LATE-HOLOCENE FORMATION OF LAKE-MICHIGAN BEACH RIDGES CORRELATED WITHA 70-YR OSCILLATION IN GLOBAL CLIMATE

A radiocarbon-dated series of 75 beach ridges, formed at regular inter vals averaging 72 yr over the past 5400 yr, provides further support f or the existence of a 70-yr oscillation in Northern Hemisphere climate , postulated recently from instrument data representing less than two cycles of this climate oscillation. Results from this study lend suppo rt to the interpretation that internal variations in the ocean-atmosph ere system are an important factor in climate fluctuations on a decada l-centennial time scale. A temperature oscillation with a period of ab out 70 yr has been a previously unrecognized but fundamental part of t he global climate system since at least the middle Holocene. (C) 1996 University of Washington.