POTENTIAL RECONCILIATION OF DEVILS HOLE AND DEEP-SEA PLEISTOCENE CHRONOLOGIES

The standard model of Pleistocene climate fluctuations being driven by orbital insolation changes has been challenged by results from a high-precision, radiometrically dated deposit from Devils Hole, Nevada. Although the Devils Hole record agrees with a previously derived ice volume record for most of the last 500,000 years, clear indication of warming prior to the orbitally dated onset of the last interglacial forms the prime basis for this conclusion. I suggest that ''early warming'' at Devils Hole needs to be understood in light of the prior very extensive glaciation at 150,000 B.P. Marine records in both the North Pacific and North Atlantic, from the same latitude as Devils Hole, indicate that the subpolar fronts during the penultimate glaciation (150,000 years ago) were 5-degrees father south than during the last glaciation. Continental glaciation may also have been more extensive at this time. The first phase of ice retreat approximately 145,000 years ago is associated with a northward shift of these fronts, which results in full-interglacial sea surface temperatures in the North Atlantic. The early warming at Devils Hole may reflect the northward movement of the ice margins and associated fronts. If so, both the Devils Hole and deep-sea chronologies may be correct, with differences between 130,000 and 150,000 years ago reflecting a regionally varying response to climate shifts associated with a very extensive glaciation.