Upper Cretaceous Pelecypods 

of the Genus Inoceramus 

from Northern Alaska

By DAVID L. JONES and GEORGE GRYC

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-E

A description of Jive species which are important 

guide fossils to the Upper Cretaceous rocks of 

the midwestern interior of North America 

and northern Alaska

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1960
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

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

Washington 25, D. C. - Price 45 cents (paper cover)
CONTENTS

Page

Abstract _________________________________________ 149

Introduction _______________________________________ 149

Cretaceous rocks.__________________________________ 149

Upper Cretaceous rocks _____________________________ 150

Nanushuk group (part)_________________________ 150

Colville group.________________________________ 150

Page 

Age and correlation_ ____----_-_____--______-----__- 152

Geographic distribution_____________________________ 153

Systematic descriptions_____________________________ 158

Literature cited-______________--_--_--___-___--_-__ 162

Index._________-_-__-__-----_------------_-------_ 165

ILLUSTRATIONS

[Plates 15-23 follow page 167J

PLATE 15. Inoceramus (Inoceramus) dunveganensis McLearn.

16. Inoceramus (Inoceramus) dunveganensis McLearn.

17. Inoceratrus (Inoceramus) dunveganensis McLearn.

18. Inoceramus (Inoceramus) dunveganensis McLearn and Inoceramus aff. /. (Inoceramus) cuvierii Sowerby.

19. Inoceramus aff. /. (Inoceramus) cuvierii Sowerby, Inoceramus (Inoceramus) dunveganensis McLearn, Inoceramus (Mytiloides) labiatus (Schlotheim), and Inoceramus (Sphenoceramus) steenstrupi de Loriol.

20. Inoceramus (Mytiloides) labiatus (Schlotheim) and Inoceramus (Inoceramus) dunveganensis McLearn.

21. Inoceramus (Inoceramus) dunveganensis McLearn and Inoceramus (Sphenoceramus) patootensis de Loriol.

22. Inoceramus (Sphenoceramus) patootensis de Loriol.

23. Inoceramus (Sphenoceramus) steenstrupi de Loriol and Inoceramus (Sphenoceramus) patootensis de Loriol.

Page 

FIGITRE 30. Diagrammatic sections showing terminology and relationship of Cretaceous lithologic units in northern Alaska._ 151

31. Age of formations and fossil sequence__________________________________________________________________ 153

32. Correlation of Cretaceous formations. ______________________________________--_--_-___---------------__ 154

33. Index map of the Colville River region showing /nocerawws-bearing localities.___-_________--_-___-__-----__ 155

TABLES

TABLE 1. Geographic distribution of Inoceramus in northern Alaska_--------__----------------------_-------------- 156

2. Inoceramus-beariug localities in the Upper Cretaceous rocks of the Colville River region. ____________________ 156

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

UPPER CRETACEOUS PELECYPODS OF THE GENUS INOCERAMUS FROM NORTHERN ALASKA

By DAVID L. JONES ancl GEORGE GRYC

ABSTRACT

Upper Cretaceous rocks in the Colville River region of 

northern Alaska contain a fauna consisting of five species 

of Inoceramus, all of which are known from other localities, 

either in the United States, Canada, Europe, or elsewhere. 

Associated fossils include a small number of pelecypod species, 

a few species of gastropods, and several species of ammonites. 

The species of Inoceramus range in age from Cenomanian to 

late Santonian or early Campanian, but none are of Coniacian 

age.

Upper Cretaceous rocks in the Colville River region are 

divided into three formations, which are, in ascending order, 

the Ninuluk, the Seabee, and the Schrader Bluff. Inoceramus 

(Inoceramus) aunveganensis McLearn, of Cenomanian age, is 

abundant in the Ninuluk formation. Inoceramus (Mytiloia'cs) 

labiatus (Schlotheim) and I. aff I. (Inoceramus) cuvierii 

Sowerby occur in the lower part of the Seabee formation of 

early Turonian age. Inoccramus aff. /. (7.) cuvierii occurs 

alone in the upper part of the Seabee, which probably is of 

middle to late Turonian age. There is no evidence that this 

species extends into the Coniacian in northern Alaska. The 

Barrow Trail member of the Schrader Bluff formation contains 

Inoceramus I SpJtenoceramus) patontensis de Loriol and I. 

I iSf.) steenstrupi de Loriol, both of late Santonian to early 

Campanian age. The precise age of the lower and upper members of the Schrader Bluff formation is not certain.

INTRODUCTION

Before 1943 the geology of northern Alaska was 

known only from exploratory and reconnaissance 

surveys. Schrader (1902 and 1904) made the first 

geologic traverse of the region and mapped the geology 

along the Anaktuvuk and lower Colville Rivers. Later 

Collier (1906), Leffingwell (1919), ancl Smith and 

Mertie (1930) made major contributions to the geology 

of northern Alaska. These studies indicated the 

presence of extensive deposits of fossiliferous Cretaceous rocks, but little stratigraphic detail was recorded 

and few fossils were collected. Several occurrences of 

Inocentmuft are noted in the reports of Schrader, 

Leffingwell, and Smith and Mertie.

In 1943 the U.S. Geological Survey renewed its 

mapping activities in northern Alaska in suppcH of 

the U.S. Navy's program to explore Naval Petroleum 

Reserve No. 4 and determine the petroleum possibilities 

of the region. This program began in 1944 and was 

suspended in 1953. The Survey cooperated in all the 

geologic aspects, including detailed and semide/ailed 

mapping of nearly all the bedrock exposures. Many 

Cretaceous fossils from several hundred localities were 

collected. Several species of Inoceramus and the general sequence of Cretaceous faunas were reported by 

Gryc, Patton, and Payne (1951).

This study of the subfamily Inoceraminae from 

northern Alaska is based on collections made from 

1944 through 1953. The collectors include: Robert S. 

Bickel, William P. Brosge, Robert R. Coats, Robert L. 

Detterman, Robert E. Fellows, George Gryc, Charles 

E. Kirschner, Allan N. Kover, Richard G. Ray, Karl 

Stefansson, Lawrence A. Warner, and Edward J. 

Webber.

The stratigraphic relationships, locality descriptions, 

and positions of localities on figure 31 have been 

prepared primarily by William P. Brosge, Robert L. 

Detterman, George Gryc, and Charles L. Whittington.

In the following text, Jones discusses the fossils 

and interregional correlations. Gryc describes the 

formations and their stratigraphic relations.

CRETACEOUS ROCKS

Upper Cretaceous rocks were first recognized and 

mapped in northern Alaska along the Anaktuvuk River 

by Schrader. The age of these rocks was determined 

from the presence of the ammonite Scaphites and 

several pelecypods, including Inoceramus (Schrader, 

1904, p. 80). Smith and Mertie (1930) added descrip149
150 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

tions of the lithologic characteristics and distribution 

of the Upper Cretaceous rocks but did not define 

formations.

After the U.S. Navy began its oil exploration program in the Arctic, detailed stratigraphic information 

was rapidly accumulated and a formational nomenclature was developed. In May 1951, Gryc, Patton, 

and Payne published the first formal definitions and 

descriptions of Upper Cretaceous formations in 

northern Alaska. A summary of the geology of the 

Arctic Slope and further stratigraphic details were 

published by Payne and others later that year. In 

February 1956, Gryc and others revised the stratigraphic terminology for the Mesozoic sequence in the 

Colville River region (fig. 30). In November 1956, 

Sable extended the use of part of this terminology 

to northwestern Alaska.

Upper Cretaceous rocks and Lower Cretaceous rocks 

of Albian age, constitute a stratigraphic sequence that 

rests with marked angular discordance on older Cretaceous (Neocomian, Okpikruak formation) and preCretaceous rocks.

Lower Cretaceous rocks (fig. 30) include up to 

12,000 feet of predominantly marine shale, and up to 

1,000 feet of graywacke sandstone. The Tuktu formation (Albian) is overlain to the south by the nonmarine 

Chandler formation and to the north by the predominantly marine Grandstand formation. The contact of the Tuktu with the overlying units is marked 

by white quartz in the sandstone. The Lower Cretaceous formations defined in the outcrop belt cannot 

be readily distinguished lithologically in the subsurface 

of the coastal plain. Thus two subsurface units, the 

Oumalik and Topagoruk formations have been defined 

(Robinson, and others, 1956).

UPPER CRETACEOUS ROCKS 

NANUSHUK GBOUP (PABT)

The position of the Lower Cretaceous-Upper Cretaceous contact in northern Alaska has been in question 

for several years. The next highest readily mappable 

unit above the ridge-forming Lower Cretaceous Tuktu 

formation is the black shale of the Upper Cretaceous 

Seabee formation, which overlies the coarser sedimentary rocks of the Ninuluk formation or, to the 

south, the Niakogon tongue of the Chandler formation. 

Because of the apparent depositional continuity from 

the Tuktu to the base of the Seabee, this sequence was 

defined as the Nanushuk group (Gryc and others 1951, 

p. 162). In 1954 Imlay and Reeside (p. 243) stated,

At the top of the Nanushuk group in the foothills of the 

Brooks Range abundant Inoceramus have been found in marine 

intercalations in the Niakogon tongue of the Chandler formation. The common species include /. athabaskensis McLearn 

and I. dunveffanensis McLearn. These have been identified 

elsewhere in Alaska in the lower part of the Upper Cretaceous 

sequence * * *.

These "marine intercalations" have since been defined by Detterman (1956, p. 241, 242) as the Ninuluk 

formation of Late Cretaceous age. At the type locality 

it is 657 feet thick. In the northern part of the outcrop 

area and in the subsurface of the coastal plain the 

Ninuluk formation overlies beds of the Grandstand 

formation which contain a Lower Cretaceous microfauna. In these areas the Lower Cretaceous-Upper 

Cretaceous contact can be determined. However, in 

the southern part of the outcrop area, the Ninuluk 

formation overlies nonfossiliferous Hds of the 

Chandler formation and the lower limit of the Upper 

Cretaceous sequence is indeterminate. Imlay (1960) 

has described the Lower Cretaceous megafauna and 

Tappan (written communication) is studying the 

microfauna. The megafossils are commonly associated 

with red-weathering conglomeratic sandstone.

Sable (1956) applied the name NamiFhuk group to 

rocks in northwestern Alaska but stated that precise 

correlations with the formations of the Colville River 

region cannot be made. Sable described two formations, the Kukpowruk and the Corwin, in the UtukokCorwin area (fig. 30) and gives the age as "late Early 

and Late Cretaceous, not older than middle Albian" 

(Sable, 1956, p. 2641).

COLVILLE GBOUP

The Colville group unconf ormably overlies the Nanushuk group. Whittington states (1956, p. 244),

The group consists of a sequence of intertonguing marine 

and non-marine rocks and is about 5,500 fe^t thick in the 

type section. Northward and eastward non-marine units 

become thinner and tend to disappear. Rock types include 

clay shale, claystone, silt shale, siltstone, sandstone, conglomerate, bentonite, tuff, coal, clay ironstone, and limestone * * * 

Bentonite and tuff are much more prevalent than in the 

Nanushuk group.

The Seabee formation, about 1,500 feet thick at the 

type locality, marks the base of the Colville group. 

It is divided into two units: an unnamed member and 

the Ayiyak member (Detterman, 1956). The unnamed 

member is characterized by thick units of black, oilshale which, when weathered, commonly splits into 

paper-thin sheets. Fossiliferous, thin beds, lenses, and
UPPER CRETACEOUS PELECYPODS OF THE GENUS INOCERAMUS FROM NORTHERN ALASKA 151

Utukok-Corwin

area 

(after Sable, 1956)

Colville River Region 

(modified from Gryc and others, 1956)

South Arctic foothills North Arctic coastal plain

Prince

Creek

formation

 UNCONFORMITYCor win 

formation

Kukpowruk 

formation

Kogosukruk 

tongue Sentinel Hill 

member of Schrader 

Bluff formation

Prince

Creek

formation

Barrow Trail member 

of Schrader Bluff 

formation

Schrader

Bluff 

formation

Rogers Creek 

member of 

Schrader Bluff 

formation

Unnamed member of Seabee formation

.UNCONFORMITY^

Niakogon 

tongue

Chandler^ 

formation

Tuktu 

formation

Torok and Fortress 

Mountain formations

Okpikruak 

formation

Torok and Fortress 

Mountain formations

Okpikruak 

formation

Seabee 

formation

Topagoruk

formation

(subsurface)

Oumalik

formation

(subsurface)

Lower Cretaceous (?) 

and Upper 

Jurassic (?) rocks 

undiff ere ntiated

PL. 

&

o 

« 

o

5

O 

O

FIGURE 30. Diagrammatic sections showing terminology and relationship of Cretaceous lithologic units in northern Alaska.
152 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

concretions of limestone are common. Fossils are also 

common in the shale but are mostly crushed and poorly 

preserved. The sandy beds in the upper part of the 

formation contain a similar, but more limited fauna 

and were defined as the Ayiyak member by Detterman 

in 1956.

The marine Schrader Bluff formation (approximately 2,300 ft. thick) overlies the Seabee formation 

with apparent unconformity. The Schrader Bluff has 

been divided into three members, the Rogers Creek, 

Barrow Trail, and Sentinel Hill (Gryc and others, 

1951, p. 166; Whittington, 1956, p. 250-251). Fossils 

have been found in all three but are abundant only 

in the middle member and are commonly associated 

with a very fine grained tuffaceous sandstone.

The Prince Creek formation is the approximate 

nonmarine equivalent of the Schrader Bluff and 

probably part of the upper part of the Ayiyak 

member of the Seabee formation. The Prince Creek 

is about 1,700 feet thick and is subdivided into the 

Tuluvak tongue and the Kogosukruk tongue, which is 

the top unit in the Upper Cretaceous sequence in 

northern Alaska.

East of the Anaktuvuk-Colville Rivers, the Upper 

Cretaceous is imconformably overlain by the Tertiary 

Sagavanirktok formation (Gryc and others, 1951, p. 

167). West of the Anaktuvuk-Colville Rivers, no 

Tertiary beds have been identified and the Gubik 

formation of Pleistocene age imconformably overlies 

the Cretaceous. The Gubik also extends to the east 

where it overlies the Sagavanirktok formation.

AGE AND CORRELATION

The species of Inoceramus collected from the Colville 

River region are known also from Alberta, British 

Columbia, and other parts of Canada, as well as from 

the western interior of the United States. Several of 

the species also occur in England, Greenland, and 

northern Europe, and one species, /. (Mytiloides) 

labiatus. has worldwide distribution.

The number of species of Inoceramus found in 

northern Alaska is very small compared with that 

found in Cretaceous rocks of the same age in the 

western interior of the United States and in southern 

Canada. Likewise, many of the ammonites that 

characteristically are associated with the extensive 

Inocerctmus faunas of the western interior are missing 

in northern Alaska. Inoccnnnux (Inoceramus} dunvegciHensix is typically a northern species. The southern known limit of this species is in Montana. InocerMytUoidex] labiatus is known throughout the 

world, and is not indicate of any faunal province. 

Inoceramus (Sphenoceramux) patootemk and /. ($.) 

steenstrupi are both northern species, occurring in 

Canada, the western interior of the United States, 

Greenland, England, Germany, and elsewhere. /. (7.) 

cuvierii has a wide distribution, but seems most 

typically to be a northern species. Although the 

Inoceramus fauna from the Colville River region has 

strong affinities with the western interior of the United 

States and Canada, and with the faunas of northern 

Europe, it shows very little relationship to the 

Inoceramus of the Indo-Pacific faunal province, known 

from southwestern Alaska, Vancouver Island, British 

Columbia, California, Japan, and elsewhere. With 

exception of /. fab lotus and possibly /. cuvierii, no 

species of Inoccramus from northern Alaska is known 

to occur in the Indo-Pacific Province.

The oldest species of Inoceramus known from the 

Upper Cretaceous rocks of the Colville River region 

is /. dunveganenxis McLearn, s. 1., whicl occurs in the 

Ninuluk formation. As herein interpreted, this species 

ranges from late Albian to late Cenomanian (fig. 31). 

No ammonites have been found in the Colville River 

region in association wit/i /. dunveganensis, so it is 

impossible to determine precisely the upper and lower 

age limits of the Ninuluk formation, o** to locate the 

Lower and Upper Cretaceous boundary in this area. 

The Ninuluk is probably nearly equivalent to the 

Belle Fourche shale of the western interior of the 

United States and the Dunvegan formation of British 

Columbia, both of which are believed to be Cenomanian in age (fig. 32).

The Seabee formation, which unconformably overlies the Ninuluk formation, contains a fauna consisting of Inoceramus (Mytiloides) Jabiatus (Schlotheim), /. aff. /. (/.) cuvierii Sowerby, Watinoceras 

sp., Scaphites sp>, and Borissiakoceras (Borissjakocerax] sp. /. fabiotus seems to be restricted to rocks 

of early Turonian age. In the westem interior of 

the United States, this species is very abundant in the 

Pfeifer shale member of the Greenhorn limestone, and 

also occurs in the overlying Fairport chalky member 

of the Carlile shale (zone of Coilingnoniceras woollgari) (William A. Cobban, oral communication.) 7. 

cuvierii Sowerby in England ranges from about 

middle Turonian to late Santonian. In North 

America, 7. aff. 7. cuvierii ranges from the zone of 

Coltignoniceras hyatti to the zone of Scaphites
UPPER CRETACEOUS PELECYPODS OF THE GENUS INOCERAMUM FROM NORTHERN ALASKA 153

Age of formations

1

OT

02

CRETACEOl

 §

03

,

1

I

European stages

Maestrichtian

Campanian

Santonian

Coniacian

Turonian

Cenomanian

Albian

Rock units

COLVILLE GROUP

fc

S

w

£

-

J Sentinel Hill 

=S member

5

4J Barrow Trail 

2 member

M

Rogers Creek 

member

'y/y///,.

Seabee formation

. > ^ -"~~ ~-*f >^ ^ ~ *

. . ^~_^ * i_~<-

Ninuluk formation

Grandstand 

formation

Topagoruk 

formation 

(subsurface)

Oumalik formation 

subsurface)

/>v'- x -v

/.- '- / - ' /'/ <

Fossil sequence

No fossil evidence for late 

Campanian age

Inoceramits patootensis and 

Inoceramus steenstrupi

No fossil evidence for early 

Santonian age

No fossil evidence for Coniacian age

Inoceramus aff. I. fuvieni, 

Watinoceras sp., Scaphites sp. 

and Borissjakoceras sp.

Inoceramus labiatus

Inoceramus dunveganensis

FIGURE 31. Age of formations and fossil sequence.

corvenxix (middle to late Turonian), but lias not 

been found above the Turonian. The genus TVatinocertis is restricted to the lower Turonian according ~ to

Wright (1957, p. L416). Morrow (1935, p. 465) reports species of Borisxjakoceras from the Graneros 

shale (late Cenomanian) and the Blue Hill shale 

member of the Carlile shale (early Turonian) in 

Kansas. All this evidence indicates that the unnamed member of the Seabee formation is probably 

early Turonian, and is a correlative of the upper part 

of the Greenhorn limestone and possibly the lower 

part of the Carlile shale of the western interior. If 

this correlation is correct, /. cuvierii may have a 

slightly lower range in North America than it does 

in Europe.

The Ayiyak member of the Seabee formation contains only Inoceramus aff. /. cuvierii, and is probably 

the correlative of the upper part of the Carlile shale 

(late Turonian). There are no indications that the 

upper part of this member extends into the Coniacian.

The Schrader Bluff formation overlies the Seabee 

formation with apparent conformity, but strata of 

Coniacian age may be missing and an unconformity 

may separate the two formations. In northeastern 

British Columbia, McLearn and Kindle (1950) report a fauna! sequence consisting of Watinoceras cf. 

W. coloradoense Henderson and Inoceramus labiatus 

from the Smoky group, followed by /. pontoni and 

ScapJiites ventricosus in the Kotaiieelee formation, 

with /. cf. /. tuberculatus Woods (equals /. steenstrupi 

de Loriol) in the upper part of the formation. This 

faunal sequence is similar to that of the CoVille 

River region, except that the Scaphites ventricosus 

fauna has not been found in northern Alaska. The 

age of Scaphites ventricosus in the western interior 

of the United States is about middle Coniacian, and 

the absence of this species in the Colville Jliver 

region suggests that some Coniacian strata may be missing. The upper limit of the Seabee formation is not 

known, and no diagnostic fossils are known from the 

Rogers Creek member of the Schrader Bluff formation. Either one, or both, of these units may be, in 

part, of Coniacian age.

The Barrow Trail member of the Schrader Bluff 

formation contains Inoceramus (Sphenoceramus') 

patootensis de Loriol and /. (S,} steenstrupi de Loriol 

of middle Santonian to early Campanian age. ^hese 

two species are also known from Canada, Greenland, 

England, Germany, and elsewhere. No fossilr are 

available to date the overlying Sentinel Hill member. 

The Schrader Bluff is probably Santonian to early 

Campanian in age, and is nearly equivalent to the 

upper part of the Niobrara formation, the Telegraph 

Creek formation, the Eagle sandstone, and possibly 

the lower part of the Pierre shale of the western interior of the United States.

GEOGRAPHIC DISTRIBUTION

The occurrence by locality and formation of the 

species of Inoceramus described in this report is 

shown on table 1.

The general position of each locality is shown on 

figure 33.

Detailed descriptions of the localities, as we 1 ! as 

stratigraphic data, are given in table 2,

527586 O - 60 - 2
154 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

UOI^BUUOJ jmjg

« .-3 * 6

J £ = i

\l

dnojS uqof -}g ^ao

dnojS uqof ';

UOIJBUUOJ

BJBjqoifj
FIUURK 33. Index map of the Colville River region showing Inoceramus bearing localities.
156 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 1. Geographic distribution of Inoceramus in northern 

Alaska

[X indicates present]

USOS Mesozoic 

locality (fig. 33)

20465..----- --.-.

20467. ..._____-_____.

20476. _______________

20419_. ............ __

25148_____... ________

25140.. ______________

24268_____. _._.__

24276_.__ _ ______

24283-___----------

24284_. ___._._...____

24285_. ______________

24300_. ______________

24271_. ..............

24629_. ______________

24630.. ______________

19435_. _ ___________

20413- ___ 

20420_. _._._.___.___.

26549. ._.._._________

26560_. _._.._.__.____

26566 - _- .

24641_. ______________

26568.. ....... _______

26569. .___._-_._____.

26533. _______________

24632_. ___.._._.____.

19434_. ______________

20461. ______-___-_-__

20462.. _____________

20481.. -

20493-- 

26504. __..__._____._.

26508_. ___-_.__.__._.

26509. . ______________

26511..-.... . ..

26515___. ___-_._._.__

26516_._____ _ ______

26518_. ______________

26519... ._..____-__..

26521_. ...... _..__. __

26525. .___._.__..___.

26526_. ___.___...___.

/. (Inoceramus) dunpeganensis

1 

XXXXXXXXXXXXXXXXXXXXXXX

7. (Mytiloides) 

labiatus

XXXXXXXXXXXX

7. aff. 7. 

(7.) cuvierii

X

X 

X

X 

X 

X

7. (Sphenoceramus) 

patootensis

X 

X 

X 

X 

X

X

X 

X 

X 

X 

X 

X 

X 

X 

X?

7. (Sphenoceramus) 

steenstrupi

X 

X 

X 

X

X

X

TABLE 2. Inoceramus-bearing localities in the Upper Cretaceous rocks of the Colville River region

USOS 

Meso- Field No. Stratigraphic 

zoic loc. position 

(fig. 33)

Locality, lithology, and collector

Ninuluk formation, 657 ft thick at type locality

20465. __ 45AWa97 _ Basal part of 

formation.

20466- _ _ 45AWa82.-. 10 ft above base

20467. _ 45AWal22.._ Basal part of 

formation.

20468-. 45AWal23A. 10 ft above base

Colville River, south bank, lat 69°04'30" 

N., long 153°41' W. Sandstone and 

conglomerate. 'Collector, W. A. 

Warner, 1945. 

Killik River, northeast bank about 10 

miles upstream from Colville River, 

lat 68°59' N., long 153°36'30" W. Same 

locality as 24629. Collector, W. A. 

Warner, 1945. 

Colville River, south bank, lat 69°08' NT ., 

long 153°18' W. Same locality as 

25148. Sandstone float. Collector, 

W. A. Warner, 1945. 

Colville River, south bank, same locality 

as 20467. Collector, W. A. Warner, 

1945.

TABLE 2. Inoceramus-ftramiflr localities in the Upper Cretaceous 

rocks of the Colville River region Continued

USGS 

Mesozoic loc. 

(fig. 33)

Field No. Stratigraphic 

position

Locality, lithology, and collector

Ninuluk formation, 657 ft thick at type locality Continued

20476- . 

20418---

20419- - -

25154-.-

25155--- 

25140. _ . 

24264- -

24268- __ 

24276.-.

24278 ... 

24283. - _ 

24284. - 

24285. - - 

24300 _

46ARylOOB . 

46ARyl25E

47ADU07 -- 

47ADtl58 

47ADtl63--_ 

48ADt215--_ 

52AB145-...-

52AB1181... . 

52ADt32.--_

52AD174---. 

52ADU02-- 

52ADU55A52AD1168- - - 

52ADt230-_.

420 ft above 

base.

Basal 100 ft of 

formation.

600-650 ft 

below top.

Probably same 

as 20418.

100 ft above 

base.

Near base of 

formation.

Basal part of 

formation.

Basal 100 ft 

of formation.

Basal part of 

formation

Near base of 

formation.

Base of formation.

Middle of formation.

100-150 ft above 

base.

Basal 100 ft of 

formation.

Basal part of formation.

Basal part of formation.

Colville River, south bank, lat 69°08' N., 

long 153°18' W. Collector, C. E. 

Kirschner, 1945. 

Colville River, south bank-, lat 69°08' N., 

long 153°15' W. Sandstone. Collector, 

C. E. Kirschner, 1945. 

Weasel Creek, 2.5 miles southwest of 

confluence with Maybe Creek, lat 

69°13' N., long 153°58' W. Cut bank 

on east side of stream, poorly exposed 

massive to slabl y sandstone, 50-60 

ft thick. Collecto-, R. G. Ray, 1946. 

On an unnamed stream 1.6 miles southeast of its confiience with Maybe 

Creek, lat 69°15'30" N., long 153°33' 

W. Cut bank on northeast side of 

stream imperfectly exposing about 100 

ft of sandstone with subordinate shale 

and coal. Fossils occur in talus. Collector, R. G. Ray, 1946. 

Colville River, south bank, lat 69°08' N., 

long 153°18' W. Thin-bedded sandstone. Collector, R. L. Detterman, 

1947. 

On ridge south of tributary of Ninuluk 

Creek, lat 69°11' N., long 153°02' W. 

Sandstone and conglomerate. Collector, R. L. Detterman, 1947. 

Colville River, north bank, lat 69°13'30" 

N., long 153°03' W. Interbedded sandstone, siltstone, a^d clay shale. Collector, R. L. Detterman, 1947. 

Chandler River, east bank, lat 68°49'15" 

N., long 151°57'30" W. Sandstone and 

conglomerate. Collector, R. L. Detterman, 1948. 

On ridge west of Ayiyak River, lat 

68°57'30" N., long 152°28' W. Green 

to yellow-red sandstone. Collector, 

R. S. Bickel, 1952. 

Anaktuvuk River, lat 68°55' N., long 

151°11'30" W. Collector, R. S. Bickel, 

1952. 

Wolverine Creek, east bank of east fork, 

lat 68°45' N., long 152°22' W. Massive 

conglomerate and sandstone. Collector, R. L. Detterman, 1952. 

On ridge top, lat 68°59'30" N., long 

152°51' W. Medium-bedded, saltand-pepper sands'one. Collector, R. 

L. Detterman, 1952. 

On ridge south of Ayiyak River, lat 

68°55' N., long 152°23' W. Mediumbedded gray sandstone. Collector, 

R. L. Detterman, 1952. 

Anaktuvuk River, west bank, lat 

68°56'30" N., long 151°10'30" W. Sandstone and conglomerate. Collector, 

R. L. Detterman, 1952. 

Anaktuvuk River, west bank, lat 68°51' 

N., long 15l°08' W. Thick-bedded 

sandstone. Collector, R. L. Detterman, 1952. 

On hillside about 1 mile from small tributary of Ninuluk Creek, lat 69°05'30" 

N., long 152°38' W. Thin-bedded 

greenish sandstone. Collector, R. L. 

Detterman, 1952.
UPPER CRETACEOUS PELECYPODS OF THE GENUS INOCERAHUti FROM NORTHERN ALASKA 157

TABLE 2. Inoceramus-bearing localities in the Upper Cretaceous

rocks of the Coli'ille River region Continued

USGS

Mesozoic loc.

(fig. 33)

Field No. Stratigraphic

position

Locality, lithology, and collector

Ninuluk formation, 675 ft thick at type locality Continued

24271. __

24629. _ _

24630. _ -

52AB1273____

53ADt62_...

53ADt84_...

L ower part of

formation.

Basal 10 ft of

formation.

Basal 10 ft of

formation.

On ridge east of small tributary of Fossil

Creek, lat 69°07' N., long 152°36' W.

Thin-bedded green sandstone. Collector, R. S. Bickel, 1952.

Killik River, northeast bank, about 10

miles upstream from Colville Rivei,

lat 69°59' N., long 153°36' W. Thickbedded, ferruginous sandstone. Collector, R. L. Detterman, 1953.

Colville River, north bank, about 4 miles

downstream from Killik River, lat

69°04' N., long 153°52' W. Thickbedded ferruginous sandstone and conglomerate, same as 24629. Collector, 

R. L. Detterman 1953.

Seabee formation, Unnamed member, 250-1,250 ft thick

19435. ..

20424.__

20413. _ _

20413. _.

20420___

26545. _.

26549. _.

26560...

26563 __

26565- _.

26566 . _ _

24641

44AC525-.--

46ASt3______

46ARy68a.._

46ARyfi8b___

46ARyl31.__

47AWh63__.

47AWbl77__

49 A Bel. ...

51AQr34____

52ADt57___.

52ADt61_.._

52AB131..___

375-550 ft above

base.

Same as 19435. _.

180ft below top. _

180 ft below top255-265 ft below

top.

About 850 ft below top.

About 1,100 ft

below top.

255-265 ft below

top.

60-100 ft below

top.

160 ft below top..

130 ft below to p. _

20-30 ft below

top.

Bluff on north side Colville River at

Umiat Mtn., lat 69°23'30" N., long

152° W. Dark fossiliferous shale with

dark fossiliferous calcareous concretions and many light-colored bentonite laminae and thin beds. Forms conspicuous black cliff. Collector, R. R. 

Coats 1944

Location and lithology same as 19435.

Collector, K. Stefansson, 1946.

Maybe Creek, north bank, 3.75 miles 

above mouth of September Creek, lat

69°19' N., long 154°19' W. Float of

gray-brown fine-grained calcareous

sandstone. Collector, R. G. Ray, 1946.

Location and lithology same as 46-

ARy68a. Collector, R. G. Ray, 1946.

Maybe Creek, north bank, 1.5 miles

above mouth of Anak Creek, lat 69°16'

N., long 153°47' W. Dark-gray limestone concretions in black shale. Collector, R. G. Ray, 1946.

Nanushuk River, west bank, lat

68°50'30" N., long 150°33' W. Bentonitic clay shale and limestone concietions.

Collector, E. J. Webber, 1947.

Nanushuk River, west bank, lat 69°03'

N., long 150°51' W. Black paper shale

and limestone concretions. Collector,

E. J. Webber, 1947.

Lat 69°16' N., long 153°47' W. Same as

20420. Collector, W. P. Brosge, 1949.

Tuluga River, east fork, north bank, lat

68°50'45" N., long 151°25' W. limestone concretions in shale. Collector,

G. Gryc, 1951.

Ayiyak River, east hank, lat 68°51'30"

N., long 152°36' W. Interbedded silty

shale, clay shale, siltstone, and sandstone. Collector, R. L. Detterman,

1952.

Ayiyak River, east bank, lat 68°52' N.,

long 152°33'30" W. Siltstone, silty

shale and clay shale. Collector, R. L.

Detterman, 1952.

Ayiyak River, east bank, lat 68°52'30"

N., long 152°32' W. Bentonitic clay

shale and thin, green sandstone. Collector, R. S. Bickel, 1952.

TABLE 2. Inoceramus-bearing localities in the Upper Cretaceous

rocks of the Colville River region Continued

USGS

Mesozoic loc.

(fig. 33)

Field No. Stratigraphic

position

Locality, lithology, and collector

Seabee formation, Unnamed member, 250-1,250 ft thick Continued

26568...

26569 -.

52AB133-..

52AB1259-__.

Near contact with

Ayiyak member.

400-450 ft below

top.

Ayiyak River, east bank, lat 68°53' N.,

long 152°30'30" W. Bentonitic clay

shale and green sandstone. Collector,

R. S. Bickel, 1952.

On small tributary of Chandler River,

lat 69°02'15" N., long 151°58' W. Bentonitie black paper shale and limestone

concretions. Collector, R. S. Bickel,

1952.

Seabee formation, Ayiyak member, 360 ft thick at type locality

26533 ..

24632 -.

47AWb264__

53ADH16

130 ft below top__

300 ft below top..

Nanushuk River, west bank, lat 69°04'

N., long 150°50' W. Interbedded sandstone, siltstone, silt, and clay shale.

Collector, E. J. Webber, 1947.

Nanushuk River, west bank, lat 68°50'30"

N., long 150°32'30" W. Greenish-yellow sandstone and conglomerate. Collector, R. L. Detterman, 1953.

Schrader Bluff formation, Barrow Trail member. 700-900 ft thick

19434. _

20461 - _ .

20462. - _

20463-.-

20481. ..

20493 _ _ .

26498. _ _

26504 . _ _

26508 __

26509

26511- __

44AC522_-_-

45AGrl95.__

45AGr200. _ _

45AGr201_ ..

45AFsll6f...

45AFs29 .

47AWbl36__

47ADt293- . .

48ADt387_ _ .

48ADt410

48ADt449- . .

325-355 ft below

top.

250-350 ft above

base.

200-300 ft above

base.

Same as above. _

Upper 600 ft .

Exact position

not known.

Lower 120ft_.___

220 ft below top. _

80- 150 ft above

base.

540-600 ft above

base.

900-1,040 ft

above base.

Colville River, south side, prominent

bluff near Umiat, about 7 miles southwest of Umiat Mtn., lat 69"29' N.,

long. 152°15' W. Seven-inch conglomerate and 25-foot tuffaceous sandstone. Collector, George Gryc, 1944.

Chandler River, west bank at mouth of

Kutchik River, lat 69°19' N., long

151°25' W. Tuffaceous sandstone.

Collector, George Gryc, 1945.

Chandler River, west bank, lat 69°20' N.,

long 151°25' W. Light buff sandstone.

Collector, George Gryc, 1945.

Same as above.

Anaktuvuk River, east bank at f chrader

Bluff, lat 69°10' N., long 150° W.

Tuffaceous sandstone and s'ltstone.

Collector, R. E. Fellows, 1945.

Anaktuvuk River, east bank, le.t 68°29'

N., long 151°17' W. Collector, R. E.

Fellows, 1945.

Nanushuk River, northeast bank, lat

68°59'15" N., long 150°42' W. Laminated, tuffaceous sandstone. Collector, E. J. Webber, 1947.

Colville River, south bank at out 3.6

miles southwest of Umiat, lat 69°20'30"

N., long 152°15' W. Tuffaceous sandstone. Collector, R. L. Detterman,

1947.

Chandler River, east bank, lat e9°12'15"

N., long 151°26'30" W. Tuffaceous

sandstone, siltstone, and clav shale.

Collector, R. L. Detterman, 1S48.

Chandler River, east bank, lat 69°13' N.,

long 151°25'30" W. Tuffaceous siltstone, silty shale, clay shale. Collector, R. L. Detterman, 1948.

Chandler River, west bank at the junction of Kutchik River, lat e9°19'l5"

N., long 151 °25' W. Siltstone and silty

shale. Collector, R. L. Detterman,

1948.

527586 O - bO - 3
158 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 2. Inoceramus-6earzn</ localities in the Upper Cretaceous 

rocks of thf Colville River region Continued

rsos

Mesozoic loc.

(fig. 33)

Field No. Stratigraphic

position

Locality, lithology, and collector

Schrader Bluff formation, Barrow Trail member, 700-900 ft thick Continued

2651 5_

26516.

26518.

26519. _ _

26521. . .

26525___

26526-

52ADtl75_

52ADtl76^_-

52AB1194___

52AB1195__-_

52AB1197-.,,

52AB1202....

52AB1203_.._

500-520 ft above

base.

550-560 ft above

base.

670 ft above

base.

630 ft above

base.

430-450 ft above

base.

430-450 ft above

base.

500-530 it above

base.

Outpost Mtn., north side, about 1 .5 miles

west of Tuluga River, lat 69°10'30"

N., long 151°08'45" W. Tuflaceous

sandstone. Collector, R. I . Detterman, 1952.

Outpost Mtn., about 1 mile southwest

of 26515, lat 69°09'30" N., long 151°10'

W. Tuflaceous sandstone. Collector,

R. L. Detterman, 1952.

Outpost Mtn., south side, about 1 mile

southwest of 26515, lat 69°09' N., long

151°09' W. Tuflaceous sandstone and

siltstone. Collector, R. S. Bickel,

1952.

Outpost Mtn., about 0.3 mile west of

26518, lat 69°09' N., long 151°10' W.

Tuffaceous siltstone. Collector, R. S.

Bickel, 1952.

Outpost Mtn., about 0.5 mile west of

26518, lat 69°09' N., long 151°10'45"

W. Tuffaceous siltstone. Collector,

R. S. Bickel, 1952.

Outpost Mtn., lat 69°09'15" N., long

151°14'30" W. Tuffaceous sandstone

and siltstone. Collector, R. S. Bickel,

1952.

Outpost Mtn., lat 69°09'30" N., long

151°13'30" W. Tuflaceous sandstone.

Collector, R. S. Bickel, 1952.

SYSTEMATIC DESCRIPTIONS

Class PELECYPODA

Family ISOGNOMONIDAE Iredale

Subfamily INOCERAMINAE Zittel, 1881

Genus INOCERAMUS Sowerby, 1814

1814. Inoceramiis Sowerby, Annals Philosophy, p. 448.

Type species: Inoceramus cuvierii Sowerby, 1814. 

(International Commission on Zoological Nomenclature 

decision pending.)

Subgenus INOCERAMUS

Type species: Inoceramm cuvierii Sowerby, 1814. 

Inoceramus aff. I. (Inoceramus) cuvierii Sowerby, 1814 

Plate 18, figure 3 ; plate 19, figures 1, 5. 

1814. Inoceramus cuvierii Sowerby, Annals Philosophy, p.

448.

1912.

?1930.

Inoceramus lamarcki var. cuvieri Sowerby. Woods, 

Paleontographical Soc., v. 65, p. 307-327, pi. 53, 

fig. 7; text figs. 78-83. (See Woods' paper for 

complete synonymy up to 1912.)

Inoceramus allani Warren, Research Council Alberta, 

Kept. 21, app., p. 62, pi. 3, fig. 1.

Shell equivalve, very inequilateral, subquadrate, 

moderately inflated, height 1 greater than length;

1 Height is measured from the dorsal margin to the ventral margin ; 

length is measured from the anterior margin to the posterior margin ; 

width is measured normal to the plane of the valves.

beaks anterior, incurved; hinge line moderately long, 

forming angle greater than 90° with anterior margin; 

posterodorsal area compressed to form wing; anterior 

margin truncated, straight to concave, and may extend 

anteriorly beyond position of beaks; ventral margin 

broadly rounded; posterior margin slightly rounded. 

Ornamentation consists of rounded, fairly prominent, 

unsymmetrically curved, concentric ribs which are 

marked by more than one growth line. This type of 

concentric ribbing that carries multiple growth lines 

was named Anwachsreifen (growth bands) by Heinz 

(1928b,p. 1-39).

Woods (1912, p. 307-327) has shown that Inoceramus cuvierii varies greatly in the prominence of the 

concentric ribs, the degree of convexity of the valves, 

the size of the posterior wing, and the angle formed 

between the hinge line and the anterior margin. Most 

of the northern Alaskan specimens ar? poorly preserved and fragmentary, but they agree with Woods1 

illustrations of /. cuvierii in general outline and 

convexity of the valves, the presence of the posterior 

wing, and in the Anwachsreifen type of ornamentation. The specimen illustrated by Warren (1930, p. 

62, pi. 3, fig. 1) as /. allani has not been examined 

by the writer, but as Warren's figure agrees very well 

in general shape and outline with Woods1 (1912, p. 

315, text fig. 73) illustration of the type of /. cuvierii, 

it is tentatively regarded as a synonym of /. cuvierii. 

Warren's species seems to have less prominent ornamentation, but this probably is not significant.

Inoceramus aff. /. cuvierii is reported by Cobban 

(oral communication} from the Carlile shale (upper 

Turonian) of the western interior of the United 

States. According to Donovan (1953, p. 93; 1954, 

p. 17), poorly preserved specimens with ornamentation 

said to be similar to that of /. cuvierii occur in deposits 

of Turonian age in Greenland. There is no evidence 

that /. aff. /. cuvierii extends above tl Q Turonian in 

North America or Greenland.

The range of Inoceramus cuvierii in England is, 

according to Woods (1912, p. 332), from the zone of 

TerebrafitUna lata, (middle Turonian) to the zone of 

Micraster coranguinum (lower Santonian). In northern Alaska, /. aff. /. cuvierii occurs with /. labiatus 

in the upper part of the unnamed member of the 

Seabee formation, and it is found along throughout 

the overlying Ayiyak member. The age of /. labiatus 

is probably early Turonian, so possibly the lowest 

limit of /. cuvierii is slightly lower in northern Alaska 

than it is in England. The Ayiyak member is probably late Turonian in age and possibly, in part, early 

Coniacian, but no fossils are present to establish a 

more precise age.
UPPER CRETACEOUS PELECYPODS OF THE GENUS INOCERAMUS FROM NORTHERN ALASKA 159

r of specimens: 33 (mostly fragments).

Figured specimens: USNM 2 129226, 129227, 129228.

Localities: Unnamed and Ayiyak members of Seabee formation; USGS Mesozoic Iocs. 20413, 24632, 26533, 26560, 26563, 

26569.

Inoceramus (Inoceramus) dunveganensis McLearn, 1926 

Plate 15, figures 1-13; plate 16, figures 1-5; plate 17, figures 

1-5; plate 18, figures 1, 2, 4; plate 19, figures 2, 4; plate 20, 

figures 2, 3, 6; plate 21, figures 1-4, 6.

1926. Inoceramus dunveganensis McLearn, Canada Dept. 

Mines, Geol. Ser. 45, Bull. 42, p. 122, pi. 20, fig. 5.

1930. Inoceramus mcconnelli Warren, Research Council Alberta, Rept. 21, app., p. 60, pi. 4, figs. 1-3.

1931. Inoceramus nahwisi McLearn, Royal Soc. Canada

Proc. & Trans., ser. 3, v. 25, p. 7, pi. 2, fig. 1. 

1943. Inoceramus atliabaskensis McLearn, The Canadian

Field Naturalist, v. 57, p. 44. 

1943. Inoceramus nalncisi var. goodricliensi* McLearn, idem,

p. 45. 

?1943. Inoceramus nanicisi var. ntoberliensis McLearn, idem,

p. 46. 

1945. Inoceramus atJiabaskensis McLearn, Canada Geol.

Survey Paper 45-27, pi. 2, fig. 10; pi. 5, fig. 1;

pi. 6, fig. 1. 

1945. Inoceramiis dunreganensis McLearn, idem, pi. 2, fig.

11; pi. 4, figs. 1, 2.

1945. Posidonomya nalncisi (McLearn), Canada Geol. Survey Paper 44-17, pi. 9, figs. 1, 2; pi. 10, fig. 1. 

1945. Posidonomya naJiwisi var. goodrichensis (McLearn),

idem, pi. 10, fig. 3; pi. 11, figs. 4, 5. 

71945. Posidonomya nahirisi var. mo'berliensis (McLearn),

idem, pi. 10, fig. 7. 

1945. Inoceramus diinreganensis var. mcconneUi Warren,

McLearn, idem, pi. 3, fig. 2.

Shell equivalve (?), very inequilateral, height 

greater than length, slightly oblique, moderately convex; anterior margin nearly straight to broadly 

rounded, compressed in some specimens to form anterior wing; ventral margin broadly and regularly 

rounded; posterior margin slightly rounded; posterodorsal area compressed to form wing; hinge line short 

to moderately long, forming angle of more than 90° 

with anterior margin; ornamentation consists of 

coarse, distantly spaced, rounded, irregular, concentric 

ribs which are generally more prominent on anterior 

and posterior parts of the valves than on central 

portion, where ribs may be completely lacking. 

Growth axis forms angle of 80° to 90° with hinge line.

The posterior adductor muscle scar is slightly 

behind the median line of the valves. (See pi. 15, 

figs. 6, 8, 12, 13; pi. 16, figs. 3, 5; pi. 21, fig. 2.) The 

anterior adductor muscle scar is not visible; apparently, this muscle was greatly reduced in size. A 

series of disconnected attachment scars extends in a 

broad curve from near the posterior adductor muscle

* United States National Museum.

scar to the anterior part of the umbo. The purpose 

of these attachment scars is not known, but presumably they served as attachments for the mantle.

MacLearn's and Warren's original descriptions of 

Inoceramus dunveganensis, I. athabaskensis, /. nahwisi and its varieties, and /. mcconnelli were based 

on very few specimens. The much larger collections 

from northern Alaska, consisting of 107 specimens, 

show that the holotypes of their species are only 

isolated examples of one variable species, and that 

transitions exist between all the holotypes, except 

possibly for /. nahwisi moberUensis, Therefore, all 

these specimens are included under the oldest name, 

/. dunveganensis McLearn. This species is actually 

not as variable as many other species of Inoceramus. 

The main variations observed in /. dunveganensis s. I. 

are:

Height of valves: The specimens range in height 

from 1 inch to more than 15 inches and distinct size 

groups cannot be recognized. This range in size 

seems to be a normal characteristic of Inoceramus, and 

differentiation of species on the basis of size alone 

is not valid.

Ratio of length of hinge line to height of valve: 

This ratio ranges from about 0.2 to more than 0.4, 

(pi. 16, figs. 2, 5; pi. 17, fig. 2) but clearly defined 

groups with either a short hinge line (near 0.2) or 

a moderately long hinge (near 0.4) are not recognizable.

Ratio of width of valve to height of valve: The 

width and height of the valves cannot be measured 

accurately because complete specimens are rarely preserved. However, approximate measurements show 

a transition between specimens with a ratio of width 

to height of about 0.5 to specimens with a ratio of 

about 0.8. None of the specimens have a ratio of 

1.0 or greater.

Degree of rounding of the anterior mat-gin and 

presence of an anterior wing: These features cannot 

be measured accurately and expressed numerically. 

The curvature of the anterior margin is extremely 

variable, not only among specimens, but also in the 

growth stages of an individual. During early growth 

stages, the anterior margin is nearly straight, truncated, and forms an angle of about 90° with the 

hinge line (pi. 15, figs. 1-10). After a height of 1 

to 2 inches or more, the anterior marginal area becomes flat and new shell material is added tc form 

a broadly rounded skirt (pi. 15, fig. 13; pi. 16, figs. 

3, 5). In some specimens this skirt is very wide and 

projects anteriorly beyond the beaks to form an 

anterior wing (pi. 20, fig. 6; pi. 21, fig. 1, 6); in 

other specimens the skirt is narrow and no wing is
160 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

formed (pi. 18, figs. 1, 2; pi. 20, fig. 2). Thus, the 

degree of development of the anterior wing is variable, and its presence or absence is not of specific 

importance in this species.

Ornamentation: The ornamentation consists of 

rounded, concentric ribs which generally are more 

prominent on the anterior and posterior sides than 

on the central part of the valve (pi. 15, fig. 13; pi. 17, 

fig. 1; pi. 20, fig. 6). However, in some specimens 

the ribs formed during early growth stages continue 

without diminishing in prominence across the central 

part of the valve, and only those ribs formed in later 

growth stages are interrupted (pi. 15, fig. 12; pi. 16, 

fig. 5). Other specimens lack ribs when small, but 

develop them as the shell becomes larger. Inoceramus 

mcconnelli Warren, which is similar in shape and 

outline to /. dunveganfnsis s. 7.. has this type of 

ornamentation.

Obliquity of the valves: The angle between the 

hinge line and the axis of growth (the line connecting 

'he point of maximum curvature of successive concentric ribs) ranges from about 80° to 90° in all of 

the specimens studied, including the holotypes of 

McLearn's Inoceramus dunveganensis^ I. atJiabaskensis, I. nahwisi and /. naJiwisi goodrichensis. and of 

Warren's /. mcconnelli. However, /. naliwisi moberliensis has a growth angle of about 60° during its 

early stages, and an even smaller angle in later stages 

(pi. 21, figs. 3, 4). None of the specimens from 

northern Alaska have as small an angle, so it cannot 

be shown that the specimens with large angles are 

transitional into those with smaller angles. Therefore, 

/. nahirisi moberliensis is only tentatively regarded as 

a synonym of /. dunveganensis. If this oblique type 

can be shown to have stratigraphic significance, the 

name probably should be retained.

In northeastern British Columbia, McLearn and 

Kindle (1950, p. 82, 84, 93) report the occurrence of 

Inoceramus naliwisi goodrichensis in the Goodrich 

formation, and the ammonite Neogastroplites, of latest 

Albian or earliest Cenomanian age (see Reeside, 1957, 

table 1, opposite p. 540). /. dunveganensis s. s., /. 

athabaskensis, and /. mcconnelli occur in the Dunvegan formation in northeast British Columbia in association with ammonite Dunveganoceras (see McLearn and Kindle, 1950, p. 99; McLearn, 1943, fig. 1), 

which, according to Reeside (1957, table 1, opposite 

p. 540), is restricted to the upper Cenomanian. As 

the author can find no morphologic basis for separating any of these species, /. dunveganensis is interpreted 

as ranging in age from late Albian to middle or late 

Cenomanian.

/. dunveganensis occurs in the western interior of 

Canada, in the Nirmluk formation of northern Alaska, 

and also in the sandy beds that are equivalent to the 

Mowry shale of Montana (J. B. Reeside, Jr., oral 

communication). One questionable occurrence is also 

reported in the Kuskokwim region of Alaska (USGS 

Mes. loc. 19388).

Number of specimens: 107.

Figured Specimens: USNM 129210, 129211, 129212, 129213, 

129214, 129215, 129216, 129217, 129218, 129219, 129220, 129221, 

129222, 129223, 129224, 129225. Plastotypes C^S 3 6106, 6344, 

8937, 8945, 8938, 9710, 9713, 9811, 9813, 9816, 9317. Plastotype 

Univ. Alberta CT 417, CT 418.

Localities: Ninuluk formation, USGS Messazoic Iocs. 20418, 

20419, 20465, 20466, 20467, 20468, 20475, 20476, 20488, 24264, 

24267, 24268, 24271, 24276, 24278, 24283, 2428*, 24285, 24300, 

24629, 24630, 25140, 15148, 15154, 25155.

Submenus MYTILOIDES Brongniart, 1822 

Type species: Inoceramus labiatus (Schlotheim).

Inoceramus (Mytiloides) labiatus (SchlotMim), 1813

Plate 19, figure 3; plate 20, figures 1, 4, 5.

1813. Ostracises labiatus Schlotheim, Leonard, Taschenbuch 

fiir Mineralogie, v. 7, p. 93 (fide Woods, 1911, p. 281). 

(For synonymy to 1911, see Woods, 1911, p. 281).

Shell mytiliform, nearly equivalve, moderately inflated, extremely inequilateral, oblique, height much 

greater than length; beaks anterior, slightly incurved; 

hinge line short to medium in length and generally 

forms an angle of less than 90° with anterior margin; 

anterior margin broadly rounded, posterior margin 

nearly straight. Ornamentation consist? of low, fairly 

regular, rounded, concentric ribs.

Inoceramus labiatus s. 1. is found throughout the 

world in deposits of Turonian age. Specimens show 

much variation in the length of the Huge line, the 

angle formed between the anterior margin and the 

hinge line, the convexity of the valves, and the degree 

of posterior obliquity. Unfortunately, no worldwide 

study of this species has been made in sufficient detail 

to ascertain if geographic or stratigraphic subspecies 

exist. Seitz (1935) recognized five srbspecies of /. 

labiatus, but the validity of his work is questioned 

because none of his published samples contains more 

than eight specimens, which is not a sufficient number 

to show adequately the range of variation.

According to Woods (1911, p. 283), Inoceramus 

labiatus in England is found mainly in the zone of 

Rhynchonella cuvierii (early Turonian), but it also 

occurs in the zone of Terebratulina lata (late Turonian). In Germany Heinz (1928a, pi. 3) and Andert

3 Geological Survey Canada.
UPPER CRETACEOUS PELECYPODS OF THE GENUS INOCERAMUS FROM NORTHERN ALASKA 161

(1934, p. 41) record /. labiatus only from the lowermost 

Turonian beds. This species is also common in the 

uppermost part of the Greenhorn limestone and its 

equivalents in the western interior of the United 

States where, according to Cobban and Reeside (1952, 

p. 1018), it occurs with the early Turonian ammonites 

Thomasites and Yascoceras. Thus, /. labiatus is a 

Turonian species, and perhaps is confined to lower 

Turonian beds, but such a restricted range has not 

been conclusively proved.

Number of specimens: 54.

Figured specimens: USNM 129229. 129230, 129231, 129232.

Localities: Unnamed member of Seabee formation; USGS 

Mesazoic Iocs. 19435, 20413, 20420, 20424, 24641, 26545, 26549, 

26560, 26563, 26565, 26566, 26568.

Subgenus SPHENOCERAMUS Boehm, 1915

Type species: Inoceramus cardissoides Goldfuss, 

1836.

Inoceramus (Sphenoceramus) patootensis de Loriol, 1883

Plate 21, figure 5; plate 22, figures 1-3; plate 23. figure 3.

1877. Inoceramus lobatus Goldfuss, Schiilter, Palaeontographica, v. 24, p. 275, pi. 39, figs. 1, 2.

1883. Inoceramus patootensis de Loriol, Medd. on Gronland, 

v. 5, no. 4, p. 211.

1918. Inoceramus patootensis de Loriol, Ravn, Medd. om 

Gronland, v. 56, p. 337, pi. 5, fig. 1; pi. 6. figs. 1-2.

1929. Inoceramus lundbreckensis McLearn, Canada Nat. Mus. 

Bull. 58, p. 77, pi. 15, fig. 4; pi. 16, fig. 2.

1936. Inoceramus patootensis de Loriol forma typica Beyenburg, Deutsche geol. Gessell. Zeitschr., v. 88. no. 2, 

p. 107. < See Beyenburg's 1936 paper for more complete synonymy up to 1936.)

1936. Inoceramus patootensis de Loriol var. anffusta Beyenburg, idem, p. 110, pi. 25, fig. 4.

1953. Inoceramus (Splienoceramus) patootensis de Loriol, 

Donovan, Medd. om Gronland, v. 3, no. 4, p. 95.

1955. Inoceramus lobatux (lohlfiiss, Cobban, Billings Geol. 

Soc. Guidebook, 6th annual field conf., p. 207, pi. 4.

Shell equivalve ( ?), very inequilateral, moderately 

inflated, oblique, divided into a V-shaped, inflated, 

anterior part and a compressed, sharply distinct, 

posterodorsal wing; height much greater than length; 

hinge line moderately long, forming an angle of 90° 

or more with anterior margin; beaks anterior, sharply 

pointed; anterior margin straight, long, truncated; a 

shallow furrow extends obliquely from behind beaks 

to posteroventral margin; posterior side of furrow 

bounded by an oblique, narrow ridge or line of nodes. 

Ornamentation on V-shaped portion consists of concentric ribs of two sizes: small, closely spaced, rounded 

ribs, and larger, distantly spaced, very irregular ribs; 

concentric ribs have unsymmetrical curvature where 

they cross the posterior furrow; ornamentation on 

wing less prominent and more regular than on

V-shaped part; small, radial riblets may occur on 

inflated, central part of valve; nodes formed along 

anterior margin, on ridge bordering the furrow, and 

along dorsal margin of posterior wing.

Inoceramus patootensis has been identified by many 

writers as /. lobatus Goldfuss, but their interpretation 

of /. lobatus was based upon specimens illustrated by 

Schliiter (1877, pi. 39, figs. 1, 2), not by Goldfuss (1836, 

pi. 110, fig. 3). Goldfuss based /. lobatus on one small, 

crushed-, apparently juvenile specimen, and it is cmestionable whether this species is recognizable. Schliiter's 

specimens are well preserved and adequately illustrated, and there is little question about the identity 

of his species. A comparison of a plaster cast of 

Goldfuss"1 type with specimens very similar to 

Schliiter's types indicates that the two species are 

probably distinct. The distinction between /. lolatus 

Schliiter and /. lobatus Goldfuss was previously 

pointed out by Stolley (1916, p. 72-73), Heinz (1928a, 

p. 79), Riedel (1931, p. 653), Beyenburg (1936, p. 

107), and others. Heinz first recognized that /. lobatus 

Schliiter and /. patootensis de Loriol are identical, and 

he applied de Loriol's name to Schliiter's species.

Beyenburg (1936, p. 107-111) split Inoceramus patootensis into five varieties, as follows: /. patootensis 

forma typica; media Beyenburg; angusta Beyenburg; 

lingua Goldfuss; and cancellata Goldfuss.

Of these varieties, angusta is unnecessary as it falls 

within the range of variation of 7. patootensis. On 

the other hand, /. lingua seems to be distinct from 

/. patootensis as its ribbing is regular throughout. 

The variety media seems -to be more closely associated 

with /. lingua than with /. patootensis* and /. cancell atits may fall within the range of variation of 7. 

cardissoides Goldfuss.

A study of large collections of 7. patootensis and 7. 

lingua may indeed show a transition between the two 

species. So far, this transition has not been demonstrated so it seems best to keep the two species seps rate. 

If a transition is shown to exist, the name 7. patootensis 

must be rejected as a synonym of 7. lingua; Beyenburg's designation of 7. lingua as a variety of 7. 

patootensis was done without regard for priority of 

names. If 7. cancellatus is also found to fall within 

the range of variation of 7. patootensis, the name 7. 

cancellatus should have priority over 7. lingua as it 

has line precedence (Goldfuss, 1836, p. 113).

Inoceramus patootensis is common in northern 

Europe, Greenland, and the western interior of Forth 

America. According to Woods (1912, p. 302), in 

England this species probably occurs in the zone of 

Actinocamax quadratus (early Campanian). Eiedel 

(1931, p. 653) reports that in Germany this species
162 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

has a range from late Santonian to early Campanian. 

In North America, Cobban (1955, p. 207) has shown 

that /. patootensis (equals /. lobatus} is an excellent 

guide fossil to the uppermost part of the Colorado 

shale, the Telegraph Creek formation, and the Eagle 

sandstone. Its range is through the ammonite zones 

of Desmoscapliites erdmanni, Desmoscaphites ~bassleri< 

and Scapliites hippocrepis (middle Santonian through 

early Campanian). Thus, on the basis of the presence 

of /. patootensis, the age of the Barrow Trail member 

of the Schrader Bluff formation is between middle 

Santonian to early Campanian.

'Num'ber of specimens: 20.

Figured xpccimens : USNM 129233, 129234, 129235, 129236; 

National Museum Canada 9037.

Localities: Barrow Trail member of Schrader Bluff formation; USGS Mesozoic Iocs. 19434, 20461, 20462, 20463, 20481, 

26498, 26508, 26509, 26511, 26515, 26516, 26518, 26519, 26521, 

26525.

Inoceramus (Sphenoceramus) steenstrupi de Loriol, 1883

Plate 19, figure 6; plate 23, figures 1, 2.

1883. Inoceramua steenstrupi de Loriol, Medd. om Grdnland,

v. 5, no. 4, p. 211. 

1912. Inoceramus tulierculatiix Woods, Paleontographical Soc.,

v. 65, p. 302, pi. 54, fig. 8; text fig. 59. 

1918. Inoeeramufi steenatrupi de Loriol, Ravn, Medd. om

Gronland, v. 56. p. 336. pi. 5, fig. 2. 

1931. Inoccramufi stcenntrupi de Loriol, Riedel, Preussisclie

geol. Landesanstalt Jahrb., v. 51, p. 660. (See

Riedel's paper for complete synonymy up to 1931.) 

1953. Inncernmna (RphenoccramuN) steenstrupi de Loriol,

Donovan, Medd. om Grc'inland, v. 3, no. 4, p. 95.

The specimens of Inoceramus steenstrupi from 

northern Alaska are fragmentary and the identification of this species is based on the characteristic 

tuberculate ornamentation. Earn (1918, p. 336-337) 

described topotype material from Patoot, Greenland, 

as follows:

Shell very large, slightly convex, very inequilateral. Height 

greater than length. Ornamentation consists of numerous 

strong, but comparatively narrow, concentric ribs, separated 

by rather wide interspaces. The ventral slope of the ribs 

steeper than the dorsal slope. In the middle part of the shell 

the ribs are crossed by radial furrows, so that the ribs appear 

to consist of rows of tubercles; in the spaces between the ribs 

these furrows are indistinct or quite absent.

The northern Alaska specimens clearly show the 

strong concentric ribs and the tubercles on the central 

part of the valve. Although none of the specimens 

are complete and nothing is known about the hinge 

line or the general shape and outline of the valves, 

the name Inoceramus steenstrupi can be applied to 

these fragments with reasonable assurance 011 the 

basis of the tubercles alone. Xo other species is known

to have this type of ornamentation so prominently 

developed.

The degree of development of the tubercles on /. 

steenstrupi is variable; some specimens have very 

large, protruding tubercles (pi. 23, fig. 1), but others 

have small and inconspicuous tubercles (pi. 19, fig. 6; 

pi. 23, fig. 2). Possibly a transition exists between 

/. steenstrupi with tubercles and /. patootensis without tubercles, but large collections of eacl species must 

be studied before this question can be answered.

Woods (1912, p. 302) states that Inoceramus tuberculatus Woods (equals /. steenstrupi} occurs in England in the zone Actinocamax quadratus (early Campanian) along with /. lobatus (equals /. patootensis}. 

In Germany Riedel (1931, p. 626) indicates that /. 

steenstrupi occurs stratigraphically below /. patootensis in beds of Santonian age. In Greenland and 

northern Alaska, /. patootensis and /. steenstrupi 

occur together (see Eavn, 1918, p. 336-337) and are, at 

least in part, of the same age. Thus, tH range of /. 

steenstrupi is probably about the same as the range 

of /. patootensis, that is, from middle Santonian to 

early Campanian.

dumber of specimens : 8.

Figured specimens: USNM 129237, 129238, 129239.

Localities : Barrow Trail member of Schrader Bluff formation; USGS Mesozoic Iocs. 20481, 20493, 2649H, 26504, 26521, 

26526.

LITERATURE CITED

Andert, Hermann, 1934, Die KreideablagerMigen zwischen 

Elbe und Jeschken, pt. 3 Die Fauna der obersten Kreide 

in Sachsen, Boehmen und Schlesien: Freussische geol. 

Landesanstalt Abb... Neue Folge, no. 159, p. 1-477, 19 pis.

Arkell, W. J., Kumniel, Bernhard, and Wright, C. W. Mesozoic 

Ammonoidea in Joint Committee on Invertebrate Paleontology, Treatise on Invertebrate Paleontology, part L 

Mollusca 4: Geol. Soc. America and Univ. Kansas Press.

Beyenburg, Edmund, 1936, Neue Fossilfunde aus dem 

Untersenon der Westfiilischen Kreide: Deutsche geol. 

Gesell. Zeitschr., v. 88, no. 2, p. 104-115, 2 pis.

Cobban, W. A., 1955, Some guide fossils frrm the Colorado 

shale and Telegraph Creek formation, northwestern 

Montana: Billings Geol. Soc., Guidebook, 6th annual field 

conf., p. 198-207, 4 pis.

Cobban, W. A., and Reeside, J. B., Jr., 1952, Correlation of the 

Cretaceous formations in the western interior of the 

United States: Geol. Soc. America Bull., v. 63, p. 1011-1044.

Collier, A. J., 1906, Geology and coal resources of the Cape 

Lisburne region. Alaska: U.S. Geol. Survey Bull. 278 p.

Detterman. R. L., 1956, New and redefined nomenclature of 

Nanushuk group: Am. Assoc. Petroleum Geologists Bull., 

v. 40, no. 2, p. 233-244.

Donovan, D. T., 1953, The Jurassic and Cretaceous stratigraphy and paleontology of Trail O, East Greenland: 

Medd. om Gronland, v. Ill, no. 4, p. 1-150. 25 pis.

 1954, Upper Cretaceous fossils from Traill and Geographical Society Oer, East Greenland: Medd. om Gronland, v. 72, no. 6, p. 1-33, 3 pis.
LITERATURE CITED 163

Goldfuss, G. A., 1836, Petrefacta Germaniae, v. 2.

Gryc, George, 1951, "Paleontology," in T. G. Payne and others,

Geology of Arctic Slope U. S. Geol. Survey Oil and Gas

Inv. Map OM 126. 

Gryc, George, Patton, W. W., and Payne, T. G., 1951, Present

Cretaceous stratigraphic nomenclature of northern

Alaska: Washington Acad. Sci. Jour., v. 41, no. 5. 

Gryc, George, and others, 1956, Mesozoic sequence in Colville

River region, northern Alaska: Am Assoc. Petroleum

Geologists Bull., v. 40, no. 2, p. 209-254. 

Heinz, Rudolf, 1928a, Das Inoceramen-Profll der oberen Kreide

Ltineburgs : Niedersaehsische geol. Yer. [Hannover] Jahrb.,

no. 21, p. 65-81, 2 pis. 

 1928b, Ueber die bisher wenig beachtete Skulptur der

Inoceranien-Shale: Hamburg min.-geol. Staatsiust. Mitt.,

no. 10, p. 1-39. 

Imlay, R. W., 1960, Lower Cretaceous megafossils from

northern Alaska: U.S. Geol. Survey Prof. Paper 335, 74 p. 

Imlay, R. W., and Reeside, J. B., Jr. 1954, Correlation of the

Cretaceous formations of Greenland and Alaska: Geol.

Soc. America Bull, v. 65, p. 233-246.

Lefflngwell, B. de K., 1919, The Canning River Region, northern Alaska: U.S. Geol. Survey Prof. Paper 109, 251 p. 

De Loriol, Percival, 1883, Om Fossile Saltvandsdyr fra

Nordgronlaud: Medd. om Groiiland, v. 5, no. 4, p. 203-213. 

McLearn, F. H., 1943, Trends in some Canadian Cretaceous

species of InoreraniHx: The Canadian Field Naturalist,

v. 57, p. 36-46, 1 fig.

McLearn, F. H., and Kindle, B. D., 1950, Geology of northeastern British Columbia: Canada Geol. Survey Mem.

259, 236 p., 16 figs., maps. 

Morrow, A. L., 1935, Cephalopods from the Upper Cretaceous

of Kansas: Jour. Paleontology, v. 9, no. 6, p. 463 473, pis.

49-53, text figs. 1-8. 

Payne, T. G. and others, 1951, Geology of Arctic Slope of

Alaska : U.S. Geol. Survey Oil and Gas Inv. Map, OM-126. 

Ravn, J. P. J., 1918, De marine Kridtaflejringer i Yestgronland

og deres Fauna: Medd. om Gronlaiid, v. 56, p. 313-336,

5 pis.

Reeside, J. B., Jr., 1957, Paleoecology of the Cretaceous seas 

of the western interior of the United States: Geo1 . Soc. 

America Mem. 67, p. 505-542, 21 figs.

Riedel, Leonhard, 1931, Zur Stratigraphie und Faciesbildung 

im Oberemscher am Siidrande des Beckens von munster: 

Preussische geol. Landesanstalt Jahrb., v. 31, p. 605-713, 

8 pis., 6 text figs.

Robinson, F. M., Rucker, F. P., and Bergquist, H. R., 1956, 

Two subsurface formations of Early Cretaceous Age: Am. 

Assoc. Petroleum Geologists Bull., v. 40, no. 2, p. 223-233.

Sable, B. G., 1956, New and redefined Cretaceous formations in 

western part of northern Alaska: Am. Assoc. Petroleum 

Geologists Bull., v. 40, no. 11, p. 2635-2643.

Schliiter, Clemens, 1877, Zur Gattung Inoceramus: Palreontographica, v. 24, p. 248-290, 4 pis.

Schrader, F. C., 1902, Geological section of the Rocky Mountains in northern Alaska : Geol. Soc. America Bull., v. 13, 

p. 233-252.

 1904, A reconnaissance in northern Alaska : U.S Geol.

Survey Prof. Paper 20, 139 p. 

Seitz, Otto, 1935, Die Yariabilitat des Inoceramus labistus v.

Schloth.: Preussische geol. Landesanstalt Jahrb., v. 55,

no. 1 (fur 1934), p. 429-474, 5 pis., 9 figs., 9 diagrams. 

Smith, P. S., and Mertie, J. B., Jr., 1930, Geology and nnneral

resources of northwestern Alaska: U.S. Geol. Survey

Bull. 815. 351 p. 

Stolley, Ernst, 1916, Neue Beitrage zur Kenntnis der norddeutschen oberen Kreide. I-IV: Niedersaehsische geol.

Yer. [Hannover] Jahrb., p. 69-108, 5 pis. 

Warren, P. S., 1930, New species of fossils from Smoky River

and Dun vegan formations, Albert: Alberta Research

Council Geol. Survey Rept. 21, p. 57-68, 5 pis. 

Woods, Henry, 1911, A monograph of the Cretaceous Lamellibranchia of England, v. 2, pt. 7, Inoceramus: Palaeontographical Soc., v. 64, p. 261-284, pis. 45-50.

 1912, A monograph of the Cretaceous Lamellibranchia

of England, v. 2, pt. 8, Inoceramus: Palaeontographical

Soc., v. 65, p. 285-340, pis. 51-54. 

Whittington, C. L., 1956, Revised stratigraphic nomenclature

of Colville group: Am. Assoc. Petroleum Geologists Bull.,

v. 40, no. 2, p. 244-253.

5Z7586 O - 60 - 4

INDEX

[Italic numbers indicate descriptions]

Page 

Actinocamax gitadratus- --- _.__.---- __. 161,162

allani, Inoceramus. ______..__--__..... 158

Anak Creek area-.-...___......_-.___ 157

Anaktuvuk River area,............... 149,152,156,157

Anwachsreifen (growth bands)------____ -_ 158

Arctic Slope, geology- ___.______..___ 150 

athabaskensis, Inoceramus... ____..._.... 150,

159,160; pis. 15-17,19 

Ayiyak River area...__._______...__ 156,157

bassleri, Desmoscaphttes........___. . 162

Belle Fourehe shale, stratigraphic relations__ 152 

Borissiakoceras, occurrence...______..__ 152,153

cancellatus, Inoceramus.--.-.......-...---....-. 161

cardissotdes, Inoceramus....... ______.-.--_. 161

Carlile shale, Blue Hill shale member---........ 153

Fairport chalky member. _.__-_.......... 152

fossil content--.--.._...___.-.-__ 158

Chandler formation, Niakogon tongue.---.,__ 150

stratigraphic relations-. ___.... ____ 150

Chandler River area......_----..----.---.-. 156,157

Collignoniceras hyatti-. ......................... 152

wooflgari.. ................................ 152

coloradoense, Watinoceras...........------------ 153

Colorado shale, fossil content...,.-_.___.. 162 

Colville River area.......... 149,150, 152,153,156-158

coranguinum, Micraster......................... 158

corvensis, Scaphites.. .__._.__....._........ 153

Corwin formation, of Sable.._.....__...... 150

cuvierii, Inoceramus.... ....................... 153,156

Inoceramus (Inoceramus)--... .. 152, 158; pis. 18,19

Phynchonella............................... 160

Desmoscaphites bassleri---....................... 162

erdmanni ....................__......._ 162

dunveganensis, Inoceramus-.....-............. 150,160

Inoceramus (Inoceramus)--. 152.156, 159; pis. 15-21

Dunvegan formation, fossil content.--.......... 160

stratigraphic relations. _-.-_-.__.___-.__ 152

Dunveganoceras, occurrence ..._______...... 160

Eagle sandstone, fossil content._._.......... 162

stratigraphic relations._......_.-__._.--_--_ 153

erdmanni, Desmoscaphites.-.._.......__... ..__. 162

Fossil Creek area._........__.-..--....... 157

Fossil localities............... 156-158,159,160,161,162

Geology of northern Alaska, history. _ __ __.. 149

goodrichensis, Incceramus nahwisi... 159,160; pis. 19, 21 

Grandstand formation, stratigraphic relations.. - 150 

Graneros shale, fossil content-....-_.......... 153

Greenhorn limestone, Pfeifer shale member.._ 152 

Gubik formation, stratigraphic relations...-_. 152

hippocrepis, Scaphites.................. ......... 162

hyatti, Ccllignoniceras... ............._._.... 152

Indo-Pacific faunal province._....____..... 152

Inoceraminae, subfamily, fossil collections...... 149

Inoceramus allani...... ...__................. 158

associated ammonites.-...--._.._....... 152

athabaskensis........ .... 150.159,160; pis. 15-17,19

cancellatus-. ................._........... 161

cardissoides ................................ 161

cuvierii-..-....................... ....._.. 153,156

Page 

Inocframus Continued

dunveganensis-............................ 150,160

from Cretaceous rocks.... 149,150,152,153,156-158

holotypes.-------................... .. 159,160

(Incceramus) euvierii........... 152, 158; pis. 18,19

dunveganensis.......... 152,156, / 59; pis. 15-21

labiatus-............................. 153,158,161

lamarcki...--...-...........-..----...-..--. 158

lingua...................................... 161

lobatits-.................................. 161,162

hmdbreckensis..--.................... 161; pi. 22

mcccnnelli- ..................... 159,160; pi. 16

(Mytiloides) labiatus........ 152,156, 160; pis. 19,20

nahwisi................ 159, 160; pis. 15, 18, 19, 21

goodrichensis............... 159,160; pis. 19,22

moberliensis.................... 159,160; pi. 21

patootensis ..___----------- ------ 162

pontoni...........................-.---..-.. 153

(Sphenoceramus) patootensis................ 152,

153,156, 161; pis. 21-23 

steenstrupi---....__-.__ 153,186,169, pis. 19,23

sfeenstrupi............................ 152,153,156

tuberculatut .----. -.- 153,162

(Inoceramus') cuvierii, Incceramus............... 152,

158; pis. 18,19 

dunveganensis, Inoceramus-................. 152,

156, / 69; pis. 15-21

Killik River area..---.-.-_.-------_--------.- 156,157

Kotaneelee formation, fossil content......... 153

Kukpowruk formation, of Sable..._..--...-.. 150 

Kuskokwim region.........._.__......... 160

Kutchik River area-.-.-.-._---------__--._. 157

labiatus, Inoceramus...................... 153,158,161

Inoceramus (Mytiloides)-... 152,156, 160; pis. 19, 20 

Ostracites................................... 160

lamarcki, Inoceramus........................... 158

lata, Terebratulina-........................... 158,160

lingua, Inoceramus---........................... 161

lobatus, Inoceramus.--........................ 161,162

lundbreckensis, Inoceramus-................ 161; pi. 22

Maybe Creek area__..._....._. _-.._- 156,157

mcconnelli, Inoceramus................. 159,160; pi. 16

Megafauna, Lower Cretaceous_._-----_... 150

Micraster coranguinum.......................... 158

Microfauna, Lower Cretaceous.-.- - ------ 150

moberliensis, Inoceramus nahwisi. ----.------.- 159,

160; pi. 21 

Mowry shale, fossil content._----------------- 160

(Mytiloides) labiatus, Inoceramus..-.---------.-- 152,

156, 160; pis. 19, 20

Nanushuk group, defined.-_.-_.--__------_ 150

Nanushuk River area.-.-..------.------------- 157

Naval Petroleum Reserve No. 4_-_------------- 149

nahwisi goodrichensis, Inoceramus............... 159,

160; pis. 19, 21 

Inoceramus-..... .__... 159,160; pis. 15,18,19,21

moberliensis, Inoceramus...-....--- 159,160; pi. 21

Posidonomya.-----,--------- --- - .- 159

Neogastroplius, occurrence.----------------,---- 160

Ninuluk Creek area_-_.............._-------- 156

Ninuluk formation, fossil content..--- 152,156-157,160 

stratigraphic relations.......... _____ 150,152

Page 

Niobrara formation, stratigraphic relations..... 153

Okpikruak formation, stratigraphic relations 150

Ostracites labiatus...---...--...... .- 160

Oumalik formation, stratigraphic relations.__ 150

Outpost Mountain area_--_-----.----- --... 158

patootensis, Inoceramus......................... 162

Inoceramus (Sphenoceramus)....-........... 152,

153,156, 161; p?S. 21-23

Pierre shale, stratigraphic relations.-- 153

pontoni, Inoceramus............................ 153

Posidonomya nahwisi........................... 159

Prince Creek formation, Kogosukruk tongue... 152

stratigraphic relations.-------- - ------ 152

Tuluvak tongue.------- -- --- -...- 152

guadratus, Actinocamax....................... 161,162

Rhynchonella cuvierii............................ 160

Sagavanirktok formation, stratigraphic relitions-.--- . - -- -- 152

Scaphites corvensis.....................--------- 153

hippocrepis.-...........---- -.-..... 162

occurrence.------- ---- --------- 149 152,162

ventricosus.------.----------- ------------ 153

Schrader Bluff formation, Barrow Trail member..-- ---------- 152,153,157-158,162

fossil content.... -.----------- 157,158,162

Rogers Creek member.-- ------- 152,153

Sentinel Hill member--..---------------. 152,153

stratigraphic relations-.. ------ 152,153

Seabee format ion, Ayiyak member.-- .... 150, 

152,153,157,158, 159

fossil content...- .. ----- 152,157.158,161 

stratigraphic relations.--- ---- 150,152,153,158 

unnamed member .. 150,153,157,159,161

September Creek area-... . . - 157

(Sphenoceramus) patootensis, Inoceramus.-...... 152,

153,156,161; pis. 21-23 

steenstrupi, Inoceramus.-... 153,156,162; pis. 19,23

steenstrupi, Inoceramus................... 152.153,156

Inoceramus (Sphenoceramus)..... - - 153,

156, 169; pis. 19, 23

Stratigraphic terminology.. - ... 150

Telegraph Creek formation, fossil content. ------ 162

stratigraphic relations-- - - --------- 153

Terebratulinalata . -.-- -- ------- 158,160

Thomasites, occurrence.-....... 161

Topagoruk formation, stratigraphic relations... 150 

tuberculatus, Inoceramus-.-........ ......... 153,162

Tuku formation, stratigraphic relations..------- 150

Tuluga River area. ----- -------- ... 157

Umiat Mountain area.... ... . - 157 

Utukok-Corwinarea__-_-- - - ----- 150

Vascoceras, occurrence.-...... ------- . 161

ventricosus, Scaphites.--...------------------..-. 153

Watinoceras coloradoense.........-...----------- 153

occurrence. . - ... -- 152,153 

Weasel Creek area. - --------- -.., 156

Wolverine Creek area_--_ __- .- - 156 

woollgari, Collingnoniceras.... ......----- ---- 152

165

o
PLATE 15

[All figures natural size]

FIGURES 1-13. Inoceramus (I noceramus) dunveganensis McLearn (p. 159)

1. Right valve, plesiotype USNM 129217. From USGS Mesozoic loc. 24268.

2. Left valve, plesiotype USNM 129218. From USGS Mesozoic loc. 24268.

3. Left valve, /. athabaskensis McLearn, plastoplesiotype, CGS 9811; McLearn, 1945, Paper 45-27, plate 2, 

figure 10. From Dunvegan formation, Monkman Pass, British Columbia.

4. Left valve, plesiotype USNM 129219. From USGS Mesozoic loc. 20475.

5-7. Left, right, and posterior views, plesiotype USNM 129220. From USGS Mesozoic loc. 24630. 

8-10. Right, anterior, and left views, plesiotype USNM 129221. From USGS Mesozoic loc. 24630.

11. Right valve (?), /. nahwisi McLearn, 1944, Paper 44-17, plate 9, figure 1, CGS 9705. From Shaftebury 

formation, east of Cache Creek, Peace River, Alberta.

12. Left valve, /. dunoeganensis McLearn, plastoplesiotype, CGS unfigured specimen. From Dunvegan formation, Peace River, opposite mouth of Spirit River, Alberta.

13. Left valve, plesiotype USNM 129222. From USGS Mesozoic loc. 20465.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 334 PLATE 15

INOCERAMUS (INOCERAMUS) DUNVEGANENSIS MCLEARN
[All figures natural size except as indicated on plate]

FIGURES 1-5. Inoceramus (Inoceramus) dunveganensis McLearn (p. 159)

1. Right valve, /. mcconnelli Warren, plastocotype, Univ. Alberta CT. 417. From Dunvegan formation north 

bank Peace River, sec. 3, T. 80, R. 3, Alberta.

2. Right valve, /. athabaskensis McLearn, plastoholotype, CGS 8937. From La Biche shale, Athabaska River, 

about 1% miles below Stony Rapids, Alberta.

3. Right valve, plesiotype USNM 129210. From Colville River region, locality unknown.

4. Left valve, I. mcconnelli Warren, plastocotype, Univ. Alberta CT. 418, localtiy as in figure 1.

5. Right valve, plesiotype USNM 129213. From USGS Mesozoic loc. 20475.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 334 PLATE 16

INOCERAMUS (INOCERAMUS) DUNVEGANENSIS MCLEARN
PLATE 17

[All figures natural size except as indicated on plate]

FIGURES 1-5. Inoceramus (Inoceramus) dunveganensis McLearn (p. 159)

1. Right valve, /. athabaskensis McLearn, plastoparatype, COS 8938; McLearn, 1945, Paper 45-27, plate 6, 

figure 1. From La Biche shale, west bank of Athabaska River, just above Stony Rapids, Alberta.

2. Right valve, plesiotype USNM 129223. From USGS Mesozoic loc. 25140.

3. Right valve, plesiotype USNM 129224. From USGS Mesozoic loc. 24271.

4. Left valve, plesiotype USNM 129225. From USGS Mesozoic loc. 20467.

5. Right valve, /. dunveganensis McLearn, plastoholotype, CGS 6106; McLearn, 1945. Paper 45-27, plate 4, 

figure 1. From Dun vegan formation, north bank of Peace River, about 6 miles west of mouth of Riviere 

du Brule, British Columbia.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 334 PLATE 17

INOCERAMUS (INOCERAMUS) DUNVEGANENSIS MCLEARN
PLATE 18

[All figures natural size]

FIGURES 1, 2, 4. Inoceramus (Inoceramus) dunveganensis McLearn (p. 159)

1. Right valve, /. dunveganensis McLearn, unnamed variety, plastohypotype, CGS 9816; McLearn, 1945, 

Paper 45-27, plate 4, figure 2.

2. Right valve, plesiotype USNM 129214. From USGS Mesozoic loc. 24271.

4. Right valve (?), Inoceramus nahiwsi McLearn, plastoholotype, CGS 6344; McLearn, 1944, Paper 44-17,

plate 10, figure 1. From Shaftsbury formation, Peace River, British Columbia. 

3. Inoceramus aff. /. (Inoceramus) cuvierii Sowerby (p. 158)

Right valve of specimen, USNM 129226. From USGS Mesozoic loc. 26533.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 334 PLATE 18

INOCERAMUS (INOCERAMUS) DUNVEGANENSIS MCLEARN AND 

INOCERAMUS AFF. /. (INOCERAMUS) CUVIERII SOWERBY
PLATE 19

[All specimens natural size]

FIGURES 1, 5. Inoceramus aff. I. (Inoceramus) cuvierii Sowerby (p. 158)

1. Right valve of specimen, USNM 129227. From USGS Mesozoic loc. 20413. 

5. Left valve of specimen, US^M 129228. From USGS Mesozoic loc. 24632. 

2, 4. Inoceramus (Inoceramus) dunveganensis McLearn (p. 159)

2. Right valve, Inoceramus nahwisi McLearn, var. goodrichensis McLearn, plastoplesiotype CGS 9713; McLearn 

1944, Paper. 44-17, plate 11, figure 4. From first sandstone of the Sikanni formation, Cypress and Halfway, 

British Columbia. 

4. Left valve (?), Inoceramus athabaskensis McLearn, plastohypotype, CGS 9817; McLearn, 1945, Paper 45-27,

plate 5, figure 1. From Dunvegan formation, locality unknown. 

3. Inoceramus (Mytiloides) labiatus (Schlotheim), (p. 160)

Right valve, plesiotype USNM 129229. From USGS Mesozoic loc. 24641. 

6. Inoceramus (Sphenoceramus) steenstrupi de Loriol (p. 162)

Left valve, plesiotype USNM 129239. From USGS Mesozoic loc. 20481.
GEOLOGICAL SURVEY PKOFESSIONAL PAPER 334 PLATE 19

INOCERAMUS AFF. /. (INOCERAMUS) CUVIERII SOWERBY, INOCERAMUS (INOCERAMUS) 

DUNVEGANENSIS MCLEARN, INOCERAMUS (MYTILOIDES) LABIATUS (SCHLOTHEIM), 

AND INOCERAMUS (SPHENOCERAMUS) STEENSTRUPI DE LORIOL
PLATE 20

[All figures natural size]

FIGURES 1, 4, 5. Inoceramus (Mytiloides) labiatus (Schlotheim) (p. 160)

1. Right valve, plesiotype USNM 129230. From USGS Mesozoic loc. 26545.

4. Right valve, plesiotype USNM 129231. From USGS Mesozoic loc. 20420.

5. Right valve, plesiotype USNM 129232. From USGS Mesozoic loc. 24641. 

2, 3, 6. Inoceramus (Inoceramus) dunveganensis McLearn (p. 158)

2. Right valve, plesiotype USNM 129215. From USGS Mesozoic loc. 24283.

3. Right valve, Inoceramus dunveganensis McLearn, plastoplesiotype, CGS 9813; McLearn, 1945, Paper 45-27,

plate 2, figure 2. From Dunvegan formation, British Columbia. 

6. Left valve, plesiotype USNM 129216. From USGS Mesozoic loc. 24630.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 334 PLATE 20

INOCERAMUS (MYTILOIDES) LABIATUS (SCHLOTHEIM) AND INOCERAMUS 

(INOCERAMUS) DUNVEGANENSIS MCLEARN
PLATE 21

[All figures natural size]

FIGURES 1-4, 6. Inoceramus (Inoceramus) dunveganensis McLearn (p. 158)

1. Left valve, plesiotype USNM 129211. From USGS Mesozoic loc. 20468.

2. Right valve, plesiotype USNM 129212. From USGS Mesozoic loc. 20476.

3. Left valve, Inoceramus nahwisi moberliensis McLearn, plastoholotype CGS 8945; McLearn, 1944, Paper 

44-17, plate 10, figure 7. From the Goodrich formation, Cool Creek, south of Peace River Canyon, 

British Columbia.

4. Left valve, Inoceramus nahwisi moberliensis McLearn; unfigured plastoparatype CGS 8945; location as above. 

6. Right valve, Inoceramus nahwisi McLearn goodrichensis McLearn, plastoplesiotype CGS 9710; McLearn,

1944, Paper 44-17, plate 2, figure 5. From Sikanni formation, talus in creek, Sikanni Chief River, 3 miles

east of highway bridge. 

5. Inoceramus (Sphenoceramus) patootensis de Loriol (p. 161)

Left valve, plesiotype USNM 129235. From USGS Mesozoic loc. 26498.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 834 PLATE 21

INOCERAMUS (INOCERAMUS) DUNVEGANENSIS MCLEARN AND 

INOCERAMUS (SPHENOCERAMUS) PATOOTENSIS DE LORIOL
PLATE 22

[All figures natural size except as noted on plate]

FIGURES 1-3. Inoceramus (Sphenoceramus) patootensis de Loriol (p. 161)

1. Rubber cast of right valve, plesiotype USNM 129233. From USGS Mesozoic loc. 26509.

2. Right valve, Inoceramus lundbreckensis McLearn, plastoholotype, Natl. Mus. Canada 9037. From Alberta 

shale, 50 feet from top, Crowsnest River, Alberta.

3. Right valve, plesiotype USNM 129234. From USGS Mesozoic loc. 26509.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 834 PLATE 22

X3/4

INOCERAMUS (SPHENOCERAMUS) PATOOTENSIS DE LORIOL
PLATE 23

[All figures natural size]

FIGURES 1, 2. Inoceramus (Sphenoceramus) steenstrupi de Loriol (p. 162)

1. Fragment, valve unknown, plesiotype USNM 129238. From USGS Mesozoic loc. 26504.

2. Right valve (?), plesiotype USNM 129237. From USGS Mesozoic loc. 20493. 

3. Inoceramus (Sphenoceramus) patootensis de Loriol

Right valve, plesiotype USNM 129236. From USGS Mesozoic loc. 20461.
GEOLOGICAL SUEVEY PROFESSIONAL PAPER 334 PLATE 23

INOCERAMUS (SPHENOCERAMUS) STEENSTRUPI DE LORIOL AND 

INOCERAMUS (SPHENOCERAMUS) PATOOTENSIS DE LORIOL

U.S. GOVERNMENT PRINTING OFFICE: I960 O - 527586