Grand Teton National Park, Wyoming

Grand Teton National Park is a United States National Park located in northwestern Wyoming, south of Yellowstone National Park. The park is named after the Grand Teton, which, at 13,770 feet (4,197 m), is the tallest mountain in the Teton Range.
The origin of the name "Teton" is not definitive. One possible origin is that it was the name given by French trappers in the area. ("Tetons" means breasts in French) Another possible source is that the mountains derive their name from the names of one of tribes in the Sioux Nation. Grand Teton National Park was established on February 26, 1929. The park covers 484 square miles (1,250 km2) of land and water.
There are nearly 200 miles (320 km) of trails for hikers to enjoy in Grand Teton National Park.

The rock units that make up the east face of the Teton Range are around 2500 million years old and made of metamorphosed sandstones, limestones, various shales, and interbeded volcanic deposits. Buried deep under Tertiary volcanic, sedimentary, and glacial deposits in Jackson Hole, these same Precambrian rocks are overlain by Paleozoic and Mesozoic formations that have long since been eroded away from atop the Tetons.

The Paleozoic-aged sediments were deposited in warm shallow seas and resulted in various carbonate rocks along with sandstones and shales. Mesozoic deposition transitioned back and forth from marine to non-marine sediments. In later Mesozoic, the Cretaceous Seaway periodically covered the region and the Sierran Arc to the west provided volcanic sediments.

A mountain-building episode called the Laramide orogeny started to uplift western North America 70 million years ago and eventually formed the Rocky Mountains. This erased the seaway and created fault systems along which highlands rose. Sediment eroded from uplifted areas filled-in subsiding basins such as Jackson Hole while reverse faults created the first part of the Teton Range in the Eocene epoch. Large Eocene-aged volcanic eruptions from the north in the Yellowstone-Absaroka area along with later Pleistocene-aged Yellowstone Caldera eruptions, left thick volcanic deposits in basins.

The Teton Range started to grow along a north-south trending fault system next to Jackson Hole some 9 million years ago in the Miocene epoch. Then starting in the Pliocene, Lake Teewinot periodically filled Jackson Hole and left thick lakebed sediments. The lake was dry by the time a series of glaciations in the Pleistocene epoch saw the introduction of large glaciers in the Teton and surrounding ranges. During the Last Glacial Maximum, these glaciers melded together to become part of the Wisconsin glaciation, which carried away all soil from Jackson Hole and surrounding basins. Later and less severe ice ages created enough locally-deposited material in the form of moraines and till to repair much of this damage. Since then, mass wasting events such as the 1925 Gros Ventre landslide, along with slower forms of erosion, have continued to modify the area. On the floor of the Jackson Hole valley rise several landforms, one of the most conspicuous being Blacktail Butte.



Note: This is No.13 of the series of articles on national parks in the US.