Physical weathering in arid landscapes due to diurnal variation in the direction of solar heating

Abstract

Research Article| January 01, 2005 Physical weathering in arid landscapes due to diurnal variation in the direction of solar heating L.D. McFadden; L.D. McFadden 1Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131, USA Search for other works by this author on: GSW Google Scholar M.C. Eppes; M.C. Eppes 2Department of Geography and Earth Sciences, University of North Carolina at Charlotte, North Carolina 28223, USA Search for other works by this author on: GSW Google Scholar A.R. Gillespie; A.R. Gillespie 3Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar B. Hallet B. Hallet 3Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar Author and Article Information L.D. McFadden 1Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131, USA M.C. Eppes 2Department of Geography and Earth Sciences, University of North Carolina at Charlotte, North Carolina 28223, USA A.R. Gillespie 3Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA B. Hallet 3Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA Publisher: Geological Society of America Received: 17 Oct 2003 Revision Received: 29 Feb 2004 Accepted: 02 May 2004 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2005) 117 (1-2): 161–173. https://doi.org/10.1130/B25508.1 Article history Received: 17 Oct 2003 Revision Received: 29 Feb 2004 Accepted: 02 May 2004 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation L.D. McFadden, M.C. Eppes, A.R. Gillespie, B. Hallet; Physical weathering in arid landscapes due to diurnal variation in the direction of solar heating. GSA Bulletin 2005;; 117 (1-2): 161–173. doi: https://doi.org/10.1130/B25508.1 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 SocietyGSA Bulletin Search Advanced Search Abstract Despite the prominent role of physical weathering in arid and semi-arid landscapes, there has been little study of the specific processes responsible for the rapid breakdown of subaerially exposed rocks. For example, many boulders and cobbles in deserts exhibit fine near-vertical cracks. Although workers have hypothesized that these and other cracks are initiated by diurnal heating and cooling, no convincing specific mechanism for their formation has been proposed. We have characterized these cracks at eight sites on surfaces of different ages in the Mojave, Sonoran, and Chihuahuan Deserts, and the high desert of central New Mexico. Our data reveal four basic types of cracks: longitudinal, surface-parallel, fabric-related, and meridional. The orientations of the first three types are associated with clast shape and rock fabric. The azimuths of meridional cracks, however, are preferentially aligned north-south, typically with a nonrandom multimodal distribution. We propose that these cracks are caused by tensile stresses that arise in the interior of clasts due to strong radial gradients in temperature that evolve and rotate in alignment with the sun's rays. We suggest that the multimodal nature of crack orientations may be in part attributable to the seasonally varying, latitude-dependent solar elevation angle. Over millennial time scales, we suggest that this thermal cracking is an efficient weathering process that, together with cumulic soil epipedon development, creates the key attributes of most desert pavements. In addition to individual clasts exposed on desert surfaces, this mechanism of cracking is potentially significant in other climates and on other planets, as well as for rock outcrops and for man-made structures. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.