Theses and Dissertations Collection

Many important understandings of the dynamic coupling between climate tectonics and erosion are based on models of bedrock erosion. However, many questions concerning incision process and the bedrock resistance to incision remain unanswered. Mechanistic based models of erosion provide the best opportunity to model landscape evolution with the most nuanced approaches to consider the erosive energy of a stream and the properties of rock that govern the transfer of that energy into erosion. The purpose of this dissertation is to experimentally test specific mechanistic erosion equations and use fieldwork in bedrock channels of central Arizona to investigate the controls on resistance to erosion. In chapter one flume experiments of sediment transport show that adding non-planar topography to the channel floor generates heavy tail distributions of impact energies and causes the energy delivered to the bed to shift from a decreasing to an increasing relation with the shear stress of the flow. In chapter two the morphology of lithologically variant bedrock channels in central Arizona shows strong correlations with resistance factors to processes of erosion and suggests that channel slope is sensitive to the resistance to abrasion and the size of sediment in the channel while channel width is sensitive to the bedrock joint spacing and the size of sediment in the channel. Chapter three uses fieldwork to investigate the accumulation of damage in channel surfaces through sub-aerial weathering processes and sediment impacts to show that mineralogy and crystalline grain size play an important role the evolution rock erodibility in a natural setting.