Lake Michigan Coastal Dunes
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Winter Processes - Sand transport on frozen ground


On frozen ground, sand movement begins when strong winds put loose sand grains into motion (see pore-ice sublimation). Other grains are put into motion by the impacts of sand grains saltating over the cemented ground.

Saltating grains keep more of their kinetic energy when they travel over hard surfaces like frozen sand. (On loose sand, some of the energy is dispersed in the many small movements of grains during collisions with the surface.) Therefore, saltating grains can bounce higher and travel further on frozen ground than they can on loose sand.

Winter processes can transport sand further inland or over dune systems than sand movement during other seasons. One reason for this is that the saltating grains are travelling over frozen surfaces. Very strong winds, less resistance from vegetation, and snow/sand deposits smoothing out the topography are other reasons for longer transport distances.

 


Photo of loose sand deposits on frozen surface. (Hoffmaster State Park in December 2001.)


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Last updated 03/23/10.