The Kansas Historical Marker stands within a geological 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. Like several other smaller sinks in this section of Kansas, Big Basin was formed thousands of years ago by dissolving and collapse of massive gypsum and salt formations lying several hundred feet below the surface.

Highway 283 bisects the Big Basin traversing 1.04 miles through the basin before climbing to the rim, which has nearly vertical walls. The entrance to the Big Basin Prairie Preserve lies in the bottom of the basin, which is home to a free roaming buffalo herd. Visitors are urged follow the unimproved road to St. Jacob's Well, but to use caution when exiting their vehicles as these animals are unpredictable.

Approximately two-thirds of the basin lies east of the road within the confines of the preserve. The remaining western third of the basin is privately owned.