GREAT SAND DUNES NATIONAL MONUMENT

national monument in south-central Colorado, U.S. It is located at the eastern edge of the San Luis Valley and parallels for about 10 miles (16 km) the western base of the Sangre de Cristo Range, 25 miles (40 km) northeast of Alamosa. Established in 1932, the region (area 60 square miles [155 square km]) contains some of the highest piled inland sand dunes in the United States, with ever-changing crests that rise to 700 feet (215 m).