Great Sand Dunes National Park

December 09, 2011

DunesAndPeople (2)

: Ingrid Wood  
Summary Author: Ingrid Wood; Jim Foster

The photo above shows the massive tan-colored dunes in Great Sand Dunes National Park and Preserve, Colorado. Hikers in the foreground give scale to the immense size of these windblown sand dunes, which reach up to about 750 ft (230 m) above the surrounding landscape -- perhaps the tallest in North America. These dunes cover some 39 sq mi (100 sq km) and over thousands of years have settled up against the windward flank of the Sangre de Cristo Mountains, pushed by prevailing southwest winds across the San Luis Valley. The source of the sand was a widespread sand sheet, sand left behind when ancient lakes dried up, in the central portion of the San Luis Valley. Photo taken on August 22, 2007.

Photo Details: Camera: Canon PowerShot A530; Focal Length: 9.8mm; Aperture: f/7.1; Exposure Time: 0.0031 s (1/320).