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Smith Professors Document Unusual Interglacial Sea-Level ChangeSmith College professors Allen Curran and Brian White have documented a sea-level change resulting from a "little ice age," which occurred during an interglacial period in the Pleistocene Period. While working on the islands of San Salvador and Great Inagua in the Bahamas with colleague Mark Wilson, a professor at the College of Wooster, the geologists discovered a distinctive, gently undulating erosion surface, which represents a sea-level change that lasted about 1,500 years or less, in the midst of reefs that had formed about 124 to 125 thousand years ago. Curran and White carefully mapped the fossil coral reefs above and below the surface. With the use of uranium/thorium-dating techniques, they determined the precise age of the corals. The erosion surface in the middle of these corals shows evidence of having been bored by a variety of clams and sponges and contains surface remnants of ancient soil. According to White, who presented the trio's findings at the annual meeting of the Geological Society of America held last month in Salt Lake City, "This is evidence that rapid sea-level changes occurred, yielding proof of rapid changes in global ice volume and temperatures. It emphasizes that the interglacials were not ice-free but only reflected ice sheet areas and volumes." According to Curran, the evidence correlates with ice core data collected by scientists in Greenland that show a 9-degree-Celsius drop in global temperatures just before the change in sea level recorded in the rocks of the Bahamas: "Our findings should be an important caution to all of us living during the Earth's current interglacial period not to be so cavalier about our experiments with global biosphere-atmosphere-ocean systems." The three scientists note that their discovery of an unexpected "little ice age" during the interglacial period is further evidence that ancient climate models are much more complex than previously thought. |
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