The Art of Making Mountains

The Art of Making Mountains. . , A landscape built up by earthquakes, The spectacular Teton Range began to rise around ten million years ago when movement on the Teton fault generated a series of massive earthquakes. The block of bedrock west of the fault rotated skyward to form the mountains and the block east of the fault hinged downward to form the valley of Jackson Hole. One day, another earthquake will continue this process., Today the mountains tower more than 7,000 feet above the valley floor. Across Jackson Lake, the 40-mile-long Teton fault marks the abrupt transition between the steep mountain face and the flat valley floor., Worn down by glaciers and erosion, Beginning some two million years ago, a series of glaciers flowed down from the high peaks and south from Yellowstone. These glaciers, their bases studded with rocky debris, ground and polished bedrock, carved U-shaped canyons, and dug out basins. The receding glaciers left behind moraines, ridges of boulders, gravel, and rock flour that form natural dams around the valley’s lakes. Jackson Lake is more than 400 feet deep, evidence of the power of glaciers to change the landscape., Water, wind, and ice continue eroding the mountains, although with less power than during the ice age. Today’s small glaciers formed around 1400 and are currently receding, mere shadows of their ancestors. , Date Event Effect. Two million years ago . Start of the Pleistocene Ice Age . Ice up to 3,500 feet thick on northern parts of Jackson Lake , 170,000 to 120,000 years ago . Bull Lake glacial period . Glacier about 1,800 feet thick covered Jackson , 500,000 to 14,000 years ago . Pinedale glacial period . Glaciers carved out lakes such as Jenny and Jackson , 1,400 to 1850 AD . Little Ice Age . Skillet, Falling Ice, and Teton are largest remaining glaciers