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Great Sand Dunes National Park and Preserve is one of the most biologically and geologically diverse parks in the United States.
During the Paleozoic Era, over 500 million years ago, shallow seas and river systems deposited sedimentary materials throughout the region. Eons later, pressures from within the Earth pushed the landscape high above sea level, limiting sedimentary deposition and leaving a gap in the region's Mesozoic record. Around 40 million years ago, an arid landscape dominated where rivers and intermittent lakes emerged and subsided upon the land. Recurring lava flows poured onto the landscape about 34 million years ago from volcanic vents in the San Juan mountains, creating a subsurface layer that geologists call the Conejos Formation. Rapid uplift of the Sangre de Cristo Mountains began about 19 million years ago. Rifting associated with the uplift widened the valley and caused its floor to drop significantly. (This process continues today.) Around five million years ago, a new series of volcanic activity rocked the region, at times damming rivers that flowed out of the southern half of the San Luis basin. The Pleistocene began 1.8 million years ago as climate changed globally. Glaciers grew in mountain valleys, some pouring ice and rock far into the San Luis Valley. Many scientists consider the Pleistocene to be the period in which dune formation began in the San Luis Valley. Only about 12,000 years ago, a warming climate melted many glaciers worldwide and signaled the end of the Pleistocene. Large quantities of silt, gravel and sand were carried by rivers and streams into the San Luis Valley. Today, the rivers and creeks continue to transport sediment into playa lake systems which are sources of sediment for dune-forming winds of the San Luis Valley.
Originating as snow on 13,000' peaks, Medano and Sand Creeks cascade first into high lakes situated at timberline, then flow through dense spruce and fir forest, beaver meadows dotted with mountain wildflowers, large aspen and cottonwood groves, ponderosa forest, massive dunes, and spacious desert grasslands. The water seems to disappear in the sand—only to reappear as ponds and verdant wetlands on the west side of the dunes. At only a few places in the world can one experience "surge flow", a stream flowing in rhythmic waves. Three elements are needed to produce the phenomenon: a steep enough grade to give the stream a higher velocity; a smooth, mobile surface with little resistance; and sufficient water to create surges. In spring and early summer, these elements combine to make waves at Great Sand Dunes. As water flows across sand, sand dams or 'antidunes' form, gathering water. When the water pressure is too great, the dams break, sending down a wave. In wet years, waves can surge up to a foot high! At only a few places in the world can one experience "surge flow", a stream flowing in rhythmic waves. Three elements are needed to produce the phenomenon: a steep enough grade to give the stream a higher velocity; a smooth, mobile surface with little resistance; and sufficient water to create surges. In spring and early summer, these elements combine to make waves at Great Sand Dunes. As water flows across sand, sand dams or 'antidunes' form, gathering water. When the water pressure is too great, the dams break, sending down a wave. In wet years, waves can surge up to a foot high!
Great Sand Dunes National Monument and Preserve encompasses a stunning diversity of life zones—journey from sand to alpine areas, all within a day’s hike! Climb from the arid sabhka and sand sheet of the valley floor, past the dunes and into piñon-juniper woodland, through shaded montane forest and finally onto the cool tundra of 13,000 foot mountain peaks.
Common Birds: Mourning Dove, Common Nighthawk, Northern Flicker, Western Wood-Pewee, Warbling Vireo, Horned Lark, Violet-green Swallow, Mountain Chickadee, Red-breasted Nuthatch, White-breasted Nuthatch, Pygmy Nuthatch, Golden-crowned Kinglet, Western Bluebird, Hermit Thrush, Sage Thrasher, Yellow Warbler, Yellow-Rumped Warbler (Myrtle), Western Tanager, Green-tailed Towhee, Chipping Sparrow, Brewer's Sparrow, Vesper Sparrow, Dark-eyed Junco (Oregon), Western Meadowlark
Mammals: Pronghorn, Bighorn Sheep, Pika, Marmot, Black Bear, Mountain Lion, Wolverine, Ord's Kangaroo Rat, Rocky MOuntain Elk, Bison, Water Shrew, Prairie Dogs, Mule Deer, Jack Rabbits, Beaver, Weasels, Pine Martens, Coyotes, Bobcats
Human Beings have known about, visited, or lived near the Great Sand Dunes for a long, long time. The oldest evidence of humans in the area dates back about 11,000 years. Some of the first people to enter the San Luis Valley and the Great Sand Dunes were nomadic hunters and gatherers whose connection to the area centered around the herds of mammoths and prehistoric bison that grazed nearby. Although we don't know the names or the languages of those earliest people, modern American Indian tribes were familiar with the area when Spaniards first arrived about 400 years ago. The traditional Ute word for the Great Sand Dunes is sowapophe-uvehe, "The land that moves back and forth." Jicarilla Apaches settled in northern New Mexico and called the Dunes ei-anyedi, "it goes up and down." The first known writings about the Dunes appear in Zebulon Pike's journals of 1807. As Lewis and Clark's expedition was returning east, U.S. Army Lt. Pike was commissioned to explore as far west as the Arkansas and Red Rivers. Gold and silver rushes occurred around the Rockies after 1853, bringing miners by the thousands into the state and stimulating mining businesses that operate to this day. Numerous small strikes occurred in the mountains around the San Luis Valley. The idea that the Dunes could be destroyed by gold mining or concrete-making alarmed residents of Alamosa and Monte Vista. By the 1920s, the Dunes had become a source of pride for local people and a potential source of tourist dollars for local businesses. Members of the Ladies PEO sponsored a bill to Congress asking for national monument status for the Great Sand Dunes. Widely supported by local businesses and Chanbers of Commerce, the bill was signed into law in 1932 by President Herbert Hoover.
