In fairly recent geologic times, slippage began to occur along a fault in the rocks. A large block of earth, 15 miles from east to west and 40 miles from north to south began to move upward. The block rose most rapidly on the east side and so was tilted to the west. As the Teton Range was being uplifted, water and frost wedging began to remove the topmost layers and expose ancient gneiss and schist. V-shaped valleys were formed. Then a change in the climate brought the onset of the Ice Ages. Glaciers sculpted the peaks and carved U-shaped valleys, leaving the mountains in their present magnificent form. A glaciated valley is visible on the left in this view. It still has a glacial remnant in it.
