On U.S. 160 at milepost 138, on the left when traveling south.
This marker stands within a geologic feature known as the Big Basin, which is a sinkhole or "sink" about a mile in diameter and more than a hundred feet deep. Although it has the appearance of a valley, it is entirely surrounded by higher ground. . . . — — Map (db m11565) HM
On U.S. 283, 3 miles south of U.S. 160, on the right when traveling north.
Big Basin Prairie Preserve is a 1,818-acre nature preserve managed by the Kansas Department of Wildlife, Parks & Tourism. It is named after the large collapse basin or sink just north of here. This 1-mile diameter, 100-foot deep basin was formed . . . — — Map (db m192091) HM