Publication Date

Fall 2016

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

Advisor

Emmanuel J. Gabet

Keywords

Geomorphometry, Glacial geomorphology, Sierra Nevada

Subject Areas

Geomorphology; Geology; Geographic information science and geodesy

Abstract

This study employed a semi-automated approach to evaluate the degree of glacial modification of bedrock valleys in the Sierra Nevada, California, by quantifying morphological variability in cross-sectional form assessed from ~27,000 locations throughout the range. Measures of morphology including a shape ratio, a quadratic curve fit, and a power law curve fit were computed for each cross-section along with a novel metric, the V–index, and were compared to mapped glacial extent and bedrock lithology. Results indicate that Quaternary glaciations had a significant effect on bedrock valley morphology that is locally variable and largely independent of lithology at the range scale. Analysis of valley cross-sections and longitudinal profiles further suggest that glaciers in the Sierra Nevada modified pre-existing fluvial valleys primarily through widening. Moreover, the novel V-index is proposed as an alternative to traditional morphological measures due to its utility in describing irregular valley cross-sections and equivalent discriminatory power compared to established techniques for quantifying glacial geomorphology.

Available for download on Saturday, February 09, 2019

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