Front Range | |
---|---|
Highest point | |
Peak | Grays Peak |
Elevation | 14,278 ft (4,352 m) |
Coordinates | 39°38′02″N105°49′01″W / 39.63389°N 105.81694°W |
Geography | |
The Front Range (excluding the Laramie Mountains) is shown highlighted on a map of the western U.S. | |
Country | United States |
States |
|
Parent range | Rocky Mountains |
The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the central portion of the U.S. State of Colorado, and southeastern portion of the U.S. State of Wyoming. [1] It is the first mountain range encountered as one goes westbound along the 40th parallel north across the Great Plains of North America.
The Front Range runs north-south between Casper, Wyoming, and Pueblo, Colorado, and rises nearly 10,000 feet above the Great Plains. Longs Peak, Mount Blue Sky, and Pikes Peak are its most prominent peaks, visible from the Interstate 25 corridor. The area is a popular destination for mountain biking, hiking, climbing, and camping during the warmer months and for skiing and snowboarding during winter. Millions of years ago, the present-day Front Range was home to ancient mountain ranges, deserts, beaches, and even oceans. [2]
The name "Front Range" is also applied to the Front Range urban corridor, the populated region of Colorado and Wyoming just east of the mountain range and extending from Cheyenne, Wyoming south to Pueblo, Colorado. This urban corridor benefits from the weather-moderating effect of the Front Range mountains, which help block prevailing storms.
About 1 billion years ago, a mass of magma rose to the surface through a much older mantle, cooling to form what is now known as the Precambrian Pikes Peak Granite. Over the next 500 million years, the granite eroded with no sedimentation forming over this first uplift, resulting in a local expression of the Great Unconformity. At about 500–300 million years ago, the region began to sink and sediments began to deposit in the newly formed accommodation space. Eroded granite produced sand particles that began to form strata, layers of sediment, in the sinking basin. Sedimentation would continue to take place until about 300 million years ago. [2] [3]
Around 300 million years ago, the sinking suddenly reversed, and the sediment-covered granite began to uplift, giving rise to the Ancestral Rocky Mountains. Over the next 150 million years, during the uplift the mountains continued to erode and cover their flanks in their own sediment. Wind, gravity, rainwater, snow, and ice-melt supplied rivers that ultimately carved through the granite mountains and eventually led to their complete removal. The sediment from these mountains lies in the very red Fountain Formation today. Red Rocks Amphitheatre outside of Denver, Colorado, is set within the Fountain Formation. [2]
At 280 million years ago, sea levels were low and present-day Colorado was part of the super-continent Pangaea. Sand deserts covered most of the area, spreading as dunes seen in the rock record, known today as the Lyons Sandstone. These dunes appear to be cross-bedded and show various fossil footprints and leaf imprints in many of the strata making up the section. [2] Uplifted beds of Lyons Sandstone are found along the Front range and form the gateway to the Garden of the Gods. [3]
30 million years later, the sediment deposition was still taking place with the introduction of the Lykins Shale. This formation can be best attributed to its wavy layers of muddy limestone and signs of stromatolites that thrived in a tidal flat in present-day Colorado. 250 million years ago, the Ancestral Rockies were eroding away [3] while the shoreline was present during the break-up of Pangaea. This formation began right after Earth's largest extinction 251 million years ago at the Permian–Triassic Boundary. Ninety percent of the planet's marine life became extinct and a great deal on land as well. [2]
After 100 million years of deposition, a new environment brought rise to a new formation, the sandstone Morrison Formation. The Morrison Formation contains some of the best fossils of the Late Jurassic. It is especially known for its sauropod tracks and sauropod bones, among other dinosaur fossils. As identified by the fossil record, the environment was filled with various types of vegetation such as ferns and Zamites . [2] While this time period boasts many types of plants, grass had not yet evolved. [2]
The Dakota Sandstone, which was deposited around 100 million years ago at the opening of the Cretaceous Western Interior Seaway from the Arctic to the Tropics, shows evidence of ferns and dinosaur tracks. Sheets of ripple marks can be seen on some of the strata, confirming advancing and retreating near-shore environments. [2] These Dakota Group sandstone beds are resistant to erosion and have uplifted to form the Dakota Hogback, a ridge between the mountains and the plains. [3]
Over the next 35 million years, the Cretaceous seaway repeatedly widened as far as Utah and Wisconsin and narrowed to near closure. [4] With no mountains present at the time, the Colorado area was in the line of the deepest channel of the seaway; but being on the Transcontinental Arch, the Front Range areas was relatively shallow and was near the last land to submerge as the seaway opened. Shale and chalk were deposited over the area as Greenhorn of the Benton Group and the Niobrara Formation. Within these beds are found abundant marine fossils (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. Today, the Fort Hays Limestone member forms flatirons or secondary hogbacks on the east slope of the Dakota Hogback. [5]
The non-chalky shales of the Pierre Formation formed in the final cycle of the seaway. At about 68 million years ago, the Front Range began to rise again due to the Laramide Orogeny in the western half of the state, draining from being at the bottom of a sea to land again, giving yield to another fossiliferous rock layer, the Denver Formation. [2]
The Denver Formation contains fossils of dinosaurs like Tyrannosaurus rex and Triceratops. While the forests of vegetation, dinosaurs, and other organisms thrived, their reign would come to an end at the Cretaceous–Paleogene boundary (which was formerly known as the K-T boundary). In an instant, millions of species were obliterated by a meteor impact in Mexico's Yucatán Peninsula. While this extinction led to the demise of the dinosaurs and other organisms, some life did prevail to repopulate the earth as it recovered from this tremendous disaster. The uplifted mountains continued to constantly erode and, by 40 million years ago, the region was once again buried in material eroded from the central mountains. [2]
Suddenly, 37 million years ago, a great volcanic eruption took place in the Collegiate Range and covered the landscape in hot ash that instantly torched and consumed everything across the landscape. An entire lush environment was capped in a matter of minutes with 20 feet of extremely resistant rock, rhyolite. However, as seen before, life rebounds, and after a few million years mass floods cut through the rhyolite and eroded much of it as plants and animals began to recolonize the landscape. The mass flooding and erosion of the volcanic rock formed the Castle Rock Conglomerate that can be found in the Front Range. [2]
Eventually, at about 10 million years ago, the Front Range began to rise up again and the resistant granite in the heart of the mountains thrust upwards and stood tall, while the weaker sediments deposited above it eroded away. As the Front Range rose, streams and recent (16,000 years ago) glaciations during the Quaternary age literally unburied the range by cutting through the weaker sediment and giving rise to the granitic peaks present today. [2] This was the last step in forming the present-day geologic sequence and history of today's Front Range. [2]
The Front Range includes the highest peaks along the eastern edge of the Rockies. The highest mountain peak in the Front Range is Grays Peak. Other notable mountains include Torreys Peak, Mount Blue Sky, Longs Peak, Pikes Peak, and Mount Bierstadt.
Rank | Mountain Peak | Subrange | Elevation | Prominence | Isolation |
---|---|---|---|---|---|
1 | Grays Peak [6] NGS | Front Range | 14,278 ft 4352 m | 2,770 ft 844 m | 25 mi 40.3 km |
2 | Mount Blue Sky NGS | Front Range | 14,265 ft 4348 m | 2,769 ft 844 m | 9.79 mi 15.76 km |
3 | Longs Peak NGS | Front Range | 14,259 ft 4346 m | 2,940 ft 896 m | 43.6 mi 70.2 km |
4 | Pikes Peak NGS | Pikes Peak Massif | 14,115 ft 4302 m | 5,530 ft 1686 m | 60.8 mi 97.8 km |
5 | Mount Silverheels NGS PB | Front Range | 13,829 ft 4215 m | 2,283 ft 696 m | 5.48 mi 8.82 km |
6 | Bald Mountain [7] PB | Front Range | 13,690 ft 4173 m | 2,099 ft 640 m | 7.51 mi 12.09 km |
7 | Bard Peak [7] PB | Front Range | 13,647 ft 4159 m | 1,701 ft 518 m | 5.43 mi 8.74 km |
8 | Hagues Peak NGS PB | Mummy Range | 13,573 ft 4137 m | 2,420 ft 738 m | 15.92 mi 25.6 km |
9 | North Arapaho Peak [7] PB | Indian Peaks PB | 13,508 ft 4117 m | 1,665 ft 507 m | 15.4 mi 24.8 km |
10 | Parry Peak [7] | Front Range | 13,397 ft 4083 m | 1,731 ft 528 m | 9.46 mi 15.22 km |
11 | Mount Richthofen [7] PB | Front Range | 12,945 ft 3946 m | 2,680 ft 817 m | 9.66 mi 15.54 km |
12 | Specimen Mountain [7] PB | Front Range | 12,494 ft 3808 m | 1,731 ft 528 m | 4.86 mi 7.82 km |
13 | Bison Peak NGS PB | Tarryall Mountains PB | 12,432 ft 3789 m | 2,451 ft 747 m | 19.14 mi 30.8 km |
14 | Waugh Mountain [7] PB | South Park Hills PB | 11,716 ft 3571 m | 2,330 ft 710 m | 20 mi 32.2 km |
15 | Black Mountain NGS PB | South Park Hills PB | 11,649 ft 3551 m | 2,234 ft 681 m | 8.03 mi 12.92 km |
16 | Williams Peak NGS PB | South Williams Fork Mountains PB | 11,620 ft 3542 m | 2,049 ft 625 m | 10.79 mi 17.37 km |
17 | Puma Peak [7] PB | South Park Hills PB | 11,575 ft 3528 m | 2,260 ft 689 m | 7.44 mi 11.97 km |
18 | Thirtynine Mile Mountain [7] PB | South Park Hills PB | 11,553 ft 3521 m | 2,088 ft 636 m | 10.61 mi 17.08 km |
19 | Twin Sisters Peaks [7] PB | Front Range | 11,433 ft 3485 m | 2,328 ft 710 m | 4.36 mi 7.01 km |
20 | South Bald Mountain | Laramie Mountains | 11,007 ft 3355 m | 1,844 ft 562 m | 13.66 mi 22 km |
The main interstate highways that run through the Front Range are Interstate 70, which crosses west of Denver, Colorado, and Interstate 80, which crosses near Laramie, Wyoming. U.S. Route 34 travels through the mountains near Loveland, Colorado, although this route is typically closed from October to May. [8] U.S. Route 24 travels through the southern Front Range west of Colorado Springs, eventually connecting with I-70 west of Vail, Colorado.
Along with the roads that run through the Front Range, the Union Pacific Railroad operates two rail lines through the mountains. The first Overland Route, transiting southern Wyoming, runs parallel to I-80 for much of its way. The second is the former Denver & Rio Grande Western Railroad Moffat Route, which runs parallel to the Colorado River and through the 6.5-mile-long Moffat Tunnel. Originally the Denver and Salt Lake Railway, the former Rio Grande is used for freight by both Union Pacific and BNSF, and it is also used by Amtrak's California Zephyr and Winter Park Express .
The geology of the Grand Canyon area includes one of the most complete and studied sequences of rock on Earth. The nearly 40 major sedimentary rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from about 200 million to nearly 2 billion years old. Most were deposited in warm, shallow seas and near ancient, long-gone sea shores in western North America. Both marine and terrestrial sediments are represented, including lithified sand dunes from an extinct desert. There are at least 14 known unconformities in the geologic record found in the Grand Canyon.
The exposed geology of the Bryce Canyon area in Utah shows a record of deposition that covers the last part of the Cretaceous Period and the first half of the Cenozoic era in that part of North America. The ancient depositional environment of the region around what is now Bryce Canyon National Park varied from the warm shallow sea in which the Dakota Sandstone and the Tropic Shale were deposited to the cool streams and lakes that contributed sediment to the colorful Claron Formation that dominates the park's amphitheaters.
The geology of the Grand Teton area consists of some of the oldest rocks and one of the youngest mountain ranges in North America. The Teton Range, partly located in Grand Teton National Park, started to grow some 9 million years ago. An older feature, Jackson Hole, is a basin that sits aside the range.
The geology of the park is the consequence of deposition, uplift and erosion. Island in the Sky is a mesa overlooking the Green River to the west and the Colorado River to the east, and separated from the Colorado Plateau by the "the neck". From the top of the mesa to the Honaker Trail Formation at the canyon river bottom, 150 million years of geologic stratum is exposed. Upheaval Dome consists of the Chinle Formation in the center and the Navajo Sandstone along the rim. The Cedar Mesa Sandstone comprised the Needles District. Canyons comprise the Maze District.
The exposed geology of the Capitol Reef area presents a record of mostly Mesozoic-aged sedimentation in an area of North America in and around Capitol Reef National Park, on the Colorado Plateau in southeastern Utah.
The Denver Basin, variously referred to as the Julesburg Basin, Denver-Julesburg Basin, or the D-J Basin, is a geologic structural basin centered in eastern Colorado in the United States, but extending into southeast Wyoming, western Nebraska, and western Kansas. It underlies the Denver-Aurora Metropolitan Area on the eastern side of the Rocky Mountains.
The Dakota Hogback is a long hogback ridge at the eastern fringe of the Rocky Mountains that extends north-south from southern Wyoming through Colorado and into northern New Mexico in the United States. The ridge is prominently visible as the first line of foothills along the edge of the Great Plains. It is generally faulted along its western side, and varies in height, with gaps in numerous locations where rivers exit the mountains. The ridge takes its name from the Dakota Formation, a formation with resistant sandstone beds that cap the ridge. The hogback was formed during the Laramide orogeny, approximately 50 million years ago, when the modern Rockies were created. The general uplift to the west created long faulting in the North American Plate, resulting in the creation of the hogback.
Pikes Peak granite is a 1.08 billion year old Late-Precambrian geologic formation found in the central part of the Front Range of Colorado. It is a coarse-grained pink to light red syenogranite with minor gray monzogranite, and it has a distinctive brick-red appearance where it outcrops. The granite gets its name from the 14,115-foot (4,302 m) Pikes Peak, which is made up almost entirely of this rock.
The geology of the Rocky Mountains is that of a discontinuous series of mountain ranges with distinct geological origins. Collectively these make up the Rocky Mountains, a mountain system that stretches from Northern British Columbia through central New Mexico and which is part of the great mountain system known as the North American Cordillera.
The Fountain Formation is a Pennsylvanian bedrock unit consisting primarily of conglomerate, sandstone, or arkose, in the states of Colorado and Wyoming in the United States, along the east side of the Front Range of the Rocky Mountains, and along the west edge of the Denver Basin.
In geology and geomorphology, a hogback or hog's back is a long, narrow ridge or a series of hills with a narrow crest and steep slopes of nearly equal inclination on both flanks. Typically, the term is restricted to a ridge created by the differential erosion of outcropping, steeply dipping, homoclinal, and typically sedimentary strata. One side of a hogback consists of the surface of a steeply dipping rock stratum called a dip slope. The other side is an erosion face that cuts through the dipping strata that comprises the hogback. The name "hogback" comes from the Hog's Back of the North Downs in Surrey, England, which refers to the landform's resemblance in outline to the back of a hog. The term is also sometimes applied to drumlins and, in Maine, to both eskers and ridges known as "horsebacks".
The Laramie Formation is a geologic formation of the Late Cretaceous (Maastrichtian) age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States. It was deposited on a coastal plain and in coastal swamps that flanked the Western Interior Seaway. It contains coal, clay and uranium deposits, as well as plant and animal fossils, including dinosaur remains.
The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Interior Seaway. The usage of the name Dakota for this particular Albian-Cenomanian strata is exceptionally widespread; from British Columbia and Alberta to Montana and Wisconsin to Colorado and Kansas to Utah and Arizona. It is famous for producing massive colorful rock formations in the Rocky Mountains and the Great Plains of the United States, and for preserving both dinosaur footprints and early deciduous tree leaves.
Dinosaur Ridge is a segment of the Dakota Hogback in the Morrison Fossil Area National Natural Landmark located in Jefferson County, Colorado, near the town of Morrison and just west of Denver.
Prehistory of Colorado provides an overview of the activities that occurred prior to Colorado's recorded history. Colorado experienced cataclysmic geological events over billions of years, which shaped the land and resulted in diverse ecosystems. The ecosystems included several ice ages, tropical oceans, and a massive volcanic eruption. Then, ancient layers of earth rose to become the Rocky Mountains.
The Arapahoe Formation is a geological formation of latest Cretaceous (Maastrichtian) age that is present within the Denver Basin that underlies the Denver, Colorado, area. The formation includes fossil leaves and dinosaur remains, although none of the latter have yet been referred to a specific genus. It also includes aquifers that are important sources of water for the area.
The geology of Wyoming includes some of the oldest Archean rocks in North America, overlain by thick marine and terrestrial sediments formed during the Paleozoic, Mesozoic and Cenozoic, including oil, gas and coal deposits. Throughout its geologic history, Wyoming has been uplifted several times during the formation of the Rocky Mountains, which produced complicated faulting that traps hydrocarbons.
The geology of Utah, in the western United States, includes rocks formed at the edge of the proto-North American continent during the Precambrian. A shallow marine sedimentary environment covered the region for much of the Paleozoic and Mesozoic, followed by dryland conditions, volcanism, and the formation of the basin and range terrain in the Cenozoic.
The bedrock under the U.S. State of Colorado was assembled from island arcs accreted onto the edge of the ancient Wyoming Craton. The Sonoma orogeny uplifted the ancestral Rocky Mountains in parallel with the diversification of multicellular life. Shallow seas covered the regions, followed by the uplift current Rocky Mountains and intense volcanic activity. Colorado has thick sedimentary sequences with oil, gas and coal deposits, as well as base metals and other minerals.
The Lytle Formation or Lytle Sandstone is a geologic formation found in Wyoming, Colorado, and New Mexico.