Dating precariously balanced rocks in seismically active parts of California and Nevada

Research Article| June 01, 1998 Dating precariously balanced rocks in seismically active parts of California and Nevada John W. Bell; John W. Bell 1Nevada Bureau of Mines and Geology, University of Nevada, Reno, Nevada 89557 Search for other works by this author on: GSW Google Scholar James N. Brune; James N. Brune 2Seismological Laboratory, University of Nevada, Reno, Nevada 89557 Search for other works by this author on: GSW Google Scholar Tanzhuo Liu; Tanzhuo Liu 3Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar Marek Zreda; Marek Zreda 4Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar James C. Yount James C. Yount 5Global Change and Climate History Team, U.S. Geological Survey, Reno, Nevada 89557 Search for other works by this author on: GSW Google Scholar Geology (1998) 26 (6): 495–498. https://doi.org/10.1130/0091-7613(1998)026<0495:DPBRIS>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation John W. Bell, James N. Brune, Tanzhuo Liu, Marek Zreda, James C. Yount; Dating precariously balanced rocks in seismically active parts of California and Nevada. Geology 1998;; 26 (6): 495–498. doi: https://doi.org/10.1130/0091-7613(1998)026<0495:DPBRIS>2.3.CO;2 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 Precariously balanced boulders that could be knocked down by strong earthquake ground motion are found in some seismically active areas of southern California and Nevada. In this study we used two independent surface-exposure dating techniques—rock-varnish microlamination and cosmogenic 36Cl dating methodologies—to estimate minimum- and maximum-limiting ages, respectively, of the precarious boulders and by inference the elapsed time since the sites were shaken down. The results of the exposure dating indicate that all of the precarious rocks are >10.5 ka and that some may be significantly older. At Victorville and Jacumba, California, these results show that the precarious rocks have not been knocked down for at least 10.5 k.y., a conclusion in apparent conflict with some commonly used probabilistic seismic hazard maps. At Yucca Mountain, Nevada, the ages of the precarious rocks are >10.5 to >27.0 ka, providing an independent measure of the minimum time elapsed since faulting occurred on the Solitario Canyon fault. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.