America's National Parks and Road Trip Planning Find Your Park Road Trip Activities Nature

Grand Teton National Park Geology

Imagine visiting Grand Teton National Park 85 million years ago. You would see a much different landscape. Stretching before you would be a great inland sea, which deposited layers of sediment on top of 2.4 billion year old granites and 2.8 billion year old gneisses. Jump forward 25 million years; those seas have retreated, and a major event, the Laramide Orogeny, is forming the Rocky Mountains. The Teton Range lies hidden beneath the unbroken surface and is waiting for a much younger and different series of events. The Teton Fault spans the entire length of the Teton Range's eastern front. Sometime between two to thirteen million years ago marked the beginning of uplifts, accompanied by a series of a few thousand earthquakes along that fault. These sporadic bursts of energy created the abrupt front of the Teton Range as it faces Jackson Hole. At 13,770 feet, the summit of the Grand Teton towers nearly 7,000 feet above the valley floor.

Total vertical displacement along this fault has been close to 23,000 feet. The valley of Jackson Hole dropped 16,000 feet, more than twice as much as the mountains rose. The beauty of the Teton Range lies in its majestic size and rugged appearance. Beginning as early as 2 million years ago, glaciers scoured and sculpted the Teton landscape. Large masses of ice flowed from the topographic high of the Yellowstone Plateau down into the valley of Jackson Hole. Fingers of ice, pulled by gravity, flowed from the high Teton peaks down into the valley. Grand Teton National Park contains piedmont lakes, U-shaped canyons, knife-like ridges, kettles, moraines, and other glacial features. Grand Teton National Park, as it is today, boasts dramatic vistas and a geologic story that is by no means over. This story still involves active geologic forces including glaciers, but the Teton Fault lies dormant. There has been a gap in seismic activity along the fault, but eventually it will lurch into action. Imagine a rubber band that is stretched to its limit; sooner or later it will break. For the Teton Fault it is not a matter of if, but when, it will move again.

Adapted from "Windows into the Earth"

by Robert B. Smith and Lee J. Siegel

Featured Outdoor Gear

The FR-C Pro Thermal Bib Tight is your go-to bib tight for all-out efforts in milder climates....
Price subject to change | Available through

National Park Spotlight
Bryce Canyon National Park
Bryce Canyon National Park
Featured Wildlife
Maine Puffins
Maine Puffins

Maine ocean islands provide the only nesting sites for Atlantic puffins in the United States. Eastern Egg Rock in the midcoast region, Seal Island and Matinicus Rock at the mouth of Penobscot Bay, and Machias Seal Island and Petit Manan Island off the downeast coast provide habitat for more than 4,000 puffins each summer.