mat]ial f ! ,google ,pr9t project47 ,,*amb]s',s ,,elem5t>y ,,sci5ce ,,manuals4 ,,geology ,,by ,,james ,,geikie1 ,,ll4,d41 ,f4,r4,s4 ,,( ,h4,m4 ,,geological ,,survey2 ,,au?or ,,( ',,! ,,great ,,ice ,,age4' ,logo ,w4 ,r4 ,,*amb]s ,,london ,,& ,,ed9burgh #ahhc ,ed9burgh3 ,pr9t$ by ,w4 & ,r4 ,*amb]s4 ,,preface4 ,! vital importance ( diffus+ "s k ( ! lead+ pr9ciples ( ,sci5ce among all classes ( society1 is becom+ daily m widely & deeply felt2 & to meet & promote ?is important movem5t1 ,w4 ,r4 ,,*amb]s h resolv$ on issu+ ! pres5t ,s]ies ( ,,elem5t>y ,,sci5ce ,,manuals4 ,! ,editors believe t !y enjoy special facilities = ! successful execution ( su* an und]tak+1 ow+ to _! long exp]i5ce--n[ ext5d+ ov] a p]iod ( =ty ye>s--9 ! "w ( popul> education1 z well z to _! hav+ ! co-op]ation ( writ]s specially qualifi$ to treat ! sev]al subjects4 ,9 p>ticul>1 !y are happy 9 hav+ ! editorial assi/ance ( ,,&rew ,,f9dlat]1 ,,ll4,d41 to ^: lab\rs !y 7 s mu* indebt$ 9 ! "w ( edit+ & prep>+ ,*amb]'s ,encyclopa$ia4 ,! ,manuals ( ?is s]ies are int5d$ to s]ve two some:at diff]5t purposes3 #a4 ,!y are design$1 9 ! fir/ place1 = ,,self-,,in/ruction1 & w pres5t1 9 a =m suitable = private /udy1 ! ma9 subjects ent]+ into an enlight5$ education2 s t "y p]sons 9 e>ne/ ab\t self-culture may be able to ma/] !m = !mselves4 #b4 ,! o!r purpose ( ! ,manuals is1 to s]ve z ,,text-,,books ,,9 ,,s*ools4 ,! mode ( treatm5t naturally adopt$ 9 :at is to be /udi$ )\t a tea*]1 s f> f be+ a drawback 9 a s*ool-manual1 w1 x is believ$1 be a positive advantage4 ,in/ead ( a numb] ( abrupt /atem5ts be+ pres5t$1 to be tak5 on tru/ & le>n$1 z has be5 ! usual me?od 9 s*ool-tea*+2 ! subject is made1 z f> z possible1 to unfold itself gradually1 z if ! pupil 7 discov]+ ! pr9ciples himself1 ! *ief function ( ! book be+1 to br+ ! mat]ials be=e him1 & to guide him by ! %orte/ road to ! discov]y4 ,?is is n[ ackn[l$g$ to be ! only pr(itable me?od ( acquir+ k1 :e!r z reg>ds self-in/ruction or le>n+ at s*ool4 ,= simplification 9 tea*+1 ! subject has be5 divid$ into sub-sections or articles1 :i* are numb]$ cont9u\sly2 & a s]ies ( ,que/ions1 9 correspond+ divisions1 has be5 app5d$4 ,^! ,que/ions1 :ile !y w enable ! private /ud5t to te/ = himself h[ f> he has ma/]$ ! sev]al p>ts ( ! subject z he proce$s1 w s]ve ! tea*] ( a class z specim5s ( ! m detail$ & v>i$ exam9ation to :i* he %\ld subject 8 pupils4 ,,note ,,by ,,! ,,au?or4 ,9 ! pres5t ,manual ( ,,geology x has be5 ! aim ( ! au?or r to indicate ! me?ods ( geological inquiry & reason+1 ?an to pres5t ! le>n] ) a t$i\s summ>y ( results4 ,att5tion has !re=e be5 direct$ *iefly to ! physical bran*es ( ! sci5ce--,palaeontology & ,hi/orical ,geology1 :i* are v l>ge subjects ( !mselves1 hav+ be5 only lightly t\*$ ^u4 ,! /ud5t :o has atta9$ to a fair k ( ! scope & be>+ ( ,physical ,geology1 %\ld h little difficulty 9 subsequ5tly tackl+ ^? manuals 9 :i* ! results obta9$ by geological inve/igation are specially treat$ (4 ,,cont5ts4 ,,page ,,introductory #g ,,classification ,,( ,,rocks #h ,,m9]alogy #ab ,,rock-,,=m+ ,,m9]als #ad ,,petrology-- ,,me*anically ,,=m$ ,,rocks #ag ,,*emically ,,=m$ ,,rocks #ai ,,organically ,,d]iv$ ,,rocks #bj ,,metamorphic ,,rocks #ba ,,igne\s ,,rocks #bc ,,/ructure ,,& ,,arrangem5t ,,( ,,rock-,,masses-- ,/ratification1 c42 ,mud-cracks & ,ra9-pr9ts2 ,succession ( ,/rata2 ,ext5t ( ,b$s2 ,sequ5ce ( ,b$s--,jo9ts2 ,cleavage2 ,foliation2 ,concretions2 ,incl9ation ( ,/rata2 ,contemporane\s ,erosion2 ,uncon=mability2 ,ov]lap2 ,faults2 ,mode ( ,occurr5ce ( ,metamorphic & ,igne\s ,rocks2 ,m9]al ,ve9s #bf-df ,,dynamical ,,geology-- ,,! ,,atmosph]e ,,z ,a ,,geological ,,ag5t ,,( ,,*ange #df ,,wat] ,,z ,a ,,geological ,,ag5t ,,( ,,*ange #dh ,,geological ,,action ,,( ,,plants ,,& ,,animals #fj ,,subt]ranean ,,=ces #fd ,,metamorphism #gb ,,physiography #gd ,,palaeontology #gg ,,hi/orical ,,geology #hd ,,que/ions #hi ,illu/ration3 ,,geology ,,introductory4 #a4 ,def9ition4--,geology is ! sci5ce ( ! orig9 & developm5t ( ! /ructure ( ! e>?4 ,x treats ( ! nature & mode ( =mation ( ! v>i\s mat]ials ( :i* ! e>?'s cru/ is compos$2 x seeks to discov] :at mutations ( l& & wat]1 & :at *anges ( climate1 h sup]v5$ dur+ ! pa/2 x endeav\rs to trace ! hi/ory ( ! multitud9\s tribes ( plants & animals :i* h successively t5ant$ our globe4 ,9 a ^w1 ,geology is ! ,physical ,geography ( pa/ ages4 #b4 ,rocks4--,e "o kn[s t ! cru/ ( ! e>? is compos$ ( v v>i\s sub/ances1 "s ( :i* are h>d & cry/all9e 9 texture1 l granite2 o!rs less indurat$ & non-cry/all9e1 su* z s&/one1 *alk1 %ale1 c42 :ile yet o!rs are m or less s(t & incoh]5t masses1 z gravel1 s&1 clay1 peat1 c4 ,n[1 all ^! het]og5e\s mat]ials1 :e!r !y be h>d or s(t1 compact or loose1 granul> or cry/all9e1 are t]m$ rocks4 ,bl[+ s&-dunes1 alluvial silt & s&1 & ev5 peat1 are1 geologically speak+1 rocks1 j z mu* z basalt or any indurat$ build+-/one4 ,! v>iety ( rocks is v great1 b we d n /udy ^! long be=e we become aw>e t _m k9ds :i* pres5t num]\s contra/s 9 detail1 yet possess c]ta9 *>act]s 9 common4 ,& ?is n only gr\ps ^! div]se species toge!r1 b s]ves also to di/+ui% !m f o!r species ( rock1 :i* 9 l mann] are *>act]is$ by ! pres5ce ( "s preval5t g5]ic feature or features4 ,classification ( ,rocks4--,all ! rocks t we "k ( are ?us capable ( be+ arrang$ "u five classes1 z foll[s3 ,i4 ,,me*anically ,,=m$4 ,,ii4 ,,*emically ,,=m$4 ,,iii4 ,,organically ,,d]iv$4 ,,iv4 ,,metamorphic4 ,v4 ,,igne\s4 #c4 ,! ,,me*anically ,,=m$ class comprises a consid]able v>iety ( rocks1 all ( :i*1 h[ev]1 come "u only two subdivisions--namely1 ,s$im5t>y1 & ,eolian or ,a]ial1 ! =m] be+ by f> ! m important4 ,( ! ,s$im5t>y gr\p1 !re are ?ree rocks :i* may be tak5 z typical & repres5tative--namely1 conglom]ate or pudd+/one1 s&/one1 & %ale4 ,a %ort exam9ation ( ! nature ( ^! w suffici5tly expla9 :y !y come to be gr\p$ toge!r "u "o head4 ,conglom]ate consi/s ( a mass ( v>i\s-siz$ r\nd$ /ones cem5t$ toge!r2 ea* /one has be5 well rubb$1 & roll$1 & r\nd$4 ,x is q obvi\s t ! n[ solid rock mu/ at "o "t h exi/$ 9 a loose & unconsolidat$ /ate1 l gravel & %+le4 ,nor c we resi/ ! conclusion t ! /ones 7 at "o "t roll$ ab\t by ! action ( wat]--t be+ ! only mode 9 :i* gravel-/ones are %ap$4 ,aga91 :5 we h an opportunity ( exam9+ any consid]able v]tical ?ickness ( conglom]ate1 we %all frequ5tly obs]ve t ! /ones are arrang$ m or less def9itely along c]ta9 l9es4 ,^!1 !re c be no "q1 are l9es ( deposition--! r\nd$ /ones h evid5tly n be5 =m$ & accumulat$ all at once1 b pil$ up gradually1 lay] ^u lay]4 ,& s9ce !re is no =ce 9 nature1 t we "k (1 save wat] 9 motion1 t c\ld s r\nd & smoo? /ones1 & spread !m out 9 successive lay]s or b$s1 we may n[ amplify our def9ition ( conglom]ate1 & describe x z a compact$ mass ( /ones :i* h be5 m or less r\nd$1 & arrang$ 9 m or less di/9ct lay]s or b$s1 by ! action ( wat]4 #d4 ,s&/one may at ! outset be describ$ z a granul> non-cry/all9e rock4 ,?is rock %ews e degree ( co>s5ess1 f a mass 9 :i* ! con/itu5t gra9s are ne>ly z l>ge z turnip-se$1 d[n to a /one s f9e 9 ! gra9 t we ne$ a l5s to discov] :at ! p>ticles are ( :i* x is compos$4 ,:5 ^! latt] are exam9$1 !y are f\nd to exhibit m>ks ( attrition1 j l ! /ones ( a conglom]ate4 ,%>p edges h be5 worn (f1 & ! gra9s r\nd$ & rubb$2 & :]eas l9es ( deposition are (t5 obscure1 & ( infrequ5t occurr5ce 9 conglom]ate--9 s&/one1 on ! contr>y1 !y are usually well m>k$ & (t5 abundant4 ,we c h>dly d\bt1 !re=e1 t s&/one has also _h an aque\s orig91 or 9 o!r words1 t x has be5 =m$ & accumulat$ by ! =ce ( wat] 9 motion4 ,9 %ort1 s&/one is m]ely compact$ s&4 #e4 ,if x be easy to read ! orig9 ( conglom]ate & s& 9 ! ext]nal "* ( _! +r$i5ts1 & ! mode 9 :i* ^! h be5 arrang$1 we %all f9d x n less easy to discov] ! orig9 ( %ale4 ,%ale is1 l s&/one1 a granul> non-cry/all9e rock4 ,! p>ticles ( :i* x is built up are usually too small to be di/+ui%$ )\t ! aid ( a l5s1 b :5 put "u a suffici5t magnify+ p[]1 !y exhibit evid5t m>ks ( attrition4 ,9 /ructure x diff]s widely f s&/one4 ,9 ! latt] rock ! lay]s ( deposition1 ?\gh frequ5tly num]\s1 are yet sep>at$ f ea* o!r by "s consid]able di/ance1 x may be by a few in*es or by _m y>ds4 ,b 9 %ale ! lay]s are s ?9 t we may split ! rock into lam9ae or plates4 ,n[ we "k t _m s$im5t>y mat]ials ( rec5t orig91 su* z ! silt ( lakes1 riv]s1 & e/u>ies1 al?\gh :5 newly dug into !y appe> to be m or less homog5e\s1 & %ew b few l9es ( deposition1 yet :5 expos$ to ! action ( ! atmosph]e & dri$1 !y v (t5 split up into lay]s exhibit+ division planes z m9ute z any obs]vable 9 %ale4 ,!re is no reason to d\bt1 !re=e1 t %ale is m]ely compact$ silt & mud--! s$im5t deposit$ by wat]4 ,x becomes evid5t1 !re=e1 t conglom]ate1 s&/one1 & %ale are t]ms ( "o s]ies4 ,!y are all equally s$im5t>y deposits1 & ?us1 if we slightly modify our def9ition ( conglom]ate1 we %all h a def9ition :i* w include ! ?ree rocks we h be5 consid]+4 ,= !y may all be describ$ z granul> non-cry/all9e rocks1 ! con/itu5t +r$i5ts ( :i* h be5 m or less r\nd$1 & arrang$ 9 m or less di/9ct lay]s1 by ! action ( wat]4 #f4 ,! ,eolian or ,a]ial gr\p ( rocks embraces all natural accumulations ( organic or inorganic mat]ials1 :i* h be5 =m$ ^u ! l&4 ,! gr\p is typically repres5t$ by debris1 su* z ga!rs on hill-slopes & at ! base ( cliffs1 by ! s&-hills ( des]ts & m>itime di/ricts1 & by soil4 ,all ^! accumulations owe _! orig9 to atmosph]ic ag5cies1 z w be m p>ticul>ly describ$ 9 ! sequel4 ,z ! ,s$im5t>y & ,eolian rocks are ! results ( ! me*anical action ( wat] & ! atmosph]e1 !y are fitly arrang$ "u "o great class--! ,,me*anically ,,=m$ ,,rocks4 #g4 ,,*emically ,,=m$ ,,rocks con/itute ano!r well-m>k$ class1 ( :i* we may take rock-salt z a typical example4 ,?is rock has evid5tly be5 deposit$ 9 wat]1 b n 9 ! mann] ( a s$im5t>y b$4 ,x is n built up ( wat]-worn p>ticles :i* h be5 roll$ ab\t & accumulat$ lay] ^u lay]1 b has be5 sl[ly precipitat$ dur+ ! gradual evaporation ( wat] 9 :i* x 0 previ\sly held 9 solution4 ,its =mation is !re=e a *emical process4 ,v>i\s o!r rocks come "u ! same category1 z we %all aft]w>ds po9t out4 #h4 ,! ,,organically ,,d]iv$ class comprises a numb] ( ! mo/ important & useful rock-masses4 ,*alk may be select$ z a typical example4 ,ev5 a slight exam9ation %ews t ?is rock diff]s widely f any ( ^? m5tion$ above4 ,conglom]ate1 s&/one1 %ale1 c4 are built up ( pebbles1 p>ticles1 gra9s1 c4 ( v>i\s inorganic mat]ials4 ,b *alk1 :5 look$ at "u ! microscope1 betrays an organic orig94 ,x consi/s1 *iefly1 ( ! h>d calc>e\s p>ts ( animal organisms1 & is m or less abundantly /ock$ ) ! rema9s ( corals1 %ells1 cru/aceans1 c4 9 e degree ( pres]vation2 inde$1 s abundant are ^! relics1 t !y g to =m a great proportion ( ! rock4 ,coal is ano!r famili> example ( an organically d]iv$ rock1 s9ce x consi/s entirely ( vegetable rema9s4 #i4 ,! ,,metamorphic class1 z ! "n implies1 embraces all ^? rocks :i* h und]gone "s decid$ *ange s9ce ! "t ( _! =mation4 ,?is *ange g5]ally consi/s 9 a re-arrangem5t ( _! con/itu5t elem5ts1 & has frequ5tly result$ 9 giv+ a cry/all9e texture to ! rocks affect$4 ,h5ce c]ta9 s$im5t>y deposits l s&/one & %ale h be5 *ang$ f granul> into cry/all9e rocks1 & ! l has happ5$ to b$s ( lime/one & *alk4 ,mica-s*i/1 gneiss1 & sac*>oid m>ble are typical ( ?is class4 #aj4 ,! ,,igne\s rocks are ^? :i* owe _! orig9 to ! action ( ! int]nal =ces ( ! e>?'s cru/4 ,mo/ ( !m h be5 9 a /ate ( fusion1 & betray _! orig9 by _! cry/all9e & sometimes glassy texture1 & also1 z we %all see 9 ano!r section1 by ! mode ( _! occurr5ce4 ,lava1 basalt1 & obsidian are *>act]i/ic types ( ?is gr\p ( igne\s rocks4 ,ano!r gr\p embraces a l>ge v>iety ( igne\s rocks :i* are non-cry/all9e1 & v>y 9 texture f f9e-gra9$1 almo/ compact1 b$d$ masses1 l c]ta9 v>ieties ( tuff1 up to co>se1 irregul> accumulations ( angul> /ones imb$d$ 9 a f9e-gra9$ or gritty matrix1 l volcanic breccia & volcanic agglom]ate4 ,,m9]alogy4 #aa4 ,hav+ le>n$ t all ! rocks met ) at ! surface ( ! e>?'s cru/ are capable ( be+ arrang$ "u a few classes1 we h n[ to inve/igate ! matt] m 9 detail4 ,x w be obs]v$ t ! classification adopt$ above is bas$ *iefly ^u ! ext]nal *>act]s ( ! con/itu5t +r$i5ts ( ! rocks1 & ! mode 9 :i* ^! p>ticles h be5 collect$4 ,9 "s rocks ! compon5t mat]ials are cry/all9e1 9 o!rs !y are r\nd$ & worn2 9 "o case !y h be5 br\ght toge!r by precipitation f an aque\s solution1 or !y h cry/allis$ out f a mass ( once molt5 matt]2 9 ano!r case _! collection & intimate association is due to ! me*anical action ( ! atmosph]e or ( wat]1 or to ! ag5cy ( ! organic =ces4 ,we h next to inquire :at is ! nature ( ^? cry/als & p>ticles :i* are ! +r$i5ts ( ! rocks8 ,! answ] to ?is "q prop]ly belongs to ! sci5ce ( m9]alogy1 ) :i*1 h[ev]1 ! geologi/ mu/ necess>ily make "s acqua9tance4 #ab4 ,granite--its composition4--,x w t5d to simplify matt]s if we beg9 our inquiry by select+ = exam9ation "s famili> rock1 su* z granite4 ,?is rock1 z "o sees at a glance1 is cry/all9e1 nor is x difficult to p]ceive t ?ree sep>ate k9ds ( +r$i5ts g to compose x4 ,"o ( ^! we %all obs]ve is a gray1 or x may be1 cle> glassy-look+ sub/ance1 :i* is h>d1 & w n scrat* ) a knife2 ano!r is ( a p9k1 r$1 gray1 or sometimes ev5 pale gre5 col\r1 & scrat*es ) difficulty2 :ile ! ?ird %ews a gli/]+ metallic lu/re1 & is g5]ally ( a br[ni% or black col\r4 ,x scrat*es easily ) ! knife1 & c be split up into flakes ( extreme ?9ness4 ,if ! granite be "o ( ! co>se-gra9$ v>ieties1 we %all notice t ^! ?ree +r$i5ts h ea* m or less def9ite cry/all9e =ms2 s t !y are n di/+ui%$ by col\r & h>dness alone4 ,! metallic-look+ sub/ance is mica2 ! h>d gray1 or glassy & unscrat*able +r$i5t is qu>tz2 & ! rema9+ mat]ial is felsp>4 ,! m9]alogi/'s analysis ( granite ends "h4 ,b !re is /ill mu* to be le>n$ ab\t qu>tz1 felsp>1 & mica2 =1 z ! *emi/ w tell u1 ^! are n 'elem5t>y sub/ances4' ,qu>tz is a comp\nd1 consi/+ ( two elem5ts1 "o ( :i* is a non-metallic body 7silicon71 & ! o!r an invisible gas 7oxyg574 ,felsp>,a is a /ill m complex comp\nd1 be+ made up ( two metals 7potassium1 alum9ium7 & "o non-metallic body 7silicon71 ea* ( :i* is unit$ to an invisible gas 7oxyg574 ,mica1 aga91 conta9s no few] ?an f\r metals 7potassium1 magnesium1 iron1 calcium7 & "o non-metallic body 7silicon71 ea* ( :i* is 9 l mann] *emically unit$ to its %>e ( oxyg54 ,?us ! rock-=m+ sub/ances1 qu>tz1 felsp>1 & mica1 h ea* a def9ite *emical composition4 #ac4 ,m9]als4--,n[1 any inorganic sub/ance :i* has a def9ite *emical composition1 & cry/allises 9 a def9ite cry/all9e or geometric =m1 is t]m$ a m9]al4 ,hav+ once discov]$ t qu>tz is compos$ ( silicon & oxyg5--t is1 silica--& t ! faces ( its cry/als are arrang$ 9 a c]ta9 def9ite ord]1 we may be q sure t any m9]al :i* has n ?is composition & =m _c be qu>tz4 ,& s on ) mica & felsp>1 & e o!r m9]al4 ,! /udy ( ! geometric =ms assum$ by m9]als 7cry/allography7 =ms a dep>tm5t ( ! sci5ce ( m9]alogy4 ,b1 9 ! great majority ( cases1 ! m9]al +r$i5ts ( ! rocks are ei!r s small individually1 or s brok51 & r\nd$1 & alt]$1 t cry/allography gives comp>atively little aid to ! practical geologi/ 9 ! field4 ,he has1 !re=e1 rec\rse to o!r te/s = ! det]m9ation ( ! m9]al con/itu5ts ( rocks4 ,_m ( ^! te/s1 h[ev]1 c only be appli$ by ^? :o h _h long exp]i5ce4 ,! simple/ & easie/ way = ! /ud5t to beg9 is to exam9e ! =ms & appe>ance ( ! m common m9]als 9 "s collection1 & !reaft] to accu/om 8 eye to ! aspect pres5t$ by ! same m9]als :5 !y are associat$ toge!r 9 rocks1 ( :i* illu/rative specim5s are n[ to be met ) 9 mo/ museums4 ,! microscope is l>gely employ$ by geologi/s = det]m9+ ! m9]alogical composition ( c]ta9 rocks2 &1 inde$1 _m rocks c h>dly be said to be ?or\ghly kn[n until !y h be5 slic$ & exam9$ "u ! microscope1 & analys$ by ! *emi/4 ,b ) a va/ numb] su* m9ute exam9ation is n requir$1 ! eye aft] "s practice be+ able to detect all t is ne$ful to be kn[n4 ,a ,!re are v>i\s k9ds ( felsp>2 ! "o ref]r$ to above is or?oclase1 or pota%-felsp>4 ,,rock-,,=m+ ,,m9]als4 #ad4 ,ne>ly all ! m9]als we "k ( conta9 oxyg5 z a necess>y +r$i5t1 !re be+ only a v few m9]als 9 :i* t gas does n occur 9 *emical union ) o!r elem5ts4 ,?ree ( ^! m9]als1 sulphur1 ! diamond1 & graphite1 consi/ ( simple sub/ances1 & are ( great comm]cial importance1 b none ( !m is ( s frequ5t occurr5ce1 z a rock con/itu5t1 z ! m9]als pres5tly to be describ$4 ,sulphur occurs sometimes 9 ?9 b$s1 b m frequ5tly 9 small ne/s & nodules1 c4 9 o!r rocks1 or 9 jo9ts1 & fissures1 & ve9s4 ,x is frequ5tly f\nd 9 volcanic di/ricts4 ,! diamond1 :i* consi/s ( pure c>bon1 is g5]ally met ) 9 alluvial deposits1 b sometimes1 also1 9 a curi\s flexible s&/one1 call$ itacolumite4 ,graphite is ano!r =m ( c>bon4 ,x occurs bo? 9 a cry/all9e & amorph\s =m1 ! latt]1 or non-cry/all9e k9d1 be+ ext5sively us$ = lead-p5cils4 ,rock-salt is a *loride ( sodium1 & appe>s sometimes 9 masses ( a hundr$ feet & m 9 ?ickness4 ,ano!r m9]al :i* conta9s no oxyg5 is ! well-kn[n fluor-sp>4 ,x occurs *iefly 9 ve9s1 & is (t5 associat$ ) ores4 ,) ^!1 & a few o!r exceptions1 all ! m9]als hi!rto discov]$ conta9 oxyg5 z an ess5tial elem5t2 & s l>ge is ! proportion ( ?is gas :i* ent]s into union ) o!r elem5ts to con/itute ! v>i\s m9]als ( :i* ! rocks are compos$1 t x =ms at lea/ "o-half ( all ! pond]able matt] ne> ! e>?'s surface4 ,:5 ! /ud5t le>ns t !re are probably no few] ?an six or sev5 hundr$ diff]5t m9]als1 he w und]/& h[ impossible x is to d m 9 a %ort geological treatise ?an po9t out a few ( ! mo/ commonly occurr+ ones4 ,&1 inde$1 a k ( ! *ief rock-=m+ m9]als1 :i* are few 9 numb]1 is all t is absolutely requisite = geological purposes4 ,"s ( ^! we accord+ly proce$ to "n4,b ,b ,x is ne$less to describe ! m9]als m9utely "h4 ,! /ud5t c only le>n to di/+ui% ! diff]5t species by c>efully exam9+ actual specim5s4 #ae4 ,qu>tz4--,?is m9]al has already be5 p>tially describ$4 ,x is ! mo/ abundant ( all ! rock-=m+ m9]als1 & occurs 9 ?ree =ms3 7#a7 cry/allis$ qu>tz or rock cry/al2 7#b7 *alc$ony1 bo? ( :i* are compos$ ( silica--t is1 silicon & oxyg52 & 7#c7 hydrat$ qu>tz--t is1 silica ) ! addition ( wat]4 ,hematite4--,?is is an oxide ( iron4 ,x occurs 9 mammill>y r\nd$ masses1 ) a fibr\s /ructure1 & a dull metallic lu/re4 ,magnetite or magnetic iron ore1 specul> iron1 & limonite are also oxides ( iron4 ,hematite %ews a r$ /reak :5 scrat*$ ) a knife1 :i* di/+ui%es x f magnetite4 ,iron pyrites4--,?is is a sulphide ( iron ( v common occurr5ce4 ,its cry/all9e =m is cubical4 ,:5 brok51 x emits a sulphur\s smell4 ,! brass-yell[ col\r$ cubes s (t5 se5 9 ro(+-slates are famili> examples ( ! mode ( its occurr5ce4 ,b x is also frequ5tly f\nd 9 masses hav+ a cry/all9e surface4 #af4 ,,sulphates4--,only two sulphates may be notic$--namely1 gypsum1 :i* is a sulphate ( lime1 ) its v>ieties1 sel5ite1 sat9-sp>1 & alaba/]2 & b>ytes1 a sulphate ( b>yta4 ,b>ytes scrat*es easily ) ! knife1 & f its great specific gravity is (t5 call$ heavy-sp>4 ,gypsum is s(t] ?an b>ytes4 ,,c>bonates4--,two ( ^! only ne$ be m5tion$3 calcite or calc-sp>1 a c>bonate ( lime1 :i* scrat*es ) ! knife1 & eff]vesces readily ) dilute hydro*loric acid2 & arragonite1 also a c>bonate ( lime1 b d5s] ?an calcite4 ,,silicates4--,^! are by f> ! mo/ abundantly occurr+ m9]als4 ,! species are also exce$+ly num]\s1 b we may note "h only a few ( ! m important4 ,!y are compos$ ( silica & v>i\s bases1 su* z lime1 pota%1 magnesia1 soda1 alum9a1 c4 ,augite or pyrox5e is a black or gre5i%-black m9]al1 f\nd1 ei!r z cry/als1 :i* are g5]ally small1 or z r\nd$ gra9s & angul> fragm5ts1 9 basaltic & volcanic rocks4 ,x nev] occurs 9 granite rocks4 ,x is brittle1 & has a vitre\s or res9\s lu/re4 ,!re are a numb] ( v>ieties or sub-species ( augite4 ,hornbl5de1 l augite1 also includes a great _m m9]als4 ,:5 ! cry/als are small1 x is (t5 difficult to di/+ui% hornbl5de f augite4 ,common hornbl5de occurs cry/allis$ or massive1 & is d>k gre5 or black1 ) a vitre\s lu/re4 ,x is g5]ally sub-transluc5t4 ,x usually cry/allises 9 igne\s rocks :i* conta9 mu* qu>tz or silica2 :ile augite1 on ! o!r h&1 cry/allises 9 igne\s rocks :i* are ( a m basic "*--t is to say1 rocks 9 :i* silica is n s abundantly pres5t4 ,felsp> is a g5]ic t]m :i* embraces a numb] ( species1 su* z or?oclase or pota%-felsp>1 albite or soda-felsp>1 & anor?ite or lime-felsp>4 ,or?oclase is :ite1 r$ or p9k1 & gray4 ,x is "o ( ! ord9>y con/itu5ts ( granite1 & ent]s into ! composition ( _m rocks4 ,albite is usually :ite4 ,x (t5 occurs z a con/itu5t ( granite1 n unfrequ5tly be+ associat$ 9 ! same rock ) p9k felsp> or or?oclase4 ,9 sy5ite & gre5/one x occurs m commonly ?an or?oclase4 ,anor?ite occurs 9 :ite transluc5t or transp>5t cry/als4 ,x is n s common a con/itu5t ( rocks z ei!r ( ! o!r felsp>s j ref]r$ to4 ,mica3 ?is t]m includes sev]al m9]als1 :i* all agree 9 be+ highly cleavable into ?9 ela/ic flakes or lam9ae1 :i* h a gli/5+ metallic lu/re4 ,mica is "o ( ! common con/itu5ts ( granite4 ,talc is a silv]y :ite1 grayi%1 pale or d>k-gre5 col\r$ m9]al1 ) a pe>ly lu/re4 ,x splits readily into ?9 flakes1 :i* are flexible1 b n ela/ic1 & may be readily scrat*$ ) ! nail4 ,x is unctu\s & greasy to ! t\*4 ,x occurs 9 b$s 7talc-slate71 & is (t5 met ) 9 di/ricts occupi$ by metamorphic cry/all9e rocks4 ,s]p5t9e is g5]ally ( a gre5 col\r1 b br[n1 r$1 & v>i\sly mottl$ v>ieties occur4 ,x has a dull lu/re1 & is s(t1 & easily cut2 x is t\gh1 h[ev]1 & takes on a good poli%4 ,x =ms rock-masses 9 "s places4 ,! f9] v>ieties are call$ noble s]p5t9e4 ,*lorite is ano!r s(t1 easily scrat*$ m9]al1 g5]ally ( a d>k-gre5 col\r4 ,x has a pe>ly lu/re4 ,sometimes x occurs 9 b$s 7*lorite-slate71 & is (t5 f\nd coat+ ! walls ( fissures 9 c]ta9 rocks4 ,x has a some:at greasy feel4 ,! ?ree la/-m5tion$ m9]als--talc1 s]p5t9e1 & *lorite--are all silicates ( magnesia4 ,zeolites is a t]m :i* comprises a numb] ( m9]als ( v>y+ *emical composition1 all ( :i* t5d to =m a jelly :5 treat$ ) acids4 ,:5 heat$ by ! bl[-pipe !y bubble up1 ow+ to ! escape ( wat]2 h5ce _! "n zeolites1 f zeo1 ,i boil1 & li?os1 a /one4 ,! zeolites occur v commonly 9 cavities 9 igne\s rocks1 & also 9 m9]al ve9s4 ,hav+ n[ m5tion$ ! *ief rock-=m+ m9]als1 we proce$ to a brief description ( "s ( ! m typical repres5tatives ( ! five great classes ( rocks ref]r$ to at page #h4 ,,petrology4,c ,c ,petros1 a rock1 & logos1 a disc\rse4 ,"s geologi/s re/rict ?is t]m to ! /udy ( ! /ructure & arrangem5t ( rock-masses1 & apply ! t]m li?ology 7li?os1 a /one1 & logos1 a disc\rse7 to ! /udy ( ! m9]alogical composition ( rocks4 ,,me*anically ,,=m$ ,,rocks4 #ag4 7,a47 ,,s$im5t>y ,,class4--,?ree ( ! mo/ commonly occurr+ rocks ( ?is class h already be5 describ$1 b a few details are add$ "h4 ,conglom]ate4--,?is is a consolidat$ mass ( m or less wat]-worn & r\nd$ /ones4 ,^! /ones may be ( any size4 ,:5 !y are v l>ge1 ! rock is call$ a co>se conglom]ate2 ! f9] v>ieties1 9 :i* ! /ones are small1 are kn[n z pebbly conglom]ates4 ,! +r$i5ts ( a conglom]ate may consi/ ( any k9d ( rock1 or ( a mixture ( _m diff]5t k9ds4 ,:5 !y consi/ entirely ( qu>tz1 ! rock becomes qu>tzose4 ,! f9]-gra9$ conglom]ates usually %ew l9es ( deposition or b$d+1 b 9 "s ( ! co>s] sorts x is (t5 difficult to detect any k9d ( arrangem5t4 ,! /ones are usually imb$d$ 9 a matrix ( qu>tzose grit & s&1 b sometimes ?is is v scanty4 ,:5 ! nature ( ! mat]ial :i* b9ds ! /ones toge!r is v well m>k$1 ! rock becomes f]rug9\s1 calc>e\s1 ar5ace\s1 or argillace\s1 accord+ z ! b9d+ or cem5t+ mat]ial is iron1 lime1 s&1 or clay4 ,breccia is a rock 9 :i* ! includ$ fragm5ts are angul>4 #ah4 ,s&/one is1 z already rem>k$1 m]ely consolidat$ s&4 ,! co>s] v>ieties1 9 :i* ! gra9s are z l>ge & l>g] ?an turnip-se$s1 are t]m$ grit4 ,f ^! co>se v>ieties ! rock passes ins5sibly1 9 "o direction1 into a f9e or pebbly conglom]ate1 & 9 ano!r into a rock1 s f9e-gra9$ t a l5s is ne$$ to di/+ui% ! compon5t p>ticles4 ,qu>tz is ! prevail+ +r$i5t--sometimes cle>1 at o!r times :ite4 ,frequ5tly1 h[ev]1 ! gra9s are coat$ ) an oxide ( iron1 :i* gives ! result+ rock a r$ col\r4 ,! o!r col\rs assum$ by s&/one--su* z yell[1 br[n1 gre51 c4--are also 9 l mann] due to ! pres5ce ( "s comp\nd ( iron4 ,:5 mica or felsp> occurs pl5tifully1 we h1 9 ! "o case1 micace\s s&/one1 & 9 ! o!r felspa?ic s&/one4 ,a s&/one 9 :i* ! gra9s are cem5t$ by c>bonate ( lime is said to be calc>e\s4 ,free/one is a s&/one :i* c be work$ freely 9 any direction4 ,9 mo/ s&/ones1 ! l9es ( b$d+ are di/9ct2 :5 !y are s num]\s z to r5d] ! rock fissile1 ! s&/one is said to be %aly4 ,%ale is a m or less indurat$ fissile or lam9at$ clay4 ,:5 ! rock becomes co>se by ! admixture ( s&1 x gradually passes into a %aly s&/one4 ,!re are _m o!r v>ieties ( clay-rocks--su* z fire-clay1 pipe-clay1 m>l1 loam1 c4--:i* are suffici5tly famili>4 #ai4 7,b47 ,,eolian or ,,a]ial ,,class4--,bl[n-s& is f\nd at _m places on sea-coa/s4 ,x g5]ally =ms smoo? r\nd$ hummocks1 :i* are sometimes arrang$ 9 long l9es p>allel to ! tr5d ( ! coa/1 z1 = example1 9 ! ,t5ts ,moor1 ne> ,/ ,&rews4 ,! s&-hills ( des]ts also belong to ?is class4 ,debris is ! loose angul> rubbi% :i* collects at ! base ( cliffs1 on hill-tops1 & hill-slopes4 ,imm5se accumulations ( x occur 9 l(ty m\nta9\s di/ricts & 9 arctic regions4 ,9 ,nova ,zembla1 = example1 ! solid rock ( ! c\ntry is almo/ conceal$ b5ea? a ?ick cov]+ ( debris4 ,b ! v>i\s k9ds ( debris w be m p>ticul>ly describ$ fur!r on4 ,soil4--,an acc\nt ( ?is c h>dly be giv5 )\t ent]+ into ! !ory ( its orig91 & !re=e we res]ve its consid]ation = ! pres5t4 ,,*emically ,,=m$ ,,rocks4 #bj4 ,/alactites & /alagmites are c>bonates ( lime4 ,!y v>y 9 col\r1 be+ :ite1 or yell[1 or br[n4 ,/alactites are usually f\nd adh]+ to ! ro(s ( lime/one cav]ns1 c41 or dep5d+ f lime/one rocks2 /alagmites1 on ! o!r h&1 commonly occur on ! floors ( lime/one cav]ns1 :]e !y (t5 atta9 a ?ickness ( _m feet4 ,silice\s s9t] is silica ) ! addition ( wat]--9 o!r words1 a hydrat$ qu>tz4 ,x is n a v abundant rock1 & is f\nd *iefly 9 volcanic c\ntries4 ,rock-salt has already be5 describ$4 ,x occurs ei!r z ?9 b$s1 or 9 ! =m ( ?ick cake-l masses1 (t5 rea*+ n9ety or "o hundr$ feet 9 ?ickness4 ,x is rudely cry/all9e 9 texture1 & is usually discol\r$ br[n & r$ ) v>i\s impurities4 ,,organically ,,d]iv$ ,,rocks4 #ba4 ,lime/one consi/s ( c>bonate ( lime1 b usually conta9s "s impurities4 ,! v>ieties ( ?is rock are num]\s2 "s ( !m are z foll[s3 ,*alk2 oolite1 a rock built up ( little sph]oidal concretions1 :5ce its "n1 egg or roe /one 7! co>s] oolites are call$ pisolite1 or pea-/one72 lacu/r9e lime/one1 c4 ,:5 mu* silica is diffus$ ?r\gh ! rock1 we h a silice\s lime/one2 ! pres5ce ( clay & ( c>bonace\s matt] gives u argillace\s & c>bonace\s lime/ones4 ,corn/one is a lime/one conta9+ a l>ge quantity ( ar5ace\s matt] or s&4 ,_m lime/ones are di/+ui%$ by ! diff]5t k9ds ( organic rema9s :i* !y yield4 ,?us1 we h mus*elkalk or %ell-lime/one1 nummulitic1 cr9oidal1 c4 lime/one4 ,! cry/all9e lime/ones1 su* z /atu>y m>ble1 are metamorphos$ lime/ones4 ,n a few lime/ones are *emically =m$ rocks1 & _m1 also1 are p>tly ( *emical & p>tly ( organic orig91 s t no h>d & fa/ l9e c be drawn betwe5 ^! two classes ( rock4 ,dolomite1 or magnesian lime/one4--,?is is a comp\nd ( c>bonate ( lime & c>bonate ( magnesia4 ,its col\r is usually yell[1 or yell[i% br[n1 b gray & black v>ieties are sometimes met )4 ,x is g5]ally f9e-gra9$1 ) a cry/all9e texture1 & pe>ly lu/re4 ,x eff]vesces less freely ) acids ?an pure lime/one4 ,9 _m cases dolomite is m]ely a metamorphos$ lime/one4 #bb4 ,coal is compos$ ( vegetable matt]1 b usually conta9s a great] or less p]c5tage ( impurities4 ,! v>ieties ( ?is sub/ance are v num]\s1 & diff] f ea* o!r pr9cipally 9 reg>d to _! bitum9\s or non-bitum9\s "*4 ,coal is bitum9\s or non-bitum9\s accord+ z x is less or m highly m9]alis$4 ,bitum5 results f ! decomposition ( vegetable matt]2 b1 :5 ! m9]alis+ process 7to :i* ! =mation ( coal is due7 has proce$$ f> en\gh1 ! vegetable matt] gradually loses its bitum9\s "*1 & ! result is a non-bitum9\s coal4 ,v>ieties ( coal are ! foll[+3 ,lignite or br[n coal2 cak+ coal2 cannel1 p>rot1 or gas coal2 spl9t coal2 *]ry or s(t coal2 an?racite or bl9d coal1 s call$ because x burns ) no flame4 ,peat may be m5tion$ z ano!r natural fuel4 ,x is compos$ ( vegetable matt]4 ,9 "s k9ds x is s f> decompos$1 or m9]alis$1 t ! eye does n detect vegetable fibres2 :5 ?or\ghly dri$1 su* peat breaks l a good lignite1 & =ms an excell5t fuel4 ,,metamorphic ,,rocks4 #bc4 ,qu>tz-rock1 or qu>tzite1 is an alt]$ qu>tzose s&/one or grit2 x is g5]ally a :ite or grayi%-yell[ rock1 v h>d & compact4 ,! orig9al gritty "* ( ! rock is di/9ct1 b ! granules appe> z if !y _h be5 fus$ s f> z to become mutually adh]5t4 ,:5 ! alt]$ s&/one has be5 compos$ ( gra9s ( qu>tz1 felsp>1 or mica1 set 9 a silice\s1 felspa?ic1 or argillace\s base1 we get a rock call$ greywacke1 :i* is usually gray or grayi% blue 9 col\r4 #bd4 ,clay-slate is a grayi% blue1 or gre51 f9e-gra9$ h>d rock1 :i* splits into num]\s m or less ?9 lam9ae1 :i* may or may n co9cide ) ! orig9al b$d+4 ,mo/ usually ! 'cleavage1' z ?is fissile /ructure is t]m$1 crosses ! b$d+ at all angles4 #be4 ,cry/all9e lime/one is an alt]$ condition ( common lime/one4 ,sac*>oid m>ble is "o ( ! f9e v>ieties3 x frequ5tly conta9s flakes ( mica4 ,dolomite1 or magnesian lime/one1 already describ$1 is probably 9 _m cases an alt]$ lime/one2 ! c>bonate ( lime hav+ be5 p>tially dissolv$ out & replac$ by c>bonate ( magnesia4 ,s]p5t9e is also believ$ by "s geologi/s to be a highly metamorphos$ magnesian lime/one4 #bf4 ,s*i/s4--,"u ?is t]m comes a great v>iety ( cry/all9e rocks :i* all agree 9 hav+ a foliat$ texture--t is to say1 ! con/itu5t m9]als are arrang$ 9 lay]s :i* usually1 b n inv>iably1 co9cide ) ! orig9al b$d+4 ,among/ ! s*i/s come mica-s*i/ 7qu>tz & mica 9 alt]nate lay]s72 *lorite-s*i/ 7*lorite ) a little qu>tz1 & sometimes ) felsp> or mica72 talc-s*i/ 7talc ) qu>tz or felsp>72 hornbl5de s*i/ 7hornbl5de ) a v>iable quantity ( felsp>1 & sometimes a little qu>tz72 gneiss 7qu>tz1 felsp>1 & mica74 #bg4 ,g5]al ,"* ( ,metamorphic ,rocks4--,all ^! rocks betray _! aque\s orig9 by ! pres5ce ( m or less di/9ct l9es ( b$d+4 ,!y consi/ ( v>i\s k9ds ( ar5ace\s & argillace\s deposits1 :i*1 "u ! influ5ce ( c]ta9 metamorphic actions1 to be describ$ 9 ! sequel1 h lo/ _! orig9al granul> texture1 & become m or less di/9ctly cry/allis$4 ,& n only s1 b _! *emical +r$i5ts h 9 _m cases ent]$ into new relations1 s z to give rise to m9]als :i* exi/$ ei!r sp>+ly or n at all 9 ! orig9al rocks4 ,frequ5tly1 x is q impossible to say :at 0 ! orig9al condition ( "s metamorphic rocks2 (t51 h[ev]1 ?is is suffici5tly obvi\s4 ,?us1 highly micace\s s&/ones1 z !y are trac$ into a metamorphic region1 are se5 to pass gradually into mica-s*i/4 ,:5 ! b$d+ ( gneiss becomes entirely oblit]at$1 x is (t5 difficult to di/+ui% t rock f granite1 & 9 _m cases x appe>s to pass into a true granite4 #bh4 ,granite is a cry/all9e comp\nd ( qu>tz1 felsp> 7usually pota%-felsp>71 & mica4 ,"s geologi/s consid] x to be inv>iably an igne\s rock2 b1 z j /at$1 x sometimes passes into gneiss 9 su* a way z to lead u to inf] its metamorphic orig94 ,!re are c]ta9 areas ( s&/one 9 ! s\? ( ,scotl& :i* are p>tially metamorphos$1 & 9 ^! we may trace a gradual passage f highly bak$ felspa?ic s&/ones ) a sub-cry/all9e texture into a m cry/all9e rock :i* 9 places graduates into true granite4 ,granite1 h[ev]1 also occurs z an igne\s rock4 #bi4 ,sy5ite is a cry/all9e comp\nd ( a pota%-felsp> & hornbl5de1 & qu>tz is frequ5tly pres5t4 ,diorite is a cry/all9e aggregate ( a soda-felsp> & hornbl5de4 ,bo? sy5ite & diorite also occur z igne\s rocks4 ,!re are a numb] ( o!r metamorphic rocks1 b ^? m5tion$ are ! mo/ commonly occurr+ species4 ,,igne\s ,,rocks4 #cj4 ,subdivisions4--,9 _! *emical & m9]alogical composition1 igne\s rocks (f] great v>iety2 b !y all agree 9 hav+ felsp> = _! base4 ,!y may be r\ghly divid$ into two classes1 di/+ui%$ by ! relative quantity ( silica :i* !y conta94 ,^? 9 :i* ! silica ranges f ab\t #ej to #gj or #hj p] c5t4 =m :at is t]m$ ! acidic gr\p2 :ile ^? 9 :i* ! p]c5tage ( silica is less con/itute ! basic gr\p ( igne\s rocks1 s call$ because !y conta9 a l>ge proportion ( ! heavi] bases1 su* z magnesia1 lime1 oxides ( iron & manganese1 c4 ,igne\s rocks v>y 9 texture f homog5e\s1 compact1 & f9ely cry/all9e masses up to co>sely cry/all9e aggregates1 9 :i* ! cry/als may be m ?an an in* 9 diamet]4 ,sometimes !y are dull & e>?y 9 texture1 at o!r times vesicul>4 ,:5 ! vesicles are fill$ up ) "s m9]al1 ! rock is said to be amygdaloidal1 f ! almond %ape assum$ by ! k]nels fill+ ! cavities4 ,:5 s+le cry/als ( any m9]al are scatt]$ ?r\gh a rock1 s z to be readily di/+ui%$ f ! compact or cry/all9e base1 ! rock becomes porphyritic4 ,,acidic ,,or ,,felspa?ic ,,gr\p4 #ca4 ,tra*yte 7tra*ys1 r\gh7 is a pale or d>k-gray rock1 h>% & r\gh to ! t\*1 9 :i* felsp> is ! pr$om9ant m9]al4 ,x is a common product ( eruption 9 mod]n volcanoes4 ,cl9k/one or phonolite is a gre5i%-gray1 compact1 felspa?ic rock1 some:at slaty or s*i/ose1 & wea!rs ) a :ite cru/4 ,x gives a cle> metallic s\nd "u ! hamm]4 ,x is a rock n met ) among ! old] =mations ( ! e>?'s cru/1 be+ conf9$ to ,t]ti>y 7see table1 p4 #he7 or /ill m rec5t times4 ,obsidian or volcanic glass is usually black1 br[n1 or gre51 & usually resembles a co>se bottle-glass4 ,:5 x becomes vesicul>1 x passes gradually into ! highly por\s rock call$ pumice4 ,x is em95tly a geologically mod]n volcanic rock4 ,fel/one is a r$di%-gray1 blui%1 gre5i%1 or yell[i%1 h>d1 compact1 fl9ty-look+ rock1 compos$ ( pota%-felsp> & silica4 ,x is g5]ally spl9t]y "u ! hamm]4 ,"s v>ieties are slaty1 & are frequ5tly mi/ak5 = cl9k/one1 :i* !y closely resemble4 ,:5 ! qu>tz 9 fel/one is di/9ctly visible ei!r z gra9s or cry/als1 ! rock passes into a qu>tz-porphyry4 ,granite is recognis$ z an igne\s z well z a metamorphic rock4 ,sometimes ! ve9s & dykes :i* proce$ f or occur ne> a mass ( granite conta9 no mica--?is k9d ( rock is call$ elvan or elvanite4 ,porphyrite or felspa?ite includes a numb] ( rocks :i* h a felspa?ic base1 ?r\gh :i* felsp> cry/als are scatt]$ m or less abundantly4 ,sometimes hornbl5de1 or augite1 or mica is pres5t4 ,! col\r is usually d>k--"s %ade ( blue1 gre51 r$1 puce1 purple1 or br[n--& ! texture v>ies f compact & f9ely cry/all9e up to co>sely cry/all9e4 ,porphyrites are usually porphyritic1 & frequ5tly amygdaloidal4 ,,augitic ,,& ,,hornbl5dic ,,or ,,basic ,,gr\p4 #cb4 ,basalt is a d>k or almo/ black compact homog5e\s rock1 compos$ ( felsp> & augite ) magnetic iron4 ,an olive-gre5 m9]al call$ oliv9e is v frequ5tly pres5t4 ,! co>s]-gra9$ basalts are call$ dol]ite4 ,! column> /ructure is n peculi>ly *>act]i/ic ( basalt4 ,_m basalts are n column>1 & n a few column> rocks are n basalts4 ,gre5/one or diorite is usually a dull gre5i% rock1 sometimes gray1 h[ev]1 speckl$ ) gre54 ,x is compos$ ( soda-felsp> & hornbl5de4 ,! f9e-gra9$ compact gre5/ones are call$ aphanite4 ,sy5ite1 l granite1 is recognis$ z an igne\s z well z a metamorphic rock4 ,!re are sev]al o!r rocks :i* come into ! basic gr\p1 b ^? m5tion$ are ! m common & typical species4 #cc4 ,fragm5tal ,igne\s ,rocks4--,all ! igne\s rocks briefly describ$ above are m or less di/9ctly cry/all9e 9 texture4 ,!re is a class ( igne\s rocks1 h[ev]1 :i* d n pres5t ?is "*1 b :5 f9e-gra9$ are dull & e>?y 9 texture1 & frequ5tly consi/ m]ely ( a rude agglom]ation ( r\gh angul> fragm5ts ( v>i\s rocks4 ,^! =m ! ,,fragm5tal gr\p ( igne\s rocks4 ,! ejectam5ta ( loose mat]ials :i* are ?r[n out dur+ a volcanic eruption1 consi/ 9 *ief measure ( fragm5ts ( lava1 c4 ( all sizes1 f m]e du/1 s&1 & grit1 up to blocks ( m ?an a ton 9 weight4 ,^! mat]ials1 z we %all aft]w>ds see1 are scatt]$ r\nd ! orifice ( eruption 9 m or less irregul> b$s4 ,! t]ms appli$ to ! v>ieties ( ejectam5ta f\nd among mod]n volcanic accumulations1 w be giv5 & expla9$ :5 we come to consid] ! nature ( geological ag5cies4 ,9 ! ,briti% ,isl&s1 & _m o!r non-volcanic regions1 we f9d besides cry/all9e igne\s rocks1 abundant traces ( loose ejectam5ta1 :i* cle>ly prove ! =m] pres5ce ( volcanoes4 ,^! mat]ials are sometimes q amorph\s--t is to say1 !y %ew no trace ( wat] action--!y h n be5 spread out 9 lay]s1 b consi/ ( rude tumultu\s accumulations ( angul> & subangul> fragm5ts ( igne\s rocks4 ,su* masses are t]m$ trappean agglom]ate & trappean breccia4 ,at o!r times1 h[ev]1 ! ejectam5ta give evid5ce ( hav+ be5 arrang$ by ! action ( wat]1 ! mat]ials hav+ be5 sift$ & spread out 9 m or less regul> lay]s4 ,:at 7 =m]ly rude breccias & agglom]ates ( angul> /ones n[ become trappean conglom]ates--! /ones hav+ be5 r\nd$ & wat]-worn--:ile ! f9e +r$i5ts1 ! grit1 & s&1 & mud1 =m ! rock call$ trap tuff4 ,fragm5tal rocks are (t5 q indurat$--! matrix be+ z h>d z ! includ$ /ones4 ,b z a rule !y are less h>d ?an cry/all9e igne\s rocks1 & 9 _m cases are loose & crumbl+4 ,:5 a fragm5tal rock is compos$ *iefly ( rocks belong+ to ! acidic gr\p1 we say x is felspa?ic4 ,:5 augitic & hornbl5dic mat]ials pr$om9ate1 !n o!r t]ms are us$2 z1 = example1 dol]ite tuff1 gre5/one tuff4 ,,/ructure ,,& ,,arrangem5t ,,( ,,rock-,,masses4 #cd4 ,! /ud5t c h>dly le>n mu* ab\t ! m9]alogical composition ( rocks1 )\t at ! same "t acquir+ "s k ( ! mann] ( _! occurr5ce 9 nature4 ,we h already briefly describ$ c]ta9 s$im5t>y rocks1 su* z conglom]ate1 s&/one1 & %ale1 & h 9 "s measure t\*$ ^u _! /ructure z rock-masses4 ,^! rocks1 z we h se51 are arrang$ 9 m or less ?ick lay]s or b$s1 :i* are pil$ "o on ! top ( ! o!r4 ,rocks :i* are s arrang$ are said to be /ratifi$1 & are t]m$ /rata4 ,we may also use ! ^w /ratum z an occasional sub/itute = b$4 ,! planes ( b$d+ or /ratification are sometimes v close toge!r1 9 o!r cases !y are wide ap>t4 ,:5 ! sep>ate b$s are v ?91 z 9 ! case ( %ale1 x is mo/ usual to t]m !m lam9ae1 & to speak ( ! lam9ation ( a %ale1 z di/+ui%$ f ! b$d+ ( a s&/one4 ,planes ( b$d+ are g5]ally m /rongly m>k$ ?an planes ( lam9ation4 ,! lam9ae frequ5tly coh]e1 :ile b$s seldom d4 ,9 ! above figure1 :i* repres5ts a v]tical cutt+ or section ?r\gh horizontal /rata1 ! planes ( lam9ation are %ewn at l1 l1 l1 & ^? ( /ratification at s1 s1 s4 ,!re are h>dly any limits to ! ?ickness ( a b$--x may range f an in* up to _m feet or y>ds1 :ile lam9ae v>y 9 ?ickness f an in* d[nw>ds4 ,illu/ration3 ,fig4 #a4--/1 s&/one1 & %1 %ale3 s1 l9es or planes ( b$d+2 l1 l9es or planes ( lam9ation4 #ce4 ,hi!rto we h be5 consid]+ ! lam9ae & /rata z ly+ 9 an approximately horizontal plane4 ,sometimes1 h[ev]1 ! lay]s ( deposition 9 a s+le /ratum are incl9$ at v>i\s angles to !mselves1 z 9 ! foll[+ figure4 ,?is /ructure is call$ false b$d+2 ! lay]s or lam9ae n co9cid+ ) ! planes ( /ratification4 ,x owes its orig9 to %ift+ curr5ts1 su* z ! ebb & fl[ ( ! tide1 & v (t5 *>act]ises deposits :i* h be5 =m$ 9 %all[ wat]4 7,hillocks ( drift+ s& frequ5tly %ew a simil> /ructure1 b _! false b$d+ is1 z a rule1 mu* m pron\nc$47 ,illu/ration3 ,fig4 #b4--;,false ,b$d+4 #cf4 ,mud-cracks & ,ra9-pr9ts4--,! surfaces ( "s b$s occasionally exhibit m>k+s closely resembl+ ^? se5 ^u a flat s&y bea* aft] ! retreat ( ! tide--h5ce !y are call$ ripple-m>ks or curr5t-m>ks4 ,!y are1 ( c\rse1 due to ! g5tle curr5t action :i* pu%es along ! gra9s ( s&1 & h5ce1 su* m>ks may be =m$ :]ev] a curr5t sweeps ov] ! bottom ( ! sea ) en]gy j suffici5t = ! purpose4 ,b s9ce ! necess>y conditions = ! =mation ( ripple-m>k occur mo/ abundantly 9 %all[ wat]1 its frequ5t appe>ance 9 a s]ies ( /rata may (t5 be tak5 z evid5ce1 s f>1 = ! %all[-wat] orig9 ( ! b$s4 ,besides ripple-m>ks we may also detect occasionally on ! surfaces ( c]ta9 /rata mud-cracks & ra9-pr9ts4 ,^! occur mo/ commonly 9 f9e-gra9$ b$s1 z 9 flag/ones1 argillace\s s&/ones1 %ales1 c4 ,! mud-cracks resemble ^? ^u a mud-flat :i* are caus$ by ! desiccation & consequ5t %r9kage ( ! mud :5 expos$ to ! sun4 ,! old cracks h be5 subsequ5tly fill$ up aga9 by a deposition ( mud or s&1 usually ( h>d] consi/5cy ?an ! rock trav]s$ by ! cracks4 ,h5ce1 :5 ! b$ t ov]lies ! mud-cracks is remov$1 we f9d a ca/ ( ^! project+ f its "u surface1 or frequ5tly ! ca/ rema9s 9 its m\ld1 & =ms a s]ies ( curi\s ridges ramify+ ov] ! :ole surface ( ! old mud-flat4 ,ra9-pr9ts are ! small pits caus$ by ! impact ( l>ge drops4 ,!y are usually deep] at "o side ?an ! o!r1 f :i* we c inf] ! direction ( ! w9d at ! "t ! ra9-drops fell4 ,l ! mud-cracks1 !y are mo/ commonly met ) 9 f9e-gra9$ b$s1 & h be5 pres]v$ 9 a simil> mann]4 ,"s geologi/s h also be5 able to detect wave-m>ks1 'fa9t outl9+s ( curv$ =m on a s&/one lay]1 l ! outl9e left by a wave along ! limit :]e x dies out ^u a bea*4' #cg4 ,succession ( ,/rata4--,! succession ( /rata is (t5 v div]sifi$4 ,?us1 we may obs]ve 9 "o & ! same section numb]less alt]nat+ b$s ( s&/one & %ale f an in* or s up to sev]al feet ea* 9 ?ickness1 ) seams ( coal1 fireclay1 iron/one1 & lime/one int]/ratifi$ among !m4 ,9 o!r cases1 aga91 ! succession is simpl]1 & "s deep qu>ries %ew only "o b$1 z is ! case ) c]ta9 lime/ones1 f9e-gra9$ s&/ones 7liv]-rock71 & _m volcanic rocks4 ,"s lime/ones1 inde$1 %ew small trace ( b$d+ ?r\gh\t a v]tical ?ickness ( hundr$s ( feet4 #ch4 ,b$s1 _! ,ext5t1 c4--,b$s ( rock are n only ( v diff]5t ?icknesses1 b !y are also ( v v>iable ext5t4 ,"s may ?9 gradually away1 or 'die out' sudd5ly1 9 a few feet or y>ds1 :ile o!rs may ext5d ov] _m squ>e miles4 ,b$s ( lime/one1 = example1 c (t5 be trac$ = leagues 9 sev]al directions2 & if ?is be ! case ) c]ta9 s+le b$s1 x is /ill m true ( gr\ps ( /rata4 ,?us ! coal-be>+ /rata belong+ to :at is call$ ! ,c>bonif]\s p]iod cov] l>ge areas 9 ,wales1 ,engl&1 ,scotl&1 & ,irel&1 n less1 probably1 ?an #fjjj squ>e miles2 & /rata belong+ to ! same great p]iod spread ov] consid]able tracts on ! ,cont95t1 & a v ext5sive area 9 ,nor? ,am]ica4 ,x holds g5]ally true t b$s ( f9e-gra9$ mat]ials are n only ( m equal ?ickness ?r\gh\t1 b h also a wid] ext5sion ?an co>s]-gra9$ rocks4 ,f9e s&/ones1 = example1 ext5d ov] a wid] area1 & pres]ve a m equable ?ickness ?r\gh\t ?an conglom]ates1 :ile lime/ones & coals are m cont9u\s ?an ei!r4 #ci4 ,:5 a b$ is foll[$ = any di/ance x is frequ5tly f\nd to ?9 away1 & give place to ano!r occupy+ ! same plane or horizon4 ,?us a %ale w be replac$ by a s&/one1 a s&/one by a conglom]ate1 & vice v]sa4 ,sometimes also we may f9d a %ale1 z we trace x 9 "s p>ticul> direction1 gradually becom+ *>g$ ) calc>e\s matt]1 s z by & by to pass1 z x 71 into lime/one4 ,e b$ mu/1 ( c\rse1 end some:]e1 ei!r by ?us gradually pass+ into ano!r1 or by ?9n+ out s z to all[ b$s :i* imm$iately ov]lie & und]lie x to come toge!r4 ,n unfrequ5tly1 h[ev]1 a b$ w /op abruptly1 z 9 fig4 #c4 ,illu/ration3 ,fig4 #c4--,sudd5 end+ ( ,b$ at x4 #dj4 ,sequ5ce ( ,b$s4--,x requires little reflection to see t ! division plane betwe5 two b$s may repres5t a v long p]iod ( "t4 ,let ! foll[+ diagram repres5t a section ( /rata1 s be+ b$s ( grit1 & a1 b1 c1 b$s ( s&/one & %ale4 ,x is evid5t t ! b$s s mu/ h be5 =m$ be=e ! /rata b 7 deposit$ above !m4 ,at x1 ! b$s a & b come toge!r1 & 7 att5tion to be conf9$ to t "p ( ! section1 ! obs]v] might be l$ to inf] t no great space ( "t elaps$ betwe5 ! deposition ( ^! two b$s4 ,yet we see t an int]val suffici5t to all[ ( ! =mation ( ! b$s s mu/ really h int]v5$4 ,x is n[ well kn[n t 9 _m cases planes ( b$d+ repres5t 'breaks 9 ! succession' ( /rata--'breaks' :i* are (t5 ! equival5ts ( consid]able ?icknesses ( /rata4 ,9 "o place1 = example1 we may h an app>5tly complete sequ5ce ( b$s1 z a1 b1 c1 :i* a m ext5d$ k ( ! same b$s1 z ^! are develop$ 9 "s o!r locality1 enables u to supplem5t1 z a1 s1 b1 c4 ,illu/ration3 ,fig4 #d4--,sequ5ce ( ,b$s4 #da4 ,jo9ts4--,besides planes or l9es ( b$d+1 !re are c]ta9 o!r division planes or jo9ts by :i* rocks are int]sect$4 ,! =m]1 z we h se51 are cong5ital2 ! latt] are subsequ5t4 ,jo9ts cut "r across ! b$d+1 & are (t5 v>i\sly comb9$1 "o set ( jo9t planes trav]s+ ! rock 9 "o direction1 & ano!r set or sets int]sect+ ^! at v>i\s angles4 ,?us1 9 _m cases ! rocks are s divid$ z easily to sep>ate into m or less irregul> fragm5ts ( v>i\s sizes4 ,besides ^! confus$ jo9ts !re are usually o!r m regul> division planes1 :i* int]sect ! /rata 9 "s def9ite directions1 & run p>allel to ea* o!r1 (t5 ov] a wide area3 ^! are call$ ma/]-jo9ts4 ,two sets ( ma/]-jo9ts may int]sect ! same /rata1 & :5 su* is ! case1 ! rock may be qu>ri$ 9 cuboidal blocks1 ! size ( :i* w v>y1 ( c\rse1 accord+ z ! two sets ( jo9ts are ne> or wide ap>t4 ,jo9ts may ei!r gape or be q close2 s close1 inde$1 z 9 _m cases to be invisible to ! nak$ eye4 ,c]ta9 igne\s rocks frequ5tly %ew division planes :i* meet ea* o!r 9 su* a way z to =m a s]ies ( polygonal prisms4 ,! basalt ( ,/affa & ,giants' ,causeway are famili> examples ( ?is /ructure4 ,jo9t+ is due to ! gradual consolidation ( ! /rata1 & h5ce1 9 a s]ies ( /rata1 we may f9d ! sep>ate b$s1 accord+ to _! composition1 v v>i\sly affect$1 "s be+ mu* m abundantly jo9t$ ?an o!rs4 ,ma/]-jo9ts :i* trav]se a wide di/rict 9 "s def9ite direction probably owe _! orig9 to t5sion1 ! /rata hav+ be5 subject$ to "s /ra9 by ! und]gr\nd =ces4 ,illu/ration3 ,fig4 #e4--;,b$s ( ,lime/one 7a71 ,s&/one 7b71 & ,%ale 7c71 divid$ into cuboidal masses by ma/]-jo9ts4 ,illu/ration3 ,fig4 #f4--;,column> ,/ructure4 ,illu/ration3 ,fig4 #g4--;,b$d+1 ,jo9ts1 & ,cleavage 7aft] ,mur*ison74 #db4 ,cleavage4--,f9e-gra9$ rocks1 m especially ^? :i* are argillace\s1 occasionally %ew ano!r k9d ( /ructure1 :i* is call$ cleavage4 ,common clay-slate is a type ( ! /ructure4 ,?is rock splits up into innum]able ?9 lam9ae or plates1 ! surface ( :i* may ei!r be some:at r\gh1 or z smoo? ne>ly z glass4 ,! cleavage planes1 h[ev]1 ne$ n be p>allel ) ! planes ( b$d+2 9 mo/ cases1 inde$1 !y cut "r across ^!1 & cont9ue p>allel to ea* o!r (t5 ov] a v wide region4 ,! orig9al b$d+ is sometimes entirely oblit]at$1 & 9 mo/ cases ( well-def9$ cleavage is always m or less obscure4 ,9 ! prec$+ diagram1 ! g5]al ph5om5a ( b$d+1 jo9t+1 & cleavage are repres5t$4 ,! l9es ( b$d+ are %ewn at ,s1 ,s2 ano!r set ( division-planes 7jo9ts7 is obs]v$ at ,j1 ,j1 int]sect+ ! =m] at "r angles--,a1 ,b1 ,c be+ ! expos$ faces ( jo9ts4 ,! l9es ( cleavage are se5 at ,d1 ,d1 cutt+ across ! planes ( b$d+ & jo9t+4 #dc4 ,foliation is ano!r k9d ( sup]9duc$ /ructure4 ,9 a foliat$ rock ! m9]al +r$i5ts h be5 cry/allis$ & arrang$ 9 lay]s along ei!r ! planes ( orig9al b$d+ or ^? ( cleavage4 ,mica-s*i/ & gneiss are typical examples4 #dd4 ,concretions4--,9 _m rocks a concretion>y /ructure may be obs]v$4 ,"s s&/ones & %ales appe> z if made up ( sph]oidal masses1 ! m9]al composition ( ! sph]oids n diff]+ app>5tly f t ( ! un*ang$ rock4 ,s 9 "s k9ds ( lime/one1 z 9 dolomite1 ! concretion>y /ructure is (t5 highly develop$1 ! rock resembl+ n[ irregul> heaps ( turnips ) f+]-&-toe disease1 aga91 piles ( cannon-balls1 or bun*es ( grapes1 & agglom]ations ( musket-%ot4 ,a sph]oidal /ructure is occasionally met ) among/ "s igne\s rocks4 ,?is is well se5 9 ! case ( rocks hav+ ! basaltic /ructure1 9 :i* ! pill>s1 be+ jo9t$ transv]sely1 decompose along _! division planes1 s z to =m irregul> globul> masses4 ,9 _m cases1 c]ta9 m9]al matt] :i* 0 orig9ally diffus$ ?r\gh a rock has segregat$ s z to =m nodules & irregul> lay]s4 ,examples ( ?is are *]t nodules 9 lime/one2 fl9t nodules 9 *alk2 clay-iron/one balls 9 %ale1 c4 ,illu/ration3 ,fig4 #h4--;,dip & ,/rike ( ,/rata4 #de4 ,incl9ation ( ,/rata4--,b$s ( aque\s /rata mu/ h be5 deposit$ 9 horizontal or approximately horizontal planes2 b we n[ f9d !m mo/ frequ5tly incl9$ at v>i\s angles to ! horizon1 & (t5 ev5 /&+ on end4 ,!y sometimes1 h[ev]1 reta9 a horizontal position ov] a l>ge tract ( c\ntry4 ,! angle :i* ! incl9$ /rata make ) ! horizon is call$ ! dip1 ! degree ( incl9ation be+ ! am\nt ( ! dip2 & a l9e drawn at "r angles to ! dip is call$ ! /rike ( ! b$s4 ,?us1 a b$ dipp+ s\?-we/ w h a nor?-we/ & s\?-ea/ /rike4 ,! crop or outcrop 7sometimes also1 b r>ely1 call$ ! basset edge7 ( a b$ is ! place :]e ! edge ( ! /ratum comes to view at ! surface4 ,we may look ^u incl9$ b$s z be+ m]ely p>ts ( m or less ext5sive undulations ( /rata1 ! tops ( ! undulations hav+ be5 remov$ s z to expose ! truncat$ edges ( ! b$s4 ,9 ! foll[+ diagram1 = example1 ! outcrops ( lime/one se5 at l1 l1 are evid5tly portions ( "o & ! same /ratum1 ! dott$ l9es indicat+ its =m] ext5t4 ,! tr\gh-%ap$ arrangem5t ( ! b$s at s is call$ a syncl9al curve1 or simply a syncl9e2 ! ar*$ /rata at a =m+1 on ! contr>y1 an anticl9al curve or anticl9e4 ,illu/ration3 ,fig4 #i4--;,anticl9es & ,syncl9es4 ,illu/ration3 ,fig4 #aj4--;,contort$ ,/rata4 ,:5 /rata %ew _m & rapid curves1 !y are said to be contort$4 ,! diagram section 7fig4 #aj7 w be/ expla9 :at is meant by ?is k9d ( /ructure4 #df4 ,9 c]ta9 regions1 ! /rata (t5 dip 9 "o & ! same direction = _m miles1 at an angle approa*+ v]ticality1 z 9 ! foll[+ section4 ,x might be inf]r$1 !re=e1 t f ,a to ,b we _h a gradually asc5d+ s]ies--t z we pac$ ov] ! outcrop we 7 /epp+ con/antly f a l[] to a high] geological horizon4 ,b1 9 su* cases1 ! dip is deceptive1 ! same b$s be+ repeat$ aga9 & aga9 9 a s]ies ( great fold+s ( ! /rata4 ,su* is ! case ov] wide areas 9 ! upl& di/ricts ( ! s\? ( ,scotl&4 ,! section 7fig4 #aa7 %ews t ! b$s are actually inv]t$1 ! /rata at x x be+ b5t back ^u /rata :i* really ov]lie !m4 ,illu/ration3 ,fig4 #aa4--;,inv]sion ( ,/rata4 ,illu/ration3 ,fig4 #ab4--;,contemporane\s ,erosion4 #dg4 ,contemporane\s ,erosion4--,occasionally a gr\p ( /rata gives pro( t pauses 9 ! deposition ( s$im5t took place1 dur+ :i* runn+ wat] scoop$ out ( ! s$im5t *annels ( great] or less wid?1 :i* subsequ5tly became fill$ up ) simil> or dissimil> mat]ials4 ,! diagram 7fig4 #ab7 w r5d] ?is pla94 ,at a we h b$s ( s&/one1 :i* x is evid5t 7 at "o "t ?r\gh\t z ?ick z !y /ill are at x x4 ,hav+ be5 worn away to ! ext5t indicat$1 a deposition ( clay 7b7 succe$$2 & ?is1 9 turn1 became erod$ at c1 c1 ! holl[s be+ fill$ up aga9 ) co>se s& & gravel4 ,9 =m] p>agraphs1 we f\nd reason to believe t l9es ( b$d+ indicat$ c]ta9 pauses 9 ! deposition ( /rata4 ,"h1 9 ! pres5t case1 we h m ample pro( 9 ! same direction4 ,illu/ration3 ,fig4 #ac4--,uncon=mability4 #dh4 ,uncon=mability4--,b ! mo/ /rik+ evid5ce ( su* pauses 9 ! deposition ( /rata is af=d$ by ! ph5om5on call$ uncon=mability4 ,:5 "o set ( rocks is f\nd re/+ on ! upturn$ edges ( a l[] set1 ! =m] are said to be uncon=mable to ! latt]4 ,9 ! above section 7fig4 #ac71 a1 a1 are b$s ( s&/one re/+ on ! upturn$ edges ( b$s ( lime/one1 %ale1 & s&/one1 l1 s4 ,figs4 #ad & #ae give o!r examples ( ! same appe>ance4 ,x is evid5t t1 9 ! case ( fig4 #ad1 ! discordant b$d+ *ronicles ! lapse ( a v long p]iod4 ,we h to conceive fir/ ( ! deposition ( ! und]ly+ /rata 9 horizontal or approximately horizontal lay]s2 !n we h to ?9k ( ! "t :5 !y 7 crumpl$ up into great convolutions1 & ! tops ( ! convolutions 7! anticl9es7 7 plan$ away3 all ^! *anges int]v5$1 ( c\rse1 aft] ! l[] set 0 deposit$1 & be=e ! upp] s]ies 0 laid d[n4 ,9 ! case repres5t$ 9 fig4 #ae1 we h a d\ble uncon=mability1 imply+ a /ill m elaborate s]ies ( *anges1 & probably1 !re=e1 a /ill long] lapse ( "t4 ,illu/ration3 ,fig4 #ad4--,viol5t ,uncon=mability4 ,illu/ration3 ,fig4 #ae4--;,d\ble ,uncon=mability4 #di4 ,ov]lap4--,:5 ! upp] b$s ( a con=mable gr\p ( /rata spread ov] a wid] area ?an ! l[] memb]s ( ! same s]ies1 !y are said to ov]lap4 ,! accompany+ diagram %ews ?is appe>ance4 ,an ov]lap proves t a gradual subm]g5ce ( ! l& 0 go+ on at ! "t ! /rata 7 be+ accumulat$4 ,z ! l& disappe>$ bel[ ! wat]1 ! s$im5t gradually spread ov] a wid] area1 ! m rec5tly deposit$ s$im5t be+ laid d[n 9 places :i* exi/$ z dry l& at ! "t :5 ! e>lie/ accumulations 7 =m$4 ,?us1 9 ! accompany+ illu/ration 7fig4 #af71 ! /ratum m>k$ #a1 re/+ uncon=mably ^u old] /rata1 is ov]lapp$ by #b1 z t is by #c1 & s on--all ! b$s 9 succession com+ to repose ^u ! old] /rata at high] & high] levels1 z ! old l& subsid$4 ,illu/ration3 ,fig4 #af4--,ov]lap4 ,illu/ration3 ,fig4 #ag4--;,fault4 #ej4 ,dislocations or ,faults4--,:5 /rata1 once cont9u\s1 h be5 brok5 across1 & displac$ or %ift$ along ! l9e ( breakage1 !y are said to be fault$1 ! fissure along :i* ! displacem5t occurs be+ t]m$ a fault or dislocation4 ,! simple/ =m ( a fault is t %ewn 9 ! foll[+ diagram1 :]e /rata ( s&/one & %ale1 ) a coal-seam1 ,s1 h be5 %ift$ along ! l9e f4 ,! direction 9 :i* ! fault is incl9$,d is its hade1 & ! degree ( v]tical displacem5t ( ! b$s is ! am\nt ( ! dislocation4 ,g5]ally1 ! b$s seem to be pull$ d[n 9 ! direction ( ! d[n?r[1 & drawn up on ! opposite side ( ! fault1 z %ewn 9 ! diagram4 ,sometimes ! rocks on ea* side ( a fault are smoo!d & poli%$1 & cov]$ ) long scrat*es1 z if ! two sides ( ! fissure _h be5 rubb$ toge!r4 ,?is is ! appe>ance call$ slick5sides4 ,slick5sides1 h[ev]1 may occur on ! walls ( a fissure :i* is n a displacem5t1 b a m]e jo9t or crack4 ,a dislocation is spok5 ( z a d[n?r[ or an upca/1 accord+ to ! direction 9 :i* x is approa*$4 ,?us1 a m9] work+ along ! coal-seam ,s1 f a to b1 w\ld describe ! fault1 f1 z an upca/1 s9ce he w\ld h to m9e to a high] level to cat* 8 coal aga94 ,b1 _h he approa*$ ! fault f c to d1 he w\ld !n h t]m$ x a d[n?r[1 because he w\ld see f ! hade ( ! fault t 8 coal-seam mu/ be s\ght = at a l[] level4 ,faults are ( all sizes1 f a foot or two up to v]tical displacem5ts ( ?\s&s ( feet4 ,p[]ful dislocations c (t5 be foll[$ = _m miles across a c\ntry1 runn+ 9 a m or less l9e> direction4 ,?us1 "o l>ge fault has be5 trac$ across ! bread? ( ,scotl&1 f ne> ,/ ,abb's ,head1 9 ! ea/1 to ! coa/ ( ,wigt[n1 9 ! we/4 ,e l>ge ?r[ is accompani$ by a numb] ( small] ones--"s ( :i* run p>allel to ! ma9 fault1 :ile _m o!rs seem to run out f ?is at v>i\s angles4 ,faults are ( all geological ages4 ,"s date back to a mo/ remote antiquity1 o!rs are ( q rec5t orig92 & no d\bt faults are occurr+ ev5 n[4 ,9 ! foll[+ diagram1 ! /rata1 a1 a1 h be5 fault$ & plan$ away be=e ! /rata1 b1 7 deposit$4 ,h5ce1 9 ?is case1 x is evid5t t if we "k ! geological age ( ! b$s1 a & b1 we c h an approximation to ! age ( ! fault4 ,if ! b$s1 a1 be ,c>bonif]\s1 & ^? at b ,p]mian1 !n we %\ld say ! fault 0 po/-,c>bonif]\s or pre-,p]mian4 ,d ,! degree ( incl9ation is v v>iable4 ,x may occur at almo/ any angle up to v]tical4 ,b1 z a rule1 ! hade ( ! m p[]ful faults is /eep] ?an t ( m9or displacem5ts4 ,illu/ration3 ,fig4 #ah4--;,gr\nd-plan ( ,l>ge ,ma9 ,fault & ,m9or ,displacem5t ,fissures4 ,illu/ration3 ,fig4 #ai4--;,fault$ ,/rata cov]$ by undi/urb$ ,/rata4 #ea4 ,metamorphic & ,igne\s ,rocks--mode ( _! occurr5ce4--,9 ! =ego+ rem>ks on ! /ructure & arrangem5t ( rocks we h _h ref]5ce *iefly to ! aque\s /rata--t is to say1 ! me*anically1 *emically1 & organically =m$ rocks4 ,we 7 necess>ily compell$1 h[ev]1 to make "s ref]5ce to1 & to give "s description (1 c]ta9 /ructures & arrangem5ts :i* are n peculi> to aque\s /rata1 b *>act]ise _m metamorphic & igne\s rocks z well4 ,to avoid repetition x 0 also necess>y1 :ile treat+ ( jo9ts1 c41 to give "s acc\nt ( c]ta9 /ructures :i* are ! result ( metamorphic action4 ,b1 = sake ( cle>ness1 we h res]v$ special acc\nt ( ! /ructure & mode ( occurr5ce ( metamorphic & igne\s rocks to ?is place4 ,aft] :at has be5 said z to ! /ructure & arrangem5t ( aque\s /rata1 x is h>dly ne$ful to say mu* ab\t ! cry/all9e s*i/s4 ,^! ! /ud5t w und]/& to be m]ely highly alt]$ aque\s rocks1,e 9 :i* ! m>ks ( _! orig9 are /ill m or less di/9ctly traceable4 ,z a rule1 metamorphic /rata are contort$1 twi/$1 & crumpl$1 al?\gh "h & !re comp>atively horizontal /ret*es ( alt]$ rocks may be obs]v$4 ,! regions 9 :i* !y occur are (t5 hilly & m\nta9\s1 b ?is is by no means inv>iably ! case4 ,! great] "p ( ! m\nta9\s regions ( ! ,briti% ,isl&s is occupi$ by rocks :i* are m or less alt]$2 ! m cry/all9e rocks1 su* z mica-s*i/1 gneiss1 c41 be+ abundantly develop$ 9 ! ,scotti% ,highl&s1 & 9 ! nor? & we/ ( ,irel&2 :ile ^? :i* are less alt]$ cov] l>ge areas 9 ! s\? ( ,scotl&1 & 9 ,wales & ! nor?-we/ ( ,engl&4 ,?r\gh\t ^! wide areas ! rocks g5]ally dip at high angles1 & contortion & crumpl+ are ( common occurr5ce4 ,! f9]-gra9$ clay-rocks also exhibit f9e cleavage planes1 & are 9 "s places qu>ri$ = ro(+-slates--! ,wel% qu>ries be+ ! mo/ fam\s4 ,"h & !re1 b$d+ is entirely effac$1 & ! result+ rock is q amorph\s1 &1 becom+ gradually m & m cry/all9e1 passes at la/ into a rock :i* 9 _m cases is true granite4 ,! orig9al /rata h disappe>$1 & granite occupies _! place1 9 su* a way z to lead to ! inf]5ce t ! granite is m]ely ! aque\s /rata :i* h be5 fus$ up1 z x 71 9 situ4 ,at o!r times ! granite w\ld appe> to h be5 erupt$ among/ ! aque\s /rata1 = ^! are highly confus$1 & bak$1 z x 71 at _! junction ) ! granite1 f :i*1 also1 long ve9s are se5 protrud+ into ! surr\nd+ b$s4 ,metamorphic granite1 !n1 graduates1 z a rule1 almo/ imp]ceptibly into rocks :i* are cle>ly ( aque\s orig92 :ile on ! contr>y ! junction-l9e betwe5 igne\s granite & ! surr\nd+ rocks is always well m>k$4 ,! orig9 ( granite1 h[ev]1 is a difficult "q1 & "o :i* has giv5 rise to mu* discussion4 ,"s fur!r rem>ks ^u ! subject w be f\nd 9 ! sequel "u ! head+ ( ,metamorphism4 ,e ,igne\s rocks h also 9 "s cases und]gone consid]able alt]ation2 f9e-gra9$ tuffs1 = example1 occasionally assume a cry/all9e texture4 #eb4 ,true igne\s rocks occur ei!r 9 b$s or z irregul> amorph\s masses4 ,:5 !y occur z b$s int]/ratifi$ ) aque\s /rata1 !y are said to be contemporane\s1 because !y h evid5tly be5 erupt$ at ! "t ! s]ies ( /rata among :i* !y appe> 0 be+ amass$4 ,:51 on ! o!r h&1 !y cut across ! b$d+1 !y are said to be subsequ5t or intrusive1 because 9 ?is case !y h be5 =m$ at a p]iod subsequ5t to ! /rata among :i* !y h be5 intrud$4 ,! b$ ^u :i* a contemporane\s igne\s rock recl9es1 (t5 af=ds m>ks ( hav+ be5 subject$ to ! action ( heat2 s&/ones be+ h>d5$1 & frequ5tly mu* jo9t$ & crack$1 ow+ to ! %r9k+ induc$ by ! heat ( ! once molt5 rock above1 & clay-rocks (t5 assum+ a bak$ appe>ance4 ,!re is g5]ally1 also1 "s discoloration bo? 9 ! pavem5t ( rock ^u :i* ! igne\s mass lies1 & 9 ! "u portions ( ! latt] itself4 ,! b$s ov]ly+ a contemporane\s igne\s rock1 h[ev]1 d n exhibit any m>ks ( ! action ( heat2 ! old lava-/ream hav+ cool$ be=e ! s$im5t1 n[ =m+ ! ov]ly+ /rata1 0 accumulat$ ov] its surface4 ,"o may (t5 notice h[ ! s& & mud h quietly settl$ d[n into ! irregul> holl[s & crevices ( ! old lava1 z 9 ! foll[+ section1 :]e i repres5ts ! igne\s rock2 a be+ ! bak$ pavem5t ( s&/one1 c42 & b ! ov]ly+ s$im5t>y deposits4 ,:5 ! igne\s rock itself is exam9$1 its upp] portions are (t5 obs]v$ to be scoriace\s or c9d]-l1 & ! "u portions likewise frequ5tly exhibit a simil> appe>ance4 ,x is g5]ally mo/ solid t[>ds ! c5tre ( ! b$4 ,! vesicles1 or pores1 9 ! upp] & l[] portions are (t5 flatt5$1 & are frequ5tly fill$ ) m9]al matt]4 ,sometimes ^! cavities may h be5 fill$ at ! "t ! rock 0 be+ erupt$1 b 9 mo/ cases ! m9]al matt] w\ld appe> to h be5 introduc$ subsequ5tly by ! action ( wat] p]colat+ ?r\gh ! rock4 ,occasionally we meet ) igne\s rocks :i* are m or less vesicul> & amygdaloidal ?r\gh\t _! entire mass4 ,o!rs1 aga91 (t5 %ew no vesicul> /ructure1 b are homog5e\s f top to bottom4 ,! texture is also v v>iable1 & ?is ev5 9 ! same rock-mass2 "s portions be+ compact or f9e-gra9$1 & o!rs co>sely cry/all9e4 ,z a rule ! rock is mo/ cry/all9e t[>ds ! c5tre1 & gets f9]-gra9$ z ! top & bottom ( ! b$ are approa*$4 ,n unfrequ5tly1 h[ev]1 an igne\s rock w pres]ve ! same texture ?r\gh\t4 ,! jo9t+ is also highly irregul> z a rule4 ,b 9 _m cases1 especially :5 ! rock is f9e-gra9$1 ! jo9t+ is v regul>4 ,! basaltic columns ( ! ,giants' ,causeway & ! ,isle ( ,/affa are well-kn[n examples ( su* regul>ly jo9t$ masses4 ,igne\s rocks frequ5tly decompose into a loose e>?y mass 7wacke71 & ?is is mo/ m>k$ly ! case ) ^? belong+ to ! basic gr\p4 ,illu/ration3 ,fig4 #bj4--;,contemporane\s ,igne\s ,rock4 #ec4 ,contemporane\s igne\s rocks are frequ5tly associat$ ) m or less regul> b$s ( breccia1 conglom]ate1 a%1 tuff1 c4 ,^! are evid5tly ! loose volcanic ejectam5ta :i* accompani$ =m] eruptions ( lava1 & h be5 arrang$ by ! action ( wat]4 ,b$s ( su* mat]ials1 h[ev]1 frequ5tly occur )\t any accompany+ lava-=m rocks4 ,nor are !y always arrang$ 9 b$d$ masses4 ,!y sometimes appe> fill+ v]tical pipes :i* seem to h be5 ! funnels ( old volcanoes4 ,! foll[+ section exhibits ! g5]al appe>ance ( "o ( ^! volcanic necks4 ,!y are v common 9 "s p>ts ( ,scotl&1 z 9 ,ayr%ire1 & are frequ5tly rang$ along ! l9e ( a fault 9 ! /rata4 ,fig4 #ba %ews su* a neck ( ejectam5ta1 made up ( fragm5ts ( v>i\s k9ds ( rock1 su* z s&/one1 %ale1 lime/one1 coal1 c41 sometimes )\t any admixture ( igne\s rocks4 ,! /rata ?r\gh :i* ! pipe has be5 pi]c$ usually dip 9 t[>ds ! latt]1 & at _! junction ) ! co>se agglom]ate (t5 %ew m>ks ( ! action ( heat1 coal-seams hav+ sometimes be5 'burn$' useless = a numb] ( y>ds away f ! 'neck4' ,illu/ration3 ,fig4 #ba4--,neck fill$ ) ,volcanic ,agglom]ate4 #ed4 ,intrusive igne\s rocks occur z %eets1 dykes1 & necks4 ,! %eets frequ5tly con=m = long di/ances to ! b$d+ ( ! /rata among :i* !y occur1 & are ?us liable to be mi/ak5 = contemporane\s rocks4 ,b :5 !y are closely exam9$1 x w be se5 t !y n only bake or alt] ! b$s above & bel[ !m1 b seldom keep precisely to "o horizon or level--occasionally ris+ to a high]1 or s9k+ to a l[] position 9 ! /rata1 z %ewn 9 ! foll[+ diagram-section4 ,dykes are wall-l masses ( igne\s /rata :i* cut across ! /rata1 g5]ally at a high angle 7see d1 d1 fig4 #bb74 ,9 ! neighb\rhood ( a rec5t volcanic orifice1 num]\s dykes are se5 ramify+ 9 all directions4 ,9 ! ,briti% ,isl&s "s dykes h be5 foll[$ 9 a l9e> direction = v long di/ances4 ,sometimes ^! occupy ! sites ( l>ge dislocations1 at o!r times !y h cut ?r\gh ! /rata )\t displac+ !m4 ,occasionally !y appe> to h be5 ! fe$]s ( ! great %eets ( igne\s rock :i* "h & !re occur 9 _! vic9ity4 ,! ph5om5a pres5t$ by ! necks ( intrusive rock d n diff] f ^? *>act]i/ic ( agglom]ate or tuff necks4 ,! /rata are b5t d[n t[>ds ! c5tral plug ( igne\s rock1 & are g5]ally m or less alt]$ at ! l9e ( junction4 ,illu/ration3 ,fig4 #bb4--;,intrusive ,%eet & ,dykes3 i1 igne\s intrusive %eet2 d1 d1 dykes2 s1 s1 s$im5t>y /rata4 #ee4 ,intrusive rocks (f]1 z a rule1 "s contra/s 9 texture to contemporane\s masses4 ,!y are seldom amygdaloidal1 b :5 !y are s x is g5]ally t[>ds ! c5tre ( ! mass4 ,! k]nels are usually m9ute & m or less sph]ical4 ,illu/ration3 ,fig4 #bc4--;,contemporane\s & ,intrusive ,igne\s ,rocks3 c1 c1 contemporane\s trap-rocks#a2 t1 t1 contemporane\s fragm5tal igne\s rocks2 i1 p1 n1 d1 intrusive igne\s rocks4 ,! diagram 7fig4 #bc7 %ews ! g5]al mode ( occurr5ce ( igne\s rocks on ! l>ge scale4 ,! /ratifi$ aque\s deposits are indicat$ at a1 a4 ,^! are ov]laid by a s]ies ( alt]nat+ b$s ( cry/all9e 7c7 & fragm5tal 7t7 igne\s rocks4 ,an irregul> intrusive %eet at i cuts across ! b$s a1 a4 ,at p1 ano!r intrusive mass is se5 ris+ 9 a pipe1 z x 71 & ov]fl[+ ! b$s a1 a1 s z to =m a cap4 ,a volcanic neck fill$ ) angul> /ones int]sects ! /rata at n1 & two dykes1 approa*+ ! v]tical1 trav]se ! b$d$ rocks at d1 d4 ,x w be notic$ t ! contemporane\s igne\s rocks =m a s]ies ( esc>pm5ts ris+ "o above ! o!r4 ,! alt]ation effect$ by igne\s rocks is g5]ally greate/ 9 ! case ( intrusive masses4 ,?is is well se5 9 "s ( our coal-fields1 :]e ! coal has frequ5tly be5 de/roy$ ov] l>ge areas by ! proximity ( masses ( :at 0 once melt$ rock4 ,x is curi\s to notice h[ ! intrusive %eets 9 a great s]ies ( /rata h =c$ _! way along ! l9es ( lea/ resi/ance4 ,?us1 9 ! ,scotti% coal-fields1 we f9d aga9 & aga9 t intrusive %eets h be5 squirt$ along ! planes occupi$ by coal-seams1 ^! hav+ be5 m easily attack$ ?an b$s ( s&/one or %ale4 ,! coal 9 su* cases is ei!r entirely 'eat5 up1' z x 71 or conv]t$ into a black soot4 ,at o!r times1 h[ev]1 x is *ang$ into a k9d ( coke1 :ile o!r seams at a great] di/ance f ! intrusive mass h be5 alt]$ into a k9d ( 'bl9d coal' or an?racite4 ,^! rem>ks on ! mode ( occurr5ce ( igne\s rocks are meant to ref] *iefly to ^? masses :i* occur 9 regions :]e volcanic action has long be5 ext9ct1 z1 = in/ance1 9 ! ,briti% ,isl&s4 ,9 ! sequel1 "s acc\nt w be giv5 ( ! appe>ances pres5t$ by mod]n volcanoes & volcanic rocks4 #a ,x has be5 usual to apply ! t]m trap or trappean rock to all ! old igne\s rocks :i* c\ld nei!r be class$ ) ! granites & sy5ites1 nor yet ) ! rec5t lavas1 c41 :i* are connect$ ) a m or less well-m>k$ volcanic v5t4 ,! t]m trap 7,sw$i% trappa1 a flight ( /eps7 0 sugge/$ by ! t]rac$ or /ep-l appe>ance pres5t$ by hills :i* are built up ( successive b$s ( igne\s rock4 ,b ! passage f ! granitic into ! s-call$ trap rocks1 & f ^! into ! di/9ctly volcanic1 is s v gradual1 t x is impossible to say :]e ! "o class ends & ! o!r beg9s4 ,! t]m trap1 !re=e1 has no sci5tific precision1 al?\gh x is sometimes v conv5i5t z a k9d ( broad g5]ic t]m to include a l>ge numb] ( rocks4 ,,m9]al ,,ve9s4 #ef4 ,! cracks & crevices & jo9t planes :i* int]sect all rocks 9 a great] or less degree1 are n unfrequ5tly fill$ ) subsequ5tly introduc$ m9]al matt]1 =m+ :at are t]m$ ve9s4 ,?is introduc$ matt] may ei!r be h>d] or less durable ?an ! rock itself2 9 ! =m] case1 ! ve9s w project f ! surface ( ! /one1 :]e t has be5 subject$ to ! wea!r+ action ( ! atmosph]e2 9 ! latt] case1 ! ve9s1 "u l circum/ances1 are (t5 p>tially empti$ ( _! m9]al matt]4 ,n unfrequ5tly1 h[ev]1 ! m or less irregul>ly ramify+1 non-metallif]\s ve9s appe> z if !y _h segregat$ f ! body ( ! rock 9 :i* !y occur1 z 9 ! case ( ! qu>tz ve9s 9 granite4 ,besides ^! irregul> ve9s1 ! rocks ( c]ta9 di/ricts are trav]s$ 9 "o or m det]m9ate directions by fissures1 ext5d+ f ! surface d[n to unkn[n dep?s4 ,^! great fissures are (t5 9 l mann] fill$ ) m9]al matt]4 ,! m9]als are usually arrang$ 9 b&s or lay]s :i* run p>allel to ! walls ( ! ve94 ,qu>tz1 fluor-sp>1 b>ytes1 calcite1 c4 are among ! commone/ ve9-m9]als1 & ) ^! are frequ5tly associat$ ores ( v>i\s metals4 ,a ve9 may v>y 9 wid? f less ?an an in* up to _m y>ds1 & ! arrangem5t ( its cont5ts is also subject to mu* v>iation4 ,in/ead ( p>allel lay]s ( sp>s & ores1 frequ5tly a confus$ mass ( clay & brok5 rocks1 :i* are (t5 cem5t$ toge!r ) sp>ry matt]1 *okes up ! ve94 ,! ore 9 a ve9 may occur 9 "o or m ribs1 :i* (t5 v>y 9 ?ickness f a m]e l9e up to masses sev]al y>ds 9 wid?4 ,sometimes ! rocks are dislocat$ along ! l9e ( fissure occupi$ by a great ve92 at o!r times no dislocation c be obs]v$4 ,m9]al ve9s1 h[ev]1 d n necess>ily occupy dislocation fissures4 ,!y (t5 occur 9 cavities :i* h be5 =m$ by ! erosive action ( acidulat$ wat]1 9 ! way describ$ 9 p>s4 #ei1 #fj1 & #fa4 ,?is is frequ5tly ! case 9 calc>e\s /rata4 ,su* ve9s usually co9cide m or less ) ! b$d+ ( ! rocks1 b 9 ! case ( ?ick lime/ones !y n unfrequ5tly cut across ! b$d+ 9 a v]tical or ne>ly v]tical direction1 =m+ :at are t]m$ pipe-ve9s4 ,,dynamical ,,geology4 #eg4 ,hav+ consid]$ ! composition1 /ructure1 & arrangem5t ( ! rock-masses :i* =m ! solid cru/ ( our globe1 we h next to inquire into ! nature ( ^? physical ag5cies by ! action ( :i* ! rocks1 z we n[ see !m1 h be5 produc$4 ,! "w p]=m$ by ! v>i\s =ces employ$ 9 modify+ ! e>?'s cru/ is at "o & ! same "t de/ructive & recon/ructive4 ,rocks are be+ cont9ually demoli%$1 & out ( _! ru9s new rocks are be+ built4 ,9 o!r words1 matt] is con/antly ent]+ into new relations--n[ exi/+ z solid rock1 or 9 solution 9 wat]1 or c>ri$ z ! lighte/ du/ on ! w+s ( ! w9d2 n[ be+ swept d[n by riv]s into ! sea1 or br\ght "u ! influ5ce ( subt]ranean heat--b always *ang+1 soon] or lat]1 sl[ly or rapidly1 f "o =m to ano!r4 ,! great geological ag5ts ( *ange are ^!3 #a4 ,,! ,,atmosph]e2 #b4 ,,wat]2 #c4 ,,plants ,,& ,,animals2 #d4 ,,subt]ranean ,,=ces4 ,we %all consid] ^! 9 succession4 ,,! ,,atmosph]e4 #eh4 ,all rocks h a t5d5cy to wa/e away "u ! influ5ce ( ! atmosph]e4 ,?is is t]m$ wea!r+4 ,"u ! influ5ce ( ! sun's heat1 ! ext]nal portions ( a rock exp&1 & aga9 contract :5 !y cool at night4 ,! effect ( ?is alt]nate expansion & contraction is (t5 /rik+ly manife/ 9 tropical c\ntries3 "s rocks be+ gradually dis9tegrat$1 & crumbl+ into grit & s&2 o!rs becom+ crack$1 & ei!r exfoliat+ or break+ up all ov] _! surface into small angul> fragm5ts4 ,aga91 9 c\ntries subject to alt]nations ( extreme heat & cold1 simil> wea!r+ action takes place4 ,! *emical action ( ! atmosph]e is mo/ obs]vable 9 ! case ( calc>e\s rocks4 ,! c>bonic acid almo/ inv>iably pres5t acts z a solv5t1 s t dew & ra91 :i* o!rwise w\ld 9 _m cases h b feeble dis9tegrat+ p[]1 are enabl$ to eat into su* rocks z *alk & lime/one1 calc>e\s s&/ones1 c4 ,! oxyg5 ( ! atmosph]e also unites ) c]ta9 m9]als1 su* z ! proto-salts ( iron1 & conv]ts !m into p]oxides4 ,x is ?is action :i* produces ! r$ & yell[ f]rug9\s discolorations 9 s&/one4 ,*emical *anges also take place 9 ! case ( _m igne\s rocks1 ! result be+ t a wea!r$ 'cru/' =ms :]ev] su* rocks are expos$ to ! action ( ! atmosph]e4 ,( c\rse1 ! rate at :i* a rock wea!rs dep5ds ^u its m9]alogical & *emical composition4 ,lime/ones wea!r mu* m rapidly ?an clay-rocks2 & augitic igne\s rocks1 z a rule1 dis9tegrate m readily ?an ! m highly silicat$ species4 ,! wea!r+ action ( ! atmosph]e is also greatly aid$ by fro/1 z we %all see pres5tly4 ,! result ( all ?is wea!r+ is ! =mation ( soil--soil be+ only ! f9e-gra9$ debris ( ! wea!r$ rocks4 ,! angul> debris f\nd at ! base ( all cliffs 9 temp]ate & arctic regions1 & on e hill & m\nta9 :i* is subject$ to alt]nations ( extreme heat & cold1 is also ! effect ( wea!r+4 ,b ^! & o!r effects ( fro/ w be treat$ ( "u ! head ( ,froz5 ,wat]4 ,! hillocks & ridges ( loose s& 7s& dunes7 f\nd 9 _m places along ! sea-m>g91 & ev5 9 ! int]ior ( "s cont95ts1 z 9 ,africa & ,asia1 are due to ! action ( ! w9d1 :i* drives ! loose gra9s be=e x1 & piles !m up4 ,sometimes also ! w9d c>ries 9 susp5sion ! f9e/ du/1 :i* may be transport$ = va/ di/ances be=e x falls to ! gr\nd4 ,?us1 f9e du/ %ot into ! air by ! volcanoes ( ,icel& has be5 bl[n z f> z ! ,%etl& ,isl&s2 & 9 tropical c\ntries ! du/ ( ! dri$-up & p>*$ b$s ( lakes & riv]s is (t5 swept away dur+ hurricanes1 & c>ri$ 9 ?ick cl\ds = leagues4 ,ra9 fall+ ?r\gh ?is du/ soaks x up1 & comes d[n highly discol\r$1 br[n & r$4 ,?is is ! s-call$ blood-ra94 ,m9ute microscopic animal & vegetable organisms are (t5 comm+l$ ) ?is du/1 & fall+ into /reams1 lakes1 or ! sea1 may ?us become ev5tually buri$ 9 s$im5ts v f> remov$ f ! place t gave !m bir?4 ,,wat]4 #ei4 ,! geological action ( wat] 9 modify+ ! cru/ ( ! e>? is tw(old--namely1 *emical & me*anical4 ,und]gr\nd ,wat]4--,all ! moi/ure :i* we see fall+ z ra9 or sn[ does n fl[ imm$iately away by brooks & riv]s to ! sea4 ,"s portion ( x soaks into ! gr\nd1 & f9ds a passage = itself by cracks & fissures 9 ! rocks bel[1 f :i* x em]ges at la/ z spr+s1 ei!r at ! surface ( ! e>?1 or at ! bottom ( ! sea4 ,su* are ! m obvi\s c\rses pursu$ by ! wat]--x fl[s (f ei!r by sub-a]ial or subt]ranean *annels4 ,b a n inconsid]able portion soaks into ! solid rocks !mselves1 :i* are all m or less por\s & p]vi\s4 ,wat] ?us sl[ly soak+ (t5 effects v consid]able *emical *anges4 ,sometimes ! b9d+ matt] :i* held ! sep>ate p>ticles ( ! rock toge!r is dissolv$ out1 & ! rock is ?us r5d]$ s(t & crumbl+2 at o!r times1 ! rev]se takes place1 & ! wat] deposits1 9 ! m9ute int]/itial pores1 "s b9d+ matt] by :i* ! p>tially or :olly incoh]5t gra9s are agglut9at$ into a solid mass4 ,?us :at 7 orig9ally h>d & t\gh rocks become dis9tegrat$ to su* a degree1 t !y crumble to p[d] soon aft] !y are expos$ to ! air2 :ile "s aga9 are conv]t$ into a clay1 & may be dug readily ) a spade4 ,&1 on ! o!r h&1 loose s& is glu$ into a h>d build+-/one4 ,!re are _m o!r *anges effect$ ^u rocks by wat]1 9 virtue ( ! *emical ag5ts :i* x holds 9 solution4 ,inde$1 x may be said t !re are v few1 if any1 rocks 9 :i* ! *emical action ( int]/itial wat] has n =m]ly be51 or is n at pres5t be+1 c>ri$ on4 ,besides t :i* soaks ?r\gh ! rocks !mselves1 !re is always a l>ge proportion ( und]gr\nd wat]1 :i*1 z we h said above1 f9ds a circuit\s r\te = itself by jo9ts1 cracks1 & crevices4 ,aft] c\rs+ =1 x may be1 miles und]gr\nd1 su* wat] ev5tually em]ges z spr+s1 :i* conta9 9 solution ! v>i\s +r$i5ts :i* ! wat] has *emically extract$ f ! rocks4 ,^! +r$i5ts are !n deposit$ 9 proportion z ! m9]al wat] suff]s f evaporation4 ,wat] impregnat$ ) c>bonate ( lime1 = example1 deposits t comp\nd z soon z evaporation has c>ri$ (f a c]ta9 p]c5tage ( ! wat] itself1 & ! c>bonic acid gas :i* x held4 ,?is is ! orig9 ( ! m9]al call$ trav]t9e or calc>e\s tufa1 :i* is s commonly met ) on ! m>g9s ( spr+s1 riv]s1 & wat]falls4 #fj4 ,/alactites & /alagmites h be5 =m$ 9 a simil> way4 ,wat] sl[ly ooz+ f ! ro( ( a lime/one cav]n p>tially evaporates !re1 & a ?9 pellicle ( c>bonate ( lime is =m$2 :ile t portion ( ! wat] :i* falls to ! gr\nd1 & is !re evaporat$1 likewise gives rise to ! =mation ( c>bonate ( lime4 ,by su* con/ant dropp+ & evaporat+1 long tongue-& icicle-l p5dants 7/alactites7 gr[ d[nw>ds f ! ro(2 :ile at ! same "t domes & bosses 7/alagmites7 gr[ upw>ds f ! floor1 s z sometimes to meet ! =m] & give rise to cont9u\s pill>s & columns4 ,! great solv5t p[] ( c>bonat$ wat] is %ewn fir/ by ! *emical analysis ( spr+s1 &1 secondly1 by ! great wa/+ effects :i* ! long-cont9u$ action ( ^! has br\ght ab\t4 ,?us1 x has be5 e/imat$ t ! fifty spr+s ne> ,c>lsbad1 :i* yield eight hundr$ ?\s& cubic feet ( wat] 9 tw5ty-f\r h\rs1 conta9 9 solution z mu* lime z w\ld g to =m a mass ( /one weigh+ two hundr$ ?\s& p\nds4 ,w>m1 or1 z !y are t]m$1 !rmal spr+s1 frequ5tly c>ry away ) !m1 out ( ! b[els ( ! e>?1 va/ quantities ( m9]al matt] 9 solution4 ,! wat]s at ,ba?1 = in/ance1 are e/imat$ to br+ to ! surface an annual am\nt ( v>i\s salts1 ! mass ( :i* is n less ?an #eed cubic y>ds4 ,"o ( ! spr+s ( ,l\e*e1 ,france1 h[ev]1 c>ries out ) x no less ?an #h1hbb1djj p\nds ( gypsum annually1 :i* is equal to ab\t #babb cubic y>ds4 #fa4 ,x is easy to conceive1 !re=e1 t 9 ! c\rse ( ages great alt]ations mu/ be caus$ by spr+s4 ,caves & w9d+ gall]ies1 & irregul> *annels1 w be worn out ( ! rocks :i* are ?us be+ dissolv$4 ,especially w ?is be ! case 9 c\ntries :]e calc>e\s rocks ab\nd4 ,x is 9 su* regions1 accord+ly1 :]e we meet ) ! mo/ /rik+ examples ( caves & und]gr\nd riv]-*annels4 ,! l>ge/ cave at pres5t kn[n is ! ,mammo? ,cave1 9 ,k5tucky4 ,?is rem>kable holl[ consi/s ( num]\s w9d+ gall]ies & passages t cross & recross1 & ! unit$ l5g? ( :i* is said to be #bag miles4 ,9 calc>e\s c\ntries1 riv]s1 aft] fl[+ =1 x may be1 miles at ! surface1 sudd5ly disappe> into ! gr\nd1 & fl[ (t5 = long di/ances be=e !y reappe> 9 ! light ( day4 ,9 "s regions1 inde$1 ne>ly all ! dra9age is subt]ranean4 ,! surface ( ! gr\nd1 9 calc>e\s c\ntries1 frequ5tly %ews circul> depressions1 caus$ by ! fall+ 9 ( ! ro(s ( cav]ns4 ,sometimes1 also1 great masses ( rock1 (t5 miles 9 ext5t1 get loos5$ by ! dissolv+ action ( subt]ranean wat]1 & cra% d[nw>ds into ! valleys4 ,su* l&slips1 z !y are call$1 are n1 h[ev]1 conf9$ to calc>e\s regions4 ,9 #ahjf1 a l>ge section ( ! ,rossb]g1 a m\nta9 ly+ to ! nor? ( ! ,righi1 consi/+ ( conglom]ate ov]ly+ b$s ( clay1 ru%$ d[n into ! pla9s ( ,goldau1 ov]:elm+ f\r villages & ne>ly a ?\s& inhabitants4 ,! cause ( ?is cata/rophe 0 und\bt$ly ! s(t5+ into mud ( ! clay-b$s on :i* ! conglom]ate re/$1 = ! season :i* _h j t]m9at$ :5 ! slip took place _h be5 v wet4 ,! mass ( mat]ial t slid d[n 0 e/imat$ to conta9 upw>ds ( fifty-f\r millions ( cubic y>ds2 x rea*$ n less ?an two & a half miles 9 l5g?1 by "s ?ree hundr$ & fifty y>ds wide1 & ?irty-five y>ds ?ick4 #fb4 ,surface-wat]--,ra94--,hav+ n[ le>n$ some?+ z to ! modifications produc$ by und]gr\nd wat]1 we turn next to consid] ! action ( surface-wat]1 & ! results aris+ f t action4 ,ra91 :5 x falls to ! gr\nd1 c>ries ) x "s c>bonic acid gas :i* x has absorb$ f ! atmosph]e4 ,arm$ ) ?is solv5t1 x attacks c]ta9 rocks1 m especially lime/ones & *alk1 a c]ta9 proportion ( :i* x licks up & deliv]s ov] to brooks & /reams4 ,"u its influ5ce1 also1 ! f9] p>ticles ( ! soil are ev] sl[ly mak+ _! way f high] to l[] levels4 ,rocks :i* are be+ gradually dis9tegrat$ by wea!r+ h _! f9] gra9s & p>ticles1 ?us loos5$1 c>ri$ away by ra94 ,nor is ?is ra9-action s inconsid]able z might be suppos$4 ,9 ! g5tl] holl[s ( an undulat+ c\ntry1 we frequ5tly f9d accumulations ( clay1 loam1 & brick-e>?1 :i* (t5 rea* _m feet 9 ?ickness1 & :i* are und\bt$ly ! results ( ra9 wa%+ d[n ! p>ticles ( soil1 c4 f ! adjac5t slopes4 #fc4 ,riv]-action4--,! wat] ( /reams & riv]s almo/ inv>iably conta9s 9 solution "o or m *emical comp\nds1 & 9 ?is respect does n diff] f ! wat] ( spr+s4 ,( c\rse1 ?is m9]al matt] is d]iv$ 9 consid]able measure f spr+s1 b is also no d\bt to a l>ge ext5t tak5 up by ! riv]s !mselves1 z !y wa% ! rocks & soils on _! j\rney to ! sea4 ,! am\nt ( m9]al matt] ?us transport$ mu/ be some?+ enorm\s1 z is %ewn by ! *emical analyses ( riv]-wat]4 ,bis*( calculat$ t ! ,rh9e c>ries 9 solution z mu* c>bonate ( lime z w\ld suffice = ! ye>ly =mation ( ?ree hundr$ & ?irty-two ?\s& millions ( oy/]-%ells ( ! usual size--a quantity equal to a cube five hundr$ & sixty feet 9 ! side1 or a squ>e b$ a foot ?ick1 & upw>ds ( two miles 9 ! side4 ,b ! me*anical erosion effect$ by runn+ wat] is :at impresses u mo/ ) ! importance ( riv]s z geological ag5cies4 ,?is erosive action is due to ! gravel1 s&1 & mud c>ri$ along by ! wat]4 ,^! +r$i5ts act z files 9 ! h& ( a workman1 & gr9d1 poli%1 & r$uce ! rocks aga9/ :i* !y are borne4 ,! b$s ( "s /reams t fl[ ov] solid rock are (t5 pitt$ ) circul> holes1 at ! bottom ( :i* "o inv>iably f9ds a few r\nd$ /ones4 ,^! /ones1 kept 9 con/ant motion by ! wat]1 are ! means by :i* ! pot-holes1 z !y are call$1 h be5 excavat$4 ,:5 pot-holes are num]\s1 !y (t5 unite s z to =m curi\s smoo?-sid$ tr5*es & gullies4 ,! same fil+ action goes on all ov] ! b$ ( ! /ream :]ev] ! solid rock is expos$4 ,& :ile ! latt] is be+ gradually r$uc$1 ! /ones & grit :i* act z ! files are !mselves worn & r$uc$2 s t /ones dim9i% 9 size1 & grit passes into f9e s& & mud1 z !y move f high] to l[] levels4 ,no d\bt ! erosive action ( runn+ wat] appe>s to h b small effect 9 a %ort "t1 & we are apt1 !re=e1 to und]e/imate its p[]4 ,b :5 our obs]vations ext5d1 we see x is q o!rwise1 & t1 s f> f be+ unimportant1 runn+ wat] is really "o ( ! mo/ p[]ful ( all ! geological ag5cies t are employ$ 9 modify+ ! e>?'s cru/4 ,ev5 )9 a comp>atively %ort "t1 x is able to effect v consid]able *anges4 ,?us1 ! riv] ,simeto1 9 ,sicily1 hav+ become damm$ by a /ream ( lava fl[+ f ,etna1 succe$$1 9 two hundr$ & fifty ye>s1 9 cutt+ ?r\gh h>d solid basalt a new *annel = itself1 :i* measur$ f tw5ty to fifty metres 9 dep?1 & f twelve to eighte5 9 bread?4 ,:51 also1 we rememb] ! fact1 t no riv] is absolutely free f m9]al matt] held 9 susp5sion1 b t1 on ! contr>y1 all runn+ wat] is m or less discol\r$ ) s$im5t1 :i* is m]ely ! mat]ial d]iv$ f ! dis9tegration ( rocks1 x w appe> to u difficult to ov]e/imate ! p[] ( wat]y erosion4 ,to ! m9]al matt] held 9 susp5sion1 we h to add ! co>s] detritus1 gravel & s&1 :i* is be+ gradually pu%$ along ! b$s ( riv]s1 & :i*1 9 ! case ( ! ,mississippi1 has be5 e/imat$ to equal a mass ( sev5 hundr$ & fifty million cubic feet1 dis*>g$ annually into ! ,gulf ( ,mexico4 ,by c>eful measurem5ts1 x has also be5 asc]ta9$ t ! same riv] c>ries d[n annually into ! sea a weight ( mud held 9 susp5sion :i* rea*es ! va/ sum ( #hab1ejj1jjj1jjj p\nds4 ,! total annual am\nt ( m9]al matt]1 :e!r held 9 susp5sion or pu%$ along ! bottom ( ?is great riv]1 has be5 e/imat$ to equal a mass #bfh feet 9 height1 ) an area ( "o squ>e mile4 #fd4 ,alluvium4--,! s$im5t c>ri$ along & deposit$ by a riv] is call$ alluvium4 ,sometimes ?is alluvium cov]s wide areas1 =m+ broad flats on "o or bo? sides ( a riv]1 & 9 su* cases x is due to ! action ( ! floodwat]s ( ! /ream4 ,e "t ! riv] ov]fl[s ! l[ gr\nds ?r\gh :i* x passes1 a lay] ( s$im5t is laid d[n1 :i* has ! effect ( gradually rais+ ! level ( ! alluvial tract4 ,by & by a "t comes :5 ! riv]1 :i* has all ! :ile be5 sl[ly deep5+ its *annel1 is unable to flood ! flats1 & !reupon x beg9s to cut into ^!1 & to =m new flats at a some:at l[] level4 ,9 ?is way we (t5 obs]ve a s]ies ( alluvial t]races1 consi/+ ( gravel1 s&1 & silt1 ris+ "o above ano!r along a riv] valley4 ,su* are ! t]races ( ! ,?ames & o!r riv]s 9 ,engl&1 & ( ! ,twe$1 ,clyde1 ,tay1 c4 9 ,scotl&4 ,! great pla9s ?r\gh :i* ! ,rh9e fl[s betwe5 ,basel & ,b+51 are also well-m>k$ examples ( alluvial accumulations4 ,!re are v few /reams1 inde$1 :i* h n =m$ su* deposits along "s portion ( _! c\rse4 #fe4 ,:5 a riv] ent]s a lake1 ! motion ( ! wat] is ( c\rse *eck$1 & h5ce ! heavi] detritus1 su* z gravel & co>se s&1 moves m sl[ly =w>d1 & at la/ comes to re/ on ! b$ ( ! lake1 at no great di/ance f ! m\? ( ! riv]4 ,f9] s& & mud are c>ri$ out = "s di/ance fur!r1 b ev5tually !y also cease to move1 & s9k to ! bottom4 ,:5 ! lake is suffici5tly l>ge1 x cat*es all or ne>ly all ! matt] br\ght d[n by ! riv]1 :i*1 z x issues f ! l[] end ( ! lake1 is bright & cle>4 ,a well-kn[n example ( ?is ph5om5on is t ( ! ,rhone1 :i* ent]s ! ,lake ( ,g5eva turbid & muddy1 b ru%es out q cle> at ! l[] end ( ! lake4 ,lakes1 !re=e1 are all be+ sl[ly or m rapidly silt$ up1 & ?is1 ( c\rse1 is mo/ conspicu\s at ! po9ts :]e !y are ent]$ by riv]s4 ,?us1 at ! head ( ! ,lake ( ,g5eva1 x is manife/ t ! wide flat ?r\gh :i* ! riv] fl[s be=e x p\rs into ! lake1 has be5 conqu]$ by ! ,rhone f ! latt]4 ,9 ! times ( ! ,romans1 ! lake1 z we "k1 ext5d$ = m ?an "o mile & a half fur!r up ! valley4 #ff4 ,deltas4--,:5 !re are no lakes to int]cept fluviatile s$im5t1 ?is latt] is borne d[n to ! sea1 :]e x is deposit$ 9 precisely ! same way z 9 a lake3 ! heavi] detritus comes to re/ fir/1 ! f9] s$im5t be+ swept out = "s di/ance fur!r4 ,s t1 9 pass+ f ! riv]-m\? outw>ds1 we h at fir/ gravel1 :i* gradually gets f9] & f9] until x is replac$ by s&1 :ile ?is 9 turn is succe$$ by mud & silt4 ,!re is ?is diff]5ce1 h[ev]1 betwe5 lacu/r9e & fluvio-m>9e deposits1 t :ile ! =m] accumulate 9 wat] :i* is comp>atively /ill1 ! latt] are (t5 br\ght "u ! influ5ce ( waves & curr5ts1 & become %ift$ & sift$ to su* a degree t f9e & co>se detritus are frequ5tly comm+l$2 & !re is1 !re=e1 n ! same ord]ly succession ( co>se & f9e mat]ials :i* *>act]ises lacu/r9e deposits4 ,(t51 inde$1 ! curr5ts opposite ! m\? ( a riv] are s /rong1 t little or no s$im5t is p]mitt$ to ga!r !re4 ,usually1 h[ev]1 we f9d t riv]s h succe$$ 9 reclaim+ m or less wide tracts f ! dom9ion ( ! waves1 or at all ev5ts h cumb]$ ! b$ ( ! sea ) banks & b>s ( detritus4 ,! broad pla9s =m$ at ! m\? ( a riv] are call$ deltas1 f _! resemblance to ! ,greek lett] ,delta4 ,! deltas ( ! ,nile1 ,ganges1 & ,mississippi are among ! mo/ not$4 ,! t]m delta1 h[ev]1 is n exclusively appli$ to fluvio-m>9e deposits2 riv]s also =m deltas 9 fre%-wat] lakes4 ,x is usual1 h[ev]1 to re/rict ! t]m to ext5sive alluvial pla9s :i* are int]sect$ by _m w9d+ *annels1 due to ! rapid bifurcation ( ! riv]1 :i* beg9s to take place at ! v head ( ! great flat--t is to say1 at ! po9t :]e ! riv] orig9ally ent]$ ! sea 7or lake74 #fg4 ,froz5 ,wat]4--,we h n[ se5 :at c be done by ! me*anical action ( runn+ wat]4 ,we h next to consid] :at modifications are effect$ by freez+ & froz5 wat]4 ,wat]1 z e "o kn[s1 exp&s 9 ! act ( freez+1 & 9 do+ s ex]ts great =ce4 ,let ! read] be> 9 m9d :at has be5 said z to ! passage ( wat] ?r\gh ! m9ute & (t5 invisible pores ( rocks1 & to its pres5ce 9 cracks & crevices aft] e %[] ( ra91 & he w readily see h[ excessive mu/ be ! wa/e caus$ by ! action ( fro/4 ,! wat]1 to z great a dep? z ! fro/ ext5ds1 passes into ! solid /ate1 & 9 do+ s pu%es ! gra9s ( ! rocks asund]1 or w$ges out l>ge masses4 ,no soon] does ?aw ensue ?an ! wat]1 becom+ melt$1 all[s ! gra9s ( ! rock to fall asund]2 ! out] sk9 ( ! rock1 z x 71 is dis9tegrat$1 & crumbles away1 :ile fragm5ts & masses lose _! balance 9 _m cases1 & topple d[n4 ,h5ce x is1 t 9 all regions :]e fro/ acts1 ! hill-tops & slopes are cov]$ ) angul> fragm5ts & debris1 & a soil is readily =m$ by ! dis9tegration ( ! rocks4 ,riv]-ice is (t5 a pot5t ag5t ( geological *ange4 ,/ones get froz5 9 along ! m>g9s ( a riv]1 & (t5 debris falls d[n f cliff & scaur ^u ! surface ( ! ice2 :5 ?aw sets 91 & ! ice breaks up1 /ones & rubbi% are frequ5tly float$ = long di/ances1 & may ev5 be c>ri$ out to sea be=e _! support fails !m1 & !y s9k to ! bottom4 ,9 "s cases1 :5 ! ice is v ?ick1 x may run agr\nd 9 a riv]1 & confuse & tumble up ! deposits ga!r+ at ! bottom4 ,ice sometimes =ms ^u /ones at ! bottom ( a riv]1 & floats ^! (f2 & ?is curi\s action may take place ev5 al?\gh no ice be =m+ at ! "t on ! surface ( ! wat]4 #fh4 ,glaci]s1 ,iceb]gs1 & ,ice-foot4--,9 c]ta9 m\nta9\s di/ricts1 & 9 arctic & ant>ctic regions1 sn[ accumulates to su* an ext5t t its own weight suffices to press ! l[] portions into ice4 ,alt]nate ?aw+ & freez+ also aid 9 ! =mation ( ! ice1 :i* soon beg9s to creep d[n ! m\nta9-slopes into ! valleys1 :]e x con/itutes :at are call$ glaci]s or ice-riv]s4 ,^! great masses ( ice atta9 (t5 a great ?ickness1 & frequ5tly ext5d = _m miles along ! c\rse ( a valley4 ,9 ! ,alps !y occasionally rea* z mu* z five hundr$ or six hundr$ feet 9 dep?4 ,9 ,gre5l&1 h[ev]1 !re are glaci]s probably n less ?an five ?\s& feet ?ick2 & ! glaci] ice ( ! ant>ctic cont95t has be5 e/imat$ ev5 to rea* twelve miles 9 ?ickness4 ,glaci]s fl[ sl[ly d[n _! valleys1 at a rate :i* v>ies ) ! slope ( _! b$s & ! mass ( ! ice4 ,"s move only a few in*es1 o!rs two or ?ree feet1 9 a day4 ,_! =w>d motion is arre/$ at a po9t :]e ! ice is melt$ j z fa/ z x comes on4 ,a glaci] is always m or less seam$ ) yawn+ cracks1 :i* are call$ crevasses4 ,^! owe _! orig9 to ! unequal rate at :i* ! diff]5t p>ts ( ! ice fl[2 ?is diff]5tial motion caus+ /ra9s1 to :i* ! ice yields by snapp+ asund]4 ,! flanks ( a glaci] are usually fr+$ ) heaps ( angul> blocks & debris :i* fall f ! adjac5t rocky slopes1 & "s ( ?is rubbi% tumbl+ into ! gap+ crevasses mu/ occasionally rea* to ! bottom ( ! ice4 ,! rubbi% heaps 7sup]ficial mora9es7 travel sl[ly d[n ! valley on ! surface ( ! ice1 & are ev5tually toppl$ ov] ! end ( ! glaci]1 :]e !y =m great banks & m\nds4 ,^! are call$ t]m9al mora9es4 ,! rocky b$ ( a glaci] is inv>iably smoo!d & poli%$1 & /reak$ ) co>se & f9e /riae1 or scrat*es1 :i* run p>allel to ! direction ( ! ice-fl[4 ,^! are due to ! pres5ce1 at ! bottom ( ! ice1 ( su* angul> fragm5ts z become deta*$ f ! und]ly+ rocks1 or ( b\ld]s & rubbi% :i* h be5 introduc$ f above4 ,! /ones are gr\nd by ! ice along ! surface ( its b$1 caus+ ruts & scrat*es1 :ile ! f9] mat]ial result+ f ! gr9d+ action =ms a k9d ( poli%]4 ,! /ones act+ z grav]s are !mselves cov]$ ) /riae1 & _! %>p edges get smoo!d away4 ,9 alp9e di/ricts !re is always a good deal ( wat] circulat+ und]nea? a glaci]1 & ?is wa%es out ! s& & f9e clay4 ,?us x is t riv]s issu+ f glaci]s are always m or less discol\r$ br[n1 yell[1 gre51 gray1 or blue1 accord+ to ! nature ( ! rocks :i* ! ice has p\nd$ d[n into mud4 ,9 ,gre5l& _m ( ! l>ge glaci]s g "r out to sea1 & ow+ to _! great ?ickness are able to dispossess ! sea sometimes = miles4 ,b erelong ! great] specific gravity ( ! sea-wat] =ces (f l>ge segm5ts f ! t]m9al front ( ! ice1 :i* float away z iceb]gs4 ,l>ge masses are also always fall+ d[n f ! ice-front4 ,occasionally1 big blocks & debris are float$ away on ! iceb]gs1 b ?is does n appe> to be common4 ,9 ,gre5l& !re is v little rock-surface expos$1 f :i* blocks c be %[]$ d[n ^u ! glaci]s1 & ! surface ( ! latt] is !re=e g5]ally free f sup]ficial mora9es4 ,a k9d ( subm>9e t]m9al mora9e1 h[ev]1 ga!rs 9 front ( "s glaci]s1 made up *iefly ( ! /ones & rubbi% t are dragg$ along und]nea? ! ice1 & expos$ by ! break+-(f ( iceb]gs1 b p>tly compos$ also ( ! s& & mud wa%$ out by sub-glacial wat]s4 ,a n>r[ belt ( ice =ms along ! sea-coa/ 9 arctic regions1 :i* (t5 atta9s a ?ickness ( ?irty or =ty feet4 ,?is is call$ ! ice-foot4 ,x becomes load$ ) debris & blocks1 :i* fall ^u x f ! cliffs above2 &1 z l>ge portions are frequ5tly deta*$ f ! cliffs 9 summ]-"t1 !y sail (f ) _! c>goes ( debris1 & drop ^! ov] ! sea-bottom z !y gradually melt away4 ,! ice-foot is ! great di/ributor ( erratics or w&]$ blocks1 ! "p tak5 9 ?is action by ! huge iceb]gs :i* are dis*>g$ by ! glaci]s be+1 comp>atively speak+1 insignificant4 ,b :5 ^! latt] run agr\nd1 !y mu/ (t5 cause great confusion among ! b$s ( f9e mat]ial accumulat+ ^u ! floor ( ! sea4 #fi4 ,! ,sea4--,sea-wat] owes its saltness to ! pres5ce ( v>i\s m or less soluble sub/ances1 su* z common salt1 gypsum1 ,epsom salts1 *loride ( magnesium1 c4 ,besides ^!1 !re are o!r +r$i5ts held 9 solution1 :i*1 al?\gh !y c be detect$ 9 only m9ute quantities 9 sea-wat]1 are yet ( ! v utmo/ importance to m>9e creatures4 ,?is is ! case ) c>bonate ( lime1 va/ quantities ( :i* are c>ri$ d[n by _m riv]s to ! sea4 ,b x mu/ be ne>ly all us$ up 9 ! =mation ( h>d %ells & skeletons by molluscs1 cru/aceans1 corals1 c41 = v little c be trac$ 9 ! wat] itself4 ,silica is also met ) sp>+ly1 & is ab/ract$ by "s creatures to =m _! h>d cov]+s4 #gj4 ,break]-action--,curr5ts4--,! mo/ conspicu\s action ( ! sea1 z a geological ag5t1 takes place along its m>g91 :]e ! break]s are hurl$ aga9/ ! l&4 ,/ones & gravel are borne ) m or less int5se =ce aga9/ ! rocks1 & by _! con/ant batt]+ succe$ ev5tually 9 und]m9+ ! cliffs1 :i* by & by become top-heavy1 & l>ge masses fall d[n & get brok5 up & p\nd$ into gravel & s&4 ,! new wall ( rock ?us expos$ becomes 9 turn assault$1 & 9 c\rse ( "t is und]m9$ 9 l mann]4 ,! wa/e ( ! cliffs is greatly aid$ by ! action ( fro/1 :i* loos5s ! jo9t$ rocks1 & r5d]s !m an easi] prey to ! =ce ( ! waves4 ,( c\rse1 ! rapidity ) :i* a coa/-l9e is eat5 into dep5ds v mu* ^u ! nature ( ! rocks4 ,:]e ^! are =m$ ( loose mat]ials l s&1 gravel1 or clay1 consid]able inroads are effect$ by ! sea 9 a comp>atively %ort "t4 ,?us1 along "s p>ts ( ! ,engli% coa/1 z betwe5 ,flambor\gh ,head & ! m\? ( ! ,humb]1 & betwe5 ! ,wa% & ! ,?ames1 x is e/imat$ t ! l& is wa/$ away at ! rate ( a y>d p] annum4 ,:]e h>d rocks =m ! coa/-l9e ! rate ( wa/e is (t5 exce$+ly sl[1 & c5turies may elapse )\t any app>5t *ange be+ effect$4 ,:5 ! rocks are ( unequal h>dness ! coa/-l9e becomes v irregul>1 ! sea c>v+ out bays & gullies 9 ! s(t] portions1 :ile ! m durable masses /& out z capes & bold headl&s4 ,n unfrequ5tly1 su* headl&s are conv]t$ into sea-/acks & rocky islets1 z "o may obs]ve along ! rocki] p>ts ( our %ore-l9es4 ,close in%ore1 ! bulki] debris d]iv$ f ! wa/e ( ! l& (t5 accumulates1 =m+ b$s & banks ( %+le & gravel4 ,! f9] mat]ials are c>ri$ f>!r out to sea1 & di/ribut$ ov] ! sea-floor by ! action ( ! tide & curr5ts4 ,tidal & o!r curr5ts may also h "s d5ud+ effect ^u ! sea-bottom1 b ?is c only be 9 comp>atively %all[ wat]4 ,! great bulk ( ! mat]ial d]iv$ f ! wa/e ( ! coa/s by ! me*anical action ( ! break]s1 travels = no great di/ance4 ,b ! f9e mud br\ght d[n by riv]s is frequ5tly transport$ = va/ di/ances be=e x settles4 ,s f9e1 inde$1 is "s ( ?is s$im5t>y mat]ial1 t x may be c>ri$ 9 susp5sion by sea-curr5ts = ?\s&s ( miles be=e x s9ks to ! bottom4 #ga4 ,f ?is %ort outl9e x becomes evid5t1 !re=e1 t ! co>s]-gra9$ ! deposit1 ! small] w be ! area x cov]s2 :ile conv]sely1 ! f9] ! accumulation1 ! m widely w x be di/ribut$4 ,a p>tial exception to ?is rule is t ( ! debris scatt]$ ov] ! bottom ( ! ocean by iceb]gs & deta*$ portions ( ice-foot4 ,^! are (t5 float$ = va/ di/ances by curr5ts be=e !y f9ally melt away1 & h5ce ! co>se debris transport$ by !m mu/ be v widely di/ribut$ ov] t "p ( ! sea-bottom :i* is trav]s$ by curr5ts fl[+ out ( ! ,arctic & ,ant>ctic ,oceans4 ,al?\gh ! deep] recesses ( ! ocean appe> to be cov]$ only ) ooze & f9e mud1 yet 9 "s in/ances co>se s&1 & ev5 small /ones1 h be5 br\ght up f dep?s ( a hundr$ fa?oms1 s t curr5ts may occasionally c>ry co>s] mat]ials = great di/ances f ! %ore4 ,! %ift+ action ( tidal curr5ts succe$s 9 giv+ rise to v irregul> deposits 9 %all[ seas4 ,! s\nd+s (t5 %ew sudd5 *anges f gravel to s& & mud1 nor c !re be any d\bt t1 c\ld we lay b>e ! sea-bottom1 we %\ld (t5 obs]ve gravel %ad+ (f into s&1 & s& into mud1 & vice v]sa4 ,b z we rec$$ f ! %ore1 & approa*$ areas :i* 7 once deeply subm]g$1 we %\ld f9d t ! *ange ( mat]ial 0 g5]ally f co>se to f9e4 ,,geological ,,action ,,( ,,plants ,,& ,,animals4 #gb4 ,plants4--,! dis9tegration ( rocks is (t5 aid$ by ! action ( plants1 :i* =ce _! roots into jo9ts & crevices1 & ?us loos5 blocks & fragm5ts4 ,c>bonic acid1 d]iv$ f ! decay ( plants1 be+ absorb$ by ra9-wat]1 acts *emically ^u _m rocks1 z 9 ! case ( lime/one 7see #ei1 #fj1 #fa74 ,9 temp]ate regions1 vegetation frequ5tly accumulates1 "u c]ta9 conditions1 to =m v consid]able masses4 ,( su* a nature is peat1 :i*1 z is well kn[n1 cov]s _m ?\s&s ( acres 9 ! ,briti% ,isl&s4 ,?is sub/ance is compos$ fundam5tally ( ! bog-moss 7,sphagnum palu/re71 ) :i*1 h[ev]1 are usually associat$ _m o!r m>%-lov+ plants4 ,! l[] p>ts ( bog-moss die & decay :ile its upp] portions cont9ue to fl\ri%1 & ?us1 9 process ( "t1 a ?ickness ( peat is accumulat$ to ! ext5t ( six1 twelve1 tw5ty-f\r1 or ev5 =ty feet4 ,_m ( ! hill-tops & hill-slopes 9 ,scotl& & ,irel& are cov]$ ) a few feet ( peat1 b x is only 9 valleys & holl[s :]e ! peat-bogs atta9 _! greate/ dep?4 ,9 n a few cases1 ! bogs seem to occupy ! sites ( anci5t lakes1 %ell-m>l (t5 occurr+ at ! bottom ( ^!4 ,! trunks & roots ( trees are also commonly met ) und]nea? peat1 & occasionally ! rema9s ( l& animals4 ,frequ5tly1 inde$1 x w\ld seem z if ! ov]?r[ ( ! trees1 by ob/ruct+ ! dra9age ( ! c\ntry1 _h giv5 rise to a m>%1 & ! consequ5t =mation ( peat4 ,"s ( ! mo/ valuable peat closely resembles lignite1 & makes a good fuel4 ,9 tropical c\ntries1 ! rapidity ) :i* vegetation decays prev5ts1 z a rule1 any great accumulation tak+ place2 b ! mangrove swamps are exceptions4 #gc4 ,animals4--,! action ( animal life is = ! mo/ "p cons]vative & recon/ructive4 ,consid]able accumulations ( %ell-m>l take place 9 fre%-wat] lakes1 & ! flat bottoms :i* m>k ! sites ( lakes :i* h be5 dra9$ are frequ5tly dug to obta9 ?is mat]ial4 ,b by f> ! mo/ conspicu\s =mations due to ! action ( animal life accumulate 9 ! sea4 ,molluscs1 cru/aceans1 corals1 & ! l1 secrete f ! ocean ! c>bonate ( lime ( :i* _! h>d %ells & skeletons are compos$1 & ^! h>d p>ts g to ! =mation ( lime/one4 ,! mo/ rem>kable masses ( mod]n lime/one occur )9 int]tropical regions4 ,^! are ! coral reefs ( ! ,pacific & ,indian ,oceans4 ,illu/ration3 ,fig4 #bd4--;,=mation ( ,coral ,reefs4 #gd4 ,coral is ! calc>e\s skeleton ( c]ta9 small s(t-bodi$ gelat9\s animals call$ act9ozoa4 ,^! zoophytes fl\ri% only 9 cle> wat]1 ! temp]ature ( :i* is n bel[ #ff deg4 ,f41 & !y _c live at great] dep?s ?an "o hundr$ feet4 ,!re are ?ree k9ds ( coral reef--namely1 fr++ reefs1 b>ri] reefs1 & atolls4 ,fr++ reefs occur1 z a rule1 ne> to ! %ore2 b if ?is latt] be g5tly slop+1 !y may ext5d = "o or ev5 two miles out to sea2 z f>1 inde$1 z ! dep? ( wat] is n too great = ! act9ozoa4 ,b>ri] reefs are met ) at great] di/ances f ! l&1 & (t5 rise f pr(\nd dep?s4 ,! b>ri] reef :i* ext5ds along ! nor?-ea/ coa/ ( ,au/ralia1 (t5 at a di/ance f ! l& ( fifty or sixty miles1 /ret*es1 ) int]ruptions1 = ab\t #abej miles1 ) a bread? v>y+ f t5 to n9ety miles4 ,9 "s places1 ! dep? ( ! sea imm$iately outside ( ?is reef exce$s #ahjj feet4 ,sometimes b>ri] reefs completely encircle an isl& or isl&s1 :i* are usually m\nta9\s1 z 9 ! case ( ,p\ynipete1 an isl& 9 ! ,c>ol9e ,ar*ipelago1 & ! ,gambi] ,isl&s 9 ! ,l[ ,ar*ipelago4 ,atolls are m or less irregul> r+-%ap$ reefs inclos+ a lagoon ( quiet wat]4 ,!y usually rise f pr(\nd dep?s2 ,keel+ ,atoll1 9 ! ,indian ,ocean1 is a good example4 ,! upp] surface ( atolls & b>ri] reefs (t5 pe]s at sep>ate po9ts above ! level ( ! sea1 s z to =m l[-ly+ islets4 ,9 "s cases1 ! l& ?us =m$ is almo/ co-ext5sive ) ! reef1 & be+ clo!d ) palms & tropical v]dure1 resembles a beautiful *aplet float+1 z x 71 9 mid-ocean4 ,! rock ( a coral reef is a solid :ite lime/one1 simil> 9 composition to t ( ! lime/ones occurr+ 9 ?is c\ntry4 ,9 "s places1 x is q compact1 %ew+ few or no inclos$ %ells or o!r animal rema9s2 9 o!r places1 x is made up ( brok5 & comm9ut$ corals cem5t$ toge!r1 or ( masses ( coral /&+ z !y sl[ly grew1 ) ! spaces betwe5 ! sep>ate clumps fill$ up ) coral s& & triturat$ fragm5ts & grit ( coral & %ell4 ,! ?ickness ( ! reefs is (t5 v great1 rea*+ 9 _m cases to ?\s&s ( feet4 ,at ! ,fijis1 ! reef c h>dly be less ?an #bjjj or #cjjj feet ?ick4 ,bel[ a dep? ( "o hundr$ feet1 all ! coral rock is dead1 & s9ce ! coral zoophytes d n live at great] dep?s ?an ?is1 x foll[s t ! b$ ( ! sea 9 :i* coral reefs occur mu/ h sl[ly subsid$ dur+ a long c\rse ( ages4 ,mr ,d>w9 0 ! fir/ to give a reasonable explanation ( ! orig9 ( coral reefs4 ,briefly /at$1 8 explanation is z foll[s3 ,! corals began to gr[ fir/ 9 wat] n exce$+ "o hundr$ feet 9 dep?1 & built up to ! surface ( ! sea1 ?us =m+ a fr++ reef at no great di/ance f ! l&4 ,?is initial /ep is %ewn at ,a1 ,b1 9 ! accompany+ section across a coral isl&4 ,a1 ,a1 are ! out] edges ( ! fr++ reef2 ,b1 ,b1 ! %ores ( ! isl&2 & ,s#a ! level ( ! sea4 ,subsid5ce ensu+1 ! isl& & ! sea-bottom s9k sl[ly d[n1 :ile ! coral animals cont9ue to gr[ to ! surface--! build+ ( ! reef keep+ pace ) ! subsid5ce4 ,by & by ! isl& s9ks to ! level ,s#b1 :5 ,b'1 ,b'1 repres5t ! %ores ( ! n[ dim9i%$ isl&1 & ,a'1 ,a'1 ! out] edges ( ! reef1 :i* has become a b>ri] reef2 ,c1 ,c1 be+ ! lagoon betwe5 ! reef & ! c5tral isl&4 ,we h n[ only to suppose a cont9uance ( ! subm]g5ce to ! level ,s#c1 :5 ! isl& disappe>s1 its site be+ occupi$ by a lagoon1 ,c'--! reef1 :i* has at ! same "t become an atoll1 be+ %ewn at ,a''1 ,a''4 #ge4 ,9 extra-tropical latitudes1 great accumulations ( c>bonate ( lime are also tak+ place4 ,! bottom ( ! ,atlantic has be5 f\nd to be cov]$1 ov] va/ areas1 by a f9e calc>e\s /icky deposit call$ ooze1 :i* w\ld appe> to consi/ = ! mo/ "p ( ! skeletons ( m9ute animal organisms1 call$ ,=am9if]a4 ,?is accumulation1 :5 dri$1 closely resembl$ *alk1 & !re c be no d\bt t 9 ! deep recesses ( ! ,atlantic we h ?us a gradually increas+ deposit ( c>bonate ( lime1 :i* rivals1 if x does n exce$1 9 ext5t ! mo/ widely spread calc>e\s rocks ) :i* we are acqua9t$4 ,a small p]c5tage ( silice\s mat]ials occurs 9 ! ooze1 made up p>tly ( granules ( qu>tz1 & p>tly ( ! skeletons & cov]+s ( m9ute animal & vegetable organisms4 ,:5 9 process ( "t ! *emical =ces beg9 to act ^u ! silice\s matt] diffus$ ?r\gh ! ,atlantic ooze1 segregation1 or ! ga!r+ toge!r ( ! p>ticles1 may take place1 & nodules ( fl9t w be ! result1 simil> to ! fl9t nodules :i* occur 9 *alk1 & ! *]ty concretions 9 lime/ones4 ,animalcules ) silice\s envelopes & skeletons are by no means s abundant z ^? t secrete c>bonate ( lime1 b !y are v widely diffus$ ?r\gh ! oceans1 & 9 fav\rable places are s abundant t !y may well give rise ev5tually to ext5sive b$s ( fl9t4 ,ehr5b]g calculat$ t #ag1idf cubic feet ( ^! organisms 7 =m$ annually 9 ! muddy bottom ( ! h>b\r at ,wism>1 9 ! ,baltic4 ,x w\ld appe> f rec5t obs]vations 7,*all5g] exp$ition7 t ! calc>e\s ooze at ! bottom ( ! ,atlantic & ,s\!rn ,oceans1 :i* occurs at a mean dep? ( #bbej fa?oms1 passes gradually z ! ocean deep5s into a gray ooze1 :i* is less calc>e\s1 & :i* occurs at a mean dep? ( #bdjj fa?oms4 ,at /ill great] dep?s ?is gray ooze also disappe>s1 & is replac$ by r$ clay at a mean dep? ( #bgjj fa?oms4 ,! m9ute creatures 7=am9if]a & pelagic mollusca *iefly7 ^: %ells g to =m ! calc>e\s ooze1 live = ! mo/ "p on ! surface1 & sw>m all ov] ! areas 9 :i* ooze & r$ clay occur at ! bottom4 ,h5ce x seems probable t ! clay is m]ely ! insoluble residue or a%1 z x 71 ( ! organisms--! delicate %ells1 z !y sl[ly s9k to ! m pr(\nd dep?s1 be+ dissolv$ by ! free c>bonic acid1 :i*1 z obs]vations w\ld seem to %ew1 occurs r 9 excess at great dep?s4 ,?us we see h[ ! organic =ces may give rise to ext5sive accumulations ( inorganic matt]1 closely resembl+ ! f9e/ silt or mud :i* is c>ri$ d[n to ! sea by riv]s1 & di/ribut$ f> & wide by ocean curr5ts4 ,,subt]ranean ,,=ces4 #gf4 ,!re h be5 _m speculations z to ! condition ( ! int]ior ( ! e>?4 ,"s h inf]r$ t ! ext]nal cru/ ( ! globe incloses a fluid or molt5 mass2 o!rs ?9k x m probable t ! int]ior is solid1 b conta9s scatt]$ ?r\gh\t its bulk1 especially t[>ds ! surface ( ! e>?1 irregul> seas ( molt5 matt]1 occupy+ l>ge vesicles or tunnels 9 ! solid honey-comb$ mass4 ,at pres5t1 ! facts kn[n w\ld appe> to be be/ expla9$ by ! latt] hypo!sis4 ,all t we "k f obs]vation is1 t ! temp]ature increases z we desc5d f ! surface4 ,! rate ( increase is v v>iable4 ,?us1 9 ! ,artesian well at ,neuff51 9 ,wu]temb]g1 x 0 z mu* z #a deg4 ,f4 = e #ai feet4 ,9 ! m9es ( ,c5tral ,g]many1 h[ev]1 ! increase is only #a deg4 ,f4 = e #gf feet2 :ile 9 ! ,duk9field coal-pit1 ne> ,man*e/]1 ! increase 0 /ill less1 be+ only #a deg4 ,f4 9 #hi feet4 ,tak+ ! av]age ( _m obs]vations1 x may be held z pretty well prov$ t ! temp]ature ( ! e>?'s cru/ increases #a deg4 = e #ej or #fj feet ( desc5t aft] ! fir/ hundr$4 #gg4 ,! cru/ ( ! e>? is subject to c]ta9 movem5ts1 :i* are ei!r sudd5 & p>oxysmal1 or protract$ & tranquil4 ,! =m] are kn[n z e>?quakes1 :i* may or may n result 9 a p]man5t alt]ation ( ! relative level ( l& & sea2 ! latt] always effect "s p]man5t *ange1 ei!r ( upheaval or depression4 #gh4 ,e>?quakes h be5 v>i\sly acc\nt$ =4 ,^? :o uphold ! hypo!sis ( a fluid int]ior ?9k ! undulatory motion exp]i5c$ at ! surface is caus$ by movem5ts 9 ! und]ly+ molt5 mass--an e>?quake be+ ?us '! reaction ( ! liquid nucleus aga9/ ! out] cru/4' ,by o!rs1 aga91 e>?quakes are suppos$ to be caus$ by ! fall ( l>ge rock-masses f ! ro(s ( subt]ranean cavities1 or by any sudd5 impulse or bl[1 su* z might be produc$ by ! crack+ ( rocks 9 a /ate ( t5sion1 by a sudd5 volcanic outbur/1 or sudd5 g5]ation or cond5sation ( /eam4 ,9 support ( ?is latt] hypo!sis1 _m facts may be adduc$4 ,! undulatory motion communicat$ to ! gr\nd dur+ gunp[d] explosions1 or by ! fall ( rocks f a m\nta91 is (t5 propagat$ to great di/ances f ! sc5e ( ^! cata/rophes1 & ! ph5om5a closely resemble ^? :i* accompany a true e>?quake4 ,:5 ! level ( a di/rict has be5 p]man5tly affect$ by an e>?quake1 ! movem5t has g5]ally result$ 9 a l[]+ ( ! surface4 ,?us1 9 #ahai1 ! ,great ,runn ( ,cut*1 9 ,h9du/an1 0 depress$ ov] an area ( sev]al ?\s& squ>e miles1 s z dur+ ! monsoons to become a salt lagoon4 ,occasionally1 h[ev]1 we f9d t elevation ( ! l& has tak5 place dur+ an e>?quake4 ,?is 0 ! case 9 ,new ,zeal& 9 #ahee1 :5 ! gr\nd on :i* ! t[n ( ,well+ton /&s rose ab\t two feet1 & a cape 9 ! neighb\rhood ne>ly t5 feet4 ,sometimes ! gr\nd s elevat$ is1 aft] a %ort] or long] p]iod1 aga9 depress$ to its =m] level4 ,a good example ( ?is occurr$ 9 ,s\? ,am]ica 9 #ahce4 ,! %ore at ,concepcion 0 rais$ a y>d & a half2 & ! ,isle ,santa ,m>ia 0 pu%$ up two & a half y>ds at "o end1 & ?ree & a half y>ds at ! o!r4 ,b only a few mon?s aft]w>ds ! gr\nd sank aga91 & ev]y?+ return$ to its old position4 ,! heav+ & undulatory motion ( an e>?quake produces frequ5tly consid]able *anges at ! surface ( ! gr\nd1 besides an alt]ation ( level4 ,rocks are loos5$1 & sometimes hurl$ d[n f cliff & m\nta9-side1 & /reams are occasionally damm$ ) ! soil & rubbi% pit*$ into !m4 ,sometimes also ! gr\nd op5s1 & swall[s :atev] *ances to come 9 ! way4 ,if ^! *asms close aga9 p]man5tly1 no *ange 9 ! physiography ( ! l& may take place1 b sometimes !y rema9 op51 & affect ! dra9age ( ! c\ntry4 #gi4 ,movem5ts ( ,upheaval & ,depression4--,besides ! p]man5t alt]ation ( level :i* is sometimes ! result ( a great e>?quake1 x is n[ well kn[n t ! cru/ ( ! e>? is subject to long-cont9u$ & tranquil movem5ts ( elevation & depression4 ,! cause ( ^! movem5ts is at pres5t m]ely matt] = speculation1 "s be+ ( op9ion t !y may be caus$ by ! gradual contraction ( ! sl[ly cool+ nucleus ( ! e>?1 :i* w\ld necess>ily give rise to depression1 :ile ?is movem5t1 aga91 w\ld be accompani$ by "s degree ( elevation--! result ( ! lat]al pu% or ?ru/ effect$ by ! desc5d+ rock-masses4 ,x is d\btful1 h[ev]1 if ?is hypo!sis w expla9 all ! appe>ances4 ,! ,sc&9avian p59sula af=ds a f9e example ( ! movem5ts 9 "q4 ,at ! extremity ( ! p59sula 7,scania71 ! l& is sl[ly s9k+1 :ile to ! nor? ( t di/rict gradual elevation is tak+ place at a v v>iable rate1 :i* 9 "s places rea*es z mu* z two or ?ree feet 9 a c5tury4 ,movem5ts ( elevation are also affect+ ,spitzb]g51 ,nor!rn ,sib]ia1 ,nor? ,gre5l&1 ! :ole we/]n bord]s ( ,s\? ,am]ica1 ,japan1 ! ,kurile ,isl&s1 ,asia ,m9or1 & _m o!r di/ricts 9 ! ,m$it]ranean area1 besides v>i\s islets 9 ! great ,pacific ,ocean4 ,! pro(s ( a sl[ movem5t ( elevation are f\nd 9 old sea-bea*es & sea-caves1 :i* n[ /& above ! level ( ! sea4 ,9 ! case ( ,sc&9avia1 x has be5 notic$ t ! p9e-woods :i* clo! ! m\nta9s are be+ sl[ly elevat$ to ung5ial heights1 & are !re=e gradually dy+ out along _! upp] limits4 ,! pro(s ( depression ( ! l& are se5 9 subm]g$ =e/s & peat1 :i* occur frequ5tly ar\nd our own %ores1 & !re is also /rong human te/imony to su* d[nw>d movem5ts ( ! surface4 ,! case ( ,scania has already be5 ref]r$ to4 ,sev]al /reets 9 "s ( its coa/ t[ns h sunk bel[ ! sea1 & x is calculat$ t ! ,scanian coa/ has lo/ to ! ext5t ( ?irty-two y>ds 9 bread? )9 ! pa/ hundr$ & ?irty ye>s4 ,! coral reefs ( s\!rn oceans also af=d /rik+ evid5ce ( a great movem5t ( depression4 ,n long ago a !ory 0 />t$ by a ,fr5* savant1 ,m4 ,adhem>1 to acc\nt = *anges 9 ! sea-level1 )\t hav+ rec\rse to subt]ranean ag5cy4 ,he po9t$ out t a va/ ice-cap1 cov]+ ! nor!rn regions ( our hemisph]e1 z 0 c]ta9ly ! case dur+ :at is t]m$ ! glacial epo*1 w\ld cause a rise ( ! sea by displac+ ! e>?'s c5tre ( gravity4 ,mr ,james ,croll has rec5tly /rongly support$ ?is op9ion2 & !re c be no d\bt t we h "h a v]a causa ( consid]able mutations ( level4 ,x is unque/ionably true1 h[ev]1 t great oscillatory movem5ts1 su* z describ$ above1 & :i* c only be attribut$ to subt]ranean ag5cies1 h frequ5tly tak5 & are /ill tak+ place4 #hj4 ,su* movem5ts ( ! e>?'s cru/ _c take place )\t effect+ "s *ange ^u ! /rata ( :i* t cru/ is compos$4 ,dur+ depression ( ! curv$ surface ( ! e>?1 ! "u /rata mu/ necess>ily be subject$ to int5se lat]al pressure1 s9ce !y are compell$ to occupy less space1 & contortion & plication w be ! result4 ,x is evid5t also t contortion w dim9i% f bel[ upw>ds1 s t we c conceive t excessive contortion may be ev5 n[ tak+ place at a great dep? f ! surface 9 ,gre5l&4 ,dur+ a movem5t ( elevation1 on ! o!r h&1 ! /rata are subject$ to excessive t5sion1 & mu/ be seam$ ) great r5ts3 :5 ! elevat+ =ce is remov$1 ! disrupt$ rocks w settle d[n unequally--9 o!r words1 !y w be fault$1 & _! cont9uity w be brok54 ,b bo? contortion & fault+ may be due1 on a small scale1 to local causes1 su* z ! intrusion ( igne\s rocks1 ! consolidation ( /rata1 ! fall+ 9 ( old wat]-c\rses1 c4 ,cleavage is believ$ to h be5 caus$ by compression1 su* z ! rocks might well be subject$ to dur+ great movem5ts ( ! e>?'s cru/4 ,! p>ticles ( :i* ! rock is compos$ are compress$ 9 "o direction1 & ( c\rse are at ! same "t drawn out at "r angles to ! pressure4 ,?is is obs]v$ n only z reg>ds ! p>ticles ( ! rock !mselves1 b imb$d$ fossils also are di/ort$ & flatt5$ 9 precisely ! same way4 #ha4 ,volcanoes4--,besides movem5ts ( elevation & depression1 !re are c]ta9 o!r ph5om5a due to ! action ( ! subt]ranean =ces4 ,su* are ! ejection f ! int]ior ( ! e>? ( heat$ matt]s1 & _! accumulation ^u ! surface4 ,! erupt$ mat]ials consi/ ( molt5 matt] 7lava71 /ones & du/1 gases & /eam--! lava1 a%es1 & /ones gradually accumulat+ r\nd ! focus ( ejection1 & ?us t5d+ to =m a conical hill or m\nta94 ,c\ld we obta9 a complete section ( su* a volcanic cone1 we %\ld f9d x built up ( successive irregul> b$s ( lava1 & lay]s ( /ones & a%es1 dipp+ outw>ds & away f ! s\rce ( eruption1 b hav+ r\nd ! walls ( ! crat] 7t is1 ! cavity at ! summit ( ! truncat$ cone7 a m or less p]ceptible dip inw>ds4 ,fig4 #be gives a cond5s$ view ( ! g5]al ph5om5a accompany+ an eruption4 ,9 ?is ideal section1 a is ! funnel or neck ( ! volcano fill$ ) lava2 b1 b1 ! crat]4 ,! molt5 lava is highly *>g$ ) ela/ic fluids1 :i* cont9ually escape f its surface ) viol5t explosions1 & rise 9 globul> cl\ds1 d1 d1 to a c]ta9 height1 aft] :i* !y dilate into a d>k cl\d1 c4 ,f ?is cl\d %[]s ( ra91 e1 are frequ5tly dis*>g$4 ,l>ge & small portions ( ! inc&esc5t lava are %ot upw>ds z ! imprison$ vap\r ( wat] explodes & makes its escape1 &1 along ) ^!1 fragm5ts ( ! rocks =m+ ! walls ( ! crat] & ! funnel are also viol5tly dis*>g$2 ! cool$ bombs1 angul> /ones1 & lapilli1 z ! small] /ones are call$1 fall+ 9 %[]s1 f1 ^u ! ext]ior p>ts ( ! cone or into ! crat]1 f :i* !y are aga9 & aga9 eject$4 ,mo/ frequ5tly ! great weight ( ! lava inside ! crat] suffices to break d[n ! side ( ! cone1 & ! molt5 rock escapes ?r\gh ! brea*4 ,sometimes1 h[ev]1 x issues f b5ea? ! base ( ! cone4 ,at o!r times1 f9d+ = itself "s weak place 9 ! cone1 x may fl[ out by a lat]al fissure1 g4 ,9 ! diagram1 i1 i repres5ts ! lava /ream+ d[n ! outw>d slopes1 jets ( /eam & fum>oles escap+ f almo/ e "p ( its surface4 ,=k$ lightn+ (t5 accompanies an eruption1 & is suppos$ to be g5]at$ by ! int5se mutual friction 9 ! air ( ! eject$ /ones4 ,! trituration to :i* ^! are subject$ r$uces !m1 fir/1 to a k9d ( co>se gravel 7lapillo72 !n to s& 7puzzolana72 & la/ly1 to f9e du/ or a%es 7c5]i74 ,illu/ration3 ,fig4 #be4--;,diagrammatic ,section ( ,volcano4 #hb4 ,lava4--,any rock :i* has be5 erupt$ f a volcano 9 a molt5 /ate is call$ lava4 ,"s mod]n lava-/reams cov] a great ext5t ( surface4 ,"o ( two /reams :i* issu$ f ! volcano ( ,skaptur ,jokul 7,icel&7 9 #aghc ov]fl[$ an area fifty miles 9 l5g?1 ) a bread? 9 places ( fifte52 ! o!r 0 n mu* less ext5sive1 be+ =ty miles 9 l5g?1 ) an occasional bread? ( sev54 ,9 "s places ! lava exce$$ #ejj feet 9 ?ickness4 ,aga91 9 #ahee1 an eruption 9 ! isl& ( ,hawaii s5t =? a /ream ( lava sixty-five miles long1 & f "o to t5 miles wide4 ,! surface ( a /ream quickly cools & consolidates1 & 9 do+ s %r9ks1 s z to become seam$ ) cracks1 ?r\gh :i* ! inc&esc5t matt] und]nea? c be se54 ,z ! curr5t fl[s on1 ! upp] cru/ sep>ates into r\gh ragg$ scori=m blocks1 :i* are roll$ ov] ea* o!r & jamm$ into confus$ masses4 ,! slags t cake ^u ! face or front ( ! /ream roll d[n be=e x1 & ?us a k9d ( rude pavem5t is =m$1 ^u :i* ! lava advances & is ev5tually consolidat$4 ,?us1 9 mo/ cases1 a b$ ( lava is scoriace\s z well bel[ z above4 ,o!r k9ds ( lava are mu* m ductile & visc\s1 & coagulate sup]ficially 9 glossy or wr9kl$ cru/s4 ,:5 lava has inclos$ fragm5ts ( aque\s rocks1 su* z lime/one1 clay1 or s&/one1 ^! are obs]v$ to h und]gone "s alt]ation4 ,! s&/one is (t5 mu* h>d5$1 ! clay is porcela9is$1 & ! lime/one1 /ill reta9+ its c>bonic acid1 assumes a cry/all9e texture4 ,b ! aque\s rock ^u :i* lava has cool$ does n usually exhibit mu* *ange1 nor does ! alt]ation1 z a rule1 ext5d m ?an a few feet 7(t5 only a few in*es7 into ! rock4 ,a lava-curr5t :i* ent]$ a lake or ! sea1 h[ev]1 has sometimes caught up mu* ( ! s$im5t ga!r+ !re1 & become s comm+l$ ) x1 t 9 "s p>ts x is h>d to say :e!r ! result+ rock is m igne\s or aque\s4 ,lava :i* has be5 squirt$ up f bel[ into cracks & crevices1 & !re consolidat$ s z to =m dykes1 sometimes1 b n (t51 produces consid]able alt]ation ^u ! rocks :i* x int]sects4 ,! basaltic /ructure is believ$ to be due to ! contraction ( lava consequ5t ^u its cool+4 ,! axes ( ! prisms are always p]p5dicul> to ! cool+ surface or surfaces1 & 9 "s cases ! columns are wond]fully regul>4 ,!re are num]\s v>ieties ( lava1 su* z basalt1 obsidian1 pit*/one1 pe>l/one1 tra*yte1 c42 "s are heavy compact rocks1 o!rs are light & por\s4 ,_m are f9ely or co>sely cry/all9e2 o!rs h a glassy & res9\s or waxy texture4 ,"s %ew a flaky or lam9at$ /ructure2 o!rs are concretion>y4 ,mo/ ( ! lava rocks1 h[ev]1 are granul>ly cry/all9e4 ,9 _m1 a vesicul> "* is obs]v$4 ,^! vesicles1 be+ due to ! bubbles ( vap\r t ga!r$ 9 ! molt5 rock1 usually occur 9 greate/ abundance t[>ds ! upp] surface ( a b$ ( lava4 ,!y are also m or less well develop$ ne> ! bottom ( a b$1 :i*1 z already expla9$1 is frequ5tly scoriace\s4 ,occasionally ! vesicles are dissem9at$ ?r\gh\t ! entire rock4 ,z a rule1 ^? lavas :i* are ( inf]ior specific gravity are mu* m vesicul> ?an ! d5s] & heavi] v>ieties4 ,! vesicles are usually m or less flatt5$1 hav+ be5 drawn out 9 ! direction 9 :i* ! lava-curr5t fl[$4 ,sometimes !y are fill$1 or p>tially fill$1 ) m9]al matt] introduc$ at ! "t ( eruption1 or subsequ5tly br\ght 9 a /ate ( solution & deposit$ !re by wat] filt]+ ?r\gh ! rock3 ?is =ms :at is call$ amygdaloidal lava4 ,9 volcanic di/ricts1 ! rocks are (t5 trav]s$ by m or less v]tical dykes or ve9s ( igne\s matt]4 ,^! dykes appe> 9 "s cases to h be5 =m$ by ! fill+ up ( crevices f above--! liquid lava hav+ filt]$ d[nw>ds f an ov]fl[+ mass4 ,9 mo/ cases1 h[ev]1 ! lava has be5 inject$ f bel[1 & n unfrequ5tly ! 'dykes' seem to h be5 ! fe$]s f :i* lava-/reams h be5 suppli$--! fe$]s hav+ n[ become expos$ to ! light ( day ei!r by "s viol5t eruption :i* has torn ! rocks asund]1 or else by ! gradual we>+ away ( ! latt] by atmosph]ic & aque\s ag5cies4 ,,metamorphism4 #hc4 ,m5tion has already be5 made ( ! fact1 t ! heat$ matt]s eject$ f volcanoes1 or =cibly intrud$ into cracks1 crevices1 c41 occasionally alt] ! rocks ) :i* !y come 9 contact4 ,:5 ?is alt]ation has proce$$ s f> z to induce a cry/all9e or semi-cry/all9e "*1 ! rock s alt]$ is said to be metamorphos$4 ,metamorphism has likewise be5 produc$ by ! *emical action ( p]colat+ wat]1 :i* frequ5tly dissolves out c]ta9 m9]als1 & replaces ^! ) o!rs hav+ (t5 a v diff]5t *emical composition4 ,b metamorphism on ! l>ge scale--t is to say1 metamorphism :i* has affect$ wide areas1 su* z ! nor!rn ,highl&s ( ,scotl& & wide regions 9 ,sc&9avia1 or ! /ill va/] areas 9 ,nor? ,am]ica--has mo/ probably be5 effect$ bo? by ! ag5cy ( heat & *emical action1 at consid]able dep?s1 & "u great pressure4 ,:5 we obs]ve :at effect c be produc$ by heat ^u rocks1 "u little or no pressure1 & h[ wat] p]colat+ f above gradually *anges ! composition ( "s rock-masses1 we may readily believe t at great dep?s1 :]e ! heat is excessive1 su* metamorphic action mu/ (t5 be int5sifi$4 ,?us1 = example1 lime/one heat$ 9 ! usual way gives (f its c>bonic acid gas1 & is r$uc$ to quicklime2 b1 "u suffici5t pressure1 ?is gas is n evolv$1 ! lime/one becom+ conv]t$ into a cry/all9e m>ble4 ,"s cry/all9e lime/ones1 inde$1 h all ! appe>ance ( hav+ at "o "t be5 actually melt$ & squirt$ "u great pressure into seams & cracks ( ! surr\nd+ /rata4 ,heat$ wat] w\ld appe> to h be5 ! ag5t to :i* mu* ( ! metamorphism :i* affects ! rocky /rata mu/ be attribut$4 ,b ! mode or modes 9 :i* x has act$ are /ill some:at obscure2 z may be readily und]/ood :5 x is rememb]$ h[ difficult1 & (t5 h[ impossible x is to realise or reproduce 9 our laboratories ! conditions "u :i* deep-seat$ metamorphic action mu/ frequ5tly h tak5 place4 ,9 foliat$ rocks1 ! m9]als are *iefly qu>tz1 felsp>1 & mica1 talc1 or *lorite4 ,! +r$i5ts ( ^! m9]als und\bt$ly exi/$ 9 a diffus$ /ate 9 ! orig9al rocks1 & heat$ wat] *>g$ ) alkal9e c>bonates1 z x p]colat$ ?r\gh ! /rata1 ei!r along ! lay]s ( b$d+ or l9es ( cleavage1 sl[ly act$ ^u ^!1 dissolv+ & r$eposit+ !m1 & ?us induc+ segregation4 ,!re is e k9d ( gradation 9 metamorphism4 ,?us1 we f9d c]ta9 rocks :i* are b slightly alt]$--_! orig9al "* be+ /ill q app>5t2 :ile1 9 o!r cases1 ! orig9al "* is s entirely effac$ t we c only conjecture :at t may h be54 ,:5 we h a consid]able ?ickness ( metamorphic rocks :i* /ill exhibit m or less di/9ct traces ( b$d+1 l ! successive b$s ( gneiss1 mica-s*i/1 & qu>tz rock ( ! ,scotti% ,highl&s1 we c h>dly d\bt t ! n[ cry/all9e masses are m]ely highly alt]$ aque\s /rata4 ,b !re are cases :]e ev5 ! b$d+ becomes oblit]at$1 & x is !n mu* m difficult to det]m9e ! orig9 ( ! rocks4 ,?us1 we f9d b$d$ gneiss passes (t51 by ins5sible gradations1 into true amorph\s granite4 ,!re has be5 mu* diff]5ce ( op9ion z to ! orig9 ( granite--"s hold+ x to be an igne\s rock1 o!rs ma9ta9+ its metamorphic orig94 ,x is probably bo? igne\s & metamorphic1 h[ev]4 ,if we conceive ( c]ta9 aque\s rocks becom+ metamorphos$ into gneiss1 we may surely conceive ( ! metamorphism be+ /ill fur!r cont9u$ until ! mass is r$uc$ to a semi-fluid or pa/y condition1 :5 all trace ( foliation & b$d+ might readily disappe>1 & ! weight ( ! sup]9cumb5t /rata w\ld be suffici5t to =ce portions ( ! s(t5$ mass into cracks & crevices ( ! /ill solid rocks above & ar\nd x4 ,h5ce we might expect to f9d ! same mass ( granite pass+ gradually 9 "s places into gneiss1 & 9 o!r places protrud+ z ve9s & dykes into ! surr\nd+ rocks2 & ?is is precisely :at occurs 9 nature4 #hd4 ,m9]al ve9s h1 z a rule1 be5 =m$ by wat] deposit+ along ! walls ( fissures ! v>i\s matt]s :i* !y held 9 solution1 b c]ta9 k9ds ( ve9s 7su* z qu>tz ve9s 9 granite7 probably owe _! orig9 to *emical action :i* has induc$ ! qu>tz to segregate f ! rock mass4 ,"s h ma9ta9$ t ! metallic sub/ances met ) 9 _m ve9s owe _! deposition to ! action ( curr5ts ( voltaic electricity2 :ile o!rs h attribut$ _! pres5ce to sublimation f bel[1 ! metals hav+ be5 deposit$ 9 ! fissures v mu* z lead is deposit$ 9 ! *imney ( a leadmill4 ,b 9 _m cases !re seems little reason to d\bt t ! ores h m]ely be5 extract$ f ! rocks1 & re-deposit$ 9 fissures1 by wat]1 9 ! same way z ! o!r m9]als ) :i* !y are associat$4 ,,physiography4 #he4 ,d5udation4--,by ! comb9$ action ( all ! geological ag5cies :i* h be5 describ$ 9 ! prec$+ sections1 ! e>? has acquir$ its pres5t div]sifi$ surface4 ,valleys1 lacu/r9e holl[s1 table-l&s1 & m\nta9s h all be5 m or less sl[ly =m$ by ! =ces :i* we see ev5 n[ at "w 9 ! _w ar\nd u4 ,:5 we reflect ^u ! fact t all ! incl9$ /rata :i* crop out at ! surface ( ! gr\nd are b ! truncat$ portions ( b$s t 7 once cont9u\s1 & =m$ complete anticl9al ar*es or curves1 we mu/ be impress$ ) ! degree ( d5udation1 or we>+-away1 :i* ! solid /rata h exp]i5c$4 ,if we protract 9 imag9ation ! outcrop ( a giv5 set ( /rata1 we %all f9d !m curv+ upw>ds into ! air to a height (1 x may be1 hundr$s or ev5 ?\s&s ( feet1 be=e !y roll ov] to come d[n & fit on to ! truncat$ ends ( ! b$s on ! fur!r side ( ! anticl9e 7see figs4 #i & #aa1 pages #cc1 #cd74 ,dislocations or faults af=d fur!r /rik+ evid5ce 9 ! same direction4 ,sometimes ^! h displac$ ! /rata = hundr$s & ev5 ?\s&s ( feet--t is to say1 t a b$ occurr+ at1 = example1 a few feet f ! surface ^u "o side ( a fault1 has sunk hundr$s or ?\s&s ( feet on ! o!r side4 ,yet x (t5 happ5s t !re is no irregul>ity at ! surface to betray ! exi/5ce ( a dislocation4 ,! gr\nd may be flat z a b[l+-gre51 & yet1 ow+ to "s great fault1 ! rocks und]nea? "o end ( ! flat may be geologically _m hundr$ feet1 or ev5 y>ds1 high] or l[] ?an ! /rata und]nea? ! o!r end ( ! same level space4 ,:at has become ( ! miss+ /rata8 ,!y h be5 c>ri$ away gra9 by gra9 by ! d5ud+ =ces--by wea!r+1 ra91 fro/1 & fluviatile & m>9e action4 ,! :ole surface ( a c\ntry is expos$ to ! abrad+ action ( ! suba]ial =ces1 & has be5 c>v$ by !m into hills & valleys1 ! position ( :i* dep5ds p>tly ^u ! geological /ructure ( ! c\ntry1 & p>tly ^u ! texture & composition ( ! rocks4 ,! orig9al slope ( ! surface1 :5 x 0 fir/ elevat$ out ( ! sea1 w\ld be det]m9$ by ! action ( ! subt]rane\s =ces--! dom9ant p>ts1 :e!r table-l&s or undulat+ ridges1 =m+ ! c5tres f :i* ! wat]s w\ld beg9 to fl[4 ,aft] ! l& _h be5 subject$ = _m long ages to ! we>+ action ( ! d5ud+ ag5ts1 x is evid5t t ! s(t] rocks--^? :i* 7 lea/ capable ( )/&+ wea!r+ & erosion--w\ld be m worn away ?an ! less easily decompos$ masses4 ,! latt] w\ld1 !re=e1 t5d to =m elevations1 & ! =m] holl[s4 ,?is is precisely :at we f9d 9 nature4 ,! great majority ( isolat$ hills & hilly tracts owe _! exi/5ce z su* m]ely to ! fact t !y are =m$ ( m durable mat]ials ?an ! rock-masses by :i* !y are surr\nd$4 ,:5 a l9e ( dislocation is visible at ! surface1 x is simply because rocks ( unequal durability h be5 br\ght into juxtaposition4 ,! m easily d5ud$ /rata h wa/$ away to a great] ext5t ?an ! t\gh] masses on ! o!r side ( ! dislocation4 ,ne>ly all elevations1 !re=e1 may be look$ ^u z monum5ts ( ! d5udation ( ! l&2 !y =m hills = ! simple reason t !y h be5 bett] able to )/& ! attacks ( ! d5ud+ ag5ts ?an ! rocks out ( :i* ! holl[s h be5 erod$4 #hf4 ,to ?is g5]al rule !re are exceptions1 ! mo/ obvi\s be+ hills & m\nta9s ( volcanic orig91 su* z ,hecla1 ,etna1 ,vesuvius1 c41 &1 on a l>g] scale1 ! rocky ridge ( ! ,&es4 ,aga91 x is evid5t t ! great m\nta9-*a9s ( ! _w are due 9 ! fir/ place to upheaval2 b ^! m\nta9s1 z we n[ see !m--peaks1 cliffs1 precipices1 gorges1 rav9es--h be5 c>v$ out ( ! solid block1 z x 71 by ! ceaseless action ( ! suba]ial =ces4 ,! direction ( riv]-valleys has 9 l mann] be5 det]m9$ 9 ! fir/ place by ! orig9al slope ( ! l&2 b ! deep dells1 ! broad valleys & /ra?s1 h all be5 scoop$ out by runn+ wat]4 ,! nor!rn ,highl&s ( ,scotl&1 = example1 evid5tly =m$ at "o "t a broad table-l&1 elevat$ above ! level ( ! sea by ! subt]ranean =ces4 ,out ( ?is old table-l& ! d5ud+ ag5ts1 act+ ?r\gh untold ages1 h c>v$ out all ! num]\s rav9es1 gl5s1 & valleys1 ! int]v5+ ridges left beh9d n[ =m+ ! m\nta9s4 ,x is true t n[ & aga9 /reams are f\nd fl[+ 9 ! direction ( a fault1 b t is simply because ! dislocation is a l9e ( weakness1 along :i* x is easi] = ! d5ud+ =ces to act4 ,= "o fault t we f9d runn+ p>allel to ! c\rse ( a riv]1 we may obs]ve hundr$s cutt+ across its c\rse at all angles4 ,! great rocky bas9s occupi$ by lakes1 :i* are s abundant 9 ! m\nta9\s di/ricts ( temp]ate regions & 9 nor!rn latitudes1 are believ$ to h be5 excavat$ by ! erosive p[] ( glaci]-ice2 & !y po9t1 !re=e1 to a "t :5 our hemisph]e mu/ h be5 subject$ to a climate sev]e en\gh to n\ri% massive glaci]s 9 ! ,briti% ,isl&s & simil> latitudes4 ,x may be conclud$ t ! pres5t physiography ( ! l& is proximately due solely to ! action ( ! d5ud+ ag5ts--ra91 fro/1 riv]s1 & ! sea4 ,b ! l9es along :i* ^! ag5ts act ) greate/ int5sity h be5 det]m9$ 9 ! fir/ place by ! subt]ranean =ces :i* upheav$ ! solid cru/ into great table-l&s or m\nta9 undulations4 ,bo? ! remote & ! proximate causes ( ! e>?'s surface-features1 h[ev]1 h act$ 9 conc]t & contemporane\sly1 = no soon] w\ld new l& em]ge above ! sea-level ?an ! break]s w\ld assail x1 & all ! =ces ( ! atmosph]e w\ld be br\ght to be> ^u x--ra91 fro/1 & riv]s--s t ! beg9n+ ( ! sculptur+ ( hill & valley dates back to ! p]iod :5 ! pres5t l&s 7 sl[ly em]g+ f ! ocean4 ,s great is ! d5udation ( ! l&1 t 9 process ( "t ! :ole w\ld be plan$ d[n to ! level ( ! sea1 if x 7 n = ! subt]ranean =ces1 :i* f "t to "t depress & elevate diff]5t portions ( ! e>?'s cru/4 ,x c be prov$ t /rata miles 9 ?ickness h be5 remov$ bodily f ! surface ( our own c\ntry by ! seem+ly feeble ag5ts ( d5udation4 ,all ! d5ud$ mat]ial--mud1 s&1 & gravel--c>ri$ d[n into ! sea has be5 re-arrang$ into new b$s1 & ^! h ev] & anon be5 pu%$ up to ! light ( day1 & sc>p$ & *annell$ by ! d5ud+ =ces1 ! result+ detritus be+ swept d[n z be=e into ! sea1 to =m fre% deposits1 & s on4 ,x foll[s1 !re=e1 t ! pres5t arrangem5t ( l& & sea has n always exi/$4 ,!re 0 a "t be=e ! pres5t di/ribution ( l& obta9$1 & a "t w yet arrive :51 aft] inf9ite modifications ( surface & level1 ! cont95ts & isl&s may be entirely re-arrang$1 ! sea replac+ ! l&1 & vice v]sa4 ,to trace ! hi/ory ( su* *anges 9 ! pa/ is "o ( ! great aims ( ! sci5tific geologi/4 ,,palaeontology4,f ,f ,palaios1 anci5t1 onta1 be+s1 & logos1 a disc\rse4 #hg4 ,fossils4--,9 our description ( rock-masses1 & aga9 9 our acc\nt ( geological ag5cies1 we ref]r$ to ! fact t c]ta9 rocks are compos$ 9 l>ge measure1 or exclusively1 ( animal or vegetable organisms1 or ( bo? toge!r2 & we saw t analog\s organic =mations 7 be+ accumulat$ at ! pres5t "t4 ,b we h def]r$ to ?is place any special acc\nt ( ! organic rema9s :i* are entomb$ 9 rocks4 ,fossils1 z ^! are call$1 consi/ g5]ally ( ! h>d] & m durable p>ts ( animals & plants1 su* z bones1 %ells1 tee?1 se$s1 b>k1 & ligne\s tissues1 c4 ,b x is usual to ext5d ! t]m fossil to ev5 ! ca/s or impressions ( su* rema9s1 & to foot-m>ks & tracks1 :e!r ( v]tebrates1 molluscs1 cru/aceans1 or annelids4 ,! organic rema9s met ) 9 ! rocks h usually und]gone "s *emical *ange4 ,!y h become petrifi$ :olly or 9 "p4 ,! gelat9e :i* orig9ally gave flexibility to "s ( !m has disappe>$1 & ev5 ! c>bonate & phosphate ( lime ( ! h>d] p>ts h frequ5tly be5 replac$ by o!r m9]al matt]1 by fl9t1 pyrites1 or ! l4 ,s p]fect is ! petrifaction 9 _m cases1 t ! mo/ m9ute /ructures h be5 entirely pres]v$--! orig9al matt] hav+ be5 replac$ atom by atom4 ,z a rule1 fossils occur mo/ abundantly & 9 ! be/ /ate 9 clay-rocks1 l %ale2 :ile 9 por\s rocks1 l s&/one1 !y are g5]ally poorly pres]v$1 & n ( s frequ5t occurr5ce4 ,"o reason = ?is is1 t clay-rocks are mu* less p]vi\s ?an s&/one1 & _! imb$d$ fossils h consequ5tly escap$ 9 great] measure ! solv5t p[]s ( p]colat+ wat]4 ,b !re are o!r reasons = ! comp>ative paucity ( fossils 9 ar5ace\s /rata1 z we %all see pres5tly4 #hh4 ,pro(s ( v>i$ ,physical ,conditions4--,organic rema9s are ei!r ( t]re/rial1 fre%-wat]1 or m>9e orig91 & !y are !re=e ( ! utmo/ value to ! geologi/ 9 deciph]+ ! hi/ory ( ^? great *anges :i* h culm9at$ 9 ! pres5t4 ,b we c g a /ep fur!r ?an ?is4 ,we "k t at ! pres5t day ! di/ribution ( animal & vegetable life is due to a v>iety ( causes--to climatic & physical conditions4 ,! creatures inhabit+ arctic & temp]ate regions contra/ /rongly ) ^? t t5ant ! tropics4 ,s also we obs]ve a *ange 9 animal & vegetable =ms z we asc5d f ! l[ gr\nds ( a c\ntry to its m\nta9 heights4 ,simil> *anges take place 9 ! sea4 ,! animals & plants ( littoral regions diff] f ^? ^: habitat is 9 deep] wat]4 ,n[1 ! fossilif]\s /rata ( our globe af=d simil> pro(s ( v>y+ climatic & physical conditions4 ,!re are littoral deposits & deep-sea accumulations3 ! =m] are g5]ally co>se-gra9$ 7conglom]ates1 grit1 & s&/one72 ! latt] are = ! mo/ "p f9]-gra9$ 7clay1 %ale1 lime/one1 *alk1 c472 & bo? in%ore & deep-wat] =mations h ea* _! peculi> organic rema9s4 ,aga91 we "k t "s p>ts ( ! sea-bottom are n s prolific 9 life z o!rs--:]e1 = example1 any consid]able deposit ( s& is tak+ place1 or :]e s$im5t is be+ con/antly wa%$ to & fro ^u ! bottom1 %ells & o!r creatures d n appe> 9 su* numb]s z :]e !re is less commotion1 & a f9] & m equable deposit is tak+ place4 ,x is p>tly = ! same reason t c]ta9 rocks are m b>r5 ( organic rema9s ?an o!rs4 #hi4 ,fossil ,g5]a & ,species frequ5tly ext9ct4--,x might p]haps at fir/ be suppos$ t simil> rocks w\ld conta9 simil> fossils4 ,= example1 we might expect t =mations resembl+ 9 _! orig9 ^? :i* are n[ =m+ 9 our coral seas w\ld also1 l ! latt]1 conta9 corals 9 abundance1 ) "s comm+l+ ( %ells1 cru/aceans1 fi%1 c41 su* z are peculi> to ! w>m seas 9 :i* corals fl\ri%4 ,& ?is 9 "s measure holds good4 ,b :5 we exam9$ c>efully ! fossils 9 c]ta9 ( ! lime/ones ( our own c\ntry1 we %\ld f9d t :ile ! same great ord]s & classes 7 actually pres5t1 yet ! g5]a & species 7 frequ5tly entirely diff]5t2 & n only s1 b t (t5 none ( ^! 7 n[ liv+ on ! e>?4 ,moreov]1 if we ext5d$ our rese>*1 we %\ld soon discov] t simil> wide diff]5ces actually obta9$ betwe5 _m ( ! lime/ones !mselves & o!r fossilif]\s /rata ( our c\ntry4 #ij4 ,fossilif]\s ,/rata ( ,diff]5t ,ages4--,ano!r fact w\ld also gradually dawn ^u u--?is1 namely1 t 9 c]ta9 rocks ! fossils dep>t mu* m widely f analog\s liv+ =ms1 ?an ! organic rema9s 9 c]ta9 o!r rocks d4 ,! cause ( ?is lies 9 ! fact t ! fossilif]\s /rata are ( diff]5t ages2 !y h n all be5 =m$ at approximately ! same "t4 ,on ! contr>y1 !y h be5 sl[ly amass$1 z we h se51 dur+ a long succession ( eras4 ,:ile !y h be5 accumulat+1 great vicissitudes 9 ! di/ribution ( l& & sea h tak5 place1 climates h frequ5tly alt]$1 & ! :ole organic life ( ! globe has sl[ly *ang$ aga9 & aga9--successive races ( plants & animals fl\ri%+ ea* = its allott$ p]iod1 & !n becom+ ext9ct = ev]4,g ,?us1 /rata =m$ at approximately ! same "t conta9 g5]ally ! same fossils2 :ile1 on ! o!r h&1 s$im5t>y deposits accumulat$ at diff]5t p]iods are *>g$ ) diff]5t fossils4 ,fossils 9 ?is way become invaluable to ! geologi/4 ,!y enable him to id5tify =mations 9 sep>ate di/ricts1 & to assign to !m _! relative antiquity4,h ,if1 = example1 we h a s]ies ( =mations1 ,a1 ,b1 ,c1 pil$ "o on ! top ( ! o!r1 ,a be+ ! l[e/1 & ,c ! highe/1 & ea* *>g$ ) its own peculi> fossils1 we may comp>e ! fossils met ) 9 o!r sets ( /rata ) ! organic rema9s f\nd 9 ,a1 ,b1 ,c4 ,%\ld ! =m] be f\nd to correspond ) ! fossil cont5ts ( ,b1 we conclude t ! rocks 9 :i* !y occur are approximately ( contemporane\s orig9 ) ,b1 ev5 al?\gh ! equival5ts ( ! =mations ,a & ,c %\ld be entirely want+4 ,fur!r1 we soon le>n t ! ord] ( ! s]ies ,a1 ,b1 ,c1 is nev] inv]t$4 ,if ,a be ! l[e/1 & ,c ! highe/ /ratum 9 "o place1 x is q c]ta9 t ! same ord] ( succession w obta9 :]ev] ! equival5ts ( ^! /rata happ5 to occur toge!r4 ,b ! succession ( /rata is n inv>iably ! same all ! _w ov]2 9 "s c\ntries1 we may h doz5s ( sep>ate =mations pil$ "o on ! top ( ! o!r2 9 o!r c\ntries1 _m memb]s ( ! s]ies are abs5t2 9 brief1 blanks 9 ! succession are ( con/ant occurr5ce4 ,b by dovetail+1 z x 71 all ! =mations kn[n to u1 we are enabl$ to =m a m or less complete s]ies ( rocks arrang$ 9 ! ord] ( _! age4 ,a little reflection w s]ve to %ew t ! p>tial mode 9 :i* ! /rata are di/ribut$ ov] ! globe arises *iefly f two causes4 ,we h to rememb]1 fir/1 t ! deposits !mselves 7 laid d[n only "h & !re 9 irregul> spreads & pat*es--opposite ! m\?s ( riv]s1 at v>i\s po9ts along ! anci5t coa/-l9es1 & ov] c]ta9 areas 9 ! deep] abysses ( ! ocean--! co>s] accumulations be+ ( mu* less ext5t ?an ^? =m$ ( f9] mat]ials4 ,&1 second1 we mu/ n =get ! int5se d5udation :i* !y h exp]i5c$1 s t miles & miles ( /rata :i* once exi/$ h be5 swept away1 & _! mat]ials built up into new =mations4 ,g ,to ?is !re are "s exceptions4 ,c]ta9 small =am9if]s1 = example1 met ) 9 "s ( ! olde/ =mations1 d n seem to diff] f species :i* are /ill liv+4 ,! g5us ,l+ula 7,mollusca7 has also come d[n f remote/ ages1 hav+ outliv$ all its e>li] associates4 ,h ,?is holds /rictly true1 h[ev]1 only 9 reg>d to comp>atively limit$ areas4 ,! /ud5t mu/ rememb] t /rata occurr+ 9 widely sep>ate regions ( ! e>?1 ev5 al?\gh !y conta9 v mu* ! same assemblage ( fossils1 are n necess>ily contemporane\s1 9 ! /rict mean+ ( ! ^w2 = ! fauna & flora 7! animal & plant life7 may h di$ out1 & become replac$ by new =ms m rapidly 9 "o place ?an ano!r4 ,! t]m 'contemporane\s1' !re=e1 is a v lax "o1 & may sometimes gr\p toge!r deposits :i*1 = aught t we c tell1 may really h be5 accumulat$ at widely sep>at$ times4 #ia4 ,gradual ,ext9ction ( ,species4--,:5 a suffici5t numb] ( fossils has be5 dilig5tly comp>$1 we discov] t ^? 9 ! y\ng] /rata approa* mo/ ne>ly to ! pres5t liv+ =ms1 & t ! old] ! /rata are1 ! m widely d _! organic rema9s dep>t f exi/+ types ( animals & plants4 ,we may notice also1 t :5 a s]ies ( b$s graduate up into ea* o!r1 s t no /rongly m>k$ l9e sep>ates ! ov]ly+ f ! und]ly+ /rata1 !re is also a simil> gradation among/ ! fossils4 ,! fossils 9 ! highe/ b$s may diff] entirely f ^? 9 ! l[e/2 b 9 ! middle b$s !re is an int]m+l+ ( =ms4 ,9 %ort1 x is evid5t t ! creatures gradually became ext9ct1 & 7 j z gradually replac$ by new =ms1 until a "t came :5 all ! species t 7 liv+ :ile ! l[e/ b$s 7 be+ amass$1 at la/ di$ out1 & a complete *ange 0 effect$4 #ib4 ,pro(s ( ,cosmical ,*anges ( ,climate4--,f ! prec$+ rem>ks x w be also app>5t t fossils tea* u mu* reg>d+ ! climatology ( pa/ ages4 ,!y tell u h[ ! area ( ! ,briti% ,isl&s has exp]i5c$ _m vicissitudes ( climate1 sometimes rejoic+ 9 a w>m or almo/ tropical temp]ature1 at o!r times visit$ ) a climate z sev]e z is n[ exp]i5c$ 9 arctic & ant>ctic regions4 ,n only s1 b we le>n f fossils t ,gre5l& once support$ myrtles & o!r plants :i* are n[ only f\nd gr[+ "u mild & g5ial climatic conditions2 :ile1 on ! o!r h&1 rema9s ( arctic mammals are met ) 9 ! s\? ( ,france4 ,su* great *anges ( climate are due1 accord+ to ,mr ,croll1 to v>iations 9 ! ecc5tricity ( ! e>?'s orbit comb9$ ) ! precession ( ! equ9ox4 ,x is well kn[n t ! orbit ( our e>? becomes mu* m elliptical at c]ta9 irregul>ly recurr+ p]iods ?an x is at pres5t4 ,dur+ a p]iod ( extreme ellipticity1 ! e>? is1 ( c\rse1 mu* fur!r away f ! sun 9 aphelion,i ?an x is at a "t ( mod]ate ellipticity1 :ile1 9 p]ihelion1,j x is consid]ably ne>]4 ,n[1 let u suppose t1 at a "t :5 ! ellipticity is great1 ! movem5t kn[n z ! precession ( ! equ9ox has *ang$ ! incid5ce ( our seasons1 s t our summ] happ5s 9 p]ihelion & n 9 aphelion1 :ile t ( ! s\!rn hemisph]e occurs 9 aphelion1 & n1 z at pres5t1 9 p]ihelion4 ,"u su* conditions1 ! climate ( ! globe w\ld exp]i5ce a complete *ange4 ,9 ! nor!rn hemisph]e1 s long & int5sely cold w\ld ! w9t] be1 t all ! moi/ure t fell w\ld fall z ra91 & al?\gh ! summ] w\ld be v w>m1 x w\ld nev]!less be v %ort1 & ! heat !n receiv$ w\ld be insuffici5t to melt ! sn[ & ice :i* _h accumulat$ dur+ ! w9t]4 ,?us gradually sn[ & ice w\ld cov] all ! l&s d[n to temp]ate latitudes4 ,9 ! s\!rn hemisph]e1 ! rev]se ( all ?is w\ld obta94 ,! w9t] !re w\ld be %ort & mild1 & ! summ]1 al?\gh cool1 w\ld be v long4 ,b su* *anges w\ld br+ into action a :ole s]ies ( physical ag5cies1 e "o ( :i* w\ld t5d /ill fur!r to increase ! diff]5ce betwe5 ! climates ( ! two hemisph]es4 ,ow+ to ! va/ accumulation ( sn[ & ice 9 ! nor!rn hemisph]e1 ! diff]5ce ( temp]ature betwe5 equatorial & temp]ate & pol> regions w\ld be great] 9 t hemisph]e ?an 9 ! s\!rn4 ,h5ce ! w9ds bl[+ f ! nor? w\ld be m p[]ful ?an ^? com+ f ! s\!rn & w>m] hemisph]e1 & consequ5tly ! w>m wat] ( ! tropics w\ld necess>ily be impell$ into ! s\!rn ocean4 ,?is w\ld t5d /ill fur!r to l[] ! temp]ature ( our hemisph]e1 :ile1 at ! same "t1 x w\ld raise correspond+ly ! temp]ature at our antipodes4 ,! g5]al result w\ld be1 t 9 our hemisph]e ice & sn[ w\ld cov] ! gr\nd d[n to l[ temp]ate latitudes--! ,briti% ,isl&s be+ completely smo!r$ "u a great sea ( conflu5t glaci]s4 ,9 ! s\!rn hemisph]e1 on ! contr>y1 a k9d ( p]5nial summ] w\ld reign ev5 up to ! pole4 ,su* conditions w\ld la/ = "s t5 or twelve ?\s& ye>s1 & !n1 ow+ to ! precession ( ! equ9ox1 a complete *ange w\ld come ab\t--! ice-cap w\ld disappe> f ! nor?1 & be replac$ by cont9u\s summ]1 :ile at ! same "t an excessively sev]e or glacial climate w\ld *>act]ise ! s\?2 & su* great *anges w\ld occur sev]al times dur+ ea* prolong$ epo* ( great ecc5tricity4 ,?is1 9 few words1 is an outl9e ( ,mr ,croll's !ory4 ,t !ory is at pres5t sub judice1 b !re c be no d\bt t x gives a reasonable explanation ( _m geological facts :i* h hi!rto be5 inexplicable4 ,( c\rse1 x is n ma9ta9$ t all *anges ( climate are due directly or indirectly to a/ronomical causes4 ,local *anges ( climate--*anges affect+ limit$ regions--may be induc$ by mutations ( l& & sea1 result+ 9 ! p>tial deflection ( ocean curr5ts1 :i* are ! *ief second>y means employ$ by nature = ! di/ribution ( heat ov] ! globe's surface4 ,i ,apo1 away f2 helios1 ! sun4 ,j ,p]i1 r\nd ab\t or ne> by2 helios1 ! sun4 ,f :at has be5 /at$ 9 ! =ego+ p>agraphs1 x is cle> t 9 our endeav\rs to deciph] ! geological hi/ory ( our planet1 palaeontological mu/ g h& 9 h& ) /ratigraphical evid5ce4 ,we may inde$ le>n mu* f ! mode ( arrangem5t ( ! rocks !mselves4 ,b ! te/ ( sup]position does n always avail u4 ,x is (t5 h>d1 & sometimes q impossible1 to tell f /ratigraphical evid5ce :i* are ! old] rocks ( a di/rict4 ,9 ! abs5ce ( fossils we mu/ frequ5tly be 9 d\bt4 ,b physical evid5ce alone w (t5 af=d u mu* & v>i$ in=mation4 ,x w %ew u :at 0 l& & :at sea at "s =m] p]iod2 x w indicate to u ! sites ( anci5t igne\s action2 x w tell u ( riv]s1 & lakes1 & seas :i* h long s9ce pass$ away4 ,nay1 9 "s cases1 x w ev5 conv9ce u t c]ta9 great climatic *anges h tak5 place1 by po9t+ out to u ! m>k+s1 & debris1 & w&]$ blocks :i* are ! sure traces ( ice action1 :e!r ( glaci]s or iceb]gs4 ,! results obta9$ by comb9+ physical & palaeontological evid5ce =m :at is t]m$ ,hi/orical ,geology4 ,,hi/orical ,,geology4 #ic4 ,! fossilif]\s /rata1 z !y are g5]ally t]m$1 h be5 *ronologically arrang$ 9 a s]ies ( =mations1 ea* ( :i* is *>act]is$ by its own peculi> suites ( fossils4 ,_! relative age has be5 det]m9$1 z we h indicat$ above1 by _! fossils1 & also by c]ta9 physical te/s1 ! *ief ( ^! be+ sup]position4 ,x holds inv>iably true t a =mation1 ,a1 f\nd re/+ ^u ano!r s]ies ( /rata1 ,b1 w always occur 9 precisely ! same position1 :]ev] ^! two deposits occur toge!r4 ,if ,b %\ld appe> 9 "s place z re/+ ^u ,a1 we may be sure t ! b$s h be5 inv]t$ dur+ ! contortion ( ! /rata consequ5t ^u subt]ranean action 7see fig4 #aa1 page #cd74 ,aga91 ano!r useful te/ ( ! relative age ( /rata lies 9 ! circum/ance t "o is (t5 made up or conta9s fragm5ts ( ! o!r4 ,9 ?is case1 !n1 x is q cle> :i* is ! m rec5t accumulation4 ,^! te/s h n[ be5 appli$ to ! /rata 9 _m p>ts ( ! _w1 & ! result is t geologi/s h be5 able to arrive at a *ronological arrangem5t or classification1 & s to con/ruct a table %ew+ ! relative position :i* w\ld be occupi$ by all ! diff]5t =mations1 if ^! occurr$ toge!r 9 "o place4 ,9 ! ,briti% ,isl&s ! long s]ies ( /rata is well develop$1 b _m ( ! =mations are mu* m meagrely repres5t$ ?an _! equival5ts 9 o!r c\ntries4 ,b ev5 :5 we attempt to fill up ! blanks 9 our own s]ies by dovetail+ ) !m ! /rata ( =eign c\ntries1 !re yet rema9 num]\s breaks 9 ! succession1 po9t+ to ! fact t ! /ony record is a v fragm5t>y "o at ! be/4 ,no d\bt !re are _m l>ge tracts ( ! e>?'s surface :i* h n yet be5 inve/igat$1 & :5 ^! are kn[n we may hope to h our k greatly increas$4 ,b no "o :o reflects ^u ! mode ( orig9 ( ! fossilif]\s /rata1 & ! wond]ful mutations :i* ! e>? has und]gone1 c reasonably anticipate t a p]fect & complete record ( ! geological hi/ory ( our planet %all ev] be compil$ f ! brok5 & fragm5t>y te/imony ( ! rocks4 #id4 ,! foll[+ table gives ! names ( ! diff]5t =mations arrang$ 9 ! ord] ( _! sup]position1 ! y\nge/ be+ at ! top1 & ! olde/ kn[n at ! bottom3 ,,iv4 ,,po/-,,t]ti>y ,,or ,,quat]n>y-- ,hi/orical or ,rec5t4 ,plei/oc5e4 ,,iii4 ,,t]ti>y ,,or ,,ca9ozoic-- ,plioc5e4 ,mioc5e4 ,eoc5e4 ,,ii4 ,,second>y ,,or ,,mesozoic-- ,cretace\s4 ,jurassic4 ,triassic4 ,i4 ,,prim>y ,,or ,,palaeozoic-- ,p]mian4 ,c>bonif]\s4 ,devonian & ,old ,r$ ,s&/one4 ,silurian4 ,cambrian4 ,laur5tian or ,pre-,cambrian4 #ie4 ,! ,,prim>y =mations are s call$ because !y are ! olde/ kn[n to u3 !y are n necess>ily ! fir/-=m$ aque\s deposits4 ,dr ,hutton said truly3 ,!re is no trace ( a beg9n+1 & no signs ( an end4 ,9 ! ,,prim>y or ,,palaeozoic 7anci5t-life7 =mations are f\nd ! e>lie/ traces ( life4 ,! =ms z a rule dep>t v widely f ^? ) :i* we are acqua9t$ n[4 ,! ,laur5tian rocks h yield$ only "o fossil--a l>ge =am9if] nam$ ,eozoon ,canad5se4 ,! ,cambrian =mation conta9s b few fossils--cru/aceans1 molluscs1 zoophytes1 & worm-tracks4 ,! ,silurian /rata are (t5 abundantly fossilif]\s4 ,all ! great classes ( inv]tebrates are repres5t$1 & fi% rema9s also occur4 ,! ,devonian & ,old ,r$ ,s&/one are also *>act]is$ by ! pres5ce ( an abundant fauna4 ,9 ! ,old ,r$ ,s&/one are num]\s fi% rema9s2 x appe>s to h be5 an e/u>9e or lacu/r9e deposit2 ! ,devonian1 on ! o!r h&1 0 m>9e1 l ! ,silurian & ,cambrian4 ,! ,c>bonif]\s =mation is ! *ief repository ( coal 9 ,brita94 ,x consi/s ( t]re/rial1 fre% or bracki% wat]1 & m>9e deposits4 ,! fauna & flora ( ! ,p]mian1 :i* is p>tly a m>9e & p>tly a fre%-wat] =mation1 are alli$1 ^u ! :ole1 to ^? ( ! ,c>bonif]\s1 b (f] at ! same "t _m contra/s4 #if4 ,! ,,second>y ,,or ,,mesozoic 7middle-life7 =mations conta9 assemblages ( fossils :i* d n dep>t s widely f analog\s liv+ =ms z ^? belong+ to ,palaeozoic times4 ,! ,triassic /rata yield abundance ( rock-salt4 ,9 ,brita9 !y conta9 v few fossils1 b ^! are m abundant 9 ! ,triassic deposits ( =eign c\ntries4 ,! olde/ kn[n mammals fir/ appe> 9 ?is =mation4 ,! ,jurassic =mation is v highly fossilif]\s4 ,x is di/+ui%$ by ! occurr5ce ( num]\s reptilian rema9s4 ,ne>ly all ! b$s ( ?is =mation are m>9e1 b !re are associat$ ) ^! ! rema9s ( a =e/ or old l& surface1 & a consid]able accumulation ( e/u>9e or fre%-wat] deposits2 impure coals also occur 9 ?is =mation4 ,! ,cretace\s /rata are almo/ :olly m>9e1 & *iefly ( deep-wat] orig94 ,b "s l&-plants are f\nd1 *iefly f]ns1 conif]s1 & cycads4 ,ne> ! base ( ! =mation occurs a great riv] deposit 7,weald clay7 ) num]\s rema9s ( reptiles4 #ig4 ,among ! olde/ /rata ( ! ,,t]ti>y or ,,ca9ozoic 7rec5t-life7 division we meet ) ! dawn ( ! exi/+ /ate ( ! te/ace\s fauna--! ,eoc5e 7eos1 dawn1 & ka9os1 rec5t7 conta9+ ?ree & a half p] c5t4 ( rec5t species among its %ells4 ,! proportion ( rec5t species increases 9 ! ,mioc5e 7meion1 less1 & ka9os1 rec5t71 al?\gh ! majority ( ! molluscs entomb$ 9 t =mation belong to ext9ct species4 ,9 ! ,plioc5e 7pleion1 m1 & ka9os1 rec5t71 h[ev]1 ! ext9ct species are 9 a m9ority4 ,! ,,po/-,,t]ti>y or ,,quat]n>y division comprises ! conclud+ *apt]s ( geological hi/ory4 ,! ,plei/oc5e 7plei/os1 mo/1 & ka9os1 rec5t7 conta9s no ext9ct species ( %ells1 b a numb] ( ext9ct mammalia4 ,9 ! ,rec5t deposits all ! species ( animals & plants are liv+4 ,! ,t]ti>y & ,quat]n>y =mations are p>tly ( m>9e & p>tly ( t]re/rial & fre%-wat] orig94 ,at ! close ( ! ,t]ti>y p]iod ! 'glacial epo*' ( ,plei/oc5e times began1 & ! ,briti% ,isl&s & a l>ge "p ( nor!rn ,europe & ,nor? ,am]ica 7 !n cas$ 9 sn[ & ice4 ,traces ( glacial conditions h also be5 met ) 9 ! ,eoc5e & ,mioc5e4 ,! evid5ce furni%$ by ,palaeozoic & ,mesozoic =mations po9ts *iefly to mild1 g5ial1 & sometimes tropical conditions4 ,b traces ( ice action are occasionally not$ 7namely1 9 ! ,silurian1 ,old ,r$ ,s&/one1 ,c>bonif]\s1 ,p]mian1 & ,cretace\s =mations71 po9t+1 p]haps1 9 "s ( ! cases1 to =m] alt]nations ( cold & w>m p]iods4 ,inde$1 ! belief is n[ ga9+ gr\nd1 t ! s-call$ glacial epo* ( ,plei/oc5e times 0 n "o long cont9u\s age ( ice1 b r consi/$ ( an alt]nation ( w>m & cold p]iods4 ,& x is n improbable1 b highly likely1 t simil> alt]nations ( climate h happ5$ dur+ e p]iod ( great ecc5tricity ( ! e>?'s orbit4 ,,que/ions4 ,section #a4 ,:at is ,geology8 #b4 ,def9e ! t]m rock4 ,h[ _m classes ( rock are !re8 #c1 #d1 #e4 ,into :at gr\ps are ! me*anically =m$ rocks divid$8 ,def9e ! t]ms conglom]ate1 s&/one1 & %ale4 #f4 ,:at is ! nature ( ! rocks belong+ to ! ,a]ial or ,eolian gr\p8 #g4 ,give an example ( a *emically =m$ rock4 #h4 ,give examples ( organically d]iv$ rocks4 #i4 ,:at k9ds ( rocks are embrac$ by ! ,metamorphic class8 #aj4 ,:at are igne\s rocks8 #ab4 ,:at is ! m9]alogical composition ( granite8 #ac4 ,:at is meant by a m9]al8 #ad4 ,"n five m9]als :i* d n conta9 oxyg54 ,:]e does fluor-sp> occur8 ,:at is ! elem5t t ent]s mo/ l>gely into ! composition ( ! e>?'s cru/8 #ae4 ,"n ! =ms "u :i* ! m9]al qu>tz occurs4 ,"n "s ( ! oxides ( iron4 ,:at is iron pyrites8 #af4 ,"n two sulphates4 ,"n two c>bonates4 ,"n "s ( ! silicates4 ,9 :at k9ds ( rock is augite f\nd8 ,:]e does x nev] occur8 ,9 :at k9ds ( rock does hornbl5de usually occur8 ,m5tion ?ree species ( felsp>4 ,:at is "o ( ! mo/ di/+ui%+ *>act]i/ics ( mica8 ,"n ?ree silicates ( magnesia4 ,m5tion "s ( _! di/+ui%+ peculi>ities4 ,:]e d zeolites commonly occur8 #ag4 ,:at is a qu>tzose conglom]ate8 ,:at is a calc>e\s conglom]ate8 #ah4 ,:at is grit8 ,:at is free/one8 ,to :at are ! v>i\s col\rs ( s&/one due8 ,:at is %ale8 #ai4 ,"n "s typical ,eolian rocks1 & tell :]e !y occur4 #bj4 ,h[ d /alactites & /alagmites occur8 ,:at is silice\s s9t]1 & h[ does x occur8 ,h[ does rock-salt occur8 #ba4 ,m5tion "s ( ! v>ieties ( lime/one4 ,:at is corn/one8 ,:at is ! composition ( dolomite8 #bb4 ,"n "s ( ! v>ieties ( coal4 #bc4 ,:at is qu>tzite8 #bd4 ,describe clay-slate4 #be4 ,m5tion "s alt]$ lime/ones4 #bf4 ,:at are s*i/s8 ,"n & give ! m9]alogical composition ( ?ree s*i/s4 #bg4 ,:at is ! g5]al "* ( metamorphic rocks8 #bh4 ,h[ w\ld y classify granite8 #bi4 ,:at is ! m9]alogical composition ( sy5ite & diorite8 #cj4 ,h[ d we di/+ui% ! two gr\ps into :i* igne\s rocks are subdivid$8 ,:at is meant by ! t]ms amygdaloidal & porphyritic8 #ca4 ,"n "s rocks t belong to ! acidic gr\p4 ,:at is qu>tz-porphyry8 #cb4 ,give examples ( augitic igne\s rocks4 ,"n a hornbl5dic igne\s rock4 #cc4 ,:at are fragm5tal igne\s rocks8 ,:at is ! diff]5ce betwe5 trappean breccia & trappean conglom]ate8 #cd4 ,:at is meant by ! t]ms /ratum1 /rata1 & /ratifi$8 ,:at is ! diff]5ce betwe5 lam9ation & b$d+8 ,:at is a section8 #ce4 ,:at is false b$d+8 #cf4 ,briefly describe ! g5]al appe>ance ( mud-cracks & ra9-pr9ts1 & say h[ ^! h be5 =m$4 #cg4 ,:at is meant by a succession ( /rata8 #ch4 ,:i* k9ds ( /ratifi$ rocks g5]ally h ! greate/ ext5sion8 #ci4 ,h[ d b$s t]m9ate8 #dj4 ,h[ may planes ( b$d+ sometimes indicate a break 9 ! succession ( /rata8 #da4 ,:at is ! nature ( jo9ts8 ,:at are ma/]-jo9ts1 & :at is _! probable cause8 #db4 ,:at is cleavage1 & :at is its effect ^u ! b$d+ ( rocks8 #dc4 ,:at is foliation8 #dd4 ,give examples ( concretion>y rocks4 ,:at is ! nature ( *]t & fl9t nodules8 #de4 ,def9e ! t]ms dip & /rike4 ,:at is ! crop ( a b$8 ,:at are anticl9es & syncl9es8 #df4 ,:at is meant by an inv]sion ( /rata8 #dg4 ,h[ does contemporane\s erosion indicate a pause 9 ! deposition ( a s]ies ( /rata8 #dh4 ,:at is meant by uncon=mability8 ,h[ does uncon=mability prove a lapse ( "t betwe5 ! accumulation ( ! und]ly+ & ov]ly+ /rata8 #di4 ,:at is ov]lap8 #ej4 ,:at is a fault8 ,:at is hade8 ,h[ are ! /rata affect$ on ei!r side ( a fault8 ,:at is ! appe>ance call$ slick5sides8 ,"u :at circum/ances %\ld we t]m a fault a d[n?r[8 & :5 %\ld we t]m x an upca/8 ,h[ is ! approximate age ( a fault sometimes %ewn8 #ea4 ,:at are metamorphic rocks1 & :at is _! g5]al appe>ance8 ,9 :at di/ricts ( ! ,briti% ,isl&s are !y mo/ abundantly develop$8 ,:at are "s ( ! appe>ances reli$ ^u = di/+ui%+ metamorphic f igne\s granite8 #eb4 ,h[ d igne\s rocks occur8 ,def9e :at is meant by contemporane\s & subsequ5t or intrusive igne\s rocks4 ,h[ does a contemporane\s igne\s rock affect ! b$s ^u :i* x re/s8 ,:at is ! "* ( ! b$ ov]ly+ a contemporane\s rock8 ,:at is ! g5]al /ructure ( a contemporane\s igne\s rock8 ,:at is meant by vesicul> /ructure8 ,:at is ! g5]al texture ( a contemporane\s igne\s rock8 ,:at is ! nature ( ! jo9t+ 9 igne\s rocks8 ,:at is wacke8 #ec4 ,:at is ! nature ( ! b$s ( breccia1 conglom]ate1 a%1 & tuff1 ) :i* contemporane\s igne\s rocks are (t5 associat$8 ,:at is a neck ( volcanic agglom]ate8 ,h[ are ! /rata affect$ at _! junction ) a 'neck'8 #ed4 ,h[ d intrusive igne\s rocks occur8 ,h[ d intrusive %eets occur8 ,:at effect h !y produc$ ^u ! /rata above & bel[ !m8 ,:at is a dyke8 ,:at relation d !y occasionally be> to %eets ( igne\s rock8 ,:at is a neck ( intrusive igne\s rock1 & h[ h ! /rata surr\nd+ x be5 affect$8 #ee4 ,m5tion "s ( ! contra/s betwe5 intrusive & contemporane\s igne\s rocks4 ,:at alt]ation is produc$ ^u coal ) :i* an intrusive %eet has come 9 contact8 #ef4 ,:at are m9]al ve9s8 ,:at is ! nature ( ! qu>tz ve9s 9 granite8 ,h[ are ! m9]als usually arrang$ 9 ! great metallif]\s ve9s8 ,:at is a pipe-ve98 #eg4 ,:at are ! great geological ag5ts ( *ange8 #eh4 ,:at is meant by wea!r+8 ,h[ are rocks affect$ at ! surface 9 tropical c\ntries8 ,:at *emical effect has ! atmosph]e on calc>e\s rocks8 ,h[ is soil =m$8 ,h[ are s& dunes =m$8 ,m5tion "s effects ( ! transport+ p[] ( ! atmosph]e4 #ei4 ,m5tion "s ( ! *emical effects ( int]/itial wat]4 ,:at is ! orig9 ( trav]t9e or calc>e\s tufa8 #fj4 ,h[ h /alactites & /alagmites be5 =m$8 ,give "s in/ances ( ! solv5t p[] ( spr+s4 #fa4 ,h[ are caves 9 lime/one =m$8 ,describe "s ( ! appe>ances ( a c\ntry compos$ ( calc>e\s rocks4 ,describe briefly h[ a riv] erodes its *annel4 #fb4 ,describe ! geological action ( ra94 #fc4 ,:at d *emical analyses ( riv]-wat] prove8 ,give an example4 ,:at are pot-holes8 ,give an example ( ! erosive p[] ( runn+ wat]4 ,:at am\nt ( mud is c>ri$ 9 susp5sion by ! ,mississippi1 & dis*>g$ annually into ! sea8 ,:at e/imate has be5 =m$ ( ! total am\nt ( m9]al matt] annually transport$ by t riv]8 #fd4 ,:at is alluvium8 ,h[ is x =m$8 & m5tion "s examples ( its occurr5ce4 #fe4 ,h[ is s$im5t deposit$ by a riv] 9 a lake8 #ff4 ,:at is ! diff]5ce betwe5 lacu/r9e & fluvio-m>9e deposits8 ,:at is a delta8 #fg4 ,describe ! geological action ( fro/4 ,describe ! geological action ( riv]-ice4 #fh4 ,:at are glaci]s8 ,:at ?ickness d !y atta9 9 ! ,alps8 ,:at is _! rate ( motion8 ,:at are crevasses1 & h[ d !y orig9ate8 ,:at are sup]ficial mora9es8 ,:at are t]m9al mora9es8 ,:at *anges does a glaci] effect ^u its b$1 & h[ are ^! modifications produc$8 ,:at is ! "* ( a glacial riv]8 ,:at is ! orig9 ( iceb]gs8 ,h[ is ! g5]al abs5ce ( blocks & /ones 9 ,gre5l& iceb]gs to be expla9$8 ,:at is ! nature ( a subm>9e t]m9al mora9e8 ,:at is ! ice-foot8 ,:at is ! *ief ag5t 9 di/ribut+ erratic /ones & blocks ov] ! sea-bottom8 ,:at effect ^u ! sea-b$ mu/ /r&+ iceb]gs produce8 #fi4 ,:at are "s ( ! *emical comp\nds held 9 solution 9 sea-wat]8 ,:i* ( ^! g to =m ! %ells & skeletons ( m>9e animals8 #gj4 ,describe ! action ( break]s on a sea-coa/4 ,h[ does fro/ aid ! wa/+ action ( break]s8 ,:at effect has ! nature ( ! rocks 9 ! production ( inequalities 9 a coa/-l9e8 ,^u :at "p ( ! sea-bottom does ! mat]ial d]iv$ by ! action ( ! break]s *iefly accumulate8 ,:at effect h ! tides & ocean curr5ts 9 ! di/ribution ( s$im5t8 #ga4 ,:at is ! g5]al rule z reg>ds f9e-gra9$ & co>se-gra9$ deposits8 ,m5tion a p>tial exception to ?is rule4 ,:at effect h tidal curr5ts 9 %all[ seas8 #gb4 ,h[ are rocks dis9tegrat$ ?r\gh ! action ( plants8 ,:at is peat8 ,:at may be inf]r$ f ! occurr5ce ( %ell-m>l und]nea? peat8 ,:at does ! appe>ance ( roots & trunks ( trees1 & ( rema9s ( l& animals "u peat1 indicate8 #gc4 ,:at1 g5]ally1 is ! geological action ( animal life8 #gd4 ,:at is coral8 ,:at is a fr++ reef8 ,:at is ! g5]al "* ( a b>ri] reef8 ,give an example ( "o4 ,:at is an atoll8 ,:at is ! nature ( coral rock8 ,:at is ,mr ,d>w9's !ory ( ! =mation ( coral reefs8 #ge4 ,:at is ! nature ( ! ,atlantic ooze8 ,9 :at respects may x ev5tually come to resemble *alk & lime/one8 ,m5tion an in/ance ( ! abundant occurr5ce 9 ! sea ( animalcules ) silice\s cov]+s & skeletons4 ,:at is ! nature ( ! r$ clay f\nd at great dep?s 9 ! ,atlantic & ,s\!rn ,oceans8 #gf4 ,:at are "s ( ! notions held 9 reg>d to ! int]nal condition ( ! e>?8 ,at :at 7av]age7 rate does ! temp]ature ( ! e>?'s cru/ increase z we desc5d f ! surface8 #gg4 ,:at is ! nature ( ! movem5ts to :i* ! e>?'s cru/ is subject$8 #gh4 ,describe ! hypo!ses advanc$ to acc\nt = e>?quakes4 ,m5tion "s ( ! effects ( e>?quakes--#a/1 z reg>ds alt]ations ( level2 & #b;d1 z reg>ds modifications ( ! surface4 #gi4 ,m5tion a good example ( tranquil elevation & depression ( ! e>?'s cru/4 ,m5tion "s ( ! pro(s ( an elevatory movem5t4 ,give pro(s t %ew depression ( ! l&4 ,h[ may c]ta9 =m] *anges ( sea-level be acc\nt$ = )\t inf]r+ any movem5t ( ! l&8 #hj4 ,:at effect mu/ depression h ^u ! /rata =m+ ! e>?'s cru/8 ,:at is ! result ( a movem5t ( elevation8 ,:at is ! cause ( cleavage8 #ha4 ,:at is ! nature ( ! mat]ials ?r[n out dur+ volcanic eruptions8 ,:at is ! g5]al /ructure ( a volcanic cone8 ,h[ does molt5 rock make its escape f ! orifice ( eruption8 ,:at is ! mean+ ( ! t]ms lapillo1 puzzolana1 & c5]i8 #hb4 ,:at is lava8 ,describe ! g5]al appe>ance & mode ( progression ( a /ream ( lava4 ,:at effect is produc$ ^u fragm5ts ( rock caught up & inclos$ 9 lava2 & :at *anges are caus$ 9 ! pavem5t ^u :i* x cools8 ,h[ does a lava /ream ent]+ a lake or ! sea behave 9 reg>d to ! s$im5t ga!r+ !re98 ,to :at is ! basaltic /ructure due8 ,h[ are ! axes ( ! prisms 9 a column> igne\s rock arrang$8 ,"n "s ( ! v>ieties ( lava4 ,:at is ! orig9 ( ! vesicul> /ructure 9 igne\s rocks8 ,:at portions ( a b$ ( lava are mo/ frequ5tly scoriace\s8 ,9 :at k9ds ( lava is ! vesicul> /ructure mo/ abundantly met )8 ,h[ h ! vesicles become flatt5$8 ,9 :at mann] h !y be5 fill$ ) m9]al matt]8 ,:at is ! orig9 ( ! dykes ( mod]n volcanic di/ricts8 #hc4 ,h[ is metamorphism on ! l>ge scale suppos$ to h be5 induc$8 ,h[ may granite be at "o & ! same "t a metamorphic & igne\s rock8 #hd4 ,m5tion "s ( ! views held ) reg>d to ! orig9 ( m9]al ve9s4 #he4 ,:at is d5udation8 ,h[ d incl9$ /rata prove t ! /rata h be5 d5ud$8 ,h[ d faults af=d pro( ( d5udation8 ,:at h be5 ! g5]al effects produc$ by d5udation on ! face ( ! l&8 #hf4 ,:at "p h ! subt]ranean =ces act$ 9 ! =mation ( m\nta9s8 ,to :at geological action is ! pres5t aspect ( ^! m\nta9s due8 ,:at has det]m9$ ! direction ( riv] valleys8 ,h[ h ! valleys1 dells1 c4 be5 =m$8 ,:at effect h faults _h 9 det]m9+ ! direction ( riv] valleys8 ,:at is suppos$ to be ! orig9 ( ! deep rock-bas9s occupi$ by _m fre%-wat] lakes8 ,h[ is ! wa/e ( l& by d5udation comp5sat$8 #hg4 ,:at are fossils8 ,:at is meant by petrifaction8 ,9 :at k9d ( rocks d fossils occur mo/ abundantly1 & 9 ! be/ /ate ( pres]vation8 & :at reason c be giv5 = ?is8 #hh4 ,h[ d fossils af=d pro( ( v>i$ physical conditions8 ,give a reason = "s rocks be+ m b>r5 ( fossils ?an o!rs4 #hi4 ,/ate "s ( ! *>act]s :i* di/+ui% broadly ! old] fossilif]\s /rata f ^? simil> accumulations :i* are be+ =m$ 9 our own day4 #ij4 ,h[ may we id5tify =mations 9 sep>ate di/ricts8 ,h[ is ! int]rupt$ & p>tial di/ribution ( /rata to be acc\nt$ =8 #ia4 ,9 :at respect d ! fossils 9 y\ng] /rata diff] f ^? 9 old] /rata8 ,:at g5]al pro( c be adduc$ to %ew t species h become gradually ext9ct8 #ib4 ,give an in/ance h[ fossils prove *anges ( climate 9 ! pa/4 ,:at is suppos$ to be ! cause ( great cosmical *anges ( climate8 ,describe ,mr ,croll's !ory ( cosmical *anges ( climate4 #ic4 ,:at is ! te/ ( sup]position8 ,m5tion ano!r te/ ( ! relative age ( /rata4 #id4 ,"n ! f\r great divisions "u :i* ! fossilif]\s rocks are arrang$4 #ie4 ,"n ! ,prim>y or ,palaeozoic =mations4 ,:at are ! pr9cipal k9ds ( fossils f\nd 9 ! ,old ,r$ ,s&/one8 ,:i* =mation is ! *ief repository ( coal 9 ,brita98 #if4 ,9 :at o!r =mations d coals occur8 ,9 :i* =mation d ! olde/ kn[n mammals occur8 ,"n ! ,second>y =mations4 #ig4 ,"n ! ,t]ti>y =mations4 ,:at k9d ( climate *>act]is$ ! nor!rn hemisph]e at ! beg9n+ ( ,plei/oc5e times8 ,:at k9ds ( climate w\ld appe> f ! evid5ce to h *iefly prevail$ 9 ,prim>y1 ,second>y1 & ,t]ti>y ages8 ,h we any trace ( frigid conditions dur+ ^! ages8 ,:at is ! gr[+ op9ion ) reg>d to ! climatic conditions dur+ ! glacial p]iod ( ,plei/oc5e times8 ,,! ,,end4 ,ed9burgh3 ,pr9t$ by ,w4 ,r4 ,*amb]s4 99 99 99 99 99 99 99 ,transcrib]'s ,notes ,! only m9or correction t 0 not$ 9 conv]t+ ?is docum5t f a pr9t$ v]sion into an electronic v]sion 0 an unpair$ p>5!sis on ! fir/ l9e ( ! ,title ,page4 99 99 99 99 99 99 99