Great Sand Dunes National Preserve ⓘ

The newest research suggests that the arrival of the first peoples to North America was much earlier and more complex than previously thought. While the Bering Land Bridge may have been a primary route of entrance from Asia, other routes by boat were likely used as well. The discovery of fossilized human footprints at White Sands National Park dated at 22,000 years BP (Before Present) indicates the first presence of people on the continent significantly earlier than the previous estimates of 13,000 years BP.

One way to trace early peoples is from distinctive stone projectile points that have survived for millennia. In the 1920s, the discovery of Columbian mammoth remains with long spear points near Clovis, New Mexico was the first documentation of mammoth hunting by people in North America. These early nomadic people began to be referred to as the Clovis culture. With the newest research indicating people here perhaps thousands of years before Clovis, archeologists are now identifying a variety of projectile points associated with Pre-Clovis people. Bones from huge prehistoric bison (Bison antiquus) with much smaller, thinner projectile points were found in the same decade near Folsom, New Mexico, prompting the working name of Folsom culture. While not enough is known yet about Pre-Clovis people, Clovis and Folsom may be the same or related people that designed new hunting tools for bison as the mammoth were becoming extinct. Pre-Clovis, Clovis and Folsom cultures are grouped into the Paleo era.

Archeological evidence of Pre-Clovis people at Great Sand Dunes has likely been found, but not yet confirmed as Pre-Clovis. Pre-Clovis projectile points documented from other parts of the continent are quite varied in style, some even resembling points from later eras. The shifting sand environment in many parts of the dunes area does not always maintain stratification representing different millennia, presenting another challenge to positively identifying a Pre-Clovis artifact. Finally, Pre-Clovis research is expanding in North America, but still relatively limited. Evidence at Great Sand Dunes does clearly indicate the presence of both Clovis and Folsom era people here during a wetter, colder time toward the end of the last ice age. Melting glaciers fed the valley with abundant water, creating large wetlands and thick grasses that supported Columbian mammoth and Bison antiquus (large prehistoric bison). As mammoths disappeared due to natural climate change and hunting pressure, Folsom hunters focused especially on Bison antiquus along with smaller mammals.

The atlatl is an ancient tool that uses the laws of physics to achieve far greater velocity in spear throwing by extending the arc of the person's arm. Atlatl darts can achieve speeds over 100 mph (160 kph) with a full-sized atlatl and experienced thrower. Paleo hunters were able to more effectively bring down larger or faster mammals by using this technology. Smaller, thinner, and lighter projectile points such as the Folsom point allowed the dart to travel even farther. Hunting massive Ice Age mammals was dangerous, as mammoth or Bison antiquus could easily kill or severely injure people. Sabertooth cats and huge short-faced bears would also be attracted to the smell of meat and could attack the hunters. In the Paleo era, each person had to have a vast working knowledge of every plant - how it could be processed and used for food, medicine, or fibers. They needed to have tremendous engineering skill to craft perfectly arced projectile points, sewing needles, and countless other items for all aspects of life. They had to know how to predict weather, understand the life cycles and movements of animals and birds, and intimately know the geography of large regions. Finally, they needed to teach this knowledge, share generational stories and lessons, and impart their spiritual beliefs to each new generation.

At a major Folsom-era archeological site in the national park excavated by the Smithsonian over 15 years, at least 49 bison were trapped into a small dune and killed using atlatls. Four to seven families worked together over about a week, processing the meat to dry, preparing foods, crafting new projectile points, and making clothing and tent covers. Based upon the unique stone source materials in each household, it appeared to be gathering of people from different regions. Margaret (Pegi) Jodry of the Smithsonian supervised the excavation of this important site and captured this research in her thesis, Folsom Technological and Socioeconomic Strategies: Views from Stewart's Cattle Guard and the Upper Rio Grande Basin, Colorado . During Paleo times, smaller bands of nomadic family groups would sometimes meet up with other groups to hunt, trade, share information and resources, find spouses for their grown sons and daughters, and perhaps participate in ceremonies or celebrations. Great Sand Dunes has long been a landmark in this region, a unique place to find and meet with others, and a place of bountiful natural resources.

At the beginning of the Archaic era around 8,000 – 6,000 years BP, the climate continued to dry and warm, and few Ice Age mammals were left. Projectile points from this era are generally narrower than Paleo points, likely used to hunt smaller mammals such as elk, deer, and modern bison. Bow and arrow technology was introduced late in the Archaic era, around 1,600 years BP, contributing to the need for even lighter points. Pithouses were a common dwelling for many Archaic-era peoples. A circular pit was dug into the soil, then a square or conical structure of timbers was placed over it, covered by animal hides or brush. A small, seasonal version of a pit house was discovered by archeologists west of the dunefield. Pottery, fishing and agriculture became more prevalent in this era, though the San Luis Valley’s short growing season is not conducive to growing the typical Archaic crops of corn, beans, and squash. Due to harsh winters, Indigenous peoples have historically spent time in the valley spring through fall, most often retreating to lower elevations in winter. About 6,000 years ago, an extremely dry era began, referred to as the Altithermal. There was significantly less human activity here during a roughly 2,000-year span, as edible plants and animals were more scarce. The dunes likely had significant growth during this time, as vegetation on the valley floor withered and sand deposits there became mobile.

Because projectle points have often been emphasized in archaeological studies, so too have male hunting activities. During the Archaic, a proliferation of ground stone tools provides insight into the gathering and plant processing activities of women and children, including horticulture (and later, agriculture), and the deadfall trapping of small mammals. The social, economic, artistic, and spiritual contributions of all members of society can be viewed among a wider array of material objects. Rare discoveries of ancient toys, artwork, jewelry, and even musical instruments give us glimpses into their creativity, relationships, and spirituality.

For many decades, archeologists were mystified by long, tubular rocks found around the dunes. They are now recognized as ancient musical instruments. Called ‘lithophones’ (litho=rock, phone=instrument), they may have filled the evening air with worship or celebrational music around a campfire. Virtually play and listen to these stones on this Colorado Public Radio page .

Hidden among the woodlands and forests of Great Sand Dunes National Park and Preserve are unique living artifacts - trees that were modified by generations of Native peoples. On trees still alive today, this modification is visible through distinct peeled areas left behind on ponderosa pines. The purpose of this peeling is to remove the bark from the tree and use it as a resource. Uses for the outer bark include building materials, cradleboards, or trays. The sap or pitch from the tree is traditionally used medicinally, for waterproofing baskets, and as an adhesive. However, the focus of this resource is to use the inner bark of the pine as food and medicine. At least 200 culturally modified trees have been identified throughout the park and preserve. In 2000, a concentrated grove of 72 modified ponderosa pines just east of the dunefield was added to the National Register of Historic Places as 'Indian Grove'. The National Register of Historic Places is a list of places with significance to American history that are worthy of preservation. With the National Historic Preservation Act of 1966, the National Register was created to protect and preserve these special places. The requirements for National Register designation are a 50-year age minimum and proof that the place has exceptional significance in American history. Living things, such as trees, do not often make the register because many do not meet the age minimum, nor do they retain evidence of human alteration. The modified ponderosa pines within Indian Grove bear this human-altered evidence, or cultural modification, and are up to 500+ years old today.

The inner bark, or cambium layer, of various pines and firs is highly nutritious, containing calcium, vitamin C, and antioxidant properties. Ponderosa pine bark is full of vitamins, minerals, and vital nutrients that have traditionally sustained Native American tribes. Additionally, ponderosa pines smell strongly of vanilla or butterscotch in the spring and summertime, which means their inner bark also tastes sweet. Historically, these trees were often peeled annually by Indigenous groups for their sweet taste and nutritious value. Springtime was the best time to peel the trees because sap is running through the tree and new growth is taking place, making it easier to peel the outer bark layers off. Southern Ute Tribal Elder, Alden Naranjo, described the peeling process saying “they [his ancestors] would cut the bark, make a line across it, then they would take a piece of wood and peel it from the bottom pulling it [the outer bark] apart [from the tree].” Once the outer bark is removed, Native peoples scrape the inner bark off the outer bark slabs and either eat it raw or save it for later use. Inner bark can be ground into flour to make bread, boiled in a tea to cure upset stomachs, or saved in strips to be eaten with salt. Based on those who have tasted the inner bark of a ponderosa pine, the taste and consistency is described to be most like eating raw cane sugar. While the bark is not as sweet as the processed sugar we eat today, like in candy bars or cookies, it has a sweet element and was historically a treat for people to go out and peel the trees each spring.

It is hypothesized that the modified trees at Indian Grove were primarily peeled by Indigenous people because of the groundbreaking research done by archeologist Marilyn Martorano. She was able to determine the peel dates of the trees through dendrochronological analysis, which is the science of tree ring dating. She determined that the trees were peeled from 1777 to the early 1900s with the majority of peel dates taking place from 1820-1879. Based on historical research, there were many Indigenous groups inhabiting the area at this time. After consultation with tribal members, they confirmed that their ancestors peeled trees in the area. According to Alden Naranjo, the Capote band of Utes were the ones who camped in the area where Indian Grove is located, and it is likely that they could have been the people who peeled the trees. However, it could have been any Native American group as many traditionally practice peeling trees and have deep cultural roots to the San Luis Valley and the dunes themselves including Jicarilla Apache, Navajo Nation, and Puebloan peoples. There is a noticeable drop off in peeling activity after 1879. This is because gold and silver were discovered in the San Juan mountains and in the 1880s the U.S. government began relocating Native American tribes to reservations outside of the San Luis Valley. While tribal members would occasionally travel back to peel trees, this was not often and eventually the practice here stopped altogether. Many of the peeled trees at Indian Grove and found throughout the park and preserve are only peeled on one side. There are only a few instances where a tree was peeled more than once or all the way around. If all the outer bark is stripped from the tree, it would be unable to protect itself and it would die. When a tree is peeled, it produces something called rosin which is a sap that coats and hardens over the scar. This acts like a scab that protects the peeled area and keeps insects out of the tree. While this rosin coating is not as effective at protecting the tree as the outer bark layer, it does a pretty good job. Therefore, the tree is able to live for many years after it has been peeled and continues to grow around the peel which is why many of the trees in Indian Grove continue to live today.

Indigenous peoples know that if they peel the whole tree, it will die. Therefore, they only traditionally take as much as they need, and historically left most of the trees living for many years after the peeling event. Since trees are a non-renewable resource, meaning they cannot be replaced as fast as people eat them, why would they not take the whole tree? The reason these trees were intentionally left living is because Indigenous people have a lot of respect for them and the greater purpose they hold. Trees are homes to animals, provide shade, keep the air clean, and are essential pieces to the ecosystem. Native peoples historically relied on the land to sustain them, and they understand the important role trees play in keeping the forest healthy. If you take away the trees, then there will be no forest left to live in. Therefore, the Indigenous ancestors only took what they needed and left the trees living to finish their job and keep the ecosystem strong and healthy for the next generation of people.

Today these peeled trees continue to thrive here at Great Sand Dunes National Park and Preserve as living artifacts that connect modern tribal members to their ancestors and traditions. The National Park Service continues to partner with Native American tribes to protect these living artifacts and continue the mission of the Native Americans who first peeled them by allowing them to live out their natural life cycles. The landscape that these trees live in has seen little change since the days when Native Americans first encountered it and will only continue to remain this way if we all work together to protect it. Therefore, we ask that you practice Leave No Trace protocols, not just at national parks, but at all the places you visit, so that future generations can come and enjoy the places we love so much.

A few of the regional tribal names for Great Sand Dunes: Ute: So-wop-a-wot – ‘where the sand is’ Jicarilla Apache: Seinanyédi – ‘it goes up and down’ Navajo (Diné): Tsé-whíz-hosh – ‘sand comes back down on you’ North America contains the traditional homelands of many Indigenous peoples. Each tribe has distinctive dress, cultural practices, traditional tools and crafts, recipes, music, games, and artwork. Great Sand Dunes' affiliated tribes share their traditional knowledge and culture through consultation with park staff and public programs. For them, this special place is not just a vacation destination, but home.

It is the mission of the National Park Service (NPS) to tell the stories of our country. By conducting tribal consultation, the NPS learns so much more about the landscapes that we are charged with protecting and interpreting. The benefits of the consultation are many, including the transmission of multigenerational cultural knowledge, continuation of traditional use practices resulting in connection with the ancestral landscape, protection of resources by engaging future management partnerships, and communication of Native American perspective and interpretation to the public.

Blanca Peak (14,345 feet/4,372m), located just south of Great Sand Dunes, is one of four sacred mountains to the Navajo (Dine') people. In this 8-minute video podcast, Park Ranger Ravis Henry sings and tells their story of Sisnaajini - the White Shell Mountain, as well as the importance of Great Sand Dunes to his people. For clearest and fastest viewing, choose the best resolution for your connection and device using the icons at lower right. Closed captioning also available. Special thanks to Timothy Begay and Tamara Billie of the Navajo Nation for their ongoing input and consultation with Great Sand Dunes staff. Watch on YouTube: https://youtu.be/yMVRXtfjYuE

Though there were occasional Spanish explorations into the San Luis Valley beginning in the late 16 th century, the first Hispanic settlement here did not occur until 1851, when the town of San Luis was established. In 1598, part of the Juan de Oñate expedition entered the San Luis Valley, probably the first European people to set foot here. In a ceremony that year, Oñate proclaimed the entire Rio Grande watershed as Spanish territory. However, Oñate and his contingent were brutal to Indigenous people of the region, even in the eyes of Spain’s King Philip III, who banished Oñate from the region after hearing news of the Acoma Massacre and other atrocities. Oñate returned to Spain for the remainder of his life. New Mexico Territorial Governor Don Diego de Vargas and his soldiers briefly stayed in the valley in 1694. They saw and hunted a herd of 500 bison before returning to Santa Fe, documenting the historic presence of bison here. In 1776, Juan Bautista de Anza II and a large group of men on horseback passed near the dunes during a punitive raid against the Comanche people. They killed Comanche leader ‘Cuerno Verde’ (Greenhorn) and other Comanches in the Wet Mountains before returning to Santa Fe. The highest mountain in this range is named Greenhorn Mountain after the slain leader. While none of the Spanish explorers mention the dunes in their writings, this massive dunefield at the base of the mountains was likely a landmark for them in an unfamiliar place.

In 1806, US President Thomas Jefferson sent young Lieutenant Zebulon Pike and 20 soldiers to explore the Louisiana Purchase and the origins of the Red River. They rode horses to the Rocky Mountains from St. Louis, returning displaced Osage people to their homeland along the way. At the onset of the winter season in the mountains, Pike’s contingent attempted to climb what later became his namesake mountain, Pikes Peak. Snowstorms forced the party down. Leaving the horses behind, they continued on foot south and then west, looking for a way into the mountains. Following the Arkansas River upstream, they turned into the Wet Mountain Valley, but snow and cold continued to increase. With only their summer uniforms, the men were starving and frostbitten, subsisting on occasional deer or bison, and wrapping bison fur around their bodies for warmth. In these conditions, most would have turned back to lower elevations to seek help, but Pike pushed on. It was now January 1807, the coldest part of winter, with temperatures dropping below zero F most nights. Leaving the most frostbitten men at the eastern base of the Sangre de Cristo Mountains, the group waded through deep snow over Medano Pass, camping at the base of the Great Sand Dunes. Pike wrote: “ When we encamped, I ascended one of the largest hills of sand, and with my glass could discover a large river…The sand-hills extended up and down the foot of the White [Sangre de Cristo] 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…" This is the first known written description of the Great Sand Dunes.

The group continued across the valley floor and built a small fort near the confluence of the Rio Grande and Conejos Rivers. In late winter the men were discovered by Spanish soldiers, who escorted them to Chihuahua (in modern day Mexico) for questioning. They were later released, and all but soldier made it home. After surviving this incredible journey, Zebulon Pike gave his life for his country just a few years later in the War of 1812.

As you gaze across the broad San Luis Valley floor west of the dunes, imagine for a moment it is the 1830s. In the bright sun you see a mule train slowly plodding across sandy grasslands, carrying heavy bundles of woolen blankets. These mules were being led by ordinary people who were making a long, arduous journey through some of the roughest wilderness in North America. As these weary sojourners and animals trudged north, what might they have felt when massive sand dunes appeared ahead of them, piled up against the Sangre de Cristo Mountains? Crossing through sand, grasslands, and wetlands on the San Luis Valley floor was only a small part of a strenuous trek from Santa Fe to California that also included river crossings, canyons, and steep mountain passes. With the threat of raiders, horse thieves, illness, injury, thirst, and hunger, these expeditions reflect tremendous determination and strength that has inspired people for a century and a half.

Established by Congress in 2002 as America’s 15th national historic trail, the Old Spanish Trail route spans six western states, including many locations accessible to the public. At Great Sand Dunes National Park, State Highway 150 and County Lane 6 on the southern border of the park follow or cross some of the Old Spanish Trail routes. Because of sandy, shifting soils, no traces of the trail are visible on the ground near the park today. However, traces of some of the trail’s seasonally varied routes through the valley have been observed from the air. Historical and visual evidence indicates one route passing by Indian Spring, through what is now part of Great Sand Dunes National Park. Before human presence, elk, bison, deer and bighorn sheep had established paths through the mountains and valleys of the West. Native American tribes utilized some of these in making their own trails. The travelers of the Old Spanish Trail followed a few of these trails, and pioneered new paths as needed. Many of these routes are still used today, as hiking trails or highways.

Handcrafted woolen blankets were being produced in what is now New Mexico in the 18th and 19th centuries, but there was little profit from the sale of them there. Foresighted traders knew that they could be traded for needed livestock in California, but the way there was long and treacherous. Some attempts to establish a route began as early as 1776, when the United States was birthed as a nation. In 1826, explorer Jedediah Smith pioneered a trail southwest from the Great Salt Lake into California, but there was still no known viable route known all the way from Santa Fe to California. Late in 1829, Antonio Armijo finally discovered a complete route, leading the first caravan from Abiquiú, New Mexico, to Los Angeles. For the following 20 years, Hispanic and Anglo traders established variants of that first route, including a north branch through the San Luis Valley.

These early travelers frequently traded with Indigenous tribes along the way, although some groups attacked and stole horses or other goods. Established primarily for trade, the trail also felt the footsteps of many native tribes, soldiers, and settlers looking to homestead farther west. The Old Spanish Trail eventually became part of a trail network that also included the Santa Fe Trail and El Camino Real de Tierra Adentro. Santa Fe remained the hub for most southwestern trails. In 1848, the United States acquired most of what are now the southwestern states of this nation. Other routes to California were found, and use of the Old Spanish Trail declined. While some sections are still used today as roads or trails, many visible portions of the trail began to fade back into grasses, soils, and sands.

In 1994, the Old Spanish Trail Association was established “to study, preserve, and protect The Old Spanish Trail.” This non–profit organization has worked in cooperation with the National Park Service, Bureau of Land Management, and local agencies to try to learn more about the trail, and to educate the public about this historic resource. Through the efforts of this group and many other agencies and citizens, Congress established The Old Spanish National Historic Trail in 2002 to interpret the trail’s little–known history, and to preserve the scenic and cultural resources associated with the trail. The National Park Service and Bureau of Land Management are responsible for administration of the historic trail.

Visit the official National Park Service website for Old Spanish National Historic Trail for more information. The latest planning efforts for the national trail, and basic information about its history are available on this site.

John Charles Fremont (1813–1890) worked for the US Topographical Engineers, crossing the rugged terrain of Colorado on various expeditions. As he worked to create maps and discover potential paths for travel, his tenacity earned him the nickname ‘Pathfinder’. Fremont was hired in 1848 to find a railroad route from St. Louis to California. With confidence based upon Zebulon Pike’s 1807 expedition, Fremont led a group of men successfully across Mosca Pass into the San Luis Valley in winter, walking past the Great Sand Dunes. However, they then tried to push on through even deeper snow in the San Juan Mountains to the west. The group became separated, and many died of hypothermia, starvation, or attack by Utes. A complex rescue effort saved some of the men. In 1853, Fremont again tried to find a railroad route through Colorado that would work even in winter months. This time he was successful, crossing the San Luis Valley in December and climbing over the Continental Divide at Cochetopa Pass before continuing on to California. Ironically, after all his work to find a route through the Colorado Rockies, the transcontinental railroad was eventually built through southern Wyoming, a much easier path.

Soldiers from two US forts in the valley patrolled the area around Great Sand Dunes from 1852-1883, protecting both settlers and tribes. Fort Massachusetts was built on the side of Blanca Peak in 1852, but the location was not logistically beneficial. The fort was moved to the valley floor and renamed Fort Garland in 1858. Now a state historic site, Fort Garland Museum and Cultural Center features original buildings and artifacts, dioramas, exhibits, and living history events.

In 1862, soldiers from Fort Garland fought in the pivotal Civil War Battle of Glorieta Pass in northern New Mexico. About 500 Confederate soldiers were working their way north toward Colorado territory, attacking Union forts, in hopes of taking control of the region and its of gold and silver resources. Significantly outnumbered, the Fort Garland soldiers were losing the battle until a group of them slipped behind Confederate lines and burned down Confederate supply wagons. The Confederate soldiers saw the flames behind them and emboldened Union soldiers in front of them, and quickly fled back south to Texas.

Controversial Kit Carson commanded Fort Garland from 1866-1867. During that time, he forged positive relationships with regional Hispanic communities through his wife, Josefa Jaramillo Carson, and with the Ute people through their relationship with Chief Ouray and his wife Chipeta. During negotiations with tribes, tipis were set up near fort buildings.

The Black Buffalo Soldiers that patrolled around the Great Sand Dunes region from 1876-1879 were a later part of that peacemaking mission. As settlers were claiming lands in the San Luis Valley, conflicts with regional tribes continued to erupt. Frontier soldiers had to not only protect the settlers, but also Indigenous peoples of the region. When White settlers began to encroach on lands in southern Colorado promised to the Utes, Buffalo Soldiers were dispatched from Fort Garland to evict them. Today we can only imagine the three-way cultural tension of that moment, as Black soldiers confronted White settlers while Ute people watched in amazement. As young Black men in the 19th century, Buffalo Soldiers knew firsthand the humiliation of prejudice and mistreatment. Though most lacked formal education, these soldiers had a depth of courage, perseverance, and compassion forged through their own suffering and spirituality. It was these characteristics that prompted western tribes to honor them with the name ‘Buffalo Soldiers’. To North American Indigenous peoples, bison are strong and majestic, enduring blizzards, heat and drought. Buffalo Soldiers recognized the positive intention of this unique name, which stayed with these units as long as segregation lasted in the military. These soldiers served so bravely and proudly for the United States that they earned even the respect of many who had initially treated them with contempt. Lieutenant John Pershing observed: “They fought their way into the hearts of the American people.”

South and west of the dunes are portions of the historic Medano and Zapata Ranches, operating since the 1860s. These ranches have a story that extends over a century and a half - from range wars in the 19 th century to a 21st century conservation effort to protect the Great Sand Dunes system. Beginning in the 1860s, Anglo and Hispanic settlers began to homestead this area, competing for land and resources. Wealthier ranchers began buying out - and sometimes driving out - smaller landholders, in a version of the range wars that erupted across the American West. Those who did settle were threatened by attacks from Utes who were still defending this part of their homeland.

The Dickey brothers, who already owned the Medano Ranch, purchased the Zapata Ranch in the early 1870s, combining the ranches. After three decades of frequently changing ownership, the Linger family purchased the ranches in 1911. The Lingers began a new and more stable era of ownership, thriving and raising two generations of children. The Stewart family was next in line to own and operate the ranches from the middle of the 20th century.

Sonny Linger (1928-2013) grew up on the Medano-ZapataRanch and was honored as an inductee of the ProRodeoHall of Fame in 1998 for Lifetime Achievement.

In 1989, new owner Hisa Ota envisioned a new ranch activity - grazing bison on the Medano Ranch. This was the beginning of unique land management and partnerships that would be solidified by the end of the 20th century. Much of the Medano Ranch is now within the boundaries of Great Sand Dunes National Park, helping to conserve and protect the entire geological and hydrological system of the dunes. Bison roam here again as they did for thousands of years.

In 1823, Luis Maria Cabeza de Baca was awarded a large parcel of land by the Mexican government in what is now New Mexico. Eventually, due to complex litigation with the US government, Baca’s claim was swapped with a parcel in Colorado at the base of the Sangre de Cristo Mountains. Ironically, no one in the Baca family ever even visited the Baca parcel in Colorado; it was simply an investment property. In 1862, it was sold by Baca heirs to Territorial Governor William Gilpin for 30 cents per acre. The Baca was leased to various cattle owners for grazing beginning in 1862, but George Adams was the first to fully develop the Baca with fencing, irrigation ditches, sheds and corrals in the 1870s. In the 1980s and 1990s, water developers sought to extract huge quantities of water from the ranch for export to growing Colorado cities. This prompted a complex multi-year process involving local citizens, Congress, The Nature Conservancy, National Park Service, US Fish and Wildlife Service, and US Forest Service. The result was the creation of Great Sand Dunes National Park and Preserve and the Baca National Wildlife Refuge, protecting the integrity of the Great Sand Dunes geological and hydrological system, and simultaneously preserving water for area agriculture. Today, the north side of Great Sand Dunes National Park is former Baca Ranch land. Elk and pronghorn graze here in spacious grasslands with cottonwood-lined creeks at the base of the Sangre de Cristo Mountains.

Four generations of the Herard family defied the odds in remote Medano Canyon above the dunes, successfully maintaining a homestead there. Jean Francois Herard was born in France in 1833, and his wife Julia Babey Herard was born in French Switzerland in 1841. After serving in the Civil War, Jean and Julia came west on the Santa Fe Trail, and likely entered the San Luis Valley via Mosca Pass. They had a daughter, Eupphrasia, and son Ulysses. Tragically, Eupphrasia died at the age of 10 in 1872, the year they arrived in the valley. After moving around the valley for a few years, the family eventually settled in Medano Canyon, where they built a large log home, cabins, corrals, a blacksmith shop, and some outbuildings. They raised cattle in the meadows there, and trout in holding ponds they built. As a young adult, Ulysses took a trip to Texas to purchase horses, where he met and married Mary Dickerson. They had one daughter, Julia, who grew up at the homestead. She had two sons, Jack and Bill Williams, who also spent parts of their lives at the Herard Ranch. Though Julia and then Jack and Bill went to school and had careers in area towns and regional cities, they continued to maintain and live at the homestead when possible.

The Herard family fished and hunted deer to supply their needs, but they were also conservationists of their time, and would not allow the killing of Rocky Mountain bighorn sheep in the canyon. Instead, they hand-fed salt and minerals to the sheep. To this day, the most common place to see bighorn sheep at Great Sand Dunes is beside the Herard homestead site, as if the sheep remember this family’s kindness across the generations. The prominent dome-shaped mountain above the dunes is named Mount Herard in honor of this pioneering family.

The Herard family enjoyed Medano Creek's seasonal flow around the dunes, just as visitors do today. However, it was a much more challenging trip to travel to and from their homestead. The road from Alamosa to the dunes was very rough until improvements were made in the middle of the 20th century. And then they had to to navigate the remainder of the trip on the Medano Pass Primitive Road , through soft sand, creek crossings, and rocks.

Two of the lower routes over the steep Sangre de Cristo Range, Mosca Pass and Medano Pass have been used for thousands of years by Indigenous people as passageways into the San Luis Valley. In the late 19 th century, both were developed into wagon roads, but with hazardous creek crossings and deep sand at its base, Medano Pass was the less desirable of the two. It is now a popular but challenging 4WD driving route over the Sangre de Cristo Mountains. Mountain man Antoine Robidoux took two-wheeled carts across Mosca Pass in the 1820s and 1830s, carrying items to trade with the Ute and other tribes in the region. Robidoux was a US citizen of French Canadian ancestry, born in St. Louis. With Robidoux’s frequent travels here, the pass became widely known as Robidoux Pass for many decades. The trail was slightly improved for cart travel during that time. In 1871, Frank Hastings was awarded a charter to improve the trail over Robidoux Pass into a toll road. A few houses and other structures began to be built at the western base of the pass due to the commerce from travelers. Eventually, the location became a little town called Montville. Settlers in covered wagons, stagecoach companies, traders, Fort Garland soldiers, and mail carriers used the toll road regularly, most stopping for supplies or to mail letters from Montville. In the early 20 th century, the lower portion of the road was significantly damaged in a flash flood. The toll road route eventually reverted to a hiking trail on the west side of the Sangre de Cristo Mountains, but there is still a 2WD vehicle road on the east side of the range.

By the 1880s, Montville had about 15 buildings, including a post office and little general store to supply residents and travelers on the toll road. No structures from Montville are left today, but there are four white posts marking the location of the store along the Montville Nature Trail. Pick up a Montville Trail guide at the Mosca Pass Trailhead to learn more about this historic community. The origin of the name ‘Mosca’ is uncertain. It is the Spanish word for ‘fly’, possibly named for the numerous mosquitoes here in early summer. Or, it may have a different origin. Like the pass, the town of Montville had various earlier names, including Mosco and Moscow City. Luis de Moscoso was an early explorer in the area, so one of the previous names of the pass may have been Moscoso Pass. Though Medano Pass was not used as much as a public road, it was the access road for the Herard Homestead , and they likely maintained it to some extent.

Trujillo Homesteads National Historic Landmark , along with the adjacent Medano Ranch and Zapata Ranch , (below on this page) are listed on the National Register of Historic Places. All three historic ranches are located west of Great Sand Dunes. While the Trujillo Homesteads comprise a small area compared with the 103,000 acre Medano-Zapata Ranches, the Trujillo story plays an integral role in the volatile history of the region during westward expansion of the United States. Hispanic and Anglo homesteaders began settling lands around the dunes in the 1860s. Teofilo and Sofia Trujillo acquired a parcel in the grasslands west of the huge Medano-Zapata Ranch (see below), and grazed sheep there. As was typical of the range wars in the western US in that era, conflict erupted. Cattle ranchers resented what they perceived to be significant range damage caused by sheep grazing. There may have been cultural components to the conflict as well, as Teofilo and Sofia built a traditional adobe-style home and maintained Hispanic customs.

In 1879, their grown son Pedro built a log home nearby that was quite different from his parents’ dwelling. In an interview later in life, Pedro recalled the cultural conflicts between Hispanic and Anglo settlers - and within his own family. The interviewer recorded that Pedro "refused to become a sheepherder, and argued with his father that the sheep would cause him trouble, as that had always been cattle country." Tragically, Pedro's warnings proved true. Teofilo's house was burned down in 1902 by a few area residents, and the Trujillo family relocated to a different part of the valley.

The Linger family purchased the Medano-Zapata Ranches and began a new era of reconciliation in 1911, thriving and raising two generations of children there. Former racial tensions dwindled as they befriended and employed descendants of the Trujillo family. The ranches transitioned into a century of stability and prosperity.

In the photo at left, the Linger children give a wagon ride to their friend Benito Martinez (center), Pedro Trujillo's grandson. Bob Linger recalls: "After the old conflicts between Hispanic sheepherders and Anglo cattlemen, this was a place of restored relationships." Benito and his family lived with the Linger family, who provided ranch positions and friendship to them in an era when it was not the norm.

The restored Pedro Trujillo homestead (pictured), and scattered remains of the Teofilo Trujillo Homestead, are located on the boundary between Great Sand Dunes National Park and the Baca National Wildlife Refuge. This remote site is currently not accessible to the public.

Trujillo Descendants - In Their Own Words (National Park Service Video Interview on YouTube, 10 Minutes)

Descendants of Teofilo and Pedro Trujillo share stories and thoughts about their family's history, and the cultural conflicts that led to the burning down of Teofilo's house in 1902.

Trujillo Homesteads - Digital Flythrough (National Park Service Video on YouTube, 4 minutes)

Liberty and Duncan were 19 th century mining boomtowns established in the foothills north of the dunefield, while Denton Spring is located southeast of the dunefield. Like most boomtowns, their heyday was relatively brief.

In 1874, 23-year-old John Duncan followed in the footsteps of Zebulon Pike and John C. Fremont, crossing the Sangre de Cristo Mountains. But unlike the two earlier explorers, Duncan was seeking gold. He began finding small amounts of ore in the foothills north of the dunes, and advertised the finds to regional newspapers. While Duncan never became wealthy from gold, he sold parcels of land for $75 each, a large sum for that time. By the 1890s, the town of Duncan had a hotel, restaurant, grocery store, general store, clothing store, livery, bakery, bathhouse, and newspaper. At its peak, the community may have housed up to 3,000 residents. George Adams, the owner of the Baca Ranch where the prospecting was occurring, was increasingly resentful of the swarms of people settling in the Duncan area. They were trespassing and taking mineral resources that were not theirs. The case eventually went all the way to the US Supreme Court, which ruled in Adams’ favor. In 1900, US Marshalls came in to evict residents, and conflict erupted. Some miners resisted with guns, and Marshalls retaliated by blowing up cabins. By the end of 1900, Duncan’s last residents had left, and the community suddenly became a ghost town. Homes were dismantled, leaving rock foundations still visible today. Today, only John Duncan’s cabin still stands, restored by the US Forest Service.

Many Duncan residents moved a few miles south off the Baca property, founding the town of Liberty, close to the Great Sand Dunes. Named for the freedom the residents felt in this new location, it boomed for over a decade, with regular stagecoach service, a hotel and school. Eventually it also faded into a ghost town, as gold mining prospects weren’t as rewarding as they were hyped to be. There are a few buildings still standing today at Liberty, but most of the townsite is private property, not accessible to the public.

Liberty and Duncan were larger towns with many amenities, and there are a number of photos documenting people's lives there. However, little is known about the Denton Spring mining community, located in the foothills southeast of the dunes. The little spring itself has been used by Indigenous peoples since ancient times, and elk and deer still visit the spring today for water. Some scattered bricks, planks, and foundation stones are all that remain of this little boomtown.

Japanese settlement in the San Luis Valley historically occurred in three waves. In the early 20 th century, Japanese railroad laborers came to work on the rapidly expanding train system, and some stayed. In the 1920s, a second wave brought Japanese farmers to the valley, where they purchased relatively inexpensive farmland. They worked diligently to develop the land into prosperous farms producing fresh vegetables that were transported by truck and train to markets throughout the US. It wasn’t just land that brought them here to settle. Japanese Americans had endured prejudice and mistreatment on the west coast, but found the people of the San Luis Valley to be generally more welcoming. The Japanese attack on Pearl Harbor only intensified resentment against Japanese Americans. Many were placed in incarceration camps from 1942-1945 and monitored to prevent potential attack from within the US. Some were given the option of relocating to remote rural areas, where they were thought to be less of a possible threat. They just needed to have existing family to sponsor them to relocate and avoid the incarceration camps. With many Japanese Americans already in the San Luis Valley, more came to join them in a third wave of settlement. Though overall it was a kinder environment here than California at that time, the US government still placed restrictions on Japanese Americans, not permitting them to assemble in larger groups, and limiting travel.

After World War 2, Japanese Americans were again fully integrated in the communities of the San Luis Valley. Some of their descendants still live here today. For over a century, they have contributed to the economic, intellectual, and cultural vitality of this region. Watch a video on Japanese settlement in the San Luis Valley. The production of this video was sponsored by the Sangre de Cristo National Heritage Area and the National Park Service.

West of the dunefield, seasonally fluctuating wetlands leave behind white alkali deposits called Trona, similar to baking soda. In the late 19 th century, a tiny community sprang up beside one of the thickest deposits of trona. Residents collected and packaged the soda, then carried it by wagon to Mosca, where it was loaded onto trains. From there it reached various cities where it was sold as washing soda. It is unknown why the production stopped, but today there are a few broken shovels still left laying in the alkali, and planks of small collapsed buildings. It appears that the community was abandoned as quickly as it began.

Little is known about Soda City. Were these bricks part of a house, or a soda processing building?

At least two shovels are still laying in the alkali deposits, possibly indicating residents left suddenly without taking their equipment. Future archeological research may reveal more about this mysterious little community.

A girl walks across the alkali deposit at Soda City, which still had trona left to mine when it was abandoned.

Great Sand Dunes National Monument was established in 1932 by Herbert Hoover, in response to a local citizens' effort spearheaded by the Ladies' PEO chapters in the San Luis Valley . In the 1920s, gold was found in the Great Sand Dunes, and active mining in the sand began to occur. San Luis Valley residents became concerned about long-term protection of the Great Sand Dunes. An intense but remarkably short and successful campaign to gain support and protection for the dunes ensued, culminating in President Hoover's Proclamation: "Whereas it appears that the public interest would be promoted by including the lands hereinafter described within a national monument for the preservation of the Great Sand Dunes and additional features of scenic, scientific, and educational interest…now therefore I, Herbert Hoover…do proclaim and establish the Great Sand Dunes National Monument…"

On November 22, 2000, Congress passed the Great Sand Dunes National Park and Preserve Act of 2000, which authorized the expansion of the national monument into a national park almost four times its original size. Like the proclamation of 1932, it was powered largely by valley residents who banded together to protect the resources important to them. In this era, the resource that was threatened was groundwater, as various companies sought to extract huge amounts of groundwater to pipe to rapidly expanding cities along the Front Range. The legislation authorized the purchase of privately held property from willing sellers for inclusion in Great Sand Dunes National Park. Lands identified as vital to the protection of park resources included the Baca Ranch (see section above), owned for the past two decades by a consortium of commercial water developers. The Baca includes the northwestern corner of the dunefield, wetlands, nesting and migratory bird habitat, and numerous archaeological sites. This purchase, finalized on September 10, 2004, enabled Secretary of the Interior Gale Norton to affirm that "sufficient diversity of resources has been acquired to warrant designation of the land as a national park" on September 13, 2004. Great Sand Dunes National Monument was expanded into a large national park and preserve. As part of the Act of 2000, roughly 42,000 acres of national forest wilderness area were immediately transferred to NPS management, and were renamed the Great Sand Dunes National Preserve. Natural resources in this area are quite different from those in the older national monument or the expanded national park, and include alpine tundra and lakes, subalpine forests, woodlands and streams. The park and preserve now protect most of the dunes’ natural hydrological system, from mountain watershed to wetlands, ensuring "the perpetuation of the entire ecosystem for the enjoyment of future generations." Great Sand Dunes National Park and Preserve is also administered under the provision of the Organic Act of 1916, which specifies that units of the National Park system are: "to conserve the scenery and the natural and historic objects and the wildlife therein…and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations."

Red-breasted nuthatches , along with white-breasted nuthatches and pygmy nuthatches, are sometimes seen walking up and down trees on the Mosca Pass Trail and Montville Trail .

Peregrine falcons nest in high cliffs or forests of the Sangre de Cristo Mountains . In the 1970s, this species was federally listed as endangered. Due to recovery efforts, peregrines were de-listed in 1999. Continued recovery and monitoring efforts continue.

Though they typically nest higher in the mountains, they sometimes glide over the park's entrance road and across the grasslands surrounding the dunefield.

Mountain bluebirds are often seen along the park entrance road, where they hunt for insects in the foothills and grasslands .

They are one of the first birds to arrive in spring, often first appearing in March, the snowiest month of the year.

Hummingbirds are summer residents of the park, nesting in tiny grass nests in the foothills . However, they have been observed feeding throughout the park, from grasslands to alpine tundra, as long as there are flowers present.

Hummingbirds consume large quantities of flower nectar and even aspen sap. To supplement their diet, they also feed on small insects, especially those attracted to sap and nectar.

Four species of hummingbird have been observed in the park (see bird list linked at top of page).

There are hundreds of plant species in the park and preserve, adapted for environments as diverse as alpine tundra and warm water wetlands . View a List of Plants for Great Sand Dunes National Park and Preserve

Below are selected plants found in ecosystems of the park and preserve, beginning with alpine tundra.

Fairy primrose , like most alpine tundra plants, are small, fragile, and close to the ground to survive arctic-like conditions. These magenta-lavender flowers have daisy-like petals.

Alpine avens are one of the most common tundra plants, resembling small yellow buttercups.

Subalpine flowers grow in high, wet meadows surrounded by forest. At left, red Indian paintbrush, white lousewort , and blue-purple penstemon seem to be patriotic with colors of the United States flag. Small aspen daisies at lower left, and yellow western paintbrush at upper left are also part of this natural garden photographed high in the Sangre de Cristo Mountains.

Rocky Mountain juniper trees mix with pinyon trees along the montane foothills of the Sangre de Cristo Mountains.

Inland saltgrass can survive wide variances between water saturation in early summer and dry, salty conditions in late summer. This is the primary type of grass around sabkha wetlands in the park.

While some of the mammals listed on this page visit the dunes on occasion, only Ord's kangaroo rats can live their entire lives in the main dunefield itself. They collect seeds from various grasses and sunflowers, and hide them in moist sand below the surface. After a couple of days collecting moisture, the seeds now provide a little water to these rodents that can live their entire lives without drinking. Kangaroo rats are so named because they can jump up to 5 feet (1.5m) in the air to avoid their many predators. If jumping doesn't work, they may kick sand in their predator's face.

They are active year-round, but are nocturnal. Look for them in the dunefield after dark. Sometimes they are seen scurrying across the park entrance road;

Mule deer are the most commonly observed mammal at the park. They prefer montane meadows and woodlands , right where the campground, entrance station, and Visitor Center are located. Because they are somewhat used to people, they seem to pose for photos. Please do not approach or feed deer; they are still a wild animal. They are prey for mountain lions.

Heavier-bodied than the eastern cousins the white-tailed deer, mule deer are sometimes mistaken for elk by visitors. Elk (see below on this page) are much larger, and have dark, thick fur around their necks.

Black bears are usually black, but may also be cinnamon or blond. They are most often near riparian areas, where they find an abundance of plants and small animals to eat. Mosca Pass Trail hikers occasionally see bears foraging near Mosca Creek. If you encounter a black bear:

Abert's squirrels are jokingly referred to as "scrabbits" because of their rabbit-like ears. They are found only in coniferous montane forests .

The Abert's squirrel is named after Colonel John James Abert, an American naturalist of the 19th century.

Abert's squirrels live in and eat various parts of the ponderosa pine, including seeds, inner bark, cones, and buds. They also consume mushrooms, carrion, bones, and antlers.

The dunes were formed by the right combinations of wind, water, and sediment. Creeks and streams brought in large amounts of sediment and sand into the valley. Wind then blew the sand toward the bend in the Sangre de Cristo Mountains, where opposing storm winds helped squeeze the sand into the tall dunes you see today. While this explanation does answer in the question above, the story of how the Great Sand Dunes were formed is much more complex, and as new research discoveries occur each year, is continually evolving. Below is a summary of what most geologists currently understand to be the broad series of events that took place in the formation of these massive dunes.

Through the breaking apart and movement (rifting) of large surface plates on Earth's surface, the Sangre de Cristo Mountains were uplifted in the rotation of a large plate. Fossils from the bottom of an ancient sea are now preserved in high layers of rock in the Sangre de Cristos, illustrating the scale of the uplift. The San Juan Mountains were created through volcanic activity. With these two mountain ranges in place, the San Luis Valley was born, covering an area 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 flood events.

In 2002, geologists discovered lake shoreline 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. They named this body of water "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 River, likely forming the steep Rio Grande Gorge near Taos, New Mexico.

After Lake Alamosa drained away, smaller lakes still covered the valley floor, including two broad lakes in the northeastern side of the valley. Streams from both mountain ranges have continued to bring sand to the depressions where the lakes form. In the past, this included the Rio Grande. Lake Alamosa, the subsequent smaller lakes, and Rio Grande have fed sand to Great Sand Dunes for the past 400,000 years. The dune sand extends to depths of 300 feet below the valley floor and just above Lake Alamosa deposits, indicating that there have been dunes here since the time of Lake Alamosa. Remnants of these large lakes are still here today, in the form of sabkha (alkali flat) wetlands and playa lakes.

When the lakes periodically dry, sand left behind blows with the predominant southwest winds toward a low curve in the Sangre de Cristo Mountains. The wind funnels toward three mountain passes here - Mosca, Medano, and Music Passes - and the sand accumulates in this natural pocket. Sand grains are a perfect size for the winds to move. Sediment grains larger than sand are too heavy to be moved by the wind, while grains smaller than sand are light enough to be picked up and held by the wind and carried away. Sand grains on the other hand, are light enough to be picked up by the wind, but heavy enough that wind typically can’t keep them in the air, so the sand bounces along the surface of the valley floor, moving along, and gathering together in locations where the wind is slowed, or an obstacle is in the way. Environments where wind moving sediment is the dominant process are called aeolian environments. 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, and make it difficult for the dunes to migrate into the mountains.

As time went on, the wetlands and playa lakes (lakes that grow and shrink periodically with water availability) played an important role in the formation of the dunes. Much of the sediment that had been brought into the valley from the mountains was unsorted, having a mixture of grain sizes and materials, including muds, silts, clays, and most importantly sands. These smaller bodies of water and seasonal lakes helped sort the sand from the rest of the sediment. When the lakes and wetlands are full, sand is deposited near the edges, forming little sandy beaches. As water levels lower, the sand is then exposed to wind, allowing the aeolian processes to take over. This created a continual sand source for the growing dunes for quite some time, allowing the dunes to accumulate enough sand to reach their current massive size.

Even with the opposing storm winds, most sand is still blown toward the mountain ranges. Here, two seasonal mountain streams , Medano Creek and Sand Creek, 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. Water from these creeks then reappear in near the southwestern edge of the park, feeding into the wetland and playa lake systems. Learn more about the hydrology of Great Sand Dunes .

This 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. There are other dunes in Colorado, and in most western states in the US, but none as tall (741feet/ 226 meters) and none as dramatic. Here giant dunes rise in front of the alpine Sangre de Cristo Mountains, while streams flow across the sand seasonally, making for an unusual and unexpected sight.

Currently, there is enough vegetation on the valley floor that there is little sand blowing into the main dunefield from the valley. However, even today there are still some small parabolic dunes that originate from the playa lakes in the sand sheet and migrate across grasslands , joining the main dunefield . At other times, some of these migrating dunes become covered by grasses and shrubs and stop migrating. This limits the amount of new sand entering the main dunes system. The lack of new sand coming in suggests that the overall size of the dunefield isn’t growing, but the dunes within are constantly moving in complex patterns. It is possible that lots of new sand enters the dunefield when climatic conditions decrease the vegetation on the sand sheet, such as during an ice age, when it’s cold or during extremely dry periods. Compare the two photos below showing the first ridge of the dunes 138 years apart. The overall appearance of the dunefield is similar suggesting that they do not change much over a couple of human lifespans. The dunes at Great Sand Dunes form on different scales and develop on differing timeframes. The scene shows a large ridge, or megadunes with smaller individual dune ridges developed on it. Twenty years of GPS measurements shows that individual dune ridges are constantly on the move. The movement is highly variable and can be as little as a few feet per year to tens of feet in a day. Individual dunes are very mobile and move across the larger form, but it takes much longer for the overall shape of the megadune to change noticeably. There are 5 megadunes in the dunefield. The one pictured is the Medano Creek megadune and it formed in response to sand supplied by Medano Creek.

Scientists don’t yet know a precise age and estimates have changed over time. At one time they were thought to be very young and the result of glacial outwash. We have since learned that the dune sand extends hundreds of feet into the subsurface, so they are older than initially believed. The dune sand begins just above the clay deposits of Lake Alamosa, so if Lake Alamosa disappeared about 400,000 years ago, then there have been dunes here since then. It is also possible that there is more dune sand under the lake deposits. We haven’t drilled that deep yet. Keep in mind that the dunes we see today are young and may have come from glacial outwash as recently as 12,000 years ago that flooded the modern playa system. The best answer is the dunes on the surface are young as they are constantly forming, but since the sand goes deep into the subsurface, there have been dunes here for a long time.

You may also learn about geological components of the Great Sand Dunes system , hydrology of Great Sand Dunes , and the variety of dune types in the park.

Geologic Map of Great Sand Dunes National Park (USGS/Madole, VanSistine, Romig; 2016) Valdez A., Zimbelman J.R. (2020) Great Sand Dunes. In: Lancaster N., Hesp P. (eds) Inland Dunes of North America. Dunes of the World. Springer, Cham. https://doi.org/10.1007/978-3-030-40498-7_7 The Geologic Story of Colorado's Sangre de Cristo Range (USGS/Lindsey; 2010)

2007 Rocky Mountain Section Friends of the Pleistocene Field Trip: Quaternary Geology of the San Luis Basin of Colorado and New Mexico, September 7–9, 2007 (USGS online publication) Michael N. Machette, Mary-Margaret Coates, and Margo L. Johnson

Geoindicator: Dune Formation and Reactivation (web page, Global Change Research and Information Office)

Complete List of Mammals, Reptiles, Amphibians, and Fish of Great Sand Dunes National Park and Preserve

Below are some of the characteristic mammals of the park and preserve.

They build nests up to about 2 feet (61cm) wide, where they raise 2-5 young. Abert's squirrels are only active in daylight hours; at night they retreat to their nests to sleep.

Mountain lions are rarely seen by park visitors, but their tracks are often seen along Medano Creek and Sand Creek, where they hunt mule deer at night. In winter their tracks are also seen in snow in montane woodlands along the foothills.

Pronghorn can run at speeds up to 60 mph (97kph) across the park's grasslands . Visitors sometimes see a herd of pronghorn along the park entrance road in morning or evening.

Males have tall, curved horns; females have smaller, straighter horns. While mule deer tend to stay closer to trees and shrubs, pronghorn prefer open grasslands. They can survive on little or no drinking water for extended times by having highly efficient kidneys.

Elk prefer open grasslands , avoiding forests when possible. In the San Luis Valley, they may seasonally migrate up into montane meadows or alpine tundra, but some herds stay on the valley floor year-round. In the western U.S., a combination of encroachment on grassland habitat via development, and maturing closed-canopy forests has had an effect on their distribution.

There are estimated to be over 4000 elk in the eastern part of the San Luis Valley.

American pikas live primarily on the alpine tundra of Great Sand Dunes National Preserve . They spend their summers gathering mounds of grass to dry in the sun, then stay active all winter under the snowpack eating their summer's work. Unlike their lower-elevation cousins in the rabbit family, pikas have small ears and feet, a characteristic of warm-blooded animals living in cold locations. A 2024 research project, Lagomorph Ladders: Assessing a Multi-Host Community and Potential for Spillover of Rabbit Hemorrhagic Disease at Great Sand Dunes National Park and Preserve (accessible pdf, 8 mb) , examined whether rabbits are spreading hemorrhagic disease to pikas.

Yellow-bellied marmots are familiar to those who hike to the summits of mountains in Colorado. These heavy-set creatures eat large amounts of food in summer to survive the long hibernation of an alpine winter. In summits where there are many hikers, marmots become bold and occasionally try to steal lunches! They are recognized by their short whistling call.

Marmots are found in alpine tundra and subalpine forests in Great Sand Dunes National Preserve .

Bighorn sheep are found throughout subalpine forests in Great Sand Dunes National Preserve ; they are most commonly seen along the Medano Pass Primitive Road . In summer months, some groups may migrate higher to alpine tundra .

Male bighorn sheep are called "rams", with thick spiral horns that are used to battle other males during mating season. Unlike antlers, horns grow throughout the animal's life.

Female bighorn sheep are known as "ewes", with slender, straighter horns. They give birth to lambs in spring, sometimes right onto the snow.

Snowshoe hares are found in subalpine forests of the Sangre de Cristo Mountains, where they are preyed upon by mountain lions, coyotes, and bobcats.

These plump mammals have large, wide feet that work like snowshoes on deep snow. White in winter and brown in summer, they are sometimes missed by hikers because of their camouflage.

Beavers on sand dunes? Occasionally a beaver will wander across the sand from their usual riparian habitat, perhaps dispersing to a new home in a pond or stream miles away. In 2007 a beaver swam through the main "beach" area of Medano Creek along the base of the dunes ( photo ). A few other beavers have been photographed or documented on the dunes or in isolated interdunal ponds.

About 2000 bison are currently managed within park boundaries on land owned by The Nature Conservancy . This private inholding is currently not open to the public.