HYDROGEOLOGY NEAR CLIFTON, VA

The Little River, a tributary of the Clinch River, lies within the Ordovician karst of Russell and Tazewell counties, Virginia. Geologic units in the area have not been well mapped, however in the vicinity of Clifton, carbonates of the stratigraphically lower Knox Group and of the Moccasin Formation are exposed along the SE trend of the stream. These beds strike generally northeast-southwest and dip to the southeast. A ridge, probably composed of Moccasin limestone, is initially drained by surface water, which sinks along the contact with carbonates of the Knox Group. Water resurges in a few springs along the valley floor. A major resurgence point is the entrance to Trooper Said cave, which lies near the river. Water emerging from the cave enters Little River a short distance from the cave entry. An initial field survey led to the hypothesis that insurgence of water in two sinks near the base of the ridge was flowing along the contact between the Moccasin and Knox units and re-emerging through Trooper Said cave. After detailed study of satellite data, it became apparent that water might be flowing from the Little River into Trooper Said cave, then reentering the stream. Two alternate hypotheses were developed; that water was flowing perpendicular to the strike of the formations, directly to the river through underground fractures or that water was flowing partially along the contact between formations before turning across strike to enter the stream. In both cases, water would enter Little River upstream of Trooper Said cave. Fluorescent dye tracing was used to determine the flow path, confirming the initial hypothesis that water was travelling along the contact between units and entering Little River via Trooper Said cave.