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The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)

Abstract


Journal of Sedimentary Petrology
Vol. 36 (1966)No. 3. (September), Pages 836-838

Heavy Mineral Concentration and Sastrugi-Like Deflation Furrows in a Beach Salcrete at Rockaway Point, New York: NOTES

Warren E. Yasso

ABSTRACT

Eolian deflation of marine beaches is sometimes affected by presence of a surface crust of salt-cemented sand which is here called a salcrete. Rapid and complete drying of saturated beach sand results in salcrete formation. A salcrete, up to a few millimeters in thickness, that had formed along the berm on Rockaway Point Beach Long Island, New York, was eroded subsequently by sand-laden wind from the backshore. Local removal of the salcrete allowed growth of sastrugi-like deflation furrows up to about one meter long and one-half meter wide. Locus of maximum deflation was the berm crest which represented the largest obstruction to wind flow across the beach. The deflation furrows were rimmed by a scarp about 1 cm high but under ideal conditions the scarp would be absent from upwind sid of the furrow. Coarse particles banked up against the downwind scarp would reveal wind direction even if the scarp completely rimmed the furrow.

Half-oval shaped heavy-mineral borders up to a few centimeters wide were observed around sand mounds deposited on the salcrete to the lee of shells. Apparently of streamline-flow origin, these borders were especially striking because of the relative scarcity of heavy minerals in sands of Long Island barrier beaches.

Because deflation furrows and heavy-mineral borders are excellent indicators of wind direction and velocity, a greater knowledge of their present-day occurrence might be of great value in paleo-wind studies of fossil beaches showing analogous forms.


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