Nevada is a state in the Western United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast and Utah to the east. Nevada is the 7th most extensive, the 32nd most populous, but the 9th least densely populated of the U. S. states. Nearly three-quarters of Nevada's people live in Clark County, which contains the Las Vegas–Paradise metropolitan area where three of the state's four largest incorporated cities are located. Nevada's capital, however, is Carson City. Nevada is known as the "Silver State" because of the importance of silver to its history and economy, it is known as the "Battle Born State", because it achieved statehood during the Civil War. Nevada is desert and semi-arid, much of it within the Great Basin. Areas south of the Great Basin are within the Mojave Desert, while Lake Tahoe and the Sierra Nevada lie on the western edge. About 86% of the state's land is managed by various jurisdictions of the U. S. federal government, both civilian and military.
Before European contact, Native Americans of the Paiute and Washoe tribes inhabited the land, now Nevada. The first Europeans to explore the region were Spanish, they called the region Nevada because of the snow. The area formed part of the Viceroyalty of New Spain, became part of Mexico when it gained independence in 1821; the United States annexed the area in 1848 after its victory in the Mexican–American War, it was incorporated as part of Utah Territory in 1850. The discovery of silver at the Comstock Lode in 1859 led to a population boom that became an impetus to the creation of Nevada Territory out of western Utah Territory in 1861. Nevada became the 36th state on October 31, 1864, as the second of two states added to the Union during the Civil War. Nevada has a reputation for its libertarian laws. In 1940, with a population of just over 110,000 people, Nevada was by far the least-populated state, with less than half the population of the next least-populated state. However, legalized gambling and lenient marriage and divorce laws transformed Nevada into a major tourist destination in the 20th century.
Nevada is the only U. S. state where prostitution is legal, though it is illegal in Clark County, Washoe County and Carson City. The tourism industry remains Nevada's largest employer, with mining continuing as a substantial sector of the economy: Nevada is the fourth-largest producer of gold in the world; the name "Nevada" comes from meaning "snow-covered", after the Sierra Nevada. Most Nevadans pronounce the second syllable of their state name using the TRAP vowel. Many from outside the Western United States pronounce it with the PALM vowel. Although the latter pronunciation is closer to the Spanish pronunciation, it is not the pronunciation preferred by most Nevadans. State Assemblyman Harry Mortenson proposed a bill to recognize the alternate pronunciation of Nevada, though the bill was not supported by most legislators and never received a vote; the Nevadan pronunciation is the de facto official one, since it is the one used by the state legislature. At one time, the state's official tourism organization, TravelNevada, stylized the name of the state as "Nevăda", with a breve mark over the a indicating the locally preferred pronunciation, available as a license plate design.
Nevada is entirely within the Basin and Range Province, is broken up by many north-south mountain ranges. Most of these ranges have endorheic valleys between them, which belies the image portrayed by the term Great Basin. Much of the northern part of the state is within the Great Basin, a mild desert that experiences hot temperatures in the summer and cold temperatures in the winter. Moisture from the Arizona Monsoon will cause summer thunderstorms; the state's highest recorded temperature was 125 °F in Laughlin on June 29, 1994. The coldest recorded temperature was −52 °F set in San Jacinto in 1972, in the northeastern portion of the state; the Humboldt River crosses the state from east to west across the northern part of the state, draining into the Humboldt Sink near Lovelock. Several rivers drain from the Sierra Nevada eastward, including the Walker and Carson rivers. All of these rivers are endorheic basins, ending in Walker Lake, Pyramid Lake, the Carson Sink, respectively. However, not all of Nevada is within the Great Basin.
Tributaries of the Snake River drain the far north, while the Colorado River, which forms much of the boundary with Arizona, drains much of southern Nevada. The mountain ranges, some of which have peaks above 13,000 feet, harbor lush forests high above desert plains, creating sky islands for endemic species; the valleys are no lower in elevation than 3,000 feet, while some in central Nevada are above 6,000 feet. The southern third of the state, where the Las Vegas area is situated, is within the Mojave Desert; the area is closer to the Arizona Monsoon in the summer. The terrain is lower below 4,000 feet, creating conditions for hot summer days and cool to chilly winter nights. Nevada and California have by far the longest diagonal line as a state boundary at just over 400 miles; this line begins in Lake Tahoe nearly
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic rock is artificial, in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is applied to what are metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "volcaniclastics," and these are technically sedimentary rocks. Volcanic rocks are among the most common rock types on Earth's surface in the oceans. On land, they are common at plate boundaries and in flood basalt provinces, it has been estimated. Lava Tephra Volcanic bomb Lapilli Volcanic ash Volcanic rocks are fine-grained or aphanitic to glass in texture, they contain clasts of other rocks and phenocrysts.
Phenocrysts are crystals that are identifiable with the unaided eye. Rhomb porphyry is an example with large rhomb shaped phenocrysts embedded in a fine grained matrix. Volcanic rocks have a vesicular texture caused by voids left by volatiles trapped in the molten lava. Pumice is a vesicular rock produced in explosive volcanic eruptions. Most modern petrologists classify igneous rocks, including volcanic rocks, by their chemistry when dealing with their origin; the fact that different mineralogies and textures may be developed from the same initial magmas has led petrologists to rely on chemistry to look at a volcanic rock's origin. The chemistry of volcanic rocks is dependent on two things: the initial composition of the primary magma and the subsequent differentiation. Differentiation of most volcanic rocks tends to increase the silica content by crystal fractionation; the initial composition of most volcanic rocks is basaltic, albeit small differences in initial compositions may result in multiple differentiation series.
The most common of these series are tholeiitic, calc-alkaline, alkaline. Most volcanic rocks share a number of common minerals. Differentiation of volcanic rocks tends to increase the silica content by fractional crystallization. Thus, more evolved volcanic rocks tend to be richer in minerals with a higher amount of silica such as phyllo and tectosilicates including the feldspars, quartz polymorphs and muscovite. While still dominated by silicates, more primitive volcanic rocks have mineral assemblages with less silica, such as olivine and the pyroxenes. Bowen's reaction series predicts the order of formation of the most common minerals in volcanic rocks. A magma may pick up crystals that crystallized from another magma. Diamonds found in kimberlites are well-known xenocrysts. Volcanic rocks are named according to both texture. Basalt is a common volcanic rock with low silica content. Rhyolite is a volcanic rock with high silica content. Rhyolite has silica content similar to that of granite while basalt is compositionally equal to gabbro.
Intermediate volcanic rocks include andesite, dacite and latite. Pyroclastic rocks are the product of explosive volcanism, they are felsic. Pyroclastic rocks are the result of volcanic debris, such as ash and tephra, other volcanic ejecta. Examples of pyroclastic rocks are ignimbrite. Shallow intrusions, which possess structure similar to volcanic rather than plutonic rocks, are considered to be volcanic, shading into subvolcanic; the terms lava stone and lava rock are more used by marketers than geologists, who would say "volcanic rock". "Lava stone" may describe anything from a friable silicic pumice to solid mafic flow basalt, is sometimes used to describe rocks that were never lava, but look as if they were. To convey anything about the physical or chemical properties of the rock, a more specific term should be used; the sub-family of rocks that form from volcanic lava are called igneous volcanic rocks. The lavas of different volcanoes, when cooled and hardened, differ much in their appearance and composition.
If a rhyolite lava-stream cools it can freeze into a black glassy substance called obsidian. When filled with bubbles of gas, the same lava may form the spongy appearing pumice. Allowed to cool it forms a light-colored, uniformly solid rock called rhyolite; the lavas, having cooled in contact with the air or water, are finely crystalline or have at least fine-grained ground-mass representing that part of the viscous semi-crystalline lava flow, still liquid at the moment of eruption. At this time they were exposed only to atmospheric pressure, the steam and other gases, which they contained in great quantity were free to escape; as crystal
Wyoming is a state in the mountain region of the western United States. The state is the 10th largest by area, the least populous, the second most sparsely populated state in the country. Wyoming is bordered on the north by Montana, on the east by South Dakota and Nebraska, on the south by Colorado, on the southwest by Utah, on the west by Idaho and Montana; the state population was estimated at 577,737 in 2018, less than 31 of the most populous U. S. cities including Denver in neighboring Colorado. Cheyenne is the state capital and the most populous city, with an estimated population of 63,624 in 2017; the western two-thirds of the state is covered by the mountain ranges and rangelands of the Rocky Mountains, while the eastern third of the state is high elevation prairie called the High Plains. Half of the land in Wyoming is owned by the U. S. government, leading Wyoming to rank sixth by area and fifth by proportion of a state's land owned by the federal government. Federal lands include two national parks—Grand Teton and Yellowstone—two national recreation areas, two national monuments, several national forests, historic sites, fish hatcheries, wildlife refuges.
Original inhabitants of the region include the Crow, Arapaho and Shoshone. Southwestern Wyoming was in the Spanish Empire and Mexican territory until it was ceded to the United States in 1848 at the end of the Mexican–American War; the region acquired the name Wyoming when a bill was introduced to the U. S. Congress in 1865 to provide a "temporary government for the territory of Wyoming"; the name was used earlier for the Wyoming Valley in Pennsylvania, is derived from the Munsee word xwé:wamənk, meaning "at the big river flat". The main drivers of Wyoming's economy are mineral extraction—mostly coal, natural gas, trona—and tourism. Agricultural commodities include livestock, sugar beets and wool; the climate is semi-arid and continental and windier than the rest of the U. S. with greater temperature extremes. Wyoming has been a politically conservative state since the 1950s, with the Republican Party candidate winning every presidential election except 1964. Wyoming's climate is semi-arid and continental, is drier and windier in comparison to most of the United States with greater temperature extremes.
Much of this is due to the topography of the state. Summers in Wyoming are warm with July high temperatures averaging between 85 and 95 °F in most of the state. With increasing elevation, this average drops with locations above 9,000 feet averaging around 70 °F. Summer nights throughout the state are characterized by a rapid cooldown with the hottest locations averaging in the 50–60 °F range at night. In most of the state, most of the precipitation tends to fall in early summer. Winters are cold, but are variable with periods of sometimes extreme cold interspersed between mild periods, with Chinook winds providing unusually warm temperatures in some locations. Wyoming is a dry state with much of the land receiving less than 10 inches of rainfall per year. Precipitation depends on elevation with lower areas in the Big Horn Basin averaging 5–8 inches; the lower areas in the North and on the eastern plains average around 10–12 inches, making the climate there semi-arid. Some mountain areas do receive a good amount of precipitation, 20 inches or more, much of it as snow, sometimes 200 inches or more annually.
The state's highest recorded temperature is 114 °F at Basin on July 12, 1900 and the lowest recorded temperature is −66 °F at Riverside on February 9, 1933. The number of thunderstorm days vary across the state with the southeastern plains of the state having the most days of thunderstorm activity. Thunderstorm activity in the state is highest during early summer; the southeastern corner of the state is the most vulnerable part of the state to tornado activity. Moving away from that point and westwards, the incidence of tornadoes drops with the west part of the state showing little vulnerability. Tornadoes, where they occur, tend to be small and brief, unlike some of those that occur farther east; as specified in the designating legislation for the Territory of Wyoming, Wyoming's borders are lines of latitude 41°N and 45°N, longitude 104°3'W and 111°3'W, making the shape of the state a latitude-longitude quadrangle. Wyoming is one of only three states to have borders along only straight latitudinal and longitudinal lines, rather than being defined by natural landmarks.
Due to surveying inaccuracies during the 19th century, Wyoming's legal border deviates from the true latitude and longitude lines by up to half of a mile in some spots in the mountainous region along the 45th parallel. Wyoming is bordered on the north by Montana, on the east by South Dakota and Nebraska, on the south by Colorado, on the southwest by Utah, on the west by Idaho, it is the tenth largest state in the United States in total area, containing 97,814 square miles and is made up of 23 counties. From the north border to the south border it is 276 miles; the Great Plains meet the Rocky Mountains in Wyoming. The state is a great plateau broken by many mountain ranges. Surface elevations range from the summit of Gannett Peak in the Wind River Mountain Range, at 13,804 feet, to the Belle Fourche River val
Marble Canyon is the section of the Colorado River canyon in northern Arizona from Lee's Ferry to the confluence with the Little Colorado River, which marks the beginning of the Grand Canyon. Lee's Ferry is a common launching point for river runners starting their journey through the Grand Canyon. Marble Canyon is well known for the Navajo Bridge, where US Highway 89A crosses the Colorado River. Marble Canyon marks the western boundary of the Navajo Nation. In 1975, the former Marble Canyon National Monument, which followed the Colorado River northeast from the Grand Canyon to Lee's Ferry, was made part of Grand Canyon National Park; the name Marble Canyon is a misnomer. Although John Wesley Powell knew this when he named the canyon, he thought the polished limestone looked like marble. In his words, "The limestone of the canyon is polished, makes a beautiful marble. Sometimes the rocks are of many colors - white, gray and purple, with saffron tints." Marble Canyon is the site of one of the last great proposed dam projects on the Colorado, the Marble Canyon Dam.
Proposed and investigated in the early 1950s by the United States Bureau of Reclamation, the proposal met substantial opposition, notably from the Sierra Club, when a revived proposal was considered by the state of Arizona as part of the Central Arizona Project from 1965 to 1968. The proposed dam was abandoned in 1968. Exploratory holes, which were drilled in the Redwall Limestone of the canyon walls in an early phase of the abortive project, can still be seen at Mile 39.2. Marble Canyon is the only home of the endangered cactus Pediocactus bradyi
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