History of the Park Area

Scientists are not quite sure when the dunes started to form, but it likely occurred very recently, geologically speaking, just 450,000 years ago or later. Through a series of volcanic eruptions and tectonic uplift, a large high altitude valley was created between the San Juan and Sangre de Cristo Mountains. Over time, the valley filled with water from the annual snow melts in the mountains, creating an enormous high altitude lake scientists have dubbed Lake Alamosa covering over 1500 square miles. (To give some perspective of that size, if it existed today it would be the 6th largest lake in the U.S. after the Great Lakes and the Great Salt Lake.) The waters would have also eroded the mountains, carrying sediments and sands into the lake from the the mountains. In perhaps a cataclysmic failure of the lake's natural dam, the waters of the lake were probably responsible for carving the 800 foot deep gorge of the Rio Grande found at the southern end of the San Luis Valley west of Taos, New Mexico. With much of the lake now gone, prevailing westerly winds began blowing the sand from the former lake bed against the Sangre de Cristo Mountains, but the mountains were too high for the sand to be carried over the range. Sands that blew up onto the mountainsides was carried back down by snowmelt fed streams not unlike waters that carried sands into the lake for millions of years. The result of these two competing forces was that the sand piled up and over time built up into sand dunes, the highest of which now reaches 750 feet above the valley floor.

The earliest evidence of human inhabitation of the area dates to 11,000 years ago, but the earliest accounts we have of people living in the valley come down to us from Spanish explorers more than 300 years ago. The two tribes known to have been living in the valley then were the Utes and the Jicarilla Apache. Both tribes considered the area sacred (one of the four sacred mountains of the Navajo is Blanc Peak just to the southeast of the park) and the area around the dunes was used as a hunting ground and a place to collect layers of bark from ponderosa pines, which were used as food and in medicines. Over 100 of these ponderosa pine trees in the park show evidence of this peeling process. To the Utes, the dunes were called Sowapophe-uvehe, "the land that moves back and forth." The Jicarilla Apache also named the dunes after their movement, calling them Sei-anyedi, which means "it goes up and down."



A view of the dunefield from an elevated position. The dunes cover about 39 square miles.

In succession, Spaniards and them Americans settled in the valley. The Americans arrived in waves of miners looking for gold and other valuable minerals, homesteaders seeking to farm the land and finally ranchers using the grasslands to graze cattle. A substantial section of the valley was granted to the heirs of a Spanish land grant holder, Luis Maria Cabeza de Baca, whose patent to land totally roughly a half million acres had been deprived of them by the establishment of a little town in modern day Nevada you might have heard of, Las Vegas. In compensation for relinquishing their claims to the land, the United States government, in 1860, granted the heirs five tracts of land in the New Mexico Territory. Tract Number 4 was located in the San Luis Valley and soon fell within the boundaries of the newly created Colorado Territory. Like the other four tracts given by the U.S. as compensation, this tract consisted of 99,289.39 acres (about 155 square miles). Tract No.4 was quickly sold and became a ranch raising Hereford cattle. It remained a ranch for over 100 years until a corporation acquired the land and decided to plunder the vast aquifer of water sitting below it. This and a subsequent attempt to drain the aquifer by a later owner were both thwarted thanks to local opposition and political pressure in Colorado state government.

The court battles over the water bankrupted the owner, at which point the Nature Conservancy came in and purchased the old Baca Ranch. In conjunction with the federal government and the state of Colorado, a plan was put forth to Congress to take the existing Great Sand Dunes National Monument, created by President Hoover in 1932, and expand it into a national park, taking in all of the areas crucial to the cycle of water I'll be explaining in a bit. In 2000, Congress authorized the park's creation instructing the Secretary of the Interior to establish the park once "sufficient land having a sufficient diversity of resources" was acquired under federal control.

For four years, the land issues were worked out with the various agencies involved, the National Park Service, the Forest Service, the Fish and Wildlife Service, the State of Colorado and the Nature Conservancy. The old Baca Ranch was split in three, with authority over the largest piece, 53,000 acres, being transfered to the NPS along with a portion of the Rio Grande National Forest in the Sangre de Cristo Mountains to form the National Park and Preserve. In compensation, 13,000 acres of the Baca Grant became part of the national forest with the remaining acreage forming the core of the newly created Baca National Wildlife Refuge.

The Cycle of Water

Each winter, snow fall entombs the summits of the Sangre de Cristo Mountains. In the spring, these snows melt and replenish a series of small alpine lakes high in the mountains.

The outflow of these lakes work their way down the mountain in creeks and streams, the most important of which is Medano Creek. The waters of Medano Creek come down from the mountains flowing through subalpine and montane forets before sweeping along the eastern and southern edges of the dunefield at the base of the mountains, providing water to an assortment of plant and animal life along the way. They make the forests of aspens, cottonwoods, dogwoods and pines possible. The waters of the creek get absorbed by the sands and begins an underground journey that can take years.



Medano Creek makes its way through its annual bed at the base of the dunes. Part of the snowcapped Sangre de Cristo Mountains are in the background.

The creek also has another side feature that is found only a few places on earth. Because the creek flows over sand, as the current carries the water, small ridges of sand form in the creek called anti-dunes. When the ridges collapse you get waves that appear to move upstream against the creek's natural flow and against gravity. The waves are called surge flow. The water itself really isn't flowing backwards, but the wave action does, creating a really cool sort of optical illusion. I was just in the park this May and got to see the flow in action.



A surge flow is starting to move at the left edge of the frame moving to the right, but the flow of the water is from right to left.

All this water flowing into the dunes area keeps the dunes wet, at least underneath. The San Luis Valley is technically a desert, getting only about 10 inches of precipitation a year, but dig in the dunes just a few feet and you will hit wet sand. The dunes protect this valuable water from being evaporated away by arid high winds that sweep across the valley. The moisture held in the sand makes life in the dune fields possible, supporting a plethora of insects and small mammals. It also attracts larger mammal visitors to the dunes such as pronghorn, bison, coyotes and bobcats.



A pronghorn antelope forages in the grasslands south of the dunefield.

The water flows westward, underground first through the dunefield and then through the sand sheet underneath. Scientists estimate the dunefied makes up only 3-10% of the sand volume present in the San Luis Valley, the rest being spread out into the so called sandsheet, hundred of feet think in some places. Eventually, the elevation of the valley drops below the the seasonally changing water table of the underground flow. When it does in a region called the sabkha, it creates small lakes that support saltgrass marshes with plentiful insect and amphibian life. This in turn attracts birds. As some of the water evaporates away, it leaves behind alkali soda deposits that form a protective crust that prevents additional evaporation. Finally, the water completes in's journey emerging in a vast network of wetlands. They support even more life than the sabkha and support crucial grasses to bison, elk and pronghorn while providing nesting areas for diverse species of birds from shore birds like sandhill cranes, great blue herons and avocets to birds of prey such as bald eagles, golden eagles and burrowing owls. The waters here evaporate and move west on the winds, but the moisture is unable to clear the 14,000 foot peaks of the Sangre de Cristos, instead falling back to earth as rain or snow in the mountains, continuing the cycle.



Baca National Wildlife Refuge (image courtesy USFWS)

It is because of this cycle that efforts were made to protect the water resources in the system within a national park. Removing water from the system en masse could have had disastrous results for the valley's delicate ecosystem, interrupting the cycle and cascading its affects on thousands of species of plants and animals, humans included. The national park and preserve contains bits of all components of the ecosystem and the neighboring Baca National Wildlife Refuge protects and manages the wetlands that are not part of the park.

Unfortunately this protection is not complete enough as much of the old Baca Ranch's mineral rights are still in private ownership. While the park protects those areas within its boundaries, the NWR doesn't have similar authority to protect its subsurface minerals from "exploration" and extraction. The mineral owners want to drill for oil and gas in the NWR and since 2006 have pursued the necessary permits and environmental assessments. A second set of assessments was required after activists showed that the company wanting to drill, Lexam Explorations, exerted undue influence over the first assessment. The second draft assessment was issued this January. In April, the 45 day public comment period ended with a finding that there would not be significant impact by drilling, but imposed 43 regulations on the driller including restrictions upon what time of year drilling can occur to prevent interference with the migratory birds and the calving season of the wildlife. The regulations are also intended to prevent contamination of the ground and surface waters and abate noise pollution created by the drilling. Environmentalists remain concerned.

This has been yet another entry in the Park Avenue Thursday National Parks diary series. Other diaries in this series include:





A more tourist-oriented series runs on Tuesday, our "Things To Know Before You Come..." diaries, chosen by Daily Kos users from our Friday "Photo Friday & Open Thread" diaries. Finally, we also have a Saturday series on our state parks.

You can see all of the Park Avenue diaries on the Park Avenue blog page, where you can also click on the "Follow" link to follow the blog entries on your own page, or get an RSS feed of the blog.