Tag Archive for: Wasatch Plateau

SS-155 insert

By: Greg N. McDonald and Richard E. Giraud

This map represents a landslide inventory for the upper Muddy Creek area, Sanpete and Sevier Counties, Utah, at a scale of 1:24,000. The map covers 54 square miles on southern part of the Wasatch Plateau and includes the Beaver Creek and Horse Creek Hydrologic Units in the east-southeast-draining Muddy Creek headwaters. The map and accompanying geodatabase show and characterize landslides and provide information useful for managing landslide-related issues. Spatial and tubular data for each landslide are stored in the geodatabase and linked to the inventory map. Landslide information in the geodatabase includes: area, material type, movement type, landslide deposit name, landslide source name, movement activity, thickness, movement direction, approximate movement dates, geologic unit(s) associated with landsliding, confidence in mapped boundaries, mapper, peer reviewer, and general comments.


Have a fun weekend, everyone!

Skyline Drive, Wasatch Plateau, Sanpete County, Utah
Photographer: Rich Emerson; © 2012

At 10,133 feet, winter clings to outcrops of the Tertiary-age Flagstaff Limestone near the crest of the Wasatch Plateau at Snow Lake. The steep, forested slope to the left (east) of the lake is a scarp associated with one of several faults forming a down-dropped crustal block called the Snow Lake graben.


Ferron Mountain, Wasatch Plateau, Sanpete County, Utah
Photographer: Greg McDonald; ©2011

Fall colors at the base of striped layers of the Tertiary-age Flagstaff Limestone, southeastern end of Ferron Mountain, Wasatch Plateau, Sanpete County.

Wasatch Plateau, eastern Sanpete County, Utah
Photographer: Rich Giraud; © 2011

The lower part of the Slide Lake landslide has averaged 14 feet of movement per year between 2004 and 2009. The landslide occurred in the Tertiary-Cretaceous-age North Horn Formation, which is known for producing many large landslides. Near Joes Valley Reservoir, the 1.2 miles long landslide deflects Seely Creek.

Spinners Reservoir, Wasatch Plateau, Sanpete County, Utah
Photographer: Greg McDonald

Spinners Reservoir in the Muddy Creek drainage basin, Wasatch Plateau, Sanpete County, Utah

Twelvemile Canyon, Wasatch Plateau, Sanpete County, Utah.
Photographer: Rich Giraud

Island Lake at the head of Twelvemile Canyon, Wasatch Plateau, Sanpete County, Utah.

Hellmut H. Doelling, Paul A. Kuehne, and Douglas A. Sprinkel

The Ephraim quadrangle is located about 140 miles south-southeast of Salt Lake City in Sanpete County in central Utah. A diagonal line, extending NE-SW across the quadrangle, divides Sanpete Valley to the northwest, from the Wasatch Plateau. Sanpete Valley is a structural feature in which the San Pitch River flows south along its west margin. Quaternary fans form a gently sloping surface from the plateau front to the floodplain of the river.

Bedrock units are mostly of early Tertiary age. These include the (ascending) North Horn Formation (1100+ feet thick), Flagstaff Limestone (500–1000 feet thick), Colton Formation (1400+ feet thick), Green River Formation (620+ feet exposed), and the Crazy Hollow Formation (less than 50 feet exposed). Of these, the North Horn Formation may also have some Late Cretaceous strata at the base. The older three units are exposed in the Wasatch Plateau, the other two along the plateau-valley margin.

35 p., 1 pl., scale 1:24,000

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geosights-fanatsy-canyonGeologic Information: The sandstone layer in which the pinnacles, pillars, arches, and knobs of Fantasy Canyon are formed consists of ancient river channel sediments. The underlying and overlying rock layers sandwiching the sandstone layer, and creating scenic badland topography around the canyon, are finer grained floodplain deposits.

During the Eocene Epoch, 55 to 34 million years ago, the Fantasy Canyon area was at the fringe of a vast subtropical lake – Lake Uinta – that at peak level stretched from the Wasatch Plateau to western Colorado. The lake was in a drying phase and retreating westward by the end of the Eocene.