Written 28 Dec 2007
3672 meters above sea level
Maximum & Minimum temperatures: - 26 to -35 °C
We have selected site 33 as a science stop for a chance to have a closer look at some unusual scenery.
That there is immense variety in the details on this uniform, white plain does not mean that we do not appreciate the unusual. On this location the satellite images show a series of large-scale ripples in the snow, and we have been curious about their origin. High in expectations we stopped here last evening. Sure enough, some kilometers out west we could see a long shadow under the horizon. A slope! Two of us went out to have a closer look and take some radar profiles, and found the ripples to be several elongated rises, up to 5 kilometers long, running in parallel and separated by valleys about one kilometer wide. The valleys were so deep that we even lost the view of our camp when driving through them. For a little while, the view was dominated by the towering hills, rising to as much as 7 meters above the valley bottoms!
For the Antarctic Plateau this is scenery as wild as it comes. But we are not here only to admire the stunning views. The very existence of these hills and valleys has yet to be explained. One theory is that they are created by bedrock topography under the ice sheet. The ripples could be created as the ice flows slowly over mountain peaks underneath the ice — much like submerged rocks create standing waves in fast water currents. But the more likely explanation is that these ripples, like other wavelike surface patterns elsewhere in Antarctica, are created by subtle differences in precipitation and wind patterns. Given the right conditions, initial roughness on the snow surface will trigger the build-up of dunes, as snow is deposited by the wind on the windward side and eroded off the leeward side. This theory is supported by the fact that we can find substantial sastrugi on the windward side of the hills and a more level and eroded surface, at times almost glazed, on the leeward side.
Image caption: The Hills of 33 as they appear in a Landsat satellite image. The asterisk and red line mark our camp and the track in from the north.
This contribution is from the log of the Norwegian-US Scientific Traverse team, who are en route from Troll Station to South Pole Station. Much more information can be found here.
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Saturday, 29 December 2007 22:20
Norway-US Traverse: Ice waves on the PlateauWritten by US-Norway Traverse
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Comment Link Tuesday, 30 November 1999 00:00 posted by Mark McCaffrey
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