Death Valley 20: Dune and Mountain 1

Image Commentary

This image juxtaposes in one image three totally different landforms, each representing different cycles of erosion and depostion. The mountains in the background are steep and incredibly rugged. When it rains hard here, the torrents of high energy floodwater carry massive loads of very coarsely mixed sediment. The break of slope at the base of the mountains is the head of a large alluvial fan (across which, a road can be seen crossing right of center) where the flood debris gets dumped as soon as the waters carrying it looses its energy. Later on, the wind picks up the finest sandy sediment and transports it about a foot or so above ground until it reaches a point where the wind also looses its energy. At that point it also drops the sandy sediment. If the wind patterns follow a pattern as a result of the terrain, then dump sites occur and large accumulations of sand can develop. The Tucki Dunes in Death Valley are a fine example of such a dump site.