SYST: rae tii Serpe: “wet Sybian aaaree a» THE FIELD MUSEUM LIBRARY 5711 00014 22 uh ANNUAL REPORT OF m™ THE UNITED STATES “GEOLOGICAL AND GEOGRAPHICAL SURVEY gs ee ee OF THE TERRITORIES, | ue | EMBRACING COLORADO, BEING A REPORT OF PROGRESS OF - THE EXPLORATION FOR THE YEAR 1873, BY BV 2 et Ay eID EN, UNITED STATES GEOLOGIST. a MB in 8415 Pees neers /EENDUCEED UNDER THE AUTHORITY OF THE SECRETARY OF THE INTERIOR, é WASHINGTON: GOVERNMENT PRINTING OFFIOE. 1874. ila he cae te CONTENTS. WEG PHeTALOMiD eC WECROLany seamiae nae comin cect sce eeie net. sae Sete sole woes Seles ests McR PART I.—GEOLOGY,.-MINERALOGY, AND MINING INDUSTRY. EPOLD Ole ba Vas Ay DEN U0. Se0lOpIStecenc = s/e a= wlalsiare nleinia.e General structural features of the mountain-border region...--..-------- IV CONTENTS. Report of Arch. R. Marvine—Continued. Chapter III. The metamorphic crystalline rocks of the mountains ......--. The stratigraphy of the east slope of the Front range ...--.--..--------- Chaptensiyaatiken ind dies arkweee ee teme eis ys ete eee etal tee eps The Cretaceous formation of the Middle Park........-..--.---.---.----- IDOE IKONS eGbo boos doo se Goomaoboelnseerossseobereocs cooscosoccor Dheliienitictormationyor the parker. ..2s= 05-20-24 a sae ee eee Dakesbedsior the Middle Parkas: 2.00. 2-.c2cer uses (Gibyor ea a eee a es oa SEAS Ser te See ae SE ee Cerio Ge ometcice Rees Mans yelloyy OLE wae Whooar Cmpitl S55 555 sobace soceau osdoanensmss0 seecce soc UU) J Mayas NSN) Cae S eee BG BeO ear os UMP SCU mam aMAb saa sdicascsos The region in the vicinity of the Hot Springs . Seat Sones Section of Cretaceous No. 1, near junction of Hot Spring os and Grand Lake roads, entrance of Middle Park |... seecen0 ac le ee Section of Cretaceous No. 1 at the mouth of the Frazier Canon. -.....---. The nonconformity at the Hot Springs, Middle Park........------:---..-- Whillitams River Vialleye ans csiy-oee cc\ariseteciesicers sierra beer ersretere Pera con! ihe morihernwinonithiclatedesseaeiee teases a eee eae eee eee eee Lower Troublesome Walley aij2 ss Seth tye o's cise dinie oe ene see ies sists Oe Vallevonthemuower Grands). .2-cfs0ic-.el 5+ cess oe os eee eee Mhervalleyiofithey Muddy ja. cesc ses cee = esse nice spaienie a iete see eer ihe walley of the bine) Biyerasan 2 ye cs see cue ese Seen alee The Parkirange and Blue River Mountains 2. . <4-2 2-22-22 2-22 esse see Gihe bined iver or Mount Rowell icroupeessese > ese a so eeeeee ee The southern end of the William’s Rivér range ...-...-...---.-----.---- Report of A. C. PEALE, M. D., Geologist of the South Park division .......-.--- Chapter I. From Denver to Colorado Springs—Front range—Bergen ene tay dentParke eos iat cia treet yaisiecaaje ereeicie arched tse Se Chapter wl South sPark—— Park ranges. --)-ss5 sees e eee eee peeved Chapter III. Arkansas Valley—Hagle River—Sawatch range...-.....---.-- Chapter IV. Gunnison River—H1lk Mountains—Roaring Fork... jai.puaman No —Cataloouelot, mineralsias2) 2 = s)ss 2c) ee See sone eo eee ee No. 2.—Catalogue of rocks. Be eye nie cece 5 Eiht Report of. F. M. ENDLICH, S.N. D.,[ geologist ‘of the San Luis fete. A Ss Se Chapter I. Preliminary report upon the mining-districts of Colorado...-...- Hormationjorvemsand odes 2255 .---e- ee oe a a eee ee eee eee Search for lodes_:-.-- 2... ANG shay ED Mines noted by the South Park division of the United States geological SUBVEVA ETO VAs eal ci 8e50 o1s 2) 20 iS auc ya geel tye Me Dra eee Marnyalli@reeke sie seis) bin aise adi Maes Soins a Se Ee eee Silence) sy Mommbaiine 222 eels io yan peer ek mene ere ee Wairye ays; COlOTACO 22 uses isicigh'«\Si1e spereecmsi ae ov See Sie SLs ee TO NO TOY ei ee ee oo ais sos Sek one ge Meld sare) Uist ap eI I RR AT can sas) Walleye se oni Sma St sfsim ces ste leilsgete AGS Ske aL ted eae a Hille Mountain: district sit ce scm eens ee Boe ceese ae Chapter II. Report upon the geology of the San Luis district [section A.]-- Chapter III. Geology of section B, San Luis division..............---.-.-. Chapter IV. Geology of section C; Sanvluisidivisionsaes—-- eee eee eee GOnElUSION aca woes aleea cat Decrees 2). ae are hae. )si- ci Appendix. Mineralogical notes and a catalogue of the minerals of Colorado SROREMCODY Cees hele smitaws in Sle ae else yoneyerereyais sists aiale sos Ae oe cea Mineralopicallen Obe8 assciisjaue Se ogee ese scram ame Sey ae ee PART IL.—SPECIAL REPORTS ON PALEOYTOLOGY. The Lignitic formation and its fossil flora, by Leo Lesquereux.............----- Tntroductiont 000.2 2 sCU UNG L WR Rk ss ue § 2, Distribution of the fossil Trae in the different groups of the Tertiary... List of the species of the first RUDI De Sn o5 ne seieeriasseenbes eabee6 66S cue = - Remarks on the species of the first group..--...----..---2.-..2e20+----s Mishor whespecies) of thesseconds exroup reassess cose lee elena Remarks on the species of the second group........-..----...-2-.-...--- ishionwheispeciesion ohne hindsoroupee seen er eae eee eee ee ee Remarks on the species of the third group List of the species of the fourth group CONTENTS. The Liguitie formation—Continued. Remarks on the species of the fourth group...--......----------....---- SK escriptionsonispecles acces, cine ce lree ne swrsiertsienlcta mmetaite ae sceels alee SPEcles Ol une ntinsheenOuUp =e eee tee acy see eee eee eee aioe Species Of uuerseCOndkeroOup seer secrete see tie ese ee ree eieae eee eoe Speciesiotesheibhind: /oroupeee cas teiceeceaacieeeeiee Seen e mee een ene § 4. Climate of the American Tertiary as represented in its flora.-......... Report on the vertebrate paleontology of Colorado. By Edward D. Cope, A.M. Chapter TvlntrodmehiOme se ecco tte tecrcrere cicirers eee Onion levee ele ere ee Chapiern Ueihe Cretaceous periodme see aeerereeaiae ee eee oe aaa ee Section I. On the mutual relations of the Cretaceous and Tertiary forma- DLONSIORNUMES WSSU Ue oN, scp eee re yeis SEEN SERN gals Uava Seman AND Arar nStT RUS ER OTI Section II. The Vertebrata of the Fort Union Cretaceous of Colorado.... Appendix. Descriptions of new mollusks from Cretaceous beds of Colorado, Diyas COMTACUE Rey ee fe ere eect eey are tats parents ge NIU a LE ee ELE Chapter III. The Eocene period.......... SHV DE AER EIN See P eR SDA eae Chapter Wey lieyMiocensiiperliocden ys ss ses ee ee ee eee cate a earls Chapters View bemoupmnonkie noel eerc cer secre eres eee eee cae sete oe tee EX) DY NSN TNE bse rec RPE cae eT oy 3. RS eS ETE HO 5 MME, oe Heras Gale PART III.—ZOOLOGY. 1, Report of Lieut. W. L. Carpenter on the collections made by him in 1873, while connected with the United States geological survey..-.-.---.---- 2. Destruction of Pine-timber-in the Rocky Mountains. By Lieut. W. L. Car- “POVS TUTE AN DIGS: 75 EI See 2 8 aR ne aE AN UY CN 3. Report on the Alpine Insect-fauna of Colorado. By Lieut. W. L. Carpenter, [le GERRI Ba 5 cr ees ath imeem 4 ela mi NE 106 aU La ao NA GA ER 4, List of species of Butterflies collected by Lieut. W. L. Carpenter, U.S. A., for the United States geological survey of Colorado, 1873. By W. H. Weawand seem aos ai sae cheer aese ee tees oee ee coum un Gk ue edema cea 5. On the gecgraphical distribution of the Moths of Colorado. [Figs. 1-15.] By A MO ACkATO LPs Misi ines aomt mas ceases eke uice cae see esee sae emaeeiee 6. Report on the Diptera collected by Lieut. W. L. Carpenter in Colorado during the summer of 1873. By C. R. Osten Sacken ....-............--------- 7. Notice on the Galls collected by Lieut. W. L. Carpenter. By C.R. Osten SSE CET a SIAR en TAL SNS Ae A hy ie Oe pe Se ea 8. List of species of Coleoptera collected by Lieut. W. L. Carpenter, U.S. A., ier the United States geological survey of Colorado, 1873. By Henry NER ei SE RE eects hae ee a RS A i aR a ORCA Fe aN A it) 9. Report on the Pseudo-Neuroptera and Neuroptera collected by Lieut. W. L. Carpenter in 1873 in Colorado. By Dr. H. A. Hagen...--..----.....---. 10. Report on the Myriopods collected by Lieut. W. L. Carpenter, in 1873, in Colo- sSEENA UY bagd Bade Nid 2 117 CO es Uhl B ean cr aT nt SNL a AL 11. Report on the Amphipod Crustaceans. By S.J. Smith ..................-.. 12. Description of a Lernzean Crustacean (Achtheres Carpenteri) obtained by Lieut. W.L. Carpenter, in 1873, in Colorado.. By A.S. Packard, jr.,M.D..-.... 13. Synopsis of the fresh-water Phyllopod Crustacea of North America. By A.S. Packard, jr., M. D..-.--. 50 GADSUS GOUSUD DO OS ED ODE Sos one DoS BeeEBereSaad se 14. List of leeches collected by Hayden’s expedition, 1873. By A. E. Verrill.... 15. List of terrestrial mollusks collected by Lieut. W. L. Carpenter, U. S. A., for the United States geological survey of Colorado, 1873. By William G. JST she soe - Bb85S ca OONS DSOS GUdOUD DO SUOUIb BS eae Epo eea eee eae mee au eBe PART IV.—GEOGRAPHY AND TOPOGRAPHY. Sketch of the methods of survey in the geographical department. By James T. SAMNETAPCONTAPREL Aue e anes ean aa ss oA SoReal oul DMN Omit Le The elevation of certain datum-points on the great lakes and rivers and in the Rocky Mountains. By James T. Gardner, geographer -..--......-..----- LASTRUN rene IL eg ber 88a NEP AE 8 0A BN Se Discussion of evidence of the altitudes of various points in the United States AHO AM ANE was aes a eect bk Mee yeaa ois ad oN We os he mheclevation af halke Ontario. .4099 fas chess ss cease elie. Soke Elevation of Buffalo, Cleveland directrix, and mean surface of Lake Erie From mean tide New York Bay to the Chicago directrix .........--.-.-. Elevation of Chicago directrix by G. T. R. W. of Canada and M.C.RR.. Movanon of Memplis, Denn: 22525222527 see doe sos nce ca osae daccsesceees PECULIAR IO OCA GOR Fae ot oa tok rer lore Saisiatneoad Aabdewedee Lek Results by M. & O. R. R. preliminary, compared with adopted levels. .... Elevation of Cincinnati city base, which is standard low water in Ohio Pelivenso2 50rfeeb: below THs Wh W832: 20 ocr b cer oooseseasoae eorcdseeode. 612 613 623 623 1 a CONTENTS. Discussion of evidence of the altitudes of various points in the United States and Canada—Continued. Rlevationyon in lianapolisa ss ssec sess sees cece a le Ces eee levationorthe sang Wouis dinectrixe-=--a-sssse sees tee eae Bileyatroniot Om aha eases a3) foe a caters Sens oteveele o)-tedee eee ets a eee see Hlevahlony ots lanrsasy Cithyiaeec ks acts one cate sae ele ie aie eee eee Blevationiot: Denvers Colomisssessie-c2 obese) ose saan te ae eee Elevation of Cheyenne ..--.....--:.---- Sep sebs socccs Sad esbeasose sce5s> HlevationvoiGoldentidinectrixece. >. -s ceo o eno se eae eee eee eee Jdilkexreiokonn Ot Ckerdlenny, Wig Ns aoe seems oadiee Soosee ds acusbebossedede Pr seheys Elevation of Colorado SPINS) a. ahs Se ots eae ee ae Rievabionvotubike siPealke es 0). Voy eck el, Sia ee ee ee HilevanonomMvMount imcolnvand shan Playas see eles) eee Hlevainionvotspoimtsyonighe: Ohio) iver. eeee 6-1 eens e eee eee eee Mlevationioh Cairo ewok aed Le el ele eee a EKlevation of points determined in this investigation....-....----..---.- Topographical report of Middle Park division, 1873. By 8S. B. Ladd, M. E_-... Geographical report of Henry Gannett) Me Bie. 52) fl a ee a (Cremeraul Penis | osece goene aeesen esoseadaseda seeasoaseocs accsso< see Principal passes in the high mountains ---.......-.-----2--2---+.-2---e- Meanstofscormmmunmicavions. Vac 2042 es ee eae ei) ores ee ee nee nine palawacon-roadsiandsthallseeoeeere ees eee see ee eee eee Bopanicalinotesteess if. 0 Sac Loco ya caste cus cal aimee Uy nia Hypsometrical .........- ibid Rio ete ope atone o/s Re rey) Sieve scien eee eae APPENDIX. ‘Gold Hil mining-region; its position and general geology. By Arch. R. Mar- WHS) Sie hea a Re ne nn ae EE MUP AUC aS eid yk a bain The telluride ores of the Red Cloud and Cold Spring mines, Gold ae By B GS NM iy eae ae eg Ss Sl Sw elle wiciee' o's Sie) siterstale eis eerste en Sen LIST OF NEW SPECIES DESCRIBED. FOSSIL PLANTS: \Wi@odlwranclicy nolan, sacs Gse6 sbabuouaoe soceaa boqado.so sade beau socooolosas TRUSS AEGON so seco seen sqqd00 6505 900500 95b005 699600 055050 coas UGES50 Sed CE Pues SMIDSMMN OER cee cosssoaedon00 0506 c95b00 SoH DO Sebo DesoDN esose fee Perish G Ardennes eee ees woe snl snle sain cocoate se ceteie ey Meee et le) natal n a terege NS pidinumi Gold iamimy se sels cs 228 Fie. Shani Backekim@ulonion ek menial ea ( Plate 9, Fig. 1. Natural section, side of Four-Mile Creek ...-.........--.-- 930 (folded.) 2 Fig. 2. Continuation of Kio. 1, down lowa Gulch.....: 22.2: -.-.---- Fy Plate 10, igs. Land 2. Intrusion of voleano rock east of Horseshoe Mountain.... 232 Plate 11, Figs. 1, 2,and 3. Sections at head of Iowa Gulch.........----..--.--. 234 Plate 12. Section through) Weston’s Pass..--.22.252-c0-- so-- S202 sosee eee sees 236 Plate sschishimeluded ani voleanicmoctkaw ssa sat etka = Hee tee cee ae eeeraee ne) eek Plate 14. Block of breccia, Sy een BIR rere tS Miata eye eg ante cte cite eel Plate 15. Dike on Cascade Creek.-.:..- Dre eibaiae apse ie wrestle, Wl) HOR Plate 16. Folding and faulting in cliff on Teocalli Creek... Se Spel cya este IOS Plate 17, folded. View up IDS Hdd GN a Ea UR Me ea eee 256 Big. 1. [Section through Gothic Mountain] -.-.--.- -----.---..-- : N Plate. 18, Fig. 2. [Section across Rock Creek near its JEP IOU ee aaa aaa 4 258 Fig, 3. [Section on Rock Creek south of Snow Mass Mountain]-..- § Hie lp SEC LOM ACLONS PLO AIO BEOT ke. seman mee tama oetaccciee ye ate Plate 19, Fig. 2. Section southwest of Roaring Fork.....-......-.--.------ 263 Fig. 3. Section north from station Soames Sule oeaie pc pam aa Toa Fig. 1. Section from Sopris to Capitol, 9 miles...--....--.---.---- Plate 20, Fig. 2. [Section at right angles to section on Fig. 1]..---.----.--- 265 ‘ig. 3. [Section from Roaring Fork to Frying Pan Creek].....-.-. x CONTENTS. REPORT OF F. M. ENDLICH. Plates. * Facing page— Pyatewle Guvanke dA) seer elect icles doscce Sposdd o¢g0500 Sond S06 epee Eee 277 Fig. 1. Crossing of two veins. Fic. 2. Crossing of two veins. Fig. 3. Crossing of two veins. Fic. 4, Crossing of more than two veins. Fig. D. Drageing of veins. Fig. 6. Dragging and crossing of veins. Plate II (marked 'B) LUE OOD OA SICEAG cae onUneCuoO noceoe occas Siaeicteiereensereetee 278 Fig. 1. ‘‘Horses” in veins. Fig. 2. Ramification of vein. Fig. 3. Ramified termination of vein. Fig. 4. Simple termination of vein. Fig. 5. Vein cut off. Fig. 6. Dislocation of vein. JIBS JNU gS oo5 babes eosoos see ane sdecad cos scueadoceo coagedas dsu0.ccDaCG Gasa.bedc 286 Section through Coleman Gunnell lode, at 130 feet depth. Section through Winnebago lode, 130 feet depth. Section through Bobtail lode, 560 feet depth. ila JW wooded Sb6 5646 os occe noob coueas cade ceases negoodoe aéacon Sa0be0 ac Gddes bel) Section through J. P. Whitney lode, 40 feet depth. Section through Running lode, 100 feet depth. Section throug ch Leavitt ‘lode, 250 feet depth. IBIGRIOW ese Oe eI Ee Aho Sree een Metin a ORS eG MMe TSO Gey GOR Oe MACOS 292 Monte Cristo mine. TeV ete eV ilies aes eee eee sere ae eee alee NE Sone oecra ce mials atotenemtate coterie Beis be eXs) Section through Pelican lode, 80 feet below shaft-entrance. Section through Pelican lode. Section through Terrible lode. PT a hey VoL ate ioe BC ee a are Tue cece aie RS c/s eM - 299 Section through Burleigh tunnel. ! Section through Marshal tunnel. Plate Velie ea Space See ae eed Soe eee ou ky Ree ae erieeimrae everest ei ares oll Section A, from station 53 to station 54. Section B from Princeton Peak through station 51. Section Gi through station 56. * Plate IX. (Not printed. ) Section A, through station 97. Section B, through station 96. Section C, through station 11. Plate XI. (Not printed.) : IED. Re aan ee a a ee re AAS SA dasha ouocdo | Bll Fig. 1. Section in Oil Creek Valley. Fic. 2. Section through Canyon City coal-beds. Plate XIII. (Not printed. ) Pate PR IVie ss sia s ee ie amicte ce Ciciaia ei cceopete a «i= Ssnleis,(elare) o)ss ac ape elciete carer eae tere eerste 339 Section A, from Coochetopa Creek to station 36. Section B, from Coochetopa Creek to station 38. Sections. @SectionsAy trom) Quartz to Runnine eal 2 eee se nee: eee ere eee ) . | Section B, from Gregory Hill to Bates’ HUM o oc cogs See ea f 4 Section C, through Mammoth Bill 220)..0 00... l 282 [pee D, through Bob tari ye eich ce Set es Re Section E, through Kamnsasy amide Gyumie ll stein! Ue yemercrey se See eee ee } Sections through the SanorerdelCristowangy easels sseine sere nese eee eee eee 327 Section A, through station 19. Section B, through station 20. Section C, ideal. Section from east to west, near station 10...... wins Gulag ate bret sid ahaa ae nee ae ea 330 SCHON Hoeypicio I kormonn Owe ne coos tooees doedou poebedeneseo.onsecdoseo oso oDcS 338 Figures. Fig. 1. Diagram illustrating formation of veins ..~..-......---....ce.c--- eee. 7/8) Fig. 2. Vein with combed structure .............. siniciw'nlein)e(eibinte'a(eleiae cee ee eieets 279 CONTENTS. XI Facing page— IPH@ Sp Weil. ococe soos coceoe se0d00 sbecs0 USeSor Soccer GODSas Gone Geaacs Seco nae 975 Fig. Al, COMACIAIONO =o dececo che ces cues coceeu cedous poeoEs Hanoes 6beon suse adee 7 Fig. 5. Conventional signs used in sections of lodes SP Aa w ob Con iaame beste Re aca 287 IPG, @, IGniienseeiiGMm Of WES) .ooc56 séccon esac cocdon sobeds Decbeoceeae onecao ones 307 0G, Zo SOCIO Tit Orel Ciel WAIN coon hocome pee hep See soo oos0 Beene Sc sees aaae 317 His, 8. Stratum of sranite im hornblende-rock _--. -2..+-----.-- 2-2-2222 ---5---- 337 Fig. 9. Pay-Rock Mine at Georgetown, Col. (Refers to page 298) .......--...-. 337 Pigs 10, SeCiiOm M@Ae SURINOM BSS. 5255554000 esocce seaaeo sod soso bseooss onea sand 340 Hie. dl Sechion trom station 26, to station) 20-42. 2. se slsetee eee = oes ne ese eee 344 Fig. 12. Strata of volcanic rocks near Saguache.........--. pas mes ES Pe 345 Fig. 13. Dike of obsidian ..-.-.-... SA Nes cid arava cele raee a hig See Cane Paes MIR eed hs 345 Illustrations. Peiltasiration A. Striation of. eraniteal station 134200 cele eea seca erase oe ces 324 Ilustration B: Fig: a t Red Carboniferous sandstones, capped by volcanic strata........-. 326 g. abe Geological map of the Central City mining-region......_....-.........-..----. 280 Geological map of the Mount Lincoln mining-region ........-.-...-.-....--.-. 302 Sheet showing the division of the district as used in the report, and also the conventional signs used in the geological sections......--...---..-----.----- 305 REPORT ON THE VERTEBRATE PALEONTOLOGY OF COLORADO, BY EDWARD D. COPE. idee ekoxolophodonysaleabusy COpeese ses aerate ce eels aeeiscea oe siee easier 456 Platoon Symlboroden pucco\Copetesacaaaeaeciee sack iecisen cee esos leeieeee ABA ZaelitanotheriumsypLroubiylerdiye esses. sevsleepete eres cise seis ete oa IP ene) IWOL Sharm yaroclom lhueds, O00) soso boas coco coda send oA cdbeos sdeoeo se code ce 484 IPleni@ IY, fSyyaeal borwoyslorn |ONCED, COE) 6boa cede chog ones Suan bec coke cs6ees seoeoees alehl Plate V. Symborodon altirostris, Cope...-.--..-.---------------------------- 484 Plate Vals Symborodon! altirostris, Cope: sss. 222422226452 252 see ce > ocean eee 484 Pate wsllenoymborodoniacer, Copesas sacle eerie ats ee sates Selerejeioeie aisle secs 484 EVateVillt. i Syamborodonvaltiirostris;| Cope) tas- ceases eee a2 eie ecee 2b en NOIOYGO a A DWIKKD = eee sane cca onda HOOUGn Geer cosHeaeeos code 484 Oa YMA OOM OMLACCT a) wo al. acre variates! efayelaye afaicaw cca ie siaiereys saree teres ON THE GEOGRAPHICAL DISTRIBUTION OF THE MOTHS OF COLORADO, BY A. S. PACKARD, JR Hien uCrambus Carpenterellus, Packs. 05> sys sce hte. es Stace cise 3 Ra Aerene) Capenaric CD GUGY)) a= selsiele( oes eels = pany ESE sei 3. Aspilates quadrifasciaria, Pack ....-...-.-..----...----- I 5OO DOOOGS | Aw Buaspilates spinabariaykeacksrs ntsc cls aur emictes ae sereisiee ese se clceerenee Dehasiane lavorasciatar back see niemeescacisen so saiciacels setticelelalele eect Gy Marmoppenysenbessellaal mac kes yeeriuetets aiele tata =o eyaleeeieieye sais siaieie « dopeMacaria| California tay sacks save seis cession isatae oe eerie tate ats dlaietortaeicice SCaulostoma occiduariay racks ee ee as sees eee ES NON RS ers 559 9. Endropia vinosaria, Grote and Rob .----. SCE Eon Saar ere seme lO, Avanos Jisletachiea, (Saitama D382 on eo cogeceoaaacaeaaeo abee HaSaee imepiakuspp ul chery Gro temas esas scieces cis Sie ce easel ise sete U2, allenic aligsny waldo, JPaCleo oes (be cosres cdocad canbe ncceee dacace 13. Hemileuca Diana, Te ke Se ke Son ca EN, No a be 14. Arctia Quenselii, Payk., larva, enlarged twice.....-...--.---------- 15. Lithosia argillacea, Dye outs mn ant sd UMP Ne J SYNOPSIS OF THE FRESH-WATER PIYLLOPOD CRUSTACEA OF NORTH AMERICA, BY A. S, PACKARD, JR. PEs b uC pane eae NS Charny pen eek ert See Veta ARES IA ae cok SN ek ashe wena kianaitae Lit Mei OhiOS Cit BiehVO MOUS somos concen oboe ac bon ecoecOnEoboD oC 622 PAD AN AUP MU SLOLPA DD IS 1 eyets vercpersisie ernie chars [avasnewieva cane eelncy elo steree odie, TOTS Bed Dalia ab over i pee ND TAS UAL SOs oR Re Pr } 4, Limnadia Americana ....-...-. Soa SERIE CAE: Be aonooo noodeH . G22 SepUNTAN AC APA CASSIZIIts sesh eee eae celscis wc cists s)ei alclarssicimjaercisieyeiale GME Sthenilan Oa toric satsc arcctelsyciuis calves siwiain ssleva mise sio sla eine apecais J XII - CONTENTS. Facing page— Plate III. 7. Estheria Clarkii......---.- 2-22-22 2-00 eee e pene ee cee ene cee eeee- 8. Estheria Belfragei.........- sana dooga9 Saocds pondebcgconsce cece 622 9. Lepidurus glacialis .-....- AS Soba eno Scapseacalcnad acas addocc a 10. Apus equalis.... 2.222... 2-2-2 eee eee eee ee ee cree eee eens J Plate lV. 11. Artemia gracilis. ...... 22. 0-2. -- +--+ 22 cee ee ee ee ee ee ee eee ae 12. Branchipus Coloradensis.......---.+--------+--+----------+--- 622 13. Streptocephalus Texanus ......-.--.:---------------:---------J 4 REPORT ON THE AMPHIPOD CRUSTACEANS, BY S. I. SMITH. Plate I. Hyalella inermis. ) 1. Female; lateral view, enlarged 16 diameters.-.-.--... 2. Male; terminal portion of one of the second pair of thoracic legs seen from the outside, enlarged 50 diam- | eters. Hyalella dentata. 3. Adult male; terminal portion of one of the second pair of thoracic legs, seen from the outside, enlarged 50 \ 612 diameters. f S 4. Young male; 3.7™™ long; terminal portion of the corre- | sponding leg, enlarged 50 diameters. 5, Adult male; maxillipeds, seen from above, enlarged 80 80 diameters. , 6, Adult male; one of the first pair of thoracic legs with its epimeron, seen from the outside, enlarged 50 diam- eters. Plate II. Gammarus robustus. | 7. Female; lateral view, enlarged 5 diameters. ......-..-- 8. Male; flagellum of one of the antennz, enlarged 25 diameters. 9. Male; terminal portion of one of the first pair of thor- acic legs, seen from the outside, enlarged 25 diam- eters. 10. Male; same portion of one of the second pair of thoracic legs, enlarged 25 diameters. 11. Female; terminal portion of one of the. first pair of | 612 thoracic legs, seen from the outside, enlarged 25 diam- " eters. 12. Female; same portion of one of the second pair of | thoracic legs, enlarged 25 diameters. Gammarus limneeus. 13. Male, from lake near Long’s Peak; terminal portion of | one of the first pair of thoracic legs, seen from the outside, enlarged 20 diameters. | 14. Male, from the same locality; same portion of one of the second pair of thoracic legs, enlarged 20 diameters. J SKETCH OF THE METHODS OF SURVEY, BY JAMES T. GARDNER. Sketch showing the primary and secondary triangulation of 1873....-.....----.-- 627 THE ELEVATIONS OF CERTAIN DATUM-POINTS, BY JAMES T. GARDNER. Map showing the railroad and canal lines used in the determination of elevations 660 Preliminary map of Central Colorado, showing the region surveyed in 1873..... 682 ‘\ WOOD-CUTS IN TEXT. REPORT ON THE DIPTERA, BY C. R. OSTENSACKEN. WanlexvotBiloroce pial aicpiclei<)s;ssietsin chasis Sate, See Cee ete ey se es te re ee oe eee 564 DESCRIPTION OF A LERNEAN CRUSTACEAN, BY A. S. PACKARD, JR., M. D. Achitheres | C arpemterie coe. cci seijesisces cee sisiewic cop cmecereetes Ba Hr ale neha case 5a) Cis THE TELLURIDE ORES OF THE RED CLOUD AND COLD SPRING MINES, GOLD HILL, BY B. SILLIMAN. A, porphyry-dike, with B, C, veins with gold and tellurium ores ..... Buoy eiapatata 688 LETTER TO THE SECRETARY. WASHINGTON, July 1, 1874. Sir: In accordance with your instructions, I have the honor to present for your approvalthe Seventh Annual Report of Progress of the United States Geological Survey of the Territories for the fiscal year commencing July 1, 1873, and ending June 30, 1874. In my letter to the Secretary of the Interior, dated January 27, 1873, (Ex. Doe. No. 166,) inviting his attention to some views in behalf of an appropriation for continuing the survey of the Territories, and his recommendation of the same, the plan of operations for the ensuing season was marked out in general terms as follows: For the last two years the survey has operated about the sources of the Missouri and Yellowstone Rivers; but the expenses of transportation, subsistence, and labor are so great that it seems desirable to delay the further prosecution of the work in the Northwest until railroad-communication shall be established. The Indians, also, are in. a state of hostility over the greater portion of the country which ‘remains to be explored. It seems. desirable, therefore, to transfer the field of labor, for the coming season, to the eastern portion of the Rocky Mountain range, in Colorado and New Mexico. I propose to commence with the southern limit of the belt of the survey of the fortieth parallel, so successfully completed under the direction of Mr. Clarence King. The vorthern limit of the area marked out is latitude 40° 30’; the western limit, the east bank of the Green and Colorado Rivers; the eastern limit, the one hundred and third meridian west of Greenwich, extending the belt southward to the south line of the United States. There is probably no portion of our continent, at the present time, which promises to yield more useful results, both of a practical and scientific character. This region seems to be unoccupied, at this time, as far as I am aware, by any other survey under the Government, and the prospect of its rapid development within the next five years, by some of the most important railroads in the West, renders it very desirable that its resources be made known to the world at as early a date as possible. In accordance with the recommendation of the Secretary of the In- terior, an appropriation of $75,000 was made for the systematic survey of Colorado, and, at as early a date as the season would permit, the party reached Denver. This place formed our starting-point for the various portions of the territory which had previously been marked out for the season’s work. Early in the winter, the area to be surveyed in Colorado was divided into three districts,and a preliminary map was constructed, based on the land-surveys of those portions concerning which there was any definite knowledge. We found that none of the existing maps were of any great service in the more elevated portions of Colorado. The area to be surveyed comprised the eastern portion of the mountainous part of Colorado, and it was separated into three dis- tricts: North, Middle, and South districts. 1Gs 2 GEOLUGICAL SURVEY OF THE TERRITORIES. As soon as suitable preparations could be made at Denver, three well- equipped parties were assigned to these areas. Each party consisted of a topographer, an assistant topographer, a geologist, two packers, and a cook. There were usually two or three others attached to each party as general assistants or collectors in natural history. There were also three other parties, with very important duties to per- form: First, a party under Mr. James T. Gardner, to carry the primary triangulation over the entire area to be explored, thus connecting and harmonizing the work of the first three parties; secondly, the photo- graphic party, under Mr. Jackson, which also passes over the entire field, gathering such information and procuring such views as will be useful to all the other parties and to the public generally ; to this party are also attached one or two naturalists or collectors; thirdly, the quartermaster’s party, which furnishes supplies to all the others. Itis very important that the working parties in the respective fields shall lose no time from their proper duties, and, with this systematic arrange- ment, they may work through an entire season without the loss of even aday. During the present season (1874) there will probably be a party, consisting of a topographer and the necessary assistants, under the im- mediate direction of the chief geologist, which will make special studies of some of. the more complicated areas already examined during the last year. This will render the final work more complete.. It will be seen, therefore, that the organization is complete and com- pact, and prepared for the systematic work for which it is intended. It may be enlarged at any time to meet the needs of the Government. The addition of one or more parties at any time does not affect the integrity of the organization. Each one of the parties is complete in itself, and may be sent to any portion of the public domain as the needs of the Department may require. The divisions operating in the districts assigned during the season of 1873 were denominated for convenience the First or Middle Park divis- ion, Second or South Park division, and the Third or San Luis division. The Middle Park division was directed by A. R. Marvine, assistant geologist, with G. R. Bechler, topographer, and S. B. Ladd, assistant topographer. HK. T. Luce and 8S. H. Nealy were attached to this division for a portion of the season as general assistants. The following interesting abstract has been prepared by Mr. Marvine of the work of his division, which will apply, for the most part, to the others. The area surveyed by the Middle Park division of the United States Geological and Geographical Survey of the Territories during the season of 1873 comprised an area of about fifty-six hundred square miles, approx- imately in the form of a rectangular belt, its eastern end resting on the plains near Denver City and stretching westward across the main chain of the Rocky Mountains, including the Middle Park. The methods of survey were precisely the same as in the other divis- LETTER. - 3 ions of the party; the main portion of the work being done from topo- graphical stations situated upon the most commanding points within the region, together making a system of secondary triangles within the pri- - mary system. From these commanding points, of which seventy, averag- ing about eight miles apart, were occupied during the season, both drain- age-sketches expressed in contours, and perspective profile-sketches, were made by the topographers, and angles, both horizontal and vertical, taken to all the intersections of streams, their principal crooks and bends, all points, spurs, saddles, and sudden changes of slopes; which, with similar angles taken from adjacent stations upon the same points, served to fix their positions and elevations; and with the thousands of points thus fixed during the season with an exceedingly close approxi- mation to absolute truth, the map is filled in from sketches made by the topographer. The geologist, meanwhile, has made his own detailed and special studies and sections along the route traveled, or on special trips for this purpose; and this detail he generalizes from the higher stations made by the topographer, obtaining extensive views from them, from which he can trace his formations across the country; and with the locations and directions furnished by the topographer more accurately and readily than he can obtain them himself, he can secure data by which he can readily color a general geological map upon his return. Indeed, next to entering the field with a finished topographical map of the region to be examined, a thing as yet impossible in our West, the union of topog- raphy and geology in one and the same party best furnishes the data for a realization of the full value of the otherwise more or less discon- nected observations of the geologist; and equal benefits accrue to the topographer, for mannerism and inexpressive effects are inevitable results when a topographer sees but the surface of a country and under- stands not its anatomy. Association of topographer and geologist thus leads to benefits to each, and is certainly a great advantage to the sys- tem of field-working now followed by the survey. The first chapter of his report deals with the main drainage-systems and principal topographical features of the whole district, which mate- rial is greatly supplemented by the report Mr. Ladd has prepared upon the means of communication, elevations, distribution of timber, grass- lands, and population. The Sedimentary rocks underlying the great plains are all thrown up along the mountain-base, with their edges exposed. The formations thus exposed form the subject of Chapter II, where they are treated in order from the lowest, the Triassic, resting directly on the Archean rocks, through the Jurassic, Cretaceous, and Lignitic (Upper Cretaceous or Eocene,) with a few facts about the more recent gravels and lavas. The detail-characters of the lower beds are exhibited (Plate I) in detail- sections made at six points along the front of the mountains, while their structural features—the more simple fold of the south, the more com- 4. GEOLOGICAL SURVEY OF THE TERRITORIES. plex echelon-folds of the north, and the changes between—are shown (Plate II) by cross-sections at seventeen points along the mountain-front. A map to show the distribution of the Lignitic coal-openings, with rail- roads, &c., is also given, and attention paid to what is at present knowa concerning the usefulness of these coals. The mountains are composed of a great series of metamorphic Mes gneisses, and granites of pre-Silurian age, (with minor masses of erupt- ive rocks,) all thrown into a complex system of folds, which are very difficult to trace on account of the absence of permanent features in any one horizon; metamorphism so frequently obscuring what distinctive features certain strata may possess for a little distance. A single, indeed many, season’s work, would be insufficient to unravel the problems in structure, but more especially in metamorphism, here presented. Even such material as is here presented cannot be made fully available until carefully plotted on the final map. In the mean while, how- ever, Mr. Marvine has prepared a provisional geological map of the eastern slope of the front range, where these rocks were best studied, which shows their general structure, accompanying it with a brief chap- ter on the more general phenomena here observed. The Sedimentary rocks of the Middle Park form the subject of Chap- ter IV, their distribution being shown on the accompanymg map, and their structure by the five cross-sections on Plate III, together with minor sections and figures. The relations between the geology and the topography is particularly referred to. The more interesting geological features here observed are: that the Cretaceous rocks seem to be the oldest Sedimentaries, resting directly on the Archean, a decided uncon- formability of deposition between the Cretaceous and Lignitic formations, proving that a small east and west anticlinal fold, which occurs along the Lower Grand River in the Park, was formed at the close of the Cre- taceous, and before the more extended Rocky Mountain uplift ; the inclination of probably post-Tertiary lake-beds, pointing to a compara- tively recent slight continuation of this uplift; and interesting glacial phenomena. The energy and devotion to the work displayed by Mr. Marvine merit the highest commendation, and the results so admirably brought out in his report, as shown by the above short résumé, are but the prom- ise of the future. The map of the first district, prepared by Mr. Bech- ler, with the assistance of Mr. Ladd, will be engraved the present sum- mer, and will more than sustain the high reputation which he gained by his labor in the Snake River district during the season of 1872. During the field-season of 1873, Henry Gannett was topographer in charge of the Middle or South Park division. This party consisted, during the greater part of the season, of eight men, Dr. A. C. Peale, division geologist; W. Rush Taggart, assistant division geologist; Henry W. Stuckle, assistant topographer; J. H. Batty, naturalist; two packers ; and a cook. - LETTER. 3 The area assigned to this party is limited on the north by the para!- lel of latitude of 39° 15’; on the south by the parallel of 38°30’; on the east by the eighth guide-meridian of the land-survey, and on the west by the one hundred and seventh meridian. The party left Denver on May 29, and commenced field-work on June 1, and ended October 21. The secondary triangulation and the topograph- ical work of the district were completed, with the exception of a part of the country in the immediate neighborhood of the North Fork of the South Platte, and a small area on Ten-Mile Creek, which will be completed early this season. In the prosecution of the topographical work, ninety-six stations of sufficient importance to be numbered were made, besides a large num- ber, twenty-five or thirty, of minor importance, for obtaining local details, &c.; nine peaks exceeding 14,000 feet in elevation, and a very large number of peaks exceeding 13.000 feet, were measured as accur- ately as possible by barometer or theodolite. All the important passes in the. mountain-ranges within this district were examined. During the winter and spring, in the office, Mr. Gannett has made a map on a scale of two miles to one inch, in 200-foot contours of the area worked, and has also reduced the hypsometric work of the season. He has prepared for the press a new edition of the “ Lists of Elevations West of the Mississippi River,” (which will contain about 75 octavo-pages, ) and has prepared a short geographical report, and a short memoir on the results of the trigonometric leveling carried on during the past season. Doctor Peale, the geologist of the South Park division, was assisted by Mr. W. R. Taggart, and their plan of work was as follows: One per- formed the detailed work at or near camp, such as making measured sections, collecting fossils, &c., while the other accompanied the topo- grapher to the station selected for the day’s observations, which was generally the highest point in the immediate region. At the latter place, the boundaries of the geological formations were defined in colors on a drainage-sketch; this was, of course, based on previous detailed work. In this manner, the geologist was able to make much more per- fect results than he could otherwise have done. The amount of labor thus performed by this party was very great, and reflects great honor on the survey. The labors of Mr. J. T. Gardner during the season of 1873 have shown the importance of careful instrumental observation in raising the stand- ard of the topographical work of the survey. His methods will be explained more fully by himself in a subsequent portion of this report. The primary triangulation during the season of 1873 covers about 17,000 square miles. Over two-thirds of this area the triangies are completed, and the third angles of the remaining triangles will be ob- served this season. Sixteen stations were visited and the angles at them repeatedly 6 GEOLOGICAL SURVEY OF THE TERRITORIES. observed. Thirty-two more points were located from the primary sta- tions by cuts. Forty-seven closed triangles were used in the adjustment of the sys- tem. Their mean error of closure, after reduction for spherical excess, is 10”.3, Two of the principal stations were accurately located in latitude and longitude by the United States Coast Survey. Azimuths were observed at five of the stations. The system of triangles rests upon a base about six miles long near Denver. This was twice measured with a steel tape under twenty pounds strain and the temperature taken every five minutes. A check- base will be measured this year. A secondary triangulation, resting upon this primary, was carried by the topographers over the same area. The primary triangles range from thirty to sixty miles in the length of their sides, while the secondary average eight miles. Mr. A. D. Wilson, a topographer of large experience, directed the San Luis division. His method of work was, on arriving at his field of labor, to select a peak from which, in his judgment, he could see the surround- ing country to the best advantage, and from this also to choose other points in advance. These points or stations were carefully located bya system of secondary triangles, connecting directly with the primary- triangulation points, several of which were visited. From each station were taken angles, both vertical and horizontal, to all peaks, passes, ends of spurs, streams, junctions of roads, and all recognizable features of the country. The drainage-sketches and instrumental observations were made by Mr. Wilson, while the assistant topographer, Mr. Chit- tenden, was employed in making profile-sketches and observing the barometer. Barometric observations were made at all stations, camps, passes, valleys, and places of note. The district thus surveyed em- braced an area between longitude 104° 30/ and 107° and latitude 379 50/ and 38° 45’, of about eight thousand four hundred square miles. Within this district ninety-nine regular stations were made by Mr. Wilson, be- sides ten or twelve by the assistant, which give an average distance from station to station of seven or eight miles. — According to instructions received, Doctor Endlich, geologist for the San Luis division, visited,on May 17, 1873, the mining-regions of Gilpin, Bowlder, and Clear Creek Counties in Colorado, remaining there until July 1. During that time all the important mines in operation were personally inspected, with a view of determining their geological and nineralogical relations among themselves as well as with reference to the geognostic formations surrounding them. On July 3, the San Luis division, to which he was attached as geologist, took the field, and remained in active field-service until October 5. Eight thousand four hundred square miles were surveyed topographically and geologically, and particular attention paid to the agricultural and mineralogical resources of the country traversed. LETTER. tf Geological work and topographical observations were carried on in harmony with each other, so that the geologist was able to prepare a map showing, with a considerable degree of accuracy, the horizontal distribution of formations throughout the district assigned. The topographical stations were almost invariably accepted by the geologist as suitable for his examination, and a co-operation was thus secured that must render better results than can be obtained by any other method which may claim to cover an equally large area. During the winter of 1873~74, the report upon the sections examined was worked up from the notes taken in the field. A large map, showing the distribution of formations, was prepared, and a report submitted. This report is divided into four chapters and an appendix; the first chapter treating of the mining-regions explored; the three next of the geology of the San Luis district, which was divided into three sections in order to facilitate descriptions and the comprehension of localities. In the appendix are contained “ Mineralogical notes,” describing two new spe- cies of mineral, and the occurrence of native tellurium—being the second locality in the world where it occurs—and a “Catalogue of minerals found in Colorado Territory,” enumerating over one hundred and fifty species, by far more in number and locality than had ever be- fore been reported from that Territory. Experience in the field has shown most clearly the necessity of com- bining topographical observations with geological research. Of all maps that are of importance and great use to the geologist, contour-maps must be preferred. He may note by his observations, and express by means of vertical sections, the arrangement of strata throughout a cer- tain mountain, ridge, or range, and the contour given on the map will then greatly facilitate his work by enabling him to define more correctly than in any other way the limits of the successive strata. From the stations selected, the geologist can indicate the points important for his work; the topographer can locate these points and reproduce them on the maps which are plotted during the winter follow- ing the field-work, thus giving to the former data that must be in- valuable to any one who appreciates precise work, even when done on so large a scale. Mr. W. H. Jackson performed his duties in the field with his usual success. His triumphs in the mountain regions of Colorado are already well known all over the country. The panoramic views of the mountain- peaks have been of great value to the topographer as well as the geolo- gist, and have proved of much interest to the public generally. Mr. W. H. Holmes also made numerous panoramic sketches from the high peaks used as primary stations. The value of the present report is greatly increased by the beautiful and accurate sketches and sections from the results of his skill in the field and in the office. His knowledge of structural geology is such that he merits the position of assistant geologist. 8 GEOLOGICAL SURVEY OF THE TERRITORIES. Mr. James Stevenson acted as quartermaster and executive officer of the survey, and performed the labors incident to his department with judgment and fidelity. | Mr. Robert Adams, jr., of Philadelphia, acted as assistant quarter- master, with entire satisfaction. By the kind permission of General Sherman and General Ord, Lieut. W. L. Carpenter, U. S. A., accompanied the survey as naturalist, and the result of his zeal in the work is well shown jin subsequent portions of this report. Prof. W. D. Whitney, of Yale College, rendered most valuable assist- _ ance to Mr. Gardner in his geographical work, for the months of July and August, without compensation from the Government. Mr. Leo Lesquereux is permanently attached to the survey as paleon- tologist. He has just completed a memoir on the fossil flora of the Dakota group, with thirty plates, and is now preparing a second me- moir on the flora of the Lignitic group, which will contain over sixty plates. This work will be ready for publication in about six months. Mr. F. B. Meek, the eminent paleontologist, is also a member of the survey, and has nearly completed his most valuable, but long delayed, memoir on the invertebrate fossils of the West, which will go to press the present summer. It will contain forty-five beautifully-engraved plates, all of which are now finished. Prof. C. Thomas will remain in charge of the office, superintending the printing of the reports while the main party is in the field. The survey is under obligations for most valuable papers from Dr. A. S. Packard, S. I. Smith, A. E. Verrill, H. A. eee and Baron R. Os- tensacken. J have only words of commendation for all the members of the survey for their devotion to the work. To the officers of the various railroads in the West, to the citizens of Colorado, and to the press all over the country, the survey is under many obligations. HISTORY OF THE SURVEY. A brief history of the survey may not be out of place in this connec- tion and at the present stage of its progress. In the spring of 1867, when the Territory of Nebraska was admitted into the Union as a State, Congress passed a bill setting apart the unexpended balance of the ap- propriation for the legislative expenses of the Territory for the purpose of procuring a geological survey of the State. The amount proved to be about $5,000, and the summer of 1867 was occupied in making an examination of the eastern portion of the State. A preliminary report was published in the annual report of the Commissioner of the Land-Office for that year. Some four years after, a final report, in octavo, was printed by Congress. In the spring of 1868, $5,000 more was appropriated, and the survey LETTER. 9 was extended into the Territory of Wyoming, along the line of the Union Pacific Railroad. A second annual report was made as the re- sult of this brief preliminary examination. But it was not until the spring of 1869 that the survey received its present form. At the close of the session a clause was added to the sundry civil bill, in the follow- ing words, ‘‘ For the continuation of the geological survey of the Terri- tories of the United States, by Prof. F. V. Hayden, ten thousand dollars, to be expended under the direction of the Secretary of the Interior.” By direction of the Secretary of the Interior a geological reconnaissance was extended along the eastern portion of the Rocky Mountain range, from Cheyenne to Santa Fé, N. Mex., and in the winter of 1869~70 an annual report was published containing the preliminary results. In 1870 the appropriation was increased to $25,000, and the season was occupied in exploring portions of Wyoming Territory. In 1871 $40,000 was ap- propriated for the continuation of the survey, and by direction of the Secretary of the Interior the work transferred to the interesting region about the head-waters of the Yellowstone and Missouri Rivers. To this expedition one topographer was attached. In 1872 the work was continued in that region, with an increased ap- propriation of $75,000, with two large parties and a full corps of topographers and geologists. The result was a still more detailed ex- ploration of previously little-known portions of Montana and Idaho, especially about the sources of the Yellowstone, Missouri, and Snake Rivers. A preliminary account of the results of the survey was given in the annual report for 1872. During the season of 1873 the geographical, as well as the geological, corps was more complete and better prepared for its duties than at any previous period. The Territory of Colorado was assigned to it as the field of its labors; and the report of progress, which contains many of the important results, is now ready for publication. THE PUBLICATIONS OF THE SURVEY. The plan of publication of the results of the survey has been matured gradually, and it is believed that it meets the requirements of the scien- tific men of the country, as well as the people at large. The publica- tions are divided into three principal classes. The first class consists of the annual reports, or reports of progress. These will be issued every year, and will give early information of the progress of each season’s labors. They will contain much new and im- portant matter. The second class comprises a series of ‘‘miscellaneous publications” on different subjects connected with the West, which are important contri- butions, but are to some extent compilations, and usually issued in smaller editions. They consist of elevations, meteorological observations, ac- counts of the botany, ornithology, entomology, catalogues, &ec.; all based on the labors of the survey. 10 GEOLOGICAL SURVEY OF THE TERRITORIES. The third class will embrace the more technical and matured results, and will be issued in quarto form, and are designed more especially for libraries and men of science. These volumes will be elaborately illus- trated. : To meet the wishes of some of the collaborators of the survey, who - desired the early publication of important results, a bulletin was pub- lished during the past winter and two numbers issued. This will be continued from time to time as circumstances may require. The following is a list of the publications of the survey up to the present time : 1. First, Second, and Third Annual. Reports of Progress for 18676869, 261 pages, Svo. 2. Fourth Annual Report of Progress for 1870, (Wyoming, &c.,) 511 pages, 8vo., with twenty-two wood-cut illustrations. 3. Fifth Annual Report of Progress for 1871, (Montana, &e.,) 538 pages, Svol, with sixty-four wood-cuts, two plates and five maps. 4, Sixth Annual Report of Progress for 1872, (Idaho, &c.,) 844 pages, 8vo., with sixty-eight wood-cuts, twelve plates and five maps. 5. Seventh Annual Report of Progress fur 1873, in process of publi- cation. 6. Final Report of the Geological Survey of Nebraska during the year 1867, 264 pages, 8vo., with a colored geological map and eleven plates of Carboniferous fossils. 7. Supplement to the Fifth Annual Report on the Fossil Flora of the West, by Leo Lesquereux, 22 pages, 8vo. . 8. Synopsis of New Vertebrata from the Tertiary of Colorado, obtained during the summer of 1873, by Prof. E. D. Cope, 19 pages, 8vo. Miscellaneous publications. 9. No. 1.—Lists of elevations in that portion of the United States west of the Mississippi. Collated and arranged by Henry Gannett, assistant, pp. 47, 8vo. Second edition. A third edition of this impor- tant paper will be issued shortly, very much enlarged and improved. 10. No. 2.—Meteorological Observations during the year 1872; Utah, Idaho, and Montana; prepared for publication by Henry Gannett, assist- ant, 120 pages, 8vo. 11. No. 3.—Hand-book of the Ornithology of the Territories of the Northwest, by Dr. Elliott Coues, U.S. A., (in press.). 12. No. 4.—Synepsis of the Flora of Colorado, by Prof. T. C. Porter and John M. Coulier, 180 pages, 8vo. ; 13. No. 5.—Catalogue of Photographic Negatives belonging to the survey, by William H. Jackson, 85 pages, 8vo. 14, No. 6.—Meteorological, Observations, taken by the survey during 1873, 70 pages, 8vo. LETTER. 11 Bulletins. 15. Bulletin No. 1—Pliocene Vertebrate Paleontology of Northern Colorado, Cope, 28 pages, 8vo. 16. Bulletin No. 2.—Vertebrate Paleontology, Cope; Cretaceous Flora, Lesquereux, Acridide, Thomas; Geography, Elevations, &c., Gardner; 27 pages, 8vo. Quarto publications. 17. Vol. I. Contributions to the Extinct Vertebrata of the Western Formations, by Prof. Joseph Leidy, 358 pages, with thirty-seven plates. 18. Vol. If. The Vertebrataof the Cretaceous Formations of the West, by Prof. E. D. Cope. 19. Vol. III. The Vertebrata of the Eocene Formations of the West, by Prof. E. D. Cope; 40 plates. 20. Vol. IV. The Vertebrata of the Miocene and Pliocene Forma- tions of the West, by Prof. E. D. Cope; 40 plates. 21. Vol. V. Synopsis of the Acridide of North America, by Prof. Cyrus Thomas; 258 pages, 4to, one plate. 22. Vol. VI. Contributions to the Fossil Flora of the Cretaceous and Tertiary Formations of the West, by Prof. J. 8. Newberry ; 60 plates. 23. Vol. VII. The Fossil Flora of the Cretaceous Formations of the Western Territories, by Prof. Leo Lesquereux; 30 plates. 24, Vol. VIIL The Fossil Flora of the Tertiary Formations of the Western Territories, by Prof. Leo Lesquereux ; 60 plates. 25. The Fossil Invertebrata of the Western Territories, by BP. B. Meek; 45 plates. 26. Seecins, profiles, and other illustrations of the Geology of the Western Territories explored by the survey, with descriptive text by F. V. Hayden. in three parts. Part 1 contains about 75 plates of sec- tions, &c. Part 2, 52 plates of scenery, prepared by the Albertype pro- cess from the photographs of the survey. Part 3, 37 plates of the Hot Springs, Geysers, &c., of Montana. A small edition of the profiles, sec- tions, &c., one hundred copies have been issued without the text. Maps. 1871. 1. Yellowstone Lake. 2. Lower Geyser Basin of Firehole River. 3. Upper Geyser Basin of Firehole River. 4, Yellowstone National Park. Notes by A. Schonborn. 5. Parts of Idaho, Montana, and Wyoming Territories. (Prelim- inary map for field use.) 1872. 6. Lower Geyser Basin of Firehole River. (Scale, six inches to the mile.) . Upper Geyser Basin of Firehole River. (Scale as above.) 8. Heury’s Lake, Idaho. 4 12 GEOLOGICAL SURVEY OF THE TERRITORIES. 9. Shoshone Geyser Basin, and Lake. 10. Parts of Idaho and Wyoming about the heads of the Snake River. (Scale, five miles to one inch.) (Prepared by G. R. Bechler.) 11. Parts of Montana and Wyoming about the heads of the Yel- lowstone, Gallatin, and Madison Rivers. (Scale, four miles to one inch.) Drawn by Henry Gannett from field-notes by A. Burek. 12. Part of Colorado, based on the United States land-survey. 1873. Compiled for field use. No. 11, containing the complete list of the Ornithology of the North- west, is passing rapidly through the press. Nos. 14, 18, 19, 20, 22, 23, 24, 25, and 26 are either ready for the press or in an advanced state of preparation, and will be issued within a year. : The map of a portion of Montana and Wyoming Territories, embrac- ing most of the country about the sources of the Madison, Gallatin, and Yellowstone Rivers, in contour lines of 190 feet, and on a scale of four miles to one inch, can hardly be said to be published. yet, only a few copies having been issued. The data for this map were collected in the field by Mr. Adolph Burck, assisted by Mr. Henry Gannett. In the office it was completed by Mr. Gannett. The following explanation in regard to the metbod and purpose of the map will certainly be suffi- cient for all fair-minded men. : The topographical work was carried on mainly from a meandered line, (meandered with compass and odometer.) Points along the line were located by angles, using the meandered line as a base-line. Much topography, also, was done from mountain-peaks, with gradienter and compass. In addition to this, short bases were measured in several localities with steel-tape, and connected with the topographical work, to serve as checks, and the whole was checked at the camps by sextant observations for latitude and time, the longitude being determined by chronometer, the rate of which was repeatedly checked. The location of the contours was controdlled by barometric observa- tions, vertical angles with the gradienter, and slope angles with the clinometer. Vrhile not pretending to be an accurate contour map, which it would be useless to attempt to make in a hasty reconnaissance, it does assume to express, with considerable accuracy, the form of the country, in its vertical as well as in its horizontal features. The system of plotting maps with elevation curves is of the greatest importance for practical geological studies of any locality or country that has been surveyed in that way. It is evident that wherever sedi- mentary formations occur the curve system greatly facilitates the work of the geologist. Geological maps, if carefully made, will always rep- resent more or less scalloped curved lines, denoting the boundaries of the different geological formations, and it is therefore apparent that LETTER. . 13 whenever the stratigraphical conditions have been observed, and are known, a map showing the elevation curves will enable the geologist to recognize, with great accuracy and certainty, details of geological distri- bution that otherwise would require considerable time and labor to work out. In working out sections the curves are of importance, giving the geologist a means by which to give a correct diagram of the line of country through which he has made his section, and furthermore fur- nishes him valuable data facilitating the measurement of strata. The map of the sources of Snake River and its tributaries, on a scale of five miles to one inch, is a most valuable contribution to the geogra- phy of a portion of our western country, previously almost entirely unknown. The great amount of faithful, conscientious labor bestowed upon it by Mr. Bechler, both in the field and in the office, is so evi- dent that I need not speak of it in detail. An edition of the drainage portion, with the brush-work omitted, will be published during the sum- mer, Showing the geological formations with colors, by Professor Brad- ley. During the summer of 1872 Mr. Bechler resurveyed the Upper and Lower Geyser Basins of the Firehole River; and the two charts, on a scale of six inches to one mile, have just been very beautifully en- graved on stone by Mr. Bien. It is believed that all unkind criticisms of the labors of other scien- tific men are out of place in an official report, and in no instance will they receive the sanction of the geologist in charge. Each assistant is held responsible for the correctness of his statements in his report, and ‘it is presumed that his love of truth is superior to his personal feelings. Problems are arising and wiil continue to arise about which there will be difference of opinion among true men of science. We shall accept the verdict founded on the evidence as soon as it comes fairly before us, regardless of our preconceived opinions. In performing so great an amount of field-work, and in publishing so freely and rapidly as we do, an unkind critic may find defects in our reports which might not have existed with delay; but it seems not only necessary but eminently desirable to bring our results before the public at as early adate as possible. Should mistakes occur, (and they cannot reasonably be avoided,) we hope to correct them in future publications. I regret that my own report has not been more carefully prepared this season, and that I have been obliged to omit several chapters in which I had intended to discuss some of the more important problems in the geology of the Rocky Mountain region. The discussion of the Lignitic group will be continued by Professor Lesquereux. His views in regard to the age of this group are well known, and it seems probable that they will be sustained by future evi- dence. The stratigraphical evidence on this subject, so far as Colorado is concerned, will be subjected to the closest scrutiny the present season. The present report of progress is submitted with the belief that it is 14 GEOLOGICAL SURVEY OF THE TERRITORIES. a valuable contribution to our knowledge of the geography, geology. and natural history of a very interesting portion of the public domain. I would again extend my cordial thanks to the Secretary of the Interior and to Hon. B. R. Cowen, Assistant Secretary, for their continued aid and encouragement in advancing the objects of the survey. Very respectfully, your obedient servant, F. V. HAYDEN, United States Geologist. Hon. C. DELANO, Secretary of the Interior. PIR TE 6p. EERE GEOLOGY, MINERALOGY, AND MINING INDUSTRY. REPORT OF F. V. HAYDEN, U. 8. GEOLOGIST. QHEPAV PE Bik i: REMARKS ON SURVEY—THE GEOLOGICAL FEATURES OF THE EAST SLOPE OF THE COLORADO RANGE OF THE ROCKY MOUNTAINS, FROM CACHE A LA POUDRE RIVER SOUTHWARD TO PIKE’S PEAK. In the third annual report of the survey for 1869 I described with some care the geological features of the east slope of the Rocky Moun- tains, from Cheyenne to Santa Fé. My investigations were more par- ticulairy confined to the sedimentary formations as they are shown by their upturned edges along the immediate eastern base of the range. In this chapter I can do but little more than confirm the accuracy of the statements made in that report, and add a few new facts, referring the reader to the more detailed reports of Mr. Marvine and Dr. Peale. Although the sedimentary rocks along the flanks of the mountains are of great interest, yet the general outline of their geology is compar- atively simple. The vast plains to the west of Cheyenne are covered with the drab-yellow and light-gray sands, marls, and clays of the great fresh-water lake deposit, known as the “bad lands,” (Mawvaisses terres,) and may be Miocene, or Pliocene, or both. This entire group of deposits juts up against the foot of the mountains, not conforming to the older beds, and in a horizontal position or inclining not over 5°. The Union Pacific Railroad passes uninterruptedly across this deposit from a point east of Grand Island, on the Platte, to the margin of the first range. AS we pass southward from the railroad this lake-deposit soon thins out and disappears, and the full series of the older sedimentary rocks known in this region are exposed in their order of sequence. The fresh-water Tertiary deposits not conforming with the older rocks and jutting up against the sides of the front range almost to the summit, necessarily conceal the latter over a very long distance. For one hun- dred miles or more they are not visible, only as the former have been washed away, and for a considerable distance north of the Laramie River the fresh-water deposits conceal all the older beds, and rest upon the gran- ites direct. About four miles south of a locality known on the maps as Spottswood Springs, the Lignitic beds begin to be revealed in the valleys of the little streams, and very soon the fresh-water deposits entirely thin out. So faras I have been able to ascertain, the older sedimentary strata perfectly conform, and we have here a series of uplifted ridges, showing all the sedimentary rocks of the region up to the Lignitic group inclusive, with remarkable distinctness. I am not certain that we have well- defined Carboniferous beds south of the railroad. Along the line of the railroad, between Hazard Station and Granite, the limestones of Car- boniferous age are exposed to a limited extent. So far as I have ob- 268 15 GEOLOGICAL SURVEY OF THE TERRITORIES. served, rocks of this age do not occur again until we reach Colorado Springs, south of the railroad. The brick-red group rests on the Meta- morphic rocks, and, starting from the granite nucleus, we pass across the upturned edges of the sedimentary beds, as they incline from the east slope of the mountains at various angles. We have been in the habit of calling the brick-red beds Triassic; but it is by no means proven, and as there are red beds of similar mineral character in the well-marked Carboniferous group below, and the Jurassic above, I have sometimes been disposed to refer them to one or the other, or to both, and regarding the Triassic as wanting. The thickness of the red group as exposed at different localities varies considerably, and it is oftentimes difficult to decide whether the difference is due to original deposition, or whether the beds have been crushed together, or concealed by newer form- ations. If the Triassic group is wanting in this region I cannot point out any locality where there is any marked unconformability between the Jurassic and the Carboniferous, and this fact might be used to favor the belief that the red group is Triassic. Above the red group is a series of variegated beds, which seem never to be absent along the margins or flanks of the eastern ranges of mountains from the nerth line of our territory to Mexico. North of the railroad the Jurassic maris are often filled with characteristic fossils, but south of that point they disap- pear, and they have not yielded any positive paleontological proof of their age to the numerous explorations as far south as Santa Fé. The litho- logical characters of the group, however, are well preserved, although from the line of the railroad far south to New Mexico the group is thinly represented. Above the Jurassic is a fair representation of the Creta- ceous series. No.1, or the Dakota group, is well shown and is always characteristic, though seldom containing any organic remains, but the other divisions, which are so well defined farther north, are here very obscure. The geologist studying these beds in their southern extension first, would hardly think of separating them into the five well charac- terized divisions of the Northwest. To one who has carefully studied the divisions along the Misssouri River the Cretaceous beds in Colorado and New Mexico may be separated into the five groups without much difficulty. No. 3is represented by a thin bed of impure gray limestone and thin calcareous shale, with Ostrea congesta and a species of Inoceramus. The fossils are about the same as those occurring on the Missouri, but the rocks have little of the chalky texture, as observed in the Northwest and in Kansas. Nos. 2 and 4 are black shaly clays, and do not differ materially from the same groups occurring in other localities to the northward. No. 5 contains a great abundance of well-marked Cre- taceous fossils, many of the species identical with those found on the Missouri River. This group passes up into the Lignite strata, appar- ently without any marked unconformability. In passing upward in number 5, one by one the mollusca of purely marine character disappear until only some varieties of oysters remain with the plants peculiar to the Lignitic group. I may say here that it is quite possible that a more thorough examination of the strata intermediate between those with well-defined Cretaceous fossils and the Lignitic beds would show at least an uncomformability of sequence. In the Laramie Plains there is a group holding this intermediate position of several hundred feet in thickness, which I have called beds of passage. There is an interesting fact which may be stated just here, that there are no important flexures in the sedimentary group, whaiever there may have been in the Metamorphic rocks, but the difference in the inclina- tion of the former is very great at different localities. Sometimes the . uplifted zone is ten to fifteen miles in width and composed of a great " HAYDEN.) EOLOGY—COLORADO RANGE. Lg number of ridges, which are called in the country “ Hogbacks.” Some- times the inclination of these ridges from the granite nucleus outward to the plains is not more than from 10° to 259, gradually diminishing until the Lignitic strata assume an entirely horizontal position, so far as can be detected by the-eye. Again, the entire group of strata will be crowded into a space of a mile or less, and stand at a nearly or quite a svertical position, but in suddenly passing from a very highly inclined position to an apparently horizontal one on the plains, we can see that however much the Metamorphic rocks which form the nucleus or body _of the great mountain-ranges may have been folded by the shrinking of the crust, the sedimentary beds have been simply lifted up in a nearly or quite vertical manner. I have often stated in previous reports the belief, founded on most satisfactory evidence, that the sedimentary strata formerly extended uninterruptedly across the area now occupied by the Metamorphic mass of the mountain-ranges; that on the east and west slopes can be found the broken portions inclining in opposite direc- tions, but showing most clearly that the intervening portions had been worn away ia the process of upheaval. The sections across the range will illustrate this statement most clearly. So far as can be seen at the present time the process of upheaval has been very slow, long continued, and uniform in its action. In many instances the sedimentary group seems to have resisted the central force, and thus the strata were broken off, and the edges turned up very abruptly over a very narrow belt or zone, as at Golden City, and many other localities south of that point. Again, the uplift seems to have influenced the strata for a long distance from the Metamorphic nucleus into the plains, as at Cache a4 la Poudre, where the inclination of the beds is nowhere very great, and gradually diminishes eastward until they become quite horizontal ten to twenty miles from the axis of power. In many instances the force from below seems to have acted so nearly vertically that only the Lignitic and per- haps a portion of the Cretaceous strata are exposed on the flanks of the nucleus, and thus beds are broken off so abruptly that the detached por- tions are thrown past a vertical and incline away from the mountain mass; in other words, the great Metamorphic mass that forms the nucleus of a range has been pushed up so directly vertical that the operation cid not materially disturb the sedimentary group except immediately around the flanks. This phenomenon is not uncommon over the eastern portion of the Rocky Mountain district. As the details of the geology of the different districts are more fully worked out these points will appear more clearly to the mind of the reader. It will be seen that the geological structure of the Rocky Mountains is comparatively simple in its general outlines, but that in its details it is remarkably complicated. In the third annual report of the survey, season of 1869, I noted an interesting feature in the structure of the mountain-ranges along the eastern flanks, from Cheyenne to Santa Fé. I directed attention to the curious anticlinal ridges that seemed to extend down from the main range aud die out inthe plains. Thus the great range or mountain mass that fronts the plains from our north line to Mexico is made up of a vast number of smaller ranges grouped together; and while the great mass, as shown on our maps, has an aggregate trend about northwest and southeast, the front range from Laramie Peak to Santa Fé seems to strike about north and south. If we examine the eastern flanks of the range we shall find, from point to point, smaller ranges or spurs extend- ing down from the main mass toward the plains, with a trend about northwest and southeast, and soon dying out, leaving between the end of the spur or minor range and the main mass a broad open valley, which forms the sources of the more important streams. Most excellent illus- \ 20 GEOLOGICAL SURVEY OF THE TERRITORIES. trations of this structure are seen where the Big Thompson and Saint Vrain’s Creeks emerge into the plains. Great notches are there formed from point to point along the east front of the mountains, from which some of the most important streams, or their branches, emerge into the plains. Cache 41a Poudre, Big Thompson, Saint Vrain, Fountain Creek at Colorado Springs, and the Arkansas River near Cafion City, are excellent examples. This feature in mountain structure is shown in a still more emphatic manner farther to the northward, where the front group flexes to the northwest, leaving, however, somewhat separated the Black Hills of Dakota, the Big Horn range, and the. numerous smnaller ranges on the Upper Missouri. These ranges, large and small, are all linked together at some point more or less apparent by anticli- nals. By examining a general map of the Western Territories it will be seen that the Black Hills of Dakota are connected with the front range near Fort Laramie, and that the Big Horn Mountains are united farther north at Red Buttes by a low anticlinal that crosses the interval, re- vealing no rocks older than the Cretaceous. These lines of connection are best shown by colors on a geological map. The illustration (section 1) will show quite clearly the dying out in the plains of one of these spurs or ridges. Itis also a fine example of an anticlinal. Big Thompson Creek cuts its channel through the south end. The portion thus separated forms a conical hill about 120 feet high above the south base, or about 200 feet above the valley of the Big Thompson. The Upper Cretaceous beds pass off in low semicir- cular ridges southeast. The main mass of the hill is triangular in shape, and is composed of the rocks, of various textures, which make up the Dakota group. The character of the group is well shown in this local- ity. The pudding-stones, made up of small rounded pebbles, seldom more than one-fourth of an inch in diameter, smoothly polished, sand- stones and quartzites of almost every texture, with slicken on a marked scale, and with the surface lined with white amorphous quartz. The stream, which separates the triangular end of the anticiinal, cuts directly through the ridge at right angics, and exposes in the section the red beds very distinetly. The trend of the ridges is about 20° west of north, with the uplifted ridges on either side inclining 16° to 209 east and northeast; on the west side of the ridge, No. 1 presents an almost vertical wall for a mile or more, rising from a few feet to 100 or 150 feet in height, resembling the broken wall surrounding some old city. This will always be pointed out to the traveler as one of the curiosities of the region, aside from its geological interest. Just inside is the rather thin group of Jurassic beds; in the aggregate about 200 feet in thickness, made up of irregular thin layers of indurated arena- ceous clay and sandstone, with two or three beds of limestone. Not a trace of a fossil could be found, although a hundred and fifty miles north well-marked Jurassic fossils are abundant; and twenty-five miles north they occur to some extent. The thinning out of the Jurassic group in its southward extension is well marked, unless we include the red beds among rocks of that age. Below the well-marked Jurassic group the red sandstone appears, forming several small, rather low, ridges, with thin beds of bluish-gray limestone, quite impure, but used for burning into lime. Here and there, in close proximity to these lime- stone layers, we have irregular deposits of gypsum. It is only in the red group that these gypsum-deposits are sufficiently developed for economical use. Gypsum in some form occurs in all the formations above the Carboniferous; but in the Cretaceous and Tertiary forma- tions it is found mostly in the form of selenite. The origin of the gyp- ~ sum is so wel) known that I will not refer to it in this place. It may be nd of BF @ Section I. ca Biy Thoapson Cr. b Little Thompson ec End of L¥ antehnal spur d End of 29 ardel. Spr: eLind of 3? ante. spr: 7 Jt. Vratns Cr. Southern Find of Anticlinal on Big Thompson Creek. Section on St.Vr ains Cr. a ard 6 Oral Openings tw Puffs . e ltidge of Vo. 7. Dakotah Croup. @ Syrettreal Valley. e Red Sandstones, (riassic. £ Granttes. Satine , a penn iter Se Ley HAYDEN. | GEOLOGY—COLORADO RANGE. Dili stated, however, that the absence or presence of large deposits of gyp- sum seems in no way to afiect the beds of limestone, although the gyp- sum occurs in greater or less quantities all along the eastern sides of the mountains wherever the group of red beds is exposed. There is a very plain thinning out of the calcareous rocks as we proceed south- ward. North of the railroad the Carboniferous limestones are quite thick in some places; near Fort Fetterman they reach a thickness of 1,000 to 1,500 feet, while south of the railroad the aggregate of the limestone layers would not amount to more than 25 to 50 feet. The beds or deposits of gypsum are much more extensive to the northward, around the Black Hills, reaching a thickness of 40 to 60 feet, amor- phous, and of a snowy whiteness. The central portion of this anticlinal is a rather low grassy valley, with one or two low ridges rising 2 to 4 feet above the surface, the brick-red edges of the softer intervening strata outcropping here and there where the reck is rounded. The intervening valleys between the ridges are of various widths, depending upon the thickness of the indu- rated calcareous sandstones. From their irregularity in weathering there must be a very great variability in the texture of these brick-red sandstones from point to point at not very great intervals. This differ- ence is shown all along the base of the mountains. Sometimes the ridges are very high and the upturned portions form a belt of consider- able width, composed of quite compact sandstones and quartzites; then, within the space of a few miles, the greater portion of the group will appear to be made up of indurated sands, which yield readily to atmos- pheric agents. The irregularity in the wearing down of these ridges is undoubtedly due in part to other causes, which will be discussed in an- other portion of this report. In the vailey between the two sides of the anticlinal are several lime-kilns, and the limestone is taken from a bed 2 feet in thickness, rising above the surface a few feet and standing nearly vertical. On either side of the limestone the arenaceous lime- stone and sandstone are very cellular, looking much like a spring de- posit of tufa. It is certainly very gypsiferous all the way through. There are two or three of these thin beds of limestone about the middle of the red group, but no fossils have ever been detected in them. This anticlinal valley, although so short, is very beautiful. At its upper end it is about half a mile wide, tapering to a point on the southside of the Big Thompson, so that it is about three miles in length. The west por- tion of this anticlinal forms also the east side of the beautiful synclinal valley, through a portion of which the stream flows. The eroding agents have smoothed out this concave synelinal valley, which is almost entirely grassed over, so that no formations can be seen newer than No. 1. The quartzite wall on the east side, which stands 80° at Jeast, must have been broken off, so that the under- ground portions cannot be very deep, but pass beneath the valley and rise up on the opposite side, inclining at a very moderate angle. This peculiar arrangement of the ridges produces a very curious drainage tor the Big Thompson and its branches. On the south side of the val- ley of the Big Thompson the long, low, Cretaceous ridges can be seen from a high point extending across the surface to the north, but stop- ping abruptly at the creek, while the synclinal interval gradually closes up to the northwest, in the valley of the East Fork. South of the main stream, and on the west side of the synclinal valley, the No. 1 ridge is very prominent, and runs up to Big Thompson close above the Red Stone Creek, as seen on the maps. Between the end of the anticlinal south of Big Thompson, and the same ridge as it rises on 2, GEOLOGICAL SURVEY OF THE TERRITORIES. the south side of the same stream, the distance across the synelinal valley is about three miles. As we pass up the axis of this triangular anticlinal we find within it an open triangle; or, in other words, high ridges of sandstone incline east, west, and south from the nucleus of mica schists. The sandstones forming the ridges of this inner triangle are much more compact in texture, varying from a sandstone to quartz- ite and pudding-stone. The pebbly portions are scattered irregularly through the mass, showing everywhere that the sediments were depos- ited in shallow and disturbed waters. Indeed, it is seldom that the red groups give any evidence of long periods of quiet deposition. Passing over the ridges of sandstone, which rise above the anticlinal valley about 200 feet, we ascend a ridge of black mica-schist, which, on account of its peculiar texture, I have called ‘“bird’s-eye schist.” The surface of these slate-like shales is covered with circular pits, while the mass of the rock has a wavy texture, the whole reminding one at once of a kind of timber common in our Northern States, known as “ bird’s- eye maple.” The south end of the schist-ridge rises 1,100 feet above the valley of the Big Thompson, at the old stage-road. The second ridge, still farther north, is 1,450 feet, while the highest part of the spur is over 2,000 feet. The highest point is not over 8,000 feet above sea- level. It will be seen at a glance that this ridge or tangential spur, as it might be called, isa remarkable feature in Rocky Mountain struc- ture; that the internal forces should strike off at a tangent, as it were, elevate a branch ridge from the main chain, and so suddenly, and in many cases abruptly, die out in the plain, is difficult to compre- hend. We shall endeavor to present the facts from time to time with as much detail as possible, leaving the primary causes to become more clearly known as we can accumulate illustrations. The synclinal on the southwest side of the spur continues up until the spur joins on to the main nucleus of granite. The ridges forming the east side of the anti- clinal extend continuously along the east base of the mountains to Cache & la Poudre, while the west side is cut off by the schist-ridge. The synclinal is closed up in a sort of pocket or cul de sac, forming the drainage of the North Fork or Red Stone Creek. Thered beds lie close up against the granites, while the branches of the Little Fork have cut their way through the ridges, as shown in the small chart. The schists in the spur extend down as a sort of tongue between the uplifted ridges of sedimentary rocks on either side. The schists all incline west or south of west 60° to 80°. The strike of the schist-ridge or spur is about northwest and southeast. The ‘‘hogback” ridges on the east side, ex- tending along the base of the mountains to Cache a la Poudre, are quite regular, and incline 20° to 25°, There is usually an interval or valley between the schists and the first ridge, as shown on the surface, though beneath the valley the red sands and sandstones jut up against the up- turned edges of the schists. About five miles to the northward, on the east flank of the mountains, a group of massive red feldspathic granites rise up beneath the schists, and the surface has the appearance of a great morai- nal deposit, so rounded are the detached masses of granite. These worn blocks were scattered over the sedimentary as well as the Metamorphic rocks and show marked signs of former glacial action. Such examples may be found everywhere along the mountain sides. The subject, how- ever, may be more fully discussed in another place. At this point rem- nants of the lower sandstones lie high up on the granites, inclining 60° to 80° southwest, while the upper sandstones dip nearly 20° east. The sandstones, as they lie in contact with the granites, filling up the irreg- ularities of the surface, are composed of a loose aggregate of quartz, HAYDEN. GEOLOGY—COLORADO RANGE. 23 pebbles, and other Metamorphic rocks, with a coarse quartzitic sand asa cement. There were many deep depressions, which are filled up in a remarkable manner. These tongues or ridges of granite extend down from the main range in many places, but seldom so far as to break the regularity of the upheaved sedimentary ridges. Between Big Thompson and Cache & la Poudre there are quite wide grassy intervals between the ridges, which produce excellent grazing for cattle. These ridges are well defined; there are usually about two principal ones of the red group, and one very high and prominent ridge, composed of No. 1, underlaid probably with the Jurassic group. The Dakota group ridge is immensely developed all the way to Cache 4la Poudre. On the inside of the ridge vast blocks of quartzite and pudding-stone, 20 feet cube, have fallen down into the valley or lie thickly scattered on the sides of the ridge. At Spring Canon, nine miles north of Big Thompson Station, there is a splendid section of the entire sedimentary group. The little streams seem to have cut their channels direct from the mountain-sides through the series of ridges at right angles. The Dakota group is at least 250 feet thick, and is composed of beds of fine- grained sandstone or quartzites, which are much used for building pur- poses. So much has already been written in regard to the Cretaceous group, aS shown south of the railroad, that I do not know that I can add anything new in this chapter. The very minute and accurate sec- tions of Mr. Marvine will make the succession of the beds, as well as the relative thickness from point to point, perfectly clear. Between Cache a la Poudre and Big Thompson, the ridge composed of No. 1, or the Dakota group, is most conspicuous, forming a peculiarly sym- metrical roof. This ridge is higher and more uniform than any of the others on either side of it, due probably to the fact that the texture of the rocks of the Dakota group is so much more compact and resists the wear of the atmosphere more effectually. The slope of the roof is about 20°, and although much of the surface is bare, the upper portion is covered with scattering cedars of a stunted growth. At irregular but short intervals inverted conical notches occur, produced by the little streams, which have worn their way, to a greater or less depth, directly through the ridge. The more important streams have cut deep channels from the mountains through into the open plains, but in the intervals are numerous depressions, like those shown in the illustrations, that indicate the erosion of temporary streams, thus giving a wavy outline to the outcropping edge of the ridge. We may say here in this connection that the Dakota group is one of the most widely-distributed forma- tions in the West. To attempt to describe the variations in structure from point to point would be an almost endless task, and yet, when care- fully studied in one locality by the geologist he never fails to detect its presence at other points where it exists, if exposed. All over the great middle belt of the West, so far as I have observed it, between the paral- els 479 and 34° and the meridians 97° and 114°, it maintains enough of its peculiar lithological character to be readily detected, and thus, although in most instances destitute of, or containing very imperfect organic remains, it forms a permanent basement-floor for the great Cre- taceous formation of the West, as well as a most important datwm line for determining the age of the rocks above and below. The numerous species of plants, with a few invertebrate fossils, which have been found on the Missouri River and in Nebraska and Kansas, have fixed the age of the group, so that we believe it passes beneath all the more modern beds from their points of appearance at the Kast to their exposure along the flanks of the mountains.. The eastern portions of this group are 24. GEOLOGICAL SURVEY OF THE TERRITORIES. composed of a considerable thickness of dark iron-rust sandstone, in which the plants are found for the most part. In the West this sand- stone is not found in so marked a degree. Volume 7 of the quarto series, by Professor Lesquereux, contains 30 plates entirely devoted to the plantsof this group. The physical history of this group would be one of great interest if we had all the details, forming, as it does, the line of separation between two of the most important of the Mesozoic ages. Indeed I have sometimes regarded it as a sort of transition group be- tween the true Jurassic and Cretaceous series. The exact line of separa- tion between the Cretaceous and Jurassic I have never seen, unlessit be the lowest layer of sandstone. The beds of sandstones, quartzites, &e., form the characteristic feature of the group, but the beds are usually separated by perhaps layers of indurated clay or shale, which are of variable thickness. Itis also probable that the Dakota group passes gradually into the Jurassic through softer strata, for the sand- stones are indurated with lower arenaceous clays. I hoid the position that the sequence of all formations is to be sought for in all places; that while breaks not unfrequently occur, the normal condition is the entire absence of any line of demarkation, so that with the closest scrutiny the geologist cannot tell where one formation ends and another begins. Variability in texture and composition is regarded as indicative of transition from one age to another, and this peculiarity is so persistent in the Dakota group wherever it is known that I have been disposed to regard it as a transition series, although the organic remains do not fix it positively at the base of the Cretaceous. Itis even possible that an uncon- formability of sequence will yet be found. All through the group the layers give unmistakable evidence of the shallowness of the waters of the ocean during the deposition of the sediments. It seems somewhat sin- gular that so widely-distributed sea-deposited rocks should exhibit such uniform proof of shallow-water deposition. The rocks are usually in rather thin layers, with very irregular lamine of deposition ; the sedi- ments vary from a fine to a coarse sand or gravel, also from a fine pudding-stone, made up of an aggregate of smoothly-worn pebbles from the size of a pea to an inch or more in diameter, sometimes so closely cemented together that the fracture of the mass is lable to pass through the pebble. In somewhat rare instances this pudding-stone becomes a coarse conglomerate. The average thickness may be stated at 200 feet, but vibrates between 100 and 250 feet. Between the sand- stones are perhaps partings of indurated arenaceous clay, and about the middle of the group is a seam of impure Lignitic clay, which has often been prospected tor coal. Along the Missouri River, in the vicin- ity of Sioux City, lowa, and in Southern Nebraska and Kansas, this last is 2 to 4 feet in thickness, and has been wrought to some extent for fuel, but with poor success. Along the margins of the mountain- ranges there is no certainty of its appearance at all; still it crops out from point to point from the north line to Mexico. The entire group of sandstones. show that shallow water and land were near, or at least areas where vegetation could grow, for all through the rock are fragments of leaves, stems or sticks, and sometimes coal. Many ot the beds are sort of mud-sandstones, of a drab-brown, from the «bun- dance of indistinct fragments of vegetable matter. Sometimes, in the more compact homogeneous layers, well-defined leaves are found, usually of a deciduous type. Leaves were found in these rocks, near Denver, along the line of the Union Pacific Railroad to Ogden, and in the Elk Mountains. The sandstones pass up into brown arenaceous clays, with rather thin layers of mud-sandstones, full of mud-markings, which re- MiSoeNe: GEOLOGY—-COLORADO RANGE, 25 semble casts of sea-weeds with fragments of vegetable matter. Then comes black shaly indurated clay, which indicates quiet deposition in moderately deep waters, at least. This is what we have usually denom- inated No. 2, or the Fort Benton group, and sometimes attains a thick- ness of 200 to 600 feet, quite homogeneous in character. There is now and then a calcareous layer which is charged with fossils, as Inocera- mus, Ostrea congesta, and other well-marked Cretaceous forms. Above the Dakota group the Cretaceous rocks have very little influence on the scenery further than that the dark saline clays of No. 2 and No. 4 give the appearance of an arid sterility to the surface, Nos. 2, 3, 4, and 5 are usually so soft and yield so readily to the atmospheric agents that, where the mountain-streams emerge from the Dakota group, they flow out into the plains. In some instances they have escaped erosion and occur in a series of low ridges which pass off eastward into the plains like the waves of the sea, This is well shown north of Cache & la Poudre, where the Lignitic group is involved in the uplift and the belt of uplifted ridges is several miles in width, but inclining at very small angles. No. 3 Cretaceous is not well defined, yet it has a representation in the yellow and gray limestones and shales or slates. The chalky limestones are often full of the characteristic fossils of No. 3. Along the base of the mountains in Colorado, No. 3 forms rather low, rounded ridges, grass-covered, and not easily studied except where the mountain- streams have cut deep channels directly through them. We can thus trace the continuity complete, so that we find the passage from No. 2 to No. 3, and from No. 3 to No. 4, then to No. 5, as gradual as if they were all united in one group without any possible liné of separation. No. 8 varies from 50 to 100 feet in thickness, so far as can be seen, yet the difference in thickness at different points may depend somewhat on the clearness or obscurity of the exposure. That all these groups vary in thickness at different localities would be expected, but I doubt very much whether from any exposures along the flanks of the mountains these variations can be determined with any degree of certainty. Nos. 2 and 4, made up as they are of indurated shaly clays, yield more readily to the eroding agents, and No. 3 rises up between them in a low rounded ridge from a few feet to 50 or 100 feet in height. No. 2 usually underlies the concave parallel valley or interval between the high sharp ridge composed of No. 1 and the low eroded ridge of No. 3. No. 4 forms the more slightly coneave de- pression petween Nos. 3 and 5. ‘This series of parallel valleys between the ridges, with a general trend north and south, is a feature peculiar to the flanks of the mountain-ranges, and is best shown, on account of the vast continuous extent, on the eastern side. The intervals are usually softer materials, and have been worn out more or less smoothly by the elements and then grassed over, so that some of the finest farming and grazing lands in the Rocky Mountain’ districts are found here. These valleys are so inclosed that they are protected from the winds and storms, and in consequence old settlers are working their way up from the plains to the immediate base of the mountains in consider- able numbers. As a range for stock these valleys are admirable. The pictorial sections will illustrate what I mean by these parallel valleys. _ The mountain-streams cut through them atright angles. I have already, ~ in the annual report for 1870, called attention to the wide parallel val- leys north of the railroad between the older rocks and the modern Tertiary or lake-beds. In general appearance No. 4 resembles No. 2, yet the latter is more plastic and of a darker color thanthe former. No. 4 is an indurated clay, some- 26 GEOLOGICAL SURVEY OF THE TERRITORIES. times becoming a sort of slaty shale. South of the railroad it contains very few fossils. It is not a thick bed, rarely exceeding 100 feet, and gradually passes up into the yellow arenaceous clays of No.5. No. 4 usually underlies one of the parallel valleys, and can only be studied to advantage when astream flowing down from the mountains into the plains cuts a channel through it. In these localities the gradual litho- logical changes may be observed. A low ridge is formed by the beds of transition between Nos. 4 and 5, which is sometimes so regular and con- tinuous that it looks like the ruins of an old wall. The shale gradually becomes dull brown, indurated clays alternating with thin layers of mud- sandstone, and finally rising up to rather thick sandstones of various degrees of brown and rusty-yellow color. In some localities the fossils are quite abundant, as in the valley of Cache a.la Poudre, near Greeley, and in the valley of Big Thompson, west of the Denver Pacific Railroad. Here are found rounded concretionary masses, like huge cannon-balls, resembling those of the same formation on the Cannon-ball River, which empties into the Missouri River from the Hast, far up in Dakota Territory. These singular concretions contain quantities of well-marked Cretaceous fossils, Ammonites, Baculites, Inoceramus, &e., &c. This eroup of calcareous sandstones, which reaches a thickness of 100 to 200 feet in this region, I have regarded as the upper portion of the true Cretaceous groups. These pass gradually up into the Lignitic formation, about the age of which there is some discussion among paleontologists. North of Saint Vrain’s Fork, the Lignitic group, as well as the upper por- tion of the Cretaceous, is seldom lifted up at a high angle, usually 3° to 15°, the angle of inclination becoming less and less as the ridges die out eastward in the plains. The lower portion of the Lignitic group shows the influence of the forces that elevated the mountains, but soon they become nearly or quite horizontal, and far east of the Cache a la Poudre pass under the White River deposits. The latter thin out in their south- ‘ern extension, so that they are not unfrequently worn down to the un- derlying Lignitic beds. About twenty miles south of Cheyenne there is a bed of coal 5 to 6 feet, in thickness, and above it is a bed of oyster- shells 4 feet in thickness. Many of them are quite perfect, but they are mostly fragmentary and worn, as if they had dritted into this locality. In the lower portion of the Lignitic group it is very common to meet with seams or beds of Ostrea, of various species. This species resembles very closely a form holding about the same position on the Upper Mis- souri, in the valley of Grand River, known as Ostrea subtrigonalis. In both localities it oecursin the lower portion of the Lignitic group, and in the ascent gives place to purely fresh-water types. At the Mar- . shall coal-mines, south of Boulder City, I have collected small forms of Ostrea, in strata above the most important beds of coal, and also along the Un on Pacific Railroad, at Point of Rocks, Black Buttes, and other sta- tions, where the coal-beds are very numerous and their order of succes- sion well shown. The various forms of the genus Ostrea are abundant, passing up through several hundred feet of the coal group. It is not my purpose to enter into a discussion of the age of these beds in this connection. In a previous report I stated that the relations of the well-defined Cretaceous group with the Lignitic forms one of the - most impertant problems in Western geology, and that no effort would be spared to accumulate all the evidence bearing on the question possi- ble. I believe that the area for the solution of the question lies in the Laramie plains, and westward toward Salt Lake. There in the agere- gate are 10,000 to 12,000 feet of Cretaceous and Lignitie strata. Contigu- ous districts may aid in throwing light on the subject, but with all that Sata GEOLOGY—COLORADO RANGE. Dat has already been done this region presents one of the most attractive fields of geological research on this continent. The relations of the fresh-water lake-deposits with the Lignitic is another interesting sub- ject for investigation, and will probably be settled in connection with the former. So far as we have the more important problem considered we find the evidence from the vegetable remains wholly in favor of the Tertiary age of the coal group. “The vertebrate remains, according to Professor Cope, place them with the Cretaceous group, while the proof from invertebrate fossils is not strong in any direction, although, perhaps, lean- ing toward the Tertiary. We must admit, however, that the lower coal- beds are of Cretaceous age so far as the evidence goes. For instance, the Coalville and Bear River beds are most probably Cretaceous, inas- much as many undoubted Cretaceous types are found in strata above the coal. J admitted this evidence as far back as 1869 in a paper read before the American Philosophical Society. I am more convinced that farther south, in New Mexico, Arizona, and Utah, there are coal-beds of undoubted Cretaceous age. The main question, then, is this: Ave the vertebrate paleontologists, Cope and Marsh, justified in regarding the entire Lignitic group as Cretaceous from the evidence furnished by the vertebrate re- mains? During the progress of the survey this subject will be discussed from time to time with all the light that can be gathered from every quarter. We have in the preceding pages endeavored to describe some- what in detail the sedimentary recks as exposed in the vicinity of the Big Thompson Creek, and either north or south of this point they do not differ materially in their general character. We may now move rapidly southward along the base of the mountaifis, noting here and there some peculiar features of interest which may have escaped attention in former explorations. About five miles south of the Big Thompson a shaft has been sunk to some depth, apparently in search, of coal. It is just over the quartzite No. 1, and shows very clearly the relations of No. 2 to No. 1. ‘The shales incline about 15°. In some thin mud-limestones Ostrea and IJnoceramus were observed in great numbers, mostly in fragments. A considerabie quantity of silicified wood was found here also. There is here an im- portant ridge which seems to be made up of a fragment of No. 1 ora stratum of No. 2—most probably the latter. 1t is composed of a gray mua- sandstone about 15 or 20 feet thick, and in many places filled with veg- etable impressions which must have been originally tormed by sea-weeds. They are not distinct enough to determine, but have the forms of black irregular stems, and from the mass of these markings the sea-weeds must have grown here with great Juxuriance. It is not uncommon for a se- ries of the border layers, as alternate beds of mud-sandstone or quartz- ites, with shales or clays, to occur in many of the beds. These layers disappear again in shales. About two miles north of the Little Thomp- son we find the quartzites standing nearly vertical in a sort of frag- mentary wall. This was accounted for by another of these spurs from which the greater portion of the Cretaceous beds had been worn away, leaving a sort of semi-quaquaversal, (section 2,) Nos. 2, 3, and 4 in- clining from a convex or dome-shaped ridge or puff (?) of No. 1. This is certainly a very interesting example of the connection of the quartz- itesof No. 1 in what might be called an anticlinal. The trend of this puff (d) isabout 30° west of north. On the west side of the puff there is an interval of half a mile, a synclinal valley extending down from the base of the mountains, underlaid with Nos. 2, 3, and 4, which originally ex- tended over the puff. About two miles south of Little Thompson there is another of these convex ridges (d) which shows the en échelon 25 GEOLOGICAL SURVEY OF THE TERRITORIES. tendency of the mountain-ranges. It extends out tangentially several miles from the base of the main range into the plains between Little . Thompson and the north branch of Saint Vrain’s Creek. Just as the Saint Vrain emerges from the Hogbacks in the plains, the valley ex- pands to a width of at least five miles, (¢,) so that there is only this main ridge or spur between the drainage of the Little Thompson and Saint Vrain’s Creek. This ridge is also partially domed over, although a portion of the Upper Cretaceous beds incline away from the ridge on all sides. Ontheeastsidean oval mass has been removed through the quartz- ites of No. 1 and the Jurassic group, just exposing the red beds in the bot- tom of the depression. The quartzites stand up nearly vertical on the east side, forming a semicircular wall, while on the west side the summit rises 830 feet above the valley of Saint Vrain, with a dip of only 20° or 30°, The layers of rocks are quite massive, 4 to 6 feet thick, composed of a beautiful pudding-stone, the pebbles rounded and as smooth as glass. There is here at least 10 or 15 feet of solid pudding-stone, and the peb- bles all through it have the same elegant smoothness and are sometimes an inch or two in diameter, but usually smaller. The depression as well as the sides of the ridge are covered with huge cubical masses that have fallen down. The last two smaller spurs do not appear to have inter- rupted to any extent the trend of the ridges. On the north side of the ‘Little Thompson and inside of the uplifted ridges the short rounded Schist-spur is distinctly seen trending northwestand southeast, which has produced the puff. The oval opening (d) in the puff is about half a mile wide and a mile long, produced by erosion. ‘To one traveling between the Hogback ridges and the granites these tangential movements of the internal forces do not seem to have disturbed the symmetry of the prin- cipal series of ridges. The Little Thompson in passing through the main ridges cuts them at right angles, and on the north side a fine, reg- ular vertical section is shown, with the beds all in their normal position, while on the south side the same beds incline toward the north from the ridge or puff that extends down into the plains, (well shown in sec- tions 2 and 3.) The Little Thompson, after emerging from the sand- stone ridges, cuts a deep channel through the calcareous shales of No. 3. The bed is here 200 to 300 feet in thickness. These unusual develop- ments of a group show the difficulty of obtaining the exact thickness of these uplifted groups of strata at different points with any degree of accuracy. We may call this spur an oblong quaquaversal, for the beds incline at greater or less angles from both sides, and come around the end, forming quite distinct semicircles. Nos. 1,2, and 3 form distinct ridges from the end of the spur, and the plains below show clearly that they are underlaid by the softer materials of the Upper Cretaceous. On the south side of the spur there is a triangular-shaped valley, through which the north branch of the Saint Vrain flows from the base of the mountains. The upper part of this triangle is a synclinal, as is so well shown in the illustration. South of Saint Vrain’s Creek the ridges begin to close up rapidly, so that at Boulder Creek they form a narrow belt. Two or three fragmentary ridges of Lignitic sandstone rise above the surface 20 or 30 feet, not over three miles from the foot of the mountains, and the strike would carry them close up against the very base near Boulder Creek. The coal-strata continue to approach nearer and nearer, until between Boulder and Clear Creeks they form a portion of the foot-hills. The terraces along the base of the mountain are very remarkable, and will be noticed more fully in another place. As they are composed of superficial deposits the ridges pass under them at times, and are hidden Dyke at Valmont Grud View 5 AAMT LT) Ae Fema del Section of Dyke eae GEOLOGY—COLORADO RANGE, 29 from view. We will allude to these terraces again, under the head of glacial effects, which are very conspicuous everywhere, and nowhere more so than in the valley cf the Boulder. Near Boulder City the ridges hug the base of the mountain closely, while between North and South Boulders they are worn away, mostly exposing the granites. The terraces, as well as the lower valleys, are literally paved with water-worn bowlders of all sizes. The origin of the agencies which have produced these efiects is evident frem the fact that as we recede from the mountain the bowlders diminish in size as well as quantity, until far down in the plains they almost entirely disappear. There is no evidence that the superficial deposits are of remoter origin than the immediate mountain-side. At Valmont, in the Boulder Valley, about five miles below Boulder City, there is a singular dike of augitic dolerite, which rises up nearly through the hor- izontal Lignitie strata ikea wall. Its strike is about south 67° west. It runs directly up the valley and parallel with it at right angles to the mountain-ranges, and evidently had a much greater extent than at present. It has been uncovered for the most part, and perhaps entirely, by the wearing out of the valley of the Boulder. Originally the igneous material must have been forced up vertically, filling the fissure like a mold; and while the soft yielding sandstones and clays that surrounded it were easily swept away by the eroding agencies, this dike, by the great hardness of the rock, has resisted so that it remains like ver- tical walls. The highest portion is just at Valmont, and is 300 feet above the base, while at either end in a line with the main mass is a raised ridge covered with the fragments of dolerite. At the top it is 30 feet wide, but expands to 50 feet or more at the base, while farther down, where the dike is much broken, it appears to be 150 feet. It undoubtedly varies in width from 50 to 150 feet. The south side of the dike is washed by the Boulder, and is nearly vertical and loose, while the north side is covered with the broken fragments and the sedimentary beds jut up against it without any evidence of much disturbance. From the sum- mit of the highest point the view up and down the valley is very fine, and nowhere in Colorado can be gathered within a single scope of the vision so abundant and so great a variety of the resources of Colorado. The railroads are in operation here, and the broad valley from the mountains down for thirty miles or more is covered with fields of grain ‘and other products of the farm. On the south side in the high hills numerous openings for coal may be seen, and between Boulder Valley and Clear Creek the bulk of the coal of Colorado exists. The valley near the base of the mountains is full fifteen miles in width, but graduaily narrows as the long benches that extend down on either side approach each other, and the little branches all unite in one stream. So far as we can determine from the surface, the dike extends about four miles in a direct line, and from the west end to the east end the strike is about north 30° east. The Lignitic beds incline down the stream, or about west 1° to 3°. About half a mile north of the dike, on the north branch of the Big Boulder, there is a fine exposure of the yellow-gray sandstone, apparently horizontal. Indeed, wherever any of the underlying Sedimentary rocks are exposed, they do not seem to have been disturbed by the forcing up of the igneous matter, and we may therefore conclude that it merely filled an original fissure as a mold. I will now pass hastily over the remaining portion of the country to Colorado Springs, presuming that the reader will find a general view of this region, with a pretty clear exposition of the great features of the 30 GEOLOGICAL SURVEY OF THE TERRITORIES. geological structure, in my report for 1869, but calling attention to the more detailed work of Mr. Marvine and Doctor Peale. I may say here that soon after leaving the base of the mountains we have what are usually called the plains, and the slope is generally to the eastward, becom- ing less and less to the Mississippi River. Ten miles from the foot-hills the general elevation is from 5,000 to 6,000 feet above the sea ; the surface is rolling, and in traveling from north to south we gradually rise to the summit of one water-divide and descend into the valley of some stream which flows from the mountains. These streams are usually, on an average, about ten miles apart, and from one margin of descent to the opposite side it is from five to eight miles. These valleys have been worn out slowly by causes which will be noted in another portion of this chapter. In a former part of this chapter I described in detail the series of sedimentary beds from the granite nucleus of the mountains eastward. into the plains. From Cache ala Poudre tar southward to the Arkansas the plains are underlaid by some portion of the Lignitiec group. Thesu- perficial deposits are so extensive and the exposures of the underlying beds so rare that it will always be difficult to werk out the succession of the beds in detail. It is most probable that Denver is underlaid by the lower portions of the group, and that the divide far southward between the waters of the Platte and Arkansas is composed of upper beds of this group. The aggregate thickness of the entire group, as seen in Colo- rado, cannot be less than from 3,000 to 5,000 feet. Ona geological map attached to my final report of Nebraska I represented the fresh-water lake deposits as overlapping the Lignitic and extending far southward toward the Arkansas. It is probable that some portion of that area is occupied by the Lignitic group alone. That the Lake or White River group covered a larger area southward along the base of the mountains is most probable, but that has been worn away so that the present area occupied by them would extend around to the southeast, much as shown on the map. Iam not positively certain that they extend south of the line of the Kansas Pacific Railroad. We know, however, that they cover a large area south of the Union Pacific Railroad. ast of Denver the Lig- nitic beds must extend two hundred miles without interruption. It is possible, also, that somewhere in this great area basins occupied by more modern Tertiary deposits may yet be found. It is probable that the Car- boniterous group does not occur continuously, as colored on the map, from the line of the Union Pacific Railroad to Colorado Springs. Near the sources of Fountain Creek both the Carboniferous and Silurian beds appear, and then southward, interrupted here and there, the former group occurs along the flanks of the mountains. The more carefully- prepared maps, which will be made hereafter by the survey, will correct all local details, though in a general way this map was very correct. I have already alluded to the fact that the belt of uplifted sedimentary ridges became narrower at the Big Boulder. Between the Big Boulder and Clear Creek all the strata were lifted up ata high angle. Even the Lignitic strata are close to the granites, and stand at high angles, varying from 40° to 70°. South of Clear Creek the belt is not wide, but it expands somewhat wider now and then, but south of Platte Cation hugs the mountains even more closely, the inner or lower strata lying high on the sides of the foot-hills. Nowhere along this belt, from Big Boulder to Plum Creek, do we see any traces of undoubted Carbonif- erous beds. The lowest strata exposed next to the granites vary some- what in color and texture; the prevailing color is brick-red, or reddish brown; but in some places the lower beds are composed of a rather coarse conglomerate cemented quite closely together. In the vicinity 19 §UIDLA 18) auypsodery jo satay smyehbal.y bade abi pateraieran peremearcrsnare-t-sbeanins sri De teat Bes Gr gene a med pm arnt I ‘ileal Section Il. X RO pas = = Si a a Fira. . N\. Cret. Nos 2.3 & &. Section at Platte Cafhon. Section IV. SSS Sone SY aaa Remnants. Looking north from near divide between- Platte and Arkansas Rivers. phen Be ie J Ne Wen] GEOLOGY—COLORADO RANGE. SL of Bear Creek and its branches these lower conglomerate-beds fit into the irregularities of the surface of the Metamorphic rocks in a marked manner. Little streams flowing from the mountain-sides have cut excel- lent cross-sections, showing the original deposition of the Triassic (?) sandstones in deep depressions of the granite nucleus. We may say here that the coarseness of the sediments of the lower beds of the Red group is not the only evidence of the disturbed condition of the waters that deposited them; all through the group are quite remarkable illustrations of irregular and obliquelamination. These examples areshown onagrand scale immediately after the Saint Vrain emerges from the granites. There is a considerable valley between the coarse, reddish, feldspathic granites and the first principal ridge of sandstone which has been worn out by the water, butremnants of the conglomerate have been left, filling up the irreg- ular granitic surface. The Saint Vrain here runs southward parallel with the ridges for about three miles, and then turns to the east and cuts through the ridges at right angles, and flows into the plains past Long- mont. Just south of the point where the creek cuts through the belt of sandstones, the parallel valley closes up and the ridges lie close up on the sides of the mountain. Here the group of sandstones which we have usualiy classed as Triassic exhibits a great variety of structure. The conglomerates rest on the coarse feldspathic granites, and the basset edges of the sandstones rise like a wall on the east side of the creek. There are alternate beds of sandstone of various degrees of firmness as well as hardness to resist the atmosphere, and softer layers of sandy clay. The beds of sandstone thicken or thin out at remarka- bly short distances. At one locality on the east side of the creek, the most important bed of sandstone expands within a distance of 200 yards from 50 to 250 feet in thickness, and affords some of the most remarkable examples of oblique Jamination, the lamina inclining 16° to 17°. Here we have quite a broad interval for several miles or more be- tween the granite foot-hills and the uplifted sedimentary ridges, pro- duced by the excavation for the drainage of the Saint Vrain. Soon the ridges lie close on the sides of the granite, and continue more or less closely to Clear Creek. South of Clear Creek narrow intervals occur again to a point about five miles south of the caion of the South Platte. Just south of the Big Boulder the red sandstones seem to have been partially changed by heat, and the ridges rise in lofty walls 1,500 to 2,000 feet above the plain, presenting a front which has no parallel in any other locality along the eastern flanks of the mountains, from the northern boundary to New Mexico. About five miles south of the South Platte Cation we come to the divide between the drainage of the main Platte and Plum Creek, where the sedimentary rocks jut up against the sides of the mountain so that the slope is continuous from the tops of the granite foot-hills down into the valley. This divide is quite narrow, and southward we soon descend into an interval again between the granite foot-hills and the sedimentary region. Between the Platte Cation and this divide there seems to have been an unusual hardening of the Red group, and the action of the eroding agencies must have been peculiar, for the sandstones present a more picturesque appearance than at any other locality, not excepting the “Garden of the Gods” at Colorado Springs. The main ridges seem to have split up into a multitude of irregular ones, and the fragments now stand up inclining eastward 30° to 50° in the shape of leaning columns and spires, the ragged upper edges presenting almost every variety of form which the meteoric forces could produce. These fragmentary forms rise out of the grass and bushes which grow abundant all around a2 GEOLOGICAL SURVEY OF THE TERRITORIES. their base, and one can wind about among them like meandering the streets of some old ruined city. The view from either end, that is from the north end southward, or the south end northward, is very fine, but presenting a confusion of unique forms, the varieties of color, red, mot- tled, &c., adding much to the picturesqueness of the scene. The roof- like sides of many of these broken ridges are peculiarly marked by the vertical furrows down which the rains of heaven have fallen for ages. The opportunity for the study of forms presented here would rouse the enthusiasm of the artist to any extent. It was difficult to estimate the thickness of the Red group, but it appeared to be at least 1,500 or 2,000 feet. The ridgesof No. 1 Cretaceous outside formed a continuous wall about 30° dip. The Jurassic as well as Cretaceous beds are well shown. From the divide between the South Platte and the Arkansas there is a marked change in the character of the sediments composing the rocks above those, usually understood as Cretaceous. This divide rises from 1,000 to 1,500 feet above the valley of the Platte, near Denver, and also about the same elevation as at the north end of the valley of the Arkansas, near Pueblo at the south. The strata are very nearly or quite horizontal, except near the base of the mountains, where they have, in many instances, been slightly disturbed. The full series of beds from the Red Triassic to the summit of No. 5, inclusive, are quite well shown to be the main water-divide near the source of Monument Creek, though obscured here and there by a modern de- posit of what seems to have been swept from the mountains, and must be of the Post-Pliocene age. This latter deposit is made up of the de- composed feldspathic granites and schists of which the immediate foot- hills of the mountains are composed. The red beds also have contrib- uted their portions to this modern deposit. From the source of Plum Creek to the Arkansas it seems to have filled up the irregularities of the — surface more or less, and itis only when it has been swept away that the outcropping edges of the ridges are exposed. ‘There is a certain de- gree of obscurity about the geology of this district. The modern ap- pearance of the group of coarse sandstones and conglomerates above the true Cretaceous beds and their position with reference to the granites induced the belief that they belonged to the Miocene period, and in my third annual report of 1869 I gave them the name of the ‘‘ Monument Creek group.” For a distance of from fifteen to twenty miles they ap- pear to jut up against the base of the mountains with an inclination of not more than 15° at the highest, and usually not more than 3° to 5°; and there is also an apparent unconformability with the older formations. For example, the red sandstones at the north end lie on the sides of the granite foot-hills at an angle of 70° to 80°, and suddenly disappear under the nearly horizontal beds of coarse quartzose-sandstone. It is out of these sandstones that meteoric agencies have carved the remarkable forms which have given names to the little streams and other localities in this region. There is one locality in the valley of Monument Creek called Monument Park, from the great number of columns which are, standing thickly over the surface, each one surmounted with a cap of harder material. The shaft of the column is usually thick at the base, rising up 10 to 20 feet, tapering to the cap, composed of a coarse ag- gregate of quartz-grains, small pebbles, all water-worn, very loosely held together with rather coarse sand cement. The cap is a deep rust color, composed of sand cemented with oxide of iron, and by its greater hardness has resisted more effectually the eroding agencies. I cannot believe that all the effects which we now see were accomplished by the ordinary atmospheric influences at present in operation in this region, y- iar: Tert ark. Monument P 10 olumns i C Leal _GEOLOGY—COLORADO RANGE. 33 although the air, rain, and snow may have done much to give the mopuments their present forms. The greater portion of the erosion must date back into the past, at least to the Post-Pliocene period. It is very probable that water had much to do with the formation of these monuments at atime when there was a far greater supply here than there is at this period. The entire surface of the country must have been on a level with these caps at least, and probably much higher. The caps themselves are nothing more than concretions mostly rounded and flattened, while intervening materials have been slowly worn out and carried away. There is another form of erosion which is character- istic of this formation, and that is the mesas, or table-buttes, which are scattered thickly over a broad belt east of the Denver and Rio Grande Railroad. Most of these mesas are capped with a purplish porphyritic basalt which originally flowed over the surface, doubtless covering a broad area. These buttes, with their flat summits, were also carved out of the horizontal strata, and vary in height from 100 to 150 feet. The rocks composing the “‘mesas” are mostly of a finer material; and above the coarse sandstones of the monuments some of these mesas are nearly round, others square, others oblong. On the east side of Monument Creek and near the divide they assume curious castellated forms, so that they look in the distance like the ruins of old castles. These may be seen in considerable numbers in the distant plains as far south as Colorado Springs. Thereis alarge areain the plains east of the Denver and Rio Grande Railroad line, from Denver to the Arkansas River, which is not well known to the geologist as yet. The pine-covered ridge from which so many streams rise flowing northward into the South Platte and south into the Arkansas, forming what is located on the maps as the Bijou Basin, must be underlaid by rocks which I regard as belong- ing to the Monument Creek group; whether this group as shown here is only a portion of the great Lignitic group or not, the few observa- tions we have made do not determine. The plants found in a number of localities in Monument Creek Valley and near Colorado Springs indi- eate that it is a part of that group—perhaps the upper portion. This group contains beds and seams of impure coal, with deciduous leaves, - some of which are identical with species occurring in the Lignitie strata from New Mexico to the Upper Missouri. Indeed, the general aspect of the rocks in this region is much like the Lignitic group on the Yellow- stone and Missouri Rivers near their junction and in the vicinity. The Monument Creek group has not yet yielded many fossils, and these are not usually well preserved. The rocks are extremely soft, usually dis- integrating easily, and too coarse in texture to preserve plants well. Not an invertebrate fossil has been found as yet, though it is supposed that some very interesting vertebrate remains came from it. More careful explorations will undoubtedly reveal the existence of fossil evidence. Plants are abundant in several localities, and other forms will most prob- ably be found farther east, toward the interior of the basin. Unless these deposits are of modern Tertiary age I am at a loss to account for their position in relation to the metamorphic foot-hills, as well as the older sedimentary beds. A great portion of the Lignitic group has been lifted up at a moderately high angle, as is shown on either side of the divide, but for about ten to twenty miles a group of beds of very coarse texture, an aggregate of crystals of quartz and feld- spar, jut up against the sides of the mountain at an angle of nearly 15°, but usually not more than 8° or 10°. The beds which lap immediately on the metamorphic rocks have the appearance of coarse feldspar granites, and as we recede eastward from the base of the mountains oGs 34 GEOLOGICAL SURVEY OF THE TERRITORIES. the sediments become finer and finer, until the whole group contains a very small portion of the coarse aggregate. It would appear that the sediments of these beds were derived from the mass of metamorphic rocks in the vicinity after they had risen to or near their present eleva- tion. Oi ' The variety of coloring is not so well shown in the Monument Creek group as in the Triassic sandstones of Pleasant Park. The metallic oxides have given a good share of beauty to the former, enhancing the attractions of these singular freaks of nature. Pleasant Park is located among the uplifted ridges of the Triassic, Jurassic, and Cretaceous groups, and the peculiar forms that are worn out of the variegated sand- stones are not even as wonderful as the variety of rich, beautiful shades of coloring. Far north of this point, and south, in the Garden of the Gods, and many other localities, the red sandstones are displayed on a grand seale, but nowhere else are the rich colors, consisting of all shades of red, pink, yellow, gray, and white so well shown. The tints were unusually vivid, and contrasted so as to produce fine effects. This whole region would be a paradise for an artist. The unique forms which have been carved by the elements out of the sandstones are most conspicuous. Near Koontz ranch is a group of weathered masses of sandstone that look like hay-stacks. These rocks are stratified, with the layers in- clining from the mountains to the east 10°. The next point of interest is the district around the east base of Pike’s Peak, in the valley of the Fountain Creek. This little stream rises up in the mountain-range of which Pike’s Peak forms a part, flows south- east, cutting through the upheaved Sedimentary ridges, after emerg- ing from the mountains, nearly at right angles. The ridges on the north side of the creek trend a little east of south, but immediately on the south side flex toward the mountains at a sharp angle, trending west of south and very soon apparently striking the granite mountain-sides and are thus cut short off. The entire group thus forms an obtuse angle, and Fountain Creek has carved out its channel pretty directly through the angle. The channel therefore affords a most excel- lent opportunity for the study of the formations in their consecutive relations. But the question arises, how is it that they are developed to such an enormous thickness so suddenly? Has there been an increased deposition of sediments at this particular locality? I have already alluded to the absence of all rocks below the supposed Triassic or red beds along the flanks of the mountains from the Union Pacific Railroad to Colorado Springs. We may, then, ask why it is that there should be exposed here so suddenly, not only an unusual development of the Tri- assic or red group, but below it 1,000 to 1,500 feet of reddish and gray sandstone-quartzites with intercalated beds of clay of varied thickness, probably Carboniferous, and below this a group of limestones more or less impure resting unconformably on the Metamorphic rocks contain- ing well-defined Silurian fossils. There cannot be less than 4,000 feet of sedimentary beds below the Cretaceous No. 1 exposed in the valley of Fountain Creek, while for a distance of one hundred and fifty miles north of this point the aggregate thickness of the Triassic and Jurassic groups is probably not over 1,500 feet at any locality. The little streams that flow down from the mountain-sides have cut deep caiions through the Silurian bedsas they lie high upon the granite foot-hills, and deep into the granites also; so that the opportunity. for special studies is as complete as could be desired. Mostexcellent sections can beobtainedin Williams's. Cafion, Chiann Caiion, and in a dozen gorges extending along the mount- ains for about five miles. My time was so limited that, even with Fig. 6. 2a ise | poy! SS ale =———==:... _——_ __——— => inte == a Seer oO LT ee one “ —— ——= Eee Crushed Strata. Oblique Laminz. SUA aR oe GEOLOGY—COLORADO RANGE. 35 the facilities afforded by these natural sections, only a partial examina- tion wasmade. ‘There is an area here of about ten or fifteen miles square that must ever remain an interesting field for the practical geologist and deserving of a special exploration. One may follow Williams’s Cation up two or three miles above the springs through a narrow gorge with walls rising 300 to 500 feet on either side. At the entrance to the cafion the red beds rest on a yellow-gray limestone which passes down into an arenacecus limestone with a reddish tinge containing well-marked Silu- rian fossils. The inclination of all the beds is about 35°, and the mass runs high up on the mountain-sides, resting unconformably on the coarse feldspathic granites, as shown in the illustration. The lowest beds of sedimentary rocks are rather coarse sandstones, and conglomer- ate made up of water-worn quartz-pebbles, with very irregular laminz of deposition, the whole reminding one of the Potsdam group. Abdut two miles up the caiion the Silurian beds, inclining southeast 8° to 10°, rests on the feldspathic granites, which are most distinctly stratified, the strata inclining about north 35°. The sedimentary beds fill up in a remarkable manner the inequalities of the original surface of the meta- morphic rocks. The Silurian group was noticed by me in 1869, and a col- lection of fossils was made, but the fossils were not identified by Mr. Meek until it was too Jate to use them in my third annual report. In the: fourth annual report, 1870, on page 295, several species of Silurian fossils are mentioned by him belonging to the collections from this locality. One of the species, aecording to Mr. Meek, is a well-known form in the Caleciferous group of New York, Ophileta complanata. There is considerable variety in the aggregate of beds here, which may be. regarded as Silurian, and we may conclude that the Potsdam group is quite well represented, and that it is possible that some of the higher divisions occur. These rocks require a still more careful study, yet it is an interesting fact to know of their existence in this locality. In the lower sandstones I found a species of Lingula, the pres- ent season, probably a Potsdam form. I have never known of any Car- boniferous fossils being found here, but Iam confident that there are 1,000 to 1,500 feet of these beds between the Silurian group and the true red beds or Triassic. They are composed mostly of sandstones, quartzites with partings of clay variegated. About four miles to the north the Silurian limestones form high ridges on the sides of the mountains for a short distance, then disappear entirely. There seemed to be an ap- parent unconformability here. I studied the structure of the upturned edges from every point of view, and I could not decide on a real non- conformity. There were localities where the Silurian group is entirely separated from the red beds, and inclining at different angles, but at the upper end of the “Little Garden of the Gods” the order of sequence appeared te be unbroken. We may now ask how 2,500 to 3,000 feet of rocks disappear so quickly and mysteriously, as we go north of Fountain Creek. The red sandstones that we have been in the habit of regarding as Triassic rest upon the granites as if they had been deposited there by water originally, but partook of the elevation of the mountain- range. Wemay suppose that the Silurian beds once covered this entire region, and that over large areas they were worn away prior to the deposition of the overlying beds, and that the portions we see at this locality are remnants that escaped the great erosions, or we may Suppose , that they were not deposited. 1 believe the former is the true inter- pretation, that the Silurian rocks once covered the entire country and may still exist toa greater or less extent under the vast thickness of 9 36 GEOLOGICAL SURVEY OF.THE TERRITORIES. more modern beds which underlie the plains from the east base of the mountains to the Missouri River. The plateaus between Monument Creek and the upheaved ridges are formed to a great extent of a thick deposit of materials of quite modern origin. There are ashen-brown and gray clays covered with a consid- erable thickness of a sort of unstratified drift material, composed mostly of the débris of the Metamorphic rocks, the red feldspathic predomi- nating. This curious deposit fills up the inequauties of the surface in many places produced by the disturbance of the older sedimentary beds. Between the railroad-depot at Colorado Springs and the “ Little Gar- den of the Gods,” the road. passes over a beautiful plateau, from which the view of the country in all directions is exceedingly fine. This pla- teau is underlaid by the modern deposit, and here it must reach a thickness of 200 to 400 feet at least, and possibly more. The origin and time of this deposit is somewbat obscure as yet, but an attempt will be made to clear up its history in another place. It is undoubtedly Post- Pliocene, and belongs to some portion of the Post-Glacial era of this region. The deposit may be seen with a greater or less thickness all along the eastern flanks of the mountains, and is composed of the ma- terials worn from the rocks in the immediate vicinity. In treating of — the influences of water and ice in carving out the present mountain- forms, I shall dwell more fully on this subject. CHAPTER II. COLORADO MOUNTAINS, SOUTH PARK, PARK RANGE, UPPER ARKAN- SAS VALLEY. In order that the annual reports may be read with greater interest by the general public, I have presented the-matter in a narrative form as far as possible, stopping here and there to discuss a topic more in detail as it is suggested by some peculiar feature along the route. This plan has enabled me heretofore to introduce more readily local details of interest, both of a practeal as well as scientific nature. Our starting-point was Denver, the most important town in Colorado. The country between Denver and the mountains has already been de- seribed in so much detail that we will hasten on toward the South Park by the old stage-road. After passing the base of tue mountains we meet with only changed rocks, until we descend into the depression, or basin, known as the South Park. The metamorphic schists and granites in their almost numberless varieties which compose the central . portions of these mountain-chains will be discussed by Mr. Marvine, who spent most of the season among them. We entered the mountains by way of the Turkey Creek Caiion ; here we had a most excellent opportunity to study the connection of the Triassic rocks with the underlying metamorphic. The coarse sediments of the Triassic were deposited upon the irregular surface of theschists, of- tentimes filling up deep depressions. The caiion has been carved out of the schists so that they can be studied with ease on either side, and as the stream passed through the sedimentary beds toward the plains the most perfect cross-sections were made. The stratification of the schists is - even more distinct than that of the sedimentary beds. The south side | of the cafion is very rugged and precipitous; the inclination of the schists Cathedral Rocks—Garden of the Gods, Colorado. SeoEe | GEOLOGY—SOUTH PARK. Sar is such that the basset edges project from the south side, while on the north side the slope is quite moderate. The cafion is partly one of fracture as well as erosion. The stream has not cut the strata quite at right angles, but slightly across the dip. The principal rock is a very hard, black gneiss or schist, with seams of yellow feldspar, varying from a few inches to several feet in thickness, running across the strata at different angles. Some of the seams contain quite large masses of quartz, but feldspar predominates. Sometimes the quartz is interstrati- fied with the schists for a short distance, running out, however, at both ends. In cutting the road along the north side of the Turkey Creek Cafion an old dike is exposed, with feldspathic quartzite on one side and a seam of feldspar on the other. The dike-matter is filled with masses, of greater or less sizes of the adjacent schists. -This dike weuld never have been exposed but for the wearing out of the gorge by water and ice. Igneous rocks of different ages are thus exposed at various locali- ties all through this front range; seams of quartz or feldspar are so numerous, intersecting the schists in every direction, that it would re- quire a most detailed study to describe them properly. Pockets of mica occur frequently in these seams. About a mile up the canon are two dikes of syenite 10 to 15 feet wide, rising up in the form of a wedge, but separated by about 8 feet of feldspathic granite. The schists here present to the eye the appearance of utter chaos. The study of the details would reveal a warping of the bedding that would be quite remarkable. Layers several feet thick are warped, or dished, at least half the circumference of a circle. The aggregate inclination seems to be 20° east of south. The lower thin layers of schist are in some places crushed in a remarkable degree, while higher up toward the summits are thick massive beds of feldspathic granite in a horizontal position. For about five miles up the cation the scenery is very rugged on both sides, the valley widens out somewhat, and the mountains on either side soften down and are covered more or less with debris and thin soil, on which grow grass and pine trees. Near the junction and for some miles beyond the recks are massive granites, of which the- great mountain- peaks in the vicinity are composed. ‘The surface is covered with groups of weather-worn granitic masses resembling old ruins. The: peculiar forms of these masses determine to a great extent their texture. The coarse feldspathic granites disintegrate easily, and peel off in thin, cir- cular layers, giving to them a smooth, rounded appearance, while the finer-grained, more compact granites are still angular. The varieties in texturegive form co the surface-scenery over a very large area, and no- where is this fact better illustrated than in these mountain-districts. The great orographic lines were undoubtedly determined by upheaval, but the present surface-forms were due largely to erosion. We shall endeavor to show, from time to time, that sufficient importance has never been attached to this agent in molding the lineaments of the earth’s surface; that although the proofs of upheaval are everywhere apparent, and in many localities most probably those of depression, yet the immediate forms of the surface thus produced have almost entirely disappeared under the effects of erosion or weathering. Many of the water-courses have probably followed lines of fracture, so that the two agents, upheaval and erosion, may have united to produce many of the mountain-valleys. Thereisone interesting feature in connection with the mountainous districts of Colorado, which is now apparent in the valleys of the Colorado or front range. These grassy areas are fast being occupied by a mountain-population, sparse, it is true, but a very thrifty one. The grass not only covers the valleys in the elevated regions, but 38 GEOLOGICAL SURVEY OF THE TERRITORIES. grows high up on the mountain-side, so that it is remarkably well adapted for dairy purposes. A large amount of the best butter and cheese is made, and the demand is greater than the supply, as yet. Most of the hardy garden-vegetables and some of the cereals grow well at an elevation of 6,000 to 8,000 feet. These mountain-ranches are every year filling up the more elevated regions of Colorado, so that we may conclude that no portion of the Territory, even aside from the min- eral wealth, is practically unavailable to man. From the high mountain-hills that border the north side of the South Park we have a fine view of the great basin-like depression. The sur- face of this basin is not entirely a plain, but is covered to a greater or less extent with low ridges and hills, which trend about southeast and northwest. The dish-shaped character of the depression, as well as its origin, is plain, when we come to examine the borders. We find the sedimentary rocks lying high up on the sides, showing clearly that these strata incline: in every direction toward a common center. In other words, the South Park may be regarded as an immense quaquaversal. On the north border, the sedimentary rocks are very much obscured by the great deposit of mountain-drift and the igneous rocks that seem to concentrate there to a great extent. Fragments of sandstone, appar- ently of the Triassic group, cover the hills, and here and there we see an outcrop of the main beds, but not sufficient to make a connected sec- tion. At one locality there was a circular depression surrounded with a wall of trachyte, with a small lake in the center, which was undoubt- edly an old crater. There is also a great thickness of trachyte here in layers, varying from an inch to a foot in thickness, inclining from the hill at first 45°, then increasing to 65°, showing that after the first out- .flow had cooled there were subsequent outflows elevating the cooled portions at a high angle. Passing along the road to the southwest, toward Fairplay, we see all along the borders of the park a terrace, which seems to have such a uniformity of level that it points to the existence of a lake here at a comparatively modern period. There is also a very beautiful valley like area here, which occupies about one hundred square miles. Near Lech- ner’s ranch a shaft has been sunk about 30 feet deep, cutting a coal-bed about 12 feet in thickness, with a dip of 45° northeast,.and a strike south 45° east. The clay above the coal is about 6 inches, and be- low the coal 10 inches. thick. Below the lower clay is a sandstone, at the bottom of the shaft, and aboye the upper clay a bed of yellow soft sandstone. About 200 yards to the west another shaft has been sunk, exposing a bed of coal 6 feet thick. Iam inclined to think there are two-different coal-beds here, though there may be but one. ‘The slope underlaid by the coal strata extends up close to the sides of the mount- ain, and the surface is so covered with drift that it is only by means of these shafts that the Lignitic beds can be seen at all. A few fragments of deciduous leaves have been collected here, showing clearly that a portion of the Lignitic group, as seen on the east side of the mountain- range, occurs here. As we pass along the road to Fairplay, we travel over the entire series of sedimentary beds known in the park. Long ridges extend across the basin, composed of the black shales of the Cretaceous, containing Jnocera- mus, Ostrea, Scaphites, the well-known Baculites ovatus, &c. The entire series of Cretaceous, Jurassic, and Red or Triassic group are well shown. Toward the center of the park are some long ridges of trachyte, which must have been produced by the outflow of igneous matter from an ex- tended fissure. The sedimentary beds are exposed more or less all along HAYDEN.) GEOLOGY—SOUTH PARK. 39 the east side of the park. They slope up close on to the east side of the Park range, but the wash or drift from the mountains has so covered the slope that the beds iu contact with the Metamorphic rocks can sel- dom be seen. Along the valley of the Platte the drift-material, consisting mostly of water-worn bowlders, is immense. The entire mass of drift- ‘deposit, in which the placer diggings are located, has been washed down from the valleys of the little “streams of the ‘South Park. The local origin of the drift, so far as our Rocky Mountain districts are concerned, is illus- trated 1 in a remarkable manner in the park. The area of the park is about 1,200 square miles; its greatest length is northwest and Southeast, about forty miles, and in the opposite direction about thirty miles. The shape is elliptical. The general ele- vation varies from 8,000 to 10,000 feet above the sea. The drainage is from the northwest to the southeast. Before presenting any details of the geology of the Park range I will state briefly what I believe to be its relation to the great Sawatch range, on the west side of the Arkan- sas River. J am of the opinion that the Park range is a portion of a gigantic anticlinal, of which the Sawatch range is the central axis; that the Park range is a portion of the east side of the Sawatch range, and that the ereat valley of the Upper Arkansas is mostly the result of ero- sion through the granite rocks. The eroding agents began their work in a fissure produced by the uplift, but once a depression or opening formed for the accumulation of water and ice, the work of disintegra- tion would commence. The subject of earth-sculpture, or erosion, as it is illustrated in myriad forms in the Rocky Mountains, and nowhere i in the West on 3; grander scale than in the mountains of Colorado, will be touched upon frequently in this report, and will be treated more fully, under a separate head, at some future time. The Park range is ver y irregular in elevation. Portions of it are low, while several peaks rise about 14,000 feet. Mount Lincoln is 14,183 feet, and upon the very summits are found the sedimentary rocks. The action of the internal forces has been very irregular also, sometimes lift- ing the granite nucleus up to an elevation of 12,000 to 14,000 feet in the form of pufis, as it were, the sedimentary beds inclining at various angles and in different directions fromits sides. The aggregate inclina- tion of the strata is plainiy to the eastward, and the gentle slopes are on the east side of the range, while on the west the sides are very ab- rupt, and in some instances the rocks overhanging, so that the general form or outline of the Park range would indicate that it might be regarded as a portion of an anticlinal. All along the east side of the Park range are numerous gorges, which extend down from the crest and gradually expand out into moderately wide grassy valleys. Immediately after leaving the gorge, however, the drift-material is very great, covering the valleys and lying high upon the mountain-sides. These gorges usually commence near the water-crest in a somewhat extended amphitheater, which is constantly enlarged by the breaking down of the sides. These gorges all point to a common origin, and have no doubt been carved out by the combined action of water and i ice. The morainal matter brought down by the old glaciers is shown most abundantly in the lower portions of these gorges as they expand out into the valleys that open into the plains. The evi- dences of ancient glacial action are quite abundant all through the Park range, but far more remarkable proofs are found in the Sawatch range. These facts will be noted more fully in another place. From Fairplay we follow up the valley of the South Platte for ten 40 GEOLOGICAL SURVEY OF THE TERRITORIES. miles, and arrive at the base of one of the spurs extending from Mount Lincoln, known in the country as Mount Bross. The entire mountain is so thickly covered with surface-deposits that the angularities are smoothed off, and the grass and flowers are quite abundant almost to the summit. We find, however, on the summit, and around the sides of the upper portion, remnants of the sedimentary beds, quartzites and limestones, but the nucleus is a schistose granite. Silver-mines are opened everywhere on the sides both of Mounts Bross and Lincoln. On the latter peak there are mines of considerable value, which are wrought by a company, full 14,000 feet above the sea and within a few feet of the summit. The Montezuma mine is located within 100 feet of the top. The silver-ores are confined mostly to the limestones and quartzites, and are segregated, as it were, in the fissures in the most irregular manner. There seem to be no regular lodes, but they are like the silver-mines in the limestones and quartzites of Utah. Indeed, the formations are so similar that a description of one locality would apply substantially to the other. The mountain is composed mostly of schist- ose gneiss, with the lines of bedding very distinct, and unconformably upon it rest the secondary beds. The quartzites, mostly crystalline, partially changed by heat, rest on the edges of the schists, then comes a blue impure limestone full of pockets and seams of quartz. Above comes a thick bed of quartzites again, the whole mass a thousand to fifteen hundred feet in thickness. The summit of the mountain is a dike of porphyritic granite, which seems to have burst up in the form of a wedge through all the sedimentary beds. The sides and summits of the mountain are so covered with the broken masses of rock, mingled with igneous, granitoid quartzites and limestones, that it is very diffi- cult to obtain a clear section. On the east side of the mountain a sort of gorge has been worn deep down between Bross and Lincoln, expos- ing in the vertical sides the order of superposition quite clearly. The view from the summit of Mount Lincoln is wonderful in its ex- tent. To the east, far distant, is distinctly seen Pike’s Peak, with the contiguous ranges which border the east side of the park and extend northward toward Long’s Peak, all of which are granitoid. On the west and northwest side of the park is a vast group of high mountains, gashed down on every side: with deep gorges with vertical sides, reveal- ing the strata of quartzites and limestones resting on the schists with dikes of the trachyte. To the southward can also be seen the granite nucleus, a remarkable range of mountains, the Sawatch, which, with its lofty peaks—among them Mounts Yale and Harvard—looms up like a massive wall, with a wilderness of conical peaks along its summit. To the east and southeast the park lies spread out to the view with its variety of low ridges and meadow. These ridges are composed of all the sedi- mentary beds uplifted known in this region. Some of them, covered with basalts, with a trend nearly north and south, extend in regular order far across the park, eastward. From the top of Mount Lincoln more than fifty peaks rising to an elevation of 13,000 feet and upward, and above two hundred over 12,000 feet, can be seen. Probably there is no portion of the world, accessible to the traveling public, where such a wilderness of lofty peaks can be seen within a single scope of the vision. The limestones and quarizites incline down the north slope of Mount Lincoln to Hoosier Pass, which separates the waters of the Platte from those of the Blue River. The trend of the curious dike that caps Mount Lincoln is about southwest and northeast. Silver-ore occurs to a great a GEOLOGY—SOUTH. PARK. Al extent in pockets, some of which is very rich, yielding $500 to the ton. Much of it is the decomposed carbonate, like the gulch-ores. On the east side of Mount Bross is located the Moose mine, which - has yielded a large amount of valuable ore. The greater part of the ore is taken from the limestone. Before going further I will state what I believe to be the age of all the limestones and quartzites which seem to cover the highest mountains, and in which most of the valuable mines are found. I think there is no doubt that they belong to the Potsdam group, though I was unable to discover any fossils. Doctor ‘Peale found a few obscure forms which indicated that the group is of the same age as those next to the granites in Utah, which we now know are of that age. In Mosquito Gulch we find the sedimentary beds dip- ping southeas’ 20° to 25°, and toward the head of the gulch the schists incline 15° in the same direction. There are most remarkable faults by which the mass of sedimentary beds are dropped down 200 to 400 feet directly, so that the schists jut up against the limestones or quartzites; these faults are very common. The 1 underlying metamorphic rocks are made up in part of quartzitic sandstones, full of rounded pebbles of quartz, “which would indicate that they might belong to the Lauren- tian series. The slides in this gulch are a prominent feature. Im- mense masses have slidden down from the sides of the mountain, in some instances a thousand feet or more, forming irregular terraces. The faults are really very remarkable on both sides of the gulch. The slides produce broad depressions near the base of the walls, in which the waters accumulate, forming lakes, and these are the sources of the little streams. The hundreds of gorges which have been carved deep down into the sides of the mountains form channels for the little streams that are fed by the melting of the snows near the crest. All these little streams eventually uniting form the larger streams that traverse the plains. Each one of these little branches starts from one of these small emerald lakes, far up in the amphitheater, near the very water- divide. Thus we can see that the miniature lake is a prominent feature of mountain-scenery, and from the summit of some high mountain-peak hundreds of these little emerald lakes may be seen nestled high up in the very head of the gorges. They are not large, varying from 100 feet in diameter to half a mile or a mile; seldom more. On the summit between Mosquito, Birdseye, and Evans Gulches, broken masses of the quartzites and trachytes seem to have moved down a considerable distance from their places, and are deposited in the form of windrows, as if there had been glacier movements here. It is undoubtedly due to the combined action of water and ice, so that there was a slow movement of the masses ot ice and snow down the slope, and in gradually melting left those singular rows of rock. At the head of Evans Gulch there isa fine exhibition of a dike parallel with the strata in a nearly vertical wall 2,000 feet high. The quartzites and limestones pass beneath 1,000 to 1,500 feet of trachyte. The latter present the appearance of having been elevated with the stratified rocks, and incline in the same direction. The dip of the trachyteis 10°, and the underlying limestones and quartzites about 10° to 15° south. east, then about 1,000 to 1,500 feet of the quartzites and limestones. There is here a portion "that inclines in an opposite direction, west, toward the Arkansas, but this is probably caused by the sliding down of the .mass. The dr alnage of Evans and Birdseye Gulches flows into the Ar- kansas. Great masses have fallen down on the sides of the mountain, so that prodigious faults occur everywhere, and the form is that of irregu- lar steps. Although examinations were made here in midsummer, yet - te ‘ A2 GEOLOGICAL SURVEY OF THE TERRITORIES. the sides of the mountains were covered with little streams of water fed by the melting of the snow, and the great loose masses of super- . ficial earth and fragments of rock moved slowly down the slope like a glacier. . One of the peculiar geological features in this range is the trachytic beds, which appear to be interstratified with the older sedimentary rocks. These igneous layers vary much in thickness, and appear or dis- appear, reach a thickness of 1,000 feet or more, and diminish in a short distance to a few feet, or disappear entirely. And yet, upon the out- cropping face of the great uplifted ridges, or in the deep gulches where ° not unfrequently 2,000 vertical feet of rocks are shown in their order of superposition, these trachytes seem to have flowed out over the surface of the Silurian quartzites, or, in other words, are interstratified among the old Silurian limestones and quartzites, as if they might be cf the same age and have been elevated with them. It is probable that they are not older than the Tertiary period. On the summit of the pass or divide between Mosquito Gulch and Evans Gulch, where the great vertical walls which face the Arkansas are so well shown, we have several hundred feet of the quartzites in- clining at a small angle, and resting directly on a great thickness, 800 feet at least, of unstratified trachytes. At the base, resting on the schists, are quartzites with micaceous sandstone; pudding-stones, made up of rounded pebbles of quartz, passing up gradually into a yellow arenaceous limestone, then into a blue limestone rather cherty, then up into a brown guartzite upon which the trachytes rest. This peculiar structure in- cludes all the prominent peaks of this range, extending ina nearly north and south line from Buffalo Peak, south, to Quandary, north, and I know not how much farther. There are so many points dependent on the com- pletion of the topographical maps, and the detailed reports of the assist- ant geologists, that these preliminary reports must necessarily be very imperfect. The summing up of these detailed and preliminary reports, which must constitute our final labor, will unite the whole work, the same as the great preliminary triangulations link together into one~ whole the detached topographical districts, on the final map. An examination of the map will show the water-divide between the source of the South Platte and its branches and the Arkansas. Hach one of these little streams cuts a deep gorge from the crest down 1,000 to 2,000 feet, with more or less vertical walls on either side. Nearly all of these gulches, or gorges, have been worked for gold, and the moun- tains prospected for silver; thus the miners have given them local names the origin of which is in most cases obscure. The superficial deposits have been in many cases almost entirely worked over by the enterpris- ing miner for gold. Placer-mining all over this region has yielded great and brilliant results, but of course they can never be of a per- manent character. All along the west side of the Park range, from Quandary Peak to Buffalo Peak, we pass from one gulch to another in quick succession; each one of which has employed the enterprising miner to a greater or less extent in search of gold. Not less so the east side; but we will follow our line of travel, examine the west side for a time, and then return to the east slope again. One of the most noted of the mining gulches in Colorado is the Cali- fornia Gulch. About four millions of gold have been taken out of the placers. There are a few parallel lodes that run about 10° west.of south . and east of north. Three of the lodes would average about 10 inches between walls. The Five-twenty lode has been worked to the depth of 125 feet and 200 feet in length. The Pilot is a ‘‘chimney” lode, and is a Mi HAYDEN. ] GEOLOGY—SOUTH PARK. 43 sometimes 80 or 90 feet wide, then closes up and disappears. About $40,000 of gold has been taken from it. Many of these lodes spread out in every direction in small branch seams, and lines of fracture run in every direction, filled with ore, occasionally very rich. Sometimes these branches will come together in one lode and again spread out, thus be- coming a great source of perplexity and cost to the miner. The Printer Boy is probably the most valuable lode in this gulch, and has yielded rich results to the company. It is managed by two very polite and in- telligent gentlemen, Mr. J. Marshall Paul, formerly of Philadelphia, and Mr. Charles Hill. This lode has now been explored for a horizontal dis- tance of 3,000 feet. The width between the walls varies from 4 feet to 10 or 12, but sometimes pinches up to not more than an inch. The group is mostly decomposed clay with now and then masses of quartzite. One hundred and twenty thousand dollars of gold have been taken out of this lode, which inclines about 6° to the west. Carbonates of cop- per and lead, iron pyrites, zine blende, &c., are found. The walls are remarkably well defined. Up to this time only the decomposed ore has been taken out. There is connected with this mine a successful 15-stamp mill, to which 10 stamps more are to be added. It is supposed there that the yield of gold will be $1,000 per day. In California Gulch, as ‘in all the other gulebes, the drift material is very great and entirely local. Trachytes, quartzites, and some limestones compose the rocks; the iron ores are abundant, and in the lodes there is much iron pyrites. The vast amount of the oxide of iron, mingled with the loose detrital deposits, gives character to them. The clays have an intense rusty-yellow color, _and the broken rocks and pebbles are often cemented together into a conglomerate. The oxide of iron covers and permeates all the superfi- cial deposits, which are very thick. These thin out toward the head of the gulch, but thicken down to the expansion of the gulch into the Arkansas Valley. At the head of Stray-Horse Gulch a very valuable iron mine has been opened. The stray masses of hematite that cover,.the surface, mingled with the drift, are abundant, but the detached masses from the moun- tains cover the lower portion of the slope to such an extent that, even in the channels of the little streams, it is difficult to find the basis rocks. The prospector followed the float-eres up to a certain elevation on the side of the mountain, and where it ceased to appear he sunk a shaft and found the vein at no great depth. This vein is well shown in places in lowa Gulch, extending directiy across the strata in a direction a little west of north and east of south, and here it is at least 100 feet in thick- ness. It appears high up in the south wall of the gulch, so that its relations with the other rocks are apparent. The vein is at least 100 feet in width, and must have been segregated in a great fissure passing down through the quartzites into underlying schists. It must extend along the sides of the mountain for several miles, for the distance from the opening near Stray-Horse Gulch and Iowa Gulch is about six miles. This indicates a vast body of iron ore in this region. The iron-ore bed trends about north and south, and extends down nearly vertical through the quartzites. The iron ore is said to carry gold enough to pay mod- erately. Excellent galena, carrying silver, is found in the quartzites near the iron vein. On the south side of Iowa Gulch there is an immense accumulation of trachyte, gneissic, and quartzite bowlders, the former predominating. _ The quartzite has fallen down from the north side of the gulch, while the gneiss has been brought down from the head of the gulch by glacial action. In the side of lowa Creek we find the blue limestone lying 44 GEOLCGICAL SURVEY OF THE TERRITORIES. ~ over the speckled trachyte, quite compact, without lines of bedding, and much changed, showing the effect of the igneous rocks below. We can see here that the igneous rocks must be ‘of comparatively modern origin, and must have been intruded between the strata, forming a con- Spicuous agent in the uphift. At the head of Iowa Gulch, on the south side of the stream, the mas- sive granites rise up 1,000 to 1,200 feet, with a cap of the quartzites. It is from this exposure that the great masses of granite scattered over the lower portion of Iowa Gulch were derived. At the head of the gulch the strata are greatly faulted. The varieties ef texture in the granites are numerous, and it appears more massive and older than any before seen in this range. It is much broken by irregular jointing, but no lines of bedding can be seen. The great amount of broken masses, most of them more or less rounded, which are scattered over the sides and bottom ef these gulches, is mar “velous. There is less of this glacial evidence in the Calitornia Guleh than in any of the gulches on “either side. This granite nucleus, or uplift, seems to extend across the heads of the guiches in a north and south cour se, while the streams that flow down the west side of the range cut through this granite nucleus and have their origin in the stratified rocks that incline from the east slope. This, however, is not an uncommon occurrence. There is a constant tendency in these mountain-streams to wear these gorges back beyond the true axis on either side. Hach one rises in a sort of amphitheater which has been formed by the breaking down of the sides of the gorges by the water and ice in the fissure, and the melting of the snow sweeps the fragments slowly down into the guich. This gnawing process, as it might be called, at the mass of the mountain has been going on for ages, so that in many places the crest is a single sharp ridge between the amphitheaters on either side. In many places this erest is worn through, and many of the low passes were once high walls wholly inac- -cessible. The great mass of sedimentary stratified rocks of which this range is largely composed inclines away south of east from this granite nucleus, showing clearly its anticlinal structure. The granite, as seen in Iowa Gulch, is a true “ wedge,” the quartzites capping the summits inclining in opposite. directions, a portion dipping west at an angle of 10° or 120, Although, in general ‘terms, many of the mountains are illustrations of the single wedge structure, I have never seen a clearer exhibition than this, where the granite is capped with the quartzite strata, and the eroding agents have sliced it down vertically, so that the relations are seen perfectly. The amphitheater at the head of Iowa Gulch is about 10,500 feet. In passing over the crest into Horseshoe Gulch we are obliged to climb an almost vertical wall for 1,500 feet. Resting upon the granites at the bottom are about 200 feet of quartzites distinctly Stratified! Above the quartzites are 800 to 1,080. feet of unstratified sombre-gray porphyritic trachyte, breaking off in vertical columnar masses. Over the trachyte comes quartzite and arenaceous limestone, passing up into about 50 feet of ver y cherty, partially metamorphosed, limestone, in which the galena mines are located; above this are alter- nations of quartzites with beds of limestone, 2,500 to 3,000 feet in the aggregate, in the range. Thesummit of the divide i 18 about 12,500 feet ; the high: peaks, north or south, rise upward of 13,000 or 14,000 feet. The summits and sides of the range are covered with fragments or dé- bris cf broken trachyte mingled with quartzites, the former predomi- . nating. At the head of Empire Gulch the granites rise up nearly to the sum- HAYDEN.] GEOLOGY—SOUTH PARK. 45 mit, while the stratified quartzite cap only the highest peaks of the Horseshoe aud other cones in the vicinity. The quartzites here are very hard, but brittle, breaking into small fragments greatly meta- morphosed, though distinctly stratified, and remind one of the quartzites of the Uintah Mountains. Below the massive quartzites are very hard limestones, out of which considerable quantities of silver-ore are taken. Below the limestones are 50 to 80 feet of a peculiar rock, composed largely of yellow jasper. The dip of the strata in the north branch of the Horseshoe is about 21°, and in the Horseshoe itself about 159°, north of east, though it is quite variable. The Horseshoe is a most singular mountain-form. The excavation here has wrought out a circular or semicircular form, which suggested the name of Horseshoe Mountain. On the south side a ridge runs down the gorge-like valley for four miles, with an average dip of 13°, and then a high mountain occurs, in the base of which the gneiss projects up 500 feet, while on the east side and on the summit the lowest quartzites are again seen in contact with the gneiss. The most remarkable faults in the strata occur here. In the carving out of the Horseshoe amphitheater the granitic schists are ex- posed at the bottom, and continue down for a short distance, when they are concealed by the débris. Only the stratified beds are seen in the walls of the guich on either side. Here and there the schists rise up to considerable heights. The sedimentary beds may rest on the schists lower down in the valley, or on the high peaks 2,000 feet above. The remarkably irregular surface of the underlying schists is hardly due to erosion prior to the deposition of the sedimentary rocks, but to the internal forces that have thrown all the rocks in this region into such a remarkable chaotic condition. We do not find here the intruded beds of trachyte on quite so large a scale as on the west side of the range. The trachyte, however, shows itself about four miles below the depres- sion of the Horseshoe, changing all the rocks to a greater or less extent with which the igneous material comes in contact. This gulch has reaily three heads, of which Horseshoe forms the middle. The evidence ot the gradually slow excavation of these amphitheaters is well shown in each. That the wearing out of the depressions may have been more rapid in former times I do not doubt; perhaps, during Glacial or Post-Glacial times. We shall hereafter discuss the subject of the great Glacial period, which must have held sway over all this region. Ice, snow, and water are still important agents, though their action is slow and the resuits hardly perceptible in a century. It would be diffi- cult to fix any very definite angle of inclination for the stratified rocks. Sometimes it is nearly horizontal, and again nearly vertical. In the Horseshve district the dip will vary between 12° and 25° generally. A typical section of the sedimentary rocks in this region may be found in the gulch to the south of the Horseshoe. The strata which rest upon the schists there present a nearly vertical wall for about 800 feet. The schists as they occur in the bed of the stream appear to be vertical, with grayish brown quartzites resting directly on the edges, passing up into a cherty limestone. This is quite variable in texture, though the joint- age and lines of stratification are clear. On the southeast side of the gulch, at the very head, there is a massive wall of quartzites and lime- stones 800 feet high ; then comes a bed of intruded porphyritic trachyte, about 400 to 600 feet thick, and above this comes 300 feet of very hard dark brown quartzite, evidently partially metamorphosed. Then comes an interval, obscure on the surface, but composed of a dark slaty shale, with layers of dark impure limestone. There are alternate beds of limestone, quartzite, sandstone, and shale through what I estimated to AG GEOLOGICAL SURVEY OF THE TERRITORIES. be 1,500 feet of Silurian strata, and 2,000 feet of Carboniferous beds. The upper portion of the latter is nearly all coarse, rusty, or gray sand- stone, while the lower half contains many beds of shale, with layers of limestone containing great numbers of well-marked Carboniferous fossils, as Trilobites and Productus. In the Silurian group the first bed of trachyte is quite massive, and must correspond with that seen on the west side of the range. The jointage is perfect, and the mass breaks into huge cubical blocks. Some of it is laminated vertically, as if composed of thin layers tipped on end. Higher up are several beds of the trachyte, varying from 15 to 30 feet in thickness. Jt was not possible to fix a line between the Silurian and the Carboniferous groups, in most instances. I shall only speak of these formations in general terms, referring the reader to the carefully-wrought section in Dr. Peale’s report. Asa general rule, it is only at the very heads of these gulches that the basis rock can be seen. The process of erinding to powder, as it were, by ice and water, has been carried on to such an extent that the entire valley is covered thickly with earth, filled with more or less worn rocks, of every size, from that of a pea to several feet in diameter. The snow, melting upon the crests of the mountains, saturates these superficial earths with water, and they slowly move down the gulch much like a glacier. This is another process of grinding the underlying rocks, smoothing and grooving them. Underneath these superficial deposits is what the miners call the “‘ bed-rock,” and it often involves immense labor to strip them off to reveal the mineral lodes. As we pass down Horseshoe or Four-mile Creek we soon find that the vast amount of loose material covers everything, rendering the suc- cession of strata very obscure above the Carboniferous, yet we know that there is a full series of tie red beds, Jurassic and Cretaceous, up to the summit of the Lignitic group, inclusive. The upper group inclines away from the base of the main Park range far eastward into the Park. Pass- ing northward from Fairplay to the Little Platte or Twelve-mile Creek, we find the foot-hills correspond to the more modern sedimentary beds, inclining at all angles. In the channel of a little stream, about ten miles south of Fairplay, the Triassic and Jurassic beds are exposed to some extent, dipping 30° to 40° east or southeast. The foot-hills all along the west side of the Park appear to be composed mostly of the red group, lapping on to the sides of the mountain. The Carboniferous and Silu- rian groups are seen on the sides and summits, higher up. A few of these details will afford us a glimpse of the wonderful complication of forces that have thrown these mountains into chaos, as well as the tre- mendous power of the eroding agents which have aided to increase the difficulties in some localities and to decrease them in others. As we move westward to the Sawatch range, or the Elk Mountains, we shall meet with a repetition of the same results, only on a far grander scale. South of Horseshoe Mountain the main range continues 12,000 feet and upward to Buffalo Peak, rising far above timber-line. The rocks are mostly granitoid, but'there are remnants of the quartzites even on the crest; but rather low down on the sides, perhaps 1,000 feet below the crest, the Silurian limestones and quartzites crop out here and there, though much obscured by the débris. In the valley of the Little Platte, close to the foot of the mountains, is a considerable thickness of a group of very peculiar gypsiferous strata, the same as those:arotnd the salt- works about twelve miles to the southeast. The surface has a volcanic appearance, as if covered with slag, and yet the clays, sands, and other rocks of both the Cretaceous and Jurassic are incrusted with the chloride of sodium as well as the sulphate of lime. Again, on the HAYDEN.] GEOLOGY—ARKANSAS VALLEY. 47 north and east side of Buffalo Peak the unequal elevation of both the granites and the sedimentary rocks is apparent. They may be seen here in contact at the base of the Peak, or near the summit, 2,000 feet above the base. Twelve-Mile Creek rises near Weston’s Pass, flows for a short distance, about six miles, east of south, then bends so that the course is a little south of east after emerging from the range. The deep gorges are very numerous, and seem to be carved out of the mass- ive granites, presenting on either side remarkable sections. The crest of the divide at the head of the south branch of the Little Platte presents a fine view of the valley of the Arkansas toward the west, with the grand range of the Sawatch on the west side, like a gi- gantic wall, with its wilderness of peaks, upward of 13,000, and many of them over 14,000 feet. Nestled at the base of the Sawateh, at the mouth of the Lake Creek gorge, are the beautiful Twin Lakes, separated from each other by a belt of morainal deposits only about 200 yards wide. To the southeast may be seen distinctly the ranges about the San Luis Valley, with Ouray and Uncompahgré Peaks rising far above all the rest. ‘To the east we have the South Park full in the foreground, look- ing like an immense meadow. ‘The ridges which run across it in differ- ent directions are softened down by thedistance. Pike’s Peak, with the ranges of mountains on either side, shuts oif the vision from the broad. plains beyond; it rises so far above the rest that it becomes a most important landmark for a radius of fifty to eighty miles in every direc- tion. ‘To the northeast and west is the splendid group of peaks of which Mount Lincoln is the crowning one; while to the northwest are the sources of the Arkansas with the Tennessee Pass and its associated ranges of mountains. The Blue River range can be seen dimly beyond. Such are the geographical features of this remarkable region, and I de- seribe them from time to time, to convey to the reader the fact that the variations are kaleidoscopic, and from every important mountain-peak a fresh and equally grand view may be obtained. As I have before stated, it is my belief that the range of mountains on the west side of the South Park is a portion of a grand anticlinal of which the Sawaich range is the central mass or axis. Therefore the general inclination of the great body of the rocks of the Park range is eastward, metamorphic as well as sedimentary. On the east side of the crest the dip of the strata is obvious, and the granitoid nucleus is ex- ‘posed. in comparatively few places, except in the gorges, where the erod- ing forces have cut deep down through the sedimentary beds into the schists. But on the west side the granites are visible everywhere, while the sedimentary rocks are the exception. The action of two forces are indicated in this range; oné which acted uniformly and slow, ele- vating the vast series of North and South ranges from the plains on the east to the Colorado River, and perhaps farther, and a second force operating synchronously, but probably spasmodically, tossing the gran- ites aS well as the sedimentary group into chaos. The one acted in long lines of fracture, forming regular anticlinals with the stratified groups, inclining from either side of the central axis-in regular order ; the latter bringing to the surface the igneous rocks, and producing those wonderful faults of which we find so many illustrations in the Park range. The general form of this range also reveals its anticlinal char- acter, through the fragments of the sedimentary groups which have broken down from the crest on the west side. In the California Gulch, and to some extent in other localities, the igneous rocks have been poured out over the mountain side covering both granitic and sedi- mentary beds, but the granitic rocks predominate, and all others occur 48 GEOLOGICAL SURVEY OF THE TERRITORIES. only in detached portions that seem to illustrate a series of remarkable faults. The Arkansas Valley, from its head in Tennessee Pass to the point where the river cuts through Front range and opens out into the plains, has been worn out of the granite mass to a great extent. The valley is partly a fissure, but is mostly due to erosion. The drain- age was undoubtedly started by the fissures produced by the great up- lift, but, as broad and deep as it is, it is undoubtedly dye mostly to erosion, and by this illustration we may form some conception of the . work of this powerful agent in giving form to the surface of this mount- ain-region. From the crest of the Park range across the Arkansas Valley to the crest of the Sawatch the distance will average from ten to fifteen miles, in a straight line, and the average elevation above the water-level of the Arkansas River must be about 1,500 feet. Now, it is probable that three-fourths of this vast space from the Tennessee Pass to the Poncho Pass, near the head of San Luis Valley, a distance of one hundred miles, has been worn out by erosion, and the greater por- tion of the material carried down the river and distributed over the plains. It is probable, also, that this great space was at no very ancient period filled with one vast glacier, which doubtless performed the greater part of the grinding up of the recks and the wearing out of the valley. - The glacier-worn sides of the mountains on either side of the valley extend- ing nearly to.the summits, the remarkable morainal deposits in the main valley and on the sides of the gorges, point strongly to that conclusion. We hope in the succeeding chapter to describe more in detail the phe- nomena of ancient glacial action, which is so admirably shown on both sides of the Sawatch range. The remarkably rounded and grassy appearance of these high mount- ain-ranges in many instances is quite surprising, and we ask how so great a thickness of superficial earth could have accumulated so far above timber-line? Besides, this drift-like deposit is covered with masses of rock of various sizes, more or less worn, mostly granitic, and mingled with the finer materials are numerous bowlders, so that there must have been some agent that acted quite generally in grinding down the surface. All along the west side of the Park range the granite rocks crop out, but from a point opposite Tennessee Pass to Buffalo Peak this old glacial deposit covers a great portion of the surface. When the underlying or basis rocks do erop out to any extent the ab- rupt side faces west toward the Arkansas, and the gentler slope is toward the east, so that even the granitic nucleus testifies to the anti- clinal character of the range. This is very well shown on the west side of Buffalo Peak, and southward where the granitic rocks rise in high, conical peaks, with the abrupt, wall-like face to the west, and sometimes even overhanging atthe summit. The heavy snows that fall on these mountains, melting in the spring, thoroughly saturate these surface-deposits, and great masses become more or less movable, de- pending upon the steepness of the slope. The degradation of the under- lying rocks is constantly going on,and the movements of the great masses of earth produce results much like those of a glacier. About five miles below the mining town of Granite the upper valley of the Arkansas begins gradually to expand in width. Terraces have been formed on either side, which show the former existence of a lake. It is most probable that the lake-waters set high up the Arkansas River, even to its source; but the greater portion of the waters were gathered into the lower part. By Upper and Lower Arkansas I mean the portions above or below the cation. In the lower portion of the Upper Arkan- * ot GLEE in aE eae f YY Vids iitae tee = a = a a4 / 7 Yf = an i YY, cs ee a ot Ui — AES ws SVS East side, granite anticlinal, Upper Arkansas Valley. HAYDEN.) GEOLOGY—SAWATCH RANGE. 49 sas I described, in my third annual report, for 1869, a group of light- colored marls, 800 to 1,200 feet in thickness, under the name of Arkan- sas marls. I then regarded them as of Pliocene age, and noted their inclination as 3° to 5°, which would imply that they were deposited be- fore the great Sawatch range had reached its present height. Itis plain that at a period comparatively modern in date there was a lake here at least forty or fifty miles in length, and from five to ten in breadth, and that in the Jower portions several hundred feet in thickness of fine sediment were deposited in moderately quiet waters. The numerous lit- tle streams that flow from the Sawatch range toward the Arkansas cut deep channels through this modern deposit. .The quantity of rounded bowlders of various sizes in the vicinity of these streams is immense. Even after the lake-waters had passed down the Lower Arkansas, through the cafion, there must have been tremendous glacial as well as aqueous forces operating from the deep gorges in the mountains, transporting a vast amount of drift material into the valley. Just how much of this broad expansion is due to erosion it is difficult to determine, but I am inclined to the belief that there was originally only the fracture of elevation, and that the old lake-basin is mainly due to erosion. On neither side of the valley do we see any of the older sedimentary rocks. From Poncho Pass to the very source of the ArkanSas, a distance of 80 miles, no rocks but Igneous and Metamorphic can ‘be seen upon the east side. The Sawatch range is one solid mass of granite, intersected to a greater or less extent by dikes. If we follow any of the little streams that flow from the range on the east side, up to the sources of Trout Creek, for example, just before reaching the borders of the South Park, we shall find the full series of the sedimentary rocks, from the Silurian, resting on the granites, up to the Cretaceous, inclusive, at least, inclining in an easterly direction. The tendency of the waters of the Arkansas River was to gravitate to the extreme eastern side of the valley, from the slope given by theanticlinal character of the elevation. The abrupt- ness of the east side of the granite rocks on the east side of the valley, from one end to the other, shows the part which they sustained in the uplift. From a point about two miles below the mouth of Pine Creek the Arkansas River flows through a very narrow, tortuous channel, with the granite rocks of a great variety of texture projecting over the base in some instances, and rising in a precipitous wall a thousand feet high. Below the mouth of Trout Creek the eastern portion of the anticlinal becomes the Front range. I have dwelt solong on this great anticlinal because it constitutes the key to the physical structure of a great area, and also because it will throw much light on other portions of the Rocky Mountain region. It seems to illustrate a statement that I have often made, in previous reports, in regard to the simplicity of the structure of the eastern portion of the Rocky Mountain region. In general terms, while the details are extremely complicated, we may express the structure of a belt of country known as the Sawatch range, eighty miles in length from north to south, and at least forty from east to west, as a single wedge of granite, thrust upward, and the sediment- ary rocks inclining from either side. The illustration of which the Sawatch range is the central mass is probably on a'grander scale than any other in the West, but there are abundant examples of smaller size. The Black Hills of Dakota, the Laramie range, Big Horn, Wind River, and many others are of the same type. Our last movement, July 22, was along the divide from Weston’s Pass to the base of Buffalo Peak. We have described the splendid view we obtained of the entire Upper Arkansas Valley, from the Ten- 4658 50 GEOLOGICAL SURVEY OF THE TERRITORIES. nessee Pass to the cation, a distance of eighty miles. Our camp was on the north base of the peak, above timber-line, at the very sources of some of the little branches of the Platte. The granite rocks cropped out all around us, although the greater portion of the surface was covered with grass, and the moist valleys were peculiarly fresh and green. The lower portion of the Upper Arkansas Valley is indeed a park, and far more beautiful, though not so large as the South Park; but its origin is very different. The South Park is an area of depression, that is, it is a basin surrounded by lofty ranges of mountains, underlaid with rocks of the sedimentary group, which shows that it has never been elevated equally with the surrounding mountainwranges. The Ar- kansas Park is an area of upheaval and erosion, and nowhere in it are any sedimentary rocks exposed older than the modern lake-deposits. A few small streams flow into the Arkansas River from the east side, but the main drainage is from the west side. Descending into the val- ley on the west side of the Park range, from the base of the Buffalo Peaks, we found the traveling very difficult; the sides of the mountaing covered with débris and very precipitous. The fallen timber adds also much to the labor of traveling. The autumnal fires sweep over the sides of the mountains, killing the pines, and the winter and spring winds lay them down in every direction, forming a pertect net-work. Reaching the valley nearly opposite Mount Harvard, we camped for two days on the bottom to make a study of this interesting region. By following our route of travel in our narrative, we are enabled to note down the local details of the geology from point to point, on which any general remarks we may make are founded. The maps, which will soon be published, will enable the geological reader to follow these routes with ease; and, in connection with the sketches and sections, we hope to make our observations clear. The point from which we will start now on our march up the Arkan- sas River is at the head-of the Arkansas Park, a little below the mouth of Pine Creek. The valley here begins to expand out somewhat, and is about half a mile in width. There are several abandoned farms on the bottom. Lower down in the main park, or valley, are some excellent farms and prosperous settlements. The decline of the mining interest has caused the upper portion of the valley to be almost entirely deserted. A few years ago there were many thousands of miners in the valley, and every gulch was filled with placer-diggings. Granite bid fair to become a city and spread itself over a considerable area on both sides of the mines. Now the buildings are all fast going to decay. A few miners still linger among the old “ placers,” but the mining period has passed away. I have spoken of the finer sediments which were deposited in the ancient lake, in the lower portion of the valley to the southward. The waters that rushed down from the north lost the greater part of their force in the broader, deeper waters of the southern portion. Here the fine material which was ground from the granite rocks by water and ice to the northward was carried, and the greater stillness of the waters then allowed it to settle on the bottom more quietly, forming a group of marly strata at least 1,200 feet in thickness, which have weathered into the peculiar architectural forms which characterize the modern lake- deposits farther north in which the remains of so many extinct verte- brate animals have been found. As we ascend the valley from the lower end, these lake-deposits become coarser and show evidences of deposition in more turbulent waters, until at the upper end the huge rounded bowlders predominate. Near the bridge about five miles below Granite are long, lone ridges of the coarse drift or detrital matter on ‘opeiopog ‘eyeryT uray, roddy) (hy i ly He mL 9 WES SH i Ii Sah SS Y Hl | i lf | | iF t f Wik ) x! AS aes AN a wi WN d RY Ve fst STM KES? 7 ‘OL SA AYDEN.] GEOLOGY—SAWATCH RANGE. 51 the bottom, parallel with the river. The surface is covered with huge granite bowlders on both sides of the river; long, high, rounded ridges of worn bowlders are pileu up as if they had been left by the melting masses of ice. We find the granite rocks in place much wornas we ascend the valley, but no signs of grooving. The coarse texture of the granite permits them to disintegrate readily, and they have a tendency to become rounded by a process which I have termed exfoliation, or a tendency to peel off in thin concentric layers. This isa very common feature in most of the varieties of rock in the West, and the great variety of scenic forms, as well as much of the loose débris or soil in the mountains, is due to this process. Whenever the fires run over the sides of the mountains, burning the forests of pine, the most compact granite rocks scale off in this manner, and undoubtedly the sun’s rays, expanding the surface by the heat, produce similar results. Just below the mouth of Pine Creek a high vertical point juts out from the east side of the Arkansas, over the river, of a harder texture and more compact than the contiguous rocks. The jointage, which is nearly vertical, presents strikingly smooth faces and sharp angles. The great variety of texture in the granitic rocks is con- tinually shown, varying from a close fine-grained feldspathic or quartz- itic mass, scarcely affected by atmospheric agents, to a very coarse ag- eregate, readily falling in pieces. Iron in some forms is a very powerful agent also in destroying the cohesion of granites. This hard point seems also to have extended across the river and to have resisted in part its power, so that falis, or rapids, of 25 feet descent have been formed. Just above this point there is a low ridge of granite, which in the wearing out of the valley escaped, while on the east side of the Arkansas there is an old river-bed. These remnants serve to indicate in some degree the nature and extent of the forces that have operated here. They prove that the valley is, for the most part at least, one of erosion. There is a narrow bottom on the west side of the river, with small guiches coming from the hills in which are quite extensive placer-diggings. Small log huts, or miners’ cabins, are scattered here and there among the huge granite bowlders, presenting a unique appearance from their diminutive size, compared with the bowlders themselves. Perhaps the most interesting and novel features of this region are the ereat morainal deposits, the remains of ancient glaciers. These proofs of glacial action occur everywhere along both the east and west sides of the great Sawatch or Mother range. But up the valleys of some of the side streams the morainal deposits are more marked and regular than in others. The finest illustration occurs in the valley of Clear Creek, a small stream that flows into the Arkansas River from the Sawatch range, about six or seven mills below Lake Creek. This little stream rises high up near the crest of the range, in a number of exca- vated amphitheaters, and flows for several miles through a close canon until it opens out into the foot-hills on the east side of the range. The valley at once expands to about one-fourth of a mile in width, and at the junction of the creek with the main river has become three-fourths of a mile in width, with a detrital ridge on either side rising 300 to 500 feet above the little creek that meanders through it. These detrital ridges show the loose character of the deposits by their rounded forms, being covered over with grass and other vegetation. The question would arise, whether the immediate valley of the stream was originally filled up with the glacial detritus, or whether the mater- ials composing these ridges were left on the sides of this branch of the great Arkansas glacier which must at one time have occupied the entire valley. I am inclined to think that the valley through 52 GEOLOGICAL SURVEY OF THE TERRITORIES. which Clear Creek meanders so beautifully is a modern result, and was worn out of the great detritul mass by water after the close of the true Glaeial period. Between the detrital walls in the valley are mounds or ridges of the detritus that has been brought down Clear Creek and lodged near its mouth. The last glacial movement was checked by the remnant of the granite mountain in place at the lower end of the ex- pansion, and as the ice melted the débris was left behind in irregular mounds. Rounded masses of granite of immense size, 100 feet in diameter lie scattered about: the mouth of this creek, now going to decay by the process of exfoliation. Between Clear Creek and Lake Creek the slopes are rather smooth, with the granite rocks cropping out here and there, but revealing the effects of abrasion in a marked degree. The surface is covered mostly with a thick deposit of the detrital mat- ter. The placer-mines are very extensive over this area, and the work- ing of them in several localities has exposed a glimpse of the old chan- nels worn deep into the underlying granites and covered with the bowlder-drift. If this thick drift-deposit could be stripped off it would expose a granitic surface worn down by the movements of vast masses of ice and snow, perhaps grooved and scratched, and the entire area cut through from the mountains on either side with the old creek-chan- nels. We believe, also, that this space between the main river and the base of the range, a width of about six miles, has been worn down from an elevation but little, if any, lower than the front portions of the range that now remain. Alithe evidence points to the existence here of aqueous forces at a comparatively modern period, of which the present is but an insignificant remnant. f On both sides of the Arkansas up to its very sources the drift phe- nomena are very remarkable, but much more extensive on the west side, so that there is a slopefrom the immediate base of the Sawatch range to the river; but the terraces and bowlder-deposits are well shown on both sides. On the west side the valleys of the mountain-streams are - now much used for the pasturage of large herds of stock during the summer-season, the owners driving them south into the San Luis Val- ley during the winter. By glancing at the map it will be seen that there are a considerable number of those little branches which run high up near the crest or water-divide of the Sawatch, cutting deep channels or gorges through the mountain-sides, and deep valleys after emerging into the slope, or foot-hills. The slope, or foot-hill, forms a peculiar belt from four to six miles in width between the base of the main range and the river, and in a general way slopes down to the river. The difference in elevation between the bed of the Arkansas and the junction of the slope with the mountain-side would vary somewhat, but must be 1,000 to 1,500 feet. Viewing this slope from the crest of the Park range on the opposite side of the Arkansas we can see clearly the gorges and gorge-like walis of the principal streams at intervals of a few miles apart. Be- tween the main valleys the interval is singularly rolling, consisting of rather deep grassy valleys, extending down from the mountain-sides to the Arkansas, while between them are rounded ridges, or rounded oblong hills, covered over with débris. In many cases the abrupt sides are toward the mountains, and the sides and summits are covered with immense bowlders, as if the masses of ice had lodged on them, and melting had dropped their contents there. This furrowed condi- tion of the surface continues to a greater or less extent up to the sources of the Arkansas in the Tennessee Pass. The great morainal ridges on the south side of Lake Creek are as much as 500 feet to 700 feet high of TWIN LAKES Showing adjacent MorAINES ARKANSAS VALLEY, Prom Reconnoissance Survey By Henry Gannett. ale, SAI ete ASS SD Soundings in Leet. se LAD) . a eee ae ot eee at i oa j Oa, i | at | HAYDEN.] GEOLOGY—SAWATCH RANGE. 53 above the lakes or valley. For about fifteen miles the Arkansas flows through a gorge-like channel, commencing about four miles above Lake Creek, when there is a moderate expansion with quite a broad bottom, and on either side well-defined terraces. The terrace on the east side of the Arkansas rises about 500 feet above the river-bed. In a dry gulch the horizontal strata of sandstone crop out, showing that it is composed of the modern lake-deposit. On the west side the first ter- race rises 40 feet, the lower portions of the second or main terrace 250 feet rising up, by a slope to the mountains, to the height of 700 feet. One gulch is quite wide, half a mile, as it opens into the valley of the Arkan- sas, with small, terrace-like steps on either side. The east fork of the Arkansas also presents a broad, open valley for some distance along its junction with the main stream. Passing up the west branch we find a broad, open, meadow-like park, a mile in width, with the granitoid rocks cropping out here and there on either side from beneath the great accu- mulation of detrital deposits. We can see, therefore, that this entire valley of the Upper Arkansas was at no very remote geological period, a fresh-water lake, probably at the close of the glacial period. Iam now inclined to think that this period extended back further into the past in the Rocky Mountains than geologists have accredited it in other regions. It seems to me that the evidence, though not clear as yet, points to the Pliocene era as its begin- ning, at least, and that it extended pretty well toward the present period. It was evidently a period in which powerful forces were in operation, which carved out the surface-forms much as we find them at the present time. CHAPTER III. SAWATCH RANGE—MORAINAL DEPOSITS OF TAYLOR’S CREEK—ELK MOUNTAINS, ETC. We will now ascend the valley of Lake Creek, and wend our way over the great Sawatch range. The valley of Lake Creek is filled with the morainal deposits for which this range is so remarkable. It would seem that the great glacial force moved here in a direction a little south of east, inasmuch as the great mass of the detrital matter is heaped up on the south side. The two lakes are about 350 yards apart, with a small stream, perhaps 20 feet wide, flowing from one to the other. The interval is made, up of worn detrital matter, but over it and around both lakes are mounds or oblong ridges of the drift. Scattered over the surface are masses of granite, coarse in texture, with crystals of feldspar, 1 and 2 inches in dimensions, aggregated to- gether. The rock has the appearance of a feldspathic breccia. The lower lake is about two and.a half miles in length, and one and a half miles in width. The upper lake is one mile in length, and half a mile in width. The bases of both these lakes are undoubtedly the result of giacial action. The greatest depth found by sound- ing was 76 feet. The accompanying topographical sketch of Mr. Gannett, with the soundings which were made by Messrs. Stevenson and Holmes, will convey a true idea of the form of these basins. We know by the land contiguous to both these lakes that they have been Slowly diminishing in area. Above the Upper Twin Lake there is a half- mnile in width of boggy meadow which at no distant period must have been covered by the lake. At the head of the valley, or where the 54 GEOLOGICAL SURVEY OF THE TERRITORIES. gorge begins, there is a sort of natural bridge. ‘The stream has: worn a narrow channel through the rocks. At the summit the gorge is about 8 feet wide, and in it a huge bowlder has lodged. The stream rushes down its steep, narrow, winding channel with great force. On the north side there is a huge bowlder just ready to topple off into the channel, which is 50 feet in diameter. On the sides of the channel are several most remarkable rounded cavities worn in like pot-holes, 6 to 10 feet in diameter. One of them occurs 20 feet. above the water-level of the creek at the present time. About 100 feet above the bridge the stream flows through a narrow gorge not over 4 feet wide, and the water shoots down asin a flume 10 or 15 feet, producing a picturesque effect. In these rocks the jointage is very distinctly defined. The dip of the rock is north about 30°, and the channel has been worn through the rock, so that the north side over- hangs the water, and the water and ice, aided by the jointage, have removed masses like blocks from a quarry. There are two or three sets of master-joints which break the mass into a multiplicity of forms. Sometimes the broken portions are wedge-shaped. The rocks are a coarse, massive granite of a gray color, with large crystals of grayish- white feldspar. The worn rocks, or roches moutonnes, are most admira- bly shown everywhere, and portions crop out in the bottom of the val- ley to indicate the force as well at the extent of the erosion. It is quite possible that if all the débris could be stripped off the gorge and valley, the grooved or scratched surfaces would be apparent. On both sides of the gorge the worn rocks are seen to the height of 1,000 to 1,500 feet above the bed of the stream. One immense mountain mass on the north side seems to have resisted the eroding forces, so that from base to summit, a height of 1,000 feet, it is smooth like enamel. The vast gla- cier which must have filled up the channel must have been obstructed in its slow downward movement by this projecting point of the mountain. — In the side near the base are quite deep, rounded cavities, 2 to 4 feet in diameter, produced by the same causes as the pot-holes. About2 miles above the falls there is an extensive dike of trachyte. It occurs in the form of a vein, 6 to 10 feet wide, running about northeast and south- west. There are many other dikes in this gorge, of different sizes, and I suspect some of them would prove to belong to different ages if more closely studied. The great branch-glacier of Lake Creek must have been 1,500 feet or more in thickness. The valley or gorge is nearly uniform in width, about one-fourth of a mile, and the glacier must have plowed its way along, paring off a great thickness of the gneissie rocks on either side and on the bottom, the low, rounded remnants of which can be seen cropping everywhere from the detritus. The sides of the gorge for 1,000 to 1,500 feet are worn smoothly, and in some places immense blocks of granite have been wrenched from their places and carried down the channel, so that the sides look like a quarry. The most striking feature is the very smooth surface of the sides of the gorge to so great a height, like glass. About six miles above Twin Lakes, in a straight line, Lake Creek forks, one branch extending up northwest, and the other southwest. Both separate again soon into a number of smaller branches, which end in amphitheaters near the crest. About four miles up the North Fork a remnant of the gneissic rocks, left in the wearing out of the valley, has a dip of 50° NW., with a strike southwest and northeast. There are a number of these low ridges rising up in various portions of the valley, showing most clearly that the entire gorge has been carved out of the mountain mass. The dip of the beds would indicate a fracture for the water and ice to commence their oan] GEOLOGY—MORAINAL DEPOSITS. 55 work, and, as the gorge increased in size, the power to excavate would be increased. The crest of the range is covered with trachyte for miles, and: from that ridge extend down beautiful green valleys above timber-line. The sides as well as the circular end of these gorges or valleys are cov- ered with débris composed of the broken fragments of igneous or meta- morphic rocks. All seem to originate in the same manner, and are con- tinued by the same forces. The igneous rocks seem to have flowed out over the gneissic rocks to a considerable extent, at least 500 feet in thickness, as is shown in this high mountain-valley, where the sides are nearly vertical, and the bottom of the Yalley here and there reveals the granitic rocks upon which the trachytes rest. So, we have in the main range the same phenomena repeated that we find in all the southern ranges, viz: a granitic nucleus or central mass, with dikes of igneous rocks to a greater or less extent. The movements that elevated these great ranges seem to have generated the heat that reduced the rocks in certain portions of the crust toa fluid condition, and they came to the surface in almost numberless places. We will not now discuss the history of the glacial period of the Rocky Mountains, but simply state, in general terms, that the evidence seems to point to a time when the Arkansas Valley was filled with one enor- mous glacier, and that extending from it, on either side of the gulches, were branches of greater or less magnitude; that as the temperature changed so that it was gradually reduced, and the physical conditions approached those of the present time, the basins of the lakes were scooped out, the morainal detritus was deposited, and finally the im- mense granite bowlders were scattered over the surface. We shall endeavor to show in a subsequent chapter that this glacial pericd was one of great length, and that the gradual transition from the extreme glacial cold to the present climatic conditions was of great duration, and influenced the sculpturing of the surface to a very great extent. Our trail over the mountains led up the south branch of Lake Creek. In many instances, these little branches have cut narrow channels into the solid rock 30 feet in depth. This must have been done subsequently to the meiting away of the glaciers. About four miles up the valley the débris begins to be made up of igneous rocks that have fallen down from the high ridges. There are, also, immense masses of voleanic breccia, very compact, composed mostly of granitic fragments of various sizes, some worn and others angular. We see again the high crests capped with the igneous rocks, which originally flowed from fissures in the granite, and, as the liquid rock was ejected, fragments of the contiguous granitic rocks were worn off and inclosed. This fork also branches off to the north toward Red Rock Pass, and the usual signs of the wearing out of these vast mount- ain amphitheaters can be seen. The valley, or gorge, here is unusu- ally broad, and yet the abrupt walls on either side show its origin. The ridges are all capped with the igneous rocks, and, in some instances, they are a brilliant red. The gorge is cut deep down into the granitic rock, and, when it is not concealed by detrital matter in the bottom of the valley, is worn smooth. We ascend the steep sides of the divide between the waters of the Pacific and those of the Atlantic, by way of Lake Creek Pass. The melting of the snow keeps the sides of the mountain, where covered with loose earth, in a boggy condition, which impedes traveling. Upon the summit of the pass is a little lake or reservoir for the water from the melting snows. On both sides are high walls about a fourth of a mnile apart, between which is located the pass. It is not so very muck -56 GEOLOGICAL SURVEY OF THE TERRITORIES. lower than the crests around, being over 12,000 feet above sea-level, and 2,000 feet above our camp at the forks. But the pass itself is an illus- tration of the slow wearing away of the crest between the sources of ‘the streams. The summit of the pass is very narrow, and on the top and sides are vast quantities of fragments of rocks fallen from the side- walls. There is no doubt in my mind that the crest of the mountain was at one time continuous, and far greater than at present, and that a mass of granite rock the width of the pass, and 500 to 800 feet high, ‘has been removed by agencies not now in operation. Yet the-slow pro- seess of the breaking down of the sides still goes on summer and winter, cand the débris forms one of the remarkable features of this region. As we descend the west side of the pass, we have before as in full view one of the most spacious and regular amphitheaters we have seen, form- ing the source of Morainal Creek. It is in the form of a semicircle, with an irregular wall around forming the mountain-crest. On the west side are two mountain-cones rising up 13,000 feet or upward; on the east side, a high rounded peak covered over with débris, while the south side has been broken down so as not to be more thap 300 feet above the base of the wall. Vast quantities of the débris, or talus, lie all around the base of the wall, while in the center is a forest of pines. We see, therefore, that although the evidence is clear that these amphi- theaters have been carved out of the massive granite, no forces are now in operation to carry away the fragments of rock that are annually loosened from the walls by water and ice, but they gather on the slope, forming a talus of great magnitude. We shall have much to say, as we pass from point to point, in regard to mountain sculpture. We believe that geologists have hardly realized as yet the tremendous degradation of our high mountain-ranges, which has been carried on during, or since, the Tertiary period. i We descend to the west side of the mountain to the little creek, and find ourselves in the midst of the most striking examples of morainal ridges yet seen in the West. These extend from a point near timber- line down to the valley of Taylor’s Creek, a beautiful stream that oceu- pies in part a valley parallel with the Arkansas on the west side of the main range. I have spoken previously of the anticlinal structure of this region. On the west side of the Sawatch or Mother range there is an irregular parallel depression, extending northward to the Mount of the Holy Cross, and southward far down the Gunnison Valley. Yet the drainage is not continuous north and south like that of the Arkansas. The drainage tends toward the northwest in the valleys of Roaring Fork and Frying-pan Creek, and to the southwest in the valley of Gun- nison and its branches. While between the waters of the two systems the divides are quite high and almost impassable, still the inclination of the great mass of the rocks is toward the west in general terms, and the anticlinal. structure well illustrated. The interval between the ridges is much more broken, and has not been worn out by one con- tinuous river like the Arkansas. The morainal deposits are best shown on the west side of the Sawatch range. Along the side of the mountains, rising 800 to 1,000 feet above the valley of Taylor’s Creek, is a ridge entirely covered with the débris falling from the summits of the range, and mo- rainal matter. It is most probable that the granite rocks form the nucleus, but that the ridge has been worn down:by glacial action and e;vered over with the miscellaneous deposits of morainal drift. The ridge is quite rounded in form, covered in many places with pines, and extending up on the sides of the range nearly to timber-line. The second HAYDEN. | GEOLOGY—MORAINAL DEPOSITS. 57 terrace, aS it may be called, is very irregular, varying from 20 to 80 or 100 feet above the valley, and is full of irregular depressions like small lake-basins, but without any apparent outlet. Fragments of glaciers must have remained in this place which melting away, formed reservoirs of water, which finally dried up, the morainal matter accumulating all aroundthem. Sometimes these depressions are oblong and tortuous like the old bed of a stream, and continue for a mile or so, and then close up in a sort of pocket. The surface is covered all over with worn bowlders of granite of various sizes, sometimes 20 or 30 feet in diameter. When streams have cut through it so that sections can be seen, which is not common, it appears to be composed of rather fine earth, evidently the result of the grinding of the granite rocks by ice,and more or less rounded granitic masses of all sizes from a small pebble to a mass of many tons’ weight. The position of the morainal deposits would indi- cate that on the west side of the range also there was, during the glacial period, a vast mass of snow and ice filling up the open valley and run- ning up tke gorge like valleys on either side. The valley of Taylor’s Creek, which will average a mile in width, is covered over with isolated morainal mounds or ridges, never more than 50 feet high. The enor- mous accumulation of the morainal matter on the west side of the range would seem to show that the great body of the glacier was there, though extending far westward are abundant signs of glacial action. | We shall speak of this subject again in describing the Mount of the Holy Cross and its surroundings. Far to the south, looking down the broad, open valley of the Gunnison River, we can see the modern lake- deposits much eroded near the junction with the Grand River. Still farther southward is the Uncompaghre range dimly seen on the horizon. To the west is a portion of the Elk range, with the wonderful mass of red rock and the great group of sharp peaks, which show a remarkable chaos of strata. To the northwest are the sources of the Gunnison, with the rounded, granite mountains which have been so distinctly glaciated. Here and there the stratified rocks may be seen resting on the granites, and inclining at different angles. To the north is a wilderness of peaks, which form the Sawatch range, some capped with igneous rocks, others projecting their ragged, sharp, granitic points or crests high up among the snows, 14,000 feet and upward. The quite irregular ranges of mountains on the west side of the Gunnison show most clearly that they are subordinate portions of the great anticlinal we have been describing. The abrupt side or face is toward the east, while on the west side the slopes are usually gentle, and whenever the sedimentary beds occur they incline toward the west. The basis rock of the Gunnison Valley, under- neath the great thickness of morainal detritus, is granitic, resembling very closely the granite rocks of Sait Lake Valley, Utah. The gray granitic rocks are full of black, apparently rounded masses, as seen in Cottonwood Cafion, which indicates that they were originally conglom- erates, so changed by metamorphosis that only indistinct traces of the included bowlders are now visible. The irregular range west of the Sawatch is undoubtedly, as I have before stated, a subordinate portion of the anticlinal on the west side. Fragments of the great mass of sedimentary rocks can be found at differ- ent elevations, especially on the west side, though the granite rocks pre- dominate. About four miles up one of the small side-valleys of Taylor’s Creek, to the west, we find low down in the bottom a patch of massive dark-blue carboniferous limestone with corals and stems of crinoids. Some of the layers are made up of fragments of organic forms. The whole is about 50 feet in thickness, inclining west 12°. It is simply a 58 GEOLOGICAL SURVEY OF THE TERRITORIES. remnant of the great mass that once extended over the country from the plains across the South Park, the Park range, Sawatch, &c., inter- rupted, perhaps, here and there. We have already observed that the Carboniferous as well as Silurian beds are omitted for one hundred and fifty miles along the east margin of the mountains north of Colorado Springs, while far north and far south the same rocks are well developed in similar localities. So we may make the general statement that these beds covered all this great area prior to the elevation of the ranges. AS we proceed westward from Taylor’s River, we enter a region in which the rocks have been thrown into a ereater state of chaos than I have ever observed anywhere in the West. There is no doubt that the original inclination was toward the west from the Sawatch range, but the great number of dikes that intersect the crust in many places, have tipped the stratified rocks in every direction, elevated them to the sum- mits of the peaks, and, in many instances, completely reversed their position, so that we have the oldest rocks overlying those of more mod- ern date. It is not uncommon to see ridges of quartzite, or limestone, standing vertical, and, in some instances, inclining several degrees past a vertical. To solve all these problems well would require that every portion of the country should be studied foot by foot, and hundreds of detailed sections prepared. Our plans would not admit of this detail, and, therefore, much must remain obscure until we can gain the time to make special studies of the more difficult localities. Besides, we need better maps, which are now in an advanced state of preparation. It is plain, however, that the sedimentary beds are essentially the same as those of the Park range, and that they have been subjected to greater overturnings than those of that range. ‘There is at the base, and resting on the granites, a great thickness, perhaps in the ageregate 2,000 feet, of quartzites and limestone in alternate strata. Above these is a great thickness of limestones of a more modern aspect, with well-known Carboniferous fossils in them, and in some localities very abundant and well preserved. Above these comes a vast group of red sandstones assuming a great variety of textures, as well as shades of color, at different points. Above come in regular order the Jurassic and Cretaceous groups. In this district of chaotic overturnings we saw no rocks of more modern age than the Cretaceous, though it is quite probable that a more extended exploration would have discovered them. The main streams that flow toward the west have cut deep gorges directly through the uplifted ridges, as well as dikes, while the side branches have formed in many instances parallel valleys. In all cases the amount of detrital matter is very great. Huge masses of granite are strewn over the surface, sometimes in the valleys and some- times on the sides of the hills or mountains. The peak named on the map as Italian Peak, 13,255 feet in height, is an example of the varie- gated colors of the rocks, due to the flowing upward through the fissures of the melted rocks, accompanied with a force that tilted the sedimen- tary strata in all directions. Leaving the valley of the Gunnison, we took a southwest course, up a nearly dry, rather broad, grassy valley, to the divide, and descended again to West Taylor Creek. These little side-valleys occasionally close up for a short distance in a sort of gulch or canon, then suddenly expand out into an open oval one, covered with thick grass like a meadow. This is a very commen form in these mountain-districts, es- pecially where the granites prevail. Soon after passing the divide we find the sedimentary rocks cropping out everywhere. In the valleys there is a great amount of the superficial drift, forming rounded hills or ACE] GEOLOGY—MORAINAL DEPOSITS, 59 long ridges, the surface being covered over with fragments of limestone, sandstone, and pudding-stone. About four miles below the divide the little stream cuts through a high ridge. On the south side the ridge is composed largely of laminated trachyte, inclining to the northwest at an angle of 60°. While on the north side the rock is more compact, hard, and full of masses of quartz, as if the old granite had been tur ned to a somber gray by the heat of the igneous rocks; this mass, which is very conspicuous and rises 800 feet or more above ‘the little stream, ap- pears very distinctly stratified, and inclines 60° northeast, while the limestone-beds dip northwest 30° to 60°. This is a most complicated piece of geological work, which would require more time than any of the party could devote to it to work it out in detail, though the report of Dr. Pealeis more complete. We believe that the igneous rocks have been pushed up from beneath the overlying quartzites and limestones in the form of dikes, along a line trending about northeast and south- west. The peculiar bedding of the trachyte is so regular that it gives them strikingly the appearance of stratified rocks. There are several ridges nearly parallel which present somewhat the form of an anticlinal, the felstone ‘porphyries being lifted up so that they present their basset edges opposite the outcropping edges of the limestone and quartzites ; thus one side of the anticlinal is composed of igneous rocks, and the opposite side of sedimentary. Between the porphyritic rocks and the limestones there is quite a wide interval, 400 or 500 feet, worn out by the action of water, and covered with debris, but underneath are the up- turned edges of qnartzites, pudding-stones, and sandstones. The strike of the limestones is about southeast, with a dip northwest 60°. The limestones are 150 feet thick, and filled with corals, Productus, and other forms, which indicate Carboniferous age; the whole standing up likea massive wall 300 feet high. On the outer side of the wall comes 400 or 500 feet of soft sand, reddish-yellow and brown, with some harder lay- ers of sandstone, inclining at the same angle, but worn down low, and covered with grass. Then comes another bed of trachyte, with the layers forming a synclinal with the Carboniferous limestones. Between the two trachytic ridges deep side-gorges are worn down to the stream that has cut its channel through all the ridges at right angles. About two miles farther, near the junction of the little stream that flows from the foot of Italian Peak, on the east side, the reddish sandstones occur with layers of a coarse conglomerate, made up of well-worn pebbles of limestone and quartzites, much like the conglomerate seen near Mount Garfield, in Montana. I think there is here an example of a great fault, where the old Silurian quartzites and limestones have been lifted by a force acting vertically, so that the strata are horizontal, while the younger beds, Carboniferous and Triassic, are inclined from the west side at an angle 60° to 80°. The valley is full of detrital matter, and at _ one point the stream cuts through a sort of moraine, showing a section of 60 feet on either side composed of gravel and huge bowlders much worn, while high up on the sides of the hills bordering the valley this drift conceals to a great extent the basis-rocks. The rather rounded wooded ridge on the west side of the branch is covered with the débris of the trachyte, which shows that the dikes penetrated the crust everywhere. The sedimentary rocks crop out here and there, so that we can infer their existence. Sometimes only the quartzites are left, and the igneous material has been poured over them: again, on the Carboniferous limestones, or the red sandstones of the Triassic, or even the black clays of the Cretaceous. All these formations crop out from beneath the trachytes in the vicinity. 60 GEOLOGICAL SURVEY OF THE TERRITORIES. We passed up the valley of a small stream that flows southward from Italian Peak. This peak is literally filled with dikes, which have so changed the contiguous rocks that they present a great variety of struc- ture and color, and hence the name. Indeed, the peak itself is the result of pressure of the igneous matter from beneath. On the north- east side the great mass has been pushed up 1,500 feet, so that on the south side the unchanged quartzites, rusty brown and gray, stand vertical, and in some instances 35° past a vertical. The stratified quartzites are full of seams of crystalline quartz with what appears to be silver ore. The upthrust of the igneous rock has produced great chaos in the beds. Above this locality on the peak there is a fault in which the entire group of Silurian strata is thrown off from the dike so that one portion is separated from another and is lifted up vertically 1,000 feet above the original point of junction. In this district of igneous uplifts the faults are very numerons and striking. Thrust in between the strata are irregular layers of the trachyte, varying from a foot to several feet in thickness, and extending horizontally sometimes several hundred feet, thinning out at each end. One of these intrusions ex- panded to a thickness of 40 feet on the east side of the peak. From this peak we have a most remarkably extended view on every side. To the southis the East Fork of the Gunnison with the red and yellow beds in the foreground, and far distant the older rocks are thrown up at various elevations, apparently local uplifts. To the west is a vast group of sharp, jagged peaks and crests, saw-like, with stratified cone-shaped pyramids; some red, others dark ashen-brown, or maroon-color. All the rocks, as far as the eye can reach, appear to be stratified, though inclining in various directions. The general level of the summits of the peaks is upward of 15,000 and perhaps 14,000 feet. To the east we see with great distinctness the valley of Upper Gunnison with the Sawatch range beyond, and on the west of the range the ridges of stratified rocks in- clining from it. These extended views from the summits of the highest peaks enable us to generalize to some extent the local details that we have already worked out. We see thousands of feet in thickness of stratified rocks, tilted in every direction by a great number of local up- thrusts of the igneous rocks, so that we see strata of different ages some- times on the summits of the highest peaks, over 14,000 feet above the sea. And again, in the lowest valleys we have a thick group of Silurian strata, quartzites and. limestones, then above them a group of Carbon- iferous beds, then the red or Triassic, and in some instances the Cre- taceous; but the latter are seldom seen on the high mountain-ranges. AS near as we could estimate, there are near this peak 2,000 feet or more -of Silurian quartzites and impure limestones; 1,500 to 2,000 feet of lime- stones and shales of Carboniferous age. From the Italian Peak we descended the valley of the little stream that flows from its south base and runs southward into a branch of the - Gunnison. On the west side of the valley, or gorge, a wall of quartz- ites rises up nearly vertical 2,000 feet. This valley presents an example of a synclinal in which the shales are most chaotically crushed together. The quartzites incline from each side of the valley or gorge. Dikes of trachyte pass across the strata from east to west, sometimes disturb- ing the beds so that they incline north and south, and again the dikes are seen without any disturbance of the contiguous rocks. Quite abun- dant fossils were found in the Carboniferous limestones; among them Athyrus subtilita, Productus, corals, crinoids, &e. AS we continue toward the west the red or Triassic beds in full devel- opment cover the surface as far as the eye can reach, interrupted only Gothic Mountain, Elk Range. Fig. 13. = — —= = Italian Mountain. AERC eee vu taht (he * a GEOLOGY—MORAINAL DEPOSITS. 61 in restricted localities by the outflow of igneous matter. Between East Fork and the next branch a long ridge runs nearly west down toward the Gunnison 1,200 to 1,500 feet above the stream. On the north side of the valley of the east branch the dip is variable from 10° to 30°, and trending toward the west and northwest. There is really here a broad slope extending from Italian Peak to Teocolli, where the little streams have carved out deep gorges through the red sandstones and pudding-stones. The aggregate thickness here cannot be less than 2,500 feet, and it may be much more. The valleys or gorges have all been formed by erosion, and from margin to margin they are usually about a mile in width, sloping down more or less abruptly to the bottom, where the immediate valley varies from 100 yards to one-fourth of a mile in width. The texture of these red beds is very variable. Conglomerates vary- ing from a fine pudding-stone to a coarse aggregate occur all through the mass, but are not continuous. The entire group indicates deposition in disturbed waters. In tracing a bed horizontally sometimes it will thicken to a massive fine sandstone, then gradually thin out, and in its place: soft, yielding shales appear. Sometimes a bed will be a coarse conglomerate, and in a short distance it will change into a fine sand- stone or even soft sand loosely held together. The irregular lamine of deposition and wave-marks are shown everywhere also, and the signs of quiet waters are local and of comparatively short duration. The map, when completed, will show a water-divide between the branches of the Gunnison and those of the Blue, trending about northwest and south- east, with Italian Peak at the southeast end, with Castle, Maroon, and Black Pyramid along the line, and ending in Sopris Peak. The numerous little branches will be seen extending down from this crest, uniting to form the larger streams on either side. All these little branches rise in broad amphitheaters which have been produced for the most part by erosion or the slow process of wearing out in a more or less circular or semicircular form by water and ice. These amphitheaters are numberless and occur on both sides of the crest. In many places the wearing out of the amphitheaters on both sides has been such as to remove hundreds of feet of the crest, thus forming a pass of greater or less elevation. In these amphithea- ters vast bodies of snow accumulate during the winter, a portion of which, in many instances, remains all the season. In the spring the process of thawing and freezing commences, and the slow breaking down of the amphitheater walls is continued. Thousands of little streams are formed by the melting of the snow, and the water flows down to join the main streams. All these great ranges of mountains are full of fissures, which, running in various directions, break up the entire mass. We can find these openings full of ice at almost any season of the year, and the well-known power of ice by expansion need not be stated here. This action will account for the vast quantities of débris all over the sides and sum- mits of our mountain-ranges. The more prominent the range of . mountains the more conspicuous is this feature, and the débris becomes most noticeable among all the great ranges of Colorado, as well as Montana. The Sawatch, Park, and Elk ranges are excellent illustrations of what I have attempted to describe above. From the crest or divide between the branches of the Gunnison and the Blue Rivers, the little branches have carved out deep valleys or gorges, nar- row or wide, depending much upon the texture of the rocks through which the stream has cut its way. Many of these valleys are covered 62 GEOLOGICAL SURVEY OF THE TERRITORIES. with thick grass far up on the sides, and even on the ridges between the streams, so that as a grazing region it must be excellent. At a period not far distant, this portion of Colorado must be settled to some extent by a pastoral people. We find, therefore, that from this crest or divide two great plateaus descend in opposite directions, forming, in the aggregate, a huge anti- elinal, cut deeply by the numerous streams that rise on the divide. This inclination, on the one side to the south or southwest, and on the other tothe north or northwest, is interrupted here and there by dikes of more mod- ern origin probably than the granite nucleus of the crest. Sometimes these dikes disturb the sedimentary beds, reversing their dip or produc- ing great faults, and again they penetrate some fissures without chang- ing their position. In the red sandstones that wall in the valley of the little branch just east of Teocalli Creek is a very interesting dike of the gray igneous granite, with a strike about northeast and southwest. It passes across a little fork just at its junction with the main branch, and is most distinctly seen at the summit of the wall on the west side. The ig- neous matter seems to have flowed up through the fissure without disturb- ing the contiguous strata of Triassic sandstone, which are nearly horizon- tal, and therefore there could not have been a great display of force. Itis probable that the origin of this dike is synchronous with the main nucleus, for the materials are apparently the same. As the little mount- ain-stream flows across the dike its greater hardness has formed a beau- tiful cascade. We might dwell long on the great varieties of beautiful forms which the crystal mountain-water assumes as it flows down the rugged gorges. A dike about 50 feet wide passing across the channel, the greater local hardness of the sedimentary rocks, or a reverse uplift, will produce cascades of remarkable beauty. Mr. Jackson, the photographer of the survey, has preserved a number of scenes from this region, and in each one of these almost numberless gorges that extend from the mountain-crest far down to the Green and Colorado Rivers, two hundred miles or more, there could be found many of these charming water-falls. Scenes of great beauty meet the eye at every step, and yet the area is so large that we must have left unseen by any member of the party views of even greater beauty and value. It is probable, however, that our determinations of the geologi- cal structure of the country passed over are substantially correct. A great portion of the surface is covered with a thick forest of pines. In the autumn the fires not unfrequently sweep through these forests, destroying their vitality, and soon the winds prostrate them in every direction, forming a net-work over which it seems almost impossible for our animals to pass. These difficulties are met with in the mountainous portions of the West; and in Montana, 1871 and 1872, our work was very much impeded, and in many cases arrested, by the intricate masses of fallen timber. The Elk Mountains are not more difficult of explora- tion on that account than the Sawatch range. In our description of the Mountain of the Holy Cross we shall allude to this fallen timber again. It is difficult for any one not familiar with this country to comprehend how important an element of hinderance this is in making a detailed exploration of the country. Very frequently we are obliged to cut our path through the logs for great distances, making only a few miles a day. At the head of Teocalli Creek is a high mountain-peak which we named Whiterock, from the fact that a seam of white or light gray igneous rock, 60 feet wide, passes through the middle of the summit vertically. The material is quite soft, disintegrating into mederately - coarse sand. The rocks composing the mountain are quite varied in UIVIUNOP, 1TVI0e7, i MEA et S H tie G55 yy! mteh a A AU Ms Bi es bhi “iy i \ Wadi alll 0 aise # "VL “OLA cata TM Pa a4 texture, though all evidently of igneous origin. The jointage is in many cases vertical, separating the mass into blocks varying in size from a few inches to 2 or 3 feet cube. This vertical jointage gives a sort of columnar appearance to the sides of the peak in the distance. The sides are also deeply furrowed. There are three sets of master- joints, with a multitude of smaller ones. The consequence is that the sides of the mountain and the several amphitheaters are covered with immense quantities of débris. The whole mass is filled with water and ice during the winter, and in the spring, as the ice and snow melt, it moves down the declivities slowly, like a glacier. Sometimes cavities or reservoirs are made, and the melted snows form beautiful little lakes. From the summit of Whiterock Mountain, which rises 13,563 feet above sea-level, the eye sweeps over a scene of apparent chaos on every side. There is a wilderness of high peaks with deep gorges extending out in every direction, 2,000 to 3,000 feet deep. The entire range is composed of what may be called upthrusts of igneous granite; that is, the granite is thrown up mostirregularly, at various elevations, from beneath the overlying sedimentary beds; sometimes carrying portions to the summits, or tilting them from the sides at various angles, or leav- ing them 2,000 or 3,600 feet below. While there are numerous points of upthrow in this region, there seem to be a number of foci of greatest power. The Snow Mass group and Whiterock Peak may be regarded as illustrations of tremendous upward force. From the summit of White- rock Peak the deep gorges with nearly vertical walls for 2,000 or 3,000 feet in depth, showing sections of the rocks as perfect as if cut down by human agency, can be seen on every side. Wecan see the junction of the stratified sedimentary beds with the granitic core. The variety of coloring to these groups is due to the different degrees of heat to which they have been subjected. The lowest group of sedimentary beds, although exhibiting all the stages of metamorphism, is usually of a yellowish-brown color, and made up of quartzites and impure lime- stones. I regard them as of Silurian age, and most probably Lower Silurian ; 500 to 800 feet are shown in this vicinity, but the aggregate thickness must be much greater. Then above this group there is a series of maroon or deep purplish-brown sandstones, quartzites, and con- glomerates. These vary much in color, from a light brick-red to a purplish-brown or maroon color. They reach a thickness of at least 1,500 feet, and probably more. This group is probably of carbonif- erous age. It may be found capping the highest peaks of Elk Moun- tains, over 14,000 feet above sea-level, and is weathered into unique forms of cones, pyramids, &c. The third series is a bright brick- red, and is probably of Triassic age. No one has, as yet, found any organic remains in any of these beds, and therefore we can only express a belief in regard to their age, strengthened by observations in adjacent portions of the district. From the summit of Whiterock Mountain the view on every side is most remarkable, presenting the aspect of chaos, as if the entire group of stratified rocks, which origi- nally covered the area now occupied by the Elk Mountains, had rested on a vast pasty mass of the granite, but which, by forces generated in this pasty mass, had been lifted up and tossed, as it were, in every direc- tion. The faults are very numerous and of huge dimensions. Some- times a group of strata is broken off, so that one portion is from 100 feet to 2,000 feet above the other portion. Sometimés 1,000 to 2,000 feet will be elevated by a force acting very nearly vertically, so that some of the loftiest peaks, as Maroon Peak, 14,000 feet; Black Pyramid, 13,000, and many others nearly as high, are composed entirely of strati- 64 GEOLOGICAL SURVEY OF THE TERRITORIES. fied rocks inclining at small angles. Again, the beds are tipped off from the granite core at all angles from 10° to a vertical, and not unfre- quently past a vertical, and there are in the Elk range the most won- derful instances of the complete overturning of immense groups of beds, so that for several miles there is a double series, from the Silurian up to. the Cretaceous, inclusive, and then rising upward in inverse order, as is. shown at the head of East River and near Snow Mass Peak. Again, the two forces, one vertical and the other tangential, seem to: have acted at the same time, throwing 1,000 feet or more of older strata directly over rocks of more recent age. The complications are so great in the Elk Mountains that we could only make a preliminary survey, and a special study must be made of this entire range. This. we propose to do the coming season. By looking at the map of Elk Mountains it will be seen that several streams have their sources in the Whiterock Peak. The little branch that rises at the north side and flows around to the southward has already excavated its amphitheater back nearly a mile, while the granite here is rounded or smoothed as if by the movements of masses of ice, though much of the erosion must have been performed by the movements of vast masses of loose earth and débris. From the real base of the mountain one can follow up this gulch for several miles, rising, as it were, step by step, on a series of irregular terraces, which are the result of these accumulations of débris. In this instance, the difference of elevation of the real base of the peak and the immediate foot of the crest is at least 2,000 feet, and the width from a fourth to 4 half a mile, so that one can arrive at a moderate estimate of the tremendous work of erosion which has been performed here. Atthehead of this amphitheater: the crest is so narrow that it was with extreme difficulty that we could creep along it, and we could look down on every side into similar exca- vations. These mountain-ranges, of which the high peaks now form the conspicuous features, were originally of considerable width, varying from half a mile to several miles, but now the crest or divide may be represented on the map as a zigzag line; the sources of the little streams. running not unfrequently from them, having already removed this crest for a little distance, thus forming a kind of low pass. The sides or walls of these gulches are usually very steep, in many cases vertical, but when the upper portions are composed of the easily disintegrating sandstone, the vegetation, of a most vivid green color, has crept high up on the sides, and the upper border is composed of a series of tongue-like points, which give to the picture a unique appearance. It would appear as if the grass had struggled ineffectually to scale the sides of the gulch to the very crest. In some instances these little tongues or points do: extend 20 to 50 feet above the main mass below. The melting of the snow forms little furrows down the steep sides, and between them are: the sharp points or tongues of vivid green vegetation. Ascending the valley of East Creek near its source, we pass over the sands and clays of the Cretaceous group, containing afew characteristic: fossils, as the Baculites ovatus, and several species of Inoceramus. AS we proceed west and northwest the Cretaceous rocks increase in thick- ness and extent. The valley of the Hast Fork, as we see it near Gothic: Peak, is a kind of monoclinal, the rocks apparently inclining in the same direction, the west side being abrupt, while the east side has a steep slope. Gothic Mountain is composed of a vast mass of igneous. granite projected up through the superincumbent beds of stratified rocks, . perhaps raising them toa greater or less extent, but apparently not. changing the horizontal portion of the Cretaceous beds, which are all. HAYDEN, ] GEOLOGY—ELK MOUNTAINS. 65 the sedimentary rocks that are visible around the base. There are the black shaly clays which occur above the Dakota group, and whenever they are in contact with the granite core, they are metamorphosed into slates. Debris covered with vegetation conceals the slates below the igneous core for the most part, but on the steep sides a considerable area is exposed here and there, and, so far as we can see, the disturbance has not been great. Just on the opposite side of the stream a bed of blue limestone rises up from beneath the black shales filled with Inoceramus, probably of the age of No. 3. This limestone is partially changed by heat. A little below the Gothic Mountain the stream cuts a gorge through this limestone, with walls 30 to 50 feet on either side, quite compact, and resembling mason-work. The black clays of the Creta- ceous extend up Gothic Peak more than half-way above the bed of the stream, 1,000 feet or more. Near the top of the shales there is a band of trachyte which extends through the peak, along the side of the ridge, to the sources of East Fork, several miles above the peak. It is undoubtedly a dike separated from the main mass of the peak by a band of shales. As it appears to one ascending the valley, it seems like a rocky stratum of irregular thickness interstratified with the black shales. The valley is in part one of erosion. From margin to margin it varies from one to two miles in width. At the upper end the stream separates, one branch extending up into the ridge on the east side, and the other cutting its way through the cross-ridge that separates the Hast Fork Valley from the branches of Rock Creek. ‘The west branch cuts through the cross-ridge of which Bellevue Peak is the prominent point. At the summit of the divide, which is full 800 feet below the summit of the ridge, there is a beautiful green lake fed by the melting of the snows; and it would be easy to believe that in seasons of high water the little lake drained both ridges into Rock Creek north, and into East River south. This might be given as a well-marked example of a two-ocean lake if it were situated on the main Rocky Mountain divide. On the east side of the source of Hast River are the red beds in their full development, and on the summit the quartzites, yellow, drab, and ‘brown, varying in intensity, depending upon the amount ot heat to which they have been subjected. The cross-ridge which sepa- rates the drainage of Hast River from Rock Creek trends about east and west. We pass over this ridge and descend into a deep gorge-like valley, with its side-gulches cutting deep through the ridges. This cross-ridge shows a complete subversal of the sedimentary group from the quartzites to the Cretaceous inclusive. Bellevue Peak is made up of two sets of Cretaceous beds, the upper series being reversed, so that the lowest portion caps the summit of the peak. ‘This peak is literally riddled with dikes that have changed the shales into slates. This cross- ridge is a part of a long ridge of overturned strata with a trend west to north ten to fifteen miles in length, extending to Snow Mass Mountain. Dikes of trachyte project from the sides of the ridges at different eleva- tions, varying from a few feet to over 100 feet or more, and resembling in the distance massive beds of gray sandstone interstratified with the Shales and clays of the sedimentary group. Here and there these dikes are nearly vertical, or incline at a high angle in the side of the ridge. From Bellvue Peak we followed a trail on the east side of Rock Creek Gulch, just below the summit of the ridge. The sides and bottom of the valley were composed of the Cretaceous clays with the beds of lime- Stone containing characteristic fossils. As we ascend the ridge we find the entire Dakota group overlaid by the Triassic, passing up into red beds, showing most clearly that for ten to fifteen miles the great mass 5GSs 66 GEOLOGICAL SURVEY OF THE TERRITORIES. or aggregate of the sedimentary strata has been completely overturned. A careful, detailed study of this interesting locality would show very many instances of this overturning of the beds as well as faults of the most remarkable character. From Bellevue Peak we started for the Snow Mass range in a northwest direction. The dikes in the Cretaceous strata were very numerous. The igneous matter seems to have been forced up through fissures in the rocks which were produced by the uplift. On the west side of our trail the little stream which has worn out the deep eahon and forms the south branch of Rock Creek presents in the walls a wonderful display of the beds inclining about southwest 5° to 10°. The strata here indicate in a marked degree two primary movements, the vertical and tangential. The summits of the ridges on the west side of the high mountain-ridges, at least 13,000 feet above sea-level, are capped with the black clays and quartzitic sandstones of the Cretaceous group, while underneath are the variegated sandstones and quartzites, more or less changed by heat. These rocks present every degree of change to the most compact quartzites or slates. The whole must have rested upon a viscous mass, and by strange manifestations of the force the superincumbent strata have been tipped in every direction, and through the fractures thus formed was squeezed, as it were, the melted granite, forming the numerous dikes which occur everywhere and of every pos- sible form and size. Sometimes an aggregate mass of several hundred feet of well-defined strata is bent in graceful curves. These examples of flexure are very numerous, and vary from a slight bend to an are of acirele. The gorges which are cut deep down into the sides of these ridges display the flexure as well as the faults and dikes in a remark- ably clear manner. The variegated color of the beds adds greatly to the picturesque beauty of the scenery. The Snow Mass range presents one of the most marked examples of the complete subversion of the strata by the elevation of the great group of granite peaks which form the core of that range. Our camp was made in the valley of Rock Creek, on the south side of the range. The high ridge which extends down from the southwest side is composed of the double set of strata. The lower group, which holds nearly its normal position, inclines at a small angle, while turned completely over on this set or group is the same series in reverse order, like the overlaying of sheets of paper or cloth. The Cretaceous shales are at least 60° past a vertical, while the Jurassic, Triassic, and older beds incline at various angles, varying from 60° to 40° past a vertical. The great group of peaks which formed the center of the movement rises nearly 14,000 feet above the level of the sea, and is composed of massive granite. The jointing of this granite is very marked. One sf the master-joints is vertical with a direction about east and west. The joints are not all as regular as the vertical, but they are so well defined that the mountain is much broken up, and easily yields to the influence of air and moisture. The sides and base of the range are covered with an immense quantity of débris, the masses of rock varying in size from a few inches to 20 or 30 feet in diameter. In some instances the sides of the mountain seem to be made of massive layers that break off in folio, asif the granite had cooled in concentric layers. The entire range is in this way slowly but constantly falling down, so that from base to summit the talus is quite remarkable in quantity. At the basezon the south side, there is a beautiful lake about 300 yards long and 150 wide, on which an abun- dance of water-birds were swimming ‘and feeding. Thisis named on the map Elk Lake. The summit of the mountain is massive igneous granite, remarkably compact. From the top of Snow Mass Peak the view is HAYDEN. } GEOLOGY—ELK MOUNTAINS. 67 very extended and grand. To the south we can see the country we have just passed over from the Sawatch range. In the foreground the series of sedimentary beds on both sides of Rock Creek, which have been subverted by the uplift of the Snow Mass group, the great sedimentary covering laid off from the granite as the covering of a bed is drawn over from the pillows. At the southeast the lower beds, or those that run next to the granites, are nearly vertical in position, but the newer or higher ones geologically are tipped far past a vertical. Farther still to the south, across the gorge, is a ridge covered with snow, from the sides “ of which ocher and maroon strata incline at various angles, on one side about east, and on the other west, while the nucleus is a mass of igneous granite. To the eastward, extending a great distance, the red beds can be seen inclining at various angles for the most part from the central mass, but full of dikes. It would seem that the cones and pyramids formed remarkable cross-sections, showing fissures of various widths, through which the igneous matter came to the surface. Twenty or thirty of these dikes of all sizes are in sight on the east side of Snow Mass Peak. These dikes present a great variety of forms. Sometimes the igneous ma- terial has flowed up through vertical fissures, as in the maroon ridge to the southeast. In the same ridge the igneous matter has come to the surface and overflowed, so that the ridge is capped with the granite. To the north- east there is a red ridge, with a wide vertical dike through which the igne- ous matter has come up from the central mass and overflowed, forming a cap to the ridge. At another locality to the northeast we can see dis: ° tinetly the ocher beds, or the lowest sedimentary group, probably Silurian, resting on the granite, inclining 10° to 15°, and on these a great thick- ness of red beds, and on top of the latter masses of irregular thickness varying from 100 to 400 feet of the eruptive granite, and at either end the red beds again, resting upon the eruptive mass. In this case the eruptive material must have been pushed up through a fissure in the lower strata, and toward the summit lifted up the upper red beds, so that it now appears like an interstratified mass. For twenty or thirty miles from Snow Mass Peak to the northward between east and west, the red or maroon beds rise in high, long ridges, with immense valleys and gorges between. To the northwest are portions of the Snow Mass group and Sopris Peak, all, parts of the great central granitic mass or nucleus. Far in the distance, westward, thirty miles or more, is the valley or cation of the Grand River, with stratified beds of a light red on either side. Inthe amphitheater on all sides of this granitic nucleus are quite remarkable glaciated rocks, with great numbers of beautiful green lakes, which form the sources of numerous branches of the rivers. These are reservoirs for the reception of the waters of the melted snows which lie in glacier-like masses on the sides of the mountains. The same proofs of the wearing away of these central masses is shown in this range which we have so often observed in the preceding chapters. The crest is a thin, sharp ridge, in many places so narrow that it is with difficulty one can creep along it. It is remarkably zigzag in its strike, enormous amphitheaters having been excavated on both sides, in many instances having broken through the crest, either from one side or the other. On the east side of Snow Mass group there is a fine, large amphithe- ater in which are several small lakes with vast quantities of broken rock, and just above them, on the side of the crest, a vast glacier-like mass of snow and ice, from which, at this season of the year, (August,) water is flowing rapidly. We might suppose that in old glacial times each one of these amphitheaters was the abode of a glacier which each 68 GEOLOGICAL SURVEY OF THE TERRITORIES. year slowly moved downward, carrying with it great quantities of earth and fragments of rock far below. The time for this action in its full force is now past, and the work of excavation could not have been per- formed, as we see it has been done in past ages, with the forces now in operation. Between the two main peaks, each of which is nearly 14,000 feet high, the crest curves so as to form a full semicircle, and has been worn away so that it is now 500 to 800 feet lower than these peaks, though it must have been originally of the same height atleast. We may see that it is most probable that much of the original form of these mountain-ranges has been lost, and that their present shape is the result of atmospheric forces acting through ages—from the time of the uplift to the present day. It is also evident that these eroding agencies operated with far more power in the past than at present, and that it is most probable this foree has been decreasing slowly to the present time. The Blue River range is a fine illustration of the same process of excavation. The Snow Mass Peak is really a long, sharp ridge with two points, the northwest point “being about 300 feet higher than the southeast one, while between the two the crest has been worn away so that it is 600 to 800 feet lower than the two ends. ‘The shape seems to be given by the flexures of the jointing. The sides are deeply furrowed, down which it'is probable that masses of snow and ice have slidden for ages. On the south side these furrows are very deep and regular, and at about the same distance apart, so that the curved form appears like a series of waves, extending from the summit down into the amphitheater. There can be no doubt but that they have been worn down by the combined action of water and ice. Thesquare masses of granite stand up on these crests or ridges like druidical columns. The remarkably broken condition of the rocks composing the entire nucleus of these mountains would indicate immense wear, and that all these peaks which are now very lofty were once much higher than at the present time. On the south side of Snow Mass, near its base, there are vast masses of igneous rocks that appear to be of more modern age. Much of the basalt being porous like slag. Itis most probable that the igneous rocks are of different ages, and while none of them in their present form may be older than the Cretaceous period, there may have been eruptions of greater or less ex- tent all the way up to the present period. In tracing the channel of Rock Creek up from our camp, we find the black Cretaceous clays dip- ping past a vertical 50° to 60°. ‘The channel of the little stream reveals a complete section of the beds in their order, as well as their position. We find two distinct sets of beds, the upper reversed, so that at the upper falls we find the quartzites of the Dakota group on the black clays of No. 2, and the latter over the limestones that usually charac- terize No. 3. Near the lower part I obtained quite a collection of well- marked Cretaceous fossils, among them Baculites, Inoceramus, and many small shells. In the gray limestone are numbers of a high, round Jnoce- ramus identical with the species found on the east slope of the Rocky Mountains. In No. 21 found Ammonites, Ostrea congesta, and a small Shell with scalloped edges like O. larva. These shales and clays are more or less metamorphosed at different Localities. In the little streams that flow from the high mountains are nu- - merous beautiful cascades. There is in most instances a reason why the water should be interrupted; and there are two excellent examples in this stream above our camp toward its sources. The upper falls are produced by the water flowing over the hard \ GEOLOGY—ELK MOUNTAINS. 69 i] . HAYDEN. | quartzites of the Dakota group, and thus the wearing out of the channel was interrupted by the great hardness of the rocky bed. The lower falls were formed by a dike, which commences on the left branch, runs parallel with the strata for 20 or 30 feet, forming the top of the falls, then drop down diagonally across the layers of shale about 10 feet, and on the opposite side rises again and is lost in the débris. At first the trachyte is above a hard layer of caleareous sandstone about 2 feet thick, but it passes through that into the softer clays below, where its thickness is increased from 2 to 4 feet. Both the upper and lower sides of the dike-layers the Cretaceous shales are changed into slates and are adherent. As we follow up the channel of the stream to a high hill overlooking the gorge, we see that the entire mass on both sides, and extending for miles, has been thrown over to the west and southwest, and that the occasional sagging or bending down of the mass produces a drainage-channel through which the little streams find their way. In the case of Rock Creek, the curve down- ward or sag is 600 to 1,000 feet. At another locality near this creek there is a dike 4 feet in width, nearly vertical, or running across the Strata at right angles. We see, therefore, that the igneous matter was pressed up through every fissure of any form through which it could gain access to the surface, or relieve the pressure from beneath. Some- times it is squeezed out between the layers or strata across them diag- onally, or at right angles, in whatever direction the original fissure might take. As we descend Rock Creek the channel reveals the lower set of beds from the Cretaceous shales of No. 4, downward to the gran- ites, with the various changes which they undergo. The shales, mud sandstones, and clays, of No. 4 and No. 2, as well as the gray limestones of No. 3, are frequently much changed. The black quartzites on Rock Creek, and the blue limestones, with all the intermediate steps of change, are most clearly shown. The gorge or channel is inclosed within nar- row walls, which soon increase in height from 1,200 to 1,500 feet, inclining at a moderate angle, 5° to 10°, about northwest, or nearly opposite,to the dip from Snow Massrange. Gothic Mountain, 12,315, and Crested Butte, 11,838 feet high, may be regarded as immense dikes, the melted mat- ter pushed up through the superincumbent strata, but in such a way as not to disturb to any great extent the great thickness of yielding Cretaceous shales and clays, so that they surround the base of the mountains like terraces, apparently in a nearly horizontal position. Gothic Mountain presents an illustration not only of the vertical up- thrust by which the central mass was brought to the surface, but also shows an irregular layer of the trachyte squeezed out between the strata of shale. We have not been able in this chapter to present more than a glimpse of the remarkable geological features of the Elk Mountain range. It is the purpose of the survey to make a careful examination of this entire region as a special study, and therefore only a preliminary notice of it can be given in this report. We have frequently spoken of the chaos into which the beds seem to have been thrown by the numerous centers of uplift, and so it seems at the ‘first glance; but our map will show that the massive peaks are located along a regular line which indicates a true axis of uplift, trending northwest and southeast. Studied in de- tail, the geologist will find faults and dikes without number, strata in- clining in every direction and at all angles, and very often entirely sub- verted, yet the aggregate dip and strike may be reduced to a system, as we see it on the map, from Italian Peak to Sopris Peak. 70 GEOLOGICAL SURVEY OF THE TERRITORIES, CHAPTER IV. FROM ELK MOUNTAINS TO MIDDLE PARK. After a preliminary exploration of the Elk range was completed, the party returned by way of Twin Lakes around the Arkansas Valley and across the divide by way of the Tennessee Pass. AS we pass up the valley and examine the comparatively smooth ter- races that are well shown on. both sides, as well as the wooded foot-hills, we form no conception of the deep gorges or cafions which are found between the mountain-crests. Above the entrance of Lake Creek into the Arkansas, the valley is quite wide, though the immediate bottom is narrow, but the evidence of erosion in the subsequent deposits of de- trital matter is very marked. Just opposite Massive Mountain the river-bottom is about a mile in width; then a terrace rises 40 feet above, and a second terrace of 500 feet, composed of horizontal strata of sand, clays, sandstones, and conglomerates, a kind of modern lake-deposit. The distance between the immediate base of the Park range on the east side of the Arkansas and the Sawatch on the west side is about ten miles in a straight line. A coarse bowlder-drift or detritus covers the foot-hills to a considerable depth, while beneath are the worn surfaces of the granite rocks, which have most probably been ground down from their lofty heights by the old glaciers that once filled the valley. The evidence shows that the waters of the Post-pliocene lake were 1,200 to 1,500 feet above the present river-bed. In the mountains to the west of the pass some valuable silver-mines have been discovered, and the Homestake district laid out. Very littleis known of them as yet, except that about seventy tons of ore have been taken out and trans- ported to a smelting-furnace near Denver. The yield is reported to be from $100 to $200 of silver per ton of ore. The Tennessee Pass forms the water-divide between the sources of the Arkansas and some of the south branches of the Blue River, as the Roaring Fork. The height of the pass is 10,223 feet above sea-level. The country on both sides of the divide is covered quite thickly with pines, with here and there openings like meadows. ‘The pine-forests are destroyed more or less every year by fires, which sweep over large areas. Unless the autumnal fires can be checked, the pine-forests of all these mountain-districts must disappear. At the present time the various branches of the Arkansas are choked up with ties which are to be floated down the main river toward Pueblo for the use of the Atchison, Topeka and Santa Fé Railroad. Remnants of the sedimentary rocks appear here and there about the divide, but the basis rocks are so covered with débris or detritus that it is hardly possible to determine them. It is most probable the granitic rocks prevail. As we descend the west side of the pass in the narrow gulch of Eagle Creek the gneisses, with well-defined bedding, are seen on both sides for two miles, when patches of stratified quartzites occur, resting on the upturned edges of the gneisses. About ten miles below the Tennessee Pass, on Eagle River, on the sides of the gulch, we have gneiss, with dikes of trachyte; white quartzite Stratified, 30 feet; reddish quartzite, full of seams of white quartz and much changed by dikes. The quartzite passes up into a quartzose sandstone, rather coarse, 100 feet; yellow-brown arenaceous mud, lime stone alternating with seams of shale and quartzite; coarse and fine sandstone of various textures, with layers of limestone interstratified, LAL WOO U0 ‘USPUDY “Ying Jo Lnuppog mynhaLty oi) ; je “i islet 4) = Tyllit gf ie i Hi ius ue jae ge if , = ee i, foe os sare a os - H =| Nees Ol came age 5 SRS py Sy \ "i nv my | ——— a = N L \ Ne e » i WE = . a ’ \ 1 we! =) a \n " \ AN ST Ny : SM aly! re r Wil x SS Awan yar ‘Nl HNN mie i te i\ fel = ea wna naypex.) GEOLOGY—FROM ELK MOUNTAINS TO MIDDLE PARK. 71 with partings of shale. The layers of limestone vary from 4 inches to 4 feet in thickness. As we ascend the sandstone predominates, and becomes coarser until layers of rotten coarse sandstone alternate with beds of pudding-stone and conglomerates. Some of the sandstones are quite coarse in texture, and might be called pudding-stones. Indeed, the whole section is a repetition of the one near Horseshoe Mountain. The stratified beds are here over 1,000 feet in thickness above the bed of Eagle River. It would seem, therefore, that we have here on the west slope a series of quartzites and impure limestone, like those resting on the granites in the Park range, and most probably of the age of the Lower Silurian ; above them athick group of Carboniferous beds with num- erous fossils, as Spirifer, Productus, and a trilobite, probably a Phillysia. These fossils are found quite abundantly as soon as the more modern beds occur. To the eye of the field-geologist this lower group of beds presents a much more ancient aspect, where it is seen, than the Carbon- iferous, although there are no remarkable instances of inconformability that have come to my notice. I think I can always detect the line of demarkation between the older group and the Carboniferous series in all cases without the aid of fossils or other proofs, merely by the differ- ence in the general external appearance. As we pass lower down the valley of Eagle River, we-find high bluff-walis on bothsides of the river, with several hundred feet of rather loose arenaceous beds with hard layers of sandstone and quartzite alternating, of yellow and brown color, evidently extending the Carboniferous group 800 to 1,000 feet above the reddish-brown sandstone. This upper group of beds rises to the summit of the ridges as we ascend the river, and probably forms the upper portion of the Carboniferous series. The color of the rocks in this region cannot be depended upon as of any value in tracing groups of strata over large areas. The same white quartzites which we have mentioned above as resting ‘upon the gneiss a little farther below hold the same position, but are quite red. They may be white, gray, red, rusty-yellow, or brown, within comparatively short distances. In the canon of Eagle River the order of superposition is well shown. The cafion is undoubtedly one of erosion for the most part, though, like that of the Arkansas River, it is also monoclinal. At the present time the indications of any original fracture or fissures are only suspected by the inclination of the stratified beds on either side of theriver. The dip is to the east and northeast from the great Sawatch range, of which the Mountain of the Holy Cross isthe northern end. The erosion has been so great that the sides of the cation for miles are nearly vertical, although the left or east sidé is much more abrupt. Sometimes the quartzites that rest on gneiss will wall in the valley at the river’s margin; again they will cap the summit of the ridges 1,000 feet or more above the bed of the river. ; Both sides are penetrated with dikes to a greater or less extent. At one locality, above the Silurian limestone, is a bed of trachyte, apparently interstratified, with a bluff-front of 50 feet, with marked vertical and horizontal jointing. So far as I could discover, it does not extend horizontally more than 100 yards. Sometimes the igneous material rises up through vertical fissures without much disturbance of the con- tiguous beds, and again it throws it into chaos, so that while the gen- eral or aygregate inclination is north or northeast, the local dip is liable to be in any direction or at any angle, depending upon the force exerted by the igneous outflow. As we strike the main branches of Hagle River and they unite, the main river flexes slightly toward the west, 12 GEOLOGICAL SURVEY OF THE TERRITORIES. and the monoclinal character of the cafion becomes more apparent. ~ Fragments of the quartzites may be seen on the west side, high up on the granites inclining northeast; while on the right or east side they incline in the same direction and dip beneath a vast thickness of varie- gated sandstone and shales. At first the high mountain-ridges, 1,200 to 2,000 feet above the bed of Eagle River, are granite or simply capped with patches of the quartzite. As we descend the Hagle River an increasing thickness of the sedimentary beds is observed on that side, forming a steep slope, while on the right or east side the abrupt edges of the variegated sandstone and shale rise at least 2,000 feet, forming the high rounded ridge between the Holy Cross and Blue River groups. Opposite the junction of Roches Moutonnés Creek with Hagle River there is a very high, nearly vertical, bluff, showing a re- markable section of the variegated beds, which are probably of Carbon- iferous age. We have already noticed the quartzites resting on the granites, and above the quartzites are impure arenaceous limestones. As we descend Eagle River, these rocks, which have a more ancient aspect, and which I regard as of Lower Silurian age, pass beneath the bed of the river, at the entrance of Roches Moutonnés Creek, and we have on the east or right side of the river the series of strata whieh may be described briefly as follows, in ascending order : 1st. A group of rather light-red sandstone, varying in shades of color, oftentimes in massive layers varying from a few inches to 30 feet thick, with partings of arenaceous shale, varying from a few inches to 6 feet in thickness. The two upper layers of sandstone are fine-grained, and break into quite regular vertical columns. The lower bed is about 12 feet thick. The layers or strata are all irregular in thickness in the horizontal extension, sometimes thinning out to a few inches, and then increasing to several feet. In texture the rock presents every shade from a fine-grained sandstone to a coarse conglomerate, and these changes may occur in the same stratum within a few feet. There are twenty-two layers of sandstone in this group, varying from 2 to 30 feet in thickness, and the aggregate thickness is about 500 feet. Some shade of red is the prevailing color. 2d. Then comes a series of similar beds, evidently portions of the same group, but in this locality marked by difference in color, being mostly yellowish-gray or brown, sometimes with a reddish tinge. The first bed is about 6 feet thick with the same vertical columnar fracture, which at a distance gives to the rock the appearance of basalt. This group comprises twenty-four beds of sandstone, varying from 2 to 46 feet in thickness, with shaly partings varying from a few inches to 4 feet. This upper group is much finer in texture than the lower group, yet all the layers indicate the deposition of the sediments in shallow as well as moving waters, by the oblique lamine and the irreg- ular thickness from point to point. The shaly partings are in many cases very micaceous, and might be termed micaceous shales; while the coarser sandstones, or pudding-stones, are made up of pebbles of quartz mostly, and so far I could detect no fragments of the sedimentary rocks. The shales are also variable in color from yellowish-brown to a light gray, then changed into what may be called mud-sandstone, in groups vary- ing from 50 to 200 feet in thickness.. Sometimes the mud-shales are separated by a few feet of coarse sandstone or quartzite. ‘The difference in the texture of these layers may be detected at a distance by the style of weathering; the sandstones fracture with a square vertical HOPSON-SHERMAN.SC. + x TAR a Se YOAP bi SMOLIN BBO ing C ~d Section ot upturned strata, Snow Mass Range. (See page 66.) a, Cretaceous. 0b, Jurassic. ¢, Triassic. d, Carb. e, Granite. View on Roches Moutonnes Creek. (See page 73.) HAYDEN. ] GEOLOGY—FROM ELK MOUNTAINS TO MIDDLE PARK. 73 face, while the quartzites weathered in rounded forms, the thin layers dropping off concentrically. The composition of those rocks would indicate that the gneissic or granite rocks were very largely drawn upon for the materials. The two groups described above will aggregate at this locality about 1,200 or 1,500 feet in thickness; but as we descend the river we can see on the summits of the mountain-ridge a great additional thickness, so that the whole must sum up at least 3,000 or 4,000 feet. The character and texture varies much in different localities, but the description given above will apply to a great thickness of beds which extend over a greater or less area west of the Sawatch range to the Colorado River. Our trip down the Eagle River had for its principal object the dis- covery of some way of access to the mountain of the Holy Cross. A little stream joins the Eagle River from the west side, which rises among the group of mountain-peaks of which the Holy Cross is most conspic- uous. The valley of this stream varies from one-eighth to one-fourth of a mile in width, and is about eight or ten miles in length, and so cov- ered with the rounded glaciated forms of granite that it was impossible to ascend it with our pack-trains. We were obliged to descend the river about three miles and then climb the steep mountain-side over a net-work of fallen timber. The obstructions to traveling were very great. We often labored for a day or two to find some path to approach the mountain-peak, and were obliged to cut our way through the fallen timber, and finally succeeded in getting within about five miles of the base of the peak. Fhe most remarkable feature of this wonderful region is the proof of agreat ancient glacier which must have filled up the valley from mouth to source. The bottom, extending high up on either side, is covered , with the rounded granite masses, varying in size from a few feet to sev- eral hundred feet length ; so that, looking down upon them from a high point, they resemble a huge flock of sheep, and from this fact they have received from the Alpine geologists of Europe the appellation ‘of ‘Roches Moutonnés.” It is most probable the valley itself has been worn out of the granite mass. The mountains on either side rise to the height of 2,000 to 3,000 feet above the valley, and the glacial markings are visible 1,200 to 1,500 feet. The morainal deposits on the northwest - side reach a height of 1,200 feet above the stream and form a sort of irregular terrace, which, when cut through by the little side-streams, show that it is made up of gravel and bowlders much worn. In some instances there are: well-worn cavities in the sides of the mountains, showing how ‘the running water, in connection with a mass of rock, formed the cavity much as a “ pot-hole” is made in our streams at the present time. Many of the “‘sheep-backs” are still covered with a crust like enamel, but usually this has peeled off. There isno doubt that all these rounded eranite masses were originally covered with what may be called a glacial crust which has scaled off, so that only remnants remain at the present time. The rounded masses of granite are mostly oblong in form, or lie in parallel lines, as if the little stream had originally occupied a dozen or more channels parallel to each other. The amphitheaters on the west side of the mountain are quite numer- ous, at least a half-dozen in number, giving birth to as many streams that flow down the mountain-side. These unite in the valley, and form a good-sized stream, 150 feet wide and 2 feet in depth. At the upper end there is a boggy meadow covered with high, coarse grass. This meadow is about one-fourth of a mile in length and about 74 GEOLOGICAL SURVEY OF THE TERRITORIES. the same distance in width. This must have been originally the bed of a glacial lake, scooped out by glacial action as a sort of reservoir for the . sediment swept down from the mountain-sides. The sheep-backs com- mence at the lower end of this basin and continue for about ten miles, presenting undoubtedly the most remarkable illustration of this partic- ular kind of glacial action ever seen on this continent. The main mass of the peak, like the whole of the Sawatch range, is composed of granite gneiss; The summit of the Holy Cross is covered with fragments of banded gneiss. The amphitheaters on all sides have been gradually excavated, as heretofore described, and the more or less vertical sides show the intermediate steps very clearly. The character- istic feature of the Mount of the Holy Cross is the vertical face, nearly 3,000 feet on the side, with a cross of snow which may be seen at a distance of fifty to eighty miles from other mountain-peaks. This is formed by a vertical fissure about 1,500 feet high, with a sort of horizontal step, produced by the breaking down of the side of the mountain, on which the snow is lodged and remains more or less all the year. Late in the summer the cross is very much diminished in size by the melting of the snow which has accumulated in the fissures. A beautiful green lake lies at the base of the peak, almost up to timber- line, which forms a reservoir for the waters from the melting snows of the high peaks. From this, one of the main branches of the Roches Moutonnés Creek flows down the mountain-side, forming several charm- ing cascades on its way. The worn rocks or ‘‘sheep-backs” in the valley of the creek display most remarkable examples of the curious markings on the surface of gneiss produced by the separation of the different constituents of the rocks. i The red feldspar sometimes makes bands or seams crossing each other like mosaic work. Then there are patches of all sizes and shapes, in which the particles of mica are so fine that they appear like rounded masses inclosed in a coarse feldspathic matrix. : Many of the rocks look asif they were covered with a confused mass of hieroglyphics. These peculiar markings in the structure of gneiss are not uncommon, but they are shown on such a scale in this locality as to attract attention. We have already described the cafion of Eagle River as monociinal in part. It runs nearly parallel with the upheaved ridges, but as it descends passes into the sedimentary beds from the granites to the Cre- taceous clays of No. 4. At first the cation cuts deep into the granites, 1,000 to 1,500 feet, with vertical sides; soon the quartzites come in rest- ing on the granites, and then cherty limestones of the thickness of 1,000 to 1,500 feet, which are undoubtedly a part of the same group seen in the Park range, on the west side of the South Park, and regarded as of Lower Silurianage. The channel cuts through an enormous thickness of variegated beds, not only in color but texture; a most remarkable group, with an aggregate thickness of 3,000 to 4,000 feet. That this group is of Carboniferous age, the few fossils that could be detected in different localities seemed to testify. As we descended this stream toward the main Blue River, the high sloping ridges are seen on the left or south side, the dip well exposed in. the channels of the streams that have cut deep down from the mountain-crests. Great quantities of worn bowlders and loose detritus cover these ridges, growing more abundant toward the base or near the river. On the north or right side the outcropping edges of the sand- stones and indurated clays and shales are seen, the texture determining the abruptness of the sides of the canon. Mountain of the Holy Cross. saxpex] GEOLOGY—FROM ELK MOUNTAINS TO MIDDLE PARK. 15 There are great numbers of side-cafions formed by the little streams that have their origin high up in the Blue River range. We find here two forms of river-channels or cafions; one nearly parallel with the lines of fracture, monoclinal, as I have called them for want of a better term, and the other at right angles to the ridges and carved out of the solid mass. In the first class the drainage must have commenced in a fracture, but erosion has been the main agency in the formation of the cafion; in the latter, the channel is in most instances entirely due to erosion, the strata corresponding in position to a greater or less extent on both sides. Between the northwest end of the Sawatch range and the Blue River range there is an immense mass of sedimen- tary strata crushed in between the two great axes of uplift as it were, forming a sort of synclinal. The beds incline with tolerable regularity from the Sawatch toward the northeast, though the dip varies from 10° to 50° or 60°. Sometimes the dip, close up to the margin of the mount- ain-summits, is nearly vertical, but in a few instances great masses of strata seem to have been carried up on the underlying granite, produc- ing extensive faults, as seen in the Park range. But the elevation of the Blue River range seems to have been somewhat peculiar, the force having acted nearly vertically, so that on the west side of the range the sandstones jut up against the sides with but a slight dip. Following up one of the branches of Hagle River, which rises high up in the west side of the range and carves a channel across the uplift, we find the in- clination from Hagle River extending eastward for about six miles, — where there is a sort of sag or depression and a reversed dip from the Blue River range. From Eagle River Valley we made a side-trip to the Blue River range, ascending the highest peak, Mount Powell, by way of one of the little streams that rise on the west side. There is no name for this little stream, but it reveals in the sides of its cafion a thick group of the brick-red sandstones. The cation is carved out of the solid mass, from the amphitheater high up on the west side of the range, down for sev- eral miles through the sandstones at right angles to the inclination of _ the strata. The sides of the cafion are 1,200 to 1,800 feet high on either side, and rise in abrupt steps, depending upon the texture of the differ- ent layers of sandstone. The valley varies from one-eighth to one- fourth of a mile in width, and rising up in various places in the bottom are the worn edges of the sandstones. At one place they appear above the surface completely across the valley, showing most conclusively that this gulch or cafion is entirely one of erosion. On the west side of the Blue River range the sandstones lap on to the granite nucleus, so that the usual valley of separation is wanting ; or, in other words, the ridge of sandstone lies so close to the mountain- side as to be continuous with it. As far as one can see from the summit of Mount Powell, north and south, these sedimentary beds hug the west side of the range with a very moderate dip, not usually over 10°. There are numerous streams that flow from the west side of the range and cut deep channels, which expand or contract, depending upon the texture of the rocks through which the erosive agent has wrought its way. Tiverywhere there are more or less proofs of old glacial action. The moraines are common, but not on such a scale as we have already de- scribed, on either side of the Sawatch range. In the amphitheaters, as well as in the upper portion of the valleys where the granites are ex- posed, we find the same rounded glaciated masses which were so con- spicuously shown near the Mountain of the Holy Cross. 16 GEOLOGICAL SURVEY OF THE TERRITORIES. The effects of erosion, as shown in the Blue River range, are on equally as grand a scale as in other localities previously described. Hven the imagination fails to grasp the tremendous influence this agency has exerted in past times, judging from the scenery both of mountain and plain. From the summit of Mount Powell one can follow with the eye the sharp, zigzag crest of the Blue River range, with the numerous huge amphitheaters on each side, which have been worn a long distance from the base of the mountain. Very frequently the partition-wall is broken through, forming a low bend or sag in the crest-line, and here and there a huge shaft of granite rises up 1,000 feet or more above the crest. The Blue range, as seen from the summit, is one of the ruggedest in Colorado, composed of a mass of sharp-pointed peaks, crests, and obelisks. Great masses of snow, like glaciers, lie on the almost vertical sides per- petually, though they abruptly descend 45° or 50°. Huge fissures may be seen in these great masses of snow and ice, that may indicate slow movements downward. At any rate, we may call them remnants of the old glaciers that once existed here in abundance and have left their traces on the surface everywhere. Numbers of little gem-like lakes are seen high up in the amphitheaters, sometimes even above timber-line, reservoirs for the water that melts from these old gla- cier-remnants. A fact worthy of note here is the vast quantities of dead grasshoppers that are found on these masses of snow. The quantity may be estimated by bushels, and the bears frequent these high places in search of them for food. At certain seasons of the year the air is filled with grasshop- pers, apparently flying in every direction, to a height far beyond our, vision. It is probable that they become chilled in flying over these high mountain-peaks, and, dropping down on the snow, perish. The Blue River range juts up against the south rim of the Middle Park, extending southward along the west side of the upper portion of Blue River. On the east side of Blue River, there is a long, rather high ridge, extending into the park, composed largely of Cretaceous shales with dikes of basalt i in great numbers. The basalt occurs on the sum- mit and crops out of the sides in many places. Far in the distance to the northeast is the Front or Colorado range, with Long’s Peak, and the intermediate group of high peaks. To the east, Torrey’s and Gray’s peaks are well shown, and to the southeast are the peaks around the Middle Park. ‘To the south is the Sawatch range with the Holy Cross in the foreground, and west of south, Snow Mass, Sopris, and other high peaks can be distinctly seen. The intermediate space is filled up with the sedimentary beds, of which the red beds cover by far the largestarea. The Blue River range trends about north and south, extending up so as to form the northern portion of the Parkrange. Looking to the west we ean seethe great mass of sedi- mentary beds inclining from the west side of the Blue River range and from the east side of the Holy Cross, and its associated peaks forming about midway a curious synelinal. The two forces have crushed the beds together. The sedimentary group here forms a belt from fifteen to twenty miles in width, expanding to a greater breadth to the west and northwest. To the northwest from Mount Powell we can look into Hgeria Park, a sort of elevated plateau or meadow, a beautiful park, though small, about five miles in diameter and nearly. circular in shape. North of the middle park but not very distinctly visible from Mount Powell, is the North Park. To the west, naypex.) GEOLOGY—FROM ELK MOUNTAINS TO MIDDLE PARK. Cl just on the verge of the horizon, isa high range called the Elk Head - Mountains. Long, high ridges rising to the limit of perpetual snow may be seen far to the west, apparently composed of stratified rocks. Through these ridges the little streams have cut deep gorges as they flow westward to the Colorado River. These gorges must present most excellent sections of strata to the geologist. Here and there we can see the whitish marls and sands of the modern lake-deposits on the upturned edges of the variegated beds. In the deep basin of the Middle Park these Pliocene or Post-pliocene deposits are quite conspicuous. The rocks which compose the great mass of the Blue range may be called granites. Much of the rock is banded and strati- fied, but the older portions are massive and solid, that is, the lines of bedding are wauting. From Mount Powell we descended the west side of the mountain again, and returned to Hagle River. The evidence of the former ex- istence of a large glacier extending up into the mountains in various directions and filling up the valley of the little stream is quite clear. The valley is oval in shape, and about four miles from the base of the mountain closes up into a narrow channel, in which are a number of morainal ridges. Above the ridges is a small lake one-fourth of a mile wide, which was undoubtedly formed by the glacier. The high ridges on both sides are covered thickly with rounded bowlders. Interstrati- fied with the red sandstones are some thin layers of limestone, in which are numerous fossils, Crinoids, Corals, Productus, &c., with other forms which are unmistakably of Carboniferous age. The dip is very slight, hardly more than 3° for several miles. The fallen timber is a great obstruction to traveling. Inthe autumn the sur- face becomes as dry as tinder, and the fires run over the country, destroying the life of the pinesas they stand. The winter and spring winds prostrate them in every direction, so that they sometimes form a net-work 5 or 6 feet high for many miles. As we descend Eagle River below the mouth of Roches Moutonnés Creek, the valley closes up for several miles, but expands out again to half a mile in width, with soft beds on both sides. High on the mount- ain-slopes are thick groves of poplar or quaking asp. A group of beds comes in on this stream about ten miles below the Roches Moutonnés Creek, 1,200 to 1,500 feet in thickness, which appears to be separate from the regular formations, apparently a partially fresh-water deposit, for in some thin layers of impure limestone were numerous small shells like Planorbis, and Physa, and the lower 400 feet are composed of very thinly laminated shales, while the upper portions are very gypsiferous, and might be called gypsiferous clays and marls. This group appears very abruptly, and continues down the river for a few miles, and then disappears as if it formed a sort of basin in the va- riegated group. Whatever may have been the origin of this curious gyp- Siferous group, it seems to be local, and: to le in the Carboniferous or between the Carboniferous and the Triassic. We traveled along the valley so rapidly that I could only examine the immediate channel of the river; and I here present these hasty observations to call attention to the group. The whole district will be studied in detail during the summer of 1874. Above the gypsiferous group is a series of the brick-red beds, 500 feet or more, and still above a series of variegated beds 400 to 500 feet thick. In the lower portion of the gypsiferous group, in a bed of limestone, I found a species of Productus and a Spirifer, all Carboniferous forms. Above the gypsiferous group, and just below the brick-red beds, f 78 GEOLOGICAL SURVEY OF THE TERRITORIES. found, still lower down the river, in a bed of blue limestone, an Orbicu- la, plainly a Carboniferous specimen. The evidence seems clear that all the rocks on Eagle River are of Carboniferousage. As wecontinue down the Eagle River to the north- west, toward its junction with the Grand, there is a very curious twist in the bed, which can hardly be described except by an illustration. Hitherto the great mass of the strata has been inclining from the range of the Holy Cross, but here we seem to have met the force which acted from the direction of the Blue River range, by which the dip is suddenly changed by a remarkable cause from a northeast to a north- west direction, and while some portions of the group incline at an angle of not more than 20°, others stand nearly vertical, and in some in- stances have passed a vertical. We have here exposed in Eagle River a series of curiously-variegated beds, at least 4,000 feet in thickness, of Carboniferous age; above them 1,200 to 1,500 feat of brick-red sand- stones and clays, probably Triassic, and above them 200 feet or more of Jurassic age; then overlaid by a heavy bed of quartzite, 150 feet thick, undoubtedly No. 1, or Dakota group. Above the last are the black plastic clays of No. 2, in a nearly horizontal position. Overlying the clays is a bed of dark limestone filled with fossils, as Inoceramus, Ostrea congesta, and other forms of mollusks, with abundant fish-remains, but so broken that scarcely a good specimen couid be found. At this point we left Eagle River and struck across the country north- northeast through a synclinal depression, or a sort of basin, from five to eight miles in diameter, with the quartzites of the Dakota group rising up with a gentle slope on all sides, while the high divide on the north side of Eagle River is elevated by the dikes of basalt so as to form a rim connecting the east and west sides of the basin. Hagle River, be- low the point where we left it, just before it joins the main stream, cuts through No: 1 and a great thickness of the brick-red beds, which are elevated so as to show a general dip east and northeast, while on the opposite side of the synclinal the dip is south and southwest. The quartzite bed of the Dakota group gives character to the slopes as well as to the topography of this immediate region. The strata in- clining to the north and northeast has been elevated by the Holy Cross range, while the almost vertical. beds on the opposite side of the syn- clinal have been lifted to their present chaotic position by two forces ; one acting from the Blue River range, and the other arising from the outflow of igneous matter in the form of dikes. We may state, in gen- eral terms, that in the Middle Park and its surroundings the complica- tions in the positions of the strata of the various formations have been produced by igneous eruptions. The terraces along Eagle River ought to receive a passing notice. There are usually two of them. Varying from 10 feet to 50 or 100 feet above the river, usually covered with rounded bowlders, there is a good thickness of the drift on them, but the underlying strata of the original formations are everywhere exposed, showing that the valley is for the most part one of erosion. » Not unfrequently the river cuts a narrow channel across the upturned edges of the basis rocks, which, in this way, may be traced across the valley from bluff to bluff. The height. of the divide overlooking Hagle River is 1,450 feet above the river-bed, and this may be taken as the ageregate thickness of the entire Cretaceous group in this basin. All the divisions appear to be represented ; and what we usually regarded as No. 5 I estimated as 400 to 500 feet thick, composed of brown arena- ceous Shales, with irregular beds of sandstone, varying from a few feet FROM ELK MOUNTAINS TO MIDDLE PARK. 19 HAYDEN. ] GEOLOGY to 100 or 150 feet. In No.5 area great abundance of fossils of the genera Inoceramus, Baculites, Ammonites, Sc. The surface of the entire country is exceedingly rugged, and the high ridges, underlaid with No. 5 or No. 1, contrast curiously by the lux- uriance of vegetation with the barren, sage-covered surface of the black plastic clays of Nos. 2 and 4. The high ridges of the divide are covered with vesicular basalt, much of which is spongy, like lava. The dikes have a trend about 20° south of east, and as they are very numer- ous and are nearly parallel, resemble waves of the sea as they extend along the surface in more or less elevated ridges. These basaltic ridges are sometimes continuous for several miles, but they usually break up into fragments, yet still preserving about the same trend. As we travel from Hagle River to the valley of the Blue, the surface is covered to a greater or less extent with loose fragments of modern basalt, varying much in texture and color. The country reminded me very much of portions of the Yellowstone Valley in Montana. As we descend into the valley of the Blue, below the junction of the Grand, we can see that the high ridges on either side are capped with basalt, but underneath are the black clays of the Cretaceous. A great thickness of the sedimentary beds cover the country, but they are literally riddled with dikes, and the strata are thrown into complete chaos. On the north side of the Blue River, about fifteen miles below the junction of the Grand, are several long mesa-like ridges that rise 1,000 to 2,000 feet above the river-bottom, and apparently incline from an extension of the Blue River range along the west side of Middle Park.. These mesas present a structure too complicated for our limited time, but the entire mass seems to have been lifted up nearly vertically, pro- ducing great faults, so that on the south side the variegated beds which lie beneath the Cretaceous group were tipped up at the base in a verti- cal position, and sometimes 15° to 20° past a vertical. These mesas, capped with basalt, slope southwest 5° to 15°. In the sides of these mesas several beds of basalt are shown, varying from 4 to 40 feet in thickness, with a layer of volcanic tuff intervening. To work out the complicated structure of this most interesting region | would require the diligent labor of a season, and I can in this report only noticé it in general terms. There are, however, most abundant illustrations of the action of the two forces, one of which, long contin- ued and uniform, produced the anticlinals which are continually inter- rupted or thrown into confusion by the eruption of voleanic matter. Along the Grand and Blue Rivers, on the west of the Middle Park, are three quite important cafions, the Lower, Middle, and Upper. The Lower Cafion is formed by the passage of the Blue River at right-angles through a high ridge of feldspathic gneiss, with walls 1,200 feet high. There seem to be a number of these granite uplifts, extending with a nearly north and south trend across the park. The most western one rises about 1,200 to 1,500 feet above the bed of the river. From either side of these granite nuclei the sedimentary beds incline at various angles. The Middle Cafion is about three miles below the junction of the Grand River with the Blue, and is much the most extensive. The Lower Canon is only about one-third of a mile in length, while the Middle Cafon is full three miles long. The anticlinal ridge, as it might be called, is really an extension north- | ward of the Blue River range, and forms the west rim of the Middle Park. The slopes on the east side are all gentle, and are mostly com- posed of the quartzites of the Dakota group. So far as I could ascer- 80 GEOLOGICAL SURVEY OF THE TERRITORIES. tain, the quartzites rest directly on the granite nucleus and flex over the sides like a gently sloping roof. In the interval between the western and middle ridges there are several small ridges or uplifts of the gran- ites that produced small anticlinals and synclinals. There is one about two miles above the Lower Caiion and between it and the Middle Canon ; the variegated beds form a well-marked synclinal. Scattered around among the uplifted masses are depressions or basin-like valleys that are filled with the modern lake-deposits. In the gorge of a little branch that flows into the Grand from the south side, just above the Lower Cafion, there is a bluff-exposure of these modern deposits, mostly of a deep drab or flesh color, and sometimes are 50 feet high, with three layers of sandstone each 4 to 6 feet in thickness; at another local- ity 200 to 300 feet in thickness of these modern deposits, with a bed of basalt near the summit. Like the modern lake-deposits in the valley of the Yellowstone, they are very often capped with a basaltic layer. There is no doubt that dur- ing the existence of the Pliocene or Post-pliocene lakes there were re- peated eruptions of basalt, and probably there were hot springs which dissolved the silica and feldspar, thus producing the fine materials which have entered largely into the composition of these deposits. Be- tween the west ridge and the middle ridge there is an interval of about five miles. In this interval the variegated beds seem to have thinned out much from the west toward the east, and here they rest directly on the gran- ites. I call them. variegated beds from the great variety of colors they present. Whether they be Jurassic or Triassic age, or both, I could not tell. I only know that the well-marked Cretaceous beds are immediately above them. Immediately below the Middle Cation the Grand River flows for about three miles through what I would eall a valley of depression; the river cuts down into the granite base, and at the lower portion of the little basin forms a narrow canon with ver- tical sides or walls 50 feet high, while on either side granite hills rise 1,000 to 15,000 feet above. In the basin and resting upon this granite rock, but inclining at various angles, is a considerable thickness of the variegated group. Neither on the middle ridge nor in the valley of the Blue or the Grand, east of this point, did we observe any of these red beds, and the quartz- ites of the Dakota group rested directly on the granites. The entire disappearance of from 4,000 to 6,000 feet of sedimentary beds within so short a distance is certainly worthy of note. I have mentioned the parallel ridges that extend across the Middle Park in a nearly north and south direction, through which the Grand River has carved out deep cafions. On the west side of Blue River there is one important ridge rather convex in form, with a granitic nucleus. On the west side, near the pass that leads over into the valley of the Blue River, is a singular mass of basalt, with a form so peculiar as to readily attract the atten- tion of the traveler. It has much the shape of a huge steamboat. The materials were effused in such a manner as to form a series of thin lay- ers, flexed upward at each end, dish-like, with vertical sides 100 feet or more. These dishes in the granite nucleus are very common. In some instances the effusion of the basalt has changed the adjacent rocks, and in many eases it has flowed out like water from a spring, producing no change, but simply covering the surface for a greater or less distance with the igneousrocks. Onthe high summits of the surrounding ridges caps of basalt are common, giving them a partial table-like form. HAYDEN. ] GEOLCGY—MIDDLE PARK. 81 As we descended the mountain-ridge into the valley of the Blue, soon after passing the summit, we found the quartzites of the Dakota group apparently resting directly on the schists, and as we descend the gently sloping east side we here find sections of the full series of Cretaceous beds inclining not more than from 5° to 8°. As far as the eye could reach, from Mount Powell northward, the quartzites of the Dakota group laid over the east side of the ridge like the roof of a house. On the east side of the Blue there is a high Cretaceous ridge, mostly above the Dakota group, penetrated in numerous places by dikes, out of which ereat masses of basalt have flowed over the surface. The river itself for a distance of nearly 20 miles to its junction with the Grand flows over the black-clay shales of No. 4 and the dark-gray calcareous shales of No. 3, following a monoclinal interval. The terraces along the Blue River are quite noticeable. There are two principal ones, but these not unfrequently break up for short distances into several smaller ones. On the east side of the Blue River, near the junction with the Grand, and on the north side of the Grand, are isolated, low hills of granitic schists, around the sides of which the Cretaceous clays are elevated at moderate angles. As we ascend Grand River even the Dakota group thins out to a considerable extent, so that in some localities it is quite probable that the entire Cre- taceous group is wanting, and the lignitic strata repose on the schists. Above the junction of the Muddy the valley of the Grand reveals a good thickness of the lake-deposits. The terraces are also quite well marked, rising sometimes 80 to 100 feet above the bed of the river. MIDDLE PARK. The geological structure of the Middle Park has been so carefully studied by Mr. Marvine that I will pass over it very briefly. The geol- ogy is very complicated and of great interest; but in order that it may be clearly understood, it must be presented in great detail with illus- trations. This Mr. Marvine was abletodo. In 1869 I spent a few days in the park, and the results form one of the chapters in my annual re- port of that season. The variegated beds occur in the southwest portion of the park near Frazer River, beneath the Cretaceous group, and though far less con- spicuous than on the east side of the front range, are undoubtedly of Jurassic age. Near the hot springs there is a high hill, sometimes called Mount Bross, to which I directed attention in 1869. It is composed almost entirely of beds of the Lignitic group, 1,800 to 2,000 feet high above Grand River. From this hill we obtained a great variety of fossil-leaves characteristic of the Lignitic group. From this group in the Middle Park Mr. Lesqureux has identified Sapindus angustifolius, Staphylea acuminata, Planera longi- folia, Rhus drymeja, Glyptostrobus europaeus, Sequoia angustifolia, Fraxinus preedicta, Ulmus tenuinervis, Myrica acuminata, Ilex sphenophylla, Pierocarya americana, Rhus Haydeni, Myrica latiloba. Of the above- mentioned species S. augustifolia and Planera longifolia occur in ac- knowledged Tertiary strata near Elko Station, Nevada, and the former is also found in the South Park. Ilex sphenophylla occurs at Green River. The Clyptostrobus europaeus is found at Fort Union and in the arctic regions, aud is regarded as a Miocene species. So far as we can judge from the fossil-plants, this great series of strata in the Middle Park must belong to the Lignitic group, and is probably of Lower Tertiary age. On the north side of the Grand River, about the source of Trouble- 66S 82 GEOLOGICAL SURVEY OF THE TERRITORIES. ’ some and Willow Creeks, and between those two streams, the aggregate thickness of the Lignitic group cannot be less than 4,000 feet, and it is probably greater even than that. This is made up of sandstones of various texture with partings of clay, the entire mass having the dark, somber hue which characterizes the same group about the sources of the Missouri and Yellowstone Rivers. These beds have been so thoroughly studied by Mr. Marvine that I allude to them in this connection simply to call attention to the possi- bility that they did not form a connection originally with the same group on the east side of the range. The differences in thickness and in lithological character of all the sedimentary groups in the Middle Park, as well as their position, ,indicate that a portion of the Front range was elevated above the sea, thus cutting off this portion from the east side. Although the peculiar flora of the Lignitic period is very abundant in the Middle Park series, no beds of coal have been observed as yet, and in this respect they offer a marked difference. [have hitherto been disposed, from the original evidence shown at the northward, to regard the physical connection of this great Lignitic group on opposite sides of the mountain-ranges as proven, but there is some doubt on this point, and I now await further proof. REPORT OF ARCH. R. MARVINE, ASSISTANT GEOLOGIST DIRECT- ING THE MIDDLE PARK DIVISION. WASHINGTON, D. C., June 19, 1874. Siz: I submit herewith my report on the geology of the region trav- ersed. by the Northern or Middle Park division of the United States Geological and Geographical Survey of the Territories during the work- ing season of 1873. ; The field was taken May 29 with a party proper consisting, beside my- self, of Mr. G. R. Bechler, topographer; Mr. 8. B. Ladd, assistant topog- rapher; Sheppard Madeva and Robert Mitchell, packers, and George Bowline, cook; the transportation of our baggage being effected by means of a train of seven pack-mules. The methods of work were pre- cisely the same as in the other parties. Messrs. Gardner, Holmes, and Chittenden accompanied the party during the first month of the season, when the base-line was measured, and the movements so directed that the stations forming the first expansion of the primary triangulation could be conveniently visited. When Mr. Gardner left to continue this work, and Messrs. Chittenden and Holmes to join their respective par- ties then entering the field, Messrs. Enos T. Luce and 8. H. Nealy, gen- eral assistants, joined me, and the work was directed solely to serve the purposes of the detail topography and geology. ‘The continental divide over into the Middle Park was permanently crossed on September 2, scon after which Messrs. Luce and Nealy returned, reducing the party to its original number. In mid-October the breaking up of the season rendered it judicious to return over the mountains before permanently closed with snow, and on the 15th of the month we turned homeward, leaving a portion of the work in the vicinity of Breckinridge incom- plete. Being on the route to our work of the coming season, it can then be conveniently and speedily finished. The area actually examined during this interval of time, so that both its topography and geology can be mapped in considerable detail, is. nearly four thousand square miles, which, by material obtained from the jand-surveys upon the plains, has been extended eastward to include a total area of over fifty-six hundred square miles. This area is approxi- mately in the form of a rectangular belt sixty miles wide north and south, the eastern end resting on the western border of the great plains and including Denver City, and extending westward over the main chain of the Rocky Mountains, and across the Middle Park to the Park range - bordering the latter on the west. West of the plains there are no large level areas to facilitate rapidity of work, while much of the zone of mountain country bordering the main divide on the east not only pre- sents peculiar difficulties to rapid and at the same time accurate map- ping, but it is comparatively thickly settled, and demanded much more time for its completion than equal areas elsewhere. Mr. Bechler’s map 84 GEOLOGICAL SURVEY OF THE TERRITORIES. of the whole region, on a scale of two miles to an inch, and in 200 feet approximate contours, is now very nearly finished. Geologically the area surveyed divides itself into three natural dis- tricts: first, the sedimentary rocks of the plains; second, the great system of archean metamorphic schists and granites forming the Front and Park ranges, with some minor areas; and third, the sedimentary rocks of the Middle Park. : On account of the greater length of time spent upon the, eastern mountain-zone, a very great number of observations were made upon the archean rocks composing it, and a fair insight gained of their gen- eral characters. Though the sedimentary rocks were much more rapidly passed over, yet their comparative simplicity of structure and persist- ence of lithological characters rendered them easier of study, and has permitted of my plotting all my observations among them on the drain- age map furnished me by Mr. Bechler early in the spring, and of my completing my chapters upon them to the full extent of my observa- tions. I may say here that during the season the sedimentary rocks of the plains were avoided as much as ‘possible, and preference given to the less-known archeean rocks of the adjaeent mountains, with the expecta- tion that when the autumn snows should have driven us from the latter work could still be prosecuted among the former, an expectation not re- alized because of the early return of the party to the Hast. In order to make my scattered observations among these sedimentaries more con- nected and useful I have theught it desirable, therefore, to utilize such other published observations upon them as I have been able to find, chiefly from your own reports, giving credit and references in their proper places. Notwithstanding the special attention given to the archean rocks, their far greater complexity requires that before the large number of disconnected observations made among them can be properly discussed and correct results drawn from them, they should first be carefully plotted on the fipished topographical map. Since this is as yet impos- sible, I have been obliged to treat this subject—the most interesting one presented in the region in question—very briefly, simply giving the most general impressions received while in the field, and without a proper digest of the notes at hand. Accompanying the report I submit aiso a provisional geological map, colored on a photographic copy of the drainage map of the district, as accurately as it can be done on a map expressing no topographical feat- ures except the streams, and which will serve for office use until the completion of the final map. The report which Mr. Ladd makes to you separately on the means of communication, elevations, distribution of timber and agricultural lands, and population within the district, will greatly supplement the first chapter of my report, and completes, I believe, the record which is to appear in this annual report of the material gathered by the Middle Park division during the past season. Besides acknowledging cordial co-operation from all members of the party, I wish also to refer to the many services volunteered by Messrs. Luce and Nealy while attached toit. For aid in my own specialty L wish to particularly recognize the serv- ices of Mr. Holmes, Mr. Ladd, and George Bowline in the field, and of Mr. Ladd and Mr. Holmes in the office, for to them are chiefly due the sections, maps, and views accompanying this report. To Mr. Berthoud, Lae GEOLOGY—NATURAL DIVISIONS. 85 of Golden City, is also due much information about the coal-openings of the Territory. Rapid preparation of a summer’s observations, together with absence during publication, must atone for many errors which will inevitably eceur. Very respectfully, yours, ARCH. R. MARVINE, Assistant Geologist, Directing the Middle Park Division. Dr. F. V. HAYDEN, In Charge of the United States Geological and Ge ographical Survey of the Territories. CHAPTER I. AREA, NATURAL DIVISIONS, AND PRINCIPAL TOPOGRAPHICAL FEATURES. The territory embraced by the survey of the Northern or Middle Park division during the summer of 1873 is included between the parallels of 09° 30/ and 40° 20/ north latitude, and the meridians of 104° 45’ and 106° 30’ west longitude. It forms, therefore, a rectangular area, which has a width north and south of about sixty miles, a length east and west of about ninety-three miles, and which contains nearly five thousand six hundred square miles. ‘This area may be conveniently located by refer- ence to the Union Pacific Railroad, which passes about fifty miles north of its northern border, on which side it is cnneEly joined by a similar area of the fortieth-parallel survey. The eastern portion of this parallelogram rests upon the western border of the great plains which extend uninterruptedly from the Mississippi and Missouri Rivers, and ineludes some of the most thickly settled por- tions of Colorado. Denver City, and many smaller towns, with their railway connections and surrounding agricultural regions, are here sit- uated. The middle portion of the district is traversed north and south by one of the highest portions of the main continental divide, with, on either hand of the great crest, the accompanying zone of mountain country, which contains nearly all of the more important metal-mines of the Ter- ritory. The western portion of the area is chiefly occupied by the several depressions which together make up the Middle Park, with their sepa- rating ridges, and is limited upon the extreme west by the Park range. A strip along the seuthern edge of this portion was not completed by this season’s work. Regarding. its broadest topographical features, therefore, this rectangle may be considered as dividing itself naturally into three portions, which we may conveniently designate as the eastern portion, or the plains, the middle portion, or the mountains, and the western portion, or the park. So far as drainage alone goes, the dis- trict as a whole may be regarded as being separated by the nearly north and south crest of the main mountain- divide into two very nearly equal east and west portions, in each of which the drainage system is quite simple. The main artery npon the east is the South Platte River, which flows diagonally northward and eastward across the plains portion of the district. All the streams rising at the eastern base of the main central 86 GEOLOGICAL SURVEY OF THE TERRITORIES, ridge flow in a general eastward direction, joining here and there, and within the limits of the district find their way into the South Platte. In the western half of the district the drainage is somewhat different, though still very simple. The main divide not only passes through the center of the district, but, at the north, turns westward along its northern border, while at the south it also turns westward, trending along the southern border, thus inclosing the park on the north, east, and south sides. From all sides of this natural rim the streams flow inward to join the Grand River, which flows east and west through.the middle of the system, forming its main artery. All the waters thus find their way out of this basin through the single cation which the Grand has cut across the Park range at about its middle point, and flow on westward to join the Colorado River and the Pacific Ocean. Upon the north the North Park gives rise to the North Platte; upon the south the South Park gives rise to the South Platte, and both flowing eastward their united waters finally join the Missouri. The Middle Park is thus inclosed by a great eastward loop of the main continental divide, and it forms the © easternmost point north of Mexico at which waters flowing into the Pa- cific take their rise. PRINCIPAL TOPOGRAPHICAL FEATURES—MAIN DIVIDE. The crest of the main divide crosses the northern line of the district in longitude 105° 45’ west, or at about midway of its length. From this point its trend for ten miles is southeast to near Long’s Peak, where it turns directly southward, but with an undulating course, a distance of sixteen miles, to Arapahoe Peak. Along this line, the range is an exceedingly formidable one, and presents all the features of mountains composed of granitic and schistose rocks. The eastern face of the crest presents an almost continuous line of amphitheaters and gorges rimmed with precipitous walls, which rise to a serrated crest of which many points reach an altitude of between thirteen and fourteen thousand feet above sea-level, while not a single pass exists except such as the most expert mountaineer might with difficulty ascend. Some of the higher points exist as eastern spurs somewhat detached from the main ridge ; such are Long’s Peak, (14,270 feet,) Mount Audubon, (13,190 feet,) and Smith’s Peak, (13,090 feet,) on either side of which are the deep-cut gorges, reaching past them to the steep cliffs beyond, at the bases of which the banks of everlasting snow are constantly eating their way farther and farther into the range. Upon the northeast side of Long’s Peak, forming its very face, IS a sheer, almost perpendicular, cliff, over 3,000 feet in “the clear, reaching from the mountain-summit to the timber- line, the grandest wall of rock imaginable. The western side of the main divide does not present so well-defined aridge. Instead, it is lined by a zone of high mountains, from five to- ten miles across, which falls abruptly, though not precipitously, to the great trough-like valley of the Upper Grand. It is cut by profound cafons draining into the latter. Upon the southwest, this rngged mass is sharply limited by the East Fork of the Grand, while Arapahoe Peak forms its southern apex. From Arapahoe, for twelve miles directly south to James Peak, the topography changes. The crest presents a very uniform ridge rising but little above timber-line, and for five miles near the southern portion scarcely varying 200 feet in altitude. As at the north, the eastern face of this ridge is precipitous, falling in great Be te GEOLOGY—TOPOGRAPHICAL FEATURES. 87 cliffs to a series of amphitheaters which make up the front, each with its bank of snow lying up against the base of its rocky walls. Some of the rounded spurs reaching eastward between these amphitheaters afford a means of access to the ridge. Thus, at the north end of this depressed region, and directly at the base of Arapahoe Peak, is the Caribou Pass, as yet not well opened, and unpromising; about midway of its length is the Boulder or Rollinsville Pass, (about 11,400 feet,) now reached by a road over which wagons can pass; while at its southern end, below the walls of James Peak, is the James Peak trail, a wagon- road from Central City reaching as yet only to the base of the Peak.* The western slope from this ridge is of a very different character from the eastern slope. Though of course having many of the characteris- tics of a rugged mountain region, yet, as compared with the east slope, it has no precipitous front, but its massive westward spurs fall in rounded, gently-molded slopes, not separated by deep cations, to the basin-like depression of the Frazier River. The line of separation be- - tween this region and the rugged mountain area at the north is exceed- ao ingly sharp, and is occupied by the Hast Fork of the Grand. Rising from the canon of the latter on the north and east is the maze of peaks and rugged ridges, separated by profound gorges and amphitheaters, which drain into the Hast Fork. The south bank of the cation, however, is cut by no important side gorge, but only by local gulches; and rising up its steep but even slope the summit ridge is found to be a compara- tively smooth table or plateau, sloping westward, with gentle eleva- tions here and there. All these massive spurs to the south have these more gentle slopes, and are remarkably similar in general section. At James Peak, (13,283 feet,) there rises another group of rugged mountain points, among which are Mount Parry and Mount Flora. Here the divide bends more and more westward, and after making a southing of about five miles and a westing of about ten miles, it again swings southward for seven or eight miles and then southeastward for about an equal distance, taking the famous Gray and Torrey Peaks on the way, the former being 14,340 feet high, and the latter but about 5 feet lower. Though from here the drainage divide turns again westward and south- ward, passing into the South Park, or middle division of the survey, yet the higher ridge runs eastward asa great spur which culminates in Mount Evans, a great massive mountain, which rivals Gray and Torrey in altitude. From James around to Evans is thus a great western loop, inclosing the headwaters of Clear Creek. It represents, also, a high mountain region, not as a whole, perhaps, so rugged as the Long’s Peak mass, but more extensive, spread out, and diversified in its character, yet possessing some of the grandest mountain features and most im- pressive scenery. After leaving the James and Parry groups of peaks, and passing westward along the northern side of the loop, the ridge becomes less rugged, somewhat resembling that north of James Peak, while some of the separating valleys are cut to the timber-line. One of these forms Berthoud’s Pass, (11,349 feet, Parry,) the summit of which is not much more than seven miles from Empire City, on the North Fork of South Clear Creek, and over which a wagon-road exists, and a narrow-gauge railway-line has actually been surveyed over to the South Forks of the Frazer River. The break next to Berthoud’s Pass is called Vasquez Pass, (about 11,500 feet.) The mountain spurs descending northward to the Frazer here pre- _ *For passes and means of communication generally, with information given more in detail than here, the reader is referred to the report of Mr. 8. B. Ladd. 88 GEOLOGICAL SURVEY OF THE TERRITORIES. sent the same smooth and rounded contours as those on the east side of the Frazer basin. From the northeast corner of the loop a high spur runs out, separating the Williams and Frazer drainage, and culminat- ing in Mount Byers, (12,778 feet,) one of the most commanding points of all the Park region, at the north. The western side of the loop is a rugged mountain ridge, with, I be- lieve, a difficult pass, called Jones’s Trail, across to the headwaters of - Williams River. The descent to the main valley of the latter, along the west side of this loop, and from the Mount Byers ridge, is in. great massive spurs, descending rather abruptly, but still quite evenly, and cut by deep gorges. The Gray’s Peak ridge is much the same, rugged and grand, yet, on the western side, with an obvious tendency in the spurs to a general plateau-like area, though it is almost obliterated by the many caiions. Directly beside the peak, passing almost over its top, is a fair trail for animals to pass, while a few miles to the east a wagon- road is built, crossing the range at the Argentine Pass at an altitude of about 13,200 feet, and connecting Georgetown with Montezuma and the other mining towns upon the headwaters of the Blue River. Nearer Mount Evans a trail crosses the Evans spur from Georgetown over into the South Park. ae Eastward from Evans the spur is continued by a long ridge-like line of hills, reaching nearly to the plains, and separating the waters which flow southward into the South Platte, and without my district, from those which flow eastward and into it. It forms, with the course of the main divide upon the west, a natural southern boundary of the district. PRINCIPAL TOPOGRAPHICAL FEATURES OF THE HASTERN SLOPH. The crest of the main divide as thus traced may be considered as pre- senting, as a whole, a flat convexity to the east, on which side its prin- cipal characteristic is abrupt slopes, usually in high precipices, sur- rounding profound amphitheaters. Extending eastward from these first abrupt slopes is a zone of mountain country which is narrowest at about the center of the district, where it extends about seventeen miles east from the main crest, but widening at the north and south borders of the district to nearly thirty miles. ‘The eastern face of this zone thus presents a flat concavity to the east, the general trend of which is north and south, while the depression westward in the center is about ten miles. This eastward border of the mountain-zone is exceedingly sharp and well defined, and all along it the mountain-spurs abruptly give way to the plains which stretch away uninterruptedly far to the east. This mountain-zone can in nowise be regarded as made up of dis- tinct ranges or a system of ridges, but as a unit in itself, having charac- teristics which hold very uniformly over nearly all its parts. From be- neath the precipitous crest, from all the gorges and amphitheaters atits base, flow innumerable streams which, after emerging from these upper cafions into the smoother highlands, soon collect into a few principal water-courses, generally uniting where they are not in deep canons. Flowing in a generally eastern course these gradually sink their chan- nels deeper and deeper into the rocks, the different main streams uniting their cafons here and there, and finally issue from their deep-cut gorges in the mountain-front to flow cut into the plains and to the Platte. hough over fourteen main branches may be considered as rising within the fastnesses of the main crest, their united waters break through 2 MARVINE.] GEOLOGY——-TOPOGRAPHICAL FEATURES. 89 the mountain-front in only seven points, while uniting still further in the plains, but four principal streams reach the Platte. This is not including the many streams which rise in the mountains east of the crest, some of which unite with the main streams, while others break in minor cafions from the mountains; while still others rise independently in the plains, forming subordinate branches of the Platte. Of the first class—thcse rising at the main crest—may be enumerated, commencing at the north, The Big Thompson, North, Middle, and South — Saint Vrains, Jim Creek, North, Middle, and South Boulder Creeks, North Clear Creek, Fali River, North and South Forks of South Clear Creek, Chicago Creek, and Bear River. Of the minor mountain-streams, those rising east of the crest, there are, likewise commencing at the north, the Little Thompson, Left-Hand Creek, Four-Mile Creek, Coal Creek, Raiston Creek, and Turkey Creek. Those that issue from the mountains are as follows: The Big Thompson, Little Thompson, the united Saint Vrains, the nnited Jim and Left-Hand Creeks, united Four- Mile and North and Middle Boulder, the South Boulder, Coal Creek, Ralston Creek, the united Clear and Chicago Creeks, Bear and Turkey Creeks; while the united Thompsons, the united Saint Vrains and Boul- ders, the united Ralston and Clear Creeks, and the united Bear and Tur- - key Creeks, or only four in ail, join the Platte. The tendency of these cross-cutting streams is to throw this eastern mountain-area into east and west ridges. These ridges. however, are seldom sharp, but massive, and rather thai. striking one as a system of ridges it impresses one as a system of deep-cut river-channels. Large, flat, park-like areas are numerous. In the northern two-thirds of this area, approximately parallel with and a few miles east of the first great slopes of the divide, is an irregular zone but little intersected with caions, and these not deep, and varying in altitude from 8,500 feet to 9,000 feet. It is a park region of rolling pine-sprinkled surfaces, with the high spurs rising on the west, and the mouths of the deep gorges which extend back to the range opening out upon it. In going east, as the canons cut deeper and deeper, the spurs perhaps not changing greatly in altitude, traveling north and south becomes almost impossi- ble. Throughout this region, however, except Lilly Mountain, just east of Long’s Peak, and Ralston Butte, between Ralston Creek and the South Boulder, there is a remarkable uniformity in the height of these ridges. Their tops are frequently quite level or gently rounded; while standing on one, the general level, which seems indicated in their tops, is very striking. South of Clear Creek, in approaching the Evans Ridge, this general summit-level is more irregular, the Squaw Chief and Bergen Park Mountain rising to exceptional heights ; yet, even here, large areas are frequently undulating or level, forming beautiful park- like regions; here usually occupied as farms or for pasturage. As viewed from the plains this general evenness of the teps of the ‘ foot- hills” is very striking. The majority of these ridges rise somewhat above 8,000 feet, while the plains along the eastern base of the moun- tains average not far from 5,600 or 6,000 feet. A few points along the face of the mountains rise higher than the country immediately in their rear, such as South Boulder and Golden Peaks, and Bear Creek, which stand close to the mountain edge. But as a whole the mountain-zone lying between the main divide aud the plains certainly impresses one as being, with a few exceptions, a region of very uniform or gently undulating general elevation, carved by the powers of erosion, perhaps partly glacial but mostly by streams, into a mountain area of which portions are exceedingly rugged. 90 GEOLOGICAL SURVEY OF THE TERRITORIES. PRINCIPAL TOPOGRAPHICAL FEATURES OF THE MIDDLE PARK. We have already seen how the branches of the Grand join it from the . northeast and south, like the rays of a great irregular leaf uniting with the parent stem. Along the main Grand, especially where joined by its tributaries, and following along some of the latter, are flat, open and treeless areas, which may be considered as forming the Middle Park proper. The ridges separating these tributaries are mostly well defined, some reaching altitudes of from 2,000 to 4,000 feet above the adjoining streams. These are mostly of sedimentary rocks, and quite different in character from the mountains of harder metamorphic rocks forming the main range. The Middle Park thus differs from both the North and South Parks on either hand, which are much better defined, large, basin-like areas less broken up by local ranges. Indeed, the Middle Park is a sort of accidental middle ground between the tio. The more important geo- logical dividing line between the North and South Parks is the great fold which causes the massive spur of metamorphic rock west of the Gray Peak mass, joining it with the Park range, though cut through by - the Blue. Between the Middle and North Park no such profound 2zo0- logical fact exists; there is no folding whatever, but the divide has been determined by the masses of hard ertiptive rocks which have here found vent and protected the softer rocks below from erosion. Indeed, it is just possible that the drainage of the Middle Park once had its cutlet into the North Park. In speaking of the more special topographical features of the Middle Park region, those portions adjacent to the high eastern ridge have already been referred to. Such is the rugged, canon-cut mountain area west of Long’s Peak, separated by the East Fork of the Grand from the more gently-contoured massive spurs to the south, which swing around with the main ridge from Arapahoe, through the James Peak group to Mount Byers, inclosing on the east, south, ‘and west sides, and partially on the north, the basin-like drainage- area of the Frazier. The latter river, aiter collecting the surrounding waters, escapes from this basin by a cation carved through about six miles of the low northern por- tion of the surrounding granite, and enters the basin of the Graad.. The main fork of the Grand, before joined by the east fork, occupies a re- markably well-defined, trough-like valley, trending directly north and south. Its headwaters rise in the deep gorges separating the main range from the high southern end of the Medicine Bow Mountains, whose northern extension forms such a symmetrical eastern border to the North Park. But where it crosses the north line of the district the V form has changed to the U form, with a comparatively flat bottom, between one or two miles broad, while the ends of the massive spurs forming its sides rise abruptly, but in rather smooth curves, on either hand. The eastern Hope of the valley retains its height and character all the way down to where joined by the East Fork, though cut by the many gorges draining the mountain area. The western slope, at the north, rises equally high and steep, though the crest being less distant it is cut by lesser cafions. Toward the south the top of the ridge becomes smoother in contour and gradually falls, finally giving way to the flattish region adjacent to the Grand. Here the latter turns westward and in a basin- like terraced area receives the waters of Willow Creek from the north and of the Frazier from the south. Passing on west it flows through Pe avine] GEOLOGY—TOPOGRAPHICAL FEATURES. ae two short rifts, or breaks in upturned strata, to the Hot Springs, which by their reputation and position virtually form the center of the Park. Here the stream enters a shallow cation three or four miles long, after which, for over fifteen miles, its course is through an extensive basin, much of the region along its lower course being river-bottom land. Williams River joins it from the south, while Corral and Troublesome Creeks flow into it from the north. The Muddy from the north and the Blue from the south, however, are the two principal tributaries of the Grand and join it at nearly the same point, just before it enters the cation through the Park range which carries it from the Park. This lowest point in the Park is about 7,180 feet above tide-water, while the Hot Springs are 7,700 feet, and Grand Lake approximately 8,150 feet above the same. The Williams River takes its rise in the deep western canons of the Clear Creek loop and the Mount Byers ridge. Issuing from this granite country it flows fer several miles through a wide flat basin tributary to that of the Lower Grand. The Mount Byers ridge extends from the base of that mountain as a quite straight and even-topped divide, separating the Frazier and Will- iams waters, and falls abruptly to the Grand at the Hot Springs. On the west side of the Williams Valley is the long, gentle, eastern slope of the symmetrical Williams River Mountains, which reach an altitude of about 11,400 feet, or nearly to the timber-line. On the north side of the Grand the Willow, Corral, and Troublesome Creeks drain an area which, being a geological unit, has uniform topo- graphical features. The culminating point of this mass is Park View Peak, near the northern line, 12,450 feet high, and directly overlooking the North Park. On either side of Park View Peak the divide between the two parks falls, the descent on the east to the headwaters of the Willow being about 2,620 feet to an excellent pass connecting the parks; a serrated region of not much greater height follows, and finally the abrupt rise to the Medicine-Bow Ridge. South of this line and parallel with the southern end of the latter ridge is a high, even- topped ridge, reaching to timber-line, which is quite surrounded by the eastern branches of Willow Creek. West of Park View, between the two Troublesome Creeks, the ridge is also depressed as on the east, but at the west fork it rises in a high lava-capped plateau, falling on the west to the Upper Muddy. ‘The next point of elevation of this mass is Corral Peak and White-Face Mountain, lying south of Park View, be- tween the Troublesome and Wiliow Creeks and north of the Hot Springs. These also are due to lava-caps protecting the softer horizon- tal sedimentary rocks below. Between all these points and extending south to the Hot Springs and across the Grand, somewhat, is a broken country chiefly made up of very numerous small spurs abutting against the streams, in all of. which the tendency is to a more or less definite terrace form, the broken terraces rising in steps to the higher lands beyond. The two forks of the Troublesome leave this region, where they join, and for the rest of the course the stream is in a flat basin country like that of the Lower Williams River, tributary to the Grand. This lower basin is separated by a low hilly divide from the Lower Muddy. The drainages of the Muddy and Blue alone remain to be referred to. Both lay at the eastern base of the Park range, and form very well de- fined valleys, trending in nearly the same general direction, and facing one another. The valley of the Upper Muddy is broad and shallow, presenting a strong contrast to most valleys of this country. Its gen- 92 GEOLOGICAL SURVEY OF THE TERRITORIES. eral features throughout are rolling-hills upon the sides, with low terrace- forms near the streams, the latter being cut by many side-ravines. All along upon the west is the great, rolling, wave-like ridge of the Park range, thickly timbered with pine. The broad head of the valley is a gentle rise over into the North Park, the divide between the two parks here losing its character of a defined ridge. On the east rises the high table- land | separating the valley from the Upper Troublesome, but this secon gives | way to the low ridge separating the lower waters of the two streams. Near the head of the valley is a prominent point called the Upper Muddy Butte. ‘Near its lower end, a similar isolated point, rising at the end of the low divide between the Muddy and Troublesome, and called the Lower Muddy Butte, narrows the valley locally before it enters the Grand. The general course of the valley may be vale as south 15° or 20° east. The valley of the Blue resembles that of the Muddy in the terrace feat- ures along the stream, but it is a narrower and more strongly defined valley, though by no means of the order of cations. For the lower twenty miles the general course of the valley is north 40° west. A few miles from the mouth - and on the east the Williams River Mountains commence torise. The western face, or that sloping to the Blue, is much steeper than the slope to the Williams River. It tends to a terrace — form, being of strata genily dipping east. The outline is very sym- metrical, rising in long slopes and gently-undulating top to a central point, and falling again in going south, but at twenty miles from the Grand River it abruptly joins a mountain region of a different class, namely, the granitic masses west of the Gray Peak group, which line all the remaining eastern side of the Upper Blue and quite change the char- acter of its valley. For nearly twenty miles south of the Grand the Park range on the west retains the same massive, evenly-rolling char- acter as at the north. But suddenly it rises to one of the most rugged — ridges conceivable. The backbone of this ridge is near its western side, and trends about north 40° east, but it is made up of numerous short eastern spurs, which abruptly but pretty uniformly descend along a line nearly par- allel with the main ridge. All these ridges are exceedingly sharp, and rise to a very uniform and general level; though the highest point, Mount Powell, is near the north end, and reaches an altitude of 13,285 feet. These sharp serrated ridges inclose a system of most profound gorges and amphitheaters. The main ridge is broken through by the valley of Ten-Mile Creek, but is immediately continued upon the south by a ridge running southward to the Mount Lincoln group. GENERAL GEOLOGICAL DIVISIONS. The three general divisions to which attention was first calied—the plains, the mountains, and the park—the more salient topographical feat- ures of which have just been described, are as natural geological divis- ions as they are topographical ones, nd will be considered in the three following chapters in the order mentioned. The one next fojlowing, Chapter II, in the sedimentary rocks east of the Front range, presents facts observed mostly along their western border, or near the mountains, together with observations gathered from other sources. Chapter I!1 briefly gives some general results of observations among the Archean rocks which form the mountains, and though this study was made prin- cipally upon the eastern mountain slope, yet the results appeared equally applicable to any other of the crystalline areas observed by the writer. Chapter IV deals with the general structure and distribution of the rocks of the Middle Park. eee 0 FEE I aye ig Pe ie 2 pp vention + eae age gt ms re c me 5 - « < l 1 oa Se ce ee Se A Sarees engi Avni = ee eee qs 4 = hi d f 4 a | mae Rates. , 4 ‘ 0 } s ot an eee os fn ne Cone Teens SESE fits } ‘\ { Cretaceous Jurassic Triassic ig —-- a ~ — Sec. if LITTLE THOMPSON. Gray shaly Limestone. — Compact Limestone |fusilin Black Shales and argil Limst. Black clay ecumbling Shales, some Slates ani light snuff Sandstones. Yellow Sandstone. Shaly- argil. Sandst Criimbling black clay Shalos. Brown Sandstone and crumbling Shales. Massive yellaw- and gray pilsious, Sandstone, ‘ap of principle mi — lag-back] —— Variegated Beds Soft, rather mass. Sandstanes. Soft red shaly Narudtstones with cherty limestone near base. Massive red Sandstones (Top of principle inner Hog - back’) Soft red shaly Sandstones | Soft massive rec. Sandst- CQoarse granite Sandst's and. Conglomerates, while to red Quartxites. Schists and. ! Granites. Archacan| ~~ Sec. 4. ; GOLDEN - crry. Seo Sco. 3. BEAR CANON. RALSTON CREEK. Lignitic | Formation. | | Yellowish shaly limest. Basaltic Lava- |__| etetie Frere =, No.3. Blue-gray » ” e . ae Sandstones ~ Light Gray compact limest. ROBE CRS: : and z Clays. g Covered (black $1 P y shales 3 vered (black shale) Light gray #1 Cretaceous . B Hard Silicious Sandstones. Limestones, 2 Lame, with hard blue shales. Clays zi z Sessa Silictous Sandstone or Grit. Wo. f- a massive, red and white Wariatarcee et Silictous shale SS | =< at Ee) Variegated sandy shales. ; eal oe Jurassic ~ Varcegated shales Variegated shales,postly argil! Red 3 RIE some Limestones- Reds. and Soft white massive Sandat- White Sandstanesyol?- Triassic. Varéegated shales, z & TET fd Soft, red. shaly Sandstones- pee iis eke i ls Cher ty Lumestac Beck sandy shale. Cherty Limestone wi ed i LALLA Yellaw Siticiaees jeuést® Explanation of Signs. Soft, red shaly Sandstoncs n\ ‘ O 4 t | Atassire Jef govtate Yellow; granular silictous Sandst) gritty but rather soft Hard massive red Sardstones wutercalated. shales, some conglomerates. High ridge of South. Boulder Peak : QEP“Y OF THE INTERIOR yreH! U.S.GEOLOGICAL asp GEOGRAPHICAL SUIVEY oF 1 FV. HAYDEN, Geotoaist im CHARGE Plate T DETAIL GEOLOGICAL SECTIO} OP THR Winebadded | Shaly Shales Slates white Sdlow |Z gry [= red LOWER SEDIMENTARY ROCKS FOUND ALONG THE EASTERN BASE or Tux ROCKY MOUNTAINS PROM THR LITTLE THOMPSON TOTHE SOUTH PLATTE. To accompany the Report of ARCH. R. MARVINE, MioOLE rank oisi08 lars Neale JOO feel (pan inch Triassic Se Cherty Limestone a 4 deme shales and Conglomerate. Sec. 6. SOUTH SIDE or SOUTH PLATTE. Dark shales. ry! shales. Rather massive Te =, and yellow Se I Shaly Sandstone, i wiegated red and green shales. { \ renaccors and argillaccous. Name weth while Sardstones- sual Jurasste Beds, Red arenaceous shales. 2 Red arenaceous shales. Soft red massire Sandstones. TeX [LEE Ura RROD) jeer raat ae = ee en 3 aceous Basaltte Lava Black argu: § | = Light gray sha Snes GEOLOGY—ROCKS EAST OF FRONT RANGE. 93 CHAPTER Il. THE SEDIMENTARY ROCKS EAST OF THE FRONT RANGE. Before presenting in detail the isolated facts which together make up our knowledge of the sedimentary rocks east of the mountains, and in order that these facts may be more readily understood and their rela- tions rendered apparent, it is desirable first to clearly understand cer- tain general geological features which underlie the whole country. These, though familiar to most geclogists, may be less so to the general reader, and I will endeavor to present them as simply as possible. Attention has already been called to the abruptness with which the mountains rise from the plains. The two types of topography which are separated by this sharp line ef demarkation are not more wholly distinct than are the two types of geology which it also separates. The recks of which the mountains are built, and which will be more fully treated in the following chapter, are granite, gneiss, schist, and al- lied rocks, which, in speaking of them as a class, it will be convenient to call Archean, or metamorphiec.* These metamorphic rocks are hard and crystalline in character, and, eecurring in large and comparatively irregular masses, present surface forms which are peculiar and very characteristic, so that one can sel- dom fail to recognize them even from a distance. Beneath the plains, however, there is found a class of rocks which possesses characteristics exactly the opposite of those just mentioned. They are neither so hard, nor are they crystalline; and instead of occur- ring in large and irregular masses, they lie in broad, flat sheets or strata, resting one above another, and stretching unbroken for miles in all di- rections. From the Mississippi and Missouri westward to the mount- ains stretches this great series of rocks, composed of layers of varying thickness of sandstones, limestones, shales, slates, and clays, which re- main much as they were when first laid down one after another in the bottom of the vast ocean which once existed here. Since this ocean was gradually drained off, the ceaseless ection of the rains and rivers has _ In places removed thousands of feet of these rocks, exposing beds which were once deeply buried, and in which we can occasionally find the re- mains of the shell-covered beings which still earlier lived and died upon the ocean-bottom, or the skeletons of the animals and plants which peo- pled the surrounding shores, and were swept by the ancient rivers out into the sea to be buried with the then forming sediments. It is but natural, therefore, that the surface characteristics of the great plains and rugged mountains should differ as they do. THE MOUNTAIN BORDER REGION. But let us examine the line along which these two opposite classes of rocks may be supposed to join. This line, we have already seen, trends *It has been found convenient, or rather necessary, for geologists to give definite names to certaii* groups of rocks. The accepted names of the more general divisions, in the order of their superposition or age, commencing with the oldest and proceeding to the most recent, are here given, those in small capitals occurring in the region under discussion ; : Pp 1. Anco H4sN—most ancient. 6. JURASSIC. 2. Silurian. 7. CRETACEOUS. 3. Devonian. Pliocene, 4, Carboniferous. 8. TertTrARyY< Miocene, 5. TRIASSIC. EOCENE. 9, Post-TrERTIARY and recent. 94 ' GEOLOGICAL SURVEY OF THE TERRITORIES. approximately north and south, passing about twenty miles west of Denver. Along it, the sedimentary rocks of the plains, instead of remaining horizontal, with their edges thus abutting against the steep faces of the mountain-rocks, like the sands along a rocky shore, are found to be all bent or folded more or less abruptly upward, their worn edges often rising into the air and presenting their scarred faces to the mountains. It becomes evident, therefore, that the sedimentary strata rest upon the rocks of the mountains, and that the latter, descending beneath the former, form the foundations on which they rest. This upturning of the sedimentary rocks along the mountains is illus- trated in a general way in the accompanying diagramatic sketch. Inasmuch as sediments laid down under water cannot end abruptly, itis apparent that these beds must once have been extended much farther up on the central mountain-mass than now, as indicated by the dotted lines. We will see later that after this folding of the rocks took place the level of the sea long stood above the present upturned edges of the sedi- mentary rocks, and that, as the iand through ages gradually emerged from the water, the wearing action of the slowly-retreating waves and of the usual subaerial erosion gradually removed all the higher portions of the strata, working back their edges, until they are left as we now find them. The surface of the country, as now presented to us, therefore, is due to the action of two causes: first, a folding of the rocks; second, erosion of those higher and ever-enlarging portions which slowly appeared above the gradually-retiring sea, and which may be progressing as rapidly now as the average erosien in the past. As there is always a variety in the hardness or other characters of the different beds, some will withstand erosion far less readily than others, and, wearing away faster than their harder neighbors, leave the latter rising as ridges above the general surface. ‘These ridges are cut through every few miles by the streams that flow down from the mountains, and while the immediate effect of these streams is to carve abrupt notches or cafions through the ridges, general surface-erosion tends to lower their adjacent ends. As seen from the east, therefore, these ridges appear to rise gradually out of the plain from either end to a nearly level center, in long gentle convex curves, and they Have thus earned for themselves the unfortunate name of Hog-backs. i But there are other beds to claim our attention a moment than those which have been upturned. The erosion which has molded the latter into their present forms has been much longer busy in the higher moun- tains, and much of the material worn from them since the folding of the rocks took place has been deposited in flat beds near the mountain’s base, often surrounding and quite covering the hog-back ridges. This border region, which varies from one to ten miles in width, may, then, be briefly described as one having abrupt mountain-masses rising boldly and ruggedly upon the one hand, and rolling plains stretching far past the eastern horizon upon the other, while along it the worn edges - of the harder upturned strata rise in long parallel ridges, the ends of which may fall either abruptly or in long gentle convex curves to the valleys of the cross-cutting mountain-streams, and which, rising gently from the east, fall in abrupt escarpments on the west to the trough-like valleys of softer beds between, in places all well exposed, and again so nearly covered with the accumulation of more recent material in hori- zontal beds that the higher ridges barely peep above the surface. In * MARVINE.] GEOLOGY—ROCKS EAST OF FRONT RANGE—TRIAS. 95 exceptional cases, harder beds may rise in ridges of abnormal height, or all may be leveled flat; the rocky fold may be more gentle or more abrupt, or complex; or the presence of volcanic products may add new features to the scene. Still the normal structure of the region remains the same. This region furnishes, then, the key to a knowledge of the rocks which underlie the plains, and, by selecting favorable localities for exposures, we may, in passing from the mountains eastward, pass in succession across the edges of the beds from the lowest to the uppermost. It would thus be found that a thickness of probably over 7,000 feet of sedimentary beds has partaken of the folding. These beds would seem to divide themselves naturally into four groups, which, so far as the presept burden of proof goes, are referable to tite following geological formations, commencing with the oldest: Triassic, Jurassic, Cretaceous, and Hocene(?). The upper part of this series, from the Middle Cretaceous up, being of comparatively softer beds, has been generally eroded back so far from the mountains, and to such a level and grass-covered sur- face, that exposures are few and scattered, requiring for study more time than could be given to them during the last summer. They have received special study from others, however, so that some general results can be given in the sequel. For the present we will confine our attention to the lower portions of these beds, the Triassic, Jurassic, and part of the Cretaceous. ; In describing these beds it will be found convenient to regard, first, their more detailed structural features, as lithological characters, age, &e.; and, second, their more general structural features, or the manner of their folding. ‘To illustrate the first class of facts Plate I has been prepared; and for the second, Plate II, (see end of chapter,) though in dealing with either class it will occasionally be found desirable to refer to both plates at once. On Plate I are gathered sections taken at six points along the zone of hog-backs, namely, commencing at the northern one, at Little Thomp- son Creek, Bear Caiion, Ralston Creek, Golden City, (Clear Creek,) Bear Creek, and at the South Platte. The thicknesses of the beds were esti- mated, and are, therefore, only approximate, but checks of various kinds were used to prevent any gross errors, and when the same series were observed by different persons the results were generally very concord- ant. The beds whose thicknesses were thus obtained have their limiting lines carried through to the vertical line forming the left-hand border of each section, upon which, also, spaces of 100 feet each are indicated, while beds expressing general characters of the series, but not so-ex- actly placed, are carried through only to the line next to the left edge of the section. The several sections are placed with the base of “ No. 1 Cretaceous” upon the same horizontal line. Throughout the series, what first strikes the observer is the marked absence of limestones, and the great predominance of sandstones. Limestones exist, it is true, and, considering their-relative thinness, are very persistent, forming good horizons to refer other’ beds to, but they are wholly subordinate to the arenaceous element. THE TRIAS. General characters.—Resting directly upon the smoothed, though often irregular, surface of the Archean rocks, and forming the lowest member of the exposed stratified formations, is a series of sandstones which varies in thickness from over 1,600 or 2,000 feet to possibly as little as 400 feet, % 96 GEOLOGICAL SURVEY OF THE TERRITORIES. and in which red is so striking and predominant a color that they are commonly known by the name of the “ Red Beds.” Though shaly strata are frequent, and the whole series may be quite soft, yet the general thickness, or massiveness, of the strata forms another prominent and characteristic feature. Most of these sandstones are of a normal red-sandstone type, varying from coarse grits and moderately coarse sandstones, with fine examples of cross-bedding, to quite fine-grained and shaly layers. The latter occasionally may make up a considerable thickness, but though occurring frequently they are generally so intercalated with the heavier beds, that, as said before, a sort of massiveness characterizes the group. Though conglomerates may occur anywhere in the series, they are mostly confined to near the base, where they are often plainly derived from the subjacent rock. It is in these lower parts, indeed, that the beds are so directly made up of the material of older rocks near by that a very little metamorphism has in some instances made it difficult to distinguish small masses of sandstone from the underlying granites. Dark red is the prevalent color, though light-red, yellow, and cream- colored beds are frequent, and may, in places, quite predominate over the red. This is more noticeable near the top, while the conglomerates and beds directly composed of granitoid materials are also generally gray or light in color. Sometimes, also, a peculiar character is shown by sharply defined, often perfectly circular yellow or white spots up to three-quarters of an inch ia diameter scattered upon the deep-red back- ground, as if drops of water in falling on the stone had worked the color from it. This would not necessarily be characteristic of this for- mation, though I did not see it elsewhere. Although the surface of the Archean rocks below is more or less smoothed, it is often irregular, and occasional bosses of granite, Wc., project into the sandstone, as in the accompanying instances, (fig. 2,) observed by Mr. Gardner, near Turkey Creek. Near the Big and Little Thompson’s and Saint Vrain’s Creeks, expo- sures indicate a general shelving off or abutting of the edges of the lower strata against the Archean rocks, or ‘‘overlap,” a point of inter- est to which attention will be called later. Had opportunity offered, this feature would probably have been found all along the base of the mountains. | Local characters.—Toward the north end of the district the shaly character is more marked than elsewhere. At the Little Thompson (see Plate I, section 1) the series has a total thickness of about 750 feet, and is composed of soft granite sandstones and conglomerates be- low, white to red, with coarse soft red sandstones above, followed by two or three hundred feet of shaly sandstone, the whole capped by massive red sandstones about 250 feet thick, but generally breaking into from two to three prominent layers, with thin shaly strata between. Farther north, the lower beds become much shalier than here, while southward the shales grow heavier bedded. In this northern region, the fact that the more massive beds are confined to the upper part of the series, combined with a gentle eastern dip, causes the surface fea- tures to differ somewhat from those farther south. The long, gentle eastern slopes of the massive beds are denuded by erosion, often for several miles ‘to the east of the softer series of rocks which would lie above them, (and yet to be described,) and the lower series, thus occur- ring alone over considerable areas, has a sort of geographical individu- ality given to it. It is this feature, a result of the more massive char- acter of these beds as compared with those above, and this alone, which a 8 EEO a LS ane Ap teen ee nL le f Fig. 1. Diagram showing the relations of the Sedimentary rocks of the plains to the Archean rocks of the mountains. ioe: Congiomernas e Schist Example of irregular Junction between the Archean schists and Jurassic conglomerates and shales, near Turkey Creek.—J. T. Gardner. Fig. 3. To illustrate the shelving off or overlays of the Triassic Sandstone on the Archean, at Dry Creek, between the Big and Little Thompson Creeks. H ar u : , TEA 4 “ ee tee y . fon o 5 H ek ! + Apo 4 a Hy ene ‘ LP ARO tet eee k Sule Boe de as ‘ As Be aM <4 Sc Oh ee EEO ~ Paks > pe f a i: he Hs WOR Sa . i olka 140s aA Pianeta Be balli os wiles Ray ve ¥ aM } MARVINE.] GEOLOGY—ROCKS EAST OF FRONT RANGE—TRIAS. 97 makes it convenient to place the plane of separation between these two lower series just at this horizon, there being no fossils known in the beds to afford any paleontological grounds for a separation at any par- ticular plane. Gentle folding near the north has in places left the red beds forming several ridges, but between the Saint Vrain and Left-Hand Creeks they run into one, and the whole series occurs as a simple upturned ridge dipping away from the mountains at an angle of about 35°, and as a simple fold it continues on southward, only varying much in dip, being in places even turned slightly past the vertical. The general characters, as given at the Little Thompson, also slowly change in approaching Left-Hand Creek. The series thickens slightly ; the top is a thickening band of yellow; the shales have diminished in amount, and the lower part has less conglomerate and yellow, while the general softness is such that the ridges formed are not prominent. These litho- logical features remain much the same to Bowlder City. Here a sudden change in the hardness of the red beds occurs; they become massive nearly throughout, and all the lower 800 feet is of a deep dark red. The hardness is so increased in these lower beds that they rise in a high, ragged ridge reaching over 2,000 feet above the plains, and even con- siderably above the granite buttresses against which they rest. This ridge of hard sandstone reaches south far enough to be cut by both Bear Cation and the South Bowlder, the cafion of the latter being quite profound, while between the two cafions the ridge attains its highest point in Bowlder Peak, one of the stations of the primary triangulation. The latter is, in reality, on a second or inner ridge of sandstone, which has been faulted down from the outer one, as will be shown more in detail later. (See Plate II, section 11.) These cafions give excellent sec- tions of these lower rocks, but this exceptional hardness at this point does not make them typical. In places, however, the origin of the lower sediments is well shown, being often composed of arather coarse aggre- gate of quartz and feldspar, with frequent pebbles of adjacent quartzitic and granite rocks. Lying over this lower 800 feet of red beds, which thus attain an alti- tude higher than any other sedimentary rocks east of the Front range, are about 300 feet of free, clean, gritty, siliceous sandstone, very light yellow in color, inclined to massive in bedding, but cleaving with a fine plane surface. They do not reach very far up on the higher ridge of their harder underlying red companions. Near Coal Creek the red beds have again become softer, and are eroded away till barely exposed. At Ralston Creek they again rise at a low angle to a considerable height, but only to again fall to a valley trough a few miles north of Golden City, where they begin to thin out in a remarkable manner, and at that city scarcely reach a thickness of 400 feet. Their relations, however, are here not wholly clear, as they are quite soft and have been eroded nearly away, the valley trough in which they should outcrop being well sod-covered. They dip from between 40° and 50° near the granites, which form the very abruptly rising western border of the valley, but near their top are thrown somewhat Yeyond the vertical. Section 4, plate I, is scaled from a section given tne by Mr. Berthoud, of Golden City. ~ South of Golden City the red becs again rapidly thicken, and con- tinue to thicken all the way southward to where the South Platte de- bouches from the mountains, the southern limit of the district, where they attain a thickness of over 1,600 feet. Throughout this southern region, though still massive in general character, they are yet quite lod (Gas 98 GEOLOGICAL SURVEY OF THE TERRITORIES. soft, and though often forming a number of minor ridges, the latter no- where rise in prominently continuous hog-backs, while, on the contrary, they may be quite eroded away into a broad valley, with the Archean rocks forming its western side, the beds yet to be described forming their bounding hog-backs in the east. They often rise, however, for consid- erable distances up long gentle slopes of the mountain rocks, which places them in a favorable position to be eroded into the peculiar and grotesque forms which characterize the Garden of the Gods, which, how- ever, isin a very different geological horizon, though somewhat simi- larly cireumstanced. Thecurious groups of worn rocks and monuments thus formed sometimes have their tops worn off horizontally, as if by the surface action of the old retiring sea, while the same sub-aqueous erosion . hasin places smoothly leveled off considerable areas of the upturned rocks, as is best shown a few miles north of the South Platte. (See Plate II, section 17.) THE JURASSIC. General characters.—The series of strata lying next above the red beds form a group of rocks in which the thin-bedded and shaly element de- cidedly predominates. The outcropping edges of these beds have there- fore generally been more eroded away than the harder beds above and below, so that they generally appear in valleys; and being soil covered, they are not usually well exposed. The arenaceous element still predominates, though argillaceous mate- rial is often present to a very large extent, while beds of impure lime- stone occur—one of which appears very persistent—and gypsum is frequent in thin layers, and sometimes occurs in workable quantities and of good quality. As before, red is the prevailing color, though a series of marked variegated colors occur, and weathering frequently produces an ashen-gray tint upon the surface. A brief detail-deseription of sections taken at several points will best convey an idea of the litho- logical characters of the series, proceeding in each case from above down- ward. Section of Jurassic beds near the Béar’s Church, Big Thompson Creek.— Dr. F. V. Hayden, Third Annual Report, 1869, reprint, p. 125. Thickness No. Nature of strata. int feet. Top. 7 | Loose drab-yellow sand, débris of underlying beds, one munesireme 2 feet thick. 6 | Limestone, quite pure, blue, semi-crystalline.........-...----..----- 8 almViariewated clays 2 oe sc tne oOo ee ec eis ae at Sn Sse ea okra iene te 200 4 | Ashen clay, with six-tenths feet of blue cherty limestone, clay part- Se TD CICfS) i eee ea tierce meagre DSSS Na a Ot eR a cee NS 8 5 SHB Ineish lirdestonie i: A ie ent eG ean NS OR Ic ecto Sinema 4 2 | Fine bluish-brown sandstone......--- SUE sees cabrio seu ieee 2 1 Massive reddish-gray, rather find sandstone) (jeunes Guile eee 20 Base. marys.) GHOLOGY——ROCKS EAST OF FRONT RANGE—JURASSIC. 99 Section of Jurassic beds exposed near Saint Vrains Creek.— William H. Holmes. = i Thickness No. Nature of strata. in fone. Top. 14 | Argiliaceous sandy shales, variegated and irregular, crumbling. .---... 20 fomiebiands blue, beautmtul’ limestone (solid= 22 --- 52a. 25 secs o ae cele- os coe 4 12 Argillaceous and sandy shales, same as No. 15..-.........---------- 3 11 | Fine-grained, calcareous quartzite, with seams of crumbling oy psif-_ "STEAD ISR ee gg Rs INT RR 20 UD | 1D iiiCSIOMESeSSeo oss SSSase See SM SsB aS cscs soos See ee Sen eee oO eaeeneree 2 ORES lalliyeeeet se shee cnn See ae) SS Pai es NUE io womaoe sess sine. 5 8 Pac detone.. Seta Seay faeete tamara) apse Maer ae eh ERS 4 7 | Shales, with seams of quartzite. Ee PRC ess PE iene myer e ie teenie als 12 bibs balesandisamdsStOness le sysetrasrectar) eis eee wielecjeeae wehterctee treet we 20 Sip sort) yellow massive sandstone..-- 2.5... ----s-2--+- +22 ssc ee eos 30 AN Sottired massive sandstones: so) sis Sole. Ss esos Soe: 60 Pal Pred Sha liy Sand Stomes! «te sc-siti ncisciome es cek Geach tesco as oe 200 Pa OEE b yall OStONes 2 sie yoe a secre = ec ees Ce eee dos or Spimietvco shally, Sandstones: oi. cesscs cs oct aie seis ese sne seysecie sie sess 300 Base. -—— ARO Haas erick, Shae ves ee ete ee ota tetetei cations oveatitee Seeeren ek cet:) C400=500 Section of Jurassic beds exposed in Bear Cation.— William H. Holines. Thickness No. Nature of strata. ors Top. 11 | Light gray, fine, siliceous shale, alvaoat quiantaite nse si Ga5 ste tye as. 40 10 Sandstones, shaly, variegated, (white, snuff, orange,) containing a shaly limestone..-.-.-.... ae ene, 42 9 | Limestone, hard, gray ; conchoidal fracture, with beds of variegated argillaceous, arenaceous, and calcareous shales..-....------------- 40 Sm RCC OVO LEC erecta eed es Lek ao rey, del eed eNO aS Uefa wae aS Sel iss ae cua 20 7 | Soft massive sandstone, white, with hard siliceous seams ....-.---- -- 50 6 | Limestone, hard, with conchoidal fracture ......-.-.-.-.-.---------- 6 Meoy| Covered (3/2. 22/5 22. UE a Rey eee sey Mies ROR tae ete SS 20 4 | Soft white massive sandstone, with soft greenish coneretions .......- 30 3 | Soft, red, thin-bedded, and shaly sandstones--...--..-.-.-------------- 400 2 Siliceous limestone, T DLORETORD (Shes Ss my ep rs ee ete See i ene ST eS ee 20 1 | Soft, red, thin-bedded, and shaly sandstones . DUETS TAS eae aes ep Meo pp a 200 Bottom. == SO Galle (Alb OU) sys epee eee eye ss paced Behera Sey oats peer ee ote 870 At remaining pcints, though taken in less detail, the sections still show the general features of the series: Section of Jurassic beds exposed near Ralston Creck.— William H. Holmes. No. Nature of strata. Palen ess Top. 6 | Variegated shales, mostly argillaceous, with thin beds of limestones x Ss LG (SGRDLE RFID Leh elise RU DL a ee Lh eg A 270 5 | White sandstones ......- AEA ie Ppa UE BRB TSS se 30 4 | Variegated shales, mostly argillaceous.. Se Pieris ee aca 40 3 | Thin red sandstones and arenaceous shales ..........--2-----+--+--+ 200 MR EUVAITAOSLOMON gt tren criccinee sctisccl-cise ee eaenics The general resemblance between these five divisions and the cor- responding ones in Colorado, but for the great distance separating the two localities, would naturally suggest their direct co-relation and identity. Dr. Hayden has, however, directly traced them, except some easily- passed gaps, across the intervening region, thus establishing their identity. . In his third annual report, 1869, page 121, he says: Quite marked changes occur in the sediments of these divisions in different parts of the West, but by following them continuously, in every direction, from their typical appearance on the Upper Missouri, the changes are so gradual that I have never lost sight of them for a mile, unless concealed by more recent deposits. Again, page 114, in speaking of the Cretaceous in Colorado, he says: At various localities all along the margin of the mountain ranges these divisions of the cretaceous are far less distinctly separated, and vary more or less in their structure and composition, and yet in tracing them carefully and continuously from the Mis- GEOLOGY—EAST OF FRONT RANGE—CRETACEOUS. 105 MARVINE.] souri River they always retain enough of their typical character, so that I have never been at a loss to detect their presence at once, although after leaving the Missouri River we do not find any well-defined lines of separation, either lithologically or pale- ontologically. In Colorado the want of fossils in No.1 has made its position the most uncertain of any of the five; but Dr. Peale’s discovery in these beds of the fragments of leaves in his section near the South Platte seems to fix this horizon with quite a degree of certainty. Professor Lesquereux, in writing to Dr. Peale in relation to these leaves, says that these are fragments of a Proteoides, very near Proteoides acuta, (Heer,) if not a small form of the same. As yet no leaf of this genus has been recognized in our American measures higher than the Dakota group, or No.1. These sandstones, then, probably lie at the base of the Cretaceous. In the so-called Jurassic and Triassic, I believe that not a single fossil has rewarded this summer’s search. In the Upper Missouri, not only does well-defined Jurassic underlie No. 1, so that we might expect to find it beneath No. 1 in Colorado, but Dr. Hayden has traced it also directly to Lake Como, near the Union Pacific Railroad, where it con- tains well-defined Jurassic fossils. In tracing it further south along the base of the mountains the fossils disappear; but in a section exposed on the Box Elder Creek, north of the Big Thompson, Dr. Hayden found some beds which he described (report, 1869, p. 119) as ** undoubtedly the usual Jurassic beds, with all the lithological characters as seen near Lake Como,” and containing a species of ostrea and fragments of Pentacrinus asteriscus, a characteristic Jurassic fossil. These beds are the same that occur near and above the cherty limestone in the sections which Lhave described as Jurassic, and seem to settle the correctness of their assumed age as decisively as possible without the direct finding of fossils in the very region under discussion. THE TRIASSIC BEDS. The correctness of the assumption of this age for the red beds depends only upon their position in relation to other beds of known age, for no- where that I know of have fossils ever been found in these beds. Somewhat north of my district, and between the Cache a la Poudre and Cheyenne, there appears between the red beds and the Archean rocks, outcrops of Carboniferous rocks, so that the red beds here lie be. tween Carboniferous and Jurassic rocks. West of the Middle Park, where all the upper beds retain their characters as east of the mount- ains, the development of the Carboniferous beneath the red beds is far more marked, and consists principally of a second series of red beds of deeper purple hue than those referred to the Triassic. Leaves gathered from the upper measures of these by Dr. Peale are referred by Professor Lesquereux to the Permian. Unless the red beds, then, are referred to the Triassic, there will be an unoccupied gap be- tween the Permian and Jurassic ages; nor would we know to which of these ages the beds in question could be more properly referred. Until fossils are found, therefore, to definitely settle their age, it seems most reasonable to refer them to the Triassic. I have already spoken of the indefiniteness of the line between the Triassic and Jurassic, and have suggested the convenience of placing this arbitrary line above the more massive portions of the red beds, and. above the massive sandstones which usually cap them, and not far be- low- the cherty limestone. 106 GEOLOGICAL SURVEY OF THE TERRITORIES. THE LIGNITIC FORMATION. * We turn now to the consideration of the group of rocks which lies directly superimposed upon the Cretaceous beds, and which, economi- cally considered, is of more importance than any of the preceding formations. This is the formation that contains in its lower portions the lignites of Eastern Colorado. To what epoch of geological time this group of rocks should be referred, whether it should be considered as an upward extension of the preceding cretaceous, or the commence- ment of a more recent epoch, is a matter about which there is still di- versity of opinion. Its fossil flora is very abundant, fifty-six species of vegetable remains having been found at Golden City alone. Yet Pro- fessor Lesquereux, the eminent authority in fossil botany, says that throughout the group not a single leaf has as yet been found identical with a Cretaceous species;+ and, further, that. ‘‘no member of the American lignitic, as far as this formation is known by its vegetable remains, can be referred to the Cretaceous.”{ He concludes, from his extended observations, ‘“‘ that the great lignitic group must be con- sidered as a whole and well-characterized formation, limited at its base by the fucoidal sandstone; at its top by the conglomerate beds. That, independent from the Cretaceous under it, and from the Miocene over it, our lignitic formations represent the American Hocene.” § There seem to be indications near the base of the group, however, of Cretaceous fossils. Lesquereux, himself, calls attention to the fact that Dr. Hayden and Dr. John L. LeConte have each found a badly- preserved Inoceramus low down in the series. Both of these localities, however, have since been carefully but unsuccessfully searched for fos- sils; while the similar occurrences which have thus far from time to time been reported from various localities have, upon investigation, been shown to be the resuit either of inaccurate observation, or that the facts observed were wrongly interpreted, or their bearing over- estimated, or else that they occurred at points where geological com- plications of the rocks made all observation more or less uncertain, as, for instance, at Golden City. Indeed, none of these observations so far recorded can be considered as furnishing evidence in the case, and should be thrown out. Only the occurrence of Cretaceous fossils bear- ing the clearest and most undoubted relations to the adjoining beds, and that at more than one or two exceptional localities, can, under the cir- cumstances, be accepted as defining the age of this great overlying formation. Even if further observations were to show that these oceur- rences were other than exceptional, or, perhaps, accidental, they would not necessarily prove more than that these lower beds only were of Cre- taceous age, or, aS considered by Hayden, beds of transition between the Cretaceous and the Eocene; though, in view of Lesquereux’s idea of the definiteness of the formation as a whole, if the lower beds are proved to be Cretaceous the rest of the series also could hardly, with consistency, be considered otherwise. * So many facts have already been collected from this formation by observers of re- pute that, in any attempt to give as complete an idea as possible of the geology within my specified area, it becomes necessary to draw upon these facts toa very great extent, especially asthe writer’s opportunities for observation in these better-known upper beds were quite limited. The endeavor will be made to make the material obtained from each authority supplement that from the others. The principal sources of information have been the reports of James T. Hodge, Professors Lesquereux, F. V. Hayden, and John L. LeConte, while much practical information has been personally given by Mr. E. L. Berthoud, of Golden City, Colorado. +t Hayden’s Report for 1872, p. 343. t Ibid, p. 419. § Ibid, p. 350. sanye] GEOLOGY—ROCKS EAST OF FRONT RANGE—LIGNITIC. 107 So much for the general character and extent of the testimony thus far presented from the marine life found in or near the base of these beds. Terrestrial vertebrate remains, however, occur under neither so equiv- ocal nor restricted circumstances, but such.as have been found range higher in the formation, and are considered as of decided Cretaceous types, and, judging from them alone, the formation would be considered as Cretaceous.* It must be supposed, then, that either a Cretaceous fauna extended forward into the Eocene period, and existed contemporaneously with an Eocene flora, or else that a flora, wonderfully prophetic of Hocene times, anticipated its age, and flourished in the Cretaceous period to the ex- clusion of all Cretaceous plant-forms. Which of these views is correct is still the undecided point. Though the latter might seem the more probable view, if judged by the rapidity of faunal changes as com- pared with floral changes in the more immediate past, yet not only the great amount, but the remarkable unanimity of the evidence of fossil botany, as interpreted by Lesquereux, would indicate the former. New- berry’s interpretation of the facts from fossil botany, however, again leans toward the latter view. In either case the fact remains that here the physical.and other conditions were such that one of the great king- doms of life, in its progress of development, either lost or gained upon the other, thus destroying relations and associations which existed between them in those regions from which were derived the first ideas of the life boundaries of geological time, causing here apparent anom- alies. Much of the confusion and discrepancy has, in my opinion, arisen from regarding different horizons as one and the same thing. It must be distinctly understood that this group as it exists east of the mount- ains in Colorado is very different from and must not be confounded with the horizon in which much of the Utah and New Mexican lignite occurs, and which belongs undoubtedly to the Lower Cretaceous; and, further, that the extended explorations of Hayden and others would seem to prove almost conclusively that the Colorado lignitic group is the direct southern stratigraphical equivalent of the Fort Union group of the Upper Missouri,t which is considered generally to be no older than the Eocene, while Newberry asserts it to be Miocene.t When all the facts are known they may develop some new ideas as to geological transi- tions. But only the consideration of large areas of country, as Hayden, Les- quereux, Meek, Cope, Leidy, Marsh, and others have already done, will solve the problem. Here we have to do only with the aspects of the forma- tion, whatever may be its age, as it occurs within our district, and for the present we will speak of the formation as the lignitic. § The nature of the rocky fold found along the mountain front, and of the subsequent erosion, has been such that in passing eastward over * See Cope, Trans. Amer. Philos. So. 1869, pp. 40, 98, 243; also Bulletin No. 1 of the U.S. Geol. and Geog. Sury. of the Terr., 1874, p. 10, and Bulletin No. 2, p. 7. + Equivalence founded on similar fossil vertebrates has recently been suggested by Cope. (See Bulletin No. 2 of the U.S. Geol. and Geog. Surv. of the Terr., p. 7.) t Hayden’s annual report, 1870, pp. 95, 96. § The most completeréswmé of the evidence bearing upon the age of the lignite forma- tion has probably been given by Professor Lesquereux in Hayden’s last report, 1872, pp. 339-350. See also Newberry, in Amer. Jour. Science, April, 1874, (III, vol. vii., p. 90,) and Lesquereux, Ibid., June, 1874, (III, vol. vii, No. 42, p.546.) See also Cope, Bulletin No. 2 of U. S. Geol. and Geog, Surv. of the Territories; Meek in Hayden’s report, 1872, p. 461, &c. 108 GEOLOGICAL SURVEY OF THE TERRITORIES. theupturned edges of the strata all the lower formations are found dipping eastward at an angle seldom above 60°, and generally much less, until, upon reaching the Upper Cretaceous and lower lignite beds, they are found—at least all through the middie of the district—to be tipped up nearly vertical, or even pushed over beyond the vertical, so that they appear to dip at a high angle toward the mountains. Immediately there follows an abrupt bend, which at once throws all the remainder of the lignitic series into nearly its natural horizontal po- sition, and thus it stretches eastward as the formation directly underly- ing and forming the plains. All through the plain portion of the dis- trict these nearly horizontal beds have been eroded by the streams into a rolling country, the irregularities of which are really quite considera- ble, the hills frequently rising several hundred feet above the numerous intersectin g streams, and, though generally gently molded in long, rounded slopes, still abrupt and irregular bluffs, formed of the edges of sandstone strata, and of considerable height, occasionally occur. Trees oceur only along the streams—such as the cottonwood and wilow—the hills being clothed in a sort of grassy vegetation of very uniform yellow- green color, so that, standing upon an elevation, all the surrounding hills are thrown against their neighbors with but ‘little sense of relief, and all appears quite level, notwithstanding the decided unevenness of the surface. Along the South Platte River, near and below Denver, the strata dips very gently from either side toward the river, forming a flat synelinal of thevalley. To the east, as the surface gradually rises, pines in scattered groups begin to occupy the country, the precursors of the tract known as the pineries. The rocks comprising the lignitie formation, which directly underlies this country, are principally sandstones and clays. As compared with the older formations, these generally present a much newer or less con- solidated appearance. The sandstones are usually of somber colors; dull reddish-brown and yellow, and rusty gray, perhaps, prevailing. They vary from the conglomerates to quite fine sandstones, and are usually friable, and but seldom compact and firm enough for building purposes. Some few clean, gritty, white siliceous sands occur. The clays which predominate in the formation are of the nature ot fire-elays. They are of various colors, most often perhaps light-gray, generally rather soft, and when very fine and unctuous to the touch are commonly called “‘soapstones.” At Golden City excellent fire-brick, pot- tery, &c., are made from some of the lower clays. The transitions be- tween sands and clays are sometimes gradual, giving zones of mixed material; soapstones becoming gritty, and sands argillaceous. No limestones occur, and argillaceous shale and slate only in very subordi- nate quantities. Fossil leaves, and fragments of wood, &c., are very numerous in some horizons, usually near the coal. They are mostly of deciduous trees, many of which are closely allied to species common in our Southern States and the tropics, the flora of which this ancient vegetation must have somewhat resembled, while no true coal-measure (Carboniferous) plants, such as ferns, &c., have been found. The remains of trunks of trees of enormous size are sometimes met with. The following sections are given as illustrating the general characters of the series: The first, which shows the strata as they occur at Golden City, is from a section made by Mr. E. L. Berthoud, the positions of the outerops being given on Plate II, section 13. It probably shows a greater portion of the full thickness of the lignitic than exposed else- where, for which we have to thank the protective action of the cap of uarvine.) GEOLOGY—ROCKS EAST OF FRONT RANGE—LIGNITIC. 109 hard lava, which has preserved the lower beds from erosion. The sec- tion is from the artesian boring for water at Denver City. The first part is constructed from samples from the well, given me, with descrip- tions, by Mr. Brooks, the engineer superintending the boring, the lower part being furnished. by Mr. Brooks directly, his section being indicated by quotation marks.” The sections illustrating the character of the strata associated with the coal will be given later. Section of the lignitic strata at Golden City, Colorado Territory, from a cross-section made by #. L. Berthoud, civil engineer. | : rs + Thickness “al Nature of strata. aera Doleritic lava, thickness averaging 125 feet: 14 | | Conglomerate and dark sandstone, with layers of buff clay s containing fossil leaves and! plants) -.22-..-- 222-22. -oee- 2h 13 | 8 | Yellow, gray, and rusty sandstones and conglomerates..-... 135 12 | -S | Red, yellow, and gray clays, with streaks of coal, fossil ca- iS) TICS, SEAGes, ANGORASSeRE eee seem | ain eae ee eee eee eee 45 Taba tay Yellow, gray, and white sandstones and conglomerates, with i beds of buff and yellow clay, with fossil leaves..--....---- 13 10 3 Rusty sandstones, with obscure casts of stems and leaves - -- 30 9 | 7% | Conglomerates and clays, probably ..--.....-2....-.-.----. 900 or 1, 000 — Green clays and marls, with septaria : Sa =a Danke Conelomeratemery cam aseiae =) sete Mace el Sige laps vel aye a Mele omleOlavarumaemtarig: csees preter Co Ly acc uae Mccksann cui e 260 6 | S | Fire and potter’s clay, with rusty red sandstone..--...-.--- 150 5 | © | Clays and marls ......-...--.. 52-222 -- 222+ e222 22 eee ee eee 250 4| , | Bog-ore bed, with fossil bones and plants .......-.-......-. 60 Sew |p Sanastonesan dofire-clanse fo Hoyts ne aa sae eae stein cis ere lore : 260 2 | $ | Coal-measures, (five seams or veins of coal) ........-.-.-..- 350 iia wsandstones:and clays, probably c-ss.2ccce ses ees ce eee oe 400 or 500 Total thicknesss of lignitic, from -......---.----..---. 3, 060 to 3, 360 Section of artesian well near Denver City, by Eli Brooks, engineer. Thickness Vi > No. Nature of strata. oueraare 1 | Surface-soil, probably indurated clay pecnuposedy in place by atmo- spheric agencies fe aes eiete ie eta cintrae emyeropejapeie ss chaisie sere Se ale iayetetaictete 20 Cano ht-cuayAclayas| SOUT) SAM Cy =)-tyactarae cel siciee Stacie se sie sisi oe elas siarele oi 55 We PEIN LAC ke SANG patel, atoteyereiere aplete (tole eiomrs chic ois lah meetaolerctmrasciavarciare wisle 20 Ay wlrrecmlariblacks sam! sae jst) ctr: Neto e ceh a eeelais Nattelte aloreter mere aero rte = 5 Dalene hinsiliceousysam de ama claiygryra sella clelatarel viele sleredsrstoe ele! sieeleleistns 16 Geo oral, UMC LM OUSKCLDYga= ole ais lie sien) lem le sieicia ete cise ter eneee ines 16 ee buns lacke samy ss meters alae tele y-/siainta l= cya eialeta ale may eriaiatetava Sciapmieisieiels 68 Sm pleaohb-samcyclanyicersawaere sisi te s mialetejaid am oymietsye are oye wyatelare 35 Weapon Well MOULUAMY Oy Mora deer cs acme ciac sivecccelsn salsa 795 110 GEOLOGICAL SURVEY OF THE TERRITORIES. THE COAL SERIES. At many points scattered through the formation streaks or indications of coal occur. The only points at which their development has reached financial or commercial success, however, seem to be confined to the lower horizons of the series as exposed near the mountains. These horizons would also be found underlying the plains east of their natural outcrops, and could be reached by artesian borings. How deep these borings would have to be, however, to penetrate to the coal horizon be- neath the plains, sufficient examination has not yet been made to deter- mine with any degree of certainty; and even if reached, it is by no means certain, though quite probable, that coal would be found to exist in the same workable quantities as nearer the mountains. CHARACTERS AND APPLICATIONS OF THE LIGNITIC COALS. Chemical characters —The name lignite would imply that these coals were allied to the brown coals of Hurope, a relation indicated by the large percentage of water, usually above 12 per cent., which they contain. At the same time this amount of water is small as compared with that of most foreign lignites, while, instead of having a fibrous or woody structure, they are compact, and generally have a very black color and high shining luster, thus more resembling some bituminous coals. The per- centage of ash for lignites is also low, varying from 2 to 6 per cent., while sulphur seldom reaches 1 per cent., and is often nominally absent. The % volatile products” evolved from coal below a dull red-heat usually vary from 25 to 37 per cent., while the amount of “fixed carbon” gen- erally hes between 45 and 60 per cent., these two components repre- senting approximately the calorific or heat-producing power oi these coals. The above characters would seem to indicate that these coals are superior to those foreign coals from which the term lignite has been de- rived. Since, on the other hand, they differ in some respects from bitu- minous coals, and since their extensive occurrence in the West requires some convenient term which will express to a certain extent their char- acter, I have seen fit to use the term lignite coal or lignitic coal. It has been necessary to thus separate these coals as above into the four principal ingredients—water, ash, volatile products, and fixed carbon—because nearly all the analyses of them that I have been able to find thus separate them. While such proximate analyses, as will be pointed out shortly, do not give sufficient data for estimating closely the actual calorific value of these coals, and would therefore be mis- leading in comparing them with bituminous and other coals, they yet serve, to a certain extent, to compare these lignites among themselves ; indeed, they form the only data for such comparisons at the present time. With this end in view, I have gathered together in the following table all the trustworthy proximate analyses that I have been able to find. They are arranged geographically, commencing in New Mexico and proceeding northward along the eastern base of the mountains through Colorado to the line of the Union Pacific Railroad in Southern Wyoming, thence westward along this line to Utah, then proceeding northward along the Pacific coast, and ending finally with a few localities near our northern boundary. For better comparison, the localities within my dis- trict are printed in small capitals, and are included in the group between the two heavy lines. All the analyses give the percentages of the com- ponents as calculated upon the coal as taken from the mine—that is, including the moisture—except those with the reference “ g” attached, in which the percentages are calculated on the dried coal; that is, after wanvise.| GEOLOGY—ROCKS EAST OF FRONT RANGE—LIGNITIC. 111 the moisture has been expelled. They consequently give too high per- centages of volatile products, fixed carbon, and ash, as compared with the other analyses; and in them, therefore, the percentages of these ingredients should be diminished proportionally to the amount of water present in each. A few words in connection with the heat-producing power of coals. The amount of heat developed in the burning of coal is simply the result or outward expression of the chemical union of the oxygen of the air with those substances in the coal for which it has a chemical attraction or affinity. These are principally the carbon and the hydrogen. The products of the union of oxygen with these simple elements are the com- pound substances carbonic acid and water. The amounts of these pro- duced in combustion represent directly the amount of heat which has been produced as the result of their formation. Having once been formed, chemical action ceases and no further heat arises. If substances are present in the original coal that are now combustible, or already united with oxygen, that is, already burned, they deteriorate the coal accordingly. The ash and moisture present in coals are such substances; they both act as simple impurities, as slate or clay would act, diminish- ing the relative percentages of the combustible ingredients, and hence the heat-producing power of the whole. But the moisture acts further; to convert it into steam requires a considerable amount of the heat pro- duced by the other substances, and which would otherwise be available. The amount of moisture in the same coal may be avery variable quantity; so that in analyses the moisture is often first driven off and its amount determined, and the remaining ingredients calculated as per- centages of the dried coal, as has been observed in those marked “g” in the table. Practically, however, the moisture goes into the furnace with the coal, there to absorb a large amount of heat and diminish the metallurgical value of the coal as a fuel. Analyses which ignore it, therefore, give misleading results. Are there no other ingredients present which would further deterio- rate the coal? In the table above the ‘volatile products” are consid- ered as combustible. Ultimate analyses, however, show them to be composed of carbon, hydrogen, oxygen, and a small quantity of nitro- gen. The latter is simply inert, an impurity, and too small in amount to be of importance. But the oxygen is already united with the re- maining two, and to just this extent they must be consideredas already burned, and so far unavailable as heat-producers. This oxygen is usually considered as being combined with the hydro- gen to form water. From the “ volatile products,” then, there should be taken away as non-calorific the oxygen, and so much of the hydrogen as with it will form water, leaving only the remaining hydrogen and all the carbon as available for producing heat. This ‘“‘ combined water” in the “volatile products” acts just as the uncombined water, or “ moisture,” in diminishing the efficiency of the fuel. To arrive atits amount, ulti- mate analyses only will serve the purpose. ‘To illustrate these points, Mr. Rossiter W. Raymond, United States commissioner of mining sta- tistics, has recently* collected a number of ultimate analyses of lig- nites, (none, however, I am sorry to say, of coals in my district,) some of which I reproduce here, with two additional ones, following him in the lessons he draws from them. I have also added columns 15 and 16, which are explained later: *See Engineering and Mining Journal, May 27, 1873, Silliman’s Journal, Sep- tember, 1873, p. 220, and Report of the Commissioner of Mining Statistics for 1872 : 2 ’ c=) ? TERRITORIES. 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Sos | sos go e ° ® ic) 2 ie 8 . “Bo } Bag ; aa3 ie] Ls} co] "3 Gu F a qskjvuw oe. lS) } ) 4 o 4 Sea 4 4 4 4 s Sd 8 Tet ae 5 a g ¢ ; Be | cB +5 g BE "5 =z Le less! = H cj Be A =) Le of ‘ueSo.1psyy Lariat ‘puowlinvg “AL “yy moif pardopn ‘synoo oyruby wsapsa 14 fo saskjpun you a—g_ LIAVS, FETE b96-9R | OG EL [25s es {moymouIpy 910.4, L8€ (4) TAG || aR IE eee x09019q CTO BT 98 6 OLE0GE | F6GS a |eamnien aaa “-1ep ‘orqerd oF MOTT S6T (Wasi Ete | 5010 ‘Avg soog 6o "Lh PACS) TR Pe ~ 4B9Q Tour ono (9, |) HOG eB Peseorecce® yey ‘wouRy Jeqo 1S 6 696 | 908 | “OAM ‘TOTZBIG TOGIVD QGRCe= {e1ta6Ge ROGET enemas of MA “WOTPLFG TOGID GoLE | 9E70G | 8ES |i seers Joo ‘Aqrg woueD v & G t eca| 2 | fe) See ee 3 ac oF B Pay 4 E Fe ER Ba “AqrTvOOT Gs | 2 4 a5 Bs pS . : o oe “MOqIVD a a nan wanvne,] GEOLOGY—ROCKS EAST OF FRONT RANGE—LIGNITIC. 115 The moisture, or uncombined water-ash and sulphur, in the above table appear in the same manner as in the preceding table. The carbon appears greater in amount because, besides the “fixed carbon,” it in- eludes the carbon before contained in the “ volatile products.” The amount of oxygen included in these volatile products now becomes apparent. If combined with the associated hydrogen to form water, it has thus already rendered one-eighth: of its weight of hydrogen un- available as a heat-producer. The resultant combined water (equal to the oxygen plus one-eighth of its own weight of hydrogen) is given in column 11, and this acts precisely as the moisture does in absorbing heat. Mr. Raymond, in-speaking of the first three columns of calorific powers, which he gives, says: In each of these the amounts are expressed in centigrade heat units, and there- fore indicate directly the pounds of water which could theoretically be raised from zero to the boiling-point by the combustion of one hundred pounds of fuel. The first column is obtained in the tollowing manner: The amount of combined water is found by adding to the oxygen one-eighth its weight in hydrogen; the remaining hydro- gen is multiplied by 34,462, the number of heat-units evolved in the conibustion of hydrogen; and the amount of carbon is in like manner multiplied by 8,080, the calo- Tifie modulus for carbon. The sum of these two products is the number of units gen- erated by the complete combustion of one unit of the fuel, containing the given pro- portions of carbon and available hydrogen. The heat units due the combustion of the sulphur are disregarded, in view of the small amount of sulphur, its low calorific capacity, (about 2,240 units,) and the circumstance that it exists partly in the form of pyrites, the decomposition of which still further diminishes the amount of heat from this source, and partly as sulphuric acid, causing a net loss... The second class of calorific powers is obtained by asimilar calculation on the suppo- sition that the moisture is absent. The third column gives the closest approximation * to the available heat, and is obtained by deducting from the figures in the first the amount of heat-units required to vaporize the moisture and combined water. This is 537 units of heat for each unit of water. In reality, the results in column 14 (calorific power III) should be still further reduced. We have seen that the full amount of hydrogen given in the analysis cannot be realized as a heat-producer, as part of it already exists in the form of water. Is the remaining hydrogen to be regarded as in a con- dition to give out all its great heat energy? It is, in fact, combined with some of the carbon present, probably mostly in the form of marsh- gas, (composed of one part by weight of hydrogen to three of carbon.) and though the two ingredients are both combustible, yet they have to be separated from one another in uniting with oxygen in the process of burning. As the union of elements to form compounds produces heat, so the separation of compounds in their elements absorbs heat, and each unit of marsh-gas thus decomposed absorbs about 1,612 units of heat. In other words, when a unit of marsh-gas is burned it produces but 13,063 units of heat instead of the 14,675 units which would be pro- duced if it were first separated into its components and these then burned, as is implied in the preceding calculation of calorific power III. In estimating the calorific power of the fuel from this last point of view, the amount of hydrogen rendered unavailable as a heat-producer in the form of water remains the same as before. (Columns 6 and 11.) The remaining hydrogen, (column 5,) if its combination with carbou is considered to be in the proportion to form marsh-gas, which is approxi- mately true, must take up three times its weight of carbon (column 4) to form this gas, and the sum (column 4 plus column 5) multiplied by 13,063—its calorific modulus—will give the heat produced in its com- bustion. The remaining carbon only, then, gives out heat in proportion of 8,080 units to one of carbon, and the two products together give the total amount of heat produced, from which, as before, the heat ab- 116 GEOLOGICAL SURVEY OF THE TERRITORIES. sorbed by the vaporization of the water must be subtracted to obtain the actual available heat produced by the combustion of a unit of this coal. Theresults are given in columni15. (Calorific power IV.) They may also be obtained by subtracting from calorific power III 64.5 units of heat for each per cent. of hydrogen present in the analyses over and above that required to form water with the oxygen present. Column 14 gives the relation between the heat-producing power of these coals as compared with that of pure carbon, (8080.) It shows that many of them may be considered as having three-fourths of the calorific power of that substance as represented by perfectly purified charcoal. These numbers, of course, can never be fully real- ized in actual practice, but neither can the full calorific power of pure carbon; they still serve, however, for purposes of comparison, and they show that the inherent or potential capabilities of these coals are far greater than they are usually supposed to be. So much for the quantity of heat that these coals are capable of pro- ducing, if completely and perfectly burned. The temperature produced by this combustion, and which is the chief consideration in the applica- tion of fuel to practical purposes, is another matter. This temperature depends on the rapidity or intensity of the combustion in a given space, and the amount and specific heats of the gases produced by it, and may be as seriously affected by the physical behavior of the fuel as by its chemical composition. That the latter is favorable to the production of high heats is shown above; but before being able to judge of the best mode of application of these coals, their physical characters and behavior must be first examined. PHYSICAL CHARACTERS OF THE LIGNITIC COALS OF THE PLAINS. The lignitic coals of Colorado occur varying from mere streaks of carbonaceous matter to beds 16 feet in thickness. ‘For the most part they are remarkably free from impurities, it being not rare to see a face of 8 or even 10 feet of clean coal of brilliant luster, perfectly sound and . solid in the mine, without a particle of slate or any visible foreign mat- - ter that would injure it. Iron pyrites, however, may generally be de- tected in small flakes and thin disks, but very rarely in sufiicient quan- tity to be injurious. Mineral resin is a common ingredient.” * Their specific gravity is seldom below 1.3, sometimes 1.4. With one or two exceptions, in which the color is a dull black, they all possess a high shining luster, and cleave readily into cubical blocks. When well protected they may remain a long time unchanged, but on exposure to the atmosphere: .they disintegrate very rapidly. ‘This tendency to crumble is the cause of great waste at the mines—all the greater that these tertiary coals can scarcely ever be made to melt and agglutinate into a firm coke. With rare exceptions, when submitted to the coking process they retain their form or crumble into a dry powder.” ‘The coal kindles and burns freely, making a bright fire with a yellow blaze and comparatively little smoke; the odor of this is not so strong or disagreeable as that of the bituminous coals, and somewhat resembles the smell of burning peat. The smoke is not always dark and thick, but is sometimes of a light-gray color. The ashes are remarkably light and bulky.” + * Hodge on the Tertiary coals of the West, (Hayden’s Report for 1870, p. 319.) t Ibid., pp. 319-320. uanvne] GEOLOGY—ROCKS EAST OF FRONT RANGE—LIGNITIC. 117 APPLICATIONS. These coals have been found to serve well for all domestic purposes, either for cooking or warming, and are now largely used both for sta- tionary boilers and locomotives. Their freedom from sulphur, in ren- dering them less injurious in burning out grate-bars, &c., would recom- mend them for these purposes; though with some of these coals a frequent use of the exhaust in increasing the draught is necessary to insure a sufficiently rapid combustion. According to Hodge, the engi- neers find that the more crumbling varieties sift through the grate-bars, requiring closer screens at the top of the smoke-stacks. ‘They endeavor to obtain the coal as freshly mined as possible, on account of its sounder condition. Clinkers sometimes form sufficiently to be troublesome when the coals are obtained from those mines that contain seams of slate.” “These coals are at present also used for the following purposes, for information about which I am indebted to Mr. Berthoud: At the two smelting works at Golden City the best lignitie coal is used in roasting ores, either in close furnaces, or in step-furnaces used in desulphurizing pyritous ores. It is also used at Golden for baking the bricks, &c., there made from the clays of the lignitic series. For gas-making in Colorado the lignitic coals are alone used, while a five-feet bed at Golden City, Caiion City coal, and Trinidad coal are all used in blacksmith- work. é And here we seem to stand on the limits of the usefuiness of these coals. Notwithstanding the high potential calorific power which we have seen that they possess, it remains for some reason unavailable. For all those processes in the arts in which high temperatures are required, the lignitic coals—as compared with anthracite and bitumin- ous coals—have so far proved seriously defective. Indeed, they hardly compare with some of the coals with which they are allied in both physical and chemical features, as, for instance, the ‘“ block-coal” of Indiana, which, though not equaling in calorific power some of these western goals, as Raymond has shown, yet is successfully used in smelting iron. With these coals, however, even for common black- smithing purposes, it has required much experience before they have become to be permanently used for welding, and, while they are used at Golden City for roasting the ores, for smelting them (mostly galena, and siliceous ores of gold, silver, copper, lead, and zinc) a large proportion of Pittsburgh coke is used. One or two experiments in reverberatory furnaces and several trials in blast furnaces have all proved unsuc- cessful. In the former the common fire-box and horizontal grate was used, and in no case was strong artificial draught or pressure employed. What might be accomplished with the many recent appliances in the way of improved grates, fire-boxes, and high pressures remains yet to be seen, but, so far as tried, they have failed as producers of high temperatures. - The cause of all these failures appears to be due simply to the physical behavior of the coal when heated—in giving off their large percentage of moisture they crumble into small pieces. On the furnace-grate this produces a layer not readily penetrated by sufficient air to support a rapid combustion and consequent high temperature, and the frequent stirrings necessary to avoid this difficulty introduces another in the loss of heat incident upon the constant opening of the furnance-doors. In the blast furnace the tendency to crumble is augmented by the super- incumbent weight, so preventing the access of air that the furnace nearly chills without reaching a smelting temperature. They might 118 GEOLOGICAL SURVEY OF THE TERRITORIES. still be made available for this purpose to a small extent by mixing ~ them with charcoal. In Austria somewhat similar coals have been used to the extent of one-eighth or one-fourth of the amount of charcoal used.* The usual process employed to make coals of low calorific power useful, by driving off the moisture, and concentrating, as it were, the combustible material, is the process of coking; but this, as we have already seen, fails with these coals. I believe that no coal so far found in my district has been successfully coked. They either crumble to powder in the process, or make such a friable product that it pulverizes in handling or in the furnace. Further south Trinidad coal makes a fair coke, and Caiion City coal a poorer one. A process has been patented for coking the lignites, but I am in- formed it makes a crumbling, inferior article, unfit for smelting iron, though applicable for light forging. To obviate the great loss arising from the easy crumbling of these coals—and the process would improve their behavior in the furnace as well—Professor Lesquereux has suggested the mixing of the coal slack accumulating at the mines with some agglutinizing material and com- pressing the mixture into coherent_blocks; and for the Western Wy- oming and Utah coals he suggests the use of the bitumen stored in the black shales of the Green River group of rocks near by. Were this to give sufficient coherence to the mass, it is certainly an admirable sugges- tion. Many of the substances used forsuch purposes, as clay, &c., being non-combustible, only subtract from that calorific power in which the lig- nites are originally somewhat defective, while the bitumen would natu- rally assist in their combustion. The enormous accumulations of slack about Eastern and European coal-mines have already led to many ex- periments to render them commercially available. When some of these processes are perfected, their application to western coal-slack may some day form an important industry. But any process which can employ directly or which requires a fuel of friable character is the one best adapted to these coals. Heat-pro- ducing appliances have naturally been designed for the use of coherent fuels, and hence these crumbling lignites have failed when used in their stead. Processes, however, have comparatively recently been intro- duced which attain the very highest metallurgical results, and which are yet assisted by the friability rather than by the compactness of the fuel; and, so far as this character is a factor in the operation, these coals would be admirably fitted for such processes. Such processes may be considered as divided into two classes; namely, those using gaseous fuel, and those using pulverized fuel. The type of the former is the now well-known Siemen’s process, with the regenera- ‘tive furnace. Here the coal, or any carbonaceous matter, is first burned in a small, close furnace, called the “‘ Producer,” in which the object is to produce, not a high temperature, but a combustible gas. For this purpose the fineness of the coal rather aids the process, for the carbonic acid, formed by the first contact of the air with the lower layer of burn- * ing coal on the grate, is then all the more certain, in passing up through the fine mass of incandescent fuel above, to become carbonic oxide, the gas employed in the final operation in the: main furnace. This process has so far probably been more generally successfully used for the pro- duction of the very highest metallurgical temperatures than almost any other; and as not only lignites, but peat, wood, and even sawdust have been successfully used, and all but the latter for the greatest heats, there * Tunner’s Leob., Jahrb., WI, 186. wanvie,]|’ GEOLOGY—ROOCKS EAST OF FRONT RANGE—LIGNITIC. 119 is no doubt but that the lignites of Colorado could be employed in any process embodying this principle. The “ plant,” however, is expensive, and has so far only been economically used, so far as I know, in large iron operations, the ore necessary for which is still wanting in the far West. The principle of producing and using the gases from these coals, however, could still be applied when such high temperatures as require the use of the ‘‘ regenerators ” are not desired. A successful type of a pulverized fuel process is that of Messrs. Whepey & Storer. In strong contrast with the expensive plant of the Siemen’s process, the essential piece of apparatus here is a machine dif- fering but little from afan-blower. The coal, first screened to the size of coarse gravel, is automatically fed into a cylinder varying from 12 to 30 inches in diameter, in which a paddle-wheel revolves at the rate of from 1,500 to 3,000 times per minute. Caught in the rapid revolutions of this paddle—the particles abrading one another in the swift air-cur- rents—the coal is rapidly pulvérized to the finest dust, and, with the accompanying air, is forced in a constant stream through a short pipea few inches in diameter into the previously slightly heated fire-place beneath the boiler, or into the combustion-chamber of the furnace, as is the air from an ordinary fan-blower, every minute particle of coal floated upon and surrounded by the very air which is to burn it, while the supply of either coal-dust or air can be instantly regulated and - varied in amount until so proportioned to one another as to produce the most perfect combustion. Indeed, the conditions for combustion here seem almost perfect, so that, notwithstanding the apparent inadequacy of the means employed, the highest metallurgical heats may be obtained and used on a large scale. It is easily applicable to common boilers, or most heating appliances, and generally requires but slight change in the original apparatus. Aside from the portability and ease of application of the apparatus, important considerations in the West,) the process appears to be so jarticularly adapted to these friable coals, especially in view of the afficulties surrounding their application in other ways, that it seems as iit were in this direction that the lignitic coals of the West could be bst rescued from the metallurgical difficulties which now surround tlem. It is certainly a process which is aided by that very character Oithese coals which renders them unfit for use by the usual methods.* DISTRIBUTION AND DEVELOPMENTS OF THE LIGNITIC COAL. . mm the accompanying map (figure 4) will be found indicated nearly allthe points at which openings have been made on coal deposits within mydistrict, the positions of which with respect to the sections, with but fevexceptions, have been very kindly furnished me by Mr. E. L. Berth- ouc of Golden City. These openings are indicated by prominent black squres, the names of the mines, or their owners, being in most cases attzhed to them; while the outcrop of the coal horizon, as inferred - fror these openings, is given in the strong black line to better empha- sizets position. Oer most of this region this outcrop is hidden from view by the supcincumbent horizontal terrace-beds or detrital material. Along the westrn edge of the maps are the abrupt ends of the massive mountain- * Fr a clear and simple statement of the chemical principles which underlie the com- bustin of fuel, and of the practical considerations affecting the carrying out of these prinoles, and realizing the full value of the fuel, the reader is referred to James Mac- farlay’s Coal Regions of America, New York, D. Appleton & Co., 1873, pp. 626-638. 120 GEOLOGICAL SURVEY OF THE TERRITORIES. spurs of the Archean rocks. Then comes the zone of outcropping edges of the Triassic, Jurassic, and Cretaceous beds, approximately shown by the lining; the first two by oblique lines downward to the right, the last by horizontal lines. To the east, so far as I know, all is of the Lignitic formation. Sections illustrating the relations between these beds at several points (indicated by numbers on the map) are given on Plate II. The basis of this map is compiled from the United States land survey, the town- ships and sections being therefore authoritative. The limits of the counties are shown by the oblique lining downward to the left, while all the railroads at present in operation are also given. It will be seen that, as before stated, the main coal-measures, so far as known and opened, lie chiefly near the mountain-base. From near Bowlder City southward through Golden City to where the South Platte debouches from the mountains is almost a continuous line of openings, among which are the Marshall and Murphy mines, probably as well known as any coal-mines in Colorado. Though at the north the beds dip gently to the east, throughout nearly all the remainder of this line they stand _ nearly vertical, and in places are thrown over beyond the vertical. To _ the north, along the zone of hog-backs, this horizon would probably be. found lying a little above the Cretaceous beds, and it has, I understand, been opened near both of the Thompson Creeks, but so far the demand in this northern region has not required an active search for coal. Instead of to the north, the main openings have been developed to the northeast of Bowlder City, reaching to Platteville near old Fort Saint Vrain. Of these, the Erie and Baker mines are. the most prom- inent. Whether belonging to the same or to a higher horizon in the lignitic group than the former coal-openings, is not yet ascertained with certainty. The best known coal-openings, then, may be considered as arranging | themselves along a line running from Platteville southwestward to near Bowlder City, and then turning southward along the base of the mount-| ains to the South Platte. It is near the middle of this zone that the best and thickest development of the coal seems to occur. aia these openings, excepting a few poor indications of coal at scattere places, the only others that I have heard of lie from fifteen to seventee miles east of Denver City, and near the Box Elder station on th Kansas Pacifie Railroad. In describing what is known of the occurrence of coal at the variow points indicated, I will speak first of this-eastern group, and then, Got mencing at the north, follow southward along the line of openings befo spoken of to the South Platte. The information is gathered mostly fr the reports of Hodge, Hayden, and Lesquereux, supplemented by mu material given me by Mr. Berthoud. It is to be understood that speaking of “‘ mines,” such extensive openings as characterize the e ern coal regions are by no means intended. As yet the demand for ¢al has been but small, and in nearly all cases the mining has been crudéen method and small in extent, though the time is at hand when both improvement and enlargement will be very great. S THH VARIOUS COAL-OPENINGS. East of Denver, in township 4 south, and probably between rares 65 and 66 west, a Shaft has been sunk for some depth in a high bok on the south side of Sand Creek, but is now abandoned. The coal |so CTIONS &c. Nn Zz =— i Pa e Sy Zz. Sees S = ymeuw sss = - © iG Qs $ = Se : SHtk (See Ci = SS Es gts WA eh eee atk Z Mefamurpiiie Arvlacun rocke alovg the Weat Horde Liane el-atlorag of Triastic ww urdarie beta Cretuceons beste [=] (oul herirensotarns kina ™ (oul openings und Mines 2 Liguitic Vormotion upon the Bast Pe bess of the smip ss rompeled From the rats of the C5. Lend. Sherry The paniturts of the wel springs, with recpect tthe Sretion lines. re Mata farnichod by ME EL Barthondof tobe (ity: The paaitiane at snetimne 3 tn 17 of Pate I are indicate new the avet side of he map r { \ are aipereby | . { | { | | | yanvin,] GEOLOGY—ROCKS EAST OF FRONT RANGE—LIGNITIC. 121 outcrops on the bank, and there appears as of a very poor quality. Fossil-leaves are abundant. It was near here that the first discoveries of coal were made in Colo- rado, and the stream at this point is often known as Coal Creek, though ealled Sand Creek farther down. The latter name should be retained, to prevent confusion between this and the better known Coal Creek on the west side of the Platte. About four miles to the north, near Box Elder on the Kansas Pacific road, in range 65 west, township 3 south, section 28, (?) and probably in the same horizon as the last, are two shafts which reach coal, and on which work has been done now and then for some years. It is probably in one of these three shafts that the following section was made by Mr. E. B. Mally, (quoted by Lesquereux in Hayden’s report for 1872, p. 327,) and which serves to give an idea of the strata near here: Section of strata in shaft fourteen miles east of Denver.—E. B. Mally. No. Nature of strata. Thickness. Feet. in. Top. 1 Slaty Chay see US Se ae eR rcs AU culate See Neate Siero as, ahel elcy ee 16 0 3 Yellow clay .....-- a HRP RO Saag cty ink SSN RSE naira cs MOMENI REY A 5 0 4 | Light-blue soapstone . BS Se Naeem ete ers aren cet Noun aictdo emilee 6 0 5 | Brown SOAPSHONG stars ask aa areas ssiae sarsla sa ate Ns wio-oht arn sinjciaise sexatebereie 2 0 6 | Soapstone and clay - Lee aeia ae apo e ia e meia es Poe oN HOE a SAU cote ew ehae 13 0 MM PO LAD SOAPSLONGs+- sats Ho seso erase farce sine co as caelee Sees ev obieee eee sa cares 14 0 SM eDark= bro wal SOapSlOn ess 2 hs sae siatermicue sielerce eos aie Metals ecco E pa (0 ml eblackssl abe wilh-velns Of COale. soesistsiaese secs beset eal ce erssier 5 6 MBC Oda Welland Sinlbby sts cce. seca) oe sctes los see enieniaserc ess onciesas 4 0 IME Onl sme hhOner essa a eisai cryapesah a sear eee crue abe Mme eer due ee 30 Pn black-clayepantin@ =. 22 cijsit2 sissies eel cis i eras ace here carck ete dare 4 Ly Corll eo eee ses otas Ry tyre jou rataya Sete nae hs Oe el a tebe ho @ 14 | Soapstone, blue, brown, Eric li T al ved eaeekay coy a nb a Ye Oa RS NORTE 24% REMMI rimaridrocksesbeks herald ch cel May yay AES TEE Te 1 4 pale SpOLLeOsSang-rock: ASS jcc ovee eee ee a eee 12 0 17 | Very hard sand BOC lara ba de, ety OAC Aan YBa Ser eh ee AE al IG 5 0 em MOOTUSATIC ya Clavres Moco ate epn are cfayeine cian Wutaus Sarat ae Sere IG Bottom. Mo valyseaes Sse 27 See Se a Os eae Ne 142 3 The work was abandoned on account of the poor quality of the coal. Professor Lesquereux thinks that the section indicates the horizon of the bed as being at the top of the great lignitic or fucoidal sandstone under the series of beds of clay and soapstone, as at the Raton Mount- ains. Platteville, range 66 west, township 3 north, sections 17, 18, 19, 20; coal in small veins, now owned by the Saint Vrain Coal Company. McKissack, range 67 west, township 2 north, sections 18, 19; coal in bed or beds some 10 feet thick, now coking, crumbling, and with but little sulphur, as usual. Erie mine, range 68 west, township 1 north, sections 7 and 8, called also the Briggs mine. This opening, which i is one of the larger ones, is on,the west side of a hill facing Coal Creek, the opening being down the gentle slope of the bed east- northeast into "the hill. In 1870 the main adit had been driven 500 feet, with galleries on 122 GEOLOGICAL SURVEY OF THE TERRITORIES. either side, no provision being required on account of water. ‘The coal is glistening black, breaking in rectangular blocks, and oceurs in an upper bed of 84 to 82 feet thick, and a ‘lower one of 3 to 34 feet, sep- arated by a slate parting of 14 feet. The property is owned by the Kansas Pacific Road, and it is “connected by railroad with Hughes, on the Denver Pacific. In 1872 the amount frequently taken out daily was 200 tons. For analysis see Table A, No. 19. In passing up the eastern banks of Coal Creek from the Erie mine, we first pass the Eulner coal-bank, and in about four miles reach the Baker or Douglass coal-bed, range 67 west, township 1 south, sec- tion 6. The Erie coal horizon has meanwhile risen higher and higher on the hills, and at the Baker mine appears some 200 feet above the outcrops then worked. The bed is 44 or 5 feet thick, dipping at a low angle eastward into the hill, and produces a * coal very different in appearance from that of the other mines. A part isa dull jet-black, hard and brittle, break- ing in cuboidal fragments, and streaks of this cannel-like character are seen in the more brilliant varieties that are also found. Iron pyrites in extremely thin disks, and resin also, are noticed in this coal. Two or three other small beds appear in the bank of the creek, and in the slates or shales over them are courses of kidney ore.” (Hodge. See analysis 18, table A.) Davidson's s opening, range 69 west, township 1 south, section 6. This coal, which was found in 1869 near the summit, of the high ground lying about six miles west of the Baker mine, is about 34 “feet thick, and - probably lies far above the main coal-horizon. ; Alan opening, range 70 west, township 1 south, section 12, northeast corner of the northwest corner. Barber opening, range 70 west, township 1 south, section 15, north- east corner of the southeast corner. Marshall mine, range 70 west, township 1 south, section 16, northeast corner of southeast corner, on the east side of the valley of the South Bowlder Creek, about five miles southeast of Bowlder City, and twenty- two or twenty-three miles north-northwest of Denver. This mine was among the earliest worked in Colorado. It was in operation in 1863, has been worked with no material interruption since, and stands among the best mines of the Territory. Eleven seams of coal are said to be recognized here, amounting in all to a thickness of 63 feet in a thickness of beds of 500 or 600 feet. Several of these have been opened and worked, the principal one of which is the lowest in the formation. This bed is nearly horizontal, dipping easterly but 8°, and having an east and west vertical cleavaze. Itis worked to a thickness of from 10 to 12 feet, through the whole of which the coal is remarkably free from slate and other impurities. It contains very little pyrites in thin disks, and some resin in small particles. In the mine the freshly-exposed face pre- sents a beautifully brilliant appearance, and the coal is so found that a cubic block of it, said to weigh over three tons, was taken out for exhi- bition at the fair at Denver. In 1870, according to Hodge, the two par- allel headings or levels by which this bed is worked had penetrated to a distance of 600 feet, being driven in from the north side of the hill, and rising a little up the slope of the bed. From there rooms are worked on either side, but chiefly up the slope. In the other direction, the bed passes under a, meadow where the coal will have to be worked and drained by means of vertical shafts. This bed was then mined for $1.25 per ton, besides cost of props and keeping the track, &c., in good condition. In 1869 the average amount mined per day was 50 tons; in Pavan) GEOLOGY —EOCKS BAST OF FEONT HANGE—LIGNITIC, 123 1872, but 25 tons. The coal is used very generally by blacksmiths, who have overcome the difiiculty they formerly experienced i in not being able to get up a welding-heat with it. A bed 7 feet in thickness, and lying somewhat above the main bed, was formerly mined through a shaft 50 feet deep, while, lying still above, a three-foot bed, capped with fire-clay, was followed for 60 or 70 feet down its gentle eastern slope into the hill. Still higher, a bed known as the Dabney bed is said to be 9 feet thick, and, when worked, furnished coal _of a superior quality, especially for blacksmith s’ use. Several other beds have also been opened to a small extent. I append a section of the neighboring beds made by Dr. Hayden in 1867 and 1869: Section of the lignitic beds at the Marshall mine, Colorado.—Dr. P. Vis Hayden, 1869. 48. Drab clay with iron ore along the top of the ridge. 47, Sandstone. 46. Drab clay and iron ore. 45, Coal, (No. 11,) no development. 44, Drab clay. 43, Sandstone, 15 to 20 feet. 42, Drab clay and iron ore. 41, Coal, (No. 10,) no development. 40. Yellowish-drab clay, 4 feet. 39. Sandstone, 20 feet. 38. Drab clay full of the finest quality of iron ore, 15 feet. 37. Thin layer of sandstone. 36. Coal, (No. 9,) nearly vertical where it has been worked, 12 feet. 35. Arenaceous clay, 2 feet. 34. Drab clay, 3 feet. Bos Sandstone, 5 feet; then a heavy seam of iron ore; then 3 feet of drab clay; then 5 feet sandstone. 32. Coal, (No. 8,) 4 feet. ol. Drab clay. 30. Sandstone, 25 to 40 feet. 29. Drab elay, 6 feet. 28. Coal, (No. 7,) 6 feet. 27, Drab clay, 5 feet. 26.) . ( Sandstene with a seam of clay, 12 to 18 inches, intercalated, t 25 feet. 25. $°° 2 Drab clay, 4 feet. (g = | Coal, (No. 6,) in two seams, 4 feet. 23.) | Drab clay, 3 to 4 feet. , 22. Yellowish, fine-grained sandstone in thin, loose layers, with plants, 5 to 10 feet. 21.) % ( Drab clay, excellent iron-ore. 2, =) Coa (No. 5,) 7 feet. 15 feet. 19.) ( Drab clay. : 18. Sandstone, dip 11°. This sandstone has a reddish tinge, and is less massive than 14. . 17. Drab clay. 16, Coal, (No. 4.) {0 feet, obscure. 15. Drab clay. 14, Sandstone, massive, 60 feet. 13. Drab clay. - Lae GEOLOGICAL SURVEY OF THE TERRITORIRS. ~ 12. Sandstone. . Drab clay. . Coal, (No. 3.) . Drab clay. . Sandstone, 25 feet. . Drab clay. - Coal, (No. 2,) 8 feet. . Drab clay. . Sandstone, about 25 feet. . Drab, fire-clay, 4 feet. . Coal, (No. 1,) 11 to 14 feet. Pai, “In bed No. 22 there are three layers of sandstone, which contain a great variety of impressions of leaves. Below coal-bed No. 6 there is a bed of drab clay, 7 feet thick, with a coal-seam at the outcrop, 3 feet thick; but the coal appears to give out or pass into clay as the bank is entered, so that there are 10 feet of clay above coal-bed No. 6. Much of the iron-oreis full of the impressions of leaves in fragments, stems, grass, &e. The ore is mostly concretionary, but sometimes it is so continuous as to give the idea of a permanent bed. Above coal-bed 5 there is a seam of iron, with oyster-shells, apparently Ostrea subtrigonalis.” Professor Lesquereux estimates, allowing for wastage, &c., that 90,000,000 tons of lignitic coal are probably obtainable from beneath twenty- -five square miles of the Bowlder Valley region. In arriving at this amount, he considers the total thickness of coal obtained over this area as being only 9 feet. For analysis see Table A, Nos. 16, 17. Fullerton bank; range 70 west, township 1 south, section 21. Coal Creek openings: range 70 west, township a south, section 33. These are about three miles south of the Marshall and Fullerton mines, and are separated from them by a plateau twelve to fifteen hundred feet high. They were first opened in 1860, when a drift of 150 feet was driven. The bed opened probably corresponds with the sixth coal-bed, or bed No. 23, of the Marshall-mine section, and was here 7 feet thick. Six other beds have also been found, all dipping eastward at an angle of about 459, but steepening in dips to 68° north of the stream. Underneath the third bed is a layer of excellent fire-clay, 6 or 7 feet thick, having in it nodules of iron-ore containing impressions of leaves of deciduous trees. The bed that was opened had but little clay on either side between it and the usually inclosing sandstones, while above the upper sandstone is another bed of coal and more fire- clay. ‘“Above the coal the clay is very irregular, sometimes thinning out entirely, so that the sandstone comes directly upon it.” All the: ‘beds of coal are so badly crushed to- gether that they are rendered somewhat obscure. From Coal Creek the sandstone ledge above the coal can be easily traced south about four and one-half miles over a broad and highly ele- vated plateau to the Leiden mine; range 70 west, township 2 south, section 28. The bed here appears on the western side of a sandstone ridge, and is bent over slightly beyond the vertical, and appears. dipping at a high angle toward the mountains. The owner in September, 1870, lost his life by entering the mine when the air was foul in consequence of its having been left unworked for some time. Following on still south about a mile, we come to the Murphy mine: range 70 west, township 2 south, section 33,on Ralston Creek; about five miles north of Golden City, and but twelve or thirteen _ miles from Denver, with which it will shortly be directly connected by jt aa : — PNW ROAANMOS wsnvee.) GEOLOGY—ROCKS EAST OF FRONT RANGE—LIGNITIC. 125 railway. This mine ranks with the Marshall, Erie, and Golden mines in importance, and the saine number of seams of coal are claimed to have been found here as at Murshall’s, namely, eleven, but here ail standing nearly vertical. Of these the lowest, or westernmost, was first opened in the south bank of Ralston Creek to a distance of about 30 feet, and found to be 9 feet thick of good coal. The bed next above, however, or about 25 feet to the east, being more conveniently situated and thicker, was worked in preference. A shaft was sunk in this bed on the north side of the stream to a depth of 60 feet, and levels run either way, since when the shaft has been farther sunk to a total depth of 112 feet. Where worked, the course of the vein is south 23° east, magnetic dip - vertical, and thickness varying from 14 to 18 feet, averaging 16 feet, of brilliantly lustrous-cleaving coal, without parting of any kind, and free from slates. For analyses see Nos. 11 to 14 in Table A. In 1870 mining cost $1.50 per ton, coal run out by the miners, who found their own powder, lights, and tools, the owner getting the timber from the mountains; coal was then $4 per ton at the mine. LHighteen thousand tons of coal had been taken out up to 1872. For the greater part of 1873, thirty-two tons per day were extracted, the working capacity being probably one hundred tons per day. On the west side of the bed 4 feet of fire-clay are found suitable for pottery and fire-bricks, and a similar bed 8 to 10 feet thick is found on the east side. Above and below these the usual yellow sandstones occur. Limonite, or bog-iron ore, is found near by to some extent. \ Loveland mine: range70 west, township 3 south, Section 4, near south line; strike north and south; magnetic dip 70° or 80° west; vein 9 feet thick; no parting. Golden City Mines.—In going south from the Loveland bank, the course of the coal formation is irregular, bending in westward behind North Table Mountain, and not showing well upon the surface. Here the Mineral Land Company owns the veins. The first opening is on section 16, township 3 south, range 70 west, where a 2-foot vein has been found. The line of the vertical beds is but poorly indicated by the streaks of coal-smut or blossom. In oneinstance, about two miles north of Clear Creek, these were followed to a depth of 70 feet through fire- clay before they led to solid coal, which was there found to be 10 feet thick. Passing to the south bank of Clear Creek, we come to the Golden City mines proper. These were first discovered in 1561~62, and have been worked continuously since 1865. Several smalland nearly vertical beds quite near together were first found in the steep bank of Clear Creek, about half a mile below where it issues from its mountain cafion. The place was unfavorable for working, and the extension of one of the beds southward was opened on the summit of the ridge about a quarter of a mile from the creek. The bed here was found to be 10 to 14 feet thick, and a shaft 100 feet deep was sunk in it, levels being driven north and south from the bottom, and also at «# depth of 56 feet: The course of the vein is south 53° east, with dip varying from 72° to 65° southwest. The bed proved to be quite irreg- ular in thickness, sometimes pinching to afew inches in thickness, and then winding to 8 or 10 feet. Dr. Hodge considers its average thick- ness as being about 5 feet. He says also that the appearance of the coal itself, whichisof a dull black, without the bright luster common tothe coals from the other mines, has operated unfavorably on its reputation in the Denver market, though no inferiority of quality is indicated by the analyses. (See Table A, analyses 7 to 10.) It is obtained, too, in pieces of very irregular shape, quite unlike the handsome rectangular ‘ 126 GEOLOGICAL SURVEY OF THE TERRITORIES. blocks of the other coals. Like ner however, it is almost entirely free from slate and iron pyrites. Resin occuis in it in scattered particles and bunches more abundantly than in the coals of the other mines. In 1872 the vein was worked from three openings, and up to that time about 8,000 tons of coalhad been mined, theaverage amount being about thirty tons per day. A cross-cut from the bottom of the mine driven 70 feet east, gave the following section, the east or upper end being at the top of the sec- tion: Thickness, No. Nature of strata. 5 in feet. East end, deh eeeetny, 15 | Sandstone - Mee Bs ail Soafla Sa} aati aja) ener cate ge cee 14 | Coal.. oC upeteeete CRA i St oP ate It tale ea geen cee a 13 ODay CECE OANA, Uae TOE FETE 202 | ED TLS SAGE a Ti Oe nnn MOR AC Oalee Mee ae) SSRN OM eae hl er sea ke US LE oa el Ag ee eect a THT CH gt £0299 AEC EIA OSTA Te eae ES a MOEA V IE EMIS Ry tn ib SCL TD) SEROMA OLAS As Shee y SCRE paeabe cooccacosesed GaSlicbe seo sad Clay penta sue Gea CSA Pe PU SS PO NES Be nuchal Cayo eee ree aise site oii iae wlan a cia ere yoteeralnle el aeons eer se aay Samdstome yee Severs eis sa ke oo SiS a a alge Se ee fe Coal... Semis alate Milos Sita Sie ob) Be) 5 wie aieieterayel ore OR palete ee rep co ee res Sandstone... Wage MVS iba Said idle siamo aan et trannies a Sas ater Clay, (west end, lowest, iscolowically).. 121.1) at sae SU ae Ft 0D CO OIG? 2 00 Q & ' ‘ a ' ‘ : a ‘ a o ‘ } o a ‘ ' ‘ : i} . , a i) e e 0 ‘ a a ‘ ' ® e . ‘ 1 ‘ a ' e ‘ t ’ [ee Cl PPNOW NMWOWPWHWNONWAH ox] Miranmico nse dbo tale eee ee Oy oe ae pS ey ia eave The eastern sandstone (No. 15) is probably the extension below of a heavy ledge of sandstone, that forms the crust of the ridge. The clay is all fire-clay, of pretty uniform and excellent quality, very similar in appearance to that of the true coal-measures. It is used for the manu- facture of fire-brick in an extensive manufactory at the base of the hill. Dr. Hayden observed near by the following outcrop of the lower lig- nite beds: East, highest. Rusty yellow sandstone. Fire-clay, with one or two unimportant seams of coal, 10 to 15 feet. Coal, 8 feet. Vire- “clay. Rusty yellow soft sandstone. West, lowest. The clay is used for fire-brick and potter’s ware. In the upper bed of sandstone impressions of leaves ef deciduous trees are found, among them a Platanus. In the southern extension of the Golden City beds we pass several openings, one of which is a shaft 70 feet deep, showing the nearly vertical bed to be 5 to 11, and even 14, feet thick of good coal. Johnson mine: range 70 west, township 4 south, section 3, shows a bed of coal 7 to 9 feet. thick, which is mined from a shaft 90 feet deep. Welch and Loveland mine: range 70 west, township 4 south, section 3, about a quarter of a mile only south of the Johnson bank; course, south 50° east to south 48° east; dip, 71° southwest. Reo ail al oe Of tye —_ le | ———S = — 4 d : = SUP** GF inteRion i area a Barre ar erm nO Plate I GEOLOGICAL SECTIONS ALOXO THK kom juss BASTERN BASE ortux ROCKY MOUNTAINS 2 7 BIG THOMPSON CREEK ro SOUTH PLATTE CANOK i el Te accompany the Report of ———— ——=== ° ARGH. MARYINE woeu vere arisce Seale of Sections 1 to 9), Yamile or 35201 te an each, 10-14 woo... 15-17 loom - . - ~—lirassic No? Cretnecous: MAP. Showing Ue position of the GEOLOGICAL SECTIONS 4 From Nos. 1 to. \Goldea Cily ue Norle ? miles te av inch Cantus 100 fect mpart a 16>. ee Hirndfurd Thill Bical weal a se oo wow a aaa. woman ’ Sp Ae Hipage dt pet eaevegennye at Pee 0 een el as diaivad wane acai tet wanted a plese” Agi 0 ha TP OREE so abun e® ¢ eek Fes Ove wanvee.] GEOLOGY—METAMORPHIC ROCKS OF THE MOUNTAINS. 137 becomes quite probable when one recollects the shelving or overlapping which these strata present, or the similar meaning phenomenon of the appearance of the Carboniferous beds from below the Triassic at the north, as well as the great variations of thickness which occur just to the south. At the same time, some of the facts at hand indicate that a peculiar fault, depending on the nature of the sharp fold, and possibly connected with the lava near by, may have caused the present appear- ance. Enough is not yet known to decide with certainty which of these explanations is the true one, but it is hoped that a few hours’ work dur- ing the coming season may clear up this interesting dynamical problem. A few miles farther south of Golden the formation again widens, though not so rapidly as north of the town, and near Mount Vernon it again presents nearly the same section, (No. 14.) The lower dip of the lower beds growing steeper in passing over them eastward till the coal is reached standing nearly vertical, with the flat beds just beyond, in Green Mountain, gives the usual type of section hereabouts. Nearly the same order is preserved at Bear Creek, section 15. Hast of Creta- ceous No. 1 nearly all is here covered, but a few exposures show the upper Cretaceous very nearly level. This space is followed by an out- erop of the coal horizon, standing nearly vertical, and surrounded by a erayel terrace. Beyond, the Lignitic beds again flatten. South, still the same general features appear. The lower sandstones at first occupy a widening zone, owing not only to a lessening dip, but also to an actual thickening of-the beds. Near Bradford Hill, section 16, they extend quite a distance upon the schists, having a low dip at the west, (15°,) increasing eastward, (to 40°,) and flattening again in No.1 Cretaceous, (30°.) As the coal-measures farther out probably steepen, we have again the common type of fold, a larger fold which seems to carry upon it two minor ones, the upper and western one with a rather large radius, the lower and eastern one more abrupt, often setting the beds beyond the vertical; the larger and main fold, as a whole, being con- cave upward; the minor folds upon it being convex upward. A large area of apparently subaqueous erosion is an interesting feature here. At the South Platte, section 17, the fold seems to be in a, simple curve, the dip of the lower red-beds being nearly 70°; of No. 1, about 50°. The abrupt fold which is so constantly present along the outer part of the main upthrow in all the southern half of the district, is probably ‘due to the crumpling whieh would naturally take place in the upper members of a thick series of rock when folded in a rather sharp curve whose concavity is upward. South from the Platte the mountain fold passes on into the next district. While plication may occur in the plains, it must be to an exceedingly small extent, and wholly subordi- nateto the more profound fold found along the mountain border, the main ~ features of which have just been given. The detail and careful exami- nation of this fold would be rendered quite easy on account of the many cross-cutting streams, and thelessons in dynamical geology to be gathered from it can be of scarcely less interest than the results from the careful study of the historical geology of the region. Leaving the plains, the subject next in order is the geology of the mountains. CHAP TER LEI. THE METAMORPHIC CRYSTALLINE ROCKS OF THE MOUNTAINS. As was dwelt upon at length in the last chapter, the nearly flat sedi- mentary rocks which underlie the plains have an exceedingly well de- 138 GEOLOGICAL SURVEY OF THE TERRITORIES. fined and cogtinuous western border, along which their edges are found folded move or less abruply upward, thus forming the zone of uniclinal ridges or hog-backs which lie at the eastern base of the mountains. Along this well-defined line the occurrence of these rather simply com- posed and structured rocks abruptly ceases, and westward for many ‘miles no sandstones, slates, or shales, or other comparatively little- changed and normal sedimentary rocks are to be found. An entirely different class of rocks take their place. Yirst rising either abruptly or in great massive slopes for one to two thousand feet from beneath the lowest of the Triassic sandstones, they form the first great eastern slope of the main range. This slope is not an unbroken north and south line, for all the streams from the range beyond cut great cation-gashes through it, emerging from which they break across the zone of upturned sedimentary ridges and thence out onto the plains. Moreover, between these greater cafons, the faces of the more continuous slopes are still cut and broken by almost an infinite number of lesser ravines and gulches which drain down the slope to the first longitudinal valley back to the inner sandstone-ridge, and thence north or south to the adjacent greater cross-cutting streams. Rising in this manner to a pretty gen- eral uniform level with higher mountain masses here and there, all cut by the cations into a rugged mountain country, this region extends west for fifteen to thirty miles to the last abrupt rise to the great main crest of the front range, which, in this portion of its course, constitutes the main continental divide, separating the waters of the Pacific from those of the Atlantic, and the topographical characteristics. of which were described in Chapter I. The whole of this portion of the great front range, down its less abrupt western slope to the comparatively smail and lower-lying sedimentary area of the Middle Park, with nearly all of the elevated country lying south of the park and separating it from the South Park, and forming the connecting link between the Frontand Park ranges, and all of the latter bordering the Middle-Park drainage area on the west, together with the southern extremity of the Medicine-Bow range, which penetrates into the park at its northeast corner, and, finally, a few low, small, and isolated areas in the park itself; all this great area, which includes all the grander mountain country, is com- posed of crystalline rocks, schists, gneisses, and granites. Disregarding some comparatively small, and, in this connection, wholly unimportant occurrences of undoubted ancient eruptive rocks, (por- phyries, &e.,) as well as some minor granite areas of uncertain eruptive nature, the series as a whole must be regarded as a great system of an- cient sedimentary rocks which have undergone, in greater part, the most profound metamorphism, the result of which, over large areas, has reached that last term of metamorphism, viz, structureless granite. Though, in the region under consideration, the Triassic red sandstones form the oldest recognized sedimentary rocks which rest upon this un- derlying series of crystalline rocks, and thus indicate that they are only at least of Pre-Triassic age, yet further south and west the Potsdam sandstone covers it in large and well-recognized -areas, thus demon- strating it to be at least of Pre-Silurian or Archean age, a conclusion also rendered almost necessary on the independent ground of the extent, uniformity, and completeness of the metamorphism which has affected the mass. For it is no case of local metamorphism, nor one of supposed depenéence upon adjacent masses of eruptive rock, nor of the acci- dental presence of mineral waters. The metamorphism is regular, or normal, affecting a great system of bedded rocks of unknown thickness and indefinite extent. Throughout the district examined, this character uanyre,] GEOLOGY—METAMORPHIC ROCKS OF THE MOUNTAINS. 139 * of the metamorphism was unmistakable. Disappearing beneath the rocks of the plains it becomes impossible to tell how far the series and its characters may continue in that direction. Where appearing through the sedimentaries of the Middle Park and from beneath them along their western border in the park range, their clearly metamorphic nature is still present. Again covered with the sedimentaries, yet many hun- dreds of miles to the south and west, where the caiions chiseled by the Colorado and its tributaries have penetrated the upper rocks, and on beyond past the limits of the Colorado plateau, in the regions of Ari- zona, Nevada, and Utah that have been stripped of the sedimentaries, rocks similar in character occur, indicating that the substratum of the whole country is what is left of ancient and highly metamorphosed series of rock formations. No special facts bearing on the equivalency of the metamorphic series, as exposed in the front range of Colorado, to any of the divisions of the Archean rocks at the Hast, were observed. Vhe prevalence of siliceous and granitic types recalls the descriptions of Laurentian areas. Bui the presence of granites may only mean extent of metamorphism and not necessarily a greater age. There may, indeed, be therepresentatives of two or more groups of the Archzan present, but a strong impression was received that there was but one great conforma- ble series of rocks, and that its characters might be quite peculiar to the series and region in question. It will be impossible here to go into any detailed lithological study of the series. Though, notwithstanding the extended and rapid character of the exploration, much material was gathered bearing on the subject, yet sufficient time for its elaboration and study has not yet elapsed, and more complete results must be post- poned for a final report. A few general results, however, can be offered. Considering the extent and antiquity, the formation and the probable mutations of its history, its lithological characters, as a whole, seem to be remarkably simple and uniform. From quartzite through siliceous and mica schists te very simple varieties of gneisses and granites, in which the mica is wholly subordinate, and the feldspar mostly a tabular and twined orthoclase, with possibly one or two triclinic feldspars pres- ent, and the list of rocks seems complete. Aside from an apparent tendency at several points to the formation of iron garnets, hardly any other accessory minerals were observed, while the syenitic element and the more basic rocks generally were almost entirely wanting. This does not refer, of course, to the occurrences of many minerals, some contain- ing rare elements, in veins, nor to mere local rock occurrenges, but to the impressions received from the general and extended view of the formation as a whole. The least metamorphosed rocks observed were quartzites, the purest form of which were of clear milk-white or bluish color, excessively hard and compact. Near the lower cations of Coal and Ralston Creeks, where the largest mass observed had been preserved from erosion, they passed into a series of highly siliceous schists, in places very ferruginous, and which may possibly yet be found to contain workable deposits of iron- ore. They were here associated with siliceous mica schists finely, com- pactly, and evenly bedded or banded. Above very irregular schists occurred, contorted and blotched, largely composed of lenticular-like masses of white feldspathic and black or dirty-red micaceous material, intercalated irregularly together, with garnetiferous schists. Gueissic and granitic strata are frequent, while below a great granite mass occurs with but remnants of bedding left, but which are apparently conforma- ble with the seriesabove. Both aboveand traced along the series more 140 GEOLOGICAL SURVEY OF THE TERRITORIES. and more gneissic and granitic beds come in until they wholly predom- inate. At a point farther north, near the Little Thompson, a few exposures of similar quartzites show them to be associated with a highly quartz- iferous series of greenish color, and apparently impregnated with acti- nolite, which occurs in small radiated patches. Bedded directly in the mass are many small granitic and gneissic strata. Longitudinally the beds pass into dark, finely-laminated miea schists, but beyond are lost be- neath the unconformable and comparatively little disturbed . Triassic shales. Beneath them the granitic gneisses occur to an enormous thick- ness, with svhists here and there, all apparently bedded in. conformity. Both these occurrences of quartzite are near the limits of the range, and in the upper portion of the series exposed beneath the newer sedi- mentaries. At two other points only were quartzites observed, one having the radiated actinotite impregnations. Schists inclining to gneisses occur over large areas, but the dominant rocks are granitic eneiss, or even granites, and of these the tendency is decidedly toward a binary granite to which the name of Aplite might apply, a rock with a decided predominance of the quartzose and feldspathic elements, the micaceous ingredient being frequently nearly absent. The latter usually occurs in small black flakes, with the feldspar in greater part orthoclase, in large flat crystals, twined in two thin plates parallel with the flat faces, and. of white or reddish color, the mass being rather loosely tex- tured and inclined to crumbling. Great areas are composed of this sim- ple feldspathic granite, and while it may appear structureless for long ~ distances, yet search seldom failed to find evidences of structure, such as inclosed masses of schist, perhaps several hundreds of feet in extent, passing by imperceptible stages into the inclosing granite. Perhaps patches only a few miles in extent, or a congerie of patches all parallel, but separated by the better defined granite, may only remain to attest former structure. When sufficient mica is present a gneissic structure may indicate bedding, butin the ternary granites, or when the mica isin too small flakes to clearly show a parallelism, the less changed and iso- lated remnants of former structure must be resorted to. In a few in- stances when bedding was not thus indicated by the mica the tabular feldspar crystals were observed all arranged in parallelism with the bed- ding, and in others a marked per cent. of the crystals were so arranged as if the erystalizing forces had been partially controlled by the original structure of the mass, just as in well-defined schist or gneiss the crys- tallizing out of the mica seems to have so been determined. When the almost structureless granite is homogeneous over consider- able areas, the characteristic ‘‘dome” form is developed in the erosion and weathering of the country. The most structureless granite of all was an exceedingly compact and hard porphyritic granite which was observed but in a few small areas. and bore an impress of an eruptive origin. Init the feldspar crystals were not so tabular, while the rock was closely built and not so loosely textured as in the broader masses of the more friable granite with tabular feldspar crystals; yet in one of these masses, apparent transitions from adjacent schists could be ob- served. That the characters noted above are evidences of a structure that once existed throughout the whole mass; that the inclosed schistose patches and areas are neither remnants of foreign schists inelosed in an eruptive granite mass, nor accidental lamination developed by crystalli- zation or motion in a plastic rock, is abundantly proved by the fact that _ whenever, over a continuous area, a great many of the strikes and dips warvie] GEOLOGY—METAMORPHIC ROCKS OF THE MOUNTAINS. 141 of such remnants are carefully noted and platted on the map, they are invariably consistent among themselves in indicating a definite struc- ture of the whole, and accord with the structure that may be indicated by neighboring schists and other masses of undoubted bedded rocks. Thus, suppose a horizon of exceedingly well-bedded quartziferous and mica schists to be under or overlaid by granites which possess in general no distinct structure, and that the foldings have been such that a sharp anticlinal has been formed with its axis dipping steeply to the north. The outcropping edges of the schists would thus appear, forming an angle or curve, with the apex directed northward and widening out to the south, while the beds dipped off outward to the west, north, and east. Now going among the granites above and below, and noting care- fully the directions and dips of all the little evidences of structure found, however insignificant, it will be found that they, too, all accord with the zone of schists, and indicate precisely the same sort of fold. For many miles, often, such a fold may be traced in this manner, perhaps retain- ing the same characters as it is clearly shown to have in the schists, or increasing in sharpness or finally dying out entirely and disappearing. And when it is observed that the zone of schists, when traced longitu- dinally, may also be formed, changed intoa similar granite region, with the same indications and remnants of bedded structure, the proof be- comes conclusive. Indeed, so constantly and without exception did this agreement of isolated observations occur, whenever chance and time threw a sufficient number of observations into a small enough area, that observations at first Jooked upon as doubtful, if not misleading, finally came to be regarded as trustworthy evidences of structure, and the conclusion drawn that, however extreme and profound the metamor- phism may have been, the tendency of its action was to produce a homo- geneous or structureless mass, and never such as to impress on therock definite indication as of a new bedding; and that where indications of structure do occur they simply represent the remnants of bedding that have not been obliterated by the metamorphism, and thus indicate the original structure of the whole mass. Many observations that were at first considered as wholly questionable and provisional, were afterward found to accord with trustworthy data found not far off. Even a much less expected indication of bedding was noticed at many points, though it was by no means accepted as a trustworthy one. When strata of varying degrees of hardness are inclining somewhat, and subjected to erosion, the irregularities of surface formed are almost always steepest on the sides that exhibit the edges of the strata, the slopes with the inclination of the strata being usually much the more gentle, as shown so repeatedly in the hog-backs. Now, over considerable granite or gneissic areas, especially in theregion near Turkey and Last Resort Creeks, the at first apparently structureless granite hills presented their steepest faces to the south, or southeast, or southwest, and in nearly every case the remnants of structure found here and there in them, and which conformed in plan to the plainer schists at the north, bore the normal relation to the form of the hill, 7. e., dipped with their gentler slope, and showed their edges on the steeper ones. It seemed strange that such asimple topographical feature should be preserved in such much changed rocks. Thus it became certain that all the great masses of rock which here compose the archzan areas of the district, the granites inclusive, were metamorphosed in situ, and that the latter, as a whole, must be consid- ered as indigenousin its character, This metamorphism would seem to have been deep-seated. Not only would its nature and extent, judging 142 GEOLOGICAL SURVEY OF THE TERRITORIES. from other regions, indicate it, but the evidence exists to show that an enormous amount of material has actually been removed from the ancient surface to bring to light the rocks as now exposed. The caion-cutting and surface-erosion of the present has only been in progress since the latest uplift—probably in early Tertiary times—and isalmost as nothing in amount, so far as the metamorphics are concerned, compared with erosions in the distant past. Regarding as still correct the evidence from within the district in question, the whole region, except, perhaps, its extreme southwestern portion, stood above the ocean-level at least just previous to the deposition of the Triassic sandstones, and -probably did so all during Paleozic time, and if the erosion then approximated in rapidity to the erosion of the present time, in such a long interval it must have been enormous. ‘That the erosion was by no means gentle is evidenced by the almost universal coarseness of the adjacent derived sediments, the amount of which themselves attest and measure the amount of ma- terial removed from off the adjacent archean areas. The ‘ overlap” and shelving-off of the lower Triassic sandstones all along the east bor- der of the range show a gradual encroachment of the shore-line, a win- ning of the land by the sea, effected by the slow degradation of the land by erosion. How far and rapidly this extended cannot be told, but all of what is now the Middle Park, and probably much farther up on the range, had, by Cretaceous times, succumbed to this degrading and sea- encroaching process. And yet adjacent land must have existed, as the marked coarseness of some of the Lignitic (Hocene?) beds indicate, com- posed, as they are, of granitic débris, and the complemental and actual evidence exists in part in the archéean rocks themselves. Looking at those that are only now exposed to view, some of the lower horizons showing near the center of the range lie many thousands of feet in geo- logical antecedence below the upper exposed portions, and how much the latter may have been below the surface that existed when meta- morphism was in progress, is an unrevealed story, the evidence being hid beneath the ruins of the rocks themselves in the débris that now forms the sedimentary rocks of the plains, but which, as said before, show that much more has been removed than now exposed. ‘Thus the thickness to which the archzean rocks were piled up strata upon strata, before even their own débris was worked over into the more modern rocks, must be recorded by thousands of feet, if not by miles. Thus deeply buried beneath the surface, heat from below must have gradually invaded the mass, and have played an important part in its meta- morphism. That depth, and hence, probably, heat, was a factor, seems indicated by the fact that in a general way the largest and most strue- tureless masses occupy the lowest geological positions, while the less generally metamorphosed regions lie higher up in the exposed series. Some profound plications have occurred in the mass, the strata, generally being highly inclined, and the resistance to this folding, in friction, crush- ing, and motion, must have added much heat to the invading earth-heat following upon the accumulation of the strata. For the metamorphism itself is ancient, the débris of the already metamorphosed rock being frequent in the derived sedimentaries, and I think evidence may be found to show that it probably continued, if it was not most active, during the earlier foldings of the series. The intensity of this heat can hardly be stated. It was not necessarily of that temperature that would be required to melt the granites as they now stand, for the presence of saline waters may have so acted as to have assisted the heat in inducing plasticity or liquidity, to producea state of “ aqueo-igneous fusion” without the actual temperature being very great. How far such action really sanvxn.] GEOLOGY—METAMORPHIC ROCKS OF THE MOUNTAINS. 143 occurs I suppose it difficult to tell, but whatever the conditions, whether more or less heat, assisted more or less by aqueous action, they have apparently been such that plasticity or liquidity has actually been pro- duced in portions of these rocks, and probably to a considerable extent. Such conditions, or a tendency to them, would certainly assist in pro- ducing homogeneous or structureless masses of rock, by allowing freer play of the particles in obeyance to chemical and other molecular forces, and the large granite masses, indicating centers of greater metamorphism, probably also indicate areas of once greater plasticity. While meta- morphism alone has often left sharp lines of demarkation between dif- ferently affected rock, there are also points where movements of the plastic rock seem to have occurred; while, in tracing a line of schist into a granite area, points may occur where the normal granitoid strata regularly belonging to the series may gradually increase in number and thickness, monopolizing the series and producing a normal metamorph- ism; or tongues of granite may invade the schists, as if an active meta- morphism had proceeded outward from the granites, eating, as it were, into the schists, and absorbing first those beds by nature most readily succumbing to the change, and leaving the intercalated masses less changed. Yet the remnants of structure left in the granites still show that no important movement has taken place in the mass, but that the rock remains 7m situ, and is an indigenous granite. But, besides these confusing appearances, lines of the granite sometimes appear as if actu- ally injected or intruded among the schists, sometimes on their bedding, but perhaps across it as eruptive veins. Indeed, there seemed cases where, in approaching the same mass of granite from different points, that at one all the appearances of a truly exotic and eruptive origin might be found—abrupt lines of demarkation and veins; while at another point nearly all the steps of a gradual metamorphism and transition from the schists beyond might be traced, while the remnants of struc- ture through the mass itself would, in greater part, conform to the sur- rounding system of folds, showing it as a whole to be an indigenous mass. Two observers thus approaching such a mass would justly ren- der different verdicts as to its nature, one ascribing to it a wholly erup- tive origin, the other a clearly metamorphic character. A few minor masses of granite did not show well-marked transitions from schists, though in part the ends of the latter gradually, though yet abruptly, merged into the granite, as if absorbed by it, the mass as a whole pre- senting the character of an intrusive mass. There is no evidence what- ever, however, to show that such masses have traveled far, or that they might not have come‘from a short distance only, and have been derived from rocks similar to those in which they are inclosed, or others of the same series, for their likeness may be found at other points as true meta- morphics. Penetrating various portions of the series are granitic, usu- ally mostly feldspathic, veins, many of which probably extend long dis- tances and appear to be of true eruptive character, while other granitic veins, usually of very coarse bluish quartz and white cleavable feld- spar, with sheets and large erystals of white mica, seem to be more naturally referred to infiltration, or to be endogenous in character, like many metalliferous veins, some of each kind showing layers of deposi- tion or structure. Nearly all of the metalliferous deposits, for the pro- fusion and richness of which Colorado is so justly celebrated, occur in veins in this great system of metamorphic rocks, or in débris derived from the same. The more noted of these were studied with care by Dr. F. M. Endlich during the early portion of the season, and his results will be found as a portion of his report as geologist of the southern or San 144 GEOLOGICAL SURVEY OF THE TERRITORIES. Luis division of the survey. A complete knowledge of the general geology of the region as a whole, as well as of these ore-deposits, would probably show connections between the two, and lead, as in other regions, to results valuable to the mining-engineer. To trace such con- nections, and to master the relations of the veins and their contents to the formation as a whole, could not be expected to be accomplished in a single season’s work over an extended area. A number of porphyry dikes, usually of short extent, have penetrated the metamorphic rocks at many points, perhaps most noticeable in the region drained by Left-Hand, Four-Mile, and adjacent creeks. They have considerable variation of composition, but have not yet been made the subject of special examination by the survey. It is on either side of one of these porphyry dikes, along the planes of contact between it and the inclosing granite, that the rare and interesting telluride ores of Gold Hill are mined. Dr. Endlich’s analysis of specimens from this locality has revealed some new mineral species, while specimens of this and neighboring porphyries furnished with notes upon their occurrence td Professor Ben- jamin Silliman, jr., of New Haven, have formed the subject of an exami- pation by him, in the American Journal of Science and Arts for July. The description of these ores, and their mode of occurrence, is given in the chapter on mines in Dr. Endlich’s report. THE STRATIGRAPHY OF THE EAST SLOPE OF THE FRONT RANGE. Three causes combine to render the rapid study of the stratigraphy of the archzan rocks difficult and its results uncertain: First, their struc- ture is not only often complex, but obscure, the evidence of it being at times nearly or wholly obliterated by the metamorphism, and often over large areas very difficult to find; second, this metamorphism renders lithological characters inconstant, so that a stratum that at one point may be characteristic among its neighbors, may, at another, become like them, or all may change so as to retain none oi their geological fea- tures, becoming again like other series, so that lithologival resemblances cannot often be taken as a guide to follow, and may even become mis- leading; third, the erosion producing the present surface features otf the mountain region had the direction of its action determined by movements of the surface which were not closely connected with the extended plications of its rocks; and, moreover, since this erosion has not long been active among these rocks, there appears no well-defined connection between the topography and the structural geology. The ancient erosion gradually wore down the mass to the surface of the sea, and while previously to this it was no doubt directed by the struc- ture, yet the mass was finally leveled off irrespective of structure or relative hardnesses of its beds by the encroaching ocean, which worked over its ruins and laid them down upon the smoothed surface in the form of the Triassic and other beds. The recent great uplift, while it probably added new plications to the accumulated plications of the past in the ancient rocks, was quite simple with respect to their total plica- tion, and left the upper Triassic and other sedimentary beds compara- tively simply structured, they having been affected alone by the later movements. As the mass appeared above the sea and surface erosion once more com- menced, but which now acts upon the recent rocks covering probably in greater part the complex underlying rocks, it was directed off from the line of greater uplift down the long slopes of the rising continent to the retiring marvine.| GEOLOGY——-STRATIGRAPHY OF THE EAST SLOPE. 145 sea. The channels of drainage started were directed solely by the strue- ture and characters of the upper rocks, and when they gradually cut down through these and commenced sinking their cafions into the under- lying complicated rocks, these canons bore no relation whatever to their complications. It is but recently that the upper rocks have been com- pletely removed from the summits of the mountain-spurs, the ancient level of subaqueous erosion being still indicated by the often uniform level of the spurs and hill-tops over considerable areas, and large plateau- like regions which became very marked from certain points of view. Two or three such levels are indicated at a few places, showing not only that the sedimentaries have once extended up over what are now the mountain rocks, but that the uplifting has*been mainly confined along certain partly well-defined lines, the intermediate belts, though uplifted bodily, remaining comparatively level, a type of folding, probably, not uncommon farther west, and which will be referred to again in the fol- lowing chapter. Eroded away, worked farther and farther back, the sedimentaries have receded to the line of hog-backs, and having a structure bearing a partly constant relation to the eroding forces, with persistent lithologi- cal characters, their topographical features indicate their geological structure, and it is through the former that the latter may be most rapidly and easily read, the long ridges nearly always, as shown in Chapter II, conforming to a particular bed or series of beds harder than their neigh- bors, and thus traceable as far as the ridge is visible. Not so the meta- morphics. Penetrating the formerly covering sedementaries, the cafions commenced sinking into the lower and more complicated rocks, with directions impressed upon them by the latest uplift and the overlying rocks, and bearing no constant relation to the structure of the lower ones in which we now find them. It is true that the structure of the lower rocks has begun to affect the courses of the streams, and in places to a considerable extent. Meeting a softer bed a cation will often have its course directed by it, and follow it for some distance, leaving the adjacent harder beds plainly indicated by the ridges, and sometimes the sinuosities of structure are very curiously followed by a stream in all its windings, but it soon breaks away and runs independently of the bed- ding. Many of the smaller ravines have had their positions determined by the structure; but ina broad sense the drainage is from the main mount- ain crest eastward, independent of structure. Thus, while in places geological features may find expression in surface form, yet, as often, there may be no conceivable relation between topography and geology. The subaquevus erosion, in smoothing all to a common level, destroys all former surface expression of geological character, and the present erosion has not yet been in progress sufficiently long to recreate the lost features. With geological structure but feebly featured upon the surface, and with such structure as dces exist, not only complicated, but often lost in metamorphism, it becomes no easy task to trace it out, often requiring close inspection of the rock, and even long search to detect it, while but little definite character can be made out in distant views. On the other hand, the exposures are both numerous and continuous, the many canons affording fine sections of the rocks, and when sufficient time is expended in their examination I conceive that some exceedingly interesting and clear results as to metamorphic action will follow, to say nothing of structural features, and the connection of both with the filling the innu- merable mineral veins which occur in the series with their valuable ores. Notwithstanding the natural difficulties in the way, many observations 10Gs 146 GEOLOGICAL SURVEY OF THE TERRITORIES. of the structure of the mountains, more particularly of the eastern slope of the front or main range, were made during the past season. These, though by no means exhaustive, and, in a sportion of the region, too scattered or imperfect to there define the structure, yet such material as was obtained seems sufficient to indicate certain general features, and a portion of the material from which the inferences regarding the structure are drawn, together with the inferences themselves, are given below. Lithological and metamorphi¢ characters are not here regarded as much as they should be in a complete study, nor as much as they may be after the further study of the notes and specimens yet at hand. The accompanying map (Fig. ‘7) Shows the Archzean area over which the most connected observations were made. It is an area extending north and south across the full width of the district, with the main ‘crest of the front range near its western border. The streams along the northern half of the west border belong to the Middle-Park drainage. The main divide passing out from the western border of the map a little south- west of James Peak, comes in again at Gray and Torrey. On the east are the Lignitic beds of the plains in horizontal lining, with the coal horizon and principal masses of terrace gravels approximately shown, followed by the hog-back zone of more or less upturned and eastward dipping Cretaceous, (dotted,) Jurassic shales, (white,) and Triassic red- beds, (heavier horizontal lines.) To the west extends the mountain zone of Archean rocks to the extreme border of the map. Nearly all‘the observed strikes or curves of the rock are indicated by the short dashes, the direction of which show the trend of the strike, while the little mark on one side shows to which side the rock dips, with numbers sometimes attached showing its amount in degrees, the dips being from the hori- zontal. The shorter line extending across the dash indicates vertical strata, with both sides equal, horizontal bedding, and approximate un- certain strikes and dip, seen either at a distance with a field-glass or too small a remnant of structure to be trustworthy, are indicated by the broken dash. A dash may be the result of a single observation of ob- scure structure in granite, or, more often, may indicate the result of a number of observations, or the whole formation may clearly have the given trend, obviously bending here and there as strikes indicate. Re- garding a number of neighboring observations they serve to show the present structure of the region in which they occur. Drawing dotted lines through a region so that they are parallel to all the strikes near or abreast of which they pass, they may be considered as indicating, approximately, the course the strike would have if the outcrops could have been traced continuously along them. In other words, the dotted lines represent approximately where the continuous outcrop of a horizon, or series of beds, would be if it could be traced. When the structure is clear, or when the. observed strikes are rather thickly scattered, these dotted lines may represent an outcropping hori- zon quite closely, but where the observations are more scattered, the course of -the horizon becomes more conjectural, and the line, instead of remaining on its proper horizon, may gradually pass higher up or lower down through the series, while unobserved faults may throw the beds aside and not be indicated by the lines; yet the latter, though so far incorrect, still serve to connect the obser vation which would otherwise be too disconnected to the eye, -and just so far as the observations go, truly indicate, if approximately, the curves of the outcrops of the folded rocks. An anticlinal, or synclinal, with north and south horizontal axis, would thus have the beds outcropping on either side in north and south ipo US he oer Piste, a i wry 4 tpn Opqat @ i Structural Map oF THE EASTERN SLOPE oF THE Front RANGE Fig. 7. 4 — M7. EVANS Triassic. JTuraaste, Coal » higvartic. Basaltic Terraced sia = —— Hes Quartzite. horizon and Darn. pening (PY yar) AY ts Saquiesssss Approximate outerop of a harizen. == on 1, snd dap, (72. aginky aipin degrees) = -—-—- —> Anticlmal axis Aipping with arraie: ~ Uncwrkain ys 9 a Ryne rnel ” a) ” tin wanvnn] GHOLOGY—STRATIGRAPHY OF THE EAST SLOPE. 147 parallel lines; but if the anticlinal dipped north, the beds would mantle around its northern end in curves, with their convexity or apices directed northward, the beds dipping from it northeast and west, with a northern dipping synclinal would have the curved outcrops pointing south, but dipping northward and inward from allsides. Anticlinals are indicated by dot and dash lines, synclinals by three dot and space lines, the arrow- heads indicating the direction of the inclination of their axes. It is by no means claimed that the map represents with perfect accuracy the geology throughout; it is simply a means of putting together before the eye the observations recorded, and to show, only so far as these indicate, the broader ideas of the structure of the mass. Long study will be required to unravel completely the structure of these rocks, and much that is here inferred may finally have to be modified. The portions represented with least certainty on the map will be mentioned in the fol- lowing brief and hurried description : The portion of the region under consideration whose structure was _ probably most clearly made out is that lying south of South Clear Creek, and having Mount Evans asits great culminating mass. This mountain was approached from the upper branches of Bear Creek, on its northeast side, and for eight miles near the summit no evidence of structure what- ever was obtained, the great massive bosses of rock being often sculptured into dome-like forms, with profound gorges and amphitheaters, all com- posed of normal granites, both coarse and fine, some containing much mica, others with but little, in small, scattered flakes. The different granites were not observed to occur in zones, as if once bedded, but not enough was seen of the mass to say that they did not so occur. As will be seen later, the mass is probably all metamorphic, and a more extended examination of it would probably have developed many evidences of a former structure throughout it. These granites seem to occupy as low a geological position as any rocks observed anywhere in the mount- ains. At the northeast the high ridge rising opposite the mountain from the other side of Bear Creek, and between the latter and Clear Creek, and which culminates in The Chief, is composed of well-bedded schistose rocks, all striking about north west-southeast, and dipping from 25° to 60° to the northeast. The Chief itself, and ridges running from it to the southeast, are composed of very irregular and contorted dirty- red and white-banded schists, often granitiferous, which compose a con- siderable thickness of the formation above. Below, on the southwestern face of The Chief, and extending southeastward, is a well-defined bedded zone of fine, handsome, light-gray granite, with small scattered mica- flakes many hundred feet thick, and in turn underlaid by a still greater thickness of more evenly and finer-banded schists than above the granite, inclined to steel-gray in color, with some irregular schists. The edges of these form the lower southern slopes of the hills, their bases being followed quite closely by the valleys of the main streams, which seem to indicate a well-defined and regular line of demarkation between this plainly bedded series, above on the northeast, and the underlying struc- tureless granites rising in the great slopes of Evans. The impression thus first received is that here are two different and distinct rock forma- tions. The heavier dashed line upon the map here shows the limit of the granites as it follows one of the principal northern forks of Bear River, gradually bending eastward, and indicating, with other strikes observed in the schists above, a flat synclinal, with its axis dipping north- ward. The dotted extension of this horizon southeastward is but ap- proximate, and will be referred to later, while the extension westward is wholly inferred from the observation farther to the northwest, and was mt 148 GEOLOGICAL SURVEY OF THE TERRITORIES. not itself directly traced. Descending from The Chief northward, thus crossing the edges of the steeply upturned schists and ascending through the formation, but at the same time following somewhat along it north- ward, it is found to swing more and more northward, and then—uear a north and south line passing through [daho—to bend directly around to a southwest strike and northwest dip. It is a sharply-folded anticlinal dipping steeply northward. Still following along the strata, they again swing northwest and again southwest, showing a similar abrupt told. Following up Clear Creek from Idaho, a number of such folds oecur, the dip of the irregular schist and gneiss rocks being invariably east, north, or west, but never south until, near the head-waters of that stream, a more constant southwest strike is attained, with northwest dip, as finely shown in the Gray and Torrey Peaks, and north and east of the same. Thus regarded all together, the Evans mass appears as a broad anticli- nal, with its axis dipping northward, and carrying on its face a number of minor crumples, smaller anticlinals and synelinals, like ripples on the greater wave of rock. Naturally these smaller folds render the more general geology very confused. This seems to be particularly the case near Idaho, but many observations showed the same little folds running for considerable distances. The smaller valleys here show some pecu- liar relations between topography and geology, sometimes following the. softer beds in their sinuosities for considerabie distances. The numerous minor anticlinals and synclinals here observed are indicated by their proper symbols. The schists and gneisses appear well exposed in the lower portions of Chicago Creek, but higher up granites begin to pre- vail, very abrupt transitions from one to the other being frequent. Star ting from the eastern base of the Gray and Torrey Peaks, and curv- ing around northward, is a most profound and regular glacier-carved gorge, with sweeping precipitous sides towering up on the east side to the rather even-topped summit of MacLellan Ridge. On the west side, plainly noticeable in Gray and Torrey, the handsome gray and rather evenly banded gneisses dip rather steeply to the west and north, while just opposite, on the east side, an opposite dip occurs, the saddle ‘just east of the two peaks being in a sharp anticlinal axis. Opposite the mountain, and a little sonth, perched midway up the precipitous face of the MacLellan Ridge, its houses held on to the face of rock by chains and rods, and accessible only by the aid of ropes,is the Stevens mine. Here some structureless granite masses confuse the gray gneiss, the mine being in one of them, and faults occur, but it seems to be here that the axis of the anticlinal leaves the valley, for down the latter the general dip is to the northwest. Joining the next fork, the strike still bears east and west, or nurtheast and southwest, dipping north and west, till about midway to Gecrgetown, when a mass of hard, structureless, massive, porphyritic granite is met, in which the Terrible mine is situated. The contact between the schists and granites can be quite readily traced up the steep northern slope of the valley just west of the mine, and is mostly very abrupt. The ends of the westward-dipping schists mostly lie up against the granite, but in places bend down into it, being mueh con- torted, and while the line of contact is often remarkably well defined, the change from one to the other being instantaneous, yet in places the change is less abrupt, the irregular ends of the schist-bands being ap- parently absorbed in the granite mass. Some inclosed patches of schist appeared in the granite, but with no recognizable general arrangement, while below the structureless granite a southeast dip appeared, intimat- ing that the granite occupied an anticlinal axis, probably the ‘northern eontiniation “of the Gray’s Peak anticlinal, as indicated on the map. yarviz.) GEOLOGY—STRATIGRAPHY OF THE EAST SLOPE. 149 Toward Georgetown the schistose-gneisses stand for the most part very nearly vertical, with many faults. At one point near Silver Plume, a small hill on the north side of the valley showed an abrupt synclinal structure, a fault apparently passing directly through the axis. About as far below Georgetown as the Terrible mine is above it, a rock on the west side of the valley, and forming a little promontory at the junction of a side stream, shows the same hard, structureless porphyritic granite as at the Terrible mine, with some abrupt lines of demarkation between it and the adjacent schistose-gneisses, but also presenting some examples of more gradual transition than elsewhere, and deserving of more care- ful study than the time allowed. This porphyritic granite impressed me as being more probably an eruptive mass occupying an anticlinal axis than one metamorphism in situ, though it may not have come from afar, nor from rocks of an origin dissimilar from that of its present com- panions. The dip on the southeast side of this anticlinal must become reversed in rising up against the Evans mass, forming a synclinal be- tween the Gray’s Peak anticlinal and Mount Evans, but as this region was not directly entered, it was not observed, and is not indicated on the map. Returning to the irregular schists of The Chief lying on the Mount Evans granites, and following them eastward, they maintain their char- acters for some distance, but with increasing granite characters, until they appear to cross Bear Creek and merge into a granite country. The hills are less high and sharp than before and rise from a more uniform platean-like surface, with southern sides almost always steep and almost invariably steeper than their massive northern slopes. The rock gen- erally appears to be a reddish granite, with tabular trimmed feldspar — erystals, and small scattered mica flakes; yet remnants of structure are very numerous and can be found in almost every hill. Patches of the dirty-red and white-contorted schists, similar to those of The Chief, occur, apparently indicating approximately the same horizon. Near the bor- der of the range, and approaching the sedimentaries, schists predomin- ate, a line of white quartzite outcrops being observed at one point ex- tending for a little distance. All the rocks still uniformly incline to the north, or else east and west, and none to the south. A most decided unanimity exists among the very numerous recorded strikes and dips observed in the granites, which is confirmed by the adjacent schists, in indicating a series of minor folds with axes dipping northward, some quite abrupt, as shown upon the map. Though concealed by the sedi- mentaries, the last-observed rocks on the extreme border of the archzean rocks seem to indicate that the general strike has swung from southeast to northeast, as if the border was near the principal and northward dip- ping-axis of a great synclinal—the compliment of the main Evans an- ticlinal, with the rocks within it crumpled into minor folds just as the Similar wrinkles exist on the Evans fold. The more southern rocks here are the most metamorphosed, and in tracing them toward Mount Evans evidences of structure become less and less marked until they become so difficult to find in the red and gray granites, that the latter become practically structureless. While the higher mountain-mass beyond may hereafter be found to be partially exotic in character, yet here, upon its southeastern extension, its rocks are certainly clearly metamorphic. It is at points here that an approximate parallelism of the tabular feld- Spar crystals to the bedding was first observed, though it is a character that readily became lost in a wholly fortuitous arrangement of the com- ponents of the granite. Large inclosed schistose masses, with most gradual transitions along their borders into the surrounding granites, to 150 GEOLOGICAL SURVEY OF THE TERRITORIES. the smallest and most isolated of little collections of mica flakes, grad- ually dying out more and more in approaching the central mass, afford opportunity for a most accurate and careful study of the metamorphism of bedded rocks into structureless granites of the most absorbing inter- est. A few uncertain observations in the red granites near the south border of the map may indicate that a southward dipping of the forma- tion begins, and if such is the case, the eastern ridge of Evans may be of an anticlinal structure, the mountain itself thus being at the inter- section of an east-west and north-south fold, just as, topographically, it lies near the intersection of a north-south and an east-west range of mountains. About midway between the lower reaches of Clear Creek and Bear Creek the rather obscurely-exposed granites show gneissic areas, having invariably a high southern dip, or the reverse of the rocks of the chief ridge and to the scutheast of the same, indicating a north- west and southeast synclinal, as skown on the map. This seems to first appear in the cation through which Turkey Creek debouches from the mountains, but here affected by one of the minor north and south folds, and from here on the course of the axis seems indicated at three points, where the rocks were found having an abrupt change of strike, the meaning of which was not at the time understood. What is thus indicated of this axis would show it to dip to the northwest, but the complimentary southeast dip that should occur does not seem to be in- dicated, and its northern end is probably cut off by a fault. The minor folds upon the Mount Evans anticlinal give to the greater fold a squarish form, the northeast corner of which—that at Idaho—being a sharp bend, while the northwest portion seems to be more rounded. These two outer folds are the two principal components of the main fold, and as the latter lies nearest the main axis of the range, it will be mentioned first. From Clear Creek to James Peak no observa- tions were made. At the latter the general strike of the gray-banded gneissic schists forming the main ridge is northeast and north-northeast, and dipping northwest from 25° to 45°. Following them along north- eastward, however, they swing around more and more east to southeast and in places nearly south, with rather low eastern dips, thus indicating an anticlinal, having an axis lying just east of the main topographical crest, and having a northward inclination. South Boulder Creek rises at this point, and for nearly ten miles down its caflon there seems to be an uninterrupted series of schists and gneisses of different varieties, some gray and some garnetiferous, striking more or less northwest- southeast, with northeastern dip of 20° to 502, till the stream enters an apparently structureless granite mass, which will be referred to later. Following northward along the range, the same swing of the strata appears at the Boulder Pass, and again at Arapaho Peak. Through all this distance, from Evans northward, would thus seem to be a great anticlinal, with a northward-dipping axis, and if the series were unin- terrupted, an enormous thickness of rocks must be represented. It is quite possible, however, that unobserved faults occur, the northern side being thrown upward, thus bringing the same series to view more than once. A little north of Arapaho Peak the character changes some- what; some strikes from the northwest instead of from the southwest would seem to show that the axis of the anticlinal was nearly horizon- tal, or rather had a gentile southward dip, as if an east-west synclinal fold had flexed the north-south anticlinal fold. From Arapaho, and from points northwest and southeast of the mountain, many fine views of the great caiion-cut mountain-mass at the north may be had, and the structure generally shown is that of a broad flat anticlinal, with a nearly GEOLOGY—STRATIGRAPHY OF THE EAST SLOPE. 15 MARVINE. ] horizontal axis, the plainer bands of rocks showing as doming over in. great flat curves, with minor flexures here and there, and steepening in dip on either the east or west. Long’s Peak, the grandest mass of all, is mostly of coarse granite, but with several lenticular masses of darker: schistose rock plainly showing in its precipitous glacier-scored sides. East from Long’s generally the country-rock seemed almost wholly of granite, both gray and deep red, coarse, crumbling, and with large tabular feld- spar crystals. But little evidence of structure was noticed, but all that was observed showed eastward-dipping rocks, thus enforcing the gen- eral anticlinal structure of the range. Throughout all this northern portion of the map the dotted outcrop-lines are wholly approximate, and intended simply to indicate probable structure. At Lilly Mountain a more schistose zone, with red granite beds con- taining garnets, was found, which southward gave way to some reddish granites, but seemed to again show itself somewhat plainer between North and Middle Saint Vrain’s Creeks. Hast of Lilly Mountain but random and uncertain observations were made, but what was seen ap- pears to conform to the nearest more certain observations. Close to the border of the range, between the Little and Big Thompson Crecks, and best exposed in the high and rather isolated hill thrown up by the eche- lon folding of this region, rocks of well-defined bedding occur, gray schistose gneiss, &c., changing to hard greenish siliceous rocks, as if impregnated with actinolite, while still farther out, and exposed by faults that push aside the covering sedimentary rocks, are clear white quartz- ites. Between the North and South Saint Vrain’s a few strikes in the mostly structureless granites would seem to indicate a pretty sharp east- west anticlinal dipping east. Tracing these outer beds farther south- ward, a flattening of the formation, south of South Saint Vrain’s, spreads the strikes in a peculiar way, opening out or widening the outcrops of the formations. Still, all the dips are eastward, except one small occur- rence of white quartzite. This appeared as a ridge, only about 100 feet long, rising above the soil of a flattish contoured region, where all other exposures showed the coarse, reddish, crumbling, tabular-crystalled granites, with but occasional evidences of structure, which, however, as just remarked, all indicate a dip in a general easterly direction. The small patch of white quartzite had a well-defined trend of 15° to 25° east of north, and dipped 45° northwest, as if it represented a remnant of an unconformable series resting on the granites. The joints and Seams contained radiated actinolite, and some of the quartzite was tinted green, as if containing the same disseminated in the mass. It thus resembled the green siliceous rocks north of the Little Thompson and elsewhere, which certainly pass into and belong to the schist series. In the neighborhood of Jim Creek the observed strikes appear incon- sistent with one another, and are too few to indicate what the structure really is. For a little way above where Jim Creek joins Left Hand, schists or banded gneisses prevail, as well as on down Left Hand to the sedimentaries, all having a general northeast strike and southeast dip. They are probably the same as those a little north, near South Saint Vrain’s, the two apparently swinging around to join one another along the eastern mountain base, the higher hills at the west being of coarse granites. For some miles up Jim Creek the coarse structureless gran- ites prevail, with porphyry dikes penetrating them here and there. Some débris of true syenite was here seen. This irregularly-banded schist-zone seems to form the high ridge between Jim and Left Hand Creeks, running toward Gold Hill and dipping southeast. From Gold Hill southeast a zone of similar schists and banded gneisses shows here 152 GEOLOGICAL SURVEY OF THE TERRITORIES. and there in Four-Mile Creek as striking south of east and dipping northward. Running from Gold Hill eastward would thus appear to be an eastward dipping synclinal axis, the included surface-rock seeming to be a coarse gray and reddish gneissic granite, some of it containing considerable mica, but much of it, like most of the granites north, hav- ing but little mica, and that in small and scattered flakes. ‘This syneli- nal may be the eastern extremity of the fold that was stated to flex the great north-south anticlinal of the main range near Arapaho Peak, flattening the axis toward the north. The schists running southeast from near Gold Hill seem to continue on westward in a pretty well de- fined zone with some small but obvious north-south folds, as indicated on the map, but with general northern dip. A northwest extension of schists, with south dip, as if the east-west synclinal extended through here westward, does not appear from the few and imperfect observations made in this direction to exist here, indicating that a fault must be re- sorted to to explain the curious outcrop that the map indicates. South of these schists there seems to be shown a pretty sharp line of demarka- tion between them and a coarse granite region across which the North and the Lower Middle Boulder Creeks cut their impressive cafions. Along the cation of the latter a very few imperfect east-west strikes, with steep north dip, seemed indicated, which lower down, near the sandstones, swing southward. South of here, between the Middle and South Boulder Creeks, though no direct strikes were observed, yet the different granites were plainly arranged in zones trending about north and south, but running more southwest in following them southward. Near the mouth of the South Boulder Caton, and resting on these zoned but otherwise structureless granites, the quartzites first appear in force, with a south-southwest strike, and dip of 60° to the southeast. Though mostly quite pure, yet these quartzites may be traced into siliceous schists and are associated with mica schists and gneisses. The above- described structural relations would seem to indicate that these quartz- ites were the stratigraphical equivalent of the Four-Mile schist zone, _ though here by no means so far metamorphosed, and that could the cov- ering sandstones at the east be stripped off, the two might be traced out till they unite and become continuous. The quartzite ridges are well marked, and near the southern end the rocks appeared to show as if folded upon themselves into a sharp synclinal, the east side being thrown even beyond the vertical, and if this is so it may be the north- ern prolongation of the flatter synclinal that appears east of The Chief, as indicated on the map, but this is very uncertain. Attention has already been called to the sharp fold near Idaho, and forming the north- east corner of the greater Evans fold. The region lying directly be- tween Idaho and Central was not passed over, but at Central the rocks indicated a sharp fold similar to that at Idaho, and in view of the per- sistence of the fold south of Idaho it would seem to be the northern ex- tension of the same, as likewise shown on the map. It would then pass on northward and be lost in the structureless granites below the quartzite. These here form the bulky mass of Ralston Butte. The granites here are not red, but gray, the feldspar being mostly a clear, translucent white, and the rock very coarse-grained and exceedingly handsome. Still one or two small isolated gneissic patches were observed. If the stratigraphy is here indicated by the dotted lines this granite area must represent much flattened strata in order to widen out the formation as it appears to do, yet all the observations made near its edges were of steep dipping rocks. The relations, however, all through here are not so clear as it could be wished. In the region near Ralston and Clear. warvme.] GEOLOGY—STRATIGRAPHY OF THE EAST SLOPE. 153 Creeks, and just back of the “hog-backs,” the straight-banded gneissic and siliceous schists and the irregular red and white garnetiferous schists seem folded into a pretty clear case of a southward dipping anticlinal with the west side thrown over past the vertical. Such a structure, however, would be inconsistent with the general structure immediately west, unless we assume the west side of the fold to be in the normal position and the eastern rocks tipped past the vertical. As some of them lie quite flat it hardly seems as if the inversion could have been so great. Notwithstanding the many observations here made the structure does not seem to have been clearly made out, and no attempt is made to indicate it by the dotted approximate horizon lines. The western slopes of the main range, as well as the other areas of archean rocks gener- ally, were not studied even as carefully as the east slope, and but little can be said of them. The western slope of the main range, in its north- ern portion whenever it was observed, appeared to have a general west- ern dip, which was also indicated in all the general views obtained of it. Crossing the great trough-like valley of the Upper Grand River, the high southern portion of the Medicine Bow range, where visited, was of a very sharp anticlinal character, the rocks appearing folded quite flatly upon themselves. It is quite possible that the fold is recent and that the sedimentary once mantled over it, filled the trough of the Grand, and ran far up on the main range. When the broad rolling ridge of the Park range was touched, at the extreme northwest corner of the Middle Park, it presented only a massive granite of the very coarsest description, with great crystals of feldspar, and no observed structure whatever. Many miles south, where the range rises on the great Blue River group of mountains, schists and gneisses predominate. These all seemed to have a pretty uniform trend, following pretty closely the remarkably Sharp spurs running out northeastward from the main ridge and dipping southeastward. In Ute Peak the trend runs nearly east and west with a nearly vertical dip. In Mount Byers, the northwest spur from the Berthoud Pass group of mountains, the strike was mostly with the spur. The great east-west ridge connecting the Evans group with the Park range, and forming the divide between the Middle and South Parks, was not examined. It is unfortunate that more definite and positive results could not have been arrived at, but when the extent of the area traversed, and the short time employed, together with the fact that other rocks demanded attention, and the peculiar difficulties in the way of this special study, are all taken into consideration, the outcome of the season’s work can- not be regarded as so very small. The fact that the great front range is practically composed, throughout this region at least, of metamorphic rocks, and that these rocks possess a definite and accessible structure, is certainly shown, and while errors may be found in minor points, yet it is believed that the more general structure of the range as shown in the map will be ultimately found to be substantially correct. Some of the topographical features of these rocks are dwelt upon in the early part of the following chapter, when speaking’ of the upper valley of Grand River, and later when describing the Blue River Mountains. It is hoped that a more complete digest of the notes, with study of the Specimens, aided perhaps by chemistry and the microscope, may not only add interesting results to the lithological and metamorphic ques- tions involved, but assistin perfecting the knowledge of the stratigraphi- - eal structure of the range as presented above. ’ 154 .GEOLOGICAL SURVEY OF THE TERRITORIES. COREA EER Ve THE MIDDLE PARK. In Chapter I was given a brief description of the principal topo- graphical characters of that region, the drainage system of which, as a whole, may be considered as composing the Middle Park. The general symmetry of this drainage, with Grand River as an axis, its radiating tributaries, as well as the remarkable isolated character or unity of the system, all of its waters finding their exit through the single outlet— cafion of the Grand—were there noticed, and attention called to the fact that, notwithstanding the great basin-like character of this area, as indicated by these features, yet this character is in great part lost by the prominence of many of the ridges separating its secondary drainages, and the general diversity of much of its surface, wherein it presents a striking contrast with the far-better defined basin-like character of the North and South Parks on either hand. The fact that this isolated and independent system is the easternmost region in the United States, in which Pacific waters take their rise, was also referred to, while it was suggested that, as a geological basin, the northern side is wanting. The general course of the streams forming the system, as well as the more Salient features of their valleys and separating ridges, were also briefly sketched out. The distribution and structure of the rocks forming this region will now demand our attention. (See map at front of chapter, Fig. 8.) All the eastern, southern, and western rim of this isolated drainage basin, as well as the massive mountain areas bordering much of the same, chiefly on the east and south, are composed of apparently the same system of metamorphic crystalline schists and granites that are found on the east slope of the range, excepting always certain smaller areas of Paleozoic sedimentary rocks, which occur near the sources of the Blue River, and which are quite separated from the younger sedi- mentary rocks to follow, and will not be further considered in this report. All the northern and middle portions of the park, which include all the lower and more truly park-like portions, are composed, excepting a few areas of Archean rocks along the Grand, of younger sedimentary rocks, which are not, as arule, greatly disturbed. THE CRETACEOUS FORMATION OF THE MIDDLE PARK. Apparently the oldest of this series, resting, where found, directly upon the crystalline rocks, is the Cretaceous. This formation seems to vary from about 3,500 to about 4,500 feet in thickness, and is divided much like the Cretaceous upon the east side of the range, with some very strong lithological resemblances existing between some of the divis- ions. . At the base is a series of sandstones, some of which are red, and both massive and shaly, but the most characteristic feature of the group is the presence of hard, whitish or white, highly siliceous sandstones, often conglomerates, which, at times, form such compact quartzites that in hard specimens the rock can hardly be distinguished from some ar- chean quartzites. Being so hard, erosion has generally molded these sandstones into prominent exposures, leaving the softer beds in less no- ticeable positions, while their marked persistent lithological characters 7 1A9190.1050, i 7. 0 neue : eC. 4 ; ae 40 Baorede agit < ouRwOne 2 7 AR ATA ad y enITDsE | if SL AAIVAAM HORA i: 2 Moiese Hath AIG “2% BRL. Shs Pt-5. 4 Fy n® ‘‘s an AY Ph I a ene —" ‘ f en To 4“ Fig. 8. GEOLOGICAL MAP OF THE ele Aap fon igll TERS oe oes | MIDDLE - PARK — = 4 \ == oy — = A> ARAPAHOE-PK.> 2 MY : -fo® ag = , \ u SHOWING THE POSITIONS OF THE SECTIONS ON PLATE Iil. To accompany the Report of ARCH. R. MARVINE MIDDLE PARK DIVISION . 1873. Busaltic lara ZR. Moraines Lake Beds and Alfurium Lignitie DeheriticBrevea MM OPE ACOOUS | Airhe@an CES aoe a " | . ‘ * re ’ F ; i x i ‘ - P ‘ f \ * eo Aa ¥ co it ; Py o) . ‘ a ) ; ie : ‘ i iy , Ke] N aS N Busatltit May or Lake Beds oe VS — YAO UPEMUTIL AY 40 TE. and All CTU. OPETLCCOU pmiles Seale rs St & rh AP survne] . GEOLOGY—CRETACEOUS OF MIDDLE PARK, 155 render them easily recognizable. These sandstones, therefore, naturally occur near to, and dipping at angles of from 10° to 50° away from, the ridges of archzan rocks surrounding the Cretaceous areas. This group appears to vary from about 350 or 400 feet, near the Hot Springs, to, per- haps, 1,200 feet, near the head-waters of the Muddy. At the summit of the formation there is also a series of sandstones. Here, however, the predominent colors are rusty-brown or yellow, and while shaly sandstones occur, the more massive beds are soft and friable in nature, and often concretionary. From only about 700 feet at the east, these may become 1,600 feet thick farther west. Between these two series of sandstones, and all through the middle of the formation, embracing an average thickness of, perhaps, 200 feet, dark argillaceous slaty shales prevail. These naturally contain arenaceous beds here and ‘there, which sometimes become quite numerous, more especially toward the top. No well-defined division of these middle beds was observed. In the northwest portion of the park, however, and about one-quarter or one-fifth of the way up from the base of the shales, is a horizon at which calcareous beds tend to occur. ‘These usually appear as thin limestones, consisting sometimes of two or three more prominent beds, with several minor ones, the thickest reaching, perhaps, not much more than 15 feet. Though inclined to tabular, or irregularly thin-bed- ded, the limestone is sufficiently harder than the adjacent shales to ap- pear, when thick enough, as a hog-back-like ridge above the surface. It is brownish compact saccharoidal, and often almost wholly made up of Cretaceous fossils, the principal one of which resembles closely Ino- ceramus acutirostris, a fossil of the Cretaceous No. 2, of the Nebraska section of Meek and Hayden. ‘These limestones bear constantly a characteristic odor of petroleum. The usual Cretaceous fossils are found here and there through the middle shales, and appear quite numerous in the upper friable sand- stones. At one point in the latter, fossils, probably the Inoceramus bar- abint (Morton) of the Cretaceous No. 5 of Nebraska, were found. There thus appears to be avery striking resemblance between the general arrangement of these groups and the five divisions of the Cre- taceous, while the lower and upper sandstones present lithological char- acters remarkably similar to those of No. 1 and No. 5, respectively, of Hayden’s divisions of the Cretaceous as present east of the mountains. The true equivalent of No. 3 may not have been recognized, and though the Inoceramus acutirostris (M. and H.) of the thin limestones which occur in the lower middle slates may indicate it as belonging to No. 2, yet this horizon of calcareous sediment would seem, on other grounds, to be the real representative of No. 3, and is so given on sections 2 and 3, Plate III. A complete examination of the fossils is needed to estab- lish the true correlations. All these softer portions of the formation occupy the valleys, and are mostly covered with subsequent beds, ren- dering their characters not readily studied, and not always clear. The representatives of Nos. 2 and 4 are much more strikingly argillaceous than along the east base of the range, and may be undistinguishable from one another unless the beds assumed as No. 3 occur distinctly enough to separate them. Though no fossils were observed in the lower siliceous sandstone, its relations to the beds above, as well as its lithological character, show it to be identical with the Cretaceous No. 1, east of the range. Near the entrance of the park, and on the Upper Muddy River, there was a much greater thickness of the redder and softer beds lying between the more characteristic quartzites of No.1 and the archean rocks below, Y 156 GEOLOGICAL SURVEY OF THE TERRITORIES. than in the remaining portions of the park. These may represent small portions of the Jurassic caught between the Cretaceous and the under- lying archzan; and if so, the Jurassic should be represented as occur- ring in the park. On the other hand, however, they do not strongly resemble the variegated arenaceous shales of the Upper Jurassic, which, both east of the range and west of the park, occur below the Lower Cretaceous, while they do contain thick beds of siliceous sandstone very like those characterizing the undoubted No. 1, just above; and, moreover, in beds laid down upon a newly-prepared sea-floor of far older and non-conformable rocks, as these were, unevennesses of the under- lying surface and corresponding abrupt changes of thickness of the newer beds are to be expected. I have, therefore, in view of these con- siderations, and in the absence of fossils, regarded these beds as form- ing a portion of the Cretaceous No.1. The transition between No. 1 and the slates above is abrupt, while the shales of No. 4 and sandstones characterizing No. 5 appear to commingle, giving no marked line of sep- aration between them. As was first distinctly pointed out by New- berry* east of the range, so here in the middle park, the general aspect of the formation as a whole is that of a “circle of. deposition,” an en- croaching shore-line deposit of sandstones attending slow submergence, followed by a deeper water sediment forming slates and shales, but not ‘reaching sufficient depth or attaining the proper conditions to develop extended limestone deposits; in turn followed by a shallowing sea, with more arenaceous accumulations. The latter shallowing probably accom- panied, perhaps as an effect of the same cause, the formation of a gen- tle anticlinal fold, found along the lower portion of the Grand River, and which occurred shortly after the deposition of the No. 5 sandstones, and before the laying down of the next great sedimentary deposit, as will be seen later. A thin seam of coal occurs in the lower mid-cretaceous slates, a few hundred feet above the quartzitic sandstones of No. 1, at the Hot Springs, indicating that coal-forming conditions existed far below the usual lignite horizon just east of the range. The latter, as shown later, seems to be also found in the park, but very poorly indicated. DOLERITIC BRECCIA. Above the Cretaceous No. 5 the next youngest rock is a local occur- rence of volcanic doleritic material, consisting partially of subaqueous- arranged material—dolerite, tuff, and breccia—and partially as accom- panying lava-flows; in all, reaching a maximum thickness of 800 or 900 feet. THE LIGNITIC FORMATION OF THE PARK. Resting upon the latter when it occurs, but elsewhere upon Creta- ceous No. 5, and apparently conformable with the latter, except at one point where there is a decided unconformability, is a series of beds which reach a thickness of about 5,500 feet. Not being capped with any beds following them in direct geological sequence, it is impossible to tell how much thicker they may originally have been, erosion having already removed an unknown amount of them. They are composed in part of sandy shales, in places more or less argillaceous and quite soft, spaced rather regularly with more prominent and characteristic hori- *American Assoc. meeting, Newport, R.I., 1860; also, later, Proc. Am. Assoc., Aug., 1873, p. 185, &e. a GEOLOGY—GLACIAL OF MIDDLE PARK. 157 zons of coarse sandstones, which are often inclined to grits and fine conglomerates. The texture of the latter is usually open and not firmly compacted, while the material of which they are composed is character- istically the débris of the archzean rocks of the mountains, granitic dé- bris prevailing. While some of the finer-grained massive beds are som- ber brown in color, the usual colors are light gray or whitish. Escarp- ments of the harder gravels, reaching 30 feet in height, separated by shaly slopes of 5 to 10 feet, cften make up the hill-sides, while every few hundred feet in altitude a predominance of the more massive gravels has caused the erosion to carve the whole formation into a series of high terrace-like steps, in places well defined, but in others indicated only by changes of steepness in the long, wavy, graceful slopes of the hills. It generally forms a high broken-terraced region. Impressions of decid- uous leaves are quite numerous at favorable localities and small isolated patches, and one or two thin seams of carbonaceous material were also observed. No other fossils were observed in these beds. It has been strongly affected by the last great folding accompanying the formation of the Rocky Mountains, portions of it being abruptly upturned, to- gether with the underlying sedimentary rocks. In position and char- acter, therefore, this group of beds appears to be the equivalent of the lignitic ‘group east of the mountains. Here, as there, in view of the as yet disputed age of these beds, whether Cretaceous or Eocene-Ter- tiary, and to avoid possible error, the non-commital name of lignitic formation will be at present retained. These beds are intersected to their highest points by dikes of handsome light-gray, porphyritic trachite. LAKE BEDS OF THE MIDDLE PARK. After the lignitic there is a geological break, the beds next following being of far more recent age. These occur nowhere at the higher eleva- tions, but occupy all the lower basins. In these, and following the streams, they usually form broad, low terraces, often much cut by the lat- eral streams into isolated pieces or long even-topped tonguesrunning out from the valley sides. Near the borders of these areas these beds oxten plainly show that their material was derived from the adjacent rock, often being of coarse. granitic or schistose débris, or of the lignitic sand- stones worked over; more frequently they are of finer sands and of characteristic marls of exceedingly white color. They are usually found resting on the archean rocks, as along the Lower Grand, or on the softer shales of the Cretaceous, which, in former times, as now, afforded the weakest lines for erosion to work most successfully at, and which, there- fore, occupy nearly all of the lower areas. Along such lines, then, the streams cutting through these terraced beds, constantly expose beneath them the more or less upturned edges of the Middle Cretaceous beds. They show a thickness of probably not over 300 feet at any one point, though their vertical range seems to reach to or above a thousand feet. A few dips of ten, possibly of fifteen, degrees, were observed in them in the eastern portion of the park. Unfortunately no fossils were found in these beds, leaving a satisfactory determination of their age impos- sible, though they are undoubtedly very late, or, perhaps. Post-tertiary. They may, following Dr. Hayden, be very appropriately called lake-beds. GLACIAL. In the Upper Grand, and at the base of the Blue River Mountains, are extensive glacial moraines. Though no good exposure was observed 158 GEOLOGICAL SURVEY OF THE TERRITORIES. proving the fact conclusively, yet the manner of their occurrence is such as to indicate that they were, in part, contemporaneous with the lake beds, the upper terraces of the latter apparently covering and mantling around their ends. Alluvial material occurs here and there adjacent to the streams, and may in places have been taken for lake beds, being probably the same material worked over. Indeed, the alluvium is in places the later pro- duct of the same or similar forces which produced the lake beds. With the alluvium should be classed the meadows inclosed by the gla- cial material. Basaltie lava covers wide areas, forming some of the highest points, where it usually caps, as a protective covering, the lignitic sandstones, though it has also run down into the lower regions, covering large areas of the lake beds. Having spoken thus generally of the various rocks composing the Middle Park, their more special characters and distribution will now receive attention, taking up in succession the various areas which com- pose the park. ; THH VALLEY OF THE UPPER GRAND. The North Fork of the Grand River occupies a profound valley lying between the southern end of the Medicine-Bow range, upon the west, and the Long’s Peak group, of the main range, upon the east. Looking up this great valley from the south, the walls of rock seem to rise in great, abrupt, but rather even, massive slopes to a pretty general mountain level on either hand, the bottom of all the lower portion of the valley being quite flat, and averaging about two miles in width. Within the valley, however, the numerous great gorges coming down from either side, chiefly from the east, so break up the apparent regularity of the sides as seen foreshortened from the south, that the impression is of a maze of rugged mountain spurs and caiions. Those from the west are of lesser magnitude, the Medicine Bow crest being only from three to — four miles west of mid-valley. At the north this crest is a sharp and ragged ridge, but southward it becomes comparatively even and rounded in outline, a massive ridge, falling gradually until covered with lake beds near the junction of the Hast Fork with the Main Grand. The east- ern valley side retains its ruggedness all the way to the Hast Fork. The principal drainage of the latter area is that collecting into Grand Lake, and is by a system of the profoundest mountain canons. All this surrounding mountain region is of the archeean rocks, schists, and gneisses. The few dips and strikes that I had opportunity to actu- ally observe, together with the impression obtained from the style of weathering of the rocks, indicated that the valley might be a great syn- elinal, but this is by no means certain. The apparent appropriate uni- formity of form and slope of the valley sides seems hardly a product of erosion, but as if the general surface of the metamorphics had been cov- ered, as at the west, with sedimentary rocks, perhaps the Cretaceous, and "as if all had then been folded together to form an anticlinal over the Medicine Bow, a synclinal in the Grand Valley, the latter probably originally determining the course of the drainage, and hence of the greatest erosion which has since removed all of the sediments, but not quite yet destroyed the general impress left by the fold upon the harder underlying rock. All the main portion of the valley is occupied by a mass of morainal matter, (see Fig. 9.) Below where the upper cation portions widen Wy pe : A ag eo r ‘ sitions Sarah ch Bee A DTT aie Pay vitkes Gk 7 4 . é 7 1‘? a , see \ . “ ’ 1 v Li is 3 iy ~ ’ , 4; 4 et ‘ , a ie # ;? ) ‘ ¢ ; ‘ Re cd he 4 Piha i ‘ *, { id eT [7 a Mats é CP Rs | sn aoe ein ae x ? mer ib Dae ae sWibbatats ’ e . ve ee ri yronessi eal teesinieaner get 7 4 ) . ; a eees pa a nly mde lind . ’ * : xf 2 g ae j at. ‘| +4) {Ree Fig. 9. SKETCH MAPshowing the GLACIAL MORAINES in the Valley of Grand River near Grand Lake, MiddlePark. Sa — Ss — ————— Meadows ke. STUHES et GEOLOGY—VALLEY OF THE UPPER GRAND. 159 into the flatter valley, the bottom becomes a swampy, grassy meadow, between one and two miles broad. Some pretending gneissic masses show roche-moutonée forms. This meadow has a semicircular border at the south, where it is limited by a not very prominent, but well-defined termi- nal moraine, a a, (see figure.) Below this is a great mass of morainal matter, 6, with a well-defined southeastern border, ¢ c, indicating a medial moraine lying between the glacier which occupied the main valley, and that from the Grand Lake cations. The northern part of c, and the main portions of the mass b, are thrown into piles and ridges reaching altitudes probably 300 or 400 feet above the meadows. Its surface is exceedingly uneven, abrupt depressions, perhaps 60 feet in depth, existing here and there with no outlet, while the general tendency of the ridges is across the valley in semicircular forms, marking the stoppages and accumulation of the material from the surface of the slowly-retiring glacier. Several small meadows are scattered in the lower portions of thismass. The trib- utary cations of Grand Lake also contain, I am informed by Major Powell, equally strong evidences of glacier occupation, both in their erosion and morainal débris. A small terminal incloses the lower end of Grand Lake, while the lake itself, though’ not well éxamined, gave the impres- sion of occupying a true rock basin of deep ice erosion. From the west end of the spur just south of the lake an exceedingly well-defined lateral moraine (d) commences, and extends southward nearly two miles. Though probably over 800 feet high where it leaves the spur, it falls uniformly and evenly toits end. The southern end of ridge c is low but well defined. The North Fork cuts through it in a curious man- ner, bending back northward to run along the upper side of the termi- nal moraine, (e €;) also a low but well-marked ridge, through the eastern end of which the united streams pass. Below is a meadow, limited likewise on the south by still another but more prominent terminal moraine, (ff.) The eastern end of the latter moraine rests against a granite mass, while a small meadow lies below its adjacent portions. The upper end is rather confused with smaller side moraines. The cen- ' tral portion merges almost imperceptibly into the irregular morainal mass, (g,) which rises in low rolling hills and indefinite border from the flat terraced, sage-brush valley m at the south. All these morainal masses are covered with a scanty soil and a thick growth of pines. The latter have been blown down in all directions, often in great broad swaths, and as often partially burned, rendering passing directly across the moraines, without resorting to the little open, marshy meadows, all but impossible. Good exposures of their rocky contents are not numerous. So far as observed the boulders seldom retain well-preserved scratches, much surface disintegration having taken place. Indeed, such is the general rule with all the glaciated rock masses of the Rocky Mountains. The roche-moutonée form is frequent, but the schists and granites succumb early to surface disintegration, and there has not been, as at the Hast, a boulder clay or tuff to. preserve them from weathering. It is rather a curious feature that the Grand, instead of passing through the lower portion of the valley occupied by the morainal mass, (g,) has cut a canon through the higher rolling spur of hard archzan rocks, (h.) The Hast Fork of the Grand commences as a well-defined open gorge at the base of Arapaho Peak, and running about north 25° east for nearly six miles, it gradually swings around to a nearly westward course near its mouth. Throughout this course this valley is exceedingly well defined. The tendency is to a U rather than a V form, indicating, as well as the usual scoring of the rocks, its glacial origin. The massive 160 GEOLOGICAL SURVEY OF THE TERRITORIES. and rather uniform rocky slopes rise on the north to the rugged mount- ain mass of Long’s Peak, and are cut by several deep caiions, while on the south they emerge in great curves with the smoother and more pla- teau-like granite mass lying on that side. From the end of the massive spur, which comes down over this cation valley between two and three miles from its mouth, commences a great glacial moraine, as indicated at (tk) in figure. It is at first several hundred feet high, and presents a most rugged and uneven surface, with great irregular depressions and a tendency to a parallel ridge structure. Enormous boulders, many 20 feet upon aside, are found scattered upon its surface, while here, again, a maze of fallen timber lies around. Itis rather singular to see the Hast Fork cutting a rather abrupt passage through this mass at a point where it rises perhaps nearly a hundred feet above the stream on either side, while to the west the continuation of the main valley on to the Grand is perfectly free from obstructions, the soft surface soil rising but little above the stream. This fact would seem to have its explanation in the explanation of another singular fact, which is, that the main Grand, rather than follow the main open valley west of the granite mass J, has cut a rugged cahon through the latter as indicated in the figure. It would seem as if originally it had followed the former course, passing north and west of I, while the glacier, reaching to J, and being deflected northward by it, had a terminal moraine, -which was but the extension of the lateral, the glacier stream having its natural outlet northward through it at some point k. Certainly the outlet of the East Fork could never be at k, if the original course of the Grand was through I, as it is now, while it is inconceivable that the Grand should have selected the hard and higher spur J, in which to cut a channel, rather than the low depression occupied by soft sedimentary beds, except influenced by some abnormal cause. The cause that would seem to have deflected the Grand from the main valley to its present course would appear to be the flood of lava which has poured down from the region between Willow and Stillwater Creeks ; (see map at head of chapter, Fig. 8.) As will be seen later, many of the hills are capped with remnants of this lava, while at many points it occurs low down, as if occupying former stream beds. These remnants, as shown in the figure (9) prove that this lava stream reached to the granite /, and occupied as high a level asit, as indicated by the table-topped hill near by. The small mass of lava on / appears . to occupy a little caiion, probably that of a stream running from the granite mass on the south across J, northwestward to join the old course of the Grand. Thus dammed off by the flow of lava the accumulating waters rose in a lake, and escaping at the lowest point around the end of the lava, gradually wore out the present channel through the granite. At that time, the waters must have passed through the channel k, but there was. probably sufficient water present to also wear the outlet between the end of the moraine k and the rock J, as the lower portion of the cation through the latter was slowly cut. If this explanation is the true one, and the facts, so far as known, admit of no other, this lava is more recent than the older glacial phenomena. Some of the lava near by seems even still younger than that here shown. A few miles farther down the Grand a small sheet rests on the gentle surface-slopes of lake- beds, apparently so recent that erosion has not yet had time to throw it into prominence by the wearing away of the softer beds on which it. rests. Another point seems explained by the action above described. The small area m, lying between the Grand and Stillwater, west of the roll- MARVINE. | GHOLOGY—FRAZIER BASIN. 161 ing hill hk, and south of the morainal mass g, is occupied by loose gravel deposits covered with a fine dusty soil, which occur in a flat terrace, ris- ing about 50 or 60 feet above the main stream. Near the center of this area is a low ridge which much more resembles the lake deposits farther down the Grand. No exposure showing the actual relations between this ridge and the lower terraces was observed, but the general im- pression received was that the former was the older—a hill of erosion, surrounded by the more recent terraces. If so, the latter were probably deposited beneath the waters of the lake formed by the dam of lava, and filled up the previously eroded valley surface. The Grand, after leaving the small cation through the granite mass 1, flows out into a flat terraced basin, where itis joined by Willow Creek and the Frazier River, and which forms a portion of the most interest- ing geological region of the park, before describing which, however, we will turn to the drainage basin of the Frazier. THE FRAZIER BASIN. South of the East Fork of the Grand the westward mountain-slopes, as has been previously mentioned, are far more snvoothly contoured and gently molded than north of that stream. These massive slopes fall to the area about the junction of the Frazier and Grand, and form a low northern side to the upper Frazier basin. Southward, the lateral ex- tension of the same slopes, which retain their former characters, descend from the main divide and form the east side of the basin. Sweeping around westward they fall from the Berthoud Pass ridges northward to its southern border. The western border of the basin is more ridge- like, with accompanying hills; is much lower than the east and south sides, but retaining a rather even top. The James Peak group stand at the southeastern corner of the basin, Mount Byers at its southwestern corner. The natural outlet of this basin is at the northwest corner, where the surrounding granite ridge rises scarcely 300 feet above the river in a broad gentle divide, passing over into the basin of the Grand, and across which the Berthoud, James Peak, and South Boulder trails, after uniting, pass to the Hot Springs. The Frazier, however, has cut its outlet by a rugged and impassable cabon—about six miles long and several hundred feet deep—through the spur of metamorphic rocks a few miles east of this divide. All of these surrounding mountain-slopes are of the metamorphic crystalline archean rocks. Their contours seem to indicate a surface of former subaqueous denudation, covered subsequently with sedimentary rocks, which have not so very recently been entirely eroded away, leaving their impress still on the underlying rock surfaces. Indeed, some ap- pearances upon the western side of the basin would seem to indicate that patches of such sedimentary rocks may still remain, though they were not visited.* Glacial action alone could never have effected such wide-spread uni- formity of character. All the flat lower central portions of this basin, forming an area ap- proximately five miles in diameter, are occupied by sedimentary rocks which have been eroded into distinct though low terraces. The dis- tribution of trees is here quite marked, being confined to the granite Slopes, and apparently to above a certain level on the higher terraces, * Major Powell informs me that he found some small areas of siliceous sandstones, probably Cretaceous No. 1, thus resting on both sides of the western ridge of the Fra- zier basin. llas 162 GEOLOGICAL SURVEY OF THE TERRITORIES. though these pine-covered areas may, in part, be granite bosses rising above the surrounding beds. All the lower terraces and bottoms are free from timber. Between the terraced filling may still exist remnants of the sedimentary rocks which probably originally filled the basin. The only sedimentary rocks examined, however, were along its northern border. East of where the Frazier River enters its caiion, and along the stream, followed by the Boulder Pass road, there are a few exposures which the stream has cut out of the adjacent terraces. One, about a mile east of the caiion mouth, is between 60 and 80 feet high, and is composed of light-drab sandy. beds, weathering white, from ‘four to eighteen inches ‘thick, mostly somewhat indurated ; considerable clayey sand, and some lenticular bodies of gravel. Pebbles in the latter are of eneissic and granitic rocks, reaching two inches in diameter. Some of the sand is quite fine, with scattered pebbles, and some layers of grains of chaleedonic or agate-like quartz. The dip of all is from 5° to 10° to southwest. This branch of the Frazier River lies mostly in these beds, but at a few. points near the granites on the north it cuts through little southward-projecting points of the latter which are surrounded by the sediments. The lower river terraces have much sage-brush sprinkled over them. In the northwest- ern corner of the basin, from two and a half to three miles west of the cafion entrance, the low hill-slopes near the road’ show some dull, dark, somber, brown-colored sandstones of coarse texture, which dip 8° or J0° to the southwest. They are at first composed mostly of quartz and fieldspar, with some mica, debris from the surrounding metamorphic rocks; but farther on small pieces of red and whitish sandstone occur, erowing larger as one advances, till frequently one-half to one inch in diameter, and usually brecciated rather than rounded. They are prob- ably derived from the hard sandstones of Cretaceous No. 1, which occur farther on, and show tliat these beds of the Frazier do not belong to the older sedimentary series of the park, while their general characters indicate that they are very recent, probably the same as the usual lake beds, and derived from the rocks immediately around. The fact that these recent beds incline slightly is interesting. About three miles from the cafion the road passes from these beds to the smoothed granite region of the low divide, and passes over into another portion of the grand drainage, to which we will now turn. THE REGION IN THE VICINITY OF THE HOT SPRINGS. The region that willnext attract our attention is shown in the accom- panying map, (Fig. 10,) the relations of which to the park in general may be seen by glancing at the general map, (Fig. 8.) A section (A. B) across the same is given on Plate III, section 1, which shows, also, the character of the country lying north of the section. - It is but a mile or two after leaving the sandstones of the Frazier basin, across the low granite divide just spoken of, to where the road enters the lower side of the map. It soon divides the right-hand trail going to Grand Lake, the left-hand road continuing on to the Hot Springs. Following the latter a little past the branching, some of the recent sandstones, similar to those just left, appear upon the granites, followed by a small ridge of a hard white sandstone, dipping at an angle of 55° to the northwest. The exposure is small, and the outcrop was not observed extending toward the hiils to the southwest. Follow- ing along the exposure over the ridge to the northeast, and in the valley EN NARI NL le BO NRG wy mw we ’ Q brian eos ope Fig. 10. GEOLOGICAL MAP OF THE REGION * inthe Neighborhood of the Hot Springs and the Upper Grand; Middle Park. Ry \, \ \ Lv, = SUD s retaceous Dolentic Lienitic Granite ebc. Breccia. Formation. Lake-beds Basaltic (eee f ama and Alhwim Lava os SEALE 5) mues “yIeT O[PPI ‘Spvor sSaradg 4oxy pue oyvT puery oy} Jo uooanl oy] avon ‘ssulidg JOP] OY} JO YSvOT INOS SoTIM 104 TOIQDEG MOS N= ‘TL ‘Sta 480007 TON Snoaowqoag MARVINE. | GEOLOGY—VICINITY OF HOT SPRINGS. 163 followed by the Grand Lake road, a better cross-section is exposed along the road as follows: Section of Cretaceous No. 1, near junction of Hot Springs-and Grand Lake roads, entrance of Middle Park. Nature of strata. Estimated thicixness. Strike about north 20° east, dip about 35° northwest. Feet. LNIGMIG IER) Poe SS. cocces DaSsiGacoeyeeoser sat COCO DeSean DESAce BLAS A StS aCe 15 COWGIRL! 256 bose beso cococu opto cnne oaco bpeEEe qusces spacde Osbe oanes asoee 150 Sandstone, white and yellow, fine, gritty, siliceous, iron-stained- - 125 Covered, red soil, debris of soft brown sandstone, and near base of ‘purple. shalcland some limestone.« (ete Vite eNO ose) se ne 225 Sandstone, massive, white, some cream-colored, red blotches, siliceous, GUMINY o. ccgo eee seg c200 s0e5 Send secu sone ose Mipoono Dope nO na aDeatosEnac 80 med) Soe seen as sts geieasinanie DeCUSU Bona aaa UeU HOR Eee eaters 50 COMELCURGROM eee ermmiasteeeele as cal ceee aieeeains one amiemineie es cceiacis tris See ainsi 150 debris of brown sandstone and fine cherty finicatona NASON AE SS ae 100 — Ridge ; white, fine, gritty, siliceous sandstone, some cream-colored and red. 100 Covered, red soil, (red shaly sandstones?) 2... .--.-. -220-2 e2-e cece eeeccn-s 60 Coarse gray granite, considerable mica, obscure gneissic structure. Strike + north 35° east, dip 50°-80° southeast. This section would indicate a thickness of about athousand feet for those beds, and affords an example of the greater thickness which I suppose the lower Cretaceous beds occasionally attain. But ten miles to the north- west, at the Hot Springs, a thickness of only about 360 or 400 feet is in- dicated, butthe same general characters are there found ashere. Thelava forming the.top is composed of a dull, dirty gray, fine granular matrix, with numerous black, quite weli-formed crystals of augite scattered through the mass. It weathers a dirty brown, with narrow white seams two or three inches apart, parallel with the bedding, and speckled with black augite crystals, as well as by both rusty and “white- colored spots. It is probably a dike occupying the line of junction between the hard sandstones and the softer Cretaceous shales, which probably cccur im- mediately above, though they are not here exposed. At one or two other points in the park the weak point between the sandstones of No. 1 and shales of No. 2 have afferded a very natural outlet for erup- tive matter, and such is probably the case here. After passing across this section the Grand Lake road leaves the stream, and, turning tothe right along the outcrop, passes up a small valley, having the little ridge of dolerite lava on the right. From the lava ridge, and on either side of the main stream, is a ‘steep slope rising to the summit of a terrace. The channel of the stream passes into this, cutting a sharp V-shaped gorge, the east side of which rises some 50 feet higher than the general level of the west side. The material of this terrace thus cut through by the stream is coarse angular débris, of highly micaceous schistose gneiss, of the dirty-red and black-banded variety, and some granite. On the summit some large masses indicate that these metamorphic rocks are in place. These facets would indicate that a fault had been passed ; one which had thrown the outcrop of sandstone just described downward on the southeast side, bringing the granite upward on the northwest side, as in the accompanying section, Fig. 11, the position of which is shown by the line C D, Fig. 10. Passing on northwest, the coarse débris terrace is found to fall in 164 GEOLOGICAL SURVEY OF THE TERRITORIES. three pretty-well defined steps of about 90, 140, and 80 feet respectively, to a stream, on the opposite side of which is a low-terraced treeless park, about three miles broad, rising in rounded slopes to a ridge capped with a broken pallisade beyond. On the left (s southwest) the terraces abut against and run out from a hill which looks off in the same valley, and on its northern sides lie the same sandstones, dipping northwestward at an agle of 35° with the bed of dolerite lava on their top just as before. See section H, Fig. 10 and Fig. 11. Low terraces abut against the lava and run out occupying the valley basin beneath which, however, as we will see later, lie the Cretaceous Shales. The hill and region lying south of E was not.personally ex- amined, and, while the sandstones may mantle over it, it is apparently of granitic rocks as indicated on the map. On the right, also, and a few miles in an opposite direction to H, similar beds may be seen like- wise dipping westward beneath the main valley. Returning to the Grand Lake road and following it northward, it is found to pass over into the head: of another valiey leading down to near the mouth of the Frazier Cafion. On the right (east) i is the ridge formed by the edges of the sandstones resting on ‘granite below, and dipping down underneath the trail. Near the Frazier these edges overhang the canon and form the top of its western wall. Beneath the valley through which the road passes, however, the beds are flexed, forming a synelinal of the valley and an anticlinal of the ridge just west of it, (see section 1, or A B,) the western slope of which, just as at EH, dipping westward beneath the terraced valley. The mouth of the Frazier Canton is through the ridge of upturned sandstones, after which the valley opens somewhat, with terraced lake-beds before entering the main valley. he exposure upon the west side of the canon gave the following section (at B, section 1, Plate III.) Section of No. 1 Cretaceous at the mouth of the Frazier Caron. wah eth Thick- Nature of strata. Eas) eet Covezed hill-slope, inclining west, facing east, dipping west into bill 15°, very compact, hard siliceous sandstone, mostly white, gritty...--....--..-----.--. 40 Covered debris of brown sandstone, and compact blue-gray limestone .-.------ 80 Sandstones, reddish, thin-bedded, some shales ..---.-.-...---..----.--------- 25 Compact gray-blue limestone, somewhat cherty, blotched .---....---.-------- 2 Sandstones, in 2 to 5 feet beds, white to yellow pink shales.........--.--..---- 30 Covered, débris of snufi-colored and rusty brown sandstone..-...---.---.---- 85 Gray, rather granular granite, with but little mica, containing very large scat- tered crystal of feldspar to river. These beds are probably liable to considerable local changes, both in characters and thicknesses. They are probably the same as a portion of _ the lower beds of the preceding section, the higher ones having been here swept away by erosion, and being found west. Crossing the Fra- zier northward, station LVIII is found upon a hill of the siliceous sandstenes. Its surface has a gentle eastward slope, the sandstones dipping also east, but curving up again they are found lying as usual on the granites, thus forming a little synelinal. The upturned edges of - these sandstones are leveled off in a peculiar way, being evened off with tbe granites behindthem. (See section near B.) The west side of ee ee agree FT J cd ibe ae . ; a Lake Bcds, four miles southeast of junction of Frazier and Grand Rivers. Dip 10° east.—W. H. Holmes. Ree GEOLOGY—VICINITY OF HOT SPRINGS. 165 hill LVIII is abrupt, and shows in its upper portions the edges of the sandstones, with, at the base, some granite and gneiss beneath them and again, just west, but lying low in the stream, some of apparently the same sandstones, but cently inclining west. In other words, a fault passes at the west base of LVIII, in which the east side has been ele- vated, and which is probably the equivalent of the anticlinal just south, and the fault still farther south, near the Hot Spring road. The terraces mantle about the west and north base of LVIII, concealing its sandstones in these directions, but the main ridge of sandstones rest. ing on the granites continues on northward to the Grand River. The ridge is not prominent—the sandstones dipping steeper than farther south, reaching 45°—while from it the nearly horizontal lake-beds, which reach high upon it, sweep out between the Grand and Frazier Rivers in many long, low terraces. The ridge of Cretaceous sandstones is lost be- neath these lake-beds near the Grand, where the latter issues fromits short canon through the granitemass below where the Hast Fork joins the main stream (1) of ‘the map of the moraines of the Upper Grand. Thesandstone ridge does not appear lying on this granite, the lake beds surrounding it instead. At the north, and just without the map on the right, are the valley of the Upper Gran dand the south end of the Medicine Bow ridge. Near Willow Oreek and the Grand the lake-beds predominate also. The north side cf the Grand is lined pretty continually with two low terraces of white lake-beds lying from a quarter to a half mile from the stream, the country rising from them in long slopes, and rounded hills lying between it and Willow Creek. A fine, dirty, dark, basaltic lava lies at one or two points on the upper terrace, and appears also to cap the hills, while much of the terraces are covered with lava fragments and jaspery pebbles. The small patches of lava near the mouth of Wil- low Creek occur but little above the stream, and seem to cap low sur- faces, dipping gently to the northeast. East of these the larger area near the edge of the map is a mesa, or table-hill, capped with lava. (See section.) Ascending Willow Creek, the beds of the valley are apparently of the usual lake-beds. Where the dip of 5° east is indicated there occurs, among light-gray sandstones, white marls, and other beds, a more indu- rated bed of semi-compacted gravel, in the composition of which pebbles of lava, often scoriaceous and up to four inches in diameter, enter largely, as well as metamorphic rocks. While considerable false bedding occurs, the general dip seems to be 5° or 10° to the east, a little north. Just above, in some similar light-gray crumbling sandstones, a dip of 10°-15° northeast was observed. While the hills seem lava-topped, much basaltic lava here occurs in the valley also. At first a tongue of a dark, decomposing irregular lava touches the river from the north, but above the river is lined more continuously on the north side with a very irregular, red, brown, and black lava rock, often having the appear- ance of a consolidated mud. On the south, the rounded hills rise more abruptly, but still seem lava-capped. A little farther up the lava occu- pies both banks, and appears as if coming from an extensive flow on the north and east, the eastern tongues of which cap ridges running out to- ward Stillwater Creek. At the north rise hills adjacent to the Medi- cine Bow ridge, which show somewhat in the section, but which will be referred to later. We have seen that between the Frazier and Grand are the long, low terraces, and that they also occupy most of the area drained by the main tributary of the Lower Frazier, and that near the metamorphic rock, at one or two points, they are composed of coarse débris, with 166 GEOLOGICAL SURVEY OF THE TERRITORIES. some finer uncompacted sediments. Farther out they are of soft, crumbling, white marls, with surfaces usually sprinkled with bould. ers, often quite large pieces of metamorphic rocks, as remnants of a bed which had existed above the present surfaces, and had been eroded away. It wasin this neighborhood thatthe follewing section, Fig. 12, was observed and illustrated by Mr. Holmes, when accompanying Dr. Hayden’s party, and shows well the characteristic weathering of these soft beds when exposed, as sometimes happens, in a eliff. Here also is an inclination in these recent beds of 10° to the east. Thus, a greater part of the eastern corner of the map is of lake-beds, in part covered with basaltic lava, and at the east abutting against an outcropping fold and ridge of Cretaceous sandstones, which dip west beneath them, and rest on metamorphic rocks. They form a flat.terraced and treeless val- ley, but at the north and west rise in higher bulky hills. Just west of the junction of the Frazier with the Grand rises an abrupt, sharp, well- defined ridge, several hundred feet high, which is broken through by the river in a harrow gate-way. Just outside of this gate-way, at the north side of the stream, and directly beneath the ridge, there are exposed by the ravines cutting through the terraced lake-beds, a thickness of about 300 feet of brown concretionary, friable sandstones—the characteristic features of Cretaceous No. 5—and which yielded an Inoceramus and joints of Baculites. These beds dip westward beneath the ridge at an angle of 25°, The gate-way exposes the larger ridge to be composed of a rough, sedimentary aggregate of volcanic material; a series of con- glomerates, breccias, sands, and irregular material, of which the most distinct rock is of a doleritic character, consisting of a gray granular base, containing occasional small crystals of a trichinic feldspar, and more numerous, larger, and well-defined crystals of augite. This more compact portion is a similar rock to the lava dike resting in the siliceous sandstones near the entrance of the park. This volcanic detrital series attains an estimated thickness of from 800 to 900 feet ; the lower part being a massive accumulation, and not show- ing distinet stratification, the upper part being well bedded, and often of fine materials. These strike nearly north and south, and dip westward at an angle of 60°, though the higher portion of the’ ridge on the south shows an abrupt bend, dipping but 25° or 30° west, (see section.) Passing down-stream through this gate-way, the valley again opens out, but its character changes entirely. The beds that lie above the doleritic breccia and sands, though likewise abruptly turned up and dipping west immediately adjacent to them, suddenly become nearly horizontal, with a gentle northern dip, and form, all along the north side of the Grand, a series of regular and high terraces running in long tongues out toward the river. There are two principal terraces, the lower one rising nearly a thousand feet, and attaining this level between one and two miles back from the river. Harder beds on its face break up the front slope of this terrace, tending to mold its face into minor terraces two or three hundred feet high. The second terrace stands about a half mile back from the edge of the lower one, and rises in a more even slope, unbroken by intermediate beds, to an altitude of about a thousand feet above it. The accom- panying section, Fig. 15, gives an idea of the profile of these well-marked terraces, which attract attention even from Long’s Peak far to the east. Back a few miles rises still another terrace, estimated at about half the height of the last one, or about 500 feet. Hstimating that there were at this point about 100 feet of beds beneath the river, and be- Grand River Vie. 13. Section F' Profile of Lignitic Terraces on north side of Grand River four miles above the Hot Springs, Middle Park. [See sec. F. Fig. 10.] et NE, fi Mi AY LAE Dice Be = a Pier JOUER Fibi Voleanic Breccia Bed, one-half mile north of Grand River, above the Hot Springs, Middle Park.—W. H. Holmes. SIARVINE.] GEOLOGY—_-NONCONFORMITY AT HOT SPRINGS. 167 tween it and the volcanic breccia, there occurs here a thickness of about 2,700 feet of sedimentary rocks lying above the breccia bed. The ravines from the north cut deep into these terraces, breaking them up into promon- tories with squarish fortification-like fronts facing the river. Upon the south side of the river these features are far less defined, and here only thelowerand softer beds occur, while the northward dip increases. The valley, after passing the breccia bed, is quite open, the river being lined with much beautiful bottom-land. Below the gate-way some of the lava appeared to outcrop low down near the river, but its relations were not examined. These.terraced beds are of the characteristic lignitic group, and are very different lithologically from the undoubted Cretaceous beds lying below the breccia. Nearly ail the exposures here show them to be sand- stones, the more prominent ones, or those which give the terrace-form to the eroded beds, being mostly grits, quite coarse, often becoming con- glomerate, not very firmly cemented, and composed almost wholly of granitic and metamorphic débris, (except that the mica is naturally ab- sent,) while feldspar crystals, sometimes retaining much of their form, occur. The color is mostly somber dark brown, though some are quite white. Some finer and more compact beds occur, with occasional fossil leaves. In descending the Grand, the terraced beds on either hand are found to become slightly inclined to the northeast, amounting perhaps to about 10°, the river thus passing down through the lower .beds as before it passed up through these, until at about four miles in a straight line from the upper gate-way, another and somewhat similar passage is found by which the river again breaks through a ridge of precisely the same ma- terial as before. Itis, in fact, the same bed again appearing to view from beneath the same lignitic sandstones, the strike being about northwest and southeast, but the dip about 15° to the northeast, the bed there- fore being folded into a synclinal form, the east side being bent down- ward more abruptly than the western side. As before much of this series is massive, or wholly indefinitely bedded, and some compact lava occurs, as if of distinct lava-flows. The latter seems to be doleritic, crystals of augite being quite frequent, though some is more basaltic, being fine, and quite homogeneous. Most, however, is of a distinct congiomerate and breccia, some very coarse, of pebbles like the accom- panying lava, many scoriaceous, while much is of fine material, finely and evenly bedded. Their total thickness was estimated at about 800 feet at this point. The accompanying sketch, Fig. 14, of an exposure about half a mile north of this gate-way was made by Mr. Holmes, and shows the distinct bedded nature of this volcanic ash, &e. THE NONCONFORMITY AT THE HOT SPRINGS, MIDDLE PARK. Passing through the short break by which the stream cuts through this ridge, the western edges of its gently eastward-dipping beds are found extending northwest and southeast as a continuous line of black palisades which look down upon valleys tributary on either side of the Grand, that at the south being wider and flatter than the one from the north. Regarding for a moment the section found immediately along the Grand, (see Plate III, section 1,) there appears above the alluvium on the north side of the stream, and a little west of, and nearly parallel to, the breccia ridge, a hog-back like ridge of sandstones which dip at an angle of 25° or 30° northeast below the breccia. Some baculites were found 168 GEOLOGICAL SURVEY OF THE TERRITORIES. in the sandstones which are undoubtedly the equivalents of the beds that bear similar fossils and lie below the breccia east of the upper gate-way, and near the junction of the Grand and Frazier. It is Cretaceous No. 5. This ridge extends a mile or more from the river, gradually flattening and bending “westward. Following down the stream, nothing but river > allu- vium is ‘found for nearly a mile, - when, along its southern bank beneath the alluvium, there are exposed some 800 feet of black clay, shales, and slates, at first dipping up-stream only 20°, but increasing to 40° farther down. After passing these slates the river breaks through another ridge, but this time of the quartzite and siliceous conglomerates rising out from be- neath the shales, and, like them, dipping 36° up-stream. Behind the first ridge some small longitudinal valleys, with minor ridges of quartzite and siliceous conglomerates with dip lessening to 20° occur, while from 600 to 700 feet below, where the quartzite hog-back is first met, the river passes into a cafion cut in a smooth-tepped mass of reddish granitic gneiss, thus giving an actual thickness for the quartzite series of about 360 feet. These beds are the Cretaceous No. 1, the shales above being. No. 2, while directly on the line between the two issue the well-known Hot Sulphur Springs of the Middle Park. From the granite, upon the eastern edge of the map, to the granite below, the Hot Springs upon the w estern edge, the line of the “Grand River passes, therefore, directly across, at least so far as the granites, the Cretaceous, and the volcanic breccia bed are concer ned, a synclinal fold, the eastern side of which has some minor fiexures, (see section.) Not so the lignitic beds, however. Immediately above the Hot Springs, ’ Mount Bross rises abruptly for over 1,500 feet. It is composed through- out of the characteristic lignitic beds, mainly coarse grits and sand- stones, yellow, gray, and white, with laminated arenaceous shales, which contain many fossil leaves, barely, if any, disturbed from a hori- zontal position. Though direct contact between these and the Creta- ceous in the river at their base was not observed, the position of the mountain is such that its beds must rest unconformably upon the up- turned and eroded edges of the Cretaceous sandstones and shales below. As may be seen in the section, the tops of the great terraces above the lower gate-way of the Grand sweep in long slopes up to White Face Mountain, which is also composed of the lignitic beds, slightly inclined and capped with recent basaltic lavas, which will be spoken of later. The southern face of the mountain is steep, and beneath it the north- west extremity of the breccia ridge disappears. Around the latter appear to sweep the lignitic beds, and to connect directly by a high ridge the west spur of White Face with Mount Bross, throughout which ridge the lignitic strata appear nearly, if not quite, horizontal. The western end of the hog-back like ridge of No. 5 sandstone, about a mile above the Hot Springs, likewise seems to disappear beneath the eastern side of Mount Bross, apparently surrounded by its horizontal beds, as. is the end of the breccia ridge by the similar beds of the White Face mass. Mount Bross itself shows an indistinct terrace form, though not well pronounced, and its lower terraces in the west run out and appear to quite cover the quartzites of No. 1,if not to reach to and rest directly upon the granites beyond. These facts clearly show that here was a local folding of the rocks which occurred before the lignitic formation commenced to be laid down, and probably close upon the completion of the deposit of the friable and concretionary sandstones which have been designated as No. 5. Closely connected with this folding, and probably an effect of the same cause,, was the eruption of the material which forms the breccia-bed. S25 7 Diagram section at the Hot Springs, Middle Park, to Fig. 15. show the probable section after the erosion of the Hot Springs fold and before and during the deposition of the Lignitic Beds. " wa 5 ; { t 4 GEOLOGY MARVINE.] NONCONFORMITY AT HOT SPRINGS. 169 As the Hot Spring fold gradually rose, the edges of the Cretaceous and of the breccia must have been eroded back to where the latter was nearly horizontal, before the lignitic beds were deposited upon. their edges. This state of things is shown in the following diagram, Fig. 15, in the western end of which, near the springs, the dips are as they now exist, indicating the flexure to be as shown by the dotted lines: Since the Eocene beds in and on the west side of the breccia synclinal are inclined eastward with the breccia slightly, some movement must also have taken place since their deposition. This probably occurred at- the same time that the east side of the synclinal was upturned, which obviously took place after the lignitic period, for upon this side the lig- nitic beds are everywhere upturned steeply with the breccia and Creta- ceous below. This was at the great mountain-forming period, when the greatest recent folding of the Rockies occurred. It was at this time, probably, that the rocks of No. 5,.as shown in the hog-back ridge above the Hot Springs, were inclined from a flatter dip to their present dip of 25° or 30°, while this later fold seems to be also indicated by a very gentle anticlinal appearance beneath White Face Mountain. Let us turn to the evidence of this unconformability between the Cre- taceous and lignitic south of the Grand River. The Grand flows close to the southeast base of Mount Bross. On the south side of the river there is no corresponding eminence, the tributary from that side of the stream occupying a rather flat and open valiey. The edges of the breccia ridge line this valley on the northeast, and following them along they are found to swing eastward and then northward, joining the southward extension of the upper breccia ridge of the Grand. In other words, the breccia outcrop is continuous throughout, showing the fold to be a synclinal, with its axis dipping northwest, thus exposing the edges of the bed in the form of a great spoon, with the point directed southeastward, and filled with the lignitic beds in terrace form, the eastern side being bent up much steeper than the western one. The map shows this clearly, while it is far better presented pictorially in the accompanying sketch, Fig. 16, made by Mr. Holmes from points upon ‘Mount Bross. The terraces and breccia palisades, with the many pic- turesque accessories of the region, as seen from this point, form a very interesting as well as beautiful view. Thus the lignitic beds do not lap over and cover the edges of the breccia south of the river as they do between Mount Bross and White Face south of it. South of the valley, and opposed to the breccia palis- ades, however, the lignitic again occurs, the edges of the nearly horizon- tal beds appearing on the rather steep slopes leading up to station LIV. From this point the spurs of the LIV ridge extend westward toward the granite cation below the Hot Springs, showing very indistinct terrace- forms, but sufficient to indicate a very nearly horizontal bedding throughout. In the valley, at their northern base, and southeast of the springs, however, are two or three ridges of cretaceous sandstones out- cropping from the otherwise soil-covered valley. These dip eastward toward the breccia ridge, and trend toward the lignitic mass on the south in such a way, and approach so near to it, that, though no direct con- tact was seen, they must pass unconformably beneath it, (see sketch.) Two or three miles west of these ridges, and nearly a mile west of where the quartzites of No. 1 would appear to pass the lignitic beds, and but little south of the caiion, the western extension of the LIV mass shows the characteristic coarse brown sandstones of the lignitic in a precipice two or three hundred feet high, dipping 10° or 12° to the south. These sandstones must here rest directly on the granite. \ 170 GEOLOGICAL SURVEY OF THE TERRITORIES. What appeared to indicate unconformability occurred at one other point. Leaving the Hot Springs and following the road southeastward, we pass over a gentle saddle, having the breccia palisades on the left, and the lignitic rising to LIV on the tight, and proceed on to where the road first enters the portion of the park that we have been considering. Standing upon the outcropping ridge of Cretaceous quartzites, E, before described, and looking southwestward, there lies on theleft abilly: region, apparently of the metamorphic rocks, and upon the right the flattish valley oveupied mainly by terraced lake-beds. Across the line of vision extends the ridge on the northern end of which station LIV stands. From the station the top of the ridge lowers very slightly in going south in a long convex curve, rising in about six miles to a somewhat higher point. The whole east face of this ridge is steep, and shows the edges of the lignitic beds which compose it, ‘and which dip, like the top, very gently south at the north end and north at the south end. ' Atthe small notch which ends this part of the ridge at the south, the contour of the ridge changes, and all the rest of the way on up to Mount Byers, of which it is a continuation and spur, it appears to be of the metamorphic rocks. In the line of vision, however, at the base of this ridge, and near where the lignitic appears to rest on the metamor- phic, is a small ridge like the ridge EK, and apparently of the same rock outcropped in the same manner. If so, the Cretaceous quartzite would here also pass unconformably beneath the but slightly-disturbed lignitic beds. I have already expressed the uncertainty of the nature of the hills lying southeast of the point last mentioned and H, and border- ing the west side of the Frazier basin. Some ridges here are not decid- edly of metamorphic outline, but may contain patches of the Cretaceous quartzites with which, as before remarked, the contour of the spurs would indicate that they were once all covered. In the low region near the point of the breccia “‘ spoon,” and near E, are a few small hills or ridges of doleritic lava, like that composing the breccia bed. They appear irregular in their mode of occurrence, not bedded, but more like dikes. Precisely the same lava has been men- tioned as occurring on the summit of the Cretaceous quartzites in sections C, D,and EH. It would appear as if these were quite likely the points of outlet for the material which composes the breccia bed; that above them at the then surface of the country were actual rents, possibly volcanoes, from which issued the lava and ash and breccia which now lie between the Cretaceous and lignitic beds. If so, these rents have been most completely swept away by erosion, part of which quite probably taking place immediately after the deposition of the main portion of the bed, and before covered with the lignitic beds, for some of the lower lignitic beds in the breccia “‘ spoon” contain voleanic débris along with their — usual metamorphic constituents. Moreover, the breccia thins in going northward, the thickness where it crosses Willow Creek being less than where it crosses the Grand. WILLIAMS RIVER VALLEY. T'rom the western side of the lignitie portion of the LIV ridge, its indistinctly-terraced spurs appear to break off indefinitely into the val- ley of Williams River, but whether the beds dip gently down beneath the lake-beds, which occupy all the iower parts of this valley, was not ascertained. The Grand, after cutting an irregular cadon through the flat-surfaced granite mass below the Hot Springs, enters this lake-bed region about Cretaceous, ec. It. Bross, Middie |: Park. enclosed Lignitic Beds, ei Dolerie Breccia, b. CGrotaceors, ¢. fneinsio-sranite, ye. View east up Grand River from Mt Bross, Middle Park. Showing the Breccia husin and enclosed. Lignitic Bods, ete. baat a GEOLOGY—NORTHERN LIGNITIC AREA 171 four miles below the Springs. These extend in broad terraced surfaces far up the Williams River Valley, forming all the flat lower and treeless portion of the valley. The southern and eastern borders of the valley appear to be wholly of metamorphic rocks, which rise in massive spurs and slopes to the Mount Byers ridge; and though the upper cafions of this drainage cut deeply into these rocks, a uniformity of contour is pretty well preserved among the great spurs. Though not examined directly, some appearances on the eastern border of this valley seem to indicate the presence of the lower Cretaceous beds resting on the arch-. ean rocks. The western side of the valley is of the lignitic beds which compose the Williams River Mountains, and which dip gently north- eastward and probably beneath the lake-beds of mid-valley. At the south a great north and south fault occurs, in which the west side has dropped several thousand feet, leaving the metamorphies on the east and the lignitic on the west. The fault probably dies out in coming north. It will be referred to more in detail when speaking of the geol- ogy of the Blue River Valley. The details of the Williams River Valley were not studied. THE NORTHERN LIGNITIC AREA. The lignitic beds which have been described as occupying the ‘ brec- cia basin” above the Hot Springs, and as lying unconformably upon its western arm as well as upon the Cretaceous below in the nearly hori- zontal beds of Mount Bross, spread out in their northern extension, and form the greatest continuous area occupied by any one geological forma- tion expressed upon the map, except that covered by the archean rocks. Throughout this area, except along its eastern edge, the rocks are but very slightly disturbed, their inclination being generally less than ten degrees and being in various directions, though mostly northward. Though the region asa whole is one of elevation, its surface is uneven and rises in tour principal masses, which stand high above the interme- diate country. This unevenness is due wholly to the.erosion having eaten farther down into the mass of nearly horizontal beds in certain areas than in others, and this erosion has been thus directed along these channels by the intrusion of eruptive rocks rather than by more pro- found structural causes, as folding, &c. The southernmost and lowest of these four elevated points is the White Face and Coral Peak mass, lying a few miles north of the Hot Springs, which has withstood erosion better than the surrounding country, and hence retained its elevation in virtue of the protective cap of hard basaltic lava which here covers the softer lignitic sandstones. The divide between the middle and north parks is also naturally elevated, but it attains special height at two points: one, Park View Peak, which, though higher than any of the others, is composed of a smaller mass, and hence has more abrupt slopes; and another, the great mesa-like mountain mass lying west of the Park View, and between the head-waters of the Troublesome and the Muddy. This latter elevation is due to a great capping flood of basaltic lavas covering the lignitic, while Park View and the divide adjacent, though having no lava-cap, is intersected by great dikes of porphyritic tra- chyte, which give to it its sharpness as compared with the other and lava-capped masses. The fourth elevated mass of lignitic strata is the high and exceedingly even-topped ridge which is almost completely sur- rounded by Willow Creek and its principal eastern branches. Though unvisited, this ridge appeared to be caused less by the presence of erup- tive rock than by the fact that the drainage, and hence the erosion, had 172 GEOLOGICAL SURVEY OF THE TERRITORIES. been directed away from it because of its being somewhat upturned against the Medicine Bow ridge of metamorphic rock lying just east of it. From these four masses the country descends in slopes, which are broken up into innumerable small ridges, to the main drainage of Wil- low and Troublesome Creeks. ‘There is a tendency throughout to a ter- race form, but nowhere is it so pronounced as in the breccia “* spoon” above the Hot Springs. Just north of the White Face group, this is partially due te the gentle northward dip of the beds, the inclination of the surface being in the same direction, while the northern part of the region is in the upper portion of the lignitic series, where there is less difference in the hardness of the beds, and hence less opportunity for the erosion to create terrace forms. The tendency still exists, however, the form of Park View being very graceful, the steeper slopes running out in flattish spurs to become rather abruptly steep again, but not at- -taining escarped edges. The valleys of the Willow and Troublesome, therefore, show forms characteristic of the geology of this lignitic re- gion, and are very different from the forms of valleys elsewhere in the district. Nowhere in the lignitic area are the streams bordered by low, flat, terraced banks like the lake-beds adjacent to portions of the Wil- liams River and the Grand, nor do they flow in sharp-cut, rugged calbons, aS in archean areas. Instead, a bottom usually but a few times wider than the water-course accompanies the streams, often marshy from the presence of beaver-dams, but not terraced, from which steep slopes rise on either hand for several hundreds of feet in escarp- ments which show the edges of the harder sandstones, with lesser slopes of softer beds between, and finally merging by curves, rather than abruptly, into a pretty general terrace-like level, rising on and on, per- haps, with other indistinct terrace steps to the higher masses beyond. In the Eastern or Willow Creek ridge these slopes run quite evenly to the top. In the White Face mass the last slopes up to the lava are abrupt and lined with some palisades of lava. The slopes up Park View are steep but graceful, while the western mass is surrounded by great palisades of black lava, white volcanic tuffs, and conglomerates eroded into pinnacled forms, and looking down into the upper cations of the Troublesome. The southern border of this great lignitic mass as it occurs near the Grand River has been already described. In ascending Willow Creek from its junction with the Grand, and after passing through the rounded hills of lake-beds, most of which dip gently eastward, and the accompanying basaltic lava, as before described, there is found crossing the stream about eight miles from its mouth the same ridge of dolerite breccia that crosses the Grand at its upper gate-way. About half a mile before reaching the principal ridge, however, an outcrop of similar material (breccia, &c.) is found on the east side of the stream, dipping 20° to the northeast, and just beyond and between the latter and the main continuous breccia ridge, which dips 60° to the northwest, are several outcrops; also, on the east side of the stream, of Cretaceous No. 5, here containing many fine cretaceous fossils. The upper outcrops near the main ridge dip 20° northwest, but following along them northeastward, they swing more and more east, dipping north 10°, and appear as if they swung around to become con- formable beneath the lower occurrence of the breccia. The dips are given in the Hot Springs map, (Figure 10,) and would seem to indicate a small local anticlinal, with the axis dipping north. These beds were not directly traced farther northward along their outcrop. The main breccia ridge, however, after crossing Willow Creek, appears to pass = GEOLOGY—NORTHERN LIGNITIC AREA. 173 along the eastern base of the high, even-topped Willow Creek lignitic ridge. The line of junction of the sedimentary rocks of this ridge and of these beneath it, with the metamorphic rocks of the Medicine Bow ridge, must lie along the valley between the two ridges. Unfortunately this was not examined. The facts presented near the Frazier and Grand Rivers, the apparent gentle westward dip of the Willow Creek ridge, and the smoothed ap- pearance of the west slopes of the Medicine Bow ridge, would all seem to point to the fact that all along between the two ridges the Cretaceous underlying the lignitic, together with the breccia between the two, are abruptly turned up against the Medicine Bow ridge, dipping steeply westward away from it. From Park View appearances seemed to indi- eate such upturned ridges of rock coming out from behind the north end of the Willow Creek ridge, lying along the base of the Medicine Bow ridge, and passing on north into the North Park. The narrow- ness cf the valley between the two ridges, as well as the apparently slight western inclination of the lignitic of Willow Creek ridge, how- ever, May indicate that a great fault lies between the two ridges, sepa- rating the archzan on the east from the Cretaceous and lignitic forma- tions in the west, the down-throw being upon the west side. Sucha structure is by no means improbable, as the tendency of all the folds throughout this region is to an abrupt western down-throw, which often passes into a fault. Where Willow Creek breaks through the doleritic breccia-bed the latter forms a well-defined ridge a few hundred feet high, striking a little east of north, with irregular curving, and dipping west about 60°. It is here only about 500 feet thick, and considering its greater thickness near the Grand, it is probably thinning in going northward. Passing up the Willow through the gap formed in the ridge by the stream, a small, sharp valley is found on either hand behind the ridge, with some exposures of soft brown sandstones, mostly shaly, dipping 60° west. A thousand feet beyond, a ridge parallel with the breccia ridge is passed, which is composed of coarser and harder brown sandstone, mostly of granitic material, like the lignitic terraces of the Grand, dipping 50° westward. Two or three hundred feet farther on a smaller ridge shows a dip of about 40°, and but little over half a mile above the breccia ridge, the dip is reduced to five or ten degrees, or even less. Here the dip is more across the river to the north than up it, the valley being a partial monoclinal, though the dip is very gentle. The terraces near the stream are somewhat marked, but best so on its northeast side. The first slope is between four and five hundred feet high, quite abrupt, in escarpments of coarse gray sandstones, some rather finely and com- pactly banded, and conglomerates, all of metamophic débris, sometimes 30 feet abrupt, with slopes of 5 to 10 feet of softer shaly beds. Some exceedingly fine, compact, dark-blue argillaceous bands occur, carrying Small black spots of carbonaceous material. Dips of 5° to 10° or 12° generally occur, mostly to the north, the observer constantly rising through the formation in going up the stream. Ata point about south- east by east of Park View, however, a dip of about 10° to the south: occurs along the stream for a half mile, ending at the north in a dip of about 30° to the south, till the up-throw of the beds on the northern side is perhaps 150 feet, when the gentle northern dip is again resumed. About in line with this small southward-bending fold, and perhaps a pro- longation of it, there occurs upon the southern spurs of Park View Peak, a short south dip of about 15°, but the usual northern dip is here, like- wise, at once resumed. In a spur just northwest of Park View, the re- 174 GEOLOGICAL SURVEY OF THE TERRITORIES. verse may be observed, a northern dip of 25° being observed for a short space, but soon flattening to 10° again. The whole slope north of Park View seemed to indicate a continuation of this northern dip, carrying the lignitic beds down into the low flat basin of the North Park. To the west the abrupt palisade edges of the great lava-cap covering the lignitic in that direction show, extending in a high promontory north- ward into the North Park; and here, also, a gentle northern dip seemed to be apparent at a few points. Though a large dike and several smaller ones occur in Park View Mountain, their connection with the topography is best shown in a hill northeast of that mountain, and across the westernmost fork of tne Wil- low from it. These dikes vary from 5 to 30 feet in thickness, some being apparently over five miles in length, and extending across the country like huge broken walls. Where several intersect or occur near one another, their combined resistance to erosion has formed a hill, every spur of which contains a dike. Between the two mountains is the pass for the Willow Creek trail over into the North Park. The accompany- ing sketch-map, Fig. 17, shows the forms of these two points, and their connection with the dikes. There are probably several large dikes upon the northern spur of Park View, and on the hills to the northwest, which are not indicated in the map, as they were not clearly seen. The dikes are of a very handsome porphyritic trachyte, a grayish green micro-crystalline or granular paste containing, as the more noticeable ingredients, numerous large, well-formed crystals of white orthoclase, and short, well-formed, hexagonal erystals of a soft, dark- green chlorite.* The lava capping Corral Peak has some peculiar features which should be mentioned before leaving this lignitic area. The summit of the mountain is a squarish, rugged mass, rising precipitously at the southwest end of a ridge that runs about three-quarters of a mile northeastward from it, where it is crossed at right angles by an equally long but excessively sharp ridge, trending nearly northwest and southeast. This whole top descends steeply, especially on the | northwest and south sides, for several hundreds of feet to the lignitie - beds on which it rests. The northeast ridge, though not examined at its base, appeared as if it were the dike through which the eruptive matter found its outlet. This ridge rises a little higher than the broader neck connecting it with the main point which rises some 500 feet above either. The sharp ridge and all the main top is composed of a dark, nearly black or brownish-black, brittle basalt, which pos- sesses a resinous luster on a fracture face because of the very large proportion of olivine permeating the mass. This lava weathers very peculiarly, breaking in thin flakes or slabs, sometimes shaly, usually standing nearly vertical, with flat conchoidal faces, which meet along the edges as do the facets of a cut-glass tumbler. These slabs are highly phonolitic ; and in weathering, the surface sometimes looks like a red- dish, even-grained sandstone. The columns which compose the western precipice are remarkably well formed. Some of them are two or three feet across, sharply cut generally into five sides, cross-jointed into lengths of from a few feet to a few inches, with, on the upper surface of each joint, an exceedingly well-formed convex spherical surface, rising two or three inches above the surface of the joint, and with its circumference nearly tangent to the sides of the joint. A _ corre- *It is intended that a proper chemical examination of this lava, as well as of all the volcanic and other rocks that requireit, shall be made to be used in the final report of Colorado. aay ane , ap) p & S ee Uf Sits ECM SC: | ESN 7 2 et AG Os “ I, oe : Z | po os ey, a CASS, 957 ‘ 6565 spot see cdo ses poe suo roocopeee 6 100? SLAY RIES Snag BanoGe 4obece Gabo DOO OCH GOES ee SEO noe Cae SES ACS MCe eee eeIseEs 200? CTRDIS WRONGUO coscdcescac hous dédgb05500 boUSb0 Odoa05 adenos poneae Baa ben cane 100? SUMIG poncedoo dedangcbond agen cea Seon S009 GNco ne osInasu POs sdOnE eae aera epee 25 ERG D cd SS RRSS oR ESB Gn Spne AR a SOC OU eneO RDA ape ne SOF Ne a aH Se aeiiaet iar 110 Slates, mostly shaly, very fine, blue-black, at center heavy bedded to 18 MEhes pune yenandubroken| surlaceeesspy-\s\= teen = elses iol cie esters caeieeee 120 Trachyte ; somewhat porphyritic, but mostly fine, irregular, and some scoria- ceous; breaks of one and two feet across slates..-......---.---.------s-- 10 1MN® SII GSis bo ssoodaesdosuoseooecoauGouS ce bec CHa SS nob Sapp oe ane uereeeeee 60 Limestone, fine, compact, dark blue; beds eight inches thick, subjointed to ShiahywhEthle my paru Shales below aes nes ere stn eeietecie eee sa cele eer 10 PU Ae In heise pet aa esate ts nisinis Syatere codes nile mt clahe sie Cire sietelo Win ejala ere sys ieizimiai s micio, scisicje cee 80 SINGS S.C SS TUTE) SEES RES OR Re SoS cn O RSE SC OOG RSS ee SO mets aoa Aas Hemmrsey 100 PREACH VLR ss sss. le osice we ccine sacle teees Be ionin sient ctaniin ae eins oe eis eeeie aan 275 Sa OW tats ete fo cra Neveratcinis aewials c/ainia taints ie wlelowmieine cee ote Ree abe te ale aie ame 20 LENO Sad os cn Se BOas DH e OSB COCOA GOODE TEE OCD IG OO EES cnt ep yn Sete a amen 150 MUI CEOUS SAN UStONE-nwihllep se sa Nees cio aie ey seine seic(ae ee e\ciascuee de = 80 River. Across the valley, eastward from the hill above described, on the west face of the Williams Mountains, is a little projected ridge, apparently a short dike, passing through the lower beds of the mountains. It is indicated in section 5, and modifies the section of the range, here near its highest point, by causing the lower bed to run farther out in a ter- race form than in the usual mountain section, which shows the west face as steeper, and more as in the dotted line. A few miles south, in a steep east bank of the main river, a vertical trachyte dike was observed, about a foot thick at the base, thinning to nothing about 80 feet up, and so disappearing before reaching the surface, on which no indications of it existed. THE PARK RANGE AND BLUE RIVER MOUNTAINS. Meanwhile, the Park range has undergone some change. ‘The rounded ridge has gradually risen until, near the base of the abrupt slope up to its southern extension as a rugged range, it is at the timber- line. The Cretaceous sandstones, resting on the ridge, are here cut up more than nearer the Grand. A remnant caps the very summit of the ridge, but greater erosion has cut much of the sandstones away, leaving the valleys inthe granites. Much of this erosion has been glacial. The valley, which has the steep and rugged slope of the northern ridge of the mountains rising from its southern side, and the more even-con- toured massive ridge on its northern side, i. ¢., the first valley north of 188 GEOLOGICAL SURVEY OF THE TERRITORIES. the greater mountains, is a glacier-cut gorge, widening and narrowing, with many glacial lakes scattered here and there, while its whole bot- tem is a maze of uneven roche-moutonée, which frost and vegetation are now fast breaking down, and gradually obliterating. It has cut deep into the granites, apparently leaving the Lower Cretaceous sandstones bordering the northern edge, and, farther to the east, where the main ridge falls to a lower and flat-topped spur, the southern edge also. Lower down, where these flat-topped spurs fall off rather abruptly, mo- rainal masses run out from their ends on either side, and, first running down the valley, finally cross it and join in a bulky terminal mass _be- low, which covers the granite, and then hides the upturned edges of the lower sedimentary rocks. One or two of the valleys draining off the rolling Park ridge north of this one present some similar features, being cut through the sandstones and exposing much metamorphic rock. About midway of this ridge, toward the Grand, a higher point presents some of the characteristics of a lava mass. It is probably basaltic. THE BLUE RIVER OR MOUNT POWELL GROUP. The Park range, after its abrupt rise from the broad rolling ridge at the north, entirely changes in its characters. It appears to be a rectan- eular-shaped mountain mass cut into the most profound amphitheatral headed gorges, which are separated by the most rugged and sharp saw- like ridges of rock imaginable. The main ridge lies along the south- western side of the mass, and from it the valleys and their sharp sepa- rating ridges trend in a general northeast direction. The northernmost spur was composed of a very distinctly and evenly bedded series of schists, gneisses, and granites which had a strike nearly with the ridge, and a dip of 40° or 50° to the southward. Looked at from the east, the general impression is received that all of the large ridges of the range have a similar structure. These rugged ridges, in their easternmost portions, (see Plate III, section 6, west end,) present a pretty uniform general elevation, (a b,) and as the northern ridge expands at its end into an even-surfaced table-like mass of rock, the impression is given that all of these sharp ridges are but the remnants lett from the cutting away of a plateau-like step which once followed along the mountain-face. These ridges also end quite similarly along a pretty straight line, and descend to rather a uniform level. Regarding now more particularly the north- ern ten or fifteen miles of the high range, which includes but four or five of the ridges, it is observed that at the base of each steep end, the low- ered spur does not continue on as a sharp ridge, but slopes off, a flat-sur- faced, plateau-like area, descending gently eastward, (c¢ d, section 6.) Since upon the corresponding area at the base of the northernmost ridge great quantities of debris of the Lower Cretacerous sandstones were found, abundantly proving that they covered the area, it appears that all of these flattish areas either are now, or have comparatively recently been, covered with the same sandstones. Such features would seem to indicate that the Cretaceous had once extended high up, or quite over the whole range, and that the latter, in its upfolding, had received the most pronounced uplifts along certain well-defined lines, the intervening portions not being tilted up at high angles. It is by such a process that the front range, at least from the Big Thompson to the South Platte, has received much of its uplift. Major Powell and Mr. Gilbert have noticed similar folds in the Kaibab plateau and adja- cent regions on the great Colorado plateau of Northern Arizona, through \ marvin.) GEOLOGY—SOUTHERN END OF WILLIAMS RIVER RANGE. 189 there the sedimentary beds have not (by many a thousand feet) been stripped by erosion from off the underlying rocks. Itisaform of mount- ain-building, which I think is not uncommon in the West. The caiions issuing from the high Park range, or Blue River Mount- ains, are glacier-scored, and cut deeply into the metamorphic rocks between the supposed Cretaceous covered areas, which lie between their mouths. From the edges and ends of these areas commence the moraines, which extend valleyward and end in broad indefinite morainal masses, reaching nearly to the river. The metamorphic rocks exposed in the caions probably extend some distance down them, and finally be- come covered by the moraines, encroaching on it from either side before the edges of the Cretaceous sandstones which underlie the main valley appear crossing the stream-bed; these edges apparently being covered by the moraines, as indicated by section 6. In this section the plateau area c¢ dis not shown quite high enough to be in its proper relation to the moraine. From the lower surfaces of the moraines the terraces sweep off to the river, the upper terraced beds evidently lying directly on the mo- rainal mass; the two formations being probably to a certain extent contemporaneous. THE SOUTHERN END OF THE WILLIAMS RIVER RANGE. Opposite the portion of the Blue River range last considered, lies the southern end of the more symmetrical portion of the Williams River range, which terminates at a saddle at Pass Creek, its highest point being nearly midway between that stream and the northern end of therange. The Blue River bends near this point, the valley turning from a southeast to a south course, in going up stream. Looking down the valley from a point above the bend, the eye sees, then, the southern end of the Williams Mountains, (see section 6, east end,) with the edges (x, x) of the prominent upper bed of the range running across it. AS shown in the section, it seems to be folded or faulted somewhat. On the south side of Pass Creek is Ute Peak, rising some 3,800 feet above the Blue. This mass shows as somewhat offset to the east with respect to the Williams Mountains. Its western face is terraced like the west face of the latter, the uppermost bed appearing running prominently across it, with the lower promi- nent bed showing on a portion of the face, and both dipping slightly eastward into the mountain, but all the mountain summit is of the metamorphic rocks. There are here mica, schist, and gneiss, rather finely banded, but somewhat distorted or irregular, with some felds- pathic seams, the strike being about north 10° east, with a dip vertical or high to the south. Its eastward slopes carry one at once into a country characteristic of the archean rocks and different from the valley just left, the first eastward descent being directly to the deep cations of the Upper Williams River, and then on aud up on to the massive, deep-cut spurs leading to the Mount Byers and Gray’s Peak groups of mountains. To the south all seems likewise a mountainous region carved from the hard metamorphics. The western face of the hard archzan rocks, which form the summit of the mountain, is abrupt for about a thousand feet down to the uppermost layer of the sedimentary rocks. Close to the base of this steep upper slope some of the sediments dip slightly away from it, but their inclination just abreast of the peak is mostly toward the latter, at an angle of 8° or 10°. There passes through 190 GEOLOGICAL SURVEY OF THE TERRITORIES. here, therefore, a great fault, which separates the sedimentary rocks of the Blue River and Wiliams Mountains from the metamorphic rocks of the peak and the region at the east, the down-throw being on the western side. The sedimentary rocks which form the valley and lower portion of the peak cannot be taken at less than nearly 6,000 feet thick, probably much more, while the schists of the peak rise more than a thousand feet higher, so that, making no allowance for an unknown tbickness of material eroded from the summit of the peak itself, the western side of the fault must have moved down, with respect to the eastern side, a distance of at least 7,000 feet. This great fault passes northward east of the Williams Mountains, but was observed nowhere along the Grand, and probably dies out in that direction. Southward it appears to form the eastern side of the valley of the Blue for some distance, while it may be the northern con- tinuation of some of the great faults that occur in the neighborhood of — Mount Lincoln, but the connection was not traced out at all. The beds which make up the west side of the peak are in part the same as those of the Williams Mountains. At the base, but best ex- posed on the north side of Pass Creek, or in the south end of the Wil- liams Mountains, are the series of somber, dull-brown sandstones, ex- ' posed in several heavier beds, with narrower, slatier beds between, which lie all along at the base of the range. Those here exposed seem to be the upper portion of this zone. It was in those beds that the fossils allied to Inoceramus barabini, (Morton,) before referred to, were’ found, confirming the age of this horizon as being Cretaceous No. 5. Above follows a slope of shalier beds, perhaps 500 feet thick, capped with the bed of sandstones which forms the upper prominent layer seen along the west face of the Williams Mountains. The characters of this sandstone I seem to have failed to record, except that the main massive portion was about 80 feet thick. Above were 500 feet, mostly shaly, with another harder band of thin-bedded, dull-brown sandstone, about 40 feet thick on the summit. In the slope of about 600 feet of softer beds, lying still above, some black argillaceous shale was observed, and at the top harder sandstones, some shaly and dull-brown as before, and some white, inclined to saccharoidal, a few of the harder beds being 18 inches thick. No fossils were observed. Some of the sandstones noticed were whitish and reddish, and rather coarse, while a few only seemed plainly composed of debris of metamorphic or granitic rocks, and to re- semble therein the characteristic coarse lignitic sandstones of the other sections. Indeed, the series seems more to belong to the lignitie hori- zon because lying above the usual thickness and divisions of the Creta- ceous rocks, rather than by the close lithological resemblances so well marked elsewhere in the park. Though differing from the Cretaceous in lithological characters, and having no place in the usual Cretaceous series of the park, they yet retain but to a slight degree the characters of the lignitic rocks farther north. I have considered them the same, however, and have so represented them on the maps and sections. Search would undoubtedly be rewarded with fossils proving their age. From the base of the high terraced front of Ute Peak the long, low, terraced lake-beds sweep out to the Blue, close to the west side of which are the lower indefinite masses of morainal matter from the Blue River Mountains, partially confused with the lake-beds. A few miles to the south the terraces are broken by a broad, uneven rise lying directly across the valley, and through which the river flows in a caton. Ap- proaching it, it is found composed of the Cretaceous beds, the harder marvixe.] GEOLOGY—SOUTHERN END OF WILLIAMS RIVER RANGE. 191 beds forming ridges running across the main valley, and dipping north- ward, with the valleys of softer beds between partially filled with the terraced beds. Meanwhile, on the west, the flat areas at the base of the high mountain-spurs, and which I have considered as covered with Cretaceous No. 1, have approached the Blue, swinging around to a more eastward trend and northward dip, as if to cross the stream ; while on the east the upper escarpments on the face of Ute Peak are eroded away and come to an end, the lower escarpments rising higher, and exposing more of the face of the main ridge, thus showing the background of the meta- morphic rocks which compose it. When first encountered crossing the valley, the northern Cretaceous ridge dips at an angle of 25° or 30° to the north. A little farther on this is followed by a nearly flat dip, and again by a steepening northward one, showing a reflexed or double curvature of the fold. Besides, on the side toward the Ute Peak ridge the sedimentaries, instead of dipping down toward it, seem to have felt more the action of the fault, and dip slightly away from it, so that the valley is now rather a synclinal than a monoclinal, and a synelinal with the axis dipping northward, and its eastern edge cut sharply off by the great fault which has thrust the archean rocks so high up upon the east, and brought them in direct contact with the edges of its slightly upturned lower strata. A little further south, and the edges of the Lower Cretaceous quartzites are found swinging across the valley to their broken contact with the wall of rock upon the east, and the road passes over them on to the granites, which then form the whole floor and sides of the valley, though still for a little distance farther some remnants of the sedimentary rocks lying up against the fault on the east side are visible. From here for a number of miles southward the valley still retains its open though profound character. The southern continuation of the Blue River group still rises most ruggedly and impressively on the west, bordered at its base with great morainal masses; while the lowered spurs of the Ute Peak ridge and adjacent mountains border the valley on the east; the terraced gravels and sands still occupying and concealing the middle portions of the valley. Debris of shales and sandstones was observed at a few points, and may indicate the further presence of some of the Cretaceous rocks. At the junction of Ten-mile Creek from the west and Snake River from the east—the two principal tributaries of the Blue—an area of reddish beds occurs; and again, at the very southern sources of the drainage, and forming a portion of the high mountain divide between it and the South Park, a thick series of sedimentary rocks present themselves which are apparently of pre-Creta- ceousage. Neither sufficient examination was here made either to de- termine their limits or structural relations, nor to ascertrin whether other similar masses might not be present, the region, which is mostly composed of the archzan rocks, and contains important and interesting mines, being left for the coming season’s investigations. It is hoped that in the preceding pages the main purpose of these reports has been accomplished, viz, to present a description, not only of ‘the surface features of the region examined, but also of its interior structure, as to the nature, position, and extent of the rocky masses that compose it, which will be sufficiently clear to be intelligible to the general reader interested in our West. It is further hoped, how- ever, that scattered through its pages may be found some new facts which will ultimately aid in explaining more in detail than heretofore some of the problems of the gradual growth of this portion of the con- tinent, such as the former extent of its lands and waters, and the na- ture of the foldings, dislocations, and erosions which have been mainly 192 GEOLOGICAL SURVEY OF THE TERRITORIES. instrumental in developing the present state of things and in giving us the country as it is now found. Some conclusions touching such points were briefly suggested when the facts upon which they more directly depended were described. By considering together many of the facts thus separately presented, more extended and interesting conclusions may be arrived at, but the facts are confined to too small an area, and are as yet too isolated to afford reliable data for generalization, and as this is not the place to collect facts from other sources and regions, the temptation to draw general conclusions as to the former history of the district is resisted. JUNE 19, 1874. ARCH. R. MARVINE. Boe aN a We ” White-Face Mt. LA Shales ‘NaS Creti eT, ——— == aon S Doleriic Breccia Nad Cretacwaus _ 2 Sane ee . Cretacemts. ~~ Nr = BRON DS eae ~ —B. 25 1. WN. 25E*8.70'W, er y Basaitic Lavras Upper Madly Butte = =I ra (ee ac Lignitic Sandstmes “Cretaceous z pee =a a =— N75 > ES. 75'W. ~—eenerang the p= = =———_—_-s Ligniti No.5 Sandstyne 3.808 —> < VB DEP™’ OF THE INTERIOR. U.S.GEOLOGICAL wp GEOGRAPHICAL SURVEY or tax TERRITORIES F.V.HAYDEN, GeoLocist IN CHARGE. ———— : x : = Plate II. eae = Muy ver GEOLOGICAL SECTIONS °° * SS IN THE MIDDLE PARK To accompany the Report of ARCH. R.MARVINE, MIDDLE PARK DIVISION. 1873. Scale: 1 mile to an inch. Seco. 4, at Hot Springs. Sec 2,3, 4, across Muddy Fir. Valley. Sec. 5,6, across Blue Rir Valley. Jee Hap Pig.S. 3 Park Range ina cc OR C ry Bs re ar A peo Na re einen em he POMITHI. BHT Xp — 2 MOT LAS xe ae arene ARRISA 00H eS ied ye ede Res be Oph. 1 OF eG hea, Wily) NE. GEOLOGIST OF THE SOUTH PARK DIVISION. WASHINGTON, D. C., May 1, 1873. Str: Herewith I hand you my report upon the “South Park District” to which I was assigned as geologist during the season of 1873. To the report of Mr. Henry Gannett, who had charge of the division, I refer for details of organization, routes followed, and the topographi- cal and geographical features. Ihave confined myself somewhat strictly to the enumeration of geological facts, leaving deductions and gener- alizations mainly for the final report to be made when the entire terri- tory shall have been explored. The limited time at our disposal, the want of an accurate topographi- cal map, and the rugged character of a large portion of the region ex- amined were disadvantages under which we necessarily labored, and which will account for any real or apparent deficiencies in the work. In addition to the absolute value of the results recorded, I am satisfied that the data obtained will be of great service to future more detailed investigation. My plan of work was as follows: With Mr. Taggart, my assistant, I instituted a division of labor. One of us did the detailed work at or near camp; the other accompanied the topographical party to the sta- tion of the day, and made a drainage-map of the surrounding country, upon which the geological boundaries were defined in color. This sta- tion was usually the highest point in the region, and the work done from it was of course based upon the details previously obtained. I shall therefore color the final geological map, not from memory nor solely from notes, but from field geological maps. By this plan I am enabled to present a much larger number of detailed sections than I otherwise could have done. I have appended to the report the usual catalogues of rocks and min- erals. In conclusion, I wish to express my obligations to Mr. William hk. Taggart, who acted as my assistant, and by his zeal and efficiency con- tributed largely to the success of our division of the survey. My thanks are due to Mr. William H. Holmes, not only for invaluable illustrations, ‘but also for useful notes on several localities not visited by myself. I desire to thank, also, Messrs. George Summers and M. France, of Colo- rado Springs; Messrs. Stevens and R. A. Kirker, of Fair Play, and C. L. Hill, of Oro City, for favors and information afforded. With great respect, I remain your obedient servant, : A, C. PEALE. Dr. F'. V. HAYDEN, United States Geologist. 13.G 5S 194 GEOLOGICAL SURVEY OF THE TERRITORIES. CE AGP Brel. FROM DENVER TO COLORADO SPRINGS—FRONT RANGH—BERGEN PARK—HAYDEN PARK. On the 29th of May the division of the expedition with which I was connected as geologist left Denver, and proceeded southward to com- mence the summer’s work. On the 1st of June we crossed the northern line of our district a short distance north of the mouth of the cafion of the South Platte River. Here our work commenced. As we look from the plains westward before us rises a plateau-like mass of hills, beyond which we discern the snowy peaks of the main range. I will consider, first, the front range, or the foot-hills, as they are called by the settlers. Seen from a distance, the height of this range seems very uniform. As- cending the hills, however, we find they are much eut up by the various small streams that drain them. The 1ange is made up almost entirely of plutonic rocks, so covered up that little can be definitely determined in regard to them. North of the Platte caion they were thoroughly studied by Mr. Marvine, and to his report I refer the reader. On the south the general strike seems to be nearly north and south. The ineli- nation at some points seems to be toward the west, and at others to the east. There is probably a series of folds, for the elucidation of which more time than we were able to give will be required. Toward the out- side of the range the schists are of a bright-red color, from the predom- inance of the crystals of flesh-colored feldspar. They are also porphyr- itic. As we approach the center of the plateau, gray schists prevail, much finer grained, and containing considerable epidote : they are also more micaceous. ‘The general elevation of the range, two miles south of the Platte River, is 6,735* feet. Five miles farther, at Station No. 7, it is 7,979 feet. About nine miles south of this station we have, on the western side of the range, rising considerably above it, a rough granite ridge, to which the name Platte Mountain has been given. Its elevation above sea-level is 9,027 feet. About five miles below it the general ele- vation is 8,448 feet, while on the eastern edge of the range, twelve miles south of Platte Mountain, the elevation at Station No. 11 is 8,986 feet, - and this, five miles farther south, at Station No. 12, increases to 9,124 feet. We see, therefore, that as we go south there is a gradual rise toward Pike’s Peak, which seems to be the culminating point. The width of the range varies somewhat, but it will average from six to eight miles. The question of the elevation of the range, as well'as the con- sideration of its. western slope, I will leave to a subsequent portion of the chapter. I will refer next to the sedimentary formations, which are beautifully exposed along the eastern edge of the range, extending from our northern to our southern line, south of Pike’s Peak. My first sec- tion was made on the south side of the South Platte River, just as it leaves the canon, and flows toward the plains. Its course here is about north 70° east. Resting immediately upon the granite rocks we have very coarse sandstones, mottled red and white. Close to the granite the sandstone is coarsest, and contains pieces of unchanged granite. In other places the sandstone appears to pass by gradation into the granite. They were * All the elevations in this report are based on the elevation of Denver, which is assumed at 5,069 feet above sea-level. ‘YOIMD MOTI Ssuoze wdoyoay RWW ZAR S RANG . Sneens xX Wy \ ) \ H x » "I TF [a | SX LUE ESO ME CUE Np WOO NG Rone CWUVECOEEE IER RUAN Miniee : \ * DOV GLI: SASS == ‘T 931d y ee GEOLOGY—SECTION NO. 1. 195 evidently deposited in shallow water and near a shore-line. The angle of inclination is about 65°, and the dip is north 65° east. Above, the sandstones soon become uniformly red in color and some- what finer grained. Fig. 1, Plate I shows the beds on the north side of the river, their relations being exactly the same as on the south side, where the section was made. The following is the section : Section No. 1, on south side of South Platte River. In descending order: 4; f 1 Fine-grained white limestone, with cross fracture | 2. Gray limestone, (fossiliferous).......:..-...-. cet Cretaceous No. 2,*h. 3. Space covered up. . Gray and yellow sandstones, 70 feet..-. ) . Shaly sandstones, (fossiliferous,) 12 feet. | . Fine-grained white sandstone, 3 feet .... } ....... .. -930 feet. . Rusty, yellow sandstones, 245 feet ...... | . Space covered up, estimated 600.feet .... | White arenaceous limestone, 5 feet....-... ») . Pink caleareous limestone shales LB on || . Arenaceous and pebbly limestone b (POPACCGVELeM UP = cic = 20 | . Compact red limestone........ BOD fee \ White sandstone with red bands.........-. ....-... 600 feet. SPACE TCOVELCUMED ec ot seu. ita. 2 . . Red sandstones......... So eet ON era ee galt fee He 2,000 . Coarse white and red mottled sandstones. ee . 18. Granite. The thicknesses in this section are for the most part estimated. The letters correspond with those in Fig. 1. Beds 14 to 17 will still have to be considered as Triassic (?) both from their general character and their position. Although there are exposures of these red sandstones all along the edge of the foot-hills from Denver southward, I could find in them no fossils, even after the most careful search. They are for the most part so coarse in their texture as to be unfavorable for the preser- vation of animal remains. The space No. 15 in the section is, in all probability, filled with red sandstone, of which No. 16 is the continua- tion. In No. 14, the white portions are somewhat conglomeritic, while the red bands are fine grained and calcareous. The red bands vary in thickness from 4 feet to 6 feet, while the others are 20 feet to 30 teet at this place. As we go south, however, we find that these sandstones are very irregular in structure. No. 13 is a blood-red limestone, somewhat irreg- ular in structure, but very hard. Although it contains no fossils, I am inclined to consider it, together with beds 9, 10, and 11, as of Jurassic age. Space No. 12 is filled most likely with limestones, while in space No. 8 we have at the top greenish shales passing down into limestones with the gypsum bed, as seen in some of the sections made farther south. The pink calcareous shales (No. 10) pass gradually into the limestones (No. 11) in which there are large flinty pebbles. All the beds covered up in space 8 are probably Jurassic. That these beds from No. 8 down to No. 13, inclusive, should be referred to that age, is, J think, scarcely to be doubted, not only from their position, but also * The letters given in the sections refer to tne illustrations. No. 1. f. Suras- g.Cretaceous sic. EU ae 150 feet. . . NASP OD RSS WAH OUP Triassic. SS RHE Re b,c, and d. *eand 3 196 GEOLOGICAL SURVEY OF THE TERRITORIES. from the lithological identity with beds that are undoubtedly Jurassic in the following section made by Dr. Hayden at Box Elder, in 1869. The following is the section made by him in ascending order :* 1. Brick red sandstone, with irregular lamine, and all the usual signs of currents or shallow water. Some of the layers loosely laminated, causing projections, Thickness, 300 feet to 400 feet. Yellow or reddish yellow massive sandstone, 60 feet. Grayish yellow, rather massive sandstone, 50 feet. Ashen brown nodular, or indurated clay, with deep, dull purple bands; with some lay ers of brown and yellow fine-grained sandstone, undoubtedly the usual Jurassic beds, with all the lithological characters as seen near Lake Como, on the Union Pacifie R allroad. Near the base of these beds are thin layers of a fine-grained grayish calcareous sandstone, with a species of Ostrea and fragments of Pentacrinus astericus. Scattered through this bed are layers or nodules of impure limestone, 150 feet to 200 feet. Oo. Sandstone and laminated arenaceous material varying in color from dirty brown to’grayish white, with layers of fine grayish- white sand- stone, 200 feet. Dr. Hayden says, ‘I do not hesitate to regard the beds described as 4 and 5 as of Jurassic age, and they are better shown here than at any other point between Fort Laramie and the south line of Colorado, on the eastern slope of the Rocky Mountains.” Nos. 1, 2, and 3 of this section correspond to Nos. 16 to 14 of the South Platte section, (No. 1.) Beds Nos. 4, 5, 6, and 7 of section No. 1 form the main hog-back which iS SO conspicuous along the entire extent of the foot-hills. No. 4 forms the summit of the hog-back, and is a rather fine-grained uniform textured siliceous sandstone. All these beds belong to the Dakota group No. 1 Cretaceous. Layer No. d contains a large percentage of carbonaceous material, and in it I found fragments of leaves and stems. Among the former, Professor Lesquereux has recognized a Proteoides very near Proteoides acuta, (Heer.) These shaly sandstones weather of a bluish color in places, and are followed by No. 6, which passes into No. 7. The latter has occasional shaly bands, and in some places instead of being yellow the sandstone becomes reddish. Space No.3 is filled in with No. 2 Cretaceous, Fort Benton group, and perhaps a portion of No. 3 Niobrara division, to which formation also I refer the layers marked Nos. 1 and 2. No. 2 is somewhat sandy, and in places is very dark colored, and on being fractured has a perceptible bituminous odor. It contains quantities of Ostrea and a few Inocerami. Hast of these beds the country is so leveled that the remainder of the Cretaceous forma- tion aud the entire extent of the Tertiary beds are concealed, being covered by the local drift from the hills. That the Tertiary layers are not far distant, however, is evident, for along the Platte River are ex- posures of lignitic sandstones. After passing out through the main hog-back, (Cretaceous No. 1,) the Platte turns to the northward, and its course is about north 7° east. The dip of the main hog-back at the Platte River is north 65° east; angle 55° to 60°. Fig. 2, Plate I, repre- sents a section made at Willow Creek, five miles south of the Platte. The dip here is north 55° east; angle of inclination, 50° at the outside, increasing to 55° as we go down to the red-beds. It is not necessary to give the beds of the section here, as it would be a repetition of the order given in the Platte section, (No. 1.) They are so much alike that I will refer only to those where there has been some change. The thicknesses are about the same. In No. 14 of the Platte section, at this place, we have * Report for 1869, page 19. ee GEOLOGY—SECTION NO. 2. OC merely indications of the red bands, the prevailing color of the sandstone being a creamy yellow. The lower beds are perhaps deeper in color and not so much mottledas at the point wheresection No. 1 was made. Iwas unable to carry the section any farther to the eastward. . Willow Creek after leaving the hog-backs turns and Hows nearly northward, emptying into the South Platte River five miles below the cafion. As we go south from Willow Creek, the upturned edges of the sedimentary beds are covered up, and between Jackson and Spring Creeks we find resting on them sandstones of Tertiary age, which reach to the edge of the hills. These sandstones contain fossil leaves in which Professor Les- quereux has recognized Platanus nobilis and a Sabal. The beds are prob- ably lignitic. On Jackson Creek are some well- defined terraces sloping from the mountains. On Spring Creek the sedimentary ridges again show themselves, and on Bear Creek we have them beautifully exposed in Pleasant Park. This beautiful little park is studded with pines. Its western boundary is the range of foot-hills, while on the east the main hog-back (Cretaceous No. 1) separatesit from the valley of West Plum Creek. Bear Creek flows through the park, cutting across the ridges at right angles to the strike. Inside the sandstone wall we have ridges of sandstone and limestone, giving the park some most picturesque scenery. Just before reaching the park, Bear Creek flows in a series of eascades through a deep and narrow cafion in the foot-hills. Plate II shows the outline of a section through Pleasant Park eastward across West Plum Creek Valley to one of the mesas between the two branches of Plum Creek. The following is the section: PEALE.] Section No. 2, through Pleasant Park. In ascending order: a.— 1. Granite. { { 2. Very coarse white can iieions, 80 feet. | 3. Red calcareous sandstone, 4 feet. ale 4. Dark purplish cherty limestone, 3 feet. = | 5. Compact red sandstone in layers of one foot thickness, with B cross seams of calcite, 15 feet. 5 | | 6. Red calcareous sandstone, very hard, and with cross cleav- Zs 0.4 age layers of one inch, 3 feet. BI | 7. Irregular limestone, with pebbles of greenish chert and lime- a) . stone, 3 feet. 2 8. Indistinct outcrop of limestone with chert pebbles and fos- siliferous: in the upper part of the space we have a purplish sandstone, above which is a gray sandstone passing into the next bed, 6 feet. ) ( ¢e.— 9. Coarse white sandstone loosely aggregated. In the upper S part of these beds there are bands of red sandstone vary- z ing in thickness from one to three feet, 80 feet. = LO Spaeelcowered, Wp-u)..\--). be. ee ~ . a | d. \ 11. Massive red sandstones ....-..... Ma oe cephiay ! e.—12. Mottled yellow and red sandstones. : = RLS RMALS 22-22 2\<1- ii VY annegas Sy abate a, ] 14. Pink arenaceous limestone, 4 feet. . | 7m vRNA We = 5) ooo oe pli eve tla (dl apes hee fs ! 16. White limestone, 3 feet........... | ey | ee Lee SACO AS TOOL. i. wie cence sscne nese . Fine sandy limestone shales, 4 feet. Jurassic. (?) . White limestone, 2 feet . Space . Gypsum, 81 feet . White sandstone, 22 feet | . White limestone, 2 feet....-.....- | PSpacemlOO Meet oo 6) cid ie ee Rena i . Massive siliceous sandstones, yellowish, 213 feet. . Space. . Limestones, fossiliferous. . Space, valley of West Plum Creek. . Brown sandstone shales, 2 feet. . Space. . Yellow sandstone shale, . Kine white sandstone, 6 feet. GEOLOGICAL SURVEY OF THE TERRITORIES. Sas . Pink mottled laminated shales, 9 \ About 461 feet thick. feet eeensetetecres eee eee ees eee ee weer eer see we aoocree ce @® eee wee cee. eH Aer sew woe eee eee ee ee pe we ccc ee ese er 2 feet. Yellow sandstone, 10 feet. Space. . Yellow sandstone, 60 feet. Space. . Yellow sandstone, 75 feet. . Space. . Sandstone conglomerates, $41 feet. p.—4l. Trachyte, 20 to 30 feet. In this section I am inclined to consider all the beds from No. 2up to the base of No. 9 as Carboniferous, a total thickness of about 114 feet. None of these lower beds seem to agree with the Silurian layers in Glen Hyrie, nor with those found west of the range on Trout Creek. I have therefore referred them all to the Carboniferous. Future investigation may modify this view. The fossils found in No. 8 (Terebratula and Spiriferina,) prove it to be Carboniferous beyond doubt. Layer No.9 is the same as No. 17 in the Platte River SeSEIOD, (No. 1,) and is the lower portion of the Triassic. Nos. 9, 10,11, and 12 , comprehend the beds that we have in Nos. 14, 15, 16, and 17 of the Platte section, (No.1.) Here, however, they do not appear to be so thick. The difference may be ap- parent rather than real, as the thicknesses in both cases are only esti- mated. The red sandstones (No. 11) are massive, and present the same characters we have seen in the same beds all the way from the Platte southward. Space No. 10 is probably filled with an extension of these beds into those of No. 9. The red sandstones in the upper part of No. 9 are of a dark purplish color. The angle of dip of the lower beds (No. 2 to 9 inclusive) is 10°; at No. 12 the dip has increased to 309. The red sandstones are not abruptly succeeded by the yellow sandstones of No. 12, but there is a gradual change, the upper part of No. 11 being somewhat faded, while in the lower part of No. 12 we find streaks and spots of red. These variations in color give the bluff on which they are exposed a rich and beautiful appearance. In the upper part the sandstones of No. 12 become very light colored. Space 13, as indicated by several indefinite outcrops, must be filled with the continuation of the sandstones of No. 12. The dip on the summit of the ridge is north 65° east. In No. 14 we have the lowest of the beds that I have con- sidered as Jurassic, extending up to space 25. Near the top of No. 19 is a layer having a veryirregular structure, and containing cavities lined with crystals of calcite. The lamination is most decided at the bottom. The gypsum bed (No. 22) is well exposed here. As we have it again ‘YIU JULSLOTY IvOU MOT}IeG Z eqeId Pi ete gS ert } , Ne ne Ce tag en ag mt rt Ot eh Sages peare GEOLOGY—SECTION NO. 2. 199 near Colorado City, it probably continues southward uninterruptedly. Tt can be traced northward as far as Spring Creek, but above that point seems to be covered. Whether or not it is present at the the Platte River I could not determine, as the space where it would be found was covered so that all the beds were totally concealed. The space (No. 21) below the gypsum is probably filled with shales and lime- stones. That above is filled with the shales just below No. 1 Cretaceous, which is represented in No. 26. The general color of these sandstones is a yellowish white, becoming pink below. No. 27 is filled, in all prob- ability, by the sandy shales of Cretaceous No. 3. Everything is con- cealed until we reach 28, where we find the same fossiliferous limestone that we have in bed 2 of the Platte section, and outside of it the out- crop of the white, chalky-looking limestone with cross fracture. From this outcrop, which forms a low ridge outside of the hog-backs, we have no exposures until after we have crossed West Plum Creek, a distance of about three-quarters of a mile. This would give us, with the dip at 10°, a thickness of about 700 feet of strata, mostly the shales of No. 4 and the upper part of No.3, to which No. 28 of the section is referred and of which it forms the lower part. Beds 30 to 38, inclusive, I have referred to No. 5 Cretaceous, although I could find no fossils to prove the correctness of the opinion. Their position and lithological charac- ter warrant their being so considered. The dip of these beds is about 20°. The junction between them and the horizontal sandstones in the butte shown in the section could not be seen, as the base of the butte is covered with debris. At the base of the butte is a thickness of about 840 feet of rather coarse sandstones. Some of the layers are rusty- colored, and they are nearly, if not quite, horizontal. They are capped with a layer of light purplish trachyte. This capping is about 20 feet in thickness. The area of this mesa or table-like butte is about 30 acres. AS we approach the Colorado divide, the Tertiary sandstones reach to the mountains, resting on the upturned edges of the older formations. Plum Creek and its branches have cut their valleys through these sandstones and conglomerates. Throughout the valley _ of Plum Creek we find numerous mesas, and all that I Visited were capped with trachyte. The origin of this voleanic material I was unable to determine. These sandstones probably belong to the Mon- ument Creek group, and once extended to the edge of the mount- ains along the whole range as we still see them on the divide. The summits of the mesas show us the original surface before the eroding agents had commenced their work. The Colorado divide, or Pinery, is a ridge with a mesa-like top extending eastward from the mountains. It is merely the undisturbed sandstones of the Monument Creek group, capped with the trachyte layer, and forms the water-divide between the branches of Monument Creek, which flow southward to the Arkansas Riiver, and the waters of Plum Creek, which empty to the northward in the South Platte River. The divide is well timbered, and is already the seat of an extensive lumber trade. The shrill whistle of the steam saw- mill echoes and re-echoes among the hills, while the valleys are all being rapidly settled and the capabilities of the land for agricultural pursuits being demonstrated. On the divide close to the mountains, the eroding forces have cut a narrow pass in the Monument Creek group, and the fragments of these sandstones are seen resting immediately on the granites, while to the eastward the beds continue uninterruptedly. This pass is about half a mile in width, and through it the Denver and Rio Grande Railroad crosses on its way southward. In the sandy débris 200 GEOLOGICAL SURVEY OF THE TERRITORIES. on the divide, and on either side, very good crystals of smoky quartz are found. Crossing the divide, we find ourselves on the branches of Monument Creek. On this side, the overlying sandstones have been subjected to less erosure than on the north side, and with the ex- ception of a few indistinct outcrops of the red-beds a short distance south of the divide, the underlying formations are concealed until we get within a few miles of Colorado City. Between the branches of Mon- - ument Creek on the western side we have sloping from the mountains eastward long grassy terraces. Monument Creek flows in a southerly direction, and the general slope of the country from the divide is south- ward. As we go down the creek the sandstones of the Monument Creek group rise like long lines of fortifications and castle-walls on the eastern side. On the western side also we have remnants left. There are, just south of Beaver Creek, several monument-like forms that are perfectly isolated. Theterraces here are about 96 feet above the level of the creek. This height is near the mouth of Deadman’s Creek, the first creek south of Beaver Creek. As we go toward the mountain, of course the eleva- tion increases. Thus at the point given above the elevation is 6,592 feet above sea-level. On West Monument Creek, three miles farther south, and about two and a half miles west of the previous station, the elevation is 7,014 feet. In Monument Park we find the sandstones curiously eroded, so that there are monuments and pillars scattered throughout its extent, from which fact it derives its name. The follow- ing description is mainly from the notes of Mr. Taggart: The park lies south of West Monument Creek, and is an elliptical basin, about two miles in length from east to west, and three-quarters of a mile in width north and south. It extends from Monument Creek westward, where it is bounded by the ridge of sandstone (Cretaceous No. 1) which forms the main hog-back. The columns and monuments are found in two ridges that run lengthwise through the park. These monuments are from 12 to 25 feet in height, and are composed of sandstones of the Monument Creek group. The lower third of the exposed rock is fine- grained, containing argillaceous layers, and also carbonaceous shales. Above, theesandstone is very coarse, becoming almost conglomeritic. It — is from the breaking down of these layers that the local drift, found along the edge of mountains, is derived. The capping of the monu- ments is a dark ferruginous sandstone conglomerate, very hard, the sand and pebbles being cemented by iron. This layeris about 12 inches thick, and being so much harder than the underlying sandstone, has been more successful in withstanding the eroding influences, and in some places we see it extending continuously over a number of the columns. West of Monument Park, and forming its boundary in that direction, we find the massive sandstone of No. 1 dipping under the Monument Creek group. From this point southward to a point below Colorado City we have this sandstone and the underlying strata well shown. The west section, perhaps, is shown in Glen Eyrie, a beautiful little caion, which Camp Creek has cut through the granite and superimposed strata at the ‘‘ Little Garden of the Gods,” about two miles above Colorado: City. In the cation the creek flows in an almost easterly direction. After getting outside of the hog-back it turns abruptly and flows due south along the strike of the upturned-shales and sandstones. The following section is made from Glen Eyrie, eastward, to Camp Creek, and is in ascending order corresponding with Fig. 2, Plate HI. Plate 3. cia NSS Epil Ih @ “Coloraca. Breringe Jéiew shoning tum in Beds below the Garden of the Gods & Steyonne Mouncatra C Nol Cretaceous A. Sepang Ene hatreen Grantta anct Stclinrentary Beis it | 0 iH dp, AY, Ue Mae his Be oi ii Pak Sections from Glen pe EL ane 7 re . KK a a LEE pie a ce \\ it \ ? 7 ri a ae Age SA THY (A wt woe a a TR AIT i # van Wo me) NTRS ne mh eet nds hd = es Sat mie ai =-5 a 2 he hearers 4 Pes Sra Sr Sh : 4 R ‘i elie = “ti PEALE. | > ns CU 09 hD t Featreeta ree SIDE OOMNAIG 4 (as) Silurian and Carboniferous (2) k, l, m, and n fae Tt He be OS se eo Triassic. S 19. Jurassic. é. 29. Cretaceous. poe eee eB OO OhbHos s ( 44, co“) S a a. b. Jurassic. . Bluish calcareous and argillaceous shales. - . . White shaly limestone, (fossiliferous)........ . Dark-gray limestone, (fossiliferous).......--- 4 Aidereetn E wubite shialy, limestone ot: ee 6 3 pyslepelsrenvs'e yoy GEOLOGY—SECTION NO. 3. 201 Section No. 3. . Granite. . Coarse grayish white sandstone, 20 feet. > . Coarse dark-green sandstone, 4 feet.... . Coarse gray sandstone, 6 feet.....-.--. Le es 40- feet. Brick-red sandstone, with green layers, NS Nae . Red and greenish limestone, 5 feet... .-. 7 . Irregularly laminated limestone, 3 feet. - | Bee COIMeESHORG. WLOO bse) 5 selene ac Sete ap ee er ee 19) feet. . Red shaly limestone, 1 foot... .--.....-.- | pCO WIMESTONE yee (orueian oy Salsa nia | . Red limestone, with flint nodules, 7 feet. . Limestone, with interlaminated shales, 7 feet. ted shaly limestones, with fragments of fossils, (Silur.,) 4 feet. . Gray purplish and yellow limestones, 279 feet. WETS) TANCE! SOT Pan aos AMR aM ha Efe ELC nea . Masssive red sandstones.....-....-.---- ; about COUIEet . Space of 200 feet. . White sandstone, becoming pink below 60 feet. Calcareous shales, dark and light red, with green layers, 20 feet. . Pink-moitled shales, 1 foot. . Light-red sandstone, 2 feet. ged. Calearegus Shales cco 8 ecu alten } = . Green calcareous shales......-.. ae eer oe . Brick-red shales, 6 inches. . Compact sandstone, 3 inches. . Fine-red calcareous shales, 6 inches. . Sandstone shale, 6 inches. . Gray arenaceous limestone, 5 feet. ..7 Inches. Space, 57 feet. . Gypsum bed, 57 feet. . Soft gray sandstone, 3 feet. . Compact limestone, 2 feet. . Pebbly limestone, 2 feet. . Compact gray limestone, 18 inches. . Hard calcareous clay shales, 4 feet. . Space, 49 feet. . White massive sandstone, 200 feet. . White fine-grained sandstone, becoming yellow } as we go down; again white near the bot- | tom, we have a layer that is lignitic, contain- | ing fragments of stemsand leaves. This is }...57 feet. just below the yellow layer in which I found fragments of shells (Lingula) that were very AURCLUSEUINEL cate ho) HIS clam, pegs oroie ate] she Slelecere 5 Space, 150 feet. ..-00 feet. White limestone, with cross fracture.......-- This section extends over about three-quarters of a mile. Beds No. 2 to No. 14, inclusive, have a dip of only 10°, and are alk 202 GEOLOGICAL SURVEY OF THE TERRITORIES. older than Triassic. From No. 13 down allis Silurian. Perhaps the limestones of No. 14 should be referred to a higher horizon. Beds Nos. 2 to 5 I have referred to the Potsdam group, while those just above are undoubtedly of the Quebec group, as in beds lithologically the same in the western side of the range I found characteristic fossils. I found in them Terebratula and Crania. In these beds, also in the Ute Pass, in 1869, Dr. Hayden found Ophileta complanata, Bucanella nana, (Meek,) and other species, from which Professor Meek referred the beds to the Calciferous division of the Lower Silurian.* ‘The line of junction be- tween No. 14 and No. 16 could not be seen, as it was covered with débris. | The massive red sandstones of No. 16 (No. 16 of section No. 1, and No. 1 of section No. 3) are here tipped 5° past the vertical, and the weath- ering of these ridges has given rise to the peculiar forms seen in the ‘‘ Garden of the Gods,” and which have been fully described in previous reports. These sandstones have here the same general characters that we have noticed all along the range. They are still coarse-grained, giving evidence of their deposition in shallow waters. I was unable to get the thickness of the beds, but estimated it, including No. 18 and the space between, at about 1,000 feet. From No. 19 up to the bottom of No. 37, we have the layers that I have considered as Jurassic. Inthe gypsum bed (No. 30) I found some selenite and some fair pieces of satin spar. Nos. 37 and 38 represent the No. 1 Cretaceous, while the space just above, (No. 39,) which is in all probability filled with shales, be- longs to the Fort Benton group. Bed No. 40 is filled with excellent specimens of Inoceramus, while in No. 43 we have quantities of Ostrea. This bed has the same bituminous odor on breaking that I noticed at points farther north. The dip of these beds is about due east, at an angle of 30°. This angle as we go down increases quite rapidly. At No. 40 it is 55°; at No. 38 it is 60°, and at No. 39, 65° to 70°; below this it decreases to 50°, and at No. 18 the beds are vertical, while the red-beds (No. 16) are tipped past the vertical, as we have already seen. Between Camp Creek and Monument Creek, a distance of about two miles and a half, there is a drift-covered mesa, in which the beds are entirely concealed. They belong probably for the most part to No. 4 Cretaceous, and perhaps the upper portion of No. 3. In the banks of Monument Creek we find the upper portion of the black shales of No. 4. In the bed of the creek, a few miles above Colorado City, we find a bed of hard, bluish limestone, which is in thin layers, and contains Inocera- mus and other cretaceous fossils. Above this there are brownish and black shales, all more or less fossiliferous. Above the black shales we have a thin layer of sandstone, containing Baculites and Ammonites. Above this are sandstones. Above the cretaceous layers are the lig- nitic beds. These have been studied by Professor Lesquereux, and I refer to his reportt for the details. I will only insert here a section made by him at Gehrung’s coal-mine: 1. Brown laminated fire-clay or chocolate-colored soft shale, a compound of remains of rootlets and leaves and branches Oindeterminable, comers es es see ee ee ia ee 2 feet. 2. Coal, soft, disaggregating under atmospheric influence... 2 feet. 3. Chocolate-colored clay-shale, like No. 1, with a still greater ; proportion of veretable, devs). - 225-65 se ee ere G6 feet. 4. Soft yellowish coarse: sandstone in bank................ 8 feet. 5. Clay, shale, and shaly sandstone covered slope.........- 150 feet. *Report 1870, United States Geological Survey, page 287. tReport 1872, page 325. * pean] 4 GEOLOGY—SECTION AT GEHRUNG’S COAL-MINE. 203 6. Soft laminated clay, interlaid by bands of limonite iron ore, thin lignite seams, and fossil-wood................ 88 feet. Penance black clay, im banka 2s! oo .04 ces ye ve oe eos Me 32 feet. Pephine-crained Conglomerate .6. ssc 0c. see ce Loe oe 112 feet. Semime-craimed sandstoneys... 44. hace eee ose Sone ee we. 4 feet. Beet Ser Cone OMerate .. Acct eye aeree GR). Laie eats wos ¢ 7 feet. MEATUS HOU Geek pte as at Ee iee hap nett ed co) ure ees «ated b 3 feet. Peer errucinous hard conglomerate in. 2s se. sys Hsien eee. 32 feet 426 feet. The coal found here is of poor quality, and at present I believe the mine is not worked. Professor Lesquereux found the following leaves in the sandstone, No. 4 of the section: Sabal leaves, Platanus Haydenii, Newb., Dombeyopsis obtusa, Lesq., and Ficus tiliefolia, A. Br. Through the kindness of Mr. France, of Colorado Springs, I was taken to an out- erep of coal twelve miles east of Colorado Springs. We could see only the top of the coal-bed, which was exposed in the dry bed of a creek. [ was told that the bed was 9 feet in thickness. All the coal I saw was of very poor quality, having been exposed for some time to the weather. Just above the coal, there is g bed of chocolate-colored clay shale filled with fragments of leaves and stems. This bed is about 2 or 3 feet in thickness, and above it isa very soit yellow sandstone, in which I found * impressions of leaves, among which Professor Lesquereux has recog- nized Khamnus Cleburni, Lesq., Sabal leaves, Ficus spectabilis, Lesq., a Pali Urus, and a Quercus. These plants characterize the layers as be- longing to the lignitic group, as do also the beds at Gehrung’s, to which they so closely correspond. ‘The clay shale on top of the coal is precisely like the clay of No. 3, in the section made by Professor Les- quereux, while the yellow sandstone in which [ found the fossils is evidently the same as No. 4. A short distance west of this outcrop, there are massive beds of white sandstones and conglomerates corre- sponding to the sandstones and conglomerates given in the section above the coal. These are the beds that, seen from Colorado Springs looking northward, appear like huge castle-walls. Even out on the plains they stand up in bluifs. Just west of them, at the latter place, I visited an opening that had been made in hopes (not realized) of finding coal. The shaft had been carried a distance of about 50 feet into a lignitic clay, corresponding, I think, to beds 6 and 7 of the Gehrung section. All these beds out in the plains are nearly horizon- tal, dipping perhaps 5° to the northward. Returning again to the upturned sedimentary formations near the mountains, both the dip and strike vary considerably. Thus, in the Cre- taceous layers on Camp Creek, it is 30° at the point where section No. 5 was made. This dip was taken on bed 44 of section No. 3. It repre- sents a portion of. the Fort Benton group. Following this to the south- ward, we find the dip increases rapidly. On the high ridge of Creta- ceous No. 1, beds 37 and 38 of section 3, near Glen Hyrie, it is 65° to 70°, Going south, and crossing the “ Fontaine qui boulé,” the beds incline past the vertical; and still farther south, on Bear Creek, they are vertical. The dip then decreases after crossing Bear Creek. As we go westward, however, to the older formations, the angle of inclination is very much smaller. Thusin Glen Eyrie it is only 10°, while in the Ute Pass the older sandstones rest upon the granites, inclining at vari- ous angles, but never exceeding 20°. Returning again to the hog-back, we observe in Fig. 1, Plate III., that the strike also Varies. Opposite 204 GEOLOGICAL SURVEY OF THE TERRITORIES. Glen Kyrie it is north and south. This turns slightiy to the eastward, until we reach the “Fontaine qui boulé,” when there is rather an abrupt turn to the west. Between the “ Fontaine” and Bear Creek the strike is N. 40° east to S. 40° west. Where the strata cross the creek is still another turn to the eastward, and the strike here is north 25° east. On the south side of the creek is a more abrupt turn, and the strike is south 15° east. Krom this point southward the beds are entirely con- cealed, and do not appear again until we get south of Cheyenne Mount- ain, where they are in Dr. Endlich’s district, and will be considered in his report. 3 In section No. 3, we have seen that the lower beds (Silurian) dip at an angle of only 10°, while the red-beds (Triassic?) just above are tipped 5° degrees past the vertical, and that the inclination of the succeeding layers becomes less and less as we go eastward, until on Monument Creek it is only 5°. This variation, especially the abrupt change from the Silurian to the Triassic, can, I think, be best explained as follows: After the deposition of the Silurian, and possibly the Car- boniferous beds, there was an elevation of the range north of Pike’s Peak, the peak itself being the center of elevation. Succeeding this, we have the period during which the red sandstones were deposited. These beds near the Silurian shore had a slight inclination, perhaps only a fraction of a degree. Then, after the deposition of the red sandstones and the succeeding layers, there was a second elevation of comparatively modern date, which tipped up the sedimentary formations as we now find them along the entire range. This force at the foot of Pike’s Peak eaused the slightly-inclined red-beds to be tipped past the vertical. The following explanation also is possible: It may be that the difference in the angle of inclination is due simply to a fold, and that the red sand- stones that we ought to find resting on No. 14 of section No. 3 have from their softness been entirely removed, leaving only the vertical portions. If this be so, we should expect to discover beneath the surface that the lower limestones conform to the Triassic beds, (No. 16, section 3.) The case then would be analagous to that near Golden, which is described in Mr. Marvine’s repor6. At the foot of Pike’s Peak, around the northeast side, during the Silurian age, a bay probably extended in to the westward. That it ever extended across to the west side is exceedingly improbable. The beds extend farther up on the hills here than at any other point north of the peak. At the South Platte River, in section No. 1, the Triassic (?) sandstones rest immediately upon the granite, and it is not until we get some distance south that we have any older beds exposed. At Pleas- ant Park we have Carboniferous beds beneath the Triassic layers, but it isnot until we get to Glen Hyrie that undoubted Silurian shows itself. That both the Silurian and Carboniferous layers are beneath the red- beds (Triassic?) along the entire range is scarcely to be doubted. Their non-appearance to the northward can be readily explained. The force that elevated the range radiating from the center at Pike’s Peak, and very likely also from Mount Evans to the northeast from the first point and eastward from the second, caused a general elevation of the plains to the northeast and east. This elevation would enlarge the ancient sea-border, and cause the succeeding deposits to overlap the older ones, and therefore rest immediately on the granite. The same effect might of course have been produced by a general de- pression of the country. In this case, however, I think it is improbable that depression has been the cause. All the facts seem to point toward an elevation. The overlapping diminishes as we go southward. The . Sanaa a 7, A MED TET UB LLL Wie LLY EY LY DUM YL UNL Ly) LLL ULL GULL YUL pi) “UU DF MI YY MY WUY[gapy), yp YU 22 Ty 11/7 yy oe 7 = yy YW = Grantte Plate 4. 2 Pleasant Park Mie EET serosa Vesey, a YY es y, yy j yy WY) Yj 7 Vy LL we Zo YY) LLL EM o Wy Ae Yee Ly UUM, ey UMMA LLM HU MM TMU WY Sections giving comparative thickness of sedimentary strata. ere vale cab Ae Sa Ras teat besten ‘oie WROD “a? PEALE.] GEOLOGY—PIKE’S PEAK. 205 difference in dip between the Silurian and the Triassic in section No. 4, also points to an elevation rather than depression. Near Pike’s Peak the force was direct enough to elevate the Silurian layers above the sea, and cause them to- form part of the shore-line, while the border of the sea retreated to the eastward. To the north and northeast, however, the force was more widely distributed, the elevation more general, and we have the margin of the sea more to the westward. The widening of the.sea-borders would, of course, result in a shallower sea, and the char- acter of the red sandstones points to a comparatively shallow sea during their formation, while their structure shows them to have been derived in all probability from the red porphyritic granite found along the margin of the foot-hills from Denver southward. Pike’s Peak is composed of a very fine-grained reddish granite. Itis a question whether the rock is eruptive or metamorphic; I incline, how- ever, to the opinion that itis metamorphic. About the base of the peak I found, rather abundantly, good crystals of amazon stone (green feld- spar) and smoky quartz. It is doubtful whether the sedimentary beds ever extended across the range of foot-hills from the east to the west side. There is no positive evidence anywhere along the range that they did. No remnants are to. be found on the plateau, and it is scarcely probable that the beds would have continued uninterruptedly across without having left some trace. The nearest approach is near the foot of Pike’s Peak, where the older formations extend for some distance up on the hills near the Ute Pass; but this, as I have before said, is due to the existence here, during Silurian times, of a bay extending to. the westward. I do not think it reached to the head of West Creek, although, as we will see further on, the Silu- rian beds on Trout Creek are exactly like those in Glen Hyrie. Taking a general view of the sedimentary formations along the eastern flank of the mountains, we see that the red sandstones have their greatest devel- opment near the exit of the South Platte from the mountains, and that as we go southward they become much thinner. This is shown by the sections in Plate LV. In No.1, the section at the Platte, the red-beds have an approximate thickness of 2,000 feet, which at Pleasant Park, No. 2 in the plate, has decreased to 1,280 feet. At Camp Creek, sec- tion No. 3 in the diagram, I was unable to ascertain the exact thickness, as the line of junction between the red-beds and those next below was very obscure. I have, however, estimated the thickness at 1,000 feet. With the exception of No. 1 Cretaceous, the other beds also decrease to the southward, as seen in the diagram. Considering the strike, we find that north of the divide, or Pinery as itis sometimes called, itis very uniform. Thus, at the Platte, it is north 25° west; at Willow Oreek, north 35° west; and at Pleasant Park, north 30° west. Below the divide is a turn to the westward, and east of Glen Eyrie the strike is north and south. From this point, as we Bec already seen, the strike changes. I have already treated of the ips. The Garden of the Gods, the springs, and the various beautiful callous about the foot of Pike’s Peak have been so fully described in previous reports that I will but refer to them here. It is to their attraction, per- haps, that Colorado Springs and the village of Manitou owe their pros- perity. Within a year the former town has more than doubled, both in Size and population. At Manitou is a large hotel for the accommodation of the visitors that every summer resort to the springs. There are also many beautiful cottages about the springs, and the springs themselves are inclosed in tasteful pavilions. 206 GEOLOGICAL SURVEY OF THE TERRITORIES. It will be necessary here to give only this year’s observations, and for details the reader is referred to the reports of 1869 and 1872. The water from one of the springs has been devoted to bathing pur- poses, and is conducted in iron pipes from the spring to bath-houses near by. The following temperatures were taken by Mr. Taggart : Temperatures June 12, 1873. Ss ene | tel S Bye ey a ce ae eee Name of spring. we fy ae HO Ee Oo .4 5) ro) oe a8 E Pe) | Bie ca a a P.M. © 2 FS] oVaYS) GVa OY =%5e4 05 APOE ye eng ee en ren ere el OS RES POSES ALN SIN NE ea ed AAD) iba (U0) 72 Navajo, or Bathing Spring...--.- iat elas tae are Nae once tee 12. 25 60 72 Manitou, or Doctor Spring...........-----.----------.2--- 12. 30 59 68.0 Wat tlex@hieh chs 2 Seis sO CEN SO Neen ae ee See ance 1.10 48 74 oie pee oe So te Soe ta Set Ree es eee tins ce eee ees 1.20 54 72 . Temperatures June 17, 1873. SEs 3 eh alin i c 2s i = ba Name of spring. aS aa mS g S| | -— o o A = i= A. M. ° ° ESS mays OV Op Usps, nn AUN NG GPs eA Ne Dee NE Ree oh as 9.25 59 77 INA Vg OR ecisein cach nein loiciavsin cle tetetenicihenistemnciemiswisietescenic 9. 30 58 78 IMA TITGO Wess Crees aiG 2 Se, Gate cise laoinvancio ties saree scins shetesioaecee 9. 35 58 78 Womanches jesse eS. wise wil sraenieiene e cperjeiteusalsia seein 9. 38 60 78 Wit hleiChiet seer ees ee eek ee eee sa ere ce) ean My ove erate ead) 45 74 Igoe Oh Bape eS Oe ANE Mawes means tse cimmerarseialsali (tO) (Dis) 48 72 Spring on road near Ute Pass... 222. 2252-2 ee = | O20 53 70 The Shoshone, the Navajo, the Manitou, and the Comancne are on the “Fontaine qui bouilé” all being on the right bank except the Mani- tou. The Shoshone gives off a great deal of gas, the Navajo a medium quantity, while the Manitou gives out very little. The latter has the best tasting water. The Iron Ute and the Little Chief are on Rux- ton’s Creek, a short distance above the ‘‘ Fontaine.” They are distinguished by having a larger percentage of iron than any of the rest. The “Little Chief” gives off a moderate amount of gas irregularly, while the “Iron Ute” is quiescent. The last spring given in the second table is on the bank of the Fontaine, near the Ute Pass road, a short distance below the falls. Its water is very agreeable to the taste, but as the spring is some distance from the others, it is not so generally used. Leaving the eastern side of the mountains, we fol- lowed the “ Fontaine” to its head, through the beautiful and picturesque PEALE] GEOLOGY—FONTAINE QUI BOUILE. 207 canon which it has cut in the granite. Near the head of the creek we again meet with the sedimentary formations, having a dip to the north and northwest. Following the beds to the northward, the dip turns more and more to the west. The northerly dip is, therefore, the result of the elevation of the mass of which Pike’s Peak is the center. Leaving the Fontaine, we cross to the head of Trout Creek, the branches of which drain the country to the northwest of Pike, and, flowing northward through Bergen Park, empty into the South Platte in the cafion. At the extreme head the creek is among granites and schists. Just above Bergen Park the main stream flows through a small caiion, in which we have outcrops of a dark purplish red sandstone, seemingly very much metamorphosed, and having a dip to the east. Just above this is a soft, grayish sandstone, on top of which is a red sandstone like that beneath. These outcrops are indistinct, and the angle of dip could not be ascer- tained. Emerging from this calon we come out into an open valley, in which there is a small settlement clustered about a saw-mill. The rocks are all covered with debris, and the eastern side is so heavily timbered that little can be seen. As we approach the range to the eastward we will doubtless find the same beds that we see so well exposed to the north- ward with a westerly dip. At the lower end of the valley the creek enters a cafion, of about a mile and a half in length,in the granites, from which it flows into Bergen Park. The park is about eight miles in length, and will average about three in width. It is, I think, the axis of a synclinal fold, although I cannot be positive, as everything on the western side is so much obscured. The beds seen in the small cafion referred to above dipping to the east, and a few indefinite exposures farther south seeming to dip in the same direction, point toward the existence of a synclinal fold, the center of which is filled with red sandstones, (Triassic.) Through this park the creek flows in a direction a little west of north. At the lower end we have monument-like masses of red standstone re- sembling those seen east of the mountains. These red-beds have a westerly dip, and incline at very low angles, not exceeding 10° to 15°. At the lower end of the park the creek enters a caiion-like valley, which is about a quarter of a mile in width. At the entrance to this valley there are on either side the massive red sandstones which on the west side rise in high bluffs. On the east side the surface of the country is more rounded and smoothed off, while we have numerous caiions cut by the streams that drain the western side of the Front range. Fol- lowing up the first small creek that joins the main stream after it en- ters the valley, we observe that the red-beds become lighter and lighter in color until they are pink. They are also conglomeritic. These lower layers are followed by massive white limestone; this limestone is suc- ceeded by white and pink shaly limestones, which are superimposed on sandstones that rest on the granite. The following is a section from the red-beds down. The thicknesses are estimated : . 1. Red -beds. 2. Red and pink conglomeritic sandstone.........-...----. 50 feet. BeeNASsiVe MMeSstONe .-2-- 6... ec Gee cece eee eee 100 feet EMV TIES IMESLONG’, - ins) ass eee fe sce eel decane § : meEink limestone, somewhat shaly.::-..2:2:20.0.0-- 22sec 30 feet. a STL SCE Sete iti e al dele li ae cll te ee Aaa 4 feet. Se erown purplish sandstone .........-.--.:--.--- siege 6 feet. 8. Yellow sandstone. 9. Granite. 208 GEOLOGICAL SURVEY OF THE TERRITORIES. The angle of inclination is 5 to 10°. As we go down Trout Creek the sedimentary beds are influenced by the mass of mountains to the northward. The strike of the beds crosses the creek, and instead of the bluffs on the west side of the creek being red sandstones, they are first the massive white limestone and then the pink limestones underlaid with sandstone. The creek then enters a granite cation, which has here and there isolated points © capped with remnants of the sandstones under the limestones of the sec- tion given above. The dip as we go down the creek changes more and more to the southward until, just above the canon, it is south 25° west. Still farther below it is south 85° west. The following sections are made across Trout Creek, just above the cation, the head of which is a few | miles below the foot of Bergen Park. Section No. 4is made through the bluff on the west side, while No. 5 is made on the east side; both are in ascending order: No. 4. No. 5. Feet. Feet. 1. Granitic. 2 rvellowy samdstone)(!oe/ 222) 54 So eB eed aes ae ee 73 65 FyoPimisi sia; Saw Stone: 2444. Gye aR AY es) ls Sal ; y } e: 4. Dark, purplish-brown sandstone. UI Sree toads ib Nea 16 13 5. Green SAMA SOME 52:4 se PE a eee SEL) Ve tas esa 4. 3 6. Blood-red caleareous sandstone ...........- sacteepth Ad 54 60 is EAM keiIMeSGON ES sera ashe Sey ee EN a SA rear } Beds No. 6 and 7 are fossiliferous, and belong in all probability to the Quebec group, while the sandstones below are Potsdam. In No. 61 found Lingulepis and Obolus, and in No.7 an Orthis, which Professor Meek says is very much like O. desmopleura, Meek. Also, Huomphalus, Asaphus, (Megalaspis,) Conocoryphe, Lingula, Bathyurus, and Paradoxides or Olenus. On the east side of the creek, in bed No. 2, are several small. faults, which are merely local. In the canon the course of the creek, instead of being north, is about northwest. It is there joined by West Creek, which, for most of its course, is parallel to Trout Creek, from which it is separated by a granite ridge. The canon at the time of the year we visited it was impassable. Ascending the hills we see all about us patches of sedimentary beds. In some places we have merely portions of the lower yellow sandstone, mostly soft, but often quartzitic, while in other places we will see all the sandstones and por- tions of the overlying pink limestones. Fig. — is a section from West Creek across Trout Creek and the plateau eastward to Pleasant Park, a distance of about eleven miles. It will be seen that the dip on the west side of the range is very much less than it is on the east side, and that the beds extend farther up on the plateau. This appears to indicate that the beds may have extended across the range. Section No. 6 was made at the point marked C in the Vig. 1, Plate V, and is from below upward. Section No. 6. Thickness in feet. ivedvlimestone, (fossiliterous) 2). 5.25 oe. ee ee see eee 26 Zoli ohiusia lym eS TOMS: -2) sles co on alone ee ee epee elidel havea 20 See COC MIMESTOMC See apie 5 kicie lo ka tee Heke clea (enna ee ocd ae 34 4, Purplish sandstone ............. ag De A Se Fee aes ar AP t dy Mottled timestome, .- see ss ee ae ee ae ee 3 6. Yellowish-white limestone.......... Shea ITI Le il a 20 NS IAL OCF w usprs ! 1/ He Mu LH; if Hit Sal [[— 2bref BWOiL OZ evoLs79 wojj0087 'G 91e[d ih nm a ne ver" ‘\esniat ty ipa tan aha al en Ai teen reste eit , " yy t ~ fies a PEALE.) GEOLOGY—SECTION NO. 6. 209 The lower part of the bluff is covered with débris, but as seen from the other sections made near this locality, is probably composed of the Potsdam sandstone. Bed No.1 contains Orthis, Bathyurus Saffordi, (Bil- lings,) and Lingulepis or Lingula. Whether the yellow limestone, bed 6, belongs to the Silurian or to the Carboniferous is uncertain. Careful search revealed no fossils. I think it probable that it is the equivalent of the Niagara limestone. The angle of inclination of these beds is 15°. Just above we have beds of massive white limestone. Going westward we pass over a rolling country which, as a few outcrops indicate, is un- derlaid by soft red and gray sandstones, the latter being above the red- beds, and dipping at an angle of from 10° to 12°. We then begin to ascend the hills, and find them so covered with débris that very little can be seen. I think, however, that the illustration, Fig. 1, Plate V, presents the correct view of the beds. The ridge above West Creek is eranitic, giving a red débris. The elevation of the ridge is about 7,556 feet. Returning to the east side of Trout Creek and following one of the little streams toward its source, we find that only the Silurian layers are to be seen resting on the granite. Section No.7 is made at the point B in Figs. 1 and 2, Plate V. Section No. 7. Thickness in feet. 1. Granitic. 2. White and yellowish sandstone .-.-...--.-------------- 43 ) «TESTI SRG RIMS Males oe on ecien soc COC eCta i GSE cerns 16 | 67 ft 4. Dark purplish-brown* sandstone ...........---.---++---- 5 ; Re REGU SAMOS LOMO aa apae om ~/ataleie Sosuepeieteieictelgunciels asus isinlalne = == 3 Meerick-red (shaly Jimestone 2.242 iva. 12 4-22 ame = te ae -l- 2 19 fo Pale-pink and eray limestones... 25.2.2 22- 55.2 s2.0. eee. 16 8. Pink limestones. About 6 feet below the top of bed No. 3 is a layer of pink quartzite which, at the point where the section was made, was only 2 feet in width. On following the bed northward, however, it increases to 4 or 5 feet. At the top of No. 3 is a shaly layer 2 feet thick, in red and pink bands. Nos. 4and 5 are alike except incolor. They are very coarse-grained and soft. The red limestones (No. 6) are full of green spots, probably glauconite. In the limestones the same fossils occur that we found on Trout Creek. They cap the hill. Between B and C in the figures on Plate V huge granite boulders are strewn over the surface. The granite is soft, and readily disintegrates. The feldspar is red orthoclase and the mica black. Masses in some places have weathered into forms resem- bling those found in Monument Park. At the point C we have only _ thelower sandstone, beds 2 and 3, and those here seem to be much changed. Standing on this hill we see all about us similar monuments capped with fragments of beds. We can also see Platte Mountain, to _ which we have alluded before. There seems to be aline of these jagged _ granitic points, the course of which is northwest and southeast, Platte Mountain and the Palisades, near the Platte River, being the most prom- inent. South of Platte Mountain these detached points show merely the general course. A comparison of the sections given above shows that the Potsdam group is represented by sandstones having a thickness of from 60 to 80 feet, while the beds that represent the Quebec group are a little over 100 feet thick. Comparing with the section (No.3) made at Glen Hyrie, we see that the beds on the west side of the range are 144G@s 210 GEOLOGICAL SURVEY OF THE TERRITORIES. thicker. Thus, instead of 60 to 80 feet of the Potsdam, in Glen Eyrie, we have only 40 feet. The beds correspond, beds 2 to 5 of section No. 4 being the same as 2 to 5 of No. 7. Soit is with the limestones above. At Glen Hyrie we have 73 feet where there are over a hundred on Trout Creek. Bed 14, of section No. 3, is, I think, the same as the white limestone above the pink shaly limestones on Trout Creek. Returning again to the head of Trout Creek we cross into Hayden Park. This name has been given to the low rolling country to the west of Pike’s Peak. Hayden Park is drained by Trout Creek, West Creek, and Beaver Creek. The latter flows to the northwest, and empties into the South Platte just below the upper cafon. About five miles from its mouth, around the settlement of Florissant, is an irregular basin filled with modern lake deposits. The entire basin is not more than five miles in diameter. The deposits extend up the brauches of the creek, which all unite near Florissant. Between the branches are granite islands appearing above the beds, which themselves rest on the granite. Just below Florissant, on the north side of the road, are bluffs not over. 50 feet in height, in which are good exposures of the various beds. The following section gives them from the top downward: © 1. Coarse conglomeritic sandstone. _ 2. Fine-grained, soft, yellowish-white sandstone, with bands that are more or lessargillaceous, and containing fragments and stems of leaves. 3. Coarse gray and yellow sandstone. 4, Chocolate-colored clay shales with fossil leaves. At the upper part these shales are black and below pass into 5, Whitish clay shales. These last form the base of the hill. THe beds are all horizon- tal. Scattered around are fragments of a trachyte which probably caps the beds. In one of the valleys, Mr. Taggart discovered, near an old well, pieces of trachyte, which, on looking at the excavation, was found to be the first layer penetrated. The point of overflow from which this material came is probably to the southward, in Dr. Endlich’s dis- trict. The lake basin may possibly be one of a chain of lakes that ex- tended southward. I had thought it possible that the beds were of Pliocene age. The specimens obtained from bed No. 4, of the section above, were submitted to Professor Lesquereux, who informs me that they are ‘“ Upper Tertiary.” ‘But I do not believe, as yet, that the specimens of the Green River group to which your species are referable, authorize the conclusion of Pliocene age. I rather consider it, as yet, as Upper Miocene. Thespecies known of our Upper Tertiary are as yet too few and represented in poor specimens for definitive conclusion. Your specimens have a Myrica, a Cassia, fragments of Salix augusta, (A. Br.,) a Rhus, an Ulmus, and a fragment of a Poa or Poacites.” The shales were so soit and friable that it was rather difficult to ob- tain any specimens. . About one mile south of Florissant, at the base of a small hill of sand- stone, capped with conglomerate, are 20 or 30 stumps of silicified woed. This locality has been called “ Petrified Stumps” by the people in the vicinity. The specimens of wood are not particularly good. The upper cafion of the South Platte River is about eight miles in length, and marks the exit of the river from South Park. The range in which it is, if it deserve that name, is the eastern boundary of the park. The rock is all granitic to the northward and to the northeast. South of the cafion is an area of volcanic overflow which extends south- ward into Dr. Endlich’s district, and I will only refer to it again in prate] GEOLOGY—UPPER CANON OF THE SOUTH PLATTE. 211 the next chapter in connection with South Park. The rocks to the north of the caiion were very carefully studied as far as the time would permit by Mr. Taggart, and I will therefore quote largely from his notes. ‘Going south from the road that leads from Colorado Springs to South Park isa granitic ridge running out into the park, and having a westerly direction. Passing southward we find a light grayish granite standing up in rough, jagged points. They seem, looking at them from one side, to have been thrust up through the coarse beds that lie about it. More conclusive proof of this was found farther along on the south- ern slope, where I could see the coarse beds tipped up against the lighter-colored and more compact granite, with a dip of about 10°. They then sloped gradually to the bottom of a narrow valley, which is the axis of a synclinal fold, for on the opposite side were the same beds and resting on the same kind of granite. Passing still farther along the ridge I found still another synclinal. The compact granite rises in sharp conical peaks. After passing three of these peaks the ridge be- comes flatter and continues to the caiion. As we skirt the base of the ridge we find first a red feldspathic schist bending slightly against the base of the third cone. The dip is west of north, at an angle of not more than 5°. Still farther along we find beds of micaceous gneiss dipping in the same direction, at an angle of 10°. This is followed by a very coarse and then fine, compact granite. The bedding one mile from the cafion shows a dip of 60° to the northwest. As we go toward the caflon it increases. Beyond the cation the beds continue dipping at about the same angle as in the cation. “ Going eastward along the cation, the same beds with the same dip are exposed. The granites are much broken at right angles to the bedding, so much so as to make it somewhat difficult to determine the inclination. To the south of the cafion there is a gradual rise in the ridge until it terminates in a high cone. ‘North of the road is a ridge with a series of high points and rather open valleys between. The highest of these points is the one next the opening through which the road to Fair Play passes. This ridge is not a continuation of the one described above, but is parallel with it. The latter is more to the south and west, and the axis of upheaval seems to pass out under the park. The other ridge extends about five miles to the southeast, and presents the same general features as the one first described. The eastern part is low, rising gradually toward the north until within a few miles of the northern extremity, when the greatest height is attained in a conical peak of light gray granite, then gradually sloping to the park, the slope being broken by afew valleys. On station 35, one of the points north of the road about half a mile, the gneiss dips nearly north.” In the irregular triangular space between this range of hills on the east side of the park, which Mr. Taggart refers to above, and the Platte River and Tarryall Creek, is a beautiful rolling park-like country, which, although for the most part covered with débris, is plainly seen to be underlaid by granitic rocks. The following is from the notes of Mr. Taggart: “On the northeast side of Tarryall Creek are three high ridges, the general trend being northwest and southeast. There are two main ridges which to the north unite, inclosing a third which has aless elevation. The dip on the southwest side is to the southwest, forming a synclinal with the ridge on the east side of the park. On the Summit the beds are horizontal, and then there is a dip to the northeast, and another synclinal is formed with the ridge farthest removed, form- ing the saddle northwest of the middle ridge. On the southwestern 212 GEOLOGICAL SURVEY OF THE TERRITORIES. slope of the second main ridge there are very few outcrops to be seen through the trees which cover it. At the northwest end there is a dip to the northwest, while at the opposite end the dip is to the southeast.” In passing up Tarryall Creek the prevailing dips are to the northeast and southwest. The dip is the same in the country about the North Fork of the Platte, as is shown by the course of the stream, which is about parallel to that of Tarryall Creek. The latter, as far as could be ascertained, flows through a synclinal axis. Along the Platte River are high masses rising in dome-shapes above the cation. The study of this part of the country would require the work of almost an entire season. The different streams should be followed, and this can be done only in the latter part of the season. We were there in June, and I attempted to follow the Platte River, but found it impossible, not only on account of the rough and difficult traveling, but also because the stream was then atits highest point. The whole country is probably archean. There may be, and most likely are, points of eruptive material, but, as I have said above, close study will be required to work up this district thoroughly. Our time was too limited to do more than take a general glance at the most salient features. We have seen that on the North Fork and on Tarryail Creek the strike is from northwest to southeast, and that as we go south this changes and becomes northeast and south- west. This change is shown also by the change in the course of the Platte when it enters the upper canon. Before that it flows from the northwest, but in the cafon its course is toward the northeast. (OV ISH VL 12) 40 29) Te9)) IC IE SOUTH PARK—PARK RANGE. ‘This chapter will be devoted to the consideration of the remainder of the district lying to the east of the continental divide. This comprises South Park. The park is about forty-five miles in length, and somewhat irregular in shape, being widest at the southern end, where it is about forty miles from east to west. Its surface is very irregular. As the drainage shows, there is a gradual slope from the northwest toward the southeast. At the northwest end, the elevation is from 9,372 to 9,981 feet above sea-level. The elevation of Fair Play is 9,764 feet. As we go east this decreases until we have an elevation of a little over 8,000 feet, and aS we go south we notice the same gradual decrease. Thus, at the salt-works the elevation is 8,573 feet. In the southern por- tion of the park, the elevation is more uniform than in the northern part. Still, the slope is toward the southeast, and where the South Platte enters the canon the elevation is only 7,991 feet. There are numerous ridges running through the park, generally parallel to each other. Thus, starting at Fair Play and going eastward, the first is a low ridge a couple of hundred feet in height. Crossing this, we descend to Crooked Creek, and then ascend a second ridge that rises 500 feet above the val- ley. On the east side of this ridge is the valley of Trout Creek, and beyond it a third ridge rising to about the same height, perhaps a few feet higher. East of this is a low rolling country extending for some three or four hundred miles, bounded by a series of rounded hilis rising about 600 or 800 feet above the general surface. These hills extend for a few miles, and then there is a space having an almost uniform level ME Yaar AN, MAN oh 2G 7 ; a uy, a in ate it PLATS. VI. South Prette Trout Creek SS 6S Kigl Section across South Park Fig Section across the Little Plitte Big.d Section near Hooster Pass Mt. Lincoln FG 6 Section though Mt. Bross Little Platte Fig.7 = Sectron neross the Little Platte ahoye the Salt Works Fig. 8 Section through Buffalo Pech SRT SAN Fate Rat yoe PEALE.] GEOLOGY—SOUTH PARK. 213 from which the hills bounding the park on the westrise. In the south end of the park are numerous isolated buttes, the majority being of yoleanic origin, although some are composed in part of sedimentary for- mations. They will be referred to again in subsequent portions of the chapter. Almost the entire southern end of the park is volcanic, and the country gradually rises from the South Platte River to the divide, and then slopes to the Arkansas River. The outlet of the lake existing here in early Tertiary times was probably in this direction. The erup- tive forces acting after the deposition of the lignitic sandstones elevated this part of the country, and the water had to find an outlet in a new , direction. It was then that the present drainage was probably out- lined. The lake was most likely drained through the Platte caton at the southeast end of the park. The lake itself must have extended farther to the southward than the present outlines of South Park would seem to indicate. The mountains on the east side of the park, as we saw in the last chapter, are composed of schistose rocks which extend westward some distance into the Park. The outline is rather irregular, but the general course of the range is northwest and southeast, and, as we have seen, the dips are to the northeast and southwest. The range is therefore an auticlinal axis, which, as we go south, bends to the east- ward. The elevation is over 10,000 feet above sea-level and over 1,500 feet above the park. The northeast boundary of the park is a continu- ation of the schists, identical with those on the east except that here the hills are capped very frequently with eruptive material, mostly trachyte. On the more uniform level of the park, the sandstones are but little dis- turbed. As we shall see further on they are of Tertiary age. The vol- canie rock extends around the northern edge of the park, close to it, not extending far to the northward until we get around to the northwest. It seems to have been an overflow, as I found in several places that it capped hills whose bases were composed of dark micaceous gneiss. The hills that rise above to the northward are also metamorphic. On one of the branches of Michigan Creek, extending some distance up the valley, is a tongue of sandstone, a prolongation from those in the park, proba- bly outlining an old bay. The upper edge of this narrow belt, bounded on one side by trachyte, and on the other by granite, was found by Mr. Gardner to be 500 feet above the general level of the park. A period of elevation in therange north of the park, therefore, must have taken place after the deposition of thissandstone. The granites and schists form the basis of the range north of the park until we get to Mount Guyot, when eruptive rocks are seen at the head of Michigan Creek, near Mount Guyot. This mountain has an elevation of 13,389 feet, and is on the continental divide, which, on the west side of the Arkansas, has a di- rection nearly north and south, and then turns to the east around the head of the river, and again, beyond Mount Guyot, turns abruptly to the northward toward Gray’s Peak. Just east of the mountain is a low sad- dle, forming the water-divide between Michigan Creek and the waters _ of Snake River, one of the tributaries of the Blue River. On this saddle (Georgia Pass) we have the following section, shown in Fig. 4, Plate VI: ; (a.) 1. Erupture granite forming the peak. (b.) 2. Hard gray slate. (c.) 3. Quartzite. (d.) 4. Coarse gneiss, light colored. (€ 214 GEOLOGICAL SURVEY OF THE TERRITORIES. mica. The quartzite and slate are both very much changed, and are each about 60 feet in thickness. Theslate weathers on the surface arusty-brown color. The dip is south 55° east; angle of inclination, 50°. Iam ata loss as to the position of these beds. They are fragments that have been caught and lifted up, but they are so changed and too few in num- ber to say anything definite of them. They could not be traced to the southward, and our time was too limited to try and follow them to the northward. ‘The mountain itself is composed of a fine-grained granite of a gray color, and, I take it, is eruptive. In it are seams of a dark- green porphyritic rock, in which the matrix is very compact, the crystals being a white feldspar. The mountain has been called Crater Mountain, a name derived from its peculiar crater-like shape. Ascending the eastern side on a slope of about 30° over a mass of shingle-like débris, on reaching the summit we are on the edge of a crater-like depression, the walls being perfect, except on the southern side. It is not, however, a true crater, the shape being the result, in all probability, of erosion, due partly, per- haps, to past glacial action. ‘This form is common in the mountains on the west side of the park and in the Sawatch Range on the west side of the Arkansas. In the latter we have abundant evidence of former glacial action in the moraines, which, as we shall see further on, are found along all the streams. Besides the depression below the main peak there are three others, two facing the south and one looking toward the north. Between Tarryall Creek and Michigan Creek are high hills or mountains composed of aporphyritic volcanic rock, approaching the character of a phonolytic trachyte. The summits of these hills are rounded, and their slopes are covered with slab-like masses, which, on the surface, weather to a rusty color, and ring under the blows of the hammer. Following the edge of these hills around to the town of Ham- ilton, on Tarryall Creek, and then going up stream a short distance above the town, an outcrop of quartzite appears, dipping a few degrees- to the south of east under the voleanic (?) rock. At this point is an abrupt turn in the course of the creek. Until it reaches this place it follows the strike of the quartzite, but here breaks through them at right angles. Beneath the quartzite is a soft grayish-white sandstone, and in the banks of the creek are exposures of red sandstone. The quartzite and gray sandstones are, doubtless, Cretaceous No. 1, and a continuation of beds farther southward, between Trout Creek and Crooked Creek. They are in line with them, and the strike corresponds precisely. The red sandstones are Triassic, and have a dip of about 5°. They form the bed-rock upon which the auriferous gravel rests. This gravelis about 10 feet thick, and has yielded a great; deal of gold. The mines in this vicinity are treated of in Dr. Endlich’s — report. About five miles west of Hamilton is the mountain called Silver Heels, having an elevation of 13,731 feet. We ascended it, and on the eastern slope I made a partial section of it, as follows: Section No. 8. 1. The summit of the peak is made up of an eruptive rock resembling that in the hills above Hamilton. This, with a few layers of coarse micaceous sandstone, sometimes conglomeritic, extends for about 1,500 feet. The slope here is very small, only about 5°, and the beds are so covered with débris that it is impossible to define them. 2. Metamorphosed sandstone and volcanic rock. The sandstone con- tains rather large rounded pebbles. The volcanic rock is beneath PEALE. | GEOLOGY—SECTION NO. 8. 215 the sandstone, and is probably trachyte. The thickness of both is 117 feet. . Green and purplish sandstone shales, very much metamorphosed, 60 feet. . Voleanic, (trachyte ?) 4 feet. . Purple metamorphosed slates, 5 feet. . Volcanic, (trachyte ?) 4 feet. . Coarse brown sandstone, very much metamorphosed, but rather uniform in structure, 100 feet. . Voleanic, (trachyte ?) about 20 feet. . Very hard, dark sandstone, in layers, 6 or 8 inches, 50 feet. . Light- brownish sandstone with streaks of dark-brown, 30 feet. . Volcanic, (trachyte ?) 20 feet. . Dark-gray sandstone, 70 feet. . Voleanic, darker than the other layers. The lower portion is covered with débris. Thickness, about 80 feet. . Red shales very much metamorphosed. These shales break into lamine of about an inch thickness, and are micaceous. There are mud and rain marks between the lamine, 8 feet. 5. Greenish-gray quartzitic sandstone, 10 feet. . Voleanic: this layer has a wedge-shape, and on the surface its thickness is about 20 feet. . Red shales, 10 feet. . Pinkish sandstone, very irregular in structure, 8 feet. . Red shales, 10 feet. . Light-gray conglomeritic sandstone, 4 feet. . Red shales, 4 feet. . Gray sandstone, becoming coarse toward the bottom, having lar ge pebbles: above, it has a pinkish tinge; 10 feet. . Hard-red sandstone in lamine of 2 to 3 inches, 5 feet. . Compact sandstone, with general color gray, but becoming pinkish as we go down, 30 feet. . Red shales, 4 feet. . Compact sandstone, pinkish and calcareous above, gray below, 5 feet. . Dark-blue limestone, containing veins of calcite, and without fossils, 2 feet. . Red and purple shales, darker in color than those given above, 3 feet. . Compact sandstone, light-gray, 5 feet. . Red shales, 2 feet. . Voleanic, (trachyte ?) 6 feet. . Dark purplish-red sandstone, breaking into blocks, 30 feet. . Red and purplish shales, 3 feet. . Greenish. gray sandstone, banded and streaked with green in layers from 2 to 3 feet thick, some conglomeritic, 25 feet. . Hard, red sandstone shales, 2 2 feet. . Hard, red sandstone, 1 foot. . Greenish. gray sandstone, with bands of brown sandstone shale from 1 foot to 2 feet thick, 15: feet. . Red shale, 1 foot. . Brown-banded sandstone, with bands of volcanic, 50 feet. . Red, gray, and purplish sandstones, 20 feet. . Greenish conglomeritic sandstone, 6 feet. . Brown sandstone, 8 feet. . Very hard greenish sandstone, 6 feet. . Light-gray sandstone, 10 feet. . Voleanic; could not get thickness. 216 GEOLOGICAL SURVEY OF THE TERRITORIES. From this point, there is a slope with occasional outcrops of red shales and greenish sandstones, all rather coarse. These no doubt continue to the red-beds (Triassic ?), above which is Cretaceous No. 1, to which I referred above as crossing Tarryall Creek above Ham- ilton. Beyond this is a hill of the same material as that resting on the same bed (Cretaceous No. 1) on the north side of the creek. This Slopes to the park, where the Tertiary sandstones appear. The distances in the section given above are all estimated. For want of time, I was unable to carry the section any farther to the eastward, but the sections made in the park at points farther southward comprehend it. Silver Heels is drained on the south by the branches of the South Platte, and is hol- lowed out, leaving the high ridge on which the section is made standing out prominently. Thevolcanic layers seem to be intruded masses which have so changed the sedimentary beds and hardened them that they have been able to resist the eroding influences, and the result is this prominent ridge. Leaving Hamilton, and still keeping close to the edge of the mountains, in going around the northwest rim of the park, we notice after crossing Tarryall Creek that the Tertiary formations extend to the edge of the mountains, which here are voleanic. Near McLaugh- lin’s ranch is a coal-mine. This was visited by Dr. Hayden, and will no doubt be fully treated of by him. The Tertiary beds here are so cov- ered with drift that they are almost entirely concealed. Following the road southward we pass around the edge of a trachytic hill, and come across cretaceous Shales belonging in all probability to the Fort Pierre group, (No. 4.) They are found in a valley between the hill just referred to and a low volcanic ridge that runs out into the park. Crossing this ridge we again pass over the shales. Here is a well-marked terrace on a small branch of Tarryall Creek. Itis about 100 feet in height. Ter- races are to be seen on almost all of the branches of Tarryall in the northwestern part of the park. Just south of the terrace referred to is a long volcanic ridge, the course of which is almost due north and south. I have already spoken of this ridge, which is shown in the profile across the northern end of the park. The following section was made from the Platte River eastward to Trout Creek, about five miles north of Fair Play, and is shown in Fig. 1, Plate VI. The length of the section No. 9, given below, is about six miles. The distances and thicknesses are es- timated, the average dip being about 30° toward the eastward. Section No. 9 a.1. Starting from the Platte River, the point a in the illustration, we have the valley covered with drift to the edge of the hills, a dis- tance of about a mile. We then begin to ascend the hills, which are well timbered, concealing the beds. From the character of the débri ts, I think there is volcanic IOC beneath. The first exposure we met with furnished— b. 2. Red sandstone dholese thickness, 400 to 500 feet. Then followed: . Gray shaly sandstone. . Brownish limestone. . Red shales. . Very coarse white micaceous sandstone. These beds are indi- cated by very indistinct outcrops, and are from 500 to 600 feet. Then we have next— c. 7, Limestone mostly of a grayish color ¢ or grayish-blue, in some places brownish, compact in some layers, and then again ir- regular, with seams of calcite. Thickness, 6 feet. co OU Oo PEALE. ] d. 8. GEOLOGY—SECTION NO. 9. 2G Space: this is marked by the letter d in the illustration, and is the valley of Beaver Creek. The beds are covered up. Proba- bly a thickness of 700 or 800 feet. Very coarse and somewhat massive red sandstones, about 100 feet. . Space of about 400 feet, . Dark-blue limestone, 5 feet. . Space with a few indistinct outcrops of sandstone and lime- stone, about 700 feet. . Coarse red sandstones in massive layers, 300 feet. . Space probably filled with sandstone at bottom, shale above, 300 feet. . Deep-red shales, 90 to 100 feet. . Blue limestone, 4 to 6 feet. . Red sandstone, coarse and shaly micaceous, 30 feet. . Gray micaceous sandstone, about 5 feet. . Dark-blue limestone, 2 feet. . Space filled with shales, 3 feet. . Dark-blue limestone, with irregular structure, 5 feet. . Mottled red and white sandstone shales, weathering red, 5 feet. . Blue limestone, coarser than below, and in thin layers, 2 feet. . Space covered up, but filled in all probability with shales and interlaminated limestones, about 120 feet. . Dark-blue limestone, 2 feet. . Very coarse soft shaly sandstones, below and next to the lime- stone, having rounded pebbles of quartz. At the top they are finer grained and softer; the color becomes deeper as we get toward the middle, where it is brick-red, and then becomes pink at the top, 10 feet. . Blue limestone, 1 to 3 feet. . Space probably filled with shales, 40 to 50 feet. . White and red micaceous shaly sandstones, 40 feet. . Coarse sandstones, 10 feet. . Dark-blue limestone, 4 feet. . Space covered up, but filled in all Byabaiitey with sand ies + feet. . Blue limestone, 4 feet. . Space shales, (?) 90 to 100 feet. . Dark-blue limestone, 2 to 3 feet. . Red and white sandstone, 16 feet. . Dark-blue limestone, 3 feet. . Space sandstones, (?) 100 feet. . Coarse and somewhat massive brick-red sandstones, 50 feet. . Space sandstone, (?) 20 feet. . Coarse red sandstone like No. 39, 50 feet. . Space sandstone, (?) 15 feet. . Dark-blue limestone, 3 feet. . Space covered up; indications are that sandstones and shales entered through it, 60 to 70 feet. . Dark-blue limestone, 4 feet. . Space sandstones, (?) 32 feet. . Blue limestone, 5 feet. . Space sandstones, (?) 150 feet. . Blue limestone, 3 feet. . Space sandstone, 350 feet. . Blue limestone, 3 feet. 218 GEOLOGICAL SURVEY OF THE TERRITORIES. ( 52. Space, the valley of Crooked Creek. On theeast side of the valley we havethe massive red sandstones (Triassic?) with all the charae- teristics of the same beds east of the foot-hills, and on Trout Creek west of them. It is probable they extend down to bed 51. Their softness has allowed them to be worn down, and they have been covered with débris. The total thickness is from 1,300 to 1,500 feet. 3 Coarse pink sandstones, 25 feet. | 3. Fine-grained rose-colored sandstone, 8 feet. These two beds are the upper part of the red-beds. J > d4, Rather coarse calcareous sandstones, shales mottled red and gray, 5 feet. 55. Space probably filled with a continuation of 54 grading into the | next bed, 30 feet. 56. Gray compact limestone. This limestone has cross cleavage, | and becomes harder as we go up, 10 feet. 57. Hard fine-grained limestone, light gray, 15 feet. 58. Space probably filled with limestones and shales, 75 feet. 59. Outcrop of green shales, 10-feet. 60. Space filled with shales and sandstones, 60 feet. . Rusty yellow sandstone, 5 feet. . fine-grained white sandstone with fragments of stems and leaves, 5 feet. . Space sandstones, (?) 20 feet. Yellow sandstone, 40 feet. . . Space sandstone, 80 feet. . Space filled with shales, (?) 500 to 600 feet. . Dark-gray fossiliferous limestone, 2 feet. . Space, probably Limestone 20 feet. . Black argillaceous shales, 2 feet. . Space shales, (?) about 700 feet. . Caleareous sandstone shales, 60 feet. . Space shales, (?) 300 to 400 feet. . Black and green shales, fossiliferous with interlaminated lime- stone bands, 400 feet. From this point to Trout Creek, a distance of about half a mile, ; ; are no exposures, the beds being covered with drift. When é we reach Trout Creek it is evident that we have crossed a synclinal axis, for the dip now is toward the westward instead of east as before. On the bluff the beds are as follows: 74. Black argillaceous shales, outcrop 2 to 3 feet. 75. Bluish-black limestone, 1 foot. 76. Black shales, about 180 feet. This brings us to the bed of Trout Creek, and crossing it black shales prevail until we reach the volcanic ridge which doubtless caused the fold just referred to. This ridge, A in the figure, is about 400 or 500 feet high, and extends north and south. It is trachytic. A low hill between the two branches of Trout Creek south of the hill marked 7 is of the same rock. Whether the eastern side of the fold extends along the ridge to the southward or not I could not determine, as the valley was covered with débris, and there were no exposures on the east side until we came to the voleanic rock itself. The line of the section given above is from the northwest to southeast, and with the exception of the beds from No. 18 to No. 51 is a continuous section. The portion of the section between these points was made farther southward, but connects with the others. At the point where the greater part. of the section was = S> D> be ———) ——— > ——_ | = ADDAAADA SD aa4 WNEROSOSHAASUE S a GEOLOGY—SECTION NO. 9. 219 made these beds were entirely concealed. All the beds below No. 52 are probably to be referred to the Carboniferous and Permian systems, although I cannot so refer them positively as there were no fossils found to prove it. The red-beds (Triassic?) have a thickness of about 1,500 feet, which is about the same as we found east of the mountains. Cre- taceous No.1 (Dakota group) is somewhat thinner, while the Jurassic (?) between has about the same thickness as seen heretofore. The entire thickness of the Cretaceous as shown here (beds 61 to 73 inclusive) is over 2,000 feet. The beds have about the same characters as the analo- gous beds east of the mountains. The illustration Fig. 1, Plate VI, car- ries the section still farther to the eastward. Around the northern end of the ridge “A” (trachyte) are, as indicated by the débris, Cretaceous shales. No definite exposure was observed, and it was impossible to tell whether or not the shales extended around to the eastern side, and if they did, in what direction they inclined. On the east of the ridge is a grass-covered valley (k) about a mile in width, from which, going east- ward, we ascend a low hill rising about 200 feet above the valley. On the west side of this hill are outcrops of trachyte, seemingly stratified and dipping toward the east.: On reaching the summit we find that it is plateau-like, cut into low hills by small gullies. Crossing toward the eastward in one of these gullies, the following beds are exposed (the point J in the illustration) from below upward: 1. Volcanic breccia. 2. Sandstone. 53. Volcanic breccia. 4, Breccia looking very sandy. The entire thickness is not more than 50 or 60 feet. The dip here, how- ever, is not to the east, but west. The angle of inclination is only 20°. Be- tween the points & and J/is, therefore, a synclinal fold. The sandstone is a dark greenish brown, very much metamorphosed; some of the layers look like a voleanic sandstone. The breccia seems to be interstratified in places, but is probably, in part, intruded, as in some places the sand- stones on both sides are much changed. Still farther east, at the point m, are similar beds, with the dip once more to the eastward. From this point we descend into a broad valley, in which the beds are, for the most part, covered up. Here are a few small lakes, with no outlet, and the ground about them is covered with alkali. The valley is somewhat roll- ing in character, not uniformly level, but having a gradual slope to the east. Jt is underlaid by sandstones, and is a mile in width. On the eastern side, on ascending a low ridge rising about 40 feet above the valley, an outcrop of white shaly sandstones is seen, below which is vol- canic breccia. The dip here is south 80° west; so the valley we have just crossed (mv) is another synclinal. The angle of dip is about 25° or 30°. There are three or four of these low ridges that are parallel to each other; the general strike being north 10° west. The first two, at 0, in the section, form an anticlinal. From m to m are exposures of light-gray sandstones, somewhat fine grained, with interlaminated coarser sand- stones of a dark-brownish color. The outcrops are not very decided. At 0, in a bed of rather coarse sandstone, [ found fossil leaves, among which Professor Lesquereux has recognized Rhamnus Poldianus, Platanus Hay- denii, and a fragment of a leaf of a Quercus new to this country, and related to Quercus Heerii, Al. Br. ‘The flora, he says, is Lower Tertiary, and represents the lignitic group. From o to pis a distance of about an eighth of a mile. From the latter point we have a meadow-like val- ley about a mile in width, from which we ascend granitic hills. This valley is another synclinal axis. The hills are at B in the section, and 220 GEOLOGICAL SURVEY OF THE TERRITORIES. are about 500 feet high, rounded in outline, and extending about three miles in width. On the east we descend into another valley, C, in which all the rocks are concealed by the drift. Ihave little doubt, ‘however, that it is underlaid by Tertiary sandstones. This valley is ‘somewhat irregular in shape; but in the section it is represented at C as about six miles in width. From q to r the line on which the section is made is changed, and has a course of south 45° east. The Tertiary sandstones, whieh we have just spoken of, are the same that we noticed extending to the edge of the trachytiec hills i in the northern and northwestern part of the park. We have seen that they extend across the park in a wave- like manner, occasioned, no doubt, by voleanic action that was contem- poraneous with the elevation of the voleanic ridge on the east side of Trout Creek. Returning to this ridge, and following it southward, we observe that it turns more and more to the eastward; and this fact is also rendered evident when we notice the course of the streams that are parallel to it. At Station No. 92, a high point to the southeast, which seems to mark the termination of the ridge, we have, on the south side © and dipping toward the south, as I learn from the notes of Mr. Taggart, an outcrop of sandstone, somewhat metamorphosed. ‘This I take to be the bed of sandstone so characteristically marked as Cretaceous No. 1. It evidently belongs to the western side of the synclinal fold, to which L have already referred as existing at the head of Trout Creek. Still far- ther down the river, and on the eastern or rather northeastern side, is another butte, in which I found exposures of beds belonging to the Da- kota group. The sandstone here, being very much metamorphosed, is quartzitic. Just above it are the same Shales that we saw in other places, and the limestone, with Cretaceous fossils, (bed No. 2, in section No. 1, and No. 67, in section No. 9.) These beds all dip to the southwest at an angle of 50° to 60°, and are, I take it, a prolongation of the eastern side of the fold on Trout Creek, and at the butte (Station No. 92) referred to by Mr. Taggart. The volcanic ridge, which is the cause of the uplift on the eastern side, making a turn to the eastward, of course, the strike of the sedimentary beds is also to be found turning in that direction. At the base of the butte just referred to are remnants of a soft sandstone, which I consider to be of Tertiary age, whether Eocene or more modern I could not determine. Before leaving this butte I will describe the springs that are at the south end. They are all saline. There are four principal springs, although there are beside a number of places where the water bubbles up. Spring No. 1 is about two feet in diameter and three feet in depth, and has no doubt been artificially enlarged. At intervals of a few seconds there is a slight escape of gas, probably all carbonic acid. The water has rather a pleasant taste, though by no means as agreeable as that in the springs at Manitou. It is saline, somewhat pungent, tasting slightly also of sulphur. The temperature of the water was 58° Fahrenheit; the air being 78° Fahrenheit. Spring No. 2 is about 6 feet below No. 1,and about a foot in diameter and 6 inches deep. The water tastes very much like that of No. 1, although not quite so pungent, nor is there as large an escape of eas. The temperature was the same as that of No. 1. Spring No. 3 is very little different from the other two. It is about 4 feet from No. 2, and has a greater evolution of gas. The temperature is still 58°. Spring No. 4 is about 30 feet from No. 3, and about a foot in diameter and 6 inches deep. It is a very quiet spring, the water tasting strongly of salt, and also slightly of sulphur. Between No. 3 and No. 4 is a marshy space, in which, by a little digging, a spring could be formed. PEALE] GEOLOGY—SECTION NO. 10. 221 At this place is a considerable deposit of iron not noticed in the springs. For some distance about the springs there is an efflorescence of salt and alkali. The principal constituents of the water are common salt, sul- phur, iron, and carbonates. Southeast of the butte, at the base of which we find these springs, is a double-topped butte, which I found to be composed entirely of granite. The rock was somewhat covered, but I consider it to ke a remnant of a line that once extended northward, and that the rocks probably incline to the southwest or to the northeast. The whole southern end of the park, as I learn from the notes of Mr. Taggart, is volcanic. The Platte River for some distance follows a course very near the line between the trachyte and the sedimentary formations. On this line are several buttes, on the northern end of which are granite outcrops, while the rest of the butte is either trachytic or basaltic. Following the river up from the cafion we find that it fows through schists for about five or six miles. We then meet with trachyte, which at this point is found on the south side of the river. As we near the salt-works we find numerous isolated buttes of trachyte, many of them having a conical shape. A line of these buttes extends from the Little Platte, about eight miles above its mouth, toward the southwest. They mark the limit of the volcanic rock in this direction. The Little Platte forms the boundary from the mouth up for eight miles. The main river for about eight or ten miles above the mouth of the Little Platte flows in the axis of a synclinal fold, the same to which I have several times already referred. The fold is here much broader than at the head of Trout Creek, where we first observed it. Above the mouth of Trout Creek, the Platte River cuts through the beds after being for some distance on a monoclinal valley in the red-beds. Above, at Fair Play, its course is again across the strike of the beds. Here it has cut deeply into deposits of gravel, which are probably the result of glacial action. This may also account for the course of the stream at this point, as its bed may have been determined by a glacier. Near Fair Play, the gravel, which is auriferous, is from 70 to 100 feet thick, com- posed of rather large rounded boulders. Between the Platte River and the mountains that form the western boundary of the park, the country is rather uniformly level, and so covered with drift that we have very few exposures of rocks. Itis not until wereach the Little Platte, about ten miles south of Fair Play, that we have any definite exposures. At this point, near a bend in the creek, I made the following sections, sec- tion No. 10 being made at the point A in Fig. 2, Plate VI, and section No. 11 from the point B to C. The dip of the beds on the bluff where section No. 10 was made is about south 75° west; angle of inclination, 25° to 30°. Section No. 10. In ascending order: Mer S TI AShOME 2c foie ia tei eis. a's -s oe bee \ 59 feat PACE, COMELEU. Ups =\o 2:05 occ ech es Seabee neater et La (Oaks ; pareinelnmestoness 10:4 feeb. cae steeds ee sk ess 91 feet TAU COVETCE: Us cc ot iy ve let utah s OR iead sede nee i h EEE SUS ATLOSUONGS.- oc facie, one d acs Saves ac gis cs o's so aie 120 feet. 6. Space probably filled with alternation of sandstones and UENO) eee ARE eile ey ee ie op eh eae a 120 feet. fe bine bimestone)4 to d feet... 6.6... fees es eee eee ! 69 feet PRICE OGELCON TID) scien lisks Sits cs ok seb e cca ete cee ard : = 222 GEOLOGICAL SURVEY OF THE TERRITORIES. OLR EUESANCSTOME pooh Lhe Wake ck Ulu Dest | WIA cet eget a Me uNseE ee 70 £ 10.; Spacecoverediaupe se. sae ee cl. leanne aig ; ee et. ight or ay SamMascOme cs = 4 ies eis Sere ae el oe eee Cas 12. Red SAMO SEOMC Epes Mics le av elel aac atelinhs ata aie i a aun § o2 feet. Hoe) WE MoM eS POM OE se ie aoc ic eesenia ta ear eal es es SLO Aca ae 10 feet. 4 Red SAG SOME SMaAles 4). eis severe aracerc ele Deena & SeGney eens 8 feet. 15. Dark-gray argillaceous sandy shales, breaking into fine layers, between which are crystals of pseudo-malachite 10 feet. HO Med samd svome SHalespre seer cyes we tees Oley i nee 25 feet. A. Mont omay SANG STONE sii. G oye won nec enlgu te Wer area a 8 feet. b.18. Very dark blue, almost black, limestone.... ....-...-- 5 feet. These beds are, I think, a portion of those just below the red-beds included in section No. 9, between beds 17 and 51. I am inclined to refer them all to the Permian or Permo-Carboniferous. At any rate, if not Permian, they are high up in the Carboniferous. I shall refer to them again in a subsequent chapter, when I have occasion to speak of similar rocks found on the Hagle River, a eens of the Grand River. Between the points A and “B in Fig. 2, Plate VI, the Little Platte makes a bend, as is seen on the map. The section in the illustration crosses the stream twice, therefore, as shown at the pointse and d. We then ascend the hill B, which, from the exposures of bright-red sand- stones where the river had cut through, is conspicuous from a long dis- tanee. It is from the summit of this hill westward that section No. 11 is made. Section No. 11 Made in descending order : 1. Red sandstone shales outcropping on the summit of the hill dipping south 50° west, at an angle | OPT AWOUTISOS Pei I Peel ok pane dee 2. Very compact sandstones, generally of a mottled ) character, in rather thinlayers; general color, fomi@ky reds yey eis ce ste ipo 2 peat i ane ae . Very soft red sandstone, the first outcrop dipping as No. 2. Proceeding a very short distance we find that these sandstones form the center | of a small synelinal fold, the dip of the west- | ern side being to the northeast, at an angle | | of about 35° to 40°. We then have beds No. | | (Si) 40 feet. 2 and 1 the same as given above; below which) wea vie oh) 02 LAE. Se eae 4 Brighbiredishalesn asc sita eleye yeeros) ey 5 5. Coarse pink sandstone........-........-...- 10 feet. 6. Red sandstones and shales..........._.....- 80 feet. ~ 7. White sandstone with greenish tinge ........ 3 feet. 8. Very hard light-gray sandstones with bands of red shaly sandstone, varying from 4 inches to 3 Peet: fe U Leo US AE NE SSI EA eee speed 40 feet. 9. Hard gray sandstone, very similar to No. 8, with bands of soft red shales. The gray ’sand- stone is in bands from 6 inches to a foot... . 20 feet. 10. Brick-red sandstones with pinkish layers..... ol feet. 11. Bands of hard gray sandstone with interlami- nated shales, very fine and dark red. The lower band is about 2 feet thick, middle 6 ‘a imeches and top toobe saree eee eee ee 33 feet. GEOLOGY—SECTION NO. ll. 223 PEALE. | (12. Coarse light-red sandstone..............-..- 6 feet. 13. Maroon-colored sandstone, shales streaked with red. Near the top there are lghter-colored bands showing a gradual change toward ISTE PERS IS BBS WeGa Bes Fit GREASE 107 feet. EW ihihe Sain SLONGy nose be sei Pos aiedniand scrapes 13 feet. 15. Maroon-colored shales...<:--.-....---.----<-- 400 feet. 16. Pink sandstone with red bands...........--. 110 feet. 17. Fine maroon-colored shales..... Bee oe rie ck Sh 220 feet. 18. Light-maroon red sandstone shales...-..--... 108 feet. | 19. Dark-maroon red sandstone shales, very fine- oe GAP NNE eeaeed meals De eesena oeGendewerase 108 feet. | 20. Reddish maroon-colored sandstone.........-- 20 feet. 21. Gray micaceous sandstone with green spots, very closely resembling those found in bed 15 of section No. 10. I think this is a higher heel, INOW aoe deeds skboc sa eee de beads 15 feet. 22. Sandstones of a general greenish-gray color extending for about a quarter of a mile. | These are probably a few beds of interlami- l nated limestone. The beds were too much covered up, however, except to show that the sandstones are micaceous.......-. Ey 660iteet: h. 28. Dull reddish sandstone, rather light colored. This bed is on the summit of the bluffs at C Te TASH RO ae Be hoa Ae Ss eee Saar 16 feet. i. 24. Kime black and sray shales....-..-..--».:.-- 22 feet. j. 25. Yellowish-white sandstone....-.----.-------- 15 feet. i... 26. Brownish-red sandstone... -.....--...0ce0----= 26 feet. L. 27. Space reaching to the bottom of the hill, proba- bly filled with sandstone, but so covered with débris that the rocks are entirely concealed. 38 feet. All the beds given in this section are probably above those of section No. 11. They probably came up in the valley of the river between the points A and B, where the river turns, their softness allowing them to yield readily to the action of the water. My time was too limited to carry the section any farther either to the eastward or to the west. In the latter direction the beds continue down through the Carboniferous and Silurian. In following up the Little Platte we find exposures of red sandstone shales resting on limestones. I did not have time to make any section in the cafion, but in a subse- quent portion of the chapter will give a section made a little to the north of the creek. To the eastward, about five miles down the stream, I learn from the notes of Mr. Taggart, is a butte on the northeast side, west of which are exposures of red-beds, as shown in Fig. 7, Plate VI, at B. The dip here is 5° toward the northeast. Therefore, between this point and the bend of the stream where section No. 10 was made, is an anticlinal axis increasing from north to south, for there is no indi- cation of it due east of Fair Play. This is probably the only feld, there scarcely being room for more. The axisisabout north and south. The butte itself is volcanic, and the red-beds tipped up against a dip from 8° to 10° to the westward, as shown in the illustration. Crossing Four Mile Creek the dip is again east or northeast. Returning to the road, which keeps close to the low hills, a short distance below the point where sections Nos. 10 and 11 were made, is an outcrop of gray sand- stone, dipping a few degrees north of west. Still farther down the road 224 GEOLOGICAL SURVEY OF THE TERRITORIES. we pass over the upturned edges of the same sandstone now dipping in the opposite direction. Just above it is an outcrop of dark-blue lime- stone only a few feet in thickness, This is the same fold that we find in section No. 11, at the point B in Fig. 2, Plate VI. The axis has a: direction nearly north and south. The fold continues southward, and is shown again in a low hill above the salt-works at the point C in Fig. 7, Plate VI. It is not so decided here, however, and seems to be dying out. Fig. 7, Plate VI, represents a section running from the west side of the park eastward to the volcanic butte on the west side of Four Mile Creek. The following section is made on the bluff shown in _ Fig. 7 at the pointC. It is in ascending order on the line a b: Section No. 12. a. 1. The beds at the base of the bluff are entirely concealed for some distance, and then we have— 2. Red shaly sandstones breaking into very irregular pieces, 18 feet. 3. Light red shaly sandstones in bands of varying structure. The general color is of a brick red; some of the bands are very soft, and in fine lamine, while others are wery hard. The latter are very dark, almost brown. ‘The top of the bed is especially shaly, and has lighter-colored bands, 68 feet. 4, Rather coarse, grayish-white sandstone, 8 feet. 5. Reddish and greenish-gray sandstone, with interlaminated shales. Near the top there are very fine red shales, 45 feet. 6. Greenish-gray sandstone with bands of shale, 5 feet. 7. Brownish-red sandstone with interlaminated pink shales, 56 feet. 8. Coarse, light-pink sandstone, 12 feet. 9. Shaly sandstones, dark-red and very compact, at top lighter colored and more shaly below, 8 feet. 10. Conglomerate sandstone with irregular pebbles of limestone, 38 feet. 11. Coarse yellowish sandstone, 10 feet. 12. Coarse irregular sandstone, 10 feet. 13. Compact dark-red sandstone, with interlaminated shales, 125 feet.. 14. Soft light-red shaly sandstone, 15 feet. 15. Soft and rather fine gray sandstone shales, 15 feet. 16. Gray sandstone, 10 feet. 17. Brownish-red shales, 28 feet. 18. Light-red shales, 77 feet. 19. Coarse white sandstone. } 42 feet 20. Red shales ....-...2..- he ; This last bed crowns the bluff. Thedip of the beds is from 15° to 20°. They are, without doubt, of the same age as the beds of sections 10: and 11, which I thought were Permean. Near the salt-works we have three isolated buttes. The most southern, the one on the east of the salt-works, is trachytic, and is about 580 feet high. ‘The rock is of a liver- color, and jaspers are scattered over it in abundance. The base of the butte is covered up, but from the occurrence of gypsum in considerable quantity I take the rocks to be either of Cretaceous or Jurassic age. There are, however, no well-defined outcrops. To the east of this butte are two others, which Mr. Taggart determined to be volcanic, and of the same character. One of these buttes has two cone-like: projections. The plain around them is covered with an alkaline efflorescence. ‘This is especially seen in the valley in which the salt-works are situated. All the water in the streams in this region has an alkaline taste. At the works are two springs and two wells that have been sunk by the PEALE.] GEOLOGY—SECTION NO. 13. 225 company. The works, which have been quite extensive, are now entirely deserted. Crossing the stream to the butte north of the works, we discover at the base exposures of gray sandstones laminated, and containing gyp- sum. These sandstones seem to dip toward the north. In some places the gypsum seems to be interbedded, and in others occurs only in pockets. Ascending the butte, we find on the top trachyte, very much like that on the butte east of the works. The slope for some distance is covered with débris from this rock. It is probably a portion of an overflow that was once continuous toward Buffalo Peaks, for to the west, on a line between it and the peaks, is a third butte capped in the same manner, having gypsiferous beds at the base. The gypsum is very impure com- pared with that found in the hog-backs outside the mountains. Hast of the salt-works the line of the volcanic material has a direction toward the southwest, to the divide between South Park and the Arkansas River, where we shall speak of it again in a subsequent portion of this chapter. The range on the west side of the park, the Park range, is for the most part composed of sedimentary formations, which have been. thrown up, and dip toward the park. There are a number of extensive faults, the down-throw being always on the west side. This, however, will be rendered clear as we proceed. We will return to the northwest part of the park and commence the consideration of this range with Mount Lincoln, one of its highest peaks. Mount Lincoln and Mount Bross have both become widely known since the discovery on them of extensive deposits of silver-bearing galena. The mines here will be described in the mining report of Dr. Endlich. Mr. Taggart ascended Mount Lincoln from the town of Montgomery, and in speaking of the geological structure I will quote frequently from his notes. On the west side of the Platte River, below Montgomery, he made the following section : Section No. 18. Ascending order: 1. A light-colored quartzite, very much broken up. The weathered sur- face is greenish. The dip is 12° to north of east, 20 feet. 2. Gray crystalline limestone, conformable to No. 1. It has bands of laminated gray limestone, varying from a foot to a foot and a half each, 12 feet. 3. Limestone very much like that of No. 2, only darker in color, 15 feet. 4, Cherty limestone, 12 feet. Mount Lincoln is 14,121 feet above sea-level. It is capped with a trachytic rock, as seen in Fig. 5, Plate VI. This is probably the result of a flow from a dike; erosion has carried away so much material that it is isolated, and it resembles a bed that iscontemporary. At one point on the northeast spur of the mountain Mr. Taggart says he found a well-defined dike, about 10 feetin width, which seemed to extend through the bends. On the ridge running toward Mount Bross Mr. Taggart made the fol- lowing partial section : Section No. 14. 1. Soft and brittle carbonaceous shale, 6 feet. 2, Gray quartzite, with bands of a dark ferruginous quartzite one to two feet each, 75 feet. 3. Laminated micaceous sandstone, 2 feet. 16Gs 226 “GEOLOGICAL SURVEY OF THE TERRITORIES. 4, Gray crystalline limestone, with cross cleavage, breaking into small irregular pieces, 10 feet. 5. White quartzite, 3 feet. 6. Dark quartzite, 6 feet. 7. Gray limestone, with shaly bands and cross-cleavage, harder and lighter colored in the upper part of the bed, 20 feet. 8. White quartzite, gradually becoming darker until it is red, 80 feet. : 9. Very hard brownish limestone becoming laminated and dark-col- ored towards the top, 125 feet. 10. Light-colored quartzite, 50 feet. 11. Brown voleanic rock like that on the summit of Mount Lincoln, only darker in color. ‘¢ Below No. 11 is the limestone in which the mines are situated. After about 100 feet of this is a gray crystalline limestone, very hard and com- pact. This continues for several hundred feet. IJtis very irregular and much broken up, and is followed by a brown crystalline limestone, from which there is a great deal of débris.” Fig.5, Plate VI, represents a section through Mount Lincoln and Mount Bross, ina direction north and south. Mount Bross is nearly two miles south of Mount Lincoln. Between the two there is therefore a portion hollowed out, probably by glacial action. A semicircular ridge connects the two mountains, which were once probably continuous. On this ridge Mr. Ho!mes made the following section from below EDy . Gneiss. Quartzite. . Blue limestone. . Yellow limestone. . Limestone, (ore-bearing.) . Volcanic. it learn from Mr. Gardner and Mr. Holmes that the quartzites are faulted on Mount Lineoln. The quartzites are probably the equivalent of the Potsdam sandstone, and the limestones, which are mostly magne- sian, Should be referred to the Quebec group. In the latter, in Four Mile Creek Cafion, 1 found fossils that point toward such a conclusion. Fig. 6, Plate VI, is a section through Mount Bross trom west to east. The beds of the section will be found in Doctor Endlich’s report. Further notes in regard to Mount Lincoln will be found also in Doctor Hayden’s report. West of Mount Lincoln is Buckskin Mountain, which heads three streams, viz: the South Platte River, Buckskin Creek, and a branch of the Arkansas River. The first flows to the northeast, and turning to the east around Mount Lincoln, flows southeast. The second flows to the southeast into the South Platte, while the third flows to the northwest for about five or six miles, and then turns to the southwest and empties into the Arkansas. Above the town of Montgomery, between the South Plate and the Blue Rivers, on the main divide, is a pass called Hoosier Pass. Its elevation is 11,364. In regard to the- geology here, I refer again to the notes of Mr. Taggart, who : says: ‘The pass shows no outcrop, but is covered with granite boulders. Hast of it is a point, (A in Fig. 3, Plate VI,) the sides of which show no out: crop. The summit, which is flat, is covered with volcanic rock, and holes dug. by Bi ectorskshow the same material. There is a slope to the eastward. In the depression or saddle between this point and the next one, which is higher, the surface is covered with a debris of fine-grained gray granite. AS we ascend the higher summit we meet first with an outcrop of voleanic rock, and then higher up an outcrop of coarse con- Som Coho: PEALE.] ‘GEOLOGY—SECTION NO. 15. 997 glomeritic sandstone, which continues only a short distance, and then we have volcanic again, which continues over the summit until we again find on the opposite slope the sandstone. There is another rise. Then we have voleanic again, and then sandstone and vol- canie rock alternately for about half a mile, when, in a greater depression than the previous ones, we meet with, first, a coarse sand- stone, which becomes fine-grained, somewhat shaly toward the top. It is followed by a red micaceous laminated sandstone at the point B. These beds all dip east at an angle of abot 15°. They all seem to lie in the lap, as it were, of the volcanic rock which is pushed up through them. This is shown in the illustration Fig. 3, Plate VI. On tbe north- ern slope of one of the higher points (D) are fragments of a blue lime- stone. Above itis voleanic rock, but I could not determine the order of superposition. On the opposite side is a cliff-like wall about 6 feet high. The volcanic rock seemed to overlie it, and at one point there was a distinct dike about 2 feet in width, running through the lime- stone. The volcanic rock seems to have been thrust up and spread out: over the limestone. On the next slope are some coarse sandstones, dipping toward the west. From this point the ridge continues to rise gradually, and we have a long saddle-like depression connecting it with Silver Heels Mountain. On the side of the next high point, in addition to the beds already named, are— “1. Coarse sandstone. “62. Red shale sandstone. “3. Conglomerate. ‘4. Sandstone. * These beds lie against the side of the hill, and dip to the northeast.” The following section was made by Mr. Taggart on the ridge east of Mount Lincoln, on the east side of the South Platte River, and is in ascending order : Section No. 15. - 1. Voleanic rock, which seems to reach to the timber-line, although there are no distinct outcrops. The whole surface, however, is covered with fragments of the rock. 2, Coarse gray conglomeritic sandstone. On the summit of the next ridge we have— 3. Voleanic rock in blocks. Then— 4, Gray shaly sandstone, dipping to the 15°. Thisis about 3 feet thick. 5. Red shaly sandstone, about 6 feet. 6. Fine gray sandstone, with small gray quartz pebbles. 7, Volcanic rock in blocks as before. This exposure is on a higher point. : This section made by Mr. Taggart fills the gap between Mount Lin- coln and section No. 9, made across the park, the profile of which is shown in Fig. 1, Plate VI. This voleanic rock, to which reference has been frequently made, is mostly trachytic, and although in many places it has very much the appearance of being contemporary, I am of the opinion that it is all intrusive. We find that where it is contorma- ble to the sandstones and limestones the latter beds are always changed on both sides of the volcanic material. We have already seen this in the section made on Silver Heels, and we shall see it again in sections made farther south. There are also, as we shall see in Buckskin Gulch and in the cafion of Four-Mile Creek, a number of faults and dikes, in which everything points to the intrusive origin of the volcanic rock. , at an angle of about 228 GEOLOGICAL SURVEY OF THE TERRITORIES. This will be more clearly shown as we progress. First, we will speak of — Buckskin Gulch. Buckskin Creek, like all the streams heading in the Park range, has cut profoundly into the rocks, giving us an excellent opportunity to study the geological structure. As I have said before, the creek rises on the southeast side of Triaqua, or Buckskin Mountain, and flows toward the southeast, around the west side of Mount Bross, and empties into the South Platte. Passing through the deserted town, which was once a mining center, we soon find ourselves in the caiion. On the top of the wall-like bluff on either side, capping it, are quartzites and limestones dipping a little south of east, at an angle of about 199° to 15°. Approaching more closely, we see that the quartzites resting on the eranite are faulted. The appearance of the bluff-like wall is shown in Fg. . This is on the south side of the canon. The following section in ascending order is made on the line a f, in Fig. 3, Plate VII: Section No. 16. he 1. Granites, coarse and rose-colored. They extend to the bed of the creek covered with debris. 2. Very hard white quartzite, 20 to 30 feet. 3. Greenish volcanic rock, growing wider as we go toward the west and thinning out to the eastward, 15 feet. OF 4, White quartzite, 10 feet. 5. Greenish volcanic rock, terminating in a wedge-like point. It has split No. 4 from the bed above, (No. 6,) 12 feet. White quartzite, really a part of No. 4, 6 feet. Brownish snuff-colored quartzite, 2 feet. Light-colored quartzite, with dark bands,14 feet. Greenish volcanic rock, terminating in a wedge-like point, the point this time being to the westward, while before, in No. 5, -it was toward the east, 12 feet. ( 10. Dark-colored quartzites, 6 feet. | 11. Light-colored quartzites, 8 feet. | 12. Banded quartzite, in layers about a foot thick each, gray and Os rust-colored, 12 feet. | | l lenin =~ PLN 13. Light pinkish quartzite, 4 feet. 14, Dark reddish quartzite, 15 feet. 15. Banded quartzites, about 100 feet. These beds correspond to the quartzites on the side of Mount Lincoln, and are undoubtedly only their southern prolongation. As we go up the creek we find that there is a large fault, and that we again come to these beds dipping in the same direction. The line of this fault if pro- longed would pass to the west of Mount Lincoln near Triaqua Mountain. It probably extendsinto Mr. Marvine’s district. It also continues to the southward, where we shall refer to it again; the down-throw is to the west. In Mosquito Gulch, the next one south of Buckskin, the same beds occur with the same great fault, and with smaller local faults in the quartzites. Mr. Taggart made the following section on the south side oi the creek. It is made to the right of the fault (AB, CD, EF,) shown in Figs. 1, 2, and 3, Plate VIII. Section No. 17. ‘ 1. Reddish volcanic rock. 2. Dark quartzite, (reddish,) 3 feet. 3. Light quartzite, dipping 20° toward east, 8 feet. Plate 8. Figl = Fridt in Muesquito Gulch — Looking Seth OAT bt aren teen lala gett eZ UTA te CE —_ E i ) cl LG GF Fault wt Buckskin Gulch 5, de Het re eae Yin hic é ads! Plate 7. &.. sie Faults on Mosgetto Gitleh GEOLOGY—SECTION NO. 17. 229 PEALE. ] 4, Reddish volcanic rock, 12 feet. 5. Light quartzite banded with dark, 5 feet. 6. Gray quartzite. (@ 8. Greenish voleanic rock, 10 feet. Fie. 2 | 9. Light quartzite; unable to get thickness. Plate VII 10. Micaceous sandstone, 4 feet. 7 11. White quartzite, 8 feet. d. 12. Reddish voleanic rock, 15 feet. Fie. 1 e. 13. White quartzite opposite voleanie rock. Plate VIL it 14. Greenish voleanic rock, 8 feet. “Ca 15. Gray quartzite, 6 feet. 16. Micaceous sandstone, 4 feet. 17. Gray quartzite, with bands of brown sandstone, 20 feet. : 18. Pink sandstone, with bands of pink shales 2 to 6 inches thick, 3 feet. 19. Gray quartzitic sandstone, 40 feet. 20. Compact gray limestone, 15 feet. From Mr. Tageart’s notes I take the following: ‘ Below bed No. 2 there is gneiss on the same plane with a gray quartzite, f, in Fig. 3, Plate VIII. From diagram No. 2 to 3 the line of the fault is continuous. The fault is filled with volcanic rock, which can be very readily traced. The diagrams had to be made in sections. The line is not uniform. The voleanic rock at the bottom of diagram No. 2 is probably continu- ous with that at the top of No. 2, but there was so much débris that I was not able to ascertain definitely if it was or not.” The quartzites in Mosquito Gulch dip more nearly to the east than they do in Buckskin. The angle is about 15°. Going up creek we find the same fault we saw in Buckskin, and after passing the gneiss we find a small patch of quartzites, still dipping east but at aless angle. The gneiss has seams of voleanic rock. Then we have another fault, the line a@ Db in Fig. 1, Plate VII, which shows the appearance on the south side of Mosquito Creek. A short distance farther up, between the forks of the creek, is an isolated hill. (Fig. 2, Plate VII, shows this hill looking north.) The eastern end is gneiss, then follows vol- canic rock, and at the western end the same beds of quartzite outcrop that we saw at the mouth of the cafion. When we cross to the Arkati- sas side of the range we find them again, while between is a layer of very massive voleanic. rock. In addition to the quartzites on the Ar- kansas side are very dark, almost black, limestones, which probably belong to the Quebec group. These rocks are all highly metamor- phosed. The divide itself is composed of a volcanic rock with Silurian strata above. Between the divide, which has an elevation over 12,000 feet, and the hills to which we have just referred, and which are shown in the illustrations, there is a low pass, the direction of which is north and south. On the branches of Sacramento Creek—the next south of Mosquito—the same beds are lifted up on the granites. I did not go up the creek, but doubtless the same faults exist that are seen on the other streams. It was on Horseshoe or Four-Mile Creek that we were able to make the most complete sections. The following section was made from the mouth of the cafion of Four-Mile Creek westward to Horseshoe Mountain. It is in descending order: Section No. 18. a. 1. Brown metamorphosed sandstone, 3 feet. 230 GEOLOGICAL SURVEY OF THE TERRITORIES. > opob ~ 13) . Blue limestone, 30 feet. . Laminated limestone, bluish-gray, 10 feet. . Coarse brownish quartzite, 3 feet. Light-bluish limestone, with cross cleavage, and containing in places grades with quartz crystals, 20 feet. . Light erayish- -blue limestone, on weathered surfaces light gray; in the middle there is a band of blue limestone with white seams, 70 feet. . Blue limestone, the upper layers very hard and compact. The lower layers are fossiliferous, and contain on the weathered surface fragments of an Orthis like O. desmopleura, Meek, and Huomphatus, 50 feet. : . Light-gray magnesian limestones, 30 feet. . Quartzite,. 10 feet: - Bluish magnesian limestone, 4 feet. 5 \ViGiey hard, reddish quartzite, with interlaminated pier shales, the latter about 6 inches in width, and the cmaeatte varying from 8 inches to 2 feet, 10 feet. . Red and green hard shales, in fine laminee, and breaking into small pieces, 2 feet. . Reddish-brown quartzitic sandstones. About 3 feet from the bot- tom there is a layer 6 inches thick of red shale, with mud-marks in layers of a few inches each. The surfaces between the layers are brightest in color; 40 feet. . Fine brownish-gray sandstone shale, in lamin one-fourth of an inch thickness, 2 feet. . Brown quartzitie sandstone, in laminee from 2 to 4 inches thick; at the top the surfaces are coated with green, 30 feet. . Reddish quartzitic sandstone, 20 feet. . Dark-purplish quartzitic sandstone, containing near the top irregular layers of soit, dark-purple sandstone, with green glauconitic (?) grains, 15 feet. . Reddish quartzitic sandstone, somewhat irregular in structure, and containing layers of quartzite each a few inches in thickness, 15 feet. Quartzite, white below and pink above, in beds of 2 or 3 feet thick- ness, 15 feet. b. 20. Gneiss reaching to the bed of the creek. On the summit of the 21. d. 23. Volcanic rock, like 21. 24, , bill we have some of these beds folded in, as shown at the point kin Fig. 1, Plate 1X, between the gneiss "and the next bed. Volcanic rock, causing the great fault between the points k and ¢ in the section. In this voleanic rock there are included frag- ments of the stratified beds of the section given above. The thick- ness of the rock is about 300 feet. 2. Sandstones somewhat coarse and conglomeritic, dipping at an angle of about, 25° to 30°. This forms the cap of the hill, marked d in the illustration. At the bottom it appears to be about 300 _feet thick, and at the top must be nearly 1,000 feet. The rock is porphyritic, and the lower layer next to beds of No. 24 have a somewhat regular jointage at right angles to the dip. The color below is a gray, becoming rusty in places and lighter in color above. : Sandstones, for the most part coarse and conglomeritic, with inter- laminated black argillaceous shales, especially near the top; below we have a few bands of limestone, reaching 3 or 4 feey in thick- PLATE. XMM. — iia rt dd i rie a ith Nl os dad aN NM, ; Pe NOR ete ae Ban PLATE, XM, ZE ~S — a - = § Z > 7 \ my it — - ) ~ Z B = ane = = = — ee: 2 g F a2, We N ] 5 , ei - 4 — = = = = oN = : & ee Z ™ = ¢ 2 vy, y | j : - a \ - ea pet — - 7c 2 £ : ~*~ Fe ; : wend Lect eT te Lorse Sit Divide South Bark . e Grentte vertu hy Silurian Beas Fiewtt or Enlil Carborirerous heds capped hy Volcanic Rock, — cd Fold Carboniferous Beas Granite overlaid by Silurian Beds Horse Slee vie Fig: 1 Natural Section S. Side of 4 Mile Creek fi Wa Hp yt Wht of gn ghee Uf, i j,0! ji in ie yh ote ine y y, HSA ANGE fe Bh va / We J ji t 7 } / / Pm, Rei " Z 7 4 f nth bat win ' ih “ ry ut Lathe ' Fault Lireilt Mess of Tron Ore Kult Stluria Pocks with titabeded Treciiyte Grenites overtaid ly Siturtan Beds Continuation of Fig. 1 down Towa Gulch ces 007 a ei me “f- ig Np aves of va es hE: ay Eevee 5 = a 8 PEALF.] GEOLOGY—SECTION NO. 18. 231 ness. These sandstones extend from e to gin the illustration. At the point f there is a small fold. The general dip is to the east- ward, at an angle of from 10° to 20°. The angle is greater on the west side of the fold. The thickness of the sandstones is about 903 feet. 25. Black and greenish-gray sandstones, shales micaceous, 6 feet. 26. Sandstone, 51 feet. 27. Blue limestone, very dark, and weathering of a reddish brown color, 20 feet: 28. Sandstones, conglomeritic, generally of a gray color, about 600 to 800 feet. 29. Fine black shales, 6 feet. 30. Greenish-gray micaceous, sandstone-shale. The mica is silvery and especially distinct between the laminz. They become quartzitic above, 54 feet. 31. Bluish and brownish limestone, with interlaminated shales, 10 feet. 32.° Sandstone, 2 feet. 33. Limestone, 4 feet. o4. Fine black argillaceous shales, 9 feet. 35. Coarse grayish sandstone, 10 feet. 36. Limestones and shales, 6 feet. ' 37. Greenish-gray micaceous sandstones. Toward the top the beds be- come very coarse, 15 feet. 38. Limestones and bluish argillaceous shales with sandstones. The upper portion of the bed contains in blue shaly limestones fine specimens of Productus semireticularis, P. nebrascensis, Spirifer opimus, Productus prattenanus, and a Pleurotomaria,* 57 feet. ; 39. Black shaly limestones, in the lower part of which we find the fol- lowing fossils, Productus Spirifer, and fragments of Trilobites, 34 feet. 40. Quartzite sandstone laminated and micaceous, 15 feet. 41. Space covered with the débris of a porphyritic volcanic rock, 5 feet. 49. Shaly limestone, 3 feet. 43. Space covered with débris of volcanic rock, limestone, and sand- stone, 27 feet. 44, Porphyritic volcanic rock, about 10 to 20 feet. 45. Blue laminated limestone, 10 feet. 46. Quartzitic sandstone, lighter colored and laminated above general color, steel gray to brown, 6 feet. * PLEUROTOMARIA TAGGARTI, Meek. Shell attaining a large size, turbinate, very thin, slightly longer than wide; spire depressed, conical, a little shorter than the length of the aperture; volutions five to five and a half, flattened above to the slope of the spire, last one very prominent and angular around the middle, with the under side slightly convex and sloping inward nearly at right angles to the flattened slope of the upper side above the peripheral angle; suture merely linear; umbilical region but very slightly excavated and imper- torated ; aperture rather large, subquarate, with height and breadth apparently nearly equal; spiral band extremely narrow, occupying the peripheral angle of the body yolution, and passing around only about its own breadth above the suture on those of the spire ; surface nearly smooth, or showing only obscure lines of growth, with ap- parently megely the faintest possible traces of revolving striz. Height about 2.60 inches; breadth about 2.49 inches. In size and general appearance this fine species somewhat resembles P. missouriensis, (Trochus missouriensis, Swallow,) but it may be at once distinguished by having its body volution below the periphery longer than the height of the spire above ir, instead of flattened, as well as by wanting the distinct revolving lines of that species. The specific name is given in honor of William R. Taggart, esq., of Dr. Hayden’s survey, who discovered the type specimen. Zoo: GEOLOGICAL SURVEY OF THE TERRITORIES. 66. . Porphyritic voleanic rock, 20 feet. . Brownish-gray arenaceous limestone, 15 feet. . Blue laminated limestone, 15 feet. . Shales, 5 feet. . Porphyritie voleanic rock, 20 feet. . Blue laminated limestones, 6 feet. . Bluish-gray limestone, fossiliferous, 10 feet. . Volcanic rock, 8 feet. . Blue shaly limestone, 15 feet. . Sandstone, 10 feet. . Blue shaly limestone, 15 feet. . Sandstone, 6 feet. . Bluish black limestone, 5 feet. . Brownish quartzitic sandstone, 21 feet. . Bluish black limestone, 11 feet. 2. Sandstone, light colored and soft above, becoming darker and quartz- itic as we go down, 1( feet. . White laminated voleanie rock, 17 feet. . Indistinet outerops of a black shaly limestone, 12 feet. — . White quartzite of a rusty color on weathered surfaces. Just above it there are indications of bluish l!mestone, prebably a con- tinuation of bed 64, 75 feet. A very dark-blue limestone, weathering black crystalline, and con- taining nests of calcite distributed through it, 8 feet. h.67. Light colored laminated porphyritic volcanic rock, very similar to 68. 78. No. 63, about 10 to 20 feet. Dark bluish-black limestone, very irregular in structure, especially near the top; at top is pink on weathered surfaces, 60 feet. . Sandstone and limestone conglomerate, .10 feet. . Dark-blue limestone, 2 feet. . Rusty-brown quartzite, 2 feet. . Blue limestone, 50 feet. . Light-gray quartzite, 4 feet. : Light: blue limestone, with irregular cross-fracture weathering ote a lighter color, for the most part fine grained, becoming coarse in some places. In the upper part it becomes laminated ; and some- what darker. On weathered surfaces there are crinoidal frag- ments. Thickness estimated, 10-15 feet. . Light brownish quartzite, passing into sandstone near the top; a few feet from the bottom there is a layer, a few inches in thick- ness, of greenish sandstone, 20 feet. . Magnesian limestone, light colored, with seams of dolomite. The beds become darker from the bottom up; 50 feet. . Light-bluish magnesian limestone, weathering of a yellowish color, becoming siliceous as we go down, 15 feet. Brown quartzite, 10 feet. . Laminated sandstones,general color a pinkish gray; about half way down there is a layer of shales. The lamination is most distinct in the lower part of the bed, the lamine having a red coating, 15 feet. . Massive gray sandstone, 10 feet. . Pinkish-gray sandstone, laminated, laminz 1 to 3 inches in thickness, with green coatings between, 10 feet. . Light-gray laminated sandstone, somewhat shaly in places, laminz trom 1 to 3 inches ia thickness, 6 feet. Plate 10. LA ?, y) aig AL Sc Cuz} . a MEWS {Le > We IGS SHV, HOE OU LN al iy WU. Intrusion of Voltanic Rock ast of Horseshoe Mountain PEALE.] GEOLOGY—SECTION NO. 18. 233 83, Light reddish-gray sandstone, with red shaly bands. At the top there is about one foot of pink sandstone; 6 feet. 84, Sandstone with brown and red lines, general color reddish brown, dark below, 6 feet. 85. Yellowish-brown laminated sandstone, very hard and compact, almost quartzitic, breaking into lamin from one-eighth of an inch to 2 or 3 inches in thickness, 6 feet. 86. Gray sandstone, somewhat laminated at the top; weathering of a rusty brown; 20 feet. 87. Brown laminated sandstone, with green coating between the lamine, 2 feet. 88. Light brown sandstone, with bands of white quartzite varying in thickness from four inches to a foot; the thickest at the top; 6 feet. 89. Brown quartzitic sandstone in laminz of about 18 inches each, 6 feet. : 90. White quartzite, 4 feet. 91. Brown quartzitic sandstone, 2 feet. 92. White quartzite, (about 2 feet from the bottom there is a layer of brown sandstone 6 inches thick,) 5 feet. 93. Brown quartzitic sandstone, 2 feet. 94. White quartzite, 5 feet. 95. Brown quartzitic sandstone, 5 feet. 96. White quartzite, 20 feet. 97. Brown quartzite, 10 feet. 498. Granite, coarse, and rose-colored. This bed (98) reaches to the bottom of the cafion at the head of the creek under Horseshoe Mountain. The section from bed 1 to 20 is made on the line a b, Fig. 1., Plate [X. From bed 24 to bed 67, inclusive, it is made between the points e and h in the illustration ; while the remain- der of the section (68 to 98) is made on the line marked h7. In the top of bed 23 of the section given above we have fragments of the sandstone of No. 22 caught in the mass; and again we see the volcanic rock pene- trating the sandstones, and their interlaminated shales changing their character very much. Mr. Holmes sketched several of these intrusive masses, which are beautifully shown in Figs. 1 and 2, Plate X. The lower beds in the section given above dip at an angle of about 10 to 15 degrees. The quartzites and magnesian limestones in the last part of the section are the same that are given in the first part on the east side of the fault. It is a question whether or not the sandstones of No. 22 of this sec- tion (No. 18) are the same as No. 24, or whether they belong to a higher horizon, and have been merely separated by the intrusion of No. 23. I incline to the latter. The character of the sandstone in both places is similar, but in No. 24 there is very little difference between the top and the bottom layers. The difference is no greater than between No. 22 and the top of 24. If 22 is merely the continuation of 24 tolded, the ends of the two probably connect below the surface. The rock of No. 23 is pe- culiar. It is trachytic, and very highly siliceous. It is very white, and might, if seen alone and not very carefully examined, be mistaken for a highly-metamorphosed sandstone. A closer examination reveals the presence of crystals of feldspar. The large proportion of silica is due, perhaps, to the intrusion among the sandstones, from which it was, in great measure, derived. ‘As seen in the illustration, Plate IX, Fig. 1 atc, bed 22 dips about 30°, while No. 24, at ¢ in the illustration, dips about 15°. 234 GEOLOGICAL SURVEY OF THE TERRITORIES. At the head of Four-Mile Creek are two branches which head in Horseshoe Mountain. Each of these small streams heads in an amphi- theater, the center of which is granite, upon which rest the quartzite and limestone given in the section above at the lower part. They form an arch, as is seen in the illustration, and it is this that gives the name to the mountain. Between the two amphitheaters is a point which is capped in the same manner. The limestone and quartzite extend up on the divide, and it is in them that the silver-bearing galena is found. They are very much metamorphosed and somewhat broken up by veins of volcanic material. In Empire Gulch, which, with Iowa Gulch, heads directly opposite Four-Mile Creek, these beds outcrop again. lowa Gulch affords the best exposure, however. Fig. 2, Plate 1X, repre- sents the outline along the south side of Iowa Gulch, continuing the section that we made on Four-Mile Creek. We see, then, that at the head of the gulch another fault, as great as the one noticed on the divide as the head of Mosquito Creek. It is in fact a continuation of the same fault. A section through the hill, marked B in Fig. 2, Plate IX, is represented in Fig. 3, Plate XI, the figures corresponding with those in the following section: i Section A. . Volcanic, capping the hill. Black limestone, very much metamorphosed. Thin layer of quartzite. . Voleanie rock, columnar. Bed of quartzite. . Voleanic, columnar. . Quartzite. Voleanie, columnar. Fragment of quartzite bed. 10. Quartzite. 11. Volcanic, columnar. 12. Fragment of quartzite. The quartzite from a distance has a yellow color. The base of the hill is covered with débris, but underneath I think we would find gneiss. The beds of volcanic rock (which is a variety of trachyte) are beautifully columnar. Beds 7, 9, 10, and 12 are fragments that seem to have been caught in the flow of volcanic material. Figure 2, Plate XI, represents a section through a hill about half a mile west ot the hill B, on the north side of the creek, between the main creek and a small branch. Here we have the following section: SO GO IS OU Ge bo Section B. . Voleanie. Blackish limestone, very much metamorphosed. . Yellowish quartzite. . Volcanic, in fine columns. Gneiss. . Volcanic. > SUP Go bo The rest of the hill is covered to the base. In the gneiss, layer 5, there are seams of the volcanic rock. A section through the hill A, which is the same hill as A in Fig. 1, Plate LX, isshown in Fig. 1, Plate XI, corresponds to the following: _——————— -Plate 11. Sections Wel Flea ef Lott Gitlch ; Site oY Stren te roe, PEALE, GEOLOGY—SECTION NO. 19. 235 Section CO. . Voleanic, capping the hill. Black limestone, very much metamorphosed. Yellow quartzite. Volcanic, in columns. Quartzite. . Volcanic. . Quartzite. . Volcanic. . Quartzite. . Gueiss. In these three sections just given the bed marked No. 1 is the samein all. So is the bed of limestone marked No. 2 in all the sections. No. 3 of _the second section, (b,) in the third (c) has been split up into four beds, Nos. 3, 5,7, and 9. In the first, (a,) it has been split into six beds, viz, 3, 5, 7,9, 10, and 12. No. 4 of section (b) which is represented in the first (a) by Nos. 4, 6, 8, and 11. In the third section (c) the volcanic rock is much thicker, and is represented by Nos. 4, 6, and 8. It has thrown the fragments of quartzite, Nos. 5, 7, and 9, lower down. The bed, No. 10, corresponds with No. 5 of the second section. The hill marked C in the illustration (Fig. 2, Plate IX) is capped with volcanic, and below are sedimentary beds again which have dropped down. The center is gneissic. Still farther down the creek, at the point D, is another fault, and then a foid which is merely local in the quartzite between a and b. At the latter place there is a break again, and then the quartzites are almost, if not quite, horizontal. At E is another fault, and beyond the quartzites dip about 12°. It will be seen that in all these faults the down-throw is on the west side. In California Gulch, which is the one next north of Lowa, the rocks are more covered up, but there is probably the same condition of affairs as we see here. We have seen, then, that there are two main lines of faulting running north and south, which we have traced from - Mount Lincoln southward to Horseshoe Mountain, a distance of about ten or eleven miles. In Plate XII is represented a section made through stations 56 and 57, about ae miles south of Four-Mile Creek. The section is as follows: = SOMNBAPwWHH Section No. 19, made by Mr. Gardner. Conglomerate. . Soft white limestone. Gray limestone. . Nodular limestone. . Blue limestone. . Quartzite, white. . Schists with veins of granite. . Quartzite. . Nodular limestone and shales. 10. White quartzite. c. 11. Gneiss and schists. 12. Limestones. 13. Quartzite. d. 14. Gueiss. The faulting in the center of the diagram is evidently the second or western fault at Horseshoe. That is the one observed on the divide. DCHAIBOUPWHE 236 GEOLOGICAL SURVEY OF THE TERRITORIES. ~ The first one probably dies out to the southward of Station 45, or Sheep ete ome Mountain. The country slopes off in that direction, and from station 45. there is a long ridge on the east side of a branch of the Little Platte, which slopes toward the park. In following up the Little Platte to Weston’s Pass, I saw no indication of the first fault. The trend of the fault at the point ) in the illustration is about south 10° east. How much farther it extends to the southward I was unable to determine for want of time. The dip of the schists at the point d in the diagram is toward the east. They are of a rusty-red color, with micaceous layers in some places, and in others quartzitic beds with light-colored granites — below. These schists extend to the Arkansas River, and it is through them that the river cuts the caiion, to which I will refer further on. On leaving the mouth of the canon on Four-Mile Creek and going eastward, we find that all the underlying beds are covered. From a few indica- tions of voleanic rock, however, I am inclined to believe that there is a fault running toward the north, the line of which would pass east of Mount Lincoln. We have seen (section No. 16) that on the ridge east of Lincoln there is a line of voleanic rock. This probably represents a line of faulting. On looking at the map we see that there is an abrupt turn in the course of Four-Mile Creek directly on the prolongation of this line, the course for a short distance being in a line with that of the Platte west of the ridge where section No. 15 was made. In section No. 18, we have the Potsdam group in beds No. 11 to 19, a thickness of 119 feet. This is repeated again in beds 78 to 79. The estimated thickness here is greater, being 156 feet. In section No. 18, made by Mr. Taggart, in Mosquito Gulch, the thickness is 160 feet. In Buckskin Gulch it was estimated at over 200 feet in section No. 16. This last is probably exaggerated, as the upper bed in the section was estimated from a point some distance below it. The thickness of the Potsdam group along this range probably averages about 150 feet. The remainder of the Silurian layers will probably average about 200 feet in thickness. It is probably all referable to the Quebec group. The lower layers are so beyond doubt. A comparison with the same layers already treated of in the first chapter is given below: % e4 2 30 o oO aa -lae Locality. as go. or Cen Gg 99 aes lm Bae = os | qa ei a GlembBiyaste ss = elses ain = Siocinieye aerate nee eee eee oe eieniccinisrse seer 40 73 MromtiCre eles es ac Acs cee balsa sreelseaatelseieiaee pelea bstae elajaieerayers 60 to 80 | 100 to 150 Range between South Park and Arkansas Valley. ..-.....---.--| 150 200 There has, therefore, been an increase in thickness as we have come westward. The line between the Carboniferous beds and the Silurian is in all probability the bed No. 68 or 69 of section 18. The lower part of the Carboniferous contains a number of beds of limestone, with inter- laminated black shales, more or less argillaceous. In no case do these beds attain a great thickness, and between them are beds of. micaceous sandstones, which are laminated. Their general color is a greenish gray, with the mica especially noticeable between the laminz. ly bares te WAT Rumcal{ Yanaty, wWoasg2—asy ; | ‘OL 931d een GEOLOGY—SECTION NO. 20. 237 As we go up the limestones gradually thin out, and the sandstones be- come coarser and coarser, pointing to the existence of shallower waters during their deposition. I was unable to define the line between the Carboniferous and the beds that I consider to be of Permian age. Going south from Weston’s Pass we find that the range ends rather abruptly in Buffalo Peaks. South of this the divide between South Park and the Arkansas is comparatively low. Buffalo Peaks consist of two high conical points of about equal elevation, viz, 13,365 feet. Between the two there is a ridge bounding an amphitheater, which faces to the northeast. On the face of this we find, going from the top toward the base, the following beds: Section No. 20. a. 1. Trachyte, weathering very dark from the amount of iron it contains. There.are crystals of hornblende and sanidine. On fracturing the rock the matrix is seen to be light-colored. This is found on the western summit of the peak, and extends across along the ridge to the eastern summit. Below we have— b. 2. Trachyte. The upper part of the bed has a bluish color, which becomes red below. This is also hornblendic, and contains crys- tals of sanidine. The rock is more compact and finer-grained than that on the summit ; 100 feet. e. 3. Reddish breccia. The included masses are highly porphyritic, 100 feet. d. 4. Light gray tufa. I could not see the line between it and the one above. There are light-yellow pebbles in this rock. In the lower part there is a soft black layer, thin; 5 feet. é. 5. Columnar layer of very hard black rock, containing a large quantity of hornblende and obsidian. There are, also, a few included. pebbles. The columnar form is quite distinct in places; 50 feet. ( 6. Light tufacious rock, very sott, mostly of a white color, but pink in fe some places and yellow in others, 150 feet. *\ 7. Gray breccia,which reaches to the base of the peak as far as can { be seen; 200 feet. This section corresponds with Fig. 8, Plate VI. I was extremely sorry that I was unabJe to work to the eastward of the peak. Until that is done the opinions in regard to these rocks must be to a great extent conjectural. On the west side of the west cone, g in Fig. 8, Plate VI, resting on the granite, is a bed of white and rusty- looking quartzite, dipping toward the east at an angle of about 10°. Going toward the north we find above the quartzite, and dipping in the same direction, a bed of limestone very much changed. In one place there is a flinty layer, over which I found coatings of chalcedony. These beds are probably a continuation of those seen in Weston’s Pass at the pointe in Fig. 1, Plate XII. They seem to have been caught here by the voleanie rock. As we go south the beds continue uninterruptedly, as we shall see on Trout Creek. The rock on the summit of Buff- alo, although lighter in color, is very nearly like that found on the tops of the buttes near the salt-works. They are probably identiical, the differences being caused, perhaps, by the difference in length of time of cooling. In both places the trachyte is micaceous. The peaks are evidently a center of eruption, and the overflow was probably toward the southeast in the direction of the salt-works. Fig. representsan ideal section through the peaks from east to west, the dotted lines representing the planes of deposition of the various beds given in the section above. 238 GEOLOGICAL SURVEY OF THE TERRITORIES. There has been so much erosion, preceded by glacial action, that the greater part of the beds has been removed. That the section represents the actual condition of affairs is rendered the more probable by the fact — that Dr. Endlich found in his district just south of our line the same succession of beds at Promontory Point. Here the succession and. order of superposition was more clearly demonstrable. Trout Creek is the second large creek flowing into the Arkansas from the east below Buf- falo Peaks. Crossing the low divide southeast of the salt-works, we find exposures of black shales and conglomerate sandstones dipping a few degrees east of north, and inclining 35° to 40°. Below the black shales we have sandstones and green shales; then we have bluelimestone; then there is a space in which all the beds are covered up. The next outcrop is a gray limestone, below which there is a blue limestone. I was uuable to get the dip, but it is probably the same as we saw in the beds above. After leaving these outcrops we come into a small park, about five miles in length and over awmile in width. Itisa beautiful meadow-like park, in w hich the underlying beds are almost entirely con- cealed. At the upper end, however, I was able to make the following section : 5 Section No. 21. In descending order: . Light-reddish gray micaceous sandstone, 50 feet. . Blue limestone, 3 feet. Yellow sandstone shales, 13 feet. Light-red micaceous sandstone, 10 feet. . Hard reddish brown sandstone, 6 feet. * . Gray shales, 4 feet. . Red shaly sandstones, 6 feet. . Fine bluish shale, 5 feet. . Yellowish-brown sandstone, 3 feet. 10. Bluish shales, 6 feet. 11. Red shales, 9 feet. 12. Brown and red shaly sandstone, 13 feet. These beds all dip toward the northeast at an angle of 40°. They correspond closely to the limestones and sandstones” seen in sections Nos, 10 and 11, and to those east of Fair Play below the red beds, and which I have’ already referred to the Permian. Farther down the creek we find outcrops of greenish micaceous sandstone. These beds are laminated, and between we have fine black shales. The dip is still in the same direction. Below these are blue limestones, and still farther gray limestone. These beds are undoubtedly Carbon- iferous, and a closer search than I had the time to make would doubtless reveal fossils in some of the layers. At the lower end of the park the creek has cut its way through the beds at right angles to the strike, and the beds stand on either side as a high wall, dipping northeast at an angle of 15°. Resting immediately on the granite there is a bed of quartzite. Above this there is a bed of dark- gray limestone, about 200 feet in thickness. Next follows 10 to 20 feet of brown quartzite and then limestone. Above this the beds are cov- ered until we reach the Carboniferous layers already referred to. The quartzite and limestone resting on the granite are evidently the direct prolongation of the beds noticed west of Buffalo Peaks. Farther south and southeast, in Dr. Endlich’s district, these beds are more distinctly shown, and will be fully treated of by him. Trout Creek, for the rest ofits course, flows through granitic rocks. About two or three miles below MAD OP Cob) PEALE.] GEOLOGY—ARKANSAS RIVER. Bag the park we find on the east several high hills of trachyte. There is a small branch coming in here which seems to form the boundary between the trachyte and the granite. This is a portion of the same eruptive material seen east of the salt-works, of which it is the continuation southward. I shall reserve the consideration of the Arkansas Valley to the next chapter. CHAPTER IIL. ARKANSAS VALLEY—EAGLE RIVER—SAWATCH RANGE. The Arkansas River, in our district, has a course a few degrees east of south. On the east side we have the Park range, separating the valley from South Park, while on the west is the Sawateh, or main range of the Rocky Mountains, forming the continental divide. It has here, perhaps, its culmination. The range tothe southward of Mount Bowles falls off, as it also does north of the mountain of the Holy Cross, which is the last peak in the range in this direction. Before reaching this point the water-divide sweeps around the head of the Arkansas to the eastward. In the Sawatch range we have first Mount Bowles, rising 14,106 feet above sea-level. About twelve miles farther north is Mount Harvard, having an elevation of 14,208 feet. The next high point meas- ured was La Plata Mount, which is eleven miles northeast of Harvard: its height is 14,126 feet. Grizzly Peak, at the head of Lake Creek, is about seven miles from La Plata, and a little north of east from it. Its elevation is 13,786 feet. Six miles east of north from La Platais Mount Elbert, named in honor of the governor of Colorado: its elevation is 14,150 feet. Six miles farther north is Massive Mountain, having an elevation of 14,192. North of Massive Mountain the range is comparatively low until we near the mountain of the Holy Cross, when it rises again. The elevation of the Holy Cross is 13,478: it is about eighteen miles north of Massive Mountain. Beyond it, the range dies out, and we have Eagle River sweeping around to reach the Grand River. As we have seen in the latter part of the last chapter, Trout Creek flows through granitic rocks, which continue to the valley of the Arkansas and are the pro- longation of those seen west of Buffalo Peaks. The granite is gen- erally coarse and of a reddish color, with seams of white quartz. The bedding is probably the same as we saw at the peaks, that is, to the north- east. The eruptive rock that is seen near the head of the creek extends to the southward and southeast, and will be fully treated of in Dr. End- lich’s report. I did not go farther down the Arkansas Valley than oppo- site the mouth of Trout Creek. Here we have a beautiful broad valley, with streams coming in from either side, and cutting deep terraces in the deposits of drift. There isa gradual slope from either side to the fTiver. The main part of the valley lies on the west side, and it is here that the terraces are most conspicuous. The valley is park-like, and is ‘about six miles wide: it extends southward into Dr. Endlich’s district. I found nothing but drift as far as I had time to examine the deposits. I was unable to determine whether the drift is of glacial origin or not. It is probable, however, that it is, for in the cafions in the range far- ther north we have abundant evidence of glacial action. Below the mouth of Trout Creek, Dr. Hayden, in 1869, found Tertiary beds. He refers to them as follows :* “On the west side of the Arkan- * Report, 1869, page 177. 240 GEOLOGICAL SURVEY OF THE TERRITORIES. sas Valley the recent Tertiary beds run up to and overlap the margins of the mountains. They are composed mostly of fine sands, arenaceous clays, and pudding-stones, cream-colored arenaceous clays, and rusty yellow marls, fine sand predominating. These beds weather into pecu- liar architectural forms, somewhat like the ‘ Bad Lands of Dakota.’ In- deed they are very nearly the same as the Santa I’é marls, and were _ doubtless contemporaneous, and dip at the same angle, three to five degrees a little west of north. The tops of the hills have all been planed down as if smoothed by a roller. I have called this group the Arkansas Marls.” ; Above this valley the river is in a canon, or rather a canon-like valley, until we get above Twin Lakes, when we have another valley reaching almost to the head of the stream. It is about sixteen to twenty miles in length, and about ten miles in width at the lower end. The whole valley, as far as could be determined, is underlaid by granite. At the lower end, back of Weston’s ranch, in the terraces, there are modern Tertiary deposits, soft conglomerate sandstones. The whole valley is terraced, especially on the eastern side. These terraces are covered with drift, no under-lying beds being exposed until we get to the lower end of the valley. On almost ali the streams coming into the Arkansas from the west above the lower valley we have morainal benches. Be- tween the two broad valleys mentioned above, the river flows through a monoclinal rift in the granites and schists, the eastern side of the canon remaining intact, while the west is somewhat broken down by the streams coming from the mountain on that side. The caiion is plainly one of erosion, and in some places is from 1,000 to 1,500 feet in depth. The bed of the stream is strewn with enormous boulders, in some of which there are pot-holes. The river while in the cafion falls at the rate of about 60 feet to the mile. The first large creek coming in from the mountains above the mouth of the canon is Pine Creek. ‘There are along this creek well-defined lateral moraines. I did not, however, go up the creek, but waited until I reached La Plata, which is much larger, being about fourteen miles in length. The valley is about half a mile in width, with beautiful meadows in the lower portion through which the stream gracefully winds. On either side bordering this meadow-like valley are two morainal benches extending from the edge of the mount- ains to the river, a distance of about 800 to 1,000 feet in height; they are at the edge of the mountains, gradually falling off as we approached the river. I could find no evidence of any terminal moraine. The southern bench is well timbered on top with pines and aspens, while the sides of both are overgrown with sage-brush. Entering the cation, which is cut profoundly into the granites, and is quite picturesque, we find that the rocks scattered over the bottom are rounded and polished. There were very few evidences of striation and groovings on the rocks on the sides, and these were all very indistinct. In the center of the cation the stream has cut a deep, narrow, secondary cafion in the granites, some 50 feet below the general level of the valley, which once formed the floor over which the glacier passed. The next creek to the north is Lake Creek, which is by far the most extensive branch of the Arkansas; it is about sixteen miles in length, and flows almost due east, one branch draining the country between La Plata Mountain and Grizzly Peak, while another branch, the North Fork, comes from the north, draining the country southwest of Massive Mountain. Before reaching the river, the creek passes through the Twin Lakes, two beautiful lakes, probably of glacial origin: they are separated by morainal material. There are moraines on both sides of the creek, as well asalong all the main branches, ing Ta, On SOs Teshstiney: Saisie? VAL. Set niin peal Plate 13. VolcviriC Pock, ti re EST Ryden api ne eye ans raul : Pale See) ahi i See persiay Laer at ct et seats the ca) lee Vee Sin wo Ay PAY eh thus, i a acct av bi; J ae eh LAT at a tegearerG lens 2i0%) f= is Ae MP via. piety t ov, De imiaad Pont winst: UB! Re MURR ery eae se Mei. he Navi Mog Ritts ae | ot af Coke Pat (eames te Oe Orn ‘Wess f mah ans Okteyh © the ways Ke ops Le Ren re Sy 7 “PT 91d PEALE.] GEOLOGY—LA PLATA MOUNTAIN. 241 which are somewhat concealed in many places by the timber. The granites in the cafion are beautifully polished, and rounded even more noticeably than in the cafion of La Plata Creek. The rock exposed in these cafions is granitic—a granitic porphyry of a light color, with erys- tals of feldspar, (orthoclase,) rather large and conspicuous, in a fine- grained matrix: on weathered surfaces the crystals are of a purplish color. On La Plata Mountain Dr. Hayden found evidence of volcanic intru- sion. Ata pointin the cation below the junction of the North Fork there are also evidences of a trachytic dike. Following up the creek that rises immediately west of La Plata Mountain, and ascending the ridge opposite, we find trachyte. The western slope of the ridge is covered with débris, which weathers of a bright red color. The exposures are limited. We find an obsidian rock, which seems to rest on the granite: above this there is a gray layer; then a light-colored trachyte; and the summit of the hill is capped with a quartzitic-looking layer, the weathered surfaces of which are bright crimson: from a distance this color is very noticeable. There is a similar spot at the head of a small creek rising southeast of Grizzly Mountain. ‘This was visited by Mr. Taggart, who reported as follows: ‘‘In Red Rock Pass we have first the quartzitic layer, the débris of which is bright red, and from which the pass takes its name. Above this, as we pass eastward along the ridge, we meet with varieties of trachyte. Over the first point, lying appar- ently on the surface, there is granite and mica schist; next trachyte, and again mica schist, having an easterly dip, and an inclination of about 30°. Then we have more volcanic rock, followed by a coarse con- glomeritic layer, somewhat like the quartzitic layer first mentioned. It contains pebbles of quartz. This continues for some distance, and is succeeded by a green schist, (chloritic?) Above this there is trachyte again. Finally, we meet with a fine-grained granitic rock which con- tinues for quite a distance, alternating with a volcanic breccia, above which we have an obsidian rock, which is porphyritic.” At the head of the other branch we find granites and schists, having a dip a little north of east. The schists are dark and micaceous, with seams of quartz. The bedding is quite distinct in places, inclining at an angle of 40° to 50°. In the smoothed rocks at’the head of the cation, we have abundant evi- dence of glacial action. On the north side of the creek, high up on the ridge separating it from the one next to the north, on which Mr. Taggart reported, there is a capping of trachyte in columns. The rock is of a reddish color, and at one point seems to have included a portion of a bed of gneiss, as shown at Db, in Fig. —, Plate XIII, aa, being the trachyte. Grizzly Peak, which was visited and ascended by several members of the party, was also found to be volcanic. The figure in Plate XIV represents a block of voleanic breccia from this peak. I was unable to follow the line of the eruptive rock so as to define it accurately. In going up the creek, about a mile and a half above the mouth of the North Fork, we first meet with it crossing the ereek in a direction south of east. The western line has a direction of about north 25° west, and south 25° east; on the north side it curves more to the westward, while I think that not very far southward the western line joins the eastern. The North Fork probably flows partly along the line of juncture, between the volcanic on the west and the gneiss on the east. The extent of the outflow will have to be deter- Mnined by closer investigation in the future; I do not think that it ex- 16GS58 242 GEOLOGICAL SURVEY OF THE TERRITORIES. tends very far to the north of Grizzly Peak. On Massive Mountain the rocks are mainly gneissic, with alternations of a porphyritic granite, or rather granitic porphyry, with seams in places of quartzite and a horn- blendic voleanic rock. The general dip seems to be toward the north- east. To the southwest of the peak the dip seems to be toward the north and northwest. At the head of Roaring Fork, opposite the head of the Gunnison, the dip is to the northwest, and the angle of inclination about 50°. Between the two there is a continuation of the eruptive rock of Griz- zly Peak, but to what extent I am unable to say. The gneiss is mostly dark aud micaceous, with alternating beds of coarse white granite, in layers from four to eight feet in thickness. The country ali about is very rough and rugged, making traveling very difficult. Between the head of the Arkansas and the head of Hagle River there is a low pass—Tennessee Pass—the elevation of which is 10,242 feet. The upper part of the river flows through granitic rocks, in which there are occasional dikes of volcanic rock. The river flows through a cafion for about three miles, when it emerges into a broad, open valley about four miles in length and three wide. Here the sedimentary beds again make their appearance, dipping a little north of east at an angle of 5° to 10° ~=Resting on the gneiss there are quartzites about 200 feet in thick- ness, above which there are limestones, succeeded by shales and brown- ish sandstones. Mr. Holmes obtained some fossils here—Spirifer, Pro- ductus, Crinoids, &e. On the western side of the creek we have the lower quartzites capping the granites—the continuation of the same beds on the eastern side of the valley. At the head of the valley a large branch comes in from the east. Toward the head of this creek there seems to be a slight change in the dip. The beds which before were horizontal, or nearly so,‘and having a dip on the main stream to the eastward or northeast, now are slightly inclined to the westward, influenced proba- bly by the Blue River range. On the west edge of that range I am in- clined to think there is a fault, the continuation of one of the faults west of Mount Lincoln. I hope to be able to study this region more closely next season, so that it may be determined. Just below the meadow, the creek enters a cafion, and the line of the sedimentary beds erosses the creek. The trail here leaves the branch coming from Tennessee Pass, and crosses to a large branch coming from the west. For about four miles of its course, it is parallel to the other stream, and on the low ridge between them capping the schists there is a layer of quartzite, and on the east side of the canon of the main branch we have all the layers from the Silurian upward at least to the Upper Carboniferous. At the mouth of the Western Fork, a high hill stands between it and the other fork, capped with the Silurian quartz- ites. Here the main river enters a deep and rough inaccessible cation. The trail keeps high up on the hills overlooking it. Sedimentary beds are shown on both sides. On the west are only the quartzites which I have referred to—the Potsdam group. On the eastern side, however, we have beds at least as far as the Permian, and if we could have gone far enough to the eastward I am satisfied I would have found the Triassic sandstones on top, and perhaps even the Jurassic layers. Mr. Holmes says that farther north, on Eagle River, not only is the Jurassie present, but also the Cretaceous. This was west of Mr. Marvine’s district, and will be the subject of future investigation. The creek rising just north and west of the Holy Cross Mountain, and flowing to the northeast into Hagle River, was once the seat of intense glacial action, and the valley now presents us with the most beautiful example of whatis on the Alps PEALE.] GEOLOGY—SECTION NO. 22. 243 known as Roches moutonnés that is perhaps to be seen anywhere in this country. These Roches moutonnés are immense rounded masses of rock scattered through the valley, and from a distance look like a large . flock of recumbent sheep. These rocks have all been polished by the glacier. In thisvalley are also groovings and striations; these strice and grooves have the same direction as the valley. On the eastern side of the valley of Eagle River we have high bluffs, from which I made the following section: i Section No. 22. In ascending order: 1, Gneiss. 2. White quartzite. 3, Fine-grained, rather compact sandstone in lamine, having Sieenie grains, (glauconitic?) 10 feet. 4, Sandstones somewhat like those of No. 3, but grayish-brown in color; ; the laminz have a greenish coating on which there are mud- . marks; 98 feet 6 inches. 5. Space probably filled with sandstone, 22 feet 8 inches. . 6. White quartzite, like No. 2, 4 feet 9 inches. 7. Space, in the upper portion of which there is an outcrop of a met- amorphosed conglomerate, seemingly made up of pieces of white quartzite and brown sandstone. The masses are irregularly shaped. ‘The lower part of the space is probably filled with sand- stone; 68 feet 4 inches. 8. Light-bluish limestones, weathering on the surface white and yel- low, non-fossiliferous. It isin bands of from 3 to 8 inches, and has a cross-fracture. At the top it is crystalline. Part of the lime- stone is probably magnesian; 219 feet 6 inches. 9. Very hard black flinty limestone, with fragments of fossils and pieces of pyrite, 273 feet 9 inches. 10. Space probably filled with limestone, 1,400 feet. 11, Laminated volcanic rock, 15 feet. 12. Blue limestone with fossils ; could not define rans above. 13. Space, lower part of which is probably filled with a continuation ot limestones of No. 12, and the upper part with gray micaceous sandstones and shales, 408 feet 2 inches. 14, Greenish-gray micaceous sandstones, conglomeritic in places, 352 feet. 15. White granular sandstone, with brown spots, 8 feet. 16. Brownish sandstone, 99 feet 8 inches. 17. Red sandstone, 11 feet 4 inches. 18. Soft greenish sandstone in fine layers, with a few hard bands each a few inches in thickness, 99 feet 3 inches. 19. Coarse white sandstone, with grains of quartz; becomes finer grained above, 71 feet 3 inches. 20. Red sandstone, 57 feet. The fossils in No. 9 are very indistinct, some resembling Spirizer or Spiriferina ; the layer is probably Carboniferous. InN o. 12, [found the following, identified by Professor Meek: Aviculopecten, Pleur ophorus, and Avicula or Bakevellia ; these indicate Carboniferous age for the layer. The section above (No.22) was made north of Roches moutonnés Creek, and could not be continued farther because the bluffs became perpen- dicular. Section No. 23 was made below the mouth of Roches mou- tonnés Creek, and completes section 22. 244 GEOLOGICAL SURVEY OF THE TERRITORIES. Section No. 28. Ascending order: 1. Light-red conglomerate sandstone alternating with fine-grained _ sandstone shales, The latter have a ereenish tinge, and are mi- eaceous, and are from a foot to 2 feet in thickness. The conglom- erate beds are about 24 feet thick. The upper beds of shales are darker in color and break into thin lamina, while the conglomerate becomes lighter-colored; while in the middle they are dark-red. Near the top there is a layer of green shales about 8 feet in thick- ness ; 201 feet. . Silvery-gray micaceous sandstone shales, breaking into thin lami- ne, 1 foot. . Coarse white sandstone, with grains of quartz and some decomposed feldspar. ‘This layer is the same as No. 19 in section 22; 3 feet. . Hine-grained sandstone—white; becoming pink in places, with two or three layers of gray micaceous shale, from two to four inches thickness each, 4 feet. . Brownish-red sandstone, somewhat conglomeritic in places, 30 feet, 10 inches. . Dark-red micaceous shaly sandstones, 6 feet S inches. . Red conglomeritic sandstone, 38 feet 8 inches. . White conglomeritic sandstone, 5 feet. . . Coarse white sandstone. Near the top there is a band of very hard fine-grained red sandstone. All the beds seem to be micaceous; more marked between the layers; 40 feet. 10. White and greenish-gray conglomerates and shales. First we have _ conglomerate and then green micaceous shales, with black ear- bonaceous layers; then conglomeritic layers, above which we have about 15 feet of hard sandstone, with interlaminated shales that are soft; then 5 feet of gray compact micaceous sandstone. Next _there are very soft greenish-gray micaceous shales for about 10 feet, followed by from 10 to 12 feet of alternate beds of shale and sandstone, (some of the latter conglomeritic,) varying from 2 to 4 feet in thicknéss. Above these we have first conglomerates, then shales, and last of all, conglomerates; 511 feet 7 inches. 11. Coarse-grained gray sandstone, very hard, with greenish spots, 4 WES” 12. Fine-grained reddish-brown sandstone, 27 feet 4 inches. 13. Coarse grayish sandstone, with interlaminated shales near the top; there is a layer of red sandstone, above which there is a con- glomerate layer ; 25 feet 1 inch. 14. Sandstone conglomerate below, with pebbles of quartz, 2 inches in diameter. This bed is the base of a bluff, and is about 10 feet thick. Above there are alternate beds of shale and coarse sand- stone. On top of all there is greenish micaceous sandstone; 252 feet. 15. Sandstone and shales, 251 feet 7 inches. 16. Sandstone conglomerate, 5 feet. 17. Shales, 20 feet. 18. Coarse sandstone and fine micaceous shales, 86 feet 10 inches. “ 19. Conglomeritic sandstone, 3 feet 9 inches. 20, Blackish micaccous shales, 3 3 feet 9 inches. 21. Light gray shales, with hard sandstone bands, 3 feet 9 inches. 22. Conglomerate and gray shales, 92 feet 9 inches. 23. Pink conglomeritic sandstones, 37 feet 5 inches. iS) or isa ee) oma cs PEALE.] GEOLOGY—SECTION No. 23. 245 24. Coarse white conglomerate, 27 feet 3 inches. 25. Greenish-gray micaceous sandstone shale, with hard sandstone bands; 45 feet 11 inches. 96. Very hard blue limestone, irregular in structure; brown on weathered surfaces. ‘This limestone has the same character as the limestone in the shaly sandstone in section No. 10; 10 feet. 27. Coarse gray sandstones with shales, 145 feet. 28. Massive sandstones of a greenish tinge. Mostly fine-grained and micaceous. Some beds are pebbly, and near the bottom there is from 6 to 8 feet of black shale with carbonaceous material. The upper part of the bluff on which these exposures are is conglom- eritic, where the color is darker than below; 205 feet 10 inches. 29. Rather coarse gray sandstones in these beds, weathering of a rusty color, fossiliferous; 342 feet 4 incbes. 30. Space reaching to the summit of the bill, and filled, in all peewee ity, with sandstones ; 500 feet. All the beds in this section have a dip toward the northeast, the angle of inclination varying from 10° to 25°. As we go down Eagle River, we find that the beds above gradually make their appearance, and that the dip becomes more and more toward the north, until the beds curve around the end of the range of which the mountain of the Holy Cross is the last high point. Going eastward from the mouth of Roche Moutonnés Creek the dip gradually decreases toward the Blue River range, where there is, as I already mentioned, no doubt a fault. There is also, I think, a very small synelinal feild between Eagle River and the Blue River range. In bed No. 29 of section No. 22 I found fossils which were submitted to Professor Lesquereux, who has found the following species : Calamites Suckovti, Brgt., Calamiies gigas, Brgt., Stigmaria fucoides: of the first he Says: “‘ This species is perhaps more abundant in the coal-measures ; but it ascends to the base of the Permian, where, in Europe at least, it has been found in plenty.” The same species, however, was associated with Calamites gigas, which, Professor Lesquereux says, is exclusively Permian, or has as yet never been found in the Carboniferous measures. Of Stigmaria fucoides he says: “It is a universal species of the coal-measures, also ascending, rarely however, to the Permian. I am inclined to con- sider it as Permian merely. by the lithological relations to the other specimens, but it is not possible to decide positively from this.” The latter specimens were found somewhat lower (a few feet) than the other specimens. The layer in which these specimens were found probably lies near the line between the Carboniferous and Permian formations. All below probably belongs to the Carboniferous. Two things are especially noticeable here, namely, the small amount of limestone when compared with the section made at Horseshoe, (section No. 18,) and again the presence of so much carbonaceous material in the shales and sandstones. We have seen in the section above that there are numer- ous black shaly layers, but besides there are also in the sandstones at various places patches of black carbonaceous material. When these layers were being deposited there must have been low, marshy ground bordering this part of the Sawatch range. This range must therefore have been partly above water, or at least not very far below the surface. There may have been oscillations of the surface. The sandstones at the upper portion of the bluff, those in the laiter part of the section, are very much like those below the first fault on Pour- Mile Creek, (No. 24 of section No. 18.) I think they are of the same age. Another season we may study these beds again, and above them I hope 246 GEOLOGICAL SURVEY OF THE TERRITORIES. to discover the limestones and interlaminated red shales that we found east of Fair Play, (No. 18 to 51 in section No. 9.) The Sawatch range is, therefore, probably a true anticlinal axis, the sedimentary beds on the east side, where the Arkansas Valley now is, having been removed and carried down the Arkansas to help in form: ing the plains. The beds spoken of in the last chapter as being faulted in the range on the west side of the park, are the remnants “of these beds that once extended uninterruptedly to the Sawatch range, form- ing the eastern side of the anticlinal. We have seen that the range dies out both toward the north and toward the south, its highes t por- tion being just opposite the park. Not only is the ev idence of the anticlinal shown at the northern end, but also on the south, as will be © seen in Dr. Endlich’s report. The western side will be treated of in the next chapter. The elevation of the park range, in which Mount Lin- coln and Buffalo Peaks are situated, probably took place in the Creta- ceous or early in the Eocene, times. It is probable, also, that at the same time the main range west of the Arkansas attained its greatest elevation. It was doubtless above water before this, the sedimentary beds dipping slightly from it toward the eastward. This may have re- sulted from a more gradual action, while the later elevation was due in part, at least, to voleanic action. Crossing the range at the head of Lake Creek, we descend on the west side to the waters of the Gunnison Rtiver, which at this point flows through a meadow-like park called Tay- lor Park. This park is bounded on “the west by gneissic rocks. The basis of the park is also granitic and gneissic, but it is for the most part covered with drift, probably all of glacial origin. All-the creeks com- ing into the Gunnison from the east, rising on the western slope of the Sawatch range, in the park, present evidence of glacial action. On Texas Creek, the second creek from the lower end of the park, there are well-marked lateral moraines, reaching from the edge of the mountains almost to the main river and gradually decreasing in height. Almost all the curves of these moraines correspond with those of the streams | upon which they are found. In the limited time which I had I found no evidence of terminal moraines. The main portion of the park lies on the east side of the Gunnison River, which keeps close along the edge of comparatively low granite or gneissic hills. Several outcrops of granite are found throughout the park, but’ they are mostly covered either with the glacial drift, or, close to the streams, by alluvium. The park has its greatest width at the southern portion, where it is about six miles wide. At the northern end, on some of the branches coming in from the northeast, volcanic material is seen, which is probably con- nected with that on Grizzly Peak and that in the pass at the head of Lake Creek. At the southwest corner of the park the Gunnison enters a Caiion in the granites. Dr. Endlich went through this cation, and for an account of it L refer to his report. East of the cation and south of Taylor Park, from which it is separated by a lowridge of granitic hills, is a Smaller park called Union Park. Here we found some men work- ing in the drift on the branches of a small creek and getting out a lit- tle gold. The two principal gulches are named Cotton and Lotus Gulches. Placer-mining was carried on here and in Taylor Park in 1860, but it was broken up by the Indians. Both Taylor and Union Parks are partially timbered, and in the valleys of the streams we have a growth of sage-brush, (artemisia.) The remainder of our district, in- eluding the Blk Mountains and the head-waters of Roaring Fork, I will reserve for the next chapter. PEALE. ] GEOLO GY—GUNNISON RIVER. 247 CHAPTER IV. GUNNISON RIVER—ELK MOUNTAINS—ROARING FORK. Leaving Taylor Park, we followed to its source one of the western branches of the Gunnison, which for the greater part of its course flows through gneissic rocks of the same character that we saw on the west side of the Gunnison, and of which they are really the continuation. The course of the stream is about northeast. Near the head of the ereek we found the first sedimentary beds we saw west of the Sawatch range, in an outcrop of blue limestone containing Zaphrentis and Spirifer. The Jayer in which the fossils occur is very dark in color, and has above it lighter-colored layers that are non-fossiliferous. The strike of these beds is north and south, and they incline about 10° to the west. As we follow them southward, the strike gradually turns toward the west- ward. A few miles south of this outcrop, between the Gunnison and the east branch of Taylor River, I ascended a high point, which I found capped with the same limestone. I named it the Triangle, from the shape of this capping, which was triangular. It seemed to be the center of these ridges, one running toward the west, one toward the north, and the third toward the south. Its height is 12,830 feet above sea-level. Beneath the limestones are quartzites, probably Silurian. The northern side of the hill heads a small creek that joins the east branch of Taylor’s Creek just above adeep gorge. The course of this small creek is at first toward the north, and then west. It rises in an amphitheater, recalling the form of Horseshoe Mountain. The dip here was toward the north- west, there being a sharp turn to the west in the strike, which on the ridge to the north is almost north and south. As we follow the ridge to the west, however, the strike turns still more until its direction is north of west. Toward the south, however, the dip is toward the southwest, -and on the next high point, about a mile south of the Triangle, on the northern part, it is toward the northeast. Between these points, there- fore, there is a fold. The more southern point was visited by Dr. End- lich, and I learn from him that the summit is granitic, and that the beds dip away from it in all directions. I think that the cause of this folding is to be referred to eruptive agencies, the evidence of which is to be seen in the dikes that we find to the westward, and which will be referred to presently. Before this disturbing element was present the general dip was probably to the westward. The east branch of Taylor Creek cuts its way at right angles to the strike across the strata that continue west from the Triangle, and flows through a narrow rocky gorge, in which I made the following section from north to south: . Volcanic. ) . Limestone. . Quartzite. . Volcanic. . Sandstone and conglomerate. 6. Limestone. The first layers are very indistinct, but. enough is seen to show that the dip is toward the northeast in Nos. 2 and 3. The first layer is a dark-green porphyritic rock, probably trachytic. Nos.2 and 3 are prob- ably Silurian, and are the direct prolongation of some of the lower lay- ers seen on the Triangle. We see that the dip has changed. LayerNo. 4isa highly siliceous rock (Rhyolite?) and is in lamine which inchne ore Whe 248 GEOLOGICAL SURVEY OF THE TERRITORIES. - toward the southwest. There are included fragments of limestone and quartzite noticed in some places. ‘The last bed of limestone has a dip to the southwest and inclines at an angle of 65°. About two miles farther down the river, at the mouth of Dead Man’s Gulch, the dip is again north, or a few degrees west of north. At the head of Dead Man’s Gulch, and between Taylor River and Cement Creek, are two points, stations 72 and 73, which we ascended from the vailey of Hast River. On the ridge running southwest from Station 72, which is the most western of the two, the first rocks met with were sandstones dipping north 75° west, beneath which was a bed of limestone dipping in the same direction at an angle of from 5° to 10°. We next passed over a saddle, beyond which are irregular structured pink and white mottled limestone, containing fragments of fossils like those we found in the Silurian layers in Glen Hyrie, east of the foot-hills. Indeed, the beds bear avery close resemblance to them, and I have but little doubt that they are of the same age. The dip here is north 55° west, at an angle of from 5° to 10°. Below the beds just given are quartzites which rest on reddish granites. On the station itself we have limestones and quartz- ites, in too much confusion, however, to make a very complete section. The lowest exposure is a coarse quartzite, above which is a band of very black limestone, flinty and containing pebbles. This is from 3 to 4 feet thick. Next is a light yellowish limestone, followed by a brownish-gray limestone, above which we find dark-blue limestone. The dip on the western side is toward the northwest. This changes toward the north until it becomes northeast: the angle is 10°. There is also a change to the south and southeast, where we find the dip to be south and south- west, and the angle 25°. The station has a broad top, and is 11,862 feet above the sea-level. On the ridge, between stations 72 and 73, the dip of the beds is east of north, and the angle 15° to 20°. We have here about 60 feet of white limestone and then about 40 feet of reddish quartz- itie sandstone. These beds, 1 think, belong immediately below those seen on station 72 and above those seen on the ridge we ascended. At Station 73 we have the following beds; ; 1. Irregular spotted limestone; general color, gray. The lower portion iS very compact, and full of purple spots. It contains, also, on the weathered surfaces, fragments of crinoidal stems and corals. The thickness I estimated at about 20 feet. . Soft white-purple spotted sandstone, about 8 or 10 feet in thickness. — a Light-gray limestone ; very compact,especially above, where itis also somewhat laminated ; and on the suriace, weathers red. Its thick- ness is from 30 to 40 feet. 4, Irregular gray limestone, with large flint nodules and pebbles. This is at the upper part of the bed; could not get at the lower part, which is probably like that I have referred to above on the first ridge we ascended; could not give the thickness. : 5. Quartzites and sandstone ; thickness not estimated. 6. Mica schist; below this ped we have rose-colored granites. These are the extension of the granites in the cafion of the Gunnison River, and they reach to the westward and southwest toward Hast River to a line of trachyte rock. Along the creek heading under Station 73 and flowing into Hast River, flere were several exposures showing the bedding of the granite very ‘distinctly. The dip was about north 75° west, at an rangle of from 55° to 60°. I'rom the station we could over- look ‘the cation of Taylor River, which seems to be very rugged and cut through the granites. From Station 93 the line of outcrop of the ® © PEALE.) GEOLOGY—EAST RIVER VALLEY. 249 sedimentary beds curves in toward the northward, and then back toward the south, and crossing Taylor River turns gradually toward the north around the granite point just south of the Triangle. The general dip seems to be north aud northwest. This entire region is one of great interest, and to be worked up in detail will require some time. I can hope to give only the most prominent features. Below the mouth of Cement Creek, East River flows through a beauti- ful broad valley, in which it has eut well-defined terraces in the drift. On the south side, some distance back from the river, are two mount- ains, with mesa-like summits. They were not visited, but they are un- doubtedly capped with, trachyte, as is a high hill on the north side, which was ascended by Mr. Taggart. It is composed of a light purplish trachyte. This rock extends to the eastward and southeastward, and is probably continuous into Dr. Endlich’s district. Above Cement Creek the river flows through a broad open valley, on either side of which the Cretaceous formations are exposed. I will refer to this valley again further on. Leaving the valley of Kast River we proceeded up Cement Creek, which, near the mouth, is in a caiion. The first exposure of sedimentary rocks is on the west side, near the mouth of the cafion. Here are white and rusty sandstones, dipping about south 65° west, inclination 15°. These sandstones probably belong to the Cretaceous No.1. Farther up the creek we meet with dark and rusty-colored lime- stones, which I think are unconformable to the sandstones near the mouth, and belong to a lower horizon. They will have to be traced to the westward before their exact relation can be determined. The dip here is about north 45° west. Farther up stream, below these lime- stones, are beds of quartzite, which rest immediately on the granite. They are probably Potsdam. The dip gradually changes, and about three-quarters of a mile up the canon it is north 5° west, angle 10°. The course of the creek here is south of west. The caiion for about two miles has a comparatively wide valley, reaching to the base of cliffs on either side. Above this point the cafion narrows, and the trail has to make a wide detour. Just at the point where the creek enters this canon the sedimentary beds cross almost at right angles to the course of the stream. The dip here is about north 15° east, angle 20°. Above this point the creek flows through a beautiful grassy valley, in which all the beds are covered until we have gone about a mile and a half up Stream, when we come to beds of conglomerate with a red matrix con- taining pebbles of limestone and granite. These seem to be somewhere near the line between the Carboniferous and the Triassic (?) formations. Above it are red sandstones. The dip of these beds is, toward the northeast angle, 10° to 15°. Leaving Cement Creek at this point, we crossed to Deadman’s Gulch, striking one of the northern branches, down which we proceeded until we reached a fork coming in from the north. At the head of this the red-beds are tipped up, and dip about south 35° west, at an angle of 25°. This change in the dip seems to have been caused by the upheaval of a. high point to the eastward, which I took to be voleanic, judging from the débris in the creek heading under it. I was unable to visit it for want of time. Foilowing up the main Taylor Creek we find that the layers we saw crossing the east branch of the creek still continue, the strike being toward the north- west. One of the dikes (Layer No. 4 in the section) is very prominent. Whether the other continues or not I could not determine. At the head of the creek there is some confusion in the beds. On the west side of the ereek are high bluffs of limestone, on top of which there is a conglomerate sandstone. Below these beds, near the creek, is’a Dao). GEOLOGICAL SURVEY OF THE TERRITORIES. series of limestone shales. These beds on top of the bluff dip toward the northeast at an angle of 60° to 65°. Following the ridge to the north we find that a red feldspathic granite makes its appearance, and on a high rounded hill on the east side of the amphitheater at the head of the creek, resting on the granite,is a bed of white quartzite, above which are bluish and yellow limestones. These beds, I take it, are Silurian. At the southwest side of the hill the dip is toward the south- west. This gradually changes to the west, and finally to the northwest as we go toward the northern end of the hill, where the angle of inclina- tion is 25°. Between these beds and those referred to above as appear- ing in the cliffs farther down the creek, there seems to be a break. In the amphitheater are beds of blue limestone with shales, all dipping toward the southwest; but when we ascend the ridge on the northern side we find limestones, black shales, and sandstones, followed by thick beds of limestone, all dipping to the northeast. When we ascend Italian Mountain the confusion of these beds is explained. The mount- ain is named from the colors it shows at a distance, red, white, and green, the Italian national colors. The white is due to the granite, of which the peak is mainly composed; the red is seen on the weathered surface of included beds of quartzite, and the green is seen in the grassy Slopes on the eastern side of the mountain. Its elevation is 13,255 feet. The peak is made up in part of a light-gray granite, which I consider to be eruption, and rusty quartzites very much metamorphosed. These quartzites in places stand on end, and in others dip southwest and north- east, at angles from 80° to 85°. Between some of the beds are long narrow seams of the granite. This is beautifully shown in the accom- panying illustration made by Mr. Holmes, Fig. This shows, also, how the quartzite has been broken up by the gran- ite. The illustration shows the northern face of the peak. On the west side there is a fault of about 400 feet in the quartzite. This fault ex- tends to the northwest, and I shall refer to itagain. Hxtending from the peak toward the southeast is a line of eruptive granite gradually thinning out. Close to Italian Mountain is a high point at the com- mencement of a ridge, which forms the western side of the amphithea- ter heading Taylor Creek. Italian is the most eastern high peak in the Elk Mountains. The name Elk Mountains is applied to the mass of mountains between the Gunnison River and the waters of the Roaring Fork of Grand River. The trend: of the range, at first, is almost at right angles to the trend of the Sawatch range. Afterward, however, it turns to the northwest. The nucleus of the range is composed of erup- tive granite, of which that on Italian Mountain is apart. The general trend of this granite, which shows itself in three island-like patches, entirely isolated from each other, is northwest and southeast. ‘This is also indicated by the courses of the principal streams. The course of Roaring Fork and its branches is toward the northwest, while Hast River flows to the southeast, its course being parallel to that of Roar- ing Fork, although it flows in exactly the opposite direction. To the north of Italian Peak, between it and the divide between the Gunnison and Roaring Fork, there are remnants of the sedimentary beds. To the west we have a grand view from the summit. The island of erup- tion is distinctly shown, the white or light-gray color of the granite be- ing contrasted with the dark colors of the older stratified rocks, above which are the bright-red sandstones of Triassic age, and resting on them, in a few isolated places, patches of lighter-colored beds that are of Jurassic and Cretaceous age. The sedimentary beds are beautifully Ber) GEOLOGY—SECTION NO. 24. ~ 201 shown dipping away from the granite nucleus. They are lifted high up, and form some of the most prominent peaks in the range, the stratifi- eation of the rocks giving the mountains a peculiar architectural form. The pyramidal form is frequent. Southeast of the peak I made the fol- lowing section in ascending order: Section No. 24. 1. From the pass at the head of a small western branch of Taylor River we have a space reaching about 400 feet up the hill, in which the beds are covered. Occasional outcrops indicate that this space is filled with red sandstones below, above which there are lime- stones, with interlaminated shales and conglomerates. Above we have as follows: . Hard gray laminated sandstone, becoming coarse near the top; dip 50° ; 50 feet. - Conglomerate ; pebbles of blue limestcne and granite, from 1 to4 inches in diameter, in a coarse red sandy matrix, 30 feet. . Brownish red sandstone, 20 feet. , . Space probably filled with continuation of No. 4, 20 feet. . Dark, compact, grayish-blue limestone, fossiliferous, with veins of cal- cite, becoming laminated, and somewhat laminated as we go up, 12 feet. - . Yellowish-gray standstone, becoming conglomeritic above, with peb- bles of limestone and granite. The dip here is about 40°; 4 feet. . Coarse yellow sandstone, 5 feet. . Fine yellowish sandstone, in lamine of about 4 of an inch. The: lower layers have a reddish tinge, while pose above become more gray ; 3 feet. : Sandstone shales; some of the layers are conglomeritic, aia peb- bles of limestone. Below they are gray, in the middle red, and above yellow; 60 feet. . Compact blue limestone, very dark and laminated below, lighter- colored above, and fossiliferous, 4 feet. . Bluish-gray calcareous shales, 8 feet. . Yellowish sandstones, somewhat shaly, graduating toward the top into fine caleareous shales, 50 feet. . Bluish calcareous shales, 3 feet. . Snuff-colored sandstone, loose textured and porous, 4 feet. . Bluish-gray calcareous shales, 25 feet. . Blue laminated limestone, weathering light gray, 5 feet. . Sandstone, weathering dark yellow, with interlaminated soft gray sandy shales, all calcareous, in layers from 1 to 2 feet thickness, 50 feet. . Coarse reddish yellow sandstone, followed by an alternation of sand- stones and shales, 60 to 70 feet. . Purplish-red sandstone, 5 feet. . Reddish-yellow sandstone, 30 feet. . Yellow sandstune, 10 feet. . Reddish sandstone, 5 feet. . Sandstones and shales, 30 feet. . Space probably filled with sandstone, 70 feet. . Blue laminated sandstone, 25 feet. . Gray sandstone, 8 feet. . Coarse reddish sandstone, becoming gray toward the top, 65 feet. | . Blue fossiliferous limestone, 5 feet. — 2d2 GEOLOGICAL SURVEY OF AisS), SURE DCO LANES. 30. Micaceous sandstones and shales, general color gray and yellowish, greenish gray at top, 40 to 50 feet. 31. Greenish-gray micaceous sandstones, all laminated and having a few thin beds of limestone near the top. They extend a distance of about a quarter of a mile, dipping at an angle of about 30° toward the northeast. 32. Hard irregular black limestone, 10 feet. 33. Rusty- brown quartzetic sandstone. 34. Brown crystalline limestone. I was unable to get the thickness of these last two beds, as they were somewhat confused by the presence of the eruptive granite, which rises here toward the high point just south of Italian Mountain. The ' quartzites seen on the peak evidently belong to this section, of which they are probably the lower portion, for the upper layers here are really the older or lower if the beds were in their proper position. There has been a complete inversion. The dip on the top of the ridge is about north 40° to 50° east. In bed No. 1 of the section No. 24, some distance below No. 2, ina red limestone, I found a specimen of Loxonemia. It was below the con- glomerates given in the upper part of the bed. It is probably Carbon- iferous. In layer No. 61 found Productus muricatus, Spirifer, and other indistinct fossils. In No. 11 there was a profusion; among the speci- mens collected, Professor Meek has identified Productus muricatus, N. & P.; Athyris ’subtilita, Hall; Rhynchonella osagensis, Swallow; Henv- pr onites er assus, M. &. H. ; : Ter ebratula bovidens, and Retzia punctulifera. In No. 29 I found some fragments, among which Productus muricatus was identified. Descending to Cement Creek we again find conglomerates and red sandstones, dipping to the southwest, the angle being only a few de- grees, (5° to 8°.) As we go up creek ‘this i increases gradually until the beds are suddenly turned up and stand almost on end. Mr. Holmes tells me that beyond this point the beds dip to the northeast. There is therefore running across the creek here a line of fracture, the direction of which is northwest and southeast. On the south side of this line, which is probably connected with the fault in the quartzites on Italian Mountain, fragments of the Cretaceous beds cap the hill. Some distance down the creeks, as we have already seen, the dip is toward the north- east, inclining from 6° to 15°. Between the two points there must be a synclinal fold, the axis of which crosses Cement Creek with a direc- tion a little west of north. From Cement Creek we crossed to the head of a small branch -of Cascade Creek, the east branch of Hast River. This small creek rises on the broad divide, and has cut its way through the red sandstones, which are capped here with lighter-colored beds, probably of Jurassicage. Below the red sandstones are thick beds of red conglomerates like those seen on Cement Creek. The dip is west, or perhaps, in some places, a few degrees south of west. For a short distance the creek flows through a grassy valley, that gradually deepens until it ends on the edge of steep blufts, over which the creek flows to join the main stream, which is about 600 feet lower down. From here we have an excellent view down the river. The cation walls of Cascade Creek are bright-red sandstones and conglomerates, in which, on the west side near the forks of the two streams, is a broad trachytie dike. (abin Plate XV.) It is about 50 feet wide, and crosses the creek. Its direction is about south 65° west. The dip of the beds seems to have been but little affected by the dike. As we go down stream the dip Plate 15. oe ye Hy RT a is yi Drke on Cascatte Creer aD Dye Of Lrachyte cece Red Sandstones ard Cong oie es PEALE. | GEOLOGY—SECTION NO. 25. 253 becomes more and more toward the south, and we pass over red sand- . stones and conglomerates. The matrix of these conglomerates is a coarse red sand,in which are large pebbles of limestone. The angle of the dip to the southwest is 25°. This is at a point about a mile below the forks. A number of beautiful falls and cascades diversify the course of the stream. Below these the dip changes, and it is toward the north and northeast. This corresponds exactly with what we saw on Cement Creek.. Below, in all probability the Silurian layers may be discovered, although I did not have time enough here to HES them. About two miles below the forks a large creek comes in from the “northwest. ltrises under Castle Peak, and I will have occasion to refer to it again when I speak of the peak. From its mouth a broad open valley reaches almost, without interruption, to East River. Just above the mouth, on the east side, in the bed of the creek, there is an outcrop of quartzite, below which are shales. On the west side, reaching up for 400 or 590 feet, are limestones, above which we find the red-beds. I cannot say with certainty of what.age these beds are, but they are probably Carboniferous. A little less than a mile farther down the stream we find, on the west side, outcrops of Cretaceous rocks, consist- ing mainly of calcareous clay shales, with interlaminated limestones. In one of the upper layers I discovered fossils agreeing with those I found east of the mountains in bed No. 2 of section No.1. The bed has the same characteristics, including even the bituminous odor on fracture. Above we find from 25 to 30 feet of rough conglomeritic sandstone of a rusty yellow color; next are thick beds of laminated limestone. All these beds Gip toward the northeast. Crowning the hill are red-beds. There is, 1 think, a fault running through here. Its direction is proba. bly northwest and southeast. It extends across Teocalli Creek also. Here, however, the beds are very much confused, seeming to have been crushed together. Mr. Holmes has made a very excellent drawing of the appearance of the beds on the west side of Teocalli Creek in Plate XVI. The following section was made here, the letters being the same as those in the illustration: Section No. 25. { 1. Conglomerate of large limestone pebbles in a red | i Thickness not 4 J siliceous matrix. : accurately ~ \ 2, Fine red sandstone shales, with bands containing taken; about i nodules. 10 to 15 feet. p. {2 Very hard, compact, dark and blue, almost black, limestone; & = inches to 1 foot. ( 4. Purplish blue limestone; weathering, reddish on surfaces; 1 to 2 | feet. C 25. Steel-gray quartzitic sandstone, 1 foot. 6. Soft light-gray calcareous sandstone, shaly below, 10 feet. I? ved: sandstone, fi ne grained, and somewhat soft, 2 feet. p} 8. Gray sandstone, 3 feet. i 9. Soft gray sandstone shale, 2 feet. me 10. Conglomerate, 6 feet. Below the beds given in this section we have as follows: ited sandstones, 10 feet. White sandstones, 15 feet. Red sandstone, 8 feet. Mottled sandstone shales, 10 feet. 254 GEOLOGICAL SURVEY OF THE TERRITORIES. The beds are very irregular in structure, and alsoin color. Thesamebed may be conglomeritic at one place, and then gradually become fine, while - the color will shade from a deep red into white or gray. Not only are _the beds crushed together, but they are also broken, as seen in the illus- tration. The line F G represents the fracture. As we go up Teocalli Creek the beds on the west side dip at first at a very small angle, not more than 5°, to the south or southwest. Farther up it is 45°, and this soon increases to 80°. As we go west, along the ridge, we find that the beds are completely turned over past the vertical. Mr. Taggart was on ‘the ridge, and found Carboniferous fossils in beds that were inverted. On the east side of the creek is a high pyramidal mountain, (Teocalli,) which I ascended. Its height is 13,098 feet, and it rises over 3,000 feet above the bed of the creek. The stratification of the rocks composing it is almost horizontal, and they have weathered into curious forms. On the east and south is a series of enormous steps, while the north face presents castellated forms. The rocks are all very much metamorphosed, and are of a dark maroon-red color. At the base on the southern side Mr. Taggart found the following beds from below upward : . Yellow conglomerate. : . Purplish limestone. . Yellow limestone and purple shales. . Purple shaly limestone. . Compact brownish-red sandstone. . Green cherty limestone. . Purple sandstone. . Sandstones. These beds all dip about north 45° east, at an angle of about 55°. He was unable to carry the section any higher, as the slopes were grassed over. The mountain stands on the southern edge of the eruptive island of which Italian Mountain is the most eastern high point. Here it is rather narrow; but to the east, south of Castle Peak, it widens, as it also does around White Rock Mountain, to the northwest of which it again narrows and ends, the sedimentary beds not having been broken through. The following section was made from the summit of Teocalli Mountain in descending order : ANAOEONH Section No. 26 1. Very fine textured laminated sandstone, generally of a maroon color, although grayish in some places. They have been very much changed. Thickness about 350 feet. . Yellowish metamorphosed sandstone, 50 feet. . Metamorphosed conglomerate gray matrix, with large purplish peb- bles, 50 feet. . Fine-grained sandstone streaked with lines and spots; general color reddish maroon; about 50 feet. . Gray con glomérate, with interstratified purplish and gray sandstones, 200 feet. Gray sandstone and conglomerate, 150 feet. Coarse-grained light gray sandstone, greenish in places, 6 to 8 feet. . Sandstone conglomerate, 5 feet. .. Light-grayish brown sandstone, 50 feet . Coarse greenish variegated sandstone, 20 feet. . Space probably filled with sandstones that are yellow, judging from the débris ; 55 feet. Ol HB _ Goh i HODNAND D Wi908L Ha TIA)9 we Aaya pun Lrazpnog ‘OT 129" 1g maui aa tees SAS PEALE.] GEOLOGY—SECTION NO. 26. 255 12. Yellowish-white limestone. The upper part grades into a sandstone, and has small crystals of pyrites. Below the bed has an irregular cross-fracture, and is white on the weathered surfaces. Thickness about 20 feet. 13. Rusty yellow quartzite with seams of eruptive rock running through it, which has disturbed the beds very much. The angle ot the dip here is about 50°, and seemsto be toward the east ornorth of east. Thickness is about 50 feet, 14. Hruptive granite reaching to the creek, a distance of about 600 feet. These beds on Teocalli Mountain seem to have been broken off from those on the west side of the creek, and carried up past them. Crossing the ridge from Teocalli Creek to Dike Creek, coming from Castle Peak, we followed the stream up to the foot of the peak. At the foot of Teo- calli on the east side, there seems to be a dip to the west or southwest. This gradually changes to the south and southeast, toward the east. The exposures are all of reddish sandstones and coarse conglomerates. As we go up, the strike of the sedimentary beds crosses the creek and has a direction a little north of east, probably joining the line of out- crop of the beds northwest of Italian Mountain. After leaving this line the valley is underlaid by eruptive granite, and near the head of the creek resting on this granite on the summits of the ridges on either side are the sedimentary formations, forming a semicirele around the head of the creek. At the head of the amphitheater thus formed is Castle Peak, a high, black-looking peak, in shape somewhat resembling Teo- calli, Itis not so regular, however, the outline being very rough and ragged. It is on the north side of the eruptive island, and is composed mostly of sandstones that are very much changed and intersected with dikes. We ascended the mountain, but the weather wasso stormy that I did not attempt to make any section. The summit is 13,930 feet.above sea-level, and about 2,400 feet above the head of the creek. While on the top we were almost cgnstantly surrounded by clouds, and it was only occasionally and for a very short time that we were able to see any of the surrounding country. From the peak eastward the general strike is a little south of east, with an irregular outline until we reach the head of the Gunnison River, when it turns to the north, and seemingly follows a branch of Roaring Fork, which fiows to the northward. On the summit is a very hard metamorphosed laminated sandstone, gener- ally of a somber reddish-brown color, streaked in places with green. Next below is a very handsome sandstone conglomerate, and then a yellowish sandstone, all metamorphosed. Below these we have an alter- nation of red sandstones and conglomerates until we reach the base of the mountain. The beds are all more or less changed and intersected by dikes, which sometimes cut across the strata, and again lie between different layers. The dip is nearly due north, and the angle of inclina- tion on the ridge below the summit is from 5° to 10°. It is difficult without closer study to determiné with exactness to what age these rocks should be referred. Ithink it probable, however, at that the base we have the Potsdam sandstone or quartzite, and above the Silurian, the Carboniferous, and Permian rocks. Those on the summit are proba- ably Permian. Perhaps Permo-carboniferous would be the best term to apply to them. White Rock Mountain is at the head of Teocalli Creek. To the south the sedimentary beds are overturned, the strike being northwest and southeast and the dip to the northeast. On the north the dip is to the north and northeast. To the west the sedimentary beds extend across the granite. There is, however, a break, although the granite does not appear through them. Before reaching this point 256 GEOLOGICAL SURVEY OF THE TERRITORIES. the beds that were turned over beyond the vertical have resumed their original position, and the ends have been dragged in, as shown in Fig, 1, Plate XVIII, which represents a section made west of White Rock. The peak is made up of eruptive granite, and is 13,671 feet high. Near the base I found micaceous hematite coating the surfaces of the granite débris in radiating crystals. The rock near the summit is very much broken up, rendering the ascent of the peak a little dangerous in places. North of the peak the summits of the ridges are capped with sediment- ary beds, dipping north and northeast. All the mountains in this mass have conspicuous amphitheaters, in which there are snow-banks aud small lakes, the latter generally frozen. Returning to the mouth of Teocalli Creek, we find ourselves in the broad valley of Hast River. East River flows through Cretaceous rocks. Below the month of Slate River, the largest western branch, are several beautiful terraces. The Cretaceous area extends southward into Dr. Endlich’s district. Below the mouth of Slate River, on the west side of Hast River, beyond the valley, the Cretaceous rocks are covered by an overflow of trachyte. As we come around from Teccalli Creek to Hast River, the most strik- ing points are “‘ Crested Butte” and “Gothic Butte,” which stand be- tween Hast River and Slate River. They are both isolated, and rise considerably higher than the surrounding country. Both are sur- rounded with cretaceous shales. Crested Butte is the more southern of the two, and is 11,838 feet in height. It is composed of eruptive gran- ite, similar to that on Italian Mountain and White Rock. Between the two buttes there is an exposure of trachyte, which is probably continu- ous with a band that is seen in Gothic Butte. The latter is six miles © from Crested Butte. It was visited by Doctor Hayden, and to his report the reader is referred for the details of its structure. The summitis trachytie. Whether this is only a capping or not I cannot say positively. I am inclined to think, however, that it is not merely a capping, but that its relation to the surrounding beds is as shown in Fig. 1, Plate XVII, at a. Below the trachyte that is seen on the summit are cretaceous shales on the side of the butte, and below a second layer of trachyte. On the oppo- site side of the valley Mr. Holmes found in the shales of No. 2 Creta- ceous, a bed of trachytic rock. This extendsfor some miles. I think that this mass is intrusive, and is connected with the trachyte of the butte. Mr. Holmes was unable to determine the line of junction between it and the beds above. I but little doubt that the shales just above will be found changed to a greater or less degree near the tra- chyte. I have before referred to the inversion of the beds on the north- east side of Hast River. These inverted beds are seen in Fig. —, Plate XVII, the Silurian being on top. The lower beds are all cretaceous. At the head of a small branch of Hast River we have blufis of these beds dipping to the northeast about north 55° east, at an angle of 20° to 25°, First are about 100 feet of very thinly laminated black shales, non-fossiliferous. Next are yellowish sandstones and shales for about 150 or 200 feet. In the lower part of these shales fragments of stems and leaves are found. I saw also some poor specimens of inoceramus. Above we have black shales. How far they extend I was unable to determine, the slope being grassed over. On another smali creek, the one seen to the right of a hill, the first exposure is a bed of white lime- stone shown at /, Plate XVII. Below, or rather above, as the beds are inverted at the point e, Mr. Holmes found fossils of No. 3 Creta- ceous. This bed of limestone is, therefore, probably the same white bed that is seen in the Cretaceous all along the foot-hills on the edge of the plains. It is bed No. 1 in section No. 1, and No. 44 in section No. Plate XVII. View up Hast River Ter ernie any ving peng re aig nap nests eas wo chrmenarernaieauemena: went ate em oy ae | PEALE.] GEOLOGY—ELK MOUNTAINS. D567 8. Then there is a space reaching to the bed d, which seems to be filled entirely with black shales. At dis a bed of white sandstone, quartzitic in places. It is beyond doubt the No. 1 Cretaceous. Above it are variegated shaly beds. The colors are very bright. ‘They are green, purple, yellow, and white. They extend for 300 or 400 feet, and are succeeded by red-beds which extend for nearly 1,000 feet, grading into maroon-colored beds, beyond which are yellow beds, probably rep- resenting the Silurian. Above No. 1 Cretaceous, therefore, is a com- plete series from the top of the Jurassic to the base of the Silurian. At gq the eruptive granite is seen. The illustration shows also how the beds farther along, at a, are in their natural position. On the other side of the valley, just above Crested Butte, the dip is northeast, and at this point, therefore, Hast River flows in the axis of a synclinal fold. At the base of Gothic Butte the dip is the same as on the opposite side of the valley, viz, toward the southwest. On Slate River the rocks are all Cretaceous, and there are some very fine terraces cut into these rocks. The general dip, I think, is to the northeast or east. I hope to be able to visit this region again in continuing the work westward, and to be able then to determine some points that are as yet somewhat indefinite. The Elk Mountain region is sufficient of itself to furnish several years’ work. Slate River formed the western limit of our work for the season at this point, although more to the north we worked considerably farther to the westward. Fig. 1, Plate XVIII, represents a section (partly ideal) through Gothic Mountain and across the granitic area west of White House Mountain. It is an interesting fact that the beds from J to c are right side up, while a short distance down the river they are inverted, as seen in Plate XVII, and also on Rock Creek, as shown in Fig. 2, Plate XVIII. It is opposite Gothic Mountain that they are in the normal position. It is fair, then, to infer that the presence of Gothic Mountain has something to do with it. Hither the force of upheaval of the latter counteracted the force of elevation of the main range, or the egress of the trachyte acted as a relief to the latter force. The two elevations were probably contemporaneous, at least in part. The erup- tion of Gothic Mountain must have occurred at the same time that the inversion of the beds, beth below and above it, took place. At the same time the beds were compressed laterally, and the fold between ¢ and d was formed. As we look down East River, from Bellevue Mountain, we have a fine view of these beds. They are so folded between c and d as to form a semi-quaquaversal. As shown in the illustration, subse- quent erosion has broken the connection between the beds, and a little beyond the point where the section was made the granite is seen in the center. At e, on the north side of the granite area, the sedimentary beds are seen dipping toward the northeast. It is probable that the mass of granite shown at /f and the trachyte forming Gothic Mountain are connected. It would be interesting if we could trace the trachyte down to that connection and learn whether or not there is a gradual transition into the granite. The Elk Mountains present many complex problems, and it will require years of close and arduous work to master all the geological details. Each stream, with all the numerous small branches, will have to be followed to the very source, and almost every ridge and prominent peak will have to be ascended before all the ob- scure points can be made clear. Itis one of the most interesting regions in the entire extent of the Rocky Mountains. Iam confident, however, the observations made during the season of 1873 are in the main cor- rect, and although much remains yet to be done, future observers will find but few errors in the work already recorded. Tus - 258 GEOLOGICAL SURVEY OF THE TERRITORIES. Above Gothic Mountain, at the head of East River and on the same side of the stream, is Slate Mountain, which is so called from the fact that it is largely composed of bluish and black slates, all of which belong to - the Cretaceous formations. At the base of the mountain the quartzite of No. 1 outerops. These shales prevail toward the southwest beyond Slate River. Bellevue Mountain, opposite Slate Mountain, at the head of East River, is similar in its composition. ~~ From East River we crossed to the head of Rock Creek, which is one of the branches of Roaring Fork, which it joins below Sopris Peak. On Rock Creek, as £ have already intimated, and as is shown in Fig. 2, Plate X VIII, the beds are again inverted on the east side. The in- vestigation of the beds on the west side of the creek had to be left to the explorations of the next season. The following. section was made a few miles down the ereek on the * east side, and is in ascending order: Section No. 27. . 1. Reaching from the bed of the creek up on the hill to the point a in Fig. 2, Plate X VIII, we have a space filled in with limestones and black shales. ‘ a. 2. Very hard calcareous black shales, breaking into laminz of about 4 of an inch, 44 feet 7 inches. 3. Argillaceous sandstone, in places very shaly, 89 feet 2 inches. 4, White limestone, breaking into laminie of about Es of an inch thick- ness, 6 feet. 5. Black argillaceous shales, with interlaminated bands of hard sand- stone, 191 feet 3 inches. 6. Space of which the upper part is probably filled with white sand- stone, and the lower part with alternate sandstones and black shales, 213 feet. 7. Bluish shaly sandstone, weathering a rusty color, 8 feet. 8. Rusty-colored calcareous sandstone, 15 feet 10 inches. 9. Bluish calcareous sandstone, 4 feet. 10. Yellowish-white sandstone, containing impressions of leaves, 82 feet 8 inches. 11. Shaly sandstones, with included hard bands. The lower beds are rusty-colored and the upper ones greenish ; 45 feet 4 inches. — 12. Space, the bottom of which is probably filled with shales, gradu- ally giving place to limestone. At the top there is an outcrop of blue limestone, having near the upper part a band of green- ish shale; 90 feet 3 inches. 15. Yellowish sandstone, with bands of light blue limestone, 36 feet 3 inches. 14, Space, in which, as indicated, there are coarse red and gray lam- inated sandstones, 83 feet 10 inches. 15. Coarse purplish conglomeritic sandstone, 12 feet. 16. Rather fine variegated sandstone. 17. Purplish conglomerate. c. 18. Space filled with alternations of conglomerates and fine shaly sandstones. The general color is a reddish-streaked and mot- tled with gray. On top there are some white beds, which, from a distance, I took to be limestones. LT was unable to determine the exact thickness of the last beds in the section. Above them, there is but little doubt that all the beds reach- ing through the Carboniferous to the base of the Silurian are present. Plate 18. a - ae rrr } | | | | | i | | : | | | Sections throu gh. Elk Mts: | # t Aye Hh ei) GEOLOGY—ELK MOUNTAINS. 259 The dip is north 55° east. At the point a in the illustration (Fig. 2, Plate XVIII) the angle of inclination is 58°, and at b it is 35°. Bed No. 10, in section No. 27, is the sandstone of “ No. 1 Cretaceous,” and in it Mr. Holmes found some fragments of leaves, none, however, very dis- tinct, but sufficient with the lithological characters to identify the bed. The layers just above should probably be referred to the Jurassic. Fig. 2, Plate XVIII, represents a section through the Elk Mountains, near the head of Rock Creek. Section No. 27 was made from «a to 6¢. Whether the line of junction is exactly as represented at d in the illustration cannot be definitely determined until the line shall have been ° followed throughout its entire extent. The granite probably makes its appearance in places along this line. On theeastern branch of Rock Creek, (é in the figure,) which isin part of its course parallel to the main stream, the Carboniferous or Permo-carboniferous rocks are exposed at the bottom of the valley, and above them forming high bluff-like walis. On either” side are red sandstones dipping north of east. Near its head the main branch of Rock Creek turns to the west, and at this point the dip of the rocks also changes. On the north and west side of the creek, in the space formed by this turn, is Treasury Mountain, so named from the discovery there of lodes of silver-bearing galena. At the south end of the mountain the dip of the sedimentary beds is south 5° east, and the angle of inclination is about 12°. As we follow the course of the creek the dip changes as the creek turns, and on the west side it is east of north. Treasury Mountain is composed mainly of cretaceous shales. Toward the west there are gypsiferous beds. At the point where the mines are situated, black shales containing quantities of Inocerami pre- vail. They are all very much changed, probably by the intrusion of the metaliferous lodes. The latter are described in Dr. Endlich’s report.* On the east side of the creek, opposite Treasury Mountain, there seems to be either: a bend or a fault in the Cretaceous beds; the shales at one place appear to dip toward the northwest. I did not . have time to investigate it, but I am inclined to regard it as merely local. As we go down the creek the beds on the right side still oceupy an inverted position. Just below the mouth of the eastern branch of Rock Creek, it enters a deep cation. Here, below the cretaceous rocks, the older formations, at least as far asthe Carboniferous, are exposed, as shown at a in Fig. 3, Plate XVIII. Following the eastern branch we cross the No. 1 Cretaceous twice. The second time the bed is inverted, as above it we find the older beds, which are beautifully shown on both sides of the deep gorge-like valley, dipping toward the northeast at an angle of from 50° to 60°. There is, therefore, probably a fold as indi- cated in the illustration. In the cretaceous rocks at b a dike outcrops. The creek, as it flows over the edges of the cretaceous rocks, does so in a series of beautiful cascades and falls. As we continue up creek the beds become more and more horizontal, until they dip slightly in the op- posite direction, and we have a synclinal fold, the center of which is filled with Silurian beds, for the layers are still inverted. The ends of _ these beds, c, seem to have been broken away from those which outcrop in the cafion at a. _ We next cross a comparatively narrow belt of gran- * Mr. R. A. Kirker, who is interested in the mines here, showed me specimens of coal found inthis region. He did not disclose the locality, and Idid not discover it. From his description of it, however, I judge it occurs in the Cretaceous rocks that prevail about the heads of Slate River, Washington Gulch, and East River. In appearance these specimens approach anthracite more closely than any other coal I have seenin the West ; how closely, an analysis will have to prove. It has a luster like anthracite, and is very hard. I think, however, that it is only an altered Cretaceous coal. I judge it to be of excellent quality. } 269 GEOLOGICAL SURVEY OF THE TERRITORIES. ite, d, similar to that of White Rock Mountain. Its direction as it crosses the creek is northwest and southeast. It is the south extension of an island-like area of granite like that of White Rock and Italia. Snow-Mass Mountain and Capitol Peak are two of the principal high points in this area. On the northeastern side of ‘this belt (at ein the illustration) the Silurian beds are seen resting on the granite, and above are the Carboniferous and Triassic formations. Here there is a turn in the course of the creek. Above the granite belt it follows the strike of the sedimentary rocks. It is this part of its course that is parallel to the main stream, from which it is separated by two ridges, cand f, Pig. 2, Plate XVIII. The first one, /, is composed mainly of red sandstones and conglomerates, probably of Permo-carboniferous age, or possibly in part Triassic. Section 27 was made on the western side of the second ridge, (cin the illustration.) The creek rises in an amphitheater between Station E, or Maroon Mountain, and another high point of similar for- mation. On the eastern side of the valley is a high bluff-like wall com- posed of red sandstones and conglomerates, the latter prevailing toward the base of the cliff. The general dip is toward the northeast, at an angle of about 20°. There is also a slight curve on the face of the wall along the strike of the beds. As we go toward Maroon Mountain the bright red sandstones become darker. Maroon Mountain derives itsname from the color of its rocks. We did not ascend it, but made a station on a high point a short distance south of it. Here the rocks are mostly _ sandstones and conglomerates, a thin bed of gray limestone now and then appearing toward the base of the station. Thesandstones are intersected by numerous dikes, which are probably connected with the main mass of granite. This may account for the changes in color and structure that we notice in the sandstones. All the dikes are irregular. A prominent one intersects Maroon Mountain, and another the ridgethat rises toward it. Hast of Maroon Mountain is a dike, which is probably the southern extension of the large dike seen east of Snow-Mass Mountain, and to which I shall refer again. It is only near the base of Station 76 that we find any limestone. Onthe summit the beds are brownish, becoming red as wego down. These beds are also, for the most part, finer grained. In some places there are circular spots resembling sections of concretions. They are generally white or light yellow, and sometimes have a black central point. Near the base of the hill are’also greenish shales. The beds exposed along the creek at the bottom of the caion are probably of Carboniferous age, while those on the summit of the ridge should perhaps be referred to the Triassic. On the southwest face of White House, or Snow-Mass Mountain, a small branch of Rock Creek rises. Tt soon expands into a beautiful lake, to which the name of Elk Lake ~-has been given. A short distance below the lake, the creek falls over the edges of the stratified rocks to the level of the main creek, a vertical distance of 1,102 feet. It fails over these rocks in two falls or cascades, the white foaming belt of water contrasting with the bright-red con- glomerates and sandstones. Snow Mass Peak is 13,785 feet in height, and is made up of a light-colored granite, such as we saw on White Rock and on Italia. Southwest of the peak, at the, head of the creek flowing into Elk Lake, there seems to be a dike in the granite. First is a band of very fine-grained dark rock, with seams of white feldspar. it is about 100 feet in thickness, and its direction is about due north- west and southeast. Just below it is a band about 3 feet thick, of a green reck, the color of which is probably due to iron. This is prob- ably dioritic. Next to it is about 4 feet of the same rock that we saw first. It is followed by about 50 feet of a porphyritic rock, with a green matrix Se | GEOLOGY—SNOW MASS MOUNTAIN. 26F containing granitic pebbles, some of whichare quitelarge. I have already referred to the fact that Snow Mass Mountain and Capitol Peak are situ- ated in an eruptive center that is distinct from the one in which White Rock and Italiaare included. The latter is more extensive and also more irregular in shape. The amphitheater, on the eastern face of Snow Mass, contains an extensive snow-field, the largest I have ever seen on any peak in the Rocky Mountains. Itis from this snow-field that the mountain was named. To the northeast of Snow Mass, on the east side of Snow Mass Creek, is a high, bluff-like wall, which must be between 1,500 and 2,000 feet high. The most remarkable feature in this wall is an immense bed of eruptive rock, probably granite. At the base of the bluff, just above the bed of the creek, are exposures of beds that from a distance f judged to be Silurian. Fragments of these beds are also seen on the opposite side of the creek resting 6n the granite. The dike is about 600 or 800 feet in thickness, and has just below it what I think are Oar- boniferous beds, although on this point I cannot be certain, as they may be Triassic. Above the dike in some places is a capping of red sand- stone. This has been removed in other places by erosion. As we go southeast along the ridge the dike diminishes in thickness. The dike I referred tc as extending back of Maroon Mountain is probably an ex- tension of this one. In the latter place, however, its dimensions are much smaller. To prove that they are the same the line would have to be followed. There are a great many of these dikes in the sedimentary beds dipping away from the granite. The large one just referred to, and shown in the illustration, is very easily explained. In the upheaval of the granite the sedimentary beds were of course broken through, and wherever there was no resistance the melted material intruded itself. The planes of stratification afforded points of weak resistance, and the beds were forced apart.. Subsequent erosion, effected both by water and by ice, has carried away so much material that the connec- tion with the main mass has been cut across, and we have at present the appearance as seen in the illustration. To fully investigate and work up in detail all of these dikes would require that each one be followed throughout its whole extent. Some of them would probably be proved to be trachytic, but I am of the opinion that if they could be traced to the granite they would be seen to grade imperceptibly into it. I think the entire mass of granite in the Elk Mountain district has been in either a plastic or a melted condition, and that the granite is eruptive. It is a question whether or not it is remelted metamorphic rock. The future will have to decide this point. The elevation of the range was Post-Cretaceous. The erosion since its elevation has been enormous. The different peaks are connected by sharp, semicircular ridges, each the ruin of a huge amphitheater, in the center of which the granite © appears. On some of these ridges the sedimentary beds form a capping. The occurrence of these sharp ridges, high peaks, and these huge amphi- theaters, renders traveling in the heart of the Elk Mountains extremely rough. All the peaks are somewhat difficult of ascent. Looking northeast from Snow Mass Mountain, on the ridge beyond the one in which the dike is seen, cappings of light-colored beds appear along the summit. These are probably a portion of the Cretaceous beds that slope from the Elk Mountains toward the valley of Roaring Fork. They will be referred to again in a subsequent portion of the chapter. Capitol Peak is about three miles from Snow Mass, and has an elevation of 13,816 feet. Judging from its appearance, as seen from Snow Mass, it is similar in structure. West and southwest are the inverted beds Shown at fin Fig. 3, Plate XVIII. Northwest of the peak the relations 262 GEOLOGICAL SURVEY OF THE TERRITORIES. of the beds are as shown in the section from Capitol to Sopris Peak, Fig. 1, Plate XX. Leaving Rock Creek we proceeded down Hast River to Cement Creek, and then crossed to the Gunnison, which we followed to one of its sources, and then crossed to the head of Difficult Creek, one of the branches of Roaring Fork. The divide between this creek and the Gunnison where we crossed it was 11,619 feet above sea-level. The rocks here, which are all granitic and gneissic, were referred to in the preceding chapter. On one of the stations (76) near the head of the creek, I found fair specimens of rose quartz. The view from this station looking westward was ex- tremely fine. In the foreground we had the low ridges, heavily tim- bered with dark-green pines, beyond and above which the mass of mountains about Castle Peak towered, their somber blackness relieved by patches of snow. To the right and nearer us the dark colors changed to a deep orange, streaked by light gray wherever there were slides of rock. Still more to the right we had the red sandstones, their bright color contrasted with the grassy slopes on the rounded hills. Beyond and reaching high above, bathed in sunlight, stood the Capitol and Snow Mass Mountains, their immense snow-fields glistening with silvery brilliancy. To the right of the Capitol is a prominent point seen from all parts of the Roaring Fork Valley. It is noticeable for a bright yellowish band which is distinctly outlined in its face, like the band onanescutcheon. It may be a dike. We did not have time to visit the peak to determine to what the appearance is due. The creek we followed to the main Roaring Fork is densely timbered, and just before reaching the main stream plunges abruptly down a steep hiil about 1,000 feet in height. Here we had to work about six hours in order to get our train down. One thing par- ticularly noticeable when we reached Roaring Fork was the change in the vegetation. On the Gunnison we had seen but little in the way of vegetation besides the sage-brush, (Artemisia.) On Roaring Fork, how- ever, we found a profusion, among which we noticed the scruh-oak, (Quercus alba,) a willow, (Salix,) two species of raspberry, (ubus deli- ciosus and R. strigosus,) the service-berry, (Amelanchier canadensis,) the common currant, (ibes rubrum,) and the common wild rose, (Rosa blanda.) The upper part of Roaring Fork is in cation, emerging from which the stream flows through a valley that gradually increases in width, and is filled with drift that has been carried down by the water. Above Cas- tle Creek this drift is made up principally of granitic boulders. Castle Creek is the first large creek coming into Roaring Fork from the left side. It drains the east side of Castle Mountain, one branch also heading on the west side of the peak. Allthe branches have cut deeply into the red sandstones exposing the carboniferous layers below. A short distance "above the mouth of Castle Creek Hunter’s Creek comes in from the east. It is here that we first meet with the stratified rocks. The Silu- rian quartzites cross the main stream, and the line of outcrop extends up Castle Creek. On the east side the dip seems to be north 35° west, angle 25° to 30°. On the other side the beds are more highly inclined, and dip in about the same direction 50°. From this point the valley widens, and is covered with an extensive deposit of drift, a large portion of which was probably derived from the Elk Mountains. Indeed, this is shown by the great quantities of red sandstone boulders in the bed of the stream. This deposit is cut into terraces by Roaring Fork, and all the branches coming in from the southwest. The terrace on the right side of Castle Creek is 130 feet in height. On the opposite side it is about 210 feet in height. The next creek below Castle Creek, Maroon Creek, is also large, and drains the portion of the Elk Mountains east HOM ia ae in SOWIE MOLT NM LOZ IOS GALE = PAU2ud ~ Gey ULO EL. DUMBO YO ALG 7402200, cA VAN A MOe Gu, \} < y 3 S N LIE © N CH ~ 8 S eS Sy 5 egg tYloe DURIMORL S9OLID UOWI POAT r Lees A N pe em ee . CE aS 2 eae ‘6T ©9ld te (yaad: PEALE.] GEOLOGY—SECTION NO. 28. 263 of Maroon Mountain. The profile across this creek is shown in Fig. 1, Plate XIX. Here on the right side we have three steps, the first, a, being 15 feet; the second, b, 35 feet; and the third, c, 50 feet. The latter is about 4 feet above thelevel of the stream. The tops of the upper terraces seem to have a general level, and are overgrown with sage-brush. Along the streams at the bottom of the small canons there is a growth of aspens and pines. Between the mouth of Maroon Creek and Roaring Fork there is a conical-shaped butte that rises about 350 feet above the general level. This is represented at A in Fig. 1, Plate XIX. The following section was made here from the point d in descend- ing order: Section No. 28. d. 1. Soft fine-grained yellow sandstone. At the south end of the butte there are two small faults in this bed and in the bed next below ; thickness, about 20 feet. . Red sandstones. The upper portion very hard, becoming softer and shaly as we godown. They become greenish also as we de- scend ; thickness, 40 feet 2 inches. . Very hard greenish-gray calcareous sandstone, with calcite dis- tributed through it; thickness, 18 inches.: . Fine red shales, with a band of hard sandstone in the center, 1 foot. . Sandstone, with a band of shales 1 inch in thickness, 12 feet 6 inches. . Very fine deep-red shales breaking into very small pieces, and having interlaminated bands of hard sandstone each about 1 inch in thickness, 8 feet. 7. Coarse pink sandstone, shaly in places and conglomeritic at top, 15 feet. 8. Coarse pink shaly sandstone, 6 feet. 9. Coarse pink conglomeritic sandstone, like No. 7, but not quite so coarse-grained. The pebbles and matrix are both siliceous, 25 feet. 10. Irregular purplish limestone, very coarse, with shales, 8 feet. 11. Shaly sandstones, 10 feet 6 inches. 12, Coarse irregular purplish limestone, resembling a conglomerate. There is about 5 feet of this and then 1 inch of green shale, be- low which we have a bed of the limestone in structure like the upper part, but of brick-red color; total thickness, 8 feet. 13. Limestone conglomerate, with masses of purplish blue limestone, varying from 1 to 4 inches in diameter, 4 feet. 14, Irregular brick-red calcareous sandstone, with cross fracture. In some places there are greenish bands, 40 feet. 15, Coarse brick-red sandstone with cross fracture, 5 feet. 16, Fine-grained red sandstone, 5 feet. 17. Limestone conglomerate, like No. 13, 8 feet. 18. Irregular brick-red sandstones, 21 feet 8 inches. 19. Red sandstones, compact above, becoming irregular and mot- tled toward the center, and compact below again, 84 feet 10 inches. €. 20. Compact fine-grained yellow sandstone, 77 feet 7 inches. 21. Blue limestones, with interlaminated shales. The limestone is in beds about 2 feet each in thickness, while the limestone varies from 2 to 5 feet; 155 feet. 22. Space reaching to base of hill, 155 feet. Below these beds, on a ridge between the mouth of the creek and bo oOo oO ee w& 264 GEOLOGICAL SURVEY OF THE TERRITORIES. Roaring Fork, other beds are exposed. Here Mr. Taggart made the _ following section. ‘The beds would be represented under the drift at the point fin the illustration, (Fig. 1, Plate XIX.) The beds seem to be conformable, all dipping about 40° to 50° north, 45° east: Section No. 29. In ascending order, by Mr. Taggart: Blue limestone, 20 to 30 feet. Gray compact fine-grained sandstone, 10 feet. Compact fine-grained blue limestone, 50 feet. Fine-grained sandstone, 6 to 8 feet. Space covered with debris, 150 feet. Brown sandstone, 2 feet. . Brown shales, 10 feet. . Fine gray compact sandstones, with small quartz pebbles, 150 feet. . Dark shales, very much broken, 200 feet. 10. Space probably filled with shales, 200 feet. 11. Brown limestone and shales, alternating, in beds from 1 to 2 feet in thickness, and containing fossils; total thickness, 30 feet. 12. Blue limestone, with interlaminated shales, 150 feet. This is as far as Mr. Taggart was able to carry the section. Bed No. 12 corresponds with No. 21 of section 28. When we cross to the east side of Roaring Fork, the beds on the hills are very much obscured. Enough is seen, however, to warrant the conclusion that near the base of the hills, g, are yellowish sandstones and shales. Above these are outcrops of red sandstones, h, dipping north 15° east, and inclining 50°. I am not satisfied as to the age of these beds, although I think it is probable that they are either Carboniferous or Permo-carboniferous. The beds given in Mr. Taggart’s section dip conformably beneath those given in section No.28. They are undoubtedly Cretaceous, as proved by the fossils. he obtained. Bed No. 20, in section No. 28,is probably No. 1 Cretaceous. There would seem, therefore, to be an inversion of beds here, although it is difficult to imagine what should cause it. Iwas unable in the short time at my disposal to determine accurately the relations of these beds shown in the butte to those skirting the Elk Mountain range on the northeast. Crossing to the opposite side of the valley, the Cretaceous beds are seen dipping to the northwest. The line of outcrop follows the course of the western branch of Maroon Creek, and then turns to the northwest along the edge of the eruptive area about Snow Mass and the Capitol, and continues across toward Sopris Peak. The dip seems to change also, being at first northwest and gradually changing to the northeast. At the points 4 and Jj, in the illustration, Fig. 1, Plate X1X, we have two benches, with a gradual slope toward the nor thwest. They are covered in part with a growth of aspens, and strewn over the surface are numerous granite boulders of all sizes. These benches, I think, must mark the old courses of Hunter’s Creek, that joins Roaring Fork ‘above the mouth of Castle Creek coming in from the east. They. curve toward the present bed of the stream. About two miles below the butte through which the section given above was made, the river euts through the Cretaceous beds, leaving a high bluff on the west side in which the beds are inclined at an angle of 15° to 20°. Opposite these bluffs is a level valley filled with drift, which reaches to Cretaceous bluffs on the east side. The river cuts its way deeply into this drift, which is underlaid by Cretaceous .rocks, as is shown by several expo- sures along the course of the river higher up stream on the east side, just SO VD Os 09 bo bt J DVVMEPZTD say zp ala . op pear ae Wee ZACZALA LED Za ALL 2207777 SA ye ema sazgig pojicleay on suidlop Wolf UOROOTAL g S: Q S 3 7027, S\) N . EX eld ey GEOLOGY—FRYING-PAN CREEK VALLEY. 265 below the butte. Beyond the Cretaceous beds on the east side of the river, which are, I think, at this place right side up, there are ex- posures of red-beds, which I did not have time to visit. About eleven miles farther down stream, Snow Mass Creek comes into Roaring Fork from the southwest. This creek has two large branches, one of which heads near Maroon Mountain and Snow Mass Mountain, while the other, Capitol Creek, rises north of the Capitol. Opposite the mouth of the ereek there is a hill capped with a volcanic rock, which is also exposed on the southwest side. It seems to be trachytic in character. eogsecacn Do. 2 | ANA SCONC) -jereie aie serene alent Do. 123-125 | Sandstone shale Do. M26) |USANAS5ONC) see. -n eee sn ee cee Do. 127, 128 | Micaceous sandstone shale Do. TA) EG Ohya () )paesece pele ered babocceerer CaebeneCe Head of Iowa Gulch. 130,131 |.-.... do «ESRD DEED Ob edo ne odes acon oDadae Stray Horse Gulch. HS Qa te ciate yain Olean atsyaipmm ie Nearer ol eletbla mfemtotsimraids sis bas Says Near Fair Play. 133 Gracie (Botsdam), 2.42 ct emcee tee ceccssec Horseshoe een ae Pra Oty GS) 8 Soe a) clot asain Soe ekccwcccaces South side of Four-Mile Creek. eon ln GUESS 26 aac eee mia hts aio ee ete dos a asic as Horseshoe Mountain. PSG MG TANS sess. 22 ech Gate cele te Adodt eee cyecee Do. un Guartzite, (EP OtSGAM)). a: sac seleelse serie seine ass Do. Liu) || (GU Cr Pees Bec ermcter G.-2ocabeo Loa DOO r Crt ECE Weston’s Pass. SUM LLC GG) (4) eee sedate Be ah aio winlable selena nica diditee Buffalo Peaks. do Do. Do. Do. Do. Do. Do. Mount Harvard. : East of La Plata Mountain. No. | Name. Locality. 48h @ narbysee esecise elem ciel ee cei sen eminem East of La Plata Mountain. 149 | Quartzite ------ 22-5 coos cece cen meee nese: Do. 3 TE) |) Ty OMS) socone Soon eSousoo Sb obeEBoodsococeadac Do. 151-153 | Trachyte ..-...----..-- Near Grizzly Peak. 154,155 | Obsidian rock......-.-.- Do. 156 | Trachyte breccia Do. 15%) Rny olite) (2) a- seet je a= ae eit = == sodisaqgceqaas Do. USI) ooosca GD) sgdcdemasadaesosoog d= clucddocsHasecesssS Do. UBS) |ossas6 Ol) CBee esa dSab saan saeoe onadegesibobegadees Do. GD) || Ae NI) Secs SasGece seuos cos de poeccOosgoaoDoRc Cation of Lake Creek. NGG} || @Qiene 7 cocaasaqoeenscdosdooTs0=sooncoeococsode Red Rock Pass. 164,165 | Drachyte -.2.-...-----\- 2.22 --e-c--|4-------- Do. GR, WH || GUGnEE Se scsccosas seek a = 5555550505650 500ee0bess Do. 168-170 | Trachyte ...........--.------+---------------- Do. ISG MmanibOneesee sete ee creeeiserecee ce Seeeierera Do. 174 | Chlorite-schist Do. 175 | Mieaceous gneiss .-..--.---------- Rides South of Red Rock Pass. 176,177 ) Trachyte ....--.--...-----.-+----------------- 178) | Mottled quartzites 2. --cmessecm le eaele eisai Head of Spirifer Creek. 179,180 | Porphyritic trachyte ......--...-------------- Eastern Branch of Taylor’s River. TST ATIEBS |) TBM) (osnecoa coscooosososucmecdseaq000059 Do. TESS abe Gli wate eee eA aa sucunmaacorogaGuoc[d Do. TSE TSS) || (Ghent) ococoocaa sno ceaaoeuuocatoustsga seuece Italia Mountain. 189-191 |....-- CU SaubeEceormEoubadoses sbacaoersaoe B6q00 Ridge east of Italia Mountain. 192, 193 | Gray calcareous sandstone....---------------- Ridge south of Italia Mountain. 194 | Red sandstone .....--..-------+----------+----- Do. 195 | Micaceous-sandstone shale Do. 196 | Greenish sandstone.....--..----- Do. HOPERO) |p MEA ING (O)esocce seocodooceseogpessseqasengs0 Dike on Cascade Creek. 201 | Brownish-red sandstone ......-.-------------- Cascade Creek. 202 | Red conglomeritic sandstone..-........--.---- Do. 903 | Maroon-colored sandstone.......-----++-+----- Teocalli Mountain. 204 | Light-purple sandstone .......-..-----.------- Do. 205 | Coarse gray sandstone .--..:-2--.---!--------- Do. 206 | Coarse ereenish Sandstonesenenacseeeecesereee Do. 907 | Brown sandstone ...- ise ccele co enccdsbecesceene Do. By} |) Garhtine (Mesos toseso cnosadocsddonsdauesoousnas Do 209 | Red calcareous sandstone ........---..-------- East side of East River 210 | Pink-caleareous sandstone ......---..-.---..%. Do. 211 | White sandstone, (Cretaceous) Deo. 212, 213 | White limestone, (Cretaceous) oe Do. SEONG |) (Gucimtlivels scases neacad casanacsacos cosensooasoans Snow-Mass Mountain. OXIME) kOe GON Be ee SC adba Ludadooalidasuaqade Do. PAD Nessdae Gla) sob scceonosansesesoosoSsooonaSesasccse Do. 221 | Brown calcareous sandstone .......----------- Maroon Monntain. 222 | Coarse gray sandstone.......-...------------- Do. 22359024 | Red sandstone) = 522-2 -leeee sees atone Do. 295 | Laminated limestone.-........-...--.---------- Do. 226) |) Mrachy tel (2)iesecene) © seine eee nee eect Do. 227 | Calcareous conglomerate .-...-.-------------- Do. 228 Metamorphosed argillaceous slate........----- Near head of Rock Creek. 229 | Green metamorphosed sandstone ...-.--...--- Castle Peak. 230 | Conglomerate sandstone ...--...---..--------- Do. 231 Trachyte (soos omioso sosoasdonacsnoscoousasaed Do. 232 | Conglomeritic sandstone.....-..--.----------- Donne 9350034) )Purplish trachy te) sss esses eek es le ae East River, below Cement Creek. 235 | Light-gray compact limestone pistes le sccc ese: Station 72. 236 | Glauconitic limestone..........-.-.----------- Do. Osfaleblackelimestonemeeceeeeees seetesncentcisetesrerats Do. 238 | Calcareous conglomerate........-----..------- Do. 239 | Cherty limestone 32-2 o-aaace =a Sec eine ae Station 73. 240 | Purplish-gray limestone Do. 241 | White sandstone........---2-.---se--++ : Do. 242 | Red shaly limestone .| Ridge northeast of Station 72. O44o | MIIMEStONG weno eee sales eee eceriolseciciaisaiciels Station 73. 245 | White sandstone.-....-------.+---+----------- Do. DdGniMMaca-SCHISt oc eecne sweet eae tesa ieieinicie Do. Qa) Redvoranitey )-seeseenesemasskeneiseelenaisatee == Do. O48 iGrayatrachybeeeseeriee eee eee emeee ae ce ceclac Below Station 73, on East River. 250 | Light-gray gneiss.....-...---..--..------ -----| Union Park, on Gunnison River. RAL GRE) || IRWsls CRNA A Goede decosoesopeossuduboeodsaneeor Station 76, near head of Roaring Fork, DEB (CHES cooecesee poesia nerooone oa saconoEnoaabamts Station 76. O54 Granibeporphynyeeseeeeeee eee eececnescs cael Head of Roaring Fork. 255 | Gray calcareous sandstone Roaring Fork, near Castle Creek. 256 | Coarse red sandstone ..... Station 78. 257, 258 | Chloritic schist ..........-..--.--..-. Sopris Peak. 2507 HG raniuoreece meee cee ciewia clean Bnei clcietaeeraiare Do. 260 | Coarse red sandstone ........2.....-.2----- .--| Erying-Pan Creek. 261 | Micaceous sandstene...............----.------ Do. 262 | Fine red sandstone.--....-....-. iilesigleatatar eles Do. 263 | Compact red sandstone ..-.....-...----------- Station 82. 264,265 | White gypsum....... .-. dicho em mcineeetalatarals .-..| Frying-Pan Creek. GEOLOGICAL SURVEY OF THE TERRITORIES. Catalogue of rocks collected, §-c.—Continued PEALE] ¢ GEOLOGY—CATALOGUE OF ROCKS. £13 Catalogue ef rocks collected, &c.—Continued. No. Name. Locality. 266-268 | Blue gypsiferous limestone ...-..----+-------- Frying-pan Creek. 269-271 | Gray gypsiferous limestone.-......------.---- Do. Q72 | Gray limestone .--.yeenee- open rn nnnnnewe eee e- Do. : 273-275 | Calcareous tufa.....-.----+~------------- Sao North Fork of Frying-Pan Creek. 76 | Brown micaceous sandstone, (Permian)....--- meee yer opposite Roches Moutonnés - , reek. 277-279 | Green conglomeritic sandstone .-..--.-------. Do. 280 | Brown shaly sandstone ...---n-+--e------->- => Do. 281, 282. | Limestone .-...----..----- ----p2e- eee eee eee Do. Mee 283 | Pink conglomeritic sandstone ----.--.--------- Do. ek 284,285 | Coarse green sandstone ..--.-.----------------- ‘Do. 286 | Green sandstone conglomerate..,,------------ Do. 2 287 | Dark-gray micaceous sandstone...-....----.-. Do. us? 288 | Coarse gray sandstone, (Carboniferous) .---.-. Do. ped 289 | Coarse white sandstone. .....,. sonpensemosdsse Do. oe 290 | Pink conglomeritic sandstone .....-. wpoosens = Do. 291 | Fine red sandstone, (Carboniferous) ----.----- Do. ZED || Merona (()) aacesnocodossacsescccg Adomedioconss Do. Bee - 293 | Black flinty limestone, (Silurian) -.....-.-..-. Do. PETA Grsstie = 294 | Quartzitic conglomerate,-,.-» »--r- Do. a 295 | Coarse red sandstone....,,-.,- Do. 296 | Greenish-gray sandston@-,----------e--------- Do. 297 | White QUATTZILC «10+ y 2 epee ee iee o ree popasoes Do. 298-301 | Gneiss........... anopecesces sSScmonsaced coeses Mouth of cation of Eagle River. 302) TPrachyte (?)-.-- v-oyer-ec-r-=--ep-eree---+---- || Hast side of Hacle River. 303 | Trachyte -.....- 5006 Srapeneresononmeceoacdias Forks of Trout Creek. ‘' 304 | Greenish sandst0ng....y---s---rereeercee----- Small park at head of Tront Creek. 305 | Gray sandstone...--...--2-;e-serperrganee---- Do. 306 | Blue argillaceous slate..,----------pr+-------- Do. 307 | Light-red sandstone ....-----r-p-pepenprer---- Do. LIB OR SENG oc ooongscHosarcmendesenanompoascone Do. WMPY Cas) a aarostaakesnee Boer erenee ene Poh aad Butte east of salt-works, South Park. Impure gypsum. ......--.-5---~ mogonuaonasesas Butie north of salt-works, South Park. Gray LIMeEStone lees sce pese aa wess pacsieeeeeks Do. Sent ; Sandstonoshale-peceecesscercsse coe ccemene Do. Bio OLO || (Dlaek Py PSUs. coe ciwapeccimrisiaeisancieals x Do. 317 itO------- Butte east of galt-works, South Park. 318, 319 | Trachyte ....-.- eer eos PeRSe WaT MESLOUD ors oe ow nie Jaengptioancer sees ps acersn| Edge of salt, marsh, east of salt-works, South Park. $28 |! WWerGints) oncosde cannon oonodcsanenotoacsSaseaee Butte at bend of Little Platte River. esd 200 | OATGRLOUE sich ys sin cicieiac’s om civ we nir vinpinGenice are East of butte at bend of Little Platte River. 326-329 |.....- GV EE atone oe eae pittiemie se reee Zyueaante ds Station 92, South Park. * So0, dol | Basalt -----.- cpp epee re cone prerese-r--e- | SOuth end of South Park. 332 | Gray sandstone ....-speeyecrvecpercerny-e>----| North of salt-works. 333 | Brown sandstone, ,-, cpp reece eeperrpp en -es--- ™ Do. 534) | PEIN BANGSHONO)-senpaips)enceps specs pings ssc ee Do. 335 | Gray SANdBtONC. .-perer-repeneroppezreper--ee- 0. 336 | Black limestone ..... Snoopichoponamsconmessscos Little Platte River, South Park. 337 | Gray shaly sandston@,--e--p--erpppeee=--20ne- Do, 338 | White sandstone.-.-...,-,c0pp----> SR a etic Do. 339 | Coarse red sandstong .,,,----p--p-prer---- Do. 340 | Fine red sandstone ..... sugaeepesios Do. 341 | Coarse white sandstone Do. 342 | Gray sandstone. ..,..-, Do. 343 | Brown sandstone. . Do. 344,345 | Trachyte ........... mescodcen ee South Park, northeast of Fair Play. 346 | Gray sandptone .-........2/....-2.. Sel Meine Bye hes eid MErachy bel ses se wet iccoes soe se cuccct cmoesncceaes Do.’ 348 | Sandstone shale........... SOpeooansmoCSsenboses Do. BAMA GTAVISRNGSLONES: cenrcsstescnmcee noakeews ceo Do. BODE eR LACIV LC) sceptics aries aaseemene ngoacene sooo Do. 18Gs levdd de Olay ah OF He MeoN: Dil Cie 1 Nee Dé WASHINGTON, D. C., June 1, 1874. Sir: Ihave the honor herewith to submit my report for 1873. As directed, the mines of Gilpin, Clear Creek, and Boulder Counties were first visited by me, with the view to study their geological and minera- logical relations, as well those referring to the ore-veins as a whole as those they bear to the surrounding rocks. In almost every instance where time and the condition of the mine permitted it, a personal examination of the conditions under ground was made, and the report confines itself chiefly to those lodes and mines that have been thus vis- ited. On July 3, I took the field as the geologist of the San Luis di- vision, returning from it to Denver on October 5. Nearly 7,600 square miles were surveyed topographically and geologically during that time, and the results of the examinations relating to the geognostic and geo- logical features of the country are laid before you in the subjoined report. It is evident that on a survey of this kind, where a large area must be traversed in a comparatively short time, geological research cannot be carried on in as much detail as might appear desirable to the investigator. By working in perfect unison, however, with the topog- rapher, the geologist will be able to form a correct idea of the hori- zontal and vertical distribution of formations in a very short time. Four chapters and an appendix comprise the annexed report. The first chapter treats of the mining-regions; and I beg leave to submit it merely as a preliminary report, in the hope that at some future day I | may be enabled to make more thorough and extensive examinations. The three following chapters are devoted to the geology and geognosy of the district assigned to the San Luis division. In the appendix, ‘ Min- eralogical notes” and a “ Catalogue of the minerals of Colorado” are con- tained. At this place, I wish to express my sincere thanks to Mr. A. D. Wil- son and Mr. G. B. Chittenden, the topographers of the party, for their hearty good-will and co-operation during the field-season, and to the latter for the kindness with which he supplied me during the winter with the illustrations necessary for the report. To Prof. F. L. Schirmer, of Denver, and Mr. A. von Schultz, Mr. J. Alden Smith, and Mr. Smart, of Central, Col., [ am greatly indebted for | courtesies shown me. Hoping that the report may meet your requirements, I have the honor to remain, your obedient servant, FREDERIC M. ENDLICH. Dr. F. V. HAYDEN, Geologist-in- Oharg Ge, United States Geological and Geographical Survey of the Territories. 276 GEOLOGICAL SURVEY OF THE. TERRITORIES. CAP Dike ake PRELIMINARY REPORT UPON THE MINING-DISTRICTS OF COLORADO. According to instructions received, I visited the mining regions of Gilpin County, Colorado, about the middle of May, 1873, and subse- quently those of Clear Creek and Boulder Counties. The objectin view was a thorough recognition and definition of the geological and miner- alogical relations shown by the lodes of these localities to each other as well as to the surrounding rock. Owing to the early season, a num- ber of mines that afterward were worked, were not then in operation; and as a personal visit to all, or even only the greater portion of the mines, was entirely out of the question, such were selected for examina- tion as were acknowledged to be the most important ones of the district, besides those possessing any particular interest from a geological or mineralogical point of view, the acquaintance with which seemed neces- sary for a successful completion of the work mndertaken. It is mainly of the mines visited personally that I shall speak in the subjoined pages. The lack of statistics, which may be considered very essential in a mining-report, is to be accounted for by the fact: that this report pre- tends only to examine the geological and mineralogical relations of the ore-bearing veins of those districts. As a large percentage of the min- ing population follow this occupation upon claims in their own posses- sion, for the purpose of‘-making a livelihood, the facilities for obtaining statistics are by no means satisfactory, and it would require more time than I could spend to compile thorough statements of production, re-— turns, &e. A carefully-compiled statement of the work done at the Monte Cristo mine has been very kindly allowed me for publication by Mr. Mills, of Central. From it can be seen an account of the actual cost of working a mine on a small seale, and calculations for more ex- tensive operations may be made accordingly. Neither historical notes nor descriptions of machinery employed have been given in the report, as both have been treated of in Mr. Hague’s. excellent report upon the mining regions of that section. Merely the seognostic, geological, and mineralogical features of the localities under consideration, and their mutual relations, are dwelt upon. Itis hoped that by presenting this character of the mining regions, which has not been sutiiciently done before, more light may be thrown upon their merits. or demerits as such, and more definite knowledge gained regarding their constitution. In order to facilitate the ready comprehension of terms used almost exclusively by miners, and in order to give a more definite idea of the’ questions involved in the subjoined report, a short introduction is given, treating briefly on the subject of ore-deposits. The substances mostly occurring in deposits that are sought after by man are gold, silver, platinum, copper, lead, tin, zinc, iron, coal, salt, bitumen, petroleum, and others, existing partly in their native state, partly in combination with other substances. Two great divisions are dis- tinguished, and imbedded deposits—superstratoid deposits; the former being partially or entirely surrounded by a valueless material, the “eountry;” the latter deposited upon the surface, and containing its: valuable minerals partly as float, partly as a superficial deposit. Im- aa Oth SAN SNS ~ ANS EERE A ONS ere iy =, 1 . DPE LIE COREE TONE PER NES Ae . ~ a on wrens y 4 oh me Har ‘ ‘ ) . Ti . nl Ted Ae ac al Nh 1 yh ET tT a Nt: elias > enews — Ls 5 YARRA EC, PLATE A * eel GEOLOGY-—TERMINOLOGY OF MINING. 277 bedded deposits are more frequently met with, and if is of them the report on Colorado mines will treat almost exclusively, An ore-vein is a tabuloid body of mineral matter, aggregated so as to be entirely distinct from the surrounding rock--from the “country "—in its lithological and chemical character as well as in its physical structure, It is necessary that a fissure—or filled—a vein should he bordered on either side, the sides being called “walls.” As the greater number of veins show an incline to one side or the other, it has become customary to term the wall upon which it rests the “foot-wall;” the one resting upon it, the “ hang-ing-wall.” Frequently these walls are of a different lithological and geological character, as at the Winnebago mine, where the foot-wall is gneiss; the hanging-wall granite. In that case the vein is termed a “contact-vein.” The line indicated by an outcropping vein, if cut off horizontally, is called the “ course,” or “ strike,” of a vein; variation from the horizontal is the *‘ dip;” the thickness is measured from wall to wall. In distinction between a vein and a stratum, the former must be re- garded as representing the filling material of a fissure in the adjoining rocks, whereas the latter—a coal-bed, for instance—is merely one of a succession of strata. From the nature of its occurrence, it becomes evi- dent.that the contents of fissures must be younger than the surrounding “ country;” whereas, in the case of a stratum, it must be said that it is younger than the underlying but older than the superincumbent strata, provided the beds have not been overturned. An exception to this rule takes place when an ore-deposit is formed by pseudomorphie action. Massive deposits may be regarded as local widening of veins, but more correctly as segregations. Impregnations sometimes form deposits of large bodies of ore, as, for instance, the tin-mines of Saxony and Bohemia, but rarely produce a suf- ficient amount of metal to prove valuable, Superstratoid deposits owe their origin mainly to mechanical action, but in part to chemical. To the former class belong deposits of gold, silver, platinum, tin, &c.; to the latter, bog-iron ore, bog-manganese, &c. Veins.are subject: to frequent and often serious disturbances, mostly demonstrated by having caused or causing dislocations, in which case they are of mechanical nature, while other disturbances occur, attributed to chemical action. Dislocations often cause intersections of two veins, (Pl. A, Fig. 1,) of which: the disturbed one.is ‘the older; the younger, disturbing, keeping itscourse. The disturbing vein can either be larger (Pl. A, Fig. 3) or smaller (Pl. A, Fig. 2) than the other one. An occur- rence that can very readily be mistaken for crossing is termed ‘‘ dragging,” (Pl. A, Fig. 5;) and it is important in some cases to determine whether an actual crossing takes place, or merely a drag isfound. ‘Two veins may approach each other at a small angle, touch, and remain in contact for some distance, and then each‘ one turn off again to its own sjde; or they may cross and drag on either or both sides of the crossed vein, (Pl. A, Fig. 6.) If the one vein is rich and the other one poor—at the same time, however, of equal thickness and similar mineralogical char- acter—it becomes necessary to determine this point. It may also occur that .several veins cross several others, (Pl. A, Fig. 4,) in which case, however, all the above-stated conditions remain unchanged. Veins frequently ramify, sometimes the several parts returning to the main vein again, sometimes pinching out entirely. The included por- tions of “‘country” are termed “horses,” (Pl. B, Fig.1.) Usually the termi- nation of veins is effected in three ways: by ramification, (Pl. B, Fig. 2,) where it splits up into a number of smaller veins that gradually thin 278 GEOLOGICAL SURVEY QF THE TERRITORIES. out and disappear, (Pl. B, Fig. 3;) by pinching out of the main vein, (Pl. B, Fig. 4;) and by being cut off, (Pl. B, Fig. 5,) which can occur as the result of considerable disturbance, whereby an entirely different kind of rock can cut off and obliterate the vein. Cuts-off occurring without the intervention of any new rock belong to the series of common dislocations, and in that case the continuation can mostly be found again. This latter takes place very frequently in coal-mines, (Pl. B, Fig. 6,) where the beds have originally had an approximately horizontal position, out of which they are thrown by any disturbance caused either by vertical or lateral pressure. In ore-veins, this kind of dislocatian is not so often met with. Sliding of veins is not infrequently found, as, for instance, in the Greg- ory extension, where the one wall has changed its position parallel to the medial plane of the vein-body. If any irregularities have occurred in the vein, a slide of this kind will tend to increase them, and the vein will consist of a series of accumulations of mineral and gangue matter along its former strike and dip. FORMATION OF VEINS AND LODES. The formation and contemporaneous or subsequent filling of fissures has given rise.to a great deal of speculation. Although it may be sup- posed that an?irregular contraction of the earth’s crust would produce at points fissures similar to those $bserved, their form, in detail, and the character of their arrangement with reference to each ether, would probably not be the same as is really found in nature. An explana- tion of the origin of fissures based upon the recognition of volcanic or plutonic activity seems most satisfactory, and will apply in the by far greater number of cases. Earthquakes of the present day, due to vol- canic activity, form fissures and series of fissures analogous and even Similar to those that are now filled with ores. Without penetrating the earth’s crust to any considerable percentage of its'thickness, a vein will still be practically inexhaustible in: depth until machinery may be so perfected as to overcome the increasing temperature as the descent is made. With the help of the annexed cut, the formation of fissures by plutonic activity will become apparent. If a considerable thickness—a mile or more—is allowed for the crystalline rocks a, any disturbance on the part of 6 would have a tendency to crack the strata or the masses of a, thus giving rise to the formation of fissures; and if b becomes eruptive, contact-veins would the formed between the two formations. The expression of this phenomenon, however, will, as a rule, be local. Circumstances can occur under which it may cover a very large area, but the existence of fissures within a small compass has been observed far more frequently. Another kind of fissures is found that owe their existence to disturb- ances as well, but disturbances having a different effect. If any stratified or stratoid rock is disturbed in such a manner as to separate the strata from each other at one or more points, while they remain in connection at others, fissures are formed between these strata, and their strike and dip will be conformable to those of the strata. After the fissures have been formed, they will be filled. Itis a well- known fact that any excavation in the ground or in rock, such as a cel- lar, tunnel, shaft, &c., serves to collect and partially retain the waters percolating through the surrounding medium. This is infiltration. Taking the term infiltration in its widest sense, it may be accepted as an explanation for the filling of fissures. It remains to be decided, how- PLATE. B. siete 0, eR Bite oo sm . sr ela at = “aly ‘ > 1 ital nate ta wy bee ee . ae \ 1 | 4 i! 4 ~ ey Day eS Se Se dieu papatae peta’ d er ern igt BCT: an ALES > VEE z i; pipes imps“ Red cia 8 ow ae an act a8 zat matiecegy. rs x 5 haere easy ern rou tewerar, SOF) DR hs i Ook ae Ca ‘ ily PEM shy kLis, | . - » iE At aA i ‘f ha vad TS wea te, ee Hy oh Wisp Setters Gist fea nines ht alte thas : £3) WHEE pL to ease Le, A Pe er orl Cae Ce ee a AD ie: Ty! a. Fils zy . boihn ae Raf far odie, 1649 sinbocttellis Sacer tay an Dis bewvte ye tA £43 oo Par stiey COLMA GHEE Bar ee ebay oC joy Kos Beet . La saab arate td Hailes thats vireac: 7a. : a end Pealetinrs ay Maat ion aie Mia rereul viee osiginy ei a: LPO ee dad mse fed oF ini Sr . Pe hal 734 bit) s Lim x PEST bss , Pbaue-sroapts Bh " e hl i ea Ts, Lo re Ls Via ; aes 7 ’ : ' ae ; Mj a uy} et AA PER eE gle. Kaa Fa here Petr = eee) OE ee ee Pe wet E: ELS Cpe aries pi Al’®: "Dh eR Dy a pi waar a 4 jt 2 RS pe er Re dns pes, PAIS Bae, DOMPY shen 9 eae 1, i Hi, ys teat: PoMa0rL IRL ee, > , 3 RO ce ee de j BA) ff Ate OF al RL oe te RR a. Brees Bi hI h T3¢4 at O} baie oT i iy te ms tae gy (ens me wa? 0 “se y be f Th Pag ) ‘ * a OMA ree eT ee) oe Combed structure. Contact vein. expucn.) GEOLOGY—-FORMATION QF VEINS AND LODES. 279 ever, what kind of infiltration is usually employed in filling these fis- sures. Numerous hypotheses have been offered in explanation, favoring infiltration from above, below, from the side, &c.; but the reliable data obtained are too few as yet to admit of any well-grounded view. One fact has been elicited, however, the cause of which is obvious, and may event- ually lead in the right direction towards solving the problem. In a large number of instances it has been noticed that the filled fissure, the lode, showed a symmetrical arrangement of its component minerals, so that by dividing it into two halves, parallel to the walls, these halves would each contain the same minerals in the same consecutive order. This structure has been termed “combed,” and leaves no doubt that the same minerals, at their corresponding positions, were deposited contempora- neously, and that the filling must have progressed from the walls inward, i. €., to the center of the fissure. The why and wherefore cannot yet be answered satisfactorily. Attempts have been made to explain the filling of fissures by the action of electric currents; but it seems more probable that those cur- rents, which really do exist in lodes, are not. the cause, but the result of their formation. SEARCH FOR LODES. In searching for lodes, it is undoubtedly best to simply follow the teaching of sound judgment, combined with empirical and other knowl- edge. Should the gangue-rock be harder than the surrounding “ country,” offer more resistance to atmospheric influences, the aspect of a hill or ridge will often reveal the desired point at a glance. Apart from this very convenient method of prospecting, inquiry should always be made whether at any time mining operations had been carried on in the dis- trict being prospected; if so, the strike of the lodes then discovered— if ascertainable—will always afford a valuable hint to the prospecter. If it is an entirely new country to mining-industry, the experience gained upon former occasions must be applied to decide whether it may look “promising” or not. Valuable and time-saving is the custom of examining the sand of rivers and creeks, because any mineral found in this sand must necessarily occur exposed at some point above the one where it was first observed. Not having obtained any satisfactory results from this process, an examination of the rocks in position, as far as they are exposed, can be undertaken. The color of the soil must be observed, if possible, as sulphurets and iron ores mostly produce a red; copper compounds, a greenish color. Vegetation is an important indi- cator for the prospecter. If it is particularly luxuriant along certain limited areas, or the reverse, it may lead to valuable discoveries. In prospecting for salt and similar compounds, the character of the vegeta- tion is of the greatest aid. After having found any mineral that may have the appearance of an ore, it becomes necessary to recognize its nature, and, if it is decomposed, the nature of that from which it resulted. An old plan in prospecting @ country where veins are supposed to exist is to start from any point where a piece of ore has been found in two directions at right angles with each other, whereby every lode within the one-half of the circle will be crossed. In a country where mining has been, or is still, carried on, it will be of use to make the examination while traveling at a right angle to the usual strike of the lodes. When the presence of the lode has been established, it must be fol- lowed up, and here frequently the skill of the prospecter is subjected to 280 GEOLOGICAL SURVEY OF THE TERRITORIES. severe tests. If the gangue-rock is sufficiently hard to preserve its out-- crop, or if the ores stain the soil, it becomes a comparatively easy task; but when all traces of this kind are obliterated, he must resort to uncovering the lode, unless, again by means of the appearance ol the vegetation, he can follow it up. It has been mettioned above that excavations, &c., serve to collect the percolating waters; and although the fissure may be filled, it will, as a rule, retain this quality to some extent, so that, in a dry country, trees growing immediately upon the lode will frequently show a more luxurious development than their neighbors. For nearly horizontal veins and beds, boring is of importance, but sometimes impracticable. Prospecting in our western countries is combined with so many hard- ships and dangers that great credit is due to those men who spend years of their lives in seeking for and developing the mineral wealth of their adopted home. PART I. In Gilpin County, the mining locality is found within a radius of about three to four miles, starting from Central City, and is distinctly limitable at a glance by the perfect bareness of those hills in which the precious metals are contained. Approaching Central from the east, through Clear Creek Cafion, a number of rounded hills are seen to the left—higher ones to the right. Not a particle of timber remains on those that have been prospected over; no low vegetation has had time to develop. Black Hawk, at an elevation of 7,543 feet, Mountain and Central, of 8,300 feet, are seemingly one continuous town, although provided with three city governments, located in Hureka Gulch, with mines on every side, even in the very centers of the towns. Westward of Central, seve- ral hills are located, also containing a number of«lodes, some of which are being worked. On all sides, this comparatively small; mining dis- trict is surrounded by higher mountains, densely wooded, in which every now and then an isolated lode is found. The geognostic features in the immediate neighborhood of the mines are somewhat difficult to determine with accuracy, owing to the great displacement of rocks that has been occasioned by the search for lodes. Throughout the ‘vicinity of this mining locality, the main rock is a gneissic ene, showing numerous changes and varieties, of which Mr. Marvine speaks-more fally in his report upon the geology of that section. Inthe immediate vicinity of the mines, however, the rock is granitic, sometimes changing into that vari- iety which has been termed aplyte, composed only of orthoclase and quartz. Mostly, it is coarse-grained, inclined to separate in stratoid por- tions, and yields readily to the decemposing action. of atmospheric influences. The accompanying geological map* (Plate 1) will explain the dis- tribution of the granite. Beginning at the summit of Quartz Hill, it extends eastward, keeping a little to the north, with the connection broken only at one point, until Running Hill is reached. Composing the main or entire portion of the small intervening hills, its limit south- ward is defined by their own, on the north mainly by the gulch. This granitic area is superficially entirely isolated from any other, having a main longitudinal direction of almost due east and west, a little north . of west. On Procer Hill, graniteis again found, having the same strike, *The drainage has been taken from the map published in Mr. Hague’s mining report, and also the roads, besides some of the lodes, the location of which corresponded with mine. PLATE. I. | ml Poryhyry Hloiriblentie PLATE. I. ll Uae = R \ a 1 > 1 a LI Auk Geological Map of the CENTRAL CITY MINING REGION mae 7 Porphyry Horriblenie WAH (10 43.119 | ee oe. ¥ a PLATE.I. WAL Sanuurngy \. is newtuomng ‘270-4 {ti 2 TRIO” |: City Colorado x x & é & Section MD 994) L At | HI: sw maoog ALLL amc a Section near Central Ci tty, Colorado BOT [deen near Central City, Colorado Section rat we MM t we Ue He a < pte thaloreee ag elletleahelam : ea tie , tia aif mem At shag at mci ili ial re gay ad nem A Caer Doren whet Spek cam te is SL Une Ns ’ a Sanne GEOLOGY—DISTERIBUTION OF GRANITE. 281 ate. pointing toward some small outcrops of it on Casto and Bates Hills. North of the Winnebago mine, it crops-out; also west of it, and east of the Bateslode. How far it extends westward from the summit of Quartz Hill, 1 am unable to say; probably not far, however. Thisis the extent of the granite, and it will be found that within its limits, or in portions immediately contiguous, the greater number of the lodes are located. Porphyry crowns the top of Quartz Hill, Mammoth, Gregory, and Bob- tail Hills, occurring besides in a dike on the western slope of Running Hill, on Procer, and in a large dike north of Procer. Drawing a line from the summit of Quartz Hill te that of Bobtail, it will be found to run parallel with the main strike of the lodes, parallel with the longitu- dinal axis of the granite—in other words, the porphyritic outflow has a strike parallel to that of the granite, and both are parallel to that of the lodes. Hornblende-rock occurs in dikes having an approximate strike of north to south, composed of oligoclase and hornblende, associated with epidote and garnet. Several, from three to twenty feet in thickness, cross Gunnell Hill, one extending across to Kansas Hill, and one crossing Proger. Lithologically, the rock forming these dikes is diorite, although it undergoes a series of modifications. On Plate IL, a number of sections are given that will explain the rela- tive position of the three formations occurring. Section A runs from Quartz Hill to Running Hill, almost east 20° north. Chimneys of por- phyry break through the granite at four points along that section, always forming the summits of small hills. Probably, without any deep-reaching separation, the granite continues in narrow line for more than three miles. Small patches of gneiss are found every now and then, but are merely superficial. As this section runs parallel to the strike of the lodes, none are cut by it, with the exception of a small one on Run- ning Hill, that occurs out of course contact between porphyry and the granite. Section B runs almost north 5° east from Gregory Hill to Bates Hill, cutting the Mammoth, Gregory, Briggs, Bates, and Mack. Mam- moth, and probably Gregory, as soon as it goes deeper, run in granite only, while the remaining three are contact between gneiss and granite. Section C shows the Mammoth on Mammoth Hill, where it has become contact, while it is not farther east. Section D has a course from south to north, running through Bobtail Hill, cutting the lode. Porphyry, sur- rounded by granite, forms the top of the hill, while a portion of gneiss comes in toward the north, and between this and the following granite the Bobtail is contact. Section EH runs from south to north, starting from the eastern slope of Quartz Hill and continuing over across Gun- nell, cutting in its course the Kansas, Whiting, and Gunnell. The Kan- sas is contact between granite and gneiss, while the rest run entirely in gneiss. On Procer Hill, the granite is of a light yellow to white color, coarse- grained, with yellowish orthoclase, white quartz, and black mica, and this character may be taken as a type. Throughout the district the granite contains small crystals of magnetite, the largest of which are found on Gunnell Hill, almost an inch in diameter. On this hill the granite assumes a more gneissic structure, which it shows at no other point to that extent. On Quartz Hill, and from there eastward to Run- ning, its character remains almost the same as well in mineral con- stituents as in structure. Sometimes the line between it and the gneiss is distinctly marked along the sides of gulches—particularly so on Kan- sas Hill—but oftener it is obliterated. Slight variations of composition are shown by the porphyry, which must be classed among the quartzose. 232) GEOLOGICAL SURVEY OF THE TERRITORIES. The well-known crystals of orthoclase, both simple and Carlsbad twins, from Gregory Hill are contained in the porphyry that forms its summit. On Bobtail Hill it has a greenish to maroon color, containing smaller erystals of orthoclase and numerous small erystals of pyrite. At the dike, on Running, it is more compact, of a brown color, containing, in the microerystalline paste, very small particles of hornblende. Differ- ent from these is that on Procer, very compact, with a large percentage of quartz; it has a light-yellow to flesh-colored tint. The gneiss of the entire region is of one type, although numerous varieties occur. Mostly it is finely laminated, of a bluish color when fresh, brown when decomposed. Black mica accumulates at some points, changing its character into that of a mica-schist. Neither in any of the gneiss or the granite is magnetite wanting. With reference to the relation of lodes to these formations, it may be said that they are extremely simple, being contained either in the gneiss or the granite, if not forming contact-veins between these two, and again found between granite and porphyry. Quite a number of them are contact- veins —sometimes only for a portion of their entire length, as, for instance, the Bates. Rarely can the fact of their being contact-veins be deter- mined on the surface, only a few cases having been observed in which it could be done; but, by carefully observing the walls of a lode, the re- spective formations to which either one belongs could mostly be ascer- tained. Upon the strike or dip of the lodes, these various circumstances seem to have had little or no effect; neither have they, within certain limits, changed the character of the ore. Although it might seem possible or even probable, the porphyritie eruptions have produced no. noticeable change in the lodes of their vicinity, unless it might be regarded as an efiect of this kind that those lodes found in immediate proximity to the porphyries generally yield lower returns in buillicn than others farther off. Two main systems of lodes are found here, those belonging to the one striking almost due east and west, the others about northeast to south- west. Of the two, the former are the most numerous; to the latter belong the Fisk, Gregory, Bates, Leavitt, Prize, and a few small lodes. No distinctions from a mineralogical point of view can be made, neither is there any constancy noticeable in the mode of occurrence of these veins. Contrary to my expectations, the mineralogical character of the ores was found to be a very uniform one, showing little variation in, the number and species of minerals composing them. But one interesting fact was observed, that in the more or less central portions of that mining district the lodes showed but very little blende and galenite— mostly pyrite and chalcopyrite. If an elliptic line is drawn, inclosing just within it all the principal mines of this section, it will be found that the J. P. Whitney, the Forks, Running, and Dallas are nearest or on that elliptic line, and these lodes are all worked for lead and silver, con- taining galena and blende as their principal ores. A limited number of workable gold-mines are situated outside of this circle yet, but those upon which the mining enterprise is chiefly based are within. Disturbances—dislocations—are very rarely found in the lodes of this region; scarcely even any material deviations from the dip.* Only afew of the lodes slope over 10°; as a rule they are very nearly or quite ver- tical. Ramifications occur quite frequently, more so toward the west end of the lode than at the east—a feature which was observed in a con- * A deflection from the usual course takes place on the eastern slope of Gunnell Hill, - where a dike of garnet and epidote rock crosses it,in consequence of which three or four small veins near it were formed that have a course about north 10° east. ee | GEOLOGY—-FORMATION OF LODES. 283 siderable number of mines. As an average width for the lode be tween walls, about 4to 6 feet might be given, although some of them widen out to nearly 30 feet. Taking all these observations and facts into account, we may be able to arrive at some conclusions regarding the formation of these lodes. - Von Cotia says,* “It is still most probable, as von Beust in his criti- cism of Werner’s theory has clearly shown, that the majority of lode- fissures have been torn asunder by concussions caused by volcanic or plutonie activity, or, in other words, by volcanic or plutonic earth- quakes.” In applying this sentence to the case now under consider- ation, it becomes necessary to inquire into the geological nature of the formations involved. The crystalline gneiss is probably the oldest rock in that section. of Colorado, while the granite and porphyry are younger. A simple metamorphosis, a remelting of some one or the other portion of this gneiss at a comparatively shallow depth, would undoubtedly produce the effect of a “‘ plutonic earthquake,” whereby not only the fissures could have been formed, but the granite have become eruptive. Subsequent disturbances from the same direction may have produced the parallel fissures in the granite, while the eruption of the porphyry seems to have been accompanied by very slight or no such demonstrations. Besides the great uniformity among the lodes per se, the similarity shown in the character of the ores within certain limits of locality speaks for a common origin of almost all the vein-matter and ore contained within those certain limits. Although the lodes on the outer edge of the district vary in the character of their ores from the others, this may still not justify assiguing to them an age very widely separated either before or after from the latter. As ore, mainly pyrite, chalcopyrite, galenite, and sphalerite are found in this district, and in a few isolated points argentite. Experience has shown that the chalcopyrite and the finely-disseminated pyrite yield the best production of gold, while galenite and sphalerite contain silver; the massive pyrite, however, only small quantities of gold. Fre- quently bands and veins of this pyrite occur more than a foot in thick- ness, but, as a rule, from two to six inches. Toward the surface, the ores decompose through the action of atmo- spheric influences partly, partly through chemical agents. The result of this decomposition is usually termed “ surface- ore,” and contains, in contradistinction to the ores of lower depths, its gold asfree gold. Pyrite loses its sulphur, as also does the chalcopyrite, and more slowly sphale- rite and galenite, and either oxides, carbonates, or sulphates are formed. From the fact that so little native gold is observed, even with diligent search in the deeper portions of lodes that on the surface show or showed it in considerable quantities, it might seem possible that the gold was contained in the original ore as a compound, and became free through the action of decomposing agencies. Thus far, no experiments that may have been made afford any proof that such a compound of gold should exist, although circumstantial evidence points very strongly in that direction. It is a question that would require for its answer, by means of chemical investigation, the most subtile manipulation, unweary- ing attention, and a large, judiciously selected material. In speaking of the various lodes and mines in the following pages, only those shall be spoken of at any length with which I have become personally acquainted by one or more visits. No further attention was paid to the names of individuals or companies owning the mines, as they * Ore Deposits, translated by F. Prime, jr., 1870, p. 65. 284 GEOLOGICAL SURVEY OF THE TERRITORIRS. “may change hands, while they will not often change theirnames. Min- ing enterprise in the region of Central City is comparatively old, and the more celebrated lodes and mines are well known. Beginning with the main veins of the system, striking about northeast to southwest, the central portion of the rest, and afterward the outside ones will be treated of. The Fisk lode, located on the northern slope of Bobtail Hill, was not being worked at any point during my stay, so that no reliable data could be obtained. It has a strike of east 37° north, with an almost vertical dip. Approximately parallel to it, a short distance west, run the Milwaukee and Devil’s Grip, two small veins. The Gregory lode was not worked at the time. Situated on the northern slope of Gregory Hill, with a strike of east 45° north, it is the first one that was discovered in this region. It strikes the Briggs lode down in the gulch, and has been found at a depth of 250 feet, where it is known as the Gregory extension,and worked. At that pointitis a contact-vein, having the east hanging wall of gneiss; the western, ~ granite. By virtue of a dip of 30° to the east, it diverges from the Briggs, which it strikes. It is here that the case of a slide to the east- ward occurred, alluded to above, by which the vein appears of varied thickness. Some disturbance has taken place here, probably occasioned by slides of the ore-wall, whereby fragments of the granite and gneiss both have been thrown into the gangue-material, and are now cemented together by white quartz. The ore-bearing vein is somewhat irregular at the point where it was exposed—ramifying, connecting again, send- ing off a number of spurs and shoots, and keeping a wavy course. Of the walls, the hanging wall was well defined ; the foot wall mare broken, with gneissic fragments resting upon it. he Bates-Hunter lode begins on the northern slope of Mammoth Hili, runs through Mountain City, and is finished on Bates Hill; strike east 435° north; dip almost vertical. Neither of the two mines on that lode were in operation during May, although I am informed that the Bates took up work again. The Bates is partly a contact-vein. Leavitt lode is located a short distance west of the Bates-Hunter, having a strike of about east 40° north, and is the last large vein of that northeast series. This vein is one of the best developed in the district, and yields an abundant supply of ore. Very little variation from the vertical is shown in the dip, and also the course of the vein is quite regular. -Well-defined walls border the vein on either side, consisting of granite on the north wall, gneiss on the south, to a depth of 150 feet, where gneiss comes in on both walls. The distance between walls at a depth of 250 feet is between 4 and 5 feet, varying but little from the surface down, but seeming to increase, however, with depth. Pyrite and chalcopyrite compose the main portion of the ore, a vein of the former two feet thick being found at one place, while the latter is distributed throughout the gangue-rock in small particles and masses; at times intimately associated with the pyrite, again occurring free from any admixture of it. Galenite and sphalerite occur very sparingly, and may not be regarded as ore. The gangue-rock is composed of quartzitic and feldspathic particles, more or less compactly agglomerated or ce- mented. Sometimes large pieces of quartz will occur, thereby render- ing penetration difficult for the drillers. Although the arrangement of minerals between walls shows some regularity, ‘there is no ‘symmetry about it. (Plate IV.) In this mine the following minerals were found: pyrite, occuring massive and in, small pentagonal dodecahedral erys- tals; chalcopyrite, massive; sphalerite, in narrow seams, running through ae GEOLOGY—BOBTAIL LODE. "285 the quartz; galenite, in little cubical crystals, contained in the gangne-rock aS a matrix; quartz, as vein-matter and in small crystals; orthoclase- feldspar, partly decomposed, forming caolinite, found in the gangue, and delicate flakes of a white tale also contained in the gangue. It is stated that during the month of May, 1873, 745 cords of ore were hoisted from this mime at $ ounces per cord. A cord is between 7 and 8 tons. With the Bobtail lode we commence the second series of veins, striking approximately east and west. This lode is located on the north- ern slope of Bobtail Hill, which was named after it, and has a course of east 8° north. A number of claims have been taken up on the same lode, so that it is necessary to mention that the mine on this lode that will be treated of in the following pages is that owned by the Bobtail Gold-Mining Company. At the western end of Black Hawk, a tunnel has been driven into Bobtail Hill in a southerly direction, intending to strike the vein, which was accomplished after driving something over 1,200 feet. At the point of intersection, the shaft had reached a depth of 480 feet, and was then sunk farther. The vein runs between granite on the south side and gneiss on the north, and is, therefore, a contact-vein. Possibly the gneiss on the northern side may not extend down to any very great depth, because its outcrop is isolated, in which case granite would supply its place. A dip of 15°.to 20° to the south was observed at the lowest level, while higher up it seemed to become almost vertical. The distance between walls may be given from 1 foot, where the vein sends out shoots or ramifies, to 5 feet. Very clean and well-defined walls are found separated from immediate contact by the characteristic narrow clay selvage. To the west, the vein continues beyond the shaft of this mine in @ regular course, while it splits toward the east. Whether this split, that had reached a width of about 18 feet in one of the levels during my visit, will continue, or whether merely a “ horse” comes in, could not then be determined, but the latter seemed more probable. With the exception of this case, great regularity in every feature characterizes the Bobtail vein. Small spurs, from the thick- ness of a sheet of paper to several inches, separate from the main vein and enter either wall. The ore is, as in the preceding instance, pyrite and chalcopyrite, massive quantities of the former having been found up to 9 inches in thickness; of the latter, of several inches. A partly symmetrical arrangement can be noticed by observing the diagram taken at a depth of 520 feet across the vein. (Plate III.) Pyrite occurs on either side of the vein, next to the wall, separated: from it by a narrow selvage, then scattering quantities of chalcopyrite and isolated threads of sphalerite and galenite are found, until the middle again is formed by a thicker band of pyrite. Of minerals, the following were found: Pyrite and chalcopyrite, mass- ive, and the former in crystals—rarely, however, in cubes; sphalerites, in erystalline threads; galenite, dispersed either in threads or small erystals ; mispickel, massive, with pyrite, or in small crystals on quartz ; gold, showing crystallized faces, on quartz; composing the gangue-rock, gray and white quartz, a pink, yellow, and white orthoclase, partially decomposed : flakes of tale and clay in the selvage. As the Bobtail mine is one of the deepest in the central mining- region, a trouble that is not yet experienced to any extent in mines of less depth occurs here. It is the accumulation of water, which has been very efficiently overcome by means of a pump supplied with a Movable suction-hose, which has been placed in the second lowest level. 286 ° GEOLOGICAL SURVEY OF THE TERRITORIES. Mining is carried on pretty much upon the same plan of working throughout this section; therefore mention will be made of it only in concluding the first part of this chapter. The Briggs iode is situated between Gregory and Bates Hills, in the gulch parallel to which it strikes, having a course of about east 3° north. It is acontact-vein, having the granite of Gregory Hill as a south wall, the gneiss of Bates for a north wall. Between walls the distance is about 4 feet at the surface, gradually increasing with depth, so that at 545 feet it is 11 feet wide, while a little higher up it bulges out to 27 feet. This considerable lateral extension, however, is owing to a number of gneissic “‘ horses” that occurred there, causing a splitting and widening of the vein. Although not disturbed to any extent, the walls appear rough at some places, which is due to the fact that at some points there seem to have been dislocations at one time, whereby por- tions of the wall were broken, and cemented again by quartz. Asarule, it may be said that the south wall is smooth and of a geod character. Dislocations of the vein are very rare, scarcely even variations in the almost vertical dip being noticeable. Pyrite and chalcopyrite, as usual, form the bulk of the ore, with sphalerite and galenite as accessories. At the depth of 545 feet, a vein of massive pyrite 4 feet in thickness wasfound. Quartz and feldspathic minerals, together with fragments. of granite and gneiss, form the gangue- rock. Minerals found are: Pyrite and chalcopyrite, the former also incrystals; gal lenite, sphalerite, gold, dolomite, quartz-crystals in small cavities ; quartz, feldspar, and mica in the gangue. The owners of this mine are the Messrs. Briggs, one of whom, Mr. G. Briggs, kindly fur- nished me with some data regarding wages and contracts that will be found at the end of part 1. The Mammoth lode, beginning on Gregory Hill and running across westward on Mammoth Hill, has a strike of about east 10° north, show- ing a curve toward the north. A connection between the Bobtail, Mammoth, and Illinois has been supposed to exist, and may exist, but not sufficient proof has yet been produced to substantiate the supposi- tion. The very similar character of the ore and the percentage of gold decreasing westward might speak for such a connection. On Gregory Hill this vein runs in granite, coming up very near to the porphyry; while on Mammoth Hill it becomes a contact-vein. between granite on the south and gneiss on the north wall. Along its entire course, the width of this vein between walls is considerable—between 20 to 30 feet—con- taining large quantities of pyrite, with some chalcopyrite, too poor in gold, however, to pay working at present. Its dip is almost vertical, and the walls seem to be clean and well defined. The Winnebago lode, opposite the Mammoth, on the north side of the gulch, located on Casto Hill, has a strike of about east 4° north. Gneiss on the south side forms the hanging-wall, while granite borders the vein to the north. Clean walls, at some places almost of a polished appear- ance, characterize this contact-vein : dip to the south of about 8°—12°, varying at different depths, strongest at the top. A shaft has been sunk down on the vein, first inclined, then vertical, following it in its course, and the depth reached is 350 feet. Between walls the lode is from 34 to 5 feet thick. Near the western end of the Winnebago claim the vein seems to split; but as it does not split into two equal halves, and the continuation of the vein can be traced westward on the surface, there is reason to believe that this lode connects with Casto, which is a little farther west, running through granite and gneiss, partially being contact between the two. PLATE.II. | ° BS [ q 6 | s) Winnebago 130 ft. Bobtail 560 ft. rnb ee ORE aN RS a aan IE coe st RIAA TD OE < . ht ey piers en 2 ‘3 ig hs Conventionat Signs «used we Secttorns at Lades Gretiss Pyraizy re ENDLICH.] GEOLOGY—GUNNELL LODE. 287 Following the example of the main lodes of this region, the chief ore is pyrite and chalcopyrite, as seen in Plate III, but galenite and spha- lerite begin to make their appearance in more connected quantities. Quartz and feldspar compose the gangue-rock. Wherever granite forms the one wall of a lode, the feldspathic compounds appear in greater quantities in the gangue than in other formations, or even in such where the granite is hard and fine-grained. In that case the gangue is mostly quartz alone, or the ore-veins are found to traverse the granite itself, without any younger formation of gangune-rock appearing. Of minerals, only the four mentioned above are found, besides native gold, Pyrite occurs here in cubical crystals as well as in dodecahedral. The Gunnell lode is situated on Gunnell Hill to the west of Cen- tral, and has a strike of about east S°north. It has been one of the most productive veins of that region, and is supplied with a number of shafts, the levels driven in the different claims mostly connecting under- ground. Of those claims located on this lode, the following were vis- ited: Gunnell, Pippin, Coleman, and Peers. The latter had not reached - a depth of more than 120 feet at that time, and nothing but surface-ore was obtained, while the shafts on other claims had been sunk much deeper. The peers varied from 4 to 5 feet between walls, with a body of ore 6inches to 2 feet thick, mostly decomposed pyrite. On the Pippin claim, the shaft has reached a depth of about 415 feet, and a number of levels have been worked out on either side. Along its entire length, the Gunnell runs in gneiss, modified somewhat in tex- ture and structure, so a8 to be termed a granitic gneiss. It has clean, well-defined walls, with a slight dip to the south, varying in different parts of the mines. A number of small veins, from mere seams up to more than half a foot, run into the main vein, in two instances travers- ing it, but apparently extending only a short distance on either side. Scarcely any difference can be observed in the character of the ore from that of other mines previously described, except the presence of ereater quantities of chalcopyrite. Pyrite has a tendency to accumulate in long sheets in several horizons throughout the vein of the Pippin claim, which measures, on an average, 4 feet in thickness. As usual, the gangue is composed of quartz, having, however, far less feldspar than in those veins that are in contact with granite. Of minerals, the following were found in this mine: Pyrite, chiefly massive, otherwise in cubical crystals, in distinction to the more cen- trally located mines, where they are dodecahedral ; chalcopyrite, sphal- erite, galenite, melaconite, (as a result of the decomposition of chalcopy- rite,) quartz-crystals, and native gold. In the gangue, quartz, feldspar, and some tale were contained. A shaft of about 250 feet in depth has been sunk on the Coleman claim, to which almost all the characteristics given for the Pippin will apply. Between walls, the vein is a little thicker here than in the Pip- pin, averaging from 5 to 6 feet. Ata depth of 240 feet, a cross-section of the vein was taken, which can give an idea of the distribution of the ore, (Plate III.) On either side, nearest to the wall, is a very consider- able segregation of pyrite, intimately associated with chalcopyrite, and interspersed with grains and threads, even small massive quantities of sphalerite and galenite. Next to that, toward the center, quartz sets in—a light-gray to white quartz—containing, disseminated all through it, numerous small particles, mainly of pyrite, but also of the other miner- als occurring. In this mine there is but very little dip noticeable in the vein, which is bordered by clean walls. Its minerals are identical with those of the Pippin. In all its parts, the Gunnell shows a very 288 GEOLOGICAL SURVEY OF THE TERRITORIES. great uniformity, which can be very well noticed, as it is conveniently opened to some depth at a number of points. ‘ The Grand Army mine, located west of Gunnell, with a strike of about east 22° north, may be only a spur or portion of the deflected Gunnell lode, although the connection has not been traced thus far. The Prize lode, located to the southwest of Gunnell, at one time en- joyed a considerable reputation, but was, not working, however, while I was there. Its strike is somewhat out of course, being east 32° north. Crossing Nevada Gulch, and traveling over southward, we reach another. locality that abounds in lodes, some of which are quite large, and have proved remunerative, while others have been—perhaps temporarj]ly— abandoned. This locality is Quartz Hill, so named from the numerous little quartz crystals that have been and are still found there in the de- composed granite. A long, narrow hill, it stretches along, sloping off gently from west to east, more steeply on its two sides. Where the steepest ascent from the north has been completed, where the gneiss stops and granite sets in, there we find the first vein—the Kansas lode. As most others, this lode is divided into a number of claims, owned by various tndividuals and corporations. It is mainly of the claim worked by the Kansas Mining Company that I shall speak. Taking the entire Kansas lode, its course is about east 5° north, until it deflects about 8° southward, near the Waterman shaft. Along its entire course it is a contact-vein, between gneiss on the north and granite on the south side, keeping a tolerably even thickness of the vein, but varying in the angle of the southerly dip from 10° to 30°. The thickness of the vein is between 3 and 4 feet, with a good body of ore, which receives and sends out quite a number of shoots from and into either wall, while some cross the main vein; and in this case the intersections prove, as a rule, to be richer than the other portions. Converging in one direction are the Camp Grave, (which joins the Kan- sas as Waterman shaft,) the Kansas, and the Burroughs, but whether they actually do come together and form one strong vein—what miners would term a ‘‘ mother-lode”—seems doubtful. Near the eastern end of the Kansas, Tascher’s claim is located, with a shaft of 90 feet in depth, just about having gone through the surface-ore and reached the unde- somposed material. The vein is 4 feet to 5 feet wide here, with a south- ward dip of about 12°, still continuing on eastward. West of Kansas claim is the Waterman shaft, which dips at abont 20° to the south, re- taining its character as a contact-vein. Minerals found in the Kansas are identical with those from the ledes previously spoken of, the only difference being that the cubical form is almost exclusively the only one for pyrite. Sphalerite begins to grow a little more abundant than it was in the central portion of the mining- region. The ore of this lode is said to yield good pay, containing an appreciable quantity of gold. South of the Kansas, running almost parallel with it, is the Monte ’ Cristo Lode, having its course entirely in gneissic granite, striking east 7° north, with the dip almost vertical. A number of small veins, of in- ferior thickness, come in to the main one from the southeast. About 90 feet west of the shaft, the vein splits into two of somewhat unequal size, which seem to remain separated, the gap between them widening with increasing depth. Two hundred and ten feet the shaft has been sunk, and at that depth the vein is found to concentrate its ore, which is more loosely distributed through it higher up into a body of pyrite and chalcopyrite 9 to 10 inches thick. The ordinary width between walls AOE CL EO grt septa rie ber, 4 ‘ PLATE .SV. neue oat RN 5 Sa). | WSS — OQ oat pee a GEOLOGY—GARDNER AND ILLINOIS LODES, 289 is 34 to 4 feet. The minerals of this mine do not vary from those of the others, either in relative quantity or mode of oceurrence. South of the Monte Cristo are the Gardner and Illinois, of a little more northerly strike, neither of which was worked during my stay. The distribution of the precious metals seems to vary constantly, and thus far science has not been able to produce a guide whereby mistakes can be avoided in the appreciation of the relative or absolute value of ore from lodes contiguous to those yielding good profits. In no branéh, perhaps, is a want of this kind so keenly felt as in mining, where experi- ence must always be bought at a high price. Upon a large number of lodes in the district at present under consideration, large sums of money have been expended, but the owners or workers were obliged to aban- don them—temporarily, it may be hoped—for some pursuit more re- munerative. ‘The Alps lode, to the southwest of the Illinois, is reported . as having been doing very well some years since. Besides the mines that have been enumerated here, quite a number of small ones are in operation, only presenting features that would essen- tially repeat those given above, or possessing no further interest. On the other hand, a considerable percentage of the more important mines were closed during the short time of my stay, partly on account of the inability of owners to resume work, partly on account of ae spring-waters filling the levels and shafts, so that the facts given of th gold-mines of this section, taken asaw hole, must necessarily be incom- plete. There yet remain to be treated of, five lodes belonging to this region, located on the outer edge of what might be termed. the lode-circle. The Forks lode, situated on Quartz Hill, in the immediate neighbor- hood of the California, Mercer,’and Flack, has a strike of east 10° north. Gneissic granite composes the walls on either side, which are smooth and well defined, the hanging one dipping about 25° to the south. At present the working-shaft is 250 feet distant from the discovery-shaft, located on the line of intersection of the Helos with the Forks, on which it remains down through its entire depth of 517 feet. Keeping on reg- ularly in its course, the Forks shows very little deviation either in direc- tion or in thickness of vein between walls; the thickness is about 5 feet. Both the Forks and Helos are galena veins, and have as such afforded already a large quantity of that mineral, but the main reliance for re- muneration is upon the silver contained therein. To some extent only has the Helos been worked, as the Forks showed a larger body of ore. Of minerals, mainly galenite and sphalerite are found, mixed with small amounts of pyrite on chalcopyrite. Galenite occurs, from the very fine- -grained feathery variety to the coarse-grained breaking in cubical fragments. Argentite is contained between the single crystals of the latter. Of a similar character is the J. P. Whitney, although scarcely developed sufficiently to admit of any opinion. This also is a galena- vein, showing at a depth of 50 feet a body of galena 12 inches in thick- ness, with other portions of the same mineral at either side of the walls. (Plate IV.) Pyrite and chalcopyrite occur as ores, and yield a small amount of gold; but silver is the main object for mining here; strike is east 12° south. Besides galenite, sphalerite, pyrite, and chalcopyrite, we find small quantities of argentite and cerussite. The Dallas lode is located on the eastern slope of the hill immediately north of Black Hawk. It has been worked quite extensively, and the vein can be traced along for nearly 1,000 feet. Contrary to the usual course, it strikes a little south of east; the exact number of degrees could not be determined by the compass on account of strong local attraction. 194@8s 290 GEOLOGICAL SURVEY OF THE TERRITORIES. A southeasterly dip of about 15° to 20° is noticeable. The thickness of the vein between walls varies from 6 to 10 feet along its line of exposure as well as going down deeper. Galena, mostly of the fine- grained variety, forms a large body of ore in the vein, associated with sphalerite and some pyrite, while the gangue-rock is made up of quartz, with a small amount of calcite. At this point, the sulphuret of cadmium, greenockite, was found in a specimen of sphalerite, which had been thrown out on the dump several years since. In no other mine or other dump was this mineral found, although search was made for it. Besides the minerals mentioned above as occurring, there is chaicopyrite and cerussite. The Running lode is the last one of these galena lodes, and is situated on Running Hill, southwest of Black Hawk. Its COUTSEe iS almost due east to west, with a vertical dip. For 700 feet the vein has been traced and partially worked, reaching a depth of about 100 feet. Single streams of galenite are distributed throughout the vein, (Plate IV,) running parallel to its walls, but toward the west they seem to consoli- date intd one mass, forming a galena-vein 14 to 15 inches in thickness. Sphalerite occurs quite abundantly; less so pyrite and chalcopyrite, which are both found in thin seams, or dispersed throughout the gangue-rock. This latter is composed mainly of quartz, with some feld- spar and magnesite. These four lodes are perfectly isolated i in their character as well as in their position from all the others, and, although they show but little deviation from the ordinary strike and dip of the others, their occur- rence seems out of the regular order of things. In explanation, if one were desired, the view might be offered that, provided heat was ever one of the agents in forming those lodes, those metals requiring a lesser temperature for volatilization are now found to be removed farthest from the center of the vein-system. Another lode that has become famous for its production in quantity of a mineral thus far regarded as a rare species is the Wood lode, sit- . uated to the north of the creek in Leavenworth Gulch, also outside of the regular vein-circle. With both walls of granite, it strikes about east 3° north. When I visited it, the shaft was full of water, and it was impossible to get access. Besides producing the unparalleled yield of pitchblende, it is said to pay well in gold; but as I have no reliable data with reference to the mine at all beyond the fact that it contained and probably still contains pitchblende, it may be justifiable to stop here. It remains to be said, with reference to the minerals found in and belonging to the various lodes, that, almost without exception, pro- ducts of decomposition may be collected on the dumps; for instance, pseudomorphs of limonite after pyrite, sulphates of iron, copper, and zine, and others. | eae ay te Ne Se Gow ti a ee ee fe Dan eee 5 res" Me . Sr Se Ss : on . * Orv) Ff a ani To AP ANE SS TOON expucy.) GEOLOGY—-STTTISAICS OF MONTE CRISTO MINE. 293 Jessee usually gives the owner a certain percentage either of brutto or netto. In leasing the Gregory extension, which may be regard ed as a typical lease, the following conditions were agreed to: Briggs furnishes the steam or horse power; the lessees, the brakeman. One-quarter of the cost of crushing is paid by Briggs, unless they crush any mill but his own. In the latter case they pay the entire cost. Briggs supplies drills, shovels, hammers, &c.; they replace hammer-handles, &c. On ores up to 6 ounces per cord, they pay Briggs 25 per cent.; over 6 ounces they pay from - 40 to 50 per cent. Of the smelting-ore of $100 per ton, they pay 25 per cent.; over $100 per ton, they pay 50 per cent. Ona six months’ lease they must sink 30 feet. Briges has the right to retain 30 per cent. of the profits as a guarantee that this shall be done. Briggs far- nishes the timber, and the lessees are required to timber the mine and keep it in good order. A foreman usually receives but low wages, but has a small percentage of the net profits, however. Subjoined is the statement of Mr. Mills, the data of which are taken from the Monte Cristo mine: Monte Cristo Mine, on Quartz Hill, Nevada, mining-district, owned and worked by James Mills, Central City, Colo.—Statement for one year, 1372, having two miners at work, engaged per aay. EXPENSES. RECEIPTS. 254 cords, or 204 tons, of mill-ore, Yield of 253 cords, or 204 tons, and 14747) tons smelting-ore.. $67 67 MUU OLE see nae eneyee ee eee $3, 132 66 "Wages for miners...... Apa aiaead 2,040 00 | Yield of 14755 tons smelting- Hauling 7st Sse ustews gocccee 175 50 OlGtad Soc soso ceascasodesocod 1,158 17 AVE ia se ea ea ce he 704 50 — —_—- 4,290 83 2,969 67 2, 969 67 pigBlallamen a disk rene 1,321 16 Milling-ore: Yield of 254 cords @ $122.88 per cord, (204 tons @ $15.36 per ton).......... $3, 132 66 Smelting-ore : Riieldioil4e 7) tons @ sels per toms: ss seeetele se eesceas as se ss Ae pa ead 1,158 17 TMfeeal ©, SAPS ate ALL eal ek I avd lh lated eA ah a ane 4,290 83 GROSS COST. Running mine-expenses, wages, hauling, and milling: Milling-ore, 254 cords, $110.60 per cord ore; 204 tons milling-ore, $13.824 per ton. Average assay of smelting-ore, (returns from Boston Colorado Smelting Company :} 14750 tons ore: gold, 22 ounces per ton; silver, 52 ounces per ton. PROFIT. Milling-ore: 254 cords, $12.20 per cord ; or, 204 tons, $1.524 per ton. Smelting- ore: 14/7; tons, $70.674 per ton. Profit on total expense of $2, 969.67, $1,321.16, or 444 per cent. Improvements overground as well as underground were made during the time, and the mine kept in good condition. PAR) LI. Differing from the lodes of the Gilpin County mining-district are those located near Georgetown, in Boulder County, the most extensive silver-mining district working at present in Colorado. Traveling t upward along South Clear Creek in a westerly direction, the cation, which has been narrow for some distance, suddenly begins to open out into a wide, fertile valley of triangular shape, bordered on every side by steep mountains rising abruptly from it. In this valley, in its upper, broadest portion, the mining city Georgetown is located, almost 294 GEOLOGICAL SURVEY OF THE TERRITORIES. as if selected for the beauty of the spot more than for the metal riches surrounding it. Unlike Central, the mines are not located within and all around the town; the mountains have not been deprived of their tim- ber, have not had every stone on their slopes overturned in the search for treasures ; nothing reminding too strongly of civilization has marred the natural harmony of this secluded valley. Steep, rocky slopes of the mountains, with deep-cut ravines, set off to advantage the peaceful ap- pearance of the town they surround. Two branches of South Clear Creek unite a little below Georgetown, and itis on thesides of the cafions that they have formed that the greater portion of the principal silver-lodes are found. A number of veins have been claimed, and temporarily worked, east of Georgetown, on the north- ern slope of Bald Mountain and several others, but little progress had been made there. The main rock of that locality is a granitic gneiss, a curious mixture’ of the two, at times shading into each other very gradually, at times showing an abrupt Hine of junction. Slides and local faults have dis- turbed it to a considerable extent ; noteworthy it is, however, that the lodes have been affected thereby but very little. Local contortions have taken place in the schistose gneiss, which appears as such in a great many places, but within it can be found masses of greater or less dimen- sions that would be regarded as granite. Characteristic of that forma- tion may be regarded the almost entire absence of mica in those gran- itoid portions, while the gneiss is very abundantly supplied with it. Besides this granitic gneiss, a typical granite occurs in these mountains, which I have become accustomed to associate with the appearance of the main lodes. It is of a brownish-gray to light-brown color, rising up in steep bluffs parallel to the trend of the mountains on their slopes and sometimes crests. Harder and more compact than the surrounding material, it has better resisted the destroying agents of atmosphericinflu- ences. Frequently the line of demarkation between the granitic gneiss, which I am inclined to regard as older, is sharp and well defined for some distance, while at other points the two gradually change, one into the other, similar to the fusing together of two differently-colored glass rods in high temperature. In several instances, bands of white and yellowish quartzite accompany the junction, or local accumulations of mica alter the rock into a mica-schist near those places, while the - feldspar is then represented but very sparingly, quartz more abun- dantly. Black mica is a prominent constituent of this granite that belongs to the porphyritic varieties; oligoclase, quartz, and orthoclase making up the rest. At the time of my visit, early in June, almost all the mountain-tops were still covered with several feet of snow, so that examinations regarding the horizontal extent of this granite could not be made so carefully and comprehensively as I might have wished it, although more time would have been required than I could spare. One of the most typical points of exposure is to be found on Brown Mountain, at the Terrible lode, where this material rises considerably above the granitic gneiss, presenting a long line of steep, smooth surface toward the cation, Going farther westward, the granite seems to partake more of its normal character, until that of Mount McClellan, about nine miles from Georgetown, cannot be identified with the one just mentioned. So large is the number of varieties presented by the granitoid rocks of this. region that local observations of this kind can give but a very poor conception of the great changes that take place and repeat themselves. within comparatively limited areas. I will, therefore, take the liberty of .S enn GEOLOGY—RELATIONS OF LODES. 295 referring to Mr. Marvine’s report for a more connected and comprehen. sive discussion of these interesting features. Similar to the conditions observed at Central, the lodes here have mainly two strikes, approximately east to west and northeast to south- west, the former being the more numerous of the two. They show great uniformity in dip, which is mostly near the vertical,.and are rarely dis- turbed. But few of the mines have reached any considerable depth, so that not much can be said as yet about their character of persistency, unless inferences might be drawn, judging from their formation, analo- gous to that of other well-known localities. With reference to the relation that these lodes bear to the adjacent rocks, it will scarcely be possible to apply a single rule covering all cases. It may be said, I think, that the majority of them follow in their course approximately the course of the porphyritic granite, are sometimes contact between it and the granitic gneiss, sometimes have their course within it, and in other cases stand in no connection with it. This granite may probably be considered intrusive, although its age will be by far prior to that of the Central City granite, possibly even not much more recent than that of the surrounding rock. If the hy- pothesis of filling the fissures with their mineral-matter by the agent of heat mainly were proved, the view expressed regarding the relative age of these lodes would find some support, inasmuch as the metals mainly found in them all have a lower temperature of volatilization than those occurring chiefly at Central; consequently would have been dis- missed first from the common reservoir. Porphyry-dikes not infre- quently occur, sometimes intersecting veins, but in no instance, so far as could be observed, occasioning any disturbance. Usually the lodes traverse the gneiss at some considerable angle to its dip; only in rare cases do they strike and incline parallel with it. In the latter case they seem to be younger than in the former, judging from their mineralogi- cal and geognostic character. Dikes of hornblende-rock, with epidote, resembling diorite, are quite frequent in the gneiss, and are almost invariably accompanied by a nar- row seam of minerals, mostly galena and blende. Their strike is at right angles to that of the ore-veins, as at Central, running from north to south. Due west of Georgetown, 8,412 feet above the sea, Leavenworth Mountain rises up about 1,200 feet above the valley, and it is on the south side of this mountain that a number of very valuable lodes were found. The Colorado Central, having a course about east 10° north, is located on the south sidé of this mountain, about 700 feet above the creek. It is avery rich silver-mine as far as the character of its ore is concerned, and has paid well ever since it was worked. Between walls the vein is very wide, no wall-rock having been found on the south side as yet, although nearly 30 feet of vein-matter have been cut through. The north wall is granite and well defined; dip slightiy to the north. Ore traverses the entire gangue-rock, mainly in the direction of east to west, branching off, however, at several points into seams of one-fourth inch to an inch in thickness, which, neverthe- less, pay following, owing to its rich character, but these spurs consoli- date at places, and forma solid vein of ore14 feet thick. Near thesurface of the lode, a mass of float-ore occurs, of the same mineralogical charac- ter as that found at lower depths, although its position there seems somewhat out of place if it is from the same vein. Quartz and feld- spar compose the gangue-rock—the latter mostly decomposed—both 296 GEOLOGICAL SURVEY OF THE TERRITORIES. occurring in small particles as well as in larger mee and they were — probably derived from the surrounding rock. As yet no very great progress has been made in the aevelopmien of this mine. A shaft of 85 feet has been sunk, and several short levels started in both at the bottom and before reaching it. The large percent- age of silver contained in the ore renders it advisable to follow almost every spur, which can readily be done in the soft gangue- rock, so that, although but little headway is made in the working of the vein, it yields large profits. At the western extension of the Colorado Central, a nar- row dike of porphyritic obsidian crosses the vein at right angles, with- out, however, occasioning any dislocation. Constituting the ore, the following minerals are found: galenite and ‘Sphalerite, containing an appreciable percentage of silver; antimonial fahlerz, stephanite, argentite, and pyrargyrite ; the latter two intimately associated with the galenite, the fahlerz occurring in masses of more than several pounds in weight. None of these minerals are erys- tallized, however, but occur massiv e. Galenite is found from the very fine- grained variety, passing through every phase, to the coarse-grained, breaking in large cubical fracture. On the same hill, within a short distance eastward of the Colorado Central, is the Saco, in which operations had been taken up again but a short time previous to my visit. It strikes almost due east and west. A tunnel of 320 feet leads to the vein, the main ore of which is sphale- rite with galenite. As at the Colorado Central, the south wall had not been found, allowing a very considerable width for the fissure. The Star mine is close by, striking parallel with the Colorado Cen- tral with an almost vertical dip. At the time, the body of ore was small, mainly on the south side of the lode. The Equator lode was not worked during my stay; it has a strike of approximately northeast to southwest; formerly it was worked, and yielded good pay. On the hill opposite Mount Leavenworth, to the south, quite a num- ber of small lodes have been found and "temporarily worked, rarely yielding sufficient pay, however, to warrant a continuation of opera- tions. They seem to be local infusions of ore between the strata of gneiss. To the northwest of Georgetown, on Mount Sherman, a number of remunerative lodes are located, undergoing active working. One of the largest and richest there is the Pelican lode. As far as could be deter- mined, considerable local attraction interfering, the strike of the Pelican is about north 16° east, with a vertical dip. The vein is from 4 to 10 feet between walls, widening somewhat the deeper it goes. Another lode, the Elkhorn, has a strike of north 35° east, dipping on an average 20° to the north. This Elkhorn approaches the Pelican both on a hori- zontal and vertical projection, and while in the third level it is yet 30 feet distant from it, 80 feet deeper they have joined ; the Pelican keep- ing its true course ‘and dip, while the Elkhorn accommodates itself to it. Between these two lodes, the intervening rock is gneissic, the same forming the entire south wall of the Pelican. Although there isa semblance ofa wall on the north side, its character could “not be deter- mined; but, judging from surface-outcrops, it seems to be partly gra- nitie, partly eneissic. A dike of porphyry is said to cross the vein in one of the lower levels. Blende and galenite mainly constitute the ore, mixed with small quantities of pyrite, chalcopyrite, argentite, fahlerz, and pyrargyrite. Atthe point where our section was taken, (Plate VI,) in the lowest east level, the vein was 6 feet thick, containing almost in the PLATE .VI. oe Th = ‘ Terrible oe oS : x : 5 3 a, dared seensloewilg ri st } he ih i - Aon Nia ie é thy Resid erp ie EN DEICEE] GEOLOGY—PELICAN AND OTHER LODES. 297 center a body of galena-ore of about 18 inches, intermixed with blende, pyrite, and the silver-ores proper. The gangue-rock is composed of quartz and feldspar partly decomposed. Another section of a central portion of the vein was obtained, (Plate Vi,) given in varying succession layers of the minerals composing the ore,and thus showed a combed texture. The single layers were from one-half to one inch in thickness, and uot all of them could be given in the sketch. Minerals found are those mentioned above, none of them presenting any very fine crystals, mostly massive. Their character is such as to insure avery rich yield of silver wherever they occur, if even only in small quantities. A tunnel 325 feet in length leads to the vein, which is worked upward and downward from it, having reached at the time a depth of 82 feet below the tunnel-level. Every indication of persistence is shown by the lode at that inconsiderable depth, and also upward as far as it has been werked. In consequence of the advent of the Elkhorn, this. mine shows more complicated workings than most of that section. Near the Pelican are quite a number of other lodes, some of which were not in operation, while a lack of time forbid a visit to any but the prin- cipal ones. West of it still, on Mount Sherman, is an interesting vein, the Cold Stream lode, striking north 67° west, into a dip to the, north, varying from 10° to 25°. The foot-wall on the south side is gneiss, while the hanging-wall is composed of porphyritic granite. This is one of the few instances where the vein showed itself to be a true contact- vein between these two rocks. Some distance from the tunnel, proba- bly 60 feet, the vein is suddenly cut off by a strip of gneiss running across it at right angles, but appears again on the other side without being deflected the least in its course. Galenite, with sphalerite, com- pose the main ore of this lode; the former occurring in a heavy body, coarse-grained, breaking into large cubes. Owing to the foot-wall, the vein wavers slightly, forming a sort of scalloped line. West of the tun- nel, a dike of ash-gray porphyry, 6 feet in thickness, crosses the vein, but after working through it was found to continue in its regular course. - Of minerals, the following are found: galenite in fine cubo-octahedra, sphalerite, argentite, fahlerz, pyrargyrite, wire-silver, with the excep- tion of the latter all occurring massive; the pyrargyrite and fahlerz inti- mately associated with the galenite; quartz and light-red feldspar, mostly decomposed, make up the gangue-rock. One of the largest and best known lodes of the district is the Terri- ble, located about four miles west of Georgetown, on the south slope of Brown Mountain. It strikes north 82° east; an abnormal course, com- pared with the others. In speaking of the relation of these lodes to the formations surrounding them, it has been stated above that the porphyritic granite formed a steep bluff, running almost parallel with the localtrend of the mountain. Itis within this granitic bluff that the Terrible vein lies. A tunnel of about 340 feet has been driven at right angles to the lode from the south side, and on the north of it the rock has been examined for the distance of 60 feet. The entire tunnel, as well as the 60 feet beyond it, were found to be within the limits of the porphyritic granite. Keeping its course quite regularly, the ore-vein runs along within the heart of this immense granite dike, varying in thickness and local dip, without any well-defined walls to limit its extent. Numerous little slides have evidently occurred, occasioning the formation of slickensides and breaks in the granite, but no distinct 298 GEOLOGICAL SURVEY OF THE TERRITORIES. wall could be observed. Clay selvages at some places border the ore- vein, but the rock on the outside may contain numerous spurs of that same vein. It is altogether one of the most interesting mines. I did - not succeed in discovering any distinctly differing gangue-rock; it appeared throughout to be the porphyritic granite that filled the places between the single veins and spurs. At certain points, circumstances had favored decomposition, and the gangue, therefore, was soft enough to break with the fingers. Quartz and feldspar were its main constitu- ents; but the black mica, characteristic to the surrounding granite, was just as plentiful as in the gangue itself, so that the conclusion presented itself that, although this gangue must be regarded as younger than the surrounding rock inasmuch as it is decomposed, its ingredients were formed contemporaneously with those of the granite. From 3 to 20 inches in the thickness the main vein varies, sending off shoots and spurs to either side; sometimes they return again, sometimes they pinch out. In several instances, a number of smaller veins were observed to run .. parallel to each other, continuing so for a considerable distance. This was the case at the extreme north and of one of the lower levels, and at this point our section of the lode was taken. (Plate VI.) Granite forms the gangue-rock, somewhat decomposed in the central portion, perfectly sound and hard outside, containing within it four distinct parallel veins, the largest one 5 inches thick. Toward the southeast the veins seem to become more irregular. Galenite forms the greater portion of the ore ; associated withit are spha- lerite, pyrite, (rare,) argentite, fahlerz, and pyrargyrite. A larger number of mineral species occur in this mine than in any other I have had occasion to visit in Colorado. Galenite is found in almost every variety; very pretty crystals (combination of cube with octahedron, the latter predominating) of it occurring mM small cavities near the veins; sphalerite, pyrite, and chalcopyrite, massive; pyrar- gyrite, in minute crystals; argentite, stephanite, polybasite, in tabular crystals; stibnite, rare; silver in form of wire, and leaf-silver; flu- orite, in light-green transparent cubes; baryte, orthoclase, oligoclase, caolinite, biotite, and quartz occurring between the single veins. As stated above, a tunnel of 340 feet leads at a right angle to the vein; thence levels are driven on either side, and a shaft sunk. The mine is renowned for its rich ore, which, as I was informed, is some- times regarded by strangers as a favorite souvenir of Georgetown. Be- sides the lodes spoken of, a very large number have been claimed, and are worked to some extent. Several of the larger ones were not in op- eration during my stay at Georgetown ; others were in litigation, so that no data regarding them could be obtained. © The Payrock mine, situated on Republican Hill, northwest of George- town, I will now mention. Striking nearly due east, the vein pitches downward from the north at an angle of about 20° below the horizontal, and suddenly takes a turn of 45°, (Fig. 2,) so that its dip southward is only 25° instead of 70°. Porphyritic granite forms the foot- wall, gneiss the hanging, although at several points they seem to shade into each other. About nine miles west of Georgetown, McCiellan Mountain is located, immediately opposite Gray’s and Torrey’s Peaks. On the western slope of this mountain, the Baker and other mines are located ; on the east- ern, the International and Belmont. The Internatiopal. strikes about north 30° west, and is a contact-vein between gneiss on the north and granite on the south side. Its location, about 500 feet above timber- line, causes the ore to be frozen almost constantly; while, on the other : a: are. ee EER tice kes) ane : ‘eh, PLATE VIT:' ¢ =) ISN M N Burleigh Tunnel Tunnell 1147 fe. Marshall expucy.] GEOLOGY—INTERNATIONAL AND OTHER MINES. 299 hand, it has the benefit that provisions can be kept in the mine for months without deteriorating. Between walls that are well defined the vein is 5 to 6 feet wide, dipping from 12° to 20° to the north. A considerable quantity of ore is taken out of this mine, and trans- ported down the wagon-road by axle. It is mostly galenite, with spha- lerite, some fahlerz, pyrargyrite, and native silver. From the east a tunnel has been driven in on the vein, about 140 feet in length, and there by overhand and underhand stoping ore is being taken out, while the driving of the tunnel continues. Parallel to this lode, and appar- ently similar to it, is the Belmont, situated a short distance to the north. Besides these mining-operations, two great tunnel-enterprises have been undertaken, and are still being carried on. The one is the Mar- shal, the other the Burleigh tunnel, sections of which are given on the accompanying plate. (Plate VII.) The Marshal tunnel, pushed to its present state by the energy of General Marshal of Georgetown, is located on the southern slope of Mount Leavenworth, a short distance below the mines spoken of before. It is driven at a course of north 43° west, and has continued in a straight line. The proposition is to drive through Mount Leavenworth, strike all the lodes which it would cut at some angle, and thus let the tunnel serve to facilitate trans- portation of ores and regulation of waters. At the time I visited it, the work had progressed to a distance of 1,147 feet from the mouth, and a careful] section was taken. At 175 feet from the entrance, the first lode was struck, crossing the tunnel at an angle of about north 69° west. This is the Bulldog, or No. 1; contains a small amount of black blende, not sufficiently rich to yield any pay. Thirty-six feet of loose gangue-rock (b), quartz, and de- composed feldspar follow the narrow vein of ore, and a selvage of clay more than 2 feet in thickness separates this lode from the following gneiss. Arriving at 234 feet from the tunnel, lode No. 2 is reached, dipping off to the north, bordered on the north side by porphyritic granite (a), 20 feet in thickness. Following is a long stretch of gran- itic gneiss, with several slides dipping to the north, the rock being partly decomposed, partly sound. In several instances white mica oc- curs in this gneiss locally, but the black always predominates. Six hundred and ninety-five feet from the mouth of the tunnel, a lode was cut, supposed to be the Equator, and the strike approximately corre- sponded with that of the Equator. Two more veins follow at intervening distances of about 20 feet, edged on the north by granite of 25 feet thick- ness. Vein No. 5 then set in, followed by 8 feet of gray quartzite (d), and then by 22 feet of a light-gray compact porphyry (¢), which strikes parallel to its course. After this 73 feet of the granitic gneiss follow, when vein No. 6 is cut, at a distance of 880 feet from the mouth of the tunnel. The north wall of this vein is formed by 46 feet of hard por- phyritic granite (@), identical with that of other localities. From the end of this portion of granite to the present terminus of the tunnel at 1,147 feet, the rock remains granitic gneiss, with local accumulations of mica or quartz, changing the character somewhat. Two more veins were found, and 20 feet from the end of the tunnel a third occurs, strik- ing across it. These nine lodes that are thus cut by the tunnel contain more or less blende, more rarely galena, and as far as could be ascer- tained neither fahlerz nor pyrargyrite, as the veins higher up on the mountains do. Differing from this is the Burleigh tunnel, situated northwest of Georgetown, at the base of Sherman Mountain, about half a mile east of the Terrible. In June, 1873, it had reached a length of 1,490 feet, a Pi 300 GEOLOGICAL SURVEY OF THE TERRITORIES. considerable portion of which was driven by hand. The tunnel is wide, well graded, entering the mountain in the course of north 20° west. At a distance of 797 feet from the mouth of the tunnel, a dike of porphy- ritic granite occurs, 38 feet thick, (Plate VII, a,) striking at right angles to the course of the tunnel, with a southerly dip. Contact between this granite and the following gneiss is a vein striking parallel with the former, containing a body of blende 18 inches in thickness. From that point to the end of the tunnel,no further veins have been cut. About 450 feet from the end of the tunnel, a break occurs in the gneiss, parallel in dip to the porphyritic granite; a smali vein of quartzite, 4 feet thick, is found about 320 feet tarther toward theend. At the east- ern end of Georgetown, the Eclipse tunnel has been driven in a south- _ erly direction; it is claimed quite lately, with good success. From the few words that have been said about the working of the Georgetown. mines, it will have become evident that the plan of opera- tions differs slightly here from that followed at Central. The silver- miners of this section usually drive a tunnel into the side of the mount- ain containing their lode, and, having reached it, sink a shaft. At the level of the tunnel, drifts are made, and the ore extracted by means of overhand stoping. Sometimes a shaft is sunk from the surface, con- necting with the tunnel or one of the levels. A number of works have been put up in Colorado to smelt the lead and silver ores from this and other regions, the greater portion of which are doing well. Eventually the concentration of ores will have a regen- erating influence upon mining and smelting enterprise, if the flush pro- duced at present by the extraction of large masses of rich ore should pass away. JP ANI aU ILE IE. High up in the mountains of Boulder County, another district of silver-mines remains to be commented upon. Caribou is the mining camp, located in the center of a number of mines that have attracted con- siderable notice. Situated near the timber-line, with snow within three minutes’ walk from the hotel-door in the latter part of June, the report of rich lodes has attracted several hundred miners to the spot. As my time was very much limited just then, I can only speak of the two main lodes which I visited, and must again refer to Mr. Marvine’s report for notes on the geognostic formations. Predominating is a granite, with accidental admixtures of hornbiende, so that at certain localities it may be termed a syenitic granite, and it is therein the Caribou lode is located. The strike of this lode, that a short time ago was sold to a Netherlands company for $3,000,000, is almost due east and west, and it has a dip to the north that on an average is slight—in one or two points increasing however—never varying more than 20° from the vertical. Entering above, the dip to the north is found to be about 20°, continuing for 40 feet ; then follow 70 feet almost vertical, and after that a northerly dip of 15° again. With increasing depth the vein grows wider, so that it is 14 feet thick between walls at the depth of 210 feet, while it is 4 feet at the surface. Both walls are beautifully defined, having an almost polished appearance. On the north wall, the granite seemed to be of a different variety, but it could not be decided with certainty in the mine. A thin clay selvage sepa- rates the vein from either wall. In the distribution of the ore, a sym- metrical arrangement may be observed, ore being found near either wall, and again in the center. it consists mostly of galenite, sphalerite, argen- ENDEIeS GEOLOGY—CARIBOU LODE. 301 tite, pyrargyrite, and native silver; quartz mainly forms the gangue- rock, small amounts of feldspar also occurring. One of the western levels shows a very curious dike of granulite of 12 feet thickness, run. ning across the vein at a right angle, without occasioning any disturb- ance or dislocation, however. The Caribou is intersected by the No Name on the east, and the Seven-Thirty on the west side, at an angle of about 30°. In both these interesting lodes, the ore is of a similar char- acter, and they show no dislocations. Of minerals the following were found: galenite, sphalerite, argentite, in small crystals and massive; fahlerz, massive; pyrargyrite; native Silver, in wire form and leaf form; chalcopyrite, cerussite, and mala- chites ; the latter two as the result of decomposition. Two shafts are sunk on the lode, connected underground by levels and drifts, and at present a tunnel 700 feet in length is being driven in from the north to strike the vein. This will greatly facilitate the ex- traction of ore. Thus far the greatest depth reached in the mine was 370 feet. The No Name lode, striking north 20° east, intersects the Caribou east of the shafts, showing a considerable dip to the north. Walls are well-defined, granitic, and the thickness of the vein between them from 3 to 6 feet. Galenite and sphalerite, with argentite and fahlerz, con- stitute the main body of ore. Besides these minerals, chalcopyrite, wire-silver, cerussite, azurite, and malachite are found. At the time of my visit, a depth of 117 feet had been reached. A large number of other lodes, highly spoken of, were being claimed and opened at the time, but the expected opportunity of visiting the place in October again did not afford itself, and no information regard- ing them has reached me. PAC Eulune la Vie Annexed is a report of Dr. A. C. Peale’ upon the mines which he visited during the summer of 1873, and he has kindly permitted his notes upon them to be placed in connection with the above report. MINES NOTED BY THE SOUTH-PARK DIVISION OF UNITED STATES GEOLOGICAL SURVEY, 1873. By A. ©. PEALE. TARRYALL CREEK. There has been considerable mining done along Tarryall Creek, but at present little work is in progress. One great disadvantage is the scarcity of water. It is only during the spring and early summer that there is sufficient water for mining purposes. Above Hamilton the gravel rests on sandstones for the most part, and is from 10 to 20 feet thick. The following are two of the principal claims: Tarryall, Hubbard, and Snafferd.—They have two fiumes, the average 302 GEOLOGICAL SURVEY OF THE TERRITORIES. yield being from $5 to $6 per day. There are four men working, at from. $2.50 to $3 per day. Little French, or upper claim, has two men working on it. Near Hamilton there are two claims, worked by Hawkshurst & Foote. There are five men working, at $2.58 and board per day. The average yield is about $100.per week. While I was there they cleaned up $75. for five days’ work. In 1860~—65 there was in Hamilton a population of about 5 ,000 inhabitants; to-day there are not more than about half a dozen families. SILVER HEELS MOUNTAIN. The fellowing-are some of the lodes that have been opened on the mountain : Uncle Sam lode—The erevice is 8 feet in width and dips to the north- west. It was discovered in 1868 by Sargent & Greene, who are still its owners. But little work has been done. The gold and silver are found associated with pyrites in a quartz-gangue. The walls of the lode are gneissic. The ore is said to assay from $10 to $45 to the ton. Black Eagle lode—F¥our-foot crevice discovered by Hawkshurst & Foote in 1867, who,still hold it. Associated with gold and silver, mag- netic iron and pyrite are found. It is said to assay from $100 to $600 | to the ton. The lode is in gneiss, and dips to the southeast. Other lodes are the Black Warrior, Republic, Slater, and Mineral lode. Very few, if any, are worked. In the Republic, the ore is galena. The general angle of dip of all these lodes is about 30°. FAIR PLAY, COLORADO. Further notes in regard to the mines in the vicinity of Fair Play than are given below will be found in Dr. Hayden’s report. Placer-mining was formerly carried on very extensively on the South Platte River, and on all the streams tributary to it rising in the range that lies be- tween South Park and the Arkansas River. In almost all the guiches we may find the ruins of what were once active and thriving towns. There is still some mining going on on the Platte. The gravel on the river opposite Fair Play is about 70 to 100 feet in thickness. There are several claims being profitably worked here.’ The principal mining interest, however, centers in the silver-bearing limestones of Mount Bross, Mount Lincoln, and Horseshoe Mountain. The following section of Mount Bross was made by Mr. Stevens, of Fair Play, and shows the geological position of the argentiferous belt. The section corresponds with the illustration shown in Plate XY, (map). 1. Gneiss. 2. Yellow quartzite and sandstone, about............ 400 feet. Sabine limestones “eee iene Cape ess OU Oa ] 4, Light-colored limestone, 100 feet.....-..--.......-- - 350 feet. 5. Blue limestone.-_.... Be Se Oy oy MORE NER Wie mE PRS to Ga QU artzabe 40 klk 0 Ls Qe Re Mirena alte Se ere 10 to 20 feet. TU RIE eM eu Moki Ss tN Sic ua a RL al RAS eG 100 feet. 8. Black quartzite slates... 0249-2 224.2265: 2 Yeas ek a OE SANG S COME HE ep Me casi Se a a aa a REED i 15 feet. DE 1 aire Se AE ih hl a zane talline cpa AC) TE 200 feet. aly TAMA SS TOME sy eke ice Seki see cael ety ay cH MCAUEY Aha 20 to 30 feet. AL SATS COME Hee aie ti take Coke sd Vechten eye str es 150 feet. BN hs hake lays oy ella oi ay A SUP UN 0/52 lathe ela cv ASS alte eet as Ute cee 500 to 600 feet. PLATE. X P. an: ek hanes XA \ LATS: 3 \ \ IG / N= N ———— ee iv = 33> eel ss NES itl] i i ay il \ | ——4N=' NN ——— / =N=\y <<“ | f "N= =: RRRY Eade ‘ : =k Vw, = i SS | ‘’ eS = 7 2a SS MMs = ji al I (= al \ t : _ / / si | ; Not Aa ae | f 4 \ ; * SSS UY chal SS SS SS i] \ a a S SY f My WN ei NeW alks S i / 4 la) / ) “ ~ \ FA A , \ i Yaa 4 \ hy ee Bibs gic t aw GN es oe \ / ‘ ae ¥ f / \ UY Fee Ae NY rn Men Vie { | \ y | » aes \ ae ’ / Lig | L me Ui, *. 4 ‘\ ‘ \ f \ Ye : coat eee \ Cer Bearing Blue imestoue Limestone l = cone PLATE.XY. Ui) {LEED eS eee \ 2 ST ZZ Se SS ( ISNS PETTY | ll } ii a = - 2 ~ i x _— Tee | me A. My YH Yy Af fy 4 . i Blue GEOLOGICAL MAP . cai Bt faeise i of the Limestox 7 MT. LINCOLN ACM WLLL Mining Region f spine 5 i rie MERE 5 ey uci ? Kf it Na rein eeneaeeton ey mg me = ae 2 f 4 : f RE ESRD ena me vies - Pig Ys t Pesan cot ee ees ie i RPE Se ae tages i ¥ ni i , te ae py eae | / : - ra Apr ean rape ican aA ijinmsnaviertine a i" 7 ei) k vaaesanpsumareranss IRS OR ARENT EN aaDuen) GEOLOGY—FAIR PLAY. 303 This last bed reaches to the summit of the mountain. It is in bed No. 2, which is probably the equivalent of the Potsdam sandstone, that all the gold, or most of it, in the region has been found, especially in the lower part, where there are d.kes of voleanic rock. The gold-mines of Mosquito and Buckskin Gulches are found here. All the sandstone contains gold, but not in sufficient quantity to make it profitable to mine. Itis in bed No. 4 that the silver-bearing galena is found. This limestone is lighter-colored than that on either side. It is probably a part of the Quebec group. The ore occurs in segregations and impreg- nations, and, as far as has been ascertained, is confined to the belt of limestone represented by bed No. 4 in the section given above. The accompanying map or diagram was made by Mr. Stevens, who has kindly allowed me to use it. It is not drawn on an absolutely accurate seale, but will give a good idea of the various claims on Mounts Lincoln and Bross. The principal ones are the Moose, the Baker, and the Hia- watha. Theore, as has already been intimated, is galena, which, accord- ing to the assays of Mr. Peters, carries from $3 to $200 in silver and as high as $120 in gold, the coarser-grained galena always being the richer. The gangue of all the mines in the limestone is barytic, both in massive and crystallized form. The mines at Horseshoe Mountain are similar to those of Mount Lincoln and Mount Bross. They occur in the same belt of limestone, and their mode of occurrence is the same. The ore is taken to smelting-works at Alma and Dudleyville, near the base of Mount Lincoln. : ORO CITY. Oro City is at the head of California Gulch, a branch of the Arkansas River heading in the Park range. California Gulch has been the seat of extensive placer-mines. At present, however, very littleisdone. There are three or four claims being worked near Oro. The principal mining, however, is done at the Printer-Boy lode. The following notes were obtained from Mr. C. L. Hill, superintendent. The mine, of which a diagram is shown in the illustration, is owned by the Philadelphia and Boston Gold and Silver Mining Company, (J. Marshall Paul, of Colo- rado, and H. M. Paul, of Philadelphia.) The discovery was made in 1868, but no work was done until 1869. It was first worked by a company in 1870. As shown in the diagram, there are two shafts, a main one, 275 feet in depth, and a boundary one, 145 feet deep. These shafts are 367 feet apart, and between are two levels. Above the upper one there is a third level. From November, 1872, to the latter part of Sep- tember, 1873, $75,000 was taken out; the average yield per week be- ing 100 ounces. In September twenty-six men were employed, at $3.50 per day. The company owns a mill near the mine. The expenses of mining and milling per week are $800. Besides the Printer-Boy, there are the American Flag and several other lodes at the head of Califor- nia Gulch. HOMESTAKE LODE, ETC. The Homestake lode is situated at the head of a small western branch of the Arkansas River, west of Tennessee Pass. The district is called the Homestake district. There is a small settlement, to which the name of Lake City has been given. It is just at the timber-line, which here is about 11,500 feet. Besides the Homestake, which gives its name to the district, there were at the time I visited the place some forty claims, very few, however, of any importance as yet. This lode was discovered in July, 1871, by W. A. Crawford and 304 GEOLOGICAL SURVEY OF THE TERRITORIES. two other men, while trying to find a trail across the range. It was. first worked in September, 1872, by Archer & McFadden, the present owners. The lode strikes south 65° west; dip, north 25° west; angle, 75° to 85°. Two levels were commenced in the fall of 1872. The east level, in September, 1873, had penetrated 150 feet. It is 54 feet high, 4 feet wide at the bottom, and 34 feet at the top. It is propped with timber, being but 30 feet below the surface. The lode is from 2 to 3 feet in thickness, and is in gneissic rock. The west level had been carried in 150 feet, and the average width of the lode here was 2 feet. This level penetrates the solid rock some distance below the sur- face, and propping is rendered unnecessary. Below these levels, two tunnels have been started to strike the lode., One is 100 feet beiow, and the other 300 feet. Assays made by M. M. Hayes, assayer, for the Homestake district, vary from $100 to $800 to the ton. One picked Specimen assayed 738 ounces to the ton. The ore is principally argen- tiferous galena in a gangue of baryte and calcite. There is also a trace of gold. The complete list of minerals found here will be seen in the catalogue of minerals. In September there were nine men employed, at $3.50 per day. From Mr. J. A. McFadden, one of the owners of the mine, I learned that the expenses from May to September, inclusive, had been something over $3,000. This included building of cabins, supplies, &ec. The mine having been just opened, of course the expenses were heavier than they would be afterward. Up to September, 30 tons of ore—about half the quantity taken out—had been shipped to Denver. ARKANSAS VALLEY. On the Arkansas River, in the vicinity of Granite, there are quite a number of placer-diggings, and also in Colorado Gulch, one of the west- ern branches of the Arkansas. During the season of 1873, there were two or three claims worked in the latter place, yielding about $5 per day to each man. This gulch, in 1863, was one of the richest in the Terri- tory, yielding $75 per day to the man. ELK MOUNTAIN DISTRICT. This is a new district in the Elk Mountains at the head of Rock Creek, and little has been done beyond the locating of claims. There are about thirty claims situated on the south side of Rock Creek. The discovery was made in 1871 by Messrs. Brennan, Brant, Graham, and others, but nothing was done until1872. The lodes are all in the beds of Cretaceous age—black metamorphosed slates, containing quantities of Inocerami. The following are the principal lodes : Buckeye—This lode was discovered July 29, 1873. It is from 5 feet to 6 feet in width, and dips 12° south 35° east. It is well defined for at least 1,000 feet. The one is principally argentiferous galena, associated - with pyrite, cerussite, chalcopyrite, malachite, and a little hematite in a quartz gangue. Blow-pipe analyses, made by Mr. Kirker, yielded 7) to 100 ounces of silver per ton. D. P. lode—This was discovered July 29, 1873. It is 4 feet in width, and its direction is southeast and northwest. Ore and gangue as in the - Buckeye. Fair Play.—The discovery was made July 20, 1872.. Its width is about 6 inches. ‘The ore is similar to that in the other mines, and is contained in a gangue of quartz associated with calcite. Liverpool—This lode was discovered August 1, 1872. It is 2 feet huet. bm be + #7hk ae ‘A ghy gk a 4 i Te Tie «) tM Py Stare peered Hat np oe a en ae . My » Mae: abet ee - * 4 : Vo ee ’ Uh Poe ji ahoyd sits Ves & ~ oie, Aarne bh mie Sh iow ee, — naorne tema = sn Sheet Showing the adwision of the Destrict as used tn the Fleport and atsa the conventional Signs usex ~en the G ealogecat Secleg7s . SECTION White COP TES Yellon Fedl Cor lorerute VEX WULY, Wate a S Fernie Sse Grads > & Grez y Dolomites Dark Shales aaa GEOLOGY—ELK MOUNTAIN DISTRICT. 305 wide, and its direction north 55° east. In all other points it resembles the other lodes. ‘ Rover State-—Discovered July 24,1873. Its width is about 2 feet and strike north 65° west. Connecting this lode with the Pacific, there is a smaller one, 6 inches wide, called the Sidney. Pacific.—This lode was discovered in July, 1872. The strike is east of south. It has seams of different widths. The ore has assayed by blow-pipe about $10 per ton. Helenu. This lode was located in July, 1872, and is from 6 to 8 inches in width ,striking north-northeast and southwest. Cape Horn.—This lode is from 10 to 15 feet in width, and has been tracedm ore than 1,000 feet. It strikes north 65° west, and dips east of north at an angle of about 75°. .The ore is said to assay 150 ounces per ton. Connecting the Cape Horn with the unr is the Hrie, about 6 inches in width. Anna and Washington.—The Washington lode is a continuation of the Anna, the extent of both being 3,000 feet. The discovery was made July 25, 1873. The strike is north "550 west, and the dip southwest. It is in a very black shale, and between it and the Cape Horn there is a bed of quartzite. The width is about 5 feet, which increases in places. The ore is of the same character as in the other lodes. Mr. Kirker, one of the company owning the claims, assures me that as far as he has traced the lodes, they seem to converge toward the Anna and Washing- ton. He says also that west of these there is another set, of which the following are the principal ones: Montreal, 15 feet in width ; Bear Hole; New Chicago, 3 feet wide; Deen Hole, Al foot 6 inches; St. "Louis; Wisconsin; Superior; Tempest; "Lily; Hoosier; Lookout; Cashier and Silver Wing. These, he Says, seem to converge toward the Montreal, as those in the other group do toward the Anna and Washington. All the lodes are owned by the Rough and Ready Company, composed of the following members: R. A. Kirker, William Gant, Samuel McMillen, Benjamin Graham, Louis Brant, James Brennand, and C. M. Defabauch. PC reASE eu Lele. REPORT UPON BHE GEOLOGY OF THE SAN LUIS DISTRICT. Section a —The district assigned to the San Luis division for topo- graphical and geological survey for the summer of 1873 is bordered on the north by a line running east to west six miles south of Pike’s Peak, on the west by the one hundred and seventh meridian, on the south by a line running east to west twelve miles south of Sag euache, and on the east by the eastern slope of the Front range. It can be appropriately divided into three sections, as shown by the accompanying diagram. Section a, comprisiug the northeast portion of it, separated on the west, southwest, and south from the others by the Arkansas River. Section b contains the southeast portion of the dis- trict, terminating westward with the western border of San Luis Valley, and from there northward with the well-known Poncho Pass. On the north it is bounded by the Arkansas. Section ¢ represents the remainder, the western part of the district. Along the eastern portion of section a we notice the heavy masses of mountains, cut by deep cations and gorges, showing that characteristic 204G8 306 . GEOLOGICAL SURVEY OF THE TERRITORIES. appearance that is imparted to any landscape by the predominance of archean formations. Westward from the edge of the great plains the mountains rise abruptly, particularly so in the vicinity of Pike’s Peak the summit of which is more than 8,000 feet above the valley. In the pure atmosphere of that region, the deception in distance allows the traveler to be even more strongly impressed with the grandeur of the scenery that has given the “ Pike’s Peak country” so much of its justly- deserved celebrity. Along the eastern border of these mountains, where they gradually taper off into the plains, stretched for many miles before them, the sedimentary beds reclining against the granitic mount- ains have at times been greatly disturbed, and now form at several ° points very grotesque groups along their base. Going westward from the border of this Front range, more into the interior of the mountains, unmistakable cones appear, denoting former voleanice activity, changing with their introduction the general aspect of the country. Instead of densely-wooded hills, covered either by living or dead timber, areas of grazing-lands are frequently found, fre- quently alsomarshes. In many cases the prominent cone-shaped peaks, the probable points of voleanic outflow, present a more desolate appear- ance, being covered with innumerable fragments of rock, rarely large, but sufficiently so to prevent any extensive growth of vegetation. A variation from this general character of the country occurs along Oil Creek, where a comparatively low tract of country extends northward for the distance of about twelve miles, with a width varying from two to four miles. To the west of this little valley the granitic rocks are no longer the predominating, for the volcanic increase so largely in bulk and extent as to change the face of the country. High, grassy plateaus appear, differing in vegetation to such an extent from the older rocks that may be outcropping that this difference alone may frequently fur- nish useful hints to the geologist regarding the distribution of the formation. Quite frequently the creeks have worn deep, rugged ravines, although it would undoubtedly be erroneous to attribute all the canons and gorges to erosion exclusively. Farther toward the northwest, the character of the country again changes; it becomes more rolling, sup- plied with frequent cones; the valleys are broader, less deep. In the western portion of section a, the mountains are no longer so high, and their slopes are more gradual on the northern side, although often quite rugged on the opposite; the influence pf comparatively little disturbed sedimentary formations is perceptible. _ Bordering upen the Arkansas, the hills of this western portion are less massive—less so than those farther east—owing to the lower relative and absolute altitude and consequently smaller depth of the canons. Granite forms the heaviest masses of section a, although not covering the greatest area. On the western part of the section it occurs as the main rock, presenting a dark-red or brown color, showing but little vari- ation in the character of its texture and structure, and usually weath- ering in heavy bowlders; it frequently forms bold and prominent faces on the mountains. Toward stations 89, 90, and 91, it is mostly covered by the overflowing trachorheites, outcropping only in the deeper cations and gorges that are in a great part due to erosion. Owing to its coarse texture, it readily decomposes, but, dependent upon the more or less accidental percentage of its constituting minerals, does not decompose uniformly throughout. At station 95, the granite becomes very coarse- grained, so much so as to show a perfect separation of the three min- erals, feldspar, quartz, and mica; only the latter, however, follows its inclination to crystallize. At this locality, the feldspar (orthoclase) ig of pape ones!) Urea w “py aang * sil a toi fete eed att Hus ro a4 sir wi ry os} er i seve’ D Liss V4 f, x ( D Mj a i hl Wy as Wi bi) yA f pA Mpa ld WH € 5 lla ( ZY ji Uf I % WT: (Ci rf Lg iy Lp) CU IK. | pL, Intersection of views. yxpuce.] . GEOLOGY—SAN LUIS DISTRICT, SECTION A. 307 a bright-red color; the quartz, yellowish or white; the mica, gray to brown. Another point where the granite assumes a similar character is immediately west of Caiion City, which may perbaps partially account for the deepening of the steep caton from which that city has derived its name, This cation forms the bed of the Arkansas River for a dis- tance of about six miles. Station 11 is located directly north of this canon, in an air-line about three-quarters of a mile distant, and about 2,000 feet above the river-bed. Allowing all due consideration for the immense effect produced by erosion, it still seems improbable that the Arkansas should have forced its way through almost six miles of solid granite, when a slight deviation to the northeast would have afforded it a by far easier passage, unless some existing favorable condition induced this course. It seems reasonable, and warranted by the facts observed, to suppose that, by some agency or other, possibly by the grad- ual rising of the granitic area and consequent cracking or splitting of strongly-tensioned portions of it, some facility may have been afforded to the river in shaping its course. This view may receive some support in the fact that the line pursued by the Arkansas through that section of granite is a comparatively straight one. The suggestion that the river may gradually have cut through during the continuation of the rise along the fermer coast cannot be entertained, because at the time before that took place the now Cretaceous portions must have been so low as to compel it to flow out over the area they at present occupy. To the northwest of station 11 the granite is mostly covered by the trachorheites, and only exposed in depressed localities. Along the Arkansas, westward, toward station 10, it maintains its character, wea- thering in more or less angular masses. At the west side of the bridge built across the river, a short distance south of station 10, is stationed an isolated granitic sentinel, dark red or brown, with a very large per- centage of feldspar, but little quartz, and still less mica. This monu- ment-like rock shows a pretty illustration of the intersection of two veins; a narrow quartz-vein running up and down has been broken and displaced by a broader younger one, crossing it at an almost right angle. Speaking more correctly : the two halves inclosing the smaller vein have beeu displaced by the formation of a broad fissure, in which the mate- rial composing the younger vein was deposited. North of station 10 granite mainly crops out in the valleys, as in those of Currant, Cotton- woed, and Tallahassee Creeks, the beds of which are mostly formed by it. Proceeding in this northerly direction, we find the lithological char- acter of the granite undergoing some change; the feldspar more fre- quently shows yellow and flesh-colored tints instead of the red and brown; the quartz turns from brown and reddish to rose-colored and yellow, even gray and white; black mica begins to predominate over the white, gray, and brown. At the upper end of Cottonwood Creek, near station 68, the texture of the granite begins to resemble closely that of gneiss, and this change is carried out also in the appearance of weathering, although it characterizes no newly-entering formation, but merely an increase and accumulation of the micaceous constituents. North of this station the granite widens out, being exposed over larger areas as the trachorheites recede. West and southwest of station 10 it forms lower hills, considerably cut by the drainage. The western por- tion of section a bordering on the Arkansas is formed by granite again, appearing this time it a strip of about twenty-four miles in length and three to four miles in breadth. It is coarse-grained, and very similar, if not identical, with that of the eastern half of the section. Distributed throughout its southern half, although not occurring frequently, are 308 GEOLOGICAL SURVEY OF THE TERRITORIES. small patches of fine-grained granite, distinct sometimes not only in their texture, but also in the character of. their constituent minerals. A granite found near station 59 showed gray quartz, white feldspar, and black mica; was very fine-grained and compact. On Badger Creek, a short distance east of station 58, a small patch of porphyritie granite crops out that shows differences of texture within a very limited dis- tance. It contains oligoclase, orthoclase in Carlsbad twins, gray quartz, black mica, and chlorite. In the southern and western part of section a the granite is frequent- ly traversed by dikes of hornblendic rock, resembling to some extent diorite. Although they will be spoken of under-the title of “dikes” hereafter, they form a very characteristic feature of the granite, and as such must be mentioned here. Distribution.—Immediately at the eastern slope of the Front range the granite begins, extends westward to station 91, and a few miles beyond stations 93 and 94, bordering the east side of Oil Creek Valley. At the northern boundary of this valley it sets in again, separating two large voleanic areas by a band of three to six miles in width. West of Oil Creek it is found in all the deeper cafions, while trachorheites cover the high plateaus. Along Currant Creek it is exposed in a strip from one and a half to two miles wide, increasing this width toward stations 71 and 72. The greater portion of Cottonwood Creek runs in granite ; also a part of Tallahassee Creek. On the Arkansas, granite appears again about half a mile west of Canyon City, and continues westward to sta- tion 6, with a single interruption opposite station 10, where Cretaceous rocks form the bed of the river for a short distance. Small patches of it appear at stations 58/, 58, and 57. West of Badger Creek several such patches occur. The second extensive mass of it runs approxi- mately parallel to the Arkansas, forming its eastern bank. From sta- tion 52 southward it continues until a point is reached within two miles of station 5, where the volcanic rocks cross the river. Resting immediately upon the granite, we find the Silurian character- ized by but a few fossils and the well-known quartzitic formations. From a distance these beds, situated in the western portion of section a, may easily be mistaken for the prevalent trachorheites, as they form steep, although not high, bluffs, rising abruptly from the granite, capping some of its highest points along a line of about 15 miles. Their quartzitic constitution allows them to resist atmospheric influences for a greater length of time than the under and overlying rocks, so that, taking all these points into account, they form a well-defined character- istic horizon. At times the rock partakes more of the character of a limestone, but in that case segregations of siliceous matter, mostly in the shape of chalcedony and hornstone, ‘afford a welcome lithological feature of distinction. Wherever the Silurian formation occurs in sec- tion a, it conformably underlies the Devonian and Carboniferous as far as could be, ascertained. Beginning in the northwest corner of this section, we find a narrow strip of strata belonging to the Silurian period, running from about one mile north of station 3, “down i ina southeasterly direction, until it reaches the Arkansas, forming by its course the ap- proximate representation of alargeS. At station 53, which is located — on a dark-gray limestone, with hornstone sesregations, ascribed to the Silurian, the strata dip at an angle of 9° to 12° almcst due east, gradu- ally lessening the degree of their dip as they extend eastward. ) oo HOW yd; i) ag bet wit Fu aeweY Bre la Die fore PTS) bas td Pat that Loy (PMTRES ay: Mee tha mathe & SSS eae = ~ eae Winetiee, At f, | io i Oe ea OE We Raa pecavered bs Para, Be citer epee ae eee ee es mein REY IED THE ‘at the Gigli: DPPOSNCE Ot be A aay iaiay Te Mier J Eayaks “tty: Sagar Mor eaen ae) aes RH ietterss Mibishs Wie coe | PLATE. XM. nner GEOLOGY—SAN LUIS DISTRICT, SECTION B. 327 brown argillaceous shales and isolated strata of limestones, (e,) with fossils. Near station 19 one of these was exposed, and ecrinoids were found. The remainder is made up again by Arkansas sandstone and a few limestones, all Carboniferous, the combined thickness of which, with those underlying, probably exceeds a mile. Although it was pos- sible to see over to the east side of the slope for some distance, but little detail could be observed, and the section, therefore, shows nothing but the lower strata. The course of the section is about north 76° east. Proceeding farther northward, to station 20, it was found (Plate XIII, section B) that the granite (a) had again appeared, and forms the highest peaks at that locality. As far as could be determined, the Arkansas sand- stone () rests upon the granite for about 2,000 feet, although I have but little doubt that it is underlaid by still older formations even at that point, but the amount of débris that is deposited at the base of the mountains obscures the line of junction. In ascending the west slope to reach station 20, the boundary-line between the granite and sandstone was found to be well-defined, the latter ending with a little swell in the outline of the mountain. At that point its dip is almost vertical, but soon diminishes; a section may serve to illustrate the conditions observed. A heavy bed of dark, almost black, shales (d) overlies the sandstones, and is in turn covered by a series of sandstone strata, (b.) Toward the base of the mountains some limestone makes its appearance, slightly disturbed, but originally conformable with the sandstone. The eastern slope is mainly composed of the latter. In speaking of this station, 20, it may not be out of place to mention a phenomenon which, although not strictly appertaining to geology, may be of some interest. During our trips in the higher mountains we had several times noticed evidences of the presence of comparatively large quantities of electricity, but on this station anything thus far experienced was surpassed. It was found that as soon as a sufficient amount of electricity was contained in the atmosphere, any metal instrument or weapon that may have been about would produce a buzzing sound, like the hammer of an induction-coil. When the supply of electricity in the lower strata of air was exhausted and the buzzing ceased, it could be renewed by holding the instrument up higher into the air. On this particular instance, a heavy gale was blowing from the north, driving a storm toward us with great rapidity. The wind came in single puffs, and while a rifle that was carried along would not buzz during the short lull of the wind, it would do so quite strongly as soon as the gust reached the point of observation. At one time the quantity of electricity grew so large and intense, that I received from my rifle a shock sufficient to paralyze me momentarily. The weapon dropped out of my hands, and about half a minute after a discharge of lightning took place very near by, by which the electric phenomena were quieted for a time. Soon, however, electricity accu- mulated again; its manifestation again became intenser, until every hair on the head was rising upward ; every finger buzzed when held up into the air, and every pointed rock hummed with a sonorous sound. As soon, however, as the next discharge took place, this time some dis- tance off, itagain subsided. From personal communication it has been found that these occurrences have been noted by a number of persons, who perhaps either had no opportunity of making them known, or deemed them of too little importance. As the diluvial and alluvial material begins right at the basis of the west slope of the range, it could not be determined with certainty whether the Carboniferous strata extend to the westward for any con- siderable distance ; but about eight miles west of the termination of the 328 GEOLOGICAL SURVEY OF THE TERRITORIES. sandstone it crops out again, leaning up again at Granite, on the west side of the valley, with a dip to theeast. It is very probable, therefore, that the Carboniferous strata extend across that northern end of the San Luis Valley. This western outcrop is small, about five or six miles in length, but very narrow, dipping gently under the diluvial deposits. East of Mosco Pass the sandstone seems to extend across the lower por- tion of Wet Mountain Valley, as it was found a little west of stations -83 and 84, on the western slope of the mountains, and the aspect of the valley at that place indicates a crossing of the sandstone. Limestone accompanies the sandstone at several places in a long patch west of station 19, dipping conformably with it, with the exception of one small local fold ; but besides this occurrence there are several beds of limestone, interstratified with the sandstone, one of which afforded a few fossils. On the western side of Homan’s Park, where the sandstone crops out again, limestone is also found with it, analogous to the limestone of section a, overlying the Arkansas sandstone. In connection with this formation I have to mention a very peculiar conglomerate, found only once at a high elevation. The Christones, upon the highest of which station 17 was located, are entirely composed of a conglomerate, con- taining fragments of granite, gneiss, hornblende-rock, mica-schist, pink porphyry, garnet-rock, epidote-rock, and quartzite. These fragments are not rounded by action of water or atmospheric influences, but have perfectly sharp, angular outlines, and are cemented by a hard, gray quartzitic paste. Their size ranges from half an inch to several feet in diameter. In weathering they resist longer than the matrix does, thus studding the almost perpendicular walls of the mountain similar to the ornamentation of Gothic spires. A little south of station 17 a dike of pink porphyry has broken through the conglomerate, and makes its appearance near the top of a peak. Stratification can be noticed to some extent in the arrangement of the conglomerate, and the strata dip off very steeply to either side from the crest of the range. Besides these more cunnected masses of Carboniferous rocks, an isolated point of ex- posure was found near Boggs’s ranch, in the southeast corner of section b, where the rise of the main granitic body seems to have been sufficient to bring out this formation besides the Mesozoic beds. Itis of but small extent, identified by fossils found in the grayish limestones and shales. As in section a, the Carboniferous here, too, is succeeded by the Mesozoic formation. ~ On Plate XIII, section ¢, an ideal section through the Sangre de Christo range is given, showing at once all the various occurrences | throughout the entire range, and its general character. Resting imme- diately upon the granite are the Arkansas sandstones on either side, inter- stratified with limestones, (e,) and shales, (d.) Dikesof hornblende-rock, (f,) with a strike of north to south, traverse the sandstones. Toward both east and west the dip eradually decreases. As in section a, the Trias- sic and Jurassic beds occur along the eastern edge of the granitic Front range. Directly south of the Arkansas they begin, occurring in isolated patches all the way southward until Hardscrabble Caton is reached. From this point they cover more ground, until a short distance below Bogg’s Ranch, where they entirely cease. Statfon 78, southeast of Hardscrabble Creek, is located upon such a sandstone, of ‘dark- red color, lithologically identical with that farther north. The dip throughout is to the east and a little north of east, steeper at the base of the. mount- ains, more gentle nearer to the plains. South and southeast of station 78 they increase considerably in thickness, forming bluffs of nearly 1,000 feet in height. Deep gorges, at times narrow, sometimes wider, in the lat- Cote GEOLOGY—SAN LUIS DISTRICT, SECTION B. 329 ter case forming fertile areas are cutintothem. The shales, of a dark-red to a brown color, seem to increase considerably in thickness, and southeast of station 79 compose the soil of a valley that is well cultivated. As stated under the head of Carboniferous, a portion of this latter formation is exposed at the western ascent of this valley, indicating a more con- siderable rise of the granitic country immediately west than is found any- where along the old shore-line. White sandstones and single dolomitic strata interchange with the red ones, while those beds referred to the Jurassic formation seem to decrease in thickness. ni Bett: Hat wee Oe ore] GEOLOGY—SAN LUIS DISTRICT, SECTION C. o41 of those the preservation has been a rather inferior one. A number of crinoids, brachiopods, cephalopods, &c., were found. The aspect of several of the species reminds strongly of Upper Devonian types; but in determining here, the general character of things must be taken into consideration rather than the identification of any one single specimen be relied upon. Curiously enough, almost all the species found there are such as have very nearly allied forms in the formations preceding, so that discrimination becomes difficult. We have here a similar case to one that Professor Meek speaks of in the Report of the United States Geological Survey for 1872, page 432,in treating of the Carboniferous of Mystic Lake and vicinity: ‘They belong, without exception, to genera that are common both to the Carboniferous and Devonian, while a smaller portion of the genera is also represented in the Silurian.” ‘Some of the Producti, Chonetes, and Spirifer have rather a Devonian look, while a fine striated Hemipronites is very similar to some of the Devon- ian types of that genus.” ‘“ Notwithstanding the resemblance of some of these fossils to Devonian forms, and the fact that scarcely any of the species can be identified beyond doubt with forms peculiar to the Car- boniferous, I must regard the whole as belonging to the lower part of the Lower Carboniferous.” ‘The entire absence of any strictly Devon- ian and other types of corals, crinoids, lamellibranchs, &c., also favors the conclusion that this formation belongs to the Carboniferous, which conclusion is also supported by the specific affinities, if not even by the specific identity, of some of the species of Spirifer, Productus, &c.” This quotation applies admirably to our present case. We find— Numerous fragments of the columns of crinoids, not recognizable. Large numbers of a delicate rimose chetetes-like coral, which is mostly weathered beyond recognition of outer structure. An infundibular form of Menestella, quite numerous. Athyris, in one small specimen. Spirvfer, with the medial lobe finely striated longitudinally; the lat- eral lobes containing numerous stronger, simple, radiating cost; vary- ing considerably in size. Ehynchonella, which has a decidedly Devonian aspect. Orthis, a compressed resupinate form, with an extremely narrow area; probably a new species. Hemipronites, closely related to H. crenistria, resembling some De- vonian types. Goniatites, in two very poor specimens. Orthoceras. Productus, in two specimens, that admit of some doubt, however; one fragment was found that seems to belong to a conoid univalve. Mesozoic beds—None are found in section ¢. The Cretaceous formation is quite considerably developed near the cen- tral western portion of section c, following along Tomichi Creek. From the south and west, the predominating trachorheites have overflowed the sedimentary beds; and while a considerable portion is covered by them, erosion has broken through at several points, and thereby formed blufis from 100 to 300 feet in height, composed of sedimentary strata and capped by voleanic material. All along the western side of the valiey bordering on Coochetopa Creek this is the case, and on one of the bluffs station 35 is located. The greater part of the eastern portion of them seems to be made up of Cretaceous Nos. 2 and 3, while the western shows more of the lower sandstone strata. A section taken through a cut in a narrow gulch to be east of station 35 gave the follow- ing result, beginning from below: Be ' GEOLOGICAL SURVEY OF THE TERRITORIES. 22 feet, dark-gray shales, weathering a little lighter, containing Ostrea complexa and fragments of large Inoceramt. 40 feet, of yellow shales, with white and yellow sandstones, full of Ostrea and Inoceramus. 17 feet, of light-yellow shales, of more marly character. ° 8 feet, of the same shale, traversed by plates of calcite from one fourth inch to one inch in thickness, of several feet in extent. 12 feet, brownish-gray shales, also with calcite. 40 feet, of gray shales, weathering lighter. 120 feet, gray shales, partly dark, partly light, weathering rapidly, con- taining toward their upper and lower limits pyrite and erystals of selenite. 30 feet, of light-gray shales. 20 feet, of yellow shales. Above this there was rhyolite, having flowed from the southeast. This thickness, of little over 300 feet, probably represents the average thickness of the Cretaceous beds of that horizon throughout that valley, as but small deviations from the general character were observed. In going up to station 36, these same strata were found again; but how they connect I am unable to say. They certainly overlie the quartzite of that station, dipping in a southwesterly direction toward the valley. Sec- tion A, Plate XIV, will explain the relative position of the strata. It runs almost due northeast to southwest from station 36 to station 35. The trachyte (7) predominating on the western side of Coochetopa Creek comes toa close there, and along the bed of the creek a coarse-grained granite (d) crops out. Resting immediately upon it, we find a quartz- itic white sandstone, (e,) covered by light shales‘and shaly limestones ;, above these, another white sandstone; and then yellow shales with iso- lated sandstone strata. These latter are the shales referred to in the previous section, and it is they that are mainly covered by trachyte, (g.) A few miles north of station 35 they are covered by drift, and do not appear again until near the base of station 36. Whether the sand- stone there is conformable or not with the Cretaceous strata, or what- ever its stratigraphical conditions may be, could not be made out on account of the utter lack of any exposure of structural conditions. The next section (B) is taken through station 35 to station 88, having a course of a few degrees east of north. Here the strata can be more. readily followed, and it can be made out with certainty that the sec- ond sandstone stratum, (e,) probably even the first, bends upward again to the north, and reclining upon the granite, forms a shallow synclinal valley. The drift-material deposited “by Tomichi Creek is quite consid- erable, and hinders somewhat in recognizing structure ; but the yellow and brownish sandstone capping the granitic bluffs in the western por- tion of Tomichi Valley is probably Lower Cretaceous. In the eastern part, the dip is off from the trachorheitic mountains to the westward ; while from the western end, the dip is southeastward. Wherever the characteristic yellow and evay shales occurred, considerable quantities of fossils were observed, but, strange to say, never anything besides Ostrea and Inoceramus. Over westward, toward station 41, the shales have disappeared almost entirely on the northern side of the valley, and nothing but the lower sandstones remain. It seems probable to me that the Cretaceous rocks extend, at least for some distance to the south and southeast, under the covering trachorheites, judging from the general orographic features of the country, that seem to be more those of a sedimentary one than of a volcanic. The Cretaceous that we find along Tomichi must have come in from the northwest eae GEOLOGY—SAN LUIS DISTRICT, SECTION C. 343 in the form of a bay, and was probably driven back by the voleanic ac- tivity that was developed soon after south of it. About ninety square. miles are covered by this formation here; and if it extends under the. trachorheites as far as I think it probable, it will amount to about one hundred and fifty square miles more. Between stations 26 and 27 a small fresh-water deposit was found, undoubtedly belonging to the Tertiary period, and probably the Miocene. A section on page , illustrating the position of the eruptive volcanic rocks, will show its position. Rest- ing apparently upon granite, it dips off gently to the westward, contain- ing, in its strata of white argillaceous limestones and shales, numerous. remains of plants and smal shells of Limnea. The volcanic material coming from station 27 eastward covered the greater portion of theiittle bay, so that not much of it is exposed at present. . This oecurrence may be some small, merely local, fresh-water deposit, or it may be the continua- tion of a more extensive series of strata, which cannot be determined un- less the country is either very well known, so that additional exposures: might afford some reliable data, or otherwise artificial means of testing wouldbeemployed. Of thetwo, the former seems more probable, as some of the neighboring streams cut in quite deeply, down to the granite, so that any sedimentary rocks occurring there would have been exposed. This little outcrop is the only one of Tertiary beds that was found through- out the entire section, but.it seems probable, judging from the orographic features of the country, that west of our district we may find more exten- sive formations belonging tothatage. It may seem strange that along the center and consequently western terminus of San Luis Valley there is neither Cretaceous nor Tertiary, as the waters of that period could not have had any very great obstacles to overcome in reaching those points. The larger portion of section ¢ is covered by volcanic rocks belonging to the trachorheite group, which form a heavy mass of mountains, sometimes rising to a very considerable elevation, covering at the same tine over fourteen hundred square miles. In this main mass of trachorheites we find every variety belonging to the group represented. As arule, it may be said that the highest and most prominent points are composed of andesites and trachytes, the latter rarely, however; that the plateaus and terraces are andesitic, sometimes trachytic tuffs; the low, bluff-like hills along the base of the higher mountains are of a rhyolitic character; and a number of little hillocks are formed by an ashy material, probably not much older, if not as young, as the rhyolites. Discrimination from the lithological char- acter alone becomes very difficult wherever such an immense number of varieties occur. On every hill, on every station, several varieties of the predominating rock can be found, varying within twenty yards of each other to such an extent that it is by no means an easy task to draw the lines of distinction correctly. A mass of high andesitic mountains occurs about five to six miles south of Mount Ouray, upon one of which station 24 is located at an elevation of 13,400 feet, and throughout that portion of the volcanic country anumber of peaks nearly as high occur, forming an almost regular horseshoe, studded with numerous snraller hills inside. When seen in the field, the impression produced by it was that of one huge crater-edge, containing withinits limitsa number of smaller eruptive cones, Along the crest of that crater, the andesites are very compact, hard, almost jaspery in appearance, changing somewhat as they descend into the lower portions; and on the eastern edge those mountains are bordered by compact, red rhyolites that have flowed down into the valley to an elevation not much over 7,500 feet. Andesitic tuffs make up avery considerable portion of the country there, but, contrary to 344 GEOLOGICAL SURVEY OF THE TERRITORIES. their usual character, frequently show a compact texture. The andesite on station 23 has a very fine-grained, homogeneous paste of maroon color, with numerous crystals of oligoclase, few of orthoclase, and some of chlorite embedded in it. So great, however, is the variation that a short distance from the top the paste turns buff, the oligoclase has disappeared, sanidite occurring instead, and fine needles of hornblende replace the chlorite. Whereby these changes are produced that are only local, and sometimes limited to a very small portion of the rocks only, I cannot say, but strongly suspect that differences in the process of cooling, regarding both the method of, and time consumed in, cool- ing, may have produced these effects. All over the mountain, however, that rises considerably above timber-line, the rocks weather in thin Slabs, from one inch in thickness to several feet, giving a submetallic sound when struck with the hammer. Some of the mountains between Ouray’s Peak and station 23-have a slight color, from light red to yel- lowish, owing, probably, not to a changeof material but to a difference in the weathering. On station 24 the character of the andesite is very sim- _ ilar to that of station 23, showing the same compact texture, and the same -minerals, with the exception of orthoclase and chlorite, which latter is replaced by crystals of mica. Sanidite is contained in numerouscrystals. Magnetite occurs in considerable quantity. Asbefore, the same changes of color occur, due this time more to weathering, as the composition of the rocks undergoes no change. Taking the general aspect of the rock, it resembles trachyte to some extent; but its geological features and mineral constituents make it out as andesite. Leaving this interesting point and proceediug westward, we find the character of the country changing somewhat, the high, massive mountains disappear along Saguache Creek, and instead we find low table-hills, with steep sides and level tops. Frequently the sides of these tables have a stratified appearance, and the last upper stratum presents a steep, rugged face. A very characteristic feature of the mountains can be observed all along Saguache Creek, and also across the continental divide, that is, the terrace-formation on their sides. Evidently the tuff that forms these hills has at one time flowed alongin such a manner as to form a stratum ; another flow has succeeded it, perhaps after a lapse of considerable time ; and the conditions at present are such that the hill-side will not weather off so as to form an unbroken slope, but every one of these larger flows is designated by a sharpterrace of barren rock, which is well illustrated by the annexed cut. Frequently three, four, and even more terraces are found, one above the other, parallel to each other, presenting light colors mostly, varying from white to yellow, reddish, and light brown. Throughout the southwestern portion of the section, the occurrence of the trachorheites is uniform and very similar to those just de- - seribed. Station 32 is located on the edge of a trachytic ridge, where the rock is red, slightly vesicular, certainly enough so to give it the charac- teristic roughness, changing at times into black, then becoming more compact. Crystals of sanidite and brown mica are dispersed all through the rock, and hYalite is found coating the sides of any small fissures that may occur. MHyalite is found very frequently in these volcanic rocks, as is also jasper, the latter varying in color from white to yellow, red, brown, green, and black. ‘This trachyte contains but a trace of magnetite, while an andesite found near by contains a considerable quantity. Station 33 to the southwest of 32 is located upon a high, prominent point composed of andesite. The lithological character of this rock is so constant that, although a great many miles apart, no Specific differences are found, and in this instance again we have a rock i eeN eae es - ig. 11 pehng MR WE Leo Tie nie | Rasheadee |, \ = aes = i d Li ee iy EE )) Cor Oe GEE te oe e Sy bet Le i if ar (aoe a Ne rR Li Wc IAT es Ml a 4 i i ingle a Mi i TAL HAN r T Hail if W/; i ne el th || LAUT ETA Hi oe WS) ZZ oa hi nile | i i ie = rl me ll li ce Wi i Ci : vi df h, ‘ | | fy ff (i ye r ii | 1 i : ‘ee i! | Dike of Obsidian. SS ee —— = aoe GEOLOGY—SAN LUIS DISTRICT, SECTION C. o45 that could scarcely be distinguished from the andesite of station 56, more than eighty miles distant. Variations oceur within certain limits, and are repeated at almost every place of occurrence ina greater or less degree,*but the specific character remains true to itself. In the southern portion of section c andesite seems to form the highest peaks, well marked by their sharp, bold outlines, and their dark color, unusual in a countty of trachytes and tufts, while these latter compose the lower ridges and high plateaus. Station 34, west of Coochetopa Creek, is located on a sanidite trachyte ; a brownish ‘paste includes numerous crystals of sanidite, and also some of hornblende, black and bronze-colored mica. From that station north and eastward the tuffs, rhyolites, and trachy- tic ashes become more numerous again than they’ were in the more southerly portions, thereby chan oing somewhat the orographic features of the country, although it cannot be denied that this change may be partially produced by underlying sedimentary beds. The tuffs have overflown the Cretaceous beds east of the Coochetopa, and were proba- bly cooled under water, whereby their character is changed to a consid- erable extent, as they present all possible varieties and differences in composition and texture. Mostly, however, they are of light color vesic- ular, containing crystals of sanidite, mica, and, if rhyolitic, free quartz. At stations 26 and 27 we find a very interesting locality, showing a comparatively large variety of volcanic rocks, and at the same time the only deposit of sedimentary material that was observed in this great lava-region. Station 26 is located on a phonolitic andesite of a dark bluish-gray color, siightly vesicular at places, containing small needles of hornblende and small crystals of black mica and sanidite in a compact, microcrystalline paste. On the westside of the summit, the andesite shows columnar structure, each column being separated at a right angle to its longitudinal axis into numerous thin plates. Between stations 26 and 27 a low granitic hill makes its appearance, showing the andesitic cover for some distance. This granite is thoroughly altered by the effects of heat, which does not seem to have been quite sufficient, however, to bake it. Upon this granite, (a,) the Tertiary beds (d) are deposited, of which mention has been made above, covered on their western side by the rhyolitic ash lying upon the eastern slope of station 27. From white to yellowish pink and greenish, this ash presents itself as an agglomeration of feldspathic ingredients, mixed with small crystals of sanidite and mica, grains of quartz, fragments of andesite, and of obsidian also occur, altogether giving it the appearance of redeposited material. It is quite possible that it was deposited there at a time when Tertiary waters were still in that little basin, and that they owe a portion or all of the quartz-sand they contain to the fact of having taken it up from the lake-deposit. Not very far from the summit of the hill, the tuff becomes more compact, the fragments it contains are larger, its color a dark brown, forming a prominent bluff on that slope of the hill, About 25 feet; from the upper edge of that bluff, a horizontal dike or vein of ob- sidian (c) occurs, 15 feet thick, and extending across horizontally for nearly 100 feet, until it is lost under the fallen débris. At the point where our sketch i is taken, the obsidian shows spheroidal concretions, the largest one nearly 10 feet in diameter, the center of it forming a solid, round ball, with the obsidian nearest to it separating from the rest in concentrically spheroid scales. The obsidian contains small crystals of sanidite—therefore belongs to the porphyritic variety—and en- velopes numerous small fragments of the tuff. A curious factis that the tuff above the obsidian- dike is baked so thoroug ehly that it has become jaspery in texture, while that below remains unchanged. Quartz-is con- 346 GEOLOGICAL SURVEY OF THE TERRITORIES. tained in the shape of small fragments, which have been turned to semi- opal in the altered tuff. The cleavage of the latter has become con- choidal; it is hard, resembling jasper or massive porcelain more than any- thing else, and the change can be traced as far as the obsidian. As- cending to the summit of the hill, however, we again find andesite, identical with that of station 26. From the point where it covers the Tertiary beds the ash extends downward to Saguache Creek; and there follows along the base of the bluffs for a short distance. On station 26 the andesite shows a phenomenon that is rarely equaled, and by which i was led to term it phonolithice andesite in contradistine- tion to other rocks of that group. When striking the large bowlders, even those of many eubic feet in size, they give a clear ringing sound, closely resembling that from a bell. The Ringing Hills at Pottstown, Pa., are similar. In the southern portion of section ¢ several times caves were found in the tufts, a feature that seems to be characteristic to them. Crowning witha steeply-edged stratum some sloping hill, the caves had their entrance at the base of the rocky precipice, and extended inward sometimes for considerable distances. In several instances the shape of the entrance was so weil cut that the idea of its having been done by human hands suggested itself. Not unfrequently colummar structure was seen in different species of the trachorheites, as well in the andesite as in the tuffs, due most likely to particular circumstances by which the cooling may have been accompanied. Besides this immense area of voleanie rocks, we have two more in section ¢c, excepting those small remnants of overflows occurring in Tomichi Valley. Extending a little north, and about six miles west of station 45, is another accumulation of these rocks. It seems to be mainly trachyte, with probably some propylite, having a light-green paste, white to yellowish oligoclase, and a greenish hornblende. On the north side of the Gunnison another rock occurs that belongs to this group, covering the Carboniferous of station 38, composed of a light- grayish, almost white, microcrystalline paste, containing erystals of oligoclase and needles of hornblende, besides a very small quantity of magnetite. It is a trachyte, quite closely allied to propylite, and extends over but a small area to the southeast and east of the station. Station 42 is located on a trachyte of similar constitution, covering the Carbo- niferous rocks, which extends north and northeast into Dr. Peale’s _ district, where he has found it, and gives a more definite description of it. Dikes occur in considerable numbers throughout the granitic country, having a course of about north to south, and ¢ are composed of the same mineral constituents that characterize them in the other sections; 3 epi- dote and hornblende mostly replacing mica, while at other times mica predominates. Drift covers aconsiderable area along the western side of the Arkansas. A belt of about five miles in width runs along it, keeping parallel in its course and narrowing out toward the south. This drift is composed, so far as I have been able to learn from examinations at certain compara- tively isolated points, of material that was brought down by the river mainly; secondarily, by the different creeks striking the river from the west. Although glacial action seems to have had considerable effect in transporting drift-material higher up on the Arkansas, I have not recog- nized any such means of conveyance in that portion of our district. Taking into account the shifting of streams parallel to their own general course, if becomes evident that the material deposited immediately Bee GEOLOGY——-SAN LUIS DISTRICT, SECTION C. J47 along the base of the range parallel to the river must have been depos- ited by it, and not by any other means, provided lithological identifica- ion of the drift-rocks admits of no contradiction. This ‘latter does not seem to be the case, however, and the accumulation of the greater por- tion of the redeposited material I ascribe to the action of the Arkansas. A number of creeks running out from deeply-cut ravines in the mountains have cut in an almost str aight line through the drift; a cir- cumstance which is readily explained by the fact that its resistance was so small as to necessitate no considerable deviation from a straight line. As they have cut in deeply, however, forms strongly resembling moraines have not infrequently resulted, which might mislead. Oppo- site station 4, the canon of the Arkansas narrows and the drift-deposit disappears. Along Tomichi Creek a considerable quantity of drift has accumulated, covering about thirty to forty square miles, the material for which was brought from the neighboring granitic and quartzitic hills. Northwest of station 45 some drift has accumulated in the valley of the Upper Gunnison, part of which is due to the action of glaciers. In a long, narrow line, running from southeast to northwest, morainal de- posits sweep down from the ‘base of the high mountains to the valley. Characteristic narrow but level valleys, bordered on either side by lat- eral moraines, with a number of small glacial lakes, are found at the points of emanation. Changing their course slightly, these two moraines extend down into the valley, leaving at every favorable locality small lakes or swampy places, and they terminate on the sides in moraines, descending from 1,000 feet in height to 200. Reaching the valley, the ice melted and formed a large lake, at the place of which aswampy,low . country now is found, inhabited by hundreds of beavers. In these moraines gold-washing has been carried on formerly, and is still carried on in some of the neighboring gulches. This is the only instance through- out our entire district where I could really recognize the action of glaciers. Mineral deposits are found in only two localities of section ¢; the one on Mount Princeton, where a series of parallel veins are contained in the granite, running ‘between the strata, which are peculiarly well-defined there. They are about 12,000 feet above the sea, but several of them have been worked to a small extent. Usually the strike is from north- east to southwest, and the dip about 135° to the north, with slight varia- tions of either. The ores contained in these lodes are mainly galenite, sphalerite, and small quantities of fahlerz, resulting, when decomposed, in the formation of azurite and malachite. Argentite was found in a few specimens. According to report, assays that have been made are favorable. In the valley of the Upper Gunnison, 7. ¢., north and east of the entrance of the cafion, the drift contains gold, which has been worked at intervals for some years. In Union gulch, adjoining the yalley, there were several miners at work at the time of our visit, appar- ently well pleased with their results. Single nuggets of several dollars in value are frequently washed out. Probably the drift-material of that region may contain paying quantities of the precious metal, which some day will most likely be turned to account by the enterprising western miner. Résumé of section c.—In this section we have the greatest variety of granites met with thus far. Besides the red, middle to coarse-grained rock, that I think may safely be regarded as ‘the oldest, a repetition of the type found in the two proceeding sections, we have another one, composing the Sahwatch range, containing as its most prominent peak Mount Princeton: near that we have the protogine, possibly owing 348 GEOLOGICAL SURVEY OF THE TERRITORIES. its peculiar constitution to the close proximity with volcanic rocks; and lastly, the eruptive granite of station 38. Throughout, as well in lithologi- cal and mineralogical character as in the structure of mountains, the three main varieties can readily be distinguished. In other countries granites have been found, that are said to reach back only to very late geological ages; here we have one the protrusion of which I think falls into a Post-Carboniferous period. The evidence afforded by the Sangre de Christo range of section } is corroborated by the observations made here. Less noticeable than in the two preceding sections is a gradual or sudden rise of the main granitic mass, which, if it has oceurred, must have been but slight, and not of long duration or great power. An accumulation of hornblendic rocks is a curious and interesting feature, and the similarity they bear to alpine and other euphotides, combined with the fact of their usually reaching very high altitudes, may point to an analogy of formation and relation to surrounding rocks. Astonishing is the mass of volcanic material that had accumulated and found its points of outflow in this section, at the same time show- ing no very massive deposits at atfy one point, as might have been ex- pected. Upon the origin of this and the other volcanic effluvia, we will speak in the ‘“‘ Conclusion.” CONCLUSION. In concluding the report of the geognostic and geological features of the district assigned to me for 1873, it may be of value to give, in gen- eral outlines, the distribution of geological formations throughout it, and to speak briefly of the correlation existing between them. In taking a bird’s-eye view over the mountains of this district, it becomes strikingly evident at a glance that two main systems of mountain-ranges traverse the country: the one, geognostically granitic, in a direction a little west of north and east of south; the other, vol- canic, crossing it at almost right angles, having a course of about 15° south of west and north of east. Granite seems to be the oldest rock found there; but there are four distinet varieties of it, three of which are considerably younger than the first, the red to pink variety, mostly coarse-grained, abounding, with local accumulations of the one or other constituent mineral. The second type, the age of which will probably be correctly defined as Post-Devo- nian, is that which occurs in the northeast portion of section c, form- ing the high sharp peaks that are so characteristic to the range west of the North Arkansas. While oligoclase is of exceedingly rare occur- rence in the oldest granite, it is found to be the mineral second in quan- tity only to orthoclase in this instance, imparting an entirely different character both as regards appearance and weathering. Of probably the - same age we find the porphyritic protogine of station 45, owing its con- stitution most likely to some different circumstances experienced while cooling. Hruptive granite is the fourth variety, occurring in the Sangre de Christo range and on station 38, of Post-Carboniferous age, resem- bling in its lithological character more closely that of Mount Princeton. Although the term ‘eruptive granite ” is frequently used by Kuropean writers, this has not been done to any considerable extent by Ameri- cans; and I would state that I do not consider it eruptive in the same sense that basalt is eruptive, but merely wish to imply by that term See GEOLOGY—CONCLUSIONS. o49 that the granite, by some vertically-acting force the origin and effect of which cannot be discussed here, has been forced upward, may have not ~ only assisted in locally disturbing strata with which it was at one time in no immediate contact, but has actually, by virtue of this force, been brought into contact with such strata. Footing upon the observation of facts that to me cannot be otherwise explained, I see no discrepancy with any well-founded hypothesis that may be universally accepted to regard the immediate action of the granitic masses as implying the agent of a vertical force to which it must owe its elevation. Examina- tions were made with a view to determine the presence of magnetic iron in the specimens of granite collected in this district, and it was found that not one specimen was without it. Asa rule, the light-colored granites, of a more recent date than the red ones, contained more than the latter, a fact that can readily be explained by assuming that their younger existence upon the surface could not admit of so extended an influence of atmospheric agencies upon their constitution, while the older granite may probably owe its decrease in the percentage of magnetic iron, and, on the other hand, its red color, to the action of these agents. By increasing its percentage of oxygen, the iron compound contained would change in such a manner as to impart to the rock that color which it now possesses. It remains to be stated that there are two ex- ceptions to the rule above given, where in both instances magnetite was contained as a mineral impregnation in the red granite, in the one instance even in crystals of three-fourths of an inch in diameter. Of the Silurian formation we have some of the oldest strata, as indi- cated by the comparatively unsatisfactory paleontological remains, and from these upward the Devonian rocks also seem to be represented, although no strict identification was possible. The Carboniferous is well developed, showing great uniformity in the groups of strata. Con- sidering the imperfect evidence derived from the fossil remains below the Arkansas sandstone, there might be some doubt regarding its age, and the question could arise whether it would not be more correct to assign it a position parallel to the ‘‘ Old Red” of the Devonian; but, for reasons based upon stratigraphical evidence and the total absence of fossils that might decide, this has not been done. A wide gap now fol- lows, comparing the formations of this district with those analogous from other parts of the world, until the Mesozoic period is reached. The position of this series seems to be as well established as possible with the very meager amount of fossils that has been found. In some of his earlier expeditions, Dr. Hayden has found Pentacrinites in some strata that are recognized as having their position above the so-called “red beds,” which would settle the question, leaving ample space, how- ever, for any subdividing of the group. Well-defined and of admirable uniformity in character are the Cretaceous strata, to which the five adopted divisions apply without discrepancy. The gradual receding of the formations belonging to this group from the mountain-edge, the still greater development of this feature during the Post-Cretaceous epoch, speak for the gradual rise of the land west of them during a period of time that must be located in the close of the Cretaceous. Apparently a knotty question arises when the age of the “ Lignitic” beds is consid- ered; but undoubtedly future investigations, not merely of the paleon- tological remains, but of the geognostic relations they bear to over- and underlying formations, will tend to clear up any lingering doubts. Those found in our district seem (speaking with all the reserve that a mere su- perficial examination demands) to be of an age which can paleontologi- cally be referred neither to the Cretaceous nor to the Tertiary, analogous 350 GEOLOGICAL SURVEY OF THE TERRITORIES. perhaps in character to the Wealden formation of Europe, that is placed between the Jurassic and Cretaceous. Views of the present day regard- ing ‘‘formation” and ‘‘age” are merely conventional, and it is more than probable that by the time a little more of the remaining four-fifths of the land on the surface of the earth are explored geognostically and geologically, they will be compelled to undergo considerable modifica- tion. Vertiary, Diluvial, and Alluvial deposits are found under such condi- tions as would be favorable to their formation. In consequence of the rise of the main body of land, the marine Tertiary was forced to retreat farther toward those portions that were still submerged, and no strata were found that could be referred to this epoch unless of a local fresh-water character. Drift, belonging both to Diluvial and Alluvial ages, is abundant. Alluvial deposits, as everywhere, owe their charac- ter to the rock to which they owe their existence, and the old principle of ‘‘same cause, same effect” is clearly discernible. : Glacial phenomena, that seem to be more abundant farther north, were recognized in but one locality, and there they were not of any consid- erable extent. By far more varied, and of deep interest, are the volcanic eruptive rocks, so widely distributed throughout the district. Richthofen’s excellent classification, comprehensive and yet concise, finds a new support in the twenty- three hundred square miles of trachorheitic material contained in our district. Throughout, the given character of andesite, trachyte, and rhyolite could be relied upon as soon as the posi- tion of andesitic tuffs was properly recognized ; and although the dif- — - ferent conditions undoubtedly influencing the cooling of the masses at different points produced almost innumerable varieties, even within limited areas, his appreciation of identity and correlation was not im- paired. A question of great importance arises during the contempla- tion of the immense quantities of this material; it is the one touching their origin. Without entering upon the various hypotheses that have been advanced upon this point, with a semblance of more or less prob- ability, I will make a few suggestions that have occurred to meas the necessary consequence of the observation of facts. As stated above, it was impossible to find even a single one of the _ Specimens of granite free from magnetic iron, although more was found in the younger ones than in those preceding them inage. The same examinations carried on with a considerable number of trachorheites from different localities give the invariable result that andesite con- tains a large (comparatively speaking) percentage of this mineral; trachyte less; rhyolite still less ; the tuffs of these species giving results in accordance with those shown by the rock to which they belong. The rising percentage of silica as they are higher—younger in the scale— | until rhyolite contains free silica; their approximate uniformity in chemical composition throughout the world, which points to an origin from similarly constituted material; and their almost unexceptional occurrence in granitic countries, besides the great similarity ef percent- | age which their constituents show, upon analysis, with the constitu- ents of granite, seem to lead to the conclusion that they may owe their origin to a remelting of granite. More careful and specific examina- tions are required, however, to prove this hypothesis. With a view to so doing, I have undertaken investigations into the questions in- volved herein, and shall therefore do no more than suggest the idea until results obtained Justify a more complete and comprehensive as- sertion. Ao ee GEOLOGY—CONCLUSIONS. ool A few words may also be said regarding the distribution of the geo- logical formations over the entire district. Granite forms all the higher portions of the eastern edge of the Front range; but on the northern side of the Arkansas it is covered largely by trachorheites, and, to some extent, by sedimentary formations. Con- tinuing its course westward, it forms the main mass of mountains in the north, whereas the entire southwestern portion is volcanic. The sediment- ary beds of Silurian and Carboniferous age traverse the central portion of the districts in a narrow band in a southeasterly direction, the former edging the latter in the northern portion, disappearing in the south. Again, they reach into the northwest corner of the district coming from the north, and covering about one hundred and fifty square miles. Mesozoic and Tertiary beds are found only along the eastern edge of the Front range, with the exception of one or two isolated patches of small extent. The Cretaceous occurs all along that same edge, extending into the mountains in a few bays of ten to twelve miles in length, and is found in the western portion of the district, a continuation of the formation farther north. Voleanic rocks cover the granite partially in the eastern and northern half of the district, forming the high plateaus, while the granite appears in the eroded cations. A few isolated patches are scattered throughout the granites, one of them extending in a very narrow line parallel to the Sangre de Christo range. The largest portion is that forming the southwestern corner of the district, which probably extends consider- ably beyond it both west and south. Drift covers San Luis Valley, the upper valley of the Arkansas, and Wet Mountain Valley, besides small portions on the Tomichi, at Union Park, and on Taylor River Valley. The mineral resources of this district are confined to gold, silver, iron, coal, and marble, of which mention has been made in speaking of the several sections in which they occur. APPENDIX. MINERALOGICAL NOTES AND A CATALOGUE OF THE MIN- EBERALS OF COLORADO TERRITORY. MINERALOGICAL NOTES. One of the most interesting regions in Colorado, from a mineralogical point of view, is undoubtedly the vicinity of Gold Hill, of which Mr. Marvine treats in his report, as it is located within his district. There a number of dikes of porphyry have found their way out through the granite, and, contact between the two, a number of lodes have been found, several of which have attained considerable celebrity. The Red Cloud and Cold Spring are located on the two sides of a porphyry-dike 50 feet in thickness, striking about northeast to southwest, and from them principally the rare and valuable tellurids, sought for by mineral- ogists, have chiefly been obtained. Prof. F. L. Schirmer, of Denver, | had the kindness to supply me with a number of specimens from the Red Cloud mine, which I have examined, and herewith give a report upon. Before speaking more particularly of the tellurids, a few words may be said explanatory of the circumstances under which they are asso- ciated with other minerals at the mines of that locality. Composing the dike between the Red Cloud and Cold Spring, we find a porphyry of dark-grayish to purplish color, containing numerous small crystals of two varieties of feldspar in its cryptocrystalline, compact paste. While forming the hanging-wall of the Red Cloud, it is the foot- wall of the vein opposite. Fragments of this porphyry, mixed with par- ticles and streaks of quartz and feldspar, together with small flakes of tale, make up the gangue-rock of the Red Cloud, collecting in small cavities, crystallizing in cubes combined with the pentagonal dodeca- hedron. Pyrite occurs throughout the vein, also forming at times nar- row streaks, but invariably with a strong tendency to crystallize. At some points the porphyry too is thoroughly impregnated with this min- eral. Gaienite occurs sparingly in cubical crystals; also sphalerite in narrow seams. Quartz-crystals, coated by ferric oxide, are found in the small cavities occurring with them, both of more recent origin than the sulphurets. Compounds of silver, copper, selenium, &c., with sulphur, seem to be wanting entirely ; instead, however, we have the unusually rich occurrence of tellurets, of which we shall speak presently. To the west of the Red Cloud is the Cold Spring, the ores of which show no variation, however, while the same granite and the same por- phyry form its walls. Hast of the Red Cloud, striking almost due east and west, is the Wi- nona, located between two walls of gneiss. In this lode the gangue- rock is mainly quartzitic, containing small portions of decomposing feldspar and of talc.- Chaleopyrite and pyrite form the main ore, occur- ring in streaks and thin threads partly, partly disseminated in erystals of cubical and dodecahedral form throughout the gangue. | GEOLOGY—MINERALOGICAL NOTES. 353 Some distance to the southwest of the Red Cloud we find the Central, Seven-Thirty, and Americus, located contact to a long dike of porphyry and the surrounding granite. In a light-gray microcrystalline paste we find embedded numerous small crystals of black mica, crystals of a prob- ably triclinic feldspar, and small, irregular particles of white quartz. Of all the veins located on this dike, the main one is chalcopyrite and pyrite, with the usual accessories; sphalerite and galenite occurring rarely. In none of the specimens that reached me could [ find any tel- lurets, although their analogous mode of occurrence might lead to some expectation of their presence. In various parts of the world, compounds of tellurium with other metals have been found, so that the first attempt at recognizing analo- gous minerals from the Gold Hill region was to identify them with those already described. It seems to me that the tellurets of the region under consideration show a greater variety of composition than those of other localities. For entering into combination with other elements, the facil- ities must have been great; we have one compound, that of tellurium and iron, which, although not occurring pure, enters into the formula of the mineral. During the coming field-season, I expect to obtain a satisfactory supply of material, in order to give a complete synopsis of the mineral-oceurrences of the Gold Hill locality. Two minerals were found, occurring both at the Red Cloud and Cold Spring lodes, that could not strictly be parallelized with any known species, and I have reserved the right of distinguishing them by a sepa- rate name, if subsequent examinations of more abundant and purer material will warrant it. No. 1. Isometric, imperfect crystals observed. Cleavage cubical, good. Mostly found in thin threads, or in small, irregular, foliated masses. Hardness, 2 to2.5. Specific gravity, 8.5253. Luster metallic, splendent. Color bright silver-gray to steel-gray ; pale bright-yellow when exposed to atmospheric influences a short time. Streak metallic, gray to silvery. Opaque; brittle; partly malleable and sectile. On account of the small quantities that could be spared for analysis, the teliurium was not determined but calculated; the result of careful qualitative examinations having revealed no trace of any other elements than those found and given below. By analysis the following constituents were obtained: Pp, “Be, Ag, Au, Te by diff; 53.19 5.05 0.31 trace 41.45 =—=100.00 Calculating the simple tellurets for each one of these constituents, we find there are required for— 53.19 Pb, 5.05 Fe, 0.31 Ag, 32.90 11.55 0.19 — 44.64 tellurium. It is probable that slight replacements may account for the smaller quantity of tellurium found. The percentage of constituents found leads to the formula— 3 Pb Te+ Fe Te a very minute portion of lead having been replaced by silver. During the examination, great pains were taken to procure the mineral as pure as 23 GS ‘ 354 GEOLOGICAL SURVEY OF THE TERRITORIES. ee and only such fragments that showed a distinct cleavage on all sides were subjected to the tests. Pyrite almost invariably is found associated with this mineral, and the idea suggested itself that the iron might be accounted for in that way. Several trials were made, therefore, without giving any sulphur however. It may be stated here that all the examinations were made of pieces obtained from one specimen. This mineral has in its physical characters some resemblance to the Altaite, which, however, contains no iron and about 60 per cent. of lead. In the open "tube, the assay gives off white fumes of tellurous acid, condensing into colorless drops upon being heated to a high degree. Before the blow-pipe on charcoal, with the oxygen-flame, the coal is coated with a white layer some distance from the assay, highly volatile, and near it a grayish-silvery coating is formed, consisting of the vol- atilized and recondensed mineral. After treating the assay on charcoal ‘a little while, it becomes slightly magnetic, melts readily, and volatilizes at a comparatively low temperature. When gently warmed with concentrated sulphuric acid, not heated to boiling, the tellurium contained in this mineral imparts to the acid a cherry-red color, more or less intense. Nitric acid affects it; nitro-muri- atic dissolves it. The solution obtained is yellow, owing its color to the presence of iron. This species occurs both at the Red Cloud and Cold Spring mines. If subsequent investigations, with a more ample supply of good material, confirm the result of the above examinations, I shall propose to dis. tinguish this mineral from other tellurets of lead by the name of Henryite, dedicated to Prof. Joseph Henry, director of the Smithsonian Institution. No. 2 Probably orthorhombic, (no crystals were found from which the crystalline form could be deduced beyond a doubt;) occurring mostly in thin threads and foliated masses. Cleavage perfect; hardness, 1 to 1.5; luster metallic, splendent; streak submetallic, dark-gray to black ; color between bright lead-gray and steel-blue; opaque; partly malleable and sectile; flexible when broken into thin scales. In consequence of being obliged to work with very small quantities, it was impossible to make more than a partial quantitative examination, which, however, combined with the qualitative, appears to distinguish this mineral from any known species: Au, Ag, 18.82 28.60 per cent. while the qualitative analysis revealed yet tellurium, iron, and lead; of the latter merely a trace, however. An approximate determination of the iron leads me to infer that the formula will be— 3 Ag Te + (Au Fe) Te In this mineral, the percental ratio of Au to Ag is 2:3, while in the mineral nearest related to it, in the Petzite,it is 5:8; and while Petzite contains on an average 25 per cent. of gold and 40 of silver, these figures are not so high in our mineral. In the open tube it gives off tellurous acid, acting like No.1. Before the blow-pipein the oxygen-flame, it coats the char coal white, giving in the reduction flame an impure globule of gold and silver. After being heated ¢ 7 sae GEOLOGY—MINERALOGICAL NOTES. 355 a short time, the assay becomes highly magnetic, indicating the presence of a Fe Seas quantity of iron. Nitro-muriatic acid decomposes the minera Subject to the same conditions as No.1, I shall, if the results are subsequently verified, propose for this mineral the name of Schirmerite, dedicated to Prof. J. F. L. Schirmer, of Denver, who tame supplied me with specimens from his rich store. NATIVE TELLURIUM. Hexagonal; occurring massive and in small crystals; lateral cleavage, perfect ; form, columnar masses in the accompanying white quartz. Hardness, 2 to 2.5; specific gravity, 5.802, which is lower than that given for tellurium, 6. 1 to 6.3; but may be ‘explained by the fact that the metal and quartz could be separated but imperfectly. Structure, *° lamellar; color, tin-white to light steel-gray ; luster, splendent; streak, submetallic, light-gray to gray. In the open tube it gives off whitefumes of tellurous acid and a strong selenium odor. Before the blow-pipe, on charcoal, melts readily, coat- ing the latter white in the oxygen-flame; black or very dark-gray in the red flame. Treating for some time with the red flame on charcoal and moistening the black coating with concentrated sulphuric acid, the coating will turn a bright carmine upon warming gently. Held intoa . steady oxygen-flame it colors it blue, with the edges tinged bright green. Bismuth produces a slight yellowish tinge on charcoal near the assay. In the closed tube the characteristic red deposit occasioned by selenium is found. As stated above, this tellurium is intimately associated with quartz, which composes 52 per cent. of the entire mass. An analysis, in which the constituents other than tellurium were determined approximately, gave the following result: Te, Se, Fe, Bi, Au, Ag. 90.85, approximate, trace, trace. Having obtained more material, a full analysis will be given. Itis not so pure as the tellurium from Transylvania, which yielded from 92 to 97 per cent. of the metal. CATALOGUE OF THE MINERALS OF COLORADO TERRITORY. The following is a list of the minerals found in the Territory of Col- orado, given as completely as possible up to date. In compiling it, the observations of Professor Schirmer, from Denver, Mr. J. A. Smith, ter- ritorial geologist, Mr.:-von Schulz, EH. M., Mr. Peters, E. M., Mr. Frazer, HE. M., Dr. A. C. Peale, Mr. Marvin, and myself have been used. The single initial after the enumeration of each locality or series of localities gives the name of one of the above-mentioned gentlemen by whom the mineral was collected or observed at that locality. Mr. Smith’s Cata- logue of the Principal Minerals of Colorado afforded much valuable in- formation. The comparatively meager representation of mineral species in a country so richly endowed with mining-lands as Colorado is is per- - ceptible at a glance. Very little definite and applicable knowledge has thus far been gained relative to the distribution of minerals and ores throughout the world, and every catalogue, however small, if only ac- curate, adds its share ‘to the further development of that knowled ge. 356 GEOLOGICAL SURVEY OF THE TERRITORIES. ACTINOLITE.—In radiated form, of light-green color, on station 2, BH. On Buffalo and Sopris Peaks, P. Bergen’s ranch and North Boulder Creek, S. AGATE.—Cloudy, of white and gray color in the trachytie formations of station 27, in various forms at the Los Pinos agency, H. In South Park, in the Arkansas Valley, and on the Frying Pan in varieties, P. Throughout Middle Park, M. ALABANDITE.—At Quartzville, Peters. ALABASTER.—Mount Vernon, S. ALLOPHANITE.—Franklive mine, in Gilson Gulch; Fowler and Wells’s tunnel, Sugar Loaf district, 8. ALUMINITE.—Mount Vernon, S. ALUM.—Mount Vernon, 8. AMAZON STONE, (Adularia.)—Elk Creek, S. *AMETHYST.—At Nevada and other neighboring localities, S. On Rock Creek, P. AMIANTHITE.—North Boulder Cr eek, H. AMPHIBOLE.—Bufialo Peak, P. Montgomery, Peters. ANGLESITE.—Freeland mine on Trail Creek, S. In crystals at the Horse- shoe lead-mine, in South Park, Peters. ANHYDRITE.—On Elk Creek, F. Crystallized at the salt-works in South Park, Peters. ANTHOPHYLLITE.—North Boulder Creek, S. APATITE.—At Fairplay, Bebers. APOPHYLLITE.—Station 2 2, HE. ARAGONITE. —Occurring in the form usually termed flos ferri, very beautifully in Marshal’s tunnel, Georgetown, EH. Golden, 8. ARGENTITE.—Colorado Central Mine, Terrible, and other mines at Georgetown; in the No Name, Caribou, and others at Caribou; in some mines near Nevada; in the Senator lode of the Hardscrabble mining-district; it occurs mostly in small quantities, imbedded either in quartz or in the predominating ore; when decomposed, native sil- ver is the result, EK. At the Silver Star, Moore, and other mines near Fairplay, Peters. ARSENOPHYRITE.—Priest Mine, Fairplay, Peters. ASBESTUS.—Oceurs in small quantities, partly radiated, near Caribou, EH. AVENTURINE FELDSPAR.—On Elk Creek, S. AZURITE.—In the No Name, together with malachite, the result of de- composition of fahlerz, Caribou; in the Rosita mines in Hardscrabble, E. On Trail Creek, S. On Crater Mountain, in the mines around Fairplay, and in the mines of Elk Mountain district, P. BIsMUTHITE.—In the Las Animas mine, pseudo-morphous after— BIsMUTITE.—F rom the Las Animas mine, Sch. Barite.—In yellow tabular crystals, clear in the Tenth Legion mine of Empire, in the Terrible mine near station 17, and on station 46; near Canyon City transparent crystals occur in the arenaceous formations of that locality, E. In Gilson Gulch, Georgetown, S. Crystals occur in the limestones around Fairplay, P. BASANITE.—Hast of the salt-works in South Park, P. BERYL.—On Bear Creek, Tiffanny’s ranch, S. Biorire.—On Butfalo Peak and station 64, Be: BITUMINOUS COAL.—At several localities ‘along the Border range, at Pueblo and Canyon, EH. On Trout Creek Pass, Ver Brucrre.—On James Creek, F. OALCILTE.—In small crystals, scalenohedra, at the Monte Christo Cen- tral; on station 35, camp 32, H. At Mount Vernon, Bergen’s ranch, eepricit | GEOLOGY— MINERALOGICAL CATALOGUE. 357 S. Rhombohedral crystals on Cheyenne Mountain; in the limestones of South Park; scalenohedra in Elk Mountain district; fibrous in Trout Creek Park ; on Frying-Pan Creek, P. CALEDONITE.—Freeland mine, Trail Creek, ’S. CAOLINITE.—Camp 42, E. CARNALLITE.—Salt-works, South Park, Peters. CARNELIAN.—Middle and South Parks, M. Los Pinos agency, E. CERARGYRITE.—Gilpin County lode, Black Hawk, 8. Small, compact quantities in the Wade Hampton mine, Peters. CERRUSSITE.—J. P. Whitney mine, in very small crystals; Central ; No Name, Caribou ; Caribou mine; Silver Hills mines and Rosita minesin the Hardscrabble district, BE. Freeland mine, Trail Creek, S. In the Horseshoe mine it occurs earthy, and is found throughout the mines of Elk Mountain district, P. CHALCEDONY.—On station 27; at the Los Pinos agency, E. Middle and South Parks, M. and P. ’ Buffalo Park; Fair Play; Frying Pan; Trout Creek, &c., P. CHALCANTHITE.—On Clear Creek below Black Hawk, in a deposit, and on several dumps near Central, E. CHALCOCITE.—Bergen district, pear Idaho City, F. piveL oy lode, Bear Creek, 8. CHALCOPYEITE. —Auriferous in the Bobtail, Winnebago, Dalle! Gun- nell, Running, Kansas, California, and, other mines at and near Cen- tral; mostly occurring compact, and frequently very intimately inter- mixed with pyrite. It occurs in every paying gold-mine in Gilpin County, and the miners seem to think a great part of the ‘‘ pay” de- pendent upon its presence. It also occurs in the Terrible, Pelican, Cold Stream, and other mines of Georgetown, as well as in those of Caribou and Hardscrabble, H. In the gold and silver mines of Fair Play and the Elk Mountain District, P. CHLORITE.—On station 45, E. On Trail Creek, S. On Sopris Peak, P. CHLOROPHANITE. —Bergen district, S. CuROMITE.—Massive ; Silver Hills and Fair Play, Peters. CHRYSOCOLLA.—Champion lode, Trail Creek, S. CHRYSOPRASE.—Rare, in Middle Park, 8. CoAuL.— Vide BITUMINOUS COAL. CopPerR.—Native; arborescent in the Gregory lode, Central, E. CopPERASITE.—On the dumps of the Wood Lode and Nevada, E. CUPRITE.—In crystals, from Sacramento Gulch and from the Sweet Home mine, Peters. DoLoMITE.—F rom the Four-Mile Creek, P. EMBOLITE.—Peru district, Snake River, By. EPIDOTE.—In crystals together with garnet on Gunnell Hill, Central; in crystals, small, on stations 17, 43, 46,50, and 77. A large number of the hornblende-dikes traversing the country contain epidote, either massive or in small crystals, E. On the sammit of Mount Bros, Lake Creek Cafion, Grand Mountain, Elk Mountain Ridge, and all through the foot-hills, P. On Trail Creek, S. FAHLERZ. —Terrible, Colorado Central, Pelican, and other mines of Georgetown; No name, Caribou, and others at Caribou ; station 46, E. For particulars see chapter 1. FELDSPAR.—Occurs in the gangue-rock of a large number of mines near Central and Georgetown ; crystals showing the Carlsbad twin-system are found in Gregory Hill, Central, in the porphyry, at station 46, at Rosita, E. Twins are also found in the porphyries of Gold Hill, M., on Elk Creek; and at Idaho, S. Compare ORTHOCLASE. 358 GEOLOGICAL SURVEY OF THE TERRITORIES. FIRE-CLAY.—Golden, Ralston, Boulder, &c., S. FLOAT-STONE.—Mammoth lode, Central, 8. FLOS FERRI.— Vide ARAGONITE. FLUORITE.—Terrible mine, Georgetown, in light-green cubes; in small erystals and massive, of violet color, on Mount McClellan and Gray’s Peak, E. . On Bear Creek, S.; massive, pink and violet in the Sweet Home mine, Peters. GALENITE.—In narrow seams, fine-grained, Winnebago ; feathery in the Dallas mine; coarse-grained in the J. P. Whitney, Running, Monte Christo, Forks, and other mines of Gilpin County. In the Colorado Central, Equator, Star, Pelican, Terrible, and others it occurs in large quantities. The Cold Stream shows beautiful crystals, combination of cube and octahedron, with rarely the rhombic dodecahedron. The International, at an elevation of about 12,300 feet, has a heavy vein of galenite. The No Name, Caribou, Fourth of July, and other mines in Boulder County contain the mineral. The Silver Hill mines (fine- grained) and the Rosita mines in Hardscrabble district. On station 46, EK. Hamilton, the mines around Fairplay show crystals; the mines of Hik Mountain district, the head of lowa and of Empire Gulch contain galenite. In small scattering quantities it is found almost throughout the country, P. : GARNETS.—Crystallized in rhombic dodecahedra and sometimes ikosi- tetrahedra; found together with epidote in the dike on Gunnell Hill. Closely resemble the garnets from Auerbach, in Germany. In mica- schist at camp 14 and at station 22, E. On Trail Creek, Bergen, &c., S. Montgomery, Peters. GoLD.—Native gold in very small and indistinct crystals in the Bob- tail, Gunnell, Quartz Hill, near Central, E. Tarryall Creek, Placer Diggings, near Fairplay, in imperfect crystals and lamine ; in Wash- ington and California Gulches, in the Placers of Union Park, and numerous other localities, P. Occurring as the result of decomposi- tion of the tellurids at Gold Hills, M. Lately discovered native in large quantities, though very minutely distributed, in the quartz- ledges of the San Juan mining-district. GOSLARITE.—On the ‘dumps of the Wood lode, Leavenworth Gulch, near Central, HE. : GRAPHITE.—Trinidad mine, Las Animas County, Sch. GREENOCKITE.—On sphalerite of the Dallas mine, Black Hawk, E. GypsumM.—Is distributed very widely throughout the Cretaceous forma- tion of Colorado. Good crystals arerare. Selenite is the usual form of its oceurrence, frequently being found in twins. Hauitn.—Salt-works of South Park, along some parts of the Platte River in springs, P. Found as salt-licks in various parts of the Ter- Titory. i HEMATITE.—Specular, on Procer Hill, Central, E. Headof Bear Creek ; fibrous and specular in Philipps mine, Silver Hills ; in the mines of Eik Mountain district ; micaceous on station 65; on Sopris Peak, P. HENRYITE, n. sp.—Red Cloud mine, Gold Hill, Sch.and M. Cold Spring mine, M. HITCHCOCKITE.—On copper minerals of the Dallas mine, Black Hawk, E HoORNBLENDE.—Occurs in numerous localities in the dikes, so that it would be useless to enumerate them. Good crystals none were found. Radiated on station 43, E. HYALITE.—On stations 33 and 34 in trachyte, E. At the Hot Sulphur Springs of Middle Park, 8. ; ENDLICH} GEOLOGY—-MINERALOGICAL CATALOGUE. 359 IDOCRASE.— Vide VESUVIANITE. Tron.—Native, in the Colorado meteorite found in 1866, S. J AMESONITE.—Sweet Home mine, Peters. San Juan, Sch. JASPER.—Green and red, station 33; yellow, red, brown, gray, Los Pinos Agency, EH. Throughout Middle and South Parks, M. and P. LABRADORITE.—Near Golden in the dolerites, E. Near Fairplay in the trap-rock, P. LEAD.—Native, in Hall Gulch, Summit County,Sch. At Breckenridge, S. An announcement of native lead must always be received with the necessary caution. The specimen owned by Professor Schirmer I have seen, but, although it had a very “ natural” appearance, was unable to decide. LEPIDOLITE.—Station 17, in a form resembling the Saxon zimuraldite, B. Levucite.—Table Mountain, Golden City, 8. LEUCOPYRITE.—Spanish Bar, 8S. Licori1re.—North Clear Creek, 5. Liwonite.—Near station 17, H.; in the Tertiary sandstones west of Plum Creek, near Colorado City, P.; in several localities of South Park, Peters. MAGNESITE.—In small quantities in the running lode at Black Hawk, E. MAGNETITE.—In loose nodules on Gunnell and Procer Hills, at Central ; in small octahedrie crystals in the gneissic rock on station 1; on sta- tion 54, EH. Occurring in the granites of various localities, Silver Hills, White House, Capitol, in the doleritic rocks generally, P. At Idaho and Caribou, 8. MALAcHITE.—Is found as the result of decomposition of fahlerz and other minerals at the Dallas, Leavenworth, and other mines near Cen- tral; at the No Name, Caribou, Seven-Thirty, Fourth of July, and others, at Caribou; at some of the Georgetown mines; at the Hard- scrabble mines, on station 46, and other localities, E.; at Crater Mountain, in the mines of Fairplay and Elk Mountain district, P. MARCASITE.—Philipps mine, Fairplay, Peters. MELACONITE.—Occurring at the Gunnell, Briggs, Leavitt, Leavenworth, and other mines, near Central, E.; at the Unknown mine in Mont- gomery, Peters. MELANTERITE.—On the dumps of the Wood, Dallas, and Kansas mines, and others, near Central, K.; in the Sweet Home mine, Peters. MESITINITE.—Black Prince lode, Lump Gulch, S. METEORIC IRoN.— Vide IRON. Min1uM.—Freeland mine, Trail Creek, S. MISPICKEL.—Together with pyrite in the Bobtail and other mines, E. MOLYBDENITE.—Leavitt mine, at Central, S.; occurring in thread-like veins in Silver Hills, near Fairplay, Peters. Muscovitze.—In good crystals on station 2, and in the coarse-grained granite near Cafon City; throughout the granite, and partly in the schist-rocks, E. OxsIDIAN.—Porpbyritic, in a dike, at station 27, E.; Buffalo Peak, Arkansas Valley, and Union Park, P. Onyx.—Middle Park, M. OPpAL.—Milky and precious at Idaho City, E. ORTHOCLASE.—In crystals in the porphyries on Gregory Hill, partly altered into sanidite. It occurs sometimes in very large pieces throughout the coarse-grained granites of Colorado, E.; in the por- phyry-dike at Gold Hills, crystals of large size, M. ' PEGMATITE.—At several localities in the vicinity of Georgetown,.on station 2, E. Bear Creek and Gold Hills, in Boulder County, S. J 360 GEOLOGICAL SURVEY OF THE TERRITORIES. PETROLEUM.—From the oil-wells in Oil Creek Cation, to the east of Canyon City, H. PrEerziTE.—In the gold-mines of Gold Hill, occurring in narrow seams and veins, M. PHLOGOPITE.—On station 46, E. PITCHBLENDE.—Occurs in large quantities; massive in the Wood lode in Leavenworth Gulch, near Central, E. POLYBASITE.—In tabular crystals at the Terrible mine, near George- town, H. PRASE. Middle Park, M. PREHNITE— Fair Play, in some of the mines, Peters. PROUSTITE.—Occurring in the Brown lode, intermixed with galenite, F. PSEUDOMALACHITE.—Little Platt River, south of Fair Play, P. PsILOMELANE.—Seaton mine, Idaho, occurs in small quantities, H. PYRARGYRITE.—In the Colorado Central, Terrible, International, Cold Stream mines, at Georgetown, associated with galenite, fahlerz, and sphalerite, E. In the Brown lede with galenite, F. PyRITE.—One of the most widely-distributed minerals in the Territory. As a rule, it is auriferous, occurring crystallized in pentagonal dodeca- hedra in the. Bobtail, Bates, Briggs mine; in cubes combined with the pentagonal dodecahedron at the Winnebago, Mack, Dallas, Kan- sas, Grand Army, Gunnell, and other mines, all near ’ Central City. In immense bodies it is found in the Mammoth, Briggs, and Leavitt lodes. It is found crystallized in the Terrible, Pelican, New Boston, Coid Stream, and other mines near Georgetown ; at the Tenth Legion mine in Empire; in cubes at stations 45 and 46, E. Found also in Silver Hills, crystallized i in the mines of Buckskin. Cubes of four to five inches edge in the Philipps mine; in the Elk Mountain district, on Kagle River; 3 in octahedra on station 65, P. In the mines near Idaho, crystallized and massive, M. PYROLUSITE.—Massive at Buckskin and in Silver Hills, Peters. PYROMORPHITE.— Freeland lode, Trail Creek, S. PYROXENE.—Near Fair Play, Peiers. QUARTZ, CRYSTALS.—Gunnell lode, Briggs mine, Quartz Hill and other localities near Central. In the Rosita. mines, in some of the George- | town mines, at station 46, E. On East River, in the mines of Hlk Mountain district, lowa Gulch, Sopris Peak, P. : QUARTZ, SMOKY. voy the Colorado divide ; large crystals on the Upper Platte, and on Pike’s Peak, P. QUARTZ, ROSY.—On station 70, E.; camp 39, P.; Bear Creek, S. RHODOCHROSITE.—S weet Home mine, Park County, Sch., in very beauti- ful specimens, and in the Diadem mine, Buckskin, P eters. RuTiLeE.—On Ute Pass, occurring in quartz, Peters. SARDONYX.—In Middle Park, M. SCHIRMERITE, JN. sp.—Red Cloud and Cold Spring mine; Gold Hill, Sch. and M. SCHREIBERSITE.—In the Colorado meteorite, S. SELENITE.—At various localities in the shales, station 35, E. SEMIOPAL.—At Los Pinos agency, E. SIDERITE.—Crystallized in South Park, Peters. SILVER.—Native, as wire-silver at the Terrible, Georgetown, at the In- ternational on Mount McClennan; as wire-silver in the No Name and Caribou mines at Caribou, EH. In small nuggets and thin scales near Fairplay, in Washington Gulch, Homestake lode, P. SINTER.—Siliceous, South Park, S. ein GEOLOGY—MINERALOGICAL CATALOGUE. 361 SMITHSONITH.—Jones’s mine on sphalerite, near Central, K. Running lode, Black Hawk, F. Sopa.—Carbonate, from the Hot Springs of Idaho, E. SPHALERITE.—Occurs in almost every mine; only few exceptions take. place. In the lead-silver’ mines it is more abundant than in the gold, mines. It is found in the Winnebago, dark brown, Dallas, Gunnell, J. P. Whitney, Kansas, Wood, California, Running, Bobtail, Briggs,, (small quantities in these two. ») Monte Christo, and numerous other: mines in the vicinity of Central. The mines of Georgetown invaria-\ bly contain it. The Caribou mines show at times large quantities of the mineral. Station 46, EH. Sphalerite containing cadmium is found in several mines near Fairplay, Peters. SPINEL.—Crystal mine, Virginia Caiion, S. STEPHANITE.—Colorado Central, Georgetown, E. Moose mine near Fairplay, and others, Peters. STrBNiTe.—Terrible mine near Georgetown, E. SULPHUR.—In a small crystal on galenite from the Clifton mine near Central, von Schulz; found in Middle Park, S. SYLVANITE—In the Red Cloud mine of Gold Hill, occurring in foliated masses and thread-like veins, M. TALC.—In fine scales among the gangue-rock of the Bobtail and Kan- sas near Central. In light-pink scales in the Silver Hills and Barton mines, Hardscrabble district, E. On Sopris Peak, P. TELLURIUM, NATIVE.—At the Red Cloud mine of Gold Hill, in erystal- line masses, belonging to the hexagonal system. Found in @ Speci- men obtained from Professor Schirmer. TENNANTITE.—Crystals in Buckskin Gulch, Peters. Geneva district, Park County, Sch. THTRAHEDRITE. —Crystals in Buckskin Gaibh, Peters. TOURMALINE.—In the quartz of Gunnell Hill, Central, of Running Hill, Black Hawk, E. On Guy Hill and at Nevada, 8S. Station 64, P. Crystals with both terminations at Montgomery, Peters. TuFFA.—Calcareous, Currant Creek, E. Roaring Fork and Frying Pan, P. TURQUOISE.—Southern Colorado, doubtful, Ss. URANINITE.—On thedumps of the Wood lode in Leavenworth Gulch, E. VESUVIANITE.—In large crystals of simple combination on Mount Italia, station 64, P. WILLEMITE.—Jones’s mine, Central, E. WOLLASTONITE.—Near Fairplay in the limestones, Peters. ZINCITE.—Jones’s mine, Central, 8. ZINKENITE.—Sweet Home mine, small crystals, Peters. ZIRCON.—Bear River, Middle Park, S. as oui Nat - ae De tars. Bitar (all ) PAG Ea: SPECIAL REPORTS ON . PALEONTOLOGY. icine of sy, a 7 Neiesp yet wen nae ee meres se : ; re ih THE LIGNITIC FORMATION AND ITS FOSSIL FLORA. BY LEO LESQUEREUX. COLUMBUS, OHIO, July 14, 1874. DEAR Sir: I send you herewith my report on the botanical paleon- tology of the Tertiary formations of the Rocky Mountains. The results of the explorations of 1875 in regard to my special researches are exposed in the description of the new species of fossil plants, and in the discussion of the data furnished by these plants on the age of the Lignitic formations. As there has been of late some discussion on this last subject, and as the opinions of the explorers do not yet agree, I have reviewed in the first part of my report the facts and arguments bearing evidence on the age of the Lignitic; in the second part, I have marked, by tables, &e., the distribution of the Tertiary flora in relation to the periods which they seem to represent; in the third part, the description of the new species, or of those which were not yet known from American specimens, is given; and the fourth has a review on the climate during the North American Tertiary epoch, as indicated by the character of the groups of its fossil flora. Besides what is due to the co-operation of the members of your corps. in the collection of specimens of fossil plants, the survey is greatly indebted to Captain Berthoud, and to Mr. A. Lakes, of Golden, for the discovery of new species and the communication of splendid specimens. Very respectfully, yours, L. LESQUEREUX. Dr. F. V. HAYDEN, United States Geologist, Washington. INE RO Du Cc LLON: I shall begin my report of this year by a more detailed review of the essential facts and data which, furnished essentially by vegetable paleontology, have forced my conclusions on the age and the geological distribution of the Lignitic formations of the West. There is always some uncertainty in the reference of fossil species to peculiar geological stations, when the paleontologist is called to describe them and judge of their geological relations without having himself examined the localities wherefrom the materials have been derived; this on account of a casual mixing up of specimens, and also because the more characieristic’species, which are sometimes of rare occurrence, escape the eye of those who, unacqnainted with fossils, collect speci- mens at random, and wherever they find them, for the examination of a specialist. For this reason I have to base my classification on the localities which I have visited myself, and on those which, either from stratigraphical evidence or by a close analogy in the characters of their fossil remains, are ascertained as synchronous. a ist. I refer to Hocene (Lower American Hocene,) all the coal-strata of the Raton Mountains; those of the Cation City coal-basin; those of Colorado Springs, where acoal-bed, the Gehrung’s, is opened and worked; those of the whole basin of Central and North Colorado, extending from Platte River or from the Pinery divide to south of Cheyenne, in- cluding Golden, Marshall, Bowlder Valley, Sand Creek, &c., and, in Wyoming, the Black Butte, the Hallville, and the Rock Spring coal. By analogy of geological characters, compounds, and succession of strata, as indicated by Hayden, Leconte, and others, and also by the presence of species of fossil plants, which I consider as leading plants of the group, I refer to the same Eocene formation the Lignitic beds of New Mexico as far south, at least, as the Placiére anthracite coal; in Wyoming, those ‘of Bear River; and in Utah, those of Coalville, as described by Professor Meek in the former report of Dr. Hayden, (1872, p. 435.) From its fossil plants, the coal of Nanaimo, Vancouver Island, is referable to this Section. 2d. I consider as American Upper Eocene (or Lower Miocene, the coal- strata of Evanston, and from identity of the characters of the flora, as seen from the specimens communicated to me, those of six miles above Spring Cafion, near Fort Ellis; of the locality marked near Yellowstone Lake, among basaltic rock; of Troublesome Creek, Mount Brosse, and Elk Creek, Colorado. - The specimens from Bellingham Bay, Washington Territory, refer this locality to the samé horizon. 3d. To the Middie Miocene I refer the coal-basin of Carbon, and from the identity of vegetable remains the Washakie group, Medicine Bow, Point of Rocks, and Rock Creek. 4th. To the Upper Miocene belongs the Green River .group of Wyo- ming; the coal of Elko Station, Nevada; the leaf-bearing strata of South Park, near Florisant and Castello Ranch; of Middle Park, and of Barrell’s Spring. The localities where only a few specimens of undeterminate relation have been obtained, and which are not named in this connection, are of little’ importance. They may become positively identified with one of these stages of the Tertiary, and for this reason, in.order that the means of comparison may be more easily recognized, I propose to modify the 4 Ree] PALEONTOLOGY—LIGNITIC FLORA—AGE, 367 plan of my former reports in the following manner: The specimens ex- amined from the exploration of past year (1873) will be described in separate sections or groups, to which are referable the localities where- from they are derived; and instead of placing in a single synoptical table all the species known from our American Tertiary measures, it will be more appropriate to prepare a table for each of the Tertiary stages, aS recognized above; reserving a general table for a later time, when our Tertiary divisions are more positively recognized. It is to this last end especially, and as stated above, that these different tables may be useful. The materials which we have now on hand are abun- dant enough to point ott a marked difference in the vegetation of the different horizon of the Tertiary, though the general characters of the separate groups which they represent are not yet well determined enough to give positive evidence in regard to the exactness of these divisions. As our Tertiary measures are of wide extent, and are likely to become more and more carefully studied, these different tables will afford points of comparison for local floras, and therefore for identifi- cation of local formations, just as, in the former reports, the general tables furnished for the comparison of the geological epochs, the Creta- ceous and Tertiary, an evidence which is needed no more; for, indeed, I believe that from the descriptions, details, and expositions of the characters of each of these separate groups of the Tertiary, its age and its disconnection from the Cretaceous will be established positively enough to prevent any further discussion on the matter. §1.—AGE OF THE NORTH AMERICAN LIGNITIC. Besides the evidence furnished on the age of this formation by the characters of the vegetable remains, I have, in my former annual report to Dr. Hayden, drawn some collateral conclusions, which I wish to briefly review now, in order to separately consider, in regard to them, any new evidence afforded by the researches of 1873. These conclusions were taken, 1st, from the fact of the immediate superposition of the strata bearing plants to well-characterized strata of the upper series of the Cretaceous, the Fort Pierre and the Fox Hill beds of Hayden’s section, in the Report for 1871, (p. 87.) This immediate su- perposition of the heavy fucoidal sandstones and of the Lignitic over Upper Cretaceous rocks, is seen in full evidence, as remarked in the re- port, in the Raton Mountains of New Mexico, around Trinidad; all along the ridge of sandstone from Trinidad to the Spanish Peak; at the Cation City coal-basin under the Lignitic formation, as marked in the section of Mr. Nelson Clark, superintendent of the coal-mines; at Colorado Springs, in following the bed of Monument Creek, from the depot to Gehrung’s coal; at Golden, Marshall, &c. On this subject my observations agree with those formerly recorded by Dr. Hayden, Dr. Leconte, and others; the succession of the strata has been recognized by all the geologists. 2d. I have not denied, and do not deny now, the presence of animal Cretaceous remains in the strata of the Lignitic, though persisting to con- sider the formation as Tertiary notwithstanding; for Iregarded and still regard the presence of some scattered fragments of Cretaceous shells as of little moment in comparison with the well-marked characters of the flora, characters which have been fully established by a large number of specimens obtained from all the localities referred to the Lignitic. I re- marked, however, on the scarcity, if not the total absence, of Cretaceous animal remains in the whole extent, of the Colorado basin, from the Ka- ton Mountains to Cheyenne. Since then, new evidence has been supplied to this subject, first by a : . 368 GEOLOGICAL SURVEY OF THE TERRITORIES. letter of Prof. H. T. Cox, who, in company with Dr. R. Owen, found specimens of Scaphites and Inocerami in strata supposed to belong to the Cretaceous Lignitic, as quoted by Dr. Leconte in his Notes on the Geology of the Union Pacific Railway, (p. 19.) Professor Cox says, con- cerning these specimens, which are still in his cabinet— I copy from my memorandum-book the section and notes made at Spanish Peak, a range of the Rocky Mountains, from a stage-station on Purgatory Creek. Cretaceous. Isom Ibeyngl oo d50 coScun Goeens sadetodanceaussdunooedes nosue eco sed CbopSelcoEs 20 feet. Thin and thick bedded sandstone, Schistose sandstone and shale, soco asad bgoEeO o20000 Jocag0 casdag sascoas 200 feet. Solid bedded sandstone. {Naha COM Sassy oecaus soSdoonouaisa esos cecceuineonedoobc ceso dado pood go5oKe — Solidvonitawwibhpebblesmas- ses -lseet-eee eee cae ce eater pbdonee Sa0c 70 feet. Ma US ya bi DASE 25 nists stab cis ol sia ole ere Rh Sre te ee ee wie ce Stes de ee Pe eyeie ce ate rere ee lore ota eine et ceete 400 feet, The talus rested upon the table-land, which is 240 feet above the bed of the creek ; total height, from bed of creek to top of section, 930 feet. The ridge extended back from face of hill, and appeared to be about 100 to 150 feet higher.—(Note on section from memorandum-book:) Found in the wash at foot of talus in the above section, Scaphites nodosa, and a species of Inoceramus. The section is similar to those given in Hayden’s Report for 1872, (p. 319), of the Lignitic and its underlying heavy sandstone, on the Purgatory Creek, near Trinidad, which is underlaid by a talus of Cretaceous black shale, No.4. It compares especially well to my own, in the same report (p. 320), of the range opposite Trinidad, where the underlying black and Cretaceous shales and covered space to the bed of the creek measure 300 feet. From this place, and along the stage-road to Spanish Peak, the distribution of the strata is the same, the heavy Lignitic sandstone tow- ering over the talus of the black shale, like a wall, as reported, (loc. cit., p. 321,) and overlaid by the beds of lignites, or the productive Lignitic. That, therefore, the Cretaceous fossils found at the base of the talus of black shale No. 4 do not prove that the Lignitic above is of Cretace- ous age is evident enough. The section of Professor Cox, on the con- trary, confirms the deductions taken in relation to the superposition of the Tertiary Lignitic to the Cretaceous in that part of the country. The authority of Captain Berthoud, of Golden, has been often quoted on the same subject, and is generally considered as of great weight in geological matters of Colorado, a region which this gentleman has for many years surveyed for the construction of railroads and carefully examined with the eye of a practical geologist. He has been reported as supporting the assertion that Cretaceous mollusks had been found above the beds of’ the Lignitic formations. In regard to my inqui- ries on this subject, he had, like Professor Cox, the kindness to give his detailed opinion in a letter, whose statements are worth preserving. He Says, 1st. That if Professor Stevenson observed Inocerami, Ammonites, Scaphites, Baculites, Nucule, &c., in superposition to Lignitic strata of Colorado, it is clear to me that it is only a case of local inversion; i. ¢., that, as shown in our basin of Golden, the Lignitie sandstone has been so tilted up that, with the coal-seams near by, it was thrown over the perpendicular, and thus Cretaceous strata would appear in superposition. 2d. That between this Lignitic and the Cretaceous beds holding Jnoceramus, &c., on Bear Creek, there is fully one mile on an east or west line, so that the Cretaceous beds and the Lignitic coal-shale, fire-clay, and sandstone are not conformable in dip, and clearly show the superposition of the Lignitic beds. This is undoubted, as the Cretaceous limestone debris, under green and yellow clay-beds, disappear under the coal- beds at our old camp on Bear Creek that you visited with me. At Golden I cannot see that the Cretaceous beds are conformable to the sandstone and coal; so far I wrote to A. R. Marvine. Now,I will add to this for you some other remarks. It has always seemed to me a stumbling-block when ten years ago, or more, and until 186869, I supposed and believed that our coal was Cretaceous, to find every- where, when examined by me, that there was no conformability between the Lignitic Measures and the outcrop west; and that at Ralston, Bear Creek, Table Mountain, the PALEONTOLOGY—LIGNITIC FLORA—AGE. 369 LESQUEREUX.] stratification was also unconformable to all from the coal westward. But when I find. that as we proceed, east, the superimposed Tertiary beds are getting more and more horizontal, and that in the clays and sandstones above the coal, we see a well-developed resemblance in fossil ‘plants up to the basalt overflow, I gave up the idea of the Cre- taceous origin of this Lignitic, and the possibility that a salt-water deposit could belong to the same geological horizon, as indicated by the Tertiary fresh-water deposits, par- ticularly as the conformability of this coal and this Cretaceous limestone can nowhere be shown. As to Dr. Leconte’s report of what I found east of Pike’s Peak, it is in the main true. I found coal when on ascout. I judged it was nine feet thick. It seemed almost horizontal, but I would not say it was horizontal, as it was badly cut up by the drainage of the small gully we found itin. In blufis north or northwest I found several Baculites that seemed to come from a clay-bed in the bluffs; but whether this coal was superimposed to this baculite clay, or the clay was over the coal, I could not say positively either way. Southwest of this locality, twenty-five miles, omthe Arkansas, the Baculite clay-beds are below the Inoceramus limestone, and no coal whatever above. 3d. The coal-bed opened near Platte Cafion I have not yet seen. I know that fine Baculites and Scaphites have been obtained there, said to be near the coal, but have no evidence of it; will visit and report to you, as soon as I can, just what I find there. But I think it is a case of local inversion, as the coal, to within three and one-half miles of South Platte River, is tilted up the same as at Bear Creek, Golden, Ralston, &c. Elevén miles north of Golden, on Coal Creek, these Lignitic beds are regularly inclined east, and no Cretaceous beds west of them can I find. At Murphy’s coal-mine no Cre- taceous fossils are found east of the coal. In Golden, cutting a deep well in the green Tertiary clay about 1,000 feet east of the coal has exposed a stratum of deep-green clay, with a large deposit (leaf-bed) with leaves changed into glossy coal. They seem to belong to Salix, Platanus, Khamnus, &c.; a gramen, also a small fragment of an elytra, or wing-case of aninsect. The fossil beds near Bowlder County are accompanied with clay full of casts of leaves, of sedges and grasses, mollusks, fossil turtles, and one or two bones that Professor Marsh thinks are Dinosaurus: This is sufficient to show that, except the specimen of Inoceramus found by Dr. Leconte at the Raton over.Lignitic beds, no Cretaceous fossil mollusks have been found till now in the whole Lignitic basin from the Raton Mountains to Cheyenne. 3d. To answer the objections that at Black Butte, Coalville, Bear ‘Biver, and other localities in Wyoming, the Lignitic beds and sandstone bearing plants had been recognized underlying strata*with fossil remains of Cretaceous animals, I had to examine if, from its nature and its fossil plants, the Lignitic formation should be of necessity recognized as a whole, or if it could be separated into different members, the one repre- senting the Upper Cretaceous, the other the Lower Tertiary. For this, of course, the essential Gocuments to be considered in the view of my special researches are the fossil plants. From the large number of Fucoids in the sandstone, and from the identity of some of the species of these marine plants found by Professor Meek, even in connection with the lower strata of the Lignitic as far down as the arenaceous beds of Bear Creek and Coalville, with Cretaceous animal remains; from the prodi- gious preponderance of palms, leaves and fruits, recognized also in the same circumstance, &c., I forcibly admitted the unity of the Lignitic formation in its whole, and therefore limited the discussion to this point: the Cretaceous or the Tertiary age of the formation. The detailed exam- ination of the fossil plants of the Lignitic and of their distribution affords more evidence on this question. 4th. To strengthen my position in regard to the conclusions afforded by vegetable remains, I compared the Lignitic formations to those of the Carboniferous epoch, remarking that, having positively a preponderance of land-plants or a land-character, they should be considered as a land- formation ; that in every formation, especially in every land-formation like that of the Carboniferous, the fossil animal types are more or less in discordance with the vegetable forms in regard to the data furnished by them on the age of the formation. As in the Carboniferous we find Devonian mollusks far above the millstone-grit, and also Permian shells far below the Permian, and as the Carboniferous is now generally recog- 244s — 370 GEOLOGICAL SURVEY OF THE TERRITORIES. nized as a homogeneous single formation, I argued that, the same dis- accord being remarked in our Lignitic measures, we had to explain it in the same way, and should not, on that account, force an abnormal divis- ion of a formation whose flora is positively analogous or synchronous in its characters in the whole thickness. A discrepancy of the same kind is recognized in the Cretaceous formations of Europe, even between the groups of animal fossils which characterize them. ‘The. president of the Society of Natural History of Geneva, my honored friend, Rey. Duby, says, in his discourse of 1861, in regard to the geological observa- tions recorded during the year, That the society had been favored by Professor Pictet with numerous communica- tions relative to paleontology, of which the most important is a notice of the succes- sion of the cephalopod mollusks during the Chalk period in the region of the Swiss Alps and Jura. Mr. Pictet derives, from a detailed study of the fossils contained in the Cretaceous strata and their comparison with contemporaneous repositories, an argu- ment in favor of the idea propounded by Mr. Barande, that two successive faunas must necessarily have existed together for some time, and he concludes by showing that paleontological faunas, distinguished through by marked characters, are net ordinarily susceptible of any rigorous limitation. Messrs. Claparéde and Favre took occasion to remark on this, how much the conclusions of Mr. Pictet must in future complicate the task of geologists who undertake to determine the age of the formations. On the same subject Count Saporta, one of the highest European authori- ties in vegetable paleontology, remarks,* in speaking of the presence of Ammonites, Baculites, Inoceramus, &c., in the American strata, which, by their fossil plants are characterized as Hocene, that these mollusks have persisted for a longer time in the Cretaceous of America than in Europe; a fact which is easily admitted, as, in France, the chambered cephalopods had leit the Cretaceous seas of the south long before they disappeared from the north. The same remark is repeated in Jukes and Geikie’s Manyal of Geology, (p. 664.) In parts of the north: of France there occur curious banks of white pisolitic lime- stone, resting apparently in hollows of the chalk, &c., but sometimes on the same level as the lower beds of the Tertiury rocks above it. Some oi the*fossils are true Creta- ceous, while none, I believe, are Tertiary forms. We have apparently something like thisin our geological Upper Creta- ceous formation, if, as it seems proved, we do not find any kind of Cre- tacecus mollusks in the Lignitic basin of Golden, when their presence is still ascertained in the Lignitic of Bear River and Coalville. The English geologists remark on facts of this kind, (lec. cit., p. 665:) That the existence of local groups of rocks that will not exactly fit into the general series, either from their containing fossils different from those found in any other group, or from their uniting parts of two sets of fossils which are elsewhere distinct, although sometimes perplexing, seems neither unnatural nor different from what might be expected. It merely shows us that our geological series is a series of fragments, not one of absolutely continuous succession. In his travels with the Hassler, Professor Agassiz has observed a - case which may serve to explain anomalies between the records fur- nished by animal and vegetable remains in regard to the age of the strata.t The geology of the coast of Possession Bay is interesting to the highest degree. All along the coasts, north of the Straits of Magellan, the Tertiary formations, same as — along the coasts of Eastern Patagonia, are perfectly distinct, even seen from a distance, by their horizontal strata, also remarked on the coast of Fuego. In Possession Bay we. landed to more carefully recognize the character of the country, &c. One mile inland from the cliffs I found, at 150 feet above the sea-level, a pond of salt water, which, to my great surprise, had an abundance of marine shells, identical with those of the sea along the coast. They were in a perfect state of preservation; many were living, * In letters. t Letter of Professor Agassiz to Professor Peirce, in Boston Advertiser. I have to re- translate this from the French Revue scientifique, No. 46, May, 1873. tusquerevx.) 1 PALEONTOLOGY—LIGNITIC FLORA—AGE. at and I could collect a large number of specimens, with living animals, for preserving in alcohol. The most numerous were Fuci, Buccini, Vissurelle, Patelle, Volute, &c., all in the same numeric relation which was remarked in the sea under the cliffs. The pres- ence of this salt pond, with its living inhabitants, proves a very recent upheaval of the coast. The exact time could not be precisely fixed without a more extensive geological examination. The fact is the most complete confirmation of Darwin’s assertion, pub- lished more than thirty years ago, that there has been a recent upheaval of the coasts. Admitting the fact as it is exposed by Professor Agassiz, and sup- posing that, after an epoch of time, there should be a contrary, slow movement or depression of the same land, and that from the start this depressionsshould be accompanied by the introduction of fresh-water lakes, of swamps, &c., the growth of extensive bogs, and the formation of peat-beds by plants; that over it a succession of shales and sand- stone should be formed by more rapid depression and the invasion of muddy or sandy water, &c., the result of this heaping-up of new mate- rials would represent, of course, a more recent formation, characterized by its remains of fossil plants, this, under or below the level of a more ancient one, characterized by its fossil invertebrate animals, &c. 5th. In recording the opinions of geologists, who, by their researches, have furnished materials (animal fossils) as evidence of the Cretaceous age of the Lignitic, I quoted Professor Meek’s passage of a letter, where his opinion is exposed rather in favor than in contradiction of mine. Of course, I was not then informed of his conclusions published later. We have now, in the report of Dr. Hayden for 1872, (pp. 431-462,) the re- sult of the researches of this careful observer, tending to prove that the Lignite deposits of Coalville have been positively recognized underly- ing strata characterized as Cretaceous by their remains of mollusks. As nofossil plants have been discovered in connection with these coal-beds, except the omnipresent fucoid, Halimenites major, no argument can be put forward from the comparison of vegetable fossil remains. Itis, however, remarkable that the constitution of the Lignite of Coalville, the thick- ness, the distribution of the beds, is about the same as that of Evanston ; so similar, indeed, that the more experienced miners and superintendents of the mines at Evanston and other places consider these Lignitic beds as the same. The difference of fixed carbon in the lignite of the two localities is only 1 per cent.; that in the proportion of water, only 2; in volatile matter, only 3. And if we admit that the chemical compound of the coal and the lignite, like that of the peat, depends especially from the original constituents, the plants, we have in this fact of identity of chemical compounds more than a probability of a homogeneity of original or vegetable components. In this case the discussion is recalled to this point, as remarked above: the whole Lignitic being a homogeneous formation, we have to decide if it is Cretaceous or Tertiary. The locality where the discussion on the relation of fossil remains may be made with the most advantage is that of the Bitter Creek Series, where there is an abundance of vegetable remains repre- sented, at Black Butte especially, and of animal fossils, saurians, shells, &c., also found in profusion in the strata of this series from Black Buttes to Rock Springs. In the whole series, neither Professor Meek nor his assistant have found any shells truly characteristic of Cre- taceous age; and Professor Meek says himself, (p. 458,) “‘ that although partly committed to the opinion that this formation belongs to the Ore- taceous, and still viewing it as most probably such, he does not wish to disguise or conceal the fact that the evidence favoring this conclusion, to be derived from the mollusks alone, as now known, is by no means strong and convincing.” As from the flora of Black Butte we do not have any identical or intimately related species to the Cretaceous plants, as all the types are Tertiary, even a large number Miocene, the conclusion 372 GEOLOGICAL SURVEY OF THE TERRITORIES. is forcibly in favor of the Tertiary age of the Lignitic. Nearly one-half of the species of fossil plants found at Black Butte are identical with or closely related to Eocene and Miocene species of Europe. On this subject even the invertebrate animals seem to point out to the same conclusions; for Professor Meek remarks, (loc. cit., p. 460,) “ that he found directly associated with the reptilian remains of Black Butte (that saurian imbedded in Tertiary leaves) a shell which he cannot dis- tinguish from Viviparus trochiformis, originally described from the Lig- nitic formations at Fort Clark, on the Upper Mississippi, a formation that has always been regarded as Tertiary by all who have studied its fossils, both animal and vegetable.” The whole discussion on the subject, continued by Professor Meek, and reviewed clearly on the following pages, (pp. 461-462 .) establish the same fact, that paleontological evi- dence from remains of invertebrate animals is rather in favor of the Tertiary than of the Cretaceous age of the group. The conclusion of Professor Cope amounts to this: that from the Da- kota group to the top of roof of the Black Butte main coal he met with an uninterrupted series of animal Cretaceous remains, mollusks in the lower beds and vertebrates in the higher, proving that the beds are Cre- taceous(!). Comparing this with the flora of the Lignitic, he concludes that a Tertiary flora was contemporaneous with a Cretaceous fauna, establishing an uninterrupted succession of life across what is generally regarded as one of the greatest breaks in geological time. This conclusion does not appear to exactly conform to facts, at least on the point of view of vegetable paleontology, for on this account, and contrary to what is remarked by Professor Cope in following his re- searches on the bones of extinct species of animals, we have from the Dakota group to the lowest strata of the Lignitic, or to the same bed at Black Butte, where the bones of that dinosaurian were found, an evi- dent and total break in the succession of vegetable type, quite as marked as it can bein passing from the Jurassic to the Cretaceous. This anomaly may be explained in considerinig this fact: that the flora is in direct collateral relation with atmospheric circumstances which do not influence, at least not in the same way and with the same activity, the marine world and the land vegetation. Morever the lower Hocene of Europe has a series of clay beds bearing remains of land plants. They are intermediate, it seems, between the upper Cretaceous and the Lignitic formations, and thus indicate long periods of time sufficient to account for great modifications in the flora. 6th. Leaving aside these considerations, which bear indirectly on the subject, I have to come back to the question of the precedence which in a case like this should be accorded to fossil plants, for the determina- tion of the age of the formation; for I cannot leave without contra- diction @ critical remark made against the report of last year, whey among others, says :* Mr. Lesquereux has met the statements of Professors Meek, Cope, and Marsh, that Cretaceous mollusks had been found in and overlying the Colorado lignite deposits, by pointing to his 250 species of fossil plants, claiming that they far outweigh the tes- timony of the animal remains. In fact, however, these fossil plants have little bear- ing on the question. _ The absence of fossil mollusks in the Colorado basin has. been proved; ‘but even admitting the contrary, and taking as an analogous case the i coal of Black Butte, over which the skeleton of a dinosaurian, Agathauma sylvestris,t has been found imbedded into leaves of Eocene plants, shall we tor the reason of the presence of these Cretaceous remains, still more *Dr. Newberry, in Journal of American Arts and Sciences, vol. vii, April, 1874, p. 403. 1 Cope, Second Bulletin of the United States Geological Survey. tesqurrrvx.| 4 PALEONTOLOGY—LIGNITIC FLORA—AGE. 373 important as characteristic than mollusk, admit the formation as Creta- eeous, and consider the plants as without bearing on the question? I have last year spent some days at Black Butte and in the surrounding ' country, and may here record the observations which, related to this question, may not find their place elsewhere. The Saurian bed, as it is now called, is at the top of the ridge facing the depot, at a short distance, half a mile east from it. The débris taken out in digging the bones of the animal are still mixed with a quantity of fragments of these bones, and some of the specimens are remarkably interesting, bearing as they do, fragments of bones on one side and fossil leaves on the other. The bed is a kind of arenaceous clay, mixed with ashes, and hardened to the consistence of brick by the combustion of the underlying beds of coal. It overlies, east of the station, three alternate ridges of whitish weathered sandstone of: the thickness, taken altogether, of 96 feet, being 10 feet 8 inches above the upper ledge, which is a compact, white, hard sandstone, 10 feet thick, and is exposed and can be followed easily to the south for about a quarter of a mile, where the main coal-bed of Black Butte is worked. At this place the section in descending order is: 12. Fire-elay and shaly sandstone, 9 feet. 11. Yellow sandstone, 6 feet. 10. Shale and coal-brash, 1 foot. 9. Shaly sandstone and plants, 12 feet. 8. Coal, 3 to 5 feet. (. Fire-clay, 2 to 7 feet. 6. Main coal, 5 to 7 feet. 5. Fire-clay, 5 feet. 4, Clay, capped with slaty sandstone, 5 feet 4 inches. 3. Coal, 3 feet. ' 2. Shale and clay, with oysters, 7 to 10 feet. 1. White sandstone, 10 feet 8 inches. . This sandstone, being the same as the upper sandstone under the Saurian bed, the former section shows the exact horizon where the bones have been found as within or above the lower 3-foot bed of coal No. 3, separated by 10 feet of fire-clay from the main Black Butte coal. It is very probable that both coal-beds disjointed, at the locality of the Saurian, by a mere clay parting, were destroyed by fire under the stra- tum of clay. Anyhow, I did not find in connection with the bones any species of plants differing specifically from those found in the sandstone No.9 abovetheuppercoal. Thespecimensrepresent Sabal, Viburnum dicho- tomum, Hicus planicostata, Myrica Torreyi, Aleurites eocenica, Paliurus gizyphoides, some stems, Cauwlinites, and fragments of leaves of a Pla- tanus, whose middle part only is preserved, and which may be referable to P. Haydenii, the only kind of plant which was not recognized in the Shale of the main coal. The case is clear: from all the fossil plants described from Black Butte none is referable to a Cretaceous species ; they are all Tertiary, and force the admission made by Professor Cope in his review (loc. cit., p. 16) that here a Tertiary flora is contemporaneous with a Cretaceous fauna. Now, this flora is typical for the compounds of the coal-strata, and, of course, the coal-strata are Tertiary. What Shall be the name of this formation ; is it Cretaceous on account of the Saurian bones, or is if Tertiary on account of the fossil plants in which the skeleton is entombed, and which are found of the same relation all over the Lignitic formations, and at some places, as at Golden, the Raton, &c., from its base to the upper strata, and which two have entered into the composition of its essential strata, the Lignite? No geologist, I think, will hesitate a moment in pronouncing it, from its 2 374 GEOLOGICAL SURVEY OF THE TERRITORIES. land-character, a Tertiary formation, therefore giving the precedence to the fossil flora over the fossil fauna for the determination of the age of this formation. It is, then, evident that the fossil plants have some weight and must decide. 7th. This brings me to the essential question which has to be exam- ined in considering the relation of the age of the fossil plants of the Lower Lignite of the Rocky Mountains. Though the flora is evidently related to that of the Tertiary of Hurope by a large number of its species, it is, however, difficult to point out with uncontestable evidence to what stage of this Tertiary the relation is the more intimate. To come to an understanding on this subject, we have to compare the American fossil species with those known as yet from the publications of European authors, and at once are met with a scarcity of materials, especially from the Lower Tertiary strata or the Eocene, to which, considering the position of the Lignitic, its flora should be especially related. The Tertiary of Europe seems to have been, as expressed by Dr. Ettinghausen in his Contributions to the Radoboj Flora, ‘a kind of universal vegetable repository, representing types of all the regions of the world; a seminarium, which hereafter dispersed its offsprings over the whole surface of the earth.” This conclusion is not my own. I should only say that the European Tertiary formations have been the recipient of species representing an heterogeneous vege- tation, type of multiple and local changes. But this matter is out of the subject; we have only to record the fact that, so mixed in their facies are the floras of the Tertiary basins of the Oid World that as yet no reliable delimitation has been established for the stages which they represent.” In considering the characters of our Lower Lignitic flora, a critic has -asserted that its genera are all, as well as the species, without relation to Eocene vegetable types of Hurope, quoting as a proof of his assertion the flora of Mount Bolea, and that of Shepey in England. This last flora is merely known by fruits whose forms or species have been de- scribed and figured by Bowerbank, and which are heaped in prodigious quantity in the so-called London clay of England. This Eocene flora, however, cannot be taken for America any more than it has been for Europe as a point of comparison, for it has no leaves, and its fruits, of various and uncertain affinity, have as yet not been found elsewhere in the Tertiary of Europe, except a few Nepadites, merely mentioned (not described yet) from the Eocene of Mount Bolea. These Shepey iruits, as Heer remarks, are not characteristic of the formation, even say noth- ing in regard to the climate of the locality where they are found, as, from appearance, they have been floated down some river for a great distance, and are analogous to present deposits of this kind at the mouth of the Ganges. The Eocene flora of the Isle of Wight, at Alumbay, is repre- sented by numerous leaves of Avralia, Daphnogene, Ficus, Zizyhus, Cesal- pinia, &c., which, according to Heer, have such a marked tropical and subtropical character that the fruits of Shepey may have been derived from the plants of this locality. These Alumbay leaves, to quote the same authority, are similar to species of Mount Bolea ; three species are identified as the same, and three others are closely related. But also a number of them are Miocene; as, Quercus lonchitis; Laurus primi- genia; Myrica (Diandra) acutiloba ; Cassia phaseolites; or four species, * Since writing this, the third and last volume of W. P. Schimper, Palontologie végéiale, has appeared. The author, considering the vegetable groups of the Tertiary, divides the formation in the five following stages: Paleocene, intermediate to the Cre- taceous and Tertiary ; Hocene, Oligocene, Miocene, and Pliocene. The relation of our Lig- nitic vegetation seems to ke with the Oligocene. tesqurrevx] PALEONTOLOGY—LIGNITIC FLORA—AGE. 75 (Sys) and four other species, Laurus Forbesii, Daphnogene anglica, Quercus Burmensis, and Juglans Laharpii, are related to Miocene species in the same degree. From this, it seems, the conclusion should be in favor of a more intimate relation of the fiora of Alumbay, which is posi- tively recognized of Hocene age, with that of the Kuropean Miocene than with that of Mount Bolea; for it has only six species identical or in relation with the Mount Bolea flora, while it has eight, bearing the same degree of relation to the Miocene. Some of the species of the North American Lignitie are identical with or closely related to those named by Heer. Quercus furcinervis is probably identical with Q. Burmensis ; for,. in many of the numerous American specimens of this species, the absence of an upper branch of the lateral veins, which, according to Heer, is- the essential character which separates these two species, is positively remarked. Daphnogene anglica, is as positively identified as it can be from the short description given by Heer, it being different from D. melasto- macea by the symmetrical form of the leaves and the branching of the lateral nerves. Heer says that the middle nerve is also branching. In our specimens it is simple; in Unger’s species neither the lateral nor the middle vein branches. Though these species re-appear in some forms of the Miocene of Europe, they should be considered, I think, rather as Eocene than as Miocene types. The Mount Bolea flora is represented by a large number of specimens of leaves and fruits disseminated in the numerous museums of Italy. Until now few of the species which they represent have been satisfac- torily described. The little which is known of this flora is from the table of families furnished to Professor Heer by Professor Massalongo, and published with remarks in Fl. Tert. Helv., (vol. iii, p. 275.) This table has 53 groups ef plants, among which the more numerously repre- sented are: Alga, 48 species; Podocapee, 5; Palms,7; Proteacee,5; Hrica- cee, 10; Sterculiw, 10; Buttneriacee, 14; Myrtacee, 8, &c.; and among the species the most abundant, Hucalyptus Italica, Mass. ; Hugenia laurifolia, Mass. ; Guayacites Heerti, Mass.; Zanthoxylum ambiguum, U.; Ficus Bol- censis, Mass., which Heer says is similar to /. multimervis of the Miocene; Santalum memecyloides, Mass.; Aralia primigena, de la H.; in ali ten species not described but briefly remarked upon by Heer. From the characters of the Mount Bolea flora as indicated in this exposition of Heer, it does not appear, indeed, that our Lower Lignitic flora has any marked relation to it; but the scantiness of materials, together with the uncertainty of the characters of a number of species named by Massalongo, renders a comparison impossible. Heer himself, in his ex- position, remarks on this insufficiency of reliable characters. He, for example, counts only four species of Mount Bolca as represented in the Miocene of Europe, and a few more as closely related to Miocene species. He mentions among those ascending to the Molass of Switzerland, Banksia longifolia and Dryandra Veronensis, two species which have close relation with species of our Upper Miocene, the Green River group, rather than with species of the Lower Lignitic. Since Heer’s short review of the Mount Bolca flora was published, in 1859, paleontology has not received any more precise information in regard to its characters. Schimper, in his Vegetable Paleontology, 1873, mentions only from this locality, besides 21 species of marine plants or fucoids, Cyperites Bol- censis, Mass., considered or described formerly by the same author as a Flabellaria; Halochloris cymodoceoides, Ung., also found at Soltzka ; Pota- mogeton tritonis, U., and P. nayadum, U.; Typha spade, Mass., a species which Schimper supposes to be made from the leaves of some Cyperacee ; five forms of Castalline, fruits comparable to the Nepadites of the Lon- don clay, representing probably a single species; Latanites parvulus, 376 GEOLOGICAL SURVEY OF ‘THE TERRITORIES. Mass., a palm ; Lomatia Bolcensis, U.; L. latior, Heer, of which a smali broken part is figured in the Baltic Flora, and to which one of the most abundant species of Black Butte Myrica Torrey, Lesqx., so much resem- bles by its peculiar nervation and by the form of the leaves that bet- ter specimens only of the European plants can decide between positive identity or a very close relation ; Myrica Meneghint, U., of a type repre- sented with us in the Upper Tertiary of South Park; and Daphnogene Veronensis, Mass., which Schimper compares to Cinnamomum Scheuch- geri. This is all that is positively known of the flora of Mount Bolca. It is impossible to consider it as a kind of typical flora of the Hocene of Europe, and to assert that if we cannot point out any of our Lignitic species as identical with this flora, it is for that reason deprived of the . character of the Hocene vegetation. France has in the deposits of the old Travertins of Sezane a number of species whose types seem to be intermediate between the Cretaceous species and those of the Upper Eocene. This flora is known by the admirable work of Count Saporta,* who describes in it a Sassafras comparable to S. Mudgii, and leaves of Magnolia, related to M. alternans and M. capellini, three species described from the Dakota group. A number of forms of this Lower Eocene flora are also related to the Ter- tiary species of Europe, especially to those of the Mount Promina flora; and with our Lignitic flora it has closely allied two of the more charac- teristic and more abundant species of Black Butte, Sterculia variabilis, Sap., distinguishable only from Ficus planicostata by the unequal lateral base of the European leaves, and the beautiful Viburnum giganteum, related, by its size and nervation, to V. marginatum. Besides this, it has Asplenium subcretaceum, Sap., intimately related to the species which I have described as Sphenopteris eocenica, most abundant at Golden ; Cissus primeva to C. lobato-crenata, also abundant at Black Butte and in the Colorado Lignitic basin, Mount Brosse, &c.; Cornus platiphylla, re- lated to OC. impressa. These all show affinity indeed to a flora so posi- tively marked as Lower Hocene, that some of its types are still Cre- taceous. I have admitted, as indication of the Hocene age of our Lignitic flora, the great abundance of fucoidal remains, or of marine plants, in the underlying sandstone of the Lignitic, a character remarked in the sand- stone of Mount Bolca, and also of the Flysh of Switzerland. One of the © few species which I have as yet been able to describe, from the difficulty of obtaining specimens, Halimenites minor, is known from this last for- mation. Besides this, a comparatively large number of species of ferns, some of them identical with species of Promina: Goniopteris polypodioides, Ktt., and Sphenopteris eocenica, or with that of Boernstadt: Diplazium Mueller; then a great proportion of remains of palms, referable to as many species as have been described from Europe at least, some of them identical with species of Promina, Boernstadt, Haring, representing, like Flabellaria latania, &. longirachis, #. Zinkeni, some of the more ancient forms of palms recognized in the Ctenzoic times. Theremarkable prepon- derance of palm remains bas been mentioned from all the stations of the Lower Lignitic where fossil plants have been discovered: Vancouver, Fort Union, Black Butte, Golden, Sand Creek, Gehrung’s, Cation City, Raton Mountains, Placiére, the Mississippi, &c. They have given to the vege- tation of the epoch a subtropical character, marked still by a number of species of Ficus of the broad-leaved and palmately-three-nerved group, most of them new species, and none of the typeof the lanceolate-pinnately- nerved leaves like Ficus lanceolata, F. multinervis, &c., which, with us * Prodrome d’une flore fossile des Travertins anciens de Sezane, (1868.) tesquerevx.) PALEONTOLOGY—LIGNITIC: FLORA—AGE. OTT at least, represent types of the Upper Miocene only. Among species of the other genera of Eocene type, the Lignitic flora has still Myrica Torreyi of Black Butte, possibly identical, as seen above, with a Lomatia of Mount Bolea; three species of Platanus: P. Haydenti, P. Raynoldsi, P. rhom- boides, without any affinity with any of the Cretaceous or of the Miocene species known as yet; Artocarpidium olmedicefolium, U., described by the author from Sotzka; a fine new species of Pisonia, P. racemosa, allied to P. eocenica, Ktt., of Haring, as well by the seed (or unopened buds) as by the leaves; Daphnogene anglica (?), which has been remarked upon as found at Alumbay; two species of Nelumbium, related to N. Buchi, Ett., of Promina; Hucalyptus Haringiana, of Haring; Dombey- opsis grandifolia, U., of Sotzka; a number of species of Rhamnus of a peculiar type, comparable, by the form of the leaves and the nervation, to tropical species of Bridelia. These can be considered as already giving to the flora of the Lignitic, in comparing it to that of Europe, an Eocene facies. But we have in America a more reliable point of comparison, still. forcing the conclusion that if even the Lignitic flora of the Rocky Mount- ains had no relation whatever to that of Europe, it should, notwith- standing, be considered as Hocene. I allude to the flora of the Missis- sippi, described from very good specimens obtained from such a lower stratum in the Tertiary that its reference to this formation rather than to the Cretaceous was for a long time uncertain. In the Geological Re- port of the State of Mississippi, Prof. Kug. V. Hilgard has given (p. 108) a section of the general distribution of the strata in the geological for- mations of the State, marking the place of the Lignitic of the Missis- Sippi State and of the formations where his fossil plants were found as underlying the Vicksburgh and Clayborne beds, which form the upper stage of the American HKocene, the Lignitic representing the lower one: The correlation of the Mississippi fossil flora with that of Golden and of Black-Butte is evident enough. Of the Mississippi plants, the fol- lowing have been recognized in the Western Lignitic: Sabal Grayana, Vancouver; Populus monodon, Raton Mountains; P. mutabilis, Black Butte, Raton Mountains, Vancouver; @uercus chlorophylla, Golden; Quercus crassinervis, Vancouver ; Ficus Schimpert, intimately related to F. platinervis, as widely represented at Black Butte, Golden, &c., as the former is in the South; Laurus pedata, Raton Mountains; Cinnamomum -Mississippiense, one of the most prevalent species of the Western Lig- nitic; Magnolia Hilgardiana, Raton Mountains; If. Lesleyana, Raton and Golden. This, without mentioning a number of closely-allied spe- cies and the identity of genera, gives to both the floras of the Mississippi and of the Western Lignitic formation a general character which can but be recognized as identical. After all this, we remark in our Eocene flora some characters which may be called negative, namely, the absence of certain groups of plants represented either in the Cretaceous or in the upper groups of the Tertiary. No species has been discovered in the Lignitic which had been described from the Dakota group. This is the more remarkable that sonie peculiar types of this group, like Liriodendron, Sassafras, &ec., re-appear above the Lignitic in the Evanston or second group, and in still greater numbers in more recent Tertiary divisions; and that even one of its rare species, Cinnamomum Scheuchzeri, is also absent until now, at least in the lower group, and present in the Same second group and above. Heer remarks, in considering the fossil flora of Mount Bolca, the absence of representatives of a number of genera or families which take an important place in the Miocene, thus: Salicinee, Acerince, Oupulifere, Betulacee, Ulmacen, Abietinee, &e. 5718 GEOLOGICAL SURVEY OF THE TERRITORIES. The absence of these types is as remarkable in the Lignitic flora as in the Eocene of Mount Bolea. While the upper group of our Tertiary abounds with conifers, Abietinew, 11 species in 81, the Lower Lignitic has only two, one as yet of uncertain affinity, Abietites dubius, and two species of Salisburia, in nearly 200 species ; of the Salicinee it has only three species, two of which, Salix tabellaris and S. densinervis, both described from the Mississippi Hocene, are un- certain, the last, perhaps, an Acacia. It has also no species of Acer, none of Betula, Alnus, Carpinus, Corylus, &c.; no species of Ulmus, except one doubtful, with entire borders; for it is, indeed, the absence of leaves with Gentate or serrate borders which is the more remarkable character of this group as well as of the Cretaceous; Quercus furci- nervis and Q. saffordi, (perhaps a Myrica,) make with the Viburnum maginatum and its related species an exception, which is also remarked in the Cretaceous types Q. primordialis and some peculiar leaves with equal teeth turned outside and separated by obtuse sinuses, just of the same form as in this Viburnum of the Eocene. It is not to be denied, as seen in the comparative table, that a number of species of our Lower Lignitic are found in the two following groups of Evanston, Carbon, and even a few in the Green River group. But we have seen the same in the Hocene, even the Lower Hocene flora of Hurope, and cannot from this reason admit that our Lower Lignitic flora is not Hocene, because some of its types have passed up to the other groups of the Tertiary. § 2.—DISTRIBUTION OF THE FOSSIL PLANTS IN THE DIFIER- ENT GROUPS OF THE TERTIARY. The succession of the strata of the Lower Lignitic in relation to the dis- tribution of the coal strata and to that of the fossil plants which character- ize the formation is not positively known. ‘The section at the Raton Mountains near Trinidad records an alternation of sandstone, shale, clay- beds, &c., 300 feet thick, with five beds of lignite, measuring altogether 11 feet 6 inches. Here the fossil plants are found in sandy shale at the base of No. 6 or in the upper part of No. 7 (Report for 1872, p. 319) in the middle of the section. At Cation City, as indicated by Mr. Clark’s section, (loc. cit., p. 323,) the main coal 2 feet 2 inches is overlaid by shale, clay or thin coal, and a sandstone, over which, in No. 15, are found leaves of Sabal and of Platanus Haydenii, about 70 feet above tke coal. At Gehrung’s coal, near Colorado City, a shale bearing an abundance of Sabal leaves, Ficus, Platanus Haydenti, and Rhammnus, is also from 60 to 75 feet above the coal opened near by at the base of a compact sandstone. From Marshall a detailed section has been published by Dr. Hayden in his Report for 1869, (second edition, p. 129,) placing the strata bearing fossil plants at No. 22, aboutin the middle of the section, 200 feet higher than the lower main coal, and about 260 feet from the top. As far as I know, and from the explorations of others as well as from my own, no other strata bearing identifiable plants have been remarked in this seec- tion. At Hrie, the coal 8 to 9 feet is worked near the surface; its soft sandy shale is profusely mixed with remains of plants, which, to my regret, could not beexamined sufficiently. They represent afew species of the Lower Lig- nitic of Golden, and also some remarkable vegetable fragments represent- ing species not found elsewhere. As the underlying strata are not known, the position ofthis coalin the Lower Tertiary measures could not be ascer- tained. At Black Butte, the main coal, overlaid by soft shaly sandstone, with fossil plants in abundance, a stratum which, as remarked before, is the equivalent of the Saurian bed, is here apparently at the upper part A LESQUEREUX.] PALEONTOLOGY—LIGNITIC FLORA, ETC. - 379 of a section of 1,000 feet of measures of the productive lignitic.* In going west toward Point of Rocks, in a contrary direction to the dip of the strata, the Hallwell coal, a workable bed, and other Lignitic beds of unim- portant thickness, are passed until reaching the abrupt terminus of the ridge near Saltwell. Noremains of fossil plants were found in connection with any of these coal-strata. From Haliwell to Rock Springs, the dip of the measures is to the west until the upper strata of Lignitic are reached. Near this last place, a bed of coal 4 feet thick is passed, two miles before reaching the station, and here the main coal, 100 feet higher, is worked 6 to 9 feet thick. I was not able to discov er any: fossil plants in the whole thickness of the measures, and at Rock Springs the coal, which is evidently one of the highest of this group, has not any other plants but the fucoidal Halimenites. Its shale, however, is mixed with a profusion of shells. Considering this, it would ap- pear that the upper beds of the Eocene Lignitic are, in Wyoming, the re- positories of fossil plants. At Golden we have perhaps the best evidence concerning the distribution of the fossil plants in relation to Lignitic strata. The lowest strata of coal, in close proximity to the Cre- taceous, and tilted up to the perpendicular, are interlaid by beds of white hard sandstone, which all, three of them at least in succession, have identifiable remains of fossil plants. The lowest sandstone has espe- cially some species of Fucoids, among which the fine Delesseria fulva, to- gether with a quantity of Sabal, Rhamnus Goldianus, Platanus Haydeniit, Quercus angustiloba, de. Under the basaltic deposits, which cover the Lignitic on the eastern side of the valley, half a mile distant from the Lig- nitic beds, the fossil strata bearing plants are horizontal; at some places composed of soft white clay, as east of Golden, on the slopes of North Table Mountains; at others, of shaly sandstone, as northeast of the School of Mines, on South Table Mountains. These deposits are all about at the same altitude of 300 feet above Clear Creek, 60 to 100 feet lower than the base of the lava-beds. They all contain not only the same types but mostly the same species of fossil plants as the sandstone, inter- lying the Lignitic beds in proximity to the Cretaceous. It therefore appears from this that the flora of the Lower Lignitic has the same char- acters in the whole thickness of the measures. There may be, of course, some difference in the species, or a predominance of some kinds at a higher or lower station, but the difference has not been yet remarked. LIST OF THE SPECIES OF THE FIRST GROUP. [Abbreviations for names of localities, &c.: R., Raton Mountains; P., Placiére; G., Golden; M., Marshall’s; S. Cr., Sand Creek; B. 3, Black Butte; Y. St., Yellow Stone ; Miss., Mississippi; ¥.,; Vancouver ; ; Mo., Miocene; 5 Cre, ee i Spheria lapidea, Tesax. —R. S. myrice, Lesqx.—B. B. Sclerotium rubellum, Lesqx.—G. Opegrapha antiqua, Lesqx.—B. B. Chondrites subsimplex, Lesqx.—R. C. bulbosus, Lesqx.—R. Delesseria ‘fulva, Lesqx.—G. D. incrassata, Lesqx.—R. D. lingulata, Lesqx.—R. Halymenites striatus, Heed —G., R. H. major, Lesqx.—G., R., B. B. , (Gr. 2 2, 3.) * Professor Meek estimates it to at least double this thickness, and considers the lower unproductive strata of this formation as Cretaceous. No evidence is afforded on this subject by vegetable remains, 380 GEOLOGICAL SURVEY OF THE TERRITORIES. H. minor, F. Os.—G. Woodwardia latiloba, sp. nov.—G. W. latiloba, var. minor.—B. B Pteris penneformis, H.—G., Mo. P. anceps, Lesqx.—G. P. affinis, sp. nov.—G. P. erosa, Lesqx.—R. G. (Gr. 4.) P. subsimplex, sp. nov.—G. P. Gardneri, sp. nov.—S. Cr. Diplazium Muelleri, Heer.—G. Aspidium goldianum, sp. nov.—G. Goniopteris polypodioides, Ett.—S. Cr. Sphenopteris eocenica, Ett.—G. S. membranacea, sp. nov.—G. S. nigricans, sp. nov.—B. B. Hymenophyllum confusum, sp. nov.—G. Gymnogramma Haydenii, Lesqx.—R., (Gr. 2.) Lygodium compactum, Lesqx.—Miss. Selaginella Berthoudi; sp. nov.—G. Hquisetum levigatum, sp. nov.—S. Cr. Sequoia Langsdorfi, A. B..—B. B. V.—Mo., (Gr. 4.) Abietites dubius, Lesax. =e, G., (Gr. 2.) Salisburia binervata, Lesqx.—Miss. S. polymorpha, Lesqx.—V. (Gr. 2.) Arundo Goepperti, A. Br.—R.—Mo. Phragmites ceningensis, A. Br.—R., G., M., B. B.—Mo., (Gr. 2, 3, 4.) Carex Berthoudi, Lesqx.—G. Smilax grandifolia, U.-—G.—Mo., (Gr. 3.) S. obtusangula, Heer.—B. B. Sabal Grayana, Lesqx.—V., Miss. S. Campbellii, Ny.—R., G., B. B., &e. S. Goldiana, sp. nov.—G. S. major, U.—G. Flabellaria zinkeni, Heer.—G. F. latania, St.—G. F. eocenica, Lesqx.—B. B. ¥. longirachis, U.—R., Y. St. F. fructifera, sp. nov.—G. Calamopsis Danai, Lesqx.—Miss. Palmacites, species.—G. Caulinites sparganioides, Lesqx.—B. B., (Gr. 2 and 3.) C. fecunda, Lesqx.—M. Kriocaulon porosum, sp. nov.—S. Cr. Aingiberites undulatus, sp. nov.—G. Rhizocaulon gracile, sp. nov.—B. B. Populus attenuata, Gvepp.—G., B. B.—Mo. (Gr. 3.) P. monodon, Lesqx.—Miss., P. mutabilis, A. Br.—B. ey, Miss. .. R., V.—Mo., (Gr. 2 and 3 in var.) P. balsamoides, Goepp.—P. ‘—Mo. , (Gr. 2.) P. leucophylla, U.—B. B.—Mo., (Gr. 2.) P. heliadum, U.— G.— Mo. Salix integra, A. Br.—G., B. B.—Mo. S. tabellaris, Lesqx.—Miss. S. (7) densinervis, Lesqx.—Miss. Myrica Torreyi, Lesqx.—B. B. ’ M. Torreyi, var. minor.—s. Cr. Betula gracilis, sp. nov.—G. SSG] PALEONTOLOGY—LIGNITIC FLORA, ETC. 381 Ulmus irregularis, Lesqx.—R., G. Celtis brevifolia, Lesqx.—Miss. Quercus angustiloba, A. Br.—G. . Moorii, Lesqx.—Miss. . platinervis, Lesqx.—V. | . Lyelii, Heer.—Miss.—Mo. . retracta, Lesqx.—Miss. _ chlorophylla, U.—G., Miss.—Mo., (Gr. 2.) . triangularis, Goepp.—G.—Mo. . Stramineus, Lesqx.—G. . Wyomingiana, Lesqx.—B. B. . furcinervis, Rossm.—Oregon, G.—Mo. -Goldianus, | sp. nov.—G. . Saffordi, Lesqx.—Miss. . crassinervis, U.—Tenn., V. 2. multinervis, Lesqx. aS . Benzoin, Lesqx.—Y. _ myrtifolia (2), W.—Miss. . attenuata, Goepp.—S. Cr. ° . Cleburni, sp. nov.—B. B. Fagus feronize, U.—G.—Mo., (Gr. 4.) Ficus Schimperi, Lesqx.—Miss. . cinnamomoides, Lesqx.—Miss. . tilizfolia, Al. Br.—P., B. B., S. Cr., G., &c.—Mo., (Gr. 2 and 3.) . planicostata, Lesqx. ae B. . planicostata, var. latifolia.—B. B., M. planicostata, var. Goldiana—G., S. Cr. Clintoni, Lesqx.—B. B. asarifolia, Ett.—G.—Mo. zizyphoides, sp. nov.—G. spectabilis, Lesqx.—G. auriculata, Lesqx.—G., (Gr. 2.) . truncata, sp. nov.—G. . corylifolia, Lesqx.—B. B. . ulmifolia, Lesqx.—R. FI’, Haydenii, Lesqx.—B. B. Platanus Raynoldsii, Ny.—B. B. P. Haydenii, Ny.—G., RB. P. rhomboidea, sp. nov.—G. P. Guillelme (?), Goepp.—B. B. (?), R.—Mo. ne 3.) Artocarpidium olmedizefolium, if. arcu —Mo Pisonia racemosa, sp. nov. mas B. Laurus pedata, Lesqx.—R., Miss. L. colombi, Heer.— VY. Persea lancifoia, Lesqx.—Miss. Benzoin antiquum, Heer.—B. B., G.—Mo. Cinnamomum Mississippiense, Lesqx. —Miss., B., P., G., M.. , (Gr.2 and 3.) C. Rossmeessleri, Heer.—G. —Mo., (Gr. 2.) CU. Heerii, Lesqx.—V. Bleagnus inzequalis, Lesqx.—Miss. Banksia helvetica, Heer.—Miss.—Mo. Andromeda Grayana, Heer.—R., V.—Mo., (Gr. 2., A. dubia, Lesqx.—Miss. A. vacciniefoliz afiinis.—Miss. Diospyros stenosepala, Heer.—Y. St. —Mo. D. brachysepala, Heer.—S. Cr., B. B.—Mo. D. lancifolia, Lesqx.—V., (Gr. 2.) See ee ee ee ee fe Vo Ele eh ade 382 GEOLOGICAL SURVEY OF THE TERRITORIES. D. anceps, Heer.—B. B. Sapotocites americanus, Lesqx.—Miss. Viburnum marginatum, Lesqx.—B. B. V. Wymperi, Heer.—B. B.—Mo. V. contortum, Lesqx.—B. B. V. Lakesii, sp. nov.—G. V. dichotomum, Lesqx.—B. B., R. Cornus incompleta, Lesqx.—M. C. Studeri, Heer.—G.—Mo., (Gr. 2.) C. Holmesii, sp. nov., S. Cr. ©. orbifera, Heer.—G.—Mo. Cissus levigata, Lesqx.—G. C. lobato-crenata, Lesqx.—B. B., (Gr. 2.) Vitis tricuspidata, Heer.—B. B.—Mo. Nelumbium tenuifolium, sp. nov.—S. Cr. N. Lakesianum, sp. nov.—G. Magnolia Hilgardiana, Lesqx.—R., Miss., (Gr. 2.) M. laurifolia, Lesqx.—Miss. M. Lesleyana, Lesqx.~—G., Miss., R. M. ovalis, Lesqx.—Miss. M. cordifolia Lesqx.—Miss. M. Inglefieldi, Heer.—B. B.—Mo., (Gr. 3.) Terminalia radobojensis, U.N—R.—Mo. Asimina (?) leiocarpa, Lesqx.—Miss. Eucalyptus Heringiana (?) Ett.—B. B.—Mo. McClintockia Lyaliii (?) Heer.—B.B.—Mo. Dombeiopsis trivialis, Lesqx.—G. D. occidentalis, Lesqx.—G. D. grandifolia (?), U.—G.—Mo. D. obtusa, Lesqx.—R. Acer (?) secreta, Lesqx.—R. Sapindus undulatus, Lesqx.—Miss. S. caudatus, Lesqx.—G., B. B. Aleurites eocenica, Lesqx.—B. B. Zizyphus distortus, sp. nov.—G. Paliurus zizyphoides, Lesqx.—B. B., M. Ceanothus fibrillosus, Lesqx.—G., B. B. Berchemia parvifolia, Lesqx.—G., R. — Rhamnus marginatus, Lesqx.—Miss. . obovatus, Lesqx.—G., R., M., (Gr. 2.) . deletus, Heer.—R.—Mo. Fischeri, Lesqx.—R. . Salicifolius, Lesqx.—M., G., B. B. rectinervis, Heer.—B. B., G., M.—Mo., (Gr. 2.) Dechenii, Web.—B. B.—Mo. acuminatifolius, W.—G.—Mo. Goldianus, Lesqx.—G. Goldianus, var. latior.—G. Cleburni, Lesqx.—G., B. B. discolor, Lesqx.—B. B. . inequalis, sp. nov.—G. . alaternoides Heer.—G.—Mo. . Meriani, Heer.—B. B.—Mo. Xanthoxylon dubium, Lesqx.—R. Juglans appressa, Lesqx.—Miss., (Gr. 2.) ' J. Saffordiana, Lesqx.—Miss. . i J. rugosa, Lesqx.—M., G., B. B., (Gr. 2 and 3.) ! HR RRA Ae Gee PALEONTOLOGY—LIGNITIC FLORA, ETC. 383 J. Smithsoniana, Lesqx.—R., G. J. Schimperi, Lesqx.—G., M., (Gr. 4.) J. rhamnoides, Lesqx.—G., B. B., (Gr. 2.) J. Baltica (?) Heer.—b. B.— Mo. Cercis eocenica, Lesqx.—M. Phyliites truncatus, Lesqx.—Miss. P. Manonieformis, Heer.—V. Carpolithes palmarum, Lesqx.—B. B., G., R., (Gr. 2.) C. faleatus, Lesqx.—B. B. . spiralis, Lesqx.—P. . compositus, Lesqx.—P. . Mexicanus, Lesqx.—P. Pielke! REMARKS ON THH SPECIES OF THE FIRST GROUP. In looking for the species which characterize essentially this group, ~ and may be considered as leading species of the Lower Lignitic, we have first to eliminate those which, as omnipresent Tertiary species, are about equally distributed in at least three stages of the Tertiary measures. They are considered as typical for the whole epoch, but cannot be taken as characteristic of any of its subdivisions, no more in this country than in Europe, where they have the same general distribution. Among them we count: Sequoia Langsdorfi, Phragmites Giningensis, Arundo Gepperti, Platanus Guillelme, Ficus tiefolia, Cinnamomum Scheuchzeri, Rhamnus rectinervis, Juglans rugosa and the closely allied Juglans acuminata. Cinnamomun Scheuchzert has not been yet discovered in the Lower Lignitic, but has been recently found in the Cretaceous strata of the Dakota group. Of the species as yet known only from American specimens, the ones more generally recognized at different localities of the Eocene Lignitic, are: All the fucoidal or marine remains of plants, especially Halimeniies major ; and in the other classes: Abie- tites dubius, most of the species of Sabal and Flabellaria, especially S. Campbellii, 8. Grayana; Caulinites sparganioides, Populus monodon, Myrica Torreyi, Quercus crassinervis, Ficus planicostata and its varieties, Ficus auriculata, Platanus Haydenti, P. Raynoldsi, Laurus pedata, Cinnamomum Mississippiense, Viburnum marginatum, V. dichotomum, Cissus lobato-crenata, Magnolia Hilgardiana, M. Lesleyana, Sapindus caudatus, Paliurus zizyphoides, Ceanothus fibrillosus, Rhamnus obovatus, Rh. salicifolius, R. Goldianus, R. Cleburni, Juglans Smithsoniana, and J. fthamnoides. To this list, already numerous, we have to add the European species of the Lower Tertiary, recognized in the same circum- stances as the former, Flabellaria latania, F. longirachis, Quercus chloro- phyla, Q. angustiloba, and those which have been already compared to Eocene species of Kurope, and found identical and closely allied to them. These, however, have a less extensive distribution than those mentioned above, not only considering the horizontal but also the vertical distribu- tion. None of them has been seen at a higher stage of the American Tertiary, while of the others, Halimenites major, Caulinites Spar- ganioides, Cinnamomum Mississippiense, Cissus lobato-crenata, Magnolia Hilgardiana, Rhamnus obovatus, ascend up to the second group. Even the four first species named above have representatives in the third division of the Tertiary. In considering the species of the whole list in regard to their vertical distribution, we find 25 species, or 13 per cent., represented in both groups 1 and 2; 11 species, or 6 per cent., ascend to group 3, and only 5, or 24 per cent., to the upper division. Of these, Pteris pen-: neformis, Fagus feronic, and Juglans Schimperit have not as yet been 384 GEOLOGICAL SURVEY OF THE TERRITORIES. found in the intermediate groups. Ihave placed in the table of the first group the species of fossil plants described from the Lower Mississippi Tertiary, in order to show their relation to species of the Western Lignitie, a relation which has been remarked already. For the same reason, the species of Vancouver, described from the specimens of Dr. Kivans, are placed in the table, indicating, with the flora of the lower group, a rela- tion as evident as that of the Mississippi flora by Sequoia Langsdorfi, one of the universal Tertiary species; Salisburia polymorpha, recognized at Spring Canon or of the second group; Sabal Grayana, of Mississippi; Populus mutabilis, Quercus crassinervis, described from Mississippi speci- mens in the Geological Report of Tennessee;* Quercus platinervis,t whose neryation is similar to that of Ficus planicostata. Laurus Colombi is described by Heer in his flora of Vancouver, together with Sequoid Langsdorfi, Andromeda Grayana, and Diospyros lancifolia. These two last species, however, are fromm Buzzard Inlet, and are probably refer- able to an upper stage of the Hocene, as they ascend to the second group in our Western Lignitic measures. The little known, therefore, of the Vancouver flora refers it to this lower stage of the Tertiary. LIST OF THE SPECIES OF THE SECOND GROUP. [Names of localities and abreviations: E., Evanston; Sp. C., Spring, Cafion, near Fort Ellis; Tr. Cr., Troublesome Creek; Mt. Br., Mount Brosse; E. Cr., Elk Creek; Y. 8. L., southern borders of Yellowstone Lake; B. B., Bellingham Bay; Mo., Miocene; Gr. Group. } Halymenites major, Lesqx.—E., (Gr. 1 and 3.) Gymnogramma Haydenii, Lesqx.—Sp. C., (Gr. 1.) Equisetum (!) limosum (?) Lesqx.—Y. 8. L. Abietites dubius, Lesqx.—Sp. C., (Gr. 1.) Abies setigera, Lesqx.—Sp. C. Salisburia polymorpha, Lesqx.—Sp. C., (Gr 1.) Phragmites Giningensis, A. Br.—H.—Mo., (Gr. 1, 3, 4.) P. Alaskana, Heer.—Sp. C.—Mo. Cyperites angustior, A. Br.—H. Cr.—Mo. Cyperus chavannesis, Heer—E.—Mo. Caulinites Sparganioides, Lesqx.—Sp. C., (Gr. 1.) Populus arctica, Heer.—E., Tr. Cr.—Mo., (Gr. 3.) P. mutabilis, var. lancifolia, H.i—Sp. C.—Mo., (Gr. 1 and 3.) P. mutabilis, var. repando-crenata, H.—E., Sp. C.—Mo., (Gr. 1 and 3.) P. balsamoides, Gp.—Y. S. L.—Mo., (Gr. 1.) P. leucophylla, U.—Sp. C.—Mo., (Gr. 1.) P. ovalis(?), Gp.—E.—Mo. P. Zaddachi, Heer.—Sp. C.-——Mo. Salix Groeenlandica, Heer.—Sp. C.—Mo. S. Evanstoniana, Lesqx.—H. S. angusta, A. Br.—Sp. C.—Mo., (Gr. 4.) S. Islandica, Lesqx.—B. B. Myrica ambigua, Lesqx.—Sp. C. Alnus Kefersteinii, Gp.—H., Sp. C.—Mo., (Gr. 3.) Planera dubia, Lesqx.—B. B. Betula caudata, Gp.—E.—Mo. - B. Stevensoni, Lesqx.—H., (Gr. 3.) Quercus platania, Heer.—Sp. C.—Mo., (Gr. 3.) Q. negundoides, Lesqx.—H. Q. drymeja, U.—E.—Mo. * Geology of Tennessee, by James M. Safford, (1869,) p. 427, Pl. K, Fig. 1. tNo specimens of this species are entire enough to show any part ofthe borders. LESQUEREUX.! Q. Gaudini, Lesqx.—B. B. Q. Ellisiana, Lesqx.—Sp. C. Q. Pealei, Lesqx.—Sp. C. Q. Godeti, Heer.—Sp. C.—Mo. Q. Laharpi, Gd.—Sp. C.—Mo. Q. chlorophylla, U.—Sp. C.—Mo., (Gr. 1.) Q. Evansii, Lesqx.—B. B. Corylus McQuarryi, Heer.—E., Sp. C._—Mo., (Gr. 3.) Fagus Deucalionis, U.—E.—Mo., (Gr. 3.) F. Antipofi, Heer.—H. Cr.—Mo., (Gr. 3.) Ficus tilizfolia, A. Br.—Sp. C., E.—Mo., (Gr. 1 and 3.) Ficus Gaudini, Lesqx.—E. F. auriculata, Lesqx.—Sp. C., (Gr. 1.) Morus affinis, Lesqx.—E. Platanus nobilis, Ny.—E. Cr., E. P. dubia, sp. nov.—Tr. Cr., Mt. Br. P. aceroides, U.—E., Sp. C.—Mo., (Gr. 3.) Laurus primigenia, U.—Sp. C. L. sessiliflora, sp. nov.—E. Persea Brossiana, sp. nov.—Mt. Br. Sassafras, species.—Sp. C. Cinnamomum Mississippiense, Lesqx.—H., (Gr. 1 and 3.) C. Scheuchzeri, Heer.—H., Sp. C.—Mo., (G. 4.) C. crassipes, Lesqx.—B. B. Cinnamomum Rossmessleri, Heer.—Sp. C.—Mo., (Gr. 1.) Andromeda Grayana, Heer.—HE., Sp. C.—Mo., (Gr. 1.) A. reticulata, Ett.—Sp. C. ; ; Persoonia oviformis, Lesqx.—B. B. Diospiros lancifolia, Lesqx.—E., B. B., (Gr. 1.) Fraxinus denticulata, Heer.—Sp. C.—Mo. Cornus impressa, sp. nov.—Mt. Br. C. Studeri, Heer.—E.—Mo., (Gr. 1.) Nyssa lanceolata, Lesqx. —Sp. C. Cissus lobato- crenata, Lesqx.—Mt. Br., (Gr. 1.) Vitis Olriki, Heer—E.—Mo. Liriodendron species.—Sp. C. Magnolia Hilgardiana, Lesqx.—E., (Gr. 1.) Acer trilobatum, A. Br.—H., Tr. Cr., B. B.—Mo., (Gr. 3.) Rhamnus obovatus, Lesqx. hy, (Gr. 1.) R. acuminatifolius, ‘Web.—Sp. 6.—Mo. R. rectinervis, Heer.—H., Sp. C., (Gr. 1.) Rhus deleta, Heer.—E. —Mo. R. Hiyansit, Lesqx.—E. R. bella (?), Heer.—Sp. C.—Mo. Juglans denticulata, Heer.—Sp. C.—Mo., (Gr. 3 and 4.) . appressa, Lesqx.—H., (Gr. 1.) . rugosa, Lesqx.—Sp. C., E., H. Cr., &e., (Gr. 1 and 3.) . obtusifolia, Heer.—E.—Mo. . rhamnoides, Lesqx.—H., (Gr. 1.) - Woodiana, Heer.—Buzzard Inlet. Carya antiquorum, Ny.—E. Cassia concinna, Heer.—E.—Mo. C. phaseolites U.—Sp. C.—Mo. Calycites hexaphylla, Lesqx.—FE. Carpolithes arachioides, Lesqx.—kE. C. palmarum, Lesqx.—E., (Gr. 1.) C. osseus, Lesqx.—HE. Cr. 2GS8S Cy Sy Cy Oy Oy PALEONTOLOGY—-LIGNITIC FLORA, ETC. 385 \ 386 GEOLOGICAL SURVEY OF THE TERRITORIES. REMARKS ON THE SPECIES OF THE SECOND GROUP. The flora of group No. 2 seems to be composed of species in pait identical with or closely allied to those of group No. 1, or with those of group No.3. The species of Spring Cation have, besides those which are represented in the whole Tertiary, Gymnogramma Haydenii, Abietites dubius, Salisburia polymorpha, Caulinites Sparganioides, Ficus auriculata, or five species considered as Eocene, type of the first group. The same locality has, however, of species represented in the third group, and > which are truly Miocene, Salix angusta, Alnus Kefersteinii, Quercus platania, Corylus McQuarryi, Platanus aceroides, and Juglans denticulata, or seven species. The floraof Evanston is mixed in the same way, for it has, in common with the first section, fruits of palms, (no leaves, however, have been found there as yet,) Magnolia Hilgardiana, Rhamnus obovatus, Juglans appressa, J. rhamnoides, or five species; and, with the third group, Populus arctica, Betula Stevensoni, Fagus Deucalionis, Platanus aceroides, Acer trilobatum. This intermixture of types might be explained in sup- posing that the specimens of Spring Cation were obtained from different localities ; but, as we have the same facies at Evanston, this supposition is groundless. Evanston has an enormous thickness of lignite deposits, separated in a number of beds of pure coal by clay partings, or thin intermediate layers of shale and sandstone. Four beds of lignite, meas- uring altogether 43 feet, are reported in a section of 99 feet*. the middle one, 32 feet thick, being cut by four clay partings. It seems, therefore, that there was at this locality, and perhaps also at Spring Canon, a pro- tracted formation of lignite beds, continuing, nearly without interrup- tion, from the Lower to the Upper Eocene. 1am inclined to consider this group No. 2 as Upper Eocene on account of the conglomerate beds by which it is overlaid. Its flora has, however, a marked character of its own by a number of species which as yet have not been seen out of it: Salix Evanstoniana, Myrica ambigua, Quercus negundoides, Y. Hllisi- ana, Y. Pealei, Ficus Gaudini, Morus affinis, Platanus dubius, Laurus ses- siliflorus, Calycites hexaphylla, Carpolithes arachioides, &c. All the Euro- pean species recognized in this group are Miocene. A number of its types, too, mostly found also in the third group, are northern types, arctic or Alaskanian: Phragmites Alaskana, Populus arctica, P. Zad- dachi, Salix Grenlandica, Quercus platania, Corylus McQuarryi, Fagus antipfi, Fraxinus denticulata, Vitis olrikt. Taking all together, one-half of this flora is a compound of arctic or of Kuropean Miocene species. LIST OF THE SPECIES OF THE THIRD GROUP. [Abbreviations for names of localities: C., Carbon; W. G., Wahsatch or Washakie group; M.B., Medicine Bow; R. C., Rock Creek; P. of R; Point of Rocks; Mo., Miocene; Gr., Group. } Sclerotium pustuliferum, Heer.—C. (?) Halymenites major, Lesqx.—C., (Gr. 1 and 2.) Taxodium, dubium, Heer.—C.—Mo., (Gr. 4.) Sequoia Heerii, Lesqx.—C. Equisetum Haydenii, Lesqx.—C., (Gr. 4.) Phragmites Giningensis, A. Br.—M. B.—Mo., (Gr. 1, 2, 4.) Cyperites, species.—P. of R. Smilax grandifolia, UW—C.—Mo., (Gr. 1.) Acorus brachystachys, Heer.—W. G., C.—Mo. Caulinites Sparganioides, Lesqx.—C., (Gr. 1, 2.) * Dr. A. C. Peale in Hayden’s Report, 1871, pp. 194, 195. eeuebrEEe | PALEONTOLOGY—LIGNITIC FLORA, ETC. 387 Liguidambar gracilis, Lesqx.—W. G. Populus arctica, Heer.—W. G., P. of R., M. B., C.—Mo., (Gr. 2.) . decipiens, Lesqx.—C. . attenuata, A. Br.—R. C., C.—Mo., (Gr. 1.) . equalis, Lesqx.—R. C. . nutabilis, var. repando-crenata, A. Br.—C.—Mo., (Gr. 1 and 2.) . latior, var. transversa, A. Br—W. G.—Mo. . latior, var. cordifolia, A. Br.—M. B.—Mo. Ajnus Kefersteinii, Gp.—C.—Mo., (Gr. 2.) Betula Stevensoni, Lesqx.—C., (Gr. 2.) Quercus platania, Heer.—C.—Mo., (Gr. 2.) «). Olafseni, Heer.—P. of R.—Mo. Q. zemulans, Lesqx.—W. G. Q. acrodon, Lesqx.—R. C., C. Q. Haydenii, Lesqx.—R. C. Corylus McQuarryi, Heer—C.—Mo., (Gr. 2.) C. grandifolia(?), Ny.—P. of R. Fagus antipofi, Heer—P. of R.—Mo., (Gr. 2.) Fagus Deucalionis, U.—C.—Mo., (Gr. 2.) Ficus tilizfolia, A. Br.—W. G.—Mo., (Gr. 1 and 2.) F. oblanceolata, Lesqx.—C. (?) F. lanceolata, Heer.—C.—Mo., (Gr. 4.) F. multinervis, Heer.—C.—Mo. F, arenacea, Lesqx.—C. F. Gaudini, Lesqx.—C. Platanus aceroides, U.—C., R. C.—Mo., (Gr. 2.) P. Guillelmz, Gp.—C., P. of R.—Mo. Coccoloba levigata, Lesqx.—C. Cinnamomum Mississippiense, Lesqx.—C., (Gr. 1 and 2.) Cinnamomum species.—C. Cornus rhamnifolia, Heer.—P. of R.—Mo. C. acuminata, Ny.—W. G.—Mo. Vitis Islandica(?), Heer.—P. of R.—Mo. Magnolia Inglefieldi, Heer.—W. G.—Mo., (Gr. 1.) Asimina miocenica, Lesqx.—C. Dombeyopsis equifolia, Gp.—P. of R.—Mo. Acer trilobatum, var. productum, Heer.—C.—Mo., (Gr. 2.) Paliurus Columbi, Heer.—W. G., C.—Mo. Zizyphus Meekii, Lesqx.—C. Z. hyperboreus, Heer.—C.—Mo. Rhamnus intermedius, Lesqx.—W. G. Rk. Goldianus, var. latior, Lesqx.—C., (Gr. 1.) Juglans acuminata, A. Br—W. G.—Mo., (Gr. 4.) J. rugosa, Lesqx.—C., W. G., P. of R., (Gr. 1 and 2.) J. denticulata, Heer.—C.—Mo., (Gr. 2 and 4.) Carpolithes cocculoides, Heer.—C.—Mo., (Gr. 2.) Po) Fg bg Pt et Fg) REMARKS ON THE SPECIES OF THE THIRD GROUP. The general character of the flora of the third group is positively Miocene. Its types are not mixed with older ones, and indicate for the localities where the specimens were found a higher stage of the Lig- nitic, which, however, appears to succeed the second group without any marked disturbances. ' According to the observations of Messrs. Meek and Hayden, the Washakie group is conformably superposed to the Black Butte or Bitter Creek series, without changes of lithological 388 GEOLOGICAL SURVEY OF THE TERRITORIES. characters, and there are still at Carbon and other localities a few rem- nants of the lower Lignitic flora: Halymenites major, Smilax grandifolia, Caulinites Sparganioides, Ficus tiliefolia, especially Cinnamomum Missis- sippiense, and a variety of Rhamnus Goldianus. But of the 56 species of the group, 31 are identified with species of the EKuropean Miocene, or of the Arctic flora. Of these last it has 13 species, or 23 per cent., four of them already counted in the Evanston division: Acorus brachystachys, Populus arctica, P. decipiens, Quercus platania, Q. Olafsent, Corylus Mce- Quarryi, Fagus antipofi, Vitis Islandica, Magnolia Inglefieldi, Paliurus Colombi, Zizyphus hyperboreus, Juglans denticulata, and Carpolithes coc- culoides. The Miocene facies of the flora of this division is equally well marked in species of its own or American species, like Hquisetum Hay- | denti, Betula Stevensoni, Ficus Gaudini, Coccoloba levigata, Asimina miocenica, Zizyphus Meekii, &e., all species evidently of more recent types than those of the two lower groups. The relation of this division with No. 2 is, however, indicated by 17 identical species, more than one-fourth of the whole number, while it is allied to the upper group only by a few of the omnipresent species, Taxodium dubvum, Prragmites Giningensis, Juglans acuminata, J. denticulata, and by only two species, Hquisetum Haydenti and Ficus lanceolata, not recognized in the lower groups. — The plants of all the localities referred to this division are of the same type. But the specimens labeled-Point of Rocks and Rock Creek have apparently been mixed, or indicate different localities than those which now bear these names. The Point of Rocks station is lower in the measures than Black Butte, and its flora should have the Kocene character, of course. But I could not find any remains of plants there or around in that barren country, though I spent two days in searching for them. The Rock Creek station is Cretaceous, and for miles around I found there nothing but representatives, in rocks and fossil animal remains, of the two upper groups of this formation, to fifteen miles farther west than Medicine Bow, where heavy sandstones of the Ter- tiary are covered by the lignite deposits of carbon. LIST OF THE SPECIES OF THE FOURTH GROUP. [Abbreviations for names of localities: B. Sp., Barrel’s Spring; Hy. F., Henry Fork; Gr. R., Green River; S. P., South Park; M. P., Middle Park; El., Elko; M. Cr., Muddy Creek; Mo., Miocene; Gr., Group. ] ; Hemitelites Torelli(?), Heer.—Gr. R. Pteris penneformis, Heer.—Hy. F.—Mo., (Gr. 1.) Blechnum Gepperti, Ett.—Hy. F. Aspidium Fischeri, Heer.—M. Cr.—Mo. Lygodium neuropteroides, Lesqx.—B. Sp. Ophioglossum Alleni, Lesqx.—S. P. Salvinia cyclophylla, sp. nov.—M. P. Lycopodium prominens, sp. nov.— El. Equisetum Haydenii, Lesqx.—B. Sp., (Gr. 3.) HK. Wyomingense, sp. nov.—Gr. R. Taxodium dubium, St.—EH].—Mo., (Gr. 3.) T. tijanorum, Heer.—B. Sp.—Mo. Glyptostrobus Europeus, Heer.—S. P.—Mo. Sequoia angustifolia, Lesqx.—El. S. Langsdorfi, A. Br.—S. P.—Mo., (Gr. 1.) S. Coutsiz(?), Heer.—M. P.—Mo. Thuya Garmani, Lesqx.—El. Thuites callitrina, U.—S. P.—Mo. pate en PALEONTOLOGY—LIGNITIC FLORA, ETC. 389 Pinus polaris, Heer.—S. P., E.—Mo. _ Pinus(!), species.—S. P. Abies Nevadensis, Lesqx.—El. Arundo Geepperti, Mu.—Gr. R—Mo., (Gr. 1.) Phragmites Giningensis, A. Br.—Hy. F., B. Sp., El.—Mo., (Gr. 1, 2, 3.) Juncus, species.—Gr. R. Poacites levis, H.—B. Sp., El.—Mo. Cyperus(!) Braunianus(?), Heer.—B. Sp.—Mo. Cyperites Deucalionis, Heer.—B. Sp.—Mo. Carex tertiaria, Heer.—Hy. F.—Mo. Sparganium, species.—B. Sp. Acorus(!), species.—S. P. Populus Richardsoni, Heer.—El.—Mo. Salix elongata, Web.—El.—Mo. S. angusta, A. Br.—Gr. R.—Mo., (Gr. 2.) S. media(?), A. Br.—Hl.—Mo. Myrica nigricans, Lesqx.—Gr. R. M. copiana, sp. nov.—S. P. M. acuminata, U.—M. P.—Mo. M. undulata, Heer.—El. M. latiloba, Heer.—M. P.—Mo. M. partita, sp. nov.— El. Comptonia Bronguarti(?), Ett.—El. Ulmus tenuinervis, sp. nov.—M. P. Planera longifolia, Lesqx.—S. P. Quereus semi-elliptica, Gp.—El.—Mo. Q. lonchitis, U.—Gr. R.—Mo. Q. Elkoana, sp. nov.—E]. Q. neriifolia, Heer.—S. P.—Mo. Fagus feroniz, U.—E].—Mo., (Gr. 1.) Ficus lanceolata, Heer.—S. P., M. P., Gr. R.—Mo., (Gr. 3.) Ficus Jynx, U.—E].—Mo. F. Ungeri, Lesqx.—G. R. F. populina, Heer.—G. R.—Mo. Cinnamomum Scheuchzeri, Heer.—Gr. R.—Mo., (Gr. 2.) Diospyros Copeana, sp. nov.—El. Fraxinus predicta, H.—M. P.—Mo. Ampelopsis tertiaria, Lesqx.—Gr. R. Weinmannia (?) roseefolia, sp. nov.—M. P. Eucalyptus americana, Lesqx.—Gr. R. Acer, species.—B. Sp. Sapindus angustifolius, sp. nov.—M. P. S. coriaceus, sp. nov.—El. Staphylea acuminata, sp. nov.—M. P. Ilex affinis, Lesqx.—Gr. R. I. stenophylla, U.—Gr. R., M. P.—Mo. I. subdénticulata, sp. nov.—M. P. I. undulata, sp. nov.—M. P.(?) Ceanothus cinnamomoides, Lesqx.—Gr. R. Paliurus Florisanti, sp. nov.—s. P. Rhus drymeja, sp. nov.—M. P. hk. Haydenii, sp. nov.—M. P. Juglans acuminata, Heer.—Gr. R.—Mo. (Gr. 3.) J. Schimperi, Lesqx.—Gr. R., (Gr. 1.) J. denticulata, Heer.—Gr. R.—Mo. (Gr. 2 and 3.) J. thermalis, Lesqx.—M. P. » 390 GEOLOGICAL SURVEY OF THE TERRITORIES. Pterocarya americana, sp. nov.—M. P. Carya Heerii(?), Ett.—Gr. R. Podogonium, fruit.—M. P. Podogonium, leaf.—S. P. Cesalpinia(?) linearifolia, sp. nov.—S. P. Acacia septentrionalis, sp. nov.—s. P. Leguminosites, fiuit and leaf.—El. Carpolithes et semina.—M. P. REMARKS ON THE SPECIES OF THE FOURTH GROUP. The fourth group is remarkably distinct from the lower ones by its peculiar facies. It has for characters of its flora a proportionally large number of ferns, 6 species, a Salvinia, a Lycopodium, 2 species of Hiquisetum, 11 species of conifers, and 9 species of Glumacee, viz: 30 species of acrogenous monocotyledonous and gymnospermous plants, or 37 per cent. of the whole number of species as yet known as its representatives. Moreover, the balance of the species is limited to few genera: to Salix, 3 species; Myrica and Comptonia, 7; Quer- cus, 5; Ilex, 4; Rhus, 2; Juglandee, 6. At first sight, this group appears scarcely referable to a Miocene flora, so different is its facies from that of any of the former divisions. It has, however, 32 of its species identical with species of the European Miocene, or a propor- tion of 40 per cent. ; while it is allied only to the lowest American group by 5 species, mostly of general distribution: Pteris penneformis, Phragmites Giningensis, Fagus feronice, Juglans Schimpert. With the second group it has in common the same Phragmites, Salix angusta, Cinnamomum Scheuchzert and Juglans denticulata ; and with the third Phragmites still, Equisetum Haydenii, Taxodium dubium, Ficus lanceo- lata, Juglans acuminata, and J. denticulata. It has thus preserved a remnant of the flora of the other groups, which, considered altogether, is very little; for the three first divisions have 267 species, and in elim- inating Phragmites Giningensis, represented in all the divisions of the Tertiary, we find only 11 species, or 5 per cent., of the flora of the Green River group represented in the others. If it had not so many typical representatives of the Miocene of Europe, and if at the same time it had some one of our living species, it might be considered as Pliocene. But of more recent types than those of the former groups, it has scarcely any; I can name only Ulmus tenuinervis, the fine Staphylea acuminata, and Ampelopsis tertiaria. The remains of plants at Green River are found in laminated shales with an abundance of skeletons of fishes. At Elko station, South and Middle Parks, the plant-bearing beds, com- posed of the same kind of thin, laminated, fragile, soft shale, have also preserved remains of fishes, insects, and fee.thers. The peculiar compound of the thin laminated slates of the formation, and the similarity of animal fossil remains, prove, as well as the gen- eral character of the flora, that the localities named in the above table are referable to the same group. Very few species, however, have been observed at more than one locality ; while, on the contrary, the species, most of them at least, are represented by a very large number of speci- mens. This fact, like the distribution of the species, indicates a vege- tation of high land, covered with lakes, swamps, and deep forests ot conifers, with a thick undergrowth of ferns and shrubs. With a vegetation of this kind, the number of species is limited, and these are generally circumscribed in local groups. A vegetation analogous to this, covered the northern half of Europe after the Drift period. In the Tertiary epoch it has its analogue with the Giningen or BER stage of the Miocene. resquersux.) PALEONTOLOGY—LIGNITIC FLORA—SPECIES. 391 § 3—DESCRIPTION OF SPECIES. I have described here only the forms which are considered as new species, with those, which though already known from Europe, had not yet been recognized from American specimens. Europe during the same period of time. There may have been, for ex- iasquereux.]) PALEONTOLOGY—LIGNITIC FLORA—SPECIES. 423 ample, at the epoch of the Lower Tertiary or Kocene, a higher tempera- ture, influenced by proximity to the sea, by its currents, by slanting areas exposed to the sun, &c., and of course a corresponding flora, Indo-Australian or tropical, &c., while, under different influence, we had at the same epoch a more moderate temperature and a flora with homol- ogous types, related to those appearing later in Europe, when the tem- perature was at a lower Gegree, in the upper Miocene epoch, for example. This explains, of course, the non-correlation of vegetable types at epochs which are recognized as synchronous by their animal fossils, and, therefore, contract our deductions of synchronism of strata, as indicated by identification of fossil remains, into more narrow limits. It is prob- ably for this reason that, in comparing the data furnished by our ancient floras with those of Europe, we have constantly recognized a kind of precedence of types which may be merely the expression or exposition of a difference of climatic circumstances at the same epochs. Of this, however, we have to learn a great deal more on those floras of old before we are able .to take any reliable conclusions, and for this reason, also, it is of importance to limit our deductions on what we may learn in considering our North American fossil floras. Paleontological data, animal and vegetable, have demonstrated, for the geological times, as far up as the Lower Tertiary, orat least the Upper Cretaceous, a uniformity of climate over the whole north hemisphere, from the pole to the equator, if not ever the whole world. The causes of this phenomenon are multiple and not yet satisfactorily explained. In the flora of the Dakota group, and also in that of the second and third groups of the Tertiary, this isothermal facies is remarkably proved by identity of genera with those of the flora of the north, or as far up as remains of fossil plants have been found, especially with that of Greenland. The Cretaceous flora of Come, described by Heer in his Arctic Flora, is represented only by species of ferns and conifers, which do not have any relation to the plants of the Dakota group, except per- haps by one single species, Sphenopteris Johnstrupi, which is compara- ble to Hymenophyllnm cretaceum. This flora of Come may be reter- able to a lower stage of the Cretaceous, as it has no remains of dicotyledonous leaves. In an upper floraof the same country, Profes- sor Heer finds mostly dicotyledonous leaves, and recognizes them as referable to many of the genera represented in our Dakota group. As the memoir of those plants is not yet published, itis not known how intimate the relation may be; but the generic identity is enough already to indicate analogous climatic circumstances in Greenland and North America at this Upper Cretaceous epoch. The flora of our Lower Lig- ~ nitic, the oldest of the American Tertiary, is as yet without rela- tion with any northern flora known untilnow. But that of the second group and of the third are related, as remarked above, with the Miocene Greenland flora by a number of species and typical forms, which are characteristic enough to show that a same climate influenced at this epoch the vegetation of both countries. Therefore, from this, it seems that as far up as the Miocene period the isothermal zone extended from the tropic to the pole, or that at that epoch the same climatic circum. stances have governed the vegetation of the North American continent. The relation of the floras to the climate being forcibly recognized in local differences, or analogies of vegetable forms, it suggests another question, that of the origin of the groups of vegetables characterizing either different stages of the Tertiary or different localities of the same epoch. Our flora of the Dakota group has for its essential representatives 424 _ GEOLOGICAL SURVEY OF THE TERRITORIES. (I consider dicotyledonous species only) leaves of a coarse coriaceous texture, mostly with entire borders. A character of the same kind is recognized in the flora of the Lower Lignitic group, which, like the former, has very few dicotyledonous leaves with serrate borders, a large propor- tion of coriaceous leaves, and also species of Viburnum with borders of leaves equally cut by short-pointed teeth turned outside, a same kind of dentation exactly which is remarked in a few dentate species of the Dakota group. In the European Cretaceous flora, as represented by Credneria, Httinghausenia, &c., of the Quadersandstein of Germany, the leaves have a facies, which, though different in some points, could be, however, compared with that of a few species of our Cretaceous ; for example, Httinghausenia Sternbergii, Stiehler, or Phyllites repandus, Sternpb., (figured in vol. ii, Tab. xxv, of Fl. der Vorwelt,) could be admitted as an original type of the multiple forms of Sassafras of the Dakota group. But when we look further and come to the floras of the lowest Tertiary of Europe, that of the lower Sezane for example, which, by the presence of Cretaceous and Tertiary types, seem to- indicate a flora of transition between these two formations, and is recognized as Lower Eocene, we find characters pointing out, I think, to a multiple kind of derivation. This Sezane flora has its: dicotyledonous types repre- sented by 21 genera, with 47 species, with more or less serrate or doubly-serrate and dentate leaves, and 11 genera, represented by 20 species, with entire-bordered leaves; therefore, a large predominance of leaves marked by acharacter mostly absent from the Dakota group and Lower Lignitic American floras. .Considering this Hocene flora of France only, with its species of Betula,2; Alnus, 3; Ulmus,2; Populus, 1; Salix, 3; Aralia, 6; Greviopsis, 5; Juglandites, 4; Celastrites,4, Rhamnus, 1; &e., all, even Salix, Juglandites, Rhamnus, with serrate leaves, it would be rational to suppose that the original types of the dicotyledonous flora did repre- sent essentially serrate leaves; while we had reason to admit a contrary conclusion from the characters of our Cretaceous and Lignitic floras, whose types, even from the same genera, Juglans, Salix, Populus, are represented by entire-leaved species. Also, in the dentate leaves of the North Amer- _ ican Cretaceous and Kocene, the type is distinct. With very few excep- tions, these have the peculiar dentation remarked in the description of Greviopsis Haydenti of Nebraska, and of Viburnun marginatum of Black Butte. Ihave compared this last species to V. gigantewm of Sezane, but only for the size of the leaves and the character of the nervation, not for the division of the borders, as seen above; for the Sezane species has long, turned-upward teeth, some of them doubly dentate, a character in accordance with most of the other kind of leaves of this European group. How to account for discrepancies of this kind? Is the Sezane flora rep- resentative of a formation absent from the American geology, or not yet recognized in it; of a land-formation which, under different climatic in- fluences, could have harbored the same types as the Sezane ones, intro- duced by some kind of agency? ‘This is evidently not the case, as the series of the Cretaceous strata from the Dakota group to the Lignitic is uninterrupted, and especially as both successive floras are related by a general character far different from that of the contemperaneous floras of Europe and of those of intermediate epochs. Now, admitting that the succession of generic types indicates continuous development or multipli- cation of forms and characters in ascending from the lowest strata of the geological formations, shall we say that a single form or type or species has been at different times the first and only representative of each group, though wide and multiple in its representatives it may be now? Or, con- sidering merely the dicotyledonous plants, which make their first appear- ie’ i Tesg tena] PALEONTOLOGY—LIGNITIC FLORA—SPECIES. 425 ance at the beginning of the Cretaceous, are they all derived from the modification of a same lower form, developed at the same or at different localities under influences of the same kind? I do not think it possible to suppose that the first leaf representative of a dicotyledonous has ap- peared only at one place of the surface of the earth, nor that it has been derived from a same organism over the whole world, nor that the ex- ternal first causes of modification have been the same. Therefore, even admitting the theory of successive transformation of vegetable types in a kind of ascending scale, it would be necessary to consider as multiple, local, varied in forms, the first dicotyledonous representatives. , If this is true for the dicotyledonous plants, it has to be equally admitted for plants of a lower type. Simple as they were, then, in their characters, they did hold, as seeds do, all the future typical conformations of their off- springs, resulting of influences of divers natures; but asit is the case with seeds of different kinds, the result of their multiplication of growth should, of course, have been represented by groups of vegetables of dif- ferent characters. This would account for the diversity of floras of the ‘same epoch at distant localities, or for the isolation and dissimilarity of types in the flora of two continents in synchronous formations. I believe, therefore, that the disaccord remarked in the floras of geological epochs, and which have been explained’by displacement of floras, or what is called a wandering of species, may be, in many cases at least, attributed to diversity of original forms. The more we descend toward the so-called primitive vegetable types, or the more simple have been the organism of plants, the more easily they should have been modified under local influences. A change of climate of 4 few degrees, which might have caused the disappearance or extinction of some species of plants, should have forced the deformation of others or the birth of new ones in a proportional degree. Though the intermediate links which connect ancestors and descendants in vegetable types are not always recogniza- ble, even in the oldest fossil floras, it is certain that all the groups have a general family-facies modified by some new and discordant forms of un- accountable origin. In our Lignitic, the group of Evanston, for example, ‘ introduces to the Tertiary flora the serrate leaves, its Carya, Alnus, Be- tula, &c. That of Carbon comes after with Acer, Ulmus, and other new types. Have they been brought up from Greenland, from Europe, or from another country, or have they appeared for the first time where we find them now? They must have had their birth at some place, anyhow ; and I do not see why this birthplace should not be accepted for the lo- calities where the types are recognized, rather than to suppose them born elsewhere and transported hereafter, adding to the problem a new proposition, which renders its solution still more difficult. As said above, the question is merely touched upon, as I do not wish to take ground either for or against the present system, now generally admitted, of the succession of species, or of their development by modification of form under any kind of influence. My purpose is merely to point out the importance of the study of our ancient North American floras, repre- sented by more homogeneous groups in a more regular succession, less diversified by geological disturbances, and which, therefore, may afford some more reliable data for consideration. The history of the vegeta- tion of the earth is in intimate relation to that of the human races, The proverb, “All flesh is grass,” is explainable in this way: that the vegetation of every epoch is in immediate relation to the synchronous beings ; that vegetable life comes first and that animal life is dependent from it; that therefore the history of the vegetation from its origin, or the vegetable paleontology, should not be left aside in considering, the successive phases of animal life in relation to the history of man. EE AR Elo d \ fe REPORT ON THE VERTEBRATE PALEONTOLOGY OF COLORADO. By Epwarp D. Corr, A. M. PHILADELPHIA, July 12, 1874. Str: I send herewith a report on the stratigraphical relations and vertebrate paleontology of the formations which represent the Creta- ceous, Eocene, Miocene, and Pliocene periods in Colorado, with a few species from other localities added. This essay is based on material collected by myself during a part of the summer and autumn of the year 1873, under the auspices of the geological survey of which you are director. This represents the following numbers of species from the respective formations, to which I have added the number from each which is believed to have been first introduced to the knowledge of paleontologists: Formation. Total. | New. 21 9 75 59 15 7 38 19 149 94 Hoping that the report will subserve the objects of the survey,. I remain, with respect, EDWARD D. COPE, Paleontologist. Dr. F. V. HAYDEN, Geologist in Charge, &e ¢ pees AS tis abla ' Va Ade Se Lae tt Fel a fea a) yw og bah ae i ul 1 i te Pe texters inty mits a ¢ ; o} CHAPTER I. INTRODUCTION. The water-shed between the South Platte River and Lodge Pole Creek is composed superficially of formations of the Pliocene epoch as defined by Hayden. The latter stream flows eastwardly through the southern parts of Wyoming and Nebraska, and empties into the South Platte near Julesburgh, Nebr. The territorial and state boundaries traverse this water-shed from west to east. The springs on its southern slope, which form the sources of the northern tributaries of the South Platte, issue from beneath the beds of the formation above named. At or near this point is an abrupt descent in the level of the country, which generally presents the character of a line of bluffs varying from two to nine hundred feet in height. This line forms the eastern border of the valley of Crow Creek until it bends to the eastward, when it extends in a nearly east and west direction for at least sixty miles.* Atvarious poiptsalong it, portions have become isolated through the action of erosion, forming ‘ buttes.” Two of these, at the head of Middle Pawnee Creek, are especially conspic- uous landmarks, torming truncate cones of about 900 feet in elevation, as Mr. Stevenson, of the survey, informs me. They are called the Paw- nee or sometimes the White Buttes; near them stand two others, the Castle and Court-House Buttes. The upper portion of this line of bluffs and buttes is composed of the Pliocene sandstone in alternating strata of harder ‘and softer consist- ence. It is usually of medium hardness, and such beds, where exposed on both the Lodge Pole and South Platte slopes of the water-shed, appear to be penetrated by innumerable tortuous, friable, siliceous rods and stem-like bodies. They resemble the roots of the vegetation of a Swamp, and such they may have been, as the stratum is frequently filled with remains of animals which have been buried while it was in a soft state. No better-preserved remains of plants were seen. The depth of the entire formation is not more than 75 feet, of which the softer beds are the lower, and vary in depth from 1 foot to 20. The superior strata are either sandstone conglomerate or a coarse sand, of varying thickness and alternating relations; the conglomerate contains white pebbles and ° rolled Pliocene mammalian remains. This formation rests on a stratum of white, friable, argillaceous rock of Miocene age, probably, of the White River epoch, as I believe, from the presence of the following species, which I detected in it: Hyanodon horridus, H. crucians, Oreodon culbertsonii, O. gracilis, Poebrotherium vil- sonii, Aceratherium occidentale, Hyracodon nebrascensis, Anchitheriwm bairdii, Palcolagus haydenti, Ischromys typus, Mus elegans, &c. The formation extends to a depth of several hundred feet, and rests on a stratum of a fine-grained, hard, argillaceous rock of a dark-brown color. Some of its strata are carbonaceous, and contain vegetable remains badly preserved; others are filled with immense numbers of fresh and brackish water shells, including oysters. I do not know the depth of this bed, but followed it to the southward until it disappeared beneath the Loess of the South Platte. The age of this formation is identical with that which underlies the fresh-water basins of Dakota and Wyo- ming according to Hayden, and concerning which difference of opinion * See Berthoud, Proceed. Acad. Nat. Sci. Phila., 1872, p. 48, where the bluffs are men- tioned. 430 GEOLOGICAL SURVEY OF THE TERRITORIES. exists among geologists. I, however, succeeded in procuring a number of fossil vertebrates from it, which not only prove conclusively its Me- sozoic age, but its horizontal identity with the reptile-bearing Fort Union beds of the Upper Missouri. This formation, which has been usually regarded as Tertiary, I determined to be Cretaceous in 1869, and the present discoveries establish that view as correct. The fossils which are described in the following pages represent Dinosauria of three spe- cies, a crocodile, and several tortoises, identical specifically with those obtained by Dr. Hayden on the Missouri, Big Horn Rivers, &e. Some of the shells I submitted to Mr. Conrad, and he pronounces them to be Cyrenas. South of the South Fork of the Platte, the Cretaceous beds have an extensive development, and south of the Kansas Pacific Railroad contain some beds of pretty good coal. The high tract of land which extends east from the Rocky Mountains, and constitutes the “ divide” between the waters of the Platte and Arkansas, is composed of Tertiary strata lying nearly horizontal. The head and distal end of the tibia, with six inches of the shaft, are preserved. The former relates with the end of the femur, resembling it both in size, simplicity of contour, and details of surface. The form is crescentoid, one horn being the cnemial crest, the other posterior and replaced by a short truncation. The inner (convex) face is rendered angular by a median tuberosity, and all round this margin shallow grooves cut the solid angle at irregular distances. The articular face displays the smooth area, and the shaft the delicate striz, seen in the femur. The distal end is unsymmetrieally lenticular in section, one side being more convex; the articular face is rugose, showing a fixed liga- mentous articulation for the astragalus. The convex face of the shaft is coarsely striate-grooved near the extremity; on the other side, the intervening ridges are represented by exostoses or rugosities. The flatter side becomes the more convex on the lower part of the shaft. corr.) PALEONTOLOGY—CRETACEOUS PERIOD—VERTEBRATA. 451 Measurements. M. Mransverseudiam eter. ol Ccondylesiobetemurca- =... ocs--ceesj2c5 cess cee ceceeeee .082 Transverse diameter of shaft of femur...-........- Bese sil ees ROA ete iS art a 053 § oimmrddlevoticondyles!zeasseraee tae oe ate eee ee nee 054 Diameter fore andvaft of side of condyles. 22/3222: . 0652222 s0<) Jesse loss) eee .069 : ) COUP ASTER Uo as cence mr es ST ERR 038 OTC BUCS ete ot apeie aka as cya ope oo ein ates Salle ainrs ied Cisenete mite 102 Diametenotmherdom tibia tore anGcalb= =o a emecss oe aston sce cee cote eee .096 GPANSVCLBCMS .a.c\e tos le se Cas blcitee othe roe a Se ee .060 2 heh 3 : PLANS VELSCME ei seh le dee ee ae eee .050 Diameter of shaft of tibia proximally } Jo TA PaRP ane. Mu 20 Dep, Ow Where 045 Diameter of distal end of tibia) tore and alte 000 IIIT, oo Remarks.—If the bones above described as pertaining to the hind limb are really such, they are smaller as compared with the dorsal ver- tebre than in Hadrosaurus foulket, and indicate an animal the size of a horse. POLYONAX, Cope. Char. gen.—A species considerably larger than the last, represented by vertebre and numerous fragments of limb-bones. The most characteristic of the former are two probably from the posterior dorsal region, which are somewhat distorted by pressure. The more anterior is shorter than the other, and exhibits both articular faces slightly concave, the one more so than the other. They are higher than wide, and the border is scol- loped above for the capitular articulation for the rib. There are numerous nutritious foramina, and some ligamentous pits on the articular surfaces. The inferior face is rounded. In the longer vertebra, both faces are more strongly concave, and at each end of the lower side there is an obtuse hypopophysial tuberosity. The sides of the centra of both vertebre are. concave. The neural canals are relatively small, and the neurapophyses co-ossified. A third vertebra without arches is similar in specific gravity, though without the white surface-layer of the others. It is appropriate in sizé and form to this species, and is peculiar in its flat form, resem- bling the anterior dorsals of the Hadrosaurus. In this respect it is related to the shorter vertebra of the two above described as the latter is to the longer. The surface of the posterior articular face is damaged; it was not concave, and is now slightly convex; the anterior is preserved, and is concave. POLYONAX MORTUARIUS, Cope. The articular faces are deeper than wide in the vertebre; the sides are smooth; the lower faces narrowed and probably keeled. Measurements. M. Armemon dorsal, length. of centrum. J222 sso 2). 8e be so ctcinfte athe sa diga eile vials ore 048 Anterior dorsal, elevation: to neural canal-.-..-.--.---..----------- Sitiatets 0. 0110 Menethvorpirstibrme; molar, 426 eee eee lee ee ele alac aie eee oe eee arpa . 0020 Elevationkoteirst true mi olabe2esesisee cae: ee alee seal eee eee eee ee . 0018 Depthiot ramus ati chirditrue molar yee eee eee eee eee ee cee eee eae 0027 HERPETOTHERIUM HUNTIIL, Cope, Synopsis, loc. cit., p. 5. The least species of the genus, represented by portions of three man- dibular rami with all of the molar teeth. All the cusps low, the median unequal, the anterior and posterior " divergent, the latter ‘concealed by the former when. in place, although well developed. Foramina below P. m. 2 and M. 1. MIOCENE PERIOD. 467 Measurements. M. Length of dental series, omitting canine and P.m.1 -.-.......-...-..-.-.---- 0. 0072 Mon cthOtsHEsubrue mM Olabet. cece sects snece sae cee 3 = eae inses 2s stain see sets nee . 0013 TEAS 7 (BDaeL LD sR HULETS) FET GIA gg eye PR A DU eG . 0010 Length of third true molar ..--......-- sdomeqyseemotioe Hino oEB EAE Ewe Sekine . 0013 Wepthoteramas ab ibirdstrae molar 552 s6).- ss os5 ode elshcee fees Modes . 0019 Dedicated to my friend Prof. T. Sterry Hunt, of Boston. HERPETOTHERIUM STEVENSONII, Cope, Synopsis, loc. cit., p. 6. A very small species. Median cusps of molars unequal; the exter- nal much elevated, and separated by a deep notch from the anterior. Heel of M. 4 contracted. ~ Measurements. M. Men eihotelast bw! MOIS ~serstmaeeses fesse sneha ala dhe see Ce aelcee decsee 0. 0029 ene thvor third’ irove;molancree cess 12 oes eels Boe HOBGod meee SAdaeas UsSar . 0015 Bievebion. of thirdsinwe! Molans ek Sse o's eh haere Aa es doe nsee cs 2 . 0012 Depibiok ramusat third) true molar. 2p. sila aie a sno) Sie ses lone Dacecanebie oe 0020 Abundant. Dedicated to my friend James Stevenson, of the United States Geological Survey, the discoverer of the deposit from which the fossils here described were procured. HERPETOTHERIUM FUGAX, Cope, Paleontological Bulletin, No. 16, p. 1; Synopsis New Vert. Colorado, p. 6. Gianiith wide ; interorbital region flat ; muzzle narrowed, but still wide and plane above. Mandibular rami long and slender; mental foramina below the first premolar and the first molar. The foramen infraorbitale anterius is situated above the third: premolar. There is ashort diastema behind the first premolar in both jaws. There are rudimental basal tubercles fore and aft on the second superior premolar. The superior canine issues a short distance behind the maxillo-premaxillary suture. In the inferior molars, all of the five cusps are distinct to the base, except the median pair, which are connected by a deeply-notched yoke. Enamel smooth; no cingula. The nasal bones are expanded behind and their posterior suture is medially emarginate. . Measurements. : M. Wadihoterantumatiront iorbit=.sses-eseans os scess ase eee eure ete ee eee 0. 0160 Width of muzzle at canines - aeais sae sista tars eer Be 0050 Length of bases of crowns of ‘four true molars of upper Jay BPC had geet . 0070 WensuimotspAasesol tive IMterlOM MOlALS.aseea)-- sacs |e oe eee ne sence. OLOO Length Ombasigotcrowl ot lash-molar co. 2oie. 5 - A.Hoen & Co. lith. Baltimore SYMIBORODON IBUCCO COME. i eis aise ah ie UWS. bealagtcal Sievey of the Cervitaries . IPILLY. A.Hoen & Co. lith Baltimore SYMDBOROD ON ALDOR OST CO A.Hoen & Co lith. Baltimore SYMIBOROIDON AILTOUROSTIRIS COPE. he us eweeier: ix ig a aa a rou] . PL VA. WS. Sealogical Surwey af the Cerritories . aromureg “Yt 0D 9 WOH y AOD UAV NOCOWOAINAS a TrTUrws . atthe Ge > WS, Geological Survey: A.Hoen & Co lith. Baltimore SYMUBORODON IBUCCO. TIRIS . 2, 4 SYMBORODON ALTURO 3. SYMBORODON ACER. Pegg eee ore S nn sen PALEONTOLOGY—MIOCENE PERIOD. A85 It is probable that both sexes of these species are horned. This is the case with all of the crania which I obtained in which the nasal region is not wanting, and doubtless many of these are females: The only one which I obtained with reduced horns is one of the largest size, (S. helo- ceras,) and does not probably represent the only female of the collection. The general appearance of these species when living must have com- bined features of the rhinoceros and elephant in almost equal propor- tions. The length of the femur indicates that the first joint of the leg was free from the abdominal integument, and that some of the species stood higher on the legs than the rhinoceros. There is indication of a trunk, probably a short one, since the neck is not so remarkably shortened as to render this organ absolutely neces- sary. The indications are: the massive borders of the nasal meatus separated laterally from the face by a vertical, obtuse angle; the great stoutness and shortness of the free end of the nasals, which much resemble the same region in the elephant; and the reduction of the pre- maxillary region and its teeth. It is altogether prebable that it had no great length, resembling, perhaps, that of the tapir. These views are in accordance with those already expressed by Professor Marsh in his description of Brontotherium ingens.* Professor Leidy had previously inferred a short proboscis for the Megaceratops coloradoenesis. As com pared with the Hobasileide of the Eocene, their appearance must have been lessexceptional. The proboscidian foot, with short neck, reproduced the elephant; while the narrow head, with the posteriorly placed horns, and the very elongate muzzle, gave these a more suilline expression than the symborodons. The powerful horns, admirably situated for effective use, did not avail to secure their survival beyond the Miocene period more surely than did the laniary tusks of the Hobasileide in conquering for them a place in the ages that succeeded the Eocene. As the most powerful of the Ungulata ot the Miocene, they were the legiti- mate successors of the Hobasileide, of the Eocene, as these were of the great land-saurians of the Cretaceous. A few mastodons and elephants contested with them the supremacy of the Miocene, anil held it without rivals in the Pliocene; but why the less formidable rhinoceros should have continued with them, while the Symborodons dis- appeared, is a problem whose solution cannot yet be conceived. The material on which the above determinations and deductions are based is abundant. The expedition obtained portions of fifty individuals, probably referable to this genus, and twenty-five complete or fragment- ary crania. ‘Those certainly determined belong to the species in the following proportion: S. bucco, 3; S. torvus, 2; S. altirostris, 2; S. acer, 3; S. heloceras,1; S. trigonoceras, 6; S.ophryas,1. Crania of S. bucco and S. acer were obtained with mandibles associated; the other species were not; nevertheless, it is probable that some of the various mandibles found separately pertain to the most abundant, S. trigonoceras. SYMBORODON BUCCO, Cope, Synop. New Vert. Col., 1873, 10. The largest species of the genus approaching nearly the living ele- phant in size. Represented by an imperfect cranium; by a cranium almost perfect, including, very probably, both mandibular rami, with entire dentition; a fragmentary skeleton, including parts of cranium, teeth, and vertebrae. The crania are very depressed in form, and exhibit a peculiarity in the horizontal expansion of the malar bones, and the still greater enlargement of the zygomatic processes of the squamosal. *Amer. Journ, Sci. Arts, 1874, p. 486 GEOLUGICAL SURVEY OF THE TERRITORIES. These form two horizontal bony masses of remarkable size, with the ex- terior botder convex in both the vertical and horizontal planes. The hasal bones are flat and truncate wedge-shaped. The horns are sit- uated above the face in front of the orbit, and are expanded in one plane, so as to be much flattened. Their length is moderate, and their direction outward and forward. There are slight angulations of the frontal and zygomatic margins, which form slight contractions of the zygomatic orbital fossa, one behind the orbit, the other marking the an- terior four-tenths of the zygomatic fossa. The orbits are small and hor- izoutally oval, and the temporal fossee contracted. The latter are greatly extended posteriorly, and are bounded by an ear-shaped prolon- gation of the exterior occipital angular ridge to beyond the line of the foramen magnum. The plane of the vertex and front is wide and unin- terrupted by tuberosities, but forms a gently concave continuum. The dentition is 2, 1,4, 3. The anterior teeth are all small, the posterior large. There is no internal cingulum on the molars, which are smooth and with Jow internal cones. Measurements. M. Menervoheraninm: (Garin ches)s eer ece eo eae eee eee eee eee eeecees 0.840 Width of cranium, (25 KG] OKs) en 8 EES Tae Ee eu Mine Ae eR Be aA Se ri 636 ‘Length of nasal bones to bases of horns...-..- Poa eee Soerscwris waco Heemeee L07 Wen othyoi@onbibess see ase s ee cee eats ENA SON na Pa NIRS le poe eS TUE I 115 VARLERVOL macaloa sl) (02 ley Mats J he ber oc Tn eto iaae 152 Width) abovierarbitsicc sate sae aemoe ce ve seinessy J oaier ae one a eae eee eee 255 Width, least, between temporal fosse...--...--------2------5+-oe-- eee oe 170 Width of mass of zygomatic squamosal.......--....-.-...-2..--..----- ----- 140 Width between temporal fosse behind.............--...--2.------+--------- ol This large quadruped was considerably larger than the S. acer, Cope; but the horns are shorter, and of an entirely different form. Its orbits are remarkably small, and during life the eyes were directed more or less obliquely upward. The broad, flat, wedge-shaped head is not unlike that of snapping-tortoise (Chelydra) in its physiognomy. IT append here a description of the mandible, on which the species Symborodon torvus was established. I am not able at present to refer it to its proper cranium, but hope soon to have that opportunity. It nearly resembles that of Symborodon bucco. Wentition; L., (?) 0; C., 1; P. m., 3; M., 3; the canines slightly separated from each other, but not from the first premolar; crowns of the premolars with L-shaped crescents, asin Khinocerus ; of the molars with completed crescents; the last molar with third posterior crescent; symphysis mandibuli co-ossified ; crowns of canines not projecting, conic. Symphysis oblique; ramus rather shallow. Last molar with three columnar ribs on the outer side, four om the inner, produced by the continuance inward of the ridges from the anterior and posterior outer cusps. Hnamel nearly smooth; a cingulum round inner basis of crown of canine. Measurements. M. Length of mandibular ramus. .....----- Site mnta sea ciaernaees Sea paneeeoosous -- 0.520 Men othr of sy map lysis recess eet EN A eee a cea Seer e cyte eres aa 144 Wenpthi Ofserles Ok ANOVATS) 04 asl alee ole a apne eee re are e 320) Wenothvorseriesrotorie nol ars ase sseee oe coe eee Eee eee eer er ec reo 215 Benethotlast molar se sik ae ee ace tas er eh oo cy ee eer 038 en Sthvot penultimate molares-se eee eee eee eee eee ee ee eee ene eee 072 SYMBORODON ALTIROSTRIS, Cope, Synop. New Vert. Col., 1873, 12. A large species represented especially by a nearly perfect cranium, cone PALEONTOLOGY—MIOCENE PERIOD. A87 and probably by several others, some of which are nearly perfect. The muzzle is shorter than in any other, and the orbit wore anterior. The premaxillary and nasal bones are shortened; the latter broad, obtuse, and massive, aud standing on a plane above that of the front. The ver- tex and front do not form a continuous concavity, as in other species, but are divided equally by a tuberosity on each side; posterior to these the vertex is flat and rather wide, while the front anterior to them is roof-shaped. The temporal fosse do not project so far behind the ocei- pital union as in some species, and the squamosal bone is not remarkably expanded laterally. There is a small postorbital angle. The front rises much to the basis of the horns. Each of these stands above the orbit and face at the base, and one-third of each over orbit; face and nasal bones above the latter. They are straight, with approximated bases, and but moderately divergent. They are subcylindrical at base, and compressed inward and forward at the narrow apex. The maxillary rises on the base, forming a squamosal suture on the anterior and lat- eral aspect, opposite the nasal meatus, and below the nasal bones. The first premolar and two incisors are very insiguificaut ; canines with short, stout crown. The premolars have no inner cingulum, but two smooth cones. The molars have only two inner cones, which converge toward the crescents. The latter do not give origin to any transverse crests. Measurements. M. Monethiof cranium, (252 1nches))|ssminscc)eciseis seen eee cieos coe osenarseee se 0.649 Mens thvof crowns Ou peeum irOnWeaANINe ee an ease see eee eee ne se cee 444 Hono iin Oh ie MOIMES se afjosee cine. abe eau teehee Se Ne SHE CORE I .240 Weng ohvotlast Moana: cocsecsthaaws ght ose sR Se esi eee ee Shae is stcan BS 083 Wrdihkotelastmolanea: jcc ccrcsm oc. aici seyaners os sasisiervace cree sereeMeeaase seca 054 Wadthiotnrstcpremolaresser ca sccm sae ee eo br crcte einem eles es Se ane 035 Hen PUNO teHinsouPLEMOlAT seta aecloneiachace ees cs cee atic neta out oe Ane meses .026 Wer Sih ton Ditka ay eye te arts eit ovale seonnsuiies Woah ee weciesaumls eaeenins .090 Measiawidtheot parietal planer sae a e25\Seleclcia ancien cc ee cee hacia svt eee asec 230 Menethvof nasalstromvhorms.2 22 --=- 5-05 sees sec eee Eafe vcore ay ce cere te 045 Wacthvotmasalsrat, Norms: (ooo em bein cists ama clei e cise clays Sajal ein: temic aieeiciee 152 Boneh OtnOEn-COre: ApOVEOLDIty (GINCHES)).0<.. oon = oe cits nis cites Sees cles 229 ensthyor horn-coreiabovemasal DONS) 2255-4 ss2 seelo= ool enls~ se ee oe se eee cee 140 This is one of the most formidably-armed species, and must have pre- sented a most outré appearance in life, owing to the extreme shortness and elevation of the muzzle and anterior position of the orbit. The general form of the cranium reminds oue of a pack-saddle without the hind cross-trees. . I owe the discovery of the beautiful cranium, which represents the species, to the acuteness of my assistant, William G. Shedd. SYMBORODON HELOCERAS, Cope, Proceed. Amer. Assoc. Adv. Sci., 1873, 109; Synop. New Vert. Col., 1873, p.14. Megaceratops heloceras, Cope, Pal. Bull. No. 15, p. 4. Free portion of nasal bones as broad as long. Horn-cores mere tuber- osities, with one flat outer, and one very convex, face presenting in the other directions; summit contracted, truncate, oval in outline. See eee aesee Ae ee eeeee 082 Length of molars and last three premolars ---....-..-.----.------------------ 2293 Mensthiomashthreespremolarseecere mee see eee eee oe eee eee eee eee 110 Menevhy from =nasalinieabus| bo OLD Ib see ee see eee ee le seine Seen lee eae eee 103 enethiok crown ot second premolarsessssisos2. sees a2 See eee nese MRE el 029 Widithyotjerown) of Second premolarsecsee es ee eee ee ee ae eee eee os eceaeee ees .038 Height of crown of canine. -..-..----..----------. DONS a aia Sa AO ta, ln (a Ue aaa Diameterion crown at bases. sss see eee orice sees oat ee aac eeee aoe oer eee EP Depth of frontal tuberosity ...--...-..--.-------2 ---- <2 NEVER SRE EP Suir es Iie oe 038 Midmeterofmnrontaly tuberosity. -aaeae see ceeolesiee oo ee eee ee eee eee Od Diameter of horn-core, transverse... ...-.. .--- -- -2 02 ee ee ee ne we ee eee eee eee 038 Diameter of -horn-core, longitudinal..........-.......--.------.--.--------e--6 O49 Although the specimen from which this species is deseribed is as large as the smaller of the S. trigonoceras, it does not belong to an old animal, as the cranial sutures are distinct. It makes one more addition to our knowledge of these curious forms, whose abundance during the Miocene cone PALEONTOLOGY—MIOCENE PERIOD. 493 period reminds one of the antelopes of the present period in Africa. It is so distinct from the typical species of Symborodon as to render it not unlikely that it will be proper to call it Miobasileus hypoceras. HYRACODON, Leidy. HYRACODON NEBRASCENSIS, Leidy, Ext. Fauna Dak. and Neb. ., PD. 232, Abundant in Colorado as in Dakota. During maturity, the first infe- rior premolar is Shed, while that of the upper jaw is retained, leaving the formula 3, 4. HYRACODON ARCIDENS, Cope, Paleont. Bull., No. 15, 2 HKstablished primarily on a specimen which includes the left maxillary and premaxillary bones with the teeth as far posteriorly as the fifth molar. Some of these were not fully protruded, and the third premolar of the deciduous dentition was attached, the removal of which displayed the crown of the permanent tooth. The species is about the size of the HI, nebrascensis, and differs in the form of the inner lobes of the molars and of the first premolar. All the molars have the outer longitudinal and inner transverse crests, the posterior short, the anterior much curved backward round it, and thus forming the inner boundary of the tooth-wall. The first premolar is shorter than the others, and has a short anterior lobe. The milk-molars show more nearly transverse crests as in Ahinocerus, but the first premolar had the anterior lobe. Canine and first incisor short, conic ; second incisor with an outer lobe; median incisor transverse ; enamel smooth. Measurements. M. BensrnomourismpeLor MoOlars Vatese se -ealcw eee es. sees anes eke cme 0.072 enol mot OiASGMIAl.) a2 mise siaete mw cetetalei a eves A- s2ahho aap ISae Scere ane S toes .006 Menai womcaninevands iINCISOLS seems ee moraisesseicicas Secisce = sels tee en se eee eieetas .020 Meow UNO HefUESb) PLOMOl A = ote acess see ices stots yc ela) ae cemnaiare Bens oataveialee oe cio aeae) 014 Wrdihtoiiminst premolar ieee te eau oe hie eee aac aso catiee cow meats ccm e Sas 012 Mens uo ibindupremolar twa sele wes exe chars ae rete ete yee al lie seielcres & Serie terns 021 Wadthvot thirds premolarasse: ses oscseuees Se sekelseieisae Sates ones cose nseeran manOee eiaht ot CHieG: premOlabe tease Sue ie baie se blak yes amino cae mete eee mam Ce ei ee mete .025 ACERATHERIUM, Kaup. At least three species of this genus have left remains in the White River beds of Colorado, for the third, which I formerly referred to the preceding genus, may find a more appropriate place here. They are distinguished as follows : I. Crowns of premolars 2-3-4 broader than long: Smaller: symphysis mandibuli much shortened and contracted.— A. mite. Larger: symphysis elongate, with large incisors.—A. occidentale. Il. Crowns of premolars 2-3 as long as or longer than wide: Size of A. occidentale ; P. m., 2, subcuneiform. —A. quadriplicatum. ACERATHERIUM MITE, Cope. This species is intermediate between the A. occidentale and Hyracodon nebrascensis, not only in size, but in its short concave diastema, and short, contracted symphyseal region. There are two large external incisors, which are not only absolutely but relatively much smaller 494 - GEOLOGICAL SURVEY OF THE TERRITORIES. than in the A. occidentale. If any median incisors exist, they must be small, as the narrow fracture-surface below the original alveolar border exhibits no trace of alveoli. The mandibular teeth are rather elongate, the first having two roots. The ramus has not the incurvature to the diastema seen in H. nebrascensis, and is relatively not so deep, and more robust below the last molar than in that species. Associated with this mandibular ramus, I found the large part of the skeleton of the same animal and the superior molar dentition of two individuals of the same size. The teeth resemble those of the A. occi- dentale, but, besides the smaller size, exhibit differences in the structure of the premolars. The first is about as broad as long; has a strong anterior basal cingulum, and both of the transverse crests strongly curved backward at their inner extremities. The second is transverse, and the transverse crests are simple and distinct distally. The third premolar has its inner anterior angle produced at the base of the crown. The transverse crests form a continuous circuit inwardly, and it is the posterior which-curves forward and joins the anterior a short distance external to the inner termination of the latter. In the fourth premolar, the transverse crests are entirely distinct, and the anterior is the longer, causing, as in the third, the protuberance of the inner anterior angle of the shoulder of the crown. Both are bounded at the base by a cingu- lum, which extends round the posterior base to the outer crest. The posterior transverse crest sends forward a process toward (in one speci- men joining) the anterior at one-third the length from its end. The transverse crests of the true molars are simple, and the anterior cross- crest the thickest ; no cingula on the inner bases. Measurements. henoth of inferior molarseriesetac.o.ee ee ease Meee oeienee seca) ssee ce oeeeeeee 0.172 henge thiof premolarstomly as cccrse =e eee ee ose tse cia eaten erage ee ee .080 Wengthoffirstpremolary cnc see ences ocak lee cnr s eaione a ele eee eae 015 Length from first premolar to end of symphysis. -...----.-.------------------- 040 eneth of symphysis soe ce en ciel ciel ee scars eis eas ie ee eee oe ee 048 Waidithvorisyiphysisiatidiastemar =s=oes tae cists se aceeeee ee eee eee eee eee ee .040 Depth ofiramusiat astm ola Ge ys SMa ee SE Na ERE ye ee aoa a eee .050 nielkness Ot mannMs iy les WHOS cosas cadcos obo odaoas UoooUaSegs cooaGb Seno se 030 Diameteriof imieriorineisoke= seo ser eee eee eae ace a rae eee .010 Heneth) ol seriesioG superior molats | eee e tae ete eee ae eee eee 153 Length Olsenlesiot superior premolars seas sae see eae seee ences ee eee eae 073 Leneth of firstypremolar: As Vieeo sess Nees ae Ra Ode Shee Met eo are Olle Lengt hoftourbh prem olatsese sieves sete cle see seattle ste a een ee eee eee 022 Width of fourth PLCMOL AT eee RN aa IN eee aa ey cte oe - 032 ens thvor penulinnatormolance see. ree ee sae Sees en eere heer eee eerie 037 Width-of-penultimate: molar:.... 055.2. 42 J 220 So a Sen as a a et The other series of molars presents similar dimensions, and a few slight variations in structure. The remainder of the skeleton pertains to one or the other of these individuals. The axis strongly keeled below; the anterior articular surfaces are widely expanded, and the posterior is coneave and oblique. Its neural carina is elongate and elevated behind. The dorsal and lumbar vertebre are slightly opisthocelian. The glenoid cavity of the scapula is a broad oval, and the coracoid is quite prominent, but obtuse. The internal condylar tuberosity i is strong, the external almost wanting 5 the internal distal crest is very strong. The supracondylar fosse are very deep. The radius is a stout bone, and attached to the slender ulna by coarse sutural surface, which is very narrow along the middle of the shaft. The femur is stout, and its large trochanter’ is recurved anteriorly as well as posteriorly so that both faces are concave. There aos PALEONTOLOGY—MIOCENE PERIOD. A95 is an elongate crest in place of the little trochanter. The trochlear groove is angular, and bounds a pit just above its proximal end; the condyles are subequal. The crest of the tibia is deeply grooved, and the spine divided by a wide gutter. The external face is concave proximally, and turns to the front distally. The inner proximal face unites on the last third of the length, to become the internal face. The distal posterior face narrows upward, and runs out below the inner facet of the head. The astrag- alus has the hour-glass face quite open. The inner tuberosity of the head extends within the line of the trochlea a half-inch. The cuboid facet is oblique and parallel to the outer margin of the head, and con- stitutes one-fourth the width of the latter. Measurements. M. LPG A GH madhhsloS-e-6 ceedadbsces5 Clee scede sae saceiacinn coonUS Sa eae GOO ROO ES 0.198 DAME LOMO tS CaTpal fac Orcs atria ee ae sees lone ela oes rataia aioe ea nis a mere 041 Mirdbhrofthumerus distally 0s san ssa ahtee se weeee oem at oo See eae 058 Depihof outericondylejof humerus, distally .2 025222523502 Set ek ee eee .048 Lone diameter of slenoid face of scapula -..---. ---.-:----+----2+se-40-------- 042 Short diameter of slenoid face of scapula --.....---.------ ---------- eeee-e-=- .038 Meneuhvoteremur: (OVer alll) sseicnce sie ose usateaaeisie cece ra vise ma celo smelae sas 295 Proximal width of HOMILY (OVOE TAIN) Mostra ter tee Met en lant a ale Wen Ate oie cetare ate .100 Diameter of head, (antero-posterior) SSG STE Resa kk Bie te BUS A de ak bea) .042 Least transverse diameter of shaft _.....-...---+s-ss+cesce+sseceseeeee Sageletiee 035 Hransverse.diatheter/ Or condyles) = s-c25. css. cece Seieine cece core seen sneeatec ee 060 Antero-posterior diameter at condyles......---...----.--.-- Lroep oats s) epoteewae 084 STO MALO HUI la se eee ce NN Pees RT MSR EES UND EE AE Ee 230 Diemiever Of head, janbero-posbenOn essences aaa esis eee ae a eee 580 Diameter of head distally, antero-posterior -..--..----.----------------------- .036 Wiameter-or head distally, transverses s. -s-1sc e-sees sac scence oo ece ee esas ea OG0 Diameter of head of astragalus, transverse ....---.-.-- 20. 02-220 ence ee nee 048 This rhinoceros was about the size of a mule. ACERATHERIUM OCCIDENTALE, Leidy, Ext. Fauna Dak. and Neb., p. 228, Plate xxii. Several specimens from different localities. ACERATHERIUM QUADRIPLICATUM, Cope, Hyracodon quadriplicatus. Cope, Pal. Bull, No. 15, p. 1. This species is similar to the last in bulk, with greater proportional elongation of the teeth of the premolar series, at least. It 4s repre- sented by two individuals, one possessing the permanent, the other the temporary dentition, at least i in part. The former presents only the second and third premolar teeth with an alveolus of the first. The third premolar has four roots and strong basal cingula fore and aft only. The transverse crests are simple and separate. A strong but short crest originates from the outer marginal crest between them, and being in near proximity to the anterior and trans- verse, it nearly isolates a triangular valley with it. There is alow tubercle between the bases of the inner extremities of the transverse crests. The second premolar is three-rooted only, and is narrowed ante- riorly. Its two inner cross-crests are widely separated, and the inter- vening branch is rudimental. The anterior prolongation of the external crest is longer than the posterior. The second specimen consists of molars in both maxillary bones, viz: the four premolars, probably deciduous. They differ in appearance "from those above described, but not in essential details. The transverse crests are little curved, and the outer elevated crest A96 GEOLOGICAL SURVEY OF THE TERRITORIES. uninterrupted. A short elevated fold proceeds from the latter, dividing the head of the transverse valley. A compressed conic tubercle stands between the inner extremities of the crests. The first premolar has two transverse crests and an anterior tubercle. The posterior crest is strongly curved backward at its inner end. A strong cingulum sur- rounds the base of the crown except on the outer side. Measurements. M. Lengthiofschree antertornnolars) ys sscs\oscilseet seine e eacisee seinisiciniee el aseeiaane 0.090 Lenethior third)molar= 2s... 2 242.) 22. sl eo scccl= uadoad WEES RSE One anG coos .030 Widthrofithirdimolare eee. oe Ce cee etcicae sities stesde minis lst have ae sie eee erates 033 henothiofatiretvmolar cee. ec bel So cae i a ae erate tare aa 026 Widthyotiiirstimolarn. coo. 2 s2 se Ses ses) See oe he a ey aa eee 019 ANCHITHERIUM, Kaup. Three species of this genus left their remains in considerable abun- dance in the Miocene of Colorado. One of these is the A. bairdii, Leidy; a second is similar to, and a third smaller than, that well-known animal. They are chiefly known from molar teeth, but greater or less portions of the entire skeleton are frequently found. The following are some of the characters by which the teeth may be recognized: I. Anterior median tubercle not separated from inner, obsolete on the second premolar: A median ridge on each outer lobe, and basal tubercle between the inner.—A. bairdi. II. Anterior median tubercle well separated from inner: Second premolar with anterior median tubercle distinct at both ends; no inner basal lobe.—A. cuneatum. No inner basal lobes; crescents with concave outer faces.—A. ex- oletum. These are the only species of horses known to occur in the Colorado Miocene. ‘ ANCHITHERIUM BAIRDII, Leidy, Ext. Fauna Dak. and Neb., p. 303, Pl. xx. Not uncommon. ANCHITHERIUM EXOLETUM, Cope, spec. nov. Established on a portion of the right maxillary bone, which contains the last premolar and first premolar in perfect preservation and part of the third premolar. These teeth differ from the corresponding teeth in A. bairdii in many respects, resembling in the constitution of their outer lobes some of the symborodonts. The outer faces of these are uni- formly concave to near the shoulder, leaving a very narrow basal ridge and no longitudinal median ridges. The intercrescentic ridge is in- curved and not straight. The anterior middle tubercle is separated from the inner by a deep fissure and grooves to the base; the median is, on the other hand, continuous with the posterior inner. The posterior median is very small. The anterior and posterior basal ridges are small, and there is no trace of basal tubercle between the two medians. Enamel smooth. The size of this animal was probably that of the A. bairdi, but the molar teeth have the antero-posterior diameter greater in proportion to the transverse than in that species. The foramen infraorbitale exterius wore PALEONTOLOGY—MIOCENE PERIOD. A497 is over the front of the fourth premolar; it is above the front of the third in A. bairdii. Measurements. M. Penethonfonroh ana Aiphy molars osc ose spss \a\- 2 ~)- aan ooo te 2 oan> + ooo eR 0.0275 ere n MOL LOMeb Ny MO lateness alerts ce heals s oeyeei nia a ae wan Sele cia els haere wieksce ce ene .0140 WHolshvofstourihymolan seer ee oeecisecete ici ene maison ans schs cats in/seimecatecen 0125 Bleyationoftourthim olan 2-0 specs eos saese ec oiecedse th ebsieccices coos - 0080 Length from front of malar to foramen infraorbitale anterius...-..-.---.--.--- 0140 This species differs from the A. agreste, Leidy, in size about as the A. bairdii. The former is only khown from mandibular teeth. ANCHITHERIUM CUNEATUM, Cope, Paieont. Bull., No. 16, p. 7, (August * 20, 1873,) specimen No. 1. The smallest species of the genus represented by both maxillary bones of one individual; several loose molars and a maxillary bone with teeth of others. In the first-named specimen, the second premolar has the elongate form of the corresponding deciduous molar of A. bairdvi, but I am not sure whether it is the deciduous or permanent one in the present case, as the series only includes the fifth molar. The middle anterior tubercle is directed forward, inclosing an angular fossa with the inner. The latter is separated from the posterior by a basal tubercle, but there is none on the third premolar. The posterior median tubercle is well developed. The outer taces of the outer lobes are con- cave; sometimes with a faint median ridge. The fore and aft cingula are well developed, and the basal parts of the posterior transverse ridges are connected with the posterior median tubercles. Measurements. M. ee rieaehiae Vee Au OLN Ol yet tao os, seta saa ene Seen elatele cicieheie pialcinta aceeee eee 0.0260 PPR snbinche NM EROly INOsall sii. os Fiat ie a eat J clan clam rarenbeninccty ioe med 013 SVU chitin aie IO mI laters ane ncata cies ies are ee reece nies magni HONE eae ols a ciel oisinoe ais .0110 The specimen measured as No. 2 in the original description does not belong to the species. Another specimen contains what are without doubt the permanent third, fourth, and fifth molars. These resemble the corresponding ones of the specimen just described, differing only in being a little smaller. Besides the small size, they differ from those of A. bairdii in the entire absence of the inner basal tubercles, and in the rapid reduc- tion in size of the molars from the fifth forwards. The anterior median lobe is very distinct, and the posterior median small. Measurements. M. Benevarom turd, fourth; and fiftthimolars): 52.5 -a-\sb) -sse cas some pier eee scace) 0.0350 Mengubrotpninde molars sed sete eel atelscaacele aes BCocieseoe COS SeUSHieEE a ecucoac SenabecbosEcse 0038 Par TPLOUIOETXIN) DP NING 2 sole ta la sicis coca c elacime on cial occu oleae veimelaee eo meiwactod oe .0047 MAG LerOMOMONbO1d,, (1M) TOM) senses seis see < else iat ssieisicias lene ciasi=l= 0034 ETD One Vis enacts aac Sass asiceiccecs socslcces es cececiemieemaectocceotee -n0029 Diameter of ball of same-.-....----.--- De Re aortic ie co.08 (anion Oe Once 0011 aa ECV RD LOUNOLSAMG292)5 275 Fest iors o Seas nine s\ccis cid del/eoee V oebebe ds le scmlee ne 0030 The dorsal vertebre, which are appropriately associated with the cer- vicals, have transversely-oval articular faces, and centra without infe- rior keel or ridge. The vertebre are all dorsal, hence the diapophyses have the usual form in the order for costal articulation, and do not pro- ject as far inferiorly as the plane of the lower face of the centrum. It doesnot project beyond the anterior zygapophysis, and the lower half is especially developed as thecostal condyle. Neural spine a keel extending from the front of the arch and rising into a short apex above the articu- 516 GEOLOGICAL SURVEY OF THE TERRITORIES. lar ball. There is a collar round the ball, which i is faintly visible on mine inferior side. Measurements. M. enothyof centrumirss seme cece otk cles Seas at mute «sete ete/ aes meetin se 0.0040 Width of ct Seer e ee Oe ee ied oe ee te ee a ee eee 0018 Depth: Of CUpy ess Ses eee ee ie wer we mini je mje disievetlemtlonteets No owe Site tomtoe Sens 0010 Hlevationofinenralvarchsanberilorlye ss. ce ceee sere see ene ee eee 0015 Elevation of neural spine and arch posteriorly .....----------------+ +--+ -e+- 0043 HBO taliexpan seyinhROmibis 2.2215 5 ss.s/sseinins (Maisie cieinvelele kee eree neo ete ete ee 0047 The dorsals represent several individuals. CREMASTOSAURUS UNIPEDALIS, Cope; Diacium unipedale, Cope, Syn- op. Vert. Col., p. 18. Represented by a sacral vertebra of an individual smaller than any of those of the last-described species, and characterized by the unusual protuberance of the articular ball and absence of flattening of the cen- trum below. Centrum depressed; plane longitudinally convex in trans- verse section. An*’annular groove round the ball. Diapophysis elon- gate, slightly depressed. Measurements. : vo. M. ens thot contrumgssaose- eee eee eee eee Ted ra Srehere tte sw bla eit ee eels ee, a 0.0034 “Diomieten ofeupy) vevteay LOL ta a PLATYRHACHIS, Cope. Synopsis Vert. Colorado, p. 19. Char. gen.—Dorsal vertebrae united by the zygosphene, as well as the usual articulation. Centrum much depressed, flat below. Neural arch depressed, an angle connecting the zygapophyses. Neural spine a keel, projecting beyond the posterior margin in a mucro. PLATYRHACHIS COLORADOENSIS, Cope, loc. cit., p. 19. Char. specif—Ball truncate below its convex face, looking slightly upward. Costal capitular surface semiglobular directly below the an- terior zygapophysis. Neural arch concave between zygapophyses. Measurements. e M. enc thiorthreeMorsalivertebreeee sees ce ee eee eee eee eee 0.0070 - Meno thwotonedorsal verteprasceee eee eee ce eee oe eee eres eee eee re AB : CTANSVETSS “eer Nae seco s Re e WE aa F Diameter of ball, ; BA 5) LO K42 0 epee tA AO Aa I I NE SN .0006 Hilevation of verbebrayysc i) cytes np ate ne ayer ee tafe a 0019 Wadthy between zy capophiysis ese seeeeees cae eee eee ee eee ee eee eee .0025 The size of this species is similar to that of the. two species already described from teeth; but the vertebral articulation is not appropriate to Exostinus with existing lights. OPHIDIA. NEURODROMICUS, Cope. Synopsis Vert. Colorado, p. 15. Char. gen.—Centrum small, with a prominent truncate hypapophysis. Neural arch capacious, the zygantrum wider than the articular cup. Neurapophyses bounding vine canal laterally below che) zygosphene; its cone] _ PALEONTOLOGY—MIOCENE PERIOD. 517 border not angulate behind. Parapophysis eens acutely below centrum. An elevated neural spine. NEURODROMICUS DORSALIS, Cope, loc. cit. Char. specif—Articular surfaces of centrum round; the ball with a slightly upward-looking obliquity. Hypapophysis continued to cup as a prominent carina. A “ridge connecting zygapophyses. Neural spine extending its base forward, so as to stand on the entire length of the neural arch. Measurements. M. ‘SIE ALLE COE aL on 0 ls ae eee NS tne Rl el Pe ed ee ee ne ae oe at ee a 0.0045 : VENUICHL GEES MONS Rt USER Mac) Sets k Us SRP eee aL basal ses 0020 Diameter of Cup,» transverse ._._-. Se aL ee ene ey Bite es Ute tees 0021 Elevation of neural spine above centrum..---....... BS Oe ee Nee sen Regs Pel is ope 0055 Elevation of neural spine above neural arch --.........--..--.-.---2-.------ 0029 Length of hypapophysis below centrum....-....-.. --<- 2-2. cece - 22-2 - eee eee .0012 Mucunvohe hymna NOPMVSIS a... Sse ome «Heese aos Guo ah ohh cis heopenew ene .OO1L The zygantrum is capacious, and the whole neural arch open and light. The species was about the size of the black snake, (Bascanium constrictor.) CALAMAGRAS, Cope, loc. cit. Char. gen.— An obtuse hypapophysial keel most BEGHnene posteriorly. Noridge from the zygosphene; that from the parapophysis wanting or rudimental. Neural spine posterior, short, and obtuse. Neural areh not produced posteriorly ; zygosphene wider than articular cup. Artic- ular surfaces moderately oblique. A concavity separating the articular surfaces of the diapophysis and parapophysis. This genus differs from Boavus, as described by Marsh, in the absente of ridges and concavity of parapophysis. CALAMAGRAS MURIVORUS, Cope, loc. cit., p. 15. Char. specij.—Articular surfaces a broad transverse ellipse. Hypapo- physis terminating in an appressed point. No inferior lateral ridge on centrum; a trace of one on the posterior part of neural arch. Measurements. M. Lama OF GoM TUN s4toh6 -s05 6555 36 opanda odecbe 6 obodcobeob Es code sobaenoskees 9.003 \Wigiiv@e (rilllpeasesssncoe cess nGiscoos boudck dasboy code bass ences coedsy codisec 0017 Deja GE WAM pode sane coed sane coone. soot bEuE Cooo SEES DeaD ceUD LomsBDSsHDosconS lO) Pyadch between parapophyses secs scise Nala = ae est lelteteleea cl cere 045 INCU Wadlidaie = 5 pSo8e0 coneindccooso ss Cob enous coge dao e Ison os00 soscoDSSSO eee 041 VNIG Hin OR Re A COE e Spa cos paca boobSob Sabo raod sacs Aobsicoececeaecor 018 Nia TH OMMAVIEMIa facets soot as Jobe PS A ee See .022 Op LM Gign AVACHLAR ACh -etaamiraeinoeietatsiela ae) )-telelel aime alata) aeeieeeyeaeieie eee .022 WWaGihomen bod fate bret cexfec-eacistelaele «Se alee o cyst ewan secatae ceeee/aemie class a 008 Wwadibvot cuboid: bone fore and att. << 2 i-'2 snisimoe snecseise sess ecenis esctes 023 aa eta e ODOT BOR OE oleae mote olla minis nisla'= = aim minim (omen ee ere aa se sen = 015 Peete AM MebabaAlSUS -elotacll= cella 2 © oe sieleenioehteninoe calcseeln= sles s 170 Transverse width of trochlea of median metatarsus-..---...--.---.---------- 021 PRE ONES OUI ee leat al in efoto mm al mat ae le alate iam 2] ii 042 Po past CLs DLOMUNI ALY = ts 22m Lacie cinivic awielscleleminimaaitaw cbc socecs cise see. 025 SRA OCONEE oa eatin Soc cite cyst bac casitaas adtamnteeiaae nebo cena aciaeie .027 MURCIA PIORIMAllY: 2 )5. (loi. Jo eo edt sec cule whe ademiitd wie tds js fonlaae niente a 025 Ma biln (OP ayia 22 eR EE omens Meera er oer Sri Me) nee meee oy ee een lay Fe; 036 Wid bOs aPbICHIAn {ace 2h. 2..2 2). =. sane nie ones ABO CREO HES Com eee Bas eeete 024 IEREE RUNNER ONO mt clea oe = hem aa oicin ates mrs eet ein a) alpine iam nlp oie e omiem 036 ajith [us ta GIES ahh Gs Se a a eee Peete telat stan ictale eel siete 023 528 GEOLOGICAL SURVEY OF THE TERRITORIES. - Remarks.—Professor Leidy has already observed that the structure of the molars in this genus is in type the same as that of the deciduous molars of Hquus, and that hence Protohippus represents the more primi- tive condition of horse. In further confirmation of this view, I may add that the proportionate size of the head and iength of limbs to size of body is greater than in the recent species of Hquus, resembling in these points the colts of that genus. Acceleration of the growth of the body and prolongation of the face, the same in the widening (fore and aft) of the internal columns of the molar teeth, with retardation of the growth of the lateral phalanges, would express the process of evolution of the modern types of horse. , PROTOHIPPUS PERDITUS, Leidy. Represented in the collections by the entire molar dentition of one cranium ; the greater part of that of another, with incisors and canines; the four median molars of another; two superior molars, with mandible and teeth of a fourth; mandibular dentition of two others, with parts of mandibles and symphyses; and isolated molars of a large number of additional specimens. Without this material, I should have hesitated to separate the two species above described as new; as it is, I have no question that they are well defined, and are not the species described by Dr. Leidy under the name of Merychippus. The two lower jaws at my disposal agree in dimensions with each other and with the superior molars and with Dr. Leidy’s types, with which I have compared them, four of them having the same extent as five of those of the two species above described. In two successional superior molars little worn, one of the inner columns (the anterior) is not yet united with its corresponding crescent, and the borders of the lakes are more plicate than in more worn examples. PROTOHIPPUS PLACIDUS, Leidy. A portion of the skeleton of this species was excavated by myself from the rock of the Pliocene formation, which was accompanied by two teeth, characteristically those of this species, and the only ones I ob- tained which are referable to it. They are readily known from their small size absolutely, and it would seem relatively also. The vertebre are similar in size and proportions; but the metatarsus is materially shorter than that of P. sejunctus, and the phalanges of all the toes, and especially the coffin-bones, considerably stouter. Compare measure- — ments with those given above. Measurements. ; M. Bene th ofimedian, metapodiall bone\jas sae ese sa eee eee ee ere 0.173 Expanse of condyles of lateral metapodials..---. ..---..----...---.--..----- .042 isength ofcorst lateral phalanixyee eases ase senate eee eee meee sae 024 Antero-posterior width of first lateral phalanx .-.--. .----..-------------2e>- .016 Henothtorecotin-=pone medially sees eee eeee eee eee eee cee ee eee ee eee eae O41 Wildthtbetween angles oc. oo Neer oS es ce UE) ye a aes epee 037 Width of articular face.) bse eee Oe i ee Te Ne Ne ee ng aap te .026 Heiehtioncorim=bome) oe lin dee ce yee tee a eee ear eae eee 022 Thus both coffin-bones are larger, wider, and flatter than those of P. sejunctus, a character provided for by the greater lateral distal expansion of the metapodial bones. The shortness of the metapodial bone may be due to the fact of its being a metacarpal; the femoral condyles are adherent to it in the matrix, and there is a proximal facet like that for copr.] PALEONTOLOGY—LOUP FORK EPOCH. 529 the cuboid bone in P. sejunctus. Were the bone a metacarpal, this facet would relate to the trapezoides, a contact which does not exist in either of the genera of three-toed horses, Hippotherium and Anchitherium, ac- cording to Kowalevsky.* ARTIODACTYLA. MERYCHYUS, Leidy. MERYCHYUS MAJOR, Leidy, Anc. Fauna Dak. and Neb., 121. A single superior first molar, presenting some peculiarities perhaps individual. MERYCHYUS ELEGANS, Leidy, loc. cit., 118. A mandibular ramus, with the molars and last premolar; a little larger than Leidy’s specimens from Nebraska. PROCAMELUS, Leidy. PROCAMELUS, sp. Numerous parts of skeletons of a large species without teeth; possi- bly the P. niobrarensis, Leidy. PROCAMELUS ANGUSTIDENS, Cope, Bull. U. S. Geol. Surv. Terrs., No. 1 Oe Represented by the nearly entire mandibles, with most of the teeth of two individuals, and two superior molars referred with probability to the same. This camel is the size of the P. robustus, Leidy, but differs from it in the much narrower teeth, especially the last molar and last premolar, the much smaller first molar, and totally different form of the second premolar. Thus, while the last molar has the same length, it supports an anterior expansion. whose angles are the summits of ridges on the inner and outer sides of the crown, which are wanting in P. robustus. Behind the outer rib in P. angustidens, there is a considerable groove. While the third molar is as large as that of P. robustus, the first molar is strikingly smaller, while the third premolar is about as long, is only half as wide when worn to the same degree. The second premolar, instead of presenting a contracted subconie crown, is longitudinally extended and compressed, resembling closely the third premolar. The molars are remarkably flat on the outer side; each lobe being devoid of a median ridge, and the first and second even wanting that between the lobes. The diastemata are long, and the first premolar is compressed and equidistant between the canine and the second premolar. The dia- stema in front of the canine is not wider than one tooth. The lower incisors are broad and oblique. The lower posterior boundary of the symphysis is almost immediately below the first premolar. Measurements. M. Total length of dental series tio first incisor. ..-.....-. -2s20. eee eens eee nee 0.240 Length from first to third incisor on CrOWNS ..--2. 22-205 cece cee ce ene e ne ence 035 MGHo DEOMI TS h AN CISOL LOLCAMING 2/6 <-yn isc mie intemal sniniea oles) = o\ein\o oie 040 Meuctitrom firstaneisor to first premolar 2255 22 scwsemepeeccnas esenee -o0 073 Length from first incisor to second premolar ...-...--20..----------------+ +0 108 Merona O LYTISCLIES tenis pi aio 2 s/c/ei a xh are clareiare oui ncpane towidclemecles Sees sueiseette 134 MORN Ot DLCIN LATS} —o—4 carters a, =/n1ntaia\s yejmisiarmjavleisieysiaabelemimisiaete tele itienia eletets mle 039 PEED ASCCONCMOLOMOLAL 2 cticciwce mis oc ces © yee’ 564 GEOLOGICAL SURVEY OF THE TERRITORIES. Sericomyia militaris, Walk. (Colorado Mountains); the same insect occurs frequently in Canada and also in the White Mountains. Helophilus bitineatus, Curtis (Twin Lakes), first described from speci- mens brought back by Captain Ross from his polar cruise. I possess it also from Labrador. Helophilus, n. sp.? (South Park, Colorado), which I also received from Fort Resolution, on Mackenzie River, and from other parts of the British possessions. ‘ Chrysotoxum derivatum, Walk., (Colorado Mountains), described by Mr. Walker, from the British possessions in North America. I have specimens from Alaska. Hristalis, two or three species (specimens principally from Twin Lake Creek), which I could not identify with any species I know. Melithreptus, sp. (Twin Lake Creek), very like M. cylindricus, Say, but apparently different. Syrphus corolle (Fair Play), vitripennis (?) and one or two others which I could not identify. Syrphus obliquus, Say, was found above the tree-line. Family GisTRID az. The common horse-bot, Gastrus equi (Colorado Mountains). _ The families Tachinide, Anthomyide, Muscide are represented by a considerable number of specimens, although not so many species. I will notice especially the frequent occurrence of species of Gonia in the mountain-region, and a large Hehinomyia from the plains. The common blue bottle-fly has been found ascending the mountains above the tree line. As the above-named families have not been worked up in the Eastern States yet, it would be premature to attempt any further identification of the species. The most inter esting novelty in the whole collection is a species of the family Blepharoceride, a family rather anomalous in its structure, of very doubtful position in the system, and counting, as yet, but a few members. Only seven species, distributed among five genera, are known from the whole world.* Four of these species are from Hurope; the remaining three are from Ceylon, from South America, and from the United States. The new species from Colorado is thus the eighth in the group, and requires the formation of a new genus, the sixth in the family. Bibiocephala, nov. gen. Closely allied to Blepharocera, but differing prncipally in the venation of the wings, the shortness of the antenne, and the structure of the head. I possess only male specimens. Eyes divided in two halves; the upper one with Raueet and the lower one with smaller facets; these ee two halves are of nearly equal size, (the upper one even seems to be a little larger), and both are clothed with a dense and short microscopic pubescence; besides this pubescence, the lower half is beset with long, erect pile; the two halves are contiguous, and not separated by a narrow band, without facets (at least, I am not able to perceive any such band). The eyes are “All that is known about this family may be found in the paper ‘“ La gna dei eee adi,” by H. Loew, in the ‘“‘Bulletino della Soc. entom. italiana,” vol. i, p. 85-101, tab. ii. Be cee ZOOLOGY—DIPTERA. 565 contiguous; no linear front being perceptible between them. (In Bl. capitata, Lw.,g, the upper half of the eyes is much smaller than the lower one; there is no long pile on the lower half; both halves are sepa- rated by a distinct band, without facets; the eyes are separated by a narrow, linear front. Bl. capitata, Lw., the only American species hith- erto known, was discovered by mein the woods, near Washington, D. C., June 7-10, 1862. In life, the upper half of the eyes was reddish-green, the lower purple.) Ocelli in the usual position, on the vertex (they are proportionally smaller than in Bl. capitata). Antenne short; about equal in length to the longitudinal diameter of the head, 15-jointed ; the second joint has more than double the length of the first, and is curved; the first joint of the flagellum is subcylindrical ; the other joints are short, broader than long, and beset with short pile; the last joint is pointed. (In Bl. capitata, the antennee are comparatively longer, being at least twice as long as the head; the second joint is not longer than the first; the joints of the flagellum are cylindrical, slender, which gives the antenna a filiform appearance. The second joint of the antenna of Bibiocephala resembles that of Apistomiay, the blepharocerid from Corsica, as figured in Loew, loc. cit.,fig. 2.) Face, mouth, and palpi seem to be very like those of Blepharocera ; about the latter two, it would be unsafe to judge from dry specimens (About BI. capitata, which I examined alive, I took at the time the fol- lowing note: ‘The mouth of the female consists of several lancet-like, horny organs, protected by a fleshy, movable under lip ; in tbe male, the horny lancets are absent, or else indistinet. The last joint of the palpi is elongate, slender.” It is very probable that the mouth of Bibioce- phala, § , has asimilar structure; only the last joint of the palpi seems to be proportionally shorter.) Thorax rounded ; thoracic suture appears asa distinct, curved groove on both sides, but is interrupted in the middle (similar to that of BI. capitata). . Hypopygium large, projecting like that ina male Hrax. (The forceps seems tobe analogous in structure to that of Bl. capitata; only the two principal projecting pieces are broader, shorter, aud bfid at the tip.) Feet long, strongly built, and bare, excepting a microscopic pubes- cence; frontand middle parts about equal in length, the last pair much longer, especially through the great length of the femora. Front coxe separated by a considerable space; the second joint of the trochanters very long; middle cox more approximated; the hind ones contiguous. Front tibiz strongly arched, no distinct spurs at the end; middle and hind tibiz straight; the middle ones with two stout, but very small spurs, the hind ones with two short, stout, and very distinct spurs at the end. The joints of. the tarsi on all the feet gradually diminish in length, the first being by far the longest; the last joint, however, is nearly twice as long as the preceding one. Ungues elongated, strong at the basis; their under side, under a magnifying-power of 80-100, shows a dense brush of exceedingly minute, erect hairs, which extends to about half of the under sideon the first pair, and to about three-quarters on the two others. The basis of the ungues shows some longer bristles. - No distinct empodia. (The curved front tibize seem to indicate a habit of throwing the front feet backward and clasping the thorax with them; at least some of the dried specimens were in that position In Bl. capi- tata the feet are comparatively longer and more slender; the front tibiz are straight; the last tarsal joint is not longer than the preceding; the middle coxe are contiguous, ew.) 566 GEOLOGICAL SURVEY OF THE TERRITORIES. Wings (see the figure), im shape, are like those of most of the known Blepharoceride, having the same projecting anal angle, with a rounded end (compare Loew, loc. cit., Fig. 3, 6, and 12). The venation is very like that of’ Blepharocera (loc. cit. Fig. 12), only there is an intercalary longitudinal vein between the first and second veins. It begins near the origin of the second vein, runs alongside of the first, and ends in it a little before its tip. Near its end, it bears a short stump of a vein, which is indistinct in some specimens. The large fork formed by the penultimate longitudinal vein is connected at its basis by a cross- vein with the preceding vein (which is not the case in Bl. capitata). An auxiliary vein is apparent, but it does not reach beyond the origin of the second vein. There is an alula and an alar excision. In the alar excision, between the alula and the anal angle, a peculiar, apparently horny knot, of irreg- ular outline, is apparent, connected with a vein encompassing the alula.* The fringe of hairs bordering the wing is exceedingly minute, hardly visible with a lens of moderate power, except in the alar excision,where the hairs are longer. The surface of the wings is bare to the naked eye, but shows microscopic hairs under a magnifying power of 80-100. The peculiar spider-web-like net-work existing on the wings of all the known Blepharoceride is also apparent here. : The name of the genus is derived from the resemblance of the head, with its contiguous eyes and short antenne, to that of a male Bibio. B. grandis, n. sp., @, black, opaque, clothed with blackish pile; anten- ne black; first joint of the flagellum somewhat paler; thorax with a slight yellowish-gray bloom above, forming an indistinet design and two faint stripes; abdomen black, with indistinct markings of yellowish- gray bloom; the margins of the ventral segments and the under side of the hypopygium brownish-yellow. Halteres pale yellowish-brown. Feet brownish, except the coxse and the basal half of the femora, which are brownish-yellow. Wings with a brownish tinge. Length, 10-11 millimeters; length of the wing, 9 millimeters. Five male specimens taken in the Colorado Mountains in August. OBSERVATION.—In comparing the figure of the wing of this species with that of Protoplasa (Monogr. of N. A. Diptera, vol. iv, p. 317), one cannot help being struck by the great resemblance of both. If we pro- long the interrupted vein in Bibiocephala until it reaches the cross-vein above it, we obtain very nearly the venation of Protoplasa. The differ- ences are (1) the undeveloped end of the auxiliary vein*of Bibiocephala (which is made too weak in the wood-cut) ; (2) the absence of the super- numerary longitudinal vein of Protoplasa (which vein, as I have shown, loc. cit., p. 319, is but the thickening of a fold existing in the same place in Ptychoptera) ; (3) the absence of the cross-veins forming the discal cells. These differences are of far less moment than the analogies. The shortness of the basal cells and the squareness of the anal angle are also characteristic of both wings. The additional vein which distinguishes Libiocepnala from the other Blepharoceridw is the ordinary branch of the second vein, apparent in Protoplasa and very common among the Tipu- lide. Thus, Bibiocephala serves to confirm the hint thrown out by me some time ago (Monographs, &., 1V, p. 3) about the relationship between the Blepharoceride and the Ptychopterina. *Mr. Burgess first called my attention to this peculiar structure, which I also perceive ‘x Blepharocera, and which does not seem to have been noticed before. NOTICE ON THE GALLS COLLECTED BY LIEUT. W. L. CARPENTER. By C. R. OSTEN SACKEN. A.—OAK-GALLS, Colorado Springs, September 25. 1. Leaf-gall, globular, hollow, very similar to the gall of Cynips singu- laris, Bassett, although not identical. The gall-fly, a Cynips, was cut out of the gall inside of which it had died before being hatched. — 2. Leaf-gall of the same class as that of Cynips pegomachoides, O.S., and Cynips erinaceus, Walsh. 3. Bud-gall, different from all other galls known to me in this coun- try; probably likewise a Cynips. It is to be regretted that the species of oak on which these galls were found were not taken note of. B.—WILLOW-GALLS. All the galls examined, from four different localities, belonged to a hymenopterous insect, Nematus (family Tenthredinide), very common on willows. The galls taken July 7 were very young; those taken on East River, August 12, still contained the caterpillar; those of September 1 to 18 wereempty. A lot taken near the Twin Lakes, July 29, had a peculiar shape, and was covered with a whitish bloom. It may have been a different species, although it is undoubtedly a Nematus. C.—COTTONWOOD GALLS. September 18, Clear Creek; gails formed by Aphides at the point of attachment of the leaf-stalk to the leaf. They are very similar to the galls of Pemphigus populicaulis, Fitch, on poplar, and may be produced by this very species. July 15, South Park; woody swelling of the branches. It does not seem to be a gall, as it is entirely solid on the inside. It may have har- bored insects, as several round holes upon its surface seem to indicate, but the deformation is not necessarily caused by the presence of these insects. D.—GALLS ON SAGE-BUSHES. September 8, pupa-shells, found inside of these galls, seem to belong to the genus Trypeta. LIST OF SPECIES OF COLEOPTERA, COLLECTED BY LIEUT. W. L. CARPENTER, UNITED STATES ARMY, FOR THE UNIT- ED STATES GEOLOGICAL SURVEY OF COLORADO, 1873. By Henry ULKE. CICINDELIDZ. Cicindela longilabris, Say. Cicindela purpurea, Olio. pulchra, Say. tranquebarica, Herbst. 568 GEOLOGICAL SURVEY OF THE TERRITORIES. CARABIDA. ~ Elaphrus californicus, Mann. Carabus tedatus, Fabr. Cychrus elevatus, Fabr. Nebria Sahlbergi, Fisch. Pasimachus elongatus, Lec. obsoletus, Lec. Brachinus conformis, Dej. Metabletus americanus, Dej. Cymindis reflexa, Lec. Calathus ingratus, Dej. dubius, Lec. Platynus placidus, Say. chalceus, Lec. Pterostichus protractus, Lec. longulus, Lee. lucublandus, Say. scitulus, Lee. Luezotii, Dej. Amara lacustris, Lec. obtusa, Lee. Amara patricia, Dej. fallax, Lec. erratica, Sturm. terrestris, Lec. subzenea, Lec. polita, Lec. Chienius sericeus, Forst. Nothopus zabroides, Lec. Harpalus caliginosus, Say. amputatus, Say. funestus, Lec. oblitus, Lec. pleuriticus, Kirby. opacipennis, Hald. ellipsis, Lee. Anisodactylus rusticus, Dej. Eurytrichus terminatus, Say. Bembidium Mannerheimii, Lec. lucidum, Lee. quadrimaculatum, Gyll. DYTISCIDA. Laccophilus truncatus, Mann. Colymbetes agilis, Fabr. Colymbetesquadrimaculatus,Aube. | Acilius fraternus, Harris. densus, Lec. binotatus, Harris. Dytiscus marginicollis, Lec. GYRINIDA. Gyrinus affinis, Aube. | Gyrinus maculiventris, Lec. HYDROPHILID. Hydrophilus lateralis, Fabr. sublevis, Lec. Berosus striatus, Say. Hydrobius fuscipes, Linné. SILPHID. Silpha lapponica, Herbst. ramosa, Say. | Necrophorus velutinus, Fabr. STAPHYLINIDA. Creophilus villosus, Grav. Porrhodites, one species. Homalota, one species. Oxypoda, one species. Oxytelus, one species. HISTERIDA. Saprinus oregonensis, Lee. NITIDULID. Carpophilus pallipennis, Say. | Ips Dejeannii, Kirby. so ZOOLOGY—COLEOPTERA. 569 _ DERMESTID&. Dermestes marmoratus, Say. Dermestes nubilus, Say. fasciatus, Lec. BYRRHIDA. Cytilus varius, Fabr. LUCANID. Platycerus depressus, Lec. SCARABAIDA. Canthon vigilans, Lec. Diplotaxis obscura, Lee. ebenus, Say. Tostegoptera lanceolata, Say. Onthophagus latebrosus, Fabr. Polyphylla 10-lineata, Say. Phaneus carnifex, McL. Trichius affinis, Gory. Trox porcatus, Say. EKuryomia inda, Lac. Aphodius ruricola, Mels. BUPRESTIDZ. Melanophila longipes, Say. | Ancylochira confluens, Say. ELATERID&. Alaus melanops, Lec. Corymbites tinctus, Lec. Corymbites morulus, Lec. | TELEPHORIDZ. Chauliognathus basalis, Lee. Podabrus levicollis, Kirby. Calopteron terminale, Say. Photinus lacustris, Lee. angustatus, Lec. MALACHID. Coliops cribrosus, Lec. | Listrus senilis, Lec. Dasytes Hudsonicus, Lee. | CLERID&. Trichodes ornatus, Say. Hydnocera subfasciata, Lec. Clerus sphegeus, Fabr. SCOLYTIDA. Xyleborus septentrionis, Mann. | Dendroctonus obesus, Mann. TENEBRIONIDA. Asida sordida, Lec. ‘Eleodes tricostata, Say. elata, Lec. extricata, Say. opaca, Say. obsoleta, Say. polita, Say. nigrina, Lec. Coniontis ovalis, Lec. humeralis, Lec. Eleodes obscura, Lec. pimelioides, Mann. suturalis, Say. Blapstinus pratensis, Lec. hispilabris, Say. Iphthimus sublevis, Bland. 570 GEOLOGICAL SURVEY OF TH TERRITORIES. CISTELIDA. Hymenorus obscurus, Say. ANTHICIDA. Corphyra Lewisii, Horn. | Notoxus bifasciatus, Lee. Stereopalpus guttatus, Lec. subtilis, Lec. MORDELLID. ~ Mordella scutellaris, Fabr. MELOIDA. Mele near angusticollis, Say. Lytta Nuttalli, Say.! Nomaspis parvula, Hald. spheericollis, Say. Epicauta maculata, Say. Nemognatha lurida, Lec. pruinosa, Lee. GiDEMERID 2. Calopus angustus, Lec. CERAMBYCIDZ. ‘Spondylis upiformis, Mann. Acmieops pratensis, Laich. Criocephalus agrestis, Kirby. longicornis, Kirby. Batyle suturalis, Say. Monohammus scutellatus, Say. Tachyta liturata, Kirby.’ Monilema annulatum, Say. Acmeeops proteus, Kirby. - Tetraopes femoratus, Lec. CHRYSOMELIDA. Adoxus vitis, Linné. Chrysomela dissimilis, Say. Chrysochus auratus, Fabr. Longitarsus, one species. cobaltinus, Lec. Trirhabda attenuata, Say. Doryphora decem-lineata, Say.? convergens, Lec. Chrysomela exclamationis, Fabr. Cassida 6-punctata, Fabr. COCCINELLID. Hippodamia 5-signata, Muls. Coccinella transversoguttata Fald. parenthesis, Say. monticola, Muls. convergens, Germ. picta, Rand. EROTYLID. Erotylus Boisduvalii, Lec.* CURCULIONID. Alophus alternatus, Say. Erirbinus, two species. Cleonus trivittatus, Say. Ceutorhynchus, one species. NOTES. ” 1 Lytta Nutialli.cThe geographical distribution of this insect is extremely limited. It was found in South Park, near the head of the South Platte River, on the Iris tenaz, in an area which might be bounded by a radius of five miles, and was not seen at any other place during the season. 2 Tachyta liturata—Found on the Populus tremuloides and P. balsamifera in great numbers at an altitude of about 8,000 feet. 3 Doryphora decem-lineata. —Colorado potato-beetle. This insect is still marching east- ward; not a single specimen having been seen, west of the dividing-ridge. It is prob- able that, should the potato be cultivated on the western water-shed, it would be free nacen.) ZOOLOGY—-PSEUDO-NEUROPTERA AND NEUROPTERA. 571 from the ravages of this destructive insect for a number of years; but that it would ultimately make its appearance in that region through the agency of the seed. This I believe to be the manner of their introduction to distant localities, as they are slug- gish travelers, and qaite incapable of spreading so rapidly by their own instinct. This belief is further sustained by their continued absence from the Salt Lake basin, occa- sioned by the cheapness of vegetables in the Mormon settlements excludiug the importation of potatoes from Colorado. Not found ata greater altitude than 8,000 feet. 4 Hrotylus Boisduvalii.—Usually found upon the Pinus ponderosa, and never seen at a greater altitude than 9,000 feet. Very abundant in the eastern foot-hills of the Front Tange, but not found on the Pacific slope in Colorado, although it has been collected in Arizona. Nemognatha lurida and Lytta Nuttalli verify the theory of the adaptability of the color of species to their food-plant; the former being found feeding upon the pistil of the Cirsium undulatum, which it so nearly resembles in color as to often escape close scru- tiny; the latter, found upon the Jris tenax, is of precisely the same color as that plant. ; ] W. L. C. REPORT ON THE PSEUDO-NEUROPTERA AND NEUROPTERA COLLECTED BY LIEUT. W. L. CARPENTER IN 1873 IN COL- ORADO. By Dr. H. A. HAaGEen. Family TERMITINA. TERMOPSIS. T. angustieollis, Hagen, Synop., 3, 1. Rufous paler beneath; mouth infuscate; wings dusky hyaline; cos- tal veins rufous; head oval flat; prothorax small, semicircular. Male and female. Var. Nevadensis.—Dark reddish brown, scarcely paler beneath; wings dark, smoky; costal veins blackish-brown. Male and female. Length to tip of wings, 23-26 millimeters; body, 11 millimeters; expansion of wings, 42-44 millimeters. Soldier.—Stout, yellow; head and thorax rufous; head long, oblong, depressed, dark-brown anteriorly; labrum subquadrangular, yellow; mandibles black, long, straight, the pointed tip incurved ; a tooth before the tip of the left mandible; palpi brown; eyes wanting, their place indicated; antennee as long as the head, about 24 joints; the basis of the joints brown, darker on the basal joints; prothorax as large as the head, semicircular; mesothorax and metathorax rounded behind, with a small alar lobe each side, directed backward ; abdomen ovoid ; appen- dages four-jointed, long; last segment with two divergent, anal spines; feet strong, rufous; femora paler yellowish. Length, 16 millimeters. Larva.—Stout, elongated, flattened above, pale; head yellow, rounded; mouth darker; eyes indicated asin the soldier; antennsz 24 jointed; prothorax semicircular, small; mesothorax and metathorax larger, rounded behind, a small alar lobe on each side, directed downward ; abdomen ovoid, the appendages two-jointed, but with indications of two more joints; last ventral segment with two anal spines; feet strong, yellow. Length, 11 millimeters. Nympha:—Size and color of the larva; eyes present, pale; alar lobes large, flat, triangular, horizontally covering the basal third of the abdo men; appendages four-jointed ; anal spines divergent. Habitat—California, San Francisco, (Mann), San Diego, March, April (Crotch); Gulf of Georgia, Fort Steilacoom, Semialunoo (A. Agas- 572 GEOLOGICAL SURVEY OF THE TERRITORIES. siz); British Columbia, Quesnel Lake; Truckee, Sierra Nevada (Crotch); Louisiana (Pfeiffer). The specimens are dry or preserved in alcohol. T. angusticollis is a real western species. I saw only one specimen from Nevada, collected on the western border of the State. Animago from Louisiana, collected by Mrs. Pfeiffer, is preserved in the museum at Vienna, Austria. So far as known, this species is not yet found in Texas or Mexico. Messrs. A. Agassiz and G. R. Crotch observed this species living beneath the bark of pine-trees. The winged imagos differ in color, the typical specimens being rufous, _ though some of them are darker. The single male from Nevada is smaller and the wings not as broad, (one-fortieth inch), and throughout much darker; but amonga number of alcoholic specimens from San Diego and Semialunoo there are some nearly as dark; and, moreover, it is not impossible that the Nevada specimen was darkened by carbolic acid in the collecting-bottle. The discovery of the soldiers and of the other Stages is very important. T. occidentis, formerly supposed to belong as soldiers to ZT. angusticollis, is now to be considered as a different species, the imago of which is still unknown. T. occidentis, Hagen, Synop., 3, 2. Soldier.—V ery feats rufous ; abdomen yellow; head large, nearly as broad as long ; convex above, rounded laterally, depressed anteriorly, the anterior angles prominent, jointed, dark-brown ; antenne 19-jointed, pale, the first and third joint longer, dark brown ; labrum ovoid, yellow ; eyes present, black, oval; mandibles shorter than the head, black, stout, eurved, the left one with a double tooth before the tip. Prothorax broader than the head, large, flat, cordiform, the anterior margin deeply notched ; mesothorax large, broad, with a short, flat, triangular, alar lobe ; metathorax shorter and narrower, the alar cover smaller. Abdomen large, long, ovoid ; appendages very short, conical, 2 jointed; last ventral seg ment with two small spines placed near together ; feet stout, brown ; femora rufous. Length, 19 millimeters. Larva. “Pale yellow; head brighter yellow, rounded, flat above ; anten- ne pale, about 22-jointed ; eyes present, black, well defined. Prothorax as broad as the head, transverse; angles rounded, the hind ones more obtuse; mesothorax of the same size, flattened, transverse, a little broader; on each side a triangular, depressed alar lobe nearly as long as the metathorax; the latter similar but larger; the abdomen broader, thick, ovoid ; the appendages and spines similar to those of the soldier. Feet less stout, yellow. Length, 14 millimeters. Habiiat.—California : Cape San Lucas (Xanthus de Vesey). The type of Walker from the west coast of Central America. The described specimens are preserved in alcohol. The descriptions of the previous stages of T. angusticollis and YT. occidentis prove the difference of the two species. The soldier of 7. occidentis differs by the ‘rounded shorter head ; the two-toothed mandibles ; the prothorax very large, broader than the head, and nearly bilobate; the alar lobes large, flat, horizontal; the appendages very short, two-jointed ; the eyes black, well developed. The larva differs by the alar lobes large, directed down- ward; the prothorax transversely oblong; the abdomen thick, ovoid ; the appendages similar to those of the soldier; the eyes black, well developed. The imago is still unknown; I suppose they belong to the genus Ter- nacex.) ZOOLOGY—PSEUDO-NEUROPTERA AND NEUROPTERA. 573 mopsis ; nevertheless, the well-developed eyes of the soldier, and even of the larva, make this supposition rather doubtful. The genus Termopsis was formed by Professor Heer for fossil species preserved in the amber of Prussia, and in the schists of Oeningen. angusticollis and perbaps T. occidentis are the only known living species of this genus; and their occurrence in North America is the more inter- esting, aS some other remarkable species of the amber-fauna are still represented by similar living species in the fauna of North America. Family PERLINA. PTERONARCYS. Pt. californica, Hag. Synop., 16, 5 (Proc. Bost. Soc. Nat. Hist., xv, 284.) A full description is given in the monograph of this genus in the quoted proceedings. Habitat.—California; Washington Territory, between Rock and Cas- cade Rivers; Lake Winnipeg (Kennicott); Ogden, Utah, from a river , tributary to Great Salt Lake, in June (C. Thomas). Nymphe from the San Luis Valley, Colorado. Ihave seen a number of specimens, dry and in aleohol, male, female, andnympha. According to McLachlan’s state- ment, the wings of the California specimens are very smoky and opaque; perhaps they were darkened by the carbolic acid used by the collectors. Pt. californica is a decidedly western species. Pt. biloba, from Trenton Falls, N. Y., a species, as yet, only represented by the female type in the British Museum, is very nearly related, but accord- ing to McLachlan’s, a different species. Pt. regularis, sp. nov. Male.—Dark-brown, paler beneath ; head dark-brown; the posterior margin, two large lateral spots connected by a line behind the ocelli, two flattened, round tubercles a little before, and the anterior margin all dull-yellowish; lateral margin carinated up to the tubercles ; three ocelli well developed; labrum small, brown; antenne slender, half as long as the wings, brown; the basal joints yellowish beneath. Pro- thorax as broad as the head, nearly square, the anterior angles sharp, the posterior rounded, dull-brown ; a very fine median yellow line only indi- cated, and on each side some curved elevated marks. Abdomen pale beneath; setz (partly broken) shorter than the abdomen, dark-brown, dull-yellow at the bases, stout, the five basal joints very short. Feet brown, pale beneath; wings smoky, hyaline; veins strong, dark-brown ; areolation square. The vulvar lamina as broad as the segment, rounded in front, the middle more produced, as long as the segment, notched on the tips, black ; on each side at the base is a small triangular tubercle. Length to tip of the wings, 19 millimeters; alar expansion, 33 millime- ters. - Habitat.—Truckee, Sierra Nevada; Nevada, June 10 (Crotch). I have seen only two specimens. Pt. badia, sp. nov. Pale-brown; head dull-yellowish, with a large square black spot around the oceili; antennz brown, paler beneath. Prothorax square, the anterior margin rather rounded, the angles right, pale-brown, with darker shading on each on the elevated marks. Abdomen pale above, darker in the middle, pale-brown beneath; the apical margin of the penultimate ventral segment largely excised; the dark-brown middle 574 GEOLOGICAL SURVEY OF THE TERRITORIES. part of the segment somewhat produced, without reaching the last seg- ment; sets pale-brown; feet darker brown; wings yellowish hyaline, with a dull-yellow stigma; veins brown. Length, 17-19 millimeters; alar expansion 31-33 millimeters. Habitat.—Bridger Basin, Wyoming (Garman); Cache Valley, Utah (C. Thomas); Colorado Mountains, August (W. L. Carpenter). I saw only three females, in a very bad condition, in alcohol. The two species above described are the dwarfs of this genus; the smallest species known, Pt. proteus, having twice the length of Pt. regularis and Pt. badia. The gills are well visible in the alcoholic specimens of Pt. badia, 26 pairs in number, to wit, 6 between the head and the pro- thorax ; 6 between the prothorax and mesothorax ; 6 between the meso- thorax and metathorax ; 2 between the posterior feet; and 6 on the basal segments of the abdomen. The maxillary palpi are longer than the mouth, the basal joint short, the other long, equal, thicker at the tip; the labial palpi are similar. The palpi show a similar formation as the apical joint in the phryganideous genus Hydropsyche. The external membrane is cut or split in a somewhat spiral manner, so as to give to every joint the appearance of a large number of small joints imper- fectly soldered together. This formation of the palpi belongs to all the species of Pteronarcys, and is exceptional for this genus only in the whole family of Perlina. . Pi These two small species agree in all characters with the larger species, at least so far as the females are concerned, as the males are still un- known. The wings are divided into quadrangular cells, perhaps a little more regular than in the larger species. The venation of Pteronarcys seems to resemble the most the remarkable fossil genus Miamia. ACRONEURIA. A. abnormis. Perla abnormis, Hagen, Synop., 17, 1. This species appears to vary in avery high degree. The late B. Walsh, after repeated observations of living specimens, confirmed varia- tion in size and color, in the reticulation of the wings and in the number of the quadrangular areoles, which are sometimes nearly or altogether wanting; the shape of the prothorax and the vulvar lamina of the female, commonly of a constant shape in this family, offer also slight variations in this species. The male has usually long and well-developed wings ; however, two short-winged males now before me seem to belong to this species. The material in my collection of dry and alcoholic specimens, though rich in specimens from different localities, seems to be not yet sufficient to decide the question whether we have here several very closely-related Species or simply varieties of A. abnormis. Two females from South Montana and a male from Snake River, Southeastern Idaho, collected by Prof. C. Thomas, differ as follows: The colors are darker, the abdomen yellow beneath, on each side dark- brown. The male, in worse condition than the females, is a short-winged one; the shape of the prothorax somewhat different, perhaps only altered by the bad preservation. The vulvar lamina of the two females is more produced than usual, covering one-half of the following segment ; the apical margin is nearly semicircular, notched very little in one female, and not at all in the other. A cast nympha-skin from Hagle River, Colorado, August 30, collected by Mr. Carpenter, belongs to a very large species. Length, 33 milli- meters; sete, 26 millimeters. There is nothing known concerning the nacry.] ZOOLOGY—-PSEUDO-NEUROPTERA AND NEUROPTERA. 575 previous stages of the North American Perlina ; even the different larva and skins in my collection are not yet thoroughly studied. After a closer comparison with a nympha-skin of A. abnormis, communicated by B. Walsh, I believe that the nympha-skin from the Eagle River belongs to the same genus, but certainly to a different species. It is not so much spotted; the apical half of the wing-cases is pale, without the black band, so conspicuous in A. abnormis ; the abdomen is dark- brown above, without the regular paler marks of A. abnormis; the basis of the blackish sete is pale instead of the throughout dark color of the sete of A. abnormis. Even the size of the skin seems too large for the known American Perlids, except for some very large specimens of A. abnormis, collected at the Saskatchewan River.’ Habitat— Assuming the above-described specimens to belong to A. abnormis, this species would have a very wide distribution. The norih- ern limits known are the Saskatchewan and Peel River and Canada; the southern limits, Georgia, and perhaps Mexico; it is known from all Eastern States on the Atlantic, and from many States between the Atlantic and the Rocky Mountains. DICTYOPTERYX. D. signata, sp. nov. Yellowish-brown, pale beneath ; labrum pale-brown; head flat, with two irregular brown stripes, connected transversely before the eyesin a manner to form an anterior large yellow spot, trilobate behind; space between the stripes with an anterior rounded spot, connected with a smaller triangular one on the hind border; a large yellow spot on each side near the eyes. Antenne pale-brown; first joint blackish-brown above; second and third pale; palpi pale. Prothorax as broad as the head, nearly square; brown, with a large yellow median band some- what dilated at the ends; on each side three carved marks, formed by rather irregular black polished scars; lateral margin straight, dark. Abdomen dark-brown above, pale-yellowish beneath; whitish around the base of the feet; segments darker at the base. Feet pale-brown, femora with an external vitta and a ring before the knee; base of the tibiz and tip of the tarsi dark-fuscous. Sete pale brown, darkest at the tip of the joints. Wings with a grayish-yellow tinge, darker on the costal margin; veins brown, darker, and very irregular on the tip of the wing, five or four, or even less, antecubitais; wings of the male as long as the abdomen, or one-third or more shorter; the apical areolets very irregular. Male.—The last dorsal segment yellow; the apical margin recurvate, transversely cariniform; thickened, emarginate in the middle, scabrous, and rather villous exteriorly; appendages yellow; the superiors are small recurved lobes; between them the larger inferiors, darker on the triangular tip, which is sharp and a little emarginate beneath, just before the tip; an ovoid membrane between the inferiors belongs per- haps to the penis; last ventral segment produced between the sete with an elliptical margin. . Female.—Last dorsal segment obtusely produced in the middle of the apical margin, with a median longitudinal impression; vulvar lamina large, rather inflated on the antepenultimate segment, forming two free circular lobes, very near together, beneath the penultimate segment. Length with the wings, gf, 13-17 millimeters; 9, 18-21 millimeters. Alar expansion, ¢, 16-26 millimeters; 9, 30-40 millimeters. Length of the sete, 11 millimeters. 576 GEOLOGICAL SURVEY OF THE TERRITORIES. Habitat.—¥oot-hills, Colorado, September, and mountains on the Pacific slope, August 16 to September 6. Several specimens in alcohol. This genus is new for the American fauna; all species known belong to Europe and Siberia. This*new species is far more interesting as an exception, bearing gills in the imago-state. There are on the ventral side five pairs of gills, formed by white, fleshy, blind sacs; two pairs on the under side of the head; the first pair widely separated on the basal part of the submentum ; the second pair in the articulation with the prothorax; both pairs straight, placed transversely, looking outward. The three other pairs on the thorax, always before the feet, but sepa- rated from them, being placed just in the articulation of the segments ; the three thoracic pairs are incurved. The occurrence of gills in the imago-state of D. signata is the more exceptional, as all the hitherto-known species are without them. At least, a close examination of dry specimens of all the species in my col- lection (only one of Siberia is unknown to me) did not disclose anything similar to the gills in D. signata ; Dr. Gerstaecker, in a recently-pub- lished paper, also states the absence of gills in living specimens of D. intricata and D. alpina. Formerly, the genus Pteronarcys was the only known exception for its gill-bearing imagos among the class of insects ; now, besides the above-described Dictyopteryx, there are two other gill-. bearing Perlid genera mentioned by Dr. Gerstaecker, Damphipnoa lichenalis from Chili, a genus closely related to Pteronarcys, and Nemura cinerea and N. nitida, with its male N. lateralis, both from Europe. The papers by Dr. Gerstaecker are published in the Festschrift zum hundertjachrigen Bestehen der Gesellschaftnaturforschender Freunde, Berlin, 1873, 4to, p. 60, with figures ; and Sitzungsbericht derselben Gersellschaft, October 21, 1873, p. 99. ’ ISOGENUS. FT. elongatus, sp. nov. Female.—Brown; head with a posterior, triangular, yellow spot, extended on each side of the occiput ; two small, ill-defined, yellow spots near the antenne and eyes; antenne brown. Prothorax as broad as the head, quadrangular; the angles sharp, with a large, yellow, median band, narrower before. Abdomen and feet brown; seta brown; base of the joints paler. Wings long, hyaline; veins brown, with a pale- yellow tinge around the costal apical veins; costa pale; submedian areolet larger toward the tip, with seven transversal veins; the ante- rior vein of the submedian areolet somewhat curved. Vulvar lamina ‘large, the base separated from the segment by a deep furrow in form of a transversely-enlarged W ; apical margin nearly straight, covering only a little of the following segment; the lateral angles rounded; a small notch in the middle. Length, with the wings, 24-28 millimeters. Alar expansion, 40-44 millimeters. Habitat.—Foot-hills, Colorado (Mr. Carpenter); Ogden, Utah (by C. Thomas). Aleoholic specimens. J. elongatus is very similar to I. fron- talis, but in this species the anterior vein of the submedian areolet jS Straight, and the anterior margin of the vulvar lamina rather incurved. I. colubrinus, sp. nov. Brown; head with a posterior, triangular, yellow spot; part before the ocelli yellowish; antennz blackish-brown; prothorax rather smaller than the head, quadrangular; angles sharp, with a yellowish median band, a little narrower betore ; abdomen and sete dark-brown; feet pale- brown, tips of the femora and tibie darker. Wings hyaline; veins aoe ee Pa acy] ZOOLOGY—-PSEUDO-NEUROPTERA AND NEUROPTERA. 577_ pale-brown ; costa, and its transverse veins, pale ; submedian areolet less enlarged on the tip ; the anterior vein less incurved ; vulvar lamina simi- lar to I. elongatus, but larger, subbilobed, the notch reaching nearly to the basal furrow, and the apical margin nearly circular. Length, with the wings, 22 millimeters; alar expansion, 38 millimeters. Habitat.—Snake River, Idaho (C. Thomas). I believe that some speci- mens from the Saskatchewan River, from the Slave and Winnepeg Lakes, all in my collection, belong here. The males are a little smaller, but long-winged. The comparison of dry and alcoholic specimens is so difficult that it seems more prudent to consider the identity of the speci-, mens as still doubtful. PERLA. P. sobria, sp. nov. Female—Head dull-brown near the prothorax; the anterior part pitchy-black ; three large yellow spots between the eyes, each side one near the border, and a middle rhomboidal one; three smaller spots on the clypeus between the antenna, each side, a pale, whitish one near the border, and a middle quadrangular, yellow one just before the ante- rior ocellus, bordered on each side by a shining-black stripe; antennz black, brownish beneath at the base. Prethorax as broad as the head, quadrangular, broader than long; hind angles less sharp, pale-yellow on each side, with a large, ill-defined rugulose band; a fine, impressed, median line with a spot in the middle, and a fine, transversal line just before the anterior and one before the posterior margin, all black. Me- sothorax and metathorax shining-black above; abdomen brown on the under side, paler at tip; head and thorax brown beneath, with a large, black spot on each side before the second and third pairs of feet; sete pale-yellowish. Feet dark-brown; wings hyaline, scarcely fumose; veins strong, blackish-brown, finer in the costal space; vulvar lamina large, bifid, the outer edge of the two lobes rounded; before them a small tubercle. ‘ Length, with the wings, 14 millimeters; alar expansion, 26 millime- ters. Habitat.—Colorado Mountains, Pacific slope, August (Mr. Carpenter). One female, in poor condition. P. ebria, sp. nov. Female.—The single specimen, in bad condition, is very similar to P. sobria in colors and in shape. The genital parts are well preserved and the vulvar lamina is entirely different, a long oval lobe without any notching of the apex. So far as known, this important part never varies in such a manner, and it would be impossible to unite both specimens in one species, notwithstanding their great resemblance. Habitat.—The same locality as P. sobria. é Es (?), sp. There is a third species from the same locality in worse condition still. It is a little smaller, the head and the prothorax somewhat different. As the abdomen is wanting, I prefer merely to indicate the occurrence of a third undescribed species. CHLOROPERLA. A small Chloroperla, of the size of C. cydippe, from the foot-hills of Po cae belongs to a new species, but is too much damaged to be escribed. 37 GS 578 GEOLOGICAL SURVEY OF THE TERRITORIES. Family EPHEMBERINA. EPHEMERA. E. compar, sp. Nov. Male imago.—Light-brown; head blackish-brown; antenne pale-yellow; a broad, pale-brown, dorsal band on the thorax ; each side of the protho- rax blackish; abdomen above on each side with two, black, longitudinal lines and two more in the middle of segments 6 to 9; last segment with two large, ill-defined, black spots; abdomen beneath on each side with one black, longitudinal line; penultimate segment with a large, quad- angular, black spot; seta very long, pale-brown, the articulations hardly darker; appendices pale brown, long, arcuated on the tip; the two apical joints short, the last shorter; feet pale-brown; the anterior pair very long, black; the femora brown; fore-wings hyaline, with a yellowish tinge; veins dark-brown; the apical half of the two costal spaces dark-brown, and the basal half of the second costal space rather fumose; a series of four small, black spots in the middle of the wing near to the costa, another spot near the base of the wing, and one near the tip; hind-wings of the same color, with a large apical brownish band ; some of the veins in the middle of the wing finely clouded with black. Length of the body, 15 millimeters; alar expansion, 32 millimeters ; length of the sete, 30 millimeters. Habitat.—Foot-hills, Colorado (Mr. Carpenter). This species is very similar to H.-lutea, Burm. (2. lineata, Wat.) ; as I have seen only one male, I believe it to be more prudent not to identify the American with the European species, the more so as some differ- ences, though not important ones, are to be found. LH. lutea has the third and fourth joints of the appendices of equal length, and together two-thirds the length of the second joint. #. compar has the fourth joint shorter than the third, and both together one-third the length of the sec- ond joint. Butas the only male of #. compar is dry, and as the measures for H. lutea are taken from living specimens, the differences may not be certain. The discovery of H. compar fills a gap in the fauna of North America. There are four species of Kuropean Hphemere nearly related — to each other. Till now only three species were known in the North American fauna representing three of the European species, and the dis- covery of EH. compar imitating the fourth European species makes the parallelism of the Ephemerid fauna of both countries complete. As the other three American species were formerly not well described, even some of them erroneously identified, I believe it is worth while to give here a more detailed description of them. It is presumed that at least two of them will be discovered within the area of country embraced in this paper. ; HE. decora, Hagen (Synop., 38, 1). Male imago.—Luteous ; head in the middle, prothorax on each side, dark-brown; antenne pale; abdomen above with four large, beneath with two narrow, black lines; sete pale, the articulations fine, brownish 5 appendages pale, the two last joints nearly equal in length, taken together about half of the second joint in length; anterior feet yellow ; femora brown, darker at the tip; tibia at base and tip, tarsal joints at tip, blackish; the other feet pale; fore-wings hyaline, with a faint yel- lowish tinge, light-brown on the two costal spaces; transversal veins brown, faintly clouded near the costal margin and in the middle of the wing ; some larger brown spots in the middle near to the costa, and one uacex) ZOOLOGY—PSEUDO-NEUROPTERA AND NEUROPTERA. 579 smaller near to the base; hind-wings hyaline. This male had appar- ently recently cast the skin, and is identical with the fragment of the type described in the synopsis. The type of B. Walsh in my ccllection is smaller (alar expansion, 23 millimeters), darker in color, but otherwise not different; the hind-wings have some transversal veins clouded, and a few blackish spots. A male from British America has the size of the male above described, but the colors of the specimen from B. Walsh. Female imago.—Uuteous ; a darker line on each side of the prothorax ; abdomen above with two larger triapgular black spots on each segment, beneath with two longitudinal black lines; sete pale; feet luteous; femora of the anterior feet brownish, tip of the joints brown ; wings simi- lar to the male, but the costal margin nearly hyaline, the spots smaller ; some few spots on the hind-wings. A second female from British America is similar to the first. Subimago, male and female.—Grayish-luteous; sete pilose; wings dusky ; spots the same as in the imago, none on the hind-wings; costal space a little darker. Imago: length of the body, 6, 10 millimeters; ¢,11 millimeters ; alar expansion, ¢, 23-27 millimeters; 9?,30 millimeters; length of the seta, ¢, 30 millimeters. Subimago: length of the body, 13 millimeters; alar expansion, 30 millimeters ; seta, 2, 15 millimeters. Habitat.—New Haven, Conn., 6; Norway, Me. ¢,9; Rock Island, Ill., ¢; Chicago, Ill, 9; Virginia, ¢; British America, 3, ?, imago and subimago. The wings of the two males from Virginia have darker spots, but prob- ably belong to this species. HH. compar is nearly related to 2. decora, but is a little larger, brighter-brown, the anterior feet black, with the femora brown, the seta without blackish rings on the joints, the appendages visibly longer, the wings more yellowish, the costal margin brown, the spots smaller, the hind-wings with a larger apical brownish band. This species is the EH. decora of my synopsis, and according to the notes made by me in 1857, in the British Museum, also Walker’s 2. decora, I do not find the antenne blackish ; in the type-specimen of my synopsis, the antenne are now wanting. I have no doubt about the rights of this species, which imitates well the European ZH. glaucops. The type of Mr. Walsh is the smallest specimen known, but, according to his paper, another male from the same locality was larger (alar expansion, 25 millimeters), nearly as large as the specimens above described. E. guttulata, Pictet, Ephem., 135, 4, Pl. 8, Fig. 4. Male Imago. Syn.—Z., sp. nov., Hagen, Proc. Ent. Soc. Philad., 1863, 177.—Trans. Ent. Soc. London, 1873, 393.—Eaton, Monogr., 71 (var. of L£. myops). Female imago.—Head and thorax Iuteous; a brown band each side on the prothorax, some darker spots on the thorax; abdomen pale-yellow, last segment brownish on the sides; set pale-yellow, faintly pilose, the articulations annulated with black; anterior feet yellow; femora, base, and tip of tibie, tip of tarsal joints, brown, the other feet yellow ; fore- wings hyaline, fumose on the costal and apical margin; transversal veins except on the third part of the hind border strongly clouded with black ; a Jarger confluent elongated black spot in the middle of the wing; hind- wings on the apical margin fumose, the transversals on the costal mar- gin, and some apicals strongly clouded with black; a larger confluent black spot in the middle, and a small one near the base. 580 | GEOLOGICAL SURVEY OF THE TERRITORIES. { Length, 19 millimeters; alar expansion, 42 millimeters; setae (broken), about 12 millimeters. Habitat.—New York, by Osten Sacken. . This is the female Eph. sp. nov., quoted in Proceed. Ent. Soe. Philad., 1863, 177, as resembling EZ. Danica of Europe, and by Mr. Eaton in his Monograph 71 as a probable variety of H. myops, a statement refuted by — me in Trans. Ent. Soc. Lond., 1873, 393. I am now convinced that this female belongs to #. guttulata, Pict. The long anterior feet prove Pictet’s specimen to be a male imago; the other feet and the abdomen are wanting. ‘The colors and the pattern described by Pictet agree well, except the anal part of the fore-wings, nearly hyaline in the described females, faintly spotted in Pictet’s type. The bright-yellow anterior feet in Pictet’s description and figure (the number of joints is erroneous) represent very well this species, and are not to be seen in any other species. Pictet gives no dimensions, but the figure is without doubt of natural size, the alar expansion 36 millimeters. The locality of the type is not known; it was presented by Mr. Conlon, and may be, as many other species, communicated by this naturalist from the Western Hemisphere. In my Synopsis 38, I supposed LH. guttulata to belong probably to EH. natata, and Mr. Eaton, Monogr. 69, gives both species as synonymous. The type was not in Pictet’s collection ; at least, it is not among the species seen by Mr. Eaton in the collection (Monogr., p. 11). The resemblance to #. Danica consists in the yellow-colored abdomen. The wings of HL. guttulata are more spotted, the abdomen less so or not at all. The colors of the abdomen feet, setse, and wings are very different from those in H. natata. - HH. natata. Syn.—Lalingenia natata, Walk., Cat., 551, 13, fem. subim. E. simulans, Walk., Cat., 530, 5, male subim. E. natata, Hagen, Syn., 39, 4. E. simulans, Hagen, Syn., 38, 2. LH. guitulata, Katon, Monogr., partim. Dale imago.—Dark-brown; prothorax each side with a black band; abdomen brown, above with large, serrated, black spots; seta pale-brown; articulations of the basal joints faintly marked with darker rings (partly broken); anterior feet brown; tip of joints darker; femora blackish ; the other feet paler brown; appendages pale-brown, joint 2d and 3d darker on tip; 2d joint arcuated, not twice as long as 3dand 4th together; 4th half the length of 3d; wings hyaline; costal margin rather smoky; most of the transversal veins, except in the hind part of the wing, clouded with black; several larger quadrangular black spots in the middle of the wing and near to the base; hind-wings with the apical margin smoky ; many transversal veins clouded with black, and several small spots blackish. Female imago.—Similar to the male; thorax brighter brown; wings hyaline on the costal margin, except on the base, not so strongly clouded With black. Male and female subimago.—Colors more dull; wings grayish; anten- ne black; setz dark-grayish. Length, ¢,13 millimeters; 9,15 millimeters; alar expansion, ¢, 32 millimeters; 2,40 millimeters; sete 2, 15 millimeters. Halitat.—Saskatchewan River, British America, by R. Kennicott; a large number, in very bad condition; both sexes imago and subimago, Saint Lawrence River and Saint Martin’s Falls, Hudson’s Bay, by Walk- \ nacen.}) ZOOLOGY—-PSEUDO-NEUROPTERA AND NEUROPTERA. 581 er; Chicago, by Osten Sacken and Woodwell; Maine, in Harris’s col- lection. This is the H. natata of my synopsis. The species imitates FZ. vulgata, of Europe, but the wingS are more grayish than brownish. It differs from LH. decora by the larger size, the darker marked wings, the less annulated set, the relative length of the joints of the appendages. At least, there can be no doubt about the difference of my HL. natata and E. decora, brought together even with LH. guttulata, as belonging to the same species, by Mr. Eaton. It may be interesting to publish here a letter to the late Prof. L. Agas- siz by Mr. George E. Woodwell, from the Tribune office, Chicago, Ill., J uly 23, 186 (2) (number not filled). The letter contained several dry speci- mens, imago and subimago, of HL. natata: I send you a number of specimens of a fly which annually visits our lake-cities, and which has the present summer appeared in larger swarms than ever known before. During the recent hot nights they have poured in from the lake in myriads, rendering it necessary in lighted buildings to close the windows and doors in order to escape their visitation. For several nights past, they have thus swarmed upon us; and ibe morning would witness about the posts of the street-lamps large heaps, in some instances three juches deep, aud covering an area of two or three yards square. Couriously enough, the imitating species from Europe, B. vulgata, swarms in a similar manner ; and Scopoli tells us that the farmers in Krain are not contented unless they are able every year to bring a num- ber of cart-loads as manure upon their fields. HEPTAGENIA. H. brunnea, sp. nov. Male imago.—Brown, the thorax and the body beneath ipllees head blackish ; prothorax deeply notched behind, with an elongated blackish spot on each side, and a similar one on the mesothorax ; metathorax bright-yellow between the wings. Abdomen brown, the segments with a — darker ring on the tip; sete long, grayish-brown, darker at the base, the articulations scarcely darker ; appendages long, cylindrical, darker brown, four-jointed; first joint very small; second somewhat longer than the apicals together, which are of equal length; piece between the appendages notched ; penis long, bifid, divergent. Jemur paler on the tip; the other legs pale-brown ; femora with a darker external line; tarsidark. Wings hyaline; veins brown; some transversal veins on the costal margin pale. Female imago.—Similar to the male. Abdomen pale, on the upper portion of each side a series of triangular black spots and a longitudinal between them; beneath, on each side a series of black lines ; sete pale, articulations black; egg-valve broad-elliptical; legs similar, the four posterior with the tarsi pale; femora darker, pale at the base and tip; wings similar, the transversal veins in the costal space pale, very fine, not reaching the costa. Length, $,10 millimeters; ¢, 12 millimeters; alar expansion, ¢, 30 millimeters ; ?, 34 millimeters. Habitat.—One pair from Nevada, Truckee, in Sierra Nevada range, June 10 (J. R. Crotch). HH. pudica. Syn.—Lphemera pudica, Hagen, Synop., 39, 5. Female subimago (dry, just casting the skin).—Grayish-brown; head large, triangular, flattened, luteous; eyes distant, black ; pusterior ocelli large, the anterior small; antennz short, stout, brownish, paler at the 582 GEOLOGICAL SURVEY OF THE TERRITORIES. base; the hind border of the occiput straight. Prothorax short, hind- margin deeply notched, nearly bilobed, pale, shining ; thorax thick, pale, shining on the middle denuded parts. Abdomen stout, dull-yellowish above, with black oblique spots on each side of the segments, and some finer lines on the ventral side. The described parts, except the anten- ne, are out of the nympb-skin belonging to the imago. Abdomen of the subimago pale, last dorsal segment with a small median projection ; sete strong, faintly pilose, long, grayish-brown; a large mass of eggs is protruded, but the parts are not in good condition ; feet pale, grayish- brown, well developed, tarsi five-jointed ; anterior wings large, opaque, pale yellowish-gray; the longitudinal veins yellowish, the transversals brown, somewhat fumose; hind-wings more yellowish, the apical border larger, grayish; reticulation similar to Ephemera. Length, 14 millimeters; alar expansion, 42 millimeters; sete, about 30 millimeters. Habitat.—Washington (Osten Sacken); foot-hills, Colorado, August (Carpenter). Both female subimagos, and both in very poor condition. In the type of the species, the femur, on the (only present) anterior foot, with a dark-brown ring in the middle. LEPLOPHLEBIA. LL. pallipes, sp. nov. ; ! Female imago.—Brown, shining ; head light-brown; antenne grayish, brown at the base; around the ocelli black; prothorax notched behind; ‘ mesothorax black, shining above; abdomen dark brown, segments on | tip with a darker ring; seta broken; vulvar lamina long, broad, bifid, . the lobes elliptical; legs thin, pale-whitish, the femora darker on tip; a wings hyaline, transversal veins very fine, nearly invisible, except a few i on the tip of the costal margin. Length, 6 millimeters; alar expansion, 15 millimeters. Habitat.— Nevada, Truckee in the Sierra Nevada (Crotch). Tarsi, 4-jointed; the reticulation and the shape of the hind wing sim- ilar to the wing of L. helvipes, figured by Mr. Eaton (Monogr., Pl. iv, 26, d.). Nympha-skin (perhaps belonging to Heptagenia pudica).—Body broad, flattened ; head small, half as long as broad, visibly enlarged in front; Ahe hind part inflated with a rounded tubercle each side; the front bor- der cut off straight; the sides oblique; the front angles rounded ; the whole border fringed with wooly hairs. Antenne short (not complete), a little longer than the front border; two stronger basal joints, second longer; and a conical seta, the joints of which could not be ascertained. The head (for the escape of the imago) split transversely behind the antenne, and the occiput in the middle; the part above the mouth- parts (viewed from the front) is straight, and superseded by the de- seribed flattened border, which forms a triangular projection on each | side; labrum transversely oblong, yellow, blackish on each side at the i base; mandibles and maxillz strong, yellow, with blackish apical teeth ; Mi labium transversely elliptical, four-lobed, a 2jointed large palpus each side. Thorax large, nearly twice the breadth of the head, pale- gray, with some brown spots; prothorax flat above, short, larger’ be- Ou hind, the angles sharp; each side near the middle of the flattened bor- der an exserted, conical, sharp spine; meso- and metathorax rounded above, with triangular wing-cases covering the basal segments of the abdomen. The wing-cases are separated by the notched hind border of @ the metathorax; the cases of the posterior wings are not visible, and = seem to be connected with the anteriors in the manner of Betisca. Abdomen a little longer than the other parts of the body, broad, flat- nacex.) ZOOLOGY—-PSEUDO-NEUROPTERA AND NEUROPTERA. 583 tened; the segments, 2 to 9, produced on each side, in a large triangular process, bent behind, very sharp at the tip; abdomen pale-gray on each side, above a series of brown spots, with some in the middle between them; the triangular processes, on the segments 4 to 9, dark-brown, with a pale ring before the extreme tip, which is again blackish; segments 4 to 7, above each side, with a large flattened orbicular gill inserted be- neath the hind border of the segments, where the lateral process begins; all lateral processes covered and fringed with wooly hairs; last segment short, transversely oblong; the dorsa! apical border produced in the middle; the three setz a little shorter than the abdomen, equal, slender, pale; the fourth joint with a black, apical ring; on the apical third four segments black, also the tip; set fringed with long hairs; feet flattened ; the femurs dilated in the dorsal middle, ending in a superior spine, pale with three brownish bands; tibize black at the base and the apical half; tarsal joint black on the basal half and on the tip; the singie claw pointed black at tip. Genital parts of the male en the ven- tral side of the ninth segment, forming on tip a transversal lobe, with a triangular longer ene on each side, and a little before an elongated bifid ie ; the female has the ninth segment produced in a larger elliptical obe. Length, without sete, 15 millimeters; sete, 7 millimeters; greatest breadth of the abdomen, 5 millimeters. Habitat.—Colorado, mountains and plains, July 19, September 19, Mr. Carpenter. Three skins of the nympha. The form of the nympha is a very extraordinary one; so far as I know, the next related is the nympha of Heptagenia, and considering the large size it would not be improbable that this nympha belongs to H. pudica. Family ODONATA. Subfamily LIBELLULINA. The genera Pantala, Tramea, and Plathemis are not yet represented in the collection of the expedition; nevertheless, it is very probable that some of the widely-spread species of those genera occur in the Territories. P. hymenea, T. lacerata, and Pl. trimaculata will, perhaps, be discovered there. LIBELLULA, LI. 4-maculata, Hagen, Synop. 150, 1. Habitat—Snake River, Idaho, and Ogden, Utah, collected in 1871 by Mr. C, Thomas; Bridger Basin, Wyoming, by Mr.8. W. Garman. This species migrates iu immense flocks in the Saskatchewan district, in Canada, in Wisconsin, and around Lake Michigan, just as in Europe and in Siberia. Stowe, Mass., is the most southeastern limit for the United States; it is very common in Northern and Central Europe and in Northern Asia as far as Kamtchatka. L. nodisticta, Hagen, Synop., 151, 3. Male adult.—Pruinose, clothed with white hairs. Labium yellow, with a large black band strongly coarctate just before the tip; labrum luteous, a blackish border on the anterior margin, not reaching the sides, and some ill-defined brownish spots in the middle and on the basal margin; rhinarium and epistoma luteous; front brassy, black above and before, with a bright-yellow spot on each side near the epis- toma. Antenne black; vertex brassy-black, inflated, narrower at the 584 GEOLOGICAL SURVEY OF THE TERRITORIES tip, the angles not sharply pointed, the vertex roughly punctured in front ; occiput brown ; eyes black behind, clothed with white hairs, a large yellow inferior spot near the margin, and a smaller quadrangular one above it; thorax black, densely pruinose, on each side an inferior yellow spot after the legs, and the indication of some ill-defined paler spots above and before them; abdomen tapering to tip, black, densely pruinose ; segments each side on the ventral part with a large, reniforin, somewhat irregular or divided bright-yellow spot ; appendages black, the superiors as long as the two last segments, cylindrical, thicker before the outwardly-bent, pointed tip, beneath with a series of about eleven small teeth; inferior appendage a little shorter, triangular, broad, recurved ; genital parts in the second segment, with the anterior lamina broad, cut straight, a small notch in the middle of the margin; hooks yellow, cylindrical, stouter on tip, which is excavated, the interior part of the excavation forming a produced unguiculated process ; feet black ; wings hyaline, with a blackish spot on the nodus, and a larger blackish band from the base to the triangle after the subcosta, somewhat enlarged along the anal border of hind-wings half-way of the whitish membranula; wings milky-white around the basal band and to the nodes; veins black, the first antecubital yellowish; pterostigma long, oblong, black; ante- cubitals 12 to 14, postcubitals 9 to 10; transversal veins in triangle, 2 to 3; four discoidal areolets, beginning with 5. Male teneral.—The yellow color always brighter and more produced ; dorsum of the thorax brown, with an ill-defined, broad, grayish band each side; on the humeral suture dark-brown; the crista and sinus black; the sides of the thorax paler, with four bright-yellow spots, two inferiors oval, bordered with dark-brown, and two superiors triangular, one between the wings, the other near abdomen ; thorax-beneath pale ; abdomen fulvous, the sutures and margins black; a large black dorsal band, not reaching the base; each side oval, yellow spots on the seg- ments; the two last segments black; abdomen beneath fulvous; the sides and the tip of the segments blackish; feet black; femora brown at base; the anteriors brown beneath ; wings without the milky-white tinge. Female adult.—Pruinose and similar to the adult male, combining in some parts the colors and pattern of the teneral male; labium yellow, : with a narrow black line on the median lobe and the interior margin of the lateral lobes; labrum yellow, the middle part of the margin brown- ish; head yellow ; space between the eyes black, the same color pro- duced a little on the front above and on the sides; vertex brown, black on the sides; eyes behind bright-yellow, two transversal bands and the part near the occiput black ; the head is exactly as in the teneral male, except a larger black band on the labium; dorsum of the thorax prui- nose as in the adult male; the sides less pruinose, with the four yellow spots well defined; abdomen not tapering, the eighth segment enlarged, pruinose, segments 1 to 9 each Side above and beneath with a large, oval-yellow spot; appendages a little longer as the last segment, black, villose, cylindrical, tapering to the outward bent fine tip; lobe be- tween them lutrous, black at base; vulvar lamina exserted, short, notched in the middle, the sides thickened; eggs protruded, small, yellowish ; feet black; wings similar to the male, but without the milky-white tinge, the black band ending before the triangle; 16 ante- cubitals, 11 to 12 posteubitals. Female teneral.—Similar to the teneral male; head similar, black band of the labium broader; body not pruinose; dorsum of the thorax brown, yellow spots on the sides larger, forming two interrupted oblique uacex], ZOOLOGY—PSEUDO-NEUROPTERA AND NEUROPTERA. 585 bands; abdomen similar but not pruinose; wings similar, basal bands rudimentary, covering only the extreme base; 13 antecubitals, 9 post- cubitals. Length of the body, ¢,47 millimeters; ?, 46 millimeters; abdomen, ¢, 30 millimeters; ¢@, 28 millimeters; alar expansion, ¢, 80 milli- meters; ¢, 76-78 millimeters; appendages, ¢, 2; pterostigma, 4 milli- meters. Habitat.—Mexico, the colder region, by Mr. Saussure, a teneral male described in my Synopsis; an adult couple and a teneral female from Yellowstone, Hayden’s expedition, 1872. L. forensis, Hagen, Synop., 154, 9. This species was first described after a male from California in the Ber- lin Museum. Now I have before me a pair from the Yellowstone, and a number of specimens from Victoria, Vancouver Island. This species is similar to L. nodisticta, but surely different. In the adult male, the head is entirely black with the labrum; only the extreme lateral border of the labium, and an indication of the lateral spot of the front, yellowish; the thorax is much more villous, the fine hairs longer and more dense; the dorsum of the thorax pru- inose, but a large, dark-brown band covered with brown hairs on the humeral suture ; the sides brown. beneath, two elongate yellow spots in the middle, and the part above them pale and covered with long fur- — like white hairs, interrupted on the second suture by the brown color expanding upward ; abdomen similar to L. nodisticta, pruinose, the yel- low lateral spots on the dorsum more elongated, visible to the eighth Segment; appendages similar, but the inferior more pointed; genital parts similar, but the anterior lamina forming an ovoid lobe, faintly notched on the tip; feet black; wings analogous, but more intensely colored ; the basal band larger, exceeding the triangle; a large trans- versal black band beginning on the nodus and tapering to the hind margin, indented in the middle; the space between the bands and the pterostigma below the nodus largely milky white, but this color not reaching the apical or hind margin; 16 antecubitals ; postcubitals. Female adult.—Similar to the male; head paler in front, rhinarium, epistoma, brown ; front above with two large, quadrangular, yellow spots, separated by the black middle furrow ; abdomen pruinose, similar ; vul- var lamina larger, opened in the middle; wings alike, the brown bands more or less developed. One younger female from British Columbia has the thorax and abdo- men not pruinose, dark-brown; the wings without milky- white tinge. Length of the body, ¢, 51-44 millimeters; 2°, 48-44 millimeters ; ab- domen, ¢, 34-28 millimeters; ¢, 32-27 millimeters; alar expansion, ¢, 32-74 millimeters; 9, 82-72 millimeters; appendages, ¢, 2; pteros- tigma, 4. Habitat.—California, Berlin Museum; Victoria, Vancouver’s Island, July, Mr. Crotch ; British Columbia, Mr. Crotch ; Yellowstone, Hayden’s expedition, 1871. The latter ones have the smallest dimensions. L. forensis imitates strongly DL. pulchella, a species widely spread and very common everywhere east of the Rocky Mountains; the dark- brown tinge of the tip of all the wings in DZ. pulchella, the smaller size, and other differences, easily separate the two species. A very similar case of imitation is afforded by the two known species of Plathemis, but P. trinaculata inhabits only the vast tracts of land east of the Rocky Mountains; P. subornata, west of them. L. pulchella, Hagen, Synop., 153, 8. Of this well-known species, one male is in the collection of the Hay- 586 GEOLOGICAL SURVEY OF THE TERRITORIES. den expedition of 1871, taken at Ogden, Utah, the only one known to have been found west of the Rocky Mountains. The species is very com- mon in all States east of the Mississippi and in Northern Texas. The southern limit seems to be Mississippi and Georgia. DI. saturata, Hagen, Synop., 152, 4 (partim); Uhler, Proc. Acad. Nat. Sci., Phila., 1857, 88, 4. Stout, reddish-yellow, subvillous ; vertical vesicle narrower at the tip, the sides not emarginated ; abdomen broad, narrower at the tip; geni- tal parts in the second segment, with the hooks excavated transversely on the tip, both ends equally pointed, the interior end black. Body of the female brownish; sutures of the abdomen black; vulvar lamina widely emarginated; feet reddish-yellow, villose; wings of the male hyaline, the anterior margin and the basal half yellowish rufous; basal space and triangle fuscous, the second costal space of the nodus sub- fuscous; veins reddish, the transversals in the first and second costal space bright-yellow; wings of the female hyaline, the costal margin, the basal space, and the triangle colored as in the male; pterostigma narrow, long, fulvous; membranula black; 24 antecubitals, 15 post- cubitals, 5 discoidal areolets; 3 to 4 veins in the triangle. Length of the body, 55 millimeters; alar expansion, 90 millimeters ; pterostigma, 5 millimeters. A Habitat.—Yellowstone (Professor Hayden’s expedition), males and females; Arizona, August 5.. This species was first described by Mr. Ubler after a single mutilated individual from the San Diego trip by Dr. T. H. Webb, perhaps not from California. At the time when I published ~ my Synopsis, I knew only a male from the Berlin Museum, from Mexico, and a male and female communicated by Mr. Saussure, collected at Tampico or Cordova, Mexico. The latter pair belongs, as I now per- ceive, to L. croceipennis. As both species are very similar, I give the differences of the latter. LL. croceipennis, De Selys, Ann. Soc. Belg., 17; Bull., 67, 1.—Lib. sa- turata, Hag., Syn. 152, 4 (partim). Very near and similar in colors to ZL. saturata, but a little smaller in size; the base of the wings in the maleless colored; the basal space and triangle not fuscous; the veins in the two costal spaces reddish; second hooks in the male with the interior pointed end much longer, black; apical inferior lobe of the second segment of the abdomen larger. These differences are taken by comparing the male from California, described in the Synopsis as L. satwrata, with De Selys’s description, and the males of I. saturata from Yellowstone. The following statements are manu- script notes on the specimens, communicated by Mr. Saussure. The male from Tampico has only the alar expansion 80 millimeters; the Lead in front and the feet darker; the wings less yellowish, the yellow color on the costal margin not reaching the nodus, going hardly beyond the triangle, which is not darker than the rest. The female from Cordova is a young cone, paler mesothoracie crest yellow, a yellow band between the wings; appendages yellow ; the eighth segment later- ally dilated; vulvar lamina short, elevated, deeply emarginated, thick- ened on the sides; wings hyaline, costal margin to the principal sector and triangle yellowish. — Habitat.—Cape San Lucas, Lower California, by Xanthus de Vesey ; Tampico, Cordova, Mexico, Mr. Saussure. After De Selys’s Orizaba, Vera Cruz, Mexico, Guatemala, and perhaps Colombia. IT have no doubt about the identity of the male in my collection with ~ f ¥. if , i) SS ee ate ees arta yt, Neh uacex.) ZOOLOGY—PSEUDO-NEUROPTERA AND NEUROPTERA. 587 De Selys’s L. eroceipennis, and the fact that Mr. Uhler at once objected to my former opinion about its identity with his JZ. saturata contirms the statement made above. LI flavida, Hagen, Synop., 156, 15. In wy last report I mentioned a fragment of this species from the Yellowstone, and I find the same statement in my note-book. The frag- ment not being at hand, other specimens would be required to corrobo- rate the habitat. This species is known from Pecos River, Western Texas. LI. composita, Hagen, Hayden’s Report, 1872, 728. I have seen a single female only, which is fully described in the report, and provisionally placed in the genus Mesothemis, near JZ. cor-- rupta. Considering the large size of L. composita, the small, rounded lobe of the prothorax, the enlarged apical segments of the abdomen, and the form of the vulvar lamina, the species should probably be placed in Libellula proper. Habitat.—Y ellowstone. MESOTHEMIS. M. collocata, Hagen, Synop., 171, 3. I named this species after a fragment in very bad condition in the Yellowstone Report. The abdomen of a female was in one bottle and the remaining parts of the insect in another; besides this, the Yellow- stone collection contained some pressed specimens not fitted fer scientific use. I therefore consider my identification somewhat dubious, if I had not received in the mean time two pairs from San Diego, Cal., by Mr. Crotch, which, belonging probably to the same species, confirm my opinion. A full comparison is even now not possible, as the male type ot AZ. collocata is a teneral one, and the two males from San Diego very mature; but the females agree exactly with the rudiment from Yellow- Stone. This species is very near to J. simplicicollis, but different in the black superior appendages of the male; the inferior one is yellow, a character not stated in my Synopsis.. In the younger female, the appendages are yellowish, but the quadrangular, black, dorsal spot on the segments 4 to 10 is wanting; only the sutures and margins of all segments are black. Though convinced of the rights of the species, more material would be needed for a full scientific description. BL. simplicicollis, Hagen, Synop., 170, 1. In my last report I mentioned a single female from Ogden, Utah; at present 1 am more doubtful, the specimen being very imperfect. Prob- ably it belongs to the foregoing species. J. simplicicollis is very com- mon everywhere in the Western Territories east of the Rocky Mount- ains from the northern border to Florida, Cuba, Texas, and Mexico. No specimen is known from parts west of the Rocky Mountains. M. illota, Hagen, Synop., 172, 4. A female in my collection from the Yellowstone, but imperfect, with- out the head, belongs probably to this species, which is common in California from the Gulf of Georgia to Cape Mendocino and San Diego. The L. gilva from Columbia is very similar, perhaps identical. M. corrupta, Hagen, Synop., 171, 3. This species is very common in Texas, California, and is discovered 588 GEOLOGICAL SURVEY OF THE TERRITORIES. in Ilinois by Mr. Walsh. There are a few teneral specimens from the foot-hills of Colorado, June 25 to July 6. _M. longipennis, Hagen, Hayden’s Report, 1872, 728. Habitat.—Yellowstone (C. Thomas). A species common everywhere. DIPLAX. D. atripes, sp.nov. Male.—Reddish-brown, subvillous; labium, labrum, and head reddish ; frontabove near the eyes with a large, blackish, transverse band; vertex reddish, large, inflated, smaller at the tip, with the angles not well marked ; occiput reddish-brown, villous; eyes behind reddish-brown, with transverse blackish spots. ’Prothorax reddish, black beneath, the posterior lobe with very long hairs ; thorax clothed with brownish hairs, reddish-brown, the mesothoracic crest. and the sutures on both sides blackish. Abdomen reddish ; ventral margin of segments 7 to 9, with a large black band ; : appendages reddish, villous, the superiors cylindrical, straight, somewhat thicker for the tip, with about five small teeth; tip shortly- pointed ; the inferior a little shorter, triangular, somewhat smaller toward the apex; the tip bent upward, with two small teeth ; genital parts of the second segment with the hamule black, bifid, the branches not very widely separated, the external stouter, elongately triangular, a little decurved at the tip; the internal shorter, slender, strongly recurved, acute at the apex; genital lobe oblong, rounded at the tip, interiorly inflated; anterior lamina with a small tooth in the middle of the margin; feet black; the anterior femora pale-brown beneath; wings hyaline, with a faintly smoky tinge; the extreme base flavescent ; membranula white; veins reddish- yellow ; pterostigma oblong, reddish ; 7-8 antecubitals ; 7 postcubitals. Female.—Similar to the male, paler ; head yellow; dorsum of the thorax pale-brown, sides yellowish, with three wavy, blackish lines on the sutures ; abdomen luteous ; a large black band on the ventral margin, and another above it not reaching the apex; segments 7-9, with a black dorsal band in the middle; appendages yellowish, cylinarical; vulvar lamina short, truncated; feet as in ¢ ; trochanters yellowish ; in teneral females all femora above in part yellowish; wings as in ¢, the base larger, flavescent; sometimes also the costal border to the pterostigma. Length of the body, ¢, 30-38 millimeters; 2, 31-35 millimeters; alar expansion, ¢, 43-60 ‘millimeters ; 2, 52-58 millimeters; pteros- tigma 13-24 millimeters. 3 Habitat.—Yellowstone; some pairs in copula (Mr. Carpenter). This species is nearly related to D. costifera, but different by the black color of the feet. D. decisa, sp. nov. Similar in shape and colors to D. vicina ; labium luteous; labrum and head in front yellow; front above deeply canaliculated, discolored ; a. large black band before the eyes; antenne black ;) vertex nearly - globular, the anterior angles obtuse, luteous, black around the ocelli; occiput luteous; eyes behind luteous, with two transversal brownish bands; thorax reddish-brown ; on the dorsuma brownish tinge, dilated triangularly to the prothorax ; ‘abdomen reddish-brown; sutures yellow- ish, a black, lateral band dilated behind on the ventral margin of seg- ments 3 to ) and two yellow dorsal spots, nearer to the base; abdomen beneath pale-brown; margin of segments 4 to 7 black; venter black ; - gacex] ZOOLOGY—PSEUDO-NEUROPTERA AND NEUROPTERA. 589 appendages reddish, cylindrical, the apex acute, black, recurved be- neath, in the middle with a stout triangular tooth, with the apical side straight, the basal side oblique, with 6 small teeth; inferior appendage shorter, ending just after the tooth of the superiors, triangular, but the apical half of equal breadth ;. the tip a little excised, nearly bifid; gen- ital parts of the second segment with the hamules long, bent at the base, straight, rounded externally, the apex bifid; the external branch stout, triangularly-pointed ; the internal of equal length, slender, ungui- culated ; anterior lamina excised ; sheath of the penis orbicular, with a longitudinal impressed furrow ; apical lobe of the second segment small, triangularly-pointed ; feet black, all trochanters and the anterior femora beneath reddish- yellow ; wings ‘hyaline, the extreme base flavescent, membranula whitish, alittle cinereous on the margin ; veins reddish, the costa and some transversals near the base yellowish : pterostigma oblong, yellow, darker in the middle; 7 antecubitals; 7 postcubitals; 3 discoidal areolets. Female similar to the male, paler, coloring more luteous; the lateral black bands of the abdomen more enlarged to the tip, no yellow dorsal spots ; appendages yellow, slender, cylindrical, the apex acute; vulvar lamina triangular, bifid, the two branches pointed at tip and a little divergent; the femora of the anterior and intermediate feet yel- lowish beneath. Length of the body, 3, 34 millimeters; ¢, 32 millimeters: alar expansion, ¢, 52 millimeters; 2, 53 millimeters; pterostigma 2 milli- meters. Habitat.—Foot-hills, Colorado; Colorado Mountains, Pacific slope, August 15 to September 6 (Lieutenant Carpenter), several pairs. The species is very similar to D. vicina, but differing in the black feet and the genital parts of both sexes. Some fragments of the male from the Yellowstone are a little larger, but tt probably the same species. D. pallipes, sp. nov. Male.—Very similar to D. decisa, but larger in size and paler in color, differs in the following characters: no transverse, black band before tie eves; vertex yellow in the middle, brownish on each side; the color of the dorsum of the thorax apparently changed by the alcohol, paler (perhaps greenish), with a triangular, brownish band in the middle, and on each side an ill-defined brownish line, not reaching the sinus; sides of the thorax red in the superior half, some ill-defined paler spots above the legs. Abdomen more slender, sutures brown; no black dorsal or ventral bands, except a dorsal brownish mark on the third and base of the second segment; however, these marks could be produced by the decaying process; on the third and fourth segment an indication of two yellow spots before the apex ; venter pale; appendages similar,.but the inferior middle tooth of the superiors with the interior surface not oblique, more perpendicular; the apex of the tooth yellow, with the small tooth more pronounced and black ; genital parts similar, but the external branch of the hamule excavated exteriorly and cut on the tip; internal branch black ; the apical lobe of the second segment narrower, more jointed. Feet more slender, reddish-yellow, a fine black line out- side of the femora, not reaching the base, and a finer and shorter one on the tibia near the black spines ; joints of the tarsi black at the tip. Wings similar, less flavescent at the base ; 8-9 antecubitals; 7-3 post- cubitals. Length of the body, 40 millimeters; alar expansion, 61 millimeters ; pterostigma, 2 millimeters. Habitat.—F oot-hills, Colorado (Lieutenant Carpenter). 590 GEOLOGICAL SURVEY OF THE: TERRITORIES. D. semicineta, Hagen, Synop., 176, 5. A fragment of a female similar to my specimens, but the fuscescent color extending upon the anterior wings as far as on the posterior wings. I never saw similarly-colored Specimens from the region east of the | Rocky Mountains. Habitat.—Foot hills, Colorado (Lieutenant Carpenter). The species is not rare in the States east of the Mississippi as far south as Mary- land. In the last report (1872, p. 728), I noticed from the Yellowstone region D. assimilata, D. scotica, and D. vicina. The first species is, as I now perceive, my J. decisa ; the other two are no more at hand Subfamily CORDULINA. EPITHECA. J. semicircularis, De Selys, Synop. des cordulines, 61, 37. Dark brassy-green ; occiput and labium black ; rhinarium and labium pale-yellowish; on each side of the front a large luteous spot, connected sometimes on the lower edge of the front in a narrow luteous band, inter- rupted in the middle by a small black interval; eyes black behind; thorax dark brassy-green, clothed with long grayish-brown pile before the sinus, sometimes transversally fulvous, sometimes not; the sides with two ill-defined luteous spots ; ‘feet entirely black; abdomen brassy- black, a large fulvous spot on each side of the second segment, a smaller one on the third segment (often wanting in the males) ; “segments 4 to 8 with a small fulvous basal spot on each side (always wanting in the Colorado specimens) ; appendages of the male black, the superiors long subeylindrical, carinate inferiorly and exteriorly ; viewed from above, the basal half is convex, straight, tapering, divergent ; the apical half is bent slightly outward, then inward, subexcavated before the pointed end; viewed laterally, the appendages are curved somewhat . downward, the apex laminate, the lower edge with a small external basal tooth, beyond the middle a rounded lamella, and between them the internal edge produced in form of a larger rounded lamella. Both lamellae, viewed from above, appear as lateral projections; inferior ap- pendage more than half the length of the superiors, triangular, bluntly- pointed, concave below, recurved, the tip minutely uncinate above; appendages of the female long, stout, cylindrical, black; vulvar lamina half the length of the segment, yellowish, quadran cular, somewhat erect 5 apical margin rounded, split in the middle; wings hyaline, or with a yellowish tinge (Vancouver Island specimens) : costa lined with yellow ; extreme base. of the hind-wings subtumose ; membranula blackish-gray, white at the base; antecubitals, 7-8 ; postcubitals, 6-7; triangle in some specimens with a ‘transversal vein in one or both hind- “Wings. Length of the body, 50-46 millimeters ; alar expansion, 80-60 milli- meters; pterostigma, ‘On millimeters. Habitat.—Gulf of Georgia (by Mr. A. Agassiz, the male type described by De Selys), Vancouver Island, in July- (Mr. Crotch) ; pated on win Lake and Arcade River, August 1 to 16; Pacific slope, August 16 to September 6 (Lieutenant Carpenter) ; Ogden, Utah (Mr. C. Thomas). A careful study of the male type in the collection of the museum shows the anterior femora entirely black, not “ presque noiratre,’ as in De Selys’s description. This character is very important as difference from E. forcipata. The words of the description, ‘Je crois distinguer en dessous une sorte de dent subinédiane analogue & ce que Von voit chez E. . / acer] ZOOLOGY—-PSEUDO-NEUROPTERA AND NEUROPTERA. 591 arctica,” are to be struck out, as this appearance was due to some dirt which stuck to the appendages of the typical specimen. The male type and the pair from Vancouver’s Island are larger, most of the Colorado specimens show smaller dimensions, and differ as stated above by the abdomen being black, without fulvous basal spots on segments 4-8; this may be due, perhaps, to the action of the aleobol or of some sub- stance added to the alcohol for the better preservation of the specimens. The difference of E..forcipata is no longer doubtful after the examination of more specimens, but this species is very nearly related, and differs by the labrum having a brownish spot on each side, by the anterior femora being partly fulvous, by the appendages of the male; the vulvar lamina of the female is the same, split on theapex. Having now carefully com- ~ pared FH. arctica of Europe with both species, | am very sure of the spe- cific difference of this species. In £. arctica, the split at the apex and the appendages of the male are different. Subfamily ABSCHNINA. AESCHNA. AY. constricta, Hagen, Synop., 123, 8 (Hayden’s Report, 1872, 727). Habitat.—Yeilowstone, common (C. Thomas); foot-hills, Colorado, a male without head. This species is common everywhere east of the Mississippi from Canada to Maryland and west to Wisconsin and British Columbia. 47, nuliicolor, Hagen, Synop., 121, 4 (Hayden’s Report, 1872, 727). Habitat.—Yellowstone (C. Thomas) ; Vancouver's Island (Mr. Croteh); Upper Missouri, Pecos River, Western Texas, and Cordova, Mexico. A decidedly western species. AY. propingua, Hayden’s Report, 727. Habitat.—Yellowstone, fragments of the male and female ; Colorado plains, June 25 to July 5, female. The specimens are notin good condi- * tion, but I believe them to belong to the species described by Mr. Scudder from the White Mountains, New Hampshire. In the report of 1872, I did mention one female of the 4. eremitica from Yellowstone ; perhaps this female belongs also to 4. propinqua. Subfamily GOMPHINA. OPHIOGOMPHUS. O. severus, Sp. Nov. Greenish-yellow; head and mouth parts greenish-yellow, labium and labrum paler; antenne black; part between the eyes black, forming a transverse black band above the base of the front, excised in the mid- dle; vertex greenish-yellow, flat, the front margin deeply notched, the sides of the vertex cariniform, curved in an exact semicircle around the lateral ocelli; occiput greenish-yellow, straight, fringed with black hairs, a small rounded inflation in the middle of the front side; eyes behind greenish-yellow, with a small, black band along the superior border, beginning near the occiput. Thorax greenish-yellow, an ill- defined, brownish spot on the dorsum each side near the wings; the crest of the sinus not exceeding the bifurcation, black, and an incom- plete blackish band on the humeral suture beginning at the wings. (Three males and two females from Colorado, in alcohol; a single male 4 592 GEOLOGICAL SURVEY OF THE TERRITORIES. from Yellowstone, preserved dry, shows the following pattern): dorsum with a broad black band in the middle, following the sinus above and united with a complete black band on the humeral suture. Mesotho- racic crest from the bifurcation to the prothorax yellow ; a large, ovoid, black spot each side of the dorsum, not confluent with the bands; a black band on the second lateral suture, nearly united by a superior line at the base of the wings with the humeral band; an inferior, incom- plete black band on the first suture, ending at the stigma. Abdomen cylindrical, enlarged at the base, and on the seventh to ninth segments greenish-yellow ; all the segments each side on the apical half with a large blackish band; the bands are interiorly dilated at the tip, and converging (diverging on the first segment) ; venter black on segments 3 to 6, orange on the following; in the Yellowstone male, the bands are broader and confluent on the tip; the yellow part between the bands forming a basal hastiform spot; appendages yellow, the superiors about as long as the last segment, short, parallel, stout, trigonal, exte- riorly rounded, subincurved, pointed on tip, which is bent outward, beneath somewhat thickened before tip, with numerous small black . Spines; inferior appendage a little shorter, triangular, bifid to the base, contiguous, the basal half forming an obtuse elevation, the apex recurved with a small black superior tooth ; genital parts in the second segment with the first hamule forming a lobe interiorly hollowed; the tip witha Semicircular excision, the hind angle of the tip prolonged in a strongly- bent slender black hook; second hamule longer, the tip suddenly nar- rowed, a little recurved, blackish, cut straight; penis with an inferior tooth on second joint, the last one with two long spines; sheath of the penis hollowed out, four-lobed, the two inner lobes cylindrical, divergent, the outer ones large, flat, semicircular ; earlets yellow, large, rounded, on the hind band a series of small, black teeth. The female has the occi- put exactly similar to the male, without any posterior teeth ; append- ages yellow, short, pointed ; vulvar lobe triangular, a little shorter than the segment, bifid to the base, contiguous, indented short before the sSharply-pointed black tip, which is bent outward ; feet yellow, femora au apical superior black band, beginning on the knee, divided anteri- orly ; beneath with numerous very short black spines; tibiz black be- neath and interiorly or on both sides with a black line and long black spines ; tarsi black, all or only the basal joint yellow above ; wings hya- line, veins black; the costa and some transversals yellow; pterostigma oblong, a little dilated in the middle, yellowish, darker in the middle, covering nearly three areolets; 11-12 antecubitals, 7-10 postcubitals ; 2 discoidal areolets; membranula whitish. : Length of the body, 51 millimeters; alar expansion, 64-68 millime- ters; pterostigma, 24 millimeters. Habitat.—Colorado (Mr. James Ridings) ; foot-hills and plains of Col- orado. End of September (Lieutenant Carpenter); Fort Garland, Col- orado, June 27, South Montana and Yellowstone (Mr. C. Thomas). This is the species given in my last report (p. 726) doubtfully as G@. colubrinus. This interesting species is very near O. colubrinus in the appendages and genital parts of the male, but different in the pattern of color on the head and abdomen and the structure of the occiput in both sexes. 0. colubrinus is a species rarely to be found in collections; even the female is not yet described. To prevent doubts about the rights of O. severus, I give here a description of the female of O. colubrinus. I do not pos- sess the male, and my manuscript description of it is still in Europe. O. colubrinus, Hagen, Synop., 101, 7. Female.—Greenish-yellow, marked with black; labium luteous, the wacen.) ZOOLOGY—PSEUDO-NEUROPTERA AND NEUROPTERA. 593 margins clothed with pale-brownish hairs; median lobe with a broad black band on the anterior margin ; jateral lobes and the palpus dusky- brownish ; labrum yellow, with a black shining band on the anterior margin and a narrower one at the base; head yellow; rhinarium with a pale, slender, transverse, black line, interrupted in the middle near the base of the labrum; epistoma with an inferior transverse band, and an- other between the front and the epistoma, a little dilated on the sides, and united near the eyes with the black band above on the base of the front before the antennz; this band is produced a little in the middle and before each antenna; antenne and part between the eyes black; vertex black in front, brownish near the occiput, cariniform, excavated above, front margin rounded, notched in the middle, with a deep, curved impression on each side near the margin; the sides of the vertex curved in a semicirele around the lateral ocelli; occiput yellow, straight, with an anterior furrow in the middle, the border with long, black cilia; each side near the furrow a long, sharp spine, yellow at the base, blackish on tip, divergent, the tip gently recurved inside near the base with asharp tooth, a smaller one after the middle, and a very small one just near the tip; each side behind the eyes just near the occiput and not to be seen in the front view, a stouter black process, cylindrical, somewhat rough | and divided by two transverse furrows, blunt at tip; eyes behind yel- low, with alarge, superior, black band; thorax greenish-yellow, with a large blackish-brown band inthe middle, narrowed toward the sinus, and a large blackish band, not reaching the wings, narrowed above and sepa- rated only by a slender yellow line from a similar band on the humeral suture, which is narrowed beneath; sinus and mesothoracie crest black- ish-brown ; sides of the thorax yellow, with a blackish band on the sec- ond suture, and an incomplete inferior one on the first suture, ending near the stigma; thorax beneath yellowish; abdomen (not in good condition) yellowish, each side with a dorsal blackish-brown band, and between them yellow, hastiform, large spots, not reaching the apex in segments 5 to 6; smaller, and only basal on segments 7 to 9; segment 10 yellowish, the apical margin blackish; the sides of the segments yel- lowish; on segment 2 a large blackish spot; venter brownish ; append- ages wanting; vulvar lobe a little shorter than the segment, triangular, bifid to the base, the lobes rounded, tapering to the tip and convergent, yellowish, the tip. black; feet luteous; femora above brownish; tibiz superiorly paler; femora with shorter, tibiz with longer black spines; wings hyaline, a little smoky; veins black; pterostigma oblong, pale, brown, covering five areolets; 13-14 anticubitals; 11 postcubitals; 2 discoidal areolets, beginning with three. Length of the body, 42 millimeters; alar expansion, 60 millimeters ; pterostigma, 3 millimeters. Habitat.—Portneuf, near Quebec, Canada (Mr. Uhler’s collection). This female agrees well with the description given in the monograph of the Gomphines, p. 77. I figured in the same work (PI. 5, No. 1) the occiput of the male, with two small spines behind the eyes. The figure isthe same in my original drawings now before me, but in the descrip- tion the spines, indeed quite extraordinary for a male, are not mentioned. AS my manuscripts are still in Europe, I am unable to say more about it. To avoid further mistakes occurring, the very closely-related species O. rupinsulensis and O. mainensis, united by the latest monog- rapher, Baron De Selys Longchamps, in 1873 and 1874, 1 prefer to give a full description of both, the more so as both sexes are now betore me. o8Gs 594 GEOLOGICAL SURVEY OF THE TERRITORIES. O. rupinsulensis. “ina Herpetogomphus rupinsulensis, Walsh, Acad. Nat. Sci. Phil., 1862, p. 388, male. Proc. Ent. Soc. Phil., 1863, p. 253. Male.—Greenish-yellow; labium pale-livid (blue, Walsh), black on the anterior margin and the fore half of the side; lateral lobes pale; lab- rum pale, with a fuscous basal spot, but little marked on each side ; head in front greenish-yellow; antennz black, apical border of the first joint pale; part between the eyes and front black; the extreme base of the front between the antennez black; vertex greenish-yellow, caxiniform, excavated above, scarcely emarginate, the sides rounded off at the ends, and a smaller carina in a semicircle around the ocelli; occiput straight, scarcely elevated in the middle, yellow, densely ciliated with long, black hairs; eyes livid behind, paler beneath, with a blackish su- perior spot near the occiput. Thorax greenish-yellow, the meso- thoracic crest black just where it bifurcates, and on the end of the sinus near the wings; a brownish band only indicated on each side near the humeral suture, not reaching the wings; a small brown band on the humeral suture; thorax otherwise immaculate except some brownish spots near the feet to the stigma. The colors of the abdomen not well preserved (pale-brown, clouded with brown, Walsh); on the dorsum of the segments a lanceolate, yellowish spot, two black apical spots, and two small transversal lines in the middle; last segment yellowish, rounded; ventral margins of the segments yellowish 5 venter black, on the four last segments rufous; the abdomen slender, cylindrical, somewhat dilated at the base and much more on segments 7-8 ; appendages greenish-yellow, with long, pale, dense hairs; superi- ors about as long as the last segment, very robust, directed downward. approximate at base, conical, a little bent, obtuse at tip, interiorly with a small basal tooth ; viewed laterally, with an inferior carina, squarely truncate on tip, and on the terminal half below three irregular rows of smail, short, black teeth; inferior about as long and exactly attaining the lower angle of the truncated tips of the superiors, broad, bifid or the apical half, viewed from below and each branch very robus: rounded, divaricate, squarely truncate on tip, viewed laterly strongly incurved, incrassate at base and still more so on tip, which is truncate : genital parts on the second segment with the first hamule black, with a deep, posterior, elliptic excision on tip, the superior angle forming a long, sharp, incurved hook, nearly meeting the opposite angle; the second hamule longer, the basal half thick, pale, cylindrical, the apical half suddenly thinner, black, cylindrical, incurved, and again recurved on tip; sheath of the penis hollowed, four-lobed, the two interior, lobes divergent, short, conical, the outerlobes large, rounded on the margin ; - penis with two small, black, short, incurved spines on tip, and with an inferior tooth on the second joint; earlets yellowish-green, rounded, some small black spines on the inner angle; feet yellowish-green, femora with a broad, brown, anterior band, only near the knee on the four posterior feet, which are more brownish beneath ; tibize black, with a superior yellow band; tarsi black, on the posterior pair yellow in par: above; wings hyaline, slightly flavescent at base; veins black, the costa yellow; pterostigma brown, oblong, surmounting about five cells ; membranula cinereous; antecubitals, 13-14; postcubitals, 9-12; two discoidal areolets. . Hemale-—Similar to the male. Occiput similar, but each side on the border nearer to the eye a short, small, cylindrical, yellow spine, smooth on the tip; a second female has the spine rudimentary; in a third speci- men there is none; behind the eyes, each side, near the occiput, a brown, nacen] ZOOLOGY—-PSEUDO-NEUROPTERA AND NEUROPTERA. 595 robust, conical process, both convergent. Thorax same as in the male; the brown bands on the dorsum darker, nearly confluent with the ante- humeral band in one of the specimens. Abdomen less slender, a little dilated on the tip; colors same as in the male, the dorsal yellow spot on the second segment large; earlets small; appendages yellow, as long as the last segment, conical, sharp, convergent; tubercle between them darker; vulvar lamina yellow, nearly as long as the segment, tri- angular, bifid a little beyond the apical half, the branches contiguous, rounded, tapering toward the tip, which is bent outward, indented just before. Feet and wings as in the ¢; pterostigma larger. Length of the body 3, 52-54 millimeters; 9 51 millimeters; alar ex- pansion, g, 65-68 millimeters; 9, 68 millimeters; pterostigma, g, 3 millimeters; 9, 4 millimeters. Habitat—Rock Island, Wlinois (Mr. Walsh); Upper Wisconsin (Mr. Kennicott); Maine (Dr. Packard and Mr. Uhler). Mr. Walsh saw only one male; the type burned in Chicago was examined by mein 1868, but -I took no notes. The description by Mr. Walsh agrees perfectly with the two males from Wisconsin described by me; Mr. Walsh stated (p. 389) that the male has no tooth on the second joint of the penis, but it certainly exists there, and, as I know that Mr. Walsh used lenses of low power only, he may have overlooked it.. In the third addition to the Synopsis des gomphines, De Selys describes (p. 13) a male from Maine, communicated by Dr. A. 8S. Packard, and erroneously unites with it O. mainensis, as will be seen by the description of this species. O. MAINENSIS. O. mainensis, Walsh, Proceed. Ent. Soe. Phil., 1863, p. 255, female. Matle.—Y ellowish-green, marked with black; labium paler, the margin black; labrum with a narrow, black, front margin; head before yellowish- green; part between the eyes black, and a large basal black band above on the front; antenne black, tip of the first joint pale; vertex black, pale at the base and in the middle, cariniform, excavated above, scarcely emarginate, the sides rounded off at ends, and a smaller carina in a semicircle around the ocelli; occiput greenish-yellow, straight, densely ciliated with long black hairs; eyes behind Hvid, with a black trans- versal superior spot near the occiput; prothorax black, with small yel- lowish spots on the middle and each side; thorax greenish-yellow, with blackish-brown bands; the middle ones narrowed to the wings, sepa- rated by the carina, yellowish to the bitureation; the laterals large and confluent with the antehumeral, only near the wings divided by the paler suture ; margin of the sinus blackish ; sides of the thorax green- ish-yellow, an incomplete, inferior blackish band, ending at the stigma, and a smaller complete one on the second suture; below pale; abdo- men cylindrical, slender, at the base and before the apex dilated, black on all segments, with yellow dorsal spots, enlarged on 1 and 2, basti- form, not reaching the tip on 3. to 5, shorter, more triangular on 6 and 7, short basal and enlarged on tip on 8 and 9, large, transversal, separated from the base on 10; sides of all segments with large, elongated, yel- low spots, divided by the suture, reaching the tip only on segments 2 and 8 to 10; ventral margins of segments. 8-9 black; dorsal articula- tions after the sixth segment yellow; venter black, of the last three segwents fulvous; appendages yellow; clothed with pale hairs; supe- riors as long as the last segment, robust, directed downward, approxi- mate at base, with a basal tooth on the inner edge, conical, sharp on tip; viewed laterally very robust, with a basal inierior carina, the apical half dilated, rounded tillshort betore the sharp-pointed tip, with two series 596 GEOLOGICAL SURVEY OF THE TERRITORIES. of about seven stronger black teeth ; the inferior appendage large, much broader than the superiors and of the same length, the apical half divided by a larger semicircular notch; viewed from below the two branches, large, quadrangular, obliquely truncate, the angles sharp; viewed later- ally incurved, thicker before the recurved tip, the outer angles form- ing a large superior tooth; genital parts on the second segment with the first hamule black, a very long, flat lobe, incurved more on tip; indeed, they are similar to 0. rupinsulensis, the base is broader, and the excision beginning at the base is so large that the superior angle alone exists; second hamule longer, brownish, broad, flat at base, the other part forming a slender, very long lobe, strongly recurved and sud- denly again incurved, the apical part straight; sheath of the penis hol- lowed, ovoid, bifid on tip; the two branches. conical, divergent; penis with two short black spines on tip, and an inferior tooth on od joint; earlets greenish-yellow, rounded, with a series of black spines on the posterior inner angle; feet black ; femora somewhat villous, with very short spines, the four anteriors with a greenish band on the inner side; wings hyaline; veins black; costa yellow; pterostigma oblong, blackish- brown, covering 3 (or 5) cells; 2 discoidal areolets ; 12-13 antecubitals; § posteubitals ; ‘membranula very small, whitish. Female (type described by Mr. Walsh). More adult; the Jabium brownish-black, with a yellowish, basal spot; lateral lobes blackish on the inner border and tip; vertex blackish, with a rounded, yellow, mid- dle spot and a yellow dot on each side; occiput inflated, ciliated above, emarginated behind, and on each side with arounded tubercle; the su- perior edge rounded in the middle with two, but little separated, coni- cal processes, ending in long, sharp, strongly incurved spines, converging so as almost to touch at their extreme black tips; eyes behind black, with a large, inferior, yellow spot, divided in the middle; thorax as in the male, the lateral bands on the dorsum separated from the antehumeral by a narrow, yellowish band, nearly confluent above; an accidental black spot on the left side near the sinus; abdomen stouter, more clav- ate on tip; dorsal spots as in male, none on the three last segments :- appendages about as long as the tenth segment, yellow, conical, sharp; lobe between obtuse, yellow; vulvar lamina yellow, nearly as ‘lone as the segment, oblong, bifid on the apical half, a little broader before an apical exterior indention, the tips sharpened, bent outward; feet as in ¢, the posterior femora with a greenish spot before the tip; wings as in the male; costs black, but near the base the formerly yellow color is visible; pterostigma a little longer, covering 5-6 EMCEE 14-15 antecubitals; 13 postcubitals. Length of eye 46 millimeters; alar expansion, 56-60 millimeters ; pterostigma 2 2—3 millimeters. Habitat. —Maine, by Dr. Packard; I have seen only one pair; the fe- male is the type of Mr. Walsh, in the collection of the Peabody Acad- emy,in Salem, Mass.; the maie, in the collection of Mr. Uhler, Baltimore, Md. Both were collected by Dr. Packard at the same locality , and there is no doubt that both belong to the same species. of thoracic legs, seen from the outside, enlarged 50 diameters. 3.—Hyalella dentata, adult male ; terminal portion of one of the second pair of thoracic legs, seen from the outside, enlarged 50 diameters. 4.—The same, young male; 3.7™" long; terminal portion of the corresponding leg, enlarged 50 diameters. 5.—The same, adult male; maxillipeds, seen from above, enlarged 80 diameters. The hairs are omitted from the palpus on one-side. 6.—The same, adult male; one of the first pair of thoracic legs with its epimeron, seen from the outside, enlarged 50 diameters. : PLATE II. Fig. 7.—Gammarus robustus, female; lateral view, enlarged 5 diam- eters. (The secondary flagellum is figured upon the first instead of the last segment of the peduncle of the anten- nula by a mistake of the engraver.) 8.—The same, male; flagellum of one of the antennz, enlarged 25 diameters. 9.—The same, male; terrainal portion of one of the first pair of thoracic legs, seen from the outside, enlarged 25 diam- "eters. 10.—The same, male; same portion of one of the second pair of thoracic legs, enlarged 25 diameters. 11.—The same, female; terminal portion of one of the first pair of thoracic legs, seen from the outside, enlarged 25 diam- eters. 12.—The same, female; same portion of one of the second pair of thoracic legs, enlarged 25 diameters. 13.—Gammarus limneus, male, from lake near Long’s Peak ; ter- minal portion of one of the first pair of thoracic legs, seen from the outside, enlarged 20 diameters. 14.—The same, male from the same locality; same portion of one of the second pair of thoracic legs, enlarged 20 diam- eters. _ (All the figures drawn by S. I. Smith.) DESCRIPTION OF A LERNAAN CRUSTACEAN (ACHTHERES CAR- PENTERD OBTAINED BY LIEUT. W. L. CARPENTER, IN 1878, IN COLORADO. | By A. S. PackarD, Jr., M. D. CRUSTACEA. Achtheres Carpenteri, n. sp. (Fig. 1.}—Head about half as long as the body, with very minute conical antenne; the antennal region forming a large rounded lobe. The jaws large, finger-shaped. Anchor, or jaw- feet, large, widely separate; the space between ’ them being narrow-oval, and united by the sucker, which is of the general shape of Achtheres. Ab- domen rounded-oval, one-half longer than thick, with indications of three segments; the sutures nearly obsolete, however. HEgg-sacs a nu longer than the abdomen, regularly cylindrical, containing from about forty to sixty eggs, the eggs nearly one-half the diameter of the arms of the anchor-teet. Uniformly pale-white. Length of body without egg-sacs, 0.15 inch ; with egg-sacs, 0.25inch. This should perhaps be regarded as the type of a subgenus of Achtheres, which it resembles more nearly than Lernaocera. f The segments of the abdomen are very faintly cla inteigis Gaya indicated, and in the form of the head and appendages, and their degree of development, it seems intermediate between Achtheres percarum and Oauloxenus stygius, Cope, from Wyandotte Cave, Indiana. Taken from trout, Hast River, August 29 (W. L. Carpenter). SYNOPSIS OF THE FRESH-WATER PHYLLOPOD CRUSTACEA OF NORTH AMERICA. By A. S. PackarD, Jr., M. D That group of Crustacea (crabs, lobster, shrimps, water-fleas) known as Phyllepoda,* is so called from the leaf-like nature of the feet, which are broad, flat, two or three lobed, and adapted for swimming and for purposes of respiration rather than for walking. While the number of feet in the lobster and crabs (Decapoda) is limited to five, in the phyllo- pods the number ranges from ten to sixty, exclusive of the antenne and jaws. The thoracic and abdominal regions are merged into each other, and there is no special distinction in torm of the appendages. One of the most distinctive characters, however, in all except the highest family, Branchipodide, is the large, loose carapace, which is attached by a mus- ele to the head, and elsewhere loosely covers the thorax and the base of the abdomen; in the lower forms (Hstheriade), this carapace becomes enlarged, double, and folded on the side of the compressed body of the animal, protecting it as completely as a clam-shell its occupant; and so striking is the resemblance to the bivalve-shells, especially the small fresh water forms, such as Cyclas, that they are often mistaken for them by collectors of shells. The lower forms, such as Lymnetis, have only ten pairs of swimming- feet, with the body entirely enclosed by the shell, and are not much higher in structure than the water-fleas (Cladocera), such as Dapnia and Sida (Fig. 1), and are scarcely larger, being about a line in length. _ The eggs of the phyllopods are round, and protected by a hard shell, sometimes, as in Limnadia, rough and polygonal. Why the egg-shells are so dense and tough will be seen below, when we speak of the singular mode of life of these animals. The eggs are borne about by the females. In Branchipus and Artemia, they are carried in special egg-sacs, usually long and slender, attached to the base of the abdomen. In Apus, the eggs are few in number, and contained ia an orbicular sac, formed by the adhesion of two of the circular lamelle of the eleventh pair of feet. In the Limnadiade there is no egg-sac, but the eggs are situated loosely on top of the back, under the shell, and held in place by little filaments arising from the legs. ; The young, when hatched, are more or less oval in form, and with but two or three pairs of feet; the first two pairs of these feet representing the antenne of the adult. The young is called a Nauplius, from its resemblance to the young (Nauplius) of the copepodous Crustacea (Hn- tomostraca). Fig. 2a represents the N.uplius of Branchipus (Artemia has a similar larva), and b that of Apus. The young of Limnadia has , but two als of appendages, with an enormous hypostoma, or upper lip. The difference between the sexes is always well marked. In Branchi- pus and Artemia, the second antenne are converted into large- clasping *From the Greek Minos leaf; otc, 7006, foot. 614 GEOLOGICAL SURVEY OF THE TERRITORIES. = appendages, sometimes branched, as in Streptocephalus (Fig. 13), while in the female they are simple and end in a mucronate point. In Apus, the sexual differences consist in the rounded egg-sacs ot the female on the eleventh feet; in the family of which Limnadia is the type, the first pair of swimming-feet in the male end in large, clumsy hooks, adapted as clasping-organs. Now, besides the ordinary, normal mode of reproduction, several genera of the phyllopods are known to reproduce by what is termed by Professor Owen parthenogenesis, or virgin. reproduction; 2. €., the eggs arise from the ovary by a budding process, like the budding of leaves on a tree, through the simple multiplication of cells, without fertiliza- tion by the male spermatic cell. This occurs in several insects, as in the Aphis, the honey-bee, the silk-moth, &c., and in Daphnia, the water- flea, which is closely allied to Sida (Fig. 1), and in other Hntomostraca, A Russian naturalist, Schmankiewitsch, in 1872, discovered a variety of “ Branchipus ” (Artemia) Arietinus, near Odessa. In the summer and autumn of the year before, he noticed that this Artemia changed its form, corresponding to the greater or less saltness of the water. In sum- mer, when the water was most salt, there was a retardation in growth ; and this retardation was the more evident the higher the temperature and the more concentrated the solution of salt. Toward the end of the summer, when heavy rains set in and the temperature decreases, the Artemia becomes larger, loses its red and gray color, and becomes clear and transparent, so that the July generation has important differences from that which appears in November. In order to observe this phe- nomenon carefully, he undertook the artificial breeding of the Artemia in two different ways. In one vessel, he increased the saltness of the water up to 18° Baumé; in another, he reduced the solution to 3°, and thus reared several generations. In both cases, he remarked that each new generation easily lived in such a concentrated solution as the pre- vious generation could scarcely live in. By raising them in so different solutions (18° and 3° Baumé), very differerent forms of Artemia were obtained, which were not to be found in their original pond. “While carrying on these observations, he at the same time proved that a parthenogenetic reproduction exists in Artemia. Each time, both in the great increase of the weak solution as well as in the greatly increased saltness of the water, the females produced new generations, despite the absence of the males. Under these relations of the solu- tions, in warm weather, only females were produced. These females produced in similar breeding-jars only female offspring. Only in water of medium strength were produced males.” As a further illustration of the influence of physico-chemical sienna ings on the organization of these animals I will again quote from the abstract of the remarks of our author. ‘In the salt-pools in the neigh- borhood of Limans (near Odessa), he found in the spring, together with Branchipus (Artemia) feroa, Gr., a very peculiar Artemia, which he thought was undescribed. He thought from certain characters that this species belonged to the higher group of Branchipus. In this form, he observed some strange differences in the structure of the sexual organs, changes which could scarcely be regarded as pathological. Usually, the horns (lower antenne) of the females are small, but in the old females they are clearly elongated, and are very much like ‘the claspers of the males. Still earlier appears a striking change in the structure of the genital organs, when in some, characteristics of the male organs appear. In like man- ner, the sexual organs are clearly changed in the old males ; and, in the sacs in which the outer sexual organs lie, we find a space which is very packarp.] 4 PHYLLOPOD CRUSTACEA OF NORTH AMERICA. 615 similar to the ovisac of the young Branchipus ferox, Gr. In such old males, the spermatic particles are very clearly enlarged. How far these changes could go on, he could not say, since this Branchipus is short-lived. These changes in the sexual organs are especially marked in old indi- viduals; and he further remarks that such misshapen forms often occurred in the salt-pools after heavy rains.” (Siebold and KOlliker’s Zeitschrift, 1872, p. 293.) Such facts as these show how desirable collections in very large num- bers, at different seasons of the year, and from different localities, are for the proper study of these animals. Moreover, they are among the most important facts showing how new generic and specific forms, as well as an unusual mode of a sexual reproduction, arise in consequence of changes in the physical surroundngs of animals. Von Siebold, in his second work on parthenogenesis, has ascertained that Apus also reproduces by this virgin reproduction. Already, in 1856, Siebold had stated his supposition that Apus cancriformis, Lim- nadia gigas, and Polyphemus oculus, in which species no males had been _ observed, presented examples of true parthenogenesis, and were not to be regarded as bud-producing “nurses” in a so-called alternation of generations. Leuckart subsequently expressed the same opinion with regard to the reproduction, independent of males, observed in Daphnia, Apus, aud Limnadia. Ever since that period, Siebold has continually kept an eye upon Apus. In 1858, the males of Apus were discovered by Kozubowski, and Siebold received specimens from various localities, He thus learned to distinguish with perfect facility the two sexes, and was enabled now to convince himself that, as with the Lepidoptera above spoken of, so with Apus, broods occur which are entirely destitute of males, and go on reproducing parthenogenetically, while other broods occur in which both sexes are present. The number of Apus of two species—Apus cancriformis and Apus productus—examined by Siebold amounts actually to some thousands. He received quantities taken from various ponds in Middle Europe (Apus occurs in shallow pools which dry up during parts of the year, and it can be taken in immense quantities), and had the opportunity of studying one pond— that at Gossberg, near Munich—with minuteness, from the year 1864 to the year 1869, inclusive, besides casual examinations of the same pond in 1857 and 1858. Time after time, taking several hundreds of the Apus from the pond, he. never found a single male among them. On one occasion, he had the whole contents of the little pond removed with the greatest care, so as to feel sure that he had obtained every Apus present. He obtained on this occasion 5,796 specimens of Apus, every one of which, being carefully examined, proved to be afemale. At the same time, 2,576 specimens of Branchipus were obtained from the pond, which were, as usual, of both sexes. In those cases where ponds afforded both males and females of Apus, it is remarkable that the proportion of the sexes was very variable. The highest proportion of males appears to be in a case recorded by Sir John Lubbock, who found 33 male and 39 female Apus ,productus in a pond near Rouen; while among 193 specimens of Apus cancriformis, from a locality near Krakou, ouly one male occurred. What is most important about this variation in the proportion of males to females is that in two or three localities, furnish- ing mixed generations of Apus, from which he has received, year aiter year, numbers of specimens, Siebold bas observed an apparent con- stantly augmenting disproportion of males to females, and he is led to the supposition that, in these cases, the males will at last cease altogether, and thus a female generation be produced, which will con- tinue to reproduce itself parthenogenetically, as in the Gossberg and a 616 GEOLOGICAL SURVEY OF THE TERRITORIES. great number of other ponds. This is, however, by no means proved ; and we have no idea at present as to how the males may make their appearance again, or what are the conditions affecting their develop- ment and extinction. It occurred to Siebold that an objection might be urged against parthenogenesis in Apus, in that, although he examined consecutive generations, and found them always female, he: could not be sure that males had not been present before he took his specimens, and had not died and decomposed after having fertilized the females. To meet such an objection, he first made himself thoroughly acquainted. with the male generative organs and the spermatozoa, and secondly with the ovaries and their development. He found the spermatozoa to be motionless like those of other Crustacea, and he never succeeded in detecting any of them in the female genitalia among the specimens belonging to supposed female generations. But he equally failed to find spermatozoa, or a receptacle for them, in the female genitalia of the Specimens of mixed generations, and therefore no conclusion could be drawn trom the observation. The structure and development of the ovum, however, made this observation decisive, since it was found that an egg-shell forms round the ovum in the uterus, and, in the absence of a micropyle, fertilization, if it takes place at all, must be accomplished before this shell is hardened. A further proof of another kind was obtained by experiment. Having removed eggs from females which certainly at the time contained no spermatozoa, Siebold placed them in a small tank, and from these obtained Apus embryos. Others were - reared to maturity from eggs taken in the pond. The relative size of male and female is a question about which there is some interest; differences which have been observed seem to depend on the fact that Apus continues growing as long as the pond in which it lives does not dry up. And hence the eggs which hatch soonest give the largest-sized progeny. In his tabular statements, Siebold gives measurements of the specimens examined by him at different times from various localities. As to the other crustaceans named, which are Artemia salina and Limnadia Hermanni, the occurrence of ‘parthenogenetic broods is infer- red trom the descriptions of other writers whose works are criticised at some length, and also from examination of specimens. Jt seems not impossible, from an observation of Zenker, thatin Artemia salina par- thenogenetic alternate with digenetic broods. In the beginning of the year 1551, this observer found th ee males among one hundred females ; later, in July, the same pond furnished thousands of females, but not one male. -It seems that males and females in this country have occurred in Apus longicaudatus and Apus Lucasanus, but the males occurred in a lot of A. equalis from Kansas. It would appear as if the males from Kansas must be those of A. cequalis; but they were undistinguishable in form from A. Lucasanus from Cape Saint Lucus. Further observations are needed to clear up the matter. More material from the Western States is greatly needed; and as much has been already contributed by Dr. Hayden, it is to be hoped thit the surveying parties sent out under his direction may collect largely of them. This leads to the subject of the geographical distribution of the fresh- water phyllopods of North America. Thus far no species of Apus has been found in the United States east of the Mississippi nor in British America. In Greenland and Arctic America, the Lepidurus glacialis — occurs. In the West Indies, Apus Domingensis occurs at San Domingo. packarp) PHYLLOPOD CRUSTACEA OF NORTH AMERICA. 617 West of the Mississippi, three species are known to inhabit the region east of the Rocky Mountains, and a fourth has occurred on the Pacific slope at Cape Saint Lucas. Of the family Branchipodide, species occur scattered over the whole country, though no Branchipus has yet been discovered in the Pacific States. An Artemia occurs in Mono Lake, California, and the Great Salt Lake. The genus Branchinectes, with one species in Greenland and another in Labrador, is also represented by an interesting form in Colo- rado, at an elevation of 12,500 feet. ‘ Of the family Zimnadiade, species occur scattered over the whole country, east and west of the Rocky Mountains, in British America, and the West Indies. In the Pacific States, but one species (Lstheria Cali- Jornica, Pack.) has occurred, and that is very unlike any eastern species as yet discovered, and closely resembles an Italian species, thus bearing out the aralogy of the Pacific coast fauna to that of Europe. The geological distribution of the fresh-water phyllopods is exceed- ingly interesting. The oldest forms are the Hstherie, which occur as low down as the Devonian formation in Europe, while certain forms in the Mesozoic beds of this country have been described as bivalve mollusks. The genus Apus occurs in European Triassic rocks. The fresh-water strata of Mesozoic and Tertiary age, especially in the West, will undoubt- edly, when thoroughly explored, reveal some of these forms, and the attention of paleontologists and collectors is hereby drawn to them. The habits of these crustaceans are exceedingly interesting from their unusual dependence on physical surroundings. They usually abound in pools and puddles that dry up in warm weather; when the pools are filled, after a series of heavy rains, they suddenly appear. They are very local, rarely met with, but when they do occur, exist in large numbers. This singular appearance after rains, in the beds of pools that have dried up, is due to the wonderful vitality of the eggs, which are sur-— rounded by a dense outer shell, enabling them to resist great changes in temperature, and to be dried up for months without injury. Thus the eggs dropped in the bottom of pools and left there during the hot sum- mer-months, when the pool is dried up, survive the exposure to the sun and the cold of winter to hatch out in the spring. Dr. Brauer, of Vienna, believes, as he has informed me, from certain experiments on Estheria, that the eggs would live and hatch if kept in dry mud for several years. Artemia, which lives in salt-water, can be reared by putting the eggs in fresh water. And here I would ask any one whois so situated to send me a quantity of mud from the banks of Salt Lake, Utah, containing their eggs; the mud taken from the edge of the lake, at any season, must teem with their eggs, and it could be dried and sent east by express. On receiving it, and placing the mud in fresh water, this interesting animal can be reared and studied at leisure. We have seen that these creatures, in one species, at least, like the plant-lice, re- produces parthenogenetically at one season, and by the normal mode at another, and thus some of the most interesting questions in biology may be studied, and perhaps settled by a thorough study of the mode of lite of these interesting creatures. I append a brief synopsis of the fresh-water species of America north of Mexico, beginning with the lowest forms, so that they may be readily identified; and I hope, by drawing the attention of individuals and government surveying parties, espécially in the Far West, to these in- teresting animals, to have their co-operation in the preparation of a monograph of the group. Specimens should be collected by hundreds, as they always occur in great abundance when found at all, and placed in strong alcohol for permanent preservation. 618 GEOLOGICAL SURVEY OF THE TERRITORIES. ’ SYNOPSIS OF THE FRESH-WATER PHYLLOPODA NORTH OF MEXICO. Order PHYLLOPODA. Family 1, ESTHERIADZ.— Body compressed, with from 10 to 27 feet, inclosed in a bivalve-shell. Limnetis.—Shell small, less than two lines in length, round, globose, without lines of growth or umbones; feet-bearing segments from 10 to12. (Fig. 3. L. Gouldii, Baird (Annals and Mag. Nat. Hist., 1862, p. 393).—Shell -with numerous deep punctures scattered over the surface, with the place of insertion of the adductor muscle very smooth and shining. Canada and Massachusetts. LD. gracilicornis,, Pack. (Amer. Journ. Se., 1871).—Differs from ZL. Gouldii in the long, slender, second antenaz, which have about 20 joints. The keel on the front of the head does not reach to the front edge, while in LZ. Gouldit it does; shell of the same form, but much larger than in Z. Gouldit. Length of shell, 0.17 inch; breadth, 0.16 inch. Texas. In fresh-water. pools. LTimnadia.—Shell large, with few (4 or 5) lines of growth, subtriangu- lar or broadly ovate ; animal witha knob-like projection ( ’Haftorgan zi) above the eyes; second antenne with 9 or 10 joints to the flagella; trom 18 to 26 feet. ° Males (only known in an Australian species, Claus.) with large, clumsy hooks on the ends of the first pair of swimming-fect ; body much smaller than in Estheria. I. Americana, Morse (Proc. Bost. Soc. Nat. Hist.), (Fig. 4).—Shell large. broad-oval, with 18 lines of growth, smooth and sbining; allied to Z. gigas of Europe. Length of shell, 0.55 inch. Massachusetts. LI. (Hulimnadia) Agassizii, Pack. (Sixth Rep. Peab. Acad., 1874), (Fig. 5).—Shell narrow-ovate, rather prominent behind the umbones, with 4 lines of grov@th. Animal with 18 feet, and antenne with 9-jointed flagella. Length of shell, 0.25 inch. Penikese Island, Massachusetts. i (Hulimnadia) Texan, Pack. (Amer. Journ. Se., 187 1).—Shell nar- rower than in JL. Agassizii, more oblong, with 5 lines of growth. Animal with 10 joints in the flagella; 18 pairs of teet; and with a larger telson than in L. Agassizii. Length of shel!, 0.27 inch. Texas. “ @uite common in many places in Western Texas. in the early spring. It occurs in muddy pools made after rains, and totally disappears with the first drying of the pools; occurred with Limnetis and Streptocepha- lus.” —(Belfrage.) Limnadella coriacea (Haldeman).—This genus was founded by Girard (Proc. Phil. Acad. N.S., 1854, p. 3) under the name Limnadella Kitei. It was previously described by Haldeman as Limnadia coriacea in the same proceedings (vol. 1, p. 184, 1842). Itis said to have the eyes united into one, with 24 pairs of feet. Shell elliptical; light or dark-brown, spotted with black, three lines in length. Ohio and Fennsylvania. Grube thinks this may possibly be a species of Hstheria. It is very desirable to rediscover this species. Estheria.—Shell oval, more or less globose, (2 yclas-like, with numer- ous lines of growth, amber-colored. Animal without a haftorgan; second antennee with from 11 to 17 joints to the flagella; from 25° to” 27 seg- ments in the body behind the head, and 24 to 28 feet; anterior feet in the males with clumsy hooks. . EH. Californica, Pack. (Sixth Rep. Peab. Acad. Sc., 1874), (Fig. 6).— Shell remarkably thin, so that at first sight it would be mistaken for a Limnadia, subtriangular; umbones very small, situated much nearer BRAD: PHYLLOPOD ‘CRUSTACEA OF NORTH AMERICA. 619 than usual to the anterior edge ; 18 lines of growth, with very fine granu- lations between them. Length, 0.45 inch. California. #. Clarkii, Pack. (Sixth Rep. Peab. Acad. Se., 1874), (Fig. 7).— Shell oblong-oval, thin, about two-thirds as broad as long, with the umbones rather prominent, oblique, situated on the anterior fourth of the shell. About 20 lines of growth. Unusually fine microscopic pune- ‘tures between the lines. Length, 0.45 inch. Male shell narrower, and with rather more prominent umbones than in the female. Animal with 14 joints in antennal flagella; each joint along the middle with 6 or 7 spines above, and 3 or 4 stout hairs beneath; 22 pairs of swimming-feet; tel- son with 2U pairs of unequal spines; claws of male lovg and much curved; telson larger than in the other sex. Ohio, Kentucky, Kansas. May and later. Differs from HL. Caldwelli in the flatter shell, and smaller umboues, while the interstices between the lines are much less coarsely punctate. #. Caldwelli, Baird (Proce. Zool. Soc. London, 1862, p. 148).—Umbones situated almost in the middle third of the shell, broad, and directed a good deal anteriorly ; shell very globose; lines of growth numerous, thickly punctured between them; 0.40 inch. Lake Winnepeg, Grube. HE. Morsei, Pack. (Amer. Journ. Se., 1871).—Shell intermediate in_ form between H. Caldwelli and H. Dunkert, Baird, from Zimapan, Mexico. Much swollen; oblong-oval, pale horn-color, umbones large, promi- nent, larger than in HL. Caldwelli, much less oblique, and situated near the anterior end of the shell. Dorsal margin shorter than in H. Cald- welli, and in front of the umbones, instead of being straight and sud- denly curved downward, is regularly rounded, as in #. Dunkeri. Pune- tures between the lines of growth on an .average, in the middle of the shell, from 5 to 10 in number. Length, 0.50 inch. Six specimens from “ Grindstone Oreek, half-way from Fort Pierre to the Bad Lands,” Dakota. Collected by Dr. Hayden (Mus. Chicago Acad. Se.),—Iowa. H. Belfragei, Pack. (Amer. Journ. Se., 1871), (Fig. 8).—Shell thick, very globose, with the nmbones prominent, situated at the anterior third of the shell; dorsal edge straight behind the umbones, bent rather suddenly downward at two-thirds of the distance from the umbones to the posterior end, the end being full and rounded, 22 lines of growth, between which the shell is coarsely punctuate, from 5 to 8 dots (when placed in a straight line) between the lines. Length, 0.30 inch; flagella with 16 joints; 15 pairs of spines on the telson. Texas. #, Jonesti, Baird (Proc. Zool. Soc. London, 1862, p. 147).—A number of individuals of this species, which do not differ from specimens from Cuba, received from Dr. von Martens, of the Berlin museum, belong to the Chicago Academy, and are marked in Dr. Stimpson’s handwriting “Locality lost.” As no other specimens from the West Indies occur in the collection received from Dr. Stimpson, it indicates that H. Jonesit may possibly occur in the Southern States or Central America. The only ' habitat as yet known is Cuba. Family 2, APoDID@.—Ot large size, with a rounded carapace, partially covering the base of the abdomen, which is elongated, and ends in two long, many-jointed, caudal filaments. About 60 pairs of swimming- feet. Antenne rudimentary. First maxillipeds antenniform. Lepidurus —Body much shorter than in Apus. First maxillipeds shorter, and a long, spatulate, keeled telson, projecting out beyond the insertion of the caudal filaments. LL. glacialis, Kroyer (Fig. 9, enlarged)—A dark-greenish species, which differs from L. productus, Leach, in the distance from the front edge of the carapace to base of hypostoma being nearly one-half less than 620 GEOLOGICAL SURVEY OF THE TERRITORIES. in productus. Supraanal plate with fewer larger teeth. Carapace shorter. Length, exclusive of caudal filaments, 1 inch. Greenland and Peale Krusenstern (Richardson). Apus.—Antenniform maxillipeds long ; telson Squarish. A. equalis, Pack. (Amer. Jour. Sce., 1871), (Fig. 10)— ¢. Carapace longer than in any of the other species; eyes larger. N umber of seg- | ments behind tbe posterior edge of the shield, 23. Length of body (ex- cluding caudal filaments), 1.15 inches. ?. The telson has 5 median spines, and is shorter, while the caudal filaments have more numerous and shorter spines than in A. Newberryi. The under side of the telson is much smoother than in A. longicaudatus, and the outer gill of the first maxilliped is a little longer and more acute. Number of segments beyond the hind edge of carapace, 25, Length of body alone, 1.07 inches. Plains of Rocky Mountains, Kan- sas(?), and Matamoras. Apus Newberryi, Pack (Amer. Journ. Se., 1871).— 9. Differs chiefly from: A. longicaudatus in the shorter maxillipeds, and much longer, smooth telson, with 3 instead of 4 median spines, and in the smooth, finely-spinulated caudal stylets, while the carapace is longer. Number of segments behind the posterior edge of carapace, 29. MENS of body (excluding caudal filaments), 1.78 inches. Utah. Apus Lucasanus, Pack. (Amer. Journ. Sc., 1871).— g. Closely allied to A. longicaudatus. Maxillipeds shorter and smaller; telson longer, with 3 median spines. Anal stylets less spiny than in A. longicaa- datus. Number of segments behind the posterior edge of the carapace, 33. Length of body alone, 0.94 inch. Q. Carapace longer than in.é, and caudal filaments not so heavily spined. Numberof segments behind posterior edge of shield,29. Length of body alone, 0.80 inch. Cape Saint Lucas. Males from Kansas. Apus longicaudatus, Leconte, g and @ (Annals N. Y. Lyceum, IV 155, 1846). —In this species, the body is larger and carapace is shorter than in any of the others. James's A. obtusatus (Long’s expedition) is probably this species. The 9 differs from males in the shield being longer, with 28 segments beyond the end of the shield, and the under side of the telson is smoother, but above, asin ¢; ovisac, 0.10 inch in diameter. Length of body, 1.50 inches; of carapace, 0.60 inch. The caudal filaments are smallerand more coarsely spined than usual. Rocky Mount- ains, near Long’s Peak (Mus. Yale Coll.); Texas. Pools near Yellow- . stone River, Dr. Hayden. “ Found in immense numbers in a small shallow lake on the high plateau between Lodgepole Creek A. Crow Creek, northeast of Long’ s Peak.”—(Leconte.) Fatnily BRANCHIPODID.&.—Body long and slender, with no carapace; eyes stalked ; second pair of antennze adapted for ‘clasping ; 11 pairs of branchial (respiratory) feet. Female with a large egg-pouch attached at the base of the abdomen. Prof. A. HE. Verrill, in his valuable “Observations on the Phyllopod Crustacea of the Family Branchi- pide ” (Proc. Amer. Assoc. Adv. Se., July, 1870), has given the characters of the genera and species, and I give abstracts of his diagnoses of the generic and specific characters, with the addition, however, of descriptions of Streptocephalus Texensis and Branchinectes Coloradensis, which have been described since the publication of his paper. Artemia. Clasping organs (second antenne) threejointed; egg-sac short, broad ; living in saline or alkaline waters. Artemia gracilis, Verrill (Fig. 1!, enlarged).—Body slender; in the tale about 0.3 inch long ; in the female, 0.4 inch. Claspers of the male relatively long and powerful ; first joint thickened, with a distinct angle packanp.] PHYLLOPOD CRUSTACEA OF NORTH AMERICA. 621 at the articulation on the outside, and a short, rounded, nearly semi- circular process on the inside near the base, about its own diameter from the base; second joint broad, flattened, continuous with the third joint, strongly curved ; outline nearly regularly convex on the outside, until near the middle it suddenly bends inward, torming an obtuse angle, beyond which the outline is concave to the last articulation, where it becomes again convex, forming on the last joint a slight, rounded angle ; the inner edge is nearly straight, or but slightly concave, to the last articulation, where there is a slight but distinct angle; last joint tri- angular, longer than broad, tapering to the acute, “slightly: -excurved point. Ovigerous pouch of ‘the female, when seen from below, flask- shaped. ‘In tubs of salt-water on railroad-bridges, New Haven, Conn., and Boston.”—(Verrill.) A. Monica, Verrill.—“‘A little larger and stouter than A. gracilis. Male- claspers relatively stouter; the hook, or outer two joints, being much broader, more triangular, and less ‘elongated. Caudal appendages smaller, and sides of egg. pouch less angulated on the sides than in A. gracilis.” Mono Lake, California. A. fertilis, Verrill—* Larger than eitber of the others, some of the speci- mens being three-quarters of an inch in length. Male- claspers stout, with the second joint broader and more triangular than in either of the preceding species. Great Salt Lake, Utah.”—(Verrill.) Branchinecta.—Form rather slender, with the median appendages longest, so as to somewhat resemble Artemia in outline, but larger. Male with rather slender, rounded, two jointed claspers. HEgg-pouch much elongated. B. arctica, Verrill.—‘ Male-claspers rather long and slender; basal joint but little swollen, elongated, regularly curved, with a small tooth or prominent angle at the articulation on the inside, and on the inner side a row of numerous small, distinct, sharp teeth, extending from the articulation about half-way to the base, and arran ged somew hatobliquely ; second joint slender, regularly curved, tapering to a blunt point, the inner edge minutely serrulate. Egg-pouch of temale much elongated, slender, subceylindrical.”—(Verrill.) In a small pool, north shore of Ham- ilton Bay, or Invuctoke Inlet, Northern Labrador (Packard.) B. Grenlandica, Verrill.—‘A little stouter than B. arctica; the largest male 17 millimeters long. Claspers similar to those of B. arctica, but more elongated; the basal joint less curved, and the second joint longer, * less regularly curved, tapering more quickly at base, and, consequeutly more attenuated beyond the middle, with more slender tips, which are nearly straight. The tooth on the inside of the first joint is rather more prominent, but the row of teeth along the inside is similar. Caudal appendages stouter, tapering more rapidly. Greenland.”—(Verrill.) B. Coloradensis, Pack. (Fig. 12, male, female, and head of female).— Differs from 6. Grenlandica, its nearest ally, in the basal joint of the claspers being less curved, slightly shorter, this and the second joint being entirely unarmed. The second joint is sinuous, not tapering, swollen, avd bent in slightly at the tip when seen in outline, but seen ‘in front broad and flat, subspatulate. Caudal appendages ratber stout, broader at base, and not contracting as in B. Grenlandica. Length, 0.57 inch. Colorado, one 9 from a ‘*‘ pond on a mountain near Twin Lake Creek, Colorado; elevation, 12,500 feet.”—(Hayden’s Survey of _ Colorado, 1873; collected by Lieut. W. L. Carpenter, U.S. A.) About a hundred males, and females, with eggs, Colorado, Dr. Viele (Mus. Comp. Zool. Cambridge), No date. Jt will be interesting to determine whether these three forms are a 622 GEOLOGICAL SURVEY OF THE TERRITORIES. really of specific value. For this purpose, large numbers of specimens from different localities at different dates are necessary. After the ob- servations made at Odessa on the wonderful degree of variation in Arte- mia at different seasons of the year and density of the water, we are led to think, from the fact that the females of the above three species of Branchinectes are almost undistinguishable, that the forms are possibly conspecific, and the differences which have been indicated are the result of climatic and other physical causes. At present, however, it will be, perhaps, wisest to regard them as distinct. Eubranchipus, Verrill.— ‘Body robust; male with large head and very stout claspers; first joint of clasper much swollen, capable of retracting the basal portion of the second joint into their cavity ; second joint stout at base, in the typical species with a large tooth on the inside, the outer portion tapering, rather obtuse. Front of head between the claspers bears two thin, flat, tapering appendages, serrated on the edges and transversely striated or jointed. Caudal appendages long. Egg-pouch short and thick.”—(Verrill.) E. vernalis, Verrill.—‘Claspers very large and strong; the basal joint much swollen: second joint long, broad, with an angle on the outside, from which it rapidly narrows -by strongly concave outlines on each edge, bearing at the constricted portion, not far from the base, a large, strong, very prominent, crooked, bluntly-pointed tooth, which is directed inward and backward. Massachusetts and New Haven, Conn. Very early in spring in quiet pools.”—(Verrill.) Streptocephalus, Baird.—Male-claspers long, three-jointed, tortuous; the terminal joint subdivided more or less into two or more branches, or bearing slender appendages. Male organs long, slender. Egg-pouch elongated or conical. s. Texanus, Pack. (Amer. Journ. Se., 1871), (Fig. 13, male enlarged).— Male differs from 8S. similis, Baird, from San Domingo, in the longer branch of the inferior antennz being much longer and slenderer at tip, while the shorter branch is much narrower. Length of male, 0.65 inch; female 0.55 inch. Texas, in pools, in summer, formed by the summer- rains, which had dried up early in the season; and also in April.— (Belirage.) Phyllopods. Plate I. ‘1Sida 2 a. Nauplius of Branchipus. 2b. Nauplius of Apus. hy | Uae i 4 t { i 4 Phyllopods. Plate ITI. (Sal ed 3. Limnetis. 5. Limnadia Agassizii. 6. Estheria californica. 4. Limnadia americana. WOME he Q et Scesaner bee av 23 | ana on) ee eer femal « mary Phyllopods. Plate III. 7. Estheria Clarkii. 9. Lepidurus glacialis. 10. Apus equalis. 8. Estheria Balfragei. aa: y a yWilers | wee DER aA Y: Plate IV. Phylilopods. Branchinectes Coloradensis Pack. C \ 13. Streptocephalus texanus. 12. Branchipus coloradoensis. 11. Artemia gracilis. es a ~ - i} @ feat 333 4 LIST OF LEECHES COLLECTED BY HAYDEN’S EXPEDITION, 1878. By A. E. VERRILL. Nephelis lateralis Verrill (Say, sp.) A plain, dark brown variety, Clear Lake, Col. (Lieutenant Carpenter). Clepsine ornata Verrill, var. b. In this large variety, the back is covered with numerous prominent papille, arranged i in transverse rows. The two ocelli are united into one. Clear Lake, Col. (Lieutenant Carpenter). Aulastomum lacustre Leidy, var. fuliginosum Verrill. In this variety, the color is nearly uniform dark brown. From a lake, elevated 9,000 feet, near Long’s Peak (Lieutenant Carpenter). It occurs also in pools near New Haven, Connecticut. , Nephelopsis obscura Verrill, dark variety. The preserved specimens from this locality are dark olive, with black- ish mottlings. Found with the Aulastomum, from a lake, at 9,000 feet elevation, near Long’s Peak, (Carpenter.) Nephelis quadristriata Verrill. One specimen is nearly uniform obscure dark brown; another has two broad, blackish, dorsal bands, with a narrow, light, median stripe. Little and Big Thompson, Estes Park, Col. Jitensenena Carpenter). Clepsine pallida Verrill, var. b. The back is nea with narrow, dark stripes; six Gistinet ocelli. Occurred with the two preceding. Clepsine pallida Verrill. The preserved specimens are brownish, with six small ocelli. Colorado (Lieutenant Carpenter). LIST OF TERRESTRIAL MOLLUSKS COLLECTED BY LIEUT. W. L. CARPENTER, U. S. A., FOR THE UNITED STATES GEOLOGICAL SURVEY OF COLORADO, 1873. By WILLiaAmM G. BINNEY. HELICIDA. Helix pulchella, Miill., Este’s Park, Vitrina Pfeifferi, N CWC, head of Gunnison River. Patula striatella, Anth., Este’s Park. Succinea lineata, W. G. B., Este’s Park. Patula Cooperi, W. G. B., Grand River. Patula strigosa, Lea., Grand River. ae be At Dee eth i As “8 wager: fee ae : h ] uw Sy | a a Pye) a5 $3 eh Ha hee ‘a Yes i hie ‘6 ms BB a He ho me :. Kk Ah) & ial hie us ‘ Je a Ja el ge GEOGRAPHY AND TOPOGRAPHY. 40 GS See he ne abuse eds Sg, . id i ) y 7 BEPARTMEKT OF THE Inte Rion J. 8. Geological and Orographteal Survey of the Ternilerkes | BY. Hayden U.S. Geologist in Charge SKETCH, showing the Primary and Secondary, TRIANGULATION or 1875 The Primary Triangulation fn rep resented by the Aeary lines; the Seeandary by light Lines, and 1nebsere ed angles by broken liner Saule ot miles Pomey Thawte by As 7 came. Bevemary Trhasyation oy Atason, MEY QUOT wt an maoen sz SS = == SKETCH OF THE METHODS OF SURVEY IN THE GEOGRAPH- ICAL DEPARTMENT. By James T. GARDNER, GEOGRAPHER. WASHINGTON, July 18, 1874. Sir: I have the honor to inclose a sketch of the methods upon which the work is based in the geographical department of this survey, and also the results of my investigations to determine the true elevation of Denver; regretting that the latter has occupied so much time that full reports of other branches of my work must be delayed till next year. Very respectfully, JAS. T. GARDNER, Geographer. F. VY. HAYDEN, Geologist-in-Charge, U.S. Geological and Geographical Survey of the Territories. The horizontal measurements of this survey are made by a connected system of large and small triangles, developed from a measured base near Denver. I have endeavored to bring the trigonometric work to such a grade of accuracy that its errors will not be appreciable within the limits of the Territory on maps of a scale of four miles to one inch. With this purpose, the primary triangulation was expanded by me from the Denver base, four miles of which are on the track of the K. P. R. R. and two more are over very level ground. The termini are, however, so much higher than the central part that the line of sight between them is never less than 20 feet above the surface and generally 40 feet. Its length was twice measured with a steel tape, compared before and after meas- urement with the United States Coast-Survey standard. The tape was under 20 pounds strain, and temperature-observations were taken every five minutes. The profile was determined by leveling, and results of the measurements corrected for level and temperature. Triangular pyra- mids 30 feet high were erected at the stations on the plains, by which the triangles were expanded to the mountains, where roughly-built stone monuments were used to sight at, except in the very long lines, where they became invisible, and the exact summit of the peak was taken. The angles were measured with an 8-inch circle graduated to 10”, and reading to 5”, constructed by Wm. Wiirdemann for the United States Coast-Survey. The measurements were generally repeated six times on different parts of the circle. The plan of the triangulation is shown on the accompanying map. Azimuths were observed at five of the principal trigonometric stations by repeated observations between Polaris and an illuminated signal on one of the lines of the triangulation. 628 GEOLOGICAL SURVEY OF THE TERRITORIES. At Denver and Colorado Springs, the triangles are connected with very accurate astronomical stations, located for us by the kind co-opera- tion of the United States Coast-Survey. Geodetic latitudes and longi- tudes of forty-eight stations were reduced trigonometrically from Den- ver, and plotted on a projection. From these points, the secondary triangulation and topography was plotted with protractors by the topog- raphers. The accuracy of the triangulation is determined by the clos- ure of the triangles, whose observed angles should sum up to 180° plus the spherical excess. The forty-seven triangles, completed in 1873 and used in the final adjustment of the scheme, have a mean error of closure of 10.3. During the season of 1874, a check-base will be measured in the San Luis Valley, and we shall then be able to judge more closely of the probable errors of measurement by this triangulation. At pres- ent it appears as if they would not exceed two feet per mile. Twelve thousand square miles were completed last summer, and more than twice that amount partially finished. The secondary triangulation is done by the topographers with the eradienter, whose circle is small, but its telescope powerful. The error of closure of these triangles is about 2’. As they rest for their bases upon the primary triangulation, the errors do not accumulate over any large area. The topography is sketched from the trigonometric sta- tions, and the principal points of the sketch located by triangulation. The important roads are meandered. The magnetic needle is not used for angular measurement, except for minor details. The vertical measurements of the survey are based on determinations of the height of the trigonometric stations above Denver on the follow- ing plan: The D. & 8. P. R. R. had run a line of levels from Denver, whose elevation is about 5,000 feet, up to Fairplay, at about 10,000 feet, and I had these levels extended at our expense to the summit of Mount Lincoln, about 14,090 feet high. These points are about sixty miles west of Den- ver. On Mount Lincoln and at Fairplay we established baremetric sta- tions, and at Denver the station of the United States signal-office was used for reference. Ninety miles to the south, at Canon City, on the D. & R. G. R. W., we had another barometric station at an elevation of about 5,000 feet. The heights of the base-barometers above Denver being thus known by railroad-levels, the surveying-parties, using mereu- rial barometers (Green’s mountain-barometer) observed at their stations and camps synchronously with the observations at the permanent sta- - tions. The height of any point where observations were taken was deter- mined by referring them to the permanent station nearest in altitude. From the trigonometric stations, angles of elevation and depression were taken to a great number of points to assist the topographer in sketching the contours of the ground. These are, of course, referred to the elevation of the trigonometric station, as determined barometrically. As it was impossible to proceed with our final maps until the elevation of Denver was known, I have undertaken to put together into connected chains all the various lines of railroad-levels that unite Denver with the sea. It has been a labor of many months. The details and results of the investigation are given in a separate report. THE ELEVATIONS OF CERTAIN DATUM-POINTS ON THE GREAT LAKES AND RIVERS AND IN THE ROCKY MOUNTAINS, By JAMES T. GARDNER, GEOGRAPHER. INTRODUCTION. As the field of labor of the United States geological and geographical surveys of the Territories now les in Colorado, the following work was undertaken for the purpose of determining the elevation of Denver, which is at present the base from which all altitudes in the Territory. are measured. The height of Denver above the sea had been vari- ously reported at from 5,043 feet to 5,303 feet, and the spirit-level lines of the K. P. and U. P. R. R.s seemed to differ nearly 200 feet. Believing that any such large discrepancies between spirit-level lines must be due to false reports and errors in joining the different links of these long chains to the sea, I determined to reconstruct all pos- sible lines of levels from the ocean to the Rocky Mountains, using only official reports by engineers, and checking them by personal examina- tion of their note-books and working profiles wherever practicable. For this purpose I visited the railroad-engineer offices at Denver, Omaha, Lawrence, Kansas City, Saint Louis, Chicago, Cleveland, New York, and Philadelphia, examining not only the completed profiles and the original notes from which they were made, but making, also, such corrections as then seemed necessary to unite the lines of different companies. Several of the most important profiles were lost in the Chicago fire, and of one of these, that of the C., A., & St. L. R. B., no record is left. Profiles of the C. & N. W. and of the C., R.1., & P. B. Ris had been sent to the geological survey of lowa, and had been published; these have now to be used instead of the originals. For many years, various Departments in Washington have been gathering railroad and canal profiles. Mr. Nicholson, the topographer ot the Post-Office Department, deserves especial mention for his long- continued activity in this important work under the Smithsonian Insti- tution. Lately, the office of the Chief Signal-Officer of the United States Army has compiled all of this material, with a large collection of their own from original sources, and carefully arranged and indexed it. In the 1871 and 1872 reports of the Chief Signal-Officer, Gen. Albert J. Myer, he speaks of Lieut. Henry Jackson, acting signal-officer and assistant, as having vigorously prosecuted this department of the work. The collection comprises over one thousand profiles and reports from original sources; and efforts are being made to render it so complete, as to the profiles and their connections, that the elevation of every town on railroad or canal shall be well determined. The civil engineers of this country cannot render a greater service to geographical science than to send to the United States Signal-Office copies of railroad and canal profiles. Some of the most important problems in the meteor- ology of the country are dependent for their solution upon our exact knowledge of the elevations of the observing-stations; and these must 630 GEOLOGICAL SURVEY OF THE TERRITORIES. be determined independently of the barometer. The elevations should be known to within five feet to satisfy the present needs of meteor- ology. The use of this large and admirably-arranged collection was kindly offered me, and to its assistance I am largely indebted for the complete- ness of this investigation. The principal difficulties encountered in the present work were: the’ discrepancies between the different official reports of the profiles of the same railroad or canal; the difficulty of finding the points referred to at the ends of the profiles; the difficulty of connecting them with the mean surface of the ocean; and the clerical errors or mistakes in figures evidently due to.copying. The differences between the reports of the profile of a railroad or canal seem to arise from want of care in computing from the level-notes, and from the fact that they are actually reports of different levelings which do not agree. Generally, a preliminary line of levels is first run over the whole line of the railroad, and bench-marks established; then, when construction is commenced, the different divisions of the line each take one of these bench-marks as the datum for their levels, and build their part of the work from this point. Thus, the line as a whole is really built from many separate datum-planes. Where the different divisions join, they connect their levels so that the relative height of the diiferent datum-planes may be calculated, and all may be reduced to one base. The notes of these connections are generally correct; but, in the first calculations of them, many errors almost always occur, incident upon the hurry and confusion of closing the work and dismissing the engineers for the sake of economy. After the railroad is running, and the chief engineer has leisure to examine the records of his office, errors are found in the calculations of his profiles, and the whole is reviewed and a new profile constructed. It often happens that, after a number of years, either a part or the whole of line is releveled, and a new profile is the result. Among the profiles which I have examined are vepresen tates of all these classes: First. Profiles of preliminary lines of survey. Second. Profiles from first calculation of constructed lines. Third. Profiles of final calculation of constructed lines. Fourth. Profiles of final releveling of constructed lines. Fifth. Profiles made up in the offices by mixing the results of two or more of the above classes. It is evident that these classes must differ very much in accuracy; and necessarily the first step in this examination was to determine upon methods of testing the profiles so as to fix their proper relative weights. This was a very complicated and difficult process on account of the num- ber of factors to be considered. Some of the principles may, however, be stated. If two points were connected by several independent lines of railroad or canal, the agreement of these lines as to the difference of altitude of the termini was considered one of the best tests of accuracy. If one of these lines was a canal which had been releveled many times, and the termini carefully connected with the other lines, and of which we had a final official report, this was taken as true and used as a standard of comparison for the accuracy of the other lines. If the lines were all canal-levels, their relative weight was determined by the number of times they had been releveled, the recertness of the work, the recentness of the official report, and its detailed character. CA aE GEOGRAPHY—ELEVATION OF DATUM-POINTS. 631 If the lines were all railroad-levels, the following points were consid- ered as favorable to the character of any line or connection of lines: First. That the official reports should be recent and detailed. Second. That they should be reports of the final computation of the construction-levels, or a releveling of the completed line, or, best of all, that we should have both of these reports agreeing closely. Third. That there should be few connections of lines formerly inde- pendent to make up the present through-line. Fourth. That, where the line was made up by joining several parts formerly independent, the connection between them should not be open to any doubt. If, of several lines between two points, one disagreed largely from the others of apparent equal weight, it was considered as probably in error. If several railroads, rnnning from a common point, cross an important river, the fall of the stream was determined by the very best lines, and those were rejected which made it run up hill or gave an improbable fall. If several parallel railroads were cut by a cross-line, well connected, their agreement upon this common line was considered as an important test. If several lines of levels between two points start from a common datum or directrix, and end also at a common datum, the connection for comparison is far more reliable than when the ends of the lines merely came into the same city, and then have to be joined by connecting the depots by city-levels. The results of the application of these standards of accuracy showed that recent official reports of the final computation of the construction- levels were generally reliable so far as any one line is concerned. The Pa. R. R. may be given as one of the best examples. It has been recently releveled, and though there was a discrepancy between the new and old elevations of Pittsburgh of 11 feet, it was found on a third. leveling of a part of the line that this was due to erroneous connection of two leveling-parties, and all occurred at one point. And now, when a final computation of the old construction-levels, aud of the new and corrected line, is made, the elevation of Pittsburgh by the new line is within a foot of the old. Great credit is due to Mr. Wilson, the consult- ing engineer of this road, for the interest he has taken in investigating the discrepancies of the Pa. R. R. profiles, and through his exertions we have at last a correct report of the profile of that important railroad so many years after the levels were run. The profiles that seemed from their dates to be first calculations of constructed lines were often found unreliable, and do not generally agree with the final calculation of the levels when we have reports of both. The profiles of preliminary lines of survey were, of course, found very unreliable. The elevations of Cai- ro, Lil., and Columbus, Ky., have hitherto rested on a preliminary survey of the M. & O. Rt. R. from Mobile Bay, and seem to be 10 to 15 feet below the better determinations. The worst of all the profiles, and the most perplexing to the geographer, are those made up in the offices of some of the railroads by putting together data from old and new printed reports and from all the manu- - script profiles in the office, and treating them as if the same datum of levels was referred to in all these sources of information. The mix- ture thus produced generally defies the most ingenious power of anal- ysis in the searcher after truth. In general, [ am satisfied that the important errors in our railroad and 632 GEOLOGICAL SURVEY OF THE TERRITORIES. canal profiles are not so much due to imperfect instrumental work as to hasty computation and careless combination of the results. The difficulties of making connection between the end of one profile and the beginning of another have been very great. Most cities have now a datum or base-point from which all the city-levels date, often called the city directrix. The United States Signal-Office has taken great pains to get reports from most of the city-engineers of the heights of the railroad-depots above these city-directrices; but the difficulties of using this connection between railroads is that in many cases the present depots are not the ones referred to on the profiles of the roads; and even when the present depots are the same as the old ones, the grade at the depot has been changed since the railroad-profile was made, and no note of the present orade made on the profile. This seems to be the case in Chicago, where the railroad-profiles almost all indicate a lower grade for the depots than those reported by the city-engineer. By visiting the ground, and making connections with old benches, I have gotten rid of many of these errors, and, fortunately, in many cities the railroad-engineers have connected their datum with that of the city. If the engineers of this country will adopt this as a rule, the value of their work for general and scientific purposes will be very much increased. The railroad-lines from Philadelphia, and the railroad and canal lines from Albany, had reported the elevations along their lines above tides of various stages at these points, and the G. T. BR. W. of Ca. had reported their elevations as referred to tide at Three Rivers, the head of tide-water in the Saint Lawrence. These datum-points differ from each other, and from the mean surface of the ocean, which is the only proper plane of reference for our elevations. The errors due to this cause have entered into all previous reports of elevations in Pennsylvania and the regions about the great lakes. By the assistance of the United States Coast Survey, and of Mr. Smedley, city engineer and surveyor of Phil- adelphia, the datum-planes of the Erie Canal and N. Y. C. BR. R. levels and of the Pa. R. R. have been connected with the mean surface of the ocean. Important changes are made as the result of this investigation. The elevation of the great lakes and surrounding country is.found to be about 9 feet more than previously reported by the State geologist of Ohio, and that of Saint Louis about 23 feet higher than reported by Humphreys and Abbot. While Kansas City, and all the surrounding | country for many hundred miles south and west, has heretofore been reported more than 100 feet too low, Omaha is raised about 31 feet, and Indianapolis about 100 feet. The fall of the Mississippi above Memphis, and of the Ohio, and of the Missouri River, is also changed. The amounts of these changes are so great, and the accuracy of the results of such importance to science and to our work of internal improvements, that I publish the evidence upon which they rest, and a statement of the evidence upon which previous reports were made where such could be found. The checking at Denver of the levels brought through by the U. P. and D. P. R. R., and by the K. P. R. BR. is so close that I believe the error of elevation of this point cannot exceed 10 teet, exclusive of that dune to deflection of the plumb-line by attraction of mountain-masses. The result by the K. P. R. BR. is 5198.97; and by the U. P. and D. P. R. Rs, 5194.20 feet above mean sea. My determinations of the elevation of Ogden, above the Atlantic Ocean, by the U. P. R. R., and above the Pacitic Ocean, by the C. P. BR. R., differ only 25 feet. When it is con- carpyern] 4 GEOGRAPHY—-ELEVATION OF DATUM-POINTS. 633 sidered that the line of levels from the Atlantic to Ogden, Utah, is about two thousand miles long, this discrepancy is small. It is not improba- ble that a large part of this error lies between Cheyenne and Ogden, where the work on the U.P. R.R. was driven at an unprecedented. speed, and where the line lies over mountains, The accompanying map shows the lines of levels that have entered into this discussion. | Discussion of evidence of the altitudes of various points in the United States and Canada. THE ELEVATION OF LAKE ONTARIO. 82 | A AS Teet. Various datum-planes. | #2. . 2S Pela £588 Sato >) ae a First determination. Yean tide at Albany, by United States Coast Survey 4.84 | Above mean tide west 4, 84 | leveling. end of Highteenth street, New York. 7oae surface of Lake Ontario, by report of final level- 245.15 | Above M.T., Albany ..-.|.......... ings of Erie Canal, (see profiles accompanying an- ‘nual report of State engineer and surveyor of New | York, January 1, 1268, by J. PB. Goodsell.) Mean surtace of ECM OTTA TI ORCC MNES MEN de rym meant en) (bab AREA a Alan's on deine ae c's eke eh CRY 249, 99 Second determination. fean tide in St. Lawrence River at Three Rivers, 6.7%") Above MAH. I: at'Port- |----2-+-6- datum of levels of G. T. R. W. of Canada. | Jand, Me bUBLAC OO Mako ONUILIO see = aie caries aie ate srisie sists lessee sine 935.00 | Above M. ‘'.,- Three |.......... ; Rivers. 101) Soha oc coe SOS SSE4ESS POOSE Elan Sarre ener cereerae 241,77 | Above M.H.T., Portland).......... [These figures are from a report of the chief engineer of the G. T. R. W. of Canada, dated March, 1872. ean high-tide at Portland, Me. , by United States Coast 45 5)\| Above Me I. Portland ss|"=seseeses Survey report. ba OLE AKe) ONGALI OMe sereceeee eee ee rae eerie etal [emis eeiseick llc es eleicisieistec alsayve mjetmisete rere 246, 27 Final results. Surface of Lake Ontario: : HTS berniin atl Oly sees se aetenee eateoioe oe seers ss ens|| sbes ae sais |selnecwtee cscs. smectemert 249, 99 DECOM CLOLMN TN TOM sea eres ete eo tetes seein a) se aise ela seialeletetelsisietstalowtcielsiefeiamm taietey= 246, 27 AGO ESP COMHNG he Comsnr asocee heones cosenacoeecoonl EdosHacéallbecoscoconsAcctecdcaceH soe 249. 99 Error of second determination ..-.......-..-.--.--- SUSU Os echt o2 SSS Ae Ra eee The first determination is adopted, because it is the final result of many years’ leveling over the line of the Erie Canal, as against the result of a long and broken line of railroad-levels; and because the canal-engi- neers have undoubtedly taken greater pains to get the mean surface of the lake than the railroad-engineers, to whom such knowledge was of no practical importance. At Montreal, the levels of the G. T. R. W. are checked approximately by levels run by the Montreal and Champlain R. R. Co., Montreal, sum- mer, water in river is 30 feet above mean sea by the G. Pode W.; by the M. & C. levels L. W. at Montreal is 69.7 feet below L. W. Champlain. The surface of the lake is 100.54 feet by canal from Albany; hence L. W. Montreal about 31 feet. Considered with reference to Lake Cham- lain, we haveits height above mean sea 100.84 feet by Hudson River and Vhitehall Canal, and 99.7 feet by G. T. R. W. from Portland. 634 ELEVATION OF BUFFALO, CLEVELAND ee ee AND MEAN SURFACE OF LAKE E 0 ; First determination. Mean tide at Albany, N. Y., by United States Coast Survey leveling. Surface of water in Erie Canal at Buffalo, by report of final levelings of Erie Canal, (see profiles accom- panying annual report of State engineer and sur- Nevor of New York, January 1, 1368, by J. P. Good- sell.) Water-prism of this section 9 feet deep; hence, bot- tom of canal at Buffalo. Surface of Erie Canal, Butfalo Bottom of Erie Canal, Buffalo Surface of Lake Erie, by observations at Cleveland and Buffalo from 1844 to 1857, and published in Smithsonian Contributions, by C. Whittlesey, 13860. Mean surface of Lake Erie at Buffalo Do Cleveland directrix, by mean of a very favorable month of synchronous observations at Buffalo and Cleveland on surface of lake, by Mr. C. Whittle- | sey and Mr. J. Lathrop. Rarvoend GOTREOBESS, Sd miocdoagoogoocdD boa9eD eb Oo. 0Nend6 0 Second determination. Permanent United States Coast Survey bench on granite block at Gloucester ferry, N.J., by United States Coast Survey Report of 1871. Mean tide in Delaware River at Philadelphia, hy United States Coast Survey Report. Mean tide at Philadelphia Philadelphia city datum, by leveling of Mr. S. L. Smedley, city-engineer and surveyor, and his assist- ant, Mr. Herring, January 11, 1874. Philadelphia city datum Pennsylvania R. R. datum, by report of Mr. Wilson, consulting-engineer of P. R. R., 1874. Pennsylvania R. R. datum or base of levels, called H. T. at Philadelphia. Bee baret, Market street depot track (The above elevations are from a profile of the last computations from releveling the whole line, agree: ing within one foot with the “old construction-levels at Pittsbur eh. Report by Mr. Wilson, consulting: | engineer, April 29, 1874.) Alliance, by P.F.W.&C. BR. profile, 1872 PAllivam CoN(GrACK) ss cis\s)-cujzjersi~ ciescleuicteloletciniers eisictelsia el reiele Cleveland directrix, by profile of C. & P. R. R., Tre- » ported by Mr. I. Pillsbury, February 11, 1858. Cleveland directrix Crestline, (track,) by profile of P.F.W.&C.R.R.... Crestline Cleveland directrix, by profile of C. C. C. &I. R.R., reported by Mr. I. Pillsbury, February 11, 1858. Cleveland directrix Cleveland directrix, mean of Cresiabias and Alliance routes. Mean surface of Lake Erie Third determination. Mean tide Albany, by: United States Coast Survey. --. Buffalo, N.Y. Co & L.S.R.R. depot track, by profile of N. ¥.C. R. R. Buffalo, N. Y.C. depot track .......... dosodocde Feet. GEOLOGICAL SURVEY OF THE TERRITORIES. Various datum-planes. Above M. T. foot of Eight- eenth street, New York . Above M. T. ‘Albany Above bottom of Erie Canal. Above bottom of Erie Canal, Buffalo. Above M.S. of Lake Erie from 1844 to 1857. Above M. T. Raritan Bay, equal mean surface of Atlantic. Below U.S. C.S. bench..--. Below Philadelphia city datum. burgh. Above Union depot, Pitts-: burgh. Above M. 1. New York Above tide at Albany, as- sumed to be M. T. face of Atlantic above mean sur- Ocean. Elevation in feet test cece 744, 913 GARDNER. ] GEOGRAPHY——-ELEVATION OF DATUM-PCINTS. 635 Elevation of Buffalo, Cleveland directrix, and mean surface of Lake Erie—Continued. Feet. Third determination—Continued. Cleveland, L. S. depot track, by profile of L. S. & M. 0. S. R. R. ” Cleveland, L. S. R. R. depot track Cleveland, L.S. R. R. depot track, by city-engineer re- port. * Olevolandidinecinixs.- asa alse salar ce ee sie ce ele wate wie sisal sate nlstal Qovets |e slate clelaater arom etaierefe cere isicree MeAMESUTIACOlOLWUIKS) HTC yo sa=c cassis saemcace seees case cece ase meee cme ie siaetne memeaie acess Fourth determination. Various datam-planes. Above Buffalo depot track. above mean.sur- face of Atlantic Elevation in feet Ocean. 575, 27 572. 67 Junction of the N.C. & Pa. R. Rs., on main line of Pa. R.R., west of Harrisburgh, by profile of N.C.R.R. Hirebere, Market street depot track ...........-.. Above M. T. Baltimore... Below junction of N.C.... es : Surface of Lake Erie, (year not given,) by P. & E.R. R. Sariscoomuake-E rien (yearn known) = cesestes sae lane) Saas teeta lao nes can en inate Sh eee eens Fifth determination. Erie Railway depot at Dunkirk.........-.-..-.------- Surface of Lake Erie at Dunkirk, by profile supposed to be from construction-levels. (Lhe present chief engineer reports that the line has been rerun, and that the old and new lines differ over 20 feet in some places. After examining the old and new levels, he gives preference to the old, but considers both incorrect.) Cleveland, L. S. depot, by L.S. & M.S. R. R......--- City directrix Geveland (directrix. js.) ae te gosee sates cite cise cis oeitaeye (This result is rejected in making up the means, be- cause the levels are condemned by the chief engi- neer of the road.) Sixth determination. Surface of Lake Ontario, by G. T. R. W. of Canada Surtace of water in Detroit River opposite Detroit, by G. W. R. W. of Canada. Surface of Lake Erie by State geological survey report. aie eel do Below Dunkirk ........... Below Cleveland depot. ... Below Dunkirk ........-.. Above mean surface of. Lake Ontario. Below river at Detroit. ... muTince Ole lakeeh ross yeas seen msnias eo ee LU Se ce Jue ecaacabeataacae Final results. Lake Erie: First determination Second determination Third determination.....-......------- SSeidOsaRR ed beseeteceEecodce Fourth determination ITP MOSLOLMIN AEGON. ate ses ee en eee cin ecn ior isicic||sewbeseae «listens SUMPMIGSLELMIN dblOM ance conan eer cee cree nesses eel ccccscccanlssoawe See eee ee ee eee ee ee Adopted result. Surface of Lake Erie, mean of observations from 1844 to 1857. Differences of other results from the one adopted. eee twee eee meee wonees Fourth determination differs — 2.33 Sixth determmation differs). ..222-----.-sccccceces,.n0- — 141 (The first determination is adopted, because it is the final result of many years’ leveling on the Erie Canal, connected with the mean of thirteen years’ observa- tions on the surface of the lake.) Cleveland directrix : First determination Second determination Third determination eee do. ee ee ee eee ee 573. 08 572. 037 572. 670 570. 750 [581.20] 571. 67 573, 08 eee eee ee errr 636 GEOLOGICAL SURVEY OF THE TERRITORIES. Elevation of Buffulo, Cleveland directrix, and mean surface of Lake Erie—Continued. Pto ees Feet. Various datam-plenes. Ble.) < aeog BSo8 Bako A Adopted result. Cleveland directrix, (this is high-water mark of 1838 |..........|..-.-.0----00-----00---0---- 575. 68 on pier.) Differences of the other results from the one adopted. Second determination differs.....-..------------------ = WoW pee coceosasesscesesessonesao|sosocsese Third determination differs...-.......-.--..---------. SOR CUN lb socnuedeneksoeseseeebdounsellescucccces The first determination is adopted, because it is the result of many years’ leveling over the Erie Canal, connected with Cleveland by a very favorable month of observations on ‘the lake surface, and connected with mean sea by the levels of the United States Coast Survey. The United States Coast-Survey line from their tide-gauge at New York to that at Albany was run for scientific purposes, and is undoubtedly leveling of the first quality. The Erie Canal has been in process of con- struction and enlargement for over fifty years. During this time the levels must have been rerun many times, and the benches and compu- tations checked by a succession of different engineers. Their final report should be of the highest authority. The mean surface of Lake Erie, during a month with light winds, when the fluctuations of the lake were small, is considered a level plane for connecting the west end of the canal with Cleveland. I think these reasons sufficient to justify me in accepting the first determination as against those by the railroad-lines. The result may then be considered as showing great accuracy in the railroad-surveys, which are from 480 to 600 miles long, and yet differ but about one foot from the canal-levels. At Harrisburgh, where the lines of the second and fourth determi inations — cross, the checking is very close. The height, as brought by the U.S. C.S. and Pa. R. R. from Raritan Bay, one handred and seventy-five . miles, is 319.91, while that froughy won Baltimore by the N. C. BR. BR. is 319.75; the two differing only 7 7% of a foot. The elevation of this — | same Market-street depot at Harrisbur gh by the P. & R. BR. B., reported to me by the chief engineer May, 1874, is 308. 03 above M. T. Philadelphia, which would be 311. 08 above M. ie Atlantic Ocean. This line is evi- dently in error about 8 feet betwe2n Philadelphia and Harrisburgh, but I believe it to be mostly in their computation, and not in the ‘instra- mental work. At Pittsburgh the Pa. R. R. is again checked by the B. & O. BR. B., which, in-a number of reports, give the elevation of their depot as 735 feet above mean tide at Baltimore. By the report of the city-engineer, the B. & O. R. R. depot track is 7.75 feet below that of the Union depot; hence the elevation of the track in the Union depot at Pitts- burgh, by the B. & O. R. R. above M. T. Baltimore, is 742.75 feet. That by the Pa. R. R. was 744.91 feet above M.T. Raritan Bay. As it is not known to me how this mean tide was determined at Baltimore, nor is it known whether mean tide at Baltimore is the same as the mean ocean-sur- face, and as the B. & O. RB. R. levels have not been subject to as many revisions as those of the Pa. R. R., and the connection of the Pittsburgh q GARDNER. ] GEOGRAPHY—ELEVATION OF DATUM-POINTS. 637 depot is not known to be with the same grade given in the profiles of the railroad, I consider the Pa. R. BR. result as being the more reliable for the present elevation of the track in the Union depot. The line of levels from Baltimore, by the N. C. R. R. to Harrisburgh, and thence, by the P. & E.R. k. to Lake Erie, at Erie, a distance of four hundred and twenty-six miles, reaches the lake with an error that does not exceed 2 feet. ELEVATIONS OF LAKE HURON, LAKE MICHIGAN, AND THE CHICAGO DIRECTRIX. First determination. Lake Ontario at Oswego, by United States Coast Sur- vey and Erie Canal. : Surface of Georgian Bay, Lake Huron, at Colling- wood, by N. R. R. of Canada. Surface of Lake Huron in Georgian Bay...--......-.. Second determination. Sarface of Lake Huron at Sarnia, south end of lako, by G. T. R. W. of Canada. SERS Git ILA ROME hie pg anpeoke cabsbuEcubenotoeaesace Third determination. Mean surface of Lake Huron at Sarnia, by G. W.R. W. of Canada. Mean surface of laake Huroné:29!32 5.0) 052222222 4225) Fourth determination. Mean surface of Lake Erie, by United States Coast Survey and Erie Canal. Surface of Detroit River at Detroit, by State geologi- cal survey report. Mean Surface of Lake Huron, by G. W. R. W. of Canada. Difference of Lake.Erie and Lake Huron, mean sur- faces. WMeanisurface/of) bake Huron) .scesqcecnec= 22sec cc oe ' Fifth determination. Surface of Detroit River at Detroit, by State geologi- cal survey report. gaction of D. & M.R.R.and G. T.R. R., by D. & M. Surface of Lake Huron, by G. T. R. W. of Canada .... LURIES JEL Ee Sse ae evn S21. ae aa ae Sixth determination. Surface of Detroit River at Detroit Surface of Lake Michigan at Grand Haven, by D. & M.R.R. eeMUChi ran). tos. se cee asiewacn ssceesssesue nad Surface of Lake Michigan Seventh determination. Siero landidinecimix spot sees ct cccibsesececelwaeaes Crestline, by C.C.C.& I. R.R NC Pee Er en En A SAN Cre t OeN kw 8 te Chicago depot of P. F. W. & C.R. R. track, by P. F. W.&C. QR. BR. report, 1872. Chicago, P. F. W. & C. depot track Chicago city directrix, by city-engineer, 1872 EO MOIRO CLL Seeee ese ee oa.cic\sos cc tac eee dane na Mean surface of Lake Michigan for past twenty years, by city-engincer’s report. $22, Gas a8 Aas R oq Feet. Various datum-planes. ae Sos 2538 ito) x cence ee eee [eer e ee eee eee eee ee - eee eee 249. 99 340.00 | Above Lake Ontario..---.|._..__.... sedocabcoujoasteccoosombaccesosoomasns 589. 99 341.00 | Above Lake Ontario......|......._.. cece eens [serene een nee eee ee 590. 99 340.00 | Above Lake Ontario......|......._.. SSeS SOC e eno oS Seeaee eae ees 589. 99 See SSS nn nti n iii 573. 08 3,00 | Above Lake Erie.........]:......... 11.60 | Above surface of river at |._.-...... Detroit. IAL GD) |lscoccobcnodanesnocsbossoosbdllescoso omen tem ewe ewe | seen e wean ne cama wenn nen nenne 587. 68 3,00 | Above Wake Erie: ’..22 25022222222. 55.60 | Above water in Detroit |.......... River, Sept. 24, 1868. 43.00 | Below Milwaukee junction|......._.. 12.6 | Above river at Detroit, |..-...._.. September 24, 1868. 1526). Abowesiiakeukrices=se> canoes see eee nbSSoasads| |saspoanedoeosotidosecomadosse 588. 68 3.00 | Above Lake Erie.........|.......-.. 10.74 | Above river at Detroit, |........-. September 24, 1868. 13.74 | Above Lake Erie. .......-|.-./--.-2. Bae ee eee | aiainiateisatela aia sta saicters claeisiomntcts 586. 82 anise peso o|leosecd neoneocsO CocmeHedeoc: 575. 68 577. 30 | Above Cleveland directrix.|..-......-. 54 Pane lat a RP Be lL 2 1, 152. 98 DOONOM NE SLONy CLESULING Hae ercerceie | ee ee ete SEB a dec cl COSTES COR RSORSSre re scise ac 594, 38 85 | Below top of railin P; F. .. 22a: W. & C. depot. Se cull temwearnscreeine Oe eee Me eR Oe 585. 88 2.00 | Above city-directrix......).......... e 638 GEOLOGICAL SURVEY OF THE TFRRITORIES. ELEVATIONS OF LAKE HURON, ETC.—Continued. Surface of Lake Michigan, mean of twenty years .--- Alliance, by C.& P.R. R PANT TITIC OER alee eee ee ocameicestine ceejte ie Gisele clnie relesiyele 2 Chicago depot, track of P. F.W.&C.R.R., by P. F. W. & C., 1872, report. Chicago depot, track P. F. W. & C.R. R.....-.----.--- Chicago directrix, by city-engineers, 1872 Chicago GHEE CUWBRS o cog dabonedsooeuascoonasoeosesngades Surface of Lake Michigan, mean of past twenty years Chicago directrix, by P. F. W. &.C. R. R., mean of Al- liance and Crestline connection with Cleveland. Surface of Lake Michigan..................---....--- Eighth determination. Feet: Vorious datnm-planes. Cleveland directrix. Kees us aisle) sioaceimicmeisises te cscie soci see cite onl seieite raises cette mee nee eee Cleveland, L.S. & M.S. depot, by city-engipeer....--. 8. 50 bove GhoRNeWee. 6o546- 5505 Chicago, L.S.& MS. depot track, by profile procured 16.6 | Above Cleveland depot... at the office of chief engineer, October, 1873. Chicago, L.S. & M.S. R. RB. depot PLAC esses ore all alates sensi letetobe tetas race erent ote ete oe Chicago directrix, by city-engineer, 1872 ......-...-- 12. 20 polew track of L.S. & M - . depot. Chicago direetrisg see eee eeta ses sec chet arafeiele cinsateleto | eictercinte otal esieie sclotelstereroie cite lap eerie Surface of Lake Michigan, mean of past twenty years.|.......--.|.---------------------+----- Ninth determination. Menntsurface/ons ake, MTOM eects cee cel seeie nein sisal ere seie te all meyer eremierseeeinyoteseve ieee ise Mean surface of river at Detroit, by State geological 3.00 | Above Lake Hrie......... survey report. Usual height of water in river on June 1.....-...--.. 1.00 | Above mean surface of river. - Chicago depot of M.C.R. R., by M.C. R. R. report .-.. 13.20 | Above river at Detroit, June 1, 1869. Chicarordepot of VEC rR. 6c le CR wives eee naeeeal teaser cece Eee e eee eee eee eee eeee eee Chicago directrix, by chief engineer of I.C. R. R...---. 6.5 | Below I.C. & M.C.R.R. ; depot. Chicacodinecbhriag Me eg5 slo 2eie can teeta ce bitee srarecel ctr raye ta ieee leet tata mee ey ne On Meantsurtaceiot ake Michi gamieeecteciesesisersciacsesisisal eee nee cece nee nelseeieeciceeiser nine eee Final results. Surface of Lake Michigan and Lake Huron: (2) First determination......--------------------- Huron ..| State of water unknown. (2) Second determination. --..--.2....-.--2-..52-. Sedo hte al ee ON GN ees a eae ae (2) Third determination..........-.....-..---.--- ..-do ....| Mean surface ...----.-.--- (1) Fourth determination...-.-.....--.-.---.----- BEE O meelteecee dO CEST aN (1) Fifth determination........-..-..-....-..-...- .do ....| State of water unknown (1) Sixth determination. ..-.-.-..--..-..--.---.--. Michigan sous COS eee (4) Seventh determination.........--..--.----.--- {ido 3. ..| Mean surface) -22--.222---- (4) Eighth determination..........--...----.----- Jd oes eee 0:2 a eee ae (1) Ninth determination....-.------.---.-----.--- Michigan Bata Ose eee eee a (The figures in parentheses indicate the relative weights with which the different determinations enter into the mean.) Adopted result. . Meantol nine determinationsaceeaecicatscee sce cerer ell maceicec eee cise eee eeeee ee eeneee Mean surface of Lake Michigan for past twenty years.|.....-....|---------------------------- The extreme range among the nine results is..-..-..-. CO ie Haid es aaah a eS Se (This amount does not exceed the known fluctua- tions of the lakes.) Chicago directrix: Seventh determination Highth determination ......-- ? F Dudes ale epee eas peta er na el a ea ee ALLS oh ec Ae Result by subtracting 2 feet from adopted result for mean surface of the lake. Adopted result. C@hicacorcitiy-dinccinixass= see see eaiee eae eeeee The observations at Chicago make the city-directrix. - 2. 00 Below mean emo of Lake Michigan for past twenty years. | above mean sur- - face of Atlantic © Elovation in feet carver] GEOGRAPHY—ELEVATION OF DATUM-POINTS. 639 Hence, if the height 589.15 feet is adopted as the mean surface, 587.15 feet must be the elevation of the city-directrix. I have given their respect- ive relative weights to the different determinations for the following rea- son: The fourth, fifth, sixth, and ninth are of least value, because they depend on the height of the water at Detroit, being 3 feet above Lake Erie, as reported by the State geological survey. The original data upon which this report depends cannot be found, and I therefore consider it ‘open to much doubt. The first, second, and third determinations are given the value (2) because they are first-class railroad-lines, run from a base at Toronto, called surface of Lake Ontario, but which I do not know to be the mean surface, but simply asswme it to be so. They run directly to Lake. Huron, but only in one case is the state of the water given; and then I do not know of how many years it is the mean. These results should, of course, be far better than the fourth, fifth, sixth, and ninth, but are not nearly so probable as the seventh and eighth, which depend on railroad-lines run directly from the Cleveland direct- rix to the Chicago depots, which in this ease seem well connected with the Chicago directrix. The height of the Cleveland directrix, as brought through on these same railroad-lines, the L. 8. & M.S., the P.F.W.&C.,0.&P., and 0.0.0. & I. R. Rs. had checked so closely with the canal and lake surface result that they are entitled to great weight in their westward extension to Chicago. In connection with these directrices of Cleveland and Chicago, the fluctuations of the lakes have been observed, and the mean surfaces determined. For accounts of these fluctuations see Smithsonian Contributions, 1860: Fluetuations of Level in the North American Lakes, by Charles Whittlesey; also a recent report from the Dudley observatory, Albany, N. ¥. Determinations 1, 2, 3, 7, and 8 are the only ones which rest. upon sufficient evidence to make them of much value, and it will be noticed that the range among these five is only 2.53 feet, with the lake at an unknown stage of the water. The range among those three that refer to the mean surface of Lakes Huron and Michigan is only 1.53 feet. I think therefore that the elevations of the mean surface of Lake Michigan and of the Chicago direetrix will probably not be open to a change of over one foot. We have here at the Chicago directrix an opportunity for comparing the results of two very long and independent lines of railroad-levels, those of the N. Y.C. and L. 8. & M.S. R. Rs., and of the Pa. RB. BR. and P. F.W.&C. B. RB. I give the results in detail: 640 GEOLOGICAL SURVEY OF THE TERRITORIES. From mean tide New York Bay to the Chicago directrix. —. Bes 2s as : Tod 5 ; Feet. Various datum-planes. g los, . =eSe soso Sako eva By the N. Y.C.R. BR ‘ Mean tide iia by United States CoastSurvey.| 4.84 | Above M. T. New York ..}.......... Buffalo depot, by N: ¥. ©!) R. R..-...-.--2--------- 578.23 | Above T.at Albany .-.-.-|.-..--.-.. Chicago depot, by L.S.& M.S.R.R.-....-------- 17.30 | Above Buffalo depot...-..|-.---..--. Chicago GWEC HEIN, 6424 bbb sosSobaseodeobensdases 12.80 | Below Chicago, L.S. & M. |........-.. S. depot. BD) OP erase vase eye ieelntcleteinie ate e eisinstereleleis eielefole =I iefell iniaise atersiats Seieeieiseiee isis leieertetee ee Ieeees 587. 57 Total distance from New York Bay, 980 miles. By the Pa. R. R.: . Pa. R. R. datum, by United Stee Coast Survey. - 6.913 | Above M. T. Raritan Bay.|.......-.. Pittsburgh Union depot, by Pa. R. R......--2-.--. 738.00 | Above Pa. R. R. datum....|.----.---. Chicago depot, by P. F. W. & C. RTS ama he 151.00 | Below Pittsburgh depot -..|.-.....--. Chicagodirectrixcseeeerecscseeee teeter e eer 8.50 | Below Chicago pepo Uy wl hitenall kere a terayeee NO oye gate he ne aaa ene RN HE OS reso lhe endian UNMIS Srey An esr 585. 41 Total distance, about 900 miles. pete directrix, by N. Y.C.&L.8. & M.8.R.R., 980 | 587.57 | Above M. T. New York...|........-- miles Chicago directrix, by Pa.R.R.& P.F.W.& C. R.R., | 585.41 | Above M. T. Raritan Bay.|.-.-..----. 900 miles. ID HIRT NCD .ooccacssobsos on osseous SodogudsesossaouaseNs PhD |lecogoenbcasvssscscos0oc0cSoe|/soconece02 These lines are about one hundred and fifty miles apart through the first half of their course and about fifty miles in the western part. The Pa. R. R. crosses the Appalachian-mountain system in a diffieult place, rising to a height of 2,290 feet, among ridges that must exert con- siderable attraction upon the level, while the N. Y.C. and L. S. & M. S. Railroads are through compar atively level country; and yet, after this long course of about nine hundred miles, they reach Chicago with only two feet difference in their levels. The result seems truly remark- able. The height by the Pa. R. R. differs—1.74 feet, and by the N. Y. C., 1.8. & M.S. RR. R. +0.42 feet from the adopted elevation. The N. Y. C. R. R. is checked at Buffalo, three hundred miles from Albany, by a connection with surface of Lake Erie, state of water un- known, but assumed to be mean surface. The railroad-levels are 0.7 foot too high. At Cleveland, four hundred and eighty miles from Albany, the railroad-levels are 0.41 feet too high, and at Chicago 0.42 feet too high. The Pa. R. R.is checked at Harrisburgh, one hundred miles from Philadelphia, where it is intersected by the N. C. R. R., bringing its levels from mean tide at Baltimore, eighty-four miles. The two lines of levels differ but 0.16 feet. It ischecked again at Pittsburgh, three hun- dred and fifty miles from Philadelphia, where the B. & O. R. R. inter- sects, bringing its levels from mean tide at Baltimore about three hundred mniles. The levels by the Pa. R. R. are 2.16 feet higher than by the B. & O. ht. R., but the connection of the profiles of the two is not exactly certain. It is, however, not improbable that mean tide at Baltimore is a little above the mean level of the ocean. At Alliance, the P. F. W. & C., the -extension of the Pa. R. R. line of levels to Chicago, is checked by the C. & P. Rk. R. from the Cleveland directrix. The elevation of Alliance by the Pa. R. R. and. P.. F. W. & C.R. R. is 1081. 61 feet; that by the C. & P. BR. R. is 1083.23 feet; the P. F. W. & C. being ’ probably too low. At Crestline it is checked again from the Cleve’ directrix, the ele- vation by the P. F. W. & CO. RR. being 1152.51, and that by the C. carpyer] GEOGRAPHY—ELEVATION OF DATUM-POINTS. 641 C. C.& I. R. R. 1152.98; the P. F. W. & C. being probably too low. At Chicago, the P. F. W. & C. BR. R. levels are 1.74 feet too low. The mean of these checks at Alliance, Crestline, and Chicago would make the whole of the western part of this line 1.27 feet too low. I therefore think it not improbable that the elevation of Pittsburgh by the Pa. R. R. may be about 1 foot too low. Considering all the evidence, I should be inclined to adopt 746 feet as the elevation of Pittsburgh Union-depot track instead of the Pa. R. RB. result of 744.913. The longest connected line of railroad-levels that we have an opportu- nity to check at Chicago is that of the G. T. R. W.of Canada, from Portland, Me., to Detroit, Mich., and thence to Chicago by the M. C. R. R. The details of the line and its results are as follows: Elevation of Chicago directrix by G. T. Rh. W. of Canada and M. C. R. R. Bee S85 aes Feet. Various datum-planes. | Ba , O08 BeOS sofo Baas ic. Mean high tide at Portland.-...-..---2-.------------- 4.5 -| Above M. T. Pertland...-..|... sees Mean tide, G. T. R. R. datum at Three Rivers .....-... 6.77 | Above M. H. T. Portland..|.-........ PROT ONTO EE seis sats acts s «ss sinejenmeaibaieae netainatnoe ties 239,78 | Above G. T. R. W. datum .|.......... Metro qANChON ee ees cise ensse este see td Bels 340, 22'| Above Toronto ........-.-|.-...----. @iicasordepoteee ssp aes 22 slnateeeisiele ie einen ~/earqoeteele 4,70 | Below Detroit junction..../..-...-... Clana Cinegiabe 36 4 sates sh seedomaacdsoneocober cess 6.50 | Below depot of M.C. R. R.}.-...-.--- QO) » bose ob Soneog se qoAssecoonouseaoogeesbor pdncd|lbopeqoucnadloscg aososdobASaunSecEEdechos 580. 07 Distance from Portland to Chicago 1,142 miles. My adopted elevation is 587.15 feet; therefore, this line of levels, eleven hundred and forty-two miles long, appears to be in error only 7.08 feet, and the greater part of this error is in the M. C. R. R. line in the last three hundred miles. The quality of the line in different parts is shown by the checks at various points. The first check is at Toronto, six hundred and thirty miles from Portland, where the lineis connected with the surface of Lake Ontario, the state of the water unknown, but assuming it to be the mean surface, the levels are 3.72 feet too low. The next check is at Sarnia, on Lake Huron, eight hundred miles from Portland, where the line is connected with the surface of this lake; the state of the water is again unknown, but, if assumed it to be the mean surface, the levels are 1.88 feet too low. At Detroit junction we have -an approximate check by the height of that point, by the M. C. BR. R., above H. W. in river at Detroit, June 1, 1869. The M. C. R. R. gives the height of Grand Trunk junction at 17.90 feet above H. W. 1869. This point we have supposed, by the geological-survey report, to be about 4 feet above the mean surface of Lake Erie; hence the junction would be 21.90 above Lake Erie, or 594.98 feet above M. T. The eleva- Sion of this point by the G. T. R. W. is 591.27, a discrepancy of 3.71 _ feet. From this, and from the ninth determination of elevation of Lake . Michigan, it appears that there is an error of about 4 feet in the M. C. Jt. R. profile, in the difference of elevation in its termini. The length of this line is two hundred and eighty-four miles. Establishing the elevation of the Chicago directrix gives us the means of checking another very long line of levels, extending from M. T. at New: Orleans to Chicago, a distance of nine hundred and sixty miles. The details of the line are as follows: 41 G8 642 GEOLOGICAL SURVEY OF THE TERRITORIES. From mean tide at New Orleans to Chicago, by N. O. J. & Gt. N. R. R., Miss. C. BR. R., M. § T.R.R.,M.§ L. Rk. KR. N.§ N. WK R., A. W. slope of Mississippi River fourteen miles, M. § O. KR. f., and Ii. C. kh. R. ELEVATION OF MEMPHIS, TENN. PLO oes aS Ase Feet. Various datum-planes. 8 =i P mood 2538 (>) Sako oa Canton, Miss., by N.0.J.& Gt.N. R.R..-.-..-------- 240.00 | Above M. T. New Orleans.|..-....... Grenada, Miss., by Miss. C. R. R..-------------------- 56.00 || Below Canton ----.5 22... |s22 25.2. Memphis, L. W. in Mississippi River ..----.-.-.-----. 0.00 |Above Grenada. ....-.....]..-..----- Memphis, (supposed to be depot,) by M.& T.R.R.... 75.00 |.----- CO) AEE SEA eer oconasenslooadsooun Memphis, depot ...---.------.----- 2 eee ee ee ee fee ee ele ne ee eee eee eee 259. 00 Memphis, L. W_......-.---------- 222-2202 eee n een [eee ee eee ee ee nee eee 184. 00 Memphis City datum + 100 feet = H. W. previous to 41.00 | Below M. & T. R. R. depot. 218. 00 1858, by city-engineer report. ’ Grand Junction, Tenn., by M.C.R. R....---.--..----- 334. 44 | Above Canton ....--.-.---|...---.--- (Gheniaxdl Ibm ssasgaseneosseaaooosspasdsouosuascooss 574. 44 | Above New Orleans, M. T. 574, 44 Memphis, by M. & C.R.R.......-.....-.---------2--- 329.47 | Below Grand Junction....).-...-.--- Wilerapovlsy, Cleyoers INE 6 Oh IM I. co oeososdonaobogndadasdo|acoscossea|lecs socoeanacuoasosseconqcas 1" "944/ 97 Memphis, H. W. of railroad reports, 1844............ 25.00 | Below M. & C. depot .-..-- 219. 97 Memphis City datum + 100 feet = H. W. previous to 27.00 | Below M. & C. depot ...--- 217. 97 1858. (This city datum + 100 feet = H. W. is either the H. W. of 1244 or of 1850; but they differed only 0.4 | - foot. The elevatiowof this H. W. mark in several reports of the M.& C.R.R. is given as 220.44 above tide in Mobile Bay. As the only records that I have of the M. & C.R. R. are above L. T., Mobile Bay, this 220.44 may be above L.T. In this case Memphis H. W. would be 218.74 above Mobile Bay M. T., but in either case the results from New Or- leans and Mobile differ very little.) Final results. Pcp H. W. previous to 1858, 100 feet above city- |.-.......- Above New Orleans M. T. 218. 00 atum. Do 219. 97 Do 217. 97 | Memphis H. W. 100 feet above city-datum..........--|...-..---- Above New Orleans, M. T. 218. 65 7 Memphis H. W.100 feet above city-datum..........-- 220.44 | Above Mobile Bay.-...-..].--.------ a D Ys Wes SCs ors Me yts RN PAs Ae aN ene ee ete 218.74 | Above Mobile Bay, M. T ..|......--..- MEMPHIS TO CHICAGO. SS) Aas c = qq Feet. Various datum-planes. ge. aecs BSes SakS io. Memphis, Tenn., City datum + 100 feet = H. W. pre- 218.65 | Apove M. T. New Orleans.|.......-.. on to 1858, by N.0.J. & G. N., M. C., M. & T. : i. Hus. McKenzie Junction, by M. & L. R. R..--..--..------- 269.56 | Above city-datum of |.......... Memphis + 100 feet = H.W. L. W. Mississippi River, Sept. 30, 1858, at Hickman, Ky.| 213.00 | Below McKenzie....-...-.|.--..--.-- H. W., ey at Columbus, by Humphreys and Abbot's 37.80 | Above L. W. 1858) 22 -- 5-22 -|2 sss o- an report. (This makes the H. W. slope of the river, from Hick- man to Wemphis, 0.49 feet per mile, supposing the distance to be 190 miles.) : y H. W. 1858, at Columbus, Ky., 14 miles up the Missis- 7.00 | Above H. W. Hickman ..-|.......... sippi by slope of river. ale at Cairo, by preliminary survey for M. & O. 11.50 | Above H. W. at Columbus.|.......... Chicago directrix, by chief engineer I.C. R. B., Octo- 258.50 | Above H. W. at Cairo.....|....... ose ber, 1873. GARDNER.] GEOGRAPHY——ELEVATION OF DATUM-POINTS. 643 MEMPHIS TO CHICAGO—Continnued. PO @ H-m Sak Ags Feet. Various datum-planes. elisee wooR ~b a B23 Sano = Chieago directrix. --.------------------------------ eeal[cncosacace Above M. T. New Orleans. 590. 01 From the figures given above we have also Memphis, |...-...--.. Above New Orleans M. T . 218. 65 Tenn., H. W.= city datum + 100 feet. Ayia NnS, TEL WWYo WeSYs) = oe se Seba godboeconondcoseosascose 1.00 | Above previous extreme |.......... IDG) cmmoond osonecdopecsonojscododapsoopyopossoacol|>napecnoos Above New Orleans M. T . 219. 65 TEC mmam, UG, EL Wo IGE) cca snocecoonoosaoncoEdcedollonsosonass|losaasdone sesacc coadsunSeeas 313. 01 Salma nae, Baie, Jas Wyy/od GB) oa con eons onorcecosonaSdbecd lseonensbaoljseqdoo coneconmaBeeeanonecras 320. 01 (Grrind, 1L VV. TBS S eco secs cncanscoccanesossoee cote) |scocossecs|[Se5 Soccsosepocspesesocganes 331. 51 Cairo City datum—=ordinary L. W.-..-.-.---~-..----- 40.38 | Below H. W. 1858 ..--...-.-. 291. 13 The adopted elevation of the Chicago directrix being 587.15, this line of levels, nine hundred and sixty miles long, reaches Chicago with an error of only 2.86 feet. The error of connection, due to using the H. W. slope of the Mississippi River for fourteen miles, would not probably exceed a foot ortwo. At Memphis, the line is checked to within 1.8 feet with the levels from Mobile Bay. At Columbus and at Cairo, the line is checked by the M. & O. R. R.; but the only reports of this line which I can find give the elevations as determined by an experimental survey, the results of which were reported to the second meeting of stockhold- ers, in 1850. The character of reconnaissance-surveys is such, and the results have proved so inaccurate when I have been able to compare them with the construction-levels, that I have not felt justified in giving» the results of the M. & O. R. R. preliminary survey to Columbus and Cairo any weight as compared with the profiles of constructed lines. It is, however, upon this preliminary survey that Humphreys and Abbot, in their Hydraulics of the Mississippi River, base their elevations of Saint Louis, Cairo and Columbus, and consequently their slope of the river from Cairo to Memphis. RESULTS BY M. & O. R. R., PRELIMINARY, COMPARED WITH ADOPTED LEVELS. 2 Sie Bae Aas : oe Feet. Various datum-planes. aay. Eos Baas oa H W. at Columbus, by M. & O. preliminary survey.--.) 308.50 | Above M. L. W. Mobile Bay}.--..-.--- MEH ENIOD ILO Bayes = -snjn sce anaemic cece cle ae cee 167) || Alene) WE Ih WY too cohoscce|ponaescesc H. W. Columbus, by M. & O. preliminary...-..-.------ 306. 80 | Above M. T. Mobile Bay -- 306, 80 H. W. 1858, Columbus, by N.0.J.&G.N.,M.C.,M. & 320.01 | Above M. T. New Orleans. 320. 01 T.,M.&L., N.& N.W. RR. H. W. Cairo, by M. & O. preliminary .--..--..--..----- 320. Above L. T. Mobile Bay. .-|..-------- OMe Saree sees occ ten woc\sea- ae ate ac sceitetomoe Above M. T. Mobile Bay -. 318. 30 TEL Vi’ TSB ies (Cray Tipe (Oy neta Oe ais NY BOR read Bee Agee eee) Sempcoeeee acide TeuedosSScecs 331. 51 M.&L., N.& N. W.B.R. . It will be seen further on that the elevation of the Cairo City datum, as brought from New Orleans, is within a foot of that brought from the Cleveland directrix, via Cincinnati and Indianapolis. In summing up all evidence on the elevation of the Cairo City datum, on page 647, it will be shown why I reject the levels of the M. & O. R. RB. If we consider now the line from Portland to Chicago and from Chi- cago to New Orleans as one, we have a connected chain of railroad-levels 644 GEOLOGICAL SURVEY OF THE TERRITORIES. twenty-one hundred miles long, starting from mean tide at Portland, Me., and reaching New Orleans, La., with an error of —9.9 feet. If we join the N. Y.C. and L. 8. & M.S. BR. Rs. with the line from Chicago to New Orleans, we have a connected chain of railroad-levels, eighteen hundred miles long, starting from mean tide in New York Bay and ending at mean tide New Orleans, with an error of only —2.44 feet. Using the Pa. R. R. and P. F. W. & C. BR. RB. for a through-connec- tion in the same way between mean tide Raritan Bay and New Orleans mean tide, a distance of about eighteen hundred miles, the levels reach New Orleans with an error of —4.61 feet. These results will give some idea of the accuracy of extended lines of railroad-levels when properly connected. ELEVATION OF CINCINNATI CITY BASE, WHICH IS STANDARD LOW WATER IN OHIO RIVER, 62.50FEET BELOW H. W. 1832. Pro © H.a Sad aS AS zi Feet. Various datum-planes. ga. BESS BoD Paso Gano | First determination. a) L. W. Ohio River at Cincinnati, by Miami and Erie 133. 00 | Below Lake Erie........-.}.......-.. Canal. Meanisuriacelotmiakeshirionereeseceoecriccisceemeraeises eeeeee eee teenie cen ee eee eect eeee 573. 08 Ibs Wo Gis CHINE oc ogenoaSdoooSonedoonooss 99500e08||so5enaso0se]le see onoonoondsacdcosed esse 440. 08 Second determination. Columbus, Ohio, by C.C.C.& I. R.R-.......---------- 167.33 | Above Cleveland directrix.|........-.. Clovelandidirectrixiess te eseu es rece secre lacie Siotarsiete | eeiaaetcrstote | retreive Uae operon ate eral era ere bterees 575. 68 Colum bis OT a ee eee ee ee Marat cis tebe cye el behead a) Wie 743. 01 L. W. in Ohio River at Cincinnati water-works, by 307.58 | Below Columbus depot....|.......-.. Col. & X.and L. M. RB. R. AR Wiel © 1DGIM MAG sis sass See osc eya pate le inven acetate ee cis boteiarete aia tall ate Se cRyerei| eyave o sierctor ete everett ereioiete areata 435, 43 Third determination. Columbus, Ohio, depot track, by ©. C. C. & I. from |...-...-..|------.------ 2-0 -seeese---- 743. 01 Cleveland directrix. Athens, Ohio, junction of M.&C., by C.& H.V.R.R 96.00 | Below Columbus depot..-./.....-.--- ANTOGAS CHS owaGnlon, OF IMG C20 sooaduss. soonest osoucsunslloadoqnsadallscaasecousde senoesocoscseacs 647. 01 L. W. at Cincinnati point, 62.5 feet below H. W. 1832, 207.00 | Below Athens = city base, by M. & C.R.R. Sees el seer City base siiiWeCincinm ata oes hate ee eee a yore oe eae aL ea be co t..| 440. 01 Fourth determination. ID NARMS ty ID) Ce IWIN, 1h) 6 oem oboe ot aaeouedosemooRoseeE 180.00 | Above Lake Erie at Toledo.|.......... L. W. at Cincinnati, by C.H. & D.R.R.-...-..---.---- 313300) Below, Dayton sence se = |aseeee eee Mreanisurtace Of TWalke Wrie os ir eee ee) es ee pa epee are ete ye vol Heal are e ete mere tcl ete ea 573. 08 FEF Wis CANCINMAGL soo seis Seiad oe eek SSeS Me acon oe ce eema eal ee Sete eras | Neca cere saat ee roe Stereesee es 440. 08 » Lifth determination. L. W. Ohio River at Parkersburgh, by report of aline |.......... Above M. T. Baltimore. ... 573. 50 of levels run from Cincinnati to Parkersburgh, (not the M. & C. R. BR.) L. W. in Ohio at Cincinnati, by same report ---......- Final results. L. W. in Ohio River at Cincinnati, city directrix: (10) eEirshideterminationee=-ee-seee eee reeee ences 440, 08 (1) Second determination. . 435. 43 (1) Third determination ... 440. 01 (1) Fourth determination .. Saye 3 ; 440. 08 (i) pRutthideterminationess ere seeee eee eee eeneE ee ae 440. 00 Meantwathiwerehtsererereneress acacia ter nee se eee 439. 74 Adopted result: (22252222552 524- 22 je RAE eae Oa re 439. 74 (The first determination is given a weight of (10) be- cause itis a canal-line. The second and third de- terminations are well checked at Columbus by the B.C. & St. L. R. R. from Pittsburgh.) Adoptedvelevation ofsPittsbung heen eee ree snes |e eee | ee eee ne ee ee eee 746. 00 Columbus depot track, by P.C. & St. L.R.R.--.--.-.-- 3.80 | Below Pittsburgh......--.].--.------ Columbus’ depottracke ysis ee Me BS OS IE Ca er aa 7142. 26 cee GEOGRAPHY—ELEVATION OF DATUM-POINTS. 645 This result differs but 0.8 feet from that by the C.C.C. & IL. R. R. from Cleveland directrix. _ If we consider the depot track at Columbus, Ohio, as the point of junction of two long, connected lines of levels from the sea, one being from New York by the Erie Canal, surface of Lake Erie, C.C. C. & I. BR. R., and the other by the Pa. R. R. and the P. C. & St. L. R. R., we should have the elevation of Columbus by the former as 743.01 feet above the sea, and by the latter as 741.11 feet. The difference between the two is only 1.9 feet, though the shorter line of the two is over six hundred miles in length. ELEVATION OF INDIANAPOLIS. PHO an ngs Feet. Various datum-planes. a =p a Sess p2e8 aso iS (Cmts Ibe V7, Gin AOS) sce sea caagasoedooscct bapdolloodecdsced| sasnonnecooosconoebnascadoes 439. 74 First determination. Cambridge, by W. W. Val. R. R....-.-...-.-.--------- 508.00 | Above city-base ....-...-.]..----.--. CPT TNGIED -ccopsnoeeoos gabacesassesooscsecensescosasd|soocdcc cod|[pasacaGocoqe decossrosscanace 947. 74 Indianapolis union depot, by P.C. & St. L. R. R...---- 227.00 | Below Cambridge...------|.......... InAGianNey VOlbis weTAN GE cons Sondes Gosncoanadeat boned sooscHouud eeeoonceeee Fee a eeee ae 720. 74 Second determination. 4 Indianapolis union depot, by 1.C.& L.R.R......---- 283.01 | Above point supposed to |.......... be city-base because H. W. 1858 is 58 feet in profile. Pudianapolisunion, depot tracks. os aeesalaia seer | eeincicine cial: sae cies sesicee sarsistaeielctertats 722.15 Third determination. City-datum of Fort Wayne, by report of city-engi- 196.00 | Above Lake Erie ......... 769. 08 neer, who says it was brought by canal. As this elevation of the city-datum is not from original canal-reports, I do not dare to accept it, and prefer the following, as previous results have shown the C.C.C. & I. and P. F. W. & C. to be so reliable. @resiline by CiC. C2 él Rae sas eee secs 577. 33 | Above Cleveland directrix.|.......--. Hota WiaiyN Olde POU sence see sae ee seca ac cciee sim 348:00' | Below. Crestline: -=---- -2-.|---+----- DOV. sas oes Soho abn Gace nese oe boaaeacKes na 229, 33 | Above Cleveland directrix.,]...---. Bee plevelanGiGire cheix ces eee ee ee eee eee ee soacac wel s odes ceds/sall sorciee aes saeeec aeemeinaRing 575. 68 HOGI Vy NO Ae NOb OLeea Hawa Gen Ose sete teeta alsa cl soa acu tetos cil melee stien Sects were maitre ero ats 805. OL City-datum, by city-engineer......--.-..--..--------- 15.31 | Below P. F. W. & C. depot-|.----..--. Homi Wayne VClGy-CAtU Meant ee ee eae eas eiiae cn al se caiele oie of ese ne aejerajaieicie aie sede eeiartcis 789. 70 Fort Wayne, F. W.J.&8. BR. R. depot .--..--.----.--. Shi) Below, city-datumiesee see. SAEEERC OTIEO fH VV ay lVie) Oc) (sieve thers spe eee iterate ater tm } Above F. W.J. & S. depot.|..-...---- BI) Pee ee cee ae te este ace ete OLE Pel olaol crate comic K cape lebsya ia ail hi Stsieicieted aye epee eels aust Serciaia oP 787. 60 Cambridge, by F. W.M. & C.R.R f Aboyejanctionese eee see |peeeeeneets CAIRDTIAS Oy see eee nse ae ere eee eee eee abe salasecce cee Ae 961. 48 Indianapolis union depot, by P. C. & St. L..----..----- 227.00 | Below Cambridge.-...-.---|..-------- Pan APO SHIN ONVAe pO bie as sees teers eet telacice aos lnicie ome ctiais lie ncine Mlciemnteeie ele rinienteitelareicine 734, 48 (As it is not known that the depots at Fort Wayne, referred to by the railroad-protiles, are the same as those of the city-engineer’s report, I do not feel cer- tain of the connections by this line. I, therefore, reject this determination, and use only the first and second in the final result.) Final results. ° Indianapolis union depot: HUTS HAGLER ON AMON =e seca wc cecicle caece cease ee = HOO AG Setseeinesmsicseis cieelctasehtehe te nats Second determination ..255.0.5---4¢-<2--+2ss-ene TRO TDI roca wies se cteotycia syeia eloraeerekid | eieereeetoee Saves EAE AAG PALEC LAT ee aaa src eres wiata aiote oi cin eralela/opah ote] simce ltctel gate! eibreren sts ve joer aioe) ajalointe ao niece age 721, 75 City-base Indianapolis is L. W.in White River.....-- 33.08 | Below union depot . ..--.-|.--...-.-- IRS OLIS CLLVEUARO MEER emai ce acdeld.-caciciesisnsee el saeseen sas |pascmascemeates -asisememei sar 688. 67 646 = GEOLOGICAL SURVEY OF THE TERRITORIES. ELEVATION OF THE SAINT LOUIS DIRECTRIX. O42 aaa qa i Ag gq Feet. Various datum-planes. Sree BES BS3s 2 aad e2} First determination. Indianapolis union depot track .-.. :----+----+ +--+ 2+-|oe-2 02-20 e] eee nee ester teeter eee 1999° 721. 75 Terre Haute, by T. H.andInd.R.R...-...-.--.--- e---| 217.00 Below auton depot Indian- |.......... apolis. Terre Haute, T. H. & Ind. depot ......-.--------+-2---|see--- 22 -| e202 2 een eee eee eee ee - 804. 75 Terre Haute, H. W.in Wabash River .-...-.-..------ 1983) Below) depote rss snes see ees pee eee sane sobossdooonee odd005 sean so caugERcosbanesbdllocooccouss|laseeoo cose sa sogcoousooSoboSe 485. 45 Terre lates river-bed Wabash River.....------..--- 5058.) | Below depotite-seacee sees |aeeeee eee IDX) 3 GES BREE A RARE an eee Oe RSS Aaa Ga RaOCrcdd Mearcasoos psecdoneouoncoaaadaocoUAGabe 453. 95 ‘Terre Haute, ordinary, water Wabash River -. 25.2): 2.|5222- 225-2 |scn----5- ons c eee ee esos 467. 45 Saint Louis directrix; by St. L. V.& T. H.R. R..--- =. 71.60 | Below Terre Haute depot.|.--..--.-- Saint SOUS direc brie ke O02 ere EPA TINUE ett ol 0a RO eR ne Ena 433.15 Second determination. indignapolisumionidepotieesesssasseeeoes cers cee sees sen cree en Geer ease reece eee eee 721.75 Vincennes, by Ind. & V.R.R...-.... ...---..-------. 287. 36 Bela Indianapolis union |.-.-.-...: epot. BVATACON TOS ee aaa esis Sia aisha S wists eteiatiare Bieie ale fave ete otecrall a Sie Seat te eins tedege eterate nate a alee neonate jet 434, 39 Sant Louis directrix, by C. & V. and St.L.&8.E.|- 3.60 | Below Vincennes ..-......|--------- c 8. HaintelLouis aire chris wees Nace caieclcel cece cece ee cies | ne elem Mee eee teen eee eee ee ee eee 430. 79 Third determination. Cincinnati directring sete ae sen coe ceeeeecon lee oe Seek ec eaceeeneee ep eerne emanteceee 339. 74 Present depot of O. & M. R. R., by city- engineer .....- 54.94 | Above city-directrix -.....|----.----- Vincennes, by 0. & M. RB. R. report i nee nan 68.00 | Below O. & M. Cincinnati |...-...-.. (It is not known whether the present depot is referred depot. : to in this old profile. If not the present one, it is probably the one at the north edge of the city, which is a few feet higher. Assuming it to be the same depot as at present: ) BVA COTIM OS ee SA Ca Nihal ci ik NS SS Sy eA 2 eS ee me 326. 68 (On account of the uncertainty above mentioned, this . result is not used, but merely introduced to show how small the probable error is of the elevations of Indianapolis, and Vincennes as determined through Indianapolis.) Fourth determination. Chicago directrix eee eee ese oie erecta Secioe ema tice ere stunted | re aie eee eiatereta tee ee 587. 15 | Effingham, by Ul. Cent. R. R., (Chicago branch,) re- 10.50 | Above Chicago directrix.-.]---..-.-.- ported to me by chief engineer, October, 1873. Saint Louis directrix, by St. L. V. & T. H. B.R..-.-..- 170.80 | Below Effingham .........|.--.----- iB Sainb Moulsidirec brie eee) ome oe er Lis LVS ehh elle Nata ny | PUR INI a oe Rea a 426. 85 : Fifth determination. Chicacosdire chris soho ee PN OG ae A IES IN) aaah te Nn | 587.15 Mendota, (Ill. C. R. R. crossing,) by C.B Cae R.R....! 169.07 | Above Chicago directrix. .|.---.---.- Vandalia, (exact crossing of St. L. V.& T. H. R. R.,) 249,00 | Below Mendota ..........-|---------- y Saint Louis directrix, by St. L. V.& T.H.R.R -.....- 83.6 | Below Vandalia...........|.--.---.-- Saint ont tdirecerixe vb: ote ne) PuGwny c saei Alig daa lL ni 9 anes ae eI Im Te 423, 62 Sixth determination. H. W. 1858, Columbus, Ky., by N. 0. J. & Gt. N., M.C., 320. 01 |, Above M. T. New Orleans.|.----..--. M. & T., "M. & L., N. & N.W.R. Bs. to Hickman, thence fourteen miles by river-slope. EEW 1 644 Sprobablypeeeaey oeeneccr cee ace eeeeeecee SLO AM |Past Cl Pee m Er ara Soran Saalloaaooriasco Saint Louis directrix, by St. EL. & I. M.R.R.---2.-..-.- 100.3 | Above end of track at |.--..-.... (Belmont depot is certainly not below H. W. at Co- Belmont. jomus, on the opposite side of the Mississippi iver :) Hence by this route the Saint Louis directrix could |..........|....---.-.------e-e--eeee-- 419, 41 not be less than. Seventh determination. Memphis, H. W.., city-base + 100 feet.........-......- 218.65 | Above M. T. New Orleans.|-.----.---- Argenta, (opposite Little Rock,) by M.& L. R. BR. R.. 86.00 | Above city-datum + 100 |.......... feet. GARDNER. | GEOGRAPHY—ELEVATION OF DATUM-POINTS. ELEVATION OF THE SAINT LOUIS DIRECTRIX--Continued. Bee ER] Aas _ = — Feet. Various datum-planes. a aa 2 Boda Sros Bseos or Ss iS] ao ATEN docs conscnce Ce bapeoC or scoeouceoonedbanuonese|lUoseradoudlascuseoooeocencecduase tHosed 304, 65 Saint Louis directrix, by C.& F. and St. L. & Q. M. 119.00 | Above Little Rock........).......... R. Rs. (Assuming that the tracks are same height on both sides of the river at Little Rock:) Sain bre OUIS| OITOC brie aa alanis sets Sram stores ects ta eects zee camaro lieahae ois ote sale stows we cise Sosmceic 423, 65 Eighth determination. Cairo city-datum, ordinary L. W .-.-..------------.--- 291.13 | Above New Orleans M. T.].......... Carmi, by C. & V.R. R. and city-engineer..----..----. 123.70 | Above Cairo city-datum --|.......... Saint Louis directrix, by St. L. &S. E.R. R...-..----.- 12D A None) Cerarint Jose 4e ese ceclogodsesdee Same (Ouis GiPeCtEER: .soasen acces ncmee cscs siecan cise a sleoesie eae Above New Orleans M. T.} 427. 0B ! Ninth determination. is | Cairo H. W.,by M. & O. R.R., preliminary line ...-.-- 318.30 | Above M. T. Mobile Bay..!.......... Saint Lonis directrix, by C.& V. and St. L. &S. E: R. Rs 93.4 | Above H. W. Cairo........ [eu ies STE ILA ClO EXO Hibs aan sae HBB OrOGe See GOR S EUs © DAO Ste PAO ase ERE CAR ees One ie ar area. 411. 70 Saint Louis directrix, by Ill. Cent. to Vandalia, thence SGNGmeAtbovierC anova Wieeseeees seen eee by St. L. & T. H.R. Rs. i Sainipleouiss Ine Ct Linea. .taa tet ont seer e ect eee anon meson | cace esasos dodanotcomspogucaconas||secsoqaene Colomnclo Susi) 5 os og booosonsupaodederooudooooasesas 789.0 | Above Denver K. P. depot.|...-.-.--- IO Grmny Ee, IDSIEE Wace 128 012) Kel S saneonaopeasasr an omDUedcda baaHoo dees |loassdoecasaoaacosaoonsodaoos 5, 196. 58 Colorado Springs depo te esse soe Sees ere se orto eee eisteons | PEE ee ee eer ete eee 5, 985. 58 Colorado Springs Hotel floor, by report of Mr. EH. S. 826. 67 | Above Denver K. P. depot. Nettleton, C. E. Colorado Sprin SSvTOtel Moor As ces ace an sees) eee scene ester [ne cio ee tae eel ee ee Ee eters 6, 023. 85 Rock basin of Manitou Spring, by levels from rail- | 1,153.32 | Above Denver K. P. depot. road-bench, by E.8. Nettleton, C. E. Rock basin of Manitou SPIN Bs eee Ne Wee Se Me ay SAL SR oat AT aa 6, 296. 92 ELEVATION OF PIKEH’S PEAK. Iam greatly indebted to Mr. E. 8. Nettleton, civil engineer, for a re- port dated June 29, 1874, of a line of levels which he has just run from aD. & Rh. G. R. W. bench at Colorado Springs to the exact summit of Pike’s Peak. The line was run on the request of Gen. Albert J. Meyer, Chief Signal-Officer, U.S. A., and at the expense of the War Depart- ment, for determining the elevation of the United States Signal-Office meteorological station, which is situated on the summit of the peak. Bh2 one Bas oO Feet. Various datum-planes. | ¢5., . 2 o.a8 So S co) ict{o) R Exact highest rock on Pike’s Peak....-....---------- 8,950.1 | Above Denver K. P. depot.!..-...--.- LOOSE HOFE CORED EEE Se HOSA CR Shona peneRan OSD enor saaureacodlocobescecausmansadossudaeds 14, 146. 68 ELEVATION OF Mount LINCOLN AND FAIRPLAY. The D. & 8S. P. R. R. having run a line of levels for the final location of their railroad up to Fairplay, we secured the services of their engi- neer to continue the line to the summit of Mount Lincoln, at the expense of our survey. The object of this was to determine the exact elevation of our barometric station situated near the top of the peak. The fol- lowing are the results of this line of railroad levels: GEOGRAPHY—ELEVATION OF DATUM-POINTS. op) Or On GARDNER. | SHe Sag =| io ASS Feet. Various datum-planes. eines. aoe BSoeo crs) aa Overnmrer (GD), 12s. es, US, JED) GTO oo coomosnedoed adgoomeose seascogeer|Cononencadondemeesccdeaseasns Door-sill of Sentinel office Fairplay OMe sae seas SS Ase ROSE CS ISR OSE OS SA Ee acne Is aerate petal eet eee Op) Oe, 2 ie Ba eee Cistern of Mount Lincoln barometer ..-....----..----- 8, 991.05 | Above Denver depot..-...|... Let ap 8 DY) seccne see ss eqn nescecoocesnesccossaucsnsecss| pecs econd||s usecosanseegsceos spor osence 14, 187. 63 Summit of Mount Lincoln..........-.-.-------.-----. 9, 100. 08 | Above Denver depot......|...-....-. AD) OS eee ase aE ae Se ia AS eet Wo cisaills |e saw asasidseinngageceas ee eouen 14, 296. 66 ELEVATION OF POINTS ON THE OHIO RIVER. Lins Ral, WANN CED MRCS conce poocod she seoecesen loots obo spa|losooonboomreccenesessocecter 746. 00 eaitebureh, Ibe NE Gi AGENTS Cos eoe Saghosonoeecoscece 46.80 | Below Union depot track .|......---- D conedhesecsc ssh oosossccsossacsecse scone cosoecoeccassugedleosmasbacecoocsbosceaoserene 699. 20 IPAS) Tameel, TELL WYRE P saeco cea cocesnnesesocdasSscosou)lboosonaess||shodoneccacancucseccseseeous 729. 88 Tet Higlpmbred a, IEE, W/o EBPs 3 kas ore doc anon cous oceasno s6sellbonocedonElssoboe becocosaoe sodood eabbnc 732. 95 (These data are from report of city engineer, March ~ 15, 1871.) Steubenville P. C. & St. L. R.R. depot track, by P. 14.74 | Below Pittsburgh depot. ..|.----..... C. & St. L. R. R. ; Steubenville depot, P.C. & St. L. R. R...-.-- apt enaesia lee este eista | eticme nace an ncacs nse atee 731. 26 Steubenville, L. W. in Ohio, by old P. & 8. R.B-...-.-- 68.43 | Below L. W. in Ohio at |-.-....-.. ; Pittsburgh. Stenbenvillewilr-awWi. 1m Obioy eee eerie ste ail Saieniaruare lisicps cciiac wa caseedee cee 630. '77 Steubenville, about H. W.1852, by C.& P.R.R..-.--- 103.55 | Above Cleveland directrix]..-...-... 0) dense seeeeu 2 nonede nocssdoscees cee se sossesaalle coecoenoe||ssaccsecosescaceooueetoneanc 679. 23 Bridgeport, about H. W. 1852, by C. & P.R.R....-.- 96.55 | Above Cleveland directrix|....--.--- Leesa, MWOUUH EL WB = =o Soocee roocoe ole'<[e in -iaeicinis « simsis(ale sincisicke cielo e BACT ooososooos 467. 45 ROLLORMAMCO De CA ied OAS Deb Viele somata iaial= cise aintenmisiatsecreeraiaeeceeeiee SOP Ci cesar cee 453. 95 FRET CERRIUVOLS eMeLU LOG) eamecmiee ae ce eiaser cssaasa cio ssisiciasecne sce etese cee Canada ..-....... 15. 00 WMincenmes pind coVenkt. hi. CEPOu UEACKese cee etece je cme saein cee cecesec ase nee in dianayseeseeeee 434. 39 WATICeNES EH AWD WidbashvRivien somersiscecese cece ccs nasenscceccebicee Hh GOMa Same Seasce 425, 39 Wancennes phi Wain Wabash i RIVeDesenc misses sine ne sancineesiciciee eeieeeue 2200 scosenssseo 412, 39 Vandalia, junction of track of St. L. V. & T.H. &T.C.R.R...........-- Mlinois .......... 511. 89 ¥ cry ra Tie eee prieray Ty, % > aE wae’ thee rhe’ PT ad pny Bioware? : 1 ohana gar ane ian Aare a snciaginid seared oP we eaettor= ~_ wan sp ‘i 10% Ob er BAVLIO“? Gan PALER) sv MD CVT TIME? | oat ee wk yt a ; eee —_ eierahenes at it ' t i 1 } te ; } 9) | \ } |, oe \ 5 ——————— * \ ae ey ae +) | ye: ——— nar anne eens SCAG sa te ENS FWA a ps GEOGRAPHER. ae The circles indicate places #/ MAP SHOWING THE which the eleratearaare gira ix tha tart USED IN THE DETERMINATION OF ELEVATIONS Nore JAMES T. GARDNER voces sista Satis elelacier(scine doincisiealseee @snewees t 14,176 Massive Mountain, Sawatch Ramge....-:..--.....-..-.-.----------------- t 14, 368 Mount eH lbert SanvabehwvanlG@)j- an. ass sc) el jaiainie cioetel sine elotelelo sieioe sia a 14, 326 La Plata Mountain, Sawatch Range...---..---..-- Sea aia cee eae ltae see elslsls aie 14, 302 Mount Hanvard,-Sawatch Range). 2254.2 sssdes+ secs ossaclce ses seen ssee 14, 384 Mount pYaletsawatch hance sacs a1 ve joie snes) slate ts % “6 t ¥ j G 4 ; f im Je tela . ; eae a ut nee y APPENDIX. + OR 14 al ea ; a ‘Sarny side -/7 =i y Ae an ; Ward. \ j District —\. x : #7 Americus Bil t \ xz i a { tS) pet Gold Hill ae: ( (RB cd Cloud te. |) Base of the ———>_—. \ MAP. _ Showing Ihe postition of the |N \\ Gold Hill Mining Region, 2anile: to at inch GOLD HILL MINING-REGION: ITS POSITION AND GENERAL GEOLOGY. By ArcH. R. MARvVINE.* The accompanying map has been prepared to show the general out- lines of the country in the neighborhood of the Gold Hill and Ward mining-districts, in the mountains of Colorado, while the following remarks explain briefly the position of the region in relation to the surrounding country, as well as its general geology, as determined dur- ing the explorations of the summer of 1873. Nearly parallel with, and a few miles west of, the western border of the country represented on the map, rises the main continental “divide” in a north-and-south crest, which here reaches an altitude of nearly 13,000 feet above the sea-level. From the base of the main crest, a zone of mountainous country extends eastward, which is cut through by the streams in a general east-and-west direction. The intervening ridges are not sharp, but of a massive character, often with undulating surfaces, their higher points usually reaching in general a pretty uniform level, the ruggedness of the country being produced by the deep cations of the stream. It is a portion of this region that is represented on the map. At the east (near the border of the map) the region abruptly ends along a nearly north-and-south line, the massive spurs falling te the zoue of “hog-backs,” or-ridges of upturned sedimentary rocks, which lie all along the base of the range. The “red beds,” probably of Triassic age, form the innermost ridge, lying directly on the Archean rocks of the mountains. These, in going eastward, are followed by the upturned edges of Jurassic shales, the Cretaceous groups, and the great Lignitic formation, of as yet disputed Cretaceous or Hovene age, which stretches eastward, and forms the beds directly underlying the great plains. Boulder City is on the border between the mountains and plains, and is reached by railroad, Denver City being but twenty-five miles to the south and east. From Boulder City, wagon-roads up the various caions give access to the mines in the mountains. South of the region repre- sented on the map, from fifteen to twenty miles, is Clear Creek, much like the Boulder in general character, on the tributaries of which the better known mining-regions of Georgetown, Idaho, Empire, Black Hawk, and Central City are situated. : The rocks of the mountains, as a whole, may be considered as being composed of a great series of metamorphic rocks of Presilurian age. Quartzites, siliceous, micaceous, some hornblendic and garnetiferous *The following notes were originally prepared to accompany an article of Prof. ’ Benjamin Silliman, jr., in the July number of the American Journal of Science, on the telluride ores of Colorado. They should have been printed with Mr. Marvine’s report, but were accidentally omitted; but as they refer to the area occupied by the survey, and should form a por- tion of the report proper, it seems advisable to print them in this connection. 686 GEOLOGICAL SURVEY OF THE TERRITORIES. schists, gneisses, and granites, all occur; the gneiss, with possibly gran- - ite, in the greater proportion. While large areas of structureless gran- ite abound, apparently of so-called plutonic or eruptive origin, search seldom fails in finding spots or areas more or less large of gneissic or even distinct schistose structure. The fact that these usually merge im- perceptibly into the surrounding granite, as well as conform in their strikes and dips to the general system of folds, as more plainly indicated perhaps in adjacent schistose regions, show that such granites have been metamophosed in situ, and are indigenous rocks. At the same © time, sharp lines of demarkation, and the occurrence of dikes and allied features, show that the conditions of extreme metamorphism have prob- ably been accompanied by a great softening of the rock, allowing ready molecular re-arrangement into structureless forms, and producing plu- tonic and other appearances indicative of an exotic character. The same granite mass, approached from opposite sides, might convey entirely different impressions as to its origin ; a metamorphic indigenous nature being indicated upon the one hand; an eruptive, exotic origin upon the other. I doubt if any of the large granite masses of the mountains are of true intrusive character, and even if those ‘smaller ones which are clearly intrusive have come from great distances below, or are other than of the same Series of rocks melted by the heat accompanying the metamorphism of the mass. Along the south side of the map, and exposed by the cafion of the Boulder Creek, are massive gray granites, with but few points where any structure was observed. _ All along this half of the map, the general strike is approximately east and west, with a northern dip. Thisis the case also along its west border. Near the north and east sides, however, the dip is south, indicating a synelinal structure running through the middle of the eastern portion of the map. A horizon in which a definite schistose structure tends to occur is in- dicated by the dotted area running through the center of the map. Some of the rocks here are distinct schists, but little changed, and include very irregular red and black banded _mica-schists, garnetiferous, and some handsome, fine, and evenly-banded, gray gneissic schists. In places, this zone may be lost in granite, but opportunity did not offer to care- fully follow it throughout. Most of the granite on the north edge of the map contains little if any mica, tending to a reddish granular aplyte. The schist zone shows the fold of the formation very well, some of them being very abrupt, and regions of great contortion. All the observed strikes and dips are in- dicated on the map, but the general structure of so small an area cannot be well shown separated from the surrounding country. These schists and granites are pierced at many points by a number of dikes of felsite porphyry, which are also indicated on the map. Usually these form hills or ridges, and while some are quite long, the porphyry has apparently often found vent through less extended openings, now showing as sugar-loaf-formed hills, without the direction of the dike be- ing clearly indicated. Such forms are shown by a cross. The porphy- ries vary considerably in character, but no careful comparative examin- ation of them has yet been made. Some contain remarkably handsome erystals of feldspar, often of the form of the Carlsbad twins. The tellurium ores of Gold Hill occur in connection with one of these dikes, (see section beyond.) This dike varies from 45 to 35 feet in width, trends about north 30° east, and dips approximately 80° to the north. MARTENE:| GOLD HILL MINING-REGION. 687 west. On the east side is the Red Cloud; on the west, the Cold Spring mines. The former, upon a casual examination, showed a well-defined hanging-wall, or that on the side of the porphyry, a vein usually three or four feet in width, but in places pinching out to a few inches, with at one point a clay-like “gouge,” and an indefinite foot-wall on the side of the coarse gneissic granite, which is here the country-rock. Some of the vein-matter appeared as if a decomposed granite, while the pyrite is the most frequently occurring mineral in the dull quartzose gangue of ' the vein. THE TELLURIDE ORES OF THE RED CLOUD AND COLD SPRING MINES, GOLD HILL. By B. SmuimMan.* In May, 1873, I briefly announced the discovery of tellurium gold-ores at the Red Cloud mine in Colorado, and stated that Prof. N. P. Hill, of _ Black Hawk, had proposed to send me specimens of these ores.t The specimens sent by Professor Hill were long in reaching me, and it is only recently that I have examined them. The observations made in the summer of 1873 by the officers of Dr. Hayden’s expedition have sup- plied the data needful to understand the mode of occurrence of these ores, for the details of which reference is made to Mr. Marvine's notes and map, which form part of this paper. It appears from them, in general, that near the mining- faaaler of Gold Hill, about twenty-five miles northwest of Denver City, and at an ele- vation of almost 8,000 feet above tide, is a wide dike of porphyry cut- ting the metamorphic rocks, probably of Archean age, about six miles west of where the Triassic rocks die out at the base of the mountains. AC CES E NRE A section of this dike, A, furnished goSre 22% by Mr. Marvine, is annexed, showing eee Aap the tellurium-bearing veins B and C Haege) so. SG on its sides. The porphyry of which AW che it is composed has distinct erystals of Sl ead feldspar implanted in a purplish-gray iy fir be paste. These crystals have a green- IN, Re eee B, C, veins with gold ish-white color, and are evidently and tellurium-ores. partly decomposed. As seen ina mi- croscopic section, it shows the usual obscurely crystalline ground-mass of felsite, with crystals of quartz, and sections of feldspar crystals show- ing the parallel bands of a triclinic species. A glance at the map shows the position and course of this dike, and also the existence of other dikes of porphyry in the same region. The porphyry from the “7.30” and ‘‘ Central” mines closely resembles that from the ‘ Red Cloud,” while that from a dike (No. 136) between the ‘‘7.30” and the ‘‘ Americus” is distinetly trachytic, and that from the “‘ Niwot” mine, at the west margin of the map, (No. 181,) is a quartz-porphyry, with distinct crystals of biaxial mica. Those ‘from the dikes at Jim Town, (specimens No. 147,) on the north border of the district, are distinct sanadin-trachyte. The tellurium-ores have been explored so far only in connection with the dike near Gold Hill, shown in the section, although they exist with the dike at “7.30” and the ‘ Central.” These ores are found along the * The substance of the following remarks was originally communicated at the April session (1874) of the National Academy of Sciences at Washington, and afterward appeared in the form of an article entitled “‘ Mineralogical Notes; Tellurium Ores in ~ Colorado; by B. Silliman,” in the American Journal of Science and Arts for July, 1874, and from which they are now here reproduced by the permission of the author. It was in connection with this article that the preceding notes on the general geology of the region about Gold Hill were prepared and approved. + American Journal of Science and Arts, III, vol. V, 286. SILLIMAN. ] TELLURIDE ORES. 689 line of contact of the walls of the dike, in a quartz gangue, associated chiefly with pyrite in small, brilliant, highly-modified crystals, andrarely with chalcopyrite and sphalerite. Professor Hill speaks (loc. cit.) of lead ; but I have found no salts of this metal in the specimens received. The quartz is chiefly hornstone and uncrystalline quartz, and, on the side of the country-rock, it is mixed with feldspar. Native gold is not visible in any of the specimens I have seen of this ore from below the surface; but where the surface is weathered, it exhibits free gold, arising from the decomposition of the tellurets. On the sides of the dike, the line of division is clearly defined, but not so on the side adjacent to the metamorphic rocks, it blending on this side with the granitic materials. The thickness of the veins varies from four or six feet to a few inches, but the rich tellurium-ores form a com- paratively narrow seam near the center of the vein. The Red Cloud mine, which is found on the under side of the dike, has been explored to a depth of about 70 feet. The Cold Spring mine is explored on the upper side of the dike. The tellurium-ores are not found in the body of the dike, but have (owing probably to the long-continued high tempera- ture of the dike) found lodgment in the granite outside of the walls, and not in immediate contact with them. The species at the Red Cloud mine are native tellurium sylvanite and hessite, (which has been called petzite.) The simplicity of the mineral- ogy of this locality is in strong contrast with what is found in the tel- lurium-veins of Transylvania, which are mentioned more particularly farther on. : Native tellurium.—The occurrence of this rare species in the United States, in California, was mentioned by Dr. Genth, with a query, in his Contributions to Mineralogy, No. vii, (American Journal of Science, IT, xlv, 313.) Its existence in the Red Cloud mine is unequivocal. It was simultaneously, yet independently, detected by Dr. Endlich and myself in a small specimen from the collection made at the mine last summer, and now forming part of the Smithsonian collection in Wash- ington. It did not exist in the collection of those ores sent to me by Professor Hill. The hexagonal cleavages are perfect, and one small and very perfect crystal was found, which has been measured by Mr. E.S. Dana. Its reactions before the blow-pipe are perfectly in accord- ance with those of the species. It contains no selenium and only a trace of gold. Auriferous hessite—This mineral has been spoken of as petzite ; but it contains much too little gold for this latter species.* Its specific gravity is 8.6; luster splendent when freshly broken; fracture conchoi- dal, brittle, but somewhat malleable; under the pestle laminates into thin scales, and is with difficulty reduced to fine powder, leaving on the agate surfaces metallic streaks of plumbago-like color. Color telluric, tarnishes blackish on exposure, sometimes irridescent. Cleavage none. Before the blow-pipe in the closed tube, the pure mineral (with no trace of pyrite) decrepitates, fuses to a globule adhering to the glass, and exhales a white sublimate, fusing into clear, colorless globules. Alone on coal, in both flames, it gives a globule, coats the coal with the characteristic areola of tellurium and tellurous acid; it does not exhale any odor of selenium, nor show any trace of lead. The globule is non- magnetic if pyrite is absent, and does not vegetate with silver as hes- site does with soda; it gives a large bead of silver, which dissolves in nitric acid, leaving gold in powder. ius EM OeinN AWE AMMO Td BY fo yee a No ea eee *Mr. A. Hilers, M. E., in a notice of the Red Cloud mine, in the Transactions of the American Institute of Mining Engineers, vol. i, p. 315, considers it petzite. 44 GS 690 GEOLOGICAL SURVEY: OF THE TERRITORIES. Cupellation gave, gold, 4.40 per cent.; and silver, 50.90 per cent. By a partial analysis I found, inthe wet way, gold, 7.131; silver, 51.061 per cent. Understanding from Dr. Genth that he is engaged in the chemical investigation of this species, as well as of the other tellurium minerals of the Red Cloud mine, with abundant material, I have will- ingly abandoned this work to him, satisfied that it cannot be in better hands. Sylvanite.—This species from the Red Cloud mine yields i in the open tube a faint odor of selenium, and the gray ring of tellurium is preceded by a slight reddish ring of selenium. In the closed tube, the ring of tellu- rium is more distinct, and the deep yellow-brown vapor of the oe is ‘clearly seen, but the ‘selenium is not evident. Alone on the coal it fuses with exhalation of the odor of sialerniGon and ‘its well-characterized blue flame. The first touch of the outer flame ‘causes a liquid fusion, coating the coal, like argentic nitrate, with a ‘silver film, and a yellow areola appears before the white film of tellu- rium-oxide. Continuous flaming in the reducing-flame produees a well- marked yellow-brown areola within the tellurium-ring, becoming, as it ‘cools, much more brown. It probably contains lead and antimony. Its reactions are not those given by Berzelius for sylvanite. It contains by ‘assay gold and silver in the proportion 1.7 to 1. In the formula, (Au 28.5, Ag 15.7,) the ratio of the gold and silver is1.8:1. My stock of this species was not sufficient to permit a determination of the specific ‘gravity. Protessor Hill, who has smelted large quantities of the ores of the Red Cloud mine, informs me that “these minerals exist in this ore as minute particles, or so finely divided as to produce the effect of a stain in the rock. One of the specimens sent—the darkest colored—assayed here was found to contain 1,890 ounces of gold and 5,300 ounces of silver to the ton of 2,000 pounds”—about $50,000 in value. Comparing what is known of the mineral associates of the tellurium- ores of Colorado with those of Transylvania, as described by von Cotta, the great simplicity of the mineralogy of the Colorado veins becomes very conspicuous. The age of the ‘porphyry-dikes which cut the Ar- cheean rocks of Colorado has not been determined; but it is probable that they are more recent than the Triassic rocks which flank the base of the mountains. The tellurium-veins of Offenbanya are accompanied by igneous rocks of more recent date than the Hocene sandstones, and. those of Nagyag exist only in connection with igneous rocks, also of probable Hocene age, (called by von Hingenau ‘ ereenstone- porphyry,”) ‘and composed of feldspar and amphibole, which have broken through sandstone and argillaceous shales. In Offenbanya, the tellurium-ores occur under very peculiar g -geologi- cal conditions ; that is, in veins in igneous rocks and in segregated masses in granular limestone. The veins occupy thin clefts, fifteen of which on one property are tolerably parallel to each other, (east and west, dip 30°-40° north,) with an average width of about an inch, and they carry chiefly sylvanite, and nagy avite, sparingly distributed, and more rarely native gold. The chief matrix is quartz and diallogite, as- sociated with py rite, eV, sphalerite, stibnite, native silver, and pyrargyrite. The gangue of the Nagyag lodes is diallogite, or brown spar, or cal- cite, or hornstone and quartz; it varying in the different lodes and in different parts of the same lode. The gold-bearing tellurium-ores are scattered through this gangue with mangan-blende and pyrite. The chief ores worked are nagyagite, sylvanite, gold, auriferous iron pyrites, SILLIMAN. ] TELLURIDE ORES. 691 argentiferous tetrahedrite, native silver, and galenite. Associated with these are hessite, bournonite, jamesonite, barite, sphalerite, stibnite, native arsenic, realgar, orpiment, silver-glance, chalcopyrite, marcasite, native copper, malachite, pyrrhotite, sulphur, &c., with various epigene species. In all, over forty mineral species are enumerated as found in’ the veins of Nagyag. Compared with this abundance, we find at the Red Cloud mine only native tellurium, sylvanite, hessite, pyrite, chal- copyrite, and more rarely galenite and sphalerite, with native gold and an epigene species at surface. The gangue-stone is hornstone or chalce- donic quartz, with feldspar. Possibly explorations at greater depths may develop other species, but this result has not followed the deep-workings of the silver-mines in Nevada, where, at the depth of 1,500 feet, the number of species found is not greater than it was at the surface. A like paucity of species characterizes the metamorphic and volcanic rocks of the Sierra Nevada in California. Due cn Bee Sk Met Ne GENERAL INDEX. Note.—For alphabetical lists of minerals and rocks, (not repeated in the following,) see pp. 267, 270, and 356; for list of elevations, pp. 657-659. A. Page. Netinolites.+-cesese ce gsesotr ase 265, 267 Acate -.----..- seanocossooabnsce 267, 269 Alabandite ...--. apooec Bs Ae Blaise 267 Alluvial deposits ....-----.------. 350 INTE UOMO ac coon scocso acobsScocoses 287 Amazon stone ...-.......2.....--. 268 AIMenIGAS MINOastecisatest setae sae = 303 ANTI@WIVINE coocob os0cn6 coco os500065 267 JNSTTTOIIESS 5 Sanco boon DoDbOD CobaSane 26 MTA TWO O s.Sdcsoasneces coeSeasne 267, 268 Analyses of western lignitic coals. 112, 114 Anim lesitesaciiccios tose ss sn'ecesicetis = 267 AMT GLAD Soeeous CoUOnD DonbED GoD> 267 Anna and Washington lode....-.... 305 Anticlinal ridges 9---<-.----.-2.--- 19,79 Aqueo-igneous fusion .......--.-.- 142 Arapahoe Peak ..-..86, 87, 90, 150, 152, We AT CHAN AOA 25 25 oc aeeistedsic ie tees 146 rocks, 93, 96, 98, 138, 139, 146, 155, 156 AreentineyPass .<222/stss-22 <6 -2- 88 ATER OUTS) Sag daoa Boondsees Gooo dead 267 Arizona, Northern ..-.-..--.--.---- 1388 Arkansas\ Cation). 2...<.+0o-25 254 5- 240 MAL Giese ace ceeericissic ee 49, 240 Parkerae sss oueeoee 50 PRUVOT eer). wate ote clociets 48, 239, 307 sandstone....---------- 312, 326 iValleyraesc =. 48, 50, 59, 239, 304 ATSCNOPYTLC sei cclai- cece ecitabeeee 267 Asphaltum spring ..-...--...----- 101 AMT@INOOA, WONT ooee5 Hnoosl sob6as 86 AG UT GO Sie/sicic' 290 142, "153, 154, 157, Saco.cccctokee eee ease! 296 | Middle Park division...-..-..----. 85 Saint Louis........+.-.-...- 305 | Middle Saint Vrain’s Creek....-...- 151 Senator. ccs. seesetieees ' 333 | Mineral deposits, sec. c, San Luis.. 345 Seven-thirty........ »----- 001, 353 |: Land Company.-..--..---- 125 Silver ming fae vee sectsts cee 305 spring, Canyon City-.-..--.. 317 | Slater eee tee dees 302 | Mineralogical notes....--..--.----- 304 SUpPevior. asic ed ace ee 305 | Minerals, catalogue of, for South Tempesti eee ee es 305 Park district ........- 267 Terriblew ie yas e uasseisd psisey | (297 catalogue of, for Colorado - Wincley Same s ee ee eee eee OUS MELTitOnwy.acieiee eee Ol GENERAL INDEX. Page Mane Aniericusas 232252225252 Se. 353 Bakersrarehoseses 522 2st 7. 298, 303 Bobtarthssseso sess rsssereskes 285 Coldisprineee===seeeeece 302 Bik Moumiams) 2c eee oe 259 Binte: sree cesesn teeters 121 Gehrune’s'coal- soos. --52- 202 Gent Stoo eee 333 Gilpinwe ees ess oee sete 127 Gotdem City ess. 2-sseeee se 25 Grand Army sos. 2 a 288 POLSON e Ses ARE Soe se 2G VJOWESE SS fonee ses sets keene | 127 ovetmdlsnssas ss errs oe) ake 125 Warshat=sss- sss ssehoo hose E on Marshall & Mur phy Sanooqise 120 Mekassacks <2: 233 ssscee: 121 Monte Cristo ..--...-.- 288 292, 293 NOOR Giana aceimerietoercciacerice 41, 303 Mount iiimeoine sss. eo 225 Riattete= ssschrst css tee 121 Rosittatssss)ssrssoorss Sehess 333 IOWerst 2282 sare. anes eee 127 Starsesascs pense bee ee 296 Steven & Leviathan:-:---.-. 333 Rerribles s=seeeei ee ES 148,149 Union* Bark: 32225272252 eke 246 Welsh & Loveland .--.-...-: 126 Pa Wilsonvss saree Oa Se 127 Mines in Elk Mountains....-...... 259 Wiiirin SFOMICHES is str ts oe eee 42 report, Dr. Endlich’s ....-. 276 LSPOLb; Drew eale sia = 2s — 301 HOLINS So sais Moose see eese 76 Wioceneibedsesasssc= essa esesee ee 93 PETiOUUe ers eer eters eee 32 e SEC Grane hiisessss) = eee 341 Monte Cristo mine.-..-.-2:-- 288, 292, 293 Moose Mine tzf2\st225522 22552 S222 52 41, 302 Montezuma 2222222522 S2sses sen" 88 WECM OTIETA/ Sees cousco Hones Goce 225, 226 Monument Creek ...--...2::- 199, 200, 202 group --.-.---32, 199, 200 Parkssses2223 dsueh 32. 200 Morainal reels: 25:52 22s:t22 22322 56 GESOSUS sacha seaesooct se 56 of Taylor’s Creek 53 Moraines:: 2secticsstciessss ke 240, 246 WMascOubass +s 2s2ee222 222 2uesss. 328 Mosquito gulch.-5::..----:-:- 41, 228, 229 Mother tange>:s2s2 2575 s222225<.2- 51 Mountain-border region, structural featumesofsszs cfs: 2r5r222ss2e35) 18L Mounts, mountains, and peaks: ATM DON 22. See ser sae 86 Bellevue ...--:: Gp 65, 257, 258 Ibersem bankas asses sass tose ae 89 Berthoud Pass’:2sssasesso2e.% 153 AC penne Sains oss wc nets aldicmies 318 BlackyPyramid: 52225. 2522224. - 61, 63 Blue River.......-.. 157, 187, 189, 190 Bowles <:22s52 213 Hoosiers see cue oisisoe aelsele 226 Wed ROCK see ae cetewelereraicre ieee 241 Tennessee.....-.------------ 242 Uy Weston Sie se-n/=3c0 sen e econo Paul, J. Marshall... <.. 25-2. s-2cee)- 43 IPayrockeminersreiselssseleineiseteiett 298 Peak, Bellevue ......---.-..--..--- 65 Black Pyramid .-.......--..-- 61, 63 Buttaloee.. cceee ken eee 50, 237 Capitol. 223. 2.622 ste eee 260-261 Castle sas ease ete 61, 253, 255 Gothiess2seeeermcwcacersees 64 Gray shi eeiccosseeseieae steers 76 Grizighy; sss3 282 Scectereeaeees 239, 241 Dita ltanvsssae ars eso 60, 69, 250 WONgYShesece seca ceeeeee 76 Maroon ene pease es 61, 63 Middlesea eeneseee 78,79 81, 82 Pike’ssce <2) see 34, 194, 204, 205, 304 Snow Mass........-------- 64, 66, 68 SOD od5 Seodboooonspeses 61, 69, 265 MOLrey’si. sis) css Saeaee sy sisisleas 76 Wihiterocky 258. 3s sctsciesee 63 Peale, ALC SoBe Bes bai oe Ma ues 101,115 LEPOLbObss i secrete 193 Peers shaft.....----. Secs seteeses 287 Pelicanvlod esses meeiceecleseaeeieaee 294 Permian fossils ---.-------.----00e- 245 strata, &c..105, 219, 222, 238, 242, 245, 255 Petrified stumps.........----..-.- 210 Phlogopite- 2. 2-2.) 52sec eenine= 269 Phonolithic andesite............--. 346 Pikke/spRealkesepysiepsaietete eiareiseieer 194, 204 ilo tlodesaseiaermisers cisisiccin oeietereiaels 42 Pine Creek) 4ccieis eissieaiseeieisialsicie 240 Pippin shaft........- bd.gog0gca Coad 287 Pitchblendelseserrteseniececeseisiecels 290 Placer diggings..-....-....--..... 304 WMH G5 Sooo bond Seco nSSe 42 Platte Mountain ..-..--.---..-.-- 194, 209 IBIHYEI® a oaoo Osco sosOSo spDOaC 89 Platteville mine...-..--.-..----.-- 121 Pleasant Parki 2.30.2 e eee ene 34 Pliocene deposits.......-.--..--- 49,77, 93 Phum'\Creek 222 3. occas eee 197, 199 Poncho) Passee2esacceeee nce 321 Porphyritic protogine.....-...-..- 337 Porphyry dikes..........--.-- ---. 144 Post-Glacial times... ---- Sy NC 36, 45 Post-Lignitic formations........--. 128 Post-Pliocene deposits--...--.-.--- 17 Post-Tertiary deposits.....--..---. 93 Potsdam group 30, 41, 202, 208, 209, 226, 236 242, 255 sandstone..-..-...-------- 138 Powell wiMay oneseerseccee asl 159, 161, 188 Rowells Mountesceeseeeeeeieeeese 75, 76, 81 Printerboy lode.....--.-.--- Soidcse » 303 IBrize Jodemeaaeeee eter ate ee 288 Procer ill ssseeee ces seers 280 Producer furnace ...--...----..+--. 118 Protogyne, porphyritic.........--- 337 Pulverized fuel, Whepey & Storer. 119 GENERAL INDEX. Quartz eas sccss see shies ceeeeeae 269 UU Sejeoisiayasiciayansemaeeees 280 OQaarbae res ssaoee wee eowsewamae ve 308 Quebec group.-.-...- 202, 208, 226, 229, 236 R. Ralston buttes-ae eee eee oe 89, 152 Creek....- 89, 95, 97, 100, 102, 108, 136, 139 Range, Elk Mountain.........-...-. 250 rOnb es sc cc sce ess asi eset 194, 207 Pan e eee soa ence ae 58, 239 Sawatchesssssceas soseeee cog 246 Raymon Gs Wx sc closets -sjase a 115 ed “bed sis. Ws cea coe ses. Sesh esas 96 iRediCloudiiminesesscc- aan aaeeece 304 HEGUETOUPe oo. cae ses tsa saseeeee Ol, Oe Red)Rock Pass... S225 ssa:0acseece 55 RediStone Creekieassccceseaeeene 22 Report of William G. Binney---.-- 623 W.L. Carpenter. ...... 537, 538 MiwAG Conrad: ssa. 455 Edward D. Cope....-... 427 William H. Edwards.... 542 Even ndlich=sseeeeae 275 Henry Gannett..-....-- James T. Gardner..--. 627, 629 PipA sna cenasanaseeeecs OM Belay Genear aaseme ae 17 SuBybadd ses ssssces-55 66T Leo Lesquereux.......- 365 Arch. R. Marvine.. .... -83, 685 C. R. Ostensacken ...... 61, 567 A.S. Packard, jr. .543, 607, 612, 613 WSC WRCales cece secs 193 BSE Silman esas ea OO S.I. Smith.... . 608 Henry sWilke eases see 567 AVE Vierrill ee aaanieeee 623 epUpIGTOCOs so aic4ec.ncicccncceeeee 302 Republican Hill... ....-2 seneiscne 298 Rhyolite, sec. 1,San Luis .-......- 339 River, Arkansas ........-..--- 48, 239, 305 Beale is i-eic ee eettoee = 89 IDO) Coe bcee nese coca oO. Ve 7b te) Colorado’...22----- 62, 239, 242, 245 Bap leesenen a < 74,78, 239, 242, 245 DEE ionaa beonae 64, 248, 249, 250, 256 AN eAe ce cheeoo badncoeuns 89 Frazer .-81, 87, 90, 166, 168, 173, 180 - Grand... ..78, 79, 81, 86, 90, 166, 168, 169, 173, 180 GICON) « seis casetsiced assess 62 Gunnison).2-5 sees 60, 246, 247, 340 inthe: Platties-saseesseese ee leo Mid diya. 225-26 = tisecince 81, 155, 176 North Fork of Grand ...... 15 North Fork of South Platte.89, 212 iverianiye Ito eee aorea paoege 56 SaimipCharless.:2 2. coe) eee 436, 441 Cleonus trivittatus..-.......--.... 570 Clepsine ornata....-----..----.-.- 623 Dallindageeeer ese eetcreret 623 (CHEMIE s oo5 SoeusdododsodésoGo0ds66 - 569 @lerusispheseusee-seseeeeaeen ee 569 Clisiocampaleceseeiecscciee eerie lar 557 (hintetise Sane bcoo55 Gaoe6s cooded os— 461 DUM cooees coseadasscudcs 461 TOCA sob6 Sogoso5a5ceN s500 461 Cnemidophori -.-.-.-.-....----.-- 514 Coccinella monticola......--...--- 570 JOHOR S5505 65500 deooces 570 transVersogutta .. .539, 541, 570 Coccinelllidarseeerissoee eee eta 539, 570 Coccolaba levigata ....-...---... 387, 388 Ccenonympha ochracea...--..--- Boil) oy Coleoptera eee ee eeeoereeciee aerial 539, 541 Colas Alexandra ...-.....-.-..... 542 Eurytheme .......- G500 6000 * §42 Keewaydin:..-....-.--....- 542 IWigaghis sos obsso0 54606 sooaKC 542 SKOWIOWIGU. GOSS ccaesecocseKee 542 Collopsicruibrosuss- cee eeeeeseceee 541, 569 Coloradia Pandora...-...--.-..--. 557 Colotaxis cristatus....-..----...-- 477 Colymbetes agilis.---......--..--. 568 binotacuseseeee seer 568 GensUSi eee e et 568 quadrimaculatus -.---. 568 Compsemys) {ae esac reece esses 44 WiGiWBscsosscoos coos of bey dM @omploniaes esate eee eee ” 422 LOMO MAT ese eee OCS Gonionfis oval Se ie 569 Conocoryphe....---- sodadsboneacbe 208 Cordulina..... Staats CHM NI Cri 590,.604 Coremia ferrugata.......-....---. Sol Iiontcolorataceneccaseee 55 Cornus aAcuminataseeoosee eee eee 387 FLOlMeSh ee ee 382, 402 TNO LOSS Biss steerer 376, 385, 408 incompleta ......----.---- 382 Orbitera ye saa ee ses 382, 402 Mlaluplyllaeep esses eee 376 | TNEVERMAIMTONNE, S556 ascsus cose 387 Studenieee eae eeaece 382, 385, 402 Worphyramlewlsiieemenescdace eee 570 Corycia vestaliata....-.. PUNO ete 553 Cony daligunnsiaeseeurcerea cers 599, 605, ae Coxnvdallisicornmutayseeee sae 599 Coryluss eee Secret adee 378 HANACWOMIE) 5455 6555 csogeses 387 MecQuarryi -.---.. 385, 386, 387, 388 Corymbites morulus.........-.-.-- 569 HAC HUSarcccascdusoccas 569 Crambus agitatellus.......----.... 548 Carpenterellus .-..-..--.- 548 Ineyansliiey 52 sa heSaa6 Shoe do 948 A IS oe kod S465 doeGee 548 INDEX OF SYSTEMATIC NAMES. Page Cramer s Uy een aie ee a erga 202 C@redmeriairesrctec chistes eee 424 Cremastosaurusia: sss see see eee 51d carinicollis...-..-- 515 unipedalis........- 515 Creophilus villosus ..........--2.- 568 Criocephalus agrestis .-..-..-..-.- 570 Crocodihia ieee Nee 452 @rocodulustsseeemesec eter aeeeeee a all Crocota brevacorniseesa2e-s see eee 559 ferruginOsacece se eesee eee 509 Quinariaye: sees ee ae 5 BBY) Crypiuserobustusssseeee eee eee 541 (ODES GSB EPA SARS Sa aeRR Ses Goren Ts 562 (Oilers sae a eee Gennes Gacose 562 Cupulifere ...-..- sr Nasate sershelaatelseacete 377 Curculiomida eee ee eee eee 538, 570 Cychrus elevatus..-.-.-.-.-..---.. 568 Cyclasises. sees ce Na Ue ee 613 @ymuindisiretioxa yee lessee 568 Cy mips eee ee ace ic Mee ees Ge 567 erimaceng y= 5. Jeuaee sees 567 pegomachoides......------- 567 SINSMIANIS Vee eee ood Cynomys ludovicianus.........:.. 480 Cy peraces:-cie sss ce ee eRe 79 Cy perites\ ee 2 saeo iy ce ee 386 ANOUSHOT eee eee eee 384 iBolcensiseeseseeeee ee 375 DWeucalionis}{ss-4-2-eee 389 Cyperus Braunianus.----.....-.-- 389 chavannesis .......------ 384 COV US en ice rats e 440 (CVs eee eeecuooEeoceonceduaposas, | 44K) C@ytilus' varius sss eee eee es 569 Damphipnoa lichenalis.......--..- 576 Danais archippus ----...-...-.-:.. 542 Daphniays ste -eee eee eee oles OlAMiles pulleks nc ose ce ee 542 Daphnoceneheele sae eee 374 anolicaeeese eae 375, 377, 401 melastomacea ----.--- 375 VieELONeNSIS Hee ee eee odo Daptophilustyaneee= sess see - 508 squalidens ...--.-..2. 508 Dasypoconinaeeee ee eee 562, 563 Dasytes Hudsonicus--.---2-.-.-2-. 569 Decapodaweree sere aseeee BnR ese je Gls) Dechicus 22a se Aes tee cece aisha 541 Devlephilawlineatareaaseseeee eee 559 Delessextantullivae eee eee eee eee 379 incrassata ..---.---.---- 379 lingulatan see eee eee 379 Dendroctonus obesus...---..--.-.541, 569 Dermestes fasciatus.........-.---- 569 Marmoratus 222222 222s 569 TMU See ae eee 569 Dermesticlas~ oye AOA SS a 569 TPE CUTIE Ss 2 foie ies REN SO 514 uinquepedale......_.... 514 unipedale :.2222-.25..-.. 516 Diandra acubilopay ss son. cole esse 374 Dichodontidse eee saeee eee 500 Dichyopblenyxssssssisssee eee eee 575, 603 alpima. ee eae 576 WMINOM sono 5 bon cee 576 signata ....575, 576, 603, 603 NAMES. INDEX OF SYSTEMATIC 709 Page. Page. DTH DY See me aeass seme ssepe a 472 | Embassis alternans..........-... 467, 468 DINICTISM aa sere sae eee sae 509 MAPCMAISE eee se eeeee 463 felima a ssoscace seats 509 | Emys euthnetus .......-... 20... 436, 437 Dinosaubia:--eessceeee es 430, 451, 442, 444 ELA IS Sa oo sere aS GU ee Aa DmMobheniwmen sees ease cisco 463 me paul axe een ee eee 436 DIOS DWUOS| se cee eee oo eee ee 421 pachylomuGs--ep sees ees 436 AN CEPS a2 Y es -jie cia ataraa= 382 festudineds see eeeeer eee 441 brachysepala ...-..--.- 381,401 | Endropia vinosaria.... . ......---- 554 Copeanaiensijs- asa sis 389, 414 | Ennomos coloradia............---- 554 lancito linea see 381, 324, 385 | Entomostraca ..-............539, 542, 614 stenosepala-...--....-.--. SOl4|PMobasileus...<- asec. soeeiaene 456, 481, 482 OAT OU ISS Ie areca ae a Co eee rs 588 CORN SH ee ee ena assimlatar aac eters 590 furcatus eee sos es ae 457 ALPUPCS 21a ve es varoc ls there sraisys 088, 603 galeatus.-—- ae. cee nek 456 COStifeL a Ssose cate arene eee 588 DECSSICORNIS esses 457 GECISA seo Stree ema 588, 589, 603, 605 | Eobasileidw ........--..----- 462, 483, 485 pallipes) Gasa.c. usecase 589, 603, GOS yl ee phe mergieere seiner ccnbesees 578, 582, 603 SCObICAl 2 seats Seas 590 compar -=2.--- 078, 3 9, 603, 605 SOMICINCLA Zeee eee eee DOO NOUS WM Aanic are ce keene eer 580 WACIN Gees oom ase eee 588, 589, 590 decorasess-ee- 578, 579, 5E0, 603 Diplazium Muelleri......---. 376, 380, 393 OlAUCONS meeeee eae ee 579 MiploglosSasess.-1.sssesonas ee ese 512, 513 guttulata.......-.- 579, 580, i Diplotaxis obseura_....--.-------- 569 lineabars2 -2e3 2 Gee entecee Diptera —te cesses 539, 540, 541, 561 Tube gasses se ae e WOM CHOPUSL s+ 21s meee seseees 941 MY OPS) = ys -,sceser aes 580 DOMbSyOPsis=55.e-eoe eaaeot See 421 mMaataleee sine ee 580, 581, 603 Ot PERRO Goomeeosease 387 WHUIGE IP BasSosduedodaese 581 grandifolia ....- odd, coe, 404 |" Wiphemerina--2 2... -«esee 578, 603, 605 Obtusatesscasss sS5e "203, 382 | Epicallia virginalis............... 559 occidentalis ..... .... 382 | Epicauta maculata...--.-.--.-..-. 70 CEL VA Ie a(eyaee yea 382, 404 PEUINOSAee see jaOS6 570 DOMMMAw ace a sos rense AG ;408; 469) aE pithecase ssa eae eeee eae 590, 604 CLASSIGENIS)= sees es Soe 469, 470 ALCtCA ete eee ONOOL OTACTIST Neale aac ysees 470 TOTCA Aaa te ie 590, 591 Sradabaver ae sees sere 468, 469 semicireularis..-.---. 590, 604, 605 Dory phora decem-lineata.--..----. 970 | Equisetum Haydenii--....---. 386, 388, 390 ID rassoid as see ass wee onsee ee eens 542 len mexy grote S36 356 ade5c 380, 395 Dremotherium sees ease aces 502 limmosumne eee een 384 MEE PAN ODOM. - sso: ae seco as 507 Wyomingense -...---- 388, 409 Drepanodon occidentalis .---...... SOOM ele GMS wane een ol secs set renrereeee 525, 528 PLM VAIS) eee eee SOOM Wiiaxcis ae wicca oyna cies omtotneietniars 5638, 565 Dryandra Veronensis ...--..------ 3/0 || Hrebia Epipsodea.-.-....----..--- 542 IDTISCIMee sac oe) Ske ose ae oes ane ne DOSn PE MebUS|Od Olas caas eee ere eee 554 Dytiscus marginicollis -...-...---.- SOSH PETIA Cee seat essai ee eee ar 379 IGCINACEUS se se Secles leno eee 473 Eriocaulon porosum ...--.-.----- 380, 396 PIC HIMOMVAa se a= sce nee aeeaee ees 504s PE TIEMINUS! cao = to estee Serenata 570 BiezonUs inequalis.-...22-.-6->- | sol |Erismatopterus..o-----cu-t--,---- | 461 Elaphrus californicus.......--...-. HOSUih Tisballiisy aacursisesiecsee sees eases 564 IBM aibenid gor ete se ares os eicio cites coe SOO a Bina tylidss sae nee ee a eee ieee Oe Hilcodes OXtriCapar->= == elm 541 Ta DAV Bie ae aeelc eee eels aimee sue ewe DOS DI-INGktWas cee @e sweeten 563 TL INDEX OF SYSTEMATIC NAMES. Page. Page. Juarentia cesiata ..-.-.--..- 22-52. BY A Mbit ses aepiseaeos usr omeceece 607 dulwitataeee eee see cere 544 Americanus 22.2222 22. .542; 607 Lastrea Styriaca ..---.-.--..----- 418 paucidens!=cese eee eee 607 Latanites parvulus .......-..--..- 375 | Lithosia argillacea.............- 539 AU AUBUS i See hee eee ae arene aoe 421 | Lithostege rotundata .-..-........ 547 @olomblt te eee eee eee vel, 384 MISELLAUAE A= aaa euee ee 547, 549 PON PEST clea ya clyenie gence 375 | Lobophora carpimata......-....... 549 pedenbay) Sus ery Leah 377, ool, 383 halteratay ease 549 joe, Goecesssccnosss 344, 389 montanata..........-.547, 549 sessiliflora .-.-...-.-.. Sed, Galop 407 |W IbeommeMnby Sess cscecaccensce caoscess OMe Leguminosites-..\....---.---..---390) 418 Bolcensisieeeeaeeeeees 376 Le pidoptera, 539, 540, 541, 543, 546, 599, 615 Vabior ss eee seicce weleieeaee 376 Tire pico us ee ae eye serie se real eee 619 | Lophiodon ...... oy eas Se ao solaciais seisseeieescer 616, 619 | Lexolophodon cornutus - Sean ee 456, 457 JOROGINGWOS sscoceceuocccs GION MGoxonemianserereeee ee eaee ome 252 Leptauchenia calearata -.....----- 302) lnuie ami dee ee ese ee OOO, MUNN SG ooscaoudesse SO || Ines MMOMON Seeks ebog cece ooo... GAL Leptesthes erassatelliformis. ...--. 436 TUStiCa sh chee ae gen OAS Wepticthis ise sec SNe 470, 471, 472 | Lycopodium promt Ee er suatstey AX0 9) aydentijes -aeee eee. AGAN iy COSOIGCe He ees see eee eee eM tides 25 kes she cee ae cice emcees 563 | Lyda Carpenterii . Bans seattle Cee 541 IDG DUOGEINOD ME Sse scarcsoasoaccccoor 510 | Lygeeus circumcinctus ............ 541 WWeptoolossale eee ee see cece meee ee 512 TREC) 6 oo boc ce ce no ES SELL Leptomeryx...--....-.-.---.501, 502, 503 | uyygodium compactum....-..-..... 380 ; @VanSileeee-yeeeee 464, 502, 503 neuropteroides -........ 388 Mepiophlebiaieese see eaee eae eee Bie, GUS. |) ILIAC Sooo 55 Coons Soocesasmaces 613 ihelivaipesteceecaeeeee BIS |) Joy visuey iho eo S65 occ ecodesacs 570, 571 pallipes s2-23e-cene- 582, 603 Spheenicollisi eee ese seee 570 . TCWG ise Nees s cM eae areenae ATT ESTES Moko s aise i nui ease peated 598,604 | Macaria Californiata..-.-........- 553 GOORIN nosccascbsose 598, 604, 605 dispunchasesseeeee eee 549, 553 CUS MINGUE caso bdoaKs opocee 598, 604 EnoObaba cose cette eee 553 fOrCIPAtAy cases dae eee eee 598 Sex-mMaculata 2 seee ose 553 hamatae cic ces eee 598;/604; 605) | Machserodus=-<)222- 22) 2e sees 508, 509 Wilbe lal ay ses se) cores a oeneisa 583, 587, 603 - Oreodontises. 4-2. +5 <6 509 composita .... --.------- 587, GOST PMacrauchenianne. ss.) sees eee 499 croceipennis --...-.. 586, 587, 603 | Macrosila quinque-maculata....... 559 HAVA GitasemiGeeiaer sees 587, G03) RMocnoliasseersseee eter eae 376, 421 LOLETISIS sae eects 585, 603 aAltermans\ae See ee 376 MOCNISMCD woo osogcac 583, 585, 603 capelllini cases ae ae OO pulchellagase eee eee 585, 603 cordifolia... ..... 382 4-maculata .....-.......583, 603 Hilgardiana, old, 382, 383, "385, 386 SAUUIPMIAY Ssdc55\Soo6 bsocce 586, 603 Inglefieldi eg Wa a 382, 387, 388 Deion ays eee eee ny 583, 603 Janrifoliag.sco4s toe 382 Limenitis Weidemeyerii.-....-.--. 542 Lesleyana - -377, 382, 383, 403 Limnadella coriacea ..----....-.-- 618 OVALS Hee aa OU ena ae 302 GigE ts eS ene OLS | Malachidey ase s-1-)2 oe eee 569 himmadiaeeee sees ee 613, 614, 615, 618 | Mamestra picta.---.--.----..-.-.. 555d AGASSIZ eee eee eee eee 618 | Marmopteryx marmorata.......... 502 Americanass sss. .222-- 618 tessellata f22555 52255 Pp bb2 COTMACEA ea eee He ORO NV LARbeSheniaras) erneass eee EEO NS 8 1 520 DUO AS ae loves shauerae eran 615, 618 MUSCCLMUS ee eee eS 520 iEermanniy eee eee GUOE | Milastotlomeseeeisencen eee 519, 531 eRexann ate Saale sei e 618 MIUTIMCUSPSses eee ee eee 532 Hearne Oley eo eee ee ee mayer 613, 617 Ohioticus\ cosas eee 519, 532 Dah cap ofr Se SSA eee UN ee Ue Sa ye) 341, 343 PROAV UB ae oars 531 Limnephilide ..-..... 602 | McClintockia Lyallii....---....-.. 382 Mimmephilus| 2a ea.seeeee- ~ 600, 602, 604, GOGS} Meekiiay cys ss tse aeons 455 rhomibpicusjseses eee 600, 606 bullatays 225. ees Seren see 455 LALO NCO eRe Memos sHiccadmerare 618 Sella. Mo Shey ae hen se 455 Gouldit se ee ae 618 | Mewaceratops acer.-...------..--. 488 gracilicornis....—..--- 618 coloradoensis ..--..- 430 Trin pula ese eee snes mss 201, 208 heloceras.-........487, 492 Eingulepis 2.252. 22.25... --.------ 208 |) Meracerops coloradensis 324-2222. 484, 485 Liquidambar gracile......-...---387, 422 | Megalaspis .-.--..---..-..---- eH calls, integrifolium. . 422) Pe MeSalosaunusie assets ese eee 445 Miriodendroneesssee ese eee 377, 385, 422 | Melanippe concordata....-.-.... 550 istrusysenilisiens see eee 569 SOMATA eee eee 500 INDEX OF SYSTEMATIC NAMES. (ke Melanippe hastata ...............- 550 Kodiakatan. jase 28 a4 550 luchuataeeecas seers 550 lusmbrama esse teens 544, 550 thistataes- 2) seke een Dd Melanophila longipes .-.--.-....-. 569 Meliphreptus: 220 Ke esses ae 564 eylindnicustsessee ose 564 Meloe near angusticollis........... 570 Moloidaes sn o..42- saeco ese se tacece 570 Menoiherinimiys 2 ese cae acee ae 510 lemunimum)-.ceeeee 510 Menycmippusrssece -b-n 0 seee see 524, 528 Merychyus -.--..---- A seadGuac case 462, 529 elocans\.eesenoe neers 529 Maj OLS oso asset ence 529 Mer yCOdUS:: - 2. Sse was clase eee 531 FEMMITEE ee sees see 531 necatus ----..-.- Eamioeiee 531 MIGSOUNV IX apie setae Soviss ose oe mewn 461 Mesoihemismasce-\cssmaeceease eee 587, 603 collocata.2---..------ 259875603 corrupta ...--.-.. 587,.603, 605 UilOtamesncete eee eee 587, 603 longipennis.........-.. 588 simplicicollis .-........ 587 Metabletus americanus...-.......- 568 Metalophodon armatus..........-. 437 WMI), 2 cei eae oe wc teense 574 MERC ROIDUS! Seon na oe Acne noe ae 599, 605 SODEUS HS stiec\secaee one 599 Whilitzaminuibae<-sosjecesee ence a6 < 542 mnbiceriaee= see eeer eee 541, 542 Miobasileus hypoceras........--. -- 491 opbryagnasetehe cece = 490 MiORMUS sie 52 estas oct sen eee 604 SODIUM NSS See ecceeeee 604 Miothen crassigenis.....-...------ 470 Sma GWO Ms amram eisai siaesee 470 WIG OER Se a eSB eee ee oe ae eae 542 Monilema annulatum.----.......-- 570 Monohammus scutellatus ..-...--- 570 Mordella scutellaris..---.--..--..- 70 Moxdellidioy: = sacs Secciyoetnceieses 570 Morus aiimisy. = e055 cgcenatceeos- 385, 386 VEIT OG Bere oe je ae ai5)s Seianis Sone S= 475 14 [S| Se ee ae age ee er 474 decunianuds-