Crescentic dunes on the inner continental shelf off northern California

Geology
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Abstract

Large crescentic dunes that resemble barchans have been discovered within elongate scour depressions on the northern California inner continental shelf by using side-scan sonar. These dunes appear to be migrating obliquely to the regional shelf gradient; a preferred offshore direction of transport is indicated by the extended southern wings of many dunes. The isolated dunes and the scour depressions that contain them are located seaward of sea-floor outcrops off rocky capes and sea stacks. Repeated side-scan sonar records spanning four years (1981–1985) indicate that the dunes and bounding sidewalls of the scour depressions were somewhat modified, but the overall alteration to the bottom morphology during this period was only moderate to undetectable. The apparent low height of the dunes is consistent with a low migration speed. Over longer time periods (decades), the seaward transport of fine to medium sand in the crescentic dunes is probably an important way by which sand escapes the shallow part of the continental shelf in this region and mixes with the muddy deposits of the central shelf.

Publication type Article
Publication Subtype Journal Article
Title Crescentic dunes on the inner continental shelf off northern California
Series title Geology
DOI 10.1130/0091-7613(1987)15<1134:CDOTIC>2.0.CO;2
Volume 15
Issue 12
Year Published 1987
Language English
Publisher Geological Society of America
Description 4 p.
First page 1134
Last page 1137
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