Simulation modeling and statistical classification of escarpment planforms

Nearly horizontal sedimentary sequences are typically eroded into escarpments capped by resistant rock layers. These escarpments record in planform the spatial variation in erosional processes. Simulation models have been constructed of scarp development by three processes, scarp backwasting, fluvial erosion, and groundwater sapping, acting singly or in combination. Scarp backwasting produces planforms characterized by broad, shallow reentrants and sharply pointed headlands. Fluvial erosion creates dendritic, sharply terminated canyons which gradually widen downstream because of superimposed backwasting. Groundwater sapping produces weakly branched canyons of nearly constant width with generally rounded headwalls. A number of morphometric variables are measured on natural and simulated scarps as well as lava flows, glacially eroded mountain fronts, and eroded tabular igneous intrusions. A discriminant analysis is able to classify 478 of these planforms into 9 categories with 87% accuracy.