Death Valley National Park contains several dune fields. The most visited would be the Mesquite Dunes adjacent to Stovepipe Wells. Other popular dunes are the Eureka Dunes, Panamint Dunes, Saline Valley Dunes, and the Ibex Dunes. Please, refer to the Park map for locations. All these dunes are formed by the accumulation of loose sediment, namely sand-sized particles. The source of this sediment is from erosion of rock by water, wind, and gravity. There are a couple of requirements for dune formation. One of these requirements is wind. Sand is blown by wind until it reaches an obstacle. In the case of Death Valley, obstacles are mainly mountains! Wind doesn't have enough energy to blow the sand-sized particles up and over the mountains, as the wind-energy decreases they drop their load and deposit them where we see it today. It takes many wind storms to accumulate the amount of sand we see in Death Valley's dune fields. Although their movement is limited by prevailing wind directions and mountains, individual dunes are constantly changing shape and location. It not uncommon to find that footprints from a previous day's hike have been erased, cleaned by the wind. Along with wind, another requirement is a dry climate. Fortunately for our dunes, the average rainfall in Death Valley is only 1.65 inches per year. Moisture would cause sand-grained sized particles to stick together, making it much harder for wind to move the material.