The Cody Scarp is the erosional edge of the Hawthorn Group rocks (Scott, 1988; Scott, 1992) and represents a location of intense recharge of surface water to the Floridan aquifer system via sinking streams and sinkholes (expressed at the surface), and in certain areas controls the water chemistry in and dissolution of the aquifer (Upchurch and Lawrence, 1984).
The Cody Scarp region approximates the transition area between the confined and unconfined Floridan aquifer system. In the Northern Highlands, the Floridan aquifer system is overlain by a thick layer of clay that recharge into the aquifer. To the south and the west of the Cody Scarp, the Floridan aquifer system is generally unconfined in the Gulf Coastal Lowlands. The clay units are generally absent (or very thin where present) in the Gulf Coastal Lowlands and recharge to the Floridan aquifer system is relatively high.
When sea level was higher and the Cody Scarp area represented the coastline, the clay confining layer was eroded away by wave action and ocean currents. When sea levels receded to the present day shoreline, it helped to create the perfect geological conditions for a combination of headward erosion by streams as well as the dissolution of carbonate rocks by both streams and groundwater. This enabled the development of some of the unique karst features we have here in the Suwannee River Water Management District including the many springs, sinks, swallets, karst windows and underground rivers. In fact, every single river that crosses the Cody Scarp in our district goes underground, and reemerges downstream as a spring, with the sole exception of the Suwannee River itself. A prime example of this would be the Santa Fe River. At O'Leno State Park the entire Santa Fe River is swallowed up by a sink as the river crosses the Cody Scarp, it then travels underground through a network of cave passages for over three miles before re-emerging at a spring in River Rise Preserve State Park.