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43622-AC8
How Does Sand Sort?

Jeffrey D. Parsons, University of Washington (Seattle)

In this effort, a number of small experiments were performed and compared to fine-scale stratigraphy in a variety of environments. Grain-size sorting is a complex process that is dependent on the Stokes number. The Stokes number is essentially the ratio of the relevant time scale associated with inertia of a particle with the time scale of fluid mechanical turbulence. Because turbulence is inherently intermittent in space and time, grain-size sorting occurs for finer particles than previous thought. These effects are retained in the geological record as the formation of highly complex fine-scale interbedded layers.

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