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Graph of Ice Volume on the Earth



This graph shows the general trend of changing ice volume on the Earth over the past 750,000 years. The extent of ice is estimated using changes in the amount of different isotopes of oxygen found in the calcium carbonate shells of planktonic sea creatures (foraminifera). These data are from Imbrie and others (1984). The portions of the curve marked with "G"s are times when glaciers may have reached into the midwestern U.S. The timing of midwestern U.S. glacial advances prior to 40,000 years ago are not well known. The advances indicated on this graph are taken from Richmond and Fullerton (1986).
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http://www.museum.state.il.us/exhibits/ice_ages/specmap_graph.html, Last modified August 30th 2007, 02:59PM.