CLASTIC LARAMIDE SEDIMENTS OF THE WASATCH

HINTERLAND, NORTHEASTERN UTAH

by

Daven Craig Mann

A thesis submitted to the faculty of the University of Utah in partial fulfillment of the requirement for the degree of

o • •

Master of Science

in

Geology

Department of Geology and Geophysics

University of Utah

Summer 1974 UNIVERSITY OF UTAH GRADUATE SCHOOL

SUPERVISORY COMMITTEE APPROVAL

of a thesis submitted by

Daven Craig Mann

I have read this thesis and have found it to be of satisfactory quality for a master's

degree. * /• %

Li, /Eugene Call4.ghan [ChairmartySupervisory Committee

T have read this thesis and have found it to be of satisfactory quality for a master's j degree.

Date rancis W. Christiansen Member, Svipervisory Committee

T have read this thesis and have found it to be of satisfactory quality for a master's decree.

Jonathan H. Goodwin [ember, Supervisory Committee

UNIVERSITY OF UTAH LIBRARIES UNIVERSITY OF UTAH GRADUATE SCHOOL.

FINAL READING APPROVAL

To the Graduate Council of the University of Utah:

I have read the thesis of Daven Craig Mann in its final form and have found that (1) its format, citations, and bibliographic style are consistent and acceptable; (2) its illustrative materials including figures, tables, and charts are in place; and (3) the final manuscript is satisfactory to the Supervisory Committee and is ready - for submission to the Graduate School.

Approved for the Major Department

Chairman/Dean

Approved for the Graduate Counci

Sterling M. McMurrin Dean of the Graduate School ACKNOWLEDGMENT

Acknowledgment is made to the Utah Geological and Mineral

Survey which financially aided the author while doing the field work. The survey staff contributed many hours in discussing, proof­

reading and typing the manuscript. Amoco Production Company graceously undertook to secure the three K/Ar radiometric dates which were essential to the study.

Numerous people aided and encouraged the field work and

preparation of the manuscript. Dr- Eugene Callaghan spent untold

hours both in the field and in reviewing the paper, his eye for

geology is responsible for much of the stratigraphy contained here.

The other members of the graduate committee Dr- Jonathan H.

Goodwin and Dr. Francis W. Christiansen gave very helpful

instructions regarding the manuscript. Gratitude is also extended

to the following people who helped in many ways: Howard R. Ritzma,

Dr. William L. Stokes, Dr. William P. Hewitt, Sylvia N. Goeltz,

M. D. Crittenden Jr. , Clara Warr and the many authors who

treated the subject before me. My wife, Kathryn, also deserves

credit for her support and encouragment while taking upon herself

extra burdens in order to allow me more time for this project. TABLE OF CONTENTS

ABSTRACT . • • ix

INTRODUCTION . 1

PREVIOUS INVESTIGATIONS 4

STRATIGRAPHY AND LITHOLOGY 9 Echo Canyon Conglomerate • • 12 History and Age . 12 Lithology 12 Location and Stratigraphy • • • 13 Evanston Formation 15 History and Age • . . 15 Lithology 15 Location and Stratigraphy 19 City Creek Canyon Volcanics . 22 History and Age • • 22 Lithology 23 Location and Stratigraphy . • 25 Wasatch Formation 27 History and Age » • • 27 Lithology . . * 29 Western Conglomerate Facies 29 Eastern Sandstone-Mudstone Facies . 42 Fowkes Formation 47 Norwood Tuff 49 Perrys Hollow Fanglomerate 52

CORRELATION 56 Echo Canyon Conglomerate - Price River and Bennion Creek Formations .56 Currant Creek Formation and North Horn Formations - Evanston Formation . . . . » • • 59 Colton Formation - Wasatch Formation • • 60

PALEOCURRENT STUDY 62 General Statement • 62 Procedure 63 Results • 64 Echo Canyon Conglomerate 64 TABLE OF CONTENTS CONTINUED

Evanston Formation 66 Wasatch Formation 68

PEBBLE COUNT 73

STRUCTURAL HISTORY 77 General Statement 77 Phases of the Laramide Orogeny ...... 81 Early Laramide Orogeny - Late Cretaceous. . 81 Late Phase of the Early Laramide Orogeny- Late Cretaceous • 83 Mid Laramide Orogeny - Late Paleocene to Early Eocene 85 Late Laramide Orogeny - Late Eocene to Early Oligocene 86

ECONOMIC AND ENGINEERING GEOLOGY 90

Landsliding 91

CONCLUSIONS . 93

BIBLIOGRAPHY 96

APPENDIX 102 Measured Section 103 VITA 113 ILLUSTRATIONS

FIGURE PAGE

1. History of the stratigraphic nomenclature ... 5 2. Estimated basins of deposition in the Wasatch Hinterland 10 3. Idealized cross-section of the Wasatch Hinterland 11 4. Iron nodule from the Evanston Formation ... 17 5. Unconformity between the Wasatch and Evanston Formations 21 6« City Creek Canyon volcanics 24 7. Columnar section of the western conglomer­ ate facies of the Wasatch Formation 31 8. Large boulder in the Wasatch Formation . . 32 9» Framework type conglomerate from the Wasatch Formation 34 10. Photomicrograph of the Wasatch Formation . 3 5 11. Siltstone and sandstone beds within the western conglomerate facies 36 12. Festoon cross-stratification in the Wasatch Formation 37 13. Large oncolites in limestone from the western conglomerate facies 39 14. Concentric banding in an oncolite 40 15. Photomicrograph of a probable shell frag­ ment forming the nucleus of an oncolite .... 41 16. Photomicrograph of a gastropod forming nucleus of an oncolite 42 17. Possible root fragments from the Wasatch Formation 43 18. Photomicrograph of possible Goniobasis (? ) from the western conglomerate facies .... 43 19« Fossiliferous limestone cobble of the Park City Formation 44 20. Inner cast of a turtle shell 46 21. Tertiary volcanics of the Wasatch Hinter­ land 48 22. Outcrop of the Norwood Tuff near East Canyon Reservoir 51 23. Preliminary map of the Perrys Hollow fanglomerate 53 24. Perrys Hollow fanglomerate at the mouth of Perrys Hollow • • • 54 ILLUSTRATIONS — CONTINUED

FIGURE PAGE

25. Photomicrograph of the Perrys Hollow fanglomerate 54 26A. Correlation chart for the Wasatch Hinterland and western Uinta Basin 57 26B. Correlation chart for the Wasatch Hinterland and western Uinta Basin 58 27. Compass diagram for the Echo Canyon Conglomerate 65 28. Compass diagram for the Evanston Formation 67 29* Compass diagram for the Wasatch Formation 70 30. Paleocurrent vector map of the Wasatch Formation 71 31. Compass diagram for the Wasatch Formation on the Salt Lake City Salient . . 72 32. Orogenic belts in Utah and Nevada 78 33. Unconformity between the underlying Echo Canyon Conglomerate and the Evanston Formation in lower Echo Canyon • 84 34. Unconformity between the Wanship Form­ ation and the Wasatch Formation 87 35. Unconformity between the folded Paleozoic beds and the Wasatch Formation 87 36. Unconformity between the Evanston Form­ ation and the Wasatch Formation 88 37. Landslide in the elastics in Echo Canyon . . 92

TABLE

1. Pebble count in the conglomerates of the Wasatch Hinterland 7 5 2. Orogenic phases and results in the Wasatch Hinterland 80 3. Radiometric dates for the Late Laramide igneous deposits in the Wasatch Hinterland and adjoining areas 82

PLATE

1. Generalized geologic map of the Laramide Orogenic sediments of the Wasatch Hinterland in pocket ABSTRACT

Four phases of the Laramide Orogeny are mirrored in the molasse-type sediments of the Wasatch Hinterland (Eardley, 1952, p. 52). The present nomenclature for these sediments is, from oldest to youngest: the Echo Canyon Conglomerate, Evanston Form­ ation, and Wasatch Formation. Several tools useful in separating these formations are: (1) lithologic characteristics, (2) pebble

counts, (3) paleocurrent studies, (4) radiometric dating of volcanic

rocks, (5) facies relationships, (6) sedimentary expressions of

Laramide tectonic phases, (7) subsidence basins, and (8) correla­

tion of the sediments with similar units outside the Wasatch Hinter­

land.

The Echo Canyon Conglomerate was deposited from west to

east in the center of the Hinterland. The Evanston Formation con­

sists of a lower conglomerate and an upper sandstone-siltstone

unit. In the Salt Lake City Salient, the City Creek Canyon volcan­

ics (tentative name) which overlie the Evanston Formation were

found to be early Eocene (50 and 55 m. y. ) by radiometric dating.

This date gives a maximum age for the portion of the Wasatch

Formation represented in the Salient where it unconformably overlie

the volcanics. The early Eocene Wasatch Formation was deposi- ted from west to east during a later phase of the Laramide Oroge but because of its large lateral extent it is divided into two facies a western conglomerate facies and an eastern sandstone-mudston facies.

x INTRODUCTION

A broad belt of coarse, clastic sediments occurs along the border between the Great Basin, the Rocky Mountains and the

Colorado Plateaus. The sediments are similar in many respects

to classic molasse deposits of the forelands of the European Alps.

These molasse-type sediments form a long, narrow band of

outcrops that extend almost the entire length of Utah and well into

Idaho. A review by Rutten ( 1962, p. 602-603) explained that the

classical molasse sediments were deposited in subsiding basins

adjacent to abruptly uplifted mountain fronts. As early as 1928,

Cadisch recorded orogenic phases and variations of the rising

Alps by the study of the molasse and flysch sediments in the fore­

lands.

During the Late Cretaceous and Early Tertiary, erosion of

areas uplifted as a consequence of the Laramide Orogeny in the

western United States blanketed the Wasatch Hinterland with thick

sequences of molasse-type conglomerates. Hintze (1973, p. 76)

commented that:

One of the greatest difficulties in all of this work is in identifying the ages of various conglomerates. . . develop­ ment of some uncontestable means of showing the true ages of the conglomerates might modify our understanding (of local geologic history)* 2

Dating of the sediments is indeed a very difficult problem, but the recognition of the different formations, establishing their proper stratigraphic relationships and the tectonic disturbances they mirror can be equally as challenging. For the purposes of dating and distinguishing the molasse deposits in the Wasatch Hinterland, the following tools were found useful: (1) lithologic characteristics,

(2) pebble counts, (3) paleocurrent studies, (4) radiometric dating of volcanic rocks, (5) facies relationships, (6) relationship of the

rocks to Laramide tectonic phases, (7) relationships among different depositional basins, and (8) correlation of the sediments with simi­ lar units outside the Wasatch Hinterland.

This report restricts itself to the Laramide clastic sedi­

ments (i. e. the Echo Canyon Conglomerate, Evanston and Wasatch

Formations) of the Wasatch Hinterland and adjacent areas. The

Hinterland is the region of northeastern Utah, north of the Uinta

Mountains, and east of the Wasatch Mountains. It contains those

portions of Morgan, Summit, Weber, Davis, Salt Lake, Rich and

Cache Counties cut by the drainage systems of the Provo, Weber

and Ogden Rivers. Generally, the Hinterland is an 8000-9000 foot

plateau covered with a veneer of soil and vegetation, except where

canyons cut by stream erosion expose outcrops. The molasse depo­

sits are well exposed in the Hinterland as well as the volcanics,

which provide a limited means for dating the coarser elastics. The

Wasatch Hinterland is of value in studying the Laramide Orogeny because it affords access to sediments of Laramide age without

confusion with the similar Sevier orogenic sediments.

This report develops distinguishing characteristics for the

Echo Canyon Conglomerate, Evanston Formation, Wasatch Form­

ation and relates them stratigraphically to the volcanic Fowkes

Formation, Norwood Tuff and City Creek Canyon volcanics (tenta­

tive name). The Perrys Hollow fanglomerate (tentative name) is

separated from the Laramide clastic sediments, because it is be­

lieved to be of post-Laramide origin. PREVIOUS INVESTIGATIONS

For over 100 years references to clastic rocks of Laramide- age have appeared in the literature. Owing to similarities between formations and differences within the same formation coupled with minimal fossil content, an expectable confusion in nomenclature has arisen. Many names have since fallen into disuse. A chrono­ logical review of the development of the nomenclature is shown in

Figure 1 in the hope of resolving the understandable confusion.

In 1869 Hayden (p. 90) named the Wasatch Group from exposures in southwesternWyoming and Echo Canyon and Weber

Canyon in Utah.

Veatch (1907) divided the Wasatch Group into three format­ ions, the Almy, Fowkes and Knight. He considered the Wasatch

Group to be conformably underlain by the lower Eocene Evanston

Formation and overlain by the Green River and Bridger Formations.

Eardley (1944) retained much of the terminology initiated by Veatch (1907). He recognized the three formations of the

Wasatch Group but divided the Almy into two members; the lower was called the Pulpit Conglomerate and the upper the Saw Mill

Conglomerate. In addition to the two subdivisions of the Almy

Conglomerate, Eardley introduced names for units above and I

rtAYDEN VEATCH EARDLEY WILLIAMS 8 EARDLEY ORIEL ORIEL a _ MULLENS NELSON GENERAL SALT LAKE 1907 1944 MAOSEN 1959 1962 TRACY 1970 1971 1971 SECTION AREA 1669 1959

HOLLOW mcioucm SALT

LAKE NORWOOO TUFF NORWOOO

GROUP TUFF BRIDGER FORMATION

or < t- u

Figure 1. History of the stratigraphic nomenclature. Dotted areas are those lithologic units originally part of Hayden's Wasatch Group. below the Wasatch Group; the Upper Cretaceous or lower Paleocene

Henefer Formation and the Oligocene volcanic formation the Norwo­ od Tuff.

Identification of significant fossils enabled Williams and

Madsen (1959) to reorganize and date much of the Late Cretaceous of the Wasatch Hinterland. Beds that had previously been referred to as the Hilliard and Adaville Formations they named the Wanship

Formation (Niobraran). Madsen's discovery of a Cretaceous fauna in what had been called Almy resulted in the application of a new name - Echo Canyon Conglomerate (Montanan). The reorganized

Wasatch Group now consisted of only two formations, the Fowkes and the Knight.

Eardley (1959) reinvestigated the work done by Veatch

(1907) and uncovered a major error. Veatch considered the Fowkes to lie between the Almy (now the Echo Canyon Conglomerate) and

Knight Formations and pointed to the hills northwest of Evanston,

Wyoming to confirm his theory. Eardley found that Veatch had overlooked the normal faulting in the area; in fact, the Fowkes was younger than both the Almy (Echo Canyon Conglomerate) and

Knight Formations. He concluded that the Fowkes Formation and

No rwood Tuff were equivalent and discontinued using the name Nor­ wood Tuff, substituting for it the older Fowkes Formation. The

original Wasatch Group of Veatch (1907) had now been reduced to 7 one formation, the Knight. Justifiably then, the Wasatch Group was reduced to formation status because lithologic units within it rang­ ing in age from Cretaceous to Oligocene had been removed and re­ named as separate formations. Though the name Knight was used for the state geologic map (Stokes and Madsen, 1961), usage has favored return to the term Wasatch Formation.

In his work in southwestern Wyoming, Oriel (1962) succeeded in subdividing the Wasatch Formation into five members: the West­ ern Conglomerate, Upper Tongue, New Fork Tongue, LaBarge

Member aixd Chappo Member. Oriel considered the previous names,

Almy and Knight, to be inapplicable to southwestern Wyoming.

As a result of their work Oriel and Tracy (1970)established several members each for the Evanston, Wasatch and Fowkes

Formations (see Figure 1).

Mullens (1971) combined the Wyoming terminology with the

relevant Utah nomenclature for stratigraphic units in the Wasatch

Hinterland of Utah. He recognized the Echo Canyon Conglomerate of Williams and Madsen (1959) as Cretaceous, but dropped the

Knight (Eocene) Formation (Stokes and Madsen, 1961) and sub­

stituted for it two formations: the Evanston Formation (Late Cret­

aceous and Paleocene) and the Wasatch Formation (Paleocene and

Eocene). He noted that the two were separated by a previously

unrecognized unconformity in the Lost Creek and Echo Canyon 8 areas. Mullens considered the Almy nomenclature as "peripheral facies" and the Knight as "basinal facies" of the Wasatch Formation.

Because neither of these facies had been separated in Utah he pre- fered the use of Wasatch Formation.

Nelson (1971), through paleontological studies in Utah and

Wyoming, concluded that the Fowkes Formation and the Norwood

Tuff are two separate units. The Norwood Tuff of the East Canyon,

Morgan Valley, and Huntsville areas is late Eocene to early

Oligocene in age and the Fowkes Formation of the Utah - Wyoming

border is late middle Eocene in age. STRATIGRAPHY AND LITHOLOGY

As presented in this report, the work of the writer has tended to confirm the conclusions of Mullens (1971) and Nelson

(1971) who recognized the following formations in the Wasatch

Hinterland: Echo Canyon Conglomerate (Upper Cretaceous),

Evanston Formation (Upper Cretaceous to Paleocene), Wasatch

Formation (lower to middle Eocene? ), Fowkes Formation (late

Eocene) and Norwood Tuff (late Eocene and Oligocene). Figure 2 shows approximately the basins in which these formation were deposited. The following lithologic descriptions will point out many of the similarities and differences found in these molasse- type deposits. Figure 3 is intended to clarify the stratigraphic and facies relationships presented. 10

igure 2. Estimated basins of deposition in the Wasatch Hinterland NORWOOD TIM P UNCONFOISMI TY I'OWKKS FORMATION LOCAL UNCONfOHMITV T» GREEN RIVF.R FORMATION Iwsm WASATCH I'ORMATION, EASTERN SANDSTONF.-MUDSTONE FACIES I'wc WASATCH FORMATION, WESTERN CONGLOMERATE l-ACIES LOCAL UNCONFORMITY lev CITY CREEK CANYON VOLCANICS

TKe IVANSTON I ORMATION LOCAL UNCONFORMITY Kec ECHO CANYON CONGLOMERATE ] 2

ECHO CANYON CONGLOMERATE

History and Age

The Echo Canyon Conglomerate was named by Williams and

Madsen (1959) from exposures near the mouth of Echo Canyon.

Mullens (1971) defined the type section as the exposures in sections

18, 19 and 30, T. 3N. , R. 5E. , Summit County, Utah (see Plate 1).

Fossil evidence collected by Madsen (1959) indicates a Late Creta­ ceous possibly Montanan age for the formation-

Lithology

The Echo Canyon Conglomerate ranges in thickness from

approximately 3100 feet at the type locality to 1400 feet near

Croydon, Utah (Mullens, 1971). Cementation by calcium carbonate

and iron oxide has made this unit resistant to weathering so that

it tends to form bold cliffs at most exposures.

The formation is a red or reddish brown, framework (clasts

are touching each other, see Pettijohn, 1957) polymictic conglomer­

ate, composed of a variety of pebbles, cobbles and boulders (up to

15 feet in diameter) of the Precambrian (? ), Paleozoic and Mesoz-

oic formations of the Wasatch Mountains area. In the eastern

exposures, near the town of Echo, Utah, the conglomerate consists 13 of 60% pebble to small boulder size subangular to subrounded clasts of limestone, sandstone and siltstone (Mullens, 1971).

Interbedded with the conglomerates are lenses of sandstone, silt- stone and mudstone. Fossils from the finer sediments indicate a near shore environment in the basin of deposition (Madsen, 1 959)•

Stream channel deposits were noted in the exposures of the Echo

Canyon Conglomerate near East Canyon and Croydon. The average

size of the boulders increases from east to west; in the west lime­

stone boulders 15 feet in diameter are common. Mullens (1971) also found the Echo Canyon Conglomerate near East Canyon to be much coarser than in Echo Canyon and noted a westward enrichment in limestone clasts within the conglomerate.

Lithologically the Echo Canyon Conglomerate can be dis­ tinguished from the overlying conglomerates of the Evanston and

Wasatch Formations by the larger percentages of Paleozoic lime­

stone clasts, and lower percentages of quartzite and Precambrian

clasts. In addition, the Echo Canyon generally is more thoroughly

cemented than the overlying formations and forms bold outcrops

of deep red or white framework conglomerate.

Location and Stratigraphy

All locations that reveal the lower contact of the Echo

Canyon Conglomerate show it to be conformable on the Wanship

Formation. The upper contact with the Evanston Formation is 14 either conformable or unconformable depending on locality.

The original lateral extent of the formation is not known.

Granger and Sharp (1952) mapped the Echo Canyon Formation

farther south than shown in Figure 2. In T. IN. , R. 2 and 3E. (see

Plate 1) Granger and Sharp show the Wasatch Formation to overlie

unconformably the Echo Canyon Conglomerate and stated that

Precambrian clasts are to be found in the overlying Wasatch

Formation, but were absent in the Echo Canyon Conglomerate.

In reviewing the area for this report, the author found a low angle

fault in place of Granger and Sharp's unconformity. The pebble

count for the locality (see Table 1) shows the composition of the

lower conglomerate to be almost equal to that of the upper, both

containing Precambrian material. For these reasons, and the

fact that there is no Evanston Formation present separating the

formations, the outcrops are believed to be basal Wasatch Form­

ation and not the Echo Canyon Conglomerate as proposed by Granger

and Sharp (1952).

Conglomerate outcrops on the Salt Lake City Salient also

were mapped as, "Wanship-Echo Canyon Conglomerate undif­

ferentiated, " by Stokes and Madsen (1961). These exposures are

beli eved to be the Evanston Formation and will be discussed later

under that formation. 1 5

EVANSTON FORMATION

fa story and Age

The Evanston Formation was named by Veatch (1907) from exposures near Evanston, Wyoming. Oriel and Tracy divided the formation as it occurs in Fossil Basin into three members (see

Figure 1). Mullens (1971) carried the name into northeastern Utah and correlated it with Tertiary lithologic units previously regarded as the Knight Formation, Almy Formation and Saw Mill Conglomer­ ate. The Evanston Formation, because of its stratigraphic position and fossil pollen content is believed to be latest Cretaceous and

Paleocene in age (Mullens, 1971, p. D13)

Lithology

In northeastern Utah the fluvial Evanston Formation consists of a lower conglomerate up to 600 feet thick and an upper, finer grained member up to 1000 feet thick (Mullens, 1971). The lower

conglomerate is a tan, light gray, red or reddish brown, framework,

polymictic conglomerate. Clasts reach a diameter of 2 feet and are

subangular to rounded with most being subspherical. Generally, beds contain more than 7 5% quartzite with minor amounts of lime­

stone, sandstone and chert. A few minor beds at the mouth of 16

Trail Creek (see Plate 1) were observed to be 95%+ white quartzite.

Limestone pebbles and cobbles are present, but are generally

smaller than quartzite clasts within the same bed- A distinguishing

characteristic of the entire Evanston Formation is the abundance

of limonitic iron in the form of nodules, and iron banding ( see

Figure 4). The exposures of conglomerate in Trail Creek contain

beds of cross-stratified sandstone and thin, up to 2 inch thick

coal seams. The Trail Creek outcrops are deceiving; at first they

appear to resemble the Wasatch conglomerates but upon closer

inspection show abundant iron nodules, coal and coloration charact­

eristics typical of the Evanston Formation.

As pointed out by Mullens (1971), the thickness of the lower

conglomerate is highly variable and changes abruptly over very

short distances. The lower conglomerate at the mouths of Francis

and Trail Creek Canyons is 500-600 feet thick, but just to the north

in Killfoil Canyon the conglomerate is absent. Good exposures of

the lower conglomerate are also found in lower Echo Canyon and

in Chalk Creek near Pinecliff Resort and in the Salt Lake City

Salient where limestone clasts are dominant.

In Killfoil Canyon the Evanston Formation consists of silt-

stone, sandstone, mudstone and minor amounts of conglomerate

resting unconformably on Jurassic beds. Fluvial, cros s-stratified,

micaceous, tan channel sandstone is the most abundant rock type.

Fossil root fragments were observed in some of the sandstone beds. 17

Figure 4. Iron nodule from the Evanston Formation, SE sec. 4- T.2N.-R.3E., Morgan County, Utah. 18

In addition to the sandstone, gray mudstone and pebble conglomerate form a considerable portion of the approximately 1000 feet of

section.

In Lost Creek and Toone Canyons the upper unit was mined

for coal (Doelling, 1972). Similar to the basal conglomerate, iron

nodules of pyrite are also common in the upper fine grained unit,

suggesting a reducing environment. Mullens (1971) stated that he

believed the prominent brown color was caused by the oxidation of

the reduced iron.

The Evanston Formation on the Salt Lake City Salient

consists of a basal white conglomerate overlain by red and tan

fluvial sandstone, siltstone, conglomerate and light gray lacustrine

limestone.

One of the characteristics that distinguishes the Evanston

Formation from other similar deposits is the combination of a

lower conglomerate and an upper siltstone-sandstone unit. Where

only one of these units is present recognition is made more dif­

ficult, but the presence of the typical tan or brown, sandstone and

abundant iron nodules often helps. Conglomerate beds in the

Evanston tend to contain clasts more spherical in shape than the

other conglomerates and normally have a higher percentage of

quartzite fragments. The sphericity and high percentage of quart­

zite are not solely diagnostic of the Evanston and should be used

only in conjunction with the other characteristics. The most 19 positive identification is made when coal is present.

Location and Stratigraphy

The Evanston Formation rests unconformably on Mesozoic or Paleozoic rocks or conformably upon the Echo Canyon Congl­ omerate. It also lies conformably or unconformably beneath the

Wasatch Formation or City Creek Canyon volcanics.

In the Wasatch Hinterland, the Evanston Formation is

exposed over a much larger area than the Echo Canyon Conglom­

erate (see Figure 2). It has been recognized in the Causey Dam

Quadrangle, and probably extends even farther north. The southern­

most exposures occur in Chalk Creek along the northern Flank of the

Uinta Mountains. Mapping of the Evanston Formation in Chalk

Creek reveals that the basal Evanston conglomerate is much more

extensive than previously believed. .Careful mapping is especially

needed in this area.

Exposures of conglomerate, sandstone, siltstone and lime­

stone which unconformably overlie Paleozoic limestone on the Salt

Lake City Salient are also correlated with the Evanston Formation.

The clastic sediments which underlie the City Creek Canyon

volcanics (see Figure 3) on the Salt Lake City Salient are both

lithologically typical and atypical of tlae Evanston Formation.

Here the normal basal conglomerate is present and contains the

characteristic iron nodules, but it is atypical being unusually rich 20 in limestone clasts, well cemented and light gray. Overlying the basal conglomerate are red sandstone, siltstone, conglomerate and dense, light gray limestone. These beds comply with the vertical upward fining of the normal Evanston Formation, but color

characteristics and bedding are more characteristic of the Wasatch

Formation. The major reasons for assigning both of these units to

the Evanston Formation are the early Eocene K/Ar dates for the

overlying City Creek Canyon volcanics and the angular unconformity

between the Evanston Formation and the Wasatch Formation (see

Figure 5). The possibility cannot be ruled out that both the unconfor­

mity and the City Creek Canyon volcanics were created during

'Wasatch" time. If this were the case, the red beds now assigned

to the Evanston Formation would be Wasatch Formation. r

21

Figure 5. Unconformity between the Wasatch and Evanston Formations as they are separated by the City Creek Canyon volcanics in the Salt Lake City Salient. 22

CITY CREEK CANYON VOLCANICS

History and Age

Historically, the City Creek Canyon volcanics (tentative name) were first recognized by Granger and Sharp (1952, p. 16).

They identified the "... 800 feet of poorly consolidated red sand­ stone, sandy limestone and water-laid tuff ..." as the Fowkes

Formation (Fowkes Formation as defined by Eardley, (1944, p. 844).

The subsequent redefinition of the Fowkes Formation by Eardley

(1959) and by Nelson (1971) makes this correlation incorrect. The pyroclastic andesite breccias which form the upper unit of the

City Creek Canyon volcanics were mapped by Stokes (1963) and

Marsell and Threet (I960) as Tertiary volcanics. Detailed sec­ tions of the volcanics are to be included in a report on the Salt.

Lake City Salient being prepared by Callaghan, Goeltz and Mann,

in which it is expected that they will be formally named the City

Creek Canyon volcanics.

The City Creek Canyon volcanics lie in a strategic position

for correlating the underlying and overlying formations and the

angular unconformities which form the contacts. For these i

reasons the age of the formation is critical to understanding the

geology of the area. AMOCO Production Company very kindly 23 undertook to secure K/Ar age determinations of two samples

submitted by the writer* The age determinations were made by

Krueger Enterprises, Inc. , Geochron Laboratories Division, who

reported the following results:

Sample No. 6: Amphibole porphyry Location: NWNE Sec 21-T. IN. - R. IE. , Salt Lake County, Utah Material Analyzed: Amphibole Concentrate Date: 55.7- 2.6 m. y. (Wasatchian)

Sample No. 11: Biotite Amphibole porphyry Location: NENW Sec. 12-T. IN. - R. 1 W. , Davis County, Utah Material Analyzed: Biotite concentrate: 90% pure, remain­ der Amphibole Date: 50. 9-2. 0 m. y. (Wasatchian)

The early Eocene (Wasatchian) date assigned to the City Creek

Canyon volcanics makes them older than other nearby volcanics,

for a comparison refer to Table 3.

Lithology

The City Creek Canyon volcanics consist of two units, a

lower, 600 feet thick, waterlaid unit of tuffaceous materials now

largely altered to montmorillonite clay and an upper, 300 feet

thick unit, of a purplish andesitic volcanic breccia. The samples

selected for age dating came from blocks of the upper andesite

breccia. The lower unit (see Figure 6) rests on the red sandstone

and siltstone beds of the Evanston Formation. At Victory Road

Reservoir site, northwest of the State Capitol Building, the lower

beds of the waterlaid unit are colored red from derived material. 24 25

The waterlaid beds prior to argillation appear to have been assem­ blages dominated by glass fragments with variable small amounts of crystalline biotite and feldspar. Some large fragments (up to

2 inches in diameter) of altered pumice occur in the fine grained units. A bed of cross-stratified grit containing rounded sand to

pebble size fragments (up to 3/4 inch in diameter) was noted.

Some beds are firmly cemented with calcium carbonate. Most of the material is soft and clayey on the weathered surface and the

entire lower unit tends to have a low resistance to weathering

and erosion.

The upper unit is an assemblage of blocks, mainly small

boulder size, of hornblende andesite in a matrix of an do sit e and

smaller fragments- The degree of stratification varies- Some

of the beds are quite massive. The mineral assemblages in the

blocks are for the most part unaltered. Some rounded limestone

and quartzite pebbles and boulders were noted in the top and base

of the unit.

Location and Stratigraphy

The City Creek Canyon volcanics are known only on the

Salt Lake City Salient although they probably extend at depth

under the present Great Salt Lake Valley (see Figure 2). The

stratigraphic relationships are best show^n in Figure 3, where the

volcanics overlie approximately 1100 feet of the Evanston Forma- tion and underlie at least 2 000 feet of the Wasatch Formation- 27

WASATCH FORMATION

History and Age

Since its introduction by Hayden in 1869 as a group name,

the Wasatch has had a varied usage. Early writers used the term for any red conglomerate and sandstone from New Mexico

to Montana suspected of being early Tertiary in age- Justifiably

then, the term has been criticized as a "catch-all", many have

advocated dropping it entirely. More recent investigations such

as those by Spieker in central Utah or Oriel & Tracy in Wyoming

or Mullens in northern Utah have refined the usage of the term

but have not advocated dropping it from the nomenclature. Instead

the erroneous subdivisions of the Wasatch Group have been

removed or reorganized- Such is the case with the Wasatch term­

inology of the Wasatch Hinterland. In the subsurface and surface

geology of the Uinta Basin and Southwestern Wyoming the Wasatch

Formation is found to underlie and intertongue with the lacustrine

beds of the Green River Formation. The correlated equivalent of

these Wasatch beds in the Hinterland should also be termed Was­

atch, the name being justified by the history of the "Wasatch"

nomenclature in the literature and the fades relationships they i have with the Green River Formation. 28

The only remaining problem then, is to determine what should be done with the formational names of the Wasatch Group.

Oriel & Tracy (1970) believed any attempt at recovering the ori­ ginal Knight and Almy names would be useful only to express facies relationships, the coarser grained peripheral facies being the Almy and the finer grained basinal being the Knight. This seems inadvisable, in that any attempt to reinstate old terms from the already confused literature, and applying them to litho- logic units different from the original, would only create additional chaos. The author believes the facies of the Wasatch Formation are best treated using descriptive rock names, i. e. the western conglomerate and eastern sandstone-mudstone facies.

Fossil content of the Wasatch Formation in the Wasatch Hin­ terland has so far proved insufficient to provide an adequate age.

Radiometric dating of the overlying Norwood Tuff in Morgan

Valley as 36. 0 to 38. 3 m. y. (latest Eocene or earliest Oligocene,

Table 3 ) has established an upper limit of age. Oriel and Tracy

(1970) obtained a date of 47. 7 m. y. (late Eocene) for the Bulldog

Hollow member of the Fowkes Formation which overlies the

Wasatch.

That portion of the Wasatch Formation preserved in the

Salt Lake City Salient overlies unconformably the City Creek

Canyon volcanics for which ages of 50. 9 and 55. 7 (early Eocene)

were obtained (see Table 3). Blocks of th.e volcanic rock were 29 found in the base of the Wasatch. Thus it seems reasonable to

conclude that the deposition of the Wasatch Formation of the Salt

Lake City Salient is limited to the early Eocene. Because of its large lateral and vertical extent the Wasatch Formation of the

Hinterland may also contain upper Paleocene deposits although the majority of the formation is believed to be early to middle

Eocene (? ) in age.

Lithology

As a molasse type deposit the Wasatch accumulated in an

extensive basin or group of basins in which variation in degree of

subsidence with respect to source areas favored notable variations

of thickness and facies. The western exposures contain a large

percentage of red, cobble and boulder conglomerates. In the

eastern Hinterland these conglomerates grade into brightly colored

variegated sandstone, siltstone and shale. In this report two

facies are named,the western conglomerate facies and the eastern

sandstone-mud stone facies (see Figure 3). Because of the distinc­

tive characteristics of each of the facies, they are here treated

separately.

Western Conglomerate Facies

The western conglomerate facies of the Wasatch Formation

reaches over 5000 feet thick and is dominated by pebble, cobble 30 and boulder conglomerate interbedded with varying amounts of

sandstone, siltstone, mudstone and oncolitic limestone. Most beds are red, although purplish-red, yellow, orange, greenish-

red, white, gray and grayish-red layers may be found. East

Canyon from East Canyon Reservoir to Morgan Valley offers the best exposures and is here designated as the type locality for the western conglomerate facies. A section was measured at this

locality (see Appendix). A columnar section (see Figure 7)

produced from the measured section in East Canyon shows the

western conglomerate facies to be approximately 50-60% conglo­

meratic rocks at this location.

Throughout the Hinterland, the conglomerate beds of the

western conglomerate facies show a great range in clast size,

bed thickness, composition and ratio of clasts to matrix. In

general, the conglomerates are thick to massively bedded up to

200 feet, red, polymictic, and framework type. The pebbles,

cobbles and boulders, (up to 15 feet in diameter, see Figure 8)

are composed of quartzite, sandstone, limestone, chert, siltstone,

schist, pegmatite and conglomerate. As will be discussed later,

the pebble counts show that the formation from locality to locality,

varies greatly in the percentages of pebble lithologies. Within

individual beds, the largest clasts are generally quartzite and the

limestone, sandstone, chert, siltstone, and schist clasts are

respectively smaller- This size distribution is logically a result 31

litfuiT 7. COLUMNAR SECTION OF THE WESTERN CONGLOMERATE FACIES OF THE WASATCH FORMATION

4468 I 1 IT MEASURED 500+ ITET MISSING EROSION SURFACE

OUTCROP COVCRfD INF ERRED F ROM SOIL

C3

BOULDER CONGLOMERATE • 0-- O' o. •

COBBLE CONGLOMERATE

PEBBLE CONGLOMERATE

i : is . n ONCOLITIC LIMESTONE

CLAYSTONI SANDY SILTSTONE SANDS I ONI

rVWVW

I 32

Figure 8. Large boulder in the Wasatch Formation, Boulder is approximately 7 feet across. 33 of differing resistances to abrasion during transportation.

Where larger clasts are dominant, they are packed in such a way as to produce an imbricated framework (Pettijohn, 1947) with the matrix material occupying the interstices (see Figure 9)«

The matrix material is extremely hetergeneous. Particle size ranges from clay to granule; sand in the matrix ranges from very fine to very coarse, angular to subrounded, and is poorly sorted.

Individual sand or granule size particles are rock fragments of quartz, chert, limestone, and dolomite and minor amounts of chalcedony, claystone and siltstone (see Figure 10). The typical matrix consists of approximately equal parts of sand and silt size particles.

The cement throughout the Wasatch Formation is calcium carbonate. The characteristic brick red color is due to secondary iron oxide staining of the constituent particles and matrix. In some places, clasts have retained staining characteristics of previous conglomerate source rocks (? ). Some beds lack the characteristic red staining, in these the matrix tends to be a poorly cemented light gray, friable, silty sandstone.

Interbedded with the conglomerate beds are sandstone and mudstone beds which greatly resemble the conglomerate matrix

(see Figure 11). In the western conglomerate facies, the propor­ tion of finer grained rocks in the section varies greatly from one

locality to another and can constitute a large percentage of the 34

Figure 9* Framework type conglomerate from the Wasatch Formation. X 1/2.

Figure 10. Photomicrograph of the Wasatch Formation. Arrow points to a rounded sandstone fragment with stained boarder. Much of the dark material is chert. X nicols, X 25.

)

3 6 total volume of the formation. At the type locality in East Canyon, they constitute about 40% of the total section. The blankets, wedges and lenses of fine-grained rocks are dominated by red, orange and gray sandstone with siltstone and mudstone respec­ tively less abundant. The fine-grained rocks vary more in color than do the conglomerate lenses with which they are interbedded.

The typical red color of the conglomerate and sandstone gives way in some mudstone to intense hues of purple, reddish-purple or yellowish-green.

Sorting and cementation is generally poor in the fine-grained rocks and they appear to have been deposited by streams and during the waning stages of flooding. This contrasts with the conglomerates which probably were deposited during the maximum flood stage. Because of the rhythmic or cyclical type of deposi­ tion, the large volume of source material and the relatively short distance of transportation, sorting is very poor. The depositional environment for the western conglomerate facies created the following primary sedimentary structures in the fine-grained

rocks: channels (Figure 12), festoon cross-stratification and poorly preserved ripple marks.

The exposures of the western conglomerate facies from

Coalville to Morgan Valley contain lenses of oncolitic limestone

up to 1 5 feet thick. The lateral extent of these lenses is observed

to be less than a mile. Oncolitic limestone is composed of indiv- Figure 12. Festoon cross-stratification in the Wasatch Formation. Note that the sandstone bed is cut by channels filled with conglomerate. 38 idual limestone balls ranging in size up to about 1 foot in diameter

(see Figure 13). Oncolites are concentrically banded and round but are not necessarily spherical in shape (see Figure 14). The cores of individual oncolites are detrital grains, or shell frag­ ments or gastropod shells (see Figures 15 and 16). The origin of the oncolites is uncertain. They are believed to be algal in

origin, probably resulting from algal growth in small shallow lakes or ponds. Mullens (1971) and Oriel and Tracy (1970) re­

ferred to the oncolites as pisoliths. Because the author believes them to be algal in origin and probably mobile during formation,

oncolite is used rather than the non-algal pisolith or the immobile

stromatolite.

Oncolitic limestone beds are the most resistant ridge formers

in the western conglomerate facies. These silty limestones are

tan when fresh, but weather to gray or absorb the predominant red

iron oxide color- Individual oncolites are not strictly confined to

the limestone beds, but are found several feet above and below

in the adjacent conglomerate, sandstone and mudstone-

The western conglomerate facies can be easily confused

with the coarse clastic sediments of the Echo Canyon Conglomerate

or Evanston Formation. Generally though, the conglomerate

beds of the Wasatch Formation are not as well cemented as the

Echo Canyon Conglomerate, contain more interbedded fine-grained

mudstone than either the Evanston or Echo Canyon and contain Figure 13. Large oncolites in limestone from the western conglom­ erate facies of the Wasatch Formation in East Canyon, sec 4 - T.2N.-R. 3E. , Morgan County, Utah. Figure 15. Photomicrograph of a probable shell fragment forming the nucleus of an oncolite. X nicols, X 25. 41

Figure 16. Photomicrograph of a gastropod forming the nucleus of an oncolite. X nicols, X 25. 42 oncolitic limestone not observed in either of the other two forma­ tions*

The western conglomerate facies yielded scarce, preserved fossils- The most common are unidentified root fragments, gen­ erally found in sandstone and siltstone beds (see Figure 17).

Gastropods were collected from both conglomerate and oncolitic limestone beds and represent several types, one of which is believed to be the genus Goniobasis (see Figure .18). Algal re­ mains, shell fragments and borings were collected, but the poor preservation did not permit identification.

Numerous fossils derived from older rocks were collected, the most common are invertebrates from the Park City Forma­ tion (see Figure I9)«

Eastern Sandstone - Mudstone Facies

The eastern sandstone - mudstone facies was originally

described by Veatch (1907, his Knight Formation) from beds near

Wahsatch as "reddish - yellow sandy clay and irregular sandstone

beds". Besides the reddish - yellow sandy clays, the facies

contains red and purple mudstone and tan, red, yellow, gray and

white sandstone and occasional, thin, pebble conglomerate beds.

Most of the sandstone beds have large scale cross-stratification.

Conglomerate beds are composed of pebble and cobble size clasts

°f pink, red, yellow, orange, purple and green quartzite, gray and 43

Figure 18. Photomicrograph of possible Goniobasis (? ) from the western conglomerate facies. X nicols, X 25. 44

Figure 19* Fossiliferous limestone cobble of the Park City Form­ ation found within the western conglomerate facies of the Wasatch Formation. X 1/2. black chert and minor amounts of sandstone and siltstone pebbies.

Individual clasts are well rounded and more nearly spherical than those found in the western conglomerate facies.

As in the conglomerate facies, calcium carbonate is the cementing agent for the fine grained rocks. There is consider­ able variation, but cementation is generally weak. Beds are generally thinner than in the western facies, but reach massive proportions in some localities.

The eastern sandstone-mudstone facies is easily recognized.

The small quantities of conglomerate and the brightly colored mudstone distinguishes it from both the Evanston Formation and the western conglomerate facies of the Wasatch Formation.

A fossil turtle found by the writer in the sandstone-mudstone

facies in SESW section 26, T.4N. , R. 8E. , Summit County, Utah,

was tentatively identified by Dennis M. Bramble (personal commu­

nication) as Baena arenosa (? ) or Chisternon undatum (?) (see

Figure 20). The type of sedimentary environment in which the

fossil was found caused Bramble to prefer Baena arenosa as the

species designation. The fossil evidence is quite meager in the

sandstone-mudstone facies, but the facies is believed to be lower

and middle Eocene (?) in age, roughly equivalent to the Green

River Formation with which it intertongues- Figure 20. Inner cast of a turtle shell (Baena arenosa or Chisternon undatum) showing vertebrae. 47

FOWKES FORMATION

The Fowkes Formation, named by Veatch (1907) from exposures on the Fowkes ranch 9 miles from Evanston, Wyoming

(Keroher, 1966, p. 1409) is one of three sedimentary units containing volcanic material (see Figure 21) in the Wasatch Hin- terland. Each has now been dated radiometrically (see Table 3) and as such has provided upper and lower age limits for the

Wasatch Formation. Veatch confused the position of the forma­ tion and this in turn led Eardley (1944) to equate the Fowkes with the Norwood although the two can be separated geographically.

Oriel and Tracy divided the Fowkes into three members (see Figure

1) and obtained a radiometric age of 47. 7-1.5 m. y. (middle

Eocene) for samples from the Bulldog Hollow Member. This differs significantly from the age of the Norwood (36 to 38. 3 m. y. ) and the City Creek volcanics (50. 9 - 55. 7 m. y. ). Nelson (1971)

states that,

The Fowkes consists of 100^ - 3000- feet of gray to light green tan to buff, red to lavender, and white, ashy calcareous mudstone and claystone, and interbedded buff to white, tuffaceous, calcareous sandstone.

and attributed a late middle Eocene age to the formation. The

Writer made no new investigation of the Fowkes Formation. FIGURE 21. TERTIARY VOLCANICS OF THE WASATCH HINTERLAND 49

NORWOOD TUFF

The Norwood Tuff named by Eardley, (1 944) crops out exten­ sively in Morgan Valley and at the east side of East Canyon

Reservoir in the center of the Hinterland (Figure 21) where it unconformably overlies the Wasatch Formation. Fossil evidence and radiometric dating place the formation as latest Eocene or earliest Oligocene. The following dates were obtained by Evernden and others (1964, p. 145-198):

KA 825 Mineral: Sanidine

6 Date: K=8. 13%, A40 at=54%, t=37.4 X 10 yrs. North American Land-Mammal Age: Duchesnean

KA 826 Mine ral: Biotite

at 6 Date: K=5. 54%, A40 = 74%, t=37. 5 X 10 yrs. North American Land-Mammal Age: Duchesnean

KA 827 Mineral: Glass

at 6 Date: K=4. 78, A4Q =19%, t=36. 0 X 1 0 yrs.

AMOCO Production Company very kindly secured from

Geochron Laboratories a radiometric age for a sample taken by the writer of Norwood Tuff near East Canyon Reservoir* The

results obtained by Geochron Laboratories are as follows:

Sample No. 1 Location: SWNW 11-T.2N., R. 3E. , Morgan County, Utah, north side of road 50 Mineral Analyzed: Biotite concentrate

Date: 38. 3-1.5 m. y. latest Eocene or earliest Oligocene

The Norwood Tuff consists of 5000- feet of pink, gray, white, purple, and tan tuffaceous sandstone, mudstone, conglo­ merate, pyroclastic rocks, volcanic breccia and siliceous lime­ stone. Much of the formation is water-laid and has distinct bedding and cross-stratification (see Figure 22). Thick, siliceous lime­

stone beds in Hobble Creek and along the eastern slope of the

"Wasatch Mountains in western Morgan Valley indicate the influence

of freshwater lakes, during deposition of the formation. The

pyroclastic rocks and congldmerate are highly variable in compo­

sition, but andesite especially hornblende andesite porphyry

fragments are common in the sedimentary volcanic units. Nelson

(1971) concluded from fossil evidence that a warm climate accom­

panied the deposition of the Norwood Tuff. 51

Figure 22. Outcrop of Norwood Tuff near East Canyon Reservoir* Small stream channels are filled with rounded cobbles of andesite. 52

PERCYS HOLLOW FANGLOMERATE

In the Salt Lake City Salient at the northeast side of Salt

Lake City the Wasatch Formation is overlain unconformably by

several hundred feet of beds consisting for the most part of

angular fragments of limestone and other rocks derived from

exposed Paleozoic limestone and quartzite formations or debris

from the Wasatch Formation. Rounded gravels and possibly some

silt or clay were noted in section 29 (Fig* 23) and a tuff bed with

fresh glass shards was exposed briefly in a house excavation in

section 33 (Figure 23). In section 22 (Figure 23) beds of this

formation lie across the projected position of the fault between

the Wasatch Formation and Paleozoic formations, apparently

without dislocation. Nevertheless, the formation is faulted and

tilted (Figure 24). Some outcrops in gravel pits on the north side

of Bountiful may be part of this formation. Exposures are notched

by terraces of Lake Bonneville.

This formation was included in the Knight Formation by

Granger and Sharp (1952) and by Marsell and Threet (I960). On

the state geologic map (Stokes, 1963) it is shown as "Tertiary -

Quaternary undivided". In a forthcoming report by Callaghan,

Goeltz and Mann the formation will be formally named. No definite 53 54

Figure 24. The Perrys Hollow fanglomerate at the mouth of Perrys Hollow.

Figure 25. Photomicrograph of the Perrys Hollow fanglomerate. Note the abundance of angular particles and rare rounded clasts from the Wasatch Formation. X nicols, X 25. 55 evidence of age has as yet been determined beyond the relationships noted above. These would suggest that the Perrys Hollow fanglomer­ ate is the equivalent of some unit in the Salt Lake Group and almost without doubt is of Miocene or Pliocene age. CORRELATION

There is much uncertainty in the correlation of conglomer­ atic units whose ages are poorly understood, and where fossil, evidence is generally lacking. However, some correlation between the Late Cretaceous and early Tertiary beds of the Western Uinta

Basin and similar beds in the Hinterland is possible (see Figure 26).

ECHO CANYON CONGLOMERATE - PRICE RIVER AND BENNION CREEK FORMATION

During the Late Cretaceous the eastward regressing sea gave rise to the fluvial beds of the Price River Formation of

Central Utah. Spieker (1931 p. 44 & 1954, p. 1783) regarded these beds as middle to late Montanan age and placed them above the Castlegate Sandstone, which he believed to be deposited in a brackish water environment. The Price River Formation was

restricted by Moussa (1965) who named the upper unconformable

conglomeratic unit the Bennion Creek Formation. From strati-

graphic evidence Moussa deduced the age of the Bennion Creek to be late Montanan to Lancian.

In Echo Canyon, the lithologically similar but thicker Echo

Canyon Conglomerate contains fauna (Madsen, 1959) that also

indicates a regressive near shore environment. To the west, 57

UINTA II A S I N

Figure 26-A Correlation chart for the Wasatch Hinterland and West ern Uinta Basin, from Garvin, 1969* 58

WASATCH H IN T t R LAND-WYOMI NG

Figure 26-B Correlation chart for the Wasatch Hinterland and Western Uinta Basin. 59

near East Canyon, the Echo Canyon boulder conglomerate was deposited in a fluvial environment. The Echo Canyon is of prob­ able Montanan age (Williams & Madsen, 1959, p- 125).

The correlation here made between the Price River and

Bennion Creek Formations and the Echo Canyon Conglomerate is based on the lithologic similarities, limited fossil evidence and the similar environmental changes found within all three forma­ tions •

CURRANT CREEK AND NORTH HORN FORMATIONS - EVANSTON FORMATION

The North Horn Formation was first classified as "Wasatch"

(Spieker and Reeside, 1925, p. 448), but the discovery of dino-

saurian and mammalian fauna established its true age (Spieker,

1946) as spanning from Lancian to middle Paleocene. The forma­

tion contains conglomerate, sandstone, shale and fresh water

limestone. Small thin lenses of lignite are present along with

abundant red staining caused by the oxidation of iron sulfides-

Du ring the deposition of the North Horn Formation occasional

warm, wet periods produced swamps. Reducing environments

may have occured in conjunction with the localized freshwater lakes,

which produced some limestones and oncolites. In some locali­

ties the North Horn contains clasts of volcanic material.

The counterpart to the North Horn in northeastern Utah is 6 0 the Evanston Formation. The Evanston Formation, like the North

Horn, was originally placed as part of the Wasatch (Knight? )

Formation anc| was thought to be Eocene in age. Later study found pollen indicative of Lancian age and gastropods of Paleocene or Eocene age (Mullens, 1971, p. D14-D15 and Trexler, 1966,

p. 58- 59)- Like the North Horn, the Evanston Formation contains

conglomerate, sandstone, mudstone, coal and oxidized iron sul­

fides, although no limestones or oncolites have been found. The

depositional environment of the two formations is remarkably

similar- Both span the Cretaceous - Tertiary age boundary and

have obscure contacts with adjacent formations except where

unconformities are present.

The Currant Creek Formation has not yielded fossils to

verify its age- Garvin (1969) believes it to be Late Cretaceous to

early Eocene in age. Thus,it would roughly correlate in age with

the Evanston and Wasatch Formations of northeastern Utah.

COLTON FORMATION - WASATCH FORMATION

In the western Uinta Basin the Colton Formation is the name

given to the fluvial beds found between the Flagstaff Formation

(Paleocene) and the Green River Formation (Eocene)' The Colton

is considered equivalent to the Wasatch Formation east of Green

River, Utah. The lack of fossils leaves only stratigraphic evi- 61 dence for its age- Spieker (1946, p. 139) believed it to be early

Eocene- The Colton or "Wasatch" of the western Uinta Basin consists of discontinuous lenses of sandstone and siltstone charac

teristic of flood plain deposition. Both the Wasatch and Colton

intertongue with lithologically similar beds of the equivalent and

younger Green River Formation.

The Colton and Wasatch Formations of the Uinta Basin are

here correlated with the Wasatch Formation of the Wasatch Hinte

land. Based on limited fossil evidence and stratigraphic relation

ships and radiometric dating the Wasatch of northeastern Utah is

assigned a late Paleocene to middle Eocene age. PALEOCURRENT STUDY

GENERAL STATEMENT

In order to understand the source area, source rock, and depositional environment of the Wasatch Formation and its stra- tigraphic neighbors, a paleocurrent study was conducted using imbricated pebbles found in beds of the Wasatch Formation, Evan- ston Formation, and the Echo Canyon Conglomerate.

Preliminary observations in the Wasatch Formation showed large scale festoon type cross-stratification common in the sand­ stone beds, pebble, cobble and boulder imbrication in the conglo­ merate beds and rare, poorly developed ripple marks in the silt- stone and mudstone units. The difficulties in using large scale festoon cross-stratification and the rare and poor quality of the ripple marks left only imbrication open for study.

Potter and Pettijohn (1963, p. 3 5) showed in modern fluvial environments a definite preferred orientation or imbrication for disk and ellipsoidal shaped clasts (pebble to boulder size). Up­ stream dip of the clasts generally ranges from 10 to 30 degrees-

There are many factors which may enhance or obscure imbrica­ tion in conglomerates and gravels. Pebble and boulder size

clasts are not generally as well imbricated as cobble size particles 63 and the undercutting and rolling of the boulders by the stream into a variety of random positions. Poor imbrication is common in deposits where the percentage of fine matrix is greater than that of the pebble to boulder size particles. Where a framework

of pebbles, cobbles, or boulders is present, stacking occurs

which increases the chance the particle will lodge in a preferred

orientation. Source rock, sorting, packing density, stream grad­

ient, climate, sphericity, and roundness of the clasts are also

contributing factors to the degree of imbrication in a conglomerate..

PROCEDURE

The large area under consideration and the number of sites

necessary caused some procedural changes from normal data

collecting methods. To save time 20 - 50 strike and dip measure­

ments were taken of cobble size, disk-shaped clasts within conglo­

merate beds showing obvious imbrication at each locality. Where

possible the measurements were taken on outcrop surfaces ori­

ented in different directions. This procedure was necessary

because it was noticed that weathering preferentially removed

imbricated" clasts from outcrop surfaces that were aligned with

the imbrication direction- In like manner, those clasts oriented

perpendicular to the outcrop surface were preferentially preserved

An effort was made to randomly choose disk shaped cobbles 4 to 8

inches in diameter from imbricated beds. (A

Each individual cobble was plotted on a stereonet and cor­ rections were made for tilt of the beds. A compass diagram for each site (see Plate 1) was broken down into 1Z segments of 30 degrees each. The paleocurrent direction indicated by each pebble was individually determined and plotted. The total number of measurements in each 30 degree segment was counted. The compass diagram then afforded a tool for a statistical analysis.

The mean and standard deviation were determined for each dia­ gram (see Plate 1).

RESULTS

Echo Canyon Conglomerate

The combined overall paleocurrent direction for the Echo

Canyon Conglomerate was toward the east-southeast (see Figure

27). The purpose of the few sites measured was to determine if

the Wasatch Formation and Echo Canyon Conglomerate could be

readily distinguished by differences in direction. It soon became

evident that both formations in the Hinterland displayed similar

paleocurrent directions.

Fossil evidence reported by Madsen (1959) indicated an

eastward change from a fluvial to a near shore or brackish water

depositional environment for the Echo Canyon Conglomerate near

Echo City. The measurements taken above Echo City indicated 65

mean equals 15 mean equals 1 one standard deviation equals 11 one standard deviation equals 1 B.

Figure 27. Compass diagram for the Echo Canyon Conglomerate showing a west - northwest to east - southeast current direction. Blackened segments are equal to or greater than two standard deviations above the mean. Dotted segments are equal to or greater than one standard deviation above the mean but less than two standard deviations above the mean. A.) Compiled from the summation of all measurements taken in the Echo Canyon Conglomerate. B.) Compiled using positive standard deviations from each site location. The number in each segment is a summation of the total number of positive standard deviations above the mean. Note that the diagram does not give a direct indication of sample loading. Two diagrams havinq one standard deviation in a particular segment have the same weight as one diagram with two standard deviations in that segment. 66 a southerly paleocurrent flow which cannot be explained except as a local irregularity or a change in paleoenvironments• Not enough

is known, however, to accurately determine the type of environ­

ment or cause of the imbrication at this locality. Between Croy­

don and East Canyon Reservoir the Echo Canyon Conglomerate is

believed to be a fluvial deposit. At these locations an overall

westerly paleocurrent pattern was recorded.

Evanston Formation

No dominant paleocurrent direction was found for the Evan­

ston Formation (see Figure 28). For the few site locations mea­

sured the paleocurrent directions varied radically. Imbrication

at the mouth of Francis Canyon (see #27 Plate 1) indicates a

southwest to northeast paleocurrent direction, those in Echo

Canyon, a northeast to southwest and those in Chalk Creek a

north to south, northwest to southeast, northeast to southwest

and south to north flows.

The large variability of paleocurrent directions in the basal

Evanston Formation (see Figure 28) is interpreted to indicate

that the basal conglomerate of the Evanston Formation is the

result of many small local orogenic disturbances. The variety

of stratigraphic relationships the Evanston Formation has with

underlying formations confirms this theory. Near East Canyon

Reservoir the Evanston Formation lies conformably upon the 67

mean equals 1 one standard deviation equals 6 one standard deviation equals 1

A. B.

Figure 28. Compass diagram for the Evanston Formation showing a random pattern. Blackened segments are equal to or greater than two standard deviations above the mean. Dotted segments are equal to or greater than one standard deviation above the mean but less than two standard deviations above the mean. A.) Compiled from the summation of HI measurements taken in the Evanston Formation. B.) Compiled using positive standard deviations from each site location. The number in each segment is a summation of the total number of positive standard deviations above the mean. Note that the diagram does not give a direct indication of sample loading. Two diagrams having one standard deviation in a particular segment have the same weight as one diagram with two standard deviations in that segment. 68

Echo Canyon and lacks a basal conglomerate; whereas, just to the north in Lost Creek the basal Evanston Formation may be present in some localities and absent in others. Where present it unconformably overlies Mesozoic rocks- The wide variability of paleocurrent directions found in the area of study may indicate that the basal Evanston Formation was deposited into rapidly

subsiding basins receiving sediment from all directions.

According to Mullens (1971), "The abundance of purple,

red and green quartzite clasts in the basal conglomerate of the

Evanston is interpreted to represent a major contribution of

debris transported eastward from the allochthon of the Willard thrust." Pebble counts by Eardley (1944, p. 843) indicate a

probable source area similar to the formations of the northern

Wasatch Range, and not the Uinta Mountains- Because of the

paleocurrent directions, sphericity and composition of the clasts,

and localized rapid thickness variations, the conglomerates of

the Evanston probably were derived locally from reworking of

material from the Echo Canyon Conglomerate and older formations.

Fine-grained material from the allochthons of the western thrusts

may have furnished the clastic material for the upper finer-grained

facies of the Evanston Formation.

Wasatch Formation

A west-northwest to east-southeast flow direction is indi- 69 cated by the imbrication of the Wasatch Formation (see Figure 29)-

The resultant vector diagram shown in Figure 30 provides a smoother representation for the paleocurrent direction than shown on Plate 1. The west-northwest to east-southeast flow direction did not provide an outline of a complete depositional basin. Mea­ surements in the northern sector give easterly directions whereas those in the southern sector record a southeasterly flow. The only valid conclusion is that the source area was somewhere west of the present formation.

Previous observation by Mullens (1971) and Eardley (1944,

1959) also estimated a western source area. They noted the conglomerate facies of the Wasatch Formation thinning eastward and intertonguing with finer-grained rocks. The conglomerates of the eastern sandstone-mudstone facies are quite different from those in the western facies; they contain fewer limestone clasts, more quartzite and chert pebbles and the clasts are more spher­ ical. These observations along with the measured paleocurrent

direction confirm a western source area.

Imbrication in the Wasatch Formation on the western slope

of the Wasatch Mountains on the Salt Lake City Salient gave a

southeast to northwest paleocurrent direction (see Figure 31).

Stokes (personal communication) believes the Wasatch Range may

have been a locally positive area during the deposition of the

Wasatch Formation; if this were the case.it would explain the 70

mean equals 50 mean equals 4 one standard deviation equals 30 one standard deviation equals 5 B.

Figure 29. Compass diagram for the Wasatch Formation of the Wasatch Hinterland showing a west - northwest to east - southeast current direction. Blackened segments are equal to or greater than two standard deviations above the mean. Dotted segments are equal to or greater than one standard deviation above the mean but less than two standard deviations above the mean. A.) Compiled from the summation of all measurements taken in the Wasatch Formation of the Wasatch Hinterland. B.) Compiled using positive standard deviations from each site location. The number in each segment is a summation of the total number of positive standard deviations above the mean. Note that the diagram does not give a direct indication of sample loading. Two diagrams having one standard deviation in a particular segment have the same weight as one diagram with two standard deviations in that segment. Figure 30. PALEOCURRENT VECTOR MAP OF THE WASATCH FORMATION 72

Figure 31. Compass diagram for the Wasatch Formation on the Salt Lake City Salient showing an east - southeast to west - northwest current direction. Blackened segments are equal to or greater than two standard deviations above the mean. Dotted segments are equal to or greater than one standard deviation above the mean but less than two standard deviations above the mean. A. ) Compiled from the summation of all measurements taken in the Wasatch Formation on the Salt Lake City Salient. B.) Compiled using positive standard deviations from each site location. The number in each segment is a summation of the total number of positive standard deviations above the mean. Note that the diagram does not give a direct indication of sample loading. Two diaarams having one standard deviation in a particular segment have the same weight as one diagram with two standard deviations in that segment. westerly flow direction on the Salt Lake City Salient. PEBBLE COUNT

The results of comparative pebble counts are shown in

Table 1. Ten locations were used to botain the percentages shown; eight in the Wasatch Formation, one in the Echo Canyon Conglo­ merate and one in the Evanston Formation (see map for locations).

Because of the work time and difficulty in obtaining values for volume of rock types, the pebbles, cobbles and boulders were systematically counted at each location. No attempt was made to measure the size or determine the volume of each clast. A tape measure was laid across the outcrop and any pebble, cobble or boulder touching the tape was counted as one unit of the appro­ priate rock type. Staining, weathering, and chemical changes due to transportation, lithification or subsequent erosion altered many clasts. This increased the possibility of misrepresenting a color or rock type. Another observation to be kept in mind is that at the site of the count in the Echo Canyon Conglomerate

limestone clasts were generally larger than quartzite clasts, whereas, the converse was true at all other locations in the Was­

atch and Evanston Formations. An actual volume percent (lime­

stone) for the Echo Canyon would probably be close to the 70%

value reported by Mullens (1971). Except for the Echo Canyon, Site locations and percentages A B C D E F G H J K Possible Echo Canyon Evanston source rock Type of clasts Wasatch Formation Conglomerate Formation formations CARBONATE ROCKS gray to blue-gray 0 10.4 15.4 20.7 31.6 31.5 31.9 31.0 36.0 20.6 Maxfield (€), Madison (M), Humbug (M). Twin Creek CE), Ophir (C), Great Blue (M), Descret (M). brown to tan 12.1 0.9 3.3 1.7 5.9 9.3 •Thaynes (E),*Park City (P), Ophir {€), Garden City (O), Jefferson (D). Total Carbonate 0 10.4 15.4 32.8 32.4 34.8 33.6 36.9 45.3 20.6 QUARTZITE white 5.0 20.9 8.6 11.2 6.0 4.3 16.7 16.7 1.3 11.5 Swan Peak (0), *Webcr (P), *Tintic tC), Gartra Grit <"E), Stansbury (D). pink to orange 6.3 4.4 1.9 8.6 8.5 15.2 11.7 8.3 6.7 16.8 •Tintic (€), Gartra Grit (TO. gn-y 23.8 4.4 20.2 18.1 23.1 13.0 5.0 8.3 , 8.0 16.0 •Oquirrh (P), Mineral Fork Tillitc (PC), •Tintic (€), Weber (P), *Park City (P). green to yellow 22-6 7.5 10.6 6.0 0 1.1 3.3 3.6 0 0.8 *Swan Peak (0). red 0 4.4 5.8 1.7 4.3 3.3 1.1 14.7 1.5 •Mutual (PC). purple 10.0 11.9 4.8 0 0 1.1 3.3 0 0 4.6 •Mutual (PC). tan 0 0 0 1.7 11.1 17.4 0 0 0 0 •Tintic (C), Oquirrh (P), Weber (P). - quartzite congl. 2.5 0 0 0 0 0 0 0 0 4.6 •Tintic (€), Gartra Grit (TO. Total Quartzite 70.2 53.5 51.9 47.3 53.0 52.1 43.3 38.0 30.7 55.8 SANDSTONE red 0 4.4 11.5 8.6 6.8 5.4 3.3 2.3 10.7 16.0 Morgan (P), Ankareh fK), Diamond Creek (P), •Nugget ("E), Preuss (JO, Frontier (K). tan 0 0 0 0 0.9 0 1.7 1.1 1.3 1.5 •Park City (P), Frontier (K), *Thaynes (TO, •Oquirrh (?). orange 0 0 0 0 0 0 0 3.3 0 0 •Nugget (T<), Stump (JO. yellow 0 7.5 2.9 1.7 0 0 5.0 3.6 2.7 0 Ankareh (TO. white 0 15.0 0 0 0 0 0 5.6 0 0 Total Sandstone 0 26.9 14.4 10.3 7.7 5.4 10.0 16.2 14.7 17.5 SILTSTONE-SHALE tan 3.8 0 1.9 0 3.5 6.7 0 0 0 0 •Thaynes ("£), Ophir (€). Curtis (JO, Aspen (K). red 1.3 0 4.8 0.9 0 0 0 0 2.7 0 Preuss (JO, Woodside (la). yellow 2.5 1.5 3.8 2.6 0 0 1.7 1.1 0 6.1 Ankareh ("E). ToUi Slts.-Shale 7.6 1.5 10.5 3.5 3.5 6.7 1.7 1.1 2.7 6.1 CHERT 15.0 7.5 7.7 6.1 3.5 1.1 3.3 3.6 6.7 0 Madison (M), Humbug (M), Great Blue (M). SCHIST 7.5 0 0 0 0 0 1.7 0 0 0 Little Willow Series iP€),*Farmington Canyon Complex (P€). PEGMATITE 0 0 0 0 0 0 1.7 0 0 0 •Faxmington Canyon Complex (PC). RED CONGLOMERATE 0 0 0 0 0 0 5.0 3.6 0 0 •Wasatch (E). Table 1. Pebble count in conglomerates of the Wasatch Hinterland. The table gives percentages of clast types and their possible source rock formations. The source rock formations are * if they were identified and followed by the age of the particular formation. For location see plate 1. Note the figures are not volume percent (refer to text). 76 all quartzite percentages probably are lower than the volume measurements would show.

Angular to subrounded fragments of reworked oncolitic limestones, sandstone, siltstone and conglomerate (? ) were observed in the Wasatch Formation in the Morgan Valley area.

These fragments are believed to be rip-ups from underlying beds they are easily distinguished in some cases by the contrast in weathered coloration between the fragment and the lense in which it is found. Large rounded boulders (up to approximately 10 feet in diameter) of a well cemented red conglomerate similar to the

Wasatch Formation or Echo Canyon Conglomerate were observed in the Wasatch Formation in City Creek Canyon. STRUCTURAL HISTORY

GENERAL STATEMENT

Identification of the conglomerates of the Wasatch Hinterland is made easier when it is recognized that the tectonic history of the region is mirrored by these coarse clastic rocks. The sedi­ mentary history contained in the Cretaceous and Early Tertiary formations of Utah records evidence for both the Sevier and Lara- mide Orogenies. According to Armstrong (.1968) the transition from the Sevier to the Laramide Orogeny was gradual. The early phases of the Laramide were characterized by "Sevier" type thrusting, whereas, the later phases were characterized by vertical and compressional "Laramide" type movements (see

Figure .32). The Wasatch Hinterland, besides providing access to sediments shed from Laramide age uplifts, may also contain a record of the Sevier Orogeny in the form of rounded conglomerate boulders (0-12 ft. in diameter) incorporated into the Wasatch form­

ation. Clasts found within the Wasatch Formation frequently show

rounded, stained edges that have survived transport; in some

instances, these are believed to have been derived from older

conglomerates (see Figure 10) shed from high areas uplifted

during the Sevier Orogeny. 78

PLIOCENE

MIOCENE t "71

OUGOCcNE Pi 3*1 EOCENE

PALEOCENE z CLASSIC MAESTRICHTIAN LARAMIDE < OROGENY (Tj z (Tj 6S > > co < cc UJ SEVIER Ko OROGENY > O N a a2. CENCMANIAN diz CD <_> CO t

c o

Z AN D «. OJO OU J crj PI APTIAN CDzZio O •J u BARREMIAN Uo_ >c • H HAUTERIVIAN o o co (of VALANGINiAN aU.J H BERRIASIAPURBECK'ANN 180- • OF CONFORMABLE SEDIMENTATION IN EASTERN CD GREAT BASIN OJO •r-l fa

220- H

230 79

Certainly the Sevier Orogeny, and probably the Laramide began well west of the Hinterland (Armstrong, 1968). However, the

Laramide uplifts not only shed sedimentary debris onto the Hinter­ land, but in the later stages of the Laramide those same sedi­ ments were deformed, (see Table 2). During the early phases of the Laramide Orogeny, northeast-southwest elongated troughs or basins developed in the Wasatch Hinterland and western Wyo­ ming, and were subsequently filled with coarse elastics. These troughs were cutoff on the south by the Uinta Mountains which began rising in the east about the same time the troughs were developing. Thin layers of Laramide sediments were deposited from the northwest over the western end of the present Uinta

Mountains, as attested by the Evanston, Wasatch and Currant Creek

Formations that were later warped as the western end rose.

Eardley (1959) named the phases of the Laramide Orogeny, but did not recognize some important unconformities and only partly related the orogenic phases to the stratigraphy as it is now understood. The next section will relate the Laramide phases to the present stratigraphy.

The closing phases of the Laramide Orogeny brought con­

siderable igneous activity. In the Hinterland, the extrusive vol-

canics are from oldest to youngest: the City Creek Canyon volcan-

ics, the Fowkes Formation and the Norwood Tuff. In adjacent

areas igneous activity was more intense during the late Eocene AGE OROGENY NAME EVIDENCE RESULTANT VOLCANISM AND LOCATION FAULTS FORMATION WASATCH FAULT PERRYS HOLLOW BASIN AND RANGE FANGLOMERATE? CASCADLAN OROGENY KEETLEY VOLCANICS MIOCEN E YOUNGE R COTTONWOOD STOCK ETC. SEE TABLE 3 NORWOOD TUFF 1. BROAD N-E FOLDS IN LATE LARAMIDE NORWOOD, WASATCH AND OLDER OROGENY SEDIMENTS 2. UNCONFORMITY ABOVE NORTH & SOUTH UINTA MOUNTAIN WASATCH FORMATION FLANK FAULTS FOWKES FORMATION UPLIFT 3. UINTA MOUNTAINS GREEN RIVER FM. WASATCH FORMATION MID LARAMIDE OROGENY I. UNCONFORMITY BETWEEN ? CITY CREEK CANYON (more sevier to the west WASATCH FORMATION AND VOL. becoming weak near EVANSTON FORMATION Echo Canyon)

1. FOLDING N-E TRENDS 2. EC?-IO CANYON MISSING IN UPPER EVANSTON LOST CREEK AREA & EVANSTON UNCONF. ON OLDER ROCKS 3. ECHO CANYON CONGL. FOLDED NORTH HORN INITIAL MOVEMENT IN AND ERODED PRIOR TO DEPOSI­ EASTERN UINTA TION OF EVANSTON FM. IN ECHO MOUNTAIN AREA CANYON CURRANT CREEK 4. EVANSTON OVERLYING PALAE­ MOUNT RAYMOND . THRUST? LATE PHASE EARLY OZOICS ON S. L. C. SALIENT BASAL EVANSTON LARAMIDE OROGENY 5. BASAL EVANSTON CONGLO­ OVER AREA OF STUDY MERATE

1. NE TRENDING FOLDS IN ECHO CANYON EARLY LARAMIDE HINTERLAND? WILLARD THRUST? CONGLOMERATE OROGENY 2. LACK OF SEDIMENTS OF ABSAROKA THRUST? {probably extensive west MONTANA AGE TO THE WEST CHARLESTON THRUST? PRICE RIVER FM. of Wasatch fault line but 3. UNCONF. BELOW- THE PRICE NEBO THRUST?

LAT E CRETACEOU S PALEOCEN EOCEN OL1GOCEN reached into Hinterland) RIVER FM. & BENNION CREEK FM. CO o

Table 2. Orogenic phases and results in the Wasatch Hinterland 81 and Oligocene. Table 3 chronologically organizes the radiometric dates for several igneous bodies in the Hinterland and adjacent areas-

Following the Laramide Orogeny, the Wasatch Hinterland was cut by numerous basin and range type faults (Eardley, 1959) as the Cascadian Orogeny developed, but as before, the majority of the activity occurred west of the Wasatch Mountains.

PHASES OF THE LARAMIDE OROGENY

Early Laramide Orogeny - Late Cretaceous

Eardley (1 951, 1959) stated that the Echo Canyon Conglo­

merate resulted from an early phase of the Laramide Orogeny.

The Coalville-Echo Canyon area during the Late Cretaceous must

have been a subsiding basin to allow the accumulation of the 3100

feet of Echo Canyon Conglomerate. In the Coalville area, the

Echo Canyon Conglomerate lies conformably over Late Creta­

ceous strata, indicating that the Orogeny was not yet active in

folding the rocks in the eastern Hinterland. In the western Hinter­

land, however, broad folding may have begun during the Late

Cretaceous. Generally, the Echo Canyon Conglomerate is missing

in the western Hinterland.

The general consensus is that the Late Cretaceous saw

extensive thrust faulting (Crittenden, 1972; Armstrong , 1968; 82

K/Ar UNIT OR w Date 2 FORMATION LOCATION AUTHOR/YEAR W o 24*6 Little Cottonwood stock Crittenden; Kistler, 1966 o 25. 5 Little Cottonwood stock Crittenden; Kistler, 1966 5 25.8 Little Cottonwood stock Crittenden; Kistler, 1966 26 raf 28. 1 Little Cottonwood stock Crittenden; Kistler, 1966 30. 7*. 9 Hornblende latite tuff South Mountain Moore, 1973 31.0 Alta stock Cirttenden; Kistler, 1966 31.1 Little Cottonwood stock Crittenden; Kistler, 1966 31.2*. 9 Tickville rhyolitc flow Tickville Gulch Moore, 1973 31.6±.9 Eagle Hill rhyolite plug Mercur District Moore, 1973 32. 5 Alta' stock Crittenden; Kistler, 1966 32. 5 Alta stock Crittenden; Kistler, 1966 32. 5 Alta stock Crittenden; Kistler, 1966 33. 0 Keetley volcanics Crittenden; Kistler, 1966 33*1.0 Shaggy Peak plug Dry Canyon area Moore, 1973 33.7 Alta stock Crittenden; Kistler, 1966 34 Keetley volcanics Crittenden KiKisjtler, 1966 34. 7 Alta stock Crittenden & Kistler,, 1966 3 5 Keetley volcanics Crittenden & Kistler,, 1966 *36. 0 Norwood Tuff Norwood Canyon Evernden et al, 1964 36.5*1.1 Latite porphyry dike Pass Canyon area Moore, 1973 36. 7 Clayton Peak stock Crittenden & Kistler,, 1966 36.9+1.0 Quartz latite porphyry dike Bingham district Moore, 1973 37. 0 Pine Creek stock Crittenden & Kistler, 1966 37. 0 Traverse Range volcanics Crittenden & Kistler, 1966 37.1±1.1 Quartz latite prophyry dike Middle Canyon area Moore, 197 3 *37. 4 Norwood Tuff Norwood Canyon Evernden ct al, 1964 *37. 5 Norwood Tuff Norwood Canyon Evernden et al, 1964 37.6*.07 Bingham stock Bingham district Moore, 1973 38.Otl. 1 Monzonite porphyry stock Stockton district Moore, 1973 *38.3*1.5 Norwood Tuff East Canyon Reservoir This Report 38.6*. 18 Last Chance stock Bingham district Moore, 1973 38.6+1. 1 Quartz monzonite porphyry Selkirk Canyon Moore, 1973 38.8*.9 Andesite porphyry flow Bingham district Moore, 1973 "38 my" "47.7*1.5 Fowkes Formation Fossil Basin Oriel &c Tracy, 1970 50.9*2.0 City Creek Canyon volcanics S. L. C. Salient This Report 55.7*2.6 City Creek Canyon volcanics S. L. C. Salient This Report

Table 3. Radiometric dates for the late Laramide igneous deposits in the Wasatch Hinterland and adjoining areas. 83

Hammond and Parry, 1972; Sadeghi, 1972). The Willard, Charl­ eston and Nebo systems thrust younger rocks eastward along the western borders of the area, while the Absaroka Thrust was forming(? ) to the east. Debris from the allochthons of the western border thrusts, along with material from the deformed sediments of the authochton, was transported eastward and deposited as the

Echo Canyon Conglomerate, Price River and Bennion Creek

Formations- The early Laramide orogenic movements were probably most dramatic west of the present Wasatch line, in the

older Sevier Orogenic belt, but the unconformity below the Price

River Formation indicates that they reached the western Uinta

Basin and probably did likewise in the western Hinterland.

Late Phase of the Early Laramide Orogeny - Late Cretaceous

Eardley (1959) named the late phase of the early Laramide

Orogeny, but was unaware of the resulting unconformities and

sediments. The northeast-southwest folds that probably were

initiated in the early Laramide Orogeny were accentuated near

the end of the Cretaceous, as attested by the Mesozoic and Pale­

ozoic rocks unconformably underlying the Evanston Formation

in the Salt Lake City Salient and Lost Creek areas- During the

same phase, folding extended eastward into the basin filled by

the Echo Canyon Conglomerate (see Figure 33), creating the 84

Figure 33. Unconformity between the underlying Echo Canyon Conglomerate and the Evanston Formation in lower Echo Canyon. 85 unconformity between the Evanston Formation and Echo Canyon

Conglome rate-

During this phase of the early Laramide Orogeny, the Echo

Canyon Conglomerate was locally removed and re- deposited as part of the basal Evanston Formation- Portions of the Uinta

Mountains may also have supplied coarse debris for the basal conglomerate of the Evanston Formation- The upper, finer- grained rocks of the Evanston Formation were deposited in an environment where swamps and bogs were common- The source

rocks for the upper beds are uncertain and need petrographic

study, but they appear to be the Precambrian beds of the western

allochthons- Climatic changes and/or an uplift to the west pro­

bably caused the deposition of the upper Evanston Formation-

Local thrusting and faulting probably occurred during the

late phase of the Laramide Orogeny. The Mount Raymond Thrust

(Crittenden, personal communication) may have formed at this

time and continued movement on t he western border thrusts can­

not be ruled out.

Mid - Laramide Orogeny - Late Paleocene to Early Eocene

For the first time volcanics appear during the mid-Laramide

Orogeny. The City Creek Canyon volcanics lie unconformably (?)

upon the Evanston Formation and unconformably below the Was- 86

atch Formation. Elsewhere in the Hinterland after deposition of

the Evanston Formation a renewed surge of tectonic activity

deformed the older rocks and initiated the floods of coarse clastic

sediments which formed the Wasatch Formation. Throughout

the Hinterland, the Wasatch Formation is found to unconformably

overlie Precambrian, Paleozoic and Mesozoic rocks that were

uncovered as a result of the renewed tectonic activity, or that

were never completely covered (? ) by the Evanston Formation

(see figures 34, 35 and 36). At some localities, probably the

centers of the depositional basins, continuous deposition is pre­

sumed through Evanston and Wasatch times. At these locations,

'i. e. , East Canyon, Morgan Valley, and Lost Creek, no uncon­

formities are present between the two formations.

Late Laramide Orogeny - Late Eocene to Early Oligocene

Besides the considerable volcanics, the late Laramide

Orogeny saw the western Uinta Mountain uplift which gently

folded the Wasatch Formation along the north flank of the Uintas

in Chalk Creek. To the north during the late Eocene, the Wasatch

Formation and all older formations were slightly folded before

the deposition of the Norwood Tuff. In the Hinterland, the Wasatch

Formation and Norwood Tuff have been cast into broad folds sev­

eral miles across. This type of folding is believed to be charac-

0 87

Figure 35. Unconformity between the folded Paleozoic beds and the Wasatch Formation. 88

Figure 36. Unconformity between the Evanston Formation and the Wasatch Formation in Heiners Creek. teristic of the Laramide Orogeny, although Eardley (1959) be­ lieved it to represent the beginnings of the Cascadian Orogeny.

The most characteristic event of the Late Laramide Orogeny is the extensive volcanic activity. ECONOMIC AND ENGINEERING GEOLOGY

To date the Late Cretaceous and early Tertiary formations of the Wasatch Hinterland have yielded little of economic value.

The Lost Creek Coal Field was mined in the early 1900's and produced coal for the residents of the area. The seams

(up to 6 feet thick) of subbituminous B coal (Doelling, 1972) were mined from the Evanston Formation. Seams are known in the tributary canyons of Lost Creek, but have produced little. The

Evanston Formation in Utah has yielded no other coal outside of the

Lost Creek Field. The Wasatch Formation of Dagget County is reported to contain thin shaley lenses of coal (Doelling, 1972).

The Wasatch, Evanston and Echo Canyon Formations were studied by Mullens (1971) for heavy minerals. The few flakes of gold recovered in the study led Mullens to conclude that there are no placer gold deposits in these formations.

No oil or gas has been discovered to date in any of the Late

Cretaceous or early Tertiary deposits of the Hinterland of north­ eastern Utah. Throughout the Hinterland these formations are at or near the surface and show no signs of residual oils. West of the Wasatch Fault in the Great Salt Lake Basin the Evanston and

Wasatch Formations can be expected at depths up to 10 or 12 thousand feet. Oil or gas may be trapped in these sediments at 91 depth. Folding during the middle and late Laramide Orogeny may have significantly warped the beds causing structural traps for oil and gas. If significant structural or strati graphic traps have formed,the impermiable clays of the City Creek Canyon volcanics may form a significant cap rock for the trapping of oil and gas.

LANDSLIDING

Where the Wasatch Formation is cut into steep slopes by

erosion or construction landsliding may occur (see Figure 37).

The poorly consolidated lenses of mudstone or shale may not

support the heavy beds of conglomerate and sandstone causing

slumping. Figure 37. Landslide in the elastics in Echo Canyon. Landslides are common in the poorly cemented conglomerates, siltstones and sandstones. CONCLUSIONS

The Echo Canyon Conglomerate, Evanston Formation and

Wasatch Formation are molasse-type sediments, which along with the volcanic Fowkes Formation and Norwood Tuff were deposited in the Wasatch Hinterland during the Laramide

Orogeny, and were deformed at different times and places by the same orogeny.

The Echo Canyon Conglomerate was deposited in the center of the Wasatch Hinterland from west to east during the Early

Phase of the Laramide Orogeny (Late Cretaceous).

The'Echo Canyon Conglomerate is tentatively correlated with the

Price River and Bennion Creek Formations of the western

Uinta Basin. Lithologic similarities, fossil assemblages, paleo-

environment and similar orogenic phases are the bases for this

correlation.

The Late Phase of the Early Laramide Orogeny deformed the

rocks of the Wasatch Hinterland and resulted in the deposition

of the Evanston Formation.

The Evanston terminology is extended westward to include the

conglomerate and associated beds in the Salt Lake City Salient.

Further, the Evanston Formation is correlated with the North 94

Horn Formation of the western Uinta Basin.

6- The Evanston Formation on the Salt Lake City Salient is over­

lain by approximately 900 feet of tuffaceous clays and volcanic

breccias tentatively named the City Creek Canyon volcanics.

7- K/Ar radiometric dating of two samples of the volcanic breccias

gave dates of 50. 9+ 2. 6 and 55. 7+ 2. 0 m. y. , interpreted as

early Eocene.

8- The Middle Phase of the Laramide Orogeny locally deformed

the sediments of the Wasatch Hinterland and produced the

conditions necessary for the deposition of the Wasatch Formation.

9- Two facies of the Wasatch Formation are recognized in the

Wasatch Hinterland: the western conglomerate facies and the

eastern sandstone-nrudstone facies.

10-Imbrication in the Wasatch Formation indicates a western source

area for the formation except on the Salt Lake City Salient

where the paleocurrent was from east to west.

11- The Wasatch Formation of the Salt Lake City Salient is restricted

to early to middle(? ) Eocene (Wasatchian) in age. Elsewhere

in the Hinterland the Wasatch may extend into the Paleocene.

12-During the Late Phase of the Laramide Orogeny all the sediments

of the Hinterland including the volcanic Fowkes Formation and

Norwood Tuff were deformed.

13-A K/Ar radiometric age date of 38. 3+1.5 m. y. of the volcanics

near East Canyon Reservoir corresponds closely with prior age dates for the Norwood Tuff.

14-Precambrian and Paleozoic rocks beneath the Great Salt Lake

Valley may possibly be overlain by 1100+ feet of the Evanston

Formation, 900+ feet of the City Creek Canyon volcanics and

2000+ feet of the Wasatch Formation.

1 5-A formation previously mapped as part of the Wasatch (Knight)

Formation is tentatively named the Perrys Hollow fanglomerate

of probable Pliocene or Miocene age. The fanglomerate is

cut by faults believed to be part of the Wasatch Fault system;

it doubtless extends under the Salt Lake Valley.

16-Distinct time breaks between the Laramide and Sevier Orogenies

and the Laramide and the Cascadian Orogenies probably do not

exist; the transition appears to be gradual in both cases. i

However, compressive folding of the Norwood Tuff suggests

that Laramide-type folding extended into the Oligocene.

17-The westward dipping foliation in the Precambrian Farmington

Canyon Complex contrasted by the eastward dip of the overlying

Wasatch Formation and Norwood Tuff in west Morgan Valley

suggests that the Wasatch Mountains have been tilted eastward

at least 45 degrees since the deposition of the Norwood Tuff. BIBLIOGRAPHY

Armstrong, Richard Lee, 1968, Sevier Orogenic Belt in Nevada and Utah: GSA Bull. , Vol. 79, No. 4, p. 429-458.

Barret, David W. , 1953, Micropaleontology of the Evanston Forma­ tion, Southwestern Wyoming: M. S. Thesis University of Utah.

Bell, G. L. , 1952, Geology of the Northern Farmington Mountains, in Geology of the Central Wasatch Mountains, Utah: Utah Geological Society Guidebook to the Geology of Utah, No. 8, p. 38-51.

Bromfield, Calvin S. , 1968, General Geology of the Park City Region, Utah: Guidebook to the Geology of Utah, No. 22, p. 10-29-

Burger, John A. , 1955, Geology of Central Uinta County, Wyoming: M. S. Thesis, University of Utah.

, 1963, The Cretaceous Systems of Utah: Surface, Structure and Stratigraphy of Utah, Utah Geol. and Mineral Survey Bull. 54A.

Coody, Gilbert L. , 1957, Geology of the Durst Mountain Huntsville Area, Morgan and Weber Counties, Utah: M. S. Thesis, University of Utah.

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MEASURED SECTION

The section was measured north of t\\e road leading from

East Canyon Reservoir to Morgan Valley. The section begins in

SW-1/4 of section 31, T. 3N. , R. 3E. , Morgan County.

Quaternary

Alluvium and stream gravels. Erosional Surface.

Tertiary

Wasatch Formation

Unit Feet

1. Covered, red to brown soil, occasional pebbles, cobbles and bouHers(up to 1 ft. in diameter) • • 400

2. Interbedded conglomerate, siltstone, and sand­ stone. Conglomerate is framework-type, red to orange, generally debris covered with pebble to boulder size clasts (up to 2 ft. in diameter). Clasts are approximately 80% quartzite, 10% limestone (Paleozoic), occasional Wasatch rip-ups of rounded pebbles of oncolitic lime­ stone. Matrix is sandstone, red or orange, silty, fine to coarse grained, poorly sorted with calcareous cement. Bedding is massive (10 ft. ). Sandstone and siltstone are red to reddish purple, in thin lenses 205

3. Limestone, yellow-gray, weathers gray, onco­ litic, coarse grained, silty, abundant oncolites (up to 1 ft. in diameter), occasional pebbles, massive bedding (5 ft.'), very well cemented, Wasatch Formation-- Continued 104

Unit Feet

resistant ridge former 5

4. Covered, soil is red; Pebbles and cobbles of quartzite and sandstone 91

5. Sandstone, white, silty, very fine to coarse grained, angular to subangular, very thick bedding (4 ft. ), well cemented, calcareous cement . . . . 4

6. Conglomerate, framework, white or red, weathers red. Clasts are pebble to boulder size (up to 1 ft. ), well rounded. Matrix of sandstone, white, friable, poorly sorted. Forms small lenses (1-3 in.), A channel deposits, massive bedding, calcareous cement, poorly cemented 15

7. Interbedded sandstone and siltstone. Sandstone, red, silty, fine to medium grained, good sorting, calcareous cement. Siltstone, limey, thick bedding (3-5 ft. ) 10

8. Covered, soil is red, no pebbles or cobbles ... 311

9« Sandstone, red, silty; fine to coarse grained, subrounded to subangular, poorly sorted, massive bedding, calcareous cement 48

10. Conglomerate, framework, red. Clasts are pebble to boulder size (up to 2 ft. ) of yellow, white, pink, orange, and gray quartzite, chert and limestone. Matrix of sandstone, red, silty, fine to coarse grained, subangular to subrounded, poorly sorted. Massive bedding (greater than 10 ft. ), good cementation 52

11. Covered, soil is red to brown with pebbles, cobbles, and boulders (up to 3 ft. ) of quartzite, sandstone, and limestone 1

12. Covered, soil is brown, sandy, no pebbles, cobbles or boulders, decrease in vegetation 33 105 Wasatch Formation-- Continued

Unit Feet

13. Covered, soil is red to brown with abundant clasts, pebble to boulder size (up to 3 ft.) of quartzite, sandstone and limestone, well rounded . . 238

14. Interbedded conglomerate and sandstone. Conglom­ erate contains pebble, cobble and boulder clasts (up to 1 1/2 ft. ), of 85% quartzite, 10% limestone. Sandstone, red, coarse to fine grained, subangular to subrounded, poorly sorted 50

15. Covered, soil is red to brown with pebbles, cobbles and boulders (up to 2 ft. ), remnant boulders of weathered sandstone typical of the Wasatch .... 110

16. Interbedded conglomerate and sandstone. Conglo­ merate is red with clasts, pebble, cobble and boulder size (up to 2 ft. ), well rounded, mostly quartzite. Matrix is red, fine to coarse grained, poorly sorted, subangular to subrounded, thick bedded, cut and fill stream channels 67

17. Covered, soil is red to brown, abundant quartzite, sandstone and limestone, pebbles and cobbles in lower half of the unit 130

18. Interbedded claystone, sandstone and siltstone. Sandstone, red, very fine to medium grained, subangular to subrounded, very limey in places, cross-stratified, medium to thick bedded (up to 1 1/2 ft. ). Siltstone red to yellowish-green or reddish- purple. Claystones, red and yellowish-green, thin bedded, very calcareous 10

19- Conglomerate, white, pink or light green, pebble, cobble and boulder size clasts (up to 1 ft. ), frame­ work. Clasts, well rounded of quartzite, sand­ stone, limestone, chert, well imbricated, thick bedded, very calcareous, good to poor cementation 5

20. Interbedded sandstone, siltstone and claystone. Sandstone, red to reddish-green, silty, very fine to coarse grained, angular to subrounded, thin to thick bedded, very calcareous, poor to good cementation. Siltstone, red to reddish- 106 Wasatch Formation-- Continued

Unit Feet

green, sandy. Claystone, red to reddish-green, silty, beds are often wedge shaped lenses .... 69

21. Conglomerate, red, weathers to a yellowish-green. Clasts are pebble, cobble and boulder size (up to 2 ft. ), framework, well imbricated, last 2 ft. of unit contains pebbles and cobbles smaller than 6 in. Clasts are mostly quartzite, with some Paleozoic(? ) limestone and various sandstones, well rounded. Matrix is sandstone, red, very fine to very coarse grained, subangular to subrounded, massive bedding (5 ft. ), calcareous cement, poor to fair cementa­ tion 5

22. Interbedded sandstone and siltstone. Sandstone, red, weathers yellowish-green in blotches, very limey with some oncolites, medium to fine grained, silty, thick bedded (up to 2 ft.'), poorly cemented. Siltstone, red, weathers yellowish-green or reddish- purple, limey, sandy, poorly cemented, thick bedded 48

23. Interbedded claystone, sandstone and siltstone. Sandstone, red, very fine to medium grained, subangular to subrounded, very limey in places, cross-stratified, thick bedded (up to 11/2 ft.). Siltstone, red to yellowish-green or reddish-purple. Claystone, red and yellowish-green, thick bedded, very calcareous 24

24. Limestone, oncolitic, red to yellowish-green, coarse grained, sandy and silty, abundant oncol­ ites, resistant 3

2 5. Interbedded claystone, sandstone and siltstone. Sandstone, red very fine to medium grained, subangular to subrounded, very limey, cross- stratified, thin to thick bedded (up to 1 1/2 ft. ). Siltstones, red to yellowish-green or reddish purple. Claystone, red and yellowish-green, thick bedded, very calcareous 24 107 Wasatch Formation-- Continued

Unit Feet

26. Covered, soil is red to brown, numerous quartzite pebbles, boulders and cobbles (up to 1 ft. ), well rounded or angular, some Paleozoic limestone clasts . . 382

27. Sandstone, red, occasional thin yellow bed, fine to coarse grained, good sorting, subangular to subrounded, thick to massive bedding (1-8 ft. ); calcareous cement; good cementation; cross- stratification present in some beds 53

28. Interbedded conglomerate and sandstone. Conglo­ merate, framework, pebble to boulder size clasts (up to 2 ft. ) of approximately 85% quartzite cobbles, pebbles and cobbles, with some sandstone and chert. Matrix, sandstone, white to red, silty, poorly sorted, very fine to very coarse grained, angular to subrounded. Massive bedding (5 ft. ), calcareous cement, resistant, well cemented. Sandstone, red, silty, poorly sorted, fine to coarse grained, subangular to well rounded, thin to medium bedded (1 in. to 1 ft.), cross-stratified, calcareous cement 11

29« Interbedded sandstone and siltstone. Sandstone, red silty, thick to medium bedded, calcareous cement, poor to fair cementation, some beds are cross- stratified, worm tracks. Siltstone, weathers red, yellowish-green, and purple, some beds are very limey and weather to a marly texture, medium bedded, poor to fair cementation 152

30. Covered, red, sandy soil, very few pebbles, no cobbles or boulders 17

31. Sandstone, red, coarse to medium grained, angular to subrounded, calcareous cement, fair to poor cementation, thin to moderate bedding, large scale cross-stratification 17

32. Conglomerate, red, framework, pebble size, well sorted, clasts mostly quartzite, 5-10% Paleozoic •(? ) limestone. Massive bedding (15 feet thick); moder­ ately cemented, calcareous cement. Matrix is 108 Wasatch Formation- - Continued

Unit Feet

sandstone red, silty, very fine to coarse grained, subangular to subrounded 15

33. Covered, red soil, debris is typical Wasatch sandstone 33

34. Interbedded sandstone and conglomerate. Conglo­ merate, red, approximately 10% of the total unit, framework, pebble size, well rounded clasts of quartzite, sandstone, limestone and chert. Sand­ stone, red, silty, very fine to coarse grained, subangular to angular, calcareous cement, fair cementation, large scale cross-stratification in cut and fill channels Z0

35. Interbedded conglomerate and sandstone, red to gray in color* Conglomerate, pebble to boulder size (up to 1 1/2 ft. ), clasts of quartzite, sandstone, limestone and chert, massive bedding (greater than 10 ft. ), calcareous cement, moderate cemen­ tation, framework. Matrix is sandstone, silty, fine to coarse grained angular to subangular. Sandstone , red comprises approximately 20% of the unit, fine to coarse grained, large scale festoon cross- stratification in cut and fill channels 33

36. Interbedded sandstone and siltstone, red. Sand­ stone, silty fine to coarse grained, angular to subrounded, calcareous cement, moderate to good cementation, cross-stratified. Siltstone, sandy, well cemented, massive bedding 37

37. Interbedded conglomerate and sandstone; red, massive bedding (greater than 10 ft. ). Conglomerate, red, pebbles and cobbles, well rounded, moderate sorting of pebbles and cobbles, clasts, quartzite, sandstone, chert, limestone, well cemented, framework. Sandstone, red, medium to coarse grained, calcareous cement, well cemented, poorly sorted, lense shaped beds, large scale festoon cross-stratification 47 109 Wasatch Formation-- Continued

Unit Feet

38. Interbedded sandstone and siltstone; weathers red, gray or yellow-green. Sandstone, silty moderately sorted, very fine to coarse grained, subangular, calcareous cement, poor to well cemented, thick to massive bedding a yellow-green sandstone bed is cross-stratified with poorly developed ripple marks. Siltstone, red, gray, or yellow-green, sandy, calcareous cement 49

39' Interbedded conglomerate and sandstone. Conglo­ merate, red, framework, poorly cemented, pebbles, boulders and cobbles (up to 1 ft. ), 90% pebbles, quartzite clasts are white, red, gray, orange, yellow, and purple; sandstone are red, yellow, tan: limestone are blue-gray,• white and gray. Matrix, red, fine to coarse grained, poorly sorted, subangular, calcareous cement. Sandstone, red, silty, medium to coarse grained, well cemented, calcareous, thick to massive bedding (3-10 ft. ) . . 59

40. Interbedded sandstone and stilstone: Sandstone, red, silty, coarse to fine grained, angular, thin to thick bedded (up to 3 ft. )• Siltstone, sandy, red, calcareous cement 11

41. Interbedded conglomerate and sandstone. Conglo­ merate, red, poorly cemented, pebbles and cobbles (up to 9 in. in diameter), approximately 80% pebbles, well rounded, quartzite cobbles and pebbles yellow, red purple, approximately 10% blue-gray Paleozoic limestone, all clasts are stained red. Matrix is sandstone, red friable, fine to coarse grained, angular, some quartz grains show crystal faces. Sandstone, silty, red beds Z to 3 in. lense of siltstone separating beds of sandstone above and conglomerate below .... 60

4Z. Interbedded conglomerate and sandstone. Sand­ stone, red coarse to medium grained, subangular to rounded. Conglomerate, yellow to gray in color, pebbles and cobbles, well rounded. Cobbles of quartzite, white, red gray, orange and yellow. Pebbles generally of quartzite, sandstone, and limestone in decreasing abundance. Matrix is 110 Wasatch Formation- - Continued

Unit Feet

sandy siltstone, poorly sorted, yellow, fine to coarse grained, subangular to subrounded, calcar­ eous cement . . 35

43. Sandstone, red, fine to medium grained, subangular to subrounded, thin to thick bedded (up to 3 ft. ), contains worm holes filled in with siltstone, cross- stratified, occasional siltstone rip-up, orange in color 45

44. Interbedded sandstone and conglomerate, lenticular, bedding up to 10 ft. thick. Sandstone, red fine to coarse grained, subangular, calcareous cement; lenses appear to be cut and fill channel deposits. Conglomerate, mostly pebble size with occasional cobbles of quartzite 40

45. Sandstone, silty, red, fine grained, subangular, thin to thick bedded (up to 3 ft. ), calcareous cement 18

46. Conglomerate, framework, red; contains up to 1 ft. sandstone lenses. Cobble size quartzite clasts, white, red gray, orange and yellow; sandstone clasts, red and yellow; limestone clasts (Paleozoic) gray-blue. Matrix is silty sandstone, red, coarse grained, subangular, poorly sorted, calcite cement, massive bedding 50

47. Interbedded sandstone and siltstone. Sandstone, silty, red to yellowish-orange, medium to fine grained, medium to thick bedded, large scale festoon cross-stratification; sandstones contain limey intraformation rip-ups which weather orange-gray. Siltstones, sandy, red, calcareous cementation. Fractures within the sandstones and siltstones are filled with calcite 49

48. Conglomerate, red to gray-red, framework, massively bedded (10 plus ft. ), pebble to boulder size (up to 16 in. in diameter), individual clasts, well rounded, predominantly quartzite with sand­ stone, limestone and chert clasts. One small 3 in. sandstone lense 28 111 Wasatch Formation-- Continued

Unit Feet

49* Interbedded sandstone and conglomerate. Sandstone, red, coarse to fine grained, poorly sorted, massive bedded (10 plus ft. ) thick, large scale festoon cross- stratification, some beds contain apparent worm tracks and appear organically reworked; occasional conglomerate lenses (up to 4 ft. ) thick, pebble to cobble size, clasts of quartzite, sandstone and limestone, some lenses are 90% white quartzite . • 80

50. Interbedded siltstone and sandstone. Grades from sandstone at bottom to siltstone at the top. Sand­ stone, red, coarse grained, subangular, occasional pebble, siltstone, red, marlstone texture, erosional surface (stream channel) at the base of the unit, lenticular beds, massive bedding (10 plus ft. thick) . 24

51. Conglomerate, framework, cobble size quartzite clasts, ' white, red, gray, orange and yellow; while limestone (Paleozoic) is gray-blue. Matrix is silty sandstone, red, coarse grained, subangular, poorly sorted, calcite cement thick to massive bedding (3-10 ft. ) 38

52. Covered, red dirt, pebble to boulder well rounded clasts (up to 2 ft. ) .... 57

53. Siltstone, sandy, red, 'weathers to a marlstone texture, interbedded with minor silty sandstone lenses, medium grained and angular 3

54. Conglomerate, framework, pebble to cobble size, predominantly quartzite clasts with minor amounts of well rounded sandstone and limestone clasts. Matrix is sandstone, red, poorly sorted, fine to coarse grained, angular to subangular 3

55. Covered, cobble size quartzite, limestone, and red sandstone clasts on the surface 48

56. Sandstone, silty, orange to red, medium grained, subangular to subrounded, bedding up to 1 ft. thick, forms steep slope lacking in vegetation, may contain thin covered conglomerate lenses 31 112

Wasatch Formation-- Continued

Unit Feet

57. Covered, dirt, brown to red in color, pebble to boulder gravel with individual clasts of well rounded quartzite, limestone, and schist (up to 4 ft. in diameter). Oncolitic limestone fragments increase in the upper half of the unit 130

58. Covered, dirt, brown to red in color, pebble to boulder gravel with individual clasts of well rounded quartzite, limestone and schist (up to 4 ft. in diameter)- Oncolitic limestone fragments increase in the upper half of the unit. Quartzite boulders (up to 4 ft. ), limestone clasts pebble to cobble size; quartzite clasts, white, red, orange, yellow and purple 818 •

TOTAL THICKNESS 4468

Cretaceous - Tertiary (Upper Cretaceous to Paleocene)

Evanston Formation

Interbedded sandstone, siltstone grits, claystone and pebble conglomerate, gray to tan, abundant iron nodules and iron staining common in some beds, slope former • 500+ VITA

Name Daven Craig Mann

Birthplace Salt Lake City, Utah

High School Skyline High School Salt Lake City, Utah

University- University of Utah

Degree 1972 B. S. University of Utah

Profession Positions Curator Sample Library, Utah Geolog ical and Mineral Survey and Geologic aid.

Publications Catalog: Sample Library, Circular 55, May 1973, UGMS