Est. March 17, 1832
The Great Sand Dunes park, as well as the preserve, spread across a total of 233 sq. miles. The dunes themselves cover about 30 sq. miles and can reach a height of 750 ft. It is estimated that Lake Alamosa disappeared about 440,000 years ago, though the sand that remained was formed by smaller lakes later on. The predominant wind funnels toward three mountain passes; the Mosca, Medano, and Music Passes, creating and maintaining the dunes within this geological pocket.