United States Border Patrol at Algodones Sand Dunes, California, USA. The fence on the US-Mexican border is a special construction of narrow, 15 feet tall elements, that are movable vertically. This way they can be lifted on top of the ever shifting sand dunes.
US Border Patrol
Department of Homeland Security, United States Border Patrol <a rel="nofollow" class="external free" href="http://www.dhs.gov/xlibrary/photos/sand-dune-fence.jpg">http://www.dhs.gov/xlibrary/photos/sand-dune-fence.jpg</a>