Great Sand Dunes II


15 miles north of Blanca Peak, a Colorado sand dune field emerged as a result of the last major volcanic activity in the San Juan Mountains some 30 million years ago. As the Rio Grande carried volcanic ash eastward, prevailing southwesterly winds – offset by the Sangre de Cristo Mountains’ snowmelt – maintained the unique balance of these trapped dunes:  shifting back and forth according to the strength and direction of the prevailing wind relative to the degree of the snowmelt’s runoff.

Reaching heights of 750′, these are the highest and tallest sand dunes in North America.

Native Americans have long observed this unique dune field’s wandering, shifting nature: the Jicarilla Apaches: “it goes up and down,” and the Utes: “the land that moves back and forth.”

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