The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is 277 miles long, up to 18 miles wide and attains a depth of over a mile; the canyon and adjacent rim are contained within Grand Canyon National Park, the Kaibab National Forest, Grand Canyon-Parashant National Monument, the Hualapai Indian Reservation, the Havasupai Indian Reservation and the Navajo Nation. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, visited it on numerous occasions to hunt and enjoy the scenery. Nearly two billion years of Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. While some aspects about the history of incision of the canyon are debated by geologists, several recent studies support the hypothesis that the Colorado River established its course through the area about 5 to 6 million years ago.
Since that time, the Colorado River has driven the down-cutting of the tributaries and retreat of the cliffs deepening and widening the canyon. For thousands of years, the area has been continuously inhabited by Native Americans, who built settlements within the canyon and its many caves; the Pueblo people considered the Grand Canyon a holy site, made pilgrimages to it. The first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain, who arrived in 1540; the Grand Canyon is a river valley in the Colorado Plateau that exposes uplifted Proterozoic and Paleozoic strata, is one of the six distinct physiographic sections of the Colorado Plateau province. It is not the deepest canyon in the world. However, the Grand Canyon is known for its visually overwhelming size and its intricate and colorful landscape. Geologically, it is significant because of the thick sequence of ancient rocks that are well preserved and exposed in the walls of the canyon; these rock layers record much of the early geologic history of the North American continent.
Uplift associated with mountain formation moved these sediments thousands of feet upward and created the Colorado Plateau. The higher elevation has resulted in greater precipitation in the Colorado River drainage area, but not enough to change the Grand Canyon area from being semi-arid; the uplift of the Colorado Plateau is uneven, the Kaibab Plateau that Grand Canyon bisects is over one thousand feet higher at the North Rim than at the South Rim. All runoff from the North Rim flows toward the Grand Canyon, while much of the runoff on the plateau behind the South Rim flows away from the canyon; the result is deeper and longer tributary washes and canyons on the north side and shorter and steeper side canyons on the south side. Temperatures on the North Rim are lower than those on the South Rim because of the greater elevation. Heavy rains are common on both rims during the summer months. Access to the North Rim via the primary route leading to the canyon is limited during the winter season due to road closures.
The Grand Canyon is part of the Colorado River basin which has developed over the past 70 million years, in part based on apatite /He thermochronometry showing that Grand Canyon reached a depth near to the modern depth by 20 Ma. A recent study examining caves near Grand Canyon places their origins beginning about 17 million years ago. Previous estimates had placed the age of the canyon at 5–6 million years; the study, published in the journal Science in 2008, used uranium-lead dating to analyze calcite deposits found on the walls of nine caves throughout the canyon. There is a substantial amount of controversy because this research suggests such a substantial departure from prior supported scientific consensus. In December 2012, a study published in the journal Science claimed new tests had suggested the Grand Canyon could be as old as 70 million years. However, this study has been criticized by those who support the "young canyon" age of around six million years as " attempt to push the interpretation of their new data to their limits without consideration of the whole range of other geologic data sets."The canyon is the result of erosion which exposes one of the most complete geologic columns on the planet.
The major geologic exposures in the Grand Canyon range in age from the 2-billion-year-old Vishnu Schist at the bottom of the Inner Gorge to the 230-million-year-old Kaibab Limestone on the Rim. There is a gap of about a billion years between the 500-million-year-old stratum and the level below it, which dates to about 1.5 billion years ago. This large unconformity indicates a long period. Many of the formations were deposited in warm shallow seas, near-shore environments, swamps as the seashore advanced and retreated over the edge of a proto-North America. Major exceptions include the Permian Coconino Sandstone, which contains abundant geological evidence of aeolian sand dune deposition. Several parts of the Supai Group were deposited in non–marine environments; the great depth of the Grand Canyon and the height of its strata can be attributed to 5–10 thousand feet of uplift of the Colorado Plateau, starting about 65 million years ago. This uplift has steepened the stream gradient of the Colorado River
The Dolores River is a tributary of the Colorado River 241 miles long, in the U. S. states of Utah. The river drains a arid region of the Colorado Plateau west of the San Juan Mountains, its name derives from River of Our Lady of Sorrows. The river was explored and named by Juan Maria Antonio Rivera during a 1765 expedition from Santa Fe; the mean annual flow of the Dolores prior to damming was 1,200 cu ft/s, but due to diversions it has been reduced to about 600 cu ft/s. The Dolores River rises in a meadow called Tin Can Basin, near 12,520-foot Hermosa Peak in the San Miguel Mountains, in Dolores County, Colorado; the headwaters are located about 5 miles south of Lizard Head Pass in the San Juan National Forest. The river flows southwest in a canyon past Rico, receiving the West Dolores River flows into McPhee Reservoir near Dolores in Montezuma County. Formed by McPhee Dam, the reservoir is about 10 miles long and diverts flows of the upper Dolores River for irrigation. Downstream from McPhee Dam, the river re-enters Dolores County and carves the Dolores River Canyon, which stretches north for over 40 miles and averages 1,100 feet deep.
This section of the Dolores River is noted for its exposed sedimentary strata, desert wildlife, during years of heavy snowmelt for its whitewater. Near Egnar the river crosses into San Miguel County and from there into Montrose County. Continuing north, the Dolores cuts across the Paradox Valley which runs in an unusual transverse direction to the river. Below Paradox Valley it is joined by the San Miguel River, its main tributary, from the east. Due to diversions on the main stem, the San Miguel is the same size as the Dolores if not larger, providing most of the flow below the confluence in dry years. Below the confluence with the San Miguel, the Dolores enters Mesa County, flowing north-northwest past Gateway and turning west into Utah; the last segment of the river within Grand County, joins the Colorado near the historic Dewey Bridge, about 30 miles above Moab. Measured at Cisco, not far above the confluence with the Colorado River, the average unimpaired discharge of the Dolores River between 1906 and 1995 was 841,000 acre feet, or about 1,160 cubic feet per second.
The United States Geological Survey has operated a stream gage at Cisco from 1950 to the present. For the 36-year period December 1950 to September 1986, the river flow at Cisco averaged 845 cubic feet per second. By contrast, in the 27 years from October 1986 to October 2013, the river averaged only 599 cubic feet per second due to the McPhee Dam diversions. Measured at Bedrock, Colorado, at the entrance to Paradox Valley the effect of the flow reductions is more obvious, with an average of 504 cubic feet per second before September 1984 as compared to 240 cubic feet per second between October 1984 and May 2014; the ancestral Dolores River is believed to have flowed south to join the San Juan River near the Four Corners in what is now northwestern New Mexico. The uplift of Sleeping Ute Mountain about 70 million years ago diverted the Dolores River to its present northward course, causing it to carve the Dolores River Canyon on its way to the Colorado River, creating unusual geologic features such as the Paradox Valley.
The Dolores Canyon exposes rocks ranging from 300-million-year-old Pennsylvanian limestone to the 140-million-year-old Entrada sandstone deposited during the Jurassic. A cap of Cretaceous Dakota sandstone forms most of the upper rim of the canyon; the lower Dolores River may have once been the original course of the Colorado River, which flowed through the now dry Unaweep Canyon occupied by West Creek, a small tributary of the Dolores. When the Uncompahgre Plateau was formed it diverted the larger Colorado northwards through what is now the Grand Valley, looping around through Westwater Canyon to the confluence with the Dolores in eastern Utah and leaving Unaweep Canyon as a huge dry gap across the plateau. However, some geologists contend that the Colorado never flowed through Unaweep and the lower Dolores River, as the erosive force of the river should have created a water gap here; the Dolores is dammed at McPhee Reservoir near Cortez, Colorado to irrigate about 61,660 acres of arid plateau land.
The dam and diversion canals are operated by the Bureau of Reclamation as the Dolores Project. In some years all the water entering the reservoir is diverted, leaving only a small mandated minimum flow to pass downstream, as a result reducing the 150 mile stretch between the dam and the confluence of the San Miguel River to a large creek; the construction of the dam allowed local farmers to extend the irrigation season through September whereas natural river flows would have been insufficient by July or August. While the dam has reduced and sometimes halted spring peak flows in the lower Dolores, it provides supplemental flows in late summer in the range of 75 cubic feet per second, maintaining downstream fisheries. Before the dam was built, irrigators diverted nearly the entire flow of the river, leaving as little as 10 cubic feet per second to flow downstream. Releases from McPhee Dam are a controversial topic; the Bureau of Reclamation operates McPhee on a "fill spill" policy, where the dam is filled
Sonora Estado Libre y Soberano de Sonora, is one of 31 states that, with Mexico City, comprise the 32 federal entities of United Mexican States. It is divided into 72 municipalities. Sonora is bordered by the states of Chihuahua to the east, Baja California to the northwest and Sinaloa to the south. To the north, it shares the U. S.–Mexico border with the states of Arizona and New Mexico, on the west has a significant share of the coastline of the Gulf of California. Sonora's natural geography is divided into three parts: the Sierra Madre Occidental in the east of the state, it is arid or semiarid deserts and grasslands, with only the highest elevations having sufficient rainfall to support other types of vegetation. Sonora is home to eight indigenous peoples, including the Mayo, the O’odham, the Yaqui, Seri, it has been economically important for its agriculture and mining since the colonial period, for its status as a border state since the Mexican–American War. With the Gadsden Purchase, Sonora lost more than a quarter of its territory.
From the 20th century to the present, industry and agribusiness have dominated the economy, attracting migration from other parts of Mexico. Several theories exist as to the origin of the name "Sonora". One theory states that the name was derived from Nuestra Señora, the name given to the territory when Diego de Guzmán crossed the Yaqui River on the day of Nuestra Señora del Rosario, which falls on 7 October with the pronunciation changing because none of the indigenous languages of the area have the ñ sound. Another theory states that Álvar Núñez Cabeza de Vaca and his companions, who had wrecked off the Florida coast and made their way across the continent, were forced to cross the arid state from north to south, carrying an image of Nuestra Señora de las Angustias on a cloth, they encountered the Opata, who could not pronounce Señora, instead saying Sonora. A third theory, written by Father Cristóbal de Cañas in 1730, states that the name comes from the word for a natural water well, which the Spaniards modified to "Sonora".
The first record of the name Sonora comes from explorer Francisco Vásquez de Coronado, who passed through the state in 1540 and called part of the area the Valle de la Sonora. Francisco de Ibarra traveled through the area in 1567 and referred to the Valles de Señora; the literal meaning of "sonora" in Spanish is "sonorous" or "loud." Evidence of human existence in the state dates back over 10,000 years, with some of the best-known remains at the San Dieguito Complex in the El Pinacate Desert. The first humans were nomadic hunter gatherers who used tools made from stones and wood. During much of the prehistoric period, the environmental conditions were less severe than they are today, with similar but more dense vegetation spread over a wider area; the oldest Clovis culture site in North America is believed to be El Fin del Mundo in northwestern Sonora. It was discovered during a 2007 survey, it features occupation dating around 13,390 calibrated years BP. In 2011, remains of Gomphothere were found.
Agriculture first appeared around 400 200 CE in the river valleys. Remains of ceramics have been found dating from 750 CE with diversification from 800 and 1300 CE Between 1100 and 1350, the region had complex small villages with well-developed trade networks; the lowland central coast, seems never to have adopted agriculture. Because Sonora and much of the northwest does not share many of the cultural traits of that area, it is not considered part of Mesoamerica. Though evidence exists of trade between the peoples of Sonora and Mesoamerica, Guasave in Sinaloa is the most north-westerly point considered Mesoamerican. Three archaeological cultures developed in the low, flat areas of the state near the coast: the Trincheras tradition, the Huatabampo tradition, the Central Coast tradition; the Trincheras tradition is dated to between 750 and 1450 CE and known from sites in the Altar and Concepción valleys, but its range extended from the Gulf of California into northern Sonora. The tradition is named after trenches found in a number of sites, the best known of, the Cerro de Trincheras.
The Huatabampo tradition is centered south of the Trincheras along the coast, with sites along extinct lagoons and river valleys. This tradition has a distinctive ceramic complex. Huatabampo culture shows similarities with the Chametla to the Hohokam to the north; this ended around 1000 CE. Unlike the other two traditions, the Central Coast remained a hunter-gatherer culture, as the area lacks the resources for agriculture; the higher elevations of the state were dominated by the Casas Grandes and Río Sonora tradition. The Río Sonora culture is located in central Sonora from the border area to modern Sinaloa. A beginning date for this culture has not been determined but it disappeared by the early 14th century; the Casas Grandes tradition in Sonora was an extension of the Río Sonora tradition based in the modern state of Chihuahua, which exterted its influence down to parts of the Sonoran coast. Climatic changes in the middle of the 15th century resulted in the increased desertification of northwest Mexico in general.
This is the probable cause for the drastic decrease in the number and size of settlements starting around this time. The peoples that remained in the area reverted to a less complex social organiz
Gulf of California
The Gulf of California is a marginal sea of the Pacific Ocean that separates the Baja California Peninsula from the Mexican mainland. It is bordered by the states of Baja California, Baja California Sur and Sinaloa with a coastline of 4,000 km. Rivers which flow into the Gulf of California include the Colorado, Mayo, Sinaloa and the Yaqui; the gulf's surface area is about 160,000 km2. Depths range from fording at the estuary near Yuma, Arizona, to in excess of 3,000 meters in the deepest parts; the Gulf is thought to be one of the most diverse seas on the planet, is home to more than 5,000 species of micro-invertebrates. Home to over a million people, Baja California is the second-longest peninsula in the world, after the Malay Peninsula in Southeast Asia. Parts of the Gulf of California are a UNESCO World Heritage Site. AreaThe International Hydrographic Organization defines the southern limit of the Gulf of California as: "A line joining Piastla Point in Mexico, the southern extreme of Lower California".
The Gulf of California is 1,126 km long and 48–241 km wide, with an area of 177,000 km2, a mean depth of 818.08 m, a volume of 145,000 km3. The Gulf of California includes three faunal regions: the Northern Gulf of California the Central Gulf of California the Southern Gulf of CaliforniaOne recognized transition zone is termed the Southwestern Baja California Peninsula. Transition zones exist between faunal regions, they vary for each individual species. Geology Geologic evidence is interpreted by geologists as indicating the Gulf of California came into being around 5.3 million years ago as tectonic forces rifted the Baja California Peninsula off the North American Plate. As part of this process, the East Pacific Rise propagated up the middle of the Gulf along the seabed; this extension of the East Pacific Rise is referred to as the Gulf of California Rift Zone. The Gulf would extend as far as Indio, except for the tremendous delta created by the Colorado River; this delta blocks the sea from flooding the Imperial Valleys.
Volcanism dominates the East Pacific Rise. The island of Isla Tortuga is one example of this ongoing volcanic activity. Furthermore, hydrothermal vents due to extension tectonic regime, related to the opening of the Gulf of California, are found in the Bahía de Concepción, Baja California Sur. Islands The Gulf of California contains 37 major islands – the two largest being Isla Ángel de la Guarda and Tiburón Island. Most of the islands are found on the peninsular side of the gulf. In fact, many of the islands of the Sea of Cortez are the result of volcanic explosions that occurred during the early history of Baja California; the islands of Islas Marías, Islas San Francisco, Isla Partida are thought to be the result of such explosions. The formations of the islands, are not dependent on each other, they were each formed as a result of an individual structural occurrence. Several islands, including Isla Coronados, are home to volcanoes; the gulf has islands which together total about 420 hectares.
All of them as a whole were enacted as "Area Reserve and Migratory Bird Refuge and Wildlife" on August 2, 1978. In June 2000, the islands were given a new category "Protection Area Wildlife". In addition to this effort by the Mexican government, for its importance and recognition worldwide, all islands in the Gulf of California are part of the international program "Man and Biosphere" and are part of the World Reserve Network UNESCO Biosphere as Special Biosphere Reserve. Due to the vast expanse covered by this federal protected area conservation and management is carried out through a system of four regional directorates by way of co-direction. There is a regional directorate in the states of Baja California, Baja California Sur and Sinaloa. Notwithstanding the foregoing, the work of direct and indirect conservation is done in the islands is governed by a single Management Program, published in 2000, complemented by local and specific management programs archipelagos; the Directorate of Protection Area Wildlife California Gulf Islands in Baja California is responsible for 56 islands located off the coast of the state.
These are grouped into four archipelagos: San Luis Gonzaga or Enchanted, Guardian Angel, Bahia de los Angeles and San Lorenzo. Shores and tidesThe three general types of shores found in the Gulf of California include rocky shore, sandy beach, tidal flat; some of the rich biodiversity and high endemism that characterize the Gulf of California and make it such a hotspot for fishing can be attributed to insignificant factors, such as the types of rocks that make up a shore. Beaches with softer, more porous rocks have a higher species richness than those with harder, smoother rocks. Porous rocks will have more cracks and crevices in them, making them ideal living spaces for many animals; the rocks themselves, however need to be stable on the shore for a habitat to be stable. Additionally, the color of the rocks can affect the organisms living on a shore. For example, darker rocks will be warmer than lighter ones, can deter animals that do not have a high tolerance for heat. The
Little Colorado River
The Little Colorado River is a tributary of the Colorado River in the U. S. state of Arizona, providing the principal drainage from the Painted Desert region. Together with its major tributary, the Puerco River, it drains an area of about 26,500 square miles in eastern Arizona and western New Mexico. Although it stretches 340 miles, only the headwaters and the lowermost reaches flow year-round. Between St. Johns and Cameron, most of the river is a wide, braided wash, only containing water after heavy snowmelt or flash flooding; the lower 57.2 miles is known as the Little Colorado River Gorge and forms one of the largest arms of the Grand Canyon, at over 3,000 feet deep where it joins the Colorado near Desert View in Grand Canyon National Park. The river rises in Apache County; the West Fork starts in a valley on the north flank of Mount Baldy at an elevation of nearly 10,000 feet, while the East Fork starts nearby. The forks meet in a canyon near the town of Greer, it flows into River Reservoir leaves the canyon near Eagar.
The river turns north, meandering through Richville Valley, before emptying into Lyman Lake, impounded by an irrigation dam built in 1912. From there the river continues north, past the town of St. Johns. Shortly afterwards, the river transforms from a perennial stream to an ephemeral wash as it travels northwestwards through Hunt Valley, where it receives the Zuni River receiving Silver Creek and the Puerco River—its main tributaries—near the town of Holbrook as it flows into the Painted Desert; the Little Colorado passes Joseph City and crosses the Southern Transcon route of the BNSF Railway, now winding north into Coconino County. The river enters the Navajo Nation, drops over the 185-foot Grand Falls of the Little Colorado shortly after. Below Grand Falls, the river flows through a rugged canyon for about 15 miles. Emerging into the desert again, the Little Colorado skirts the eastern edge of Wupatki National Monument and passes the town of Cameron, where it is bridged by U. S. Highway 89.
From Cameron, the Little Colorado River carves an steep and narrow gorge into the Colorado Plateau achieving a maximum depth of about 3,200 feet. The depth of the canyon is such that groundwater is forced to the surface, forming numerous springs that restore a perennial river flow, it joins the Colorado deep inside miles from any major settlement. The confluence marks the end of the Marble Canyon segment of the Grand Canyon and the beginning of Upper Granite Gorge; the Little Colorado River is one of the two major tributaries of the Colorado River in Arizona, the other being the Gila River. Runoff peaks twice a year, first in the early spring from snow melt and highland rain; the annual runoff is variable with the possibility of no flow occurring due to a weak snow pack or lack of summer rain. Conversely, years such as 1949, 1973, 1979, 1983 and 1993 have seen massive volumes of spring snowmelt while large monsoon runoff has occurred in 1955, 1964, 1984 and 2006. Monthly average flows in the springtime average several hundred cfs and can reach 2,000 to 3,000 cubic feet per second.
Only the upper reaches of the river above St. Johns, the lowermost stretch below Cameron, flow year round. According to a streamflow gauge near Cameron, before the river enters the Grand Canyon, the river's average annual flow was 367.2 cubic feet per second from 1948 to present. The highest annual average was 1,127 cubic feet per second in 1973, the lowest was 14.1 cubic feet per second in 2000. The river's peak flows can be far higher than its average flow, because of quick desert runoff from cloudbursts. At the same gauge, peak flows were recorded from 1923 to 2008, with spotty data from 1924 to 1947; the highest recorded peak was 120,000 cubic feet per second on September 20, 1923, while the lowest was 1,590 cubic feet per second in 1974. Human activity in the Little Colorado River watershed dates back to the early Holocene epoch, in the last glacial period. Nomadic hunter-gatherers inhabited the water-rich and diverse upper basin of the Little Colorado for 8,000 years before the Navajo and Hopi tribes populated the area.
Many of these people practiced small-scale irrigation in riverside villages, located in sheltered canyons and cliffs that provided defense. Early Spanish explorers exploring the Grand Canyon area were most the first Europeans to see the Little Colorado River, they called it the Little Colorado. Other than fur trappers and mountain men, one of the first organized expeditions into the area of the Little Colorado River was led by Amiel Weeks Whipple in 1853–54 during one of the expeditions to map out a route for a transcontinental railroad. Called The Great Railroad Expeditions, or Pacific Railroad Surveys, Whipple's expedition consisted of several teams going along the 35th parallel from Albuquerque to the Pacific, following the Santa Fe Trail route; the Little Colorado River known as the Flax River, the first Rio Chiquito, is depicted and labelled as such on a map compiled by Lt. Joseph C. Ives and published in the official volumes of those expeditions. Ives would again return to the area in 1858 after navigating a steamboat named the Explorer up the Colorado from south of Yuma northwards to Black Canyon, at which point his party went
The Colorado Plateau known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus centered on the Four Corners region of the southwestern United States. This province covers an area of 336, 700 km2 within western Colorado, northwestern New Mexico and eastern Utah, northern Arizona. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, Little Colorado. Most of the remainder of the plateau is drained by its tributaries; the Colorado Plateau is 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. 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, fins, river narrows, natural bridges, 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 units in the country outside the Washington, DC metropolitan area. Among its nine National Parks are Grand Canyon, Bryce Canyon, Capitol Reef, Arches, Mesa Verde, Petrified Forest. Among its 18 National Monuments are Bears Ears, Rainbow Bridge, Hovenweep, Sunset Crater Volcano, Grand Staircase-Escalante, Natural Bridges, Canyons of the Ancients, Chaco Culture National Historical Park and the Colorado National Monument; this province is bounded by the Rocky Mountains in Colorado, by the Uinta Mountains and Wasatch Mountains branches of the Rockies in northern and central Utah. It is 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: Uinta Basin Section High Plateaus Section Grand Canyon Section Canyon Lands Section Navajo Section Datil SectionAs the name implies, the High Plateaus Section is, on average, the highest section.
North-south trending normal faults that include the Hurricane, Grand Wash, 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, the Paradox Basin were created by movement along structural weaknesses in the region's oldest rock. In Utah, the province includes several higher fault-separated plateaus: Awapa Plateau Aquarius Plateau Kaiparowits Plateau Markagunt Plateau Paunsaugunt Plateau Sevier Plateau Fishlake Plateau Pavant Plateau Gunnison Plateau and the Tavaputs Plateau.
Some sources include the Tushar Mountain Plateau as part of the Colorado Plateau, but others do not. The flat-lying sedimentary rock units that make up these plateaus are found in component plateaus that are between 4,900 to 11,000 feet above sea level. A supersequence of these rocks is exposed in the various cliffs and canyons that make up the Grand Staircase. 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, the Pink Cliffs. Within these rocks are abundant mineral resources that include uranium, coal and natural gas. Study of the area's unusually clear geologic history has 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 of annual precipitation. Higher areas receive more precipitation and are covered in forests of pine and spruce.
Though it can be said that the Plateau 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, half east of it; the Ancestral Puebloan People lived in the region from 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. 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 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.
Reduced sediment load changed its color from reddish brown t
Horseshoe Bend (Arizona)
Horseshoe Bend is a horseshoe-shaped incised meander of the Colorado River located near the town of Page, Arizona, in the United States. Horseshoe Bend is located 5 miles downstream from the Glen Canyon Dam and Lake Powell within Glen Canyon National Recreation Area, about 4 miles southwest of Page, it is accessible via hiking a 1.5-mile round trip from U. S. Route 89. Horseshoe Bend can be viewed from the steep cliff above; the overlook is 4,200 feet above sea level, the Colorado River is at 3,200 feet above sea level, making it a 1,000-foot drop. The rock walls of Horseshoe Bend contain hematite, platinum and other minerals. By 2018 references to the location on social media had caused the number of visitors to increase significantly. Official website