A Teton is a defining feature of the Western United States, primarily recognized as a mountain range located in northwestern Wyoming. This chain of peaks rises abruptly from the valley floor, presenting one of the most iconic landscapes in North America. The term refers both to the mountains and the history of exploration in the region. The range is known for its sheer vertical relief, jagged granite summits, and forms the centerpiece of a major national park.
The Origin of the Name Teton
The name “Teton” originated with French-Canadian fur trappers in the early 1800s. They named the three most prominent peaks Les Trois Tétons, a French phrase meaning “the three breasts.” The rounded shape of the Grand Teton, Middle Teton, and South Teton, particularly when viewed from the east, inspired this comparison. This name was eventually simplified to “The Tetons.”
The Indigenous Shoshone people, who inhabited the area for over 11,000 years, had their own term for the peaks. The Shoshone word Teewinot translates to “many pinnacles,” describing the sharp, needle-like summits. Although the mountain range was named by the French, the name Teton also has a historical association with the Teton Sioux, a division of the Lakota people.
Defining the Teton Range and National Park
The Teton Range spans approximately 40 miles north-south along the border of western Wyoming and eastern Idaho. The Grand Teton, its most famous peak, stands at 13,779 feet (4,198 meters). The range lacks the typical lower-elevation foothills of other ranges, giving the impression that the peaks rise straight out of the valley floor. This results in a vertical relief of over 7,000 feet from the valley of Jackson Hole to the summit.
Grand Teton National Park protects much of the range. Established in 1929, the park was expanded in 1950 to include the valley floor, Jackson Hole, encompassing about 310,000 acres. This area connects to Yellowstone National Park to the north, forming part of the Greater Yellowstone Ecosystem. The park features large glacial lakes—including Jackson, Jenny, and Leigh—which lie at the base of the eastern slope.
The park conserves the natural scenery, wildlife, and historical objects for public enjoyment. It is a major destination for mountaineering, hiking, and wildlife observation. The preserved ecosystem allows species to roam and migrate between the Teton Range and Yellowstone, drawing millions of visitors annually.
The Geological Story of the Tetons
The Teton Range is a fault-block mountain system, relatively young in geological terms. Mountain building began about nine million years ago, driven by the Teton Fault, a massive, active normal fault along the eastern base. Crustal movement along this fault involves one block of the Earth’s crust moving up while the adjacent block moves down.
The western block rose to form the mountains, while the eastern block dropped to create the Jackson Hole valley. This process resulted in immense vertical displacement, estimated between 25,000 and 30,000 feet. The active normal fault explains the range’s sharp, un-eroded appearance. The core of the Tetons consists of some of North America’s oldest rocks, primarily granite and gneiss, dating back nearly 2.7 billion years.
Following the fault-block uplift, repeated glaciation during the Pleistocene Ice Ages sculpted the peaks. Vast ice sheets carved out deep, U-shaped canyons and gouged out bowl-shaped depressions known as cirques. Glacial movement created the sharp, jagged arêtes and horns that define the Teton skyline. Moraines left by the retreating ice impounded the major lakes at the base of the mountains.
Wildlife and High-Altitude Ecosystems
The steep elevation gradient supports diverse ecological zones, from the sagebrush flats of the valley floor to the sparse alpine environment of the high peaks. This area is a southern extension of the Greater Yellowstone Ecosystem, providing habitat for large mammals. Common sightings in lower elevations include herds of bison and elk grazing in the open grasslands during migration seasons.
Moose are frequently found browsing on willows in wetland areas and along streams fed by mountain runoff. Dense coniferous forests provide cover for predators, including grizzly and black bears, gray wolves, and mountain lions. Above the tree line, specialized animals like the yellow-bellied marmot and the pika thrive, adapted to survive the long, cold winters and short summers.