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Front Range

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Pikes Peak and Garden of the Gods.
Front Range near Estes Park, Colorado.

The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the north-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 moving west 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 up to more than 9,000 feet above the Great Plains. Longs Peak, Mount Evans, 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.

Geology

Pikes Peak Granite

About 1 billion years ago, the earth was producing mass amounts of molten rock that would one day amalgamate, drift together and combine, to ultimately form the continents we live on today. In the Colorado region, this molten rock spewed and cooled, forming what we now know as the Precambrian Pikes Peak Granite. Over the next 500 million years, little is known about changes in the sedimentation (sediment deposition) after the granite was produced. However, 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]

Fountain formation

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 uplift the mountains would continue to erode and cover themselves 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 end. The sediment from these once gigantic mountains lies in the Fountain Formation today. Red Rocks Amphitheater outside of Denver, Colorado, is actually set into the Fountain Formation.[2]

Lyons Sandstone

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]

Lykins Formation

30 million years later, the sediment deposition was still taking place with the introduction of the Lykins Formation. This formation can be best attributed to its wavy layers of muddy limestone and signs of stromatolites that thrived in a smelly tidal flat at present-day Colorado. 250 million years ago, the Ancestral Rockies were burying themselves 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 was destroyed and a great deal on land as well.[2]

Morrison Formation

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]

Dakota Sandstone

The Dakota Sandstone, which was deposited 100 million years ago towards Colorado’s eastern coast, shows evidence of ferns, and dinosaur tracks. Sheets of ripple marks can be seen on some of the strata, confirming the shallow-sea environment.[2]

Pierre Shale

Over the next 30 million years, the region was finally taken over the by a deep sea, the Cretaceous Western Interior Seaway, and deposited mass amounts of shale over the area known as the Pierre Shale. Both the thick section of shale and the marine life fossils found (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). Colorado eventually drained from being at the bottom of an ocean to land again, giving yield to another fossiliferous rock layer, the Denver Formation. At about 68 million years ago, the Front Range began to rise again due to the Laramide Orogeny in the west.[2]

Denver Formation

The Denver Formation contained fossils and bones from 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 K–T boundary. In an instant, millions of species are obliterated from a meteor impact in Mexico’s Yucatan Peninsula. While this extinction lead to the dinosaurs’ and other organisms’ demise, some life did prevail to repopulate the earth as it recovered from this tremendous disaster. The uplifted Front Range continued to constantly erode and, by 40 million years ago, the range was once again buried in its own rubble.[2]

Castle Rock Conglomerate

Suddenly, 37 million years ago, a great volcanic eruption took place in the Collegiate Range and covered the landscape in molten 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 gave way to the Castle Rock Conglomerate that can be found in the Front Range.[2]

Quaternary deposits

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 as viewed from Greenwood Village south of Denver, Mount Evans is on the far right

Prominent peaks

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 Evans, Longs Peak, Pikes Peak, and Mount Bierstadt.

Longs Peak
The 20 Mountain Peaks of the Front Range With At Least 500 Meters of Topographic Prominence
Rank Mountain Peak Subrange Elevation Prominence Isolation
1 Grays Peak[3] NGS Front Range 4352 m
14,278 ft		 844 m
2,770 ft		 40.3 km
25 mi
2 Mount Evans NGS Front Range 4348 m
14,265 ft		 844 m
2,769 ft		 15.76 km
9.79 mi
3 Longs Peak NGS Front Range 4346 m
14,259 ft		 896 m
2,940 ft		 70.2 km
43.6 mi
4 Pikes Peak NGS Pikes Peak Massif 4302 m
14,115 ft		 1686 m
5,530 ft		 97.8 km
60.8 mi
5 Mount Silverheels NGS PB Front Range 4215 m
13,829 ft		 696 m
2,283 ft		 8.82 km
5.48 mi
6 Bald Mountain[4] PB Front Range 4173 m
13,690 ft		 640 m
2,099 ft		 12.09 km
7.51 mi
7 Bard Peak[4] PB Front Range 4159 m
13,647 ft		 518 m
1,701 ft		 8.74 km
5.43 mi
8 Hagues Peak NGS PB Mummy Range 4137 m
13,573 ft		 738 m
2,420 ft		 25.6 km
15.92 mi
9 North Arapaho Peak[4] PB Indian Peaks PB 4117 m
13,508 ft		 507 m
1,665 ft		 24.8 km
15.4 mi
10 Parry Peak[4] Front Range 4083 m
13,397 ft		 528 m
1,731 ft		 15.22 km
9.46 mi
11 Mount Richthofen[4] PB Front Range 3946 m
12,945 ft		 817 m
2,680 ft		 15.54 km
9.66 mi
12 Specimen Mountain[4] PB Front Range 3808 m
12,494 ft		 528 m
1,731 ft		 7.82 km
4.86 mi
13 Bison Peak NGS PB Tarryall Mountains PB 3789 m
12,432 ft		 747 m
2,451 ft		 30.8 km
19.14 mi
14 Waugh Mountain[4] PB South Park Hills PB 3571 m
11,716 ft		 710 m
2,330 ft		 32.2 km
20 mi
15 Black Mountain NGS PB South Park Hills PB 3551 m
11,649 ft		 681 m
2,234 ft		 12.92 km
8.03 mi
16 Williams Peak NGS PB South Williams Fork Mountains PB 3542 m
11,620 ft		 625 m
2,049 ft		 17.37 km
10.79 mi
17 Puma Peak[4] PB South Park Hills PB 3528 m
11,575 ft		 689 m
2,260 ft		 11.97 km
7.44 mi
18 Thirtynine Mile Mountain[4] PB South Park Hills PB 3521 m
11,553 ft		 636 m
2,088 ft		 17.08 km
10.61 mi
19 Twin Sisters Peaks[4] PB Front Range 3485 m
11,433 ft		 710 m
2,328 ft		 7.01 km
4.36 mi
20 South Bald Mountain [1] Laramie Mountains 3355 m
11,007 ft		 562 m
1,844 ft		 22 km
13.66 mi
The Front Range as viewed from Tower Road east of Denver, Mount Evans is shown in the center

See also

References

  1. ^ http://geonames.usgs.gov/pls/gnispublic | U.S. Geological Survey confirms that the Laramie Mountains(range) are the northern extent of the Front Range.
  2. ^ a b c d e f g h i j k l m Johnson, Kirk R.; et al. (2006). Ancient Denvers. Fulcrum Publishing. ISBN 978-1555915544. {{cite book}}: Explicit use of et al. in: |first= (help)
  3. ^ The summit of Grays Peak is the highest point on the Continental Divide of North America.
  4. ^ a b c d e f g h i j The elevation of this summit has been converted from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the North American Vertical Datum of 1988 (NAVD 88). National Geodetic Survey

Further reading

  • Fishman, N.S. et al. (2005). Principal areas of oil, natural gas, and coal production in the northern part of the Front Range, Colorado [Geologic Investigations Series I-2750-B]. Reston, VA: U.S. Department of the Interior, U.S. Geological Survey.
  • Sprague, L.A., R.E. Zuellig, and J.A. Dupree. (2006). Effects of urban development on stream ecosystems along the Front Range of the Rocky Mountains, Colorado and Wyoming [USGS Fact Sheet 2006-3083]. Reston, VA: U.S. Department of the Interior, U.S. Geological Survey.
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