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Geologic and Geophysical Maps and Volcanic History of The Kelton Pass SE and Monument Peak SW Quadrangles

MP-16-1DM CD Insert

By:Tracey J. Felger, David M. Miller, Victoria E. Langenheim, and Robert J. Fleck

The Kelton Pass SE and Monument Peak SW 7.5′ quadrangles (NW Utah) are located entirely within southern Curlew Valley, which drains south into Great Salt Lake, and extends north into Idaho. Bedrock exposures form the Wildcat Hills and two small shield volcanoes. Exposed rocks and deposits are Permian to Holocene in age and include sandstone of the Permian Oquirrh Formation, tuffaceous sedimentary rocks of the Miocene Salt Lake Formation, Pliocene basaltic and dacitic lava flows, Pleistocene rhyolite and basalt, and Pleistocene and Holocene surficial deposits of alluvial, lacustrine, and eolian origin. Structures related to the Miocene Raft River detachment fault and Basin and Range extension also are present. New geophysical data and interpretations and new geochronology data for volcanic units improved insight into the tectonic and volcanic evolution of the area.

The setting sun illuminates the Jurassic-age Navajo Sandstone cliffs of Cougar Mountain (right) and South Guardian Angel (left) as viewed from Kolob Reservoir Road. Here, the road travels on top of the 220,000- to 310,000-year-old Grapevine Wash lava flow (dark rocks in middle ground). Zion National Park, Washington County, Utah Photographer: Adam McKean; © 2015

POTD November 3, 2015: Zion National Park, Washington County, Utah

POTD 11-3-15 Zion National Park

Zion National Park, Washington County, Utah
Photographer: Adam McKean; © 2015

The setting sun illuminates the Jurassic-age Navajo Sandstone cliffs of Cougar Mountain (right) and South Guardian Angel (left) as viewed from Kolob Reservoir Road. Here, the road travels on top of the 220,000- to 310,000-year-old Grapevine Wash lava flow (dark rocks in middle ground).

POTD May 2, 2014: Bentonite Hills, east of Capitol Reef National Park, Wayne County, Utah

Bentonite Hills, east of Capitol Reef National Park, Wayne County, Utah
Photographer: Tyler Knudsen; © 2012

Black volcanic boulders litter colorful but seemingly lifeless badlands formed in the Brushy Basin Member of the Late Jurassic Morrison Formation. Moisture-sensitive swelling clays, formed by the alteration of volcanic ash, allow little vegetation to take root.