Great Sand Dunes

The Great Sand Dunes' creation goes back to about 12,000 years ago when the last Ice Age ended. In the San Juan Mountains, sand that had been ground down by glaciers and trapped in ice during that frigid period was now freed, allowing the prevailing winds from the west and southwest to carry the sand particles across the San Luis Valley.

The winds have continued to erode the San Juans, creating additional fodder for the dunes. The Sangre de Cristos lie uncharacteristically low between Medano and Mosca Passes, and consequently, the wind funnels through this area of lesser topography and on to the east. However, even this lower section of the Sangres rises over three thousand feet above the valley floor.

Before the winds can travel up and over the range, they must release their burden of heavy sand, resulting in the accumulation and creation of the Great Sand Dunes in the crook of the Sangres between the Mount Herard massif and the Sierra Blanca.
The winds pick up sand from another source outside of the San Juans.

The mountains are majestic as a back drop for the sand dunes!