The development of granite landforms on the northern and western margins of the Santa Catalina Mountains, Arizona

Abstract

The scientific literature regarding the origin of granite landscapes is dominated climatic geomorphologists who argue that these landscapes are the products of deep weathering of highly jointed granite under tropical climates, or structural geomorphologists who insist that structure and lithology are of greater importance than climate. This study examines the origin of three distinct landscapes found on three granite pediments along the western and northern margins of the Santa Catalina Mountains of southeastern Arizona. The Oracle granite pediments are dominated by boulder inselbergs, those of the Catalina granite by domed inselbergs and platforms, while Wilderness Suite granite pediments are sloping shelves that lack these characteristic landforms. These granites have a similar late Cenozoic history of weathering and erosion, but differ in structure, lithology, and age. Field evidence and laboratory analysis support the arguments of structural geomorphologists and indicate that the model presented by climatic geomorphologists is not valid for the study area. The landforms found here appear to be the products of surface weathering and fluvial erosion guided by joints and lithology.