Proportions of Exposed Igneous, Metamorphic, and Sedimentary Rocks

Research Article| August 01, 1975 Proportions of Exposed Igneous, Metamorphic, and Sedimentary Rocks HARVEY BLATT; HARVEY BLATT 1School of Geology and Geophysics, University of Oklahoma, Norman, Oklahoma 73069 Search for other works by this author on: GSW Google Scholar RICHARD L. JONES RICHARD L. JONES 1School of Geology and Geophysics, University of Oklahoma, Norman, Oklahoma 73069 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1975) 86 (8): 1085–1088. https://doi.org/10.1130/0016-7606(1975)86<1085:POEIMA>2.0.CO;2 Article history first online: 01 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 HARVEY BLATT, RICHARD L. JONES; Proportions of Exposed Igneous, Metamorphic, and Sedimentary Rocks. GSA Bulletin 1975;; 86 (8): 1085–1088. doi: https://doi.org/10.1130/0016-7606(1975)86<1085:POEIMA>2.0.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 SocietyGSA Bulletin Search Advanced Search Abstract Of the rocks exposed on the Earth's surface, 66 percent (±3.5 percent) are sedimentary and 34 percent are crystalline, at the 95 percent confidence level. Extrusive igneous rocks average about one-fourth of all crystalline rock outcrops, with the highest percentages in Asia and South America. Less than 5 percent of all Precambrian rocks are mapped as sedimentary.The relationship between the geologic age of a sedimentary rock and its outcrop area is lognormal and is well described by a decay curve with a half-life of 130 × 106 yr. That is, one-half of all existing sedimentary rocks are younger than Jurassic. Such a short half-life indicates that the rate of sedimentary recycling must be very rapid. 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.