The dunes range in height from a few feet to more than 300 feet. Major periods of dune movement occurred 8,000 to 5,000 years ago, with more recent periods of lesser dune reactivation. In the most recent centuries, climatic conditions have been wet enough for the dunes to support sufficient vegetation to keep them stable. Nevertheless, dune soils are poorly developed because of the constant erosion and deposition of sand. Annual rainfall varies from 17 inches in the western Sandhills to 23 inches in the east.
Cattle ranching is the primary land use in the region.
Blowouts form in the dune tops when their protective vegetative cover is reduced and wind erosion eventually forms craters, depositing the excavated sand on the downwind side. Most blowouts are less than one acre in size. Eventually, blowouts can heal, reverting to Sandhills prairie. Limiting Factors Ecologists are not sure what caused the sudden decline in blowout penstemon in the first half of the 20th century, but several factors, including the Great Drought of the 1930s, might have contributed. Blowout penstemon requires abundant soil moisture, and in dry years, moisture is not adequate even in sparsely vegetated blowouts.