Located in Southwestern Colorado, the Gunnison National Park is best known for the narrow gorge called the Black Canyon. With a depth that reaches 2,700 feet (820 meters), the canyon was carved by thousands of years of erosion by the Gunnison River. Scenic overlooks along the 6-mile (10 km) South Rim Road offer views of the canyon. The Cedar Point Nature Trail off South Rim is an easy-to-navigate hiking trail that includes signs about the area’s plants. It leads to a great view of the 2,250 foot (7,380) high Painted Wall, the tallest cliff in the state.
Located one mile from the main entrance of Rocky Mountain National Park and two miles from Estes Park, Rams Horn Village Resort offers 46 luxury cabins, a heated outdoor swimming pool in the summer, three outdoor, year-round hot tubs, a fitness center and a playground on over seven acres of landscaped grounds. Every amenity at Rams Horn is free to use with your reservation and every cabin will turn into a second home.
In the winter, Steamboat Springs is famous for its champagne powder; in the summertime the Yampa River Valley, Steamboat Lake and Zirkel Wilderness Area become a veritable outdoor wonderland with boat rentals, canoeing, kayaking, fishing, SUP, swimming and camping. The Coca Cola Adventure Zone at the base of Steamboat Ski Resort includes ropes course, slingshot bungee jump, climbing wall, mini-bounce, mechanical bull, human gyro and t-shirt spin art. Bring your bikes and wind along the paved four-mile Yampa River Core Trail that follows the Yampa River. Or better yet, grab a tube and cruise down the only free-flowing river in the state, meaning that nowhere along its 261 miles is it obstructed by dams or diversions (a bonus for those float trips). If you want to warm up (really hot), checkout the natural hot mineral springs at Old Town Hot Springs and Strawberry Park Natural Hot Springs. A not-to-be missed event is Steamboat Springs Pro Rodeo where contestants gather once a week to compete. Once upon a time, my daughter won the Ram Scramble and still raves about it. It’s not every day grabbing a ribbon from a sheep’s rear counts as a win!
The rooms here are Euro-sexy, with dark, thick, exposed beams and spacious, mirror-lined bathrooms. The spa is one of the best in Vail Valley, with a beautiful indoor-outdoor pool, fresh spa water and tea easily accessible and multiple hot tubs, both inside and out. Sit in the bubbling, warm water with a cup of tea while snowflakes drift around you. 
After facing near extinction last century, the bighorn sheep population is currently thriving: there are roughly 300–400 of these striking animals in the park. Look for them at the aptly named Sheep Lakes from May through mid-August, when the bighorns descend to eat soil and obtain minerals not found in their high mountain habitat. Their visits generally occur between 9 a.m. and 3 p.m.
Brian and I descended back to ~7,000 feet for dinner in a small-town Indian restaurant in Nederland, Colorado, west of Boulder. By then, both our heads ached like a bad hangover, and my lungs literally burned when I tried to inhale anything but shallow breaths. Add generalized joint pain, and I had a full-blown case of altitude sickness. Given that I am a noted hypochondriac, I expected the worst.
The Experience: Super close to Manitou Springs, you'll find another town called Colorado Springs, which is also in the Pikes Peak region. While you're there, you have to see the park known as the Garden of the Gods. As its title implies, it's pretty otherworldly. With incredible, oddly shaped sandstone rock formations, you'll want to spend all day here. You should also pay a visit to the Royal Gorge Bridge, an insanely high, dramatic bridge between the canyons. Then head to the upscale resort Broadmoor.
If you love the great outdoors but also want luxurious comfort on your vacation, let the Cabins at Rams Horn Village Resort be basecamp for your Rocky Mountain Getaway. Our western-styled Cabins are the definition of Rocky Mountain comfort w/ all the modern conveniences.  Each cabin is its own private retreat from everyday cares, allowing families & friends to come & play together, & build lifelong memories.  Rams Horn Village Resort Details
Home to the Steamboat ski resort, Steamboat Springs is a city in Colorado’s Yampa Valley. One of the main attractions here are the geothermal hot springs, which people come to experience for its healing properties. The Old Town Hot Springs also has water slides and swimming pools, while the ski resort has six peaks including Mount Werner for the serious snowboarding and skiing enthusiast.
Dial (970) 586-1222 for a recorded message on the status of Trail Ridge Road. You may not know that our mountain makes its own weather, so it is not uncommon to have snow in July or August at the top of Trail Ridge Road. Such weather will only last for a few hours to a day, but if you are planning to cross over Trail Ridge Road, weather may hamper your travel. You also may find the road closed due to weather in early June and September/October.
Telluride offers the quintessential Colorado mountain town experience. Not only are its streets lined with grand Victorian buildings, but it has become a hub for adventurers, athletes, and artists of all types, nestled in an isolated box canyon, far from the chaos of modern life. While there’s no skiing this time of year, visitors can still take a ride on the gondola up the mountain to get a bird’s eye view of the town and the breathtaking surrounding landscape. There’s also the opportunity to hike to the state’s longest free-falling waterfall, Bridal Veil Falls, enjoy fantastic fishing, golfing and biking. This little town is big when it comes to festivals too, with the annual Bluegrass Festival bringing a multitude of bluegrass bands to the area to enjoy the sun and the tunes in the outdoor amphitheater.

It’s hard to beat the majestic setting at The Peaks Resort & Spa in Telluride. This property is surrounded by the dramatic peaks of the Rockies in the southwestern region of the state, and is particularly renowned for its spa. Here you can indulge in a variety of rejuvenating treatments like hot stone therapy, soak in the eucalyptus-filled Jacuzzis or take advantage of personal training sessions. Enjoy your days taking part in outdoor adventures like mountain biking or hiking the spectacular trails and then come back to enjoy a
The Experience: Like Crested Butte, Telluride is a place that anyone will fall in love with no matter the season. Plus, it's a bit more down-to-earth than Aspen and Vail for anyone looking for a Colorado ski town that has a more casual energy. Surrounded by the San Juan Mountains, the charming town is lined with authentic saloon-like bars, boutique gourmet eateries, and old-school chop houses. If you visit during the winter, hit the slopes or go helicopter skiing and dog sledding. And in the summer, you can do anything from riding around the backcountry in an old Jeep to river rafting, fly-fishing, and hiking to the many striking mountain springs, including Blue Lakes, Hope Lake, and Navajo Lake. Book a room at the Dunton Town House for an intimate stay.
If you are looking for romantic mountain getaways in Colorado, Taharaa Mountain Lodge in Estes Park, Colorado is a beautiful country lodge just minutes from the Rocky Mountain National Park. Set on five acres, the lodge offers vacationers nine rooms and nine suites with stunning views of the surrounding mountains. Guest room decor incorporates natural elements from the region. Each room and suite has floor-to-ceiling windows, fireplace and a panoramic outdoor deck, perfect for savoring the view. Ask for one of the suites with a Jacuzzi tub if you are planning a romantic getaway or a honeymoon in Colorado. The lodge has a sauna and a cozy massage room where guests can enjoy a variety of treatments, such as aromatherapy, hot stone massage and facials. Rooms start at $159 per night. Delicious morning breakfast and evening happy hour are included in the cost of your stay.
Ready to get romantic?  Stop in and enjoy the Armstrong’s on-site speakeasy-era jazz club,  Ace Gillett’s Lounge, located in the basement of the Armstrong Hotel. An underground shadowy enclave with nearly 100 years of history, order from their signature drink of martinis, wine and local brews, and kick back with your sweetheart in two cozy rooms featuring live jazz music 4 nights a week.

The Fall River Visitor Center just outside Rocky Mountain National Park is the only one open during the government shutdown. It's run by the Rocky Mountain Conservancy, a non-profit that supports the park. That, plus its location outside the park, and the fact that the Rocky Mountain Conservancy leases the private building are why this visitor center can stay open.
The climate change study projects further temperature increases, with greater warming in the summer and higher extreme temperatures by 2050. Due to the increased temperature, there is a projected moderate increase in the rate of water evaporation. Reduced snowfall—perhaps 15% to 30% less than current amounts—and the elimination of surface hail, along with the higher likelihood of intense precipitation events are predicted by 2050. Droughts may be more likely due to increased temperatures, increased evaporation rates, and potential changes in precipitation.[53]
The outdoor adventurer remains busy throughout the year in Rocky Mountain National Park. Open 365 days a year, there are activities and sports throughout the summer/fall and winter/spring seasons. Whether looking for a new route to an adrenaline rush, or simply enjoying a favorite pastime, Rocky Mountain National Park's unique and varied landscapes offer something fun. 

Rocky Mountain National ParkAt the edge of Rocky Mountain National Park, Grand Lake is the deepest natural lake in Colorado, dipping to 265 feet. Fed by high mountain runoff, the lake is clear and pristine. In the summer, you can rent a boat, bring your own or simply enjoy the gentle lapping of the waves from the sandy shore. Grand Lake connects with Shadow Mountain Lake via a canal, and just down the road is Lake Granby, the second largest body of water in Colorado.

Fort Collins is just an hour north of Denver, but it offers a ton of fun outdoor things to do when you want to take advantage of the sunshine. Just minutes from downtown is Horsetooth Mountain Open Space, a 2,711-acre park with 29 miles of biking, hiking, and horseback trails just west of Horsetooth Reservoir, which happens to be an ideal spot for paddling out in a canoe or kayak. Mountain Whitewater offers whitewater rafting trips on Cache La Poudre River, which flows right through downtown, while the Farm at Lee Martinez Park is an educational zoo that has animals for feeding and cuddling up with, pony rides, hayrides, and interactive adventures. Beer lovers can tour and taste at a number of outstanding area breweries, or even take a Beer & Bike tour where you can enjoy a variety of beers after a hard day of pedaling.
The riparian ecosystem runs through the montane, subalpine, and alpine tundra zones and creates a foundation for life, especially for species that thrive next to streams, rivers, and lakes.[74] The headwaters of the Colorado River, which provides water to many of the southwestern states, are located on the west side of the park. The Fall River, Cache la Poudre River and Big Thompson Rivers are located on the east side of the park. Just like the other ecosystems in the park, the riparian zone is affected by the climatic variables of temperature, precipitation, and elevation. Generally, riparian zones in valleys will have cooler temperatures than communities located on slopes and ridge tops. Depending on elevation, a riparian zone may have more or less precipitation than other riparian zones in the park, with the difference creating a shift in the types of plants and animals found in a specific zone.[75]
The Trail Ridge Road, which itself reaches an altitude of more than 12,000 feet, is the main driving route through the park and offers easy access to this incredible terrain. You can sightsee from the comfort of your car or stop off along the way for a hike or easy walk. The park has an extensive system of hiking trails that range from paths of less than a half-mile to full-day and multi-day hikes. If you're lucky, you may see elk, bighorn sheep, deer, and other critters.

Become immersed in Rocky’s pristine landscape on some of the park’s 355 miles of hiking trails. Choose from flat lakeside walks to steeper, more challenging mountain climbs. The easy .6-mile Bear Lake trail is a popular hike featuring an interpretive nature trail hugging a subalpine lake at the end of Bear Lake Road. For a stunning waterfall hike, make your way to Alberta Falls or Ouzel Falls.

ItineraryThis is a typical itinerary for this productStop At: Images of Rocky Mountain National Park, Estes Park, ColoradoEnjoy winter in all its beauty and head for the mountains on this incredible 8-hour tour to Rocky Mountain National Park. Around each corner are breathtaking views, alpine lakes and wildlife in a serene setting. Wintertime is the perfect to head to the park as the snow capped mountains are truly breathtaking with the peace and tranquility the mountains have to offer.Duration: 5 hours
Easily accessible from Estes Park is Rocky Mountain National Park, which boasts over 100 mountain peaks that tower over 11,000 feet above the ground. In this gorgeous park, you will find over 300 hiking trails as well as paths to traverse by car or on horseback. Exploring the park will also bring you into close contact with a variety of wildlife, from striped chipmunks to large elk.
The park is home to many predatory animals, including Canadian lynx, foxes, bobcat, cougar, black bear, and coyotes. Wolves and grizzly bears were extirpated in the early 1900s. Most of these predators kill smaller animals, but mountain lions and coyotes kill deer and occasionally elk. Bears also eat larger prey. Moose have no predators in the park. Black bears are relatively uncommon in the park, numbering only 24-35 animals. They also have fewer cubs and the bears seem skinnier than they do in most areas.[79] Canadian lynx are quite rare within the park, and they have probably spread north from the San Juan Mountains, where they were reintroduced in 1999. Cougars feed mainly on mule deer in the park, and live 10–13 years. Cougar territories can be as large as 500 square miles.[80] Coyotes hunt both alone and in pairs, but occasionally hunt in packs. They mainly feed on rodents but occasionally bring down larger animals, including deer, and especially fawns and elk calves. Scat studies in Moraine Park showed that their primary foods were deer and rodents. They form strong family bonds and are very vocal.[81]
A spectacular scenic drive stretches from the old mining town of Silverton, to the town of Ouray, along what is called the Million Dollar Highway. This is a 46-kilometer two-lane highway that hugs the mountainside in places and looks out over jaw-dropping cliffs and across valleys to inspiring mountain peaks. It is one of the most spectacular mountain drives in Colorado. If you have time, you can extend this into a longer route and drive the San Juan Skyway Scenic Byway. The Skyway is a full-day trip that you will want to do in good weather, but can be done in winter or summer.
Perched on the banks of the San Juan River in Pagosa Springs, this hot-springs haven offers a Relaxation Terrace with five pools that are only accessible to the of-age crowd. The terrace is tucked above the kid-friendly main springs area, and includes a waterfall, fire pit, roman shower, jetted tub and river overlook, along with blissful quiet time. Access to the terrace is complimentary for hotel guests and is available to day visitors for a small fee. 
A city that conjures up images of a magical winter wonderland, Aspen boasts beautiful surroundings, where visitors can soak up panoramic views of the Colorado Rockies against the area’s abundance of mountain chalets and popular ski areas. A mecca for winter sports enthusiasts, visitors can also find a wealth of high-end boutiques, interesting museums and excellent hiking trails. Whether you choose to climb to the summit, spot diverse wildlife or simply soak in your surroundings, the Maroon Bell peaks is a must on any itinerary. After a day of adventure at Aspen Mountain, Aspen Highlands or Buttermilk, relax at the world-famous and therapeutic Glenwood Springs.
Breckenridge is justifiably famous as one of the best ski resorts in the country, but spending a little time seeking out the off-piste charms of the town can be extremely rewarding. You can explore the thriving arts and culture scene or learn some Breckenridge history on a tour with a local expert – popular choices include the Historic Tour, the Haunted Tour and the Gold Mining Tour. In summer you can go hiking, biking, fishing, paddling and rafting, while in winter everyone heads to the slopes to enjoy world-class winter sport activities and ride the highest ski lift in the country. Things to Do in Breckenridge

You can climb and slide on the dunes or test your boarding skills cruising down the sand. On hot days, children and even adults enjoy splashing around in the Medano Creek that runs along the base of the dunes. Hiking trails run through the forest on the edge of the dunes. The four-wheel drive Medano Pass Primitive Road opens up some unique terrain, and car camping sites are located along the roadside. Regular camping is available at the Pinon Flats campground, which offers both tent and RV campsites.

Garden of the Gods Park is a registered National Natural Landmark comprised of 1,300 acres of magnificent views and stunning red sandstone formations. TripAdvisor® users voted Garden of the Gods the #1 park in the U.S. and #2 park in the world. Make sure to snap some selfies of you and your partner smooching under Kissing Camels and holding up Balanced Rock.


The ski resort town of Vail is one of the best places to visit in Colorado in winter but it's also a pleasant place to enjoy at any time of year. When it comes to skiing, this is one of the top ski resorts in Colorado, with seemingly endless runs for all levels of skiers. The town at the base of the ski hill is postcard cute, with chalet-style restaurants, shops, and hotels that make you feel like you are in the heart of the Alps. This is a high-end resort with luxury hotels, fine dining, and designer stores.
In the winter, try the “Ski-In/Ski-Out” Treatment—the only one of its kind at a ski resort. In 30 minutes, professionals submerge your feet in a warm, exfoliating bath and go to work to increase circulation. They relieve the tension with a hot stone massage to get you back into action. This treatment is designed perfectly to soothe you after a day of adrenaline and activity, and vamp you back up for more.
Located in southwestern Colorado, close to the Four Corners Monument where Colorado, New Mexico, Arizona and Utah meet, Durango is perfectly positioned for sightseeing and year-round outdoor activities. The town also has a vibrant art scene and you can spend many happy hours visiting a fascinating array of art galleries and live theater attractions.
Getting to Ouray is a spectacular adventure in itself, especially if you take the Million Dollar Highway that follows a 25-mile stretch of US 550 from Silverton to get here. The road’s endless twists and turns, many at the edge of sheer cliffs, brings some of the most jaw-dropping vistas in the world. As you turn each corner, the views of the soaring, jagged peaks of the San Juan Mountains seem to keep getting better – providing a pretty big clue as to why Ouray is often called the “Switzerland of America.” It’s an ideal spot for soaking in natural hot springs, gazing at countless waterfalls, and even exploring old mines.  For an in-depth knowledge of the town’s gold and silver history, head to Bachelor-Syracuse Mine where you’ll find out what it was like to be a miner back in the day. There are also lots of interesting shops on the main street, historic walking tours and even a ghost tour if you’re brave enough.
Stay up past your (kids’) bedtime at this grown-ups-only urban retreat that fuses art and sustainability. Side-by-side Victorian homes sit on the edge of downtown Denver, putting you close to the city’s vibrant dining and nightlife. Many rooms feature murals or paintings by local artists, so you can soak up some culture from your in-room whirlpool tub. There are eco-friendly perks throughout, like organic toiletries and gardens where the onsite chef grows herbs and veggies for your complimentary breakfast.

This 5-bedroom residence features a stunning family room with a massive gas fireplace and a professional chef’s kitchen with dining area and breakfast nook. No expense was spared on the multi-zone sound system and other electronics throughout the home. Guests can settle into the cozy library/TV room or be blown away by the mineshaft themed cinema with a state-of-the-art digital projector and 11.1-point channel sound and hundreds of first-run movies and TV – all complimentary!


After facing near extinction last century, the bighorn sheep population is currently thriving: there are roughly 300–400 of these striking animals in the park. Look for them at the aptly named Sheep Lakes from May through mid-August, when the bighorns descend to eat soil and obtain minerals not found in their high mountain habitat. Their visits generally occur between 9 a.m. and 3 p.m.
Home to the Steamboat ski resort, Steamboat Springs is a city in Colorado’s Yampa Valley. One of the main attractions here are the geothermal hot springs, which people come to experience for its healing properties. The Old Town Hot Springs also has water slides and swimming pools, while the ski resort has six peaks including Mount Werner for the serious snowboarding and skiing enthusiast.
The Olives Aspen restaurant, run by Chef Todd English, serves Mediterranean-inspired cuisine with a local flare. The Lobby Lounge features beautiful views, and offers a light menu with cocktails, aperitifs, wines, and beers. Doubles from $725 per night. The hotel is located 10 minutes from the Airport. You can contact the hotel to arrange transportation. Doubles from $725 per night. The hotel is located 10 minutes from the Airport.
You’ll feel really spoiled (especially in Vail!) with complimentary WiFi,  complimentary underground valet parking, free breakfast buffet included a surprisingly hefty selection of pastries, breads, fruits, meats, cheeses, cold cereals, and eggs, as well as juice, tea, and coffee. And the outdoor heated swimming pool is worth taking the plunge just for the view.
If you love the great outdoors but also want luxurious comfort on your vacation, let the Cabins at Rams Horn Village Resort be basecamp for your Rocky Mountain Getaway. Our western-styled Cabins are the definition of Rocky Mountain comfort w/ all the modern conveniences.  Each cabin is its own private retreat from everyday cares, allowing families & friends to come & play together, & build lifelong memories.  Rams Horn Village Resort Details
Depending on when you choose to stay in an Estes Park vacation rental, you may be able to catch family-friendly events like the annual Teddy Bear Picnic or Longs Peak Scottish-Irish Highland Festival. If you aren't able to make it to those events, don't worry: you can always pick up some local history at the Lula W. Dorsey Museum or Stanley Steam Car Museum. Visit the local shops and galleries like the Wild Spirits Gallery or Alpenglow Images & Accents to see some local photography, woodworking, jewelry, and other crafts or pick up a souvenir or two for friends and family back home. 

Experience diverse ecosystems during your visit to Estes Park, your jumping-off point for Rocky Mountain National Park, which offers many things to do, from guided tours and camping to hikes and stargazing. It’s a great place for solo travelers, as well as families and those traveling with larger groups. Fun activities available include mountain biking, kayaking, going horseback riding, as well as miniature golf, rodeos and amusement parks, to name a few.


Take the world’s largest outdoor mineral hot springs pool (Glenwood Hot Springs), add an adventure park built on top of a mountain (Glenwood Caverns Adventure Park), sprinkle in the Roaring Fork Valley’s crimson rocks and emerald forests and you have a memorable family vacation just a few hours from Denver. The new Historic Fairy Caves Tour at Glenwood Caverns Adventure Park has sections never opened to the public before, takes 50 minutes and has only 12 stairs (perfect for families with small children than the tour of King’s Row, which has 127 steps each way). Also, don’t miss the adventure park’s thrill rides including the Cliff Hanger Roller Coaster, bungee jumping station, zipling, giant canyon swing, alpine coaster, laser tag and much more. Glenwood Hot Springs is celebrating its 125th birthday this year, so guests get in free on their birthdays. Glenwood Canyon Resort has white water rafting on the Colorado River and for an extra thrill, soar on the zipline across the river or test your mettle on a ropes course. Grab your bikes and take the paved Rio Grande Trail, which winds along the Roaring Fork River from Glenwood to Aspen. If you visit mid-week, pack a picnic and enjoy free concerts at Two Rivers Park on Wednesday. For a night out on the town, your family will love the Glenwood Vaudeville Revue dinner variety show.
Colorado's scenic terrain draws millions of travelers looking to get swept up in its natural splendor. With a bevy of cities and towns, each with its own unique outdoor offerings, cultural attractions and general Colorado charm, it may be difficult to choose the best place for your next vacation. U.S. News took into account a number of factors, including the variety of attractions as well as the opinions of experts and travelers, to determine the Best Places to Visit in Colorado. Got a favorite? Cast your vote to help determine next year's list. 
Categories: IUCN Category IIRocky Mountain National ParkRocky MountainsHistory of the Rocky MountainsArchaeological sites in ColoradoBiosphere reserves of the United StatesCivilian Conservation Corps in ColoradoNational parks in ColoradoNational parks of the Rocky MountainsProtected areas established in 1915Protected areas of Boulder County, ColoradoProtected areas of Grand County, ColoradoProtected areas of Larimer County, ColoradoProtected areas on the Colorado River1915 establishments in Colorado
Nothing is more quintessentially Colorado than the city of Golden, which is known for two things: outdoor activities and beer. Your travel plans practically write themselves—go to Lookout Mountain or White Ranch Park for hiking and biking, and then tour the Coors Brewery (the largest single-site brewery in the world) or grab craft beers along with the locals at Golden City Brewery.
Brush up on your Lindy Hop and head to this one-of-a-kind ball that celebrates all things 1940s each June. A hangar at the Boulder Municipal Airport is transformed into a dance hall befitting the USO, with 1940s cars, celebrity impersonators, swing dance lessons, live music and an authentic-attire contest that’ll make you feel like an extra in “Casablanca.” 
The ski resort town of Vail is one of the best places to visit in Colorado in winter but it's also a pleasant place to enjoy at any time of year. When it comes to skiing, this is one of the top ski resorts in Colorado, with seemingly endless runs for all levels of skiers. The town at the base of the ski hill is postcard cute, with chalet-style restaurants, shops, and hotels that make you feel like you are in the heart of the Alps. This is a high-end resort with luxury hotels, fine dining, and designer stores.
Hotel-Scoop.com is a travel resource site with detailed accommodation reviews of lodging worth talking about, from professional globetrotting travel writers. Check in each weekday to see a new review of an interesting hotel, resort, bed and breakfast, or inn - with occasional hotel chatter about hospitality industry trends.. - All Rights Reserved. 
Hot Tubs, Woodstoves, Secluded, Outdoor Fireplace for campfire, WiFi.  Charming, pet friendly, private vacation cabins off Hwy 7 in Allenspark and Raymond, conveniently located between Lyons and Estes Park.  Choose directly on the Middle St Vrain River OR on spacious, wooded acreage bordered by the famous crystal clear Willow Creek.  Year round-Great Value!  Hideout Cabins Details
Precambrian metamorphic rock formed the core of the North American continent during the Precambrian eon 4.5–1 billion years ago. During the Paleozoic era, western North America was submerged beneath a shallow sea, with a seabed composed of limestone and dolomite deposits many kilometers thick.[54] Pikes Peak granite formed during the late Precambrian eon, continuing well into the Paleozoic era, when mass quantities of molten rock flowed, amalgamated, and formed the continents about 1 billion–300 million years ago. Concurrently, in the period from 500–300 million years ago, the region began to sink while lime and mud sediments were deposited in the vacated space. Eroded granite produced sand particles that formed strata—layers of sediment—in the sinking basin.[55]

The Pierre Shale formation was deposited during the Paleogene and Cretaceous periods about 70 million years ago. The region was covered by a deep sea—the Cretaceous Western Interior Seaway—which deposited massive amounts of shale on the seabed. Both the thick stratum of shale and embedded marine life fossils—including ammonites and skeletons of fish and such marine reptiles as mosasaurs, plesiosaurs, and extinct species of sea turtles, along with rare dinosaur and bird remains—were created during this time period. The area now known as Colorado was eventually transformed from being at the bottom of an ocean to dry land again, giving yield to another fossiliferous rock layer known as the Denver Formation.[58]
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