University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USGS Staff -- Published Research US Geological Survey 1967 Elephant Teeth from the Atlantic Continental Shelf Frank C. Whitmore Jr. U.S. Geological Survey K. O. Emery Woods Hole Oceanographic Institution H. B. S. Cooke Dalhousie University Donald J. P. Swift Puerto Rico Nuclear Center Follow this and additional works at: https://digitalcommons.unl.edu/usgsstaffpub Part of the Earth Sciences Commons Whitmore, Frank C. Jr.; Emery, K. O.; Cooke, H. B. S.; and Swift, Donald J. P., "Elephant Teeth from the Atlantic Continental Shelf" (1967). USGS Staff -- Published Research. 236. https://digitalcommons.unl.edu/usgsstaffpub/236 This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USGS Staff -- Published Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Science, New Series, Vol. 156, No. 3781 (Jun. 16, 1967), pp. 1477-1481 mergence ended probably about 25,000 years ago. Accordingly, the outer part of the shelf must have been exposed for about 10,000 years; the inner part, about 20,000 years. Reports The presence of the teeth of masto- dons and mammoths atop the relict sand indicates that these animals lived there during the last exposure. Evidence of the reasonableness of their presence on the shelf is the discovery of many Elephant Teeth from the Atlantic Continental Shelf hundreds or perhaps thousands of mastodon and mammoth bones through- Abstract. Teeth of mastodons and mammoths have been recovered by fisher- out the entire eastern United States men from at least 40 sites on the continental shelf as deep as 120 meters. Also and Canada (8). Moreover, students of present are submerged shorelines, peat deposits, lagoonal shells, and relict sands. large Pleistocene mammals have long Evidently elephants and other large mammals ranged this region during the known that these animals must have glacial stage of low sea level of the last 25,000 years. traveled across exposed continental shelves in order to reach islands where Occasionally newspapers report the (Fig. 2) range back to 11,000 years their remains occur: notable examples dredging by fishermen of elephant teeth ago (3, 4). are Japan, England, Mediterranean from the continental shelf. Some speci- The fact that throughout most of the islands, Java, Sumatra, and other mens have reached museums, while shelf the sands have remained relatively islands of the East Indies, and small others have been lost; probably many undisturbed is indicated by terraces islands off southern California. In all more were thrown back into the ocean marking former stillstands of sea level examples known to us the maximum or remain unreported. This compilation during the period when the shoreline present depth of the intervening strait of known finds is intended to spur the crossed the shelf. Sands atop the north- or shelf is less than 120 m. This depth reporting of other discoveries both past central part of Georges Bank and sands is significant in view of a calculation, and future. southeast of Cape Cod (southeast of based upon estimated volume of ice, The teeth are molars and premolars Boston, Fig. 2), however, have been that during the Wisconsin glaciation the from both mastodons and mammoths shaped into actively moving waves of sea level was about 123 m below the (Fig. 1). All offshore discoveries known sand. Foundation borings for radar present level (9). In each of the cited to us were on the continental shelf off towers in both areas revealed silts be- areas, molars or bones of elephants the northeastern United States and on neath the sands at 40 to 60 m below have been found on the sea floor. Off its northeastward extension as Georges sea level; a shell in one of the silts had Japan, molars of mastodon and Elephas Bank (Fig. 2) (Table 1). The average a radiocarbon age of 11,465 years (5). naumanni (Makiyama) have been depth of recovery is 36 m; the maxi- Other evidence of widespread stratifica- dredged from a depth of 80 m in the mum may be 120 m. Some uncertainty tion in the top 80 m beneath the con- strait west of Kyushu and from 90 m about position and depth of the finds tinental shelf is provided by many in the Inland Sea (10). In the English results from the fact that the scallop continuous seismic profiles (6) showing Channel, especially from Dogger Bank or clam trawls may be dragged several the common presence of four or five at 30 to 40 m, bones of many Pleisto- kilometers along the bottom before reflecting horizons, each of which is cene mammals, including mammoths, being hauled. probably a sediment surface produced have long been reported by fishermen Most of the continental shelf is during a low sea level associated with (11). Off southern California about floored by detrital sand that is iron a glacial stage of the Pleistocene epoch. 1950, R. S. Dietz recovered an upper stained and generally coarser grained Thus the present surface of the con- second and an upper third molar of than sediments closer to the present tinental shelf is not older than the Archidiskodon imperator Leidy at a shore (1). For these reasons the sand is Wisconsin glaciation, and much of it depth of 5 m near Huntington Beach, considered relict from times of glacially has received little subsequent sedi- and other finds of bones and molars lowered sea level. Present on or just ment. from near Santa Barbara have been below the surface of the sand at water The evidence indicates that the pres- reported since 1960 by oil company depths as great as 90 m are shells of ent continental shelf was a broad divers. oysters, Crassostrea virginica (Gmelin), coastal plain about 15,000 years ago, The distribution pattern of elephant that lived in depths shallower than and that it gradually submerged as teeth on the sea floor off the Atlantic about 6 m. Supporting evidence of water from glacial ice returned to the coast (Fig. 2) shows three concentra- former shallow water is provided by ocean. The sea-level rise curve derived tions: Georges Bank, off New York exposures of intertidal salt-marsh peat from the present water depths of the City, and off the mouth of Chesapeake that is now as deep as 59 m. Fresh- dated shells and peat differs only Bay. These parts of the continental shelf water peats also are present. Compari- slightly from that of Shepard (7), which are the most intensively exploited for son of samples of peat taken from the is based upon data from many places scallops, clams, and bottom fishes, all sea floor (eight) and from ponds ashore in the world. The region had been sub- of which require the dragging of heavy shows that the pollen assemblages are merged during several earlier inter- trawls along the bottom. Thus the dis- the same throughout (2). Radiocarbon glaciations; although the dates are tribution pattern merely reflects the dates for these oyster shells and peats poorly known, the next previous sub- intensity of effort or the degree of op- 16 JUNE 1967 1477 are portunity for finds, as well as the extent that apparently preferred by Mammu- Most fossil elephant specimens to which specimens are rescued and thus primigenius (Blumenbach) in isolated teeth. Tooth patterns are gen- passed to scientific institutions. It is Siberia and Alaska (12). erically and, to some extent, specifically notable that specimens at our disposal Occurrence of a suitable diet does characteristic, and certain features of came from relatively few ships' cap- not, however, prove that the mammoth mammoth molars may have ecologic sig- tains. teeth found on the continental shelf nificance. Very generally, the distribu- Occurrence of the teeth as far as represent the woolly mammoth. The 11 tion of types of mammoth teeth in the 300 km from the present shore and mammoth teeth available from the area periglacial land areas of the late- their wide distribution show that the between 42?08' and 36?46'N (Fig. 2) Pleistocene epoch of North America proboscideans lived on the shelf. One (Table 1) are somewhat different from indicates the presence of animals hav- may assume, therefore, that this region isolated molars of several species of ing fairly hypsodont teeth with many was well covered with land vegetation. Mammuthus obtained on land. We tooth plates. Such teeth typify Mam- Evidence of such vegetation is pro- should also point out that most of the muthus primigenius (Blumenbach), the vided by the finding of twigs, seeds, specimens recovered come from the woolly mammoth, that probably ate and pollens of spruce, pine, and fir wide-ranging mastodon Mammut ameri- tundra grasses and the foliage of within peat deposits that are now deeply canum (Kerr), although this domi- conifers. submerged; freshwater diatoms also are nance in the collections may well reflect Generally south of the range of found (4). The age of this material is the greater inherent strength of masto- M. primigenius on land was M. columbi 11,000 years (4), and the assemblage don molars than of the fissile plated (Falconer), the Columbian mammoth. indicates a boreal climate similar to molars of the mammoth. The ranges of the two species, and of Table 1. Proboscidean teeth dredged from the sea floor off the Atlantic coast of North America. Depths in parentheses are taken from charts. Abbreviations: R, right; L, left; M2 second upper molar; M, third lower molar; AMNH, American Museum of Natural History; ANSP, Acad- emy of Natural Sciences, Philadelphia, Pa.; CB, collection of C.