Abstract

Eighteen samples of beach sand were collected at half-mile intervals along the shore of Cedar Point spit and connected mainland near Sandusky, Ohio. The samples were screened and treated with acid and the per cent of sand and carbonate in each size-grade was computed. A marked decrease in size-grade of the sand from the mainland beach to the far end of the spit is shown by the shifting of the maximum grade towards the finer sizes and by a decrease in both the median size and the equivalent grade. There is no appreciable increase in degree of sorting in the same direction as indicated by the grading factors determined from the cumulative curves. Secondary maxima of the samples on the beach near the mainland or on the mainland beach appear to be due to loading of the samples with material from nearby wave-cut cliffs or to the inclusion of lag concentrates in the sampling. The carbonate at first decreases and then increases through the series. In the individual samples it is found to make a larger proportion of the coarse and fine grades than of the intermediate grades. No satisfactory explanation of the latter relationship is known to the writers. The decrease in size-grade is not due to abrasion to any important extent but either to a selective sorting by the littoral currents or to some factor in the environment, such as the subaqueous slope, that changes progressively from place to place along the beach.

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