North Atlantic Ice-Rafting: A Major Change at 75,000 Years Before the Present

Science  10 Jun 1977:
Vol. 196, Issue 4295, pp. 1208-1211
DOI: 10.1126/science.196.4295.1208


During the last interglacial-to-glacial climatic cycle [127,000 to 10,000 years before the present (B.P.)], the fundamental geographic shift in the main axis of ice-rafting deposition occurred at 75,000 years B.P. An earlier meridional depositional maximum along the Greenland-Newfoundland coasts was superseded by a nearly zonal and much stronger axis some 1500 kilometers to the south along 40°N to 50°N. Both depositional patterns are best explained by cyclonic flow in the subpolor gyre, with the depositional shift related to the retreat of warm, ice-melting North Atlantic drift water from the northwestern half of the gyre. Similar shifts must have characterized preceding interglacial-glacial cycles.