Co-evolution of Rock Strength, Erosion, and Steep Topography by Kirk F. Townsend A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Earth and Environmental Sciences) in the University of Michigan 2021 Doctoral Committee: Professor Marin K. Clark, Chair Associate Professor Andrew D. Gronewold Associate Professor Eric A. Hetland Associate Professor Naomi E. Levin Professor Nathan A. Niemi