Amy D. Fox

University of New Hampshire

Geology


1993

Mentor: Dr. Francis S. Birch, Professor of Earth Sciences

Pleistocene-Holocene History of the New Hampshire Inner Continental Shelf Based on Benthic Foraminiferal Assemblages

Sediments from an 8 3 meter long vibracore taken off the coast of New Hampshire at a depth of approximately 60 meters contain two distinct benthic foraminiferal assemblages indicating a significant change in oceanic conditions after 13,170 radiocarbon years before present (yr BP). The first assemblage, characterized by abundant Elphidium excavatum (Terquem) and Cassidulina islandica Norvang and located in the bottom 5 to 6 meters of the core, is interpreted to indicate the presence of a subarctic environment in the area during the end of the retreat of the Laurentide ice sheet from southern New Hampshire between roughly 13,500 and 13,000 yr BP. Within the top 2 meters of the core is the second assemblage, which is composed almost entirely of very sparse specimens of the arenaceous form Proteonina atlantica Cushman, indicating more temperate and restricted conditions similar to those that exist in parts of the New England coast today. The existence of this faunal break representing the change from late-glacial to postglacial conditions on the New Hampshire inner continental shelf may be correlated with a similar ecostratigraphic horizon observed in sediments from the continental shelves of Eastern Canada and Scandinavia.

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