Karst landforms and drainage basin evolution in the Obey River basin, north-central Tennessee, U.S.A.

Abstract

An extensive karst landscape is developed on the Mississippian limestones of the dissected western margin of the Cumberland Plateau. Surface streams rising on the clastic rocks of the Cumberland Plateau flow down the escarpment and sink along its slopes at the upper contact of the Bangor Limestone. Some surface channels are continuous across the karst of the lower slopes while others terminate in blind valleys as swallow holes. At the base of the escarpment is an upland surface of doline karst developed in the Monteagle and St. Louis limestones at an elevation of 300–330 m. It consists of 1–5 km 2 shallow blind valleys and uvala-like closed depressions along with many smaller dolines. The internal drainage from the dolines and from the sinking streams is perched on the impermeable Warsaw Formation and emerges as contact springs on the inner gorges of the rivers which have cut deep narrow valleys below the level of the upland surface. Tributary streams to the Wolf, Obey and Roaring rivers (tributaries of the Cumberland River in north-central Tennessee) were analysed by fitting their longitudinal profiles to exponential and logarithmic functions. Linear segments of semilogarithmic plots permitted extrapolating both active streams and underdrained stream channels through the doline karst. The presently active streams extrapolated through the karst emerge at grade with the present-day base-level streams. Underdrained segments of the tributary valleys extrapolate to the upland surface and suggest that dry karst valleys can be interpreted much like river terraces. The development of interior drainage appears to be a much faster process than is the adjustment of the surface drainage.