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Swash mark and grain flow

March 1, 1981

Swash marks composed entirely of coarse sand are commonly found on coarse-sand beaches. These swash marks are 10 to 30 centimeters in width and a few millimeters to one centimeter in height. Previous observations, mostly on finer-sand beaches, indicate swash marks are seldom over a few millimeters in height and are commonly composed of material readily floated by surface tension (e.g., mica flakes and shell fragments). Swash marks composed of coarse sand have both fining seaward and fining with depth trends in grain size. Apparently, the leading margin of a wave upwash drives a highly concentrated flow of grains in which both grain size and grain velocity decrease with depth. Therefore, large grains are transported at greater velocities than are smaller grains. Thus, at the maximum advance of an upwash, a swash mark is deposited which has the observed fining seaward and fining with depth trends in grain size.

Publication Year 1981
Title Swash mark and grain flow
DOI 10.1306/212F7C61-2B24-11D7-8648000102C1865D
Authors Asbury H. Sallenger,
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Sedimentary Petrology
Index ID 70011991
Record Source USGS Publications Warehouse
USGS Organization Coastal and Marine Geology Program