Abstract

A sediment dispersal model is constructed using parameters derived from beach and lake samples obtained from an area with a known point source and dispersal direction. Mean size and percent of fine-grained heavy minerals decrease whereas sorting and kurtosis values increase in direction of transport. Skewness, percentages of both "fines" and coarsegrained heavy minerals are less useful as indicators of transport direction. The model also provides for comparisons of sample population means and variances of adjacent beach and lake deposits. Most values are greater for the beach populations if compared with their corresponding subaqueous counterparts. If the beach and lake population means of an area are compared with those from its source area, mean size is larger, percentage of fine-grained heavies is greater, kurtosis is lower (beach only) and sorting is poorer in the source area. The model is compared with the entire American shoreline of Lake Ontario as well as four regions divided upon differences in the shoreline and nearshore features. They are the: Niagara (subaqueous delta, till cliffs), Rochester (subaqueous drumlins and sand sheets), Oswego (small sand patches, till cliffs), and Eastern shore (sand beaches, dunes, and a subaqueous sand sheet). The net sand transport has been eastward along the southern shore, then northward along the eastern shore. The sands of the Niagara delta have been reworking during transgression while those on the adjacent beaches were derived from shoreline tills. The sands in the Rochester area have moved shoreward, probably from the eroded subaqueous drumlins offshore. The eastern shore sands show no lakeward transportation but were derived from the Oswego region in the past. A diminishing supply of sand in the source areas will result in a diminutation of beaches unless a substantial lowering of the lake level takes place.

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