Dec 5 1976
From The Space Library
The fundamental cause of the succession of Ice Ages undergone by the earth had been the slight but regular changes in the shape of earth's orbit around the sun, according to a team of U.S. and British scientists headed by Dr. James D. Hays of Columbia Univ. Analysis of layers of fossil microorganisms from cores of sediment taken from the floor of the Indian Ocean produced measurements of the earth's climate over the past 450 000 yr; changes in climate appeared in alternating layers of warm- or cold-preferring microfossils, known as radiolaria. The discovery should permit prediction of the onset of the next Ice Age, although the cooling trend now in process should continue for about 20 000 yr. The last great glaciation 18 000 yr ago brought ice down over most of Canada, northern Europe and Asia, and the northern U.S.; it was one of eight major Ice Ages over the past 700 000 yr. The ice retreated about 11 000 yr ago to its present boundaries, and the earth is now in a warmer period. The investigation, to be reported formally in the 10 Dec. issue of Science magazine, was supported by a consortium of universities and the Natl. Science Foundation. (NYT, 5 Dec 76, 4-14; C Trib, 5 Dec 76, 1-9)
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