The NSS Bulletin - ISSN 1090-6924
Volume 56 Number 2: 96-103 - December 1994

A publication of the National Speleological Society

Comparison of Cave Passageways with Fracture Traces and Joints in the Black Hills Region of South Dakota
Tariq J. Cheema and M.R. Islam

Abstract

More than a dozen major caves, including Jewel Cave and Wind Cave, are present in the Madison Limestone of the Black Hills region of South Dakota. Collectively, the Black Hills caves consist of hundreds of kilometers of cave passageways. In general, cave passageways are believed to show more or less the same orientation as that of fracture traces and joints. Keeping in mind the complex geological processes and tectonic events involved in the formation of the Black Hills and its caves, the problem of correlating caves passageways with the fracture traces, lineaments, and joints becomes a challenging task. This analysis will help to understand the structural control involved in the creation and the development of the Black Hills caves. The study area hosts Crystal Cave and Black Hills Caverns and is flanked by Boxelder Creek to the north and Rapid Creek to the south, in the vicinity of Rapid City. Fracture trace and lineament mapping, done on aerial photographs and SPOT images, resulted in the creation of rose diagrams. Similarly, cave passageways for Crystal Cave and Black Hills Caverns were also plotted on a rose diagram. Joints were measured in the field and plotted on rosettes with 10° intervals. Because rose diagrams are good only for visual comparisons, a modified Kolmogorov-Smirnov (K-S) test was performed to statistically compare the rose diagrams. The results were then compared with other cave passageways in the Black Hills. The degree of correlation with cave passageways was found to be the highest for fracture traces, followed by a somewhat lower degree of correlation for lineaments, and no correlation for joints. The cave passageways, fracture traces, and lineaments showed north-eastern (NE) and north-western (NW) preferred orientations, NE being more prominent. The joints showed a strong NE trend in their orientation but did not pass the statistical test of correlation. The most likely reason is that fracture traces and lineaments represent not only underlying fractures but also solution cavities formed along bedding planes while fracture data do not include solution cavities. This observation is confirmed by a rose diagram of borehole fractures of the Madison Formation.

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