Thomas Range, Juab County, Utah
Photographer: Jim Davis; © 2012
Layered volcanic rocks of the Topaz Mountain Rhyolite weather into interesting shapes. The rocks, referred to as stratified tuff, formed as ash fell from the sky and flowed across the ground during the explosive eruption of a volcanic caldera around 7 million years ago.
The Utah Geological Survey (UGS) is a division of the Utah Department of Natural Resources. Several specialized programs comprise the UGS: Data Management, Energy & Minerals, Geologic Hazards, Geologic Information & Outreach, Geologic Mapping, Groundwater & Wetlands, and Paleontology.
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