SUMMARYA study of karst depression enlargement through time on the Western Highland Rim (physiographic province), based on two sets of aerial photography (1937, 1972) and field work, indicates that areal growth rates (dA/dt, mz/a) depend upon the surficial geologic setting. Areal growth rates were calculated from rates of long axis (dL/dt) and mean width (d W/df) enlargement assuming an elliptical plan shape. Areal growth rates averaged 40,70, and 100 m2/century for loessial, clayey residual, and silty colluvial surficial material, respectively.Estimates of average apparent age of karst depressions in each of the three surficial materials, based on linear growth rates, varied from 25,000 to 65,000 years B.P. An occurrence of mastodon (Mummut americanum) and ground sloth (Me&lonyx jeffersoni) from the Darks Mill depression as well as a pollen record from another depression dating from the Late Wisconsin glacial maximum in the same geomorphic setting yielded dates compatible with estimates of depression age.
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