1.
Sedimentary basin
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Sedimentary basins are regions of Earth of long-term subsidence creating accommodation space for infilling by sediments. Sedimentary basins occur in diverse geological settings usually associated with tectonic activity. Basins formed in different plate tectonic regimes vary in their preservation potential, on oceanic crust, basins are likely to be subducted, while marginal continental basins may be partially preserved, and intracratonic basins have a high probability of preservation. As the sediments are buried, they are subjected to increasing pressure, a number of basins formed in extensional settings can undergo inversion which has accounted for a number of the economically viable oil reserves on earth which were formerly basins. Sedimentary basins form primarily in convergent, divergent and transform settings, convergent boundaries create foreland basins through tectonic compression of oceanic and continental crust during lithospheric flexure. Tectonic extension at divergent boundaries where continental rifting is occurring can create a nascent ocean basin leading to either an ocean or the failure of the rift zone. If the lithosphere is caused to stretch horizontally, by such as ridge-push or trench-pull. The lower, hotter part of the lithosphere will flow away from the main area being stretched, whilst the upper, cooler and more brittle crust will tend to fault. The combined effect of two mechanisms is for the Earths surface in the area of extension to subside, creating a geographical depression which is then often infilled with water and/or sediments. An example of a basin caused by lithospheric stretching is the North Sea – also an important location for significant hydrocarbon reserves, another such feature is the Basin and Range Province which covers most of the USA state of Nevada, forming a series of horst and graben structures. Another expression of lithospheric stretching results in the formation of basins with central ridges, The Red Sea is in fact an incipient ocean. The mouth of the Red Sea is also a triple junction where the Indian Ocean Ridge, Red Sea Rift. This is the place on the planet where such a triple junction in oceanic crust is exposed subaerially. The reason for this is twofold, due to a high thermal buoyancy of the junction, if a load is placed on the lithosphere, it will tend to flex in the manner of an elastic plate. The magnitude of the lithospheric flexure is a function of the load and the flexural rigidity of the lithosphere. Flexural rigidity is in itself, a function of the mineral composition, thermal regime. The nature of the load is varied, for instance, the Hawaiian Islands chain of volcanic edifices has sufficient mass to cause deflection in the lithosphere. Deformation of the lithosphere in the plane of the earth occurs as a result of near horizontal maximum and minimum principal stresses, the resulting zones of subsidence are known as strike-slip or pull-apart basins
2.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
3.
U.S. state
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A U. S. state is a constituent political entity of the United States of America. There are 50 states, which are together in a union with each other. Each state holds administrative jurisdiction over a geographic territory. Due to the shared sovereignty between each state and the government, Americans are citizens of both the federal republic and of the state in which they reside. State citizenship and residency are flexible, and no government approval is required to move between states, except for persons covered by certain types of court orders. States range in population from just under 600,000 to over 39 million, four states use the term commonwealth rather than state in their full official names. States are divided into counties or county-equivalents, which may be assigned some local authority but are not sovereign. County or county-equivalent structure varies widely by state, State governments are allocated power by the people through their individual constitutions. All are grounded in principles, and each provides for a government. States possess a number of powers and rights under the United States Constitution, Constitution has been amended, and the interpretation and application of its provisions have changed. The general tendency has been toward centralization and incorporation, with the government playing a much larger role than it once did. There is a debate over states rights, which concerns the extent and nature of the states powers and sovereignty in relation to the federal government. States and their residents are represented in the federal Congress, a legislature consisting of the Senate. Each state is represented in the Senate by two senators, and is guaranteed at least one Representative in the House, members of the House are elected from single-member districts. Representatives are distributed among the states in proportion to the most recent constitutionally mandated decennial census, the Constitution grants to Congress the authority to admit new states into the Union. Since the establishment of the United States in 1776, the number of states has expanded from the original 13 to 50, alaska and Hawaii are the most recent states admitted, both in 1959. The Constitution is silent on the question of states have the power to secede from the Union. Shortly after the Civil War, the U. S. Supreme Court, in Texas v. White, as a result, while the governments of the various states share many similar features, they often vary greatly with regard to form and substance
4.
Texas
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Texas is the second largest state in the United States by both area and population. Other major cities include Austin, the second most populous state capital in the U. S. Texas is nicknamed the Lone Star State to signify its former status as an independent republic, and as a reminder of the states struggle for independence from Mexico. The Lone Star can be found on the Texan state flag, the origin of Texass name is from the word Tejas, which means friends in the Caddo language. Due to its size and geologic features such as the Balcones Fault, although Texas is popularly associated with the U. S. southwestern deserts, less than 10 percent of Texas land area is desert. Most of the centers are located in areas of former prairies, grasslands, forests. Traveling from east to west, one can observe terrain that ranges from coastal swamps and piney woods, to rolling plains and rugged hills, the term six flags over Texas refers to several nations that have ruled over the territory. Spain was the first European country to claim the area of Texas, Mexico controlled the territory until 1836 when Texas won its independence, becoming an independent Republic. In 1845, Texas joined the United States as the 28th state, the states annexation set off a chain of events that caused the Mexican–American War in 1846. A slave state before the American Civil War, Texas declared its secession from the U. S. in early 1861, after the Civil War and the restoration of its representation in the federal government, Texas entered a long period of economic stagnation. One Texan industry that thrived after the Civil War was cattle, due to its long history as a center of the industry, Texas is associated with the image of the cowboy. The states economic fortunes changed in the early 20th century, when oil discoveries initiated a boom in the state. With strong investments in universities, Texas developed a diversified economy, as of 2010 it shares the top of the list of the most Fortune 500 companies with California at 57. With a growing base of industry, the leads in many industries, including agriculture, petrochemicals, energy, computers and electronics, aerospace. Texas has led the nation in export revenue since 2002 and has the second-highest gross state product. The name Texas, based on the Caddo word tejas meaning friends or allies, was applied by the Spanish to the Caddo themselves, during Spanish colonial rule, the area was officially known as the Nuevo Reino de Filipinas, La Provincia de Texas. Texas is the second largest U. S. state, behind Alaska, though 10 percent larger than France and almost twice as large as Germany or Japan, it ranks only 27th worldwide amongst country subdivisions by size. If it were an independent country, Texas would be the 40th largest behind Chile, Texas is in the south central part of the United States of America. Three of its borders are defined by rivers, the Rio Grande forms a natural border with the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the south
5.
New Mexico
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New Mexico is a state located in the southwestern region of the United States of America. It was admitted to the Union as the 47th state on January 6,1912 and it is usually considered one of the Mountain States. New Mexico is fifth by area, the 36th-most populous, inhabited by Native Americans for thousands of years before European exploration, New Mexico was colonized by the Spanish in 1598 Imperial Spanish viceroyalty of New Spain. Later, it was part of independent Mexico before becoming a U. S. territory and eventually a U. S. state as a result of the Mexican–American War. Among U. S. states, New Mexico has the highest percentage of Hispanics, the major Native American nations in the state are Navajo, Pueblo, and Apache peoples. The demography and culture of the state are shaped by these strong Hispanic and Native American influences and its scarlet and gold colors are taken from the royal standards of Spain, along with the ancient sun symbol of the Zia, a Pueblo-related tribe. New Mexico, or Nuevo México in Spanish, is incorrectly believed to have taken its name from the nation of Mexico. The name simply stuck, even though the area had no connection to Mexico or the Mexica Indian tribes, Mexico, formerly a part of New Spain, adopted its name centuries later in 1821, after winning independence from Spanish rule. New Mexico was a part of the independent Mexican Empire and Federal Republic of Mexico for 27 years,1821 through 1848, New Mexico and Mexico developed as neighboring Spanish-speaking communities under Spanish rule, with relatively independent histories. The states total area is 121,412 square miles, the eastern border of New Mexico lies along 103° W longitude with the state of Oklahoma, and 2.2 miles west of 103° W longitude with Texas. On the southern border, Texas makes up the eastern two-thirds, while the Mexican states of Chihuahua and Sonora make up the western third, the western border with Arizona runs along the 109°03 W longitude. The southwestern corner of the state is known as the Bootheel, the 37° N latitude parallel forms the northern boundary with Colorado. The states New Mexico, Colorado, Arizona, and Utah come together at the Four Corners in the corner of New Mexico. New Mexico, although a state, has very little water. Its surface water area is about 250 square miles, the New Mexican landscape ranges from wide, rose-colored deserts to broken mesas to high, snow-capped peaks. Despite New Mexicos arid image, heavily forested mountain wildernesses cover a significant portion of the state, the Sangre de Cristo Mountains, the southernmost part of the Rocky Mountains, run roughly north-south along the east side of the Rio Grande in the rugged, pastoral north. The most important of New Mexicos rivers are the Rio Grande, Pecos, Canadian, San Juan, the Rio Grande is tied for the fourth-longest river in the United States. Tourists visiting these sites bring significant money to the state, other areas of geographical and scenic interest include Kasha-Katuwe Tent Rocks National Monument and the Gila Wilderness in the southwest of the state
6.
Lubbock, Texas
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Lubbock is a city in and the county seat of Lubbock County, Texas, United States. The city is located in the part of the state. According to a 2015 Census estimate, Lubbock had a population of 249,042, making it the 83rd most populous city in the United States of America and the 11th most populous city in the state of Texas. The city is the center of the Lubbock metropolitan area. The area is the largest contiguous cotton-growing region in the world and is dependent on water drawn from the Ogallala Aquifer for irrigation. Lubbock was selected as the 12th best place to start a business by CNNMoney. com. CNN mentioned the traditional business atmosphere, low rent for commercial space, central location. Lubbock is home to Texas Tech University, the sixth-largest college by enrollment in the state, Lubbock High School has been recognized for three consecutive years by Newsweek as one of the top high schools in the United States based in part on its international baccalaureate program. Lubbock County was founded in 1876 and it was named after Thomas Saltus Lubbock, former Texas Ranger and brother of Francis Lubbock, governor of Texas during the Civil War. As early as 1884, a federal post office existed in Yellow House Canyon, a small town, known as Old Lubbock, Lubbock, or North Town, was established about three miles to the east. In 1890, the original Lubbock merged with Monterey, another small town south of the canyon, the new town adopted the Lubbock name. The merger included moving the original Lubbocks Nicolett Hotel across the canyon on rollers to the new townsite, Lubbock became the county seat in 1891, and was incorporated on March 16,1909. In the same year, the first railroad train arrived, Texas Technological College was founded in Lubbock in 1923. A separate university, Texas Tech University Health Sciences Center, opened as Texas Tech University School of Medicine in 1969, both universities are now overseen by the Texas Tech University System, after it was established in 1996 and based in Lubbock. Lubbock Christian University, founded in 1957, and Sunset International Bible Institute, South Plains College and Wayland Baptist University operate branch campuses in Lubbock. At one time, Lubbock was home to Reese Air Force Base located 6 miles west of the city, the bases primary mission throughout its existence was pilot training. The base was closed 30 September 1997 after being selected for closure by the Base Realignment and Closure Commission in 1995 and is now a research, the city is home to the Lubbock Lake Landmark, part of the Museum of Texas Tech University. The landmark is an archaeological and natural preserve at the northern edge of the city
7.
Midland, Texas
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Midland is a city in and the county seat of Midland County, Texas, United States, on the Southern Plains of the states western area. A small portion of the city extends into Martin County, at the 2010 census, the population of Midland was 111,147, and a 2015 estimate gave a total of 132,950, making it the twenty-fourth most populous city in the state of Texas. Due to the oil boom in Midland, certain officials have given population estimates above 155,000, the metropolitan area is also a component of the larger Midland−Odessa, Texas Combined Statistical Area, which had an estimated population of 295,987 on July 1,2012. People in Midland are called Midlanders, Midland was founded as the midway point between Fort Worth and El Paso on the Texas and Pacific Railroad in 1881. It is the hometown of former First Lady Laura Bush, and the home of former Presidents George H. W. Bush and George W. Bush. Midland was established in June 1881 as Midway Station, on the Texas, Midland became the county seat of Midland County in March 1885, when that county was first organized and separated from Tom Green County. By 1890, it had one of the most important cattle shipping centers in the state. The city was incorporated in 1906, and by 1910 the city established its first fire department, soon, Midland was transformed into the administrative center of the West Texas oil fields. During the Second World War, Midland was the largest bombardier training base in the country, a second boom period began after the war, with the discovery and development of the Spraberry Trend, still ranked as the third-largest oil field in the United States by total reserves. Yet another boom period took place during the 1970s, with the oil prices associated with the oil. Today, the Permian Basin produces one fifth of the total petroleum. Midlands economy still relies heavily on petroleum, however, the city has diversified to become a regional telecommunications. By August 2006, a period of crude oil production had caused a significant workforce deficit. According to the Midland Chamber of Commerce, at that time there were almost 2,000 more jobs available in the Permian Basin than there were workers to fill them, John Howard Griffin wrote a history of Midland in 1959, Land of the High Sky. In 1967, the U. S. Supreme Court heard the case of Avery v. Midland County, Midland mayor Hank Avery had sued Midland County, challenging the electoral-districting scheme in effect for elections to the County Commissioners Court. The county districts geographically quartered the county, but the city of Midland, in the northwestern quarter, the majority of the U. S. Supreme Court held that the districting inequality violated the Fourteenth Amendments Equal Protection clause. The dissenting minority held that this example of the Warren Courts policy of incorporation at the local-government level exceeded the Courts constitutional authority, Midland is located at 32°0′N 102°6′W, in the Permian Basin in the plains of West Texas. According to the United States Census Bureau, the city has an area of 71.5 square miles
8.
Odessa, Texas
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Odessa /ˌoʊˈdɛsə/ is a city in and the county seat of Ector County, Texas, United States. It is located primarily in Ector County, although a portion of the city extends into Midland County. Odessas population was 118,918 at the 2010 census making it the 29th-most populous city in Texas and it is the principal city of the Odessa Metropolitan Statistical Area, which includes all of Ector County. In 2014, Forbes magazine ranked Odessa as the third fastest-growing small city in the United States, Odessa is said to have been named after Odessa, Ukraine, because of the local shortgrass prairies resemblance to Ukraines steppe landscape. Odessa was founded in 1881 as a stop and cattle-shipping point on the Texas. The first post office opened in 1885, Odessa became the county seat of Ector County in 1891 when the county was first organized. It was incorporated as a city in 1927, after oil was discovered in Ector County on the Connell Ranch southwest of Odessa, with the opening of the Penn Field in 1929, and the Cowden Field in 1930, oil became a major draw for new residents. In 1925, the population was just 750, by 1929, for the rest of the twentieth century the citys population and economy grew rapidly during each of a succession of oil booms, often with accompanying contractions during the succeeding busts. Odessa is well known for its Kiss and Kill Murder in March 1961, betty Williams, an Odessa native, was murdered by Mack Herring because he claimed she begged him to. Her body was discovered in a pond several miles outside Odessa. Mack Herring was tried and acquitted for temporary insanity, in 2013, Odessa had the highest rate of violent crime in Texas, with 806.4 crimes per 100,000 inhabitants. Odessa is located along the edge of the Llano Estacado in West Texas. It is situated above the Permian Basin, a sedimentary deposit that contains significant reserves of oil. According to the United States Census Bureau, the city has an area of 44.0 square miles. 43.9 square miles of it is land and 0.1 square miles of it is covered by water, Odessa has the semiarid climate typical of West Texas. Summers are hot and sunny, while winters are mild and dry, most rainfall occurs in late spring and summer, snowfall is rare. The area exhibits a diurnal temperature range and frequent high winds. As of the census of 2010,99,940 people,35,216 households, the population density was 2,276.5 people per square mile
9.
Rock (geology)
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Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites
10.
Permian
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The Permian is a geologic period and system which spans 46.7 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic Period 252.2 Mya. It is the last period of the Paleozoic Era, the following Triassic Period belongs to the Mesozoic Era, the concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm. The Permian witnessed the diversification of the early amniotes into the groups of the mammals, turtles, lepidosaurs. The world at the time was dominated by two known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior, amniotes, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. The Permian ended with the Permian–Triassic extinction event, the largest mass extinction in Earths history, in which nearly 90% of marine species and it would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian-Triassic extinction event was protracted, on land, the term Permian was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil, the region now lies in the Perm Krai of Russia. This could have in part caused the extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms. During the Permian, all the Earths major landmasses were collected into a supercontinent known as Pangaea. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, a new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic Era. Large continental landmass interiors experience climates with extreme variations of heat and cold, deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees appeared in the Permian, the climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an Ice Age, glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continents interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles, Permian marine deposits are rich in fossil mollusks, echinoderms, and brachiopods. By the close of the Permian, trilobites and a host of other groups became extinct. Terrestrial life in the Permian included diverse plants, fungi, arthropods, the period saw a massive desert covering the interior of Pangaea
11.
Delaware Basin
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The Delaware Basin is a geologic depositional and structural basin in West Texas and southern New Mexico, famous for holding large oil fields and for a fossilized reef exposed at the surface. Guadalupe Mountains National Park and Carlsbad Caverns National Park protect part of the basin and it is part of the larger Permian Basin, itself contained within the Mid-Continent oil province. By earliest Permian time, during the Wolfcampian Epoch, the ovoid shaped subsiding Delaware Basin extended over 10,000 square miles in what is now western Texas and this period of deposition left a thickness of 1600 to 2200 feet of limestone interbedded with dark-colored shale. A narrow outlet that geologists call the Hovey Channel periodically supplied new seawater from the Panthalassa Ocean to the west, the somewhat smaller and shallower Midland Basin was just east and the much smaller Marfa Basin was to the southwest. All three basins were south of the equator, north of the Ouachita Mountains of mid-Texas, the Ouachita Mountains formed a rainshadow over the basins, and a warm shallow sea flooded the surrounding area. On the other side of the equator, the Ancestral Rocky Mountains formed a large mountainous island, the Delaware Basin temporarily stopped subsiding in the Leonardian Epoch at the start of the mid-Permian. Small banks along its margin developed along with small discontinuous patch reefs in the water just offshore. The first formation that resulted was the Yeso and consists of alternating beds of limestone, gypsum. The sediments responsible for creating the Yeso were deposited in areas that graded into the carbonate banks of the Victorio Peak Formation in the deeper waters. Thin-bedded limestones of the Bone Spring Formation accumulated as limy ooze in the stagnant deepest part of the basin, subsidence of the Delaware Basin restarted later in the mid Permian and by the Guadalupian Epoch of the upper Permian the patch reefs had grown larger. Rapid subsidence of the started in the middle Guadalupian. Patch reefs responded by rapid growth, resulting in the Goat Seep Reef, three facies developed, Sediments deposited in a lagoon, forming the sandstones and dolomites of the Queen and Grayburg Formations. Sponge and algae skeletons accumulated near the Goat Seep Reef to become the Getaway Bank, quartz sand laid down further in the basin became the Cherry Canyon Formation. Subsidence of the basin stopped for good by the part of the Guadalupian. Capitan Reef was the largest in the basin, and it rapidly grew 350 miles around it, the facies were, Fine-grained sand and carbonates deposited near the shore became the dolomites and sandstone of the Carlsbad Group. Offshore accumulations of sand and limey ooze in the basin were lithified into sandstone and limestone belonging to the Bell Canyon Formation, the Capitan Formation consists of Capitan Reef and is made of reef limestone. Capitan Reef was built primarily from calcareous sponges, encrusting algae such as stromatolites, in stark contrast, Cenozoic, Mesozoic, and even middle Paleozoic reefs are mainly composed of corals. Sea level dropped as the late Permian glaciation intensified and locked increasing amounts of water in distant ice caps, sedimentation continued to fill the Delaware Basin into the Ochoan Epoch of the upper Permian, periodically cutting the basin off from its source of seawater
12.
Marfa, Texas
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Marfa is a city in the high desert of the Trans-Pecos in far West Texas, located between the Davis Mountains and Big Bend National Park. It is the county seat of Presidio County, and its population as of the 2010 United States Census was 1,981. The city was founded in the early 1880s as a waterstop, the population increased during World War II, today, Marfa is a tourist destination and a major center for Minimalist art. Attractions include Building 98, the Chinati Foundation, artisan shops, historical architecture, a classic Texas town square, modern art installments, art galleries, Marfa was founded in the early 1880s as a railroad water stop. The town was named Marfa at the suggestion of the wife of a railroad executive, the town grew quickly during the 1920s. The Marfa Army Airfield served as a facility for several thousand pilots during World War II, including the American actor Robert Sterling. The base was used as the training ground for many of the United States Armys chemical mortar battalions. Marfa is located at 30°18′43″N 104°1′29″W, according to the United States Census Bureau, the town has a total area of 1.6 sq mi, all land. The city is located in the Chihuahuan Desert, a developed region of about 140,000 square miles. As of the 2010 United States Census,1,981 people,864 households, the population density was 1,354.6 people per square mile. There were 1,126 housing units at a density of 719.1 per square mile. The racial makeup of the city was 91% White,0. 28% African American,0. 38% Native American,0. 05% Asian,7. 50% from other races, hispanics or Latinos of any race were 69. 9% of the population. About 31. 4% of all households were made up of individuals, the average household size was 2.35 and the average family size was 2.99. The median age was 39 years, for every 100 females, there were 101.8 males. For every 100 females age 18 and over, there were 100.9 males, the median income for a household in the city was $24,712, and for a family was $32,328. Males had an income of $25,804 versus $18,382 for females. The per capita income for the city was $14,636, about 15. 7% of families and 20. 6% of the population were below the poverty line, including 24. 6% of those under age 18 and 26. 9% of those age 65 or over. The area around Marfa is known as a center for contemporary artists
13.
Petroleum
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Petroleum is a naturally occurring, yellow-to-black liquid found in geological formations beneath the Earths surface, which is commonly refined into various types of fuels. Components of petroleum are separated using a technique called fractional distillation and it consists of hydrocarbons of various molecular weights and other organic compounds. The name petroleum covers both naturally occurring unprocessed crude oil and petroleum products that are made up of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms, usually zooplankton and algae, are buried underneath sedimentary rock, Petroleum has mostly been recovered by oil drilling. Drilling is carried out studies of structural geology, sedimentary basin analysis. Petroleum is used in manufacturing a variety of materials. Concern over the depletion of the earths finite reserves of oil, the burning of fossil fuels plays the major role in the current episode of global warming. The word petroleum comes from Greek, πέτρα for rocks and Greek, the term was found in 10th-century Old English sources. It was used in the treatise De Natura Fossilium, published in 1546 by the German mineralogist Georg Bauer, Petroleum, in one form or another, has been used since ancient times, and is now important across society, including in economy, politics and technology. Great quantities of it were found on the banks of the river Issus, ancient Persian tablets indicate the medicinal and lighting uses of petroleum in the upper levels of their society. By 347 AD, oil was produced from bamboo-drilled wells in China, early British explorers to Myanmar documented a flourishing oil extraction industry based in Yenangyaung that, in 1795, had hundreds of hand-dug wells under production. The mythological origins of the oil fields at Yenangyaung, and its hereditary monopoly control by 24 families, Pechelbronn is said to be the first European site where petroleum has been explored and used. The still active Erdpechquelle, a spring where petroleum appears mixed with water has been used since 1498, Oil sands have been mined since the 18th century. In Wietze in lower Saxony, natural asphalt/bitumen has been explored since the 18th century, both in Pechelbronn as in Wietze, the coal industry dominated the petroleum technologies. In 1848 Young set up a small business refining the crude oil, Young eventually succeeded, by distilling cannel coal at a low heat, in creating a fluid resembling petroleum, which when treated in the same way as the seep oil gave similar products. The production of oils and solid paraffin wax from coal formed the subject of his patent dated 17 October 1850. In 1850 Young & Meldrum and Edward William Binney entered into partnership under the title of E. W. Binney & Co. at Bathgate in West Lothian, the worlds first oil refinery was built in 1856 by Ignacy Łukasiewicz. The demand for petroleum as a fuel for lighting in North America, edwin Drakes 1859 well near Titusville, Pennsylvania, is popularly considered the first modern well
14.
Natural gas
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It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years. The energy that the plants originally obtained from the sun is stored in the form of bonds in the gas. Natural gas is a fuel used as a source of energy for heating, cooking. It is also used as fuel for vehicles and as a feedstock in the manufacture of plastics. Natural gas is found in underground rock formations or associated with other hydrocarbon reservoirs in coal beds. Petroleum is another resource and fossil fuel found in proximity to. Most natural gas was created over time by two mechanisms, biogenic and thermogenic, biogenic gas is created by methanogenic organisms in marshes, bogs, landfills, and shallow sediments. Deeper in the earth, at temperature and pressure, thermogenic gas is created from buried organic material. In petroleum production gas is burnt as flare gas. The World Bank estimates that over 150 cubic kilometers of gas are flared or vented annually. Before natural gas can be used as a fuel, most, Natural gas is often informally referred to simply as gas, especially when compared to other energy sources such as oil or coal. However, it is not to be confused with gasoline, especially in North America, Natural gas was used by the Chinese in about 500 BCE. They discovered a way to transport gas seeping from the ground in crude pipelines of bamboo to where it was used to salt water to extract the salt. The worlds first industrial extraction of gas started at Fredonia, New York. By 2009,66000 km³ had been used out of the total 850000 km³ of estimated remaining reserves of natural gas. An annual increase in usage of 2–3% could result in currently recoverable reserves lasting significantly less, unwanted natural gas was a disposal problem in the active oil fields. If there was not a market for natural gas near the wellhead it was expensive to pipe to the end user. In the 19th century and early 20th century, unwanted gas was burned off at oil fields
15.
Mid-Continent oil province
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The Mid-continent oil field is a broad area containing hundreds of oil fields in Arkansas, Kansas, Louisiana, New Mexico, Oklahoma and Texas. The area, which consists of geological strata and diverse trap types, was discovered and exploited during the first half of the 20th century. Most of the oil found in the onshore mid-continent oil field is considered to be of the mixed base or intermediate type. The first commercially successful oil well drilled in what was to be called the Mid-continent Oil Field was the Norman No.1 near Neodesha, Kansas and it became known as the Mid-continent Oil Field. Continued drilling found many other oil fields and pools within the Mid-continent, historically this area has produced more oil than any other area in the United States, and until the discovery of oil in the Middle East, was the largest known oil reserve in the world. The Texas Railroad Commission estimates that the Texas reserves alone were 190 billion barrels of oil including the more than 60 billion already produced. This led to depletion of the resources and the immediate fall of oil prices. Also, the influx of thousands of oil field workers led to wild growth of nearby boom towns. The states eventually succeeded in regulating the industry and passing laws for the distribution of oil royalties. Because of this early uncontrolled exploitation, much of the reserves in the Mid-continent have been depleted, Oil operators, in addition to continued exploration, use a variety of techniques to increase production, including deep wells, injection wells, etc. Arkansas,37 million barrels —Ranked 19th in the U. S. Louisiana,428 million barrels —Ranked 7th in the U. S. Kansas,263 million barrels —Ranked 12th in the U. S. New Mexico,705 million barrels —Ranked 5th in the U. S. Oklahoma,569 million barrels —Ranked 6th in the U. S. Texas,4,871 million barrels —Ranked 1st in the U. S. El Dorado,1915, Kansas, First oil field found using science/geologic mapping. Was 10% of the known reserves of oil at the time of discovery and produced 12. 8% of the nations oil in 1918. Corsicana,1896, Texas, plus 44 million barrels little reserve remaining Bartlesville,1897,1, Oklahoma,325 million barrels little reserve remaining Cushing,1912, Oklahoma Healdton,1913, Franklin No. 1, Oklahoma Greater Seminole,1926, Oklahoma, plus 200 million barrels McCamey,1928, Texas Oklahoma City, No.1 Discovery Well,1928, Oklahoma. 1, Wild Mary Sudik, gusher did not blow until March 25, 1930—she sprayed an estimated 3,000 barrels an hour for the next 11 days East Texas,1930,3, Texas Caddo Pine Island, Louisiana, Auffenhauser No. 1,1906 Smackover, Arkansas, No.1 J. T. Murphy,1922 El Dorado, Arkansas,1,1919 Rodessa, Caddo Parish, Louisiana, O. J
16.
Potassium
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Potassium is a chemical element with symbol K and atomic number 19. It was first isolated from potash, the ashes of plants, in the periodic table, potassium is one of the alkali metals. Potassium in nature only in ionic salts. It is found dissolved in sea water, and is part of many minerals, naturally occurring potassium is composed of three isotopes, of which 40K is radioactive. Traces of 40K are found in all potassium, and it is the most common radioisotope in the human body, Potassium is chemically very similar to sodium, the previous element in Group 1 of the periodic table. They have a similar energy, which allows for each atom to give up its sole outer electron. That they are different elements combine with the same anions to make similar salts was suspected in 1702. Most industrial applications of potassium exploit the high solubility in water of potassium compounds, heavy crop production rapidly depletes the soil of potassium, and this can be remedied with agricultural fertilizers containing potassium, accounting for 95% of global potassium chemical production. Potassium ions are necessary for the function of all living cells, fresh fruits and vegetables are good dietary sources of potassium. Potassium is the second least dense metal after lithium and it is a soft solid with a low melting point, and can be easily cut with a knife. Freshly cut potassium is silvery in appearance, but it begins to tarnish toward gray immediately on exposure to air, in a flame test, potassium and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers. Neutral potassium atoms have 19 electrons, one more than the stable configuration of the noble gas argon. This process requires so little energy that potassium is readily oxidized by atmospheric oxygen, in contrast, the second ionization energy is very high, because removal of two electrons breaks the stable noble gas electronic configuration. Potassium therefore does not readily form compounds with the state of +2 or higher. Potassium is an active metal that reacts violently with oxygen in water. With oxygen it forms potassium peroxide, and with water potassium forms potassium hydroxide, the reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas. Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium and this reaction requires only traces of water, because of this, potassium and the liquid sodium-potassium — NaK — are potent desiccants that can be used to dry solvents prior to distillation. Because of the sensitivity of potassium to water and air, reactions with other elements are only in an inert atmosphere such as argon gas using air-free techniques
17.
Sylvite
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Sylvite, or sylvine, is potassium chloride in natural mineral form. It forms crystals in the system very similar to normal rock salt. The two are, in fact, isomorphous, Sylvite is colorless to white with shades of yellow and red due to inclusions. It has a Mohs hardness of 2.5 and a gravity of 1.99. It has a index of 1.4903. Sylvite has a salty taste with a distinct bitterness, Sylvite is one of the last evaporite minerals to precipitate out of solution. As such, it is found in very dry saline areas. Its principal use is as a potassium fertilizer, Sylvite is found in many evaporite deposits worldwide. Massive bedded deposits occur in New Mexico and western Texas, and in Utah in the US, the vast deposits in Saskatchewan, Canada were formed by the evaporation of a Devonian seaway. Sylvite is the mineral of Saskatchewan. Sylvite was first described in 1832 at Mt. Vesuvius near Napoli in Italy and named for the Dutch chemist, Sylvite, along with quartz, fluorite and halite, is used for spectroscopic prisms and lenses. Sylvinite Mineral Resources of Saskatchewan Chisholm, Hugh, ed. Sylvite
18.
Room and pillar mining
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Room and pillar, also called pillar and stall, is a mining system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars. The ore is extracted in two phases, the technique is usually used for relatively flat-lying deposits, such as those that follow a particular stratum. The room and pillar system is used in mining coal, iron and base metals ores, particularly found as manto or blanket deposits, stone and aggregates, talc. The key to successful room and pillar mining is in the selection of the pillar size. In general practice, the size of both room and pillars are kept almost equal, while in Bord & Pillar, pillar size is larger than bord. If the pillars are too small the mine collapse, but if they are too large then significant quantities of valuable material will be left behind. Room and pillar mining is one of the oldest mining methods, early room and pillar mines were developed more or less at random, with pillar sizes determined empirically and headings driven in whichever direction was convenient. Random mine layout makes ventilation planning difficult, and if the pillars are too small, in coal mines, pillar failures are known as squeezes because the roof squeezes down, crushing the pillars. Once one pillar fails, the weight on the adjacent pillars increases, once started, such chain reactions can be extremely difficult to stop, even if they spread slowly. Room and pillar mines are developed on a grid basis except where geological features such as faults require the regular pattern to be modified, the size of the pillars is determined by calculation. The load-bearing capacity of the material above and below the material being mined, if one pillar fails and surrounding pillars are unable to support the area previously supported by the failed pillar they may in turn fail. This could lead to the collapse of the whole mine, to prevent this the mine is divided up into areas or panels. Pillars known as barrier pillars separate the panels, retreat mining is often the final stage of room and pillar mining. Once a deposit has been exhausted using this method, the pillars that were left behind initially are removed, or pulled, after the pillars are removed, the roof is allowed to collapse behind the mining area. Pillar removal must occur in a precise order to reduce the risks to workers. Longwall mining Notes Bibliography Hustrulid, William A. Bullock, Richard L, underground Mining Methods, Engineering Fundamentals and International Case Studies
19.
Halite
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Halite, commonly known as rock salt, is a type of salt, the mineral form of sodium chloride. The mineral is colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on the amount. It commonly occurs with other evaporite minerals such as several of the sulfates, halides. Halite occurs in vast beds of sedimentary evaporite minerals that result from the drying up of enclosed lakes, playas, salt beds may be hundreds of meters thick and underlie broad areas. In the United States and Canada extensive underground beds extend from the Appalachian basin of western New York through parts of Ontario, other deposits are in Ohio, Kansas, New Mexico, Nova Scotia and Saskatchewan. The Khewra salt mine is a deposit of halite near Islamabad. In the United Kingdom there are three mines, the largest of these is at Winsford in Cheshire producing on average a million tonnes per year. Salt domes are vertical diapirs or pipe-like masses of salt that have been squeezed up from underlying salt beds by mobilization due to the weight of overlying rock. Salt domes contain anhydrite, gypsum, and native sulfur, in addition to halite and sylvite and they are common along the Gulf coasts of Texas and Louisiana and are often associated with petroleum deposits. Germany, Spain, the Netherlands, Romania and Iran also have salt domes, salt glaciers exist in arid Iran where the salt has broken through the surface at high elevation and flows downhill. In all of these cases, halite is said to be behaving in the manner of a rheid, unusual, purple, fibrous vein filling halite is found in France and a few other localities. Halite crystals termed hopper crystals appear to be skeletons of the cubes, with the edges present and stairstep depressions on, or rather in. In a rapidly crystallizing environment, the edges of the cubes simply grow faster than the centers, halite crystals form very quickly in some rapidly evaporating lakes resulting in modern artifacts with a coating or encrustation of halite crystals. Halite flowers are rare stalactites of curling fibers of halite that are found in certain arid caves of Australias Nullarbor Plain, halite stalactites and encrustations are also reported in the Quincy native copper mine of Hancock, Michigan. Halite is often used both residentially and municipally for managing ice, because brine has a lower freezing point than pure water, putting salt or saltwater on ice that is near 0 °C will cause it to melt. It is common for homeowners in cold climates to spread salt on their sidewalks and driveways after a snow storm to melt the ice. It is not necessary to use so much salt that the ice is melted, rather. Also, many cities will spread a mixture of sand and salt on roads during, in addition to de-icing, rock salt is occasionally used in agriculture
20.
Ouachita Mountains
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The Ouachita Mountains are a mountain range in west central Arkansas and southeastern Oklahoma. The ranges subterranean roots may extend as far as central Texas, along with the Ozark Mountains, the Ouachita Mountains form the U. S. Interior Highlands, one of the few mountainous regions between the Rocky Mountains and the Appalachian Mountains. The highest peak in the Ouachitas is Mount Magazine in west-central Arkansas which rises to 2,753 feet, R. Harlan claimed that the word Ouachita is composed of two Choctaw words, ouac, a buffalo, and chito, large. It means the country of large buffaloes, numerous herds of the American bison having formerly covered the prairies of Ouachita, historian Muriel H. Wright wrote that the name was probably derived from the Choctaw words owa, meaning hunt and chito, meaning big. She said that meant a big hunt. The Ouachita Mountains are a section of the larger Ouachita province. The Ouachita Mountains are fold mountains like the Appalachian Mountains to the east, during the Pennsylvanian period, roughly 300 million years ago, the coastline of the Gulf of Mexico ran through the central parts of Arkansas. The South American Plate drifted northward, riding up over the denser North American continental crust, geologists call this collision the Ouachita orogeny. The collision buckled the overriding plate, producing the fold mountains we call the Ouachitas, at one time the Ouachita Mountains were very similar in height to the current elevations of the Rocky Mountains. Because of the Ouachitas age, the tops have eroded away. Unlike most other ranges in the United States, the Ouachitas run east and west rather than north and south. Also, the Ouachitas are distinctive in that volcanism, metamorphism, the Ouachitas tend to be clustered into distinct sub-ranges separated by relatively broad valleys. The Ouachitas are noted for quartz crystal deposits around the Mount Ida area and this quartz was formed during the Ouachita orogeny, as folded rocks cracked and allowed fluids from deep in the Earth to fill the cracks. The Atoka Formation, formed in the Pennsylvanian Period, is a sequence of marine, mostly tan to gray silty sandstones, some rare calcareous beds and siliceous shales are known. The Collier sequence is composed of gray to black, lustrous shale containing occasional thin beds of dense, black, an interval of bluish-gray, dense to spary, thin-bedded limestone may be present. Near its top, the limestone is conglomeratic and pelletoidal, in part, with pebbles and cobbles of limestone, chert, meta-arkose and it was formed during the Late Cambrian. Tree species native to the Ouachita area include red, post, black, and white oak, shortleaf and loblolly pine
21.
Siltstone
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Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones. Siltstone is a sedimentary rock. As its name implies, it is composed of silt sized particles. Siltstones differ significantly from sandstones due to their smaller pores and higher propensity for containing a significant clay fraction, although often mistaken as a shale, siltstone lacks the fissility and laminations which are typical of shale. Unless the siltstone is fairly shaly, stratification is likely to be obscure, mudstone or shale are rocks that contain mud, which is material that has a range of silt and clay. Siltstone is differentiated by having a majority silt, not clay, folk, R. L.1965, Petrology of sedimentary rocks PDF version. 2nd ed.1981, ISBN 0-914696-14-9 Williams, Howel, Francis J. Turner and Charles M. Gilbert,1954, Petrography, W. H. Freeman
22.
Sandstone
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Sandstone is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains. Most sandstone is composed of quartz or feldspar because these are the most common minerals in the Earths crust, like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, quartz-bearing sandstone is converted into quartzite through heating and pressure, usually related to tectonic compression within orogenic belts. They are formed from cemented grains that may either be fragments of a rock or be mono-minerallic crystals. The cements binding these grains together are typically calcite, clays, grain sizes in sands are defined within the range of 0.0625 mm to 2 mm. The formation of sandstone involves two principal stages, first, a layer or layers of sand accumulates as the result of sedimentation, either from water or from air. Typically, sedimentation occurs by the settling out from suspension. The most common cementing materials are silica and calcium carbonate, which are derived either from dissolution or from alteration of the sand after it was buried. Colours will usually be tan or yellow, a predominant additional colourant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue. Red sandstones are seen in the Southwest and West of Britain, as well as central Europe. The regularity of the latter favours use as a source for masonry, either as a building material or as a facing stone. These physical properties allow the grains to survive multiple recycling events. Quartz grains evolve from rock, which are felsic in origin. Feldspathic framework grains are commonly the second most abundant mineral in sandstones, Feldspar can be divided into two smaller subdivisions, alkali feldspars and plagioclase feldspars. The different types of feldspar can be distinguished under a petrographic microscope, below is a description of the different types of feldspar. Alkali feldspar is a group of minerals in which the composition of the mineral can range from KAlSi3O8 to NaAlSi3O8. Plagioclase feldspar is a group of solid solution minerals that range in composition from NaAlSi3O8 to CaAl2Si2O8. Lithic framework grains are pieces of ancient source rock that have yet to weather away to individual mineral grains, accessory minerals are all other mineral grains in a sandstone, commonly these minerals make up just a small percentage of the grains in a sandstone
23.
Carbonate
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In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, a polyatomic ion with the formula of CO2−3. The name may mean an ester of carbonic acid, an organic compound containing the carbonate group C2. In geology and mineralogy, the term carbonate can refer both to carbonate minerals and carbonate rock, and both are dominated by the ion, CO2−3. Carbonate minerals are extremely varied and ubiquitous in chemically precipitated sedimentary rock, sodium carbonate and potassium carbonate have been used since antiquity for cleaning and preservation, as well as for the manufacture of glass. Carbonates are widely used in industry, e. g. in iron smelting, as a raw material for Portland cement and lime manufacture, in the composition of ceramic glazes, the carbonate ion is the simplest oxocarbon anion. It consists of one carbon atom surrounded by three oxygen atoms, in a planar arrangement, with D3h molecular symmetry. It has a mass of 60.01 g/mol and carries a total formal charge of −2. It is the base of the hydrogen carbonate ion, HCO−3. The Lewis structure of the ion has two single bonds to negative oxygen atoms, and one short double bond to a neutral oxygen. This structure is incompatible with the symmetry of the ion. This process is called calcination, after calx, the Latin name of quicklime or calcium oxide, CaO, exceptions include lithium, sodium, potassium and ammonium carbonates, as well as many uranium carbonates. In aqueous solution, carbonate, bicarbonate, carbon dioxide, in strongly basic conditions, the carbonate ion predominates, while in weakly basic conditions, the bicarbonate ion is prevalent. In more acid conditions, aqueous carbon dioxide, CO2, is the main form, thus sodium carbonate is basic, sodium bicarbonate is weakly basic, while carbon dioxide itself is a weak acid. Carbonated water is formed by dissolving CO2 in water under pressure, in living systems an enzyme, carbonic anhydrase, speeds the interconversion of CO2 and carbonic acid. Although the carbonate salts of most metals are insoluble in water, in solution this equilibrium between carbonate, bicarbonate, carbon dioxide and carbonic acid changes consonant to changing temperature and pressure conditions. In the case of ions with insoluble carbonates, e. g. CaCO3. This is an explanation for the buildup of scale inside pipes caused by hard water, in organic chemistry a carbonate can also refer to a functional group within a larger molecule that contains a carbon atom bound to three oxygen atoms, one of which is double bonded. These compounds are known as organocarbonates or carbonate esters, and have the general formula ROCOOR′
24.
River delta
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A river delta is a landform that forms from deposition of sediment carried by a river as the flow leaves its mouth and enters slower-moving or standing water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, River deltas are ecologically important as they provide coastline defense, are home to many species, and can impact drinking water supply. The tidal currents also cannot be too strong, as sediment would wash out into the body faster than the river deposits it. Of course, the river must carry enough sediment to layer into deltas over time, the rivers velocity decreases rapidly, causing it to deposit the majority, if not all, of its load. This alluvium builds up to form the river delta, when the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, as a result, sediment drops out of the flow and deposits. Over time, this single channel builds a deltaic lobe, pushing its mouth into the standing water, as the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation. As the slope of the channel decreases, it becomes unstable for two reasons. First, gravity makes the flow in the most direct course down slope. If the river breaches its natural levees, it out onto a new course with a shorter route to the ocean. Second, as its slope gets lower, the amount of stress on the bed decreases, which results in deposition of sediment within the channel. This makes it easier for the river to breach its levees, often when the channel does this, some of its flow remains in the abandoned channel. When these channel-switching events occur, a mature delta develops a distributary network, another way these distributary networks form is from deposition of mouth bars. When this mid-channel bar is deposited at the mouth of a river and this results in additional deposition on the upstream end of the mouth-bar, which splits the river into two distributary channels. A good example of the result of this process is the Wax Lake Delta, in both of these cases, depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition. This results in the smoothing of the shape of the delta as the channels move across its surface. Because the sediment is laid down in fashion, the shape of these deltas approximates a fan. The more often the flow changes course, the shape develops as closer to an ideal fan, the Mississippi and Ural River deltas, with their birds-feet, are examples of rivers that do not avulse often enough to form a symmetrical fan shape
25.
Reef
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A reef is a bar of rock, sand, coral or similar material, lying beneath the surface of water. Reefs may be up to 261 feet below the surface, artificial reefs such as shipwrecks are sometimes created to enhance physical complexity on generally featureless sand bottoms in order to attract a diverse assemblage of organisms, especially fish. There is a variety of reef types, including oyster reefs. These biotic reef types take on additional names depending upon how the reef lies in relation to the land, Reef types include fringing reef, barrier reefs, as well as atolls. A fringing reef is a reef that is attached to an island, a barrier reef forms a calcareous barrier around an island resulting in a lagoon between the shore and the reef. An atoll is a reef with no land present. The reef front is a high energy locale whereas the internal lagoon will be at an energy with fine grained sediments. One useful definition distinguishes reefs from mounds as follows, reefs are held up by a macroscopic skeletal framework. Coral reefs are an excellent example of this kind, corals and calcareous algae grow on top of one another and form a three-dimensional framework that is modified in various ways by other organisms and inorganic processes. By contrast, mounds lack a macroscopic skeletal framework, mounds are built by microorganisms or by organisms that dont grow a skeletal framework. A microbial mound might be built exclusively or primarily by cyanobacteria, excellent examples of biostromes formed by cyanobacteria occur in the Great Salt Lake of Utah, and in Shark Bay, Western Australia. Cyanobacteria do not have skeletons and individuals are microscopic, cyanobacteria encourage the precipitation or accumulation of calcium carbonate and can produce distinct sediment bodies in composition that have relief on the seafloor. Cyanobacterial mounds were most abundant before the evolution of shelly macroscopic organisms, bryozoans and crinoids, common contributors to marine sediments during the Mississippian, produced a very different kind of mound. Bryozoans are small and the skeletons of crinoids disintegrate, however, bryozoan and crinoid meadows can persist over time and produce compositionally distinct bodies of sediment with depositional relief. The Proterozoic Belt Supergroup contains evidence of microbial mat and dome structures similar to stromatolite reef complexes. Ancient reefs buried within stratigraphic sections are of considerable interest to geologists because they provide information about the location in Earths history. Corals, including some major extinct groups Rugosa and Tabulata, have been important reef builders through much of the Phanerozoic since the Ordovician Period. However, other groups, such as calcifying algae, especially members of the red algae Rhodophyta
26.
Evaporite
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Evaporite is a name for a water-soluble mineral sediment that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of deposits, marine, which can also be described as ocean deposits, and non-marine. Evaporites are considered sedimentary rocks and are formed by chemical sediments, although all water bodies on the surface and in aquifers contain dissolved salts, the water must evaporate into the atmosphere for the minerals to precipitate. For this to happen, the body must enter a restricted environment where water input into this environment remains below the net rate of evaporation. This is usually an arid environment with a basin fed by a limited input of water. When evaporation occurs, the water is enriched in salts. Marine evaporites tend to have thicker deposits and are usually the focus of extensive research. They also have a system of evaporation, when scientists evaporate ocean water in a laboratory, the minerals are deposited in a defined order that was first demonstrated by Usiglio in 1884. The first phase of the experiment begins when about 50% of the water depth remains. At this point, minor carbonates begin to form, the next phase in the sequence comes when the experiment is left with about 20% of its original level. At this point, the mineral gypsum begins to form, which is followed by halite at 10%. Kieserite may also be included, which often make up less than four percent of the overall content. However, there are approximately 80 different minerals that have been reported found in evaporite deposits, common minerals that are found in these deposits include blödite, borax, epsomite, gaylussite, glauberite, mirabilite, thenardite and trona. Non-marine deposits may also contain halite, gypsum, and anhydrite and this, however, does not make non-marine deposits any less important, these deposits often help to paint a picture into past Earth climates. Some particular deposits even show important tectonic and climatic changes and these deposits also may contain important minerals that help in todays economy. Thick non-marine deposits that tend to form where evaporation rates will exceed the inflow rate. The inflow also has to occur in a basin, or one with restricted outflow, so that the sediment has time to pool. Primary examples of this are called saline lake deposits, examples of modern non-marine depositional environments include the Great Salt Lake in Utah and the Dead Sea, which lies between Jordan and Israel
27.
Syncline
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In structural geology, a syncline is a fold with younger layers closer to the center of the structure. A synclinorium is a syncline with superimposed smaller folds. Synclines are typically a downward fold, termed a synformal syncline, if the fold pattern is circular or elongate circular the structure is a basin. Folds typically form during crustal deformation as the result of compression that accompanies orogenic mountain building, sideling Hill roadcut along Interstate 68 in western Maryland, USA, where the Rockwell Formation and overlying Purslane Sandstone are exposed
28.
Panthalassa
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Panthalassa, also known as the Panthalassic or Panthalassan Ocean, was the superocean that surrounded the supercontinent Pangaea. During the Paleozoic—Mesozoic transition c.250 Ma it occupied almost 70% of Earths surface and its ocean-floor has completely disappeared because of the continuous subduction along the continental margins on its circumference. Panthalassa is also referred to as the Paleo-Pacific or Proto-Pacific because the Pacific Ocean developed from its centre in the Mesozoic to the present, the supercontinent Rodinia began to break-up 870–845 Ma probably as a consequence of a superplume caused by mantle slab avalanches along the margins of the supercontinent. In the Late Jurassic the Pacific Plate opened originating from a junction between the Panthalassic Farallon, Phoenix, and Izanagi plates. Panthalassa can be reconstructed based on magnetic lineations and fracture zones preserved in the western Pacific, in western Laurentia, a tectonic episode that preceded this rifting produced failed rifts that harboured large depositional basins in Western Laurentia. The global ocean of Mirovia, an ocean that surrounded Rodinia, started to shrink as the Pan-African ocean, between 650 million and 550 million years ago, another supercontinent started to form, Pannotia, which was shaped like a V. Inside the V was Panthalassa, outside of the V were the Pan-African Ocean, furthermore, seismic tomography is being used to identify subducted slabs in the mantle, from which the location of former Panthalassic subduction zones can be derived. A series of such zones, called Telkhinia, defines two separate oceans or systems of oceanic plates — the Pontus and Thalassa oceans. Named marginal oceans or oceanic plates include Mongol-Okhotsk, Oimyakon, Slide Mountain Ocean, the western margin of Laurentia originated during the Neoproterozoic break-up of Rodinia. The North American Cordillera is an accretionary orogen which grew by the addition of allochthonous terranes along this margin from the Late Palaeozoic. Devonian back-arc volcanism reveals how this eastern Panthalassic margin developed into the margin it still is in the mid-Palaeozoic. Most of the fragments, volcanic arcs, and ocean basins added to Laurentia this way contained faunas of Tethyan or Asian affinity. Similar terranes added to the northern Laurentia, in contrast, have affinities with Baltica, Siberia, and these latter terranes were probably accreted along the eastern Panthalassa margin by a Caribbean–Scotia-style subduction system. Today the region is dominated by the collision of the Australian Plate with a network of plate boundaries in south-east Asia. Spreading along the Pacific-Phoenix ridge ended 83 Ma at the Osbourn Trough at the Tonga-Kermadec Trench, during the Permian atolls developed near the Equator on the mid-Panthalassic seamounts. One such migrating atoll complex now form a 2-kilometre-long and 100-to-150-metre-wide body of limestone in central Kyushu, south-west Japan. The Permian–Triassic extinction event c.260 Ma, however, put an end to development with only dwarf taxa persisting throughout the Permian until the final fusuline extinction c.252 Ma. Permian fusulines also developed a remarkable provincialism by which fusulines can be grouped into six domains, because of the large size of Panthalassa a hundred million years could separate the accretion of different groups of fusulines
29.
Limestone
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Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate, about 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, most cave systems are through limestone bedrock. The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778, like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids, intraclasts and these organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragment, some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i. e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters and this produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance, the primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters. Limestones may also form in lacustrine and evaporite depositional environments, calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits a characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors, especially with weathered surfaces, Limestone may be crystalline, clastic, granular, or massive, depending on the method of formation. Crystals of calcite, quartz, dolomite or barite may line small cavities in the rock, when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams, particularly there are waterfalls. Calcium carbonate is deposited where evaporation of the leaves a solution supersaturated with the chemical constituents of calcite. Tufa, a porous or cellular variety of travertine, is found near waterfalls, coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the building process, limestone recrystallizes into marble
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Pennsylvanian (geology)
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The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly 323.2 million years ago to 298.9 million years ago Ma. As with most other units, the rock beds that define the Pennsylvanian are well identified. The Pennsylvanian is named after the U. S. state of Pennsylvania, the division between Pennsylvanian and Mississippian comes from North American stratigraphy. In Europe, the Mississippian and Pennsylvanian are one continuous sequence of lowland continental deposits and are grouped together as the Carboniferous Period. The current internationally used geologic timescale of the ICS gives the Mississippian and Pennsylvanian the rank of subperiods, all modern classes of fungi have been found in rocks of Pennsylvanian age. Amphibians were diverse and common, some were several meters long as adults, the collapse of the rainforest ecology in the mid Pennsylvanian removed many amphibian species that did not survive as well in the cooler, drier conditions. Reptiles, however, prospered due to specific key adaptations, one of the greatest evolutionary innovations of the Carboniferous was the amniote egg, which allowed for the further exploitation of the land by certain tetrapods. These included the earliest sauropsid reptiles, and the earliest known synapsid, small lizard-like animals quickly gave rise to many descendants. Reptiles underwent an evolutionary radiation, in response to the drier climate that followed the rainforest collapse. The Pennsylvanian has been variously subdivided, the Missourian or Monongahela corresponds to the rest of the Kasimovian. The Desmoinesian or Allegheny corresponds to the half of the Moscovian. The Atokan or upper Pottsville corresponds to the half of the Moscovian. The Morrowan corresponds to the Bashkirian, in the European subdivision, the Carboniferous is divided into two epochs, Dinantian and Silesian. The Silesian starts earlier than the Pennsylvanian and is divided in three ages, Namurian Westphalian Stephanian, the Late Carboniferous a Time of Great Coal Swamps, Paleomap project. World map from this time period, the Carboniferous -354 to 290 Million Years Ago, University of California Museum of Paleontology. Information on stratigraphies, localities, tectonics, and life, the Pennsylvanian Epoch of the Carboniferous Period,318 to 299 Mya, Paleos. com US Geological Survey comparison of time scales
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North America
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North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It can also be considered a subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16. 5% of the land area. North America is the third largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 565 million people in 23 independent states, or about 7. 5% of the worlds population, North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge. The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago, the Classic stage spans roughly the 6th to 13th centuries. The Pre-Columbian era ended with the migrations and the arrival of European settlers during the Age of Discovery. Present-day cultural and ethnic patterns reflect different kind of interactions between European colonists, indigenous peoples, African slaves and their descendants, European influences are strongest in the northern parts of the continent while indigenous and African influences are relatively stronger in the south. Because of the history of colonialism, most North Americans speak English, Spanish or French, the Americas are usually accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass previously unknown by Europeans. In 1507, Waldseemüller produced a map, in which he placed the word America on the continent of South America. He explained the rationale for the name in the accompanying book Cosmographiae Introductio, for Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespuccis name, but in its feminine form America, following the examples of Europa, Asia and Africa. Later, other mapmakers extended the name America to the continent, In 1538. Some argue that the convention is to use the surname for naming discoveries except in the case of royalty, a minutely explored belief that has been advanced is that America was named for a Spanish sailor bearing the ancient Visigothic name of Amairick. Another is that the name is rooted in a Native American language, the term North America maintains various definitions in accordance with location and context. In Canadian English, North America may be used to refer to the United States, alternatively, usage sometimes includes Greenland and Mexico, as well as offshore islands
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Gondwana
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In paleogeography, Gondwana, also Gondwanaland, is the name given to an ancient supercontinent. It is believed to have sutured about 600 to 530 million years ago, Gondwana formed prior to Pangaea, and later became part of it. Around 335 to 250 million years ago Gondwana and Laurasia joined together to form the supercontinent Pangaea, Gondwana then separated from Laurasia in the breakup of Pangaea, drifting farther south after the split. Gondwana itself then also broke apart, the continent of Gondwana was named by Austrian scientist Eduard Suess, after the Gondwana region of central northern India which is derived from Sanskrit for forest of the Gonds. The name had previously used in a geological context, first by H. B. From which the Gondwana sedimentary sequences are also described, for example, the plant family Proteaceae, known only from southern South America, South Africa, Australia, and New Zealand, is considered to have a Gondwanan distribution. This pattern is considered to indicate an archaic, or relict. The assembly of Gondwana was a protracted process, several orogenies led to its final amalgamation 550 to 500 million years ago at the end of the Ediacaran, and into the Cambrian. These include the Brasiliano Orogeny, the East African Orogeny, the Malagasy Orogeny, the final stages of Gondwanan assembly overlapped with the opening of the Iapetus Ocean between Laurentia and western Gondwana. During this interval, the Cambrian explosion occurred and this is the Famatinian block and it formerly continued the line of the Appalachians southwards. One of the sites of Gondwanan amalgamation was the East African Orogeny. The East African Orogeny at about 650–630 Mya affected a part of Arabia, north-eastern Africa, East Africa. Collins and Windley propose that in this orogeny, Azania collided with the Congo–Tanzania–Bangweulu Block, the later Malagasy orogeny at about 550–515 Mya affected Madagascar, eastern East Africa and southern India. In it, Neoproterozoic India collided with the already combined Azania and Congo–Tanzania–Bangweulu Block, at the same time, in the Kunga Orogeny Neoproterozoic India collided with the Australia/Mawson continent. Other large continental masses, including the core cratons of North America, Europe, when Pangaea broke up, two large masses, Gondwana and Laurasia, were formed. During the late Paleozoic, Gondwana extended from a point at or near the South Pole to near the Equator, across much of Gondwana, the climate was mild. During the Mesozoic, the world was on average warmer than it is today. Gondwana was then host to a variety of flora and fauna for many millions of years
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South America
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South America is a continent located in the western hemisphere, mostly in the southern hemisphere, with a relatively small portion in the northern hemisphere. It may also be considered a subcontinent of the Americas, which is the used in nations that speak Romance languages. The reference to South America instead of other regions has increased in the last decades due to changing geopolitical dynamics. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean, North America and it includes twelve sovereign states, a part of France, and a non-sovereign area. In addition to this, the ABC islands of the Kingdom of the Netherlands, Trinidad and Tobago, South America has an area of 17,840,000 square kilometers. Its population as of 2005 has been estimated at more than 371,090,000, South America ranks fourth in area and fifth in population. Brazil is by far the most populous South American country, with more than half of the population, followed by Colombia, Argentina, Venezuela. In recent decades Brazil has also concentrated half of the regions GDP and has become a first regional power, most of the population lives near the continents western or eastern coasts while the interior and the far south are sparsely populated. Most of the continent lies in the tropics, the continents cultural and ethnic outlook has its origin with the interaction of indigenous peoples with European conquerors and immigrants and, more locally, with African slaves. Given a long history of colonialism, the majority of South Americans speak Portuguese or Spanish. South America occupies the portion of the Americas. The continent is delimited on the northwest by the Darién watershed along the Colombia–Panama border. Almost all of mainland South America sits on the South American Plate, South Americas major mineral resources are gold, silver, copper, iron ore, tin, and petroleum. These resources found in South America have brought high income to its countries especially in times of war or of rapid growth by industrialized countries elsewhere. However, the concentration in producing one major export commodity often has hindered the development of diversified economies and this is leading to efforts to diversify production to drive away from staying as economies dedicated to one major export. South America is one of the most biodiverse continents on earth, South America is home to many interesting and unique species of animals including the llama, anaconda, piranha, jaguar, vicuña, and tapir. The Amazon rainforests possess high biodiversity, containing a proportion of the Earths species. Brazil is the largest country in South America, encompassing around half of the land area
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Africa
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Africa is the worlds second-largest and second-most-populous continent. At about 30.3 million km² including adjacent islands, it covers 6% of Earths total surface area and 20.4 % of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the human population. The continent includes Madagascar and various archipelagos and it contains 54 fully recognized sovereign states, nine territories and two de facto independent states with limited or no recognition. Africas population is the youngest amongst all the continents, the age in 2012 was 19.7. Algeria is Africas largest country by area, and Nigeria by population, afarensis, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens found in Ethiopia being dated to circa 200,000 years ago. Africa straddles the equator and encompasses numerous climate areas, it is the continent to stretch from the northern temperate to southern temperate zones. Africa hosts a diversity of ethnicities, cultures and languages. In the late 19th century European countries colonized most of Africa, Africa also varies greatly with regard to environments, economics, historical ties and government systems. However, most present states in Africa originate from a process of decolonization in the 20th century, afri was a Latin name used to refer to the inhabitants of Africa, which in its widest sense referred to all lands south of the Mediterranean. This name seems to have referred to a native Libyan tribe. The name is connected with Hebrew or Phoenician ʿafar dust. The same word may be found in the name of the Banu Ifran from Algeria and Tripolitania, under Roman rule, Carthage became the capital of the province of Africa Proconsularis, which also included the coastal part of modern Libya. The Latin suffix -ica can sometimes be used to denote a land, the later Muslim kingdom of Ifriqiya, modern-day Tunisia, also preserved a form of the name. According to the Romans, Africa lay to the west of Egypt, while Asia was used to refer to Anatolia, as Europeans came to understand the real extent of the continent, the idea of Africa expanded with their knowledge. 25,4, whose descendants, he claimed, had invaded Libya, isidore of Seville in Etymologiae XIV.5.2. Suggests Africa comes from the Latin aprica, meaning sunny, massey, in 1881, stated that Africa is derived from the Egyptian af-rui-ka, meaning to turn toward the opening of the Ka. The Ka is the double of every person and the opening of the Ka refers to a womb or birthplace
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Precambrian
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The Precambrian is the earliest period of Earths history, set before the current Phanerozoic Eon. The Precambrian is a supereon that is subdivided into three eons of the time scale. It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, the Precambrian accounts for 89% of geologic time. Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earths history, the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from that time are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion. A stable crust was apparently in place by 4,412 Ma, the term Precambrian is recognized by the International Commission on Stratigraphy as a general term including the Archean and Proterozoic eons. It is still used by geologists and paleontologists for general discussions not requiring the more specific eon names and it was briefly called the Cryptozoic eon. A specific date for the origin of life has not been determined, carbon found in 3.8 billion year old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have found in Western Australia. Probable fossils 100 million years older have been found in the same area, there is a fairly solid record of bacterial life throughout the remainder of the Precambrian. The oldest fossil evidence from that era of such complex life comes from the Lantian formation of the Ediacarian period, a very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota, hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic era. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale. The explosion in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life, while land seems to have been devoid of plants and animals, cyanobacteria and other microbes formed prokaryotic mats that covered terrestrial areas. Evidence of the details of plate motions and other activity in the Precambrian has been poorly preserved. It is generally believed that small proto-continents existed prior to 4280 Ma, the supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch, one of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a Snowball Earth. The atmosphere of the early Earth is not well understood, most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and was lacking in free oxygen
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Supercontinent
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In geology, a supercontinent is the assembly of most or all of Earths continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous, Many earth scientists, such as P. F. Hoffman, use the term supercontinent to mean a clustering of all continents. This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times, the landmass of Pangaea is the collective name describing all of these continental masses when they were most recently in proximity to one another. This would classify Pangaea as a supercontinent, according to the definition by Rogers and Santosh, a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past, the positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are less certain. The following table displays historical supercontinents, using a general definition, there are two contrasting models for supercontinent evolution through geological time. The first model theorizes that at least two separate supercontinents existed comprising Vaalbara and Kenorland, the Neoarchean supercontinent consisted of Superia and Sclavia. These parts of Neoarchean age broke off at ~2300 and 2090 Ma, Nuna continued to develop during the Mesoproterozoic, primarily by lateral accretion of juvenile arcs, and in ~1000 Ma Nuna collided with other land masses, forming Rodinia. Between ~800 and 700 Ma Rodinia broke apart, however, before completely breaking up, some fragments of Rodinia had already come together to form Gondwana by ~530 Ma. Pangaea formed by ~300 Ma through the collision of Gondwana, Laurentia, Baltica, during the intervening periods, the poles conform to a unified apparent polar wander path. The explanation for the duration of the Protopangea-Paleopangea supercontinent appears to be that Lid Tectonics prevailed during Precambrian times. Plate Tectonics as seen on the contemporary Earth became dominant only during the part of geological times. The Phanerozoic supercontinent Pangaea began to break up 180 Ma and is doing so today. Because Pangaea is the most recent of Earths supercontinents, it is the most well known, contributing to Pangaeas popularity in the classroom is the fact that its reconstruction is almost as simple as fitting the present continents bordering the Atlantic-type oceans like puzzle pieces. A supercontinent cycle is the break-up of one supercontinent and the development of another, supercontinent cycles are not the same as the Wilson cycle, which is the opening and closing of an individual oceanic basin. The Wilson cycle rarely synchronizes with the timing of a supercontinent cycle, however, supercontinent cycles and Wilson cycles were both involved in the creation of Pangaea and Rodinia
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Passive margin
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A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere, Continental rifting creates new ocean basins. Eventually the continental rift forms a ridge and the locus of extension moves away from the continent-ocean boundary. The transition between the continental and oceanic lithosphere that was created by rifting is known as a passive margin. Passive margins are found at every ocean and continent boundary that is not marked by a fault or a subduction zone. Passive margins define the region around the Atlantic Ocean, Arctic Ocean, and western Indian Ocean and they are also found on the east coast of North America and South America, in western Europe and most of Antarctica. East Asia also contains some passive margins and this refers to whether a crustal boundary between oceanic lithosphere and continental lithosphere is a plate boundary or not. Active margins are found on the edge of a continent where subduction occurs and these are often marked by uplift and volcanic mountain belts on the continental plate. Less often there is a fault, as defines the southern coastline of W. Africa. Most of the eastern Indian Ocean and nearly all of the Pacific Ocean margin are examples of active margins, while a weld between oceanic and continental lithosphere is called a passive margin, it is not an inactive margin. Active subsidence, sedimentation, growth faulting, pore formation and migration are all active processes on passive margins. Passive margins are only passive in that they are not active plate boundaries, Passive margins consist of both onshore coastal plain and offshore continental shelf-slope-rise triads. Coastal plains are dominated by fluvial processes, while the continental shelf is dominated by deltaic. The great rivers drain across passive margins, extensive estuaries are common on mature passive margins. Although there are kinds of passive margins, the morphologies of most passive margins are remarkably similar. Typically they consist of a shelf, continental slope, continental rise. The morphological expression of features are largely defined by the underlying transitional crust. Passive margins defined by a fluvial sediment budget and those dominated by coral
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Variscan orogeny
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The Variscan or Hercynian orogeny is a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica and Gondwana to form the supercontinent of Pangaea. Hercynian, on the hand, derives from the Hercynian Forest. Both words were descriptive terms of strike directions observed by geologists in the field, variscan for southwest to northeast, the variscan direction reflected the direction of ancient fold belts cropping out throughout Germany and adjacent countries and the meaning shifted from direction to the fold belt proper. One of the pioneers in research on the Variscan fold belt was the German geologist Franz Kossmat, the other direction, Hercynian, for the direction of the Harz Mountains in Germany, saw a similar shift in meaning. Today Hercynian is often used as a synonym for Variscan, but is less used than the latter. In the USA it is used for European orogenies, the contemporaneous. The regional term Variscan underwent a further meaning shift since the 1960s, geologists generally began to use it to characterize late Paleozoic fold-belts and orogenic phases having an age of approximately 380 to 280 Ma. The North American and European Variscan Belt includes the mountains of Portugal and Spain, southwestern Ireland, Cornwall, Devon, Pembrokeshire, the Gower Peninsula and the Vale of Glamorgan. Its effects are present in France from Brittany, below the Paris Basin to the Ardennes, the Massif Central, the Variscan Belt reappears in Sardinia in Italy and in Germany where the Rhine Massif, the Black Forest and Harz Mountains remain as testimony. In the Czech Republic and Eastern Poland the Bohemian Massif is the end of the unmodified Variscan belt of crustal deformation in Europe. Further Variscan developments to the southeast are partly hidden and overprinted by the alpine orogeny, in the Alps a Variscan core is built by Mercantour, Pelvoux, Belledonne, Montblanc and Aar Massif. Dinaric, Greek and Turkish mountain chains are the termination of the Variscan proper. The Variscan was contemporaneous with the Acadian and Alleghenian orogeny in the United States and Canada, responsible for forming the Ouachita, North American areas with Variscan foldbelts include New England, Nova Scotia and Newfoundland and Labrador. Variscan mountains in a chronological sense include the Urals, the Pamir. The Variscan orogeny involved a complicated assembly of different microplates and heterochronous collisions. Plate convergence that caused the Caledonian orogeny in the Silurian continued to form the Variscan orogeny in the succeeding Devonian, both orogenies resulted in the assembly of a super-continent, Pangaea, which was essentially complete by the end of the Carboniferous. In the Ordovician Period, a mass, which has been named Gondwana. Off to the west were three other masses, Laurentia, Siberia and Baltica, located as if on the vertices of a triangle, to the south of them was a large archipelago, the terrane Avalonia, rifted off the north Gondwana margin in early Ordovician
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Foreland basin
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A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. The width and depth of the basin is determined by the flexural rigidity of the underlying lithosphere. The foreland basin receives sediment that is eroded off the adjacent mountain belt, foreland basins represent an endmember basin type, the other being rift basins. Space for sediments is provided by loading and downflexure to form foreland basins, in contrast to rift basins, the wedge-top sits on top of the moving thrust sheets and contains all the sediments charging from the active tectonic thrust wedge. This is where piggyback basins form, the foredeep is the thickest sedimentary zone and thickens toward the orogen. Sediments are deposited via distal fluvial, lacustrine, deltaic, the forebulge and backbulge are the thinnest and most distal zones and are not always present. When present, they are defined by regional unconformities as well as aeolian, sedimentation is most rapid near the moving thrust sheet. Sediment transport within the foredeep is generally parallel to the strike of the thrust fault, the motion of the adjacent plates of the foreland basin can be determined by studying the active deformation zone with which it is connected. Today GPS measurements provide the rate at which one plate is moving relative to another and it is also important to consider that present day kinematics are unlikely to be the same as when deformation began. Thus, it is crucial to consider models to determine the long-term evolution of continental collisions. Comparing both modern GPS and non-GPS models allows deformation rates to be calculated, comparing these numbers to the geologic regime helps constrain the number of probable models as well as which model is more geologically accurate within a specific region. Seismicity determines where active zones of activity occur as well as measure the total fault displacements. Foreland basins form because as the mountain belt grows, it exerts a significant mass on the Earth’s crust and this occurs so that the weight of the mountain belt can be compensated by isostasy at the upflex of the forebulge. The plate tectonic evolution of a foreland basin involves three general stages. First, the passive margin stage with orogenic loading of previously stretched continental margin during the stages of convergence. Second, the early convergence stage defined by water conditions. The temperature underneath the orogen is much higher and weakens the lithosphere, thus, the thrust belt is mobile and the foreland basin system becomes deformed over time. Syntectonic unconformities demonstrate simultaneous subsidence and tectonic activity, foreland basins are filled with sediments which erode from the adjacent mountain belt
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Mya (unit)
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A year is the orbital period of the Earth moving in its orbit around the Sun. Due to the Earths axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the globe, four seasons are recognized, spring, summer, autumn. In tropical and subtropical regions several geographical sectors do not present defined seasons, but in the seasonal tropics, a calendar year is an approximation of the number of days of the Earths orbital period as counted in a given calendar. The Gregorian, or modern, calendar, presents its calendar year to be either a common year of 365 days or a year of 366 days, as do the Julian calendars. For the Gregorian calendar the average length of the year across the complete leap cycle of 400 years is 365.2425 days. The ISO standard ISO 80000-3, Annex C, supports the symbol a to represent a year of either 365 or 366 days, in English, the abbreviations y and yr are commonly used. In astronomy, the Julian year is a unit of time, it is defined as 365.25 days of exactly 86400 seconds, totalling exactly 31557600 seconds in the Julian astronomical year. The word year is used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year. Similarly, year can mean the period of any planet, for example. The term can also be used in reference to any long period or cycle, west Saxon ġēar, Anglian ġēr continues Proto-Germanic *jǣran. Cognates are German Jahr, Old High German jār, Old Norse ár and Gothic jer, all the descendants of the Proto-Indo-European noun *yeh₁rom year, season. Cognates also descended from the same Proto-Indo-European noun are Avestan yārǝ year, Greek ὥρα year, season, period of time, Old Church Slavonic jarŭ, Latin annus is from a PIE noun *h₂et-no-, which also yielded Gothic aþn year. Both *yeh₁-ro- and *h₂et-no- are based on verbal roots expressing movement, *h₁ey- and *h₂et- respectively, the Greek word for year, ἔτος, is cognate with Latin vetus old, from the PIE word *wetos- year, also preserved in this meaning in Sanskrit vat-sa- yearling and vat-sa-ras year. Derived from Latin annus are a number of English words, such as annual, annuity, anniversary, etc. per annum means each year, anno Domini means in the year of the Lord. No astronomical year has an number of days or lunar months. Financial and scientific calculations often use a 365-day calendar to simplify daily rates, in the Julian calendar, the average length of a year is 365.25 days. In a non-leap year, there are 365 days, in a year there are 366 days
41.
Shale
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Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable, shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. Mudstones, on the hand, are similar in composition. Before the mid 19th century, the slate, shale. In the context of underground mining, shale was frequently referred to as slate well into the 20th century. Non-fissile rocks of similar composition but made of smaller than 0.06 mm are described as mudstones or claystone. Rocks with similar sizes but with less clay and therefore grittier are siltstones. Shale is the most common sedimentary rock, shales are typically composed of variable amounts of clay minerals and quartz grains and the typical color is gray. Addition of variable amounts of minor constituents alters the color of the rock, black shale results from the presence of greater than one percent carbonaceous material and indicates a reducing environment. Black shale can also be referred to as black metal, red, brown and green colors are indicative of ferric oxide, iron hydroxide, or micaceous minerals. Clays are the constituent of shales and other mudrocks. The clay minerals represented are largely kaolinite, montmorillonite and illite, clay minerals of Late Tertiary mudstones are expandable smectites whereas in older rocks especially in mid- to early Paleozoic shales illites predominate. The transformation of smectite to illite produces silica, sodium, calcium, magnesium, iron and these released elements form authigenic quartz, chert, calcite, dolomite, ankerite, hematite and albite, all trace to minor minerals found in shales and other mudrocks. Shales and mudrocks contain roughly 95 percent of the matter in all sedimentary rocks. However, this amounts to less than one percent by mass in an average shale, black shales, which form in anoxic conditions, contain reduced free carbon along with ferrous iron and sulfur. Pyrite and amorphous iron sulfide along with carbon produce the black coloration, the process in the rock cycle which forms shale is called compaction. The fine particles that compose shale can remain suspended in long after the larger particles of sand have deposited. Shales are typically deposited in very slow moving water and are found in lakes and lagoonal deposits, in river deltas, on floodplains
42.
Salt (chemistry)
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In chemistry, a salt is an ionic compound that results from the neutralization reaction of an acid and a base. Salts are composed of related numbers of cations and anions so that the product is electrically neutral and these component ions can be inorganic, such as chloride, or organic, such as acetate, and can be monatomic, such as fluoride, or polyatomic, such as sulfate. There are several varieties of salts, salts that hydrolyze to produce hydroxide ions when dissolved in water are alkali salts, whilst those that hydrolyze to produce hydronium ions in water are acidic salts. Neutral salts are those salts that are neither acidic nor basic, zwitterions contain an anionic centre and a cationic centre in the same molecule, but are not considered to be salts. Examples of zwitterions include amino acids, many metabolites, peptides, usually, non-dissolved salts at standard conditions for temperature and pressure are solid, but there are exceptions. Molten salts and solutions containing dissolved salts are called electrolytes, as they are able to conduct electricity. As observed in the cytoplasm of cells, in blood, urine, plant saps and mineral waters, therefore, their salt content is given for the respective ions. Salts can appear to be clear and transparent, opaque, and even metallic, in many cases, the apparent opacity or transparency are only related to the difference in size of the individual monocrystals. Since light reflects from the boundaries, larger crystals tend to be transparent. The color of the salt is due to the electronic structure in the d-orbitals of transition elements or in the conjugated organic dye framework. Different salts can elicit all five basic tastes, e. g. salty, sweet, sour, bitter, and umami or savory. Salts of strong acids and strong bases are non-volatile and odorless and that slow, partial decomposition is usually accelerated by the presence of water, since hydrolysis is the other half of the reversible reaction equation of formation of weak salts. Many ionic compounds can be dissolved in water or other similar solvents, the exact combination of ions involved makes each compound have a unique solubility in any solvent. The solubility is dependent on how well each ion interacts with the solvent, for example, all salts of sodium, potassium and ammonium are soluble in water, as are all nitrates and many sulfates – barium sulfate, calcium sulfate and lead sulfate are examples of exceptions. However, ions that bind tightly to each other and form highly stable lattices are less soluble, for example, most carbonate salts are not soluble in water, such as lead carbonate and barium carbonate. Some soluble carbonate salts are, sodium carbonate, potassium carbonate, solid salts do not conduct electricity. Moreover, solutions of salts also conduct electricity, the name of a salt starts with the name of the cation followed by the name of the anion. Salts are often referred to only by the name of the cation or by the name of the anion. g
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Gypsum
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Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer, and as the constituent in many forms of plaster, blackboard chalk. Mohs scale of hardness, based on scratch Hardness comparison. It forms as a mineral and as a hydration product of anhydrite. The word gypsum is derived from the Greek word γύψος, plaster, because the quarries of the Montmartre district of Paris have long furnished burnt gypsum used for various purposes, this dehydrated gypsum became known as plaster of Paris. Upon addition of water, after a few tens of minutes plaster of Paris becomes regular gypsum again, causing the material to harden or set in ways that are useful for casting, Gypsum was known in Old English as spærstān, spear stone, referring to its crystalline projections. Gypsum may act as a source of sulfur for plant growth, which was discovered by J. M. Mayer, american farmers were so anxious to acquire it that a lively smuggling trade with Nova Scotia evolved, resulting in the so-called Plaster War of 1820. In the 19th century, it was known as lime sulfate or sulfate of lime. Gypsum is moderately water-soluble and, in contrast to most other salts, it exhibits retrograde solubility, when gypsum is heated in air it loses water and converts first to calcium sulfate hemihydrate, and, if heated further, to anhydrous calcium sulfate. As for anhydrite, its solubility in saline solutions and in brines is also dependent on NaCl concentration. Gypsum crystals are found to contain water and hydrogen bonding. Gypsum occurs in nature as flattened and often twinned crystals, and transparent, selenite contains no significant selenium, rather, both substances were named for the ancient Greek word for the Moon. Selenite may also occur in a silky, fibrous form, in case it is commonly called satin spar. Finally, it may also be granular or quite compact, in hand-sized samples, it can be anywhere from transparent to opaque. A very fine-grained white or lightly tinted variety of gypsum, called alabaster, is prized for ornamental work of various sorts, in arid areas, gypsum can occur in a flower-like form, typically opaque, with embedded sand grains called desert rose. It also forms some of the largest crystals found in nature, up to 12 m long, Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks. Deposits are known to occur in strata from as far back as the Archaean eon, Gypsum is deposited from lake and sea water, as well as in hot springs, from volcanic vapors, and sulfate solutions in veins. Hydrothermal anhydrite in veins is commonly hydrated to gypsum by groundwater in near-surface exposures and it is often associated with the minerals halite and sulfur
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Hydrocarbon
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In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon, and thus are group 14 hydrides. Hydrocarbons from which one atom has been removed are functional groups. Aromatic hydrocarbons, alkanes, alkenes, cycloalkanes and alkyne-based compounds are different types of hydrocarbons, the classifications for hydrocarbons, defined by IUPAC nomenclature of organic chemistry are as follows, Saturated hydrocarbons are the simplest of the hydrocarbon species. They are composed entirely of single bonds and are saturated with hydrogen, the formula for acyclic saturated hydrocarbons is CnH2n+2. The most general form of saturated hydrocarbons is CnH2n+2, where r is the number of rings and those with exactly one ring are the cycloalkanes. Saturated hydrocarbons are the basis of petroleum fuels and are found as linear or branched species. Substitution reaction is their characteristics property, hydrocarbons with the same molecular formula but different structural formulae are called structural isomers. As given in the example of 3-methylhexane and its higher homologues, chiral saturated hydrocarbons constitute the side chains of biomolecules such as chlorophyll and tocopherol. Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms and those with double bond are called alkenes. Those with one double bond have the formula CnH2n and those containing triple bonds are called alkyne. Those with one triple bond have the formula CnH2n−2, aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring. Hydrocarbons can be gases, liquids, waxes or low melting solids or polymers, in terms of shells, carbon consists of an incomplete outer shell, which comprises 4 electrons, and thus has 4 electrons available for covalent or dative bonding. Some hydrocarbons also are abundant in the solar system, lakes of liquid methane and ethane have been found on Titan, Saturns largest moon, confirmed by the Cassini-Huygens Mission. Hydrocarbons are also abundant in nebulae forming polycyclic aromatic hydrocarbon compounds, hydrocarbons are a primary energy source for current civilizations. The predominant use of hydrocarbons is as a fuel source. In their solid form, hydrocarbons take the form of asphalt, mixtures of volatile hydrocarbons are now used in preference to the chlorofluorocarbons as a propellant for aerosol sprays, due to chlorofluorocarbons impact on the ozone layer. Methane and ethane are gaseous at ambient temperatures and cannot be liquefied by pressure alone. Propane is however easily liquefied, and exists in propane bottles mostly as a liquid, butane is so easily liquefied that it provides a safe, volatile fuel for small pocket lighters
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Facies
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Ideally, a sedimentary facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment. Sedimentary facies are either descriptive or interpretative, sedimentary facies are bodies of sediment that are recognizably distinct from adjacent sediments that resulted from different depositional environments. Generally, geologists distinguish facies by the aspect of the rock or sediment being studied, Facies based on petrological characters are called lithofacies, whereas facies based on fossil content are called biofacies. A facies is usually further subdivided, for example, one might refer to a tan, the characteristics of the rock unit come from the depositional environment and from the original composition. Sedimentary facies reflect their depositional environment, each facies being a kind of sediment for that area or environment. Since its inception, the concept has been extended to related geological concepts. For example, characteristic associations of organic microfossils, and particulate organic material, discrete seismic units are similarly referred to as seismic facies. Walthers Law of Facies, or simply Walthers Law, named after the geologist Johannes Walther, conversely, it states that when a depositional environment migrates laterally, sediments of one depositional environment come to lie on top of another. In Russia the law is known as Golovkinsky-Walthers Law, honoring also Nikolai A. Golovkinsky, a classic example of this law is the vertical stratigraphic succession that typifies marine transgressions and regressions. The sequence of minerals that develop during progressive metamorphism define a facies series, seismic facies are mappable three-dimensional seismic units composed of reflection units whose parameters differ from adjacent facies units. Lithofacies Metamorphic rock Sequence stratigraphy Stratum
