Thin sand sheets with downstream foresets form in very shallow depths in the Platte River and resemble small sand waves. They produce internal horizontal stratification which is superficially similar to upper flow regime plane bed deposits except that the grains are differentiated into alternating coarse and fine laminations by sorting processes at the foreset. A 12-inch bed comprised of horizontal laminae examined in a river bank is believed to have formed by accretion of low amplitude sand waves on a floodplain during slowly increasing flood stages.

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