Paleocene and 

Lower Eocene Units in 

< the Southern Part of the

 »

Piceance Creek Basin 

" ^ Colorado

" By JOHN R. DONNELL

CONTRIBUTIONS TO STRATIGRAPHY

»

< GEOLOGICAL SURVEY BULLETIN 1274-M
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HIGKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

U.S. GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 20 cents
CONTENTS

Page

Abstract ....................................................................................................................Ml

Introduction ...............^........................^..................................................................... 1

Previous terminology .............................................................................................. 2

Stratigraphic relations of the upper Paleocene and

lower Eocene rocks ...................................................................................... 6

Ohio Creek Formation .................................................................................... 6

Atwell Gulch Member (new) of the Wasatch Formation ........................ 6

Molina Member (new) of the Wasatch Formation ................................ 8

Shire Member (new) of the Wasatch Formation .................................... 12

Summary of new terms and ages ........................................................................ 13

Reference sections of the Atwell Gulch, Molina, and Shire

Members of the Wasatch Formation ........................................................ 13

References cited ........................................................................................................ 18

ILLUSTRATIONS

Page

FIGURE 1. Map of the Piceance Creek basin, northwestern Colorado ..........M3

2. Map of the area along Plateau Creek and along the

Colorado River between Rifle and DeBeque Canyon ................ 4

3. Generalized stratigraphic relations of the Wasatch and 

adjacent formations in the southern part of the 

Piceance Creek basin ...................................................................... 7

4. Molina Member of the Wasatch Formation, capping 

hill east of DeBeque, underlain by incompletely 

exposed Atwell Gulch Member ...................................................... 8

5. Steeply dipping rocks at Rifle Gap .................................................. 9

6. Vertebrate quarry in Atwell Gulch Member .................................. 10

TABLE

Page

TABLE 1. Cretaceous and Tertiary names used in geologic

reports on the Piceance Creek basin ............................................ M5

in

CONTRIBUTIONS TO STRATIGRAPHY

PALEOCENE AND LOWER EOCENE UNITS IN THE

SOUTHERN PART OF THE PICEANCE CREEK

BASIN, COLORADO

By JOHN R. DONNELL

ABSTRACT

The age relations of the Wasatch Formation in northwestern Colorado 

have long been controversial. It is the purpose of this paper to summarize 

available paleontological information on the Wasatch Formation, to describe 

the general stratigraphic relations, and to designate formal names for informal units initially described by Donnell in 1961.

Sedimentary rocks in the interval between the Ohio Creek Formation 

and the Green River Formation are assigned to the Wasatch Formation of 

Paleocene and Eocene age. In an area of several hundred square miles in 

the vicinity of DeBeque, Grand Valley, Mesa, and Collbran, Colo., the Wasatch 

may be separated into three members. The upper and lower members, herein 

named Shire and Atwell Gulch, are dominantly variegated claystones. The 

intervening Molina Member consists principally of thick brown ledge-forming 

massive sandstones with thin interbeds of variegated claystone. The lower 

200 feet of the Atwell Gulch Member contains Paleocene plant and vertebrate 

fossils. No fossils have been reported from the Molina or the upper part of 

the Atwell Gulch Member; however, the Shire Member contains middle early 

and late early Eocene vertebrate fossils. Stratigraphic equivalents of these 

three members crop out along the Grand Hogback between Rifle and Meeker, 

Colo.

INTRODUCTION

The Ohio Creek Formation, a Paleocene unit characterized by 

conglomeratic sandstones containing mostly pebbles of chert and 

quartzite derived primarily from Paleozoic sediments, marks the 

boundary between the Cretaceous and Tertiary Systems throughout most of the Piceance Creek basin. Immediately overlying the 

Ohio Creek Formation, at some places in the basin, is a series 

of drab brown and gray shales and sandstones with several thin 

nonpersistent interbeds of lignite and carbonaceous shale. These 

beds are herein named the Atwell Gulch Member. Elsewhere, this 

sequence of beds intertongues with varicolored claystones, siltMi
M2 CONTRIBUTIONS TO STRATIGRAPHY

stones, and sandstones, generally mapped as part of the Wasatch 

Formation. Late Paleocene vertebrate and plant remains have 

been found near the base of the unit near DeBeque and Molina 

and in the area between these places (figs. 1, 2).

Overlying this lowest sequence of beds in an area of several 

hundred square miles surrounding DeBeque is a unit herein named 

the Molina Member, consisting mainly of sandstone with thin 

interbeds of varicolored claystones and siltstones. A similar, but 

not as well defined, unit is at approximately the same stratigraphic horizon along the eastern margin of the Piceance Creek 

basin between the Colorado and White Rivers.

Varicolored claystones and siltstones, mainly purple, lavender, 

and red, and minor amounts of lenticular brown sandstone lie 

between the dominantly sandstone sequence and the basal unit of 

the Green River Formation, the Douglas Creek Member, in much 

of the Piceance Creek basin. This unit is herein named the Shire 

Member.

PREVIOUS TERMINOLOGY

Gale (1910, p. 81), although recognizing along the Grand Hogback a sequence of rocks of possible equivalence to the Fort Union 

Formation, stated, "As shown here and also as formerly mapped 

by the Hayden Survey, all the beds overlying the Coal-bearing or 

Mesaverde formation were included in the Wasatch up to the sandstones that form the basal portion of the next succeeding or Green 

River formation." (See table 1.)

Along the southern margin of the Piceance Creek basin (in 

the West Elk Mountains and on Grand Mesa) Lee (1912) regarded 

the Wasatch ("Ruby") Formation as the rock unit lying between 

the Ohio Creek Conglomerate and the Green River Formation.

In the Book Cliffs area north of Grand Junction, Erdmann 

(1934) regarded as belonging to the Wasatch Formation those 

sedimentary rocks above his Tertiary (?) sandstone (which he 

tentatively correlated with the Ohio Creek Conglomerate to the 

south) and below the Green River Formation.

Patterson (1933) initially described Paleocene mammals from 

what he termed the "lower levels of the Ruby formation" in the 

vicinity of the Grand (Colorado) River. Later, Patterson (1934, 

1936, 1939) described additional Paleocene collections from the 

lower 200 feet of what he initially termed "Ruby formation." 

Wood and others (1941) called the beds between the Hunter Canyon Formation (of the Mesaverde Group) and the Green River 

Formation, DeBeque Formation.

Donnell (1961a) mapped all beds between the Mesaverde Formation and the Green River Formation with the Wasatch Forma-
PICEANCE CREEK BASIN, COLORADO M3

109° 108°

40

RIO BLANCO 

"GARFIELD

Douglas Pass

:>

FIGURE 1. Piceance Creek basin, northwestern Colorado. Surface rocks are 

Tertiary in the unpatterned area and pre-Tertiary in the shaded area.
M4 CONTRIBUTIONS TO STRATIGRAPHY

108-15'

39°30' -

39°15

39°00

FIGURE 2. Area along Plateau Creek and along the Colorado River between 

Rifle and DeBeque Canyon. A, reference section for Atwell Gulch Member; 

Bl, B2, B3, reference sections, Molina Member; C, reference section, Shire 

Member.

tion, and in the report (1961a, p. 844-845) mentioned an unnamed 

unit of Paleocene age that is the approximate equivalent of the
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M6 CONTRIBUTIONS TO STRATIGRAPHY

upper part of the Plateau Valley Beds of Patterson. In another 

report (Donnell, 1961b) the Wasatch was divided into three members, equivalent.to the Atwell Gulch, Molina, and Shire Members, 

in the vicinity of DeBeque. These consisted of upper and lower 

dominantly varicolored claystone members separated by a thick 

ledge-forming sandstone member. The lower member is equated 

with that part of the Plateau Valley Beds which overlies the Ohio 

Creek Formation.

STRATIGRAPHIC RELATIONS OF THE UPPER PALEOCENE AND 

LOWER EOCENE ROCKS

OHIO CREEK FORMATION

The Ohio Creek Formation in the Piceance Creek basin consists chiefly of a single massive sandstone or a series of massive 

sandstones that generally weather white and form a conspicuous 

band just above the ledge-forming brown sandstones of the uppermost beds of the Mesaverde Formation and below the dominantly 

shale and claystone slopes of the overlying Wasatch Formation. 

(See fig. 3.) In a few places, however, the sandstone of the Ohio 

Creek is dark red. The sandstones in the Ohio Creek Formation 

contain a distinctive suite of pebbles consisting principally of red 

and black chert, red and white quartzite, and white quartz, with 

minor amounts of limestone and granitic rock. The pebbles are 

erratically distributed through the sandstone and vary from a 

few small pebbles less than 1 inch in diameter that are scattered 

through a thick massive sandstone, as at the mouth of DeBeque 

Canyon, to beds containing abundant pebbles and cobbles as much 

as several inches in diameter. Because of varying lithology from 

place to place, the Ohio Creek is frequently difficult to recognize 

on electric logs from wells drilled for oil and gas. The Ohio Creek 

is exposed along the southern and eastern margin of the Piceance 

Creek basin; it is locally exposed in the Douglas Creek drainage 

and has been recognized in samples from some wells in the northcentral part of the Piceance Creek basin.

ATWELL GULCH MEMBER (NEW) OF THE WASATCH FORMATION

The Atwell Gulch Member of the Wasatch Formation is named 

from exposures along Atwell Gulch, the type locality, a tributary 

of Plateau Creek west of the town of Molina (section A, fig. 2). 

The section measured at the Ni/2 sec. 26 and the SV2 sec- 23, 

T. 9 S., R. 97 W., is designated as a reference section. It is the 

lowermost member of the Wasatch Formation in this area. The 

member rests on the Ohio Creek Formation and underlies the 

basal dominantly sandstone unit of the middle member of the 

Wasatch Formation. It can definitely be traced on the surface 

and in the subsurface over an area of several hundred square
PICEANCE CREEK BASIN, COLORADO M7

Winter Flats Grand Valley Rifle Gap

Garden Gulch Member

Shire Member

Wasatch Formation

F*aleocene-Eoc&ne boundary^ n

EXPLANATION 

X

Fossil horizon

Mesaverde Formation

Undifferentiated 

lithology

10 MltES

FIGURE 3. Generalized stratigraphic relations of the Wasatch and adjacent 

formations in the southern part of the Piceance Creek basin. Contacts 

queried where uncertain.

miles in the general area of DeBeque, Grand Valley, Mesa, and 

Collbran. A similar unit, not as well defined, can be delineated 

along the Grand Hogback north and east of Rifle.

Lithologically the Atwell Gulch Member is the most variable 

part of the Wasatch Formation. In the vicinity of DeBeque Canyon it contains, in the lower part, a carbonaceous shale and lignite 

zone that is traceable over a 5-square-mile area. Northeast and 

east of DeBeque (fig. 4), where the lower part is not exposed, 

the upper part consists of gray claystone and siltstone approximately 200 feet thick overlain by 150 feet of lenticular brown 

sandstone, carbonaceous shale, and lignite beds. This is lithologically very similar to stratigraphically equivalent rocks along the 

Grand Hogback (fig. 5) . South of DeBeque the lowest one-quarter 

of the member contains minor amounts of variegated claystone 

and numerous gray sandstone and siltstone lenses, some of which 

contain a suite of pebbles similar to that in the Ohio Creek Formation. The remainder of the member consists mostly of variegated claystone, minor amounts of lenticular sandstone, and a few 

thin fresh-water limestone beds. The Atwell Gulch Member ranges 

in thickness from about 700 feet on the outcrop along Atwell 

Gulch to approximately 1,850 feet in the subsurface south of 

Grand Valley.
M8 CONTRIBUTIONS TO STRATIGRAPHY

FIGURE 4. Molina Member of the Wasatch Formation, capping hill east of 

DeBeque, underlain by incompletely exposed Atwell Gulch Member. Interval 

"a" contains dominantly brown shale, black carbonaceous shale, and thin 

lignite beds.

The Atwell Gulch Member is late Paleocene (Tiffanian provincial age) and possibly early Eocene in age. Paleocene mammalian 

fossils have been collected from several localities and several horizons in the lower 200 feet of the member in the area around and 

between DeBeque and Molina (Patterson, 1939; fig. 6). In addition, Roland W. Brown (Donnell, 1961a, p. 845) collected and 

identified Paleocene plant fossils from the carbonaceous zone near 

the base of the member at the east end of DeBeque Canyon. 

F. H. Knowlton (Gale, 1910, p. 79) identified Paleocene plants 

from a zone about 200 feet above the Ohio Creek Formation at 

Rifle Gap along the west side of the Grand Hogback, a few miles 

north and east of Rifle. No fossils have been reported from the 

beds in the interval between the top of the member and a horizon 

about 200 feet above the base of the member.

MOLINA MEMBER (NEW) OF THE WASATCH FORMATION

The Molina (middle) Member of the Wasatch Formation is 

named from good exposures on a prominent hill north of Plateau 

Creek about 1 mile west of Molina, the type locality. Three reference sections are designated Bl, B2, and B3 (fig. 2). The basal 

boundary, a fairly sharp contact, is at the base of the lowest persistent arkosic sandstone that overlies the Atwell Gulch Member. 

The upper contact, a little less distinct, is at the top of the persistent sandstone sequence. Almost everywhere the upper sandstones are lenticular, and the contact varies in its stratigraphic 

position from place to place.
PICEANCE CREEK BASIN, COLORADO M9

FIGURE 5. Steeply dipping rocks at Rifle Gap. Upper, rocks of the Ohio 

Creek Formation (to left of dashed contact) and beds equivalent to the 

lower part of the Atwell Gulch Member at Rifle Gap. "a" is at position of 

"a"' in lower photograph. Arrows indicate plant localities. Lower, rocks 

equivalent to the Molina Member, the upper part of the Atwell Gulch Member, and the lower part of the Shire Member on the south side of Rifle Gap.
M10 CONTRIBUTIONS TO STRATIGRAPHY

FIGURE 6. Vertebrate quarry in Atwell Gulch Member (approximately 2,800 

ft east of west line and 400 ft south of north line, sec. 26, T. 9 S., R. 97 W.). 

Site is about 200 ft above Ohio Creek Formation. Quarry in circle; man 

(arrow) for scale.
PICEANCE CREEK BASIN, COLORADO Mil

The Molina Member is exposed along 200 linear miles of outcrop in the vicinity of Mesa and DeBeque (fig. 4), and it underlies 

the western half of Grand and Battlement Mesa, an area of more 

than 350 square miles that extends as far eastward as Collbran 

and Grand Valley. At Rifle Gap (fig. 5, lower photograph), beds 

possibly equivalent to the Molina Member are about 400 feet thick 

and they lie about 700 feet above the base of the Wasatch Formation. North of here, intermittent exposures along the Grand Hogback indicate that the Molina equivalent is present, but it is not 

as easily recognized as at Rifle Gap.

A similar sandstone zone about 2,000 feet above the Ohio Creek 

Formation is exposed along Colorado State Highway 13 north of 

Rifle and is recognizable in some of the wells in the eastern part 

of the Piceance Creek basin. This zone is not directly traceable 

into the Molina west of Rifle, but it is possibly correlative.

Continuous thick-bedded brown arkosic ledge-forming sandstone characterizes the Molina Member. Locally, individual sandstone beds are red, green, or gray..Minor amounts of variegated 

claystone form partings between the sandstone beds. In the outcrop, the proportion of claystone to sandstone increases westward 

where on the southwest side of Chalk Mountain and on Winter 

Flats (fig. 1) the sandstone beds are replaced by claystone and 

siltstone. The Molina Member is prominent east of the DeBeque 

cutoff road that connects U.S. Highway 6 and Colorado State 

Highway 65, and along Colorado State Highway 330 in the vicinity of Molina. In this area the sandstone is thicker bedded and 

coarser grained than elsewhere, and in places it is conglomeratic. 

The pebbles in the conglomerate are as large as several inches in 

diameter and are similar in composition to those in the Ohio Creek 

Formation.

The Molina Member ranges in thickness from a wedge edge 

in the vicinity of Chalk Mountain and Winter Flats to slightly 

more than 500 feet in the Mickelson 1 well (T. 11 S., R. 94 W.) 

and in the McCurry well (T. 9 S., R. 94 W.) (fig. 2). A unit that 

is the possible equivalent attains a thickness of more than 600 feet 

in the Carter and Carter 1 E. C. Hunter well (T. 6 S., R. 94 W.) 

(fig. 2) ; in this well, the sandstone beds are thin and separated 

by thick units of siltstone and variegated claystone. The basal 

sandstone in all three wells, as elsewhere in the surface and subsurface, appears to be the most persistent unit in the member.

No fossils have been reported from the Molina Member; however, Bryan Patterson (oral comimm., 1965) reported Eocene 

vertebrates from the beds immediately overlying the member at 

the type locality.
M12 CONTRIBUTIONS TO STRATIGRAPHY

SHIRE MEMBER (NEW) OF THE WASATCH FORMATION

The Shire Member of the Wasatch is named for excellent exposures along the headwaters of Shire Gulch in the NEVi sec. 19, 

T. 9 S., R. 96 W., the type locality. The measured section at the 

SE^ sec. 13, T. 9 S., R. 97 W., and the Si/2 sec. 18, T. 9 S., R. 

96 W., is designated as the reference section C in figure 2. The 

Shire is the upper member of the Wasatch Formation. Its base 

is at the top of the uppermost persistent sandstone in the Molina 

Member, and the top is at the base of the lowermost sandstone 

bed in the Douglas Creek Member of the Green River Formation.

The principal rock type in the Shire Member is claystone. The 

dominant colors are pastel shades of lavender, purple, and red. 

Some thick lenticular sandstone beds are elsewhere equivalent to 

the upper beds of the Molina Member. Above these lower thick 

sandstone beds are a few thin (1 ft to several feet thick) lenticular 

gray sandstone and gray claystone beds. Along the south flank of 

Battlement Mesa the uppermost part of the member intertongues 

with the Douglas Creek Member of the Green River Formation. 

On the north flank of Grand Mesa and the south flank of Battlement Mesa east of Collbran the upper part of the Shire is characterized by resistant lenticular brown ledge-forming sandstone beds 

separated from one another and from the overlying Green River 

sedimentary rocks by red claystone. These sandstone beds form 

topographic benches. At places, such as Red Mountain, a prominent hill 2 miles southeast of Collbran (fig. 1), the red claystone 

of the Shire Member is equivalent to sandstone of the Douglas 

Creek Member. The Shire Member along the Grand Hogback also 

intertongues with the lower part of the Green River Formation. 

Two thin tongues of the Green River Formation are exposed over 

several square miles east of DeBeque on the lower slopes of Mount 

Logan. These tongues cap minor benches in the upper 400 feet of 

the Shire Member and consist mainly of resistant brown calcareous 

sandstone and subordinately of a light-brown flaky shale. Fragments of a brown ostracodal limestone less than 1 inch thick are 

scattered on the surface of the capping sandstone at many places.

The Shire Member underlies an area equal to that underlain 

by the Molina Member. The Shire is about 900 feet thick in the 

type locality, thins to about 600 feet in the subsurface underlying 

Grand Mesa, and thickens to more than 1,800 feet in the subsurface in wells south of Grand Valley on the north flank of 

Battlement Mesa. The probable stratigraphic equivalent of the 

Shire Member along the Grand Hogback attains an exposed thickness in excess of 4,000 feet.
PICEANCE CREEK BASIN, COLORADO M13

As mentioned above, early Eocene mammal remains have been 

found in the lower part of the Shire Member at the type locality 

of the Molina Member. Wood (1962) described collections of the 

middle early Eocene and late early Eocene rodents from localities 

near the upper part of the Shire Member north of the Colorado 

River and about midway between Rifle and Grand Valley (fig. 3).

SUMMARY OF NEW TERMS AND AGES

Atwell Gulch Member. The Atwell Gulch Member is the lower 

member of the Wasatch Formation. It consists mostly of purple, 

lavender, red, and gray claystone and minor amounts of gray and 

brown lenticular sandstone and siltstone near the base. Paleocene 

vertebrates and leaves have been collected from the basal 200 feet 

of the Atwell Gulch Member; no fossils have been reported from 

the rest of the member.

Molina Member. The Molina Member is the middle member 

of the Wasatch Formation. It consists primarily of massive brown, 

gray, red, or green persistent sandstone beds with minor amounts 

of variegated claystone. No fossils have been reported from this 

member, but its probable age is early Eocene.

Shire Member. The Shire Member is the upper member of 

the Wasatch Formation. It consists primarily of purple, lavender, 

and red claystones and minor amounts of gray claystone, but contains some poorly bedded lenticular brown sandstone near the 

base of the member. In places, the upper part of the Shire Member 

intertongues with and is equivalent to the Douglas Creek Member 

of the Green River Formation. Early Eocene mammals have been 

reported from the lower part of the member near Molina and 

middle early and late early Eocene rodents have been reported 

from the upper part of the member west of Rifle.

REFERENCE SECTIONS OF THE ATWELL GULCH, MOLINA, AND 

SHIRE MEMBERS OF THE WASATCH FORMATION

[No sections measured at type localities]

A. Atwell Gulch Member of the Wasatch Formation, Af% sec. 26 and SVz sec.

23, T. 9 S., R. 97 W.

Thickness

Wasatch Formation, Atwell Gulch Member: (ieet>

Claystone, green ........................................................................................ 24.2

Sandstone and claystone, olive green .................................................... 30.0

Sandstone, gray, medium-grained, massive, lenticular ...................... 6.0

Claystone, lavender, medium-gray ........................................................ 50.7

Sandstone, brown, limonitic .................................................................... 10.0

Claystone .................................................................................................... 40.6

Sandstone, brown, medium-grained, massive, lenticular .................. 12.0

Claystone, purple; some lavender .......................................................... 53.2

Sandstone, brown, massive, lenticular .................................................. 8.0
M14 CONTRIBUTIONS TO STRATIGRAPHY

A. Atwell Gulch Member of the Wasatch Formation, Nl/z sec. 26 and SVz sec.

23, T. 9 S., R. 97 W. Continued Thickness (feet)

Wasatch Formation, Atwell Gulch Member Continued

Claystone, lavender and purple; some tan at base ............................ 49.3

Sandstone, gray ........................................................................................ 11.5

Claystone, lavender; some gray and brown ........................................ 25.1

Sandstone, gray, medium-grained ........................................................ 11.4

Claystone; lavender at top and base, gray in middle ...................... 31.6

Sandstone, gray, fine-grained ................................................................ 3.0

Claystone; gray at top, purple and lavender at base ........................ 10.0

Sandstone, gray, very fine grained to fine-grained;

calcareous cement; lenticular ............................................................ 3.5

Claystone, gray, purple, lavender; partially covered ........................ 81.2

Sandstone, brown, fine-grained to medium-grained;

forms prominent ledge ........................................................................ 10.0

Mudstone, brown ...................................................................................... 2.2

Limestone, gray ........................................................................................ 1.0

Sandstone, tan, fine-grained to medium-grained ; quartz and

feldspar; well consolidated ................................................................ 4.2

Claystone, gray, with 2 ft of brown siltstone;

weathers to recess ................................................................................ 17.4

Covered; probably claystone .................................................................. 17.4

Sandstone, brown, coarse-grained; red quartz grains

and feldspar; forms prominent ledge ........;..................................... 18.9

Sandstone, brown, fine-grained, and gray claystone;

unit forms recess .................................................................................. 1.9

Covered slope; probably contains fine-grained brown

sandstone and gray mudstone or claystone .................................... 11.6

Total Atwell Gulch Member of Wasatch Formation ................545.9

Ohio Creek Formation (incomplete) :

Sandstone, brown, coarse-grained; quartz; poorly

consolidated; forms slope .................................................................... 6.0

Sandstone, light-tan, coarse-grained; quartz; contains

some quartz and chert pebbles .............................................. ... ... 11.6

Conglomerate; well-rounded chert and quartz pebbles as

large as 3.5 in. by 2.5 in. ; forms recess between

underlying and overlying sandstones ................................................ 3.0

Sandstone, white to gray to light-tan, coarse-grained to very

coarse grained, poorly cemented; weathers to a slope.................... 75+

Total Ohio Creek Formation measured ........................................ 95.6+

Bl. Molina Member of the Wasatch Formation, Ny2 sec. 24, T. 9 S., R. 97 W.

Wasatch Formation, Molina Member:

Sandstone, gray, fine-grained to medium-grained, massive ............ 8.2

Claystone, gray and lavender; forms slope ........................................ 23.0

Sandstone, gray, medium-grained, massive; quartz sand; 

6-ft interval covered 10 ft below the top ........................................ 29.0

Covered slope; probably underlain by poorly consolidated

sandstone ................................................................................................ 11«2

Sandstone, brown, medium-grained to coarse-grained; 

quartz sand; forms prominent ledge ................................................ 36.7
PICEANCE CREEK BASIN, COLORADO M15

Bl. Molina Member of the Wasatch Formation, 2V% sec. 24,

T. 9 S., R. 97 W. Continued Thickness

(feet)

Wasatch Formation, Molina Member Continued

Covered slope ............................................................................................ 9.6

Sandstone, gray, medium-grained, massive; forms

prominent ledge .................................................................................... 12.8

Covered slope; some claystone and green sand .................................. 10.7

Sandstone, gray, medium-grained, massive ........................................ 3.0

Sandstone, green ...................................................................................... 1.0

Sandstone, gray, coarse-grained, pure quartz, poorly cemented .... 6.6

Covered slope; probably contains green claystone and

green sandstone .................................................................................... 23.5

Sandstone, dark-gray to light-tan, fine-grained,

massive; recess at base ........................................................................ 12.4

Sandstone, gray, medium-grained, massive; base of

prominent ledge .................................................................................... 9.1

Claystone, lavender to gray .................................................................... 22.8

Sandstone, gray, medium-grained ........................................................ 22.0

Sandstone, olive-green ............................................................................ 2.0

Sandstone, gray, coarse-grained, massive; basal part

contains pebbles .................................................................................... 6.0

Covered; claystone in upper 6 ft .......................................................... 23.2

Sandstone, brown, medium-grained, massive, poorly cemented,

slightly calcareous; %-in. to %-in. quartz and chert pebbles

at base; capped with gray, fine-grained calcareous sandstone .... 23.2

Covered; some claystone ........................................................................ 5.4

Sandstone, gray, fine-grained to medium-grained,

massive, calcareous .............................................................................. 13.8

Sandstone, brown, medium-grained to coarse-grained, massive,

poorly cemented; some gray sandstone at top ................................ 16.6

Covered; forms slope ................................................................................ 7.6

Sandstone, gray, fine-grained, massive ................................................ 6.2

Claystone, lavender with some gray .................................................... 8.7

Sandstone, tan to brown, medium-grained, persistent,

well-cemented ........................................................................................ 35.8

Total Molina Member of Wasatch Formation..............................390.1

B2. Molina Member of the Wasatch Formation, SVz sec. 81, T. 9 S., R. 95 W., 

and Nyz sec. 6,T. 10 S., R. 95 W.

Wasatch Formation, Molina Member:

Sandstone, light-gray, medium-grained; forms ledge ...................... 17.4

Covered slope; probably underlain by siltstone or claystone .......... 20.3

Sandstone, light-gray, fine-grained to medium-grained,

poorly bedded ........................................................................................ 20.3

Siltstone, gray; forms recess under overlying sandstone ........:....... 3.4

Covered; probably siltstone or claystone............................................... 11.6

Sandstone, fine-grained, thin-bedded to medium-bedded .................. 7.7

Covered interval ........................................................................................ 31.9

Sandstone, gray, medium-grained, crudely crossbedded;

forms a very prominent ledge ............................................................ 23.2

Poorly exposed; scattered exposures of dark-green siltstone

and dark-gray claystone; forms bench ............................................ 11.6
Ml6 CONTRIBUTIONS TO STRATIGRAPHY

B2. Molina Member of the Wasatch Formation, SVz sec. 31, T. 9 S., R. 95 W., 

and Ny2 sec. 6,T. 10 S., R. 95 W. Continued Thickness

(feet)

Wasatch Formation, Molina Member Continued

Sandstone, light-gray, fine-grained to medium-grained;

forms prominent ledge ........................................................................ 55.2

Poorly exposed; scattered exposures show green and gray

claystone and siltstone ........................................................................ 11.6

Sandstone, gray, medium-grained; near base are %-in.

pebbles of chert, quartz, and quartzite ............................................ 21.4

Siltstone, greenish-gray; forms bench or recess under

overlying sandstone .............................................................................. 3.0

Sandstone, light-gray, medium-grained to coarse-grained ................ 16.0

Conglomerate, contains pebbles of quartz, quartzite, and chert

as large as 2% in. in diameter; several feet of relief on

basal contact .......................................................................................... 8.0

Sandstone, light-gray, coarse-grained, massive, feldspathic;

contains scattered pebbles of quartz, quartzite, and chert .......... 4.2

Poorly exposed; scattered exposures show varicolored claystones.... 11.6

Sandstone, light-gray, medium-grained to coarse-grained,

massive, arkosic; irregular basal contact, lowermost few

inches contains white and brown quartz and white and brown

quartzite pebbles as long as % in. .................................................... 54.2

Sandstone, light-gray, very fine grained; forms basal part

of prominent ledge ................................................................................ 2.7

Siltstone, dark-gray; light-gray claystone; forms recess ................ 2.5

Total Molina Member of Wasatch Formation ............................337.8

B3. Molina Member of the Wasatch Formation,

NWK sec. 4, T. 10 S., R. 96 W. 

Wasatch Formation, Molina Member:

Sandstone, light-brown, poorly sorted, feldspathic .......................... 11.6

Covered slope; probably claystone or shale ........................................ 25.2

Sandstone; upper one-third gray, medium grained, massive, 

poorly sorted, feldspathic; middle one-third brown, medium 

grained, thin bedded, and poorly sorted; basal one-third 

brown, medium grained to coarse grained, massive, 

poorly sorted .......................................................................................... 23.2

Covered slope; scattered exposures indicate interval is mainly 

green and gray claystone; basal part probably underlain 

by light-gray siltstone; 5 ft of relief on contact between 

this and overlying unit ........................................................................ 31.9

Sandstone, gray, fine-grained to very fine grained, calcareous; 

interbedded with claystone; lowest 2 ft contains quartz, 

chert, and quartzite pebbles in a claystone matrix ........................ 17.0

Covered slope; upper part is probably underlain by light-green 

silty claystone; lower part probably underlain by dark-green 

siltstone or very fine grained sandstone .......................................... 35.8

Sandstone; light greenish gray and fine grained to very fine 

grained at top; light brown and medium grained to fine 

grained in middle; reddish brown and medium grained at base.... 23.2

Slope; probably underlain by claystone or shale; in the 

middle is 3 ft of green very fine grained sandstone ...................... 14.5
PICEANCE CREEK BASIN, COLORADO M17

B3. Molina Member of the Wasatch Formation, NW1/* sec. 4,

T. 10 S., E. 96 W. Continued Thickneaa

(feet)

Wasatch Formation, Molina Member Continued

Sandstone, gray to brown; basal 4 ft is green conglomeratic 

sandstone containing pebbles of tan, red, and black chert, 

brown quartzite, and white quartz; remainder of unit 

contains a few pebbles ........................................................................ 13.1

Covered slope ............................................................................................ 15.0

Slope; probably underlain by green siltstone and green 

and red silty claystone ........................................................................ 23.2

Sandstone, reddish-brown with green mottling (green in basal 

part), fine-grained to medium-grained; thin zones contain 

small pebbles of red and brown chert .............................................. 29.0

Claystone, greenish-gray; forms a flat bench .................................... 4.0

Sandstone, gray, fine-grained, feldspathic; forms ledge; contains 

inclusions of green sandstone and in upper one-third a few 

quartz pebbles ........................................................................................ 16.0

Sandstone, olive-green, fine-grained to medium-grained, slightly 

calcareous; contains a few brown quartzite and black chert 

pebbles .................................................................................................... 8.5

Sandstone, light-gray, fine-grained, massive, slightly calcareous, 

ledge-forming; contains inclusions of light-green and darkgreen siltstone ........................................................................................ 5.8

Covered slope; probably underlain by light-green claystone and 

fine-grained dark-green sandstone .................................................... 17.0

Sandstone, light-green, fine-grained to medium-grained, massive, 

f eldspathic, calcareous; contains gray clay pebbles at base; 

forms prominent ledge ........................................................................ 18.4

Total Molina Member of Wasatch Formation ............................332.4

i

C. Shire Member of the Wasatch Formation, SE^A sec. 18, T. 9 S., R. 97 W.,

< and SVz sec. 18, T. 9 S., R. 96 W.

.y Wasatch Formation, Shire Member:

Claystone, red, brown, and lavender .................................................... 46.4

^ Claystone, light-purple ............................................................................ 11.0

Claystone, red, lavender, and brown, alternating .............................. 64.8

Limestone and sandstone; thin-bedded calcareous sandstone at 

top; gray medium-grained sandstone in middle; gray

' limestone at base .................................................................................. 17.4

_j Claystone, lavender and purple .............................................................. 26.1

Sandstone, gray; or limy sandstone; contains thin clay partings.... 11.4

Claystone, mostly red and brown; some lenticular sandstones ........ 30.0

Sandstone, gray, medium-grained, very calcareous ............................ 1.5

Claystone, purple; contains a few thin sandstones ............................ 16.4

Sandstone, gray, medium-grained, slightly calcareous .................... 1.5

Claystone, purple ...................................................................................... 28.5

Sandstone, gray, very fine grained, calcareous .................................. 1.5

Claystone, brown, some purple .............................................................. 98.6

 Claystone, light-purple, some gray and brown .................................. 63.8

Claystone, red, some lavender and purple ............................................ 25.2

Claystone, gray and brown .................................................................... 29.0

Claystone, light-purple ............................................................................ 11.6
M18 CONTRIBUTIONS TO STRATIGRAPHY

C. Shire Member of the Wasatch Formation, SEy± sec. 13, T. 9 S., R. 97 W., 

and Sy2 sec. 18, T. 9 S., R. 96 W. Continued Thickness (feet)

Wasatch Formation, Shire Member Continued

Claystone, brown and lavender .............................................................. 29.0

Claystone, gray and light-purple .......................................................... 29.0

Claystone, lavender and purple; brown zone in middle .................... 46.4

Claystone, gray; light-purple at base ..................................................110.5

Claystone, purple ...................................................................................... 3.0

Claystone, lavender .................................................................................. 26.1

Claystone; mostly lavender with some purple...................................... 19.3

Claystone; mostly brown with some lavender and purple ................ 52.2

Sandstone, calcareous, or sandy limestone .......................................... 1.0

Claystone; mostly lavender with some purple and some gray ........ 58.0

Sandstone, gray, fine-grained to medium-grained, thin-bedded ........ 1.0

Claystone, purple; gray near the top .................................................... 29.0

Covered slope; scattered exposures indicate slope underlain 

by lavender claystone .......................................................................... 40.6

Sandstone, calcareous, or sandy limestone .......................................... 5.6

Covered; probably underlain by claystone .......................................... 16.0

Total Shire Member of Wasatch Formation ..............................951.4

REFERENCES CITED

Donnell, J. R., 1961a, Tertiary geology and oil-shale resources of the Piceance 

Creek basin between the Colorado and White Rivers, northwestern Colorado: U.S. Geol. Survey Bull. 1082-L, p. 835-891.

 1961b, Tripartition of the Wasatch Formation near DeBeque in 

northwestern Colorado, in Short papers in the geologic and hydrologic 

sciences: U.S. Geol. Survey Prof. Paper 424-B, p. B147-B148.

Erdmann, C. E., 1934, The Book Cliffs coal field in Ga.rfield and Mesa Counties, Colorado: U.S. Geol. Survey Bull. 851, 150 p. [1935].

Gale, H. S., 1910, Coal fields of northwestern Colorado and northeastern 

Utah: U.S. Geol. Survey Bull. 415, 265 p.

Lee, W. T., 1912, Coal fields of Grand Mesa and the West Elk Mountains, 

Colorado: U.S. Geol. Survey Bull. 510, 237 p.

Patterson, Bryan, 1933, A new species of the amblypod Titanoides from Western Colorado: Am. Jour. Sci., 5th ser., v. 25, no. 149, p. 415-425.

 1934, A contribution to the osteology of Titanoides and the relationships of the Amblypoda: Am. Philos. Soc. Proc., v. 73, no. 2, p. 71-101.

 1936, Mounted skeleton of Titanoides, with notes on the associated 

fauna [abs.]: Geol. Soc. America Proc. 1935, p. 397-398.

.1939, New Pantodonta and Dinocerata from the upper Paleocene of

western Colorado: Field Mus. Nat. History Pub. 1441, Geol. Ser., v. 6,

no. 24, p. 351-384. 

Wood, A. E., 1962, The early Tertiary rodents of the family Paramyidae:

Am. Philos. Soc. Trans., 1962, v. 52, pt. 1, 261 p. 

Wood, H. E., chm., and others, 1941, Nomenclature and correlation of the

North American continental Tertiary: Geol. Soc. America Bull., v. 52,

no. 1, p. 1-48.

U. S. GOVERNMENT PRINTING OFFICE : 1969 O - 330-509