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Sand Dunes Can Move Across the Landscape
Sand dunes aren't permanently fixed structures.
Wind continuously lifts and pushes sand grains up one side of a dune. As sand accumulates near the crest, it can slide down the opposite side.
Over long periods, this repeated movement causes entire dunes to migrate, sometimes threatening roads, buildings, or other infrastructure.
A landscape that looks completely still can actually be slowly traveling.
© U.S. Geological Survey