Accession Number:

AD0736938

Title:

Study of Subaqueous and Subaerial Sand Ripples.

Descriptive Note:

Final rept. 1 Feb 67-31 Jan 72,

Corporate Author:

UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF GEOLOGICAL SCIENCES

Personal Author(s):

Report Date:

1972-01-15

Pagination or Media Count:

293.0

Abstract:

Sand ripples in the marine and desert environments were studied so that comparisons of ripple structure, geometry, movement and behavior could be made with theoretical studies. Crest sediment of small wavelength oscillation ripples is slightly coarser than the material in the troughs, whereas for megaripples, trough sediment is coarser. Ripple wavelength is a function of grain size. Sediment motion on the sea floor is negligible when the average surge velocity is less than 10 cmsec, particle motion commences at 18 to 21 cmsec and is widespread at 27 to 30 cmsec. Bedload exceeds 80 of the total load and 95 of all transport occurs within 15 cm of the bottom. In the aeolian environment ripple geometry is variable and wavelength is a function of crest grain size. Using tracer sand it was determined that under winds of 15-25 mph, threshold velocities range from 21 to 36 cmsec, average grain velocity is 0.78 mmin, natural ripples travel at 0.4 cmmin and the rate of sand transport is about 0.4 metric tonsmeter widthhour. Author

Subject Categories:

  • Geology, Geochemistry and Mineralogy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE