December 05, 2008
This photo demonstrates the ability of sand dunes to walk, or migrate, as they gradually engulf stationary objects in their path. Towards the southern end of The Great Highway in San Francisco, California, the cables which once cordoned a walking path now plunge directly into a massive sand dune. Fortunately, the local humans have adapted, and you can see their recent tracks skirting the side of the dune. Dunes often migrate through the force of wind alone, but this particular incursion may have been water assisted as a result of storm waves during the winter months. Photo taken on May 30, 2008.