Jurassic Paleobiogeography 

of Alaska

GEOLOGICAL SURVEY PROFESSIONAL PAPER 801
Jurassic Paleobiogeography 

of Alaska

By RALPH W. IMLAY and ROBERT L. DETTERMAN

GEOLOGICAL SURVEY PROFESSIONAL PAPER 801

Changes in the paleogeography of Alaska during 

Jurassic time are revealed by the distribution, 

succession, and differentiation of molluscan 

faunas and by the characteristics of the 

associated sedimentary rocks

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1973
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 73-600141

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

Washington, D.C. 20402 - Price 65 cents domestic postpaid or 45 cents GPO Bookstore

Stock Number 2401-00347
CONTENTS

Page

Abstract _ __ 1

Introduction 1

Acknowledgments ________________ 2

Distribution of Jurassic rocks ____ ___________ 2

Comparisons of stratigraphic and lithologic features_ 8

Southern Alaska ___________________ 8

Northern Alaska ___________________ 9

Occurrences of Jurassic unconformities ________ 14

Southern Alaska ___________________ 14

Northern Alaska ____________________ 16

Extent of Jurassic seas _________________ 16

Succession and differentiation of ammonites _____ 20

Page

Fossil occurrences by stages 21

Hettangian 21

Sinemurian __ 22

Pliensbachian 22

Toarcian ______ _ 23

Bajocian ______ 23

Bathonian ________ 24

Callovian ____________-___ 24

Early Oxfordian _________-____________ 25

Late Oxfordian to early Kimmeridgian _ 25

Late Kimmeridgian to early middle Tithonian 26

Late middle to late Tithonian ______ _ 27

References ______ _ 28

Index _____________________________ 33

ILLUSTRATIONS

FIGURES 1-9. Maps showing distribution of Jurassic fossils in Alaska:

1. All stages of the Jurassic ______ _____________.

2. Hettangian and Sinemurian ______ - __________ __ ___.

3. Pliensbachian and Toarcian ____-_ - - ______ __ _.

4. Bajocian ___________________ ______ _____ ______.

5. Bathonian and Callovian ___________ ________________

6. Early Oxfordian ______________________________.

7. Late Oxfordian to early Kimmeridgian _ _____.

8. Late Kimmeridgian to early middle Tithonian __________.

9. Late middle to late Tithonian ____ ________________.

10. Index map of Jurassic areas in Alaska _____________________

11. Correlation charts of Jurassic rocks in Alaska-_ ____________________

12-15. Chart showing 

12. Occurrences of unconformities in the Jurassic of Alaska _ _.

13. Correlation of Hettangian to Toarcian ammonite faunas in Alaska .

14. Correlation of Bajocian to Callovian ammonite faunas in Alaska

15. Correlation of Oxfordian to Tithonian molluscan faunas in Alaska

Page

2

3

3

4

4

5

5

6

6

7

10

15

17

18

19

ill
JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

By RALPH W. IMLAY and ROBERT L. DETTERMAN

ABSTRACT

Jurassic marginal seas occupied considerable areas in 

southern and northern Alaska and in the western part of the 

Kuskokwim region of southwestern Alaska. They appear to 

have been absent during late Callovian time, much restricted 

during Hettangian, Bathonian, early Oxfordian and late 

Tithonian time, and most extensive during Sinemurian, 

Bajocian, and late Oxfordian to middle Tithonian time. A 

large area in central Alaska was probably never covered. 

A southwestern prolongation of that area from the Talkeetna 

Mountains westward to the western end of the Alaska Peninsula was the site of granitic intrusions during late Early 

Jurassic time and of extensive erosion during Middle and 

Late Jurassic time. Variations in the rate of uplift of the 

area of these granitic intrusive rocks may explain why 

marine transgressions and regressions were at different times 

in southern than in northern Alaska during the Bajocian 

and Bathonian. Connection of the northern and southern 

marginal seas occurred through Yukon Territory and easternmost Alaska.

The Jurassic ammonite succession in Alaska is similar 

to that in central and northern Europe and northern Asia. 

In Lower Jurassic beds, it is essentially identical. In Bajocian 

and in Oxfordian to lower Kimmeridgian beds, the ammonite 

succession in Alaska differs from that in the other areas 

mainly by the presence of some genera found only in areas 

bordering the Pacific Ocean and by the absence of a few 

genera common in central and northern Europe. In contrast, the Bathonian rocks of Alaska contain ammonites, 

such as Arcticoceras, Arctocephalites, and Cranocephalites, 

that are widespread in the Arctic region but are unknown 

in central Europe. Comparisons with the Tithonian of Europe 

are not possible because ammonites of that age, other than 

Lytoceras and Phylloceras, are not yet known from Alaska. 

The Alaskan Jurassic ammonites of late Pliensbachian Age 

and of Bathonian to early Kimmeridgian Age belong mostly 

to the Boreal realm and have very little in common with 

Tethyan realm ammonites such as those found in areas 

bordering the Mediterranean Sea.

INTRODUCTION

This report deals in a broad way with changes in 

geography, stratigraphy, and ammonite assemblages 

in Alaska during Jurassic time. It is based on data 

of which at least half has been obtained during the 

last 25 years; it presents maps depicting the approximate positions and distribution of megafossil

occurrences of the various stages; and it describes 

those fossil occurrences or refers to publications in 

which they have been described. In addition, the 

report summarizes existing knowledge concerning 

gross stratigraphic and lithologic features, position 

and duration of unconformities, extent and changes 

in marginal Jurassic seas, succession and differentiation of ammonite faunas, comparisons with ammonite successions elsewhere, and possible relationship of ammonite differentiation to major events 

in the Gulf of Mexico and in the Atlantic Ocean.

The paleogeographic maps presented herein for 

the stages of the Jurassic are intended primarily to 

show the main areas of marine deposition and the 

provenance of the sediments; at the same time it is 

recognized that the areas probably are not in their 

true palinspastic position. Considerable evidence has 

been collected in recent years for large-scale transcurrent fault movements of regional proportions. 

Many of the Jurassic localities in southern Alaska 

certainly were involved in major dislocations bordering the rim of the north Pacific Ocean (Brew and 

others, 1966; Grantz, 1966; Richter and Jones, 1970; 

and St. Amand, 1957). Some dislocation of Jurassic 

strata occurred also in northern Alaska (Brosge 

and Tailleur, 1970; Tailleur and Brosge, 1970), but 

the dislocations were not as severe as in southern 

Alaska. The authors hope that locality and stratigraphic data published herein will stimulate field 

geologists to obtain more data on individual basins 

so that more accurate paleogeographic maps can be 

drawn.

Most of the geographic features, areas, and towns 

mentioned herein are shown on a physiographic map 

of Alaska prepared by Wahrhaftig (1965, pi. 1). 

Many of the creeks mentioned under locality descriptions dealing with northern Alaska are shown on an 

index map prepared by Imlay (1955, p. 79). Other 

streams mentioned under locality descriptions are 

shown on maps published by the authors listed in 

the locality descriptions at the end of this report.
JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

ACKNOWLEDGMENTS

For the data published herein, the writers are 

greatly indebted to many geologists of the major 

oil companies and the U.S. Geological Survey and to 

a few individuals such as prospectors and mountain 

climbers. Especial thanks for their aid in reading 

the manuscript, in checking or rewriting the fossil 

locality data, or for contributing valuable collections 

are given to consulting geologist M. D. Mangus, to 

George Gryc, Arthur Grantz, J. M. Hoare, D. L. 

Jones, A. S. Keller, E. M. MacKevett, G. W. Moore, 

W. W. Patton, Jr., H. N. Reiser, Donald Richter, and 

E. G. Sable of the Geological Survey, and N. J. Silberling of Stanford University, The major oil companies whose geologists in recent years have furnished valuable fossil collections and locality data 

include the BP Alaska Inc., the Standard Oil Company of California, and the Atlantic Richfield Oil 

Company.

DISTRIBUTION OF JURASSIC ROCKS

Marine Jurassic fossils have been found in Alaska 

mostly in its northern, southern, and southwestern 

parts (fig. 1). The overall distribution of the fossils 

by stages is shown in figures 2-9. Most of the localities indicated therein represent single fossil collections, but some represent two or more collections 

from a sequence of beds in a small area, or many 

collections from an area of appreciable size, such as

the Iniskin Peninsula or the Talkeetna Mountains 

(fig. 10; also see Wahrhaftig, 1965, pi. 1).

Marine Jurassic fossils have not been found in a 

large area in central Alaska, nor in a southwestern 

prolongation (fig. 1) that trends southwest near 

and parallel to the Alaska Range. Most of the 

boundaries of this area are approximations that 

probably will be altered by future geologic mapping. 

The southern boundary, however, from the Talkeetna Mountains westward and southwestward to 

the Alaska Peninsula is well defined by intermittent 

occurrences of granitic rocks that were intruded 

during Early Jurassic time and that shed much 

coarse debris southward during Middle and Late 

Jurassic time (Grantz and others, 1963; Detterman 

and others, 1965; Detterman and Hartsock, 1966, 

p. 64, 70, 71; Burk, 1965, p. 73, 75-77).

The apparent absence of any marine Jurassic 

throughout the southern part of central Alaska 

north of Cook Inlet may be ascribed to erosion during Middle and Late Jurassic time. The lack of 

Jurassic fossils throughout the rest of central 

Alaska may have a similar explanation, but may be 

due to nondeposition. Their absence cannot be explained by post-Jurassic erosion, because at many 

places, marine Triassic rocks are overlain directly 

by lowermost Cretaceous marine rocks. Overall, the 

evidence favors the presence of a landmass in central Alaska during Jurassic time.

122' 114'

FIGURE 1. Distribution of Jurassic fossils of all stages in Alaska.
DISTRIBUTION OF JURASSIC ROCKS

FIGURE 2. Distribution of Hettangian and Sinemurian fossils and inferred seas in 

Alaska. Land areas ruled. X, Hettangian and Sinemurian; H, Hettangian only; S, 

Sinemurian only. Numbers keyed to descriptions of Hettangian and Sinemurian fossil occurrences.

FIGURE 3. Distribution of Pliensbachian and Toarcian fossils and inferred seas in Alaska. 

Land areas ruled. X, Pliensbachian and Toarcian; P, Pliensbachian only; T, Toarcian 

only. Numbers keyed to descriptions of Pliensbachian and Toarcian fossil occurrences.
JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

122' 114°

FIGURE 4. Distribution of Bajocian fossils and inferred seas in Alaska. Land areas ruled. 

Numbers keyed to description of Bajocian fossil occurrences.

162° 154- 146' 138° ISO- 122' 114°

FIGURE 5. Distribution of Bathonian and Callovian fossils and inferred seas in Alaska. Land 

areas ruled. X, Bathonian and Callovian; B, Bathonian only; C, Callovian only. Numbers keyed to descriptions of Bathonian and Callovian fossil occurrences.
DISTRIBUTION OF JURASSIC ROCKS

146 - 138°

FIGURE 6. Distribution of early Oxfordian fossils and inferred seas in Alaska. Land areas 

ruled. Numbers keyed to descriptions of early Oxfordian fossil occurrences.

FIGURE 7. Distribution of late Oxfordian to early Kimmeridgian fossils and seas in Alaska. 

Land areas ruled. Numbers keyed to descriptions of late Oxfordian to early Kimmeridgian fossil occurrences.
JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

178° 170' 162' 138' 130' 122- 114°

FIGURE 8. Distribution of late Kimmeridgian to early middle Tithonian fossils and inferred 

seas in Alaska. Land areas ruled. Numbers keyed to descriptions of late Kimmeridgian 

to early middle Tithonian fossil occurrences.

146' 138"

FIGURE 9. Distribution of late middle to late Tithonian fossils and inferred seas in Alaska. 

Land areas ruled. Numbers keyed to descriptions of late middle to late Tithonian fossil occurrences.
DISTRIBUTION OF JURASSIC ROCKS

I
8 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

COMPARISONS OF STRATIGRAPHIC AND 

LITHOLOGIC FEATURES

Jurassic rocks in Alaska have been studied in 

greatest detail in the southern and northern parts 

of the State. Consequently, critical stratigraphic and 

fossil control is available for more areas within 

those parts than elsewhere, as is reflected in the correlation charts (fig. 11). Igneous rocks that are 

radiometrically dated (Detterman and others, 1965; 

Grantz and others, 1963, 1966; Reed and Lanphere, 

1969; Reiser and others, 1965) are present in some 

of the same areas and confirm ages established by 

paleontology.

Stratigraphic analysis of Jurassic rocks in some 

areas of Alaska indicate that strata now in close 

proximity were originally deposited under different 

conditions and from different source areas. These 

rocks are generally near known faults of demonstrably large displacement, and the original site of deposition can be inferred with some degree of accuracy. 

The movement of these rocks to their present localities may result from plate tectonics initiated by 

continental drift, as suggested by many authors 

(Carey, 1958; Hamilton, 1968; Tailleur and Brosge, 

1970; Richter and Jones, 1970; Rickwood, 1970). 

This report is not primarily concerned with plate 

tectonics, but some palinspatic interpretations are 

pertinent to the discussion of the stratigraphy.

SOUTHERN ALASKA

In southern Alaska, Jurassic strata are exposed 

in a nearly continuous arcuate belt from the extreme 

southeastern part near Ketchikan to near the tip 

of the Alaska Peninsula (figs. 10 and 11A). Lower 

Jurassic rocks, however, are known only from the 

central part of this belt between Juneau on the east 

and Wide Bay on the west (Burk, 1965; Detterman 

and Hartsock, 1966; Detterman and Reed, 1964; 

Grantz, 1960a,b, 1961a,b; Imlay, 1952; Juhle, 1955; 

Kirschner and Minard, 1949; MacKevett, 1963, 

1065a,b, 1969, 1970a,b; Martin, 1905, 1926; Martin 

and Katz, 1912; MoflStt, 1922a,b, 1927; Paige and 

Knopf, 1907; Smith, 1917, 1939; Stanton and Martin, 1905).

During Early Jurassic time, deposition occurred 

within a nearly continuous belt, at least part of 

which bordered a volcanic island-arc system. Volcanic and volcaniclastic rocks form most of the record from the Katmai area in the south (Mather, 

1925; Keller and Reiser, 1959) to the Talkeetna 

Mountains in the north (Grantz, 1960a,b, 1961a,b), 

but the main eruptive centers were in the Cook Inlet 

area (Detterman and Hartsock, 1966). At the same

time, argillite, limestone, chert, spiculite, and shale 

were deposited both as beds within the volcanic 

rocks, and at a considerable distance from the islandarc system in areas now represented by the Kuskokwim region (Cady and others, 1955; Hoare, 1961; 

Hoare and Coonrad, 1961a,b) and the Wrangell 

Mountains (MacKevett, 1963, 1965a,b, 1969, 

1970a,b). Near the end of the subperiod, the rocks 

of southern Alaska were highly deformed and intrude'd by granitic batholiths in the Talkeetna Mountains (Grantz and others, 1963) and in the Cook 

Inlet area (Detterman and others, 1965; Reed and 

Lanphere, 1969). These granitic rocks are dated at 

155 to 175 m.y. The oldest date probably represents 

the beginning of plutonism and may correspond to 

an unconformity dated paleontologically as late 

Toarcian to early Bajocian. Small mafic intrusive 

bodies are associated with the Lower Jurassic volcanic rocks in the Cook Inlet area and predate the 

granitic plutons.

Middle Jurassic rocks in southern Alaska are 

mainly graywacke-type sandstone, polymictic conglomerate, siltstone, and shale suggestive of rapid 

deposition in a subsiding epieugeosynclinal trough. 

Volcanic rocks are a major part of the sequence 

only in the Kuskokwim region (Cady and others, 

1955; Hoare, 1961). In general, the characteristics 

of the rocks in southern Alaska indicate a considerable change in depositional environment between 

Early and Middle Jurassic time. This change probably reflects erogenic activity that resulted in plutonism near the boundary of the subperiods. Similar 

erogenic activity continued throughout Middle Jurassic time, as indicated by the shifting positions 

of the seas and the uplift and erosion of the bordering uplands to the west and northwest. The many 

polymictic conglomerates in the Middle Jurassic sequence that contain clasts of both the granitic plutons and the Lower Jurassic volcanic rocks, which 

were mainly of marine origin, are evidence of these 

events. However, the presence of laumontite in the 

rocks of the Cook Inlet area suggests derivation 

from active volcanoes in the Kuskokwim region and 

indicates, therefore, that the relative geographic 

position of the two regions has not greatly changed 

since Middle Jurassic time.

During most of Late Jurassic time, marine deposition in southern Alaska took place in two or more 

basins that fragmented from an earlier larger Jurassic basin after a period of general emergence at 

about the transition from Callovian to Oxfordian 

time. One basin occupied the site of the Alaska 

Peninsula-Cook Inlet region and continued as far
STRATIGRAPHIC AND LITHOLOGIC FEATURES

east as the Wrangell Mountains; it was filled mainly 

with arkosic sediments derived from nearby granitic batholiths to the west and north (Atwood, 

1911; Burk, 1965; Capps, 1923, 1934; Detterman 

and Hartsock, 1966; Grantz and others, 1966; Keller 

and Reiser, 1959; Kellum, 1945; Kirschner and Minard, 1949; Kirschner and Lyon, 1973; MacKevett, 

1963, 1965a,b, 1969, 1970a,b, 1971; Martin, 1905, 

1921, 1925, 1926; Martin and Katz, 1912; Mather, 

1925; Miller and others, 1959; Moffit, 1922a,b, 1927, 

1938a, 1943, 1954; Paige, 1906; Smith, 1925; Smith 

and Baker, 1924; Spurr, 1900; Stanton and Martin, 

1905; Stone, 1905). Some silt and clay were deposited as beds within the arkosic sediments throughout most of the basin and locally formed a considerable part of the section. Deposition was continuous to the end of the Jurassic only at the extreme 

southern end of the Alaska Peninsula; elsewhere, 

the uppermost Jurassic beds were removed or deposition did not occur.

Another basin, or basins, existed in easternmost 

Alaska and probably extended into adjoining British 

Columbia, as shown by the presence of thousands of 

feet of Upper Jurassic graywacke, mudstone, conglomerate, argillite, and slate now exposed in southeastern Alaska (Brew and others, 1966; Lathram 

and others, 1960; Loney, 1964; Martin, 1926) and 

in the eastern Alaska Range (Richter, 1971). The 

characteristics of these rocks contrast so much with 

those of the arkosic rocks deposited at the same 

time in the Cook Inlet region that the provenance of 

deposition and the lithology of the source areas must 

have been quite different. The differences could be 

explained by extensive crustal movements, as postulated by Richter and Jones (1970). These crustal 

movements have apparently foreshortened the distance between the basins by many tens of miles along 

major faults in southeastern Alaska.

NORTHERN ALASKA

Jurassic rocks in northern Alaska have been 

studied in detail only in the eastern part (figs. 10 

and 115). Characteristics of the strata indicate that 

the provenance of deposition and lithology of the 

source areas were considerably different than in 

southern Alaska during most of the Jurassic 

(Brosge and Tailleur, 1970; Detterman, 1973; Gryc 

and Lathram, 1954; Gryc and Mangus, 1954; Keller 

and others, 1961; Leffingwell, 1919; Reed, 1968; 

Reiser and Tailleur, 1969; Reiser and others, 1970; 

Sable, 1965; Smith and Mertie, 1930). However, 

marine connections with southern Alaska probably 

existed via Yukon Territory and east-central Alaska 

(Frebold and others, 1967; Jeletzky, 1962). The

stratigraphic sequence in the western part of northern Alaska is complicated by thrust faulting, which 

has juxtaposed two dissimilar Jurassic sections; one 

is typical of northern Alaska sedimentary rocks, 

and the other is more closely related to Jurassic 

volcanic rocks south of the Brooks Range (Brosge 

and Tailleur, 1970; Detterman, 1972; Gates and 

Gryc, 1963; Jones and Grantz, 1964; Lathram, 1965; 

Patton and Grantz, 1962; Tailleur, 1969).

Lower Jurassic rocks in northern Alaska are 

mainly fissile clay shale and claystone that commonly 

contain limestone concretions. Siltstone and silty 

shale are abundant locally. Chert, tuff, graywacke, 

and oil shale are present at a few localities in the 

western part (Brosge and Tailleur, 1970; Detterman, 1973; Imlay, 1955, 1967; Mangus and others, 

1954; Tailleur, 1964; Tailleur and Kent, 1954; Tailleur and others, 1966). A glauconitic sandstone is 

present in the subsurface along the north coast 

(Bergquist, 1966; Collins, 1958, 1961; Detterman, 

1973; Gates and others, 1968; Imlay, 1955; Loeblich, 

1954; Payne, 1955; Payne and others, 1951; Robinson, 1959), and a massive sandstone of earliest 

Jurassic or latest Triassic age is present along the 

north flank of the Brooks Range in northeastern 

Alaska (Detterman, 1973) ; Sable, 1965). The sandstones would indicate that sediment sources were 

both north and south. The Lower Jurassic section 

is not complete at any locality and is only sparsely 

fossiliferous; consequently, regional unconformities 

are impossible to determine. There are probably 

many local unconformities, and paleontologic evidence suggests that parts of the Hettangian, Sinemurian, and Pliensbachian are missing.

Siltstone, silty shale, and pyritic clay shale are 

the main rock types present in the Middle Jurassic 

of northern Alaska. Orange-weathering clay ironstone concretions and beds are also common. Graywacke and tuff are present locally in the central 

part (Chapman and others, 1964; Jones and Grantz, 

1964; Patton and Keller, 1954; Patton and Tailleur, 

1954, 1964). The only good exposures for this part 

of the Jurassic are in northeastern Alaska (Brosge 

and Tailleur, 1970; Detterman, 1973; Gryc, 1951; 

Gryc and Mangus, 1954; Keller and others, 1961; 

Leffingwell, 1919; Reiser and Tailleur, 1969; Reiser 

and others, 1970; Sable, 1965; Whittington and 

Sable, 1954), where a major middle Bajocian to 

early Bathonian unconformity can be detected both 

lithologically and paleontologically (Imlay, 1955, 

1970). Elsewhere in northern Alaska, the rocks are 

too poorly exposed to determine the presence of 

unconformities.
10 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

3

Puale BayAlinchak Bay

Iniskin Bay-Tuxedni Bay 

wide Bay-Mother Goose Cook Inlet area

Tertiary

Port MollerChignik Bay

Staniukovich 

Formation 

0-2,000 ft 

Arkosic sandstone 

and siltstone Dark siltstone 

and fine-grained 

sandstone

Dark siltstone 

and fine-grained 

sandstone Naknek

Formation 

3,000-5,000 ft 

Arkosic sandstone, 

siltstone, conglom 

erate, and claystone

PioiniefoyArKoseMembe 

800-3,300 ft 

Arkosic sandstone

Aricosicla"ndstone 

siltstone, and 

conglomerate

Arkosic sandstone, 

siltstone, and 

conglomerate

Snug Harbor Siltstone Member

700-850 ft 

Dark siltstone

Siltstone and minor 

sandstone

Lower sandstone member 

0-850 ft ^

Chisik Conglomerate 

Member 0-560 ft

SheHkof Formation 

Upper shale

900-1,800 ft 

Sandstone and

conglomerate

1,000-4,000 ft 

Lower shale

800-1,800 ft

Shelikof Formation 

Upper shale

900-1,800 ft 

Sandstone and

conglomerate

4,000+ ft

Paveloff Siltstone Member 900-1,370 ft 

Gray siltstone, sandstone beds at base

Tonnie Siltstone Member

820-1,310 ft 

Brown siltstone ?/~^-O

Bowser Formation 

1,280-1,880 ft 

Sandstone, conglomerate 

siltstone, and shale

Cynthia Falls Sandstone

Fitz Creek Siltstone 640-1,280 ft Kialagvik Formation

1,750ft

Sandstone, shale, 

and minor 

conglomerate

ikema Sandstone 500-880

Red Glacier Formation 

1,980-4,540 ft -Hums' Quartz diorite 

160-175 m.y

Quartz diorite 

155-175 m.y.

Upper part 

1,300ft 

Dark shale and 

sandstone, few 

limestone 

concretions

Horn Moflntain

Tuff Member

1,800-2,850 ft 

Tuff, flows, and minor sandstone

Portage Creek

Agglomerate Member 

2,250-2,850 ft 

Agglomerate, flows, breccia, 

and argillite

Talkeetna 

Formation 

5,000+ ft 

Flows, tuff, 

breccia, and 

agglomerate Marsh Creek

Breccia Member 

1,850-3,350 ft 

Breccia, flows, agglomerate 

and minor arprllite

Lower part 

1,000 ft 

Tuffaceous and 

calcareous shale 

sandstone, and 

volcanic breccia

FIGURE 11. A, Correlation of Jurassic rocks in southern Alaska. Vertical lines indicate strata missing; right diagonal lines

ity; jagged lines indicate gradational or indefinite contact. Numbered columns keyed
STRATIGRAPHIC AND LITHOLOGIC FEATURES 11

Kuskokwim area

southwestern

Alaska

Lower Cretaceous

Andesite, tuff, 

siltstone, and 

conglomerate 

Several hundred 

feet

Argillite, limestone, 

siltstone, and 

sandstone 

50-200 ft

Upper Triassic

7

Talkeetna 

Mountains

Lower Cretaceous

Sandstone and 

siltstone

Siltstone and 

shale

Conglomerate

mmnn

Chinitna Formation

850ft

Siltstone and shale, 

minor sandstone 

at base

0-800

Sandstone, sh' i\e 

siltstone, and 

conglomTuxedni Group 

700-1,200 ft

Talkeetna 

Formation 

6,000-8,000 ft

Upper part 

Sandstone and 

argillite

Middle part 

Flows and 

pyroclastics

Lower part 

Argillite and 

sandstone

8

Wrangell 

Mountains

Root Glacier Formation 

0-3,800 ft 

^Mudstone, siltstone, 

graywacke, 

limestone,

and 

conglomerate

Kotsina 

Conglomerate 

2,000-2,500 ft

Nizina Mountain 

Formation 

0-1,500 ft 

Fine-grained 

graywacke

Lubbe Creek 

Formation 

100-200 ft 

Spiculite and 

coquina

McCarthy

Formation 

Upper member

2,000+ ft

Chert, spiculite,

shale, and

limestone

Upper Triassic

Eastern Alaska

RangeNutzotin Mountains

Lower Cretaceous

Graywacke, mudstone, 

and argillite 

5,000-10,000 ft 

in part of Early Cretaceous age >

Argillite, minor siltstone 

and graywacke 1,000 ft

Upper Triassic

10

Admiralty and Gravina

Islands, southeastern

Alaska

Lower Cretaceous

<0 O

55(3

Seymour Canal 

Formation

Lower part 

4,000-8,000 ft

Argillite, slate, 

graywacke, and 

conglomerate

Gravina Island

Formation

2,500+ ft 

Upper member

Grit, conglomerate

and siltstone 

Middle member

Andesite 

Lower member

Graywacke, slate,

and conglomerate

Upper Triassic

Characteristic fossils in 

southern Alaska

Buchia piochii 

B. fischeriana 

.7_________________?.

B. rugosa 

B. mosquensis

Amoeboceras 

(Prionodoceras) 

spiniferum

Dichotomosphinetes

Cardioceras distorts

C. (Scarburgiceras) martini

Cadoceras (Stenocadoceras) 

stenoloboide

Lilloettia buckmani 

Cadoceras catostoma 

Paracadoceras tonniense

Arctocephalites cf. A. elegans

Cranocephalites costidensus

Megasphaeroceras, Leptosphinctes

Chondroceras allani Teloceras itinsae

Papilliceras, Witchellia, Emeleia, £s

Dorsetensia \ Parabigotites

Sonninia, Docidoceras

Tmetpceras, Erycitoides ~~~II-~e--~< ^"\

VX

Grammoceras

Haugia, Phymatoceras

Dactylioceras cf. D. commune

XXXXXXXXXXXXXN

Pleuroceras, Amaltheus

Uptonia, Apoderoceras

Crucilobiceras

Microderoceras

Arnioceras

Coroniceras

Wachneroceras

indicate beds not exposed; left diagonal lines indicate lack of fossil data; wavy lines indicate unconformity or disconformto figure 10. Compiled October 1971. (Figure 11 continued on following pages.)
12 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

Stage Lisburne 

Peninsula

12

De Long 

Mountains

Arctic Slope-Foothills Belt

13

Utukok-Etivluk 

Rivers area

14

Killik-Itkillik 

Rivers area

15

SagavanirktokCanning Rivers area

16

Ignik Valley-Aichilik 

River area

Overlying beds Lower Cretaceous wer Cretaceous

Telavirak Formation

5,000+ ft

Sandstone, siltstone, 

mudstone, and shale 

turbidite

May be in part of 

Early Cretaceous 

age

Ogotoruk 

Formation 

5,000+ft

Mudstone, siltstone, 

and sandstone 

turbidite

Lower Cretaceous ^^/^^^x Lower Cretaceous 

'iglukpuk Formation

(abandoned) 

Several hundred feet 

Graywacke, siltstone 

sjaej_a

Lower Cretaceous Lower Cretaceous

Pyritic clay shale 

and clay ironstone 

concretions 

< 1,000 ft

Tiglukpuk Formation

(abandoned)

1,000± ft

Graywacke, clay shale, 

siltstone, chert, 

and conglomerate

Oxfordian

Callovian

Bathonian

Bajocian

Toarcian

Pliensbachian

Sinemurian

Hettangian

Clay shale and limestone 

concretions (thickness 

included with above)

Kingak Shale 

200-1,800 ft 

Dark pyritic clay 

shale, siltstone, 

clay ironstone 

concretions, and 

minor sandstone

Kingak Shale 100-500 ft 

Clay shale and siltstone

Kingak Shale

0-150 ft 

Pyritic clay shale, "-\

silty shale, siltstone

and clay ironstone

concretions

Kingak Shale 

50-200 ft 

Siltstone and shale

Tiglukpuk Formation

(abandoned) 

Graywacke, siltstone 

shale, and tuff 

200-300 ft

Kingak Shale 

90-400 ft 

Clay shale and 

siltstone

Kingak Shale

300-1,500 ft 

Pyritic clay shale, 

silty shale, siltstone, 

and limestone

Kingak Shale 

50-800 ft

Clay shale, silty shale, 

siltstone, and 

clay ironstone

Underlying beds Upper Triassic Upper Triassic

Chert, shale, 

and oil shale 

30ft

Tuff, shale, 

siltston, 

and graywacke Kingak Shale 50-600 ft 

Fissile clay shale 

7 7 

Kingak Shale 100-500 ft 

Fissile clay shale .

Siliceous clayston 

A few feet 

?_______7

Siliceous clayston 

30ft

Upper Triassic Upper Triassic "Upper Triassic Upper Triassic

FIGURE 11. Continued. B, Correlation of Jurassic rocks in northern and east-central Alaska. Vertical lines indicate strata

unconformity or disconformity; jagged lines indicate gradational or
STRATIGRAPHIC AND LITHOLOGIC FEATURES 13

17

Arctic coastal plains

Barrow-Topagoruk

(subsurface)

Lower Cretaceous

18

Joe CreekBritish Mountains

Lower Cretaceous

East-central Alaska

19

Kandik-Nation 

Rivers area

Lower Cretaceous

20

Porcupine,

Coleen, Sheenjek

Rivers area

Lower Cretaceous

Characteristic fossils in northern and east-central Aaska

Kingak Shale

500+ ft 

Siltstone, silty 

shale, fissile clay 

shale, and clay 

ironstone

Kingak Shale

100-950 ft 

Clay shale, siltstone,

and minor glauconitic

sandstone

Clay shale (included 

with above)

Buchia unvchensis 

B. fischeriana

 7 

B. rugosa

B. mosquensis

Amoeboceras (Prionodoceras)

\X\\\\\\\\\

Cardioceras I Scar b

Basalt, gabbro, 

and quartz diorite 

155-168 m.y.

Pseudocadocerasl, Cadoceras

Arcticoceras Kochi

Arctocaphalites clegans

Cranocephalites

Glenn Shale (in part)

5,000± ft

Carbonaceous shale, 

siltstone, and 

argillite

(includes rocks of 

Early Cretaceous 

to Late Triassic

Arkelloceras

Erycitoides howelli and Tmetoceras

Pseudolioceras maclintocM

Pseudolioceras

Dactylioceras cf. D. commune

D. semicelatum Nodicoeloceras

Amaltheus

Dark sandstone, 

siltstone, shale, 

and quartzite 

1,000± ft

Crucilobiceras

Arietites

Devonian to Triassic Lower to Upper Triassic Upper Triassic N 'Upper~frIassic"

Psttoceras

missing; right diagonal lines indicate beds not exposed; left diagonal lines indicate lack of fossil data; wavy lines indicate 

indefinite contact. Numbered columns keyed to figure 10. Compiled October 1971.
14 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

Upper Jurassic rocks in northern Alaska consist 

mainly of siltstone and shale similar to those of the 

Middle Jurassic. The principal exceptions are a 

thick sequence of sandstone, siltstone, and mudstone 

turbidites exposed in the far western part of northern Alaska near Cape Lisburne (Campbell, 1967; 

Chapman and Sable, 1960; Detterman, 1972; Knowlton, 1914; Sable and Mangus, 1954; Tailleur, 1969) 

and a thin sequence of tuffaceous graywacke, conglomerate, and chert exposed in the central part of 

northern Alaska (Brosge and Tailleur, 1970; Chapman and others, 1964; Patton, 1956; Patton and 

Tailleur, 1964). These rocks that are exceptions 

may have been faulted into their present positions 

from somewhere south of the modern Brooks Range 

(Brosge and Tailleur, 1970; Tailleur, 1969).

Most of northern Alaska was apparently emergent 

during late Callovian and early Oxfordian time and 

again during the late Tithonian. These periods of 

emergence are marked by major unconformities and 

by a change in the faunal assemblages. No ammonites have been found in rocks of Tithonian Age, 

but the pelecypod Buchia is present in many areas 

(Brosge and Tailleur, 1970; Detterman, 1973; Imlay, 1959; Patton, 1956).

A sequence of graywacke, siltstone, shale, chert, 

and conglomerate in the central part of northern 

Alaska was formerly mapped as the Tiglukpuk 

Formation of Late Jurassic age (Patton, 1956). The 

type locality on Tiglukpuk Creek is now known to 

be a faulted section consisting of Middle Jurassic 

and Lower Cretaceous rocks (Jones and Grantz, 

1964) ; consequently, the formation name is herein 

abandoned.

Jurassic strata are present in east-central Alaska 

(figs. 10 and 115) but have not been studied in 

detail. The rocks are poorly exposed, and the stratigraphic succession has not been completely determined. Two facies are present, one of shale, siltstone, and argillite in the Kandik and Nation Rivers 

area (Brabb, 1969, 1970; Brabb and Churkin, 1969), 

and the other of sandstone, quartzite, and shale in 

the Porcupine, Coleen, and Sheenjek Rivers area 

(Brosge and Reiser, 1964, 1969; Maddren, 1912; 

Maddren and Harrington, 1914; Mertie, 1929, 1930). 

Sandstone and quartzite of the Porcupine River 

area contain a Hettangian fauna and probably represent the initial sediments in a southward-expanding 

northern Alaska-Yukon Territory sea (Jeletzky, 

1962). The sea continued to expand and is believed 

to have connected northern and southern Alaska 

through Middle and early Late Jurassic time (figs. 

2-9). Volcanic rocks dated at 155 to 165 m.y. (Reiser

and others, 1965) are present in the Christian area 

northwest of Porcupine and may indicate tectonic 

activity associated with uplift and subsequent subaerial erosion during the later part of Late Jurassic 

time.

OCCURRENCES OF JURASSIC UNCONFORMITIES

SOUTHERN ALASKA

The presence of unconformities in southern Alaska 

has been fairly well established (fig. 12). The lowest 

known unconformity is at the top of Lower Jurassic 

volcanic rocks north of Cook Inlet (Detterman and 

Hartsock, 1966, p. 69, 71; Grantz and others, 1963, 

p. B58) ; it represents a time of pronounced folding, 

and, on the basis of ammonites from the Talkeetna 

Mountains, must have formed during the latest 

Toarcian and the earliest Bajocian time (Leioceras 

opalinum zone). In the Wrangell Mountains, an 

unconformity possibly formed at the same time 

occurs between the Nizina Mountain and Lubbe 

Creek Formations (MacKevett, 1969, p. A41, A44).

The next higher well-recognized unconformity in 

southern Alaska formed during the later part of 

late Bajocian time. It is most clearly shown on the 

Iniskin Peninsula (Detterman and Hartsock, 1966, 

p. 35, 40) where the Bowser Formation of Bathonian 

Age cuts across 420 feet of the Twist Creek Siltstone of early late Bajocian Age onto beds of late 

middle Bajocian Age. The same unconformity is 

probably represented also on the Alaskan Peninsula 

in the lower part of a hiatus of middle Bajocian to 

late Bathonian Age. The fact that the youngest 

Bajocian beds exposed at Wide Bay are as old as 

early middle Bajocian (Otoites sauzei zone) is probably a result of differential erosion such as occurred 

on the Iniskin Peninsula. Such a possibility is supported by the presence on Alinchak Bay of Inoceramus ambiguus Eichwald (Mesozoic loc. 12390), 

which in Alaska is not known in beds older than 

the late middle Bajocian (Stephanaceras humphriesianum zone).

A third unconformity above the base of the Jurassic in the Cook Inlet region formed late in the 

Bathonian. It is marked between Chinitna Bay and 

Tuxedni Bay by northward truncation of the uppermost part of the Bowser Formation. It is marked 

in the Talkeetna Mountains by erosion that locally 

removed all beds equivalent to the Bowser Formation. It may be represented in the Wrangell Mountains in the basal part of a hiatus of probable late 

Bathonian to early Oxfordian Age. It is probably 

represented in the Alaska Peninsula in the upper
OCCURRENCES OF JURASSIC UNCONFORMITIES 15

part of a hitaus between beds of early middle Bajocian and early Callovian Age. On Wide Bay and 

Puale Bay, lower Bathonian sediments were either 

never deposited or were eroded away during late 

Bathonian time. If the latter possibility is true, then 

some Bathonian beds may still be present in the 

subsurface of the Alaska Peninsula.

A fourth unconformity in southern Alaska formed 

during the late Callovian and in some areas persisted into the early Oxfordian. It represents this 

entire time span throughout most of the Alaska 

Peninsula except near Mount Peulik (Mesozoic loc. 

10798) west of Puale Bay. It represents only the 

late Callovian in the Cook Inlet region where middle 

Callovian beds in the upper part of the Chinitna 

Formation are overlain unconformably by the Naknek Formation that basally contains the early Oxfordian ammonite Cardioceras (Detterman and 

Hartsock, 1966, p. 47-49). Farther east in the 

Wrangell Mountains, the unconformity represents 

the upper part of a hiatus that apparently extends 

from late Bathonian to early Oxfordian time.

Another unconformity of latest Jurassic age may 

extend across* most of southern Alaska east of Wide 

Bay as indicated by an absence of such late Tithonian mollusks as Buchia piochii (Gabb) or B. 

fischeriana (d'Orbigny) and by the presence locally 

of beds of Valanginian to Hauterivian Age resting 

on beds of late Kimmeridgian to middle Tithonian 

Age. For example, in the Talkeetna Mountains, the 

uppermost Jurassic beds containing B. rugosa

North-central 

Alaska between

Killikand 

Itkillik Rivers

FIGURE 12. Occurrences of unconformities in the Jurassic of Alaska. Blank spaces indicate strata of known ages; vertical lines indicate strata missing; right diagonal lines indicate beds not exposed; left diagonal lines indicate lack of 

fossil data.
16 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

(Fischer) and B. mosquensis (von Buch) are overlain by conglomerates and sandstones containing 

Buchias of early to middle Valanginian Age (Imlay 

and Reeside, 1954, p. 233; Grantz and others, 1966, 

p. C46). Evidently the unconformity below the 

Valanginian beds could have formed during the late 

Tithonian, or the Berriasian, or the entire time 

interval.

NORTHERN ALASKA

In northern Alaska, only the area east of the 

Lupine River has been studied in sufficient detail 

for the presence and positions of unconformities to 

be fairly well documented. In that area, one unconformity has been dated as late middle Bajocian to 

possibly early Bathonian because the youngest 

known Bajocian beds contain Arkelloceras, and the 

oldest Bathonian beds contain Cranocephalites. A 

slightly higher unconformity may exist at the 

Bathonian-Callovian boundary (see columns 15 and 

16, fig. 11B), although the westward pinchout of 

the Bathonian beds between the Canning and Sagavanirktok Rivers could be depositional against a 

landmass in the area of the Killik and Itkillik Rivers. 

The next higher unconformity has been dated as late 

Callovian because the underlying beds contain 

Cadoceras and Pseudocadocerasl, and the overlying beds contain Cardioceras.

The absence of any ammonites of late Callovian 

Age deserves special mention because beds of that 

age are also absent in Canada (Frebold, 1961, table 

1 opposite p. 26; 1964a, p. 4; Frebold and Tipper, 

1967, p. 18) and have been found in North America 

only in east-central California (Imlay, 1961b, p. 

D6, D27) and in the states of Oaxaca and Guerrero 

in southern Mexico (Burckhardt, 1927; 1930, p. 26, 

32-36, 43; Imlay, 1961b, p. D12). Evidently marine 

waters covered very little of North America during 

late Callovian time.

The existence of other unconformities in northern 

Alaska has not as yet been proven. The fact that the 

latest Tithonian has been identified at only two 

places (Mesozoic Iocs. 26390, M2531) suggests however, that marine deposition was not widespread at 

that time. Also, nondeposition of Upper Jurassic 

beds throughout a large area in north-central Alaska 

is indicated by the fact that to date only Early Cretaceous species of Buchia have been collected in the 

foothills of the Brooks Range between the Killik and 

Itkillik Rivers (Jones and Grantz, 1964), and those 

species were obtained near beds of Late Triassic 

age. Similarly, the reported Late Jurassic age of 

certain beds in the subsurface of north-central 

Alaska is questioned because their age determination was based on species of Foraminifera that were 

originally obtained from the beds just mentioned 

(Tappan, 1955, p. 25).

The sequence of events in northern Alaska during 

the Jurassic both resembled and differed from that 

in southern Alaska. Resemblances include moderately widespread seas from Sinemurian to early 

middle Bajocian time and from Oxfordian to middle 

Tithonian time. Resemblances also include formation 

of unconformities in late Callovian and late Tithonian time. Differences from southern Alaska include the absence of an unconformity in northern 

Alaska at the end of Toarcian time and the formation of an unconformity at a different time during 

Bajocian and Bathonian time. For example, in northern Alaska no ammonites have been found that represent the late middle Bajocian (Stephanoceras 

humphriesianum zone), the late Bajocian, and the 

early Bathonian. In southern Alaska, by contrast, 

that time is well represented, except for the latest 

late Bajocian. If failure to find ammonites of certain 

ages in northern Alaska is not due to inadequate 

collecting, then the advances and retreats of the 

seas in general occurred at different times in northern than in southern Alaska and reflect local diastrophic movements. These differences are probably 

related to times of intrusion and uplift of granitic 

rocks of the Aleutian Range batholith in southern 

Alaska (Detterman and Hartsock, 1966, p. 63, 64, 

69-71).

EXTENT OF JURASSIC SEAS

In the Early Jurassic, the fossil record indicates 

that marine waters spread most widely across southern Alaska during Sinemurian time and most widely 

across northern Alaska during Pliensbachian and 

Toarcian time (figs. 2, 3, and 13). The Sinemurian 

in northern Alaska may be coextensive, however, 

with the geographic range of Otapiria tailleuri Imlay (1967, p. B3-B7, pi. 1, figs. 1-23, pi. 2, fig. 32), 

which species occurs in a distinctive, rather thin 

organic shale and has been found over a distance 

of at least 200 miles north of the Brooks Range between the Etivluk and Itkillik Rivers. Evidence for 

such an extension of the Sinemurian consists (1) of 

a large well-preserved float specimen of Crucilobiceras (Mesozoic loc. 29774 from the same place as 

localities M 2451 and 29280 in Imlay, 1967, p. B7) ; 

(2) four small ammonite molds identical with the 

inner whorls of Crucilobiceras (Mesozoic loc. 29775 

from the same place as locality 24060 in Imlay, 

1967, p. B7) ; (3) similar small ammonite molds 

(Mesozoic Iocs. 29281 and 29282) that previously 

were compared with Tmetoceras and other genera
EXTENT OF JURASSIC SEAS 17

(Imlay, 1967, p. B6, B7); and (4) the association of 

the ammonites with Otapiria tailleuri Imlay at 

USGS Mesozoic localities 29282 and 29775. The inferences from this data are that the Sinemurian sea 

was probably nearly as extensive in northern Alaska 

as the Pliensbachian and Toarcian seas, and in 

Alaska as a whole the Sinemurian sea was nearly 

as extensive as the Bajocian sea.

During Bajocian time, marine waters transgressed 

widely in southern, southwestern, north-central and 

northeastern Alaska and were connected eastward 

with seas in Canada. Near Wide Bay on the Alaska 

Peninsula, deposition continued at least until the 

early middle Bajocian (Parabigotites crassicostatus 

beds), in the Cook Inlet region until the early late 

Bajocian (Megasphaeroceras rotundum beds), and 

in northeastern Alaska until the early middle Bajocian (Arkelloceras beds) (fig. 14). The duration 

of the sea in the Kuskokwim region of southwestern

Alaska is not known because the fossil evidence consists almost entirely of Inoceramus ambiguus Eichwald, which in the Cook Inlet regions range from 

late middle Bajocian (Teloceras itinsae beds) 

through the Bathonian and occurs rarely in beds of 

early Callovian Age. Southeastern Alaska was probably also covered by a sea during at least middle 

Bajocian time, as indicated by occurrences of fossils 

of that age in nearby northwestern British Columbia 

(Frebold and Tipper, 1970, fig. 6 on p. 10). Whether 

the Bajocian sea ever extended across northwestern 

Alaska west of the Okpikruak River must await 

more fieldwork.

During Bathonian time, marginal seas definitely 

occurred in northeastern Alaska east of the Sagavanirktok River and in southern Alaska between the 

Iniskin Peninsula and the Wrangell Mountains (fig. 

5). These clearly were westward extensions of seas 

of that age in central and northern Yukon Terri55

Toarcian

Pliensbachian

Sinemurian

Hettangian

Western Nevada 

(Muller and Ferguson, 

1939; Hallarn, 1965)

Grammoceras and 

Pseudolioceras

Catacoeloceras and 

Dactylioceras

7

Nodicoeloceras

Arieticeras

7

Uptonial

Eoderoceras and 

Crucilobiceras

Oxynoticeras

 >

?

Amioceras, Arietites, 

Coroniceras, and 

Megarietites

Schlotheimia and 

Alsatites

Waehneroceras and 

PsUoceras

Southern and 

eastern Mexico 

(Erben, 1956, 1957)

Lower part of coal- and 

plant-bearing beds

Arieticeras 

7

7

Uptonia

Microderoceras and 

Echioceras

Pleurechioceras 

 >

Vermiceras

Oxynoticeras

Euaga'ssiceras

Amioceras

7

Coroniceras

Not exposed

East-central Oregon 

(Imlay, 1968)

Catulloceras and 

Dumortieria

Haugia and 

Polyplectes

 >

Arieticeras, Reynesoceras, 

Paltarpites, Prodactylioceras, 

and leptaleoceras )

Crucilobiceras

Amioceras )

Schlotheimia 

and Alsatites

Waehneroceras and 

Psiloceras

Southern Alaska 

(Imlay, 1968)

Grammoceras

Haugia and 

Phymatoceras

Dactylioceras cf . 

D. commune

Pleuroceras, Amaltheus, 

and Paltarpites

 >

Uptonia, Apoderoceras, 

and Acanthopleuroceras

Crucilobiceras 

7

Microderoceras 

7

Amioceras

Coroniceras

Waehneroceras

Northern Akska 

(Imlay, 1955)

Pseudolioceras

Dactylioceras cf . D. commune

Dactylioceras cf. 

D. semicelatum 

and Nodicoeloceras

Amaltheus

 >

Crucilobiceras

? ...

Arietites

Psiloceras

FIGURE 13. Correlation of Hettangian to Toarcian ammonite faunas in Alaska.
18 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

tory, Canada (Frebold and others, 1967, p. 11, 12, 

23). The fossil record (fig. 14) indicates that the 

sea in southern Alaska existed during the entire 

Bathonian, and the sea in northeastern Alaska 

existed only during the middle to late Bathonian. 

Marine waters probably did not extend as far southwest as Puale Bay and Wide Bay in the Alaska 

Peninsula, because beds of early Callovian Age rest 

directly on beds of middle Bajocian Age in both 

places. Whether or not the Bathonian sea ever extended westward across north-central and northwestern Alaska must await detailed mapping and 

fossil collecting comparable with that now nearing 

completion in northeastern Alaska. Failure to find 

any Bathonian fossils in southeastern Alaska coincides with an absence of such fossils in western 

British Columbia (Frebold and Tipper, 1967, p. 4; 

1970, p. 12, 16, 17). The Bathonian may be represented in the Kuskokwim region by some occurrences 

of Inoceramus ambiguus Eichwald.

The seas of Callovian time in Alaska were continuations and extensions of the Bathonian seas 

(fig. 5). They extended at least as far southwest as 

Wide Bay on the Alaska Peninsula, whch is 200 

miles beyond the southernmost Bathonian occurrence in the Cook Inlet region. Failure to find any 

megafossils of Callovian Age in north-central and 

northwestern Alaska may have some significance 

paleogeographically but could be due to inadequate 

collecting. Failure to find any Callovian megafosStages

Callovian

Bathonian

B

'S 

o

I

fc

CL. 

CL.

3

T3 o 

E

1

.2

Southern Mexico 

Guerrero and Oaxaco 

(Buickhardt, 1927, 1930; 

Arkell, 1956; Imlav, 1952; 

Erben. 1956, 1?>57)

Peltoceras spp.

Erymnoceras mixtecorum 

7

Reineckeia neogaea

Eurycephalites boesei 

and Xenocephalites

Epistrenoceras paracontrarium

No fossil evidence

Zigzagiceras

Parastrenoceras

"Stephanoceras" and 

Normannites

No fo;,sil evidence

Upper part of coal- and 

plant-bearing beds

Eastern Oregon and California 

(Imlay, 1961b, 1964a, in part)

Peltoceras (Metapeltocerasl) 

(eastern California only)

Lilloettia cf . L. stantoni and 

Pseudocadoceras grewingki

Lilloettia buckmani, 

Xenocephalites vicarius, and 

Kepplerites

Probably represented by

Kepplerites, Cc 

Parareineckeia 

and Choffatia 

Snowshoe For

tbbanites, 

Xenocephalites, 

n upper part of 

mation

No fossil evidence 

7

Spiroceras, Megasphaeroceras, 

Leptosphinctes, and Normannites g

Chondroceras allani, Normannites *> § 

crickmayi, and Teloceras itinsae fe 'g |

Dorsetensia

Parabigotites 

crassicostatus

IL-is

Papilliceras E!

and s

Witchellia §

S3

Sonninia (Euhoploceras), Fontannesia , 

Docidoceras, Hebetoxyites, 

Praestrigites, and Strigoceras

Tmetoceras scissum, Praestrigites, 

and Eudometoceras

Tmetoceras scissum

No fossil evidence

Southern Alaska 

(Imlay, 1953b, 1962a,b, 1964b; 

Westermann, 1964, 1969)

No fossil evidence 

7

Cadoceras (Stenocadoceras) stenoloboide

Lilloettia buckmani, *, ^> Cadoceras catostoma , and -g

C. (Paracadoceras) tonniense \

t SDisconformity ^ -^^"^ ^

Arctocephalites cf. A. elegans

Cranocephalites

Cranocephalites costidensus

Angular unconformity on Iniskin Peninsula

Megasphaeroceras rotundum, Normannites, 

Leptosphinctes, and Sphaeroceras

Chondroceras allani , Normannites « 

crickmayi, and Teloceras itinsae fe -.

 * «

Papilliceras, ^ ** Witchellia, Normannites

Otoites, 

Emileia, Parabigotites crassicostatus, 

Dorsetensia, Dorsetensia adnata, and 

and Stephanoceras juhlei 

Bradfordia 9

? i

Witchellia sutneroides ^

Sonninia (Euhoploceras) Docidoceras g ^ 

and S. (Alaskoceras) widebayense % ^ 

Docidocerasl paucinodosum *

Erycitoides howelli, Erycites, g 

and Tmetoceras <S£

Tmetoceras scissum

No fossil evidence

Northern Alaska 

(Imlay, 1955)

No fossil evidence

7

Cadoceras, and 

Pseudocadoceras 

grewingki

Not known

Arcticoceras kochi

7

Arctocephalites elegans

Cranocephalites

No fossil evidence

7

Arkelloceras

No fossil evidence

Erycitoides howelli 

and Tmetoceras

7

Pseudolioceras 

maclintocki

FIGURE 14. Correlation of Bajocian to Callovian ammonite faunas in Alaska.
EXTENT OF JURASSIC SEAS 19

sils in the Wrangell Mountains is probably related 

to a disconformity of pre-late Oxfordian Age at the 

base of the Root Glacier Formation (MacKevett, 

1969, p. A46). The fossil record (fig. 14) indicates 

that the sea withdrew entirely from Alaska at the 

end of the middle Callovian.

Early in the Oxfordian, marine waters covered 

the same areas in Alaska as during the Callovian 

(compare figs. 5 and 6), but later in the epoch and 

during the early Kimmeridgian they spread widely 

across both northern and southern Alaska (fig. 7). 

Evidently in southern Alaska the sea spread over an 

uneven terrain south of mountains that shed much 

conglomerate and sandstone into the sea (Betterman and Hartsock, 1966, p. 49, 71). The uneven 

character of the terrain is shown by the fact that 

the basal beds of the Oxfordian sequence contain 

the early Oxfordian ammonite Cardioceras in four 

areas, whereas in the Wrangell Mountains and at 

most places on the Alaska Peninsula the basal beds 

contain the younger ammonite Amoeboceras and 

its associate Buchia concentrica (Sowerby) (figs. 

11A and 15). Failure to find any Oxfordian or early 

Kimmeridgian fossils in the Kuskokwim region or 

in southeastern Alaska suggests that rocks of that 

age are missing in those areas, but more verification 

is needed before paleogeographical conclusions can 

be drawn.

Stages

Tithonian

Kimmeridgian

Oxfordian

8. § 

»

1 I

1o

1

1

2.

i

i°

Eastern and northern Mexico 

(Imlay, 1943, 1952; 

Erben, 1957)

Substeuroceras and "o

Proniceras - * *, 

8 § 2 

5! fc £

 ? .gg-5

l|i

Kossmatia, « « | 

Durangites, and g ^ 5; 

Corongoceras

 >

Pseudolissoceras 

and 

Subplanites -o 5$

Hi tt

S 8 Mazapilites ^ .g

£ -^

1

Hybonoticeras cf. 

H. beckeri

Idoceras durangense and 

Glochiceras flalar

Idoceras balderum

Sutneria cf. S. platynota

Discosphinctes caribbeanus and 

Ochetoceras canaliculatum

Dichotomosphinctes 

durangensis

Not identified

Creniceras and 

Parapaltoceras locally

California, Oregon, and 

western Idaho 

(Imlay, 1953a;196)b; 

Imlay and Jones, 1970)

Substeueroceras Buchia aff. 

and Spiticeras B. okensis 

...... . ., . ?

Parodontoceras 

?

Buchia piochti 

Kossmatia

 >

Not identified

Amoeboceras (Amoemtes) 

and Idoceras «

'£

1

Discosphinctes virgulatus and ;S

Dichosphinctes mulbachi jj°o

Cardioceras martini 

(Idaho only)

Southern Alaska 

(Imlay, 1953b, 1961a)

Buchia piochii and B. flscheri 

_,_ ? ...

B. rugosa and B. masquensis

.8

1 Amoeboceras "£

(Prionodoceras) 8 

spiniferum and ^ 

Dichotomosphinctes jj

35

Cardioceras distans

C. (Scarburgicerac.) martini

Not identified

Northern Alaska 

(Imlay, 1955)

Buchia cf . B. fischeriana 

 >

B. rugosa and B. mosquensis

?

'C

1 

§ Amoeboceras %

g

(Prionodocems) S

1

Cardioceras (Scarburtfceras)

Not identified

FIGURE 15. Correlation of Oxfordian to Tithonian molluscan faunas in Alaska.
20 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

From late Kimmeridgian until middle Tithonian 

time (fig. 8) marine waters spread even more widely 

over Alaska. They covered large parts of the Kuskokwim region and of southeastern Alaska, and, to 

judge by the fossil record, covered more of Alaska 

than at any other time during the Jurassic. The 

absence of Jurassic sediments younger than early 

Kimmeridgian in the area between Iniskin Bay and 

Tuxedni Bay on Cook Inlet is probably due to Late 

or post-Jurassic uplift and erosion (Detterman and 

Hartsock, 1966, p. 71) rather than to nondeposition.

During late Tithonian time, the marginal seas in 

Alaska became much reduced, compared with those 

of the immediately preceding time (compare figs. 

8 and 9). One sea covered most of the present site 

of the Alaska Peninsula southwest of Wide Bay. 

Another sea existed in an area now occupied by the 

eastern part of the Alaska Range and apparently 

extended eastward into the Yukon Territory (Frebold and Tipper, 1970, p. 15; Frebold and others, 

1967, p. 10). Failure to find any marine fossils of 

that age elsewhere in southern Alaska could be explained by erosion or by nondeposition, or both. In 

southeastern Alaska the sequence exposed on Admiralty Island (Loney, 1964, p. 59, 92, 97) apparently represents continuous deposition from Kimmeridgian until Valanginian time. In northern 

Alaska, the geographic position of a single specimen 

of Buchia cf. B. fischeri (d'Orbigny) indicates the 

presence of a fairly widespread sea that presumably 

extended eastward into the northern Yukon 

(Jeletzky, 1958, p. 5, 1960, p. 4; 1966, p. 25, 30; 

1967, p. VI; Frebold and others, 1967, p. 10).

In summation, Jurassic marginal seas occupied 

considerable areas in northern, southern, and southwestern Alaska, but probably never covered a huge 

area in central Alaska or a southwestern prolongation of that area. From the presently known fossil 

occurrences (figs. 2-9), it is inferred that marine 

waters were absent during late Callovian time, 

much restricted during Hettangian, Bathonian, 

early Oxfordian and late Tithonian time, somewhat 

less restricted during Pliensbachian, Toarcian, and 

Callovian time, fairly widespread during Sinemurian, Bajocian, and late Oxfordian to early Kimmeridgian time, and most widespread in late Kimmeridgian to middle Tithonian time.

SUCCESSION AND DIFFERENTIATION OF 

AMMONITES

Most of the Early Jurassic ammonites of Alaska 

are identical with and occur in essentially the same 

succession as ammonites of that age in central and 

northern Europe and in Canada (fig. 13). In fact,

the Alaskan ammonites of late Pliensbachian Age 

have more in common with the ammonites of those 

areas than with late Pliensbachian ammonites of 

eastern Oregon, which have Mediterranean affinities 

(Imlay, 1968, p. C21). Such close resemblances eastward across Canada show that the seaways between 

Alaska and northwest Europe were open during 

Early Jurassic time. They suggest that continental 

drift either did not occur during that time or had 

no influence on the distribution of ammonites between those areas.

The succession of ammonites in Alaska during 

Bajocian time (fig. 14), as previously discussed 

(Imlay, 1965, p. 1030), was similar to that in Europe 

and in the Tethyan region except for the presence 

in Alaska of a few genera that have been found 

only in areas near the Pacific Ocean and the absence in Alaska of a few genera that are fairly 

common in Europe. These differences were slight 

during the early Bajocian but became more pronounced by late Bajocian. In southern Alaska, the 

succession ended early in late Bajocian time. In 

northern Alaska the succession ended in early middle 

Bajocian time.

The succession of ammonites in Alaska during 

Bathonian time (fig. 14) was essentially identical 

with that in northern Canada (Frebold, 1964b), in 

East Greenland (Callomon, 1959), and in other lands 

bordering the Arctic Ocean. It was dominated by 

the genera Cranocephalites, Artocephalites, and 

Arcticoceras. It had almost nothing in common 

generically with the Bathonian ammonite assemblages of central Europe and the Tethyan region 

(Imlay, 1965, p. 1024, 1030, 1031). In southern 

Alaska, however, the Bathonian ammonite succession includes genera, such as Parareineckeia and 

Xenocephalites, that are known only from the Western Hemisphere. Evidently the Bathonian ammonites 

of the Boreal region were almost completely separated from Bathonian ammonites farther south by 

barriers of some kind, except along the Pacific 

Coast south of Alaska. As a consequence, the ammonite faunas of the world became differentiated 

into distinct Boreal and Tethyan realms and a somewhat less distinct Pacific realm.

A Callovian ammonite succession has been established in Alaska only in the southern part between 

the Talkeetna Mountains and Wide Bay on the 

Alaska Peninsula (fig. 14). This succession is essentially the same as along the Pacific Coast in British 

Columbia (Frebold and Tipper, 1967, p. 5), Oregon 

(Imlay, 1964a, p. D7-D10), and California (Imlay, 

1961b, p. D5). It is characterized by such taxa as
FOSSIL OCCURRENCES BY STAGES 21

Cadoceras, C. (Paracadoceras), C. (Stenocadoceras), 

Pseudocadoceras, Kepplerites, Lilloettia, and Xenocephalites; the first five are of Boreal origin, and 

the last two originated in seas of the Western 

Hemisphere. Except for Lilloettia and Xenocephalites, the succession has very little in common 

generically with ammonites of that age in Mexico 

and even less in common with ammonites of the 

Mediterranean region, as discussed elsewhere (Imlay, 1953b, p. 56; 1965, p. 1023-1033). It bears no 

resemblances on the specific levels to ammonites in 

the western interior of the continent and in northern 

Canada (Imlay, 1953a; Frebold, 1961, p. 17-22; 

1964a, p. 4, 1964b. The succession differs even more 

with ammonites of the same age in Greenland and 

northern Eurasia (see comparisons in Frebold, 

1961). Overall, the Callovian ammonites of southern 

Alaska are dominantly of Boreal origin but are in 

part of local origin and in part of Pacific origin.

The succession in Alaska of ammonites of Oxfordian to early Kimmeridgian Age (Imlay, 1952, p. 

977-978) (fig. 15) is nearly the same as that along 

the Pacific Coast from British Columbia to California (Frebold and Tipper, 1967, p. 5; Imlay, 

1961b, p. D5, 1964a, D7-10). It is likewise identical 

with, or closely similar to, the succession in the 

western interior of the continent and in northern 

Canada (Frebold and others, 1959, 1967, p. 10; 

Frebold, 1964b, p. 481). It can be correlated with 

ammonite successions in East Greenland and northern Eurasia by means of Cardioceras and Amoeboceras but otherwise differs by having far fewer 

genera (see comparisons in Frebold, 1961, table 1). 

The succession has nothing in common with ammonites of that age in Mexico or in the Mediterranean region, except for the presence of Dichotomosphinctes.

An ammonite succession has not been established 

in the uppermost Jurassic beds of Alaska. A few 

specimens of Lytoceras and Phylloceras occur in beds 

of middle Kimmeridgian to middle Tithonian Age 

which are identified by the presence of Buchia 

rugosa (Fischer) and B. mosquensis (von Buch). 

The very latest Jurassic, characterized by Buchia 

piochii (Gabb), has not furnished any ammonites. 

This scarcity of ammonites in Alaska in beds 

younger than early Kimmeridgian is in marked 

contrast to a fair abundance of ammonites in equivalent beds in East Greenland and northern Eurasia. 

As a consequence of this scarcity, most correlations 

above the lower Oxfordian are made on the basis 

of species of Buchia whose succession during the 

Late Jurassic appears to be the same throughout 

the Arctic.

The succession of Jurassic ammonites in Alaska, 

in comparison with successions in other parts of the 

world, shows that differentiation into Boreal and 

Tethyan realms started in late Pliensbachian time, 

increased gradually during the Bajocian, was completed by the Bathonian, and persisted into the 

Early Cretaceous. Evidently faunal differentiation 

during Bathonian and later Jurassic time coincides 

very well with the deposition of Jurassic salt and 

some associated red beds in the Gulf of Mexico 

region (Imlay, 1943, p. 1438, 1508, 1509; Bishop, 

1967, p. 249; Viniegra-0, 1971, p. 478-484; fig. 10 

on p. 492) which apparently coincides in time with 

early stages of continental drift. Faunal differentiation probably resulted from a combination of events 

(Imlay, 1965) which may include the separation of 

the continents.

In summation, the ammonite succession in Alaska 

from Hettangian to Toarcian time is essentially the 

same as that in central and northern Europe. It is 

also similar to that in the Mediterranean region 

except for certain ammonites of late Pliensbachian 

Age. The Bajocian ammonite succession in Alaska 

is likewise similar to that in the above-named regions except for a few genera known only from 

areas bordering the Pacific Ocean. In contrast, the 

Bathonian succession in Alaska is dominated by the 

Boreal genera Cranocephalites, Arctocephalites, and 

Arcticoceras, which are unknown in central Europe 

or farther south. The Callovian ammonite genera 

of Alaska are likewise dominantly Boreal in origin, 

but, as in the Bajocian and Bathonian ammonites, 

include some genera that are known only from the 

Western Hemisphere. During the rest of Jurassic 

time, ammonites became uncommon in Alaska but 

include the Boreal genera Cardioceras of early Oxfordian Age and Amoeboceras of late Oxfordian to 

early Kimmeridgian Age.

FOSSIL OCCURRENCES BY STAGES

Locality in 

figure 2 Description

Hettangian

3__USGS Mesozoic Iocs. 29737 and 29738. From Spike 

Mountain near the Porcupine River about 30 miles 

north of Old Rampart, Coleen quadrangle, lat 

63°35.75' N., long 141°40' W. Psiloceras.

8__USGS Mesozoic Iocs. 29890 and 29891. About 15 miles 

northeast of McCarthy, northern part of sec. 26, 

T. 4 S., R. 16 E., near NW. cor. McCarthy B-4 

quadrangle, southern Wrangell Mountains, eastern 

Alaska. Waehneroceras and Psiloceras.
22 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

Locality in 

figure 2 Description

Hettangian Continued

11__USGS Mesozoic loc. 29874. East bank of Alien River 

at middle rapids, Tikchik Lakes area, lat 60°7' N., 

long 158°38' W., Taylor Mountains A-8 quadrangle. Kuskokwim region, southwest Alaska. Weyla 

and other pelecypods identical with species in basal 

Jurassic near Seldovia on the Kenai Peninsula (loc. 

13). These could be of Hettangian or Sinemurian 

Age.

12 USGS Mesozoic loc. 24357. Hagermeister Island in 

Bristol Bay area, lat 58°43'50" N., long 160°58'10" 

W. Kuskokwim region, southwest Alaska. Weyla 

and other pelecypods identical with species near 

Seldovia (loc. 13). These could be Hettangian or 

Sinemurian Age.

13__USGS Mesozoic Iocs. 21242 and 22664. From 2.8 to 

2.95 miles S. 67° W. of Pt. Naskowhak on south 

shore of Kachemak Bay, Seldovia B-5 quadrangle, 

Kenai Peninsula. Waehneroceras.

14__USGS Mesozoic Iocs. 3110, 12394, 19803, 25694 and 

29268 on peninsula between Puale Bay and Alinchak 

Bay about 1 mile N. 65° W. of Cape Kekurnoi, 

Alaska Peninsula. Waehneroceras.

15 Richfield Oil Co. Wide Bay test well 1, core 5 at 

depth of 2,235 to 2,236 feet, on north side of Wide 

Bay, Alaska Peninsula. Waehneroceras.

Sinemurian

1__Avak test well 1 at depth of 1,836 feet on Point 

Barrow, northern Alaska (See Imlay, 1955, p. 82, 

87). Arietites.

2____USGS Mesozoic loc. 29774. On Blankenship Creek in 

Lisburne Ridge area west of Etivluk River, lat 

68°37.5' N., long 156°42.5' W., northwest Alaska. 

Crucilobiceras.

4__USGS Mesozoic loc. 16229. Head of small eastern 

tributary of Partin Creek that heads against Little 

Shotgun Creek north of Eldridge Glacier on west 

side of Chulitna Valley, eastern Alaska. Arnioceras.

5__USGS Mesozoic loc. 26722. Talkeetna Mountains A2 quadrangle, coordinates 1.20, 17.23, lat 62°59'58" 

N., long 147°57'48" W. Mesozoic loc. 28661 in Talkeetna Mountains A-3 quadrangle, coordinates 15.35, 

15.63, lat 62°13'29" N., long 148°01'27" W. Talkeetna Mountains, Cook Inlet region. Crucilobiceras.

6__USGS Mesozoic loc. 27586. Carbon Creek, 2.3 miles S. 

7° E. of its mouth, which enters Matanuska River 

from south near mouth of Chickaloon River, near 

south boundary of sec. 12, T. 19 N., R. 5 E., Anchorage D-4 quadrangle, Cook Inlet region. Arnioceras.

7__USGS Mesozoic loc. 30137. Near center of north half 

of SW% sec. 8, T. 4 S., R. 11 E., in south-central 

part of McCarthy (C-7) quadrangle. Mesozoic Iocs. 

30138-30140 in west half of sec. 17, T. 4 S., R. 12 

E., near southeast corner of McCarthy (C-7) quadrangle. Wrangell Mountains, eastern Alaska. All localities are in upper member of McCarthy Formation. Arnioceras (loc. 30140), Megarietitest, and 

Arniocerasl (loc. 30139), and arietitid ammonites 

(Iocs. 30137 and 30138).

Locality in 

figure 2 Description

Sinemurian Continued

8__Many localities in upper member of McCarthy Formation, in McCarthy C^4, C-5, and B-4, quadrangles, 

Wrangell Mountains, eastern Alaska (MacKevett, 

1970a, b, 1971). Ammonites include Arietites (loc. 

29870), Arnioceras (Iocs. 28535, 28536, 28538, 

28688), Crucilobiceras (loc. 28537, 28540, 28671-73), 

and Microderoc,eras (loc. 14472).

9__USGS Mesozoic loc. 29773. Float, sec. 37, T. 23 S., 

R. 35 E., Yakutat D-4 quadrangle, southeast Alaska. 

Crucilobiceras.

10__Property of State Museum at Juneau. Ammonite 

found near center of face of Norris Glacier about 

14 miles northeast of Juneau. Juneau B-l quadrangle, southeast Alaska. Xipheroceras"!

11__.Described under Hettangian fossil occurrences.

12__Do.

13.__USGS Mesozoic loc. 2981. Two miles west of Pt. 

Naskowhak on west side of Seldovia Bay. Seldovia 

B-5 quad., Kenai Peninsula. Coroniceras.

14__USGS Mesozoic Iocs. 3111, 12396, and 21237 on east 

side of Puale Bay about 8,400 feet northwest of 

Cape Kekurnoi, Alaska Peninsula. Coroniceras.

Locality in 

figure 3 Description

Pliensbachian

1__South Barrow test well 3 at depths of 2,069 to 2,198 

feet, Point Barrow, northern Alaska (Imlay, 1955, 

p. 82, 87; Howarth, 1958, p. XXVI). Amaltheus spp.

2__Simpson test well 1 at depth of 5,680 feet, southeast 

of Point Barrow, northern Alaska. (Imlay, 1955, 

p. 82, 87). Amaltheus sp.

4__USGS Mesozoic loc. M2441. Ipewik River, De Long 

Mountains, lat 68°37' N., long 164°11' W. Mesozoic 

loc. 29164 on east bank Ipewik River, lat 68°40' N., 

long 164° 13' W., northern Alaska. Amaltheus sp.

7__USGS Mesozoic loc. 29165. Three miles east of Shrader 

Lake, lat 69°22' N., long 144°48' W., near head 

of Sadlerochit River, northern Alaska. Amaltheus.

8__USGS Mesozoic loc. 30074. West side of Aichilik River 

about 2 miles west of VABM ATTE, lat 69° 33' N., 

long 143°05' W., from 800-1,000 feet above base of 

Kingak Shale. Amaltheus cf. A. stokesi (J. 

Sowerby).

9__USGS Mesozoic loc. 29340. Float from bluff on the 

Middle Salmon Trout River near Old Rampart, 

Kandik area, east central Alaska. Amaltheus. 

10___Many USGS Mesozoic localities in the Talkeetna 

Mountains A-3 quadrangle and the Anchorage D1 and D-2 quadrangles, Talkeetna Mountains, Cook 

Inlet region. Paltarpites, Harpoceras, Arieticeras, 

Leptaleoceras, Fontanelliceras, Amaltheus, Protogrammoceras, Fanninoceras, and Acanthopleuroceras.

11__USGS Mesozoic loc. 28675, SW^SW^ sec. 23, T. 

4 S., R. 16 E., McCarthy C-4 quadrangle. Less than 

100 feet below Lubbe Creek Formation. Uptonia. 

Mesozoic loc. 28531 on east side of McCarthy Creek, 

probably a little northwest of center of sec. 25, T. 

3 S., R. 14 E., McCarthy C-5, quadrangle, southern 

Wrangell Mountains, Lubbe Creek Formation. 

Arieticeras.
FOSSIL OCCURRENCES BY STAGES 23

Locality in 

figured Description

Toarcian

1-_South Barrow test well 3 at depths of 1,772 to 2,063 

feet at Point Barrow, northern Alaska (Imlay, 

1955, p. 82, 87-89). Catacoeloceras at 2,063 feet. 

Dactylioceras at 1,772 to 2,018 feet.

3__USGS Mesozoic Iocs. 29159-29161, 29163. North bank 

of Thetis Creek, lat 68°41'50" N., long 164°45'05" 

W., northwestern Alaska. Harpoceras cf. H. 

exaratum (Young and Bird) and Dactylioceras. 

Mesozoic loc. 29776 near Thetis Creek, lat 68°40.8' 

N., long 164M5.5' W., Harpoceras.

5 __USGS Mesozoic loc. 23772 and 24035 (Imlay, 1955, p. 

80, 89). Pseudolioceras.

6__USGS Mesozoic loc. 22081 (Imlay, 1955, p. 80). Harpoceras cf. H. exaratum (Young and Bird) (not 

Pseudolioceras).

10__Many USGS Mesozoic localities in the Talkeetna 

Mountains A-l, A-2, and A-3 quadrangles, the 

Anchorage D-2 and D-5 quadrangles, and the 

Valdez D-8 quadrangle, Talkeetna Mountains, Cook 

Inlet region. Dactylioceras, Harpoceras, Grammoceras, Haugia, Phymatoceras, and Pseudolioceras.

11__USGS Mesozoic Iocs. 28546-28548, 28678, and 28679 

in southern part of McCarthy C-5 quadrangle, 

southern Wrangell Mountains. Upper part of 

Lubbe Creek Formation. Weyla dufrenoyi 

(d'Orbigny), identified by S. W. Miiller.

12__USGS Mesozoic loc. 19804. East shore of Puale Bay 

about 9,500 feet northwest of Cape Kekurnoi, Alaska 

Peninsula. Haugia.

Locality in 

figure 4 Description

Bajocian

1-_South Barrow test well 2 at depth of 2,391 feet near 

Point Barrow, northern Alaska (Imlay; 1955, p. 

82, 89). Tmetoceras.

2 Topogaruk test well 1 at depth of 8,113 feet about 

58 miles south-southeast of Point Barrow, lat 

70°37'30" N., long 155°53'36" W., northern Alaska 

(Imlay, 1955, p. 82, 89). Tmetoceras.

3___USGS Mesozoic loc. 24035. Canning River, lat 

69°34' N., long 146°23' W., northern Alaska (Keller 

and others, 1961, p. 193). Pseudolio&eras maclintocki 

(Haughton) and Oxytoma jacksoni (Pompeckj).

4__USGS Mesozoic Iocs. 29152-29156. West end of Ignek 

Valley, lat 69°41' N., long 145°36' W. to lat 69°33' 

N., long 145°43' W., northern Alaska. Pseudolioceras 

maclintocki (Haughton), Erycitoides cf. E. howelh 

(White), Canaverella cf. C. belophora Buckman, 

and Inoceramus cf. /. lucifer Eichwald.

5__USGS Mesozoic loc. 29147 at junction of Sadlerochit 

and Kekiktuk Rivers, lat 69°33' N., long 144°43' 

W.; Mesozoic loc. 29150 on Fire Creek in central 

part of Ignek Valley, lat 69°32' N., long 145°09 

W.; Mesozoic loc. 29880 on Fire Creek, lat 69°32'22' 

N., long 145°12'30" W.; Mesozoic Iocs. 29884 to 

29886 on Kaviak Creek, 0.7 miles SW. of Sadlerochit 

River, lat 69°29' N., long 145°03' W.; Mesozoic 

Iocs. 10307 and 10308 (Imlay, 1955, p. 81). Northeastern Alaska. Pseudolioceras maclintocki (Haughx>cality in 

figure 4 Description

Bajocian Continued

ton), Erycitoides, Canavarella (loc. 29884 only), 

and Inoceramus lucifer Eichwald.

6__USGS Mesozoic loc. 29157 on Canning River near 

Shublik Island, lat 69°24' N., long 146°10' W., northern Alaska, Mesozoic Iocs. 21023 and 22595 (Imlay, 

1955, p. 80). Pseudolioceras whiteavesi (White) 

(loc. 21023 only) and P. maclintocki (Haughton); 

Mesozoic Iocs. 29138-29142, Canning River near 

Shublik Island, lat 69°24' N., long 146° 10' W., 

northeastern Alaska. Arkelloceras; Mesozoic Iocs. 

21024, 22597, and 24033 on west bank of Canning 

River opposite mouths of Eagle and Cache Creeks, 

lat 69°27' N., long 146°13'30" W. (Imlay, 1955, 

p. 80, 91; Keller and others, 1961, p. 193). 

Arkelloceras.

1____USGS Mesozoic loc. 30135 on ridge west of Okerokvik 

River, 7.6 miles S. 80° W. of VABM ATTE, lat 

69°29'45" N., long 143°26' W. Pseudolioceras 

maclintocki ( Haughton).

8__USGS Mesozoic loc. 21552. Cutbank on Fortress Creek, 

lat 68°31' N., long 153°03' W. (Patton and Tailleur, 

1964, p. 444). Pseudolioceras'! and Inoceramus lucifer 

Eichwald.

9__USGS Mesozoic loc. 22591. Cutbank on Tiglukpuk 

Creek, lat 68°20' N., long 151°50' W. (Patton and 

Tailleur, 1964, p. 444). Arkelloceras"! sp. juv. and 

Inoceramus cf. I. lucifer Eichwald.

10__USGS Mesozoic loc. M1717 (Imlay, 1967, p. B8), 

about 3 miles east-southeast of Nation. Otapiria 

sp. undet. and Pentacrinus subangularis alaska 

Springer. This variety of Pentacrinus has been 

found in the northeast Alaska near the Sadlerochit 

River associated with Inoceramus cf. I. lucifer 

Eichwald (Mesozoic loc. 29885) and directly above 

beds containing Canavarella, Pseudolioceras cf. P. 

maclintocki (Haughton), and Inoceramus cf. /. 

lucifer Eichwald (Mesozoic loc. 29884) of early 

Bajocian Age. As the full stratigraphic range of 

the crinoid subspecies has not yet been established, 

its presence alone is not proof of a Bajocian Age. 

11__USGS Mesozoic loc. 13430. Northwest side of Innoko 

River, about 30 miles airline upstream from confluence of Innoko and Iditarod Rivers, Innoko 

District, Kuskokwim region, Alaska, Inoceramus 

cf. /. ambiguus Eichwald.

12__USGS Mesozoic loc. 27716. East bank of Yukon River 

about 7 miles N. 25° W. from village of Ohogament, 

coordinates 0.65, 11.35, lat 61°39' N., long 161°55.5' 

W., Russian Mission quadrangle, Kuskokwim region. 

Stephanocerasl sp. Probably Middle Jurassic. 

13__USGS Mesozoic loc. 21481 on south side of Tuluksak 

River, 2.7 miles S. 55° W. of Nyac, and 1.5 miles 

N. 50° W. of Nyac hydroelectric power plant; 

Mesozoic loc. 21029 on north side of Tuluksak River 

about 1 mile north of loc. 21481, Bethel quadrangle, 

Kuskokwim region, southwest Alaska (Hoare and 

Coonrad, 1959a). Inoceramus ambiguus Eichwald. 

14__USGS Mesozoic loc. 27091. Crest of low ridge 12.7 

miles S. 59° W. from junction of Buckstock and
24 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

Locality in 

figure 4 Description

Bajocian Continued

Aniak Rivers and 6.8 miles N. 55° E. of Mt. Hamilton, coordinates 20.5, 4.4. Russian Mission quadrangle, Kuskokwim region, southwest Alaska. 

Inoceramus cf. /. ambiguus Eichwald.

15__USGS Mesozoic loc. 21031. About 3 miles west of 

Salmon River, about 23.5 miles S. 36° E. of Mt. 

Hamilton, Kuskokwim region, southwest Alaska 

(Hoare and Coonrad, 1959b). Inoceramus cf. /. 

ambiguus Eichwald.

16__USGS Mesozoic loc. 20717. About 4V2 miles S. 6° E. 

of confluence of Cripple Creek with Salmon River, 

about 23.5 miles E. 36° E. of Nyac, Bethel quadrangle, Kuskokwim region, southwest Alaska (Hoare 

and Coonrad, 1959b). Inoceramus cf. I. ambiguus 

Eichwald.

17__USGS Mesozoic loc. 19729. Cutbank southeast of 

Holokuk River, 27 miles S. 20° E. of Napaiment 

and 3.6 miles upstream (southwest) from mouth 

of Boss Creek, Kuskokwim region, southwest 

Alaska. Inoceramus sp.

18__USGS Mesozoic loc. 19395b. East of Holitna River, 

4 1/& miles S. 42° E. of Nagamut, Kuskokwim region, 

southwest Alaska. Inoceramus cf. /. ambiguus 

Eichwald.

19__USGS Mesozoic loc. 29889. South-central part of 

Hagemeister Island, Bristol Bay, lat 58°38'25" N., 

long 160°58'50" W. Inoceramus cf. /. ambiguus 

Eichwald.

20__USGS Mesozoic loc. 28682, in part. Near center 

SE%NW% sec. 20, T. 3 S., R. 16 E., McCarthy C5 quadrangle, southern Wrangell Mountains, eastern 

Alaska (MacKevett, 1963; 1971). Normannites cf. 

N. variabilis Imlay and Teloceras cf. T. blagdeni 

(Sowerby) obtained with Cranocephalites, Parareineckeia, and Cobbanites as float derived from a 

fairly thin sequence.

21__Many USGS Mesozoic localities in Talkeetna Mountains A-l and A-2 quadrangles and Anchorage 

D-2, D-3, and D-4 quadrangles, Talkeetna Mountains, Cook Inlet region (Imlay, 1962a, p. A5, A6, 

1964b, p. B2, B22, B27).

22 and

23_Many USGS Mesozoic localities from area between 

Iniskin Bay and Tuxedni Bay, north side of Cook 

Inlet (Imlay, 1961a, p. A-5, 1964b, p. B22-B27).

24__USGS Mesozoic loc. 29115. Iliamna Lake region, 2.1 

miles N. 30° E. of mouth of Amakdedori Sreek, lat 

59°18'25" N., long 154°05'40" W., coordinates 1.25, 

4.95, Iliamna B-3 quadrangle, Cook, Inlet region. 

Inoceramus ambiguus Eichwald.

25__USGS Mesozoic loc. 12390. Half a mile south of head 

of Alinchak Bay, Alaska Peninsula. Inoceramus 

lucifer Eichwald (5 specimens) and /. ambiguus 

Eichwald (1 specimen found loose at bottom of 

cliff).

26__Many localities near Wide Bay, Alaska Peninsula 

(Imlay, 1964b, p. B18; Westermann, 1964, 1969).

Locality in 

figure 5 Description

Bathonian

1__USGS Mesozoic Iocs. 28817, 29143, 29144, 29435, 

29855, 29875 to 29877. Central part of Ignek Valley, lat 69°33'30"-34' N., long 145°20' W., northeastern Alaska. Arcticoceras, Arctocephalites 

Cranocephalites, and Inoceramus cf. /. ambiguus 

Eichwald.

2__USGS Mesozoic loc. 22083. North bank of Sadlerochit River, between Gravel and Fire Creeks, lat 

69°31' N., long 145°02" W., northeastern Alaska. 

Arctocephalites ?.

3__USGS Mesozoic loc. 21023 (in part), Canning River 

at mouth of Eagle and Cache Creeks, lat 69°25' 

N., long 146°08' W., Arcticoceras; Mesozoic loc. 

22596, west side of Canning River, lat 69°23'30" 

N., long 146°07'30" W., Arcticoceras; Mesozoic 

loc. 29146, Canning River near Shublik Island, 

lat 69°24' N., long 146°10' W. Arctocephalites.

4__USGS Mesozoic loc. 29145, west end of Ignek Valley, lat 69°33' N., long 145°50' W. Arctocephalites.

5__USGS Mesozoic loc. 30075. Aichilik River, lat 

69°33' N., long 143°05' N., northeastern Alaska. 

Arcticoceras ishmae (Keyserling) and Choffatia"! 

sp.

7__Many USGS Mesozoic localities in the Nizina Mountain Formation in southeastern part of McCarthy 

C-5 quadrangle, southern Wrangell Mountains 

(Mackevett, 1969, p. A42-A45). Parareineckeia, 

Cobbanites, Cranocephalites, and Inoceramus cf. 

/. ambiguus Eichwald. (Most collections are from 

float.)

8__Seven USGS Mesozoic localities in the Talkeetna 

Mountains A-2 quadrangle and one in the Anchorage D-4 quadrangle (Imlay, 1962a, p. C3-C5, 

C16), Talkeetna Mountains, Cook Inlet region, 

Cranocephalites, Parareineckeia, Cobbanites, Oecotraustes, and Inoceramus ambiguus Eichwald.

9___.Peninsula between Tuxedni Bay and Chinitna Bay, 

west side of Cook Inlet. Parareineckeia and 

Cranocephalites in lower two-thirds of Bowser 

Formation (Inlay, 1962a, p. C16, 17, 20; Betterman and Hartsock, 1966, p. 38, 39) are overlain 

by beds containing Arctocephalites cf. A. elegans 

Spath (Mesozoic loc. 22699).

10____Iniskin Peninsula, west side of Cook Inlet. Parareineckeia and Cranocephalites in the lower twothirds of the Bowser Formation are overlain by 

beds containing Keppleritesl (Mesozoic loc. 22553) 

(Imlay, 1962a, p. 16, 17, 20; Detterman and 

Hartsock, 1966, p. 38, 39).

Callovian

5__USGS Mesozoic loc. 30136. Float from beds directly 

overlying the beds at Mesozoic loc. 30075. Cadoceras sp.

6__USGS Mesozoic loc. 22745, West Fork Ivishak River, 

lat 69°0' N., long 148°04'30" W. (Keller and others 

1961, p. 193; Imlay, 1955, p. 80, 90). Pseudocadoceras grewingki (Pompeckj)?, or possibly immature Arcticoceras.
FOSSIL OCCURRENCES BY STAGES 25

Locality in 

figure 5 Description

Callovian Continued

8___Many USGS Mesozoic localities in the Talkeetna 

Mountains A-l and A-2 quadrangles and the 

Anchorage D-3 quadrangle, Talkeetna Mountains, 

Cook Inlet region. Ammonites include most of the 

same genera and species described by Imlay 

(1953b, p. 50). 

9,10__Many localities (see Imlay, 1953b. p. 65-69).

11__USGS Mesozoic loc. 29271, lat 57°57.3' N., long 

155°4.4' W., Kashvik Bay, Karluk quadrangle 

Alaska Peninsula. Cadoceras (Stenocadoceras) 

multieostatum Imlay.

12__Many USGS Mesozoic localities in the Puale Bay 

area, Alaska Peninsula (Imlay, 1953b, p. 63 and 

table 6). Common ammonites include Cadoceras 

tenuicostatum Imlay, C. doroschini (Eichwald), 

and many species of C. (Stenocadoceras) and 

Pseudocadoceras. The abundance of C. (Stenocadoceras) and the absence of C. (Paracadoceras) show that the beds are equivalent to the 

upper part of the Chinitna Formation north of 

Cook Inlet.

13 _A few USGS Mesozoic localities between Jute Bay 

and Portage Bay, Alaska Peninsula (Imlay, 1953b, 

p. 63 and table 6). Cadoceras (Stenocadoceras) 

multieostatum Imlay and Pseudocadoceras grewingki (Pompeckj).

14 Many localities near Wide Bay, Alaska Peninsula 

(Imlay, 1953b, p. 64, 70, 71, and table 6). Same 

ammonites present as in the Chinitna Formation 

north of Cook Inlet.

15 USGS Mesozoic loc. 29342. Axial region of Chignik 

Bay anticline near Conglomerate Creek. Approximate lat 65°26'13" N., long 158°36'48" W., 

Chignik Bay, Alaska Peninsula. Xenocephalitef 

vicarius Imlay.

Locality in 

figure 6 Description

Early Oxfordian

1 USGS Mesozoic loc. 29856. Ignek Mesa in Ignek 

Valley, 6.8 miles S. 75° E. of Katakturuk Canyon, 

lat 69°33'30" N., long 145°20' W., northeast 

Alaska. Cardioceras (Scarburgiceras) .

2 -USGS Mesozoic loc. 29137. Fire Creek in Ignek Valley, lat 69°32' N., long 145°09' W., northeast 

Alaska. Cardioceras (Scarburgiceras).

3__USGS Mesozoic Iocs. 24165, 24166, 24168, 24837, and 

24841. Near headwaters of Little Nelchina River 

in central and east-central part of Talkeetna 

Mountains A-2 quadrangle, Talkeetna Mountains, 

Cook Inlet region. Cardioceras (Scarburgiceras) 

martini Reeside and C. distans (Whitfield). 

4, 5____Many localities between Iniskin Bay and the Hickerson Lake area west of Cook Inlet (Detterman 

and Hartsock, 1966, p. 50, 51). Cardioceras 

(Scarburgiceras) martini Reeside, C. distans 

Whitfield, and C. (Scoticardioceras) alaskense 

Reeside.

Locality in 

figure 6 Description

Early Oxfordian Continued

6__USGS Mesozoic loc. 10798. Five miles southeast of 

Mount Peulik, west of Puale Bay and north of 

Wide Bay, Alaska Peninsula. Cardioceras cf. C. 

canadense Whiteaves.

Locality in 

figure 7 Description

Late Oxfordian to early Kimmeridgian

1__USGS Mesozoic loc. 22126 (Imlay, 1955, p. 78, 79). 

Mesozoic loc. 30071 on Kukpowruk River west 

of Igloo Mountain, lat 68°43' N., long 163°12'30" 

W., Buchia concentrica (Sowerby).

2__USGS Mesozoic loc. 22759 (Imlay, 1955, p. 79, 80). 

Buchia concentrica (Sowerby).

3__USGS Mesozoic loc. 21026 (Imlay, 1955, p. 79, 80). 

Buchia concentrica (Sowerby).

4___Many USGS Mesozoic localities near the Canning 

River, northeast Alaska. Mesozoic Iocs. 24014, 

21028, 25598, and 29882 (Imlay, 1955, p. 79, 

80; Keller and others, 1961, p. 193) from lat 

69°30'45" N. to 69°33' N.; long 146°18' W. to 

146°23' W.; Mesozoic Iocs. 29134-29136 near 

Shublik Island at lat 69°24' N., long 146° 10' W. 

Amoeboceras (Prionodoceras) and Buchia concen trica ( Sowerby).

5__USGS Mesozoic loc. 29133. North side of central 

part of Sadlerochit Mountains, lat 69°4l' N., 

long 144°50' W. Buchia cf. B. concentrica 

(Sowerby).

6__USGS Mesozoic Iocs. 5723, 16921, 16922, 18082, 

18086, and 18089. Area between Slana and 

Nabesna in eastern part of Alaska Range (Moffit 

and Knopf, 1910, p. 29; Moffit, 1938b, p. 32; 

Moffit, 1954, p. 131). Buchia concentrica 

(Sowerby).

7__USGS Mesozoic loc. 5772. Trail along Notch Creek 

northwest of Chisana, eastern part of Alaska 

Range (Moffit and Knopf, 1910, p. 29; Moffit, 

1954, p. 131). Buchia concentrica (Sowerby).

8 .Many localities in the McCarthy C-5 quadrangle, 

Wrangell Mountains (MacKevett, 1969, p. A41, 

A45-49). Buchia concentrica (Sowerby) and 

Amoeboceras (Prinodoceras) from lower part of 

Root Glacier Formation.

9 _Many localities in the Talkeetna Mountains A-l 

quadrangle, Cook Inlet region. Buchia concentrica (Sowerby).

10__Richfield Oil Company Swanson River unit 2 

well, SW^SE^ sec. 22, T. 8 N., R. 9 W., 

Seward Meridian, Kenai Peninsula, Alaska. 

Buchia concentrica (Sowerby) in cores from 

depths of 11,794-11,804 feet. Also, a species of 

Pseudolimea, very common in the Naknek Formation, occurs in cores from depths of 11,846- 

11,856 feet.

11,12____Many localities in Snug Harbor Siltstone Member 

of the Naknek Formation between Iniskin Bay 

and Tuxedni Bay, Cook Inlet region (Martin, 

1926, p. 178-180; Detterman and Hartsock, 1966, 

p. 51). Amoeboceras (loc. 3046 only) and Buchia 

concentrica (Sowerby).
26 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

Locality in 

figure? Description

Late Oxfordian to early Kimmeridgian Continued

13__USGS Mesozoic loc. 28520, 1.22 miles N. 30°E. of 

tip of Ursus Head; Mesozoic loc. 28521, 0.22 mile 

N. 62° E. of tip of Ursus Head. Ursus Cove on 

west side of Cook Inlet. Buchia concentrica 

(Sowerby).

14__USGS Mesozoic loc. 29899. On east tip of westernmost island 1 mile N. 40°E. of mouth of Douglas 

River, lat 59°64'20" N., long 153°44'50" W. 

Iliamna quadrangle, Alaska Peninsula. Buchia 

concentrica (Sowerby) and Perisphinctes (Dichotomosphinctes).

15__USGS Mesozoic loc. 25836. West side of Kaguyak 

Bay, Alaska Peninsula. Buchia concentrica 

( Sowerby).

16__USGS Mesozoic loc. 29248 at western base of Barrier Range north of Fultons Falls, about 1 mile 

S. 12° E. of loc. 29247 and 8 miles north of 

Katmai Bay, Mt. Katmai quadrangle, Alaska 

Peninsula. Buchia concentrica ( Sowerby).

17__USGS Mesozoic loc. 29245. North side of Kashvik 

Bay about 1.7 miles east-northeast of head of 

bay and 3.3 miles S. 27° E. of Atmo Mountain, 

Karluk quadrangle, Alaska Peninsula. Buchia 

concentrica ( Sowerby).

18__USGS Mesozoic Iocs. 3133-3136, 10825, 11333, 12276, 

21353, and many others. Puale Bay area, Karluk 

quadrangle, Alaska Peninsula (Martin, 1926, p. 

212-218). Buchia concentrica (Sowerby).

19__Many localities north and west of Wide Bay, 

Ugashik quadrangle, Alaska Peninsula (Martin, 

1926, p. 212-218). Buchia concentrica (Sowerby.

20__USGS Mesozoic loc. 25696, 25698, 25708, 25710, 

25711, 25713-25715. Chignik Bay area, Chignik 

quadrangle, Alaska Peninsula. Buchia concentrica (Sowerby).

21__USGS Mesozoic loc. M 1213. Knife Peak area west 

of Chignik Bay, Chignik quadrangle, Alaska 

Peninsula (Burk, 1965, p. 160, 176, 219). Buchia 

concentrica (Sowerby).

22__USGS Mesozoic loc. M 1197, M 1224, Staniukovich 

Mountain, Port Moller quadrangle, Alaska Peninsula (Burk, 1965, p. 160, 166, 219). Buchia concentrica (Sowerby).

Locality in 

figure 8 Description

Late Kimmeridgian to early middle Tithonian

1 USGS Mesozoic loc. 29131, headwaters of tributary to 

Thetis Creek, lat 68°42'30" N., long 164°40'30" W. 

Buchia mosquensis (von Buch); Mesozoic loc. 29132, 

south-flowing tributary to Epewik River, lat 

68°38'20" N., long 164°36'00" W., northwest Alaska. 

Buchia cf. B. mosquensis (von Buch).

2 _USGS Mesozoic loc. 22127. Kukpowruk River, lat 

68°42'30" N., long 163°14' W. (Imlay, 1955, p. 78, 

79). Buchia rugosa (Fischer).

3__USGS Mesozoic loc. 22776. Easternmost fork of Driftwood Creek, lat 68°40' N., long 160°26'28" W., northwest Alaska (Imlay, 1955, p. 78, 79). Buchia rugosa 

(Fischer) and B. mosquensis (von Buch).

Locality in 

figure 8 Description

Late Kimmeridgian to early middle Tithonian Continued

4__USGS Mesozoic loc. 23598. Ipnavik River, 2 miles 

south of Memorial Creek, lat 68°23' N., long 157° 15' 

W., northwest Alaska (Imlay, 1955, p. 78, 79). 

Buchia cf. B. mosquensis (von Buch) and B. concentrica (Sowerby).

5__USGS Mesozoic Iocs. 22750, 22751, 22766, 22768, 22769. 

Lupine River from lat 68°49'30" N. to 68°51' N., 

long 148°17'30" W. to 148°22'30" W. (Keller and 

others, 1961, p. 195). Buchia rugosa (Fischer), B. 

mosquensis (von Buch), and B. concentrica 

(Sowerby).

6__USGS Mesozoic loc. 22746. Small divide nearly 1 mile 

east of Nosebleed Creek, lat 68°52' N., long 148°08' 

W., northeast Alaska (Keller and others, 1961, p. 

195). Buchia rugosa (Fischer).

7__USGS Mesozoic loc. 21027, Shaviovik River, main fork 

of most easterly branch, lat 69°22' N., long 146°32' 

W. (Imlay, 1955, p. 79, 80). Buchia rugosa (Fischer) 

and B. mosquensis (von Buch). Mesozoic loc. 24028 

from Kavik River, lat 69°24'45", long 146°37'30" 

W., northeast Alaska. Buchia rugosa (Fischer) and 

B. concentrica (Sowerby).

8__USGS Mesozoic Iocs. 29872, 29897, and 30076. Ridge 

south of Joe Creek, 11.5 miles N. 75° W. of point 

where creek crosses International Boundary, Table 

Mtn. quadrangle, lat 68°58' N., long 146°38' W., 

northeast Alaska. Buchia rugosa (Fischer).

9__USGS Mesozoic loc. 16085. Head of Lost Creek, lat 

62°36' N., long 142°59' w., area between Slana and 

Nebesna, eastern Alaska Range. Buchia rugosa 

(Fischer).

10__Many USGS Mesozoic localities in the McCarthy C5 quadrangle, Wrangell Mountains (MacKevett, 

1969, p. A41, A45-A49). Buchia rugosa (Fischer) 

from upper part of Root Glacier Formation. 

11__USGS Mesozoic Iocs. 3271, 3309, 8851, 10095, 10169, 

27068, 27071-73, 27334, and 27335 from Pybus Bay 

area in southeastern part of Admiralty Island, 

southeast Alaska (Loney, 1964, p. 97). Buchia 

rugosa (Fischer).

12__USGS Mesozoic Iocs. 11401 and 11935 from north end 

of Kupreanoff Island between Hamilton Bay and 

Keku Strait, southeast Alaska (Martin, 1926, p. 

379, 380). Buchia rugosa (Fischer).

13__USGS Mesozoic Iocs. 9528-30 on Gravina Island, 

southeast Alaska. Buchia rugosa (Fischer) and B. 

cf. B. mosquensis (von Buch).

14__Many localities in the Talkeetna Mountains A-l 

quadrangle, Cook Inlet region. Buchia rugosa 

(Fischer) and B. mosquensis (von Buch).

15__USGS Mesozoic Iocs. 20714 and 27092. Near top of 

ridge, 2,800 feet west of Discovery Creek, 2 miles 

S. 69° E. of Mt. Hamilton, and 18.3 miles S. 53° 

W from confluence of Buckstock and Aniak Rivers. 

Coordinates 19.6, 3.00 in Russian Mission quadrangle, Kuskokwim region, southwest Alaska. Buchia 

rugosa (Fischer) and B. mosquensis (von Buch).
FOSSIL OCCURRENCES BY STAGES 27

Locality in 

figure 8 Description

Late Kimmeridgian to early middle Tithonian Continued

16__USGS Mesozoic loc. 24257. Thirty-two miles S. 80°45' 

E. from Kwinhagak and 55 miles N. 58° 25' E. 

from Platinum, Goodnews quadrangle, Kuskokwim 

region, southwest Alaska. Buchia cf. B. rugosa 

(Fischer).

17__USGS Mesozoic Iocs. 24957, 25839, 29250, 29253, M 

5341, M 5345, and M 5348. Cliffs on south side 

of Kamashak Bay extending 2-10 miles west-northwest from the mouth of Douglas River, lat 59°03'45" 

N. to 59°04'30" N., long 153°49'30" W. to 154°02' 

W., Iliamna quadrangle, head of Alaska Peninsula. 

Buchia rugosa (Fischer) and B. mosquensis (von 

Buch).

18 _USGS Mesozoic loc. 24955 from sea cliff on west side 

of mouth of Douglas River, coordinates 19.98-1.32; 

Mesozoic loc. 25832 on westernmost of two offshore 

islands 0.6 mile N. 35° E. of mouth of Douglas 

River; Mesozoic loc. 25833 near mouth of Douglas 

River, coordinates 19.8-0.9, Iliamna quadrangle, 

head of Alaska Peninsula. Buchia rugosa (Fischer) 

and B. mosquensis (von Buch).

19__USGS Mesozoic Iocs. 24956, 29249, 29254 on west 

shore of Kaguyak Bay. Mesozoic loc. 24956 is 1 mile 

north of abandoned village of Kaguyak, coordinates 

0.82, 10.38; Mesozoic loc. 29254 is on small island 

0.7 mile -S. 18° E. of abandoned village, Afognak 

quadrangle, Alaska Peninsula. Buchia mosquensis 

(von Buch) and B. rugosa (Fischer).

20__USGS Mesozoic Iocs. 25276-25278 and M 2076. On 

northeast side of Grosvenor Lake, lat 58°41' N., 

long 155°7'-10' W., Mt. Katmai quadrangle, Alaska 

Peninsula. Buchia rugosa (Fischer) and B. mosquensis (von Buch) range from just below Chisik 

Conglomerate Member of Naknek Formation (loc. 

M 2076) to 530 feet above (loc. 25277).

21__USGS Mesozoic loc. 29247. About 9 miles north of 

Katmai Bay at western base of Barrier Range near 

Fultons Falls and about 7.7 miles N. 54° E. of 

Topographers Peak, Mt. Katmai quadrangle, Alaska 

Peninsula. Buchia mosquensis (von Buch).

22__USGS Mesozoic loc. M 5295. SE1^ sec. 32 (estimated), 

T. 42 S., R. 59 W., about 8.4 miles N. 30° W. of 

mouth of Thompson Creek on Chignik Bay, Chignik 

quadrangle, Alaska Peninsula. Buchia rugosa 

(Fischer) and B. cf. B. mosquensis (von Buch).

23__USGS Mesozoic Iocs. M 1199, M 1244, M 1204 from 

Staniukovich Mountain between Herendeen Bay and 

Port Moller, Alaska Peninsula (Burk, 1965, p. 31, 

160, 219). Buchia mosquensis (von Buch) and B. 

rugosa (Fischer).

24__USGS Mesozoic loc. M 1234 from Lake Creek area 

southwest of Herendeen Bay, Alaska Peninsula 

(Burk, 1965, p. 31, 160, 219). Buchia rugosa 

(Fischer) ?

25__USGS Mesozoic loc. 29898. Black Hills area about 40 

miles west of Herendeen Bay on north side of 

Alaska Peninsula. Buchia rugosa (Fischer).

Locality in 

figure 9 Description

Late middle to late Tithonian

1__USGS Mesozoic loc. 26390. Middle fork of Okpikruak 

River, lat 68°32'30" N., long 153°30'30" W., northcentral Alaska. Buchia cf. B. fischeriana 

(d'Orbigny).

2__USGS Mesozoic loc. M2531. Kemik Creek, 3.6 miles 

upstream from junction with Shaviovik River, 

Sagavanirtok quadrangle, lat 69°27' N., long 

147°08' W., northeast Alaska. Buchia unschensis 

(Pavlow).

3__USGS Mesozoic Iocs. 30078 and 30079. On Joe Creek, 

10.6-11 miles west of Canadian border and 300 

feet or less higher stratigraphically than Mesozoic 

loc. 30076, which has furnished Buchia rugosa 

(Fischer). Table Mountains quadrangle, northeast 

Alaska. Buchia unschensis (Pavlow).

4____USGS Mesozoic loc. 18349. Jacksina River, 1 mile 

southwest of mouth, just south of Nebesna, eastern 

part of Alaska Range, eastern Alaska (Moffit, 1943, 

pi. 2; 1954, p. 131). Buchia cf. B. fischeriana 

(d'Orbigny).

5__USGS Mesozoic loc. 8811, near mouth of Gold Run 

Creek, a southern tributary of Glacier Creek (Capps, 

1916, p. 52, fig. 9 on p. 100) ; Mesozoic loc. M5377, 

south side of Bonanza Creek, 5.4 miles N. 57° E. 

of junction with Chathenda Creek in SW 1^ sec. 15, 

T. 4 N., R. 20 E.; Mesozoic loc. M5386, upper part 

of Chathenda Creek, 6.5 miles N. 75° E. of outlet 

of Little Beaver Lake at elevation of 5,300 ft.; 

Mesozoic loc. M5425, Coarse Money Creek, 1 mile 

upstream from its junction with Bonanza Creek, 

SWH sec. 17, T. 4 N., R. 20 E.; Mesozoic loc. M5563, 

south side of Chathenda Creek, 5.2 miles N. 46° E. 

of outlet of Little Beaver Lake, SE^ sec. 22, T. 4 

N., R. 20 E.; Mesozoic loc. M5564, Chathenda Creek, 

5.3 miles N. 46° E. of outlet of Little Beaver Lake. 

All localities in central and west-central part of the 

Nabesna A-2 quadrangle in eastern part of Alaska 

Range. Buchia fischeriana (d'Orbigny).

6__USGS Mesozoic loc. M1215. Northeast Creek area 

north of Amber Bay, Alaska Peninsula (Burk, 1965, 

p. 160, 178, 220). Buchia piochii (Gabb).

7__USGS Mesozoic loc. M 5297. Ten miles N. 76° W. of 

mouth of Thompson Creek on Chignik Bay, northcentral part of sec. 12 near sec. 1 (estimated), T. 

43 S., R. 60 W., Chignik quadrangle, Alaska Peninsula (Burk, 1965, p. 160, 176, 219). Buchia piochii 

(Gabb).

8__USGS Mesozoic loc. M 1211. Granville Portage area 

near Ivanoff Bay, Alaska Peninsula (Burk, 1965, 

p. 160, 170, 219). Buchia piochii (Gabb).

9__USGS Mesozoic loc. M 1238. Staniukovich Mountain 

between Herendeen Bay and Port Moller, Alaska 

Peninsula (Burk, 1965, p. 160, 166, 219). Buchia 

piochii (Gabb).

10__USGS Mesozoic loc. M 1236. Lake Creek area west of 

Herendeen Bay, Alaska Peninsula (Burk, 1965, p. 

160, 162, 219). Buchia piochii (Gabb).
28 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

REFERENCES

Arkell, W. J., 1956, Jurassic geology of the world: London, 

Oliver & Boyd, 806 p., 46 pis., 102 figs.

Atwood, W. W., 1911, Geology and mineral resources of parts 

of the Alaska Peninsula: U.S. Geol. Survey Bull. 467, 

137 p.

Bergquist, H. R., 1966, Micropaleontology of the Mesozoic 

rocks of northern Alaska: U.S. Geol. Survey Prof. Paper 

302-D, p. 93-227.

Bishop, W. F., 1967, Age of the pre-Smackover formations, 

north Louisiana and south Arkansas: Am. Assoc. Petroleum Geologists Bull., v. 51. no. 2, p. 244-250, 18 figs.

Brabb, E. E., 1969, Six new Paleozoic and Mesozoic formations in east-central Alaska: U.S. Geol. Survey Bull. 

1274-1, p. 1-26.

 1970, Preliminary geologic map of the Black River 

quadrangle, east-central Alaska: U.S. Geol. Survey Misc. 

Geol. Inv. Map. 1-601.

Brabb, E. E., and Churkin, Michael, Jr., 1969, Geologic map 

of the Charley River quadrangle, east-central Alaska: 

U.S. Geol. Survey Misc. Geol. Inv. Map 1-573.

Brew, D. A., Loney, R. A., and Muffler, L. J. P., 1966, Tectonic history of southeastern Alaska: Canadian Inst. 

Mining and Metallurgy Spec. Vol. 8, p. 149-170.

Brosge, W. P., and Reiser, H. N., 1964, Geologic map and 

section of the Chandalar quadrangle, Alaska: U.S. Geol. 

Survey Misc. Geol. Inv. Map 1-375.

 1969, Preliminary geologic map of the Coleen quadrangle, Alaska: U.S. Geol. Survey open-file report, 

scale 1:250,000.

Brosge, W. P., and Tailleur, I. L., 1970, Depositional history 

of northern Alaska, in Adkison, W. L., and Brosge, M. 

M., eds., Geological seminar on the North Slope of 

Alaska, Palo Alto, Calif., 1970, Proc.: Los Angeles, Am. 

Assoc. Petroleum Geologists, Pacific Sec., p. D1-D18.

Burckhardt, Carlos, 1927, Cefalopodos del Jurasico medio 

de Oaxaca y Guerrero: Mexico Inst. Geol. Bol. 47, 108 

p., 34 pis.

 1930-31, fitude synthetique sur le Mesozoique mexicain: Schweizer. Paleont. Gesell. Abh., v. 49, pi. 1-123;

v. 50, p. 123-280, 65 figs. 

Burk, C. A., 1965, Geology of the Alaska Peninsula Island

arc and continental margin: Geol. Soc. America Mem.

99, 250 p., 8 pis., 28 figs., 1 geol. map, 1 tectonic map. 

Cady, W. M., Wallace, R. E., Hoare, J. M., and Webber, E.

J., 1955, The central Kuskokwim region, Alaska: U.S.

Geol. Survey Prof. Paper 268, 132 p., 9 pis., 38 figs. 

Callomon, J. H., 1959, The ammonite zones of the Middle

Jurassic beds of East Greenland: Geol. Mag., v. 96,

no. 6, p. 505-513, pis. 17, 18. 

Campbell, R. H., 1967, Areal geology in the vicinity of the

Chariot site, Lisbourne Peninsula, northwestern Alaska:

U.S. Geol. Survey Prof. Paper 395, 71 p. 

Capps, S. R., 1916, The Chisana-White River district, Alaska:

U.S. Geol. Survey Bull. 630, 130 p., maps.

 1923, The Cold Bay district [Alaska]: U.S. Geol. 

Survey Bull. 739-C, p. 77-116.

1934, Notes on the geology of the Alaska Peninsula

and Aleutian Islands: U.S. Geol. Survey Bull. 857-D, p. 

141-153, 1 pi.

Carey, S. W., 1958, The tectonic approach to continental 

drift, in Carey, S. W., Continental drift; a symposium: 

Hobart, Tasmania, Tasmania Univ. Geology Dept., p. 

177-355.

Chapman, R. M., Detterman, R. L., and Mangus, M. D.,

1964, Geology of the Killik-Etivluk Rivers region,

Alaska: U.S. Geol. Survey Prof. Paper 303-F, p. 325-

407. 

Chapman, R. M., and Sable, E. G., 1960, Geology of the

Utukok-Corwin region, northwestern Alaska: U.S. Geol.

Survey Prof. Paper 303-C, p. 47-167. 

Collins, F. R., 1958, Test wells, Topagoruk area, Alaska:

U.S. Geol. Survey Prof. Paper 305-D, p. 265-316, pis.

17-18, figs. 14-17.

 1961, Core tests and test wells Barrow area, Alaska: 

U.S. Geol. Survey Prof. Paper 305-K, p. 569-643.

Detterman, R. L., 1963, Revised stratigraphic nomenclature 

and age of the Tuxedni Group in the Cook Inlet region, 

Alaska: U.S. Geol. Survey Prof. Paper 475-C, p. C30- 

C34.

 1973, Mesozoic sequence in Arctic Alaska, in International Arctic Symposium, 2d, Proc.: Am. Assoc. Petroleum Geologists, in press.

Detterman, R. L., and Hartsock, J. K., 1966, Geology of 

the Iniskin-Tuxedni region, Alaska: U.S. Geol. Survey 

Prof. Paper 512, 78 p., 6 pis., 7 figs.

Detterman, R. L., and Reed, B. L., 1964, Preliminary map 

of the geology of the Iliamna quadrangle, Alaska: U.S. 

Geol. Survey Misc. Geol. Inv. Map 1-407.

Detterman, R. L., Reed, B. L., and Lanphere, M. A., 1965, 

Jurassic plutonism in the Cook Inlet region, Alaska: 

U.S. Geol. Survey Prof. Paper 525-D, p. D16-D21.

Erben, H. K., 1956, El Jurasico Inferior de Mexico y sus 

amonitas: Mexico City, Internt. Geol. Gong., 20th, 1956, 

393 p., 41 pis., 5 maps.

 1957, New biostratigraphic correlations in the 

Jurassic of eastern and south-central Mexico, in El 

Mesozoico del Hemisferio Occidental y sus correlations 

mundiales: Internat. Geol. Gong., 20th, Mexico City, 

1956, [Trabajos], sec. 2, p. 43-52.

Frebold, Hans, 1961, The Jurassic faunas of the Canadian 

Arctic Middle and Upper Jurassic ammonites: Canada 

Geol. Survey Bull. 74, 43 p., 21 pis., 3 figs.

 1964a, Illustrations of Canadian Jurassic fossils 

Jurassic of western and Arctic Canada: Canada Geol. 

Survey Paper 63-4, 51 pis.

1964b, Outline of the Jurassic system in Canada:

Colloque du Jurassique, Luxembourg 1962, Comptes 

Rendus et Mem., p. 479-483.

Frebold, Hans, Mountjoy, E. W., and Reed, R. A., 1959, 

The Oxfordian beds of the Jurassic Fernie group, Alberta and British Columbia: Canada Geol. Survey Bull. 

53, 47 p., 12 pis., 6 figs.

Frebold, Hans, Mountjoy, E. W., and Tempelman-Kluit, D. 

J., 1967, New occurrences of Jurassic rocks and fossils 

in central and northern Yukon Territory: Canada Geol. 

Survey Paper 67-12, 35 p., 3 pis., 2 figs.

Frebold, Hans, and Tipper, H. W., 1967, Middle Callovian 

sedimentary rocks and guide ammonites from southwestern British Columbia: Canada Geol. Survey Paper 

67-21, 29 p., 3 pis., 2 text-figs.

 1970, Status of the Jurassic in the Canadian 

Cordillera of British Columbia, Alberta, and southern 

Yukon: Canadian Jour. Earth Sci., v. 7, no. 1, p. 1-21, 

9 figs.

Gates, G. 0., Grantz, Arthur, and Patton, W. W., Jr., 1968, 

Geology and natural gas and oil resources of Alaska 

Part 1, Natural gases in rocks of Cenozoic age: Am. 

Assoc. Petroleum Geologists Mem. 9, v. 1, p. 3-48.
REFERENCES 29

Gates, G. 0., and Gryc, George, 1963, Structure and tectonic 

history of Alaska, in Backbone of the Americas: Am. 

Assoc. Petroleum Geologists Mem. 2, p. 264-277.

Grantz, Arthur, 1960a, Geologic map of Talkeetna Mountains (A-2) quadrangle, Alaska, and the contiguous 

area to north and northwest: U.S. Geol. Survey Misc. 

Geol. Inv. Map 1-313.

 1960b, Geologic map of Talkeetna Mountains (A-l) 

quadrangle, and the south third of Talkeetna Mountains 

(B-l) quadrangle, Alaska: U.S. Geol. Survey Misc. 

Geol. Inv. Map 1-314.

 1961a, Geologic map and cross sections of the 

Anchorage (D-2) quadrangle and northeasternmost part 

of the Anchorage (D-3) quadrangle, Alaska: U.S. Geol. 

Survey Misc. Geol. Inv. Map 1-342.

 1961b, Geologic map of the north two-thirds of the 

Anchorage (D-l) quadrangle, Alaska: U.S. Geol. Survey Misc. Geol. Inv. Map 1-343.

1966, Strike-slip faults in Alaska: U.S. Geol. Survey

open-file report, 82 p., 8 figs. 

Grantz, Arthur, Jones, D. L., and Lanphere, M. A., 1966,

Stratigraphy, paleontology, and isotopic ages of upper

Mesozoic rocks in the southwestern Wrangell Mountains,

Alaska: U.S. Geol. Survey Prof. Paper 550-C, p. C39-

C47. 

Grantz, Arthur, Thomas, Herman, Stern, T. W., and Sheffey,

N. B., 1963, Potassium-argon and lead-alpha ages for

stratigraphically bracketed plutonic rocks in the

Talkeetna Mountains, Alaska: U.S. Geol. Survey Prof.

Paper 475-B, p. B56-B59. 

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

Geology of the Arctic slope of Alaska: U.S. Geol. Survey

Oil and Gas Inv., Map OM-126, scale 1:1,000,000, 3

sheets, text. 

Gryc, George, and Lathram, E. H., 1954, Preliminary report

on the geology of the Sagavanirktok River area, 1946;

U.S. Geol. Survey open-file report, 5 p. 

Gryc, George, and Mangus, M. D., 1954, Preliminary report

on the stratigraphy and structure of the area of the

Shaviovik and Canning Rivers, Alaska, 1947: U.S. Geol.

Survey open-file report, 7 p., 1 pi. 

Hallam, Anthony, 1965, Observations on marine Lower

Jurassic stratigraphy of North America, with special

reference to the United States: Am. Assoc. Petroleum

Geologists Bull., v. 49, no. 9, 1485-1501, 5 figs. 

Hamilton, W. B., 1969, Continental drift in the Arctic [abs.]:

Geol. Soc. America Spec. Paper 121, p. 510. 

Hoare, J. M., 1961, Geology and tectonic setting of lower

Kuskokwim-Bristol Bay region, Alaska: Am. Assoc.

Petroleum Geologists Bull., v. 45, no. 5, p. 594-611. 

Hoare, J. M., and Coonrad, W. L., 1959a, Geology of the

Bethel quadrangle, Alaska: U.S. Geol. Survey Misc.

Geol. Inv. Map 1-285.

 1959a, Geology of the Russian Mission quadrangle, 

Alaska: U.S. Geol. Survey Misc. Geol. Inv. Map 1-292.

 1961a, Geologic map of the Hagemeister Island quadrangle, Alaska: U.S. Geol. Survey Misc. Geol. Inv. Map 

1-321.

1961b, Geologic map of the Goodnews quadrangle,

Alaska: U.S. Geol. Survey Misc. Geol. Inv. Map 1-339. 

Howarth, M. K., 1958, A monograph of the ammonites of the 

Liassic family Amaltheidae in Britain: London, 

Palaeontograph. Soc., pt. 1, p. i-xiv, 1-26, pis. 1-4 (v. 

Ill); pt. 2, p. xv-xxxvii, 27-53, pis. 5-10 (v. 112).

Imlay, R. W., 1943, Jurassic formations of Gulf region: Am. 

Assoc. Petroleum Geologists Bull., v. 27, no. 11, p. 1407- 

1533, 14 figs.

 1952, Correlation of the Jurassic formations of North 

America, exclusive of Canada: Geol. Soc. America Bull., 

v. 63, no. 9, p. 953-992, 2 correlation charts.

 1953a, Callovian (Jurassic) ammonites from the 

United States and Alaska Part 1. Western Interior 

United States: U.S. Geol. Survey Prof. Paper 249-A, 

p. 1-40, pis. 1-24, figs. 1, 2.

 1953b, Callovian (Jurassic) ammonites from the 

United States and Alaska Part 2. Alaska Peninsula 

and Cook Inlet region: U.S. Geol. Survey Prof. Paper 

249-B, p. 41-108, pis. 25-55, figs. 3-9.

 1955, Characteristic Jurassic mollusks from northern 

Alaska: U.S. Geol. Survey Prof. Paper 274-D, p. 69-96, 

pis. 8-13, fig. 20.

 1959, Succession and speciation of the pelecypod 

Aucella: U.S. Geol. Survey Prof. Paper 314-G, p. 155- 

169.

 1961a, New genera and subgenera of Jurassic 

(Bajocian) ammonites from Alaska: Jour. Paleontology, 

v. 35, no. 3, p. 467-474.

 1961b, Late Jurassic ammonites from the western 

Sierra Nevada, California: U.S. Geol. Survey Prof. 

Paper 374-D, p. 1-30, 6 pis., 4 figs.

 1962a, Jurassic (Bathonian or early Callovian) ammonites from Alaska and Montana: U.S. Geol. Survey 

Prof. Paper 374-C, 32 p.

 1962b, Late Bajocian ammonites from the Cook Inlet 

region, Alaska: U.S. Geol. Survey Prof. Paper 418-A, 

p. 1-15, pis. 1-5, figs. 1-4.

 1964a, Upper Jurassic mollusks from eastern Oregon 

and western Idaho: U.S. Geol. Survey Prof. Paper 483- 

D, p. 1-21, 4 pis., 3 figs.

 1964b, Middle Bajocian ammonites from the Cook 

Inlet region, Alaska: U.S. Geol. Survey Prof. Paper 

418-B, p. 1-61, pis. 1-29, 5 figs.

 1965, Jurassic marine faunal differentiation in North 

America: Jour. Paleontology, v. 39, no. 5, p. 1023-1038, 

6 figs.

 1967, The Mesozoic pelecypods Otapiria Marwick and 

Lupherella Imlay, new genus, in the United States: U.S. 

Geol. Survey Prof. Paper 573-B, p. 1-11, 2 pis., 2 figs.

 1968, Lower Jurassic (Pliensbachian and Toarcian) 

ammonites from eastern Oregon and California: U.S. 

Geol. Survey Prof. Paper 593-C, p. 1-51, 9 pis., 8 figs. 

1970, Jurassic paleogeography of Alaska [abs.]: Am.

Assoc. Petroleum Geologists Bull., v. 54, no. 12, p. 2487.

Imlay, R. W., and Jones, D. L., 1970, Ammonites from the 

Buchia zones in northwestern California and southwestern Oregon: U.S. Geol. Survey Prof. Paper 647-B, p. 

B1-B59, 15 pis., 8 figs.

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

the Cretaceous formations of Greenland and Alaska: 

Geol. Soc. America Bull., v. 65, no. 3, p. 223-246.

Jeletzky, J. A., 1958, Uppermost Jurassic and Cretaceous 

rocks of Aklavik Range, northeastern Richardson Mountains, Northwest Territories: Canada Geol. Survey Paper 

58-2, 84 p., geol. sketch map, correlation chart.

 1960, Uppermost Jurassic and Cretaceous rocks, east 

flank of Richardson Mountains between Stony Creek 

and lower Donna River, Northwest Territories, 106 M 

and 107B (parts of) : Canada Geol. Survey Paper 59-14 

31 p., geol. sketch maps, correlation chart.
30 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

 1962, Pre-Cretaceous Richardson Mountains trough 

Its place in the tectonic framework of Arctic Canada and 

its bearing on some geosynclinal concepts: Royal Soc. 

Canada Trans., 3d ser., v. 56, sec. 3, pt. 1, p. 55-84.

 1966, Upper Volgian (latest Jurassic) ammonites 

and Buchias of Arctic Canada: Canada Geol. Survey 

Bull. 128, 51 p., 8 pis., 2 figs.

1967, Jurassic and (?) Triassic rocks of the eastern

slope of Richardson Mountains, northwestern District 

of Mackenzie: Canada Geol. Survey Paper 66-50, 171 

p., 9 pis., 3 figs.

Jones, D. L., and Grantz, Arthur, 1964, Stratigraphic and 

structural significance of Cretaceous fossils from 

Tiglukpuk Formation, northern Alaska: Am. Assoc. 

Petroleum Geologists Bull., v. 48, no. 9, p. 1462-1474, 

3 pis., 4 figs.

Juhle, R. W., 1955, Iliamna Volcano and its basement: U.S. 

Geol. Survey open-file report, 74 p., 38 pis.

Keller, A. S., Morris, R. H., and Detterman, R. L., 1961, 

Geology of the Shaviovik and Saganvanirktok Rivers 

region, Alaska: U.S. Geol. Survey Prof. Paper 303-D, 

p. 169-222, pis. 21-26, figs. 26-32.

Keller, A. S., and Reiser, H. N., 1959, Geology of the 

Mount Katmai area, Alaska: U.S. Geol. Survey Bull. 

1058-G, p. 261-298, illus.

Kellum, L. B., 1945, Jurassic stratigraphy of Alaska and 

petroleum exploration in northwest America: New York 

Acad. Sci. Trans., ser. 2, v. 7, no. 8, p. 201-209.

Kirschner, C. E., and Lyon, C. A., 1973, Stratigraphy and 

tectonic development of Cook Inlet petroleum province, 

in International Arctic Symposium, 2d, Proc.: Am. Assoc. 

Petroleum Geologists, in press.

Kirschner, C. E., and Minard, D. L., 1949, Geology of the 

Iniskin Peninsula, Alaska: U.S. Geol. Survey Oil and 

Gas Inv. Prelim. Map OM-95.

Knowlton, F. H., 1914, The Jurassic flora of Cape Lisburne, 

Alaska: U.S. Geol. Survey Prof. Paper 85-D, p. 39-64, 

illus.

Lathram, E. H., 1965, Preliminary geologic map of northern 

Alaska: U.S. Geol. Survey open-file map, 2 sheets, 

scale 1:1,000,000.

Lathram, E. H., Loney, R. A., Berg, H. C., and Pomeroy, 

J. S., 1960, Progress map of the geology of Admiralty 

Island, Alaska: U.S. Geol. Survey Misc. Geol. Inv. 

Map 1-323.

Leffingwell, E. de K., 1919, The Canning River region, 

northern Alaska: U.S. Geol. Survey Prof. Paper 109, 

251 p.

Loeblich, H. N., 1954, Summary of microfossil investigations, April 1948 to April 1949, with special reference 

to the Barrow and Simpson area, 1949: U.S. Geol. Survey open-file report, 83 p., 2 pis., 1 fig.

Loney, R. A., 1964, Stratigraphy and petrography of the 

Pybus-Gambier area, Admiralty Island, Alaska: U.S. 

Geol. Survey Bull. 1178, 103 p., 2 pis., 33 figs.

MacKevett, E. M., Jr., 1963, Preliminary geologic map of 

the McCarthy C-5 quadrangle, Alaska. U.S. Geol. Survey Misc. Geol. Inv. Map 1-406.

 1965a, Preliminary geologic map of the McCarthy B5 quadrangle, Alaska: U.S. Geol. Survey Misc. Geol. 

Inv. Map 1-438.

 1965b, Preliminary geologic map of the McCarthy 

C-6 quadrangle, Alaska: U.S. Geol. Survey Misc. Geol. 

Inv. Map 1-444.

 1969, Three newly named Jurassic formations in the 

McCarthy C-5 quadrangle, Alaska: U.S. Geol. Survey 

Bull. 1274-A, p. 35-49, figs. 3-8.

 1970a, Geologic map of the McCarthy C-4 quadrangle, 

Alaska: U.S. Geol. Survey Geol. Quad. Map GQ-844.

 1970b, Geologic map of the McCarthy C-5 quadrangle, 

Alaska: U.S. Geol. Survey Geol. Quad. Map GQ-899. 

1971, Stratigraphy and general geology of the

McCarthy C-5 quadrangle, Alaska: U.S. Geol. Survey

Bull. 1323, 35 p. 

Maddren, A. G., 1912, Geologic investigations along the

Canada-Alaska boundary: U.S. Geol. Survey Bull. 520,

p. 297-314. 

Maddren, A. G., and Harrington, G. L., 1914, [Geology on]

Topographic maps 141st Meridian, Porcupine River to

Arctic Coast: Washington, D.C., Internat. Boundary

Comm. 

Mangus, M. D., Detterman, R. L., Lachenbruch, M. C., Jr.,

Lachenbruch, A. H., 1954, Stratigraphy and structure

of the Etivluk and Kuna Rivers area, Alaska, 1950: U.S.

Geol. Survey open-file report, 15 p., 3 pis., 1 fig. 

Martin, G. C., 1905, The petroleum fields of the Pacific

coast of Alaska, with an account of the Bering River

coal deposits: U.S. Geol. Survey Bull. 250, 64 p.

 1921, Preliminary report on petroleum in Alaska: 

U.S. Geol. Survey Bull. 719, 83 p., 11 pis., 6 figs.

 1925, The outlook for petroleum near Chignik 

[Alaska]: U.S. Geol. Survey Bull. 773-D, p. 209-213. 

1926, The Mesozoic stratigraphy of Alaska: U.S.

Geol. Survey Bull. 776, 493 p., 13 figs. 

Martin, G. C., and Katz, F. J., 1912, A geologic reconnaissance of the Iliamna region, Alaska: U.S. Geol. Survey

Bull. 485, 138 p. 

Mather, K. F., 1925, Mineral resources of the Kamishak

Bay region [Alaska]: U.S. Geol. Survey Bull. 773-D,

p. 159-181, illus. 

Mertie, J. B., 1929, Preliminary report on the Sheenjek

River district [Alaska]: U.S. Geol. Survey Bull. 797, p.

99-123.

 1930, The Chandalar-Sheenjek district [Alaska]: U.S.

Geol. Survey Bull. 810-B, p. 87-139, 2 pis., 2 figs. 

Miller, D. J., Payne, T. G., and Gryc, George, 1959, Geology

of possible petroleum provinces in Alaska: U.S. Geol.

Survey Bull. 1094, 131 p. 

Moffit, F. H., 1922a, Geology of the vicinity of Tuxedni Bay,

Cook Inlet, Alaska: U.S. Geol. Survey Bull. 722-D, p.

141-147, illus.

 1922b, The Iniskin Bay district [Alaska]: U.S. Geol. 

Survey Bull. 739-C, p. 117-132, 1 pi.

 1927, The Iniskin-Chinitna Peninsula and the Snug 

Harbor district, Alaska: U.S. Geol. Survey Bull. 789, 

71 p., 11 pis., 1 fig.

 1938a, Geology of the Chitina Valley and adjacent 

area, Alaska: U.S. Geol. Survey Bull. 894, 137 p., 16 

pis., 1 fig.

 1938b, Geology of the Slana-Tok district, Alaska: 

U.S. Geol. Survey Bull. 904, 54 p., 4 pis., 4 figs.

 1943, Geology of the Nutzotin Mountains, Alaska: 

U.S. Geol. Survey Bull. 933-B, p. 103-299, pis. 2-12, text/- 

figs. 4-7.

 1954, Geology of the eastern part of the Alaska 

Range and adjacent area: U.S. Geol. Survey Bull. 989- 

D, p. 65-218, pis. 6, 7, figs. 18-40.
REFERENCES 31

Moffit, F. H., and Knopf, Adolph, 1910, Mineral resources 

of the Nabesna-White River district, Alaska; with a 

section on the Quaternary, by S. R. Capps: U.S. Geol. 

Survey Bull. 417, 64 p.

Muller, S. W., and Ferguson, H. G., 1939, Mesozoic stratigraphy of the Hawthorne and Tonopah quadrangles, 

Nevada: Geol. Soc. America Bull., v. 50, no. 10, p. 1573- 

1624, 6 pis., 4 figs.

Paige, Sidney, 1906, The Herendeen Bay coal field: U.S. 

Geol. Survey Bull. 284, p. 101-108.

Paige, Sidney, and Knopf, Adolph, 1907, Geologic reconnaissance in the Matanuska and Talkeetna basins, 

Alaska: U.S. Geol. Survey Bull. 327, 71 p.

Patton, W. W., Jr., 1956, New formation of Jurassic age, 

in Gryc, George, and others, Mesozoic sequence in Colville River region, northern Alaska: Am. Assoc. Petroleum Geologists Bull., v. 40, no. 2, p. 213-218.

Patton, W. W., Jr., and Grantz, Arthur, 1962, Tectonic 

implications of some new Mesozoic stratigraphic data 

on Alaska tabs.]: Am. Assoc. Petroleum Geologists Bull., 

v. 46, no. 2, p. 274-275.

Patton, W. W., Jr., and Keller, A. S., 1954, Stratigraphy and 

structure of the upper Siksikpuk-Nanushuk Rivers area, 

Alaska, 1951: U.S. Geol. Survey open-file report, 20 p., 

4 pis., 3 figs.

Patton, W. W., Jr., and Tailleur, I. L., 1954, Stratigraphy 

and structure of the Okpikruak and Kiruktagiak Rivers 

area, Alaska, 1950: U.S. Geol. Survey open-file report, 

17 p., 3 pis., 1 fig.

 1964, Geology of the Killik-Itkillik region, Alaska: 

U.S. Geol. Survey Prof. Paper 303-G, p. 409-500, pis. 

50-51, figs. 66-91.

Payne, T. G., 1955, (Compiler), Mesozoic and Cenozoic 

tectonic elements of Alaska: U.S. Geol. Survey Misc. 

Geol. Inv. Map 1-84.

Payne, T. G., and others, 1951, Geology of the Arctic slope 

of Alaska: U.S. Geol. Survey Oil and Gas Inv. Map OM126, scale 1:1,000,000, 3 sheets, text.

Reed, B. L., 1968, Geology of the Lake Peters area, northeastern Brooks Range, Alaska: U.S. Geol. Survey Bull. 

1236, 132 p.

Reed, B. L., and Lanphere, M. A., 1969, Age and chemistry 

of Mesozoic and Tertiary plutonic rocks in south-central 

Alaska: Geol. Soc. America Bull., v. 80, no. 1, p. 23-44.

Reiser, H. N., Lanphere, M. A., and Brosge, W. P., 1965, 

Jurassic age of mafic igneous complex, Christian quadrangle, Alaska: U.S. Geol. Survey Prof. Paper 525-C, 

p. C68-C71.

Reiser, H. N., and Tailleur, I. L., 1969, compilers, Preliminary 

geologic map of Mt. Michelson quadrangle, Alaska: U.S. 

Geol. Survey open-file map, scale 1:200,000.

Reiser, H. N., and others, 1970, Progress map, geology of 

the Sadlerochit and Shublik Mountains, Mt. Michelson 

C-l, C-2, C-3, and C-4 quadrangles, Alaska: U.S. Geol. 

Survey open-file report, 5 sheets (4 maps and explanation) .

Richter, D. H., 1971, Reconnaissance geologic map and section of the Nabesna B-4 quadrangle, Alaska: U.S. Geol. 

Survey Misc. Geol. Inv. Map 1-656.

Richter, D. H., and Jones, D. L., 1970, Structure and stratigraphy of the Eastern Alaska Range, Alaska tabs.]: Am. 

Assoc. Petroleum Geologists Bull., v. 54, no. 12, p. 2502.

Rickwood, F. K., 1970, The Prudhoe Bay field, in Adkison, 

W. L., and Brosge, M. M., eds., Geological seminar on

the North Slope of Alaska, Palo Alto, Calif., 1970, Proc.,: 

Los Angeles, Am. Assoc. Petroleum Geologists, Pacific 

Sec., p. L1-L11.

Robinson, F. M., 1959, Test wells, Simpson area, Alaska: 

U.S. Geol. Survey Prof. Paper 305-J, p. 523-568.

Sable, E. G., 1965, Geology of the Romanzof Mountains, 

Brooks Range, northeastern Alaska: U.S. Geol. Survey 

open-file report, 218 p., 7 pis., 23 figs.

Sable, E. G., and Mangus, M. D., 1954, Stratigraphy and 

structure of the upper Utukok-Kokolik Rivers area, 

Alaska, 1951; U.S. Geol. Survey open-file report, 19 

p., 2 pis.

St. Amand, Pierre, 1957, Geological and geophysical synthesis of the tectonics of portions of British Columbia, 

the Yukon Territory, and Alaska: Geol. Soc. America 

Bull., v. 68, no. 10, p. 1343-1370.

Smith, P. S., 1917, The Lake dark-central Kuskokwim 

region, Alaska: U.S. Geol. Survey Bull. 655, 162 p.

 1939, Areal geology of Alaska: U.S. Geol. Survey 

Prof. Paper 192, 100 p.

Smith, P. S., and Mertie, J. B., Jr., 1930, Geology and mineral resources of northwestern Alaska: U.S. Geol. Survey Bull. 815, 351 p., 34 pis., 22 figs.

Smith, W. R., 1925, The Cold Bay-Katmai district [Alaska]: 

U.S. Geol. Survey Bull. 773-D, p. 183-207, map.

Smith, W. R., and Baker, A. A., 1924, The Cold Bay-Chignik 

district, Alaska: U.S. Geol. Survey Bull. 755-D, p. 151- 

218, illus.

Spurr, J. E., 1900, A reconnaissance in southwestern Alaska 

in 1898: U.S. Geol. Survey Ann. Rept. 20, pt. 7, p. SI264, illus.

Stanton, T. W., and Martin, G. C., 1905, Mesozoic section 

on Cook Inlet and Alaska Peninsula: Geol. Soc. America 

Bull., v. 16, p. 391-410.

Stone, R. W., 1965, Coal resources of southwestern Alaska: 

U.S. Geol. Survey Bull. 259, p. 151-171, illus.

Tailleur, I. L., 1964, Rich oil shale from northern Alaska: 

U.S. Geol. Survey Prof. Paper 475-D, p. D131-D133.

 1969, Speculations on North Slope geology: Oil and 

Gas Jour., v. 67, no. 38, p. 215-220, 225-226; no. 39, 

p. 128-130.

Tailleur, I. L., and Brosge, W. P., 1970, Tectonic history of 

northern Alaska, in Adkison, W. L., and Brosge, M. M., 

eds., Geological seminar on the North Slope of Alaska, 

Palo Alto, Calif., 1970, Proc.: Los Angeles, Am. Assoc. 

Petroleum Geologists, Pacific Sec., p. E1-E19.

Tailleur, I. L., and Kent, B. H., 1954, Stratigraphy and 

structure of the Southern Foothills section between the 

Etivluk and Kiligwa Rivers, Alaska, 1951: U.S. Geol. 

Survey open-file report, 26 p., 4 pis., 2 figs.

Tailleur, I. L., Kent, B. H., Jr., and Reiser, H. N., 1966, 

Outcrop geologic maps of the Nuka-Etivluk region, 

northern Alaska: U.S. Geol. Survey open-file report, 

7 sheets (map, scale 1:63,360, and explanation).

Tappan, Helen, 1951, Micropaleontology, in Payne, T. G., 

and others, Geology of the Arctic slope of Alaska: 

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

1:1,000,000, 3 sheets, text.

1955, Foraminifera from the Arctic slope of Alaska 

Pt. 2, Jurassic Foraminifera: U.S. Geol. Survey Prof. 

Paper 236-B, p. 21-90, pis. 6-28, figs. 3-9. 

Viniegra 0., Francisco, 1971, Age and evolution of salt 

basins of southeastern Mexico: Am. Assoc. Petroleum 

Geologists Bull., v. 55, no. 3, p. 478-494,10 figs.
32 JURASSIC PALEOBIOGEOGRAPHY OF ALASKA

Wahrhaftig, Clyde, 1965, Physiographic divisions of Alaska: 

U.S. Geol. Survey Prof. Paper 482, 52 p.

Westermann, G. E. G., 1964, The ammonite fauna of the 

Kialagvik Formation at Wide Bay, Alaska Peninsula. 

Part 1, Lower Bajocian (Aalenian) : Bulls. Am. Paleontology, v. 47, no. 216, p. 327-503, pis. 44-76, 37 figs.

 1969, The ammonite fauna of the Kialagvik Formation at Wide Bay, Alaska Peninsula Part II, Sonninia 

sowerbyi zone (Bajocian): Bulls. Am. Paleontology, v. 

57, no. 255, 226 p., pis. 1-47, 56 figs.

Whittington, C. L., and Sable, E. G., 1954, Preliminary 

geologic report of Sadlerochit River area, 1948: U.S. 

Geol. Survey open-file report, 18 p., 1 pi.
INDEX

[Italic page numbers indicia te major references]

Page

Acknowledgments ___._ . _ 3 

Admiralty Island _----- __ _ 20

Alaska Peninsula __ 2,8,9,14,16,17,18,20 

Alaska Range ._ . . .. 9,20 

Aleutian Range batholith -- 16 

Alinchak Bay ----- _- --------- 14

Ammonite differentiation, Boreal,

Pacific, Tethyan realms .. 20 

Ammonites, Alaskan Jurassic, compared with those of other 

parts of world -_. _-_ SO 

Amoeboceras ....-_------_---___-.---_ 19,21

Arctic Ocean -_-__ .__ 20 

Arcticoceras .. -_- .. 20,21 

Arkelloceras ...___.-_-__..--___-__-__ 16,17 

Artocephalites ..... - 20,21

Bajocian fossil occurrences _ 23 

Bajocian seas, extent in Alaska -------- 17

Bathonian fossil occurrences _-- 24 

Bathonian seas, extent in Alaska 18 

Boreal realm ________________ 20,21 

Bowser Formation ______ --__--_ 14

British Columbia _________ 17,18,20,21 

Brooks Range ------ -_-.. 16

Buchia concentrica ................_ 19

fischeri ......... --------- 20

fischeriana ....................... IB

mosquensia ...................... 16,21

piochii ......._ __ ___ _ 15,21

rugosa ......._----------__-_.__ 15,21

Early Cretaceous species --_---___. 16

Cadoceras ..........------______ 16,21

(Paracadoceras) .................. 21

(Stenocadoceras) ..............._ 21

California _-------____-___-_ 20,21

Callovian ammonites, late, absence

in Alaska and Canada;

presence in California and

southern Mexico ___ ._. 16 

Callovian fossil occurrences ------_--_ 24

Callovian seas, extent in Alaska - _. 18 

Callovian to Oxfordian transition,

Southern Alaska _------ 8

Canning River ---_---_----._ _._ 16

Cape Lisburne ______________________ 14

Cardioceras .................... 15,16,19,21

Chinitna Bay __-______-_.__---_..___ 14

Chinitna Formation __________________ 15

Christian __--_______________ 14 

Coleen River __._____________ 14 

Concretions, limestone ______________ 9

orange-weathering clay ironstone. - 9 

Cook Inlet ...___...______ 8,15,17,18 

Cranocephalites -----------___..-- 16,20,21

Cretaceous rocks, marine ___..____.____ 2

Crucilobiceras ........................ 16

Depositiona] environment, Early to

Middle Jurassic time _____ 8

Dichotomosphinctes ..........__.__-__ 21

Disconformity, pre-late Oxfordian,

Root Glacier Formation. ._ 19 

Emergence, Callovian, early Oxfordian,

late Tithonian -..-_----- 14

Epieugeosynclinal trough 

Etivluk River __________

Page

8

16

Foraminifera, north-central Alaska, Late

Jurassic age Questioned _ 16 

Fossil occurrences by stages ________ Zl

Bajocian - _ _ _ 23 

Bathonian __--________-._ 24

Callovian ________________ 24 

early Oxfordian ----------_____ 25

Hettangian -----____________ 21

late Kimmeridgian to early

middle Tithonian -----_ 26

late middle to late Tithonian ___ 27 

late Oxfordian to early

Kimmeridgian -_______ 2B 

Pliensbachian _-.._.______ 22

Sinemurian _ _-_.________ 22

Toarcian --__..___________ 23

Greenland __.________________ 20,21

Guerrero, Mexico ._____.__________ 16

Gulf of Mexico, Jurassic salt

and red beds _______ 21

Hettangian fauna, Porcupine River ___ 14 

Hettangian fossil occurrences __-.._ 21

Iniskin Peninsula __-____..._ 2,14,17 

Inoceramus ambiguus __-_._.-_ 14,17,18 

Introduction ____________________-___ 1

Itkillik River ________________ 16

Juneau _______________------

Jurassic rocks, marine, absence in 

central Alaska _-

Kandik River ----_--_---.-_---.-_.._. 

Katmai .---------.--_._..-._.-_....

Kcpplerites .... ______________________

Ketchikan ...-.---- ..- -_.-

Killik River _______.. - -

Kimmeridgian, late to early middle

Tithonian fossil occurrences 

Kimmeridgian seas, extent in Alaska..

14

8

21

8

16

26

19

Kuskokwim ___________ 8,17,18,20

Late Kimmeridgian to middle Tithonian

seas, extent in Alaska ... 

Laumontite _____---__-____-_-_______.

Leioceras opalinum zone . .-_-___.__. 

Lilloettia ________________ ___________

Lithologic, stratigraphic features

compared ____ _--------

Lubbe Creek Formation ---------------

Lupine River _______________________

Lytoceras ...--------------------------

Marine connections between north and 

south Alaska in Jurassic 

time ----------- -------

Marine Cretaceous rocks _ ---------

Marine Jurassic rocks, absence in

central Alaska -----------

Marine Triassic rocks __.__._.___--_.. 

Megasphaeroccras rotundunt ...........

20

14

21

14

16

21

9

2

2

2

17

Mount Peulik

Naknek Formation _-_-.-_. 

Nation River ____ __._ __. 

Nizina Mountain Formation

Page 

15

15

14

14

Oaxaca, Mexico 16

Oil shale _______ 9

Okpikruak River _ 17

Otapiria taUleuri ....... - __ 16,17

Otoites sauzei zone . - - - - - - 14 

Oxfordian, early, fossil occurrences ._ 25 

late, to early Kimmeridgian

fossil occurrences .. 25 

Oxfordian seas, extent in Alaska 19

Pacific realm ____________ _ 20 

Paleobiogeographic resemblances,

differences during Jurassic,

northern and southern

Alaska -- __ 16 

Paleogeographic inferences, Alaska

Jurassic seas - 16 

Parabigotites crassicostatus .... _____ 17

Parareineckeia ....................... 20

Phylloceras ------- .-_ 21

Pliensbachian fossil occurrences 22 

Pliensbachian seas, extent in Alaska 16 

Plutonism __________________ 8 

Porcupine River ._.- __.-_-____---___ 14

Hettangian fauna -_. 14 

Pseudocadoceras ...................... 16,21

Puale Bay _____________-___ 15,18

Radiometric dating of igneous rocks.. 8 

Red beds, Jurassic, deposition in Gulf

of Mexico ___________ 21 

Root Glacier Formation, pre-late

Oxfordian disconformity... 19

Sagavanirktok River _-- .. ... 16, 17 

Salt, Jurassic, deposition in Gulf of

Mexico __-------- 21

Seas, Jurassic, extent in Alaska ______ 16

Sheenjek River ___. . _______-._-_- 14

Sinemurian fossil occurrences ._ 22 

Sinemurian seas, extent in Alaska ._. 16 

Stephanoceras humphriesianum zone... 14, 16 

Stratigraphic, lithologic features

compared _________ _____ 8

Stratigraphy, Jurassic rocks, eastcentral Alaska ... ----- U

northern Alaska --------- . .. 9

southern Alaska 8

Talkeetna Mountains 2,8,14,15,20 

Teloceras itinsae _____________________ 17

Tethyan realm ____.._ ... .. 20,21 

Tiglukpuk Creek __-..--. .. 14 

Tiglukpuk Formation, name abandoned 14 

Tithonian, late middle to late, fossil

occurrences . 27

33
34 INDEX

Page

Tithonian seas, extent in Alaska 20

Tmetoceras ...__________... ___. 1)6

Toarcian fossil occurrences - 23

Toarcian seas, extent in Alaska 16

Toarcian to early Bajocian unconformity 8

Triassic rocks, marine 2

Tuxedni Bay ....._______ 14

Twist Creek Siltstone ... 14

Unconformities, Jurassic, occurrences 14

Page

Unconformity, Bathonian-Callovian

boundary, northern Alaska 16 

late Bathonian, southern Alaska 14 

late Callovian, northern Alaska -_ 16 

late Callovian, southern Alaska __ 15 

late late Bajocian, southern Alaska 14 

late middle Bajocian to early

Bathonian, northern Alaska 16 

late Tithonian, Berriasian,

southern Alaska ____-___ 16 

middle Bajocian to early Bathonian 9

Page

Unconformity, Toarcian to early

Bajocian _________________ 8

top Lower Jurassic, southern Alaska 14

Volcanic island-arc system 8

Wide Bay ____________ 8,14,15,17,18,20

Wrangell Mountains __ 8,9,14,15,17,18,19

Xenocephalites ------ .-- ___ 20,21

Yukon Territory . 18,20

U.S. GOVERNMENT PRINTING OFFICE: 1973 SIS 659/63
Floods of June and July 1990 in and 

near Las Vegas, Nevada

By Otto Moosburner

The most significant and intense storms of a rather "wet" summer in the Las 

Vegas metropolitan area occurred on June 10 and July 15-16,1990. Although the 

mean annual precipitation in the area is about 4 inches, occasional floods, caused 

by intense rains in a rapidly urbanizing area, do occur.

Precipitation on June 10, from a moist unstable air mass associated with Tropical Depression Boris, totalled more than 1.5 inches in parts of Las Vegas immediately east and southeast of the downtown area. Most of the precipitation occurred 

within 1 hour. Maximum 15-minute intensities exceeded 3 inches per hour at several locations. Flooding was generated almost totally in and confined to the urbanized area as shown by the precipitation distribution (fig. 31).

The July 15-16 storm occurred west of the urbanized area in the headwaters 

and alluvial-fan areas of the Flamingo Wash drainage (fig. 32). Total rainfall in 

excess of 1.5 inches was recorded at a number of locations (an unofficial storm 

total of 2.5 inches was reported at one location). The storm generally lasted less 

than 2 hours.

Flamingo Wash is ephemeral, originates in the Spring Mountains west of Las 

Vegas, and drains generally eastward through central Las Vegas to join Las Vegas 

Wash in east Las Vegas. Las Vegas Wash flows to Lake Mead, an impoundment 

on the Colorado River. Since 1966, when flow records along Flamingo Wash 

began, five major floods have occurred in 1975, 1983, 1984, and two in 1990. 

The magnitudes of major Flamingo Wash floods are listed in table 27. Because of 

changes in channel-measuring conditions, flood discharges have not been determined at consistent locations.

The maximum discharge in Flamingo Wash on June 10 was small west of the 

urbanized area (site 1, table 27), but it increased substantially through town 

(site 5, table 27). Discharge remained high in Las Vegas Wash at the outlet of Las 

Vegas Valley (4,050 cubic feet per second at site 6). On July 16, the maximum 

discharge west of Las Vegas was extremely high (site 1, table 27) but attenuated 

greatly to 512 cubic feet per second in Las Vegas Wash at the outlet of Las Vegas 

Valley.

Two deaths were attributed to the June 10 flooding a woman drowned in her 

vehicle as she attempted to drive across a flood channel, and a man was swept into 

a manhole from which the cover reportedly had been removed. A woman died in 

the early morning hours of July 16 in Flamingo Wash when she was swept downstream from her vehicle while attempting to ford the flow. The June 10 and 

July 16 floods caused $8.7 million in damage to public facilities (Las Vegas 

Re view-Journal, August 1990).

REFERENCES

National Oceanic and Atmospheric Administration, 1990a, Climatological data, Nevada, 

June 1990: Asheville, N.C., National Climatic Data Center, v. 105, no. 6, 18 p.

___1990b, Climatological data, Nevada, July 1990: Asheville, N.C., National Climatic 

Data Center, v. 105, no. 7, 22 p.

Floods of June and July 1990 in and near Las Vegas, Nevada 93
115Q 15'

36Q 15' 

asefrom U.S Geological Survey digital data, 1 100,000,1986

NEVADA

Lines of equal precipitation based on data 

from U.S. Geological Survey (unpublished) 

and National Oceanic and Atmospheric 

Administration (1990a)

EXPLANATION

Index map

Approximate extent of Las Vegas 

urban area in 1990

 o.s Line of equal precipitation Interval 

0.5 inch

2

^ Flood-determination site Number 

corresponds to that in table 27

Figure 31. Location of flood-determination sites on Flamingo Wash, 1975-90, and lines of 

equal precipitation for storm of June 10,1990, in and near Las Vegas, Nevada.

94 Summary of Floods in the United States During 1990 and 1991
115=15

36a 15' 

Base from U S Geological Survey digital data, 1 100,000,1986 

Universal Transverse Mercator projection 

Zone 11

Lines of equal precipitation based on data 

from U.S. Geological Survey (unpublished) 

and National Oceanic and Atmospheric 

Administration (1990b)

EXPLANATION

Approximate extent of Las Vegas 

urban area in 1990

 o.s Line of equal precipitation Interval 

0.5 inch

^ Flood-determination site Number 

corresponds to that in table 27

Figure 32. Location of flood-determination sites on Flamingo Wash, 1975-90, and lines of 

equal precipitation for storm of July 15-16,1990, in and near Las Vegas, Nevada.

Floods of June and July 1990 in and near Las Vegas, Nevada 95
to

O)

0>

i

Q>

-3

Table 27. Maximum stages and discharges prior to and during floods of June and July 1990 in and near Las Vegas, 

[mi , square miles; ft, feet above an arbitrary datum; ft3/s, cubic feet per second; , not determined or not applicable. Source: Data from U.S. Geological Survey 

1$

O 

(O

to

0)

a

Site 

no. 

(figs. 

31

and

32)

1

2

3

4

5

6

Maximum prior to June 1990

Station no.

09419673

09419675

09419677

09419678

09419678.1

09419753

Drainage

Stream and place of area

determination (mi2)

Flamingo Wash near Torrey Pines Drive near 94

Las Vegas

Flamingo Wash at Las Vegas *98

Flamingo Wash at Maryland Parkway at 106

Las Vegas

Flamingo Wash near mouth at 117

Las Vegas

Flamingo Wash at Nellis Blvd. near 215

Las Vegas

Las Vegas Wash above Three Kids Wash I 2,l%0

below Henderson

Period

1988-90

1966-81,

1985-89

1969-87

1969-87

-

1988-90

Year

1989

1975

1983

1984

-

1989

DisStage charge

(ft) (ft3/s)

11.54 115

7.23 3,910

12.15 4,700

4,000

..

6.99 299

Maximum

Date

(month/

day)

6/10

7/16

-

-

-

6/10

7/16

6/10

7/16

'Approximately.