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Gravel dispersion on a granite pediment (East Mojave Desert, California): a short‐term look at erosional processes
Author(s) -
EdingerMarshall S. B.,
Lund L. J.
Publication year - 1999
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/(sici)1096-9837(199904)24:4<349::aid-esp971>3.0.co;2-o
Subject(s) - geology , geomorphology , erosion , dispersion (optics) , hydrology (agriculture) , terrace (agriculture) , geochemistry , geotechnical engineering , archaeology , geography , physics , optics
Abstract Hypotheses about the influence of surface shape, landscape unit and vegetation cover on gravel dispersion were tested on a shallowly dissected portion of a low‐sloping granite pediment in the East Mojave Desert of California. Painted gravels (2 to 20 mm diameter) were placed at 117 nodes on a 6m × 3m grid. Gravel movements were recorded after 9.7 cm of precipitation over a four‐month period. Vectors indicating the magnitude and direction of gravel movement were longest for summits (24 cm, 34 nodes observed) and shortest for backslopes (14 cm, 27 nodes observed). Gravels beneath shrub canopies were protected significantly from rainsplash transport. To describe dispersion symmetry, eccentricity values were calculated using a ratio of variances of major and minor axes of an ellipse. Mean eccentricity values ranged from about 3 to 250 with dispersion on summits being the most symmetrical and dispersion in washes being the most elongated. Erosion is the most important soil‐ and pediment‐modifying process at upper elevations of the Granite Cove Pediment which is cut off from sediment additions because of washes incised at the base of the mountain front. Copyright © 1999 John Wiley & Sons, Ltd.