,univ]sity ( ,texas ,bullet9 ,no4 #ahba3 ,april #aj1 #aiah ,fossil ,ice ,cry/als ,an ,in/ance ( ! ,practical ,value ( ,pure ,sci5ce ,illu/ration3 univ]sity emblem ,bureau ( ,economic ,geology & ,te*nology ,division ( ,economic ,geology ,j4 ,a4 ,udd51 ,director ( ! ,bureau & ,head ( ! ,division ,publi%$ by ! ,univ]sity six times a mon? & ent]$ z second-class matt] at ! po/(fice at ,,au/91 ,,texas ,publications ( ! ,univ]sity ( ,texas ,publications ,committee3 ,f4 ,w4 ,,graff ,j4 ,m4 ,,bryant ,d4 ,b4 ,,ca/eel ,,fr$]ic ,,duncalf ,r4 ,h4 ,,griffi? ,j4 ,l4 ,,h5d]son ,i4 ,p4 ,,hildebr& ,e4 ,j4 ,,ma!ws ,! ,univ]sity publi%es bullet9s six times a mon?1 s numb]$ t ! fir/ two digits ( ! numb] %[ ! ye> ( issue2 ! la/ two ! position 9 ! ye>ly s]ies4 7,= example1 ,no4 #agja is ! fir/ bullet9 ( ! ye> #aiag47 ,^! comprise ! (ficial publications ( ! ,univ]sity1 publications on humani/ic & sci5tific subjects1 bullet9s prep>$ by ! ,dep>tm5t ( ,ext5sion & by ! ,bureau ( ,municipal ,rese>* & ,ref]5ce1 & o!r bullet9s ( g5]al educational int]e/4 ,) ! exception ( special numb]s1 any bullet9 w be s5t to a citiz5 ( ,texas free on reque/4 ,all communications ab\t ,univ]sity publications %\ld be address$ to ! ,*airman ( ! ,publications ,committee1 ,univ]sity ( ,texas1 ,au/94 ,univ]sity ( ,texas ,bullet9 ,no4 #ahba3 ,april #aj1 #aiah ,fossil ,ice ,cry/als ,an ,in/ance ( ! ,practical ,value ( ,pure ,sci5ce ,illu/ration3 univ]sity emblem ,bureau ( ,economic ,geology & ,te*nology ,division ( ,economic ,geology ,j4 ,a4 ,udd51 ,director ( ! ,bureau & ,head ( ! ,division ,publi%$ by ! ,univ]sity six times a mon? & ent]$ z second-class matt] at ! po/(fice at ,,au/91 ,,texas ,! b5efits ( education & ( useful k1 g5]ally diffus$ ?r\gh a community1 are ess5tial to ! pres]vation ( a free gov]nm5t4 ,sam ,h\/on ,cultivat$ m9d is ! gu>dian g5ius ( democracy4444 ,x is ! only dictator t freem5 ackn[l$ge & ! only security t freem5 desire4 ,mirabeau ,b4 ,lam> ,,fossil ,,ice ,,cry/als ,,by ,j4 ,a4 ,,udd5 ,,an ,,in/ance ,,( ,,! ,,practical ,,value ,,( ,,pure ,,sci5ce ,! practical value ( ! s]vice ( ! geological pr(ession is1 ) e ye>1 be+ m & m appreciat$1 especially among p :o are develop+ ! m9]al res\rces ( our c\ntry4 ,nev]!less1 we /ill he> m5 :o speak ( geologi/s z !ori/s t r5d] our pr(itable indu/ries b little assi/ance4 ,x is true t mu* ( ! "w t geologi/s d has b a remote be>+ on practical que/ions4 ,! fact is t 9 geology1 z 9 o!r sci5ces1 "o c nev] "k :5 a purely sci5tific obs]vation may turn out to h a practical application4 ,paleontologi/s :o /udy ! m9ute/ details ( fossils h be5 held up z impractical p1 ev5 ?\gh _! sci5ce has m ?an once prov$ to be ( ! greate/ practical importance = ! f9d+ ( valuable natural deposits4 ,c]ta9ly ^? :o h be5 mo/ prom95t 9 ! promotion ( paleontology z a sci5ce h seldom1 if ev]1 _h any economic motive 9 ! pursuit ( _! "w4 ,i ?9k ! same is true ( our lead+ petrograph]s4 ,i believe t ! m5 :o h advanc$ ! sci5ce ( geology mo/1 h seldom contribut$ mu* to ! practical application ( ! pr9ciples !y h discov]$4 ,mu* sci5tific "w naturally appe>s unpr(itable or useless to ! un9itiat$4 ,i %all "h relate a case t sugge/s h[ entirely wrong x may be to reg>d z ( no economic value any geologic fact1 h[ev] insignificant x may appe>4 ,9 ! summ] ( #ahij ,i took occasion to make a trip to ! ,black ,hills 9 ,s\? ,dakota 9 ord] to pr(it1 z ,i c\ld1 by a few weeks' tramp+ 9 ?is int]e/+ region4 ,go+ "o day 9 a s\?we/ direction f ,m9nekahta1 to look = fossil cycads1 ,i /umbl$ on a block ( s&/one ) a r smoo? surface on :i* 7 "s peculi> m>k+s1 su* z ,i _h nev] se5 figur$ or describ$4 ,! rock 0 evid5tly a block f ! ,dakota s&/one4 ,its smoo? upp] surface1 :i* repres5t$ a b$d+ plane1 0 cov]$ ) a ?9 coat+ ( silt or f9e clay :i* adh]$ to ! block4 ,! m>k+s 7 9 ?is clay4 ,!y 7 /raight1 %all[ grooves f "o-half to two in*es 9 l5g?1 & f "o-sixte5? to "o-eigh? in* 9 wid?4 ,!y 7 jo9$ into patt]ns 9 :i* "s sprang out f ! sides ( o!rs & aga9 !mselves s5t out o!r bran*es4 ,"s cross$ ea* o!r4 ,i notic$ t !re 0 a q uni=m angle ( div]g5ce 9 ^! bran*es1 & ,i 0 able to make out t ?is usual angle 0 ab\t sixty degrees4 ,i also not$ t ! grooves n>r[$ to %>p po9ts4 ,someh[1 imm$iately ,i conclud$ t ! cracks 7 ! result ( ice cry/als1 & ,i at once saw ! propriety ( froz5 wat] hav+ exi/$ 9 an age dur+ :i* decidu\s trees began to appe>4 ,?is 0 !ory4 ,we h s9ce t "t le>n$ to "k t cold climates f> ant$ate ! com+ ( ! dicotyl$ons4 ,z ,i _h no suitable photographic equipm5t1 ,i took pa9s to make accurate draw+s ( a "p ( ! patt]n z x appe>$ on ! rock4 ,my orig9al draw+ is %[n 9 ,plate ,i4 ,a brief description ( ^! m>k+s 0 lat] furni%$ 9 ! ,sci5tific ,am]ican1 ( ,febru>y #ai1 #ahie4 ,x took me "s ye>s to f9d any simil> m>k+s aga94 ,9 ! e>ly spr+ ( #aijc ,i _h occasion to make a visit to ,mexico1 :5 ,i sp5t a half day 9 ,oj9aga1 :i* is a little village s\? ( ,presidio1 9 ,texas1 on ! ,mexican side ( ! riv]4 ,"s sidewalks 9 ?is little village are built ( flags ( lime/one belong+ to ! ,eagle ,=d =mation4 ,to my great delight ,i f\nd "s ( ^! slabs hav+ precisely ! same k9d ( m>k+s t ,i _h not$ on ! s&/one 9 ,dakota4 ,naturally ,i atta*$ "s importance to ! fact t ! ,eagle ,=d corresponds q closely 9 age to t ( ! ,dakota s&/one4 ,bo? 7 made at ab\t ! beg9n+ ( ! upp] ,cretace\s age4 ,i notic$ "h a consid]able v>iation 9 ! clos5ess ( ! patt]ns ( ! m>k+s4 ,occasionally !y 7 f\nd z sep>ate s+le l9es1 sev]al in*es remov$ f ea* o!r2 & on o!r rocks !y w\ld be f\nd cross+ 9 close networks4 ,9 ! summ] ( #aijd ,i aga9 f\nd my ice m>k+s on a lay] ( ar5ace\s lime/one 9 ! same =mation 9 ! ,big ,b5d c\ntry 9 ,texas4 ,?is "t ,i collect$ "s specim5s :i* 7 subsequ5tly photograph$4 ,"o ( ^! photographs is %[n 9 ,plate ,,ii4 ,aga9 9 #aijf ,i notic$ ! same m>k+s on "s ?9 s&y flags :i* occur 9 ! ,del ,rio clay ne> ! city ( ,del ,rio4 ,9 ?is case ! ne$le-l cry/als 7 some:at m sl5d] ?an ^? previ\sly se51 & "s 7 slightly curv$ & some:at m elongat$4 ,^! ( c\rse int]e/$ me z %[+ ! occurr5ce ( freez+ temp]atures no d\bt at a some:at e>li] "t ?an t p]ta9+ to my previ\s obs]vations4 ,dur+ all ^! ye>s my resid5ce 0 9 ,ill9ois1 & ,i 0 naturally wat*+ = simil> m>k+s 9 rec5t mud1 result+ f late & e>ly fro/s4 ,i f\nd !m 9 ! fall ( #aiji4 ,at ?is "t "s excavations 7 be+ made 9 ! loess 9 ,rock ,isl&1 :5 "s ra9s fell 9 ! late fall4 ,^! ra9s evid5tly happ5$ to give ! mud ! am\nt ( moi/ure necess>y = su* cry/als to develop1 z ! gr\nd froze4 ,! ra9s _h wa%$ ! loess ext5sively1 & ,i f\nd a numb] ( places :]e x lay r$i/ribut$1 ) a fairly smoo? surface4 ,x 0 evid5t t ! moi/ure cont5t ( ! gr\nd1 toge!r ) ! temp]ature conditions1 det]m9$ ! size & ! clos5ess ( ! froz5 patt]ns4 ,9 places ! cry/als 7 long & sl5d]1 9 o!rs !y 7 %ort & /\t4 ,at "s po9ts !y 7 /raight & 9 o!rs slightly curv$4 ,"h & !re ! patt]ns 7 close en\gh to resemble ! f9e l9es :i* we sometimes notice 9 ! ho>fro/ on w9d[panes4 ,9 o!r places ! cry/als occurr$ 9 radiat+ gr\ps1 & else:]e !y w\ld =m scatt]$ sep>ate units4 ,= pres]v+ a record ( :at ,i saw1 ,i p\r$ pla/] ov] sev]al patt]ns & _h ^! ca/s photograph$1 z appe>s 9 ,plates ,,viii1 ,,ix1 ,x4 ,plac+ ^! side by side ) ! photographs ( ! patt]ns ,i h photograph$ f ! ,eagle ,=d1 x appe>s to me t no d\bt c be left z to ! orig9 ( ! m>k+s f\nd 9 ! fossil /ate4 ,rec5tly ,i h f\nd t ^! ice cry/al m>ks are q common at "o horizon 9 ! ,eagle ,=d b$s ( ,brew/] ,c\nty1 9 ,texas4 ,!re is also a lay] 9 :i* !y c be usually se5 9 ! vic9ity ( ,au/91 ,texas4 ,?is lies ab\t tw5ty-five feet bel[ ! ,au/9 ,*alk1 ne> ,au/94 ,a l lay] occurs ab\t #ajj feet bel[ ! ,au/9 ,*alk 9 ! ,big ,b5d c\ntry4 ,"h ,i h f\nd ! m>k+s 9 localities ?irty miles ap>t4 ,!y occur at ! nor? po9t ( ,m>iscal ,m\nta9 & 9 a numb] ( places ne> ! ,fossil ,knobs & on ! ,*isos ,m9+ ,company prop]ty at ,t]l+ua4 ,unpr(itable z obs]vations on su* a simple matt] z ?is may seem1 ,i f9d t o!r geologi/s h giv5 x "s att5tion4 ,q rec5tly1 ,dr4 ,john ,m4 ,cl>ke,a has figur$ slabs %[+ :at has be5 describ$ z ,fucoides graphica1 by ,hall4 ,! m>k+s figur$ by ,pr(essor ,cl>ke are und\bt$ly ( ! same k9d z ^? ,i h f\nd 9 ! ,eagle ,=d4 ,!y occur 9 ! ,upp] ,devonian 9 ,new ,york4 ,i also f9d t ! =mation ( ice cry/als 9 wet mud has be5 obs]v$ 9 ! clays ab\t ,bo/on by ,m>but & ,woodwor?4,b ,o!r obs]vations ( simil> rec5t m>k+s are said to h be5 made by "s ,engli% geologi/s4 ,to practical p x may inde$ appe> t no m unpr(itable or m idle curiosity c\ld be indulg$ 91 ?an mak+ obs]vations on :at k9d ( cry/als are =m$ :5 wat] freezes 9 mud4 ,i mu/ confess t my own fir/ obs]vations _h no motive :atev]1 except = ! desire to "k some?+ new2 & ,i nev] expect$ t any?+ ,i c\ld le>n ab\t ^! fossil m>ks w\ld ev] turn out to h any practical application1 at lea/ n 9 my own "w4 ,b x has turn$ out diff]5tly4 ,= "s "t1 ,i h be5 call$ ^u occasionally to advise ) reg>d to ! f9d+ ( ! ore 9 "o ( our quicksilv] m9es 9 ,we/ ,texas4 ,x is n[ a well e/abli%$ fact t ! di/ribution ( ! ore 9 ?is m9e1 & ,i believe 9 ! entire ,t]l+ua di/rict1 be>s a def9ite relation to geological horizons4 ,successful m9+ requires se>* 9 ^! horizons4 ,! c9nab>1 z x appe>s1 has accumulat$ 9 greate/ quantity "u imp]vi\s rocks su* z %ales & m>ls along planes t sep>ate ^! f und]ly+ rocks ( m op5 texture1 mo/ly lime/ones4 ,! ore has cle>ly come f bel[ & has ris5 ?r\gh fissure planes1 :i* 9 "s cases sep>ate l>ge blocks ( ! ,cretace\s =mations4 ,! be/ ore has be5 f\nd "u ! basal "p ( ! ,boquillas flags1 & "u ! ,del ,rio clay 9 ! upp] "p ( ! ,georget[n lime/one4 ,! work+s mu/ be s arrang$ 9 ! m9e t ^! horizons c be ent]$ on bo? sides ( a fault fissure4 ,! problem ( locat+ ! dep? ( ! desirable horizons 9 ! m9e 9 "q w\ld be easy en\gh1 if x 7 n = ! fact t ! outcropp+ rocks consi/ ( a s]ies ( s$im5ts ) few *>act]i/ic fossils4 ,mo/ ( ! fossils :i* occur ext5d ?r\gh a range ( sev]al hundr$ feet & ! b$s !mselves are q uni=m 9 "*1 consi/+ ( alt]nat+ ?9 lay]s ( impure lime/ones & m>ls4 ,an attempt 0 made to correlate ! outcropp+ b$s by close exam9ation ( ! lay]s expos$1 b ! result 0 n v satisfactory4 ,a close scrut9y made ( ea* lay] on ! section result$1 h[ev]1 9 ! f9d+ ( two features t enabl$ me to measure ! ?r[ ( ! fault "u inve/igation4 ,int]b$d$ 9 ! ,boquillas flags !re are "s ?9 lay]s ( b5tonite1 :i* are q p]si/5t & c be foll[$ = sev]al miles4 ,by comp>+ ! di/ances betwe5 ^! lay]s & by tak+ note ( _! individual ?ickness1 x 0 possible to make a correlation t seem$ to be correct4 ,b ! pro( s\ght fell j %ort ( be+ c]ta94 ,9 cases ( ?is k9d "o always looks = corroborat+ facts to *eck "o's conclusions4 ,i f\nd ?is *eck 9 ! discov]y ( ! lay] :i* c>ries ice cry/al m>k+s 9 ^! b$s4 ,! lay] _h a def9ite relation to ! seams ( b5tonite1 &1 ) ?is additional evid5ce1 ,i 0 confid5t !re 0 no possible *ance ( a mi/ake4 ,x enabl$ me to locate n only ! "r horizon b also a horizon 9 ! und]ly+ heavy ,coman*ean lime/one1 :i* is wat]-be>+1 & :i* mu/ be avoid$ to prev5t s]i\s injury to ! und]gr\nd op]ations4 ,i ne$ n add t ! in=mation obta9$ 0 ( real practical value 9 ?is case4 ,,plate ,i ,plate ,i4 ,=ms ( fro/ cracks se5 on ! expos$ flat b$d+ plane ( a block ( ,dakota s&/one 9 a rav9e a few miles s\?we/ ( ,m9nekahta1 ,s\? ,dakota4 ,z sket*$ 9 ! field4 ,natural size4 ,illu/ration3 ,,plate ,i ,,plate ,,ii ,plate ,,ii4 ,photographs ( fossil impr9ts ( ice cry/als on flags ( ! ,eagle ,=d4 ,! upp] rock %[n 9 ! ,plate is f ! s\? side ( ,cue/a ,blanca 9 ,brew/] ,c\nty1 ,texas1 & %[s ca/s ( cry/als :i* repres5t fill+s ( s&y mud project+ slightly d[n into an und]ly+ b$ ( m argillace\s mat]ial4 ,! l[] "p ( ! figure %[s a simil>ly m>k$ flag f ! same =mation at a po9t ab\t five miles nor? ( ! old ,boquillas po/(fice ne> ,tornillo ,creek1 ea/ ( ! ,*isos ,m\nta9s1 9 ,texas4 ,"h are se5 ! orig9al grooves made by ! ice on a lay] ( muddy mat]ial lat] buri$4 ,slightly r$uc$4 ,illu/ration3 ,,plate ,,ii ,,plate ,,iii ,plate ,,iii4 ,photograph ( fossil ca/s ( a close tangle ( ice cry/als se5 9 a /ony calc>e\s lay] 9 ! ,eagle ,=d %ale 9 ,walnut ,creek1 ab\t eight miles nor? ( ,au/91 ,texas4 ,?is tangle is clos] ?an any ( ! rec5t ice cry/al m>ks figur$ "h1 b equally closely gr[n cry/als h be5 se5 by ! writ] on froz5 mud 9 ,ill9ois4 ,natural size4 ,comp>e ) ,plate ,,viii4 ,illu/ration3 ,,plate ,,iii ,,plate ,,iv ,plate ,,iv4 ,photograph ( fossil ca/s ( ice cry/als se5 on "s /ony flags 9 ! upp] "p ( ! ,eagle ,=d at ,fossil ,knobs1 ab\t two miles nor?we/ ( ! ,*isos ,m9e 9 ,brew/] ,c\nty1 ,texas4 ,^! may be *>act]iz$ z relatively %ort & scatt]$4 ,?is %[s ridges project+ into ! grooves =m$ by ice cry/als on ! surface ( a muddy lay] orig9ally und]ly+ ! lay] photograph$4 ,slightly r$uc$4 ,illu/ration3 ,,plate ,,iv ,,plate ,v ,plate ,v4 ,photograph ( fossil ca/s ( ice cry/als se5 on ! "u side ( flaggy lay] ( calc>e\s s&y rock 9 ! upp] "p ( ! ,eagle ,=d at ,fossil ,knobs1 ab\t two miles nor?we/ f ! ,*isos ,m9+ ,company's prop]ty1 ,brew/] ,c\nty1 ,texas4 ,x w be se5 t "s ( ! cry/als are g5tly curv$4 ,simil> curv+ cry/als are also se5 9 ! figures %[+ rec5t gr[?s at ,rock ,isl&1 ,ill9ois4 ,comp>e ) ,plate ,,ix4 ,slightly r$uc$4 ,illu/ration3 ,,plate ,v ,,plate ,,vi ,plate ,,vi4 ,photograph ( a ?9 flag ( s&y lime/one f ! ,eagle ,=d at ,fossil ,knobs 9 ,brew/] ,c\nty1 %[+ molds left by ice cry/als4 ,illu/ration3 ,,plate ,,vi ,,plate ,,vii ,plate ,,vii4 ,photographs ( ?ree fragm5ts ( flags %[+ ca/s ( ice cry/als on ! "u side4 ,all obs]vations made on cry/als ( ?is k9d indicate local diff]5ces 9 ! =ms ( ice cry/als presumably due to diff]5ces 9 ! rate ( freez+1 9 ! texture ( ! mud & probably 9 v>iations 9 wat] cont5t ( ! mud4 ,"s cry/als 9 ! locality f :i* ^! specim5s came1 %[ p9nate second>y gr[?s4 ,specim5s %[n "h are f ne> ! upp] "p ( ! ,eagle ,=d at a po9t ab\t two miles nor? f ! ,*isos ,m9+ ,company's prop]ty4 ,brew/] ,c\nty1 ,texas4 ,slightly r$uc$4 ,illu/ration3 ,,plate ,,vii ,,plate ,,viii ,plate ,,viii4 ,photograph ( a ca/ made by p\r+ pla/] ov] a surface ( mud 9 :i* ice cry/als _h rec5tly =m$1 9 ,rock ,isl&1 ,ill9ois1 aft] ! ice 9 ! cry/als _h be5 remov$ by sl[ natural sublimation into ! atmosph]e1 leav+ op5 cracks 9 ! mud4 ,! comb-l ridges on ! pla/] ca/ h ! =m ( ! ice cry/als4 ,comp>e ) ,plate ,,iii4 ,illu/ration3 ,,plate ,,viii ,,plate ,,ix ,plate ,,ix4 ,photograph ( a ca/ made by p\r+ pla/] ov] a surface ( mud 9 :i* ice cry/als _h =m$1 9 ,rock ,isl&1 ,ill9ois1 soon aft] ! ice 9 ! cry/als _h be5 remov$ by sl[ natural sublimation into ! atmosph]e1 leav+ op5 cracks 9 ! mud4 ,9 ! locality :]e ?is ca/ 0 made1 ! cry/als 7 relatively sl5d]1 di/ant1 & "s g5tly curv$1 l ^? se5 9 ,plate ,v4 ,slightly r$uc$4 ,illu/ration3 ,,plate ,,ix ,,plate ,x ,plate ,x4 ,photograph ( a ca/ made by p\r+ pla/] ov] a surface ( mud 9 :i* ice cry/als _h rec5tly =m$1 9 ,rock ,isl&1 ,ill41 & :]e !y _h lat] be5 remov$ by natural sublimations into ! atmosph]e1 leav+ op5 cracks 9 ! mud4 ,x w be se5 t ! cry/al gr[? 9 ?is case involves an x-l or radiat+ patt]n =m$ ( relatively v sl5d] =ms t almo/ ev]y:]e are v g5tly curv$ some:at rem9d+ ( ! sl5d] ?read-l cry/als sometimes se5 9 fro/ on w9d[s4 ,i h n yet se5 any simil> fossil cry/al gr[?s z sl5d] z ^!4 ,slightly r$uc$4 ,illu/ration3 ,,plate ,x ,,footnotes3 ,a ,/r& & und]t[ m>k+s1 etc41 ,new ,york ,/ate ,museum1 ,bullet9 ,no4 #aif1 ,april #a1 #aiag1 pp4 #aii-baj2 pl4 #bj-bc4 ,b ,brick clays ( ,rhode ,isl&1 ,massa*usetts2 ,m>but & ,woodwor?1 ,u4,s4 ,geol4 ,survey1 #ag? ,ann4 ,rep41 ,pt4 #a1 p4 #iib4 ,transcrib]'s ,notes3 ,passages 9 italics are indicat$ by und]score4 ,pr9t]'s inconsi/5cies 9 spell+ & punctuation h be5 reta9$4