UNITED STATES DEPARTMENT OF THE INTERIOR 

J. A. Krug, SecPetary 

GEOLOGICAL SURVEY 

.W. E. Wrather, Director 

Professional Paper 205-D 

LATE MESOZOIC AND EARLY CENOZOIC HISTORY 

OF CENTRAL UTAH 

BY 

EDMUND M. SPIEKER 

. Shorter contributions· to general geology, 1943-45 

(Pages 117-161) 

UNITED STATES 

GOVERNMENT PRINTING OFFICE 

WASHINGTON: 1946 

For sale by the Superintendent of Documents, U. S. Government Printing Office, W asbingtoq 25, D . C. 

Price 15 cents ' 
NOTE.-This repo~·t was finished by the author in 1940, and 

it takes no account of other reports published since that time. 

The stress of current conditions does not permit the additions 

and revision necessary to bring it up to date. Rather than 

delay the publication of the available material indefinitely, the 

paper is offered as it is. 
. CONTENTS 

Abstract-------------- ------------- -- -------- --- Introduction __________ ~--------------- --- ------- --- Background of present revision ___________ .. __________ _ General setting ______ ______ ____________________ _ 

Outline of investigation and summary of conclusion __ Revised stratigraphic section ____ _____ ______________ .. _ General features ________ ________________ _______ _ Jurassic system _____ _____________________ ______ _ 

Regional nomenclature __ ___________________ _ Arapien shale ________ ____ . ________________ _ 

Definition, distribution, and general stratigraphic relations __ ______ _____________ _ 

Lithologic character, subdivision, and thickness-----------·---- ------------~---- Age and correlation __ _______________ ___ _ Morrison ('?) formation ________ -________ __ ___ _ Cretaceous system ____ _______________ __________ _ 

General character and distribution ___________ _ Indianola group ____ ________ _______________ _ 

Definition and nomenclature ___ ___ ______ _ Sanpete formation _____________________ _ Allen Valley shale ____ _____ _______ ______ _ 

Funk Valley formation _________ ____ ____ _ Sixmile Canyon formation ______________ _ 

Indianola group (undifferentiated) ____ ___ _ Rocks of early and middle Montana age ___ ___ _ Price River formation ______________________ _ 

Definition and lithologic character ______ _ _ Distribution and stratigraphic relations __ _ _ Age ________________ - - - - - - - - - - - - - .. - - - - -

Regional relations and correlation west- 'vard __________ _____________________ _ 

Representative sections _____________ ____ _ Fossils ________________________________ _ 

Cretaceous and Tertiary systems ____________ ____ _ North Horn formation _____________ _________ _ 

Definition and lithologic character __ ___ __ _ Regional characteristics _________________ _ Relation to adjacent formations _____ ____ _ Age and -correlation ____ __ ___ _______ ____ _ Use of term Paleocene ________________ __ ___ _ _ 

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Revised stratigraphic section-Continued 

Tertiary system __ __________ _______________ . ____ _ Flagstaff limestone ______ ____ _ ~ ____ . ______ __ _ 

Definition, lithologic character, ann extent __ Regional relations __ ________________ . ___ _ Age and correlation __ _____ ___ ___________ _ 

Pre-Flagstaff unconformity _______ :. ______ _ VVasatch problem ____ _____________ ______ ___ _ 

Colton formation _____ __________ ___________ _ 

Definition, general character, and relation- ships __________ _______ _____________ _ 

Distribution ___________________________ _ Age and correlation ___ _________________ _ 

Green River formation ____ _______ __ ________ _ 

Reconnaissance east of VV asatch Plateau_.:: _________ _ VV est Tavaputs Plateau ____ ___________ ______ _ Green River Canyon _______________________ _ 

Cretaceous-Tertiary boundary problem __ ______ ______ . _ General considerations _____ _____________________ _ 

. • Question of basis for time division _____ ______ ____ _ The orogenic record__ _ _ __________ __ __ ___ '" _ _ _ _ _ The epeirogenic record _________________________ _ 

The paleontologic record ________________________ _ 

Nature and extent of orogenic movements __ __________ _ Nomenclature ____ ____ ____ .. _____________________ _ 

Scope of discussion_______ ___________ _ ________ _ 

Mid-Cretaceous orogeny ________________________ _ 

Early Laramide orogeny _______________________ _ _ 

Pre-Flagstaff movement ___________ . _ _ _ _ _ _ _ _ _ _ _ ' 

Paleogeography and geologic history _________________ _ 

Diagrammatic reconstructions ____ ______ _________ _ 

Upper Jurassic and Lower Cretaceous ____________ _ 

Early Upper c;etaceous (Colorado) _______ ______ _ The geosyncline ________________ .. ______________ _ 

Early to Middle Montana ______________________ _ 

Late Montana and Lance __ __ ____ ____ . __________ _ 

Paleocene (Fort Union) _________________________ _ 

Eocene (VV asatch and Green River) ______________ _ Index ___ ________ ___ _____ __________________________ _ 

. ILLUSTRATIONS 

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PLATE 18. Arapien shale: A, At the type locality in Arapien Valley; B, In the Salina district______ _____________________ 138 

19. Indianola group: A, Undifferentiated Indianola in the Gunnison Plateau; B, Funk Valley formation __ -------- 138 

20. A, B, Sandstones of the Price River formation near Castlegate____ ___ ________ _______ _____________ _______ __ 138 

21. Conglomerates of the Price River formation, western facies: A, Conglomerate in Red Narrows, east of Thistle; 

B, Price River and Indianola strata on Hjork Creek_______ ______________ ___ ___________________________ 138 

22. A, Flagstaff limestone on crest of Wasatch Plateau; B, North Horn formation at type locality________________ 138 

23. A, Colton and North Horn formations in Green River Canyon; B, Green River strata on Minnie Maud Creek__ 138 

24. Unconformities beneath Price River· and North Horn formations: A, North Horn formation in east front of 

Wasatch Mountains at Thistle; B, Price River-Indianola contact near Wales __________ '- ______ ':_ ____ _______ 138 

25. Unconformity beneath Flagstaff limestone: A, Flagstaff-North Horn unconformity in Sixmile district; B, Angular 

unconformity between Flagstaff limestone and Indianola group in Salina Canyon_______________________ ___ 138 

FIGURE 14. Index map of part of Utah showing the localities discussed in this report______________________________ ___ __ 119 

15. Relationships of stratigraphic units across the Wasatch Plateau, showing equivalence with units described in earlierreports _______________________________________________________________ _:________ ___ _________ 122 

16. Cross sections showing relations of Arapien, Indianola, and Price River strata in northern VVasatch Plateau and 

central-eastern Gunnison Plateau___________________________________________________________________ 129 

17. Cross section of rocks exposed in Six mile Canyon near MantL _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 133 

18. Stratigraphic diagram, northern Wasatch Plateau to Green River_________________ ____ ____________________ 141 

19. Age determinations of Laramide orogeny in Europe_____________________________________________________ 144 

20. Map of western part of United States showing probable eastern margin of mid-Cretaceous folding___________ __ 151 

21. Block diagrams showing Utah north of latitude 39°30' at four stages in late Cretaceous time_________ ________ 157 

Ill 
) 

I 
LATE MESOZOIC AND EARLY CENOZOIC HISTORY. OF 

CENTRAL UTAH . 

By EDMUND M. SPIEKER 

ABSTRACT 

The discovery of dinosaur bones in strata of central Utah 

fot·merly assigned to the Wasatch formation, together with other 

findings, notably the recognition of a very thick section o~ con- glomerates as Colorado in age, bas made poSsible an outlme of 

late Mesozoic and early Cenozoic history considerably different 

from the scheme hitherto conceived. Important changes are the 

recognition of an orogenic epoch in the eastern part of the Great 

Basin early in Upper Cretaceous time and the placing of the 

main Laramide folding of central Utah between middle and 

late Montana time instead of at the end of the Cretaceous, as .heretofore thought. This paper presents the data bearing on these conclusions, together with many other stratigraphic and 

structural determinations that bear on the history and paleogeography of the region, and offers discussion of certain problems that are involved. 

The stratigraphic section considered in this report begins with 

the Ara:pien shale, Upper Jurassic in age, a unit perhaps 10,000 

feet thick of marine shale with beds of fine-grained sandstone, 

salt, and gypsum. Strata that possibly belong to. the Morrison 

formation come next, and above them is a group of clastic I<ocks, 

ranging from boulder fan conglomerate to marine shale and 

including a wide variety of sedimentary types, 8,000 to 15,000 

feet thick, named the Indianola group and subdivided where 

possible into four formations, as follows: The Sanpete at the 

base, sandstone and conglomerate, is of early Colorado age; the 

Allen Valley, marine shale, middle Colorado; the Funk Valley 

formation, sandstone and marine shale, late Colorado; and the 

Sixmile Canyon formation, conglomerate and sandstone w..ith a finer-textured coal-bearing member, late Colorado. These strata 

grade eastward to the marine Mancos shale of Castle Valley 

and the Book Cliffs ; westward they change rapiP,ly to coarse conglomerates, red beds, and fresh-water limestones, with local 

marine beds, which accumulated in a rapidly subsiding piedmont belt. ·strata of early and middle Montana age are similar 

to those of the eastern Wasatch Plateau and are not described. 

The Indianola and older rocks are truncated by an angular 

unconformity, which was developed after the main Laramide 

folding. Above this unconformity is a conglomerate of late 

Montana age formerly classified as the basal Wasatch conglomerate but now correlated with the Price River formation of cen- tral and eastern Utah. Next above are the variegated mudstones and sandstones with local fresh-water limestone formerly 

included in the lower member of the Wasatch formation, now set apart as the North Horn formation. The lower part of this 

formation contains a dinosaurian fauna of probable Lance age, 

and the upper part contains mammalian faunas of Paleocene 

age; the Cretaceous-Tertiary boundary lies within the formation, unrecognizable by known physical criteria. Above the 

North Horn is the Flagstaff limestone, lacustrine in origin, formerly classified as the middle member of the Wasatch formation, possibly Fort Union (Paleocene) in age. On the west 

flank of the Wasatch Plateau the Flagstaff overlies all older 

beds in angular unconformity developed on a local fold. Elsewhere the basal Flagstaff is transitional with the North Horn. 

Above the Flagstaff is a unit of red beds and gray sandstone, formerly considered to be the upper member of the Wasatch 

formation, now classified as the Colton formation, in the ab- sence of definite evidence respecting its age. These beds are overlain by the Green River formation, with which they intertongue, disappearing westward so that in the northwestern part 

of the Wasatch Plateau there are no beds of Wasatch type; but 

the Flagstaff passes upward into the Green River formation with 

only slight change. East of the Wasatch Plateau the basal Green 

River and Colton intertongue further, and the Flagstaff thins 

to insignificance; on Green River at the mouth of Desolation 

Canyon the Flagstaff is doubtfully recognizable, and the upper 

1,000 feet, approximately, of Colton strata is equivalent to basal 

Green River of the northeastern part of the Wasatch Plateau. 

The Cretaceous-Tertiary boundary problem is affected by the new findings to the extent that the evidence of strong orogenic 

movement in the central Utah di-str-icts of the Cordillera is now found to be so far below the upper limits of characteristic 

Cretaceous strata that it can hardly be a factor in determining 

the boundary. Various possible criteria for the subdivision are discussed ; orogenic movements are examined to determine possible values in correlation as prerequisite to consideration for 

subdivision, and it is concluded that the postulate of world-wide 

simultaneity is not demonstrated for the known late Mesozoic 

and early Cenozoic orogenic episodes. Clear differentiation 

between Cretaceous and Tertiary in most of the world is due to 

extensive epeirogenic movement and widespread withdrawal of 

the sea the culmination of which might seem possible as a criterio~ but the determination of an exact maximum is too 

difficult.' The record of fossils, deSpite the fact that fossils are not necessarily precise indicators of contemporaneity, still affords the best available means of correlation, and a subdivision 

based solely on diagnostic fossils seems best. Question arises as to how the fossi.l evidence should be used. In the present problem it is logical to put the boundary at the horizon at which the 

greatest change takes place in total faunas from characteristic 

Cretaceous to characteristic Tertiary. In applying this criterion, the paleontologic opinion seems to favor for the interior 

of North America the boundary between the Lance and the Fort 

Union. 

Three orogenic movements are recognized in the time span 

covered by this report, one at seme time between the Upper 

Jurassic and the Upper Cretaceous, probably early Colorado, 

here called the mid-Cretaceous moyement; one between middle 

and late Montana times, called the early Laramide movement; 

the third probably in Paleocene time, not certainly dated and 

referred to the local stratigraphic section as the pre-Flagstaff 

movement. The mid-Cretaceous movement is not definitely 

proved by angular unconformity, but is virtually demonstrated 

by the nature of the conglomerates in the Indianola group and 

is thought to have affected a belt not far west of the southern 

Wasatch Mountains. Evidence in southern Idaho, the central 

Wasatch Mountains and southern Nevada suggests that this 

movement may bav~ been widespread. Uncertainty regarding 

the age of the basal conglomerates of the Indianola group prevents accurate estimate of date, but available evidence suggests 

early Upper Cretaceous or lnte Lower Cretaceous age. The sec- ond movement, the early Laramide, is accurately placed between 

the Blackhawk and Price River formations. Evidence of Lara- ·mide movement so early is generally lacking in the Cordilleran 

region, but nothing is known to controvert it, and in southwestern 

Montana there is suggestive evidence that the Laramide orogeny 

began at the time the Judith River formation was deposited. 

Districts east of the northern Rocky Mountain-Wasatch: Mountain lineament, such as the Uinta Mountains and the Colorado 

Rockies, were probably- folded later. The third movement, the 

pre-Flagstaff, was localized in central Utah in the SanpeteSevier Valley belt. Data on the age of the upper parts of the 

Norti::i Horn and Flagstaff formations suggest Fort Union age. 

Correlation with other regions is uncertain, but the character of 

the central Utah structure and the regional stratigraphy suggest 

that the movement was contemporaneous with the formation of 

the monoclines in the Colorado Plateau province, interpreted as the result of deep-seated thrusting. . The facts now available permit paleogeographic reconstruction of central and eastern Utah between the beginning of the 

Upper Cretaceous and the end of the Cretaceous. Four block 

diagrams show successive stages in the development of the pred- ecessors of the Wasatch Mountains from late Mesozoic geosyncline. They also show areas toward the east in which the 

117 
118 ' SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1.943-45 

~ediments of the existing rock section were deposited. In early 

Upper Cretaceous time the mountain belt was west of the present 

southern 'Vasatch Mountains and extended slightly east of 

north toward southeastern Idaho. 'l'he piedmont area was a rapidly subsiding trough in which coarse boulder and gravel 

fans spread out, and into which the sea spread at times; to the 

east lay locally swampy, sandy coastal plains and the open sea. Through Colorado time sedimentation was very active in the 

piedmont belt, 10,000 to 15,000 feet of strata, dominantly coarse, 

accumulating in the already pronounced geosyncline and bringing the total known thickness of pre-Montana rocks to more than 40,000 feet. This stage of the geosynclinal development is seen to be part of a series, beginning with the Cambrian, of 

epochs of profound subsidence, which shifted eastward and fol- · ·lowed one another at progressively shorter intervals. In early 

and middle Montana time finer sediments were deposited, and 

the extensive coal beds of the Wasatch Plateau were formed; 

the sea retreated eastward as sediments were spread out into 

the marine basin, and epochs of accelerated subsidence caused 

successive reinvasions and intertonguing of the resulting sediments. Before late Montana time the early Laramide orogenic 

episode occurred, and the sediments of the geosyncline were folded as far east as the western border of the Wasatch Plateau. 

Debris from the mountains was spread widely eastward, part 

of it forming across eastern Utah an extensive sandstone tongue, 

the Castlegate member of the Price River formation. The sea reinvaded, burying these sands under muds, and then retreated as before, the shore zone reaching the eastern limits of Utah 

in late Montana time. In latest Cretaceous time flood plains 

and lakes overspread the region, and a variety of sediments 

accumulated; this sedimentation continued into Paleocene time 

without interruption or change. Probably in the middle Pale- ocene (Fort Union) another disturbance occurred, producing in 

the Sanpete Valley district a single fold, which was rapidly 

truncated and overlapped by the extensive Flagstaff Lake, in 

which limestone accumulated. Probably in Colton time floodplain sediments invaded from the east, and thereafter the lake 

spread eastward, depositing muds and calcareous deposits of the 

Green · River formation over the whole of central and eastern 

Utah. 

INTRODUCTION 

In central Utah the late Mesozoic and early Cenozoic 

!Lges are recorded in a rock section of unusual interest. 

Until 1935 the region appeared to be entirely lacking 

in physical record of the time between the late Montana 

epoch of the Upper Cretaceous and the Wasatch epoch 

of the Eocene, but the discovery of dinosaurian remains 

in strata formerly classified as Wasatch has resulted in 

the abrupt shifting of a considerable section of rocks and 

a pronounced angular unconformity from a'Position in 

the stratigraphic column apparently well above the base 

of the Tertiary to one clearly within the limits of the 

Cretaceous. The closing stages of the Mesozoic are now 

seen to be well represented, instead of completely un- recorde~. The main Laramide movement in this region 

is thus revealed to have taken place long before the end 

of the Cretaceous, instead of marking the end of the 

period as it has hitherto been thought to do. Further, 

tll.e discovery of marine beds, Colorado in age, in another thick formation formerly classified as Tertiary 

has produced another major shift in stratigraphic alinenient, which brings to light evidence of an orogeny 

older than the Laramide and also accentuates the magnitude of the Mesozoic geosynclh1e in the region. 

Finally, the determination that the youngest rocks exposed in the early Laramide folding of the area are of 

Colorado age, instead of Montana, as earlier thought, 

has ·led to other changes in correlation, which make 

possible a more precise dating of the main Laramide 

orogeny .. than was formerly thought feasible. In respect to certain elements of stratigraphic and orogenic 

· succession, the record of physical events for the late 

Mesozoic is possibly more complete irl central Utah than 

anywhere else in North America. 

These discoveries require revision of the stratigraph~c 

section, the paleogeography, and the general geologiC 

history of the area. . This report is intended to present 

the major facts and to discuss certain of the problems 

involved in the revision. 

The data concerned have accumulated during the 

geologic mappi~g o~ the Wasatch Pla~eau and; the reconnaissance examinatiOn of surroundmg territory. In 

these tasks the writer has profited by advice and assistance from many more people than can expediently be 

mentioned here. Grateful acknowledgement must be 

made, however, to Hugh D. Miser for frie~dly support 

in the administration of the work and to John B. 

Reeside, Jr., for extensive consultati~m an~ col~aborat~on 

in both field and office and for all IdentificatiOn of Illvertebrate fossils. 'l!he reptilian remains have ·been 

studied by C. W. Gilmore, of whose interest in the prob~ 

lem the writer is highly appreciative. Thanks are due 

also to G. G. Simpson and C. L. Gazin for OI?inio~s on 

mammalian renlains, and toR. vV. Brmvn for Identification of fossil plants. Among associates in field parties 

of the Geological Survey, those who have contributed 

most toward the. working out of the geology here described are M~. P. Billings, A. W. Quinn, D. T. Griggs, 

and S. L. Schoff; it is a pleasure to acknowledge their 

important· an~ whole-hearted cooperation. T~e ~riter 

is especially Indebted to Mr. Schoff for permissiO~ to 

quote from his unpublished notes on the Cedar H~lls. 

To other colleagues in the Survey, notably J. B. Reeside, 

Jr., Arthur A. Baker, J.D. Sears, W. W. Rubey, W. H. 

Bradley, and H. D. Miser, thanks are expressed for 

helpful criticism of this report in manuscript form. 

BACKGROUND OF PRESENT REVISION 

GENERAL SETTING 

The Wasatch Plateau, the northernmost of the High 

Plateaus of Utah, is a high, deeply dissected tableland 

covering about 2,300 square miles in central Utah. (See 

fio-. 14.) It forms part of the western highland rim 

of the drainage basin of the Colorado River, constituting not only the major divide between that basin and 

the interior drainage of the Great Basin to the west, but 

also the boundary between the rather distinct geologic 

provinces of those two regions. The eastern margin of 

the plateau is a sweeping stretch of barren sandstone 

cliffs, a southward continuation of the Book Cliffs, surmounted by higher tabular masses, in all of which the 

strata dip at low angles and are essentially parallel, in 

the· general habit of the Colorado Plateaus. On the 

western margin the strata plunge tpward Sanpete and 

Sevier Valleys in the great Wasatch monocline, at the 

base of which the structure is complex, and a variously 

deformed rock succession is broken by several angular 

unconformities; the geologic features here ar,e typical 

of the Great Basin, and their eastern limit follows in a 

general way the western border of the plateau. 

The rocks of the plateau have long been divided into 

two major groups: ( 1) a lower succession of sandstone 

and shale, buff to gray, prominent in the east front and 

in the Boo~ Cliffs, marine in the lower part and continental in the upper, richly coal-bearing in part, of Cretaceous age;: and (2) an overlying succession of notably 

different rocks in which varicolored sandstone and 

shale, conglomerate, and fresh-water limestone are 

prominent. In the past the beds of the upper group, 

which form most of the higher tabular masses in the 
I 

LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL UTAH 119 

9·1----

111° 110~ 

·I ! ____ w y 0 M I N G .;,. _______ _ 

0 

BASIN 

SAN RAFAEL 

SWELL 

zoMiles 

Duchesn~ 

----t40 

FIGURE 14.-Index map of part of Utah, showing the localities discussed in this report. 

1. Dry Creek and Hjork Creek. 5. Allen Valley. · 9. Twist Gulch. ' 

2. Little Clear Creek. 6. Sixmile Canyon. 10. Mouth of Desolation Canyon on Green River. 

3. Bennion Creek. 7. Twelvemile Canyon. 4. North Horn Mountain. 8. Arapien Valley. 

plateau, were believed to ~e Tertiary and were assigned 

to the Wasatch formation. On the western margin of 

the plateau and adjacent parts of Sevier and Sanpete 

Valleys, the complicated structure brings to exposure 

various rock units of both groups and also large areas 

of Jurassic shale; but highly varied rocks like those of ~he upper group predominate, and in many places their 

relations have been difficult to work out. In the western districts, in general, the younger upper strata were 

found to overlie the older in strong angular unconform-

' ty, whereas in the eastern districts the little-disturbed 

succession of strata seemed to show no evidence of corresponding break. The local Cretaceous-Tertiary bound~ 

ary problem was thus complicated by the puzzling ·concealment in the eastern section of a disconformitythat 

should, it seemed, represent not only the strong angular 

unconformity of the western,section, but also the rather 

Tong interval between late Montana and early Eocene 

(Wasatch) times. The~e and other questions have 

been satisfactorily resolved by -the recent work,_ as outlined in the following paragraphs. 
120 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

OUTLINE OF INVESTIGATION AND SUMMARY OF 

. CONCLUSION 

The discovery of dinosaur bones in the supposed 

lower vV asatch .marked the turning point from which 

proceeded the changes in concept of the stratigraphy 

and geologic history of central Utah mentioned above. 

This discovery was preceded and :followed, however, by 

a number of ·other discoveries, hitherto unpublished, 

which were l!lade during the writer's _study an~ shoul_d 

be set :forth In explanatiOn of the revised stratigraphrc 

section. The :following paragraphs summarize the significant discoveries. In order to preserve unity in this 

chronologie account, stratigraphic names are given as 

used at the time the studies were made, whether or not 

they have since been changed. 

In 1925 J. B. Reeside, Jr., and the writer published a 

preliminary account of the stratigraphy of the Wasatch 

Plateau,1 in which there was presented a type section 

of the late Cretaceous and early Tertiary beds for Price 

Canyon and vicinity. Further description of the section appeared in 1931.2 The major units in this section 

are as follows·: 

Late Cretaceous and early T ertiary tonnations of the l ¥asatch 

Plateau (Price Canyon section) 

Eocene : Feet 

Green River formation: Gray shale, sandstone, oil 

shale, limestone. 

'Vasatch formation: 

Upper member: Sandstone, red shale; irregularly 

bedded------------------------------------- 1,500 

Flagstaff member : Limestone, shale, sandstone ; regularly bedded____________________________ 600 

Lower member: . Sandstone, gray to variegated 

shale, limestone, conglomerate, thin coal beds ; irregularly to evenly bedded _________________ 2,200 

Cretaceous : Price River formation: 

Upper member : Coarse gray sandstone, shale ; 

irregularly bedded-------------------------- 600 

Castlegate member: Cliff-making gray sand- stone ____________________________________ 300-500 

Blackhawk formation : Medium to fine-grained buff 

sandstone, shale, coaL _________________________ - 900 

Total (D?-aximum) -------------------------- 6, 300 

In this section the Wasatch formation was identified 

almost entirely on the basis of lithologic character, 

stratigraphic position, and connection by tracing with 

the Wasatch strata as identified to the east. At the type 

locality, · in southwestern Wyoming and northeaste}.'n 

Utah, the Wasatch formation consists of variegated 

sandstone and shale, with some conglomerate, volcanic 

ash, and fresh-water limestone. 3 Strata of these wellknown lithologic types have been traced in a general 

way, locally in accurate detail, across southwestern Wy_-

oming into northwestern Colorado and along the Book 

Cliffs into central Utah.4 Fossil evidence was meager, 

and the actual basis for assignment to the Wasatch was 

rather weak-i.n fact, as now reviewed, it consisted 

largely of tradition. Since the days of Powell and Dutton these strata had been identified as Tertiary, and in 

the absence of proof to the contrary the classification 

had been accepted and handed on. The fact that in the 

disturbed districts the strata are unconformable on the 

folds produced in the so-called Laramide revolution 

and conceived to mark the end of the Cretaceous appeared to support the determination of Tertiary age. 

In 1926 the writer collected from the lower member 

of the Wasatch fresh-water mollusks that augmented 

collections already on record, 5

_ and were reported by 

Reeside to include several species not known elsewhere 

in beds later than Fort Union. Certain of these species 

were :found also in the Flagstaff limestone. In the same 

year the Flagstaff, which throughout mo~t of the area 

overlies the lower member of theW asatch In apparently 

transitional conformity, was :fo~nd_ to _ove~lie it and 

older rocks in angular unconformity In Sr~nnle Canyon, 

south o~ Manti. (See fig. 17.) ~t that time th~re w~s 

some doubt as to the interpretatiOn of the relatwn~ In 

Sixmile Canyon because of locally severe de:formatw~, 

but in 1929 and 1930 the Flagstaff was :fo~nd to overl~e 

in angular unconformity al~ o~der ~ocks_In the MantiSalina district. In 1932 a similar situatiOn was :found 

farther north and finally in 1934 evidence was found 

to prove that the exposures in Sjxmile Canyon show 

angular unconformity and not shearing or other :form 

of :faulting. This evidence suggested that the break 

between the lower member and the Flagstaff might have 

time significanQe, and that the lower member might not 

be Wasatch, but rather Fort Union, iJ?- age. Vertebrate 

fossils were needed to settle the questwn, but the search 

for bones went unrewarded. 

In 1931 it was discovered that in the Thistle district 

the basal conglomerate of theW asatch forma~ion, whi~h 

there overlies folded Cretaceous and Jurassic strata m 

angular unconformity, is equivalent to the upper P!lrt; 

at least, of the Price River formatiQn of ~he type sectwn: 

but correlation of the lower part was a difficult problem. 

Brackish-water fossils not far above the Castlegate sandstone member 6 showed that roughly the lower half oi 

the formation, at least, is Montana in age. The postorogenic conglomerates and sandstones could not be accepted as Montana in age, because the youngest ~olded 

rocks in the western belt were thought to belong In the 

late Montana· 7 but in Price Canyon no boundary could 

be found bet~een the part of the Price River known 

to be of Montana age and the uppe~ be?-s equiv~lent t_o 

the postorogenic conglome::ate. This dis~overy Intensified the difficulty of locating the break In the eastern 

section but on the other hand it revealed the basal conglomer~te of the Wasatch as mor~ ~xtens~ve than ha_d 

earlier been thought and brought It Into view as a mut 

of regional importance. 

In the same year it was found that the upper member 

of the Wasatch formation intertongues with Green 

River strata between Soldier Summit and Thistle so 

that in the Thistle district the Flagstaff bmestone may 

1 Spieker, E. M., and Reeside, J. B., Jr., Cretaceous ~~;nd Tertiary for

mations of the Wasatch ·Plateau, Utah: Geol. Soc. Amer1ca Bull., vo.L 36. 

pp. 435-454, 1925. 2 Spieker, E. :M:., 'l'he Wasatch Plateau coal field, Utah: U. S. Geol 

Survey Bull. 819, pp. 39-47, 1931. , a Hayden, F. V., U. S. Geol. Survey Terr., 3d Ann. Rept., p. 90, 1869 

idem, 2d ed., p. 191, 1873. Veatch, A. C:, Geography and geology of l

nortion of southwestern Wyoming: U. S. Geol. Survey Prof. Paper 56 

pp. 88-96, 1907. 4 Wegemann, C. H .. The Coalville coal field, Utah: U. S. Geol. Surve~ 

BulL 581, pp. 161-184, 1915. Schultz, A. R., The southern part of th( 

Rock Springs coal field: U. S. Geol. Survey Bull. 381, pp. 214-281, 1910 

Gale, H. S., Coal fields of no-rthwestern Colorado and northeastern Utah 

U. S. Geol. Survey Bull. 415, 1910. Richardson, G. B., Reconnaissanc( 

of the Book Cliffs coal field: U. S. Geol. Survey BulL 371, 1909. Clark 

F. R., Economic geology of the Castlegate, Wellington, and Sunnysid1 quadrangles: U. S. Geol. Survey Bull. 793, 1928. Sears, J. D., Geolog3 and oil and gas prospects of part of Moffatt County, Colo., and southerx 

Sweetwater County, Wyo. : U. S. Geol. Survey Bull. 751, pp. 269-319 

1924. Sears, J. D., and Bradley, W. H., Relations of the Wasatch an( 

Green River formations in northwestern Colorado and southern Wyo ming: U. S. Geol. Survey Prof. Paper 132, pp. 93-107. 192~. Fisher 

D J The Book Cliffs coal field in Emery and Grand Counties, Utah 

u· s'' Geol Survey Bull. 852, 1936. Erdmann, C. E., The Book Cliff! 

coal .field i~ Garfield and Mesa Counties, Colo.: U. S. Geol. Survey Bull 

851, 1934. 6 Spieker, E. M., and Reeside, J. B., Jr., op. cit., pp. 400-451. e Spieker, E. M., and Reeside, J. B., Jr., op. cit., p. 446. 

'Spieker, E. M., and Reeside, J. B., Jr., Upper Cretaceous shorP. lin1 

in Utah: Geol. Soc. America Bull., vol. 37, pp. 429-438, 1926., 
LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF I ENTRAL UTAH 121 

be regarded as basal Greeri River· (see fig. 18) ; this ture of the conglierates proves disturbance not far 

raised the question whether the Flagstaff should be clas- to the ·west. · -

sified as a tongue of the Green River. · In 1935 Reeside and the writer had collected fos~il · 

In 1932 a fonnation much like the 'Vasatch for:tilation plants in Sixmile anyon, south of Manti (see fig. 14), 

was discovered in· the Indianola district, south of This- from the youngest! folded strat~ under the basal con- ., tie. It underlies the basal conglomerate of the Wasatch glqmerate of the 1'Vasa;tch, earlier thought to be late 

in angular unconforn1ity and overlies the folded Juras- L\1optana in age, ~s stated above. These fossils were 

sic of the area in a deformed contact suspected· of being a assigned by R. vV. Brown to the so-called Dakota flora. 

lower angular unconformity. These relations sug- The plant-bearing }trat.a had been determined to overlie 

gested two stages of folding instead of the one earlier sandstone and shal of proved Niobrara age, and tore- . pictured. Subsequent field work revealed a considerable solve the question thus raised the · writer . reexamined _ extent of this new formation in the western border belt; the structure in t~e Sixmile area, and" collected more 

it had earlier beep regarded as Wasatch and had been fossil plants and atso mollusks. These fossils were rethe source of much difficulty in the Salina district be- ported by Brown apd Reeside, respectively, to be Colocause of its ~issimilarity there to Wasatch strata nearby rado in age. This lren1oved the ·only evidence extal).t in 

to the east, In structvrally separated outcrops. favor of post-Montana age for the _folding; A review 

The need for definite paleontologic evidence 011 the of the relations in ~he northern part of the area showed 

age of _the beds classified as W asatc!l, and of th~ new that the ~'W asatcht' conglomerate is equivalent ' to the 

·formatiOn as well, thus became increas~ngly important. P. rice River for:tna~ion; the break in the eastern se~tion In 1934 the writer examined the type Wasatch, did some lies at the base o the Castlegate sandstone Inember, 

regional tracing of the strata, and searched for further where Reeside and the writer had earlier postulated a 

fossil evidence. One locality in the Wasatch Plateau, hiatuS.10 · , -

o~ North Horn Mountain · (location 4 on fig. 14), In 1937 C. "\V. "lmore, G. W. ~ternberg, and G. B. 

yielded an assortment of bone s.craps that were identified Pearce, of the Sn1 thsonian Institution, spent about 5 

by C. W. Gilmore as mainly dinosaurian. This discov- _ weeks in the central part of the Wasatch Plateau, colerly led to further collecting, and in 1935 J. B. Reeside. lecting· vertebrate lrmnains from the beds earlier ex~ 

Jr., joined the writer in a visit to the _Wasatch Plateau amined by Reeside ~nd the writer. During the first half 

that established the presence in the "lower Wasatch'' of this work the W]riter joined the Smithsonian party. 

of indigenow:;-dinosaurian remains in considerable ·va- The n1aterial collered greatly augments the results of 

riety. Gilmore concluded. on study of these fossils that the earlier work, gi ing a much more definite picture of 

they represent a late Cretaceous fauna, probably Lance the dinosaurian fa~ na, ·and, most i_m. po.rtant,_ verifying 

in age. A short note announcing the discovery of the the Paleocene 11 agel of the bone-bearing strata above the 

dinosaurian Inaterial was published.8 di.nosaur zone. Stlfdies of these fossils py Gi-lmore and 

In this search the upper levels of the lower member Gazin confirm th~l conclusions as to age tentatively 

of the "Wasatch" formation yielded no dinosaurs but off. ered on the earli~r,_ less distin:ctive coli. ections. · 

they did yield a mammalian fragment, estimated by - The progressive alterations of ~he stratigraphic 

G. G. Simpson and C. L. Gazin to be worthless for pre- scheme arising out f these discoveries are now brought 

cise determination, but probably not Cretaceous in age. together in a revi ed section which seen1s to embody 

No physical basis for .regional subdivision of the beds no major uncertaifties. The n1ain points of the reconcerned was then recognized, nor has it yet been; the vision may be conci~~ly stated as follows: (1) Abandontop of the Cretaceous, indistinguishable by other than ment of the classifi<1:ation as Wasatch of the three units 

faunal means, apparently lies in the middle or upper formerly designat d as members of that formation; 

part of the beds formerly thought to constitute the lower (2) recognition of he basal conglomerate_of the former 

member of the Wasatch. lower member of t'e Wasatch formation as equivalent 

In 1936 Schoff 9 discovered in the Cedar Hills (see to the original Prife River formation, and dist-inction 

fig.l4) athick section of conglomerate, red beds, fresh- of the overlying part·of the lower member as the North 

water limestone, buff sandstone and gray shale, parts Horn formation; (3) establishment of the Flagstaff 

of which contain marine fossils of Colorado age. This limestone as an indiependent formation; ( 4) adoption 

section is equivalent to a succession of beds in the Gun- of the name Golto~1 formation for the upper member 

nison Plateau that had earlier been determined by the of t~e Wasatch fo ~ation as originall_y cla~sifie~; (5) 

writer td be the same as the unit under the basal con- naming the new u ut beneath the Price River In the 

glomerate of the Wasatch in th:e Indianola district, western districts. th~ In~ianola group, subdivid~d where 

observed in 1.932. To check the unexpected region~! feasible and undiffe1entiated w_ .. here not. ; (6) assignment · correlation brought out by this developn1ent, Schoff to the Cretaceous f 'all beds up to and including the 

and the writer examined several localities in the Gunni- highest dinosaur zo 1e, and assignment to ~he Paleocene. 

son Plateau, the Cedar Hills, and the Indianola district of the overlying p~rt of the North Horn formation. 

and verified the· conclusion that the western succession For easy compari~on with the previous scheme, the 

of conglomerates, red beds, etc., is ·equivalent to the 'resulting new sectl'on is diagrammatically presented 

marine Colorado of the Wasatch Plateau. It was also in figure 1.5. - . · 

found that these beds, to all appearance, are involved · · f d · s Spieker, E. M., Orog nic history of central Utah : Science, vol. 83, equally with the Jurassic in the ol Ing of the Gunnison pp. 62-63, 1936. 1 . . 

Plateau' and that the deformed contacts in the Wasatch o Schoff, s. L., GeologYil of the Cedar Hills, Utah: Ohw State Umv. Abstracts of Doc. Dissert. 25, pp. 375-386, 1937. 

Plateau do not demonstrate angular discordance,· the 10 Spieker, E. M., and ~eeside, J. B., Jr., Cretaceous ~nd Tertia_ry for- - mations of the Wasatch Ijlateau, Utah: Geol. Soc. Amenca Bull., vol. 36, 

earlier folding therefore probably did not penetrate the p. j4Jofi2~tatement concbrning the use of the term Paleocene seep. 135 

parts of central_ ...Utah here described, although the na- of this paper. 

668015- 46- 2 
122 

West 

GREEN 

. , ..) 

SHORTER CONTRIBUTIONS TO GENERAL 

THIS PAPER 

RIVER FORMATION 

- COLTON 

FLAGSTAFF I 

UMESTONE 

NORTH HORN 

. PRICE RIVER 

FORMATION 

GEOLOGY, 1943-45 

East 

FORMATION 

FORMATION 

Upper 

member 

Castlegate ss. 

·member 

STAR POINT SS. 

EARLIER REPORTS 

GREEN RIVE~ FORMATION 

Upper 

member 

Flagstaff Is. 

member 

Lower 

member 

Castlegate ss. member 

WASATCH 

FORMATION 

FORMATION 

BLACKHAWK FORM. 

STAR POIN,T ss: 

Upper sh. Upper sh. 

_1--E_m_-e_ry::__ss_._ MANCOS . Emery.ss. MANCOS 

~~~r~~ :.· SHALE SHALE ' ;~~r: ~ ::.· 

Lower sh. Lower sh. 

DAKOTA? SANDSTONE 

MORRISON FORMATION 

SAN RAFAEL 

GROUP 

DAKOTA? SANDSTONE 

MORRISON FORMATION 

SAN RAFAEL 

GROUP 

FIGURE 15.-Relationships of stratigraphic units across the Wasatch Plateau, showing equivalence with units described in earlier reports. 

Angular unconformities are show~ by wavy lines. 

REVISED STRATIGRAPHIC SECTION 

GENERAL FEATURES 

The rocks with which this paper is concerned range 

in age from Upper Jurassic to Eocene. The stratigraphic -units now recognized in this section are tabulated below. Two equivalent but notably different 

sections are found in the region, one in the eastern 

part of the Wasatch Plateau and adjacent parts of 

Castle Valley and the San Rafael Swell, and the other 

in the western part of the Wasatch Plateau and adjacent 

parts of the Sanpete and Sevier Valleys. As to actual 

boundaries of units the eastern section now stands un- ch~nged from the form earlier published/2 and it need 

12 Spieker, E. M., The Wasatch Plateau coal field, Utah: U. S. Geol. 

Survey Bull. 819, pp. 15-48, 1931. 

Tq,ble of formations, northern and western borders of Wasatch Plateau, Utah 

System Seriei" Group and formation · Chararter Thickness 

(feet) 

-- ---- Green River formation. Gray to green-gray shflle, oil shale, gray to buff sandstone, fresh-water li,OOO+ 

limestone. 

Eocene. 

Tertiary. Colton formation. Red shale, gray sandstone, with some gray and yellow shale and brown, 

green, and pink sandstone. , Q-1, 500 

Paleocene (?). Flagstaff limestone. - Limestone, gray shale, gray sandstone, some oil shale. . 30Q-l, 500 

Paleocene. 

Local unconformity 

North Hom formation. . . Variegated shale, buff to gray sandstone, conglomerate, some limestone. 50Q-2, 400 . Price River formation. Gray S!U).dstone, grit, conglomerate, loc.al gray shale. 70D-2, 000 

---Unconformity ---- Coarse gray sandstone, conglomerat-e, boulder beds in upper part. 400+ 

' Sixmile Canyon formation. Cream to buff sandstone, gray to black shale, coal; partly brackish water. 300 

ci. 

::l Coarse gray sandstone and conglomerate. 2, iOO 0 

Cretaceous. Upper Cretaceous. Sb ' Sandstone, cream, buff, brown, white, thin-bedded to massive, with in- ~ Funk Valley formation. tercalated shale; unit of gray shale 650 feet thick near middle; marine, 2,250 '0 

~ 

-

Niobrara in age. ~ 

;a Shale, gray, with thin layers of bentonite. gray limestone, and fine sand- ~ Allen Valley shale. 60Q-800 H stone; marine, Carlile in age. 

Sanpete formation. Sandstone, brown, buff, gray, fine to coarse; shale in thin beds; conglom- erate in upper and lower parts; largely marine. 1, 350 

·-- Morrison (?) formation. Gray sandstone, conglomerate, variegated shale. 1,050 

Q) 

Twist Gulch member. Siltstone and shale, red, in tbin-bedded succession, with many thin beds 05 3,000 

Jurassic. _Upper Jurassic. ~ of green-gray to white siltstone. 

~ Q) Shale, gray in lower part, with prominent red blotches in main part, deep ·s. Twelvemile Canyon member. red and salt-bearing in upper 500 feet: beds of sandstone and gypsum in 7,000+ ~ middle. , -< 

·' 
I . 

LATE MESOZOIC AND EARLY CENOZOIC HlSTORY O:F CENTRAL UTA¥ 123 

not be repeated here ; changes of nomenclature and age 

assignment in the Wasatch and Price River formations1 

as well as mutual equivalencies between . the eastern 

and western sections, are shown in figure 15. • 

In general the formations of the western section differ 

from those of the eastern section in characteristics that 

reflect greater proximity to mountains and the scene of 

mountain building. The Jurassic rocks are enormously 

thicker there than to the east, owing to their accumulation in a strongly down warping part of the Wasatch 

geosyncline. The rocks of Colorado age are not only 

thicker, but also coarser, and they bear witness to orogenic disturbance nearby to the west, showing rapid 

lateral change eastward from piedmont and other continental conditions to littoral and offshore marine conditions. Early and middle Montana time are not represented in· the area affected by Laramide folding, because 

of removal by" postorogenic erosion of uplifted sediments 

equivalent to the ~pper part of the Mancos, Star Point, 

and. Blackhawk formations, but in the central part of 

the western belt ·the Blackhawk formation is present 

and is similar lithologically to the eastern BlackhawK 

but thicker. As to the late Montana rocks, the Price 

River formation is generally thicker and coarser, culminating in these respects in the district south of Thistle, 

where it is. a very thick and prominent conglomerate. 

Above the upper Montana the formations of the western belt begin to resemble those of the east more closely, 

and the North Horn strata differ from their equivalents 

on the east front of the plateau chiefly in a· general 

though not complete absence of fresh-water limestone, . and consequently in a dominance of clastic sediments. 

In the parts of the belt closest to the source area the 

North Horn formatJon is ~ore brightly colored than to 

the east. The Flagstaff limestone of the western area 

differs largely in greater thickness, the Colton formation 

differs hardly at all, and except for the results of extensive jntertonguing between these two formations they 

are fairly uniform across central Utah. The Green 

River formatio:p. of the west shows local differences, having a greater content of limestone in some places and 

of coarse sandstones in other places, but on the whole 

it, too, is regionally much the same. 

JURASSIC SYSTEM 

REGIONAL NOMENCLATURE 

Jurassic rocks are exposed in the southwestern and 

northwestern border districts of the Wasatch Plateau, 

one area lying between Salina and the southern end· of the Gunnison Plateau and the other between Indianola and Thistle. The dominant unit in both areas 

is a thick mass of marine shale, with some fine-grained 

sandstone, salt, and gypsum, described below as the Arapien shale. Above the Arapien are variegated beds, 

sandstones and conglomerates, provisionally assigned to 

the Morrison formation, as shown in the general stratigraphic table. '-

The nomenclature of these rocks, and especially those 

here referred to the Arapien shale, presents a problem 

in that the area lies between two regions in which Jurassic strata probably equivalent in large part to the central Utah beds have been 'classified in two different 

schemes, both of which have been widelo used. Instead 

of being clearly correlatable_ with either of · these two 

sections, the strata of central Utah are in important respects different from both. To the north, in the W asatch and Uinta MountaiRs and ·adjacent country in 

. northeastern Utah and southwes'tern Wyoming, Jurassic nomenclature has been large~y derived from the section established by Veatch 13 for S~uthwe&ern Wy9ming, 

whereas to the east and south, i11 the Colorado Plateaus, 

the section of the San R-afael Swell ·has ·largely served 

as standard, and the stratigraphy has been worked out 

over a large area to a degree of accuracy rarely possible 

in geologic wor)r. ~ Although very complex in details 

of internal stratigraphy, the Jurassic section in its broad . outlines is much the same over the entire region, consisting of a basal unit of cross-bedded sandstone, probably continental in origin, a n1iddle unit of shale, sandstone, limestone and gyp~um, largely marine, and an 

upper unit of variegated beds, sandstones and conglomerates, continentar in origin. ,Wherever recognized the 

upper unit has been identified as the ·Morrison formation. In the Colorado Plateau the middle unit is the · San Rafael group, and it is roughly equivalent to the 

Twin Creek limestone as identified in . the Wasatch Mountains~ although this Twin Creek includes, in addition to the type Twin Creek, at least s'ome of the Beckwith formation of Veatch's original section for south_. 

western WyomingY The Nugget sandstone is probably 

equivalent to the Navajo .of the southern section. 

The Arapien shale of central Utah appears to corr·espond roughly with the Sa:rj.,:Rafael group but is much 

thicker and cannot be subqi~ided into units definitely 

correlatable with the formations of the San Rafael 

Swell. Inyiew o·f the striking lateral changes brought 

out by Baker, Dane, and Reeside for the large are~ to 

the east and south, it is not safe, 'Yith data now available, to bridge the gap of al;>Out 40 miles between Salina 

Canyon and the San Rafael Swell with anything more 

than a generalized correlation. To the north correla- . tion is likewise uncertain, although it is likely that the 

Arapien of the northwestern part of th~ Wasatch Plateau is equivalent in large part to the so-called Twin 

Creek of the central Wasatch Mountains. Extension of 

the name Twin Creek, considering the departure from 

the typical sense already evident in the Wasatch Moun:. · tains, is undesirable. Another element of uncertainty 

is introduced by the absence, in extensive and highly 

deformed exposures of Jurassi~ rocks in central Utah, of 

the basal sandstone unit that is uniformly present elsewhere, although this phenomenon may be explained on 

structural grounds. In southern and southwestern 

Utah, on the other nand, there is probably a considerable area in which the Arapien shale may be recognized. 

For these reasons the sec~ion as here described is not 

designated by any. of the preexisting terms available. 

ARAPIEN ~HALE . 

' . p DEFINITION, DISTRIBUTION, A}JD. GENERAL STRATIGRAPHIC 

RELATI~NS 

The name Arapien shale is here given to the body of 

red to gray shale and fine-grained sandstone, salt- and 

gypsum-bearing in part, referred to in existing publications 16 simply as Jurassic shale, which crops out prom13 Veatch, A. C:.~, Geography and geology of a portion of southw.estern Wyoming: U. S. ueol. Survey Prof. Paper 56, pp. 56-58, 1907. 14 Baker, A. A., Dane, C. H., and Reeside, .T. B., Jr., Correlation of the 

Jurassic formations of parts of Utah, Arizona, New Mexico, and Colo- -rado: U. S. Geol. Survey Prof. Paper 183, 1936. 16.Baker, A. A., Dane, C. H., and Reeside, J. B., Jr., op. cit., "P· 3. 16 Howell, E. E., U. S. Geog. and Geol. Surveys W. 100th Mer; Rept., vol. 3; pp. 175, 236, 1875. Dutton, c. E.; Geology of the High Plateaus 

of Utah : U. S. Geog. and Geol. Survey Rocky Mtn. Region Rept., pp; 153-154, 163-165, 1880. RichardsoW,-G. B., Underground water in San-· pete and central Sevier Valleys, Utalf'f'U. S. Geol . . Sur.vey Water-Supply Paper 199, pp. 8-9, 1907. Eardley;'A. ·J., Stratigraphy of the southern 

Wasatch Mouutains, Utah : Michigan Acad. Sci. Papers, vol. 18, pp. 330-

334, 1933. - ;., . 

/. 

/ 
124 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY,_. 1943-45 

ine11tly in a belt .2 to 3 miles wide on the east side of 

Sevier Valley along the margin of the Wasatch Plate.au. 

It begins at the southern end of Sanpete Valley, near 

the main highway about 5 miles ea~t of Gunnison, and 

extends southward past Salina to a point about 6 rnileEi 

southeast of Richfield. The name is taken from Arapien · Valley, which lies parallel to the base of the Wasatch 

Plateau about 6 miles southeast of Gunnison, and on the . west side of whi<th the formation is typically if not completely exposed. In all this area the upper limit of the 

formation has been found clearly exposed at only one 

place-in Salina Cariyon, where the overlying beds are 

the sandstone, conglomerate, and variegated shale of the 

Morrison ( ? ) formation. The base of the Arapien 

has not been found in the entire region south of the 

Wasatch Mountains. In the Wasatch Mountains near 

Thistle the limestone and shale that are probably correlative with the Twin Creek limestone of the central 

Wasatch overlie cross-bedded sandstone, the Nugget, 

but correlation of these beds with the Arapien is not 

precise enough to allow a .conclusion respecting the 

probable basal relations in the districts farther south. 

. In addition to the belt along th~ margin . of the . Wasatch Plateau, the Arapien shale occurs in scattered 

outcrops through Sevier Valley and in a continuous belt 

that extends along the western base of the Gunnis'on 

Plateau to the southern end of the Vv asatch Mountains, 

where the exposures at the foot of Mount Nebo have .been described by Eardley.17 There are also a few disconnected outcrops iP the district north of Indianola. 

On the west side of the Gunnison Plateau the upper contacf is exposed. There the overlying strata are conglomerates and sandstones with some freshwater limestone, which, as seen in reconnaissance, afford no evidence favoring -identification as Morrison, and which 

are tentatively regarded as belonging with the Indianola group (undifferentiated). On the east side of 

the Gunnison Plateau, due west of Wales, the uppermost Arapien also is present, overlain by sandstones 

and conglomerates of the Indianola group, which are 

totally unlike the Morrison formation but cleal'l_y resemble the continental beds· common in the Upper 

Cretaceous of the region. The uppermost Arapien 

is present also in the district north of Indianola, but it · is. poorly exposed and has been deformed to an extent 

that makes the determination of stratigraphic relations ' 

uncertain. Near Thistle the formation is overlain by 

strata like those in Salina Canyon, which may belong 

to the Morrison formation. 

LITHOLOGIC CHARACTER, SUBDIVISION, AND THICKNESS · 

/ The Arapien shale may be roughly divided into two 

parts, the lower of which is dominantly_gray, the upper 

dominantly red. This color distrihvtion is, in fact, 

characteristic of the Jurassic ro0ks of similar age 

throughout Utah. In the area covered by this paper 

, there are five different types of lithologic assemblage, 

in which .the order of succession, beginning with the. 

lowern1ost, is commonly but by no 'means regularly as 

follows: ( 1) Gray limestone, generally thin-bedded; 

(2) light-gray siltstone and shale, very thin-bedded, 

·with occasional thin beds of fin, ely rippled sandstone; 

(3) gray shale, argillaceous and gypsiferous, with irregular red blotches, which locally become dominant; 

( 4) compact red salt-bearing shale; ( 5 )'thin-bedded red 

siltstone· and shale w_ith many thin layers of greenish 

white siltstone and. occasional zones of gray sandstone, 

some of which is fairly coarse-grained. 

-The lower two gray units are 1nuc:h like th~ Carm.el 

formation of the San Rafael group. The third unit, 

which is the most obvious lithologic type in the Arapien 

shale of central Utah, is similar to parts of the Carmel 

at places. The red shale of the fourth unit is unusual 

among Jurassic rocks. of the general region. The up- .permost beds are like the thin-bedded red beds common 

in the older Mesozoic rocks of the Colorado Plateau, . and indeed are very similar to the Summerville formation, the uppermost unit in the San Rafael group. In 

parts of the area these strata reca}l the ~nt~ad.a s~l~dstone of eastern Utah. · These . htholog1c similantles 

give good reason to infer probable equivalence of the 

Arapien shale with the San Rafael group, but the agreement is not sufficient to justify using the San RafaeJ 

formational names. -

. As they-appear in some par~s .o~ the regio~, ~or ~x­ ample in Arapien Valley and VICinity, these distlnc~Ive 

lithologic types invite division of the Arapien s?ale Into 

members, but th(} attempt to trace or reco~Ize th~m 

regionally has yielded nothing but uncertainty except 

for 'the uppermost un.it, which is consiste~~ly prese~t

wherever the formatiOn has been recognized. This 

uppermost u~it · is here set apa:r~ as the Twist Gulch· 

member. It is defined as comprising the strata exposed 

on the north side of Salina Canyon above Twist Gulch · and lying between the compact red salt-bearing shale 

of Twist Gulch and the diverse str;ata of the Morrison 

( ? ) formation. · 

The basal limestone of the Arapien shale is present 

near Thistle,. near Nephi, and on the west side of the . Gunnison Plateau, but in the Sevier Valley no limestone · has been seen. As the base ·of the formation has not 

been recognized in the Sevier Valley, the lowermost 

strata may be present though not exposed, but the extent and diversity of the outcrops suggest that not much 

of ·the formation is concealed. The thin-bedded gray 

shale,· unit 2 of the foregoing list, appears to be the 

basal part of .the formation in much of the country 

a1:ound Arapien Valley, but to the north and "west, gray 

shale of this type is underlain by the blotched gypsiferous shale, unit 3, and it is difficult to make out any regular order of occurrence, partly because of the intricate 

structure. In the belt between the mouth of Salina 

Canyon and the southern end of Sanpete Valley, for 

example, ·some transvm se sections suggest anticlinal 

structure, with basal gray thin-bedded shale in the center of the belt, but others give no evidence of anything 

but direct succession of beds in descending ordeF westward. In such sections the lowermost unit exposed is the 

prominent belt of dark red salt-bearing shale that extends .from south of Salina to the mouth of the valley 

of Twelvemile Creek, east of Gunnison. On the theory 

of anticlinal structure this salt:bearing shale might be 

interpreted as equivalent to the salt shale of Twist' 

Gulch, although it is much thicker and more ::;aliferous. 

Northeast of Salina in the foothills of the Wasatch 

Plateau gray" shale of type 2 is interlayered with the 

dark red of the outer belt, in a position that seems, as far 

as the structure has been made out, logically basal. The 

common physical criteria for recognition of top and bottom of strata, applied where outcrops permit, give scattered accurate determinations of position, but when assembled these data afford no positive general result. 

. ' 11 Eardley, A. J., op. cit, 
LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL U'l'AH 125 

The writer's present inclination is to consider the saltbearing shale near Salina as basal, followed upward successively by blotched gypsiferous shale and more red 

salt-bearing shale overlain by the Twist Gulch 'member. 

This sequence of strata is grouped together in one mem.- her, here named the Twelvemile Canyon member because the outcrops in the valley of Tw,elvemile Creek 

west of Arapien Valley include all the distinctive lithologic types, if not a full section of the strata. 

Characteristie outcrops of the gray and blotched ·shales of the Twelvemile Canyon member are shown 

on plate 18. · The thickness of the Ar.apien shale is difficult to 

estimate but is probably more than 10,000 feet. The 

Twist Gulch member is measurable with fair precision 

in Salina Canyon, but elsewhere the intricate contortion of the strata prevents certain measurement. Many 

outcrops of the softer shale are so covered by products . o:f weathering that' observat-ion of attitude is impossible, 

and even digging to fresh rock does not often help; the 

homogeneity of the shale and the obscurity of bedding 

planes usually defeat recognition of structure. 

The Twist Gulch member is about 3,000 feet thick 

in Salina Canyon, as measured by plane table. This 

thickness, although accurate for the strata measured, is 

arbitrary in that the Twist Gulch member grades down- -ward into the salt-bearing shale of the Twelvemile Canyon member, and no definite boundary exists. Most of 

the uncertainty as to the thickness of the forrp.ation 

attaches to the Twelvemile Canyon: member. Conservative estimates based on the assumption of modified anticlinal structure for the belt northeast of Salina range 

between 5,000 and 7,000 feet. On the other hand, if 

the section is mQre or less continuous and the · ~ds are 

not arched in a major anticline, estimates based on different measurements indicate a thickness between 9,000 

and 10,000 feet. ·The actual thickness may lie between 

these extremes, although the writer is inclined to :favor · the higher figrtres rather than the lower. For the ~xposures on Salt Creek south of Mount ~ ebo, Eardley ls 

gives three different sets o:f figures, ranging in extreme 

between 3,000 and 11,000 feet. 

AGE AND CORRELATION 

Fossils have been found so far only in the gray unit 

of the lower member (unit 2 ·of page 124), and these, 

in preliminary examin-ation, are assigned by J. B. Reeside, Jr., to an Upper Jurassic age. They are most like ·forms in the Carmel :formation o:f the San Rafael group: 

The forms present are: Pentacnnus asteriscus Meek and 

Hayden, Ostrea striqilecula White, Trigonia aff. T. 

q'L(;adrangularis Hall and Whitfield, Camptonectes cf. 

C. ewtenuatus Meek and Hayden, Camptonectes c:f. C. 

stygi1JJs White, Volsella _subimbricata Meek, and Lyosmna sp. 

The red salt- and gypsum-bearing shale is unfossili:ferous, as is also the Twist Gulch memoer. Generaliz~d 

correlation of the Arapien shale with the San Rafael 

group and the Twin Creek limestone of the vV asatch 

Mountains is briefly discussed in the foregoing section on 

regional nomenclature. 

MORRISON(?) FORMATION 

Above the marine Jurassic and beneath the marine 

Colorado in the Salina Canyon section and in the section east of Thistle, there is a succession of variegated 

shales, sandstones, and conglom~rates. In an earlier 

paper 19 these beds of the Salina and Thistle districts 

were mentioned as possibly Morrison, and in later field 

work the writer cam to regard them as Morrison. No 

fossils have been found in the beds, and identification 

was based on their stratigraphic position and lithologic 

character . . However, now that the sam.e lithologic 

character is known to be common in the Indianola group, 

which cohstitutes the western facies of the basal Upper Cret_aceous, the correlation of the beds of the Salina 

and Thistle districts is much less certain, and they 

are here designated as the Morrison ( ~) formation. 

~n the Salina district the unit is about 1,300 feet thick 

and consists of variegated shale, red, pink, and violet, 

commonly blotched with yellow; gray, gree~ish-gray, 

and ochre shale; brown, gray, and white sandstone; and 

conglomerate containing many-colored pebbles of chert 

and quartzite, whose maximum size is between 2 and 4 

inches. In the Thistle district the· lithologic character 

is similar, and the .unit is some'Yhat thicker. The thickness is not exactly known_, oiWing to conditions of out- ~rop and changes in dip, but it is probably about 1,800 

feet. Elsewhere in the western part of the Wasatch 

Plateau and in adjacent valleys no strata have ever been 

assigned to the Morrison formation, but it is possible 

that se'me of the conglomerates and red beds included 

in the Indianola ·group (undifferentiated) are the same 

as the unit here designated l\1orrison ( ~). -

No fossils having been :found, the local evidence comprises facts of lithology and stratigraphic position. ·The 

beds in question are in the approximate stratigraphic 

position regionally occupied by the Morrison formation. 

In arddition to the· general M·orrison-like ·aspect of the 

beds, lithologic evidence on the question includes three 

outstanding facts. First, the conglomerates of the unit 

in Salina Canyon contain notable quantities of black, 

green, and brown chert, a mineral that is distinctive in 

the Morrison_ conglomerates of the northern San Rafa~l 

Swell; whereas the Indianola conglomerates as a whole ~ontain little or no chert. Second., the contact between 

these beds and the under-lying Arapien shale in Salina 

Canyon, the only place in the 'Vasatch Plateau where it 

is exposed, is by no means clear-cut, but rather suggests 

intertonguing; above the first few feet of yellow sandstone, ochre shale, and conglomerate are thin-bedded red 

and_gray shales just like those of the Arapien. Third, 

the variety and succession of the beds in Salina Canyon 

are not ~xactly like those of the Indianola; this unit 

contains :ho fresh-water limestone, and the variegated 

beds are notably paler, more delicate in tint, than those 

of the lower part of the Indianola in districts to the 

north. 

Ip. the Salina Canyon section not only is the basal 

boundary of Morrison ( ~) indefinite, but its upper limit 

is likewise difficult to determine; and the same is true 

in lesse:r degree of the relations on Lake Fork near 

Thistle. A boundary has been drawn at the line 'of 

greatest apparent change between the colored rocks of 

.Morrison aspect and the doD?-inantly buff and gray rocks 

of the type common -in the regional Upper Cretaceous, 

but there is no clear-cut line of division. Furthermore, 

in the Salina Canyon· section ochre sandstones and 

tinted beds exactly like . those common in the Morrison 

(?) formation appear above the lowest fossil-bearing 

beds of Colorado age, and' such lithologic distinction as 

18 Eardley, A. J., op. cit., pp. 310, 330, 331. __ 19 Spieker, E. M., and Reeside, J. B., Jr., Upper Cretaceous shore line 

in Utah: Geol. Soc. America Bull., vol. 37, p . 432, 1926, 

.I 

/ · 
126· SHORTER CONTRIBUTIONS TO GENERAL. GEOLOGY, 1943-45 

· tliese types of strata might be thought to have 'is apparently of little or no significance. . · · As to regional evidence, the Morrison formation has 

been widely recognized in the Colorado Plateaus east 

of the Wasatch Plateau, and. existing knowledge of it 

has been ably summarized by Baker, Dane, and 

Reeside.20 The isopach map presented by these authors 

shows the formation thinning rapidly in central-southern Utah toward a western limit which, projected northward, would fall west of the area here considered. East · of the Wasatch Plateau the Morrison thickens toward 

the noi'theast to a kn~wn maximum of 847 feet, but in 

the entire distribution of the formation across eastern 

Utah there is- no suggestion of thickening toward the 

Salina area, where the thickness of the unit in question 

is greater than any so far rec9rded for the Morrison in 

the general region. _ : 

More important than th~ mere distribution of the 

beds, in the · present searcl;LfJ>r jnformation, is the ques- . tion of the source and diK~Ction of distribution of the 

Morrison sediments. If the source were the same as 

that of the underlying marine Jurassic sediments, 

dominantly to the west, it would seem that the forma:-

tion ought to have been deposited in the belt west of 

Castle Valley, where the thickest section recorded for 

the Colorado Plateaus is present.21 The conglomerates 

of the formation in Castle Valley, in a normal distribution of such sediments, should continue westward, 

toward the source; complete bypassing_ of gravel$ across 

such destructible material as the marine Jurassic sediments is difficult to visualize without more evidence of 

erosion than appears bet we~ the Ara pi en shale and the 

Morrison (~),for example, of the Salina district. Published accounts of the formation in the Colorado 

Plateaus contain no conclusions as to its source and 

distribution. Evid,ence known to the ~riter suggests 

a western or northwestern source, but this is not well 

enough worked out to justify discussion. 

Review of this evidence leads to no satisfactory conelusion, but at present the facts in favor of identification as Morrison seem to outweigh somewhat the opposing facts, and rather than adopt an alternative 

nomenclature which would app~ar to deny the presence 

of the formation in the region, it seems best to designate 

the beds by the qualified term Morrison ( ~) . . 

CRETACEOUS SYSTEM 

GENERAL CHARACTER AND DISTRIBUTION 

Rocks of Upper Cretaceous age are extensively . exposed in central Utah. They occupy large parts of the 

surface in the Wasatch and Gunnison Plateaus and in 

the Cedar :Hills, as well as in the valleys adjacent to these 

higher lands . . Although the exposures are by' no means 

continu·ous, most of the higher formations can be traced 

across the area with little interruption, and in general 

the conditions for the determination of stratigraphic 

relationships are favorable'. The rocks are dominantly clastic, and in general they 

are finer-grained on the east and coarser-grained on the 

west, a natur_al result of their derivation from high la1id 

masses to the west. They-are divisible into two_major 

groups. The lower group includes the Mancos shale and 

the Star Point and Blackhawk formations in the easterp 

part of the area and the Indianola grqup in the western 

part.- (See fig. 15.) _The upper group includes the · Price River formation and part of the North Horn formation. These two major groups are separat~d by the . 

unconformity that resulted from the main folding of 

the Wasatch Mountains-an angular unconformity in 

the western part of the area and a disconformity in the 

eastern part. As a rule, ~he lower unit is composed of 

marine beds that grade upward to continental beds, the 

whole dominantly buff and gray in color; the upper 

unit, in central Utah, is almost exclusively continental 

in origin and contains noteworthy amounts of varicolored beds in the upper part. Notable exceptions are 

the abundance of coarse continental sediments and red 

beds in the lower· unit of ·the westernmost part of the 

·area, and the presence in the lower part of the upper 

unit of thin brackish-water beds, but on the whole the 

two units are distinct as to the features named. 

INDIANOLA GROUP 

DEFINITION AND NOMENCLATURE 

In the western part of the Wasatch Plateau the rocks 

of Colorado age form a 'heterqgeneous assemblage of 

conglomerate, sandstone, shale, and limestone, of both 

marine and continental origin, showing a wide range in 

color and, in parts of the region, abrupt lateral change 

between extremes in rock types. These strata, witlfout 

exception, occur within isolated areas in the folded belt 

at the \vestern· base of the plateau, and COl''relation · between the different areas has involved a group of 

problems whose general nature ·is o-utlined in the first 

part' of this report. Because of the significance in the 

regional geology of the correlations now established, .it is desirable to make clear those elements of the field 

evidence on which the conclusions are mainly based .. 

¥arine strata of Colorado age h~ve long been recognized .~tt three localities on the western border of the 

'Vasatch Plateau-Salina Canyon, Sixmile Canyon) 

and Lake Fork east of Thistle .. These strata are -of the 

lithologic type normal for the Upper Cretaceous of the 

Colorado Plateaus and adjacent regions to the eastgray, buff, and brown sandstones and shales, with some 

conglomerate-and in the present study they were found 

to be subdivisible into definite lithologic units that parallel, at least approximately, the major faunal divisions 

of the Colorado. In all three localities they underlie 

younger shata jn a:ngular unconformity. 

In Sixmile Canyon and on Lake Fork the lowest formation above the unconformity is a conglomerate, formerly classified as the basal conglomerate of the 

Wasatch formation but . now identified as the Priee 

River formation. -At three localities within a radius 

of 4 miles north o:f Indianola this same conglomerate 

overlies, in angular uneonformity, another conglomeratic assemblage of rocks that contains prominent units 

of brilliantly colored shales and sandstones, with some 

fresh-water limestone. At the three areas in the Indianola district the strata are differ~nt, as deseribed farther on, and the only characteristic they have ih epmmon 

is their occurrence beneath the conglonl'erate at the base 

of the Price River formation, which may be_ traced 

through the district with slight ehance of error. 

At the northernmost of these outcrops, on Dry Creek, 

a sandstone at the top of the section there exposed contains 0 orbula nematop7wra, a member of the · Colorado 

fauna. Although local proof is lacking, regional evidence shows .that this sandstone is stratigraphically a 

20 Baker, A.· A., Dane, C. H., and Reeside, J. B., Jr., op. cit., pp. 9, 47, 

55. fi~r. 14. . 21 Gilluly, .Tames, and Reeside, J . B., Jr., Sedimentary rocks of the Sian 

Rafael Swell and some adjac'ent areas in eastern Utah ; U. S. Geol. 

Survey Prof. Paper 150, pp. 81, 91-92, 1928. 
/ 

LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL UTAH 127 

part of the variegated sequence on Hj~rk Creek, to the 

south. In the east Jront of the Gunnison Plateau ·the 

Price Riv~r conglomerates may be recognized, with the 

North Horn and Flagstaff formations in characteristic 

development above. Beneath the Price River, i:t;J. a~lguhtr unconformity (see fig. 16) i~ the sam.e S<?rt of ht~ologic assemblage as in the I;ndianola distnct, lackn:g 

only marine beds, as far as IS known from reconnaissance observation. _This belt of outcrop may be traced~ 

southward, with some interruptions, into the foothills 

of theW asatch Plateau northeast of Salina, where again ·the strongly colored shales, con~lomera~es and fr_eshwater limestones are only 31j2 miles from the buff and 

aray marine Colorado in Salina Canyon. The same 

~trata may be recognized also on the ~est side of ~he Gunnison Plateau, where the angular discordance w.Ith 

the overlying Price River is slight, but the successiOn 

otherwise .is similar to that of the east front; Traced 

northward these strata are continuous as far as the 

Cedar Hill~, where Schoff 22 has found them to contain a 

marine zone with a diagnostic Colorado fauna. The 

section in the Cedar Hills is very thick and, although 

parts of it are not well exposed, the marine zone is 

clearly intercalated betwee~ conglomer~te and red~bed 

facies that are continuous with the beds ur the Gunnison 

Plateau. There remains -to be closed only , the, gap 

between the Cedar Hills· and the Indianola_ district, 

where the nearest outcrops are 8 miles apart: The sum 

of the facts outlined above leaves little room for doubt 

that the beds of the Indianola district are equivalent to 

those in the Cedar Hills and hence to the others in all 

the above-mentioned districts bordering Sanpete· and 

Sevier Valleys. 

The ~pparently incongruous assemblage~ in ~hese 

several sections are thus brought together In a Singl~ 

a ross unit. In the Thistle, Sixmile, and Salina Canyon areas this unit, truncated by the Price River and 

younger' formations, is clearly divisibl~ in~o t~e San 

pete, ~lien Val~ey, Funk yapey, .an~ SI~mile Canyon 

formatiOns, but In the Indianola distnct, In the area between Salina and Gunnison, i_n the Gunnison .Platea~, 

and in the Cedar Hills such units as now -seem differenti- able fail to correspond well enough with the formations 

of the other districts to justify a named subdivi'Sion ~ 

The--writer t_herefore proposes that the entire unit be 

called the Indianola grou_p, subdivided into formations 

where consistently possible, undifferentiated where not. 

(See pl. 19, A.) The Indianola district, which is designated as the type area, contains representatives of all 

three major lithologic types now known· in the Upper 

Cretaceous of· the region-(1) buff and gray marine 

beds, on Dry Creek about 41h miles no~th of In?-ia~ola, 

(2) buff and gray ~ontinental b~ds on Little Clear Creek 

about 2 miles northeast of Indianola, and (3) conglomerate, variegated beds, and freshwater limestone _on 

Hjork Creek about 3 mil~s north of !ndianola. !'he 

lower conglomerates on _liJork C~eek, In the .Gunnison 

Plateau, in the Cedar Hills, and In the foothips northeast of Salina are thought to be roughly equivalent to 

the Sanpete formation, and they may also be equivalent 

to the strata in Salina Canyon and near Thistle, which, 

however, have b_een described as Morrison ( ~) forma- tion. The marine zone on Dry Creek and in the Cedar 

Hills probably correlates with the Funk Valley for:t?a - tion. The upper conglomerates of the Cedar Hills 

and the Gunnison Plateau and the buff beds on Little 

Clear Creek probably represent the Sixmile Canyon 

formation. 

SANPETE FORMAT~ON 

·The basal rocks of the Indianola group in parts of 

the western marginal belt form a distinct unit of sandstone and conglomerate, with minor amounts o~ shal~, . 

containing fossil~ of lower Colo~ado age. Thi.s unit 

overlies the MorriSon ( ~) formatiOn and underlies the 

Allen Valley shale. - Where clearly differentiable, it is 

set apart as the Sanpete formation, named from Sa~­

pete Valley on' the east side of which, south of Manti, 

the rocks ~f the formation are exposed · in hogbacks 

and low ridges. The formation is expo.sed also ~n Salina Canyon a-bout 4 miles ·east of Salina and In the 

canyon of L~lm Fork about 1~. miles -southeast of - Thistle. Eqmvalent stra~a occu~ In the lower part of 

1 the Indianola group ( undifferentia~~). · _ The only one of the three localities t~at affo_rds .a 

complete and well-exposed se_ytion of the fo~matiQn ~s 

Salina Canyon, where it is about 1,350 feet,thiCk: Tln~ 

figure is given as approximate because of the difficulty 

in determining a reasonable boun~ary betwe~n the Sanpete and Morrison ( ~) formatiOns, as di?cussed on 

page 125. The lower 335 feet of the for!llatwn as here ~peci:fied may belong with the Morrison (~). ~he ~op 

of the Sanpete formation is exposed at the type locality 

and in Salina Canyon, and it is easily defined. 

The formation consists of brown, ochre, buff, and 

gray sandstone -gray to ochre shale, mainly sandy, and 

gray conglome~a:te. Conglo!llerate is fairly abunda;nt 

in the lower part but absent In the upper. part .. Fossils 

have been found in the upper part only In Salina Canyon, where the lo:yvest fossili.ferous zone is a~out 90 f~et 

below the top of' the formaflon, but ne~r T~nstle fossils 

are abundant in the lower part, which IS there less 

conglomeratic. _ · · On the east strata equivalent to the Sanpete fort?ation comprise the basal unit of the M;ancos shale, which 

in Castle Valley 23 is dark-gray manne shale, and P.ossibly also the Dakota ( ~) sandsto~e. The _format10!1 

represents a· n~ar~shore zone of dominantly coarse sediments intermediate between the open sea to the east 

and a mountain-front belt of coarse gravel fans to the 

west. A similar facies, but not so coarse, has been recognized in the Coalville district,24 to the northeast, and 

in the Kolo_b Plateau,25 to the southwest. 

ALLEN VALLEY SHALE 

Between the sandston~ of the Sanpete and Funk 

Valley formations is a body of marine shale, 600 to ,800 

feet thick, here designated the Allen Valley shale. Tl_l·e 

type locality is at the base of the Wasatch Plateau, In 

Allen Valley, a narrow longitudinal valley separated 

from Sanpete Valley by a pronounced hogback o.f 

Sanpete formation, a?out ? miles .souti;west of Manti. 

Most of the outcrop In this area IS t~Inly cover~d by / 

soil but a good exposure of the entire formatiOn Is 

affo'rded by an irrigation ditch, in the SW1,4 sec. 26, 

T. 18 S., R. 2 E., Salt Lake meridian, near the head , of Allen Valley. The structural position of the Allen 

Valley shale in Sixmile Canyon is show~ in figure 1.7. 

The · only other outcro_P of the formatwn. k;nown In 

central Utah . is in Salina Canyon. where It Is. partly 

22 Schoff. S. L .. Geolog~· of the Cedar Hills. Utah (unpublish.ed notes). 2a Lupton, C. T., Geol o!!.'v and coal resources of Castle Valley m Carbgn. Emery,_ and Sevier Counties, .Utah: U. S. Geol. Survey Bull. 6'28, p. -6, 

1916. . 24 Weg-emann, C. H ., The Coalville coal field, Utah: U. S. Geol. Survey 

Bull. 581, p . 163; 1915. . · 2s Richardson, G. B., The Upper Cretace?us ~ection m the Colo.b P!~­

teau, southwestern Utah : Wash. Aead. Sci. Jour., vol. 17, pp. 464-41 o. 1927. 

'-

'{-
1,28 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY., 1 9 4 3-4 5 . 

exposed in a narrow strip on the north side of the 

canyon about 5 miles east of Salina; there the top and 

base are well exposed. 

The Allen Valley shale is fairly uniform in general 

aspect; it consists largely of evenly bedded gray marine 

shale of the type common in the regional Upper Cre-·· taceous. In detail it exhibits· some variety; the shale 

is interbedded with thin layers of yeJlowish bentonite, 

siltstone, very fine-grained sandstone, and gray limestone. No individual bed is more than a foot thick. 

The shale ranges in texture from impalpable to very 

sandy. At the type locality the formation is 620 feet 

thick, and in Salina Canyon it _is 850 feet thick. · Fossils from the Allen Valley shale, identified by 

J. B. Reeside, Jr., are of middle Colorado (Carlile) 

age; and indicate that the formation is to be correlated 

with the Ferron sandstone, a member of the Mancos 

shale in Castle V .aney.26 This indicates an embayment of the Mancos sea west of the peninsular land 

and shoal area in which the Ferron was deposited. 

Shale of the same age has been found in the Coalville 

region, and in southwestern Utah; 27 it is not unlikely 

that the formation is widespread in & belt trending a 

little east of north through central Utah. 

FUNK VALLEY FORMATION 

The Allen Valley shale is overlain by marine sandstone and shale of Niobrara age, which fonn a unit about 

2,250 feet thick, here named the Funk Valley formation. 

The type locality is in the ridges bordering Funk Valley, 

in sees. 34 and 35, T. 18 S.~ R. 2 E., Salt Lake meridian, 

3 to 4 miles southwest of Manti. (See pl. 19, B.) The 

formation is exposed more extensively than the others 

of the Indianola group in the Manti area; it forms the 

marginal foothills of the "\V asatch Plateau for more than 

4 miles south of Crystal Spring. In Salina; Canyon the 

basal600 feet of the formation is exposed. In the Cedar 

Hills, just east of the southern Wasatch ~1oui1tains, 

Schoff 28 has found 1narine sandstones that are probably 

equivalent to part of the Funk Valley formation. 

Nonmarine strata of the same age are probably 

abundant and widespread in the Indianola group 

(undifferentiated). 

At the type locality the formation consists of three . clearly separable members : ( 1) a basal series of sandstones with thin interbedded shale, about 900 feet thick; 

(2) a middle unit of gray marine shale, 650 feet thick; 

and ( 3) an upper sandstone 700 feet thick. The sandstones range in color from white through cream and 

buff to brown. The position of the formation in the Sixmil~ Canyon section is shown in figure 17. · · Fossils frmn the two sandstone members are of Colorado age, substantiating the natural inference from ~tratig;raphic relations that the Funk Valley formation 

1s equ.1valent to the part of the Mancos shale immediately above the Ferron sandstone member in Castle 

Valley .. Like the Allen Valley. shale, the Funk Valley 

formatiOn has , counterparts 111 both the Coalville- . Ev.anston and Kaiparowits-Kolob regions, but correlatiOn over the rather long stretch between these areas 

is 1~ot ·yet precise enough to justify extension of 

nomenclature. . · 

. SIXMILE CANYON FOR:r.{ATION 

' . 

, ~J~Sixmile Canyon east of the Funk Valley formation i~ a thick sucqession of coarse-grairied gray sandstone 

and conglomerate containing a coal-bearing member of 

finer grain. To this succession the nam~ Sixmile Canyon· formation is here applied. This unit has· not been 

recogni,zed at any other place in the vVasatch Plateau, 

but, like the underlying formations of the Indianola 

group, it is probably represented at some localities where 

the group is not subdivisible. In Sixmile Canyon three 

members are recognizable-(!) a prominent gray conglomeratic sandstone about 2,000 feet thick; ( 2) a coalbearing member containing .gray to cream-colored and 

white mainly fine-grained . sandstone, gray to white 

shale, carbonaceous shale, and coal, about 300 feet thick; 

and (3) an upper member of conglomerate and conglomeratic sandstone of which 425 feet is exposed. The 

top of the formation has not been seen; the uppermost 

strata in the section measured are -the highest beds 

exposed under the lower angular uncorrformity in Sixmile Canyon. (See fig .. 17.) 

Until 1935 the strata now assigned -to the Sixmile 

Canyon were thought . to be late Montana in age . and 

'vere correlated with the Price River formation. 29 In 

1935 and 1936 fossil plants and mollusks collected from 

the coal-bearing member were . determined by R. '\V. 

Brown and J. B. Reeside, Jr., to be of Colorado age. 

This fixes the ag.e of the lower. member as Colorado. 

The upper member has yielded no fossils and its age 

is not proved, but it is similar for the most part to the 

lower member and is apparently not separated from the 

middle member by any break other than the change in 

lithology, which is itself not sharp; it is therefore provisionally included with the underlying beds and interpreted to be of Colorado age. It might p'ossibly be 

of early to middle Montana age,. but not late Montana, 

because rocks of that age overlie the angular unconformity. 

The change in age assignment of this formation has 

resulted in a new interpretation of the late Montana 

stratigraphy and the orogenic history of central Utah, 

as is brought out in the parts of this report-devoted . to those subjects. It has also brought the coal-bearing 

member of the Sixmile Cany<:?n formation into closer 

coordination than before with the regional pattern of 

coal occurrences. ·\'Vestward and southwestward across 

Utah the coal-bearing rocks of the Upper Cretaceous 

appear at successively lower levels; ·the coal beds of 

the eastern Book Cliffs are of late J\ifontana age, those of 

the Wasatch_ Plateau of middle Montana, and those of 

Castle Valley and souther:n :Utah of'Colorado age. In 

the main body of the vVasatch Plateau the strata of 

late Montana age contain no coal. Considered as late 

Montana the ·coal of the Sixmile Canyon formation was 

somewhat incongruous in this scheme; as late Colorado 

it is in better accord. 

INDIANOLA GROUP (UNDIFFERENTIATED) 

The discussion of the Indianola group thu~ far pre- . sen ted has necessarily brought out many of the important characteristics of the unit for those areas where it 

is not differentiated. There need be added here only 

26 Spieker, E. M., and Reeside-, J. B., Jr., Upper Cretaceous shore line 

in Utah: Geol. Soc. America Bull., vol. 37, pp. 432-435, 1926. · · 21 \Vegemann, C. H., 'l't.e Coalville coal field, Utah: U. S. Geol. Survey Bull. 581, pp. 161-184. 1915. Richardson, G. B., Reconnaissance of the 

Book Cliffs coal field: U.S. Geol. Survey Bull. 371, 1909. ' Reeside, J. B., 

Jr., in Gregory, H. E., and Moore, R. C., 'l'he Kaiparowits region: U. S . Geol. Survey Prof. Paper 164, n. 113. 1931. 28 Schoff, S. L., Geology of the ~edar Hills, Utah (unpublished notes). 2ll Spieker; E. l\1., and Reeside, J. B., Jr., Upper €retaceous shore line 

in Utah: Geol. Soc .. America Bull., vol. 37, p. 433, 1926. Richardson, 

G. B., Coal in Sanpete County, Utah: U. S. Geol. Survey Bull. 285, p. 281, 

1 906·; Underground water in Sanpete and central Sevier Valleys, Utah : U. S. Geol. Survey Water-Supply Paper 199, p. 9, 1907. 
LATE MESOZOIC AND EARL CENOZOIC HISTORY OF CENTRAL UTAH 129 

~ 

Q) 

Q) 

NW. () SE . 

1... ..:( 

Q) 113 

~ · Cb-

~ 9000 

8000 

and across divide to Little Cleare{reek 

I A 

Gunnison Plateau 

7000-

I 

q 

Sanpete Valley 

2Miles 

;IGURE 16.-Cross sections showing elations Qf .A.rapien, Indianola, and Price River strata in northern Wasatch Plateau and central-eastern Gunnison Plateau. 

Qal. Alluvium. I KTn. No•th Horn fo•mation. 

Tv. Volcanic rocks of uncertain Kp. Price River formation. 

age, possibly mid-Ter iary. Ki. Indianola gronp. Tf. Flagstaff limestone. .Ja . .A.rapien shale. 

a somewhat more specific description of lithologj and 

a brief discussion of age. [ 

The three facies of the Indianola-buff and gray marine, buff and gray continental, and red-bed con~inenta~-are ,exposed in Dry Creek, Little Clear Creeki, and 

H]ork Canyons. (See p. 127.) These three locJlities 

are separated by faults, in an area of rather co91plex 

structure (see fig.16), anc;l it is impossible to work 1out a 

completely connected section among them. The rain 

outlines of the section, however, seem fairly clear. 01} . Hjork Creek beneath the angular unconformit are 

about 2,000 feet of strata in contact, probably 1 sedimentary, with the Arapien shale; these beds probably 

represent the lower part of the Indianola there. l On 

Dry Creek are conglomerates and sandstones, probably 

between 2,000 and 3,000 feet thick, with a marine zone 

at the top that is estimated to .be about 7,000 to ls,ooo 

feet above the basal beds of Hjork Creek. This otal is similar to the thickness of the group in Sixmile Canyon, and it may represent most of the unit in th Indianola district; but 15 miles to the southwest, i:h the 

Cedar Hills, Schoff 30 has found nearly 15,000 feb

1 

t of 

strata that seem to belong to the Indianola group, and 

it is probable that the section north~ of Indianola is 

incomplete. 

668015-4~3 

On the ridge east of Little Clear Creek is a considerable area of Indianola strata whose stratigraphic relations are not entirely clear. They are mainly buff and 

brown sandstone and conglomerate with gray shale, and 

they differ strongly from the beds on Hjork Creek, although they are similar to some of the beds on -Dry 

Creek. As the structure is now interpreted, some of the 

strata in this outcrop seem t0 belong in the lower part 

of the Indianola group, but some appear to underlie 

the Price River in structural position, which suggests 

that they are in the upper part. Neither the apparent 

thickness nor the lithologic aspect of the beds agrees 

with the hypothesis that the entire group is present.' 

All that can now be said is that the strata east of Little 

Clear Creek belong in the Indianola group, but their 

precise position is undetermined. 

The strata on Hjork Creek represent well the conglomerate-variegated bed facies of the group; and to 

give some idea of the lithologic types in this aggregate, 

which is the only facies of the three not elsewhere described, the following roughly grouped section is , 

offered. 

30 Schoff, S. L., Geology of the Cedar Hills, Utah (unpublished notes). 

. . 

• 
• 

130 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

J Sect:ion of India11ola strata exposed on Hjork Greek, sec. 21, T. 

11 S., R. 4 E., Salt Lake Meridian · • 

Price River formation. 

Angular unconformity. 

Indianola group: 

1. Sandstone, cream to buff, medium-grained to 

slightly conglomeratic, interbedded with shale, 

red, sandS----- -----------------------------

2. Shale, deep red to gray, with interbedded sandstone, brown, medium-grained ________________ _ 

3. Conglomerate, gray to red, pebbles and boulders of 

/ quartzite and limestone, average 4 inches but 

many are more than 1 foot in diameter ; some interbedded red sandstone and shale ______ ____ _ 

4. Shale, sandstone, · and conglomerate, brilliantly 

colored in various shades of red and purple; lime- stone, gray to white; sandstone, gray, fine, calcareous __________________________________ _ 

5. Sandstone, brown to buff; conglomerate; shale, dark gray __________________________________ _ 

6. Shale, orange, vermilion, maroon, gray ; sandstone, 

brown to gray; conglomerate and limestone in irregular beds __________ ____________________ _ 

7. Conglomerate, brown to gray; interbedded red 

sandstone and shale ; gray shale _________ ______ _ 

Arapien shale. 

· Feet 

65 

75 

100 

720 

50 

450 

600 

2,060 

The contact between the Indianola and Price River 

units is shown in plate 21, B, and the general relations 

on Hjork Creek are shown in figure 16. 

The age of the Indianola group (undifferentiated) is 

only partly known. The marine zone heretofore mentioned as containing fossils of Colorado age occurs in 

the upper part of the unit, and the age of the underlying 

strata is not definitely known. Among the areas where 

the group has not been subdivided the marine zone has 

been recognized at two places only-on Dry Creek, w~ere 

it is the uppermost unit exposed, and in the Cedar Hills, 

where it is about 2,500 feet thick. The base of the marine zone is about 9,400 feet above the base of the group 

and its top is about 2,800 feet beneath the angular unconformity at the locality of maximum known thickness.31 

At both these places there is no evident basis for setting 

off the lower beds, and where the marine zone has not 

been recognized the whole thickness identified as Indianola, heterogeneous though it is, seems to make a fairly 

consistent unit. For these reasons the beds below the 

marine zone are included with ih and the whol-e is regarded tentatively as upper Cretaceous in age. 

ROCKS OF EARLY AND MIDDLE MONTANA AGE 

On the west side of the Wasatch Plateau no rocks 

definitely identified as equivalent to the upper part of 

the Mancos shale and the St-ar Point are exposed. The 

Blackhawk formation, of Iniddle Montana age, is exposed east of Mount Pleasant, on Twelvemile Creek, 

the next creek south of Sixmile, and in Salina Canyon,32 

and at all these places it is similar to the typical Blackhawk of the east front of the plateau. It is unnecessary, 

therefore, to describe it here, but attention may be directed to the fact that the westernmost Blackhawk rocks 

exposed are no coarser in grain than those to the east. 

This suggests that by middle Montana time the highlands from which the coarse sediments of Colorado age 

were derived had been worn down. The total thickness of the Blackhawk formation in the western belt 

is not known, but zones of the formation have been tentatively recognized in the records of borings, which suggest 

that the formation is not much, if any, thicker t~a~ in 

the Pleasant Valley district and west of Huntington 

Canyon.33 It see1p.s likely that by middle Montana tirrie 

the rate of subsidence in the geosynclinal bert11ad slowed 

down. It might also be noted that the western outcrops 

of the Blackhawk formation are so close to the belt of 

Laramide folding that the original presence of early 

and middle Montana sediments in the folded belt seems 

almost certain. 

PRICE RIVER FORMATION 

DEFINITION AND LITHOLOGIC CHARACTER 

The Price River formation was originally defined 34 

to include the strata in Price Canyon above Castlegate 

between the Blackhawk formation and the former lower 

. · n1ember of theW asatch formation, now the North Horn 

formation. It consists there mainly of medium- to 

coarse-grained sandstone, with some grit. an~ ~ongl?merate and a minor amount of shale, and IS divided Into 

two members. The Castlegate sandstone member is separated from the upper member solely because of its 

cliff-forming habit, which gives it great regional pr.o~­

inence; lithologically the two mell!ber.s are closely similar. In Price Can <?n the format:on IS abol!t 1,100 feet 

thick. The lithologic character IS shown In plates 20 

and 21. 

DISTRIBUTION AND STRATIGRAPHIC . RELATIONS 

The Price River formation crops out throughout the 

Wasatch Plateau and in adjoining regions to the west 

and east. Its most notable known extension outside of 

central Utah is in the Book Cliffs, where the Castlegate 

sandstone member is recognizable as far east J as the 

Utah-Colorado boundary. 

In the eastern part of theW asatch Plateau t~e Cas.tlegate sandstone overlies the Blackhawk formatiOn without trace of angular discordance, but in many places 

where the contact is exposed there is .evidence of disc?nformity · the Castlegate was deposited on an erosion 

surface ~f very low relief cut i~to the ';1-ppermost Bla:c~­ hawk rocks. This disconformity was Interpreted origi--

nally to mean hiatus 35 and probably also ·disturbance 

somewhere to the west, although at the time it was not 

thought to represent the main folding of th~ Wasatch 

Mountains. The contact, even though eroswnal, ap- . 

peared too unifor~ in .the eastern Wasatch ~lateau ~nd 

the Book Cliffs to signify profound or extensive eroswn. 

On the other hand, the change in sediments between 

Blackhawk and Castlegate, and especially the sharpness 

with which coarse sands and grits appear above the 

cdntact, evidently signifies a notable change in th~ 

physiography of the souree area. . . T.he upper limit of the Price River formation. has 

always been difficult to set, be?ause the. coarse-grau~ed 

gray sandstones grade upward Into and Interfinger with 

the variegated beds distinctive of the North Horn for~ 

mation of the eastern part of the Wasatch Plateau. 

In earlier stages of the study, when this contact was 

supposed to mark the passage from Cretaceous to Eocene, and especially the considerable hiatus intervening 

'31 Scholl', S. L., Geology of tne Cedar Hills, Utah (unpublished notes). a2 Spieker, E. M., and Baker, A. A., Geology and coal resources of the 

Salina Canyon district, Utah: U. S. Geol. Survey Bull. 796, pp. 137-139, 

1928. ~ 

aa Spieker, E. M., The Wasatch Plateau coal field, Utah: p. S. Geol. 

Survey Bull. 819, pp. 81, 89-90, 1931. Through an error which es.cape.d notice in proofreading, the thickness of the Blackhawk formatiOn IS 

stated on pp. 27--28 of Spieker's report to range b~tween 700 and 1,oqo feet; the higher figure should be 1,500 feet. On Candland M.ountam 

(see pl. 31) the formation may be even more than 1,500 feet thick. 34 Spieker, E. M., and Reeside, J. B., Jr., Cretace6us ~nd Tertiary formations of the Wasatch Plateau, Utah : Geol. Soc. America Bull., vol. 36, 

p. 445, ,1925. . . 445 447 fi 3 llll Spieker, E. M., and Rees1de, J. B., Jr., op. cit., pp. - , g. . 
LATE MEqOZOIG AND EARLY CENOZOIC HISTORY OF CEN'l'RAL UTAR 131 

between the late Montana and theW asatch, it appeared 

to present a serious problem. However, now that the 

lower North Horn strata are known to be late Cretaceous, the lack of a clear-cut boundary not only involves 

no difficulty but is seen rather to indicate the normal 

unbroken progression from postorogenic gravels and 

sands to colored muds and fresh-water limestones, with 

less sand, and finer, as the plain of aggradation was built 

up and the highland source was worn down. The boundary as 1~ow drawn is purely lithologic and is placed at _ the hor1zon of greatest change between the sandstone 

and. conglomerate of the Price River and the variegated 

and other beds of the North Horn. In general it is not 

difficult to recogn~ze, and at places such as North Horn 

Mountain there is notable contrast between the sandstones of the Price River and those intercalated in the 

North Horn, which are much lighter in hue. In the 

western belt, however, where the Price River is very 

coarse-grained and overlaps the old foothill togography 

of the late Cretaceous mountains, there are localities 

where itis difficult to distinguish from the North Horn ~r~a. · 

The contact between the Price River and North Horn 

formations is not at the same horizon throughout the 

region. In places, such as Joe's Valley, it can be seen 

in general view to rise in the section. In any given 

section this change records the shifting, at that place, 

of the margin between the lateral belt of coarse mate-- rials on the west and the belt of finer materials on the 

east. This margin, or zone of transition, between the 

two belts migrated westward, in the main, as the source 

ar~a was worn down, and-in consequence the boundary 

between the two formations doubtless migrates stratigraphically upward toward the west. Farther east it 

may be more stable or may even rise. 

AGE 

The age of the Price River formation is definitely 

fixed, at least for the lower part, as Montana, and it 

probably is late Montana. Fossils already listed from 

the Castlegate sandstone member 36 place it as probably 

equivalent to the Fruitland and Kirtland formations 

of the San Juan region and other late Montana formations of the Colorado Plateau and adjacent mountains.37 

Furthermore, the Castlegate, il). its eastward extension 

along the Book Cliffs, changes gradually to a huge tongue of littoral marine sandstone penetrating marine 

shale, the upper parts of which contain an abundant 

Montana fauna that .is probably not so late in age .as 

the Fox Hills.38 The North Horn formation probably 

is Lance in age, and fhe ,upper part of the Price River 

may also be, but no fossils have yet been found in those 

beds. The passage from late Montana to Lance probably lies somewhere in the upper member of the Price 

River formation or perhaps in the lower few hundred 

feet of the North Horn formation. 

REGIONAL• RELATIONS AND CORRELATION WESTWARD 

From the type locality, in the Castlegate district, the 

Price River formation has been traced southward and 

westward to the Salina Canyon district, thence northward to the Thistle district, and eastward across the 

northern part of the plateau to the type area. Outcrops 

are practically continuous across the region, excepting 

the west flank of the plateau, and there is little doubt 

of continuity throughout. In most of the plateau the 

Castlegate sandstone member is recognizable and the 

formation is fairly uniform in character and stratigraphic relations. In the northwestern part, however, 

the outcrops on the western border are separated from 

those in the central belt by a strip of the crest in which 

the formation is covered by later beds for minimum distances of from 4 to ·6 miles and cannot be traced through 

anywhere. The general stratigraphic relations agree 

so 'well, however, that the correlation is made without 

reservation, especially-in consideration of the remarkable uniformity of stratigraphic relations in the large 

areas through which the beds have been traced without 

interruption. The possibility of deceptive lateral 

change in the concealed areas is set aside by the fact 

that the one important lithologic change, from the twofold sandstone formation of the type section to the 

single massive conglomerate of the west (described below), is fortunately revealed by continuous areas of 

outcrop in the central belt near Bennion Creek. (See 

fig. 14, loc. 3.) The evidence bearing on this correlation 

is here stressed because of its importance in the conclusions that arise from the correlation of the eastern Price 

River with the big conglomerate of the west, with respect to the date of the fo~ding in the Wasatch Mountains. In order to make the case absolutely clear, it'is 

well to review certain features of the areal relations in 

some detail. 

From Castiegate westward the Price River rocks may 

be traced . without interruption into the hills east of 

Pleasant Valley and northeast of Scofield. Between 

the upper course of Beaver Creek, however, and the 

canyon of Price River, in the western half ofT. 12 S., 

R. 8 E., Salt Lake meridian,39 theTe is a divide across 

which the Castlegate sandstone member cannot be 

traced. On Jump Creek not far west of Beaver Creek 

the Casilegate seems to disappear westward, as it does 

also on the south side of the canyon of Price River mentioned above. The sandstone identified as Castlegate 

on the north side pf Price River may be traced northwestwaTd .into the unit of undifferentiable sandstones 

and conglomerates which, thickening and becoming 

coarser, is the massive postorogenic conglomerate of 

the Thistle-Indianola district. In the northern part of 

the Pleasant Valley district the Blackhawk formation . is much thicker th~n it is not far across the divide to the · east. These facts might be interpreted to mean that 

the Castlegate changes westwaTd to finer-grained sediments in the · Jump Creek area and becomes there the 

upper part of the unit mapped as Blackhawk. Under 

this construction the sandstone on Price River, mentioned above as equivalent to the basal postoTogenic 

rocks to the west identical in appearance with the Castlegate, would neyertheless be higher in the section, 

above the Price River formation. The writer turned 

to this interpretation when the presumed Castlegate 

of the west was shown to be equivalent to. the postorogenic conglomerate and the folding was thought to be 

of age later than Montana, but it is an unnatural inter- · pretation, and was readily abandoned with the theory 

of post-Montana age for the folding. (See discussion 

of Sixmile Canyon formation.) Especially is this true 

in consideration of the widespread unity in the appear~ 

ss Spieker, E. M., and Reeside, J. B.; Jr., op. cit., p, 446. at For a summary of the regional correlation see the statement hy Reeside in Gregory, H. E., and Moore, R. C., op. cit. (Prof. Paper164), 

p. 113, fig. 6 (except the Manti area, for which the unit indicated as late 

Montana is the Sixmile I Canyon sa. udstone of this paper, now placed in 

the Colorado). , · as Fisher, D. J., The Book Cliffs coal field in Emery and Grand Counties, Utah: U. S. Geol. Survey Bull. 852, pp. 14-15, 1936. 31) Spieker, E. __ )\1., op. cit. (Bull. 819), pl. 31. 
132 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1 9 4 3-4 5 

ance of the Castlegate sandstone in the western part 

of the pla~au and its general similarity to that of the 

east. The western Castlegate is separated from outcrops of well-authenticated Castlegate in the central 

part of the plateau by only a fe~ small areas of forested 

country and fault zones, across which correlation now 

seems thoroughly valid. 

To sum up, although there are gaps in the areal distribution of the basal Price River rocks that prevent absolute demonstration of continuity and might possibly 

conceal an alternative relationship, the bulk of evidence 

in favor of continuity is so overwhelming that no other 

conclusion seems reasonable. The writer correlates the 

type Price River formation with the postorogenic conglomerate of the western districts, and the disconformIty at the base of the Castlegate sandstone with the 

angular unconformity of the folded belt, thus placing 

the main Laramide orogeny of central Utah between 

Blackhawk and Castlegate, or, approximately, middle 

and late Montana times. 

REPRESENTATIVE SECTIONS 

Desc,riptions of the formation in the type area and 

other eastern parts of the Wasatch Plateau have already been published,40 and are abstracted above sufficiently for present purposes. For the Salina Canyon 

district, on the southern margin of the plateau where 

the formation is characteristic and widespread, descriptions also have been published.41 In the northwestern 

part of the plateau, between Indianola and Thistle, the 

thick conglomerate facies discussed above is present. 

Here the formation ranges between 1,000 and 2,000 

. feet in thickness and consists largely of conglomerate 

which, at its coarsest, contains boulders of quartzite 

more than 2 feet in diameter. The conglomerate 

ranges in color from deep red, as in the striking canyon 

exposures of Red Narrows, east of Thistle, to dull gray, 

according to the amount of red silt present. The 

change from red to gray is loc.ally abrupt, as, for example, near Thistle at the mouth of Red Narrows. 

The conglomerate becomes finer eastward, but it extends as far east as the Pleasant Valley district) where 

it begins to change definitely to the conglomeratic sandstone facies of the east. A section taken on Bennion 

Creek is here presented as representative of the unit 

in the district of transition. This section is not complete and is thus not a record of the thickness of the 

formation, but it portrays the character of the rocks in 

the central-northern part of the plateau better than 

other available sections. 

Section of part of Price River formation on Bennion Greek, sec. 

· 11, T. 11 S., R. 6 E., Salt Lake meridian 

North Horn formation: 

Brown, buff, and gray sandstone, gray to red shale, 

and limestone conglomerate. 

Price River formation: 

1. Grit, conglomerate, cross-bedded, weathers Feet 

creamy bulf_________________________________ 25 

2. Grit, much like unit 1 but weathers brown________ 5 3. Grit like unit !________________________________ 66 

4. Grit like unit 1, gray with layers of green-gray 

silty sandstone------------- --------------- 8 

5. Sandstone, medium to coarse, creamy gray, con- taining scattered pebbles up to 1h inch_________ 3 . 6. Conglomer!lte, pebbles up to 1 inch in matrix of 

gray gr1L----------------------------------- 6 

7. Sandstone, gray, medium to fine, ir·regularly cross- bedded, containing locally some gray grit and coarse sandstone, forms massive cliffs and ledge~, weathers buff in upper part____________ 248 

8. Conglomerate, gray where fresh, brownish gray to Feet 

dove gray in distant view ; pebbles and boulders 

up to 1 foot common, occasional larger boulders, 

well-rounded quartzite and quartzitic sandstone. (some containing Fusulina), in rna trix of fine 

to medium light-gray sandstone; massive, forming strong cliffs : 110 feet measured at exact lo- cality of section, 'base not certain anywhere, but 

maximum thickness here' probably------------- 200 

/ Total_______________________________________ 561 

FOSSILS 

The Price River rocks are largely unfossiliferous. 

Finer sediments intercalated with the dominant coarse 

sandstones and conglomerates of central Utah have 

yielded a few fossils in the W ~satch Plateau, which. have been identified by J. B. Rees1de, Jr., as follows: 

Un~o priscus Meek and Hay~en. 

Umo cf. U. danae Meek and Hayden. 

Sphaerium p~anum Meek and Hayden. 

Modiola regularis Whitfield. Viviparu,s panguitchensis White. . Viviparus cf. V. leidyi Meek and Hayden. 

Vi viparus cf. V. leai Meek and Hayden. 

Goniobasis? subtortuosa Meek and Hayden. 

Goniobasis cf. G. judithensis Stanton. 

Pwnorbisf sp. 

These fossils are considered by Reeside to be characteristic of the late Montana stage in the Upper 

Cretaceous of the Cordilleran region, an age determination which agrees with the better-established conclusion 

for the Book Cliffs, where the Castlegate member forms 

part of a fossiliferous marine section that is clearly of 

late Montana age. .... . · 

The conglomerates of the western belt have yielded 

no fossils, but a sandstone bed above the main conglomerate of the Price River in the Gunnison Plateau near vV ales, Utah, has been found to contain the following 

species, identified by Reeside : ---... .-

Goniobasis tenuicarinatus Meek and Hayden. 

Goniobasis aff. G. nebrascensis Meek and Hayden. 

Vitrina aff. V.? obliqua Meek and Hayden. 

Viviparus nanus White. 

Paysa pleuronwtis White. 

Sphaerium sp. 

Bulirius sp. ~ 

These fossils are of interest in that they come fron1 

the locality where C. A. White collected a number of 

species that he assigned to the Wasatch forn1ation, and 

they are cited here principally on that account. The 

significance of this occurrence is discussed below, in the 

paragraphs on the North Horn fossils. (See p. 134.) 

The fossil-bearing beds near Wales may be somewhat 

younger than the main body of the Price River formation to the east, but as far as the regional stratigraphy 

is now known they should be Cretaceous. 

CRETACEOUS AND TE.RTIARY SYSTEMS 

NORTH HORN FORMATION 

DEFINITION AND LITHOLOGIC CHARACTER 

The lower member of the Wasatch formation as heretofore identified in the Wasatch Plateau 42 is here redefined as the North Horn formation. The name is 

derived from the type locality, on North Horn Mountain 

4o Spieker, E. M., and Reeside, J. B., Jr., op. cit. (1925), pp. 445-448. 

Spieker, E. M., op. cit. (Bull. 819), pp. 39-45. ' 41 Spieker, E. M., and Baker, A. A., op. cit. (Bull. 796), pp, 135, 

139-143. 4~ Spieker, E. M., and Reeside, J. B., Jr., op. cit. (1925), p. 448. Spieker, 

E. M., op. cit. (Bull. 819), pp. 45-48. ' 
LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL UTAH 133 

(loc. 4 on fig. 14) in Ts. 18 and 19 S., R. 6 E., Salt Lake 

meridian. In the western part/ of the plateau the 

formation consists of the former lower Wasatch exclusive of the basal conglomerate, which is now placed in 

the Price River formation. The North Horn includes 

an assortment of the lithologic types hitherto considered 

regionally characteristic of the Tertiary-variegated 

shale and sandstone, conglomerate, freshwater limestone, 

and other beds-which at the type locality is clearly 

divisible into four gross units as shown in the following 

section. · 

Generalized section of North Horn formation at type localitly on 

southwest point of North Horn Mountain · 

Flagstaff limestone (forms top of mountain). 

North Horn formation: Feet 

1. Shale, red and variegated in upper part, gray in 

lower part, with interbedded buff and gray sandstone and some limestone, the bedding very even · and individual layers thin ; lacustrine in origin; 

forms steep slopes and cut banks beneath limestone cliffs or Flagstaff_________________________ 250 

2. Shale, gray to variegated, with thin beds of buff 

sandstone, in general irregularly bedded; floodplain deposits; forms gentle .slopes______________ 300 

3. Shale, gray to black; sandstone, buff to light cream and gray, chiefly fine; some limestone, in very 

evenly bedded succession, layers generally not over 5 feet thick ; mainly lacustrine ; generally 

capped by resistant sandstone and forming shoulqer or terrace with steep front slope____________ 250 

4. Shale, gray in lower part, variegated in upper; 

sandstone, buff to gray, mainly medium to fine but 

with conglomerate in places; minor amounts of 

limestone ; dominantly flood plain in origin ; 

forms gentler slopes between unit 3 and Price 

River formation______________________________ 850 

Sandstone of Price River formation (exposed above Castlegate sandstone member on Rock Canyon Creek). 

TheN o~;~a~:;:~o=:~i~~-i~-~j,i~-~~~-~f-~j,~~~~at~~ thus represents an alternation between fluviatile land 

lacustrine conditions. Units 1 and 3 bear the distin- guishing characteristics of lake deposits; units 2 artd 4 

show dominantly the irregular bedding, nonpersistence 

of layers, and variety of physical constitution that are 

typical of flood.;plain and channel deposits. As they 

appear at the type locality, these units may be recognized on plate 22. 

REGIONAL CHARACTERISTICS 

In the central part of the plateau the four units distinguished in the section on North Horn Mountain are 

9000 w. 

I 8000 

7000 

6000 

SANPETE 

VALLEY 

regularly present and -easily traceable in an area of 

about 600 square: .miles, the center of which is east of ~Ianti. In all dirkctions away from this area the fourfold division gradually disappears, other large-scale 

divisions locally t.aking its place, but the whole formation becomes generally more unified. This regional 

unity is of significance in the matter _of age relations, as 

is brought out in succeeding paragraphs. The formation thickens to the north and east, attaining 2,200 to 

2,500 feet between Castlegate and Soldier Summit, and 

generally thins westward, a minimum of about 590 

teet having been observed on Salina Creek.43 In the 

eastern part of the plateau it contains freshwater limestones and other lacustrine beds irregularly scattered 

throughout, and im places it is impossible to define a contact. with the Flagstaff. A few thin beds of poor coal 

are also present here. In general, the North Horn 

strata constitute a record of rapidly shifting flood-plain 

and lacustrine conditions. 

A few salient :Eacts respecting the distribution of the 

formation east of the Wasatch Plateau are given on 

page 140. 

RELATipNS TO ADJACENT FORMATIONS 

The North Horn formation grades downward into the 

conglomerate or sandstone of the Price River formation, 

with no evidence of break, at all places where the two 

formations are known. It passes likewise transitionally 

upward into the Flagstaff limestone in most of central 

Utah. On the western margin of the plateau, however, 

all four units of the type section were tilted and truncated by erosion before the deposition of the Flagstaff, 

as shown in figure 17. The disturbance that produced 

this angular unconformity was apparently confined to 

a narrow zone now roughly coincident with Sanpete 

Valley, and -the only place where the angular contact 

between the Flagstaff and theN orth Horn can be proved 

to be depositional is the Sixmile locality, not far south , of Manti. Throughout the western piedmont of the 

plateau-\Yest of the eastern margin of this disturbance-the Flagstaff overlies all older rocks in angular 

contact, but everywhere, except at Sixmile Canyon and 

two other localities, the contact is a thrust fault of the type described by Billings 44 as strip thrusts. The 

thrusting is much easier to explain, however, if it is 

assumed to have taken place along a preexisting angular 

unconformity. At two widely separated localities, one 

48 Sp~eker,, E. M., and, Baker, A. A., op. cit. (1925), p. 144 (lower unit 

of section given). 1 , 

44 Billings, ~· P., Tl rusting younger ro1

cks over older: Am. Jour. Set, 

5th ser., vol. 2o, pp. 1.>3-155, 1933. 

WASATCH 

MONOCLINE 

E. 

5000~~~~~~~~--------------~--~~----------~------------~ Sanpete t Funk Valley Sixmile Canyon formation 

formation AI len formation . 

Valley 

shale 

FIGURE 17.-Cross sec_tion of j ocks exposed in Sixmile Canyon near Manti. 
134 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1 9 4 3-4 5 

in Salina Canyon 3 to 5 miles east of Salina (see pl. 

25; B) and the other 2 miles east of Indianola; the basal 

Flagstaff overlies steeply folded J uras,Sic and Cretaceous 

rocks in angular unconformity that has not been deformed by thi·usting. The interpretation of this preFlagstaff unconformity is further considered in the discussiOn of the Flagstaff limestone. (See p. 136.) 

Thus, despite the regional appearance of transition 

in the passage from North Horn to Flagstaff east of 

the Wasatch monocline, in the western districts the two 

formations were unmistakably separated by a physical 

disturbance. The significance of this disturbance in 

the regional history is discussed in the part of this 

paper devoted to orogenic movements. (Seep. 155.) 

Whether or not the apparent transition between 

North Horn and Flagstaff signifies actual continuity 

of deposition during the epoch of disturbance and erosion on the west, it is worthy of note that no effects of 

the folding are visible at remarkably short distances to 

the east of the disturbed belt. In Sixmile Canyon, for 

example (see fig. 17), the angular unconformity may 

clearly be seen to pass eastward into a disconformity, 

all trace of which disappears within a mile up the canyon. In other canyons to the south, where the angular 

unconformity passes underground eastward, the rocks 

rising on the monocline to the east show transition a.t 

the base of the Flagstaff, within a few miles. These 

facts are plain; but it is difficult in face of them to picture the disposal of the coarse sediments that must 

have resulted from. the erosion of the upturned Cretaceous sandstones and conglomerates. As matters 

stand, the evidence must be accepted as showing that a 

pronounced disturbance may produce no directly observable effect in contemporaneous strata very near 

to the folded area. 

AGE AND CORRELATION 

-Evidence bearing on the age of the North Horn 

formation rests in two groups of fossils, one of freshwater mollusks and the other of vertebrates. The invertebrates so far collected are brought together in the 

following list. 

Fossils from North Horn formation, about 1,000 feet above base, 

on Wasatch Plateau east of Mount Pleasa-nt, Utah 

[Identified by J. B. Reeside, Jr.] 

Unio letsoni Whitfield. 

Union. sp. aff. U. letson'i and U. biesopoides Whitfield. 

Unio priscus Meek and Hayden. 

Unio cf. U. clinopisthus White. 

Unio cf. U. shoshonensis White. 

Bulinus cf. B. sub,elonuatus Meek and Hayden. 

Bulinus cf. B. atavus White. 

Bulinus longiusculus Meek and Hayden. 

Columna? teres Meek and Hayden. , Goniobasis aff. G. tenuicarinatus Meek and Hayden. 

Goniobasis tenuicarinatus Meek and Hayden. 

Viviparus trochiformis Meek and Hayden. 

Viviparus panguitchensis White. 

Viviparus nanus White. 

Viv-iparus cf. V. wyomingensis Meek. 

These are the fossils, mentioned on earlier pages, that 

first aroused suspicion as to the Wasatch strata of central Utah. Their significance was at first set aside as 

uncertain, largely because of the general reputation for 

long range sustained by freshwater faunas. The results of the present investigation, however, suggest that 

the values involved may be underestimated, and the 

writer feels that the freshwater mollusks of the stages 

here discussed deserve thoroughgoing, restrictive study 

on a precise stratigraphic basis. This opinion, several 

years in the making, was definitely fixed when Reeside 45 

brought to attention the fact that many species are on 

record as Wasatch because they were described in the 

pioneer days ·from strata then identified as Wasatch 

but now either uncertain in stratigraphic position or 

known not to be Wasatch. ·An outstanding example is 

the record of Wasatch species by C. A. White from 

Wales, Utah; 46 the beds there from which White collected are now known .to belong to the Price River, 

North Horn, and Flagstaff formations. In the wide 

territory over which the Wasatch formation has been ,mapped, comparatively few localities have yielded the 

diagnostic vertebrate faunas; all others should be held 

in doubt. 

Vertebrate remains have been found in two general 

zones of the North Horn formation, one in unit 4 of the 

section earlier given, from 140 to about 500 feet above 

the base, and an upper zone in unit 2. From the lower 

zone, collections were made in 1935 by J. B. Reeside, 

Jr., and the writer at 26 stations, of which 23 are on -the southwest ridge of North Horn :Mountain, in the 

type area of _ the formation, and the remaining three 

in Manti, Sixmile, and Twelvemile canyons on the west 

slope. The material has been identified by C. W. Gilmore as dinosaurian, chelonian, and crocodilian as fol- lm, s (summarized from aH localities) : 

Cera topsia : Frill fragments, horn cores, dentary bones, vertebral centra_, 

tooth, metapodial, terminal phalanx, caudal centrum, 

squamosal, parietal, skull, and other bone fragments. 

Theropoda: 

. Caudal vertebra, teeth. 

Hadrosauridae: 

Radius, ulna, metacarpals, phalangials of hind foot. Smaller 

than any other known Hadrosaurian. 

Chelonia: . J>Iates of Trionychid, and genera Basilemys, Baena. 

Crocodilia: 

Tooth, vertebral centrum. 

Nearly all these fossils represent groups distinctive 

of the Upper Cretaceous. Most informative are the 

Ceratopsia, concerning which Gilmore says: 

The Ceratopsians, judged from this collection, were the predominating animals of this area, as their remains are recognizable from 11 different collecting stations. One specimen, con- sisting of the right squamosal and so-called parietal, shows a frill development unlike any described form but sufficiently perfect to indicate its distinctness from those having fenestrated 

frills; and since the nonfenestrated forms are all confined to the 

Lance formation 01~ its equivalents, the inference is that the 

present specimen comes from a formation that is close to, if not 

equivalent to it in age. 

At the time when this vertebrate material was collected the question was considered whether the bones 

were indigenous to the strata in which they occur; the 

fragmental character of the fossils and their generally 

sparse occurrence suggested at first that they might have 

been derived from _older rocks, but the sum of evidence 

was interpreted 47 to mean that the bones were in their 

original place of burial. Material collected by C. W. 

Gilmore in 1937, including articulated parts of skeletons, notably one of a giant sauropod, removes all doubt 

on this question. · 

45 Reesi<le, J. B., Jr., personal communication. 46 White, C. A., On the relation of. the Laramie molluscan fauna to that of the succeeding freshwater Eocene and other groups: U. S. 

Geol. Survey Bull. 34, 1886. 47 Spieker, E. M., Orogenic history of central Utah : Science, new ser., vol. 83, 1936. 
/ 

LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL UTAH 135 

The dinosaurian remains come from the lower 500 

feet of the formation. The middle part has yielded 

no vertebrate fossils diagnostic of age, but the upper 

part contains mammalian bones unquestionably Paleocene in age. In 1935 a poorly preserved fragment of 

a small skull was found, which was characterized by 

C. L. Gazin and G. G. Simpson as generically unidentifiable but in their opinion not Cretaceous in age, and 

on the basis of this statement the writer made a tentative announcement 48 that the passage from Cretaceous 

to Tertiary lies within the North Horn formation. -Collections made in 1937 by C. W. Gilmore and studied 

by Gazin 49 confirm this conclusion. 

The North Horn formation thus embodies strata of 

latest Cretaceous and earliest Tertiary ages, probably 

to be correlated in some part with the Lance and Fort 

Union formations of the northern plains, and with the 

Ojo Alamo, Puerco, and Torrejon formations of the 

San Juan Basin, to mention the two regionsthat have 

afforded most complete fossil evidence in this part of 

the geologic column. It is of especial interest and significance that the passage from Cretaceous to Paleocene 

is recorded by an apparently transitional succession of 

strata. As pointed out in the foregoing description of 

the forn1ation, no physical basis for regional subdivision of the strata grouped in the North Horn formatiOn has been recognized, and in the present state of 

knowledge a boundary between Cretaceous and Paleocene cannot be mapped. The transition is apparently 

even more complete than in the areas of Montana and 

Wyoming, .where distinction between Lance and Fort 

Union has been the subject of much discussion. This 

phenomenon is of major importance in the CretaceousTertiary boundary question, which is discussed at some 

length farther on in this report. (See pp. 142-146.) 

USE OF TERM PALEOCENE 

The term Paleocene, introduced on paleobotanical 

grounds by Schimper 50 in 187 4, has been widely used in 

Europe to designate the lowermost division of the Tertiary, an epoch of standing equal to that of the Eocene, 

Oligocene, Miocene, and Pliocene. ·In North America 

this division was not generally recognized until the 

vertebrate paJeontologists began to recognize notable 

differences between the mammaUan faunas of the lowermost Tertiary (Fort Union, Puerco, Torrejon, and Tiffany) and those of the overlying Eocene (Wasatch). 

These differences seemed to warrant the separation of 

the basal strata from the remainder of the Eocene, and 

among the vertebrate paleontologists acceptance of the 

Paleocene as a standard division of the Tertiary has 

come to be unjversal. 51 Other American geologists, 

how: ever, have been slower to adopt the term, but have 

generally preferred to include the strata concerned in 

the Eocene, commonly using for them the designation 

basal Eocene, in distinction from the lower Eocene, to 

which the Wasatch strata have long been assigned. The 

United States Geological Survey followed this procedure until June 12, 1939, when the name Paleocene 

was officially approved. 

The Paleocene, as thus recognized by the. Geological 

Survey, comprises the time during which the Fort 

Union and equivalent strata of the Cordilleran Interior 

were deposited. It is a series and epoch term, on parity 

with Eocene and the other recognized divisions of the 

Tertiary. 

The Paleocene of most European geologists, however, 

follows the original definition of Schimper, which includes more than the interval specified above. The Fort" 

Union formation of the northern plains and beds containing the Puerco, Torrejon, and Tiffany faunas of the 

San Juan Basin are equivalent to the strata ofthe Montian and Thanetian stages of the standard European 

column. The Europea1i Paleoc~ne includes, in addition 

to these two stages, the Sparnacian, which is the equivalent of the North American vV asatch. Without entering upon a discussion of the basis on which the European partition re~ts, it may simply be observed that for 

North America the most effective division separates the 

Fort Union and the Wasatch. Not only are the faunas 

of these two units distinct, but the vV asatch faun~t 

marks the beginning of a unified succession that continues upward through the Eocene . . If the Paleocene 

is to be recognized by Atnerican geologists; its upper 

limit must be set at the top of the Fort Union. As to 

reconciliation with the European scale, it is obviously 

unfortunate that complete agreement cannot be attained, but the ad vantages to North American geologists of the classification here given outweigh the disadvantages involved in making allowances for differences in 'international usage. Further, 'vhen it is recognized that the North American section, comprising 

in its best development thousands of feet of strata and 

a rich succession of mammalian faunas, is probably the 

fullest record of early Tertiary time in the world, the 

possibility may be considered that a reasonable standard Paleocene for the whole world might follow these 

lines. In other words, the reasons given in North 

America for excluding the Sparnacian equivalents from 

the Paleocene might outweigh those given in Europe 

for including thJ Sparnacian. 

TE.RTIARY ·SYSTEM 

FLAGSTAFFL~ESTONE 

DEFINITION, LI'f'HOGRAPHIC CHARACTER, AND EXTENT 

The name Flagstaff limestone is here applied to the 

strata hitherto described as the Flagstaff limestone 

member of theW asatch formation, 5

2 and no redefinition 

of stratigraphic limits is necessary. As long as the 

Flagstaff was considered to be a lacustrine phase between flood-plain deposits of Wasatch age, its inclusion in the Wasatch formation was consistent. Now, 

however, the former lower men1ber is known not to be 

of Wasatch age, and the Flagstaff is known to be more 

closely related to the Green River formation than to 

the strata formerly classified as Wasatch. As pointed 

out below, it contains fossils that suggest an age older 

than Wasatch. In thickness and extent it is one of the 

major stratigraphic units of the region, and in view of 

these facts it is elevated to formational rank. 

The Flagstaff limestone is present throughout the 

Wasatch Plateau and extends in all directions for unknown distances, except eastward, where, although it 

has been eroded from the vast 'basin of the Colorado 

48 Spieker, E. M., Late Cretaceous-early Eocene history of central 

Utah; Geol. Soc. America Proc. 1935, p. 374 (abstract), 1936. 49 Gazin, C. L., A Paleocene mammalian · fauna from central Utah : Washington Acad. Sci. Jour., vol. 28, No. 6, pp. 271-277, 1938. 5° For a definitive statement see Wilmarth, M. G., The geologic time 

classification of tii.e United States Geological Survey compared with 

other classifications: U. S. Geol. Survey Bull. 769, pp. 54-56; 1925. 51 Simpson, G. G .. 'l'he Fort Union of the Crazy Mountain field, Mont., 

and its mammalian fauna; U. S. Nat. Mus. Bull. 169, pp. 16, 21, 1937. 

Scott, ,V. B., A history of land mammals in the western hemisphere, 2d ed .. pp. 99-100, 230- 232, Macmillan, 1937. 52 Spieker, E. :M:., and Reeside, J.'- B., Jr., op. cit. (1925), pp. 448-44U. SpiP-ker, E. l\1., op. cit. (Bull. 819), p. 46. 
/ 

136 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

River, its extent-in the plateaus north of the Book Cliffs . is roughly known. It consists domjnantly of freshwater limestone of many kinds, with interbedded gray 

shale and minor amounts of sandstone, gypsum, oil 

shale, and volcanic ash. Toward the west it contains 

coal, locally, and southwestward much of the limestone 

is silicified. It lacks generally the red and var-iegated 

beds that characterize the adjacent formations and is 

easily distinguished in general view by its extensive 

white or cream-colored outcrops, which form a striking 

and almost unique scenic feature of the higher tabular 

masses in the Wasatch Plateau. (See pl. 22.) Its 

lithologic character is too varied for more than summary mention in this paper. 

In the vV asatch Plateau the Flagstaff limestone 

ranges between 200 and 1,500 feet in thickness, with an 

average between 800 and 1,000 feet; it is generally 

thicker westward and southwestward. In the southern 

part of the plateau proper, where it is Inore than 1,000 

feet thick and almost exclusively fresh-water limestone, it is an imposing body of rock, forming high cliffs and 

parapets on the crest of the plateau, which dominate 

the landscape and are visible from the bordering valleys 

for many miles. 

REGIONAL RELATIONS 

Between Soldier Summit and Thistle the red beds and 

sundstoi1es formerly designated the upper member of 

the Wasatch formation (the Colton formation of this 

report) change westward, by gradation and intertonguing, to white and gray shale, sandstone, and limestone of 

the Green River, so that in the Thistle district there 

are no strata of the variegated type immediately overlying the Flagstaff. Here the Green River type of 

lithology really begins at the base of the Flagstaff. 

Similar relations are observable south of the line of 

this section; for example, in the Gunnison Plateau and 

in parts of the western border belt of the· Wasatch Plateau, the Colton strata are absent or are seen to change 

laterally into Green River beds. In general, the Flagstaff has the actual form of a tongue of Green River 

strata extending southward and eastward from the 

Thistle district for radial distances well over 75 miles. 

Despite this clear-cut relationship, the Flagstaff is 

not formally designated a tongue of the Green River 

formation. Its thickness and extent bespeak formational rather than subsidiary rank; although in general 

of the Green River type, it differs sufficiently in dominance of limestone to be separated; and it is older, perhaps considerably older, than the typical Green River. 

The facts that bear on its position in regional nomenclature suggest separation from the Green River as an individual unit. 

However, apart from the interests of nomenclature, 

the fact remains that the Flagstaff of the western dis- trict~ ~epresents the initiation of widespread lacustrine 

conditiOns that apparently continued uninterrupted 

through the deposition of the Green River formation 

the dominant type of sediment changing upward fro~ limestone to shale: This is of interest in that it ·shows 

an extension, in area as well as in time, of the Uinta 

Lake of Bradley,53 in which these sediments were 

deposited. . 

The Flagstaff limestone has been traced to the south-

: ern limits of the Wasatch Plateau, roughly 100 miles 

from the western end of the -Uinta Basin. The thickest 

known sections are in the southern part of the Wasatch 

Plateau. Its exterit farther south is not exactly known; 

it appears to be absent in the high plateaus immediately 

south of the Wasatch Plateau, but it may have been 

removed by erosion. In the extreme southern districts 

of the High Plateaus the beds assigned to the Wasatch 

formation contain thick units of limestone whose similarity to the Flagstaff, in stratigraphic position as weil 

as in lithology, is evident fTom available descriptions 54 

and has been verified in part by the writer's observations. If these southern beds are Flagstaff, the northsouth extent of the £ ..ormation is at .least doubled, and 

the area of Uinta Lake is accordingly increased. In 

the writer's opinion the southern limestones are more 

likely Flagstaff than not. · 

AGE AND CORRELATION 

Some of the limestone beds in the Flagstaff are 

charged with fresh-water gastropods and pelecypods. 

It is important to note that the Flagstaff of theW asatch 

Plateau contains certain of the very species that at first 

caused doubt as to the Wasatch age of the North Horn 

strata (for example, Unio prisCU8, Viviparus pangwitohensis, V. leai), and that some of the fossils described 

by C. A. White from Wales, Utah (see p.134), may have 

come from the Flagstaff. Despite the uncertainty of 

this evidence, the writer is inclined toward the same 

interpretation as that which eventually was demonstrated to be valid for the N oTth Horn invertebrates 

namely, to consider the Flagstaff limestone as probably 

Paleocene in age. The relations between the Flagstaff 

and the upper part of the North Horn, which probably 

belongs in the middle part of the Paleocene and not the up~r, tend to favor this hypothesis; the Flagstaff proba:bly follow~d the ~orth Horn with n<? great. lapse of 

time, and might easily have been deposited in the later 

part of the Paleocene. As matters stand, the age of the 

Flagstaff, frankly to be r egarded as uncertain, seem~ 

more likely to be Paleocene than lower Eocene. 

PRE-FLAGSTAFF UNCONFORMITY 

The regionally dominant ti·ansition between the 

Flagstaff limestone and the underlying North Horn 

formation, and the angular break between the two in 

Sjxmile Canyon ~ are described in the foregoing section 

on the North Horn formation. There should be added 

here, however, some discussion of the angular uncon- form~ty in the western districts where the Flagstaff 

overhes all the older rocks of the region. This unconformity is interpreted in the present study as the result 

of the same movement as that which produced the. angular relations between the Flagstaff· and the North Horn 

in Sixmile Canyon. Inasmuch as Sixmile Canyon is 

the only locality at which the North Horn strata have 

been found beneath the unconformity, and further in ,view of the difficulty there of ascertaining the true 

relations, question may arise respecting the extent of 

the orogenic movement postulated, if not as to its actual 

validity. 

The pre-Flagstaff unconformity is widely present in 

the western border belt of the Wasatch Plateau and adjacent valleys between Salina and Manti. It is also present in a hogback not far east of Indianola, where .the 

Flagstaff overlies vertical Arapien shale only a few miles 

from abundant exposures in which the full normal sec3 Bradley, W; H., Varves and climate of the Green River epoch: U. S. Geol. Survey Prof. Paper 158, p. 88, 1930. 54 Gregory, H. E., and Moore, R. C., The Kaiparowits region: U. S. 

GP.ol. ·Survey Prof. Paper 164, pp. 114-116, 1931. 
LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL UTAH 137 

tion is present. The poss_ibiljty to be considered is tJ:at 

these unconformable contacts resulted, not from erosiOn 

and burial of rocks folded in the post-North Horn disturbance but from the presence of ar~as that remained 

high a:ft~r the early Laramide folding and that were · first submerged by the Flagstaff lake. Such areas. are 

known along the east front of the Wesatch Mountains; 

Eardley,55 Schoff,56 and.Baker57 h::tVe observed that the 

entire post-early Laramide successiOn overlaps the steep 

front of the ancient mountains, with the Flagstaff r:esting in places on folded Paleozoic and Mesozoic rocks. 

At these localities the rocks that appear toward the east 

between the Flagstaff and the folded mass, generally 

North Horn strata, show no evidence of pre-Flagstaff 

disturbance.58 Relations similar to these, in the same 

general belt, are described elsewhere in this paper. 

(~ee pl. 24, A.) · 

It is possible that the unconformity in the Sa1inaManti and Indianola districts is of the same sort. The 

writer prefers, however, the interpretation that it resulted from post-North Horn erosion,. for the fol~owing 

reasons. First the pre-Flagstaff eroswn surface Is very 

extensive in th~ Manti-Salina district, and it is remarkably even (see pl. 25, B); in these respects it is qui~e 

different from the occurrences on the old mountain 

front cited above. Second, it is many miles from the old 

mountain front-at least 25 miles in the latitude of 

Sixmile Canyon-assuming the front to have been at 

the site of the present Canyon Range. That so extensive a surface should have remained positive so far from 

the mountains and for so long a time-fr:om late mid~le 

Montana to middle Paleocene, approximately-while 

areas much nearer to the mountains were receiving notable thicknesses of Price Riv~ and North Horn sedi- · ments, seems less probable than the alterna;tive Ifere 

suggested. Third, c~mglomerate of the ~rice . River 

formation was deposited on the older eroswn surface 

in the Sixmile district, and there this surface is definitely truncated by the later one, as shown on figure 17. In 

weighing the fact that this locality is the only one that 

shows angular relations between the North Horn and 

the Flagstaff it must be recognized that in the folded 

belt the only other canyon that cuts through the angular 

unconformity is Salina Canyon. In that canyon the 

unconformity passes beneath· creek level before the 

critical part of the section appears; the highest folded 

rocks beneath it are sandstones of the Funk Valley 

formation. In other words, the Nqrth Horn-Flagstaff 

contact is buried in the part of the canyon where it 

might show an angular break. 

Another line of evidence that suggests extensive· rather than localized activity in the pre-Flagstaff disturbance is purely structural in nature. When the fold 

produced in the latitude of Sixmile Canyon is restored 

to its original condition, it turns out to have been a 

monocline of the type classic in the Colorado Plateaus 

to th'e southeast. The nature of the structure and its 

place in the· regional scheme are discussed farther on, 

in the summary of orogenic history. Structures of this 

order are generally extensive along _ the strike, not 

localized. A minor upwarp restricted to the vicinity ~f 

Sixmile Canyon-is of course possible, but the sum of evidence seems to favor a larger structure. 

These considerations lead the writer to think that 

the disturbance between North Horn and Flagstaff 

time penetrated a considerable part of the border area 

of the Wasatch Plateau. 

668015-46--4 

W .ASATCH PROBLEM 

The general pro lem of identifying~ the '\Y asatcf1 formation in central and eastern Utah IS outhned In the 

first part of this paper, and the changes in ·nomenclature now required for part of the fo'rmer Wasatch are 

set forth in the foregoing discussions of the North Horn 

and Flagstaff formations. Now that the former lower 

member of the Wasatch is known not to be Wasatch 

in age and serious doubt is cast on the Wasatch age 

of the 'Flagstaff, the question arises, how muc.h of the 

remaining section I may still properly by assigned ~o 

the Wasatch formation? · The attempt to deal with this · question leads at once into a larger problem, involvi~g 

the stratigraphic significance of the name Wasatch In 

the entire Cordilleran region. '.From Montan~ to New 

Mexico the name has been apphed, on the basis of various criteria, to strata presumably of ~ower Eocene 

age. Modern ihvestig~t~ons by b~th stratigraphers and 

paleontologists are raising questiOns on all Impor~ant 

aspects of this usage, and the many problems entaile.d 

are by no means easy to resolve. The full range of this 

subject is beyond the scope of the rr~se~t report;, however, much of the stratigraphic reVISIOn In_:volved In the 

conclusions here presented has resulted In some way 

from a study initially concentra:ted on the ~ asatch 

problem, and it seems wort~ w~Ile to -summari~e the 

major elements of the. ques.twn, If only to explain the 

nomenclature adopted In this ·report. 

The name W asatyh, one of the oldest surviyors among 

terms used by pioneers in western· American. stratigraphy was proposed in 1869 by Hayden 59 to Include 

the str~ ta exposed along the Union Pacific Railroad 

between Carter Station, Wyo., and Echo Canyon, U~ah. 

This obviously generalized defiJ?-ition covered a ~airly 

wide stratigraphic range, yet. It served as basis for 

Veatch 60 to outline more precisely the strata that he 

included in his Wasatch group, separated into.the Almy, 

Fowkes, and Knight formations, in ascend~ng order. 

Not long after Hayden's work Cop~ 61 described from 

the type area the fire representatives of the lower 

Eocene vertebrate fauna that later became famous as 

the 'Vasatch fauna and served as-basis for the establishment of a time ·stage in the early Tertiary. Areal 

geologists, following Hayden an~ Veatch, mal?ped tl~e 

Wasatch formation on lithologic and stratigraphic 

criteria over extensive areas. Vertebrate paleontologists found other occurrences of the sb-called Wasatch 

fauna, and it became widely known. ~he name :Wasatch 

gained prominence in usage an~ was Incl~ded In s~andard sections of the North American Tertiary published 

all over the world. 

This usage, however, has been far. from u~if?rm. 

That of the areal geologist has only sl~ghtly co~ncided 

with that of the vertebrate paleontologist; the diagnostic mammalian fauna has been found in only a few of 

the many areas where the Wasatch formation has been ___ · mapped. The usag~ of the paleontologi~t has adher:ed 

for the most part to a time stage approximately equ~valent to the Sparnacian of the European scale, and With 

55 Eardley, A. J., A limestone chiefly <!f algal. origin in th~ Wasatch 

conglomerate southern Wasatch M:ountams: M1ch. Acad. Sc1. Papers, 

vol 16, pp. 399-414, 1932. . ( bl' h d t ) 56 Schoff, s. L., Geology of the ceqar ~11ls, Utah unpu 1s e no es . 57 Baker, A. A., personal communlCa.twn. 58 See especially Eardlev, A. J., op. c1t., fig. 12, p. 401. . 59 Hayden, F. v., u. 81. Geol. Survey Terr., 3d Ann. Rept., p. 90, 1869; 

idem, 2d ed., p, 191, 1873. f t' f th estern eo Veatch, A. c., Geography and geology o a por wn o sou w w oming: U. S. Geol. Survey Prof. Paper 56, pp. 88-96, 1907. . f1 Cope, E. D., On the vertebrate foss1ls of the Wasatch strata, U. S. 

Geol. Geog. Survey Terr., 5th Ann. Rept., pp. 350-353, 1872. 
138 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1"943-45 

the progress ·of detailed study it has been refined by 

subdivision in which reference to the original Wasatch 

is not entirely satisfactory. Although the areal geologists have generally had in mind the lower Eocene 

time stage when they have identified the Wasatch 

formation, yet in places such as the area covered by this 

report and in western Colorado 62, strata mapped as 

Wasatch have been found to belong in older time divisions. One factor, which has contributed to the uncertainty of identification, is the stratigraphic confusion 

of freshwater mollusks already discussed in this paper. 

Although vertebrate remains have not been extensively 

found, invertebrate fossils have been widely collected 

and have been used to support the physicial identification of the Wasatch strata. 

An outstanding aspect of the regional stratigraphy 

that has played a part in the areal Identification of the 

Wasatch strata is the common occurrence in the part 

of the section assigned to the lower Eocene of variegated beds with varying amounts of coarse-grained 

sandstone and conglomerate (Wasatch) overlain by 

evenly bedded shale, limestone, and fine-grained sandstone (Green River). These two lithologic types intertongue, and the units are therefore partly equivalent 

in age from place to place. The fairly uniform appearance of this characteristic sequence in the highlands 

and structural basins of the Cordilleran region and the 

recognition of it as part of the standard Eocene 

sequence (Wasatch, Green River, Bridger, Uinta) have 

enco;uaged geologists to identify the variegated beds 

beneath the Green River as Wasatch. Further, and 

Inore important as regards the problem of nbmenclature 

here considered, it gave rise to the essential concept of 

Wasatch as composed of fluviatile sediments laid down 

on flood plains bordering and finally submerged by the 

lakes in which the contrastive Green River sediments 

were deposited. 

Out of these considerations arise several questions. 

What does the name Wasatch inean ~ Should it be retained, and if retained, how should it be applied~ 

Should it be restricted to (1) strata homogenetically 

equivalent to those of the type section; (2) strata of 

flood-plain environment as opposed to lacustrine, with 

or without regard to precise age relations; ( 3) strata 

definitely assignable to the · time stage presumably established by the vertebrate faunas; or ( 4) conceivably, 

to categories involving other combinations of these elements~ · 

In the stratigraphic sense usage should be established 

with reference to the type section, following the generally accepted rules of nomencla.ture.63 The type section, however, probably covers a stratigraphic range 

too extensive for practical purposes. Further, as subdivided by Veatch,64 the Wasatch group includes a 

strong angular unconformity between the Knight and 

older formations. Mansfield and Roundy concluded 65 

that this break might not exist, and after careful review of the evidence in the field the writer recognizes 

that there was ample reason for doubt, but it seems 

likely that the Almy formation, at least, underlies the 

Knight in angular unconformity. Traced regionally 

across southwestern Wyoming into northeastern Utah, th~ !{night formation is seen to overlap all the older 

folded rocks. Further, the section in Echo Canyon, 

part of the extensive original type area, embodies two 

angular unconformities-a lower one in the conglomerate series above Pulpit Rock, in addition to the break 

beneath the Knight, which is the o:rie noted by Lee.66 

The lower conglomerates, which have been generally 

classified as Wasatch, were placed in the Almy formation by Veatch.67 The stratigraphic identity of the 

Almy formation and its age constitute a problem that 

cannot be reviewed here, but it is the writer's opinion 

that the strata involved, especially the 'Conglomerates 

of Pulpit Rock, belong in stages elsewhere established 

as older than Wasatch. If the term Wasatch were to 

be used in strict adherence to the type section, it would 

probably have to be applied to units for which usage 

has long since . established names not only differ~nt, 

but also in part indicative of greater age than that customarily associated with the name Wasatch. In any 

6vent, until the actual content of the type section is 

carefully worked out, regional use of the term Wasatch 

in a strictly typical sense will be impossible. 

Added to these uncertainties in physical stratigraphy 

is the fact that the vertebrate paleontologists, whose 

usage has been more nearly standard than any other, 

have become dissatisfied with the term W asatch,'68 and 

some of them favor abandoning it.69 The name has 

been applied to faunas both older and younger than 

that of the Knight formation in the type area and has 

lost whatever typical sense it may once have had; it 

has become essentially a generalized term covering the 

whole lower Eocene. It is impossible to say how far 

the generalized sense dev_eloped by the paleontologists 

agrees with the sense that would prevail if the original 

stratigraphic definition were strictly followed. No vertebrate remains have been found in the Almy and 

Fowkes formations, and no fossils of any sort sufficiently diagnostic for definite age determination. 

Neither is it possible to surmise the extent to which 

agreement would obtain under the provisions of any 

restrictive revision such as those mentioned in query 

above. 

A logical conclusion from all this confusion and 

uncertainty would be to abandon the name 'Vasatch 

in favor of local terms more precise in significance. 

This is the conclusion reached by N ace 70 in a regional 

review of existing usage. There is some merit, however, in the attempt to retain the name. In view of its 

long history and its familiarity to geologists everywhere, it might still serve to designate fluviatile sediments of the age indicated by the vertebrate fossils of 

the type area; in fact, if it were desired to formulate a 

restrictive definition in terms of the type area, logical 

grounds exist for applying the name to the strata included by Veatch in the Knight formation. For many 

miles around Wasatch Station, Utah, from which Hay- -......den originally took the name, the strata exposed are 

typical Knight. Of course, Hayden made it clear 71 

that he intended to include in his Wasatch group "all 

the variegate.d beds which we have observed west of 

Carters station," and he specifically mentioned the mas62 Patterson, Bryan, A contribution to the osteology o'f Titanoides and 

.the relationships of the Amblypoda: Am. Philos. Soc. Proc., voL 73, pp. 

71-100, 1934. 63 Classification and nomenclature of rock units [joint committee re- port] : Geol. Soc. America Bull., vol. 44, pp. 430, 432, 435, 1933. 6! Veatch, A. C., op. cit., pp. 87-89. 6li Mansfield, G. R., Geography, geology, and mineral resources of part of southeastern Idaho: U. S. Geol. Survey Prof. Paper 152, p. 109, 1927. 66 Lee, \V. T., and others, Guidebook of the western United States, 

pt--B, The Overland Route: U. S. Geol. Survey Bull. 612, p. 85, 1915. 67 Veatch. A. C., op. cit., p. 89. 68 Scott, W. B., A history of land mammals in the western _hemisphere, 

2d ed., p. 100, 1913. . o9 Scott, \V. B., Jepsen, G. L., Gazin, C. L., personal communications. •o Nace, R. L., Summary of the late Cretaceous and early Tertiary stratigraphy of Wyoming: Wyoming Geol. Survey Bull. 26, 1936. n Hayden, F. V., Sun pictures of Rocky Mountain scenery, with a description of the geographical and geological features and some account of the resources of the Great West, pp. 106, 107, 111, 113-114, New York, 

1870. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 205 PLATE 18 

A. ARAPIEN SHALE AT THE TYPE LOCALITY IN ARAPIEN VALLEY. 

View wcsl across Arapien Valley south of Mayfield, showing characteristic blotched shale of Twelvemile Canyon member. 

B. ARAPIEN SHALE IN THE SALIN A DISTRICT. 

Gypsiferous shale of Twelvemile Canyon member about 5 miles northeast of Salina. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 205 PLATE 19 

A. UNDIFFERENTIATED · INDIANOLA IN THE GUNNISON PLATEAU. 

View southeast across Chicken Creek Canyon, southeast of Levan. Ledges of massive conglomerate are the dominant rock. 

B. FUNK VALLEY FORMATION. 

Steeply tilted sandstone and shale in the lower part of the formation on foothill ridge north of Funk Valley. Faulted capping of nearly horizontal Flagstaff strata faintly visible 

in middle distance; Sanpete Valley and town of Manti at upper left. 

INDIANOLA GROUP. 
GEQLOGICAL SURVEY PROFESSIONAL PAPER 205 PLATE 20 

A. SANDSTONES ABOVE THE CASTLEGATE SANDSTONE MEMBER OF THE P~ICE RIVER FORMATION IN WILLOW CREEK CANYON. 

The top of the Castlegate, at the locality shown in plate 20. B, i~ just visible to the right of the notch. The Wasatch Plateau is seen in the distance. 

B. CASTLEGATE SANDSTONE MEMBER OF THE PRICE RIVER FORMATION ABOUT A MILE ABOVE CASTLEGATE. 

A characteristic exposure of the Castlegate near the type locality. The entire unit, about 500 feet thick, makes the massive cliff. Above is the upper sandstone member of the Price River. 

SANDSTONES OF THE PRICE RIVER FORMATION NEAR CASTLEGATE 
GEOLOGICAL S URVEY PROF E SSIONAL P AP E R 205 PLATE 21 

A. CONGLOMERATE OF THE PRICE RIVER FORMATION IN RED NARROWS, EAST OF THISTLE. 

A representative display of the texture and outcrop of the lower part of the Price River in the western districts. The photograph was taken in 1924, and the ledge shown has since been completely removed in highway construction. 

B. PRICE RIVER AND INDIANOLA STRATA ON BJORK CREEK. 

Massive basal Price River, nearly vertical, on right; Indianola, dipping 60° into angular unconformity, on left. The exposed vertical surface of the Price River in center is the basal part of the formation. The Indianola strata are the uppermost of the section given in the text (p. 130). 

CONGLOMERATES Of THE PRICE RIVER FORMATION, WESTERN FACIES. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 205 PLATE 22 

A. FLAGSTAFF LIMESTONE ON CREST OF WASATCH PLATEAU. 

View northwest across the top of the south-central part of the plateau, at an altitude of about 10,500 feet. The flat divide here is held by a strong bed of silicified limestone, 

topmost Flagstaff; the base of the formation is some distance to the right, outside the field of view. The southern end of the Wasatch Mountains, about 50 miles distant, is visible on the skyline at the left. 

B. NORTH HORN FORMATION AT TYPE LOCALITY. 

Southwest spur of North Horn Mountain, looking north. The dinosaur-bearing zone (unit 4 of section given in text, p. 133) is exposed to left and in center (a); unit 3 (b) forms vegetated spur, unit 2 (c) bench and slopes above, and unit 1 (d) steep slopes beneath the Flagstaff limestone (e), which caps the mountain. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 205 PLATE 23 

A. COLTON AND NORTH HORN FORMATIONS IN GREEN RIVER CANYON. 

View northwest from a point below the mouth of Desolation Canyon. The dver is visible in the lower right corner. The units are numbered to correspond with the section given in the text (p. 140): 1, 2, 3, Colton formation; 4, North Horn formation; 5, Tuscher (?) formation. 

B. GREEN RIVER STRATA ON MINNIE MAUD CREEK. 

A characteristic view of the evenly bedded lacustrine· shales, marlstones, and other beds in the lower part of the Green River formation. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 205 ·PLATE 24 

A. NORTH HORN FORMATION Il\1 EAST FRONT OF WASATCH MOUNTAINS AT THISTLE. 

View southwest from bench above and north of Thistle. Rocks on left (a) are Jurassic, dipping steeply east in a hogback, part of foothills of late Cretaceous Wasatch Moun- tains. They are unconformably overlain by sediments of North Horn formation (b), nearly horizontal, filling ancient drainage channel on right. The conglomerate of the 

Price River formation may be present, covered, in lower part of present hollow. Crest of Wasatch Mountains forms right skyline. 

B. PRICE RIVER-INDIANOLA CONTACT NEAR WALES. 

View south across gap in east front of Gunnison Plateau west of Wales. Vertical beds of Price River on right. Indianola, overturned, dipping about 35°, on left. 

UNCONFORMITIES BENEATH PRICE RIVER AND NORTH HORN FORMATIONS. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 205 PLATE 25 

A. FLAGSTAFF-NORTH HORN UNCONFORMITY IN SIXMILE DISTRICT. 

View north acro~s gulch jU:st south of Sixmile Canyon. The Flagstaff (a) is at the sky line, dipping about 40° NW. and truncating the nearly horizontal beds of the underlying North Horn formation (b). The Price River formation (c) is visible in the bottom of the gulch. The lower angular unconformity over the Sixmile Canyon sandstone is out of sight to the left. 

B. ANGULAR UNCONFORMITY IN SALINA CANYON. 

View north across the canyon about 5 miles east of Salina. The upper rocks are all shales and limestones of the Flagstaff; the dark horizontal bed (a) near the mildde is red calcareous siltstone, basal Flagstaff. Beneath it are sandstone and shale of the Sanpete (h) and Allen Valley (c) formations, dipping about 30° E. 

UNCONFORMITY BENEATH FLAGSTAFF LIMESTONE. 
LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL UTAH 139 

sive congloillerates of Echo Canyon. It is probable, 

however, that he was not aware of the heterogeneity in 

the assemblage thus defined, and especially of the lack 

of unity between the low~r conglomerates and the strata 

at Wasatch station. In any event it is not the purpose 

nf the present discussion to reach a conclusion in the 

matter, but rather to state certain elements of the general 

problem. In the opinion of the writer the name Wasatch should not be abandoned without more thorough 

study of the type area than has yet been prosecuted. 

Nevertheless, to turn to the question immediately in 

hand for central Utah, with the general status of the 

name in such uncertain condition it seems hardly wise 

to attempt to identify Wasatch strata in the Wasatch · 

Plateau and surrounding areas. The former- upper 

member of the Wasatch formation in this region, therefore, is given a new name, the Colton formation, as defined below. The term "Wasatch age,'' as used in this 

report, means the general lower Eocene time division 

approximately equivalent to the ,Bparnacian of the 

European scale. 

COLTON FORMATION 

DEFINITIO~, GENERAL CHARACTER, AND RELATIONSHIPS 

The strata formerly classified as the upper member 

of theW asatch formation are here designated the Colton 

formation. The formation as thus defined consists of 

the beds in the hills north of Colton between the Flagstaff limestone and the Green River formation. These ·· are gray, pepper-and -salt sandstone, greenish-buff sandstone, and siltstone that commonly weathers golden 

brown, and shale ranging :from deep red to variegated 

and gray in color. Above Kyune, 2 miles east of Colton 

at the head of Price Canyon, the formation is almost 

exactly 1,500 :feet thick, and the contacts, top and bottom, are clearly defined; the red beds and the sandstone 

rest on an even surface of Flagstaff limestone, and the 

white to gray shale of the Green River formation overlies red beds of the Colton with slight gradation. The 

Colton strata, individually irregular and discontinuous, 

are of flood-plain and channel origin, whereas the enclosing strata, regularly bedded, are lacustrine,' and the 

striking contrast in color, a convenient criterion for 

recognition and mapping, represents a valid distinction 

between the two types of sediment. The stratigraphic 

limits of the Colton as thus given are of local value only; 

the strata of the two types intertongue extensively 

across the :region, and the entire Colton :formation west 

of Soldier Summit and the crest of theW asatch Plateau 

grades into beds of Green River type, as shown on 

figure 18. In this region, therefore, the- strata concerned evince most clearly their true character as lithologic, environmental units; chronologically the entire 

Colton is equivalent to part of the Green River formation. 

In the Wasatch Plateau and surrounding territory 

the Colton :formation is the highest of :four units that 

contain variegated beds; the others are the Morrison ( ~) 

formation, parts of the Indianola group, and the North 

Horn formation. Locally, where the structure is complex, it is difficult to identify these units surely on 

lithologic grounds alone. Although no general rule 

can be formulated, it is worthy of note that the colored 

beds of the Colton are commonly different from the 

others in their greater 1nonotony of color and in the 

predominance of deep reds. Especially noteworthy is 

the distinction between tlte Colton and North Horn , 

formations, formerly thought of as two similar members of the same :formation. The Colton displays, as 

a rule, very little delicate play of color, and as far as 

known it contains neither limestone nor coal. The 

North Horn contains not only variegated beds that 

range widely in color, with pale tints dominant, except 

locally in the western districts, but also abundant limestone in places and occasional beds of impure coal. 

The contrast between the two formations stands out 

clearly in the walls of Green River canyon, as may be 

seen in plate 23, A.- · 

DISTRIBUTION 

West of the type locality the Colton formation grades 

laterally into beds of Green River type, as described 

above. To the east it is extensively exposed in the 

Tavaputs Plateau. In the main body of the Wasatch 

Plateau it is almost entirely absent, and in the summit 

areas the Flagstaff is the highest unit exposed. At one 

locality, however, in sec. 7, T. 19 S., R. 6 E., Salt Lake 

Meridian, there are variegated beds above the Flagstaff in the western part of the Joe's Valley- graben 72 

that may be part of the Colton formation. On the west 

flank of the plateau the formation is present at the base 

of the Wasatch monocline in many areas between Salina 

and Mount Pleasant, and it is locally present in the 

Gunnison Plateau. In these western districts there is 

abundant evidence of intertonguing with both Green 

River and Flagstaff, and in large parts of the Gunnison 

Plateau the Colton seems to be absent. 

AGE AND CORRELATION 

The only fossils so far _found in the Colton formation 

are a few :freshwater mollusks, identified by _Reeside as 

members of the traditional Wasatch fauna. The ·same 

strictures as those applied to the interpretation of such 

fossils jn the underlying formations might here be 

suggested, but for one important fact-the collections .from the Colton contain none of the species found in 

the North Horn and Flagstaff that originally cast doubt 

on the Wasatch age of those strata. There is thus at 

present no paleontologic evidence to show that the Colton formation is not of Wasatch age (lower EoceneSparnacian of the European scale) ; nor, on the other 

hand, is there any paleontologic evidence to prove that 

it is '\Vasatch. No trace of vertebrate remains has been 

:found in the Colton strata, even after close examinati()::1 

of many excellent outcrops. 

The physical evidence is likewise uncertain. The 

nearest localities at which Wasatch vertebrates have 

been found are in southwestern Wyoming, where Cope 

first discovered fossils in the type Wasatch of Hayden, 

and in western Colorado, where Patterson73 has reported 

the Hyracotlwriwm (Eohippus) fauna. The relations 

between the Wasatch strata of these localities and the 

Colton of oontral Utah are not known, and considering the demonstrated complexity of stratigraphic relations in this part of the column where it has been 

studied in detail, comparison of sections seems futile. 

Without attempt at reviewing the available evidence, 

it may simply be said that the Colton :formation of 

central Utah is possibly Wasatch in age. 

12 Spieke-r, E. l\!., The Wasatch Plateati. coal field, Utah: U. S. Geol. 

Survey Bull. 819, pl. 32, 1931. In this publication neither the Flagstaff no]) the overlying beds at the locality mentioned were separated from 

the Wasatch as then defined; at the time when the locality was mapped the Flagstaff was thought to be a limestone in the lower member ot the 

Wasatch (North Horn of the present classification) . 73 Patterson, Bryan, op. cit. 
140 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 . 

GREEN RIVER FORMATION 

The term "Green River formation" as here used departs in no important sense from current usage. Such 

new facts as might properly be set forth in this paper 

are given in the descriptions of the Flagstaff and Colton 

formations. _ 

RECONNAISSANCE EAST OF WASATCH PLATEAU 

WEST TAVAPUTS PLATEAU 

In 1934 the writer examined in brief reconnaissance 

the country east of the Wasatch Plateau and north of 

the Bo?k Cliffs as fa~ as Green River, to trace out the 

formations here descnbed and connect them with a section earlier measured on Green River. Although not 

so c?mplete as had be~n planned, the work yielded a consider~ble body of fact that _is best presented here, 

along With the closely related Information on central 

ptah. It is separated from the foregoing because of 

Its more general nature. The stratigraphic relations 

observed are outlined in figure 18. 

. Betw-een Price C~nyon and the country east of Sunny- si~e, roughly. 30 miles along the Book Cliffs, the Price 

River forma~10n shows only minor variations in thick- ~ess and no Important change in lithologic character; 

In. gener~l appearance at the outcrop as well as in de- ta~ls ?f hthology the forma6on in the Sunnyside distnct I~ the same as that at the type locality, possibly excep~Ing the presence of somewhat finer-grained sandstone Ill the Castlegate member. On Green River however, as shown in the section given farther o~ the· Castlega~e is notably finer-grained, the beds abo~e it 

are ma..rine, and between these beds that are clearly 

identifiable as Price River and the North Horn formation there is a conglomeratic sandstone that appears to 

have no counterpart in the section of the western Book 

Cliffs. One aim of the reconnaissance was to discover 

the relations between the beds of the two sections but t~e change was found to occur in country too rugged and 

difficult of access for the facilities available. 

In the western stretch of the Book Cliffs the North 

Horn formation undergoes ~o ir;nportant, lithologic 

change, but decreases notably In thickness as shown in 

figure 18. The Flagstaff limestone, about 6oo feet thick 

in Price Canyon, vaguely separable from the North 

Horn formation but sharply set off from the overlying 

Colton, continue~ eastw~rd !'Vithout notable change from 

Colton as far as the main highway along Willow Creek 

' north~ast. of Castlegate; farther east there is intertonguing In which about 300 feet of limestone and shale 

ch~nge to red shale and sandst.one of the Colton type. 

Still farther east all ~h.at remains of the Flagstaff is a 

calcareous zon~ containing only a few well-defined limestone ~e~s; ~his ~one was ~raced as far as Sunnyside, 

where Jt Is a barely recognizable remnant. , 

_For ·about 20. miles east of Colton the Colton-Green 

River_ contact IS regular, ~i~h no imp_ortant intertongumg. In the first 12 miles of this stretch the contact, is easily traceable in the hills north of the old Colton-D_u~hesne road, but farther east it crosses a very 

:ugged d~v~d~ to the hea:dwaters of Minnie Maud Creek, 

In th~ VICinity of whiCh there may be some intertonguing that has escaped notice· however as well as 

could be determined in reconnaiss~nce not ~uch inter- to~gu_ing is possible. Along the upper reaches of 

MI;nnie Maud Creek, 20 to 25 miles east of Colton, a 

unit of b:own sandstone and gray shale, flood-plain or 

delta sediments of the Colton type, appears about 200 

to 250 feet above the base of the Green River formation 

and becomes 200 feet thick. This unit may be equivalent to the tongue of Wasatch strata described by Bradley 74 in his section of the Green River deposits for 

Indian Canyon, not far to the northwest. Traced ,eastward down Minnie Maud Creek, this unit begins to 

contain red beds, becoming characteristically Wasatch,· 

and about 33 miles east of Colton 100 to 200 feet more 

of W asatchlike beds appear at ·the top. At this place a 

zone of red beds 50 to 75 feet thick occurs 300 feet 

higher in the Green River. A short distance farther 

downstream the whole interval here involved is more 

like the Wasatch than the Green River, with many thin 

beds of lacustrine material scattered through the section; the intertonguing is very intricate in detail. 

Traced toward Green River, these beds plunge under 

the surface and the lower course of Minnie Maud Creek · is an imposing canyon in Green River strata. (See 

pl. 23, B.) At the place where they plunge under, however, the beds are so closely similar to those originally 

called Wasatch in Green River Canyon that there is 

little doubt they are approximately the same. The 

contact veers southeastward toward Green River into 

the rugged country that was not penetrated in this 

reconnaissance. Unless there is some unexpected 

irregularity in this region, then, the contact between 

Colton and Green River is roughly 1,000 feet higher, 

stratigraphically, at the Green River than at Colton. 

GREEN RIVER CANYON 

In 1925 Reeside and the writer made a reconnaissance trip up the canyon of the Green River from Green 

River, Utah, to examine the late Cretaceous and early 

Tertiary rocks. Above the Castlegate sandstone member of the Price River the following section was found: 

Section of post-Oastlegate rocks on Green River between Desolation Oanyon and Range Oreek 

Green River formation. 

Colton formation: 

1. Sandstone, deep buff to golden brown and brownish 

red; in massive ledges with interbedded red shale 

Feet 

/ (estimated) --------------------------- 1, 100-1, 300 

2. Sandstone, massive, buff to yellow, weathering brown; forms single cliff (estimated)__________ 350 

3. Shale, maroon, with interbedded buff to brown 

sandstone; irregular in detail but fairly regular in larger units (estimated) ____ __:-________ -\----- 350 

Disconformity'l 

North Horn formation: 

4. Shale, gray to variegated; sandstone, gray, brown, 

green; some conglomerate; zone of limestone 55 

feet below top_______________________________ 395 

Disconformity? 

Tuscher ( ?) formation: 

5. Sandstone, gray, cream, white, mostly coarse, in 

part conglomeratic; little shale~-------------- 215 

Disconformity. 

Price River formation: 

6. Sandstone, gray, medium (estimated)___________ 200 

7. Sandstone, gray, medium, with pockets of gray shale; forms ledges__________________________ 250 

8. Sandstone, buff; prominent regular beds of gray shale up to 10 ft. thick_______________________ 100 

9. Sandstone, buff, massive ; irregularly bedded; few 

shale partings; forms persistent cliff, grades into 

unit 10-------------------------------------- 125 

10. Sandstone, gray to brown ; shale, gray to black ; 

oyster reefs common, zone marine fossils 75-100 

ft. above base; lower 75 ft. dominantly marine 

shale_~-------------------------------------- 300 

Castlegate sandstone member. Total ____________________________________ 3,385-3,585 

n Bradley, W. H., Origin and microfossils of the oil shale of the 

green River formation of Colorado and Utah: U. S. Geol. Survey Prof. _ aper 168. p. 17, 1931. 
(/} 

U) 

<( 

a::: 

::l 

-, 

Q) 

.-.4 

+' 

{I) 

Minnie Maud Creek 

,=--:==r=;=.' -- _' = 

:a 

H 

--· 

,__.._ . ~- .. · .. · . 

- ·-<~ : :· ~-:? ~ 

.• ·--;---;-.- .. ---. .:.. 

~- ---·. 

_:_ -

Emery sandstone mem oer of Mancos 

EXPLANATION 

Kt = Tuscher formation 

Horizontal scale 

Km b=Buck tongue of Mancos shale 

Vertical scale 

? ... 

::-:-""' __ ..__..-= 

10 0 20 Miles 1000 0 5000 Feet 

( 

FIGURE lB.-Stratigraphic diagram, northern Wasatch Plateau to Green River. The Indianola group of this section may include the equivalent of the Morrison ( ?) formation as its basal part. The Morrison(?) is recognized near Thistle, but it has not been distinguished in the 

district south of Thistle, which this section is intended to represent, and it is therefore not differentiated in this figure. 

I . ~ _· ' . 

>- 0::: 

<( 

rrr 

w 

I0::: 

w 

a.. 

a.. 

:::l 

(/) 

:::l 

0 

w 

0 

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w 

0::: 

0 

~ 

~ 

~ t:r.l 

[/). 

0 

N 

0 

~ 

0 

>' z 

t::; 

t:r.l 

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z 

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142 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 r 

Units 1 to 3 of this section are classified as the Colton 

formation. They correspond well in lithology and 

thickness with the Colton strata on Minnie Maud Creek, 

not far to the northwest. Unit 4 underlies these beds in 

sharp contrast; it corresponds well with the North 

Horn formation as seen in the Sunnyside district, to 

the west, and it may contain the equivalent of the Flagstaff. However, there is no definite zone of limestone at 

the top of the unit, and the only Flagstafflike bed is a 

gray limestone 15 feet thick, 55 feet beneath the top, 

underlain by shale containing thinner beds of limestone ; these beds are like the limestones scattered 

through the North Horn formation in the western 

Book Cliffs, and when the section was measured they 

were not even thought of as possible Flagstaff. The 

whole unit contains much lacustrine sediment and is 

set off sharply from the overlying red beds of the Colton 

(see pl. 23, A) in a contact similar to that between 

Flagstaff and Colton farther west. Strong discontinuity is evident, and disconformity not unlikely. 

Unit 5 is almost certainly the Tuscher formation 75 of 

Fisher's section in the eastern Book Cliffs. Although 

it has not- been connected by tracing with well-ascertained outcrops of the Tuscher to the south, it agrees 

so well in lithologic character, thickness, and stratigraphic position with the formation as defined by 

Fisher that the correlation is fairly sure. The place of 

the Tuscher in the Price River-North Horn succession 

of' the western Book Clift's, however, is not settled. 

Stratigraphic evidence on Green River, as well as that 

observed by Fisher in the Book Cliffs, suggests alliance 

of the Tuscher with the overlying rather than the underlying strata, and the writer's present conclusion is 

that the Tuscher is a coarse basal phase of the North 

Horn formation. This still leaves a question, however, 

concerning relationships to the west. Along Green 

River the Tuscher is disconformable on the underlying 

Price River formation and contrastively different, 

whereas in the western part of the Book Cliffs there is 

no apparent break between the Price River and North 

Horn formations. Throughout the eastern Book Cliffs 

the base of the Tuscher marks the first strong change in 

the Cretaceous section above the Mancos shale, and it · would seem to signify a break of regional importance. 

This horizon must be located in the section of central 

Utah before the major outlines of the regional history 

can be clearly drawn. 

Units 6 to 10 of the section constitute the upper member of the Price River formation. The upper part of 

unit 10 is the Sego sandstone member of Fisher's section and the lower is the Buck tongue of the Mancos. 76 

CRETACEOUS-TERTIARY BOUNDARY PROBLEM 

GENERAL CONSIDERATIONS 

The division between Cretaceous and Tertiary given 

in the foregoing stratigraphic scheme implies ·the assumption that this major boundary lies between the 

uppermost occurrence of dinosaurian remains and the 

lowermost occurrence of placental mammals. Although 

most students of this part of the stratigraphic column 

are probably coming to recognize this as the most logical 

dividing line between Cretaceous and Tertiary, there is 

not complete agreement, and to treat the matter as 

settled without any supporting discussion would constitute an unwarranted presumption.' The problem has 

given rise to very extensive discussion, and yet in all the 

literature touching upon it there is remarkably little 

overt statement of the fundamental principles involved. 

The general questions of geologic chronology and subdivision, on the other hand, have been freely discussed 

in a considerable number of articles and books, especially in recent years, and there is abundant basis for 

consideration of general principles, even if the status 

of knowledge on many phases of the complex question 

is not fully clear. To the writer's knowledge no atten1pt 

at summary application of fundamental principles to 

the· Cretaceous-Tertiary problem has been made. The 

new-found facts for central Utah contribute definitely 

to one phase of the subject, at least, in that they put the 

question of relation between the physical history and 

the fossil record in entirely new light. 

For these reasons the writer ventures a discussion of 

the problem in the light of general principles-not an 

exhaustive treatment, nor yet a complete defense of the 

stand taken in this paper, but rather an examination 

of certain governing principles and concepts that seem 

to be crucial. In scientific investigation, and especially 

in such dominantly fact-finding activity as that of the 

geologist, it is worth while to pause occasionally in 

review of the fundamental basis on which results are 

being built up, and even in critical examination of elementary principles or postulates that seem virtually 

axiomatic. Too often familiarity with given lines of 

procedure leads to acceptance of concepts, methods, and 

interpretations without rigorous understanding of the 

nature of the basis on which they really rest. Especially 

does this tend to be true with respect to controversial 

subjects such as the present one, essentially the Laramie 

problem, in which part of the disagreement has arisen 

over elements of the evidence for which the fundamentally logical values have apparently not been thoroughly scrutinized. 

The Laramie problem, one of the famous issues in 

the history of North American geology, has been sufficiently reviewed,77 and requires no summary here. It 

is enough to recall that the discussion, starting with 

sweeping assignments of all western coal-bearing strata 

to either Cretaceous or Tertiary, and then centering on 

the paleontologic and paleobotanic evidence, began in 

later years to involve the physical evidence, especially 

the existence and interpretation of unconformities and 

the attempt to locate in the stratigraphic column the 

horizon of the major orogenic episode. Probably most 

geologists agreed in the concept that the great disturbance marked the close of the Mesozoic era, 78 and some 

held that profound orogeny must be world-wide jn 

effect, hence simultaneous; furthermore, that such 

orogeny, in its controlling influence on geographic and 

biologic conditions, must produce strong widespread 

punctuation in the record, and therefore must logically 

be recognized as the prime basis for major chronologie 

subdivision. Under this concept the location of the 

major physical break in the column was of prime 

importance, but in the sections that afforded good 

fossil evidence the physical relations were the source 

76 Fisher, D. J ., The Book Cliffs coal field in Grand and Emery Counties, Utah : U. S. Geol. Survey Bull. 852, p. 20, 1936. 76 Fisher, D. J., op. cit .. pp. 15-16. '1'1 For summary and bibliography see the following papers : Knowlton, F. H. 1- The Laramie flora of the Denver Basin: U. S. Geol. 

Survey Prof. Paper 130, 1922. Dobbin, C. E., and Reeside, J. B., Jr., 

The contact of the Fox Hills and Lance formations: U. S. Geol. Survey PrO'!. Paper 158, pp. 9-25, 1929. Russell, L. S., The CretaceousTertiary transition of Alberta : Royal Soc. Canada Trans., 3d ser., vol. 

26, sec. 4, pp. 121-156, 1932. 78 See, for example, Blackwelder, Eliot, A summary of the orogenic epochs in the geologic history of North America: Jour. Geol., vol. 22, ~· 647, 1914; and textbooks of historical geology. 

/ 
\ 

LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL UTAH 143 

of much disagreement. Unconformities between zones 

of different fossil content, argued as valid division 

lines and held by some geologists to be of prime 

physical significance, have been shown by Dobbin and 

Reeside 79 to be susceptible of quite diffeTent interpretation. Among lines of evidence needed for adequate 

survey of the problem, a most important item was precise and certain determination of the position in the 

stratigraphic column of the major episode or episodes 

in the Laramide orogeny. -

The evidence now available in central Utah meets 

this need for part, at least, of the North American 

Cordillera. 'I'he major Laramide folding in this area 

took place a long time before any of the importantchanges in the fossil record that have been argued as 

division markers, and the relative significance of these 

two types of event must be evaluated in a decision on 

the boundary problem. Distinct and independent, instead of simultaneous and interrelated, they cannot 

both be given weight; and as the Utah evidence is 

scanned the choice seems naturally to fall on the pal eontologic. basis, for the time of orogeny now ascertained , lies too far within the bou;nds of typical Cretaceous to 

seem possible as a division marker. This decision inv:olves an assumption as to what constitutes typical 

Cretaceous, a concept that is briefly examined, in another connection, below. If it be granted for the moment that typical Cretaceous can be recogniz·ed and 

that the upper part of the Montana group is clearly of 

that type, then if the boundary is to be placed at an 

upper limit of typical Cretaceous the earliest strong 

Laramide orogeny in central Utah falls out of consideration as a boundary marker. More · than that, the 

orogeny came at a time that witnessed no marked faunal 

change and no physical change other than the folding 

itself and its immediate effects, which were local. It 

would seem to be ruled out as a marker of anything 

significant in either the stratigraphic succession or the 

time scale ·as generally conceived. 

There were other strong movements, however, in the 

Laramide belt during the passage from typical Cretaceous to typical Tertiary, notably the one in the Rocky 

Mountains of Montana and Alberta that probably came 

between the Fort Union and the Wasatch. The question might still be raised whether this movement provides significant basis for a division, despite the fact 

that the anomalous position of the central Utah orogeny 

weakens the thesis in general and at least adds to the 

application of the principle another complication, that 

of differentiating between orogenies as to their relative 

significance. 

lated a cyclic periodicity. So compfehensive a generalization would make without question a most satisfactory basis for subdivision. When the available data 

are assembled,80 it is evident that the time pattern of 

the earth's orogenic performance does not match the 

pattern of subdivision based on fossil succession. The 

paleontologic evidence, critically examined, yields uncertainties amply emphasized in the boundary disputes 

that have arisen over every important division in the 

scale. These uncertainties have arisen in large part ou 

of the attempt to continue the use of fossils along lines 

based on older concepts of sweeping change, in the face 

of newer knowledge that is out of harmony with those 

concepts. In general, as the body of geologic fact has 

increased, as gaps have been filled and crudities replaced 

by refinement, the appearances of regularity and uniformity on which many of the older concepts were 

founded have faded away. · As to the relative values for subdivision inherent in 

the physical and organic records, to the extent that past 

experience may point the way, decision between the two 

is implicit in the standard scale against which the orogenic succession is laid; in the development of this scale 

the fossil evidence has been paramount. However, this 

does not in itself necessarily deny to the orogenic record 

any place in the formulation of boundaries, and the 

point may not be dismissed without some consideration 

o:£ the facts now available. 

Before considering specifically) certain pertinent 

features of the physical and organic records, it is important to recognize the distinction between correlation 

and subdivision. Most existing discussion of the diverse 

evidence has laid stress on the question of validity for 

correlation. Validity as a criterion for subdivision is 

another thing, and the two have not always been carefully distinguished in discussions of boundary problems. A given criterioni granted it be valid for subdivision, must be accurate y correlatable throughout the 

world, and without inquiring further, at this point, as 

to the special significance tg be sought in a valid criterion for subdivision, it appears well to examine the 

values inherent in orogenic disturbances as regards 

contemporaneity. 

THE OROGENIC RECORD 

Stille 81 and Bucher 82 have come to the conclusion that 

the important orogenic pulsations of the earth's crust 

have been sharp, simultaneous over the . 'vorld, and 

separated by much longer periods of quiet. If this is 

true, orogeny might provide the most accurate means 

of correlation yet available, and in light of the rather 

QUESTION OF BASIS FOR TIME DIVISION _ re,.gularly increasing frequency of the pulsations toward 

the present, the pattern of orogenic succession might 

afford the most logical framework for a time scale. It might be well here to raise the question, Is there, _ after all, a valid general basis for the subdivision of 

geologic tiJUe ~ And secondarily, if there is a basis 

usable to characterize the larger subdivisions, can it be 

applied to the exact determination of boundaries~ Logically, such basis ought to be some fairly definite expression of natural law, but when the geologist searches the 

data of his science he finds no well-established law to 

guide him; rather, he finds only the cumulative result 

of empirical experience in which many elements conflict. Originally the plan of the time scale did imply 

natural law-a comprehensive generalization that 

united profound, world-wide physical disturbances with 

sweeping changes in the living world, and that poshtThat many of the orogenic episodes have been relatively short seems well established, although some 

whose age relations are well determined seem to have 

been drawn out over considerable periods of time. In 

order to determine this point it is obviously necessary 

to fix the date of a given orogeny within adequate time 

limits, and many that meet this requirement, such as 

the early Laramide and the pre-Flagstaff movements 

of this paper, were unquestionably much shorter in 

79 Douuin, C. E., and Reeside, J. B., Jr., op. cit. so Stille, Hans, Grundfragen der vergleichenden Tektonik, pp. 154-

16a, Berlin, 1924. " 1 Stille, Hans, op. cit., pp. 44-45. 82 Bucher, W. H., 'l'he deformation of the earth's crust, pp. 414-416, 

Princeton, 1933. 

\ 
144 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

duration than the intervening periods of quiet. It 

must be recognized, however, that most of the evidence 

on orogenic dates marshalled by Stille. 

83 is inadequate 

to prove global episodicity; the ages of the limiting 

strata are generally too far apart. It must also be 

recognized that some orogenies, such as the mid -Creta-ceous movement of this paper and the early Jurassic 

folding of east-central N evada,84 seem possibly to have 

been somewhat protracted. In a comparative sense, 

however, even these movements were probably shorter 

than the intervening periods of quiet. 

In a paper questioning the periodicity of diastrophism, Shepard 85 has postulated essential continuity of 

orogenic activity since the pre-Cambrian. Shepard's 

argument against periodicity seems to be sound, and 

his insistence on the inaccuracy with which most orogenies are dated is thoroughly justified, but the evidence hardly demonstrates continuity-rather multiplicity. Evidence in support of episodic character has 

recently been brought out for a most important region, 

California,86 the exceedingly complex structural' development of which might easily suggest continuity of 

orogenic process. In general, it seems a fair conclusion 

that orogeny has been for the most part episodic rather 

than protracted or continuous in nature. 

Demonstration that the sharply defined episodes are 

simultaneous, however, rests finally on paleontologic 

evidence, which, as pointed out by Bubno:ff,87 is itself 

not unimpeachable. It should further be observed that 

many of the episodes cited · by Stille are by no means 

closely dated; some, perhaps, not reliably. For example, in his listing of the Laramide orogeny Stille 8 8 

accepts for the first movement in North .. America the 

age given by Blackwelder 89 simply as the close of the 

Cretaceous. Bucher later cited, as indicative of the 

early Laramide movement, the unconformities at the 

base of the Colgate member of the Fox Hills sandstone 

in eastern Montana and between the Laramie and 

Arapahoe formations of the Denver Basin, correlating 

this break with the early Laramide movement of 

Europe as classified by Stille. 90 The correlation of the 

unconformities between Montana and Colorado has 

been shown by Dobbin and Reeside 91 to be probably 

incorrect, and the contact between the Laramie and the 

Arapahoe formations has been shown by Lovering 92 

to signify no great orogenic movement, rather local 

uplift of little significance. Further, the LaramieArapahoe contact lies well above the horizon of the 

Fox Hills-Lance transition and is thus probably not 

contemporaneous with the Maestrichtian-Danian movement specified by Stille as the early Laramide. The 

dates of the movement in Europe cited by Stille as 

Laramide are in large part not closely determined,93 

and this is true as well in other parts of the world. In 

order to show at a glance the value of the European 

evidence, the writer has prepared figure 19 according 

to the data given by Stille. In this alinement it is 

evident that the only place where the two movements 

assigned to the Laramide are accurately and certainly 

dated is in the Mons region, where the disturbances on 

the Artois axis were weak. 

Further, Stille's assignment of the second Laramide 

movement 94 does not coincide with the time of strongest 

Laramide movement in the Rocky Mountains of Montana. In the Mons region of Belgium this movement 

came, as cited by Stille, between the "upper Mons" 

(lower Thanetian of general usage) and the lower LanTERRITORY STAGES 

c 

c "' ~ c "' ..c c; Ill ·;: u c "' ·u 

"' i c "' ~ "' a. "' ~ E E ·c: c c 

"' "' "' "' "' 0 ..c a. (.) :::i'! 0 ~ 1- en 

French Alps .... ___________ ·_ 

Eastern Alps _____ ____ ___ _ 

Central Alps __ _____ _____ _ 

Southern Alps .. __ __ .... ___ _ 

Julian pre-Alps __ __ ______ _ 

Macedonia---- --- - - -----

Northern Germany -------

Paris Basin-Belgium _____ _ 

Mo~s region ______ .. __ ___ _ 

Southern Pyrenees ___ ___ _ 

CataloQian border .. .... ........ .. 

Andalusia ---- --- -------- ? - ·-?-? 

Balearic Islands .. .... ______ _ 

Southern Caucasus __ __ __ _ 

Northern Atlas ___ _______ _ 

Southern Atlas_ _________ _ ?---? 

Gl 

c 

Gl 

u 

0 c c w "' "' ·u; 

~ i ! a. ::l a. >- ...J :J 

INTENSITY 

OF 

DISTURBANCE 

Weak. 

Strong. 

Moderate. 

Weak. 

Weak. 

Very weak. 

Strons, local. 

Local. 

Egypt.... ............ .. .................... Gentle. 

Asia Minor _____ ..... ______ Local. 

East Aegean Mts .... __ ........ 

Bithynian peninsula _____ _ 

Northern Syria ------- .. . __ 

FIGURE 19.-Age determination of Laramide orogeny in Europe. The 

list includes only regions for which reasonably accurate stratigraphic data are available. The lines extend between the youngest known 

folded stra t a and the oldest known nonfolded. After Stille. 

denian (upper Thanetian or Cernaysian). These stages, 

as well as they may be correlated with the North American section, are equivalent to the middle Fort Union 

and the Clark Fork, respectively, and in any event are 

earlier than the true Wasatch, or Sparnacian.95 In the 

Rocky Mountain districts of Montana and Alberta the 

major orogenic impulse came after the latest Fort Union 

(Clark Fork; upper Paskapoo of Canadian geologists 96 ) 

and perhaps before the Wasatch, although the upper 

limit is not clearly proved to be any earlier than late 

Eocene. 97 The discrepancy between thes~ determina-

• 3 Stille, Hans, op. cit., pp. 62-210. 84 Ferguson, H. G., and Muller, S. W., Early Jurassic orogeny in west- central Nevada: Geol. Soc. America Proc. 1936, p. 71, 1937. • Hs Shepard, li'. P., To question the theory of periodic diastrophism: 

Jour. Geology, vol. 31, pp. 599, 602, 613, 1923. 86 Reed, H.. D., and Hollister, J. S., Structural evolution of southern 

California : Am. Assoc. Petroleum Geologists Bull., vol. 20, pp. 1597, 

1691, 1937. . 87 Bubnoff, S., Grundprobleme der Geologie, pp. 137-142, Berlm, 1931. 88 Stille, Hans, op. cit., p. 155. ' 89 Blackwelder, Eliot, Handbuch der regionalen Geologie, vol. 8, pt. 2, 

pp. 62, 141, 159, Heidelberg, 1912. " 0 Bucher, W. H ., op. cit., !Jp. 406- 411. DI Dobbin. C. E .. and Reeside .. T. B ... Tr .. The contact of the Fox Hills and Lance formations: U. S. Geol. Survey Prof. Paper 158, pp. 9-25, 

1929. u2 Lovering, T. S., Geologic history of the Front Range, Colorado : Colorado Sci. Soc. Proc., vol. 12, no. 4, pp. 91·-92, 1929. oa Stille, Hans, op. cit., pp. 156-162. u4 Stille, Hans. op. cit., p. 160. o5 Woodring, W. P., and Gazin, C. L., in Stratigraphic nomenclature 

in the United States : 16th Internat. Geol. Cong. Guidebook 29, pl. 9, 

1932. Bubnoff, S., Geologie von Europa, vol. 2, pt. 2, p. 1020, table 12, 

Berlin. 1935. · IJG Russell, L. S., The Cretaceous-Tertiary transition of Alberta : Royal Soc. Canada Trans .. vol. 26, sec. 4, pp. 148-151, 1932. ur U'raser, F. J., McLearn, F. H., Russell, L. S .. Warren. P. S., and 

Wickenden R. T. D., Geology of southern Saskatchewan: Canada Geol. 

Survey :M:em. 176, p. 119, 1935. Russell, L. S., and Wickenden, R. T. D., 

An upper Eocene vertebrate fauna from Saskatchewan: Roy. Soc. Canada 

Trans., 3d ser., vol. 27, sec. 4, pp. 53-65, 1933. 
LATE MESOZOIC AND EARLY CENOZOIC HISTORY OF CENTRAL UTAH 145 

tions is sufficient to raise question concerning simultaneity. If there is inclination to allow for inaccuracy 

in the long-range stratigraphic correlation, it might be 

borne in mind that the Sparnacian mamma.ls are probably more closely correlated between Europe and North 

America than are any others; 98 and, as far as such 

pf}leontologic evidence is valid for correlation, it would 

seem to hold good in this instance. The correlation of 

the underlying Cernaysian with the Tiffany and Clark 

Fo:r:k b~ds ~f North America, as given by Matthew,99 · 

seems likewise strong. -

It should also be noted that the ti1nes of at least two 

out of three strong orogenic disturbances recently determined in the western United States appear to have 

no counterpart in Stille's table. The early Laramide 

movement described in this paper, rather accurately · placed in the local section, came at a time which, even if 

not precisely referable to the European time scale, is 

clearly different from the two nearest in Stille's list. Of 

these the older, the Wernigerode phase of the Subhercynian orogeny/ is Santonian in age, corresponding 

to late Colorado (Niobrara) of the western American 

column,2 or the middle part of the Mancos shale in 

Utah; this correlation is fairly well established by characteristic marine faunas. The next younger of Stille's 

list, the "early Laramide," falls between the Maestrichtian and the Danian of the European scale, corresponding approximately to the upper limit of the ~fontana 

group in the American section, or the boundary between_ the Fox Hills and the Lance formations of the plains 

section. This horizon is not accurately located in the 

Utah section, but it certainly lies above the base of the 

Price River formation. The main Laramide folding 

of central Utah came between middle and late Montana 

times, probably in the late Campanian of the Europea1; 

scale. With adequate discount for uncertainty in correlation with the European section, this folding is unquestionably later than the Subhercynian and almost 

certainly earlier than the "early Laramide'' movement 

of Stille. ' 

, -The other. two American orogenies that fail to agree 

are those reported by Ferguson and Muller' 3 for western 

Nevada; these fall in the Karnian stage of the Triassic 

and in the late Liassic stage of the Jurassic. Stille's 

grouping shows nothing for the Karnian, his earlv 

Cimmerian folding coming between the Norian ancl . Rhaetian.4 For the Lias he records questionably a disturbance in the Donetz district, but as reported by 

Borissjak 5 this folding preceded the upper Lias .. Comparison . with the Liassic folding of Nevada is not so 

clear as the others here given, because the Nevada folding seems to have continued through Liassic time, and 

the Donetz folding ·may coincide with part of it, but if 

the report is correct it came before the end of the Lias, 

the time of maximum disturbance in Nevada. 

Another difficulty in the way of visualizing the significance of Stille's grouping is presented by the problem of distinguishing between true orogenic movements 

and warping of epeirogenic nature. Most of the in- , stances of Laramide folding outside of North America 

are far from profound, and many involve only slight 

discordance. The writer is inclined to agree with Pia 13 

that such minor discordances, should they happen to 

occur at times of no great orogeny elsewhere, would be 

classed as epeirogenic. Stille's criterion 7 for the discrimination between minor warping movements of 

orogenic nature and those of epeirogenic origin is to 

classify as orogenic those that occur at a time of strong 

orogeny elsewhere. This merely begs the question; the 

occurrence of such JV,inor movements at times of orogeny 

may not be fortuitous, but if no other positive criteria 

are available for distinction· from movements o£ truly 

epeirogenic nature, _such occurrences add little to the 

argument .for widespread contemporaneity of orogeny. 

At all events, to connect the epeirogeny causally with 

the orogeny does not help matters for the Laramide 

epoch, because the orogeny, as now known, began long 

before the general emergence of North America. 

It seems that the hypothesis of orogenic simultaneity 

is not well enough established to be relied on either in 

correlation or the establishment of divisions in the time 

scale. This is not to say that simultaneity has not p'revailed ; obviously; if orogenic process is due to some 

pervading, ·nonsporadic condition of episodic character 

in the earth's internal mechanism, it might well be 

simultaneous. TP,e fundamental cause of orogeny, 

however, is not well enough understood to serve as basis 

for such a superstructure of r~asoning. 

T~E EPEIROGENIC RECORD 

Epeirogenic movement would appear to fall in a different category from orogeny, empirically considered, 

in evaluation of bases for division. Although there 

have been orogenic disturbances within the time intervals occupied by the great epeirogenic movements 

that have caused extensive recessions of the sea, inspection of the orogenic chronology presented in' this paper 

reveals little or no evident relation between the two 

types of movement for the late Mesozoic and early · Cenozoic of North America. If the orogenic succession 

affords no immediately acceptable basis for subdivision, 

perhaps the broader and slower pulses of epeirogenic 

movement might embody some feature \vhich would 

serve to provide a purely physical basis. 

Especially does this seem worthy of consideration for 

the division between Cretaceous and Tertiary; which is 

often thought of by geologists as the most clear--cut in 

the whole scale 8

-a concept that results from the extensive epeirogenic movement that occupied the latest 

stages of the Cretaceous and the earliest of the Tertiary. 

Widely over the earth the sea began to retreat from 

dominant-basins of Cretaceous deposition in Maestrichtian time (late Pierre and Fox Hills of the United 

States), not to return generally until well after the 

beginning of the Tertiary. This gave rise, in nonorogenic areas all over the world, to stratigraphic c0ntacts at which typical Cretaceous fossils are pitted contrastively against typical Eocene, a phenomenon of 

omission that permitted the initial concept of sharp 

boundary between the eras. ]?ossi bly the culmination 

or maximum of this widespread · marine retrogression 

might serve as a logical boundary, if it could be located 

and accuratelJ correlated across the earth, but here 

again there 'is uncertainty that bars further consideration. The only known place in the ~orld where it seems 

98 Scott, ,y, B., A history of land mammals in the Western Hemisphere, 

p. 108; 1913; idem, 2d ed., pp. 224-226, 1937. ~ .afatthew; W. D., Fossil vertebrates and the Cretaceous-Tertiary problem: Am. Jour. Sci., vol. 2, pp. 209-277, 1921. 1 Stille, Hans, op. cit., p. 152. · 2 Reeside, J. B., Jr., Stratigraphic nomenclature in the United States: 

16th Internat. Geol. Cong. Guidebook 29, pl. 8, 1932. 3 Ferguson, H. G., and Muller, S. W., Early Jurassic orogeny in west- central Nevada: Geol. Soc. America Proc. 1936, p. 71, 1937. 4 Stille, Hans, op. cit., pp. 133-138. · 5 Borissjak, A., Uber die Tektonik des Donez-Hohenzuges in seinen 

nordwestlichen AusHiufern : Centralbl. Mineralogie, 1903, p. 645. n Pia, J., Grundbegriffe der Stratigraphie, p. 78, 1930.- 7 Stille, Hans, op. cit., p. 16. 8 Bubnoff~ S., Gl'undprobleme der Geologie, p. 132, 1931. 
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

possible to recognize clearly a horizon of maximum retrogression is in Belgium, and · even there it would be 

difficult to be sure of a valid maximum. According to 

Bubnoff's summary, the passage from the Danian to 

the Montian seems to mark the greatest withdrawal of 

the sea,9 but the Montian transgression was very slight 

and was followed by a withdrawal. The last marine 

beds in the western interior of the United States, the 

Cannonball marine member of the Lance formation, 

appear to mark the end of the late Cretaceous retrogression there, but evidence o£ the turning point, the beginning of the marine invasion, is lacking; marine succes- sions elsewhere in North America lack an equivalent 

of the Cannonball, and probably also the stage immedi- , ately following. It would be difficult to establish a basis 

for subdivision on purely epeirogenetic grounds, although it must be recognized that If a purely physical 

basis is to be sought, one founded on the widespread 

swings of epeirogenic movement would seem most 

Logical. . 

THE PALEONTOLOGIC RECORD 

The various values of fossils as markers of geologic 

time have been widely discussed in recent years, in 

special treatises as well as in papers devoted to individual cases of correlation and subdivision/0 more largely by European authors than American. Perhaps the 

most thoroughgoing attempt to bring together the really 

fundamental concepts is that of Bubnoff.U Out of the 

entire discussion, necessarily complicated because of 

the large number of variable factors and the uncertainty 

that still invests many fundamental assumptions, there 

seem to emerge two general principles. First, there is 

nothing inherent in fossil occurrences that will serve ·without question as indicative of contemporaneity. 

Second, when all possible conditions of occurrence and 

interpretation are evaluated and a balance of probabilities is struck, fossils afford t9-e surest means yet 

available for correlation. 

But, as pointed out in a foregoing paragraph, corr·elation is not exactly the same as subdivision, and the 

problem here considered is one of subdivision. The fact 

that a given criterion, either paleontologic or physical, 

affords adequate means of correlation does not necessarily ensure that it will serve as valid basis for subdivis'ion. For example, if major orogenic movements 

should be demonstrated to be simultaneous across the 

ea.rth and hence usable for accurate correlation, they 

might still fail to set the column off into rational divisions. In fact, the evidence reviewed in this paper 

suggests that with respect to other physical aspects of 

the record, such as the stratigraphic, and especially with 

respect. to the fossil record, .the orogenies would probably make a poor basis. At least they would have to be 

independent; and they are not sufficiently widespread 

to serve alone. Donceivably also certain groups of fossils, as for example the ammonites, superior for correlation, might not stand alone as adequate basis for major 

subdivision. 

There is involved in this, evidently, an unstated assumption as to the end to be gained in subdivision. The 

major units in the scale have been handed down through 

generations of workers, and the basis on which they rest 

has been more or less axiomatically accepted from one 

generation to another as a combination of physical and 

organic characteristics expressive of that homogeneity 

and distinctness generally associated with time divisions 

in any order of magnitude. In this the concepts of unity 

and distinctness are the essential elements, and if no 

specification is laid down as to whether the characteristics shall be organic, or physical, or both, they seem to 

embody a sound general basis for approach to the whole 

question of subdivision. The two concepts, of unity on 

the one hand and of distinctness on the other, give rise 

to two orders of problem-the determination of major 

unifying features, and the selection of those features 

that will best serve, in the interest of distinctness, to define exact boundaries. Solution of the second order of 

problem, the major concern here, should naturally be 

founded on the characteristics of the first. Regardless 

of which elements in the total field of possible criteria 

afford the best means of correlation,· the basis chosen for 

the drawing of a boundary should conform as well as 

possible to the natural scheme on which the entire division is set up. .' . Inasmuch as fossils seem to afford the best means of 

correlation, and in view of the obvious discrepancy between the fossil record and the order of physical events 

(barring perhaps the epeirogenic), it would seem best, 

if feasible, to make the division on the basis of some 

characteristic of the fossils that affords a logical turning 

point. 

In fact, if the question is raised as to what the terms 

Cretaceous and Tertiary actually mean, one does not 

go far into the available facts before it is evident that 

they have come to stand essentially for times in the 

geologic past when more or less characteristic organisms lived. On this basis a logical boundary would 

naturally come at the horizon of greatest change between the types, and this principle has been most 

widely adopted by students of the problem. It is 

necessary to decide, however, whether the discernment 

of greatest change shall be attempted for the entire assemblage of known organisms, as a sort of average, 

or for a single group selected because of outstanding 

distinctiveness or inherent value in correlation. Both 

principles have been applied in the discussion of 

boundary problems. It is not uncommon for the greatest changes in different groups of organisms to come at 

different horizons, as has been pointed out by Schindewolf 12 for the passage from Devonian to Carboniferous. In such cases, if summation or averaging is 

difficult, the tendency naturally is to select a most significant group, as Schindewolf has done in the case 

cited. In the Cretaceous-Tertiary transition the outstanding changes in fossil succession seem in part to · follow this rule. Of characteristic Cretaceous forms 

the ammonites disappear first, at ·the top of the Fox 

Hills, equivalent to the close of the Maestrichtian, and 

the genus I noceramu.s does not occur in the Danian_; the 

dinosaurs disappear at the top of the Lance, equivalent 

to the close of the Danian. The fresh'-vater mollusks 

have been considered to undergo no striking change in 

the zones under question, but these fossils need revision 

in this part of the stratigraphic sequence, as previously 

emphasized, and they cannot be seriously considered in 

their present status. The flora has been widely held to 

change to Tertiary type ~ith the passage from Fox 

o Bubnojf, S., Geologie von Europa, vol. 2, pt. 2, pp. 1007, 1017-1018, 

1935. - 1o Pia, Julius, Grundl.>egriffe der Stratigraphie, pt. A (especially pp, 

68-85 ), 1930 ( contains good bibliography). Schindewolf, 0., Probleme 

der Devon-Karbon Grenze: 16th Internat. GeoL Cong. Rept., vol. 1, 

pp. 505- 513, 1936. - 11 Bubnotl', S .. Grundprobleme der Geologie, pp, 120--136, Berlin, 1931. 12 Schindewolf, 0., Die Liegendgrenze des Karbons im Lichte bio- stratigraphischer Kritik: Cong. Strat. Carb., Heerlen, Compte Rendu, pp. 651-659, Liege, 1928. 
. LATE MESOZOIC AND EARLY Ci NOZOIC ~!STORY OF CENTRAL UTAH 147 

Hills to Lance and to continue unchanged in domin]at ment. If paleontologists d. isagree too various.ly as to 

aspect thr~ugh the Lance and · Fort Union, but rece1 t the significance of different groups of fossils, the probpaleobotanical study of the transition beds by Dor 13 lem becomes admittedly difficult, but in the present case ·a.nd Brown 14 has shown the older views on this tra i- there seems to be agreement as to the major part of the 

twnally moot subject to be erroneous. The floras of t~e evidence. The greatest change in total fossil assemLance and the Fort Union are evidently distinct. T e blage takes place at the poundary between the Lance 

mammals app'ear to change most sharply at the passa e and the Fort Union formations. At this horizon the 

from Lance to Fort Union, although Matthew/5 at lea . t, dinosaurs disappear, rand the placental mammals aphas argued that the Fort Union mammals should be e- pear. The Cannonball marine fauna, which occurs imgarded as Cretaceous ip type. This conclusion, it m st mediately beneath it, has been shown by Stanton 17 to -

be observed1 finds no evident support among vertebr te be dominantly Cretaceous in aspect, although it conpaleontologists of the present day. tains a number of species of Tertiary affinity that emAs a result of these and' other more detailed diff r- phasize its position near a logical boundary. The 

ence_s in change from Cretaceous to Tertiary types f changes that occ~r ~etween the panian and the .Montian 

fossil assemblage, at least three horizons have be n of Europe. are similar, and Euro~ean g~ologists have 

proposed to mark the boundary, namely, the Fox Hil s- b_een drawu~g the boundary at this _horiz:on for some 

Lance cont~ct (Maestrichtian-Danian bo~ndary in. t e trn~e. Despite a me!lsure· of uncertainty In the corre- Euro~ean time scale), the Lance-Fort Unwn· (Dania - lat10n ~et":een America and Europe, the apparent_ag~eeMontian boundary), and the Fort Union-Wasat h ment It;- circumstance lends strength to the prmCiple 

('I'hanetian-Sparnacian boundary). , as apphed to the American section. 

The attempt to place a division in this column n Of the two groups on which difference of opinion h~s 

the. basis of a single group of organisms does not yie d most strongly ce~tered, the flora and .the mammals, It 

satisfactory results. Schindewolf's case for the e- may clearly be said that present-day JUdgment affords 

phalopods in the Devonian-Carboniferous questi n support rather than rejection of the Lance-Fort Uni~:m 

~eems to be much clearer than any apparent possibili y boundary. T~e flora, as note_d above, may not conflict 

In the Cretaceous-Tertiary problem~ Schindewol 16 so . s~rongly with the other ~vi_dence as was thought by 

maintains that major subdivisions should be drawn n ea_rhe~ wor~ers, and even If It does, the phenor_nenon 

the basis of the group of organisms used to establi h . will be entirely expectable; the great changes In the 1 

the subsidiary stages. In the western American Upp r ~lant world ~ave occu~red, in general, at times different 

Cretaceous the fossils most widely effective as zo e fr?m th~e In _the animal ~orld. Further, th~ floral 

markers, if a single group is to be selected, are t e ev1den~e Is logrcally s:nbord!nate t? ~h.e f~unal, In that 

ammonites and, especially, the scaphites. The amm _ the entire scheme _of geologiC subdivision Is fundamennites did undergo an important change in the stra i- tally paleozoologiC; a colu!lln based ?n paleobotany 

graphic interval under question; they became extin t alone would have strongly different outlines. As to the 

and this important event might perhaps be argued ~ mammals, modern students agree _that the greatest 

a basis for drawing the line. The disappearance of a change comes at the Lanc~-Fort UniOn bo~1ndary; the 

group of organisms, however, is in itself a poor criteri 1 n Lance ~ammals are ~efinitely of Mesozoic type, the 

for either correlation or subdivision. Even if it we e Fort Unwn of CenozmC.18 

accepted as a valid criterion in the present case, t e It may be objected, as suggested above, that of the , boundary would falJ at the top of the Fox Hills, placi g various features of fossil occurrence usable in correlathe Lance, with its manifold Cretaceous affinities, n tion the ones here stressed, namel;r, the disappearance 

the Tertiary. Of cour~e, in the strict application f of the dinosaurs and the appearance of the pl'acental 

Schindewolf's principle this would make no differen e, mammals, are among the weakest. Either the first or 

but to the writer it seems that the uncertainty investi g the last appearance of a fossil group is likely to reprethe disappearance of a group of fossils in agiven stra i- "sent accident of preservation, of sedimentation, or of 

graphic section, considering the highly varied pos i- migration, and in any case if the phenomenon is sharply 

bilities of accident involved, militates against the pri - defined it probably reflects a gap in some phase of the 

ciple as a unique means of solving boundary problen s. record. Under the concept of evolution,the sudden first 

For the placement of a boundary in a given section it appearance of a fossil assemblage in any section implies 

might be adequate, but for correlation of the horiz n a lack of knowledge respecting its forerunners, which 

thus established with distant sections it is inferior o is hardlv a valid basis for either correlation or subdimore inclusive. methods. vi~ion: this m~tter has been ably stated by Renier.10 

If no single fossil group will serve, the only appare t Likewise,.the disappearance ~fa grour at any one -place 

alternative is to find the horizon at which the chan e bears no Inherently cogent time relatiOn to the disapin total aspect of the fossil assemblage is greatest, aid pearance at another .place. Th~ two events here. con- . thus to preserve, as well as may be, the concept f cerned, howeve~·, .a~~ ]Uxtarosed In the reco:d at widely 

distinction between typical Cretaceous and typical Te _ separated localities, and .wi~h the last marine ~auna of 

tiary. This may rule out some groups of organisms s Cretaceous aspect. Their Inherent weakness IS offset, 

a residual minority, for example, the flora, if the old r 

views respecting paleobotanic affinities are in any mea::;-

ure correct; but it involves the only type of method ln 

which the paleontologist finds strength in dealing wi}h 

his complex material, namely, the essentially statistic~!. 

Summation of all available evidence, with the chec s , 

and balances inherent in logical evaluation of the uni s 

gathered into the summary, seems a much strong r 

procedure in general than pinning all faith on one el -

13 Dorf, Erling, Helationship between floras of type Lance and Fort 

Union formations: Geol. Soc. America Bull., vol. 51, pp. 213-236, 1940. 14 Brown, R. W .. oral communication. 15 Matthew, W. D., op. cit. ' 16 Schindewolf, 0., op. cit., p. 655. 11 Stanton, T. W., and Vaughan, T. '\V .. The fauna o{ the Cannonball 

marine member of the Lance formation: U. S. Geol. Survey Prof. I'aper 

128. pp. 1-60. 1920. - 1s Simpson, G. G., 'l'hird contribution to the Fort Union fauna at Bear 

Creek, Mont.; Am. Mus. Novitates 345 (especially table at end), 1929; 

Glossary and correlation cha,rts of North American Tertiary mammalbearing formations: Am. Mus. Nat. Hist. Bull. 67, art. 3, pp. 83- 84, 1933. 19 Renier, A., discussion, in Jongmans, Cong .. Strat. Carb., Hecrlen, 

Compte Rendu, p. xxxiv, Liege~ 1928. 
148 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

to some extent at least, by this concurrence, and ·the 

probability that they give specious appearance o£ contemporaneity is greatly lessened. ' . It is interesting to observe that Pia 20 rejects the conclusion of Pfeffer 21 'that the Cretaceous-Tertiary 

boundary be defined by the extinction of the dinosaurs 

and the appearance of the placental mammals, on the 

grounds that a division must not be made in continental beds alone, but only in reference to a typical 

marine section. This argument fails to take account 

of the possibility, eminent in the present problem, that 

the time of greatest change, the logical level for a 

boundary, is not represented anywhere in the world by 

accessible beds other than those of continental origin. · The North American section probably contains a good 

deal in the Cretaceous-Tertiary transition that is not 

represented by accessible marine beds anywhere. If a 

boundary based on acceptable criteria happens to fall 

in such a section, it should be placed there. There is 

nothing intrinsically transcendental about the marine 

section to demand that important boundaries be restricted to it. The tendency to regard marine beds as 

the oniy possible standard, to the exclusion of poten- -tial values in many excellent continental successions, 

may"perhaps be carried too far. Correlation with marine sections, if such exist, is of course important, but 

to force a boundary into the marine section merely on 

the assumption of superiority in general criteria ie 

hardly reasonable. 

It must be . recognized that Pia's stricture on the 

placement of boundaries in continental sections is based 

on a fundamental philosophy somewhat different from 

the concepts so far considered here. In a later paper 22 

than the one above cited Pia has expounded more fully 

his views on the general subject of geologic chronology, 

and in particular has c[arified his 'stand as to the 

commanding qualifications of the marine section for 

the establishment of boundaries. His entire argument, 

set forth in the form of six theses, is too extensive to 

review here, but his most important postulates bear 

directly on the subject at hand and may not be passed 

without comment. To Pia all geologic time units are 

purely artificial; no attempt to set up "natural" divisions should be made. The time scale should be re- garded primarily as· a device of convenience. Restric:. 

tion of standard divisions to the marine section is 

an element in the quest for convenience; marine horizons are easier to recognize over wide areas. 

'Vith most of Pia's argument the writer agrees, but 

the prescription that all boundaries must be purely 

artificial seems to venture farther than necessary from ·the field of available knowledge. If a more or less 

natural basis for a given division can be found, it is 

surely supe:rior to an artificial one, or in any event one 

that rests on no better qualification than the mere 

possibility that geologists in general might be brought 

to accept it. As to the case in hand, there is, after all, 

typical Cretaceous, and there is. typical Tertiary; the 

two are qnite different. If between the two a horizon 

can be found that marks off something significant of 

the difference and at the same time meets other reasonable requirements, it ought to be more effective than -one based.merely on convenience and agreement. 

As far ·as convenience and efficiency are concerned, 

ther:e are considerations that argue superiority oi the 

continental sections here involved over any known alternative marine sections. In the first place, as to the 

available paleontologic evidence, it 'is a fact of signa] 

importance that the vertebrates have evolved more 

rapidly than the invertebrates, and where abundant 

are more delicate time markers, despite the greater difficulty, compared with the invertebrates, of allowing 

for migration and contemporaneous occurr~nce of different facies. The importance of the vertebrates 

throughout the column from the Upper Cretaceous on 

is too well known to require. further comment on this 

point. Second, full application of Pia's principles to 

the problem of the Cretaceous-Tertiary boundary 

would result in a decision rather more divergent from 

established usage than would seem wise or practical. 

As a result of the protracted withdrawal of the sea during late Cretaceous and early Tertiary times, a marine 

horizon adequately distributed and recognizable to meet 

the stipulates of convenience would fall well within 

divisions long accepted without question as either 

Cretaceous or Tertiary-in other words, the proposal 

of such a division would be revolutionary to an extent 

neither necessary nor practical. Further, the boundary 

here recommended possesses one very important attribute of convenience, namely simplicity of application in 

most parts of the world. Inasmuch as ·marine units that 

contain the boundary are lacking in so many of the great 

areas of Cretaceous and Tertiary sedimentation, the 

problem of drawing a line between the two is greatly 

simplified for much, if not most, of the world. 

· In final point, how4Ner, it must be observed that the 

very possibility of recognizing a line of greatest total 

change in the life succession sugg~sts weakness in the 

division thus made. Under supposedly normal conditions of evolution such a punctuation must mean ac:-

cident resulting in omission that could only fortuitously 

be simultaneous over the world . . If the theory of evolution postulating "critical periods" be accepted, explanation may be found in the quickened evolution of some 

groups, such as the mammals, and the concurrent devastation in others, such as the dinosaurs, that invested 

the close of the Mesozoic. But this theory is by no means 

demonstrated. Berry 23 has pointed out certain of its 

weaknesses, as well as other 1nisconceptions widely 

cherished in related fields. If the record is scanned 

without prejudice, as Berry recommends, as· many important changes in the living world are seen to have 

occurred within the accepted divisions of the time scale 

as near the boundaries. FQrthermore, the important 

changes that do appear in the boundary zones may be 

more apparent than real; to take as an example one of 

the changes important in the present question, the sudden appearance of the placental mammals does not certainly mean a sudden surge in mammalian evolution. 

At any place in the world where the Mesozoic mammals 

are followed immediately by the early Cenozoic, the 

placentals of the Cenozoic assemblage are newcomers, 

not related to the underlying Mesozoic marsupials; they 

are descendants of stocks for which we have no record 

and which.might just as well have undergone somewhere 

a long preliminary evolution as a sudden upsurge. The 

absence of known ancestral stock for so many important 

animal groups that appear suddenly, well developed, in 

the fossil succession should be more convincing than it 

seems to be of the incompleteness of the geologic record, 

20 Pia, Julius, Grundbegriffe der Stratigraphie, pt. A, p. 84, 1930. 21 Pfeffer, G., Die Frage der Grenzbestimmung zwischen Kreide untl 

Tertilir in zoogeographischer Betrachtung, .lena, 1921 (not seen). 22 Pia, J., Das Wesen der geologischen Chronologie: Cong. Strat. Carb., 

Heerlen, 1935, vQl. 2, pp. 857-902, 1937. 23 Berry, E. W., Shall we_ return to cataclysmal geology?: Am. Jour. 

Sci., vol. 17, pp. 1-12, 1929. . 
LATE MESOZOIC AND EARLY C[ NOZOIC HISTORY OK CENTRAL UTAH ' 149 

·and in recognition of this incompleteness it is impossi' lle cession of movements begin!ling not later than the e:<rly 

to sustain in theory any significant variation in the r~e Upper Cretaceous and contlmnng through the Tertiary 

of evolution. The boundary between Cretaceous a~d to the verge of the Qua.ternary; p~rhaps even later. _To 

Tertiary placed OJ?- the bas~s of any sort of pronounc'? m~ll.thi~ wh?le .successiOn Laramide wo~ld dest:oy the 

change in the fossil'successwn cannot escape real pos~I- distinctive significance of the name ~nd would gain none 

bility of fallacy, and it might perhap.s best be regard d of the ends,normally to be s<?ught In nom~nclature. It 

frankly as an arbitrary device, f9unded as far as possib e would seem more a pproprmte to restrict the ter!n 

on phenomena of natural significance but hardly e - "Laramide" to the group of movements that occurred In 

pressive of any comprehensive principle. the later part ~f the Up~er Cretac~ous and the early - part of the Tertiary, cer~ainly not gmng beyol!d .Eocene 

NATURE AND EXTENT OF OROGENIC MOVEMENTS time. For North America such reasonable limits now 

NOMENCLATURE 

During the part of geologic time covered by this pap r 

at least three orogenic movements took place. The tern 

orogenic movement is here used in the sense discuss d 

by Stille,24 to mean compressive disturbance productiye 

of folded and thrust structures. The first of the three 

movements definitely recognized in central Utah o~­ curred between the late Jurassic and the early Upp r 

Cretaceous, the second, between middle and late Mo -

tana times, and the third probably not long after t~e 

beginning of the Tertiary. Later disturbances, bo h 

orogenic and epeirogenic, affected the area, but they a e 

outside the scope of this paper. The second and thi d 

movements here described are definitely proved a d 

fixed within narrow stratigraphic limits by angular u~- · conformities; the first is not so demonstrated, but s 

almost certain to have occurred, as pointed out belo . The first two movements were profound and probab y 

widespread, whereas the third was confined in centrrl 

Utah to a fairly narrow bel~. _ 

The nomenclature of these orogenies merits some e~­

planatory mention. In referring to the various episod s · of the orogenic succession North American geologis s hav~ generally followed the scheme of nomenclatu:rre 

brought together by Blackwelder.25 More recentty 

Stille26 has proposed a world-wide scale which, by vi - tue of its greater areal scope and the increased volume f 

fact on which it is based, is much more elaborate. Stille's j

scheme is founded on the postulate of orogenic simurtaneity discussed in the foregoing part of this repor , and as to detail the validity of his groupings may pe - haps be questioned. Further, the lack of agreeme4t 

between recently discovered North American orogeni~s 

and the ones specified by Stille makes it impossible ~o 

adopt his nomenclature without somewhat problemat c 

alteration. Blackwelder's list was formulated before t e 

actual intricacy of orogenic succession in the Mesozo c 

and Cenozoic was known, and it presents a much mo e · discrete picture than is now possible. The increasin 

number of orogenic pulses recognized in the Nort 

American ·cordillera, not to consider the world as a 

whole, raises the question whether valid grouping ~s 

possible. There also appears the corollary questiop 

whether anything more comprehensive than local 

nomenclature is justified. I 

It is not proposed here to offer any general solutioh 

of these difficulties. However, it does seem possible ~o 

recognize a group of disturbances in late Cretaceous an~ 

early Tertiary times to which the long-established terrp 

Laramide may apply. Where the limits of this group 

should be drawn is not easy to specify. As originalljY 

applied, the term "Laramide" was meant to designate~ 

single gr:eat ~isturbance separating t~e Cretaceo . s 

from the Tertiary. The structures attributed to th s 

disturbance are now seen to have resulted from a su -

seem possible, but when the world-wide scale is contemplated, clarity of distinction disappear~. ~ov~ments 

now known in central Utah occupy gaps In Stille s scale 

and produce a fairly even spacing of orogenic pulses; 

the second of the three here described falls about midway between ihe late Subhercynian and the early Laramide of Stille's classification. It seems nevertheless· worth while to retain the name "Laramide" in the sense 

above suggested, at least until more comprehensive 

knowledge shall require some other procedure. . _ 

If the nan1e "Laramide" is retained, however, the 

equally long-establ!shed word "revolution" should be 

abandoned. It is not only inaccurate as a specific substantive but also misleading in its implication of general 

cataclysm that almost certainly never happened. The 

evidence for central Utah alone suffices to show that 

hio·h mountains have been formed without the sweeping ch~nges, either · geographic or biologic, that were 

formerly visualized as basis for use of the term 

"revolution." 

For the purposes of this discussion, then, the first 

orogeny in central Utah will be called the mid-Cretaceous, the second, the early Laramide,_ and the third 

pre-Flagstaff. The first is n~t yet correla~ed accurate~y 

enough with any of the widely recognized orogen1c 

epochs of western -North America to justify a special 

name. The second,· in terms of the foregoing discussion, may properly be called ·Laramide. In distinction 

from the strong Laramide movements 'that occurred 

later in the Rocky Mountains farther north, this disturbance is designated early Laramide; it is probably 

the earliest that could reasonably be assigned to the 

group. The third movement is not yet well enough 

correlated with outlying regions to justify other than a 

local name; although it clearly came within the limits 

of the Laramide group of movements, it is here simply 

referred to th~ local stratigraphic colum~. 

SCOPE OF DISCUSSION 

The following part of this report is devoted to general description of the three orogenic J1!0Vements, the 

evidence by which they are recognized, and their probable extent as apparent from comparison with other 

regions . . In the comparisons here made, evidence considered for other regions is restricted for the most part 

to angular unconformity between strata of known age, 

or other strong proof of orogenic dates in the folded 

belts themselves. No attempt is made to analyze the 

evidence in the undisturbed intermontane and plains 

districts, where disconformities in considerable variety 

are difficult to interpret, and, in present state of knowledge, too uncertain in significance to bear serious <!on24 Stille, Hans, Present tectonic state of the earth: Am. Assoc. Petroleum Geologists Bull., vol. 20, pp. 850-851, 1936. 25 Blackwelder, Eliot, The orogenic epochs of North America: Jour. 

Geology, vol. 22, p. 645 1914. 26 Stille, Hans, Grundfragen der vergleichenden Tektonik, 1924. 
150 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

sideration. Whereas disconformity of the type recognized in the nonfolded belts might signify orogeny, it 

might just as well record nothing more profound than 

a slight general uplift or simply a climatic change. On 

the other hand, a profound orogenic movement might 

leave no observable trace in sedimentary successions not 

far from the scene of strong folding; the early Laramide movement of central Utah produced no disconformity detectable by ordinary observation in the perfectly exposed sections of the Book Cliffs, and the preFlagstaff movement left no visible trace in sections only 

a few miles east of the folded belt. Data at present 

available on the disconformities in the late Cretaceousearly Tertiary succession are insufficient, in most cases, 

t<_? allow discrimination. 

MID-CRETACEOUS OROGENY 

In recent years geologists working in the ·eastern and 

southern parts of the Great Basin have been assigning 

the main folding and thrusting to the Laramide epoch,27 

in change from the earlier concept that all Great Basin 

folding was late Jurassic, or Nevadian. These assignments are all based on comparison with the folded belts 

to the east where Laramide folding dominates; sediments of the ages necessary to fix the times of folding 

in these ranges are generally lacking. The evidence now 

available for central Utah suggests that this region 

was penetrated by foldip.g earlier than Laramide; and 

there are facts for other areas that either point definitely toward the same conclusion or may be so interpreted. 

The rocks of the Indianola group in central Utah 

contain conglomerates, especially in the lower and upper 

parts, which are so coarse and contain so much Paleozoic limestone debris that a highland source nearby to 

the west is certain. The conglomerates are coarsest 

toward the west in the Gunnison Plateau and the Cedar 

Hills.28 They become finer eastward, very rapidly in 

the Wasatch Plateau, on the east front of which they 

are represented by the Mancos shale. Furthermore, they 

are very thick in the western belt; Schoff reports nearly 

15,000 feet for the Indianola group in the Cedar Hills, 

and in the Gunnison Plateau east of Levan the Indianola group is probably not less than 10,000 feet thick, 

with conglomerate scattered throughout but concentrated largely in the basal and upper parts. In the Gunnison Plateau (fig. 16), beds of the Indianola group 

rest without apparent angular discordance on the Arapien shale and it seems unlikely that the disturbance 

leading to the forn1ation of the conglomerates was 

stongly effective on the site of the present Wasatch 

Mountains. That there was a compressive disturbance 

seems almost . certain, especially when the Indianola 

conglomerates are compared with those of the Price 

River formation in the Thistle district, which overlap 

and abut on the truncated early Laramide folds in the 

steep front of the late Cretaceous mountains. The Price 

River and Indianola conglomerates are much alike; the 

source of the Price River boulder fans is evident, and it 

is not likely that the source of the Indianola materials 

was much different. In any event it is difficult to pic.-

ture, without folding or thrusting, a sharply bounded ·upheaval such as that necessary to produce the highland mass from which the Indianola was derived. The 

writer therefore postulates a . belt of strong folding not 

far west of the southern Wasatch Mountains. 

The possibility should also be considered that this 

earlier folding did penetrate the southern Wasatch 

Mountains. The only place so far seen in the western 

belt . wh_ere the Indianola-Arapien contact clearly appears to lack angular discordance is the locality in the 

Gunnison Plateau mentioned above, and there the Laramide and later deformations were not strong. _ The orelations in the base of Mount N ebo are obscure, and in the 

Indianola district they are difficult to interpret, although they easily permit the assumption of parallelism. 

In Salina Canyon, which is near the eastern limit of 

the Laramide folding, the contact is almost certainly 

conformable. Elsewhere the rocks have been too 

strongly deformed to permit certain conclusion. It is 

evident only that in the area as a whole there is no extensive angular discordance beneath the Indianola. 

However, some effects of pre-Indianola folding as far 

east as the southern yV asatch Mountains are possible, 

even if not pronounced. 

The age of this orogeny lies somewhere between the 

late Jurassic and the early Upper Cretaceous. The 

marine beds in the Indianola are above the basal conglomerates of the group, and it_ is impossible to assign 

a precise date. However, the whole mass of strata in 

the lower Indianola is definitely a unit, to all evident 

effect a consecutive response to the uplift, and-it seems 

most likely that the disturbance occurred at some time 

near the beginning of the Upper Cretaceous. , 

As to the possible extent of this movement, facts are 

available that suggest a rather long stretch on the 

eastern border of the Great Basin and to the north. 

Beginning in southern Nevada the Overton fanglomerate, originally classified as Miocene (?) ,

29 has recently 

been found to contain species of Tempskya and Microtaenia, fossil ferns that are known elsewhere in beds of 

early Upper Cretaceous age only. 30 The Overton is the 

oldest postorogenic sedimentary deposit in the Muddy 

Mountains,31 where it lies in angular unconformity on: 

folded and thrust Mesozoic rocks, the youngest of which 

aTe Jurassic in age; the folding, apparently limited in 

age between the Jurassic and the Miocene, was assigned 

by Longwell to the Laramide epoch. If the basal Overton is early Upper Cretaceous, however, this orogeny 

could not have been Laramide, and it may well have 

been the same as the pre-Indianola of central Utah. 

Passing on to the north, in the central Wasatch 

lVIountains the major deformation has been placed, in 

all recent geologic study known to the writer,32 in the 

Laramide epoch, the late Cretaceous, or the early Tertiary. The geologists of the Fortieth Parallel Survey, 

however, described conglomerates and sandstones of 

Upper Cretaceous age assigned to the Dakota and Colorado groups, in angular unconformity over strongly 

folded Carboniferous and early Mesozoic rocks, in two 

localities, east of Salt Lake City and near Weber River 

on Lost Creek.33 Because at many other localities the 

Cretaceous is apparently conformable on the Jurassic, 

and because in the district east of Salt Lake City the 

21 Nolan, T. B., The Gold Hill mining district, Utah: U. S. Geol. 

Survey Prof. Paper 177, pp. 63-64, 1935. Gilluly, James, Geology and ore deposits of the Stockton and Fairfield quadrangles, Utah : U. S. 

Geol. Survey Prof. Paper 173J p. 73, 1932. Longwell, C. R., Geology of the Muddy Mountains, Nev.: U. S. Geol. Survey Bull. 798, pp. 121-

123, 1928. Hewett, D. F., Geology and ore deposits of the Goodsprings quadrangle, Nev.: U. S. Geol. Survey Prof. Paper 162, pp. 54-55, 1931. 2s Schoff, S. L., Geology of the Cedar Hills, Utah (unpublished notes). 29 Longwell, C. R., The geology of the ·Muddy Mountains, Nev.: U. S. 

Geol. Survey Bull. 798, pp. 89-90, 1928. ~o Hewett, D. Ji~ •• and others, Mineral Resources of the region around 

Boulder Dam: U. S. Geol. Survey Bull. 871, pp. 121-122, 1936. 31 Longwell, C. R., op. cit., pp. 68-74. / 32 For summary and bibliography see Beeson, J. J., Mining districts 

and their relations to structural geology: Am. Inst. Min. Met. Eng. Trans., vol. 75, pp. 768-79-2, 1927. aa King, Clarence, U. S. Geol. Expl. 40th Par. Rept., vol. 1, p. 304, 1878. 

Emmons, S. F., The Wasatch Range, U. S. Geol. Expl. 40th Par. Rept., 

vol. 2, pp. 38!-383, 391, 1877. 
LATE MESOZOIC AND EARLY CE OZOIC HISTORY OF' CENTRAL UTAH 151 

relations are somewhat obscure, King and Emmo s 

offered their account with strong reservations. Thei 

findings, however, are evidently valid. Mathews co~ roborated them in 1931, but his account contains no su - gestion of the importance of the phenomenon in t e 

regional geologic history.34 Other geologists appear t

1 have overlooked the older reports, possibly exceptin~ 

Beeson,35 who, in a tabular summary of geologic histor , indicated mild compression between Jurassic and Cr - "taceous, but did not discuss the matter. Eardley 6 

specified in a tabular outline of geologic history for th 

southern Wasatch Mountains "crustal disturbanc 

* * * probably beginning of ~aramide Revolutio~ ' at the beginning of Colorado time, but did not discu~s the point and gave neither evidence nor citation of a~­ thority. Thus, the possibility of important folding in 

the central Wasatch Mountains at some time betweet 

the late Jurassic and the early Upp.er Cretaceous ha 

been overlooked or slighted by most students of th 

region ; the evidence here reviewed makes such foldin~1 

appear highly probable. 

The foregoing should not be interpreted to mea 

that the central Wasatch Mountains underwent np 

Laramide deformation. In all parts of the range 

where Cretaceous rocks of Colorado age are prese~~ they are deformed, and in the southern part the Lar«jmide movement was obviously the strong one. In the 

central and northern districts, however, the olde!1 

movement may have been equally strong or stronger; 

the Cretaceous ( ? ) rocks of the Salt Lake-Lost Cree 

district are by no means so profoundly deformed a 

were the Jurassic and older rocks before them. 

It might be noted, as regards the date of this orogen 

in the central Wasatch Mountains, that in the Coalville 

district the conglomerates of Colorado age 37 lie in th~ 

rpiddle part of the stratigraphic interval characterize<?.; 

by the Carlile fauna, 38 equivalent to the upper part o 

the Benton in the standard section of the Great Plain . To interpret this occurrence in the present state o , knowledge is admittedly somewhat precarious. It doe · suggest, however, the culmination of an orogenic puis 

in early Colorado tin1e. 

Still farther north, in the mountains of souther 

Idaho,. the earliest fol?ing cam~ before the depositiof 

of the Wayan formatiOn, described by Mansfield 39 af 

nearly 12,000 feet thick and assigned by him with doub! 

to the Lower Cretaceous. The Wayan formation i 

now assigned to the lJpper Cretaceous ;

40 it contain 

T emp8kya, among other things, and is at least in par 

equivalent to the Bear River formation of southwester 

\Vyoming. As described, the Wayan lithology strong! 

suggests Indianola, and the new age assignment adds 

to the probability that. the two are at least partly equiva 

lent. In Mansfield's sections the Wayan is shown i 

angular unconformity over older folded rocks. Thi 

movement demonstrated for southeastern Idaho rna 

have been the same as the pre-Indianola of central Uta . It should be noted, in connection 'Y"ith . these occur 

rences, that the determination of Laramide folding fo 

the Tintic Mountains 41 and the Canyon Range,42 nea 

the eastern margin of the Great Basin, rests on the 

identification of post-orogenic conglomerates in thes~ 

areas as Wasatch in age. These conglomerates ar 

similar in all respects to the Indianola and Price Rive -conglomerates of the Wasatch Plateau, which were orig 

inally identified as Wasatch, and they may well be I 

part of early Upper Cretaceous age. The same is tru 

of the great masses of conglomerate in the Pavan 

Mountains 43 and elsewhere in the general region. Re- · 

connaissance examination of these. occurrences has impressed the writer strongly ~ith the possibility that 

these conglomerates include Indianola and perhaps also 

Price River strata. 

These facts suggest that in the broadly arcuate belt 

between southern Nevada and southeastern Idaho, 

:whose eastern margin is shown on figure 20, there was 

FIGURE 20.-Map of western part of United States showing probable eastern margin of mid-Cretaceous folding. 1, Muddy Mountains; 2, areas west of Wasatch Plateau; 3, central Wasatch 'Mountains; 4, r_anges of southwestern Idaho. 

strong orogeny at some time near the beginning of the 

Upper Cretaceous. Farther north in the Rocky Mountains there is no evidence of such movement, and in 

western Montana there is positive proof of its absence; 

Calkins and Emmons 44 have described black marine 

shale of Colorado age overlying the Kootenai formation with no sign of angular discordance, in the Phillipsburg district, ~fontana, well behind the front range 

ii1 the heart of the Rockies. The folding either died out 

north of southern Idaho or veered northwestward. The 

strong north west trend of the folds in the northern part 

of the area described by Mansfield 45 suggests the latter 

34 Mathews, A. A. L., Mesozoic stratigraphy of the central Wasatch 

Mountains; Oberlin College Lab. Bull., new ser., vol. 1, pp. 48-50, 1931. 36 Beeson, J. J., op. cit., p. 765. 36 Eardley, A. J., Structure and physiography o.f the southern Wasatch 

Mountains : Mich. Acad. Sci. Papers, vol. 19, p. 398, 1934. 37 Wegemann, C. H., The Coalville coal field, Utah: U. S. Geol. Survey 

Bull. 581, p. 112, 1915. · .· as Reeside, J. B.,· Jr., Upper Cretaceous and Tertiary formations of the western part of the San Juan Basin, Colo. and N. Mex .. : U. S. Geol. 

Survey Prof. Paper 134, p. 10, pl. 3, 1924: In Gregory, H. E., and 

Moore, R. C., The Kaiparowits region: U. S. Geol. Survey Prof. Paper 

164, p. 113, 1931. 39 Mansfield, G. R., Geography, geology, and mineral resources of part of southeastern Idaho : U. S. Geol. Survey Prof. Paper 152, pp. 105-108, 

195, pls. 5, 11. 1927. 40 Read, C. B., and Brown, R. W., American Cretaceous ferns of the 

genus Tempskya: U. S. Geol. Survey Prof. Paper 186-F, 1937. 41 Lindgren, Waldemar, and Loughlin, G. F., Geology and ore deposits of the Tintic mining district, Utah: U. S. Geol. Survey Prof. Paper 107, 

pp. 103-104, 1919 . . 42 Loughlin, G. F., A reconnaissance of the Canyon Range, west-central 

Utah: U. S. Geol. Survey Prof. Paper 90~ pp. 53-58, 1914. 43 Richardson, G. B., Underground water in Sanpete and central Sevier 

Valleys, Utah: U. S. Geol. Survey ·Water-Supply Paper 199, p. 10, 1907. 44 Calkins, F. C., and Emmons, \V. H., U. S. Geol. Survey Geol. Atlas, 

Phillipsburg Folio (No. 196), p. 9, 1915. 45 Mansfield, G. R., op. cit., p. 131. 
152 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1 9 4 3-4 5 

alter~ative; the mountain front of early Upper Cretaceous time probably curved around in a sweeping arc 

through southeastern and central Idaho into the region 

no'Y covered by the lavas of the Columbia Plateau. 

This trend may possibly ~oin the lineaments of east and 

southeast-trending folds In the Pacific districts 46 where 

some evidence of mid -Cretaceous folding 47 has 'been reported, but the dates of the movements are poorly define4 in .these western mountains, and the transverse 

folding In the Cascade Mountains seems to be older 

than Jurassic. Furthermore, there seem to be no known 

facts on which ·to premise n1id-Cretaceous folding in e~s~~rn Oregon,48 but for future investigators the posSibility may be well worth holding in mind. 

The foregoing discussion should not be construed as 

argument that the orogeny involved comprised a single 

episode, contemporaneous in all the districts cited, nor 

even that it was co~cen~rated in OJ?.e e.pisode at any one 

place. Th.e orogenic disturbance IndiCated by the evidence .revi~wed ~3:Y hav~ been sep.arated, like the 

Lara!llide, Into distinct episodes of different intensity 

at different places. Indeed, the evidence in central 

Utah strongly suggests more than one movement· the 

congl?merates in the upper part of the Indianola g~oup n1ay In some respects be most logically interpreted as 

the result of a distinct orogenic disturbance, later than 'the one that gave rise to the lower conglomerates of the ~nd~anola.. This possibility is important enough to · JUStify bnef comment as a final point respecting the 

mid-Cretaceous disturbance. 

As now known, Inost of the evidence for the midCretaceous orogeny affords no basis for postulating 

more than one movement at any given place. In central 

ptah, how~ver, the distri?uti.on of coarse conglomerates 

In. the Indianola group Is difficult to visualize as anything b~t the result o.f two movements separated by a 

notable Interval of quiet. In the Cedar Hills the Gunnison Plateau, and the western border of th~ Wasatch 

Plateau. there are cong~om~rates in the upper part of 

the Indianola group whiCh In general are just as coarse 

and prominent as those in the lower part. In the Cedar 

Hills and the Gunnison Plateau the conglomerates are 

scattered through the Indianola in a manner that 

might easily be interpreted as the result of protracted 

orogeny, perhaps .with a culmi_nat~ng s~rge toward the 

end. In the sectiOn of the Sixmile district however 

the Sixmile Canyon formation contains conglomerate~ that are separated trom those of the Sanpete formation 

by about 2,500 feet of finer sediments. In this district 

the Sixmile Canyon conglomerates are more promi- · nent than t~ose of th~ Sanpete. These upper masses of , coarse d~bris must, hke the lower, have been derived 

!rom a h~gh land mass not far away, and, if the reasonIng apphed to the lower conglomerates is consistently 

follo":ed, the uplift of. thi~ land mass is most likely to _have Involved orogenic disturbance. The finer sediments of the Allen Valley and Funk Valley beds are 

present at the northern and southern ends of the border b~lt ·?f the Wasatch Plateau, as well as in the Sixmile 

district, and they are evidently extensive in this gener!ll belt flanking ~he ancient highlands. They certainly ~eprese)lt a; time when little or no coarse debris w~s ~mng s~ept I~to the basin of deposition. In the ~XI~tlng se~tlng, th.Is w~uld normally be interpreted to 

IndiCate diastroph~c quiescence a:nd the slow wearing d~wn of reduced ~nghlands remaining from the initial 

mid -Cretaceous disturbance. - Other facts for regions 

to north and south of the Wasatch Plateau; as far away 

as the Coalville district and the Kolob Plateau, tend to 

support this general picture. , The mid-Cretaceous orogeny, then, appears· to have 

comprised two separate pulses in central Utah. The 

evidence for this duality, however, is probably not complete ~nough to justify a definite commitment, and in 

summing up the orogenic history of the region it is 

perhaps wise to designate the second movement as 

probable but not positively demonstrated. 

EARLY LARAMIDE OR-OGENY 

The early Laramide orogenic episode is recorded in 

the strongly folded strata of the southern Wasatch 

Mountains and in the continuation of that folded belt south~ard through Sanpete and Sevier Valleys, the 

Gunnison Plateau, and the western border of the 

Wasatch Plateau. The area affected by this movement 

doubtless extends far westward into the Great Basin, 

into territory not yet studied in detail. In the Wasatch 

range proper the folded rocks rise high above the surrounding territory and form the main mass of the mountains, but in the districts to the south and east they were 

planed off by erosion immediately after the folding, 

and: they are for the ~ost ~art buried under postorogenic 

sediments of the Pnce River and later formations, in 

pronounced angular unconformity. The eastern margin of the folded belt follows rather closely the trend 

of the eastern _borders of Sanpete and Sevier Valleys 

and penetrates Into the vVasatch Plateau in the northern 

part between Thistle and Indianola, and in the southern 

part between Manti and Salina. 

The folding is dated between middle and late Montana times by the angular unconformity and the regional 

relations of the strata involved; these phenomena are 

described sufficiently for the purposes of the present report in the fore~oing ac?otmt of the stratig;r~phy. The an~ular un~onform~ty _Is locally very striking in the · Thistle-Indianola district. (See pls. ·21, B, and 24 .A.) 

Along the east front of the southern Wasatch Mountains. it is also pro~ine~1t,_ as described by Eardley,49 

and In the Cedar Hills It Is well developed and widespread, as found by Schoff.50 It is also exposed· on the 

east front of the Gunnison Plateau near vVales (pl. 24 

B), and in Sixmile Canyon (pl. 25, A, and fig. 17). At 

all these places the beds above the nonconformity are 

either Price River or North Horn. At the Wales and 

Hjork Creek localities there is evidence of later disturbance, which occurred after the period of time covered_ b~ this report.. (See pls .. 21, B, and 24, B.) East 

of Indianola and In the Sahna Canyon district (pl. 

25, B) the older folded rocks are overlain by the Flagstaff limestone, and here they were pro.bably affected 

by the pre-Flagstaff movement, although these. occurrences may merely constitute areas that remained high 

long after the early Laramide movement and were not 

covered by sediments until Flagstaff time. Where the 

~~tervening seditt:ents a~e not clearly present, it is 

drfficult to recognize the separate effects of successive 

movements. 

46 Gilluly, James, Reed, J. C., and Park, D. F., Jr., Some mining districts of eastern Oregon: U. S. Geol. Survey Bull. 846-A, p. 20, 1933. 

Waters, A. C., Transverse folding, Cascade Range: Geol. Soc. America 

Proc. 1935, p. 116 (abstract), 1936. 47 Blackwelder, Eliot, The orogenic epochs of North America: Jour. 

Geology, vol. 22, pp. 645-646; 1914. 48 Lupher, R. L., personal communication. 49 Eardley, A. J., Structure and physiography of the southern Wasatch 

Mount!lins : Michigan Acad. Sci. Papers, vol. 19, p. 398, 1934 : Stratigraphy of the southern Wasatch Mountains: Michigan Acad. Sci. 

Papers, vol. 18, p. 334, 1932. GO Schoff, S. L., Geology of the Cedar Hills, Utah (unpublished notes). 
. -I' · - LATE MESOZOIC AND EARLY CfNOZOIC HISTORY OF CENTRAL UTAH 153 

.As a whole, the eviden?e from 'Yhich the early L~ a- sionally with the Knight o'r the. Almy formation of _ 

mide orogeny has .be.en dis?er·n. ed Is ver.y clear, perha s . southw __ estern Wyom. ing,53 . recognizing . no d-istinction- as clear as such evidence might ever be. _. between the two in Idaho and expressing doubt that they · 

. T~1e d~te now ascertained for the strong Larami e are separable in the type area. As pointed out on p. 

fo~di_ng In central. Utah is the e~rliest on record for 138, the Knight contains the Wasatch fauna, but the 

t~Is Imi?ortant-senes of late Cretaceous and early T~r- 4-lmy is not accurately dated at the type locality; in the 

tiary disturbances, and the question naturally ari es · hght of. the writer's field observations it is distinct from 

whether.the movement was merely local. The gene al · the Kmght and prol?ably much older. Therefore the 

abse?ce 111 the yor~illeran regio~ of evidence even s g- tlge of the fold~ng and thn~sting in southeastern Idaho 

gest1_v~ of fold1?g 1~ Montana time would tend to .t e ca~not be preCisely ascertained. In southwestern Wysusp.ICwn that It might hav:e been neither wides-pre d oming Veatch 54 placed the main Laramide disturbance 

nor Impo~tant. When carefully reviewed, however t is between the Adaville formation, probably of late Monlack <;d evidence is seen to be of essentially neutral v'al e tana age, 5

5 and the Evanston formation, probably of 

and In none_ of the known _mountain districts do t ~ Fort Union age. Schultz 56 drew. the same conclusions 

facts exclude possibility of fate Montana folding. for t~e mountain front to the no~th, east of the area 

T~e early Laramide folding nas been definitely r c- descnbed by Mansfiel~. The re~atw:r:s of ~he late Creognized as far north on the east front of the. w asat h tace\ms and early Tertiary rocks In this region, however, 

Mountains as the district surrounding Thistle. The Jx- studied recently by Rubey/ 7 are more complicated than 

tent to which it was effective in the ranges farther no~th Schultz thought the!? to be. ~ . . cannot be specified until ~he ages of the postorogel]l.ic Although the precis.e ages of ,the-Laramide movements 

conglomerates of that regwn, hitherto generally des g- have not been ~eternnned, the co~for~ab~e Upper Crenated as ~oce:p.e, are certainly known. _The thl.ekn ss tac~ous stra~a I~ western Wyoming IndiCate that the 

and prominence of the conglomerate in the Price Ri er main thrusting: 1S of late Montana or younger, age and 

for1nation i~ th~ Thistle district, as well as the in tens. ty theref~re that It occurred at a date later tha~ the early 

of t~e folding In the rocks beneath it, easily sugg st Lararn.I_de .moven;ent. o! .central Utah. · Ayailable eviconsiderable northward extension of the movement. It ~enc~ admits the possibility of early Laramide deformais likely, co?sidering all the regional evidence, that he ~Ion In southeaster? Idaho th~t did not affect .the rocks 

postorogenic copglomerates in the central Wasa~h In western Wyon~Ing ~ast. of ~he , Was~tch lineament. 

Mountains are in p~rt of Price River age, althou )·h . In fa~t, the Coal':'Il1e distnc.t ~f no_rther~ Utah 58 shows 

some, as already pmnted out, are almost certainly of a sectwn, arched Into.an anhchne, In whiCh there are no 

Colorado age. In these mountains, between Provo· a ld angular br~a~s as ~Igh ~s the co~glomerate of Echo 

Weber ~ivers, roc~s of Upper Gretaceous age are 11 _ Can:yon,. onginally Identified a.s basal Wasatch but, as 

volved Ill the folding, but the age of the youngest d'S- stu,died Ill the field by the Writer, probably older, _alturbed beds is ri?t known; in the main range of ' he though cle~rly not older than late Montana. The con-

\Vasatch Mounta1ns no rocks of late Montana age he ve glo~erate Itself bespeaks orogeny not far to . the west, 

been reported. Farther east, in the Coalville distr· ct possibly contemporaneous With the early Laramide 

and other bor~er belts. of the Uinta ~fountains, he _mov.ement of central Utah. · . strata of Mont~na a~e give no clear evidence of oroge y. Farther north, betw~en northe!n '\Vyonung _ and 

If early Lar.am~de disturbance occurred in this latitu le, sou.thern Canada, a maximal t~rusbng, or ~t~ least that · apparently It did not penetrate as far east as the Co l- which penet~ated farthest plainsward, occurred after 

ville distric~. For many miles around Coalville, hofv- the Fort Uni?n .. 

59 

.An~ular unconfo~mity ).~roving an 

ever~ t~ere Is a complex of conglomerates; yet Iarg ly upper :;tge limit lS ~enerally lacking. Ihe Heart 

U:!!-studied, that may contail). the equivalent ()f the Pr ee lVloun~ain thrust, de~nitely pl3:ced by Hewett 60 between 

River formation .. This whole area east of the cent ·al the middle Eocene and th~1 Ohgocen~, app~ars to be an 

'Vasatch Mountains ~as affected by disturbances la er u~usual typ~ . of struc~ure and possibly not connected 

- t~an the early Lara;mide, some later than the period of with the .main Lara~ude o:ro.geny. In the western p~rt time covered by this report, and careful study will be of the Bighorn Basin there Is an ang.u_lar uncon~ornnty 

necessary before the orogenic succession cmi be l· id between62the ~ance and the ~ort Unwn, ·descnbed by 

out with any assurance. -- To sum up for the cent 'al Hewe.tt an~ Interpreted by him to represent mild, local 

Wasatch Mountains, it seems that the early Laram'de · warping; this appears to be the, only Instance on record 

orogeny may well have affected the area, although c 11 _ o~ angular ~rea~ between these two units. In this revincing evidence is yet lacking. gwn the m~u~ disturbance.appe~rs to have occurred beFarther north, the Bannock overthrust of southea tern Idaho ha~ ?ee~ interpreted by _Mansfield 51 to rep esent the culmination of Laramide movement in t at 

~art of the _Cordi1lera. This thrusting occurred at so~1 e 

time between the deposition of the Wayan formation 

and that of a co~glomerate ~,ssigned by Manffield to he 

Wasat.chformatwn. As pmnted 011t in the discussion of 

the mid-Creta~eous orogeny, the youngest beds in he 

W aya~ formatwn are now known to be of Colorado age. 

The evidence on which the postorogenic conglorrierat~Pis 

place~ as '\Vasatch is similar to that from central U ah 

on which the conglomerates of the Price River formation 

i~ the western '\Vasatch Plateau were originall¥ id ntJfied as Wasat~h, and the conglomerate in Idaho ay 

not be Eocene In age. Mansfield 52 ~dentified it pro i-

:~Mansfield, G. R., op. cit., pp. 169-170, 198-199. 

Mansfield, G. R., op. cit., p. 109. 63 V~atch, A. C., Geography and geology of a portion of southwestern 

WyoJpmg: U. S. Geol. Survey Prof. Paper 56, pp. 88-96 1907. 54 Veatch., A. C., op. cit., pp. 7G, 76. ' •

55 Ree~ide, J. B., Jr., in Gregory, H. E., and Moore, R. C., 'l'he Kaiparo- WI~0s regiOn: U. S. Geo~. Survey Prof. Paper 164, p. 113, 1931. 

Schultz, A. R.. Geology and geography of a portion of Lincoln 

County, Wyo. : U. S. Geol. Survey Bull. 543, p. 77, pis. 1, 3, 1914. 57 Rubey, W. ,V., personal communication. 58 Wegemann, C. H., 'l'he Coalville coal field, Utah: U. S. Geol. Survey Bull. 581, pp. 162-171, 1915. su Bevan, Arthur, Geology of the Beartooth Mountains: Jour. Geology. 

vol. 31, p. 454, 1923. Russell, L. S., Cretaceous-Tertiary transition of Al~erta: R9y. Soc. 9,anada Trans., 3d ser., vol. 26, pp. 150-15).. 1932. '> Hewett, D. F., Ihe Heatt Mountain overthrust: Jour. Geology, vol. 

-8. pp. 536-558, 1920. _61 Bucher,. W. H., and ot hers, (}eologic problems of the BeartoothBig-horn regiOn: GeoL So . America BulL, vol. 45, pp. 176-177, 1934; 

Bucher, W. H., Remarkabl local folding, possibly due·to grl!vity bearin"' on the Heart Mountain t rust problem [abstract] : Geol. Soc. '.Americ~ Proc. 1935, p. 69, 1936 • . 62 .Hewett, D. F ., Geolo y and oil a!ld coal reRources of the Oregon · Basm, l\feeteetse, and Gra s Creek Basm quadrangles, Wyo.: U. S. Geol 

Survey Pro-f. Paper 145, p ). 35-36, 1926. · 

I _ 
.. 

...... 

154 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

tween the Fort :Union and the Wasatch, possibly the 

same as the Lewis thrust movement at the north. It is 

interesting to observe, however, that recent studies in ~askatchewan '

63 reveal a notable pre-Lance disconformIty, as well as a stronger one between the Fort Union 

and the Wasatch. 

None of thi.s northern territory affOTds proof of strong 

early Laramide movement . . Recently, however, Wilson 64 has interpreted the Judith River sediments northeast of the Beartooth Mountain in southwestern Montana to indicate the beginning of Laramide orogeny 

there. The .evidence adduced by Wilson clearly signifies changes In the source land to the1

west, and even if it · does not prove actual folding, it is at least highly suggestive in light of the determination for central Utah. 

It is important to keep in mind that the data available 

for the Rocky Mountains of Montana and Wyoming in 

general do not prove absence of orogeny in Montana 

time; they show only that any movement so early did 

not penetrate as far eastward as did the post-Fort 

Uni<?I1 movement, and, to judge by such fen,tures as the 

Lewis overthrust, was·not so powerful. The possibility 

of early Laramide folding in this region seems perfectly 

c!ear, and, in .terms of Wilson's interpretation, rather 

hkely. 

East of central Utah lies the Telatively inert Colorado 

Plateau, which was not strongly penetrated by the intense folding of surrounding parts of Utah and Colorado. It was deformed, however, into the gigantic monoclines and swells early made classic by Powell, Dutton, 

and Gilbert, in a movement generally ascribed to the 

Laramide disturbance,65 dated with respect to beds assigned to the Wasatch fO'rmation that may be the same 

as the Price River and North Horn formations of central Utah. These structures may therefore belong in · ti:~ early epoch of folding, but to the writer the possibihty seems stronger that they were formed at the time 

of the pre-Flagstaff movement, as is pointed out farther 

on. 

North of the Colorado Plateau lie the cross-trending 

Uinta !\fountains, whose structural relation to the northtrending ranges faTther west is still an open question, 66 

as is also the date of the earliest folding. Those students . of the range who have committed themselves place the 

folding at the end of the Cretaceous. The most recent 

contribution, by Forrester ,

67 presents an analysis of the 

structure in which two epochs of disturbance are recognized, the fiTst of which is dated at the close of the Cretaceous and held to be simultaneous with the main folding in the Wasatch range. The stratigraphic basis for 

the age assignment, however, is not well established, and 

the structural arguments are not conclusive.68 · The initial Uinta folding may possibly have occurred at the 

e?-d of the Cretaceous, but it could hardly have been ~1mu~taneous with that of the Wasatch Mountains; this 

IS evident from data already pTesented in this paper, 

and there are many facts in the central Wasatch-Uinta 

mountain region that point toward the same conclusion. 

For one thing, purely structural evidence in the Wasatch 

Mountains indicates diffef'ence in time of folding. 

Calkins 69 and others have shown that structural features of the Wasatch lineam(}nt are penetrated by intrusive masses allied with the Uinta arch.; it seems clear 

that at least the .intru~ional phase of the Uinta disturbance was later than the Wasatch folding, but this phase 

may have ocQurred ·in the second epoch recognized by 

Forrester. That the initial Uinta folding was later 

than that of theW asatch Mountains is further suggested 

by known conditions farther east in the Uinta Tange, 

where rocks much younger than the Price River formation of central Utah are involved in the folding. On 

the north flank of the main range precise stratigraphic 

evidence is lacking. On the south flank the youngest 

strata involved in the folding have been identified as 

the Mesaverde formation, of Montana age, whereas the 

Tertiary beds of the Uinta Basin overlap the Cretaceous and older formations; th~ basal part of the Ter.:. 

tiary section has been identified as t,he Wasatch formation.70 Reconnaissance examination has convinced the · writer that the identification of the Wasatch formation 

is wrong in some places, as in the vernal district, and is 

open to doubt elsewhere. The identification of the 

youngest strata in the folded series as. Mesaverde is 

likewise open to question; as seen by the writer on Duchesne River below Hanna, these strata resemble 

• strongly the later Cretaceous of areas to the southwest, 

and ·this adds to the suggestion of folding later than 

Montana. Furthermore, although the stTata of the 

Uinta Basin overlap the Cretaceoas formations, the contact is by no means sharply angular in the eastern part 

of the range, and beds as high as the Uinta formation, 

of late Eocene age, are tilted as strongly, or almost so, 

as the Cretaceous.71 This condition is also evident in 

the eastern prolongation of the Uinta axis, in northwestern Colorado, where in general there is no angular 

break in the column as high as the Green River formation.72 On Vermillion · Creek, however, Sears 73 has 

rna pped the Wasatch formation in angular unconformity over tilted Mesozoic and Paleozoic rocks, and for the 

eastern end of the Uintas, on the north flank, Schultz 

has shown similar relations on his map· and sections, 

without discussing them.74 It is not certain that this 

formation is wasatch in age, although the likelihood 

appears stTonger than at other places discussed in this 

paper, because in the territory east of Vermillion Creek, 

north of the Uinta axis, there is a rather complete section in which the Lance and Fort Union are probably · represented by the LaTamie and po'st-Laramie of former 

usage.75 These beds are overlain by strata assigned to 

the Wasatch. In this section, although there is no angular unconformity, a strong disconformity overlain 

by the basal conglomerate of the so-called post-Laramie 

"formation suggests the initiation of folding in territoTy 

nearer to the mountajns between Lance and Fort Union 

times. 

-----1 63 Fraser, McLearn, and others, Geology of southern Saskatchewan: 

Geol. Survey Canada Mem. 1 "1:6, 1935. . 64 Wilson, C. W., Jr., Geology of Nye-Bowler lineament, Stillwater and 

Carbon Counties, Mont.: Am. A~soc. Petroleum Geologists Bull., vol. 20, p. 1185, 1936. . . 65 Baker, A. A., Geologic structure of southeastern Utah: Am. Assoc. 

Petroleum Geologists Bull., vol. 19, pp. 1472-1507, 1935. 66 Gilluly, James, op. cit., pp. 71-73. 67 Forrester, J. D., Structure of the Uinta Mountains: Geol. Soc. 

America Bull., vol. 48, pp. 631-666, 1937 . . 68 Spieker, E. M., Comment on paper by J. D. Forrester: Geol. Soc. 

America Bull., vol. 48, pp. 2037-2043, 1938. 611 Calkins, F. C., in Butler, B. S., and others, '.rhe ore deposits of 

Utah: U. S. Geol. Survey Prof. Paper 111, pp. 251-254, 1920. 70 Lupton, C. '1'., The Deep Creek district .of the Vernal coal field, 

Uinta County, Utah; '.rhe Blacktail (Tabby) Mountain coal field, 

Wasatch County, Utah: U. S. Geol. Survey Bull. 471, pp. 585, 607-608, 

1912. Forrester, J. D., op. cit. 71 Spieker, E. M. , Bituminous sandstone near Vernal, Utah: U. S. 

Geol. Survey Bull. 822, pp. 80-82, 1930. 72 Gale, H. S., Coal fields of northwestern Colorado and northeastern P~t8.: U. S. ol. Survey Bull. 415, pp. 40-44, 72-'86 (especially p. 84), 

73 Sears, J. D., Geology and oil and gas prospects of part of Moffat 

County, Colo., and southern Sweetwater County, Wyo.: U.S. Geol. Survey Bull. 751, pp. 291-293, pl. 35, 1924. 74 Schultz, A. R., Oil possibilities in and around Baxter Basin, in the 

Rock Springs uplift, Sweetwater County, Wyo.: U. S. Geol. Survey 

Bull. 702, pls. 1, 10, 1920. 15 Reeside, J. B., Jr., personal communication. 
LATE MESOZOIC AND EARLY f E'NOZOIC HISTORY OF UTAH 

In gener~l, then, the evidence seems to show that the more deSirable, ~ut it 'is tJJ:e .;,riter's judgment, in esti155 

orogenic history of the Uinta Mountains began nota~ly mate of the regwn l stratigraphy, th~t th.e movement 

_later than tha.t of the Wasatch Mountains. ~he· cen~ral took pl~ce bef~re t ~close of Fort Unwn ti~e. _ 

part of the Uinta arch may have begun to rise near~he It Is Interestmg t compare the known-outlines of the 

close' of the Cretaceous,_ but the _e_ ast. ern ext-ension. .o~ . he central Utah fold. \vith- monocline. s gf _tlie Colorad. o 

axis was nc;>t strongly d~sturl;>ed before the ~~pos:t on Plateau in souther and .easter!l Utah. Altho~gh tl_le 

of the Green River formatiOn, probably Ill -mi le . west flank of the old IS buned beneath allUVIUm Ill 

Eocene time. - · . · Sanpete and· Sevie Valle:ys, exposures of- ~he North 

Farther east and south in the Colorado Rocl;nes, I he Horn and .Flagsta formations on the w_est sides .. of the 

Upper Cretaceous rocks' appear to show: no sign · of va_ll~ys and adjac nt highlands suggest that It was 

disturbance-comparable to the ea~ly Laramide of cen ~al ongmally gentler t an .the eas~ flank, and that the ~old 

Utah. There is no need to review here the exten IVe - was the sort of mo ochne typified by the East Kaibab 

literature on that area; interpretations might perh ps and Waterpocket ~x~res of southern Uta~~ These 

be inade of some sections to suggest Upper Cretace us structures have be n Interpret~d by Baker . as. the 

disturbance, but in the present state of knowledge t ey result of deep-seat d compressive fo_rces, whiC~ p-rowould be necessarily inconclusive. The disturba ce duced steep overthr sts in the underlying basement and 

recorded- by the c~mglome:ate at the I;>ase of ~he Ara ~- died out upward, and :which are repre~ented, at the 

hqe formation, discussed In a foregmng sectiOn of ~Is present surface by he strongly asy~met~ICal. upwarps. 

paper, was probably local and not prof?tind. The p In- This opinion had b en re.ache~ by the w~t~r IndepeJ?-dcipal orogeny in the Rocky Mountains of Colortd0 ently in an attemp to visualize th.e regiOnal tectomcs. 

probably came after the close of the Cretaceous, a a The Sanpete Va ley structure differs from those ·of 

date not yet established. -southern Utah in eing somewhat more complex, but 

PRE-FLAGSTAFF MOVEMENT 

The disturbance here called the pre-Flagstaff mo 

ment is postulated on the basis of the unconformity e- neath the Flagstaff limestone, whose essential· fe.atu es~ _ and especially those that bear on the questiOn of 

orogeny, are described and discussed in the parts of is 

report devoted to the North Horn and Flagstaff or- mations; As here interpreted, this·movement produ ed 

_a single fold, probably asymme.trical1 steeper on~he 

east and not more than 5 or 6 miles w1de. It was c n- fined to the belt now occupied by Sevier and San ete 

Valleys and parts of the western margin ·of the Was a ch 

-Plateau. The disturbance probably did not affect ihe _ rocks in the Gunnison Plateau, where the North H rn 

and Price River formations are present and confo illable with the Flagstaff. It is possible, as pointed ut 

in the discussion of the Flagstaff limestone, that he 

structure-is, limited to a small area around the Ma ti- Salina district. Although its actual extent is not et 

absolutely demonstrated, this fold is thought to occ py 

at least the southern half of the western border of he 

Wasatch Plateau, and perhaps more. 

The folding took place within the rather 1nar ow 

stratigraphic interval between the uppermost No th 

Horn and the basal Flagstaff. Despite this precise vi- dence of position in ~he local stratigraphic colu n,-

however, the age of the movement is not accura$ly 

know1_1, because of uncertainty as to the age of th.e Fl g-· staff limestone. Available data, -presented elsew ere 

in this report (p. 136), suggest an age near the mid le 

of the Paleocene. If this assignment is correct, there re 

no known episodes of folding in the eastern part of he 

Cordillera with which the centr. al . Utah disturbai ce ~ight be correlated, possibly excepting the movem nt 

that occurred in southwestern Wyoming during the in- terval bet~een Ada ville and Evanston time. 76 If he 

Flagstaff limestone should prove to be of Wasatch 

the folding might be shown to be contemporaneous · th 

that which occurred between Fort Union and Wasa ch 

time in areas farther north; but the evidence now av il- able on the age of the Flagstaff suggests Fort Un on 

rather than Wasatch. A middle Fort Union -movem nt 

would add to the complexity of the Cordilleran oroger ic 

succession, and a simpler interpretation might s em 

certain features of he complexity support the concel?t 

of deep-seated thr sting. The pre-Flagstaff flex~lr~.IS 

superposed on an(~ der fold, the ea;sternmost anticl.Ine 

of the early Larami e orogeny, but Instead of renewing 

movement" on all o the older anticline, as it probably 

would ,have done i caused by general compression in 

the upper layers, i is restricted to t~e eastern 'part of 

the early fold. Thi suggests partly Independent structural control; the ol er anticline may have played a part 

in localizing thela er yield, and its longer gentle flank 

may have served as a strut in which the stress was concentrated but the 1' calization of the pre-Flagstaff flexure on th~ east flan of the early fold indicates concentration of forces di erent from those of the early Lara-;-

mide compression' ; such resolution might well ha':e 

resulted from a thr st rising steeply f~om below. The 

isolation of the p e-Flagstaff fold, hke that Qf the 

southern 'Utah mon clines, argues against pr~ssure pervading the upper l yers and favors deep-seated move- ' 

ment concentrated · n localized thrusts. These features 

of form and interp tation are impressive in suggestion 

of a common type of origin for the Sanpete Valley 

structure and those o the east and south. · 

The regional str tigraphic .r~lations also give. reas~n 

for suspecting ~ c mmon orig.In. Tl_le mon0el~nes m 

southern Utah Inv lve the Kaiparowits formatiOn, of 

late Cretaceous age and are overlain nonconformably 'by strata· assigned to the Wasatch fo,rmatio~. 79 ~he 

Kaiparowits forma ion_ is no ol.der t~an the Pnce Rr~rer 

and may be young r; It contains dinosaurs suggestive 

of Lanc"e age. The strata assigned ~o the vV as~tch fo:-

Ination have yielde very few. fossils and ~hmr age. Is 

uncertain. As is b ought out 1n the foregmng descnption of the Flagst ff limestone, it is entirely possible 

that part of 'the asatch formation as described for 

southern Utah is e uivalent to the Flagstaff of central 

Utah. All of it mi ht just as well be, as far as regional evidenc~ goes. The question probably cannot be .settled 

short of finding dia ostic fossils, becaus~ the outcrops 

of central and sout ern Utah are separated, their nearest approach being about 25 ni.iles. As matters stand, ,· 

76 Veatch, A. C., op. cit. p. 75. 77 Gregory, H. E., and foore, R. C., 'l'he Kaiparowits region: U . . s.· Geol. Survey Prof. Paper 164, pp. 116-124, pl. 17, 1931. Baker, A. A .. op. cit., fig. 2. · 1 

7s Baker, A. A., op. crt.; p. 1501--1502. . 7

9 Gregory, H . E., and oore, R. C., op. c1t., pp. 116, 113. 

\ -

•I 
156 SHORTER · CONTRIBUTIONS T.O GENERAL GEOLOGY, 1943-45 

w~th definite conclusion impossible, the writer is in- . - clined tC? think, on the basis of considerable regional 

observatiOn, that the 'V asatch formation of the south 

is equivalent·to the Flagstaff of central Utah and that 

the monoclines of the Colorado Plateau are contemporaneous with the pre-Flagstaff fold of Sanpete 

Valley. · 

PALEOGEOGRAPHY AND GEOLOGIC HISTORY 

DIAGRAMMATIC RECONSTRUCTIONS 

The facts now a"vailable for central, eastern, and 

n?rtheastern Utah permit interpretation of geologic ~Istory an~ reconstruction of paleogeographic conditions .sufficiently c~mplete to justify representation .. ro this end the wnter has prepared four block dia- grams (fig. 21) which portray the geography of the 

n~r~hern half <?f Utah east of longitude 113° W. at four 

cntlcal stages In .the Upper Cretaceous; they also show 

the development of the geosyncline and the regional 

structure up to the close of the Cretaceous. ·In order 

to show anything at all of the section in eastern Utah 

the vertical scale of the diagrams is exaggerated a httl~ ~ess tha:n four times. The mountain belts are highly g~nerahzed as tC? form and are intended merely to indiCate rug~ed hig~la ds in approximate position. It 

was found Impracticable on the available scale to rep-· resent the precise type of topography that would have 

resulted from early dissection of known folded structures in the eastern Great Basin. As to general trend 

the mountain areas are probably correctly placed~ Latitude in interpretation of some of the data would 

permit alternative locations of some features· for example, in the diagram for the lower Coloradd the site 

of Salt·Lake qity is shown in the piedmont gravel belt, 

whereas ~hat Site may have been occupied by mountains. In the diagram for late Montana time the shore line is 

drawn to emphasize the maximum possible withdrawal 

of the sea, the intention being to bring out the extent 

of the Castlegate sandstone member of the Price River 

formation. The shore may actually have lain farther 

west at the time of maximum withdrawal. 

The four diag~ams nec_e sarily show only generalized 

and representative conditiOns for thejr specific times 

and th~y need to be supplemented by an account of th~ successiOn of events, or perhaps it is more appropriate 

to say that they serve as illustrations for the account 

of g~ologic hi~tory. ~he elements of this account vary 

cons1dera:bly In certain_ty of interpretation, and the attemp~ Is made by s~Itable qualification to indicate 

something of the relative . certainty. It is impossible 

however, to make this differentiation complete and th~ reader may judge for himself, in terms of the facts 

given in foreg?ing parts of the report, the degree of 

cogency attaching to the postulated events. 

UPPER JURASSIC AND LOWER CRETA·CEOUS 

. During the early and !fiiddle parts of Upper Jurassic 

time central Utah was Invaded by the widespread sea 

that covered large parts of the Cordilleran and adj acent regions~80 In its earliest stages this sea spread gray 

mud and silt, l?cally with some limestone, over central Ut~h; but as time we~t on closed basins developed· in 

whiCh con~entrated bnnes gave rise to beds of gypsum, 

locally. thiCk _and pure, but generally irregular, thin, 

and mixed with mud. · Later, great quantities of red 

mud were deposited, and closed basins again developed, 

this time to form deposits of rock salt from the brines 

that were concentrated in them. Salt-forn1ing conditions may have existed also in the early stages of the 

marine invasion. _ This succession of events, covering 

the deposition of the Twelvemile Canyon member of the 

Arapien shale, holds for the part of central Utah now 

occupied by the northern part of Sevier Valley, but reconnaissance observation suggests that, in other areas 

nearby, conditions were somewhat different. The zones 

so far recognized in the Arapien shale have not been 

well enough correlated across cent1·al Utah to make sure 

of the relative successions of events at different places; 

it is possible, for example, that the times of thick salt 

deposition in Sevier Valley correspond to times of thick 

gypsum deposition farther north and west, and it is 

known that to the north the early stages of the invasion 

were marked by lime-forming conditions. ' 

At all places seen by the writer the salt occurs witl;-

out gypsum, and the gypsum without salt. In the district near Salina the two occur in different zones of the 

Arapien ~hale, as indicated . in the order of deposition 

given above, but the relation of these deposits to other 

occurrences of salt and gypsum in nearby districts 81 is 

not known. The app,arent localization of the thick deposits of gypsum, and to some extent the salt also, suggests deposition in restricted basins of small area. 

The geiie~ al problem of explaining such pure-and mutually exclusive deposits as precipitate from sea water, 

though widely studied . by geologists and chemists, lias 

not been completely solved, and accurate reconstruction 

of conditions ·in central Utah during the' Upper Jurassic is yet impossible; the geologic relations of the Utah 

deposits are not known in sufficient detail to afford a 

contribution to the problem. The features of distribution mentioned above, however, leave open the possibility that some such condition as that proposed by 

Branson 82 may have existed; that is, many local basins 

separated by barriers high enough to prevent circulation of the deeper layers of water but low enough to 

allow free passage of partially saturated brines, with 

gypsum precipitating out in the basins nearest the open 

sea, and sa-lt in the more remote basins to which only· brine free of calcium sulfate had access. In fact, if it 

is ever possible to correlate the zones of the Arapieii 

shale across the area, their occurrence may afford an 

interesting test of Branson!s hypothesis; thick, pure 

salt beds occur in the northern part of Sevier Valley, 

and thick, pure gypsum near Nephi and Levan. However, even if the type of situation pictured by Branson 

does appear favorable, it must be .remembered tha£ 

nearly perfect balance is required to produce mutually 

exclusive and nearly pure deposits of salt and gypsum. 

After the epoch of salt and gypsum deposition open . sea again prevailed, and alternating layers of red and 

greenish-gray silt and mud were deposited, the red 

predominating, and occasional inroads of sand occurred. 

This condition lasted long enough for the deposition of 

3,000 feet or more of sediment, the Twist Gulch member 

of the Arapien shale, and by the time the uppermost of 

these beds was laid down the geosyncline had been. f:LCcentuated by the addition . of 10,000 feet, more or less, 

of Jurassic sediments. The general similarity of these 

sediments to those of the same age in eastern Utah and 

80 Crickmay, C. H., Jurassic· history of North America-its bearing on the development of continental structure: Am. Philos. Soc. Proc., 

vol. 70, pp. 87- 89 (maps 8, 9, 10), 1931. . 81 Eard~ey, A. J., S~ratigr3;phy of the southern Wasatch Mountains, 

Utah : M1ch. Acad. SeL Papers, vol. 18, pp. 332- 334, 1933. , 82 Brans?n, E . B., 'l'he origin of thick gypsum and salt deposits: Geol. 

Soc.Amenca Bul_I., vol. 26, pp. 231-242, 1915. 
/ 

LATE MESOZOIC AND--EARLY CENOZOIC HISTORY 157 

A. Early Color a do time 

/ 

D. t ime (North Horn) 

FIGURE 21.-Block diagrams showing Utah north of latitude 39°30' at late Cretaceous time. 
/ 

'' 

I. 

158 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1943-45 

the great difference in thickness ( 10,000 :feet vs. 2,500) 

testify to the · pronounced but slow differential subsidence of the geosynclinal belt. 

In the latest Jurassic time flood-p~ain sediments· of 

the Morrison formation were deposited widely over the 

region to the east, but, as already discussed in this report (p. 126), it is not known whether they spread as far - west as central Utah. For the closing stages of the 

Jurassic, then, the account of geologic history must yet 

be vague. Regardless of whether Morrison sediments 

were deposited in central Utah, the area began in late · Jurassic time to undergo that remarkable period of 

stagnation which' lasted through the Lower Cretaceous 

and produced the phenomenon, universal in the Colorado Plateaus, of basal Upper Cretaceous (Dakota~ 

or lower Mancos) overlying undisturbed Morrison beds 

with no sign of angular discordance. During Lower 

Cretaceous time the area was almost certainly positive, 

and erosion was either phenomenally uniform or very 

sluggish, almost inactive. The writer prefers the second 

interpretation, although critical facts :for basis of decision seem to be lacking; it is not inconceivable that Lowe~ Cretaeeous sediments were deposited and removed in a cycle of erosion incited by eustatic change 

of sea level an:l carried to complete peneplanation with 

a base level near the top of the horizontal Morrison 

strata. Uplift uniform enough to allow erosion of the 

existing buried plain on the top of the Morrison formation is almost inconceivable/ In any case, regional 

distribution of Lower Cretaceous sediments in· North 

America does not favor the concept; the known basins 

of deposition do not suggest extension into the Colorado Plateaus. It is most likely that Lower Cretaceous 

time was geologically neutral in Utah. 

EARLY UPPER CRETACEOUS (COLORADO) 

Not long after the beginning of the Upper Creta- -ceous, an orogenic pulse penetrated the region, :folding 

the rocks in a belt trending about N. 15° E., which lay 

not far west of the present southern Wasatch Mountains. The highlands thrown up in this folding were 

rapidly eroded, and the debris resulting from this active 

destruction was swept eastward, boulders and coarse 

gravel accumulating to great thickness in the piedmont 

belt and finer sediments traveling farther out across 

the lowland area bordering the sea. In early Colorado . time the lowlands east ~f the foothills were occupied in 

close order by flood plains and a coastal sand belt, the 

average total width of which· from the margins of the 

gr-avel fans to the muddy bottom of the sea was less 

than 20 miles. At times there appeared locally on the 

flood plain small lakes in which limestone was deposited. These lakes were possibly caused by drainage obstruction incident to the rapid accumulation of coarse 

sediments, and those near the mountains may well have 

been impounded by coales~ing gravel fans, after the 

fashion postulated by Eardley 83 for similar lime-depositing lakes of later age_. The lakes were surrounded by 

accumulations of highly varied sediments, in which 

brightly colored muds and sands abounded as well as 

gravel of many kinds~ In parts of northern Utah, at 

approximately the same time, coal-forming swamps 

flourished on the coastal plain, not far from the sandy 

beach of the lower Mancos sea. 

Through early Colorado time the distribution of environments above described was :fairly uniform, but in 

late Benton (Carlile) time an arm of the sea invaded 

, ' 

the belt east of the piedmont, cut off :from the open sea 

to the east by a sandy peninsula that was repeatedly 

covered. by coal-forming swamps. In Niobrara time the 

sea overswept this peninsula, :for a while invading the 

piedmont gravel belt and skirting the :foothills of the 

mountains. Toward the close of Niobrara time, perhaps in early Montana, a fresh volume of coarse gra~el 

was spread eastward, probably due to renewal of uphft 

in the mountain belt and perhaps a genuine orogenic 

movement. 

THE GEOSYNCLINE 

By late Colorado time the accumulation of sediment 

in the piedmont belt had reached notable proportions, 

and a profound geosyncline occupied the site of the 

Wasatch Mountains; the Paleozoic and Mesozoic rocks 

totaled over 40,000 feet.in thickness, most of which was 

in the huge masses of Pennsylvanian, Jurassic, and 

Cretaceous strata. This prodigious accumulation marks 

an extension of the regional trend in tectonic history, 

already noted for the Paleozoic,84 of pronounced eastward shift in the site of heavy sedimentation. · From 

t;he Cambrian geosyncline of western Utah and eastern 

Nevada through the Carboniferous trough of the 

Oquirrh-southern Wasatch region to the eastern marginal depression of Jurassic and Cretaceous times th 

succession is mo~t impressive, and although not in perfect scheme, yet is well enough developed to suggest a 

certain regularity in tectonic process. Several features 

of this regional developm nt are worthy of notice, and, 

to serve as basis for brief discussion, the releva_nt events 

and conditions for the territory between western and 

central Utah are summarized in the following table. 

Generalized r ecord of sedimentation, Cambrian to Eocene, 

between western and central Utah 

Approximateage 

(millions· of years), 

as generally 

accepted 

550-450 

30Q-200 

l50± 

100± 

70± 

55± 

Divisions 

Cambrian . . __ ________ ------ ___ _ 

Ordovician thx:ough Devonian __ Carboniferous. _______ ----------

Triassic, · Lower and Middle 

Jurassic. Upper Jurassic __ ______________ _ 

Lower Cretaceous __ ___________ _ 

Colorado._ ---------------------

Early Montana _______________ _ Late middle Montana __ , ______ _ Late Montana __ ______________ _ 

Lance and early Fort Union __ _ 

Fort Union and Wasatch ______ _ 

Conditions and events 

Profound subsidence in western belt; limestone deposition. · Relatively positive conditions. 

Profound subsidence in central-eastern 

belt; sandstone and limestone deposi- . tion . Relatively positive conditions. 

Profound subsidence in eastern belt; 

shale deposition, local limestone, salt, gypsum. Region totally positive. , Orogeny in central belt. 

Profound subsidence in eastern belt; coarse clastic deposition. Relatively positive conditions. 

Early Laramide orogeny, eastern belt. 

Profound subsidence in eas~rn belt; coarse clastic deposition. Relatively positive conditions. · Pre-Flagstaff folding. Minor geosyncline in western Uinta 

Basin; lacustrine sedimentation. 

It is evident that there were :four epochs of major 

subsidence followed by two lesser ones, all separated by 

longer periods of relatively positive condition. These 

sa Eardley, .A. J., .A limestone chiefly of algal origin in .the Wasatch · conglomerate, southern Wasatch Mountains, Utah: Mich . .Acad. Sci. 

Papers, vol. 16, pp. 405-406, 1932. It should be noted that the specific theory here referred to does not hold for the limestone described by · Eardley, which, as suggested by him in alternative hypothesis, is. part of 

the extensive Flagstaff limestone. 84 Gilluly, James, Geology and ore deposits of the Stockton and Fairfield quadrangles, Utah: U. S. Geol. Survey Prof. Paper 173, p. 39, 1932. 
i 

LATE MESOZOIC AND EARLY CENOZOIC HISTORY UTAH 159 

time intervals, especially the longer positive periods, 

are progessively shorter in ascending order; each interim between epochs of strong and localized subsidence 

is roughly half as long as its predecessor. ·The epochs 

of geo~ynclinal acc~ntuation se~ni to follow the same 

sort of rule as that brought out by Stille 85 for orogenic 

pulses, in that compared to the intervals separating 

them they are episodic in nature, although .· doubtless 

more broadly so than the orogenies. Further,, they recurred, shifting eastward·, at regularly increasing pace. 

Whether this quickening of pulse is accidental cannot 

be said, but it does harmonize with, the broad trend of 

the earth's tectonic history, in which the crowding· of 

orogenic episodes toward the present is plainly evident,86 and it is thus another suggestion of crude regularity in crustal m'ovement. -

Anot.her point worth noting is that the type· of sedimentatiOn changed progressively eastward, from dominantly lime-forming conditions in the older Paleozoie 

to coarse clastic deposition in the late Mesozoic. The 

coarse materials of the early upper Cretaceous geosyncline accumulated in a sort of foredeep fronting the 

newly folded belt, as did those also of late Montana 

time, and these phases of the geosynclinal development 

seem to be related somehbw to the orogenic performance. 

The older geosynclinal phases probably were not associated with orogeny; sections known in the eastern Great 

Basin give no evidence of Paleozoic folding, but the 

territory has only been sampled geologically, and local.: 

ized folding might remain to be-discovered. Further, 

the record· of ~riassic and. Jurassic times in western 

Utah is notably incomplete. 

Not only did the successive downwarps come closer to 

one another in time, but they crowded together in space 

as welL The areas of thick Pennsylvania and Jurassic 

o':'erlap, anq the thick Jurassic is practically coincident 

with tl).e thiCk Cretaceous, whereas the areas of thick 

Cambrian are more th'an 150 miles west of the thick 

Pennsylvanian. 

Another point of interest that might be noted in con- . nection with ·the sediments of the geosyncline is the 

resemblance of the Indianola group and the Price River 

and North Horn succession to the Alpine Flysch and M~lasse .. Especially close is the similarity between the 

Pnce River and North Horn formations and the 

Molasse as described by Heim 87 ; even down to details 

of lithologic character and distribution of 'sediments 

the two agree remarkably. The writer has never seen 

the Molass and is aware of the danger in making close 

comparisons from written descriptions alone but' 

Heim's account is so clear that little doubt is po~sible. The only important difference is that the Price River ~nd North Horn; although locally folded and thrust 

In the western part of the Wasatch Plateau and adjacent country on the west, are neither so extensively nor 

so profoundly deformed as the Molasse of Switzerland. 

EARLY TO MIDDLE MONTANA 

In early Montana time the sea, which had reached its 

greatest local extent in Niobrara time, began slowly to 

retreat, oscillating or pausing in its eastward movement 

so that the littoral and bordering continental sediments · intertongue with the offshore marine beds. In the 

geosyn~li~e sedimentation diminished in volume, the 

floor sinking more slowly, and finer sediments were 

deposited; the highlands. to the west had been worn 

down to a stage at ~ich the streams were near grade. 

..In the folded belt ositive 'evidence of this condition 

is lacking, but it is inferred from the Montana sediments not far east f the marginal fold. In middle 

Montana (Blackha . k) time coal-forming swamps 

overspread the regi n more widely than ever, and the 

thick coal beds of , 1e present Wasatch Plateau were 

laid down. Follow· g the eastward migration of the 

sea, the belt of ex ensive coal ~wamps, always near 

shore, moved eastw rd into the region of the Bbok Cliffs, and in centr l Utah the latter par.t of middle 

Montana time broug t extensive inland fleod plains on 

which fine sands an muds were spread but which supported few ·coal sw ps. By the time the uppermost 

strata of the Blackh wk formation were depositBd the 

shore had 'retreated far to the east, to the region east 

of the present locati n of Green River. · 

NTANA AND LAN·CE 

Following the dep sition of the Blac~hawk sediments 

came a sharp oroge ic paroxysm, the early Laramide, 

in which the sedime ts of the geosyncline were folded 

and thrust eastward the rising mass ·being rapidly cut 

by erosion into rugg d mountains. The r,esulting rock 

debris was vigorous y swept eastward, spreading into 

the marine basin to form the gigantic tongue of the 

Castlegate sandstone member of the Price River formation. In the newly f rmed piedmont district pediments 

developed much like hose of the present-day, which are 

widespread in the C rdilleran region, and these pediments wer~ deeply b ried under coarse rubble. At least 

in the ,vicinity of th 4Gth Parallel the mountain front 

was steep and seve l thousand feet high; Eardley88 

·estimates 6ver 10,000 feet, and it may have approached 

that figure, but the t~mate take§ no account of movements since the dep sition of the conglomerate and is · based on uncertain a sumptions respecting the amount 

of post-orogenic eros on; it n1ay be too high. The preFlagstaff and later ovements, which were strong east 

of the southern Was tch Mountains, doubtfess altered 

the original relatio s between the conglomerate and 

the -parent. mass an may have, raised the mountain 

bl9ck. At all events the mountains were high, and' it 

is interesting to obs rve that in general contour they 

were much like the southern Wasatch of . today; the 

line of their east fro t -virtually coincides with that of 

the east front of the vV asatch rai1ge south of Spanish 

Fork, and they end d in a southern pro.montory, the 

forerunner of Moun N ebo. The site of the Gunnison 'Plateau was overswe t by Price River sediments, which 

now overlie the Indi nola strata in mildly angular un- . conformity, near the axis of a broad syncline that separates the southern ontinuation of the Mount Nebo 

anticline f_rom the asternmost fold in the Sanpete 

Valley district. In t e central belt of this syncline the 

Indianola· strata wer only slightly eroded before the 

Price River gravels overspread the region. The an- · ticline to the east;.h wever, was completely truncated, · as seen in' the wid~s read surface beveling the Indianoia deposits, on w ich the basal conglomerate of the 

Price River formati n was deposited in the western 

Wasatch Plateau an the eastern Gunnison Plateau. 

The mountai1_1 front pro?a9ly veered southwestward 

85 Stille, Hans, Grundfrag n der vergleichenden Tektonik, p. 44, 1924. ss Stille, Hans, The prese t tectonic state of the earth: Am. Assoc. 

Petroleum Geologists Bull., ol. 20, p. 852; 1936. 87 Heim, Albert, Geologie er Schweiz, vol. 1, pp. 39-95, Leipzig, 1919. ss Eardley, A. J., Structure and physiography of the southern Wasatch 

Mountains, Utah : Mich. Acad. Sci. Paperst vol. 19, pp. 391-392, 1934. 

. . ' 
160 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1 9 4 3-4 5 

fron1 the site of Mount N ebo, lying west of the present 

Gunnison Plateau; the overturned fold of Mount N ebo 

swings sharply westward in strike at the southern end . of the Wasatch Mountains. · (See fig. 21.) 

As the early Laramide mountains were worn down, · successive profiles of depositional equilibrium were attained in the aggradational belts to . the east, and the 

flood-plain areas shifted westward ; the finer sediments 

now constituting the North Horn formation were de-. posited closer and closer to the mountains until they 

overlapped the remains of the steep front and· partly 

buried it in the latitude of Thistle. Gravel fans continued to exist, however, as the dominant sedimentin the 

narrow piedmont belt. The flood plains were occupied 

by shifting lakes in which the limestone and evenly 

bedded silts of the North Horn formation accumulated. 

This type of sedimentation went on through the close of 

the Cretaceous and continued without interruption into 

Paleocene time. 

PALEOCENE (FORT UNION) 

Not lop.g after the beginning of Tertiary time, as 

judged by the thickness of sediment deposited, the belt 

now occupied by Sanpete and Sevier Valleys was dis- . turbed by the movement described in this report as the 

pre-Flagstaff movement. This disturbance produced a 

single anticline in the eastern part of the valley belt and 

the foothills of the Wasatch Plateau, to both east and 

west of which sedimentation apparently went on without interruption, the flood plains receiving fine sands 

and muds exactly as before the disturbance. The anticline was planed off by erosion, and after the development of a nearly level erosion surface on the folded 

Cretaceous and Jurassic rocks the entire region from 

central Utah eastward as far as the western Book Cliffs 

was.. overswept by a shallow lake in which the dominantly calcareous sediments of the Flagstaff limestone 

were deposited. This lake may have resulted from 

obstruction of drainage produced by the pre-Flagstaff 

deformation; reasons have been given for suspecting 

that this movement was widespread in central, eastern, 

and southern Utah. 1t may, on the other hand, have 

resulted from geosynclinal down warping. As time went 

on the lake slowly chan~ed in outline and in configuration of bottom, spreading different kinds of sediment 

in complicated intertonguing layers and lenses; deltas 

encroached on it, the marginal flood plain following, and 

for a time in the central part of the Wasatch Plateau 

an enclosed basin contained saline waters from which 

gypsum was deposited. In the-main, however, the early 

stages of the Flagstaff lake were a time of widespread 

clear water, in which limestone was deposited, covering 

all of central Utah and probably much territory beyond. 

At this time began the long series of volcanic outbursts 

that were to dominate, the scene in later Tertiary timelocally the Flagstaff limestone contains interbedded 

fine white ash, probably rhyolitic in composition. 

EOCENE (WASATCH AND GREEN RIVER) 

At this stage the dating of events becomes less precise, 

and it is impossible for lack of diagnostic fossils to interpret the beds above the Flagstaff in ,terms of the 

standard Eocene time scale. Approximately in Wasatch 

time, however, flood-plain sediments swept into the region from the east, blotting out ·much of the Flagstaff 

lake and spreading over most of central Utah. At the 

maximum extent of the flood plain the lake shore extended from the country west of Soldier Sum_mit southwestward, curving back and forth across the territory 

now occupied by Sanpete and northern Sevier Valleys. 

Later the lake again expanded eastward, the shore line 

oscillating and producing intricately interfingered 

bodies of sediment, until it attained maximum extent 

atthe time the major body of the Gre~n River formation was deposited: The paleogeography of this remarkable lacustrine development has been well worked 

out by Bradley.89 In the western~ districts the lake 

persisted through the time of deposition of the Wasatch 

sediments farther east, but the type of sediment changed 

from dominantly limestone to dominantly mud, some of 

it sapropelic and destined to become oil shale. In the 

Uinta Basin the remainder of Eocene time is fully recorded in the Bridger and Uinta formations, but ·in 

central Utah the Green River strata are the yom:~gest 

that are even approximately placed in the time scale. 

89 Bradley, W. 1!., The varves and climate of the Green River epoch: 

U. S. Geol. Survey Prof. Paper 1.58, pp. 87-110, 1930. 

/ 
INDEX 

Page 

Abstract------------------------ 117-118 

Acknowledgments ----------------- 118 

Allen Valley shale, description oL 127-128, 

133 

Arapien shale, age and correlation oL 125 

definition oL----------------- 123 distribution oL __________ __ _ 123-124 

fossils in------------- --- ---~- 125 lithologic character oL _____ 124, pl. 18 

stratigraphic relations oL ____ 123, 141 

thickness of__________________ 125 

Twist Gulch member oL ______ 124, 125 

Bennion Creek, section of Price River 

formation on_________ 132 

Blackhawk formation, character oL__ 120 · stratigraphic position oL______ 141 

Castlegate sandstone member of Price 

River formation ___ __ 130- 132, 

141, pl. 20 

Colorado age, rocks oL ___________ 126-127 

Colorado time, conditions during __ 157, 158 

Colton formation, age and correlation of ________________ __ 139,141 

character and distribution oL___ 139, . pl. 23, A Cretaceous period, condition during__ 157, 

158-160 

Cretaceous systems, formations oL 126-135 

Cretacious-Tertiary boundary problem---------------- 142-149 

Eocene epoch, conditions during_____ 160 

Epeirogenic movement, significance Of------------~---- 145-146 

Flagstaff limestone, age and correlalation Qf_________ __ __ 136 

description of- ______________ 135-136 

extent and regional relations oL 135-

136, pi, 22 

unconformity beneath__________ 136- . 13~ 155- 156, pl. 25 

Fort Union time, conditions during___ 160 

Fossils, valu~ oft as. markers of geo- logic time __________ 146-149 

Funk Valley ·formation, descrip- tion oL ____ 128, 133, pl. 19, B 

Geologic history of the area------ 156-160 

Geologic time, basis for subdivision 

of------------------- 143 Geosyncline in the area ___________ 158- 159 

Gilmore, C. W., fossils identified by__ 134 

Green River Canyon, geology oL____ 140, . 142, pl. 23, A Green River formation, character oL 120, 

pl. 23, B stratigraphic position oL_______ 141 use of term___________________ 140 

Green River time, conditions during__ 160 

Gunnison Plateau, section at base oL 129 

Hjork Creek, section north oL ____ 129- 130 

Indianola group, definition oL ____ 126-127 

members oL ___ 127-130, pls. 19, 21, B 

stratigraphic position oL_ 141, pl. 25, B undifferentiated _____ 128-130, pl. 21, B 

Jurassic period, conditions during __ 156, 158 

Jurassic system, formations of_ ___ 123-126 

Lance time, conditions during_ 157, 159- 160 

Laramide orogeny _______ 144, 149, 152- 155 

Laramie problem---------------- 142-145 

Mancos shale, stratigraphic position 

of------------------- 141 

Page 

Montana age, rocks of______________ 130 

Montana time, conditions during __ 159-160 

Morrison ( ?) formation, description of_________________ 125-126 

North Horn formation, age and cor- relation oL _________ 134-135 

definition of-_______ 132-133, pl. 23, A 

fossils in--------------------- 134 

regional characteristics oL----- 133 

relation Qf, to adjacent formations _______ 133-134, 141, pls. 

22, B, 23, A, 24, A, 25, A sections oL _____________ 133, pl. 22, B 

Orogenic movements, nature and ex- tent of_ ____________ 149-156 

significance of- ______________ 143-145 

Orogeny, early Laramide __ 144, 149, 152-155 

mid-Cretaceous __________ 149, 150-152 

pre-Flagstaff ____________ 149, 155-156 

Paleocene, use of term_____________ 135 

Paleocene epoch, conditions during___ 160 

Paleogeography of the area-------- 156-160 

Paleontologic record, significance of __________________ 146-149 

Post-Castlegate rocks, section of_____ 140 

Pre-Flagstaff movement, interpreta- tion of_ ____________ 155-156 

Price CanY'>n, section in_ ___________ 120 

Price River formation, ·age oL------ 131 

Castlegate sandstoHe member 

of- ______ 130-132, 141, pl. 20 

definition oL----------------- 130 distribution oL_______________ 130 

fossils in_____________________ 132 

lithologic character oL_ 130, pis. 20, 21 

regional relations of_ _________ 131-132 

sections oL----------------- 120, 132 

Sego sandstone member oL_____ 142 

stratigraphic relations oL______ 122, 

130- 131, 141, pl. 24, B 

Reeside, J . B., Jr., fossils identified biy 125, 32, 134 

Sanpete formation, description of____ 127 

Sedimentation, between western and· central Utah, record oL 158 

Sego sandstone member of Price River formation_____________ 142 

Sixmile Canyon formation, descripQf -----'-------------- 128 

Star Point sandstone, stratigraphic position of___________ 141 

Structure in the area-------------- 122, 129, 133, 141, 157, pls. 24, 25' 

Tertiary system, formations oL ___ 135-140 1 

Tuscher formation, stratigraphic posi- " tion oL 140, 141, 142, pl. 23, A 

Twelvemile Canyon member of Arapien shale, character of-__________ 124-125, pl. 18 

Twist Gulch member of Arapien shale, character QL _________ 124, 125 

Wasatch formation, correlation oL 120-122 / use of name ______ :._ __________ 137, 139 

Wasatch time, conditions during_____ 160 

Wasatch Plateau, description Qf ___ 118-119 

reconnaissance east oL-140-142, pl. 23 

stratigraphic units in_ 120-123, 129, 141 

West Tavaputs Plateau, geology of__ 140, · 141, pl. 23, B 

161