Great Sand Dunes National Park and Preserve

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The author at the park entrance, with the dune field and Sangre de Cristo Mountains in the background. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

Nestled against the western slopes of the Sangre de Cristo Mountains of south-central Colorado are the tallest sand dunes in North America. Covering 30 square miles and rising to 750 feet in height, the dunes are the centerpiece in a collection of diverse ecosystems. In 1932 the dunes and the surrounding areas were protected as Great Sand Dunes National Monument, but in 2004 the area was redesignated by Congress as Great Sand Dunes National Park and Preserve.

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Dune field against the Sangre de Cristo Mountains. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

The dunes themselves have been growing and shifting for hundreds of thousands of years. In that time sand from the floor of the San Luis Valley has been carried eastward by the prevailing winds. As sand-laden wind reached the Sangre de Cristo Mountains and slowed it dropped the sand in this natural trap. Over the millennia the sand accumulated here, continuously building dunes that migrated toward the mountains.

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Dune field against the Sangre de Cristo Mountains. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

Today enough vegetation has established itself in the valley to make the dunes relatively stable. Little new sand is added to the dune field, but within the field individual dunes continue to shift and migrate.

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Dune field against the San Luis Valley. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

My wife and I visited this park for about six hours last week. While we were there most people were gathered around the dunes themselves, eager to climb up the impressive mountains of sand. In spite of the name this park is more than just “great sand dunes,” however, and we were eager to see what else could be found here. In addition to the dunes this park encompasses rivers, grasslands, shrublands, wetlands, montane and subalpine forests, and alpine tundra. We were able to visit several of these diverse ecosystems in our limited time.

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Visitors hiking up the gigantic sand dunes. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

Throughout much of the year Medano Creek runs down from the mountains along the eastern edge of the dune field. In mid-summer, however, water was completely absent from the creek bed:

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A dry Medano Creek against the dune field and Sangre de Cristo Mountains. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

In spite of the dry creek, moisture-loving plants could be found along the banks. Most noticeable were the sandbar willows (Salix exigua, Salicaceae) and narrowleaf cottonwoods (Populus angustifolia, Salicaceae):

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Sandbar willows and narrowleaf cottonwoods along a dry Medano Creek. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

Other shrubs, herbs, and wildflowers also decorated the areas around the dunes:

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Foliage surrounding the dune field. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

In particular the bright, light purple flowers of Rocky Mountain beeplants (Cleome serrulata, Capparaceae) added swaths of color the the landscape:

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Rocky Mountain beeplant photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

This metallic wood-boring beetle (Coleoptera: Buprestidae) paid us a visit along the way. I suspect the local willows or cottonwoods may have been this insect’s host plant:

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Metallic wood-boring beetle photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

After my wife went to take a nap I decided to hike up the Mosca Pass Trail. This rocky 3.5 mile path gains about 1400 feet on its way up the Sangre de Cristo Mountains. It was once a popular route for Native Americans and pioneers to enter and exit the San Luis Valley.

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View heading up the Mosca Pass Trail. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

Early on some trees like these quaking aspen (Populus tremuloides, Salicaceae) provided a bit of shade:

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Quaking aspen photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

Before long the trees began to thin out, giving way to some sun-loving herbaceous plants like this scarlet gilia (Ipomopsis aggregata, Polemoniaceae)…

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Scarlet gilia photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

…Wyoming Indian paintbrush (Castilleja linariifolia, Scrophulariaceae)…

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Wyoming Indian paintbrush photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

…threetooth ragwort (Packera tridenticulata, Asteraceae)…

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Threetooth ragwort photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

…narrowleaf yucca (Yucca glauca, Asparagaceae)…

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Narrowleaf yucca photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

…and prickly pear cactus (Opuntia sp., Cactaceae):

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Prickly pear cactus photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

The views back down toward the San Luis Valley got more and more impressive with altitude:

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View down on the San Luis Valley from the Sangre de Cristo Mountains. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

In some places rocky outcrops on the trail provided opportunities to look back down on the dune field:

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View down on the dune field from the Sangre de Cristo Mountains. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

While the namesake dunes of Great Sand Dunes are certainly an impressive sight to behold, there is much more to this park to be discovered. We got a decent look at the diversity on our brief visit, but with many more miles of trails and different ecosystems to explore, a longer visit would certainly be welcome.

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Dune field against the Sangre de Cristo Mountains. Photographed 08/03/2013 at Great Sand Dunes National Park and Preserve near Alamosa, Colorado.

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About Jeremy Sell

Science and nature nerd.
This entry was posted in Botany, Culture, Ecology, Entomology, Geology, National Parks, Weather and Climate and tagged , , , , , , , , , . Bookmark the permalink.

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