HR: 10:35h
AN: H41G-02    [PDF]
TI: Chemical Denudation, Hillslope Morphology, and Long Term Persistence of Unchanneled Valleys
AU: * Mudd, S M
EM: simon.m.mudd@vanderbilt.edu
AF: Department of Civil and Environmental Engineering, Vanderbilt University, VU Station B 351831 2301 Vanderbilt Place, Nashville, TN 37235-1831 United States
AU: Furbish, D J
EM: david.j.furbish@vanderbilt.edu
AF: Department of Geology, Vanderbilt University, VU Station B #351805 2301 Vanderbilt Place, Nashville, TN 37235-1805 United States
AB: Modern understanding of hillslope geomorphology is grounded in the use of a statement of mass conservation. A great deal of progress has been made recently in our understanding of the components that have traditionally been included in this mass balance, such as tectonic uplift, soil production, and sediment flux. An important component of the mass balance has been largely neglected in studies of hillslope form and process, however. This component is mass loss due to chemical weathering. We develop a general equation for conservation of mass on a hillslope that includes a term for chemical weathering. Under a set of simplifying assumptions we explore the effect of including this weathering component on the predicted form of steady-state hillslopes. It is shown that unlike hillslopes experiencing only diffusion-like mechanical sediment transport, hillslopes with both diffusion-like mechanical sediment transport and mass losses due to chemical weathering can have a convex-concave profile at steady state. A necessary condition for such steady-state profiles is that the chemical denudation rate must exceed the mechanical denudation rate over the hillslope. This result has far reaching implications for interpreting climate histories for terrains with unchanneled valleys. Previous research has shown that a retreat of the fluvial system due to a climate change can lead to unchanneled valleys as a transient landscape feature; the results of our research suggest that chemical weathering can also cause unchanneled valleys to persist as stable landscape features.
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 1886 Weathering (1625)
SC: Hydrology [H]
MN: 2003 Fall Meeting