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Paleo Slide Set: Heinrich Events: Marine Record of Abrupt Climate Changes in the Late Pleistocene
Data from several sediment cores from Dowdeswell et al. [1995].
When coupled with the previous map of source areas documented by Bond et al (1992), this slide strongly suggests that the major cause of Heinrich events was fluctuations in the Hudson Strait ice stream, which drained a large fraction of the former Laurentide Ice Sheet.

Heinrich events have several distinctive properties that allow them to be distinguished over large distances. The thickness of H-1 and H-2 events (radiocarbon dated at 14.5 kyr and 20.5 kyr, respectively) in each core were measured. Next, these thicknesses were plotted on a map. Finally, lines of equal thickness were drawn through the map, much as the isotherms (lines of equal temperature) and isobars (lines of equal pressure) on a meteorological map. The thickest sediments were found to lie off the southern coast of Baffin Island, right where the Hudson ice stream flowed into the ocean. To the south and northeast of this area as documented by Bond et al (1992), the detrital carbonate sediments became thin or even absent, suggesting that the carbonate rich layers were restricted to areas of high IRD counts that amassed during the last glaciation.

Photo Credits:
John T. Andrews, Thomas G. Andrews
NOAA Paleoclimatology Program and INSTAAR, University of Colorado, Boulder

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Last Modified: 12 October 2001

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