Friday, August 9, 2013

Greenland's glaciers

If you happen to visit Greenland and gaze across the earth near Upernavik (IMAGE ABOVE), you would be looking at land that appears much the same as it did 800,000 years ago. While not exactly primordial, that time frame predates human occupation by 795,487 years. Graduate student Lee Corbett at the University of Vermont (and now Dartmouth) led a team of geologists in determining how old the surface was and why it remained so unchanged, although their trained eyes could immediately see that it was ancient: "Even before I dated these rocks, standing on the land surface, it was all crumbly and falling apart. The rocks are breaking off into sheets, and there are weathering pits on the surface. It's obviously a landscape that has experienced a much longer duration on the Earth's surface. It's a gorgeous landscape." In addition to reaching a date by means of counting isotopes, and determining that the land had been covered by ice and exposed at least 8 times, they figured out that the ice in the highlands did not melt and move and thus could not apply the erosive force that has scoured and shaped other landscapes. Hence the name "ghost glaciers."


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