Stress relief fracturing provides the large mechanical apertures needed for the development of conduit porosity in carbonate aquifers. Examination of valleys incised into Mississippian age limestones throughout the Appalachian plateaus has demonstrated a consistent pattern taken in the development of conduits in these settings. Master conduit (caves) are found beneath the valley walls in general, not directly beneath the actual surface channel. Common features of the studied ''Cumberland style'' caves are valley-parallel master conduit segments, exceptional concordance of conduit orientation with minor surface topographic variations, development on distinct ''levels,'' and development in a downdip position from master surface streams. The recognition that these conduits form along geologically young fracture systems of increased aperture is a departure from previous theories of cave origin. Prior theories have either explicitly or implicitly assumed that caves develop along joints and fractures of significant geologic age, related more to regional tectonic forces than to present-day topographic influences. ¿ American Geophysical Union 1994