Controls on Speleogenesis in the Upper-Mississippian Pennington Formation on the Western Cumberland Plateau Escarpment

Much of the pioneering work on caves of the Cumberland Plateau (province spanning Tennessee, Kentucky, Alabama, and Georgia) has been stratigraphically located within the Mississippian Bangor and Monteagle Limestones, wherein some of the region’s largest and most spectacular caves occur. Of interest to the understanding of this karst landscape, but severely underrepresented in the literature thereof, are caves and karst features in a heterogeneous sequence of clastics and carbonates known collectively as the Pennington Formation (Upper Mississippian). This work consisted of a regional study of Pennington caves on the western Cumberland Plateau escarpment (Alabama and Tennessee), and a case study of Pennington caves in Savage Gulf State Natural Area (Grundy County, Tennessee). The objective of this research was to determine controls on speleogenesis in the Pennington Formation, using cave geomorphology, dye tracing, and GIS to explore lithologic, hydrologic, and structural influences on karst processes. This resulted in a conceptual model for speleogenesis in the Pennington Formation, with the major controls being: 1) direct and diffuse recharge from the caprock, undersaturated with respect to calcite; 2) thin, horizontally bedded limestones sandwiched by shales and other insoluble rocks; and 3) networks of stress release fractures oriented parallel to major stream valleys. Our present understanding of the Cumberland Plateau could be advanced by further study of karst dynamics in the Pennington Formation