The Full Wiki

Colorado Plateau: Map

  
  
  

Wikipedia article:

Map showing all locations mentioned on Wikipedia article:



The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km² (130,000 mi.²) within western Coloradomarker, northwestern New Mexicomarker, southern and eastern Utahmarker, and northern Arizonamarker. About 90% of the area is drained by the Colorado Rivermarker and its main tributaries; the Green, San Juan and Little Colorado.

In the southwest corner of the Plateau lies the Grand Canyonmarker of the Colorado. Most of the Colorado Plateau's landscape is related, in both appearance and geologic history, to the Grand Canyon. The nickname "Red Rock Country" suggests the brightly colored rock left bare to the view by dryness and erosion. Domes, hoodoos, fins, reefs, goblins, river narrows, natural bridges and slot canyons are only some of the additional features typical of the Plateau.

The Colorado Plateau has the greatest concentration of national parks in the United States. Among its parks are Grand Canyon National Parkmarker, Zion National Parkmarker, Bryce Canyon National Parkmarker, Capitol Reef National Parkmarker, Canyonlands National Parkmarker, Arches National Parkmarker, Mesa Verde National Parkmarker, and Petrified Forest National Parkmarker. Among the national monuments are Dinosaur National Monumentmarker, Hovenweep National Monumentmarker, Wupatki National Monumentmarker, Grand Staircase-Escalante National Monumentmarker, Canyons of the Ancients National Monumentmarker, and Colorado National Monumentmarker.



Geography



The province is bounded by the Rocky Mountains in Colorado, and by the Uinta Mountains and Wasatch Mountains branches of the Rockies in northern and central Utah. It is also bounded by the Rio Grande Rift, Mogollon Rim and the Basin and Range. Isolated ranges of the Southern Rocky Mountains such as the San Juan Mountains in Coloradomarker and the La Sal Mountainsmarker in Utahmarker intermix into the central and southern parts of the Colorado Plateau.It is composed of seven sections:



As the name implies, the High Plateaus Section is, on average, the highest section. North-south trending normal faults that include the Hurricane, Sevier, Grand Wash, and Paunsaugunt separate the section's component plateaus. This fault pattern is caused by the tensional forces pulling apart the adjacent Basin and Range province to the west, making this section transitional.

Occupying the southeast corner of the Colorado Plateau is the Datil Section. Thick sequences of mid-Tertiary to late-Cenozoic-aged lava covers this section.







Development of the province has in large part been influenced by structural features in its oldest rocks. Part of the Wasatch Line and its various faults form the western edge of the province. Faults that run parallel to the Wasatch Fault that lies along the Wasatch Range form the boundaries between the plateaus in the High Plateaus Section. The Uinta Basin, Uncompahgre Uplift, and the Paradox Basin were also created by movement along structural weaknesses in the region's oldest rock.

In Utah, the province includes several higher fault-separated plateaus:

Some sources also include the Tushar Mountain Plateau as part of the Colorado Plateau, but others do not. The mostly flat-lying sedimentary rock units that make up these plateaus are found in component plateaus that are between 1500 m (5000 ft) to over 3350 m (11,000 ft) above sea level. A supersequence of these rocks is exposed in the various cliffs and canyons (including the Grand Canyonmarker) that make up the Grand Staircase. Increasingly younger east-west trending escarpments of the Grand Staircase extend north of the Grand Canyon and are named for their color:

  • Chocolate Cliffs,
  • Vermillion Cliffs,
  • White Cliffs,
  • Gray Cliffs, and the
  • Pink Cliffs.


Within these rocks are abundant mineral resources that include uranium, coal, petroleum, and natural gas. Study of the area's unusually clear geologic history (which is laid bare due to the arid and semiarid conditions) has greatly advanced that science.

A rain shadow from the Sierra Nevada far to the west and the many ranges of the Basin and Range means that the Colorado Plateau receives 15 to 40 cm (6 to 16 in.) of annual precipitation. Higher areas receive more precipitation and are covered in forests of pine, fir, and spruce.

Though it can be said that the Plateau roughly centers on the Four Corners, Black Mesa in northern Arizona is much closer to the east-west, north-south midpoint of the Plateau Province. Lying southeast of Glen Canyon and southwest of Monument Valley at the north end of the Hopi Reservation, this remote coal-laden highland has about half of the Colorado Plateau's acreage north of it, half south of it, half west of it, and half east of it.

History

The Anasazi lived in the region from around 2000 to 700 years ago.

A party from Santa Fe led by Fathers Dominguez and Escalante, unsuccessfully seeking an overland route to California, made a five-month out-and-back trip through much of the Plateau in 1776-1777.

U.S. Army Major and geologist John Wesley Powell explored the area in 1869 and 1872 despite having lost one arm in the American Civil War. Using fragile boats and small groups of men the Powell Geographic Expedition charted this largely unknown region of the United States for the federal government.

Construction of the Hoover Dammarker in the 1930s and the Glen Canyon Dammarker in the 1960s changed the character of the Colorado River. Dramatically reduced sediment load changed its color from reddish brown (Colorado is Spanish for "colored" referring to its red color) to mostly clear. The apparent green color is from algae on the riverbed's rocks, not from any significant amount of suspended material. The lack of sediment has also starved sand bars and beaches but an experimental 12 day long controlled flood from Glen Canyon Dam in 1996 showed substantial restoration. Similar floods are planned for every 5 to 10 years.

Geology

The Colorado River near Grand Junction, Colorado.


One of the most geologically intriguing features of the Colorado Plateau is its remarkable stability. Relatively little rock deformation such as fault and fold has affected this high, thick crustal block within the last 600 million years or so. In contrast, provinces that have suffered severe deformation surround the plateau. Mountain building thrust up the Rocky Mountains to the north and east and tremendous, earth-stretching tension created the Basin and Range province to the west and south. Sub ranges of the Southern Rocky Mountains are scattered throughout the Colorado Plateau.

The Precambrian and Paleozoic history of the Colorado Plateau is best revealed near its southern end where the Grand Canyonmarker has exposed rocks with ages that span almost 2 billion years. The oldest rocks at river level are igneous and metamorphic and have been lumped together as "Vishnu Basement Rocks;" the oldest ages recorded by these rocks fall in the range 1950 to 1680 million years. An erosion surface on the "Vishnu Basement Rocks" is covered by sedimentary rocks and basalt flows, and these rocks formed in the interval from about 1250 to 750 million years ago: in turn, they were uplifted and split into a range of fault-block mountains. Erosion greatly reduced this mountain range prior to the encroachment of a seaway along the passive western edge of the continent in the early Paleozoic. At the canyon rim is the Kaibab Formation, limestone deposited in the late Paleozoic (Permian) about 270 million years ago.

The red cliffs of the Colorado Plateau tower above the northern Mojave Desert.
Erosion-resistant sandstones of Mesozoic age result in bands of continuous cliffs, central Colorado Plateau
MODIS image of Grand Canyon, Lake Powell and the Colorado Plateau
A 12,000 to 15,000 ft. (3700 to 4600 m) high extension of the Ancestral Rocky Mountains called the Uncompahgre Mountains were uplifted and the adjacent Paradox Basin subsided. Almost 4 mi. (6.4 km) of sediment from the mountains and evaporites from the sea were deposited (see geology of the Canyonlands area for detail).Most of the formations were deposited in warm shallow seas and near-shore environments (such as beaches and swamps) as the seashore repeatedly advanced and retreated over the edge of a proto-North America (for detail, see geology of the Grand Canyon area). The province was probably on a continental margin throughout the late Precambrian and most of the Paleozoic era. Igneous rocks injected millions of years later form a marbled network through parts of the Colorado Plateau's darker metamorphic basement. By 600 million years ago North America had been leveled off to a remarkably smooth surface.

Throughout the Paleozoic Era, tropical seas periodically inundated the Colorado Plateau region. Thick layers of limestone, sandstone, siltstone, and shale were laid down in the shallow marine waters. During times when the seas retreated, stream deposits and dune sands were deposited or older layers were removed by erosion. Over 300 million years passed as layer upon layer of sediment accumulated.

It was not until the upheavals that coincided with the formation of the supercontinent Pangea began about 250 million years ago that deposits of marine sediment waned and terrestrial deposits dominate. In late Paleozoic and much of the Mesozoic era the region was affected by a series of orogenies (mountain-building events) that deformed western North America and caused a great deal of uplift. Eruptions from volcanic mountain ranges to the west buried vast regions beneath ashy debris. Short-lived rivers, lakes, and inland seas left sedimentary records of their passage. Streams, ponds and lakes created formations such as the Chinle, Moenave, and Kayenta in the Mesozoic era. Later a vast desert formed the Navajo and Temple Cap formations and dry near-shore environment formed the Carmel (see geology of the Zion and Kolob canyons area for details).

The area was again covered by a warm shallow sea when the Cretaceous Seaway opened in late Mesozoic time. The Dakota Sandstone and the Tropic Shale were deposited in the warm shallow waters of this advancing and retreating seaway. Several other formations were also created but were mostly eroded following two major periods of uplift.

The Laramide orogeny closed the seaway and uplifted a large belt of crust from Montanamarker to Mexicomarker, with the Colorado Plateau region being the largest block. Thrust faults in Coloradomarker are thought to have formed from a slight clockwise movement of the region, which acted as a rigid crustal block. The Colorado Plateau Province was uplifted largely as a single block, possibly due to its relative thickness. This relative thickness may be why compressional forces from the orogeny were mostly transmitted through the province instead of compacting it. Pre-existing weaknesses in Precambrian rocks were reactivated by the compression. It was along these ancient faults and other deeply-buried structures that much of the province's relatively small and gently-inclined flexures (such as anticlines, synclines, and monoclines) formed. Some of the prominent isolated mountain ranges of the Plateau, such as Ute Mountainmarker and the Carrizo Mountainsmarker, both near the Four Corners, are cored by igneous rocks that were intruded about 70 million years ago, during the Laramide orogeny.

Minor uplift events continued through the start of the Cenozoic era and were accompanied by some basaltic lava eruptions and mild deformation. The colorful Claron Formation that forms the delicate hoodoo of Bryce Amphitheater and Cedar Breaks was then laid down as sediments in cool streams and lakes (see geology of the Bryce Canyon area for details). The flat-lying Chuska Sandstone was deposited about 34 million years ago; the sandstone is predominantly of eolian origin and locally more than 500 meters thick. The Chuska Sandstone caps the Chuska mountainsmarker, and it lies unconformably on Mesozoic rocks deformed during the Laramide orogeny.

Younger igneous rocks form spectacular topographic features. The Henry Mountains, La Sal Rangemarker, and Abajo Mountains, ranges that dominate many views in southeastern Utah, are formed about igneous rocks that were intruded in the interval from 20 to 31 million years: some igneous intrusions in these mountains form laccoliths, a form of intrusion recognized by Grove Karl Gilbert during his studies of the Henry Mountains. Ship Rock (also called Shiprockmarker), in northwestern New Mexico, and Church Rock and Agathlamarker, near Monument Valley, are erosional remnants of potassium-rich igneous rocks and associated breccias of the Navajo Volcanic Field, produced about 25 million years ago. The Hopi Buttes in northeastern Arizona are held up by resistant sheets of sodic volcanic rocks, extruded about 7 million years ago. More recent igneous rocks are concentrated nearer the margins of the Colorado Plateau. The San Francisco Peaksmarker near Flagstaffmarker, south of the Grand Canyonmarker, are volcanic landforms produced by igneous activity that began in that area about 6 million years ago and continued until 1064 C.E., when basalt erupted in Sunset Crater National Monumentmarker. Mount Taylormarker, near Grants, New Mexicomarker, is a volcanic structure with a history similar to that of the San Francisco Peaks: a basalt flow closer to Grants was extruded only about 3000 years ago (see El Malpais National Monumentmarker). These young igneous rocks may record processes in the Earth's mantle that are eating away at deep margins of the relatively stable block of the Plateau.

Tectonic activity resumed in Mid Cenozoic time and started to unevenly uplift and slightly tilt the Colorado Plateau region and the region to the west some 20 million years ago (as much as 3 kilometers of uplift occurred). Streams had their gradient increased and they responded by downcutting faster. Headward erosion and mass wasting helped to erode cliffs back into their fault-bounded plateaus, widening the basins in-between. Some plateaus have been so severely reduced in size this way that they become mesas or even buttes. Monoclines form as a result of uplift bending the rock units. Eroded monoclines leave steeply tilted resistant rock called a hogback and the less steep version is a cuesta.



Great tension developed in the crust, probably related to changing plate motions far to the west. As the crust stretched, the Basin and Range province broke up into a multitude of down-dropped valleys and elongate mountains. Major faults, such as the Hurricane Fault, developed that separate the two regions. The dry climate was in large part a rainshadow effect resulting from the rise of the Sierra Nevada further west. Yet for some reason not fully understood, the neighboring Colorado Plateau was able to preserve its structural integrity and remained a single tectonic block. Eventually, the great block of Colorado Plateau crust rose a kilometer higher than the Basin and Range. As the land rose, the streams responded by cutting ever deeper stream channels. The most well-known of these streams, the Colorado Rivermarker, began to carve the Grand Canyonmarker less than 6 million years ago in response to sagging caused by the opening of the Gulf of Californiamarker to the southwest.

The Pleistocene epoch brought periodic ice ages and a cooler, wetter climate. This increased erosion at higher elevations with the introduction of alpine glaciers while mid-elevations were attacked by frost wedging and lower areas by more vigorous stream scouring. Pluvial lakes also formed during this time. Glaciers and pluvial lakes disappeared and the climate warmed and became drier with the start of Holocene epoch.

Energy generation

Electrical power generation is one of the major industries that takes place in the Colorado Plateau region. Most electrical generation comes from coal fired power plants.

Natural resources

Petroleum

The rocks of the Colorado Plateau are a source of oil and a major source of natural gas. Major petroleum deposits are present in the San Juan Basin of New Mexicomarker and Coloradomarker, the Uinta Basin of Utahmarker, the Piceance Basin of Coloradomarker, and the Paradox Basinmarker of Utahmarker, Coloradomarker, and Arizonamarker.

Uranium

The Colorado Plateau holds major uranium deposits, and there was a Uranium boom in the 1950s. (See Uranium mining in Utah and Uranium mining in the United States). The Atlas Uranium Millmarker near Moab has left a problematic tailings pile for cleanup.

Coal

Major coal deposits are being mined in the Colorado Plateau in Utahmarker, Arizonamarker, Coloradomarker, and New Mexicomarker, though large coal mining projects, such as on the Kaiparowitz Plateau, have been proposed and defeated politically. The ITT Power Project, eventually located in Lynndyl, Utahmarker, near Delta, was originally suggested for Salt Wash near Capitol Reef National Park. After a firestorm of opposition, it was moved to a less beloved site. In Utah the largest deposits are in aptly named Carbon County. In Arizona the biggest operation is on Black Mesa, supplying coal to Navajo Power Plant.

Gilsonite, uintatite

Perhaps the only one of its kind, a gilsonite plant near Bonanza, southeast of Vernal, Utahmarker, mines this unique, lustrous, brittle form of asphalt, for use in "varnishes, paints, . . . ink, waterproofing compounds, electrical insulation, . . . roofing materials." (Utah: A Guide to the State, 1982, p. 590)

Oil shale

Huge deposits of oil shale, primarily in the northeastern Colorado Plateau, lie waiting for improved technology to tap their riches.

Scenic beauty

The scenic appeal of this unique landscape had become, well before the end of the twentieth century, its greatest financial natural resource. The amount of commercial benefit to the four states of the Colorado Plateau from tourism exceeded that of any other natural resource.

Protected lands

This relatively high semi-arid province produces many distinctive erosional features such as arches, arroyo, canyons, cliffs, fins, natural bridge, pinnacles, hoodoo, and monoliths that, in various places and extents, have been protected. Also protected are areas of historic or cultural significance, such as the pueblos of the Anasazi culture. There are nine U.S. National Parks, a National Historical Park, sixteen U.S. National Monuments and dozens of wilderness areas in the province along with millions of acres in U.S. National Forests, many state parks, and other protected lands. In fact, this region has the highest concentration of parklands in North America. Lake Powellmarker, in foreground, is not a natural lake but a reservoir impounded by Glen Canyon Dammarker.

National parks (from south to north to south clockwise):

National Monuments (alphabetical):

Wilderness areas:


Other notable protected areas include: Glen Canyon National Recreation Areamarker, Dead Horse Point State Parkmarker, Goosenecks State Parkmarker, the San Rafael Swellmarker, the Grand Gulch Primitive Area, Kodachrome Basin State Parkmarker, Goblin Valley State Parkmarker and Barringer Cratermarker.

Sedona, Arizona and Oak Creek Canyon lie on the south-central border of the Plateau. Many but not all of the Sedona area's cliff formations are protected as wilderness. The area has the visual appeal of a national park, but with a small, rapidly growing town in the center.

Colorado Plateau scenes

Image:Grand Junction Trip 92007 052.JPG|Rabbit Valley, Colorado near Interstate 70.Image:GrandJunctionTrip92007013.jpg|View of the Western Slope of the Rocky Mountains near Grand Junction, Coloradomarker.File:Stgeorge 085 edited.jpg|The Virgin River Gorge, Arizona. This is where the Colorado Plateau and the Mojave Desert meet.File:Grand Junction Trip 92007 074.JPG|Mesa in Grand County, Utahmarker.Image:Window Arch, Arches.jpg|North Window at Arches National Parkmarker, Utah.File:Grand Jct2 005.JPG|Junipers top a butte in Coloradomarker.Image:Spring in Northwest New Mexico.jpg|Spring in northwestern New Mexico.Image:San Rafael Swell01.jpg|San Rafael Swellmarker in central Utah.

See also

Deserts,Rocky Mountains,Mojave Desert,Great Basin,Sonoran Desertmarker

References

  1. Kiver, Eugene P. and David V. Harris, 1999, Geology of U.S. Parklands, Wiley, 5th ed., page 395, ISBN 0-471-33218-6
  2. Geology of U.S. Parklands, page 367, figure 8-1
  3. Geology of U.S. Parklands, page 366
  4. Geology of U.S. Parklands, page 376
  5. Geology of U.S. Parklands, page 369
  6. Geology of U.S. Parklands, page 369
  7. Geology of U.S. Parklands, page 374, "Trouble in Paradise"
  8. Gregory Crampton, Standing Up Country, Alfred Knopf, NY, 1964, pp. 43-46
  9. Geology of U.S. Parklands, page 375
  10. For the whole paragraph except where noted: Geology of U.S. Parklands, page 383, "Precambrian and Paleozoic"
  11. Geology of U.S. Parklands, page 383
  12. Geology of U.S. Parklands, page 376
  13. Geology of U.S. Parklands, page 376
  14. Geology of U.S. Parklands, page 365
  • Kiver, Eugene P. and David V. Harris, 1999, Geology of U.S. Parklands, Wiley, 5th ed., ISBN 0-471-33218-6


Further reading

Prickly Pear cactus are common throughout the Colorado Plateau region.
  • Donald L. Baars, Red Rock Country: The Geologic History of the Colorado Plateau, Doubleday (1972), hardcover, ISBN 0-385-01341-8
  • Donald L. Baars, Traveler's Guide to the Geology of the Colorado Plateau, University of Utah Press (2002), trade paperback, 250 pages, ISBN 0-87480-715-8
  • W. Scott Baldridge, Geology of the American Southwest: A Journey Through Two Billion Years of Plate-Tectonic History, Cambridge University Press (2004), 280 pages, ISBN 0-521-01666-5
  • Crampton, C. Gregory, Standing Up Country: The Canyon Lands of Utah and Arizona, Rio Nuevo Publishers (September 2000), ISBN 1887896155
  • Geology of National Parks: Fifth Edition, Ann G. Harris, Esther Tuttle, Sherwood D., Tuttle (Iowa, Kendall/Hunt Publishing; 1997), pages 2–3, 19-20, 25 ISBN 0-7872-5353-7
  • Physical Geology: Eight Edition, Plummer, McGeary, Carlson, (McGraw-Hill: Boston; 1999), page 320 ISBN 0-697-37404-1
  • Earth System History, Steven M. Stanley, (W.H. Freeman and Company; 1999), pages 511-513, 537 ISBN 0-7167-2882-6
  • USGS - Geologic Provinces of the United States: Colorado Plateau Province (some adapted public domain text)
  • Annabelle Foos, Geology of the Colorado Plateau, National Park Service PDF Accessed 12/21/2005.
  • Ward Roylance, Utah: A Guide to the State, Utah: A Guide to the State Foundation; Salt Lake City; 1982; 779 pp
  • Look, Al, 1947, A Thousand Million Years on the Colorado Plateau, Golden Bell Publications, Fifth printing 1971, 300 pages.
  • The Bright Edge, Subtitle: Guide to the National Parks of the Colorado Plateau.


External links


Embed code:






Got something to say? Make a comment.
Your name
Your email address
Message