Geography

Basin and Range Province

Rows of fault-block mountain ranges follow a north–south alignment in this province in the Great Basin west of the Wasatch Range [1] and the High Plateaus. Most of the land lies at elevations between 4,000 and 5,000 feet. Peaks in the Stansbury and Deep Creek Mountains rise more than 11,000 feet above sea level, creating “biological islands” inhabited by cool-climate plants and animals.

Erosion has worn down many of the ranges, forming large alluvial fans in adjacent basins. Many of these broad valleys lack effective drainage, and none have outlets to the ocean. Terraces mark the hills along the shore of prehistoric Lake Bonneville, which once covered most of this province. Few perennial streams originate in these rocky mountains, but rivers from eastern ranges end their voyages in the Great Salt Lake, Sevier Lake, or barren silt-filled valleys.

Middle Rocky Mountains Province

The Wasatch Range [1] and the Uinta Mountains, which form this province, provide some of the most dramatic alpine scenery in the state. In both mountainous areas, you’ll find cirques, arêtes, horns, and glacial troughs carved by massive rivers of ice during periods of glaciation. Structurally, however, the ranges have little in common. The narrow Wasatch, one of the most rugged ranges in the country, runs north–south for about 200 miles between the Idaho border and central Utah. Slippage along the still-active Wasatch Fault has resulted in a towering western face with few foothills. Most of Utah’s ski resorts lie in this area. The Uinta Mountains in the northeast corner of the state present a broad rise about 150 miles west–east and 30 miles across. Twenty-four peaks exceed 13,000 feet, with Kings Peak (elev. 13,528 feet) the highest mountain in Utah. An estimated 1,400 tiny lakes dot the glacial moraines of the Uintas.

Colorado Plateau Province

World-famous for its scenery and geology, the Colorado Plateau covers nearly half of Utah. Elevations lie mostly between 3,000 and 6,000 feet, but some mountain peaks reach nearly 13,000 feet. The Uinta Basin forms the northern part of this vast complex of plateaus; it’s bordered on the north by the Uinta Mountains and on the south by the Roan Cliffs. Although most of the basin terrain is gently rolling, the Green River and its tributaries have carved some spectacular canyons into the Roan and Book Cliffs. Farther south, the Green and Colorado Rivers have sculpted remarkable canyons, buttes, mesas, arches, and badlands.

Uplifts and foldings have formed such features as the San Rafael Swell, Waterpocket Fold, and Circle Cliffs. The rounded Abajo, Henry, La Sal, and Navajo Mountains are examples of intrusive rock—an igneous layer that is formed below the earth’s surface and later exposed by erosion. The High Plateaus in the Escalante region [2] drop in a series of steps known as the Grand Staircase. Exposed layers range from the relatively young rocks of the Black Cliffs (lava flows) in the north to the increasingly older Pink Cliffs (Wasatch Formation), Gray Cliffs (Mancos Shale), White Cliffs (Navajo Sandstone), and Vermilion Cliffs (Chinle and Wingate Formations) toward the south.