Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 63 Number 2: 67-75 - August 2001

A publication of the National Speleological Society

A simple map index of karstification and its relationship to sinkhole and cave distribution in Tennessee
Gregory A. Shofner, Hugh H. Mills and Jason E. Duke


We here introduce a readily determined index of surface karstification, termed “sinkhole” index, based on the mean spacing of closed contours in a given area. The index shows a high correlation with total sinkhole area and a moderate correlation with total volume. The index was measured in 5056 blocks with dimensions of 2.5’ of latitude by 2.5’ of longitude, covering much of Tennessee. A new map showing the distribution of this index in the state is similar to one previously published karst map of Tennessee, but shows the variation of karstification in a more detailed manner. The sinkhole index was also used to compare the distribution of sinkholes and caves in Tennessee, using cave data compiled by the Tennessee Cave Survey. Maps of the sinkhole index and the number and total length of caves in each 2.5’ x 2.5’ block show strong regional similarities. However, there are dramatic exceptions. In addition, using blocks as the basic unit of analysis, the correlation coefficients between the sinkhole index and the two measures of cave abundance are low, generally explaining less than 10% of the variance. Thus, although similar geologic conditions appear to favor both sinkhole development and cave formation, the actual processes involved in the development of these two types of features seem to be only weakly related.

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