Did it melt or not? Antarctic scientists, including a team in UMaine's Institute for Quaternary Studies and Dept. of Geological Sciences, have been debating that question for more than a decade when they look at the history of the south pole ice sheet as far back as three to four million years ago. The answer is important for predicting how Antarctica and the world's ocean levels might behave in a warmer global climate.
In the Journal of Geology, (1997, vol. 105, p. 285-294), a UMaine team has published new evidence consistent with the view that the East Antarctic ice sheet remained stable during that period and did not melt as other researchers have suggested.
Co-authors Brenda Hall, George Denton and Daniel Lux are at UMaine and Christian Schluchter is with the University of Bern in Switzerland. Their work was funded by the National Science Foundation and the National Oceanic and Atmospheric Administration.
The team reached its conclusions by evaluating geologic evidence in an area known as the Dry Valleys. The area has been a Mecca for geologists because the valleys lack the ice and snow which cover most of the continent.
In Wright Valley, researchers surveyed rocks on the ground and excavated pits to determine the nature of underlying layers. Their results reflect past movement by glaciers which extend into the valley from surrounding mountains.
"Working conditions could be considered harsh," says Hall. "We live in tents in small camps of two to five people for 100 days each season. Temperatures range from -20 to +40 degrees F. Winds, which are sometimes very strong, blow almost constantly. However it is a very beautiful and unspoiled place to work."
Under Denton's leadership, the team continues to work in this area on a project to determine when a full-scale polar ice sheet first developed in Antarctica.
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