274 STANTON

Buttes invertebrate

fauna

at

about

the

same

horizon the following lists of fossilscollected

by Robert

Forrester in the

Laramie

of south- west

Colorado may be

given

Beaver Creek, T. _{34 N., R. 5} W., near boundary line between

La

Plata

and

Archuletacounties, Colorado. Coal measures immediatelyabove the Lewis shale.

Anomia

sp. Relatedto A. micronema

Meek.

ModiolalaticostataWhite.

Corbicula sp. Related toC. suhelliptica

M. &

H.

Corhicula occidenialis

M. &

^H.

Corbula undifera

Meek

Melania wyomingensis

Meek?

YellowJacket Creek,T._{34 N., R.5}W., "Coal measures above Lewisshale."

Ostrea sp.

Unioholmesianus

White

Unio hrachyopisthns White Unioverrucosiformis Whitfield?

Unio sp. Undescribed, possibly two ^species.

Ttdotoma thompsoni White

Campeloma?

sp.

Neritinasp.

Mr. James H. Gardner,

^of the

U.

S. Geological Survey,

who

has

done

detailed

work

in the region, verifies the identification of the horizonatthe localities

where

these collections

were made.

Area

west of Rawlins,

Wyoming. — ^{At Black}

^Buttesthe

^marine

^Cre-

taceous

and immediately

overlying rocks dip gentlyeastward passing

under beds

of

Wasatch, Green

River,

and

Bridger age in the

broad

syncline of the

Great

Divide Basin.

They

again

come

to the surface with a

westward

dipa

few

mileswestof

Rawlins and 60

to70 miles^east of

Black

Buttes.

A ^summary

description of the section

exposed

here

is published

by

E. Eggleston Smith,''^ to

which

the reader is referred for lithologic

and

areal details.

The

paleontologic material dis- cussed

below was

collectedinpart

by

thefieldparties ofMessrs.

Smith and

Ball

and

in part

by

myself.

The

estimates of thickness are Smith's.

The Mesaverde

formation,

which

^is coal-bearing

and about 3600

feetthick, isnot veryfossiliferous in thisarea,buta

few marine

inverte- brates

have been

obtained ⁱⁿ thelower part

and

near the top there is

*''

The

eastern part of the Great Divide Basin coalfield,

Wyoming,

Bull.

U. S. Geol. Survey, No. 341, pp. 220-242.

"CERATOPS beds" OF WYOMING AND MONTANA

275 athin

bed

^of mostly brackish-water^shells,

among which

thefollowing

have been

identified

from

a locality in

T.

22 N., R. 89

W.:

Ostrea suhtrigonalis E.

&

^S.

Ostrea glabra

M. &

^H.

Anomia

micronema

Meek

Mytilus subarcnaius

M. &

H.? Corbicula occidentalis

M. &

^H.

Mclania wyomingensis

Meek?

OdontobasisbuccinoidesWhite

Above

the

Mesaverde

^is the

Lewis

shale,

about 1500

feet thick, with

some

layers ofconcretionary sandstone

which

are often fossilif- erous. In the

township above-mentioned

these yieldedthe following

marine

^fossils:

Ostrea sp.

Modiola galpiniafia (E.

&

^S.)?

Avicula nebrascana E.

&

^S.

Syncyclonemarigida H.

& M.

Nucula

sp.

Protocardia subquadrata E.

&

^S.

Corbulasp.

Dentaliumgracile

H. & M.

Anchura

sp.

Baculites ovatus Say Scaphites nodosus

Owen

The same

fauna, with

some

additional species, such as

Avicula

fibrosa

M. & H. and Lucina

occidentalis

(Morton)

is also

found

in

calcareous concretions in the

dark

shales.

The

coal-bearing formation,

about 3900

feet thick,

conformably

overlying the Lewis, is called

Laramie

in Smith'sreport.

Near

^the

middle

of theformationin

T.

22N.,

R.

89

W.,

in lineacrossthe strike

from

the

Mesaverde and Lewis

^localities

above

recorded, Corbula suhtrigonalis

M. & H. was

collected

and

10feethigher

Tulotoma thompsoni and Campeloma

^sp.occur. Fuller collections

were

obtained

from

thisformation

from

the adjoining

township on

the south.

Here

a brackish-water

bed about 1000

feet

above

thebaseyielded

Ostrea glabra

M. &

H.

OstreasiibtrigonalisE.

&

^S.?

Anomia

micronema

Meek

Mytilus subarcuatus

M. &

^H.?

Corbicula cytheriformis

M. &

^H.

Corbiculafracta

Meek

PanopcBa simulatrix Whiteaves?

Neritinavolvilineata White

This

is evidently a recurrence with sHght modifications, of the brackish-

water fauna found

atthetopofthe

Mesaverde and

itisprac- tically identicalwith thebrackish-water elementof the

fauna

at

Black

Buttes.

Considerably higher in the section near the

middle

of the ^''Lara-

mie"

thefollowing fresh-water shells

were

obtained:

Unio goniamhonatus White

Unio

stantoni White

Unio verriicosiformis Whitfield Unio hrachyopisthus

White?

Tulotoma ^thornpsoni White Goniohasis sp.

All of these species except

one

are

found

at

Black

Buttes

and

that

one

occursat Hell

Creek and Converse County.

The

stratigraphic, areal,

and

structural relations

and

the faunal evidenceall

seem

to justify the correlation of the

"Laramie"

of this area with the

Black

Buttescoalgroup.

Above

his

Laramie Smith

recognizes

two

unconformities

between which

there are coal-bearing strata with a total thickness estimated at

8780

feet

which he

treats as ^**undififerentiated Tertiary."

The

lower partisconglomeratic,especially

about 1000

feet

above

the base,

where

the

conglomerate

contains pebbles of both Paleozoic

and

Cre- taceous rocks. Fossil plants recognized asFort

Union by Knowlton have been

obtained

from

several horizonsin this thickseries.

Above

the

upper unconformity

there are

900

^to

1800

feet of coal- bearing

beds

referred

by Smith

to the

Wasatch. The

basal con- glomerateisinlargepart derived

from

granitewith

some

sedimentary pebbles.

The most

important paleontologicevidenceas totheageof this formation consists of

some

teeth of

Coryphodon,

a

mammalian genus

characteristic of the

Wasatch, and an

unstudied flora

which

is

said to

be

different

from

the Fort Union.

The

fresh-water shells obtained alsoindicate

Eocene

later

than

Fort

Union.

Carbon

County,

Wyoming. — ^The

area adjoining that

mapped by

E. E.

Smith on

the east

and

extending

from Rawlins about

50 miles

"CERATOPS beds" OF WYOMING AND MONTANA

277 eastto

Medicine Bow had been

previously studied

by

A. C.

Veatch/*

and

as

Veatch

atfirst

had

supervisionofSmith's

work

the

same

strati-

graphic units

were

recognized

and

used in both areas.

With some

variations in thickness

and

hthologic character the

Mesaverde and

the

Lewis

of the

two

areas correspond veryclosely.

The

^"

Laramie"

ofSmith'sreport

was

called

"Lower Laramie" by Veatch and

extends

up

to the

same

unconformity, with a reported thickness of

6500

feet.

Veatch's

"Upper Laramie"

ofthisarea withtheadditionat thetopof

1200

feetof

beds

referred toFort

Union,

apparently corresponds very wellwith Smith's "undifferentiated Tertiary."

The

^"

Upper Laramie"

has a basal conglomerate^"

composed

largely of pebbles derived

from

theunderlying Cretaceous rocks"

and

inpart of the area it overlaps several of the older formations. It includes the coal

beds mined

at

Carbon, Dana, and Hanna. The

floraassoci- ated with the coal at

Carbon

has long

been known and

has

been

the subject of

much

discussion. It has usually

been

classed with the floraof

Evanston

aslaterthantheotherflorasformerlyreferredtothe

Laramie,

butthequestion

whether

^itbelongsto theFort

Union

or to

some

other flora

must

wait until the plants

have been

thoroughly restudied with fuller collections

made

with careful reference to the stratigraphy of the region.

The

invertebrate collections

from both

the

"Upper" and "Lower Laramie" have been

verymeager.

The

^localities

and

horizonsof the differentlotsasgiven

on

thefield labels

have been compared

withthe published geologic

map, and

the evidence will

be

recorded as it

stands.

A

brackish-water fauna, represented

by

Osirea

and

Corbicula,

was

collectedat severallocalities in the

"Lower Laramie" and

alsoin the

Lewis and Mesaverde. Only one

lot is

from

a locality

mapped

as

"Upper Laramie" and

that is

from

sec. 21,

T.

24 N.,

R.

81

W.,

at the lower

boundary

of the formation

where

lower

beds

are

probably

exposed.

As

brackish-water shells

have

not

been found above

this

major unconformity

^elsewhere in the region it is fair to

assume

that this lot

was

collected

below

it.

A

fresh-water

fauna

like that of

Black

Buttes is indicated

by a

"

Coalfields of east-central Carbon County,

Wyoming,

Bull. U. ^S. Geol.

Survey, No. 316, 1907, pp. 244-260.

number

of small lots

from

the

"Lower Laramie." The

^{largest of}

these,

from

sec. 16,

T.

_{24 N.,}

R. 84 W.,

contains Unio couesi White

Unio

verrucosiformis Whitfield Unio sp.

Campeloma

muUilineata

M. &

^H.

Cassiopella turricida White

At

several other localities

Tulotoma thompsoni White was

collected with the other gastropods of this list.

This

fresh-water

fauna was

collected at but

one

locality

mapped

as

"Upper Laramie." That

is in sec. 10,

T.

23 N.,

R. 80 W.,

near the contact

where "Upper Laramie"

^is overlapping

"Lower Laramie" and

Lewis,

making

it

probable that the collector

was

in error as to the line

between

the formations.

Other

localities in the

"Upper Laramie"

yielded

Unio

prisciis

M.

&

H.,

Unio

sp., Viviparus raynoldsanus

M. &

^H.,

^{and Campeloma}

muUilineata,all of

which

occur in the Fort

Union, though

the last

named

species is also widely distributed in the

Laramie and

^"Cera- tops beds."

In

this area

Hatcher"

has recordedthepresence of "

horned

dino- saurs

and

Hadrosauridae

on

the

North

PlatteRiver oppositethe

mouth

of the

Medicine Bow, about

_{35 miles}

below

Fort Steele,

Wyoming."

This

locality is

mapped by Veatch

as

"Lower Laramie" and

^itisonly

about

a mile

from

theplace(sec. 16,

T.

24 ^N.,R. 84

W.)

inthe

same

formation

where

^the fresh-water shells

above

listed

were

obtained.

Mr. Veatch

believes,however,that thedinosaurs

were found

inabluff of

"Upper Laramie" about

a mile

and

a half

above

the

mouth

of

Medicine Bow. His

belief, it is said, is

based on

statements of a resident of the region, that large ^fossils

were once

^collected there.

The

invertebrate fossils in the lower formation indicate to

my mind

that the dinosaurs

ought

to

be where Hatcher

said he

found

them, but thelocality

ought

to

be

restudied.^"

^'Am. Naturalist, Vol.

XXX,

1896, p. 118.

'"This ^is perhaps an appropriate place to record another reportedoccur- rence of dinosaurs in a high horizon. Last year Mr. James H. Gardner collected bones referred to Triceratops, Trachodon, Tyrannosaurus,etc.,near Ojo

Alamo

^onCoalCreek, northwestern

New

Mexico, atalocalitywhereMr.

Barnum Brown

had previously found dinosaurs. Mr.Gardner believes that thebed from which he collectedbelongstothe Puerco and that it is several

CERATOPS BEDS OF WYOMING AND MONTANA

₂₇₉