The relationship between climate and hillslope form was investigated at 29 sites along two traverses: one from Berea, Kentucky, to Pioche, Nevada; the other from Glendive, Montana, to Ruidoso, New Mexico. A rigorous site-selection procedure was used to minimize the importance of nonclimatic factors and to ensure the inclusion of hillslopes in a variety of climatic regions.
Five hillslope variables were selected for comparison with nine climate variables. Each hillslope and climate variable has a theoretical or conceptual basis for use in this study.
The results support the hypothesis that hillslopes reflect regional climatic variations. Fifty-nine percent of the variation in the rate of curvature of the convex segment was explained by the climate variables. Forty-three percent of the variation in the slope of the straight segment was accounted for on the basis of climate. Thirty-seven percent of the variation in the slope of a regression line fitted through the entire profile was explained by variations in climate. Twenty-six percent of the variation in the slope length ratio was explained by the climate variables.
It was concluded that hillslopes in arid areas tend to be shorter, steeper, and have smaller radii of curvature of the convex segment than those in humid areas. Examination of the residuals from regression suggests that the site-selection procedure was successful in minimizing the geologic influence on hillslope form while in no way ignoring its importance. The statistical significance of the relationships indicates that there exists a state of quasi-equilibrium on the hillslopes. Lastly, evidence is provided for the existence of quantifiable relationships between geomorphological processes and hillslope forms. While this has been frequently asserted and is the basis of climatic geomorphology, it has rarely been tested.