From: http://www.nps.gov/grsa/

Nestled in southern Colorado, North America's tallest dunes rise over 750 feet high against the rugged Sangre de Cristo Mountains. The wind shaped dunes glow beneath the rugged backdrop of the mountains.

This geologic wonderland, containing 30 square miles of dunes, became a national monument in 1932. With the passage of the Great Sand Dunes National Park and Preserve Act of 2000, resources now also include alpine lakes and tundra, six peaks over 13,000' in elevation, ancient spruce and pine forests, large stands of aspen and cottonwood, grasslands, and wetlands--all habitat for diverse wildlife and plant species.