BERKELEY 
 
 L'\;ARY 
 
 UNIVERSITY OF 
 CALIFORNIA 
 
 EARTH 
 
 SCIENCES 
 LIBRARY 
 
DEPARTMENT OF THE INTERIOR. 
 
 !.(>!.m;U'AL AND liKOGRAPHICAL SURVEY OF THE TKRIUTORlIih! 
 < i 
 
 W. POWELL, OKI .1.1 MUST IN CJ 
 
 i^ 
 
 GEOLOGY 
 
 ' OF TI1K 
 
 EASTERN PORTION OF THE UMA MOUNTAINS 
 
 A REGION OF COUNTRY ADJACENT THERETO. 
 
 WITH 
 
 BY J. W. POWELL. ( 
 
 WASHINGTON: 
 
 GOVERNMENT PRINTING OFFICE. 
 187C. 
 

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G.VI K OF I.ODORE. 
 
Y OF 
 
 PREFACE. 
 
 The region of country embraced in the map which accompanies this 
 report is one of great geological interest. Three great categories of facts 
 are here represented on a grand scale, viz: facts relating to displacement, 
 facts relating to degradation, and facts relating to sedimentation. The dis- 
 placements arc of great magnitude, and because the beds involved are sedi- 
 mentary strata but rarely altered, the characteristics of these displacements 
 are plainly revealed, so that in our studies of them we have been able to 
 arrive at conclusions, both quantitative and qualitative, with some degree of 
 certainty. 
 
 While displacement has been great, degradation has also been great, 
 yet the country has not been planed down to a general base-level, but stands 
 in mountain cliffs and escarped hills, where the strata are plainly revealed.. 
 
 The formations which we are able to study here have an aggregate 
 thickness of 50,000 feet, and embrace groups of Paleozoic, Mesozoic, and 
 Cenozoic Ages. Throughout nearly the entire region there is a condition of 
 surface which renders the study of the geology comparatively easy. By 
 reason of great altitude and extreme aridity the rocks are rarely masked by 
 subaerial gravels, soil, or vegetation, and the book of geology lies open. 
 We have thus been able to collect a large body of facts, which, in the fol- 
 lowing volume, have been arranged in such order as it seemed would best 
 present to the reader the general geology of the country. Many details 
 have been omitted which would have been given had the facts been pre- 
 sented as they w*ere collected in the form of an itinerary, but it was though 
 that, such a method would result in encumbering geological literature with 
 
 a mass of undigested facts of little value. 
 
 Ill 
 
IV PREFACE. 
 
 It may be well to indicate here the general routes of travel by which 
 the country has been explored. In the fall of 1868 with a small party of 
 men I crossed from the White River to the Yampa, and camped at the foot 
 of Junction Mountain; thence I passed northward across the Snake River 
 to the Pine Bluffs, and thence westward across Aspen Mountain to the 
 Green River, and up the bank of that stream to Green River Station; 
 thence I crossed to Bryan, on Black's Fork, and down that stream to 
 its mouth, then went south to the. Cameo Mountains; thence eastward 
 to Quien Hornet Mountain; thence to Flaming Gorge, and from this 
 latter point to Ashley Park, and from Ashley Park to Brown's Park. From 
 Brown's Park I went through the Escalante Peaks, near the junction of the 
 Yampa with the Green ; thence eastward past Junction Mountain to the 
 White River. 
 
 The course thus laid down is the general one of the pack train, but I 
 myself branched from it in many ways. 
 
 On this journey I first discovered the succession of Cenozoic and Meso- 
 zoic groups, but did not divide the Upper from the Lower Green River, nor 
 did I draw the plane of separation between the Upper Green River and 
 Bridger Groups where I do now. 
 
 Early in the spring of 18G9 I again crossed from the White River to 
 the Yampa, camped at the foot of Junction Mountain, and spent a few 
 days in the study of the adjacent region. I proceeded thence to Brown's 
 Park, in which I camped for a few days, reviewing the geological studies of 
 the previous fall. I then passed out of the park through Red Creek Canon, 
 from its head, crossed the divide, and proceeded westward to the Green River, 
 and camped again at Flaming Gorge for a few days. Thence I went up 
 Henry's Fork, studying the region on my way, and crossed the divide to 
 Fort Bridger. 
 
 A few weeks Subsequent 1 started on. a boat trip to explore the lower 
 Green and the Colorado River of the West, On my way I passed through 
 the Uinta Mountains, stopping from time to time to make sections and to 
 make geological studies of the country along the walls of the canons. 
 
 Again, in 1871, I had a boat ride down the river. On this trip Mr. 
 .John F. Steward, of Piano, Illinois, was my assistant. We extended our 
 studies on either side of 1 lie river for a distance of from ten to twentv miles. 
 
PREFACE. % V 
 
 In 1874, I started with a pack train from Green River Station, went up 
 Little Bitter Creek, across Quien Hornet Mountain, through Red Creek 
 Canon into Brown's Park; thence southeastward to the junction of the Snake 
 River with the Yarnpa, where it was crossed; thence across the Yampa 
 Plateau to the foot of Split Mountain Canon, and thence to the Uinta Val- 
 ley. Returning from the Uinta Valley I visited the region drained by 
 Ashley's Fork and Brush Creek, crossed the Uinta Mountains to the head 
 of Sheep Creek, and returned to Green River Station. 
 
 The course thus marked down was that followed by the pack train, 
 which moved but slowly, usually resting two days out of three, while my 
 own line of travel was in diverse directions from this general route. 
 
 In 1875, I again started with a pack train from Green River Station, 
 went east to Rock Springs and Salt Wells, thence south to the mouth of the 
 Vermilion, thence to the eastern foot- of the Dry Mountains, thence west 
 through Brown's Park, past Flaming Gorge to the head of Sheep Creek, 
 and thence through the Cameo Mountains to Green River Station. On this 
 trip also the train moved slowly, and my studies were extended many miles 
 in either direction from the general route. 
 
 A few days later I made a trip to Salt "Wells and Bitter Creek Stations, 
 and particularly examined the region about Black Butte. 
 
 The last part of the descriptive geology has been greatly condensed ; 
 this is especially the case with the description of the structure of the Yampa 
 Plateau, Junction Mountain, Diamond Peak, the Dry Mountains, Brown's 
 Park, and the Aspen Mountain district. It was intended to illustrate the 
 structural characteristics of these regions with a series of diagrams and sec- 
 tions, but the plan was abandoned because the appropriation was exhausted. 
 It was intended also to prepare a chapter on the physical features of the 
 region, treating of the mountains, plateaus, monoclinal ridges, hills, parks, 
 bad-lands, and alcove lands, and further treating of the three great kinds of 
 drainage found in the region, viz, antecedent, consequent, and superimposed; 
 but the necessity for immediate publication Avas so great that this plan has 
 also been abandoned, and to this subject I hope to recur at a future time. 
 
 On my travels during the year 1875, Prof. C. A. White was my geo- 
 
VI PKEFACE. 
 
 logical companion, and the trip was made largely for the purpose of collect- 
 ing fossils at localities where they had previously been discovered, but 
 to which sufficient time had not been given to make good collections. But 
 many places of interest on account of geological structure were also visited, 
 and I had the good fortune to have with me an experienced geologist on 
 this my final review of the region ; and to Professor White, whose paper on 
 paleontology appears in this volume, I am greatly indebted. Nor must I 
 fail to mention the valuable services of Mr. Steward; as he was with me in 
 one of the earlier years of the work, and only in a portion of the region, his 
 studies were but fragmentary, and the results have not been directly incor- 
 porated in my general account of the geology of the country. I feel that I 
 have not done him full justice in this matter, but the plan of publication 
 would not permit the incorporation of his notes bodily; nor would such a 
 course have done him justice, from the fact that a more extended study lias 
 greatly modified opinions entertained by both Mr. Steward and myself at 
 that time. 
 
 For the map I am indebted primarily to the labor and skill of Prof. A. 
 II. Thompson, who has been my collaborator for many years, but in the 
 work he has had several able assistants; and in the year 1874, Prof. H. C. 
 De Motte, of the Illinois Wesleyan University, traveled with me for the 
 purpose of more thoroughly studying the details of Jhe geography more 
 distant from the river, and he somewhat extended the area of the survey 
 embraced on the map. 
 
 To Mr. Gilbert, I am indebted for great assistance in the preparation of 
 the graphic representation employed in illustrating the Report. 
 
 The diagram, Plate VII of the atlas, was prepared for me by Mr. 
 Archibald R. Marvine. In the earlier years of my travels in the Rocky 
 Mountain region, I studied to some extent the Park Mountains. Subse- 
 quently the region was more thoroughly studied by parties under the 
 direction of Dr. Hayden, and in his connection with that work Mr. Marvine 
 traveled over much of the same ground that I had seen. It thus happened 
 that we frequently discussed together the country which had been visited 
 by both of us, and when I came to the preparation of this volume Mr. 
 Marvine kindly proposed to construct this illustration for my use. This is 
 
PEEFACE. VII 
 
 perhaps the last work done by Mr. Marvine ; at the time he was in very 
 ill health, and a few days after sank into a condition from which he never 
 recovered, and we now have to mourn the loss of a conscientious, able, and 
 vigorous geologist, and it is with profound sorrow that I am compelled in 
 acknowledging his courtesy to record his death. 
 
 Mr. J. C. Pilling, for the past three years, has traveled with me as 
 stenographer an 4 assistant geologist, and to him I am indebted for the col- 
 lection of a great body of details of diverse character, but especially in the 
 measurement of many sections. 
 
 Mr. W. Cleburn, one of the engineers of the Union Pacific Railroad, 
 and who has been engaged in that work for many years, has at the same 
 time interested himself in the geology and paleontology of the region, and 
 to him I am indebted for many favors, and especially for the use of his 
 valuable collection of fossils. 
 
 To many of the citizens of the region I am indebted for courtesy and 
 substantial favors, but especially to Capt. Pardon Dodds, of the Uinta Val- 
 ley, and Mr. S. I. Field, of Green River Station. 
 
 J. W. P. 
 
 The following note from Professor White is inserted: 
 
 DEAR SIR : Since my report, comprising Chapter III of this volume, 
 was put in type, further investigation of the fossils collected from the Canon 
 of Desolation has led me to doubt the correctness of the reference I have 
 there made of them to the Point of Rocks Group. It now seems probable 
 that they properly belong to the Bitter Creek Group, notwithstanding the 
 close relationship of two or three of the species with some of those found in 
 strata that are still referred without doubt to the Point of Rocks Group. 
 
 Further collections and investigations in the field will, however, be 
 necessary before this question can be definitely settled. 
 Very truly yours, 
 
 G. A. WHITE. 
 
 Prof. J. W. POWELL. 
 
CONTENTS. 
 
 CHAPTER I. 
 
 THREE GEOLOGICAL PROVINCES. 
 
 Page. 
 
 Geographic characteristics of the three provinces ............................................... 7 
 
 General characteristics of the sedimentary groups ................... , .......................... 8 
 
 Characteristics of orogr aphic structure ....................................................... 9 
 
 Types of orographic structure ............................................................. 9 
 
 Orographic structure of the Basin Province ..... ......................................... 23 
 
 Orographic structure of the Plateau Province .............................................. 25 
 
 Orographic structure of the Park Province ................................................ 26 
 
 History of the three provinces during Ceuozoic time ........................................ 32 
 
 CHAPTER II. 
 
 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 Table of the groups of sedimentary strata ...................................................... 40 
 
 Localities where the several groups can be studied ......................................... 45 
 
 Section of White Cliff, Vermilion Cliff, and Shinarump groups ........................... ... 53 
 
 Uinta Mountain section ................................................................... 57 
 
 Cataract Gallon section ................................................................... 58 
 
 Grand Cafion section ..................................................................... 60 
 
 Epochs separating the groups ............................................................. 62 
 
 Liguitic coal .............. ......................... . ..................................... 73 
 
 CHAPTER III. 
 
 INVERTEBRATE PALEONTOLOGY OF THE PLATEAU PROVINCE. 
 
 Letter of transmittal .................. "By C. A. White, M. D." ................... J ........... ?4 
 
 General observations ......................................................................... 75 
 
 Lower Silurian Age ....................................................................... 79 
 
 Upper Silurian and Devonian Ages ........................................................ 79 
 
 Carboniferous Age ........................................................................ 79 
 
 Mesozoic Age ............................................................................. 80 
 
 Cenozoic Age ................................................................... . ......... 84 
 
 Catalogue of fossils ............... . ............ . ..... . ......... . ............ .. _____ . ____ ...... 88 
 
 Carboniferous Age ........................................................................ 88 
 
 I 
 
2 CONTENTS. 
 
 Tage. 
 Catalogue of fossils Continued. . 
 
 Mesozoic Age 92 
 
 Jurassic Period 92 
 
 Cretaceous Period 94 
 
 Cenozoic Age 102 
 
 Tertiary Period 102 
 
 Descriptions of new species 107 
 
 Carboniferous 107 
 
 Jurassic 110 
 
 Cretaceous 112 
 
 Tertiary 125 
 
 CHAPTER IV. 
 
 GEOGRAPHIC DISTRIBUTION OF THE GEOLOGICAL FORMATIONS IN THE UINTA MOUNTAINS. 
 
 Red Creek Quartzite 137 
 
 Uinta Group 141 
 
 The Carboniferous groups 146 
 
 The Jura Trias groups 150 
 
 The Cretaceous groups 153 
 
 The Cenozoic groups 161 
 
 CHAPTER V. 
 
 STRUCTURAL GEOLOGY. 
 
 The eastern portion of the Uinta Mountains 176\ 
 
 Displacement 176 
 
 Degradation 181 
 
 Disintegration 182 
 
 Transportation 184 
 
 Scholium relating to the epoch of upheaval of the Basin Ranges 198 
 
 Sedimentation 198 
 
 The Yampa Plateau 202 
 
 Scholium relating to the terms " upheaval," " subsidence," &c 203 
 
 Junction Mountain 204 
 
 Diamond Peak 204 
 
 The Dry Mountains 206 
 
 Brown's Park 208 
 
 Aspen Mountain district 209 
 
CHAPTER I. 
 
 THREE GEOLOGICAL PROVINCES. 
 
 The Colorado Elver of the West drains a vast system of plateaus. On 
 'these plateaus are lone mountains, short ranges and groups of volcanic cones, 
 and the principal affluents of the river have their sources in high mountains 
 that stand on the rim of the great drainage basin. There is no considerable 
 valley along the course of the Colorado River north of the thirty-fifth par- 
 allel nor along the course of any of its principal tributaries. The streams 
 run chiefly in deep canons which, with other important topographic features, 
 serve to divide the area into plateaus. The district of country of which I 
 thus speak is, in its important characteristics, a plateau region. 
 
 This plateau character was well recognized by Dr. Newberry. In his 
 report to Lieutenant Ives, page 41, he says: "The Colorado rises in a thou- 
 sand sources at an elevation of from ten to twelve thousand feet above the 
 sea, on the western side of the Rocky Mountains. Descending from their 
 fountain heads, its tributaries fall upon a high plateau of sedimentary rocks 
 which forms the western base of these mountains and occupies all the inter- 
 val between them and the great bend of the Colorado River where the river 
 enters the volcanic district already described;" and elsewhere in that vol- 
 ume he makes frequent mention of these characteristics. 
 
 Mr. Blake, in the third volume of the Pacific Railroad Surveys, Part 4, 
 page 42, also mentions this topographic character as follows : 
 
 "Extent of the table lands ivest of the Sierra Madre. This is a convenient 
 point from which to take a general view of the broad expanse of the great 
 plain that lies between the Sierra Madre and the mountains which form the 
 
4 THREE GEOLOGICAL PROVINCES. 
 
 eastern rim of the Great Basin. From the Sierra Madre up to this place 
 the survey followed the eroded valleys of the streams, and the vision WMS 
 bounded on both sides by their high and rocky banks, composed not only 
 of the edges of thick horizontal strata, but often capped with the harder and 
 more unyielding solid lava. The observer as he passes westward from the 
 mountains is thus placed below the general level of the plateau, which does 
 not become apparent to him unless he stands upon the top of the mesas find 
 can thus cast the eye over the whole. The point already reached in the 
 description is about half way between the Sierra Madre and the high mount- 
 ains of San Francisco, and here, as we have seen, the upper strata of the 
 plain are denuded and washed away, so that the banks of the streams are 
 not so high, and the country appears more level or gently rolling. From 
 this place the vision is unbounded toward the north, except by the horizon. 
 The plain stretches far away, without any vestige of a mountain range. 
 Indeed, it is the continuation of this plateau which rises upon the flanks of 
 the Park and Wasatch Mountains at the far north, and through which the 
 waters of Grand and Green Rivers cut their deep canoned channels. Farther 
 south, these streams unite to form the great Colorado, which is also found 
 traversing this grand, plateau." 
 
 Our studies of this great plateau region have not progressed so far that 
 we are able to clearly define its boundaries, but these studies have shown 
 that the region is complex topographically as well as geologically and is in 
 fact composed of many tables; 
 
 In this region the succession of sedimentary strata is unlike any series 
 which has been studied elsewhere in North America ; different groups and 
 different groupings of fossils are found; a different series of unconformities 
 is observed and the displacements by faulting and folding have characteris- 
 tics not commonly observed elsewhere. All these facts seem to warrant the 
 conclusion that this plateau region should be considered as a distinct geologi- 
 cal province, and in this brief report and others which are to follow I shall 
 so consider it. 
 
 A notice of its geographic connection with the surrounding country is 
 needed. That portion of the United States west of the one hundredth merid- 
 ian lies at a great altitude above the sea. The exceptions to this, as immedi- 
 
THE ROCKY MOUNTAIN REGION. 5 
 
 ately along the Pacific coast and the narrow vallevs of some of the princi- 
 pal streams, are but trivial. The rivers descend so rapidly from the upper 
 regions that few of them are of value as highways of commerce; the valleys 
 proper are narrow: treeless plains, cold, arid table lands, and desolate 
 mountains are the principal topographic features. The more conspicuous 
 of these are the mountains; lone mountains, single ranges and great groups 
 of ranges or systems of mountains prevail. Owing to great and widely 
 spread aridity, the mountains are scantily clothed with vegetation, and the 
 indurated lithologic formations are rarely masked with soils, and the rocks, 
 as they are popularly called, are everywhere exposed; hence all these mount- 
 ains are popularly known as the Rocky Mountains. But there is more 
 than one system of mountains, and later writers wishing to be more definite 
 speak of the Cascade Mountains, the Coast ranges, the Sierra Nevada, the 
 Wasatdi Mountains, &c. But in an important sense the region is a unit; 
 it is the generally elevated region of the United States; it is the principal 
 region of the precious metals ; it is the region without important navigable 
 streams: it is the arid land of our country where irrigation is necessary to 
 successful agriculture. But above all it is the rocky region; rocks are 
 strewn along the valleys, over the plains and plateaus ; the canon walls 
 are of naked rock; long escarpments or cliffs of rock stand athwart the 
 country, and everywhere are mountains of rock. It is the Rocky Mountain 
 region. There is a necessity for popular purposes for some general name 
 and this one so appropriate will doubtless continue to be used, and it would 
 seem best not to attempt to confine its application to any more restricted 
 area ; but as our geographic and geological knowledge increases so that we 
 are able to reasonably and appropriately define distinct ranges and systems 
 of mountains within this great group, other distinctive names should be given 
 t< such ranges and grouj 
 
 Influenced by this consideration, in speaking of the mountains that stand 
 about the Plateau Province I shall use names for certain systems which 
 seem appropriate to characterize them as distinct from other systems within 
 the #reat Rocky Mountain region. 
 
 The eastern affluents of the Colorado River have their sources in the 
 lofty mountains that stand as walls abut the crreat parks of Southern \Vyi- 
 
6 THREE GEOLOGICAL PROVINCES. 
 
 ming, Colorado, and Northern New Mexico, and these mountains constitute 
 a system as well denned as we may hope for geographic systems to be de- 
 fined by nature; and since my studies in that region in 1867 '68, I have 
 been accustomed to speak of them as the Park Mountains. The system is 
 composed of many ranges, some w r ell defined, others complex^inclosing, or 
 nearly so, the North, Middle, South, and San Luis Parks, with many minor 
 valleys and parks; and there are short outlying spurs and ranges with other 
 parks and valleys. The principal mountain ranges are composed of nieta- 
 morphic rocks with unaltered sedimentary beds on their flanks. Some of 
 the more western mountains are chiefly of this latter material, and many 
 of the subsidiary mountains are of eruptive origin. Altogether they con- 
 stitute a geological province characterized by a great development of meta- 
 morphic crystalline schists with patches and structural basins of marine and 
 lacustrine sediments, and a complicated series of vulcanic formations. 
 
 Southward from the Oregon line, through Western Utah, Nevada, 
 Southeastern California, and perhaps across the Colorado River in Western 
 Arizona, many short and more or less distinct north and south ranges are 
 found. The valleys and plains separating these ranges are covered with 
 rather late subaerial gravels masking the underlying formations. The 
 ranges are composed of metamorphic crystalline schists with Paleozoic beds 
 on their flanks, or sometimes, even in large part of Paleozoic materials both 
 complicated to a greater or less extent with eruptive beds; these eruptive 
 beds themselves sometimes forming the principal component parts of the 
 ranges. 
 
 The little streams that have their simrces in these mountains empty 
 into salt lakes, or elsewhere their waters are lost in the sands; as it is popu- 
 larly said they disappear in sinks. The most important of these is the 
 Great Salt Lake, but there are many other basins without drainage to the 
 sea. A few of the ranges are drained into the Colorado River. To this 
 group Mr. G. K. Gilbert has given the name Basin Range System, which 
 seems appropriate. 
 
 It will be found convenient also to treat the area occupied by this group 
 as a distinct geological province. It has a series of sedimentary beds differ- 
 ing widely from the Plateau Province; they are older, and the sediments of 
 
GEOGEAPHIC CHARACTERISTICS OF THE THREE PROVINCES. 7 
 
 the latter were in large part derived from the former. The Basin Province 
 was the dry land that fed the sea and great lakes of the Plateau Province 
 through a long period, while many groups, each thousands of feet in thick- 
 ness, were deposited. 
 
 Thus, for convenience of geological discussion, I speak of three great 
 geological provinces the Park Province, the Plateau Province, and the 
 Basin Province in order from east to west. 
 
 The area included in these three provinces lies east of the Sierra Ne- 
 vada and west of the Great Plains. In a general way the northern boundary 
 is marked by the North Platte, with its proper upper continuation the Sweet- 
 water River whose minute upper ramifications interlock with those of the 
 Shoshoni River, which latter is a continuation of the northern boundary 
 until it is crossed by the forty-third parallel of north latitude. When the 
 region along the middle course of the Shoshoni River is more thoroughly 
 studied, the Basin Range System may be carried much farther north than 
 we are warranted in doing with our present knowledge; but I am inclined 
 to the opinion, from the fragments of geological description which we have 
 from that country, that another distinctly marked group will eventually be 
 recognized here, having for one of its characteristics a great development 
 of eruptive rocks. The southern boundary of the three provinces I am not 
 able to clearly define. 
 
 It may be well to state somewhat more categorically the characteristics, 
 geographic and geological, on which I propose to divide this great area into 
 three provinces. 
 
 GEOGRAPHIC CHARACTERISTICS OF THE THREE PROVINCES. 
 
 The Basin Ranges are short, more or less distinct north and south 
 ridges separated by desert valleys which reveal broad stretches of sub- 
 aerial gravels concealing the underlying formations. The general drainage 
 is to interior salt lakes and sinks, but in the northeast corner there is a 
 limited district drained by some small tributaries of the Shoshoni, and in 
 the southeast there is a small district drained by the Rio Virgen into the 
 Colorado River of the West. 
 
8 THUEE GEOLOGICAL PROVINCES. 
 
 The Plateau Province is composed of many tables bounded by canon 
 and cliff escarpments. On these tables stand lone mountains, irregular 
 groups of mountains, and short ranges. It is drained by the Colorado 
 River of the West and its tributaries. 
 
 The Park Province is characterized by broad, massive ranges, sometimes 
 distinct, sometimes coalescing so as to include the great parks. The lofty peaks 
 that serrate these ranges stand over snow banks that are perennial reservoirs 
 for a multitude of streams whose waters on one hanc). are gathered into the 
 Colorado River of the West, and finally discharged into the Gulf of Cali- 
 fornia ; and on the other hand they are gathered into the Mississippi and 
 the Rio Grande del Norte to be discharged into the Gulf of Mexico. 
 
 Thus, in the three provinces, we have, first, desert valleys between 
 naked ridges ; second, high plateaus severed by profound gorges ; and, 
 third, massive, high mountains with shining snow fields. 
 
 GENERAL CHARACTERISTICS OF THE SEDIMENTARY GROUPS 
 
 OF THREE PROVINCES. 
 
 The Basin ranges are composed of Paleozoic rocks with Eozoic schists 
 below, and in the Humboldt Mountain district some Mesozoic and Cenozoic 
 rocks are found. In the Plateau Province, Cenozoic and Mesozoic rocks 
 prevail, though some of the important plateaus are of Carboniferous beds ; 
 and in a few places deep corrasion has revealed still older Paleozoic and 
 even Eozoic formations. The Park Mountains are chiefly Eozoic Since 
 that age the region has been intermittently under the dominion of the 
 waters, and Paleozoic, Mesozoic, and Cenozoic rocks are found at horizons 
 interrupted ]>y gaps in the general series that are represented by dry land 
 periods, wl. : le the last orographic agencies have left but fragments of these 
 antecedent formations. 
 
TYPES OF OROGRAPHIC STRUCTUKE. 9 
 
 CHARACTERISTICS OF THE OROGRAPHIC STRUCTURE OF THE 
 
 THREE PROVINCES. 
 
 TYPES OF GEOGRAPHIC STRUCTURE. 
 
 It seems convenient to give a general account of the types of oro- 
 graphic structure in the region under consideration before characterizing 
 each province by its special type. 
 
 In this discussion I wish to use certain terms with a restricted or rela- 
 tive meaning ; i. e., in treating of anticlinal and synclinal flexures I shall 
 speak of those portions of the sedimentary beds which are adjacent to the 
 anticlinal axes as having been upheaved, and those portions near their 
 synclinal axes as having subsided. Again, "in blocks which are bounded by 
 faults and tilted, I shall speak of such portions as are at a higher level as 
 having been uplifted, and portions occupying a lower level as thrown. In 
 such cases I do not wish to commit myself to any theory of upheaval or 
 collapse in the change of the relation of the several parts of these beds to 
 the center of the earth. 
 
 In treating of the structure of the mountains under consideration it is 
 necessary to distinguish two great classes, viz, those composed of sedimen- 
 tary strata, 'altered or unaltered, and those composed of extravasated 
 material. 
 
 MOUNTAINS COMPOSED OF SEDIMENTARY STRATA. 
 
 I. APPALACHIAN STRUCTURE. 
 
 The structure of the Appalachian Mountains, with closely appressed 
 folds and axial planes tipped back from the sea, the modifications of these 
 folds by faults, and the primary and concomjtant forms of tile mountains, 
 have been clearly explained by the Messrs. Rogers and later writers, and 
 have formed the basis of many discussions concerning geological dynamics. 
 This Appalachian structure needs no further mention here, as it is a type of 
 structure which so far has not been found in the region described above, and 
 should it be found hereafter it will simply be an exceptional type to those 
 known to prevail. 
 
10 
 
 THREE GEOLOGICAL PROVINCES. 
 
 II. SIMPLE ANTICLINAL STRUCTURE. 
 
 Mountains or short ranges carved from simple anticlinals are sometimes 
 found, though this type of structure is not a prevailing one. Usually in 
 such a case the great mountain mass lies in the central zone of the uplift. 
 The fold is, of course, always found truncated by erosion, and the moun- 
 tains represent but the difference between the amount of upheaval and the 
 amount of such erosion. When not complicated by other types of structure 
 the strata dip on all sides from the center of upheaval, gently or more 
 abruptly, but the sides of the folds are never closely appressed. Such 
 mountains in primary form are gently rounded in general outline, modified 
 by the erosion of the streams running down their sides. Sometimes such 
 
 FIG. 1. Section through Junction Mountain, north and south. 
 
 FIG. 2. Section through Junction Mountain, east and west. 
 
 B. P., Brown's Park ; 8. C., Sulphur Creek ; J. T., Jura Trias; U. A., Upper Aubrey ; L. A., Lower 
 
 Aubrey ; R. W., Red Wall ; U., Uinta. 
 
 
 
 mountains are severed by rivers running longitudinally, transversely or 
 obliquely through them ; the rivers themselves having their sources in 
 regions far away and passing through the mountains in their courses to the 
 sea. In Northeastern Colorado a short distance above the junction of the 
 Snake River with the Yampa, stands Junction Mountain, which serves as a 
 
UINTA STRUCTURE. 11 
 
 fine illustration of this type of structure. The mountain is divided into two 
 unequal parts by a canon, through which the Yampa River runs. The 
 axis of the mountain has a north and south direction. 
 
 Figure 1 is a section through this mountain, in a north and south direc- 
 tion, along the axis of upheaval. Figure 2 is a section through it in a 
 
 transverse direction. 
 
 i 
 
 CONCOMITANT FORMS. 
 
 1. Monoclinal Ridfjes on the Flanks. Under conditions which are so well 
 known as to need no further explanation here, monoclinal ridges or hog- 
 backs are formed on the flanks of such upheavals, and sometimes such 
 monoclinal ridges are of such magnitude as to be dignified with the name of 
 mountains. Where two or more series of indurated, inclined beds are sep- 
 arated by extensive series of softer material, two or more monoclinal ridges 
 may be formed. 
 
 2. Monoclinal Ridges only. Sometimes we find that an anticlinal up- 
 heaval has been eroded in intaglio, so that there is no great central moun- 
 tain mass, but the axis of upheaval is the site of a valley or low plain, but 
 the monoclinal ridges on the flanks remain. 
 
 3. Inclined Plateaus. Where the anticlinal upheaval has a great ampli- 
 tude, as compared with the vertical uplift, the beds incline but slightly. 
 Under such conditions inclined plateaus or mesas are found instead of 
 monoclinal ridges, usually having steep escarpments facing the axis of the 
 flexure. 
 
 III. UINTA STRUCTURE. 
 
 In the Uinta Mountains we have a great range carved from an anticlinal 
 upheaval, the axis of which has an easterly and westerly trend, and is more 
 than one hundred and fifty miles in length. It terminates abruptly against 
 the Wasatch Mountains on the west and is cut off by the short, abrupt anti- 
 clinal of Junction Mountain on the east, the latter having its axis in a north 
 and sQuth direction. There are several important facts observed in the 
 study of this great flexure. Its axis has been lifted above the level of the 
 sea about thirty thousand feet, and above the level of the adjacent country 
 
12 THREE GEOLOGICAL PROVINCES. 
 
 about twenty-five thousand feet. From flank to flank the flexure is about 
 fifty miles, but varies much in width. We find on either flank, many miles 
 from the axis, a line of maximum flexure, which line presents a subparallel- 
 ism with the meandering axis. These lines have the effect of two mono- 
 clinal flexures in opposite directions, separated by the broad table, diversified 
 "by elevated valleys and peaks of which the great mass of the Uinta Moun- 
 tains is composed. But the portion between these monoclinal flexures or 
 lines of greatest flexure is itself gently flexed. In many places that which 
 I have called the line of greatest flexure is indeed a fault, in one place 
 on the north side of the Uinta Mountains having a throw of twenty thousand 
 feet. On the south side the line of greatest flexure is very irregular, being- 
 complicated in some places by faults having uplifts opposed to the down- 
 throw of the flexure. On either side the great displacement is partly by 
 faulting, partly by flexing, and either flank is a zone of diverse displace- 
 ment where the strata are faulted, flexed, twisted and contorted in many 
 ways. 
 
 The character of these displacements in the Uinta Mountains is illus- 
 trated in Plates 1, 2, and 3 of the Atlas, and in a subsequent chapter the 
 subject will be more fully discussed. 
 
 The simplest topographic forms produced by such displacements under 
 conditions of erosion in general outline, are plateaus with gently rounded 
 summits and abrupt shoulders on the flanks; but such general outline is 
 often modified by the corrasion due to antecedent or superimposed drain- 
 age; that is, by the corrasion of streams that head in remote regions and 
 pass through these uplifts either longitudinally, transversely or obliquely, 
 as in the case of Simple Anticlinals.* 
 
 There are other modifications which sometimes greatly obscure the 
 general topographic outline due to consequent drainage, i. e., the local 
 drainage which is due to the upheaval itself and which produces inter- 
 esting 
 
 CONCOMITANT FOEMS. 
 
 1. Subsidiary Plateaus. Sometimes the streams which head near the 
 axis of such an upheaval, as they meander to the flanks, excavate valleys 
 
 * For an explanation of what is meant by antecedent and superimposed drainage, the reader is 
 referred to the Report on the Exploration of the Colorado River and its Tributaries, page 160, ct scq. 
 
UINTA STRUCTURE CONCOMITANT FORMS. 13 
 
 and divide the great block, which is a plateau in general outline, into 
 minor plateaus which are separated by intervening but elevated valleys. 
 This is especially the case where- the streams in their upper courses 
 follow for some distance the strike of the beds before turning to cross 
 the more or less abrupt lines of maximum flexure. Sometimes these 
 streams run in deep gorges; in such cases the plateaus are bounded by 
 canons. 
 
 2. Projecting Ridges. When these consequent streams starting near 
 the axis of upheaval take a somewhat direct course across the strike, 
 the general plateau is cut into a series of sharp, abrupt ridges having a 
 trend at light angles to the strike or general axis of upheaval. Thus the 
 points of the ridges face the plain below and are separated by deep gulches 
 and canons, and the observer on the plain below sees before him what 
 appears to be a line of peaks separated by intervening gulches and valleys, 
 and is apt to misunderstand the topographic character of the great mass 
 which is before him. 
 
 3. Axial Peaks. At some stages in the progress of erosion the channels 
 of consequent drainage inosculate, and about their heads gorges are formed, 
 with towering amphitheaters. In such cases an irregular line of crags 
 and peaks will be found along the axis of upheaval. These I call axial 
 peaks. 
 
 4. Flanking Peaks. Sometimes we find a very hard bed or group of 
 beds underlaid by more friable strata on a flank of the upheaval, which 
 harder beds have been carried away by erosion from those portions of the 
 upheaved mass nearer the axis. In such cases each projecting ridge is 
 crowned with a true peak. I call these flanking peaks. 
 
 5. Interrupted Monoclinal Piidges. On the flanks of these upheavals, 
 but farther from the axis than the flanking peaks, monoclinal ridges are 
 often found sometimes broken by gaps which are the channels of inter- 
 mittent or permanent streams, and these ridges are very irregular and 
 often interrupted. Where the downthrow is by simple flexure, a complete 
 series is formed. Where it is partly by flexing and partly by faulting, 
 some of the monoclinal ridges disappear. Where the faulting is on the 
 side of the zone of maximum flexure nearest to the axis, the ridges of the 
 
14 THREE GEOLOGICAL PROVINCES. 
 
 upper beds appear ; but where the faulting is on the side of the zone of 
 maximum flexure farthest from the axis, the ridges of the lower beds appear; 
 and where the displacement is chiefly or entirely by faulting, there are no 
 
 monoclinal ridges. 
 
 IV. KAIBAB STRUCTURE. 
 
 In the region under discussion we often find the sedimentary beds 
 broken into great blocks by faults or their homologues, monoclinal flexures, 
 and these blocks have been gently tilted in broad masses. I have dis- 
 cussed this subject somewhat at length in my Report on the Exploration of 
 the Colorado River of the West and its Tributaries, published in 1875 ; and 
 in Figure 3 I reproduce a section and bird's eye view of the plateaus north 
 of the Grand Canon, which was used in that volume. An examination of 
 this will fully reveal the characteristics of what I have called the Kaibab 
 structure. The grand topographic features which result from this structure 
 are plateaus with broken edges where they are bounded by faults, flexed 
 edges where they are bounded by monoclinal flexures, and with escarp- 
 ments where they are bounded by canons or lines of cliffs. 
 
 CONCOMITANT FORMS. 
 
 1. Cliffs of Displacement. When a plateau is bounded on one side by 
 a fault, the edge of the plateau is an escarpment often so abrupt as to 
 present a more or less irregular line of cliffs. 
 
 2. Slopes of Displacement. When the displacement is a flexure rather 
 than a fold, the edge of the plateau is a broken slope. I have discussed 
 these cliffs and slopes of displacement somewhat at length in the volume 
 already quoted several times, page 182 et seq. 
 
 3. Monoclinal Ridges on the Flanks. On the flanks of these monoclinal 
 flexures, under proper conditions which have already been described, 
 monoclinal ridges are formed. 
 
 4. Monoclinal Ridges with Plateau Carried Aivay. As in simple anticlinal 
 upheavals the central mass may be entirely carried away leaving but 
 monoclinal ridges, in like manner in the Kaibab structure the principal 
 plateau mass may be carried away leaving only the monoclinal ridges. 
 This I have also discussed in the volume already quoted. 
 
Paria Platean 
 
 Virgin Valley 
 
 Pine Valley Mountain 
 
 "( > ' V ,/ V 
 
 I ,;' 
 
 Paria Fold. 
 Echo Cliffs. 
 
 Marble Cation. 
 
 East Kaibal) Fold. 
 
 Kaibab Plateau. 
 West Kaibab Fold. 
 
 Kanab Plateau. 
 Kauab Cafion. 
 
 Eauab Plateau. 
 
 To-ro'-weap Fault. 
 U-in-ka-ret Mountains. 
 
 Hurricane Fault. 
 Shi'-wits Plateau. 
 
 Grand Wash Fault. 
 Grand Wash. 
 
 I 
 
 a 
 
 a a> 
 TS 
 
 SH 
 
KAIBAB STRUCTURE CONCOMITANT FORMS. 15 
 
 5. Projecting Jtidf/cs. It is seldom, perhaps never the case that the 
 strata of one of these plateaus are left by the general displacement in a hori- 
 zontal position ; but every block is tilted more or less, and often a valley 
 appears at the foot of the slope, and the streams which head on the opposite 
 brink of the plateau have excavated valleys, leaving intervening ridges 
 which project into the valley, having an effect somewhat like that described 
 as one of the concomitant forms of the Uinta structure. On 2 
 
 6. Cliffs of Erosion. An inclined plateau may be bounded on the 
 upheaved side by an escarpment of erosion, and such an escarpment is 
 gradually carried back by an undermining process from the line of greatest 
 upheaval. The drainage of such a plateau is usually from the brink of 
 this escarpment toward the valley on the opposite side ; yet a minor 
 drainage is found which carves out deep gulches, and the cliffs of erosion 
 have deep reentrant and sharp salient angles. 
 
 7. Buttes. Sometimes the gulches which form the deep, reentrant 
 angles of a line of cliffs have lateral gulches, which by continued erosion 
 coalesce, and the salient angles are gradually cut off from the escarpment, 
 which is ever retreating. In this manner buttes are formed as outliers of 
 cliffs. 
 
 8. Cameo Mountains. Wherever considerable areas of horizontal or 
 nearly horizontal strata are found sufficiently elevated above the base level 
 of erosion, and such areas are drained by two or more subparallel water 
 courses, the lateral drainage of these water courses will gradually inosculate 
 in their upper ramifications, and, carving out deep channels, will leave 
 behind mountains of horizontal strata. Such mountains are often of great 
 beauty. This is especially the case where the beds are of different texture 
 and color, when the mountains will be terraced and buttressed in beautiful 
 regularity, and banded with the colors which are characteristic of the several 
 beds of which they are composed. 
 
 A few miles north of the Uinta Mountains, on the west side of the 
 Green River, a group of such mountains are found, to which I have given 
 the name Cameo Mountains, and I call this the Cameo structure. 
 
16 THREE GEOLOGICAL PROVINCES. 
 
 V. BASIN RANGE STRUCTURE. 
 
 When the blocks into which a district of country Jias been broken by 
 faults are greatly tilted so that the strata dip at high angles, the uplifted 
 edges of such blocks often form long mountain ridges. Such ridges have 
 the general appearance of the monoclinal ridges already described as con- 
 comitants of other types of structure ; but in this case the ridges constitute 
 the chief mountain masses themselves, and form another general structural 
 type. The monoclinal ridges are due to the erosion of upheaved strata ; 
 these ridges are due to displacement ; they may also be eroded, but in so 
 far as erosion has progressed the ridge like structure is obscured. Many of 
 the rido-e like mountains of the Basin Province have this structure. Such a 
 
 O 
 
 ridge is composed of monoclinal strata, the one side presenting a bold escarped 
 front, the other a more gently sloped back conforming to a greater or less 
 degree with the dip. Sometimes the ridges themselves are faulted longitud- 
 inally, transversely or obliquely, and the faults may be slight or of great 
 magnitude ; but the more common structure is a simple ridge with slight 
 transverse or oblique faults. 
 
 CONCOMITANT FOEMS. 
 
 1. Monoclinal Ridges on the Sack. On the backs of these Basin ranges 
 monoclinal ridges have been observed. 
 
 VI. ZONES OF DIVERSE DISPLACEMENT. 
 
 In this region many zones or irregular areas of country are found to 
 be divided into small blocks by faults and flexures running in diverse direc- 
 tions, and these may be horizontal or be tipped at high or low angles, or 
 even be overturned. The total effect of this diverse displacement may be 
 to uplift the area above or depress it below the adjacent country or not to 
 change its relative altitude. These features are exhibited on a small scale 
 within a limited area, usually so elongated as to be termed a zone. 
 
 During the past season Mr. Gr. K. Gilbert has studied an area where this 
 diverse displacement is by faulting, and the faults are of no great magnitude, 
 and the blocks into which the area has been severed are either not tilted or 
 but slightly so. This presents the simplest illustration of this type that has 
 
FIG. 4. Bird's-eye view of a portion of the Musinia Zone of Diverse Diaplaeeinent. The area represented is six 
 miles square. The base line shows the sea-level. The tract is drained by Saliiia Creek, which unites its branches 
 in the center and flows through the canon on the left. 
 
 JT 
 
 FIG. 5. Deduced from Fig. 4. A restoration of the displaced rocks as they would appear had there been displace- 
 ment but no degradation. 
 
ZONES OF DIVERSE DISPLACEMENT. 
 
 17 
 
 yet been discovered. It is simply the Kaibab structure on a very small 
 scale. Fig. 4 is a bird's eye view of the blocks mentioned. In the section, 
 in the foreground, the heavy line represents the summit of the highest Cre- 
 taceous group. Fig. 5 is a diagram of the same region showing the blocks 
 into which it is severed, and the same restored to the condition they would 
 have, had there been no denudation. 
 
 On the south side of the Uinta Mountains, and east of the Green River, 
 another comparatively simple area has been studied by myself. This zone 
 of diverse displacement is on the flank of the great Uinta upheaval. These 
 displacements are chiefly by flexures rather than by faults, and the blocks 
 arc more tilted and 'contorted than in the last. 
 
 In Atlas, Plate No. 4, we have a stereogram representing these displace- 
 ments, and in a subsequent chapter the subject will be more fully discussed. 
 
 A. Simple Anticlinal displacement. 
 
 B. Uinta displacement. 
 
 C. -Kaibab displacement. 
 
 D. Basin Range displacement. 
 
 E. Zone of Diverse displacement. 
 * FIG. U. Types of Displacement. 
 
 Many other areas for more complex than these have been discovered 
 where a zone has been broken into blocks, and these blocks tipped and 
 contorted in diverse ways and directions like the blocks of ice crowded in 
 an oddy of a northern river at the time of its spring flood. The topographic 
 features found in such areas are zones of irregular hills. Fio-ure 6 is a 
 
 r> 00 
 
 2 P G 
 
18 THREE GEOLOGICAL PROVINCES. 
 
 diagram illustrating the general types of displacement heretofore discussed. 
 A represents a Simple Anticlinal displacement ; 13 a Uinta displacement ; 
 C a Kaibab displacement ; D a Basin Range displacement ; and E a Zone 
 of Diverse displacement, 
 
 MOUNTAINS COMPOSED IN WHOLE OR IN PART OF EXTRA- 
 
 VASATED MATERIAL. 
 
 We are not able in the present state of our knowledge to draw legiti- 
 mate conclusions concerning the relation of the eruptive rocks so widely 
 distributed through all three of these geological provinces, but the following 
 types of structure have been observed. 
 
 VII. TABLE MOUNTAIN STRUCTURE. 
 
 We often find beds of sedimentary strata preserved from erosion by a 
 capping of lava. Such are usually called table mountains; the underlying 
 strata may be horizontal or inclined. Earlier stages of this structure are 
 seen in mesas or low tables, and sometimes in valleys or gulches which 
 have been filled with extravasated material, and erosion has proceeded to a 
 limited extent on either side of these harder masses carrying away the 
 softer sedimentary material and leaving the harder volcanic rocks in the 
 midst of the valley, and this may have an elevation lesser or greater than 
 that of the adjacent country beyond the rim of the valley. 
 
 A fine example of a table mountain is found in Pilot Butte, in Wyo- 
 ming Territory. 
 
 VIII. UINKARET STRUCTURE. 
 
 Simple sheets of lava may be poured into a valley or on a plain, and 
 serve as a protection to the sedimentary beds which are immediately under- 
 lying them and, as the erosion of the adjacent country not thus protected 
 progresses, new vents may be formed along the edges of such sheets and 
 at a lower level. Still erosion progresses, and still new floods of lava are 
 poured out, and still at lower levels, until a mountain is left behind with its 
 central mass composed of sedimentary material, but covered on the summit 
 
TU-SEIAR STRUCTURE VOLCANIC STRUCTURE. 19 
 
 and flanks with irregular and overlapping patches of lava. Thus lava bed 
 is imbricated on lava bed, but unlike the tiles of a roof, the upper edge of 
 the lower sheet is placed on the lower edge of the upper. This struc- 
 ture is well represented in the Uinkaret Mountains in Northern Arizona, and 
 has been more fully discus/sed by me elsewhere, vide The Exploration of 
 the Colorado River, &c., page 1 99 et seq. 
 
 IX. TU-SHAR STRUCTURE. 
 
 When a plain or valley which receives extravisated material from below 
 remains at a base level of erosion during the period of successive eruptions, 
 flood of lava is piled on flood of lava until a vast mass of material is accu- 
 mulated from which the rains and streams carve mountains. The several 
 beds of which such a mountain mass is composed are exceedingly irregular, 
 from three causes: first, each bed as poured out was an irregular mass, 
 due to its degree of fluidity arid the character of the ground on which it 
 was poured; second, each bed was more or less modified by erosion, which 
 occurred after it was poured out, and before it was covered by a subsequent 
 flood; and, third, the general mass has been eroded to a greater or less ex- 
 tent in producing the present forms. 
 
 The volcanic activity being in a region where movements of displace- 
 ment are in progress, it is often the case that the structure of this class- of 
 mountains is greatly modified by such displacements. Mountains composed 
 of such irregular beds of lava are of frequent occurrence in the region 
 under discussion. A fine example is seen in the vicinity of the town of 
 Beaver, Utah Territory, in what are known as the Tu-shar Mountains. 
 
 X. VOLCANIC STRUCTURE. 
 
 When many eruptions come successively from the same vent, and each 
 is a comparatively small amount, cones are built. Cones of such simple 
 structure are of frequent occurrence in the region under discussion. Great 
 complex cones such as are found in other parts of the world do not occur, 
 but a few double and one triple cone has been observed. The great majority 
 of the cones observed are built of cinders on broad sheets of lava, and are in 
 fact concomitant forms of lava mesas. Such cones are comparatively ephem- 
 eral, as the scoria and ashes of which they are composed yield readily to atmos- 
 
20 THREE GEOLOGICAL PROVINCES. 
 
 pheric degradation. Where such a cone exists, still having a well defined 
 crater, its condition testifies to the lateness of its origin, and all the facts 
 relating to the sheet of .lava on which it rests fully corroborate the conclu- 
 sion. From such evidence we are able to infer the recency of ,much of the 
 volcanic activity in the three provinces. If the human history of America 
 could be carried back to as early a date as it has been in Asia, it cannot be 
 doubted that the earlier chapters of that history would be replete with the 
 accounts of volcanic fires. 
 
 XL HENRY MOUNTAIN STRUCTURE. 
 
 Sometimes we find the sedimentary strata displaced by a quaquiversal 
 upheaval and the same fractured, and through these fractures floods of lava 
 have poured, and these may lie in patches about the flanks of the mount- 
 ains, or stand in dikes where the walls of the crevice have been swept away 
 by denudation. In the Henry Mountains we have a fine illustration of this 
 type of structure. These mountains have been studied by Mr. Gilbert 
 during the past season, and in his preliminary report he says : " The erup- 
 tions of the Henry Mountains are of a character entirely novel to me, and 
 they were studied with an interest stimulated by surprise. A description of 
 a single one, though it will not stand for all, will serve to. illustrate the type. 
 . Mount Ellsworth is round, and its base is six or eight miles broad. The 
 strata of the plain about it tire horizontal on every side. Near the 
 mountain the level strata become slightly inclined, rising from all sides 
 toward the mountain. At its base the dip steadily increases until on the 
 steep flanks it reaches a maximum of forty-five degrees. Then it begins to 
 diminish, and the strata arch over the crest in a complete dome. But the 
 top of the dome has cracked open, and tapering fissures have run out 
 to the flanks, and they have been filled with molten rock, which has con- 
 gealed and formed dikes. Moreover, the curving strata of sandstone and 
 shale have in places cleaved apart and admitted sheets of lava- between 
 them. So the mountain is a dome or bubble of sedimentary rocks witli an 
 eruptive core, with a system of radial dikes, and with a system of dikes in- 
 terleaved with the strata. It is a mountain of uplifted strata, distended Jind 
 permeated by eruptive rock." 
 
TYPES OF MOUNTAIN STRUCTURE. 21 
 
 In the foregoing characterization of certain types of structure found in 
 these regions, I have not attempted to adopt a system of exact classifica- 
 tion, which should be both inclusive and exclusive as the types do not 
 admit of such classification. No " hard and fast lines " can be drawn. I 
 have simply attempted to indicate the important types with their primary 
 and concomitant forms. 
 
 It is manifest that the structure of a sedimentary mountain will depend 
 primarily upon two elements the type of the displacement and the char- 
 acter and extent of erosion. The erosion may be antecedent or superim- 
 posed, or it may be consequent, or these methods may be combined, and 
 the erosion may be modified by dip, texture, and other characteristics of 
 the beds producing concomitant forms. 
 
 For convenience, I subjoin the following : 
 
 SYNOPSIS OF THE TYPES OF MOUNTAIN STRUCTURE 
 RECOGNIZED IN THE FOREGOING DISCUSSION. 
 
 MOUNTAINS COMPOSED OF SEDIMENTARY STRATA, AL- 
 TERED OR UNALTERED. 
 
 I. APPALACHIAN STRUCTURE. 
 
 (Not found in the three provinces.) 
 
 II. SIMPLE ANTICLINAL STRUCTURE. 
 
 Primary topographic form. Plateau with rounded vertical outline. 
 Concomitant forms : 1. Monoclinal Ridges on the Flanks. 
 
 .2. Monoclinal Ridges only. 
 
 3. Inclined Plateaus. 
 
 III. UINTA STRUCTURE. 
 
 Primary topographic form. Plateau with rounded summit and abrupt 
 shoulders on the flank. 
 
22 THREE GEOLOGICAL PROVINCES. 
 
 Concomitant forms : 1. Subsidiary Plateaus. 
 
 2. Projecting Ridges. 
 
 3. Axial Peaks. 
 
 4. Flanking Peaks. 
 
 5. Interrupted Monoclinal Ridges. 
 
 IV. KAIBAB STRUCTURE. 
 
 Primary topographic form. Plateau with angular outlines. 
 Concomitant forms : 1. Cliff's of Displacement. 
 
 2. Slopes of Displacement 
 
 3. Interrupted Monoclinal Ridges on the .Flanks. 
 
 4. Monoclinal Ridges with Plateau Carried Away. 
 
 5. Projecting Ridges. 
 
 6. Cliffs of Erosion. 
 
 7. Buttes. 
 
 8. Cameo Mountains. 
 
 V. BASIN RANGE STRUCTURE. 
 
 Primary topographic form. Monoclinal ridges of displacement. 
 Concomitant forms : 1. Monoclinal ridges on the back. 
 
 VI. ZONES OF DIVERSE DISPLACEMENT. 
 Topographic form. Irregular hills. 
 
 MOUNTAINS COMPOSED I WHOLE OR IN PART OF EX- 
 
 TRAVASATED MATERIAL. 
 
 VIL TABLE MOUNTAIN STRUCTURE. 
 
 VIIL UINKARET STRUCTURE. 
 
 IX. TU-SHAR STRUCTURE. 
 
 X. VOLCANIC STRUCTURE. 
 
 XI. HENRY MOUNTAIN STRUCTURE. 
 
MONOCLINAL RIDGES. 23 
 
 GEOGRAPHIC STRUCTURE GF THE BASIN PROVINCE. 
 
 . 
 
 In this province that orographic type which I have described as the 
 Basin Range structure prevails. 
 
 In the consideration of the structure of these ridge like mountains, it is 
 necessary to distinguish clearly the two more important elements involved, 
 viz, that of the metamorphic and unaltered sedimentary formations, and 
 that of the eruptive beds. 
 
 The former appear in simple monoclinal ridges of displacement, but 
 the extravasated material may occupy any position in relation to the simple 
 ridges ; sometimes it is found appearing on the flanks, sometimes burying 
 portions of the ranges, sometimes extending in subequal masses in trans- 
 verse or oblique directions to the ridges proper, and in many ways compli- 
 cating the topographic structure. It is of the structure of the monoclinal 
 ridges only that I now speak. These ridges are not residuary fragments of 
 anticlinal flexures eroded in intaylio, for wherever the structure at the foot 
 of the escarpment is not concealed by subaerial gravels, the beds .seen at 
 the summit of the ridge, or known to belong to a still higher horizon, appear 
 again at the foot of the escarped face, showing that they have been thrown 
 to that position by a fault. The ridges themselves occupy the place of max- 
 imum upheaval. In the summer of 1870 I had some opportunity to examine 
 a few of these ridges while oil a trip from Salt Lake City to Fillmore, Bea- 
 ver, and Saint George, in Utah. In the winter of 1871-72, I spent a few 
 weeks studying the mountains west of the Rio Virgen, and again in 1873 
 while engaged in prosecuting some ethnographic studies I visited many 
 points in Western Utah, Nevada, and Southern California, making cursory 
 examinations of mountain structure on my way; but Mr. G. K. Gilbert, 
 while engaged as geologist of the Wheeler expedition, made a much more 
 thorough study of this region. In his report of the geology of that region 
 for 1872, and published in 1874, page 50, under the head of "Mountain 
 Building/' Mr. Gilbert presents a "diagram of generalized mountain sections 
 discounting denudation," which I reproduce (Fig. 7), preserving his lettering. 
 
24 
 
 THREE GEOLOGICAL PROVINCES. 
 
 In explanation of the diagram Mr. Gilbert remarks: 
 "The sections accumulated by our geological observers admit of the 
 following classifications: 
 
 A B C D E F 
 
 "1. Faulted nionoclinals occur, in which the strata on one side of the 
 fault have been lifted, while those on the opposite side either do not appear 
 A), or (less frequently) have been elevated a less amount (B). Two-thirds 
 of the mountain ridges can be referred to this class. 
 
 "2. Other ridges are uplifts limited by parallel faults (C), and to these 
 may be assigned a few instances of isolated synclinals (D), occurring under 
 circumstances that preclude the idea that they are remnants omitted by 
 denudation. 
 
 "3. True anticlinals (E) are very rare, except as local, subsidiary fea- 
 tures, but many ranges are built of faulted and dislocated rock masses (F), 
 with an imperfect anticlinal arrangement. 
 
 "Not only is it impossible to formulate these features, by the aid of any 
 hypothetical denudation, in such a system of undulations and foldings as the 
 Messrs. Rogers have so thoroughly demonstrated in Pennsylvania and Vir- 
 ginia, but the structure of the Basin Range system stands in strong contrast 
 to that of the Appalachians. In the latter, corrugation has been produced 
 commonly by folding, exceptionally by faulting; in the former, commonly 
 by faulting, exception " '-Hy by flexure. In. the latter, few eruptive rocks occur; 
 in the former volcanic phenomena abound, and are intimately associated with 
 ridges of upheaval. The regular alternations of curved anticlinals and syn- 
 clinals of the Appalachians demand the assumption of great horizontal dimi- 
 nution of the space covered by the disturbed strata, and suggest lateral 
 pressure as the immediate force concerned; while in the Basin Ranges, the 
 displacement of comparatively rigid bodies of strata by vertical or nearly 
 vertical faults involves little horizontal diminution, and suggests the appli- 
 cation of vertical pressure from below." 
 
 Thus a characteristic range of this country is the edge of a great block 
 
GEOGRAPHIC STRUCTURE OF THE PLATEAU PROVINCE. 25 
 
 upheaved by the production of a fault and part passu with the upheaval, 
 eroded into irregular forma and modified by flows of eruptive matter from 
 beneath. While this is the general structure throughout the region under 
 consideration, there are many exceptions, as indicated by Mr. Gilbert. Of 
 especial interest are the "uplifts limited by parallel faults (G), and to these 
 maybe assigned a few instances of isolated synclinals (D), occurring under 
 circumstances that preclude the idea that they are remnants omitted by 
 denudation," and the "many ranges built of faulted and dislocated rock- 
 masses (F) with an imperfect anticlinal arrangement." 
 
 Perhaps the latter are what I have called Zones of Diverse Displace- 
 ment. 
 
 In the northern portion of the province other modifications of the gen- 
 eral structure seem to appear. Mr. King, in the third volume of the "Geo- 
 logical Survey of the Fortieth Parallel," page 451, says: "These low mount- 
 ain chains which lie traced across the desert with a north and south trend 
 are ordinarily the tops of folds whose deep synclinal valleys are filled with 
 Tertiary and Quaternary detritus." 
 
 That there should be exceptions to the general type of structure in this 
 province is not strange, for similar exceptions occur in each of the other 
 provinces, as will appear hereafter; but I have myself seen no true- anticlinal 
 
 mountains in the Basin Province. 
 
 \ 
 
 The mountains of eruptive origin in this province are chiefly accessory 
 masses to the simple ridges of upheaval, and so far as my observations 
 extend, are of the Tu-shar type. 
 
 OROGRAPHIC STRUCTURE OF THE PLATEAU PROVINCE. 
 
 In the Plateau Province the Kaibab structure prevails, but other types 
 of structure are found. The Uinta Range, which furnishes the type for the 
 Uinta structure is found within this province, and a number of simple anti- 
 clinals have been discovered ; we have also found many Zones of Diverse 
 Displacement. 
 
 The mountains of eruptive origin are of all the types above mentioned ; 
 table mountains have been observed in the region drained by the Grand, 
 White, and Yampa Rivers. Pilot Butte has already been mentioned, and 
 
26 THREE GEOLOGICAL PROVINCES. 
 
 other mountains of this type are found m the Sevier district The Uinkaret 
 Mountains, which have been t :ken as a type of structure, are on the north 
 side of the Grand Canon of the Colorado. San Francisco Mountain and 
 other mountains in that vicinity are known to be of this structure, but this 
 great group of mountains, of which San Francisco Mountain is the culmi- 
 nating peak, has not been sufficiently studied to enable us to characterize 
 them. The Navajo Mountain, Sierra la Sal, and others in this region are 
 knoAvn to be of the Henry Mountain type. 
 
 The principal number of important peaks and great mountain masses 
 of the Plateau Province are divided about equally between the last two 
 classes. Some mountains of the Tu-shar structure are found in the Sevier 
 district. Volcanic cones are found in great numbers throughout the south- 
 ern portion of the province. 
 
 GEOGRAPHIC STRUCTURE OF THE PARK PROVINCE. 
 
 The great mountain masses of the Park Province, especially those to 
 the north standing about the South, Middle, and North Parks, which I have 
 myself seen, are composed of metamorphic crystalline schists. It would 
 appear that these schists were metamorphosed antecedent to the deposition 
 of the Paleozoic, Mesozoic and Cenozoic rocks, which are found in many 
 places resting unconformably upon them ; for all these later sedimentary 
 beds contain to a greater or less extent conglomerates which are composed 
 of fragments of metamorphic materials resembling those of the principal 
 mountain masses ; and it further appears from my brief studies that this 
 series of rocks was profoundly plicated, perhaps on the Appalachian type, 
 i. e., with closely appressed folds, and this also prior to the deposition of the 
 upper sediments. Through Paleozoic and Mesozoic times minor changes of 
 level have occurred, now lifting the area above the sea, now submerging it, 
 so that many gentle unconformities are found with an interrupted succes- 
 sion of sedimentary beds. But the last great orographic displacements 
 are represented by broad upheavals which appear to have the structure of 
 the Uinta Mountains, so far as can be made out from the fragmentary 
 evidence left by the great erosion to which the country has been subjected 
 
MB. MARVINE ON THE PARK RANGE. 27 
 
 in late geological times. The plateau like structure of these great ranges 
 with sedimentaries dipping at high angles on their flanks, sometimes recurved 
 so as to cause inversion of the succession of strata, was a feature which 
 made a deep impression upon me in my travels through this country some 
 years ago, and in my imagination I continued the later sedimentary beds 
 in high curves over these plateaus, and dimly conjectured that tens of 
 thousands of feet had been eroded from some of the ranges, and that the 
 table or plateau like character of the ranges was due to some epoch of this 
 later denudation of the ranges when they were planed down to a common 
 level under conditions which I have explained in the volume several times 
 quoted. Such a planing down occurs when the channels of the eroding 
 streams remain for a great length of time at a general base level. But 
 when I came to study the Uinta Mountains it seemed to me that all the facts 
 which I had observed in the Park Province were duly explained by sup- 
 posing that that province had the same structure as that observed in the 
 Uinta Mountains. Since my study of that country Mr. Arch. R. Marvine 
 has made a much more thorough and careful survey of it as one of the 
 members of Dr. Hayden's corps. In the report of the United States Geo- 
 logical and Geographical Survey of Colorado, 1873, Hayden, on page 188, 
 Mr. Marvine, under the head of " Blue River or Mount Powell Group", 
 says : " 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 rectangu- 
 lar 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 southwestern side of the 
 mass, and from it the valleys and their sharp separating 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 la^ge ridges of the range have a similar structure. These 
 rugged ridges, in their easternmost portions, present a pretty uniform gen- 
 eral elevation, 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 
 
28 THREE GEOLOGICAL PROVINCES. 
 
 sharp ridges are but the remnants left 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 northern 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 lowered spur does not con- 
 tinue on as a sharp ridge but slopes off, a flat surfaced, plateau like area, 
 descending gently eastward. Since, upon the corresponding area at the 
 base of the northernmost ridge, great quantities of debris of the Lower 
 Cretaceous 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 adjacent regions on the 
 great Colorado Plateau of Northern Arizona, though there the sedimentary 
 beds have not (by many a thousand feet) been stripped by erosion from off 
 the underlying rocks. It is a form of mountain building which I think is 
 not uncommon in the West." 
 
 I am inclined to think that the purposes of orology will be better sub- 
 served by classing this structure as a type distinct from that of the Kaibab 
 structure, rather than as a modification of it. The general arching of the 
 strata between the lines of maximum flexure or faulting, allies it some- 
 what to a true anticlinal ; and so far as my studies go these lines of great- 
 est flexure have many more complexities than the faults and monoclinal 
 flexures usually found in the Plateau Province. Hence I have classed it as 
 a distinct type and called it the Uinta structure. 
 
 We already know that the spaces between the broad upheavals, of 
 which the ranges themselves are composed, are complicated by many anti- 
 clinal and synclinal flexures and by many faults, but the whole structure of 
 
STRUCT OB.- A L CHARACTERISTICS OF THREE PROVINCES. 29 
 
 the parky, as these interspaces are often called, is exceedingly complex, and 
 much study is necessary, and a great accumulation of facts must be obtained 
 before any safe generalization can be made ; but these interspaces or park 
 areas are sometimes Zones of Diverse Displacement. 
 
 Atlas Plate No. G presents a section across three of the great ranges of 
 the Park Province. This section has been prepared for me by Mr. Marvine. 
 The scale on which it is drawn does not admit of great detail, but the gen- 
 eral orographic characteristics are well represented. In a single section it 
 is impossible to present all of the facts upon which this generalization is 
 based. In the quotation from Mr. Marvine already given some of the facts 
 on which his opinions are based appear, and I have myself seen patches of 
 sandstone high up on the Front Range in the vicinity of Long's Peak, and 
 also on the northern end of the Park Range in an area of country not visited 
 by Mr. Marvine, but the shreds of evidence are too multifarious to be assem- 
 bled here. The park spaces between the great ranges are seen to be com- 
 plex in the section, but the full extent of this complexity could be illustrated 
 only by the most full and graphic representation. Doubtless when the 
 reports of the several members of the First Division of the United States 
 Geological and Geographical Survey of the Territories are published, the 
 general structure of this country will be more fully revealed. 
 
 I have quoted Mr. Marvine and discussed this subject with him more 
 fully from the fact that he and I have visited many of the same points. 
 
 I have not myself studied the eruptive mountains of this province. 
 
 SUMMARY OF THE STRUCTURAL CHARACTERISTICS OF 
 THE THREE PROVINCES. 
 
 The Basin Province is characterized by north and south ranges that are 
 monoclinal ridges of upheaval, and these monoclinal ridges are separated by 
 stretches of subaerial gravels that mask the structure of the areas of subsi- 
 dence. But while this is the prevailing structure, other types are found. 
 
 In the Plateau. Province the Kaibab structure is the characteristic. 
 Here on a grand scale the primary and concomitant forms are found; but 
 
30 THREE GEOLOGICAL PROVINCES. 
 
 Simple Anticlinals, the Uinta structure, and Zones of Diverse Displacement 
 are found as exceptional types. 
 
 In the Park Province the Uinta structure prevails and its primary and 
 concomitant topographic forms are grandly shown. Doubtless a more thor- 
 ough study of this region will result in the discovery of exceptional types. 
 
 THESE PROVINCES NOT SEPARATED BY WELL DEFINED 
 
 LINES. 
 
 No line of demarcation can be drawn between the Plateau Province 
 and the Park Province. There is an irregular belt of country separating 
 the better defined portions of the two provinces, which is complicated by 
 characteristics belonging to each. The Kaibab structure of the plateaus 
 does not change abruptly into the Uinta structure, which prevails in the 
 latter province. In fact there are many areas lying along the border sepa- 
 rating the two provinces which are characterized by a great development 
 of eruptive beds, which serve to a greater or less extent to mask the oro- 
 graphic structure of the sedimentary beds. 
 
 In like manner on the south and west of the Plateau Province there is 
 a belt of country separating it from the Basin Province, itself forming a sub- 
 province of great interest. This region has already been the subject of much 
 study, and although these studies have not been completed, many facts have 
 been discovered from which we can with safety make some important de- 
 ductions. Through late Mesozoic and earlier Tertiary times there was an 
 old shore line here, now retreating eastward, now advancing westward. It 
 is a region of many movements by faulting and flexing, and during these 
 movements, in Tertiary times at least, many lavas were poured out, so that 
 we have many unconformities both abrupt and gentle, many shore deposits, 
 many faults and flexures and many beds of eruptive matter. But the north- 
 ern portion of the Basin Province is separated geographically as well as 
 geologically from the Plateau Province by the Wasatch Mountains which 
 constitute a distinct geographic system; but geologically it is but a northern 
 extension of the intervening belt which I have already described, charac- 
 terized as distinct from that by the fact that the movements of displacement 
 
ZONES OF DIVERSE DISPLACEMENT. 31 
 
 faulting and flexing- were on a grander scale and as a consequence of this 
 greater displacement, the accumulations of sediments are greater and the 
 unconformities more apparent and complex. Another consequence of the 
 greater displacement is that the deep lying metamorphic rocks are brought 
 up and .exposed by denudation, so that extensive groups of crystalline schists 
 and quartzites appear. 
 
 This geographic district, the Wasatch Subprovince, terminates on the 
 south at Mount Nebo, and is quite distinct geographically as well as geologi- 
 cally from the subprovince to the southward, which may be termed the 
 Sevier and Rio Virgen Sub-province. 
 
 Thus the Wasatch and Sevier districts separate the Basin and Plateau 
 Provinces, not by the introduction of new types of structure, but by a com- 
 bination of the types observed on either hand and being complicated by 
 conditions consequent on their forming for a long time the shore line be- 
 tween the two. In the Sevier portion of the belt the Kaibab structure pre- . 
 vails, while in the Wasatch portion the Basin Range structure prevails. 
 
 The great Wasatch Range presents a bold front to the west due^ in a 
 general way to a great fault or rather a series of faults such as I have de- 
 scribed as occurring in the Basin Ranges; but on the east or back slope of 
 the range the structure is complex. An irregular belt of country stretching 
 from the crest of the mountains eastward many miles is faulted and flexed 
 in many ways. 
 
 In the northeast angle formed by the Wasatch and Uinta Mountains 
 there is a long but narrow and irregular zone stretching toward the north- 
 east from the head- waters of the Bear River. Sulphur Creek drains a part 
 of this, and the well known Bear River coal lands are found in the district. 
 From Aspen to a point near Carter, the Union Pacific Railroad runs along 
 the eastern border of the belt. Its extension in either direction beyond the 
 points indicated are unknown to me. This belt also exemplifies what I 
 have called Zones of Diverse Displacement, and the general effect is upheaval. 
 The belt seems to have been broken into very irregular blocks by lines of 
 faulting or flexure which so far as my observation has extended preserve 
 no law of direction. 
 
 The blocks into which the country has been broken have been tilted, 
 
32 THREE GEOLOGICAL PROVINCES. 
 
 greatly sometimes, sometimes turned quite on edge, and even in some cases 
 reversed. One of these blocks standing on edge afforded Professor Meek 
 the opportunity to make his section on Sulphur Creek published in Dr. Hay- 
 den's Report on the Geological Survey of Montana, Idaho, Wyoming, and 
 Utah, 1872. Professor Meek evidently recognized the difficulty of correlat- 
 ing the strata in that section with those outcropping elsewhere in the dis- 
 trict. I mention these excessively complex zones without attempting to 
 explain them. Some student of geology will eventually find here a subject 
 rich in results. 
 
 SUMMARY OUTLINE OF THE HISTORY OF THE THREE 
 PROVINCES DURING CENOZOIC TIME. 
 
 In the latter part of Mesozoic time the greater part of the .Basin Province 
 was dry land. The Plateau Province was an open but shallow sea. In 
 the Park Province a chain of islands extended to the south. The Cenozoic 
 time was inaugurated by a series of movements, which, continued to the 
 present time, have produced the topographic features now observed. This 
 part of the crust of the earth, and I mean by the term " crust" simply that 
 portion of the earth which we are able to study by actual observation in 
 truncated folds and eroded faults this portion of the crust, then, was gradu- 
 ally broken and contorted. The Plateau and Park Provinces were cut off 
 from the sea, and great bodies of fresh water accumulated in the basins, 
 while to the east in the region of the Great Plains, in earlier Tertiary times 
 at least, there was an open sea. Slowly through Cenozoic times the outlines 
 of these lakes were changed, doubtless in two ways : first, by the gradual 
 displacement of the rock beds in upheaval and subsidence here and there ; 
 and, second, by the gradual desiccation due to the filling up of the basins by 
 sedimentation and the erosion of their barriers ; and the total result of this 
 was to steadily diminish the lacustrine area. But the movements in the dis- 
 placement extended over the Basin Province, for that region was then a 
 comparatively low plain, constituting a general base level of erosion to 
 which that region had been denuded in Mesozoic and early Tertiary time 
 when it was an area of dry land ; for I think that from the known facts we 
 may reasonably infer that the Basin Ranges, though composed of Paleozoic 
 
THE THREE PROVINCES DURING CENOZOIC TIME. 33 
 
 and Eozoic rocks, are, as mountains, of very late upheaval. For some pur- 
 poses, and in broad generalization, erosion furnishes a valuable measure of 
 geological times. A mountain, as a mountain, is comparatively ephemeral. 
 The evidence of this is found on every hand as we study the Rocky Mount- 
 ain region. There can be no conclusion reached from reasoning on 
 geological data more certain than that the Uinta upheaval began at the close 
 of Mesozoic time, and has continued intermittently near to the present, and 
 during that time this- upheaval has suffered a degradation in areas of maxi- 
 mum erosion of no less than 30,000 feet; and there is evidence also which 
 leads to the conclusion that the conditions for great erosion were not per- 
 sistently maintained during this time. I have already stated that the Basin 
 Ranges occupy the area of maximum upheaval, and they are monoclinal 
 ridges. Had these ridges been upheaved greatly beyond their present 
 altitudes it is manifest that erosion would have carried them far back from 
 the lines of faults, a condition not found to obtain. 
 
 In the erosion of these ridges, as an independent subject of study, the 
 geologist is impressed with the magnitude of the work which has been per- 
 formed by atmospheric agencies. It appears that each ridge is but a small 
 residuary fragment of the great inclined block, and the interrange spaces are 
 filled with clays, sands and gravels, the waste of these blocks, in such a 
 manner as to bury the underlying rocks over broad areas ; and whether we 
 consider the amount which has been lost from the blocks or the amount 
 which has been accumulated in the valleys, the loss here or the gain there, 
 this transferred material is very great. It is worthy of remark that over 
 much of the area, the deposit of this transferred material in the valleys was 
 subaerial, but in the northwestern portion of the province it was lacustrine. 
 
 But when we compare the erosion which these inclined blocks have 
 suffered with that of many of the great blocks in the Plateau Province of 
 the Kaibab structure, or with that of the Uinta uplift, or with the great 
 uplifts in the Park Province, the erosion of the Basin Range ridges sinks 
 into insignificance. And when we consider, further, that the erosion in the 
 Plateau and Park Provinces which we are able to study has all been per- 
 formed during Cenozoic time, and that the conditions of maximum erosion 
 
 were but- intermittent during that time, we are forced to the conclusion that 
 3 P G 
 
34 T11IJEE GEOLOGICAL PKOVINCES. 
 
 the conditions for great erosion now found in the Basin Ranges have existed 
 but for a short period,-*-, e., the blocks were certainly not upheaved ante- 
 cedent to Cenozoic time ; and it would seem probable that it must have been 
 in late Tertiary. 
 
 It seems proper to add here a remark concerning certain conditions of 
 erosion, though I have elsewhere discussed the subject more fully. 
 
 The lesser or greater rapidity of erosion depends chiefly upon three 
 conditions: first, elevation above the base level of erosion; second, the 
 induration of the rocks ; and, third, the amount of rain fall. But erosion 
 does not increase in ratio with the increase of the precipitation of moisture, 
 for increasing moisture serves to increase the protection derived from 
 vegetation. 
 
 Nor does induration greatly preserve rocks from erosion, for on most 
 exposures the action of the elements in disintegrating the rocks is in excess 
 of the power of the streams to carry the material away. The exceptional 
 exposures are found on steep slopes ; yet the difference in the induration of 
 beds has an effect as seen in the minor or concomitant forms of all mountain 
 regions. The principal factor in maximum erosion is elevation above the 
 base level, and the power of erosion increases in geometric ratio with the 
 elevation. The power of the streams to transport the material of erosion 
 is increased in geometric ratio and the power of the water in corrasion is in 
 like manner increased ; and the corrasion of deep channels by rapid streams 
 filled with sands, gravels and bowlders produces another condition of surface 
 favorable to general degradation that is, the walls of these deep channels 
 are broken down by gravity, which is further increased by an undermining 
 process where harder and softer beds alternate. With these facts in view, 
 we need not enter into a consideration of the difference of texture or indu- 
 ration of the rocks of the Plateau and Park Provinces and those of the 
 Basin Province ; but we may remark that of the 30,000 feet eroded from 
 the Uinta uplift, more than 16,000 feet were of beds of Paleozoic Age, and 
 with a texture as firm as the rocks of the Basin Ranges. 
 
 It is manifest that the result of all these movements of displacement in 
 the three provinces was general upheaval. But this upheaval in the three 
 provinces was unequal ; it was great in the Basin Province, greater in the 
 
THE DBAINAGE REVERSED. 35 
 
 Plateau Province, and greatest in the Park Province. The Basin Province 
 was already above the sea level, but a comparatively low plain. In such a 
 condition, erosion would be slight; and as the ranges were lifted, the mate- 
 rial derived from them was deposited in the valleys, and it is probable that 
 no considerable amount was transported beyond the province into the sea, 
 and the general uplift of the province was little or no greater than the 
 change from that of the low plain near the sea level to its present elevation 
 that is, the Basin Province as a body is not the result of the difference be- 
 tween erosion and elevation ; but the ranges themselves do thus mark the 
 difference between erosion and elevation. That which was taken from the 
 mountains was added to the valleys. Much of the Plateau Province was 
 still an area of rapidly accumulating sediments long into Tertiary time ; 
 but at last the movements which began at the commencement of Tertiary 
 time succeeded in bringing the whole area not .only above the level of the 
 sea, but above the general level of the Basin Province itself; so that while 
 the Basin Province was drained into the Plateau Province in earlier Tertiary 
 time, in late Tertiary time the drainage was reversed, and the streams of 
 the Plateau Province found their way to the sea by passing through the 
 Basin Province, and many of them, especially those in the Sevier and 
 Wasatch regions which head along the old shore line, are now drained into 
 the basins which characterize the province thus designated. 
 
 It is the opinion of Mr. llowell, and I believe also that of Captain 
 Dutton, that this drainage was in some cases reversed along the very channels 
 occupied by the ancient streams which ran from the Basin Province into 
 the Plateau lakes. In the Park Province the general upheaval was still 
 greater, and the Colorado River, which empties into the Gulf of California, 
 heads in the very heart of the Park Province and drains the greater part of 
 the Plateau Province by carrying its waters across the Basin Province. 
 While the general surface of the last two mentioned provinces was in 
 Mesozoic time not above the level of the sea, at the present time the general 
 surface is from four to fourteen thousand feet above the sea level ; but there 
 are portions now marked by great ranges which have been upheaved twenty 
 and thirty thousand feet ; but these portions during the progress of upheaval 
 suffered denudation, and a part at least of the material thus denuded was 
 
36 THEEE GEOLOGICAL PROVINCES. 
 
 not carried away to the sea but was deposited in fresh water basins. But 
 at last these fresh water basins themselves were drained and their beds 
 faulted and flexed and eroded, and their sites are now found marked by 
 broad stretches of bad-lands. 
 
 I speak of an open sea to the east of the Park Mountains, where now 
 the Great Plains stretch in broad expanse. That there was a sea or arm of 
 the sea here is manifest, for I have collected marine Tertiary fossils of 
 Vicksburgh types in several places east of Denver; but from my exceed- 
 ingly brief studies in that region, merely as a passing traveler, I can only 
 say that the region, though simple in its topographic features, is indeed 
 complex in its geological structure. 
 
 Throughout this great area, from the eastern slope of the Park Moun- 
 tains on the east to the eastern slope of the Sierra Nevada on the west, and 
 from the sources of the Green and Shoshoni Rivers on the north to the 
 San Francisco Mountains on the south, the whole region is broken, flexed, 
 and contorted along innumerable lines. But the great structure lines have 
 a north and south trend ; the ranges of the Basin Province run from north 
 to south ; the great faults of the Plateau Province also run north and south, 
 and the Park Ranges have a north and south trend. But these general 
 outlines are broken by oblique and transverse displacements, usually of a 
 minor magnitude, though in some cases, as in the Uinta Mountains, these 
 transverse displacements assume as great proportions as the north and south 
 flexures and faults. While the whole region is exceedingly complex by 
 displacement, it is also exceedingly complex by reason of the unconformity 
 of its sedimentary beds. And all this complexity is greatly increased by 
 reason of the floods of lava which have been poured out here and there 
 over the entire area, and now and then through Cenozoic up to the present 
 time. And all these floods of lava, all these, thousands of eruptive moun- 
 tains, thousands of mesa sheets, thousands of volcanic cones, testify to a 
 period of great volcanic activity while the region was in fact a great conti- 
 nental area, thus contradicting the generalization which has obtained in some 
 quarters that volcanic activity is adjacent to the sea. And further, very 
 much of this volcanic activity has been exhibited since the desiccation of 
 the lakes. 
 
OHA.PTBR II. 
 
 SEDIMENTARY GROUPS OF THE PLATEAU 
 
 PROVINCE. 
 
 We turn now to a consideration of the Plateau Province. Throughout 
 its extent it is -traversed by profound gorges or canons ; high cliffs are 
 found ; long ridges and lone buttes are seen, all presenting escarpments 
 unclad with vegetation where the geological structure is plainly revealed, 
 and it is nowhere concealed to any important extent by subaerial gravels, 
 river deposits, deep soil, or rich vegetation. The whole region has been flexed 
 and faulted on a vast scale ; the flexures are truncated by erosion, and the 
 faults are crossed by canons and lines of cliffs ; and thus by a combination 
 of circumstances the whole region is an open book to the geologist, revealing 
 a wonderfully complicated structure and a grand succession of formations. 
 Accumulations of sediments may be studied of Cenozoic, Mesozoic, and 
 Paleozoic Ages, each represented by formations that are measured by thou- 
 sands of feet. In the hearts of the mountains and depths of the canons 
 Eozoic rocks are found ; on the mesas and elevated valleys sheets of lava 
 have been spread; and naked volcanic cones crown the geological series. A 
 general section of the sedimentary beds alone sums up a total of nearly 
 60,000 feet, and the relations of the groups into which they can be divided 
 can be determined with a certainty rarely attainable in the eastern portion 
 of the United States. When we group these beds in such a manner as the 
 structural geology demands we have a series of groups or succession of 
 formations separated by epochs of change, producing unconformities or 
 resulting in extensive stratigraphic peculiarities, and in constructing a 'gen- 
 eral section of this country this natural series cannot be ignored without 
 
 37 
 
38 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 greatly distorting the facts. But a section thus arranged presents a series 
 of limestones, shales, sandstones and conglomerates totally unlike that 
 which has been established in the New York and Appalachian Province or 
 in the Valley of the Mississippi. Again in several of the groups we dis- 
 cover the remains o t f rich faunas and floras, but the series of fossils belonging 
 to any of the natural groups in the Plateau Province is unlike that of any 
 group or formation in the earlier studied rocks of the east ; either entirely 
 new series are found or the old types are regrouped so as to present a new 
 aspect. Hence it would be manifestly absurd to introduce into this newly 
 studied province the nomenclature adopted in those provinces which had 
 been previously studied, as it would involve the necessity of explaining in 
 each case that the name was used with a new meaning, and that the adop- 
 tion of the older names was intended simply to express the opinion that the 
 group to which it was given should be referred to some period in the geo- 
 logical time scale about the same as that held by the group to which the 
 name was originally applied ; and this would involve the re-adjustment of 
 the names from time to time on the collection of new suites of fossils. While 
 it does not seem possible to consider a particular sandstone or limestone, or 
 a particular group of strata as identical with or closely similar to one in 
 New York or Illinois, this does not preclude the possibility of establishing a 
 general synchronism. The Cenozoic, Mesozoic and Paleozoic Ages seem 
 to l)e as well defined as elsewhere, and in each age there are formations 
 which are earlier or later, but the details of this general synchronism can 
 only be discovered after a far more thorough study of the paleontology of 
 the province has been made. 
 
 The conclusions thus stated have been reached after a stud}' of the 
 province which ' has occupied the greater part of the last eight years. 
 During the earlier years I attempted here to find the formations of the 
 east, or at least formations corresponding to them, and thus years of study 
 were in part fruitless for that reason. I then determined if possible 
 to discover the natural series of the province itself independent of 
 other regions, and the general section below is the result. Perhaps, from 
 a priori reasons, I should have commenced with this plan. The supposi- 
 tion that at the same time sediments should have been carried into the 
 
NAMES OF THE GEOUPS. 39 
 
 Colorado sea similar to those in the New York sea, is not warranted by a 
 study of the deposits now forming in existing seas. The Hudson River 
 carries a very different deposit into the Atlantic Ocean from that carried by 
 the Colorado River into the Gulf of California. Nor should we expect that 
 the faunas or floras of regions so widely separated should be the same or 
 closely similar. In the earlier times, which we study as geologists, there 
 seem to have been physical conditions in the two regions as widely differing 
 as those of the present. The Cenozoic formations of the plateaus are lacus- 
 trine ; the Cenozoic formations of the Atlantic slope are marine. The Meso- 
 zoic of the plateaus is of great extent and thickness, while that age is but 
 scantily represented on the Atlantic slope. Nor do the Paleozoic forma- 
 tions exhibit a close similarity. 
 
 The names which I have selected for the groups are geographic, as 
 such a system admits of easy interpolation, and the localities serve well in 
 fitting the name to the group and refer at once to the typical strata. For 
 obvious reasons I should have been pleased to have commenced with a 
 clean slate, selecting such localities as would serve for the best types ; but 
 I did not feel at liberty to ignore the labors of geologists who had pre- 
 ceded me. 
 
 In the Cenozoic groups and the first Mesozoic I found great confusion, 
 as these groups had been seen at many places, and some of them received 
 several names each ; and often different groups were confounded by being 
 included under one geographic name. With these groups I have tried to 
 select such localities as would serve to fairly represent the groups and at 
 the same time do no injustice to other laborers. 
 
 We now append the general section. 
 
40 
 
 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 TABLE OF THE GROUPS OF SEDIMENTARY STRATA OF 
 THE PLATEAU PROVINCE. 
 
 Scale in 
 feet. 
 
 2, 000 
 
 4,000 
 
 6,000 
 
 8, COO 
 
 10,000 
 
 12, 000 
 
 14, 000 
 
 i 
 
 300 
 
 1,800 
 
 2,000 
 
 500 
 
 800 
 
 3, 000 
 
 1,800 
 
 1,800 
 
 2,000 
 
 
 Groups. 
 
 Bishop Mt Conglo 
 
 Brown's Park. 
 
 Bridger. 
 
 Upper Green Rivei 
 
 Lower Green River 
 
 Bitter Creek. 
 
 Point of Hocks. 
 
 Salt Wells. 
 
 Sulphur Creek. 
 
 Uriconformable by i)li< 
 
 .th underlying rocks. 
 
 Sandstones, gravels, limestones, concretionary 
 and stratified flints. Unconformable with all 
 underlying rocks. 
 
 Bad-land sandstones, (chiefly green-sands,) lime- 
 stones, shells marls, -and concretionary and 
 stratified flints. 
 
 Shnles, often bituminous; sandstones and lime- 
 stones ; carbonaceous shales and lignitic coal 
 near the base. 
 
 Bad-laud sandstones, often with much gypsum ; 
 indurated sandstones; ferruginous; shell- 
 marls ; many beds of carbonaceous shales and 
 lignitic coal. To the southward the group is 
 composed of indurated sandstones and lime- 
 stones. Uiicoiiformablc by plication and ero- 
 sion with the next. 
 
 Upper Hogback 
 Sandstone. 
 
 Middle Hogback 
 Sandstone. 
 
 Golden Wall 
 Sandstone. 
 
 Sandstones, usually indurated, 
 sometime ferruginous, with 
 many beds of carbonaceous 
 shales and lignitic coal. 
 
 Sandstones or arenaceous shales; often very 
 friable, producing bad-lands, with carbonaceous 
 shales arid lignitic coal. 
 
 Black shales; occasionally friable sandstones 
 with carbonaceous shales and lignitic coal. 
 
 Henry's Fork. 
 
 Sandstones, bad-laud rocks, conglomerates, and 
 
 shales, with carbonaceous slriles and lignitic coal. 
 
 ' Unconformable by erosion with the next. 
 
TABLES OF THE GROUPS. 
 
 41 
 
 MESOZOIC. 
 
 JURA AND TRIAS. 
 
 2,000 
 4,000 
 6,000 
 8,000 
 10, 000 
 12, 000 
 14, 000 
 
 
 i, aoo 
 
 Flaming 
 Gorge. 
 
 l!ad-land sandstones, sftnetimes argillaceous, with much gypsum ; massive sandstones 
 and limestones. Three members of this group deserve special mention. A bed of 
 limestone has been found at the base of the group wherever it has been studied 
 varying from 10 feet to 200 feet in thickness. In Southern Utah it caps an extensive 
 escarpment known as the White Cliffs, and we have called it the White Cliff Lime- 
 stone. In other localities a limestone more or less arenaceous is found of about the 
 some thickness ; this limestone is about midway in the group. We have called it 
 the Mid-Group Limestone. Immediately underlying! hi?, in more northern localities 
 a massive sandstone is found, from 400 to 600 feet in thickness. Farther to the soutl 
 this massive sandstone is represented by bad-land sandstones with clny and gypsum 
 
 
 
 
 " '.' ': :; - : }^-- ' ~$-:.-K- A';;. 
 
 x <v=vcvr%d > ^ry ; 
 
 - 
 
 f^^^S^S~g&-f. 
 
 1,100 
 
 White Cliff. 
 
 Usually the entire group is a massive obliquely laminated sand- 
 stone often of a beautiful white or golden color, sometimes red. 
 In a few places rather heavily bedded sandstones are found. 
 
 
 
 
 
 '. .'-'-' : ' >' - -' H 
 
 
 1, 101. 
 
 Vermilion 
 Clitf. 
 
 Massive sandstones with ferruginous layers and often with thin, 
 irregular beds of chcrty limestone ; the massive beds sometimes 
 broken into thinner strata. 
 
 : O^~ : . '^'.^'*- " ^-' 
 
 - 
 
 ; :>r.VW.- ?-'. -'--W- 
 
 1 
 
 ^SipS& 
 
 1,800 
 
 Shiuarump. 
 
 Upper Dad-land sandstones with much gypsum ; often argillaceous ; someti-nea 
 Shinarump. indurated sandstones. 
 s liinarump ^ " ne rong'cimerate not easily recognized, toward the north, about SO 
 Connlom- (eet '" thinness, but increasing southward until it attains 200 feet. It 
 
 erate. is foumi cwP'oeanextensiveescarpmentknownastheShinarumpCliHs. 
 Bad-land sandstones with much gypsum; sometimes argillaceous; in a 
 Lower few P laces tne y are indurated sandstones ; sometimes unconformable 
 Shinarumn by erosion with the next. In such places a conglomerate is found at 
 the base composed of rounded and angular fragments of carboniferous 
 
 ana IP loio o oa o o w 
 
 
 
 8 
 
 o 
 
 N 
 
 o 
 
 
 
 <1 
 Pi 
 
 CARBONIFEROUS. 
 
 
 1,000 
 
 Upper Au- 
 brey. 
 
 Sandstones and limestones, the latter cherty. To the north there a'e two members of 
 this group; th upper is cherty limestone from 100 feet to 200 feet in thickness, which 
 we have called the Bellerophon Limestone. The lower, the Tampa Sandstone, is 
 very massive, rarely showing evidences of stratification ; in some places obliquely 
 laminated. Farther 8outhward cherty limestones prevail, and the whole group is 
 more minutely stratified. 
 
 -iiiii i i . . 
 
 
 1,000 
 
 Lower Au- 
 brey. 
 
 Sandstones and limestones massively bedded or shaly. In some 
 localities sandstones prevail and arc exceedingly friable. 
 
 .''' i i '> '.',',.' * 
 
 
 T7l7??7TTyT?^ 
 
 i i t ' i ' . __. 
 
 2,000 
 
 Red Wall. 
 
 Chiefly limestones. In the Uinta, Mountains massive limestones 
 are separated by thin strata of sandstones. In the Grand 
 Canon a massive limestone a thousand leet in thickness is 
 found, with thinner strata of limestone and sandstone beneath. 
 In the Uinta Mountains the group is conformable with the Lo- 
 dore series and unconformablo with the Uinta Sandstone. In 
 the Grand Caiion it is conformable with the Tonto Group. 
 
 
 j i i i__ 
 
 
 
 4(50 
 
 Lodorc. 
 
 Sandstones and shales : supposed to be the equivalent in the Uinta Mountains to the 
 Tonto Group in the Grand Canon. 
 
 
 
 12, 500 
 
 Uinta. 
 
 Sandstones; massive; thinly bedded, and shales; ferruginous; 
 some portions metamorphosed, becoming a quartzite. Uncon- 
 formablo by extensive plication and erosion on the Red Creek 
 Quartzite. 
 
 U-~d 
 
 - 
 
 -- ^j 
 
 - 
 
 v : .-.- : -.' .' \v-^- 
 
 
 
 
 -'"' ' ' " --^^ 
 
42 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 A quartzite with ImruhliMidic and micaceous schists, all 
 urcatl.y iinpl&atod. 
 
TABLES OF TOE GROUPS. 43 
 
 BASE OF THE SECTION IN THE GRAND CANON OF THE 
 
 COLORADO. 
 
 I Base of Red Wall Group. 
 
 Sandstones and shales, with a lew limestones ; uncon- 
 formable by extensive plication and erosion on the 
 next. 
 
 Sandstones, shales, and a few limestones. On further 
 study this group will probably bo subdivided. 
 
 Ilornl'lendic and micaceous schists and slates, -with 
 beds and dikes of granite. Thickness unknown. 
 Found at the bottom of the Grand Canon. 
 
44 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 REMARKS ON THE GENERAL SECTION. 
 
 The thicknesses which I have given in the table are considered to be 
 nearly an average. Many of the groups are much thicker in some places, 
 and thinner in others. If the maximum thickness of each had been given, 
 the sum would have been more than 70,000 feet; while if the minimum 
 had been given the sum would have been reduced nearly to 50,000 feet. 
 The Mesozoic and Paleozoic sediments in all latitudes where they have 
 been studied, are found to attenuate as you pass from the western to the 
 eastern border of the province. 
 
 In characterizing the rocks I have attempted to give only those 
 features which are general throughout the province so far as it has been 
 studied ; but there are many local peculiarities which we have observed 
 and which will appear in the detailed reports. 
 
 LOCALITIES WHERE THE SEVERAL GROUPS CAN BE STUDIED. 
 
 I now append a few localities where these several groups can be seen 
 under favorable circumstances. They might be multiplied greatly, but 
 perhaps no good purpose would thus be served. 
 
 BISHOP MOUNTAIN CONGLOMEEATE. 
 
 The Bishop Mountain Conglomerate can be seen on the summit of 
 Bishop Mountain, where it lies unconformably on the eroded beds of the 
 Bitter Creek Group. A fine exposure can also be seen on the summit of 
 the Quien Hornet Mountain. 
 
 BROWN'S PARK GROUP. 
 
 This group is well represented at Brown's Park, in Northeastern Utah 
 and Northwestern Colorado. 
 
 A good section can be obtained in the high bluffs on the west side of 
 the Snake River by commencing about five miles above its confluence with 
 the Yampa where these beds are seen to rest unconformably against Car- 
 boniferous strata at the foot of the mountain. In going north two minor 
 flexures are passed where the upper members of the group are exposed ; 
 and, on reaching a third and greater upheaval, the group is exposed from 
 summit to base, and is seen to rest unconformably upon Bridger beds. 
 
LOCALITIES WHERE THE GROUPS CAN BE STUDIED. 45 
 
 BEIDGER GROUP. 
 
 This group can be well studied in the vicinity of Fort Bridger, at 
 Church Buttes, and in the Cameo Mountains. It has an extensive 
 development in this region, i. e., west of the Green River and north of the 
 Uinta Mountains, and is usually well exposed. An outlying patch can be 
 seen between Vermilion Creek and the Snake River, on the north side of 
 the Dry Mountains. It can also be finely studied at Haystack Mountain. 
 
 
 
 UPPER GREEN RIVER GROUP. 
 
 The Plant Beds of this group are well exposed to the north of Green 
 River Station, and between that point and Alkali Stage Station in many 
 gulches and canons. They are also well exposed in the cuts of the Union 
 Pacific Railroad between Green River Station and Bryan. Another good 
 exposure can be seen in the escarpments on either side of Henry's Fork, 
 commencing about five miles above its mouth and continuing up the stream 
 for several miles. 
 
 The Tower Sandstone is well shown in the cliffs at Green River 
 Station and in that vicinity, especially up and down the river for several 
 miles. This sandstone is also well exposed on the eastern side of the Green 
 River, below the mouth of Currant Creek. 
 
 LOWER GREEN RIVER GROUP. 
 
 This group is. well exposed along the Green River from Green River 
 Station southward for ten miles where a detailed section has been made 
 and will be given hereafter. It is also well exposed in many of the escarp- 
 ments of the Quien Hornet Mountain. We again find it well exposed in 
 the escarpments a few miles northeast from the head of Vermilion Canon. 
 Fine exposures are seen on the Snake River six miles above the northern 
 foot of Junction Mountain. The elevated ledges known as Pine Bluffs, near 
 the sources of the eastern tributaries of Vermilion Creek, are capped with 
 the limestones and bituminous shales of this group. 
 
 BITTER CREEK GROUP. 
 
 This group is well exposed along Bitter Creek in the vicinity of Bitter 
 
46 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 Creek and Black Buttes Stations. A fine section- can be obtained by com- 
 mencing at Pine Bluffs at the foot of the limestone beds and passing in a 
 direction a little north of west until the massive gray sandstone of the next 
 group is reached. Across this stretch of country the beds dip to the east, 
 and their outcropping edges stand in a succession of ledges and can be well 
 studied. It is better to follow the line which I have indicated than to make 
 a section along Bitter Creek, as there is a fault passing between old Hall- 
 ville and Black Buttes Station, and it is difficult along that line to determine 
 the amount of the fault, and hence there is a liability of duplicating or omit- 
 ting some of the lower members of this section. This fault will be explained 
 hereafter. 
 
 The junction of the Bitter Creek Group with the Lower Green River 
 can be very well seen in the escarpment at Pine Bluffs; one hand can be 
 placed upon a limestone of the upper group and the other on a massive bad- 
 land sandstone of the lower. In like manner the junction between this 
 group and the next lower can be well seen in an escarpment east of and 
 facing Black Butte. There is an escarpment on the northeast side of Bitter 
 Creek, facing that stream and extending from Hallville Section House to 
 Point of Rocks, where the upper sandstones of the Point of Rocks Group 
 stand in an almost vertical cliff, and the lower members of the Bitter Creek 
 series can be seen to rest upon this sandstone unconformably. These beds 
 are exceedingly friable, ferruginous sandstones and shales, and in many 
 places a shelf or terrace is seen between the foot of the Bitter Creek shales 
 and the brink of the cliffs formed of the Point of Rocks sandstone. 
 
 This group can be studied along the Union Pacific Railroad west of Rock 
 Springs. Three-fourths of a mile east of Lawrence Section House the railroad 
 passes with an abrupt curve around a ledge of rocks, where the junction of 
 the Bitter Creek series and the Lower Green River can be plainly seen. 
 Here you may place your forefinger on a limestone of the Lower Green 
 River and your thumb on a bad-land sandstone of the Bitter Creek Group. 
 In the escarped hills on either side, the line between the limestones and 
 buff and pink sandstones can be plainly seen. These rocks dip to the west 
 at an angle of about four degrees, and as you go eastward this dip gradually 
 increases, and bed after bed of the Bitter Creek Group can be seen well ex- 
 
LOCALITIES WHERE THE GROUPS CAN BE STUDIED. 47 
 
 posed by passing back and forth among- the^hills until reaching' a point about 
 a mile and a half west of Blair's coal mine, you come to a high ridge or 
 hogback where the series ends. This hogback is composed of the upper 
 sandstone of the Point of Rocks Group; the junction of the two groups on 
 this line can be very well seen. The gray sandstone of the Point of Rocks 
 Group is massive and indurated. The brown, ferruginous . shales of the 
 Bitter Creek Group yield readily to atmospheric degradation, and have been 
 swept away back of the ridge or hogback, leaving broad, naked surfaces of 
 gray sandstone. 
 
 Another fine section can be obtained by commencing on the southern 
 face of the Quien Hornet Mountain and passing over the escarped ledges 
 in a southwesterly direction along the bluffs of Red Creek until you reach 
 the foot of the great hogback which is composed of beds of the Point of 
 Rocks Group. 
 
 Vermilion Creek in its upper course runs through beds of this group. 
 Its many wet-weather tributaries have carved the country with deep but 
 flaring channels, and the naked beds can be seen on every hand; and the 
 bad-land hills are filled with fossils; but the lower members of the group 
 cannot well be studied by reason of some complicated but interesting dis- 
 placements that are observed a little north of the Vermilion Cafion. These 
 displacements will be discussed hereafter. 
 
 To the southward this group of rocks is developed over broad areas. 
 The Cafion of Desolation for much of its course is cut through these rocks, 
 and in its high walls this group can be studied to advantage. The Pink 
 Cliffs of Southern Utah are of this age. 
 
 POINT OF ROCKS GROUP. 
 
 A good section of this group can be obtained at Point of Rocks Station. 
 There is a series of cliffs and abruptly escarped hills extending from a point 
 northeast of the station in a westerly direction for several miles. These 
 escarpments face Bitter Creek and the Union Pacific Railroad. In the cliff 
 immediately back of the depot at Point of Rocks the junction between the 
 Bitter Creek and Point of Rocks Groups is well seen. As I have already 
 described, the lower members of the upper groups are brown, friable, arena- 
 
48 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 ceous, ferruginous shales, with occasional beds of* soft sandstone, all weath- 
 ering easily; and the line of junction between that and the massive gray 
 sandstone which forms the summit of the Point of Rocks Group can be 
 plainly seen. In these shales immediately overlying the massive sandstone 
 there are beds and seams of coal. The first massive sandstone is the Upper 
 Hogback Sandstone. These rocks all have an easterly dip, and as you go 
 westward you soon reach the base of the Upper Hogback Sandstone, then 
 pass the beds of irregularly bedded shales and sandstones until you reach a 
 second massive, gray sandstone, which in many places is broken into two 
 or more beds. This is the Middle Hogback Sandstone. Still going west- 
 ward, massive and thinly bedded sandstones of yellowish-buff color alter- 
 nating with massive beds of light gray or white sandstone, are seen. About 
 six miles from the station -the railroad turns southward and debouches 
 from the narrow canon valley of* the Point of Eocks into the broad open 
 valley of the Salt Wells. To reach the base of the Point of Rocks Group 
 it is necessary to diverge from the railroad, which passes along the foot of 
 the cliffs, and eontinue in a westerly direction until the last massive gray 
 sandstone is reached. It will then be noticed that the massive beds, both 
 yellow and gray, have been passed, and that another series of more thinly 
 laminated beds underlie the massive series. These alternating beds of gray 
 and buff belong to the Golden Wall Group. The separation between these 
 two groups at this point is not as plainly marked as at many other regions. 
 The whole thickness at this locality is about 1,800 feet. 
 
 When Messrs. Meek and Bannister made their section along this line, 
 or their Point of Rocks Section, they commenced a few hundred feet below 
 the summit of the group and ended about 300 feet above its base, which 
 was not seen by them; for in turning southward with the railroad they 
 crossed two great faults having their throw to the north. The lines of fault- 
 ing pass along a valley showing no rock exposures, and when they passed 
 out into Salt Wells Valley they were on beds of the Salt Wells Group at a 
 horizon of six or eight hundred feet below the summit. 
 
 Another good section of this group can be obtained at Rock Springs. 
 A few hundred yards west of the mineral spring known as Rock Spring, a 
 great, massive sandstone stands in a ledge, the beds dipping to the west at 
 
LOCALITIES WHERE THE GROUPS CAN BE STUDIED. 49 
 
 an angle of about 1C degrees. The brown shales and sandstones of the 
 upper group have been stripped from this sandstone over broad areas, and 
 the junction between the two can be plainly seen. Starting from this point 
 and going eastward, a series of gray sandstones above, interrupted by car- 
 bonaceous shales and beds of coal, are passed; then gray and buff sand- 
 stones are seen until the Van Dyke Mine is reached. A little east of this 
 point we come to the base of the Point of Rocks Group, and reach the 
 summit of the Salt Wells Group. I have never examined this point with 
 sufficient care to enable me to indicate the exact junction, but as described 
 in the Point of Rocks Section above, the junction is not very well denned. 
 
 Fine sections can be obtained on either side of the Green River two 
 miles above Flaming Gorge where this group of beds was measured and 
 found to be 2,000 feet in thickness. Here they stand on edge, and their 
 stratification can be well seen. 
 
 The foot of Desolation Canon, and Gray Canon on the Green River 
 affords another fine section, and the group can be well studied in the Wa- 
 satch Cliffs at the head of the Escalante River, and in the hills at the foot 
 of the Pink Cliffs, in Southern Utah. 
 
 SALT WELLS GROUP. 
 
 Standing south of the debouchure of the Point of Rocks Canon into 
 Salt Wells Basin, and looking eastward, lines of cliffs and escarped hills are 
 seen. Climbing these hills until the first massive, light gray sandstone is 
 found, you reach the summit of the Salt Wells Group and the base of the 
 Point of Rocks. Then, turning westward you descend from this eminence, 
 and still continuing in a westerly direction you pass along the foot of an 
 escarpment which faces the railroad, the beds of which dip at an angle of 
 about 8 degrees to the east, and hence you are passing from higher to lower 
 strata. Still continuing 1 in this direction for several miles, and crossing- the 
 
 O 7 O 
 
 broad valley of Pretty Creek, you reach at last the axis of the upheaval 
 near Baxter Section House. Here we find an escarpment facing the 
 north, the rocks of which are light colored, arenaceous shales above and 
 dark, argillaceous shales below. The arenaceous shales are at the base of 
 the Salt Wells Group; the black shales below are believed to belong to the 
 4 P a 
 
50 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 summit of the next group. No examination of the section has been made 
 along this line nor have the beds been studied in detail, but the upper and 
 lower limits of the gfoup are tolerably well defined. On the Green River, 
 about two miles and a half above Flaming Gorge, the junction between the 
 black shales of the lower group and the yellow shales of the upper can be 
 well seen, and the junction between this group and the Point of Rocks 
 Group is also well seen. Here the beds stand on edge and were measured, 
 and a thickness of nearly 2,000 feet obtained. This group can be well 
 studied in narrow zones along the northern flanks of the Uinta Mountains. 
 Fine exposures occur in the Pink Cliffs and at Gunnison's Butte on the 
 Green River south of Gray Canon, and north of the point where that river 
 was crossed by Captain Gunnison on his trip to Utah in 1853. 
 
 SULPHUR CREEK GROUP. 
 
 This group of black shales can be well seen in the hills near Hilliard 
 Station on the Union Pacific Railroad. Here Sulphur Creek cuts through 
 them for several miles. In Professor Meek's "Section on Sulphur Creek 
 near Bear River," his "No. 1" is the summit of the group. The locality 
 does not present a good type from the fact of the great displacements to 
 which the beds have been subjected. Their relation to underlying beds can- 
 not be determined with certainty; but on the north and south sides of the 
 Uinta Mountains many fine exposures are found. I have already mentioned 
 the point where the junction of this group ,with the overlying can be seen, 
 north of Flaming Gorge; the beds dip to the north at an angle of nearly 
 90 degrees, and on the south side of Henry's Fork the junction of the black 
 shales with the next group is plainly seen. Here the beds were measured 
 and found to be 2,050 feet in thickness. . 
 
 Farther eastward between the head of Dry Lake Valley and Vermilion 
 Creek the beds dip to the north at an angle of about 25 degrees and are 
 truncated with the great Uinta flexure. Still farther south in the Escalante 
 Valley, Paria Valley, Kanab Valley and many other localities, the entire 
 
 group is well exposed. 
 
 HENRY'S FORK GROUP. 
 
 This group can be well studied at the typical locality which is on the 
 
LOCALITIES WHERE THE GROUPS CAN BE STUDIED. 51 
 
 south side of Henry's Fork, commencing about two miles above its mouth 
 and extending for many miles to the westward. These beds stand on edge 
 and are well exposed. Their junction with the black shales can be plainly 
 seen and the base of the group is the second conglomerate below the teliost 
 shales; the teliost shales themselves constitute a conspicuous datum point 
 from which to study the stratigraphy of this district. Many sections can be 
 obtained on either side of the Uinta Mountains. Perhaps no better place 
 can be found than on Ashley's Creek, where the group stands in a hogback 
 near Dodd's Ranch. Many other localities could be mentioned on the 
 Price, Escalante, Dirty Devil, Paria and Kanab Rivers. 
 
 FLAMING GORGE GROUP. 
 
 This group can be well studied at the typical locality, viz, in the vicin- 
 ity of Flaming Gorge. Commencing at the conglomerate above mentioned 
 as forming the base of the Henry's Fork Group, you pass southward over 
 the upturned edges of the beds, crossing the bad-land sandstones, then the 
 Mid-group Limestones, then the bad-land indurated sandstones, until the 
 White Cliff Limestone is reached. The massive, cross-bedded sandstones 
 beneath, is a very conspicuous feature of the landscape, and forms the sum- 
 mit of the next group. 
 
 In mentioning the typical and other localities of the foregoing groups 
 I have not given detailed sections, as in a following chapter, on the descrip- 
 tive geology of the Uinta Mountains and adjacent country, it will be neces- 
 sary to describe more minutely the stratigraphy of all these groups. These 
 typical localities excepting that of the Sulphur Creek Group all fall within 
 the area that is to be described. The typical localities of the remaining or 
 lower groups are without the region described in this volume, and hence I 
 shall give sections of the groups as they occur at the typical localities. 
 
 WHITE CLIFF GROUP. 
 
 The locality selected as representing the typical series of this group is 
 in Southern Utah. Here a long irregular escarpment or line of cliffs is seen 
 facing southward, from which the geologist may overlook two other sub- 
 parallel lines of cliffs and see in the distance the walls of the Grand Canon 
 
52 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 of the Colorado. The Paria, Kanab and Rio Virgen, with their many tribu- 
 taries that head in the Pink Cliffs above and to the north, have cut many 
 canons and canon valleys through these escarpments, and here the structural 
 geology and stratigraphy are plainly revealed; not only of the White Cliff 
 Group but also of the Vermilion Cliff and Shinarump Groups. The sec- 
 tion which I shall give of these three groups was made along the course 
 of the Kanab in the winter of 1871. 
 
 The escarpment known as the White Cliffs presents to the mid-day sun 
 a bold wall of pure white or golden sandstone reflecting its rays with a shim- 
 mering, brilliant light. At such a time the traveler toiling over the and sand- 
 dunes below, sees before him to the east or west a long stretch of pink and 
 vermilion hills hills of shifting sands, with no promise of spring or brook 
 at which his thirst may be quenched; the precipice of the Vermilion Cliffs 
 to the south, and the White Cliffs a wall of fire to the north. A more con- 
 spicuous or well denned topographic feature could not well be imagined. 
 
 On top of the wall and usually a little back from the edge the lime- 
 stones which form the base of the Flaming Gorge Group is seen. This lime- 
 stone has been traced from point to point along the intermediate country 
 for the entire distance from Flaming Gorge to the White Cliffs. 
 
 The following is a section of the White Cliff, Vermilion Cliff, and Shina- 
 rump Groups' from the base of these limestones to the summit of the Upper 
 Aubrey Group. 
 
LOCALITIES WHERE THE GROUPS CAN BE STUDIED. 53 
 
 FIG. 9. SECTION OF WHITE CLIFF, VERMILION CLIFF, 
 AND SHINARUMP GROUPS. 
 
 1,000 
 
 2,000 
 
 3,000 
 
 4,000 
 
 WHITE CLIFF GROUP. 
 
 No. 1, 600 feet. Light gray or white sandstone ; massive ; cross-bedded. 
 
 No. 2, 300 feet. Bright pink and vermilion sandstone ; cross-bedded. 
 
 No. 3, 200 feet. Gray, red, and brown sandstone ; cross-bedded ; of many cojors ; tl 
 
 colors appearing in bands with oblique lamination, giving the rocks a beautifully v 
 
 riegated appearance. 
 
 the 
 a- 
 
 VERMILION CLIFF GROUP. 
 
 No. 4, 50 foot. Red friable sandstone. 
 
 No. 5, 180 foot. Massive sandstone ; cross-bedded ; with a few irregular beds of lime- 
 
 stoiie not persistent horizontally; stained rod on exposed surfaces. 
 No. C, 320 feet. Red sandstone ; thickly bedded. 
 No. 7, 2 feet. Calciferous sandstone. 
 No. 8, 100 feet. Orange or /vermilion sandstone. 
 No. 9, 5 feet. Light gray sandstones. 
 No. 10, 400 feet. Orange sandstones ; rather massively bedded. 
 
 SHINARUMP GROUP. 
 
 No. 11, 800 feet. Bad-land sandstones, rapidly disintegrating ; argillaceous ; weather 
 
 ing in variegated hills. 
 No. 12, 80 feet. Conglomerate. 
 
 No. 13, 193 feet. Red, bail-land sandstone ; very friable, with much gypsum. 
 No. 14, 100 feet. Greenish gray bad-land sandstone, with much- gypsum, and rapidly 
 
 disintegrating. 
 
 No. 15, 8 feet. Compact gray sandstone. 
 
 No. 16, 3! foot. lied sandstones and arenaceous shales ; gypsum in seams and joints. 
 No. 17, 250 feet. Red and brown sandstone ; rather thinly bedded, with many ripple 
 
 marks. 
 No. 18, 50 foot. Conglomerate with angular and rounded fragments of limestone in a 
 
 matrix of calciferous sand. 
 
 The sandstones of this group are well seen in the vicinity of Flaming 
 Gorge on the south side of the Green River; again between Dry Lake and 
 Vermilion Creek north of Po Canon, and in a narrow zone on the south side 
 of the Uinta Mountains, and in many other places on the tributaries of the 
 Green and Colorado Rivers; and everywhere the lithologic characteristics 
 are more or less persistent. The cross-bedded sandstones usually form a 
 conspicuous landmark. 
 
54 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 VERMILION CLIFF GROUP. 
 
 The wagon road from Toquerville to Paria, a little town on the Paria 
 River, soon after climbing 1 the Hurricane Ledge reaches the foot of the 
 Vermilion Cliffs, and continues at this geological horizon until it commences 
 to descend into the valley of the Paria. For seventy-five miles the road 
 lies under this great ledge, whose salient buttes, deep alcoves, terraced and 
 buttressed walls, towering pinnacles, all brightly colored in orange, vermilion 
 and purple, and dotted here and there with straggling cedars and nut pines, 
 constitute a grand panorama to the passing traveler. 
 
 Flaming Gorge on the Green River is cut through beds of this group 
 and receives its name from the bright colors of vermilion sandstone ; Laby- 
 rinth Cailon is cut through vermilion sandstone ; Glen Canon for the greater 
 part of its course also, and fine exposures are seen along the Colorado 
 Chiquito. 
 
 SHINARUMP GROUP. 
 
 South of the Vermilion Cliffs a low ledge or escarpment is seen capped 
 with conglomerate. This is the Shinarump Conglomerate. 
 
 The variegated beds above and below the conglomerate are seen in 
 many places on either flank of the Uinta Mountains, and from time to time 
 this horizon is brought up by faults or flexures in all the stretch of country 
 which intervenes between the Shinarump Cliffs and the Uinta Mountains. 
 
 UPPER AUBREY GROUP. 
 
 Mr. Gilbert, as geologist of the Wheeler expedition, described certain 
 groups of limestones, sandstones and shales as the Aubrey Group. Previous 
 to his publication I had in manuscript divided these beds into two groups 
 and given them names ; but in carrying out my determination to use the 
 names of groups which had been adopted by others so far as such names 
 were available, I have decided to call the two groups into which I wish to 
 divide the Aubrey beds of Mr. Gilbert, the Upper and Lower Aubrey 
 Groups. 
 
 The beds of the Upper Aubrey are exposed for thousands of miles 
 along the Grand Canon of the Colorado and its lateral canons, everywhere 
 
LOCALITIES WHEEE THE GROUPS CAN BE STUDIED. 55 
 
 forming the summit of the walls of these gorges. They are also well exposed 
 along Marble Canon ; and Cataract Canon at the junction of the Grand and 
 Green furnishes another good section. Good sections are obtained at Horse- 
 shoe Canon, the Canon of Lodore, Whirlpool Canon, and Split Mountain 
 Canon in the Uinta Mountains. Its junction with the Shinarump Group 
 above, in all these places can be plainly seen, and in like manner its junction 
 with the Lower Aubrey Group is apparent. To the southward in the Grand 
 Canon country these beds are a series of cherty limestones. At the junction 
 of the Grand and Green they are a series of sandstones with intercolated 
 cherty limestones, with a homogeneous sandstone at the summit 150 feet 
 in thickness. In the Uinta Mountains we have a homogeneous gray Sand- 
 stone which we call the Yampa Sandstone, from 1,000 to 1,200 feet in thick- 
 ness, capped by a bed which is believed to be the equivalent of the one 
 mentioned as found at the summit of the series at the junction of the Grand 
 and Green, and varies from 150 to 200 feet in thickness. On the south side 
 of the Uinta Mountains it is an indurated, calciferous sandstone, but on the 
 north side of the mountains it is a cherty limestone, and on both flanks of 
 these mountains it is characterized by a species of bellerophon. Here we 
 have called it the Bellerophon Limestone. 
 
 LOWER AUBREY GROUP. 
 
 The Lower Aubrey Group is seen underlying the Upper Aubrey at 
 all the localities mentioned for that group. In the Grand Cation it is a 
 conspicuous group, its relations to the Upper Aubrey and the Red Wall 
 Groups being well marked. At the junction of the Grand and Green the 
 lines of demarkation cannot be so closely drawn but they appear again 
 very clearly in the Uinta Mountains. 
 
 RED WALL GROUP. 
 
 The Red Wall Group is the most conspicuous feature of the Grand 
 Canon of the Colorado and its tributary gorges. It often stands in a vertical 
 wall 2,000 feet high or more, and is everywhere carved into a series of 
 grand amphitheaters, which I have elsewhere tried to describe. There are 
 two well defined members in the Grand Canon country ; the upper one 
 
5(5 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 thousand feet is a massive, homogeneous, saccharoid limestone ; the lower 
 one thousand feet is composed chiefly of thin beds of indurated limestones 
 of very irregular stratification surfaces. These beds are somewhat argilla- 
 ceous. The group is not well exposed in Cataract Caiion, as the river has not 
 yet cut through the beds at that point, and some very curious displacements 
 along the river serve to obscure the characteristics of the beds that are 
 exposed. In the Uinta Mountains the two members seen in the Grand 
 Canon are represented by two massive, indurated limestones, often con- 
 taining chert and separated by arenaceous shales. 
 
 TON TO GKOUP. 
 
 I have elsewhere called these the rust colored beds, but Mr. Gilbert 
 has called them the Tonto Group, and I accept his name. These beds are 
 seen to overlie unconformably the beds of the Grand Canon Group and of 
 the Grand Caiion Schists. They are seen well exposed along or near the 
 bottom of the Grand Canon, where the river makes its double detour 
 around tlie Kaibab Plateau, and again farther westward, where the river 
 makes another detour around the Shi-wits Plateau. 
 
 A group of sandstones and arenaceous shales is found below the Red 
 Wall horizon in Lodore and Whirlpool Canons, where- the Green River 
 cuts through the Uinta Mountains. In the beds of this latter place I have 
 discovered Carboniferous fossils, and suppose them to be of the same age as 
 the Tonto Group ; yet, as Mr. Gilbert has considered the Tonto beds to be 
 of Silurian Age, I have called the latter Lodore Group provisionally. 
 From geological considerations, I am inclined to consider the Tonto Group 
 as forming the base of the Carboniferous series. The supposed Cnmami 
 and metamorphosed corals discovered by Mr. Gilbert are not deemed by me 
 to furnish sufficient evidence of their greater age. Their geological rela- 
 tions being apparently the same as the Lodore series, I am inclined to 
 refer them to the same horizon ; the latter have been demonstrated to 
 be Carboniferous. My opinion is strengthened by the fact that I find in 
 the Grand Canon 10,000 feet of sandstones, shales and limestones, under- 
 lying them unconformably, and hence separated by a long period of ero- 
 sion, and 'at the base of this latter series I have found Silurian fossils. I 
 
TTY 
 
TJinta Mountains. 
 
 FIG. 10. Comparative sections of Carboniferous strata. 
 Cataract Canon. 
 
 Grand Canon. 
 
 - 1000 
 
 _ 2000 
 
 3000 
 
 - 4000 
 
UINTA MOUNTAIN SECTION. 57 
 
 consider the Tonto, Red Wall, Lower Aubrey, and Upper Aubrey Groups 
 to represent the Carboniferous time from base to summit. 
 
 In Figure 10 I give a Uinta Mountain, Cataract Canon, and Grand 
 Caf5 on section of these groups, side by side, for comparison. The Uinta 
 Mountain and Cataract Canon Sections were made by Mr. J. F. Steward. 
 
 UINTA MOUNTAIN SECTION. 
 
 By J. F. STEWARD. 
 UPPER AUBREY GROUP. 
 
 No. 1, 175 feet. Calciferous sandstone, containing Bdlerophon, con- 
 
 chifers, &c. 
 
 No. 2, 1,400 feet. Massive buff sandstone. 
 
 LOWER AUBREY GROUP. 
 
 No. 3, 90 feet. Limestone, mottled dark, drab, and buff; very hard; 
 cup corals and Product us abundant. 
 
 No. 4, 200 feet. Buff limestone, very fossiliferous ; Spirtfer, Atliyris, &c., 
 abundant. 
 
 No. 5, 75 feet. Heavy bedded, bluish-drab limestone ; lower portion 
 buff colored. This bed is filled with nodules of chert, (red, pink and purple 
 chalcedony;) also abounds in remains of cyathophylloid corals, Spinfer, 
 and Productus, all siliceous. 
 
 No. 6, 90 feet. Thinly bedded rocks, often shaly ; texture variable ; 
 composition calcareous, arenaceous, and argillaceous. 
 
 No. 7, 180 feet. Compact buff sandstone ; very-hard. 
 
 No. 8, 20 feet. Dark bluish-drab limestone ; very hard. 
 
 No. 9, 150 feet, Light pinkish-buff, fine grained sandstone. 
 
 RED WALL GROUP. 
 
 No. 10, 750 feet. Heavy bedded limestone, of pinkish-drab color, be- 
 coming arenaceous toward the top, and of a bright red color. , 
 
 No. 11, 150 feet. Reddish, compact, and shaly sandstones. 
 
 No. 12, 185 feet, Pinkish, purple, brown, and bluish limestone, colored 
 pink on the surface by oxide of iron from the overlying sandstone. 
 
58 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 No. 13, 750 feet. Very compact, bluish-drab limestone, containing 
 numerous seams of chalcedony. 
 
 No. 14, 150 feet. Purplish and drab argillaceous shales. 
 
 No. 15, 225 feet. Buff limestone, not well exposed. 
 
 No. 16, 300 feet. Limestone and sandstone, thinly bedded ; only upper 
 members exposed. 
 
 LODOKK GKOUP. 
 
 No. 17. 465 feet. Thinly bedded sandstones, lying unconformably on 
 
 the Uinta Group. 
 
 CATARACT CANON SECTION. 
 
 By J. F. STEWARD. 
 UPPEE AUBREY GEOUP. 
 
 No. 1, 150 feet. Friable, buff colored, homogeneous sandstone. 
 
 No. 2, 450 feet. Red sandstone, thickly and thinly bedded. 
 
 No. 3, 105 feet. Fine grained sandstone, ending in a foot of very 
 brown, shaly sandstone. 
 
 No. 4, 95 feet. Brownish-buff sandstone. 
 
 No. 5, 25 feet. Compact, bluish-drab limestone, containing Productus 
 nebrascensiSj Aihyris subtilita, crinoidal stems, nodules of red chert, &c. 
 
 No. 6,210 feet. Mostly massively bedded, coarse sandstone, almost a 
 conglomerate at top, but gradually becoming fine textured ; dark red and 
 shaly at base ; Belleroplion. 
 
 No. 7, 4 feet. Hard, compact, dark blue limestone. 
 
 No. 8, 6 feet. Fine buff sandstone. 
 
 No. 9, 50 feet. Blue limestone, divided into three parts by arenaceous 
 members. 
 
 No. 10, 92 feet. Drab sandstone, very coarse at top, but becoming fine 
 at base. 
 
 LOWEE AUBEEY GEOUP. 
 
 No. 11, 721 feet. Sandstone and limestone in alternation. 
 , 70 feet. Drab, compact limestone, containing in great numbers Allo- 
 risma, Myalina, &c. ; also a large Pleurotomaria. 
 
 b, 12 feet. Fine grained, light gray sandstone, very friable. 
 
 c, 3 feet. Compact limestone, same as a. 
 
CATARACT CAtfON 8ECTION. 59 
 
 d, 50 feet. Fine grained, incoherent, ochre-brown sandstone. 
 
 e, 43 feet. Light colored, arenaceous shale. 
 
 f t 10 feet. Dark gray limestone, very compact and hard, containing 
 crinoids. 
 
 <7, 40 feet. Soft, friable, drab sandstone. 
 
 hj 30 feet. Compact, drab, fossiliferous limestone. 
 
 ij 75 feet. Fine grained, heavily bedded, friable, lavender-buff sand- 
 stone. 
 
 .;, 12 feet. Drab, argillaceous, arenaceous shales, containing vermiform 
 concretions of chalcedony. 
 
 &, 18 feet. Friable limestone, largely composed of crinoid stems, &c. 
 
 I, 10 feet. Buff and lavender, fine grained, incoherent sandstone. 
 
 m, 15 feet. Very low, compact, drab limestone, heavily bedded, and 
 filled with fragmentary fossils. 
 
 n, 12 feet, Marly, buff, crinoidal sandstone ; Productus, Spwifer, &c. 
 
 o, 42 feet. Fine grained sandstone, buff to drab at top, brown at base. 
 
 p, 6 feet. Dark gray limestone, containing Productus, Spirifer, Chae- 
 tetes, &c. 
 
 q, 40 feet. Fine, light brown sandstone, massively bedded, changing 
 to shale at base. 
 
 r, 25 feet. Very hard, compact, blue limestone. 
 
 5, 4 feet. Blue, argillaceous shales, containing a branching Cfatetes, 
 Productus, &c. 
 
 t, 2 feet. Hard, buff limestone. 
 
 % 60 feet. Friable, fine grained, buff sandstone. 
 
 v, 22 feet. Hard, bluish drab limestone, with concretions of red chal- 
 cedony. 
 
 w, 75 feet. Light buff sandstone, very fine and incoherent ; in part 
 calciferous. 
 
 aj, 50 feet Hard, concretionary limestone, with nodules and thin seams 
 of chalcedony. 
 
 y, 15 feet. Fine buff sandstone. 
 
 #, 50 feet. Very hard, dark drab limestone, containing siliceous con- 
 cretions. 
 
60 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 RED WALL GROUP. 
 
 No. 12. Thickness not determined. Buffish-lavender, friable, fine 
 grained sandstone ; base not seen. 
 
 GRAND CANON SECTION. 
 UPPER AUBREY GROUP. 
 
 No. 1, 145 feet. Limestone and sandstone, not very thickly bedded. 
 
 No. 2, 220 feet. Massive limestone, brecciated and cherty, and.weather- 
 ing in columnar forms. 
 
 No. 3, 170 feet. Gypsum and gypsiferous sandstone, irregularly bedded, 
 contorted and broken, stained brown in patches. 
 
 No. 4, 240 feet. Massive limestone. 
 
 LOWER AUBREY GROUP. 
 
 No. 5. Bright red sandstones, thinly and thickly bedded, very red, 
 weathering in long slopes. 
 
 No. 6, 600 feet. Red and buff sandstones, heavily bedded, exhibiting 
 composite structure, (cross bedding,) with irregular and inconstant beds of 
 limestone. 
 
 RED WALL GROUP. 
 
 No. 7. Limestones and calciferous sandstones ; heavily bedded ; gray 
 and brown ; much chert in limestone ; chert red and vitreous ; sandstone 
 friable. 
 
 No. 8, 800 feet. Massive granular limestone ; in some places cherty ; 
 sometimes running horizontally into thinly bedded rocks. 
 
 No 9, a, 10 feet. Friable, greenish sandstones, b, 6 feet. Purple sand- 
 stones, thinning out in places; has the appearance of having been eroded. 
 
 No. 10, 300 feet. Thinly bedded limestone, with layers and nodules of 
 chert. 
 
 No. 11, 50 feet. Sandstones; gray and buff; sometimes mottled; 
 probably calciferous. 
 
 No. 12, 100 feet. Heavily bedded limestone, with calciferous sand- 
 stones at summit. 
 
GRAND CANON SECTION. 61 
 
 No. 1 3, 400 feet. Thinly bedded, bluish limestone, with intercalated, 
 thinly bedded sandstones and clay shales below. The limestones are con- 
 cretionary and brecciated, and have many cavities filled with calcspar. 
 
 No. 14, 100 feet. Greenish, micaceous shales, with beds of gray and 
 brown sandstone, containing iron concretions. 
 
 TONTO GEOUP. 
 
 No. 15, 75 feet. Limestones; a good marble; often mottled; some- 
 times containing concretions of chert. 
 
 No. 1G, GOO feet. Rust colored sandstones ; thinly bedded ; indurated; 
 reenish above. 
 
 No. 17, 100 feet. Brown sandstone. 
 
 
 * * * 
 
 UINTA GEOUP. 
 
 The Uinta Mountains are chiefly composed of Uinta Sandstone. The 
 western end of this range where it abuts against the Wasatch Ranor-e, I 
 
 o O O / 
 
 have not carefully studied; but to the eastward the broad, massive range is 
 a grand sandstone structure. Other groups are turned up on their flanks, 
 and in Red Creek Caiion a lower group is seen. On the southeast margin 
 of the range a line of peaks may be seen extending across the Canon of 
 Lodore, composed of groups of Red Wall Limestone. 
 
 In the many deep canons and gulches by which the range is cleft, in 
 the many amphitheaters that are found along the crest of the range, and in 
 the mural faces of its lofty peaks, everywhere the sandstones are made bare 
 to the eye of the geologist; but the best sections can be made along the 
 canons. In a subsequent chapter some of these sections will be given. 
 
 GEAND CANON GEOUP. 
 
 This group is exposed in the great southern bends of the Grand Canon, 
 where the Colorado River passes the end of the Kaibab Plateau. The best 
 
 * 
 
 exposure can be seen about ten miles below the mouth of the Little Colo- 
 rado. Many of the lateral streams coming in from the west and north cut 
 through this group and afford fine exposures. The best one probably is in 
 
62 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 Kwa-gunt Valley. Some of the members are again exposed at the bottom 
 of the Grand Canon, where it passes the Shi-wits Plateau. 
 
 Lower Silurian fossils have been found at the base of this group. 
 
 EED CEEEK GEOUP. 
 
 The Red Creek Quartzite, with its intercolated beds of hornblendic, 
 micaceous and chloritic schists, is well seen in Red Creek Canon. Other ex- 
 posures can be seen at the head of Willow Creek, a little stream that 
 comes down from the O-wi-yu-kuts Plateau, and empties into the Green 
 River midway in Brown's Park. 
 
 GEAND CANON SCHISTS. 
 
 This group is revealed in the depths of the Grand Canon in all its 
 great southern bends. 
 
 EPOCHS SEPARATING THE GROUPS. 
 
 BISHOP MOUNTAIN CONGLOMEEATE. 
 
 The Bishop Mountain Conglomerate is found at different places to lie 
 unconformably upon every group of the table which is represented in the 
 Uinta Mountains and adjacent country. Its plane of demarkation repre- 
 sents a cessation of the movements of displacement in the region over which 
 it is found, and that the same region was planed down to a base level of ero- 
 sion, which base level was continued during the accumulation of these beds, 
 for it is believed to be a subaerial conglomerate; but should further evidence 
 prove it to be a subaqueous accumulation the plane of separation would then 
 represent an epoch of change from a period of erosion to a period of depo- 
 sition. This point will be more fully discussed hereafter. 
 
 BEOWN'S PAEK GEOUP. 
 
 This group in Brown's Park is seen to lie unconformably on the Uinta 
 Sandstone, and all the other Paleozoic, Mesozoic and early Cenozoic groups; 
 the plane of demarkation, therefore, represents an epoch of change from a 
 dry land to a submerged condition. The area over which it was deposited 
 within the region of my study is of small extent, but the beds are known 
 
EPOCHS SEPARATING THE GROUPS. 63 
 
 to continue farther eastward beyond the belt examined; and it may be 
 found as examination is carried farther in that direction to be conformable 
 with the next lower. 
 
 BRIDGER GROUP. 
 
 The plane of demarkation between this group and the next in order is 
 not always well defined. The change from the green sands or bad-land 
 rocks to the indurated sandstones and limestones of the Upper Green River 
 is transitional; yet the epoch of change is important, for the Upper Green 
 River attenuates both to the east and west, and in the latter direction it 
 entirely disappears, so that the Bridger beds lie with an apparent conformity, 
 but actual unconformity, on the beds of the Lower Green River. This is 
 seen in the vicinity of Carter Station. 
 
 UPPER GREEN RIVER GROUP, 
 
 These beds are interpolated between the Bridger and Lower Green 
 River, as described above, only in a portion of the country where the latter 
 two occur. The Tower Sandstone which forms the base of the Upper 
 Green River Group is laid down unconformably on the Lower Green 
 River, the unconformity being represented by gentle valleys of erosion; 
 and there seems to have been a period of erosion or dry land conditions 
 separating the Tower Sandstone from the Plant Beds of the Upper Green 
 River also, and during this dry land period the sands of the Tower Sand- 
 stone were eroded by rains and drifted by winds. After the deposition of 
 the sands, the bottom of this great Green River lake was left bare for a 
 time and the sands drifted in dunes. 
 
 LOWER GREEN RIVER GROUP. 
 
 The Lower Green River beds represent a period when minutely lami- 
 nated bituminous shales and more massive limestones were deposited, the 
 limestones prevailing as you descend in the series. These beds are all 
 fresh water and are separated from those below by an abrupt plane of 
 stratification which marks a change in the character of the sediments. 
 The lower beds are soft, friable, and highly colored bad-land sandstones. 
 But this plane of separation means something more. The conditions which 
 
64 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 prevailed during the deposition of the lower sandstones abruptly changed, 
 leaving a part of the ancient lake dry and a part submerged, and in this 
 submerged area the limestones and shales were deposited. 
 
 BITTER CREEK GROUP. 
 
 The Bitter Creek beds are chiefly bad-land sandstones. The area of 
 lacustrine deposition had its greatest expansion during this time. The 
 plane of demarkation separating it from the next group in order is one of 
 great importance. When the beds of the underlying group had been laid 
 down, and before these beds were formed, that movement began which, 
 carried on through Cenozoic time, has given us the great Uinta upheaval. 
 There seems to have been a widely spread dry land condition separating 
 them, for on the flanks of the mountains the lower Bitter Creek beds rest 
 unconformably on the next group, and this unconformity is by erosion 
 and also by angle of dip. This is seen in several places. But the move- 
 ment in upheaval in the Uinta Mountains was oscillatory, and we often 
 find the upper members of the Bitter Creek series overlapping the older 
 members, and in extreme cases all of the groups of Mesozoic Age also. The 
 unconformity between the two groups away from the mountains is simply 
 represented by erosion. The hard, gray sandstone, which is the upper 
 member of the Point of Rocks Group, is often seen to have been eroded 
 into gentle or more abrupt valleys, and the shales of the Bitter Creek Group 
 were carried into and filled these valleys. 
 
 These facts are exhibited in very many places on either flank of the 
 Uinta Mountains, and on either flank of the Aspen Mountain fold, or 
 that fold the axis of which is seen in the Salt Wells Basin ; yet there are 
 many points where the conditions of recent erosion are such that the junc- 
 tion of the two groups are more or less masked, and where the uncon- 
 formity is less apparent. 
 
 But this epoch of change has a more important significance. The 
 group below I have classed with the Mesozoic, the group above with the 
 Cenozoic, and the change was from marine to lacustrine conditions. But 
 this change was not abrupt ; brackish water fossils are found in the lower 
 group associated with marine forms, and with these a few species of 
 
EPOCHS SEPARATING THE GROUPS. 05 
 
 geophila ; and brackish water fossils, in perhaps a very few instances of the 
 same species with those below, are associated with fresh water fossils ; hence 
 the change from marine to fresh water conditions seems not to have been 
 abrupt. 
 
 It will be noted that the epochs of change which separate the fresh 
 water Cenozoic groups all represent a change in character of the sediments, 
 and also represent more or less abrupt contraction of the expanse of fresh 
 water. This was very great during the Bitter Creek period ; somewhat 
 less during the Lower. Green River; somewhat less during the Upper; 
 perhaps about, the same, but less in some directions and greater in others, 
 during the Bridger ; and when we reach that point of time represented by 
 the Brown's Park beds the area was quite small. 
 
 Those beds to which the name Wasatch Group has been given, and 
 which are found on the eastern slope of the Wasatch Mountains, and 
 stretching out to the eastward until they run under Lower Green River 
 beds, are the western extension of the Bitter Creek beds, and hence the 
 name Wasatch Group should be dropped. The conglomerate at the 
 bottom of what was called the Wasatch Group is represented by the con- 
 glomerates of the Bitter Creek Group on bo'Ji flanks of the Uinta Mount- 
 
 6 
 
 ains. 
 
 The beds called the Washiki Group are the upper part of the Bitter 
 Creek series. I have been unable to carry any line of demarkation 
 between these beds over such an extent of country as would warrant their 
 separation from the Bitter Creek series, yet this may be done, and in such 
 a case the name of Washiki Group should be retained. In the region near 
 Washiki Station, where they were first seen by Dr. Hayden, they are 
 exceedingly conspicuous by reason of their brilliant colors. Professor 
 Cope, who saw them a little farther to the southwest, thus appropriately 
 describes them: "Several miles to the south we reach another bench whose 
 bluffy face rises four or five hundred feet in buttress-like masses, interrupted 
 at regular intervals by narrow terraces. This line is distinguished by its 
 brilliantly colored strata, extending in horizontal bands along the escarp- 
 ment. They are brilliant cherry-red, white, true purple with a bloom- 
 si lade yellow and pea-green, forming one of the most beautiful displays I 
 5 P G 
 
66 SEDIMENTAEY GROUPS OF THE PLATEAU PROVINCE. 
 
 ever beheld. The lower portions are of bright red, which color predom- 
 inates toward the west, where the bluffs descend to a lower elevation. I 
 found on them the remains of a turtle (Emys eutlmethus Cope), and. some 
 borings of a worm in a hard layer. On top of these are clay and slate- 
 rocks of a muddy-yellow color, with their various ledges rising to perhaps 
 five hundred feet" (vide United States Geological and Geographical Survey 
 of Colorado, page 437). 
 
 These latter beds are Lower Green River limestones. 
 
 In the same article, and immediately preceding this quotation, Pro- 
 fessor Cope says : " At a short distance to the southward another line of 
 white bluffs extends across the line of travel. This is not more elevated 
 than the preceding one ; I only found remains of tortoises in it," 
 
 On either flank of the Aspen Mountain fold this group of beds weath- 
 ering white is seen, and I have several times at first confounded them with 
 the Lower Green River, but the shales of these beds are carbonaceous, and 
 often contain more or less lignitic coal ; those of the Lower Green River 
 are bituminous and yield oil. The limestones of the former are aggrega- 
 tions of shells or shell-marls. 
 
 THE CRETACEOUS GROUPS. 
 
 Planes of demarkation in the Cretaceous groups are not easily drawn. 
 The three great, massive sandstones of the Point of Rocks Group are in 
 many places broken into thinner beds, and then it becomes impossible, with 
 our present knowledge at least, to say to which of these members particular 
 beds may belong. The group below usually is very thinly bedded ; some- 
 times, however, these beds are thicker and more indurated, and when this 
 is the case and the Point of Rocks Group is broken up it is difficult to draw 
 a line between the two groups. The same difficulty arises in separating 
 the yellow arenaceous shales and the black argillaceous shales. Wherever 
 the two groups are exposed side by side, above are seen thinly bedded sand- 
 stones and shales and below are black, minutely laminated shales, but it is 
 very rare indeed that an exact line can be drawn. In the southern portion 
 of the province the Salt Wells beds are massive, and there the separation is 
 more easily made. The black shales of the Sulphur Creek Group are 
 
EPOCHS SEPARATING THE GROUPS. 67 
 
 everywhere seen to rest upon a somewhat massive sandstone which is under- 
 laid by bad-land sandstones, shales, conglomerates, &c., with a somewhat 
 massive indurated sandstone at the bottom. There seems to be a very 
 decided change in the paleontology of these groups from base to summit, 
 but the fossils, so far as now known, do not afford definite lines of demar- 
 kation. 
 
 The relation of these groups to those established by Professors Meek 
 and Hayden on the Upper Missouri is not well determined. I have care- 
 fully tried to use their system of grouping and have failed. A very 
 different lithologic series is observed, as must be apparent from a comparison 
 of the two sections. Most of the fossils are of different species, and the 
 few that can be referred to the species of Professors Meek and Hayden in 
 that region present contradictory evidence. Those fossils that may be 
 referred to "No. 2" are found above fossils which may be referred to " Nos. 
 3 and 4," and as we are tracing these bejds over broad areas, and from time 
 to time collecting new fossils, the stratigraphic relations of which should be 
 given with their description, it seemed necessary that some grouping 
 should be adopted, and I have given the best I could under the circum- 
 stances. Perhaps after -the paleontology is more thoroughly studied the 
 Upper Missouri groupings can be adopted here, but my present opinion is 
 that all such attempts will prove futile. These opinions are based chiefly 
 upon geological reasons, viz : All the evidence that has been published by 
 Dr. Hayden and members of his corps concerning the Park Province, and 
 all my own observations in that region, lead me to the conclusion that a long 
 chain of islands stretched in a northerly and southerly direction through 
 that region of country, separating the Cretaceous sea of the Plateau Prov- 
 ince from the Cretaceous sea of the Upper Missouri ; probably not forming 
 a continuous wall between fhe waters of the two, but separating them in 
 such a manner that very different physical conditions prevailed. It is mani- 
 fest that the Cretaceous sea of the Plateau Province was fed chiefly with 
 the sediments of the Basin Province, for all the- Cretaceous sediments rap- 
 idly attenuate from that old shore line eastward, and many conglomerates 
 and coarse sandstones of Cretaceous Age found there, are steadily replaced 
 by finer materials in an easterly direction. It is much more probable that 
 
68 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 the Cretaceous sea of the Basin Province was continuous with that of Texas. 
 The geological evidence seems to indicate this ; the evidence derived from 
 the fossils I leave for others to discuss. 
 
 FLAMING GORGE GROUP. 
 
 The epoch separating the Flaming Gorge Group from the Henry's Fork 
 Group above was one which produced a change from bad-land sandstones 
 to a conglomerate. The beds which overlie the conglomerate contain marine 
 fossils, but all the fossils which we have obtained from the upper portion of 
 the Flaming Gorge Group are of lacustrine habitat. The Mid-Group Lime- 
 stone contains marine species, and this is true of the limestone at the base, 
 i. e., the White Cliff Limestone. The White Cliff period ended with the 
 deposition of a massive cross-bedded sandstone; the Flaming Gorge period 
 commenced with a deposition of limestone; thus we have an important 
 epoch of change separating the two groups and this is widely spread, for 
 it has been seen wherever the junction of the two groups has been studied. 
 
 WHITE CLIFF, VERMILION CLIFF, AND SHINARUMP GROUPS. 
 
 These groups can be separated, only in a very general way. The 
 upper group is characterized near the summit by a very persistent, massive, 
 cross-bedded sandstone. The Vermilion Cliff Group is also a massive sand- 
 stone, and the base of the White Cliff Group is sometimes composed of 
 massive sandstones, sometimes of thinly bedded sandstones, and often these 
 beds are highly gypsiferous, in which case they disintegrate so rapidly that 
 the bedding cannot be studied. The group has yielded no fossils. 
 
 The Vermilion Cliff Group as a great mass is easily recognized every- 
 where, but just where we should draw the line above is rarely plain. Often 
 the massive sandstones of this bed are separated by very irregular and 
 inconstant layers or aggregations of hard calciferous sandstones. These 
 layers have yielded a few imperfectly preserved fossils. 
 
 The summit of the Shinarump Group is a series of gypsiferous sand- 
 stones exceedingly friable. They have often been called marls, and the 
 separation between them and the massive vermilion sandstone is never very 
 distinct. The difficulty is much greater where the gypsum disappears from 
 
EPOCDS SEPARATING THE GROUPS. 69 
 
 the lower beds, as it does in places, where they are also found to be more 
 indurated and more or less massive sandstones. The conglomerate which 
 is found in the middle of the group is persistent over a very large area, and 
 the whole group is characterized throughout the entire province by the 
 occurrence of silicified wood in large quantities Sometimes trunks of trees 
 from fifty to one hundred feet in length are found. The Shinarump Con- 
 glomerate is usually very hard, and weathers in such a manner as to form 
 hog-backs or cliffs, and the softer gypsiferous beds above, when carried 
 away by rains, leave behind fragments of this silicified wood, so that the 
 Shinarump Conglomerate is often covered with great quantities of this ma- 
 terial. Shinarump means literally "Shin-au-av's Rock." Shin-au-av is one 
 of the gods of the Indians of this country, and they believe these tree- 
 trunks to have been his arrows. 
 
 The plane of demarkation between the Shinarump Group and the sum- 
 mit of the Carboniferous is always well marked. Soft, gypsiferous shales are 
 found at the base of the upper group, and cither a pure limestone, a cherty 
 limestone, or a homogeneous sandstone, at the summit of the Carboniferous. 
 In places, however, a conglomerate is found at the base of the Shinarump 
 Group, its coarser fragments being composed of cherty limestone which con- 
 tains Upper Carboniferous fossils. So in some places, at least the epoch of 
 change was a period of erosion. Flaming Gorge Group contains Jurassic 
 fossils from* its summit to its base, but the fossils found in the next three 
 groups below are few and very imperfect; hence we cannof correlate these 
 groups with the general geological succession which has been established 
 throughout the world, but we know they lie between the Jura above and the 
 Carboniferous below. 
 
 THE CARBONIFEROUS GROUPS. 
 
 The grouping* of the Carboniferous beds is fully set forth in the section 
 on page , r >7. The base of the Carboniferous series is not found in Cataract 
 Canon, but in the Uinta Mountains these beds rest unconformably upon 
 the Uinta Group. In the Grand Canon, they rest unconformably upon 
 the Grand Caiion Group and also upon the crystalline schists; hence in 
 both places the plane of demarkation is important, and represents long 
 periods of erosion. 
 
70 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE 
 
 UINTA GKOUP. 
 
 The Uinta Sandstone rests unconformably upon the Red Creek Quartz- 
 ite; ten thousand feet of its upper members are deposited unconformably 
 against that metamorphic group. It is evident, also, that the metamorphism 
 was anterior to the deposition of the Uinta Group, for the beds of the latter, 
 especially near the junction, are chiefly made up of fragments of the former; 
 hence the unconformity is very great. 
 
 The period of erosion separating the sandstones from the Carboniferous 
 beds above was sufficient to carry away at least 3,000 feet of the Uinta 
 Sandstone in some places. How much more was carried away we cannot 
 say. To my mind this suggests that the Uinta Sandstone may be considered 
 Devonian an opinion which I would yield upon the slightest paleontologic 
 evidence to the contrary. 
 
 GRAND CANON GROUP. 
 
 The Grand Canon Group rests uncomformably upon the crystalline 
 schists. The evidence of this is complete, for the lower sandstones and 
 conglomerates first filled the valleys and then buried the hills of schistic 
 rocks, and these conglomerates at the base of the group are composed of 
 materials derived from the metamorphic hills about ; and hence metamor- 
 phism was antecedent to the deposition of the conglomerates. 
 
 The plane of demarkation separating this group from the Tonto Group 
 is very great. At least 10,000 feet of beds were flexed and eroded in such 
 a manner as to leave but fragments in the synclinals. Then followed a 
 period of erosion during which beds of extravasated material were poured 
 .over the fragments, and these igneous beds also were eroded into valleys 
 prior to the deposition of the Tonto Group. 
 
 Fossils have been found at the base of the Grand Canon series, but 
 they are not well preserved and little can be made of them. . Still, on geo- 
 logical evidence, I am of the opinion that these beds should be considered 
 Silurian. 
 
 RED CREEK QUARTZITE AND GRAND CANON SCHISTS. 
 
 These are believed to be Eozoic. 
 
THIS GROUPING TENTATIVE. 71 
 
 The grouping which I have given above should be considered as 
 merely tentative, and will probably need some modification hereafter ; it 
 may possibly need radical changes ; it would be very unsafe with our 
 present knowledge to assume otherwise; I know that* it will need some 
 interpolation in the Cretaceous groups in the southern part of the province. 
 I should have been pleased to have delayed its publication until the entire 
 province had been more thoroughly surveyed, but circumstances render it 
 necessary that I should do something more than make general statements 
 of the methods and results of the work which I have been doing. Congress 
 has appropriated money from year to year for the work on the representa- 
 tion of a few leading scientific men of the country that the work was being 
 done with reasonable skill and economy; but only the few who had time 
 and were willing to examine the work in manuscript at the office could 
 understand what we were doing, and it seemed but reasonable that a 
 demand should be made for the publication of some specific results. Hav- 
 ing concluded to commence the publication before the province was com- 
 pletely surveyed, it was absolutely necessary that some grouping of the 
 geological formations should be used. The map must be colored to show 
 the distribution of geological formations, arid of course names must be given 
 to the formations thus represented on the map, and a nomenclature is 
 necessary for discussion ; hence the publication of the table. But I shall 
 be willing to modify it to any extent as facts are collected which seem to 
 demand such a change, whether such facts are the results of my own labors 
 or those of others. Still I present the table with some degree of confidence. 
 The groups of rocks have been traced over broad areas, and in the district, 
 the geology of which I am to describe in this report, the grouping fully 
 represents the state of my knowledge. On account of the discussions which 
 have arisen concerning the age of certain beds of lignitic coal, the plane of 
 demarkation between the Cenozoic and Mesozoic may subject me to criti- 
 cism ; but, geologically, the plane is important, as it represents a decided 
 physical change, and it certainly harmonizes witli the opinion of paleontolo- 
 gists to a degree that is somewhat surprising. All of the plants described 
 by Professor Lesquereux and collected by himself and others within this 
 province have been referred by him to divisions in the Tertiary, and are 
 
72 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 
 
 found in strata above this physical break, and hence I agree with him in 
 considering them Tertiary. 
 
 In subdividing the Cenozoic or Tertiary, Professor Lesquereux has 
 attempted to draw very fine lines, dividing these beds into Eocene and Mio- 
 cene, and further subdividing each of these two groups into upper, middle, 
 and lower. In doing this he has done violence to the stratigraphy, and 
 sometimes his upper, middle, and lower cross each other; but, in a general 
 way, his Miocene is higher than his Eocene. 
 
 All of the fossils. described by Mr. Meek which have been found above 
 this physical break, he has referred unhesitatingly to Tertiary, and all of the 
 fossils found below the physical break, he has referred, unhesitatingly with 
 some, doubtfully with others, to the Cretaceous. There is a single excep- 
 tion to this in Ostrea Wyomingensis, which is a new species; and I am sure 
 no paleontologist would insist that a new species of ostrea could be used as 
 conclusive evidence in deciding the age of a group of beds. That Mr. Meek 
 did not discover the physical break is not strange, for he did not see it. 
 When he made his exploration in this region he was in ill health, and trav- 
 eled "by rail from station to station, stopping at these places and examining 
 the nocks only in the vicinity of the stations. His health would not permit 
 him to make long excursions in the country on foot, and it was impossible 
 for him to obtain horses. He passed the physical break above mentioned 
 on a railroad car, and his sections at Hallville and Point of Rocks are not 
 connected by several hundred feet, as he states, and as I have since verified 
 by passing over the ground; and the physical break is found in the gap. 
 In like manner, on the opposite side of the Aspen Mountain uplift, he passed 
 
 it in the cars between Point of Rocks and Green River Stations. 
 
 * 
 
 The conclusions reached from a study of the vertebrate paleontology 
 by Professors Leidy, Marsh, and Cope entirely harmonize with this division 
 of the Cenozoic and Mesozoic. There is a single exception to this; Pro- 
 fessor Cope described a dinosaur found near Black Buttes Station as Creta- 
 ceous. I have verified the determination of the stratigraphic horizon by 
 examining the place and finding other dinosaur bones; but this horizon is 
 above the physical break, and the evidence of the dinosaur seems to be con- 
 tradicted by the evidence furnished by many other species described by 
 Professor Cope from about the same horizon. 
 
DIFFERENT SUCCESSION OF COALS. 73 
 
 < 
 
 LIGNITIC COAL. 
 
 An examination of the section will reveal the fact that lignitic coal is 
 found abundant from the base of the Cretaceous through the recognized 
 groups of that division, and in three of the groups of the Tertiary, giving 
 a horizon of 11,500 feet. I know of no lignite bearing group in the Pla- 
 teau Province which may be said to be richer in this product than others, 
 and it would have led to confusion to characterize any group as the "Lig- 
 nite beds." 
 
 While lignitic coal is found in great abundance through a long succes- 
 sion of formations or groups, it is rarely or never the case that any partic- 
 ular bed is persistent over a great area. In the Point of Rocks Group I 
 have at one place found eleven beds, varying from ten inches to four feet in 
 thickness, and three miles away where the exposure was complete so that 
 no mistake could be made except by careless observation I have found 
 each one of these beds represented by carbonaceous shales ; and facts simi- 
 lar to this have been noted in all the other groups. It is frequently the 
 ca.so that, in studying the same group at two places separated by a few 
 miles, a veiy different succession of coals will be observed. It seems that 
 they were formed in small, irregular basins, from time to time, beginning 
 with the Lower Cretaceous and ending high up in the Cenozoic. 
 
 Dr. C. A. White has prepared a catalogue of the species which, so far, 
 have been collected in the Plateau Province, by myself and those assisting 
 me in the work, and tabulated them in groups agreeing with the above 
 scheme. He has also appended to each an additional list of fossils collected 
 by others. The general correlation of the section to established successions 
 elsewhere must at present rest on the evidence furnished by this catalogue. 
 
III. 
 
 INVERTEBRATE PALEONTOLOGY OF THE PLA- 
 TEAU PROVINCE, 
 
 TOGETHER WITH NOTICE OF A FEW SPECIES FROM LOCALITIES BE- 
 YOND ITS LIMITS IN COLORADO, 
 
 BY CHARLES A. WHITE, M. D. ' 
 
 WASHINGTON, D. C., February 1, 187G. 
 
 SIR: I have the honor to present the following preliminary report upon 
 the paleontological collections made by parties under your direction during 
 the years 1868 to 1875, inclusive; more especially upon the invertebrate 
 fossils. 
 
 The collections are large and important, comprising, besides the inver- 
 tebrate fossils noticed and described on following pages, vertebrate remains 
 from strata of the Carboniferous, Jurassic, Cretaceous, and Tertiary periods; 
 and plants from those of the Cretaceous and Tertiary periods. The plants, 
 from strata of the last named period especially, are abundant and interest- 
 ing, comprising as they do representatives of the classes Acrogens, Endo- 
 gens, and Exogens, the latter being greatly in excess of the others. 
 
 Among the vertebrate fossils are the remains of fishes (Selachians, Gan- 
 oids, and Teliosts), reptiles, and mammals. Besides these, a small collection 
 borrowed from Mr. W. Cleburn contains part of the skeleton of a Passerine 
 bird which was discovered by him in the Lower Green River Group, near 
 Green River Station, Wyoming Territory. Some of the other discoveries 
 of vertebrate remains are also worthy of notice here, among which may 
 be mentioned two or three species of teliost fishes at the base of the Creta- 
 ceous series of Wyoming and Utah, and fragments of the skeleton of a very 
 
GENERAL OBSERVATIONS. 75 
 
 large reptile in Jurassic strata of Northwestern Colorado. The collection of 
 Mr. Cleburn also contains two or three species of insects. 
 
 The study of the collections as a whole, reveals many interesting- facts 
 bearing upon the physical conditions of the regions examined, during the 
 deposition of the strata from which they have been collected, some of which 
 are briefly discussed on following pages. Among the more important of 
 these is the identification of the marine genera Oculina^Phorus, Dentalium, 
 Patella, Venus, Mesodesma, c., from the Tertiary strata of Bijou Basin, forty 
 miles east of Denver, Colorado. This indicates the extension of open-sea 
 marine deposits much farther into the interior of the continent during the 
 Tertiary period than has been previously known. 
 
 Upon following pages I present a classified catalogue of all the inver- 
 tebrate species, following which are descriptions of the new species. This 
 catalogue enumerates two hundred and sixty-two species in all, forty-eight 
 of which are new to science, and described herein for the first time. 
 
 Very respectfully yours, 
 
 C. A. WHITE. 
 Professor J. W. POWELL, 
 
 Geologist in charge of the Second Division United States 
 
 Geological and Geographical Survey of the Territories. 
 
 GENERAL OBSERVATIONS. 
 
 The fossils of the collections of which the following pages are occupied 
 in large part by a classified and partially descriptive catalogue, have been 
 obtained from strata of the Carboniferous, Triassic, Jurassic, Cretaceous, and 
 Tertiary periods ; very largely from the immediate vicinity of the Green and 
 Colorado Rivers and from portions of Northern Utah and Southern Wyom- 
 ing. The areas from which they have been collected are very small com- 
 pared with that of the great Plateau Province, the study of the invertebrate 
 paleontology of which the preparation of this report is only a beginning. 
 It is, therefore, too early to draw final conclusions concerning the general 
 lessons which full collections from that great region will be sure to teach 
 us, or to deduce at present, any very satisfactory generalizations; but it 
 may not be unprofitable to mention some of the facts, in their order, that 
 
76 
 
 INVERTEBRATE PALEONTOLOGY. 
 
 [WHITE. 
 
 have been observed while making the collections in the field and also dur- 
 ing- their more critical investigation in the laboratory. Some of these facts 
 have an interesting bearing upon the characteristics of the fossil faunae of the 
 periods which the collections represent, the relation of those faunae to each 
 other, and to both fossil and recent faunae of the whole Plateau Province as 
 well as those of other regions. 
 
 For the purpose of facilitating reference to the groups of strata which 
 have furnished the fossils, the following table is introduced. The classifi- 
 cation of the formations used in this report is, for the geological ages and 
 periods, the same as that of Dana's Manual of Geology (1874,) and for the 
 groups of strata of the Pleateau Province, that of Professor . Powell in his 
 section of the Uinta Mountain region. 
 
 Table of the formations of the Uinta Mountain Region. 
 
 Thickness iu feet. 
 
 Groups. 
 
 Periods. 
 
 1,800. Brown's Park Group 
 
 2,000. Bridger Group 
 
 500. Upper Green River Group. ^ Tertiary [ Cenozoic. 
 
 800. Lower Green River Group . 
 
 3,000. Bitter Creek Group 
 
 1,800. Point of Rocks Group 
 
 1,800. Salt Wells Group . 
 
 fc) AAn a i i n i n ' Cretaceous . . 
 
 2,000. bulpliur Creek Group . . - - 
 
 500. Henry's Fork Group 
 
 1,200. Flaming Gorge Group > Jurassic / Mesozoic. 
 
 > * 
 
 1, 1 00. White Cliff Group 
 
 1,100. Vermilion Cliff Group \. Triassicl 
 
 1,800. Shinarump Group 
 
 1,000. Upper Aubrey Group. 
 
 1,000. Lower Aubrey Group 
 
 r^n ^. i -ITT n /-M r Carbomterous . > Carbomterous. 
 
 2,000. Red Wall Group 
 
 460. Lodore Group 
 
GENERAL OBSERVATIONS. 77 
 
 In the following brief review of the faunal characteristics of the dif- 
 ferent groups represented in the collections it is well to consider how far 
 any peculiarities they present, different from those which characterize their 
 position in time, may have been occasioned by the then and there prevail- 
 ing physical conditions under which the strata were accumulated. Some of 
 those conditions were limited both in extent and duration, but others were 
 of a more general and constant character. Almost all of the fossils of these 
 collections are the remains of mollusks and other aquatic animals. It is a 
 well-known fact that the character of the material composing the bottom 
 upon which such animals live constitutes one of the most important elements 
 in their habitat; that not only species, but even genera and families, are often 
 separated from each other in the same waters by a difference in the character 
 of the material composing the bottom. It is this gradually-accumulating 
 bottom material that has constituted the strata from which we now obtain 
 the fossil remains. The prevailing material of the strata which have furnished 
 the greater part of the fossils of our collections, especially those of Mesozoic 
 and Cenozoic ages, having an aggregate thickness of not far from three and 
 a half miles, is sand. The bottom of the waters, salt, brackish, and fresh, 
 of all the periods of both those ages, was almost constantly, either wholly 
 or in very large part, composed of sand. 
 
 Such a condition as this, continued for so long a time, necessarily pro- 
 duced a marked effect upon the faunae of those periods, giving them different 
 or modified characteristics as compared with those of the same periods respect- 
 ively in other parts of the world. 
 
 Again, the evidence afforded by both the vertebrate and invertebrate 
 collections, and by those of the florae of all the periods named in the 
 section on a previous page, is in favor of the existence during that time of 
 a warm-temperate and uniform climate. Furthermore, the labors of the 
 field geologists have shown that there is a great degree of conformability 
 of the strata of all the subordinate groups, from those of the Carboniferous 
 to those of the Tertiary periods, inclusive ; or at least that the cases of un- 
 conformability are few and of comparatively slight degree. So great a 
 degree of uniformity in such important conditions as these having prevailed, 
 it is not strange that the groups of strata of the different periods respect- 
 
78 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 ively are not in all cases clearly defined by faunal characteristics, even 
 although they may be separated by sufficiently distinct physical characters 
 by the field geologist 
 
 The periods are, as a rule, very clearly separated from each other by 
 faunal characteristics, there being a partial exception in the case of those 
 of the upper group of the Cretaceous period and the lower group of the 
 Tertiary. But these facts will be noticed under appropriate heads on fol- 
 lowing pages. 
 
 Our investigations further show that certain faunal characteristics which 
 have hitherto been relied upon to fix the geological age of strata of marine, 
 brackish and fresh water origin, respectively, are not parallel. In other 
 words, our collections contain types or forms of fresh and brackish water 
 origin that have been regarded' as peculiar to the Tertiary period, which 
 were obtained from strata that underlie those containing such marine types 
 as are universally regarded as peculiar to Mesozoic age; showing conclu- 
 sively, that so-called Tertiary fresh and brackish water types and Cretaceous 
 salt water types co-existed. The land shells also that have been obtained 
 from strata herein classified as Cretaceous, are of Tertiary or even of still 
 more recent type. These facts have made it especially difficult to fix the 
 period of our terrestrial, and fresh and brackish water fossils with satisfactory 
 precision, if they were- new species and obtained from unique and isolated 
 localities. 
 
 A striking peculiarity of the strata of the Plateau Province, is the large 
 proportion among them of fresh and brackish water deposits. So far as at 
 present known, all the strata of Carboniferous age are of marine origin, the 
 first unmistakably fresh water accumulations yet discovered in the Plateau 
 Province being of Jurassic age. The only species obtained from these fresh 
 water strata is a f/m'o, which is one of ordinary recent type; as is also 
 another species of Unio and some Viviparine shells, described by Meek and 
 Hayden, from the valley of the Upper Missouri River. These facts again 
 illustrate the comparatively small value that can be placed upon fresh water 
 invertebrate forms as indices of the passage of geological time. 
 
 Most of the Mesozoic strata were evidently deposited in water that was 
 salt by virtue of having been a part of, or in communication with, the open 
 
GENERAL OBSERVATIONS. 79 
 
 ocean; but it is not improbable that many of the brackish water accumula- 
 tions, especially those of late Cretaceous and early Tertiary age, may have 
 been made in land-locked waters which had their saline character continued 
 from former times by the leachings of surface drainage, similar to that of 
 Great Salt Lake, but in a far less proportionate degree. This idea is sug- 
 gested by the fact that the final change to exclusively fresh water lacustrine 
 deposits was so gradual that all the former brackish water species, among 
 which no open-sea forms have been discovered, passed away without any 
 perceptible physical change in the accumulating strata. 
 
 LOWER SILURIAN AGE. 
 
 The Lower Silurian age is represented in the collections only by a very 
 few imperfect fossils from Kwagunt Valley, Grand Canon of the Colorado, 
 Arizona. The Brachiopod genera Lingulella and Obolella are recognized 
 with a good degree of certainty, and, distributed through the small masses 
 of rock which contain them, there are apparently fragments of two or three 
 other species. 
 
 These specimens doubtless belong to the Primordial period, and possess 
 much interest as regards the geological age of the rocks which underlie and 
 overlie them. 
 
 UPPER SILURIAN AND DEVONIAN AGES. 
 
 The present collections contain no fossils from strata of either Upper 
 Silurian or Devonian age, but it is not improbable that rocks of these ages 
 will yet be discovered in the Plateau Province. x 
 
 CARBONIFEROUS AGE. 
 
 The collections contain fifty species from strata of Carboniferous age, 
 much the greater part of which are from the Lower Aubrey Group. A few 
 are from the Upper Aubrey, and a still less number from the Red Wall 
 Group, while none are reported from the Lodore Group. 
 
 A large proportion of all these fossils are specifically identical with well- 
 known forms in the strata of the Carboniferous or Coalmeasure period in 
 the States of the Upper Mississippi Valley; and all but two of them belong 
 to such types as we might naturally expect to find in the equivalents of 
 
80 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 those strata. These two belong to the two genera respectively Archimedes 
 and AmplexuSj the former of which, especially, 'has been regarded as an. 
 exclusively Subcarboniferous genus; and yet they are found in the Lower 
 Aubrey Group, nearly three thousand feet above the base of the Carbonifer- 
 ous series, and also above, and mingled with, types that have not hitherto 
 been found in strata so low as the Subcarboniferous 
 
 Few or none of the fossils of the collections are of such a character as 
 to suggest the Permian age of the strata from which they were obtained, 
 not even those of the Upper Aubrey Group. I have elsewhere shown* 
 that the prevalence of certain types which have been relied upon to prove 
 the Permian age of the strata containing them may be due to peculiar 
 physical conditions, and I therefore regard it as not improbable that the 
 time of the Permian period may be represented in the Plateau Province 
 by the Upper Aubrey Group, although the distinguishing types are want- 
 ing there. In view also of the mixture which we find, of "Carboniferous and 
 Subcarboniferous types in the same strata, it seems probable that the time 
 of the whole Carboniferous age, including its three periods, Subcarbonifer- 
 ous, Carboniferous, and Permian, is collectively represented by the four 
 groups recognized in the Plateau Province. 
 
 It seems probable, therefore, that, although some localities in Nevada 
 and Montana have furnished collections of almost exclusively Subcarbonifer- 
 ous types, we shall not, as a rule, be able to define in this region, the three 
 periods into which the age is divided in other parts of the world. It seems 
 also probable that no divisions of the Carboniferous strata of the Plateau 
 Province can be made that will represent geological periods, well defined 
 upon paleontological grounds, either corresponding to those already estab- 
 lished in other parts of the world, or differing from them. 
 
 MESOZOIC AGE. 
 
 TRIASSIC PERIOD. 
 
 Some small collections of fossils which possess peculiar interest were 
 collected by Mr. E. E. Howell, in 1874, from the following localities in Utah: 
 At Toquerville ; Virgin River, south of Toquerville ; near Workman's 
 
 * Geology of Io\vn. 1870, vol. i, page 24'J, 
 
GENERAL OBSERVATIONS- 81 
 
 ranch, ten miles east of Toquerville, and also two miles west of Kanab. 
 They were obtained from the lower portion of the Shinarump Group, 
 the lowest group of Triassic strata in the Plateau Province. The specimens 
 are all very imperfect, but the following genera have been recognized : 
 Pcntacrimis, RJiynclionella, Camptonwtes, and Myalina. Besides these there 
 were fragments of other conchifers, the generic relations of which are not 
 
 recognizable. The specimens of Pentacrinus consist only of joints of the 
 
 
 
 column, like those of P. asteriscus Meek and Hayden, so common in the 
 Jurassic strata of the same region, and, indeed, seem undistinguishable from 
 those of that species. So far as can be determined, the fragments of liliyn- 
 chonclla may be those of the Jurassic, R. gnathopliora Meek, and those of 
 Camptonectes may belong to any one of the several species known to exiat 
 in the Jurassic strata of the Plateau Province. In short, if the collections 
 had been placed in my hands for determination, without any statement of 
 their stratigraphical position, I should have referred them to the Jurassic 
 period with no other doubts than those suggested by the imperfection of the 
 specimens. If their stratigraphical position is correctly reported, which I 
 know no reason to doubt, it seems certain that the strata containing them 
 
 ' C 
 
 ought to be referred to the Jurassic rather than to the Triassic period. 
 Before such an important conclusion as this is reached, however, it will be 
 necessary to secure more perfect and complete collections. 
 
 JURASSIC PERIOD. 
 
 Twenty-seven species have been recognized among the Jurassic fossils 
 of the collections, at least four of which are new. With the exception of 
 
 * 
 
 two Echinoderms all the species are molluscan. 
 
 Considerable interest attaches to the fact that a species of Unio has 
 been obtained from strata of this period at Flaming Gorge, Utah, indicating 
 the presence of fresh water at that point at one time during the period. 
 The fact is also of still further interest as indicating that the fresh-water 
 molluscan types which became so prevalent in the Tertiary period were 
 introduced early in Mesozoic time if not before. 
 
 CRETACEOUS PERIOD. 
 
 A much larger number of species, all of which arc molluscan, have 
 
 been obtained from strata of the Cretaceous than from those of any one of 
 Or a 
 
82 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 the other periods represented in the collections. The entire absence of all 
 articulate and molluscoidean species from all the Cretaceous collections is 
 quite remarkable. All four of the groups of strata are represented in the 
 collections, those from the Henry's Fork Group containing the smallest num- 
 ber of species. 
 
 The groups as a rule appear to be separated by good paleontological 
 as well as physical characteristics. Those of the Henry's Fork and Sulphur 
 Creek Groups, however, are similar, and the dividing line between the Salt 
 Wells and Point of Rocks Groups appears to be indistinct as regards generic 
 and family types; but, with very few exceptions, the species have not been 
 found to pass from one group to another. The exceptions thus far noticed 
 are those of species that have* a very wide geographical as well as an un- 
 usually great vertical range. 
 
 The Henry's Fork and Sulphur Creek Groups, so far as they have been 
 examined, appear to have been wholly open-sea deposits, no genera of 
 brackish water habitat, except Ostrea and Anomia, which are also open-sea 
 forms, having been discovered in any of the strata. The Sulphur Creek 
 Group is also remarkable for containing nearly all the Cretaceous Cephalo- 
 poda of the collections; the only exceptions being a specimen of Baculites 
 ovatus Say, from the' Salt Wells Group in the valley of Red Creek, Utah, 
 and species of Scaphites from the same group two miles northwestward from 
 Salt Wells Station, Wyoming. 
 
 The Salt Wells Group is riot only remarkable for its paucity of Ceph- 
 alopods, but also in consequence of the fact that from among its strata we 
 obtain the first Cretaceous fresh- water forms. Even among the fossils of 
 some of its more distinctively marine strata, we obtain such forms as are 
 usually found in the brackish and fresh water Cretaceous and Tertiary de- 
 posits of that region. The earliest of the fresh or brackish water Cretaceous 
 deposits that have been discovered in the Plateau Province occurs among 
 strata of this group near Coalville, Utah, a fortunate exposure of which 
 afforded Mr. Meek, a few years ago, species of the genera J7nio, Cyrena, 
 Phym, Nerit'ma, &c., all having a remarkably modern aspect; but the strata 
 which contained them are immediately overlaid by those which contain 
 Inoccramus, Grypliea, Anchura, and other distinctively Mesozoic forms. 
 
GENERAL OBSERVATIONS. 83 
 
 The Point of Rocks Group is well represented in the collections by 
 molluscan species, all of which are either Conchifers or Gasteropoda. Among 
 them are a few land shells, many fresh- water species, and all but a few of 
 the remainder belong to genera of known brackish-Avater habitat. Further- 
 more, some species of these remaining few genera have been found asso- 
 ciated with brackish-water forms. It thus appears that the formerly pre- 
 vailing- marine conditions over the region that we "now call the Plateau 
 
 O O 
 
 Province began to draw to a close early in the epoch represented by this 
 group, and had well nigh ceased at its close. 
 
 A good illustration of this gradual change is presented by the strata of 
 the Point of Rocks Group at Upper Kanab, Utah, where, toward the base 
 of the series exposed, the fossils are mostly marine; above these a greater 
 proportion of brackish-water forms are introduced; still higher up fresh-water 
 forms prevail, and the upper strata contain only fresh water and land shells; 
 the deposition of all the strata having evidently been continuous and uninter- 
 rupted. 
 
 Among the more interesting observations that have been made in rela- 
 tion to the fresh water and land shells of this epoch of the Cretaceous period, 
 are those concerning the great differentiation of types that had thus early 
 taken place. To so great a degree had this differentiation then attained 
 that the species of Unio, Helix, Pliysa, &c., seem to have been as diversified 
 and well developed as they are at the present time. Indeed the species of 
 these genera are so closely like some of those now living that they need 
 only the fresh condition of recent shells to remove all suspicion of their 
 great antiquity from the mind of the casual observer. 
 
 After the foregoing statements concerning the faunal characteristics of 
 the Point of Rocks Group, one might naturally inquire for the reasons that 
 have led to its reference to the Cretaceous rather than to the Tertiary period. 
 Laying aside all considerations suggested by the vertebrate and floral remains 
 that have been collected from its strata, the reply may be briely stated thus: 
 There is no physical break between this group and the Salt Wells Group 
 below it. Its strata contain at least three species of Inoceramus, which 
 genus has never been known in strata of later date than the Cretaceous 
 period. Odontolmsis, a species of which has been obtained from nenr the 
 summit of the group, is regarded as a Cretaceous genus; and in view of the 
 
84 INVERTED KATE PALEONTOLOGY. [WHITE. 
 
 facts before stated, that land and fresh and brackish water mollnsks are 
 comparatively valueless as indices of the passage of geological time, the 
 presence of no known forms in its strata forbid the reference of this group to 
 the Cretaceous period. 
 
 CENOZOIC AGE. 
 
 TERTIARY PERIOD. 
 
 The collections of Tertiary fossils contain sixt^ species, exclusive of 
 those that were obtained from localities beyond the limits of the Plateau 
 Province. All of them are either brackish or fresh water species ; the only 
 truly marine forms of Tertiary age being those obtained at Bijou Basin, 
 Colorado, which have already been noticed, and, as they are also described 
 and catalogued on following pages, they will not be considered in the fol- 
 lowing general remarks, which are intended to apply mainly to that portion 
 of the Pro*vince which lies north of the Uinta Mountains. 
 
 One-half of all these species were obtained from the Bitter Creek 
 Group, the lowest group of the Tertiary series. This difference in the rel- 
 ative abundance of species in the different groups is of course due primarily 
 to the conditions under which the species lived, but evidently in large part 
 also to the very much greater geographical extent, as well as greater thick- 
 ness, of this group than of any of the others. Among the primary condi- 
 tions referred to, an obvious one was, the continuance of the brackish 
 waters, so common in the last epoch of the Cretaceous period, into the first 
 epoch of the Tertiary in some localities, although they seem to have given 
 place to wholly fresh waters in other localities before the close of the Cre- 
 taceous period. Collections have been made from these brackish- water 
 Tertiary strata at Black Buttes. Point of 'Rocks, and Rock Spring, all in 
 the valley of Bitter Creek, Wyoming, and where they reach a thickness of 
 from five to seven hundred feet above the base of the Tertiary series. The 
 species are clearly distinct from all others, either of this or any of the other 
 Tertiary groups; but it is not to be denied that, although they are also all 
 specifically distinct from any of the species found in the underlying Point 
 of Rocks Group of the Cretaceous period, there is a prevalent similarity of 
 type between the fossils of the two groups that is apparent upon merely 
 casual inspection. 
 
GENERAL OBSERVATIONS. 85 
 
 No true or exclusively marine species have been discovered in these 
 brackish-water Tertiary strata, and it is probable that the waters in which 
 they were deposited were previously cut off from the open sea, but yet 
 retaining to a great degree their former saltness. The genera thus far dis- 
 covered are Ostrea, Anomia, Corbula, Corbicula (Leptesthes), Cyrena (Velori- 
 tma), and Neritina, besides the more exclusively fresh-water genera Unio, 
 Goniolasis, Viviparus, Tulotoma, and Leioplax? 
 
 The final cliange to a wholly fresh, from the brackish water condition, 
 which was never to be resumed, was so gradual that no physical difference 
 appears in the strata accumulated under both conditions ; but from and 
 after that change a uniformity of molluscan type prevailed through all the 
 subsequent epochs of the Tertiary period, as represented in the Plateau 
 Province, that is really remarkable. It is especially so if, as Professor 
 Powell has suggested from stratigraphical considerations, these Cenozoic 
 groups represent the whole of what is generally known as the Tertiary 
 period. Here and there, at different places in each of the Tertiary groups, 
 except the Brown's Park group, which, because of its barrenness of fossils, 
 is not included in this discussion, a few locally restricted species have been 
 found, amounting to a considerable number in the aggregate. But prevail- 
 ing at numerous horizons through all these groups after the brackish -water 
 condition had ceased, and often in. great profusion, are the three molluscan 
 genera UniOj Viviparus, and Goniobasis, which are almost invariably imme- 
 diately associated and almost as invariably without other faunal associates 
 except occasionally a large discoid Planorlis. 
 
 The Unios are of several species, which are denned by characters simi- 
 lar to those upon which accepted recent species of the genus are established; 
 but I have been unable to discriminate with entire satisfaction more than 
 one species each of Goniobasis and Viviparus among these prevailing forms 
 in the northern part of the Plateau Province, from the upper part of the 
 Bitter Creek Group to the top of the Bridger Group, inclusive, with the pos- 
 sible exception of Viviparus Wyominfjensis Meek, from the Bridger Group. 
 The Planorbis just mentioned I have usually referred to P. spectabUis Meek, 
 but in the Bitter Creek Group, especially south of the Uinta Mountains, a 
 variety occurs with fewer and broader volutions, in which respect it cor- 
 
86 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 responds with the description of P. Utahensis Meek. The Vivipanis and 
 Goniobasis I have, in the following catalogue, referred respectively to F. 
 paludinceformis Hall sp. and G. tenera Hall sp. Goniobasis nodiilifera Meek 
 ( Cerithium nodidosum Hall) and G. Carteri Conrad, are regarded as syno- 
 nyms of G. tenera; and from among the thousands of examples that have 
 been collected from the strata under discussion, it would be easy to make 
 selections that, if found separately, would be taken to indicate an equal 
 number of species, as different from those as they are from each other. 
 Fortunately, however, the specimens in all cases are so abundant that other 
 selections may be made showing full intermediate gradations between all 
 the species that have been, and doubtless all that may yet be, proposed from 
 among them. 
 
 The character and extent of the variations of these species in their 
 geographical distribution, vertical range, and local association will be dis- 
 cussed in a future report. It is, therefore, sufficient now to suggest that 
 these forms will present some of the best opportunities for the zoologico- 
 historical study of certain species through a great lapse of geological time 
 that paleontology has ever furnished. 
 
 This remarkable uniformity of molluscan types through all the groups, 
 together with their almost exact identity with recent types of fresh- water 
 mollusca, seems at first view to present an argument against the supposition 
 that those Cenozoic deposits occupied the whole of Tertiary time, when con- 
 sidered only in relation to the invertebrate remains ; but the slight value of 
 fresh-water molluscan forms in such generalizations has already been shown. 
 If relied upon at all, their modern aspect would seem to indicate late Ter- 
 tiary time only, while, on the other hand, the physical connection tff the 
 lowest group with the uppermost group of Cretaceous strata is such as to 
 leave no doubt that the former represents the earliest epoch of Tertiary time. 
 
 Besides this several of the species found in the brackish-water layers 
 at the base of the Bitter Creek Group are closely related to species found 
 in similar deposits in Slavonia and referred to the Eocene Tertiary by 
 Brusina.* (See "Fossile Binnen-Mollusken aus Dalmatien, Kroatien, und 
 Slavonien von Spiridion Brusina, Agram, 1874.") 
 
 * It is mi interesting fact that these collections of Tertiary fresh water niollusks iu Slavonia possess 
 many Unione and Vivipariue forms that arc of living American, and not European types, while all the 
 American fossil fresh water forms with which I am acquainted are of American recent types. 
 
. GENERAL OBSERVATIONS. 87 
 
 By comparing the invertebrate fauna of those fresh water Tertiary 
 deposits with the faunae of existing fresh waters we observe the entire 
 absence from our collections of all articulates, except a species of Cypris 
 and the insects discovered by Mr. Cleburn. The list of Molluscan genera 
 found in those ancient lakes compares closely with those of the great existing 
 American lakes, notwithstanding the fact that the floral remains of the 
 former indicate a uniform and much milder climate than now exists in either 
 of the two regions. 
 
 Thus far no well defined fluvatile deposits have been discovered, but it 
 is probable that those fresh water species found among brackish water forms 
 constituted portions of the molluscan faunae of rivers that flowed into the 
 ancient lakes or estuaries, because they are specifically different from, and 
 more various than, those of the purely fresh water deposits. This sugges- 
 tion is supported by the well-known fact that the molluscan types of lakes are 
 fewer than those of rivers, while the differentiation is yet greater in brackish 
 and greater still in marine waters. 
 
 In closing these remarks upon the Ternary period a question arises 
 similar to the one briefly considered at the close of the remarks upon the 
 Cretaceous period, namely : Why has the dividing line between the strata 
 of the Tertiary and Cretaceous periods been drawn where it is rather than 
 at some horizon either above or below it ? 
 
 The answer is nearly the same as in the former case There is no 
 physical break in the Cretaceous strata, from the base of the series to the 
 top of the upper, or Point of Rocks Group, at which horizon there is at all 
 observed points, extending over a large region, considerable unconforrna- 
 bility by erosion of the lower strata of the Bitter Creek Group, upon the 
 upper strata of the Point of Rocks Group. 
 
 The separation of the two periods, as represented by the strata of the 
 .Plateau Province, is a physical rather than a paleontological one. Upon 
 purely paleontological ground it is difficult to indicate precisely where the 
 line should be drawn, but it should evidently be somewhere near the one 
 indicated in Professor Powell's section. This being the case, and it being 
 necessary to draw such a line, it is more rational to draw it upon a line of 
 a physical break than through conformable strata either above or below it. 
 
88 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 CATALOGUE OF THE FOSSILS COLLECTED BY THE 
 VARIOUS PARTIES IN THE FIELD DURING THE 
 YEARS 1868 TO 1875, INCLUSIVE. 
 
 CARBONIFEROUS AGE. 
 
 CARBONIFEROUS PERIOD. 
 RED WALL GROUP. 
 
 1. Chaetetes. milleporaceus Troost. Gypsum Canon, Colorado River, 
 Utah. The specimens have their characters obscured by silieification, but 
 they doubtless belong to this species. It also occurs in the Lower Aubrey 
 Group. (See No. 4.) 
 
 2. Syringopora multattenuata McChesney. Gypsum Canon, Colorado 
 River, Utah. 
 
 3. CampophyUum f. Cataract Canon, Utah. A large species, 
 
 larger than C. torquium Owen, but the specimens are too imperfect for full 
 specific description. 
 
 LOWER AUBREY GROUP. 
 
 4. Chaetetes milleporaceus Troost. Split Mountain Canon, Green River, 
 Utah. Also obtained from the Red Wall Group. (See No. 1.) 
 
 5. Fistulipora f. Confluence of Grand and Green Rivers, Utah. 
 
 Weathered specimens. . 
 
 6. Syringopora ?. Confluence of Grand and Green Rivers, 
 
 Utah. Specimens consisting of rather small, flattened, or subspherical 
 masses. Tubes small and much distorted, but imperfect by silieification. 
 
 7. Amplexus mplirentiformis White. Near Echo Park and at Split 
 Mountain Canon, Utah. Described on a following page. 
 
 8. Lopliopliyllum prolifemm McChesney. Confluence of Grand and 
 Green Rivers, Utah. Characters more nearly typical than those of the 
 variety called Sauridens found near Santa Fe, New Mexico. 
 
 9. Lithostrotion ? York, Utah ; west base of Wasatch range. 
 
 10. Acervularia f. Split 'Mountain Canon, Green River, Utah. 
 
CATALOGUE OF FOSSILS. 89 
 
 11. Archceocidaris cratis White. Confluence of Grand and Green 
 Rivers, Utah. Described on a following page. 
 
 12. Arckaocidarw trudifer White. Confluence of Grand and Green 
 Rivers, Utah. Specimens consisting only of imperfect spines. 
 
 13. Erisocrinus typiis Meek and Worthen. Confluence of Grand and 
 Green Rivers, Utah. The type specimens of Meek and Worthen were 
 obtained from the Coal-measures of Illinois, and consisted only of calyces. 
 Ours shows about two and a half centimeters in length of the arms, each of 
 which consists of a double, interlocking series of pieces ; the arms when 
 closed lying so closely together as to leave only a linear suture between 
 them. 
 
 14. Scapliiocrinus carlonarius Meek and Worthen. Confluence of 
 Grand and Green Rivers, Utah. 
 
 1 5. ^Eiipacliycrinus platylasis White. Confluence of Grand and Green 
 Rivers, Utah. Described on a following page. 
 
 16. Polypora f. Confluence of Grand and Green Rivers, Utah 
 
 A large specimen, having unusually large fenestrules. Obverse side only 
 shown. 
 
 17. Fenestella ?. -Near Echo Park, Utah. Obverse side only 
 
 shown. 
 
 18. Archimedes ?.- Near Echo Park, Utah. Specimens consist 
 
 of two axes only, one of which is dextral and the other sinistral in its volu- 
 tions. They are, however, both referred to one species. 
 
 ] 9. Discina f. Bee-hive Point, near Horseshoe Canon, Utah. 
 
 A single lower valve. 
 
 20. Productus panctatus Martin. Confluence of Grand and Green 
 Rivers, Utah. 
 
 21. Prodiictus longispinus Sowerby ?. Near Echo Park and at the con- 
 fluence of Grand and Green Rivers, Utah. 
 
 22. Prodiictus costatus Sowerby? Near Echo Park, Utah. The speci- 
 mens consist of the ordinary American forms generally referred to that 
 species, but are probably distinct from it. 
 
 23. Prod net us costatus var. Near Echo Park, Utah. Like No. 22 in 
 
90 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 essential characters, except that the radiating costse are reduced in size to 
 that of raised striae. 
 
 24. Productus Prattenianus Norwood. Confluence of Grand and Green 
 Rivers, Utah. Some of the specimens possess the median row of spines or 
 nodes upon the ventral valve, like those which Dr. Newberry named P. 
 nodosus. 
 
 25. Productus semireticulatus Martin. Confluence of Grand and Green 
 Rivers, Utah. All the examples are of the variety named P. Ivesii by Dr. 
 Newberry. 
 
 26. Productus Nebrascensis Owen. Confluence of Grand and Green 
 Rivers, Utah. 
 
 27. Productus muricatus Norwood and Pratten. Near Echo Park, Utah. 
 
 28. Productus multistriatus Meek. Confluence of Grand and Green 
 Rivers, Utah. 
 
 29. Chonetes granulifcra Owen. Confluence of Grand and Green 
 Rivers, Utah. 
 
 30. Chonetes platynota White. Near Echo Park, Utah. 
 
 31. Hemipronites crinistria Phillips. Near Echo Park and at the con- 
 fluence of Grand and Green Rivers, Utah. It also occurs in the Upper 
 Aubrey Group. (See No. 49.) 
 
 32. Meekella striatocostata Cox. Confluence of Grand and Green 
 Rivers, Utah. 
 
 33. Spirigera sultilita Hall. Confluence of Grand and Green Rivers, 
 and near Echo Park, Utah. Occurs also in the Upper Aubrey Group. 
 (See No. 50.) 
 
 34. Spirifer cameratus Morton. Confluence of Grand and Green Rivers, 
 Utah. 
 
 35. Spirifer Eockymontanus Marcou. Split Mountain Canon and near 
 Echo Park, Utah. Occurs also in the Upper Aubrey Group. (See No. 51.) 
 
 36. Spiriferina Kentuckensis Shumard. Confluence of Grand and Green 
 Rivers, Utah. Occurs also in the Upper Aubrey Group at the same locality. 
 (See No. 52.) 
 
 37. Avicidopecten occidentalis Shumard. Two miles above Belle view, 
 Utah. 
 
 ^ 
 
CATALOGUE OF FOSSILS. 91 
 
 38. Myalina ?. Confluence of Grand and Green Rivers 1 , Utah. 
 
 The specimens have the aspect of M. rectirvirostris Meek and Worthen, but 
 all of them have lost their beaks. (See No. 53.) 
 
 39. Allorisma subcuneata Meek and Hay den? Confluence of Grand 
 and Green Rivers, Utah. The examples of the collection agree with those 
 of this species from the typical localities, as given by Meek and Hayden, 
 and they also agree very nearly with the description and figures given by 
 Dr. Newberry of A. capax. 
 
 40. Edmondia Aspenwallensis Meek. Confluence of Grand and Green 
 Rivers, Utah. 
 
 41. Pleurophorns ?. Confluence of Grand and Green Rivers, 
 
 Utah. The species is probably new, but the specimens are too imperfect 
 for full description. 
 
 42. Scliizodus Wheeleri Swallow. Confluence of Grand and Green 
 Rivers, Utah. 
 
 43. Betterophm f. Confluence of Grand and Green Rivers, 
 
 Utah. 
 
 44. Enomplialus f. Confluence of Grand and Green Rivers, 
 
 Utah. The specimens are imperfect, but are probably those of E. luxus 
 White. 
 
 45. Pleurotomaria excelsa Newberry. Confluence of Grand and Green 
 Rivers, Utah. 
 
 46. Naticopsis remcx White. Confluence of Grand and Green Rivers, 
 Utah. Described on a following page. 
 
 47. PliMpsia - -f. Near Echo Park, Utah. 
 
 UPPEE AUBEEY GROUP. 
 
 48. Distinct f. Bee-hive Point, near Horseshoe Canon, Utah. 
 
 49. Hemipronites crinistria Phillips. Bee-hive Point, near Horseshoe 
 Canon, Utah. Occurs also in the Lower Aubrey Group. (See No. 31.) 
 
 50. Spirigera sitbtilita Hall. Bee-hive Point, near Horseshoe Canon, 
 Utah. Occurs also in the Lower Aubrey Group. (See No. 33.) 
 
 51. Spirifer Rodcymontanus Marcou. Bee-hive Point, near Horseshoe 
 Canon, Utah. Occurs also in the Lower Aubrey Group. (See No. 35.) 
 
92 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 52. Spiriferina Kentuckensis Shumard. Confluence of Grand and Green 
 Rivers, Utah. Also occurs in the Lower Aubrey Group at the same locality. 
 (See No. 36.) 
 
 53. Myalina ?. Confluence of Grand and Green Rivers, Utah. 
 
 Occurs also in the Lower Aubrey Group at the same locality. (See No. 38.) 
 
 54. JEdniondia f. Confluence of Grand and Green Rivers, Utah. 
 
 55. Belleroplion Montfortianus Norwood and Pratten. Confluence of 
 Grand and Green Rivers, Utah. The specimens are imperfect, 'but have 
 apparently the markings and other characteristics of this species as it occurs 
 in the Coalmeasures of the Mississippi Valley, but the shell is evidently more 
 elongate or less compact. 
 
 56. Belleroplion carbonarim Cox, var. subpapillosus White. Bee-hive 
 Point, near Echo Canon and near Echo Park, Utah. Also at Junction 
 Mountain and near Diamond Peak, Northwestern Colorado. This variety 
 differs from the typical forms of the species in its larger size and in having 
 that part of the last volution, which is plain in the typical shell, marked 
 .with distant, slightly-raised papillae/arranged in rows corresponding to and 
 
 continuous with the revolving striae. 
 
 i 
 
 MESOZOIC AGE. 
 
 JURASSIC PERIOD. 
 FLAMING GORGE GROUP. 
 
 57. Pentacrinus asterisous Meek and Hayden. Flaming Gorge ; Santa 
 Clara River, two miles below Gunlock ; Diamond Valley ,- Lower Potato 
 Valley ; " White Hills," south of Twelve-mile Creek, near Gunnison ; three 
 or four miles south of Kanara, Utah ; and at the Vermilion Hog-backs, 
 Northwestern Colorado. The specimens consist only of joints of the col- 
 umn, the only part of the species yet discovered. 
 
 58. Spine of Echinoid, too indefinite for either specific or generic rec- 
 ognition. Santa Clara River, two miles below Gunlock, Utah. 
 
 59. Eliynclionella gnatlioplwm Meek. Flaming Gorge, Utah, and Ver- 
 milion Hog-backs, Northwestern Colorado. 
 
CATALOGUE OF FOSSILS. 93 
 
 60. EJiynclionella Myrina Whitfield. Vermilion Hog-backs, Northwest- 
 ern Colorado. 
 
 61. Ostrea strigilecula White. Island Park and Flaming Gorge, Utah; 
 and Vermilion Hog-backs, Northwestern Colorado. ' 
 
 62. Ostrea (Alcdryonia) procumbens White. Vermilion Hog-backs, 
 Northwestern Colorado. Shell of moderate size, irregularly ovate in mar- 
 ginal outline ; margins coarsely dentate ; valves moderately thick, usually 
 attached by nearly the whole surface of the lower one. 
 
 63. Camptonedes stygius White. Lower end of Long Valley ; mouth 
 of Thistle Creek, Spanish Fork Canon ; Upper Kanab ; and three or four 
 miles south of Kanara, Utah. 
 
 64. Camptonedes bellistriatus Meek and Hayden. Three or four miles 
 south of Kanara, Utah. 
 
 65. Camptonedes platessiformis White. North base of Aquarius Pla- 
 teau, Southern Utah. Resembles C. platessa White in its surface-markings, 
 and C. Stygius White in its marginal outline. 
 
 66. Gervillia 1. Nortli base of Aquarius Plateau, Southern 
 
 Utah. Resembles G. Montanacnsis Meek, but the axis of the shell is more 
 oblique to the hinge-line, and the wing narrower than in that species. 
 
 67. Pinna - -?. Mouth of Thistle Creek, Spanish Fork Canon, 
 Utah. Surface radiately ribbed both above and below the median angle; 
 probably a new species, but the specimens are too imperfect for satisfactory 
 description. 
 
 68. Modiola sttbimbricata Meek. Vermilion Hog-backs, Northwestern 
 Colorado. 
 
 69. Myophoria f. Island Park, Utah. * 
 
 70. Trigonia Americana Meek. Flaming Gorge, Utah. 
 
 71. Trigonia Montanaensis Meek. North base of Aquarius Plateau, 
 Utah. 
 
 72. Trigonia Conradi Meek and Hayden. Flaming Gorge, Utah. 
 
 73. Trigonia f. Santa Clara River, two miles below Gunlock, 
 
 Utah. 
 
 74. Unio Stewardi White. Flaming Gorge, Utah. Described on a fol- 
 lowing page. 
 
94 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 75. Trigonella f. Island Park, Utah. Shells rather small-exte- 
 rior nearly perfect, but the hinge is unknown, and they are referred to this 
 genus provisionally. 
 
 76. Undetermined Concliifers. Two species. Flaming Gorge ; north base 
 of Aquarius Plateau; Square-top Butte, east base of Aquarius Plateau, 
 Utah. 
 
 77. Undetermined Conchifer. Different from No. 76. Island Park, Utah. 
 
 78. Myacitcs ?. South base of Thousand-lake Mountain, Utah. 
 
 79. Neritimt- -?." White Hills", south of Twelve-mile Creek, 
 near Gunnison, Utah; and Vermilion Hog-backs, Northwestern Colorado. 
 
 80. Neritinaff Powelli White. Mouth of Thistle Creek, Spanish Fork 
 Canon, Utah. Described on a following page. 
 
 81. Undetermined Gasteropods. Two species, very small, and the speci- 
 mens numerous. Mouth of Thistle Creek, Spanish Fork Canon, Utah. 
 
 82. Eelemnites densus Meek and Hay den. Island Park and Flaming 
 Gorge, Utah; and Vermilion Hog-backs, Northwestern Colorado. 
 
 83. Ammonites cordiformis Meek and Hayden. A small fragment of the 
 inner volutions. Vermilion Hog-backs, Northwestern Colorado. 
 
 CRETACEOUS PERIOD. 
 
 HENRY'S FORK GROUP. 
 
 84. Ostrea prudentia White. Head of Water-pocket Can on, Southern 
 Utah. 
 
 85. Grypliea Pitclieri Morton. Near Twin Mesas; Upper Pine Creek; 
 near Last,Chance Creek; head of Water-pocket Canon and Lower Potato 
 Valley, Southern Utah. The specimens are numerous, and show the usual 
 extreme variations. It occurs also in the Sulphur Creek Group. (See No. 9 7.) 
 
 86. Exofiyra Icevinscula Roemer. Lower Potato Valley and south base 
 of Mount Killers, Southern Utah. It occurs also in the Sulphur Creek Group. 
 (See No. 98). 
 
 87. Exogyra ponderosa Roemer. Head of Water-pocket Canon, South- 
 ern Utah. It occurs also in the Sulphur Creek Group, in Utah, and was 
 obtained from a locality in Middle Park, Colorado. (See Nos. 99 and 202.) 
 
CATALOGUE OF FOSSILS. 95 
 
 88. Plicatula Jiyclrotheca White. Head of Water-pocket Gallon, South- 
 ern Utah. Described on a following page. 
 
 89. Inoceramus Howelli White. Lower Potato Valley and Upper Pine 
 Creek, Utah. Described on a following page. 
 
 00. Avicula linguiformis Shumard. Lower Potato Valley and Sink 
 Spring, Utah. 
 
 01. Camptoncctes platcssa White. Head of Water-pocket Canon, South- 
 ern Utah. 
 
 02. Undetermined Concliifers. Lower Potato Valley, Utah. 
 
 03. Cardium f. Head of Water-pocket Canon, Southern Utah. 
 
 
 
 A rather large subspinous species, probably new, but the specimens are all 
 imperfect. 
 
 04. CaUista Detvcyi Meek and Hay den. Head of Water-pocket Canon, 
 Southern Utah. The specimens consist only of casts in sandstone. 
 
 05. Area f. Hea.d of Water-pocket Canon, Southern Utah. 
 
 An elongate species, represented only by a cast in sandstone. 
 
 SULPHUR CREEK GROUP. 
 
 06. Ostrea congesta Conrad. Fold, ten miles west of Black Bluff, Green 
 River, and Island Park, Utah; base of Diamond Peak and near Vermilion 
 Canon, Northwestern Colorado. The specimens from the last-named locality 
 are unusually large, and a few of them were found free, but most of them 
 were, as usual, found attached to fragments of Inoceramus deformis. The 
 species occurs also in the Point of Rocks Group, Utah, in Western Kansas, 
 and in Middle Park, Colorado. (See Nos. 150 and 200.) 
 
 07. Gryplica Pitrlieri Morton. Near Black Bluff, on Green River; 
 Upper Kanab; fold, ten miles west of Black Bluff and Sink Spring, Utah. 
 It also occurs in the Henry's Fork Group. (See No. 85.) 
 
 08. Exogyra l&viuscida Roemer. Upper Kanab, and near Black Bluff, 
 011 Green River, Utah. Occurs also in Henry's Fork Group, Utah. (See 
 No. 86.) 
 
 00. Exogyra ponderosa Roemer. Upper Kanab, Utah. It occurs also 
 in Henry's Fork Group, Utah, and in Middle Park, Colorado. (See Nos. 
 87 and 202.) 
 
90 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 100. Inoceramus deformis Meek. Fold ten miles west of Black Bluff on 
 Green River, and Island Park, Utah. Base of Diamond Peak and near 
 Vermilion Canon, Northwestern Colorado. It accurs also at the base of the 
 Point of Rocks Group, near Coalville, Utah; in western Kansas, and in Mid- 
 dle Park, Colorado. (See Nos. 167 and 203.) 
 
 101. Lucina subundata Hall and Meek. Upper Kanab and Thistle 
 Creek, Utah. A species probably identical with this occurs in the Salt Wells 
 Group at Coalville, Utah. (See No. 132.) 
 
 102. Leiopistlia Meckii White. Upper Kanab and Sink Spring, Utah. 
 
 103. Turnus splienoideus White. Upper Kanab, Utah. Described o^n 
 a following page. 
 
 104. Lunatia concinna Hall and Meek. Sink Spring, Utah. 
 
 105. AncJmraruida White. Upper Kanab, tltah, Described on a fol- 
 lowing page. 
 
 106. Anclmra proldbiata White. Upper Kanab and Sink Spring, Utah. 
 Described on a following page. 
 
 107. Turritetta Uvasana Conrad.- Upper Kanab, Utah. 
 
 108. Cassiope Whitfieldi White. Upper Kanab, Utah. 
 
 109. Pseudobuccinum Nebmsccnse Meek and Hay den. Upper Kanab, 
 Utah. 
 
 110. Baadites ovatus Say.- Fold ten miles west of Black Bluffs, Green 
 River, Sink Spring, near Twin Mesas, and Upper Kanab, Utah. Occurs 
 also in the Salt AVells Group. (See No. 157.) 
 
 111. Scapliites Warreni Meek and Hay den. Fold ten miles west of 
 Black Bluff, Green River, Utah. 
 
 112. Ammonites Woolgari Mantelll Last Chance Creek, Utah. 
 
 113. Ammonites f. Fold ten miles west of Black Bluff, Green 
 
 River, Utah. This species is of the type of A. Woolgari, but the volutions 
 are proportionally deeper and the umbilicus smaller than in that species. 
 
 114. Ammonites f. Upper Kanab, Utah, Specimens imperfect, 
 
 but they indicate a species quite different from any others in the collections. 
 
 115. Bucliiceras Swallovi Shumard. Upper Kanab, Utah. 
 
 116. Helicoceras f. Near Twin Mesas, Utah, The specimens 
 
 show two rows of long dorsal spines and a crenulated or transversely undu- 
 
CATALOGUE OF FOSSILS. 97 
 
 lated surface. They are so compressed in shale that the character of the 
 coil is not shown, and may, therefore, probably belong to the genus Crioceras. 
 
 117. Helicoceras ?. Upper Kanab, Utah. A fragment, different 
 
 from No. 116. 
 
 118. Belemnitella ?. Upper Kanab, Utah, and Sulphur Creek, 
 
 Bear River City, Wyoming. The specimens are more or less imperfect, but 
 they closely resemble, and are probably identical with, B. mucronata, so 
 common in the Cretaceous strata of New Jersey. 
 
 119. Serpula intrica White. Upper Kanab, Utah. 
 
 SALT WELLS GROUP. 
 
 120. Ostrea solemscus Meek. Coalville, Lower Salina Can on, and near 
 False Creek, Utah; Bear River City, and Hilliard Station, Wyoming. 
 
 121. Ostrea (Alectryonia) sannionis White. Weber Valley, near Coal- 
 ville, Utah. Described on a following page. 
 
 122. Ostrea (Alectryonia f. Near False Creek, Southern Utah. 
 
 The specimens are fragmentary, but they indicate an unusually large species 
 of this subgeiius. 
 
 123. GrypJiea ?. Coalville, Utah. The specimens are imperfect, 
 
 but they seem to indicate a species materially different from G. Pitclieri 
 Morton. 
 
 124. Anomia f. Coalville, Utah. 
 
 125. Inoceramus problematicus Schlotheim. Lower Salina Canon and 
 Coalville, Utah; Bear River City, Wyoming. 
 
 126. Inoceramus f. Two miles northwestward from Salt Wells 
 
 Station, Wyoming. 
 
 127. Inoceramus Gilberti White. Near Last Chance Creek, Southern 
 Utah. Described on a following page. 
 
 128. Avicula (Pseudoptera) rliytopliora Meek. Coalville, Utah. 
 
 129. Modiola (Bracliydontes) multilinigcra Meek. Coalville, Utah. 
 
 130. Area Coalvillensis White. Coalville, Utah. Described on a fol- 
 lowing page. 
 
 131. Macrodon f. Coalville, Utah. A rather large, elongate 
 
 species, represented only by a sandstone cast. 
 
 7 p G 
 
98 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 132. Lucina subundata Hall and Meekt Coalville, Utah. Apparently 
 identical with that species. (See No. 101.) 
 
 133. Cardium curtum Meek and Hayden. Coalville, Utah. 
 
 134. Cardium subcwrtmn Meek. Coalville, Utah. 
 
 135. Cyrena (Vcloritina) securis Meek. Coalville, Utah. Mr. Meek's 
 types were from the Salt Wells Group, Sulphur Creek, Bear River City, 
 Wyoming, but ours, although imperfect, seem to belong to the same species. 
 
 136. Cyrena (Veloritina) erecta White. Upper Kanab, Utah, and Hil- 
 liard Station, Wyoming. Described on a following page. 
 
 137. Tellina (Arcopagia) Utaliensis Meek. Coalville, Utah. 
 
 138. Tellina modesta Meek. Coalville, Utah. 
 
 139. Mactra arenaria Meek. Coalville, Utah. 
 
 140. Corbula nematopJiora Meek. Coalville, Utah. 
 
 141. Corbula- -f. Coalville, Utah. 
 
 142. Martesia - - f. Coalville, Utah. 
 
 143. Pliysa ?. Coalville, Utah. One imperfect example only 
 
 was found. It was associated with shells of marine type only, but it never- 
 theless seems to possess the characters of a true Pliysa. 
 
 144. Neritina Bannisteri Meek. Hilliard Station, Wyoming. The type 
 specimens of this species were obtained by Mr. Meek from among brackish 
 and fresh water forms near Coalville, Utah. No fresh, or exclusively brack- 
 ish water forms were found associated with our examples, although the geo- 
 logical horizon is doubtless identical, or very nearly so, at the two localities. 
 
 145. Neritina pisum Meek Coalville, Utah. 
 
 146. Neritina (Velatella) patelliformix Meek. Coalville, Utah. 
 
 147. Lunatia Utahensis White. Coalville, Utah. Described on a fol- 
 lowing page. 
 
 148. Anchura fusiformis Meek. Coalville, Utah, and Sulphur Creek, 
 Bear River City, Utah. 
 
 149. TurnteUa micronema Meek. Coalville, Utah. 
 
 150. Tiirritella Coalmllensis Meek. Coalville, and ten miles southeast 
 of Kanara, west of Cone Mountain, Utah. 
 
 151. Eidimella funicula Meek. Coalville, Utah. 
 
CATALOGUE OF FOSSILS. 99 
 
 152. Turbonilla (Chemnitzia) Coalvillensis Meek. Coalville, Utah, and 
 Hilliard Station, Wyoming. 
 
 153. Gyrodes depressa Meek. Coalville, Utah. 
 
 154. Fusus (Neptunea) Gabli Meek. Coalville, Utah. 
 
 155. Fusus (Neptunea) Utahensis Meek. Coalville, Utah. 
 
 156. Admetopsis gregaria Meek. Coalville, Utah. 
 
 157. Baculites ovatus Say. Below "Wall Rock," basin of Red Creek, 
 Utah. Occurs most commonly in the Sulrjhur Creek Group. (See No. 110.) 
 
 158. Scaphites f. Two miles northwestward from Salt Wells 
 
 Station, Wyoming. 
 
 POINT OF EOCKS GKOUP. 
 
 159. Ostrea congesta Conrad. Near the base of the group, Coalville, 
 Utah. The species occurs most abundantly in the Sulphur Creek Group of 
 the Plateau Province ; but it has a wide geographical, as well as a great 
 stratigraphical, range. (See Nos. 96 and 200.) 
 
 160. Ostrea - - f. Upper Kanab, Utah. 
 
 161. Ostrea ?. Bear River Vallev, near Mellis Station, where 
 
 */ * 
 
 it is associated with fresh and brackish water mollusks. 
 
 162. Ostrea Coalvillensis Meek. Coalville, Utah. 
 
 163. Ostrea insecura White. Two miles west of Point of Rocks, Wyo- 
 ming. Described 011 a following page. 
 
 164. Anomia gryphorhynclms Meek. Two miles west of Point of Rocks, 
 Wyoming. 
 
 165. Inoceramus f. Top of Aspen Mountain, but near the base 
 
 of the group, Wyoming. The species is nearly like /. sagensis Owen, but 
 the specimens are too imperfect for specific identification. 
 
 166. Inoceramus -f. Upper Kanab, Utah. It has the general 
 aspect of both I. Howelli and I. ' fragilis, but differs from both in essential 
 details. 
 
 167. Inoceramus deforms Meek. Near the base of the group, Coalville, 
 Utah. This species is most common in the Sulphur Creek Group, but it 
 has a wide geographical, as well as a great vertical, range. (See Nos. 100 
 and 203.) 
 
100 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 J68. Unio gonionotus White. Sevier Cliffs, twelve miles above Pan- 
 guitch, Utah. Described 011 a following page. 
 
 169. Unio f. Associated with the last (168), but differs from 
 
 it in its more convex beaks and in wanting the plications of that species. 
 
 170. Unio l)elliplicatus Meek. Bear River Valley, near Mellis Station, 
 Wyoming. 
 
 171. Unio Vetustus Meek. Bear River Valley, near Mellis Station, 
 Wyoming, and Canon of Desolation, Utah. 
 
 172. Cyrena (Veloritina) Durkeei Meek. Bear River Valley, near 
 Mellis Station, Wyoming. 
 
 173. Cyrena (Veloritina) f. Upper Kanab, Utah. 
 
 174. Cyrena (Veloritina) cytlieriformis Meek and Hayden. Two miles 
 west of Point of Rocks, Wyoming. 
 
 175. Corbula undlfera Meek. Rock Spring, Wyoming. 
 
 176. Corbula pyriformis Meek. Bear River Valley, near Mellis Station, 
 Wyoming. 
 
 177. Corbula tropidopliora Meek. Two miles west of Point of Rocks, 
 Wyoming. 
 
 178. Limncea ?. Upper Kanab, Utah. 
 
 179. Limnaa f. Bear River Valley, near Mellis Station, Wyo- 
 ming. 
 
 180. Planorbis (Batliyompliahis) Kanabcnsis White. Upper Kanab, 
 Utah. Described on a following page. 
 
 181.. Pliysa Kanabensis White. Upper Kanab, Utah. Described on a 
 following page. 
 
 ] 82. Pliysa ?. Bear River Valley, near Mellis Station, Wyo- 
 ming. 
 
 183. Pliysa ?. Upper Kanab, Utah. Associated with No. 181, 
 
 but it is a larger species, and has a much shorter spire, the volutions of 
 which are more broadly shouldered on the proximal side of the suture. 
 
 184. Rliytopliorus prisons Meek. Bear River Valley, near Mellis Sta- 
 tion, Wyoming. 
 
 185. Rliytopliorus Meekii White. Bear River Valley, near Mellis Sta- 
 tion, Wyoming. Described on a following page. 
 
CATALOGUE OF FOSSILS. 101 
 
 186. Helix f. Canon of Desolation, Utah. 
 
 187. Helix Kanabensis White. Upper Kanab, Utah. Described on a 
 following page. 
 
 188. Goniobasis nitidula Meek. Bear River Valley, near Mellis Station, 
 Wyoming. 
 
 189. Goniolasis insculpta Meek. Rock Spring, AYyoming. 
 
 190. Goniobasis chrysalis Meek. Bear River Valley, near Mellis Sta- 
 tion, Wyoming. 
 
 191. Goniobasis Nebrascensis Meek and Hayden. Canon of Desolation, 
 Utah. 
 
 192. Goniobasis chrysaloidea White. Bear River Valley, near Mellis 
 Station, Wyoming. Described on a following page. 
 
 193. Goniobasis Cleburni White. Bear River Valley, near Mellis Sta- 
 tion, Wyoming 1 . Described on a following page. 
 
 1 94. Goniobasis f. Upper Kanab, Utah. It is associated with 
 
 Pyrgulifera humerosa Meek, and bears some resemblance to G. Cleburni, but 
 it has a proportionally much shorter spire. The specimens are all sand- 
 stone casts. 
 
 195. Pyrgulifera humerosa Meek. Bear River Valley, near Mellis Sta- 
 tion, Wyoming, and Upper Kanab, Utah. 
 
 196. Viviparus Panguitchensis White. Sevier Cliffs, twelve miles above 
 Panguitch, and Upper Kanab, Utah. 
 
 197. Campeloma macrospira Meek. Bear River Valley, near Mellis 
 
 
 
 Station, Wyoming, and Canon, of Desolation, Utah. 
 
 198. Odontobasis buccinoidea White. Two miles west of Point of Rocks, 
 Wyoming. Described on a following page. 
 
 199. Turritella ?. Upper Kanab, Utah. Near the base of the 
 
 group. 
 
 CRETACEOUS FOSSILS FROM BEYOND THE LIMITS OF THE PLATEAU 
 
 PROVINCE. 
 
 200. Ostrea congesta Conrad. Western Kansas, and near Platte Canon, 
 Middle Park, Colorado. 
 
 201. Ostrea - -I. Near Platte Canon, Middle Park, Colorado. A 
 large biconvex species. 
 
102 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 202. Ezogyra ponderosa Roemer. Near Platte Canon, Middle Park, 
 Colorado. 
 
 203. Inoceramus deformis Meek. Western Kansas. 
 
 204. Inoceramus ( Volviceramus) exogyroides Meek. Three miles north- 
 eastward from Hot Springs, Middle Park, Colorado. 
 
 205. Inoceramus BaraUni Morton ?. The specimens vary from the 
 typical forms in being deeper from hinge-line to base. 
 
 206. Avicula Parkensis White. South of Grand River, Middle Park, 
 Colorado. Described on a following page. 
 
 207. Heteroceras ?. Three miles northwestward from Hot 
 
 Springs, Middle Park, Colorado. The species is represented by a fragment 
 
 only. 
 
 CENOZOIC AGE. 
 
 TERTIARY PERIOD. 
 
 BITTER CREEK GROUP. 
 
 208. Ostrea Wyomingensis Meek. Point of Rocks, Black Buttes, and 
 Rock Spring, Wyoming. 
 
 209. Ostrea arcuatllis Meek. Black Buttes, Wyoming. 
 
 210. Anomia f. Black Buttes, Wyoming. 
 
 211. Unio proplieticus White. Black Buttes, Wyoming. Described on 
 a following page. 
 
 212. Unio petrinus White. Black Buttes, Wyoming. Described on a 
 following page. 
 
 213. Unio f. Black Buttes, Wyoming. A large massive species, 
 
 but much shorter than U. petrinus, with which it is associated. 
 
 214. Unio f. Near Evanston, Wyoming. A large, elongate 
 
 species, but the specimens are too imperfect for specific recognition or de- 
 scription. 
 
 215. Unio Leanus Meek! South Fork of Vermilion River, near Dia- 
 mond Peak, Northwestern Colorado. 
 
 216. Unio brachyopisthus White. Black Buttes, Wyoming. Described 
 on a following page. 
 
 217. Corbicula (Leptesthes) fracta Meek. Black Buttes, Wyoming. 
 
CATALOGUE OF FOSSILS. 103 
 
 218. Cyrena (Veloritina) Bannisteri Meek. Point of Rocks, Wyoming. 
 
 219. Pisidium saginatum White. Almy Coal Mines, near Evanston, 
 Wyoming. Described on a following page. 
 
 220. Corbula subwndata White. Point of Rocks, Wyoming. Described 
 on a following page. 
 
 221. Corbula crassitelliformis Meek. Black Buttes, Wyoming. 
 
 222. Planorbis Utahensis Meek. South base of Pine Valley Mountains, 
 Utah. (See No. 245, and also general remarks on page 85.) 
 
 223. Planorbis ?. Almy Coal Mines, near Evanston, Wyoming. 
 
 224. Planorbis (Bathyomplialus) f. Almy Coal Mines, near 
 
 Evanston, Wyoming. The specimens consist of fragments only, but they 
 indicate a large, well marked species of this subgenus. 
 
 225. Physa pleromatis White. Southeast flank of Quien Hornet Mount- 
 ain, Wyoming ; east base of Pine Valley Mountains, Utah, and many other 
 localities. 
 
 226. Physa 1. Almy Coal Mines, near Evanston, Wyoming. 
 
 227. Helix L Almy Coal Mines, near Evanston, Wyoming. 
 
 228. Helix- -?. Different from No. 227. East base of Pine Valley 
 Mountains, Utah. 
 
 229. Helix peripheries White. South base of 'Pine Valley Mountains, 
 Utah. Described on a following page. 
 
 230. Neritina volvilineata White. Black Buttes, Wyoming. Described 
 on a following page. 
 
 23 1 . Goniobasis tenera Hall sp. Various localities. (See Nos. 247, 259, 
 and 265, and also general remarks on page 85.) 
 
 232. Goniobasis ?. Almy Coal Mines, near Evanston,Wyoming. 
 
 This species is related to G. Ncbrascensis Meek and Hayden, but is more 
 elongate. 
 
 233. Goniobasis Wyomingcnsis Meek. Black Buttes, Wyoming. 
 
 234. Hydrobia recta White. Almy Coal Mines, near Evanston, Wyoming. 
 Described on a following page. 
 
 235. Hydrobia Utahensis White. West base of Mu-si-ni-a Plateau, 
 1,000 feet below its summit, Utah. 
 
104 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 236. Viviparus plicappressus White. Black Buttes, Wyoming. De- 
 scribed on a following 1 page. 
 
 237. Viviparus trocliiformis Meek. West base of Mu-si-ni-a Plateau, 
 tain, 1,000 feet below its summit. 
 
 238. Viviparus trochiformis var. Associated with No. 337. 
 
 239. Viviparus paludincBformis Hall sp. Various localities. (See Nos. 
 248, 260, and 266, and also general remarks on page 85.) 
 
 240. Tidotoma Tlwmpsoni White. Black Buttes, Wyoming. Described 
 on a following page. 
 
 241. Leioplaxf turricula White. Black Buttes, Wyoming. Described 
 on a following page. 
 
 LOWER GEEEN EIVER GROUP. 
 
 242. Unio Shoslionensis White. West side of Snake River, six miles 
 north of Junction Mountain ; cliffs four miles northwestward from the head 
 of Vermilion Canon and Dry Mountains, Northwestern Colorado. Described 
 on a following page. It occurs also in the Upper Green River Group. (Sec 
 No. 249.) 
 
 243. Unio ?, Two miles east of Lawrence Station, Wyoming. 
 
 Base of the group. 
 
 244. Spliarium f. Four miles northeastward from the head of 
 
 Vermilion Canon, Northwestern Colorado. 
 
 245. Planorbis Utaliensis Meek. West side of Snake River, six miles 
 north of Junction Mountain, Northwestern Colorado. It occurs also in the 
 Bitter Creek Group. (See No. 222, and also general remarks on page 85.) 
 
 246. Helix riparia White. Eight miles below Green River Station, 
 Wyoming. Described on a following page. 
 
 247. Goniobasis tenera Hall sp. Various localities. (See Nos. 231, 
 259, and 265, and also general remarks on page 85.) 
 
 248. Viviparus paludinceformis Hall sp. Various localities. (See Nos. 
 239, 260, and 266, and also general remarks on page 85.) 
 
 UPPER GREEN RIVER GROUP. 
 
 249. Unio Shoslionensis White. Henry's Fork and Alkali stage-sta- 
 
CATALOGUE OF FOSSILS. 105 
 
 tion, Wyoming-. Described on a following page. It occurs also in the 
 Lower Green River Group. (See No. 242.) 
 
 250. Unio ?. Henry's Fork, Wyoming. 
 
 251. SptwBrium ?. Alkali stage-station, twenty-one miles north- 
 ward from Green River Station, Wyoming. 
 
 252. Planorbis spectabilis Meek. Henry's Fork, Wyoming. Occurs 
 also in the Bridger Group. (See No. 263, and also general remarks on 
 page 85.) 
 
 253. Planorbis 1. Henry's Fork, Wyoming. A small species, 
 
 marked with fine revolving lines. 
 
 254. Pliysa ?. Henry's Fork, Wyoming. 
 
 255. Succinea papillispira White. Alkali stage-station, Wyoming. De- 
 scribed on a following page. 
 
 256. Helix f. Henry's Fork, Wyoming. A small species, 
 
 somewhat resembling the recent H. perspective 
 
 257. Piqm incolata White. Henry's Fork, Wyoming. Described on a 
 following page. 
 
 258. Pupa arenula White. Henry's Fork, Wyoming. Described on a 
 following page. 
 
 259. Goniobas-is tenem Hall sp.- Various localities. (See Nos. 231, 247, 
 and 265, and also general remarks on page 85.) 
 
 260. Viviparus paludinaformis Hall sp. Henry's Fork and Alkali stage- 
 station, Wyoming, and various other localities. At the first-named locality 
 the specimens are below the usual average size. (See Nos. 239, 248, and 
 266, and also general remarks on page 85.) 
 
 261. Cypris f. Henry's Fork, Wyoming. This species seems 
 
 to be specifically different from C. Leidyi Evans and Shumard. 
 
 BRIDGES GROUP. 
 
 262. Unio Haydeni Meek. Near Fort Bridger, Wyoming. 
 
 263. Planorbis spectabilis Meek. Henry's Fork, east of Fort Bridger, 
 and six miles west of Badland Mountains, Wyoming. Occurs also in the 
 Upper Green River Group. (See No. 252, and also general remarks on 
 page 85.) 
 
106 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 264. Pliysa Bridgerensis Meek. Henry's Fork, east of Fort Bridger, 
 Wyoming. 
 
 265. Goniobasis tenera Hall sp. Various localities. (See Nos. 231, 
 247, and 259, and also general remarks on page 85.) 
 
 - 266. Viviparus paludinceformis Hall sp. Various localities. (See Nos. 
 239, 248, and 260, and also general remarks on page 85.) 
 
 267. Viviparus Wyomingensis Meek. Near Fort Bridger, and six miles 
 west of the Cameo Mountains, Wyoming. This seems to be specifically dis- 
 tinct from the prevailing form that I have referred to V. paludinceformis, 
 being a larger, thinner, and more inflated shell. 
 
 BROWN'S PAKK GKOUP. 
 
 268. Physa ?. This is the only invertebrate species discovered 
 
 in the strata of this group, 'and all the examples of it are too imperfect to 
 serve as the basis of a specific description. 
 
 TERTIARY FOSSILS FROM BEYOND THE LIMITS OF TIIE PLATEAU 
 
 PROVINCE. 
 
 269. Flustra f. Bijou Basin, forty miles east of Denver, Colo- 
 rado. The specimens are found incrusting the oyster, No. 270. 
 
 270. Ostrea f. Bijou Basin, forty miles east of Denver, Colo- 
 rado. The species is a very large one ; the largest example is nearly a 
 foot in length and proportionally broad. 
 
 271. Cyrena ( Veloritina) f. Fresh-water Tertiary deposits, Crow 
 
 Creek, Colorado, where it was- found associated with No. 278. 
 
 272. Corbicula Powetti White. Bijou Basin, forty miles east of Denver, 
 Colorado. Described on a following page. 
 
 273. Venus f. Bijou Basin, forty miles east of Denver, Colo- 
 rado. The specimens are fragmentary, but the hinge is shown. 
 
 274. Petricola f. Burrows only. Bijou Basin, Colorado. 
 
 275. Mesodesma Bishopi White. Bijou Basin, forty miles east of Den- 
 ver, Colorado. Described on a following page. 
 
 276. Dentalmm f. Bijou Basin, Colorado. A small longitudi- 
 nally striated species. 
 
DESCRIPTIONS OF NEW SPECIES. 107 
 
 277. Dentalium f. Bijou Basin, Colorado. Much like No. 276, 
 
 except that its surface is marked only by encircling lines of growth. 
 
 278. Melania Larunda White. Crow Creek, Colorado, where it is 
 associated with No. 271. Described on a following page. 
 
 279. Patella f. Bijou Basin, Colorado. A single small exam- 
 ple. 
 
 280. Phorus exoneratus White. Bijou Basin, Colorado, forty miles east 
 of Denver, Colorado. Described on a following page. 
 
 281. Cerithium f. Bijou Basin, Colorado. A single, small, 
 
 imperfect example. 
 
 t 
 
 DESCRIPTIONS OF NEW SPECIES OF INVERTEBRATE FOS- 
 SILS FROM STRATA OF THE CARBONIFEROUS, JURASSIC, 
 CRETACEOUS, AND TERTIARY PERIODS. 
 
 CARBONIFEROUS PEKIOD. 
 Radiata. 
 Actinozoa. 
 
 Genus AMPLEXUS Sowerby. 
 
 Amplexus zaphrentiformis (sp. nov.). Corallum having the external aspect 
 of Zaplirentis rather than of Amplexus, being elongate-conical in form, more 
 or less curved and tapering to a point or small pedicil at the base; epitheca 
 well developed, having its surface marked by the usual concentric wrinkles 
 and lines of growth, and with longitudinal lines marking the position of the 
 septa, the latter not being very distinct; calyx circular or subcircular, the 
 plain portion of the surface at its bottom equal to one-third or more of the 
 diameter of the corallum ; septal fossette well developed, situated at the con- 
 cave side of the corallum; septa thirty or forty in number, rather strong; 
 transverse plates numerous, well developed, somewhat irregular, and ending 
 exteriorly against a moderately well developed external wall, which is dis- 
 tinct from the epitheca proper. This external wall contains no vesicles and 
 apparently consists of solid coralline substance. 
 
108 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 The largest- example in the collection is nearly nine centimeters in 
 length, the calyx having a diameter of twenty-five millimeters; but the 
 average size of nearly one hundred examples is considerably less. 
 
 This species differs from all other species of Amplexus known to me in 
 its zaphrentoid form, but its plain calyx-bottom, its broad transverse plates, 
 and the absence of a vesicular zone, leave no doubt as to the propriety of 
 referring it to the genus Amplexus. 
 
 Position and locality. Lower Aubrey Group; Split Mountain Canon, and 
 near Echo Park, Utah. 
 
 Echinodermata. 
 
 Genus EUPACHYCRINUS Meek and Worthen. 
 
 
 
 Eupachycrinus platybasis (sp. nov.). Calyx nearly flat; basal pieces 
 small, concealed by the first joint of the column, which is proportionally 
 large ; subradial pieces rather small or of medium size, their inner ends also 
 covered by the first joint of the column; judging from the portion of them 
 that is visible, they are all of nearly regular rhombic outline; first radials 
 much broader than long, broadly convex from side to side and abruptly 
 convex from within, outward, all of them ending with a regular obtuse angle 
 between the subradial pieces except the left anterior one, the angle of which 
 is made a little irregular by the interposition of the second anal plate ; first 
 anal piece of the same size and shape as the subradial pieces; second anal 
 piece apparently nearly as large as the first, between which and the left 
 anterior first radial piece it is interposed, reaching nearly as far inward as 
 the first radial piece does, and at which point it ends with an acute angle; 
 plates all massive. Remainder of the structure unknown. Sutures all linear > 
 surface nearly or quite smooth. 
 
 Diameter of the calyx, eighteen millimeters. 
 
 This species differs from the typical forms of the genus in the extreme 
 flatness of its calyx, but the arrangement, number, and general character of 
 the pieces composing it leave no doubt as to the propriety of referring it to 
 Eupacliycrinus. 
 
 Position and locality. Lower Aubrey Group; confluence of Grand and 
 Green Rivers, Utah. 
 
DESCRIPTIONS OF NEW SPECIES. 109 
 
 Genus ARCILEOCIDARIS McCoy. 
 
 Arcliceocidaris cratis (sp. nov.). Spines slender, gradually tapering from 
 base to point; shaft ornamented with sharp, distant spinules, each about one 
 and a half millimeters long and pointing strongly upward ; basal ring promi- 
 nent, plain, except the fine crenulation of its edges, and situated very near 
 the proximal end of the spine. Surface apparently smooth. 
 
 Length about six centimeters; diameter just above the basal ring 1 nearly 
 three millimeters; diameter of basal ring about four millimeters. 
 
 The collections of the Geological Survey of Nebraska in the cabinet 
 of the Smithsonian Institution contain a single spine of this species, which, 
 together with that of these collections, is all that is known of the species. 
 It may be readily recognized by its smooth, slender shaft, with its distant, 
 sharp spinules. 
 
 Position and locality. Lower Aubrey Group; confluence of the Grand 
 and Green Rivers, Utah. 
 
 Mollusca. 
 
 Gasteropoda. 
 
 Genus ^NATICOPSIS McCoy. 
 
 Naticopsis remex (sp. nov.). Shell of ordinary size, very oblique when 
 adult, by the elongation and enlargement of the last volution ; volutions 
 about four, convex, increasing rapidly in size, the last one large and much 
 produced ; spire small and short ; suture impressed. Surface marked by 
 the usual lines of growth, and, although that of the specimens in the collec- 
 tion is not very well preserved, there are some indications of the presence 
 of faint revolving striae also. 
 
 Length across the longest diameter of the aperture and body volution 
 of an average-sized specimen, twenty-three millimeters ; short diameter of 
 the same, seventeen millimeters. 
 
 Position and locality. Summit of the Lower Aubrey Group ; confluence 
 of the Grand and Green Rivers, Utah. 
 
110 INVERTEBltATE PALEONTOLOGY. [WHITE. 
 
 JURASSIC PERIOD. 
 
 Mollusca. 
 
 Conchifera. 
 
 Genus UNIO Retzius. 
 
 Unio Stewardi (sp. nov.). From the Jurassic strata at Flaming Gorge 
 of Green River, near the northern boundary line of Utah, some portions of 
 a moderately large Unio were obtained that belong to an undescribed 
 species. The valves are broadly oval in marginal outline, broadly but 
 somewhat uniformly convex ; beaks very near the anterior end ; test 
 massive ; surface apparently marked only by the ordinary lines and imbri- 
 cations of growth ; cardinal and lateral teeth both strong ; the lower lateral 
 tooth of the left valve, and also that part of the hinge of the right valve 
 against which it shuts, both strong and rounded into the cavity of each 
 valve respectively, and both ^nd posteriorly by abruptly rounded ends. 
 
 Length of largest example, eight and. a half centimeters ; height, sixty- 
 two millimeters. 
 
 Compared with U. nucalis Meek and Hayden, the only other species 
 of the genus known to me from American Jurassic strata, it is larger, more 
 massive, the beaks placed more anteriorly, and the cardinal and lateral 
 teeth more massive. 
 
 Specific name given in honor of Mr. J. F. Steward, of Piano, 111., its 
 discoverer. 
 
 Gasteropoda. 
 
 Genus NERITINA Lamarck. 
 
 Neritini ? ? Powelli (sp. nov.). Shell moderately large, obliquely sub- 
 ovate in outline ; volutions about three or three and a half, rapidly increas- 
 ing in size, the last one much expanded ; spire depressed, the apex scarcely 
 appearing by side view of the shell ; suture slightly impressed ; aperture 
 large, broadly subcircular or subtetrahedral ; a broad rounded revolving 
 prominence extends around the volutions, nearer to their distal than prox- 
 imal side, and another less prominent one between the first one and the 
 suture ; the first one, especially, gives a degree of angularity to the last 
 volution and to the margin of the aperture. 
 
DESCRIPTIONS OF NEW SPECIES. HI 
 
 Surface marked by ordinary lines of growth, and also by somewhat 
 prominent folds parallel with them; the folds being stronger upon the 
 revolving prominences before mentioned than elsewhere, and disappear 
 upon the under surface of the shell. 
 
 Greatest diameter of the largest example, twenty-eight millimeters ; 
 breadth of the same, twenty millimeters ; height, the aperture resting upon 
 the table, fifteen millimeters. 
 
 By carefully digging out the stony filling I have been unable to find 
 any trace of a thickened inner lip such as characterizes the Neritidse, but 
 the body seems to be small, simple, and without even a proper columella. 
 The shell has the external aspect of a member of the family Neritidae, but 
 it is not without much hesitation that I refer it to the genus Neritina. 
 Indeed, this reference of it is made only provisionally until further investi- 
 gation can be made. This disposition of it is made partly because it seems 
 properly referable to no other established genus, and partly in view of the 
 facts published by Brinkhorst in his Monog. Gast. et Ceph. de la Craie Sup. 
 du Limbourg, 1861. In that work he describes and figures two species, 
 Nerita rugosa Hoeninghaus, and N. parvula Brink., which he shows to have 
 been so fossilized that the callus which formed the thickened inner lip was 
 entirely removed by a natural process of solution, leaving the remainder of 
 the shell intact, and in a condition similar to that of the species here 
 described as regards the absence of an inner lip, but natural casts of his 
 species showed that they originally possessed a well developed one. No 
 such casts have been found with our shells, and it is not improbable that 
 they were originally without any thickened inner lip. 
 
 If so, our shell cannot be properly referred to any genus with which I 
 am acquainted, arid in case further investigation shall leave no doubt that 
 the shells have not been changed from their original character, I propose for 
 it the generic name of Lyosoma. 
 
 Specific name given in honor of Prof. J. W. Powell, geologist in charge 
 of the Second Division United States Geological and Geographical Survey. 
 
 Position and locality. Flaming Gorge Group; mouth of Thistle Creek, 
 Spanish Fork Canon, Utah. 
 
112 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 CRETACEOUS PERIOD. 
 Mollusca. 
 
 Conchifera. 
 
 Genus OSTREA Linnaeus. 
 Subgenus ALECTEYONIA Fischer. 
 
 Ostrea (Alectryonia) sannionis (sp. nov.). Shell rather small, alate at 
 both sides of the beak, irregularly subquadrate in marginal outline, its 
 longitudinal axis curved, the convexity -of the curve being forward, almost 
 as wide across the alations as at the base, but constricted in the middle ; 
 beaks small, not prominent, directed slightly backward ; lower valve mod- 
 erately convex ; scar of attachment at the beak small or. absent ; ligament- 
 area short, rather broad ; its longitudinal furrow shallow but well defined, 
 transversely striated, and pointing obliquely backward ; posterigr alation 
 narrower than the anterior one, and a little longer than the corresponding 
 alation of the other valve ; muscular scar comparatively large, situated 
 nearly mid-length of the valve and near the posterior margin, curved- 
 spatulate in outline, the broadest end being toward the base of the shell ; 
 upper valve nearly flat, but in other respects corresponding with the lower. 
 
 Surface of both valves marked by the ordinary lines and lamellatioris 
 of growth common to the genus and by numerous creiiulated radiating pli- 
 cations, four or five of which upon each valve reach the base of the shell, 
 giving that margin a coarsely zigzag or toothed condition. The other pli- 
 cations are smaller and die out at the sides of the shell and upon the alations. 
 
 Length from base to beak of a large example thirty-eight millimeters ; 
 breadth near the front the same; across the wings, thirty- three millimeters. 
 
 This is one of the most distinctly defined species of the genus known 
 to me, and numerous examples of it show that it was subject to compara- 
 tively little variation. 
 
 . Position and locality. Near top of Salt Wells Group ; Weber Valley, 
 near Coalville, Utah. 
 
 Ostrea insecura (sp. nov.). Shell rather small, thin, elongate-suboval 
 in outline when adult, suboval or snbcircular when young ; beaks and area 
 
DESCRIPTIONS OF NEW SPECIES. J 13 
 
 small; scar of attachment usually small and sometimes absent; surface com- 
 paratively smooth for an oyster ; a few faint radiating plications appearing 
 upon some examples. Length of largest example nearly five and a half 
 centimeters ; breadth twenty-nine millimeters. 
 
 Position and locality. Point of Rocks Group; two miles west of Point 
 of Rocks, Wyoming. 
 
 Genus PLICATULA Lamarck. 
 
 Plicatida liydrotlieca (sp. nov.). Shell of ordinary size, irregularly sub- 
 ovate in marginal outline; beaks rather narrow ; lower valve broadly con- 
 vex ; hinge teeth well developed ; upper valve nearly flat, or slightly 
 concave near the beak. 
 
 Surface of both valves marked by small, slightly raised radiating 
 plications, which are crenulated, a little irregular and more or less distinct 
 upon all parts of the surface of both valves. 
 
 Length, three centimeters ; greatest breath, twenty-four millimeters. 
 
 Position and locality. Henry's Fork Group; head of Water-pocket 
 Canon, Southern Utah. 
 
 Genus INOCERAMUS Sowerby. 
 
 Inoceramus Gilberti (sp. nov.). Shell irregularly suboval in marginal 
 outline, the transverse diameter being greater than the vertical; front flat- 
 tened; valves nearly or quite equal, both being gibbous and sometimes quite 
 ventricose; umbones broad and elevated; beaks very near the front, incurved 
 but not projecting beyond the front margin ; front nearly straight vertically, 
 and forming nearly a right angle with the hinge; front margin rounded 
 below to the basal margin, which is broadly convex for more than half the 
 length of the shell; postero-basal margin extending obliquely upward, with 
 a slight emargination to the posterior extremity, which is abruptly rounded 
 to meet the downward-sloping postero-dorsal margin; dorsal margin straight, 
 its length equaling more than half the long diameter of the shell. 
 
 Upon each valve there is an obscure radiating shallow furrow or de- 
 pression extending from the umbonal region to the postero'-basal border and 
 
 ending at the emargination there, before mentioned. 
 SPG 
 
114 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 Surface marked by the usual lines of growth, and also by numerous 
 extravagant and irregular concentric folds or wrinkles. 
 
 This species belongs to the section of the genus that Brongniart has 
 designated under the name of Catillus. It is a peculiarly well-marked species 
 and easily distinguished from all others found in the rocks of the great 
 Rocky Mountain region. 
 
 Transverse length of an average-sized specimen seven and a half centi- 
 meters; height from base to hinge, five centimeters. Specific name given 
 in honor of its discoverer, Mr. G. K. Gilbert, geologist of one of the survey- 
 ing parties. 
 
 Position and locality. Salt Wells Group; near Last Chance Creek, 
 Southern Utah. 
 
 Inoceramus Howelli (sp. nov.). Shell of medium size, obliquely and 
 irregularly suboval in marginal outline, the vertical diameter being greater 
 than the transverse; both valves having considerable convexity, that of the 
 left valve greater than the other; beaks narrowed, prominent, the prominence 
 of the left one greater than the other, both of them elevated above the 
 hinge line, and also curving forward beyond the front of the shell; front 
 flattened, extending almost straight downward from the front end of the 
 hinge, with which it forms nearly a right, or slightly obtuse, ang-le. Antero- 
 basal margin abruptly rounded to. the base; basal margin short; postero- 
 basal margin extending obliquely upward to the posterior extremity, straight- 
 ened or slightly emarginate; posterior extremity abruptly rounded to meet 
 the almost straight postero-dorsal margin. 
 
 Between the axis of the body of the shell and the postero-dorsal margin 
 there is upon each valve a rather broad, shallow, but more or les*s distinct 
 furrow or depression, extending from the umbonal region to the postero- 
 basal margin, and ending at the emargination before mentioned. There is 
 also a distinct alation upon each valve, separated from the body portion by 
 a tolerably well-defined auricular furrow. 
 
 Surface marked by the ordinary lines of growth, and also by moder- 
 ately distinct concentric folds, but the surface has a rather smoother aspect 
 than is usual with species of this genus. Height of an average-sized example, 
 
DESCRIPTIONS OF NEW SPECIES. 115 
 
 from base to beaks, seven and a half centimeters; greatest breadth, which 
 is near the base, five centimeters; length. of hinge, thirty-seven millimeters. 
 
 This shell somewhat resembles I. fragllls Hall and Meek, but differs 
 from it in possessing the shallow radiating furrow upon the body of the 
 valve, and also in having a distinct posterior ear, separated from the body 
 of the valve by an auricular furrow. It also resembles an example of /. 
 striatus Mantell, in the cabinet of the Smithsonian Institution, from Saxony, 
 but the beaks of our species are more elevated and turned more forward 
 than they are in that species. I. striatus is also without the shallow radiat- 
 ing furrow before mentioned. It differs from I. flaccidus White in its smaller 
 size, its smoother surface and more gibbous valves, that species being coarsely 
 and extravagantly wrinkled. Specific name given in honor of Mr. E. E. 
 Howell, who discovered it while geologist of one of the surveying parties. 
 
 Position and locality. Henry's Fork Group; Lower Potato Valley and 
 Upper Pine Creek, Utah. 
 
 Genus AVIOULA Klein. 
 
 Avicida Parkensis (sp. nov.). Shell small, slightly inequivalve, very 
 oblique, elongate, thin at all the margins except the cardinal; anterior wing 
 of ordinary size and shape; posterior wing rather large arid long; both 
 valves broadly but regularly convex; body of the shell broadest behind the 
 middle; antero-basal border broadly convex; posterior extremity regularly 
 rounded; postero-dorsal border nearly straight from the posterior border to 
 the base of the posterior wing; beaks of ordinary prominence; surface ap- 
 parently smooth. 
 
 Length from the end of the anterior wing to the posterior extremity of 
 the shell, thirty-four millimeters; breadth across the widest part of the body, 
 fifteen millimeters. 
 
 This species resembles A. lingulifera Shumard, but differs from that 
 species in its more elongate form and more oblique hinge line. 
 
 Position and locality, Cretaceous strata; south of Grand River, Middle 
 Park, Colorado. 
 
 Genus ARCA Linna3us. 
 
 Area? Coalvillensis (sp.nov.). Shell longer than high, moderately thick; 
 test somewhat massive; beaks depressed, situated near the anterior end; 
 
116 INVERTEBRATE PALEONTOLOGY. [WHITR. 
 
 umbones broad; anterior end rounded or subtrimcate; base nearly straight 
 or very broadly convex, and often slightly emarginate about the middle; 
 postero-basal border rounded upward to the posterior extremity, which is 
 abruptly rounded to the downward sloping, nearly straight postero-dorsal 
 border, the latter forming an obtuse angle with the hinge border; hinge 
 equal in height to about two-thirds the entire length of the shell. 
 
 A slight depression or flattening extends from the umbo of each valve 
 to its base, causing the straightening or slight emargination of the basal 
 border before mentioned. Area nearly obsolete ; hinge rather slender; two 
 or three long, slender transverse teeth occupy its middle portion; seven or 
 eight teeth cross the surface of its posterior end obliquely downward and 
 inward, and about an equal number of smaller ones cross the anterior end 
 almost vertically; the inner ones of the latter set of teeth being very small 
 and situated nearly beneath the beaks. 
 
 Surface marked by ordinary lines of growth, and by fine radiating 
 lines, which are often obscure. Length, five centimeters; height, thirty- 
 three millimeters. 
 
 Position and locality. Salt Wells Group; Coalville, Utah 
 
 Genus UNIO Retzius. 
 
 Unio yonionotus (sp. nov.). Shell elongate-subelliptical in marginal out- 
 line; flattened and thin when young, but becoming gibbous or almost cylin- 
 drical with age; dorsal margin broadly convex; base nearly straight; front 
 regularly rounded; the rounding of the posterior end somewhat irregular, 
 in consequence of the plications of the valves at that part; beaks obsolete, 
 the umbonal region of each valve so flattened that they form an acute angle 
 at the dorsum in the young, the angle increasing with age, so that it is very 
 obtuse in the adult shell. 
 
 Surface of the anterior portion of the shell marked by only the ordi- 
 nary lines and lamellations of growth, but the posterior portion, comprising 
 more than half the length, is marked by strong, more or less irregularly 
 radiating plications, which begin faintly a little forward of the middle, and 
 increase gradually in strength to the posterior and postero-basal margins, 
 and increase in number by a few bifurcations toward those margins; curv- 
 
DESCRIPTIONS OF NEW SPECIES. 
 
 ing upward and backward from the uppermost of the longer plications there 
 are several smaller, short ones that end at the postero-dorsal margin. 
 
 Length of the largest example in the collection, sixty -three millimeters; 
 height, thirty-five millimeters. Young examples have very different propor- 
 tions, as well as a marginal outline of different shape. 
 
 This species differs conspicuously from any other fossil Unio known to 
 me, although young examples of it have some resemblance to those of the 
 recent species U. multiplicatus, but the adult specimens have a very different 
 aspect. It differs from U: belliplicatus Meek, from equivalent strata in South- 
 western Wyoming, in its general shape and in the position and distribution 
 of the plications, they being most conspicuous on the anterior portion of 
 that shell, while the corresponding portion of ours is plain. 
 
 Position and locality. Point of Rocks Group; Upper Kanab, Utah. 
 
 Genus CYRENA Lamarck. 
 Subgenus VELOKITINA Meek. 
 
 Cyrena (Vdoritina) erecta (sp. nov.). Shell of medium size, subovate 
 in marginal outline when adult, but subcircular when young, gibbous, espe- 
 cially the upper median portion, but somewhat compressed laterally at the 
 postero-basal portion; front and basal margins regularly and continuously 
 rounded; postero-basal extremity somewhat abruptly rounded upward to 
 the sloping, broadly rounded postero-dorsal margin; umbones elevated; 
 beaks small, incurved, and pointing forward; postero-dorsal margin of each 
 valve flexed strongly inward, so that the hinge-ligament is hidden from 
 sight by side view of the shell. 
 
 Surface marked by the ordinary lines of growth. 
 
 Length, thirty millimeters; height from base to umbones, thirty-four 
 millimeters. 
 
 Position and locality. Salt Wells Group; Upper Kanab, Utah, and Ilil- 
 liard Station, Wyoming. 
 
 Genus TURNUS Gabb. 
 
 Turnus sphenoideus (sp. nov.). Shell elongate-cuneate, inflated in front, 
 narrowed, and laterally flattened behind; beaks anterior, incurved, adjacent; 
 
118 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 postero- dorsal margin sloping from behind the beaks to the posterior ex- 
 tremity, and apparently capped by a slender, accessory plate; posterior 
 extremity abruptly rounded; basal margin nearly straight; front regularly 
 rounded, both laterally and vertically; anterior gape consisting of a narrow, 
 vertical slit that occupies the middle of a somewhat prominent projection at 
 the antero-basal portion of the shell, which projection has the shape of a 
 Norman shield, as seen by front view, when both valves are in their natural 
 position i umbonal groove distinct and moderately deep, causing a distinct 
 groove upon the stony internal casts of the shell, which is of about the' 
 same dimensions and character as that which is left by the radiating internal 
 rib ; besides these two grooves, there is another, somewhat broader furrow 
 radiating from behind the beak of each valve to near the posterior end. A 
 broad, cake-like accessory plate covers the beaks and the space between 
 them; and, apparently, two others, one upon each valve, occupy the space 
 between the umbonal plates and the top of the Norman shield-shaped pro- 
 jection before mentioned. 
 
 Surface marked by fine, concentric, raised lines, besides the radiating 
 furrows before mentioned. The masses of rock from which our specimens 
 were broken out, contained what appear to have been calcareous, siphonal 
 tubes, but none of them were found to be unmistakably connected with the 
 shells. 
 
 Length, thirteen millimeters ; greatest height, seven millimeters ; breadth 
 at the front, six millimeters. 
 
 Position and locality. Sulphur Creek Group; Upper Kanab, Utah. 
 
 Gasteropoda. 
 
 Genus RHYTOPHORUS Meek. 
 
 Rliytoplionis Mcckii (sp. nov.). Shell subfusiform; spire moderately pro- 
 duced, nearly one-third as long as the entire length of the shell ; volutions 
 about six, convex, the last one somewhat large, elongate, convex, and taper- 
 ing from the middle toward the anterior end ; suture impressed, and upon 
 the proximal side of it there is an almost equally impressed revolving line, 
 having the aspect of a second suture ; folds of the eolumella well developed. 
 
 Surface marked by the ordinary lines of growth and also upon the 
 
DESCRIPTIONS OF NEW SPECIES. H9 
 
 spire by numerous small longitudinal folds, parallel with the slightly 
 oblique direction of the lines of growth. These folds appear upon the distal 
 portion only of the last volution. 
 
 Length of the largest example obtained, twenty-five millimeters; diam- 
 eter of the body volution, twelve millimeters. 
 
 This species differs from R. priscus Meek, with which it is associated 
 in the less robust and more elongate form of the shell, its proportionally 
 longer spire, niore delicate and finer markings, and the less abrupt convexity 
 of the volutions upon the proximal side of the suture. 
 
 The specific name is given in honor of the author of the genus. 
 
 Position and locality. Point of Rocks Group ; Bear River Valley, near 
 Mellis Station, Wyoming. 
 
 Genus PLANORBIS Guettard. 
 Subgenus BATHYOMPHALUS Agassiz. 
 
 Planorlls (BatUyomplialus) Kanabensis (sp. nov.). Shell rather small ; 
 spire flat or nearly so, suture impressed ; volutions five or six, narrow, 
 regularly increasing in size to the aperture, broadly convex upon the upper 
 side ; periphery abrubtly rounded to the broadly convex under side, the 
 latter extending obliquely downward and inward to the well defined, mod- 
 erately broad, and deep umbilicus. 
 
 Surface marked by ordinary lines of growth. 
 
 Diameter of coil, twelve millimeters. 
 
 Position and locality. Point of Rocks Group; Upper Kanab, Utah. 
 
 Genus PHYSA Draparnaud. 
 
 PJiysa Kanabensis (sp. nov.). Shell rather under the average size; very 
 elongate ; spire extended ; volutions about six, broadly convex ; aperture 
 very narrow, ending sharply at its distal end and abruptly rounded at the 
 proximal end. 
 
 The specimens of the collection are all imperfect, but the species is 
 peculiarly distinguished by its very slender elongate form, its extended spire, 
 spire, and its very narrow elongate aperture. 
 
 Position and locality. Point of Rocks Group ; Upper Kanab, Utah. 
 
120 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 Genus HELIX Linnaeus. 
 
 Helix Kanabensis (sp. nov.). Shell having the general external shape 
 and character of H. palliata Say, but, besides being considerably smaller, it 
 presents some differences in its aperture. Like that species, its lip is re- 
 flexed, and it has a similar large tooth upon its parietal wall. In addition 
 to the latter there are four short linear ridges upon the inner surface just 
 within the upper and outer portion of the aperture, at the margin of which 
 they terminate exteriorly, but extend inward in the direction of the whorl 
 from two to three millimeters. The lowermost of these small ridges is 
 shortest, but more prominent and tooth-like than the others. Only a single 
 specimen was obtained, and that is very imperfect. It is described and 
 named here because of its value as showing the great differentiation of 
 Helecine types 30 early AS the Cretaceous period. 
 
 Position and locality. Point of Rocks Group; Upper Kanab, Utah. 
 
 Genus ANCHURA Conrad. 
 
 Anclmra ruida (sp. nov.). Shell rather small ; spire moderately elon- 
 gate ; volutions about seven, convex ; suture impressed ; wing moderately 
 large, contorted, bearing at its extero-posterior corner a falciform process 
 which points backward in the direction of the spire ; the outer border of 
 this process and also that of the body of the wing continuously and broadly 
 rounded to the extero-anterior corner of the wing, which is abruptly 
 rounded ; thence the anterior border of the wing extends nearly straight 
 inward to a somewhat broad curved sinus adjacent to the columella, which 
 sinus corresponds to the anterior canal in other species; inner border of the 
 falciform process broadly concave ; and between that process and the spire 
 the distal border of the wing is shortly concave and a little reflexed, sug- 
 gestive of a broad posterior canal, especially as the anterror canal is more 
 than usually broad; inner lip provided with a distinct callus, which in some 
 cases at least extends beyond the distal end of the aperture across the next 
 volution ; columella not much produced in front ; volutions of the spire 
 marked by many longitudinally oblique folds, which extend to the suture 
 on the proximal side of the volutions, but not much beyond the middle on 
 the distal side, and do not appear at all on the body volution or wing. 
 
DESCRIPTIONS OF NEW SPECIES. 121 
 
 The whole surface marked by fine revolving striae, which are more 
 distinct upon the last volution and wing ; last volution also marked by a 
 moderately strong revolving carina, which extends outward upon the wing 
 and is continued to the point of the falciform process. 
 
 Length, sixteen millimeters; breadth across the body volution, includ- 
 ing the wing, twelve millimeters. 
 
 This species resembles A. Americana Meek and Hay den. in general 
 form and surface markings, but it differs from that shell by its large anterior 
 sinus, the inflection of the anterior border, and the reflexion of the posterior 
 border of the wing, and also in the general shape of the wing. 
 
 Position and locality. Sulphur Creek Group; Upper Kanab, Utah. 
 
 Ancliura prolabiata (sp. nov.). Shell rather above medium size, sub- 
 fusiform ; spire elongated and tapering, with nearly straight sides, to a 
 point ; volutions, nine or ten, convex, the last one proportionally more en- 
 larged than the others ; suture impressed ; wing large, broad, its outer 
 border nearly straight or slightly convex, its anterior and posterior corners 
 abruptly rounded ; posterior border bearing a strong, broad, blunt process 
 about midway between the spire and the outer margin of the wing, the 
 outer margin of the process having a direction parallel with that of the 
 outer margin of the wing ; posterior border of the wing concave between 
 the outer corner and the base of the process, and also regularly and con- 
 tinuously concave from the spire to the end of the process ; anterior border 
 of the wing broadly and regularly concave to the base of the anterior canal, 
 which is apparently rather short. 
 
 Inner lip unknown. 
 
 Surface of the volutions of the spire marked by numerous vertical or 
 slightly oblique folds or ridges, which disappear upon the body volution 
 and wing ; these folds are crossed by numerous fine revolving raised lines, 
 which are hardly visible without the aid of a lens, except those adjacent to 
 the sutures, which are stronger ; these revolving lines are perceptible upon 
 the body volution, but are very faint upon the wing. No revolving ridge 
 passes out upon the wing from the body volution, such as is common upon 
 shells of this genus. 
 
 Length about four and a half centimeters ; breadth, measured across 
 
122 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 the wing and body volution, twenty-nine millimeters; diameter of the body 
 volution, fifteen millimeters. 
 
 This species differs from all others known to me by the projection of. 
 the outer border of the wing beyond the posterior process. 
 
 Position and locality. Sulphur Creek Group; Upper Kanab and Sink 
 
 Spring, Utah. 
 
 Genus LUNATIA Gray. 
 
 Lunatia Utahensis (sp. nov.). Shell globose ; spire small, acute, but 
 not much extended ; volutions about eight, the last one much inflated, 
 suture moderately impressed ; aperture semilunar, somewhat abruptly 
 rounded anteriorly, callus of the inner lip apparently not much thickened, 
 but thicker anteriorly than posteriorly. Surface marked by the ordinary 
 lines of growth. 
 
 Length from the apex to the anterior end of the aperture about four 
 centimeters; diameter about three centimeters. 
 
 Position and locality. Salt Wells Group; Coalville, Utah. 
 
 Genus GONIOBASIS Lea. 
 
 Goniobasis Clelurni (sp. nov.). Shell large, gradually tapering from the 
 last volution to the apex, the sides of the spire being only slightly convex; 
 volutions apparently nine or ten, gradually increasing in size, .the last one 
 not being proportionally larger than the others; suture slightly impressed; 
 sides of the volutions nearly flat or slightly convex, the outer and anterior 
 sides of the last one broadly and regularly convex; aperture ovate; outer 
 lip broadly sinuate. 
 
 Surface of the spire marked by strong longitudinal or slightly flexed and 
 oblique ridges or folds which disappear toward the aperture of the last volu- 
 tion. Upon the anterior surface of the last volution beyond the distal end 
 of the aperture, there are several slightly raised revolving lines, and the 
 edges of the vertical plications are also sometimes seen to be faintly crerm- 
 lated as if by incipient revolving lines. 
 
 The specimens of the collection have all lost the apex, but the length 
 of a full grown one is estimated at five centimeters; diameter of the last 
 volution, nineteen millimeters. 
 
DESCRIPTIONS OF NEW SPECIES. 123 
 
 This is the largest species of Goniobasis known to occur at the locality 
 where it was found, and which has furnished three other distinct species. 
 
 The specific name is given in honor of Mr. W. Cleburn, division en- 
 gineer of the Union Pacific Railroad. 
 
 Position and locality. Point of Rocks Group; Bear River Valley, near 
 Mellis Station, Wyoming. 
 
 Goniobasis clirysaloidea (sp. no v.). Shell of medium size, gradually taper- 
 ing from the last volution to the apex; volutions about seven or eight, those 
 of the spire slightly convex, the last one broadly rounded to the anterior 
 end; suture impressed, the apparent impression being increased by the pro- 
 jecting fold of the distal edge of each volution, which is appressed against 
 the proximal edge of the next preceding one. 
 
 Surface marked by more or less distinct longitudinal, slightly bent folds, 
 which are crossed by several revolving lines that appear only upon the folds 
 and not between them, giving them a knotted or crenulated appearance; 
 anterior surface of the last \olution also marked by distinct raised revolving 
 lines. 
 
 Length twenty-eight millimeters; diameter of the last volution, nine 
 
 O */ o 
 
 millimeters. 
 
 This species differs from G. chrysalis Meek in its much larger size, 
 much greater apical angle, straighter sides, and in the details of its ornamen- 
 tation. 
 
 Position and locality. Point of Rocks Group; Bear River Valley, near 
 Mellis Station, Wyoming. 
 
 Genus VIVIPARUS Montfort, 
 
 Viviparus Pangmtchensis (sp. nov.). Shell elongate-trochiform ; spire 
 considerably produced in the case of some of the examples, but less so in 
 others, convex-conical, diminishing more rapidly near the apex than at the 
 proximal half of the shell ; apex acute ; volutions about six, flattened upon 
 the outer side, especially the last two volutions; anterior side of the last 
 volution broadly rounded and forming a more or less distinct angle with the 
 outer side; the distal side of each volution concave to receive the convex 
 
124 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 proximal side of the next preceding one, but projects a little beyond it so 
 that an angular shoulder is formed upon the proximal side of the suture. 
 
 Aperture subtrihedral in outline. 
 
 Surface marked by the ordinary lines of growth, arid also by numerous 
 minute, raised revolving striae, upon both the outer and anterior sides of 
 the volutions. 
 
 There is considerable variation in the flattening of the outer side of the 
 volutions in different examples and in different parts of the same example. 
 The volutions near the apex of all the shells are usually convex and not 
 much if at all flattened ; in some cases the outer side of the last volution is 
 broadly convex, while in others it is not only flattened- but a little concave, 
 especially the part nearest the suture. 
 
 Length of an average sized example, thirty millimeters; diameter of 
 the last volution, twenty millimeters. 
 
 Genus ODONTOBASIS Meek. 
 
 Odontobasis buccinoidea (sp. nov.). Shell of medium size somewhat 
 robust; volutions six or seven, regularly convex; suture faintly impressed; 
 surface marked by somewhat strong longitudinal folds which end at the 
 suture upon the proximal side of the volutions of the spire, but do not quite 
 reach the suture upon the distal side, and upon the last volution they die 
 out before reaching the anterior end of the shell; the whole surface also 
 marked by somewhat coarse revolving raised lines, which in crossing the 
 longitudinal folds give them a crenulated appearance. The revolving lines 
 upon a narrow space on the proximal side of the suture, and also upon the 
 space in front of the revolving furrow of the columella, are finer than the 
 others. Odontoid process not very prominent, forming a small angular pro- 
 jection at the end of the revolving furrow of the columella. 
 
 Length, thirty-seven millimeters ; diameter of the last volution, twenty- 
 two millimeters; but these proportions vary considerably in different shells 
 of the species. 
 
 Position and locality. Point of Rocks Group; two miles west of Point of 
 Rocks, Wyoming. 
 
DESCRIPTIONS OF NEW SPECIES. 125 
 
 TERTIARY PERIOD. 
 Mollusca. 
 
 Conchifera. 
 
 Genus UNIO Retzius. 
 
 Uniopetrinus (sp. nov.). Shell very large, transversely elongate, moder- 
 ately thick; test massive; basal and dorsal margins subparallel; the latter 
 broadly but slightly convex and the former nearly straight or faintly emargi- 
 nate about, or a little behind the middle; front abruptly rounded; postero- 
 dorsal and postero-basal margins, somewhat abruptly rounded to the pos- 
 terior margin, giving, in some cases, a subtruncate appearance to the posterior 
 end of the shell; beaks depressed, situated near the anterior end; umbones 
 broad; hinge massive, both cardinal and lateral teeth being very strong. 
 
 Surface apparently marked in no other manner than by the ordinary 
 lines and imbrications of growth. The outer prismatic layer is well preserved, 
 and the umbones, like those of all the species of Unio I have examined, from 
 the Mesozoic and Cenozoic strata of that region, appear to have suffered, 
 while living, no erosion, such as is common in the case of the recent Unio- 
 nidae of the Mississippi and its tributaries. 
 
 Length of the largest example in the collection, fifteen centimeters ; 
 height of the same, seven and a half centimeters. In the case of young 
 examples the length is proportionally greater. 
 
 This species may be readily distinguished from all others at all likely 
 to be confounded with it by its great size, elongate form, and its subparallel 
 dorsal and ventral margins. 
 
 Position and locality. Bitter Creek Group; Black Buttes, Wyoming. 
 
 Unio proplieticus (sp. nov.). Shell small or of medium size, obliquely 
 subovate in marginal outline, moderately thick, the greatest thickness being 
 a little below the umbones; test rather thick; umbones prominent, directed 
 forward; beaks curved inward and forward, reaching as far as, or a little 
 farther than, the front of the shell; front broad, nearly perpendicular; front 
 margin slightly convex above, but abruptly rounded to the basal margin 
 below ; basal margin broadly rounded, or sometimes a little straightened at 
 
126 INVERTEBRATE PALEONTOLOGY. [WIIITR. 
 
 the middle; posterior extremity abruptly rounded; dorsal margin broadly 
 rounded obliquely downward to the posterior extremity ; the dorsum of each 
 valve elevated and its margin flexed inward and downward to the cardinal 
 ligament, so that the latter is hidden from sight by side view of the shell. 
 
 Surface marked by the ordinary lines of growth and by numerous fine 
 radiating striae, which appear also in the substance of exfoliated portions of 
 the test 
 
 Length, five centimeters; height from -base to umbones, thirty-seven 
 millimeters. 
 
 This species is of the type of U. clavus Lamarck, which it much resem- 
 bles in general aspect. It is so different from any other known species of 
 Unio in the Tertiary rocks of America that it cannot be mistaken for any 
 of them. 
 
 Position and locality. Bitter Creek Group; Black Buttes, Wyoming. 
 
 Unio bracliyopistlms (sp. nov.). Shell small or of medium size, some- 
 what gibbous, subcircular in marginal outline, the length and height being 
 about equal ; umbones broad, not prominent ; beaks depressed, situated 
 near the middle of the dorsum ; postero-dorsal portion broad, depressed so 
 that rounded timbonal ridges are formed, which extend to the postero-basal 
 extremity, and the hinge ligament is hidden from sight by side view of the 
 shell. 
 
 Surface marked only by the ordinary lines and lamellations of growth. 
 
 Length and height of the largest example discovered, each forty-four 
 millimeters. 
 
 This species may be readily distinguished from all others by its sub- 
 circular, marginal outline and its extremely short and abruptly-rounded 
 posterior. The shortness of the posterior portion does not appear so con- 
 spicuously in the young shell as in the adult, because the additions by 
 growth are made more rapidly upon the basal and antero-basal borders 
 than elsewhere. 
 
 Position and locality. Bitter Creek Group ; Black Buttes, Wyoming. 
 
 Unio Slioslionensis* (sp. nov.). Shell of ordinary size, broadly subel- 
 
 * The so-called tribal name is applied by the Indians themselves to their country or laud, riot to 
 the tribe. 
 
DESCRIPTIONS OF NEW SPECIES. 127 
 
 Hptical or subovate in marginal outline ; valves moderately and somewhat 
 regularly convex ; test not massive.; dorsal margin broadly arched ; front 
 margin regularly rounded ; basal margin broadly and regularly rounded ; 
 posterior margin somewhat abruptly rounded, the postero-dorsal portion 
 sometimes obliquely truncated and sometimes sloping to a more prominent 
 posterior extremity; beaks well denned, but not prominent; umbones 
 broadly convex. 
 
 Surface marked by the ordinary lines and lamellations of growth. 
 
 Length of the largest example in the collection, nearly seven centi- 
 meters ; height of the same, five centimeters. 
 
 This species bears some resemblance to U. Haydeni Meek, from the 
 Bridger Group, but differs from that species in its larger size, its convex 
 instead of straight dorsal margin, its rather more prominent umbones, and 
 its greater propor donate height. 
 
 Position and locality. Upper Green River Group; Henry's Fork and 
 Alkali Stage Station, Wyoming ; also in Lower Green River Group ; west 
 side of Snake River, six miles north of Junction Mountain ; Cliffs, four 
 miles northeastward from Vermilion Canon ; and Dry Mountains, North- 
 western Colorado. 
 
 Genus CORBICULA Miihlfeldt. 
 
 Corbicula Powelli (sp. nov.). Shell rather small, subelliptical in mar- 
 ginal outline ; valves thin, slightly but somewhat uniformly convex ; beaks 
 small, not prominent ; cardinal and lateral teeth well developed ; both 
 anterior and posterior lateral teeth finely crenulated transversely ; middle 
 cardinal tooth of each valve having a shallow vertical groove along its 
 middle ; a very faintly-raised ridge extends downward from beneath the 
 beak on the inner surface of each valve, and dies out before reaching 
 the base. Surface nearly smooth, but marked by fine lines of growth. 
 
 Length, twenty-three millimeters ; height, from beak to base, fifteen 
 millimeters ; thickness, eight millimeters. 
 
 This shell differs from typical forms of Corbicula in its elliptical out- 
 line, slight thickness, and in the delicacy of the test. All the species 
 associated with it, except an oyster, are exclusively marine forms. 
 
128 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 Specific name given in honor of Prof. J. W. Powell, geologist in charge 
 of the Second Division United States Geological and Geographical Survey. 
 
 Position and locality. Tertiary strata, probably late Eocene ; Bijou 
 Basin, forty miles east of Denver, Colorado. 
 
 Genus PISIDIUM Pfeiffer. 
 
 Pisidium saginatum (sp. nov.). Shell small, subcircular in marginal 
 outline ; anterior side slightly longer than the posterior ; valves inflated, 
 the convexity from beak to base being sometimes irregular in consequence 
 of one or more abrupt concentric flexures. 
 
 Surface marked by ordinary lines of growth. 
 
 Length, five millimeters ; height, five and a half millimeters ; thick- 
 ness, five and a half millimeters. 
 
 Position and locality. Bitter Creek Group; Alrny coal mines, near 
 Evanston, Wyoming. 
 
 Genus MESODESMA Deshayes. 
 
 MesQdesma Bishopi (sp. nov.). Shell small, subovate or subtrihedral in 
 marginal outline, moderately gibbous ; umbonal ridges somewhat distinct, 
 the posterior pair more so than the others ; umbones prominent ; beaks 
 small ; both anterior and posterior lateral teeth well developed and trans- 
 versely striated, as in Corbicula; cartilage pit beneath the beak small; car- 
 dinal tooth in front of it rather small and V-shaped; pallial sinus deep; 
 muscular scars distinct ; right valve unknown. 
 
 Surface nearly smooth, and marked by very fine lines of growth. 
 
 Length, about one centimeter ; height, about six millimeters. 
 
 This shell differs from typical forms of Mesodesma in its V-shaped car- 
 dinal tooth, transversely striated lateral teeth, and deep pallial sinus. 
 
 Specific name given in honor of Prof. F. M. Bishop, of Salt Lake City, 
 Utah. 
 
 Position and locality. Tertiary strata, probably late Eocene ; Bijou 
 Basin, forty miles east of Denver, Colorado. 
 
DESCRIPTIONS OF NEW SPECIES. 129 
 
 Genus CORBULA Bruguiere. 
 
 Corlula subundifera (sp. nov.). Shell of ordinary size ; marginal out- 
 line subtrihedral or subovate ; valves only slightly unequal ; beaks con- 
 tiguous ; umbones moderately prominent ; beaks incurved and directed a 
 little forward; front obliquely truncate, concave, producing indistinctly 
 defined anterior umbonal ridges ; abruptly rounded below to the basal 
 margin, which is broadly rounded; posterior extremity low, prominent, and 
 sharply rounded; postero-dorsal margin sloping from the dorsum to the 
 posterior extremity ; this margin of each valve is bent abruptly inward and 
 downward, producing a narrow, shallow furrow, bordered at each side by a 
 somewhat prominent ridge, which extends from behind the beak- to the 
 posterior extremity of the shell. 
 
 Surface marked by numerous, more or less strongly elevated, con- 
 centric folds, which disappear before reaching the anterior and posterior 
 margins. Between these folds, and upon those parts of the surface 
 unmarked by them, the surface is marked by ordinary lines of growth. 
 
 Length, twenty-five millimeters ; height, eighteen millimeters. 
 
 This species closely resembles C. undifer Meek, from the Point of Rocks 
 Group at Rock Springs, Wyoming, but differs from that species in its less 
 extended posterior extremity, its less angular posterior umbonal ridges, its 
 less sharply elevated, concentric folds, and in wanting the peculiar flattening 
 of the umbones between the posterior and anterior umbonal ridges which 
 that species possesses. 
 
 Position and locality. Bitter Creek Group; Point of Rocks, Wyoming. 
 
 Gasteropoda. 
 Genus SUCCINEA Draparnaud. 
 
 Succinea papillispira (sp. nov.). Shell rather small, ovate or subelliptical 
 in lateral outline; spire minute but prominent; last volution much expanded 
 and broadly convex. 
 
 Surface marked by the ordinary lines of growth, and, under a lens, 
 faint, close-set, revolving striae are to be seen. 
 
 Length, eleven millimeters; breadth of aperture, six millimeters. 
 
 9PG 
 
INVERTEBRATE PALEONTOLOGY. [win. 
 
 This species possesses peculiar interest from the fact that it is the first 
 Sucdnea that has been discovered in the Tertiary strata of that great region. 
 Although there are so few salient, specific characters in any species of the 
 genus, this shell , may be readily recognized by its minute spire, the length 
 of which is only a very small part of the full length of the shell, and also 
 by its broadly convex last volution. 
 
 Position and locality. Upper. Green River Group ; Alkali Stage Station, 
 twenty-two miles northwward from Green River Station, Wyoming. 
 
 Genus HELIX Linnaeus. 
 
 Helix riparia (sp. nov.). Shell of medium size, subconical; volutions 
 about five, moderately convex; suture slightly impressed; spire considerably 
 produced for a species of this genus, equal in length to about three-sevenths 
 of the entire length of the shell; proximal side of the last volution broadly 
 and continuously rounded from the outer side; umbilicus small, rather deep; 
 outer lip unknown; aperture oblique, broadly subovate in outline. 
 
 Surface marked by the ordinary distinct lines of growth. 
 
 Position and locality. Lower Green River Group; eight miles below 
 Green River Station, Wyoming. 
 
 * Helix periplieria (sp. nov.). Shell of ordinary size, sublenticular in 
 form; spire low and broadly convex; volutions about five, each broadly 
 convex between the sutures; the last volution abruptly, almost angularly, 
 rounded at the periphery of the shell; under side broadly convex and rounded 
 sharply into a small, deep' umbilicus. Lip apparently not reflexed. 
 
 Surface marked by the ordinary distinct lines of growth. 
 
 Peripheral diameter, about fifteen millimeters. 
 
 Position and locality. Bitter Creek Group; south base of Pine Valley- 
 Mountains, Utah. 
 
 Genus PUPA Lamarck. 
 
 Pupa incolata (sp. nov.). Shell small, turreted, regularly tapering to 
 the apex; volutions about six, convex, regularly increasing in size to the 
 aperture, the last one not being contracted; suture impressed; aperture sub- 
 ovate in outline, its length a little more than one-third that of the whole 
 shell; outer lip thickened, reflexed. 
 
DESCRIPTIONS OF NEW SPECIES. 131 
 
 Length, five millimeters; diameter of last volution, two millimeters. 
 
 This species is of about the same size as the recent species Pupafallax 
 Say, and closely resembles it in form and general character. 
 
 Position and locality. Upper Green River Group; Henry's Fork, Wyo- 
 ming, where it is associated with the following species: 
 
 Pupa arenula (sp. nov.). Shell minute, ovate; volutions five or six, con- 
 vex; suture impressed; aperture contracted; teeth of the aperture unknown. 
 
 Length, two millimeters. 
 
 This shell is of about the same size and shape as Vertigo ovata Say, and 
 in general aspect it closely resembles that species. It appears, however, to 
 be a true pupa; at least the characters which should separate it from that 
 genus are not apparent. 
 
 Position and locality. Upper Green River Group ; Henry's Fork, Wyo- 
 ming. 
 
 Genus NERITINA Lamarck. 
 
 Nentina volvilineata (sp. nov.). Shell small, subovate in lateral outline; 
 volutions three and a half or four, regularly convex; spire short, as is common 
 in this genus, but somewhat prominent; suture slightly impressed ; aperture 
 semilunar; inner lip broad, plain, flat, its inner edge not clearly seen, but if 
 crenulated at all, it is not conspicuously so. 
 
 Surface marked by numerous raised, revolving lines of unequal size, 
 which increase in number by implantation as the volutions increase in size; 
 the revolving lines crossed by the usual lines of growth, which give the 
 surface, upon some parts, at least, an indistinctly cancellated appearance 
 under the lens. 
 
 Greatest diameter of the largest example discovered, nine millimeters; 
 height, lying with its aperture upon the table, five millimeters. 
 
 Position and locality. Bitter Creek Group; Black Buttes, Wyoming. 
 
 Genus MELANIA Lamarck. 
 
 Melania Lanmda (sp. nov.). Shell large, elongate; volutions apparently 
 eleven or twelve, uniformly increasing in size, moderately convex, bearing 
 a revolving row of prominent, strong, outward projecting, laterally sharp- 
 ened tubercles, which extend from the apex to the aperture; suture linear; 
 
132 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 surface of the volutions on the distal side of the row of tubercles without 
 revolving striae, or having one or two indistinct ones; surface upon the prox- 
 imal side of the row of tubercles marked by numerous elevated, slightly 
 waved, revolving striae, which are more distinct about midway of the space 
 than elsewhere, and are very close together near the columella. Only three 
 or four of these striae appear upon the volutions of the spire, because the 
 remainder are covered by each succeeding volution. Aperture oval or sub- 
 elliptical; outer lip having a broad, shallow notch, the retreating angle of 
 which is opposite the row of tubercles, anterior portion moderately extended 
 and abruptly rounded to the columella. 
 
 Length, about nine and a half centimeters, when entire ; diameter of 
 the last volution, twenty-two millimeters. 
 
 This species is more nearly like a true Melanla of Old World type than 
 any of the so-called Melanians of North America with which I am ac- 
 quainted. 
 
 Position and locality. Tertiary strata ; Crow Creek, Colorado, where 
 it was obtained by Mr. W. Cleburn. 
 
 Genus HYDROBIA Hartmaiin. 
 
 Hydrobia recta (sp. nov.). Shell small, very slender, sides of the spire 
 straight ; volutions convex, apparently twelve or more, increasing regularly 
 and uniformly in size from apex to aperture. Surface marked by the 
 ordinary lines of growth. 
 
 Length of one example in the collection, nine millimeters ; diameter 
 of the last volution of the same, . one and a half millimeters. Other exam- 
 ples indicate a length nearly twice as great as that here given. 
 
 Position and locality. Bitter Creek Group ; Almy coal-mines, near 
 Evanston, Wyoming. 
 
 Hydrolna Utahensis (sp. nov.). Shell rather small, elongate-conical, 
 spire moderately produced, its sides straight or nearly so ; volutions about 
 six, convex ; suture impressed ; aperture ovate, a little longer than wide, its 
 distal extremity slightly angular, its anterior end prominent and rounded. 
 Surface marked by the ordinary lines of growth. 
 
DESCRIPTIONS OF NEW SPECIES. 133 
 
 Length, about five millimeters ; diameter of the last volution, nearly 
 two millimeters. 
 
 Position and locality. Bitter Creek Group ; west base of Mu-si-ni-a 
 Plateau, 1,000 feet below the summit, Utah. 
 
 Genus VIVIPARUS Montfort. 
 
 Viviparus plicapressus (sp. nov.). Shell rather under medium size ; 
 spire, cqnical ; sides nearly straight ; volutions about seven, convex, the 
 outer and anterior convexity of the last one continuous and uniform ; suture 
 impressed. At the distal side of each volution there is a small, more or less 
 distinct, revolving groove or furrow, by which that part is folded and closely 
 appressed against the proximal side of the adjacent volution, the fold form- 
 ing a slight projection upon the proximal side of the suture. Surface 
 marked by the ordinary lines of growth, and upon some examples there 
 appears a faintly raised revolving line or incipient angulation near the 
 middle of the outer side of the volutions. 
 
 Length, about twenty-five millimeters ; breadth of last volution, twelve 
 millimeters. 
 
 Position and locality. Bitter Creek Group ; Black Buttes, Wyoming. 
 
 Genus LEIOPLAX Troschel. 
 
 Leioplax f tiirricula (sp. nov.). Shell of ordinary size, elongate conical ; 
 volutions about eight, gradually increasing in size ; convex angular, the 
 angle being sharp, prominent, and situated a little in advance of the middle 
 of the side of the volutions of the spire ; suture slightly impressed ; last 
 volution broadly rounded from the revolving angle to the umbilicus ; umbil- 
 icus narrow, deep and marked within by two or three revolving lines. Sur- 
 face upon both sides of the revolving angle of the volutions marked more 
 or less distinctly by two or three revolving raised lines. 
 
 Length, thirty millimeters ; diameter of last volution, fifteen millime- 
 ters. This shell has the aspect of some forms of Goniobasis, but the presence 
 of an umbilicus excludes it from that genus. It also varies from the 
 typical forms of Leioplax, but appears to be more nearly related to this than 
 
134 INVERTEBRATE PALEONTOLOGY. [WHITE. 
 
 to any other established genus and is accordingly referred to it provision- 
 ally. 
 
 Position and locality. Bitter Creek Group ; Black Buttes, Wyoming. 
 
 Genus TULOTOMA Haldeman. 
 
 Tulotoma Thompsoni (sp. nov.). Shell moderately large, having the 
 general form of shells of this genus; spire elevated, its sides broadly convex; 
 volutions six or seven, their outer side flattened or only slightly ^convex ; 
 proximal side of the last volution also flattened or slightly convex, produc- 
 ing a more or less prominent revolving angle between them; suture linear 
 or faintly impressed ; umbilical chink minute or wanting. Surface of the 
 three or four first volutions of the spire convex and unmarked, except by 
 the ordinary lines of growth, but the last two or three volutions are con- 
 spicuously marked by prominent tubercles in two or three revolving rows, 
 extending to the aperture, and which sometimes seem to be connected in 
 their respective rows by slightly raised revolving lines. .The distal row of 
 tubercles is strongest and is situated near the suture, on its proximal side. 
 The proximal row is immediately upon the distal side of the suture, the 
 tubercles of which are more elongated transversely than the others, but not 
 so prominent. Between these two rows there is sometimes another obscure 
 one, but upon some shells it is reduced to only a raised line. 
 
 Length of a large example, thirty-eight millimeters ; diameter of the 
 last volution, twenty-five millimeters. 
 
 This shell resembles the recent species T. magnified Conrad, but differs 
 from that shell in its more convex volutions, its faintly impressed suture, and 
 the different arrangement of its tubercles. It also resembles T. ( Viviparits} 
 Strossmayeriana Pilar, as published by Brasilia, but differs in the less con- 
 vexity of its volutions, especially the proximal side, and in the different 
 character and position of the tubercles that adorn its surface. 
 
 Genus PHOKUS Montfort, 
 
 Phorus exonerates (sp. nov.). Shell small, concavo-convex, the convexity 
 of the upper side being slight and nearly uniform ; volutions one and a half 
 or two; suture not distinctly shown; surface apparently quite plain or marked 
 
DESCRIPTIONS OF NEW SPECIES. 135 
 
 only by lines of growth; without extraneous bodies attached to the periphery; 
 aperture very oblique and very narrow. 
 
 Diameter of the shell, thirteen millimeters. 
 
 Position and locality. Tertiary strata, probably late Eocene; Bijou 
 Basin, forty miles east of Denver, Colorado. 
 
OH A.1? TEH, IV. 
 
 GEOGRAPHIC DISTRIBUTION OF THE GEOLOGICAL 
 FORMATIONS IN THE UINTA MOUNTAINS 
 
 AND A DISTRICT OF COUNTRY ADJACENT THERETO. 
 
 I propose to give a brief description of the geology of a part of the 
 Uinta Mountains and a district of country lying to the north, stretching 
 beyond the Union Pacific Railroad. The region is embraced within the 
 meridians of 108 30' and 109 52 7 .5 west longitude, and between the par- 
 allels of 40 15' and 41 40' north latitude. The Green River runs through 
 the middle of the district, having a general northerly and southerly course, 
 but from which it deflects in great curves. 
 
 The Uinta Mountains are composed of elevated valleys, tables, and 
 peaks, the latter having a very irregular distribution, due to geological 
 structure. The axis of the range is the axis of a great flexure, having a 
 total displacement (or exhibiting an upheaval) of more than 30,000 feet, 
 This flexure terminates on the east in the little valley separating the Uinta 
 Mountains from Junction Mountain. The latter represents a short, abrupt, 
 anticlinal flexure, having a north and south axis The Uinta uplift lias 
 brought up all of the Mesozoic and Carboniferous Groups with the Uinta 
 Sandstone, and in one locality a still older group of rocks, viz, the Red 
 Creek Quartzite, is exposed. On the flanks of the range, both to the north 
 and south, Cenozoic groups are found. The grand Uinta displacement is 
 only a flexure in its general characteristics, as the down-throw on the north 
 side of the axis is, in some localities, in part produced by faulting; while 
 on the south side of the axis faults are found having throws on the north 
 side of the fissure. Thus the faults, instead of being a part of the general 
 
 136 
 
RED CHEEK QUAETZITE. 137 
 
 flexure of the slope, are opposed to it, and the faults themselves, in a part 
 of their courses, change to flexures. In addition to the complications thus 
 mentioned, there are other minor flexures within the greater. All of these 
 complications will be spoken of further on. 
 
 Within the district which I undertake to describe, another great flexure 
 must be mentioned. This has a north and south axis, and brings to view in 
 the region north of Aspen Mountain the Sulphur Creek Cretaceous. On 
 the flanks of this flexure we find the Salt Wells and Point of Rocks Creta- 
 ceous, and the Bitter Creek, Lower Green River, Upper Green River and- 
 Bridger Tertiaries, all of which groups took part in the movement which 
 made this flexure ; but there is no evidence that the Brown's Park Group or 
 the Bishop Mountain Conglomerate was involved in the movement. The 
 southern extremity of the flexure is well seen at the head of Red Creek, 
 where the rocks dipping south from the end of the Aspen flexure become 
 horizontal, and again are turned up by the great Uinta flexure, thus forming 
 a synclinal between the flank of the greater flexure and the end of the 
 lesser. The characteristics of this displacement also will be discussed here- 
 after. 
 
 I now proceed to describe the geographic distribution of the groups or 
 formations in this district, and to give their general stratigraphic character- 
 istics, and also to note some interesting facts concerning their conformities 
 and unconformities. 
 
 All of the groups of rocks tabulated in Chapter II are found within 
 this area except the Grand Canon Group and the Grand Canon Schists. 
 
 EED CHEEK QUARTZITE. 
 
 The only locality where this group has been found within the territory 
 embraced in the discussion is in the vicinity of Red Creek, a small tributary 
 of the Green River, emptying into the latter at the head or western end of 
 Brown's Park. Its geographic extension is well shown on the map, and 
 needs no farther description. 
 
 Red Creek separates Quartz Mountain and Mount Wheeler by a tor- 
 tuous, flaring, craggy canon whose sides rise to an altitude of about "2,000 
 feet above the creek, and here the interior structure of the group is revealed. 
 
138 GEOGRAPHIC DISTRIBUTION. 
 
 The group embraced under the name is the lowest horizon found within 
 the region under discussion. It is composed in large part of a quartzite, 
 very crystalline and white, and having the general aspect of virgin quartz. 
 Only in a few places is the original granular structure apparent. Intimately 
 associated with the quartzite are very irregular aggregations of hornblendic 
 and micaceous schists, the latter sometimes bearing garnets. Originally 
 these schists were perhaps argillaceous strata between the thicker strata 
 of pure siliceous sandstone. The whole group has been greatly metamor- 
 phosed, producing a crystallization that in many places has quite, and in the 
 remainder almost, obliterated the original granular or sedimentary structure, 
 so far as it is apparent to the naked eye. Besides this recrystallization they 
 have been profoundly plicated, or I should rather say implicated. It is 
 only in a general way that any original stratification can be observed. 
 This original structure can best be seen when standing at some distance 
 from the beds to be studied. 
 
 Its relation to the Uinta Sandstone above it is exhibited in the lower 
 end of the canon of Red Creek and along the escarpment which faces 
 Brown's Park on the south side of Mount Wheeler, up the canon of an 
 intermittent stream four miles farther west, and also up the canon of Wil- 
 low Creek. Other facts relating to the junction of the two groups are seen 
 on the summit of Quartz Mountain. These facts are as follows: A part of 
 the Uinta Group, which is later and higher, terminates abruptly against the 
 quartzite. The thickness of the beds thus limited is about 8,000 feet, and 
 as the beds are traced from the southward to this plane of junction they 
 rapidly change from finer to coarser sediments, often appealing as conglom- 
 erates in the vicinity of the quartzite; but the total thickness of the beds 
 is not increased by the transition from finer to coarser sediments, though 
 particular beds may thicken, such thickening being compensated by the 
 thinning out or disappearance of others. In these conglomerates the coarser 
 materials are of quartzite, hornblendic rock, &c., similar to those of the' Red 
 Creek Group, held in a matrix of siliceous, hornblendic and micaceous 
 sands, w r hich are quite ferruginous. The position of the quartzite is on the 
 flank of the great Uinta flexure, not its axis, and the junction of the lower 
 two or three thousand feet of the Uinta Sandstone with the quartzite is not 
 
EED CREEK QUARTZITE. 
 
 139 
 
 seen; while from two to three thousand feet of the upper members of the 
 Uinta Sandstone were deposited over the summit of the quartzite. 
 
 From these facts we may safely infer that this was a great headland of 
 quartzite standing- out in the old Uinta Sea from some island, or perhaps 
 from the mainland ; that it rose above its waters as a lofty mountain, while 
 from two to three thousand feet of these sandstones, whose junction with 
 the quartzite is unseen, and while 8,000 feet of sandstone whose junction is 
 seen, were deposited. Then this mountain headland was buried with two 
 or three thousand feet of the upper members of the Uinta Group. During 
 that great movement which began during Cenozoic time, and which has con- 
 tinued intermittantly unlil the present, and which has given us the Uinta 
 upheaval, this quartzite behaved in a general way as an integral part of the 
 sandstone, flexing when the sandstone flexed and faulting when the sand- 
 stone faulted. In the upper part of Figure 11 we have a diagram exhibiting 
 
 U. Uinta Group. K. Red Creek Quartzite. C. Cretaceous. 
 
 Fig. 11. Section and diagram of the Red Crock Unconformity. 
 
 the relation of these two groups as now seen ; the lower part of the same 
 figure represents a restoration of the same section to the position these two 
 groups held prior to the inception of the Uinta upheaval. It will be seen 
 that the old shore line, in vertical outline, was now a bold cliff against which 
 
140 GEOGRAPHIC DISTRIBUTION. 
 
 the waves of the Uinta Sea dashed, forming deep caverns in the mural rock, 
 and then at other horizons was a retreating slope. A further study of the 
 facts shows that on a horizontal plain the projecting rocks inclosed deep bays. 
 But we must remember that as the beds were deposited denudation pro- 
 gressed ; so that the slope seen does not represent it as it existed at any 
 one time during the deposition of the beds, but only the slope which was 
 finally produced. At the beginning of the Uinta epoch it must have been 
 much steeper than it is represented in the diagram. 
 
 About 10,000 feet of the Uinta Sandstone is found to have been de- 
 posited against the old quartzite headland before it was buried by the upper 
 members of the Uinta Group. Hence this headland must have been at 
 least 10,000 feet higii but doubtless the quartzite itself was steadily de- 
 
 O ' J 
 
 nucled during this time, 'and we may suppose that it wasted away by erosion 
 above quite as rapidly as it was buried below. Certainly this supposition 
 is not violent ; and this would lead to the conclusion that the great headland 
 was 20,000 feet high at the time when the lowest knowji number of the 
 Uinta Sandstone was formed. We may now with some degree of probability 
 resto.re in imagination one feature of that ancient geography and see a 
 mountain more gigantic in its proportions than any which now pierces the 
 clouds floating over North America, Stand on the great plain by the Platte 
 River and look at Long's Peak; on it pile all that can be seen of Pike's 
 Peak from the banks of the Arkansas, and over these place all of Gray's 
 Peak that stands above the same plain, and the mountain thus built up in 
 imagination would not equal in altitude this quartzite mountain, whose feet 
 were bathed in the old Unita Sea. Geologists have arrived at the conclu- 
 sion that these quartzites and schistic rocks which appear over man}' portions 
 of the earth were oriinnallv accumulated as sediments and subsequently 
 
 / */ 
 
 metamorphosed. In the case of this group the metamorphism was anterior 
 to the deposition of the sandstones as seen from the facts mentioned above, 
 viz, that the sandstones are composed of material denned from the meta- 
 morphic group. But the sandstones have great thickness and underlie un- 
 conformably an extensive series of Carboniferous rocks. From this we infer 
 that the quartzite is of great geological antiquity. 
 
DEVELOPMENT OF UINTA SANDSTONE. 141 
 
 UINTA GROUP. 
 
 As shown by the map, the great mass of the Uinta Range is composed 
 of sandstones of this group. Intercalated with the sandstones some shales 
 are found, the latter being arenaceous, with a small portion of argillaceous 
 material. In a few places the sandstones have assumed a crystalline struc- 
 ture, forming a quasi quartzite. The whole group is exceedingly ferruginous. 
 Thin seams of clay ironstone are often seen to separate the strata of sand- 
 stone, and many of the shales contain large quantities of iron. Many of the 
 sandstones are seen to be ferruginous on the interior when broken, but some 
 of the beds are buff and light gray on fresh surfaces. The general color 
 of the walls of the canons and mountain escarpments is red and brown, due 
 to the more complete oxidation of the iron. In the canons and gulches, 
 where bays of quiet water are formed, considerable accumulations of steel- 
 gray iron sands may often be seen. These sometime form a pigment which 
 the Indians of the region were accustomed to use as paint in former days. 
 
 The great mass of the sandstones are fine grained, but occasionally 
 throughout the series .strata of pebbles are found; near its junction with 
 the Red Creek Quartzite these are conglomerates. Those peculiarities or 
 markings of strata, known as ripple marks, are very abundant at many hori- 
 zons from the top to the lowest known strata and mud rills, and rain drop 
 impressions are sometimes found. A very few concretions have been found 
 in the group. Weeks and months have been spent in the search yet no fos- 
 sils have been found. Within the territory embraced in the description the 
 base of the group is never seen. The Green River runs along the axis of 
 the Uinta flexure for many miles but its bed is yet in the Uinta Sandstone 
 so that it is impossible to determine the entire thickness of the group, but 
 that which is exposed has a wonderful developement, no less than 12,500 
 feet of these sandstones and shales being 1 seen. 
 
 I have already stated my reasons for considering this formation to be 
 older than Carboniferous, and I have given it provisionally a Devonian color 
 on the map. Professor Marsh in his article in the American Journal of 
 Science and Arts, in the March number of 1871, "On the geology of the 
 eastern Uinta Mountains," in speaking of these formations says, " * * * * 
 and a subsequent examination of apparently a portion of the same series, 
 
142 GEOGRAPHIC DISTRIBUTION. 
 
 on the western side of the river, rendered it probable that a part of them at 
 least are of Silurian age." In that article the professor does not mention 
 the finding of any fossils in the formation, and on what facts his statement 
 is based I do not know ; but his conclusion is entitled to great consideration, 
 for, although his study of this region Was of short duration, he fully appre- 
 ciated the great series of formations brought into view by the Uinta upheaval, 
 and in clear comprehensive language gives, in the article mentioned, a sum- 
 mary statement of the structural geology of the eastern Uintas. 
 
 The following section was made by Mr. John F. Steward in the sum- 
 mer of 1871. It commences at Beehive Point at the head of Red Canon 
 and ends at the foot of the canon where the river debouches into Brown's 
 Park. Lower members of the group are seen farther down the river but are 
 not brought into the section. 
 
UNTTA SANDSTONE. 
 
 143 
 
 FIG. 12. SECTION. OF UINTA SANDSTONE EXPOSED IN 
 
 RED CANON. 
 
 I. 
 
 
 
 2,000 
 
 <J, 000 
 
 \ 
 
 0,000 
 
 Xo. 1, -J20 feet. Arena- 
 ceous shales and mi nil - 
 stones; gray, pink,aml 
 brown. 
 Xo. 2, 285 feet, Sand- 
 stones anilarouaceons 
 shales. 
 c, 2 feet. Sandstones ; 
 ilark brown. 
 b, 4 feet. Shales; not 
 well exposed. 
 c, 3 feet. Sandstones ; 
 gray ; coarse; break - 
 i i! g into irregular \ 
 fragteents on expos- 
 ure to the. weather. 
 /I, (in feet. Sandstones; 
 dark red; not well 
 exposed. 
 e, 7 feet. Sandstones ; 
 pinkish-gray; thinly 
 and irregularly lam- 
 innted. 
 /, lit feet. Arenaceous 
 shales ; dark purple; 
 very friable. 
 g, G feet. Sandstones ; 
 gray, 
 /<, xi Let. Arenaceous 
 shales ; dark gray 
 and purple ; not well 
 exposed. 
 /, ll'lifeet. Sandstones; 
 shaly. 
 Dip of 'tlie above, 80. 
 
 Xo. 3, 334 feet. Sand- 
 stone: thickly bedded; 
 'times 'coarse 
 Drained and becoming 
 a line conglomerate. 
 No. 4, 3,108 feet Dark 
 sandstones and arena- 
 
 
 
 _ 
 
 1 C, 237 
 8,000 
 
 10, 000 
 13, 000 
 
 9, 95 feet. Shales ; up- 
 per 2J feet purple : 
 next 5 feet greenish ; 
 all below brown. 
 Average dip, 20. 
 
 No. 5, 5,800 feet, lied 
 sandstones, with an 
 occasional thin and 
 inconstantstratum of 
 arenaceous shale; 
 sandstones aud con- 
 glomerates in many 
 places ; the lower 
 members containing 
 : manypebblesotwbitc 
 quartzito. These beds 
 are so massive and 
 homogeneous as not 
 to bo easily subdi- 
 vided. 
 
 - ' -.-.1 
 
 s 
 
 / 
 _/!/. . r , c ^ 
 
 z 
 1 
 
 
 
 i- :'.^'.'_'~ '.'.'.'-'. '.^} 
 
 --.':': : --;''J::^ 
 
 *&-jM 
 
 j ? "af < c. ) 
 
 -^ ..:::.-. vj 
 
 "-.'.*'* X/.^;*:] 
 
 v<^.~-- - , *^ - -'-.5*-y 
 
 .- .- _.....k 
 
 : ; ; r T- '\ 
 
 :..--.:.../.. -,..-..-j 
 
 . - - - - -~~^~o 
 
 rn^rn 
 
 tW^t! 
 
 ceous shales in alter- 
 nation. 
 a, 150 feet. Arenaceous 
 shales ; dark brown. 
 ft. ">(> i'eet. Sandstones ; 
 compact; dark red. 
 c, If) feet. Arenaceous 
 shales; thinly and 
 evenly bedded. 
 d, 11 5 feet. Sandstones; 
 massive ; dark red. 
 e, 30 feet. Arenaceous' 
 shales and thinly 
 bedded sandstones ; 
 reddish brown. 
 /, r> feet. Sandstones; 
 purple. 
 !7, "i i'eet. Arenaceous 
 sliales ; ]>urplc. 
 h, 20 feet. Sandstones ; 
 massive ; coarse; 
 purple, 
 i, 50 feet. Arenaceous 
 shales ; purple ; not 
 well exposed. 
 j, 270 feet. Sandstones ; 
 red ; coarse. 
 k, 5 feet. Arenaceous 
 shales; g''ociiish . 
 rather compact. 
 1, 375 feet. Sandstones ; 
 massive ; red. 
 in, 18 feet. Arenaceous 
 shales ; dark purple; 
 tine texture, 
 n, 170 feet. Sandstone; 
 massive ; rod. 
 o, 7f>0 feet. Arenaceous 
 shales ; purple and 
 red above ; greenish 
 in middle, aud brown 
 and black at base. 
 
 
 \tiMSm 
 
 :. .:.:.:.{ 
 
 '^-- : v j.'-;::l 
 
 ....-...ifr/J 
 
 
 
 
 4 
 
 
 
 -::.-. ::-. --^ 
 
 %& 2 <?"/,? 2sf2] 
 
 
 / 
 
 
 mrn^ 
 
 
 ^ ^-I-E^ 
 
 e a a ," " o'o\ 
 
 " " o"o n r C C "] 
 
 
 =i=j? 
 
 ^ " f>0 e J ) 
 
 
 =f 
 
 ,,,^ 
 
 
 
 massive; purple and 
 brown. 
 
 
144 GEOGRAPHIC DISTRIBUTION. 
 
 A good section can be obtained by passing- over the 6-wi-yu-kuts 
 plateau. On the northeast, this plateau culminates in a high ridge of cherty 
 and brecciated limestone which is the base of the Red Wall Group. By 
 starting at the eastern extremity and foot of this ridge and going southwest- 
 ward across the plateau and descending into Brown's Park until the axis ol 
 the flexure is reached, you pass over the upturned edges of the Uinta Sand- 
 stone. This section gives a thickness to the beds of more than 13,000 feet. 
 The factors used in the measurement were the distance between the extrem- 
 ities of the line along which the section was made as determined by the 
 topographers, and the observed dips along the line at subequal distances 
 of about 200 yards. In 1871 we attempted to make a section from the axis, 
 through the Canon of Lodore, but the difficulty of navigating the river was 
 so great that we could not perform the task with satisfaction; but the thick- 
 ness of the beds found along this line was not less than 13,000 feet. 
 
 The Uinta Sandstone crops out along the base of the wall through the 
 upper part of Whirlpool Canon. On the north side of the Yanupa Plateau, 
 south of the Yampa River there is a monoclinal flexure and fault by which 
 the Carboniferous rocks are uplifted several thousand feet. There are three 
 cations running across this displacement which cut through the Carbonif- 
 erous rocks and reveal in their walls several hundred feet of the upper 
 members of the Uinta Group. The anticlinal uplift which forms Junction 
 Mountain is bisected by the Yampa River. The gorge through which the 
 river runs is called Junction Mountain Canon. In the heart of the canon 
 Uinta Sandstones are seen. 
 
 UNCONFORMITY AT THE SUMMIT OF THE UINTA GROUP. 
 
 A period of erosion or dry land condition intervened between the deposi- 
 tion of the Uinta Sandstones and of the Carboniferous Groups, 
 
 In Whirlpool Cm! on the red sandstones of the Uinta Group are thrust 
 up into the sandstones and shales of the Lodore Group, and in some cases 
 almost sever them; that is. the Uinta Sandstones were deeply eroded into 
 abrupt valleys with steep cliffs, some of them 400 feet high, anterior to the 
 deposition of the Lodore Group. There is a difference of dip between the 
 
UNCONFORMITY OF THE SUMMIT OF THE UINTA GKOUP. 145 
 
 two groups of about four degrees, the lower group having the greater incli- 
 nation to the south. 
 
 The following section illustrates the facts observed here : 
 
 1,000 5,000 feet. 
 
 R. Red "Wall Group. L. Lodore Group. V. Uinta Group. 
 
 Fig. 13. Section showing the unconformity between the Lodore and Uinta Groups in Whirlpool 
 Canon. 
 
 At the foot of the Caiioii of Lodore the unconformity is represented by 
 a difference of dip of from 5 to 6 degrees, and the Lodore Group steadily 
 overlaps the upper members of the Uinta Group, cutting off more than 
 2,000 feet of the latter. Here, also, the Uinta Sandstone is protruded into 
 the Lodore shales. These facts are illustrated in the following section : 
 
 5.000 feet. 
 
 R. Red Wall Group. L. Lodore Group. U. Uinta Group. 
 Fig. 14. Section showing the unconformity between the Lodore and Uinta Groups in the Canon 
 
 of Lodore. 
 
 On the northeast side of the 0-wi-yu-kuts Plateau the Lodore Group 
 is" wanting, and the massive limestone at the base of the Red Wall Group 
 rests upon the Uinta Sandstone. In passing from the northwest end of the 
 ridge along the strike of the sandstone to the southeast, the upper beds 
 of the Uinta Sandstone are seen to disappear, having been cut off by erosion 
 before the deposition of the limestone, and there is from one to two thou- 
 sand feet more of the Uinta Sandstone at the former end of the ridge than 
 at the latter. 
 
 This unconformity can also be seen in the cation of Junction Mountain, 
 and it has been observed on the southern side of the Uinta Mountains, west 
 of the district covered by the map, in the canon cut by the tributaries of the 
 
 Uinta River. 
 10 p ci 
 
146 GEOGRAPHIC DISTRIBUTION. 
 
 THE CARBONIFEROUS GROUPS. 
 CERTAIN GEOGRAPHIC DISTRICTS DESIGNATED. 
 
 In describing the geographic distribution of the Carboniferous and 
 Mesozoic Groups it will be found convenient to designate under general 
 terms certain districts of country, as follows : 
 
 FLAMING GORGE DISTRICT. . 
 
 There is a belt of country, extending from Bruce Mountain westward 
 to the border of the map, where most of the Carboniferous and Mesozoic 
 arid certain of the Cenozoic formations are turned up on edge, so that in a 
 limited area nearly all these groups can be studied. The Green Eiver enters 
 the Uinta Mountains by a flaring, brilliant, vermilion gorge, a conspicuous 
 and well known locality, to which, several years ago, I gave the name 
 Flaming Gorge, and this name has been generally accepted. I shall call 
 this the Flaming Gorge district. 
 
 PO CANON DISTRICT. 
 
 East of Bruce Mountain, for many miles, the Uinta displacement is 
 chiefly by faulting, and with slight exception the Carboniferous and Meso- 
 zoic Groups have been carried down and are concealed. But southeast 
 from Diamond Peak the displacement changes again into a flexure, and once 
 more the Carboniferous and Meaozoic Groups are found turned up on edge. 
 This region is at the eastern end of the 0-wi-yu-kuts Plateau, the plateau 
 itself culminating in a high monoclinal ridge at its eastern extremity, and 
 the plateau is bounded on this side by a deep monoclinal canon which divides 
 it from a region of Mesozoic and higher Carboniferous hogbacks. This 
 canon is also a well marked and well known geographic feature. Some 
 years ago I gave it the name Po Canon, and that name has been accepted 
 throughout the country. This I shall call the Po Canon district. 
 
 YAMPA DISTRICT. 
 
 In the Yampa Plateau by a series of flexures and faults the whole Meso- 
 zoic and Carboniferous series are brought to view. East from the Yampa 
 Plateiiu there is a simple anticlinal upheaval where all these groups are 
 
CERTAIN GEOGEAPIC DISTRICTS DESIGNATED. 147 
 
 again seen. I shall call the Yampa Plateau and adjacent country, together 
 with the region embraced in the Junction Mountain uplift, the Yampa dis- 
 trict. 
 
 ISLAND PARK DISTRICT. 
 
 Finally, west of the lower end of the Canon of Lodore and Whirlpool 
 Canon there is a zone stretching to the westward where all these groups 
 are in like manner exposed. At the foot of Whirlpool Canon lies the beau- 
 tiful valley known as Island Park, which is embraced in this zone. I shall 
 call this the Island Park district. 
 
 LODORE GROUP. 
 
 This group of rocks is seen in Lodore Canon, from which locality it 
 takes its name. Here it fills valleys in the Uinta Sandstone and buries the 
 ancient cliffs and hills of the dry land period. These facts were set forth in 
 the last section. 
 
 The group is composed of soft sandstones and shales with conglomerates 
 at the base and against the ancient hill sides. Its outcrop on the northwest 
 side of the cation is of very limited extent and is not represented on the map, 
 but on the southeast side of the canon it mounts the wall for several miles 
 and appears in Dunn's Cliff, where its thickness was measured and found to 
 be 460 feet. Its outcrop is represented on the map by a narrow line. On 
 the north side of the Uinta Mountains these rocks have been seen at but one 
 point, viz, a little west of Beehive Point, and there is some uncertainty about 
 this observation. Carboniferous fossils have been found in these beds. 
 
 The area of the outcrop at the bottom of Whirlpool Canon is so narrow 
 that the color has not been introduced on the map in that locality. 
 
 RED WALL GROUP. 
 
 Extensive outcrops of the Red Wall Group are found on the flanks of 
 the Uinta Mountains. On the north side the entire group is composed 
 chiefly of limestone, many of the beds being cherty. On the south side of 
 the mountains many sandstones are intercalated with the limestone. About 
 ten miles from Flaming Gorge in a southwestely direction, these beds are 
 found dipping to the north, and as they are followed along the strike to the 
 
148 GEOGKAPHIC DISTRIBUTION. 
 
 westward they are seen to rise in a high monoclinal ridge. This ridge is 
 not well developed until we pass beyond the area embraced on the map. 
 Another outcrop is seen on the northwest corner of the 6-wi-yu-kuts Pla- 
 teau ; here the beds are standing vertically. On the eastern end of the same 
 plateau, in the Po Canon district, another outcrop appears where the beds dip 
 a little north of east in a lofty monoclinal ridge. The central mass of Junction 
 Mountain is Red Wall limestone, and the group crops out in an unbroken 
 but irregular zone along the south side of the Uinta Mountains on the east 
 side of the Canon of Lodore, in the Escalante Peaks, and on the west side of 
 the Canon of Lodore in the Island Park district. The Ti-ra-yu-kuts like 
 the Escalante Peaks are composed of the hard cherty limestones of the Red 
 Wall Group and are true flanking peaks. Here the beds all dip to the south 
 usually at a rather low angle, and along the northern margin of the outcrop 
 the cherty limestones stand in peaks. Another outcrop is seen at the bot- 
 tom of Split Mountain Canon, and, last, these limestones are exposed on the 
 Yampa Plateau on an escarpment formed by a fault or a monoclinal flexure 
 which faces the Yampa River, and which is crowned " by many towering 
 peaks. 
 
 All these outcrops are well represented on the map. 
 
 LOWER AUBREY GROUP. 
 
 This group is made up of rather soft sandstones with intercalated lime- 
 stones; altogether the rocks are much more friable than the last mentioned 
 group, and they also yield much more readily to atmospheric degradation 
 than the beds of the Upper Aubrey. Where the beds of the Red Wall and 
 Upper Aubrey Groups stand in monoclinal ridges the beds of the Lower 
 Aubrey are found in the inter-ridge or valley spaces. It is seen outcropping 
 in the vicinity of Flaming Gorge and extending in a narrow zone westward 
 beyond the region embraced on the map. On the east side of the 0-wi-yu- 
 kuts Plateau its outcrop can be traced along the eastern base of the mono- 
 clinal ridge, which is composed of Red Wall limestones as described above. 
 Here the valley lies between the two monoclinal ridges and is known as Po 
 Canon. These beds are also found on both flanks of the Yampa Plateau 
 and along the southern slope of the Uinta Mountains from its eastern extrein- 
 
LOWEE AUBREY UPPEE AUBEEY. 149 
 
 ity in a narrow zone to the western border of the region under discussion. 
 These beds outcrop again in Split Mountain Canon in a deep gulch running 
 westward from its head, and again on the Yampa Plateau. Here some of 
 its harder limestones are occasionally found standing in low peaks. 
 
 UPPER AUBREY GROUP. 
 
 In the Uinta Mountains the Upper Aubrey is composed of two mem- 
 bers, a massive, homogeneous, light gray sandstone at the base, which I 
 have called the Yampa Sandstone, having a thickness of a thousand feet or 
 more; and above, a cherty limestone from 150 to 200 feet in thickness, which 
 I have -called the Bellerophon Limestone. These beds from, their indura- 
 tion and homogeneity are well adapted to the formation of ridges. 
 
 The group is seen outcropping in the Flaming Gorge district, and in 
 a zone stretching westward from Horseshoe Canon for many miles. A little 
 patch has been caught in the fault on the west side of Quartz Mountain and 
 thrust between strata of Cretaceous Age, and its area is marked on the map. 
 The monoclinal ridge on the east side of Po Canon is of this age. It is seen 
 on all sides of Junction Mountain. Yampa Canon is carved through this 
 sandstone. Here the rocks dip to the south and the homogeneous Yampa 
 Sandstone on the north side of the canon is cut by a multitude of little can- 
 ons, the channels of rainy day brooks. The entire slope is minutely carved 
 in this manner and the spaces between the meandering canons in many 
 places are but narrow walls, and sometimes these walls are broken where 
 the channels approach too closely, and by this process buttes with narrow 
 bases, and towers and pinnacles are formed. Along the courses of these 
 intermittent streams great numbers of pot-holes are found. This topography 
 is too minute to be represented on the map. On the eastern end of the 
 Yampa Plateau this sandstone forms the slope of the plateau where it de- 
 scends into the valley, and is in like manner carved with innumerable 
 gulches whose courses are interrupted by pot-holes. 
 
 This group has an extensive outcrop in the Yampa Plateau, and finally 
 it has been traced from Whirlpool Canon westward beyond the limits of the 
 map. 
 
(50 GEOGRAPHIC DISTRIBUTION. 
 
 The outcrop of these Carboniferous groups has been traced from point to 
 point throughout the areas described above. In most places the exposures are 
 complete and the relations of the -beds can be well understood, and nowhere 
 has any unconformity between its members been observed. Nor has any 
 unconformity between the Upper Aubrey and the lower Mesozoic been 
 observed; but as the lowest beds of Mesozoic Age are of very friable ma- 
 terial, the exact junction is rarely seen. 
 
 In the line of the fault between the Flaming Gorge district and the Po 
 Canon district there is a fragment of Red Wall limestone, as seen on the 
 map, on the northwest corner of the (3-wi-yu-kuts Plateau, which was not 
 carried down by the fault ; i. e., the fault is to the north. 
 
 JTJKA TRIAS GROUPS. 
 
 SHINARUMP GROUP. 
 
 These beds are shales and soft sandstones, and hence in this region, 
 which is plicated, they are found in valley spaces. The Lower Aubrey on 
 one side and the Vermilion Cliff on the other stand in ridges. At the foot 
 of the cliff on the south side of Flaming Gorge the Green River runs into 
 the beds of this age and soon passes across them to enter the Upper Aubrey 
 beds. Looking westward a towering cliff is seen on the right and a .broken 
 slope on the left and a narrow valley immediately in front, which may be 
 followed untir the bank of Sheep Creek is reached ; then turning up Sheep 
 Creek that stream is found to run nearly its entire course, as represented 
 on the map, in beds of this age. The steep wall of vermilion sandstone on 
 the north side of this valley is, except at one point, an impassable barrier. 
 Eastward from Flaming Gorge the outcrop of the Shinarump Group is seen 
 in a narrow valley between two ridges, for about six miles, until it is cut off 
 by the great Uinta fault. 
 
 Outcrops are also found in the Po Canon district. Here again the beds 
 are found in the spaces between the ridges. The same is true along the 
 foot of the Yampa Plateau to the- east, south, and west ; and also in a general 
 way in its outcrop from the foot of Whirlpool Canon through the Island 
 Park district. But this topographic peculiarity is not shown on the map in 
 
JURA TRIAS GROUPS. 
 
 the last mentioned region, as the area of the outcrop of all of the Jura Trias 
 beds has its topography cut up so minutely by reason of many minor dis- 
 placements and transverse lines of erosion that only a generalized represen- 
 tation could be given. 
 
 There is an island of Shinarump beds south of Echo Park, lying at the 
 foot of the Yampa Plateau. 
 
 VERMILION CLIFF, WHITE CLIFF, AND FLAMING GORGE GROUPS 
 
 In this region the Vermilion Cliff and White Cliff Groups are massive 
 sandstones, and hence stand in monoclinal ridges. Sometimes the base of 
 the White Cliff Group is a series of softer beds, and two ridges are formed. 
 Elsewhere the White Cliff Group rises high over the Vermilion Cliff beds in 
 a wall which faces the axis of the Uiiita upheaval on either side. Through- 
 out this entire region the White Cliff sandstone is lighter colored than the 
 Vermilion Cliff Group and everywhere exhibits that oblique structure known 
 as false bedding. 
 
 The Flaming Gorge Group with its limestones and sandstones is of 
 heterogeneous stratification and breaks down into comparatively low hills, , 
 which are found on the backs of the great White Cliff ridges. The area of 
 outcrop is parallel and coextensive with that of the Shinarump Group, except 
 in the region near Flaming Gorge and the district immediately south of Echo 
 Park. 
 
 About four miles southeast from Diamond Peak there is a small outcrop 
 of the Flaming Gorge beds standing on edge, with the summit of the group 
 'facing the plateau or axis of the Uinta upheaval. 
 
 It is an interesting fact that the bad-land sandstones of the Flaming 
 Gorge Group, both above and below the Mid-Group Limestone, are of fresh- 
 water origin. 
 
 The following is a section of the Jura Trias groups, made in the hills 
 and cliffs west of Flaming Gorge and beginning above at the base of the 
 conglomerate which underlies the teleost shales, and extending- to the summit 
 
 O / d 
 
 of the Bellerophon Limestone. In this region the limits of the section can 
 be easily determined. 
 
152 GEOGRAPHIC DISTRIBUTION. 
 
 SECTION OF THE JURA TRIAS GROUPS. 
 FLAMING GOEGE GROUP. 
 
 No. 1, 110 feet. Gray, greenish gray, pink, purple, and chocolate 
 beds ; very friable ; bad -land beds. 
 
 No. 2, '200 feet.- Bluish-gray limestone; Mid-Group Limestone. 
 
 No. 3, 500 feet. Coarse red sandstone ; (unio beds.) 
 
 No. 4, 250 feet. Limestone; bluish-buff; compact; sometimes slialy 
 and interstratified with orange shales and thin beds of gypsum. 
 
 WHITE CLIFF GROUP. 
 
 No. 5, 1,025 feet. Massive sandstone ; light gray and light orange, 
 everywhere exhibiting false stratification in many directions and at many 
 angles. 
 
 VERMILION CLIFF GROUP. 
 
 No. 6, 300 feet. Sandstone ; massively bedded ; gray, drab, and brown 
 within, but weathering with bright vermilion surfaces ; well exposed on the 
 summit of Flaming Gorge. 
 
 No. 7, 6 feet. Shales, somewhat argillaceous. 
 
 No. 8, 359 feet. Sandstones ; rather friable, with intercalated shales ; 
 the latter containing much gypsum ; weathering in variegated blight colors. 
 
 SHIN^.RUMP GROUP. 
 
 No. 9, 1,095 feet. Shales and sandstones containing much gypsum; 
 weathering in many colors, but brown and chocolate tints prevailing; in 
 many places constituting bad-land beds. 
 
 These beds all dip to the north at a great angle. 
 
 *********#* -x- 
 
 It will be seen that the Jura Trias groups are exposed in outcrops on 
 the north side of the Uinta Mountains in isolated patches, and these out- 
 cropping beds in the Flaming Gorge district dip to the northward. In the Po 
 Canon district they dip in a direction a little north of east. These two areas 
 of outcrop are separated by a long space where these groups are carried down 
 by the great Uinta fault, and their non-appearance at the surface is due 
 
THE CRETACEOUS GROUPS. 153 
 
 i 
 
 chiefly to this cause, as they are not usually covered on this side of the 
 range by unconformable Tertiaries. The exceptions will be noted hereafter. 
 
 On the eastern end of the Uinta Mountains, between the Po Canon 
 district and the Junction Mountain region, the upturned edges of Jura Trias 
 rocks occasionally protrude through the overlying unconformable beds of 
 Brown's Park age, but these' protruding masses are too small to be shown 
 on the map. 
 
 About the Junction Mountain uplift the eroded edges of the Trias are 
 sometimes buried beneath unconformable beds of Brown's Park acre. 
 
 o 
 
 On the south side of the Uinta Mountains the area of outcrop of the 
 Jura Trias groups is very much greater. Near the head of Ashley's Creek 
 the three upper groups of the Jura Trias are buried by unconformable rocks 
 of Tertiary Age. Farther west, beyond the area covered by the map, these 
 unconformable Tertiary rocks ride high up on the groups of Carboniferous 
 
 beds. 
 
 THE CRETACEOUS GROUPS. 
 
 The Henry's Fork Group, which is the lowest Cretaceous formation, 
 has an outcrop parallel and approximately co-extensive with the several 
 groups of Jura Trias; that is, like those groups it was brought up by the 
 great Uinta upheaval and the elevation of the Yampa Plateau. The same 
 is true of the higher Cretaceous groups, but the latter ate also brought into 
 view in the Aspen Mountain upheaval ; and hence, in the discussion of the 
 geographic distribution of these formations it is necessary to refer to a dis- 
 trict of country not heretofore mentioned in connection with the Carbon- 
 iferous or Jura Trias groups. 
 
 I shall call this the Aspen Mountain district. 
 
 HENRY'S FORK GROUP. 
 
 Nothing further need be said of the geographic occurrence of this form- 
 ation. The group is composed of sandstones, indurated arenaceous shales, 
 and conglomerates. These shales ring under the hammer, and are of steel- 
 gray color, and rarely afford footing to vegetation, and can be traced in a 
 bright band everywhere through the outcrop of the formation. The con- 
 glomerates contain many gravels and bowlders of pre-existing schistic rocks. 
 
154 GEOGRAPHIC DISTRIBUTION. 
 
 They have a much more extensive development on the south than on the 
 north side of the Uinta Mountains. 
 
 . On the south side of the Yampa Plateau, where the Fox Creek and 
 Cliff Creek flexures unite, the.se conglomerates stand on edge with a dip of 
 about 85 degrees to the southeast, and are firmly cemented, and stand as 
 high walls, separated by a long, narrow valley, strewn with fragments of 
 the conglomerate which have tumbled down from either side. Farther east, 
 along the southern slope of the Yampa Plateau, they are very conspicuous 
 features in the topography, as they are found standing in ridges and monu- 
 ments. Here the topography is exceedingly complex, too much so to be rep- 
 resented on the map which presents but a crude generalization of the many 
 wonderful features of this region. 
 
 SULPHUR CEEEK GEOUP. 
 
 These beds are soft argillaceous and arenaceous shales of dark color, 
 but sometimes weathering a light gray. By reason of their exceeding fria- 
 bility the areas of outcrop are everywhere valley regions, often diversified 
 with broad stretches of low, bad-land hills in many places quite naked of 
 vegetation, but elsewhere covered with patches of cactacece. Conspicuous 
 among these is a species of opuntia, with its minute, subtle thorns hedging 
 the hills with a threat of festering wounds. 
 
 Its most extensive area of outcrop is in the Island Park sag, and it has 
 a small outcrop in the northern portion of the Aspen Mountain uplift. 
 
 A fragment of these beds is seen southeast of Diamond Peak, which, 
 with a fragment of the Flaming Grorge beds on one side and a fragment of 
 Salt Wells on the other, is standing on edge. It will be noticed that these 
 beds dip toward the axis of upheaval, that is, the highest beds are found 
 nearest the mountain, and they all stand with an inclination from the horizon 
 
 of 90 degrees. 
 
 SALT WELLS GEOUP. 
 
 It is unnecessary to speak in detail of the outcrop of the Salt Wells 
 beds, as the attention of the reader has already been called to the outcrop 
 on the flanks of the Uinta Mountains and in the Aspen Mountain district. 
 It is worthy o.f remark that in the Uinta Mountain region these beds are 
 
THE CRETACEOUS GROUPS. 155 
 
 usually friable arenaceous and argillaceous shales, while in the Aspen 
 Mountain district they are arenaceous shales and thinly bedded sandstones, 
 itiid the greater induration of some of the beds in the last mentioned dis- 
 trict causes the valley spaces, which are characteristic of this group, to be 
 diversified with low ridges and cliffs. 
 
 POINT OF ROCKS GROUP. 
 
 The beds of this group can usually be divided into three somewhat 
 well defined members, the Upper Hogback, Middle Hogback, and Golden 
 Wall Sandstones, which are usually separated by a few feet of shaly sand- 
 stones, and these stratigraphic characteristics under conditions of upheaval 
 and erosion usually result in the production of three ridges, which are the 
 topographic features giving names to the several members. The upper 
 sandstone is usually massive and of light gray color weathering unequally 
 on exposed surfaces, which inequality is not determined by lines of stratifi- 
 cation. Here an irregular mass tumbles down and a cave is formed ; 
 there an irregular mass is more indurated than the general body to which 
 it belongs and stands in relief, often in some fantastic form; and such 
 weathering gives" the cliffs which are usually found along the outcrop of 
 these beds a strange and weird appearance. The general structure is sub- 
 concretionary, and true concretions sometimes weather out. The same 
 weathering is sometimes found in the Middle Hogback Sandstone. 
 
 The Golden Wall Sandstone is often homogeneous and of a bright 
 yellow color in the Uinta region, and often stands as a sheer wall ; hence 
 its name ; but in the Aspen Mountain district these yellow sandstones are 
 broken into strata, and light gray sandstones and shales are intercalated. 
 The ridge like topography characteristic of this group of beds so preva- 
 lent everywhere, renders it easy to trace every outcrop, and the peculiar 
 and persistent characteristics of the upper member greatly facilitate the 
 study of the relation between the Cretaceous below and Tertiary groups 
 above. In the Uinta Mountains the unconformity at this horizon is every- 
 where apparent. The difference in dip is from two to fifteen degrees, and 
 the evidence of intervening erosion is apparent ; but in the Aspen Mountain 
 
J56 GEOGEAPHIC DISTEIBUTION. 
 
 country the difference of dip is not easily distinguished, but the evidences 
 of erosion are usually apparent. 
 
 No evidence of unconformity between the Cretaceous formations has 
 been discovered, and the planes of demarkation in many places are not well 
 exhibited. In such a case the lines are drawn on the map only as approxi- 
 mations. Nor is there any evidence of unconformity between the lowest 
 Cretaceous and the highest Jura. Here, also, the stratigraphic plane is 
 sometimes obscure. The teleost shales contain the lowest Cretaceous fossils 
 which have yet been found, and the bad-land beds below the conglomerates 
 contain the highest Jurassic fossils found. The intervening conglomerates 
 I have thought best to call Cretaceous. 
 
 In a general way the horizon of conglomerates can be easily traced ; 
 still, it is a variable one. Here the sandstones are found with conglom- 
 erates of small pebbles which cannot be easily separated from the sand- 
 stones as they merge into them by imperceptible gradations. Elsewhere 
 well developed conglomerates are found, and sometimes heavy beds of 
 coarse conglomerate prevail. 
 
 * * * * * * * 
 
 The following section of the Cretaceous Groups was made on the east 
 side of the Green River above Flaming Gorge. 
 
 POINT OF ROCKS GROUP. 
 
 Upper Hogback Sandstone. No. 1, 60 feet. Sandstones; indurated; 
 light gray ; stained in patches with iron. 
 
 No. 2, 60 feet. Sandstones ; gray ; on exposed surfaces stained brown 
 with iron ; containing fragments of coal. 
 
 No. 3, 25 feet. Sandstones ; very massive ; light gray. 
 
 No. 4, 5 feet. Carbonaceous shales, with seams of coal. 
 
 No. 5, 35 feet. Sandstones ; indurated ; gray. 
 
 No. 6,18 feet, Carbonaceous shales, with seams of coal. 
 
 No. 7, 80 feet. Sandstones ; indurated ; dark gray. 
 
 No. 8, 60 feet. Sandstones ; massive ; light gray. 
 
 No. 9, 4 feet. Carbonaceous shales, with seams of coal. 
 
SECTION OF THE CRETACEOUS GROUPS. 157 
 
 No. 10, 110 feet. Sandstones; homogeneous; massive; light gray; 
 indurated. 
 
 Middle Hogback Sandstone. No. 11, 275 feet Sandstone ; buff; heavily 
 bedded with intercalated shales and seams of ferruginous clay. 
 
 No. 12, 75 feet. Friable sandstones and carbonaceous shales. 
 
 Golden Wall Sandstone. No. 13, 600 feet. Sandstones; yellow; rather 
 massively bedded, with intercalated carbonaceous shales. 
 
 No. 14, 80 feet. Sandstone ; massive ; bright yellow. 
 
 All the beds of the above group dip to the north about 45 degrees. 
 
 SALT WELLS GROUP. 
 
 No. 15 ? 1,860 feet. Friable sandstones and arenaceous shales. 
 
 SULPHUR CREEK GROUP. 
 
 No. 16, 2,000 feet. Dark argillaceous and arenaceous shales. 
 
 HENRY'S FORK GROUP. 
 
 No. 17, 25 feet. Conglomerates; pebbles very small, the largest not 
 being more than half an inch in diameter. 
 
 No. 18, 80 feet. Sandstones; mottled light gray and yellow; showing 
 false stratification. 
 
 No. 19, 70 feet. Shales; (teleost shales.) 
 
 No. 20, 135 feet. Sandstones ; rather heavily bedded above, but thinly 
 bedded below ; drab. 
 
 No. 21, 40 feet. Sandstones; coarse; buff. 
 
 No. 22, 100 feet. Sandstones': very friable; gray, greenish-gray, pink, 
 purple, and chocolate. 
 
 No. 23, 50 feet. Sandstones ; coarse ; sometimes appearing as a con- 
 glomerate of fine pebbles. 
 
 No. 24, 100 feet. Sandstones; gray, greenish-gray, pink, purple, and 
 chocolate ; very friable. 
 
 No. 25, 75 feet. Conglomerate ; dark ; in some places a coarse sand- 
 stone. 
 
 ******* 
 
153 GEOGEAPHIC DISTRIBUTION. 
 
 Below I reproduce the section made by Professor Meek oh Sulphur 
 Creek to which reference has been made in a previous chapter. I copy his 
 numbers and characterization of the beds, but group them in accordance 
 with the scheme presented in this report. I also invert the order. 
 
 SECTION OF THE EOCKS EXPOSED ON SULPHUE CEEEK, NEAE BEAE 
 
 EIVEE, WYOMING. 
 
 POINT OF ROCKS GROUP. 
 
 No. 1 (28), 200 feet. Numerous thin seams and layers of dark car- 
 bonaceous shales, with harder thin bands of various colored argillaceous, 
 arenaceous, and calcareous matter, including a few very thin streaks of coal ; 
 the whole being highly charged with vast numbers of fresh and brackish- 
 water shells, such as species of UniOj Corbicula, Gorbula, Pyrgulifera, Viri- 
 parus, Melampus, & c. Dip nearly east, about 75 below the horizon; thick- 
 ness 175 to 200 feet exposed. 
 
 No. 2 (27). A long space of perhaps 260 yards or more, with only a 
 few low exposures of light-gray sandstone, showing a slight westward dip. 
 
 No. 3 (26), 80 feet. Gray sandstone in place, apparently connected 
 with some masses (that may not be in place) so as to include space enough 
 for 60 to 80 feet, forms crest of a hill. 
 
 No. 4 (25), 800 feet. Brownish and reddish clays with a few distantly 
 separated thin beds and layers of gray sandstone, altogether 750 to 800 feet 
 in thickness. 
 
 No. 5 (24), 20 feet. Conglomerate and some red clays. 
 
 No. 6 (23), 40 feet. Whitish sandstone forms crest of hill about 220 
 to 240 feet in height. 
 
 No. 7 (22), 110 feet. Brownish clays and beds of sandstone, the latter 
 light gray below. 
 
 No. 8 (21), 60 feet. Brownish clays and sandy layers. 
 
 No. 9 (20), 40 feet. Greenish white sandstone. 
 
 No. 10 (19), 600 feet. Slope showing above some masses of con- 
 glomerate, like that of division 18, perhaps not in place, with, at places below 
 this, some reddish clays; altogether space enough for 500 to 600 feet in 
 thickness. 
 
SULPHER CEEBK SECTION, BY PROFESSOR MEEK. 159 
 
 No. 11 (18), 40 feet. Hard gray conglomerate, standing nearly ver- 
 tical, and forming crest of hill abput 350 feet high. 
 
 SALT WELLS GROUP. 
 
 No. 12 (17), 115 feet. Brownish and bluish clays, with some beds of 
 white, greenish, and brownish sandstones. 
 
 No. 13 (16), 45 feet. Clays and sandstone below, (20 feet), and gray 
 and brown pebbly sandstone above, (25 feet). 
 
 No. 14 (15), 125 feet, Bluish laminated clays, with, at top (left or 
 west side), a two-foot layer of sandstone, containing fragments of shells not 
 seen in a condition to be determined. 
 
 No. 15 (14), 40 feet. Ferruginous sandstone in thin layers, dipping 
 northwest about 80 below horizon. 
 
 No. 16 (13). A valley or depression showing no rocks, perhaps 150 
 yards across. 
 
 No. 17 (12), 150 feet. Light gray sandstones and clays, including a 
 bed of good coal, said to be 7J feet in thickness; all dipping south-south- 
 east 55 below horizon, and the sandstone above the coal containing many 
 casts, Inoceramus problematicus, with a few casts of Cardium and undeter- 
 mined univalves; altogether showing about 150 feet. 
 
 No. 18 (11). Slope and unexposed space, perhaps 200 yards or more 
 across. 
 . No. 19 (10), 20 feet. Light gray sandstone. 
 
 No. 20 (9), 255 feet. Gray sandy shales with alternations of sand- 
 stone and clays. 
 
 No. 21 (8), 95 feet. Heavy massive bed of light colored sandstone, 
 about 90 feet in thickness, standing nearly vertical, with some 3 to 5 feet of 
 sandy clay between it and the coal of division 7. 
 
 No. 22 (7), 7 feet 6 inches. Bed of good coal, said to be 7J feet in 
 thickness. 
 
 No. 23 (6), 100 feet. Greenish and bluish gray sandy clays, with 
 some d.ark shale at places. 
 
 No. 24 (5), 100 feet Two or three rather heavy beds of light yel- 
 lowish gray sandstone, separated by clays, probably occupying some of the 
 
160 GEOGRAPHIC DISTRIBUTION. 
 
 space included in division 4. Near the lower part two layers 15 to 18 inches 
 each, of sandstone, containing Ostrea soleniscus, Trapezium micronema, &c. 
 Altogether 90 to 100 feet or more. 
 
 No. 25 (4), 300 feet. Covered space, probably occupied by clays, 
 but showing some sandstone that may or may not be in place; perhaps 
 room enough for 250 to 300 feet. 
 
 No. 26 (3), 90 feet. Soft light grayish sandstone, nearly vertical. 
 
 SUMMIT OF SULPHUR CEEEK GROUP. 
 
 No. 27 (2), 100 feet. Slope apparently occupied by clays, thickness 
 " perhaps 100 feet or more. 
 
 No. 28 (1). Black shale, only seen in bottom of Sulphur Creek, thick- 
 ness unknown. 
 
 BLACK BUTTE QUARTZITE. 
 
 Southwest of Black Butte Station on the Union Pacific Railroad there 
 is a conspicuous topographic feature known as Black Butte. It is carved 
 from beds of the Point of Rocks Group and is crowned with a dark indurated 
 and exceedingly tough quartzite, which, in the distance, has the appearance 
 of a bed of extra vasated material, and even on closer examination I was 
 deceived by its apparent similarity to some rhyolites. 
 
 Rocks having a similar appearance and structure are found on the sum- 
 mit of Aspen Mountain, and I unhesitatingly considered the latter to be 
 quartzites; but, on visiting Black Butte, the general weathering and exceed- 
 ingly dark appearance of these beds created the impression that they had 
 been extravasated, though hand specimens had the appearance of quartzite, 
 and I left the field with many doubts as to their nature. Captain Dutton 
 has since made sections of this rock and examined them under the micro- 
 scope and pronounces it a quartzite. 
 
 Such a conclusion in connection with the geological relations of these 
 beds is very interesting Quartzites, from geological considerations of 
 structure and erosion, are usually supposed to have been at some time deep 
 seated and are often shown to have been involved in profound plication, or 
 
THE CENOZOIC GROUPS. 161 
 
 implication, and are usually considered to be metamorphosed sandstones, the 
 metamorphisin due to deep seated agencies ; but this quartzite is of very late 
 Cretaceous Age or may even belong to higher unconformable Tertiaries. 
 In either case the same strata on every hand are soft, comparatively friable, 
 granular sandstones ; they are immediately underlaid by great thicknesses of 
 sandstones of like characteristics. They have not been implicated or even 
 plicated. No extravasated material is found in the immediate vicinity to 
 which reference can be made as the origin of crystallization, and these beds 
 on Black Butte are more than 200 feet in thickness, and metamorphism from 
 contact with eruptive rocks, so far as my studies extend in this western coun- 
 try, is exceedingly slight, and indeed such slight change is rarely shown. 
 There is nothing in the surroundings to suggest metamorphism. 
 
 Is it possible that conditions obtained here favorable to the deposition 
 of silica by chemical precipitation? This question has been often suggested 
 by facts observed at many other places in the Plateau Province. In my 
 remarks on the Uinta Group I mentioned that some of the sandstones were 
 quasi quartzites, and where such beds of quartzite are found the quartzite 
 structure is invariably local. The same beds traced laterally are typical 
 sandstones ; and above and below, soft sandstones and excessively friable 
 shales are found, and there is no local disturbance of these beds. They 
 have simply been displaced in the grand upheaval in common with the sand- 
 stones and shales; and if this lithologic characteristic is due to conditions of 
 deposition and have not been imposed by the agencies of metamorphism, at 
 what place in the table of sedimentary groups shall we begin to consider 
 quartzites to be products of metamorphism? At Black Butte the quartzite 
 is as high at least as the very summit of the Cretaceous; in the Uinta Mount- 
 ains the quartzites are low down in the Paleozoic series and these are sepa- 
 rated by nearly 30,000 feet of sedimentary accumulations. May we go one 
 foot farther down in the rocks, but across the great gap of unconformity, and 
 say that the Red Creek quartzites were such from original constitution? 
 
 THE CENOZOIC GROUPS. 
 
 This description of the geographic distribution of the Cenozoic Groups 
 will be confined to the region north of the Uinta Mountains, except in the 
 11 P G 
 
162 GEOGRAPHIC DISTRIBUTION. 
 
 case of the Brown's Park Group and the Bishop Mountain Conglomerate. 
 A small strip of country on the south side of the mountains has been given 
 a Tertiary color on the map for the purpose of presenting an interesting 
 fact in the relation of the groups of that region ; but this is only the border 
 of a broad area through which Ceriozoic formations are distributed, and to 
 discuss this border with clearness it is necessary to enter into a consideration 
 of the whole area, which can be done much better when we have the map 
 of that country before us. 
 
 In the Uinta and White River basins, south of the Uinta Mountains, 
 where these Tertiaries have a great development, the lower formations of 
 this Age have been pretty thoroughly worked out, but there are higher beds 
 not so well understood. 
 
 I now turn to a consideration of the country north of the Uinta Moun- 
 tains. 
 
 BITTER CREEK GROUP. 
 
 Here the Bitter Creek beds have an extensive exposure on the flank of 
 the Uinta upheaval and on either flank of the Aspen Mountain uplift. 
 
 In the Flaming Gorge district, west of the Green River, the beds of 
 this group rapidly attenuate until they disappear, and here their lithologic 
 character is changed, as the fine grained friable sandstones are replaced by 
 conglomerates ; and as the beds here are dipping at a great angle to the 
 north, so that their upturned edges are well exposed, the harder conglomer- 
 ates are seen to stand in high ledges and walls. Eastward from the Green 
 River the beds rapidly thicken until, at Richard's Peak and Quien Hornet 
 Mountain, a section of more than 5,000 feet is presented, and here at the 
 base we have a great development of conglomerates. Richard's Peak itself 
 is a monoclinal ridge of this conglomerate. 
 
 The disappearance of these beds by attenuation on the west side of the 
 Green River and their increase above the normal thickness east of that 
 stream, together with the change in their lithologic constitution, leads us to 
 infer that we here have the beds exposed near the old shore line that was 
 established by the upheaval of the Uinta Mountain region. Conglomerates 
 are found at the base of the group in many places on the north side of the 
 Uintas, and I suppose the conglomerates on the west side of the Green 
 
THE CENOZOIC GROUPS. 163 
 
 River to be at the same horizon, namely, at the base of the series, and that 
 the attenuation is due to the non-deposition of the upper beds over the area 
 here brought to light, Of this, conclusive evidence was not obtained, and 
 it may possibly be that these conglomerates represent higher beds which, 
 farther from the shore, were sandstones of more thoroughly comminuted 
 material. But, while I suggest this possible explanation, I am inclined to 
 consider them as belonging to the lower members of the group, and that 
 after their deposition the area was left as dry land, while the sands were 
 accumulating in the bed of the lake farther from the axis of upheaval. 
 
 From the Green River eastward, nearly to the foot of Richard's Peak, 
 the base of the group is composed of bad-land sandstones with more indu- 
 rated beds intercalated ; the latter are usually light gray, sometimes quite 
 white ; the former are exceedingly ferruginous and sometimes shaly; but 
 from the western base of Richard's Peak, nearly to the outcrop of the Red 
 Wall limestone, conglomerates are found, and here the whole thickness of 
 the group is much increased. It is interesting to notice that these con- 
 glomerates are found opposite the outcrop of the Red Creek Quartzite. 
 But the materials of which the conglomerates are composed seem not to 
 have been derived from the quartzite, if I may trust my notes : and I should 
 here state that the geographic relation between the quartzite and the con- 
 glomerate did not occur to me while in the field, and in my notes on the 
 conglomerate I have mentioned that its bowlders are sandstones and lime- 
 stones, and that some of the latter contain Jurassic fossils; but I have 
 recorded observations at only two points one at Richard's Peak, the other 
 at Bruce Mountain. With the facts now at my command I am inclined to 
 think that when this conglomerate was formed, erosion had not progressed 
 through the Carboniferous groups and Uinta Sandstone so as to reach the 
 quartzite on the upheaved side, but that the conglomerate is composed of 
 sandstones from the Cretaceous groups, and limestones and sandstones of 
 the Jura Trias, and possibly, to some extent, from Carboniferous beds. It 
 would seem that the appearance of the conglomerate here is to be explained 
 by geographic, rather than by geological, considerations that is, the line of 
 exposure of the base of the group in this region is near to the old shore 
 line ; for it is manifest that here was a headland projecting from the Uinta 
 
164 GEOGRAPHIC DISTRIBUTION. 
 
 region into the old Bitter Creek lake, while westward, from 'Richard's Peak 
 to the Green River, the present exposure of the strata is across the bed of 
 an ancient bay. 
 
 West from Richard's Peak the plane of separation between the Bitter 
 Creek and Point of Rocks Groups is masked to a greater or less extent on 
 account of the exceeding friability of the lower beds of Bitter Ci'eek age ; 
 still careful examination reveals the fact that they are unconformable, and 
 this unconformity is very clearly exhibited at the eastern end of the mono- 
 clinal ridge, composed of the Upper Hogback Sandstone of the Point of 
 Rocks Group, near the foot of Richard's Peak, in an amphitheater of erosion 
 at the head of a dry gulch. 
 
 Between the western end of the outcrop of Red Wall limestone on the 
 northwest end of the 0-wi-yu-kuts Plateau and the Po Canon district the 
 base of the Bitter Creek series is not seen, as it has been carried down by 
 the fault. On the north side of Diamond Peak the Bitter Creek beds are 
 lying horizontal, and, studying this mountain from that side, it would seem 
 to be composed of Bitter Creek beds, perhaps capped by beds of the Lower 
 Green River, but on climbing the mountain its summit is seen to be composed 
 of angular fragments of sandstones piled in an indiscriminate manner, the 
 age of which was not fully determined ; descending it on the south side 
 this same confusion is observed. Of what the principal mass of this peak 
 is composed I do not know. 
 
 In the Po Canon district along the channel of Vermilion Creek and 
 many of its lateral tributaries, deep corrasion has produced many steep 
 escarpments of the Bitter Creek beds. Here we find the Point of Rocks 
 Group standingon edge, and near by, and separated from the former only 
 by narrow gulches, Bitter Creek beds of a horizon about midway in the 
 group are found lying hoiizontally; but in a few places lower beds of the 
 Bitter Creek series are turned up on edge with the Point of Rocks beds and 
 the middle beds of the Bitter Creek Group lie over their upturned and eroded 
 edges unconformably, and over some of the upper beds of the Point of Rocks 
 Group in like manner. Thus the middle beds of the Bitter Creek overlap 
 the lower beds, not because they were deposited over a broader area, but 
 because the lower beds in a part of their extent were exposed to erosion and 
 
THE CENOZOIC GEOUPS. 165 
 
 carried away prior to the deposition of the middle beds. These facts are 
 illustrated in Fig. 15. I do not think that the base of the Bitter Creek series 
 is found exposed in this vicinity. The displacement here has evidently been 
 exceedingly complex, and its study is rendered difficult by unconformities, 
 and it is not always easy to determine to which class of agencies certain 
 
 500 2000 1500 * NoTtll 
 
 B. C. Bitter Creek Group. P. E. Point of Rocks Group. 
 Fig. 15. 
 
 phenomena are due. In some portions of the line of displacement the beds 
 are marked by certain late Tertiaries of Brown's Park age as will be more 
 fully explained hereafter. 
 
 West of Bishop Mountain, stretching across the many tributaries of the 
 Vermilion, there is a broad expanse of country where the beds of this age 
 are exposed in naked bad-land hills, and on either flank of the Aspen Mount- 
 ain uplift they are seen usually forming regions sterile and desolate. 
 
 At the head of Little Bitter Creek there is a stretch of table land where 
 beds of Bishop Mountain Conglomerate are found. In the late redistribu- 
 tion of this conglomerate its materials have been carried quite over the line 
 separating the Bitter Creek from the Point of Rocks Group, so that the 
 junction is completely masked, but in the escarpment south of the plateau 
 which faces Quien Hornet Mountain the junction is well revealed ; and the 
 same is true farther to the north in lateral canons along the upper course of 
 Little Bitter Creek. The conglomerates found at the base of the series on 
 the flank of the Uintas are not seen on the flanks of the Aspen Mountain 
 uplift, and the Bitter Creek beds attenuate toward the north. From these 
 
 
 
 facts I infer that the materials of the Bitter Creek Group were derived in 
 large part at least from the Uinta region, that is that the bad-land rocks 
 of Mesozoic Age were carried from the Uinta region and redistributed as 
 bad-land beds of the Bitter Creek period. 
 
 In this great fresh water basin conditions favorable to the deposition of 
 
166 GEOGRAPHIC DISTRIBUTION. 
 
 carbonaceous shales and lignitic coal obtained from time to time, now here 
 now there, and such shales and coals are found distributed in great profu- 
 sion throughout the entire area which has been studied. In a section made 
 on the south side of the railroad between Lawrence Section House and Rock 
 Springs more than 30 seams and beds of coal are noted. The coals of this 
 horizon in the vicinity of Black Butte Station have been frequently described 
 by other geologists. 
 
 It is not my purpose to discuss the distribution and character of the 
 lignitic coals in this report. 
 
 LOWER GREEN RIVER GROUP. 
 
 In the Flaming Gorge district the Lower Green River Group overlaps 
 the Bitter Creek Group, and farther westward disappears by attenuation. 
 
 The course of the Green River from the northern border of the area 
 embraced on the map to the hogback six miles north of Flaming Gorge is 
 through the beds of this group, and an irregular escarpment of these beds 
 having deep reentrant angles, and spaces broken into low hills, faces the 
 axis of the Aspen Mountain uplift. The escarpment known as Pine Bluffs 
 on the east side of the uplift is of this age. Another outcrop is found north 
 of Dry Mountains and west of the Po Canon district, where their upturned 
 edges are exposed on the border of a basin of displacement or sag due to a 
 downthrow. 
 
 This group is composed chiefly of bituminous shales and impure lime- 
 stones, the latter being both arenaceous and argillaceous; but to the south, 
 near the Uinta uplift, the group is much thickened and the shales are replaced 
 by sandstones, and conglomerates of fine pebbles appear. 
 
 From this fact it is inferred that the beds of this group are derived from 
 the Uinta region, and that the material was supplied from limestones and 
 sandstones of Carboniferous Age. Conditions favorable to the accumula- 
 tion of Carbonaceous shales and lignitic coal are less frequent than in the 
 former period, but a fine bed of coal has been found at the base of this group 
 on the bank of the Green River, about eight miles below the station, and 
 Carbonaceous shales and thin seams of coal have been found at other hori- 
 zons elsewhere. 
 
THE CENOZOIC GROUPS. 167 
 
 UPPER GREEN RIVER GROUP. 
 
 ^JVI4 
 
 The beds of this group are well exposed in high escarpments on either 
 side of the Green River from the northern boundary of the district embraced 
 on the map nearly to the hogback six miles above Flaming Gorge, and they 
 stretch in a continuous but irregular belt on the west side of that stream for 
 the same distance, and are exposed on Henry's Fork for many miles. 
 
 On the east side of the Green River they are found in outlying discon- 
 nected patches. The most important of the latter are colored on the map. 
 They are also seen in the district east of Po Canon with their edges upturned 
 around the basin of displacement previously mentioned. It is probable 
 that these beds are also found east of Pine Bluffs, but when that country 
 was studied in 1868, I had not separated the Upper from the Lower Green 
 River beds, and not having visited the country since, I am not prepared to 
 give any facts concerning the matter. 
 
 In a former chapter I stated that the Upper Green River beds were 
 interpolated between Bridger and Lower Green River only through a por- 
 tion of the great Tertiary basin north of the Uinta Mountains. These beds 
 have their greatest development in the region about Green River Station, 
 extending for 20 or 30 miles to the north and south, and it is probable that 
 the material of which they are composed was derived in part, at least, from 
 other than the Uinta region, though doubtless this region yielded a share 
 of the detrital matter. Carbonaceous shales and lignitic coal are found at 
 this horizon on Henry's Fork. Two of the coal beds have been explored 
 and when tested are said to have yielded fair coals. 
 
 I have already in a former chapter described the Tower Sandstone at 
 the base of this group, and explained the nature of the unconformity between 
 the Upper and Lower Green River Groups. 
 
 BRIDGER GROUP. 
 
 The Bridger beds are found outcropping on the western border of the 
 district under discussion north of Henry's Fork, and again to the east of the 
 Po Canon district in the sag of displacement north of the Dry Mountains. 
 
 No unconformity has been discovered between the Bridger and Upper 
 
168 GEOGRAPHIC DISTRIBUTION. 
 
 Green River, and the plane of demarkation is obscure, or rather there is no 
 plane of demarkation, but the separation is transitional; but the bad-land 
 beds of the Bridger Group are very distinct from the limestones and sand- 
 stones of the Upper Green River. In the latter, sandstones usually rather 
 massive, and in the case of the Tower Sandstone greatly so, have impure 
 limestones intercalated. In the former, bad-land sandstones prevail, and these 
 are largely green sands, but irregular beds and aggregations of chalcedony 
 are abundant, and high in the series two well marked andr persistent lime- 
 stones are found. These beds of chalcedony afford the moss agates for 
 which the region about Fort Bridger has been noted. I suppose them to 
 have been deposited by chemical precipitation from waters highly charged 
 with silica. The limestones are in many places crypto-crystalline, and break 
 with a conchoidal fracture and often have the ring of phonolite. I consider 
 these also to be chemical precipitates. Fresh water fossils are sometimes 
 found imbedded in the crystalline masses, but can rarely be obtained in a 
 perfect state, but fossils are more abundant in the arenaceous and argilla- 
 ceous partings, and can be obtained in a good state of preservation. In the 
 green sands vertebrate fossils have been found in abundance, and concern- 
 ing them much has already been written by eminent paleontologists. 
 No coal has been discovered in the Bridger Group. 
 
 BROWN'S PARK GROUP. 
 
 These beds are found in the valley known as Brown's Park and a dis- 
 trict of country stretching thence to the southwest beyond the Snake and 
 Yampa Rivers. In Brown's Park they lie in a deep basin of erosion, the 
 bottom and sides of which are composed of Uinta Sandstone. This basin 
 is in the very axis of the Uinta uplift. Eastward, both on the north and 
 south sides of the area of outcrop, the beds are seen to rest unconformably 
 upon all of the Carboniferous, Mesozoic, and Cenozoic formations previously 
 mentioned. Its unconformity with the Upper Green River, Lower Green 
 River, and Bridger beds is well exhibited in the Dry Mountains in many 
 fine exposures. Its structural relations to these beds will be discussed here- 
 after. Its sandstones are bad-land rocks of exceedingly fine texture. In 
 
THE CENOZOIO GKOUPS. 
 
 some places these rocks are composed of thin laminae of many delicate 
 colors, but they do not readily part along the planes of stratification, but 
 crumble easily and often break in large masses. Extensive beds and irregu- 
 lar aggregations of chalcedony are found and I suppose them to have been 
 deposited by precipitation. Conglomerates are found, at the base, in some 
 localities having a great development. The beds incline slightly from the 
 wall of the park on the south side ; this inclination may be due to the bottom 
 on which they were deposited.- On the north side the beds are turned up at 
 a great angle, showing much displacement since they were deposited, and 
 immediately outside of the irregular line of outcrop a fault has been observed 
 with its throw to the south. 
 
 In Brown's Park the streams which come down from the mountains on 
 either side have in many places cut through these beds and reveal in the 
 depths of their channels the old floor of Uinta Sandstone. But a few hun- 
 dred feet of these beds are left in Brown's Park, but eastward a much greater 
 thickness remains preserved from denudation. It is probable also that this 
 greater thickness is due in part to greater sedimentation. 
 
 In the northeast portion of the Po Canon district there is another out- 
 crop of this group. Here the beds rest unconformably. on the Uinta Sand- 
 stone, the several Carboniferous groups, the several Mesozoic groups, on 
 Bitter Creek beds, and also on the heterogeneous mass of sandstones of 
 which Diamond Peak is composed. 
 
 BISHOP MOUNTAIN CONGLOMERATE. 
 
 This conglomerate is found only in isolated patches as remnants adven- 
 titiously preserved from the general erosion to which this widely spread 
 formation has been subjected. 
 
 An outlying patch or fragment is found on the north side of Sage Creek 
 overlying unconformably the beds of Lower Green River age. Another is 
 found on the plateau where Sage, Little Bitter, and Pretty Creeks have their 
 sources; here the conglomerate rests on Point of Rocks beds. Another is 
 found on the summit of Quien Hornet Mountain resting on Lower Green 
 River beds. Another is found on Bishop Mountain resting on Bitter Creek 
 beds. On the south side of the Uinta Mountains a fragment is found west 
 
170 GEOGRAPHIC DISTRIBUTION. 
 
 of Echo Park resting on Carboniferous beds. Another fragment is found ten 
 or twelve miles west of the Canon of Lodore resting on Carboniferous and Jura 
 Trias beds. A fragment is found west of Brush Creek also lying on the Car- 
 boniferous and Jura Trias beds; and the Wa-ka-ri-chits are capped with this 
 conglomerate, which here rests on Sulphur Creek beds. 
 
 These are the only fragments which I have discovered in the area em- 
 braced on the map, but to the westward, on both flanks of the Uinta uplift, 
 this formation has a much more extensive geographic development and it is 
 also found in greater thickness. On the north side of Connor Basin, at the 
 head of Sheep Creek, this conglomerate has a thickness of more than a thou- 
 sand feet. 
 
 There are some conglomerates on the peaks of the Dry Mountains 
 which at one time I believed to belong to this period, but I now think they 
 are of the Brown's Park age. 
 
 In the destruction arid redistribution of this formation, the materials of 
 which it was composed have been scattered in many places here and there 
 on either flank of the Uinta uplift. The conglomerate is composed of bowl- 
 ders and pebbles of sandstone, quartzite and crystalline schists, but sand- 
 stones and quasi quartzites probably of the Uinta period greatly prevail; 
 but in the original beds and redistributed materials found so abundant north 
 and northeast of Mount Wheeler where the Red Creek Quartzite is exposed, 
 white quartz and crystalline schists are far more abundant than elsewhere. 
 Sometimes at least the cement is calcareous. In the fragment west of Echo 
 Park large and somewhat angular blocks of Uinta Sandstone are found. 
 
 I think that many geologists would ascribe this conglomerate to the 
 action of ice, but throughout all that portion pf the Rocky Mountain region 
 which I have studied, I have so frequently found gravels and conglomer- 
 ates of sub-aerial origin, and have in so many cases found reason to change 
 my opinion concerning them, often having attributed a drift like deposit to 
 glacial action, and*afterward on further study abandoned the theory, being 
 able to demonstrate its sub-aerial origin, and witnessing on every hand the 
 accumulation of such gravels in valleys and over plains where mountains 
 rise to higher altitudes on either side, and having in many cases actually 
 seen the cliffs breaking down and the graveb rolling out on the floods of a 
 
THE CENOZOIO GKOUPS. 171 
 
 storm, I am not willing 1 to disregard explanations so obvious and so certain 
 for an extraordinary and more violent hypothesis. 
 
 Irregular accumulations of clay, accumulations of sand, of gravels, and 
 bowlders having in a general way all the lithologic characteristics of "drift" 
 are very common in the Rocky Mountain region, and in many cases I am 
 convinced that their origin can be traced to ordinary atmospheric agencies 
 acting on the adjacent hills and mountains; and no glaciers or icebergs are 
 needed for their explanation. 
 
 Nor need the thickness and extent of this Bishop Mountain Conglomer- 
 ate serve to weaken this explanation, for the sub-aerial gravels in the valleys 
 between the ranges in the Basin Province are of equal and often of greater 
 development. Whenever a low plain, valley or basin is for a comparatively 
 long period but little elevated above the base level of erosion, and during 
 this time mountains and hills stand about the lowlands, there must be a great 
 accumulation of drift, and where the highlands are areas of progressive ele- 
 vation and the lowlands areas of progressive subsidence this accumulation 
 may continue indefinitely. 
 
 Thus it is that I attribute the drift of the Rocky Mountain region to 
 sub-aerial agencies, chiefly the action of rains and streams. Mountains are 
 not degraded by the slow washing down of their surfaces but they are dug 
 down by the corrasion of deep channels and the undermining of ledges and 
 cliffs, and the materials thus loosened from the great rock masses to which 
 they originally belonged are carried down to the lowlands by storms. In 
 one hour of storm more material is carried to the lowlands than in days, 
 weeks, or months when the mountain streams are clear brooks. Yet there 
 has been glacial action in the Uinta Mountains, for there are found undoubted 
 
 MORAINAL DEPOSITS. 
 
 * 
 
 The deep valleys that lie at the feet of the axial peaks of this great 
 range have been beds of now extinct glaciers. Morainal deposits, roches 
 moutonneeSj glaciated grooves, and morainal lakelets are found in very 
 many of these elevated valleys. Often the valleys are so choked with the 
 materials thus accumulated by the action of ice that travel across them is of 
 great difficulty. From the crevices between these ice piled rocks high pine? 
 
172 GEOGRAPHIC DISTKIBUTION. 
 
 and firs are growing, and hundreds, thousands of little basins filled with 
 clear, cold water are found. These glacial deposits are doubtless of much 
 later origin than the Bishop Mountains-Conglomerate; often they are min- 
 gled with and masked by drift which has been brought down from the 
 heights by storms, and in many places it is impossible to separate that which 
 is due to this latter agency from that which is due to the agency of ice; and 
 as you descend the valleys away from the peaks where the glacial snow was 
 accumulated the mingling of the two increases by an increase in the amount 
 of drift until at last the glacial formation is lost and drift only appears ; taken 
 throughout the Uinta Mountains, the glacial material is far less in quantity 
 than the drift material. What I have thus described as glacial action is 
 exceptional or local and trivial as compared with drift agencies, which must 
 always obtain in mountain regions alike when they are free from glaciers or 
 when the elevated valleys are filled with ice. 
 
 Thus the glacial epoch in the Uinta Mountains was doubtless a reality; 
 the evidences of such a time are abundant, but they are found only high up 
 on the range, and the gravels and bowlders of the lowlands attest only to 
 the ordinary action of drift agencies. I may remark here that the evidences 
 of the same glacial epoch are abundant in the Park Mountains; but there 
 also the glaciers were confined to the elevated ranges. The gravel beds on 
 the lowlands are true drift. 
 
 LIGNITIC COAL. 
 
 But little reference has been made to the lignitic coals found in the 
 Uinta region; it is expected that the coals of the Plateau Province will be 
 discussed in a separate volume. 
 
CHAPTER 
 
 STRUCTURAL GEOLOGY. 
 
 In the preceding chapters many of the facts relating to the structural 
 geology of the region under discussion have been presented, but they were 
 given only to serve purposes relating to the subjects of which I was then 
 treating. In the first chapter it was necessary to refer to this region in 
 characterizing the three provinces; in the second, other facts were presented 
 in explanation of the grouping of the sedimentary rocks; and in the fourth, 
 still other facts were given in discussing geographic distribution. I now pro- 
 pose to assemble these facts with others relating to structural geology, for 
 the purpose of more clearly setting forth the geological structure of the 
 Uinta Mountains, Yampa Plateau, Junction Mountain, Diamond Peak, the 
 Dry Mountains, Brown's Park, and the Aspen Mountain district in the order 
 thus indicated. 
 
 DESCRIPTION OF ILLUSTKATIONS. 
 
 For the purpose of more clearly setting forth these facts certain illus- 
 trations have been prepared and will be found in the atlas. 
 
 Structure Sections. On Plate I is grouped a series of sections through 
 the Uinta Mountains, from south to north, and six miles apart. In each 
 section the structure observed has been projected below the line of sight 
 to the level of the sea, that the facts observed might be represented in a 
 more graphic manner. This hypothetic projection represents the most prob- 
 able condition of underground structure to that depth, yet there may be 
 unconformities unknown to us and of which no hint is given in the stra- 
 tigraphy at the surface or in the structural' geology . of the surrounding 
 country ; but from the absence of these indications, such unconformities 
 are rendered improbable. 
 
 As the Uinta upheaval began at the close of the Point of Rocks period, 
 
 173 
 
174 STRUCTURAL GEOLOGY. 
 
 this gives us a datum point from which to measure displacement, degrada- 
 tion in the region of uplift, and sedimentation in the region of downthrow. 
 For this reason the group is graphically accented in each section. 
 
 Displacement Diagrams. On Plate II is grouped a series of diagrams 
 designed to represent displacement and degradation. Each diagram corre- 
 sponds to and is derived from a section in Plate I, and is composed of three 
 lines: the sea level line and the surface line, which are the same as those in 
 the corresponding section, and a third, a displacement line, which is the 
 accented line of the section, projected in the region of uplift from the observed 
 outcrop of the group which it represents (Point of Rocks Group), to the 
 position it would have in the section had there been no degradation but 
 displacement only. 
 
 We thus take the sea level as the zero from which to measure displace- 
 ment; and by introducing the surface line, the accented line above becomes 
 a zero for the measurement of degradation in the region of uplift; and as 
 this accented line represents the position of the last bed deposited prior to 
 the inception of the upheaval (which is the highest Cretaceous bed), it also 
 forms a zero line from which to measure the sedimentation on the flanks of 
 the upheaval which occurred subsequent to the inception of the displace- 
 ment; or, in other words, a zero line from which to measure Post-Cretaceous 
 sedimentation. Hence in the region of downthrow, with the accented line 
 as the zero, the surface line measures the amount of Post-Cretaceous sedi- 
 mentation, minus an unknown loss by degradation. 
 
 It may be well here to explain the method by which the position of the 
 displacement line was determined. In the topographic survey the altitude 
 of many points on the surface is fixed with a reasonable approximation^ 
 accuracy by the use of the barometer and theodolite. These points are the 
 junction of drainage lines, the summits of peaks, and many other salient 
 and conspicuous topographic features ; and from these, contour lines are 
 drawn by inspection. Hence the topographic map fixes the position of any 
 bed appealing on the surface with all the accuracy necessary for the scale 
 on which these sections and diagrams are drawn. 
 
 Another factor used is the general thickness of the beds. This is deter- 
 mined by measuring them where they outcrop on the flanks of the uplift. 
 
DESCRIPTION OF ILLUSTRATIONS. 175 
 
 The surface lines, the outcrop of the beds along these lines, and the thick- 
 ness of the beds are factors sufficient for the construction of the sections and 
 diagrams, but the observed dips and strikes afford many valuable checks in 
 their construction. 
 
 A single diagram represents displacement and degradation in two dimen- 
 sions; that is, in a vertical plane from south to north across the axis of up- 
 heaval. A group of these diagrams constructed on parallel planes, separated 
 by equal intervals, and having the scale of these intervals in the group the 
 same as the vertical and horizontal scale of each diagram, serves to repre- 
 sent displacement and degradation in three dimensions. 
 
 Stereogram. To more fully bring the displacement into visual compre- 
 hension, the stereogram, Plate III, has been constructed. Here the lines 
 representing the level of the sea, and those representing the present surface 
 are omitted, leaving only the displacement lines; and between these others 
 have been interpolated, so that the intervals are but 3, 500 feet; and this has 
 the effect of projecting the region in relief, as it would appear in a bird's-eye 
 view had there been displacement but no degradation. To fully compre- 
 hend the meaning of this stereogram, it is necessary to remember that every 
 deviation of a line from horizontality represents a corresponding inclination 
 of the beds, and careful inspection will show that absolute horizontality very 
 rarely occurs. The stereogram fails to represent the abruptness of flexure 
 in some places, as the lines of displacement show the intersection of vertical 
 parallel planes with the summit of the reproduced bed, and these planes have 
 a north and south direction. Wherever they do not cross a flexure in the 
 direction of the dip, but to a greater or less extent oblique to it, to such 
 extent do the displacement lines fail to represent the abruptness of the flexure 
 or angle of dip ; in other words, the stereogram does not fully represent dis- 
 placement in an east and west direction. But the axis of flexure in the Uinta 
 Mountains has an easterly and westerly direction, and all other displace- 
 ments are subsidiary to this; and as the displacement lines are drawn trans- 
 verse to this axis, the general characteristics are well represented. It fails 
 also to give the relation of the displacement to the level of the sea except in 
 the case of the first line in the foreground. 
 
 I am indebted to Mr. Gilbert for this method of illustration. 
 
176 STRUCTURAL GEOLOGY. 
 
 It will be shown hereafter that pari passu with upheaval, degradation 
 progressed, and with downthrow, sedimentation, and it .is probable that 
 degradation and sedimentation were necessary to upheaval and downthrow. 
 Yet, for certain purposes, it is desirable that displacement be considered in- 
 dependent of the degradation with which in nature it must always be more 
 or less complicated, and hence the stereogram has been constructed. 
 
 BircVs-Eye View. The difference between upheaval and degradation in 
 the region of uplift can be determined by examining the diagrams in Plate II; 
 but to give a more graphic representation of this important fact in the Uinta 
 uplift, the bird's-eye view, Plate IV, has been constructed. 
 
 Other sections, diagrams and stereograms are found in the atlas, to 
 which reference will be made in appropriate place. All of these sections, 
 diagrams and stereograms are constructed on symmetrical scales; that is, 
 vertical and horizontal scales are the same and all agree with the map. 
 
 THE EASTERN PORTION OF THE UINTA MOUNTAINS. 
 DISPLACEMENT. 
 
 The Uinta Mountains have been produced by the degradation of a great 
 upheaved block having its axis in an east and wes't direction. This axis is 
 not a straight line ; in that portion of the range under discussion it makes a 
 great curve to the north; on the western border of the district the axis is 
 found at Leidy's Peak. It runs a little north of Mount Lena, and in Brown's 
 Park it passes about two miles north of Swallow Canon, then it deflects 
 
 southward and is found ag-ain on Vermilion Creek about four miles above 
 
 %. 
 
 its mouth. The total upheaval above the sea level, along its axial line, is 
 about 30,000 feet. The method by which the amount of uplift is ascer- 
 tained is as follows: It is in evidence that the upheaval began at the close 
 of the Point of Rocks period. The thickness of the rocks exposed on both 
 flanks of the uplift below that horizon is a little more than 25,000 feet, and 
 the lowest bed seen is 5,4.00 feet above the level of the sea. The Uinta 
 Sandstone has not been lifted as high at Leidy's Peak as it has at the mouth 
 of the Vermilion by about 2,000 feet, but the Mesozoic groups attenuate from 
 cast to west, in the same distance, something more than 2,000 feet, and 
 
DISPLACEMENT. 177 
 
 hence the summit of the Point of Rocks Group was earned about as high 
 in the western as in the eastern region. 
 
 O 
 
 From the axis on either side the beds are flexed in a gentle curve to 
 the north and south for many miles until the flanks of the range are reached, 
 where the beds are seen to drop down by abrupt flexures or faults, and 
 these lines of maximum displacement are subparallel with the axis. Thus 
 a great block having its longest axis in an easterly and westerly direction 
 was uplifted. In some places this block was severed from the adjacent 
 country by fracture; in some places by more or less abrupt flexure; and it 
 was itself flexed gently from the axis either way. Nothing more is needed 
 to explain the character of this uplift between the lines of maximum dis- 
 placement, but the latter present many interesting facts. 
 
 On Plate III, this portion of the Uinta uplift, together with the dis- 
 placements of the Yampa district are represented in a stereogram. The 
 general axis of the great uplift is easily recognizable, as is also the gentle 
 flexure in either direction from this axis. Then the great Uinta fault h, h, 
 h, h is seen on the north with the Flaming Gorge branch i, i. On the south 
 side of the Uinta Mountains in the Island Park district we find the north 
 Ti-ra-kav flexure />*, k, k and the south Ti-ra-kav flexure /, /, L In the 
 Yampa district on its northern border the eastern extension of the north 
 Ti-ra-kav flexure is scarcely seen, as there is an oblique area of upheaval 
 between the Island Park sag d, d and the Echo Park sag e. The flexure of 
 the Echo Park sag also becomes less abrupt in an easterly direction until it 
 almost fades out. The displacements south of the'Island Park and Echo 
 Park sags need no further mention here, as they will be discussed in a sub- 
 sequent portion of this chapter. 
 
 It will be seen in the Island Park district on the south side of the 
 Uinta uplift that there are two lines of maximum downthrow approxi- 
 mately parallel, the north and south Ti-ra-kav flexures ; the beds between 
 these two flexures are nowhere horizontal. The south Ti-ra-kav flexure 
 disappears toward the west until the region embraced in the stereogram is 
 passed ; a little farther westward it re-appears, sometimes as a flexure but 
 usually as a fault. Passing the oblique uplift between the Island Park and 
 
 *Echo Park sags we again have two lines of maximum downthrow. The 
 12 p G 
 
178 STRUCTURAL GEOLOGY. 
 
 more northern, which is a continuation of the northern Ti-ra-kav flexure, i# 
 but faintly seen in the stereogram ; the southern, which is the flexure of the 
 Island Park sag, is more pronounced. All of these maximum flexures on 
 the south side appear to be but slight from an examination of the stereo- 
 gram, as its scale is very small and no exaggeration has been permitted ; 
 but they are very important characteristics in the structural geology of the 
 region, and give rise to very remarkable topographic features. In the 
 broad generalization necessitated by the scale of the illustration many 
 minute displacements, parallel, oblique and transverse to these larger, dis- 
 appear ; that is, in the production of these greater flexures the beds were 
 locally contorted and broken. 
 
 Turning now to the north side of the Uinta uplift, we find that the line 
 of maximum displacement, beginning at the eastern extremity, is at first a 
 gentle flexure with comparatively small uplift; but the flexure rapidly 
 increases in abruptness and magnitude until at last we find that the beds are 
 broken and we have a fault ; but only a portion of the uplift is by faulting, 
 and the beds on the thrown side are turned up at the edge. Farther west- 
 ward the beds below lie nearly horizontal, and the beds on the upheaved 
 side are flexed downward; and these conditions alternate so that we some- 
 times have the upheaved beds flexed downward only, while the thrown beds 
 are nearly or quite horizontal. Again, we have the upheaved beds nearly 
 horizontal at the edge and the thrown beds decidedly flexed upward; and 
 another variation is found where the upheaved beds are flexed downward 
 and the thrown beds upward. 
 
 It is probable that the displacement began by flexure, and continued 
 until much of it was made in this way, and finally the beds broke, and the 
 latter part of the displacement was by faulting. And when this faulting 
 occurred, in some places the beds broke on the side of the flexure nearer the 
 axis, in other places on the side of the flexure farther from the axis, and in 
 still other places between the sides of the flexure ; that is, the line of fracture 
 meanders along the zone of flexure. As we approach the Flaming Gorge 
 district we find that the faulting is greatly diminished, while the flexing is 
 increased, the total throw or uplift, as we may please to consider it, remaining 
 approximately the same. At last this line of abrupt displacement branches, 
 
DISPLACEMENT. 179 
 
 and we have a faulted flexure to the south and an abrupt flexure to the 
 north; the southern branch, farther westward, becomes a simple flexure, 
 and the northern branch changes its course somewhat, so that the beds are 
 greatly warped; then it becomes a faulted flexure, and finally a clean fault. 
 
 Thus the great Uinta block was uplifted, behaving in part as an integer 
 to the extent that it was separated by flexure and fracture from the adjacent 
 country, and as a body of minute parts as it was flexed along the axial line. 
 
 We are interested to know at what rate this great uplift progressed. 
 The evidence bearing on this point is of three classes: first, that derived 
 from the character of the displacement itself; second, that derived from 
 degradation; and third, that derived from sedimentation. 
 
 The displacement is partly by faulting, partly by flexing. A priori, it 
 would appear that whether any given displacement should be by faulting 
 or flexing would be determined by four conditions, severally or conjointly: 
 first, rate of displacement; second, constitution of the beds displaced, flexi- 
 ble and brittle beds being contrasted; third, the depth of the beds consid- 
 ered, for the deeply seated beds, being less free to move, would be more 
 liable to bend, and beds nearer the surface, being more free to move, more 
 liable to break; and fourth, the nature or application of the force producing 
 displacement. Observed facts show that two at least of these a priori condi- 
 tions, the second and third, are true conditions. Both Mr. Gilbert and myself 
 have observed in the transverse section of a displacement that the hard beds 
 have been broken and the soft beds bent, and I have elsewhere published 
 such a section. 
 
 In a region of country visited by Mr. Gilbert during the past season, 
 he found that the displacement in one district was by faulting, and in an- 
 other by flexing. In the region of faulting there had been but little sub- 
 sequent degradation ; in the region of flexing, much subsequent degrada- 
 tion; and these conditions led Mr. Gilbert to the conclusion that the 
 depth of the beds below the general surface at the time of the displacement 
 had determined these characteristics, and in studying facts which had been 
 collected in other regions by myself, he was able to show that they also 
 lead to the same conclusions. The places where these facts were observed 
 are so widely spread throughout the Plateau Province that it will not ' be 
 
180 STRUCTURAL GEOLOGY. 
 
 convenient to assemble them here, but I am strongly disposed to accept 
 Mr. Gilbert's conclusions. 
 
 The fourth condition is supposable, but that it is a vera causa I cannot 
 nay. I have often supposed it to be such in the study of particular faults, 
 but on further study it has eluded my apprehension. We sometimes 
 iind a displacement of many thousand feet where the uplifted region is 
 separated from the thrown by a broad zone of gently dipping beds, 
 and it would seem a priori that where two regions were thus separated, 
 the. zone of change would be by flexure rather than by a series' of 
 ruptures, and such is usually though not invariably the case, and this seems 
 to be a question of application of force, or in other words, character of 
 strain, and it cannot be doubted that such a condition must be taken into 
 consideration. Mr. Gilbert- evidently recognizes it as a true cause, for in 
 discussing the Basin Ranges,Jie says: " The displacement of comparatively 
 rigid bodies of strata by vertical or nearly vertical faults, involves little hor- 
 izontal diminution, and suggests the application of vertical pressure from 
 below." 
 
 As to the first cause, rate of displacement, it is manifest that accelera- 
 tion promotes rupture, retardation, flexure; but the other conditions which 
 I have set forth so modify this rule, that rate of displacement cannot with 
 any certainty be determined from facts of flexure and rupture alone. 
 
 The Uinta upheaval was partly by flexing, partly by faulting, and if 
 there were no other conditions to determine these characteristics, we might 
 say that so far as the beds were flexed they give evidence of slow move- 
 ment; and so far as they were ruptured, evidence of a more rapid move- 
 ment; and the twenty -five or thirty -thousand feet of beds which cfcre 
 exposed to view and were involved in this uplift were chiefly of a character 
 quite brittle, and this increases the evidence in favor of #low upheaval by 
 flexing ; but flexing may have been at great depths, and the superincumbent 
 masses produced a condition favorable to flexing even in a rapid rate of 
 movement. Many substances, especially metallic, are known to flow under 
 great pressure, and it is probable that great pressure would produce in all 
 rocks a quasi-fluid condition, and hence we cannot say that flexing attests 
 to a slow rate. On the other hand, faulting, without considering other con- 
 
DEGRADATION. 
 
 * 
 
 ditions, would seem to attest to rapid rate, but the character of the strain 
 may have determined the rupture. Hence we may conclude that the 
 characteristics of the displacement do not afford satisfactory evidence of the 
 rate of its movement. 
 
 It will be seen hereafter that facts relating to degradation and sedimen- 
 tation do give some satisfactory conclusions. 
 
 DEGRADATION. 
 EXTENT OF DEGRADATION. 
 
 The area of degradation which I have often for convenience called the 
 region of uplift, represented in Plate II, embraces a little more than 2,800 
 square miles. From this about 8,300 cubic miles of rock have been carried 
 away by rains and rivers a mean degradation of about three cubic miles 
 to the square mile But a part of the region embraced on that plate will 
 be discussed hereafter under the head of Yampa Plateau, and in what I 
 have said concerning the Uinta Mountains above, this region has not been 
 considered. Taking the Uinta Mountain region proper, then, we have an area 
 of about 2,000 square miles from which about 7,100 cubic miles of rock have 
 been taken, giving a mean degradation of 3^ cubic miles to every square mile 
 of surface. But this has not been taken from all points equally ; a greater 
 amount has been carried from the axial region than from the districts along 
 the flanks ; and in the axial region a greater amount has been taken from 
 the eastern than from the western end. Here where the displacement lines 
 are carried highest, the surface lines are lowest, so that the degradation is 
 more, not only by the amount of greater uplift but also by an additional 
 amount in the deeper excavation of the valley. The 'region of highest 
 uplift is the region of lowest degradation, and here more than 25,000 feet 
 of beds have been removed. 
 
 To more fully comprehend the amount of degradation and its relation to 
 upheaval, the bird's-eye view, Plate IV, has been constructed. Here we 
 have represented a block from the Uinta Mountains forty miles in a north 
 and south, and fifty miles in an east and west, direction. The one-half of 
 the view in the foreground represents the degraded region, and the one -half 
 
182 STUCTURAL GEOLOGY. 
 
 in the background as it would appear had there been no degradation, but 
 uplift only. It is believed that a careful study of the illustration will be 
 amply repaid. 
 
 RATE OF DEGRADATION. 
 
 It would be interesting to know at what rate this degradation has pro- 
 gressed. We know of no means by which an absolute rate can be deter- 
 mined, but there are certain facts which lead to the conclusion that a 
 maximum rate for this region was never established. These facts are 
 found in the character of the topographic features produced by degradation, 
 but in order that we may more fully understand them it will be well to 
 .briefly examine the agencies, methods, and conditions of degradation. 
 
 Degradation consists of disintegration and transportation, and they are 
 mutually dependent parts of the general process. If disintegration is re- 
 tarded, transportation is retarded, for the materials must be furnished ready 
 for transportation. Again, if transportation is retarded, disintegration is re- 
 tarded, as the beds to be disintegrated are to some extent protected by the 
 accumulated products of the process ; and if either is accelerated, the other 
 must be accelerated. 
 
 DISINTEGRATION. 
 
 The rock masses which are brought above the level of the sea by up- 
 heaval are always found to be more or less coherent. Although these rocks 
 are chiefly of sedimentary origin, the exceptions being extravasated masses, 
 still they are usually found to have assumed a more or less crystalline struc- 
 ture, due either to the manner of their deposition or subsequent metamor- 
 phism, so that the minute parts, molecular or mechanical, of which these rocks 
 were originally aggregated, cohere in great masses. There are many degrees 
 of this coherence from bad-land sandstones or shales of extreme friability to 
 schists and granites of extreme coherence; but whatever may be their degree 
 of coherence, they must be disintegrated prior to their transportation to 
 
 the sea. 
 
 PETROLOGY AS RELATED TO DISINTEGRATION. 
 
 The endurance of rocks as determined by their coherence depends on 
 1. Geologic Structure. The rocks may be irregularly massed or strati- 
 
DEGRADATION. 183 
 
 fied ; the latter yield more readily than the former. The strata may be thick 
 or thin; the latter yield more readily than the former. The strata may be 
 horizontal or inclined, and the latter yield more readily than the former; 
 and in each condition above mentioned heterogeneity promotes disinte- 
 gration. 
 
 2. Litholoffic Structure. Under this head we may consider whether the 
 beds are compacted crystals or cemented sediments; the latter yield more 
 readily than the former, and heterogeneity promotes disintegration. Both 
 in detrital and crystalline rocks there are certain conditions which may be 
 grouped under the head of induration, including hardness and toughness, and 
 the greater the induration the greater the stability; and the law of hetero- 
 geneity applies also to this condition. 
 
 3. Chemical Structure. The principal condition of chemical constitu- 
 tion relating to endurance is solubility; the soluble yield more readily than 
 the insoluble, and in chemical constitution the homogeneous is more stable 
 than the heterogeneous. 
 
 It will thus be seen that in each particular mentioned above, the homo- 
 geneous is more stable than the heterogeneous, and these particulars in their 
 correlations are themselves conditions of heterogeneity, so that the whole 
 subject of petrology in its relation to disintegration, is one of degree of 
 
 heterogeneity. 
 
 DYNAMICS OF DISINTEGRATION. 
 
 The principal forces of disintegration are gravity, heat, crystallization 
 and chemical reaction. Gravity disintegrates the rocks directly where they 
 break from cliffs and ledges partly by their own weight, and are further dis- 
 integrated by the fall, and indirectly through the agency of water in abra- 
 sion. Heat disintegrates the rocks by change of temperature, and probably 
 by expansion of water permeating the rocks. Crystallogenic force also acts 
 through the agency of water, for where the water which has permeated the 
 rocks is frozen, the expansion due to this crystallization breaks them asun- 
 der. In chemical reaction the rocks are broken up through the agency of 
 water which acts directly in dissolving them, or indirectly in promoting 
 other chemical reactions. 
 
JS4 STRUCTURAL GEOLOGY. 
 
 In disintegration, therefore, we have an intricate plexus of forces acting 
 on an intricate plexus of matter. 
 
 Now, so far as disintegration depends on the forces of heat, crystalli- 
 zation, and chemical change, the climate of the region is involved, aridity 
 being contrasted wi,th humidity, heat with cold, and great changes in either 
 factor of climate promote disintegration ; and so far as disintegration de- 
 pends on gravity, the declivity of the surface exposed to degradation is in- 
 volved, and a breaking up of the general declivity into greater and lesser 
 slopes, promotes disintegration. We may, therefore, discuss the dynamics of 
 disintegration as conditions of climate and declivity, and hence we may 
 consider the factors of disintegration to be petrology, climate and declivity, 
 and affirm that if the rate of transportation is sufficient to allow the forces 
 of disintegration to act to their fullest extent, the rate of disintegration will 
 depend on the heterogeneity of the rocks, heterogeneity of climate, and 
 heterogeneity of declivity. 
 
 TRANSPORTATION. 
 
 Gravity is the force acting in transportation. It acts directly in trans- 
 porting masses which fall from ledges and cliffs, and indirectly through the 
 agency of water. In this indirect method there are two sources for the 
 mechanical motion involved in the process: the one is the force of gravity 
 inhering in the water, which is the vehicle of transportation, the other the" 
 force of gravity inhering in the rocks transported. Let us call the latter 
 rock power, the former water power, and the rock material transported, load. 
 
 It is manifest that if the rocks on disintegration were in a fluid state, 
 their owrrgravity would transport them. All of the rock material which is 
 dissolved is placed in this condition, and its own gravity is the force which 
 transports it; it does not float on the water, but behaves as an integral part 
 of it, and with it obeys the laws of hydrodynamics. In this case the water 
 is not the agent of transportation, but only the agent of disintegration. 
 
 When the rocks are disintegrated mechanically the water is properly 
 the vehicle of transportation, and we have two cases, the one in which the 
 load is driven by the water, the other in which it is floated on the water. 
 When the transported matter is driven by the water along the bottom of the 
 
DEGRADATION. 185 
 
 channel, both rock power and water power are employed, these two forces 
 acting in inverse ratio with the specific gravity of water and load; that is, 
 less water power is needed to drive the rock by the amount of the weight 
 of the water displaced by the rock, for to this extent, rock power is used. 
 
 The amount of load which may be transported by the driving process, 
 or in other words, by water power, plus an amount of rock power, begins 
 with that degree of comminution which permits the load to be moved, and 
 is limited by the power of the water on one hand and by friction on the 
 other. And wherever the degree of comminution is such that the matter 
 is transported partly or wholly by the agency of flotation to such 
 extent as flotation is employed, the driving ceases and other limits are 
 imposed. 
 
 We come now to the principal method of transportation ; that is, that 
 by flotation. Here the rock power is used in transportation, and the 
 water is the vehicle. If the matter to be floated is of the same or less 
 specific gravity than the water, a condition seldom obtaining, flotation is 
 perfect, and the water power is not used either in transportation or to pro- 
 mote flotation. But when the floating matter is of greater specific gravity 
 than the water, then the water power is used in promoting flotation. With 
 a given amount of water and sufficient supply of load, the extent to which 
 the water power will be utilized in promoting flotation will depend on two 
 conditions : First, the power of the water, which is measured by fall into 
 mass, or which may be expressed as velocity or again as declivity ; second, 
 it will depend on the relation which exists between the floating surface, or 
 surface presented downward, and the mass of each particle of the load. 
 In other words, it will depend on the specific gravity and comminution 
 of the load. If the specific gravity of the load is but little greater than 
 water, the velocity of the water becomes a very small factor, and the 
 amount which can be transported will be chiefly limited by the containing 
 capacity of the water, but this is a condition not actually found in nature. 
 The difference between the specific gravity of water and load is great, and 
 variable within such small limits that the variability may be neglected ; but 
 the relation between the floating surface and the mass of each particle of 
 load may be determined by another condition than that of specific gravity, 
 
186 STRUCTURAL GEOLOGY. 
 
 i. e., size; for the ratio between the floating mass of a body, or the surface 
 presented downward, and the mass of the body, increases with the diminu- 
 tion of a body. Then if the body is smaller, the ratio between the floating 
 surface and mass is larger; and hence comminution promotes flotation. If 
 this comminution is great, approaching complete or molecular comminution, 
 the velocity of the water again becomes a small factor, and the amount of 
 transportation chiefly depends on the containing capacity of the water ; but 
 as comminution is less and the size of the particles larger, some force must 
 intervene to promote flotation, and this is derived from the water power ; 
 and to sustain the same amount of flotation more of this force must be 
 utilized as the size of the particles increase. The amount of this force from 
 which must be drawn the supply in supporting flotation depends, cceterispar- 
 ibus, on the velocity or declivity, but practically the whole force is rarely 
 utilized. 
 
 The extent to which this force is utilized depends upon many complex 
 conditions by which the motion in the flowing water may be transmitted to 
 the load. To float, the particles of rock must be suspended in the water, and 
 as they fall from suspension during the process of transportation, they must 
 be resuspended, so that the water power must be used in lifting, and this is 
 done by the creation of secondary currents in regurgitation, eddying, boil- 
 ing, &c., or movements in the water transverse or oblique to the direction of 
 the flow, all of which impede the flow. If the flow is perfect no lifting can 
 be done ; so these secondary currents are produced by locally diverting the 
 flow from its normal course, and this diversion to secure lifting must be di- 
 rectly or indirectly upward ; the greater and oftener this diversion the more 
 lifting will be done. In other words, we may say that water power is ap- 
 plied to the lifting of the particles and thus promotes flotation by hetero- 
 geneity of flow, and this heterogeneity of flow is induced by the heterogeneity 
 of channel in both horizontal and vertical direction, but chiefly in the lat- 
 ter. And in obedience to well known laws of friction this heterogeneity of 
 flow is greatly increased by intensifying the flow, or in other words, increas- 
 ing the velocity of the water ; and velocity is due to declivity. And that 
 heterogeneity of channel, which by producing heterogeneity of flow utilizes 
 the water power in lifting the load, is also due to declivity ; and hence it 
 
DEGRADATION. 187 
 
 remains, first, that the water power, cceteris paribus, is a function of declivity ; 
 and, second, the" utilization of the water power, cceteris paribus, is a function 
 of declivity ; so that with a given amount of water and sufficient supply of 
 load, the rate of transportation through the agency of flotation depends on 
 declivity ; and the amount of transportation through driving also depends 
 on declivity. Therefore the rate of transportation of all mechanically com- 
 minuted matter is determined by declivity. 
 
 I have spoken of the containing capacity of water for load of the same 
 or less specific gravity than water, but the amount of such load is so minute 
 in comparison with the whole amount that we may neglect it. Again, I 
 have spoken of the containing capacity of water for particles of load of 
 greater specific gravity than water; the amount of matter transported in 
 this way is great, but usually the supply is so limited that the containing 
 capacity is rarely reached ; but it seems probable from observations made 
 on transportation of bad-land detritus that there are times when this con- 
 taining capacity is actually reached, when the amount transported is limited 
 by this condition, that is, containing capacity. Then what is this contain- 
 ing capacity ? In matter of this character without water the rock power 
 cannot overcome interstitial friction, and hence the matter is not transported. 
 In order that it may be transported by rock power it is necessary, first, that 
 the interstitial spaces shall be filled with water; and, second, that an amount 
 of water be added sufficient to reduce interstitial friction so that it may be 
 overcome by rock power. And it is possible that this can be determined 
 mathematically for particles of any given form, size and weight ; but in 
 nature these forms are multifarious, and the determination of the containing 
 capacity is a proper subject of experiment. I know of no such experiments 
 having been made ; but, from observations in nature, I am led to the con- 
 clusion that the containing capacity of water for particles of this nature is 
 at least three times its own weight. 
 
 Again I must remark that the last mentioned condition of transportation 
 is of very infrequent occurrence; and it remains, then, that in general trans- 
 portation, the rate is determined by declivity. 
 
 Having now examined the processes of disintegration and transporta- 
 tion separately, we will examine them as combined in the 
 
188 STRUCTURAL GEOLOGY. 
 
 METHODS OF DEGRADATION. 
 
 These are, first, erosion or degradation of the general surface; second, 
 corrasiori or degradation of the stream channels ; and, third, sapping or deg- 
 radation of cliffs. 
 
 EROSION. This is distributed over the general surface; the rocks are 
 disintegrated by climatic agencies and transported into streams by the wash 
 of rains, both by driving and flotation, and flotation is largely promoted by 
 the beating of rains. In this method the rate of degradation depends on the 
 rate of transportation. This is a fact of almost universal observation; for 
 wherever there is soil or loose earth, the amount of such matter is the excess 
 of disintegration over transportation. 
 
 We have already seen in the former analysis of transportation that 
 with a given quantity of water, transportation will depend on declivity, but 
 in the transportation belonging to this method of degradation the quantity 
 of water is a factor of transportation only to a limited extent, for increased 
 rainfall promotes the growth of vegetation which serves as a protection to 
 the soil. Nor is this protection inconsiderable, for it preserves the rocks 
 from the beating of the storms, and prevents the waters from gathering rap- 
 idly into rills and brooks, and strains the water of its earthy sediments. I 
 have many times witnessed the action of a - storm in an arid region where 
 the disintegrated rocks were unprotected by forests, shrubbery, or turf, and 
 as often have I been impressed with the wonderful power of the infrequent 
 storm to gather up and carry away the land, as compared with the frequent 
 storm in the prairie or forest of a land more richly clad. The same contrast 
 may be observed in a region brought under the dominion of man by culti- 
 vation where the surface of a plowed field is swept away by a storm, and 
 the furrows are the channels for floods of mud, while the meadow receives 
 the rain with outstretched arms of verdure, which bear it gently to the earth, 
 where it is gathered into quiet rills, which feed a stream made turbid it is 
 true, but pure when compared witli the stream of mud flowing from the field 
 from which the plowman was driven by the storm. 
 
 Erosion, then, or surface degradation is not greatly promoted by 
 increased rainfall, and it may be that its effect is rather to retard the pro- 
 
DEGRADATION. 189 
 
 cess; but the difference between greater or lesser rainfall is plainly manifest 
 in the topographic features produced little rainfall giving angular reliefs ; 
 much, rounded reliefs. 
 
 Neglecting such a hypothetic condition as no rainfall, we have in nature 
 to consider only greater or lesser raiiffall. With greater rainfall we have a 
 greater power, but a lesser utilization of the power; with lesser rainfall we 
 have lesser power, but greater utilization; and in these varying conditions, 
 just where maximum degradation is found I am not able to state. Hence, 
 in the process of degradation which. I have called erosion, we have simply 
 to consider declivity, with exceptions so minute that they may be neglected. 
 
 Now, it must be taken into consideration that this is the most import- 
 ant method of degradation, as it acts everywhere on the dry land; but, 
 because its operations are so greatly diffused, being universal in its action 
 on dry land, it is so subtle and minute in its manifestations within any area 
 which may come immediately under the eye that its efficiency is apt to be 
 underrated. 
 
 CORRASION. This is the action of waters gathered into streams where 
 their operations are confined to more limited areas, that is, along the chan- 
 nels of such streams. Here the material supplied from the surrounding 
 surfaces by erosion is further transported by the streams, and in the process 
 of transportation becomes the instrument used in disintegrating the stream 
 beds; and the material thus disintegrated is added to that furnished by ero- 
 sion, and with it is transported by the streams, and this added material also 
 becomes an instrument of disintegration. 
 
 The force used in disintegration is rock power and water power; load 
 is the instrument, water the agent. All processes of solution are neglected. 
 
 The force of rock power and water power is measured by mass into 
 fall, and this may be considered as declivity; the specific gravity of the 
 instrument not being greatly variable may be neglected. There are other 
 conditions of instrument, such as hardness and angularity of particles, which 
 for any given particle might be of value in determining its efficiency; but, 
 in the multifarious particles of diverse hardness and form, a general average 
 will be established for streams, variable within such small limits that these 
 conditions also may be neglected. The only condition of instrument of 
 
190 STRUCTURAL GEOLOGY. 
 
 sufficient importance to be considered in this connection is size of particles, 
 for the utilization of the particles as instruments is dependent, cceteris paribus, 
 on their size. If the particles be too large they cannot be transported, arid 
 thus cannot be used as instruments; and within the limits of size transported, 
 a greater amount of instrument will fae used as the size of the particles 
 diminish; that is, witli a given stream, the instrument is increased with com- 
 minution of instrument, the instrument being the load, and load being 
 increased by comminution as has been seen. 
 
 We have next to consider the beds to be corraded, and so far as their 
 constitution is a factor in corrasion, it may be brought into the simple 
 expression that heterogeneity promotes corrasion. But a part of the instru- 
 ment of corrasion is derived from the rocks corraded; and as heterogeneity 
 of these rocks promotes disintegration, and to the same extent promotes corra- 
 sion, it further augments the instrument of corrasion in the channel below. 
 But it has been seen that in transportation the utilization of the water power 
 in promoting flotation as a function of heterogeneity of flow is a function of 
 declivity cceteris paribus. Hence, declivity not only increases the force, but 
 it also utilizes the force, and, hence, multiplies itself as a factor of corrasion. 
 A part of the instrument in corrasion is the load of the stream derived from 
 erosion; and we have already seen that the amount of this load depends 
 chiefly upon declivity $ hence, the amount of instrument from this source 
 depends on declivity of erosion, and the amount of instrument derived from 
 corrasion depends on declivity; and the power of corrasion, that is, rock 
 power plus water power, depends on declivity. Hence, with a given quan- 
 tity of water and a given character of bed, rate of corrasion depends on 
 declivity. Again, rapid corrasion increases the declivity of erosion,^: and 
 hence increases erosion; and this increased erosion augments the instru- 
 ment of corrasion, hence, increases corrasion; and declivity by the two 
 methods of degradation enters the general problem of degradation as a factor 
 with a rapidly increasing value. 
 
 Corrasion is a very important method of degradation, although its results 
 are of much less magnitude than those of erosion. The evidence of this can 
 be seen, and the results often strike the student of physical geography with 
 great force. The deep channels in which the rivers run are grand topo- 
 
DEGEADATION. 191 
 
 graphic features. Deep river valleys and mountain gorges are everywhere 
 seen to have been produced by this agency, and the power of the streams in 
 carving their winding paths is readily comprehended. But the magnitude 
 of this agency is more thoroughly brought into visual comprehension in the 
 caiions that traverse the Plateau Province, for here erosion has not kept pace 
 with corrasion. All the processes of erosion and sapping serve to obliterate 
 the evidences of corrasion, and the latter appears more plainly as its pro- 
 gress exceeds that of the other methods; but still the evidences of corrasion 
 rarely disappear until the land is buried by the sea; for wherever an area of 
 land is above its base level of degradation, there corrasion will be manifest 
 by deepening its channel; and wherever the dry land has been brought 
 down near to its base level, there corrasion is manifest by widening its 
 channel. 
 
 There is another method of degradation to be considered, viz : 
 SAPPING. The walls that inclose the channels of corrasion are broken 
 down by gravity, and when in the progress of corrasion the channel of a 
 stream reaches beds which easily disintegrate, having passed through beds 
 which disintegrate but slowly, degradation is increased by an undermining 
 process, and as corrasion still continues through a series of yielding and 
 unyielding beds, the walls of the streams are carried back in a series of steps, 
 the tread of each step being the summit of a harder bed, the rise of each step 
 the escarped edge of the harder bed above, underlaid by the softer. It is 
 manifest that the conditions favorable to the continuatiorh of this cliff degra- 
 dation to any great distance back from the stream are found only where the 
 beds are horizontally, or nearly horizontally stratified. But sapping is not 
 confined to the undermining of walls produced by corrasion, but is carried 
 on in simple anticlinal upheavals from the axis toward the flanks; in up- 
 heavals of the Uinta type, in like manner, and in the blocks displaced as 
 integers, like those in regions having the Kaibab and other structures, from 
 the elevated to the depressed portions. In these cases the cliffs are produced 
 by the unequal erosion of harder and softer beds wherever upheaval exceeds 
 degradation, and climatic conditions are favorable; and, further, this sap- 
 ping process is carried on in regions of great declivity, where deep channels 
 of corrasion are formed, whatever may be the petrologic conditions, the 
 
192 STRUCTURAL GEOLOGY. 
 
 alternation of softer and harder beds not being an absolute, but only an 
 accessory condition. In those mountain regions where the rocks are granites, 
 schists, or extravasated masses, every little stream engaged in deepening its 
 channel furnishes conditions favorable to sapping; and so these walls are ever 
 yielding, in small fragments that tumble down from time to time, in large 
 fragments when cliffs or crags topple over, and in great masses by land 
 slides. So wherever cliffs are formed, whether by deep corrosion or unequal 
 erosion, the cliffs themselves are degraded, disintegration beginning with the 
 breaking of the rocks above through atmospheric causes, aided by gravity. 
 Then the rocks are transported by gravity from the higher to lower levels 
 when the disintegration is increased by the fall, and the rocks are left in a 
 condition to be readily transported by the wash of rains or the flow of 
 streams. 
 
 The extent to which degradation is carried on by this sapping though 
 much less than either of the others, is so great that it must not be neglected 
 in any consideration of this subject. 
 
 In a mountain region every stream forms cliffs by deep corrasion, and 
 every cliff has a talus in evidence of the efficiency of this method, and we 
 see its effects exhibited in the most remarkable manner in the long lines of 
 cliffs or towering escarpments which stand athwart the Plateau Province. 
 
 In this method of degradation petrologic conditions may be more or 
 less favorable, but within these conditions the principal factor in determin- 
 ing rate of degradation is declivity. The declivity must be very great for 
 the initiation of the process. With rocks already disintegrated by atmos- 
 pheric agencies, the declivity must be greater than what is usually denomi- 
 nated natural slope ; that is, it must be so great that rock power can Over- 
 come friction so as to transport the material to a lower level ; and again, 
 that gravity may be used as a force of disintegration, the declivity must be 
 still further increased, and with this increase of declivity the rate of dis- 
 
 t/ 
 
 integration and transportation by falling is increased at a great ratio until 
 the rocks are undermined, when the conditions again multiply the power. 
 But rapid corrasion, which depends on declivity, increases sapping ; and 
 sapping, which depends on declivity, increases corrasion by adding to the 
 
DEGRADATION. 193 
 
 instrument of corrasion, and again declivity is multiplied as a factor in 
 degradation. 
 
 To this rule that sapping promotes corrasion by adding to the instru- 
 ment of corrasion, there are three curious exceptions, one of which is of 
 great importance. The first is where the cliff produced by deep corrasion, 
 before it has retreated from the bank of the stream, tumbles down so as to 
 choke the stream. In this case the material falling from the cliffs serves to 
 protect the underlying stream bed, and, so far as it ponds the water up stream, 
 it causes it to precipitate its load, and thus deprives it of the instrument of 
 corrasion. But this fallen matter is rapidly attacked by the stream, is 
 soon taken up as load, and used as an instrument of corrasion. 
 
 The second exception is where a lateral stream enters a main one, the 
 lateral stream having so great a declivity as to be able to transport great 
 quantities of coarse material during local flood time, or that flood time 
 which pertains to the secondary stream, but not to the primary. In this 
 case it may sweep along its greatly -inclined bed into the main channel, 
 load derived from sapping, or even from erosion, which cannot be farther 
 transported by the main stream, and this new matter for the time being 
 serves as a protection to the bed of the main stream. In the Colorado 
 River, with very few exceptions, all the falls and rapids which beset its 
 course through the great canons are caused by dams made by side streams 
 having great declivity. A few of the falls are made by dams formed by the 
 sapping of the immediate cliffs of the main river. 
 
 The third exception is found where streams having great declivity run 
 through beds of incoherent sands. Here load is rapidly added to the stream 
 by gravity, and the stream not being confined by water tight rocks, its 
 Abaters penetrate the interstitial spaces of the sands and serve to overcome 
 the friction of slope, and thus assist rock power in transporting the sand 
 into the stream. Here the stream cannot have high banks, and the channel 
 is greatly widened and is engaged in transporting load furnished it from the 
 sides, and can make but little progress in corrasion, for every particle car- 
 ried from the bottom of the stream is rapidly replaced by one from the 
 sides. This condition is finely illustrated in many places along the course 
 of the Virgin River, a tributary of the Colorado. In one place where its 
 13 P G 
 
194 STRUCTURAL GEOLOGY. 
 
 course is through indurated and homogeneous rocks, its channel is from 20 
 to 50 feet in width, and from 1,500 to 3,000 feet in depth; it runs through 
 a narrow but profound gorge. But when it passes a well defined geologi- 
 cal horizon from these coherent into extremely incoherent beds, its channel 
 abruptly widens, and the stream is a broad sheet of water many hundreds 
 of yards in width and but a few inches in depth. Again this condition is 
 well illustrated in the Platte River where it crosses the Plains. Here the 
 beds through which the river runs are incoherent, and although the river 
 has as great a fall as the Colorado through the plateaus, and although the 
 climatic conditions are essentially the same, yet the former runs in a broad 
 sheet scarcely below the level of the plain, while the latter runs in a narrow 
 groove at profound depths below the general surface. Thus it is that the 
 streams, though they may have great fall, and though the stream beds may 
 be of material that can be rapidly transported, yet they do not succeed in 
 excavating deep channels, for every particle taken from the bottom is re- 
 placed. Nevertheless general degradation is carried on by such streams at 
 a rapid rate, but not at a maximum rate, for the water permeating the sands 
 on either side is steadily and rapidly evaporated, and is thus lost as an agent 
 of degradation. There are many streams in the arid region of America, 
 running alternately through harder and softer beds, which are continuously 
 degrading the coherent rocks and intermittently degrading the incoherent 
 rocks ; that is, the streams are ever living where the beds are coherent, but 
 when they reach the sands the waters sink and re-appear where the beds 
 below are harder. Through these harder beds the streams caflon, and 
 through the softer beds low plains stretch either way from the course of 
 the stream ; ' and it is only during flood time that the channels are cut across 
 these plains from canon to cailon. 
 
 But dropping these exceptions, all of them interesting cases, let us return 
 to the main argument. We have seen that ever are the effects of declivity 
 in degradation multiplied directly and indirectly. Wherever the rate of 
 degradation by any one method is increased it is due chiefly to increased 
 declivity, and wherever the rate of one method of degradation is increased, 
 the rate of all other methods is increased. 
 
 We may not be able to give mathematic expression to rate of degrada- 
 
DEGRADATION. 195 
 
 tion in terms of declivity, but Hopkins arid Babbage have shown that the 
 power to transport load of a given size of particles increases with the sixth 
 power of the velocity of water, and it is probable that the rate of degrada- 
 tion increases with the velocity of water in very nearly the same ratio, but 
 modified slightly by a multiplicity of climatic and petrologic conditions. 
 
 It will be seen that in the above discussion I have neglected one term 
 of climate, that is temperature. My field of study has been limited, to the 
 frigid and temperate climates, and for the effect of a torrid climate I have 
 no facts to guide me to valid conclusions, but within my field of study the 
 temperature term, though modifying the methods and topographic results of 
 degradation, does not invalidate the result I have reached as to the over- 
 shadowing importance of declivity. Increased cold diminishes the protec- 
 tion derived from vegetation and permits greater rainfall to produce greater 
 degradation. But in a given latitude increased cold is due to increased ele- 
 vation. (This increased elevation is also increased declivity.) But this i& 
 again modified by the fact that moisture descends as snow, and to that extent 
 the beating power of rains is lost. Where these snows accumulate as ice, 
 forming glaciers, another modification of degradation is introduced, dimin- 
 ishing the effects of the water in degradation and changing the topographic 
 features; that is, any given amount of precipitation of water will produce 
 more degradation acting as rains and rivers than as snows and glaciers. By 
 the former condition atmospheric disintegration is more rapid, and corrasion 
 is confined to narrower channels, and thus sapping is promoted. Transporta- 
 tion in ice and water are governed by the same conditions of flotation, and 
 the greater heterogeneity of river channel promotes greater flotation, so that 
 degradation in each of its elements of disintegration and transportation is 
 faster by rains and rivers than by snows and glaciers. Hence, as cold 
 increases, degradation is promoted by the decrease of protection derived 
 from vegetation until that degree of cold is reached where the moisture is 
 precipitated as snow, when low temperature serves to decrease degradation. 
 
 Having considered all the modifying conditions of climate and petrol- 
 ogy, it yet remains . that degradation increases with declivity through the 
 combined forces of water power and rock power in a rapidly-multiplying 
 rate from that low degree of declivity which permits the transportation of 
 
196 STJRUCTUKAL GEOLOGY. 
 
 finely-comminuted load to that high degree of declivity which permits, the 
 load to be moved by its own gravity, when the effect of declivity is again 
 multiplied at a still higher rate until vertically is reached and undermining 
 begins and another multiplication of the effect of declivity ensues. 
 
 There are conditions of degradation in the extremes of declivity worthy 
 of mention. In high degrees of declivity transportation in a horizontal 
 direction is limited, the cliffs soon tumble down, and degradation by this 
 process ceases. In a very low degree of declivity approaching horizontally 
 the power of transporting material is also very small. The degradation of 
 the last few inches of a broad area of land above the level of the sea would 
 require a longer time than all the thousands of feet which might have been 
 above it, so far as this degradation depends on mechanical processes that 
 is, driving or flotation; but here the disintegration by s.olution and the 
 transportation of the material by the agency of fluidity come in to assist 
 the slow processes of mechanical degradation, and finally perform the chief 
 part of the task. 
 
 We may now conclude that the higher the mountain, the more rapid its 
 degradation ; that high mountains cannot live much longer than low mount- 
 ains, and that mountains cannot remain long as mountains ; they are ephem- 
 eral Topographic forms. Geologically all existing mountains are recent; 
 the ancient mountains are gone. But existing mountains may be old or 
 young as compared with other existing mountains. We may speak of the 
 age of mountains, referring to the age of the rocks of which they are com- 
 posed, but this will have no reference to the age of the mountain form. We 
 may speak of the age of a mountain with respect to the inception of the up- 
 heaval which exposed the rocks to that degradation which has produced the 
 mountain form; and this epoch will not be very long ago, geologically, for 
 the rate of upheaval must be greater than the rate of degradation, else 
 mountain forms will not be produced. We may speak of the age of mount- 
 ains, referring to the completion of the upheaval by which the mountain 
 forms were produced through degradation ; the time which has elapsed since 
 the epoch to which we then refer must be short indeed; but if, in speaking 
 of the age of mountains, we refer to the time when those topographic forms 
 were produced, they are all newly born. 
 
DEGEADATIOK . 107 
 
 
 
 Having found that degradation is accelerated by increased declivity at 
 a high rate, let us apply this law to the degradation of the Uinta uplift and 
 see what topographic features would have been produced if the uplift had 
 been abrupt or greatly faster than degradation. As the area was uplifted 
 in large part as an integer, its steep flanks would then have been regions of 
 great declivity, while its axial region would have comparatively gentle slopes, 
 and as the first streams heading along the axis ran toward the flanks, these 
 streams would not only have had channels suddenly increasing in declivity 
 at the flanks, but the amount of water carried by the streams would have 
 steadily increased from axis to flanks, and hence corrasion on the flanks 
 would have proceeded at a rate determined by these multiplied causes. As 
 the main channels were thus corraded all the lateral channels would in like 
 manner have been rapidly corraded ; this would have induced rapid sapping 
 and rapid erosion, and the degradation along the flanks would have far 
 exceeded degradation along the axis, and this would have resulted in the 
 production of an ever narrowing axial ridge. An examination of the map 
 reveals the fact that these are not the topographic characteristics of the 
 Uinta Mountains. The axial region is higher in the western portion of that 
 part of the range under consideration, but the difference in elevation 
 between the flanks and axis is inconsiderable when compared with the whole 
 amount of degradation; while in the eastern portion of the part of the range 
 under consideration the axial region is much lower than the flanking region 
 on either side. Here the excess of degradation in the axial region is 
 accounted for by remembering that the degradation of consequent drainage 
 has been assisted by the degradation resulting from extra limital or through 
 drainage. But in the former case, i. e., the western portion of the region 
 under consideration, the drainage is all consequent on the upheaval, and to 
 account for the plateau like character of the region, we have to suppose 
 either that the elevation being constant has been but little faster than 
 degradation , or else that elevation has been intermittent. 
 
 O ' 
 
 Let us further consider these two hypotheses, one of which must be 
 true. If elevation was constant but slow, the axial region was first attacked 
 by degradation, and as it was slowly uplifted, degradation kept this axial 
 
198 STRUCTURAL GEOLOGY. 
 
 
 
 region down so that an axial ridge was not produced. If elevation was 
 intermittent it might have been fast for a time, and then ceased until the 
 region was planed down to a general level now represented only by the 
 summits of the highest peaks, and then a new upheaval carried it to its 
 present elevation. But the rate of this last uplift must have been slow or 
 the axial ridge would have been more pronounced, and hence we may infer 
 that the elevation was either slow by continuous motion, or what would be 
 its equivalent, slow through intermission of movement, with the last epoch 
 of elevation slow. Further light will be thrown on this subject when we 
 consider sedimentation. It is manifest that if elevation was slow so that 
 degradation progressed nearly as fast as displacement, then degradation was 
 slow. Again consider the amount of degradation. From this portion of 
 the Uinta range a block three and one-half miles in thickness has been 
 carried away, all since the close of Mesozoic Age ; and for this degradation 
 the declivity was small so that its progress was slow, and we have some 
 conception of the amount of time which has elapsed since the beginning of 
 the Uinta upheaval. 
 
 SCHOLIUM. 
 
 Let us now turn aside for a moment from the main argument to consider 
 a statement which I have elsewhere made concerning the Basin Ranges. These 
 are monoclinal ridges of displacement, of narrow base and steep declivities 
 where conditions for rapid degradation obtain, but the amount of degrada- 
 tion of any Basin Range is exceedingly small as compared with the Uinta 
 Range, and we are forced to conclude that the epoch of its upheaval is much 
 later than that of the inception of the Uinta uplift, but may be of about 
 the same date as the last throw of the Uinta displacement. 
 
 SEDIMENTATION. 
 
 Soon after the inception of this upheaval, sedimentation began on either 
 flank and continued during the progress of the uplift until on the north 
 side more than 6,000 feet of sandstones and shales had been deposited, and 
 where the Brown's Park beds overlap Bridger beds about 8,000 feet. On 
 the south side also there was a great accumulation, the extent and charac- 
 
SEDIMENTATION. 199 
 
 teristics of which are not yet fully known. Geologists will understand that 
 the thicknesses given refer only to the beds which remain to be studied. 
 There may have been much greater sedimentation ; beds may have been 
 formed during periods of sedimentation which were carried away during 
 periods of dry land conditions, and especially during the last great period 
 of degradation not yet ended, and of which sediments there are no residuary 
 fragments attesting to their former existence. 
 
 On both sides of the range, but especially to the north, we know that 
 the progress of sedimentation was interrupted by periods of dry land con- 
 ditions. These dry land conditions prevailed over a large area during the 
 epoch separating the Lower Green River from the Bridger period, but a 
 part of this interval of time at least was occupied in sedimentation over a 
 portion of the great lacustrine area. Again, a period of dry land con- 
 ditions prevailed between the deposition of the Bridger and the Brown's 
 Park Groups. The latter was deposited over areas in the region of uplift 
 beyond the reaches of the antecedent lakes represented by the four lower 
 Cenozoic groups. How far the Brown's Park Lake extended over the region 
 which had previously been occupied by the waters in which the earlier 
 Tertiary sediments were deposited we do not know. Wherever the overlap 
 of the Brown's Park beds on the Lower Cenozoic groups has been studied 
 the former terminate in escarpments, and no evidence of shore line has been 
 seen. The Bishop Mountain Conglomerate which has been found to lie uncon- 
 formably on all the other geological formations of this region, except the 
 Brown's Park, and possibly on this latter also, is neither a marine nor 
 lacustrine deposit, but is believed to be a subaerial gravel. It is possible 
 many geologists would ascribe it to the action of ice, but in any case it need 
 not be considered in our account of sedimentation. 
 
 Such were the general changes from emergence to submergence through- 
 out the region of downthrow, but there was a narrow belt of country between 
 the general region of uplift and the general region of downthrow which 
 was subject to more frequent changes than the greater ones described above. 
 
 We find, first, that there are many overlaps, i. e., that later beds extend 
 beyond the limits of earlier beds. To accomplish this result it is manifest 
 that the waters of the lakes must have risen or the land subsided. Again, 
 
200 STEUCTUEAL GEOLOGY. 
 
 we find that certain beds thin out shoreward. It is manifest in this case 
 that the waters of the lakes must have fallen or the land have risen. Again, 
 we find upper lake beds unconformable on lower lake beds. Here it is 
 manifest that a dry land period separated their deposition, and that displace- 
 ment occurred. These outthinnings, overlappings, and unconformities 
 appear from time to time from the base to the summit of all the fresh water 
 beds older than the Brown's Park. 
 
 There are some other interesting facts relating to the belt under con- 
 sideration, viz, the appearance of many conglomerates which are rapidly 
 changed into sandstones in a direction farther from shore. These conglom- 
 erates are found to be made up of the more or less water-worn fragments of 
 limestones, sandstones, and quartzites similar to those outcroppings in the 
 mountain region or area of uplift, and often contain the same fossils, leading 
 us to conclude that they are derived from that region. 
 
 It should be remarked here that the appearance of these conglomerates, 
 together with the overlappings, outthinnings, and unconformities before 
 mentioned, furnish the evidence on which we decide that this was the old 
 shore-line, and that the lake beds were never continuous over the great 
 Uinta area. On the other hand, the fact that no such phenomena have been 
 observed in the outcroppings of the Mesozoic and Paleozoic beds leads us to 
 conclude that they were at one time continuous over the Uinta area, and 
 this is strengthened by the fact that in all these lower groups any bed found 
 on the one flank re-appears on the other with all its lithologic character- 
 istics; and it is thus that we fix the epoch of the inception of the Uinta 
 upheaval after the close of the deposition of the Upper Hogback Sandstone 
 of the Point of Rocks Group, and before the deposition of the lowest bed 
 of the Bitter Creek formation. 
 
 Returning again to the consideration of sedimentation in the region of 
 downthrow in its relation to displacement and degradation in the region of 
 uplift, we have first to consider the amount of sedimentation or building up 
 of the sediments on the flanks of the uplifts to the extent of many thousand 
 of feet ; next, the general unconformities which separate some of the forma- 
 tions ; and, lastly, the minor unconformities, overlappings, and outthinnings 
 observed in the zone of ancient shore-lines. From all these facts it appears 
 
UINTA MOUNTAINS RECAPITULATION. 201 
 
 that displacement, degradation, and sedimentation were in a general way 
 simultaneous and continuous up to the close of the Bridger period, but 
 interrupted by many minor cessations in the progress of displacement and 
 some cessations in the progress of deposition, and that between the Bridger 
 and Brown's Park periods there was a long time when no sediments were 
 accumulated. 
 
 The Uinta uplift in the region of Brown's Park was at one time several 
 thousand feet greater than we have represented it to be, but after the deposi- 
 tion of the Brown's Park beds it fell down that much ; the evidence of this 
 will more fully appear when we have discussed the Yampa plateau, Diamond 
 Peak, the Dry Mountains, and Brown's Park. 
 
 RECAPITULATION. 
 
 We will now recapitulate some of the important conclusions reached 
 in the study of the geology of the Uinta Mountains. First, the upheaval 
 began at the close of the Mesozoic Age, and continued with slight intermis- 
 sions until after the Bridger period, and the total amount of upheaval in the 
 axial region was more than 30,000 feet. The region was upheaved partly as 
 an integer and partly as a body of minute parts. Second, pari passu with 
 upheaval degradation progressed, and in some places along the axial portions 
 of the region this degradation amounts to more than 25,000 feet, and the 
 mean degradation is three and one-half miles, and from the entire area there 
 has been a total degradation of 7,095 cubic miles. While we have no 
 means of determining any absolute rate of degradation, we are led to con- 
 clude that a maximum rate was not established ; that, as upheaval was slow, 
 degradation was slow. Third, pari passu with displacement and degrada- 
 tion in the region of uplift, there was sedimentation in the region of down- 
 throw. This sedimentation was sometimes intermittent over large areas, 
 frequently intermittent along the shore-line zones. These sediments were 
 derived in part at least from the region of uplift, but probably mingled with 
 materials brought from districts not embraced in the region under discussion. 
 On the north side of the mountains the amount of sedimentation was more 
 than 6,000 feet, and where the Brown's Park beds overlap Bridger beds the 
 amount of sedimentation was about 8,000 feet. 
 
202 STKUCTUKAL GEOLOGY. 
 
 THE YAMPA PLATEAU. 
 DISPLACEMENT. 
 
 The structural sections of Plate I embrace not only the Uinta Mountain 
 region, but also extend over the region which I have designated as the Yampa 
 Plateau. The facts relating to the present position of the formations are 
 there fully set forth. On Plate V we have separated the stereogram of the 
 Yampa region from the general stereogram, Plate III. Referring to Plate 
 V, attention is called to the Island Park sag d, d, to the Echo Park sag e, 
 to the Split Mountain cusp c, to the monoclinal flexure of Cliff Creek m, m, 
 w, to the Fox Creek flexure f, and to the Yampa fault #, g, which branches 
 midway in its course. 
 
 A comparison of 'this stereogram with the geological map will be 
 instructive. 
 
 The Yampa Plateau is on the south side of the Uinta Mountains, and 
 all the lines of displacement in the stereogram, except the Y ampa fault, show 
 the upheaval to be northward corresponding to the general upheaval of the 
 Uinta Mountains, but the exception mentioned exhibits a northward throw. 
 This great displacement is a flexure at its eastern end ; but it finally 
 changes into a dragged fault, where the thrown beds are flexed upward at 
 the end, and then into a clean fault ; midway in its course it branches ; the 
 northern branch is a fault as far as it has been traced ; the southern branch 
 changes from a fault to a monoclinal flexure, and finally these branches of 
 the great displacement fade out, but in a manner not clearly understood, as 
 the region is marked by an accumulation of late subaerial gravels, by soil 
 and by vegetation, and on the stereogram this uncertain area has been rep- 
 resented by broken lines. By referring to the map it will be seen that the 
 main fault with its branches is represented in the topography of the country 
 by bold cliffs. These lines of cliffs are broken by many deep gorges of 
 corrasion descending from the plateau to the lowlands where the stratigraphy 
 is plainly revealed, and the lower beds of Triassic sandstone are seen on 
 the same geographic level as the upper beds of Uinta Sandstone, so that the 
 total displacement is about 5,000 feet. These cliffs are due immediately to 
 
THE YAMPA PLATEAU. 203 
 
 displacement ; where this displacement is by faulting the cliffs are escarp- 
 ments, but where it is by flexure the flexed beds remain, and the slope of 
 the cliffs conforms in a general way with the dip of the strata. Hence these 
 lines of cliffs have not receded from the locus of displacement, although they 
 are so precipitous as so furnish conditions favorable to rapid degradation by 
 direct sapping, corrasion, and general erosion. From these facts we inevi- 
 tably conclude that the displacement is of late date. But the Triassic beds 
 on the upheaved side are gone, and in many places a great thickness of 
 Carboniferous beds also, while on the thrown side a notable thickness of 
 Trias yet remains. The non-recession of the cliffs proves that the displace- 
 ment was not ended long ago, if indeed the movement has yet ceased, while 
 the occurrence of the beds on the thrown side, which have been degraded 
 from the upheaved side, lead us to refer the inception of the upheaval to an 
 epoch of much earlier date, and to infer that the displacement was slow, yet 
 not so slow that degradation was able to keep apace. 
 
 When we come hereafter to discuss the relation of this displacement to 
 Other facts of displacement, degradation, and sedimentation, it will appear 
 that this displacement was not upheaval in relation to the general region 
 under discussion in this chapter, but was in fact downthrow, whatever it 
 might have been in relation to the level of the sea or in that other relation, 
 which yet may be a very different thing, i.e., to the center of the earth. 
 
 SCHOLIUM. 
 
 Early in this volume I distinctly defined my use of the terms "upheaval" 
 "subsidence," "uplift," and "downthrow," and restricted the meaning of these 
 words in such a manner that they should relate only to adjacent and compared 
 beds of rock, but I recognize three categories of relations that may be 
 expressed by these terms, viz, the relation of parts of a geological horizon 
 to each other, the relation of parts of a geological ho'rizon to the level of 
 the sea, and the relation of parts of a geological horizon to the center of 
 the earth. For these several categories it would be a great advantage to 
 geological science, by leading to greater simplicity and precision of de- 
 scription and to clearer conceptions, if different verbal representatives could 
 be used for the different ideas. 
 
204 STRUCTURAL GEOLOGY. 
 
 DEGKADATION. 
 
 The amount of degradation in the region of the Yampa Plateau though 
 less than in the Uinta region as denned above, is still great. The maximum 
 degradation is found at the few points where deep canons cut the cliffs of 
 the Yampa fault, and Uinta Sandstone is found in the floor. In these places 
 there has been more than 15,000 feet carried away since the close of 
 Mesozoic time ; the mean degradation over the entire area has been 8,000 
 feet, or a little more than one and a half miles, and the total more .than 
 
 1,200 cubic miles. 
 
 SEDIMENTATION. 
 
 A part of the rock material taken from this region was doubtless 
 deposited in the Tertiary lake region to the south, another portion probably 
 into the BroAvn's Park Lake, and still another and very considerable portion 
 has been carried away by the Colorado River to the distant sea. 
 
 JUNCTION MOUNTAIN. 
 
 This district was studied in the earlier years of the exploration of the 
 region, and since that time it has not been carefully reviewed. In my notes 
 I make mention of a fault running in a north and south direction to the east 
 of the axis of upheaval, with a throw to the westward, but the magnitude 
 and general characteristics of the fault are not given. The sections given 
 in Chapter I of this volume, figures 1 and 2, represent the idea of its structure 
 obtained at the time it was studied, but subsequent years of observation in 
 other regions lead me to place no great value on the observations made 
 and conclusions reached at that time. 
 
 DIAMOND PEAK. 
 
 To the north of 0-wi-yu-kuts Plateau is Diamond Peak. The principal 
 mass of the mountain is on the north side of the great Uinta fault, but the 
 foot of the mountain stretches across from the thrown to the upheaved side 
 of the fault. 
 
 For a long time this mountain was an enigma. From its position it 
 
DIAMOND PEAK. 
 
 ought to be a monoclinal ridge, but it is not. Again, its base rises chiefly 
 from the thrown side of the fault, but its summit rises many hundreds of 
 feet higher than the plateau on the upheaved side of the fault, and it seems 
 to stand as a contradiction to all known laws of the progress of degrada- 
 tion. On a first visit to the mountain no clew to this enigma was obtained ; 
 on a second visit a better understanding of its lithologic constitution was 
 obtained; and on a third and final visit, which was somewhat protracted, it 
 is believed that the problem was solved. 
 
 All that portion of the base of the peak north of the fault is composed 
 of beds of the Bitter Creek period lying horizontally. On the horizontal 
 beds sandstones and limestones are piled in confusion. In the sandstones 
 no fossils were found, but they resemble lithologically the sandstones of 
 Carboniferous Age. The limestones contain Carboniferous fossils. We 
 have in fact a huge pile of Carboniferous rocks resting on a base of horizon- 
 tal Tertiary sandstones. Now to explain how rocks of an older horizon 
 were piled on a later, w^e have a fact which was discovered after the second 
 visit, but before the third, viz, that there had been two movements along 
 the line of this fault in opposite directions. By the first movement the 
 Uinta or upheaved side was earned about 3,000 feet higher in relation to 
 the beds on the north side than now appears. Subsequently by a reverse 
 movement it fell back the 3,000 feet. After the former displacement and 
 before the latter, we may reasonably suppose that here a great cliff faced 
 northward, for the total displacement by faulting was.about 23,000 feet, and 
 the only hypothesis necessary to the explanation of such a line of cliffs is that 
 displacement was in its later development faster than degradation. Such 
 cliffs would rapidly tumble down, and beds of Carboniferous Age might 
 thus be placed on beds of Tertiary Age. But further, immediately to the 
 west and immediately to the east along this zone of displacement, the line 
 of faulting in its meanders back and forth through the zone of flexure, 
 which has heretofore been described, passes some distance from the upheaved 
 side of the zone toward the thrown side, and hence the beds on the upheaved 
 side dip at a great angle to the northward, and are in a position to more 
 readily tumble down, and doubtless this condition obtained where the 
 
200 STRUCTURAL GEOLOGY. 
 
 0-wi-yu-kuts cliff overhung the Tertiary sandstones that form the base of 
 Diamond Peak. 
 
 This double movement along the plane of the Uinta fault is seen 
 farther west beyond Red Creek, where it was first discovered, and where 
 the sandstones of the Point of Rocks period are found to have been 
 dragged down by the later arid southward throw. Similar evidences are 
 seen farther eastward, between Diamond Peak and Red Creek, and the 
 topographic features of the region in like manner give evidence of the 
 later movement, for some of the peaks composed of Bitter Creek sand- 
 stones are higher than the mountains and plateaus of quartzite and Uinta 
 Sandstone. To the east of Diamond Peak this second displacement did 
 not follow the old plane of faulting, but trended irregularly northward 
 and bent downward the edges of the beds which originally abutted against 
 the southern wall of the fault, which was composed of Uinta Sandstone and 
 underlying rocks. Subsequent degradation has earned away the upper 
 part of these beds that were turned down, and we now see fragments 
 standing on edge and the younger beds are on the south side, the older 
 beds on the north side, a fact which I have stated in a former chapter, and 
 which is thus explained. But we have still further evidence of this later 
 throw on the south side. The beds of the Brown's Park Lake were 
 deposited against the foot of Diamond Peak, and this later displacement 
 was subsequent to the deposition of these beds, and the plane of faulting 
 cuts them in twain. Those fragments on the north side of the fault lie 
 high upon the side of Diamond Peak, while the beds on the south side of 
 the fault are low down in the valley at the foot of the peak. The latter 
 are nearly horizontal ; the former have a general dip southward, but are 
 broken and greatly contorted. 
 
 This mountain, of origin so strange, was curiously enough the scene 
 of the great diamond bubble, so skillfully burst by my brother geologist, 
 Clarence King. 
 
 THE DRY MOUNTAINS. 
 
 This low range of mountains extends in a southeasterly direction from 
 Vermilion Creek to the Snake River, and, topographically, appears to be a 
 
THE DKY MOUNTAINS. 207 
 
 continuation of the great monoclinal ridge of Carboniferous sandstone north- 
 east of Po Canon, but, in fact, these mountains are made up of beds of Ter- 
 tiary Age, though there are outcrops of Mesozoic beds in the depths of the 
 deeper gulches. 
 
 This range marks the continuation of the displacement that I have 
 called the great Uinta fault, and the evidences of the reverse movement are 
 complete. The first movement, which was upheaval on the Uinta side and 
 throw on the northeast side, seems to have been by monoclinal flexure, 
 while the last movement, which was throw on the Uinta side and upheaval 
 on the northeast side, was in part by flexure and in part by fracture. But 
 in the period of time separating the two movements the Brown's Park beds 
 were deposited across the zone of original flexure which had been greatly 
 degraded; still farther to the north west there is another line of displacement 
 approximately parallel to the first, with its throw also on the southwest side, 
 corresponding in this respect with the throw of the last displacement in the 
 Dry Mountain district. This northeast displacement fades out in a northwest 
 direction, and entirely disappears at the divide between the water-shed of 
 the Vermilion and the water-shed of the Snake River. When it is first seen 
 near this divide it is a gentle monoclinal flexure, and steadily increases in 
 abruptness along its line in a northeasterly direction until the bluffs of the 
 Snake River are reached, where it is seen as a dragged fault. There seems 
 to be no doubt that these displacements having throws to the southwest were 
 synchronous, while the evidence that the monoclinal flexure with throw to 
 the northeast was of earlier date is complete, for between the two periods 
 the Brown's Park beds were deposited that is, the Brown's Park beds are 
 seen to have been involved in the displacement having a southwest throw, 
 but took no part in the displacement with a northeast throw, as this last dis- 
 placement was made and the beds involved in it were truncated prior to the 
 deposition of the Brown's Park beds, and these beds were placed over their 
 upturned edges. 
 
 In the Dry Mountains some interesting facts have been observed. 
 Along or near to the line of double or reverse displacements we sometimes 
 find an escarpment facing the southwest, composed of beds of the Bridger 
 period, or of still lower Cenozoic rocks, and dipping back toward the north- 
 
208 STRUCTURAL GEOLOGY. 
 
 east, but as often we find escarpments facing the northeast composed of 
 beds of the Brown's Park period, horizontal or gently dipping to the south- 
 west, i. e., the escarpments of this range are sometimes reversed, because of 
 the reverse movement along the planes of fracture or the zone of flexure. 
 
 BROWN'S PARK. 
 
 In this discussion I shall not only include Brown's Park proper, but a 
 district of country stretching to the southwest, between the Dry Mountains 
 and Escalante Peaks to the Snake River. Here we have a geological basin 
 with a floor of Uinta Sandstone and Carboniferous and Mesozoic rocks. Its 
 longest diameter is in the same direction as the axis of the Uinta uplift, and 
 while the basin extends somewhat southward across the axis, yet the larger 
 part of the basin is on the north side of the axis. But the old lake basin 
 extended eastward and northward far beyond the area included in the Uinta 
 uplift and beyond the present channel of the Snake River, and here the floor 
 is unknown ; but this latter region is not within the limits of present discussion. 
 
 Within the region under discussion on the floor of the old lake basin 
 beds of the Brown's Park period were deposited; these beds lie chiefly in a 
 horizontal position, but on the north side of Brown's Park the beds are 
 abruptly turned up against the Uinta Sandstone of the O-wi-yu-kuts Plateau, 
 with a dip of about twenty-five degrees. Farther to the east, near the divide 
 between the waters of the Green and the Snake, south of the monoclinal 
 flexure and fault of the Dry Mountains, a deep synclinal flexure is observed; 
 parallel with it and still farther south another of less magnitude, and still 
 beyond a third but slightly developed. 
 
 Let us now consider the effect which the reverse throw along the great 
 Uinta fault and the throw along the Yampa fault has had on this valley. 
 In the former the downthrow at Red Creek is perhaps less than 1,000 feet; 
 at Diamond Peak, about 3,000 feet; and the total throw of the two displace- 
 ments in the Dry Mountains and vicinity is probably more than 4,000 feet. 
 The throw of the Yampa fault, from its inception on the west, soon attains 
 a magnitude of 5,000 feet, and where it is lost by transverse structure, near 
 Junction Mountain, it is about 3,000 feet. Thus it is seen that the great 
 block between these two faults lias fallen down from 1,000 to 5,000 feet in 
 
BROWN'S PARK ASPEN MOUNTAIN DISTRICT. 209 
 
 its different portions. Prior to this downthrow there was a great elevated 
 valley drained into the Green River. When the downthrow commenced it 
 is probable that the Brown's Park beds were not yet deposited, but after it 
 had continued for some time the region was so depressed that the waters of 
 the stream were ponded and a lake formed. In this lake, then, the Brown's 
 Park beds were accumulated. 
 
 We know that the Brown's Park beds were involved in a part at least 
 of this downthrow, and hence were deposited before the downthrow was 
 accomplished, because the beds themselves were involved in the displace- 
 ment; they are severed by faults and bent by fractures where they are seen 
 to overlap or extend beyond the area of downthrow. 
 
 Hence it is seen that Brown's Park is not a valley of displacement 
 o'r of subsidence, but was originally formed as a valley of degradation an 
 elevated valley in a mountain region. It subsided or fell down as a part of 
 a greater block. But the whole of it did not thus subside, for the Dry Mount- 
 ain's stand across the site of this ancient depression. 
 
 ASPEN MOUNTAIN DISTRICT. 
 
 In this district we have a great upheaval with its axis in a north and 
 south -direction, at right angles to the Uinta upheaval. On either side of 
 the upheaval there are zones of maximum flexure. 
 
 The beds brought to view in the degradation of this upheaval are all 
 the Cretaceous formations above the Henry's Fork Group and all the Cenozoic 
 groups below the Brown's Park; hence the inception of this upheaval dates 
 from some epoch in Post-Bridger time. The whole of the uplift is not within 
 the area embraced in the map. The section, together with the geological 
 map, presents all the important characteristics of this uplift, but there are 
 some minor features of interest. In the northwest, northeast, and southeast 
 angles or corners of the uplift there are many minor faults normal to the 
 strike of the beds. Quien Hornet Mountain stands on the southwest corner. 
 No faults have been discovered here. 
 
 There is. a gentle synclinal between the end of the Aspen Mountain 
 uplift and the side of the Uinta uplift. At the south end of the uplift the 
 
 axis passes through the eastern end of Aspen Mountain. Farther north- 
 14 P o 
 
210 STRUCTURAL GEOLOGY. 
 
 ward the axial region, topographically, is a valley, for Bitter Creek divides 
 the uplift, a stream having an extra limital source a stream whose course 
 was determined antecedent to the uplift. 
 
 In the heart of the uplift Cretaceous beds of extreme friability are found, 
 and the secondary drainage or lateral wet-weather tributaries to Bitter Creek 
 have excavated these valleys to the very heart of the uplift. 
 
 Here 10,000 feet of beds have been carried away by the waters since 
 the inception of the uplift. 
 
INDEX. 
 
 Pago. 
 
 Amplexus zaphrentiformis 107 
 
 Anchura prolabiata . 121 
 
 ruida 120 
 
 Anticlinal Structure v 10,17,24 
 
 Appalachian Mountains ." 24 
 
 Structure 9,24 
 
 Area Coalvillensis 115 
 
 Archajocidaris cratis 109 
 
 Avicula Parkeusis 115 
 
 Aspen Mountain ' 160 
 
 district 153 
 
 , Structure of 209 
 
 Bannister, Dr. H. M 48 
 
 Basin Province 6, 7, 29 
 
 , Orograpbic structure of ". 23 
 
 , Summary of history of. 32 
 
 Ranges 6,24 
 
 , Sedimentary rocks of 8 
 
 Range Structure 16,17,19,24,29 
 
 Bellerophon carbonarius Cox, var. snbpapillosus 92 
 
 Bishop Mountain Conglomerate, Distribution of 169 
 
 relations 62,165,170,199 
 
 type localities 44 
 
 Bitter Creek Group, Distribution of , 162 
 
 Delations 64,162 
 
 , type localities 45 
 
 Black Butte 160 
 
 Quartzito 160 
 
 Blake, Prof. VV. P., on the Plateau Province 3 
 
 Bridger Group, Distribution of 167 
 
 , Fossils of 105 
 
 , relations 63,167,199 
 
 , type localities 45 
 
 Brown's Park Group, Distribution of 168 
 
 , relations 63,199,208 
 
 , Structure of 208 
 
 Group, type localities 44 
 
 Bruce Mountain 163 
 
 Butte, Black * 160 
 
 , Pilot 18,25 
 
 Buttes 15 
 
 Cameo mountains 15 
 
 Cameo Mountains 15 
 
 Structure 15 
 
 211 
 
212 INDEX. 
 
 Page. 
 
 Camptonectes platessiformis 93 
 
 Canon of Desolation, Later views on fossils from IX 
 
 Carboniferous Period, fossils of 88 
 
 Catalogue of fossils 88 
 
 Cliffs of Displacement 14 
 
 Erosion : 15 
 
 Colorado River 193 
 
 Conformity of the Cretaceous 15(5 
 
 Cope, Prof. E. D., on separation of Tertiary and Cretaceous 72 
 
 Washiki Group G5, 156 
 
 Corbicula Powelli 127 
 
 Corbnla snbtmdifera 129 
 
 Corrasion 189 
 
 Correlation of Cretaceous and Tertiary Groups 71 
 
 Cretaceous Period, fossils of 94, 101 
 
 Cyrena (Veloritina) erecta 117 
 
 Declivity as a condition of degradation 184,186,187,189,192,195,197 
 
 Descriptions of new species of fossils 107 
 
 Degradation 182 
 
 , Methods of 188 
 
 of the Uiuta Mountains 181 
 
 Desolation, Canon of, Later views on fossils from; T IX 
 
 Diamond Peak 164 
 
 Structure of 204 
 
 Disintegration : 182 
 
 Dynamics of 183 
 
 Displacement, Cliffs of 14 
 
 diagrams 174 
 
 , Diverse 16,17,25,29,31 
 
 , Slopes of 14 
 
 ', Types of 17 
 
 of the Uinta Mountains 176 
 
 , Zones of diverse 16, 17 
 
 Diverse displacement 16,17,25,29,31 
 
 Drainage, Antecedent and superimposed 12 
 
 , Reversed 35 
 
 of the three geological provinces 7 
 
 Drift 171 
 
 Dry Mountains, Structure of 206 
 
 Dnttou, Capt. C. E., on Black Butto Quartzite 160 
 
 Dutton, Capt. C. E., on reversed drainage 35 
 
 Ellsworth, Mount "20 
 
 Epochs separating groups 61 
 
 Erisocrinus typus 89 
 
 Erosion 188 
 
 as a measure of geological time 33 
 
 , Conditions affecting rapidity of 34 
 
 Eruptive mountains 36 
 
 , Types of 18,22 
 
 Eupachycriuus platybasis 108 
 
 Flaming Gorge district 140 
 
 Group, Distribution of 151 
 
 , Fossils of ,. 92 
 
 , relations 68 
 
 , Section of ; 152 
 
INDEX. 213 
 
 Page. 
 
 Flaming Gorge Group, typo localities 51 
 
 Flexure, Maximum jg 
 
 Flotation Ig^ 
 
 Fossils, Catalogue of gy 
 
 , Cretaceous, from beyond the limits of the Plateau Province 101 
 
 , Descriptions of new species of . ... . 107 
 
 of the Bitter Creek Group 102 
 
 Bridger Group 105 
 
 Brown's Park Group 106 
 
 Carboniferous Period 38 
 
 Cretaceous Period 94 
 
 Flaming Gorge Group 93 
 
 Henry's Fork Group 94 
 
 Jurassic Period 93 
 
 Lower Aubrey Group gg 
 
 Lower Green Eiver Group 104 
 
 Point of Rocks Group 99 
 
 Red Wall Group gg 
 
 Salt Wells Group 97 
 
 Sulphur Creek Group 95 
 
 Tertiary Period , 102 
 
 Upper Green River Group 104 
 
 Upper Aubrey Group 91 
 
 , Tertiary, from beyond the limits of the Plateau Province 106 
 
 General observations on the collections 75 
 
 of Carboniferous Age 79 
 
 Cenozoic Age 84 
 
 Cretaceous Period 81 
 
 Devonian Age 79 
 
 Jurassic Period 81 
 
 Lower Silurian Age 79 
 
 Mesozoic Age 80 
 
 Tertiary Period 84 
 
 Triassic Period 80 
 
 Upper Silurian Age 79 
 
 Geology of the Uiuta Mountains 13 J 
 
 Gilbert, Mr. G. K., on age of Touto Group 56 
 
 displacements 180 
 
 diverse displacements 16 
 
 Henry Mountains 20 
 
 structure of Basin Ranges 23 
 
 Goniobasis Cleburni 122 
 
 Grand Canon Group, relations 70 
 
 , type localities '. 61 
 
 Schists 62 
 
 llayden, Dr. F. V 65,67 
 
 Helix Kauabeusis 120 
 
 peripheria 130 
 
 riparia 130 
 
 Henry Mountain Structure 20 
 
 Henry's Fork Group, Distribution of 153 
 
 , Fossils of 94 
 
 , relations , 68 
 
 , Section of 68, 157 
 
 , type localities 50 
 
214 INDEX. 
 
 Pago. 
 
 Ho\vell, Mr. Edvviu E., 011 reversed drainage 35 
 
 Hydrobia recta 132 
 
 Utahensis 132 
 
 Illustrations described ... 173 
 
 Island Park district 147 
 
 Inocerarnns Gilbert! 113 
 
 Howelli 114 
 
 Junction Mountain 10,11,145,204 
 
 Jurassic Period, Fossils of 92 
 
 Kaibab Structure 14,17,28,29,30 
 
 King, Mr. Clarence, on Basin Ranges 25 
 
 Leidy, Prof.J - 72 
 
 Leidy'sPeak 176 
 
 Leioplax ? tnrricula , 133 
 
 Lesquereux, Prof. Leo, on subdivision of the Tertiary 72 
 
 Localities for study of sedimentary groups 44 
 
 Lodoro Group 56 
 
 , Distribution of 147 
 
 , relations 144 
 
 , Section of 57 
 
 Lower Aubrey Group, Distribution of 148 
 
 , Section of - 57 
 
 , type localities 3 
 
 Lower Green River Group, Distribution of 166 
 
 , Fossils of 104 
 
 , relations 63,166,199 
 
 , type localities 45 
 
 Lunatia Utahensis 122 
 
 Marine Tertiary fossils 36 
 
 Marsh, Prof. O. C., on geology of Uinta Mountains 14 1 
 
 separation of Tertiary and Cretaceous 72 
 
 Marvine, Archibald If. VIII 
 
 on Park Mountains - 27 
 
 Meek and Hayden, Messrs., on subdivisions of the Cretaceous 67 
 
 Meek, Frof. F. B 32,48,50 
 
 on section at Sulphur Creek 158 
 
 separation of Tertiary and Cretaceous 72 
 
 Melauia Larnnda - 131 
 
 Mesodesma Bishopi 128 
 
 MonocliuaL Ridges - 11,13,14,16 
 
 Moraiual deposits 171 
 
 Mountain, Aspen 160, 209 
 
 , Bruce 163 
 
 , Junction 10,11,145,204 
 
 Mountains, Appalachian 24 
 
 composed of extravasated material 18 
 
 sedimentary strata - 9, 21 
 
 Dry, Structure of 206 
 
 ephemeral 196 
 
 , Henry 20 
 
 ,Park . 26 
 
 , Rocky, defined 5 
 
 ,Tushar " 19 
 
 , Uiukaret .. 18,26 
 
 3 Uiuta 11,25,136,173 
 
INDEX. 215 
 
 Page. 
 
 Mountains, Wasatch 30 31 
 
 Mount Ellsworth , 4i . 20 
 
 Naticopsis rcmox . ^ 10<J 
 
 Neritina ? ? Powelli <. 110 
 
 vol vilineata * , ,-. , 131 
 
 No w berry, Dr. J. S., on the Plateau Province 3 
 
 Nomenclature of formations . 38 
 
 Odontobasis buccinoidea 124 
 
 Ostrea (Alectryouia) procumbens . 93 
 
 sanniouis 112 
 
 Paleontology . . 4 ?4 
 
 Park, Brown's, Structure of 4 t 208 
 
 Mountains >. .. 26 
 
 defined ^ , . . ,. . 5 
 
 Province ..* . . 30 
 
 ,Orographic structure of 25 
 
 Parks, The 26 
 
 Peaks, Axial . 4 , 13 
 
 , Flanking _ t 13 
 
 Petrology as related to disintegration . .;. ..;_.... 182 
 
 Phorua exoneratus ...*..... 134 
 
 Pbysa Kauabeusis , 119 
 
 Pilot Butte, Wyoming , .**....* 18,25 
 
 Pisidiuiu saginatuui ..*...... 128 
 
 Plauorbis (Bathyomphalus) Kanabensis 119 
 
 Plateau Province ....... ^9 
 
 defined . t 3 
 
 , Dr. J. S. Nswberry on 3 
 
 , Fossils of 74 
 
 , Orographic structure of 25 
 
 , Prof. W. P. Blake on 3 
 
 , Sedimentary groups of... 37 
 
 , Summary of history of 32 
 
 Plateaus, Inclined 11 
 
 , Subsidiary 12 
 
 Plateau, Yampa, Structure of 202 
 
 PlatteKiver '. 194 
 
 Plicatula hydrotheca 113 
 
 Po Canon district 146 
 
 Point of Rocks Group, Fossils of 99 
 
 , relations 6, 155, 164 
 
 , Section of 15(i, 158 
 
 , type localities 47 
 
 Province, Basin 23,29,67 
 
 , Park 7,26,30 
 
 , Plateau 25,29 
 
 defined 3 
 
 Provinces, Geological, Characteristics of 7 
 
 , defined 3,7 
 
 , Groups of sedimentary rocks of 8 
 
 , separation indefinite 30 
 
 , Summary of history of 32 
 
 , Tj pes of orographic structure of 9 
 
 Pupa arenula 131 
 
 Pupa iucolata 130 
 
216 INDEX. 
 
 Page. 
 
 Rain-full and erosion 188 
 
 Red Creek Group, Distribution of 137 
 
 , relations 70 
 
 , type localities 62 
 
 Wall Group, Distribution of 47 
 
 , Sections of 57 
 
 , type localities >"> 
 
 Rb.ytopb.orus Meekii 118 
 
 Richard's Peak 1G3 
 
 Ridges, Monoclinal 11, 13, 14, 16 
 
 , Projecting ..-. 13,15 
 
 River, Colorado 193 
 
 , Platte 194 
 
 , Virgin lltt 
 
 , Yampa 11 
 
 Rocky Mountains defined 5 
 
 Rogers, Messrs 9, 24 
 
 Routes of travel VI 
 
 Salt Wells Group, Distribution of 154 
 
 , Fossils of 1)7 
 
 , relations 6G 
 
 , Sections of 1 57 , 159 
 
 , type localities 49 
 
 Sun Francisco Mountain 26 
 
 Sapping 191 
 
 Sectious, Structure IT:'. 
 
 Sedimentary groups, Distribution of, in tbe tbree geological provinces 
 
 of tbe Plateau Province 37 
 
 , Table of 40 
 
 Sedimentation 193 
 
 Sbiuarump Group, Distribution of 150 
 
 , ivlutions 68 
 
 , Sectious of 53. 112 
 
 , type localities 54 
 
 Sbore-liue of Mesozoie and Tertiary seas 
 
 Stereograin 175 
 
 Steward, Mr. John F 57.142 
 
 Structural geology of the I" hit a Mountains 176 
 
 Structure, Anticlinal 10. 17. -24 
 
 , Appalachian 9, 24 
 
 , Basin Range 16,17. - . 
 
 . Cameo * 15 
 
 , Henry Mountain 
 
 , Kuiliab 14,17.2 
 
 , Orographie, of the Basin Province 23 
 
 Park Province 
 
 Plateau Province 
 
 , Summary of orographie 
 
 .sections 173 
 
 Structures, Orographie 9. 21 
 
 Structure, Table Mountain 1- 
 
 , Tushar 19,25.26 
 
 , Uinkaret 1? 
 
 , Uinta 11. 17 - 26 
 
 , Volcanic . . 1.' 
 
ISTDEX- 
 
 217 
 
218 INDEX. 
 
 Page. 
 
 Wusatch Mountains t 31 
 
 White Cliff Group, Distribution of 151 
 
 , relations 18 
 
 , Sections of 53, 152 
 
 , type locality 51 
 
 White, Dr. C. A., report on invertebrate paleontology of the Plateau Province 74 
 
 Tampa district 14G 
 
 Eiver , 11 
 
 Plateau, Structure of 202 
 

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