CAVE GEOMORPHOLOGY AS INDICATORS OF PREFERENTIAL FLOWPATHS FOR CONTAMINANT TRANSPORT

Cave passage formation is commonly constrained to preexisting paths in a formation (joint planes, bedding surfaces, and the presence or absence of faults). Cave geomorphology (branchwork or network patterns) can differ from region to region based on the recharge mechanisms and the physical properties of the formations. As conduits act as preferential flowpaths for contaminant transport, characterization of the geomorphology of the cave passages in a region is important for developing an understanding of the pathways of contaminant transport in karstic aquifers. To assess the orientation of preferential flowpaths, the orientation of cave passages in the Salem and Springfield Plateaus and in the Perryville and Hannibal karst areas were determined. Analysis of the passage orientation and occurrence were plotted on Rosette Diagrams and compared with surface structures to determine if there was a structural control there as to the development. Eighty-six cave maps from fifteen counties have been analyzed. For most caves in the Springfield Plateau, the pattern of development is branchwork (a=0.05) with no preferential passage orientation. For most caves in the Salem Plateau, the pattern of development is rudimentary branchwork to branchwork (a=0.05) with no preferential passage orientation. Based on a more limited data set from the Perryville area, the pattern of development is Branchwork whereas the limited data set of the Hannibal area shows the pattern of development is network (a=0.05) with a preferential passage orientation of N20E. These initial observation of the cave geomorphologies for the Salem and Springfield Plateau and the Hannibal and Perryville karst areas suggest the distribution of caves within Missouri is not similar to that found by Palmer for cave passages world-wide. As understanding the cave geomorphology in a region provides insight about the orientation of preferential pathways along which groundwater flows, we find that in many areas of Missouri, prediction of preferential flowpath orientation will be difficult, as there appear to be few trends.