ASPECT-RELATED DIFFERENCES IN BADLANDS SLOPE MORPHOLOGY∗

∗I gratefully acknowledge the personnel at Badlands National Park without whose continued cooperation this work would not be possible. I also extend sincere thanks to Dr. Anthony Young, University of East Anglia, who provided a copy of the computer program for his Best Units Analysis. Professor William L. Graf, Department of Geography, Arizona State University, offered helpful suggestions for improvement of the manuscript. I am also indebted to Professor Neil E. Salisbury, Department of Geography, University of Oklahoma, with whom many of the problems and ideas presented here were first discussed.

ABSTRACT

Comparative analyses of slope profiles developed on erosional residuals in the Big Badlands of South Dakota revealed marked differences in slope morphology between north-facing and south-facing slopes. The profiles of south-facing slopes were found to be consistently shorter and steeper and are generally rectilinear in appearance. Profiles of the flatter, north-facing slopes are more complex in composition and exhibit a tread-and-riser appearance in overview. The absence of stream channels paralleling the bases of the pedimented residuals and the nearly flat-lying mudstones on which they are developed preclude an explanation of morphological differences based either on preferential stream corrasion or structural controls. The observed differences in slope form most likely reflect differences in type and rate of weathering and erosion that result from aspect-induced topoclimatic differential. More intense fluvial erosion on north-facing slopes is evidenced by significantly greater rilling densities. Evidence of mass wasting, although present on both north- and south-facing slopes, suggest aspect-related differences in magnitude and frequency of occurrence.

Notes

∗I gratefully acknowledge the personnel at Badlands National Park without whose continued cooperation this work would not be possible. I also extend sincere thanks to Dr. Anthony Young, University of East Anglia, who provided a copy of the computer program for his Best Units Analysis. Professor William L. Graf, Department of Geography, Arizona State University, offered helpful suggestions for improvement of the manuscript. I am also indebted to Professor Neil E. Salisbury, Department of Geography, University of Oklahoma, with whom many of the problems and ideas presented here were first discussed.