This book tells the exciting story of the ice ages--what they were like, why they occurred, and when the next one is due. The solution to the ice age mystery originated when the National Science Foundation organized the CLIMAP project to study changes in the earth's climate over the past 700,000 years. One of the goals was to produce a map of the earth during the last ice age. Scientists examined cores of sediment from the Indian Ocean bed and deciphered a continuous history for the past 500,000 years. Their work ultimately confirmed the theory that the earth's irregular orbital motions account for the bizarre climatic changes which bring on ice ages. This is a tale of scientific discovery and the colorful people who participated: Louis Agassiz, the young Swiss naturalist whose geological studies first convinced scientists that the earth has recently passed through an ice age; the Reverend William Buckland, an eccentric but respected Oxford professor who fought so hard against the ice-age theory before accepting it; James Croll, a Scots mechanic who educated himself as a scientist and first formulated the astronomic theory of ice ages; Milutin Milankovitch, the Serbian mathematician who gave the astronomic theory its firm quantitative foundation; and the many other astronomers, geochemists, geologists, paleontologists, and geophysicists who have been engaged for nearly a century and a half in the pressing search for a solution to the ice-age mystery.