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Glacial Cycles and Astronomical Forcing

Science  11 Jul 1997:
Vol. 277, Issue 5323, pp. 215-218
DOI: 10.1126/science.277.5323.215

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Abstract

Narrow spectral features in ocean sediment records offer strong evidence that the cycles of glaciation were driven by astronomical forces. Two million years ago, the cycles match the 41,000-year period of Earth's obliquity. This supports the Croll/Milankovitch theory, which attributes the cycles to variations in insolation. But for the past million years, the spectrum is dominated by a single 100,000-year feature and is a poor match to the predictions of insolation models. The spectrum can be accounted for by a theory that derives the cycles of glaciation from variations in the inclination of Earth's orbital plane.

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