag or wall1 & ?us ! deceptive appe>ance arises ( ! basic ov]ly+ ! acid rock4 ,z above m5tion$1 !re seems e reason to believe t ?is peculi>ity ( wea!r+ has giv5 rise to or confirm$ ! mi/ak5 impression t ! granophyre is old] ?an ! gabbro4 ,!re c be no d\bt1 h[ev]1 t along _m p>ts ( ! b\nd>y-l9e ! acid eruptive mass ext5ds und]nea? ! surface f> beyond ! actual base ( ! cones1 = project+ knobs z well z ve9s & dykes ( x rise up among ! surr\nd+ rocks4 ,?is is well se5 along ! nor!rn foot ( ,be9n na ,cailli*4 ,b ( all ! ,skye bosses none exhibits its l9e ( junction ) ! surr\nd+ rocks s well & cont9u\sly z ,be9n an ,dubhai*4 ,?is isolat$ tract ( eruptive mat]ial lies entirely )9 ! area ( ! ,cambrian lime/one1 & its actual contact ) t rock1 & ) ! basalt-dykes t trav]se x1 c be exam9$ almo/ ev]y:]e4 ,! junction is usually v]tical or ne>ly s1 sometimes incl9+ outw>ds1 sometimes inw>ds4 ,x is not*$ & wavy1 ! granite s5d+ out project+ spurs or ve9s1 & retir+ into little bays1 :i* are occupi$ by ! lime/one4 ,! subdivisions ( ! latt] rock h rec5tly be5 trac$ by ,mr4 ,h>k] up to "o side ( ! granite & recogniz$ aga9 on ! o!r side1 ) no app>5t displacem5t1 z if s mu* lime/one _h be5 pun*$ out to make way = ! uprise ( ! acid boss4 ,! old] dykes1 too1 are cont9u\s on ei!r side ( ! ridge4 ,! granite is massive & jo9t$1 splitt+ up into great quadrangul> blocks l an anci5t granite1 & wea!r+ into r\nd$ b\ld]s4 ,its granitic composition & texture are be/ se5 :]e ! mass is broade/1 s\? ( ,kilbride4 ,t[>ds its m>g91 on ! %ore ( ,camas ,malag1 ! granophyric /ructure appe>s1 especially 9 n>r[ ribbons or ve9s t run ?r\gh ! m granitic p>ts ( ! rock4 ,^! may be comp>$ ) ! mu* l>g] dyke ( sph]ulitic rock above notic$ z trav]s+ ! granophyre ( ,meall ,de>g4 ,illu/ration3 ,fig4 #cdg4--,section across ! nor? slope ( ,be9n an ,dubhai*1 ,skye4 a a1 ,cambrian lime/one2 b b1 basalt dykes2 c1 granite4 ,imm$iately to ! s\? ( ,camas ,malag ! junction ) ! lime/one is well display$1 & ! eruptive rock1 :i* is !re granitic 9 "*1 s5ds out into ! lime/one a ve9 or dyke ab\t two feet broad1 ( clos] gra9 ?an ! ma9 body ( ! boss1 b /ill di/9ctly granitic 9 /ructure4 ,! junction on ! nor? side is equally well se5 bel[ ! cr(ts ( ,torran4 ,"h ! rock ( ! boss1 = a few y>ds f its m>g91 assumes a f9e-gra9$ felsitic aspect1 & "u ! microscope pres5ts a curi\s brecciat$ appe>ance1 sugge/ive ( its hav+ brok5 up at ! m>g9 be=e f9al consolidation4 ,portions ( ! already cry/alliz$ granite seem to be involv$ 9 a microgranitic base4 ,! rock has "h truncat$ a numb] ( basalt-dykes :i* int]sect ! ,cambrian lime/one4 ,to "o ( ^! fur!r ref]5ce w be made 9 ! sequel4 ,on ! surface ( ! mass ( ,be9n an ,dubhai*1 a few little pat*es ( lime/one occur to ! s\? ( ,kil*ri/ ,lo*4 ,consid]+ ! ne>ly v]tical wall :i* ! granophyre pres5ts to ! adjac5t rock all r\nd its m>g91 we may p]haps reasonably inf] t ^! outli]s ( lime/one are remnants ( a once cont9u\s lime/one %eet t ov]lay ! eruptive rock1 & h5ce t1 ) due all[ance = consid]able d5udation1 ! pres5t surface ( ! boss repres5ts approximately ! upp] limit to :i* ! granophyre asc5d$ ?r\gh ! lime/one4 ,! actual facts are %[n 9 ,fig4 #cdg4 ,all r\nd ! m>g9 ( ?is boss1 ! lime/one has be5 conv]t$ = a v>iable di/ance ( a few feet or _m y>ds into a granul> cry/all9e m>ble4 ,! light] portions ( ! lime/one h become sn[y :ite2 b "s ( ! d>k] c>bonace\s b$s reta9 _! d>k t9t4 ,! nodules ( *]t1 abundant 9 _m ( ! lime/ones1 project f ! wea!r$ faces ( ! m>ble4 ,! dolomitic portions ( ! s]ies h likewise und]gone alt]ation into a ?or\ghly cry/all9e-granul> or sac*>oid rock4 ,! mo/ ?or\gh metamorphism is exhibit$ by portions ( ! lime/one :i* are completely surr\nd$ by & re/ ^u ! granite4 ,! l>ge/ ( ^! ov]ly+ pat*es 0 _m ye>s ago qu>ri$ = :ite m>ble above ! old ,manse ( ,kil*ri/4 ,i h %[n by li?ological1 /ratigraphical & palontological evid5ce t ?is lime/one1 in/ead ( belong+ to ! ,lias1 z 0 =m]ly believ$1 =ms a "p ( ! ,cambrian or possibly ! v l[e/ ,silurian s]ies1 be+ a cont9uation ( ! fossilif]\s lime/one ( we/]n ,su!rl& & ,ross-%ire4#cia ,mr4 ,cl\gh & ,mr4 ,h>k]1 9 ! progress ( ! ,geological ,survey 9 ,skye1 h asc]ta9$ t ! di/9ctive *>act]s ( ! ?ree gr\ps ( /rata into :i* ! lime/one c be divid$ may be recogniz$ ev5 ?r\gh ! mid/ ( ! metamorphism4#cib ,footnote #cia3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xliv4 7#ahhh7 p4 #fb4 ,footnote #cib3 ,annual ,report ( ,director-,g5]al ( ! ,geological ,survey = #ahie4 ,! g5]ally v]tical l9e ( sep>ation betwe5 ! rock ( ,be9n an ,dubhai* & ! contigu\s lime/one has be5 tak5 advantage ( = ! segregation ( m9]al ve9s4 ,on ! s\!rn b\nd>y at ,camas ,malag1 a gre5i% fl9ty lay]1 f less ?an an in* to two or ?ree in*es 9 wid?1 consi/+ ( a f9ely-granul> aggregate ( "s ne>ly col\rless m9]al1 :i* pol>izes brilliantly1 coats ! wall ( ! granophyre1 & also bo? sides ( ! ve9 :i* proce$s f t rock into ! lime/one4 ,b ! mo/ abundant & int]e/+ deposits are metallif]\s4 ,fragm5ts ( a k9d ( gossan may be notic$ all along ! b\nd>y-l9e ( ! boss1 & among ^! are pieces ( magnetic iron-ore & sulphides ( iron & copp]4 ,! magnetite may be se5 9 place imm$iately to ! s\? ( ,kilbride4 ,a mass ( ?is ore sev]al feet 9 diamet] s5ds /r+s & dissem9at$ p>ticles ?r\gh ! surr\nd+ granophyre1 & is p>tially coat$ along its jo9ts ) gre5 c>bonate ( copp]4 ,f ! ,skye area important evid5ce is obta9able 9 reg>d to ! relation ( ! acid eruptions to 7#a7 e>li] eruptive v5ts fill$ ) agglom]ate2 7#b7 ! b$d$ basalts ( ! plateaux2 7#c7 ! bosses1 sills & dykes ( gabbro & dol]ite2 & 7#d7 ! great sy/em ( basic dykes4 7#a7 ,relation ( ! ,granophyre to old] ,eruptive ,v5ts4--,! granophyre ( ,be9n na ,cailli* & ! two ,be9n ,de>gs has invad$ on its nor?-ea/]n side ! ,cambrian lime/one & qu>tzite1 & has truncat$ ! %eets ( intrusive dol]ite & gabbro t h !re be5 inject$ into !m4 ,b to ! s\?-we/ x rises ?r\gh ! great ,/ra? agglom]ate already describ$1 & cont9ues 9 t rock r\nd to ! entrance into ,/ra? ,beg4 ,! eruptive mass is 9 great "p surr\nd$ ) a r+ ( agglom]ate1 z if x _h ris5 up a huge volcanic *imney & solidifi$ !re1 ?\gh probably !re 7 m ?an "o v5t 9 ?is agglom]ate area4 ,aga9 ! ?ick mass ( agglom]ate nor? ( ,belig is int]pos$ betwe5 ! b$d$ lavas & ! great granophyre mass :i* ext5ds nor?w>ds to ,lo* ,sliga*an4 ,on ! we/ side ( ! ,blav5 ridge1 a numb] ( masses ( agglom]ate are f\nd on bo? sides ( ,gl5 ,sliga*an1 along ! bord] ( ! same great tract ( acid rock4 ,illu/ration3 ,fig4 #cdh4--,section f ,be9n ,de>g to ,be9n an ,dubhai*1 ,skye4 a a1 ,cambrian lime/one2 b b1 volcanic agglom]ate2 c c c1 basalt-dykes old] ?an granophyre2 d#a1 granophyre ( ,be9n ,de>g2 d#b1 granophyre 9 ! agglom]ate neck2 d#c1 granite ( ,be9n an ,dubhai*2 e1 basalt-dyke y\ng] ?an granite4 ,) reg>d to ! relation ( ! granophyre ( ! ,r$ ,hills to ! great agglom]ate ( ,/ra?1 we may inf] t ! granophyre has n ris5 exactly 9 ! c5tre ( ! old funnel1 b r to ! nor? ( x1 unless we suppose1 z already sugge/$1 t "s ( ! agglom]ate belongs to ! cone t ga!r$ r\nd ! eruptive orifice4 ,x is int]e/+ to obs]ve1 h[ev]1 t granophyre1 f ! same or f ano!r c5tre ( protrusion1 has likewise ris5 along ! out] or s\!rn m>g9 ( ! agglom]ate1 g5]ally betwe5 t rock & ! lime/one1 b sometimes entirely )9 ! agglom]ate4 ,! di/ance betwe5 ! ne>e/ "p ( ?is r+ ( eruptive rock & ! edge ( ! boss ( ,be9n an ,dubhai* is "u #djj y>ds1 ! int]v5+ space be+ occupi$ by lime/one 7or m>ble71 mu* trav]s$ by nor?-we/ basalt-dykes4 ,mo/ ( ^! dykes d n ent] ! rocks ( ! v5t1 & are abruptly truncat$ by ! mass ( ,be9n an ,dubhai*4 ,! probable /ructure ( ?is locality is %[n 9 ,fig #cdh4 ,! masses ( agglom]ate :i* fur!r we/w>d s curi\sly foll[ ! m>g9 ( ! great granophyre bosses1 & ^? :i* are entangl$ 9 t rock & 9 ! gabbro1 probably indicate1 z already sugge/$1 ! position ( a gr\p ( old] volcanic funnels :i* provid$ facilities = ! uprise ( ! basic & acid magmas4 ,! gr\p ( v5ts :i*1 z we h se51 probably rose out ( ! plateau-basalts1 & fir/ s]v$ = ! rise ( ! masses ( gabbro1 has by ! subsequ5t protrusion ( ! granophyres be5 /ill fur!r de/roy$ & conceal$4 ,! granophyre intrusions 9 ! great ,/ra? agglom]ate h lately be5 mapp$ & describ$ by ,mr4 ,h>k]4 ,z reg>ds _! int]nal /ructure & composition1 ?is obs]v] rem>ks t comp>$ ) ! normal granophyres ( ! ,r$ ,hills & o!r bosses ( ! di/rict1 ^! small] intrusive masses are d>k] & manife/ly ri*] 9 ! iron-be>+ m9]als1 & h a slightly high] specific gravity4 ,b 9 _! g5]al *>act]s !y agree ) ! o!r granophyres4 ,! mo/ int]e/+ feature 9 !m is ! evid5ce !y af=d t !y h enclos$ & p>tially dissolv$ fragm5ts ( basic rocks4 ,to ?is evid5ce fur!r ref]5ce w be made on a lat] page 7see p4 #cib74 7#b7 ,relation ( ! ,granophyre to ! ,b$d$ ,basalts ( ! ,plateaux4 ,metamorphism ( ! ,basalts4--,on ! nor?-we/ side1 ! granophyre ( ,glamaig & ,gl5 ,sliga*an m\nts directly out ( ! b$d$ basalts4 ,^! latt] rocks1 :i* rise into *>act]i/ic t]rac$ slopes on ! nor? side ( ,lo* ,sliga*an1 appe> on ! s\? side imm$iately to ! we/ ( ,scons]1 & /ret* we/w>ds r\nd ! roots ( ,glamaig into ! ,coire na ,sgairde4 ,z !y approa* t hill !y assume ! usual dull1 indurat$1 spl9t]y1 ve9$ "* ( _! contact metamorphism1 & wea!r ) a pale cru/4 ,"s ( !m are highly amygdaloidal1 & betwe5 _! successive b$s ?9 b&s ( basalt-breccia1 also mu* h>d5$1 occasionally appe>4 ,ve9s ( granophyre become m num]\s ne>] ! ma9 mass ( t rock4 ,! actual l9e ( junction runs into ! ,coire na ,sgairde & slants up ! ,druim na ,ruaige1 asc5d+ to )9 a few feet ( ! top ( t ridge4 ,a d>k basic rock lies on ! granophyre1 ! latt] be+ "h f9] gra9$ & gre5i% 9 col\r1 & project+ up into ! =m]4#cic ,!re is s mu* detritus along ! sides & floor ( ,gl5 ,sliga*an t ! relations ( ! two gr\ps ( rock _c be well exam9$ !re4 ,b ! basalts1 :i* pres5t _! ord9>y *>act]s to ! nor? ( ! ,inn1 are obs]v$ to become m & m indurat$1 close-gra9$1 dull & spl9t]y1 z !y draw ne>] to ! granophyre ( ,m>sco4 ,?is "p ( ! di/rict furni%es ! cle>e/ evid5ce ( ! po/]iority ( ! great cones ( ,glamaig & its neighb\rs to ! plateau-basalts :i* come up to ! v base ( ^! hills4#cid ,footnote #cic3 ,i ?9k x probable t "s ( ! gre5i% portions ( ! granophyre along ?is "p ( ! junction-l9e w be f\nd to h _h _! /ructure & composition alt]$ by hav+ incorporat$ into _! sub/ance a proportion ( ! b$d$ basalts ?r\gh :i* !y h be5 disrupt$4 ,footnote #cid3 ,! dykes ( granophyre 9 ^! basalts are ref]r$ to at p4 #ddd4 ,r\nd ! ea/]n gr\p ( cones "s int]e/+ fragm5ts ( ! once cont9u\s %eet ( plateau-basalts rema91 & %[ ! same relation ( ! acid protrusions on t side4 ,"o ( ^! lies on ! granophyre ( ! flanks ( ,be9n na ,cailli*1 a little to ! we/ ( ! lo* at ! nor!rn base ( t hill4 ,ano!r ( l>g] size =ms a prom95t knob ab\t ?ree-qu>t]s ( a mile fur!r we/1 & is prolong$ into ! huge d>k excresc5ce ( ,creagan ,dubha1 :i* rises 9 su* /rik+ contra/ to ! smoo? r$ declivities ( ! granophyre cones ar\nd x4 ,?is prom95ce at its ea/]n & nor!rn p>ts consi/s ( highly indurat$ spl9t]y basalt 9 di/9ct b$s1 "s ( :i* are /rongly amygdaloidal4 ,! b$d+ is ne>ly v]tical1 b ) an incl9ation inw>ds to ! hill4 ,t[>ds ! s\?-we/ end a ?9 b& ( basalt-breccia makes its appe>ance betwe5 two b$s ( basalt4 ,its ?ickness rapidly increases s\?w>d until x is ! only rock adh]+ to ! granophyre4 ,beyond ! foot ( ! hill1 lime/one & qu>tzite occupy = "s di/ance ! bottom ( ,/ra? ,beg1 mu* invad$ by masses ( qu>tz-porphyry4 ,at ! summit ( ,creagan ,dubha abundant ve9s run into ! basic rocks f ! granophyre1 :i* is "h f9] gra9$ t[>ds ! m>g92 & !re are likewise ve9s ( qu>tz-porphyry :i*1 ?\gh _! actual connection ) ! ma9 mass ( granophyre _c be se51 are no d\bt apophyses f x4 ,?is outli] ( alt]$ basalt & breccia appe>s to me to be a fragm5t ( ! plateau-basalts :i* once ov]lay ! ,cambrian & ,jurassic rocks ( ,/ra? ,beg1 & 7 disrupt$ by ! uprise ( ! granophyre4 ,x cont9ues to adh]e to ! wall ( ! eruptive mass t broke up & bak$ its rocks4 ,its breccia1 pass+ s\?w>d into a co>se agglom]ate1 may be a product ( ! same v5t or gr\p ( v5ts t dis*>g$ ! great agglom]ate mass above ,kilbride & ,kil*ri/4 ,i h already 7p4 #bhb7 ref]r$ to :at appe>s to be ano!r outli] ( ! basalts on ! s\? side ( ,be9n ,de>g4 ,on ! nor!rn & s\!rn flanks ( ,be9n na ,cro1 simil> evid5ce may be obs]v$ ( ! po/]iority ( ! granophyre to ! basic rocks4 ,r\nd ! nor!rn base ( ! hill a cont9u\s tract ( plateau-basalts1 dol]ites & gabbros =ms ! ridge betwe5 ,/ra?more & ,/ra?beg4 ,!re is an admirable section ( ! relation ( ! two gr\ps ( rock on ! ea/]n side ( ! we/]n gl54 ,along ! l[] "p ( ! declivity1 co>sely-cry/all9e gabbros1 l "s ( ^? 9 ! ,cuill9 ,hills1 are succe$$ by %eets ( dol]ite & basalt1 ! :ole =m+ an asc5d+ succession ( b$s to ! summit ( ! ridge4 ,! edges ( ^! b$s are obliquely truncat$ by ! body ( granophyre1 :i* slants up ! hill across !m & s5ds ve9s into !m4 ,!y are fur!r trav]s$ by basalt dykes1 :i* "h1 z almo/ ev]y:]e1 ab\nd 7,fig4 #cdi74 ,on ! s\? side ( ,be9n na ,cro1 highly indurat$ black & grey ,lias %ales & s&/ones h be5 tilt$ up /eeply & indurat$ by ! eruptive rock ( ! hill2 & at "o place "s #hjj feet above ! sea1 a little pat* ( alt]$ basalt1 ly+ on ! %ale1 b close up aga9/ ! /eep declivity ( granophyre1 =ms a conspicu\s prom95ce on ! o!rwise featureless slope4 ,ref]5ce has already be5 made to ! mass ( f9e-gra9$ hornbl5de-granite :i* runs = sev]al miles at ! base ( ! volcanic s]ies on ! ea/]n side ( ! ,blav5 gr\p ( hills4 ,mr4 ,h>k] has trac$ a great developm5t ( granophyre on ! we/ side ( ^! hills1 :]e ! acid rock s5ds apophyses bo? into ! b$d$ basalts & into ! gabbros4 ,illu/ration3 ,fig4 #cdi4--,section at nor? end ( ,be9n na ,cro1 ,skye4 a1 basalt1 dol]ite & gabbro2 b1 granophyre ( ,be9n na ,cro2 b1 dyke ( granophyre2 c c1 basalt dykes4 ,comb9+ ! results ( obs]vations made n only 9 ,skye b 9 ,mull1 ,rum & ,ardnamur*an1 ,i %all "h give a full] acc\nt ( ! metamorphism ( ! basalts1 to :i* frequ5t allusion has be5 made z "o ( ! evid5ces ( ! po/]iority ( ! eruptive bosses ( rock r\nd :i* x occurs4#cie ,! field-geologi/ obs]ves t ! basalts1 z !y are trac$ t[>ds ^! bosses1 lose _! usual ext]nal *>act]s4 ,!y no long] wea!r into sph]oidal blocks ) a ri* br[n loam1 b project 9 mu* jo9t$ crags1 & _! h>d rugg$ surface %[s :5 brok5 a ?9 :ite cru/1 b5ea? :i* ! rock appe>s black or d>k blui%-grey1 dull & spl9t]y4 ,!y are g5]ally ve9$ ) m9ute ?reads or /r+s ( calcite1 epidote & qu>tz1 :i* =m a yell[i%-br[n network t projects above ! re/ ( ! wea!r$ surface4 ,:]e !y are amygdaloidal1 ! k]nels no long] decay away or drop out1 leav+ ! empty smoo?-surfac$ cells1 b rema9 z if !y graduat$ into ! surr\nd+ rock by an int]lac+ ( _! cry/all9e con/itu5ts4 ,!y !n look at a di/ance m l spots ( decoloration1 & ev5 :5 se5 close at h& w\ld h>dly at fir/ betray _! real nature4 ,footnote #cie3 ,_m ye>s ago ,i 0 mu* /ruck ) ! evid5ce ( alt]ation 9 ! igne\s rocks ( ,mull1 & ref]r$ to x 9 sev]al pap]s1 ,proc4 ,roy4 ,soc4 ,ed94 7#ahff-fg7 vol4 vi4 p4 #gc2 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxvii4 7#ahga7 p4 #bhb1 note4 ,! subject 0 m fully discuss$ 9 my memoir 9 ! ,trans4 ,roy4 ,soc4 ,ed94 vol4 xxxv4 7#ahhh7 p4 #afg1 f :i* ! acc\nt 9 ! text is tak54 ,pr(4 ,judd has m rec5tly ref]r$ ! alt]ation to solfat>ic action 7,qu>t4 ,j\rn4 ,geol4 ,soc4 xlvi4 #ahij1 p4 #cda74 ,z already m5tion$1 ,i h be5 unable to detect evid5ce ( su* action4 ,! alt]ation is always intimately connect$ ) ! pres5ce ( intrusive masses1 & x affects indiff]5tly any "p ( ! basalt-plateaux :i* may *ance to lie next to ^! masses4 ,! b$d$ lavas c be trac$ /ep by /ep f _! usual unalt]$ condition 9 ! plateaux to _! metamorphos$ /ate next to ! eruptive rocks4 ,! nature or degree ( ! metamorphism has d\btless some:at v>i$ ) ! composition & /ructure ( ! rocks affect$1 & ) ! "* & mass ( ! eruptive mat]ial2 b x is c]ta9ly n conf9$ to ! old] p>ts ( ! plateaux1 nor to any suppos$ pre-basaltic gr\p ( &esites4 ,i h f\nd no evid5ce t su* a gr\p any:]e prec$$ ! plateau-basalts4 ,! &esites1 s f> at lea/ z my obs]vations g1 7 erupt$ at int]vals dur+ ! plateau p]iod1 & alt]nate ) ! true basalts4 ,! greate/ accumulation ( !m lies n bel[ b above ! g5]al body ( ! basalts1 9 ! pale gr\p ( ,mull4 ,nor ev5 if ! t]m propylite be adopt$ = ^! alt]$ rocks1 c x be appli$ to any special horizon 9 ! volcanic s]ies4 ,! alt]ation ( ! basic rocks by ! granophyre ( ,/4 ,kilda w be describ$ 9 ! acc\nt ( t isl& 9 ,*apt] xlvii4 ,f ! specim5s collect$ by me among ! ,inn] ,hebrides up to ! ye> #ahhh1 ,i select$ two doz5 :i* seem$ to be fairly typical ( ^! alt]$ rocks1 & plac$ ?9 slices ( !m = microscopic exam9ation 9 ,dr4 ,hat*'s h&s4 ,8 notes may be cond5s$ into ! foll[+ summ>y4 ,"o ( ! mo/ frequ5t features 9 ! slides is ! t5d5cy 9 ! compon5t m9]als to assume granul> =ms4 ,9 "o specim5 f ,lo* ,spelve1 ,mull1 ! rock1 probably orig9ally a dol]ite1 %[s only a few isolat$ recognizable cry/als ( plagioclase & augite1 ! :ole ( ! re/ ( ! rock consi/+ ( r\ndi% granules emb$d$ 9 a felspa?ic matrix4 ,! felsp> cry/als are sometimes brok5 up into a mosaic1 ?\gh reta9+ _! ext]nal cont\rs4 ,besides ! granules1 :i* are no d\bt augite1 a few gra9s ( magnetite are scatt]$ ?r\gh ! rock1 aggregat$ "h & !re into little gr\ps4 ,9 ano!r specim51 tak5 f ! junction ) ! granophyre 9 ,gl5more 9 ! same isl&1 p>ts ( ! augite cry/als are conv]t$ into granul> aggregates associat$ ) l>ge gra9s & pat*es ( magnetite4 ,! latt] m9]al also assumes 9 "s ( ! rocks granul> & ev5 globul> %apes sugge/ive ( fusion4 ,! felsp>s1 :i* 9 mo/ ( ! basic rocks are usually rem>kably cle> & fre%1 %[ m>k$ kaol9ization 9 "s ( ^! alt]$ masses4 ,m9ute dusky scales ( kaol9 are develop$1 sometimes also ) ! sep>ation ( m9ute gra9s ( qu>tz4 ,! augite %[s frequ5t alt]ation to hornbl5de1 proce$+ z usual f ! ext]ior inw>d4 ,9 "s cases only an envelope ( uralite appe>s r\nd ! augite1 :ile 9 o!rs only a k]nel ( ! orig9al m9]al is left1 or ! :ole cry/al has be5 *ang$4 ,9 _m cases ! alt]$ sub/ance appe>s z m9ute ne$les1 blades & fibres ( act9olite4 ,occasionally1 besides ! gre5 hornbl5de1 %r$-l pieces ( a /rongly pleo*roic br[n hornbl5de make _! appe>ance4 ,s]p5t9\s & *loritic sub/ances are n infrequ5t4 ,epidote is sometimes abundant4 ,! titanif]\s iron has commonly pass$ m or less completely into leucox5e4 ,"h & !re a d>k mica may be detect$4 ,s9ce ! ye> #ahhh ,i h cont9u$ ! inve/igation ( ?is subject1 & h especially /udi$ ! metamorphism ( ! b$d$ basalts on ! we/]n %ores ( ,lo* ,scavaig1 :]e1 z already describ$1 !y are truncat$ by v]tical b$s ( gabbro1 & are trav]s$ by basalt-dykes & by abundant ve9s ( f9e-gra9$ granophyre4 ,! alt]ation "h effect$ af=ds excell5t mat]ials = /udy1 z ! v same %eets ( basalt c be foll[$ f ! normal conditions outside to ! alt]$ /ate )9 ! influ5ce ( ! metamorphic ag5t4 ,! alt]nations ( amygdaloidal & m compact %eets c /ill be recogniz$1 al?\gh _! enclos$ amygdales h 9 places be5 almo/ effac$4 ,!y %[ ! dull1 indurat$1 spl9t]y "*1 ) ! :ite wea!r$ cru/1 s di/9ctive ( ?is type ( contact-metamorphism4 ,!y are trav]s$ by num]\s sills & ve9s ( gabbro4 ,z has be5 already sugge/$1 al?\gh no l>ge mass ( granophyre appe>s "h at ! surface1 ! alt]ation ( ! basalts is probably to be attribut$ n s mu* to ! influ5ce ( ! gabbro1 z to ! abundant acid sills1 dykes & ve9s1 = !re may be a consid]able body ( granophyre und]nea? ! locality1 ! dykes & ve9s be+ indications ( its vic9ity4 ,9 ! summ] ( #ahie ,i exam9$ ! locality ) mu* c>e1 & collect$ "s typical specim5s illu/rative ( ! conditions ( metamorphism pres5t$ by diff]5t v>ieties ( ! b$d$ basalts4 ,?9 slices cut f ^! specim5s 7 plac$ 9 ,mr4 ,h>k]'s h&s = microscopical exam9ation1 & he furni%$ me ) ! foll[+ notes reg>d+ !m4 ,9 h&-specim5s ! b$d$ basalts f ! neighb\rhood ( ! gabbro ( ,lo* ,scavaig #ffac-ffah d n appe> v diff]5t f ! normal basalts ( ?is region4 ,! mo/ conspicu\s second>y m9]al is yell[i%-gre5 epidote 9 pat*es1 & especially 9 ! amygdales4 ,! texture ( ! rocks v>ies1 & ! slices %[ t ! micro-/ructure also v>ies1 ! augite occurr+ sometimes 9 small ophitic plates1 sometimes 9 small r\nd$ granules4 ,! *ief second>y *ange 9 ! body ( ! rock is %[n by ! augite1 :i* is se5 9 v>i\s /ages ( conv]sion to gre5i% fibr\s hornbl5de4 ,"s r\nd pat*es seem also to consi/ ma9ly ( ! latt] m9]al1 & are probably pseudomorphs aft] oliv9e4 ,"h ! little fibres are confus$ly matt$ toge!r1 )\t ! p>allelism prop] to uralite d]iv$ f augite4 ,no fre% oliv9e has be5 obs]v$4 ,! felsp> & magnetite ( ! basalts %[ little or no sign ( metamorphic processes1 unless a r unusual degree ( cle>ness 9 ! felsp> cry/als is to be reg>d$ 9 t light4 ,! cont5ts ( ! metamorphos$ amygdales are n always ! same4 ,epidote is usually pres5t 9 "s abundance1 & 9 well-%ap$ cry/als4 ,x has a pale citron t9t 9 ! slices1 ) m>k$ pleo*roism2 b a giv5 cry/al is n always uni=m 9 its optical *>act]s4 ,frequ5tly ! int]ior is pale1 & has a q l[ birefr+5ce4 ,?is is probably to be reg>d$ z an int]gr[? ( zoisite 9 ! epidote1 & !re are a few di/9ct cry/als ( zoisite se5 9 "s places4 ,9 ! slide :i* be/ exhibits ^! features #ffac ! cry/als ( epidote are 9 "p enwrapp$ & enclos$ by :at are d\btless zeolitic m9]als4 ,at lea/ two ( ^! are to be di/+ui%$4 ,"o1 v ne>ly isotropic1 & ) a pale-br[ni% t9t1 is probably analcime4 ,associat$ ) ?is is a col\rless m9]al ) p>tial radiate arrangem5t & ) tw9 lamellation2 ! birefr+5ce is some:at high] ?an t ( qu>tz1 & ! -axis ( optic ela/icity makes a small angle ) ! tw9-l9e4 ,^! *>act]s agree ) ^? ( epi/ilbite4 ,9 o!r p>ts ( ! same l>ge amygdale1 ! epidote cry/als are emb$d$ 9 :at seems to be a felsp>4 ,?is latt] m9]al is r obscure1 & tw9-lamellation is r>ely to be detect$2 b x seems highly probable t felsp> has "h be5 develop$ by metamorphic ag5cy at ! exp5se ( zeolites :i* once occupi$ ! amygdale4 ,i h obs]v$ und\bt$ examples ( ?is 9 metamorphos$ basalts f o!r p>ts ( ,skye1 e4g4 f ,creagan ,dubha1 ne> ! granophyre mass ( ,be9n ,de>g4#cif ,! felsp> occurs !re 9 ! same fa%ion1 & 9 ! same relation to epidote #bgjj1 #bgja4 ,9 ! specim5s n[ describ$ ! *ief m9]als 9 ! metamorphos$ amygdales are ^? already nam$3 o!rs occur m sp>+ly1 associat$ ) !m4 ,9 "s cases !re is a grass-gre51 /rongly pleo*roic1 act9olitic hornbl5de1 accompani$ by a little iron pyrites #ffae4 ,footnote #cif3 ,comp>e ,trans4 ,roy4 ,soc4 ,ed94 vol4 xxxv4 p4 #aff4 ,epidote & v>i\s hornbl5dic & augitic m9]als are *>act]i/ic products 9 ! metamorphism ( amygdaloidal basalts 9 o!r regions3 felsp> ) ?is mode ( occurr5ce ,i h n se5 except 9 ,skye1 :]e x seems to connect itself naturally ) ! abundance ( zeolites 9 ! amygdales ( ! non-metamorphos$ lavas4 ,x is to be obs]v$ t 9 ^! basalts f ,lo* ,scavaig ! alt]ation is %[n especially 9 ! amygdales1 ! body ( ! rock n be+ greatly affect$3 ?is indicates a n v advanc$ /age ( metamorphism4 ,! production ( uralitic hornbl5de1 r ?an br[n mica1 f ! augite & its decomposition-products1 seems to be *>act]i/ic ( ! metamorphism ( basaltic z di/+ui%$ f &esitic rocks1 & is well illu/rat$ by a comp>ison ( ! two sets ( lavas ne> ! ,%ap granite4#cig ,footnote #cig3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlix4 7#ahic7 p4 #cfa4 ,mr4 ,h>k]1 :o is at pres5t engag$ 9 mapp+ ! c5tral region ( ,skye1 has _h occasion to g ov] a numb] ( ! localities 7,creagan ,dubha1 etc47 orig9ally cit$ by me1 &1 :ile corroborat+ my g5]al conclusions reg>d+ !m1 has be5 able to obta9 mu* fre% evid5ce reg>d+ ! nature & ext5t ( ! metamorphism :i* ! b$d$ basalts h und]gone4 ,! results ( 8 inve/igations w be publi%$ :5 ! ,geological ,survey ( ,skye is fur!r advanc$4 7#c7 ,relation ( ! ,granophyre to ! ,gabbros4--,t ! granophyres invade ! gabbros has be5 incid5tally illu/rat$ 9 ! =ego+ pages4 ,b z ! mutual relations ( ! two rocks 9 ! isl& ( ,skye h be5 ! subject ( frequ5t ref]5ce 9 previ\s writ+s ( geologi/s1 x is desirable to adduce "s detail$ evid5ce f a region :i* has be5 reg>d$ z ! typical "o = ?is feature 9 ! geological /ructure ( ! ,inn] ,hebrides4 ,no geological b\nd>y is m easily trac$ ?an t betwe5 ! pale r$di% granophyre & ! d>k gabbro4 ,x c be foll[$ ) ! eye up a :ole m\nta9 side1 & c be exam9$ s closely t aga9 & aga9 ! obs]v] c walk or climb = "s di/ance ) "o foot on ea* rock4 ,t !re %\ld ev] h be5 any d\bt ab\t ! relations ( ! two eruptive masses is possibly explicable by ! v facility ) :i* _! junction c be obs]v$4 ,_! contra/s ( =m & col\r make _! b\nd>y ov] crag & ridge s cle> t geologi/s d n seem to h tak5 ! tr\ble to foll[ x out 9 detail4 ,& z ! pale rock und\bt$ly (t5 und]lies ! d>k1 !y h assum$ ?is infraposition to m>k its e>li] appe>ance4 ,i w only cite "o "p ( ! junction l9e1 :i* is easily accessible1 = x lies 9 ,gl5 ,sliga*an imm$iately to ! s\? ( ! m\? ( ,h>ta ,corry4 ,! r\nd$ em95ce ( ,meall ,de>g1 :i* rises to ! s\? ( ! two ,black ,lo*s1 belongs to ! granophyre1 :ile ! rugg$ gr\nd to ! we/ ( x lies 9 ! gabbro4 ,! actual contact betwe5 ! two rocks c be foll[$ f ! side ( ,h>ta ,corry ov] ! ridge & d[n into ,/ra? na ,crei!a*1 :5ce x sweeps nor?w>d betwe5 ! r$ cone ( ,ruadh ,/ac & ! black rugg$ declivities ( ,g>bh ,be9n4 ,!re is no m s+ul> sc5e 9 ,skye ?an ! lonely tract on ! s\? side ( ,meall ,de>g4 ,! gr\nd = "s way is ne>ly level1 & /rewn ) r$ %+le f ! decompos+ granophyre und]nea?4 ,x rem9ds "o ( "s p>ts ( ! des]t ,bad l&s ( ,we/]n ,am]ica4 ,grim d>k crags ( gabbro1 ) ve9s f ! granophyre1 rise along its we/]n bord]1 beyond :i* t[] ! black precipices ( ! ,cuill9s1 :ile ! flam+ r$di%-yell[ cones ( ,gl5 ,sliga*an /& out aga9/ ! nor!rn sky4 ,hav+ rec5tly describ$ 9 "s detail ! relations ( ! boss ( granophyre at ?is int]e/+ locality1 ,i w only "h (f] a brief summ>y ( ! *ief features4#cih ,! granophyre ( ,meall ,de>g =ms a m>g9al portion ( ! great mass ( ! ,r$ ,hills4 ,x has brok5 across ! b&$ gabbros1 & also cuts an isolat$ boss ( agglom]ate 9 ! ridge ( ,druim an ,eidhne4 ,its l9e ( junction is ne>ly v]tical1 b along "p ( its c\rse ! wall ( gabbro rises high] ?an t ( ! m decomposable granophyre4 ,h5ce ! orig9 ( ! black crags t cr[n ! r$ slopes ( granophyre debris4 ,se5 f a di/ance ! basic rock seems to re/ z a great b$ ^u ! acid mass4 ,footnote #cih3 ,see ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid7 p4 #bab4 ,! y\ng] date & intrusive nature ( ! granophyre are well %[n by ! *ange 9 ! texture ( ! mass z x approa*es ! rocks aga9/ :i* x has cool$4 ,! ord9>y granophyric *>act]s rapidly pass into a f9e-gra9$ felsitic texture1 & ?is *ange is accompani$ ) ! developm5t ( a rem>kably well-def9$ fl[-/ructure & ( r[s ( sph]ulites :i* run p>allel to ! b\nd>y wall4 ,9 a rav9e on ! we/ side ( ,meall ,de>g1 ! l9es ( fl[-/ructure & r[s ( l>ge sph]ulites are se5 to be arrang$ v]tically aga9/ ! face ( gabbro4 ,fur!r pro( ( ! lat] date ( ! protrusion ( ! granophyre is suppli$ by abundant felsitic dykes & ve9s :i* trav]se ! gabbro1 & "s ( :i* c be se5 to proce$ f ! ma9 body ( granophyre4 ,^! intrusions w be describ$ 9 ! next *apt]1 9 connection ) ! dykes & ve9s ( ! acid rocks4 ,additional evid5ce z to ! po/]iority ( ! granophyre to ! gabbro has rec5tly be5 obta9$ by ,mr4 ,h>k] f a /udy ( ! int]nal /ructure & composition ( ! masses ( ^! rocks :i* h be5 intrud$ into ! agglom]ate above ,lo* ,kil*ri/ 9 ,/ra?4 ,he has f\nd t ! granophyre has !re caught up f "s subt]ranean dep? portions ( gabbro1 & has p>tially dissolv$ !m1 !reby und]go+ a modification ( its own composition4 ,! gabbro-debris1 he rem>ks1 has be5 = ! mo/ "p completely dis9tegrat$ by ! cau/ic or solv5t action ( ! acid magma on "s ( its m9]als4 ,^? con/itu5ts :i* resi/$ su* action h be5 set free & n[ figure z x5ocry/s =eign cry/als1 ei!r intact or m or less p]fectly trans=m$ into o!r sub/ances4 ,at ! same "t ! mat]ial absorb$ has modifi$ ! composition ( ! magma1 9 ! g5]al s5se ( r5d]+ x less acid4 ,mr4 ,h>k] has trac$ ! fate ( ea* ( ! m9]als ( ! gabbro 9 ! process ( solution & isolation 9 ! acid magma1 :i*1 :]e ?is process has be5 mo/ develop$1 is believ$ by him to h tak5 up =eign mat]ial am\nt+ to fully "o-f\r? ( its own bulk1 d]iv$ n f ! rocks imm$iately ar\nd1 b f a gabbro probably at a consid]able dep? b5ea?4#cii ,footnote #cii3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 lii4 7#ahif7 p4 #cbj4 ,illu/ration3 ,fig4 #cej4--;,gr\nd-plan ( basic dyke 9 ,cambrian ,lime/ones truncat$ by granophyre :i* encloses l>ge blocks ( ! dyke1 ,torr91 ,skye4 7#d7 ,relation ( ! ,granophyre to ! ,basic ,dykes & ,ve9s4--,ref]5ce has already be5 made to ! fact t ! sy5ite bosses ( ,skye cut (f mo/ ( ! basalt-dykes1 b are !mselves trav]s$ by a few o!rs4#djj ,! locality t furni%$ me ) ! evid5ce on :i* ?is /atem5t 0 orig9ally made ne>ly =ty ye>s ago af=ds 9 small compass a cle>] pres5tation ( ! facts ?an ,i h else:]e met )4 ,! sections describ$ by me are visible at ! ea/]n end ( ! boss ( ,be9n an ,dubhai*1 ,/ra?2 b simil> & ev5 bett] examples may be cit$ f ! :ole nor!rn & s\!rn m>g9s ( t eruptive mass4 ,on ! nor? side an extraord9>y numb] ( dykes may be trac$ 9 ! ,cambrian lime/one f ! %ores ( ,lo* ,slap9 ea/w>ds4 ,!y h a g5]al nor?-we/]ly tr5d1 b "o aft] ano!r1 z ,i h already rem>k$1 is abruptly cut (f by ! granophyre4 ,z an example ( ! way 9 :i* ?is truncation takes place1 ,i may site a s+le illu/ration f ! nor!rn m>g9 ( ! eruptive mass1 ne> ,torr94 ,x might p]haps be cont5d$ t ! num]\s dykes :i* trav]se ! lime/one & /op %ort at ! edge ( ! acid rock1 are n necess>ily old] ?an ! granophyre1 b may actually be y\ng]1 _! sudd5 t]m9ation at ! edge ( ! acid boss be+ due to _! inability to trav]se t rock4 ,t ?is explanation is unt5able is readily prov$ by su* sections z t giv5 9 ,fig4 #cej1 :]e a basic dyke 7b7 #i or #aj feet broad runn+ ?r\gh ! ,cambrian ,lime/one 7a a7 is abruptly cut (f by ! edge ( ! great granophyre boss4 ,n only is ! dyke %>ply truncat$1 b num]\s pieces ( x1 f an in* to m ?an a foot 9 l5g?1 are enclos$ 9 ! granophyre4 ,! latt] is well expos$ along ! %ore ( ,lo* ,slap9 9 an almo/ cont9u\s section ( ne>ly a mile 9 l5g?4 ,! contra/ !re=e betwe5 ! developm5t ( dykes )9 & beyond its area _c b arre/ ! att5tion ( ! obs]v]4 ,?\gh ,i 0 on ! outlook = dykes 9 ! granophyre1 ,i f\nd only "o4 ,yet imm$iately beyond ! eruptive boss !y at once appe> on ei!r side up to its v edge1 :]e !y sudd5ly cease4 ,! conclusion _c be resi/$ t ! protrusion ( ! acid rock took place aft] mo/ ( ! dykes ( ! di/rict _h be5 =m$1 b be=e ! emission ( ! v late/ dykes1 :i* pursue a nor?-we/ c\rse across ! boss 7,fig4 #cdh74 ,footnote #djj3 ,ante1 p4 #agc1 & ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xiv4 7#aheg7 p4 #af4 ,"s sections on ! s\!rn m>g9 ( ,be9n an ,dubhai* complete ! demon/ration t su* has be5 ! ord] ( appe>ance ( ! rocks4 ,ne> ! head ( ! ,allt ,l? ,slighe 7or ,half-way ,burn71 :]e ! granite has pu%$ a long tongue into ! lime/one1 a nor?-we/ basalt-dyke is abruptly cut (f by ! ma9 body ( ! boss & by ! protrud$ ve9 7,fig4 #cea74 ,besides ?is truncation1 ! acid rock s5ds out /r+s & ?reads ( its own sub/ance into & across ! dyke1 ^! inject$ portions be+ z usual ( an exce$+ly f9e felsitic texture4 ,illu/ration3 ,fig4 #cea4--,section on s\? side ( ,be9n an ,dubhai*1 ,skye1 %[+ ! truncation ( a basalt-dyke 7b71 9 ,cambrian ,lime/one 7a71 by ! granite 7c7 ( ,be9n an ,dubhai*1 ,skye4 ,simil> evid5ce may be ga!r$ f ! area ( ! great granophyre cones fur!r nor?4 ,! pr(usion ( basalt-dykes 9 ! surr\nd+ rocks /ops %ort at ! m>g9 ( t area4 ,! comp>atively few dykes :i* cross ! b\nd>y pursue a g5]al nor?-we/ c\rse ?r\gh ! granophyre1 &1 z already rem>k$1 f _! d>k col\r1 great] durability & /raightness ( direction1 /& out z prom95t ribs on ! flanks ( ! pale cones :i* !y trav]se4 ,,*apt] ,,xlvii ,,! ,,acid ,,bosses ,,( ,,mull1 ,,small ,,isles1 ,,/4 ,,kilda1 ,,arran ,,& ,,! ,,nor?-,,ea/ ,,( ,,irel& ii4 ,,! ,,acid ,,bosses ,,( ,,mull ,?\gh ( comp>atively small ext5t1 ! granophyre bosses ( ! isl& ( ,mull af=d to ! geologi/ a l>ge am\nt ( in/ruction 9 reg>d to ! relations ( ! diff]5t memb]s ( ! volcanic s]ies to ea* o!r4 ,especially important is ! evid5ce :i* !y conta9 ( ! connection betwe5 ! acid & basic gr\ps ( rocks4 ,!y h be5 laid b>e 9 _m natural sections1 "s ( :i*1 =m+ entire hillsides1 are among ! mo/ a/oni%+ 9 ! :ole wond]ful s]ies :i*1 dissect$ by d5udation1 reveal to u ! /ructure ( ^! volcanic regions4 ,!y lie 9 two *ief areas4 ,"o ( ^! ext5ds along ! nor!rn flanks ( ! m\nta9\s tract f ! we/]n side ( ,be9n ,fhada across ,lo* ,ba' to ! we/ side ( ,gl5 ,=sa4 ,! o!r occupies = ov] ?ree miles ! bottom ( ,gl5 ,m1 ! deep valley :i*1 skirt+ ! s\!rn side ( ! *ief gr\p ( hills1 connects ! ea/ side ( ! isl& by road ) ! head ( ! great we/]n inlet ( ,lo* ,scrida94 ,!re are o!r m9or areas4 ,"o ( ^! ext5ds = ab\t a mile along ! declivities to ! s\? ( ,sal51 across ! valley ( ! ,allt na ,se>mo92 ano!r occurs at ,sal52 a ?ird runs along ! %ore at ,craignure4 ,9 ! int]ior also1 _m isolat$ areas ( simil> rocks1 besides ?\s&s ( ve9s1 occur 9 ! c5tral gr\p ( hills & valleys :i* =m ! bas9s ( ! ,gl5cannel & ,=sa riv]s 7,map ,,vi474 ,! *ief nor!rn boss1 :i* = ! sake ( conv5i5ce ( ref]5ce may be call$ t ( ,lo* ,ba'1 has a l5g? ( ne>ly six miles1 ) a bread? v>y+ f a qu>t] ( a mile to ab\t a mile & a qu>t]4 ,x desc5ds to )9 #ej feet ( ! sea-level1 & is expos$ along ! cre/ ( ,be9n ,fhada at a height ( m ?an #ahjj feet4 ,x *iefly consi/s ( a grey cry/all9e rock :i* might readily be id5tifi$ z a granite1 b :i* :5 exam9$ microscopically is f\nd to possess ! granophyric /ructure4 ,) ?is di/9ctly granul>-cry/all9e rock are associat$ v>i\s porphyritic & felsitic masses1 :i* pass into x1 & are m specially obs]vable along its bord]4 ,an exce$+ly compact black qu>tz-felsite or rhyolite =ms its s\!rn b\nd>y1 runs z a broad dyke-l ridge f ! head ( ! ,sc>risdale ,wat] nor?-ea/w>d across ,lo* ,ba' 7,fig4 #ceb71 & spreads out ea/w>d into a mass m ?an a mile broad on ! heights above ,kilbeg 9 ,gl5 ,=sa4 ,! %>p l9e ( dem>cation ( ?is felsite1 & its mass & ext5t1 po9t to a diff]5t p]iod ( extravasation4 ,illu/ration3 ,fig4 #ceb4--,view ( ! hills on ! s\? side ( ! head ( ,lo* na ,keal1 %[+ ! junction ( ! granophyre & ! b$d$ basalts4 ,"o bird1 ! b$d$ basalts ( ! ,gribon plateau2 two birds1 ! b$d$ dol]ites & basalts ( ,be9n a' ,*raig adh]+ to ! nor!rn slope & capp+ ! hill2 ?ree birds1 summit ( ,b5 ,m1 ) ,a',*io* to ! left & ! top ( ,be9n ,fhada appe>+ 9 ! middle di/ance betwe5 !m2 f\r birds1 ! granophyre slopes ( ,be9n a' ,*raig ) ! great dyke-l mass ( felsite on ! left4 ,! geologi/1 :o approa*es ?is di/rict f ! nor?-ea/1 has 8 att5tion arre/$1 ev5 at a di/ance ( sev]al miles1 by ! contra/ betwe5 ! out] & inn] p>ts ( ! hills t lie to ! s\?-we/ ( ,lo* ,ba'4 ,he c readily trace f af> ! d>k b$d$ basic rocks ris+ t]race above t]race1 f ! %ores ( ,lo* na ,keal1 to =m ! seaw>d faces ( ! hills along ! s\!rn side ( t fjord4 ,b he obs]ves t imm$iately beh9d ^! t]races ! mass ( ! ris+ gr\nd obvi\sly consi/s ( "s amorph\s rock1 :i* wea!rs into :ite debris4 ,no?+ c be %>p] ?an ! contra/ ( col\r & =m betwe5 ! two p>ts ( ! hills4 ,! b$d$ plateau-rocks lie z a k9d ( wall or v5e] aga9/ a /eep face ( ! /ructureless int]ior 7,fig4 #ceb74 ,se5 f ! o!r or hilly side1 ! contra/ is p]haps ev5 m /rik+4 ,b ! a/oni%m5t ) :i* x is beheld at a di/ance becomes int5sifi$ :5 "o climbs ! slopes1 & f9ds t ! %eets ( dol]ite & basalt 7:i* f "s po9ts ( view look q level1 yet dip t[>ds ! nor?-ea/ at a g5tle angle7 are imm$iately beh9d ! declivity abruptly truncat$ by a mass ( granophyre4 ,( all ! junction-l9es betwe5 ! acid bosses & ! lavas ( ! plateaux1 ^? expos$ on ^! ,mull hillsides are c]ta9ly ! mo/ extraord9>y4 ,s little di/urb$ are ! lavas1 t "o's fir/ impulse is to se>* = pebbles ( ! granophyre betwe5 ! basalts1 = x seems incr$ible t ! inn] rock %\ld be any?+ b a c5tral core ( old] eruptive mat]ial1 aga9/ & r\nd :i* ! y\ng] basic rocks h fl[$4 ,b1 ?\gh ! granophyre is s decompos+ & cov]s its slopes ) su* screes ( debris1 t _h ! basalts be5 p\r$ r\nd x1 !y mu/ infallibly h _h "s ( its fragm5ts wa%$ d[n betwe5 _! successive fl[s1 n a s+le pebble ( x is !re to be f\nd4 ,?is might n be consid]$ decisive evid5ce1 b x is ext5d$ & confirm$ by ! fact t ! acid rock gives (f ve9s :i* ramify ?r\gh ! basalts4 ,be=e exam9+ ! actual contact ( ! two rocks1 h[ev]1 ! geologi/ w n fail to obs]ve "h an admirable example ( ! gradual *ange :i* 0 describ$ 9 ! =ego+ *apt] z com+ ov] ! b$d$ basalts ne> ! acid bosses4 ,z he approa*es ! nucleus ( :ite rock1 ! basalts assume ! usual h>d indurat$ "*1 n decay+ into br[n s& z on ! plateaux1 b (t5 /&+ out z massive crags ) v]tical clean-cut jo9t-faces4 ,?is metamorphos$ condition ext5ds 9 "s cases to a consid]able di/ance f ! ma9 body ( acid rock1 especially :]e knobs ( t mat]ial1 protrud+ ?r\gh ! m basic lavas1 %[ t x mu/ ext5d 9 "s mass und]nea?4 ,?us along ! %ore at ,sal9e ! b$d$ basalts succe$ ea* o!r 9 well-def9$ %eets1 "s be+ solid1 massive & non-amygdaloidal1 o!rs q vesicul>1 & recall+ ! black scori=m surfaces ( rec5t ,vesuvian lavas2 yet !y are all m indurat$ ?an 9 ! normal plateau-c\ntry1 & !y break ) a h>d spl9t]y fracture4 ,imm5se numb]s ( dykes cut ^! rocks1 & !y are likewise pi]c$ by occasional felsitic intrusions4 ,if we cross to ! o!r side ( ! isl& & trace ! b$d$ basalts away f ! c5tral masses ( acid rock we meet ) s gradual a dim9ution ( ! induration t no def9ite b\nd>y-l9e = ! metamorphism c be drawn4 ,z we rec$e f ! c5tre ( alt]ation1 ! rocks ins5sibly beg9 to %[ br[n wea!r$ cru/s1 ) sph]oidal exfoliation1 ! reticulations ( epidote & calcite become mu* less abundant1 ! amygdaloids gradually assume _! normal e>?y "*1 & ev5tually we f9d ourselves on ! famili> types ( ! plateau4 ,?is transition is well se5 along ! %ores ( ,lo* na ,keal4#dja ,footnote #dja3 ,"s ( ! ?ick massive %eets ( basic rock along ! s\? side ( ?is inlet may possibly be alt]$ sills4 ,^! pro(s ( ! alt]ation ( ! plateau-basalts are accompani$ 9 ,mull z 9 ,skye by fur!r abundant evid5ce t ! acid rocks are ( y\ng] date ?an ! basic4 ,9 p>ticul>1 dykes & ve9s may be trac$ proce$+ f ! =m] & int]sect+ ! latt]4 ,?us1 9 ! b$ ( ! s\? =k ( ! ,sc>risdale /ream1 a sep>ate mass ( granophyre 7:i* "u ! microscope exhibits 9 p]fection ! *>act]i/ic /ructure ( ?is rock7 protrudes ?r\gh ! basalts 9 advance ( ! ma9 mass1 & a little high] up on ! outskirts ( t mass n>r[ ribbons ( ! granophyre run ?r\gh ! basic rocks4 ,! contra/ ( col\r betwe5 ! pale ve9s ( ! intrusive rock & ! d>k t9t ( ! basalts is well %[n 9 ! *annel ( ! wat]4 ,simil> sections may be se5 on ! flanks ( ,be9n ,fhada1 especially 9 ! great corry nor? ( ,b5 ,m1 :]e ! granophyre s5ds a tongue ( f9] gra9 betwe5 ! b$s ( basalt4 ,on ! ea/ side ( ,lo* ,ba' num]\s pro(s ( simil> intrusion may be obs]v$4 ,?us at ! ea/ end ( ,lo* na ,diridh1 :]e ! granophyre has be5 intrud$ into ! basalts1 h&-specim5s may be obta9$ %[+ ! two rocks weld$ toge!r4 ,on ! slopes ( ,crua* ,trr an ,lo*a91 :]e ! granophyre has a felsitic selvage1 ! b$d$ basalts are trav]s$ by ve9s ( ! latt] mat]ial 7,fig4 #cec74 ,a little fur!r ea/1 at ! head ( ! ,allt na ,se>mo91 ! b$d$ basalts1 "s ( :i* are sep>at$ by slaggy scoriace\s surfaces1 are int]sect$ by ano!r protrusion f ! compact felsitic porphyry 7,fig4 #ced74djb ,a mile l[] d[n ! same valley a sep>ate mass ( granophyre s5ds out ve9s into ! basalt1 :i* z usual is d>k blui%-grey 9 col\r1 indurat$ & spl9t]y4 ,footnote #djb3 ,?is rock appe>s to ! eye z a black f9ely cry/all9e-granul> felsite4 ,"u ! microscope1 x 0 f\nd by ,dr4 ,hat* to pres5t a m>k$ly granulitic /ructure1 consi/+ ma9ly ( small r\nd$ gra9s ( dirty br[n turbid felsp>1 ) isolat$ granules ( col\rless qu>tz4 ,scatt]$ ?r\gh ! rock1 or accumulat$ 9 pat*es1 are small sph]ical or drop-l granules ( a bright gre5 augite 7coccolite74 ,illu/ration3 ,fig4 #cec4--,section on s\? side ( ,crua* ,trr an ,lo*a91 ,mull4 a1 b$d$ basalts & dol]ites2 b1 granophyre2 c1 m>g9al f9]-gra9$ b&2 d d1 ve9s f ! granophyre trav]s+ ! basic rocks4 ,illu/ration3 ,fig4 #ced4--,section at head ( ,allt na ,se>mo91 ,mull4 a1 basalts & dol]ites1 ) slaggy upp] surfaces2 b1 felsite4 ,z ! po/]iority ( ! ,mull granophyre & felsites to ! basalts is ?us prov$1 ! fur!r "q rema9s z to _! mann] ( intrusion4 ,"h & !re1 especially on ! s\?-ea/]n side1 betwe5 ! head ( ! ,sc>risdale riv] & ,lo* ,ba'1 ! l9e ( junction betwe5 ! two rocks is ne>ly v]tical1 b a body ( black felsite int]v5es z a huge wall betwe5 ! ord9>y granophyre & ! basalt4 ,on ,be9n ,fhada & ,be9n a' ,*raig ! l9e ( sep>ation1 z ,i h above rem>k$1 is incl9$ outw>ds1 & plunges "u ! basalts at an angle ( #cj to #dj4 ,! t]rac$ basalts & dol]ites are n s5sibly di/urb$1 b end (f abruptly aga9/ ! /eep face ( intrusive rock4 ,we might suppose t 9 ?is case ! y\ng] rock _h m]ely c>ri$ upw>d ! cont9uation ( ! b$s t are truncat$ by x1 z if an orifice _h be5 pun*$ out = its asc5t4 ,b on ! top ( ! ridge ( ,be9n a' ,*raig we f9d t ! outli]s :i* !re rema9 are n portions ( ! l[] basalts1 b ( ! upp] pale gr\p ( ,b5 ,m4 ,! same rocks are prolong$ on ! o!r side ( ! ,sc>risdale ,gl51 sweep ov] ! summit ( ,be9n ,fhada1 & run on cont9u\sly into ! cre/ ( ,a',*io* & ! upp] "p ( ,b5 ,m4 ,! granophyre has usurp$ ! place ( ! l[] dol]ites & basalts1 b has left ! m felspa?ic lavas ( ! pale gr\p 9 _! prop] position4 ,& to make ?is rem>kable /ructure /ill m cle>1 sections may be se5 on ! s\!rn flanks ( ,be9n ,fhada1 :]e ! upp] surface ( ! granophyre comes d[n obliquely across ! edges ( ! lavas1 & all[s ! junction ( ! basalts & ! pale gr\p to be se5 above x 7,fig4 #cee74 ,z 9 ! case ( ,be9n an ,dubhai*1 x is z if ! granophyre _h eat5 its way upw>d & dissolv$ ! rocks :i* x has replac$4 ,illu/ration3 ,fig4 #cee4--,section on s\? side ( ,be9n ,fhada1 ,mull4 a1 b$d$ basalts & dol]ites2 b1 pale gr\p ( ,b5 ,m2 c1 granophyre4 ,! usual k9d ( contact-metamorphism has be5 produc$ ar\nd ?is intrusive boss4 ,x is mo/ m>k$ 9 ! outli]s t cap ,be9n a' ,*raig & on ! two ridges to ! s\?-we/1 :]e x is se5 to consi/ 9 a high degree ( induration1 ! production ( a %att]y1 irregul>ly-jo9t$ /ructure1 & ! effacem5t ( ! obvi\s b$d+ :i* *>act]izes ! unalt]$ rocks4 ,! position ( ?is eruptive mass1 q a mile broad1 break+ ?r\gh1 )\t viol5tly tilt+1 m ?an #ahjj feet ( ! b$d$ basalts1 & !n /opp+ %ort ab\t ! base ( ! pale gr\p1 pres5ts a curi\s problem to ! /ud5t ( geological physics4 ,x at once rem9ds him ( _m sections among ,palozoic granites :]e an eruptive boss has asc5d$ & tak5 ! place ( an equival5t volume ( ! surr\nd+ rocks1 :i*1 ?\gh m or less metamorphos$1 are n made to dip away f x z f a solid w$ge driv5 upw>ds ?r\gh !m4 ,9 ?is ,mull case1 h[ev]1 !re are "s peculi> features t des]ve consid]ation1 = !y seem to %[ t "h1 z else:]e1 passages = ! uprise ( ! intrusive rock 7 already provid$ by ! pres5ce ( volcanic pipes1 :i*1 ev5 if fill$ up ) fragm5t>y mat]ials1 w\ld no d\bt cont9ue to be po9ts ( weakness4 ,r\nd ! flanks ( ! ,lo* ,ba' boss1 & "h & !re on its surface1 pat*es ( int5sely indurat$ volcanic agglom]ate may be detect$4 ,a little to ! s\? ( ! t>n call$ ,lo* na ,diridh1 ! granophyre is succe$$ by ! black1 fl9ty felsite or rhyolite already ref]r$ to4 ,?is rock 9 "s places exhibits a beautiful fl[-/ructure1 ) l>ge porphyritic felsp>s1 & encloses a great _m fragm5ts ( dol]ite & gabbro1 v>y+ f ! size ( a pea up to blocks sev]al in*es 9 diamet]4 ,ly+ on its surface are deta*$ knolls ( mu* alt]$ dol]ite1 basalt1 & co>se breccia or agglom]ate4 ,on its s\!rn m>g9 "o ( ^! pat*es ( agglom]ate conta9s abundant fragm5ts ( v>i\s felsitic rocks1 among :i* are pieces ( a compact rock ) fl[-/ructure l t f\nd 9 place imm$iately to ! nor?2 also r\nd$ pieces ( qu>tzite1 & ( compact & amygdaloidal basalt wrapp$ up 9 a v h>d matrix :i* seems to consi/ l>gely ( basalt-du/4 ,no b$d+ c be made out 9 ?is rock1 & ! mass looks l "p ( a true neck4 ,fur!r d[n ! slope ! b$d$ basalts appe>4 ,! actual junctions ( ! diff]5t rocks _c be satisfactorily trac$1 b ! /ructure ( ! gr\nd appe>s to me to be z %[n 9 ,fig4 #cef4 ,a pat* ( simil> agglom]ate appe>s a little to ! s\?-we/ ( ! la/ section 9 front ( a cliff ( ! felsite1 & seems to be enclos$ 9 ! latt] rock1 & o!r exposures ( agglom]ate1 und]la9 & int5sely indurat$ by ! felsite1 may be notic$ on ! gr\nd t slopes t[>ds ,lo* ,ba'4 ,illu/ration3 ,fig4 #cef4--,section to s\? ( ,lo* na ,diridh1 ,mull4 a1 basalts2 b1 dol]ite2 c1 volcanic agglom]ate2 d1 black felsite2 e1 granophyre4 ,t ^! agglom]ates d n belong to ! p]iod ( ! eruption ( ! granophyre & felsite1 b to t ( ! b$d$ basalts1 may be inf]r$ f _! int5se induration next ! acid rocks1 & also f ! fact t simil> breccias are actually f\nd "h int]pos$ betwe5 ! b$d$ basalts4 ,?is is well %[n on ! hill above ! ,coille na ,srine1 :]e ! accompany+ section c be se5 7,fig4 #ceg74 ,! broad dyke-l mass ( black fl9ty felsite already ref]r$ to runs z a prom95t rib ov] ! s\!rn end ( ,be9n a' ,*raig into ! head ( ! ,sc>risdale gl5 7see ,fig4 #ceb74 ,x cuts across ! b$d$ basalts1 & imm$iately to ! s\? ( :]e ^! appe>1 a ?9 int]calat$ b$ ( breccia crops out1 ( ! usual dull-gre5 col\r1 ) abundant fragm5ts ( basalt & _m ( yell[ & grey felsite4 ,f ^! v>i\s facts we may1 ,i ?9k1 conclude t along ! /rip ( gr\nd n[ occupi$ by ! ,lo* ,ba' boss ( granophyre & felsite1 !re once /ood a l9e or gr\p ( v5ts1 f :i*1 besides ! usual basalt-debris1 !re 7 eject$ _m pieces ( diff]5t felsitic or rhyolitic rocks1 & t ^! eruptions ( fragm5t>y mat]ial took place dur+ ! accumulation ( ! plateau-basalts4 ,^! volcanic funnels occasion$ a s]ies ( po9ts or a l9e ( weakness ( :i*1 9 a long subsequ5t episode ( ! protract$ volcanic p]iod1 ! acid rocks took advantage1 =c+ !mselves upw>ds !re91 & leav+ only slight traces ( ! v5ts :i* assi/$ _! asc5t4 ,! m+l+ ( acid & basic fragm5ts 9 ! mat]ial eject$ f ^! v5ts is ano!r pro( ( ! exi/5ce ( acid rocks 9 ! volcanic res]voirs be=e ! adv5t ( ! great granophyre intrusions4 ,! evid5ce ?us entirely confirms ! conclusions d$uc$ f ! ,skye area4 ,illu/ration3 ,fig4 #ceg4--,section ( junction ( s\? side ( ,lo* ,ba' granophyre boss1 ) ! b$d$ basalts1 ,mull4 a1 b$d$ basalts2 b b1 basalt-tuff & breccia2 c1 granophyre2 d1 black felsite2 e1 co>se dol]ite dyke1 #cj or #dj feet wide4 ,! second or ,gl5 ,m boss1 in/ead ( ris+ into hilly gr\nd1 is conf9$ to ! bottom ( ! ma9 & tribut>y valleys1 & has only be5 reveal$ by ! ext5sive d5udation to :i* ^! holl[s owe _! orig94 ,x beg9s ne>ly a mile bel[ ,torness & ext5ds up to ,lo* ,airdeglais--a di/ance ( almo/ f\r miles4 ,?\gh s+ul>ly devoid ( topographical feature1 x exhibits ) admirable cle>ness ! relation ( ! granophyres to ! gabbros1 & ?us des]ves an important place among ! tracts ( acid rocks 9 ! ,we/]n ,isl&s4 ,its petrographical *>act]s *ange consid]ably f "o "p ( its body to ano!r4 ,= ! mo/ "p1 x is a true granophyre1 sometimes ) or?oclase1 sometimes ) plagioclase z its pr$om9ant felsp>4 ,at ,i%riff1 z already /at$1 x is spr9kl$ ) long acicul> decay$ cry/als ( hornbl5de2 b at ! wat]%$ ! f]ro-magnesian m9]al is augite4 ,! surr\nd+ rocks are ma9ly ! plateau-basalts1 ) _! sills ( dol]ite & gabbro4 ,illu/ration3 ,fig4 #ceh4--,mass ( d>k gabbro ab\t two feet 9 diamet] trav]s$ by pale ve9s ( granophyre1 ly+ on nor? slope ( ,creag na h-,iolaire1 ,mull4 ,illu/ration3 ,fig4 #cei4--,section at ,creag na h-,iolaire1 ,gl5 ,m1 ,mull1 %[+ basalts & gabbros re/+ on & pi]c$ by granophyre4 a1 mu* indurat$ & alt]$ basalts & dol]ites2 b b1 gabbro2 c1 granophyre2 d d1 basalt dykes4 ,?is /rip ( granophyre s5ds abundant apophyses f its mass into ! d>k basic rocks ar\nd x4 ,"s ( ! be/ sections to %[ ! nature ( ^! (f%oots are to be f\nd on ! /eep hillslope :i* m\nts f ! wat]%$ 9 ,gl5 ,m s\?w>d into ! ,creag na h-,iolaire 7,eagle's ,crag71 & !nce up into ! great gabbro ridge ( ,b5 ,buy4 ,f ! ma9 body ( granophyre a multitude ( ve9s asc5ds ?r\gh ! basalts & gabbros f two feet or m 9 bread? d[n to m]e filam5ts 7,fig4 #ceh74 ,ev5 at a height ( #cjj feet up ! hill "s ( ^! ve9s are /ill ?ree in*es broad1 & pres5t ! usual granophyric /ructure1 ?\gh r f9] 9 gra9 ?an ! g5]al mass ( ! boss1 & sometimes assum+ a compact felsitic & sph]ulitic texture at ! imm$iate contact ) ! surr\nd+ rock4 ,"o ( ! mo/ /rik+ pro(s ( ! po/]iority ( ^! ve9s is furni%$ by ! p]fect fl[-/ructure !y n infrequ5tly exhibit along _! m>g9s1 _! long felsp> cry/als be+ arrang$ p>allel to ! walls 9 l9es t foll[ ! s9uosities ( ! b\nd>y betwe5 ! two rocks4 ,pat*es ( gabbro & ( ! indurat$ basalts may be se5 ly+ on ! granophyre1 f :i* ve9s & /r+s ramify ?r\gh !m 7,fig4 #cei74 ,simil> ve9s c be trac$ upw>d into ! ma9 body ( co>se gabbro1 =m+ ! ridge ( ,b5 ,buy4 ,"s ( !m are ( ! usual granul> granophyric texture1 o!rs are dull & f9e-gra9$ 7clay/ones ( ! old] au?ors74 ,h5ce x is evid5t t ! granophyres ( ,mull h be5 protrud$ n only aft] ! accumulation ( ! plateau-basalts1 b aft] ^! 7 trav]s$ by ! %eets & ve9s ( gabbro4 ,! am\nt ( acid rock inject$ into ^! old] rocks ov] ! m\nta9\s "p ( ! isl& is enorm\s2 b ,i res]ve fur!r ref]5ce to x = ! section on acid ,dykes & ,ve9s1 = ^! are ! =ms 9 :i* x *iefly occurs 9 t region4 ,x %\ld be add$1 t 9 ! localities "h ref]r$ to basalt-ve9s & dykes are g5]ally abundant1 cutt+ ?r\gh all ! o!r rocks 7,fig4 #cei74 ,s num]\s are !y t ! geologi/ ceases to take note ( !m :5 8 ?\ghts are engag$ ^u ! problems pres5t$ by ! masses ?r\gh :i* !y rise4 iii4 ,,! ,,acid ,,bosses ,,( ,,small ,,isles ,9 ! isl& ( ,eigg ?ree small bosses or %eets ( acid rock occur4 ,t at ! nor!rn end rises ?r\gh ! ,jurassic s$im5t>y rocks1 & =ms a bold cliff f #aej to #bjj feet high4 ,x is a light grey granophyric porphyry1 ) r\nd$ blebs ( qu>tz 9 a micropegmatic base ( qu>tz & felsp>4 ,! o!r two masses1 ( small] size1 cut ?r\gh ! b$d$ basalts#djc 7,map ,,vi474 ,footnote #djc3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxvii4 7#ahga7 p4 #bid4 ,9 ! opposite isl& ( ,rum1 ! acid protrusions play a mu* m important "p4 ,on ! ea/ side ( ! hills1 !y occur 9 %eets at ! base ( ! gabbros2 on ! we/ side1 !y =m a l>ge tract ( hilly gr\nd1 :i*1 /ret*+ along ! coa/-l9e = ab\t ?ree & a half miles f ! headl& ( ,a' ,bhrideana* to ,h>ris1 =ms !re a range ( %att]$ sea-cliffs1 t t[] = #ajjj feet above ! ,atlantic break]s t beat ab\t _! base4 ,! area ext5ds inl& to ! slopes on ! we/ side ( ,lo* ,sga?aig1 a di/ance ( ab\t ?ree & a half miles1 desc5d+ 9 a range ( precipices along its nor!rn front1 & rea*+ 9 its culm9at+ summit1 ,orval1 a height ( #ahfh feet above ! sea4 ,! rocks ( :i* ?is triangul> area consi/s resemble ^? ( ! ,mull bosses4 ,!y are *iefly qu>tz-porphyries1 becom+ felsitic 9 texture t[>ds _! contact ) adjac5t rocks4 ,9 "s places1 z 0 notic$ by ,maccullo* on ! sea-cliffs1#djd !y h a rudely b$d$ /ructure4 ,?us on ! nor?-we/ front ( ,orval1 ?is /ructure is %[n by p>allel planes t dip outw>ds or nor?-we/ at #cj to #dj1 & :i* are made /ill m di/9ct by an occasional intrusive dyke or %eet ( basalt betwe5 _! surfaces4 ,i h already allud$ to indications ( an int]nal arrangem5t 9 ! granitoid bosses ( ,skye 7p4 #cha74 ,footnote #djd3 ,we/]n ,isl&s1 vol4 i4 p4 #dhg4 ,illu/ration3 ,fig4 #cfj4--,section on nor? side ( ,orval1 ,rum4 a1 ,torridon s&/ones2 b1 b$d$ basalts ( ,fionn ,*ro2 c1 dol]ite2 d1 qu>tz-porphyry4 ,illu/ration3 ,fig4 #cfa4--;,junction ( ,qu>tz-,porphyry 7,microgranite7 & ,basic ,rocks1 s\?-ea/ side ( ,orval1 ,rum4 a1 basalts & dol]ites2 b1 dol]ite & gabbro ve9s2 c1 qu>tz-porphyry cutt+ a & b4 ,z 9 ! o!r isl&s1 ! granophyres1 porphyries & felsites ( ,rum h be5 intrud$ at ! base ( ! volcanic s]ies4 ,ov] mu*1 if n all1 ( _! area !y lie directly on ! r$ ,torridon s&/one4 ,t ! b$d$ basalts once cov]$ !m is indicat$ by ! position ( ! ?ree outli]s ( ! basalt-plateau already notic$4 ,b a f\r? outli] /ill lies ^u ! porphyry ( ,orval z a cake t dips g5tly nor?w>d4 ,x consi/s ( a b$d$1 d>k1 f9ely-cry/all9e1 ophitic dol]ite1 porphyritic 9 places1 ) a rudely prismatic or column> /ructure 7,fig4 #cfj74 ,x has und]gone contact-metamorphism1 & tongues f ! und]ly+ rock project up into x4 ,on ! s\?-ea/]n side ( ! same hill1 /ill m /rik+ evid5ce is pres5t$ ( ! po/]iority ( ! acid to ! basic rocks4 ,! porphyry %[s "h ! same t5d5cy to assume a b$d$ /ructure1 ! p>allel b$s aga9 dipp+ outw>d or s\?-ea/ at #dj4 ,!y plunge "u ! body ( gabbro1 dol]ite & o!r intrusive masses :i* f ?is po9t /ret* ea/w>d into ! great cones ( ,allival & its neighb\rs4 ,! rock at ! junction is a f9e microgranite ) traces ( micropegmatite4 ,x is compos$ ( a holocry/all9e base ( qu>tz & or?oclase1 ) porphyritic cry/als ( microcl9e1 blebs ( qu>tz & scatt]$ granules ( augite4 ,! rocks t re/ imm$iately next x are basalt & dol]ite1 into :i* x has s5t an intricate network ( ve9s 7,fig4 #cfa74dje ,x has also pu%$ long tongues d[n ! slope into !m1 :i* may be se5 trav]s+ ! dol]ite & gabbro ve9s t cut ! basalts4 ,! basic rocks next ! porphyry h be5 int5sely alt]$4 ,!y seem 9 places z if !y h be5 %att]$ by "s explosive =ce1 & _h !n be5 invad$ by ! mass t ru%$ into all ! r5ts ?us caus$4 ,?is rem>kable /ructure is /ill bett] display$ on ,/4 ,kilda1 & is m fully describ$ 9 ! foll[+ acc\nt ( ! geology ( t isl&4 ,footnote #dje3 ,9 a ?9 slice cut f a specim5 %[+ ! junction1 !re is a m9ute ve9 ( ! porphyry p5etrat+ ! basalt :i* is mu* alt]$1 :ile ! porphyry becomes mu* f9] 9 gra9 ?an at a di/ance f ! contact4 iv4 ,,! ,,rocks ,,( ,,/4 ,,kilda ,brief allusions to ,/4 ,kilda & its rocks h already be5 made 7pp4 #agc1 #ceh74 ,we may n[ ent] m fully ^u ! consid]ation ( its geological /ructure & hi/ory4 ,:5 ! wea!r is cle> !re may be se5 f ! we/]n headl&s ( ! ,out] ,hebrides a small blue cone ris+ above ! ,atlantic horizon at a di/ance ( ab\t #fj miles4 ,z ! voyag] approa*es ?is di/ant l& x gradually %apes itself into a gr\p ( islets ( :i* ,/4 ,kilda1 ! l>ge/ & only inhabit$1 has an extreme l5g? ( ab\t f\r miles1 a bread? ( less ?an two miles1 & a height ( #abfb feet above ! sea4 ,f\r miles to ! nor?-ea/ ,borr]a1 ab\t "o squ>e mile 9 ext5t1 rises ) precipit\s sides to a height ( #ajjj feet4 ,(f ! nor?-we/]n promontory ( ,/4 ,kilda ! huge rock ( ,soay1 half a squ>e mile 9 area1 t[]s f #fjj to #hjj feet above ! waves4 ,borr]a has two att5dant rocks--,/ack ,li & ,/ack an ,arm9--huge pyramidal masses sev]al hundr$ feet high1 & ! home ( ?\s&s ( gannets4 ,/4 ,kilda possesses two less impos+ islets betwe5 its nor?-we/]n headl& & ,soay1 & a ?ird to ! s\?-ea/ kn[n z ,lev5i%4 ,! sc5]y ( ?is picturesque gr\p af=ds a good indication ( its geological /ructure4 ,x displays two di/9ct types ( topographical =m4 ,9 ,borr]a ! m>vell\s comb9ation ( spiry ridges1 deep gullies & clefts1 not*$ cre/s & spl9t]$ p9nacles1 at once rem9ds ! visitor ( ! outl9es ( ! ,cuill9 ,hills ( ,skye4 ,! same features are repeat$ on a less magnific5t scale 9 ,soay & along ! :ole ( ! s\?-we/]n precipit\s coa/-l9e ( ,/4 ,kilda4 ,9 m>k$ contra/ to ^! v>i$ outl9es1 ! ea/]n half ( ,/4 ,kilda rises ) a smoo? gre5 surface1 v>i$ ) %eets ( grey screes1 up to ! r\nd$ summit ( ,conagh]1 ! highe/ po9t 9 ! isl&4 ,if ! d>k crags ( ! re/ ( ! isl& gr\p rem9d "o ( ! ,cuill9s1 ?is ea/]n tract recalls at once ! =m & col\r ( ! ,r$ ,hills ( ,skye4 ,a clos] exam9ation %[s t 9 ea* case ! topography arises f ! influ5ce ( ! v same rocks & geological /ructure z 9 t isl&4 ,!re is1 h[ev]1 "o aspect 9 :i* ,/4 ,kilda has no rival ?r\gh\t ! ,we/]n ,isles4 ,its russet-col\r$ cone1 ?\gh ris+ on ! we/ side ) g5tle gre5 slopes f ! c5tral valley1 plunges on ! ea/]n side 9 "o va/ precipice f a height ( #ajjj feet or m into ! surge at its base4 ,n[h]e among ! ,inn] ,hebrides1 n ev5 on ! s\?-we/]n side ( ,rum1 is !re any su* display ( ! capacity ( ! y\nge/ granite to assume ! mo/ rugg$ & picturesque =ms4 ,x is h>dly possible to exagg]ate ! v>iety ( outl9e assum$ by ! rock z x yields along its sy/em ( jo9ts to ! influ5ce ( a tempe/u\s climate4 ,x has be5 c>v$ into huge project+ buttresses & deep alcoves1 ! nak$ /one gl[+ ) t9ts ( orange & fawn col\r1 veil$ "h & !re ) pat*es ( bright gre5 slope1 or edg$ ) fr+es ( sea-p9k & camomile4 ,e out/&+ ba/ion is r5t ) *asms & split into blocks1 :i* accumulate on ! l$ges l piles ( ru9$ walls4 ,to "o :o boats und]nea? ^! cliffs ! sc5e ( ceaseless de/ruction :i* !y pres5t is vividly impressive4 ,! geology ( ,/4 ,kilda 0 sket*$ by ,maccullo*1 :o recogniz$ ! close resemblance ( its two gr\ps ( rock to ! augite-rock 7gabbro7 & sy5ite 7granophyre7 ( ,skye & o!r isl&s ( ! ,inn] ,hebrides4 ,b he left ! relations ( ! two gr\ps to ea* o!r undet]m9$4#djf ,pr(essor ,h$dle has publi%$ a brief ref]5ce to ! rocks ( ,/4 ,kilda1 )\t1 h[ev]1 (f]+ any def9ite op9ion z to ! geological /ructure ( ! isl&s4#djg ,! be/ acc\nt ( ! geology has be5 giv5 by ,mr4 ,alex&] ,ross1 :o obta9$ evid5ce t ! acid s5ds ve9s into ! basic rock4 ,he br\ght away specim5s cle>ly %[+ ?is relation1 b 9 8 description left ! "q op5 = fur!r inquiry4#djh ,to "s ( ! obs]vations 9 ^! pap]s ref]5ce w be made 9 ! sequel4 ,! foll[+ acc\nt is bas$ on ! results ( two visits paid by me to ,/4 ,kilda 9 ! summ]s ( #ahie & #ahif1 dur+ :i* ,i 0 enabl$ to exam9e ! rocks on l&1 & to sail sev]al times r\nd ! isl&s1 boat+ along ^? p>ts ( ! cliffs :i* pres5t$ features ( special geological importance4 ,footnote #djf3 ,description ( ! ,we/]n ,isles1 vol4 ii4 p4 #ed4 ,footnote #djg3 ,9 an article on ! g5]al geological features ( ! ,out] ,hebrides contribut$ to ,a ,v]tebrate ,fauna ( ! ,out] ,hebrides1 by ,j4 ,a4 ,h>vie-,br[n & ,t4 ,e4 ,buckley1 #ahhh4 ,footnote #djh3 ,briti% ,association ,report1 #ahhe1 p4 #ajdj1 & a mu* full] pap] 9 ! ,proce$+s ( ! ,inv]ness ,field ,club1 vol4 iii4 7#ahhd71 p4 #gb4 ,9 ! ,/4 ,kilda islets ?ree gr\ps ( rock diff]+ f ea* o!r 9 age may be recogniz$4 #a/1 ,a s]ies ( gabbros1 dol]ites & basalts :i* h be5 intrud$ ?r\gh & betwe5 ea* o!r z sills2 #bnd1 a mass ( granophyre :i* invades ^! sills2 & #crd1 abundant dykes & ve9s ( basalt :i* occur bo? 9 ! basic & acid masses4 ,f ! ext5sion ( ! basalt-dykes across ! ,out] ,hebrides x is cle> t ! ,t]ti>y volcanic region rea*$ at lea/ to )9 #fj miles ( ,/4 ,kilda4 ,:e!r or n x /ret*$ ov] ! int]v5+ space n[ ov]fl[$ by ! ,atlantic mu/ be matt] = conjecture4 ,!re c be no d\bt t ! intrusive rocks ( ,/4 ,kilda are 9 age & orig9 ! equival5ts ( ^? ( ! ,inn] ,hebrides4 ,! remnants left ( !m 7 assur$ly n sup]ficial extrusions1 b are *>act]i/ic examples ( ! m deep-seat$ intrusions ( ! ,t]ti>y volcanic p]iod4 ,d[n to ! mo/ m9ute details ( /ructure !y reproduce ! features s well display$ by ! gabbros & granophyres ( ,skye1 ,rum & ,mull4 ,if x is demon/rable 9 ! case ( ^! isl&s t ! intrusions h tak5 place "u a deep cov] ( basalt-%eets1 n[ 9 l>ge "p remov$1 ! inf]5ce may legitimately be drawn t at ,/4 ,kilda a basalt-plateau once exi/$ :i* has be5 m completely de/roy$ ?an 9 ! o!r regions4 ,n a fragm5t ( su* a plateau has surviv$1 unless we may p]haps be all[$ to recognize x 9 "s ( ! basalts enclos$ among ! gabbro-sills4 ,plac$ f> amid ! melan*oly ma9 & expos$ to ! full fury ( ! ,atlantic gales1 ^! islets mu/ be reg>d$ z ! m]e fragm5t>y cores ( a once mu* m ext5sive volcanic area4 ,! geologi/ :o visits !m is deeply impress$ at e turn by ! evid5ce ( ! active & unceas+ de/ruction :i* _! cliffs are und]go+4 ,no?+ n[ rema9s save ! deep-seat$ nucleus ( intrusive sills1 bosses & dykes4 #a4 ,! ,gabbro ,sills4--,! rudely-b$d$ arrangem5t ( ^! rocks is conspicu\s along ! we/ side ( ,/4 ,kilda1 9 ,soay & 9 ,borr]a4 ,!y consi/ ( co>se & f9e v>ieties dispos$ 9 successive %eets :i* dip at angles v>y+ f z little z #ae up to z mu* z #fj or ev5 m4 ,9 ,/4 ,kilda !y =m ! picturesque promontory ( ! ,dune1 & ext5d !nce along ! we/]n side ( ! isl& to its extreme nor!rn end4 ,_! esc>pm5ts face ! ocean1 & _! dip-slopes desc5d t[>ds ! nor?-ea/ 9 grassy declivities to ! s\? bay & ! long v]dant gl5 :i* runs !nce across to ! nor? bay4 ,! same /rike is prolong$ into ,soay1 b fur!r ea/ 9 ,borr]a ! direction curves s z to pres5t va/ esc>pm5ts t[>ds ! we/ & %elv+ %eets ( rock t[>ds ! ea/4 ,none ( ! gabbros se5 by me are z co>se z ! l>ge-gra9$ v>ieties ( ,skye1 nor does !re appe> ev] to be su* a m>k$ b&$ /ructure among !m z t display$ by ! ,cuill9 rocks4 ,fa9t b&+1 h[ev]1 may be notic$4 ,a s]ies ( specim5s :i* ,i collect$ f ! we/ side ( ! isl& has be5 slic$ = microscopic exam9ation1 & ,mr4 ,h>k] has furni%$ me ) ! foll[+ notes reg>d+ !m4 ,an oliv9e-gabbro f ! we/ side ( ,/4 ,kilda #gajg is a d>k1 heavy1 m$ium-gra9$ rock1 9 :i* augite & felsp> are conspicu\s4 ,! microscope %[s1 9 addition1 pl5tiful gra9s ( oliv9e1 ) b little orig9al iron-ore1 & "s apatite-ne$les4 ,! /ructure is ophitic1 ! plates ( pale-br[n augite envelop+ bo? oliv9e & felsp>4 ,a little br[n hornbl5de & r$-br[n mica are probably orig9al1 ! rock %[+ little sign ( alt]ation4 ,! felsp> is labradorite1 ) albite- & ,c>lsbad-tw9n+1 & =ms elongat$ rectangul> cry/als4 ,ano!r specim5 #gajh is a rock ( simil> appe>ance b some:at co>s] texture1 & /ructurally is a m typical gabbro ?an ! prec$+1 ! felsp> hav+ little ( ! 'la?' %ape1 :ile ! augite1 ?\gh /ill m\ld$ on ! felsp>1 sc>cely assumes an ophitic habit4 ,a /rik+ feature 9 ?is rock is ! way 9 :i* ! augite is cr[d$ ) 's*ill]'-inclusions1 9 places s closely z to be almo/ opaque4 ,a high magnification %[s t ^! inclusions are d>k1 l9e> 9 =m1 & dispos$ along two directions int]sect+ at a high angle4 ,! labradorite has unusually close tw9-lamellation on bo? albite & p]icl9e laws1 & x is possible t ?is is a /ra9-effect4 ,a ?ird specim5 #gaji is f a rock 9 e respect id5tical ) ! prec$+1 except t ! oliv9e is r m pl5tiful1 & 9 "s gra9s is p>tially s]p5t9iz$4 ,:ile ! gabbros ( ,/4 ,kilda are n a m]e uni=m boss1 b a s]ies ( sills & irregul> masses :i* h be5 successively inject$ into ea* o!r1 !y h subsequ5tly be5 cut ?r\gh by _m basalt-dykes & ve9s4 ,^!1 :i* are sometimes z abundant z 9 ! gabbro ( ! ,cuill9 ,hills1 trav]se ! rocks bo? 9 ! l9e ( b$d+ & also at _m diff]5t angles across x4 ,z !y g5]ally wea!r fa/] ?an ! gabbros1 !y give rise to deep n>r[ clefts :i* may be trac$ up ! :ole height ( ! precipices1 occasion+ sea-caves bel[ & %>p not*es on ! cre/s above4 ,^! sc5ic features1 s indicative ( ! geological /ructure t causes !m1 are specially well se5 on ! we/]n face ( ! ,dune or s\?-we/]n promontory ( ! isl&1 & likewise 9 ! /rangely rift$ precipices fur!r nor? & 9 ,soay4 ,!y are1 h[ev]1 mo/ impressively display$ ar\nd ! nak$ walls ( ,borr]a1 :i* 9 _! m>vell\s comb9ation ( spiry ridges1 deep /raight gullies1 & spl9t]$ cre/s1 rem9d "o at e turn ( ! sc5]y ( ,blav5 & ! ,cuill9 ,hills4 #b4 ,! ,granophyre ,boss & its ,apophyses4--,! ea/]n half ( ! isl& ( ,/4 ,kilda consi/s ( a pale rock :i* ,maccullo* long ago id5tifi$ ) ! granophyre ( ,skye1 & :i*1 z he po9t$ out1 has mu* resemblance to p>ts ( ! granite ( ,arran4#dji ,n only does x give rise to topographical =ms l ^? ( ! ,r$ ,hills1 b x wea!rs1 l ! ,skye granophyre & ! ,arran granite1 into ?ick b$-l %eets divid$ by transv]se jo9ts into l>ge quadrangul> blocks4 ,on clos] inspection x is f\nd to resemble /ill m precisely ! acid rocks ( ! ,inn] ,hebrides4 ,x possesses ! same drusy micropegmatitic /ructure z ! granophyres ( ,skye1 ,rum & ,mull4 ,! f]ro-magnesian con/itu5ts are pres5t 9 small quantity1 h5ce ! pale hue ( ! /one4 ,! qu>tz & felsp> project 9 well-t]m9at$ cry/als into ! drusy cavities1 :i* are sometimes fur!r adorn$ ) delicate tufts ( cle> cry/alliz$ epidote4 ,9 ^! & o!r respects ! rock displays ! famili> ext]nal =ms ( ! y\ng] or ,t]ti>y granites ( ,brita94 ,footnote #dji3 ,description1 vol4 ii4 p4 #ed4 ,mr4 ,h>k]'s notes on ! microscopic /ructure ( ?is granophyre are z foll[s3--,! prevail+ felsp> is or?oclase1 (t5 v turbid f second>y products4 ,ev5 :at appe> to be di/9ct cry/als are sometimes se5 9 ! slices to be invad$ on ! m>g9 by qu>tz 9 r\gh micrographic int]gr[?s1 & mu* ( ! f9] int]gr[? occurs z a fr+e to ! cry/als4 ,9 ?is case ! felsp> ( ! micropegmatite c (t5 be v]ifi$ to be 9 cry/all9e cont9uity ) ! cry/al :i* has s]v$ z a nucleus #ffbd4 ,qu>tz occurs 9 di/9ct cry/als & gra9s z well z 9 ! micropegmatite4 ,!re is a m granitoid v>iety ( ! rock1 9 :i* only a v rude approa* to micrographic int]gr[?s is se5 #ffbc4 ,9 bo? v>ieties !re is b little trace ( any f]ro-magnesian m9]al2 ! m typical granophyre has :at seems to be de/roy$ augite1 :ile ! granitoid rock conta9s a little deep-br[n biotite4 ,scatt]$ cry/al-gra9s ( magnetite occur 9 bo?4 ,n>r[ ribbon-l ve9s ( a f9] mat]ial1 sometimes only an in* 9 bread?1 trav]se ! ord9>y granophyre4 ,simil> ve9s run ?r\gh ! rock ( ! ,r$ ,hills 9 ,skye2 !y are %>ply def9$ f ! enclos+ rock1 z if ! latt] _h already solidifi$ be=e _! intrusion4 ,) reg>d to ! microscopic /ructure ( "s ?9 slices prep>$ f ^! ve9s1 ,mr4 ,h>k] rem>ks t ! mat]ial ( ! ve9s is ( a type int]m$iate betwe5 granophyre & microgranite #ffbb1 #ffbc4 ,! *ief bulk is a f9ely-granul> aggregate ( qu>tz & felsp>1 ! latt] v turbid2 b 9 ?is aggregate are imb$d$ num]\s pat*es ( micropegmatite1 (t5 ( p]fect & delicate /ructure4 ,^! areas ( micropegmatite %[ "s approa* to a radiate or rudely sph]ulitic /ructure1 &1 9 "s cases1 are clu/]$ r\nd a cry/al ( felsp> or qu>tz4 ,"s granules ( magnetite & r>e flakes ( br[n biotite are ! only o!r con/itu5ts ( ! rock4 ,al?\gh !y mu/ be ( some:at lat] date1 !re is evid5tly no?+ 9 ! petrographical *>act]s ( ^! f9e-textur$ ve9s to sep>ate !m widely f ! ord9>y granophyres ( ! region4 ,^! ve9s may be comp>$ ) ! sph]ulitic dyke t trav]ses ! granophyre ( ,meall ,de>g at ! head ( ,gl5 ,sliga*an 7describ$ at p4 #cha71 :i*1 ?\gh und\bt$ly some:at y\ng] ?an ! rock t conta9s x1 yet pres5ts ! v same /ructures z are visible at ! m>g9 ( t rock4#daj ,! mat]ial ( ?is dyke & ( ! f9] ve9s ( ,/4 ,kilda & ! ,r$ ,hills probably belongs to a lat] p]iod ( protrusion f a deep] unconsolidat$ portion ( ! same acid magma z at fir/ suppli$ ! g5]al body ( granophyre4 ,footnote #daj3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid71 p4 #bbj4 ,und\bt$ly ! mo/ int]e/+ feature 9 ! granophyre ( ,/4 ,kilda is its junction ) ! mass ( basic rock to ! we/ ( x4 ,?is junction-l9e runs f ab\t ! middle ( ! *ief or s\? bay 7:]e1 h[ev]1 its precise position is conceal$ "u detritus7 across ! isl& to ! nor? %ore1 :]e x desc5ds ! face ( ! precipice & plunges "u ! sea4 ,important z ! actual contact ( ! two rocks obvi\sly is 9 reg>d to _! relative date1 x has n hi!rto be5 obs]v$ or describ$4 ,maccullo* notic$ num]\s fragm5ts ( trap p5etrat$ by ve9s ( sy5ite1 b he did n see ^! rocks 9 place1 &1 9 spite ( _! app>5t te/imony to ! po/]iority ( ! acid intrusions1 he 0 incl9$ to believe t ! ve9s 7 n real ve9s1 b t ! trap & sy5ite _h a common orig9 & w\ld be f\nd to pass into ea* o!r1 z he ?\ght also occurr$ 9 ,mull & ,rum4 ,9 rec5t ye>s ,mr4 ,alex&] ,ross1 dur+ 8 visit to ,/4 ,kilda1 collect$ specim5s illu/rat+ ! v>ieties ( gabbro1 dol]ite & basalt1 & %[+ ! intrusion ( ! acid into ! basic rocks4 ,z already /at$1 he 0 dispos$ to reg>d ! granite z ( y\ng] date ?an ! gabbros1 b left ! "q undecid$4#daa ,footnote #daa3 ,9 8 pap]1 ,proce$4 ,inv]ness ,field ,club1 vol4 iii4 7#ahhd71 p4 #gh1 ,mr4 ,ross quotes a lett] f ,pr(4 ,judd1 :o !re /ates t ! rock suppos$ to be granite is se5 "u ! microscope to be a q diff]5t rock--a qu>tz-diorite4 ,"s ( ! specim5s f ,/4 ,kilda collect$ by ,mr4 ,ross 7 exhibit$ at a meet+ ( ! ,geological ,society on #be? ,janu>y #ahic4 ,) reg>d to ^! ,pr(4 ,judd1 9 ! c\rse ( ! discussion on 8 pap] on ,inclusions ( ,t]ti>y ,granite 9 ! ,gabbro ( ! ,cuill9 ,hills1 rem>k$3--,!y %[ a d>k rock trav]s$ by ve9s ( a light "o1 b ! d>k rock is n a gabbro & ! light "o is n a granite 7,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlix4 7#ahic71 p4 #aih74 ,! be/ locality = ! exam9ation ( ! junction ( ! ma9 granophyre mass ) ! gabbros is inaccessible save by boat1 & only 9 ! calme/ wea!r4 ,x occurs 9 ! great cliff on ! nor!rn side ( ! isl& betwe5 ! nor? bay & ! sea-/ack kn[n z ! ,brag/ack4 ,! l9e ( contact em]ges f bel[ ! sea-level1 & asc5ds ! cliff ) a we/w>d incl9ation ( f #fj to #hj4 ,"h1 z 9 ,skye1 ! acid rock und]lies ! basic masses1 :i* are rudely b$d$ & mu* jo9t$4 ,ab\t #aej feet above ! sea-level1 ! ne>ly v]tical cliff breaks up into an exce$+ly rocky & rugg$ acclivity1 across :i* ! junction seems to slope at a l[] angle4 ,b ! place is h>dly rea*able1 save p]haps by ! intrepid1 b>efoot$ cragsm5 ( ,/4 ,kilda4 ,illu/ration3 ,fig4 #cfb4--;,junction ( granophyre & gabbro1 nor? side ( ,/4 ,kilda4 ,along ! %>ply def9$ l9e ( contact ! granophyre is close-gra9$1 & s5ds a network ( ve9s into ! d>k %eets ( gabbro4 ,! g5]al features ( ! junction are repres5t$ 9 ,fig4 #cfb4 ,! ve9s are n>r[1 ^? ne>e/ ! ma9 body ( granophyre div]g+ f x at a /ill m acute angle ?an ^? f ! mass ( ,meall ,de>g 7,fig4 #cgf71 & !n bran*+ s z to enclose masses ( ! gabbro & to run across !m 9 long p>allel ve9s4 ,a *>act]i/ic feature ( _m ( ^! ve9s1 besides _! n>r[ness1 is _! t5d5cy to split up at ! ends into m]e f+]s & ?reads z repres5t$ 9 ,fig4 #cfc4 ,ow+ to ! dep? ( soil on ! cultivat$ l&1 & ( b\ld]s & s& on ! bea*1 ! actual junction ( ! ma9 body ( granophyre ) ! gabbro is n se5 on ! s\!rn %ore4 ,b a few y>ds to ! we/w>d ( :]e x mu/ lie1 ! bea* is cumb]$ ) l>ge blocks ( rock brok5 up f ! mass1 :i* c be se5 9 situ a little fur!r s\? =m+ a l9e ( l[ cliff ) a rugg$ =e%ore4 ,^! rocks consi/ ( v>i\s gabbros & basalts ( r f9e gra91 pr(usely trav]s$ ) ve9s ( :ite granophyre4 ,"s ( ^! ve9s are two feet or m 9 bread?1 &1 :5 ( t size1 %[ ! di/9ctive granul> texture & drusy /ructure ( ! ma9 "p ( ! acid rock4 ,b f ^! dim5sions !y c be trac$ ?r\gh e /age ( dim9ution until !y become m]e ?reads4 ,:5 !y are only an in* or two broad1 !y assume a f9ely granul> texture l t ( ! ve9s t run ?r\gh ! body ( ! granophyre4 ,illu/ration3 ,fig4 #cfc4--,ve9s ( granophyre trav]s+ gabbro & splitt+ up into ?9 ?reads1 nor? side ( ,/4 ,kilda4 ,! am\nt ( inject$ mat]ial 9 ! d>k basic rocks is "h & !re s great z to =m a k9d ( breccia 7,fig4 #cfd71 :i*1 f ! contra/ ( tone betwe5 its two con/itu5ts1 makes a conspicu\s object on ! %ore4 ,"h1 z 9 ! example already cit$ f ,rum1 ! basic rocks seem to h be5 %att]$ into fragm5ts1 & ! acid mat]ial to h be5 inject$ into ! m9ute/ int]/ices betwe5 !m4 ,! enclos$ fragm5ts are ( all sizes f m]e gra9s up to blocks a foot or m 9 l5g?4 ,!y are g5]ally angul>1 l rock-*ips f a qu>ry4 ,moreov]1 !y are n all ( ! same k9d ( mat]ial4 ,:ile at ?is locality mo/ ( !m consi/ ( basalt1 !y include also a few l>ge & small pieces ( r co>se gabbro4 ,!re has evid5tly be5 a c]ta9 am\nt ( transport ( mat]ial1 z well z an ext5sive disruption ( ! rocks 9 situ4 ,! granophyre "h & !re assumes a d>k] or gre5] t9t1 z if x _h dissolv$ & absorb$ "s portion ( ! old] rock4 ,/ill m a/oni%+ are ! sections to be se5 on ! we/]n cliffs & rocky declivities ( ! ridge to ! nor? ( ! ,dune1 at a di/ance ( p]haps #ejj or #fjj y>ds we/w>ds f ^? ( ! ,s\? ,bay4 ,"h ! gabbro-%eets are trav]s$ by a numb] ( conspicu\s :ite b&s1 :i* on exam9ation prove to be ve9s or dykes ( granophyre4 ,z view$ f ! sea1 ! g5]al disposition ( ! two gr\ps ( rocks is repres5t$ 9 ,fig4 #cff4 ,! broade/ mass ( granophyre breaks out t[>ds ! bottom ( ! precipice1 & slants upw>d z a %eet int]calat$ betwe5 ! gabbro sills1 ) a bread? ( ab\t #dj or #ej feet1 b rapidly ?9n+ away 9 its asc5t4 ,"o ( ! b&s bel[ x has a bread? ( ab\t #ae feet4 ,! mat]ial ( ^! intrusions is a pale f9e-gra9$ granophyre l t ( ! ,s\? ,bay1 ,i did n detect1 ei!r "h or any:]e else 9 ,/4 ,kilda1 a def9ite sph]ulitic /ructure su* z is s common 9 ! granophyre dykes ( ,skye4 ,illu/ration3 ,fig4 #cfd4--,pale granophyre inject$ into d>k basalt1 ,s\? ,bay1 ,/4 ,kilda4 ,! crags on ! fur!r side ( ! bay are ! gabbro %eets ( ! ,dune4 7,f a photograph by ,colonel ,evans47 ,?\gh ! acid intrusions are some:at irregul> bo? 9 ?ickness & direction1 !y lie g5]ally p>allel to ea* o!r 9 ! l9e ( /rike ( ! b$d+ ( ! gabbros4 ,!y are no d\bt apophyses f ! ma9 body ( granophyre1 :i* em]ges to ! surface ab\t a ?ird ( a mile to ! ea/w>d1 b may ( c\rse be at no great dep? und]nea?4 ,illu/ration3 ,fig4 #cfe4--,ve9s ( granophyre trav]s+ a l9e-gra9$ gabbro & sc>cely ent]+ a co>se-gra9$ %eet1 we/ side ( ,rueval1 ,/4 ,kilda4 ,besides ! broad] b&s ( acid rock1 & div]g+ f !m1 a complicat$ network ( ve9s ramifies 9 all directions ?r\gh ! gabbros1 z at ! ,s\? ,bay4 ,! extraord9>y degree to :i* ! basic rocks h be5 %att]$ into fragm5ts is /rik+ly display$ "h1 likewise ! extreme liquidity ( ! acid magma1 :]eby x 0 able to ins9uate itself into e *9k & cranny4 ,b ! obs]v] notices t ?is condition ( excessive disruption is n %>$ by all ! basic sills1 & is n att5dant ^u all ! acid dykes4 ,z an example ( ?is irregul> di/ribution ( ! /ructure1 ,i give ! accompany+ sket* 7,fig4 #cfe71 :]e a f9e-gra9$ gabbro has be5 completely brok5 up & int]sect$ ) granophyre ve9s1 :ile ! co>s] %eet ov]ly+ x has almo/ entirely escap$4 ,! d>k basalt-l %eets appe> g5]ally to h be5 mu* m disrupt$ ?an ! m l>gely-cry/all9e v>ieties4 ,x is noticeable "h1 also1 t ! fragm5ts entangl$ 9 ! network ( granophyre ve9+s d n entirely belong to ! rock t has be5 %att]$1 b sometimes include l>ge & small lumps ( diff]5t gabbros1 %[+ "s transf]5ce ( mat]ial ) ! inru% ( ! acid magma4 ,?\gh clos] 9 gra9 :]e x comes 9 contact ) ! gabbro1 ! granophyre nev] assumes any vitre\s texture along its m>g94 ,a s]ies ( ?9 slices1 prep>$ f specim5s collect$ by me 9 ! ,s\? ,bay 9 ! summ] ( #ahie1 0 exam9$ by ,mr4 ,h>k]1 :o furni%$ ! foll[+ notes reg>d+ !m3--,! basalt trav]s$ by ! granophyre is a f9e-textur$ v>iety ) small porphyritic felsp>s4 ,^! latt] seem to be usually unalt]$1 reta9+ ! glass cavities :i* 9 "s ( ! cry/als are abundant4 ,! gr\ndmass1 h[ev]1 %[s m9]als ( metamorphic orig9 :i* mu/ be d]iv$ ma9ly f ! orig9al augite4 ,a br[n mica is ! mo/ conspicu\s2 b ) x are associat$ "s br[ni%-gre5 hornbl5de & c]ta9 *loritic & p]haps s]p5t9\s sub/ances4 ,x is *iefly ne> ! m>g9 ( a fragm5t ( basalt t ! mica gives place to ^! m9]als4 ,! basalt /ill reta9s pl5ty ( unalt]$ granules ( augite 9 ! c5tral p>ts ( a fragm5t4 ,x is n c]ta9 t ! second>y m9]als nam$ come exclusively f ! augite ( ! basalt2 f _! =m & mode ( occurr5ce !y may 9 "p h replac$ oliv9e or ev5 rhombic pyrox5e4 ,illu/ration3 ,fig4 #cff4--,view ( sills & ve9s ( pale granophyre trav]s+ d>k %eets ( gabbro1 we/ side ( ,/4 ,kilda4 7,f a photograph by ,colonel ,evans47 ,! acid rock1 ?\gh /yl$ granophyre above1 belongs to a granitoid v>iety ( t gr\p ( rocks1 & has b little indication ( micrographic /ructures4 ,comp>$ ) ! o!r granophyres f ,/4 ,kilda1 slic$ & exam9$1 ^! examples %[ a less acid composition4 ,?is is express$ m9]alogically 9 ! pres5ce ( a some:at l>g] proportion ( f]ro-magnesian m9]als & ( soda-lime felsp>4 ,^! features might inde$ be mat*$ 9 _m normal granophyres among ! ,we/]n ,isles1 b 9 ! pres5t case x c h>dly be d\bt$ t !y are to be expla9$1 at lea/ 9 "s degree1 by ! acid magma hav+ tak5 up a c]ta9 am\nt ( mat]ial f ! basalt4 ,_m ( ^! ,t]ti>y granophyres h und\bt$ly be5 modifi$ by ! incorporation ( pieces ( basalt & gabbro1 & a collection made 9 ! ,/ra? di/rict ( ,skye w furni% examples = future /udy4 ,pr(essor ,sollas's description ( simil> ph5om5a 9 ! ,c>l+=d di/rict has already prov$ ! importance ( ?is k9d ( action4#dab ,9 ! pres5t in/ance1 bo? br[n mica & hornbl5de occur pl5tifully 9 ! granophyre1 & especially r\nd ! basalt fragm5ts4 ,?is latt] po9t is conclusive z to ! d]ivation ( ! basic mat]ial1 & fur!r proves a c]ta9 degree ( viscosity 9 ! acid magma at ! "t ( its intrusion4 ,footnote #dab3 ,trans4 ,roy4 ,iri% ,acad4 vol4 xxx4 7#ahid71 pp4 #dgg-egb4 ,ano!r s]ies ( specim5s :i* ,i collect$ 9 ! foll[+ ye> 0 submitt$ to ,mr4 ,h>k] = petrographical det]m9ation1 & 8 obs]vations on two ( ! microscopic slices are z foll[3 ,a breccia f ! ,s\? ,bay1 ,/4 ,kilda #gaje1 consi/s ( angul> fragm5ts up to two in*es 9 diamet] set 9 a matrix ( grey granophyre ( m$ium texture4 ,! fragm5ts belong to two types--"o ( v close texture 7basalt71 ! o!r m evid5tly cry/all9e 7diabase74 ,bo? are cut by ! slice4 ,! basalt %[s v evid5t metamorphism1 its augite be+ :olly trans=m$ into gre5i%-br[n hornbl5de4 ,! little felsp>-la?s & granules ( iron-ore seem to be unalt]$1 ?\gh ! latt] may p]haps h contribut$ to ! =mation ( ! hornbl5de4 ,ano!r fragm5t ( basalt has "s l>g] cry/al-gra9s ( augite1 & ^! are n conv]t$ into hornbl5de4 ,! diabase %[s a less m>k$ b\nd>y "u ! microscope1 b o!rwise has simil> *>act]s to ! prec$+4 ,! /riat$ felsp>-cry/als & gra9s ( iron-ore h n be5 re-cry/alliz$4 ,a consid]able am\nt ( pale augite rema9s1 b !re is also pl5ty ( deeply-col\r$ hornbl5de1 bo? fibr\s & compact4 ,?is diabase is c]ta9ly an intrusive rock1 b ! basalt1 f its petrographic "*1 might be f a lava-fl[ or f a dyke4 ,! granophyre is ( some:at co>se texture1 ! micrographic /ructure be+ only ( a rude type4 ,x is notably ri*] 9 ! d>k] con/itu5ts ?an is usual 9 su* rocks4 ,fur!r1 ! hornbl5de & magnetite t5d to clu/] 9 little pat*es :i* sugge/ de/roy$ fragm5ts ( basic rocks4 ,a gra9 or two ( sph5e occur1 a m9]al =eign to ! normal granophyres4 ,ano!r simil> specim5 #gajf f ! same locality %[s a basic rock ( co>s] texture1 approa*+ "s ( ! gabbros 9 appe>ance & ) b\nd>ies 9 places n v %>ply def9$4 ,! grey matrix is aga9 relatively ri* 9 ! d>k elem5ts1 & ! mann] 9 :i* !y occur 9 little pat*es1 l ne>ly oblit]at$ 'x5oli?s1' po9ts unmi/akably to a c]ta9 am\nt ( absorption ( basic mat]ial by ! acid magma1 ) consequ5t enri*m5t 9 ! f]ro-magnesian m9]als4 ,! slice cuts only ! acid rock1 :i* is se5 to be ( granitoid r ?an granophyric /ructure1 ?\gh ! t5d5cy ( ! felsp> to enclose qu>tz-gra9s is unlike a typical granite4 ,oligoclase1 ) comb9$ albite- & ,c>lsbad-tw9n+1 is well repres5t$ 9 addition to or?oclase1 & "s zon$ cry/als seem to be ( albite ) a bord] ( oligoclase4 ,br[n hornbl5de & a little br[n mica are ! col\r$ con/itu5ts4 ,magnetite & apatite are also obs]v$4 ,! te/imony ( ! rocks ( ,/4 ,kilda to ! po/]iority ( ! granophyre to ! gabbros & basalts is ?us cle> & emphatic4 ,x entirely confirms my previ\s obs]vations reg>d+ ! ord] ( sequ5ce ( ^! rocks 9 ,mull1 ,rum & ,skye4 ,b ! ,/4 ,kilda sections display1 ev5 m /rik+ly ?an c be usually se5 9 ^! isl&s1 ! intricate network ( ve9s :i* proce$ f ! granophyre1 ! %att]$ condition ( ! basic rocks :i* ^! ve9s p5etrate1 ! rem>kable liquidity ( ! acid magma at ! "t ( its intrusion1 & ! solv5t action ( ?is magma on ! basic fragm5ts :i* x envelop$4 #c4 ,! ,basic ,dykes4--,ref]5ce has already be5 made to ! num]\s dykes by :i* ! gabbros ( ! ,/4 ,kilda gr\p ( islets is trav]s$4 ,simil> dykes occur also1 ?\gh less pl5tifully1 9 ! granophyre4 ,x rema9s = future obs]vation to det]m9e :e!r !re is "o s]ies old] & ano!r lat] ?an ! intrusion ( ! acid rock4 ,9 any case1 x is q c]ta9 t ! dykes 9 ! gabbro d n all belong to "o p]iod ( injection1 = frequ5t examples ( int]section may be notic$1 especially on ! cliffs ( ,borr]a1 & also cases ( d\ble & ev5 treble dykes :i* h be5 =m$ by successive infill+s )9 ! same fissure4 ,! rem>kably v>i$ precipices ( t isl& are m>k$ by ! long n>r[ rifts left by ! wea!r+ ( v]tical dykes1 :i*1 z above rem>k$1 may be foll[$ ) ! eye f ! sea-level to ! sky-l9e1 asc5d+ obliquely across ! b$d+ ( ! gabbro %eets4 ,ano!r gr\p ( dykes may be trac$ slop+ upw>d at l[ angles along ! face ( ! cliffs & af=d+ admirable l$ges ) ov]>*+ ro(s = innum]able gannets1 kittywakes & guillemots4 ,o!r dykes & ribbon-l ve9s may be se5 trav]s+ ! gabbro 9 _m diff]5t directions1 precisely z among ! ,cuill9 ,hills4 ,z no simil> network ( dykes & ve9s is to be obs]v$ 9 ! granophyre1 ,i am dispos$ to reg>d a l>ge numb] ( ^! intrusions z old] ?an t rock4 ,b ,i did n obs]ve any actual example ( a basic dyke truncat$ by ! granophyre4 ,!re c be no d\bt1 h[ev]1 t an injection ( simil> dykes & ve9s took place aft] ! invasion ( ! granophyre4 ,^! lat] intrusions are conspicu\sly display$ along ! cliffs t ext5d f ! gabbro junction on ! nor? side ( ,/4 ,kilda r\nd ! ea/]n coa/ into ! ,s\? ,bay4 ,!y ma9ta9 a g5]al p>allelism & asc5d f ! sea-level at v>y+ angles ( incl9ation1 runn+ up ! pale sea-wall z d>k b&s4 ,!y consi/ ( basalt-rocks1 & may (t5 be se5 to bran* & to die out4 ,l ^? 9 ! gabbro1 !y are n infrequ5tly comp\nd1 be+ made up ( two or ?ree or ev5 m di/9ct dykes4 ,?is is well se5 on ! great precipice bel[ ,cona*]1 :]e ! section giv5 9 ,fig4 #cfg is display$4 ,"h 9 a v]tical height ( ab\t #hjj or #ijj feet1 !re mu/ be at lea/ sev5 dykes1 simple & comp\nd4 ,a little fur!r s\? a triple dyke may be se5 to be compos$ ( a ?ick c5tral zone & two ?9n] m>g9al b&s1 ( :i* ! l[] /rikes (f f ! o!rs & ma9ta9s an indep5d5t c\rse ?r\gh ! granophyre 7,fig4 #cfh74 ,illu/ration3 ,fig4 #cfg4--,section ( ! sea-cliff bel[ ,cona*]1 ,/4 ,kilda1 %[+ basic dykes 9 granophyre4 ,illu/ration3 ,fig4 #cfh4--,triple basic dyke1 sea-cliff1 ea/ side ( ,/4 ,kilda4 ,v4 ,,! ,,granite ,,( ,,arran ,! nor!rn half ( ! isl& ( ,arran is ma9ly occupi$ by "o ( ! mo/ compact & picturesque gr\ps ( granite m\nta9s 9 ,scotl&4#dac ,^! heights1 ris+ out ( ! ,fir? ( ,clyde to a height ( #bhff feet1 pres5t1 9 _! spiry & s]rat$ cre/s1 a contra/ to ! smoo!r cont\rs ( ! old] granitic elevations ( ?is c\ntry4 ,! granite is surr\nd$ by a r+ ( s*i/ose rocks1 belong+ to ! metamorphic s]ies ( ! ,s\!rn ,highl&s1 save = a %ort di/ance on ! ea/]n m>g91 :]e x comes 9 contact ) & indurates ! ,l[] ,old ,r$ ,s&/one4 ,maccullo* long ago po9t$ out t no pebbles ( ! granite are to be f\nd 9 ! surr\nd+ conglom]ates & r$ s&/ones ( ,c>bonif]\s & y\ng] age4#dad ,geologi/s accord+ly came to ! conclusion t ! protrusion ( ! granite took place aft] ,c>bonif]\s "t1 & h5ce t x _h no connection ) ! appe>ance ( ! f> old] granites ( ! ,highl&s4 ,9 ! ye> #ahgc ,i gave reasons = believ+ ! granite to be n only y\ng] ?an ! ,c>bonif]\s =mations1 b to be ref]able ) mo/ probability to ! ,t]ti>y volcanic s]ies4#dae ,! progress ( inquiry has t5d$ to confirm ?is inf]5ce1 ?\gh no direct pro( ( its correctness has be5 obta9$4 ,two l9es ( inve/igation may be pursu$1 & ea* leads to ! conclusion ( ! probability ( ! ,t]ti>y age ( ! granite4 ,"o ( ^! proce$s on a comp>ison ( ! petrographical *>act]s ( ! ,arran rocks ) ^? ( und\bt$ memb]s ( ! ,t]ti>y s]ies among ! ,we/]n ,isles4 ,! o!r inquiry deals ) ! relation ( ! rocks to ea* o!r 9 ! g5]al geological /ructure ( ,arran itself4 ,footnote #dac3 ,! rocks ( ,arran h (t5 be5 describ$4 ,besides ! "w ( ,maccullo* above quot$1 ref]5ce may be made to ! pap] by ,s$gwick & ,mur*ison1 ,trans4 ,geol4 ,soc4 #bnd ,s]4 vol4 iii4 p4 #ba2 ,a4 ,c4 ,ramsay's ,geology ( ! ,isl& ( ,arran1 #ahda1 ! pap] ( ,neck] de ,saussure quot$ on p4 #dab2 ,j4 ,bryce's ,geology ( ,clydesdale & ,arran1 #crd edit4 #ahfe4 ,! isl& is at pres5t be+ survey$ = ! ,geological ,survey by ,mr4 ,w4 ,gunn4 ,footnote #dad3 ,description ( ! ,we/]n ,isl&s ( ,scotl&1 vol4 ii4 p4 #chh4 ,footnote #dae3 ,trans4 ,ed94 ,geol4 ,soc4 vol4 ii4 "p iii4 ,maccullo* fir/ rem>k$ ! /rong li?ological resemblance ( ! ,arran granite to ! sy5ite1 or granophyre1 ( ,skye & ,/4 ,kilda4#daf ,m rec5t petrographical inve/igation1 z already /at$1 has furni%$ additional pro(s ( ! connection betwe5 ! acid rocks ( ^! isl&s4 ,s closely inde$ are ^! rocks l9k$ by megascopic & microscopic *>act]s1 t ! petrologi/ has no hesitation 9 plac+ !m toge!r z probably products ( ! same p]iod ( igne\s activity4 ,footnote #daf3 ,description1 vol4 ii4 p4 #ceb4 ,f ! g5]al geological /ructure ( ,arran1 a fur!r /rong argum5t may be d$uc$ 9 fav\r ( ! late date ( ! eruptions ( granite4 ,good reasons h be5 giv5 = class+ z ,p]mian ! bright r$ s&/ones :i* occupy mu* ( ! c5tral & s\!rn p>ts ( ?is isl&1 & include ! little volcanic gr\p already ref]r$ to4 ,^! s&/ones h be5 invad$ by a complex s]ies ( eruptive rocks :i* w\ld ?us be lat] ?an ! ,p]mian p]iod4 ,no igne\s masses po/]ior to ?is p]iod are c]ta9ly kn[n 9 ,brita9 save ^? ( ,t]ti>y age4 ,! l>g] body ( granite 9 ! nor!rn half ( ! isl& n[h]e comes into direct contact ) ! new] r$ s&/ones1 b ^! /rata are pi]c$ by small] bodies ( granite4 ,h5ce1 bo? by ! evid5ce ( _! int]nal /ructure & by ! /ratigraphy ( ! gr\nd1 ! lat] igne\s rocks ( ,arran may be reasonably gr\p$ toge!r z "o important & consecutive s]ies1 comp>able 9 age & g5]al *>act]s ) ^? ( ,t]ti>y date 9 ! ,inn] ,hebrides4 ,illu/ration3 ,fig4 #cfi4--;,jo9t$ /ructure ( ! granite ne> ! top ( ,goatfell ,arran4 7,f a photograph by ,mr4 ,w4 ,d\glas1 l5t by ! ,scotti% ,m\nta9e]+ ,club47 ,! igne\s rocks ( ,arran1 lat] ?an ! probably ,p]mian s&/ones1 range f acid to basic 9 composition4 ,besides ! nor!rn granite1 !re are 9 ! s\!rn "p ( ! isl& acid rocks t include granite1 co>se-gra9$ qu>tz-porphyry & f9e-gra9$ felsite4 ,:]e ! relations ( ^! rocks to ea* o!r c be se51 ! felsite is f\nd by ,mr4 ,gunn to be new] ?an ! porphyry1 into :i* x s5ds sills & dykes4 ,a feature obs]v$ by ! same geologi/ 9 ,arran (f]s a fur!r po9t ( resemblance to ! acid sills & dykes ( ,skye4 ,he has notic$ t accompany+ ! qu>tz-porphyry ( ,drumadoon & ,b5nan1 a mass ( basic rock =ms a k9d ( fr+e or selvage r\nd x1 sometimes ) :at appe>s to be a rock ( int]m$iate "* betwe5 !m4 ,basic sills are abundant s\? ( ,gl5 ,a%dale1 ?\gh to ! we/ ( ,:it+ ,bay mo/ ( ! intrusive %eets are ( acid mat]ial4 ,"s ( ! qu>tz-porphyry %eets are m>k$ly column>4 ,"o ( !m1 ne> ,corriegills1 displays a div]g5t gr\p+ ( ! prisms1 n unlike p>ts ( ! pit*/one %eets ( ,eigg & ,hysgeir1 & sugge/ive ( ! rock hav+ fl[$ along a holl[ l t ( a valley4 ,no c]ta9 trace1 h[ev]1 has be5 f\nd ( any ,t]ti>y lava-/ream 9 ,arran1 nor has evid5ce ( tuffs be5 detect$ 9 any "p ( ! y\ng] igne\s s]ies4 ,all ! rocks appe> to be intrusive1 ?\gh s abundant & v>i$ are !y z to indicate t !y belong to a vigor\s eruptive c5tre1 :i* may h p\r$ out at ! surface lavas & a%es1 s9ce entirely remov$ by d5udation4 ,! num]\s basic dykes = :i* ! s\? end ( ,arran has long be5 celebrat$ h a g5]al nor!rly tr5d1 & appe> to be all ( ! same or ne>ly ! same age4 ,!y und\bt$ly cut ?r\gh ! qu>tz-porphyries & ! co>se-gra9$ basic sills1 b are less num]\sly visible 9 ! f9]-gra9$ basic sills1 :ile 9 ! felsitic %eets !y are seldom to be se54 ,9 sev]al places dykes runn+ 9 an ,e4,n4,e4 direction cut ! o!rs1 & are !re=e ( lat] date4#dag ,! comp\nd dykes ( ,tormore on ! we/ side ( ! isl& h be5 already notic$ 7p4 #afa74 ,footnote #dag3 ,ann4 ,rep4 ( ,geol4 ,surv4 = #ahid1 p4 #bhf4 ,,vi4 ,,! ,,nor?-,,ea/ ,,( ,,irel& ,9 ! nor?-ea/]n c\nties ( ,irel& !re are two regions :i* af=d ample mat]ial = discussion 9 connection ) ! protrusion ( acid rocks dur+ ! ,t]ti>y volcanic p]iod4 ,"o ( ^!1 :i* = di/9ction may be call$ ! ,c>l+=d region1 embraces ! tract ( c\ntry :i* includes ! ,m\rne ,m\nta9s on ! nor?-ea/ side ( ,c>l+=d ,l\gh & ! ranges ( ,slieve ,foye & ,slieve ,gullion on ! s\?-we/ side4 ,! o!r lies ma9ly )9 ! basaltic plateau1 ! l>ge/ ( its scatt]$ portions =m+ p>ts ( ! hills ( ,c>ne>ny & ,t>dree 9 ! c\nty ( ,antrim 7,map ,,vii474 #a4 ,! ,c>l+=d ,region a4 ,! ,m\rne ,m\nta9s4--,?is compact & picturesque gr\p ( hills1 ab\t twelve miles long & six miles broad1 & rea*+ a height ( #bgih feet 9 ,slieve ,don>d1 pres5ts a comp>atively simple geological /ructure1 s9ce x consi/s almo/ entirely ( granitic rocks :i* pi]ce1 ov]lie & und]lie ,upp] ,silurian grits & %ales4 ,s f> z reg>ds ! contact ( ^! rocks ) ! disrupt$ s$im5t>y =mations1 all t c be ass]t$ is t ! granite mu/ be lat] ?an at lea/ ! old] "p ( ! ,upp] ,silurian p]iod4 ,b = at lea/ two reasons1 ! eruptive rocks may be reg>d$ ) "s confid5ce z "p ( ! ,t]ti>y s]ies4 ,9 ! fir/ place1 !re is a /rong petrographical resemblance betwe5 ! ,m\rne ,m\nta9 granite & t ( ! ,isl& ( ,arran & ! granitic p>ts ( ! granophyre ( ! ,we/]n ,isles4 ,& ?is resemblance is s close z to furni% a cog5t argum5t 9 fav\r ( gr\p+ all ^! rocks toge!r z p>ts ( "o geologically contemporane\s s]ies4 ,9 ! second place1 ! ,m\rne ,m\nta9 granite abruptly cuts (f a l>ge numb] ( basic dykes :i*1 runn+ 9 a g5]al ,n4,n4,w4 direction1 may be look$ ^u z almo/ c]ta9ly memb]s ( ! ,t]ti>y sy/em ( protrusions4 ,! mann] 9 :i* ! granite ( ! di/rict behaves t[>ds c]ta9 deta*$ areas ( ,silurian /rata ) _! accompany+ dykes is "o ( ! mo/ a/oni%+ features 9 ! :ole assemblage ( intrusive rocks 9 ,brita94 ,z has be5 excell5tly %[n 9 ! ,geological ,survey ,map & sections by ,mr4 ,w4 ,a4 ,traill1 ! granite has c>ri$ up on its surface broad cakes ( v]tical ,silurian /rata1 toge!r ) all _! network ( dykes4#dah ,a cake ( ?is k9d1 f #ej to ab\t #bjj feet ?ick & ne>ly two miles broad1 has be5 bodily uplift$ f ! re/ ( ! mass & c>ri$ upw>d by ! granite1 s t ! truncat$ ends ( ! b$s ( grit & %ale ) _! sy/em ( dykes /& ^u a plat=m ( granite1 f :i* also num]\s ve9s p5etrate !m4 ,!re c be little d\bt t ! basic dykes ?us brok5 ?r\gh are p>ts ( ! great ,t]ti>y sy/em1 & if s1 ! granite :i* disrupts !m _c be old] ?an ,t]ti>y "t4 ,footnote #dah3 ,see ,%eets #fj1 #fa & #ga ( ! "o-in* map ( ! ,geological ,survey ( ,irel&1 & ,%eets #bb1 #bc & #bd ( ! ,horizontal ,sections4 ,! ,explanation to ^! ,%eets ( ! map 0 writt5 by ,pr(essor ,hull1 ,mr4 ,traill hav+ previ\sly retir$ f ! s]vice4 ,! ,m\rne ,m\nta9 area is n[ und]go+ critical revision by ,pr(4 ,sollas = ! ,geological ,survey1 & important additional mat]ial = ! elucidation ( ?is di/rict may be expect$ f him4 ,besides ! old] basic dykes disrupt$ by ! granite1 a y\ng] b mu* less abundant s]ies trav]ses t rock1 & also foll[s a g5]al nor?-we/]ly direction4 ,^! lat] dykes 9 "s cases cross m acid dykes :i* h ris5 ?r\gh ! granite4 ,!re is no trace ( any sup]ficial dis*>ge f ! ,m\rne ,m\nta9 area4 ,b f ! analogy ( o!r di/ricts we may easily conceive t ! granite repres5ts ! und]gr\nd p>ts ( volcanic mat]ial :i* has n[ be5 entirely remov$4 b4 ,slieve ,foye & ,b>navave ,di/rict4--,?is area embraces ! m\nta9\s gr\nd ly+ betwe5 ,c>l+=d ,l\gh & ,dundalk ,bay1 & culm9at+ 9 ,slieve ,foye 7#aice feet74 ,x measures r\ghly ab\t six miles 9 extreme l5g? & f\r miles 9 bread?4 ,! rem>kable assemblage ( basic & acid mat]ials 9 ?is area has receiv$ consid]able att5tion f geologi/s4 ,! relative ord] ( ! two gr\ps ( rocks 0 fir/ cle>ly recogniz$ by ,griffi?1 :o %[$ t ! granite 7granophyre7 is intrud$ into ! gabbro4#dai ,pr(essor ,haughton subsequ5tly confirm$ ?is obs]vation1 & prov$ ! po/-,c>bonif]\s date ( ! intrusive mat]ials1 :i* he comp>$ ) ^? ( ,skye4#dbj ,! g5]al di/ribution ( ! rocks 0 trac$ out 9 "s detail by ! ,geological ,survey1 & describ$ 9 ! (ficial ,memoirs4#dba ,m rec5tly ! di/rict has be5 exam9$ by ,pr(essor ,sollas1 :o1 br++ ! photographic cam]a & ! microscope to ! aid ( field-geology1 has elucidat$ ! /ructure & relations ( ! rocks1 & has obta9$ abundant evid5ce t ! acid & basic rocks ma9ta9 !re ! same relative ord] z among ! ,inn] ,hebrides4#dbb ,footnote #dai3 ,j\rn4 ,geol4 ,soc4 ,irel& 7#ahdc71 p4 #aac4 ,footnote #dbj3 ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xii4 7#ahef71 p4 #aga2 xiv4 p4 #cjj2 & ,j\rn4 ,geol4 ,soc4 ,irel& 7#ahgf71 p4 #ia4 ,footnote #dba3 ,%eet #ga ( ! ,geol4 ,surv4 ,irel&1 & accompany+ ,explanation4 ,^! 7 ! "w ( ,mr4 ,w4 ,a4 ,traill4 ,footnote #dbb3 ,trans4 ,roy4 ,iri% ,acad4 vol4 xxx4 7#ahid71 p4 #dgg4 ,?is is "p i4 ( :at is int5d$ to be a s]ies ( pap]s4 ,"o ( ! fir/ features 9 ?is tract ( c\ntry to arre/ ! eye ( ! geologi/ is ! situation ( ?is c5tre ( protrusion & t ( ,slieve ,gullion along a nor?-we/ l9e1 co9cid5t ) ! g5]al direction ( ! num]\s basic dykes ( ! region4 ,:e!r or n ! successive intrusions took place contemporane\sly 9 ! two areas1 !y h foll[$ ea* o!r 9 ! same ord]4 ,9 ! ,b>navave di/rict ! igne\s rocks occupy an area ( ab\t #bj squ>e miles4 ,!y consi/ ( a c5tral & *ief mass compos$ ( acid mat]ials1 :i* h ris5 ?r\gh ! basic rocks n[ f\nd z an int]rupt$ r+ r\nd !m4 ,9 8 m rec5t exam9ation1 ,pr(4 ,sollas has devot$ special att5tion to ! influ5ce ( ! solv5t action ( ! acid magma ^u ! basic rocks & ^u its own composition & /ructure4 ,besides confirm+ ! "w ( previ\s obs]v]s z to ! ord] ( appe>ance ( ! two k9ds ( mat]ial1 he has obta9$ evid5ce t ! gabbro _h n only completely solidifi$1 b 0 trav]s$ by contraction-jo9ts1 possibly ev5 fractur$ by e>?-movem5ts1 be=e ! injection ( ! granophyric mat]ial4 ,he f\nd t ?is mat]ial1 l t ( ! ,inn] ,hebrides & ,/4 ,kilda1 mu/ h be5 9 a /ate ( great fluidity at ! "t ( its intrusion1 & made its way into ! m9ute/ cracks & crevices4 ,9 obs]v+ ! solv5t action ( ! granophyre1 he asc]ta9$ t ?is action took place ev5 9 comp>atively n>r[ dykes1 :i* probably consolidat$ at no great dep? b5ea? ! surface4#dbc ,footnote #dbc3 ,op4 cit4 c4 ,! ,slieve ,gullion ,di/rict4--,?is area is sep>at$ f t j describ$ by a n>r[ /rip ( ,silurian /rata1 s t its isolation z a sep>ate igne\s di/rict is complete4 ,x w be obs]v$ f ! map to cont9ue ! same nor?-we/]ly l9e z ! ,slieve ,foye tract1 ! two toge!r runn+ 9 t direction = a di/ance ( "s #af miles4 ,x is int]e/+ to note ! adoption ( ?is pr$om9ant nor?-we/]ly tr5d ev5 by eruptive masses :i* 7 ma9ly ( acid mat]ial4 ,?is di/rict measures ab\t t5 miles 9 l5g? by f "o to five miles 9 bread?4 ,! rocks are1 on ! :ole1 simil> to ^? 9 ! area s\? ( ,c>l+=d ,l\gh1 & be> ! same relation to ea* o!r1 ! acid be+ intrusive 9 ! basic s]ies4 ,x is wor?y ( rem>k t ! ,t]ti>y eruptive rocks h made _! appe>ance 9 ! mid/ ( ! old] granite ( ,newry4 ,?is granite has be5 already allud$ to z disrupt+ ,upp] ,silurian /rata1 & be+ probably ( ! age ( ! ,l[] ,old ,r$ ,s&/one 7vol4 i4 p4 #bij74 ,9 long subsequ5t ages1 aft] protract$ d5udation1 dur+ :i* its cov] ( ,silurian & ,c>bonif]\s =mations 0 /ripp$ (f & x 0 laid b>e1 x 0 brok5 ?r\gh by ! :ole s]ies ( basic & acid protrusions ( ,slieve ,gullion4 ,?is di/rict is portray$ on ,%eets #ei1 #fj1 #gj & #ga ( ! ,geological ,survey ( ,irel&1 :i* %[ a c5tral core ( basic & acid mat]ial pi]c+ ! ,newry granite4#dbd ,r\nd ?is core & t\*+ x at its nor?-we/]n & s\?-ea/]n end1 b else:]e sep>at$ f x by a space ( sev]al miles1 runs a curi\sly cont9u\s b& ( igne\s mat]ial :i* is m>k$ z qu>tzif]\s porphyry & fel/one-porphyry on ! ,survey maps4 ,footnote #dbd3 ,! gr\nd 0 *iefly mapp$ & describ$ by ,mr4 ,joseph ,nolan & ,mr4 ,f4 ,w4 ,egan4 ,! s\?-we/]n portion ( ?is elliptical r+ possesses a peculi> int]e/ f its includ+ c]ta9 rem>kable masses ( breccia or agglom]ate4 ,^! rocks h be5 mapp$ by ,mr4 ,nolan1 & are describ$ by him 9 ! (ficial ,explanation1 b 9 m detail 9 two sep>ate pap]s4#dbe ,hav+ _h an opportunity ( pay+ a brief visit to ! gr\nd1 ,i c confirm ! g5]al accuracy ( 8 mapp+ & description1 & am able to add a few fur!r p>ticul>s to ! facts enum]at$ by him4 ,footnote #dbe3 ,%eet #gj ( ! ,geol4 ,surv4 ,map ( ,irel& & ,explanation !reto2 also ,j\rn4 ,roy4 ,geol4 ,soc4 ,irel&1 vol4 iv4 7#ahgg71 p4 #bcc2 ,geol4 ,mag4 #ahgh4 ,! tract ( gr\nd :]e ^! agglom]ates appe> =ms a prom95t ridge :i* rises sev]al hundr$ feet above ! l[] c\ntry on ei!r side1 & ext5ds 9 a ,w4,n4,w4 direction = ab\t sev5 miles1 ne>ly along ! l9e ( junction betwe5 ! ,newry granite & ! ,silurian /rata4 ,! ridge has a bread? v>y+ f a few hundr$ y>ds to upw>ds ( a mile4 ,x is sep>at$ f ! ma9 igne\s mass ( ! ,slieve ,gullion area by an int]v5+ /rip ( l[] gr\nd f ?ree-qu>t]s ( a mile to ab\t a mile & a half 9 wid?1 :i* is occupi$ by ! ,newry granite4 ,at ! nor?-we/ end ( ! ridge ! new] eruptive rocks lie )9 ! area ( t granite1 :ile at ! s\?-ea/ end !y rise entirely among/ ! ,silurian /rata4 ,beg9n+ at ! s\?-ea/]n extremity1 we f9d ! agglom]ate occupy+ sev]al deta*$ em95ces & surr\nd$ by alt]$ ,silurian grits & %ales4 ,fur!r we/ ! rock occurs 9 l>g] & m cont9u\s masses1 appe>+ at int]vals1 especially along ! s\!rn bord]s ( ! qu>tz-porphyry :i* =ms by mu* ! great] "p ( ! ridge4 ,actual junctions ( ! agglom]ate ) ! old] rocks ar\nd seem to be seldom visible4 ,i f\nd "o1 h[ev]1 above ! gamekeep]'s h\se on ! s\!rn flanks ( ! hill call$ ,tievecrom4 ,! ,upp] ,silurian grits & %ales1 9 a mu* indurat$ & %att]$ condition1 are !re traceable = sev]al hundr$ feet up ! slope1 until !y are abruptly cut (f by ! agglom]ate4 ,! l9e ( sep>ation appe>s to be ne>ly v]tical1 ! truncat$ ends ( ! /rata be+ wrapp$ r\nd by ! mass ( fragm5tal mat]ial4 ,! mo/ rem>kable features ( ?is agglom]ate1 :i* has be5 well describ$ by ,mr4 ,nolan1 are ! notable abs5ce ( truly volcanic /ones 9 x1 & ! d]ivation ( its mat]ials f ! rocks ar\nd x4 ,i f\nd only "o piece ( amygdaloid1 b n a s+le lump ( slag1 no bombs1 no brok5 fragm5ts ( lava-cru/s1 & no f9e volcanic du/ or enclos$ lapilli4 ,! rock may be said to consi/ entirely ( fragm5ts ( ,silurian grits & %ales :]e x lies among ^! /rata1 & ( granite :]e x comes ?r\gh t rock4 ,blocks ( ^! mat]ials1 ( all sizes up to two feet 9 bread?1 are confus$ly pil$ toge!r 9 a matrix made ( comm9ut$ debris ( ! same +r$i5ts4 ,! agglom]ate on ! ridge ( ,c>rickbroad has no def9ite b\nd>y1 b seems to graduate into an &esitic rock1 & !n into a qu>tz-felsite or rhyolite4 ,?is app>5t gradation is "o ( ! mo/ s+ul> features ( ! ridge4 ,! &esite resembles "s ( ! porphyrites ( ! ,old ,r$ ,s&/one4 ,x is close-gra9$1 ) abundant m9ute felsp>-la?s1 & num]\s l>ge porphyritic felsp>s1 :i* latt] are sometimes aggregat$ 9 pat*es1 z 9 ! old porphyries ( ,portra9e1 ,lambay ,isl& & ! ,*air ( ,kild>e4 ,?is rock has und\bt$ly be5 erupt$ at ! "t ( ! =mation ( ! agglom]ate1 or at lea/ be=e ! loose mat]ials 7 compact$ toge!r2 = x is full ( sep>ate /ones ( ! same mat]ials1 & becomes s *>g$ ) !m z to become itself a k9d ( agglom]ate1 ) a small proportion ( &esitic matrix cem5t+ ! blocks4 ,a ?9 slice prep>$ f "o ( ! specim5s obta9$ by me f ?is hill has be5 /udi$ by ,mr4 ,watts1 :o reports t ! f9e-gra9$ &esitic matrix 9 :i* ! /ones are imb$d$ has (t5 be5 inject$ into _! m9ute fissures1 & t ! m9ute fragm5ts enclos$ 9 ?is matrix consi/ "h ( a tra*yte-l porphyry1 felsite1 &esites1 basalts ( v>i\s degrees ( f95ess & oliv9e-basalt1 toge!r ) isolat$ gra9s ( felsp>1 su* z might h be5 d]iv$ f ! break+ up ( "s ( ^! fragm5ts4 ,we/w>d f ,c>rickbroad1 ! *ief eruptive rock is a d>k1 sometimes ne>ly velvet-black1 fl9ty1 occasionally almo/ res9\s1 qu>tz-porphyry or rhyolite1 ) abundant qu>tz & l>ge felsp>s & occasional well-m>k$ fl[-/ructure4 ,?is mat]ial1 ne> ! mu* small] protrusion ( &esite1 is curi\sly mix$ up ) t rock1 z if ! two _h come up toge!r4 ,sometimes !y seem to pass into ea* o!r1 at lea/ ! sep>ation betwe5 !m _c be %>ply drawn4 ,!re c be little d\bt1 h[ev]1 t ! acid magma cont9u$ to asc5d aft] ! o!r1 = x s5ds ve9s & /r+s into ! m basic mat]ial1 & encloses blocks ( x4 ,?is ?or\ghly acid porphyry plays ! same "p z ! &esite 9 reg>d to ! /ones ( ! agglom]ate4 ,?r\gh\t its :ole ext5t1 x is f\nd to enclose ^! /ones1 :i* "h & !re become s num]\s z to =m ! ma9 bulk ( ! mass1 leav+ only a limit$ am\nt ( qu>tz-porphyry 7rhyolite7 matrix to b9d ! :ole into an exce$+ly compact v>iety ( breccia4 ,occasionally ! acid rock cuts ?r\gh ! ord9>y cla/ic agglom]ate1 z may be well se5 on ! s\!rn face ( ,tievecrom4 ,a specim5 ( ?is porphyry ) its enclos$ fragm5ts1 :i* 0 collect$ by me f above ! old t[] at ,gl5dovey1 ,c>rickbroad1 has be5 slic$ & exam9$ by ,mr4 ,watts "u ! microscope1 & is ?us describ$ by him3 ,! l>ge fragm5t 9 ?is slide consi/s ( ophitic oliv9e-dol]ite full ( l>ge ph5ocry/s ( oliv9e4 ,x is brok5 up & p5etrat$ by ve9s ( qu>tz-porphyry1 ri* 9 qu>tz1 :i* exhibits a beautiful fl[-/ructure4 ,! felsp>s & augite ( ! dol]ite d n appe> to h suff]$ mu* alt]ation at ! m>g9 ( ! fragm5t1 b ! oliv9es are mu* s]p5t9iz$1 ! s]p5t9e pass+ into a bord] ( act9olite :i* runs 9 ve9s into ! neighb\r+ rock & ev5 passes out into ! qu>tz-porphyry at ! junction1 impregnat+ x ) act9olite & *lorite = "s di/ance4 ,a few p>ticles ( basalt also occur & a portion ( a granite-fragm5t comes into ! slide1 f ! edge ( :i* a piece ( biotite has float$ (f into ! qu>tz-porphyry4 ,! ess5tially non-volcanic mat]ial ( ! agglom]ate %[s1 z ,mr4 ,nolan po9t$ out1 t x 0 produc$ by ri=m explosions1 :i* blew out ! ,silurian /rata & granite 9 fragm5ts & du/4 ,^! dis*>ges probably took place ei!r f a s]ies ( v5ts plac$ along a l9e ( fissure runn+ 9 a nor?-we/]ly l9e1 or directly f ! op5 fissure itself4 ,possibly bo? ( ^! *annels ( escape 7 9 use2 deta*$ v5ts appe>+ at ! ea/ end & a m cont9u\s dis*>ge f ! fissure fur!r we/4 ,aft] ! e>lie/ explosions _h ?r[n out a l>ge am\nt ( granitic & ,silurian detritus1 &esitic lava rose 9 ! fissure1 & solidify+ !re enclos$ a great deal ( ! loose fragm5t>y mat]ial t fell back into ! *asm4 ,subsequ5tly1 & on a m ext5sive scale1 a mu* m acid magma asc5d$ f bel[1 likewise involv+ & c>ry+ up a va/ quantity ( loose /ones1 among :i* are pieces ( basalt & dol]ite4 ,no evid5ce rema9s z to ! ext5t ( ! mat]ial dis*>g$ ov] ! surface f ?is fissure4 ,d5udation has remov$ all ! surr\nd+ fragm5tal %eets z well z any lava t may h fl[$ out ^u or become int]calat$ among !m4 ,!re rema9s n[ only ! cores ( ! little necks at ! ea/ end1 & ! indurat$ agglom]ate & lava t consolidat$ along ! m\? ( ! fissure or v5ts4 ,?is is ! only example ( su* a l9e ( fissure-eruption :i* has yet be5 met ) 9 ! ,briti% ,isles4 ,its connection ) ! eruptive masses ( ,slieve ,gullion & ,c>l+=d l9ks x ) ! ,t]ti>y volcanic s]ies4 ,b no evid5ce appe>s to rema9 reg>d+ ! epo* 9 ! long volcanic p]iod :5 ! eruptions f x took place4 ,!y may possibly date back to ! "t ( ! plateau-basalts2 b ! abundant acid magma1 :i* con/itutes "o ( _! di/+ui%+ *>act]i/ics1 sugge/s t !y m probably belong to ! lat] "t :5 ! ma9 protrusions ( acid mat]ial took place4 ,!y sugge/ t coeval ) ! uprise ( ! great domes ( ,slieve ,gullion1 ,c>l+=d & ! ,m\rne ,m\nta9s !re may h be5 _m sup]ficial eruptions ( :i*1 aft] prolong$ d5udation1 all trace has n[ be5 effac$4 #b4 ,! ,antrim ,region ,ref]5ce 0 made 9 ,*apt] xxxvii4 to ! occurr5ce ( rhyolitic conglom]ate & tuff betwe5 ! l[] & upp] s]ies ( basalts 9 ! ,antrim plateau1 & to ! evid5ce furni%$ by ^! detrital deposits ei!r t masses ( rhyolite appe>$ at ! surface1 or t rhyolitic a%es 7 dis*>g$ f volcanic v5ts 9 ! long int]val t elaps$ betwe5 ! two gr\ps ( basalt4 ,! fur!r consid]ation ( ?is "q1 & an acc\nt ( ! rhyolite bosses1 7 res]v$ = ! pres5t *apt]1 t !y might be tak5 9 connection ) ! o!r acid eruptions ( ,t]ti>y "t 9 ,brita94#dbf ,footnote #dbf3 ,= an e>ly acc\nt ( ! ,antrim tra*ytic rocks1 see ,b]g]1 ,trans4 ,geol4 ,soc4 iii4 7#ahaf71 p4 #aij4 ,pr(essor ,hull has describ$ ! ,t>dree rock 9 ! ,explanation to ,%eets #ba1 #bh & #bi1 ,geol4 ,survey ( ,irel& 7#ahgf71 p4 #ag1 & has suppos$ x to be old] ?an ! basalts1 ref]r+ x to ! ,eoc5e p]iod 7,physical ,geology & ,geography ( ,irel&1 #bnd edit4 7#ahia71 pp4 #hg1 #ie74 ,duff9 7quot$ by ,mr4 ,k9ahan7 believ$ t ! tra*ytes occur at ! c5tre ( eruption1 & 7 probably p\r$ out at ! end ( ! outbur/4 ,du ,noy] also 7quot$ by ! same writ]7 ?\ght !m to be new] ?an ! plateau-basalts1 & to h lift$ up masses ( ^! rocks4 ,mr4 ,k9ahan himself 7,geology ( ,irel&1 p4 #agb7 has po9t$ to ! abs5ce ( any rhyolitic fragm5ts betwe5 ! basalts z an argum5t aga9/ ! suppos$ antiquity ( ! acid protrusions4 ,a petrographical acc\nt ( ! ,t>dree rock is giv5 by ,von ,lasaulx 9 ! pap] already cit$1 ,ts*]mak's ,m94 ,pet4 ,mit!il4 7#ahgh71 p4 #dab4 ,a m elaborate discussion ( ! petrography by ,pr(4 ,cole w be f\nd 9 ! ,memoir above ref]r$ to 7,sci5tif4 ,trans4 ,roy4 ,dubl9 ,soc4 vol4 vi4 #ahif71 & ! geological relations ( ! rocks are discuss$ by him 9 ano!r %ort] pap]1 ,geol4 ,mag4 7#ahie71 p4 #cjc4 ,see also ,mr4 ,m',h5ry on ! tra*ytic rocks ( ,antrim1 ,geol4 ,mag4 7#ahie71 p4 #bfj1 & ,proc4 ,geol4 ,assoc4 vol4 xiv4 7#ahie71 p4 #adj4 ,) "o exception1 all ! kn[n protrusions ( acid mat]ial 9 ! ,antrim area lie )9 ! limits ( ! basalt-plateau 7see ,map4 ,no4 ,,vii474 ,!y occur along a l9e at int]vals = a di/ance ( ab\t #ag miles1 f ,templepatrick to a po9t f\r miles nor? ( ,ballym5a4 ,x is wor?y ( rem>k t "h aga9 ! l9e ( protrusion has a nor?-we/ tr5d4 ,x n improbably indicates ! position ( a fissure up :i* ! acid mat]ial rose at v>i\s po9ts4 ,! petrography ( ! rocks has be5 frequ5tly discuss$4 ,!y include sev]al v>ieties ( rhyolite1 g5]ally r co>sely cry/all9e1 b sometimes becom+ compact1 & ev5 pass+ into d>k obsidian4 ,no und\bt$ tuff occurs associat$ ) !m 9 any ( ! exposures1 nor d ! rhyolites any:]e display /ructures t po9t to _! hav+ fl[$ out at ! surface4#dbg ,t ! masses n[ visible may h communicat$ ) ! surface is q conceivable1 b :at we n[ see appe>s 9 e case to be a subt]ranean & n a sup]ficial "p ( ! protrusion4 ,footnote #dbg3 ,at ,s&y ,braes an exposure is visible ( :at at fir/ might be ?\ght to be a volcanic conglom]ate1 b clos] exam9ation %[s ! rock to consi/ ( obsidian1 :i* decomposes into a clay1 leav+ r\nd %>ply-def9$ glassy cores enclos$ 9 ! decay$ mat]ial4 ,! b&$ rhyolites d n exhibit any k9d ( fl[-/ructure t may n be met ) 9 dykes & bosses4 ,nor h any satisfactory traces be5 f\nd ( vesicul> or pumice\s b&s su* z might m>k ! upp] surfaces ( true lava-/reams4 ,pr(essor ,cole has describ$ :at he calls ,! ,volcanoe ( ,t>dree 7,geol4 ,mag4 ,july #ahie74 ,if ! ,t>dree mass ev] 0 a volcano1 :i* is f> f improbable1 its sup]ficial ejections h long ago disappe>$4 ,at lea/1 aft] ! mo/ dilig5t se>*1 ,i h be5 unable to discov] any trace ( !m1 all t n[ rema9s appe>+ to me to be ! neck or core ( protrud$ mat]ial4 ,illu/ration3 ,fig4 #cgj4--;,intrusive rhyolite 9 ! ,l[] ,basalt gr\p ( ,antrim1 ,templepatrick4 #a #a1 ,*alk2 #b #b1 ,gravel2 #c #c1 ,b$d$ basalt2 #d #d1 ,rhyolite1 intrusive4 ,mo/ ( ! rhyolitic exposures are extremely limit$ 9 area--m]e little knobs1 sometimes ris+ 9 ! middle ( a bog1 & nev] =m+ conspicu\s features 9 ! l&scape4 ,! relation ( ^! rocks to ! basalts are g5]ally conceal$1 b ! isolation ( ! small rhyolitic pat*es leaves no d\bt t !y are intrusive z reg>ds ! surr\nd+ basalts4 ,?is relation is well se5 at ,templepatrick1 :]e x 0 fir/ obs]v$ by ,mr4 ,m',h5ry ( ! ,geological ,survey 7,fig4 #cgj74 ,! rhyolite !re =ms a sill :i* has be5 ?ru/ betwe5 ! basalts & ! gravel t und]lies !m1 ! basalts be+ b5t back & und]la9 by ! acid rock4#dbh ,footnote #dbh3 ,! progress ( qu>ry+ op]ations dur+ ! la/ eight ye>s has some:at de/roy$ ! section z expos$ 9 #ahhh4 ,b we n[ see t ! basalt has n only be5 b5t back b is und]la9 by ! acid rock4 ,! l>ge/ & mo/ int]e/+ ( ! ,antrim rhyolite tracts cov]s a space ( ab\t t5 squ>e miles 9 ! he>t ( ! basalt-plateau to ! nor?-ea/ ( ! t[n ( ,antrim4 ,x rises to ab\t #ajjj feet above ! sea1 & =ms a few featureless hills1 "s ( :i* are capp$ ) basalt4 ,! be/ kn[n localities 9 ?is tract are ,t>dree & ,c>ne>ny4 ,! rock is *iefly a some:at co>se-textur$ li?oidal rhyolite1 b includes also vitre\s portions4 ,illu/ration3 ,fig4 #cga4--,section across ! s\!rn slope ( ,c>ne>ny ,hill1 ,antrim4 a a a1 b$d$ basalts2 b1 rhyolite4 ,ow+ to ! cov] ( soil & turf1 ! junction ( ?is mass ) ! surr\nd+ basalts _c be s cle>ly se5 z 9 ! sections ( ! ,inn] ,hebrides1 & h5ce ! /ratigraphical relations ( ! two gr\ps are apt to be misund]/ood4 ,:at is actually se5 is repres5t$ 9 ,fig4 #cga4 ,! li?oidal rhyolite em]ges f und]nea? ! basalts :i* abut aga9/ its slop+ surface1 =m+ on ! nor? side ( ,c>ne>ny ,hill a /eep bank ab\t #aej feet above ! m g5tly incl9$ slope bel[4 ,! basalts consi/ ( successive ne>ly level %eets ( compact & amygdaloidal rock4 ,x is obvi\s t only two explanations ( ?is section are possible4 ,ei!r ! rhyolite 0 9 exi/5ce be=e ! basalts :i* fl[$ r\nd x & gradually cov]$ x1 or x has be5 erupt$ ?r\gh ^! rocks1 & is !re=e ( lat] date4 ,! =m] supposition has be5 ! m usually receiv$4 ,! rhyolite has be5 suppos$ to =m ! summit ( an anci5t volcanic dome1 p]haps ( ,eoc5e age1 :i* _h be5 worn d[n be=e ! outfl[ ( ! plateau-basalts "u :i* x 0 ev5tually entomb$4 ,_h ?is be5 ! true hi/ory ( ! locality1 x is inconceivable t ( a rock :i* decays s rapidly z ?is rhyolite1 & /rews its slopes ) su* abundance ( detritus1 n a s+le fragm5t %\ld occur betwe5 ! successive b$s ( basalt :i* are suppos$ to h surr\nd$ & buri$ x4 ,?\gh ! sev]al b$s ( basalt are well expos$ all r\nd1 ,i c\ld n1 on my fir/ visit1 f9d a trace ( any rhyolitic fragm5ts betwe5 !m1 nor _h ,mr4 ,symes1 :o mapp$ ! gr\nd 9 detail = ! ,geological ,survey1 be5 m successful4 ,i h s9ce made a second se>* ) ,mr4 ,m',h5ry1 b )\t detect+ a s+le pebble ( ! acid rock among ! basalts4 ,yet x is cle> f ! upp] surfaces ( "s ( ^! lavas t a consid]able int]val ( "t sep>at$ _! successive outfl[s1 s t !re 0 opportunity en\gh = ! scatt]+ ( rhyolite-debris _h any hill ( t rock exi/$ 9 ! vic9ity4 ,aga91 little m ?an a mile to ! ea/ ( ,c>ne>ny ,hill1 an outli] ( ! basalts =m+ ! prom95t height ( ! ,br[n ,dod lies ^u & is completely surr\nd$ by ! rhyolite1 :i* along ! ea/ side ( ! hill c be trac$ z x passes "u ! level %eets ( basalt4 ,! l9e ( junction asc5ds & desc5ds on t flank ( ! outli]1 s t successive fl[s ( basalt are truncat$ by ! acid rock4 ,b ,i c\ld f9d no rhyolitic debris betwe5 !m4 ,x appe>s to me1 !re=e1 t ! relations betwe5 ! two gr\ps ( rock 9 ?is area are simil> to ^? betwe5 ! granophyres & b$d$ basalts on ! s\? side ( ,lo* na ,keal 9 ,mull 7p4 #cif74 ,9 o!r words1 ! rhyolites h ris5 ?r\gh ! basalts1 & are !re=e y\ng] ?an ^! lavas4 ,?is conclusion is corroborat$ by ! actual pro(s ( ! intrusion ( rhyolite into ! basalts at ,templepatrick4 ,all ! kn[n rhyolitic masses 9 ,antrim are conf9$ to ! ,l[] gr\p ( basalts4#dbi ,& z !y trav]se "s ( its highe/ memb]s1 !y may be reg>d$ z c]ta9ly y\ng] ?an t gr\p4 ,mr4 ,m',h5ry1 :o fir/ indicat$ ?is relation1 sugge/$ t ! rhyolites 7 erupt$ 9 ! int]val betwe5 ! two basaltic s]ies1 & he connect$ ) _! eruption ! rhyolitic detritus f\nd 9 association ) ! iron-ore at s _m places 9 ,antrim4 ,x appe>s to me t ?is sugge/ion c>ries ) x mu* probability4 ,! rhyolitic conglom]ate ( ,gl5>m proves t1 9 ! long p]iod repres5t$ by ! iron-ore & its associat$ gr\p ( s$im5t>y deposits1 !re 7 masses ( rhyolite at ! surface1 ! wa/e ( :i* c\ld supply su* detritus4 ,! resemblance betwe5 ! mat]ial ( t conglom]ate & ! rhyolites n[ visible at ,t>dree & else:]e is s close t we _c d\bt t1 if n d]iv$ f "s ( ! kn[n rhyolitic protrusions1 ?is mat]ial c]ta9ly came f expos$ masses t _h ! same g5]al petrographic *>act]s4 ,footnote #dbi3 ,! only exception to ?is rule 0 believ$ to be t ( ! mass at ,esl]/[n1 f\r miles ea/ ( ,ballym5a1 :i*1 z orig9ally mapp$1 0 %[n z cross+ f ! ,l[] into ! ,upp] basalts4 ,mr4 ,m',h5ry1 h[ev]1 has rec5tly asc]ta9$ t ! acid rock is entirely re/rict$ to ! area ( ! old] gr\p4 ,:ile ! rhyolite pebbles 9 ! ,gl5>m conglom]ate are di/9ctly r\nd$ & wat]-worn1 %[+ t "s prom95ces ( acid rock 7 und]go+ active d5udation at ! "t :5 ?is conglom]ate 0 laid d[n1 ! f9] rhyolitic detritus 9 ! tuffs ( ,ballypallidy r sugge/s ! actual dis*>ge ( rhyolitic a%es dur+ ! same p]iod4 ,b x w\ld appe> t ! sup]ficial outbur/s ( rhyolitic mat]ial1 :e!r 9 ! =m ( lava or ( tuff1 7 only ( trifl+ ext5t1 or else t ! int]val betwe5 ! eruption ( ! two basalt-gr\ps 0 s prolong$ t any su* sup]ficial mat]ial 0 !n remov$ by d5udation4 ,! v>ieties ( li?ological "* to be met ) among ! acid protrusions ( ,antrim sugge/s a succession ( uprises ( rhyolites diff]+ f ea* o!r m or less 9 composition & /ructure4 ,un=tunately ! gr\nd is g5]ally s cov]$ ) sup]ficial accumulations1 & ! exposures ( rock are s poor & limit$1 t no sequ5ce has yet be5 det]m9$ among ! sev]al k9ds ( acid rock4 ,! only locality :]e ,i h obs]v$ cle> evid5ce ( su* a sequ5ce is on ! old qu>ries half a mile we/ ( ,%ank]burn ,bridge1 & ?ree miles nor?-we/ ( ,dromore1 ,c\nty ,d[n4 ,a small boss ( rhyolite !re rises ?r\gh ! ,silurian /rata4 ,x consi/s p>tly ( a co>se-gra9$ li?oidal rhyolite1 ) l>ge smoky qu>tzes & felsp>s1 & p>tly ( a mu* f9] textur$ v>iety4 ,! latt]1 on ! s\? side ( ! small brook :i* sep>ates ! qu>ries1 c be se5 to asc5d v]tically ?r\gh ! co>se-gra9$ rock into :i* x s5ds a project+ ve94 ,its m>g9 %[s a /reaky fl[-/ructure p>allel ) its v]tical wall & is 9 places sph]ulitic4 ,"h ! clos]-gra9$ rock is c]ta9ly lat] ?an ! re/ ( ! mass4 ,,*apt] ,,xlviii ,,! ,,acid ,,sills1 ,,dykes ,,& ,,ve9s i4 ,,! ,,sills ,n only h ! acid rocks be5 protrud$ 9 small & l>ge bosses1 !y h also be5 inject$ z sills betwe5 ! b$d+-planes ( /ratifi$ rocks1 betwe5 ! surfaces ( ! basalt-b$s1 & betwe5 ! bottom ( ! plateau-basalts or ( ! gabbros & ! plat=m ( old] rock on :i* ! volcanic s]ies has be5 pil$ up4 ,e gradation ( size may be obs]v$1 f m]e p>t+s n m ?an an in* or two 9 ?ickness1 up to massive %eets1 :i* n[1 ow+ to ! removal ( _! orig9al cov]+ ( rock by d5udation1 =m m9or gr\ps & ranges ( hills4 ,:]e ! %eets are num]\s1 !y are usually small 9 size2 :]e1 on ! o!r h&1 !y are few 9 numb]1 !y rea* _! greate/ dim5sions4 ,x is n always possible to discrim9ate betwe5 bosses & l>ge irregul> sills4 ,a good illu/ration ( ! connection betwe5 ^! two =ms ( intrusion w be cit$ f ! isl& ( ,raasay1 :]e a widespread intrusive %eet is 9 "p connect$ ) a true boss4 ,9 ,mull1 sills ( acid eruptive rocks are pr(usely abundant ?r\gh\t ! c5tral m\nta9\s tract betwe5 ,lo* na ,keal & ,lo* ,spelve4 ,if we asc5d ! slopes f ! ,s\nd ( ,mull1 = in/ance1 we h n gone f> be=e "s ( ^! %eets make _! appe>ance4 ,!y are usually dull granul> qu>tz-porphyries1 or granophyres1 (t5 only two or ?ree feet 9 ?ickness1 & int]pos$ betwe5 ! b$s ( basalt t =m ! mass ( ! hills4 ,along ! cre/ ( ! ridge t /ret*es ?r\gh ,be9n ,*reaga* ,mhor to ,ma9nir nam ,fiadh !y take a prom95t place among ! l$ges ( basalt1 basalt-conglom]ate & dol]ite4 ,! l>ge/ %eet 9 ,mull is probably t :i* has ?ru/ itself betwe5 ! base ( ! basalts & ! und]ly+ ,jurassic /rata & cry/all9e-s*i/s on ! %ore ( ! ,s\nd ( ,mull at ,craignure4 ,! porphyry ( ?is %eet is ref]r$ to by ,pr(essor ,zirkel z only a f9]-gra9$ v>iety ( ! same qu>tzif]\s rock1 ) hornbl5de & or?oclase cry/als1 :i* 9 ,skye breaks ?r\gh ! ,lias4#dcj ,on ! s\? coa/ also1 at ! base ( ! ?ick basalt s]ies1 simil> porphyries h be5 inject$ into ! und]ly+ /rata2 & "u ! great gabbro mass ( ,b5 ,buy simil> protrusions occur4 ,b z we retire f ! m\nta9\s tract into ! undi/urb$ basalts ( ! plateau1 ^! acid int]calations gradually disappe>4 ,footnote #dcj3 ,zeits*4 ,deuts*4 ,geol4 ,gesells*4 xxiii4 p4 #ed4 ,9 ! isl&s ( ,eigg & ,rum1 excell5t examples occur ( ! t5d5cy :i* ! %eets ( porphyry or granophyre manife/ to appe> at or ab\t ! base ( ! b$d$ basalts4 ,i h already allud$ to ! boss or %eet at ! nor? end ( ! =m] isl&4 ,a /ill m /rik+ illu/ration occurs 9 ,rum4 ,all along ! base ( ! great mass ( gabbro1 protrusions ( v>i\s k9ds ( acid rock h tak5 place4 ,! great mass ( ,orval1 already describ$1 is "o ( ^!4 ,bel[ ,b>keval & r\nd ! foot ( ! hills to ! s\?-ea/ ( t em95ce an int]rupt$ b& ( qu>tz-porphyry may be trac$1 f :i* ve9s proce$ into ! gabbros & dol]ites4 ,b x is 9 ,skye & ,raasay t ! intrusive %eets ( ! acid gr\p ( rocks rea* _! *ief developm5t4 ,!y h be5 mo/ abundantly inject$ und]nea? ! b$d$ basalts1 p>ticul>ly among ! ,jurassic /rata4 ,a b& or belt ( !m1 ?\gh n cont9u\s1 c be trac$ r\nd ! ea/ side ( ! ma9 body ( granophyre1 at a di/ance ( f a mile & a half to ab\t ?ree miles4 ,beg9n+ ne> ! po9t ( ,suisni%1 ?is belt curves ?r\gh ! hilly gr\nd = "s five miles1 until x dies out on ! slopes above ,skulamus4 ,x may be f\nd aga9 on ! we/ side ( ! ridge ( ,be9n ,su>dal1 & on ! moors above ,corry1 till x rea*es ! %ore at ! ,rudh' an ,eireanni* 7,iri%man's ,po9t74 ,x skirts ! we/ side ( ,scalpa ,isl&1 & runs = "s miles ?r\gh ,raasay4 ,ano!r s]ies ( sills occurs bel[ ! basalts & gabbros 9 ! ,blav5 gr\p ( hills4 ,ov] a l>ge "p ( _! c\rse1 ! rocks ( ! ea/]n belt re/ 9 great ov]ly+ %eets ^u ! ,jurassic /rata1 :i* may almo/ ev]y:]e be se5 dipp+ "u !m4 ,f ! analogy ( o!r di/ricts1 we may1 ,i ?9k1 inf] t ! position ( ^! sills "h po9ts to _! hav+ be5 intrud$ at ! base ( ! plateau-basalts :i* h s9ce be5 remov$ f almo/ ! :ole tract4 ,=tunately1 a portion ( ! basalts rema9s 9 ,raasay1 & enables u to connect t isl& ) ! great plateau ( ,skye ( :i* x once =m$ a "p4 ,!re c be no d\bt t ! basalts ( ! ,dn ,caan ridge once ext5d$ we/w>ds across ! tract ( granophyre :i* n[ =ms mo/ ( ! surface betwe5 t ridge & ! ,s\nd ( ,raasay4 ,a ?9 %eet ( qu>tz-porphyry1 int]pos$ among ! ,oolitic /rata1 may be se5 a little inl& f ! top ( ! great ea/]n cliff & bel[ ! position ( ! b$d$ basalts4 ,! great %eet1 or r s]ies ( %eets1 :i* /ret*es nor?-ea/w>ds f ,suisni% at ! m\? ( ,lo* ,ei%ort 9 ,skye1 consi/s ( a rock :i* = ! mo/ "p may readily be di/+ui%$ 9 ! field f ! granitoid mat]ial ( ! bosses4 ,x appe>s to ! nak$ eye to be a r close-gra9$ or f9ely cry/all9e-granul> qu>tz-porphyry1 ) scatt]$ blebs or bi-pyramidal cry/als ( qu>tz & cry/als ( or?oclase4 ,at ! contact ) adjac5t rocks1 ! texture becomes m felsitic1 sometimes di/9ctly sph]ulitic 7we/ side ( ,c>n ,na?ragh1 next ,lias %ale74 ,"u ! microscope ! rock is se5 to be a f9e-gra9$ granophyric porphyry or porphyritic granophyre4 ,x caps ,c>n ,de>g 7#fcf feet7 above ,suisni%1 :]e x cov]s a space ( ne>ly a squ>e mile1 & rea*es at its ea/]n extremity 7,be9n ,bhuidhe71 a height ( #ijh feet above ! sea 7,fig4 #bdi74 ,?is rock re/s ^u a sill ( dol]ite1 & is app>5tly split up by x4 ,b1 z ,i h already /at$1 ! basic rock is probably ! old] ( ! two1 & ! granophyre seems to h w$g$ itself betwe5 two e>li] dol]itic %eets4 ,to ! nor?-we/ ( ,c>n ,de>g1 above ! nor!rn end ( ! cr(ts ( ,suisni%1 ! same sill1 or "o occupy+ a simil> position1 crops out betwe5 masses ( granophyre1 & is int]sect$ by n>r[ ve9s f t rock4 ,?\gh sev]$ by d5udation1 ! l>ge %eets ( granophyre to ! ea/ ( ,be9n ,bhuidhe are no d\bt cont9uations ( ! ,c>n ,de>g mass1 or at lea/ occupy a simil> position4 ,t !y are completely uncon=mable to ! ,jurassic /rata is %[n by ! fact1 t :ile at ,suisni% !y lie on s&/ones :i* mu/ be fully #ajjj feet above ! bottom ( ! ,lias1 only two miles to ! ea/ !y are f\nd re/+ on ! v basem5t lime/ones1 )9 a few y>ds f ! und]ly+ qu>tzite & ,torridon s&/one4 ,i d n ?9k t ?is transgression c be acc\nt$ = by intrusion obliquely across ! /ratification4 ,i reg>d x z aris+ f ! eruptive rock hav+ =c$ its way betwe5 ! bottom ( ! n[ vani%$ basalt-plateau & ! d5ud$ surface ( ,jurassic rocks1 ov] :i* ! basalts 7 p\r$4 ,! plat=m und]nea? ^! granophyre sills ?us repres5ts1 9 my op9ion1 ! t]re/rial surface be=e ! beg9n+ ( ! volcanic p]iod4 ,b !re is abundant pro( t ?\gh ! intrud$ granophyre sills foll[$ g5]ally ?is plane ( sep>ation1 !y did n rigidly adh]e to x1 b burr[$1 z x 71 along l[] horizons4 ,?us on ! s\?-ea/ front ( ,be9n a' ,*irn1 :i* =ms s f9e an esc>pm5t above ! valley ( ,hea/1 ! base ( ! granophyre1 aft] creep+ upw>d across successive b$s ( lime/one1 s5ds out a n>r[ tongue into ^! /rata1 & cont9ues its c\rse a little high] up 9 ! ,lias4 ,! same rock1 aft] spread+ out into ! broad flat tablel& ( ,be9n a' ,*irn 7#ihc feet71 rapidly contracts nor?-ea/w>ds into a n>r[ /rip :i* =ms ! cre/ ( ! ridge1 & at once sugge/s a mu*-wea!r$ lava-/ream4 ,! resemblance to a c\le is height5$ by ! curi\s ?9n+ (f ( ! rocks :]e ! two /reams em]ge f ! ,hea/ lo*s2 x looks z if ! igne\s mass 7 a m]e sup]ficial ridge :i* _h be5 cut d[n by erosion1 s z to expose ! %ales b5ea? x4 ,b t ! granophyre is really a sill becomes abundantly cle> at its ea/]n end1 :]e we f9d t x consi/s ( two sep>ate %eets ) int]v5+ ,liassic %ales4 ,! /ructure ( ?is int]e/+ locality is %[n 9 ,fig4 #cgb4 ,9 ?is in/ance also1 !re is evid5ce t ! acid sills are y\ng] ?an ! basic1 = ! upp] %eet ( granophyre s5ds up into ! ov]ly+ d>k basaltic rock n>r[ v]tical felsitic ve9s1 a qu>t] ( an in* to an in* 9 wid?1 :i* be+ m durable1 /& out above ! decomposable surface ( ! conta9+ rock1 & %[ _! qu>tz-blebs & felsp> cry/als on ! wea!r$ surface4 ,p]haps ! mo/ /rik+ feature ( ! granophyre sills ( ,skye is _! g5]al association ) ?9n] basic intrusive %eets betwe5 :i* !y h ins9uat$ !mselves4 ,?is *>act]i/ic /ructure1 po9t$ out by me 9 #ahhh1 has rec5tly be5 m m9utely mapp$ 9 ! progress ( ! ,geological ,survey4 ,mr4 ,h>k] has f\nd ! typical arrangem5t to be ! occurr5ce ( a ?ick sill ( granophyre int]pos$ betwe5 two sills ( basalt1 ea* ( :i* is usually n m ?an six or eight feet ?ick4 ,:]e ! granophyre has be5 intrud$ indep5d5tly among ! ,lias =mations1 x does n assume ! regul>ity & p]si/5ce :i* m>k x :]e x has foll[$ ! c\rse ( basic sills4 ,illu/ration3 ,fig4 #cgb4--,section across ! ,granophyre ,sills at ,lo* a' ,mhullai*1 above ,skulamus1 ,skye4 a1 ,jurassic s&/ones & %ales2 b1 ,jurassic d>k br[n s&y %ales2 c1 sills ( basalt1 "s b&s highly cellul>2 c1 basalt-sill ) ve9s ( felsite ris+ into x f ! granophyre bel[2 d d1 intrusive %eets or sills ( granophyre4 ,! acid rock1 ,mr4 ,h>k] obs]ves1 is inv>iably ! lat] intrusion1 = x s5ds n>r[ ve9s into ! basalts1 metamorphos+ !m to "s ext5t & frequ5tly enclos+ fragm5ts ( !m4 ,^! fragm5ts are always r\nd$ by corrosion1 & %[ v>i\s /ages ( dissolution d[n to m]e d>k] pat*es z se5 by ! nak$ eye4 ,su* inclusions & pat*es are f\nd 9 ! m>g9al "p ( a granophyre1 :]e no cont9u\s basalt occurs1 b :]e ! acid magma has evid5tly 9 places completely de/roy$ ! e>li] basic %eets betwe5 :i* x 0 =c$4 ,x seems probable t 9 all cases a c]ta9 am\nt ( solution ( ! basalt by ! granophyre magma took place at _! contact1 facilitat+ ! injection ( ! lat] intrusion & acc\nt+ = its p]si/5t *oice ( ! contact-plane ( two basalt-sills z ! surface (f]+ lea/ resi/ance to its injection4 ,^! obs]vations ?r[ fre% light on ! rem>kable orig9al regul>ity & p]si/5ce ( ! basic sills4 ,:]e "o ( ^! sills disappe>s above or bel[ a granophyre %eet its probable =m] pres5ce is (t5 indicat$ by corrod$ fragm5ts ( ! basic 9 ! acid rock4 ,mr4 ,h>k] rem>ks t ! acid magma seems to h be5 9 itself less adapt$ ?an ! basic to foll[ accurately a def9ite horizon & to ma9ta9 a uni=m ?ickness 9 its intrud$ %eets1 b c\ld d bo? :5 guid$ by a pre-exi/+ basalt-sill1 or especially :5 ins9uat$ betwe5 contigu\s basalt-sills4 ,! corrosive action ( ! acid magma on ! surface ( ! basalt1 :i* enabl$ x to =ce its way m readily betwe5 ! basic sills1 might proce$ s f> z p>tially or :olly to de/roy ^! sills4 ,?is solv5t action may s]ve to expla9 "s ( ! irregul>ities ( ! granophyre intrusions4 ,accord+ to ! same obs]v]1 su* irregul>ities are f\nd :]e ! granophyre %eet & its encas+ basalt-sills are n co-ext5sive1 or aga9 :]e ! two basalt-sills sep>ate1 ow+ to "o ( !m cutt+ obliquely across ! b$d+4 ,9 ! latt] case1 :i* is n common1 ! granophyre foll[s "o ( ! basalt-sills1 necess>ily p>t+ f ! o!r4 ,:5 "o ( ! two guid+ basalt-sills dies out1 ! granophyre may /ill cont9ue1 foll[+ ! sill :i* p]si/s4 ,if ! latt] also dies out1 :ile ! granophyre is /ill 9 "s =ce1 ! acid magma seems to h be5 reluctant to travel beyond ! limit ( ! basalt1 b has drawn t[>ds x1 & ! granophyre pres5ts a blunt laccolitic =m1 :i* contra/s ) ! acutely tap]+ edge ( a granophyre :i* dies out be=e rea*+ ! limit ( its basalt-sills4 ,if1 on ! o!r h&1 on rea*+ ! limit ( ! basalt1 ! acid magma has be5 9 su* =ce z to be driv5 fur!r1 x is usually f\nd to lose some?+ ( its regul>ity & to dep>t f ! exact horizon :i* x has hi!rto foll[$4 ,?is seems to happ51 = in/ance1 9 ! ,be9n a' ,*irn %eet1 :i*1 :5 trac$ we/w>d1 is f\nd to behave z a 'boss' & is obvi\sly transgressive1 hav+ cut across ! b$d+ ( ! /rata s z to ent] ! lime/ones1 :]e x no long] behaves 9 any degree z a sill4 ,! di/rict af=ds _m examples ( ! t5d5cy ( intrusive masses 9 g5]al to cut %>ply across ! b$s :5 !y ent] a gr\p ( lime/ones4 ,m complex examples ( acid sills are to be f\nd :]e !re h be5 ?ree or m basic %eets toge!r4 ,! great granophyre %eet already ref]r$ to at ,suisni% af=ds ! be/ illu/ration ( ?is /ructure4 ,mr4 ,h>k] has notic$ t r\nd mo/ ( its circumf]5ce !re is se5 m]ely a s+le basalt-sill pass+ "u ! granophyre4 ,probably !re has be5 ano!r simil> %eet ov] ! acid rock1 b if s1 x has be5 remov$ by erosion1 ! granophyre itself =m+ ev]y:]e ! surface ( ! plateau4 ,on ! s\!rn side1 h[ev]1 we see t ! orig9al basalt mu/ h be5 at lea/ triple1 or c\nt+ ! upp]mo/ memb]1 n[ remov$1 quadruple4 ,! granophyre has =c$ its way 9 betwe5 ! sev]al memb]s ( ! multiple basalt-sill1 ! int]m$iate ones be+ ?us completely envelop$4 ,!y are evid5tly metamorphos$ z well z ve9$ by ! granophyre1 & :5 trac$ onw>d !y give place to deta*$ portions :i*1 float+ z x 7 9 ! acid rock1 are soon lo/4 ,x is seldom easy to det]m9e :]e lay ! v5t or v5ts f :i* ! granophyre sills proce$$4 ,^? ( ! ,skye plat=m j describ$ may be *iefly conceal$ "u "s ( ! l>g] areas ( ! rock1 su* z ! %eets ( ,c>n ,de>g or ,be9n a' ,*irn4 ,b 9 sev]al places1 9 close association ) ! comp\nd sills ( granophyre & basalt1 ,mr4 ,h>k] has f\nd l>ge dyke-l bodies ( ! acid rock1 :i* may ) consid]able probability be reg>d$ z m>k+ ! position ( ! *annels by :i* ! mat]ial ( ! sills asc5d$4 ,^! bodies1 he rem>ks1 ei!r occur isolat$ by erosion1 ! sills or ! p>ts ( ! sills presum$ to h be5 9 connection ) ! dykes hav+ be5 remov$1 or are only v p>tially exhibit$ 9 direct connection ) sills /ill rema9+4 ,:]e !y c be exam9$ 9 detail !y are se5 to be dykes v>y+ up to ab\t #ajj feet 9 wid?1 b ( no great longitud9al ext5t4 ,betwe5 ,suisni% & ,cnoc ,c>na* !y be> ,e4,n4,e41 t is1 at "r angles to ! ord9>y basic dykes ( ! di/rict & p>allel to ! g5]al direction ( ! axes ( fold+1 ?\gh fur!r nor? !y *ange ?is tr5d1 b /ill rema9 p>allel to ! /rike ( ! ,lias4 ,^! dykes are compos$ ess5tially ( granophyre1 id5tical ) t ( ! sills4 ,9 "s cases1 !y are flank$ ) basalt-dykes on "o or bo? sides1 or ! =m] exi/5ce ( su* lat]al dykes is indicat$ by p>tly-de/roy$ inclusions ( ! basic rock 9 ! granophyre4 ,! basalt f\nd 9 ^! cases is id5tical ) t ( ! basic sills1 & %[s ! same relation to ! granophyre4 ,discont9uity & failure ( ! basalt are common]1 h[ev]1 9 ! dykes ?an 9 ! sills--a diff]5ce presumably attributable to m en]getic de/ructive action ( ! acid magma :5 x 0 hott] & fre%]4 ,^! suppos$ fe$]s ( ! granophyre sills are c]ta9ly 9 "s cases1 & h possibly be5 9 all1 d\ble or triple dykes4 ,! acid magma ?us appe>s n only to h spread lat]ally along ! same plat=ms z ! e>li] basalts1 b to h rea*$ ^! levels by ris+ ?r\gh ! same fissures :i* _h already giv5 passage to ! basic magma4#dca ,footnote #dca3 ,,ms4 notes suppli$ by ,mr4 ,h>k]4 ,! granophyre sills :i*1 z already /at$1 c be foll[$ z an int]rupt$ b& f ,suisni% ,po9t to ! ,s\nd ( ,scalpa1 em]ge aga9 beyond ,lo* ,sliga*an & also 9 ! isl& ( ,raasay1 :]e a great %eet ( ! acid rock cov]s an area ( ab\t five squ>e miles4 ,?is tract has rec5tly be5 mapp$ = ! ,geological ,survey by ,mr4 ,h4 ,b4 ,woodw>d1 :o has f\nd x to h be5 intrud$ across ! ,jurassic s]ies1 a l>ge "p ( its mass com+ 9 irregul>ly ab\t ! top ( ! ?ick :ite s&/ones ( ! ,inf]ior ,oolite4 ,b x desc5ds b5ea? ! ,second>y rocks altoge!r1 & 9 "s places int]v5es betwe5 ! base ( ! ,infra-liassic conglom]ates & ! ,torridon s&/one4 ,its irregul> c\rse transgressively across ! ,mesozoic =mations is probably to be reg>d$ z ano!r example ( ! intrusion ( ! acid mat]ial pref]5tially along ! l9e ( uncon=mability betwe5 ! old] rocks & ! ,t]ti>y basalts1 n[ ne>ly all remov$ f ,raasay by d5udation1 ?\gh ! intrusion does n rigidly foll[ t l9e ( division1 b sometimes desc5ds bel[ x4 ,! c5tral portions ( ?is ,raasay granophyre possess ! ord9>y /ructures ( ! correspond+ rocks 9 ,skye4 ,!y %[ a f9ely cry/all9e-granul>1 micropegmatitic base1 ?r\gh :i* l>ge felsp>s & qu>tzes are disp]s$4 ,b at ! upp] & "u junction ) ! s$im5t>y rocks1 beautiful sph]ulitic /ructures are develop$4 ,?is is well se5 on ! %ore ne> ! ,po9t ( ,suisni% 7,raasay71 :]e1 bel[ ! ,lias ,lime/ones1 ! top ( ! granophyre appe>s1 & :]e its bottom is se5 to lie on ! ,torridon s&/one4 ,?is granophyre %eet pres5ts a fur!r po9t ( int]e/ inasmu* z x appe>s to h pres]v$ "o ( ! dyke-l masses :i* may m>k *annels ( escape f ! g5]al body ( ! acid magma bel[4 ,ne> ! ,manse ! section repres5t$ 9 ,fig4 #cgc may be obs]v$4 ,ow+ to great d5udation1 ! massive %eet ( granophyre has be5 cut into isolat$ outli]s :i* cap ! l[ hills1 & ! rock may be se5 desc5d+ ?r\gh ! ,jurassic s&/ones1 :i* 9 places are mu* indurat$4 ,x is obs]vable t ! am\nt ( contact-metamorphism induc$ by ! granophyre sills ^u ! rocks betwe5 :i* !y h be5 inject$ is1 9 g5]al1 comp>atively trifl+4 ,x is = ! mo/ "p a m]e induration1 sometimes accompani$ ) di/ortion & fracture4 ,illu/ration3 ,fig4 #cgc4--,section to %[ ! connection ( a sill ( ,granophyre ) its probable funnel ( supply1 ,raasay4 a a1 ,jurassic s&/ones2 b1 granophyre4 ,illu/ration3 ,fig4 #cgd4--;,granophyre sill re/+ on ,l[] ,lias %ales ) a dyke ( basalt pass+ lat]ally into a sill1 ,suisni% ,po9t1 ,isle ( ,raasay4 ,al?\gh ! intrusion ( ! granophyre sills has be5 subsequ5t to t ( ! basalt-%eets ) :i* !y are s g5]ally associat$1 we may expect t z !re is a s]ies ( po/-granophyre basic dykes1 s !re may be "s basic sills lat] ?an ! injections ( ! acid %eets4 ,! ,raasay granophyre appe>s to furni% an example ( su* a lat] basic intrusion4 ,at ! ,po9t ( ,suisni% on t isl& ,i h obs]v$ ! relations %[n 9 ,fig4 #cgd4 ,!re ! d>k %ales ( ! ,l[] ,lias 7a a7 are imm$iately ov]la9 by ! granophyre sill 7b71 & are cut by a basalt-dyke :i*1 :5 x rises to ! base ( ! granophyre1 turns abruptly to "o side1 & !n pursues its c\rse z a sill 7c7 betwe5 ! granophyre & ! %ales4 ,!re c be little d\bt t ?is intrusion is lat] ?an ! granophyre4 ,"h a basic sill is int]pos$ at ! bottom ( ! acid %eet2 & is visibly connect$ ) ! actual fissure up :i* its molt5 mat]ial 0 impell$4 ii4 ,,! ,,acid ,,dykes ,,& ,,ve9s ,besides bosses & sills1 ! acid rocks ( ! ,inn] ,hebrides take ! =m ( ,dykes & ,ve9s :i* h invad$ ! o!r memb]s ( ! volcanic s]ies4 ,"s ( ^! h already be5 ref]r$ to2 b a m p>ticul> description ( ! v5\s developm5t ( ! acid rocks z a :ole is n[ requir$4 ,z reg>ds _! occurr5ce & di/ribution1 !y pres5t two phases1 :i*1 h[ev]1 _c always be di/+ui%$ f ea* o!r4 ,on ! "o h&1 !y are f\nd abundantly ei!r directly proce$+ f ! bosses 7m r>ely f ! sills71 or 9 su* imm$iate proximity & close relation%ip to ^! z to indicate t !y mu/ be reg>d$ z apophyses f ! l>g] bodies ( eruptive mat]ial4 ,on ! o!r h&1 !y pres5t !mselves z solit>y individuals1 or 9 gr\ps at a di/ance ( sometimes sev]al miles f any visible boss ( granophyre4 ,9 su* cases1 x is ( c\rse obvi\s t ?\gh n expos$ at ! surface1 !re may be a l>ge mass ( ! acid magma at no great di/ance b5ea?1 & t ^! isolat$ dykes & ve9s d n ess5tially diff] 9 orig9 f ^? ( :i* ! relations to eruptive bosses c be satisfactorily obs]v$ or inf]r$4 ,consid]$ z a petrographical gr\p1 ^! ,dykes & ,ve9s are m>k$ by ! foll[+ *>act]s4 ,at ! "o extreme1 we h ?or\ghly vitre\s rocks 9 ! pit*/ones4 ,f ^!1 ?r\gh v>i\s degrees ( devitrification1 we are l$ to completely li?oid felsites1 qu>tz-porphyries or rhyolites4 ,micropegmatitic /ructure is commonly pres5t1 & z x increases 9 developm5t1 ! rocks assume ! ord9>y *>act]s ( granophyre4 ,occasionally ! /ructure becomes microgranitic 9 ! imm$iate p]iph]y ( a boss :]e9 a granitic "* has be5 assum$4 ,view$ z a :ole1 h[ev]1 x may be said t ! dull li?oid rocks ( ! dykes & ve9s c g5]ally be resolv$ "u ! microscope into "s v>iety ( granophyric porphyry or granophyre4 ,a *>act]i/ic feature 9 ! granophyric1 felsitic or rhyolitic dykes & ve9s is ! pres5ce ( sph]ulitic /ructure 7,figs4 #cge1 #cgg74 ,9 "s cases ?is /ructure is h>dly traceable save ) ! aid ( ! microscope1 b f ^! m9ute proportions x may be foll[$ up to su* a /rong developm5t t ! individual sph]ulites may be an in* or two 9 diamet]1 & lie cr[d$ toge!r1 l ! r\nd pebbles ( a conglom]ate4 ,! /ructure is a contact ph5om5on1 be+ specially m>k$ along ! m>g9 ( ! dykes1 z x is on ! edge ( sills & bosses4 ,9 ! ,/ra? di/rict ( ,skye1 ,mr4 ,cl\gh & ,mr4 ,h>k] h obs]v$ t ! sph]ulites are apt to be gr\p$ 9 p>allel l9es s z to =m rod-l aggregates along ! walls1 & t :]e ! rock is fairly fre% ! c5tre ( ! dyke sometimes consi/s ( glassy pit*/one1 s t ! sph]ulitic felsite or granophyre is probably devitrifi$ pit*/one4 ,frequ5tly fl[-/ructure is admirably develop$ 9 ^! dykes1 ! /reaky lay]s ( devitrification fl[+ r\nd ! sph]ulites & any enclos$ fragm5ts z p]fectly z 9 any rhyolitic lava 7,fig4 #cgh74 ,illu/ration3 ,fig4 #cge4--,wea!r$ surface ( sph]ulitic granophyre f dyke 9 b&$ gabbros1 ,druim an ,eidhne1 ,meall ,de>g1 ,gl5 ,sliga*an1 ,skye4 ,natural size4 ,9 reg>d to _! modes ( occurr5ce1 ! dykes ( acid mat]ial diff] 9 "s important respects f ^? ( basic composition4 ,m especially !y are apt to assume ! irregul> v5\s =m1 r ?an ! v]tical wall-l "* ( ord9>y dykes4 ,!y take ! =m ( dykes1 p>ticul>ly :]e _! mat]ial has be5 guid$ 9 its uprise by "o or m already exi/5t basic or int]m$iate dykes1 z 9 ! comp\nd dykes1 already describ$4 ,! conditions = _! production mu/ ?us h be5 ess5tially diff]5t f ^? ( ! great body ( ! basic dykes4 ,_! intrusion 0 n m>k$ by any g5]al & widespread fissur+ ( ! e>?'s cru/1 su* z prep>$ r5ts = ! reception ( ! basalt & &esite dykes4 ,!y 7 r accompanim5ts ( ! protrusion ( l>ge masses ( acid magma into ! t]re/rial cru/4 ,?is magma1 z we h se51 0 (t5 m>k$ly liquid1 & 0 impell$1 sometimes ) :at might be call$ explosive viol5ce1 into ! irregul> cracks ( ! %att]$ surr\nd+ rocks or into pre-exi/+ dyke-fissures4 ,h5ce long /raight dykes ( ! acid rocks are mu* less common ?an %ort irregul> tortu\s ve9s & /r+s4 ,illu/ration3 ,fig4 #cgf4--,plan ( portion ( ! ridge nor? ( ,druim an ,eidhne1 ,gl5 ,sliga*an1 ,skye1 %[+ ?ree dykes issu+ f a mass ( granophyre4 a1 gabbros2 b1 granophyre2 ,i4 ,,ii4 ,,iii41 ?ree dykes proce$+ f ! granophyre4 ,! arr[s %[ ! direction ( dip ( ! b&s ( gabbro4 ,mu* diff]5ce may be notic$ among ! granophyre bosses 9 reg>d to _! giv+ (f a fr+e ( apophyses4 ,?us1 along ! well-expos$ b\nd>y ( ,be9n-an-,dubhai* 9 ,skye1 ?\gh ! edge ( ! boss is rem>kably not*$1 h>dly any ve9s des]v+ ! "n div]ge f x4 ,on ! o!r h&1 ! ridge ( ,meall ,de>g at ! head ( ,gl5 ,sliga*an1 already ref]r$ to1 is di/+ui%$ by ! numb] & v>iety ( ! dykes & ve9s :i* proce$ f ! granophyre & trav]se ! b&$ gabbros4 ,z ?is locality has be5 else:]e fully describ$1 ,i w give "h only ! lead+ /ructural features :i* x pres5ts4#dcb ,footnote #dcb3 ,pr(essor ,judd 7,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 xlix4 7#ahic71 p4 #age7 describ$ ! granophyre dykes ( ?is locality z inclusions ( ,t]ti>y granite 9 ! gabbro1 & cit$ !m 9 pro( ( 8 cont5tion t ! acid eruptions ( ! ,we/]n ,isles are old] ?an ! basic4 ,_! true "* 0 %[n by me 9 a pap] publi%$ 9 ! ,qu>t4 ,j\rn4 ,geol4 ,soc4 vol4 #a4 7#ahid71 p4 #bab4 ,illu/ration3 ,fig4 #cgg4--,wea!r$ surface ( sph]ulitic granophyre f dyke 9 b&$ gabbros1 ,druim an ,eidhne1 ,meall ,de>g1 ,gl5 ,sliga*an1 ,skye4 ,natural size4 ,)9 a horizontal di/ance ( less ?an #ajj y>ds ?ree well-m>k$ dykes issue f ! sph]ulitic edge ( ! ,meall ,de>g granophyre1 & run 9 a s\?-ea/]ly direction 9 ! h&$ gabbros 7,fig4 #cgf74 ,! mo/ nor!rly ( ^! is traceable 9 a ne>ly /raight l9e = #hjj feet4 ,! c5tral dyke1 :i* c be foll[$ = #bjj feet or m1 rises z a b& six to t5 feet broad betwe5 ! d>k walls ( gabbro z repres5t$ 9 ,fig4 #cgi4 ,^! dykes are m>k$ by ! mo/ p]fectly develop$ sph]ulitic & fl[-/ructures 7,figs4 #cge1 #cgg74 ,num]\s deta*$ portions ( o!r dykes & also irregul> ve9s are to be obs]v$ cutt+ ! b&$ gabbros all ov] ! ridge ( ,druim an ,eidhne = a di/ance ( a mile or m4 ,_m ( ^! exhibit ! same exquisitely beautiful sph]ulitic & fl[-/ructure display$ by ! dykes :i* c actually be trac$ into ! ma9 body ( granophyre4 ,! l9es ( fl[ con=m to e s9uosity 9 ! b\nd>y-walls ( gabbro1 & sometimes sweep r\nd & enclose blocks ( t rock4 ,! example ( ?is /ructure1 giv5 9 ,fig4 #cgh1 %[s h[ ^! l9es1 curv+ r\nd projections & b5d+ into eddy-l swirls1 exhibit ! motion ( a visc\s lava fl[+ 9 a cleft betwe5 two walls ( solid rock4 ,sometimes ! lam9 ( fl[ h be5 disrupt$1 & brok5 portions ( !m h be5 c>ri$ onw>d & envelop$ 9 ! yet unconsolidat$ mat]ial4 ,c]ta9 portions ( ?is dyke are ri*ly sph]ulitic1 ! sph]ulites v>y+ f ! size ( small peas up to t ( t5nis-balls4 ,occasionally two l>ge sph]ulites h coalesc$ into an #h-%ap$ concretion1 & x may be obs]v$ 9 "s cases t ! sph]ulites are holl[ %ells4 ,illu/ration3 ,fig4 #cgh4--,plan ( pale granophyric dyke1 ) sph]ulitic & fl[-/ructure1 cutt+ & enclos+ d>k gabbro1 ,druim an ,eidhne4 ,illu/ration3 ,fig4 #cgi4--;,dyke 7six to t5 feet broad7 proce$+ f a l>ge body ( granophyre & trav]s+ gabbro1 f ! same locality z ,figs4 #cge & #cgg4 ,a rem>kable feature has be5 rec5tly obs]v$ by ,mr4 ,h>k] among ! abundant granophyre dykes & ve9s :i* int]sect ! gabbros & old] rocks1 along ! ea/]n flanks ( ! ,r$ ,hills ( ,skye betwe5 ,broad=d & ! ,s\nd ( ,scalpa4 ,broad dykes ( granophyre :i* trav]se ! ,cambrian lime/one ( t di/rict might be suppos$ at fir/ sight to be cut (f by ! intrusions ( gabbro4 ,b clos] exam9ation proves t _! app>5t truncation arises f _! sudd5ly break+ up into a network ( small ve9s :]e !y abut aga9/ ! basic rock4 ,?is /ructure evid5tly belongs to ! same type z t ( ! ,/4 ,kilda granophyre4 ,illu/ration3 ,fig4 #chj4--,section ( intrud$ ve9s ( v>i\s acid rocks above ,riv] ,cla*aig1 ,mull4 a a1 basalt1 dol]ite1 etc42 b b1 granophyre4 ,comp\nd dykes & sills1 :]e "o or m ( ! injections has consi/$ ( acid mat]ial1 h be5 already notic$ z intimately associat$ toge!r 9 ,skye 7p4 #afb74 ,dykes ( ?is nature are m p>ticul>ly abundant 9 ,/ra?1 especially along its ea/]n side4 ,9 addition to ! examples cit$ already f t di/rict1 ,i may ref] to o!r two :i* int]sect ! ,middle ,lias %ales & lime/ones 9 ! isl& ( ,scalpa4 ,!y are bo? comp\nd dykes1 b ! m basic m>g9al b&s are n always cont9u\s1 hav+ possibly be5 "h & !re dissolv$ by ! acid invasion4 ,?\gh !y d n %[ any di/9ct sph]ulitic =ms1 ! pres5ce ( fl[-/ructure is indicat$ by ! ?9 slabs into :i* ! rocks wea!r p>allel to ! dyke-walls4 ,! rock 9 ea* case is a f9e-gra9$ felsitic mass1 ) bi-pyramidal cry/als ( qu>tz4 ,x is obs]vable t :]e ^! dykes come directly aga9/ ! ,liassic /rata1 ! latt] are m s]i\sly indurat$ ?an :]e !y are trav]s$ by ! ord9>y basic dykes4 ,9 ! c5tral m\nta9\s tract ( ! isl& ( ,mull ve9s ( acid mat]ial are extraord9>ily abundant4 ,!y probably proce$ f a mu* l>g] subt]ranean body ( granophyre ?an any ( ! comp>atively small bosses ( ?is rock :i* appe> at ! pres5t surface ( ! gr\nd4 ,!y %[ !mselves p>tly at ! m>g9s ( ! visible bosses1 b mu* m pr(usely 9 t tract ( alt]$ basalt1 ) intrusive %eets & dykes ( basalt1 dol]ite & gabbro1 :i* lies )9 ! great r+ ( heights betwe5 ,lo* na ,keal & ,lo* ,spelve4 ,9 "s areas1 ! am\nt ( inject$ mat]ial appe>s to equal ! mass ( m basic rock into :i* x has be5 ?ru/4 ,pale grey & yell[i% porphyries & granophyres1 v>y+ f ?ick dykes d[n to ! m]e/ ?reads1 ramify 9 an intricate network ?r\gh ! d>k rocks ( ! hills1 z %[n 9 ! accompany+ illu/ration 7,fig4 #chj71 :i* repres5ts a portion ( ! hillside betwe5 ,be9n ,fhada & ! ,cla*aig ,riv]4 ,su* a pr(usion ( ve9s probably indicates ! exi/5ce "h ( "s l>ge mass ( granophyre or granite1 at no great dep? b5ea? ! surface4 ,9 ,mull1 z 9 ! o!r isl&s ( ! ,inn] ,hebrides1 two horizons on :i* protrusions ( acid mat]ials h be5 specially abundant1 are ! base ( ! b$d$ basalts ( ! plateau & ! bottom ( ! ?ick %eets ( gabbro4 ,dykes & ve9s ( granophyre1 qu>tz-porphyry1 felsite & o!r alli$ rocks are sometimes cr[d$ toge!r along ^! two horizons1 ?\gh !y may be infrequ5t above or bel[ !m4 ,illu/rations ( solit>y ve9s 9 ! mid/ ( unalt]$ plateau-basalts or 9 old] rocks may be ga!r$ f _m p>ts ( ! ,we/]n ,isles4 ,"s rem>kable in/ances are to be se5 among ! basalts t =m ! t]rac$ slopes on ! nor? side ( ,lo* ,sliga*an4 ,sev]al ?ick dykes ( granophyre run up ! declivity1 cutt+ across hundr$s ( feet ( ! ne>ly level basalt-b$s4 ,"s ( !m c be se5 on ! %ore pass+ "u ! sea4 ,!y tr5d 9 a ,s4,s4,e4 direction t[>ds ,glamaig1 & !y are n improbably apophyses f t huge boss1 ! ne>e/ edge ( :i* is ?ree-qu>t]s ( a mile di/ant4 ,ano!r example may be cit$ f ! basalt-outli] ( ,/ra?aird1 :]e two ve9s ( felsite1 "o ( !m a pale fl9ty rock %[+ fl[-/ructure p>allel to ! walls1 may be se5 on ! we/ front ( ,b5 ,meabo/4 ,9 ?is case1 ! ve9s are ?ree miles & a half f ! granophyre mass ( ,/ra? na ,crei!a* to ! nor?1 f\r miles f t ( ,be9n an ,dubhai* to ! nor?-ea/1 & ne>ly ?ree miles f t ( ,coire ,uaignei* at ! foot ( ,bla? ,bhe9n4 ,a special place mu/ be res]v$ = ! pit*/one-ve9s4 ,ev] s9ce ! e>ly explorations ( ,jameson & ,maccullo*1 ! ,we/ ( ,scotl& has be5 not$ z "o ( ! *ief ,european di/ricts = ^! vitre\s rocks4 ,f ,skye to ,arran1 & !nce to ,antrim1 _m localities h furni%$ examples ( !m1 b always )9 ! limits ( ! ,t]ti>y volcanic region4 ,t all ( ! pit*/ones are ( ,t]ti>y age _c1 ( c\rse1 be prov$1 = "s ( !m are f\nd trav]s+ only ,palozoic rocks1 & ( ^! all t c be absolutely affirm$ is t !y mu/ be y\ng] ?an ! ,c>bonif]\s or ev5 ! ,p]mian sy/em4 ,b1 z mo/ ( !m are unque/ionably p>ts ( ! ,t]ti>y volcanic s]ies1 !y are probably all ref]able to t s]ies4 ,n only s1 b !re is1 ,i ?9k1 good reason to place !m among its v y\nge/ memb]s4 ,x is a significant fact t !y almo/ always occur ei!r 9 or close to granophyre or granite bosses1 ! comp>atively late orig9 ( :i* has n[ be5 prov$4 ,illu/ration3 ,fig4 #cha4--,pit*/one ve9 trav]s+ ! b$d$ basalts1 ,rudh an ,tangairt1 ,eigg4 ,! fir/ pit*/one obs]v$ 9 ,skye 0 f\nd by ,jameson on ! flanks ( ! great granophyre cone ( ,glamaig4 ,ano!r rises on ! side ( ! porphyry mass ( ,glas ,bhe9n ,bheag1 9 ,/ra? ,beg4 ,sev]al occur at ! foot ( ,be9n na ,calli*4 ,9 ,rum1 ,i f\nd a pit*/one ve9 trav]s+ ! we/]n slopes ( ! wide granophyre boss ( ,orval4 ,9 ,eigg1 ! well-kn[n ve9s ( ?is rock int]sect ! plateau-basalts 7,fig4 #cha71 b !y are accompani$1 ev5 )9 ! same fissure1 ) granophyre1 & 9 _! ne> neighb\rhood lie ! masses ( ?is rock already allud$ to4#dcc ,9 ,antrim1 pit*/one & obsidian occur 9 ! mid/ ( ! rhyolite4 ,! only m>k$ exceptions to ! g5]al rule1 ) :i* ,i am acqua9t$1 are ^? ( ! isl& ( ,arran4 ,mo/ ( ! pit*/one-ve9s 9 t di/rict trav]se ! r$ s&/ones :i* may be ,p]mian4 ,b none ( !m are f> remov$ f ! great granite boss ( ! nor!rn half ( ! isl&1 :ile l>ge masses ( qu>tz-porphyry1 :i* /rik+ly resemble "s ( ^? ( ,skye & ,mull1 lie /ill ne>] to !m4 ,x is also wor?y ( notice t pit*/one-ve9s rise ?r\gh ! ,arran granite boss itself1 ! probably ,t]ti>y date ( :i* has be5 already discuss$4 ,footnote #dcc3 ,= an acc\nt ( ! pit*/one ve9s ( ,eigg1 see ,qu>t4 ,j\rn4 ,geol4 ,soc4 xxvii4 p4 #bii4 ,?is common association ( pit*/one-ve9s ) ! ,t]ti>y eruptive bosses ( acid rocks c h>dly be a m]e accid5tal co9cid5ce4 ,x seems to prove a r5ew$ extravasation ( acid mat]ial1 n[ 9 vitre\s =m1 f ! same v5ts t _h suppli$ ! granitoid1 granophyric1 porphyritic & felsitic v>ieties ( e>li] protrusions4 ,we mu/ rememb] t ! pit*/one-ve9s are n m]e local glassy p>ts ( ! l>g] bodies ( granophyre or granite 9 :i* !y lie4 ,_! m>g9s are %>ply def9$2 !y are inde$ 9 all respects z manife/ly intrud$1 & !re=e lat] masses1 z are ! basalt-dykes4 ,_! occurr5ce1 !re=e1 )9 ! acid bosses proves !m to be y\ng] ?an ^! memb]s ( ! ,t]ti>y volcanic s]ies4 ,:e!r !y are also lat] ?an ! late/ basalt-dykes _c yet be decid$1 = ,i h nev] succe$$ 9 f9d+ an example ( ! int]section ( ^! two gr\ps ( ve9s & dykes4 ,b1 ) ?is possible exception1 ! pit*/ones are ! mo/ rec5t ( all ! eruptive rocks ( ,brita94 ,z a rule1 ! intrusive pit*/ones occur z ve9s :i* _c be trac$ f>1 & :i* v>y f a few y>ds to less ?an an in* 9 wid?4 ,!y g5]ally %[ consid]able irregul>ity 9 bread? & direction1 sometimes s5d+ out /r+s into ! surr\nd+ rock 7,fig4 #cha74 ,! out] portions are n infrequ5tly m glassy & obsidian-l ?an ! int]ior4 ,occasionally ! vitre\s "* disappe>s by devitrification1 & ! rock assumes ! texture ( a compact felsite or ( a sph]ulitic rock4 ,among ! lat] movem5ts ( ! acid magma acc\nt mu/ be tak5 "h ( ! pale f9e-gra9$ ve9s :i* h already be5 ref]r$ to z trav]s+ ! granophyre bosses4 ,^! intrusions1 s well se5 9 ! bosses ( ,skye & ,/4 ,kilda1 are (t5 s close 9 texture t !y may be call$ qu>tz-felsites4 ,_! %>ply-def9$ edges & felsitic "* suffice to sep>ate !m f :at are t]m$ ve9s ( segregation4 ,9 at lea/ "o in/ance1 t ( ,meall ,de>g1 already cit$1 a mass ( typical granophyre :i* has develop$ sph]ulitic & fl[-/ructures along its m>g91 & :i* s5ds out dykes hav+ ! v same /ructures = a di/ance ( sev]al hundr$ feet across ! b&$ gabbros1 is itself trav]s$ by a dyke ( precisely simil> "*4 ,"h we see t aft] ! intrusion ( its apophyses1 & aft] its own consolidation 9 ! upp] p>ts1 ! granophyric magma t rose into r5ts 9 ! solidifi$ portion reta9$ ! same t5d5cy to produce l>ge sph]ulites z x _h %[n at fir/4 ,! f9e felsitic ve9s t trav]se ! granophyre ( ! ,r$ ,hills are n[ be+ mapp$ by ,mr4 ,h>k] dur+ ! progress ( ! ,geological ,survey4 ,he has n yet obta9$ evid5ce ( ! age ( ^! ve9s 9 relation to ! late/ basic dykes4 ,he has obs]v$ t !y appe> to be on ! :ole r less acid ?an ! mat]ial ( ! surr\nd+ bosses1 ?\gh !y 7 probably all connect$ ) ! same und]ly+ acid magma f :i* ! bosses 7 protrud$4 ,a some:at simil> relation has be5 notic$ betwe5 old] granites & _! surr\nd+ dykes1 z 9 ,cornwall & ,gall[ay4 ,illu/ration3 ,,to ,,accompany ,,sir ,,ar*ibald ,,geikie',s ,,anci5t ,,volcanoes ,,( ,,brita9 ,map ,,vii ,,map ,,( ,,! ,,t]ti>y ,,volcanic ,,di/rict ,,( ,,nor? ,,ea/ ,,irel& ,! ,ed9burgh ,geographical ,in/itute ,copyright ,j4 ,g4 ,b>?olomew ,,*apt] ,,xlix ,,! ,,subsid5ces ,,& ,,dislocations ,,( ,,! ,,plateaux ,!re c be no d\bt t consid]able alt]ations ( level h tak5 place ov] ! volcanic areas ( ,nor?-,we/]n ,europe s9ce ! eruptions t produc$ ! basalt-plateaux1 ,^! alt]ations embrace g5]al & local subsid5ces1 & also dislocations by :i* consid]able displacem5ts ( ! cru/ ei!r 9 a d[nw>d or upw>d direction h be5 effect$4 i4 ,,subsid5ces ,! m]e fact t 9 _m places ! l[] memb]s ( ! s]ies ( t]re/rial lavas h be5 subm]g$ "u ! sea may be tak5 to prove a subsid5ce s9ce old] ,t]ti>y "t4 ,along ! we/ coa/ ( ,skye ?is depression is well %[n by ! almo/ entire concealm5t ( ! bottom ( ! plateau "u ! ,atlantic4 ,9 ! ,f>oe ,isles ! subsid5ce has advanc$ /ill fur!r1 = n a trace ( ! und]ly+ plat=m on :i* ! basalts re/ rema9s above wat]4 ,9 ,icel&1 too1 ! complete subm]g5ce ( ! base ( ! ,t]ti>y volcanic %eets po9ts to a widespread subsid5ce ( t region4 ,ano!r /rong argum5t 9 fav\r ( consid]able depression may be d]iv$ f a comp>ison ( ! subm>9e topography ) t ( ! tracts above sea-level4 ,x is obvi\s t ! same =ms ( cont\r :i* are conspicu\s on ! l& are prolong$ "u ! ,atlantic4 ,if we are correct 9 reg>d+ ! valleys z great l9es ( subrial erosion1 _! prolongations z fjords & subm>9e tr\ghs mu/ be consid]$ z hav+ _h a simil> orig94 ,we c ?us c>ry d[n ! surface ( erosion sev]al hundr$ feet l[] ?an ! l9e along :i* x disappe>s "u ! waves4 ,i "k no locality :]e ?is k9d ( reason+ is s impressively en=c$ ^u ! m9d z ! we/ end ( ! ,scuir ( ,eigg4 ,! old riv]-b$ & its pit*/one t]m9ate abruptly at ! top ( a great precipice4 ,assur$ly !y mu/ once h cont9u$ mu* fur!r we/w>d1 z well z ! %eets ( basalt t =m ! ma9 "p ( ! cliff4 ,yet ! sea 9 front ( ?is truncat$ face ( rock rapidly deep5s to fully #ejj feet 9 "s places4 ,_h any su* holl[ exi/$ 9 ! volcanic p]iod x w\ld h be5 fill$ up by ! long-cont9u$ outfl[+s ( basalt4 ,mak+ e all[ance = conceal$ faults & local subsid5ces1 we c only acc\nt = ?is subm>9e topography by reg>d+ x z hav+ be5 c>v$ out1 toge!r ) ! topography ( ! l&1 at a "t :5 ! level ( ! latt] 0 at lea/ #ejj feet high] ?an x is n[4 ,! subsid5ce :i* is ?us indicat$ along ! :ole ( ! ,nor?-,we/ ( ,europe probably v>i$ 9 am\nt f "o region to ano!r4 ,we seem to h traces ( su* inequalities 9 ! v>y+ incl9ations ( diff]5t segm5ts ( ! basalt-plateaux4 ,! angles ( incl9ation are almo/ always g5tle1 b !y diff] s mu* 9 direction f isl& to isl&1 & ev5 among ! sev]al di/ricts ( ! same isl&1 z to indicate t c]ta9 portions ( ! volcanic pla9 h sunk r m ?an o!r portions4 ,?us 9 ! ,f>oe ,isl&s1 :]e ! b>e cliffs all[ ! v>y+ angles ( incl9ation to be easily det]m9$1 a g5]al g5tle dip ( ! basalts 9 a s\?-ea/]ly direction has be5 not$ among ! c5tral & nor!rn isl&s by previ\s obs]v]s4 ,?is incl9ation1 h[ev]1 is replac$ among ! s\!rn isl&s by an equally g5tle dip t[>ds ! nor?-ea/4 ,! c5tre ( depression w\ld ?us seem to lie some:]e ab\t ,s& & ,sku4 ,! highe/ angle ( incl9ation :i* ,i notic$ any:]e 0 at ,mygg5aes1 :]e ! basalts dip ,e4,s4,e4 at ab\t #ae4 ,among ! ,we/]n ,isles1 also1 :]e simil> v>iations 9 ! incl9ation ( ! basalt-%eets are obs]vable1 x might be possible by c>eful survey to asc]ta9 ! probable position ( ! areas ( maximum depression1 & to %[ to :at ext5t diff]5tial movem5ts h affect$ ! orig9ally ne>ly level volcanic floor4 ,x w\ld d\btless be f\nd t ev]y:]e ! dom9ant movem5t has be5 "o ( subsid5ce4 ,! va/ outp\r+s ( lava w\ld t5d to leave ! ov]ly+ cru/ unsupport$1 & to cause x to s9k into ! cavities ?us produc$4 ,p]haps ! mo/ ext5sive subsid5ce ( ?is k9d1 at lea/ t :i* admits ( mo/ satisfactory inve/igation1 because x /ill rema9s above sea-level1 is display$ by ! va/ holl[ 9 ! ,antrim plateau1 :i* embraces ! bas9 ( ,l\gh ,neagh & ! valley ( ! ,l[] ,bann4 ,?is depression measures ab\t #fj miles 9 l5g? by ab\t #bj 9 bread?4 ,its axis foll[s ! ,n4,n4,w4 tr5d s *>act]i/ic ( ! volcanic features ( ,t]ti>y "t4 ,! depression may be said to involve ! entire basaltic plateau ( ,antrim1 = ) ! exception ( a few insignificant areas along ! bord]s1 especially on ! ea/ side betwe5 ,l>ne & ,cu%5dall1 ! :ole region slopes inw>d f its m>g9al l9e ( esc>pm5ts1 :i* rea* heights ( #ahjj feet & upw>ds1 t[>ds ! great holl[ 9 its c5tre 7see ,map ,,vii474 ,l\gh ,neagh1 :i* occupies ! deepe/ "p ( ?is holl[1 & cov]s ab\t "o-eigh? ( ! :ole area ( subsid5ce1 is ! l>ge/ %eet ( fre% wat] 9 ! ,briti% ,isles1 = x exce$s #aej squ>e miles 9 ext5t ( surface4 ,yet1 = its size1 x is "o ( ! %all[e/ ( our lakes1 its av]age dep? be+ less ?an #dj feet4 ,its %all[ness1 comp>$ ) its wide area1 m>ks x out 9 /rong contra/ to mo/ ( ! l>g] ,briti% lakes4 ,its surface is only #dh feet above ! level ( ! sea4 ,! orig9 ( ,l\gh ,neagh1 ! !me ( v>i\s leg5ds1 has be5 s]i\sly discuss$ by diff]5t writ]s1 b mo/ exhau/ively by ! late ,e4 ,t4 ,h>dman ( ! ,geological ,survey4#dcd ,?is au?or connect$ ! =mation ( ! lake-bas9 ) a s]ies ( l>ge faults :i* are f\nd int]sect+ ! rocks ar\nd ! bas91 & pass+ "u ! wat] 9 a g5]al nor?-ea/]ly direction4 ,he %[$ t ^! faults h produc$ s]i\s displacem5ts ( ! /rata1 am\nt+ sometimes to z mu* z #bjjj feet1 & he believ$ t x 0 by ! concurr5t effect ( su* dislocations t ! depression ( ,l\gh ,neagh _h be5 caus$4 ,footnote #dcd3 ,on ! ,age & ,=mation ( ,l\gh ,neagh1 ,j\rn4 ,roy4 ,geol4 ,soc4 ,irel&1 vol4 iv4 7#ahge-gf71 p4 #agj2 also ,explanation ( ,%eet #ce ( ! ,geol4 ,surv4 ,irel& 7#ahgg71 p4 #gb4 ,x is possible t ^! displacem5ts may h contribut$ to at lea/ ! e>li] /ages 9 ! hi/ory ( ! ,antrim subsid5ce4 ,!y h und\bt$ly tak5 place aft] ! outp\r+ ( ! basalts1 = ^! rocks are involv$ 9 _! effects4 ,b 9 ! holl[ ( ! ,bann valley nor? ( ,l\gh ,neagh ! faults :i* h be5 detect$ 9 ! basaltic plateau are few & trifl+4 ,! bold & b>e esc>pm5ts1 t s cle>ly display ! relations ( ! rocks1 reveal few traces ( any important transv]se dislocations4 ,nor has any pro( ( l>ge longitud9al faults p>allel ) ! axis ( depression be5 obta9$ )9 ! area ( ! ,bann valley4 ,! e>lie/ evid5ce = ! exi/5ce ( a lake on ! site ( ! pres5t ,l\gh ,neagh has be5 suppos$ to be furni%$ by c]ta9 f9e clays1 s&s1 seams ( lignite & clay-iron/one1 :i* h be5 ref]r$ to ! ,plioc5e p]iod4 ,^! deposits h be5 reg>d$ z indicat+ ! accumulation ( f9e s$im5t ) drift vegetation br\ght d[n into a quiet lake by /reams ent]+ f ! s\?4 ,_! fre%-wat] orig9 0 believ$ to be fur!r corroborat$ by ! occurr5ce ( %ells belong+ to ! lacu/r9e or fluviatile g5us1 ,unio4#dce ,footnote #dce3 ,^! %ells 7 reg>d$ z =ms ( ,unio by ! late ,w4 ,h4 ,baily2 b ,dr4 ,h5ry ,woodw>d assign$ !m to ,mytilus4 ,see ,pr(4 ,hull's ,physical ,geology & ,geography ( ,irel&1 #bnd edit4 p4 #aja4 ,! %ells h be5 m rec5tly dug out by ,mr4 ,clem5t ,reid1 :o has f\nd !m to be ! common ,mytilus edulis4 ,! ?ickness ( ?is s]ies ( /rata1 _! position above sea-level1 & _! di/ribution are important p>ts ( ! evid5ce = ! geological hi/ory ( ! locality4 ,at "o place ! deposits are said to h be5 bor$ ?r\gh to a dep? ( #bid feet1 & ,mr4 ,h>dman believ$ !m to be n less ?an #ejj feet deep4 ,! same obs]v] f\nd t !y c]ta9ly rea* a height ( #abj feet above ! sea1 & he 0 ( op9ion t 9 "s places _! height 0 n less ?an #adj feet4 ,! deposition ( /rata to ! dep? ( #cjj feet bel[ a level ( #abj feet above ! sea w\ld1 ( c\rse1 entirely fill up ,l\gh ,neagh1 & spread ov] a l>ge tract ( l[ gr\nd ar\nd x4 ,! pott]y-clays & lignites1 h[ev]1 appe> to be conf9$ to ! s\!rn half ( ! lake1 f :i* !y rise g5tly into ! l[ c\ntry ar\nd4 ,! di/ribution ( ^! deposits & _! extraord9>y v>iations 9 altitude1 z describ$ by ,mr4 ,h>dman1 pres5t great difficulties 9 ! attempt to reg>d !m z ! s$im5ts ( a ,plioc5e lake4 ,a m rec5t exam9ation ( ! gr\nd by ,mr4 ,clem5t ,reid ( ! ,geological ,survey has l$ t able obs]v] to believe t two totally diff]5t gr\ps ( /rata at ,l\gh ,neagh h be5 conf\nd$4 ,he notic$ ! ,mytilus-clay to be a d>k blue mass full ( d]iv$ b\ld]-clay /ones1 & yield+ ,mytilus edulis & se$s ( a s$ge4 ,?is deposit _c be ,plioc5e1 b mu/ be ( ,glacial or po/-,glacial age1 possibly contempor>y ) ! ,clyde b$s4 ,! junction ( ?is clay ) ! pipe-clays is n at pres5t se51 b ! li?ological contra/ betwe5 ! two gr\ps ( /rata is s /rong z to indicate _! indep5d5ce ( ea* o!r4 ,mr4 ,reid f\nd ! :ite1 r$ & mottl$ pipe-clays ) _! masses ( lignite to pres5t a /rong resemblance to ! ,bag%ot gr\p 9 ! ,t]ti>y s]ies4 ,x is possible1 z already sugge/$1 t ! pipe-clays & lignites may belong to ! s$im5t>y zone t sep>ates ! l[] & upp] basalts ( ,antrim4 ,at all ev5ts !y furni% no pro( ( any ,plioc5e lake1 & may n indicate m ?an a deep] "p ( ! depression 9 :i* ! tuffs1 lignites & iron-ore 7 laid d[n4 ,! exi/5ce ( ! ,mytilus-clay %[s t 9 ,glacial or po/-,glacial times ! valley ( ! ,bann 0 a /rait or fjord into :i* ! sea ent]$4 ,?ick masses ( drift h be5 laid d[n all r\nd & ov] ! depression n[ occupi$ by ,l\gh ,neagh1 insomu* t _h any old] lake exi/$ "h 9 ,glacial times1 x c\ld h>dly h escap$ be+ fill$ up4 ,! obs]v]1 :o f "o ( ! basalt-heights looks d[n ^u ! expanse ( ,l\gh ,neagh & ! broad peat-cov]$ pla9 t cont9ues ! level plat=m ( ! lake-surface d[n ! valley ( ! ,bann1 _c b be impress$ ) ! size ( ?is wide holl[ 9 ! he>t ( ! ,antrim plateau1 & ) ! evid5t cont9uity ( ! :ole depression f ! lake to ! sea4 ,if he be a geologi/1 he w be fur!r /ruck by ! fact t :ile ! ,*alk & o!r old] rocks appe> f "u ! basalt-esc>pm5ts all r\nd ! plateau1 at heights ( _m hundr$ feet above ! sea1 ! floor ( ?is wide holl[ is entirely cov]$ ) basalt4 ,_h ! depression be5 m]ely due to d5udation1 ! rocks t und]lie ! volcanic s]ies w\ld h be5 expos$ to view4 ,! base ( ! basalts :i*1 on ei!r side ( ! depression1 is (t5 m ?an #ajjj feet above ! sea-level1 s9ks bel[ t level 9 ! holl[ ( ! ,bann & ,l\gh ,neagh4 ,?is inequality ( position may h be5 p>tially br\ght ab\t by faults l ^? ar\nd ,l\gh ,neagh1 & may ?us h be5 begun long be=e ! ,glacial p]iod4 ,b x appe>s to me to be ma9ly due to a wide subsid5ce1 ( :i* ! axis ran 9 a ,n4,n4,w4 & ,s4,s4,e4 direction f ! pres5t coa/ up ! valley ( ! ,bann & ! bas9 ( ,l\gh ,neagh to beyond ,portad[n4 ,we may conceive t aft] ! cessation ( ! outfl[s ( basalt1 ! t]ritory ov]ly+ ! lava-res]voir t _h be5 empti$ w\ld t5d to subside1 p>tly by ruptures ( ! cru/ produc+ faults & p>tly by a d[nw>d movem5t ( a m g5]al k9d4 ,9 c\rse ( "t1 ^! di/urbances turn$ ! dra9age into ! holl[ n[ trav]s$ by ! ,bann4 ,d5udation w\ld necess>ily accompany !m1 & ! surface ( ! c\ntry w\ld be cont9ually erod$ & l[]$4 ,l\gh ,neagh has be5 c>efully s\nd$ by ! ,admiralty1 & its *>t af=ds mu* sugge/ive mat]ial = ! consid]ation ( ! geologi/4#dcf ,f ! s\nd+s !re giv5 x has long be5 kn[n t ! lake deep5s t[>ds its nor!rn end1 & atta9s a maximum dep? ( #ajb feet4 ,b x is n until we trace on ! *>t a s]ies ( cont\r-l9es = successive dep?s1 z %[n by ! s\nd+s1 t we realize ! rem>kable =m ( ! lake bottom4 ,we !n discov] t bel[ a dep? ( #ej feet a well-def9$ *annel ext5ds = r m ?an half ! l5g? ( ! lake4 ,?is *annel beg9s to be di/9ctly p]ceptible betwe5 ,kiltagh ,po9t & ,lang=d ,lodge4 ,x fir/ runs 9 a nor!rly c\rse on ! we/ side ( ! c5tre ( ! ,l\gh1 b :5 x comes into a l9e ) ,salt]a ,ca/le on ! we/]n %ore1 x :eels r\nd s z to con=m to ! curve ( ! ,antrim coa/-l9e1 :i* x foll[s nor?w>d until1 ab\t two miles f ! exit ( ! lake1 its outl9e ceases to be traceable on ! g5tly %elv+ bottom4 ,its total l5g? is ?us ab\t #ab miles4 ,footnote #dcf3 ,l\gh ,neagh survey$ & s\nd$ by ,lieut4 ,?omas ,graves1 ,r4,n4 ,!re c h>dly be any d\bt t ?is *annel is a =m] b$ ( ! ,riv] ,bann4 ,x occupies exactly ! position :i* t /ream w\ld take if ! lake 7 dra9$1 & its dep? & bread? correspond to ^? ( ! valley-bottom ( ! pres5t riv]4 ,if ?is conclusion be accept$1 "s important conclusions may be fur!r d$uc$ f x4 #a4 ,! pres5ce ( a =m] c\rse ( ! ,bann on ! bottom ( ,l\gh ,neagh proves ! lake to be mu* y\ng] ?an ! ,ice ,age4 ,! ?ick b\ld]-clays & ,glacial gravels :i* s encumb] ! c\ntry ar\nd & desc5d "u ! lake1 w\ld assur$ly h fill$ up ! riv]-*annel _h x exi/$ at ! "t ( _! deposition4 ,! *annel has obvi\sly be5 cut out ( ^! drifts s9ce ! ,glacial p]iod4 ,:5 ! erosion took place1 ! pres5t ,l\gh ,neagh c\ld n h exi/$1 b ! ,bann foll[$ a cont9u\s c\rse across ! pla9 :i* ! lake n[ cov]s4 ,! riv] probably ma9ta9$ its place = a long p]iod1 s z to be able to excavate s wide & deep a b$ 9 ! drifts1 if1 inde$1 x did n to "s ext5t sl[ly c>ve its b$ out ( ! und]ly+ basalts4 ,x mu/ be rememb]$ t s$im5t is be+ cont9ually p\r$ into ,l\gh ,neagh1 & t "s ( ! silt mu/ h accumulat$ 9 ! subm]g$ riv]-c\rse1 ?us less5+ its dep? & wid?4 ,t ! *annel %\ld /ill be s m>k$ may be us$ z an argum5t = ! comp>atively late date ( ! subsid5ce4 #b4 ,! subm]g$ riv]-c\rse is a cle> pro( ( subsid5ce4 ,! pres5t ,l\gh ,neagh _c be look$ ^u z a glacial lake =m$ by rock-erosion or by irregul> deposition ( drift4 ,its floor mu/ h be5 a l& surface :5 ! ,bann cut out its b$ ^u x4 ,! :ole area has sunk d[n1 ! dra9age has be5 arre/$1 & "s #bj miles ( ! c\rse ( ! ,bann are n[ "u a %eet ( %all[ wat]4 ,?is subsid5ce 0 n br\ght ab\t by faults4 ,x seems r to h result$ f a g5]al s9k+ ( ! gr\nd4 ,! movem5t 0 probably comp>atively rapid1 o!rwise ! riv]-c\rse w\ld h>dly h surviv$ s well4 #c4 ,^! inf]5ces1 bas$ ^u purely geological consid]ations1 h an int]e/+ be>+ ^u ! allusions to ! orig9 ( ,l\gh ,neagh conta9$ 9 "s anci5t hi/orical docum5ts4 ,v>i\s leg5ds h f an e>ly p]iod be5 h&$ d[n z to ! fir/ appe>ance ( ?is %eet ( wat]4 ,^! my?s1 ?\gh diff]+ 9 details1 agree 9 describ+ su* a sudd5 or rapid accumulation ( wat] z de/roy$ human life1 9 a di/rict :i* _h previ\sly be5 inhabit$ by man4 ,! e>lie/ records indicate t ! alleg$ cata/rophe took place 9 ! fir/ c5tury ( ! ,*ri/ian era4#dcg ,x appe>s to me n improbable t ! tradition1?us pres]v$ 9 ^! leg5ds1 may h _h its basis 9 ! actual di/urbance :i*1 on geological gr\nds1 c be %[n to h det]m9$ ! exi/5ce ( ,l\gh ,neagh4 ,?\gh ! ev5t may g back f> beyond ! fir/ c5tury1 !re c be no d\bt t1 9 a geological s5se1 x 0 "o ( ! mo/ rec5t topographical *anges :i* ! ,briti% ,isles h und]gone4 ,footnote #dcg3 ,= v]sions ( ! leg5ds1 see ,dr4 ,todd's ,iri% ,v]sion ( ! ,hi/oria ,britonum ( ,n5nius1 ,roy4 ,hi/1 & ,ar*ol4 ,assoc4 ,irel&2 ,dr4 ,reeves' ,ecclesia/ical ,antiquities ( ,d[n1 etc41 p4 #cgj2 ,mr4 ,j4 ,o',beirne ,cr[e's ,anci5t ,lake ,leg5ds ( ,irel&1 ,no4 #a 9 ,j\rn4 ,roy4 ,hi/4 & ,ar*ol4 ,assoc4 ,irel&1 vol4 i4 7#ahgj-ga71 p4 #id2 ,giraldus ,cambr5sis1 vol4 v4 cap4 ix4 p4 #ia--;de lacu magno miram orig9em hab5te4 ,moore's well-kn[n l9es embody ! popul> belief t r\nd t[]s & o!r build+s 7 subm]g$ by ! inundation4 ,?us ! ,antrim basalt-plateau1 9 addition to ! high int]e/ ( its volcanic hi/ory1 has ! additional claim to our att5tion t x has pres]v$1 m fully & cle>ly ?an any o!r ( ! plateaux1 ! evid5ce = ! late/ subt]ranean movem5ts t foll[$ ! long s]ies ( volcanic eruptions dur+ ,t]ti>y "t4 ,x conta9s ! record ( a po/-,glacial subsid5ce t gave bir? to ! l>ge/ lake 9 ,brita94 ii4 ,,dislocations ,?\gh ,i h n obs]v$ any features among ! ,t]ti>y basalt-plateaux ( ! ,briti% ,isles t c be comp>$ to ! rem>kable rifts & subsid5ces ( ,icel&1 x c be %[n t ^! piles ( volcanic mat]ial h und\bt$ly be5 fractur$1 & t portions ( !m h subsid$ along ! l9es ( dislocation4 ,c>eful exam9ation ( ! basalt-esc>pm5ts ( ! ,inn] ,hebrides discloses ! exi/5ce ( num]\s faults :i*1 ?\gh g5]ally ( small displacem5t1 nev]!less completely break ! cont9uity ( all ! rocks 9 a precipice ( #gjj or #ajjj feet 9 height4 ,n infrequ5tly su* dislocations give rise to clefts 9 ! cliffs4 ,"s good illu/rations ( ?is feature may be notic$ on ! nor? side ( ! isl& ( ,canna1 :]e ! precipice has be5 fissur$ by a s]ies ( dislocations1 hav+ a hade t[>ds ! we/ & a ?r[ :i* may 9 "s cases am\nt to ab\t #bj or #be feet4 ,! cumulative effect ( ?is sy/em ( fault+1 comb9$ ) a g5tle we/]ly dip1 is to br+ d[n to ! sea-level ! upp] b& ( conglom]ate :i* fur!r to ! ea/ lies at ! top ( ! cliff4 ,aga91 ! basalt-esc>pm5t on ! we/ side ( ,skye1 f ,dunvegan ,head to ,lo* ,eynort1 is trav]s$ by a s]ies ( small faults4 ,on ! ea/ side ( ,skye & 9 ,raasay1 a numb] ( faults1 "s ( !m hav+ p]haps a ?r[ ( sev]al hundr$ feet1 has be5 mapp$ by ,mr4 ,h4 ,b4 ,woodw>d4 ,! l>ge/ dislocation obs]v$ by me among ! basalt-plateaux ( ! ,inn] ,hebrides is t already ref]r$ to 7p4 #bji71 :i* runs at ! back ( ! ,morv5 outli]1 9 ! we/ ( ,argyll%ire1 f ! ,s\nd ( ,mull by ! head ( ,lo* ,al9e to ! m\? ( ,lo* ,sun>t1 along ! l9e ( valley t conta9s ! salt-wat] fjord ,lo* ,teacus & ! fre%-wat] lakes ,lo* ,dur9ema/ & ,lo* ,ari5as4 ,:ile ! ,cretace\s deposits & ! bottom ( _! ov]ly+ basalts rise b little above ! sea-level on ! s\?-we/ side ( ?is l9e1 !y are p]*$ z outli]s on hill-tops on ! nor?-ea/ side1 :]e !y rise to #acjj feet above ! sea4 ,! am\nt ( v]tical displacem5t "h probably exce$s #ajjj feet4 ,! fault runs 9 a nor?-we/]ly direction1 & has obvi\sly be5 ! guid+ influ5ce 9 ! erosion ( ! broad & deep valley :i* m>ks its c\rse at ! surface4 ,?is dislocation is only ! l>ge/ ( a numb] by :i* ! basalt-plateau has be5 brok5 9 ! di/rict ( ,morv54 ,_! effects are well %[n 9 ! outli] ( basalt :i* caps ,b5 ,iada91 :]e two p>allel faults br+ d[n ! lavas aga9/ ! plat=m ( s*i/s on :i* !y lie 7see ,fig4 #bff74 ,_m faults h be5 trac$ 9 ! ,antrim plateau1 & are repres5t$ on ! ,geological ,survey ,maps4 ,9 g5]al !y are ( comp>atively trifl+ displacem5t4 ,occasionally1 h[ev]1 !y am\nt to sev]al hundr$ feet1 z 9 ^? already ref]r$ to z occurr+ ne> ,ballyca/le & ar\nd ! s\!rn "p ( ! bas9 ( ,l\gh ,neagh4 ,to :at ext5t ! dislocations t trav]se ! ,briti% ,t]ti>y basalts are to be reg>d$ z comp>able to ^? :i* 9 ,icel& h be5 ref]r$ to subsid5ce caus$ by ! tapp+ & outfl[ ( ! l[] /ill liquid p>ts ( lava-%eets mu/ be matt] = fur!r inquiry4 ,s f> z my own obs]vations h yet gone1 ! faults d n seem explicable by any m]e sup]ficial action ( ! k9d suppos$4 ,:]e !y desc5d ?r\gh _m hundr$s ( feet ( successive %eets ( basalt1 & dislocate ! ,second>y =mations und]nea?1 !y mu/ obvi\sly h be5 produc$ by mu* m g5]al & deep-seat$ causes4 ,x is conceivable t1 if ^! dislocations took place dur+ ! volcanic p]iod1 !y broke up ! lava-pla9s into sections1 "s ( :i* sank d[n s z to leave a v]tical wall at ! surface on "o side ( ! r5t1 or ev5 to =m op5 gjs1 l ^? ( ,icel&4 ,b x is notewor?y t ! fissures1 :i* h be5 fill$ ) basalt & n[ appe> z dykes1 comp>atively seldom %[ any displacem5t 9 ! relative levels ( _! two sides4 ,9 ,icel&1 also1 ! great lava-emitt+ fissures seem to be 9 g5]al free f m>k$ displacem5ts ( t k9d4 ,illu/ration3 ,fig4 #chb4--,rev]s$ fault on ! ea/]n side ( ,sv91 ,f>oe ,isles4 ,! faults 9 ! ,inn] ,hebrides1 s f> z ,i h obs]v$1 are all normal1 & indicate no?+ m ?an g5tle subsid5ce4 ,b among ! ,f>oe ,isl&s ,i h come ^u sev]al in/ances ( rev]s$ faults1 :i*1 9 spite ( ! usually g5tle incl9ations ( ! basalts1 probably po9t to m vigor\s displacem5t )9 ! t]re/rial cru/4 ,on ! ea/ side ( ,sv9 a fault ) a l[ hade runs f sea-level up to ! top ( ! cliff1 a height ( sev]al hundr$ feet4 ,x has a d[n-?r[ ( a few y>ds1 b is a rev]s$ fault1 z w be se5 f ,fig4 #chb4 ,ano!r simil> in/ance may be notic$ on ! nor?-ea/ headl& ( ,s&1 :]e1 h[ev]1 on ! upca/ side1 ! basalts appe> z if !y _h be5 driv5 upw>d1 a portion ( !m hav+ be5 pu%$ up into a l[ ar* 7,fig4 #chc74 ,illu/ration3 ,fig4 #chc4--,rev]s$ fault on ! nor?-ea/ headl& ( ,s&1 ,f>oe ,isle4 ,:5 ! ,t]ti>y basalt-plateaux ( ! ,hebrides & ! ,f>oe ,isles come to be work$ out 9 detail1 _m examples ( dislocation w d\btless be discov]$4 ,we %all !n le>n m ( ! am\nt & effects ( ! t]re/rial di/urbances :i* h affect$ ,nor?-,we/]n ,europe s9ce old] ,t]ti>y "t4 ,9 ! meantime evid5ce en\gh has be5 adduc$ to prep>e u = pro(s ( v consid]able rec5t displacem5ts ev5 among regions ( cry/all9e s*i/s1 l t :i* has be5 disrupt$ by ! ,morv5 faults above allud$ to4 ,:ile ! /udy ( ! ,t]ti>y volcanic rocks demon/rates ! va/ g5]al d5udation ( ! c\ntry s9ce old] ,t]ti>y "t1 ! pro(s t ^! rocks h be5 fault$ acquire a special int]e/ 9 relation to ! orig9 & evolution ( ! topography ( ! region4 ,,*apt] ,l ,,effects ,,( ,,d5udation ,among ! m impressive lessons :i* ! basalt-plateaux ( ,nor?-,we/]n ,europe tea* ! geologi/1 ! enorm\s erosion ( ! surface ( ?is "p ( ! cont95tal area s9ce old] ,t]ti>y "t takes a =emo/ place4 ,he may be ready almo/ )\t "q to accept ! evid5ce adduc$ 9 fav\r ( a va/ am\nt ( d5udation among su* s(t & incoh]5t /rata z ^? ( ! old] ,t]ti>y =mations ( ! s\?-ea/ ( ,engl& or ! nor?-we/ ( ,france4 ,b he is h>dly prep>$ = ! pro(s :i* meet him among ! nor?-we/]n isles t su* ?ick masses ( solid volcanic rocks h be5 remov$ dur+ ! same geological int]val4 ,to ga9 "s idea ( ! am\nt ( ?is wa/e we mu/1 9 ! fir/ place1 picture to our m9ds ! ext5t ( gr\nd ov] :i* ! lavas 7 p\r$1 & ! dep? to :i* !y 7 pil$ ^u x4 ,?\gh we may nev] be able to asc]ta9 :e!r ! n[ isolat$ basalt-plateaux ( ,brita9 7 once unit$ into a cont9u\s pla9 ( lava1 we c be q c]ta9 t e "o ( ^! plateaux 0 =m]ly m ext5sive ?an x is n[1 = ea* ( !m pres5ts1 z its t]m9al edge1 a l9e ( wall =m$ by ! truncat$ ends ( horizontal basalt-%eets4 ,& !re seems no improbability 9 ! assumption t ! :ole ( ! great holl[ f ! c5tre ( ,antrim up to ! ,m9* 0 flood$ ) lavas :i* fl[$ f _m v5ts betwe5 ! hills ( anci5t cry/all9e rocks =m+ ! l9e ( ! ,out] ,hebrides on ! we/1 & ^? ( ! ma9l& ( ,scotl& on ! ea/4 ,x is c]ta9 t ! dep? to :i* "s p>ts ( ?is long holl[ 7 ov]fl[$ ) lava exce$$ #cjjj feet1 = m ?an t dep? ( rock c be %[n to h be5 9 "s places remov$4 ,! orig9al inequalities ( surface 7 buri$ "u ! volcanic mat]ials :i* 7 spread out 9 a va/ pla9 or s]ies ( pla9s1 l ^? t h be5 delug$ by mod]n eruptions 9 ,icel&4 ,ow+1 h[ev]1 to a g5]al b unequal movem5t ( subsid5ce1 ! lava-fields sank d[n "h & !re to1 p]haps1 an ext5t ( sev]al hundr$ feet1 s t ! old l&-surface on :i* !y began to be p\r$ out n[ lies 9 ^? places bel[ ! level ( ! sea4 ,i h %[n t ev5 dur+ ! volcanic p]iod1 :ile ! lavas 7 /ill fl[+ f "t to "t1 erosion 0 9 active progress ov] ! surface ( ! volcanic pla94 ,! records ( riv]-action 9 ,canna & ,s&ay1 & ! buri$ riv]-*annel ( ! ,scuir ( ,eigg1 prove t1 :ile eruptions /ill cont9u$1 riv]s desc5d+ f ! m\nta9s ( ! ,we/]n ,highl&s c>ri$ ! detritus ( ^! upl&s = _m miles across ! lava-fields1 swept away ! loose mat]ial ( volcanic cones1 & cut *annels = !mselves out ( ! black rugg$ floor ( basalt4 ,! erosion ?us e>ly begun has probably be5 c>ri$ on cont9u\sly ev] s9ce4 ,! pres5t /reams may be look$ ^u z practically ! same z ^? :i* 7 fl[+ 9 ! ,t]ti>y p]iod4 ,!re may h be5 slight *anges ( level1 oscillations bo? upw>d & d[nw>d 9 ! relative positions ( l& & sea1 & %ift+s ( ! wat]-c\rses to "o side or o!r2 b !re seems no reason to d\bt t ! exi/+ basalt-plateaux1 :i* 7 built up z t]re/rial areas1 h rema9$ l&-surfaces ) little int]mission ev] s9ce1 al?\gh _! l[] portions may h be5 9 l>ge measure subm]g$4 ,9 ! exi/+ valleys1 fjords & sea-/raits by :i* ^! plateaux h be5 s deeply & abundantly tr5*$1 we may recognize "s ( ! dra9age-l9es trac$ out by ! riv]s :i* fl[$ across ! volcanic pla9s4 ,! results a*iev$ by ?is prolong$ d5udation are ( ! mo/ /up5d\s k9d4 ,! orig9al lava-floor has be5 cut d[n into a fragm5t>y tablel&4 ,hundr$s ( feet ( solid rock h be5 remov$ f its g5]al surface4 ,outli]s ( x may be se5 scatt]$ ov] ! m\nta9s ( ,morv51 :5ce !y look into ! he>t ( ! ,highl&s4 ,o!rs cap ! hills ( ,rum1 :]e !y face ! op5 ,atlantic4 ,sev]al miles f ! ma9 body ( ! plateau 9 ,skye1 a solit>y remnant1 p]*$ on ! highe/ summit ( ,raasay1 be>s eloqu5t witness t ! basaltic tablel& once /ret*$ f> to ! ea/ ( its pres5t limits4 ,two l9es ( obs]vation & ( argum5t may be foll[$ 9 ! ef=t to demon/rate h[ great ! d5udation has be5 s9ce old] ,t]ti>y "t4 ,9 ! fir/ place1 !re is ! evid5ce ( ! level or ne>ly level %eets ( basalt t =m ! plateaux1 &1 9 ! second place1 !re is ! te/imony ( ! dykes1 sills & bosses by :i* ^! lavas h be5 disrupt$4 #a4 ,! /udy ( ! d5udation ( ! ,t]ti>y volcanic rocks ( ,nor?-,we/]n ,europe is mo/ satisfactorily begun by an attempt to measure ! m9imum am\nt ( wa/e :i* 9 c]ta9 places ! basalt-plateaux c be prov$ to h und]gone4 ,= ! purposes ( ?is /udy1 ! /ratification ( ! lavas & _! ne>ly horizontal1 or at lea/ v slightly di/urb$1 position af=d exceptional facilities4 ,amorph\s rocks1 su* z granites & gabbros1 or ev5 foliat$ masses l ! old gneisses & s*i/s1 may h be5 enorm\sly d5ud$4 ,_! m]e pres5ce at ! exi/+ surface may be tak5 z pro( ( su* wa/e1 yet !y furni% 9 !mselves no crit]ion by :i* ! am\nt ( remov$ mat]ial may be e/imat$4 ,b 9 ! case ( ! basalt-plateaux1 z 9 t ( horizontal s$im5t>y =mations1 ! successive l9es ( sup]position ( ! compon5t b$s ( ! :ole /ratigraphical s]ies supply admirable datum-l9es :i*1 on ! "o h&1 vividly impress ! imag9ation by ! demon/ration :i* !y af=d ( ! reality & magnitude ( ! d5udation1 &1 on ! o!r h&1 furni% a measure by :i* ! m9imum am\nt ( ?is d5udation may be actually comput$4 ,avail+ ourselves ( ?is k9d ( evid5ce x is easy to %[ t valleys _m miles long1 sev]al miles broad1 & f cre/ to bottom sev]al ?\s& feet deep1 h be5 excavat$ out ( ! basalt-plateaux s9ce ! close ( ! volcanic p]iod4 ,& if ?is conclusion c be demon/rat$ = ^! plateaux1 x mu/ obvi\sly apply equally to ! re/ ( ! c\ntry4 ,we ?us obta9 a mo/ important contribution to ! inve/igation ( ! orig9 & relative age ( ! pres5t topographical features ( ! surface ( ! l&4 ,let me give a few illu/rations ( ! nature ( ! inve/igation & ( ! results to :i* x leads4 ,?r\gh\t ! ,we/]n & ,f>oe ,isl&s ! level b>s ( basalt pres5t _! truncat$ ends 9 ! great esc>pm5t-cliffs :i* w9d mile aft] mile along _! picturesque coa/s4 ,:]e !y front ! op5 sea1 x is obvi\sly impossible to say h[ mu* fur!r seaw>d !y once ext5d$4 ,b :]e !y retire 9 fjords or sea-lo*s1 & sweep inl& into gl5s1 x is easy to measure ! di/ance f ! bottom ( ! erod$ holl[ to its b\nd+ wat]%$s1 & to e/imate ! am\nt ( mat]ial t has be5 worn out ( x4 ,! only unc]ta9ty 9 ?is computation arises f our inability to det]m9e to :at ext5t movem5ts ( subsid5ce may h come into play to aid 9 ! disappe>ance ( ! basalts4 ,:]e ! bottom ( ! lavas c be se5 at ! same level on ei!r side ( an inlet1 ) no evid5ce ( fault+1 or :]e a def9ite horizon 9 ! volcanic s]ies c be trac$ r\nd ! head ( a gl5 or sea-lo*1 ! influ5ce ( und]gr\nd movem5ts may be elim9at$4 ,! evid5ce ( va/ d5udation is always visible1 ! pro(s ( subsid5ce are mu* less frequ5tly obs]vable4 ,! isl& ( ,mull supplies _m /rik+ examples ( ! enorm\s wa/e ( ! basalt-plateau4 ,! ,s\nd ( ,mull1 = in/ance1 has be5 erod$ out ( ! volcanic s]ies = a di/ance ( #bj miles1 ) a mean bread? ( ab\t two miles4 ,f ! deepe/ "p ( ?is fjord to ! summit ( ! ,mull plateau is a v]tical height ( #cfjj feet4 ,! :ole ( ?is va/ excavation has tak5 place s9ce old] ,t]ti>y "t4 ,on ! opposite side ( ,mull ! holl[ ( ,lo* ,scrida9 has be5 erod$ to a mean dep? ( at lea/ #abjj feet bel[ ! av]age level ( ! surr\nd+ plateau1 ) a bread? ( r m ?an a mile4 ,! scatt]$ isl&s :i* lie to ! we/ ( ,mull tell ! same tale4 ,!y are all outli]s ( ! same basalt-plateau1 & h n only be5 greatly l[]$ by ! removal ( _! upp] lavas1 b h be5 sep>at$ by ! erosion ( long & deep holl[s betwe5 !m4 ,?us f ! summit ( ! ,gribon cliffs 9 ,mull to ! deepe/ "p ( ! sea-floor betwe5 t precipice & ! ,tre%ni% ,isles a v]tical dep? ( at lea/ #bjjj feet ( rock has be5 remov$ s9ce ! basalts ceas$ to be erupt$4 ,i h ref]r$ to ! impressive evid5ce ( d5udation display$ on ! we/ side ( ! isl& ( ,eigg4 ,! v]tical di/ance f ! summit ( ! ,eigg plateau to ! bottom ( ! subm>9e valley betwe5 ?is isl& & ,rum is ab\t #aejj feet1 b z t summit lies bel[ ! orig9al surface ( ! lava-field1 ! dep? ( rock :i* has be5 remov$ mu/ exce$ #aejj feet4 ,we ?us le>n t s9ce ! close ( ! volcanic p]iod ! holl[ betwe5 ! isl&s ( ,eigg & ,rum has be5 erod$ to ?is great dep?4 ,/ill m /rik+ is ! evid5ce ( enorm\s wa/e pres5t$ by ! ,f>oe ,isl&s4 ,! cliffs !re are l(ti] & b>]1 & ! fjords h be5 cut m deeply & precipit\sly out ( ! basalt-plateau4 ,i %all nev] =get ! fir/ impression made on my m9d :5 ! d5se curta9 ( mi/ )9 :i* ,i _h approa*$ ! s\!rn end ( ! ar*ipelago rapidly cle>$ away1 & ! sunlit slopes & precipices ( ,sud]1 ! two ,dimons1 ,sku & ,s&1 rose out ( a deep blue sea4 ,ea* isl& %[$ its prolongation ( ! same long level l9es ( rock-t]race4 ,! eye at once seiz$ on ^! features z ! dom9ant elem5t 9 ! geology & ! topography1 = !y reveal$ at a glance ! true /ructure ( ! isl&s1 & gave a measure ( ! am\nt & irregul>ity ( ! erosion ( ! orig9al basalt-plateau4 ,& ?is fir/ impression ( /up5d\s degradation only deep5$ z "o advanc$ fur!r nor? into ! m m\nta9\s gr\p ( isl&s4 ,probably n[h]e else 9 ,europe is ! pot5cy ( d5udation z a factor 9 ! evolution ( topographical features s m>vell\sly & in/ructively display$ z among ! nor?-ea/]n memb]s ( ! ,f>oe gr\p4 ,avail+ ourselves ( ! datum-l9es suppli$ by ! ne>ly level b>s ( basalt1 we easily p]ceive t 9 _m p>ts ( ! ,f>oe ,isles ! am\nt ( volcanic mat]ial left beh9d1 /up5d\s ?\gh x be1 is less ?an ! am\nt :i* has be5 remov$4 ,?us ! isl& ( ,kals is m]ely a long n>r[ ridge sep>at+ two broad valleys :i* are n[ occupi$ by fjords4 ,! mat]ial c>v$ out ( ^! valleys w\ld make sev]al isl&s z l>ge z ,kals4 ,aga91 ! l(ty precipice ( ,myl+ ,head1 #bbfj feet high1 built up ( b$d$ basalts f ! summit to bel[ sea-level1 faces ! nor?-we/]n ,atlantic1 & ! sea rapidly deep5s 9 front ( x to ! surface ( ! subm>9e ridge #bjj to #cjj feet bel[4 ,! truncat$ ends ( ! va/ pile ( basalt-%eets :i* =m t l(tie/ sea-wall ( ,europe be>s te/imony to ! colossal d5udation :i* has swept away all ( ! volcanic plateau t once ext5d$ fur!r t[>ds ! we/4 ,nev]!less1 enorm\s z has be5 ! wa/e ( ?is plateau ( ! ,f>oe ,isl&s1 we may /ill trace "s ( its t]re/rial features t date back probably to ! volcanic p]iod4 ,ev5 m di/9ctly1 p]haps1 ?an among ! ,we/]n ,isles ( ,scotl&1 we may recognize ! position ( ! orig9al valleys1 & trace "s ( ! ma9 dra9age l9es ( ! area :5 x =m$ a wide & cont9u\s tract ( l&4 ,a l9e ( wat]%$ c be foll[$ 9 a s\?-we/]ly direction f ! ea/ side ( ,vid]1 across ,bor to ! c5tre ( ,o/]1 & !nce by ! ,sund across ,/rom & ,vaag4 ,f ?is l9e ! fjords & valleys div]ge t[>ds ! nor?-we/ & s\?-ea/4 ,!re c h>dly be any d\bt t on ! :ole ?is l9e corresponds ) ! g5]al tr5d ( ! wat]-p>t+ at ! "t :5 ! ,t]ti>y /reams 7 fl[+ ov] ! /ill cont9u\s volcanic pla94 ,consid]able depression ( ! :ole region has s9ce !n s5t ! sea up ! l[] & wid] valleys1 conv]t+ !m into fjords1 & isolat+ _! int]v5+ ridges into isl&s4 ,! topography ( ! ,f>oe ,isl&s seems to me em95tly des]v+ ( c>eful /udy 9 ! light ( its geological orig94 ,!re is assur$ly no o!r region 9 ,europe :]e ! int]e/+ problems pres5t$ by ?is subject c\ld be /udi$ s easily1 :]e ! geological /ructure is ?r\gh\t s simple1 :]e ! comb9$ influ5ces ( ! atmosph]e & ( ! sea c\ld be s admirably work$ out & di/+ui%$1 & :]e ! imag9ation1 k9dl$ to en?usiasm by ! contemplation ( noble sc5]y1 c\ld be s con/antly & imp]i\sly controll$ by ! accurate obs]vation ( asc]ta9able fact4 #b4 ,impressive & easily compreh5d$ z are ! pro(s ( d5udation suppli$ by ! basalts ( ! plateaux1 !y are p]haps to a geological eye less ov]:elm+ ?an ^? furni%$ by ! eruptive rocks :i* h be5 inject$ into ^! plateaux4 ,9 ! case ( at lea/ ! basic intrusions1 we may reasonably inf] t !y assum$ _! pres5t position "u a great] or less dep? ( ov]ly+ rock :i* has s9ce be5 remov$4 ,:51 !re=e1 !y are f\nd at or above ! summits ( ! plateaux1 !y demon/rate t a va/ am\nt ( mat]ial has be5 remov$ f ^! summits4 ,! argum5t f ! position ( ! dykes has already be5 en=c$4 ,x is absolutely c]ta9 t valleys sev]al ?\s& feet deep mu/ h be5 excavat$ s9ce ^! dykes 7 erupt$1 = _h su* valleys exi/$ at ! "t :5 ! dykes 7 inject$ across _! site1 ! molt5 rock1 in/ead ( asc5d+ to ! tops ( ! surr\nd+ m\nta9s1 w\ld obvi\sly h ru%$ =? ov] ! valley-bottoms4 ,i h %[n t ?is reason+ applies n m]ely to ! volcanic di/ricts1 b to ! :ole surface ( ! c\ntry )9 ! region ( dykes4 ,?us ! upl&s ( ,s\!rn ,scotl&1 & wide areas 9 ! ,s\!rn & ,we/]n ,highl&s1 c be prov$ to h _h gl5s cut out ( _! mass to a dep? ( hundr$s ( feet s9ce ! ,t]ti>y volcanic p]iod4 ,n less conv9c+ is ! evid5ce af=d$ by ! great eruptive masses ( gabbro4 ,we h se5 t ^! complex accumulations ( sills1 dykes1 & bosses include rocks s co>se 9 gra9 z to %[ t !y mu/ h consolidat$ at "s consid]able dep?1 b t !y n[ appe> 9 hill-gr\ps #bjjj to #cjjj feet 9 height1 ! :ole ( ! orig9al basaltic cov] hav+ be5 /ripp$ (f f !m4 ,b ^! gabbro hills h be5 9 turn trav]s$ up to ! v cre/s by lat] basalt-dykes1 :i* ?us supply additional pro( t ! erosion "h has be5 /up5d\s4 ,! granophyre bosses tell ! same tale4 ,?\gh1 l ! domite ,puys ( ,auv]gne1 !y may /ill reta91 9 _! conical =ms1 indications ( ! orig9al %apes :i* _! compon5t mat]ial assum$ at ! "t ( its protrusion1 we may be confid5t t _! exi/+ surfaces h be5 rea*$ aft] ! removal ( mu* rock :i* once lay above !m4 ,?is inf]5ce is confirm$ by ! fact t ^! eruptive bosses h be5 invad$ by a y\ng] sy/em ( dykes4 ,! black ribs ( basalt :i* may be trac$ along _! pale declivities1 :i* cross ! gl5s t h be5 erod$ 9 !m & :i* m\nt up to _! v cre/s1 prove t s9ce ! late/ manife/ations ( volcanic en]gy 9 ! ,we/ ( ,scotl&1 ext5sive *anges 9 ! topography ( ! l& h be5 effect$ by ! op]ation ( ! subrial ag5ts ( degradation4 ,s mu* = :at c be demon/rat$4 ,b h[ mu* m may1 ) ! highe/ probability1 be inf]r$6 ,! orig9al limits ( ! plateaux are unkn[n4 ,! waves ( ! wide ,atlantic n[ roll ov] _m a squ>e league ( ! old lava-pla9s1 & wide tracts ( ! isl&s & ! ma9l& f :i* ! basalt has be5 entirely /ripp$1 or :]e x rema9s only 9 scatt]$ outli]s1 7 once deeply buri$ "u piles ( lava-%eets4 ,x w\ld probably be no exagg]ation to affirm t ov] ! ,briti% area1 z well z ov] ! ,f>oe ,isles1 ! am\nt ( ,t]ti>y volcanic rock t n[ rema9s1 l>ge z x is1 falls %ort 9 am\nt ( :at has be5 remov$4 ,! geologi/ :o has made himself famili> ) ! effects ( d5udation 9 o!r ,t]ti>y volcanic di/ricts1 su* z ,c5tral ,france1 ,saxony & ,bohemia1 w be prep>$ = almo/ any conceivable am\nt ( erosion among ! f> old] volcanic s]ies ( ! nor?-we/ ( ,europe4 ,to ! /ud5t ( ! orig9 ( ! exi/+ topography ( ! l& !re is a pr(\nd int]e/ 9 ! demon/ration :i* ^! volcanic rocks supply ( ! va/ *anges :i* ! t]re/rial surface has und]gone )9 a p]iod geologically s rec5t z old] ,t]ti>y "t4 ,:51 on ! "o h&1 he f9ds himself m & m re/rict$ 9 8 dem&s = "t by ! confid5t ass]tions ( ! physici/ t all ! ph5om5a ( geological hi/ory mu/ h be5 compris$ )9 a few millions ( ye>s1 & :51 on ! o!r h&1 he wat*es ! seem+ly feeble & t>dy op]ations ( ! =ces ( d5udation & s$im5tation :i* h play$ ! *ief p>ts 9 t hi/ory1 he may well be excus$ if sometimes he is apt to despair ( ev] reconcil+ ! facts :i* he obs]ves ) ! physical d$uctions t are some:at dogmatically br\ght =w>d 9 opposition to 8 int]pretation ( !m4 ,he may feel sure t 8 facts _c be ga9said1 & he may be unable to f9d any o!r way ( compreh5d+ !m save by ! admission t !y necessitate a lib]al all[ance ( "t4 ,yet he may n feel himself to be 9 a position to (f] any valid objections to ! argum5ts f physical consid]ations t w\ld s s]i\sly abridge ! l5g? ( "t :i* geology requires4 ,9 ^! circum/ances x is "s satisfaction to be provid$ ) def9ite measurem5ts ( ! am\nt ( geological *ange :i* has be5 effect$ )9 a limit$ & relatively rec5t p]iod ( "t4 ,?is *ange has result$ f ! op]ation ( ! same ag5ts by :i* x is /ill be+ c>ri$ on4 ,no break 9 ! hi/ory c be detect$4 ,!re is n ! lea/ reason to suppose t ! ag5ts ( d5udation & s$im5tation h1 dur+ ! p]iod 9 "q1 diff]$ 9 _! rate ( work+4 ,_! activity at ! pres5t "t is probably nei!r great] nor less ?an x 0 !n4 ,if1 !re=e1 dur+ s rec5t an int]val su* a /up5d\s am\nt ( mat]ial has be5 worn away f ! surface ( ! l& & deposit$ on ! sea-floor z ! ,t]ti>y volcanic rocks demon/rate1 ! geologi/ may surely contemplate )\t misgiv+ ! lapse ( "t requir$ = ! completion ( old] geological revolutions4 ,he may oppose to ! argum5ts ( ! physici/ ! measurem5ts & computations :i* he himself makes f data :i* are at lea/ z reliable z ! po/ulates :]eon ^! argum5ts are bas$4 ,! rate at :i* d5udation & s$im5tation are n[ tak+ place has be5 measur$ ) tol]able accuracy1 & a fair av]age = x has be5 obta9$4 ,:atev] may be ma9ta9$ z to ?is rate 9 e>ly geological ages1 !re c be no s]i\s opposition to its be+ tak5 z fairly con/ant s9ce old] ,t]ti>y "t4 ,we are ?us provid$ ) data = e/imat+ ! m9imum am\nt ( "t t c h elaps$ s9ce ! volcanic plateaux began to be d5ud$4 ,b z no relic rema9s ( ! orig9al upp] surface ( ^? plateaux1 & z we are consequ5tly ignorant ( h[ mu* rock has be5 remov$ f _! highe/ surviv+ outli]s1 x is obvi\s t su* e/imates are m likely to err 9 und]/at+ ?an ov]/at+ ! am\nt ( "t requir$4 ,x w\ld be beyond ! scope ( ! pres5t volume to ent] fully into ! measurem5ts & calculations requir$ = ! adequate treatm5t ( ?is subject4 ,i w m]ely illu/rate my argum5t by aga9 tak+ a few data f ! plateau ( ,mull4 ,! orig9al height ( ?is plateau is %[n by ! outli] ( ,b5 ,m to h be5 at lea/ #cbjj feet4 ,if to ?is figure we add ! portion ( ! basalt-gr\p subm]g$ "u ! sea ! height w probably be increas$ by sev]al hundr$ feet4 ,b let u take #cjjj feet z a mod]ate computation = ! av]age ?ickness ( ! volcanic s]ies "h at ! close ( ! plateau-p]iod4 ,until a numb] ( sections h be5 c>efully plott$ f ! ,ordnance ,maps1 9 ord] to asc]ta9 ) approximate accuracy ! av]age height ( ! pres5t surface ( ! ,mull basaltic plateau1 mak+ due all[ance = ! va/ erosion ( ! ,s\nd ( ,mull & ! num]\s gl5s & sea-lo*s t trav]se ! isl&1 any e/imate :i* may be (f]$ z to ?is av]age mu/ be m]ely provisional4 ,if1 9 ! meantime1 we suppose ! pres5t mean level ( ! plateau to be #ajjj feet above ! sea1 ! diff]5ce betwe5 ?is am\nt & ! assum$ orig9al height w be #bjjj feet4 ,if1 fur!r1 we take ! pres5t av]age rate ( degradation ( ! ,mull plateau to be #a_/fjjj ( a foot 9 a ye>1 :i* has be5 %[n to be probably a fair e/imate1 !n ! "t requir$ = ! l[]+ ( ! ,mull plateau f its orig9al to its pres5t av]age level am\nts to twelve millions ( ye>s4 ,yet ?is p]iod1 va/ ?\gh x be1 does n c>ry u back ev5 z f> z ! beg9n+ ( ,t]ti>y "t4 99 99 99 99 99 ,9 conclud+ ?is l5g!n$ discussion ( ! ,t]ti>y volcanic hi/ory ( ,brita91 ,i may1 p]haps1 usefully add a brief summ>y ( ! lead+ features ( ! long record4 ,! region )9 :i* volcanic activity display$ itself dur+ old] ,t]ti>y "t 9 ! ,briti% ,isles1 if our e/imate ( its area is re/rict$ to ^? p>ts ( ! c\ntry :]e igne\s rocks1 probably ( t age1 n[ appe> at ! surface1 embraces ! ,nor? ( ,engl& & ( ,irel&1 ! s\!rn half & ! we/ coa/ ( ,scotl&--a total area ( m ?an #dj1jjj squ>e miles4 ,ov] t ext5sive region volcanic ph5om5a 7 display$ dur+ an enorm\sly protract$ int]val ( geological "t4 ,! e>lie/ beg9n+s ( di/urbance may possibly h />t$ 9 ! ,eoc5e1 & ! f9al manife/ations may n h ceas$ until ! ,mioc5e p]iod4 ,s prolong$ 0 ! duration ( ! eruptions1 t enorm\s topographical *anges f d5udation1 & probably also consid]able v>iation 9 ! fauna & flora1 alike ( l& & sea1 may h be5 effect$4 ,ow+ to "s cause :i* has n yet 9 ?is relation be5 inve/igat$1 b :i* is probably ref]able to secul> t]re/rial contraction1 ! volcanic region und]w5t elevation1 :ile1 at ! same "t1 a va/ subt]ranean lake or sea ( molt5 rock exi/$ und]nea? x4 ,enorm\s horizontal t5sion ?us arose1 & at la/ ! /ret*$ t]re/rial cru/ gave way4 ,a sy/em ( approximately p>allel fissures op5$ 9 x1 hav+ a g5]al direction t[>ds nor?-we/4 ,! rapid & simultane\s production ( su* a gigantic s]ies ( r5ts mu/ h giv5 rise to e>?quakes ( enorm\s magnitude & de/ructive =ce4 ,! great majority ( ! fractures1 d\btless1 did n rea* to ! surface ( ! gr\nd1 ?\gh probably n a few did s4 ,su* 0 ! pot5cy ( ?is developm5t ( t]re/rial en]gy1 t ! fissures ran ?r\gh ! mo/ v>i$ k9ds ( rocks & ! mo/ complicat$ geological /ructures1 cross+ ev5 e>li] l9es ( p[]ful dislocation1 & yet reta9+ _! direction & p>allelism = sometimes #ej or #ajj miles4 ,into ! fissures ?us =m$ ! molt5 magma f und]nea? 0 =c$ = _m hundr$s or ev5 ?\s&s ( feet above ! surface ( ! subt]ranean lava-res]voir4 ,solidify+ betwe5 ! fissure walls1 x =m$ ! cr[d ( basic dykes t /& out z ! mo/ widespread & di/9ctive feature ( ! volcanic region4 ,:]e ! fissures rea*$ ! surface or ne> to x1 ! molt5 rock w\ld seek relief by egress 9 /reams ( lava4 ,?is probably occurr$ 9 _m places f :i* subsequ5t d5udation has remov$ all ve/ige ( sup]ficial volcanic manife/ations4 ,b1 9 ! great range ( basalt-plateaux1 f ,antrim nor?w>ds ?r\gh ! *a9 ( ! ,inn] ,hebrides1 !re are /ill left abundant rema9s ( ! surface-outfl[s4 ,l ! mod]n lavas ( ,icel&1 ! molt5 mat]ial probably fl[$ out sometimes f ! op5 fissures1 sometimes f v5ts =m$ along ! *asms4 ,aft] ! convulsions ceas$ :i* produc$ ! e>lie/ dykes1 ! communication t _h be5 e/abli%$ betwe5 ! magma-res]voir und]nea? & ! air above w\ld be ma9ta9$1 & repeat$ eruptions might take place1 ei!r f ! orig9al fissures & v5ts or f o!rs aft]w>ds op5$ by ! volcanic en]gy4 ,z 9 ! mod]n eruptions ( ,icel&1 new fissures are successively op5$ ?r\gh ! old] lava-%eets1 s 9 ! ,t]ti>y volcanic areas1 r5ew$ ruptures ( ! e>?'s cru/ all[$ lat] dykes to be =m$4 ,! basalt-plateaux are trav]s$ by su* dykes1 ev5 up to _! highe/ %eets4 ,x is impossible to say h[ (t5 ! process ( dyke-mak+ may h be5 repeat$4 ,n improbably x recurr$ aga9 & aga9 dur+ ! build+ ( ! basalt-plateaux1 & we "k t x 0 r5ew$ ev5 aft] ! protrusion ( ! granophyre bosses :i* m>k "o ( ! late/ phases ( volcanism 9 ! region4 ,= a protract$ geological p]iod1 ) long int]vals ( quiesc5ce1 v>i\s basic lavas 7basalts1 dol]ites1 etc471 ) occasionally "s ( int]m$iate composition 7&esites1 tra*ytes71 & p]haps 9 ,antrim acid rhyolites1 fl[$ out f fissures & v5ts until !y _h fill$ up ! holl[s ( ! great valley1 :i* !n /ret*$ f ! s\? ( ,antrim nor?w>ds betwe5 ! we/ coa/ ( ,scotl& & ! *a9 ( ! ,out] ,hebrides4 ,9 "s places ! accumulat$ pile ( ^! ejections ev5 n[ exce$s #cjjj feet 9 ?ickness1 b we _c tell h[ mu* mat]ial has be5 b>$ away f its top by d5udation4 ,! volcanic dis*>ges consi/$ mo/ly ( lava1 fragm5t>y mat]ials be+ comp>atively insignificant 9 am\nt & local 9 orig91 ?\gh lay]s ( f9e tuff & basalt-breccias occur 9 all ! plateaux4 ,none ( ! erupt$ mat]ials ?ick5 t[>ds any c5tres t might be tak5 to m>k volcanoes ( ! type ( ,vesuvius or ,etna4 ,on ! contr>y1 ! p]si/5t flatness & uni=mity ( ! volcanic s]ies1 & ! ?9n+ out ( ! sep>ate b$s 9 diff]5t directions1 %[ t ! lavas issu$ f _m po9ts all ov] ! region4 ,! positions ( "s ( ! actual v5ts c /ill be asc]ta9$4 ,!y are n[ fill$ sometimes ) dol]ite1 sometimes ) co>se agglom]ate4 ,! surface ov] :i* ! lava fl[$ seems to h be5 ma9ly t]re/rial4 ,"h & !re1 betwe5 ! successive %eets ( basalt1 ! leaves1 /ems1 & fruit ( l&-plants1 sometimes 9 mo/ p]fect pres]vation1 may be obs]v$1 toge!r ) ! rema9s ( insects & fre%-wat] fi%4 ,di/9ct relics ( old riv]-*annels c be recogniz$ :i* h be5 buri$ "u /reams ( lava4 ,among ! deposits left by ^! /reams ! upp]mo/ lay]s are commonly d>k ) decay$ vegetation1 :ile lay]s ( coal are f\nd "h & !re betwe5 ! basalts4 ,z ! pile ( erupt$ mat]ials gradually ?ick5$1 & ! subt]ranean en]gy possibly grew feebl]1 ! asc5d+ magma 0 =c$ betwe5 ! lay]s ( s$im5t>y /rata und]nea? ! basalts1 or betwe5 ^! /rata & ! ov]ly+ volcanic s]ies1 or along any o!r plane ( weakness 9 ! t]re/rial cru/4 ,9 ?is way arose ! multitud9\s sills or intrusive %eets4 ,:5 ! great volcanic plateaux _h be5 built up to a ?ickness ( sev]al ?\s& feet1 ano!r rem>kable episode 9 ! hi/ory occurr$4 ,at c]ta9 po9ts l>ge bodies ( co>sely cry/all9e basic rocks 7 pu%$ into & ?r\gh ! plateaux-basalts1 uprais+ !m 9 dome-%ap$ elevations1 & ultimately solidify+ z dol]ites1 gabbros1 troctolites1 picrites1 etc4 ,!re is reason to believe t ! po9ts ( extravasation ( ^! mat]ials 7 ma9ly det]m9$ by ! positions ( ! l>g] or m closely clu/]$ v5ts ( ! plateau-p]iod1 :]e po9ts ( weakness consequ5tly exi/$ 9 ! t]re/rial cru/4 ,ris+ z huge bosses ?r\gh su* weak places1 ! gabbros & associat$ rocks rais$ up ! ov]ly+ b$d$ basalts1 & =c$ !mselves betwe5 !m1 =m+ ?us a fr+e ( f9]-gra9$ intrusive sills & ve9s ar\nd ! c5tral b&$ & amorph\s masses ( m co>sely cry/all9e mat]ial4 ,:e!r1 9 any ( ^! va/ domes ( upheaval1 ! summit 0 disrupt$1 s z to all[ ! basic intrusion to fl[ out z lava at ! surface1 _c n[ be told1 ow+ to enorm\s subsequ5t d5udation4 ,! next *apt] 9 ! *ronicle %[s u t probably long aft] ! eruption ( ! gabbros1 :5 possibly all outw>d symptom ( volcanic action _h ceas$1 a r5ew$ outbreak ( subt]ranean activity gave rise to ! protrusion ( ano!r & :olly diff]5t class ( mat]ials4 ,?is "t ! rocks 7 ( a m>k$ly acid type4 ,!y includ$ v>ieties t range f obsidians1 pit*/ones1 fl9ty felsites & rhyolites1 ?r\gh porphyries & granophyres1 into comp\nds :i* _c be class$ "u any o!r "n ?an granite4 ,^! masses likewise avail$ !mselves ( old] v5ts 9 ! plateaux1 & broke ?r\gh !m4 ,!y n[ =m huge conical hills1 :i*1 9 _! out] aspect1 & ev5 to "s ext5t 9 _! inn] /ructure1 recall ! tra*ytic puys ( ,auv]gne4 ,b ! granophyres n only asc5d$ ?r\gh ! basalt-plateaux & ! gabbro-bosses2 !y s5t into ^! rocks a network ( ve9s1 pu%$ _! way 9 huge %eets or sills betwe5 ! /rata bel[1 & actually incorporat$ a consid]able proportion ( ! basic mat]ials into _! own sub/ance4 ,ar\nd ! bosses ( gabbro & granophyre1 ! b$d$ basalts h und]gone consid]able contact-metamorphism4 ,! gabbro & granophyre bosses ( ! ,inn] ,hebrides demon/rate ) s+ul> =ce h[ unreliable petrographical *>act]s are z a te/ ( ! relative age ( rocks4 ,no "o1 look+ at h&-specim5s ( ^! rocks1 or ev5 /udy+ !m 9 ! field1 w\ld at fir/ suspect !m to be ( ,t]ti>y date4 ,!y closely resemble rocks ( simil> k9ds 9 ,palozoic & ev5 ,ar*an =mations4 ,yet1 ( _! late appe>ance 9 geological "t1 !re _c be any possibility ( d\bt4 ,aft] ! uprise ( ! granophyre1 & ! injection ( ! network ( felsitic ve9s1 !re came once m a p]iod ( t]re/rial convulsion1 l t ( ! e>lie/ basic dykes1 b ( less int5sity4 ,aga91 ! cru/ ( ! e>? ov] ! volcanic region 0 pu%$ upw>d & r5t op5 by ano!r sy/em ( p>allel fissures4 ,aga91 f a res]voir or bas9 ( basic lava und]nea?1 molt5 rock 0 =c$ upw>ds into ! r5ts1 & ?us ano!r sy/em ( basic dykes 0 =m$4 ,^! dykes are f\nd cross+ ^? ( e>li] date1 & ris+ ?r\gh ! o!r volcanic rocks4 ,!y trav]se ! plateau-basalts f bottom to top2 !y climb to ! summits ( ! gabbro m\nta9s1 & !y ev5 pursue _! undeviat+ c\rse ov] ! huge domes ( granophyre4 ,no pro( has yet be5 f\nd t f any ( ^! dykes !re 0 a sup]ficial outfl[ ( lava4 ,b s great has be5 ! subsequ5t d5udation ( ! areas1 t su* outfl[s might q well h tak5 place1 & h subsequ5tly be5 de/roy$4 ,:e!r ^! basic dykes 7 ! la/ manife/ation ( volcanic en]gy 9 our region _c yet be decid$ly affirm$4 ,s f> z ! evid5ce at pres5t goes1 !y are possibly old] ?an ano!r s]ies ( acid ve9s & dykes 7pit*/one1 felsite1 & granophyre71 :i* are f\nd at _m po9ts f ,antrim to ! f> end ( ! ,inn] ,hebrides4 ,^! protrusions trav]se e o!r memb] ( ! volcanic s]ies1 except "s ( ! y\nge/ basic dykes1 & d n appe> to be !mselves cut by any4 ,s9ce ! close ( ! volcanic p]iod consid]able di/urbance ( ! basalt-plateaux has tak5 place4 ,! :ole volcanic region has subsid$1 "s di/ricts hav+ sunk m ?an o!rs4 ,9 ,brita9 ! mo/ /rik+ evid5ce ( su* depression is suppli$ by ! bas9 ( ,l\gh ,neagh4 ,b ?r\gh\t ! ,inn] ,hebrides mu* ( ! l[] portion ( ! t]re/rial lava-plateaux is n[ bel[ sea-level4 ,9 ! ,f>oe ,isl&s & 9 ,icel& ! subsid5ce has be5 /ill m m>k$4 ,dislocations1 also1 sometimes am\nt+ to m ?an a ?\s& feet ( displacem5t1 h occurr$ among ! volcanic masses4 ,! b$d$ basalts1 orig9ally on ! :ole ne>ly flat1 h ?us be5 brok5 up into l>ge blocks ( c\ntry :]e9 ! %eets are n[ incl9$ 9 v>i\s directions4 ,"o ( ! mo/ important lessons taught by ! ,t]ti>y volcanic s]ies ( ! nor?-we/ ( ,europe is ! ext5t ( ! d5udation ( ! l& s9ce ! close ( ! volcanic p]iod4 ,! horizontal or g5tly incl9$ lay]s ( b$d+ among ! basalts af=d datum-l9es f :i* ! m9imum am\nt ( mat]ial remov$ may be measur$4 ,z a reasonable e/imate x may be inf]r$ t 9 ! case ( ! ,mull plateau1 = example1 ! av]age am\nt by :i* its surface has be5 l[]$ s9ce ! close ( ! volcanic p]iod _c be less ?an #bjjj feet4 ,if ! rate ( l[]+ ( ! l&-surface 9 we/]n ,europe by subrial d5udation be tak5 z #a_/fjjj ( a foot 9 a ye>1 !n ! lapse ( "t requir$ = ! degradation ( ! ,mull plateau mu/ am\nt to ab\t twelve millions ( ye>s4 ,"s su* int]val has !re=e elaps$ s9ce ! la/ ,t]ti>y volcanoes became ext9ct4 ,,*apt] ,,li ,,summ>y ,,& ,,g5]al ,,d$uctions ,! =ego+ *apt]s comprise a connect$ n>rative ( ! hi/ory ( volcanic action 9 ! area ( ! ,briti% ,isles dur+ ! va/ succession ( ages f ! e>ly ,ar*an dawn d[n to ! late/ eruptions ( ,t]ti>y "t4 ,9 ?is f9al *apt] ,i propose to pres5t a brief summ>y ( ! facts ( l>ge/ import & wide/ int]e/ :i* ?is protract$ hi/ory has plac$ be=e u1 toge!r ) a /atem5t ( d$uctions :i* may be drawn f !m reg>d+ ! nature & progress ( volcanism 9 ! evolution ( ! globe4 #a4 ,among ! broad features :i* soone/ arre/ att5tion 9 su* a survey is ! geographical position ( ! !atre ( ?is volcanic activity4 ,9 ! di/ribution ( volcanoes at ! pres5t "t we are famili> ) _! t5d5cy to range !mselves along cont95tal bord]s or 9 oceanic isl&s4 ,! volcanic en]gy s conspicu\s 9 ! geological hi/ory ( ,brita9 has %[n itself along ! we/]n or ,atlantic m>g9 ( ! ,european cont95t4 ,:5 ! eruptions h n be5 actually on ! l& itself1 !y h tak5 place )9 ! %all[ tracts ne> ! l&1 :]e ! lavas & tuffs h be5 int]/ratifi$ ) s$im5ts d]iv$ f ! adjac5t coa/s4 ,moreov] ! volcanic rocks 9 ,brita9 are rang$ along ! greate/ l5g? ( ! gr\p ( isl&s1 9 a g5]al nor? & s\? l9e1 f ! s\? ( ,devon%ire to ! f> ,%etl&s4 ,x is on ! we/]n side ( ! c\ntry t !y occur4 ,ea/ ( a l9e drawn f ,b]wick by ,leice/] to ,exet]1 al?\gh ! geological =mations1 rang+ f ! ,c>bonif]\s ,lime/one to ! late/ ,plei/oc5e deposits1 are !re abundantly expos$ to view1 !y include no contemporane\s volcanic rocks4 #b4 ,a second & /ill m rem>kable feature 9 ! geological hi/ory ( ,we/]n ,europe is ! p]si/5ce ( volcanic activity along ! site ( ! ,briti% ,isles4 ,evid5ce has be5 br\ght =w>d 9 ^! volumes t f ! primeval "t vaguely t]m$ ,ar*an1 onw>d to t ( ! old] ,t]ti>y clays & s&s ( ! s\?-ea/ ( ,engl&--t is to say1 ?r\gh by f> ! l>ge/ "p ( geological hi/ory1 z *ronicl$ 9 ! /ratifi$ cru/ ( ! globe--?is long /rip ( t]ritory cont9u$ to be int]mitt5tly a !atre ( volcanic action4 ,e great division ( ,palozoic "t 0 m>k$ by volcanic eruptions1 sometimes ov] tracts hundr$s ( squ>e miles 9 area & on a colossal scale4 ,aft] a long p]iod ( quiesc5ce dur+ ! ,mesozoic ages1 ! r5ew$ outbreak ( volcanic en]gy 9 old] ,t]ti>y "t1 s m>k$ ov] ! we/]n half ( ,europe1 rea*$ its maximum ( developm5t along ! ,atlantic bord]1 f ! nor? ( ,engl& & ,irel& ?r\gh ! *a9 ( ! ,inn] ,hebrides to ! ,f>oe ,isl&s1 ,icel& & ,gre5l&4 #c4 ,n only has !re be5 a rem>kable p]si/5ce ( volcanic activity ov] ! comp>atively limit$ area ( ! ,briti% ,isles1 view$ z a :ole1 b if we exam9e ! diff]5t p>ts ( ?is area we p]ceive t _m ( !m1 ( relatively re/rict$ ext5t1 h be5 ! sites ( a recrudesc5ce ( volcanic action1 aga9 & aga91 ?r\gh a va/ succession ( geological p]iods4 ,:ile ! :ole region has be5 9 diff]5t qu>t]s & at diff]5t times affect$1 !re h be5 di/ricts :]e ! volcanic fires h be5 rek9dl$ aft] long int]vals ( quiesc5ce1 ! new v5ts be+ op5$ among or ne> to ! sites ( e>li] volcanoes4 ,9 ! s\?-we/ ( ,engl&1 = example1 ! ,middle ,devonian tuffs & diabases 7 succe$$ 9 ! ,c>bonif]\s p]iod by ! eruptions ( ! ,culm-measures1 & 9 ! v same tracts came la/ ( all ! lavas & tuffs ( ! ,p]mian conglom]ates4 ,/ill m a/oni%+ is ! record ( volcanic en]gy 9 ! s\? ( ,scotl&1 :]e1 )9 a space ( n _m hundr$ squ>e miles1 !re are ! *ronicles ( ! ,ar5ig1 ,ll&eilo & ,bala eruptions ( ! ,s\!rn ,upl&s1 ! huge piles ( lavas & tuffs ( ! ,l[] ,old ,r$ ,s&/one1 ! long succession ( ! plateaux & !n ( ! puys ( ! ,c>bonif]\s p]iod1 ! gr\ps ( tuff-cones ( ! ,p]mian p]iod1 &1 la/ly1 ! num]\s dykes connect$ ) ! ,t]ti>y volcanoes4 ,:ile "s portions ( ! region h be5 specially liable to exhibitions ( volcanic action1 o!rs h cont9u\sly escap$4 ,"s ( ^! hor/s1 or /ation>y & unaffect$ blocks ( c\ntry1 h be5 surr\nd$ by or h ris5 close to ! bord]s ( ?is volcanic di/rict1 yet h ma9ta9$ _! immunity ?r\gh a long s]ies ( ages4 ,?us ! ,c5tral ,highl&s ( ,scotl&1 ?\gh !y 7 flank$ on ! s\? & s\?-we/ by ! active volcanoes ( ! ,old ,r$ ,s&/one1 & aga9 on ! s\? by ^? ( ,c>bonif]\s "t1 _h no v5ts op5$ on _! surface aft] ! metamorphism ( _! s*i/s4 ,/ill m /rik+ p]haps is ! immunity ( ! ,s\!rn ,upl&s4 ,?\gh !y 7 9 l>ge measure surr\nd$ by ! volcanoes ( ! ,l[] ,old ,r$ ,s&/one1 !n by ^? ( ! ,calcif]\s ,s&/ones & ,c>bonif]\s ,lime/one1 & ?\gh !y look$ d[n on ! ,p]mian eruptions ( ,ayr%ire & ,ni?sdale1 :i* spread /reams ( lava & %[]s ( a% along _! flanks1 ^! hills =m$ a solid block t seems to h resi/$ p]=ation by ! volcanic funnels4 ,aga91 ! tracts cov]$ ) ,c>bonif]\s ,lime/one 9 ,engl& & ,irel& almo/ entirely escap$ f invasion by volcanic eruptions4 ,we ?us le>n t ev5 )9 comp>atively re/rict$ regions "s portions ( ! t]re/rial cru/ h be5 areas ( weakness1 liable to s]ve aga9 & aga9 z l9es ( escape = volcanic en]gy1 :ile close to !m o!r portions ( great] solidity h be5 p]si/5tly left intact4 #d4 ,! sites ( volcanic v5ts 9 all ! geological sy/ems :]e9 !y occur 9 ,brita9 h n usually be5 det]m9$ by any obvi\s /ructure 9 ! rocks n[ visible4 ,!y comp>atively seldom dep5d on asc]ta9able l9es ( fault1 ev5 :5 faults1 probably already exi/5t1 occur 9 _! ne> neighb\rhood4 ,?is indep5d5ce1 to :i*1 h[ev]1 !re are occasional m>k$ exceptions1 comes out m p>ticul>ly 9 ! coal-fields pi]c$ by v5ts1 = m9+ op]ations h !re reveal$ ! positions ( _m m faults ?an c be trac$ at ! surface4 ,if ! sites ( ! v5ts h be5 fix$ by dislocations or l9es ( weakness 9 ! t]re/rial cru/1 ^! mu/ g5]ally lie bel[ ! =mations n[ visible at ! surface4 ,!re is "o /rik+ connection betwe5 ! sites ( ! v5ts & anci5t topographical features to :i* frequ5t ref]5ce has be5 made 9 ! =ego+ *apt]s4 ,all ?r\gh ! long volcanic hi/ory1 z f> back z su* features c be trac$1 we see t orifices ( dis*>ge = ! erupt$ mat]ials h be5 op5$ along l[ gr\nds & valleys r ?an on ridges & hills4 ,! great c5tral holl[ ( ! ,scotti% midl&s 0 a depression ev5 z long ago z ! "t ( ! ,l[] ,old ,r$ ,s&/one1 & ?\gh x has probably be5 sev]al times s9ce !n fill$ up1 & m or less completely effac$1 its anci5t features h be5 p>tially reveal$ by ext5sive d5udation4 ,?is va/ depression1 #dj miles broad1 betwe5 ! ,highl& m\nta9s on ! "o side & ! ,s\!rn ,upl&s on ! o!r1 0 ! *ief c5tre ( volcanic activity 9 we/]n ,europe dur+ ! latt] half ( ,palozoic "t4 ,! v5ts ( ! ,old ,r$ ,s&/one1 ,c>bonif]\s & ,p]mian s]ies are scatt]$ all ov] x1 b few or none ( !m are to be f\nd on ! high gr\nds t b\nd x4 ,aga91 9 ,t]ti>y "t1 ! great outp\r+ ( lava took place 9 ! holl[ t lay betwe5 ! ridge ( ! ,out] ,hebrides & ! ma9l& ( ,scotl&4 ,?is wide & long tract ( l[ gr\nd 0 buri$ "u upw>ds ( #cjjj feet ( lava & tuff1 b ^! mat]ials 7 erupt$ f fissures & v5ts )9 its own bord] & n f ! m\nta9s on ei!r side4 ,b p]haps ! mo/ conspicu\s example ( any 9 :i* ! v5ts keep to ! valleys is t suppli$ by ! ,p]mian necks ( ,ni?sdale & ! neighb\r+ gl5s4 ,^! depressions are z old z ,p]mian1 & ev5 z ,c>bonif]\s "t1 b !y appe> to be entirely holl[s ( erosion2 at lea/ !y h yield$ no evid5ce t _! direction has be5 det]m9$ by l9es ( fault4 ,! *a9 ( v5ts c be foll[$ f ! l[l&s ( ,ayr%ire up to ! base ( ! ,s\!rn ,upl&s1 d[n ! wide valley cut by ! ,ni? 9 ^! hills & up "s ( ! tribut>y valleys1 & ?\gh ! volcanoes cont9u$ = "s "t 9 vigor\s eruption1 n a trace ( any contempor>y v5t has yet be5 met ) on ! surr\nd+ hills4 ,:ile ! position ( volcanic v5ts 9 l9es ( valley may be g5]ally due to guid+ l9es ( fissure 9 ! cru/ und]nea?1 ei!r )9 or bel[ ! rocks visible at ! surface1 !re may sometimes be conditions 9 :i* o!r dom9ant causes come into play4 ,! curi\s co9cid5ce betwe5 v>iations 9 ! upp] limit ( dykes & inequalities 9 ! configuration ( ! ov]ly+ gr\nd1 sugge/ t :]e ! subt]ranean magma has asc5d$ to )9 a comp>atively %ort di/ance f ! surface1 a diff]5ce ( a few hundr$s or ?\s&s ( feet 9 ! dep? ( ov]ly+ rock1 su* z ! diff]5ce ( height betwe5 ! bottom ( a valley & ! tops ( ! adjac5t hills1 may det]m9e ! pa? ( escape = ! magma ?r\gh ! lea/ ?ickness ( ov]>*+ ro(4 #e4 ,volcanic ph5om5a _c be reg>d$ z a m]e isolat$ & incid5tal feature 9 ! physics ( ! globe4 ,dur+ ! %ort "t )9 :i* man has be5 obs]v+ ! op]ations ( exi/+ volcanoes1 he has h>dly yet _h suffici5t opportunity ( wat*+ h[ f> !y c be correlat$ ) o!r t]re/rial movem5ts4 ,nor1 :5 he endeav\rs to trace "s su* connection among ! records ( ! geological pa/1 has he yet collect$ mat]ials en\gh to furni% a suffici5tly broad & firm basis ( comp>ison4 ,"o =midable ob/acle is pres5t$ by ! difficulty 9 det]m9+ *ronological equival5ts 9 sep>at$ gr\ps ( rock4 ,geologi/s h tri$ to discov] :e!r ! volcanoes ( "s p>ticul> p]iod or region 7 9 any way connect$ ) su* geological *anges z ext5sive plication1 dislocations ( ! cru/1 or elevation ( m\nta9-*a9s4 ,9 reg>d to ! volcanic hi/ory ( ,brita91 v>i\s possible relations ( ?is k9d obvi\sly sugge/ !mselves4 ,?us ! division ( geological "t compris$ )9 ! ,l[] ,silurian p]iod 0 und\bt$ly an int]val ( consid]able t]re/rial di/urbance 9 we/]n ,europe4 ,! uncon=mabilities & ov]laps 9 ! s]ies ( =mations belong+ to t p]iod1 ! frequ5t conglom]ates1 ! great & (t5 rapid *anges 9 ! ?ickness & li?ological *>act]s ( ! /rata1 all po9t to in/ability ( l&-surface & sea-floor4 ,dur+ ^! oscillations a prolong$ & widespread s]ies ( volcanic eruptions took place4 ,! volcanic manife/ations began 9 ,cambrian "t & cont9u$ 9 int]mitt5t activity till t[>ds ! close ( ! deposition ( ! ,l[] ,silurian =mations4 ,x is c]ta9ly a significant fact t ! ,upp] ,silurian deposits1 9 _! li?ological *>act]s1 pres5t a /rong contra/ to ^? t prec$$ !m4 ,!y po9t1 on ! :ole1 to quiet s$im5tation1 dur+ an int]val ( comp>ative calm 9 ! t]re/rial cru/4 ,) ?is evid5ce ( tranquillity !re is1 ov] almo/ ! :ole ( ! ,briti% ,isles1 an entire abs5ce ( any trace ( r5ew$ volcanic activity4 ,) ! exception ( ! ,d+le lavas & tuffs1 9 ! extreme we/ ( ,irel&1 n a s+le und\bt$ in/ance is yet kn[n ( an ,upp] ,silurian volcano4 ,aft] ! deposition ( ! ,upp] ,silurian rocks an int]val ( great t]re/rial di/urbance ensu$1 & ^! rocks ov] a l>ge "p ( ,brita9 7 int5sely plicat$ & cru%$4 ,! movem5ts1 cont9u$ into ! p]iod ( ! ,l[] ,old ,r$ ,s&/one1 71 9 _! lat] /ages1 accompani$ or1 at lea/1 foll[$ by ! va/ outp\r+s ( lava :i* n[ cov] s mu* ( ! tracts ( ,old ,r$ ,s&/one 9 ,scotl& & ,irel&4#dch ,footnote #dch3 ,trans4 ,geol4 ,soc4 ,ed94 vol4 ii4 "p iii4 7#ahgd74 ,9 proportion z ! volcanic en]gy 0 vigor\s1 widespread & long-cont9u$1 we may expect x to h be5 connect$ ) important t]re/rial movem5ts affect+ ext5sive regions ( ! e>?4 ,! ,t]ti>y volcanic hi/ory seems to af=d a rem>kable in/ance ( ?is connection4 ,a wide area ( ! ,european cont95t is dott$ ov] ) old c5tres ( volcanic activity :i* 7 9 eruption at successive epo*s ?r\gh\t ! ,t]ti>y p]iod4 ,( all ^! c5tres ! mo/ important 0 t ( ! nor?-we/]n basalt-plateaux1 :]e floods ( lava 7 dis*>g$ ov] _m ?\s& squ>e miles f ,irel& to ,gre5l&4 ,! geological date ( ^! outp\r+s probably co9cides ) ! la/ great orographic movem5ts t gave to ! m\nta9-*a9s ( ,europe _! late/ elevation & dim5sions4 ,b )\t ent]+ into :at mu/ be = ! pres5t a field ( speculation1 we c be assur$ ( "o important fact 9 ! connection ( anci5t volcanoes ) movem5ts ( ! t]re/rial cru/4 ,a /udy ( ! records ( volcanic action 9 ,brita9 proves beyond dispute t ! volcanoes ( pa/ "t h be5 active on areas ( ! e>?'s surface t 7 s9k+ & n ris+4 ,we usually associate volcanic action ) elevation r ?an subsid5ce1 & !re are c]ta9ly abundant pro(s ( su* elevation ar\nd active or rec5tly ext9ct volcanoes4 ,_m ( ! active v5ts ( ! pres5t "t1 l ,vesuvius & ,etna1 began ) subm>9e eruptions & h be5 gradually uprais$ into l&4 ,x may be1 h[ev]1 t su* uprise is m]ely a tempor>y incid5t1 & t if we c\ld survey ! :ole geological p]iod ( :i* human hi/ory *ronicles s small a "p1 we might f9d t subsid5ce1 & n upheaval1 is ultimately ! rule ov] volcanic areas4 ,be ?is z x may1 !re c be no "q t ) ! "o solit>y exception ( ! ,t]ti>y volcanoes1 :i* 7 t]re/rial & n subm>9e1 all ! ,briti% v5ts 7 c>ri$ d[n & ev5tually buri$ "u aque\s s$im5ts4 ,ev5 ! ,t]ti>y lava-fields h 9 _m places sunk d[n bel[ sea-level s9ce _! eruptions ceas$4 ,t !re are any ,palozoic volcanic rocks n[ visible at ! surface is obvi\sly due to subsequ5t movem5ts n imm$iately connect$ ) _! orig9al conditions ( eruption1 & to gigantic d5udation4 ,! am\nt ( subsid5ce :i* foll[$ on a volcanic episode 0 sometimes enorm\s1 ev5 )9 ! same geological p]iod1 z "o may see by obs]v+ ! prodigi\s piles ( s$im5t>y mat]ial heap$ ov] ! lavas & tuffs ( ,ar5ig "t1 or ov] ^? ( ! ,l[] ,old ,r$ ,s&/one4 ,i d n wi% to ma9ta9 t ! d[nw>d movem5t 0 necess>ily a consequ5ce ( volcanic ejections1 = we "k t x took place ov] tracts remote f c5tres ( eruption4 ,b ,i h sometimes ask$ myself :e!r x 0 n possibly increas$ z a sequel to vigor\s volcanic action2 :e!r1 = in/ance1 ! great dep? ( ! ,palozoic s$im5t>y rocks 9 "s regions1 z comp>$ ) _! feeble developm5t 9 o!rs1 may n h be5 due to an accel]ation ( subsid5ce consequ5t ^u volcanic action4 #f4 ,a review ( ! geological hi/ory ( ,brita9 _c b impress ! geologi/ ) a conviction ( ! ess5tial uni=mity ( volcanism 9 its manife/ations s9ce ! e>ly beg9n+s ( geological "t4 ,! composition & /ructure ( ! mat]ials erupt$ f ! int]ior h rema9$ ) b little *ange4 ,! mann] 9 :i* ^! mat]ials h be5 dis*>g$ has likewise p]si/$ f ! remote/ p]iods4 ,! ?ree mod]n types ( ,vesuvian cones1 puys & fissure-eruptions c be se5 to h play$ _! p>ts 9 ! pa/ z !y d to-day4 ,among ! e>lie/ igne\s masses ( :i* ! relative geological date c be fix$ are ! dykes :i* =m s /rik+ a sy/em among ! ,ar*an rocks ( ! nor?-we/1 & %[ h[ f> back ! mod]n type ( volcanic fissures & dykes c be trac$4 ,no relic1 inde$1 has surviv$ ( any lavas t may h fl[$ out f ^! anci5t fissures1 b s f> z reg>ds und]gr\nd /ructure1 ! type is ess5tially ! same z t ( ! ,t]ti>y & mod]n ,icel&ic lava-fields4 ,! e>ly ,palozoic volcanoes =m$ cones ( lava & tuff comp>able to ^? ( su* v5ts z ,vesuvius & ,etna4 ,9 ! ,lake ,di/rict ! pile ( mat]ial eject$ dur+ ,l[] ,silurian "t 0 at lea/ #hjjj or #ijjj feet ?ick4 ,9 ! ,old ,r$ ,s&/one bas9s ( ,c5tral ,scotl& !re 7 m ?an "o mass ( lavas & tuffs ?ick] ?an ^? ( ,vesuvius4 ,! puys ( ! lat] half ( ,palozoic "t closely resembl$ _! ,t]ti>y successors 9 ,c5tral ,france1 ! ,eifel1 & ! ,phlegran ,fields4 ,nor1 z reg>ds ext5t & vig\r1 did ! eruptions ( ! geological pa/ diff] 9 any important respect f ^? ( ! pres5t "t4 ,!re is assur$ly no evid5ce t volcanic en]gy has gradually wan$ s9ce ! dawn ( geological hi/ory4 ,! late/ eruptions ( ,nor?-,we/]n ,europe1 =m+ ! ,t]ti>y basalt-plateaux1 f> exce$$ 9 area1 & possibly also 9 bulk ( mat]ial dis*>g$1 all ! eruptions t _h prec$$ !m 9 ! geological record4 #g4 ,nev]!less1 :ile ! ,t]ti>y eruptions %[$ no dim9ution ( vig\r1 x is und\bt$ly true t ! volcanic en]gy has n manife/$ itself 9 a uni=m way s9ce ! beg9n+ ( geological "t4 ,!re h be5 p]iods ( maximum activity foll[$ by o!rs ( less5$ =ce4 ,?us if we take a broad view ( ! g5]al features ( volcanic action dur+ ! ,palozoic ages 9 ,brita91 we see cle> evid5ce ( a gradual dim9ution 9 its vig\r4 ,! widespread outp\r+s ( lava & tuff 9 ! ,silurian p]iod 9 ,engl&1 ,wales1 ,scotl& & ,irel& 7 succe$$ by ! some:at dim9i%$1 ?\gh /ill important1 eruptions ( ! ,l[] ,old ,r$ ,s&/one bas9s4 ,! latt] 7 foll[$ by ! /ill less5$ outfl[s ( ! ,c>bonif]\s plateaux1 :i* 9 turn 7 succe$$ by ! yet feebl] & m localiz$ eruptions ( ! ,c>bonif]\s puys1 ! :ole prolong$ volcanic succession end+ 9 ! small scatt]$ v5ts ( ! ,p]mian p]iod4 ,!re 7 ( c\rse oscillations ( relative en]gy dur+ ?is hi/ory1 "s ( ! maxima & m9ima be+ ( consid]able mom5t4 ,b ?\gh progress t[>ds ext9ction 0 n regul> & uni=m1 x 0 a dom9ant feature ( ! ph5om5a4 #h4 ,! ,p]mian volcanoes 7 ! la/ ( ! long ,palozoic s]ies1 &1 s f> z we yet "k1 ! :ole ( ! ,mesozoic p]iods )9 ! area ( ,brita9 7 absolutely unbrok5 by a s+le volcanic eruption4 ,! *ronological value ( ?is enorm\s int]val ( quiesc5ce may1 p]haps1 nev] be asc]ta9able1 b ! int]val mu/ assur$ly cov] a l>ge "p ( geological "t4 ,x 0 an era ( geological calm1 dur+ :i* ! ,triassic1 ,jurassic & ,cretace\s =mations 7 sl[ly accumulat$ ov] ! l>g] "p ( ,europe4 ,! /ratigraphical quietude 0 n inde$ unbrok54 ,! widespread subsid5ce ( ! sea-bottom 0 int]rupt$ "h & !re by important upheavals1 & consid]able geographical *anges 7 9 process ( "t accompli%$4 ,b1 save 9 "o or two widely sep>at$ areas ( ,europe1 !re 7 no active volcanoes ov] ! :ole cont95t4#dci ,"h aga9 ! sc>city or abs5ce ( int]calat$ volcanic rocks is 9 h>mony ) ! g5]al /ratigraphy ( ! =mations4 ,footnote #dci3 ,! ,triassic eruptions ( ,pr$azzo & ,monzoni 7 important1 & traces ( o!rs are said to occur 9 ! ,cretace\s sy/em 9 ,portugal & ,silesia4 #i4 ,aft] ! prodigi\s int]val repres5t$ by ! :ole ( ! ,mesozoic & ! e>li] "p ( ! ,t]ti>y =mations1 a "t ( di/urbance arose once m1 & ! great basalt-floods ( ! nor?-we/ 7 p\r$ =?4 ,evid5ce has be5 adduc$ 9 ! =ego+ *apt]s t ?is late/ volcanic p]iod 0 "o ( va/ duration2 t x 0 m>k$ by long int]vals ( quiesc5ce1 & by repeat$ r5ewals ( volcanic en]gy4 ,yet ov] ! area ( ,brita9 ! :ole ( its manife/ations 7 probably compris$ )9 ! e>li] 7,oligoc5e & p]haps e>ly ,mioc5e7 "p ( old] ,t]ti>y "t4 ,s9ce its eruptions ceas$1 ano!r int]val ( pr(\nd quiesc5ce has succe$$1 :i* /ill cont9ues4 ,b ?is int]val is almo/ c]ta9ly ( less duration ?an t :i* elaps$ betwe5 ! ,palozoic & ,t]ti>y outbur/s4 ,9 o!r words1 remote z ! date ( ^! ,t]ti>y volcanoes appe>s to be f our own day1 x comes mu* ne>] to u ?an did ! era ( ! la/ ,p]mian eruptions to ! e>lie/ ( ! ,t]ti>y s]ies4 #aj4 ,by ! dissection :i* prolong$ d5udation has effect$ among ! old volcanic c5tres ( ,brita91 mat]ials are suppli$ = /udy+ ! sequ5ce ( ev5ts f ! beg9n+ to ! end ( a volcanic p]iod4 ,^! ev5ts h g5]ally foll[$ ! same tol]ably well-def9$ ord]4 ,9 ! case ( fissure-eruptions1 r5ts =m$ 9 ! cru/ ( ! e>? & communicat+ ) ! surface h all[$ lava to rise & fl[ out above gr\nd1 ei!r f ! lips ( ! fissures or f v5ts op5$ along ! l9es ( *asm4 ,! ?\s&s ( p>allel dykes 9 ,brita9 rema9 z evid5ce ( ?is mode ( ! asc5t ( ! molt5 magma4 ,l9es ( l>ge cones ( ! ,vesuvian type may be presum$ to h ris5 along guid+ fissures 9 ! t]re/rial cru/4 ,b x is evid5t f a /udy ( ! ,briti% examples t ! exi/5ce ( a fissure 9 ! visible "p ( ! cru/ is n always necess>y = ! production ( a volcanic v5t4 ,9 hundr$s ( in/ances1 communication f ! int]nal magma to ! surface 0 effect$ by successive explosions1 :i* f9ally blew out an orifice at ! surface ) no visible relation to any fissures or dykes4 ,( c\rse1 b5ea? ! =mations t n[ =m ! surface1 & ?r\gh :i* ! necks rise1 !re may be l9es ( fault or weakness 9 old] rocks :i* we _c see4 ,b1 9 :at c be actually exam9$1 v5ts h commonly be5 drill$ ?r\gh rocks indep5d5tly ( faults4 ,! dis*>ge ( explosive vap\rs 0 sometimes ! fir/ & only ef=t ( volcanic en]gy4 ,g5]ally1 h[ev]1 fragm5t>y volcanic mat]ials 7 eject$1 or1 if ! eruption 0 m vigor\s1 lava 0 p\r$ out4 ,9 a va/ numb] ( cases1 especially 9 ! lat] ages ( ,palozoic "t1 only a%es 7 project$1 & cones ( tuff 7 =m$4 ,9 ! e>li] ages1 on ! o!r h&1 !re 0 a mu* l>g] proportion ( lava expell$4 ,t[>ds ! close ( a volcanic p]iod1 ! v5ts 7 gradually *ok$ up ) ! fragm5t>y mat]ials t 7 eject$ f & fell back into !m4 ,occasionally1 dur+ ! process ( ext9ction1 an explosion might /ill occur & cle> ! *imney1 s z to all[ ( ! uprise ( a column ( molt5 rock :i* solidifi$ !re2 or ! sides ( ! crat]1 z well z ( ! cav]n\s funnel und]nea?1 fell 9 & fill$ up ! passage4 ,heat$ vap\rs sometimes cont9u$ to asc5d ?r\gh ! debris 9 ! v5t1 & to produce on x a m>k$ metamorphism4 ,!re seems to h be5 commonly a contraction & subsid5ce ( ! mat]ials 9 ! v5ts1 ) a consequ5t dragg+ d[n or sagg+ ( ! rocks imm$iately outside1 :i* are ?us made to plunge /eeply t[>ds ! necks4 ,:5 ! v5ts 7 plugg$ up by ! consolidation ( fragm5t>y matt] or ! uprise ( lava 9 !m1 ! f9al ef=ts ( ! volcanoes l$ to ! intrusion ( sills & dykes1 n only into ! rocks b5ea? ! volcanic %eets1 b also1 9 _m in/ances1 into at lea/ ! old] p>ts ( ! %eets !mselves4 ,^! subt]ranean manife/ations ( volcanic action may be recogniz$ 9 almo/ e di/rict4 ,!y v>y greatly 9 ! degree to :i* !y are develop$4 ,sometimes1 z 9 ! ,cad] ,idris1 ,ar5ig & ,sn[don regions1 !y atta9 consid]able importance1 alike z reg>ds ! numb] & ?ickness ( ! %eets4 ,9 o!r cases1 !y are exhibit$ on s small a scale t !y might be ov]look$1 z 9 ! tract ( ,c>bonif]\s puy-eruptions 9 ! nor? ( ,ayr%ire4 ,b !y are s g5]ally pres5t z to =m a rem>kably *>act]i/ic feature ( ! volcanic activity ( ea* geological p]iod f ! e>lie/ "t to ! late/4 ,! basic %eets 9 ! ,dalradian s]ies ( ,scotl& display e>ly & colossal examples4 ,all ?r\gh ! successive eruptive p]iods ( ,palozoic "t1 sills are f\nd z accompanim5ts ( sup]ficial ejections4 ,! ,t]ti>y basalt-plateaux supply num]\s & gigantic examples ( intrud$ %eets4 ,t]ti>y cones ( ,vesuvian type are n f\nd 9 ,brita91 b :]e on ! cont95t !y h be5 suffici5tly laid op5 by d5udation1 !y pres5t sometimes an a/oni%+ s]ies ( sills4 ,z a /rik+ illu/ration ( ?is /ructure ref]5ce may be made to ! %eets ( tra*yte t h be5 inject$ betwe5 & h m>moriz$ ! ,cretace\s /rata on :i* ,monte ,v5da /&s1 among ! ,euganean ,hills4#ddj ,footnote #ddj3 ,g4 vom ,ra?1 ,zeits*4 ,deuts*4 ,geol4 ,gesells*41 xvi4 7#ahfd71 p4 #dfa4 ,e4 ,suess1 ,sitzungsb]4 k4 ,akad4 ,wi541 lxxi4 7#ahge71 p4 #g2 ,antlitz d] ,erde1 vol4 i4 p4 #aic4 ,e4 ,rey]1 ,die ,eugane51 #ahgg4 ,?is volcano is fur!r ref]r$ to1 po/ea1 p4 #dgg4 ,x is obvi\s t ! "t ( intrusion ( ! sills _c be precisely det]m9$4 ,!y 7 n likely to be inject$ at an epo* :5 ! volcanic magma c\ld f9d ready egress to ! surface4 ,t !y did n arise be=e su* egress 0 obta9$ may be inf]r$ f _! petrographical *>act]s1 :i* are usually ^? ( ! lat] & n ( ! e>li] outfl[s ( ! magma2 & f ! fact t !y n only lie among ! rocks bel[ ! volcanic s]ies1 b int]sect ! l[] p>ts ( t s]ies1 sometimes ev5 ! high] p>ts4 ,we may !re=e1 ) e probability1 reg>d ! sills z among ! clos+ phases ( a volcanic p]iod4 ,z ! lavas & tuffs ( ea* volcanic p]iod are int]calat$ among ! successive geological =mations1 a def9ite beg9n+ & end to ! p]iod are /ratigraphically fix$4 ,we see exactly :]e 9 ! s$im5t>y s]ies ! fir/ %[]s ( a%es fell1 & :]e ! la/ m+l$ ) ! ord9>y s& & mud ( ! sea-door4 ,! same record %[s t ! volcanic accumulations 7 f9ally wa%$ d[n1 t !y subsid$ ) ! re/ ( ! gr\nd ar\nd !m1 & t usually !y 7 buri$ "u ov]ly+ con=mable s$im5t>y deposits4 ,?us cones ( a%es & lava :i* may h be5 sev]al ?\s& feet high completely disappe>$4 #aj4 ,a consid]ation ( ! di/ribution ( ! volcanic rocks 9 "t %[s n only h[ s+ul>ly uni=m ! c\rse ( volcanic activity has be51 b t !re is no evid5ce ( ! cessation ( any ( ! broad] petrographical types dur+ geological hi/ory4 ,q z mu* v>iety may be obs]v$ among ! erupt$ mat]ials ( ,t]ti>y "t 9 ,brita9 z among ^? ( ! e>ly ages1 :5 ! e>? 0 y\ng] & its volcanic vig\r might be suppos$ to h be5 great] & m v>i$ ?an x is n[4 ,! table on ! foll[+ page w make ^! features at once app>5t4 ,f ?is table x w be se5 t :ile "s ( ! acid rocks h n always be5 extrud$1 ! basic masses h play$ _! "p 9 e volcanic p]iod4 #aa4 ,a /udy ( ! volcanic products ( a long s]ies ( eruptions )9 ! same geographical region may be expect$ to ?r[ light on ! *anges t take place dur+ ! c\rse ( ages 9 ! "* ( ! int]nal molt5 magma4 ,9 a =m] *apt] 7vol4 i4 p4 #bg7 ref]5ce 0 made to ! subject ( volcanic cycles & to ! sequ5ce1 obs]v$ 9 v>i\s widely sep>at$ p>ts ( ! _w1 among ! mat]ials erupt$ f bel[4 ,allusion 0 likewise made 9 a lat] *apt] 7vol4 i4 p4 #ij7 to ! rem>kable diff]5ces 9 texture & composition noticeable )9 "s l>ge bodies ( eruptive mat]ial1 & to ! evid5ce :i* ^! diff]5ces furni% ( a segregation or diff]5tiation among ! con/itu5ts ( an eruptive mass aft] x has be5 inject$ into its position )9 ! cru/ ( ! e>?4 ,table ( ! ,p]iods ( ,volcanic ,action 9 ! ,briti% ,isles & ( ! ,*ronological ,di/ribution ( ! ,volcanic ,products4 ,key to ,columns ,gr ,granites1 ,granophyres1 etc4 ,fe ,felsites1 ,rhyolites1 etc4 ,da ,dacite1 ,pit*/one ( ,eigg4 ,tr ,tra*ytes4 ,an ,&esites 7,porphyrites74 ,ga ,gabbros4 ,d ,dol]ites1 ,basalts 7,diabases74 ,pi ,picrites & highly basic lavas4 ,tu ,tuffs1 acid or basic4 ---------------------------------------- ------------------------- ,gr ,fe ,da ,tr ,an ,ga ,d ,pi ,tu ---------------------------------------- ------------------------- ,old] ,t]ti>y 7,plateaux1 dykes1 necks1 bosses1 sills7 99 99 99 99 99 99 99 99 99 ,mesozoic ,no volcanic rocks4 ,p]mian 99 99 99 99 99 ,c>bonif]\s 8 ,puy type 99 99 99 99 99 ,plateau type 99 99 99 99 99 99 ,devonian 99 99 ,old ,r$ ,s&/one ,upp] 99 99 ,l[] 99 99 99 99 99 99 ,silurian ,upp] 99 99 ,l[]1 ,bala 99 99 99 99 99 99 99 99 ,ar5ig 99 99 99 99 99 99 99 ,cambrian 99 99 99 99 ,uriconian 99 99 99 ,dalradian 99 8 ,torridonian ,lewisian 99 99 99 ---------------------------------------- ------------------------- ,f ! hi/ory ( volcanic action 9 ! ,briti% ,isles x is cle> t diff]5tiation is effect$ "u ?ree di/9ct conditions4 ,9 ! fir/ place1 a notable diff]5ce may be occasionally obs]v$ betwe5 two adjac5t p>ts ( ! same mass ( lava :i* has fl[$ out at ! surface4 ,?us1 9 ! ,c>bonif]\s picrite ( ,blackburn1 !re has be5 a sep>ation ( ! heavy basic con/itu5ts1 :i* h 9 great "p settl$ d[n into ! l[] "p ( ! %eet1 :ile ! light] felsp> has ma9ly come to ! top4 ,9 ?is case ! gradual transition f top to bottom sugge/s t ! sep>ation occurr$ aft] ! lava _h rea*$ ! surface & tak5 ! =m ( a /ream or %eet4 ,9 ! second place1 segregation has tak5 place 9 ! magma )9 ! t]re/rial cru/ aft] intrusion1 = x is frequ5tly obs]vable 9 l>ge bosses & sometimes 9 sills1 ! basic elem5ts hav+ t5d$ to mass !mselves t[>ds ! m>g9s ( ! rock1 leav+ m acid mat]ial 9 ! c5tre4 ,! cases ( ,g>abol ,hill among ! ,dalradian s*i/s ( ,scotl&1 ( ,c>rock ,fell among ! ,silurian /rata ( ! ,lake ,di/rict1 & ( ! ,cramond picrite among ! ,c>bonif]\s =mations ( ,midlo?ian1 ) o!rs t might be cit$ f v>i\s o!r regions & geological =mations 9 ,brita91 prove to :at a consid]able ext5t a sep>ation ( +r$i5ts may take place 9 a boss1 & ev5 sometimes 9 a comp>atively ?9 sill be=e ! molt5 mass consolidates4 ,9 ! ?ird place1 !re is good evid5ce t already be=e ! magma is ei!r intrud$ or extrud$1 & :ile x /ill lies )9 ! int]nal res]voir1 x may n possess a g5]al uni=mity ( composition1 b may h become m or less het]og5e\s4 ,9 reg>d to intrusive rocks1 ! extraord9>ily b&$ gabbros ( ! ,t]ti>y s]ies ( ,skye obvi\sly proce$$ f a magma 9 :i* ! molt5 mat]ial consi/$ 9 "s p>ts ma9ly ( felsp>1 & 9 o!rs ma9ly ( ! f]ro-magnesian m9]als & iron-ores4 ,/reams f ^! diff]5tly con/itut$ p>ts ( ! magma 7 simultane\sly or successively inject$ z sills into ! old] portions ( ! volcanic s]ies1 :ile1 z ! process ( diff]5tiation )9 ! magma proce$$1 /ill m felspa?ic liquid 0 left beh9d1 to be ?ru/ into cracks 9 ! sills previ\sly consolidat$4 ,moreov]1 ! b&$ basalts ( ! ,t]ti>y plateaux %[ t ?is het]og5eity 0 n conf9$ to int]nal intrusions1 b ma9ta9$ its place ev5 :5 ! molt5 mat]ial 0 eject$ to ! surface4 ,! diff]5tiation inde$ is n s /rik+ !re z among ! sills ( gabbro2 b its pres5ce1 ev5 9 a less degree1 proves t ! sep>ation ( con/itu5t m9]als 0 n due to any g5]al cool+ ( an erupt$ body ( igne\s rock1 b 0 already develop$ 9 ! res]voir f :i* ! molt5 mat]ial 0 propell$ to ! surface4 ,att5tion has be5 call$ to ! rem>kable simil>ity ( /ructure betwe5 ^! b&$ intrusive rocks & "s ( ! anci5t gneisses4 ,! resemblance is s close t we may ) e probability inf] t ! gneisses acquir$ _! *>act]i/ic b&+ z intrusive masses ( igne\s rocks1 dis*>g$ f het]og5e\s magmas1 l t :i* suppli$ ! gabbros ( ! ,cuill9 ,hills4 ,& z ^! gneisses belong to pre-,cambrian =mations1 we are ?us l$ to ! int]e/+ result t ! t5d5cy to develop het]og5eity 0 already z *>act]i/ic ( ! magma-bas9s ( ! e>lie/ geological "t z x has be5 ( ^? ( lat] p]iods4 ,! evid5ce ( diff]5tiation pres5t$ by sup]ficial lavas1 & by intrusive sills & bosses1 acquires great int]e/ :5 consid]$ 9 connection ) ! *anges :i* are se5 to h occurr$ 9 ! "* ( ! mat]ials erupt$ dur+ ! c\rse ( a def9ite volcanic p]iod4 ,an att5tive exam9ation ( ! volcanic products ( ! v>i\s ages1 s fully record$ 9 ! geological /ructure ( ! ,briti% ,isles1 %[s t a recognizable sequ5ce 9 ! nature ( ! mat]ials erupt$ dur+ a s+le volcanic p]iod c be trac$ f ! e>lie/ to ! late/ times1 & t1 9 spite ( occasional dep>tures1 ! normal ord] rema9s broadly uni=m4 ,) ! important exception ( ! ,sn[donian region & possibly o!rs1 we f9d t ! e>li] eruptions ( ea* p]iod 7 g5]ally mo/ basic1 & t ! lat] intrusions 7 mo/ acid4 ,?us ! diabase-lavas & tuffs at ! base ( ! ,cambrian s]ies ( ,/4 ,david's are pi]c$ by qu>tz-porphyry ve9s4 ,! &esites ( ! ,l[] ,old ,r$ ,s&/one 7 succe$$ by bosses1 sills1 & dykes ( granite1 felsite1 & lamprophyre4 ,! eruptions ( ! ,c>bonif]\s plateaux began ) extremely basic lavas1 & end$ ) tra*ytes1 felsites1 & qu>tz-porphyries4 ,! basalts ( ! great lava-fields ( ! ,t]ti>y p]iod are pi]c$ by masses ( granophyre & ev5 granite4 ,!re has evid5tly be51 on ! :ole1 a progressive dim9ution 9 ! quantity ( bases & a correspond+ increase 9 ! proportion ( acid 9 ! lavas erupt$ dur+ ! lapse ( "o volcanic p]iod4 ,?is sequ5ce is s well m>k$ & s common t x _c be m]ely accid5tal4 ,! acid & basic rocks1 occurr+ z !y d at ea* volcanic c5tre 9 ! same relation to ea* o!r1 are obvi\sly p>ts ( "o connect$ s]ies ( eruptions4 ,we seem to see 9 ?is sequ5ce an indication ( :at 0 tak+ place )9 ! subt]ranean magma4 ,!re 0 fir/ an ext5sive sep>ation ( ! m basic con/itu5ts1 su* z ! f]ro-magnesian m9]als & ores1 & ! lavas :i* came (f at t "t 7 heavy & basic basalts1 & ev5 picrites4 ,! removal ( ^! elem5ts left ! magma m acid1 & su* rocks z &esites 7 p\r$ out1 until at la/ ! deep] intrusive sills1 dykes & bosses became ?or\ghly acid rocks1 su* z felsite1 qu>tz-porphyry & granite1 :ile if any sup]ficial outfl[ took place x 0 su* a rock z dacite4 ,9 ! case ( ! ,t]ti>y volcanic s]ies !re is evid5ce t aft] ! acid protrusions a f9al uprise ( basic mat]ial occurr$4 ,no satisfactory pro( ( any simil> return to basic eruptions has be5 detect$ among ! ,palozoic =mations4 ,b x is possible t "s ( ! basic sills & dykes1 ! precise age ( :i* _c be fix$1 may really m>k su* a rev]sion1 ev5 9 ! e>li] volcanic p]iods4 ,"s illu/rative examples ( volcanic cycles f o!r c\ntries 7 cit$ 9 ,*apt] iii4 ,to ^! ,i may add ano!r in/ance :i* pres5ts a close analogy to "s ( ! ph5om5a *>act]i/ic ( ! ,briti% examples ( ,palozoic z well z ( ,t]ti>y age4 ,monte ,v5da 9 ! ,euganean ,hills1 already allud$ to 7p4 #dgd71 may be cit$ z an int]e/+ specim5 ( an old] ,t]ti>y volcano1 :i* has be5 s dissect$ by d5udation z to %[ n only ! succession ( its sup]ficial dis*>ges1 b ! position & ord] ( its subt]ranean intrusions4 ,! volcanic eruptions ( ?is neighb\rhood1 judg+ f ! area :i* !y /ill cov] & ! height !y rea*1 may h pil$ up a m\nta9 rivall+ or surpass+ ,etna 9 dim5sions4 ,9 ,monte ,v5da ! l[e/ visible igne\s rocks are sills ( oligoclase-tra*yte t h be5 ?ru/ betwe5 & h highly alt]$ ,cretace\s 7,ti?onian7 lime/ones4 ,o!r intrusive %eets ( tra*yte foll[ 9 ! ov]ly+ ,cretace\s /rata 7,neocomian & ,scaglia74 ,x is n until ! old] ,t]ti>y =mations are rea*$ t und\bt$ tuffs & lavas occur1 indicative ( truly int]/ratifi$ volcanic mat]ials4 ,^! =mations1 consi/+ ( nummulitic lime/ones & o!r /rata toge!r ) fossilif]\s tuffs1 %[ t ! volcano began z a subm>9e v5t4 ,x dis*>g$ d>k basic dol]ites & tuffs4 ,! highe/ lava1 h[ev]1 cr[n+ ! summit ( ! m\nta9 is a tra*yte4 ,!re appe>s to h be5 a rapid decrease ( ! bases 9 ! magma1 = ! lat] lavas 7 rhyolites1 accompani$ ) rhyolitic tuffs ( ,oligoc5e age1 & foll[$ 9 ! end by ! black vitre\s tra*yte ( ,monte ,sieva4 #ab4 ,f ! evid5ce detail$ 9 ^! volumes1 x appe>s t ! sequ5ce f basic to acid dis*>ges 0 on ! :ole *>act]i/ic ( ea* eruptive p]iod4 ,x is obvi\s1 h[ev]1 t z ! protrusions ( successive p]iods took place )9 ! same limit$ geographical area1 ! int]nal magma dur+ ! int]val betwe5 two su* p]iods mu/ 9 "s way h be5 r5ew$ z reg>ds its con/itution1 = :51 aft] long quiesc5ce1 eruptions began once m1 basic lavas appe>$ fir/ & 7 ev5tually foll[$ by acid k9ds4 ,?is cycle ( trans=mation is admirably exhibit$ 9 ,c5tral ,scotl&1 :]e ! &esites ( ! ,old ,r$ ,s&/one ) _! felsite sills are foll[$ by ! limburgites1 picrites & o!r highly basic lavas at ! bottom ( ! ,c>bonif]\s plateaux1 succe$$ 9 turn by ! &esites1 tra*ytes & acid sills ( t s]ies4 ,:5 ! puy eruptions ensu$1 ! magma _h once m become decid$ly basic4 ,t ! true explanation ( ^! alt]ations is ( a complex ord] may be inf]r$ f ! exceptions :i* occur to ! g5]al rule4 ,i h allud$ to ! ,sn[don region1 :]e ! acid rhyolites are foll[$ by m basic &esites1 & :]e ! sills are also m basic ?an ! sup]ficial lavas4 ,9 ! ,ar5ig & ,cad] ,idris c\ntry ! sills are likewise m basic ?an ! b$d$ lavas4 ,among ! ,c>bonif]\s puys ( ! bas9 ( ! ,fir? ( ,=?1 ! sills are n s5sibly m acid ?an _m ( ! sup]ficial basalts1 & !y ev5 include su* rocks z picrite4 ,possibly 9 ?is la/-nam$ region we see an arre/$ sequ5ce1 ! volcanic protrusions hav+ f "s cause ceas$ be=e ! g5]al uprise ( ! m acid magma4 ,,index ,aa =m ( lava 9 ! ,s&wi* ,isl&s1 ii4 #ahg ,ab]eiddy ,bay1 i4 #bjf ,abi*1 ,h41 i4 #cb ,acid igne\s rocks1 silica p]c5tage (1 i4 #ad2 devitrification (1 #ai2 fl[-/ructure (1 #ba2 occur 9 ?ick] %eets ?an basic1 #bd2 alt]nations (1 ) basic1 #bh1 #fa1 #aeb1 #aeg1 #afe1 #bjg1 #bac1 #bcc1 #bhd1 #cah2 ii4 #bcf1 #bff1 #bgh2 metamorphic action (1 i4 #ie1 #if2 connection ) m\nta9s1 ii4 #ih2 sc5]y (1 #ajb4 ,acids1 m9]al1 at volcanoes1 i4 #gb ,acl&1 ,mr4 ,h4 ,d41 i4 #acc ,aegean ,sea1 volcanoes (1 i4 #a ,agglom]ates1 i4 #ca1 #eg1 #eh2 9 dykes1 #gj2 ,ar*an1 #abj1 #acj1 #ace2 ,cambrian1 #adh1 #adi1 #afg2 ,silurian1 #agh1 #ahj1 #aha1 #ahd1 #ahe1 #aid1 #aii1 #bjf1 #bad1 #bcg1 #bda1 #bdd1 #bdg1 #bec1 #bee2 ,old ,r$ ,s&/one1 #bgi1 #bhe1 #bhi1 #cjj1 #cac1 #cbe1 #cch1 #cdi1 #ceb2 ,c>bonif]\s1 #cha1 #cii1 #djb1 #djd1 #dbg1 #dbi1 #dci1 #ddj2 ii4 #ac1 #bd1 #bh1 #bi2 ,p]mian1 #fb1 #fd1 #ii2 ,t]ti>y1 #aid1 #bgg1 #bgh1 #bha1 #bhi1 #bib1 #bic1 #chd1 #djj1 #dbc ,allan1 ,t41 i4 #cfc ,allotriomorphic m9]als1 i4 #ba ,allport1 ,mr41 i4 #ie1 #acj1 #aca1 #bfj1 #dea2 ii4 #aa1 #db1 #ajb1 #ajc1 #ajd1 #ajf1 #cgj ,amb] 9 ,t]ti>y volcanic s]ies1 ii4 #aih ,am]ica1 ,we/]n ,nor?1 volcanic rocks (1 i4 #aj1 #ajj2 ii1 #bfg ,amygdales1 orig9 (1 i4 #ae2 ii4 #ahi1 #bba1 #bhe1 #bij ,amygdaloidal /ructure1 i4 #ae1 #af1 #ag1 #ei1 #bgd1 #che2 ii4 #c1 #ca1 #eg1 #abi1 #ahh ,analyses ( ,cambrian tuffs1 i4 #adh1 #adi2 ( ,cambrian diabases1 #aec2 ( ,old ,r$ ,s&/one diabases1 #bgd2 ( ,old ,r$ ,s&/one &esites1 #bge2 ( ,old ,r$ ,s&/one tra*ytes1 #bgf2 ( ,old ,r$ ,s&/one felsites1 #bgh2 ( ,c>bonif]\s limburgite1 #cgg2 ( ,c>bonif]\s basalts1 #cgi2 ( ,c>bonif]\s tra*ytes1 #chj2 ( ,c>bonif]\s phonolite1 #cha2 ( ,t]ti>y tra*yte1 ii4 #aci2 ( ,t]ti>y dacite1 #bdd ,&]son1 ,dr4 ,tempe/1 ii #bfa1 #bfb1 #bfc ,&esite1 i4 #bd1 #aca1 #acf1 #afd1 #afe1 #afg1 #agh1 #ahj1 #ahd1 #ahi1 #aij1 #bjd1 #bab1 #bac1 #bad1 #bae1 #bbi1 #bcj1 #bde1 #bdf1 #bdg1 #beb1 #bgd1 #bge1 7analyses71 #bgg1 #bib1 #cjj1 #cjf1 #cji1 #cae1 #cah1 #cbe1 #ccj1 #ccc1 #cde1 #cgg1 #cgi1 #chf1 #djc1 #dba2 ii4 #de1 #eg1 #if1 #abe1 #acg1 #ahd1 #bcf1 #dbd ,anglesey1 gneisses & s*i/s (1 i4 #abf2 volcanic rocks (1 #ahi1 #bai ,anhydrite deposits1 ii4 #ed ,ann&ale1 ,p]mian volcanic rocks (1 ii4 #ef1 #eh1 #fj1 #fa1 #ff ,antrim1 ,old ,r$ ,s&/one volcanic rocks (1 i4 #cad2 ,t]ti>y volcanic rocks (1 #dg1 #eb2 ii4 #aji1 #aaj1 #aac1 #aci1 #adj1 #aii2 basalts (1 #aib1 #aic1 #aii1 #bjb1 #bjf2 clays & iron-ore (1 #bjd2 rhyolites (1 #ahe1 #cfd1 #cgj1 #cga1 #dbf1 #dde2 deceptive agglom]ate (1 #ahh2 rhyolitic conglom]ate (1 #aie1 #bjf2 plateau (1 #aii2 tuffs (1 #bjb1 #bjd2 v5ts (1 #bga1 #bgg2 sills (1 #bih2 c5tral subsid5ce ( basalt-plateau (1 #ddh ,apatite1 ii4 #ace ,apjohn1 ,j41 ii4 #db ,applecross1 volcanic v5ts 91 ii4 #bib ,arans1 !1 i4 #age1 #agf1 #agi1 #ahd1 #ahf1 #bjg ,ar*an p]iod1 i4 #aaj1 #aaa2 volcanic rocks (1 #abj ,ardnamur*an1 dykes & ve9s (1 ii4 #aed1 #cbj2 basalt-plateau (1 #bjh2 v5ts (1 #bhg2 sills (1 #cah2 gabbro (1 #cee ,ar5ig gr\p1 i4 #age2 l[] limit (1 #agg1 #ahe2 top (1 #agh1 #bbh1 #bdf ---- volcano (1 i4 #db1 #age1 #agf1 #agi1 #ahf1 #bjg ---- rocks 9 ,scotti% ,highl&s1 i4 #abc1 #abf2 9 ,m]ione?%ire1 #agf1 #agi2 ( ,%rop%ire1 #ahi2 ( ,ayr%ire1 #aif2 ( ,scotti% ,highl&s1 #bja2 ( ,anglesey1 #bba2 ( ,lake di/rict1 #bbi2 ( ,irel&1 #bci ,argyll1 ,duke (1 ii4 #aac1 #aad1 #aih ,argyll%ire1 dykes (1 ii4 #abg1 #abh1 #ach1 #adb1 #adf1 #aga1 #agb2 v5ts (1 #bgh ,arizona1 explosion crat] 91 i4 #eh2 laccolites 91 #hf ,arran1 ,old ,r$ ,s&/one volcanic rocks (1 i4 #bih1 #caa2 ,c>bonif]\s volcanic rocks (1 #chf1 #cib2 possible ,p]mian volcanic rocks (1 ii4 #eh2 granite (1 i4 #ic2 ii4 #cff1 #cfg1 #dah2 pit*/one (1 i4 #ai2 ii4 #dde2 dykes (1 #abc1 #aci1 #adj1 #adb1 #adf1 #aed1 #afa ,ar?ur ,seat1 i4 #cfd1 #cgc1 #cgh1 #che1 #chf2 ii4 #fg ,arvonian1 i4 #ade1 #aef ,asbe/os 9 volcanic breccia1 ii4 #ea ,asc5sion ,isl&1 cellul> lava (1 i4 #ae ,a%es1 volcanic 7see ,tuffs7 ,a%pr+ton volcanic s]ies1 i4 #bfb ,asphalt1 ii4 #gi ,a!r/one1 i4 #agj ,augite1 loose cry/als (1 9 volcanic v5ts1 i4 #fb1 #agh1 #aha2 ii4 #eh1 #gi2 lumps (1 9 volcanic v5ts1 i4 #ceb ,augite-aphanites1 i4 #agh ,auv]gne1 old volcanoes (1 i4 #bi1 #cb1 #ff1 #gj1 #ajj2 ii4 #cgc ,avel9e1 ,mr4 ,w4 ,t41 i4 #bbg1 #bcj2 ii4 #cb ,ayr%ire1 example ( volcanic neck 91 i4 #ef2 ,silurian volcanic rocks (1 #aib2 ,old ,r$ ,s&/one volcanic rocks (1 #bge1 #bhb1 #bhc1 #bhe1 #bia1 #cca2 ,c>bonif]\s volcanic plateau (1 #ajb1 #cfh1 #chh1 #cic1 #cih1 #daj2 ,c>bonif]\s ,puys (1 #dae1 #daf1 #dcd1 #ddj1 #dgd2 ,p]mian volcanic rocks (1 ii4 #ee1 #eh1 #fb ,azoic p]iod1 i4 #aji ,bck/rm1 ,mr41 ii4 #bff ,baily1 ,w4 ,h41 i4 #bea1 #beb2 ii4 #aih1 #ddi ,bala gr\p1 i4 #age1 #aij1 #aif1 #bja1 #bjf1 #bjg1 #bbc1 #bdb2 lime/one (1 #dg1 #age1 #bbi1 #bde1 #bea2 volcanic rocks (1 #ahf1 #aij1 #bjg1 #bac1 #bba1 #bda1 #bdh ,balbriggan1 igne\s rocks (1 i4 #bdd ,ballagan b$s 7,l[] ,c>bonif]\s71 i4 #chd1 #chg1 #cib1 #cic1 #dab1 #ddg ,ballantrae1 volcanic rocks at1 i4 #aib1 #aii ,ballypallidy1 tuffs & leaf-b$s (1 ii4 #bjd1 #dbi ,bambor\gh1 ,:9 ,sill at1 ii4 #b1 #c1 #e ,b&+ ( igne\s rocks1 i4 #hd1 #bjg2 ii4 #ahi1 #bid1 #cbi1 #ced1 #ceg1 #dgf ---- ( gneiss1 i4 #aaf ,bangor gr\p1 i4 #aff ,banks1 ,sir ,joseph1 ii4 #aji ,b>navave1 eruptive rocks (1 ii4 #dba ,b>r[1 ,mr4 ,g41 i4 #bja1 #bbf1 #bgb1 #bgi1 #chj2 ii4 #adg1 #adh ,basalt1 column> /ructure (1 i4 #bd1 #be2 relation to gabbro1 #gh2 alt]$ by c>bonace\s /rata1 #ie2 %ells suppos$ to occur 91 ii4 #aaj2 b&$1 #ahi2 ?ickness ( %eets (1 #aib2 mean+ ( r$ lay] betwe5 %eets (1 #aig1 #bjc1 #bjf1 #bed2 metamorphism (1 #bgb1 #bgf1 #ccg1 #cci1 #cdj1 #cdg1 #cee1 #cef1 #ceg1 #ceh1 #cfb1 #cgh1 #chc1 #chf1 #cig1 #cii1 #djj1 #djd1 #dac ---- pre-,cambrian1 i4 #aai1 #aca2 ,silurian1 #bjf1 #bjg1 #bcj1 #bde2 ,c>bonif]\s1 #cgh1 #djc1 #djg1 #dag2 ii4 #aa1 #de1 #df2 ,p]mian1 #eg1 #if2 ,t]ti>y1 #abe1 #acf1 #ahc1 #aii1 #bjh1 #bia ,basalt-conglom]ate1 ii4 #aie ,basic volcanic rocks1 silica-p]c5tage (1 i4 #ad2 devitrification (1 #bj2 fl[-/ructure (1 #ba2 occur 9 ?9n] %eets ?an ! acid1 #bd2 metamorphic action (1 #id2 erupt$ at l[ levels1 #ih2 sc5]y (1 #ajb2 conv]t$ into s*i/s by de=mation1 #ge1 #aad1 #aah1 #aai1 #abd1 #abi2 alt]nation ) acid1 #bh1 #fa1 #aca1 #aeg1 #afe1 #bjg1 #bac1 #bcc1 #bhd1 #cah2 ii4 #bcf1 #bff1 #bgh ,bass ,rock1 i4 #cgb1 #cgc1 #djc ,bass5?waite ,lake1 i4 #cce ,ba?gate1 puy eruptions (1 i4 #ddj1 #ddb1 #dde1 #def1 #dfa ,bau]1 ,dr4 ,m41 i4 #fb ,bauxite1 ii4 #aig1 #bjd ,bayley1 ,mr4 ,w4 ,s41 ii4 #ccj ,b$d+ 9 lavas1 i4 #bd ,bell1 ,sir ,i4 ,l[?ian1 ii4 #a1 #aac1 #acg1 #afe ,bemrose1 ,mr4 ,h4 ,a41 ii4 #aj1 #aa1 #ac1 #af1 #ag1 #ah1 #bj1 #ba ,b5 ,crua*an1 alt]ation ( granite at1 i4 #cdc ---- ,hiant1 basic sills (1 ii4 #cah ,b5aun ,m1 felsite (1 i4 #cdg ,b]g]1 ,j4 ,f41 ii4 #bb1 #ie1 #aaj1 #aac1 #aci1 #adj1 #ada1 #ade1 #aii1 #cfd1 #dbf ,b]tr&1 ,pr(4 ,m41 i4 #bh ,b]wick%ire1 i4 #bgb1 #bij1 #cch1 #cge1 #che1 #dja1 #dac ,b]wyn ,hills1 i4 #agf1 #ahf1 #bjh1 #bah ,bigg>1 volcanic area1 i4 #bhg1 #cbe ,b9ney1 ,e41 ii4 #ef ,b9ny ,craig type ( basalt1 i4 #dai1 #dba 7#ddd7 ,biotite 7see ,mica7 ,bitum5 9 intrusive rocks1 i4 #dba ,black/one 7,d]by%ire71 ii4 #ah1 #ba ,blair-,a?oll ,lime/one1 i4 #abb ,blake1 ,rev4 ,j4 ,f41 i4 #abf1 #acj1 #add1 #afj1 #afa1 #afb1 #afc1 #afe1 #aff1 #afh1 #bbj1 #bba1 #bbb ,blocks1 eject$1 i4 #cf1 #dbc1 #dch2 ii4 #aig1 #bba ,bole betwe5 lavas1 i4 #ddb2 ii4 #aig1 #bjc1 #bjf1 #bed ,bombay1 volcanic plateau (1 ii4 #ahj ,bombs1 volcanic1 i4 #fj2 ii4 #ci ,bonney1 ,pr(41 i4 #ie1 #abf1 #acj1 #acf1 #add1 #afj1 #afb1 #afc1 #afd1 #afe1 #aff1 #afg1 #afh1 #aib1 #baj1 #bbg ,borr[dale ,volcanic ,s]ies1 i4 #bbg ,bosses1 volcanic1 i4 #ef1 #gh1 #hh2 petrography (1 #hi2 diff]5tiation 91 #ij2 ii4 #dgf2 granitic1 i4 #ic2 metamorphism ar\nd1 #id1 #ie2 conditions ( _! intrusion1 #ig1 #ih2 wea!r+ (1 #ajb ---- ,silurian1 i4 #bae1 #bce2 ,old ,r$ ,s&/one1 #bgg1 #bhh2 ,c>bonif]\s1 #djc1 #deh ---- ,t]ti>y1 ii4 #bga1 #bhd1 #cbg1 #cff1 #cgh1 #cie1 #djc2 b\nd>ies (1 #chb2 relation to old] eruptive v5ts1 #bhj1 #chd1 #cii2 relation to plateau basalts1 #chf1 #cif1 #djb1 #djd2 relation to gabbro intrusions1 #cia1 #djb1 #djd2 relation to ! basic dykes1 #cie ,bo/onite1 ii4 #dg ,b\1 ,ami1 i4 #bfh1 #cfc2 ii4 #aab1 #cgb ,b\le1 ,m41 i4 #bg1 #bi1 #dd1 #de1 #df1 #fa2 ii4 #cge ,b\tan1 ,m41 i4 #fb ,b[d5 ,hill1 type ( dol]itic basalt1 i4 #dah1 #dba ,braid ,hills1 great v5t (1 i4 #bhi1 #bic1 #caa1 #cah1 #cbc ,branco1 ,pr(4 ,w41 i4 #df1 #dag ,breccias1 volcanic1 i4 #ca1 #cb1 #abj1 #aca1 #ace1 #adg1 #afe1 #ahi1 #aij1 #aig1 #bac1 #bbd1 #bbe1 #bcc1 #bcd1 #bdf1 #beb1 #bee1 #bhi1 #cdg2 ii4 #ci1 #da1 #di1 #aie ---- ( non-volcanic mat]ials1 ii4 #aif1 #dbc ,brecciat$ /ructure1 i4 #afb1 #baa ,breidd5 ,hills1 i4 #agf1 #aij1 #bjh ,br5t ,tor1 ii4 #cc1 #ce1 #cf ,bron1 ,m4 ,r41 ii4 #aia ,brita91 advantage\s position (1 = ! /udy ( anci5t volcanic action1 i4 #f2 complet5ess ( ! ,geological ,record 91 #f2 direction ( folds & fractures 91 #aa2 *ief lavas f\nd 91 #ca2 ,vesuvian cones (1 #db2 volcanic plateaux (1 #dc2 puys (1 #df2 lacu/r9e volcanoes (1 #di2 fissure eruptions (1 #eb2 sc5]y ( volcanic rocks (1 #ajj1 #aja2 pre-,cambrian rocks (1 #aaa2 9 ,cambrian "t1 #ada2 9 ,silurian "t1 #agc2 9 ,devonian "t1 #beh2 9 ,old ,r$ ,s&/one "t1 #bfc2 9 ,c>bonif]\s "t1 #cee2 9 ,p]mian "t1 ii4 #ec2 9 old] ,t]ti>y "t1 #ajh ,brgg]1 ,pr(41 i4 #bh1 #hh1 #ij1 #ia1 #ib ,bryce1 ,j41 i4 #cad1 #cfi ,bu*1 ,l4 von1 i4 #bg2 ii4 #cha ,buckl&1 ,w41 ii4 #ie1 #aaj1 #aac ,buddle1 ,j41 ii4 #aac ,buil?1 i4 #agf1 #bjc ,burdieh\se ,lime/one1 i4 #cfa1 #cgd1 #chh1 #dae1 #dfc ,burnt ,c\ntry ( ,asia ,m9or1 i4 #b ,burntisl&1 ,b9n (1 i4 #dbh1 #dbi1 #dcc1 #dce1 #deg1 #dei ,burntisl& ,sill type ( dol]ite1 i4 #dah1 #dba ,busz1 ,mr4 ,k41 i4 #bfa ,bute1 ,isle (1 i4 #cfi1 #cgh1 #djg ,cadell1 ,mr4 ,h4 ,m41 i4 #aad1 #dbc2 ii4 #ccd ,cad] ,idris1 volcanic rocks (1 i4 #db1 #age1 #agf1 #agg1 #agh1 #agi1 #ahj1 #aha1 #ahb1 #ahh1 #bjg ,ca] ,c>adoc1 i4 #aca1 #acb1 #agj ,ca]fai gr\p 7,cambrian71 i4 #aee ,ca]n>von%ire1 volcanic rocks (1 i4 #aei1 #bjg ,cai?ness ,flags1 i4 #cdc1 #ceb ---- volcanic v5ts 91 i4 #ceb ,calcif]\s ,s&/ones1 i4 #cfa1 #cff1 #dae ,calcite z a matrix ( tuffs1 ii4 #bg1 #ci1 #da ,caldecote volcanic rocks1 i4 #agj ,callaway1 ,dr4 ,c41 i4 #abf1 #acj1 #acb1 #acd1 #bbj1 #bba ,calton ,hill1 lavas & tuffs (1 i4 #cgc1 #cgh1 #che1 #chf1 #chi ,cambrian sy/em1 i4 #aab1 #abc1 #acc1 #aci1 #adc1 #add2 volcanoes (1 #ade1 #aei ,campbelt[n1 volcanic rocks (1 i4 #cab1 #chf ,campsie ,fells1 i4 #ajb1 #cfh1 #cfi1 #chd1 #chf1 #chi1 #cic1 #cig1 #cih1 #djj1 #djc1 #daj1 #dab1 #ddg ,can>y ,isl&s1 i4 #bg ,canna1 basalts (1 ii4 #ahd1 #ahg1 #aij1 #bae1 #baf2 v5t 91 #bhh ,cantyre1 volcanic rocks (1 i4 #caa1 #cfi1 #cgj1 #chf ,c>adoc gr\p1 i4 #age1 #aif ,c>bonace\s rocks1 influ5ce (1 on igne\s masses1 i4 #ie1 #dbf1 #ddi1 #def2 ii4 #fe1 #hg1 #ajd1 #afe ,c>bonif]\s ,lime/one1 orig9 (1 i4 #ceg ---- sy/em1 subdivisions (1 9 ,brita91 i4 #ceh1 #cfj1 #cff2 anci5t geography (1 #cee1 #cfa1 #cfb1 #dcb1 #dfb2 flora & fauna (1 #cef ---- volcanic plateaux1 di/ribution (1 i4 #cfd1 #cfg2 nature ( mat]ials con/itut+1 #cgg2 /ructure (1 #chc2 b$d$ lavas & tuffs (1 #chc2 v5ts (1 #ed1 #cid1 #cii ---- ,puys1 i4 #df1 #dg1 #cjh1 #cfd2 ( ,scotl&1 #dad2 nature ( ! mat]ials erupt$ by1 #daf2 necks (1 #dbd2 b$d$ lavas & tuffs (1 #dag1 #dcf1 #ddj2 sills (1 #ddf1 #dgb2 bosses (1 #deh1 #dfe2 dykes (1 #dfj2 ( ,d]by%ire1 ii4 #h2 ,isle ( ,man1 #bb2 ( ,som]set1 #cb2 ( ,devon%ire1 #cb2 ( ,k+'s ,c\nty1 #cg2 ( ,lim]ick1 #da ,c>l+=d1 igne\s rocks (1 i4 #if2 ii4 #age1 #cga1 #dbj ,c>n$d ,dafydd1 i4 #bji ,c>nmony ,hill1 ii4 #bgb ,c>rock ,fell1 diff]5tiation 9 rocks (1 i4 #ia2 metamorphism at1 #id1 #if2 z a volcanic boss1 #bce1 #bcf ,cem5t-/one gr\p1 i4 #cfb1 #cff1 #chg1 #dah1 #dfb ,cellul> /ructure ( volcanic rocks1 i4 #ae1 #cc ,*alk1 metamorphism (1 by a dyke1 ii4 #afd ,*amp]n[ne1 ,a41 i4 #bfj1 #bfb ,*>nwood ,=e/1 i4 #acd2 ii4 #ec ,*]ts associat$ ) volcanic rocks1 i4 #abc1 #afg1 #afi1 #agc1 #agd1 #ahd1 #aif1 #aig1 #bdj1 #bed2 ii4 #be1 #cf ,*eviot ,hills1 i4 #ajb1 #bga1 #bgb1 #bgd1 #bge1 #bgg1 #bgh1 #bij1 #bic1 #ccf ,*ill$ m>g9 9 intrusive rocks1 i4 #ha1 #hc2 ii4 #abf1 #aeh1 #afj1 #agb1 #bii1 #cjc1 #caj1 #cag1 #cba1 #cib1 #djb ,*ri/iania1 eruptive rocks (1 i4 #bh ,*ronology1 volcanic1 h[ det]m9$1 i4 #df ,cl>k1 ,mr4 ,g4 ,t41 ii4 #ahj ,clay/one1 i4 #bgg1 #bgi1 #cah1 #cbd1 #cbg2 ii4 #djc ,cleavage1 effects (1 on igne\s rocks1 i4 #afb1 #afe1 #bbd1 #bca1 #bcb1 #bcd1 #bcg1 #bfj1 #bfa2 ii4 #cf ,clee ,hills1 ii4 #aja1 #ajb ,clevel& ,dyke1 ii4 #a1 #abb1 #aci1 #adj1 #adb1 #add1 #adf1 #adg1 #aej1 #aec1 #afg1 #afh1 #afi ,cl\gh1 ,mr4 ,c4 ,t41 i4 #aad1 #bja1 #bcf1 #bgd1 #bij1 #ccg2 ii4 #abc1 #abd1 #abg1 #abh1 #acb1 #acg1 #ach1 #adb1 #ade1 #adf1 #aeb1 #afb1 #aga1 #agb1 #caf1 #chd1 #dcg ,clyde1 ,c>bonif]\s volcanic plateau (1 i4 #cfh1 #chd1 #che1 #cic1 #djj1 #djg1 #daa ,coal int]b$d$ among volcanic rocks1 i4 #cib1 #dbc2 ii4 #aih1 #bac1 #bea1 #bhg ---- alt]ation (1 at volcanic v5ts1 i4 #gb2 ii4 #fd ---- alt]ation ( intrusive rocks by1 i4 #ie1 #dea ---- alt]ation ( by sills1 dykes1 etc41 ii4 #fg1 #afd1 #aff ,coal-measures1 i4 #ceh1 #cfj1 #cff ,coalbrookdale ,coal-field1 ii4 #ajc ,cole1 ,pr(4 ,g4 ,a41 i4 #agf1 #agg1 #agh1 #agi1 #ahj1 #aha1 #ahd1 #ahg1 #ahh1 #baj1 #baa2 ii4 #acd1 #bje1 #bab1 #bde1 #cgj1 #cga1 #cgh1 #dbf ,colorado1 ,gr& ,caon (1 i4 #cj2 laccolites (1 #hf ,column> /ructure1 i4 #be1 #bg1 #cdc1 #cgh1 #che1 #dei2 ii4 #afd1 #ahf1 #bjf1 #cja ,comley ,s&/one1 i4 #add ,cones1 volcanic1 connection (1 ) necks1 i4 #gj2 contemporane\s d5udation (1 #gc2 ii4 #bjb1 #bah1 #bcj2 entombm5t (1 i4 #dcc1 #dfc2 ii4 #ff ,conglom]ates1 volcanic1 i4 #ca1 #cg1 #ahc1 #aij1 #bhf1 #cjj1 #cjg1 #cji1 #caj1 #cad1 #cae1 #ccj1 #cda2 ii4 #aie1 #aih1 #bah1 #bhd ,coni/on ,lime/one1 i4 #bbi1 #bca ,contemporaneity 9 ,geology1 #bja ,cont95ts1 orig9 (1 i4 #aa ,contraction1 effects ( t]re/rial1 i4 #ab1 #ig1 #ih ,conybe>e1 ,j4 ,j41 ii4 #ie ---- ,w41 i4 #aga2 ii4 #i1 #ie1 #aaj1 #aac1 #aii ,cool+1 effects (1 9 induc+ v>ieties ( texture 9 igne\s rocks1 i4 #gh1 #gi1 #ha2 ii4 #bgd1 #bge1 #bii1 #cjc1 #caj1 #cag1 #cib1 #djb ,coon ,butte1 ,arizona1 i4 #eh ,cork1 ,c\nty1 volcanic breccias (1 ii4 #di ,corndon1 sill (1 i4 #agf1 #ahi1 #aij ,cor/on ,hill1 i4 #cgc1 #chf1 #chg ,craiglockh>t type ( dol]ite & basalt1 i4 #dah ,crat]1 consolidation ( tuff )9 a1 i4 #dbi ,crat]-lakes1 i4 #eh2 ii4 #bff1 #bge ,cretace\s p]iod1 geography ( !1 ii4 #ajh1 #ahb ,cross ,fell1 i4 #bbh1 #bbi1 #bch ,cross1 ,mr4 ,:itman1 i4 #hf ,cru%-conglom]ates or breccias1 i4 #cb1 #bbj1 #bbc1 #bbe1 #bdd2 ii4 #bha1 #cdg1 #ceb ,cru%+1 me*anical effects (1 i4 #cae 7see ,s*i/7 ,cru/1 contraction ( ! t]re/rial1 i4 #ab1 #ig1 #ih2 olde/ rocks (1 #aaj2 de=mation (1 #aag1 #aba1 #bfd1 #bie1 #big ,cryptocry/all9e type ( basalt1 i4 #dai ,cry/allites ( volcanic rocks1 i4 #ah ,cry/als1 diff]5t p]iods ( =mation (1 9 volcanic rocks1 i4 #ai1 #bj1 #ba1 #dba2 ii4 #abh1 #aca1 #acd1 #ace2 eject$ by volcanic v5ts1 i4 #fb1 #agh1 #ahj1 #aha1 #aie1 #bac1 #bcd1 #bde2 ii4 #bg1 #di1 #eh1 #gi ,cuill9 ,hills1 sc5]y (1 i4 #ajf2 gabbro (1 ii4 #cbi1 #cfa2 acid rocks (1 #cia ,culots1 i4 #gh1 #hh ,culm-measures1 ii4 #cc ,cumbrae ,isl&s1 i4 #cfh1 #cfi1 #cgh1 #djg ,cumm+1 ,j4 ,g41 ii4 #bb ,cycles1 volcanic1 i4 #bg1 #ib2 ii4 #aaf ,dacite1 i4 #bcj2 ii4 #ahe ,dakyns1 ,mr4 ,j4 ,r41 i4 #ij1 #bbi1 #bgb2 ii4 #aj ,dalmell+ton1 volcanic rocks at1 i4 #ccc2 ii4 #fb ,dalm5y type ( dol]ite & basalt1 i4 #dah1 #dbj ,dalradian rocks1 probable cru%$ necks (1 i4 #ge1 #abe2 lavas & sills (1 #aba2 gre5 s*i/s (1 #abd ,dalry1 ,ayr%ire1 buri$ volcanoes (1 i4 #dcd ,dana1 ,j4 ,d41 ii4 #ahi ,d>w91 ,c41 i4 #bg ,daubre1 ,a41 i4 #gb1 #djd ,davies1 ,j41 i4 #aef1 #aeg ,de*51 ,h4 von1 i4 #df2 ii4 #aab1 #bhj1 #ccc1 #cdj1 #cfg1 #cgb1 #cha ,de=mation1 effects (1 on volcanic rocks1 i4 #ge1 #aae1 #aag1 #aai1 #aba1 #abg1 #abi1 #afb ,de la ,be*e1 ,h41 i4 #adb1 #adc1 #agj1 #age1 #bjd1 #bje1 #bjg1 #bei2 ii4 #i1 #aj1 #ai1 #cc1 #ie1 #if1 #ig ,delessite1 ii4 #gi ,d5udation1 influ5ce (1 on volcanoes1 i4 #c1 #d1 #h1 #dj1 #dc1 #de1 #df1 #ed1 #eh1 #ga1 #gc1 #ge1 #gi1 #hg1 #ajj-ajg1 #cgj1 #dcc1 #dcd1 #dcf1 #dgf2 ii4 #ee1 #fa1 #fb1 #agi1 #aha1 #ahb1 #bda1 #bde1 #bdh1 #bdi1 #bee1 #beg1 #bhb1 #bhc1 #bib1 #caf1 #cag1 #cfc1 #cgc1 #djg1 #dee ,d]by%ire1 toad/ones (1 i4 #cei2 ii4 #h ,desm>e/1 ii4 #cgc ,devitrification ( volcanic rocks1 i4 #ah1 #ai1 #gh2 ii4 #dcg1 #ddf ,devonian sy/em1 i4 #beg2 volcanoes (1 #bei ,devon%ire1 volcanic sc5]y (1 i4 #ajc2 ,devonian volcanic rocks (1 #bei2 ,c>bonif]\s volcanic rocks (1 ii4 #cb2 ,p]mian volcanic rocks (1 #id ,diabase1 i4 #aea1 #aec 7analyses71 #aef1 #aib1 #aid1 #bjd1 #bjf1 #bad1 #bag1 #bce1 #bdj1 #bdg1 #bdi1 #bgc 7analyses71 #bgh1 #bib1 #cah1 #cbj1 #ccj1 #cce1 #cdd1 #cde1 #cea1 #djc2 ii4 #e1 #acf1 #dae ,diabase-porphyrite1 i4 #aib1 #bjd ,diamond f\nd 9 volcanic v5ts1 i4 #fb ,dick1 ,mr4 ,a41 jun41 i4 #chj ,dickson1 ,mr4 ,e41 ii4 #bc ,diff]5tiation 9 igne\s rocks1 i4 #bb1 #bg1 #hd1 #he1 #ij1 #ia1 #ddi2 ii4 #cjj1 #dge ,dimetian1 i4 #ade ,d+le-b$s1 i4 #cdf ,d+le1 ,upp] ,silurian nodul> lavas (1 i4 #bj1 #bed ,diorite1 i4 #gh1 #bdg1 #bdi1 #bgg1 #bgh1 #bhh2 ii4 #cf ,dirr+ton ,law1 i4 #bij ,dittm>1 ,pr(41 ii4 #acg ,dol]ite1 i4 #aai1 #acd1 #agh1 #aij1 #bjf1 #bcj1 #bdg1 #bfa1 #cgh1 #djc1 #djg1 #dag1 #ddh2 ii4 #e1 #aa1 #ce1 #di1 #ajb1 #ajc1 #ajd1 #abe1 #acf1 #aeg1 #ahc1 #bga1 #bii1 #cjc1 #cjg1 #cai1 #cbh ,dolgelli1 i4 #afi1 #agh1 #ahh ,donegal1 ,dalradian rocks (1 i4 #abb2 dykes 91 ii4 #abd ,drogh$a1 volcanic rocks ne>1 i4 #bdd ,duff91 ,w4 le ,s41 ii4 #dbf ,dumb>ton1 rocks ne>1 i4 #djb1 #djd ,dumfoyn1 a volcanic neck1 i4 #cie1 #cih1 #djj ,dumgoyn1 a volcanic neck1 i4 #cie1 #cig1 #cih1 #djj ,dundee1 sills & bosses ne>1 i4 #bib1 #cjf ,duneaton ,wat]1 volcanic rocks (1 i4 #cbi ,dunite1 ii4 #cji ,du ,noy]1 ,g4 ,v41 i4 #bde1 #bej1 #bed2 ii4 #bgb1 #dbf ,durham1 ,mr41 i4 #bge ,durness ,lime/one1 i4 #aab1 #aba1 #abc1 #ada ,du/1 volcanic1 i4 #ac ,dutton1 ,capt4 ,c4 ,e41 i4 #fh2 ii4 #bfg ,dykes1 vitre\s m>g9s (1 i4 #ah2 =mation (1 #ed1 #ih2 9 necks1 #ff2 fill$ ) agglom]ate1 #gj2 gr\p+ (1 among intrusive rocks1 #gg2 "* (1 #gi2 ext5t (1 9 ,brita91 #hj2 age (1 #ha2 comp\nd1 #ha2 ii4 #ei2 expulsion ( lava f1 i4 #hb2 ii4 #abh2 connect$ ) ! surface1 i4 #hb2 pre-,cambrian1 #aah2 fl[-/ructure 91 #afa2 ,cambrian1 #aef2 ,silurian1 #ahg1 #baf1 #bce1 #bcg1 #bdh1 #bdi2 ,old ,r$ ,s&/one1 #bgg1 #bia1 #cch1 #cde2 ,c>bonif]\s1 #djf1 #dbi1 #dfj2 ii4 #a1 #cj2 ,p]mian1 #hc2 amygdaloidal /ructure (1 #he ---- ,t]ti>y1 ii4 #aad2 argum5ts = _! geological age1 #aah1 #abe1 #aga2 geographical di/ribution1 #aba2 two types ( protrusion (1 #abb2 nature ( compon5t rocks (1 #abe2 ext]nal "* (1 #abf2 classification ( basic1 #abi2 enclos$ fragm5ts 91 #abi1 #aca1 #add2 porphyritic & amygdaloidal /ructures (1 #abh1 #abi1 #acj2 ve9s 91 #acj2 jo9ts 91 #acb1 #aff2 microscopic *>act]s (1 #acd2 *emical *>act]s (1 #acg1 #aci2 hade (1 #aci2 bread? (1 #aci2 int]ruptions (1 #adb2 l5g? (1 #adb2 p]si/5ce ( m9]al *>act]s (1 #add2 direction (1 #ade1 #aei2 upw>d t]m9ation (1 #adg2 kn[n v]tical ext5sion (1 #aej2 evid5ce ( movem5t ( molt5 rock (1 #aea2 bran*es & ve9s f1 #aeb2 connection ) sills1 #aee2 int]sect+1 #aeh2 comp\nd or ( m ?an "o infill+1 #aei2 d\ble1 treble1 & multiple1 #afj1 #cah1 #dag1 #dci2 comp\nd1 ) basic & acid b&s1 #afa1 #dce2 contact metamorphism (1 #afc2 relation (1 to geological /ructure1 #aff2 orig9 & hi/ory (1 #age2 ,icel&ic example (1 #bfa2 example communicat+ ) c9d] cone 9 ,utah1 #bfh2 connection (1 ) surface1 #agi1 #bfi1 #bhj2 late/ protrusions (1 #cha1 #djh1 #daf2 ( granophyre1 #dce1 #dcf1 #dcg1 #dci ,e>?1 condition ( ! int]ior ( !1 i4 #aj2 fractures 9 cru/ ( !1 #aa ,e>?quakes1 influ5ce (1 on e>ly man1 i4 #a2 transi5t effects (1 #c1 #h ,ea/ ,lo?ian1 tra*yte lavas (1 i4 #bd2 ,c>bonif]\s volcanic plateau (1 #cgj1 #chi1 #djc1 #dji ,ed9burgh1 volcanic rocks ne>1 i4 #bd1 #ajb1 #ajd1 #bfi1 #bgc1 #bgf1 #bgi1 #bha1 #bhe1 #bhg1 #bhi1 #bia1 #bic1 #caa1 #cag1 #cah1 #cbc1 #cfd1 #cgj1 #cgc1 #che1 #chf1 #chg1 #chi1 #daj1 #dbj1 #dcf1 #ddi ,egan1 ,mr4 ,f4 ,w41 i4 #bdb2 ii4 #bja1 #dbc ,eifel1 i4 #d1 #df1 #eh1 #ajj ,eigg1 ,isle (1 ii4 #aae2 pit*/one (1 #ahe1 #bag1 #bdb1 #dde2 brecciat$ basalt 91 #ahi1 #aib2 basalt plateau (1 #bae1 #bcd2 ,scuir (1 #bag1 #bcd1 #ddg2 sills (1 #cah2 acid bosses (1 #djc2 acid sills (1 #dca2 pro(s ( subsid5ce at1 #ddg2 enorm\s d5udation (1 #bci1 #ddg1 #deh ,eildon ,hills1 i4 #cge ,electric ,peak1 i4 #gi1 #hb1 #hd ,elvans1 i4 #bdi1 #bha ,engulphm5t crat]s1 i4 #eh ,enn]dale1 granite (1 i4 #bcf ,enniscor?y1 volcanic rocks ne>1 i4 #bde ,environm5t1 influ5ce (1 on e>ly man1 i4 #a ,eozoic p]iod1 i4 #aaj ,epidiorite1 i4 #aah1 #abd1 #abi1 #ahd1 #bdg1 #bdi ,erosion1 laws (1 i4 #aja ,eruptions1 transi5t effects (1 i4 #c2 old subm>9e1 h[ asc]ta9$1 #dh2 lacu/r9e1 #di2 fluviatile1 #di2 t]re/rial1 #ej2 evid5ce ( int]vals betwe51 #bhc1 #bhg1 #cjj1 #ddb2 ii4 #db1 #ei1 #bjc1 #bje1 #bba1 #bea1 #bed1 #bhg ,erz]\m1 old volcanoes ne>1 i4 #cb ,eskdale ,dyke1 ii4 #abg1 #acc1 #acf1 #acg1 #adj1 #adc1 #ade1 #adf1 #aec ---- 7,lake ,di/rict71 granite (1 i4 #bcf ,e!ridge1 ,mr4 ,r1 jun41 ii4 #bd ,etna1 i4 #b1 #d1 #aj1 #ee2 ii4 #bfa ,eurite1 i4 #ahh ,europe1 basalt plateaux ( nor?-we/]n1 i4 #ea1 #eb2 ii4 #aha2 pre-,cambrian di/urbances ( nor?-we/]n1 i4 #aag ,explosion-crat]s1 i4 #eh2 ii4 #bff ,explosions1 volcanic1 i4 #bdf2 ii4 #aif1 #bff1 #dbe1 #dgb ,extrusive rocks1 def9$1 i4 #ad2 textures (1 #gh ,fair ,head1 sills (1 ii4 #cja ,f>ey1 ,j41 ii4 #i ,f>ne ,isl&s1 ii4 #b ,f>oe ,isles1 basalt plateaux (1 i4 #eb1 #ajb2 ii4 #aia1 #aib1 #aid1 #bef2 v5ts 91 i4 #fc2 ii4 #bic2 dykes (1 #abb1 #acc2 tuffs & lignites (1 #beh2 sills (1 #cbb2 abs5ce ( gabbro bosses 91 #cee2 subsid5ce (1 #ddg2 dip ( basalts 91 #ddh2 pro(s ( d5udation 91 #deh ,faujas ,/4 ,fond1 ii4 #aji1 #aab ,faults1 connexion ( volcanic v5ts )1 i4 #fi2 ii4 #fe2 b\nd>y1 i4 #bid1 #cjc1 #cje1 #cfi2 ii4 #afi2 effects (1 i4 #ddf2 ii4 #bjj2 connection )1 dykes1 #afh ---- ( ,t]ti>y basalt-plateau1 ii4 #deb ,felsite 7,fel/one71 ,torridonian1 i4 #abj2 ,uriconian1 #acj1 #acc2 ( ,malv]ns1 #acd2 ,cambrian1 #aea1 #afj1 #afa1 #afd1 #afe1 #afg1 #afh2 ,silurian1 #ahd1 #aii1 #bje1 #bjf1 #bjg1 #baj1 #bab1 #bah1 #bca1 #bcb1 #bdf1 #bdg1 #beb1 #bee2 ,old ,r$ ,s&/one1 #bgf1 #bgg1 #bia1 #bic1 #cba1 #cbg1 #cce1 #cdf2 ,c>bonif]\s1 ii4 #cf1 #di2 ,p]mian1 #he2 ,t]ti>y1 #agd1 #cfi1 #dbd1 #ddf ,felsitic breccia1 ii4 #aie ---- type ( devitrification1 i4 #ai ,felsp>1 eject$ cry/als (1 i4 #aha2 ii4 #eh1 #gi2 l>ge porphyritic cry/als (1 9 dykes1 #abi1 #ace ,fife1 ,old ,r$ ,s&/one volcanic rocks (1 i4 #cjg2 ,c>bonif]\s volcanic rocks (1 #dbh1 #dbi1 #dcj1 #dcc1 #dcg1 #ddh2 ,p]mian volcanic rocks (1 ii4 #ef1 #fi ,f+al's ,cave1 i4 #be2 ii4 #baj ,fi%]1 ,rev4 ,o41 i4 #ih ,fi%gu>d1 volcanic rocks at1 i4 #bje ,fissure type ( volcanoes1 i4 #db1 #eb2 ii4 #ajh1 #aae1 #bfg ,fissures1 volcanic1 i4 #db1 #eb1 #ec1 #ed1 #dbe2 ii4 #ada1 #ade1 #aei1 #agf2 fill$ ) agglom]ate1 i4 #gj2 fill$ ) dykes1 #ha1 #aah2 comp\nd1 #hb1 ii4 #aei2 pre-,cambrian1 i4 #aah1 #aai2 ,c>bonif]\s1 #dbe2 ,t]ti>y1 ii4 #ada1 #aei1 #agf1 #dbe2 mod]n ( ,icel&1 #bfb2 cause (1 #agg ,flem+1 ,john1 i4 #bfh ,fl[-/ructure1 i4 #ba1 #aeg1 #afj1 #afa1 #afb1 #ahd1 #baj1 #bcb1 #bdf1 #bdh1 #bee1 #cae1 #cba1 #cbg1 #cdf2 ii4 #abi1 #aeb1 #aij1 #aia1 #ccb1 #cfi1 #cib1 #djb1 #dbd1 #dcg1 #dda ,foot1 ,f4 ,j41 i4 #caf ,=bes1 ,d41 ii4 #cgj ---- ,edw>d1 ii4 #ff1 #aac1 #aad1 #aih ---- ,j4 ,d41 ii4 #aab1 #ccc1 #cgb1 #cha ,=ell5/e91 ii4 #ccb ,=e/ ( ,wyre coal-field1 ii4 #ajb ,=f>%ire1 volcanic rocks (1 i4 #bhe1 #bii2 flag/ones (1 #bii ,=/]1 ,m41 ii4 #aac ,=?-bas91 ,c>bonif]\s sy/em (1 i4 #cfa2 ,c>bonif]\s plateaux (1 #cgj2 ,c>bonif]\s puys (1 #daf1 #dbg1 #dbi1 #dcj1 #dcb1 #dcd1 #dcg1 #ddj1 #ddf1 #dfb2 ,p]mian volcanoes (1 ii4 #ee1 #fg ,fo/]1 ,mr4 ,c4 le ,neve1 ii4 #aj ,f\qu1 ,pr(41 i4 #ah1 #ba2 ii4 #acd ,fox1 ,mr4 ,h[>d1 ii4 #cf ,fox ,/rangways1 ,mr4 ,c41 i1 #ace ,fragm5tal volcanic rocks1 i4 #ad2 only arise f explosions :i* rea* ! surface1 #eg 7see ,agglom]ates1 ,conglom]ates1 ,tuffs7 ,france1 ,t]ti>y volcanoes ( ,c5tral1 i4 #d1 #aj1 #bi1 #da1 #de1 #di1 #eh1 #fj1 #gj2 ii4 #ca1 #bga1 #bha1 #cgc2 ,c>bonif]\s volcanic action 91 i4 #ceg ,frankl&1 ,pr(4 ,e41 i4 #bgc1 #bgh ,fundam5tal complex ( olde/ gneiss1 i4 #aad1 #aae ---- gneiss1 i4 #aae ,gabbro1 granulitic1 ii4 #cbi2 b&$ /ructure (1 i4 #aaf2 ii4 #cbi1 #ced1 #ceg1 #dgf2 co>se-gra9$ massive1 #ccj2 pale v>ieties 9 ve9s1 #ccj2 gneiss-l aspect (1 #cdb1 #bed1 #ceh ---- ( ,c>rock ,fell1 i4 #ia2 ,silurian1 #aie1 #bjf1 #bdg2 ,devonian1 #bfb2 ,t]ti>y1 #hd1 #ij1 #aaf2 ii4 #cjg1 #cjh1 #cji1 #cai1 #cbg1 #ccd1 #cdi1 #cee1 #ceh1 #cia1 #djf1 #djg ,gairlo*1 peculi> pre-,cambrian rocks (1 i4 #aae1 #aag ,galapagos ,isl&s1 i4 #bg ,galla/on type ( dol]ite & basalt1 i4 #dah ,gall[ay1 granites (1 i4 #ic1 #ie1 #bgb1 #bgg1 #bij1 #cca ,g>abol ,hill1 diff]5tiation at1 i4 #ij ,g>d9]1 ,miss1 i4 #ie ,g>d9]1 ,mr4 ,c4 ,j41 i4 #bef ,g>dn]1 ,mr4 ,/>kie1 ii4 #aif1 #aih1 #bab ,g>lton ,hills1 i4 #ajb1 #cgj1 #cgg1 #cgh1 #cgi1 #chj1 #chf1 #cij1 #dje1 #dab ,g>net f\nd 9 volcanic v5ts1 i4 #fb ,g>? ,grit1 i4 #agg1 #ahe1 #bjh ,gases dissolv$ 9 ! volcanic magma1 i4 #ac1 #ae1 #gb1 #ig1 #ii ,geikie1 ,pr(4 ,j41 i4 #bgg1 #cjf1 #cjh1 #cca1 #ccf1 #cci1 #cdj1 #cfi1 #cge1 #dbf2 ii4 #eg1 #aia1 #bei1 #cbb ,g5vre1 ,mont1 i4 #aid ,geological action1 suppos$ =m] great] int5sity (1 i1 #aci ---- contra/s1 i4 #ajc ---- hi/ory1 i4 #aji1 #aac ---- ,survey ( ,great ,brita91 i4 #aac1 #aae1 #aah1 #aai1 #aba1 #abb1 #abc1 #abd1 #abe1 #abf1 #abi1 #acj1 #acc1 #ace1 #adb1 #adc1 #add1 #ade1 #aei1 #afj1 #aff1 #agj1 #aga1 #age1 #agf1 #agi1 #aha1 #ahb1 #ahc1 #ahf1 #ahg1 #ahh1 #aij1 #aif1 #aih1 #bja1 #bjd1 #bje1 #bjg1 #bjh1 #bab1 #bad1 #bae1 #baf1 #bag1 #bah1 #bai1 #bbj1 #bba1 #bbe1 #bbg1 #bbh1 #bcb1 #bcc1 #bch1 #bci1 #bdj1 #bdb1 #bdc1 #bdd1 #bde1 #bej1 #bea1 #bed1 #bei1 #bgj1 #bge1 #bgh1 #bid1 #bii1 #cjf1 #cjg1 #cjh1 #cad1 #cae1 #cag1 #cah1 #cbe1 #cbi1 #cca1 #ccf1 #cci1 #cdj1 #cdd1 #cdf1 #cdi1 #cej1 #ceb1 #cfd1 #cfi1 #cgb1 #cgc1 #cge1 #cig1 #djc1 #djd1 #djf1 #djg1 #daa1 #dbc1 #dbe1 #dcd1 #ddi1 #dfb1 #dge1 #dgf2 ii4 #c1 #d1 #i1 #aj1 #ab1 #ac1 #af1 #ag1 #bj1 #bc1 #cc1 #cf1 #cg1 #db1 #dc1 #df1 #dh1 #di1 #ef1 #eh1 #fe1 #ff1 #fh1 #id1 #ie1 #ajb1 #ajc1 #aah1 #aba1 #abe1 #abg1 #add1 #ade1 #adh1 #afb1 #afd1 #agj1 #agd1 #age1 #aij1 #aib1 #aii1 #bja1 #bjc1 #bec1 #bgb1 #bgg1 #bib1 #cdg1 #chd1 #cia1 #dbj1 #dbb1 #dbc1 #dbf1 #dbh1 #dcc1 #dce1 #ddf1 #ddi ,giant's ,causeway1 ii4 #hj1 #aji1 #ahf1 #ahh1 #aib1 #bjf ,gilb]t1 ,mr4 ,g4 ,k41 i4 #hg2 ii4 #cfb1 #cfc ,girvan1 i4 #aib1 #bjj ,glaciation1 abs5ce (1 9 ,devon%ire1 i4 #bfa ,glass 9 volcanic rocks1 i4 #ah1 #cc1 #fj1 #gh1 #ahj1 #baa1 #baf1 #bcj1 #bcb1 #bce1 #caf2 ii4 #he1 #abj1 #abf1 #acc1 #ace1 #acg1 #ahd1 #bjd1 #bdg1 #bgb1 #bhe1 #caf1 #cag ,globulites1 ii4 #ace ,gl\ce/]%ire1 ,silurian volcanoes (1 i4 #bch ,gneiss1 analogies (1 ) igne\s rocks1 i4 #ic2 ii4 #dgf2 olde/1 i4 #aaj1 #aae ,godw9-,au/51 ,a4 ,c41 i4 #bei1 #bfb ,good*ild1 ,mr4 ,j4 ,g41 i4 #bbi1 #ddi2 ii4 #aej ,gra+]1 ,rev4 ,dr41 ii4 #aih ,gr& ,s>c\i1 ii4 #cgc1 #cgd1 #cha ,granite1 bosses (1 i4 #hh1 #ij1 #ic2 plutonic & volcanic1 #hi2 metamorphism by1 #ie2 alt]$ by dykes1 ii4 #afd2 pre-,cambrian1 i4 #aai2 po/-,ar5ig 9 ,highl&s1 #abf1 #caj2 9 ,cambrian rocks1 #aee2 9 ,silurian rocks1 #bjj1 #bbi1 #bcf1 #bch1 #bdi2 ( probably ,old ,r$ ,s&/one age1 #bgb1 #bgg1 #bij1 #cca1 #ccg2 ,t]ti>y1 ii4 #cff1 #dah1 #dbj ,granitite1 i4 #ahh1 #bgg1 #bij1 #ccg2 ii4 #cfg ,granophyre1 alt]ation ( rocks by1 i4 #ie1 #if2 sc5]y (1 #aje2 solv5t action (1 #hb1 #hd1 #he1 #if1 #ii2 ii4 #afc1 #cib1 #dae1 #dbb1 #dcc2 brecciat$1 #chb2 sph]ulitic1 #cha2 b$d$ /ructure (1 #cha1 #djc1 #djd2 apt to be intrud$ at ! base ( a volcanic s]ies1 #djc2 %att]+ ( rocks invad$ by1 #dje1 #daa1 #dac1 #daf1 #dci2 ve9s (1 #dji1 #daj1 #dcb1 #dcg2 ,silurian1 i4 #bad1 #bae ---- ,t]ti>y1 i4 #cci2 ii4 #cfh1 #cie1 #djh1 #dcj2 b\nd>ies (1 #chb1 #dji2 relation to old] v5ts1 #bhj1 #chd1 #cii2 relation to plateau-basalts1 #chf1 #cif1 #djb1 #djd2 relation to gabbro1 #cia1 #djb1 #djd1 #daj2 relation to basic dykes1 #cie2 pro( ( liquidity (1 #dac2 sills (1 #dcj1 #dcf1 #dcg2 dykes (1 #dce ,granophyric /ructure1 i4 #bj2 ii4 #cff ,graphite 9 ,t]ti>y volcanic s]ies1 ii4 #aih ,graptolites1 i4 #agd1 #aif1 #aig ,grauwacke or ,devonian rocks1 ,de la ,be*e on1 i4 #bei1 ii4 #cc ,graves1 ,lieut4 ,t41 ii4 #dea ,great ,gl5 ( ,scotl&1 i4 #aba ,greeks1 influ5ce ( volcanoes on1 i4 #a ,gre51 ,a4 ,h41 i4 #acc1 #acd1 #afc2 ii4 #aj1 #ab ,gre5l&1 ,t]ti>y basalts (1 ii4 #ahb ,gre5ly1 ,mr4 ,e41 i4 #abi1 #bad ,gre5ock1 ,"l1 i4 #cfc ,gre5 s*i/s ( ! ,scotti% ,highl&s1 i4 #abb2 ( ,anglesey1 #abi ,gre5/one1 i4 #ahc1 #ahg1 #bjf1 #bag1 #bai1 #bdi1 #bei1 #bfa2 ii4 #cd1 #ce1 #cg1 #ajc1 #ajd1 #cee ,gre5/one-a%1 i4 #bai ,griffi?1 ,sir ,r41 ii4 #bii1 #dbb ,gunn1 ,mr4 ,w41 i4 #aad1 #bih1 #caa1 #ccf1 #cfi1 #djg1 #daj2 ii4 #eh1 #agb1 #dbj ,gypsum deposits1 ii4 #ed ,hade ( dykes1 ii4 #aci ,hmatitic iron-ore1 ii4 #aig ,hall1 ,sir ,james1 i4 #gb1 #cfc ,hllefl9ta1 i4 #aca1 #afg ,h>dman1 ,e4 ,t41 ii4 #cfe1 #ddi ,h>k]1 ,mr4 ,a41 i4 #ij1 #ia1 #ic1 #ie1 #if1 #ii1 #ahh1 #bji1 #baj1 #baa1 #bab1 #bac1 #bad1 #bag1 #bah1 #bbb1 #bbg1 #bbh1 #bcj1 #bca1 #bcb1 #bce1 #bcf1 #bcg1 #bch1 #bij2 ii4 #abd1 #abe1 #abf1 #abi1 #acj1 #aci1 #add1 #adf1 #afj1 #afb1 #afc1 #afd1 #agd1 #ahe1 #ahi1 #aij1 #bbc1 #bbd1 #bdg1 #bfi1 #bha1 #bhd1 #bhe1 #cji1 #caj1 #cah1 #cbj1 #ccd1 #cci1 #cdg1 #cdh1 #cfh1 #chb1 #chd1 #che1 #chg1 #chi1 #cib1 #djg1 #djh1 #dji1 #dac1 #dae1 #dcc1 #dcd1 #dcg1 #dda1 #ddf ,h>kness1 ,r41 i4 #bbh2 ii4 #ef ,h>le* anticl9e1 i4 #aei1 #agi1 #ahg2 gr\p1 #agf ,hat*1 ,dr4 ,f4 ,h41 i4 #ahc1 #ahd1 #ahg1 #ahh1 #bbi1 #bcj1 #bdf1 #bdg1 #bdh1 #bdi1 #bfa1 #bgg1 #bgh1 #cjf1 #cgg1 #chj1 #cha1 #dag1 #dai1 #dbj2 ii4 #eg1 #if1 #ahd1 #bgd1 #bgf1 #bii1 #cai1 #ccb1 #cfg1 #cfh1 #cfi1 #cgj1 #chh1 #cih ,haughton1 ,pr(4 ,s41 i4 #cdf2 ii4 #dbb ,hawaii1 lava-f\nta9s (1 i4 #ab2 diff]5tiation 9 lavas (1 #bg2 lava-cauldron (1 #eh ,hawor?1 ,mr4 ,e41 ii4 #if ,hay ,cunn+ham1 ,r4 ,i41 i4 #bfi1 #cag1 #cfc1 #cgb1 #cgc1 #ddi1 #dea2 ii4 #bcg1 #bch1 #bdd ,heaphy1 ,mr4 ,c41 i4 #dcb ,hebrides1 basalt-%eets (1 i4 #bd1 #dg1 #eb1 #ajb2 acid rocks (1 #ie1 #ajb2 gabbros (1 #hd1 #ij1 #ajb2 sc5]y (1 #aje2 pre-,cambrian rocks (1 #aab1 #aad1 #aag1 #aba2 ,cambrian l& (1 #ada2 e>ly obs]vations on ! ,t]ti>y volcanic rocks (1 ii4 #aji1 #aaj1 #aaa2 dykes (1 #aah1 #adf1 #aeh1 #agd2 basalts (1 #aha1 #ahf1 #bae2 pit*/one lava (1 #bch1 #bdf2 plateau-sc5]y (1 #bdi2 ,t]ti>y riv]s & lakes (1 #bag1 #bbh1 #bca1 #bcd1 #beb2 v5ts (1 #bgd2 basic sills (1 #cjd2 gabbro intrusions (1 #cbg2 acid intrusions (1 #cfd1 #cgi1 #dcj1 #dcg2 dislocations (1 #deb2 d5udation (1 #dee ,h$dle1 ,dr41 i4 #bgd1 #cjb2 ii4 #gh1 #gi1 #bdf1 #cjg1 #djf ,hell&1 ,pr(4 ,a41 ii4 #aia1 #bfa1 #bfc1 #bfd ,h5d]son1 ,mr4 ,j41 i4 #ddi ,h5ry ,m\nta9s1 laccolites (1 i4 #hf2 ii4 #cfb ,h5sl[1 ,j4 ,s41 ii4 #bb1 #bbd ,het]og5eity 9 volcanic magmas1 i4 #he1 #ij2 ii1 #aij1 #ccd ,hett ,dyke1 ii4 #a1 #g1 #adg ,hibb]t1 ,s41 i4 #df ,hicks1 ,dr4 ,h41 i4 #abf1 #ade1 #aed1 #aeh1 #aei1 #aff1 #bjf ,hill1 ,mr4 ,j4 ,b41 ii4 #adj ,hill1 ,rev4 ,e41 i4 #ace ,h9de1 ,dr4 ,g4 ,j41 i4 #aih2 ii4 #ce ,h9xman1 ,mr4 ,l41 i4 #aad1 #cdd2 ii4 #aba ,hobson1 ,mr4 ,b41 i4 #bfj2 ii4 #bc1 #bg1 #if1 #ii ,hold51 ,mr4 ,j4 ,s41 ii4 #bjd ,holl1 ,h4 ,b41 i4 #acc1 #acd1 #agj ,holl&1 ,mr4 ,p41 i4 #agg1 #agh1 #agi2 ii4 #bc ,hollybu% ,s&/one1 i4 #acc1 #agj ,holocry/all9e /ructure1 i4 #gh2 ii4 #acf1 #ahd ,hopk9s1 ,w41 ii4 #agg1 #agi1 #bfh ,hornbl5de1 eject$ cry/als (1 i4 #agh1 #aha2 ii4 #di1 #ea1 #eh1 #gi ,hornbl5de-s*i/s =m$ f basic igne\s rocks1 i4 #ge1 #aad1 #aah1 #aai1 #abd1 #abi ,horne1 ,mr4 ,john1 i4 #aad1 #aif1 #aii1 #bjj1 #cdd1 #cde1 #cge2 ii4 #bc1 #add1 #bib ,hornito ( a lava-/ream1 i4 #ee2 ii4 #bfd ,horn/one1 i4 #aca1 #acf1 #bgg1 #bgh 7analyses71 #cbd ,h\/on ,m>ls1 i4 #dbc1 #dcf1 #ddj1 #ddd1 #dff ,h[>d1 ,mr4 ,h4 ,t41 i4 #bjg ,h[ell1 ,mr4 ,h4 ,h41 i4 #bid1 #cjg1 #cfd ,hoy1 ,isl& (1 i4 #cej ,hughes1 ,pr(4 ,t4 ,m',k41 i4 #abf1 #add1 #afj1 #afa1 #aff1 #afh1 #bbj1 #bbb1 #bbc1 #bbg ,hull1 ,mr4 ,e41 ii4 #db1 #ie1 #ajc1 #bgb1 #dba1 #dbf1 #ddi ,hurlet ,lime/one1 i4 #cfj1 #cff1 #cid1 #daj1 #dae1 #ddd1 #deb1 #def1 #dfg1 #dgj1 #dgd ,huronian rocks1 i4 #aaa ,hut*+s1 ,mr4 ,w4 ,m41 i4 #bbg1 #bcj1 #bcc ,hutton1 ,james1 i4 #cfc2 ii4 #i1 #aaj ,hutton1 ,w41 ii4 #c ,hyp]ite1 i4 #bgi ,hysgeir1 pit*/one (1 ii4 #bdf ,icel&1 ,t]ti>y basalts (1 ii4 #ahb1 #bfj2 ,t]ti>y gabbros & lip>ites or granophyres (1 #bfa2 cont9uity ( volcanic ph5om5on (1 #bfa2 lava-fields (1 i4 #bd1 #db1 #ec1 #ajj2 ii4 #bfj2 lava-domes (1 i4 #aj2 ii4 #bfe2 fissures (1 i4 #gj2 ii4 #bfb1 #bga1 #ded2 dykes (1 #abb1 #bfa2 c9d] cones (1 #bfd1 #bga2 subsid5ce (1 #ddg ,idaho1 lava-fields (1 ii4 #bfg ,idd+s1 ,pr(41 i4 #bh1 #bi1 #cj1 #gh1 #gi1 #hb1 #hd1 #ij2 ii4 #abh1 #agh ,idiomorphic cry/als1 i4 #ba1 #dag1 #dbj2 ii4 #dj ,index ,lime/one ( ! ,scotti% coal-fields1 i4 #cfj1 #ddd1 #deb ,india1 fissure-eruptions (1 i4 #aj2 volcanic plateau (1 ii4 #ahj ,int]m$iate volcanic rocks1 silica-p]c5tage (1 i4 #ad ,int]s]tal /ructure1 i4 #dag2 ii4 #acf ,intrusive rooks1 def9$1 i4 #ad2 occasional cellul> "* (1 #af2 fl[-/ructure 91 #bb1 #afa2 v>ieties (1 #gg2 textures (1 #gh1 #ddi2 ii4 #bgd1 #cfj1 #cib2 9 %eets1 sills1 & laccolites1 i4 #hc2 melt+ ( rocks by1 #hb1 #hd2 ii4 #abi1 #afc1 #cib2 consolidation (1 i4 #hd2 b&+ (1 #hd1 #dej2 ii4 #cbi1 #cdb2 het]og5eity (1 i4 #he2 ii4 #cdd2 metamorphism by1 i4 #id1 #dea2 influ5ce ( surr\nd+ rocks on1 #ie2 conditions ( _! intrusion1 #ig2 column> /ructure 91 ii4 #ahg1 #bia1 #cja ---- ,pre-,cambrian1 i4 #aaf2 ,cambrian1 #aef2 ,silurian1 #ahg1 #aie1 #bjf1 #baf1 #bce1 #bcg1 #bdh1 #bdi2 ,devonian1 #bfa2 ,old ,r$ ,s&/one1 #bgg1 #bia1 #cba1 #cce1 #cch1 #cdc1 #cde2 ,c>bonif]\s1 #djf1 #djh1 #dbj1 #ddf2 ii4 #a1 #ba1 #cj1 #cc1 #dj1 #dh2 ,p]mian1 #eh1 #fd2 ,t]ti>y1 #bgj1 #bih ,irel&1 subm>9e eruptions (1 i4 #dh2 ,dalradian rocks (1 #abb1 #abc1 #abf2 ,ar5ig rocks 91 #abc2 ,silurian volcanic rocks (1 #bci1 #bea2 granites (1 #bij2 ,old ,r$ ,s&/one volcanic rocks (1 #cdf1 #cdh2 ,c>bonif]\s volcanic rocks (1 #cei2 ii4 #cg2 e>ly obs]v]s among ! ,t]ti>y volcanic rooks (1 #aji2 ,t]ti>y basalt plateau (1 #cfd1 #cgj1 #cga2 gabbros (1 #cei2 acid rocks (1 #dbj ,iron-ore1 pisolitic 7,ar5ig71 i4 #aha1 #bjh2 ,t]ti>y1 ( ,antrim1 ii4 #bjd ,irv9e1 ,mr4 ,d4 ,r41 i4 #bid1 #bii ,irv+1 ,rev4 ,a41 ii4 #ie ,isogeo!rms1 %ift+ (1 i4 #ih ,italy1 old volcanoes (1 i4 #d2 ii4 #dgd1 #dgg ,jack1 ,mr4 ,r4 ,l41 i4 #bid1 #cjh1 #cfi1 #cge1 #cif1 #djd2 ii4 #eg1 #ade ,jameson1 ,rob]t1 i4 #bfh1 #bfi1 #cag1 #cfc2 ii4 #aji1 #afa1 #bdd1 #ccc1 #cee1 #cfd ,jan ,may51 ii4 #ahb ,j$burgh type ( dol]ite & basalt1 i4 #dah ,j5n+s1 ,mr4 ,c4 ,v41 i4 #agf1 #agg1 #agi1 #ahj1 #aha1 #ahd1 #ahe1 #ahf1 #ahg1 #ahh ,john/on-,lavis1 ,dr41 ii4 #bfa ,jo9ts 9 dykes1 ii4 #acb ,judd1 ,pr(4 ,j4 ,w41 i4 #aeg1 #bge2 ii4 #aae1 #aaf1 #acd1 #acg1 #afb1 #ahe1 #bji1 #baa1 #bde1 #bdg1 #bfg1 #bgd1 #bgh1 #bhj1 #cjc1 #cjg1 #cji1 #cae1 #caf1 #cai1 #cbb1 #cbh1 #cbi1 #ccb1 #ccc1 #cdi1 #cef1 #cfj1 #cgb1 #chh1 #daj1 #dci ,jukes1 ,j4 ,b41 i4 #adc1 #aga1 #age1 #bjh1 #bah1 #bai1 #bde1 #bdf1 #bej1 #bed1 #caf2 ii4 #aj1 #bj1 #db1 #dg1 #di1 #aja1 #ajc1 #aje ,jurassic p]iod1 physical conditions ( !1 ii4 #ajh1 #ahb ,kelly1 ,j41 i4 #cad ,k5m>e1 ,old ,r$ ,s&/one volcanic rocks (1 i4 #cej ,k]atophyre1 i4 #bdg ,k]r]a1 ,isle (1 i4 #cdb ,k]santite1 i4 #bfa ,keswick1 i4 #bbi ,kild>e1 ,*air (1 ,bala volcanic rocks at1 i4 #bde1 #bef ,kill>ney1 nodul> lavas (1 i4 #bj1 #bgb1 #cdf ,kilpatrick ,hills1 i4 #che1 #chh1 #djc1 #daj ,kilroe1 ,mr4 ,j4 ,r41 i4 #bea1 #bec1 #cae ,kilsy? type ( dol]ite & basalt1 i4 #dah ,k9ahan1 ,mr4 ,g4 ,h41 i4 #cdi2 ii4 #de1 #di1 #dbf ,k9c>d9e%ire1 volcanic necks (1 i4 #bha1 #bhf1 #bic1 #bii2 ,old ,r$ ,s&/one (1 #cja ,k+1 ,mr4 ,cl>5ce1 i4 #bg ,k+'s ,c\nty1 volcanic necks (1 ii4 #cg ,kippie ,law type ( basalt1 i4 #dah ,kirkby1 ,mr4 ,j41 ii4 #ajf ,kirwan1 ,r41 ii4 #aaj ,knockfe]9a1 ,old ,r$ ,s&/one volcanic rocks (1 i4 #cdi ,knocklayd1 ii4 #bjj ,kyna/on1 ,mr4 ,h41 i4 #cdc ,labyr9?odonts1 i4 #cef ,laccolites1 i4 #gg1 #hc1 #hf1 #hh1 #ih1 #ii1 #aij2 ii4 #cfc ,lacroix1 ,pr(41 i4 #if ,lacu/r9e volcanic eruptions1 i4 #di ,lagorio1 ,dr4 ,a41 ii4 #acg ,lake1 ,mr4 ,p41 i4 #agg1 #agi ,lake-,di/rict1 i4 #bbg1 #bij2 ,vesuvian cone (1 i4 #db1 #de ,lake ,cal$onia1 i4 #bgb1 #bid1 #bif ,lake ( ,lorne1 i4 #cda ,lake ,orcadie1 i4 #bff1 #bga1 #cdc1 #cej ,lakes1 eruptions 91 i4 #di2 crat]1 #eh2 ( ,old ,r$ ,s&/one1 #bfd ,lambay ,isl&1 conglom]ates (1 i4 #bdd ,lamm]muir1 granites (1 i4 #bij1 #cdj ,lamplugh1 ,mr4 ,g4 ,w41 i4 #cb1 #bbj2 ii4 #bc1 #bh ,lamprophyre1 i4 #bia1 #bic ,lan>k%ire1 i4 #bia1 #cfh1 #daf ,l&1 sculpture ( !1 i4 #aja1 #ajb ,l&slips1 ii4 #bjj1 #bhg ,lanke/]1 ,pr(4 ,e4 ,ray1 i4 #caj ,lapilli1 volcanic1 i4 #cc1 #cd1 #fa1 #aea ,lapwor?1 ,pr(4 ,c41 i4 #acj1 #acb1 #acg1 #aga1 #agb1 #ahi1 #aij1 #aif ,l>gs1 volcanic v5t ne>1 i4 #ef1 #cif1 #cig1 #dja ,lasaulx1 ,pr(4 von1 ii4 #cfe1 #cga1 #dbf ,laur5tian gneiss1 i4 #aaj ,lavas1 classification (1 i4 #ad2 fl[-/ructure (1 #af1 #ba2 vesicul> /ructure (1 #ag2 glass 91 #ah2 devitrification (1 #ai2 b$d+ (1 #bd2 effect ( wat] on molt51 #be1 #ccd2 sack-l or pill[-/ructure (1 #bf1 #ahd1 #aic1 #bja1 #bdj1 #bdd1 #beb2 seldom occur 9 solit>y %eets1 #bf2 v>iations 9 /ructure 91 #bg2 sequ5ce (1 9 eruptions1 #bh1 #ib1 #cgg1 #chf2 cru/s (1 disrupt$ 9 volcanic explosions1 #eh1 #ei1 #fj2 ii4 #ahi2 alt]nations ( acid & basic1 i4 #bh1 #fa1 #aeb1 #aeg1 #afe1 #bjg1 #bac1 #bhd1 #cah2 ii4 #bcf1 #bff2 contra/$ ) intrusive rocks1 i4 #gh2 s&/one ve9s 91 #bhc1 #cjj1 #cjc1 #cbj1 #cbg1 #ccc1 #ccg2 ii4 #ei1 #ih2 %att]$ or agglom]ate /ructure (1 #ii2 metamorphism (1 i4 #bca1 #bdj1 #cch2 ii4 #bgb1 #bgf1 #ccg1 #cci1 #cdj1 #cdg1 #cee1 #cgi1 #chf1 #cig1 #cii1 #djj1 #djd1 #dac ---- ,cambrian1 i4 #aeb1 #afh ---- ,silurian ( ,m]ione?%ire1 i4 #ahc2 ,scotl&1 #aia2 ,buil?1 #bjc2 ,pembroke%ire1 #bje2 ,ca]n>von%ire1 #bjg2 ,b]wyn ,hills1 #bah2 ,anglesey1 #bai2 ,lake ,di/rict1 #bbg2 ,gl\ce/]%ire1 #bch2 ,irel&1 #bci1 #bed ---- ,l[] ,old ,r$ ,s&/one1 i4 #bgc1 #bha1 #bid1 #cag ---- ,c>bonif]\s1 i4 #cgg1 #chd1 #dag1 #dcf1 #ddj1 #ddc2 ii4 #h1 #ah1 #cd1 #de ---- ,p]mian1 ii4 #fh1 #if ---- ,t]ti>y1 ii4 #ahc2 types (1 #ahf2 b&+ (1 #ahi2 ?ickness (1 #aib2 l5ticul> "* (1 #aic2 ( ,antrim1 #aii2 irregul> b$d+ ( ! vitre\s1 #bdc ---- mod]n ,icel&ic eruptions (1 ii4 #bfa ,lava-domes1 ii4 #bfe ,lava-plug ( volcanic funnels1 p]man5ce (1 i4 #dj1 #da1 #ee1 #gc1 #gf1 #dcj ,lawson1 ,pr(4 ,a4 ,c41 i4 #hb ,leaf-b$s1 ii4 #aih ,leb\r1 ,pr(41 i4 #ccf2 ii4 #b1 #c1 #e1 #g ,leck/one1 i4 #dai1 #ddb1 #ddc ,lecoq1 ,h41 i4 #de2 ii4 #cgc ,le9/] granite1 ii4 #bde1 #bdi1 #bij ,lewisian ,gneiss1 i4 #ha1 #aaj1 #aaa1 #aac1 #aah ,liddesdale1 ,c>bonif]\s volcanic v5ts (1 i4 #ee1 #daf1 #dbe1 #ddj1 #dge ,life1 e>lie/ traces (1 i4 #adj ,lignite 9 ,t]ti>y volcanic s]ies1 ii4 #aih ,limburgite1 i4 #cgg1 #djh1 #dag1 #dbj1 #ddh2 ii4 #dj1 #df ---- type1 i4 #dah ,lim]ick1 ,c>bonif]\s volcanic rocks (1 i4 #dba1 #dcj2 ii4 #da2 ,old ,r$ ,s&/one volcanic rocks (1 i4 #cdh ,lime/one1 metamorphism (1 i4 #gb1 #dea2 ii4 #ad1 #bb1 #afd1 #bhj1 #chc ,l9dley & ,hutton on ,eigg conif]1 ii4 #bch ,l+ula ,flags1 i4 #add1 #agg ,l9li?g[%ire 7see ,we/ ,lo?ian7 ,l9tra!n1 porphyry (1 i4 #bgg1 #bib1 #caa ,lion's haun* type ( dol]ite & basalt1 i4 #dah ,li?om>ge1 ii4 #aig1 #bjd ,liz>d1 rocks at !1 i4 #aid ,llanb]is1 ,pass (1 i4 #aei1 #afc ---- gr\p1 i4 #add ,ll&eilo gr\p1 i4 #age1 #aif1 #bdb2 volcanic rocks (1 #ahf1 #bjb1 #bba1 #bbg1 #bda ,ll&e9iol51 i4 #afj ,ll&ov]y gr\p1 i4 #age1 #aif2 possible volcanic rocks (1 #bch ,llangadock1 i4 #bje ,llangefni1 i4 #bbj ,llanllyfni1 i4 #afa ,llanwrtyd1 i4 #bjd ,lleyn ,p59sula1 i4 #bjh1 #bji1 #bac1 #bae ,lloyd ,morgan1 ,pr(41 i4 #ade1 #adg1 #aed ,llyn ,pad>n1 i4 #aeg1 #aei1 #afj ,lo* ,c>ron1 pre-,cambrian rocks (1 i4 #aae1 #aag ,lo* ,lomond1 dykes at1 ii4 #ahj ,lo* ,tay ,lime/one1 i4 #abb1 #abd1 #abe ,lomas1 ,mr4 ,j41 ii4 #aia1 #cbb ,longulites1 ii4 #ace ,lonsdale1 ,w41 i4 #beg ,longmyndian rocks1 i4 #aaa1 #abi1 #acb ,lorne1 volcanic rocks (1 i4 #ajb1 #bga1 #bha1 #cda ,l\gh ,mask1 ,silurian volcanic rocks (1 i4 #bea ---- ,nafooey1 ,silurian volcanic rocks (1 i4 #bea ---- ,neagh1 subsid5ce ( site (1 ii4 #bja1 #bje2 hi/ory (1 #ddh ,ludl[ gr\p1 i4 #age ,lycopods1 fossil1 i4 #agd ,ma>e1 volcanic1 i4 #eh2 ii4 #bhg1 #bhh1 #bif ,maccono*ie1 ,mr4 ,a41 ii4 #eh ,maccullo*1 ,john1 i4 #ie1 #bfi1 #bgj2 ii4 #bb1 #aaa1 #aac1 #abc1 #adj1 #aed1 #aef1 #aei1 #agb1 #agd1 #age1 #bac1 #bag1 #bca1 #bcg1 #bdd1 #bea1 #bhj1 #bic1 #cjd-cjg1 #caj1 #cad1 #cae1 #cbg1 #cdi1 #cfd1 #cga1 #djc1 #djf1 #djh1 #dji1 #dah ,macknight1 ,dr41 i4 #bfh1 #cag ,macl>51 ,*>les1 i4 #bfi1 #cag1 #cbe1 #cfc1 #cgb1 #cgc1 #dea1 #dfb2 ii4 #fg ,m',h5ry1 ,mr4 ,a41 i4 #cb1 #bdj1 #bdb1 #bdd1 #cad1 #cdg2 ii4 #bja1 #bjd1 #bgb1 #bic1 #dbf1 #dbg1 #dbh1 #dbi ,m',mahon1 ,g5]al1 i4 #bfj2 ii4 #ce1 #cf ,magma1 volcanic1 explosive en]gy (1 i4 #ac2 gases & vap\rs dissolv$ 91 #ac1 #gb1 #ig1 #ii2 diff]5tiation (1 #bb1 #hd1 #ia2 solv5t action (1 #hb1 #hd1 #he1 #ii2 ii4 #cib1 #dae1 #dbb1 #dcc2 het]og5eity (1 i4 #he1 #ij1 #ia2 ii4 #cdd1 #cfj1 #dgf2 metamorphic action (1 i4 #id2 alt]ation (1 by incorporation ( =eign mat]ial1 #if2 ii4 #chf1 #cij1 #cib2 conditions = ! injection (1 i4 #ig1 #ii ,magnesian ,lime/one1 ii4 #ed ,malv]n1 pre-,cambrian volcanic rocks (1 i4 #acc2 ,cambrian volcanic rocks (1 #afi ,man1 ,isle (1 ,c>bonif]\s volcanic rocks (1 ii4 #bb ,manod1 i4 #ahd ,m>l ,slate1 ii4 #ed ,m>l1 volcanic1 i4 #dbc1 #dcf1 #ddj1 #ddd1 #dff ,m>r1 ,mr4 ,j4 ,e41 i4 #bbg1 #bbh1 #bcj1 #bca1 #bcb1 #bcf1 #bcg1 #bch1 #bij2 ii4 #ahi ,matlock ,ba?1 ii4 #ac1 #bb ,m$it]ranean1 e>?quakes & volcanoes (1 i4 #a ,melaphyre1 i4 #aca ,mello1 ,mr4 ,j4 ,m41 ii4 #bb ,melrose1 rocks ne>1 i4 #cig1 #cih1 #djj1 #dbe ,melt+ ( rocks by igne\s intrusions1 i4 #hb1 #hd1 #he1 #if1 #ii2 ii4 #afc1 #cib1 #dae1 #dbb1 #dcc ,m5ai ,/rait1 i4 #aei ,m5evian gr\p1 i4 #aad ,m]se1 volcanic plateau ( !1 i4 #cge ,metamorphism ( tuffs1 i4 #aeg2 ( lavas 7see "u ,lavas7 ---- by lavas1 i4 #bg2 by sills & bosses1 #hg1 #id1 #ie1 #baf1 #bcf1 #cca1 #cch1 #dca2 ii4 #g1 #bb1 #cf1 #aca1 #adh1 #afc1 #bii1 #cjj1 #caj1 #ccg1 #cci1 #cdj1 #cdg1 #cee1 #cef1 #ceg1 #ceh1 #cfb1 #cgh1 #chc1 #chf1 #cig1 #cii1 #djj1 #djd1 #dac ---- 9 v5ts1 i4 #fg1 #ga1 #hb1 #ic1 #cii1 #djd2 ii4 #ci1 #gh1 #bib ---- ar\nd v5ts1 i4 #gb1 #cdi1 #cej1 #ceb1 #cii1 #djd1 #dcb2 ii4 #gf1 #bgb1 #bgc1 #bgf1 #bhj1 #bib ---- regional1 i4 #aba1 #abc2 ii4 #ce ,mica1 eject$ cry/als (1 9 volcanic breccias1 ii4 #di1 #eh1 #gi1 #hj ,mica-porphyrite1 i4 #bgg1 #cch ,mi*el ,lvy1 ,m41 i4 #ah1 #ba1 #df1 #hh2 ii4 #cgc1 #cgd ,microgranite1 i4 #aca1 #bae1 #bce1 #bdi2 ii4 #cfg1 #dcg ,microlites ( igne\s rocks1 i4 #ah1 #ba1 #cc2 ii4 #ace1 #bge ,micropegmatitic /ructure1 i4 #bj1 #dah1 #ddi2 ii4 #e1 #cfh1 #dcg ,microscopic exam9ation ( rocks1 i4 #ah1 #ba ,midl&s1 eruptive rocks ( ,engli%1 ii4 #ajj ,midlo?ian1 ,c>bonif]\s volcanic plateau (1 i4 #cgc1 #che1 #chg2 sills (1 #ddf ,mill]1 ,hugh1 ii4 #bcg ---- ,mr4 ,h41 i4 #ccf ,mills1 ,abraham1 ii4 #aji ,mill/one grit1 i4 #ceh1 #cfj1 #cff ,m9ette1 i4 #bgg1 #bgh1 #bia1 #bic ,m9to ,crags1 i4 #cge1 #cig ,mit*ell1 ,rev4 ,hugh1 i4 #cja ,moel ,siabod1 i4 #age ---- ,wyn1 i4 #age1 #agf1 #ahd1 #ahe ,monckton1 ,mr4 ,h4 ,w41 i4 #ddi2 ii4 #bbd ,montana1 lava-fields (1 ii4 #aae1 #bfg ,montrose1 volcanoes (1 i4 #bii ,moray ,fir?1 bas9 (1 i4 #bga1 #cdc ,morton1 ,mr4 ,g4 ,h41 i4 #ahi ,morv51 basalt-plateau (1 ii4 #bjh ,m\nta9-*a9s1 orig9 (1 i4 #aa1 #ab1 #ih ,m\rne m\nta9s1 granite (1 i4 #ic2 ii4 #abd1 #cff1 #cfg1 #dbj ,muck1 ,isle (1 ii4 #bae ,mud-lava1 ii4 #he ,mud/one1 volcanic1 i4 #dbc1 #dcf1 #ddj1 #ddd1 #dff2 ii4 #hf1 #bbb1 #beh ,mull1 bran*+ amygdales (1 i4 #ag2 p]litic glass f1 #ai2 pale lavas (1 ii4 #ahd1 #bac2 basalt (1 #ahh1 #aib1 #aic2 breccias (1 #aif2 plateau (1 i4 #bd1 ii4 #bjh2 non-volcanic breccias 91 #aif1 #baa2 fl9t gravel 91 #baa2 leaf-b$s (1 #bab2 v5ts 91 #bgd1 #bgh2 gabbro (1 #cee2 acid bosses (1 i4 #bj2 ii4 #cie2 acid sills (1 #dcj2 acid dykes & ve9s (1 #ddc2 enorm\s d5udation (1 #deg1 #dfa ,mur*ison1 ,r4 ,i41 i4 #aac1 #aba1 #abi1 #adb1 #agc1 #age1 #ahi1 #bjd1 #bje1 #bjg1 #bch1 #beg2 ii4 #ef1 #ie ,mynydd-mawr1 i4 #bji1 #baa1 #baf ,my?ology1 influ5ce ( e>?quakes & volcanoes on1 i4 #b ,nant ,francon1 i4 #afa ,naples1 puys (1 i4 #ajj1 #dbi ,napoleonite1 i4 #bb ,neck]1 ,l4 ,a41 ii4 #aab1 #abc1 #aci1 #adj1 #adf ,necks1 volcanic1 i4 #ef2 ( fragm5t>y mat]ials1 #ef2 ( non-volcanic detritus1 #eg1 #bhi1 #cdc1 #dbf2 ( agglom]ate1 #eh2 ii4 #bgf2 int]nal /ratification 91 i4 #fc2 ii4 #hj1 #bid2 ) c5tral lava-plug1 i4 #fd1 #dcj2 ) dykes & ve9s1 #ff1 #dcj2 ii1 #bia2 ( lava-=m mat]ial1 i4 #fg1 #dcj2 ii4 #bga2 p>asitic1 i4 #fi2 connection (1 ) cones1 #gj1 #dce2 ii1 #gj1 #hi1 #bgg1 #bha1 #bij2 metamorphism (1 i4 #fg1 #ga1 #hb1 #ic1 #cii2 ii4 #ci1 #gh2 metamorphism ( rocks ar\nd1 i4 #gb1 #cdi1 #cej1 #ceb1 #cii1 #djd1 #dcb2 ii4 #gf1 #bgb1 #bgc1 #bgd1 #bgf1 #bhj1 #bib2 inw>d dip ( rocks t[>ds1 i4 #gc1 #ceb2 ii4 #hj2 connection (1 ) bosses1 i4 #ic2 ii4 #bgf1 #bhd2 entombm5t & exposure (1 i4 #dcd2 connection ( ) valleys1 #bgb1 #cff1 #cge2 ii4 #fa1 #fe2 relation betwe5 _! size & ! "* ( ! agglom]ate1 #gf2 connection (1 ) %eets ( tuff or lava1 #gj1 #hi1 #bgg1 #bhd ---- ,silurian1 i4 #bae1 #bce2 ,old ,r$ ,s&/one1 #bgg1 #bhh1 #bic1 #caa1 #cah1 #cbc1 #cbh2 ,c>bonif]\s1 #cid1 #cii1 #djj1 #djd1 #djf1 #dbd1 #dfe2 ii4 #ac1 #bh1 #dg2 ,p]mian1 ii4 #fb1 #fg2 ,t]ti>y1 ii4 #bjb1 #bgj1 #bgf ,neptuni/ & ,plutoni/ controv]sy1 i4 #cfc2 ii4 #fg1 #ie1 #aaj1 #aab ,new ,mexico1 necks 91 i4 #fh ,newry granite1 i4 #bij ,ni*olson1 ,pr(4 ,alleyne1 i4 #bbh1 #bbi ,nicol1 ,james1 i4 #caa1 #cfi ---- ,w41 ii4 #bch ,nigr9e1 ii4 #gi ,ni?sdale1 ,p]mian volcanic rocks (1 ii4 #eh1 #fj1 #fb1 #fe ,nodul> /ructure ( lavas1 i4 #bj1 #afb1 #bjd1 #bjf1 #bjg1 #baa1 #bcb1 #bdg1 #bee1 #bgd1 #cdf ,nolan1 ,mr4 ,j41 i4 #bdj1 #bea1 #cae2 ii4 #dbc1 #dbd1 #dbe ,non-volcanic debris1 among volcanic rocks1 i4 #ca1 #eg1 #bhi1 #cac1 #cde1 #cha1 #cii1 #djb1 #dbb1 #dbf1 #dcg2 ii4 #ah1 #bg1 #bh1 #eh1 #fd1 #gf1 #gh1 #ii1 #aie1 #aif1 #bha1 #dbc2 indicates comp>atively feeble eruptions1 i4 #eg1 #bhi1 #cde1 #dbf1 #dch2 ii4 #bic2 po9ts to e>lie/ eruptions ( a v5t1 ii4 #gf ,nord5skjld1 ,mr4 ,o41 i4 #abj ,nor? ,b]wick ,law1 i4 #cga1 #cgc1 #djc ,nor?1 ,mr4 ,b>k]1 ii4 #bdd ,norway1 eruptive rocks (1 i4 #bh ,nuneaton1 i4 #aga ,obsidian1 i4 #ah1 #ai2 ii4 #cgj ,o*il ,hills1 i4 #bgd1 #bgf1 #bgg1 #bgi1 #bha1 #bhf1 #bhg1 #bhh1 #bic1 #cjc1 #cjh1 #caa ,oil-%ales ( ! ,lo?ians1 i4 #cfa1 #cfb1 #dfb ,o',kelly1 ,j41 i4 #cdi2 ii4 #di ,oldham1 ,t41 ii4 #bii ,old ,r$ ,s&/one1 l9es ( v5ts 91 i4 #fi2 granite protrusions (1 #bcf1 #bgb1 #bgg1 #bij1 #ccg2 ( ,c\nty ,wat]=d1 #bea2 di/ribution 9 ,brita91 #beg2 an exceptional /ratigraphical type1 #beh2 conditions ( its deposit1 #bei1 #bfc1 #big2 orig9al sc5]y (1 #bfe2 vegetation (1 #bfe2 isolation ( ! wat]-bas9s (1 %[n by fossil evid5ce1 #bfe2 classification (1 #bfj2 hi/ory ( ! inve/igation (1 #bfh2 volcanic c5tres 91 #bga2 nature ( volcanic products 91 #bgc2 /ructure ( lavas & tuffs (1 #bha2 volcanoes (1 #bei1 #bfc1 #bid1 #cjc1 #cbc1 #cbe1 #ccg1 #cda1 #cdc1 #cdf1 #cdh1 #ceb2 subdivisions (1 #big2 ?icke/ conglom]ates (1 #cja2 composition ( conglom]ates (1 #cjb1 #cae1 #cda2 uncon=mabilities 91 #bfg1 #cbh1 #ccc2 ,upp] division (1 #cdh1 #cge1 #chc2 ii4 #db ,ol5ellus-zone1 i4 #aab1 #acj1 #acb1 #adj1 #add ,ol5us-zone1 i4 #add ,oliv9e1 i4 #aed1 #dah1 #dbj2 ii4 #eh1 #ace ,omagh1 i4 #cae ,ophitic /ructure1 i4 #ba1 #dag2 ii4 #acf1 #ahd1 #bgd ---- type ( dol]ite1 i4 #dah1 #dba ,oregon1 crat] lake 91 i4 #eh ,orkney ,isles1 i4 #bga1 #cdd1 #cej2 ii4 #aba ,or?oclase1 eject$ cry/als (1 ii4 #gi ,or?ophyre1 i4 #bgc1 #bgf1 #bgg1 #cjh ,osann1 ,a41 ii4 #aia ,oy5haus51 ,c4 von1 ii4 #aab1 #bhj1 #ccc1 #cdj1 #cfg1 #cgb1 #cha ,palopicrite1 i4 #bfa ,palozoic sy/ems1 i4 #aci2 volcanic rocks resemble mod]n1 i4 #cj ,palagonite1 i4 #cc1 #fa1 #aea1 #ahj1 #bdf1 #dbb1 #dbc2 ii4 #dd1 #df1 #eg1 #bbc ,p>adoxides-zone1 i4 #add ,p>amorphism1 i4 #bdi ,pea*1 ,mr4 ,b4 ,n41 i4 #aad1 #abh1 #adg1 #afh1 #aia1 #aib1 #aie1 #aif1 #aig1 #aih1 #aii1 #bjj1 #baf1 #bdj1 #bgg-bid1 #cjg1 #cjh1 #cbi1 #cca1 #cdd1 #cde1 #cfi1 #cge1 #dbe1 #dbf1 #dgf2 ii4 #acc1 #ade ,pebidian1 i4 #ade ,pegmatite1 i4 #bj1 #aai1 #abg1 #dah1 #ddi2 ii4 #e1 #cfh1 #dcg ,pembroke%ire1 volcanic rocks (1 i4 #ade1 #aei1 #bje ,p5ma5-mawr1 i4 #bji1 #bae ,p5nant1 ,t41 ii4 #aji ,p5n9e *a91 ii4 #h ,p5tl& ,hills1 volcanic s]ies ( !1 i4 #ajb1 #bfi1 #bgc1 #bgf1 #bgi1 #bha1 #bhe1 #bhg1 #bhi1 #bia1 #caa1 #cag ,p]lite1 i4 #acj ,p]litic /ructure1 i4 #ai1 #aif1 #aii1 #bjf1 #baa1 #baf1 #bcb1 #bgd ,p]mian sy/em1 geographical conditions accompany+ ! deposition (1 ii4 #ec1 #ig2 subdivisions (1 9 ,s4 ,w4 ,engl&1 #id2 volcanic ph5om5a (1 i4 #df2 ii4 #ee2 lavas & tuffs (1 #eg1 #eh2 v5ts (1 #fb1 #fg1 #gj1 #if2 sills (1 #ia1 #ajj ,p]mo-c>bonif]\s /rata1 ii4 #ed ,pet]s51 ,dr41 i4 #bge1 #ccf ,phillips1 ,j41 i4 #acc1 #agj1 #bje1 #bch2 ii4 #c ---- ,j4 ,a41 i4 #bfj1 #bfa ---- ,w41 i4 #aga2 ii4 #ie ,phonolite1 i4 #chj 7analysis72 ii4 #cge ,phyllite1 i4 #afb1 #bbb ,picrite1 i4 #cgg1 #dag1 #dbj1 #ddh1 #dej2 ii4 #eg ---- type1 i4 #dah ,pill[-/ructure 9 lavas1 i4 #bf1 #ahd1 #aic1 #bja1 #bdj1 #bdd1 #beb2 ii4 #ahi1 #bei ,pit*/one1 i4 #ah1 #ai1 #acj2 ii4 #acd1 #agd1 #bjd1 #bch1 #bdb1 #bdf1 #cgj1 #dcg1 #ddd ,plagioclase1 eject$ cry/als (1 ii4 #gi ,plants fossil1 9 tuffs1 i4 #cib2 ii4 #aac1 #aih1 #bab1 #bbb ,platania1 ,g41 i4 #bf ,plateau-type ( volcanoes1 i4 #db1 #ajj1 #cjh1 #cda1 #cfd ,plateaux1 ,c>bonif]\s1 ( ,scotl&1 i4 #cfd2 di/ribution (1 #cfg2 composition (1 #cgg2 /ructure (1 #chc2 lavas & tuffs (1 #chc2 v5ts (1 #cid2 dykes & sills (1 #djf2 close ( eruption (1 #daj2 ,t]ti>y1 ii4 #aha2 =mation ( mod]n ,icel&ic1 #bfe ,play]1 ,mr4 ,j4 ,h41 analyses by1 i4 #cgg1 #cha2 ii4 #ach1 #ccj ,playfair1 ,john1 i4 #cfc2 ii4 #aaj ,pl9?ite1 ii4 #aig ,plioc5e 7suppos$7 ( ,l\gh ,neagh1 ii4 #ddi ,plutonic op]ations ( volcanoes1 i4 #gg2 granite1 #hh ,plutoni/s & ,neptuni/s1 i4 #cfc2 ii4 #fg1 #ie1 #aaj1 #aab ,pom]oy1 volcanic s]ies ne>1 i4 #cae ,porphyrite1 i4 #aij1 #aic1 #bjg1 #bbi1 #bdj1 #beb1 #bgc1 #bgd1 #cgg1 #cgi ,porphyritic /ructure1 i4 #ai1 #bgd2 ii4 #abh ,portlock1 ,j4 ,e41 ii4 #aaj1 #aaa1 #aac1 #aii1 #bja1 #bii1 #cfd ,portra9e1 conglom]ates at1 i4 #bdd ,portru%1 %ells 9 suppos$ basalt at1 ii4 #aaj1 #bii ,pot/one1 i4 #abe ,pre-,cambrian rocks1 i4 #aaa1 #aba1 #abf ,pressure1 exp]im5tal pro( ( effects (1 i4 #bd ,pre/wi*1 ,sir ,j41 ii4 #ajc ,propylites1 ii4 #ahe1 #chh ,prot]obase1 i4 #bdg ,pt]ygotus1 i4 #bfe ,pumice 9 tuffs1 i4 #bdd1 #dbb2 ii4 #ag1 #bg1 #bh1 #cb1 #dd1 #df1 #bhf1 #bhh2 9 volcanic necks1 i4 #fj1 #ahj2 ii4 #ag1 #ci1 #aie ,pumice\s /ructure1 i4 #ae1 #cc1 #cd1 #fj ,puys1 z a type ( volcano1 i4 #aj1 #dd1 #ajj1 #dad2 probable subrial nature ( "s1 #dcb2 ,c>bonif]\s1 #cjh1 #cfd1 #dad1 #dbd1 #dfc2 ii4 #ac1 #bh1 #cd1 #dg2 ,p]mian1 ii4 #fb2 ,t]ti>y1 #bga1 #bgf ,puy de ,*op9e1 i4 #cb2 ii4 #cgd ---- ,dme1 ii4 #cgc ---- ,mont*>1 i4 #cb ---- ,p>i\1 i4 #ff1 #gj2 ii4 #ca1 #bha ,pyrocla/ic detritus1 i4 #ca1 #eh1 #fa ,pyrom]ide1 i4 #baa ,pyrope1 ii4 #eh1 #gi ,pyrox5e1 ii4 #ace ,qu>tz-porphyry1 i4 #ai1 #aef1 #aei1 #afj1 #afa1 #afe1 #bgg1 #bia1 #cad2 ii4 #if1 #cfi1 #dbj1 #dbc1 #dcj1 #dca ,qu>tz-tra*yte1 ii4 #cga ,qu>tzite1 i4 #aab1 #agj ,raasay1 basalt (1 ii4 #aib2 neck-l breccias 91 #bic2 acid sill (1 #dcj ,raddl+ or r$-/a9+ ( rocks1 i4 #bej1 #bfa ,radiol>ian *]ts1 i4 #abc1 #afg1 #afi1 #agc1 #agd1 #ahd1 #aif1 #bja1 #bdd ,ra9-pitt+s 9 /rata1 i4 #cdb ,rais91 ,miss1 i4 #afa1 #afc1 #afd1 #afe1 #baj ,ramsay1 ,a4 ,c41 i4 #abf1 #adb1 #adc1 #add1 #ade1 #aeh1 #aei1 #afh1 #age1 #agf1 #agg1 #agh1 #agi1 #ahj1 #ahb1 #ahc1 #bjd1 #bje1 #bjh1 #baj1 #bab1 #bad1 #bbc1 #bcg1 #cfd ,ra?o type ( dol]ite1 i4 #dah1 #dba ,r$ ,head1 section at1 i4 #cjj ,r$ ,hills1 ,skye1 sc5]y (1 i4 #aje2 ii4 #cgi ,re$1 ,mr4 ,c[p]1 i4 #bje ,reid1 ,mr4 ,clem5t1 ii4 #ddi1 #dej ,r5>d1 ,pr(4 ,a41 i4 #adh1 #adi ,r5frew%ire1 ,c>bonif]\s volcanic rocks (1 i4 #cfh1 #che1 #cig1 #djj1 #djd1 #djh1 #daf1 #dcj1 #ddg ,rey]1 ,pr(4 ,e41 ii4 #dgd ,reynolds1 ,mr4 ,s4 ,h41 i4 #agg1 #agi1 #bef ,rhobel ,fawr1 i4 #agg1 #agh1 #ahf ,rhyolite1 i4 #ai1 #bb1 #bd1 #aca1 #afa1 #afe1 #afg1 #afh1 #agh1 #bjd1 #baj1 #bca1 #bcb1 #bee1 #bgf1 #bgh2 ii4 #ahe1 #bje1 #cga1 #dbd1 #dcg ,rhyolitic conglom]ate1 ii4 #aie1 #bjf1 #dbi ,ri*>dson1 ,rev4 ,w41 ii4 #aaj ,ri*?(51 ,f4 von1 i4 #bh2 ii4 #aae1 #aaf ,riv]s made to %ift _! *annels by volcanic eruptions1 i4 #db1 #di2 ( ! ,t]ti>y volcanic p]iod1 ii4 #bag1 #bbh1 #bca1 #bcd1 #def ,rocks1 olde/ kn[n1 i4 #aaj ,roscommon1 volcanic rocks (1 i4 #caf ,ros5bus*1 ,pr(4 ,h41 ii4 #acf1 #acg ,ross1 ,mr4 ,alex&]1 ii4 #djf1 #dji ,ro?lieg5de1 ii4 #ie ,roxburgh%ire1 ,c>bonif]\s v5ts (1 i4 #ee1 #djc1 #djd ,rub]s ,law1 i4 #cge1 #chj1 #djd ,rum1 i4 #aab2 basalt-plateau (1 ii4 #bae2 gabbros (1 #ccb1 #cdi2 acid bosses (1 #djc2 acid sills (1 #dca2 pit*/one (1 #dde ,rutley1 ,mr4 ,f41 i4 #aca1 #acc1 #agj1 #bjg1 #baj1 #bbg1 #bca1 #bcb1 #bch1 #bfj2 ii4 #bc1 #ce ,sahlite f\nd 9 volcanic v5ts1 i4 #fb ,sal9e ,hill1 volcanic v5ts (1 i4 #dcc1 #dce1 #ddj ,s&ay1 basalts (1 ii4 #bae2 conglom]ates (1 #bbf ,s&/one alt]$ into qu>tzite1 i4 #gb1 #cdi1 #cej1 #djd1 #dcb1 #dea2 ii4 #gf1 #afd2 ve9+s (1 9 lava1 i4 #bhc1 #cjj1 #cjc1 #cbj1 #cbg1 #ccc1 #ccg2 ii4 #ei1 #ih ,s&wi* ,isl&s1 lava-cones (1 i4 #aj ,sanid9e eject$ f volcanic v5ts1 ii4 #eh1 #gi ,sanquh>1 ,silurian volcanic rocks at1 i4 #aib1 #aie1 #aii2 ,p]mian volcanic rocks at1 ii4 #fb ,santor91 ii4 #acd ,saponite1 ii4 #gi ,sc5]y1 orig9 (1 i4 #h1 #ajj ,s*al/e91 i4 #bfb2 ii4 #cf ,s*i/s1 primeval1 i4 #aaj1 #aad1 #aah1 #aai2 produc$ by de=mation ( igne\s rocks1 #ge1 #aad1 #aah1 #aai1 #aba1 #afb1 #bdj1 #bdi1 #beb1 #bfa ,s*midt1 ,dr4 ,c4 ,w41 ii4 #bff ,scoriace\s /ructure1 i4 #ae1 #af1 #bhb1 #cbg1 #cci ,scorpions1 fossil1 i4 #agd1 #cef1 #dff ,scotl&1 l9es ( fault 91 i4 #aa2 ,vesuvian cones (1 #db2 plateaux (1 #dc2 puys (1 #df2 subm>9e lavas (1 #dh2 ,c>bonif]\s v5ts (1 #ee2 volcanic sc5]y (1 #ajd2 pre-,cambrian rocks (1 #aaa2 ,cambrian rocks (1 #aab2 ,lewisian gneiss (1 #aad2 ,dalradian rocks (1 #aba2 ,ar5ig rocks (1 #abc1 #aia2 ,old ,r$ ,s&/one (1 #bff1 #bgc1 #bha1 #bia2 ,c>bonif]\s geography (1 #cef2 ,c>bonif]\s volcanoes (1 #cei2 ,c>bonif]\s plateaux (1 #cfg2 ,c>bonif]\s puys (1 #dad2 ,p]mian volcanoes (1 ii4 #ee2 ,t]ti>y dykes (1 #abb2 ,t]ti>y basalt-plateaux (1 #bjh1 #bgd1 #cjd2 ,t]ti>y gabbros (1 #cbg2 ,t]ti>y acid rocks (1 #cgi ,scrope1 ,g4 ,p41 i4 #bg1 #hb1 #de1 #aaf2 ii4 #cgc1 #cgd1 #cha ,s$gwick1 ,a41 i4 #adb1 #aff1 #age1 #bah1 #bbg1 #beg2 ii4 #a1 #b1 #c1 #e1 #aac1 #aci1 #aec1 #aeg ,segregation 7see ,diff]5tiation7 ,segregation-ve9s1 i4 #hd1 #ib2 ii4 #ff1 #acj1 #cjj1 #cjc ,selwyn1 ,mr4 ,a4 ,c4 ,r41 i4 #adc1 #age1 #bjh1 #bba ,semi-opal1 ii4 #gi ,sepul*re ,m\nta91 i4 #gi ,s]p5t9e1 i4 #aie1 #bic ,%ale1 alt]ation (1 i4 #gb1 #dea2 ii4 #afd ,%ap1 granite (1 i4 #bcf1 #bch1 #bga1 #bij ,%eets1 intrusive 7see ,sills7 ,%elve1 i4 #agf1 #aij ,%etl&1 i4 #bga1 #bhi1 #bib1 #bic1 #cde ,%iant ,isles1 ii4 #cjg ,%9eton ,%ales1 i4 #add ,%ore-l9es1 traces ( anci5t1 i4 #bie1 #cje ,%rop%ire1 anci5t volcanic rocks (1 i4 #abi1 #ahi2 late/ eruptive rocks (1 ii4 #aja ,sicily1 i4 #bf ,sidlaw ,hills1 i4 #bhf1 #bid1 #cjc ,sills1 vitre\s m>g9s (1 i4 #ah2 tectonic relations (1 #gg1 #hc1 #dea2 orig9 ( "n1 #hc2 diff]5tiation 7segregation7 91 #ha1 #dej2 ii4 #dgf2 ord9>y /ratigraphical position (1 i4 #he2 consid]$ z p>ts ( incomplet$ volcanoes1 #hf2 metamorphism by1 #hg1 #id1 #dea2 ii4 #bii1 #cjc1 #caj2 conditions = injection (1 i4 #ig1 #ih1 #ii1 #deh2 column> /ructure (1 ii4 #ahg1 #bia1 #cja1 #cjf1 #cjh1 #cai2 amygdaloidal /ructure 91 #bii1 #cab2 b&+ (1 #cji2 split by lat] sills1 #caj1 #caf2 extreme subdivision (1 #caa2 slaggy surface 9 "s1 #cab2 give (f ve9s1 #cac2 d\ble & multiple1 #cah1 #dcd2 connection ) v5ts1 #cbb ---- pre-,cambrian1 i4 #aah1 #abd2 ,cambrian1 #aee1 #agj1 #aga2 ,silurian1 #ahg1 #aie1 #bjf1 #baf1 #bcg1 #bdi2 ,devonian1 #bfa2 ,old ,r$ ,s&/one1 #bgg1 #bia1 #cba1 #cce1 #cdc1 #cde2 ,c>bonif]\s1 #djh1 #ddf1 #dgb2 ii4 #b1 #ba1 #cj1 #dh2 ,p]mian1 #fd1 #ff2 ( ,midl&s1 #ajb1 #ajc2 ,t]ti>y1 7#a7 ,basic1 #bih2 7#b7 ,acid1 #cff1 #dcj ,silurian sy/em1 i4 #agc2 vegetation (1 #agd2 geography (1 #bfc2 volcanoes (1 #age2 classification (1 #age2 two volcanic s]ies (1 #agg ---- volcanoes 9 ,%rop%ire1 i4 #ahi2 9 ,scotl&1 #aia2 at ,buil?1 #bjc2 9 ,pembroke%ire1 #bje2 9 ,ca]n>von%ire1 #bjg2 9 ! ,b]wyn ,hills1 #bah2 9 ,anglesey1 #bai2 9 ! ,lake ,di/rict1 #bbg2 9 ,gl\ce/]%ire1 #bch2 9 ,irel&1 #bci1 #bed ,skae1 ,h4 ,m41 i4 #bid1 #bii1 #cjf1 #cge2 ii4 #eg ,skiddaw1 i4 #bbh2 granite (1 #bcf ---- ,slate1 i4 #bbi ,skom] ,isl&1 i4 #bjg ,skye1 sph]ulitic dykes & sills (1 i4 #bj2 ophitic /ructure f1 #bj2 basalt-t]races (1 #bd2 metamorphism by granophyre (1 #ie1 #if2 volcanic sc5]y (1 #ajc1 #aje2 dykes (1 ii4 #abc1 #abd1 #abi1 #aci1 #adj1 #adf1 #aej1 #aeb1 #aed1 #afj1 #afb1 #afd1 #afe1 #agc1 #bfi2 b$d$ basalts (1 #aib1 #bdi1 #bfi2 tuffs (1 #bea2 connection ( dykes & sup]ficial lavas 91 #bfi2 v5ts 91 #bhj2 sills (1 #cjd2 gabbro bosses (1 i4 #aaf2 ii4 #ccd2 acid bosses (1 #cgi2 acid sills (1 #dca2 acid dykes (1 #dcg2 pit*/one ve9s (1 #dde2 subsid5ce (1 #ddg ,slaggy /ructure1 i4 #af1 #cc1 #ei1 #bhb1 #cbg1 #cci2 ii4 #ih1 #ahg ,slane1 volcanic rocks ne>1 i4 #bdd ,slate-tuffs1 i4 #ahj1 #bac1 #bcd ,slemi% a volcanic neck1 ii4 #bga ,slieve ,foye1 ii4 #dba ---- ,gallion1 ii4 #bjj ---- ,gullion1 ii4 #dbb ,small ,isles1 basalt-plateau (1 ii4 #bae2 v5ts (1 #bhh2 sills (1 #cah2 acid bosses (1 #djc2 acid sills (1 #dca ,small1 ,mr4 ,e4 ,w41 i4 #bjg ,sm>agdite f\nd 9 volcanic v5ts1 i4 #fb ,sn[don1 volcanic rocks (1 i4 #bj1 #db1 #dg1 #ajb1 #age1 #bjh1 #bji1 #baj1 #baa1 #bab1 #bac1 #bah1 #bbf ,soda-felsites1 i4 #ahc1 #aif1 #bdg ,solfat>ic action1 i4 #ga2 ii4 #ahe1 #bje1 #chh ,sollas1 ,pr(41 i4 #if2 ii4 #age1 #bic1 #dae1 #dba1 #dbb ,solway1 ,c>bonif]\s volcanic plateau (1 i4 #cge1 #che1 #dac ,som]set1 volcanic rocks (1 ii4 #cb ,somma1 d5udation (1 i4 #c1 #ajj ,sph]oidal /ructure ( dol]ite1 i4 #def ,sph]ulitic /ructure1 i4 #ai1 #bj1 #ie1 #abj1 #acj1 #aee1 #afb1 #ahd1 #baa1 #bcb1 #bce1 #cdf2 ii4 #cfi1 #cha1 #cib1 #dcb1 #dce1 #dcg1 #dda1 #ddf ,spilosite1 i4 #bfb ,spr+s1 m9]al1 connect$ ) volcanic action1 i4 #cij1 #dde ,/4 ,abb's ,head1 i4 #cch ,/affa1 i4 #be2 fir/ notice (1 ii4 #aji2 column> basalts (1 #ahf1 #ahh1 #baj2 basalt conglom]ate (1 #aie ,/af=d%ire1 late/ eruptive rocks (1 ii4 #aja1 #ajc ,/4 ,&rews1 old volcanoes ne>1 ii4 #ga1 #gc1 #hg ,/4 ,david's1 ,cambrian volcanic rocks (1 i4 #ade ---- ,head1 i4 #bje ,/eam 9 volcanic action1 i4 #ac1 #ae1 #af1 #ga ,/e*]1 ,dr41 i4 #dba1 #dea2 ii4 #afe ,/4 ,kilda1 dykes (1 ii4 #agc1 #daf2 gabbro (1 #ceh2 g5]al acc\nt ( geology (1 #dje2 granophyre (1 #djh ,/ocks1 or bosses1 i4 #gh1 #hh ,/rahan1 ,mr4 ,a41 i4 #aga2 ii4 #aj1 #ab1 #bc1 #bh1 #cb ,/ra?aird1 ii4 #abc1 #adj1 #afd1 #bfi ,/ra?bogie1 i4 #cdd2 ii4 #aba ,/ra?more1 i4 #cjd ,/romboli1 i4 #d ,sublimations1 traces ( anci5t1 i4 #dde ,subm>9e eruptions1 i4 #dh ,sub-ophitic /ructure1 i4 #dag ,subsid5ce & volcanic action1 i4 #bie1 #big1 #ddd1 #dfc2 ii4 #db1 #bje1 #ddg1 #dgj ,subt]ranean igne\s injections1 i4 #gg 7see ,bosses1 ,dykes1 ,sills7 ,suess1 ,pr(4 ,e41 ii4 #dgd ,sun-cracks1 i4 #cdb ,sw$51 ,ar*an volcanic rocks (1 i4 #abj ,sy5ite1 ii4 #cff ,symes1 ,mr4 ,r4 ,g41 i4 #caa1 #cdc1 #cfi2 ii4 #bja1 #dbh ,tate1 ,g41 ii4 #c1 #aac ---- ,r41 ii4 #bjd ,tatlock1 ,mr4 ,r4 ,r41 i4 #bgc1 #bgh ,tawney1 ,e4 ,b41 i4 #aeg ,teall1 ,mr4 ,j4 ,j4 ,h41 i4 #ij1 #aad1 #aaf1 #aag1 #aah1 #aai1 #abj1 #aef1 #aib1 #aid1 #bjj1 #bjg1 #baj1 #bge1 #bgg1 #bij1 #caa1 #ccf1 #cch1 #cdf1 #djg1 #ddi2 ii4 #b1 #c1 #e1 #g1 #aa1 #cb1 #dd1 #aac1 #aca1 #acd1 #ace1 #acg1 #ach1 #adj1 #add1 #adi1 #bib1 #bic1 #cbi1 #cfg1 #cfh1 #cfi ,teesdale1 i4 #bbh ,t]mi]1 ,m4 ,p41 ii4 #cge ,t]re/rial volcanic eruptions1 i4 #ej ,t]ti>y ,volcanic ,s]ies1 ii4 #aha ,suba]ial "* ( eruptions1 ii4 #ajc1 #aih ,sc5]y (1 ii4 #bee1 #bef1 #cdi1 #cia1 #dje1 #djh ,! ,plateaux1 ii4 #ahc1 #bdi2 lavas (1 #ahc1 #bah1 #bcf1 #bef2 ?ickness ( individual %eets1 #aib1 #bjf1 #bed1 #beg2 l5ticul> "* ( lavas (1 #aic1 #beg2 greate/ dep? (1 #baj1 #baa1 #bac1 #bfj2 tuffs & clays (1 #aid1 #bjb1 #bjd1 #baa1 #bbb1 #bbe1 #bea1 #beh1 #bgg1 #bhd1 #bhg2 non-volcanic fragm5ts 91 #aif1 #baa1 #bac1 #bai2 lignites (1 #aih1 #bjc1 #bjh1 #bac1 #bea2 gravels & conglom]ates (1 #aih1 #bab1 #bch1 #bef2 coal (1 #bac1 #bea1 #bef1 #bhg2 leaf-b$s (1 #bjd1 #bab1 #bbb1 #bbe1 #bhh2 c>bonace\s nature ( ! upp] p>ts ( int]calat$ s$im5ts 91 #bbc1 #bbf1 #bbg1 #bbi1 #bcb1 #bea1 #bhh2 evid5ce = int]vals betwe5 ! eruptions 91 #bjc1 #bje1 #bjh1 #bba1 #bbh1 #bdj1 #bde1 #bea1 #bed1 #bhh2 no evid5ce ( great c5tral v5ts 91 #bjh1 #bad1 #bee1 #beh1 #bfj1 #bfg2 fault$ condition (1 #bjj1 #bjh1 #bji1 #deb2 subsid5ces (1 #bje1 #bjh1 #bji1 #bad1 #ddg2 anci5t riv] *annels (1 #bag1 #bbh1 #bca1 #bcd1 #def2 volcanic cones (1 #bjb1 #bah1 #bcj1 #bgg1 #bha1 #bhe2 p>allel$ by ! mod]n ,icel&ic eruptions1 #bfj2 v5ts (1 #bjb1 #bah1 #bcj1 #bgj1 #bgf ,! ,basic sills1 ii4 #bih1 #cjd ,! ,gabbro bosses1 ii4 #cbg1 #cdi1 #cee1 #ceh2 hi/ory ( ! gabbro intrusions1 #cei ,! ,acid rocks1 ii4 #cfd2 petrography (1 #cff2 hi/ory ( _! inve/igation1 #cga2 analogies ) tra*ytes ( ,c5tral ,france1 #cgc2 intrud$ at base ( ! gabbros or ( ! b$d$ basalts1 #ccg1 #cec1 #ceg1 #dca1 #dcb1 #ddd2 bosses ( ,skye1 #cgh2 ( ,mull1 #cie2 ( ,small ,isles1 #dje2 ( ,/4 ,kilda1 #dje2 ( ,arran1 #dah2 ( ,c>l+=d1 #dbj2 ( ,slieve ,foye1 & ,b>navave1 #dba2 ( ,slieve ,gullion1 #dbb2 ( ,antrim1 #dbf2 acid sills1 #dcj2 acid dykes & ve9s1 #dcg ,metamorphism ( ! basalts1 ii4 #bgb1 #bgf1 #ccg1 #cci1 #cdj1 #cdg1 #cee1 #cef1 #ceg1 #ceh1 #cfb1 #cgh1 #chc1 #chf1 #cig1 #cii1 #djj1 #djd1 #dac ,texture1 v>ieties (1 9 igne\s rocks1 i4 #gh1 #ddi2 ii4 #e1 #bii1 #cfj ,?oleiites1 ii4 #acg1 #aeh ,?oleiite type ( basalt1 i4 #dai1 #dba ,?ornhill1 volcanic rocks (1 ii4 #fj ,?orodds51 ,?41 ii4 #bfa1 #bfb1 #bfc1 #bfd1 #bfe1 #bff1 #bgh ,?ru/-planes1 i4 #bbi ,"t 9 geological hi/ory1 ii4 #ajg1 #dfa1 #dfe ,timm9s1 ,j4 ,h41 i4 #acc ,t9to1 i4 #bgh1 #bhh1 #cbi ,titt]/one ,clee ,hill1 ii4 #aja ,toad/ones ( ,d]by%ire1 i4 #cei2 ii4 #h ,topley1 ,w41 i4 #adg2 ii4 #c1 #e1 #g ,torridonian rocks1 i4 #aaa1 #aab1 #aac1 #abj2 ii4 #cej ,tortwor?1 volcanic rocks at1 i4 #bch ,t\rmakeady1 volcanic rocks ( ,bala age at1 i4 #bea ,t[nson1 ,r41 i4 #cfc ,tra*yte1 i4 #ahc1 #bcj1 #bdf1 #bgc1 #bgf 7analysis71 #cgi 7analysis71 #chf1 #djc1 #djg1 #dba2 ii4 #cf1 #dg1 #if1 #ach1 #aeb1 #ahd1 #bcf ,traill1 ,mr4 ,w41 ii4 #age1 #dba1 #dbb ,trapra9 ,law1 i4 #cgb1 #chj1 #djc1 #dje ,traquair1 ,dr4 ,r4 ,h41 i4 #bff ,tremadoc gr\p1 i4 #add1 #agg ,trevelyan1 ,w4 ,c41 ii4 #c ,triassic eruptive rocks1 i4 #bi2 geography1 ii4 #ajh ,tri*ites1 i4 #ai2 ii4 #acf ,troctolite1 ii4 #ccb ,tuffs1 i4 #ca2 association (1 #cc2 composition (1 #cd2 alt]nations (1 #cd1 #fa2 bl5d+ (1 ) non-volcanic s$im5t1 #ce1 #dcg2 fossilif]\s1 #cf2 )\t lava1 #cf2 necks (1 #eh2 relation (1 to lavas1 #fa2 metamorphism (1 ii4 #bbd ---- pre-,cambrian1 i1 #abe1 #ace2 ,cambrian1 #adg1 #aea1 #aee1 #afc1 #afe1 #afg2 ,silurian1 #agh1 #ahi1 #aij1 #aie1 #bje1 #bji1 #bab1 #bac1 #bbb1 #bbd1 #bbi1 #bcb1 #bda1 #bde1 #bdf1 #bed1 #bee2 ,devonian1 #bfb2 ,old ,r$ ,s&/one1 #bgi1 #bha1 #bhi1 #ccg1 #cci1 #cea2 ,c>bonif]\s1 #cha1 #chd1 #chg1 #cii1 #dbb1 #dbg1 #dbi1 #dcb1 #dcf1 #dff2 ii4 #aa1 #ah1 #bd1 #cf2 ,p]mian1 #eg1 #eh2 ,t]ti>y1 #aid1 #aig1 #bjb1 #bjd1 #baa1 #bbb ,tyrol1 ,triassic eruptive rocks (1 i4 #bi ,tyrone1 ,old ,r$ ,s&/one (1 i4 #cad ,ul/]1 ,old ,r$ ,s&/one volcanic rocks (1 i4 #cad ,ultra-basic rocks1 i4 #ad1 #aah1 #cgg1 #dag ,uncon=mability1 deceptive case (1 i4 #afc ,urgneiss1 i4 #aaj ,uriconian volcanic rocks1 i4 #abi ,us%]1 ,mr4 ,w4 ,a4 ,e41 i4 #bfj1 #bfb2 ii4 #ce1 #ie ,utah1 laccolites (1 i4 #hf2 volcanic regions (1 ii4 #aae1 #bfg ,valleys1 t5d5cy ( v5ts to appe> 91 i4 #bgb1 #cfh1 #cgf2 ii4 #fa1 #fe1 #if ,vap\rs1 action ( volcanic1 i4 #ac1 #ae1 #af1 #ag1 #ca1 #eg1 #gb1 #gh1 #ig1 #ii1 #ahj1 #bhi1 #dbf ,v>iolitic /ructure1 i4 #ba1 #bjf1 #bce ,ve9s1 intrusive1 i4 #ff1 #gg1 #gi1 #ih1 #dbf1 #dbi2 ii4 #caa1 #cac1 #djj1 #daj1 #dcb1 #dcg ,velay1 volcanic rocks (1 i4 #bf1 #bg1 #bi1 #fj2 ii4 #bga1 #cgc1 #cge ,v5ts1 volcanic1 i4 #ec2 gr\nd-plans (1 #ed2 size (1 #ee2 fill$ ) non-volcanic detritus1 #eg2 eject$ cry/als f\nd 91 #fb2 agglom]ates (1 #fb2 ii4 #ac1 #bh1 #dg1 #fa1 #fi1 #bgf1 #bhj1 #bhd1 #bhh1 #bhi2 /ratification 91 i4 #fc2 ii4 #hj2 metamorphism 91 i4 #fg1 #ga2 metamorphism ( rocks ar\nd1 #gb1 #cdi1 #cej1 #ceb1 #cii1 #djd1 #dcb2 ii4 #gf1 #bgb1 #bhj2 connection (1 ) geological /ructure-l9es1 i4 #fh2 occurr5ce (1 9 l9es & 9 gr\ps1 #fi2 d\ble & multiple1 #fi2 possible indications ( l5g? ( activity (1 #gb2 inw>d dip ( /rata ar\nd1 #gc1 #ceb2 ii4 #gf1 #bie2 /ages 9 hi/ory (1 i4 #gd2 t5d5cy (1 to rise 9 l9es ( valley1 #bgb1 #cfh1 #cgf2 ii4 #fa1 #fe1 #if1 #dfh2 crit]ia = ! relative ages (1 #bgj2 connection (1 ) lat] eruptive bosses1 #bhj1 #chd1 #cii1 #djj ---- ,silurian1 i4 #bji1 #bad1 #bcd2 ,old ,r$ ,s&/one1 #bgb1 #bhg1 #bih1 #cje1 #cbc1 #cbh1 #ccg2 ,c>bonif]\s1 #cid1 #cii1 #djj1 #djd1 #djf1 #dbd1 #dfe2 ii4 #ac1 #bh1 #dg2 ,p]mian1 #fa1 #fi2 ,t]ti>y1 #bjb1 #bgj1 #bid1 #djj ,vesicul> /ructure ( lavas1 i4 #ae2 ii4 #ahg ,vesuvius1 d5udation (1 i4 #c2 z an active volcano1 #d2 z a type ( volcano1 #aj1 #ci1 #ec1 #ajj2 ii4 #ajh1 #aae1 #bfa1 #bff ,vic>y1 ,mr4 ,w41 ii4 #ie ,vogesite1 i4 #bgg1 #bic ,volcanello ,isl&1 i4 #gj ,volcanic action1 p]man5t traces (1 i4 #d2 ( pres5t "t elucidates t ( ! pa/1 #e2 subm>9e1 #e2 transi5t effects (1 #h2 *ief factors 91 #aj2 explosive en]gy (1 #ac1 #ii2 uni=mity (1 9 geological "t1 #ac1 ii4 #dgj2 metamorphism by1 i4 #fg1 #ga2 und]gr\nd phases (1 #gg2 pro(s ( gradual quiesc5ce (1 #aee1 #aeg1 #aff2 connect$ ) subsid5ce1 #bie1 #big2 ii4 #bje1 #ddd1 #dfc1 #dgj2 repetition (1 9 ! same region1 i4 #cfh1 #cge1 #cgg2 ii4 #db1 #fi1 #id1 #dfg2 develop$ along cont95tal bord]s1 #dff2 p]si/5ce (1 9 ,brita91 i4 #g2 ii4 #dff2 connection (1 ) l9es ( geological /ructure1 #dfh2 connection (1 ) t]re/rial di/urbance1 #dfi2 gradual decl9e (1 dur+ ,palozoic "t1 #dga2 quiesc5ce (1 dur+ ,mesozoic "t1 #dgb ,volcanic cycles1 i4 #bg1 #ib ---- products1 g5]al *>act]s (1 i4 #ad2 p]si/5t uni=mity (1 #cj1 #df2 ?icke/ mass (1 9 ,brita91 #bbi 7see ,agglom]ate1 ,lava1 ,tuff7 ,volcano1 ,isl& (1 i4 #d1 #bd ,volcanoes1 _! influ5ce on my?ology1 i4 #a1 #b2 d5udation (1 #c2 numb] ( ext9ct1 #d2 anci5t1 ( ,brita91 #f2 influ5ce on sc5]y1 #h1 #ajj1 #ajb2 def9$1 #aj2 types (1 #aj1 #ci2 ii4 #dga2 det]m9ation ( relative dates (1 i4 #df2 _! geographical condition 9 old times1 h[ asc]ta9$1 #dh2 p>asitic1 #fi2 contemporane\s d5udation (1 #gc1 #ajj2 connect$ ) granite1 #hi2 incomplet$1 #hf1 #ic1 #ii ,vom ,ra?1 ,g41 ii4 #dgd ,wacke1 i4 #aeg ,walcott1 ,mr41 i4 #cj ,wales1 pre-,cambrian rocks (1 i4 #abf1 #adb2 e>ly geological "w 91 #adb2 ,cambrian volcanoes (1 #ade1 #aei2 volcanic sc5]y (1 #agf2 ,silurian volcanoes (1 #agf1 #bjb1 #bje1 #bjg1 #bah1 #bai2 ,old ,r$ ,s&/one (1 #beg1 #bei ,wall]1 ,mr4 ,t4 ,h41 i4 #aga1 #bgh ,w>d1 ,j4 ,c41 i4 #bbg1 #bbh1 #bbi1 #bcj1 #bca1 #bcc1 #bcd1 #bce1 #bcf1 #bcg2 ii4 #bc ,w>wick%ire1 ,cambrian rocks (1 i4 #acg1 #aga ,wat]=d1 volcanic region (1 i4 #bdg ,watts1 ,mr4 ,w4 ,w41 i4 #aca1 #acb1 #ace1 #acg1 #ahi1 #aij1 #aia1 #bdc1 #bgf1 #bgh1 #ccf1 #cdg1 #dag1 #dba1 #dbc2 ii4 #dj1 #db1 #dc1 #de1 #eg1 #if1 #ahd1 #bjd1 #bbd1 #bgb1 #dbd1 #dbe ,weav]1 ,t41 i4 #bch ,w5lock gr\p1 i4 #age2 volcanic rocks (1 #eeb ,w]n]ian ,s*ool1 ii4 #aji ,we/ ,lo?ian1 volcanic rocks (1 i4 #dg1 #ee1 #dae1 #dcc1 #dcg ,:9 ,sill ( ,engl&1 i4 #hc1 #he1 #ig1 #ddi2 ii4 #b ,:itehur/1 ,j41 ii4 #i1 #aji ,:ite trap1 i4 #if1 #dbf1 #ddi1 #def2 ii4 #fe1 #hg1 #ajc1 #afe1 #beb ,williams1 ,mr4 ,g4 ,j41 i4 #agi1 #ahe1 #ahf1 #ahh ,williamson1 ,w4 ,c41 i4 #cib ,wilson1 ,mr4 ,j4 ,s4 ,grant1 i4 #adh1 #adi1 #aec1 #bgf1 #cdd1 #cge1 #cgi1 #chj2 ii4 #acg1 #afd ,wilson1 ,mr4 ,a41 ii4 #di ,w9*1 ,n4 ,t41 ii4 #aac1 #adg ,)am1 ,h4 ,t4 ,m41 ii4 #aac1 #bch ,wood1 ,n41 ii4 #aac ,woods1 ,mr4 ,h41 i4 #bjd ,woodw>d1 ,dr4 ,h5ry1 ii4 #ddi ,woodw>d1 ,mr4 ,h4 ,b41 ii4 #cb1 #dce1 #dec ,worce/]%ire1 late/ eruptive rocks (1 ii4 #aja ,wor?1 ,mr4 ,r4 ,n41 ii4 #ii ,wrek91 i4 #acj ,wright1 ,j4 ,r41 ii4 #ajb ,wuns*1 ,e41 i4 #cfi1 #cib ,wrtemb]g1 puys (1 i4 #df ,wyom+1 lava-fields (1 ii4 #aae ,yates1 ,j41 i4 #aga ,yell[/one ,p>k1 volcanic ph5om5a (1 i4 #bi1 #ca ,y-foel-frs1 i4 #bji1 #bad ,y ,glyd]-,fa*1 i4 #bji ,yor$ale gr\p1 ii4 #i1 #ac1 #ag ,"y1 ,mr4 ,john1 i4 #cfi1 #cib ,"y1 ,pr(4 ,john1 i4 #bid1 #cjh ,zircon1 f\nd 9 volcanic v5ts1 i4 #fb ,zirkel1 ,pr(41 ii4 #cbg1 #cbi1 #ccd1 #cef1 #cfd1 #cgj1 #cgb1 #cgi1 #dcj ,,! ,,end ,pr9t$ by ,r4 ,r4 ,cl>k1 ,limit$1 ,ed9burgh4 ,,! ,,cambridge ,,natural ,,hi/ory4 ,edit$ by ,s4 ,f4 ,h>m]1 ,m4,a1 ,fell[ ( ,k+'s ,college1 ,cambridge1 ,sup]9t5d5t ( ! ,univ]sity ,museum ( ,zoology2 & ,a4 ,e4 ,%ipley1 ,m4,a41 ,fell[ ( ,*ri/'s ,college1 ,cambridge1 ,univ]sity ,lectur] on ! ,morphology ( ,inv]tebrates4 ,to be complet$ 9 ,t5 ,volumes4 #hvo4 price #ags4 net ea*4 ,int5d$ 9 all respects to be a ,/&>d ,natural ,hi/ory accurate en\gh to be ( use to ! ,/ud5t1 & at ! same "t popul> en\gh = ! g5]al read] :o desires tru/wor?y in=mation z to ! /ructure & habits ( all memb]s ( ! ,animal ,k+dom1 f ! ,protozoa to ! ,mammals4 ,! ,volumes are fully illu/rat$ by orig9al figures drawn :]e possible f nature4 ,:5 complete1 ! ,s]ies is "o :i* %\ld be indisp5sable 9 all libr>ies1 :e!r public or private4 ,,n[ ,,ready4 ,,worms1 ,,lee*es1 etc41 ,,volume ,,ii4 ,,flatworms4 ,by ,f4 ,w4 ,gamble1 ,m4,sc41 ,vict41 ,ow5s ,college4 ,,nem]t9es4 ,by ,miss ,l4 ,%eldon1 ,newnham ,college1 ,cambridge4 ,,?read-,,worms1 ,etc4 ,by ,a4 ,e4 ,%ipley1 ,m4,a41 ,fell[ ( ,*ri/'s ,college1 ,cambridge4 ,,rotif]s4 ,by ,m>cus ,h>tog1 ,m4,a41 ,tr9ity ,college1 ,cambridge1 ,d4,sc4 ,lond41 ,pr(essor ( ,natural ,hi/ory 9 ! ,que5's ,college1 ,cork4 ,,poly*aet ,,worms4 ,by ,w4 ,blaxl& ,b5ham1 ,d4,sc4 ,lond41 ,hon4 ,m4,a4 ,oxon41 ,aldri*ian ,demon/rator ( ,comp>ative ,anatomy 9 ! ,univ]sity ( ,ox=d4 ,,e>?worms ,,& ,,lee*es4 ,by ,f4 ,e4 ,b$d>d1 ,m4,a4 ,oxon41 ,f4,r4,s41 ,prosector to ! ,zoological ,society1 ,london4 ,,gephyrea1 ,etc4 ,by ,a4 ,e4 ,%ipley1 ,m4,a41 ,fell[ ( ,*ri/'s ,college1 ,cambridge4 ,,polyzoa4 ,by ,s4 ,f4 ,h>m]1 ,m4,a41 ,fell[ ( ,k+'s ,college1 ,cambridge4 ,,natural ,,sci5ce4--,?is second volume ( ! ,cambridge ,natural ,hi/ory is c]ta9 to prove a mo/ welcome addition to ,engli% ,zoological lit]ature4 ,x deals ) a s]ies ( animal gr\ps1 all deeply int]e/+ to ! speciali/ 9 ,morphology2 "s important f _! economic relations to o!r liv+ ?+s1 o!rs 9 _! life-hi/ories rivall+ ! m>vels ( fairy-tales4 ,& ! /yle 9 :i* !y are "h treat$ is also int]e/+3 hi/ory & ! e>ly obs]vations ( ! old] writ]s l5d _! *>m2 acc\nts ( habits1 & mode ( occurr5ce1 ( life1 9 a ^w1 f ! cradle to ! grave1 are giv5 9 ample detail1 accompani$ by full ref]5ces to mod]n & curr5t lit]ature4 ,! 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