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The stratigraphy of Tjörnes, Northern Iceland, and the history of the Bering Land Bridge
Einarsson, T.; Hopkins, D.M.; Doell, R. (1967). The stratigraphy of Tjörnes, Northern Iceland, and the history of the Bering Land Bridge, in: Hopkins, D.M. (Ed.) The Bering Land Bridge. pp. 312-325
In: Hopkins, D.M. (Ed.) (1967). The Bering Land Bridge. Stanford University Press: Stanford. ISBN 0-8047-0272-1. ix, 495 pp., more
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Keyword
    Marine/Coastal
Authors  Top 
  • Einarsson, T.
  • Hopkins, D.M.
  • Doell, R.
Abstract
    Bering Strait opened in its present form during late Pliocene or early Pleistocene time, allowing a flood of mollusks of Pacific boreal ancestry to reach lceland more than three million years ago. The Arctic Ocean was still relatively warm and probably ice-free; the migrations took place at least half a million and perhaps more than a million years before the first widespread Pleistocene glaciation in lceland. The first glaciation on Tjörnes took place at least 1.9 and perhaps between 2.4 and 3.0 million years ago; it was followed by at least nine later glaciations separated by lengthy nonglacial intervals. This record is probably unique only in its completeness. A reconstruction of the former topography indicates that the local relief on Tjörnes was even less conducive to local glaciation during most of Pleistocene time than it is at present; the tillite beds on Tjörnes evidently were deposited by large ice sheets originating in central lceland. The ten glacial cycles recorded on Tjörnes probably represent a minimum estimate of the total number of important worldwide Pleistocene cold fluctuations and glacial cycles. This conclusion implies that Pleistocene climatic history is much more complex than is suggested by the classical concepts evolved for the Alps and for the mid-continent of North America, which involve only four or five glaciations, and it casts serious doubts on intercontinental correlations of the older Quaternary glacial deposits. lt also implies that the Bering Land Bridge may have been renewed as many as ten times by glacio-eustatically lowered sea level during the Pleistocene Epoch.
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