Great Sand Dunes National Park and Preserve

Great Sand Dunes National Park and Preserve
IUCN category II (national park)
Great Sand Dunes
Location	Saguache County and Alamosa County, Colorado, United States
Nearest city	Alamosa
Coordinates	37°43′58″N 105°30′44″W
Area	149,028 acres (603.09 km2)
Established	September 13, 2004
Visitors	388,308 (in 2016)
Governing body	National Park Service
Website	Great Sand Dunes National Park and Preserve

Great Sand Dunes National Park and Preserve is a United States National Park located in the San Luis Valley, in the easternmost parts of Alamosa County and Saguache County, Colorado. Originally created as Great Sand Dunes National Monument on March 17, 1932, Great Sand Dunes National Park and Preserve was established by an act of the United States Congress on September 13, 2004. The park includes 107,342 acres (167.7 sq mi), and the preserve protects an additional 41,686 acres (65.1 sq mi).

History

Park map

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 area were nomadic hunter-gatherers whose connection to the area centered around the herds of mammoths and prehistoric bison. They were Stone Age people who hunted with large stone spear or dart points now identified as Clovis and Folsom points. These people only stayed when hunting and plant gathering was good, and avoided the region during times of drought and scarcity.

Modern American Indian tribes were familiar with the area when Spaniards first arrived in the 17th century. The traditional Ute phrase for the Great Sand Dunes is Saa waap maa nache, "sand that moves." Jicarilla Apaches settled in northern New Mexico and called the dunes Sei-anyedi, "it goes up and down." Blanca Peak, just southeast of the dunes, is one of the four sacred mountains of the Navajo, Sisnaajini. These various tribes collected the inner layers of bark from ponderosa pine trees for use as food and medicine. The people from the Tewa/Tiwa-speaking pueblos along the Rio Grande remember a traditional site of great importance located in the San Luis Valley near the dunes: the lake through which their people emerged into the present world. Sip'ophe, meaning "Sandy Place Lake", is thought to be the springs and/or lakes immediately west of the dunefield.

In 1694, Don Diego de Vargas became the first European known to have entered the San Luis Valley, although herders and hunters from the Spanish colonies in present-day northern New Mexico probably entered the valley as early as 1598. De Vargas and his men saw and hunted a herd of 500 bison, apparently in the southern part of the valley, before returning to Santa Fe. In 1776, Juan Bautista de Anza and an entourage of men and livestock probably passed near the dunes as they returned from a punitive raid against a group of Comanches. At this time, the San Luis Valley was a travel route between the High Plains and Santa Fe for Comanches, Utes, and Spanish soldiers. For some of them, the dunes were likely a visible landmark along the trail.

The first known writings about Great Sand 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. By the end of November 1806, Pike and his men had reached the site of today’s Pueblo, Colorado. Still pushing southwest, and confused about the location of the Arkansas River, Pike crossed the Sangre de Cristo Mountains just above the Great Sand Dunes. His journal from January 28th, 1807, reads: "After marching some miles, we discovered ... at the foot of the White Mountains [today’s Sangre de Cristos] which we were then descending, sandy hills…When we encamped, I ascended one of the largest hills of sand, and with my glass could discover a large river [the Rio Grande] …The sand-hills extended up and down the foot of the White Mountains about 15 miles, and appeared to be about 5 miles in width. Their appearance was exactly that of the sea in a storm, except as to color, not the least sign of vegetation existing thereon."

In 1848, John C. Frémont was hired to find a railroad route from St. Louis to California. He crossed the Sangre de Cristos into the San Luis Valley in winter, courting disaster but proving that a winter crossing of this range was possible. He was followed in 1853 by Captain John Gunnison of the Corps of Topographical Engineers. Gunnison’s party crossed the dunefield on horseback.

In the years that followed, the Rockies were gradually explored, treaties were signed and broken with resident tribes, and people with widely differing goals flooded into Colorado from the United States and Mexico. In 1852, Fort Massachusetts was built and then relocated to Fort Garland, about 20 miles southeast of the Great Sand Dunes, to safeguard travel for settlers following the explorers into the San Luis Valley. Although many settlers arrived in the San Luis Valley via the trails from Santa Fe or La Veta Pass, several routes over the Sangre de Cristo Mountains into the San Luis Valley were well-known to American Indians and increasingly used by settlers in the late 1800s. Medano Pass, also known as Sand Hill Pass, and Mosca Pass, also called Robidoux’s Pass, offered more direct routes from the growing front-range cities and dropped into the San Luis Valley just east of the Great Sand Dunes. Trails were improved into wagon routes and eventually into rough roads. The Mosca Pass Toll Road was developed in the 1870s, and stages and the mail route used it regularly through about 1911. That year, the western portion was badly damaged in a flash flood. Partially rebuilt at times in the 1930s through the 1950s, it has been repeatedly closed by flooding and is now a trail for hikers.

Medano Creek

The Herard family established a ranch and homestead along Medano Creek in 1875, using the old Medano Pass Road to travel to and from their home. The modern road, open only to 4WD, high clearance vehicles, follows the old route, skirting the dunefield before rising to Medano Pass and continuing east into the Wet Mountain Valley. The Herards grazed and bred livestock in the mountain meadows, built a home, raised horses, cattle, and chickens, and established a trout hatchery in the stream. Other families homesteaded near the dunes as well, including the Teofilo Trujillo family, who raised sheep west of the dunes, and Frank and Virginia Wellington, who built the cabin and hand-dug the irrigation ditch that parallels Wellington Ditch Trail, just south of the park campground.

Gold and silver rushes occurred around the Rockies after 1853, bringing miners by the thousands into the state and stimulating mining businesses that are still in operation. Numerous small strikes occurred in the mountains around the San Luis Valley. People had frequently speculated that gold might be present in the Great Sand Dunes, and local newspapers ran articles in the 1920s estimating its worth at anywhere from 17 cents/ton to $3/ton. Active placer mining operations sprang up along Medano Creek, and in 1932 the Volcanic Mining Company established a gold mill designed to recover gold from the sand. Although minute quantities of gold were recovered, the technique was too labor intensive, the stream too seasonal, and the pay-out too small to support any business for long.

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 P.E.O. Sisterhood sponsored a bill to Congress asking for national monument status for Great Sand Dunes. Widely supported by local people, the bill was signed into law in 1932 by President Herbert Hoover. Similar support in the late 1990s resulted in the monument’s expansion into a national park and preserve in 2000-2004.

Geography

Great Sand Dunes National Park is located in the San Luis Valley while its namesake National Preserve is located to the east in an adjacent section of the Sangre de Cristo Range of the Rocky Mountains. Elevations range from 7,515 ft (2,291 m) in the valley to the west of the dunes, to 13,604 ft (4,146 m) at the summit of Tijeras Peak in the northern part of the preserve. The dune system covers an area of about 30 sq mi (78 km²). The forested and often snowcapped mountains exceeding 13,000 ft (4,000 m) to the east are the most prominent feature besides the dunes. Other features include several snow-fed creeks originating high in the mountains and two spring-fed creeks in the sand sheet. Several small lakes create a wetland in the sabkha section to the southwest of the dunes.

The main dunefield measures roughly 4 mi (6.4 km) east-to-west and 6 mi (9.7 km) north-to-south, with an adjacent 6 sq mi (16 km²) area to the northwest called the Star Dune Complex, making a total of about 30 sq mi (78 km²). The park and preserve together are approximately 15 mi (24 km) east-to-west at the widest point, and approximately 15 mi (24 km) north-to-south, also at the widest point. The park encompasses 107,342 acres (167.7 sq mi), while the preserve protects an additional 41,686 acres (65.1 sq mi) for a total of 149,028 acres (232.9 sq mi).

The Rio Grande National Forest is located to the north and southeast while the remaining forested slopes directly to the east of the dunes were redesignated the Great Sand Dunes National Preserve. The San Isabel National Forest is located to the east of the preserve just beyond the ridge of the Sangre de Cristo Range. Private property abuts most of the southern boundary of the park while the San Luis Lakes State Wildlife Area lies adjacent to the southwestern corner of the park. The Baca National Wildlife Refuge lies to the west and private property of the Baca Grande subdivision of Crestone lies adjacent to the northwest.

Geology

From Star Dune, the tallest dune in the park

The park contains the tallest sand dunes in North America, rising to a maximum height of 750 feet (229 m) from the floor of the San Luis Valley on the western base of the Sangre de Cristo Range. The dunes cover an area of about 30 sq mi (78 km²) and are estimated to contain over 5 billion cubic meters of sand.

Creation of the San Luis Valley began when the Sangre de Cristo Range was uplifted in the rotation of a large tectonic plate. The San Juan Mountains to the west of the valley were created through extended and dramatic volcanic activity. The San Luis Valley encompasses the area between the two mountain ranges and is roughly the size of the state of Connecticut. Sediments from both mountain ranges filled the deep chasm of the valley, along with huge amounts of water from melting glaciers and rain. The presence of larger rocks along Medano Creek at the base of the dunes, elsewhere on the valley floor, and in buried deposits indicates that some of the sediment has been washed down in torrential flash floods.

In 2002, geologists discovered lakebed deposits on hills in the southern part of the valley, confirming theories of a huge lake that once covered much of the San Luis Valley floor. The body of water was named Lake Alamosa after the largest town in the valley. Lake Alamosa suddenly receded after its extreme water pressure broke through volcanic deposits in the southern end of the valley. The water then drained through the Rio Grande, likely forming the steep Rio Grande Gorge near Taos, New Mexico. Smaller lakes still covered the valley floor, including two broad lakes in the northeastern side of the valley. Large amounts of sediment from the volcanic San Juan Mountains continued to wash down into these lakes, along with some sand from the Sangre de Cristo Range. Dramatic natural climate change later significantly reduced these lakes, leaving behind the sand sheet. Remnants of these lakes still exist in the form of sabkha wetlands.

Aerial view of the dunes and the Sangre de Cristo Range

Sand that was left behind after the lakes receded blew with the predominant southwest winds toward a low curve in the Sangre de Cristo Range. The wind funnels toward three mountain passes here—Mosca, Medano, and Music Passes—and the sand accumulates in this natural pocket. The winds blow from the valley floor toward the mountains, but during storms the winds blow back toward the valley. These opposing wind directions cause the dunes to grow vertically. Two mountain streams—Medano and Sand Creeks—also capture sand from the mountain side of the dunefield and carry it around the dunes and back to the valley floor. The creeks then disappear into the sand sheet, and the sand blows back into the dunefield. Barchan and transverse dunes form near these creeks. The combination of opposing winds, a huge supply of sand from the valley floor, and the sand recycling action of the creeks, are all part of the reason that these are the tallest dunes in North America.

Sufficient vegetation has grown on the valley floor that there is little sand blowing into the main dunefield from the valley; however, small parabolic dunes continue to originate in the sand sheet and migrate across grasslands, joining the main dunefield. Some of these migrating dunes become covered by grasses and shrubs and stop migrating. The dunes system is fairly stable as the opposing wind directions balance each other out over time. Also, the main dunefield is moist beneath a thin layer of dry surface sand. While the top few inches of sand are blown around during windstorms, the moist sand remains largely in place.

Scientists estimate that Lake Alamosa disappeared about 440,000 years ago, but the dunes themselves apparently originate from sand deposits from later, smaller lakes. A relatively new dating process, optically stimulated luminescence (OSL), is still in development. This method takes core samples of sand from deep within a dune, and attempts to measure how long quartz grains have been buried in the dark. If the deepest sand deposits can be accurately dated, the age of the dunes could be determined. Samples of sand from deep in the dunes have returned OSL dates varying between a few hundred years to tens of thousands of years old.

The dunes contain dark areas which are deposits of magnetite, a mineral that has eroded out of the Sangre de Cristo Range. This black mineral is composed of iron oxide, so magnets are able to pick it up. Because magnetite is also relatively heavy, the lighter weight sand is blown away on windy days leaving magnetite behind in patches. These black patches can be seen in the dunefield from a distance.

Climate

The Great Sand Dunes are located in the high elevation desert of the San Luis Valley, just west of the Sangre de Cristo Mountains. The summer high temperatures are atypical for a desert area as the average high temperature is only slightly above 80 °F (27 °C) in the warmest month of July; however, the large spread between high and low temperatures is typical of a high desert climate. Low temperatures during winter nights can be extremely cold, with average low temperatures well below 32 °F (0 °C) and record low temperatures below 0 °F (−18 °C) from November through April. Precipitation is very low on the dunes, averaging just 11.13 inches (283 mm) of rainfall per year. The high evaporation rates on the dunes qualify the area as a desert, even though precipitation exceeds 10 inches (250 mm). Snow falls on the dunes as well, but snow melts quickly as the average high temperature is above freezing throughout the year.

Climate data for Great Sand Dunes National Park and Preserve
Month	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Record high °F (°C)	67 (19)	63 (17)	72 (22)	78 (26)	89 (32)	96 (36)	94 (34)	90 (32)	87 (31)	80 (27)	67 (19)	60 (16)	96 (36)
Average high °F (°C)	35.1 (1.7)	39.2 (4)	46.8 (8.2)	56.3 (13.5)	66.2 (19)	76.6 (24.8)	80.8 (27.1)	77.9 (25.5)	71.5 (21.9)	60.5 (15.8)	45.5 (7.5)	36.4 (2.4)	57.7 (14.3)
Daily mean °F (°C)	22.4 (−5.3)	26.5 (−3.1)	33.9 (1.1)	42.1 (5.6)	51.5 (10.8)	60.9 (16.1)	65.6 (18.7)	63.2 (17.3)	56.6 (13.7)	46.1 (7.8)	32.8 (0.4)	23.9 (−4.5)	43.79 (6.55)
Average low °F (°C)	9.8 (−12.3)	13.9 (−10.1)	21.0 (−6.1)	28.0 (−2.2)	36.8 (2.7)	45.2 (7.3)	50.5 (10.3)	48.5 (9.2)	41.7 (5.4)	31.7 (−0.2)	20.1 (−6.6)	11.3 (−11.5)	29.9 (−1.2)
Record low °F (°C)	−25 (−32)	−22 (−30)	−9 (−23)	−6 (−21)	15 (−9)	25 (−4)	31 (−1)	33 (1)	22 (−6)	2 (−17)	−12 (−24)	−19 (−28)	−25 (−32)
Average precipitation inches (mm)	0.44 (11.2)	0.37 (9.4)	0.77 (19.6)	0.89 (22.6)	1.09 (27.7)	0.86 (21.8)	1.79 (45.5)	2.00 (50.8)	1.22 (31)	0.86 (21.8)	0.49 (12.4)	0.36 (9.1)	11.13 (282.7)
Average snowfall inches (cm)	6.8 (17.3)	5.3 (13.5)	8.3 (21.1)	5.7 (14.5)	1.4 (3.6)	0 (0)	0 (0)	0 (0)	0.1 (0.3)	2.6 (6.6)	4.7 (11.9)	5.6 (14.2)	40.5 (102.9)
Source: www.wrcc.dri.edu/summary/climsmco.html

Ecology

Flora

There are hundreds of plant species in the park and preserve, adapted for environments as diverse as alpine tundra and warm water wetlands. Trees include aspen, Douglas fir, pinyon pine, ponderosa pine, Rocky Mountain juniper, three-leaf sumac, bristlecone pine, red osier dogwood, and narrow-leaf cottonwood.

Among the flowering plants are alpine phlox, dwarf clover, alpine forget-me-not, fairy primrose, alpine aven, Indian paintbrush, lousewort, blue-purple penstemon, aspen daisy, western paintbrush, elephantella, snow buttercups, Smith's draba, scurfpea, Indian ricegrass, blowout grass, prairie sunflower, Rocky Mountain beeplant, rubber rabbitbrush, speargrass, small-flowered sand verbena, narrowleaf yucca, prickly pear, and ring muhly. Inland saltgrass is the primary type of grass around sabkha wetlands in the park.

Fauna

Elk at Big Spring Creek

Mammals include—from alpine tundra to low elevation grasslands—the pika, yellow-bellied marmot, bighorn sheep, black bear, snowshoe hare, Abert's squirrel, cougar, mule deer, water shrew, beaver, kangaroo rat, badger, pronghorn, and elk. Over 1500 bison are currently ranched within park boundaries on private land owned by The Nature Conservancy which is only open to the public through tours.

Over 200 species of birds are found throughout the park. From higher to lower elevations and dependent on season, some of the bird species include the brown-capped rosy finch, white-tailed ptarmigan, red-breasted nuthatch, peregrine falcon, mountain bluebird, northern pygmy owl, dusky grouse, hummingbird (four species), western tanager, burrowing owl, bald eagle, golden eagle, sandhill crane, American avocet, and great blue heron.

Various reptiles live in the park, such as the short-horned lizard, fence lizard, many-lined skink, bullsnake, and garter snake.

Fish encountered in the park's streams include the Rio Grande cutthroat trout, Rio Grande sucker, and fathead minnow.

Amphibians include the tiger salamander, chorus frog, northern leopard frog, spadefoot toad, Great Plains toad, and Woodhouse's toad.

The park harbors at least seven endemic insects: the Great Sand Dunes tiger beetle, a circus beetle, Werner's ant-like flower beetle, Triplehorn's ant-like flower beetle, an undescribed species of clown beetle, an undescribed species of noctuid moth, and an undescribed species of robber fly. More than a thousand different kinds of arthropods (insects and spiders) have been found at the Great Sand Dunes.

People climbing high dunes

Features

The park contains the tallest sand dunes in North America, rising to a maximum height of 750 feet (229 m). The park also contains alpine lakes and tundra, mountain peaks over 13,000 feet (3,962 m) in elevation, mixed conifer forests, grasslands, and wetlands.

Medano Creek, which borders the east side of the dunes, never finds a permanent and stable streambed as fresh sand falls in the creek. Small underwater sand ridges that act like dams form and break down, creating surges of water which resemble waves. The surges occur at an average interval of about 20 seconds. In a high-water year, the surges can be as high as 20 in (51 cm). The "surge flow" mainly occurs during the peak flow period from late May to early June in most years.

Big Spring Creek is a unique spring-fed creek formed by an unconfined aquifer which creates wetlands that support rare species and plant communities in a generally arid area. The creek was designated a National Natural Landmark in 2012.

Recreation

Getting to the dunes requires walking across the wide and shallow Medano Creek. The creek typically flows past the main dunes parking area from late April through late June, with peak flow occurring from late May to early June in most years. Before and after the peak flow period, the water is only a few inches deep. Hiking is permitted throughout the dunes, with the warning that the sand can get very hot in the summer, up to 150 °F (66 °C). Sand wheelchairs are available at the visitor center. Sandboards and sand sleds can be rented just outside the park entrance or in Alamosa which is the closest city.

Medano Pass Road is a 22 mi (35 km) four-wheel drive (4WD) road that begins where the main park road ends. The unpaved road crosses Medano Creek nine times and traverses 4 mi (6.4 km) of deep sand. Only street-licensed 4WD motor vehicles or motorcycles, and bicycles are permitted. Fat tire bikes are the best type of bicycle due to the sandy stretches. The road winds around the eastern side of the dunefield, up through a forested mountain canyon inside the National Preserve, and then over 10,000 ft (3,000 m) Medano Pass at the 11.2 mi (18.0 km) mark. The road then continues down into the Wet Mountain Valley and connects with Colorado State Highway 69. Travellers are advised that hunting is permitted in the National Preserve during the months of autumn.

Unlike all other national parks in the contiguous United States, Great Sand Dunes National Park includes a preserve which allows hunting. Sport hunting has regulations which include not pursuing a wounded animal if it enters the park and not hunting inside national park boundaries. Mountain lion hunting with dogs is also allowed in the preserve, but unless the dogs have spotted the lion and are pursuing it, they are required to be leashed. Other game species include turkey, bear, bighorn sheep, elk and mule deer.

Designations

Map demarcating the National Park area (dunes) and the National Preserve (mountains)

The Great Sand Dunes was initially designated a National Monument which combined various types of protected areas to satisfy the objectives of the National Park Service, the Nature Conservancy and other organizations, and to combine conservation and sustainable use of the ecosystem. The result was similar to the protected area mosaic recommended in the early 1980s for parts of the Yukon in Canada. Implementation was staged, with many interactions and adaptations over time.

The dunes and surrounding area were designated a National Monument in 1932 after a bill—sponsored by the P.E.O. Sisterhood and widely supported by local residents—was signed into law by President Herbert Hoover. Similar support in the late 1990s resulted in the monument’s re-designation as a National Park and Preserve in 2000-2004.

With the help of the Nature Conservancy, the federal government purchased 97,000 acres (39,000 ha) of the Baca Ranch, which in effect tripled the size of the park. The purchase includes those sections of the ranch which previously bordered the park on the north and west sides and also included 14,165-foot (4,317 m) Kit Carson Peak and 14,080-foot (4,292 m) subpeak Challenger Point, and the water drainages to the south. The land purchased was split into three sections. Part of the Sangre de Cristo Mountains would be transferred to the Rio Grande National Forest, another section to the west would be set aside as a wildlife area and would host a wild bison herd and the last section to the east would be transferred from the Rio Grande National Forest and would be designated as a National Preserve open to regulated seasonal hunting.

Wide view of the dunes with people at right in foreground

External links

• Great Sand Dunes National Park and Preserve (National Park Service)
• Explore Parks – Great Sand Dunes (National Parks Foundation)
• Pinon Flats Campground (Recreation.gov)
• Friends of the Dunes (non-profit citizen's support group for Great Sand Dunes)
• Alamosa Convention & Visitors Bureau