climate does not provide enough precipitation to recharge the aquifer at the rate at which water is being withdrawn. The highest range within the park is the Panamint Range, with Telescope Peak being its highest point at . The Death Valley region is a transitional zone in the northernmost part of the Mojave Desert and consists of five mountain ranges removed from the Pacific Ocean. Three of these are significant barriers: the Sierra Nevada, the Argus Range, and the Panamint Range. Air masses tend to lose moisture as they are forced up over mountain ranges, in what climatologists call a rainshadow effect. The exaggerated rain shadow effect for the Death Valley area makes it North America's driest spot, receiving about of rainfall annually at Badwater, and some years fail to register any measurable rainfall. Annual average precipitation varies from overall below sea level to over in the higher mountains that surround the valley. When rain does arrive it often does so in intense storms that cause flash floods which remodel the landscape and sometimes create very shallow ephemeral lakes. The hot, dry climate makes it difficult for soil to form. Mass wasting, the down-slope movement of loose rock, is therefore the dominant erosive force in mountainous areas, resulting in "skeletonized" ranges (mountains with very little soil on them). Sand dunes in the park, while famous, are not nearly as widespread as their fame or the dryness of the area may suggest. The Mesquite Flat dune field is the most easily accessible from the paved road just east of Stovepipe Wells in the north-central part of the valley and is primarily made of quartz sand. Another dune field is just to the north but is instead mostly composed of travertine sand. The highest dunes in the park, and some of the highest in North America, are located in the Eureka Valley about to the north of Stovepipe Wells, while the Panamint Valley dunes and the Saline Valley dunes are located west and northwest of the town, respectively. The Ibex dune field is near the seldom-visited Ibex Hill in the southernmost part of the park, just south of the Saratoga Springs marshland. All the latter four dune fields are accessible only via unpaved roads. Prevailing winds in the winter come from the north, and prevailing winds in the summer come from the south. Thus, the overall position of the dune fields remains