The Big Basin Prairie Preserve is a 1,818 acres (7.36 km2; 2.84 sq mi) nature preserve owned and managed by the Kansas Department of Wildlife and Parks. The preserve is in the Red Hills near Ashland in Clark County, Kansas. The main features are St. Jacob's Well, a water-filled sinkhole which lies in the Little Basin, and the Big Basin, a lush mile-wide crater-like depression, also resulting from a sinkhole. The area is stocked with buffalo and is open to the public. Elevations on the preserve range from 2,200 feet (670 m) to 2,360 feet (720 m) above sea level.