Reading the recorded history of soil mantled hillslopes

Abstract

Hillslope soils cover a large proportion of Earth’s terrestrial landscapes. This dissertation is a theoretical exploration of how chemical and mechanical processes affect the formation and dynamics of both hillslope soils and soil mantled landscapes. It explores how hillslopes adjust to time varying erosion rates. Statements of mass conservation for both the total soil layer and constitutive soil phases are derived that include terms describing both chemical and mechanical denudation. These statements are used to demonstrate that chemical processes are as important as mechanical processes in determining the morphology of landscapes, and that chemical properties of hillslope soils can be used to quantify chemical denudation rates. Analyses are performed for both the steady state case (where erosion rates do not change in time) and the transient case (where erosion rates are time-varying). Transient simulations show that hillslope soils respond to changes in channel incision over characteristic timescales, and changes in channel incision leave characteristic chemical and physical signatures on the landscape that last for tens of thousands to millions of years.