National monument, south-central Colorado, U.S. At the eastern edge of the San Luis Valley, it parallels for about 10 mi (16 km) the western base of the Sangre de Cristo Range. Established in 1932, the 60-sq-mi (155-sq-km) region contains some of the highest inland sand dunes in the U.S., with changing crests that rise to 700 ft (215 m)
A sand dune is a hill of sand near the sea or in a sand desert. = dune. a hill formed of sand in a desert or near the sea. Hill, mound, or ridge of windblown sand or other loose material such as clay particles. Dunes are commonly associated with desert regions and seacoasts, and there are large areas of dunes in nonglacial parts of Antarctica
A hill or ridge of sand piled up by the wind commonly found along shores, along some river valleys, and generally where there is dry surface sand during some part of the year
A hill or ridge of aeolian sand deposits with a minimum height of less than one meter and a maximum height of about 50 meters Found in hot deserts and along sandy coastlines