The Transantarctic Mountains
July 03, 2001
Many glaciers such as this spill into the dry valleys of the Transantarctic Mountains from the Antarctic icecap. A bleak, flat, U.S.-sized ice plateau covers 95% of Antarctica. However, the Transantarctic Mountains act as a dam to keep back the encroachment of the icesheet. Where the icesheet is higher than the mountains, it flows into the valleys, eroding them further. Most of these glaciers ablate away without any outlet streams long before they reach the far end of the valley.
Because of Antarctica's unique environment, several interesting geologic features can be seen in this picture. 1) The constant flow of a glacier from its source, with flow lines visible where the glacier turns near the bottom of the image. 2) The vast Antarctic icecap in the background. 3) The eroding power of a glacier (it has eroded a large horshoe bend out of the surrounding mountains). And 4) The resistance to erosion of different rock types. The dark brown basalts are more erodable than the blocky sandstone cliffs they overlay, leaving the valley floor covered in basalt rubble.