Bedrock fracture control of glacial erosion processes and rates

Abstract

Research Article| May 01, 2010 Bedrock fracture control of glacial erosion processes and rates Miriam Dühnforth; Miriam Dühnforth 1Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, Colorado 80303, USA Search for other works by this author on: GSW Google Scholar Robert S. Anderson; Robert S. Anderson 2Institute of Arctic and Alpine Research (INSTAAR) and the Department of Geological Sciences, University of Colorado, Boulder, Colorado 80303, USA Search for other works by this author on: GSW Google Scholar Dylan Ward; Dylan Ward 2Institute of Arctic and Alpine Research (INSTAAR) and the Department of Geological Sciences, University of Colorado, Boulder, Colorado 80303, USA Search for other works by this author on: GSW Google Scholar Greg M. Stock Greg M. Stock 3Yosemite National Park, Resources Management and Science, El Portal, California 95318, USA Search for other works by this author on: GSW Google Scholar Geology (2010) 38 (5): 423–426. https://doi.org/10.1130/G30576.1 Article history received: 30 Jul 2009 rev-recd: 25 Nov 2009 accepted: 02 Dec 2009 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Miriam Dühnforth, Robert S. Anderson, Dylan Ward, Greg M. Stock; Bedrock fracture control of glacial erosion processes and rates. Geology 2010;; 38 (5): 423–426. doi: https://doi.org/10.1130/G30576.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The importance of rock type and tectonic history on rates of glacial erosion, and the relative roles of glacial quarrying and abrasion, are poorly understood. We use concentrations of cosmogenic 10Be in glacial polish and measurements of bedrock fracture spacing to explore the relationship between erosion rates and rock fracturing at 23 sites along Tuolumne River valley and five sites in Tenaya Canyon in Yosemite National Park, California, USA. Most sites yield 10Be concentrations that can be best explained as reflecting solely postglacial nuclide accumulation. Six sites, however, display anomalously high concentrations, implying incomplete removal of the pre-glacial nuclide inventory during the last glaciation; these require that erosion in the last glacial cycle was <2–3 m. These low-erosion sites occur preferentially in massive units of the Cathedral Peak Granodiorite and the El Capitan Granite. Fractures in high-erosion sites are more closely spaced than in low-erosion sites, with spacings that average 1.1 ± 0.03 m and 3.3 ± 0.1 m, respectively. Our data suggest that the distance between fractures in the rock, dictated in part by the original spacing in a particular pluton, and in part by the specific tectonic history of the Sierra Nevada, governs the pace of glacial erosion in Yosemite. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.