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Great Sand Dunes National Park and Preserve
The Great Sand Dunes National Park and Preserve became a United States National Park by an act of Congress on September 13, 2004. It is in the southern part of Colorado. The park contains approximately 85,000 acres (343 km²). 249,923 thousand people visited the park in 2003. The Sand Dunes are up to 750 feet high.
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Click on the thumbnails to enlarge the pictures. |
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This is the view from Highway 150 close to the entrance of Great Sand Dunes National Park. |
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You can see a lot of different wildlife. This photo was take right after entering the park. |
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Right after leaving the parking lot you experience this view. It is a long way to the top. |
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Two hikers appear to be very small on top of a dune. |
Natural History
The sand dunes rise close to about 750 feet (230 m) from the floor of the San Luis Valley on the western base of the Sangre de Cristo Mountains, covering about 19,000 acres (78 km²). They are the tallest sand dunes in North America. Anyone who visits the dunes has to wonder, "Where did such a bizarre feature come from? Why here?" They trace to perhaps 12,000 years ago.
The dunes were formed from sand deposits of the Rio Grande River and its tributaries, flowing through the San Luis Valley. Over the ages, westerly winds have picked up sand particles as they flew over the Rocky Mountains from the river flood plain. As the wind lost power before crossing the Sangre de Cristo Mountains, the sand was deposited on the east edge of the valley. This continues, and the dunes are slowly enlarging by the wind that daily changes the shape of the dunes. There are areas of black sand which are deposits of magnetite, a crystalline black oxide of iron.
The sand dunes form because as the wind blows sand and small rocks across the valley and up against Colorado's Sangre de Cristo Mountains, the wind slows and drops the debris. There are several streams flowing on the perimeter of the dunes. The streams erode the edge of the dune field, and sand is carried downstream. The water disappears into the ground, depositing sand on the surface. Winds pick up the deposits of sand, and blow them up onto the dune field once again.
Digging a few inches into the dunes even at 750 feet (230 meters) above the valley floor reveals wet sand. If the streams were to dry up, the dunes would disappear; in fact part of the motivation of turning the Monument into a Park in 2000 was the extra protection of the water, which Colorado's cities and agriculture covet.
It's very easy to experience the dune-building process. This is a very windy region, as hikers on the Sand Dunes will attest, as on many days they will be pelted by sand and even small rocks when hiking on the dunes. The wind carries sand and rocks from many tens of miles away.
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The wind produces wonderful textures in the sand. |
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Here you are looking at some of the surrounding mountains. |
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It is hard to believe but there are plants .. |
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.. and animals surviving in the sand dunes. |
Other Features
The park also contains alpine lakes and tundra, six peaks over 13,000 feet in elevation, ancient spruce and pine forests, large stands of aspen and cottonwood, grasslands, and wetlands — all habitat for diverse wildlife and plant species.
One of the most unusual features of the park happens at Medano Creek, which borders the east side of the Dunes and is located next to the Visitor Center and Bookstore. Because fresh sand continually falls in the creek, Medano Creek never finds a permanent and stable streambed. Small under-water sand dunes that act like dams continually form, and break down. So waders in the stream see surges--which look like waves--of water flowing downstream at intervals of just a few seconds to a minute or more. In a high-water year, these surges can be as much as a foot in height, so Colorado has a stream with something that resembles ocean waves. The creek also has great sand for building sand-castles, and visitors take advantage of that. Based on visitor activity, the creek is almost as popular as the dunes themseles. |
Access
Getting to the dunes requires walking across the wide and shallow Medano Creek, which only flows spring to early summer. Many run up the dunes, simply for the fun of rolling down again. Some ski the dunes. Hiking is permitted, with the warning that the sand can get hot in the summer, up to 140 Fahrenheit (~60 Celsius). The area gets snow in the winter. Some go on pack trips with horses. The closest city is Alamosa, Colorado, though Pueblo, Colorado Springs, Denver and Albuquerque, New Mexico are not far off.
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Hiking on the Great Sand Dunes is a lot of fun. The sand will get anywhere though! |
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The wind on top of the dunes always is very strong. It is a good idea to take a jacket with you. |
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Here you are on the highest sand dune and are looking back towards the starting point. The parking lot is in the upper right corner of the photo. |
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Once you reached the top of one of the higher sand dunes you have an amazing view towards the center of the dunes. |
Park History
The dunes and surrounding area were designated a National Monument in 1932. On November 22, 2000, United States President Bill Clinton signed the Great Sand Dunes National Park and Preserve Act of 2000, aiming at ultimate national park status, after more land was acquired. Great Sand Dunes National Park and Preserve became a United States National Park by an act of Congress on September 13, 2004.
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