JOHN M. ZEIGLER Woods Hole Oceanographic Institution, Woods Hole, Mass. SHERWOOD D. TUTTLE State University of Iowa, Iowa City, Iowa HERMAN J. TASHA Woods Hole Oceanographic Institution, Woods Hole, Mass. GRAHAM S. GIESE Graduate School of Oceanography, University of Rhode Island, Kingston, R. I.

Pleistocene Geology of

Outer ,

Abstract: Glacial deposits of Outer Cape Cod clay was 20,700 ± 2000 years old, for those are mainly of stratified drift occurring in three collected below the silt-clay, 26,900 ± 700 years units: sand and gravel at the top, a silt-clay layer in old. It is proposed that the glacial material of the middle, and more sand and gravel at the bot- Outer Cape Cod is entirely Wisconsin in age and tom. These deposits contain shells and other that the silt-clay sediments represent a slight period marine materials picked up by the glacial ice as of warming. All the stratified drift was presumably it moved across the Gulf of and Cape Cod deposited subaerially or in temporary shallow pools Bay. A C14 date for shells collected above the silt- formed on the local drift surface.

CONTENTS Introduction 705 Figure Acknowledgments 705 1. Map of Cape Cod area, Massachusetts .... 706 Pre- bedrock 706 2 . Map of Cape Cod and submerged banks on the Types of glacial deposits 708 Continental Shelf 707 General statement 708 3. Geologic sections of material exposed in the cliffs 710 Glacial till 709 4. Schematic block diagram of the area in the Sands and gravels 709 vicinity of Wellfleet looking north, showing Silt-clay beds 709 the suggested conditions of deposition during Age of glacial deposits 710 accumulation of the glaciofluvial deposits . 711 Conditions of deposition 712 Summary 713 Plate Facing References cited 713 1. Glacial sediments in cliffs near Cape Cod Light, Massachusetts 708

quired a study of the glacial deposits which INTRODUCTION make up the core of the Cape. We will attempt Cape Cod, a low peninsula of gravel, sand, to assign the deposits to glacial stage and sub- and clay, extends from southeastern Mas- stage, determine the absolute dates of their sachusetts into the Gulf of Maine (Fig. 1). deposition, and suggest mechanisms and en- Outer Cape Cod, the forearm, wrist, and hand vironments for their accumulation. of the Cape, is made of glacial deposits and of postglacial wave-built features. Long, straight ACKNOWLEDGMENTS beaches encircle most of the Outer Cape; in The studies on Cape Cod were partially some places the beaches lie in front of high supported by the Geography Branch of the crumbly cliffs. Office of Naval Research under contract Nonr- For the past 25 years or more scientists from 1254(00) NR-388-018 and partially by the the Woods Hole Oceanographic Institution Geophysics Branch under contract Nonr- have been studying the beaches of Outer 2196(00) NR 083-004. We are indebted to Cape Cod (Schalk, 1938; Miller and Zeigler, Dr. Francis P. Shepard and his associates at 1958; Zeigler and others, 1959; 1960; 1961). Scripps Institution of Oceanography, Cali- Their questions regarding origins of the fornia, for a C14 date of material from the Provincelands at the end of Cape Cod, re- glacial drift. Very important opinions on the

Geological Society of America Bulletin, v. 75, p. 705-714, 4 figs., 1 pi., August 1964 705

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age of pollen from our wells were kindly given geophysical exploration indicate that the by Dr. Elso Barghoorn of Harvard University, glacial deposits of Outer Cape Cod rest on Dr. Johan Groot of the University of Delaware, Cretaceous and Tertiary rocks forming a and Dr. Eugene J. Tynan of the University of northward extension of the Atlantic Coastal Rhode Island. The town officials of Province- Plain and on units of the crystalline basement town, Truro, Wellfleet, Eastham, and Orleans of New England which are probably . co-operated in permitting us access to town Since there are relatively few data from this property and beaches. large area, our geologic knowledge is somewhat limited. PRE-PLEISTOCENE BEDROCK Paleozoic crystalline rocks are exposed along All available information from scattered out- the western edge of Massachusetts Bay as far crops and data derived from drilling and south as Duxbury, and appear again along the

42° 2 5'

STELLWiGEN BANK

PROVtNCELANDS HOOK I CAPE COD LIGHT 42°00'

I

41°30

NAUTICAL MILES SHOALS 0 5 10 15 I

41°00' 70° 55' 70° 30' 70°00' 69°30 Figure 1. Map of Cape Cod area, Massachusetts

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western shore of Buzzards Bay (Emerson, coquina, in which Crosby (1879) recognized 1917). Koteffand Gotten (1962) described the and dated as Eocene 25 species of molluscan materials found in two deep wells drilled at bivalves, have been found in the glacial mat- Harwich (Fig. 1). These holes penetrated 435 erial of Outer Cape Cod. Because the boulders feet of Pleistocene materials to sericitized were rounded and smoothed, he inferred that micaceous phyllitic schist. Zeigler, while diving they were eroded from Eocene beds somewhere in the Gulf of Maine in 1954, collected rocks north of Cape Cod (cf. Woodworth and from a submarine outcrop at Cashes Ledge Wigglesworth, 1934, p. 248). Stetson (reported (Fig. 2). L. D. Toulmin (1957) identified these in Cushman, 1936) dredged fragments of fragments as Quincy . rock identified as Cretaceous and Tertiary from

Figure 2. Map of Cape Cod and submerged banks on the Continental Shelf. The submarine plateaus which underlie Cape Cod, the adjoining islands, and the banks are underlain by Cretaceous and Tertiary beds.

Cretaceous and Tertiary sands and clays are the walls of several submarine canyons south- exposed at Gay Head on Martha's Vineyard east of Cape Cod along the edge of the Conti- and in the cliffs facing Vineyard Sound. A nental Shelf. Woods Hole Oceanographic In- small patch of Cretaceous and possibly Miocene stitution personnel have reported sediments sediments is exposed on the southeastern edge which contain much Eocene pollen from four of Nonamesset Island in the wells in the shallow subsurface of Outer Cape (Woodworth and Wigglesworth, 1934, p. 248). Cod (Zeigler and others, 1960). These same No rocks older than glacial deposits are known sediments yielded carbonized wood which from the island of Nantucket. Emerson (1917) proved to be older than 42,000 years (C14 reported the identification of possible subsur- analysis made by Scripps Institution of Ocean- face Miocene material resting on granite near ography). The sediments from the deeper Duxbury. Fishermen occasionally dredge up parts of these wells seem to be better sorted slabs of probable Cretaceous and Tertiary rocks than and are distinctly different from the over- on the northeast part of Georges Bank (Verrill, lying younger sands. Nothing has proved con- 1878). Boulders of fossiliferous limestone and clusively that the pollen is not reworked in the

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/75/8/705/3432107/i0016-7606-75-8-705.pdf by guest on 29 September 2021 Figure 1. View from the beach up across beds of sand and gravel. The silt-clay unit is nearly covered about }/% of the way up the slope. Height of the cliff here is about 150 feet

Figure 2. Contorted beds in the silt-clay unit exposed following a storm. Photo taken Jan. 1, 1954 by Henry C. Stetson. Width about 10 feet

GLACIAL SEDIMENTS IN CLIFFS NEAR CAPE COD LIGHT, MASSACHUSETTS ZEIGLER AND OTHERS, PLATE 1 Geological Society of America Bulletin, volume 75

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South Channel leaving the intervening ridge glauconite. The ice also must have been filled between the lobes uncovered until it was finally with material picked up from the igneous and overwhelmed. During deglaciation this ob- metamorphic terrain to the north before it struction would have caused splitting and reached the sea. Therefore, one would expect melting, and the interlobate area would always the drift to be a mixture of marine and crystal- have opened up in the same place. line material. North of the morainal topography in East- The glacial deposits of Outer Cape Cod can ham is a series of gently sloping plains under- be divided roughly into three units: glacial lain by sand and gravel, the Eastham, Well- till, sands and gravels, and silt-clay beds. The fleet, and Truro plains of Grabau (1897) and last two make up the stratified drift that under- Woodworth and Wigglesworth (1934, p. 271- lies most of Outer Cape Cod. 277). The surfaces of these plains, superficially smooth with a gentle southwestward slope, are Glacial Till trenched by steep-sided flat-floored, southwest- An area of unmistakable glacial till is exposed ward-sloping misfit and dry valleys and pitted in the town of Eastham near the location of with numerous ice block holes. The plains the former Nauset Coast Guard Station, now terminate against the sea as cliffs in which one the Cape Cod National Seashore Headquarters. can see a vertical section of the sediments Grabau (1897) and Woodworth and Wiggles- (PI. 1). The height of the cliffs ranges laterally worth (1934) include this section within the from 20 to 177 feet (See U. S. Geol. Survey Sandwich , an area of knobby morainal Wellfleet topographic map 1/24000, 1944). topography extending eastward to the ocean. All the deposits are difficult to observe in the The material is exposed in the cliffs that field for several reasons. The sandy materials, separate the beach from the parking lot and after the ground has thawed, tend to dry out also a few hundred yards north of the parking and form a blanket of loose material which lot. The till is dark brown, relatively tough, commonly covers the entire cliff face until and contains many stones and some clay. storms remove it from the base. Since big Characteristically the till has no bedding and storms occur irregularly, 2 years or more may is unsorted. In June 1962, we found, exposed in pass before the cover is removed. The entire the cliffs 1000 feet north of Cape Cod Light, cliff section in a given locality is rarely exposed, two small patches of till a few hundred feet and the storms that remove the slumped long. Since the cliffs retreat approximately 3 material also erode the beds, making it impos- feet per year, these exposures will soon be sible to revisit the same exposure and examine destroyed, and others may be uncovered. its special features. The best time to look at the cliff material is in late winter, after a northeast Sands and Gravels storm. However, wind and cold make field The deposits north of the till at Nauset can work uncomfortable at that time of the year. be grouped stratigraphically into three units: Sediment size, sorting, and lithology vary sands and gravels at the top, a sometimes dis- greatly, often within 100 feet. This is most continuous silt-clay zone in the middle, and visible in the silt-clay beds, which can change more sands and gravels at the base (Fig. 3). from dense sticky clay to white powdery silt in This division is exposed at many places in the a few feet, making it very difficult to identify cliffs facing the sea (Plate 1, fig. 1), and is the unit from place to place. From a distance encountered in wells widely spaced over Cape the cliffs seem to be tan, but a handful of Cod as well as in glacial deposits to the west sand may be either white or tan. The tan color of (Hyyppa, 1955). comes from oxidized zones, mostly in the pebbly layers. Silt-Clay Beds Examining gravel layers in more detail, one In contrast to the sands and gravels above discovers a wide variety of materials: cobbles of and below them, the silt-clay beds contain very igneous and metamorphic rocks; occasional little coarse material. In some places the fossiliferous cobbles; carbonized wood frag- material is evenly bedded dark clay, virtually ments; pieces of marine shells. Even a cursory free of silt; in others, it is composed of lami- examination of the mineral grains shows that nated silts and clays, in still other areas, the glauconite is a common dark mineral. The unit is marked by thick or thin beds of almost glacial ice, moving across what is now Cape pure silt. The contacts of the silt-clay beds Cod Bay, could have picked up both shells and with the underlying and overlying beds are as

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unpredictable as the lithology. We have worth and Wigglesworth, 1934;Hyyppa, 1955). observed the silt-clay unit to lie unconformably Sayles and Knox (1943) thought it was a clay over cobble and gravel channel fills; elsewhere till; Hyyppa decided on the basis of diatoms it is perfectly conformable; still elsewhere, the that the clay was marine. The diverse opinions contacts are gradational. Both the top and held by skilled workers is ample proof that bottom of the silt-clay unit are apt to be working with the unit is difficult. Since the marked by a hard iron-cemented zone which type Gardiner's Clay is recognized as marine might be less than 1 inch or more than 1 foot on the basis of megafossils and generally ac- thick. These iron-cemented zones occur oc- cepted as interglacial in age, we believe it casionally within the unit. In some places the inappropriate to use the term Gardiner's Clay silt-clay beds are deformed—thickened and for the silt-clay deposits of Outer Cape Cod.

W 80 DUNE SAND AND SOIL 1500 FEET N. OF CAPE COD LIGHT 70 UPPER SANDS AND GRAVELS

50

SILT - CLAY

30 -

LOWER SANDS AND GRAVELS 20 DUNE SAND AND SOIL

UPPER SAND AND GRAVEL 10 20,700 YRS< SILT-CLAY BEACH

250 FEET S. OF THE HEAD OF PAMET R. Figure 3. Geologic sections of material exposed in the cliffs. (No vertical exaggeration)

rolled into folds—and occasionally faulted. Figure 2 of Plate 1, taken following a winter AGE OF GLACIAL DEPOSITS storm, shows these beds. Woodworth and Wig- Fortunately, the sand and gravel deposits glesworth (1934, p. 256) mapped a syncline in both above and below the silt clay contain the clays in the cliffs north of Cape Cod Light. shell material bedded with the sands. Shells It is unlikely that these structures were formed from two places have been dated on the basis of by ice push or ice drag since we do not believe their C14 content. One shell collection was that glacial ice to any great extent was present taken below the silt-clay unit and another over Cape Cod either when the beds were above it. Shells collected 8 feet below the base deposited or later. We suggest that these of the silt-clay 1000 feet north of Cape Cod features were produced by slump or lateral Light were dated 26,900 + 700 y.b.p. and sliding in downslope directions towards Great identified by Dr. Horace Richards, University South Channel and Cape Cod Bay while or of Pennsylvania, as Mesodesma deaurata after the ice was melting. (Turton). Shells collected 30 feet above the The silt-clay unit has attracted much at- top of the silt-clay 300 feet south of the north- tention. It has been called Gardiner's Clay by east outlet of the Pamet River Valley were several authors (Fuller, 1906; 1914; Wood- dated 20,700 + 2000 y.b.p. and identified by

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Dr. Robert Hessler as Mesodesma arctatum Flint's (1953) assignment of the Martha's (Fig. 4). Both analyses were made by Isotopes Vineyard-Nantucket and the Buzzards Bay- Incorporated. Sandwich to the lowan-Tazewell In accepting the isotope dates for the shell substages, and the glacial drift near Boston fragments we have considered the possibility to the Gary, still seems reasonable. The sands that they may have been altered. The glacial and gravels are younger than the shells in drifts of Outer Cape Cod are very porous and them. Assuming that they are somewhat it is certainly possible that ground water has younger than the Buzzards Bay-Sandwich flowed over the shells and has exchanged some moraines which lie a few miles to the south, and portion of the carbonate. The shell surfaces older than the Gary drift in the Boston area, however, are in good condition but show slight the absolute age of the sands and gravels must evidence of solution. lie between 19,500 y.b.p. (approximate C14 date for the Tazewell of Illinois) and 15,500 y.b.p. (approximate C14 date for the Gary of Illinois) (Frye and Willman, 1960) and there- fore the shells in the upper sands and gravels are not more than 2000 or 3000 years older than the drift. The till exposed at Nauset, part of the inner belt of moraines, which appears fresh and un- weathered: it underlies the dated stratified drift and is certainly Wisconsin. The C14 dates from the shells indicate that the fluvioglacial deposits are clearly Wisconsin, as is the silt-clay layer. The age thus deter- Figure 4. Schematic block diagram of the mined is reasonable in terms of the evidence area in the vicinity of Wellfleet looking normally used in dating Pleistocene deposits. north, showing the suggested conditions of deposition during accumulation of the The topography of the Outer Cape is fresh glaciofluvial deposits. These materials and undissected. Ice block holes seem as new were left by streams of greatly varying as if formed recently. These holes in the upper volumes and velocities as floodplain de- sands and gravels lead us to believe that the posits, as fan deposits, as lake beds in present land surface is no older than Tazewell. temporary lakes, and as combinations of Comparing these dates with absolute dates these methods. given by Frye and Willman (1960) for the classical Wisconsin of Illinois, they are Farm- Much carbonized wood can be found in the dalian and early Woodfordian (Farmdale, glacial sediments, but three samples were all lowan, and Tazewell stages of the former too old (age greater than 45,000 years) to date classification: Leighton, 1960). Frye and Will- by C14 methods. The age of the shells sub- man suggest a warming period between early stantiates our belief that the carbonized wood Wisconsin deposits (30,000-35,000 y.b.p.) and is very likely reworked from older sediments. the deposition of the Shelbyville moraines The Cretaceous and Tertiary sediments ex- (19,200 + 700) at the base of the classical posed on Martha's Vineyard contain many Wisconsin of Illinois (Tazewell). An inter- carbon fragments. Material recovered from stadial between 24,600 and 28,200 has been wells drilled into the Tertiary sediments under- dated by deVries and Dreimanis (1960). lying the Provincetown Hook (Zeigler and These dates have great significance for inter- others, 1960) also contained carbon fragments. preting the geology of the Cape Cod region. Such Cretaceous and Tertiary beds underlying Past investigators have had very little with Cape Cod Bay undoubtedly were eroded by which to work. Upham (1879) made an early advancing ice and were sources of the carbon attempt to establish age relationships within fragments found in the drift. Thus the glacio- the glacial sequence. He believed he could fluvial deposits are somewhat younger than the trace the Harbor Hill and Ronkonkoma shells they contain. These shells presumably moraines on across the Appalachians were picked up a few miles to the north by into the Mississippi valley to an area of accepted glacial ice crossing the Gulf of Maine, carried Wisconsin deposits. He then traced the mo- along and deposited with all the other detritus. raines in the opposite direction beneath the

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sea to Rhode Island and Martha's Vineyard, However, being located almost at the extreme and finally to Cape Cod where the moraines edge of the glaciated areas, Cape Cod may not on the eastern side of Buzzards Bay are called have been greatly affected by ice loading. It the Falmouth moraines, those on the north has also been suggested that the land levels shore of Cape Cod the Sandwich moraines. may rise somewhat around the margins of Later investigators such as Woodworth and glaciated areas in response to the lowering of Wigglesworth (1934) and Mather and others the land under the weight of the ice. Redfield (1942) accepted the Wisconsin age and elabo- and Rubin (1962) presented a sea-level curve rated on the details of topography and strati- for Cape Cod which clearly shows a rising sea graphy. Woodworth and Wigglesworth went level over approximately the last 4000 years, so far as to describe material from Cape Cod part of all of which might be due to none- and the neighboring islands which they as- ustatic submergence. signed to every glacial and interglacial epoch The sands and gravels and the silt-clay beds, from the Nebraskan to the Wisconsin. They because of their irregular bedding, variation in dated the "Gardiner's Clay" as Yarmouth lithology, size, and sorting, indicate a water- interglacial. Sayles and Knox (1943) inferred laid deposit. Yet the discontinuity of the bed- five ice advances for the Cape Cod area and ding and abrupt changes in lithology indicate suggested that the upper till was of late nonuniform conditions of deposition. Wilson Wisconsin age. Hyyppa (1955) dated the silt- (1906) proposed a large moraine and ice- clay as definitely Wisconsin and suggested that dammed lake, covering most of Cape Cod and it belongs to the lowan-Tazewell interstadial. Cape Cod Bay, in which the sands and gravels of the Truro, Wellfleet, and Eastham plains CONDITIONS OF DEPOSITION were deposited. The water levels served as The sands, gravels, isolated till patches, and temporary base levels for the outwash plains. occasional boulders are deposits one would Instead of a single extensive lake or swamp expect in a depression between active ice there might have been several lakes or back- lobes; these are high-energy deposits. The swamp areas, many of them intermittent. The silts and clays, however, represent a time of floors of these lakes might have formed a sur- lower energy in the meltwater streams, and an face of very low relief over which no organized accumulation of fines washed out and sorted stream of water flowed with any considerable from the heterogeneous material brought there velocity. With ice lobes to the east and west by the glacial ice. Such materials might have the interlobate area might have alternated accumulated in the sea, in a temporary lake, or between flooding due to damming and al- subaerially on an alluviating surface (Fig. 4). luviating surfaces made by shifting rivers. The Hyyppa (1955) states that the diatom flora finer sediments, deposited during times of low from the silt-clay is composed of 98-100 per velocity streams and damming, would contain cent marine species. Furthermore, he correlates diatoms, pollen, spores, and any other fine silt-clay zones on Cape Cod with outcrops on materials that could be washed out of the drift. Martha's Vineyard, along the west side of Cape The larger shell fragments could be moved Cod Bay, and inland as far as Bridgewater and only when meltwater streams were capable of Taunton Massachusetts. He therefore believes moving coarser sediments and therefore would that the silt-clay is a marine deposit laid down not be present in the silt-clay beds. Neither in a fairly large sea during the lowan-Tazewell macroshells, whole or fragmented, nor fora- interstadial. minifera have been found in the silt-clays. This Information about sea-level changes does not is negative information, but if these deposits invalidate this theory because Curray (1961) were laid down in the open sea one would showed a high stand of sea level 29,000 y.b.p. expect to find at least a few shell fragments or only 25 feet lower than the present sea level; foraminifera. The iron-cemented zones in the however, if one chooses to use this evidence one drift might well be bog iron deposits. Bog must also use tectonics to get the present level iron is forming today in such ice block holes as of the silt-clay beds to the lower elevation re- Duck Pond in Wellfleet and near Roaring quired for submarine deposition. Tectonic Creek on Martha's Vineyard. changes during the Early Wisconsin are difficult In view of the inconsistent evidence cited to identify in the Cape Cod area. Theoretically, we think that a subaerial rather than marine during ice advances sea level is lowered origin for the gravels, sands, and silt-clay is in- eustatically and the level of the land is lowered dicated. Presumably then all the enclosed or- isostatically; both rise during times of retreat. ganic material—carbon fragments, shell frag-

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ments, and microfossils—had been eroded and Cape Cod are glaciofluvial in origin, and were transported by the ice to accumulate as part of deposited by meltwater streams flowing be- an interlobate deposit of glacial outwash. Be- tween two large ice lobes. Carbon fragments cause it is obvious that the carbon fragments from the glacial drift are older than 42,000 and the fossiliferous boulders are transported, years whereas shell fragments are between probably the rest of the organic material has 20,000 and 30,000 years old. Sea water levels been transported also. If some of the sediments were probably too low during those times for are truly marine, according to the age deter- the glaciofluvial deposits to be marine. Since minations, unrecognizable changes in elevation the carbon fragments are transported, the must have occurred. shells and other marine organisms are probably transported also. An early Wisconsin age, based SUMMARY on the C14 dates> agrees with the appearance of Sedimentary characteristics show that the the drift topography, still pitted and uneroded. main deposits of the central part of Outer

REFERENCES CITED Crosby, W. O., 1879, On the occurrence of fossiliferous boulders in the drift of Truro on Cape Cod, Massachusetts: Boston Soc. Nat. History Proc., v. 20, p. 136-140 Curray, Joseph R., 1961, Late sea level: A discussion: Geol. Soc. America Bull., v. 72, p. 1707-1712 Cushman, Joseph A., 1936, Geology and paleontology of the Georges Banks Canyons. Part IV. Cretace- ous and late Tertiary Foraminifera: Geol. Soc. America Bull., v. 47, p. 413-440 Drake, C. L., Ewing, Maurice, and Sutton, G. H., 1959, Continental margins and geosynclines: the east coast of North America north of Cape Hatteras, p. 110-198 in Physics and chemistry of the earth, v. 3: London, Pergamon Press, 464 p. Emerson, B. K., 1917, Geology of Massachusetts and Rhode Island: U. S. Geol. Survey Bull. 597, 289 p. Flint, Richard F., 1953, Probable Wisconsin substages and late Wisconsin events in northeastern United States and southeastern Canada: Geol. Soc. America Bull., v. 64, p. 897-920 Frye, John C., and Willman, H. B., 1960, Classification of the Wisconsin stage in the Lake Michigan glacial lobe: 111. Geol. Survey, Cir. 285, 24 p. Fuller, Myron L., 1906, Clays of Cape Cod, Massachusetts: U. S. Geol. Survey Bull. 285, p. 432-441 1914, Geology of Long Island: U. S. Geol. Survey Prof. Paper 82, 231 p. Grabau, A. W., 1897, The sand plains of Truro, Wellfleet and Eastham, Massachusetts (Abstract): Science, new ser., v. 5, p. 334-335 Groot, Catharine R., and Groot, Johan J., 1964, The pollen flora of Quaternary sediments beneath Nantucket Shoals: Am. Jour. Sci., v. 262, p. 488-493 Hoskins, Hartley, and Knott, S. T., 1961, Geophysical investigation of Cape Cod Bay, Massachusetts, using the continuous seismic profiler: Jour. Geology, v. 69, p. 330-340 Hyyppa, Esa, 1955, On the Pleistocene geology of southern New England: Bull, de la Commission Geolog- ique de Finland, no. 167, p. 156-225 Jahns, Richard H., and Willard, Max E., 1942, Late Pleistocene and Recent deposits in the Valley, Massachusetts: Am. Jour. Sci., v. 240, p. 161-191, 265-287 Koteff, C., and Gotten, J. E., 1962, Preliminary results of recent deep drilling on Cape Cod, Massachusetts: Science, v. 137, no. 3523, p. 34 Leighton, Morris M., 1960, The classification of the Wisconsin glacial stage of north central United States: Jour. Geology, v. 68, p. 529-552 Mather, Kirtley F., Goldthwait, Richard P., and Thiesmeyer, Lincoln R., 1942, Pleistocene geology of western Cape Cod, Massachusetts: Geol. Soc. America Bull., v. 53, p. 1127-1174 Miller, Robert L., and Zeigler, John M., 1958, A model relating dynamics and sediment pattern in equilibrium in the region of shoaling waves, breaker cone, the foreshore: Jour. Geology, v. 66, p. 417-441 Redfield, Alfred C., and Rubin, Meyer, 1962, The age of salt marsh peat and its relation to recent changes in sea level at Barnstable, Massachusetts: Nat. Acad. Sci. Proc., v. 48, p. 1728-1735 Sayles, Robert W., and Knox, Arthur S., 1943, Fossiliferous tills and intertill beds of Cape Cod, Mass- achusetts: Geol. Soc. America Bull., v. 54, p. 1569-1612

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MANUSCRIPT RECEIVED BY THE SOCIETY SEPTEMBER 9, 1963 CONTRIBUTION No. 1420, WOODS HOLE OCEANOGRAPHIC INSTITUTION, WOODS HOLE, MASS.

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