The Geology

Grand Teton National Park, Wyoming

The Rising Range

Rocky Mountain scenery offers dramatic vistas, but few more impressive than the Teton skyline. As the Teton Range rose through sporadic earthquake-producing jolts, the valley called Jackson Hole subsided. Because of the way the mountains were formed, no foothills hide jagged peaks and broad canyons. At the base of the range, large lakes mirror the mountains of calm summer days, doubling the prominence.

Water-cut Gorges & Canyons


Cascading water initially cut steep, V-shaped gorges throughout the rising range. Changes in the Earth's climate caused long periods when snowfall exceeded melting, precipitating glaciers in sizes beyond imagination. Glaciers advanced, and in warmer times receded, in mountain gorges and cut across the floor of Jackson Hole. Southward-flowing ice wore than 3,000 feet thick filled the valley, overriding buttes and surrounding mountains. Only the high Teton peaks protruded through engulfing ice. Mountain glaciers, particularly during the last Ice Age, widened steep gorges into broad, U-shaped canyons.

At upper elevations a dozen smaller glaciers slowly flow from the cirques cut by Ice Age giants.

The National Park Service included the illustrations on this page in the map given to visitors at the park entrances. If you would like more information on the park geology, here's a link to the Grand Teton geology page on their site.

Page last updated July 24, 2000.