Inverted relief, inverted topography, or topographic inversion refers to landscape features that have reversed their elevation relative to other features. It most occurs when low areas of a landscape become filled with lava or sediment that hardens into material, more resistant to erosion than the material that surrounds it. Differential erosion removes the less resistant surrounding material, leaving behind the younger resistant material, which may appear as a ridge where there was a valley. Terms such as "inverted valley" or "inverted channel" are used to describe such features. Inverted relief has been observed on the surfaces of other planets as well as on Earth. For example, well-documented inverted topographies have been discovered on Mars. Several processes can cause the floor of a depression to become more resistant to erosion than its surrounding slopes and uplands: First, coarse-grained sediment, such as gravel, accumulates in the depression, i.e. a stream valley or lake basin. Next, wind erosion removes fine-grained sediments in areas adjacent to the depression.
This leaves behind the more resistant coarse-grained sediments as a hill or ridge, while the channel switches to a lower lying area. A fluvial valley might fill with volcanic material such as welded tuff pouring into it; this would resist erosion. Cementation of underlying sediments by minerals dissolved in water may occur in a depression. On Earth, this happens in stream valleys as the result of the formation of duricrusts, i.e. silcrete or ferricrete, by pedogenesis. Minerals for cementation can come from groundwater, it is thought that a low point like a valley focuses groundflow, so more water and cements move into it, this results in a greater degree of cementation. Again, the cemented sediments would resist erosion while the surrounding terrain is eroded away to create a ridge or hill. A classic example of inverted relief is Tuolumne County, California. Multiple lava flows filled an ancient fluvial valley that cut westward through the central Sierra Nevada range to the Central Valley about 10.5 million years ago.
These Miocene lava flows filled this ancient river valley with a thick sequence of potassium-rich trachyandesite lavas that are more resistant to erosion than the Mesozoic siltstone and other rock in which the valley was cut. Thus, subsequent differential erosion left these volcanic rocks as a sinuous ridge, which now stands well above landscape underlain by more eroded Mesozoic rocks. Inverted relief in the form of sinuous and meandering ridges, which are indicative of ancient, inverted fluvial channels, is argued to be evidence of water channels on the Martian surface in the past. An example is Miyamoto Crater, proposed in 2010 as a potential location to be searched for evidence of life on Mars. Other examples are shown in the photographs below. Exhumed river channel – A ridge of sandstone that remains when the softer flood plain mudstone is eroded away Groundwater on Mars Science Encyclopedia: Mountains - Inverted Topography Everything2.com: Topographic Inversion MarsToday.com: Inverted Topography of Huo Hsing Vallis MarsToday.com: NASA Mars Picture of the Day: Inverted channels NASA: Inverted Topography, Argentina Utah Geological Survey: Inverted Topography in the St. George Area of Washington County California State University Department of Geologial Sciences: View of table mountain on eastern edge of the Sierra Nevada
The Jurassic period was a geologic period and system that spanned 56 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era known as the Age of Reptiles; the start of the period was marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Pliensbachian-Toarcian extinction in the Early Jurassic, the Tithonian event at the end; the Jurassic period is divided into three epochs: Early and Late. In stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, Upper Jurassic series of rock formations; the Jurassic is named after the Jura Mountains within the European Alps, where limestone strata from the period were first identified. By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses: Laurasia to the north, Gondwana to the south; this created more coastlines and shifted the continental climate from dry to humid, many of the arid deserts of the Triassic were replaced by lush rainforests.
On land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds appeared during the Jurassic, having evolved from a branch of theropod dinosaurs. Other major events include the appearance of the earliest lizards, the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to an aquatic mode of life; the oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates. The chronostratigraphic term "Jurassic" is directly linked to the Jura Mountains, a mountain range following the course of the France–Switzerland border. During a tour of the region in 1795, Alexander von Humboldt recognized the limestone dominated mountain range of the Jura Mountains as a separate formation that had not been included in the established stratigraphic system defined by Abraham Gottlob Werner, he named it "Jura-Kalkstein" in 1799.
The name "Jura" is derived from the Celtic root *jor via Gaulish *iuris "wooded mountain", borrowed into Latin as a place name, evolved into Juria and Jura. The Jurassic period is divided into three epochs: Early and Late. In stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, Upper Jurassic series of rock formations known as Lias and Malm in Europe; the separation of the term Jurassic into three sections originated with Leopold von Buch. The faunal stages from youngest to oldest are: During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Jurassic North Atlantic Ocean was narrow, while the South Atlantic did not open until the following Cretaceous period, when Gondwana itself rifted apart. The Tethys Sea closed, the Neotethys basin appeared. Climates were warm, with no evidence of a glacier having appeared; as in the Triassic, there was no land over either pole, no extensive ice caps existed.
The Jurassic geological record is good in western Europe, where extensive marine sequences indicate a time when much of that future landmass was submerged under shallow tropical seas. In contrast, the North American Jurassic record is the poorest of the Mesozoic, with few outcrops at the surface. Though the epicontinental Sundance Sea left marine deposits in parts of the northern plains of the United States and Canada during the late Jurassic, most exposed sediments from this period are continental, such as the alluvial deposits of the Morrison Formation; the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus common, along with calcitic ooids, calcitic cements, invertebrate faunas with dominantly calcitic skeletons; the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, South America, Japan and the United Kingdom.
In Africa, Early Jurassic strata are distributed in a similar fashion to Late Triassic beds, with more common outcrops in the south and less common fossil beds which are predominated by tracks to the north. As the Jurassic proceeded and more iconic groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are neither well studied in Africa. Late Jurassic strata are poorly represented apart from the spectacular Tendaguru fauna in Tanzania; the Late Jurassic life of Tendaguru is similar to that found in western North America's Morrison Formation. During the Jurassic period, the primary vertebrates living in the sea were marine reptiles; the latter include ichthyosaurs, which were at the peak of their diversity, plesiosaurs and marine crocodiles of the families Teleosauridae and Metriorhynchidae. Numerous turtles could be found in rivers. In the invertebrate world, several new groups appeared, including rudists (a reef-formi
Colorado is a state of the Western United States encompassing most of the southern Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains. It is the 8th most extensive and 21st most populous U. S. state. The estimated population of Colorado was 5,695,564 on July 1, 2018, an increase of 13.25% since the 2010 United States Census. The state was named for the Colorado River, which early Spanish explorers named the Río Colorado for the ruddy silt the river carried from the mountains; the Territory of Colorado was organized on February 28, 1861, on August 1, 1876, U. S. President Ulysses S. Grant signed Proclamation 230 admitting Colorado to the Union as the 38th state. Colorado is nicknamed the "Centennial State" because it became a state one century after the signing of the United States Declaration of Independence. Colorado is bordered by Wyoming to the north, Nebraska to the northeast, Kansas to the east, Oklahoma to the southeast, New Mexico to the south, Utah to the west, touches Arizona to the southwest at the Four Corners.
Colorado is noted for its vivid landscape of mountains, high plains, canyons, plateaus and desert lands. Colorado is part of the western and southwestern United States, is one of the Mountain States. Denver is most populous city of Colorado. Residents of the state are known as Coloradans, although the antiquated term "Coloradoan" is used. Colorado is notable for its diverse geography, which includes alpine mountains, high plains, deserts with huge sand dunes, deep canyons. In 1861, the United States Congress defined the boundaries of the new Territory of Colorado by lines of latitude and longitude, stretching from 37°N to 41°N latitude, from 102°02'48"W to 109°02'48"W longitude. After 158 years of government surveys, the borders of Colorado are now defined by 697 boundary markers and 697 straight boundary lines. Colorado and Utah are the only states that have their borders defined by straight boundary lines with no natural features; the southwest corner of Colorado is the Four Corners Monument at 36°59'56"N, 109°2'43"W.
This is the only place in the United States where four states meet: Colorado, New Mexico and Utah. The summit of Mount Elbert at 14,440 feet elevation in Lake County is the highest point in Colorado and the Rocky Mountains of North America. Colorado is the only U. S. state that lies above 1,000 meters elevation. The point where the Arikaree River flows out of Yuma County and into Cheyenne County, Kansas, is the lowest point in Colorado at 3,317 feet elevation; this point, which holds the distinction of being the highest low elevation point of any state, is higher than the high elevation points of 18 states and the District of Columbia. A little less than half of Colorado is flat and rolling land. East of the Rocky Mountains are the Colorado Eastern Plains of the High Plains, the section of the Great Plains within Nebraska at elevations ranging from 3,350 to 7,500 feet; the Colorado plains are prairies but include deciduous forests and canyons. Precipitation averages 15 to 25 inches annually. Eastern Colorado is presently farmland and rangeland, along with small farming villages and towns.
Corn, hay and oats are all typical crops. Most villages and towns in this region boast both a grain elevator. Irrigation water is available from subterranean sources. Surface water sources include the South Platte, the Arkansas River, a few other streams. Subterranean water is accessed through artesian wells. Heavy use of wells for irrigation caused underground water reserves to decline. Eastern Colorado hosts considerable livestock, such as hog farms. 70% of Colorado's population resides along the eastern edge of the Rocky Mountains in the Front Range Urban Corridor between Cheyenne and Pueblo, Colorado. This region is protected from prevailing storms that blow in from the Pacific Ocean region by the high Rockies in the middle of Colorado; the "Front Range" includes Denver, Fort Collins, Castle Rock, Colorado Springs, Pueblo and other townships and municipalities in between. On the other side of the Rockies, the significant population centers in Western Colorado are the cities of Grand Junction and Montrose.
The Continental Divide of the Americas extends along the crest of the Rocky Mountains. The area of Colorado to the west of the Continental Divide is called the Western Slope of Colorado. West of the Continental Divide, water flows to the southwest via the Colorado River and the Green River into the Gulf of California. Within the interior of the Rocky Mountains are several large parks which are high broad basins. In the north, on the east side of the Continental Divide is the North Park of Colorado; the North Park is drained by the North Platte River, which flows north into Nebraska. Just to the south of North Park, but on the western side of the Continental Divide, is the Middle Park of Colorado, drained by the Colorado River; the South Park of Colorado is the region of the headwaters of the South Platte River. In southmost Colorado is the large San Luis Valley, where the headwaters of the Rio Grande are located; the valley sits between the Sangre De Cristo Mountains and San Juan Mountains, consists of large desert lands that run into the mountains.
The Rio Grande drains due south into New Mexico and Texas. Across the Sangre de Cristo Range to the east of the S
Oklahoma is a state in the South Central region of the United States, bordered by Kansas on the north, Missouri on the northeast, Arkansas on the east, Texas on the south, New Mexico on the west, Colorado on the northwest. It is the 28th-most populous of the fifty United States; the state's name is derived from the Choctaw words okla and humma, meaning "red people". It is known informally by its nickname, "The Sooner State", in reference to the non-Native settlers who staked their claims on land before the official opening date of lands in the western Oklahoma Territory or before the Indian Appropriations Act of 1889, which increased European-American settlement in the eastern Indian Territory. Oklahoma Territory and Indian Territory were merged into the State of Oklahoma when it became the 46th state to enter the union on November 16, 1907, its residents are known as Oklahomans, its capital and largest city is Oklahoma City. A major producer of natural gas and agricultural products, Oklahoma relies on an economic base of aviation, telecommunications, biotechnology.
Both Oklahoma City and Tulsa serve as Oklahoma's primary economic anchors, with nearly two thirds of Oklahomans living within their metropolitan statistical areas. With ancient mountain ranges, prairie and eastern forests, most of Oklahoma lies in the Great Plains, Cross Timbers, the U. S. Interior Highlands, a region prone to severe weather. More than 25 Native American languages are spoken in Oklahoma, ranking third behind Alaska and California. Oklahoma is on a confluence of three major American cultural regions and served as a route for cattle drives, a destination for Southern settlers, a government-sanctioned territory for Native Americans; the name Oklahoma comes from the Choctaw phrase okla humma meaning red people. Choctaw Nation Chief Allen Wright suggested the name in 1866 during treaty negotiations with the federal government on the use of Indian Territory, in which he envisioned an all-Indian state controlled by the United States Superintendent of Indian Affairs. Equivalent to the English word Indian, okla humma was a phrase in the Choctaw language that described Native American people as a whole.
Oklahoma became the de facto name for Oklahoma Territory, it was approved in 1890, two years after the area was opened to white settlers. The name of the state is Pawnee: Uukuhuúwa, Cayuga: Gahnawiyoˀgeh. In the Chickasaw language, the state is known as Oklahomma', in Arapaho as bo'oobe'. Oklahoma is the 20th-largest state in the United States, covering an area of 69,899 square miles, with 68,595 square miles of land and 1,304 square miles of water, it lies in the Great Plains near the geographical center of the 48 contiguous states. It is bounded on the east by Arkansas and Missouri, on the north by Kansas, on the northwest by Colorado, on the far west by New Mexico, on the south and near-west by Texas. Much of its border with Texas lies along a failed continental rift; the geologic figure defines the placement of the Red River. The Oklahoma panhandle's Western edge is out of alignment with its Texas border; the Oklahoma/New Mexico border is 2.1 miles to 2.2 miles east of the Texas line. The border between Texas and New Mexico was set first as a result of a survey by Spain in 1819.
It was set along the 103rd meridian. In the 1890s, when Oklahoma was formally surveyed using more accurate surveying equipment and techniques, it was discovered the Texas line was not set along the 103rd meridian. Surveying techniques were not as accurate in 1819, the actual 103rd meridian was 2.2 miles to the east. It was much easier to leave the mistake than for Texas to cede land to New Mexico to correct the surveying error; the placement of the Oklahoma/New Mexico border represents the true 103rd meridian. Cimarron County in Oklahoma's panhandle is the only county in the United States that touches four other states: New Mexico, Texas and Kansas. Oklahoma is between the Great Plains and the Ozark Plateau in the Gulf of Mexico watershed sloping from the high plains of its western boundary to the low wetlands of its southeastern boundary, its highest and lowest points follow this trend, with its highest peak, Black Mesa, at 4,973 feet above sea level, situated near its far northwest corner in the Oklahoma Panhandle.
The state's lowest point is on the Little River near its far southeastern boundary near the town of Idabel, which dips to 289 feet above sea level. Among the most geographically diverse states, Oklahoma is one of four to harbor more than 10 distinct ecological regions, with 11 in its borders—more per square mile than in any other state, its western and eastern halves, are marked by extreme differences in geographical diversity: Eastern Oklahoma touches eight ecological regions and its western half contains three. Although having fewer ecological regions Western Oklahoma contains many relic species. Oklahoma has four primary mountain ranges: the Ouachita Mountains, the Arbuckle Mountains, the Wichita Mountains, the Ozark Mountains. Contained within the U. S. Interior Highlands region, the Ozark and Ouachita Mountains are the only major mountainous region between the Rocky Mountains and the Appalachians. A portion of the Flint Hills stretches into north-central Oklahoma, near the state's eastern border, The Oklahoma Tourism & Recreation Department regards Cavanal Hill as the world's tallest hill.
The semi-arid high
A summit is a point on a surface, higher in elevation than all points adjacent to it. The topographic terms acme, apex and zenith are synonymous; the term top is used only for a mountain peak, located at some distance from the nearest point of higher elevation. For example, a big massive rock next to the main summit of a mountain is not considered a summit. Summits near a higher peak, with some prominence or isolation, but not reaching a certain cutoff value for the quantities, are considered subsummits of the higher peak, are considered part of the same mountain. A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top. Summit may refer to the highest point along a line, trail, or route; the highest summit in the world is Everest with height of 8844.43 m above sea level. The first official ascent was made by Sir Edmund Hillary, they reached the mountain`s peak in 1953. Whether a highest point is classified as a summit, a sub peak or a separate mountain is subjective; the UIAA definition of a peak is.
Otherwise, it's a subpeak. In many parts of the western United States, the term summit refers to the highest point along a road, highway, or railroad. For example, the highest point along Interstate 80 in California is referred to as Donner Summit and the highest point on Interstate 5 is Siskiyou Mountain Summit. A summit climbing differs from the common mountaineering. Summit expedition requires: 1+ year of training, a good physical shape, a special gear. Although a huge part of climber’s stuff can be left and taken at the base camps or given to porters, there is a long list of personal equipment. In addition to common mountaineers’ gear, Summit climbers need to take Diamox and bottles of oxygen. There are special requirements for crampons, ice axe, rappel device, etc. Geoid Hill – Landform that extends above the surrounding terrain Nadir Summit accordance Peak finder Summit Climbing Gear List
Plains Indians, Interior Plains Indians or Indigenous people of the Great Plains and Canadian Prairies are the Native American tribes and First Nation band governments who have traditionally lived on the greater Interior Plains in North America. Their historic nomadic culture and development of equestrian culture and resistance to domination by the government and military forces of Canada and the United States have made the Plains Indian culture groups an archetype in literature and art for American Indians everywhere. Plains Indians are divided into two broad classifications which overlap to some degree; the first group became a nomadic horse culture during the 18th and 19th centuries, following the vast herds of buffalo, although some tribes engaged in agriculture. These include the Blackfoot, Assiniboine, Comanche, Gros Ventre, Lakota, Plains Apache, Plains Cree, Plains Ojibwe, Sarsi and Tonkawa; the second group of Plains Indians were semi-sedentary, and, in addition to hunting buffalo, they lived in villages, raised crops, traded with other tribes.
These include the Arikara, Iowa, Kitsai, Missouria, Osage, Pawnee, Quapaw and the Santee Dakota and Yankton Dakota. Indigenous peoples of the Great Plains are separated into Northern and Southern Plains tribes. Nomadic tribes survived on hunting and gathering. People hunted the American Bison to make items used in everyday life, such as food, decorations, crafting tools and clothing; the tribes followed the seasonal migration of the bison. The Plains Indians lived in tipis because they were disassembled and allowed the nomadic life of following game; the Spanish explorer Francisco Vásquez de Coronado was the first European to describe the Plains Indian culture. While searching for a reputedly wealthy land called Quivira in 1541, Coronado came across the Querechos in the Texas panhandle; the Querechos were the people called Apache. According to the Spaniards, the Querechos lived "in tents made of the tanned skins of the cows, they dry the flesh in the sun, cutting it thin like a leaf, when dry they grind it like meal to keep it and make a sort of sea soup of it to eat....
They season it with fat. They empty a large gut and fill it with blood, carry this around the neck to drink when they are thirsty." Coronado described many common features of Plains Indians culture: skin tepees, travois pulled by dogs, Plains Indian Sign Language, staple foods such as jerky and pemmican. The Plains Indians found by Coronado had not yet obtained horses; when horses were obtained, the Plains tribes integrated them into their daily lives. People in the southwest began to acquire horses in the 16th century by trading or stealing them from Spanish colonists in New Mexico; as horse culture moved northward, the Comanche were among the first to commit to a mounted nomadic lifestyle. This occurred by the 1730s, when they had acquired enough horses to put all their people on horseback; the horse enabled the Plains Indians to gain their subsistence with relative ease from the limitless buffalo herds. Riders were able to travel faster and farther in search of bison herds and to transport more goods, thus making it possible to enjoy a richer material environment than their pedestrian ancestors.
For the Plains peoples, the horse became an item of prestige as well as utility. They were extravagantly fond of their horses and the lifestyle they permitted; the first Spanish conqueror to bring horses to the new world was Hernán Cortés in 1519. However, Cortés only brought about sixteen horses with his expedition. Coronado brought 558 horses with him on his 1539–1542 expedition. At the time, the Indians of these regions had never seen a horse, although they had heard of them from contacts with Indians in Mexico. Only two of Coronado's horses were mares, so he was unlikely to have been the source of the horses that Plains Indians adopted as the cornerstone of their culture. In 1592, Juan de Onate brought 7,000 head of livestock with him when he came north to establish a colony in New Mexico, his horse herd included mares as well as stallions. Pueblo Indians learned about horses by working for Spanish colonists; the Spanish attempted to keep knowledge of riding away from Native people, but nonetheless, they learned and some fled their servitude to their Spanish employers—and took horses with them.
Some horses were obtained through trade in spite of prohibitions against it. Other horses were captured by Native people. In all cases the horse was adopted into their culture and herds multiplied. By 1659, the Navajo from northwestern New Mexico were raiding the Spanish colonies to steal horses. By 1664, the Apache were trading captives from other tribes to the Spanish for horses; the real beginning of the horse culture of the plains began with the expulsion of the Spanish from New Mexico in 1680 when the victorious Pueblo people captured thousands of horses and other livestock. They traded many horses north to the Plains Indians. In 1683 a Spanish expedition into Texas found horses among Native people. In 1690, a few horses were found by the Spanish among the Indians living at the mouth of the Colorado River of Texas and the Caddo of eastern Texas had a sizeable number; the French explorer Claude Charles Du Tisne found 300 horses among the Wichita on the Verdigris River in 1719, but they were still not plentiful.
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of small particules and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes; the particles that form a sedimentary rock are called sediment, may be composed of geological detritus or biological detritus. Before being deposited, the geological detritus was formed by weathering and erosion from the source area, transported to the place of deposition by water, ice, mass movement or glaciers, which are called agents of denudation. Biological detritus was formed by bodies and parts of dead aquatic organisms, as well as their fecal mass, suspended in water and piling up on the floor of water bodies. Sedimentation may occur as dissolved minerals precipitate from water solution; the sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust.
Sedimentary rocks are only a thin veneer over a crust consisting of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata; the study of sedimentary rocks and rock strata provides information about the subsurface, useful for civil engineering, for example in the construction of roads, tunnels, canals or other structures. Sedimentary rocks are important sources of natural resources like coal, fossil fuels, drinking water or ores; the study of the sequence of sedimentary rock strata is the main source for an understanding of the Earth's history, including palaeogeography and the history of life. The scientific discipline that studies the properties and origin of sedimentary rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps with other disciplines in the Earth sciences, such as pedology, geomorphology and structural geology. Sedimentary rocks have been found on Mars. Sedimentary rocks can be subdivided into four groups based on the processes responsible for their formation: clastic sedimentary rocks, biochemical sedimentary rocks, chemical sedimentary rocks, a fourth category for "other" sedimentary rocks formed by impacts and other minor processes.
Clastic sedimentary rocks are composed of other rock fragments that were cemented by silicate minerals. Clastic rocks are composed of quartz, rock fragments, clay minerals, mica. Clastic sedimentary rocks, are subdivided according to the dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions: gravel and mud; the classification of clastic sedimentary rocks parallels this scheme. This tripartite subdivision is mirrored by the broad categories of rudites and lutites in older literature; the subdivision of these three broad categories is based on differences in clast shape, grain size or texture. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel. Sandstone classification schemes vary but most geologists have adopted the Dott scheme, which uses the relative abundance of quartz and lithic framework grains and the abundance of a muddy matrix between the larger grains.
Composition of framework grains The relative abundance of sand-sized framework grains determines the first word in a sandstone name. Naming depends on the dominance of the three most abundant components quartz, feldspar, or the lithic fragments that originated from other rocks. All other minerals are considered accessories and not used in the naming of the rock, regardless of abundance. Quartz sandstones have >90% quartz grains Feldspathic sandstones have <90% quartz grains and more feldspar grains than lithic grains Lithic sandstones have <90% quartz grains and more lithic grains than feldspar grainsAbundance of muddy matrix material between sand grains When sand-sized particles are deposited, the space between the grains either remains open or is filled with mud. "Clean" sandstones with open pore space are called arenites. Muddy sandstones with abundant muddy matrix are called wackes. Six sandstone names are possible using the descriptors for grain composition and the amount of matrix. For example, a quartz arenite would be composed of quartz grains and have little or no clayey matrix between the grains, a lithic wacke would have abundant lithic grains and abundant muddy matrix, etc.
Although the Dott classification scheme is used by sedimentologists, common names like greywacke and quartz sandstone are still used by non-specialists and in popular literature. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles; these fine-grained particles are transported by turbulent flow in water or air, deposited as the flow calms and the particles settle out of suspension. Most authors presently