Quantitative morphology of landforms in carbonate rock basins in the Appalachian Highlands

Abstract

Karst topography occurs in the Appalachian Highlands where carbonate rocks are exposed. The principal landforms are sinking streams, dolines, and caves. Landform measures were devised for the drainage features and for dolines and applied to 62 small basins between Pennsylvania and Alabama. Conventional measures included a relief factor, drainage factors, and size and shape factors. Karst measures included carbonate rock fractions, measures of doline development, and measures of internal drainage. Factor analysis showed that the 15 measures contained only five independent variables. Various stream length measures are related to the basin area in much the same way as streams in noncarbonate basins showing the fluviokarst character of the Appalachian basins. Sinking stream length, SINKL, relates to the area of the sinking stream catchment, AB, by SINKL = 2.29 AB 0.85 . Doline karst was measured by either the area of internal drainage into dolines, AD, or by the number of dolines, N, per unit area of carbonate rock. These measures are related by AD = 0.0136 N 1.17 . The frequency of occurrence of dolines falls off exponentially with depth independent of rock type or structural setting. Comparison of several measures of karst in relation to rock type shows smallest and fewest dolines in the Ordovician dolomites and an intermediate size and number in the Ordovician limestones. The largest and most numerous dolines occur in the flat-lying Mississippian limestones of the Appalachian Plateau. This result may be an expression of the more sluggish solution kinetics of dolomite compared to calcite.