Millennial scale denudation rates of the Santa Lucia Mountains, CA: Implications for landscape evolution in steep, high relief, coastal mountain ranges
Abstract/Contents
- Abstract
- We use a suite of topographic metrics and cosmogenic 10Be-derived catchment-averaged denudation rates from 18 watersheds to evaluate patterns of millennial-scale erosion of the Santa Lucia Mountains, and test the explanatory power of the power-law incision rule for this landscape. Though the Santa Lucias possess up to ~1500 m of relief, catchment-averaged denudation rates are predominantly low, generally ranging between ~90 m/Myr - 350 m/Myr, with a single drainage yielding a rate >450 m/Myr. We test two forms of the power-law incision rule, one incorporating multiple, lithologically dependent erodibilities and one containing a single erodibility term. In both cases, power-law exponents are varied between 0 - 2. Despite an apparently noisy relationship between denudation rate and normalized channel steepness index, statistical analyses indicate the power-law incision rule provides an improved fit relative to a model that does not relate erosion rate to channel steepness. However, tests comparing both model forms indicate no significant improvement in model fit when using unique erodibility and channel steepness terms for each rock type. Estimates of erodibility coefficients are consistently low, ~10-6 - 10-5 m0.2/yr for all rock types mapped in the region. These low erosivities provide an explanation for lower-than-anticipated denudation rates. Where range asymmetry is most pronounced, watershed divides are identified as mobile by the χ landscape morphometric, yet we resolve no cross-divide change in erosion rate. Conversely, divides predicted by χ to be close to an equilibrium configuration have markedly different erosion rates in adjoining basins. These conflicting data sets, considered in conjunction with geomorphic indicators of river capture, may suggest that divide migration occurs in abrupt, punctuated episodes, rather than by gradual migration of divides.
Description
| Type of resource | text |
|---|---|
| Date created | May 2017 |
Creators/Contributors
| Author | Young, Holly |
|---|---|
| Advisor | Hilley, George |
| Degree granting institution | Stanford University, Department of Geological Sciences |
Subjects
| Subject | Department of Geological Sciences |
|---|---|
| Subject | School of Earth Energy & Environmental Sciences |
| Subject | denudation |
| Subject | cosmogenic radionuclides |
| Subject | tectonic geomorphology |
| Genre | Thesis |
Bibliographic information
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- Use and reproduction
- Theses courtesy of Stanford University Libraries. If you have questions, please contact the Branner Earth Science Library & Map Collections at brannerlibrary@stanford.edu.
Preferred citation
- Preferred Citation
- Young, Holly. (2017). Millennial scale denudation rates of the Santa Lucia Mountains, CA: Implications for landscape evolution in steep, high relief, coastal mountain ranges. Stanford Digital Repository. Available at: http://purl.stanford.edu/tw393xz7376
Collection
Master's Theses, Doerr School of Sustainability
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- young.hh@gmail.com
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