An Anvilian (early pleistocene) marine fauna from western Seward Peninsula, Alaska

QUATERNARY

RESEARCH

4,

441470

(1974)

An Anvilian (Early Pleistocene) Marine Fauna from Western Seward Peninsula, Alaska

D. M. HOPKINS,~ R. W. ROWLAND,~ R. E. ECHOLS,~ AND P.C. VALENTINE’ Received

September

16, 1974

Cover sediments of the York Terrace exposed near the California River, western Seward Peninsula, Alaska, yield mollusks, ostracodes, and foraminifera that lived during the Anvilian transgression of early Pleistocene age. The fossiliferous sediments lie at the inner edge of the York Terrace, a deformed wave-cut platform that extends eastward from Bering Strait along much of the southern coast of Seward Peninsula. The seaward margin is truncated by the little-deformed Lost River Terrace, carved during the Pelukian (Sangamonian) transgression. The early Pleistocene sediments seem to have been deposited between the first and second of four glaciations for which evidence can be found in thf, California River area. The California River fauna includes several extinct species and several species now confined to areas as remote as the northwestern Pacific and north Atlantic. The fauna probably lived in water temperatures much like those of the present time but deeper water on the Bering Shelf is suggested. The presence of an early Pleistocene fauna at the inner edge of the York Terrace at California River shows that the terrace was la.rgely rarved before and during early Pleistocene time. However, a marine fauna apparently of middle Pleistocene age is found on the York Terrace near Cassiterite Peak, and this seems to indicate that the terrace remained low until middle Pleistocene time. Uplift of the York Terrace probably was accompanied by uplift of Bering Strait. The strait may have been deeper, and there may have been no land bridge between the Seward Peninsula of Alaksa and the Chukotka Peninsula of Siberia during most of early and middle Pleistocene time.

INTRODUCTION The shores of western Alaska are fringed by marine terraces and coastal plains that preserve a rich record of changing sea level, local crustal deformation, and evolving moluscan faunas during late Tertiary and Quaternary time. Hopkins (1967) distinguished and named seven episodes of high sea level recorded on the Alaskan shores of the Bering and Chukchi Seas, beginning with the Beringian transgression of Plio‘U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025. ’ Oceanography Department, University of Washington, Seattle, WA 98105. s U.S. Geological Survey, Woods Hole Oceanographic Institution, Woods Hole, MA 02543.

cene age and ending with the Holocene rise in sea level (Table 1). Later studies have strengthened or clarified concepts of most of these high sea level events through discovery of new localities, enlarged faunas, and refinements in radiometric dating (Hopkins, 1972, 1973; Hopkins et al., 1972). Continuing field work, however, has weakened the concept of the Anvilian transgression, assumed to have taken place during early Pleistocene time. The stratotype for the Anvilian transgression is (‘Intermediate Beach,” a linear body of gold-bearing beach sand and gravel buried beneath glacial drift about 2.7 km inland on the coastal plain at Nome (Fig. 1). Int,ermediate Beach has yielded a dis441

Copyright AU rights

@ 1974 by University of Washington. of reproduction in any form reserved.

442

HOPKINS

ET

AL.

since collapsed. The few that did not collapse are clogged with ice. Thus, our underLATE CENOZOIC MARINE TRANSGRK3SIONS standing of the stratigraphy of the stratoIN WESTERN ALASKA type of the Anvilian transgression must be Krusensternian Holocene based on the few available published and Late Pleistocene (middle WisUnnamed” unpublished logs of mine shafts and boreconsinan) Late Pleistocene (Sangamon) holes and on the fossils on the tailings piles. Pelukian Middle Pleistocene Kotzebuan Hopkins (1967) suggested that the AnMiddle Pleistocene Einahnuhtan vilian transgression might also be repreEarly Pleistocene Anvilian sented by the fossiliferous marine deposits Beringian Pliocene at South Bight on Amchitka Island, at a The Woroneofian transgression, originally Black Bluffs on St. Paul Island in the Prithought to be of middle Wisconsinan age, has bilofs, at Skull Cliff, 63 km southwest of been shown to consist merely of a local submerPoint Barrow on the coast of the Chukchi gence of Cook Inlet, southern Alaska, about 13,000 y.a. (Schmoll et al., 1972; Hopkins, 1973), Sea, and at Atkasuk, 105 km south-southand the name Woronzofian transgression is hereby west of Point Barrow on the Meade River. abandoned. Reexamination of the mollusk fauna indicates that the shelly gravel at South Bight, Amchitka, was deposited during either the tinctive assemblage of fossil mollusks first Kotaebuan or, less likely, the Einahnuhtan considered to be of Pliocene age (Dali, transgression (Table 1) (Allison, 1973). 1920 ; MacNeil, Mertie, and Pilsbry, Pollen and diatoms in the fossiliferous 1943) but now thought to be of early Pleis- boulders at Black Bluffs indicate that they tocene age (Hopkins et al., 1960; Hopkins, are derived from a late Tertiary rather 1967). Unfortunately, independent inforthan an early Quaternary marine deposit mation bearing on the age of this fauna is (Hanna, 1970; J. A. Wolfe, paleobotanist, unavailable at Nome and, worse yet, the U.S. Geological Survey, unpublished data). stratigraphy of the fossiliferous deposit can Reexamination of the stratigraphy and no longer be directly observed. Anvilian de- mollusk fauna at Skull Cliff indicates that posits are not naturally exposed anywhere the marine sand and gravel there is probon the Nome coastal plain. Gold dredges ably of Pelukian (Sangamon) age (Table crossed Intermediate Beach only once, and 1) and that it is certainly no older than no geologist happened to visit the dredge middle Pleistocene (D. M. Hopkins, U.S. during the crossing. The Anvilian deposits Geological Survey and 0. M. Petrov, Geowere mostly mined by means of shafts. A logical Institute, Academy of Science, new shaft was dug each autumn; during the USSR, unpublished data, 1971). The molwinter, gold-bearing gravel was excavated lusk fauna at Atkasuk is similar to that in drifts radiating from the base of the at Skull Cliff (MacNeil, 1957), and the shaft and hoisted to a dump at the surface; geomorphic appearance and position of the and the dump was then sluiced early in the Atkasuk locality suggests a late Pleistocene following summer. The landscape at Nome age (Sellman and Brown, 1973; T. D. is dotted with the low mounds of tailings Hamilton, written communication, 1974). that were washed from winter dumps along A corollary problem is the age of the Intermediate Beach and elsewhere during York Terrace, a spectacularly deformed the first four decades of the present cen- marine terrace that extends along the coast tury. Mollusk shells commonly survived ex- of western Seward Peninsula (Fig. 2). A. cavation and sluicing and are still abun- J. Collier (1902) called attention to the dant in tailings piles, but most of the shafts high terrace in his pioneering report on the and drifts from which they came have long geology of western Seward Peninsula. AlTABLE

1

ANVILIAN

MARINE

FAUNA

IK

ALASKA

BEAUFORT

&,&‘iJ(&

2

\ Seward

443 SEA

Peninsula

Anchorage

.

FIG. 1. Index map showing places referred to in the text.

fred Knopf (1910) noted that the deformation of the high terrace indicates relatively recent uplift of western Seward Peninsula and that uplift must be considered in dis-

cussions of the Bering land bridge. Steidtman and Cathcart (1922) presented the first adequate topographic map of the deformed high coastal terrace of western

HOPKINS

444

KANAUCUK

ET

AL.

RIVER

5’

FIG. 2. Geography of western Seward Peninsula, showing York Terrace and correlative early and middle Pleistocene terrace and coastal plain areas (shaded), and major faults (hachures on the downthrown side).

Seward Peninsula. But the age of the terrace remained unknown. C. L. Sainsbury proposed the name York Terrace for the high terrace4 and also named and described the Lost River Terrace, a narrower and less-deformed low ter-

race formed during the last interglaciation (Sainsbury, 1967a,b). He found several areas in which marine sediments are preserved on the York Terrace. A small assemblage of fossil moIIusk shells, apparently of middle Pleistocene age, was found

’ Sainsbury (1967b) proposed the name “Fish Creek Terrace” for the high marine terrace east of the California River, as he was not confident that it was carved synchronously with the York Terrace west of the Don River (Fig. 2). Although

we concede that the high terrace has evidently been carved at different times in different places, we prefer to use the name York Terrace for the morphologically similar terrace throughout western Seward Peninsula.

ANVILIAN

MARINE

on the terrace surface next to a low cliff eroded in cemented beach gravel at the base of Cassiterite Peak, about 9 km east of Lost River (lot. M1732, Fig. 3).

FAUNA

IN

ALASKA

445

In 1966, Sainsbury (196713) discovered another, much richer fossiliferous marine deposit in bluffs on the west side of the Calfornia River and in the banks and bet1 of

Modern beach deposits

_ Drift of York Glacmtion

I

of Killestok Creek

FIG. 3. Cenozoic geology of part of western Seward Peninsula based on Sainsbury (1967a, b) and field mapping and photointerpretation by D. M. Hopkins in 1973. Inset delineates are as shown in Fig. 4. Base from U. S. Geological Survey 1:250,000 (Teller, 1950).

446

HOPKINS

Killestok Creek,5 an ephemeral stream that enters California River from the west on the inner part of the York Terrace (10~s. M6365-M6368, Fig. 3). Subsequent study has shown that the California River and Killestok Creek localities contain a molluscan fauna of Anvilian age and that foraminifers and ostracodes are present as well. Exposures are good, and the stratigraphy can be studied in detail. The California River and Killestok Creek localities provide the desired new locality of fossiliferous marine deposits of Anvilian age in a clear and readily observable stratigraphic setting, and they cast new light on the age of the York Terrace. Field work for the present report commenced in June 1966, when Hopkins briefly visited the California River locality with C. L. Sainsbury. In July 1968, Hopkins and Rowland spent half a day at the California River and Killestok Creek localities and made larger fossil collections. In July 1973, Hopkins, assisted by R. E. Nelson, conducted a helicopter-supported survey of the Cenozoic geology of western Seward Peninsula. Hopkins and Nelson spent 3 days at California River, during which they excavated and measured many sections, screened large volumes of marine sand for mollusks, and collected samples for granulometric and microfaunal analysis. GEOLOGY Regional Setting

The York Terrace is an ancient shoreline feature of the northernmost part of the Bering Sea, lying near the connection through Bering Strait to the Chukchi Sea and the Arctic Ocean (Fig. 1). The terrace is carved into the seaward face of the York Mountains and into the rolling hills to the east (Fig. 2). Inland from the terrace, the hills of western Seward Peninsula

display

‘Killestok Creek, named here for the first time, is even the Inupik Eskimo name meaning “fossil shell,” as related to us by Mrs. Bessie Moses of Nome, Alaska.

ET

AL.

a well-defined summit surface which represents the remnant of a subaerial erosion surface of mid-Tertiary age---the Kugruk Plateau of Collier (1902). The York Mountains

occupy

an area where the Kugruk

Plateau has been uplifted, and the summit surface loses definition there owing to thorough dissection. The York Terrace extends as a continuous landform from Teller westward to the mouth of the Kanauguk River (Fig. 2). The terrace ranges in width from less than 1 to more than 8 km. The inner margin stands at an altitude of about 50 m in the area north of Teller, at about 225 m west of Lost River, and at about 180 m 011 the east side of the Kanauguk River. The original shoreline is buried in some places by moraines, alluvial fans, and colluvial aprons up to 20 m thick; in other places, the terrace has been lowered below its original level by glacial scouring. The altitudes of the inner margin cited above represent the surfaces of nonmarine sediments covering the shoreline angle. The actual height of the innermost shoreline may be as much as 20 m lower at any given point. Even so, it is clear that, the terrace has undergone at least 150 m of differential warping. The highest part of the terrace lies in front of the highest, and most rugged part of the York Mountains, suggesting that the deformation of the terrace was accomplished by the tectonic processes that caused the uplift of the mid-Tertiary erosion surface, Collier’s (1902) Kugruk Plateau, to form the York Mountains. Marine geologic studies show that northern Bering Sea and Bering Strait are tectonically active areas. A west-trending normal fault forms a south-facing scarp at the entrance to Bering Strait, and a west-trending rift, 4-8 km wide and filled with layered rock probably of Tertiary age, extends parallel to and near the south coast of western Seward Peninsula in the area of the York Terrace (Grim and McManus, 1970, Hopkins, Nelson, and Perry, unpublished data) (Fig. 2). The deformation of the

ANVILIAN

MARINE

York Terrace and the uplift of the York Mountains probably took place during movement along these faults. The Lost River Terrace, a younger, narrower, and lower marine terrace, separates the York Terrace from the present shoreline. The Lost River Terrace was carved during the Pelukian transgression of Sangamon age (Table 1) (Sainsbury, 1967a,b; Hopkins, 1973). It ranges from a narrow 100 m to more than 3 km in width. It is much less deformed than the York Terrace! and the shoreline angle lies at present altitudes of 5-10 m. The boundary between the Lost River and the York Terrace is an abandoned sea cliff, spectacular in the places where the York Terrace stands 100 m or more above the Lost River Terrace. The York and Lost River marine terraces and the hills farther inland are underlain by complexly deformed limestone of early Paleozoic and possible Precambrian age (Sainsbury, 1972). The rigorous climate and the limestone substrate are unfavorable for plant growth, and much of the region is an arctic desert. Consequently, geologic exposures are excellent. Much of the surface of the York Terrace consists of barren limestone rubble broken from bedrock by frost action; other areas are mantled by Quaternary sediments bearing only a sparse plant cover. The limestone is cavernous; sink holes are common on the York Terrace but not on the lost River Terrace. The California

River Basin

The California River is the remnant of a river system that was once much larger, having received the drainage of Arctic Creek and the upper course of the Agiapuk River (Fig. 2). These former tributaries were diverted into the main stem of the Agiapuk River upon the eruption of basaltic lava flows that now form the eastern divide of the California River between 6 and 14 km upstream from the mouth. The southernmost lava flow terminates southward in a straight scarp, 5 m high, extending parallel to the inner edge of the York

FAUNA

IN

ALASKA

447

Terrace (Figs. 3 and 4). We interpret the scarp as an erosional cliff that has retreated from an original position somewhat to the south, where it had been formed by wave attack at the inner edge of the York Terrace (Fig. 5). The lava flow is paleomagnetically normal (field determinations of three specimens by flux-gate magnetometer) and has a potassium-argon age of 2.84 & 0.14 m.y. (Table 2). The flow was emplaced during late Pliocene time, within the Gauss normal paleomagnetic epoch. The 2.8 m.y. age of this flow places a maximum limit on the possible age of the York Terrace, and it provides an approximation of the time when the eastern tributaries of the California River were diverted into the Agiapuk. The York Terrace extends about 6 km inland in the California River area. The seaward boundary is formed by the wavecut scarp of the Lost River Terrace, about 3 km from the present shore. The California River flows near the eastern limit of an area that has been repeatedly overridden by glaciers nourished by snowfields in t,he York Mountains. Sainsbury recognized evidence for two glacial episodes in the California River area; our deta;led studies provide evidence for three, and perhaps four glaciations. The most recent glaciation is recorded by a well-defined moraine marking the eastern margin of a glacier that came down the Don River Valley, then expanded as a piedmont bulb on the surface of the York and Lost River Terraces (Fig. 3). This moraine is shown as defining the eastern limit of the York Glaciation in the earlier of Sainsbury’s two 1967 papers; in the later paper, he reports radiocarbon-dated samples that show that the York Glaciation took place prior to 11,009 y.a. The radiocarbon dating and the relation to the Lost River Terrace indicate that the York Glaciation is of Wisconsin age. After completing the manuscript for his earlier 1967 paper, Sainsbury discovered subdued moraines farther northeast on the

448

HOPKINS

ET

AL.

65’25 EXPLANATION

Flood-plain alluvium of California River

Ancienl and modern alluvial fans

Drift of York GliciatianGym, moraine; Qvo. outwas

Marine sand and graV@l of the Pslukiin IrWWgreWiOI on the York Terrace

Drift of Nome River Grclatic

Glacial drift, probably older than Nome River Glaciation

Basaltic lava flow

65”20I 166-w Bare from U 5. Geological Survey 1.63 360 Teller B-4,1950 * i 2

16625

Geology by DM Hopkins, 1973

7

4

5 hlL
CONTOUR INTERVAL 15 METRES(DASHED LINES REPRESENT 7.5 METRES)

Fault scarp . . . . . . . . ...**.. Buried shoreline at inner edge of York TerrB~

FIQ. 4. Geology of the California

River area. Geology by D. M. Hopkins

York Terrace, extending along Killestok Creek, and he found till in the east bank of the California River a short distance downstream from Killestok Creek. Sainsbury (1967b) then took this moraine and the new till exposure to define the eastern limit of the York Glaciation. Our more detailed study shows that the moraine along Killestok Creek and similar moraines east of the California River are truncated by the inner edge of the Lost River Terrace (Fig. 3). These moraines are similar in morphology and stratigraphic position to the moraines of the Nome River Glaciation of central Seward Peninsula. They were

(1973).

probably formed during the penultimate (latest pre-Sangamon) glaciation (Hopkins, 1973). Glacial drift that may be considerably older occupies an area at least a kilometer wide northeast of Killestok Creek. Airphoto patterns suggest that this presumed older drift is also present on the east side of the California River. The drift north of Killestok Creek is poorly exposed because it has been stripped away by solifluction in areas adjoining river bluffs and gully walls; the edge of the drift commonly forms low scarps 100 m or more back from the main bluffs (Fig. 5). Except for these scarps, the

ANVILIAN

MARINE

FAUNA

II-C

ALASKA

450

HOPKINS

TABLE

2

ARGON AND POTMZJUM ANALYTICAL DATA FOR POTMSIU.VE-ARGON AGE REPORT MP-101 (S.L.IPLK 73Ahp 7, B \S.ILT,~ COLLECTED 1N

THE

UiVlDE

RIVEE

BP:‘TWEI’>N

AND

CALIFORNI.4

ARCTIC CREEK)

Argon analys& Potassium analysid (percent KzO)

Ar 401 (moles/g)

A+& Ar%ts~

0.875 0.865 0.867 0.859 Average 0.866

3.633 X lo-r0

0.40

Apparent age

2.84 +_ 0.14

0 Whole rock analysis. b Potassium measurements were done on I. L. flame photometer using lithium internal standard. Analyst: Lois S&locker. c Argon measurements were made using standard techniques of isotope dilution. Analysis and age computations by J. C. von Essen. H40 decay constants: X, = 0.585 X lo-r0 yr-1; An + 4.72 X 10-r” yr-1. Abundance ratio: K40/K = 1.19 X lo-r0 atom percent.

older drift lacks distinctive topography. Although we lack stratigraphic evidence, we think that the drift north of Killestok Creek was probably deposited during a middle Pleistocene glaciation older than the Nome River Glaciation. The earliest glacial episode is recorded by the Skull Creek erratics, large angular boulders of biotite-andalusite hornfels apparently derived from Black Mountain that are scattered on limestone ridges in the California River valley (Sainsbury, 196713) (Fig. 3). There are no coherent bodies of drift associated with the Skull Creek erratits, and the boulders lie far outside the outer moraines of the York and Nome River Glaciations. The Skull Creek erratics are clearly very old. They may be correlative with the formless drift north of Killestok Creek, but we shall present evidence suggesting that they are much older. Northwest-trending faults have affected the topography of the California River area. A swarm of faults near the inner edge

ET

AL.

of the York Terrace is marked by short, straight gullies and by linear stripes of dark vegetation recognized on air photos. A zone of recemented limestone breccia is exposed in the west bank of the California River at the point where the river crosses the northernmost of these faults. We did not look for and did not recognize surface scarps along the traces of the faults near California River, but a northwest-trending fault makes a scarp about 10 m high across one of the lava flows in the upper Agiapuk River basin (Fig. 3). The California River Fossil Localities

and Killestok

Creek

The California River flows in a narrowly confined channel in its course through the bedrock hills north of the York Terrace; the flood plain widens abruptly at the point where the river debouches onto the terrace. Below that point, the river has a braided floodplain several hundred meters wide, confined laterally by bluffs lo-30 m high. Fossiliferous marine deposits, 5-15 m thick, associated with the York Terrace and overlain by the ancient formless drift, are exposed in these bluffs for about a kilometer upstream from Killestok Creek (Figs. 5 and 6) and in the walls of Killestok Creek itself. South of Killestok Creek, drift of the Nome River Glaciation rests directly on the limestone bedrock, and the marine deposits evidently have been eroded away. The abrasion platform of the York Terrace is well exposed beneath the marine sand and gravel in the bluffs along the west side of the California River from the mouth of Killestok Creek to a point about 0.5 km upstream. Farther upstream, the abrasion platform apparently lies below river level. The shoreline notch evidently lies about 1 km upstream from Killestok Creek, for beginning at that point, the bluffs are mantled with angular limestone rubble devoid of rounded boulders and exotic rock types. The surface of the wavecut platform is also exposed in many places in the banks of Killestok Creek from the confluence with the

FIG. 6. Panorama of Anvillian deposits exposed in west bank of the California River betFeen first and second gullies upstream from Xillestok Creek (Fig. 3). Scale given by figurr at left center. Cliff-forming hed just upslope from figure is cemented breccia of the elastic wedge,

California River to a point 1.7 km upstream. Above that point, the wave-cut platform lies below creek level. Based on our hand-leveling for Fig. 5 and upon the reconnaissance contours given on the Teller B-4 quadrangle (1: 63,360, U.S. Geological Survey, 1950), we estimate that the shoreline angle of the York Terrace lies at an altitude of about 35 m in the California River area. Limestone exposures on the seaward part of the York Terrace are noticeably higher than exposures of the abrasion platform farther inland near Killestok Creek, and this led Sainsbury (1967b) to believe that the shelly marine sand and gravel had been deposited in a stream valley carved into the terrace. Detailed study shows, however, that the anomalies in the altitude of the terrace surface result from tectonic deformation. Killestok Creek flows down the axis of a synclinal flexure, and the abrasion platform is at a low point at the m%uth of the creek (Fig. 5). Correlation of key beds indicates that the abrasion platform and the overlying marine beds have also been displaced across each of several small southeast-trending faults that cross California River upstream from Killestok Creek (Fig. 5). In most places; the abrasion platform is covered by about a meter of clean, open-

work pebble gravel containing a few lirncstone boulders to 0.5 m across. The gravel grades upward into well-sorted fine sand containing an admixture of well-rounded granules and pebbles mostly less than 1 cm in diameter. The sediment coarsens northward, and beds of gTave1 appear throughout the section near the shoreline notch. Weakly cemented zones are encountered in the lower and middle part of the section, and cementation increases as the shoreline notch is approached. About 90% of the pebbles in the gravcsl and pebbly sand are of limestone. The rest are vein quartz, granite, talc-silicat,c tilCtite, lamprophyre, vesicular basalt, ailtstone, phyllite, and schist. Some of tht:se rock types crop out within the upper California River basin, but the granit’c and tuctite must be derived from valleys farther west in the York Mountains. A wedge of coarse, poorly sorted, and firmly cemented elastic material (the ‘Leonglomerate of continental origin” of Sainsbury, 196713) extends seaward from the shoreline notch in exposures on the w& bank of the California river (Figs. 5 and 6). The elastic wedge appears near the middle of the marine section and is at least 4.5 m thick near the shoreline notch. It thins seaward and interfingers with the pebbly sand. At a point 500 m seaward from the

452

HOPKINS

FIG. 7. Coarse breccia making up the elastic wedge in the Anvillian deposits exposed on the west side of the California River about 200 m seaward from the former shoreline. Note lack of fabric due to diverse orientation of the large clasts. Location shown in Fig. 5.

shoreline notch, it consists merely of three 20-cm beds of silty or sandy gravel, each separated by about 1.5 m of pebbly sand. In the upstream exposures, the elastic wedge is a thick-bedded breccia of angular, diversely oriented limestone clasts supported in a firmly cemented sandy matrix (Fig. 7). Although poorly sorted, the breccia seems to lack components finer than fine sand, and it contains pockets of open-work gravel. Most of the limestone clasts are 1 or 2 cm across, but blocks as large as 20 cm across are included. A few well-rounded pebbles suggestive of beach pebbles are scattered through the deposit, and the breccia contains a few irregular, subrounded boulders of lamprophyre and basalt as much as 1.5 m across. Granite cobbles up to 12 cm across are present, though rare; some of the granite cobbles are fresh and firm, but others are friable and rotten and seem to have been deeply weathered prior to incorporation into the breccia. Seaward, the elastic wedge grows less coarse, the clasts become more rounded, the matrix better sorted. At a point 400 m sea-

ET

AL.

ward from the shoreline notch, the deposit consists of a gravel of rounded and subrounded pebbles (the largest 7 cm across), still randomly oriented, and with interstices filled with micaceous sand. Several thick, stubby sand lenses are composed of angular medium sand quite different in texture from the fine to very fme pebbly sand that lies above and below the elastic wedge. A sample from one of the sand lenses contained abundant foraminifera (&a. 22, Fig. 5). The elastic wedge probably represents a flood deposit, possibly a mudflow, brought down the California River when the shoreline stood at the inner edge of the York Terrace. The exotic boulders are too large to have been brought along the coast from remote sources by longshore drift. The basalt boulders may well have been derived by erosion of the basaltic lava flow that still overlooks the inner margin of the York Terrace, and the lamprophyre may have been introduced from farther up the California River. There are no granite outcrops in the California River basin; granite is represented there only by the Skull Creek erratics. We suggest that the elastic wedge consists of material flushed from the vaIIey of the California River during a violent flood that incorporated glacial till once associated with the Skull Creek erratics, as well as materials derived from local bedrock. If this interpretation is correct, then the Skull Creek erratics were deposited during a glacial episode older than the cutting of the York Terrace. FAUNA The marine beds in the California River area contain fossil mollusks, ostracodes, and foraminifera (Table 3).6 Although individual fossils are abundant, diversity is low. Among the mollusks, 31 taxa are recognized, of which 24 can be determined ‘The mollusks and microfossils discussed in the report are deposited in the paleontological colbction of the United States Geological Survey in Menlo Park, California.

ANVILIAN

MARINE

FAUNA

TABLE FAUNA

OF ANVILIAN

DEPOSITS

IN

3

AT CALIFORNIA

RIVER

Stratigraphic OP

biogeographic significance”

Taxon

453

ALASKA

AND

KILLESTOK

CRIWK

Occurrenceh and :tbtmdancaec -__-. -.__ California River BInffs KilIestok Lowe+ &liddlee Tlpperl Creeko

Mollusca Bivalvia Mytilus edulis Lin& Swiftopecten swiftii

a

(Bernardi,

1858)

Chlamys sp. Pododesmus macroschisma (Deshayes, 1839) Astarte diversa Da& 1920 Astarte lefingwelli Dal], 1920 Astarte borealis arctica ray, 1824 Astarte sp. Cyclocardia crebricostata nomensis (MaeNeil,

1943) C&ocardia

c r

Pat E? Ber E E E?

0

(VT) r

r vr f r

I3

(Krause, 1885) Serripes gronlandicus (Brugui&e, 1789) Gomphina JEuctuosa (Gould, 1841) Spisula polynyma (Stimpson, 1860) Siliqua alta (Broderip and Sowerby, 1829) Tellina lutea alternidentata Broderip and Sowerby, 1829 Macoma sp. Mya truncata LinnB, 1758 Mya arenaria LinnB, 1758 crebricostata

At1

Gastropoda

L&or&a

squalida Broderip and Sowerby, 1829 Littorina sitkana (Philippi, 1845) Littorina cf. L. obtusata (LinnB, 1758) Tachyrhyncus erosus (Couthouy, 1838) Trichotropis cf. T. insignis Middendorf, 1849 Polinices pallidus Broderip and Sowerby, 1829 Natica clausa Broderip and Sowerby, 1829 Natica cf. N. janthostoma Deshayes, 1839 Boreotrophon beringii (Da& 1902)

(0

Ber At1

(’

Pat

VI

r

Colid, sp. 1 Colid, sp. 2 Neptunea, sp. 1 Neptunea, sp. 2 Ostracoda Cythere sp. (juv.) “Cytheretta” teshepukensis Swain, 1963 Cythcromorpha? sp. Hernicythere borealis (Brady, 1868) Lozoconcha venepidermoidea Swain, 1963 _Vormanicythere leioderma (Norman, 1869) Rabilimis septentrionalis (Brady, 1866) (juv.) Robertsonites tuberculata (Sars, 1865) Foraminifera Oolina borealis Loeblich and Tappan, 1954 Dentalina ittai Loeblich and Tappan, 1953

Dentalina

sp.

r I: T (cl

Arc E? At1 Arc Arc Arc-All

f (f) w CC) CT) f (r)

vr

f

vr

r

c

r I

r c vr

454

HOPKINS

TABLE

ET

AL.

3 (Continued)

Taxon

Stratigraphic or biogeographic significancea

Occurrence* and abundanceC California Lowerd

River Bluffs

Middle0

Upperf

Killestok Creek0

Poraminifera Globulina glacialis Cushman and Ozawa, 1930 Pseudopolymorphina ishikawaensis Cushman and Osawa, 1929 Pseudopolymorphina ligua (Roemer, 1838) Sigmomorphina undulosa (Terquem, 1878) Sigmomorphina sawanesis Cushman and Ozawa, 1929 Glundulina laevigata d’orbigny, 1826 Fissurina sp. Bolivina sp. Bucella frigida (Cushman, 1922) Bucella inusitata Andersen, 1952 Elphidium bartletti Cushman, 1933 Elphidium clavatum Cushman, 1930 Elphidium oregonense Cushman and Grant, 1927 Elphidium subarcticum Cushman, 1944 Eliphidiella hannai (Cushman and Grant, 1927) Elphidiella nitida Cushman, 1941 Elphidiella aff. E. sibirica (Goes, 1894) Protelphidium orbiculare (Brady, 1881) Cribrononion incertum (Williamson, 1858) Cribrononion obscurus Gudina, 1969 Nonionella miocenica Cushman, 1926 Globorotalia pachyderma (Ehrenberg, 1861dextral)

E E? At1

r

f

r

C

a

a

r

r 6) r

r

f vr

vr

(r) vr c

C

C

vr (r) C

Ber

C

a Pat Ber E?

(4

Pat

F a a (vr)

Ber

r

C

r f r

C

C

C

vr r a C

a r

C

a

c

a Arc = Arctic species not presently living south of Bering Strait; At1 = species presently restricted to Atlantic and eastern Arctic; Ber = species reaches northern limit in Bering sea; E = extinct; Pat = species presently restricted to Pacific Ocean. r, Occurrences listed in parentheses are from uncertain stratigraphic position. c Abundances indicated as Very Rare (vr) = 1; Rare (r) = 2-5; Few (f) = 6-15; Common (c) = 16-100; and Abundant (a) = more than 100. d USGS mollusk locality M-6365 and microfossil locality Mf-1445, which lie below the elastic wedge in the California River bluffs (Fig. 5). #Localities M-6366 and Mf-1446, which lie within the elastic wedge or at equivalent level further seaward in the California River bluffs (Fig. 5). /Localities M-6367 and Mf-1447, which lie above the elastic wedge in the California River bluffs (Fig. 5). g Localities M-6368 and Mf-1448, which lie in the banks and bed of Killestok Creek.

to species. The foraminiferal fauna comprises 25 taxa of which 22 can be identified at the specific level. The ostracode fauna consists of eight taxa of which six can be determined to species. The molluscan material is rather poorly preserved. Complete shells of the smaller species are fairly common, but the larger

species are represented mostly by fragments. Surface frosting, a result of secondary calcite overgrowths or incipient solution, make it difficult to see details on foraminiferal tests, but this di5culty was overcome by staining specimens with food dye. Ostracodes are severely abraded, and only the most robust forms are preserved.

ANVILIAN

MARINE

The molluscan fauna from Killestok Creek is considerably richer and more diverse than the fauna obtained from exposures along the California River, but the California River bluffs yielded a much more diverse microfauna (Table 3). Nevertheless, faunas from both localities seem to be of essentially the same age. Mollusks indicative of an early Pleistocene age were collected in the Killestok Creek exposures and from the upper part of the California River section and microfossils indicative of an early Pleistocene age were collected below, within, and above the breccia wedge in the exposures along the California River.

FAUNA

IN

ALASKA

455

several examples of both valves can be found. Pododesmus snacroschisma reaches its present northern limit in northern Bering Sea (Rowland, 1973). Pododesmus macroschisma is a common fossil in Anvilian and Pelukian (Sangamon) deposits at Nome but has never been found as a fossil north of Bering Strait. The genus Astarte is represented by scvera1 species. Astarte diversa is characterized by its distinctive shell sculpture (Plate I, Figs. 4 and 5). Astarte lefingwelli is represented by a single hinge fragment (Plate I, Fig. 6). Both of these extinct species occur in Beringian and Anvilian deposits S ys tenaa tic, Biogeographic, and at Nome, and A. lefingwelli is found in Biostratigmphic Notes Beringian beds on the Colville River and Mollusks. Two small fragments of in late Pleistocene deposits near Point BarChlnm ys (Swiftopecten) swift2 (Plate 1, row (MacNeil, Mertie, and Pilsbry, 1943; Figs. 1 and 2) were obtained (Fig. 5). Dal1 MacNeil, 1957; Petrov and Hopkins, un(1920) described this taxon as Pecten published data, 1971). Complete juvenile specimens and frag(Chlamys) kindlei, based on specimens from Intermediate Beach (Anvilian) at ments of larger valves of Astarte borealis Nome. MacNeil (1967) discussed the simi(sensu Zatu) were collected. Following Pclarity between Dali’s taxon and the living trov’s (1966) terminology, the large fragnorthwestern Pacific C. (8.) swift% The ments (Plate I, Figs. 7 and 8) are classified as A. b. arctica Gray. The California River latest reviser, Masuda (1972), examined the type specimens of P. (C.) lcindlei and occurrence may represent the earliest appearance of A. borealis in Bering Sea. Anviconsidered them to be C. (8.) swiftii. lian beds at Nome contain only the closely ChZnm?ys (8.) swiftii is presently restricted to the coastal waters of the Japanese Is- relat’ed A. nortonensis MacNeil. Two other Astarte fragments (Plate I, lands, east Korea, Sakhalin IsIand, and Figs. 9 and 10) display an anterior umthe Kurile Islands, but during late Terbona1 ridge and consequently do not belong tiary and early Quaternary time, the to any of the species named above. species ranged around the north and east Cyclocardia crebricostata is very abunPacific to California (Masuda, 1972). dant,. The typical form and C. c. nomensti The large and well-preserved right valve of another Chlamys (Plate I, Fig. 3) col- MacNeil occur togeOher at California River and in Beringian and Anvilian deposits at! lected on the slope of a gully entering California River (Fig. 5) cannot be referred to Nome. C. c. nomensis (Plate I, Figs. 11 and any fossil or living species and appears to 12) is characterized by more rounded and be undescribed. In overall shape and rib more numerous radial ribs. In recent collections from the Bering Sea, no specimens of spacing, the specimen is similar to Chlamys C. c. nomensis were obtained iRowland, beringiana colvillensis MacNeil, 1967, but 1973). The disappearance of this form repthe right valves of this species have tripartite ribs, whereas the specimen at hand has resents a reduction in the intraspecific varibipartite ribs. To describe this specimen as ation of C. crebricostata, the cause of which is unknown. a new species would be premature, until

PLATE

I

38

6A

?A

PLATE I. Mollusks from the California River and Killestok Creek outcrops. Fig. 1. SW+ topecten swiftii (Barnardi) M-6367, X2. Fig. 2. ChZumys sp. M-6367, Xl. Fig. 3. Astarte diversa Dal1 M-6368, x2, 3a exterior, 3b interior. Fig. 4. Astarte Zefingwelli Dal1 M-6368, x2. Fig. 6. Astarte borealis arctica Gray M-6368, Xl, 5a exterior, 5b interior. Fig. 6. Astarte sp. M-6368, x2, 6a, exterior, 6b interior. Fig. ‘7. Cyclocardia crebricostata nomensis (MacNeil) M-6368, Xl, 7a exterior, 7b interior.

PLATE

If

6

9 8

PLATE II. Molluaka from the California River, Killestok Creek, and Cassiterite Peak outciops. Fig. 1. Macoma sp. M-6368, x2. Fig. 2. Mva truncata Linne M-6368, x2. Fig. 3. Mytr arenaria Linne M-6368, x 1.5. Fig. 4. Littorina squalida Broderip and Sowerby M-6367, xl. Fig. 5. Littorina sitkana (Phillippi) M6368, x3. Fig. 6. Littorina cf. L. obtumta (Linne) M-6368, x3. Fig. 7. Polinices pallidus Broderip and Sowerby M-6368, x2. Fig. 8. Natica clausa Broderip and Sowerby M-6368, x3. Fig. 9. Natica cf. N. janthostoma M-6368, x1.4. Fig. 10. Boreotorphon be&&i (Dali) M-6368, Xl. Fig. 11. Colid sp. 1 M-6368, Xl. Fig. 12. Colid sp. 2 M-6368, Xl. Fig. 13. Neptunea sp. 1, fragment M-6368, xl. Fig. 14. Liomesius ooides canaliculatus (Dali) M-1732, xl. Fig. 15. Neptuneu heros heros (Gray) M-1732, x1. 457

458

HOPKINS

A single valve of Maco?na similar in shape to Macoma balthica was collected. The pallial sinus (Plate II, fig. 1)) however, is much smaller than M. balthica (see Coan, 1971). Although no complete valves of Mya were found, spoons belonging to Mya truncata (Plate II, Fig. 2) and M. urenaria (Plate II, Fig. 3) could be identified. The presence of M. arenaria in the California River beds is interesting, because the species has not been recorded previously as a fossil in Alaska (MacNeil, 1967). The modern natural range of this species is the North Atlantic, although it has been reintroduced by man to the Pacific coast of the United States and Canada. MacNeil (1957: 14-17) shows that the species originated in the North Pacific during the late Miocene, dispersed into the North Atlantic soon after, and became extinct in the Pacific region during latest Tertiary or earliest Quaternary time. Specimens of Littorina are abundant, being the secondmost numerous taxon after Cyclocardia crebricostata. Dr. J. Rosewater (U.S. National Museum) examined specimens from our collection. All except three of the specimens are referable to L. squulida (Plate II, Fig. 4). One fragment is L. sitkana (Plate II, Fig. 5)) a species now living in the northeastern Pacific and the southern Bering Sea. Two other fragments are closest to L. obtusata (Plate II, Fig. 6)) an Atlantic-Arctic species not presently known west of Hudson Bay (MacPherson, 1971). Littorina obtusata is a senior synonym of L. palliata, the species name used by MacNeil, Mertie, and Pilsbry (1943) for specimens from Pelukian (Sangamon) deposits at Nome. The Naticidae were identified by L. Marincovich (U.S. Geological Survey). Polinices pallidus (Plate II, Fig. 7) and Natica clausa (Plate II, Fig. 3) are common. There is only one specimen, an incomplete one, that could possibly represent Natica janthostoma, (Plates II, Fig. 9), although N. janthostoma is the predomi-

El’

AL.

nant naticid in Anvilian deposits at Nome. The species is now restricted to the northwestern Pacific Ocean from Japan to Kamchatka but ranged eastward to Oregon and California during late Tertiary and early Pleistocene time (Marincovich, 1973). Ostracodes. The modern distribution of ostracodes is less well known off western Alaska than are distributions of mollusks and foraminifers. Nevertheless recent studies by Painter (1965) and Hazel (1967) and samples studied by Valentine from northern Bering Sea and the Beaufort Sea provide general information on the modern distribution of the fossil ostracode species in the California River fauna. Additional information is provided by unpublished studies by J. E. Hazel of fossil ostracodes collected by Hopkins around Kotzebue Sound, at Nome, and in boreholes drilled from the R/V VIRGINIA CITY in 1967 offshore at Nome (J. E. Hazel, written communications, 4/g/68,6/4/68). Tytheretta” teshepukensis occurs in the Gubik Formation and in middle and late Pleistocene deposits around Kotzebue Sound. It is found living today north of Point Barrow. Cytheromorpha? sp. is an unidentified form that apparently has not been found previously in fossil deposits nor in modern bottom samples in the Bering-ChukchiBeaufort Sea region. Normanicythere leioderma occurs in the Pleistocene deposits of northern Alaska and in the Bootlegger Cove Clay, a late Pleistocene glaciomarine deposit near Anchorage, Alaska. The modern distribution of N. leioderma includes the North Atlantic Ocean, the Beaufort Sea, the Chukchi Sea, and northern Bering Sea. Hemicythere borealis occurs today in the eastern and western North Atlantic and has never been reported living in the Beaufort, Chukchi, or Bering Seas. It is known as a fossil in the Gubik Formation of northern Alaska. Robertsonites tuberculata ranges through

ANVILIAN

MARINE

the Bering and Beaufort Seas and into the North Atlantic, and is found as a fossil in the Gubik Formation. Loxoconcha venepidermoidea is reported only from the Beaufort Sea, but fossil L. venepidermoidea has been found in Submarine Beach (Beringian) at Nome and in middle Pleistocene deposits around Kotzebue Sound as well as in the Gubik Formation. Rabilimi-s septentrionalis (= Pseudocythereis simpsonensis Swain, 1963, Plate 97,

Figs. 4, 12, 16, 20; Plate 98, Figs. 21a-d; Plate 99, Figs. lOa-c; text Fig. 12a) is a common ostracode at California River and is evidently an indicator of a Quaternary age. Rabilimis paramirabilis and R. septentrionalis apparently form an ancestor-descendant pair. They do not occur together in any deposits. R. paramirabilis occurs in Sumarine Beach (Beringian) at Nome, in the deeper levels of the offshore boreholes at Nome, and in the older levels of the Gubik Formation on the Arctic coastal plain of Alaska. Rabilimis septentrionalis occurs higher in the drill holes, higher in the Gubik Formation and in middle Pleistocene beds in the Kotzebue Sound area. Rabilimis septentrionalis is living today off the coast of Alaska, but it has not been collected south of Point Barrow. Foraminifera. Modern geographic distribution of foraminifera species reported as fossils in this paper are based on partly unpublished information of the Department of Oceanography, University of Washington, as well as on published information. Workers at the University of Washington have studied foraminifera from more than 1000 bottom-sediment samples from the shelves off northern and west.ern Alaska and northern and eastern Siberia. Geographic and stratigraphic occurrences of the Polymorphinidae are from Cushman and Ozawa (1930) supplemented by the literature cited below. Five species of this family were identified from our fossil material and of these only Globulina glacialis

FAUNA

IN

ALASKA

459

(Plate III, Fig. 6) has been found in modern sediments of the shelves off Alaska and Siberia. Sigmorphina undulosa (Plate III, Fig. 7) is widespread in Tertiary and Holocene sediments of the North Atlantic area and occurs in late Pleistocene sediments at, the shores of the Arctic Ocean in western Russia (Gudina and Evserov, 1973). Sigmomorphina sawanensis (Plate III, Fig. 8) is a Pliocene form from -Japan, but it may be still living off Labrador and Greenland. Photographs of specimens from the Greenland-Labrador region that Cushman (1948) identified as Guttulinu (Sigmoidina) pacifica (Cushman and Ozawa) strongly rcsemble S. sawanensis. Pseudopolymqhina ishikawaensis (Plate III, Fig. 3) occurs in the Pliocene of Japan and Alaska (Cushman, 1941) and P. ligua (Plate III, Fig. 4) is widespread in the European Tertiary. These two species are apparently extinct. Elphidium oregon.ense (Plate IV, Fig. 1) has been reported from off Oregon (Cushman, 1939), southern Alaska (Todd and Low, 1967), the northwest Pacific (Saidova, 1961), and southern Bering Sea (Loeblich and Tappan, 1953; Saidova, 1961; Anderson, 1963; Askren, Creager, and Echols, unpublished data, 1974). The most northern record in University of Washington material is from the north coast of St. Lawrence Island. Elphidkm oregonense is a fairly common fossil in Beringian beds at Nome (Cushman, 1941; R. Todd, written communication, 10/29!59; P. B. Smith, written communication, g/26,/61) ; it ranged northward into Kotzebue Sound during the Kotzebuan transgression (middle Pleistocene) (I’. B. Smith, written communication, g/25/61). To provide continuity with previous studies of foraminifera faunas from the Pleistocene of Alaska, Cushman’s (1941) concepts of Elphidiella, hannui and E. nitida are followed here even though they have been challenged by Bandy (1950). In Bandy’s opinion, the holotypes of E. han,nai and E. nitida are conspecific and appear to differ only because the holotype of E, han-

460

HOPKINS

ET

AL.

ANVILIAN

MARINE

nui is a worn specimen. If he is right, E. nitida Cushman (1941) is a junior synonym of E. hannai Cushman and Grant (1927) and E. hannai of Cushman (1941) and this report has been incorrectly named. Regardless of how this nomenclatural problem is eventually resolved, the biogeographic and biostratigraphic interpretations of this report will not be materially affected. These interpretations are based primarily on published papers where the species in question were figured and upon the personal experience of Echols with foraminiferal faunas from the Arctic and eastern Pacific. Only four individuals of EZphidieZlu hunnui (Plate IV, Fig. 3) were found in our fossil material. This species is a characteristic element of Beringian faunas from Nome (Cushman, 1941; Todd in Hopkins et al., 1960) and Kivalina (Todd in Hopkins and McNeil, 1960) but has not been reported from middle and late Pleistocene deposits of Nome and Kotsbue Sound (Todd in Hopkins et al., 1960; P. B. Smith, written communications, 11/16/61, 11/17/61, 11/22/61) nor from modern sediments of the Bering Sea or Arctic Ocean. It does occur in middle and late Pleistocene beds of western Siberia (Gudina, 1969 ; Gudina and Evserov, 1973) and modern sediments of the Okhotsk and Japan Seas (Saidova, 1961). Saidova identified this form as E. hunnai but Gudina (1969) named it E. tumida. If this species is not E. hunnai, for the reasons discussed here, its valid name may be E. tuntiida. --

FAUNA

IN

ALASKA

461

Elphidiella nitidu (Plate IV, Fig. 2a and 2b) is a common species of the inner sublittoral zone of the eastern Pacific from where it has usually been reported as E. hannui. Its modern geographic range is from 34ON off southern California (Resig, 1964) to the southeastern Bering Sea (Anderson, 1963; Loeblich and Tappan, 1953; Askren et al., n/IS). It has never been reported from modern sediments, nor does it occur in the Vniversity of Washington bottom samples, north of Xunivak Island, east-central Bering Sea. Fossil E. nitidu occurs in Beringian deposits at Nome and in Pelukian deposits of Kotzebue Sound (Cushman, 1941; P. B. Smith, written communication, g/25/61). We disagree with Todd and Low (1967) who placed E. nitidu into synonymy with E. groenlandica (Cushman), a species with an arctic distribution. Elphidiella sp. aff. E. sibiricu resembles immature E. sibirica, but none of the hundreds of individuals in our material approach the size and morphology of adult E. sibirica. Large examples are 1.4-1.6 mm in diameter and have 14-17 chambers in t,he last whorl. EZph~d~~~Zusibirica has a similar number of chambers at an int’ermediate stage in its ontogeny, but as au adult it ranges from 2 mm to more than 4 mm in diameter and has 20-25 chambers. In edge view, both immature and adult E. sibirica tend to be widest at the umboes, which are not protuberant, and the chambers tend to taper from them toward a moderately angular periphery. ,4 few of our E. sp. aff. E. sibirica approach this morphology .---.--~

------

PLATE III. Foraminifera from the California River and Killestok Creek outcrops. Figures 12 and 13 are scanning electron micrographs; all others are photomicrographs. Fig. 1. Dentnlina ittai Loeblich and Tappan. MF-1445, X40. Fig. 2. Oolina borealis Loeblich and Tappan; MF-1446, X40. Fig. 3. Pseudopolymorphina ishikawaensis Cushman and Osawa. MF-1446, x40. Fig. 4. Pseudopolymorphina ligua (Roemer) ; MF-1445, X28. Fig. 5. Glandulina laevignta d’orbigny; MF-1447, X40. Fig. 6. Globulina glacialis Cushman and Oeawa; MF-1447, X46. Fig. 7. Sigmomorphina undulosa (Terquem) ; MF-1447, X28. Fig. 8. Sigmomorphina sawanensis (Cushman and Ozawa) ; MF-1445, X28. Fig. 9. Nonio,neZZu miocenica Cushman. Sa, ventral view; 9b, dorsal view; 9c, peripheral view; M-1445, X40. Fig. 10. BuccelZu jri&da (Cushman). 1Oa. dorsal view; lob, ventral view; lOc, peripheral view; MF-1445, X40. Fig. 11. Gtoborotalia pachyderma (Ehrenberg); MF-1445, X55. Figs. 12 and 13. Cribrononion obscurus Gudina. 12. side view; 13, peripheral view; MF-1446, X23. Fig. 14. Cribrorlorlion incert~~ (W’illiamson) 14a, side view; 14b, peripheral view; MF-1445, X40.

._..-

462

HOPKINS

ET

AL.

ANVILIAN

MARINE

(Plate IV, Fig. 7) but most have Aat sides and a more rounded periphery (Plate IV, Figs. 8 and 9). Most of our examples of E. sp. aff. E. sibirica have very low umboes, but a few have protuberant umbona1 bosses. Elphidiella sp. aff. E. sibirica may be a new species or subspecies, but the differences from E. sibirica are minor and should be confirmed through study of populations from other localities before a new tnxon is named. We follow Russian workers [Orlov (ed.) , 19591 in placing in Cribrononion those forms formerly identified as Elphidium but having an optically granular wall. Both C. incertus (Plate III, Fig. 14) and C. obSCZLTUS(Plate III, Figs. 12 and 13) occur in University of Washington collections of modern foraminifera faunas from the northern Bering Sea. Our fossil C. incertus differs slightly from modern forms in having a somewhat depressed unbilical area. ;\‘onionella miocenica has been reported from Costa Rica to Wrangell, Alaska (Cushman and McCulloch, 1940), but neither it nor anything like it has ever been found in the Bering Sea or t,he Arctic Ocean. Only a single specimen of N. miocenica was found in the California River material (Plate III, Fig. 9), but its morphology is typical of recent forms of this species. Two specimens of Globorotalia pachyderma were found; both are right-coiling (Plate III, Fig. 11). We have not previously collected planktonic foraminifera in Quaternary sediments in the northern Bering Sea region, but they are common in cuttings from some of the offshore boreholes at nTomc, occurring there at stratigraphic

FAUYA

IN

ALASKA

463

levels that we consider to be of Pliocene age. Hopkins has also collected a single planktonic test from Submarine Beach at n’ome (P. B. Smith, written communications, g/26/61, 4/15/68). Age of the Fauna The California River fauna is quite different from the modern fauna of northern Bering Sea. Several taxa are extinct, and others are no longer living in t’he region. The fauna1 assemblage is generally similar to Beringian (Pliocene) and Anvilian (early Pleistocene) faunas of northwestern Alaska. Geomorphic relation with the 2.8 m.y. old lava flow (Fig. 5) show that t.he California River fauna cannot be older than late Pliocene. The molluscan assemblage includes t,wo taxa-Astarte diversa and C yclocardia crebricostata Tlomensis-that have been found only in deposits of the Beringian and Anrilian transgresslons and that seem to have become extinct before the middle Pleistocene Einahnuhtan transgression (Table 1). Astarte lefingwelli has been found at n’ome only in Beringian and Anvilian beds and does not occur in the rich molluvcan faunas of middle Pleistocene age from the northern Bering Sea and Kotzebue Sound regions (Pctrov, 1966; Hopkins, and Patton, 1972j, although Rowland, this ext,inct species apparently persisted along the coast of northern Alaska until the late Pleistocene (0. hl. Petrov, Geol. Inst., Acad. Sci. USSR, unpublished data, 1971 1. izl!~cl trrenaria seems to have berome extinct in the Sorth Pacific Ocean anIl in the Bcr-

PLATE IV. Foraminifera from the California River and Killestok Crrek outcrops. Figures 1, 2a, 5, and 9 are scanning electron micrographs; all others are photomicrographa. Fig. 1. Elphidium. oregonense Cushman and Grant; MF-1445, X27. Figs. 2a and 2b. Ekphidiella nitidu Cushman. Figures 2a and 2b are of different specimens. 2a, side view; MF-1445, X45. 2h, peripheral view; MF-1445, x41. Fig. 3. Elphidielln h~nai (Cushman and Grant). 3x, side view; 3b, peripheral view; MF-1445, X28. Fig. 4. Elphidium cluuutz~m Cushman; MF-1446, X41. Fig. 5. Elphidium subarcticurn Cushman; MF-1447, X39. Fig. 6. Protelphidiztm orbiculare (Brad,-). 63, side view; 6b, peripheral view; MF-1445, X41. Fig. 7. Elphidiella sp. aff. E. sibirica (Goes), umbonate form. 7a, side view; 7b, peripheral view; MF-1447, X28. Figs. 8 and 9. Elphidiella sp. aff. E. sibirica (Goes), typical form.

464

HOPKINS

ing Sea during the early part of the Pleistocene Epoch (MacNeil, 1965). The presence of Swiftopecten swiftii seems to be prima facie evidence for an Anvilian age. Although S. swiftii still lives today in northern Japanese waters, and although it was widely distributed in the northeastern Pacific during late Tertiary time (Masuda, 1972), it has been found previously in the Bering Sea region only in the type Anvilian at Nome. This distinctive pectinid has never turned up in deposits of Beringian age. The absence of Macoma balthica provides negative evidence favoring an early Pleistocene age. This bivalve appeared suddenly throughout northern waters in middle Pleistocene time (Spaink and Norton, 1967; Hopkins, Rowland, and Patton, 1972; Norton and Spaink, 1973), and it is the predominant mollusk in brackish-water faunas of Kotzebuan and post-Kotzebuan age (Table 1) in northwestern Alaska. If the California River fauna were of Kotzebuan or post-Kotzebaun age, we would expect M. balthica to be present along with the abundant Mytilus edulis and Littorina squalida, littoral and lagoonal species that are consistently associated with M. balthica in modern faunas from Bering Sea (Rowland, 1973). The rarity or perhaps total absence of Natica janthostoma in the California River fauna is surprising, as this distinctive snail is abundant in the fauna of Intermediate Beach at Nome. The pelecypod Astarte borealis arctica, on the other hand, has not previously been found in deposits as old as Anvilian. Nevertheless, the general aspect of the molluscan assemblage leaves little doubt that the California River fauna is of Anvilian age. The ostracode assemblage includes several taxa that no longer live in the northern Bering Sea. An Anvilian rather than a Beringian age is indicated by the presence of Rabilimis septentrionalis. This ostracode seems to have replaced the ancestral R. paramirabilis at about the beginning of the

ET

AL.

Pleistocene Epoch, and Beringian beds have yielded only the ancestral form (J. E. Hazel, written communication, 4/g/68). The foraminiferal assemblage, though consisting mostly of Arctic species, differs from any Arctic fauna within Echols’ experience by displaying a predominance of Cribrononion over Elphidium and by the common occurrence of large, robust polymorphinids such as Pseudopolymorphinia ishikawaensis and Sigmomorphina sawaenSiS.

Pseudopolymorphina

ishikawaensis

seems to be a Pliocene and early Pleistocene index fossil. It is common in Beringian beds at Nome; and it has not been found in sediments younger than Anvilian. Pseudopolymorphina ligua and Elphidiella sp. aff. E. sibirica may be extinct. Sigmomorphinia sawanensis seems to be extinct in the Pacific, though it may still be living in the North Atlantic. The taxon here called Elphidium hannai is a characteristic member of Beringian faunas but seems to have disappeared from the Bering and Chukchi Seas after the Anvilian transgression. The presence of planktonic foraminifers suggests considerable antiquity for the California River fauna. We have not previously collected planktonic foraminifera in Pleistocene or Holocene sediments in the northern Bering Sea region. The lack of tests of planktonic foraminifera in the modern sediment is probably a function of the great width and the shallow water depths of the Bering shelf. Different conditions-possibly deeper water-evidently favored survival of planktonic foraminifers nearer to the north coast of Bering Sea during Pliocene and earliest Pleistocene time. That our two tests of Globigerina pachyderma are both right-coiling is tantalizing. Modern populations of G. pachyderma in southern Bering Sea (the region from which our specimens must have been derived) are some 97% left-coiling, and right-coiling tests have not been abundant there since the Jaramillo geomagnetic polarity event about 1 m.y.a. (Echols, 1973). If our sam-

ANVILIAN

MARINE

ple population were larger, a predominance of right-coiling tests would provide strong evidence that the Anvilian transgression took place more than a million years ago, as Hopkins (1967: 63-65) has suggested earlier. Paleoecological Implications

and Biogeographical

The California River fauna consists mostly of species that now live on the inner shelf on a sandy silt substrate (Rowland, 1973). The foraminiferal assemblage suggests that salinity may have been moderately low, but the bottom water was not truly brackish. The abundant Myti1u.s edulis and Littorina spp. represent a littoral and possibly more brackish assemblage such as one might find in the intertidal zone near a river mouth. The fauna contains a curious mixture of Pacific, Arctic, and Atlantic species in addition to the numerous taxa that are still native to northern Bering Sea. The presence of several southern species in the Anvilian fauna of Intermediate Beach at Nome led Dal1 (1920)) MacNeil, Mertie, and Pilsbry (1943)) and Hopkins (1967) to assume that the northern Bering Sea was much warmer during Anvilian time than at present. The presence in the Anvilian fauna at California River of both mollusks and foraminifers that reach northern limits farther south in the Bering Sea or even in the Pacific Ocean at first seemed to us to support this assumption, but consideration of the small ostracode fauna points to quite a different conclusion. None of the six ostracode taxa identified to species level ranges south of Bering Sea,, and four are now restricted to high arctic waters. Two Anvilian mollusks must also be regarded as arctic endemics: Astarte lefingwelli ranged southward into northern Bering Sea during the Beringian and Anvilian transgressions but later became restricted to the Chukchi and Beaufort Seas, persisting there into late Pleistocene time; and Intermediate Beach at Nome has yielded the earliest Pacific

FAUNA

IS

ALASKA

165

record of Portlandia arctica (MacNeil, Mertie, and Pilsbry, 1943), a circumarctic mollusk that, except for a relict population off the Yukon Delta (Rowland, 1973), is now confined to waters north of Bering Strait. Some taxa in the California River fauna, notably S:c*iftopecten szriftii, M!/a arenaria, Natica jnnthostoma, and Hemicythere borealis. the form that v’e call Elphidielln hannai, Sigmom,orphina and probably saujanensis, have undergone drastic range reductions since early Pleistocene time, disappearing from large areas, yet persisting elsewhere at the same latitudes. Elimination of these taxa from northern Bering Sea may have resulted from competitive ex&sion or loss of ecotypes from the spccics gene pool rather than from changes in water temperature. are Paleotemperature interpretations further complicated by the fact that some of the extralimital species in the Anvilian fauna at California River and Nomc are rcprcsentcd by only one or two specimens (i.e., Portland&x arctica, Littorina sitkana, L. sp. cf. obtusata). These may be individuals that arrived from north or south as pelagic larvae during years of exccl)t’ionally cold or warm water rather than parts of established breeding ptipulations. Zinsmeister (1974) proposes this explanation for the well-known anomalous mixtures of cold- and warm-water mollusks in the Pleistocene faunas of southern California. Because of these considerations, wc believe it necessary to base our paleotemperature estimate upon species that are strongly represented in the fossil fauna and that do not seem t’o have undergone anomalous range reductions. Based on the joint occurrence of several strongly represented species that reach their northern limits in ccntral or northern Bering Sea (Pododusmus ma.croschi.sma, Elphidiuln oregonense, and Elphidiella nitida) toget,her with the strongly arctic-oriented ostracode f:luna, we conclude that water temperatures along the south coast of Seward Peninsula during

466

HOPKINS

Anvilian time differed little from those of the present time. Some of the peculiarities of the Anvilian faunas at Nome and California River may reflect either quickened north-flowing currents or deeper water on the Bering Shelf. Circulation in eastern Bering Sea is dominated today by the Alaskan Coastal Water, a mass of relatively warm water of moderate salinity moving in a brisk northerly current that accelerates to high velocities approaching Bering Strait (Coachman and Aagard, 1966). The moderate salinities suggested by the foraminiferal assemblage and the presence of planktonic foraminifers suggests that water circulation was northerly during Anvilian time, just as at present. Northward drift of planktonic foraminifers to the Bering Strait area would be facilitated by deeper water, which would permit the existence of established populations farther north on the southern Bering Shelf. Relative sea level may well have been higher during the Anvilian transgression. As crustal deformation has clearly affected the position of early and middle Pleistocene shorelines throughout the Bering Sea region, no firm conclusion can be drawn concerning the position of Anvilian sea level. Nevertheless, the common occurrence of high pre-Pelukian shorelines, some of them demonstrably of early Pleistocene age (Hopkins, 1967), suggests that water was deeper on the Bering Shelf during the Anvilian transgression. We conclude that circulation was dominantly northerly through Bering Strait during the Anvilian transgression. Relative sea level was probably higher and water deeper on the Bering shelf. Within the limits of discrimination of our data, water temperatures did not differ from temperatures of the present time. COMPARISON WITH THE CASSITERITE PEAK LOCALITY A few fossi molIusks have been found on the York Terrace near Cassiterite Peak

ET

AL.

(M1732, Fig. 3) in a geomorphic setting reminiscent of the California River locality. The Cassiterite Peak assemblage however, includes a specimen of Neptunea heros hews, a mollusk that seems to be an unambiguous indicator of a middle or late Quaternary age (Hopkins, 1967). The Cassiterite Peak fauna consists of mollusk shells found scattered on the terrace surface next to, and apparently derived from, firmly cemented beach gravel. The fossils were found about 400 m seaward from the inner edge of the York Terrace at an altitude of about 175 m (C. L. Sainsbury, written communication, 1963 ; Sainsbury, 1967). The beach gravel at the Cassiterite Peak locality lies on an apparently unglaciated segment of the terrace surface between lateral moraines of the Nome River Glaciation to the east and the west (Fig. 3). Several similar bodies of cemented beach gravel lie at the inner edge of the York Terrace, farther west. One of these is enclosed within the margins of a morainal loop of Nome River age. The scoured appearance of the gravel and its preservation within the glaciated area suggests that it had become cemented prior to the Nome River Glaciation This may be evidence that the gravel is considerably older than the Nome River Glaciation, but one must concede that detrital sediment can become cemented rather quickly in this limestone terrane. Sainsbury collected the following fauna: Gastropods Epitonium greenlandicum Perry) Polinices pallidus (Broderip

and Sowerby) Natica clausa (Broderip

Rare and

Sowerby)

Rare

Liomesius ooides canaliculatus (Dall) Colus spitxbergensis (Reeve) Neptunea heros heros (Gray)

Pelcypods Unidentifiable

Rare

fragments

Common Rare Very rare Rare

ANVILIAN

MARINE

All of the species in the small Cassiterite Peak assemblage live in northern Bering Sea at the present time. Polinices pallidus and Natica clausa are also a part of the Anvilian fauna at California River (Table 2). Epitonium greenlandicum and Colus spitxbergensis have been found in Beringian deposits, but not yet in beds of Anvilian age. Liomesus ooides (Plate II, Fig. 14) has not been found in deposits older than middle Pleistocene in western or northern Alaska, but given its rarity as a fossil, its presence in the Cassiterite Peak fauna cannot be said to have biostratigraphic significance. The presence of the molluscan species named does not provide definitive age information, but the presence of the single shell of Neptunea heros heros seems to exclude the possibility of an early Pleistocene age for the Cassiterite Peak fauna. This whelk has always been endemic to the Bering, Chukchi, and Beaufort Seas. A recent review of the genus Neptunea by C. M. Nelson (1974) shows that N. heros heros is known only from deposits of middle and late Pleistocene age. Deposits of the Pliocene Beringian transgression and of the early Pleistocene Anvilian transgression contain the subspecies, Neptunea heros mesleri. Deposits of the middle Pleistocene Einahnuhtan transgression contain mixed populations of N. heros heros and N. heros mesleri, and Nelson has found a few individuals of N. heros mesleri with the much more common N. heros heros in deposits of the later middle Pleistocene Kotzebuan transgression. The specimen from the Cassiterite Peak fauna (Plate II, Fig. 15) is a complete and moderately well-preserved juvenile of N. heros heros (C. M. Nelson, written communication, 12/10/73). Its presence in the Cassiterite Peak fauna seems to provide definite evidence that the enclosing sediments were deposited later than the Anvilian transgression, but the stratigraphic and geomorphic relation indicate that the cemented beach gravel is older than the Nome River Glaciation. Evidently

FAUNA

IN

ALASKA

467

the beach gravel in the Cassiterite Peak locality was deposited during middle Pleistocene time, during either the Einahnuhtan or the Kotzebuan transgression. CONCLUSIONS The Bering Strait region probably was a tectonically quiet region during much of Tertiary time. Long-continued, slow erosion led to the development of a subaerial erosion surface, Collier’s Kugruk Plateau. Deformation and dissection of this upland surface may have been related to the submergence of the present-day continental shelf of the Bering and Chukchi Seas. In any case, the California River originated sometime well before the beginning of the Pleistocene Epoch as a dendritic drainage system that included Arctic Creek and the upper Agiapuk River. The drainage was disrupted around 2.8 m.y.a. by volcanism east of the present-day main stem of the California River. Arctic Creek was then diverted and the flow of another tributary reversed to form the present drainage basin of the upper Agiapuk River. During the early part of the Pleistocene Epoch, wave attack on the northern shore of the Bering Sea truncated the lava flows east of the California River, and the fossiliferous beds at California River were deposited at the inner margin of the York Terrace. Sea level was higher, but within the limits of discrimination permitted by our data, water temperatures were not detectably different from those of the present time. Study of t,he California River area suggests that two glaciations preceded the middle Pleistocene Nome River Glaciation rather than the one early Pleistocene glaciation that had been inferred (Hopkins and Leopold, 1960; Hopkins, 1967). The Skull Creek erratics were probably deposited during a glaciation that preceded the Anvilian transgression, and the California River area then seems to have been glaciated a second time, after the Anvilian transgression and before the Nome River Glaciation.

465

HOPKINS

The presence of an Anvilian fauna at the inner edge of the York Terrace at California River indicates that the beveling of the marine abrasion platform was largely completed by early Pleistocene time. However, the presence of a fauna apparently of middle Pleistocene age near the inner edge of the terrace below Cassiterite Peak would indicate that the abrasion platform remained low as late as the Einahnuhtan and possibly even as late as the Koteebuan transgression. The Lost River Terrace, carved into the face of the York Terrace during the Pelukian (Sangamon) transgression, is hardly deformed. Most of the deformation of the York Terrace thus seems to have taken place late in middle Pleistocene time, but prior to the Sangamon Interglaciation. Sainsbury (1967a) has stressed that deformation of the York Terrace reflects active tectonism in the Bering Strait region and that this tectonism may have affected the timing of development of land bridges and seaways there. Flint (1971: 766-768) shows that few new mammal genera appeared in North America during the Nebraskan Glaciation, but the beginning of the Irvingtonian Mammal Age during the Kansan Glaciation was marked by a large influx. Several papers given at the All-L’nion Symposium on the Bering Land Bridge and Its Significance for the Distribution of the Holarctic Flora and Fauna during the

Cenozoic (Khabarovsk, Siberia, May 1973) confirmed that biotic exchanges across the land bridge underwent a long interruption during early Pleistocene time. Perhaps the exchanges of land biota were inhibited by prolonged submergence prior to the uplift that resulted in the deformation of the York Terrace. ACKNOWLEDGMENTS This report could not have been written without the earlier studies and the field guidance of C. L. Sainsbury. Robert E. Nelson provided invaluable assistance during the 1973 field work and dur-

ET

AI,.

ing the following autumn, when he prepared the microfossils described in this report. We are grateful to Joseph Rosewater (U.S. National Museum), Clifford M. Nelson (then at University of California, Berkeley, and now at the U.S. National Museum), and Louie N. Marincovich (then at Texaco and now at U.S. Geological Survey, Menlo Park, California) for their assistance in determining certain mollusks. Plates I and II are the work of Kenji Sakamoto of the U.S. Geological Survey. Unpublished foraminiferal determinations by Ruth Todd, Doris Low, and the late Patsy B. Smith were invaluable. We thank G. Brent Dalrymple, Marvin Lanphere, and Jarel C. Von Essen for providing us on short notice with a potassium-argon age estimate for the basalt on the east side of California River valley. Warren 0. Addicott and Thomas D. Hamilton reviewed the report and offered many helpful suggestions.

REFERENCES R. C. (1973). Paleoecology of a Pleistocene invertebrate fauna from Amchitka Island, Aleutian Islands, Alaska. Pcdaeogeogruphy, Palueoclimatology, Palaeoecology 13, X-48. ANDERSON, G. J. (1963). Distribution patterns of recent foraminifera of the Bering Sea. Micropaleontology 9, 305-317. BANDY, 0. L. (1950). Some later Cenozoic foraminifera from Cape Blanco, Oregon. Journal of Paleontology 24, 269-281. COACHMAN, L. K., AND AAGARD, K. (1966). On the water exchange through Bering Strait. LimnoG ALLISON,

ogy and Oceanography 11,

44-59.

E. V. (1971). The northwest American Tellinidae. Veliger 14 (Suppl.), 63 p. COLLIER, A. J. (1902). A reconnaissance of the northwestern portion of Seward Peninsula, Alaska. U.S. Geological Survey Professional COAN,

Paper 2, 70 p. CUSHMAN,

miniferal

J. A. (1939). A monograph on the forafamily Nonionidae. U5. Geol. Survey

Prof. Paper -

191,

l-100.

Some fossil foraminifera from Alaska. Contributions of the Cushman Laboratory for Foraminiferal Research, 17, 33-38. (1948). Arctic Foraminifera. Cushman Laboratory Foraminiferal Research Special Publicztion 23, SO pp. (8 plates). CUSHMAN, J. A., AND MCCULLOCH, IRENE (1940). Some Nonionidae in the collections of the Allan Hancock Foundation. Allan Hancock Pacific Expedition 6, 145-178. CUSHMAN, J. A., AND OZAWA, Y. (1930). A monograph of the foraminiferal family Polymorphinidae, recent and fossil. U.S. National Museum Proceedings 77, 185 pp. (40 plates). (1941).

ANVILIAN

MARINE

DALL, W. H. (1920). Pliocene and Pleistocene fossils from the Arctic coast of Alaska and the auriferous beaches of Nome, Norton Sound, Alaska. US. Geological Survey Professional Paper

125-C,

l-37.

E~HoL~, R. J. (1973). Foraminifera, Leg 19, Deep Sea Drilling Project, In “Initial Reports of the Deep Sea Drilling Project” (J. S. Creager et al., Eds.) Vol. 19, pp. 721-735. U.S. Govt. Printing Office, Washington, DC, 913 pp. FLINT, R. F. (1971). “Glacial and Quaternary Geology.” John Wiley and Sons, 892 pp. GHIM, M. S., AND MCMANUS, D. A. (1970). A shallow seismic-profiling survey of the northern Bering Sea. Marine Geology 6, 293-320. GUDINA, V. I. (1969). Morskoi Pleistotsen Sibirskikh Ravnin, Foraminifery Eniseiskogo Severa. Akad. Nauk SSSR, Siberskoe Otdeleniye, Trudy Inst. Geologii GUDINA, V. I.,

i Geofiziki

63, l-80.

AND EVERSOV, U. Y. (1973). Stratigrafy i foraminifery Pleistotsena Kolskogo poluowtrova. Akad. Nauk SSR Sibirskoe Otdeleniye, Trudy Inst. Geologii i Geofiziki 175, 145 p. HANNA, G. D. (1970). Fossil diatoms from the Probilof Islands, Bering Sea, Alaska. California Academy 167-234.

of Science

Proceedings

4th

Series,

37,

HAZEL, J. E. (1967). Classification and distribution of the Recent Hemicytheridae and Trachyleberididae (Ostracoda) off northeastern North America. U.S. Geological Survey Professional Paper 564, 49 pp. HOPKINS, D. M. (1967). Quaternary marine transgressions in Alaska. In “The Bering Land Bridge.” (D. M. Hopkins, Ed.), pp. 121-143. Stanford University Press. (1972). The paleogeography and climatic history of Beringia during late Cenozoic time. lnternord

__

12,

121-150.

(1973). Sea level history in Beringia during the past 250,600 years. Quaternary Research 3,

520-540.

HOPKINS, D. M., AND MACNEIL, F. S. (1960). A marine fauna probably of late Pliocene age near Kivalinn, Alaska. In “Short Papers in the Biological Sciences.” U.S. Geological Survey Professional Paper 400-B, pp. B339-B342. HOPKINS, D. M., MACNEIL, F. S., AND LEOPOLD, E. B. (1960). The coastal plain at Nome, Alaska: a late Cenozoic type section for the Bering Strait region. International Geological Congress HOPKINS,

Report

XXI,

4, 46-57.

D. M., ROWLAND, R. W., AND PATTON, W. W., Jr. (1972). Middle Pleistocene mollusks from St. Lawrence Island and their significance for the paleo-oceanography of the Bering Sea. Quaternary Research 2, 119-134. KNOPF, ADOLPH (1910). The probable Tertiary

FAUNA

IN

ALASKA

land connection ica: University Geology,

469

between Asia and North Amer0) California Publications in

Bulletin

5,

413-420.

LOEBLICH, A. R., AND TAPPAN, HELEN (1953). Studies of Arctic foraminifera. Smithsonian Miscellaneous

Collection

121,

l-150.

MACNEIL, F. S. (1957). Cenozoic megafossils of northern Alaska. US. Geological Surzley Professional

Paper

294-C,

99-126.

-

(1965). Evolution and distribution of the genus A!lya and Tertiary migrations of Mollusca. U.S. Geological Survey Professional Paper 483-G, 51 pp. (1967). Cenozoic pectinids of Alaska, lceland, and other northern regions. U.S. Geological Survey Professional Paper 553, 57 per. MACNEIL, F. S., MEBTIE, J. B., JR., AND PILSBRY, H. A. (1943). Marine invertebrates in the buried beaches near Nome, Alaska. Journal of Paleontology 17, MACPHERSON,

69-96.

Elizabeth (1971). The marine mollusks of Arctic Canada. National Museum of Canada, Publication Biology and Oceanography 3, 149 pp. MARINCXJVICH,L. N., Jr. (1973). “Neogene to Recent Naticidae (Mollusca: Gastropoda) of the Eastern Pacific.” University of Southern C:rlifornia, Ph.D. thesis, 347 pp. MASUDA, KOPCHIRB (1972). Swiftopecten of the northern Pacific. Palaeontological Society of Japan Transactions and Proceedings 87, 39% 408.

NELSON, C. M. (1974). “Evolution of the Late Cenozoic Gastropod Neptunea (Gastropoda : Buccinncea) .” University of California, Berkeley, Ph.D. thesis. NORTON, P. E. P., .~ND SPAINK, G. (1973). The earliest occurrence of Macoma balthica CL.) :ts a fossil in the North Sea deposits. Malacologia 14,

33-37.

R. W. (1973). “The Benthic Fauna of the Northern Bering Sea.” University- of California, Davis, Ph.D. thesis, 209 pp. SAIDOVA, KH. M. (1961). Ekologiya foraminifer i paleogeografiya dalnevostochnykh Morei SSSR i severo-zapadnoi chasti Tikhogo Okeana. Akad. Nauk SSSR, Inst. Okeanologii, 232 pp, SAINSBURY, C. L. (1967a). Quaternary geology of western Seward Peninsula, Alaska. In “The Bering Land Bridge.” (D. M. Hopkins, Ed.), pp. 121-143. Stanford University Press. (196713). Upper Pleistocene features in the Bering Strait area. U.S. Geological Survey ProROWLAND,

fessional

-

Paper

575-D,

D203-D213.

(1972). Geologic map of the Teller Quadrangle, western Seward Peninsula, Alaska. US. Geological fhruey Miscellnneous Geologic Inventory

Map

I-685.

440

HOPKINS

SCHMOLL, H. DOBROVOLNY,

R., SZAB~, B. J., RWIN, M., AND E. (1972). Radiometric dating of marine shells from the Bootlegger Cove Clay, Anchorage area, Alaska. Geological Society of America Bulletin 83, 1197-1114. SELLMAN, P. V., AND BROWN, JERRY (1973). Stratigraphy and diagenesis of perennially frozen sediments in the Barrow, Alaska, region. In “Permafrost.” The North American Contribution to the Second International Conference, National Academy of Science Report, ISBN-O309-02115-4, pp. 171-181. SPAINR,

G.,

AND

NORTON,

P.

E.

P.

(1967).

The

stratigraphical range of Macoma baZthica (L.) (Bivalvia, Tellinacea) in the Pleistocene of the Netherlands and eastern England. Mededelingen Geologische Stichting 18, 39-44.

ET

At,.

Edward, AND CATHCART, S. H. (1922). Geology of the York tin deposits, Alaska: U.S. Geological Survey Bulletin 733, 130 pp. SWAIN, F. M. (1963). Pleistocene Ostracoda from the Gubik Formation, Arctic Coastal Plain, Alaska, Journal of Paleontology 37, 79-83. TODD, RUTH, AND Low, DAVIS (1967). Recent foraminifera from the Gulf of Alaska and southeastern Alaska. U.S. Geological Survey Professional Paper 533-A, 145. VOORTHUYSEN, J. H. VAN (1950). The quantitative distribution of Plio-Pleistocene foraminifera of a boring at the Hague (Netherlands). Mededeling Geologiscke Stichting 4, 3149. ZINSMEISTER, W. J. (1974). A new interpretation of thermally anomalous molluscan assemblages of the California Pleistocene. Journal oj Paleontology 48,84-94. STEIDTMAN,