Which landform development mechanism explains the sorting of sediment grain sizes within an alluvial fan?

💡 Explanation

When sediment-laden flow experiences decreasing slope on an alluvial fan, shear stress declines downslope because gravitational potential converts to kinetic energy, causing coarser particles to deposit proximally and finer grains distally. Therefore shear stress decline explains sediment sorting, rather than creep, saltation reversal, or viscosity reduction which relate to different flow conditions.

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