The NSS Bulletin
- ISSN 1090-6924
Volume 52 Number 1: 57-69 - December 1990
A publication of the National Speleological Society
Lithologic Control of
Shallow Karst Groundwater Flow on the Sinkhole Plain of Kentucky
Ghristopher G. Groves and Nicholas Crawford
The Lost River Groundwater Basin in Warren County, Kentucky is a karst drainage system encompassing 143 kmē developed within the Mississippian St. Louis and Ste. Genevieve Limestones. Near the contact between these formations are two bedded chert units, the Lost River Chert within the Ste. Genevieve and The Corydon Chert Member of the St. Louis, which appear to be perching layers to shallow karst groundwater flow. Groundwater may be seen flowing at or near the tops of these beds in various cave streams and at swallets and springs within the basin.
In order to compare the vertical positions of these chert intervals to shallow karst groundwater flow, geologic structure maps of the Lost River Chert and the Corydon Chert Member were prepared for the basin. A contour map of the water table (at or near which shallow karst groundwater flow is assumed to take place) was constructed over the same area. These surfaces were digitized, then contoured and compared using SURFACE II and DISSPLA computer graphics systems. Correlation was accepted for points where the water table is either 6 m above or below the tops of the two chert layers. The water table (at baseflow conditions) was found to correlate with the Lost River Chert over 42.6% of the basin, as well as 40.7% for the Corydon Member. Shallow karst groundwater flow is found to correlate with bedded cherts over 83.3% of the study area, and therefore it is concluded that chert layers are concordant to shallow groundwater flow. This concordance, in conjunction with other observations of the relationship between groundwater flow and the cherts, suggests that the cherts strongly affect shallow karst groundwater flow within the Lost River Groundwater Basin.
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