How fast does rock varnish grow?

Abstract

Research Article| February 01, 2000 How fast does rock varnish grow? Tanzhuo Liu; Tanzhuo Liu 1Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA Search for other works by this author on: GSW Google Scholar Wallace S. Broecker Wallace S. Broecker 1Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA Search for other works by this author on: GSW Google Scholar Geology (2000) 28 (2): 183–186. https://doi.org/10.1130/0091-7613(2000)28<183:HFDRVG>2.0.CO;2 Article history received: 28 Jun 1999 rev-recd: 08 Oct 1999 accepted: 11 Nov 1999 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 Tanzhuo Liu, Wallace S. Broecker; How fast does rock varnish grow?. Geology 2000;; 28 (2): 183–186. doi: https://doi.org/10.1130/0091-7613(2000)28<183:HFDRVG>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 SocietyGeology Search Advanced Search Abstract Rates of rock-varnish accumulation have never been systematically documented owing to the difficulty in accurately determining both varnish thickness and age. In this study, we quantitatively assess varnish-accumulation rates through thin sectioning and microscopic examination of rock varnish from radiometrically dated geomorphic features of late Quaternary age in the western United States drylands. Our data indicate that rock varnish grows at rates ranging from <1 to 40 µm/k.y. on subaerially exposed rock surfaces and rarely reaches a thickness exceeding 200 µm regardless of age. Our data also indicate that varnish-accumulation rates vary greatly from sample to sample at a given site, suggesting that varnish thickness does not correlate with the age of the associated geomorphic feature, invalidating the potential use of varnish thickness as a relative age indicator in geomorphology and archaeology. Nevertheless, being the slowest known accumulating terrestrial sedimentary deposit, rock varnish constitutes a unique long-term microscale sedimentary archive of past environmental changes in deserts. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.