DYE-TRACING STUDIES IN A KARST TERRAIN IN MISSISSIPPIAN STRATA OF THE CUMBERLAND PLATEAU IN SOUTH-CENTRAL TENNESSEE

Lost Cove is a large (1700 hectares) solution valley with over 220 meters of relief formed in Mississippian carbonates on the flanks of the Cumberland Plateau near Sewanee, Tennessee. It is thought to be drained exclusively by a large sinkhole (Big Sink) at the lowest point of the valley. Flat-lying Mississippian strata consist of (from oldest to youngest) the Monteagle Limestone, Hartselle Formation, Bangor Formation and Pennington Formation. All formations, with the exception of the Hartselle Formation, are typified by an extensively developed karst system. The Hartselle Formation is a relatively impermeable calcareous sandstone and is known to be an impediment to groundwater flow and cave development throughout the southern Cumberland Plateau of Tennessee. It therefore acts as a boundary between an upper and lower karst system within this sequence of rocks. The flow of groundwater through the Lost Cove karst system has received very limited attention to date.

Dye-tracing studies were conducted using both fluorescein dye and FD & C Red #3 dye in order to characterize flow through the karst system. A positive, sub-surface flow connection was made between a large sinkhole in the Bangor Formation on the flanks of Lost Cove and four springs emanating from the Monteagle Limestone at he base of Lost Cove some 2.75 km away. This indicates that groundwater was able to move through the normally impermeable Hartselle Formation to the lower karst system and suggests that the idea of separate upper and lower karst systems does not apply in Lost Cove. Dye placed into a sinkhole in the Monteagle Limestone on the lower slopes of Lost Cove failed to appear anywhere in Lost Cove, suggesting that there may be other, previously unknown drainages in the Cove other than the Big Sink.