Cascade Cave

Soil gas collecting tubes and lysometers to sample soil waters were installed at four locations above sampled drips in Cascade Cave (sites 16 and 17) and X Cave (sites 18 and 19) as shown on Fig. 3. Pco, measured from the gas wells and equilibrium Pco, in the water withdrawn from the lysometers was higher during the summer when plant growth was active and soil temperatures were high, and at any one time increased with depth. The Pco, of sandy soUs with higher permeability tended to be lower than clayey soils, and deep drying of the soils caused a decline in Pco, Some representative values are shown in Table II. 

The same conclusion may be drawn from the remaining sites 11—13 (Table I). Sites 12 and 13 are separated by only a few centimeters and were originally sampled together as site 11. These waters have so completely equilibrated to the Cascade Cave atmosphere that they furnish little information on their original chemistry, except to illustrate the slowness of the process by which calcite-supersaturated water attains saturation by precipitation. 

Water samples were collected in Mammoth, Cascade and X caves, and water and gas samples were collected from the soil overlying Cascade and X caves. Mammoth Cave is in west-central Kentucky and Cascade and X caves are 300km from Mammoth in northeastern Kentucky. Cascade and X caves are 3 km apart. AU three caves are developed in limestones of Late Mississippian age and are within a few hundred meters of the outcrop of overlying Upper Mississippian and/or Pennsylvanian sandstones and shales. 

The temperatures of both the Mammoth Cave and the Cascade and X caves areas are similar, with a January mean minimum of — 2°C and a July mean maximum of 32°C. The mean annual precipitation is 0.10 m in the Mammoth Cave area and 0.13 m in the Cascade and X caves area and is fairly evenly distributed over the year (Karen and Mather, 1977). 

Fig. 3. Index map and cross-sections showing location of sites. Dotted pattern shows capping sandstone and shale at Mammoth Cave and soil at Cascade and X caves.

Representative values of Pco2 Ca from soils above Cascade and X caves... 

Although considerable effort was expended in obtaining soil samples from the four sites overlying sampled drips in Cascade and X caves, the numerous difficulties encountered precluded the collection of large amounts of data. These difficulties included dilution from higher water sources, absence of sample due to low soil moisture, small sample volumes, temperature disequilibria and possible chemical reactions in the lysometers prior to sampling. 

Appreciation is expressed to M.T. Osolnik, R.H. Postley, and the superintendent and staff of Mammoth Cave National Park for their assistance in the Mammoth Cave study, which was funded by the Office of Water Resources Research (now the Office of Water Research and Technology), U.S. Department of the Interior and to J. Tierney, park naturalist, and the staff of Carter Caves State Resort Park for their cooperation in the study of Cascade and X caves. 

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