Saturday, December 20, 2008

Victoria Valley

From Taylor Valley we moved to Victoria Valley which is further north at an elevation of 400m. Victoria Valley has two glacier at either end and there is evidence that it was covered by a very large lake about 10,000 years ago. We also have a climate station here and we will drill in the permafrost to investigate the nature of the ice in the ground.
It is much dryer in Victoria Valley than in Taylor Valley. Snow only occurs occasionally in polygon cracks and depressions. The polygonal pattern ground in Victoria Valley is very impressive. Some of the polygon shoulders are 1 to 1.5 m high.

In addition to taking long cores we also use a small rock drill to take samples from the upper 15 to 20 cm of the groundice. The picture below shows Ron and David opening a pit at the shoulder of a polygon from which they retrieve a small ground ice core (see second picture below). The ground ice here occurs in two different forms: as ice cemented sand and pure ice (light part). Ice cemented sand has only small fraction of ice and consits mostly of sand while the pure ice contains only little or no sediment.

The last days we have strong katabatic winds which generate on the Antarctic Ice Sheet. They warm up due to increasing atmospheric pressure from the Ice Sheet (3000 m elevation) to the valley at 400 elevation; temperature increases can be 10 to 20 degrees. The lenticular cloud in the picture below indicats the winds.

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