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Parabolic Dunes


(non-Flash version)

Much of the Great Sand Dunes sand sheet is covered with vegetation. If strong winds erode a section of the vegetated sand (commonly referred to as a blowout), a parabolic dune may form. Leeward motion occurs if sand from the blowout is deposited on the opposite slope of the parabolic dune. Vegetation holds the "arms" of the dune in place as the leeward "nose" of the dune migrates forward toward the main dune field. Parabolic dunes are common in the sand sheet southwest of the main dunefield.