Large millennial-scale fluctuations of the southern margin of the North American Laurentide Ice Sheet occurred during the last deglaciation, when the margin was located between about 43 degrees and 49 degrees N. Fluctuations of the ice margin triggered episodic increases in the flux of freshwater to the North Atlantic by rerouting continental runoff from the Mississippi River drainage to the Hudson or St. Lawrence Rivers. We found that periods of increased freshwater flow to the North Atlantic occurred at the same time as reductions in the formation of North Atlantic Deep Water, thus providing a mechanism for observed climate variability that may be generally characteristic of times of intermediate global ice volume.

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Easter Island occupies an exceptionally isolated position in the south Pacific Ocean. It is entirely volcanic, and is famous for its giant statues. Late Quaternary sediments have been investigated in three craters: Ran0 Raraku, Ran0 Aroi and Ran0 Kao, giving a continuous record over the past 30 Ka. Pollen records indicate that the island was formerly forested. Palynological and sedimentological evidence suggests a Late Pleistocene climate slightly cooler and drier than the present. Deforestation by people occurred mainly between 1200 and 800 yr BP. This may have led to an ecological disaster and to the decline of the megalithic civilization. The depauperation of the present native flora owes more to human activity than to isolation. Journalof Quaternary Science