South-Central Region
Great Sand Dunes National Park And Preserve, Alamosa, CO

The Great Sand Dunes are the tallest sand dunes in North America, and a visit there is an amazing experience.

The Sand Dunes are in the far northern area of the San Luis Valley, a long, broad alpine valley in the Rocky Mountains of Colorado. The sand dunes form because winds flowing east across the valley carry sand and small rocks, then drop that debris when the winds slow as they hit the Sangre De Cristos mountains on the east side of the valley.

At the same time, small creeks (especially Medano Creek) provide water. The sand wicks moisture up from the creek, which keeps the sand from blowing away.

The result: sand dunes 750 feet (230 meters) tall. Hikers on the dunes frequently experience the dune-building process, being pelted by falling sand and rocks.

If the water were to dry up, the dunes would disappear. Instead, the Clinton administration turned this National Monument into a National Park in 2000 to protect the water sources, which local Colorado cities wanted to use for city water supplies.

A very unusual feature happens in Medano Creek, on the east edge of the dunes by the Visitor Center.

As sand falls and lands in the creek, underwater dunes build up and collapse, acting as natural underwater dams. This results in waves in the creek, much like ocean sea-shore waves, from intervals of every few seconds to a minute or more.

This is called stream-surge, and it?s considered very unique among geologists.

So Colorado has a creek that acts like the ocean. The sand in Medano Creek is good for building sand castles, and visitors with children seem to like playing in the creek as much as they like hiking the sand dunes.

The sand dunes are extremely popular among photographers, as the interplay between sunlight and shadows is visually stunning in the morning and at night. Skiers bring up old cross-country skis for summer conditioning, and the Park & Preserve contains much more than just the dunes?the park also has mountain hiking trails, alpine meadowland, and aspen groves at high altitude.

There is one campground, which is first-come, first served, it has 88 sites with a maximum of 6 people per site, and 3 group sites which require reservations (these are reserved quickly on January 1 each year). Camping fees are $12 per night in the individual units, and $3 per person per night in the group sites. Offroad camping is permitted in parts of the Preserve, but not close to the dunes.