Great Sand Dunes National Park

Great Sand Dunes National Park

• Located in the eastern edge of the San Luis Valley, in southern Colorado.  This park features North America's tallest dunes, rising over 750 feet high against the rugged Sangre de Cristo Mountains.

• The dunes cover an area of about 30 sq mi (78 km2) and are estimated to contain over 1.2 cubic miles (5 billion cubic metres) of sand.

• After the lake in the valley disappeared, only sand was left, and the southwestern wind forced it to head to the mountains , eventually forming a huge field of sand over tens of thousands of years.

The four primary components of the Great Sand Dunes system are the mountain watershed, the dunefield, the sand sheet, and the sabkha.

Sand Systems

Watershed- The valley flows from alpine tundra and lakes through the Appalpin and Montana woodlands, and sand from the bottom of the valley is captured and transported back to the valley. The recycling of water and wind contributes to the height of the sand.

• Dune field- where the tallest sand hill reside. It is stabilized by opposing wind directions creeks that recycle sand back into it.

• Sand sheet- the largest component of the Great Sand Dunes geological system, made up of sandy grasslands that extend around three sides of the main dune field. The sand sheet is the primary source of sand for the Great Sand Dunes.

• Sabkha- forms where sand is seasonally saturated by rising ground water. When the water evaporates away in late summer, minerals similar to baking soda cement sand grains together into a hard, white crust.

History

• Evidence of human habitation in the San Luis Valley dates back about 11,000 years

• This was toward the end of the last Ice Age, when large amounts of sand and sediment were washing into the valley, and began blowing in the wind as the waters retreated.