Title page for ETD etd-07012010-165710


Type of Document Dissertation
Author Tranel, Lisa Marie
Author's Email Address lmtranel@vt.edu
URN etd-07012010-165710
Title Evaluation of Coupled Erosional Processes and Landscape Evolution in the Teton Range, Wyoming
Degree PhD
Department Geosciences
Advisory Committee
Advisor Name Title
Spotila, James A. Committee Chair
Eriksson, Kenneth A. Committee Member
Hole, John A. Committee Member
Kraal, Erin R. Committee Member
Law, Richard D. Committee Member
Keywords
  • Teton Range
  • landscape evolution
  • detrital apatite (U-Th)/He thermochronology
  • erosion
  • rock mass strength
  • cosmogenic radionuclides
Date of Defense 2010-06-17
Availability restricted
Abstract
The evolution of mountain landscapes is controlled by complex interactions between large-scale tectonic, surficial and climate conditions. Dominant processes are attributed to creating characteristic features of the landscape, but topographic features are the cumulative result of coupled surficial processes, each locally effective in a different climate or elevation regime. The focus of erosion by glacial, fluvial, or mass wasting processes is highly sensitive to small changes in boundary conditions, therefore spatial and temporal variability can be high when observed over short time scales. This work evaluated methods for dissecting the history of complex alpine landscapes to understand the role of individual processes influenced by changing climate and underlying bedrock. It also investigated how individual and combined mechanisms of surficial processes influenced the evolution of topography in the Teton Range in Wyoming. Detrital apatite (U-Th)/He thermochronology and cosmogenic radionuclide erosion rates were applied to determine spatial and temporal variability of erosion in the central catchments of the range. Spatial variability existed between the glacial and fluvial systems, indicating that sediment erosion and deposition by these processes was controlled by short-term variability in climate conditions. Effective glacial incision also controlled other processes, specifically enhancing rock fall activity and inhibiting fluvial incision. Short-term erosion rates were highly variable and were controlled by stochastic processes, particularly hillslope failures in response to slope oversteepening due to glacial incision and orientation and spacing of bedrock fractures. Erosion rates averaged over 10 ky time scales were comparable to long-term exhumation rates measured in the Teton Range. The similarity of spatial erosion patterns to predicted uniform erosion and the balance between intermediate and long-term erosion rates suggests the landscape of the Teton Range is approaching steady-state, but frequent stochastic processes, short-term erosional variability and coupled processes maintain rugged topographic relief.
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