Geodiversity atop Utah’s Velvet Ridge

May 27, 2021

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Photographer: Ray Boren 

Summary Author: Ray Boren 

Velvet Ridge is a stretch of cliffs and other eye-catching formations that rise above the Fremont River between the small rural towns of Torrey and Bicknell in south-central Utah, west of Capitol Reef National Park. The ridge and the park share many of the same characteristics of geodiversity, which the National Park Service defines as a range of geologic resources, encompassing rocks, sediments, minerals, fossils, landforms and physical processes.

The first photograph here, taken on April 8, 2021, showcases colorful features of the High Plateaus Section of North America’s vast Colorado Plateau, ranging from the sandstone cliffs in the high background, which in this region record 275 million years of Earth’s past, as well as evidence of ancient volcanism. The tinted clay in the foreground is bentonite, well-known in the nearby park. This formation is composed of volcanic ash, as well as silt, sand and mud, deposited in lakes and swamps during the Jurassic, 145 to 201 million years ago.

And then there’s that perplexing scatter of big black boulders, peppering red and white rock as well as lying atop the cracked clay slopes. The area’s boulders came from basalt and andesite cliffs on nearby Thousand Lake Mountain (elevation 11,300 ft/3,444.2 m) and Boulder Mountain (11,317 ft/3,449 m), both prominent high plateaus. Elongated Boulder Mountain is visible to the south, across the valley of the Fremont River (also visible) in the second photo, also taken from atop the rim of Velvet Ridge on April 8. Geologists believe small Ice Age glaciers cut and quarried the high cliffs, and then erosion — via rockslides, landslides, meltwater streams and flash floods — over time distributed the boulders hither and thither across the complicated landscape.