The relationship between lithology and slope morphology in the Tucson mountains, Arizona

Abstract

The relationship between lithology and slope morphology is investigated at eight sites on granitic, andesitic, and sedimentary hillslopes in the Tucson Mountains, Arizona. Several methods are used in the study. Topographic profiles are constructed. Skewness indices, slope length, and mean slope angles of the different slope profiles are computed and compared with each other. Debris size analysis has permitted for some profiles, the determination of hillfront/piedmont junctions. The nature and structural characteristics of the bedrock are the ones that determine the hillslope morphology in this semi-arid region. There are, as a matter of fact, variations in profiles on the same bedrock nature but differently exposed. More precise morphologic studies have been also done in comparing the different lithologic pairs. They have permitted to show some similarities in shapes. The granitic-andesitic slopes and andesiic-sedimentary slopes are the best comparisons which show the relationship between lithology and slope morphology. The granitic-sedimentary slope relationship is shown in the hillfront concavities, mountain front and piedmont mean slope angles.