Colorado Plateau

Coordinates: 37°N 110°W / 37°N 110°W / 37; -110
Source: Wikipedia, the free encyclopedia.
A map of the Colorado Plateau.
The Four Corners region and the Colorado Plateau.

The Colorado Plateau, also known as the Colorado Plateau Province,

San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries.[2][3]
: 395 

The Colorado Plateau is largely made up of high desert, with scattered areas of forests. In the south-west corner of the Colorado Plateau lies the

natural bridges, and slot canyons
are only some of the additional features typical of the Plateau.

The Colorado Plateau has the greatest concentration of U.S.

Sunset Crater Volcano, Grand Staircase–Escalante, El Malpais, Natural Bridges, Canyons of the Ancients, Chaco Culture National Historical Park and the Colorado National Monument
.

Geography

The Book Cliffs of Utah
Green River runs north to south from Wyoming, briefly through Colorado, and converges with the Colorado River
in southeastern Utah.

This province is bounded by the

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 Province (at the Hurricane Fault). Isolated ranges of the Southern Rocky Mountains, such as the San Juan Mountains in Colorado and the La Sal Mountains
in Utah, intermix into the central and southern parts of the Colorado Plateau. It is composed of six sections:[3]: 367 

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.[3]: 366  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. The 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 province's western edge. 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.[3]: 376  The Uinta Basin, Uncompahgre Uplift, and the Paradox Basin
were also formed 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 4,900 to 11,000 feet (1,500 to 3,350 m) above sea level. A supersequence of these rocks is exposed in the various cliffs and canyons (including the Grand Canyon) 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:

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

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.

The American Association of Petroleum Geologists divides the Colorado Plateau into four geologic provinces. These are:[4]

  • Plateau Sedimentary Province in northern Arizona and southern Utah
  • Black Mesa Basin
    in northeastern Arizona
  • San Juan Basin in northwestern New Mexico
  • Paradox Basin in southwestern Colorado and southeastern Utah

Human history

The

Powell Geographic Expedition
charted this largely unknown region of the United States for the federal government.

Construction of the

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.[3]: 375 [needs update
]

Geology

MODIS satellite image of Grand Canyon (lower left), Lake Powell
(black, left of center) and the Colorado Plateau. White areas are snow-capped.
The Permian through Jurassic stratigraphy of the Colorado Plateau area of southeastern Utah that makes up much of the famous prominent rock formations in protected areas such as Capitol Reef National Park and Canyonlands National Park. From top to bottom: rounded tan domes of the Navajo Sandstone; layered red Kayenta Formation; cliff-forming, vertically jointed, red Wingate Sandstone; slope-forming, purplish Chinle Formation; layered, lighter-red Moenkopi Formation; and white, layered Cutler Formation sandstone from the Glen Canyon National Recreation Area in Utah.
Castle Gate rock formation in Carbon County, Utah.
Navajo sandstone cliffs in Zion National Park.

One of the most geologically intriguing features of the Colorado Plateau is its remarkable stability. Relatively little rock deformation such as faulting and folding has affected this high, thick crustal block within the last 600 million years or so, although there are some newer features such as the Waterpocket Fold of Capitol Reef (estimated 50–70 million years old). 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 produced the Basin and Range Province to the west and south. Sub ranges of the Southern Rocky Mountains are scattered throughout the Colorado Plateau.[6]

The

fault-block mountains.[3]
: 383  Erosion greatly reduced this mountain range before 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.

A 12,000-to-15,000-foot high (3,700 to 4,600 m) 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).[3]
: 383  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 produced 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 produced but were mostly eroded
following two major periods of uplift.

The Laramide orogeny closed the seaway and uplifted a large belt of crust from Montana to Mexico, with the Colorado Plateau region being the largest block. Thrust faults in Colorado 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 deforming it.[3]: 376  Pre-existing weaknesses in Precambrian rocks were exploited and 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.[3]: 376  Some of the prominent isolated mountain ranges of the Plateau, such as Ute Mountain and the Carrizo Mountains, both near the Four Corners, are cored by igneous rocks that were emplaced about 70 million years ago.

Minor uplift events continued through the start of the

Claron Formation that forms the delicate hoodoos 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 Mountains, and it lies unconformably on Mesozoic rocks deformed during the Laramide orogeny
.

Younger igneous rocks form spectacular topographic features. The

Sunset Crater National Monument. Mount Taylor, near Grants, New Mexico, 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 Monument). 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

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.[6]

A second mystery was that while the lower layers of the Plateau appeared to be sinking, overall the Plateau was rising. The reason for this was discovered upon analyzing data from the

Colorado River, began to carve the Grand Canyon less than 6 million years ago.[6]

The

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.

Ecology

Main article: Colorado Plateau shrublands
Sunset in Ojito Wilderness, near Albuquerque, New Mexico

The Colorado Plateau is covered with dry grasslands and shrublands, open

pinyon-juniper woodland, and mountain woodlands and forests.[9]

Energy resources

See also: Uranium mining in Utah
Castle Gate Power Plant near Helper, Utah
.

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

gilsonite plant near Bonanza, southeast of Vernal, Utah, mines this unique, lustrous, brittle form of asphalt, for use in "varnishes, paints,...ink, waterproofing compounds, electrical insulation,...roofing materials."[12]

Protected lands

This relatively high, semi-arid to arid province produces many distinctive erosional features such as arches,

U.S. National Forests, many state parks, and other protected lands. In fact, this region has the highest concentration of parklands in North America.[3]: 365  Lake Powell, in foreground, is not a natural lake but a reservoir impounded by Glen Canyon Dam
.

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

National monuments (alphabetical):

Wilderness areas (alphabetical):

Other notable protected areas include:

Barringer Crater, Dead Horse Point State Park, Glen Canyon National Recreation Area, Goblin Valley State Park, Goosenecks State Park, the Grand Gulch Primitive Area, Kodachrome Basin State Park, Monument Valley, and the San Rafael Swell. 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 (Red Rock State Park and Coconino National Forest
). The area has the visual appeal of a national park, but with a small, rapidly growing town in the center.

National Park Gallery

See also

References

  1. ^ "Colorado Plateau | plateau, United States". Encyclopædia Britannica. Retrieved 2017-06-05.
  2. ^ Leighty, Robert D. (2001). "Colorado Plateau Physiographic Province". Contract Report. Defense Advanced Research Projects Agency (DOD) Information Sciences Office. Archived from the original on 2004-09-26. Retrieved 2007-12-25.
  3. ^
    ISBN 0-471-33218-6
    .
  4. ^ Moore, B.J. (1982). Analyses of natural gases, 1917–80. Vol. 8870. US Department of the Interior. pp. 4–5. Retrieved 30 October 2021.
  5. ^ Crampton, Gregory (1964). Standing Up Country. New York: Alfred Knopf. pp. 43–46.
  6. ^ a b c Public Domain This article incorporates public domain material from "Colorado Plateau Province". Geologic Provinces of the United States. United States Geological Survey. Archived from the original on 2017-07-09. Retrieved 2017-07-04.
  7. S2CID 4322477
    .
  8. ^ "Why is the Colorado Plateau Rising?". Geology.com. Archived from the original on 2011-05-05. Retrieved 9 May 2011.
  9. ^ "Colorado Plateau shrublands". Terrestrial Ecoregions. World Wildlife Fund.
  10. ^ "Moab's steady progress through a decade of cleanup". Office of Environmental Management. U.S. Department of Energy. 12 September 2019. Retrieved 20 June 2022.
  11. ^ Kotkin, Joel (3 July 1978). "Coal-fired power plant apparently finds a home". The Washington Post. Retrieved 20 June 2022.
  12. ^ Utah: A Guide to the State. 1982. p. 590.

Further reading

External links

37°N 110°W / 37°N 110°W / 37; -110

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