Aside from the natural beauty of the rugged terrain and the abundant wildlife, the geologic formations in the Old Jamestown Area are unique. The underlying karst limestone formations are reflected on the surface by sinkholes created after hundreds of thousands of years of a critical combination of underground water flow, dissolvement of the limestone, the weight of the overburden soil, collapse of the soil/rock structure, and then surface runoff water flowing into the ground openings to cause further erosion. More than four square miles of the Old Jamestown Area have been identified by the Missouri Department of Natural Resources as karst formations. Their report, after a field investigation in February 1988, said, "The karst area is so unique; preserving its natural state as much as possible would certainly be desirable."

The significance of what is generally referred to as the "Florissant karst" is well documented by virtually every book on Missouri geology. Taken from the Land Element of the St. Louis County 1973 General Plan..."The Florissant karst is recognized as having the finest example of deep funnel-shaped sinkholes in the Central United States."

The karst formation will always be active. Taken from the Old Jamestown Association Position Statement of September 4, 1987..."Most people think of sinkholes as a geological feature that has occurred during the past thousands of years. That is true in some cases, but it is also true that sinkholes constitute a continuously changing configuration of the surface in a karst terrain. We are prepared to show you sinkholes that have recently occurred, ponds that have drained because of sinkholes, the effects of creep as the sides of sinkholes move laterally into the holes, and forty foot deep ravines eroded by surface water drainage into sinkholes." (A copy of the Position Statement, which includes an extensive segment about sinkholes, is provided with initial membership, $3.00 for additional copies.)