Campus Units
Geological and Atmospheric Sciences
Document Type
Article
Publication Version
Published Version
Publication Date
11-2014
Journal or Book Title
GSA Today
Volume
24
Issue
11
First Page
4
Last Page
10
DOI
10.1130/GSATG203A.1
Abstract
Tuolumne Meadows, in Yosemite National Park (USA), is a large sub-alpine meadow in the Sierra Nevada Mountains. Immediately adjacent to Tuolumne Meadows—and underlain by the same bedrock lithology (Cathedral Peak Granodiorite)—are vertical rock faces that provide exceptional opportunities to climbers. While the presence of a broad meadow suggests bedrock erodibility, the vertical rock walls indicate bedrock durability. We propose that the Tuolumne Meadows’s landscape is the result of variable glacial erosion due to the presence or absence of pre-existing bedrock fractures. The meadows and valleys formed because of concentrated tabular fracture clusters—a distinctive and locally pervasive type of fracturing—that were particularly susceptible to glacial erosion. In contrast, the vertical rock walls consist of sparsely fractured bedrock that was originally bounded by zones of pervasive tabular fracture clusters. Glacial erosion preferentially removed the highly fractured rock, forming prominent ridges in the upland surrounding Tuolumne Meadows. The orientation and spacing of the tabular fracture clusters, relative to ice flow, has exerted a fundamental control on the geomorphology of the area. The erosional variability exhibited by a single lithology indicates that the degree of fracturing can be more important than the host lithology in controlling landscape evolution.
Rights
Creative Commons Attribution license.
Copyright Owner
Geological Society of America
Copyright Date
2014
Language
en
File Format
app
Recommended Citation
Becker, Richard A.; Tikoff, Basil; Riley, Paul R.; and Iverson, Neal R., "Preexisting fractures and the formation of an iconic American landscape: Tuolumne Meadows, Yosemite National Park, USA" (2014). Geological and Atmospheric Sciences Publications. 151.
https://lib.dr.iastate.edu/ge_at_pubs/151
Comments
This article is from GSA Today 24 (2014): 4, doi:10.1130/GSATG203A.1. Posted with permission.