Grass in the dunes at Great Sand Dunes National Park, CO
About this photograph
- Creator
- Margery H. Freeman
- Date created
- April 1984
- Location
- Great Sand Dunes National Park, Colorado
- License
- This photograph copyright ©1984. All Rights Reserved
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Learn more
- Search LEARN NC for Colorado, dunes, Great Sand Dunes National Park, Lake Alamosa, mountains, national parks, rifting, San Luis Valley, sand, sand dunes, sand sheet, Sangre de Cristo Mountains, and uplifting.
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Grass in the dunes at Great Sand Dunes National Park, Colorado. The grass is feathery and gold and casts spidery shadows on the sand below.
The dunefield of the park covers thirty square miles in the San Luis Valley. It is home to the tallest dunes in North America; the highest, Star Dune, towers at 750 feet. The nearby Sangre de Cristo Mountains were formed by rifting and uplifting of a geologic plate that formerly lay beneath an ancient sea. The San Juan Mountains, on the opposite edge of the valley, were formed by volcanic activity. Sediments and water from both ranges flowed down into the valley, into what geologists have named Lake Alamosa. Most of the lake disappeared due to climate change over thousands of years, leaving an enormous sand sheet. The sand is constantly pushed back and forth by the predominant winds and storm winds; the opposing forces create the huge dunes that cover the park. Alpine tundra, forests, massive dunes, grasslands, and wetlands are all protected by the park.
