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Paleo Slide Set: The Ice Ages
A 10m-piston core being raised to the deck of the Hudson.
Milankovitch's theory would be resurrected once again, however, this time from the depths of the world's oceans. Beginning in the 1960s and continuing to the present day, scientists have found overwhelming support for the Milankovitch theory in long cores such as this one extracted from the ocean floor. These oceanographic studies have two major advantages over the studies of terrestrial glacial deposits done in the 1950s that seemed to refute the Milankovitch theory. First of all, ocean cores provide a much more continuous record of glaciation than terrestrial deposits do. The reason for this being that subsequent waves of glaciation often erased or altered traces of earlier glacial and interglacial periods. Secondly, by the late 1960s, sediment cores pulled from the oceans could be dated with relative confidence as far back as 650,000 yr. BP. In contrast, radiocarbon dating becomes much less accurate on materials over 40,000 yr. old. Thus, the initial land-based studies that claimed to provide chronologies for glaciation over the past 80,000 years relied heavily on some very tenuous dates.

Photo Credits:
Anne Jennings
INSTAAR, University of Colorado, Boulder
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Last Modified: 12 October 2001

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