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Abstract

Calcarenites on San Salvador Island, Bahamas, preserve a history of ooids and skeletal grains reworked by wind. French Bay and Cockburn Town members of the Pleistocene Grotto Beach Formation and comparable Holocene strata contain eolian sandflow, grainfall, and wind-ripple structures and textures similar to those of siliciclastic eolian deposits. In thin section, well-cemented, closely packed, fine-grained strata correspond with ledges in outcrop; poorly cemented, loosely packed, medium-grained strata correspond with recesses. Wind-ripple strata form topsets, brinksets, and bottomsets. White, ledgy, fine-grained, basal laminae are overlain by gray, recessed, medium-grained laminae to form one wind-ripple stratum. Sandflow cross-strata are tabular in longitudinal sections, lenticular in transverse sections, and wedge out into grainfall and wind-ripple bottomsets. They coarsen upward from white, ledge-forming, fine-grained laminations to gray, recess-forming, medium-grained laminations. Grainfall forms weakly stratified, fine-grained, ledge-forming units of variable thickness and geometry. They are associated with sandflow cross-strata and thicken downslope as bottomsets, especially in cross-bed sets thinner than 2 m (7 ft). Grainfall strata are difficult to recognize where structural relations between foreset and bottomset beds are hidden.

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