Colorado Plateau

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A map of the Colorado Plateau. Colorado Plateaus map.png
A map of the Colorado Plateau.
The Four Corners region and the Colorado Plateau. Click image to see state lines. Four corners.jpg
The Four Corners region and the Colorado Plateau. Click image to see state lines.

The Colorado Plateau, also known as the Colorado Plateau Province, [1] is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area of 336,700 km2 (130,000 mi2) within western Colorado, northwestern New Mexico, southern and eastern Utah, northern Arizona, and a tiny fraction in the extreme southeast of Nevada. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries. [2] [3] :395

Contents

The Colorado Plateau is largely made up of high desert, with scattered areas of forests. In the southwest corner of the Colorado Plateau lies the Grand Canyon of the Colorado River and Mount Taylor. Much of the 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, 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 U.S. National Park Service (NPS) units in the country outside the Washington, DC metropolitan area. Among its nine national parks are Grand Canyon, Zion, Bryce Canyon, Capitol Reef, Canyonlands, Arches, Mesa Verde, and Petrified Forest. Among its 18 national monuments are Bears Ears, Rainbow Bridge, Dinosaur, Hovenweep, Wupatki, Sunset Crater Volcano, Grand Staircase-Escalante, Natural Bridges, Canyons of the Ancients, Chaco Culture National Historical Park and the Colorado National Monument.

Geography

The Book Cliffs of Utah. Bookcliffs.helperUT.jpg
The Book Cliffs of Utah.
The Green River runs north to south from Wyoming, briefly through Colorado, and converges with the Colorado River in southeastern Utah. Confluence of Green and Colorado Rivers.jpg
The 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 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 Province. 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. 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. [3] :376 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 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 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 six to sixteen inches (15 to 40 cm) of annual precipitation. [3] :369 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.

Human history

The Ancestral Puebloan People lived in the region from roughly 2000 to 700 years ago. [3] :374 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. [4] Despite having lost one arm in the American Civil War, U.S. Army Major and geologist John Wesley Powell explored the area in 1869 and 1872. Using wooden oak 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 Dam in the 1930s and the Glen Canyon Dam in the 1960s changed the character of the Colorado River. Dramatically reduced sediment load changed its color from reddish brown (Colorado is Spanish for "red-colored") 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. [3] :375

Geology

MODIS satellite image of Grand Canyon, Lake Powell (black, left of center) and the Colorado Plateau. White areas are snow-capped. MODIS1000013.jpg
MODIS satellite image of Grand Canyon, 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. SEUtahStrat.JPG
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, UT. AntelopeIslandEchoGhosttowns 221.jpg
Castle Gate rock formation in Carbon County, UT.
Navajo sandstone cliffs in Zion National Park. Zion 04.jpg
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 created the Basin and Range Province to the west and south. Sub ranges of the Southern Rocky Mountains are scattered throughout the Colorado Plateau. [5]

The Precambrian and Paleozoic history of the Colorado Plateau is best revealed near its southern end where the Grand Canyon 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. [3] :383 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.

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 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 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 Cenozoic era and were accompanied by some basaltic lava eruptions and mild deformation. The colorful 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 Henry Mountains, La Sal Range, 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 Shiprock), in northwestern New Mexico, and Church Rock and Agathla, 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 Peaks near Flagstaff, south of the Grand Canyon, are volcanic landforms produced by igneous activity that began in that area about 6 million years ago and continued until 1064 CE, when basalt erupted in 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 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. [5]

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 USARRAY project. It was found that the asthenosphere had invaded the overlying lithosphere, as a result of an area of mantle upwelling stemming from either the disintegration of the descending Farallon Plate, or the survival of the subducted spreading center connected to the East Pacific Rise and Gorda Ridge beneath western North America, or possibly both. The asthenosphere erodes the lower levels of the Plateau. At the same time, as it cools, it expands and lifts the upper layers of the Plateau. [6] 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 River, began to carve the Grand Canyon less than 6 million years ago. [5]

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.

Ecology

Sunset in Ojito Wilderness, near Albuquerque, NM Sunset in Ojito Wilderness, NM.jpg
Sunset in Ojito Wilderness, near Albuquerque, NM

The Colorado Plateau is covered with dry grasslands and shrublands, open pinyon-juniper woodland, and mountain woodlands and forests. [7]

Energy resources

Castle Gate Power Plant near Helper, UT. Caron Power Plant - Utah (corrected).png
Castle Gate Power Plant near Helper, UT.

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. 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 Mexico and Colorado, the Uinta Basin of Utah, the Piceance Basin of Colorado, and the Paradox Basin of Utah, Colorado, and Arizona. The Colorado Plateau holds major uranium deposits, and there was a uranium boom in the 1950s. The Atlas Uranium Mill near Moab has left a problematic tailings pile for cleanup, which is ongoing.[ citation needed ] Major coal deposits are being mined in the Colorado Plateau in Utah, Arizona, Colorado, and New Mexico, though large coal mining projects, such as on the Kaiparowits Plateau, have been proposed and defeated politically. The ITT Power Project, eventually located in Lynndyl, Utah, 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. Perhaps the only one of its kind, a 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." [8]

Protected lands

This relatively high, semi-arid to arid province produces many distinctive erosional features such as arches, arroyos, canyons, cliffs, fins, natural bridges, pinnacles, hoodoos, 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 Ancestral Puebloan 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. [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.

See also

Related Research Articles

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Intermontane Plateaus

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Natural Bridges National Monument National monument in San Juan County, Utah, USA

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Geology of the Yosemite area

The exposed geology of the Yosemite area includes primarily granitic rocks with some older metamorphic rock. The first rocks were laid down in Precambrian times, when the area around Yosemite National Park was on the edge of a very young North American continent. The sediment that formed the area first settled in the waters of a shallow sea, and compressive forces from a subduction zone in the mid-Paleozoic fused the seabed rocks and sediments, appending them to the continent. Heat generated from the subduction created island arcs of volcanoes that were also thrust into the area of the park. In time, the igneous and sedimentary rocks of the area were later heavily metamorphosed.

Geology of the United States national geology

The richly textured landscape of the United States is a product of the dueling forces of plate tectonics, weathering and erosion. Over the 4.5 billion-year history of our Earth, tectonic upheavals and colliding plates have raised great mountain ranges while the forces of erosion and weathering worked to tear them down. Even after many millions of years, records of Earth's great upheavals remain imprinted as textural variations and surface patterns that define distinctive landscapes or provinces.

Geology of the Grand Canyon area Aspect of geology

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.

Geology of the Zion and Kolob canyons area Geology of Zion National Park in Utah

The geology of the Zion and Kolob canyons area includes nine known exposed formations, all visible in Zion National Park in the U.S. state of Utah. Together, these formations represent about 150 million years of mostly Mesozoic-aged sedimentation in that part of North America. Part of a super-sequence of rock units called the Grand Staircase, the formations exposed in the Zion and Kolob area were deposited in several different environments that range from the warm shallow seas of the Kaibab and Moenkopi formations, streams and lakes of the Chinle, Moenave, and Kayenta formations to the large deserts of the Navajo and Temple Cap formations and dry near shore environments of the Carmel Formation.

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.

Grand Staircase

The Grand Staircase is an immense sequence of sedimentary rock layers that stretch south from Bryce Canyon National Park and Grand Staircase-Escalante National Monument, through Zion National Park, and into the Grand Canyon National Park.

Geology of the Grand Teton area

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.

Geology of the Capitol Reef area

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.

Geology of the Death Valley area Geology of the area in California and Nevada

The exposed geology of the Death Valley area presents a diverse and complex set of at least 23 formations of sedimentary units, two major gaps in the geologic record called unconformities, and at least one distinct set of related formations geologists call a group. The oldest rocks in the area that now includes Death Valley National Park are extensively metamorphosed by intense heat and pressure and are at least 1700 million years old. These rocks were intruded by a mass of granite 1400 Ma and later uplifted and exposed to nearly 500 million years of erosion.

Canyons of the Escalante

The Canyons of the Escalante is a collective name for the erosional landforms created by the Escalante River and its tributaries—the Escalante River Basin. Located in southern Utah in the western United States, these sandstone features include high vertical canyon walls, numerous slot canyons, waterpockets, domes, hoodoos, natural arches and bridges. This area—extending over 1,500 square miles (3,885 km2) and rising in elevation from 3,600 ft (1,097 m) to over 11,000 ft (3,353 m)—is one of the three main sections of the Grand Staircase-Escalante National Monument, and also a part of the Glen Canyon National Recreation Area, with Capitol Reef National Park being adjacent to the east.

Geology of North America Overview of the geology of North America

The geology of North America is a subject of regional geology and covers the North American continent, the third-largest in the world. Geologic units and processes are investigated on a large scale to reach a synthesized picture of the geological development of the continent.

Unkar Group

The Unkar Group is a sequence of strata of Proterozoic age that are subdivided into five geologic formations and exposed within the Grand Canyon, Arizona, Southwestern United States. The 5-unit Unkar Group is the basal member of the 8-member Grand Canyon Supergroup. The Unkar is about 1,600 to 2,200 m thick and composed, in ascending order, of the Bass Formation, Hakatai Shale, Shinumo Quartzite, Dox Formation, and Cardenas Basalt. Units 4 & 5 are found mostly in the eastern region of Grand Canyon. Units 1 through 3 are found in central Grand Canyon. The Unkar Group accumulated approximately between 1250 and 1104 Ma. In ascending order, the Unkar Group is overlain by the Nankoweap Formation, about 113 to 150 m thick; the Chuar Group, about 1,900 m (6,200 ft) thick; and the Sixtymile Formation, about 60 m (200 ft) thick. These are all of the units of the Grand Canyon Supergroup. The Unkar Group makes up approximately half of the thickness of the 8-unit Supergroup.

Toroweap Fault

The Toroweap Fault of northwest Arizona and southwest Utah is part of a fault system of the west Grand Canyon region, Arizona, USA; also the west perimeter regions of the Coconino and Colorado Plateaus. The Hurricane Fault originates at the Toroweap Fault, in the region of the Colorado River, and strikes as the westerly depression of the Toroweap Fault. The Toroweap strikes northerly from the Colorado at the east of Toroweap Valley, and enters south Utah; from the Colorado River, the Hurricane Fault strikes north-northwest along the west flank of the small, regional Uinkaret Mountains, the west border of Toroweap Valley. The Hurricane Fault, and the Hurricane Cliffs strike into southwest Utah as part of the west, and southwest perimeter of the Colorado Plateau. The Hurricane Cliffs are made of Kaibab Limestone, an erosion resistant, cliff-forming rock unit.

Supai Group

The Pennsylvanian to Lower Permian,, Supai Group, is a slope-forming section of red bed deposits found at the southwest-to-south Colorado Plateau. Cliff-forming interbeds (sandstone) are noticeable throughout the group, as well as the largest cliff-former the topmest member Esplanade Sandstone. The Supai Group is especially exposed throughout the Grand Canyon in northwest Arizona, as well as local regions of southwest Utah. It outcrops southeastwards in Arizona at Chino Point, Sycamore Canyon, and famously at Sedona as parts of Oak Creek Canyon. In the Sedona region, it is overlain by the Hermit Formation, and the colorful Schnebly Hill Formation.

The geology of Arizona began to form in the Precambrian. Igneous and metamorphic crystalline basement rock may have been much older, but was overwritten during the Yavapai and Mazatzal orogenies in the Proterozoic. The Grenville orogeny to the east caused Arizona to fill with sediments, shedding into a shallow sea. Limestone formed in the sea was metamorphosed by mafic intrusions. The Great Unconformity is a famous gap in the stratigraphic record, as Arizona experienced 900 million years of terrestrial conditions, except in isolated basins. The region oscillated between terrestrial and shallow ocean conditions during the Paleozoic as multi-cellular life became common and three major orogenies to the east shed sediments before North America became part of the supercontinent Pangaea. The breakup of Pangaea was accompanied by the subduction of the Farallon Plate, which drove volcanism during the Nevadan orogeny and the Sevier orogeny in the Mesozoic, which covered much of Arizona in volcanic debris and sediments. The Mid-Tertiary ignimbrite flare-up created smaller mountain ranges with extensive ash and lava in the Cenozoic, followed by the sinking of the Farallon slab in the mantle throughout the past 14 million years, which has created the Basin and Range Province. Arizona has extensive mineralization in veins, due to hydrothermal fluids and is notable for copper-gold porphyry, lead, zinc, rare minerals formed from copper enrichment and evaporites among other resources.

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 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. Utah is a state in the western United States.

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. 1 2 3 4 5 6 7 8 9 10 11 12 13 Kiver, Eugene P.; Harris, David V. (1999). Geology of U.S. Parklands (5th ed.). John Wiley & Sons. ISBN   0-471-33218-6.
  4. Crampton, Gregory (1964). Standing Up Country. New York: Alfred Knopf. pp. 43–46.
  5. 1 2 3 PD-icon.svg This article incorporates  public domain material from the United States Geological Survey document: "Colorado Plateau Province". Geologic Provinces of the United States. Archived from the original on 2017-07-09. Retrieved 2017-07-04.
  6. "Why is the Colorado Plateau Rising?". Geology.com. Archived from the original on 2011-05-05. Retrieved 9 May 2011.
  7. "Colorado Plateau shrublands". Terrestrial Ecoregions. World Wildlife Fund.
  8. Utah: A Guide to the State. 1982. p. 590.

Further reading

Coordinates: 37°N110°W / 37°N 110°W / 37; -110