THE POTENTIAL FOR ALLOGENIC RECHARGE TO CLEVERSBURG SINK CAVE, SOUTH CENTRAL PENNSYLVANIA

Cleversburg Sink Cave is located in the Great Valley of the Appalachians in south-central Pennsylvania. Cave surveys from the 1950s show linear passages that have developed along joints in highly deformed Ordovician limestones. Unfortunately, the surveys did not include a vertical component, so the system’s elevation, with respect to the water table and a nearby ephemeral surface stream, has never been known. Recent surface and sub-surface surveys, though incomplete, indicate that most of the cave lies below the stream channel that NSS cavers have blamed for the rapid flooding of the cave and persistent high water levels. These leveling surveys now link water levels, specific conductivity, and temperature collected by InSitu Troll 200 loggers placed in the cave and in the stream.

Potential allogenic recharge originates on siliceous Blue Ridge rocks and flows 4 km over colluvium-mantled carbonates to Cleversburg Sink. Storm events reveal a sudden rise in cave water levels (by as much as 7 m), and a drop in specific conductivity from +300 µs to <100 µs, the latter being characteristic of the allogenic waters. The events show no evidence of a piston effect, and high cave water levels tend to retain a specific conductivity similar to the surface waters suggesting continuous flow through the cave system. We speculate that a swallet, or losing reach of the stream, just downstream of the cave injects allogenic water, which acts to control cave water level and relatively low levels of dissolved solids. We anticipate future injection of dye to a swallet that may provide a positive linkage.