DYE TRACE INVESTIGATION OF THE THERMAL KARST SYSTEM OF FALLING SPRINGS COVE IN WARM SPRINGS, VIRGINIA

Falling Springs Cove in Alleghany County, Virginia, contains a thermal karst system characterized by its complex geology and unique hydrogeologic features. Warm River and Mud Pot Caves, two of the three known caves in Virginia with a mixture of thermal and meteoric waters are located in the southern part of the valley near Falling Springs waterfall. Groundwater flow paths were delineated by water tracing with fluorescent dyes. that included six injection points. Eight sampling stations (five in caves) were monitored qualitatively with carbon detectors (dye traps) and Falling Spring was also monitored quantitatively from collected water samples. The dye traces indicated a predominantly southwestward flow of groundwater that is likely controlled by the overarching southwestward plunging anticline and the parasitic folds, faults, fractures, and caves that all act as conduits, directing water throughout the valley. Three tests that were started on the southeastern limb of the anticline were recovered in Warm River Cave and at Falling Spring on the western limb of the anticline. Two traces from sinks on the northwestern limb established hydrologic connections to Rushing Waters Cave and then to Warm River Cave and Falling Spring. All of the sinking streams tested so far were found to flow through Warm River Cave and return to the surface at Falling Spring. This indicates the waters in Warm River Cave and Mud Pot Cave are likely a mixture of deeply circulating thermal water and meteoric water highlighting the complex hydrogeology of this karst system.