Late Pleistocene 

I Marine Paleoecology 

· and Zoogeography in 

Central California 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 523-C 

Late Pleistocene 

Marine Paleoecology 

and Zoogeography in 

Central California 

By W. 0. ADDICOTI 

CONTRIBUTIONS TO PALEONTOLOGY 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 523-C 

Invertebrate assemblages analogous to the Aleutian 

molluscan province indicate a former cool-temperate 

marine climate 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1966 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEW ART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

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

Washington, D.C. 20402 - Price 35 cents (paper cover) 
CONTENTS 

Page 

Abstract __________________________________________ _ C1 Paleoecology-Continued 

Introduction ______________________________________ _ 2 Substratum ___________________________________ _ 

Acknowledgments __________________________________ _ 2 Marine hydroclimate ___________________________ _ 

Earlier studies _____________________________________ _ 2 Regional marine paleoclimate _______________________ _ 

Geologic setting ___________________________________ _ 3 Outer-coast biotope ____________________________ _ 

Point Afio Nuevo localities ______________________ _ 3 Protected-coast biotope _________________________ _ 

Santa Cruz localities ___________________________ _ 3 Zoogeography _____________________________________ _ 

Faunal composition ________________________________ _ 4 Modern molluscan provinces ____________________ _ 

Paleoecology ______________________________________ _ 6 Late Pleistocene molluscan provinces _____________ _ 

Mode of formation _____________________________ _ 6 Discussion ____________________________________ _ 

Probable size of late Pleistocene fauna ____________ _ 8 References ________________________________________ _ 

BathymetrY--------------------~--------------- 8 

ILLUSTRATIONS 

[Plates follow index] 

PLATE 1. Mollusks and coral. 

2. Mollusks. 

3. Mollusks and echinoid. 

4. Mollusks and barnacle. 

Page 

C9 

9 

11 

11 

13 

1.5 

16 

16 

17 

19 

Page 

FIGURE 1. Index map of Half Moon Bay-Monterey area, central California ________________________________ ----------- C3 

2. Index map of the Pacific coast showing places referred to in text__________________________________________ 7 

3. Average annual temperature at surface and at 100 feet in northeastern Pacific Ocean ____ -- ______ ------------ 10 

4. Modern shallow-water molluscan provinces of the northeastern Pacific Ocean ____________________ ----------- 12 

5. Modern and inferred late Pleistocene shallow-water marine climate _____________________________ ----------- 14 

6. Late Pleistocene shallow-water molluscan provinces---------------------------------~-------------------- 15 

TABLES 

Page 

T~BLE 1. Late Pleistocene larger invertebrates _____________________________________________________ -------------- C4 

I 2. Pleistocene mollusks from Point Afio Nuevo and Santa Cruz, California, listed by Arnold _____ --------------- 4 

3. Late Pleistocene Foraminiferida from Point Afio N euvo and Santa Cruz, California _____ -_------------------- 5 

4. Late Pleistocene Ostracoda from Point Afio N euvo, Calif_ ___________________________ --------------------- 5 

5. Mollusks not previously reported as fossiL ____________________________________________ ----------------- 6 

6. Modern bathymetric ranges of selected sublittoral mollusks __________________________ -_------------------- 8 

7. Mollusks from the southwestern Santa Cruz Mountains that are extralimitaL_______________________________ 9 

8. Southern mollusks in the upper Pleistocene Millerton Formation__________________________________________ 14 

9. Late Pleistocene invertebrates from three-quarters mile southwest of Bandon, Oreg _________ ----------------- 17 

10. Mollusks from central California to Oregon open-coast assemblages that are now restricted to the Aleutian molluscan 

province________________________________________________________________________________________ 18 

11. Pleistocene invertebrates from Willapa Bay, southwestern Washington_____________________________________ 19 

III 

CONTRIBUTIONS TO PALEONTOLOGY 

LATE PLEISTOCENE MARINE PALEOECOLOGY AND ZOOGEOGRAPHY 

IN CENTRAL CALIFORNIA 

By w. 0. ADDICOTT 

ABSTRACT 

Open-coast molluscan assemblages of late Pleistocene age from 

northwestern Baja California to Oregon can be grouped to 

represent three faunal provinces. T'he composition of these 

units differs significantly from that of modern shallow-water 

zoogeographic provinces of the near-shore northeastern Pacific 

Ocean area. Late Pleistocene invertebrates of the outer-coast 

biotope from central California to Oregon have modern ranges 

that overlap in the vicinity of southern British Columbia (lat 

48° N.). These assemblages represent the newly recognized 

Nuevan molluscan province named for the relatively large opencoast assemblages from Point Afio Nuevo, Calif. (lat 37.1 o N.). 

To the south, molluscan assemblages broadly comparable to those 

of the modern Oregonian province (lat 34.5°-48° N.) occur from 

Estero Bay (lat 35.5° N.) south to the Channel Islands (lat 34o 

N.). This faunal unit is referred to as the Cayucan province 

(restricted) . South of the Channel Islands mixed assemblages 

with both extralimital northern and southern mollusks characterize the open-coast biofacies of southern California and northwestern Baja California. This faunal unit has been named the 

Verdean molluscan province (Valentine, 1961). 

In the Santa Cruz-Point Afio Nuevo area of central California, 

the open-coast late Pleistocene biofacies is represented by 101 

larger invertebrate taxa, principally mollusks. Also represented 

are 27 taxa of Foraminiferida, the largest late Pleistocene 

assemblage known from the Pacific coast, and 18 species of 

ostracodes. 'The megafossils represent a fossil assemblage consisting of three principal elements: a rock-boring pelecypod· 

element, an epifaunal gastropod element, and a sandy infaunal 

pelecypod element. The mollusks inhabited a level-bottom inner 

sublittoral biotope consisting of a fine sand substratum with 

local rock protuberances. The fossil assemblages are comparable to Shelford's (1935) Macoma-Paphia and Str·ongylocentrotusA.ruobuccinum communities of the near-shore northeastern 

Pacific Ocean. Bathymetric data on living mollusks suggest 

maximum water depths of 15-20 fathoms; physical data suggest 

shallower depths, about 10-14 fathoms. Locally the fossil assemblages are preserved undisturbed. Usually they are reworked or transported, but evidence of significant mixing with 

representatives of other communities is lacking. Zoogeographic 

criteria suggest relatively cooler surface-water temperatures 

during the late Pleistocene interval represented by these deposit<;. T'here is a moderately large element of extralimital 

species that today range no farther south than the latitude of 

Puget Sound ( 48o N.). The foraminifers, with one exception, 

have comparable zoogeographic affinities. Former average 

surface-water temperatures of about 7.5°0 are suggested for the 

winter-early-spring period. This is ahout 4° lower than presentday temperatures. Yearly high temperatures during the 

late-summer-early-fall period may have averaged about 13°C, 

about zo lower than present-day temperatures. T'he late 

Pleistocene marine climate was cool temperate, whereas the 

modern climate is temperate. 

The relatively cooler late Pleistocene hydroclimate indicated 

by fossil assemblages from the lowes:t emergent terrace in the 

coastal area of central California to Oregon differs markedly 

from that in the southern California area, where contemporaneous fossil assemblages commonly contain both southward- and 

northward-ranging extralimital species. GreateT climatic extremes are required by the faunal distributions in southern 

California. They have been interpreted as occurring within 

the framework of a generally warmer marine climate because 

of the sizeable subtropical to tropical molluscan element. The 

outer-coast assemblages in the northe•rn part of the late Pleistocene Verdean province are bracketed, however, by assemblages 

of predominantly northern aspect in central California and in 

northern Baja California, suggesting that the near-shore marine 

climate of this part of the noDtheastern Pacific Ocean may have 

been somewhat cooler than at present. The more southern position of isotherms during the late Pleistocene in central California and Oregon refl~ts an overall cooling and relatively 

narrow range of temperature, perhaps due to proximity to glacial melt water. The cool-water aspect of the northwestern Baja 

California assemblages may be related to heightened seasonal 

upwelling as the presence of a few warm-water specimens seems 

to indicate a relatively broader range of temperatures than 

now prevails in that area. The cool-water aspect of some of 

the faunal units conflicts with relatively warm interglacial 

paleotemperature estimates from zoogeographic •and oxygen 

isotope studies of foraminifers from deep-water oceani·c cores, 

although these are generally from more equatorial areas of 

other oceans. 

The only significant protected-coast assemblages from the 

central California-Oregon area occur in the upper Pleistocene 

Millerton Formation of Tomales Bay (lat 38.2° N.). These 

assemblages contain extralimital southern species that suggest a warm-temperate hydroclimate. T'he deposits are difficult to relate to the open coastal area and may not be contemporaneous.. Population of this protected biotope by 

warm-limited southern mollusks with long larval stages might 

have occurred during winter months of northward~flowing 

near-shore currents provided water was sufficiently warm. 

C1 
C2 CONTRIBUTIONS TO PALEONTOLOGY 

INTRODUCTION 

Segments of the lowest emergent coastal terrace in 

central California, northern California, and southern 

Oregon contain scattered assemblages of shallow-water 

mollusks of late Pleistocene age. The faunal assemblages represent open-coast communities that differ 

significantly in composition and zoogeographic aspect 

from the modern invertebrate fauna of this part of the 

Pacific coast. The largest and perhaps most significant 

faunal assemblages are frmn the Point Afio NuevoSanta Cruz area of central California. The faunal assemblages mark the southern outpost of a heretofore 

unrecognized late Pleistocene molluscan province characterized by northern mollusks and foraminifers that 

are no longer living off the central California coast. 

Although the late Pleistocene fauna of the Point Afio 

Nuevo-Santa Cruz area was originally noted by Arnold 

( 1908), its occurrence has been generally overlooked in 

subsequent studies of Pleistocene mollusks of California, and the original faunal list recorded less than onethird the number of invertebrate taxa herein identified. 

The Pleistocene invertebrates from the central California-Oregon area differ compositionally from the 

well-known late Pleistocene assemblages that occur farther south along the coast-from Estero Bay, Calif. 

(lat 35.4° N.) to northwestern Baja California. In the 

northern part, from Estero Bay to the Santa Monica 

Mountains, molluscan assemblages are broadly comparable to the modern fauna but differ by having a few 

northern and southern species whose modern ranges do 

not quite include the fossil localities. Late Pleistocene 

assemblages south of the Santa Monica Mountains ' however, are characterized by an element of warmwater mollusks displa.ced far to the north of their 

modern distributional limits and at some localities by 

extralimital northern species. 

The purpose of this report is to enumerate the coolwater late Pleistocene assemblages of the central 

Ca~ifornia-Oregon area, in particular the largely undescribed fauna of the Point Afio Nuevo-Santa Cruz area. 

These new faunal data are used in discussion of paleoecologic interpretations and zoogeographic reconstruction 

of the shallow water, near-shore shelf invertebrate 

communities. Finally, a more refined definition of the 

late Pleistocene molluscan provinces of the southern 

California-Oregon area is outlined and contrasted with 

the distribution of similar modern molluscan provinces 

and marine climatic zones of the near-shore eastern 

Pacific Ocean. 

Collections from the Point Afio Nuevo and Santa 

Cruz localities were made during the period 1962-64. 

Specimens were collected individually as well as by both 

dry and wet screening at the outcrop. Bulk and 

screened samples were returned to the laboratory, where 

they were examined for microscopic mollusks, Foraminifera, and other minute organisms. 

ACKNOWLEDGMENTS 

I am indebted to Patsy B. Smith and J. E. Hazel of 

the U.S. Geological Survey for identification of the 

Foraminiferida and Ostracoda, respectively, and for 

data on their modern distribution. E. C. Allison, T. G. 

Gibson, J. 'G. Vedder, and J. W. Valentine read the 

manuscript and offered helpful suggestions and criticism. A. G. Smith, California Academy of Sciences, 

examined the chi tons, and James McLean of the Los 

Angeles County Museum identified some of the trochids. 

Thanks are due A. Myra J{een for permission to study 

Pleistocene and Recent material at Stanford University 

and for examination of vermitid mollusks. L. G. 

Hertlein granted access t.o the collections at the California Academy of Sciences that were used for comparative purposes. Jack Miller assisted in securing 

collections from Point Afio Nuevo and prepared much 

of the material from these areas. W. C. Bradley and 

Robert Curry helped collect material from the Santa 

Cruz and Point A:fio Nuevo localities. The specimens 

illustrated herein were photographed by Kenji Sakamoto of the U.S. Geological Survey. 

EARLIER STUDIES 

Mollusks regarded as Pleistocene by Ashley ( 1895, 

p. 349) were reported from the Santa Cruz area with 

the observation that "at places H aliotiB and some other 

shells are quite plentiful." Inasmuch as H aliotis is 

not present in Pleistocene collections from this area, 

it seems possible that Ashley's reference was to aboriginal kitchen midden accumulations, which usually contain abundant H aliotis and some of which appear to 

be stratified. 

Arnold's (1908, p. 355-356) list of 32 gastropods and 

pelecypods from Santa Cruz and Point A:fio Nuevo is 

the first definite record of Pleistocene marine invertebrates from this area. In a subsequent list (Arnold 

in Branner and otihers, 1909, p. 7) three taxa iden6fied 

only to genus were omitted. Several studies of the 

physical aspects of marine terraces of the southern 

Santa Cruz Mountains were summarized or referenced 

in Bradley's (1957) investigation of the 100-foot terrace near Santa Cruz. Brief mention of some of the 

burrowing pelecypods that occur in the terrace platform near Santa, Cruz was made by Bradley (1956) 

and Acldieott ( 1963-a). Assemblages from three localities in the Santa Cruz area were listed by Hoskins 

(1957). 
MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CENTRAL CALIFORNIA C3 

GEOLOGIC SE'ITING 

POINT ANO NUEVO LOCALITIES 

Pleistocene fossils occur at two localities near Point 

Afio Nuevo (fig. 1). The principal locality, M1690, is 

on the south side of the point, about 1 mile east-northeast 

of Afio Nuevo Island. A second locality, M2147, is on 

the north side of the point, about 2 miles north of Afio 

Nuevo Island. Both localities are about 1 mile offshore 

from the associated late Pleistocene shoreline. 

Many exposures of the terraee deposits consist of 

unfossiliferous fine sand. Fossiliferous deposits presumed to have initially blanketed the terrace platform 

apparently have been redistributed or removed from 

these areas by wave or current action. 

On the south side of Point Afio Nuevo the wave-cut 

platform is directly overlain by a stratum of fossiliferous sand and sandy gravel that reaches a maximun1 

thickness of 2-3 feet. In the vicinity of the fossil 

locality the terrace platform is cut into a massive siltstone unit characterized by blocky fracture and ironst~ined surfaces. These exposures were mapped as the 

Miocene Monterey Formation by Hall and others 

(1959). The bedrock surface is broken by numerous 

steeply inclined burrows containing large specimens of 

Pen-itella penita. Other pelecypods inhabiting poekets 

or burrows in the terrace platform are Zlrfaea pilsbryiJ, 

122° 

Ml691 

MONTEREY / I/_,./ 

/ 

BAY /t I I 11/// 

5 0 5 10 MILES 

l!'IGURE 1.-Map of Half Moon Bay-Monterey area, central California, showing location of late Pleistocene fossil localities. 

Saxidomus g·iganteus, and Protothaca staminea ruderata. The fossiliferous stratum is overlain, locally, by 

light-gray to tan fine sand. 

Much of the fossiliferous stratum at this locality is 

reworked. Evidence of reworking is furnished by 

abundant nonarticula;ted pelecypod valves, a large percentage of broken or abraded shell material, and crude 

sorting. Reworked parts usually consist of rounded to 

subangular rock fragments and sand. Areas of undisturbed marine deposits are identified by abundant articulated valves of M acmna inquinata and Saxidomus 

nuttalli oriented in their normal living positions. There 

are also many specimens of the near-surface or nestling 

pelecypod Protothaca staminea with articulated valves. 

The undisturbed areas consist of gray fine micaceous 

sand. 

The fossiliferous stratum gains altitude eastward 

from locality M1690 to a point about three-quarters of 

a mile east of this locality, beyond which the terrace is 

truneated by a gravel-filled stream channel graded to a 

lowered sea level. Large articulated valves of Saxidomus or Tresus are visible from the beach near the eastern 

limit of the fossiliferous stratum, but the fossiliferous 

bed is inaccessible owing to near-vertical sea cliffs. 

North of Point Afio Nuevo, the terrace platform dips 

under the beach but reappears nearly 2 miles to the 

north near Green Oaks Creek where it is about 10-15 

feet above sea level. It is carved out of sandstone of 

the Pliocene Purisima Formation. Large areas of the 

platform have been swept clean of sediment, and its 

surface is extensively pitted with holes of boring 

pelecypods, many of which still contain valves of large 

P enitella. penita. Collections from this area are principally from burrows, but a few additional specimens 

were obtained from local exposures of reworked fine 

fossiliferous sand (loc. M2147). 

SANTA CRUZ LOCALITIES 

Pleistocene mollusks occur in sea cliffs along a halfmile segment of shoreline just west of Point Santa 

Cruz (fig. 1). Many of the mollusks in this area are 

boring or nestling species that occur in the terrace platform or in water-worn boulders lying directly above the 

platform. The principal locality in this area, M1691, 

is near the top of a sea cliff at the outer edge of an 

incipient sea stack. Aceess is hazardous. The terrace 

surfaee here is about 15 feet above sea level. It is eut 

into fossiliferous sandstone of the Pliocene Purisima 

Formation. The rock-boring faunal element is dominated by Platyodon cancellatus. A radioearbon date 

on peleeypod shells from this area reported by Bradley 

( 1956) was older than 39,000 years. 

Original sand deposits are preserved at loeality 

M1691 as pockets underneath and between large, rather 
C4 CONTRIBUTIONS TO PALEONTOLOGY 

flat boulders of calcareous sandstone--probably concretions weathered out of the underlying Purisima 

Formation. Although many specimens show evidence 

of abrasion, there are local areas where articulated 

valves of 8awidorntts gt'ganteus, Tresus nuttalli, and 

Protothaca stamJnea are obviously in place. 

FAUNAL COMPOSITION 

The late Pleistocene fauna of the southwestern Santa 

Cruz Mountains area includes at least 101 larger invertebrate taxa (table 1). Mollusks are the dominant 

faunal element. Gastropods are nearly three times a..s 

numerous as pelecypods. Most of the mollusks identified herein are figured on plates 1-4. 

TABLE 1.-Late Plei8tocene larger inverteb.rates from Point Aiio 

Nuevo and Santa Ct·uz, Calif. 

[USGS Cenozoic locality: cf., similar form, specimen(s) incomplete or too poorly 

preserved for definite identification; ?, doubtful identification; sp., species not determined; FI, field identificationl 

Gastropods Acmaea sp ________________________________________________ _ 

Lepeta concentrica (Middendorff) (pl. 3, figs. 7, 9) _________ _ Diodora aspera (Eschscholtz in Rathke) (pl. 2, figs. 4, 5) ___ _ .Megatebennus bimaculatus (Dall) (pl. 2, fig. 6) _____________ _ Puncturella galeata (Gould) (pl. 2, figs. 2, 3) _______________ _ Puncturella muUistriata Dall (pl. 2, figs. 7, 8) ______________ _ Calliostoma cf. C. doliarum Holten (pl. I, fig. 8) ___________ _ Calliostoma ligatum (Gould) (pl. 1, fig. 7) _________________ _ Lirulariafuniculata (Carpenter) (pl. 1, fig. 21) ____________ _ 

Lirularia lirulata conica (Carpenter) (pl. 2, figs. 20, 31) ____ _ Pupillaria pupilla (Gould) (pl. 2, fig. 21) __________________ _ Balcis cf. B. micans (Carpenter) (pl. 2, fig. 22) _____________ _ 

Epitonium indianorum (Carpenter) (pl. 2, fig. 29)---------- Lacuna carinata Gould (pl. 2, fig. 46) ______________________ _ 

Lacuna porrecta exaeqnata Carpenter (pl. 2, figs. 45, 47) ____ _ Lacuna solidnla compacta (Carpenter) (pl. 2, figs. 32, 37, 38) __ Alvania n. sp.? aff. A. ilinlinkensis Bartsch (pl. 2, figs. 35, 

36). Barleeia marmorea (Carpenter) (pl. 2, figs. 25, 34) _________ _ Fartulum occidentale Bartsch (pl. 1, fig. 27) ________________ _ Serpulorbis sp. (pl. 1, fig. 6) _______________________________ _ 

Bittium eschrichti (Middendorff) (pl. 2, figs. 12, 28) _______ _ Cerithiopsis cf. C. columna Carpenter (pl. 2, fig. 17) _______ _ Cerithiopsis paramoea Bartsch (pl. 2, fig. 43) _______________ _ Cerithiopsis rowelli Bartsch (pl. 2, fig. 18) __________________ _ Cerithiopsis cf. C. stejnegeri Bartsch (pl. 2, fig. 13) _________ _ Cerithiopsis n. sp.? aff. C. halia Bartsch (pl. 2, fig. 19) _____ _ Calyptraeafastigiata Gould (pl. 1, figs. 24, 28, 29) __________ _ Crepidula adunca Sowerby (pl. 3, figs. 5, 12) _______________ _ Crepidula nnmmaria Gould (pl. 1, figs. 3, 10) ______________ _ Trichotropsis cancellata (Duclos) (pl. 3, fig. 3) _____________ _ Trichotropsis cf. T. insignis Middendorff ___________________ _ 

Cryptonatica clausa (Broderip and Sower by) (pl. 1, fig. 13) __ Polinices sp. (pl. 1, fig. 14; pl. 2, fig. 1) ____________________ _ Velutina laevigata (Linne) (pl. 3, figs. 10, 11) _______________ _ 

Fusitriton oregonensis (Redfield) (pl. 1, figs. 11, 30, 32) _____ _ Ocenebra interfossa Carpenter (pl. 2, figs. 27, 50) ___________ _ Ocenebra cf. 0. lurida aspera (Baird) ______________________ _ 

Ocenebra luridamunda Dallin Williamson (pl. 1, figs. 17, 18) __ Ocenebra tennisculpta (Carpenter) (pl. 2, fig. 49) ___________ _ 

Trophonopsis multicostatus (Eschscholtz) (pl. 1, figs. 22, 23) __ Acanthina spirata (Blainville) (pl. 1, fig. 15) _______________ _ 

Thais canaliculata (Duclos) (pl. 1, fig. 9) ___ ---------------- Thais lamellosa (Gmelin) (pl. 1, figs. 1, 2, 4) _______________ _ Searlesia dira (Reeve) (pl. 2, fig. 51) _______________________ _ 

Amphissa columbiana Dall (pl. 1, fig. 5; pl. 2, fig. 23) _______ _ Mitrella carinata (Hinds) (pl. 2, fig. 10) ____________________ _ 

Afitrella carinata forma gausapata (Gould) (pl. 2, fig. 11) __ _ Mitrella gouldi (Carpenter) (pl. 2, fig. 14) _________________ _ 

Mitrella tnberosa (Carpenter) (pl. 2, fig. 9) ________________ _ 

Nassariusfossatt'S (Gould) (pl. 2, figs. 30, 48) ______________ _ 

Nassarius fossntus forma coiloteru.~ (Woodring) (pl. 1, fig. 

31). Nassarius mendicus (Gould) (pl. 1, fig. 12) ________________ _ 

Nassarius mendicus forma indisputabilis Oldroyd (pl. 1, 

fig. 16). 

Olivella biplicata (Sowerby) rpl. 3, fig. 17) ___ ·-------------- Olivella cf. 0. pedroanll (Conrad) (pl. 3, figs. 8, 20) _________ _ Oenopota? fidiwla (Gould) (pl. 1, fig. 20)_ _________________ _ Oenopota? tabulnta (Carpenter) (pl. 2, fig. 44) ______________ _ Dillphana brunnen Dall (pl. 2, fig. 33) _____________________ _ Iselica fenestrata (Carpenter)-~ ____________________________ _ Odostomia avellana Carpenter (pl. 2, fig. 41) ________________ _ Odostomia cf. 0. beringi Dall (pl.2, fie;. 39). _______________ _ Odostomia n. sp.? aff. 0. callimene Bartsch ________________ _ 

Odostomia cf. 0. columbiana Dall and Bartsch (pl. 2, fig. 40) _ 

USGS Cenozoic locality 

M1690 M1691 M2147 

X X X 

ef. X 

X X 

X X '!sp. cf. X X X X X X 

X X X 

X X X X 

X 

X 

X X X X X X X X 

X X cf. X X X 

X 

X ? 

X X X X 

X X X 

X X X 

X X X 

X X X X X X X 

X 

X X 

X cf. 

X X X 

X X X X 

X X 

X 

X 

X X 

X 

X 

X X 

X 

X 

TABLE 1.-Late Pleistocene larger invertebrates from Point Aiio 

Nuevo and Santa Cruz, Calif.-Continued 

Gastropods-Continued 

Odostomia 11tephensae Dall and Bartsch (pl. 2, fig. 42) ______ _ Odostomia tacomuensis Dall and Bartsch (pl. 2, fig. 26) ____ _ Odostomia cf. 0. tenuisculpta Carpenter (pl. 2, fig. 24) _____ _ Odostomia spp ____________________________________________ _ 

Cyclichna attonsa Carpenter (pl. 1, fig. 19) _________________ _ 

Pelecypods 

Adulacf. A. diEgensis (Dall) (pl. 4, fig. 14) ________________ _ 

Adula californien.Yis (Gould) ___ ---------------------------- Mytilus cf. M. edulis forma glomeratus Gould (pl. 3, fig. 4) __ Ostrea sp. (pl. 4,fig. 17) ___________________________________ _ 

Chlamys hericia (Gould) (pl. 4, fig. 4) _____________________ _ Chlamys pugetensis (Oldroyd) (pl. 4, fig. 5) ________________ _ Afysella cf. 1vf. tum.ida (Carpenter) (pl. 4, figs. 12, 13) ______ _ Clinocardium nuttalli (Conrad) (pl. 3, fig. 1) ______________ _ Trasenella tantilla (Gould) (pl. 2, figs. 15, 16) ______________ _ Saxidomus giganteus (Deshayes) (pl. 4, fig. 22) ____________ _ Protothaca staminea (Conrad) (pl. 4, fig. 15) _______________ _ 

Protothaca staminea forma ruderata (Deshayes) (pl. 4, 

fig. 21). Petric(!la carditoides (Conrad) (pl. 4, figs. 2, 3) _____________ _ Tresus capax (Gould) (pl. 3, fig. 21) _______________________ _ Tresus nuttalli (Conrad) (pl. 3, fig. 15) ____________________ _ Tellina bnttoni Dall (pl. 4, fig. 7) __________________________ _ 

Afacoma brota lipara Dall (reworked from Pliocene strata) 

(pl. 3, figs. 16, 19). Macoma expanl'a Carpenter (pl. 4, figs. 16, 19) _____________ _ l.Iacoma inquinata (De~hayes) (pl. 4, fig. 20) ______________ _ Siliqtta aff. S. patula Dixon (pl. 4, fig. 9)_ _________________ _ 

Afya truncata Linne (pl. 3, fig. 6)--------------------------- Cryptomya CIJ,lifornica Conrad (pl. 4, figs. 10, 11) ___________ _ 

Platyodon cancellatus Conrad (pl. 3, fig. 2) __ --------------- Hiatella sp_ ------------- __________ ------------- ___________ _ 

Zirfaea pilsbryi Lowe (pl. 4, fig. 18) __ ---------------------- Penitella penita (Conrad) (pl. 4, fig.1) ______________________ _ 

Chi tons 

Mopalia ciliata Sowerby (pl. 3, fig. 14) ____________________ _ l.fopalia cf. Af.lionosa (Gould) (pl. 3, fig. 13) _____________ _ 

Echinoid 

Strongylocentrotus sp. (plate,s, spines) (pl. 3, fig. 18) ________ _ 

Coral 

Balanophyllia elegans Verril (pl. 1, fig. 25, 26) ______________ _ 

Barnacles 

USGS Cenozoic locality 

MJ690 M1691 M2147 

X 

X 

X 

X X 

X 

X sp. 

FI 

X X X cf. 

X 

X 

X X X X X X X X X X 

X X X X X 

X 

X 

X 

X FI 

X X 

X X 

X 

X X 

X X 

X X 

X 

sp. 

X 

X 

? 

X 

FI 

X 

X 

X 

X 

X 

Balanus crenntus Bruguiere (pl. 4, fig. 6, 8)_________________ X cf. Balanus cf. B. nubilus Darwin_____________________________ X 

Balanus rostratus alaskensis Pilsbry________________________ X X cf. 

M1690. Sea-cliff exposure 1,100 ft south of road head and half a mile east-northeast of Point Aiio Nuevo. In projected T. 9 S., R. 4 W., Aiio Nuevo quadrangle 

San Mateo County, Calif. MI691. Narrow southern trending point 1,600 ft due west of Santa Cruz Point and, near SH cor. sec. 24, T. 11 S., R. 2 W., Santa Cruz quadrangle, 1954 ed., 

Santa Cruz County, Calif.- M2147. Sea-cliff exposure 900ft north of mouth of Green Oaks Creek, Franklin Point quadrangle, San Mateo County, Calif. 

TABLE 2.-Plei8focene mollu-sks from Point Aiio Nuevo and Santa 

Cr1"Z, Calif., li8ted by Arnold ( 1908, p. 35.5-356), not recognized 

in UHGS-M collection8 

Gastropods: 

Bittium rugatu.m Conrad 

Colutnbella. sp. a 

Fusus lu,teopictUif Dall 

Isapis sp. a 

M ang·ilia sp. a 

Margarita. paraipiota Carpenter 

Na.ssa perp·ingui8 Hunds [Hinds] 

Ocinebra. lurida var. a8pe1·a- Baird 

Oci.nebra lurida, var. oancellina Philippi 

Orinebm perfta, Hinds 

Odostomia nucifonnis Carpenter 

Phasianella oompta, Gould 

Splroglyphus Utuella Morch 

Pelecypods : 

M acoma nasuta. Conrad 

Pecten (H-innites) giganteus Gray 

Rupellaria lamellifera Conrad 

Saxidomus gracilis Gould 

The previously reported fauna from this area included 32 spe,cie.s, all mollusks (Arnold, 1908, p. 355-
MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CENTRAL CALIFORNIA C5 

356) . An attempt has been made to equate Arnold's 

identifications with those of this paper. Ta.xa reported 

by Arnold that could not be readily matched with the 

present faunal list are recorded in table 2.1 

Foraminifera constitute the next largest faunal element. Twenty-seven taxa have been identified from 

the Point Aiio Nuevo and Santa Cruz localities by Patsy 

B. Smith (table 3). This is the largest late Pleistocene 

TABLE 3.-Late Pleistocene Foram.iniferida from Point Aiio 

Nuevo and Santa Cruz, Calif. 

[Identified by Patsy B. Smith. Symbols: A, abundant; C, common; F, frequent; 

R, rare]. 

USGS Cenozoic Recent distribution 

localities in terrns of rnodern 

Species 

Astrononion gallowayi 

M1690 M1691 molluscan I provinces 

Loeblich and R Arctic to Oregonian. Tappan. Bolivina vaughani Natland_______________ R 

l'Juccella frigida (Cushman)_------------- F 

Buccella inusitata Anderson______________ C 

Buliminella cf. B. curta Cushman _______ _ Buliminella elegantissima (d'Orbigny)____ F Cassidulina teretis Tappan _____________ .__ F 

Cibicides lobatulus (Walker and Jacob) __ Dyocibicides biseralis Cushman and V alen- A tine. 

Elphidium bartletti Cushman_____________ A Elphidium orbiculare (Brady)____________ A f,Pisto'f!l,inella pacifica (Cushman)________ R 

zssunna sp_ ---------------------------- F Nodosaria emphysaocyta Loeblich and R 

Tappan. 

Nonionella cf. N. rniocenica Cushman____ R 

Nonionella basispinata (Cushman and 

Moyer). Oolina costata (Williamson) ______________ F 

Pateoris hauerinoides (Rhumbler)________ C 

Patellina corrugata Williamson___________ R 

Quinqueloculina sp_______________________ F 

Robertinoides charlottensis (Cushman)____ R 

Rosalina columbiensis (Cushman)________ F 

Spirilina vivipara Ehrenberg_____________ R 

Trichohyalus pustulatus Loeblich and A Tappan. 

F 

F 

R 

F 

F 

F 

A 

c 

R 

F 

R 

F 

R 

Oregonian to Panamic. 

Arctic to Oreg.•'1ian. 

Do. 

Arctic to Panamic. 

Arctic. 

Arctic to Panamic. 

Aleutian to Panamic. 

Arctic. 

Do. 

Arctic? to Panamic. 

Arctic. 

Aleutian to Panamic. 

Arctic to Panamic. 

Arctic. 

Arctic to Panamic. 

Arctic to Oregonian. Aleutian? 

Arctic to Panamic. 

Arctic to Aleutian. 

Uvigerina cf. U. peregrina Cushman______ F R Aleutian to Panamic. 

Globigerina bulloides d'Orbigny___________ F F Arctic to Panamic. 

Globigerina pachyderma (Ehrenberg)_____ R Arctic to Aleutian? 

1 Distribution determined from: Anderson (1961, 196[,), Bradshaw (1959) Cockbain 

(1963), Cooper (1964), Cushman (1925, 1948), Cushman and Todd (1947) Enbysk 

(1960), Green (1960), Lankford (1962), Loeblich and Tappan (1953) and Sn~ith (1963 

1964). See figure 4 for limits of molluscan provinces. ' ' 

foraminiferal faunule known from the Pacific coast. 

There are several species in common with the small late 

Pleistocene assemblage from Cape Blanco, southwestern 

pregon, described by Bandy ( 1950, p. 272) as the Rotalia tenerrima zone. Bandy's faunule consisted of 11 

species, including one considered to be reworked from 

older strata. 

Fifteen species of ostra.codes have boon identified 

from the Point Aiio Nuevo locality by J. E. Hazel (table 

4). Included are many undescribed species and subspecies. Some of these taxa have been found in collections from Recent localities along the Paeific coast by 

Hazel and R. H. Benson of the lJ.S. National Museum 

and, although undescribed, are nonetheless useful in 

paleoecologic and zoogeographic interpretation. According to Hazel (written commun., J nne 1965) there 

1 A search for Arnold's original collection from this area, at Stanford 

Univ., recovered only four species from his Afio Nuevo locality (loc. 

492) : Samidomus giganteus, Macoma inquinata, Lirularia sp., and Tha.is 

lamellosa. Additional material collected from this locality by Arnold 

is in the ?ollections at the U.S. Natl. Mus. (USGS loc. 7·336) ; ·included 

are : S. gtganteus, M. inquinata, Tresus capax, and Chlamys sp. 

are 11 ostracodes frmn the Santa Cruz locality. The 

assemblage is similar to the Point Aiio Nuevo material, 

although there are five additional genera represented by 

undetermined species: Oyprideis, O'ytheromorpha, 

Smnicytherura, Baird-ia, and Kangarina. The presence 

of Oyprideis and Oythermorpha suggests, to Hazel, 

either reduced salinity or, more likely, proximity to a 

lagoon or an estuary. 

TABLE 4.-Late Pleistocene Ostracoda from Poin-t Aiio Nuevo, 

Calif. 

[Identifications and distributional data from J. E. Hazel] 

Approximate 

latitudinal 

range or occurrence 

"Hemicythere" jollaensis LeRoy__________________ 32°- 48° 

Aurila? schumannensis (LeRoy)__________________ 32°- 48° 

"Paijenborchella" n. sp_________________________ 43°- 49° 

Ambostracon n. sp. aff. A. glaucum (Skogsberg)_____ 43°- 58° 

Hemicythere borealis (Brady) n. subsp _____________ 43°->48°? 

A urila n. sp. A 

A urila n. sp. B_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 47°- 49° 

Cythere sp _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 48° 

Pectocythere n. sp_ _ _ __ __ _ _ _ _ _ __ _ _ _ __ __ _ _ __ _ _ _ __ 48°- 68° 

"Pseudocythereis" n. sp __________________________________ _ 

Ambostracon palos ens is (LeRoy) n. subsp ___________________ _ 

H emicytherura sp _______________________________________ _ 

Sclerochilus sp. (rare) ____________________________________ _ 

Two species of undetermined generic affinity (both 

rare) ________________________________________________ _ 

Several small mollusks in the Santa Cruz-Point Aiio 

Nuevo fauna are here reported as fossil for the first 

time (table 5). Most of these are northern species that 

oecur no farther south than the Puget Sound area. 

Another species, Trichotropi.s cf. T. in8ignis, has not 

previously been reported from Cenozoic strata of California. Two taxa are not known to be living: Ocenebra 

tenu,iscru1pta and N a.ssarius fossatus forma coiloteru8. 

These gastropods have boon previously reported from 

the upper Pleistocene of the Los Angeles basin (Woodring and others, 1946; Addicott, 1965). Three 1ninute 

gastropods that are closely related to living species, 

Ali/Jania n. sp.? Odostomia n. sp. ?, and Oerithiops.Zs 

n. sp. ?, may also be extinct. Many other species including mollusks and foraminifers are locally extinct. They 

are refered to as extralimital species because their modern distribution does not include the Santa Cruz area. 

The significance of species that now live well to the 

north of central California is discussed subsequently. 

Specimens of JJJ aconw brota. lipara that occur at 

locality M1691 are reworked from the underlying 

Purisima F onnation of Pliocene age. They can be easily 

distinguished from autochthonous pelecypods by their 

unique bluish-white color. Also the original outline of 

the valves has been modified by extensive abrasion (pl. 

8, figs. 16, 19). A formaminifer identified as U'vigerina 

cf. U. peregri:na 1nay also be reworked from the Puris-
C6 CONTRIBUTIONS TO PALEONTOLOGY 

ima Formation, as its modern bathymetric range is 

generally much deeper than the associated foraminifers and mollusks would suggest. 

TABLE 5.-M ollusks not previously reported as fossil 

Gastropoda : 

Lirularia funiculata (Carpenter) 

Lirularia lirulata conioa (Carpenter) 

Lacuna porrecta e(J)aequata Carpenter 

Oerithiopsis cf. 0. columna Bartsch 

Oerithiopsis paramoea Bartsch 

Oerithiopsis rowelli Bartsch 

Oerithiop·siB ef. 0. stejnerueri Bartsch 

D·iaphana brunnea Dall 

Odostomia cf. 0. berin{fi Dall 

Odostomia stephon.sae Dan and Bartseh 

Odostomia tacomaensis Dall and Bartsch 

Pelecypods : 

Adula cf. A. dieuensis (Dall) 

Adula californiensis (Gould) 

PALEOECOLOGY 

Speculations on former environmental parameters 

such as bathymetry and temperature, deduced from 

biologic and physical evidence, are founded on the 

uniformitarianism princii>le of analogy with modern 

examples. Upper Pleistocene deposits clearly offer a 

favorable arena in which to interpret the fossil record 

in terms of modern distribution of marine life and 

physical properties of their environment. Some factors 

that permit a much greater degree of refinement in 

paleoecologic analysis of upper Pleistocene deposits 

than in older units are : ( 1) the brief time interval 

between genesis of the marine upper Pleistocene deposits and the present, possibly on the order of 100,000 

years,2 (2) the presumed contemporaneity or nearcontemporaneity of marine deposits of the lowest emergent terrace that can be identified for hundred of miles 

along the Pacific coast (Cooper, 1958 · Valentine and 

Lipps, 1963; Hoskins, 1957), (3) readily determinable 

depths of maximum inundation within the upper part 

of the inner sublittoral zone of Hedgpeth ( 1957), ( 4) 

the slight tectonic disturbance of deposits, ( 5) the presence of a closely analogous modern depositional environment in the near-shore segment of the submerged 

post-Wisconsin terrace along the Pacific coast, and ( 6) 

the excellent preservation and relatively large size of 

the. marine invertebrate fauna compared with prePlmstocene faunas at any given latitude. 

2 Uranium daughter-product ratios on aragcmitic shells from upper 

Pleistocene deposits at Santa Cruz have yielded age determinations of 

120,000±9,000 yr by the Th230-U238 method and 110,000±9,000 yr by 

the Ra226-U238 method (Blanchard, 1963). Radiometric dates on mollusks from the "100-foot" terrace in southern California based on 

uranium series disequilibrium include a maximum age of 130,000 yr 

for marine sediments on the Dume terrace of the western Santa Monica 

Mountains and a maximum age of 110,000 yr for the Palos Verdes 

Sand at San Pedro (Yerkes and Wentworth, 19651, p. 38-39). 

Of principal concern in paleoecologic study of the 

Santa Cruz assemblages is the shallow-water marine 

climate during deposition. Also of interest are the 

nature of the substrata of the late Pleistocene sea in this 

area and the bathymetry at specific localities. Whereas 

physical characteristics are useful in this respect, the 

fossil assemblage furnishes evidence upon which temperature speculations can be made. Although zoogeographic implications of the fauna are discussed in a 

subsequent section, some of the conclusions from the 

comparison of fossil and modern occurrences are important in the interpretation of marine paleotemperatures and are included here. Place names referred to 

hereafter are shown on an index map of the Pacific 

coast (fig. 2). 

MODE OF FORMATION 

An important step in paleoecologica! analysis is 

appraisal of the mode of formation (Johnson, 1960, 

1962) of individual fossil assemblages. Both biologic 

and physical criteria are pertinent to the determination 

of whether or not a given assemblage represents a transported accumulation (thanatocoenosis or death assemblage) and if so to what extent inhabitants of different 

biotopes have been brought together. 

Both the Point Afio Nuevo and Santa Cruz assemblages show evidenee of reworking of shell material such 

as abraded shells and abundant shell debris in the crudely sorted deposits. Yet some parts of these deposits 

have not been reworked. The undisturbed deposits are 

dominantly fine grained and mieaeeous and contain 

abundant articulated valves of several species of pelecypods. One species, Protothaca staminea, is very abundant at Santa Cruz. Its valves have remained so tightly 

closed that the interior is devoid of sediment. Most of 

the articulated pelecypods have ligaments preserved. 

Some still have patches of periostracum adhering to the 

shell. Further, some of the abundant infauna-such as 

the Saxidmn1ts, Tresus, and llf acoma-are oriented in 

their normal living position with the siphonal end of the 

articulated tests direeted upwards and the long axis of 

the shell normal to the bedding. These taxa are conspecific with some of the dominant mollusks in Shelford's 11-fa.coma-Paphia community (1935, p. 274), a 

shallow inner sublittoral level-bottom community of 

the Puget Sound area, Washington. The less abundant 

associated gastropod-barnacle-echinoid element seems 

closely comparable to his Strongylocentrotus-Argobuccinum community (p. 280), a hard-bottom sublittoral to upper bathyal community. Some of the Puget 

Sound species listed as dominants by Shelford ( 1935) 

that are represented in the outer-coast late Pleistocene 

assemblages of central California are M acoma inqu,inata, Protothaca staminea, Saxidomus giganteus, Tresus 
MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CENTRAL CALIFORNIA C7 

nuttalU, Strongylooentrotu.'3, FU.'3itriton oregonensis, 

Trichotropis cancellata, and Ohlamys hericia. 

<loo 

'?0 

...., 

"i:l 

~ 

C1 

~ 

~ 

~ 

.Jso C'l 

I 

I 

I 

I 

I 

1 4Qo 

j_ __ 

FIGURE 2.-Map of the Pacific coast showing places referred 

to in text. 

Successive communities of somewhat differing aspect 

inhabited the terrace platform and overlying sediments. 

Initial population of the fossiliferous localities occurred 

after the breaker zone of the rising sea passed inshore. 

An association of rock-boring pelecypods such as 

Platyodon and Penitella, nestling mollusks, and epifaunal elements probably dominated the biotope until 

the rocky surfaces became inundated by sand. In the 

succeeding life association, species boring and nestling 

in the platform surface were replaced by sand dwellers 

such as Sawidomus, Tresus, and Macoma. From all 

indications, the large invertebrate assemblages represent conditions that obtained during the stillstand of 

the sea during Pleistocene time. When the overlying 

water column was approximately 80 feet at the Afio 

Nuevo. localities on the basis of the occurrence of the 

shoreline angle at a present-day altitude of about 100 

feet (Bradley, 19·65) . 

During withdrawal of the sea from its maximum 

shoreline, these localities must have been subjected to 

the retreating zone of vigorous marine abrasion, a highenergy environment that extends down to about 30 feet 

below sea level (Dietz and Menard, 1951; Bradley, 

1958). Most exposures of terrace cover in the Santa 

Cruz area seem to have undergone extensive reworking. 

The occurrence of relatively undisturbed beds of marine 

fossils at some localities suggests that the late Pleistocene sea must have retreated rapidly from its highest 

reach. Under conditions of gradual retreat, the highenergy breaker zone probably would have destroyed 

all traces of the original inner sublittoral fossiliferous 

deposits. Some admixture of littoral invertebrates 

might also be expected under these circumstances. 

Clearly this is not the case. The undisturbed fossiliferous deposits at Santa Cruz underlie a protective 

ocean-bottom boulder field composed of concretions 

weathered out of the underlying Purisima Formation. 

At Point Afio Nuevo the reasons for their preservation 

are uncertain. Possibly the undisturbed sediments occupied slight depressions or pockets in the depositional 

surface or were overlain by moderate thicknesses of 

marine sediments, which acted as an effective buffer 

from the erosive action of the retreating surf zone. 

There is no suggestion of faunal mixing in the molluscan assemblages from the central California localities. Evidently the fine-sand-scattered rocky bottom 

substrata were sufficiently widespread on t_he surf-cut 

platform to preclude mixing with specimens from a 

different biotope. For example, none of the dominant 

species of Shelford's Pandora-Yoldia community 

(1935), an inner sublittoral muddy-bottom community 
C8 CONTRIBUTIONS TO PALEONTOLOGY 

associated with modern analogs of the late Pleistocene 

assemblages in the Puget Sound area, occur in the fossil collections. 

PROBABLE SIZE OF LATE PLEISTOCENE FAUNA 

Sampling of the late Pleistocene fauna at three localities near Santa Cruz has yielded 96 molluscan taxa. 

In a cmnprehensive study of the Recent mollusks of the 

Monterey Bay area, S1nith and Gordon (1948, p. 154--

155) recorded some 220 mollusks, "many of them gastropods" from "the shallow part of the neritic zone" 

( 5-40 fathoms). These were dredged from a substratum of fine dark sand containing scattered fragments 

of shale, presumably analogous to the late Pleistocene 

biotopes represented by the Santa Cruz and Point Afio 

Nuevo assemblages. The authors described a smaller 

group of 1nollusks (95) from a Miocene. shale reef biotope that occurs at depths of 8-40 fathoms in Monterey 

Bay. Allowing for some duplication of species in 

these two biotopes, a total assemblage of nearly 300 

species of 1nollusks is indicated for the middle and upper parts of the inner sublittoral zone of Monterey Bay 

and the surrounding area. The late Pleistocene collections may represent-, therefore, about one-third of the 

molluscan fauna that might have been ·present during 

the late Pleistocene. Comparison with the modern inner sublittoral fauna of Puget Sound would be n1ore 

meaningful, but comparable quantitative data are not 

available for that area . If such comparative data were 

available, a somewhat smaller late Pleistocene assemblage might be expected inasmuch as the invertebrate 

fauna of the Puget Sound-Queen Charlotte Islands 

area (Oldroyd, 1924) contains fewer shell-bearing molluscan taxa than that of the Monterey Bay area 

The combined fossil assemblages from ·the Santa 

Cruz area are somewhat smaller than the largest recorded ]ate Pleistocene assemblages referable to the exposed coast biofacies, a fauna of 153 mollusks from 

Point Lorna near San Diego, southern California (Valentine and Meade, 1961, p. 10-12), and a faunal assemblage of more than 150 taxa from San Nicolas 

Island (Vedder and Norris, 1963, p. 50). 3 

BATHYMETRY 

The composition of the larger invertebrate assemblages is indicative of the shallow part of the inner sublittoral zone ( 0-50 fathoms) of Hedgpeth ( 1957). Most 

of the species range from the intertidal zone down to 

20-25 fathoms. Some range even deeper. Yet there 

are several inner sublittoral species whose ranges seem 

3 There is a larger unrecorded open-coast assemblage consisting of 

about 240 species from Emerald Bay near Laguna Beach, Calif. (J. G. 

Vedder, oral commun., July 1965). 

TABLE 6.-M odern bathymetric ranges of seleoted sublittoral 

mollusks in the Point Aiio Nuevo and Santa Cru.z assemblages 

Species Bathymetric data and source 

Gastropods 

Lepeta concentrica (Midden- 10-60 fathoms (genus) (Coan in 

dorff). Keen, 1963, p. 101). 

Punctw·ella galeata (Gould) ____ 10-50 fathoms (Burch, 1946, no. 60, 

p. 28) ; 10-75 fathoms (Abbott, 

1954, p. 96) 0 

Puncturella multistriata Dan ____ 20-30 fathoms off San Juan Islands, 

Washington (Oldroyd, 1924, p. 

183). 

Balcis micans (Carpenter) ______ 5-25 fathoms, Monterey Bay area 

(Smith and Gordon, 1948). 

Trichotropis cancellata (Duclos)_ 15-2.5 fathoms, San Juan Islands 

(Oldroyd, 1924, p. 146) ; "Com• 

monly dredged in cold, shallow 

water" (Abbott, 1954, p. 168). 

Trichotrupis insignis Midden- "Dredged in Puget Sound off Friday 

dorft'. Harbor" (Burch, 1945, no. 54, 

p. 36) ; "Uncommon just offshore" (Abbott, 1954, p. 168). 

Fusitriton oregonensis (Red- 1~60 fathoms, Monterey Bay 

field). (Smith and Gordon, 194.8, p. 195), 

deeper than 75 fathoms off southern California, inshore in Puget 

Sound area (Valentine and Emerson, 1961, p. 617). 

Trophonopsis multicostatus 10-30 fathoms in Puget Sound, lit-

(Eschscholtz). toral in Alaska (Abbott, 195'4, p. 

207). 

Oylichna attonsa Carpenter _____ 10-40 fathoms, Monterey Bay 

Columbia (Quayle, 1960, p. 76). 

Pelecypod 

Mysella. tumida (Carpenter)____ 15-30 fathoms off California 

(Burch, 1945, no. 40, p. 15, 24) ; 

intertidal to 48 fathoms in British 

Columbia (Quayle, 1960, p. 76). 

to restrict the bathy1netric interval (table 6). These 

data indicate an overlap in the range of about 15-20 

fathoms. It is interesting to note that some of the 

northward-ranging species such as Fusitriton oregonensis and Oa.lyptrraea fa.stigiata are taken inshore or intertidally in the northern part of their range but submerge toward the south and are obtained only by 

dredging at middle sublittoral depths. The mollusks 

recorded from 10 fathoms and deeper off Monterey Bay, 

Calif., such as Oylichna attonsa, may also occur in 

shallower depths farther north. 

Foraminifera from localities M1690 and M1691 suggest an inner-continental-shelf environment with water 

depths probably less than 100 meters (Patsy B. Smith, 

written commun., November 1964). 

Ostracodes frmn locality M1691 at Santa Cruz indicate rather shallow inner sublittoral water depths according to J. E. Hazel (written commun., June 1965). 

The assemblage from Point Afio Nuevo, however, suggests somewhat deeper inner sublittoral or possibly 

outer sublittoral depths. 

Physical data tend to corroborate the depths suggested by faunal evidence. The difference in altitude 

of the wave-cut platform between the Santa Cruz and 

Afio Nuevo localities ( 15-20 ft) and the shoreline angle 
MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CENTRAL CALIFORNIA 09 

(about 95 ft and 100 ft, respectively, Bradley, 1965) 

is about 80-85 feet. This suggests maximum depths of 

about 13-14 fathoms. The gentle seaward downwarping of the Santa Cruz coastal area that followed the 

sculpturing of the lowest terrace (Alexander, 1953; 

Bradley, 1965) could account for somewhat shallower 

depths, possibly on the order of 10-11 fathoms. The 

·magnitude of seaward tilting of the lowest terrace averages about 10 feet per mile. These data, then, suggest 

somewhat shallower inner sublittoral depths than do 

the bathymetric range data. The abundance of mica 

in the undisturbed Pleistocene deposits is another feature that suggests middle inner sublittoral depths. 

Studies of recent sediments of Monterey Bay by Galliher (1932) indicate there is very little mica in the sediments between shore and depths of about 30-60 feet. 

Below these depths, however, mica is common; it is most 

abundant at depths of 120-180 feet. Bradley ( 1957, p. 

435) took samples which confirmed Galliher's observa-

.tions. 

SUBSTRATUM 

The composition of the fossil assemblages suggests 

that two substrata were present in the vicinity of the 

fossil localities : a hard, rocky substratum for rock 

borers and epifauna and a sandy bottom for the infauna, primarily pelecypods. A few other forms are 

ordinarily associated with 1narine algae or live commensally within other organisms. 

The fossiliferous deposits are about 1-3 feet thick. 

This is less than the relief on the lowest emergent late 

Pleistocene terrace platform at Santa Cruz, about 5 

feet (Bradley, 1957, p. 430). Relief on the analogous 

submerged terrace offshore from Santa Cruz may be as 

much as 10 feet (Bradley, 1957, p. 426). These differences suggest that rock protuberances may have extended above the thin cover of sand, providing refuge 

for rock-boring pelecypods, a substratum for the gastropod and barnacle epifauna, and attachment formarine algae. 

MARINE HYDROCLIMATE 

A significant feature of the central California fauna 

is the large representation of extralimital northern 

species of mollusks and foraminifers in the Point Afio 

Nuevo assemblage and, to a lesser extent, in the Santa 

Cruz asse1nblage. About 20 percent of the larger invertebrates has modern distributional patterns that are 

entirely north of the fossil locality. These species and 

their known ranges are listed in table 7. Three additional forms-Oerithiopsi.r.s cf. 0. columna, Thais lamellosa, and M acoma inquinata-are now living at or near 

their southern limit in the latitude of Santa Cruz. Of 

the more than 80 species of larger invertebrates for 

which distributional data are available, only 3 do not 

include the latitude of Puget Sound ( 48° N.) within 

their range. These species occur only north of the 

Puget Sound area (table 7). 

TABLE 7.-MoUu,sks from the southwestern Santa Cruz Mountains that are emtralimital with respect to their known modern 

distribtttion 

Species Modern latitudinal range 

j 38' 40° 42° 44_o 46° 48° 50° 52° 54° 56° 58° 60° 62° 64° 66° 

Gastropods: 

Lepeta concentr'ica (Middendorff) 1 ____________ I --~ Lirularia funiculata (Carpenter) ____________ I ·~ cf. L.lirulata conica (Carpenter) ___________ I ·~ Lacuna porrecta exaequata Carpenter ________ I •io 

Brittium eschrichti (Middendorff) ___________ 0 

tCerithiopsis paramoea Bartsch ______________ co •io 00 

cf. C. stejneger·i Bartsch __________________ Q) 

:e Trichotropis cancellata (Duclos)- ____________ ~ 

cf. T. z:ns·ignis MiddendorfL _______________ C) 

..s 

Oenopota? fidicula (Gould) _________________ ·-00 

tabulata (Carpenter )2 _____________________ 00 

0 

Diaphana brunnea Dall ____________________ """"' 

""""' 0 

Odostomia cf. 0. beringi Dall ________________ Q) •I- "0 

cf. 0. columbiana Dall and Bartsch _________ :::s 

..j..J 

stephensae Dall and Bartsch ______________ :p 

ro 

...::l ta.comaensis Dall and Bartsch _____________ I •IPelecypods: I Saxidom us giganteus (Des hayes) ____________ I Tresus capax (Gould) ____________________ -- I Macoma expansa. Carpenter _________________ I •IMya truncata Linne ________________________ I -1--1-

~ 
ClO CONTRIBUTIONS TO PALEONTOLOGY 

The Recent distribution of mollusks fron1. the central 

California localities then strongly suggests com parison with the modern fauna at the approximate latitude 

of Puget Sound, northwestern Washington. A minimum latitudinal shift of 11° in the range of certain 

mollusks since the late Pleistocene is thereby implied 

(table 7). As previously indicated, many of the dominant taxa from modern shallow-water inner sublittoral 

communities of the Puget Sound area (Shelford, 1935) 

are abundant in the central California assemblages. 

The modern distribution of the Foraminiferida from 

the marine terrace deposits tends to confirm the evidence for large postdepositional displacement of ranges 

to the north, and thereby suggests a former cooler 

marine hydroclimate. Four of the six foraminifers that 

are abundant or common in the Point Afio Nuevo sample (loc. M1690) are now restricted to either the "Arctic" or "Arctic-Aleutian" provinces according to data 

assembled by Patsy B. Smith (table 3). The two other 

commonly occurring species include these provinces 

within their range but also occur farther south. All the 

other species excepting Bolivina vaughani include at 

least part of the Aleutian subprovince (southern boundary 48° N.) within their range. Bolivina vaughani has 

been found living as far north as Bodega Bay, Calif., 

about 100 miles north of the Santa Cruz area (Lankford, 1962) ; recently specimens tentatively identified 

as B. vau:ghani have boon dregded off the Oregon coast 

(Gerald Fowler, oral commun., April1965). 

Ostracodes from the Point Afio Nuevo locality are 

also of northern aspect in terms of their present-day 

latitudinal distribution along the coast. Eight taxa for 

which distributional data are available have modern 

ranges that overlap in the vicinity of Puget Sound (lat 

48° N.) according to J. E. Hazel (written commun., 

June 1965). Two of the species have modern ranges 

that include the latitude of the fossil locality (37.1 ° N.), 

whereas the remainder are northern forms with southern endpoints between 43° and 48° N., several hundreds 

of miles to the north (table 4). Hazel emphasizes, 

however, that because the literature and available samples on Pacific coast ostracodes are relatively meager, 

zoogeographic inferences drawn from Recent distributions must be considered tentative. 

Surface and near-surface water temperatures in the 

vicinity of northern Washington and southern British 

Columbia are generally lower than those off central California in the vicinity of the fossil localities (U.S. Hydrog. Office, 1947; Robinson, 1957, fig. 38). Robinson's 

surface-,vater temperature charts of the northeastern 

Pacific Ocean for the period 1941-52 indicate an average annual inshore temperature differential of about 

3°C between Santa Cruz, Calif., and the Straits of Juan 

150° 135° 130° 

Light station and tide 60 o 

station averages 

50° 

48.1 s 

0 

t;: 

c 0 (j) 

() ::0 

J:> rn 

G) z 0 

z 

); 

z 40° 

60° 

50° 

40° 

150° 145° 140° 135° 130° 125° 120° 115° 110° 

FIGURE 3.-Average annual temperature, in degrees Fahrenheit, 

at surface (top) and at 100 feet (bottom) in the northeastern 

Pacific Ocean, 1941-52 (Robinson, 1957, fig. 3). 

de Fuca, Wash., in the low tide to 100-foot-depth range 

(fig. 3). If these data are representative of longer 

term temperature conditions, inshore surface-water 

temperatures near the southern boundary of the Aleutian molluscan province (lat 48° N.) average about 

13 oc in the warmest months (July-September) and 

about 71h o C in the coolest months (January-March) . 

Comparable maximums and minimums for central Cali-
MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CENTRAL CALIFORNIA Cll 

fornia in the vicinity of Santa Cruz (lat 37° N.) are 

15°C (August-October), and 11lh°C (DecemberApril). In this context, the data on modern distribution of shallow-water mollusks in the central California 

Pleistocene assemblages suggest average winter to early 

spring temperatures of about 71h °C, about 4° lower than 

present-day temperatures. The suggested average late 

summer to early fall temperature of about 13°C is about 

2° lower than present-day temperatures. 

The effect of depth on temperatures in the low-tideto-100-foot range in middle latitudes appears to be nil 

during the winter to early spring period (Bolin and 

Abbott, 1963; Robinson, 1957, fig. 50). In the warmest 

part of the year, however, a thermocline occurs at depths 

of 50-100 feet in the northeastern Pacific Ocean (Robinson, 1957, p. 68). Data on vertical temperature distri-

.bution in Monterey Bay (Bolin and Abbott, 1963, fig. 

2c) indicate that a difference of as much as 2°C may 

occur between the surface and a depth of about 15 fathoms during the summer months. In all probability, 

then, average maximum summer surface temperatures 

in the Pleistocene were somewhat higher than those at 

depths comparable to the fossil localities, 10-15 fathoms. 

REGIONAL MARINE PALEOCLIMATE 

It is necessary to utilize average values from the modern thermal regime in zoogeographic paleotemperature 

inferences. However, seasonal as well as long-terra 

cyclic temperature changes are often masked in charts 

of average maximum or minimum surface-water temperatures. Monthly sea-surface temperature charts for 

the northeastern Pacific Ocean (Robinson, 1957), for 

example, show a complex pattern of near-shore temperature distribution, yet the annual averages show a fairly 

simple pattern. Furthermore, the near-shore complexities are not at all predictable from the pattern of oceanic 

isotherms, which is generally alined in an east-west direction. Rarely do the oceanic isotherms intersect the 

shoreline of the northeastern Pacific Ocean perpendicularly. Assignment of discrete temperature values to 

fossil assemblages is particularly subjective; great care 

should be exercised in quantifying these phenomena. 

Large displacements of faunal units do seem meaning-

~ul, ho,vever, if they can be satisfactorily compared 

with modern faunal provinces. Such distributional 

shifts are characteristic of late Pleistocene molluscan 

assemblages from Oregon to Baja California. 

OUTER-COAST BIOTOPE 

The evidence from other occurrences of late Pleistocene invertebrates of the inner sublittoral exposed-coast I 

biotope from northern California and southern Oregon I 

suggests that cool water was not a local phenomenon .. 

Molluscan asse~blages from Crescent City ( Addicott, 

1963b), Cape lanco (Bandy, 1950; Addicott, 1964), 

and Bandon (t~ble 8) all contain extralimital northern 

species includi g significant representations of species 

now restricted o the Aleutian molluscan province of 

British Columb a and southern Alaska. 

The inferred ate Pleistocene occurrence of cool water 

far south of its odern southern limits along the margin 

of the northeas ern Pacific Ocean could be the manifestation of a unif, rmly cooler marine climate in this area 

or intensified pwelling in near-shore areas. The 

coastal segment from Point Conception to Washington 

is a present-day area of seasonal upwelling of cool water 

during the Iaten· inter, spring, and summer (Bolin and 

Abbott, 1963, p. 28). It is a well-known fact that local 

intensification f the upwelling process takes place on 

the south sides l~f some of the major points along the 

Pacific coast. frevailing north winds move surface 

water offshore, ~llowing cool water from below to rise 

to the surface. I The result is a strong temperature contra.st between t~e no:th and. south sides of principal 

pOints or cape~ during periods of strong northerly 

winds. Althoufh many of the cool-water Pleistocene 

assemblages oc~ur on or near modern points-Point 

A:No Nuevo, Cre cent City, and Cape Blanco-these features were not resent as such during deposition of the 

fossiliferous de osits. In the vicinity of these points, 

the late Pleisto .ene shorelines were relatively straight 

and were well i. shore from the fossil localities. Notwithstanding t e apparent geographic relationship to 

potential moder sites of intensified upwelling, it seems 

that the anoma ous southern occurrences of these coolwater assembla¢es are not the manifestation of local 

pockets of cool tater, because the requisite coastal configuration was t. ot developed near the late Pleistocene 

localities. 

Regional inte sification of seasonal upwelling characteristic of the 1 central and northern parts of the Oregonian mollusc~n province might produce a thermal 

regime in whichll a" much broader range of temperatures 

than now exist~ would occur, provided that temperatures returned tfnormal.levels during intervening periods. Under a broader spectrum of temperatures it 

would not be u reasonable to expect an invertebrate 

fauna that wou]d include some southward- and northward-ranging sJecies that do not now occur within the 

area. Clearly tJis is not the case with the faunal data 

from the area qonsidered herein. The zoogeographic 

unity of the cen}ral California-southern Oregon outercoast late Pleisjocene assemblages suggests, rather, a 

lmvering of bot:1 seasonal maximum and minimmn temperatures to vades comparable to those of the southern 

part of British 

1 

olumbia. 

I 
C12 CONTRIBUTIONS TO PALEONTOLOGY 

Although the interpretation of a cool near-shore 

water mass neatly fits the known data from central 

California and more northern open-coast assemblages, it 

is not compatible with the zoogeographic evidence from 

the outer-coast molluscan assemblages of southern California. The zoogeographic aspect of faunal data from 

south of the Channel Islands (lat 34° N.) is principally 

warm temperate to subtropical; however, there are extralimital northern species in some of these assemblages. 

The thermal regime of the southern California area was 

doubtlessly more complex than at present. Many 

workers have interpreted it as being generally warmer, 

but with local areas of more intense seasonal upwelling 

to account for the anomalous northern forms. A review of the southern California-northwestern Mexico 

late Pleistocene molluscan fauna and in particular some 

of the zoogeographic evidence suggestive of cool water 

in these areas seems appropriate. 

The occurrence of cool-water outer-coast molluscan 

assemblages in the San Diego and northwestern Baja 

California area is noteworthy. Open -coast localities 

from Point Lorna, Calif. (Webb, 1937), to Punta Baja, 

northwestern Baja California (Emerson and Addicott, 

1958; Valentine and Meade, 1961), contain several extralimital northern species. Molluscan assemblages 

from Punta Cabras (Addicott and Emerson, 1959) and 

Punta Baja contain a significant element of locally 

extinct northern species, about 20 percent. Warmwater species are poorly represented in the collections or 

absent. Modern distributional limits of the northern 

forms are within the modern Californian province (fig. 

4) . The number of significantly displaced species in 

these assemblages, northern mollusks now living in the 

Oregonian province (fig. 4), ·is very small. Although 

the faunal data do not indicate distributional shifts 

after late Pleistocene time as great as those in central California-Oregon assemblages, they do indicate 

relatively cooler marine climate than now exists in 

these areas. Valentine (1954) and Emerson (1956a) 

postulated that their occurrence in an otherwise 

warmer climatic framework was due to intensified 

seasonal upwelling in local near-shore areas. Presentday upwelling in these areas seems to account for 

similar, but less numerous, records of cool-water northern marine invertebrates nnd algae (Emerson, 1956a). 

Valentine and Meade's ( 1961, p. 41) paleotemperature 

determinations from oxygen isotope studies indicate 

that some of the southern species from exposed coast 

biotopes of southern California have isotopic temperatures far lower than would be predicted from their 

modern distribution. Instead, the temperatures are 

similar to values inferred from zoogeographic distribution of associated northern species. Some of the iso-

"-., 

~ 

~ I "-., 

<too 

<oo 

1\t ALEUTIAN 

(Columbian subprovince 

of Newell 0948)) 

OREGONIAN 

CALIFORNIA 

<too 

<oo 

FIGURE 4.-Modern shallow-water molluscan provinces of the 

northeastern Pacific Ocean. 
I 

MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CEN~RAL CALIFORNIA C13 

topic temperatures from southern forms in protected 

biotopes are also much lower than temperatures inferred from their modern distribution. 

A small Californian element reportedly occurs in late 

Pleistocene assemblages of the Gulf of California and 

the west coast of Mexico as far south as Oaxaca 

(Valentine, 1961, p. 393). These assemblages and 

the details of their occurrence are too poorly known, 

however, to determine whether they are contemporaneous with the late Pleistocene fauna of Baja California and farther north or to speculate on their 

climatic significance. 

The evidence of coiling-direction preference in the 

foraminifer Globigerina pachyderma in cores from the 

outlying basins in the southern California borderland 

may also be pertinent. Bandy (1960) presents evidence for a Pleistocene sinistral coiling population of 

this planktonic foraminifer succeeded about 11,000 

years ago, by a right-hand coiling population. Modern 

sinistral coiling in this species is limited to the cool 

waters of high latitudes (above 60° N.). The cool 

neritic hydroclimate suggested by the sinistral coiling 

Globigeri:na existed offshore from a near-shore area 

which was abundant faunal evidence of a late Pleistocene episode of marine climate that was at times warmer 

than at present.4 

To summarize, this area of warm inshore marine 

climate seems anomalous in the context of the unusually 

cool aspect of the central California-Oregon area to the 

north and the scattered suggestions of cooler climate in 

parts of northwestern Baja California. 5 In a larger 

sense, however, cool marine climate associated with interglacial high stands of the sea is unexpected and contrary to the zoogeographic and oxygen isotope studies 

pf planktonic foraminifers from the Pleistocene sequence in oceanic cores (Emiliani, 1955, 1961; Ericson 

[md Wollin, 1956). Possibly the relative southerly 

shift of surface isotherms in the central CaliforniaOregon area was a local cooling brought about by proximity to glacial melt water. The cool aspect of the 

northern Baja California assemblages more likely is 

related to intensified upwelling as the occasionally occurring extralimital southern mollusks in these assemblages would seem to be indicative of a relatively 

broader range of marine temperature. 

4 T'he projection of a uniformly cool oceanic climate much beyond 

the reach of radiocarbon dating is highly speculative. The basin cores 

may not have reached levels contemporaneous with the insular and 

inshore deposits of the lowest emergent marine terrace. 

s Average high and low surface temperatures inferred from data on 

fauna in central California, 13° and 7%°C, are considerably cooler 

than comparable figures on open-coast assemblages from southern California, about 20° and 11 oc (Valentine and Meade, 1961, p. 25, 32). 

Comparable temperatures of 14° and 11 °C were inferred for two opencoast assemblages in northwestern Baja California by Valentine and 

Meade (1961, p. 29). 

210-384 0-<616--3 

PIROTECTED-COAST BIOTOPE 

In the centra~ California-Oregon area, the protected 

bay or estuarin~ facies of late Pleistocene age are repre .. 

sented only in Jhe Tomales Bay 6 and San Pablo B~y 

areas. The m~ern distribution of faunal elements Irt 

the Tomales B y area suggests warm-temperate con-. 

ditions. Abou 25 perc~nt of the fossil mollusks of th~ 

Tomales Bay rea (Dickerson, 1922; Weaver, 194~, 

Valentine, 1961 ; Johnson, 1_962) occu~s north of their 

modern ranges. These species and their modern northern end-points of range are listed in table 8. Their 

former occurre ce at this latitude requires water temperatures abov those which now exist in this area. 

These assembla es seem to represent the modern Californian provin e (northern limit 34.5° N.), whereas 

open-coast asse blages near Santa Cruz several miles 

to the southeas are compositionally analogous to the 

fauna of the s~uthern part of the Aleutian province 

(southern bounHary 48 ° N. lat). The Californ~an and 

Aleutian provifces (fig. 5) may be characterized by 

warm-temperat~ and cool-temperate climates respectively (Hall, 1'64, p. 231). If the Millerton fauna 

is contemporan~ous with the outer-coast terrace assemblages, the ~pparent telescoping ~f the late Pl~istocene analogs qf the modern Californian and Aleutian 

provinces, withl the resultant absence of assemblages 

comparable to t~e intervening modern Oregonian province, suggests ~ much different thermal regi~e than 

now exists in tpis area. The known late Pleistocene 

distributions w 1uld thereby indicate lower near-surface 

temperatures in offshore, exposed coastal areas and a 

somewhat war er marine climate in protected bay environments. T is is not unlike conditions observed in 

southern Califo nia. There is an important difference, 

however; the ou r-coast assemblages, from Santa Cruz 

northward, do ot contain extralimital southern forms 

s The Millerton Fo mation of Tomales Bay, although possibly contemporaneous with t e marine upper Pleistocene terrace deposits elsewhere in California, s much thicker and more deformed. Attitudes of 

up to 10° (Dicker so~, 1922, p. 560) are recorded at the t~pe section, 

and exposures of th formation are said to be severely disturbed by 

faulting and landslid s (John~on, 1962) .. Dickerson (1922) ori~inally 

recognized two mart e formatiOns: the Millerton Formation of lower 

to middle Pleistocentage" (p. 559) and a flat-lying marine and nonmarine unit called th Tomales Formation said to uncoii_Iformably ov~rlie the gently inclin d strata of the Millerton Formation. Later Investigators have in luded both units in the Millerton Formation 

(Mason, 1934; Weaver, 1949). Unlike the open-coast localities, marine 

fossils are not restri¢ted to basal marine strata but occur throughout 

as much as 70 feet ofl section without apparent faunal change (Weaver, 

1949, p. 100-101) 0 t 

The structural defo mation of the beds presumably is related to their 

proximity to the adj cent San Andreas fault. (See Weaver, 1949, pl. 

9.) It seems unlikely that they could be as old as the lower Pleistocene 

part of the type Merct E'ormation, of late Pliocene and early Pleistocene 

age. The Merced (G en, 195•9, p. 157) contains a fauna suggestive of 

a bathymetric and de ositional environment comparable to that of the 

Millerton Formation; however, the faunal composition indicates cooltemperature, marine paleoclimate, unlike the warm-temperate aspect 

of the Millerton faun,. 
C14 CONTRIBUTIONS TO PALEONTOLOGY 

<too 

CALIFORNIA 

Plei;~Zene Modern 

~-------------N __ ea_r_-~s~.r_e __ m_a_r_in_e_c_l_im __ at_e __ ~----~<oo 

FIGURE 5.-Diagrammatic representation of modern and inferred late Pleistocene shallow-water marine clima,te of the 

near-shore northeastern Pacific Ocean. Late Pleistocene 

climatic boundaries after Valentine (1961), in part. 

TABLE 8.-So,uthern mollusks in the upper Pleistocene Millerton 

Formation 

[Occurrences from Dickerson (1922), Weaver (1949), Valentine (1961), and Johnson 

(1962)] 

Species 

Apolymetis biangulata (Carpenter) ____ _ Chione californiensis (Broderip) _______ _ Chione cf. C. undatella (Sowerby) _____ _ Chione undatella simillima Sower by ___ _ Corbula porcella (Dall) ________________ _ 

Glycymeris profunda DalL ------------- Laevicardium substriatum (Conrad) ____ _ 

Leptopecten latiauratus (Conrad) ______ _ Lucinisca nuttalli (Conrad) ___________ _ Protothaca lacinata (Carpenter) _______ _ 

Semele decisa Conrad ___ --------------- Trachycardium quadragenarium (Conrad). 

Crepidula onyx Sowerby --------------- Epitonium hindsi (Carpenter) (=E. 

tinctum (Carpenter)).' Nassarius delosi (Woodring) ___________ _ Shaskyus festivus (Hinds) _____________ _ Turcica caffea (Gabb) _________________ _ 

Modern northern limit of range (California) 

Point Conception (Fitch, 1953)_ Carpenteria (Fitch, 1953) ______ _ Goleta (Fitch, 1953) ___________ _ San Pedro (Parker, 1949) ______ _ 

Santa Rosa Island (Dall, 1921) _ Redondo Beach (Burch, 1944) __ Mugu, Ventura County (Burch, 

1944). Point Reyes (Grau, 1959) _____ _ Monterey (Burch, 1944) _______ _ Elkhorn Slough (Fitch, 1953) __ _ San Pedro (Burch, 1944) ______ _ 

Monterey Bay (Fitch, 1953) ___ _ 

Monterey (Burch, 1946) _______ _ Monterey (Palmer, 1958) ______ _ 

Balboa (Chace, 1962) __________ _ Morro Bay (Burch, 1945) ______ _ Monterey (Burch, 1946) _______ _ 

Distance 

from 

northern 

endpoint 

(miles) 

320 

380 

360 

460 

350 

460 

410 

20 

130 

130 

460 

130 

130 

110 

490 

260 

130 

1 Occurrence in upper Pleistocene sedimentary deposits of San Pablo Bay area (Weaver, 1949, p. 105). 

as do their southern California counterparts. The 

suspicion is, then, that although of late Pleistocene age, 

they may not be contemporaneous. 

The warm-temperate species in the protected coast 

assemblages of the Millerton Formation could represent a relict faunal element that might date back to 

early Pleistocene or late Pliocene time when water 

temperatures may have been somewhat warmer along 

the coastal areas. Another possibility is that southern 

species with pelagie larval stages of long duration 

could have been carried northward beyond their normal range by northward-flowing fall and winter surface 

currents-the Davidson Current Period of the annual 

marine climatic cycle off central California (Bolin and 

Abbott, 1963)-during an unusually warm cycle and 

become established in a suitably warm shallow-water 

biotope. 

The Pliocene or early Pleistocene relict hypothesis 

seems less plausible beeause most of the southern species 

(table 8) have not been reported from the late Pliocene 

and early Pleistocene Merced Formation (Martin, 

1916; Glen, 1959) of the San Francisco Bay area. The 

anomalous southern mollusks of the Millerton Formation more likely were carried northward by near-shore 

surface currents during the late Pleistocene and became 

established in warm shallow-water environments. A 

temporary invasion from the south is consistent with 

present knowledge of duration of pelagic larval stages. 

The modern oceanic cycle includes a period of strong 

northward-flowing currents near shore which are 

usually active from October to March along the central 

and northern California coast (Schwartzlose, 1963, 

p. 21) . These currents have minimal speeds of 0.5-0.9 

knots as measured by time elapsed between drift bottle 
MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CALIFORNIA C15 

releases and recoveries. If one assumes this speed and 

Thorson's 3-week average pelagic larval stage for 

marine mollusks (1957, p. 480), it is conceivable that 

mollusk larvae could be transported about 500-900 

miles. Reference to the relative displacement from 

modern end-points of range (table 8) shows that the 

maximum distance is about 560 miles, well within the 

theoretical boundaries suggested above. 

As indicated earlier, the population of Tomales Bay 

by southern forms may not have been contemporaneous 

with the open-coast biocenoses. The fauna of the Millerton Formation may have lived during a relatively 

warmer interglacial period temporally unrelated to the 

outer-coast marine terrace faunas-a possibility supported by the absence of warm-water forms from the 

relatively large open-coast faunas of central California 

and the overlap of modern ranges of their faunal constituents near the Straits of Juan de Fuca (lat 48° N.). 

Moreover, the characteristic northern species that are 

abundant in outer-coast late Pleistocene assemblages of 

the central California-Oregon area-such as M acoma 

inquinata, Tresus capaw, Samidomus g·iganteus, and 

M ya truncata-are not recorded from Johnson's Millerton localities (1962, locs. 1-4), which contain some 

open -coast species. 

ZOOGEOGRAPHY 

Studies of late Pleistocene molluscan.faunas of northwestern Mexico and southern California were initiated 

by Arnold's (1903) early study of the San Pedro Pleistocene. During the following 50 years or so, assemblages from many local areas in southern California 

were put on record. During the last decade increasing 

attention has been focused on interpreting late Pleistocene marine environments represented by the fossil 

assemblages and on the recognition of Pleistocene molluscan provinces. The abundant and well-preserved 

late Pleistocene mollusks of northwestern Baja California area and southern California have intrigued 

many workers. Notable among recent studies is the synthesis of the enormous amount of data from this area by 

Valentine (1961). Included in his geographic analysis 

was the recognition of three late Pleistocene molluscan 

provinces similar in some respects to the modern provinces that occur between Canada and northern Mexico 

(Valentine, 1961). These provinces (and the comparable modern molluscan provinces) are, from north 

to south: Cayucan (Oregonian), Verdean (Californian), and Magdalen an ( Panamic and northern 

overlap with the Californian province). (See figs. 4 

and 6.) 

<~oo 

s>oo 

/• 

I 

I

NUEVAN 

(northern boundary unknown) 

--+-+---+ ¢AYUCAN 

~restncted) 

1134°~ • I 

I 

~ERDEAN 

I 

MrDrNAN 

i 

EXrLANATION 

• 

Control 

• 

FIGURE 6.-Late 4 eistocene shallow-water molluscan provinces 

of the lowest e~posed marine terrace o~ Baja California to 

Oregon. After jvalentine (1961, fig. 9), m part. 
C16 CONTRIBUTIONS TO PALEONTOLOGY 

MODERN MOLLUSCAN PROVINCES 

Molluscan provinces of the near-shore northeastern 

Pacific Ocean (fig. 4) are defined as areas containing a 

characteristic 1

assembla.ge of species. Whereas faunal 

integrity characterizes the province, a rapid rate of 

change of fauna defines the boundaries (Newell, 1948, 

p. 159). Differences in marine climate are believed 

to be the basis of geographic differentiation of animal 

distributions. The boundary between the Californian 

and Oregonian provinces at Point Conception (lat 34.5° 

N.), for example, marks a significant change in inshore, 

near-surface marine temperatures. Superimposed 

upon the normal latitudinal temperature gradient are 

factors of current anomalies and upwelling in nearshore areas which greatly intensify the gradient in this 

area. The annual climatic eycle of the California coast 

north of Point Conception consists of three recognizable 

seasons : a late winter to late summer period of northerly 

winds and southward-flowing currents, a period of relative calm during the fall, and a brief winter period of 

southerly winds and northward-flowing eurrents (Bolin 

and Abbott, 1963, p. 28). South of Point Conception, 

however, ocean currents of the continental borderland 

are in an almost eontinual counterclockwise eddy, which 

seems to break down the normal southward-flowing 

eurrent operative off the central California coast 

throughout about two-thirds of the year. Studies of 

near-shore currents in this area by means of drift bottles 

( Sehwartzlose, 1963, p. 21) suggest that very little 

surface water passes from the near-shore southern California area into the region north of Point Conception. 

The periud of northerly winds off central California 

coincides with the onset of upwelling of cool water 

which tends to suppress near-shore surface temperatures 

during the first half of the year and thereby creates a 

strong gradient at either end of the upwelling belt, an 

area ·that extends from Point Coneeption northward as 

far as Oregon and Washington (Bolin and Abbott, 

1963, p. 43). For the Channel Islands area south of 

Point Conception, for example, Hubbs (1960, p. 110) 

reports a 10°C temperature gradient in summer seasurface temperature from the west end of San Miguel 

Island to the south side of Santa Cruz Island. 

A fairly strong gradient of decreasing annual surface-water temperature occurs along the northwestern 

coast of Washington (Robinson, 1957, fig. 38), and is 

most pronounced during the last half of the year 

(Robinson, 1957, figs. 8-30). This period coincides 

with the normal spawning season of many mollusks in 

that area (Quayle, 1960). The gradient may therefore 

act as a barrier to the southern dispersal of cold-limited 

species eharacteristic of the Aleutian province. 7 

Short-term changes in the climatic regime . of the 

area north of Point Conception that seem to be of a 

cyclic nature have been observed during a decade of 

careful monitoring of oceanographic conditions off central California (Bolin and Abbott, 1963). During these 

periods some unusual distributions of warm-water 

plankton have been observed in which species have been 

collected far north of their normal limits of distribution 

(Balech, 1960; Bernier, 1960). Similar unusually 

warm cycles could explain the presence of southern species in the late Pleistocene fauna of Tomales Bay. 

They might permit some southern warm-limited forms 

with relatively long larval stages to travel far north 

of their normal range, possibly during a period of relatively warm climate. Given access to a protected, 

shallow-water bay free from the influence of s~asonal 

upwelling which acts to depress yearly maximum 

temperatures, these southern species might be able to 

establish a reproducing population isolated by considerable distance from its distribution in the outer-coast 

biotope to the south. 

LATE PLEISTOCENE MOLLUSCAN PROVINCES 

Whereas the boundaries of Valentine's ( 1961) late 

Pleistocene molluscan provinces compare rather closely 

with those of modern provinces (figs. 4, 6), the composition of assemblages from comparable biotopes in each 

province differs significantly from that of their modern 

counterparts. Two seemingly distinct facies of shallow-water biota are involved. One represents a protected bay or estuarine biotope which, in California at 

least, includes many southern speeies with modern 

ranges that are displaeed to the south of the fossil 

oecurrences. The other is from an open- or e~posedcoast environment whieh, in southern California, commonly eontains a perplexing mixture of extralimital 

northern and southern species. 

The abundance of faunal data is such that the late 

Pleistocene analog of the Californian province (Verdean province of Valentine, 1961) is satisf~tctorily 

defined. It is doubtful that new data ean significantly 

modify its presently known boundaries or eomposition. 

Yet the southern and northern provinees are poorly 

1 Woodward (1856), Schenck and Keen (1936), Hall (11)64), and 

others consider this a separate and distinct province; Dall and Bartsch 

(1907) and Newell (1948) consider it part of the Oregonian. province. 

Aleutian is used herein to characterize the faunal unit of the Puget 

Sound-Queen Charlotte Island area as a matter of conv~nience in 

discussing conditions at its southern boundary (lat 48° 1!f.). Full 

provincial rank is not necessarily implied as it is perhaps doubtful 

considering Newell's (1948) analysis of range data. His name for 

this faunal unit (Columbian) seems, however, to be a syponym of 

Woodward's (1856) earlier-named Aleutian province. 
I 

MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CE~RAL CALIFORNIA C17 

defined, by comparison, because of the paucity of faunal First, it is assubed that virtually contemporaneous asdata. Valentine's definition (1958, 1961) of the north- semblages are bring lumped. The extensive coastal terern province, the Cayucan, was admittedly based on race tha,t occurf along the California coast at an altivery few and incomplete data. The Santa Cruz-Point tude of lesg tl~n 100 feet, as a rule, is believed to be 

Afio Nuevo fauna, not considered in his definition of the synchronous a d to represent a relatively higher stand 

Cayucan province, together with recently described of an eustatic ea level. There is ample evidence of 

open-coast assemblages of northern California and local and broa -scale warping of this marine surface, 

southern Oregon ( Addicott, 1963, 1964), provide a which locally c uses the shoreline angle to depart from 

better definition of the late Pleistocene molluscan dis- horizontal. N 1w techniques of radiometric dating 

tribution in this area. These newly considered faunal utilizing minute quantities of uranium and thorium in 

data modify, as will be subsequently shown, the original marine fossils told considerable promise in making reconcept of that province. fined correlatio of upper Pleistocene terrace deposits 

in tectonically active areas such as the Pacific coast. 

Second, the ass~mblages are closely comparable hathymetrically. Mlreover, modern depth ranges of these 

taxa do not ind' cate a pronounced distributional break 

within this bat ymetric interval. Third, the fossil deposits represent comparable substrata. At most places, 

they directly oferlie the bedrock surface and are composed of a thi* skin of sand or sandy gravel. Both 

infauna and !ifauna are usually represented, 'and 

thereby provid a broad base for recognizing fossil molluscan commullfities. Finally, classification of an assemblage as prd>tected or open coast, if not clearly determinable fuim faunal composition, can usually 

be checked by nalogy with modern shorelines, which 

usually mirror closely the late Pleistocene shorelines. 

DISCUSSION 

The known late Pleistocene faunal data of central 

and northern California. are from the Santa Maria 

basin, Santa Cruz, Point Afio Nuevo, San Francisco 

Bay, Tomales Bay, and Crescent City. Additional 

occurrences are known from Cape Blanco and Bandon, 

Oreg., and Bay Center, Wash. 

Open-coast assemblages from Santa Cruz, Point Afio 

Nuevo, Cape Blanco and Bandon (table 9) 8 are characterized by a persistent element of cool-water forms that 

now live far to the north. This element amounting to 

as much as 30 percent of one assemblage, is now almost 

entirely restricted to the Aleutian province of British 

Columl;>ia and southern Alaska (southern boundary lat 

48° N.). 

TABLE 9.-Late Pleistocene invertebrates from three-quarters 

of a mile southwest of Bandon., Oreg. ( OAS loc. 23) 

Gastropods: 

Lepeta concentrica (Middendorff) 

?P·upillaria sp. 

Orepidula cf. 0. grandis Middendorff 

Tric1wtropis cf. T. insignis Middendorff 

Fusinus sp. 

Thais lamellasa (Gmelin) (possibly Recent beach drift) 

Pelecypods : 

Mytilus cf. M. edulis forma glomeratus Gould 

Pododesmus macrochisma ( Deshayes) 

Transenella tantilla (Gould) 

Macoma cf. M. incongrua (von Martens) 

M acc;ma inquinata (Desha yes) 

M ya -truncata Linne 

Hiatella sp. 

Brachiopods : 

H emythiris sp. 

Terebratulina unguicula (Carpenter) 

Barnacle : Balanus sp. 

A review of some of the factors involved in synthesizing widely scattered occurrences of late Pleistocene 

invertebrates into faunal provinces seems appropriate. 

8 In addition to the collection at the California A·cademy of Sciences 

(table 9)~ there is a larger unrecorded collection at the University of 

California, Berkeley, that is being studied by V. A. Zullo. 

The souther~ faunas of the Santa Maria basin at 

Cayucos (Valeqtine, 1958) and near Point Sal (Woodring and Bra llette, 1950) do not contain representatives of the A eutian province. They contain only a 

very few specie that are not represented in the modern 

fauna of the so thernmost part of the modern Oregonian province ( alentine, 1958). Most of the extralimital forms ares Lthern species now restricted to the Californian mollusfan province. Although there are two 

northern forms! with present-day southern end points 

in the vicinity pf Monterey Bay in these assemblages, 

there is no evidence of the great latitudinal shifts of 

ranges such as ~ccur in the more northern late Pleistocene assemblag~s. 

If the Cayuc~· s fauna is comparable bathymetrically 

and ecologicall to the Santa Cruz and more northern 

exposed-coast f unas of northern California and southern Oregon, it surely does not represent the same 

province. It his none of the grea,tly displaced species 

of the Aleutian province which characterize the northern assemblage . Yet it seems to be distinct from the 

exposed -coast a semblages of the Los Angeles basin in 

that it lacks their characteristic element of warm water, 

Panamic mollus~s. These open-coast. assemblages represent a province of 

rather limited l~titudinal extent, from the Santa Monica 

I 

! 
C18 CONTRIBUTIONS TO PALEONTOLOGY 

Mountains (lat 34° N.) to a point between Oayucos 

(lat 35.5° N.) and Santa Cruz (lat 37° N.). The 

modern analog of this faunal unit is the Oregonian 

province (lat 34°-48° N.); Valentine (191

58) eharacterizes these assemblages as being almost purely 

Oregonian in aspect. As an alternative to treatment as 

a unique province, these assemblages could be regarded 

as a transitional faunal unit comparable to some of the 

known overlaps between modern molluscan provinces. 

The problematic warm-temperate fauna of the Millerton Formation was originally included in the Cayucan province as the only significant representative of 

the protected coast biofacies (Valentine, 1958). If this 

fauna is contemporaneous with the outer-coast terrace 

assemblages of the Santa Cruz area, an unusual juxtaposition of faunal elements from noncontiguous modern 

faunal provinces, the Aleutian (southern boundary lat 

48° N.) and the Californian (northern boundary lat 

34.5° N.) provinces, is indicated. Neither biofaeies is 

mixed as in some late Pleistocene assemblages from 

southern California where both Panamic and Oregonian 

forms frequently occur together (Woodring and others, 

1946; Valentine, 1955; Emerson, 1956b; Kan1akoff and 

Emerson, 1959) ._ 

New faunal data from the Santa Cruz area and other 

recently described assemblages from northern California and southern Oregon make it advisable to redefine the late Pleistocene molluscan province represented 

by open-coast assemblages from the Santa Cruz area 

northward to southern Oregon. At the time that the 

Cayucos assemblages were designated as being typical 

of this area (Valentine, 1958, 1961), the more northern 

assemblages were very poorly known. Subsequent investigations indicate that the Cayucos assemblages are 

not typical of the more northern area. It is therefore 

proposed that their use in characterizing the late Pleistocene molluscan assemblages to the north be discontinued and that the Santa Cruz and Point Aiio Nuevo 

assemblages, the largest and best known from the area, 

be adopted as the standard of reference for the late 

Pleistocene molluscan province lying north of the 

outer-coast assemblages of the Santa ~{aria and Santa 

Barbara-Ventura basins here included in the Cayucan 

province (restricted) . That province can take the 

substitute name N uevan for the Point A:fio Nuevo assemblage. Mollusks characteristic of this faunal province 

are: Lepeta concentric'a., Triclwtropis, Sawidmntt.rs giganteu,..rs, Tre8U8 capam, Ma.coma inquina.ta, and My~a 

truncata. The exclusively Aleutian species from the 

known open-coast assemblages of central California to 

southwestern Oregon are listed in table 10. They range 

from 8 percent of the molluscan assemblage at Crescent 

City to 31 percent at Bandon. 

TABLE 10.-Mollusks from central California to O.regon opencoast assemblages that are now restricted to the Aleutian 

molluscan province (southern boundary lat 48° N.) 

Santa Point Cape 

Cruz Afio Crescent Blanco Bandon 

(I at Neuvo City (lat (I at (lat 

36.9°) 

Gastropods 

Lepeta concentrica (Middendorf!') ___________ _ Lirulariajuniculata (Carpenter) ____________ _ 

Lirularia cf. L. lirulata conica 

(lat 

37.1°) 

X 

X 

41.8°) 

X 

42.8°) 

X 

X 

43.1 °) 

X 

(Carpenter)_______________________ X ---------- ---------- -------- -------- Lacuna porrecta exaequata Carpenter_________ X ---------- -------- -------- Crepidulacf. C. grandis Middendorff ___________________ ---------- -------- X 

Bittium eschrichti (Middendorf!')_____ X X ---------- -------- --------

g~~~}~~~l! grtr:e~}n~:,~s~hru-tsch~~ ~ ~========= ========== ======== ======== Trichotropis cf. T. insignis Middendorf!' _________________ ------------- -------- X ---------- ? X 

Oenopota? fidicula (Gould) ___________ -------- Oenopota? tabulata (Carpenter)______ X 

X ---------- X -------- X ---------- -------- -------- .Diaphana brunnea Dall______________ X ---------- ---------- -------- -------- Odostomia cf. 0. beringi Dall _________ -------- X ---------- -------- -------- Odostomia cf. 0. columbiana Dall and Bartsch _______________________ -------- X ---------- -------- -------- Odostomia stephensae Dall and Bartsch _______________ ------------ _______ _ X ---------- -------- -------- Odostomia tacomaensis Dall and 

Bartsch ___________________________ -------- X ---------- -------- --------

Odostomia talpa Dall and Bartsch __ ---------------------------- X --------

Pelecypods 

TotaL ____ --------------------- 6 13 1 6 4 

Molluscan taxa in assemblage _______ 57 70 13 37 13 

Percentage of Aleutian species in 

molluscan assemblage _____________ 11 19 8 16 31 

So few protected-coast assemblages are known from 

north of southern California that it is extremely difficult 

to characterize this biofacies. The Tomales Bay assemblages include some species now restricted to south 

of Point Conception (table 8). As mentioned earlier, 

it is convenient to think of these assemblages as more 

representative of the late Pleistocene Verdean province 

because of these Californian faunal elements. They 

may or may not be contemporaneous with the outer-coast 

' assemblages. If contemporaneous, a condition of overlap not unlike that at the modern Panamic-Californian 

province boundary (Emerson, 1956a, p. 329) is indicated. The only other known occurrence of this 

biofacies is a small faunule, presumably of comparable 

age, from Willapa Bay, southwestern Washingt?n 

(Kincaid, 1957). The assemblage consists of 1'2 species 

(table 11), all of which have modern geographic ranges 

that include the fossil locality. These species are common to both the modern Oregonian and Aleutian 

provinces. 

Many late Pleistocene fossil assemblages from the 

Puget Sound area, Washington, and from southwestern 

British Columbia have been successfully dated by the 

radiocarbon technique. The marine part of the lowest 

emergent terrace in California, however, has proven to 

be too old to be dated by this technique (Kulp and 

others, 1952; Bradley, 1956; Orr, 1960). Some upper 
MARINE PALEOECOLOGY AND ZOOGEOGRAPHY, CE~RAL CALIFORNIA C19 

TABLE 11.-Pleistocene invertebrates from Willap·a Bay, southwestern Washington (USGS Cenozoic loc. M149"1) 

Gastropod : Thais la.rnellosa ( Gmelin) 

Pelecypods : 

M ytilus edulis Linne 

Ostrea lurida Carpenter 

Olinocardium nuttalli (Conrad) 

Saxidomus giganteus (Deshayes) 

Protothaca staminea (Conrad) 

Tresus capax ( Gould) 

M acoma inquinata ( Deshayes) 

Macoma nas·uta (Conrad) 

Oryptornya californica Conrad 

Barnacle : Balanus crenatus Bruguiere 

Foraminifer : Elphidium sp. 

Pleistocene deposits in the Pacific Northwest, however, 

are older than the range of radiocarbon resolution, 

about 30,000-40,000 years, and could possibly ·he contemporaneou..: with the California and Oregon terrace 

deposits. They are the Nickomel Formation (Wagner, 

1959) of the Fraser River area, British Columbia, and 

the Cherry Point Silt (Easte~hrook, 1963, p. 1470) of 

northwestern Washington. Marine mollusks and 

barnacles occur in both units, but only the fauna of the 

Nickomel Formation is recorded. Assemblages from 

the Nickomel Formation suggest water depths of 

5-15 fathoms (Wagner, 1959, p. 50). The largest assemblages (loc. 7) contain 40 mollusks, all but one of 

which occur within their known modern range. The 

extralimital species, Odostomia sillana, is known only 

from the type locality in the Aleutian Islands. Wagner determined from the median of midpoints analysis 

(Schenck and Keen, 1937) that the latitude of the collection was 51° N. (the actual latitude of loc. 7 is 49.1° 

N.). This calculation was corrected, however, to a 

"corresponding present-day latitude" (Wagner, 1959, 

p. 44, 47) of 60.9° N. from a chart prepared by Schenck 

(1945). The reason for the correction was that the 

median of midpoints calculated for modern assemblages 

from British Columbia and Washington fail to agree 

with the actual midpoint by 2°-12° of latitude, the midpoints regularly plotting 2° or more farther south than 

the eollection. 9 

Clearly, the Nickomel fauna is closely comparable 

with that of the Aleutian province (lat 48°-56° N.) 

and is only slightly displaced, if displaced at all. It is 

a much cooler water assemblage than those from the 

Santa Cruz to Cape Blanco area of California and 

Oregon to the south. 

9 Although the Nickomel fauna may have lived in cooler water than 

currently exists at this latitude, the suggestion of conditions comparable with those about 10° farther to the north are at odds with 

the basic data. Of the ranges of 40 species known from Ioc. 7 (Wagner, 

1959, p. 8-9), 19, or nearly 50 percent, do not occur north of 60° N. 

in the modern fauna, and 40 percent. of the species occurs no farther 

north than 58•, about 200 miles south of the assumed: modern 

equivalent. 

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Institution Oceanography Bull., v. 7, no. 1, p. 1-98. 

Schenck, H. G., 1945, Geologic application of biometrical analysis 

of molluscan assemblages: Jour. Palentology, v. 19, no. 5, 

p. 504-521, pls. 66, 67. 

Schenck, H. G., and Keen, A. M., 1936, Marine molluscan provinches of western North Americ-a: Am. Philos. Soc. Proc., v. 

76, no. 6, p. 921-138. 

-.-- 1937, An index method of comparing molluscan faunules: 

Am. Philos. Soc. Proc., v. 77, no. 2, p. 161-182. 

Schwartzlose, R. A., 1963, Near shore currents of the western 

United States and Baja California as measured by drift 

bottles : California Coop. Oceanic Fisheries Inv. Repts., v. 

9, p. 15-22. 

Shelford, V. E., 1935, The major communities, in Some marine 

biotic communities of the Pacific coast of North America, 

Pt. 1: Ecol. Mon., v. 5, p. 251-292. 

Smith, A. G., and Gordon, Mackenzie, .Jr., 1948, The marine 

mollusks and brachiopods of Monterey Bay, California, and 

vicinity: California Acad. Sci. Proe., ser. 4, v 26. no. 8, 

p. 147-245, pls. 3, 4. 

Smith, P. B., 1963, Possible Pleistocene-Recent boundary in the 

Gulf of Alaska, based on benthonic Foraminifera, in Short 

I Valentine, J. W., and Meade, R. F., 1961, Californian Pleistocene 

paleotemperattres: California Univ., Dept. Geol. Sci. Bull., 

v. 40, no. 1, p 1-46. 

Valentine, J. W., nd Lipps, J. H., 1963, Late Cenozoic rocky 

shore assembl~ges from Anacapa Island, California : Jour. 

Paleontology, t· 37, p. 1292-1302. 

Vedder, J. G., and lNorris, R. M., 1963, Geology of San Nicolas 

Island, Califor1ia: U.S. Geol. Survey Prof. Paper 369, 65 p. 

Wagner, F. J. E., ~59, Paleoecology of the marine Pleistocene 

faunas of sou hwestern British Columbia: Canada Geol. 

Survey Bull. 5 , 67 p., 1 pl. 

Weaver, C. E., 194$, Geology of the Coast Ranges immediately 

north of the ~n Francisco Bay region, California : Geol. 

Soc. America em. 35, 242 p. 

Webb., R. W., 193 , Paleontology of the Pleistocene of Point 

L~ma, San Di~go County~ California: San Diego Soc. Nat. 

History Trans., v. 8, no. 24, p. 337-348. I 

Woodring, W. P .. fr-amlette, M. N., and Kew, W. S. W., 1946, 

Geology and J;aleontology of Palos Verdes Hills, California: U.S. Gtol. Survey Prof. Paper 207, 145 p., 37 pls. 

Woodring, W. P., and Bramlette, M. N., 1950, Geology and 

Paleontology of the Santa Maria district, California: U.S. 

Geol. Survey P~of. Paper 222, 185 p., 23 pls. 

Woodward, S. P., ~856, A manual of the Mollusca; or a rudimentary treati~e of recent and fossil shells: London, J. 

Weale, 486 p. I 

I 

Yerkes, R. F., and "fentworth, G. M., 1965, Structure. Quaternary 

history, and g1neral geology of the Corral Canyon area, 

Los Angeles County, California: U.S. Geol. Survey Rept., 

July 1965, preJared on behalf of the U.S. Atomic Energy 

Comm .. 215 p., app. A-D. 

PLATES l-4 
PLATE 1 

FIGURES 1, 2, 4. Thai~:, lamellosa ( Gmelin). 

1. Height 64 mm, width 38 mm. USNM 649222. Loc. M1690. 

2. Height 55 mm, width 33 mm. USNM 649223. Loc. M1690. 

4. Height 26.5 mm, width 15.9 mm. USNM 649224. Loc. M1691. 

3, 10. Crepidula nurnmaria Gould. 

3. Length 41.5 mm, width 31.5 mm. USNM 649225. Loc. M1691. 

10. Length 27.5 mm, width 23.5 mm, thickness 5.3 mm. USNM 649226. Loc. M1691. 

5. Amphissa columbiana Dall. Height 19.7 mm, width 9.6 mm. USNM 649227. Loc. M1691. 

6. Serpulorbis sp. Length (incomplete) 16.5 mm, width 5.7 mm. USNM 649228. Loc. M1690. 

7. Calliostorna ligaturn (Gould). N onapertural view of an incomplete specimen. Width 18.3 mm. USNM 

649229. Loc. M1691. 

8. Calliostoma cf. C. doliarium Holten. N onapertural view of an incomplete specimen. Width (incomplete) 14 

mm. USNM 649230. Loc. M1691. 

9. Thais canaliculata (Duclos). Height 8 mm, width 6.9 mm. USNM 649231. Loc. M1690. 

11, 30, 32. Fusitriton oregonensis (Redfield). 

11. Length (incomplete) 21 mm, width 18.5 mm. USNM 649232. Loc. M1690. 

30. Apertural view of an incomplete specimen. Width 36 mm. USNM 649233. Loc. M1690. 

32. Apertural view of an incomplete specimen. Height 91 mm. USNM 649234. Loc. M1690. 

12. Nassarius mendicus (Gould). Height 15 mm, width 8 mm. USNM 649235. Loc. M1690. 

13. Cryptonatica clausa (Broderip and Sowerby). Height 13.8 mm, width 12.8 mm. USNM 649236. Loc. M1690. 

14. Polinices sp. Height 13.3 mm, width (incomplete) 11.5 mm. USNM 649237. Loc. M1690. 

15. Acanthina spirata (Blainville). Height 23.6 mm, width 13 mm. USNM 649238. Loc. M1691. 

16. Nassarius mendicus forma indisputabilis Oldroyd. Height 17.6 mm, width 8.6 mm. USNM 649239. Loc. 

M1690. 

17, 18. Ocenebra lurida rnunda Dall in Williamson. Height 13.2 mm, width 6.9 mm. USNM 649240. Loc. M1690. 

19. Cylichna attonsa Carpenter. Height 10.5 mm, width 3.8 mm. USNM 649241. Loc. M1690. 

20. Oenopota? fidicula (Gould). Height 13.5 mm, width 5.1 mm. USNM 649242. Loc. M1690. 

21. Lirularia juniculata (Carpenter). Height 6 mm, width 5.7 mm. USNM 649243. Loc. M1690. 

22, 23. Trophonopsis rnulticostatus (Eschscholtz). Height 27.5 mm, width 8.7 mm. USNM 649244. Loc. M1690. 

24, 28, 29. Calyptraea jastigiata Gould. 

24, 28. Height 15.8 mm, width 32.5 mm. USNM 649245. Loc. M1690. 

29. Height 12.1 mm, width 27 mm. USNM 649246. Loc. M1690. 

25, 26. Balanophyllia elegans Verril. Height 9.4 mm, width 10.6 mm. USNM 649247. Loc. M1690. 

27. Fartulum occidentale Bartsch. Greatest length 2.5 mm, diameter of aperture 0.6 mm. USNM 649248. Loc. 

M1691. 

31. Nassarius jossatus forma coiloterus (Woodring). Height 57 mm, width 27 mm. USNM 649249. Loc. M1691. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 523-C PLATE 1 

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5 

' 2 

6 

10 12 13 14 

20 

15 16 17 18 19 

26 

25 

27 

PLEISTOCENE MOLLUSKS AND CORAL FROM CENTRAL CALIFORNIA 
FIGURE 1. 

2, 3. 

4, 5. 

6. 

7, 8. 

9. 

10. 

11. 

12,28. 

13. 

14. 

15, 16. 

17. 

18. 

19. 

20, 31. 

21. 

22. 

23. 

24. 

25, 34. 

26. 

27, 50. 

29. 

30, 48. 

32, 37, 38. 

PLATE 2 

Polinices sp. Height 15.5 mm, width 18.3 mm. USNM 649350. Loc. M1691. 

Pucturella galeata (Gould). Height 10.1 mm, length 15.5 mm, width 12 mm. USNM 649251. Loc. M1690. 

Diodora aspera (Eschscholtz in Rathke). Height 4.2 mm, length 12.6 mm, width 8 mm. USNM 649252. Loc. 

M1691. 

Megatebennus bimaculatus (Dall).. Height 2.9 mm, length 19.7 mm, width 12.3 mm. USNM 649253. Loc. 

M1691. 

Puncturella multistriata Dall. Height 8.6 mm, length 18.9 mm, width 14.4 mm. USNM 649254. Loc. M1690. 

Mitrella tuberosa (Carpenter). Height 7.3 mm, width 3.3 mm. USNM 649256. Loc. M1690. 

Mitrella carinata (Hinds) . Height 6.2 mm, width 3.3 mm. USNM 649257. Loc. M1691. 

Mitrella carinata forma gausapata (Gould). Height 6.8 mm, 3.4 mm. USNM 649258. Loc. M1691. 

Bittium eschrichti (Middendorff). 

12. Immature specimen. Height 3.1 mm, width 1.7 mm. USNM 649259. Loc. M1691. 

28. Height 11.3 mm, width 4.4 mm. USNM 649260. Loc. M1690. 

Cerithiopsis cf. C. stejnegeri Bartsch. H eight 3.6 mm, width 1.6 mm. USNM 649261. Loc. M1691. 

Mitrella gouldi (Carpenter). Height 11.8 mm, width 6.7 mm. USNM 649262. Loc. M1690. 

Transenella tantilla (Gould). Length 8.2 mm, height 7.3 mm. USNM 649263. Loc. M1690. 

Cerithiopsis cf. C. columna Carpenter. Incomplete specimen, width 2.8 mm. USNM 649264. Loc. M1690. 

Cerithiopsis rowelli Bartsch. H eight 2.8 mm, width 1.2 mm. USNM 649265. Loc. M1690. 

Cerithiopsis n. sp.? aff. C. halia Bartsch. Height (incomplete) 3.6 mm, width 2 mm USNM 649266. Loc. M1690. 

Lirularia lirulata conica (Carpenter). 

20. Height 4.9 mm, width 4.7 mm. USNM 649267. Loc. M1691. 

31. Height 3.8 mm, width 3.4 mm. USNM 649268. Loc. M1691. 

Pupillaria pupilla (Gould). Height 6.3 mm, width 7.6 mm. USNM 649269. Loc. M1690. 

Balcis cf. B. micans (Carpenter). H eight 5.4 mm, width 2.2 mm. USNM 649270. Loc. M1691. 

Amphissa columbiana Dall. Immature specimen. Height 8.1 mm, width 3.1 mm. USNM 649271. Loc . 

M1690. 

Odostomia cf. 0. tenuisculpta Carpenter. 

B arleeia marmorea (Carpenter) . 

25. Height 2.9 mm, width 1.5 mm. 

34. Height 2.5 mm, width 1.4 mm. 

Odostomia tacomaensis Dall and Bartsch. 

Ocenebra interfossa Carpenter. 

Height 4.4 mm, width 2.3 mm. 

USNM 649274. 

USNM 649275. 

Loc. M1691. 

Loc. M1691. 

Height 3.7 mm, width 2.2 mm. 

27. Height 14 mm, width 6.6 mm. USNM 649277. Loc. M1691. 

50. Height 19.1 mm, width 9.3 mm. USNM 649278. Loc. M1690. 

USNM 649272. Loc. M1690. 

USNM 649276. Loc. M1690. 

Epitonium indianorum (Carpenter). Height 7.4 mm, width 3.3 mm. USN M 649279. Loc. M1690. 

N assarius fossatus (Gould). 

30. Height 30 mm, width (incomplete) 15.2 mm. USNM 649280. Loc. M1691. 

48. Immature specimen. Height 11..5 mm, width 13.5 mm. USNM 649281. Loc. Ml690. 

Lacuna so/?:dula compacta (Carpenter). 

32. Height 2.5 mm, width 2.2 mm. USNM 649282. Loc. M1691. 

37. Height 2.8 mm, width 2.2 mm. USNM 649283. Loc. M1691. 

38. Height 2.7 rnm, width (incomplete) 2 mm. USNM 649284. Loc. M1691. 

33. Diaphana brunnea Dall. Height 1.6 mm, width 1.1 mm. USNM 649285. Loc. M1691. 

35, 36. Alvania n. sp.?, aff. A. iliuliukensis Bartsch. 

35. Height 1.5 mm, width 1 mm. USNM 649286. Loc. M1691. 

36. Height 1.5 mm, width 1 mm. USNM 649287. Loc. Ml691. 

39. Odostomia cf. 0. beringi Dall. Height 5.3 rnm, width 2.6 mrn. USNM 649288. Loc. Ml690. 

40. Odostomia cf. 0 . columbiana Dall and Bartsch. Height 4.8 mm, width 2.2 mm. USNM 649289. Loc. M1690 

41. Odostomia avellana Carpenter. Height 6.2 mrn, width 3.4 mm. USNM 649273. Loc . M1691. 

42. Odostomia cf. 0. stephensae Dall and Bartsch. Height 6.7 mm, width 2.5 rnm. USNM 649290. Loc. Ml690. 

43. Cerithiopsis paramoea Bartsch. Height 6.9 mm, width 2.3 mrn. USNM 649291. Loc. M1691. 

44. Oenopota? tabulata (Carpenter). Height 8.9 mm, width 4 mm. USNM 649292. Loc. M1690. 

45, 47. Lacuna porrecta exaequata Carpenter. 

45. Height 5.3 mm, width 4.1 mrn . USNM 649293. Loc. M1691. 

47. Height 4.1 mm, width 3.4 mm. USNM 649295. Loc. Ml691. 

46. Lacuna ca1·inata Gould. Height 5.7 mrn, width 4 mm. USNM 649294. Loc. Ml691. 

49. Ocenebra tenuisculpta (Carpenter). Height 11.9 mm, width (incomplete) 4.9 mm. USNM 649296. Loc. 

Ml690. 

51. Searlesia dira (Reeve). Height 39.5 mm, width 19.7 mrn. USNM 649297. Loc. Ml691. 
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6 

7 9 10 11 12 13 14 

15 16 17 18 19 20 

22 23 24 25 26 

28 29 30 

32 33 34 35 36 

42 43 44 

41 

40 

48 49 

PLEISTOCENE MOLLUSKS FROM CENTRAL CALIFORNIA 
FIGURE 

PLATE 3 

1. Clinocardium nuttalli (Conrad). Length 83 inm, height 79 mm. USNM 649298. Loc. l\11690. 

2. Platyodon cancellatus Conrad. Length (incomplete) 51 mm, height (incomplete) 31.5 mm. USNM 649299. 

Loc. l\11691. 

3. Trichotropis cancellata (Duclos) . Nonapertural view of an incomplete specimen. Width (incomplete) 18.2 mm. 

USNM 649300. Loc. l\11690. 

4. Mytilus cf. M. edulis forma glomeratus Gould. Length 7.8 mm. USNM 649301. Loc. l\11690. 

5, 12. Crepidula adunca Sowerby. Length 6.1 mm, width 3.9 mm, height 3.7 mm. USNM 649302. Loc. Ml691. 

6. Mya truncata Linne. Length (nearly complete) 34 mm, height 24 mm. USNM 649303. Loc. l\11690. 

7, 9. Lepeta concentrica (Middendorf!). 

7. Length 12.7 mm, width 10.5 mrn, height 4.7 mm. USNM 649304. Loc. l\11690. 

9. Length (nearly complete) 13.4 mm, width 4.5 rnm, height 5.7 mm. USNM 649305. Loc. Ml690. 

8, 20. Olivella cf. 0. pedroana (Conrad). 

8. Height 12.7 mm, width 6 mrn. USNM 649306. Loc. l\11690. 

20. Height 11.0 mm, width 5.5 rnm. USNM 649307. Loc. l\11690. 

10, 11. Velutina laevigata (Linne). Height 3.9 m.rn, width 4.4 mm. USNM 649308. Loc. Ml691. 

13. Mopalia cf. M . lignosa (Gould). Intermediate valve. Length 15.5 mm, width 7.3 mm. USNM 649309. Loc. 

l\11690. 

14. Mopalia ciliata Sowerby. Int ermediate valve. Length 16.1 mm, width 6.9 mrn. USNM 649310. Loc. M1691. 

15. Tresus nuttalli (Conrad). Length 86 mm, height 59 mm. USNM 649311. Loc. l\11691. 

16, 19. Macoma brota lipara Dall. Length 56 mm, height 47 mrn. USNM 649312. Loc. l\11691. Reworked from 

Pliocene strata. 

17. Olivella biplicata (Sowerby). Height 20.5 mrn, width 11.4 mm. USNM 649313. Loc. l\11691. 

18. Strongylocentrotus sp. Length 7.2 rnrn, width 1.4 mm. USNM 649314. Loc. l\11691. 

21. Tr·esus capax (Gould). Length 104 rnrn, height 83 mm. USNM 649315. Loc. l\11690. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 523-C PLATE 3 

8 

13 14 

PLEISTOCENE MOLLUSKS AND ECHINOID FROM CENTRAL CALIFORNIA 
FIGURE 1. 

2, 3. 

4. 

5. 

6, 8. 

7. 

9. 

10, 11. 

12, 13. 

14. 

15. 

16, 19. 

17. 

18. 

20. 

21. 

PLATE 4 

Penitella penita (Conrad). Length 98 mm, height 50 mm. USNM 649316. Loc. M2147. 

Petricola carditoides (Conrad). Length 25.5 mm, height 18.4 mm. USNM 649317. Loc. M1691. 

Chlamys hericia (Gould). Length 40 mm, height 48 mm. USNM 649318. Loc. M1690. 

Chlamys pugetensis (Oldroyd). Length 21.5 mm, height 27 mm. USNM 649319. Loc. M1691. 

Balanus crenatus Bruguiere. 

6. Tergum. Length 3.4 mm, width 2.1 rom. USNM 649320. Loc. M1690. 

8. Scutum. Length 3.7 mm, width 4.4 mm. USNM 649321. Loc. M1690. 

Tellina buttoni Dall. Length 25 rom, height 14.2 mm. USNM 649322. Loc. M1690. 

Siliqua aff. S. patula Dixon. Length 27 mm, height 11 mm. USNM 649323. Loc. M1690. 

Cryptomya california Conrad. 

10. Length 18.7 rom, height 11 mm. USNM 649324. Loc. M1691. 

11. Length 18.9 mm, height 13 mm. USNM 649325. Loc. M1691. 

Mysella cf. M. tumida (Carpenter). Length 2.4 rom, height 1.9 mm. USNM 649326. Loc. M1690. 

Adula cf. A. diegensis (Dall). Length 20.5 rom, height 9.8 mm. USNM 649327. Loc. M1690. 

Protothaca staminea (Conrad). Length 45 rom, height 38 mm. USNM 649328. Loc. M1691. 

Macoma expansa Carpenter. Length 34 mm, height 25.5 mm. USNM 649329. Loc. M1690. 

Ostrea sp. Internal view of an immature specimen. Length 2.9 rom, height 3.1 mm. USNM 649330. Loc. 

M1691. 

Zirjaea pilsbryi Lowe. Length (incomplete) 58 rom, height 35 mm. USNM 649331. Loc. M2147. 

Macoma inquinata (Deshayes). Length 47 rom, height 35 mm. USNM 649332. Loc. M1690. 

Protothaca staminea forma ruderata (Deshayes). Length 36.5 rom, height 29.5 rom. USNM 649333. Loc. 

M1691. 

22. Saxidomus giganteus (Deshayes). Length 80 rom, height 58 rom. USNM 649334. Loc. M1690. 

U.S. GOVERNMENT PRINTING OFFICE, 1966 Q-21Q-384 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 523-C PLATE 4 

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6 

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4 

11 12 13 

10 

16 17 

15 

19 

20 21 22 

PLEISTOCENE MOLLUSKS AND BARNACLE FROM CENTRAL CALIFORNIA