Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Geology Signup for GSW Email News
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Geology; February 2000; v. 28; no. 2; p. 183-186; DOI: 10.1130/0091-7613(2000)28<183:HFDRVG>2.0.CO;2
© 2000 Geological Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Liu, T.
Right arrow Articles by Broecker, W. S.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

How fast does rock varnish grow?

Tanzhuo Liu1 and Wallace S. Broecker1

1 Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA

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.

Key Words: rock varnish • thickness • growth rate • age control • microstratigraphy • western United States




This article has been cited by other articles:


Home page
 GeologyHome page
L. A.J. Garvie, D. M. Burt, and P. R. Buseck
Nanometer-scale complexity, growth, and diagenesis in desert varnish
Geology, March 1, 2008; 36(3): 215 - 218.
[Abstract] [Full Text] [PDF]

Home page
 GeologyHome page
J. Quade
Desert pavements and associated rock varnish in the Mojave Desert: How old can they be?
Geology, September 1, 2001; 29(9): 855 - 858.
[Abstract] [Full Text] [PDF]

Home page
 Progress in Physical GeographyHome page
D. J. Nash
Arid geomorphology
Progress in Physical Geography, September 1, 2000; 24(3): 425 - 443.
[PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Geological Society of America