HYDROLOGY AND PALEOHYDROLOGY OF WINDY MOUTH CAVE, WEST VIRGINIA: AN ABANDONED SPRING CONDUIT ON THE GREENBRIER RIVER

The Greenbrier Valley of West Virginia is located near the eastern edge of the Appalachian Plateaus physiographic province. It is a broad limestone terrane that is heavily karstified. Sinkholes densely cover the region, and low-order surface drainage is nearly absent. Hundreds of caves are known, many of which are 10's of kilometers in length. The Greenbrier River, with a mean daily discharge of 60 cubic meters per second, serves as regional base level for the hydrologic system. The river is incised 115 meters below the main surface of the valley.

Windy Mouth Cave is a 11 km long series of interconnected conduits, generally North-South oriented, that are developed in the Hillsdale and Sinks Grove Limestones. The cave opens on the southern wall of the Greenbrier River gorge, 30 meters above the present river level. The position and orientation of the cave indicate that it once served as a groundwater conduit supplying a now-abandoned spring on the river. Although water is found in some portions of the cave, it has for the most part ceased to function as a major groundwater drain.

Using survey data that had been collected over a 30-year period, we constructed a digital three-dimensional model of the conduit system. This was used to investigate the relationship between conduits, structural features, topography, and hydrology. The northern part of the cave is essentially horizontal, and follows bedding. In the central part of the cave several canyons which cross-cut the main conduits, and incise in to the underlying Maccrady Shale, are found. In the southern part of the cave faulting has resulted in near-vertical bedding. Here the conduits ascend towards the land surface, and flowing water is present. Sand- to gravel-sized clastic material is found in the presently dry northern part of the cave. This attests to a time when a large opening to the surface must have provided water and sediment from a now extinct surface source. Based upon the elevation of the paleo spring mouth above the river (30 m) and a regionally calculated downcutting rate (0.06m/ka), this conduit may have been active at 500 ka.