It’s called the Rocky Mountain State, and mountains are its primary attraction – range after range of big, beautiful, skyscraping peaks laid down in ancient seas, rivers, floodplains, and deserts over millennia, thrust up and tilted by volcanism, etched by glaciers, and eroded away by time. In few other places is alpine scenery so alluring. Frigidly beautiful throughout the snowy winter, when skiers flock to the slopes. Gray and austere on the windy summits after spring melt, when nature slowly begins to wake up. Skirted in phosphorescent green meadows and brilliant wildflowers in summer, and splashed with aspen golds in fall, when warm temperatures attract hikers, campers, bikers, horseback riders, and four-wheel-drivers.
Red rock formations in the Garden of the Gods.
Carol M Highsmith
Perhaps it is because there are so many of them that Colorado’s numerous mountain ranges seem so majestic. That, and the fact that 54 of the state’s peaks top 14,000ft (4,270 meters), with many more clearing 12,000ft (3,660 meters). No doubt about it, this is America’s Switzerland.
View of the San Juan Mountains.
Nowitz Photography/Apa Publications
Varied terrain
Other than the mountains, what is less known about Colorado’s geography is that it is remarkably diverse. The state is shaped like a large rectangle. To the east, the Great Plains meet the sawtooth peaks of the Front Range like an ocean lapping against the wall of a giant medieval fortress. At the southeastern end of the Rockies, between the plains and the San Juan Mountains, stretches the massive San Luis Valley, an extension of the volcanic Rio Grande Rift Valley, which lies to the south, in New Mexico.
Most dramatic of all is the meeting of two geological provinces on the Western Slope: the Rocky Mountains and the 130,000 sq miles (340,000 sq km) of horizontal sedimentary rocks that make up the Colorado Plateau. Cracked by faults, uplifted by volcanism, and downcut by the river system for which it is named, this unique mile-high plateau of redrock mesas, buttes, and deep, shadowy canyons makes a spectacular counterpoint to the Rocky Mountains, rising to the east.
Parks and rivers
At 100,000 miles (260,000 sq km), Colorado is the eighth largest state in the Union. It is joined by Wyoming to the north, Utah to the west, Arizona to the southwest, New Mexico to the south, and Kansas to the east. The different ranges that make up the Rocky Mountains cover much of the state. Running through Rocky Mountain National Park and down through the central San Juan Mountains of the Southern Rockies is the nation’s Continental Divide, where major river systems flow east or west. The Colorado River and its tributaries – the Green, Yampa, Dolores, Gunnison, and Animas rivers – flow west to the Pacific Ocean. The Arkansas and North and South Platte rivers and the Rio Grande flow east to the Atlantic.
Sandstone formations rise above the Yampa River in Echo Park, part of the Canyons section of Dinosaur National Monument.
Bigstock
The making of the Rockies
The towering Rockies on view today have their origins in geologic events that go back to the dawn of life on Earth. The oldest rocks in Rocky Mountain National Park and Dinosaur National Monument, for example, were laid down at least 1.8 billion years ago as sea sediments, which gradually hardened into horizontal sedimentary limestone strata. These Precambrian Era sedimentary rocks were later subjected to a long period of volcanism. Intense heat and pressure forced the soft sedimentary rocks to undergo a metamorphosis into hard gneisses and schists. Later intrusions of hot magma formed a core of crystalline igneous granite intrusions in these rocks. During the next 1.5 billion years, they were uplifted repeatedly, worn down into plateaus by erosion, and covered by sediments.
The Ancestral Rockies did not make their first appearance until the Pennsylvanian Period (325 to 280 million years ago), when a phase of mountain building, known as the Colorado Orogeny, lifted up two huge mountain islands – Frontrangia and Uncompahgria – in the midst of another inland sea. These Ancestral Rockies were much higher than the modern Rockies, with huge basins between and west of the ranges.
As the climate warmed and dried, during the Permian Period (280 to 240 million years ago), the inland sea withdrew to the west, leaving behind salt deposits several miles thick. Rainwater attacking the new mountains created streams and rivers that abraded red iron-rich sediments, carrying them from the highlands into the basins, initially mingling with the salt in colorful bands and later forming thick redbed deposits.
Natural resources
Colorado is rich in gold, silver, lead, coal, oil, gas, and uranium and has long attracted miners to its lands. Early prospectors concentrated on extracting placer deposits of native gold flakes found in stream gravels and sands in the South Platte River near Denver. When these deposits played out, the prospectors sold their stakes to large mining companies with the deep pockets and latest equipment to reach lodes, or veins, of gold deep underground. Silver was discovered in the 1860s, creating overnight boomtowns in places like Silverton and Creede, followed by veins of lead and zinc, uncovered during searches for gold and silver in the San Juan Mountains. Uranium, found in western Colorado near Paradox, is associated with the fossil-rich Chinle and Morrison formations. Following World War II, company towns like Unavan became one of the country’s major producers of carnotite, which yields uranium as well as vanadium. Unavan and other uranium towns remained in business until the 1980s, when local production was no longer profitable. Small, rich deposits of oil, gas, and coal have also lured energy companies to western Colorado since the early 1900s. The Piceance Basin, north of Grand Junction, contains huge quantities of oil shale laid down in the mud of a lake 50 million years ago.
One of these huge basins, the Paradox, straddled what is now the Colorado–Utah border on the edge of what’s called Canyon Country. Its basement formation, the “Paradox salt formation,” became so compressed by later sedimentary deposits, the salt actually became plastic and began to move away from the overburden, doming up along faults, entering joints in the rocks, and dissolving in groundwater. As joints widened, groundwater created long fins in the sandstone that wind and ice sculpted into the arches and other famous landmarks in Colorado National Monument and Utah’s Arches National Park. In Colorado, the eroded sandstone formations at Red Rocks Park, west of Denver, are far older, part of the original redbed deposits shed from the Ancestral Rockies, 300 million years ago.
The geology of buildings
Ever wondered about the geology of buildings? David Williams has. In Stories in Stone, he devotes one chapter to William Brown’s gas station in Lamar, Colorado. Built in the 1930s, the 15 by 35ft (4.5 by 10.5-meter) structure is made of 100 pieces of petrified wood gathered from a wash south of town and set in a castellated pattern reminiscent of a miniature castle. The Lamar Daily News raved: “Here is a building worthy of study… observe these marvelous trees… they stand to remind you of the ancient ages long ago, and to serve you with the modern fluid which is the vital touch of our ultra-modern motor-age.”
Dinosaur haven
Throughout the Triassic period (240 to 200 million years ago), erosion continued to wear down the Ancestral Rockies, and the warming climate and withdrawal of the sea left behind broad floodplains and deltas. The Age of Fishes now gave way to the Age of Reptiles – huge dinosaurs such as the platey-backed Stegosaurus, the state emblem. Large and small dinosaurs sloshed about in the floodplains and marshes of northwestern Colorado, which, as the continents drifted on their red-hot sea of magma, far below the surface, was close to where West Africa is today.
Little-visited Dinosaur National Monument in northeastern Colorado preserves not only one of the country’s largest caches of dinosaur fossils but also 2 billion years of geological strata, the most intact record in the National Park System.
Enormous conifers and cycad ferns grew in the humid conditions, becoming compressed into soft shales that would eventually yield some of the country’s largest deposits of oil, gas, and coal in northwestern Colorado. During a major flood at a river crossing near the location of present-day Green River, hundreds of dinosaurs were wiped out as they tried to ford the swollen waterway. These unfortunates were buried in the river sediments where they died, gradually becoming entombed in the pale crumbly Morrison Formation. The skeleton of one of these dinosaur casualties – a brontosaur – was discovered in the early 1900s by Carnegie Museum paleontologist Earl Douglas (for more information, click here), just north of Jensen, Utah. Other museums quarried specimens for display until, in 1906, President Theodore Roosevelt set aside Dinosaur National Monument to halt the removal. The embedded bones of other dinosaurs are on display in the newly constructed Quarry Exhibit Hall, near Quarry Visitor Center at the monument.
Dinosaurs are exhibited and explained at the Museum of Nature and Science.
Nowitz Photography/Apa Publications
The modern landscape
The contemporary Rockies arose just as the Age of Dinosaurs was giving way to the Age of Mammals at the end of the Cretaceous period, 65 million years ago. In a now familiar ritual, giant blocks of ancient crystalline rock, overlaid by younger sedimentary rock, broke and were thrust upward. The origins of this major mountain building period lay to the west, off the present-day California coast, where the oceanic Pacific Plate continues to dive under the North American Plate, forcing up the Sierra Nevada and coastal mountains.
These distant seismic movements substantially changed the topography of the Interior West. Stretching and thinning of the earth’s surface east of the Sierra Nevada created the Basin and Range topography of the Mojave Desert around Death Valley. In the Southwest, reverberating plate movements wrinkled the earth’s surface into huge sedimentary uplifts known as monoclines, such as Utah’s Waterpocket Fold, and in Colorado created the Rockies. Although they would be leveled once more by erosion, most of the structure of the Rockies came into being during this period of intense mountain building, known as the Laramide Orogeny. Now, where a great sea had lain 100 million years ago, the Great Plains appeared. As rivers and streams eroded materials from the highlands, it shed into this vast basin to the east. Eventually, sediments more than 13,000ft (4,000 meters) thick would cover what is now Kansas and the other Midwestern states.
Carved by the Gunnison River through the Gunnison Plateau a million years ago, Black Canyon of the Gunnison National Park is deeper, narrower, steeper, and younger than the Grand Canyon, Yosemite, or Yellowstone.
The Rockies that are visible today did not appear until between 80–50 million years ago, during the Miocene-Pliocene Uplift, when faulting and regional upwarping lifted the Rocky Mountain Front Range as much as 5,000ft (1,500 meters) to its present height. In southwest Colorado, ongoing volcanism during the Oligocene Epoch, 28 million years ago, created the San Juan Mountains, or Southern Rockies. This volcanism, which formed the major peaks of the San Juans and San Luis Valley, continues to affect western Colorado and accounts for the numerous geothermal hot springs found along faults in the western San Juans.
Getting into hot water
Although they are found all over the state, hot springs abound in the western Rockies, where they have long been sacred to Native Americans. In southwestern Colorado, Pagosa Springs was used by Ancestral Puebloans living at nearby Chimney Rock. Later, it was called pagosa, or “big healing waters,” by Southern Utes who revered the steaming pools. Utes and Arapahos laid down their arms and bathed together at Manitou Springs in northwestern Colorado. And in the western San Juan Mountains, Ouray, chief of the Northern Utes, frequently bathed in the hot springs in the town that now bears his name, in order to ease his arthritis.
Some 50 known thermal springs rise along faults in the volcanically active Rocky Mountains, ranging in temperature from 68°F (20°C) to 181°F (83°C). Rustic resorts have grown up around many of these hot spots. Some, such as clothing-optional, family-run Orvis Hot Springs, south of Ridgway, remain pleasantly low-key, while others, such as those in Steamboat Springs, Ouray, and Pagosa Springs, have been developed into popular public facilities with attached therapy rooms. Colorado’s best-known hot springs are Glenwood Springs, where the 90°F (32°C) pool is two soccer fields long, the largest in the world. During the 2000 Winter Olympics, the Olympic torch was swum through the pool en route to Salt Lake City.
Lava lands
It is hot magma rising along faults at the edge of the Rocky Mountains and Colorado Plateau that has helped give the landscape of the Four Corners its distinctive appearance. In western Colorado, the ancient Uncompahgre Uplift that created the Ancestral Rockies forced up the Uncompahgre Plateau, which has been gradually exposed as the Colorado River and its tributaries cut into it. Where hot lava reached the surface within the last couple of million years, it frequently sits atop sedimentary rocks from eons of inland seas, beaches, rivers, and streams. Southwest of Grand Junction, Grand Mesa is the largest lava plateau in the world. Just to the south, the Gunnison River has carved a pathway through an enormous lava dome at Black Canyon of the Gunnison National Park and created an awe-inspiring, black chasm nearly a mile deep.
The glacier-carved peaks of Maroon Bells.
Dreamstime
Where overlying sedimentary rocks were thickest, hot magma welling up along faults domed up the landscape but never reached the surface. The resulting humped formations, known as laccoliths, encircle the large basins adjacent to uplifted areas. One good place to see them is at Far View Visitor Center at Mesa Verde National Park in southwestern Colorado. Nearby Sleeping Ute Mountain and more distant Navajo Mountain have been sacred landmarks for native people for centuries. In some instances, erosion has completely stripped away the sedimentary rocks, revealing the volcanic cores of these formations. Ship Rock, which plays a major role in the origin stories of the Navajo, is clearly visible in the 25,000 sq mile (65,000 sq km) San Juan Basin, south of the San Juan River.
The ever-shifting dunes of Great Sand Dunes National Monument at the base of the Sangre de Cristo Mountains.
Nowitz Photography/Apa Publications
The power of ice
In the Rockies, the main erosional force has been four periods of glaciation, which began during a cooling trend early in the Quaternary Period, 2 million years ago, and continued until the end of the Ice Age, 10,000 years ago. In Colorado’s higher valleys, snow became compacted into rivers of ice, or glaciers, which began to flow down the narrow valleys. Telltale signs of their passage can be seen throughout the Rockies. River-cut V-shaped ravines have been widened into characteristic U-shaped valleys. Peaks have been carved into jagged pinnacles, knife-edge aretes and bowl-like depressions known as cirques that frequently fill with meltwater.
The relentless grinding of glaciers scoured the valleys, leaving behind striations, grooved and polished surfaces caused by transported rocks. Some boulders, aptly known as erratics, were marooned atop smooth granite in the high country. Other rock debris, called moraine, was carried into the lower valleys. A distinctive feature of glaciated valleys is the way moraines have been deposited. As the glaciers made their way down the valleys, debris (or till) has left behind lateral moraines. Glacial till is most visible at the bottom of valleys, where melting glaciers finally drop their largest load of eroded material as a terminal moraine. Frequently in such places, glacial meltwater has created crystal-clear lakes filled with blue-green glacial flour, made up of suspended ice particles.
Not all lakes in the high country were created by glacial moraines. The lake that gave Lake City in the San Juans its name was formed when a mud slide, the Slumgullion Earthflow, slid off the mountains and blocked the Gunnison River. Rock slides are common throughout the high country of the Rockies, where flows of massive boulders spill down steep mountainsides.
Most mobile of all are the soils that have shed from the San Juan Mountains and been carried through San Luis Valley by the Rio Grande. As the river changed course, the sandy deposits were left victim to the powerful southwesterly winds that blow through the valley. Sometimes reaching more than 40mph (64km/h), these winds scoop up the grains of sand and buffet the 14,000ft (4,270-meter) Sangre de Cristo Mountains. The sand is too heavy to funnel through the mountain passes. As the winds continue their passage out of the valley their sandy cargo is left cradled at the base of the foothills, creating sand dunes 700ft (215 meters) high, the tallest in America. The area is preserved within Great Sand Dunes National Park and Preserve.
Heritage tourism
Today, Colorado is renowned as much for its family farms and markets, and ancient cultural attractions, as for its superb skiing.
For struggling farmers, ranchers, and others in Colorado’s rural areas, many of whom have worked the land for generations, ecotourism has become an important lifeline during tough times. Assisted by an innovative state heritage program, regional tourism hubs, and direct marketing on the internet, many have taken control of their own destinies, offering numerous interesting activities, from horsemanship, cattle drives, and trail maintenance to you-pick produce, egg gathering, and harvest dinners featuring local food and wine.
Southwestern Colorado is famous for its archeological heritage. At Crow Canyon Archeological Center near Cortez, you can take part in an ongoing archeological dig at a significant Pueblo site near Mesa Verde National Park. Kelly Place, a very reasonably priced bed-and-breakfast in McElmo Canyon, has 25 archeological sites on its 40-acre (16 -hectare) property and offers professionally guided tours of other archeological sites in the area. At the other end of the spectrum, Canyon of the Ancients Guest Ranch rents luxury vacation homes, and you can even pick your own produce for supper. After the Pueblo people moved on in the late 1200s, they were supplanted by the Ute Mountain Utes, whose reservation abuts Mesa Verde just south of Cortez. Regular tours to Pueblo ruins on the reservation are conducted by tribal guides. It’s a unique and rugged way of viewing less well-known ruins and learning about Ute culture.
Birding and bed-and-breakfasts
Southern Colorado’s San Luis Valley, southeast of Salida, is one of the most isolated areas of Colorado. It remains a tightly knit Hispanic region, in the shadow of the Spanish Peaks, where many inhabitants still speak an archaic form of Spanish and live in adobes, grow beans and grain, and ranch cattle. Its main attraction is Great Sand Dunes National Park and Preserve, which protects the tallest sand dunes in North America and is a migratory corridor for sandhill cranes and other birds. An unusual way to enjoy the valley is to stay at The Nature Conservancy–owned Zapata Ranch, a working cattle and bison ranch adjoining the park. Visitors learn about wildlife and horsemanship and assist with the herds.
With 400 of 625 North American bird species using Comanche National Grasslands, southeast Colorado is an important birding destination. It is also a magnet for historians interested in the Santa Fe Trail. The Cimarron Cutoff branch of the trail passed directly through here, and Bent’s Fort was located directly on it to take advantage of trail traffic. Picketwire Canyon, known for its unusual dinosaur tracks, and Picture Canyon, a rock art site, are both scenic and historic attractions. Canyon Journeys Tours can arrange hiking and driving tours and lodging in the area.
Park County, located in the central Rockies, contains the highest gold and silver mines in the country, as well as a variety of historic ranches, mining towns, and scenic railroads. An hour from Denver, it is immensely popular for driving tours amid spectacular scenery. Como, Breckenridge, Fairplay, Alma, and other communities offer a taste of mountain living. Historic bed-and-breakfasts like the Como Eating House/ South Park Hotel, built by the railroad in the old depot, have high-country character to spare, while an increasing number of historic ranches, including the 1880s Tarryall River Ranch, have been restored and now welcome visitors.
Tribal artifact at the Museum of Western Colorado.
Nowitz Photography/Apa Publications