Short description: Spalled Ogallala Formation mortar beds near Big Basin in Clark County. Big Basin is a circular depression about one mile across and 100 feet deep and is bisected by U.S. Highway 283/160. The floor of the basin is relatively flat. The 1,818-acre Big Basin Prairie Preserve features native mixed-grass prairie, rolling hills, small canyons, intermittent Keiger Creek, and a herd of bison that helps maintain the natural prairie ecosystem.
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