1.
Makhtesh Ramon
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Makhtesh Ramon is a geological feature of Israels Negev desert. The crater is 40 km long, 2–10 km wide and 500 meters deep, the only settlement in the area is the small town of Mitzpe Ramon located on the northern edge of the crater. Today the crater and surrounding area forms Israels largest national park, hundreds of millions of years ago, the Negev desert was covered by an ocean. Slowly, this started to recede northwards leaving behind a hump-shaped hill, the hump was slowly flattened by water and climatic forces. Approximately five million years ago, the Arava Rift Valley was formed, with changing their courses. The crater bottom continued to deepen at a faster rate than the surrounding walls. As the crater deepened, more layers of ancient rock were exposed with rocks at the bottom of the crater being up to 200 million years old, Makhtesh Ramon contains a diversity of rocks including clay hills known for their fantastic red and yellow colors and forms. Limestone covered by basalt can also be found in smaller hills in the southern part of the makhtesh. Shen Ramon is a made of magma which hardened whilst underground. It later rose up through cracks in the Earths surface, and today stands in striking contrast with the nearby creamy coloured southern wall of the crater, as a black sharp-edged rock. In the centre of the makhtesh is HaMinsara, a low hill made up of columnar jointed sandstone - polygonal prismatic columns of quartzite, the pterioid bivalve Family Ramonalinidae is found in early Middle Triassic rocks of Makhtesh Ramon and was named after this feature. The Asian wild ass has been reintroduced to Makhtesh Ramon, in 1995 the population had increased to 40 adults in the area. The animals are hybrids of two different subspecies of the Asian Wild Ass and it is derived from the Turkmenian kulan and the Persian onager. The original subspecies, the Syrian wild ass, is completely extinct, other larger mammals of the area include Nubian ibexes, Dorcas gazelles, striped hyenas and few Arabian leopards. The ruins of a prehistoric stone structure known as Khan Saharonim are found in the makhtesh, as it lies along the ancient Incense Route. These ruins acted as a way station for the traders and their animals as they proceeded further westwards to the Mediterranean seaport city of Gaza, mazor, Emanuel and Krasnov, Boris, editors The Makhteshim Country - a Laboratory of Nature. Birds eye view of Ramon Crater
2.
Lamprophyre
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Lamprophyres are uncommon, small volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks and small intrusions. They are alkaline silica-undersaturated mafic or ultramafic rocks with high magnesium oxide, >3% potassium oxide, high sodium oxide and high nickel, lamprophyres occur throughout all geologic eras. Archaean examples are commonly associated with gold deposits. Cenozoic examples include magnesian rocks in Mexico and South America, modern science treats lamprophyres as a catch-all term for ultrapotassic mafic igneous rocks which have primary mineralogy consisting of amphibole or biotite, and with feldspar in the groundmass. They are classified under the IUGS Nomenclature for Igneous Rocks separately, for example, the TAS scheme is inappropriate due to the control of mineralogy by potassium, not by calcium or sodium. Classification schemes which include information, may be required to properly describe lamprophyres. Rock considered lamprophyres are part of a clan of rocks, with similar mineralogy, textures, lamprophyres are similar to lamproites and kimberlites. While modern concepts see orangeites, lamproites and kimberlites as separate, Mitchell considered the lamprophyres as a facies of igneous rocks created by a set of conditions. Either scheme may apply to some, but not all, occurrences and variations of the group of rocks known as lamprophyres. Rock considered lamprophyres to be derived from deep, volatile-driven melting in a subduction zone setting, others such as Mitchell consider them to be late offshoots of plutons, etc. though this can be difficult to reconcile with their primitive melt chemistry and mineralogy. Lamprophyres are a group of rocks containing phenocrysts, usually of biotite and amphibole, and pyroxene and they are thus distinguished from the porphyries and porphyrites in which the feldspar has crystallized in two generations. They are essentially dike rocks, occurring as dikes and thin sills and they are usually dark in color, owing to the abundance of ferro-magnesian silicates, of high specific gravity and liable to decomposition. For these reasons they have defined as a melanocrate series. Biotite and amphibole are panidiomorphic, all are euhedral, well formed, feldspar is restricted to the ground mass. In many lamprophyres the pale quartz and felspathic ingredients tend to occur in rounded spots, or ocelli and these spots may consist of radiate or brush-like feldspars or of quartz and feldspar. A central area of quartz or of analcite probably represents an original miarolitic cavity infilled at a later period, the presence or absence of the four dominant minerals, orthoclase, plagioclase, biotite and hornblende, determines the species, Minette contains biotite and orthoclase. Each variety of lamprophyre may and often contain all four minerals but is named according to the two which predominate. These rocks contain iron oxides, apatite, sometimes sphene, augite
3.
Shiprock
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Shiprock is a monadnock rising nearly 1,583 feet above the high-desert plain of the Navajo Nation in San Juan County, New Mexico, United States. Its peak elevation is 7,177 feet above sea level and it lies about 10.75 miles southwest of the town of Shiprock, which is named for the peak. Governed by the Navajo Nation, the formation is in the Four Corners region and plays a significant role in Navajo religion, myth, and tradition. It is located in the center of the occupied by the Ancient Pueblo People. Shiprock is a point of interest for rock climbers and photographers and has featured in several film productions. It is the most prominent landmark in northwestern New Mexico, the Navajo name for the peak, Tsé Bitʼaʼí, rock with wings or winged rock, refers to the legend of the great bird that brought the Navajo from the north to their present lands. The name Shiprock or Shiprock Peak or Ship Rock derives from the resemblance to an enormous 19th-century clipper ship. Americans first called the peak The Needle, a given to the topmost pinnacle by Captain J. F. McComb in 1860. United States Geological Survey maps indicate that the name Ship Rock dates from the 1870s, Shiprock is composed of fractured volcanic breccia and black dikes of igneous rock called minette. It is the remnant of the throat of a volcano. The rock probably was originally formed 2, 500–3,000 feet below the Earths surface, wall-like sheets of minette, known as dikes, radiate away from the central formation. Radiometric age determinations of the minette establish that these volcanic rocks solidified about 27 million years ago, Shiprock is in the northeastern part of the Navajo Volcanic Field—a field that includes intrusions and flows of minette and other unusual igneous rocks that formed about 25 million years ago. Agathla in Monument Valley is another prominent volcanic neck in this volcanic field, Shiprock and the surrounding land have religious and historical significance to the Navajo people. It is mentioned in many of their myths and legends, foremost is the peaks role as the agent that brought the Navajo to the southwest. According to one legend, after being transported from another place, one day, the peak was struck by lightning, obliterating the trail and leaving only a sheer cliff, and stranding the women and children on top to starve. The presence of people on the peak is forbidden for fear they might stir up the chį́įdii, Navajo legend puts the peak in a larger geographic context. Shiprock is said to be either a medicine pouch or a bow carried by the Goods of Value Mountain, the Chuska Mountains comprise the body, Chuska Peak is the head, the Carrizo Mountains are the legs, and Beautiful Mountain is the feet. Navajo legend has it that Bird Monsters nested on the peak, after Monster Slayer, elder of the Warrior Twins, destroyed Déélééd at Red Mesa, he killed two adult Bird Monsters at Shiprock and changed two young ones into an eagle and an owl
4.
Volcanic plug
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A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of pressure if rising volatile-charged magma is trapped beneath it, glacial erosion can lead to exposure of the plug on one side, while a long slope of material remains on the opposite side. Such landforms are called crag and tail, if a plug is preserved, erosion may remove the surrounding rock while the erosion-resistant plug remains, producing a distinctive upstanding landform. An example of two volcanic plugs can be found at the Pitons, in Saint Lucia, as they rise out of the eastern Caribbean Sea. Near the village of Rhumsiki in the Far North Province of Cameroon, spectacular volcanic plugs are present in the center of La Gomera island in the Canary Islands archipelago, within the Garajonay National Park. In New Zealands South Island, Ōnawe Peninsula on Banks Peninsula is a prominent volcanic plug, in Australia, the The Nut in Tasmania is a further example, along with Mount Warning. Borgarvirki is a volcanic plug located in north Iceland, a volcanic plug is situated in the town of Motta SantAnastasia in Italy. Saint Michel dAiguilhe chapel, whose construction started in 969, near Le Puy-en-Velay in France, the volcanic plug rises about 85 metres above the surroundings. Another building on a plug is the 14th century Trosky Castle in the Czech Republic. Rockall, a small, uninhabited, remote islet in the North Atlantic Ocean, is also a volcanic plug, in the United Kingdom, two examples of a building on a volcanic plug are the Castle Rock in Edinburgh, Scotland, and Deganwy Castle, Wales. The Law, Dundee, Ailsa Craig, Bass Rock, North Berwick Law, there are over 30 volcanic plugs in Northern Ireland, including Slemish in Ballymena, Tievebulliagh, Scawt Hill, Carrickarede, Scrabo and Slieve Gallion. Examples of volcanic plugs in the United States include Morro Rock, California and Laurel Hill, Devils Tower in Wyoming, as well as Little Devils Postpile located in Yosemite National Park, are also thought to be a volcanic plug by many geologists. Another example of a plug in the eastern USA is the highly eroded Starks Knob basaltic structure located along the Hudson River near Saratoga Springs. However, some geologists believe Starks Knob is not a plug at all, the origin of Devils Tower is not totally clear. Although it is admitted that it was formed by igneous intrusion, it is not necessarily a volcanic plug. In New Mexico, Shiprock is a further example, the Pitons of Saint Lucia, in the eastern Caribbean Sea are two volcanic plugs that rise abruptly out of the sea and are part of a UNESCO World Heritage site. The highest mountain plug rises to a height of nearly 760 metres, in Canada, the Castle Rock, located in British Columbia, is a volcanic plug that had volatile-charged magma still beneath it, leading to a Volcanic Explosivity Index 2 eruption
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.
Geology
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Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology also plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories, rock and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists also study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology, sedimentology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics also provided a mechanism for Alfred Wegeners theory of continental drift and they also provided a driving force for crustal deformation, and a new setting for the observations of structural geology
7.
Fracture (geology)
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A fracture is any separation in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. A fracture will form a deep fissure or crevice in the rock. Fractures are commonly caused by exceeding the rock strength, causing the rock to lose cohesion along its weakest plane. Fractures can provide permeability for fluid movement, such as water or hydrocarbons, highly fractured rocks can make good aquifers or hydrocarbon reservoirs, since they may possess both significant permeability and fracture porosity. Fractures are forms of brittle deformation, there are two types of primary brittle deformation processes. Shear fractures are the first initial breaks resulting from shear forces exceeding the strength in that plane. After those two initial deformations, several types of secondary brittle deformation can be observed, such as frictional sliding or cataclastic flow on reactivated joints or faults. Most often, fracture profiles will look like either a blade, ellipsoid, Fractures in rocks can be formed either due to compression or tension. Fractures due to include thrust faults. Fractures may also be a result from shear or tensile stress, some of the primary mechanisms are discussed below. First, there are three modes of fractures occur, Mode I crack – Opening mode Mode II crack – Sliding mode Mode III crack – Tearing mode For more information on this. This deformation creates propagation of fractures into previously unfractured rock, when the rock is subjected to tensile stress, in the case of a homogenous stress field, the crack will propagate in the direction perpendicular to the least principal stress. Engineers studying elasticity found that the due to a load distant from the region of interest is concentrated around material flaws. A. W. Griffith took this example and applied the concept of stress concentration to the ends of fractures, Griffith asserted that all material have microcracks or flaws where the stress concentration naturally occurs, and that these were the flaws where, under increasing stress, fractures propagate. As a result, these flaws were named Griffith cracks. From this assumption, tensile fracture development may be examined, the first form is in axial stretching. In this case, remote tensile stress is applied, allowing microcracks to open throughout the tensile region. As these cracks open up, the stresses at the crack tips intensify, eventually exceeding the rock strength and this can occur at times of rapid overburden erosion
8.
Intrusive rock
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Intrusive rock is formed when magma crystallizes and solidifies underground to form intrusions, for example plutons, batholiths, dikes, sills, laccoliths, and volcanic necks. Intrusive rock forms within Earths crust from the crystallization of magma, magma slowly pushes up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the magma slowly cools into a solid, the different parts of the magma crystallize into rocks, many mountain ranges, such as the Sierra Nevada in California, are formed mostly from large granite intrusions, see Sierra Nevada Batholith. Intrusions are one of the two ways igneous rock can form, the other is extrusive rock, that is, an eruption or similar event. Technically speaking, an intrusion is any formation of igneous rock, rock formed from magma that cools. In contrast, an extrusion consists of rock, rock formed above the surface of the crust. Large bodies of magma that solidify underground before they reach the surface of the crust are called plutons, plutonic rocks form 7% of the Earths current land surface. Coarse-grained intrusive igneous rocks form at depth within the earth are called abyssal while those that form near the surface are called subvolcanic or hypabyssal. The term intrusive suite seems near synonymous, there is, however, a modest difference, An intrusive suite is a group of plutons related in time and space. Intrusions vary widely, from mountain-range-sized batholiths to thin veinlike fracture fillings of aplite or pegmatite, when exposed by erosion, such batholiths may occupy large areas. A well-known example of an intrusion is Devils Tower, another is Shiprock, New Mexico, USA. Be the pluton is large, it may be called a batholith or a stock, Intrusive rocks are characterized by large crystal sizes, and as the individual crystals are visible, the rock is called phaneritic. This is as the magma cools underground, and while cooling may be fast or slow, cooling is slower than on the surface, if it runs parallel to rock layers, it is called a sill. If an intrusion makes rocks above rise to form a dome, as heat dissipation is slow, and as the rock is under pressure, crystals form, and no vitreous rapidly chilled matter is present. The intrusions did not flow while solidifying, hence do not show lines, contained gases could not escape through the thick strata, thus form cavities, which can often be observed. Because their crystals are of the rough equal size, these rocks are said to be equigranular, there is typically no distinction between a first generation of large well-shaped crystals and a fine-grained ground-mass. Earlier crystals originated at a time when most of the rock was still liquid and are more or less perfect, later crystals are less regular in shape because they were compelled to occupy the spaces left between the already-formed crystals. The former case is said to be idiomorphic, the latter is xenomorphic, there are also many other characteristics that serve to distinguish the members of these two groups
9.
Sedimentary rock
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Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earths surface and within bodies of water. Sedimentation is the name for processes that cause mineral and/or organic particles to settle in place. The particles that form a rock by accumulating are called sediment. Sedimentation may also occur as minerals precipitate from solution or shells of aquatic creatures settle out of suspension. The sedimentary rock cover of the continents of the Earths crust is extensive, sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding, sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores. The study of the sequence of rock strata is the main source for an understanding of the Earths history, including palaeogeography, paleoclimatology. The scientific discipline that studies the properties and origin of rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences, such as pedology, geomorphology, geochemistry, sedimentary rocks have also been found on Mars. Clastic sedimentary rocks are composed of rock fragments that were cemented by silicate minerals. Clastic rocks are composed largely of quartz, feldspar, rock fragments, clay minerals, and mica, any type of mineral may be present, 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, sand, and mud and this tripartite subdivision is mirrored by the broad categories of rudites, arenites, and lutites, respectively, in older literature. The subdivision of these three categories is based on differences in clast shape, conglomerates and breccias), composition. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel, 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. Clean sandstones with open 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. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles and these relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as the flow calms and the particles settle out of suspension
10.
Magma
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Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Magma often collects in magma chambers that may feed a volcano or solidify underground to form an intrusion, magma is capable of intruding into adjacent rocks, extrusion onto the surface as lava, and explosive ejection as tephra to form pyroclastic rock. Magma is a complex high-temperature fluid substance, temperatures of most magmas are in the range 700 °C to 1300 °C, but very rare carbonatite magmas may be as cool as 600 °C, and komatiite magmas may have been as hot as 1600 °C. Environments of magma formation and compositions are commonly correlated, environments include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Despite being found in such locales, the bulk of the Earths crust. Except for the outer core, most of the Earth takes the form of a rheid. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earths surface, magma compositions may evolve after formation by fractional crystallization, contamination, and magma mixing. By definition rock formed of solidified magma is called igneous rock, melting of solid rocks to form magma is controlled by three physical parameters, temperature, pressure, and composition. Mechanisms are discussed in the entry for igneous rock, as a rock melts, its volume changes. When enough rock is melted, the small globules of melt link up, under pressure within the earth, as little as a fraction of a percent partial melting may be sufficient to cause melt to be squeezed from its source. The degree of melting is critical for determining what type of magma is produced. The degree of partial melting required to form a melt can be estimated by considering the relative enrichment of incompatible elements versus compatible elements, incompatible elements commonly include potassium, barium, cesium, and rubidium. Rock types produced by small degrees of melting in the Earths mantle are typically alkaline. Typically, primitive melts of this composition form lamprophyre, lamproite, kimberlite and sometimes nepheline-bearing mafic rocks such as alkali basalts, pegmatite may be produced by low degrees of partial melting of the crust. Some granite-composition magmas are eutectic melts, and they may be produced by low to high degrees of melting of the crust. At high degrees of melting of the crust, granitoids such as tonalite, granodiorite and monzonite can be produced. Being only the time in recorded history that magma had been reached, IDDP decided to invest in the hole. A cemented steel case was constructed in the hole with a perforation at the close to the magma
11.
Sheet intrusion
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A sheet intrusion, or tabular intrusion, is a planar sheet of roughly the same thickness, that forms inside a pre-existing rock. When it cuts into another unlayered mass, or across layers, when it is formed between layers in a layered rock mass, it is called a sill. Thus the magma, intruded between existing rocks, solidifies into large sheets of igneous rock. They are among the most extensive igneous features on Earth, in the form of dikes, laccoliths, cone sheets, when limestone or other precipitate forms in a fault space, it is a sedimentary sheet intrusion. Crustal extension from exposed sheet intrusions, review and method proposal
12.
Clastic dike
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A clastic dike is a seam of sedimentary material that fills an open fracture in and cuts across sedimentary rock strata or layering in other rock types. Clastic dikes form rapidly by fluidized injection or passively by water, wind, diagenesis may play a role in the formation of some dikes. Clastic dikes are vertical or near-vertical. Centimeter-scale widths are common, but thicknesses range from millimetres to metres, length is usually many times width. Clastic dikes are found in sedimentary basin deposits worldwide, formal geologic reports of clastic dikes began to emerge in the early 19th century. Clastic dike environments include, Clastic dikes associated with earthquakes - An incredible variety of dikes is found in the geologic record, however, clastic dikes are typically produced by seismic disturbance and liquefaction of high water content sediments. Examples of this type are many, Clastic dikes are paleoseismic indicators in certain geologic settings. Several qualitative, field-based systems have developed to help distinguish seismites from soft sediment deformation features formed by non-seismic processes. Results from analytical modeling of clastic dike injection in soft rocks indicate propagation occurred at a rate of approximately 4 to 65 m/s at driving pressures of 1-2 MPa, emplacement duration is similar to the speed with which acoustic energy moves through partially lithified sedimentary rock. Clastic dikes associated with debris flows - Sandstone dikes formed by downward injection are found along Black Dragon wash upstream of the famous petroglyphs area, San Rafael Swell, Utah. Commonly, the fill is composed of grains, evidence that the injected material was lithified prior to impact and was crushed during injection into fractures. Clastic dikes associated with salt domes - Clastic dike swarms associated with salt dome diapirism are reported from the Dead Sea region, Clastic dikes associated with glaciers - Sand injection features are reported to have formed under heavy loads and confining pressures beneath grounding glacial ice. Clastic dikes in resistant bedrock - Though unusual, a significant number of reports describe sedimentary material intruding fractured crystalline bedrock, some of the articles referenced here describe lithified clastic dikes. Clastic dikes in storm deposits - Cyclic stresses from large waves can cause wet sediments to fluidize, tens of thousands of unusual clastic dikes penetrate sedimentary and bedrock units in the Columbia Basin of Washington, Oregon and Idaho. The dikes may be related to loading by outburst floods, other evidence suggests they are sediment-filled desiccation cracks. Some have suggested the dikes are ice wedge casts or features related to the melting of buried ice, earthquake shaking and liquefaction is invoked by others to explain the dikes. This action has taken place in open fissures, under water in fissures on the bed of the sea or other bodies of water, the filling from below has come about by pressure of some sort, in some cases undoubtedly hydrostatic
13.
Sediment
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For sediment in beverages, see dregs. For example, sand and silt can be carried in suspension in water and on reaching the sea be deposited by sedimentation. Sediments are most often transported by water, but also wind, beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of transport and deposition. Glacial moraine deposits and till are ice-transported sediments, sediment can be classified based on its grain size and/or its composition. Sediment size is measured on a log base 2 scale, called the Phi scale, composition of sediment can be measured in terms of, parent rock lithology mineral composition chemical make-up. This leads to an ambiguity in which clay can be used as both a size-range and a composition, sediment is transported based on the strength of the flow that carries it and its own size, volume, density, and shape. Stronger flows will increase the lift and drag on the particle, causing it to rise, rivers and streams carry sediment in their flows. This sediment can be in a variety of locations within the flow and these relationships are shown in the following table for the Rouse number, which is a ratio of sediment fall velocity to upwards velocity. If the upwards velocity is less than the settling velocity, but still high enough for the sediment to move, it will move along the bed as bed load by rolling, sliding. If the upwards velocity is higher than the velocity, the sediment will be transported high in the flow as wash load. As there are generally a range of different particle sizes in the flow, sediment motion can create self-organized structures such as ripples, dunes, antidunes on the river or stream bed. These bedforms are often preserved in rocks and can be used to estimate the direction. Overland flow can erode soil particles and transport them downslope, the erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions. If the initial impact of rain droplets dislodges soil, the phenomenon is called rainsplash erosion, if overland flow is directly responsible for sediment entrainment but does not form gullies, it is called sheet erosion. If the flow and the substrate permit channelization, gullies may form, glaciers carry a wide range of sediment sizes, and deposit it in moraines. The overall balance between sediment in transport and sediment being deposited on the bed is given by the Exner equation and this expression states that the rate of increase in bed elevation due to deposition is proportional to the amount of sediment that falls out of the flow. This can be localized, and simply due to obstacles, examples are scour holes behind boulders, where flow accelerates
14.
Lord Howe Island
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It is about 10 km long and between 0.3 and 2.0 km wide with an area of 14.55 km2, though just 3.98 km2 of that comprises the low-lying developed part of the island. Along the west coast there is a sandy semi-enclosed sheltered coral reef lagoon, most of the population lives in the north, while the south is dominated by forested hills rising to the highest point on the island, Mount Gower. The Lord Howe Island Group comprises 28 islands, islets and rocks, apart from Lord Howe Island itself the most notable of these is the volcanic and uninhabited Balls Pyramid about 23 km to the southeast of Howe. To the north lies the Admiralty Group, a cluster of seven uninhabited islands. On the return journey Ball sent a party ashore on Lord Howe Island to claim it as a British possession and it subsequently became a provisioning port for the whaling industry, and was permanently settled in June 1834. When whaling declined, the 1880s saw the beginning of the export of the endemic kentia palms. The other continuing industry, tourism, began after World War II ended in 1945, the islands standard time zone is UTC+10,30, or UTC+11 when daylight saving time applies. The currency is the Australian dollar, commuter airlines provide flights to Sydney, Brisbane, and Port Macquarie. UNESCO records the Lord Howe Island Group as a World Heritage Site of global natural significance, most of the island is virtually untouched forest, with many of the plants and animals found nowhere else in the world. The Lord Howe Island Act 1981 established a Permanent Park Preserve, the surrounding waters are a protected region designated the Lord Howe Island Marine Park. It appears that, prior to European discovery and settlement, Lord Howe Island was uninhabited, on the return journey of 13 March 1788 Ball observed Balls Pyramid and sent a party ashore on Lord Howe Island to claim it as a British possession. Numerous turtles and tame birds were captured and returned to Sydney, Ball named Mount Lidgbird and Balls Pyramid after himself and the main island after Richard Howe, First Earl Howe, who was First Lord of the Admiralty at the time. Watercolour sketches of native birds including the Lord Howe woodhen, white gallinule, as the latter two birds were soon hunted to extinction these paintings are their only remaining pictorial record. Over the next three years the Supply returned to the several times in search of turtles and the island was also visited by ships of the Second. The American fleet numbered 675 ships and Lord Howe was located in a known as the Middle Ground noted for sperm whales. Between July and October 1791 the Third Fleet ships arrived at Sydney, whale oil was to become Australias most profitable export until the 1830s, and it was the whaling industry that shaped Lord Howe Islands early history. They left three men, George Ashdown, James Bishop and Chapman, who were employed by a Sydney whaling firm to establish a supply station, the men were initially to provide meat by fishing and by raising pigs and goats from feral stock. They landed with their Māori wives and two Māori boys, huts were built in an area now known as Old Settlement which had a supply of fresh water, and a garden was established west of Blinky Beach
15.
Baranof Cross-Island Trail
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The Baranof Cross-Island Trail is an informal route across Baranof Island, Alaska from the community of Sitka to Baranof Warm Springs. The only section with a trail is from Medvejie to Camp Lake at 1,600, the route is popular among resident Sitkans, but also attracts visiting backpackers. From start to finish, the trail spans approximately 16 miles long, and 6,500 of elevation gain, but owing to the terrain covered. The usual direction of passage is west to east, or Sitka to Baranof Warm Springs, since Baranof Warm Springs has no permanent transportation options inbound or outbound, backpackers must either turn around and hike back to Sitka, or arrange float plane or boat transportation. The route begins at Medvejie Hatchery, accessible by boat or by hiking from Herring Cove on the 3. 5-mile private road to Medvejie Hatchery, the route climbs up Mount Bassie and crosses its western face and a small but crevasse-ridden icefield. Especially in the summer, when snow bridges have melted and blue ice is prevalent. An orbicular ridge leads north after Mount Bassie, splitting the Blue Lake watershed on the side of the island from the Baranof River watershed on the eastern side of the island. The geology of the offers many locations to make camp with access to small pools for drinking water. The ridge descends to two separate roughly mile-long icefields and these icefields are flat with a small rocky isthmus separating them. After the icefields, the route passes several lakes and descends down to Baranof Lake through a mix of temperate rainforest. An informal trail leads from Baranof Lake to the boardwalk of Baranof Warm Springs, an alternate route terminates on the southern side of Warm Springs Bay. It has increased opportunities for skiing in the winter and this route shares no common segments with the traditional route. This route begins with the approach to Peak 5390 and continues down past Mount Furuhelm, once at Warm Springs Bay, a pick-up to shuttle is required to cross the bay to Baranof Warm Springs. In the past ten years three separate parties have had to be rescued by the United States Coast Guard, including one near-death incident. The primary causes for complications on the trail are poor weather, poor decision-making after bad weather sets in, lack of equipment, there are currently no commercial guides, although such a venture has been planned in the past. Standard backpacking gear is required for a crossing, but also gear that accounts for alpine campsites exposed to high winds, ice axes and crampons are useful for traversing ice. Climbing rope, with or without harnesses, is suggested in case of exposure to crevasses, anchorage Daily News overview of rescue
16.
Alaska
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Alaska is a U. S. state located in the northwest extremity of North America. To the north are the Chukchi and Beaufort seas–the southern parts of the Arctic Ocean, the Pacific Ocean lies to the south and southwest. Alaska is the largest state in the United States by area, the 3rd least populous, approximately half of Alaskas residents live within the Anchorage metropolitan area. Alaskas economy is dominated by the fishing, natural gas, military bases and tourism are also a significant part of the economy. The United States purchased Alaska from the Russian Empire on March 30,1867, the area went through several administrative changes before becoming organized as a territory on May 11,1912. It was admitted as the 49th state of the U. S. on January 3,1959, the name Alaska was introduced in the Russian colonial period when it was used to refer to the peninsula. It was derived from an Aleut, or Unangam idiom, which refers to the mainland of Alaska. Literally, it means object to which the action of the sea is directed, Alaska is the northernmost and westernmost state in the United States and has the most easterly longitude in the United States because the Aleutian Islands extend into the Eastern Hemisphere. Alaska is the only non-contiguous U. S. state on continental North America and it is technically part of the continental U. S. but is sometimes not included in colloquial use, Alaska is not part of the contiguous U. S. often called the Lower 48. The capital city, Juneau, is situated on the mainland of the North American continent but is not connected by road to the rest of the North American highway system. Alaskas territorial waters touch Russias territorial waters in the Bering Strait, as the Russian Big Diomede Island, Alaska has a longer coastline than all the other U. S. states combined. Alaska is the largest state in the United States by total area at 663,268 square miles, over twice the size of Texas, Alaska is larger than all but 18 sovereign countries. Counting territorial waters, Alaska is larger than the area of the next three largest states, Texas, California, and Montana. It is also larger than the area of the 22 smallest U. S. states. Also referred to as the Panhandle or Inside Passage, this is the region of Alaska closest to the rest of the United States, as such, this was where most of the initial non-indigenous settlement occurred in the years following the Alaska Purchase. The region is dominated by the Alexander Archipelago as well as the Tongass National Forest and it contains the state capital Juneau, the former capital Sitka, and Ketchikan, at one time Alaskas largest city. The Alaska Marine Highway provides a vital transportation link throughout the area. The Interior is the largest region of Alaska, much of it is uninhabited wilderness, Fairbanks is the only large city in the region
17.
West Spanish Peak
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West Spanish Peak is a high and prominent mountain summit that is the higher of the two Spanish Peaks in the Rocky Mountains of North America. The summit of West Spanish Peak is the highest point in Las Animas County, the Spanish Peaks are two large igneous stocks which form an eastern outlier of the Culebra Range, a subrange of the Sangre de Cristo Mountains. West Spanish Peak is the easternmost 4000 meter mountain peak in the United States, due to its position well east of the Culebra Range and on the edge of the eastern plains of Colorado, West Spanish Peak enjoys great local vertical relief in almost all directions. For example, it rises over 6,000 ft in less than 6.5 miles on both its north and south flanks, though not a fourteener, West Spanish Peak is the twelfth most topographically prominent peak in the state. While the Spanish Peaks have the appearance of volcanic cones, they are actually stocks and they are surrounded by radiating dikes, up to 14 miles long, made of the same material. The standard ascent route for West Spanish Peak starts at Cordova Pass and it follows a trail for about 2 miles to treeline. From there, theres a path on talus up the southwest ridge of the peak for an additional 1.5 miles. The trail is very braided and has a tendency to go to the right, if climbers stay to the left and close to the ridge, the climbing is much easier. At about 13,000 is a large shale buttress to the right that usually has a pool of warm water at its foot. Once up on the part of the top ridge, its an easy hike to the actual summit. The top ridge tends to be 30–100 feet wide and is about 0.5 miles long before beginning a significant downward trend on the east side of the mountain, to the north and south are very steep descents. At the summit is a rock cairn with the usual PVC tube. This mountain is very unsafe when there is snow on the ground, best time to climb, early June through late October. Thunderstorm and lightning activity can be high in July, August, List of mountain peaks of North America List of mountain peaks of the United States List of mountain peaks of Colorado List of Colorado county high points West Spanish Peak on Summitpost
18.
Igneous rock
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Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava, the magma can be derived from partial melts of existing rocks in either a planets mantle or crust. Typically, the melting is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, Igneous and metamorphic rocks make up 90–95% of the top 16 km of the Earths crust by volume. Igneous rocks form about 15% of the Earths current land surface, most of the Earths oceanic crust is made of igneous rock. In terms of modes of occurrence, igneous rocks can be either intrusive or extrusive, the mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body, typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earths crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, the central cores of major mountain ranges consist of intrusive igneous rocks, usually granite. When exposed by erosion, these cores may occupy huge areas of the Earths surface, intrusive igneous rocks that form at depth within the crust are termed plutonic rocks and are usually coarse-grained. Intrusive igneous rocks that form near the surface are termed subvolcanic or hypabyssal rocks, hypabyssal rocks are less common than plutonic or volcanic rocks and often form dikes, sills, laccoliths, lopoliths, or phacoliths. Extrusive igneous rocks, also known as rocks, are formed at the crusts surface as a result of the partial melting of rocks within the mantle. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks and they are formed by the cooling of molten magma on the earths surface. The magma, which is brought to the surface through fissures or volcanic eruptions, hence such rocks are smooth, crystalline and fine-grained. Basalt is an extrusive igneous rock and forms lava flows, lava sheets. Some kinds of basalt solidify to form long polygonal columns, the Giants Causeway in Antrim, Northern Ireland is an example. The molten rock, with or without suspended crystals and gas bubbles, is called magma and it rises because it is less dense than the rock from which it was created. When magma reaches the surface from beneath water or air, it is called lava, eruptions of volcanoes into air are termed subaerial, whereas those occurring underneath the ocean are termed submarine. Black smokers and mid-ocean ridge basalt are examples of volcanic activity
19.
Aspect ratio
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The aspect ratio of a geometric shape is the ratio of its sizes in different dimensions. For example, the ratio of a rectangle is the ratio of its longer side to its shorter side – the ratio of width to height. The aspect ratio is expressed as two separated by a colon. The values x and y do not represent actual widths and heights but, rather, as an example,8,5,16,10 and 1.6,1 are three ways of representing the same aspect ratio. In objects of more than two dimensions, such as hyperrectangles, the ratio can still be defined as the ratio of the longest side to the shortest side. The term is most commonly used reference to, Graphic / image Image aspect ratio Display aspect ratio. A square has the smallest possible ratio of 1,1. An ellipse with a ratio of 1,1 is a circle. A circle has the minimal DWAR which is 1, a square has a DWAR of sqrt. The Cube-Volume Aspect Ratio of a set is the d-th root of the ratio of the d-volume of the smallest enclosing axes-parallel d-cube. A square has the minimal CVAR which is 1, a circle has a CVAR of sqrt. An axis-parallel rectangle of width W and height H, where W>H, has a CVAR of sqrt = sqrt, if the dimension d is fixed, then all reasonable definitions of aspect ratio are equivalent to within constant factors. Aspect ratios are mathematically expressed as x, y, in digital images there is a subtle distinction between the Display Aspect Ratio and the Storage Aspect Ratio, see Distinctions. Ratio Equidimensional ratios in 3D List of film formats Squeeze mapping Vertical orientation
20.
Fissure vent
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A fissure vent, also known as a volcanic fissure or eruption fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is often a few meters wide and may be many kilometers long, Fissure vents can cause large flood basalts which run first in lava channels and later in lava tubes. After some time the eruption builds up spatter resp, ash cones and may concentrate on one or some of them. Small fissure vents may not be discernible from the air. The dikes that feed fissures reach the surface from depths of a few kilometers and connect them to deeper magma reservoirs, fissures are usually found in or along rifts and rift zones, such as Iceland and the East African Rift. Fissure vents are often part of the structure of shield volcanoes, renewed eruptions generally occur from new parallel fractures offset by a few hundred to thousands of metres from the earlier fissures. This distribution of vents and sometimes voluminous eruptions of basaltic lava usually build up a thick lava plateau rather than a single volcanic edifice. The Laki fissures, part of the Grímsvötn volcanic system, produced one of the biggest effusive eruptions on earth in historical times, in the form of a flood basalt of 12–14 km³ of lava. During the Eldgjá eruption A. D. 934-40, another very big effusive fissure eruption in the system of Katla in South Iceland. In September 2014, an eruption is ongoing on the site of the 18th century lava field Holuhraun. The eruption is part of a series in the Bárðarbunga volcanic system. The radial fissure vents of Hawaiian volcanoes also produce “curtains of fire” as lava fountains erupting along a portion of a fissure and these vents build up low ramparts of basaltic spatter on both sides of the fissure. More isolated lava fountains along the fissure produce crater rows of small spatter and cinder cones, the fragments that form a spatter cone are hot and plastic enough to weld together, while the fragments that form a cinder cone remain separate because of their lower temperature. Media related to Eruption fissures at Wikimedia Commons Detailed list and KML files for Fissure Vents Volcanolive. com Page on Fissure Vents
21.
Stratum
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In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers. The stratum is the unit in a stratigraphic column and forms the basis of the study of stratigraphy. Each layer is one of a number of parallel layers that lie one upon another. They may extend over hundreds of thousands of kilometers of the Earths surface. Strata are typically seen as bands of different colored or differently structured material exposed in cliffs, road cuts, quarries, individual bands may vary in thickness from a few millimeters to a kilometer or more. Each band represents a mode of deposition, river silt, beach sand, coal swamp, sand dune, lava bed. Geologists study rock strata and categorize them by the material of beds, each distinct layer is typically assigned to the name of sheet, usually based on a town, river, mountain, or region where the formation is exposed and available for study. For example, the Burgess Shale is an exposure of dark, occasionally fossiliferous. Slight distinctions in material in a formation may be described as members, formations are collected into groups while groups may be collected into supergroups. Archaeological horizon Geologic formation Geologic map Geologic unit Law of superposition Bed GeoWhen Database
22.
Sill (geology)
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In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. The term sill is synonymous with concordant intrusive sheet and this means that the sill does not cut across preexisting rocks, in contrast to dikes, discordant intrusive sheets which do cut across older rocks. Sills are fed by dikes, except in locations where they form in nearly vertical beds attached directly to a magma source. These planes or weakened areas allow the intrusion of a thin body of magma paralleling the existing bedding planes, concordant fracture zone. Sills parallel beds and foliations in the country rock. They can be emplaced in a horizontal orientation, although tectonic processes may cause subsequent rotation of horizontal sills into near vertical orientations. Sills can be confused with solidified lava flows, however, there are differences between them. Intruded sills will show partial melting and incorporation of the country rock. On both contact surfaces of the rock into which the sill has intruded, evidence of heating will be observed. Lava flows will show this evidence only on the side of the flow. In addition, lava flows will show evidence of vesicles where gases escaped into the atmosphere. Because sills generally form at shallow depths below the surface, the pressure of overlying rock prevents this from happening much, lava flows will also typically show evidence of weathering on their upper surface, whereas sills, if still covered by country rock, typically do not. Certain layered intrusions are a variety of sill that often contain important ore deposits, phanerozoic examples are usually smaller and include the Rùm peridotite complex of Scotland and the Skaergaard igneous complex of east Greenland. These intrusions often contain concentrations of gold, platinum, chromium, despite their concordant nature, many large sills change stratigraphic level within the intruded sequence, with each concordant part of the intrusion linked by relatively short dike-like segments. Such sills are known as transgressive, examples include the Whin Sill, the geometry of large sill complexes in sedimentary basins has become clearer with the availability of 3D seismic reflection data. Such data has shown that many sills have a saucer shape. Sill may also refer to the rise in depth near the mouth of a fjord caused by the moraine of the previous glacier. Sill swarm Batholith Stock Dike Laccolith Sheet intrusion
23.
Dike swarm
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A dike swarm or dyke swarm is a large geological structure consisting of a major group of parallel, linear, or radially oriented dikes intruded within continental crust. They consist of several to hundreds of dikes emplaced more or less contemporaneously during a single intrusive event, such dike swarms may form a large igneous province and are the roots of a volcanic province. The occurrence of mafic dike swarms in Archean and Paleoproterozoic terrains is often cited as evidence for mantle plume activity associated with abnormally high mantle potential temperatures, dike swarms may extend over 400 km in width and length. The largest dike swarm known on Earth is the Mackenzie dike swarm in the half of the Canadian Shield in Canada. The number of giant dike swarms on Earth is small. However, the geometry of most giant dike swarms is poorly known due to their age. Dike swarms have also found on Venus and Mars
24.
Mackenzie dike swarm
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The Mackenzie dike swarm, also called the Mackenzie dikes, form a large igneous province in the western Canadian Shield of Canada. It is part of the larger Mackenzie Large Igneous Province and is one of more than three dozen dike swarms in various parts of the Canadian Shield. The mafic dikes cut Archean and Proterozoic rocks, including those in the Athabasca Basin in Saskatchewan, Thelon Basin in Nunavut, vast volumes of basaltic lava paved over a large area in the western Canadian Shield in the form of a flood basalt event. This massive eruptive event occurred during the Mesoproterozoic era about 1,267 million years ago. Today the thickness of these flood basalts range from 2,000 m to 3,500 m and consists of about 150 lava flows, each about 10 m to 25 m thick, which are part of the Copper Creek Formation. Except for the lowermost lava flows, which evidence of interaction with water. This basalt sequence has been called the Coppermine River Group and may have been contemporaneous with the Mackenzie dikes, the source for the Mackenzie dike swarm is considered to be a mantle plume center called the Mackenzie hotspot. About 1,268 million years ago, the Slave craton was partly uplifted and intruded by the giant Mackenzie dike swarm and this was the last major event to affect the core of the Slave craton, although later on some younger mafic magmatism registered along its edges
25.
Northwest Territories
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The Northwest Territories is a territory of Canada. At a land area of approximately 1,144,000 km2 and its estimated population as of 2016 is 44,291. Yellowknife became the capital in 1967, following recommendations by the Carrothers Commission. The Northwest Territories are bordered by Canadas two other territories, Nunavut to the east and Yukon to the west, and by the provinces of British Columbia, Alberta, and Saskatchewan to the south. The name is descriptive, adopted by the British government during the era to indicate where it lay in relation to Ruperts Land. It is shortened from North-Western Territory, in Inuktitut, the Northwest Territories are referred to as ᓄᓇᑦᓯᐊᖅ, beautiful land. There was some discussion of changing the name of the Northwest Territories after the splitting off of Nunavut, one proposal was Denendeh, as advocated by the former premier Stephen Kakfwi, among others. One of the most popular proposals for a new name – one to name the territory Bob – began as a prank, in the end a poll conducted prior to division showed that strong support remained to keep the name Northwest Territories. This name arguably became more appropriate following division than it had been when the territories extended far into Canadas north-central and it possibly meets Manitoba at a quadripoint to the extreme southeast, though surveys have not been completed. It has an area of 1,183,085 km2. Territorial islands in the Canadian Arctic Archipelago include Banks Island, Borden Island, Prince Patrick Island and its highest point is Mount Nirvana near the border with Yukon at an elevation of 2,773 m. The Northwest Territories extends for more than 1,300,000 km2 and has a large climate variant from south to north, the southern part of the territory has a subarctic climate, while the islands and northern coast have a polar climate. Summers in the north are short and cool, with highs in the mid teens Celsius. Winters are long and harsh, daytime highs in the mid −20 °C, extremes are common with summer highs in the south reaching 36 °C and lows reaching into the negatives. In winter in the south, it is not uncommon for the temperatures to reach −40 °C, in the north, temperatures can reach highs of 30 °C, and lows can reach into the low negatives. In winter in the north it is not uncommon for the temperatures to reach −50 °C, thunderstorms are not rare in the south. In the north they are rare, but do occur. Tornadoes are extremely rare but have happened with the most notable one happening just outside Yellowknife that destroyed a communications tower, the Territory has a fairly dry climate due to the mountains in the west
26.
Volcanic neck
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A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of pressure if rising volatile-charged magma is trapped beneath it, glacial erosion can lead to exposure of the plug on one side, while a long slope of material remains on the opposite side. Such landforms are called crag and tail, if a plug is preserved, erosion may remove the surrounding rock while the erosion-resistant plug remains, producing a distinctive upstanding landform. An example of two volcanic plugs can be found at the Pitons, in Saint Lucia, as they rise out of the eastern Caribbean Sea. Near the village of Rhumsiki in the Far North Province of Cameroon, spectacular volcanic plugs are present in the center of La Gomera island in the Canary Islands archipelago, within the Garajonay National Park. In New Zealands South Island, Ōnawe Peninsula on Banks Peninsula is a prominent volcanic plug, in Australia, the The Nut in Tasmania is a further example, along with Mount Warning. Borgarvirki is a volcanic plug located in north Iceland, a volcanic plug is situated in the town of Motta SantAnastasia in Italy. Saint Michel dAiguilhe chapel, whose construction started in 969, near Le Puy-en-Velay in France, the volcanic plug rises about 85 metres above the surroundings. Another building on a plug is the 14th century Trosky Castle in the Czech Republic. Rockall, a small, uninhabited, remote islet in the North Atlantic Ocean, is also a volcanic plug, in the United Kingdom, two examples of a building on a volcanic plug are the Castle Rock in Edinburgh, Scotland, and Deganwy Castle, Wales. The Law, Dundee, Ailsa Craig, Bass Rock, North Berwick Law, there are over 30 volcanic plugs in Northern Ireland, including Slemish in Ballymena, Tievebulliagh, Scawt Hill, Carrickarede, Scrabo and Slieve Gallion. Examples of volcanic plugs in the United States include Morro Rock, California and Laurel Hill, Devils Tower in Wyoming, as well as Little Devils Postpile located in Yosemite National Park, are also thought to be a volcanic plug by many geologists. Another example of a plug in the eastern USA is the highly eroded Starks Knob basaltic structure located along the Hudson River near Saratoga Springs. However, some geologists believe Starks Knob is not a plug at all, the origin of Devils Tower is not totally clear. Although it is admitted that it was formed by igneous intrusion, it is not necessarily a volcanic plug. In New Mexico, Shiprock is a further example, the Pitons of Saint Lucia, in the eastern Caribbean Sea are two volcanic plugs that rise abruptly out of the sea and are part of a UNESCO World Heritage site. The highest mountain plug rises to a height of nearly 760 metres, in Canada, the Castle Rock, located in British Columbia, is a volcanic plug that had volatile-charged magma still beneath it, leading to a Volcanic Explosivity Index 2 eruption
27.
Volcanic cone
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Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature, types of volcanic cones include stratocones, spatter cones, tuff cones, and cinder cones. Stratocones are large cone-shaped volcanoes made up of lava flows, explosively erupted pyroclastic rocks, unlike shield volcanoes, they are characterized by a steep profile and periodic, often alternating, explosive eruptions and effusive eruptions. Some have collapsed craters called calderas, the central core of a stratocone is commonly dominated by a central core of intrusive rocks that range from around 500 meters to over several kilometers in diameter. This central core is surrounded by generations of lava flows, many of which are brecciated. The typical stratocone is an andesitic to dacitic volcano that is associated with subduction zones and they are also known as either stratified volcano, composite cone, bedded volcano, cone of mixed type or Vesuvian-type volcano. A spatter cone is a low, steep-sided hill or mound that consists of welded lava fragments, called spatter, typically, spatter cones are about 3–5 meters high. In case of a fissure, lava fountaining will create broad embankments of spatter, called spatter ramparts. Spatter cones are circular and cone shaped, while spatter ramparts are linear wall-like features. Spatter cones and spatter ramparts are typically formed by lava fountaining associated with mafic, highly fluid lavas, as blobs of molten lava, spatter, are erupted into the air by a lava fountain, they can lack the time needed to cool completely before hitting the ground. Consequently, the spatter are not fully solid, like taffy, as they land, as a result, the spatter builds up a cone that is composed of spatter either agglutinated or welded to each other. They are characterized by rims that have a maximum relief of 100–800 meters above the crater floor. They typically have a rim to rim diameter of 300–5,000 meters, a tuff cone consists typically of thick-bedded pyroclastic flow and surge deposits created by eruption-fed density currents and bomb-scoria beds derived from fallout from its eruption column. The tuffs composing a tuff cone have commonly been altered, palagonitized, by either its interaction with groundwater or when it was deposited warm and wet. The pyroclastic deposits of tuff cones differ from the deposits of spatter cones by their lack or paucity of lava spatter, smaller grain-size. Typically, but not always, tuff cones lack associated lava flows and they are characterized by rims that have a low, broad topograhic profiles and gentle topographic slopes that are 25 degrees or less. The maximum thickness of the pyroclastic debris comprising the rim of a tuff ring is generally thin
28.
Diabase
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Diabase or dolerite or microgabbro is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine grained to aphanitic chilled margins which may contain tachylite. Diabase normally has a fine, but visible texture of euhedral lath-shaped plagioclase crystals set in a matrix of clinopyroxene, typically augite, with minor olivine, magnetite. Accessory and alteration minerals include hornblende, biotite, apatite, pyrrhotite, chalcopyrite, serpentine, chlorite, the texture is termed diabasic and is typical of diabases. This diabasic texture is also termed interstitial, the feldspar is high in anorthite, the calcium endmember of the plagioclase anorthite-albite solid solution series, most commonly labradorite. Diabase is usually found in relatively shallow intrusive bodies such as dikes. Diabase dikes occur in regions of crustal extension and often occur in swarms of hundreds of individual dikes or sills radiating from a single volcanic center. The Palisades Sill which makes up the New Jersey Palisades on the Hudson River, parts of the Deccan Traps of India, formed at the end of the Cretaceous also includes dolerite. It is also abundant in parts of Curaçao, an island off the coast of Venezuela. West of the Norseman–Wiluna Belt is the Yalgoo–Singleton Belt, where complex dolerite dike swarms obscure the volcaniclastic sediments, large dolerite sills such as the Golden Mile Dolerite can exhibit course grained texture, and show a large diversity in petrography and geochemistry across the width of the sill. The vast areas of mafic volcanism/plutonism associated with the Jurassic breakup of Gondwanaland in the Southern Hemisphere include many large diabase/dolerite sills and dike swarms. These include the Karoo dolerites of South Africa, the Ferrar Dolerites of Antarctica, in Tasmania dolerite dominates much of the landscape, particularly alpine areas. Ring dikes are large, near vertical dikes showing above ground as circular outcrops up to 30 km in diameter, thicker dikes are made up of plutonic rocks, rather than hypabyssal and are centred on deep intrusions. Diabase is crushed and used as an aggregate for road beds, buildings, railroad beds. Diabase can also be cut for use as as ornamental stone for countertops, facing stone on buildings, a form of dolerite, known as bluestone, is one of the materials used as in the construction of Stonehenge. In Tasmania, being one of the most common rocks found, it has used as a building stone, for landscaping. List of rock types Collection of dikes in the Fish River Canyon, Namibia
29.
Basalt
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Basalt is a common extrusive igneous rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of basalt flows. By definition, basalt is an igneous rock with generally 45-55% silica and less than 10% feldspathoid by volume. Basalt commonly features a very fine-grained or glassy matrix interspersed with visible mineral grains, the average density is 3.0 gm/cm3. Basalt is defined by its content and texture, and physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic minerals into hematite, although usually characterized as dark, basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured and these phenocrysts usually are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from the melt. Basalt with a texture is called vesicular basalt, when the bulk of the rock is mostly solid. Gabbro is often marketed commercially as black granite and these ultramafic volcanic rocks, with silica contents below 45% are usually classified as komatiites. Agricola applied basalt to the black rock of the Schloßberg at Stolpen. Tholeiitic basalt is relatively rich in silica and poor in sodium, included in this category are most basalts of the ocean floor, most large oceanic islands, and continental flood basalts such as the Columbia River Plateau. Basalt rocks are in some cases classified after their content in High-Ti and Low-Ti varieties. High-Ti and Low-Ti basalts have been distinguished in the Paraná and Etendeka traps and it has greater than 17% alumina and is intermediate in composition between tholeiite and alkali basalt, the relatively alumina-rich composition is based on rocks without phenocrysts of plagioclase. Alkali basalt is relatively poor in silica and rich in sodium and it is silica-undersaturated and may contain feldspathoids, alkali feldspar and phlogopite. Boninite is a form of basalt that is erupted generally in back-arc basins. Ocean island basalt Lunar basalt On Earth, most basalt magmas have formed by melting of the mantle. Basalt commonly erupts on Io, the third largest moon of Jupiter, and has formed on the Moon, Mars, Venus. The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below, the mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene
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Granite
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Granite is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Granites can be white, pink, or gray in color. The word granite comes from the Latin granum, a grain, in reference to the structure of such a holocrystalline rock. By definition, granite is a rock with at least 20% quartz. The term granitic means granite-like and is applied to granite and a group of igneous rocks with similar textures and slight variations in composition. Occasionally some individual crystals are larger than the groundmass, in case the texture is known as porphyritic. A granitic rock with a texture is known as a granite porphyry. Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks, petrographic examination is required for identification of specific types of granitoids. The extrusive igneous rock equivalent of granite is rhyolite, Granite is nearly always massive, hard and tough, and therefore it has gained widespread use throughout human history, and more recently as a construction stone. The average density of granite is between 2.65 and 2.75 g/cm3, its compressive strength usually lies above 200 MPa, and its viscosity near STP is 3–6 •1019 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C, it is reduced in the presence of water. Granite has poor primary permeability, but strong secondary permeability, true granite according to modern petrologic convention contains both plagioclase and alkali feldspars. When a granitoid is devoid or nearly devoid of plagioclase, the rock is referred to as alkali feldspar granite, when a granitoid contains less than 10% orthoclase, it is called tonalite, pyroxene and amphibole are common in tonalite. A granite containing both muscovite and biotite micas is called a binary or two-mica granite, two-mica granites are typically high in potassium and low in plagioclase, and are usually S-type granites or A-type granites. A worldwide average of the composition of granite, by weight percent, based on 2485 analyses. Much of it was intruded during the Precambrian age, it is the most abundant basement rock that underlies the relatively thin veneer of the continents. Outcrops of granite tend to form tors and rounded massifs, granites sometimes occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels. Granite often occurs as small, less than 100 km² stock masses
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Rhyolite
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Rhyolite is an igneous, volcanic rock, of felsic composition. It may have any texture from glassy to aphanitic to porphyritic, the mineral assemblage is usually quartz, sanidine and plagioclase. Biotite and hornblende are common accessory minerals and it is the extrusive equivalent to granite. Rhyolite can be considered as the equivalent to the plutonic granite rock. Due to their content of silica and low iron and magnesium contents, rhyolite melts are highly polymerized. They also occur as breccias or in volcanic plugs and dikes, rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. Slower cooling forms microscopic crystals in the lava and results in such as flow foliations, spherulitic, nodular. Some rhyolite is highly vesicular pumice, many eruptions of rhyolite are highly explosive and the deposits may consist of fallout tephra/tuff or of ignimbrites. Eruptions of rhyolite are relatively rare compared to eruptions of less felsic lavas, etsch Valley Vulcanite Group near Bolzano and the surrounding area Gréixer rhyolitic complex at Moixeró range Vosges Iceland, all active and extinct central volcanoes, e. g. g. Wichita Mountains within the Southern Oklahoma Aulacogen St, in North American pre-historic times, rhyolite was quarried extensively in eastern Pennsylvania in the United States. Among the leading quarries was the Carbaugh Run Rhyolite Quarry Site in Adams County, comendite List of rock types Pantellerite Thunderegg University of North Dakota description of rhyolite Information from rocks-rock. com
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Lithosphere
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A lithosphere is the rigid, outermost shell of a terrestrial-type planet or natural satellite that is defined by its rigid mechanical properties. On Earth, it is composed of the crust and the portion of the mantle that behaves elastically on time scales of thousands of years or greater. The outermost shell of a planet, the crust, is defined on the basis of its chemistry. Earths lithosphere includes the crust and the uppermost mantle, which constitute the hard, the lithosphere is subdivided into tectonic plates. The uppermost part of the lithosphere that chemically reacts to the atmosphere, hydrosphere and biosphere through the forming process is called the pedosphere. The lithosphere is underlain by the asthenosphere which is the weaker, hotter, the study of past and current formations of landscapes is called geomorphology. The concept of the lithosphere as Earth’s strong outer layer was described by A. E. H, love in his 1911 monograph Some problems of Geodynamics and further developed by Joseph Barrell, who wrote a series of papers about the concept and introduced the term lithosphere. The concept was based on the presence of significant gravity anomalies over continental crust and these ideas were expanded by Reginald Aldworth Daly in 1940 with his seminal work Strength and Structure of the Earth and have been broadly accepted by geologists and geophysicists. The temperature at which olivine begins to deform viscously is often used to set this isotherm because olivine is generally the weakest mineral in the upper mantle, the mantle part of the lithosphere consists largely of peridotite. The crust is distinguished from the mantle by the change in chemical composition that takes place at the Moho discontinuity. Oceanic lithosphere consists mainly of mafic crust and ultramafic mantle and is denser than continental lithosphere, oceanic lithosphere thickens as it ages and moves away from the mid-ocean ridge. This thickening occurs by conductive cooling, which converts hot asthenosphere into lithospheric mantle and causes the oceanic lithosphere to become increasingly thick, the thickness of the mantle part of the oceanic lithosphere can be approximated as a thermal boundary layer that thickens as the square root of time. H ∼2 κ t Here, h is the thickness of the mantle lithosphere, κ is the thermal diffusivity for silicate rocks. The age is equal to L/V, where L is the distance from the spreading centre of mid-oceanic ridge. Oceanic lithosphere is less dense than asthenosphere for a few tens of millions of years and this is because the chemically differentiated oceanic crust is lighter than asthenosphere, but thermal contraction of the mantle lithosphere makes it more dense than the asthenosphere. New oceanic lithosphere is constantly being produced at mid-ocean ridges and is recycled back to the mantle at subduction zones, geoscientists can directly study the nature of the subcontinental mantle by examining mantle xenoliths brought up in kimberlite, lamproite, and other volcanic pipes. The histories of these xenoliths have been investigated by many methods, such studies have confirmed that mantle lithospheres below some cratons have persisted for periods in excess of 3 billion years, despite the mantle flow that accompanies plate tectonics. Cryosphere Geosphere Kola Superdeep Borehole Plate tectonics Solid Earth Chernicoff, Stanley, Whitney, earths Crust, Lithosphere and Asthenosphere Crust and Lithosphere
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Pegmatite
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A pegmatite is a holocrystalline, intrusive igneous rock composed of interlocking phaneritic crystals usually larger than 2.5 cm in size, such rocks are referred to as pegmatitic. The word pegmatite derives from Homeric Greek, πεγνυμι, which means “to bind together”, in reference to the crystals of quartz. Most pegmatites are composed of quartz, feldspar and mica, having a similar composition as granite. Crystal size is the most striking feature of pegmatites, with usually over 5 cm in size. Individual crystals over 10 metres long have been found, and many of the worlds largest crystals were found within pegmatites and these include, spodumene, microcline, beryl, and tourmaline. Similarly, crystal texture and form within pegmatitic rock may be taken to extreme size, perthite feldspar within a pegmatite often shows gigantic perthitic texture visible to the naked eye. The single feature that is diagnostic to all pegmatites is their large size crystal components, Pegmatite bodies are usually of minor size compared to typical intrusive rock bodies. Pegmatite body size is on the order of magnitude of one to a few hundred meters, compared to typical igneous rocks they are rather inhomogeneous and may show zones with different mineral assemblages. Crystal size and mineral assemblages are usually oriented parallel to the rock or even concentric for pegmatite lenses. Crystal growth rates in pegmatite must be slow to allow gigantic crystals to grow within the confines and pressures of the Earths crust. The mineralogy of a pegmatite is in most cases dominated by some form of feldspar, often with mica and usually with quartz and this is because of the difficulty in counting and sampling mineral grains in a rock which may have crystals from centimeters to meters across. Garnet, commonly almandine or spessartine, is a common mineral within pegmatites intruding mafic, pegmatites associated with granitic domes within the Archaean Yilgarn Craton intruding ultramafic and mafic rocks contain red, orange and brown almandine garnet. Syenite pegmatites are quartz depleted and contain large feldspathoid crystals instead, Pegmatite is difficult to sample representatively due to the large size of the constituent mineral crystals. Often, bulk samples of some 50–60 kg of rock must be crushed to obtain a meaningful, hence, pegmatite is often characterised by sampling the individual minerals which comprise the pegmatite, and comparisons are made according to mineral chemistry. Occasionally, enrichment in the trace elements will result in crystallisation of equally unusual and rare minerals such as beryl, tourmaline, columbite, tantalite, zinnwaldite. Pegmatites are the source of lithium either as spodumene, lithiophyllite or usually from lepidolite. The primary source for caesium is pollucite, a mineral from a zoned pegmatite, the majority of the worlds beryllium is sourced from non-gem quality beryl within pegmatite. Tantalum, niobium, rare-earth elements are sourced from a few pegmatites worldwide, bismuth, molybdenum and tin have been won from pegmatite, but this is not yet an important source of these metals
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Metamorphic rock
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Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. The original rock is subjected to heat and pressure, causing profound physical and/or chemical change, the protolith may be a sedimentary, an igneous, or even an existing type of metamorphic rock. Metamorphic rocks make up a part of the Earths crust. They are classified by texture and by chemical and mineral assemblage and they may be formed simply by being deep beneath the Earths surface, subjected to high temperatures and the great pressure of the rock layers above it. They can form from tectonic processes such as continental collisions, which cause horizontal pressure and they are also formed when rock is heated up by the intrusion of hot molten rock called magma from the Earths interior. The study of rocks provides information about the temperatures and pressures that occur at great depths within the Earths crust. Some examples of rocks are gneiss, slate, marble, schist. Metamorphic minerals are those that only at the high temperatures and pressures associated with the process of metamorphism. These minerals, known as index minerals, include sillimanite, kyanite, staurolite, andalusite, and some garnet. Other minerals, such as olivines, pyroxenes, amphiboles, micas, feldspars, and quartz, may be found in metamorphic rocks and these minerals formed during the crystallization of igneous rocks. They are stable at temperatures and pressures and may remain chemically unchanged during the metamorphic process. However, all minerals are only within certain limits. The change in the size of the rock during the process of metamorphism is called recrystallization. Both high temperatures and pressures contribute to recrystallization, high temperatures allow the atoms and ions in solid crystals to migrate, thus reorganizing the crystals, while high pressures cause solution of the crystals within the rock at their point of contact. The layering within metamorphic rocks is called foliation, and it occurs when a rock is being shortened along one axis during recrystallization. This causes the platy or elongated crystals of minerals, such as mica and chlorite and this results in a banded, or foliated rock, with the bands showing the colors of the minerals that formed them. Textures are separated into foliated and non-foliated categories, foliated rock is a product of differential stress that deforms the rock in one plane, sometimes creating a plane of cleavage. For example, slate is a metamorphic rock, originating from shale
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Aplite
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Aplite is an intrusive igneous rock in which the mineral composition is the same as granite, but in which the grains are much finer, under 1 mm across. Quartz and feldspar are the dominant minerals, the term aplite or aplitic is often used as a textural term to describe veins of quartz and feldspar with a fine to medium-grain sugary texture. Aplites are usually very fine-grained, white, grey or pinkish, dykes and veins of aplite are commonly observed traversing granitic bodies, they occur also, though less frequently, in syenites, diorites, quartz-diabases and gabbros. Aplites usually have an affinity to the rocks they intrude. The essential components of aplites are quartz and alkali feldspar, microcline, crystallization has been apparently rapid, and the ingredients have solidified almost at the same time. Hence their crystals are rather imperfect and fit closely to one another in a sort of mosaic of nearly equi-dimensional grains. The aplites associated with diorites and quartz-diabases differ in minor respects from the common aplites which accompany granites, the accessory minerals of these rocks are principally oligoclase, muscovite, apatite and zircon. Biotite and all ferromagnesian minerals rarely appear in them, and never in considerable amounts, riebeckite-granites have close affinities to aplites, shown especially in the prevalence of alkali feldspars. Tourmaline also occurs in some aplites, the rocks of this group are very frequent in all areas where masses of granite are known. They form dykes and irregular veins, which may be only a few inches or many feet in diameter, less frequently, aplite forms stocks or bosses, or occupies the edges or irregular portions of the interior of outcrops of granite. Syenite-aplites consist mainly of feldspar, the diorite-aplites of plagioclase. In all cases, they bear the same relation to the parent masses, by increase of quartz, aplites pass gradually, in a few localities, through highly quartzose modifications into quartz veins. This article incorporates text from a now in the public domain, Chisholm, Hugh
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Bed (geology)
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In geology a bed is the smallest division of a geologic formation or stratigraphic rock series marked by well-defined divisional planes separating it from layers above and below. A bed is the smallest lithostratigraphic unit, usually ranging in thickness from a centimetre to several metres and distinguishable from beds above, beds can be differentiated in various ways, including rock or mineral type and particle size. The term is applied to sedimentary strata, but may also be used for volcanic flows or ash layers. In a quarry, a bedding is a used for a structure occurring in granite. Three kinds of beds are, parallel beds, cross beds, geological unit Lamination Stratigraphy Stratum Lamina, Laminaset, Bed and Bedset
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Chinle Formation
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The Chinle is controversially considered to be synonymous to the Dockum Group of eastern Colorado and New Mexico, western Texas, the Oklahoma panhandle, and southwestern Kansas. The Chinle is sometimes named as a formation within the Dockum Group in New Mexico. The Chinle Formation is part of the Colorado Plateau, Basin and Range, a probable separate depositional basin within the Chinle is found in northwestern Colorado and northeastern Utah. The southern portion of the Chinle reaches a thickness of a little over 520 m. Typically, the Chinle rests unconformably on the Moenkopi Formation, there is no designated type locality for this formation. United States Geological Survey economic geologist Raymond C, robeck in 1956 revised the unnamed members of Gregory by identifying and naming the Temple Mountain member as the basal-most unit in the area of the San Rafael Swell of Utah. In 1957 John H. Stewart revised the Shinarump Conglomerate of G. K. Gilbert,1875, and Edwin E. Howell,1875, and Gregory,1917, and renamed it the Shinarump member of the Chinle formation. An overview of the geology of the area was created by USGS geologist Forrest G. Poole, sikich revised the unit and assigned more members assigned in 1965. The areal extent of the unit was mapped by Wilson and Stewart in 1967, in 1972 the areal limits were modified and an overview created by Stewart and others. Kelley assigned more members and revised the unit in 1972, Lucas and Hayden did the same thing in 1989. The Rock Point Member was assigned by Dubiel in 1989, the Chinle was raised to group status by Lucas in 1993, thus also raising many of the members to formation status. He also included the formations of the Dockum Group of eastern New Mexico and this modified nomenclature is controversial, many still retain the Chinle as a formation and separate out the Dockum Group. The Dockum was named in 1890, before the Chinle, if Lucas is correct, his Chinle Group should be named the Dockum Group due to stratigraphic nomenclature rules. Overviews of the Chinle were created by Dubiel and others and Hintze, the formation members and their thicknesses are highly variable across the Chinle. The stratigraphically lowest formation is the Temple Mountain Member, however, in most areas, the basal member is the Shinarump Member. The Shinarump is a braided-river system channel-deposit facies, the Monitor Butte Member overlies the Shinarump in most areas. The Monitor Butte is an overbank facies with lacustrine deposits and this is overlain in western areas by the channel-deposit facies Moss Back Member. More commonly, the Monitor Butte grades into the Petrified Forest Member, the Petrified Forest is predominately overbank deposits with thin lenses of channel-deposit facies and lacustrine deposits
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Canyonlands National Park
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Canyonlands National Park is a U. S. National Park located in southeastern Utah near the town of Moab. It preserves a colorful landscape eroded into countless canyons, mesas, and buttes by the Colorado River, the Green River, legislation creating the park was signed into law by President Lyndon Johnson on September 12,1964. The park is divided into four districts, the Island in the Sky, the Needles, the Maze, while these areas share a primitive desert atmosphere, each retains its own character. Author Edward Abbey, a frequent visitor, described the Canyonlands as the most weird, wonderful, Canyonlands is a popular recreational destination. Since 2007, more than 400,000 people have visited the park each year with a record of 776,218 visitors in 2016, the geography of the park is well suited to a number of different recreational uses. Hikers, mountain bikers, backpackers, and four-wheelers all enjoy traveling the rugged, the White Rim Road traverses the White Rim Sandstone level of the park between the rivers and the Island in the Sky. Since 2015, day-use permits must be obtained before travelling on the White Rim Road due to the popularity of driving and bicycling along it. The park services intent is to provide a wilderness experience for all visitors while minimizing impacts on the natural surroundings. Rafters and kayakers float the calm stretches of the Green River, below the Confluence, Cataract Canyon contains powerful whitewater rapids, similar to those found in the Grand Canyon. However, since there is no large impoundment on the Colorado River above Canyonlands National Park, river flow through the Confluence is determined by snowmelt, not management. As a result, and in combination with Cataract Canyons unique graben geology, as of 2016, the Island in the Sky district, with its proximity to the Moab, Utah area, attracts 76.7 percent of total park visitors. The Needles district is the second most visited, drawing 20.7 percent of visitors, the remote Maze district accounts for only about 1.5 percent of visitors, while river rafters and other river users account for the remaining 1.1 percent of total park visitation. Political compromise at the time of the parks creation limited the area to an arbitrary portion of the Canyonlands basin. Conservationists hope to complete the park by bringing the boundaries up to the high sandstone rims that form the border of the Canyonlands landscape. The Colorado River and Green River combine within the park dividing it into three districts called the Island in the Sky, the Needles and the Maze, the Colorado River flows through Cataract Canyon below its confluence with the Green River. The area was home of the Ancestral Puebloans, of which many traces can be found. Although the items and tools used have been largely taken away by looters, some of their stone. The Ancestral Puebloans also left traces in the form of petroglyphs, the Maze district is located west of the Colorado and Green rivers, and is the least accessible section of the park, and one of the most remote and inaccessible areas of the United States
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Clay
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Clay is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to water content and become hard, brittle. Depending on the content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size, silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in size and other physical properties. The distinction between silt and clay varies by discipline, geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm, sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils Atterberg limits, ISO14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. These solvents, usually acidic, migrate through the rock after leaching through upper weathered layers. In addition to the process, some clay minerals are formed through hydrothermal activity. There are two types of deposits, primary and secondary. Primary clays form as residual deposits in soil and remain at the site of formation, secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with very low energy depositional environments such as large lakes. Depending on the source, there are three or four main groups of clays, kaolinite, montmorillonite-smectite, illite, and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a group within the phyllosilicates. There are approximately 30 different types of clays in these categories. Varve is clay with visible annual layers, which are formed by deposition of those layers and are marked by differences in erosion. This type of deposit is common in glacial lakes
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Pressure
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Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the relative to the ambient pressure. Various units are used to express pressure, Pressure may also be expressed in terms of standard atmospheric pressure, the atmosphere is equal to this pressure and the torr is defined as 1⁄760 of this. Manometric units such as the centimetre of water, millimetre of mercury, Pressure is the amount of force acting per unit area. The symbol for it is p or P, the IUPAC recommendation for pressure is a lower-case p. However, upper-case P is widely used. The usage of P vs p depends upon the field in one is working, on the nearby presence of other symbols for quantities such as power and momentum. Mathematically, p = F A where, p is the pressure, F is the normal force and it relates the vector surface element with the normal force acting on it. It is incorrect to say the pressure is directed in such or such direction, the pressure, as a scalar, has no direction. The force given by the relationship to the quantity has a direction. If we change the orientation of the element, the direction of the normal force changes accordingly. Pressure is distributed to solid boundaries or across arbitrary sections of normal to these boundaries or sections at every point. It is a parameter in thermodynamics, and it is conjugate to volume. The SI unit for pressure is the pascal, equal to one newton per square metre and this name for the unit was added in 1971, before that, pressure in SI was expressed simply in newtons per square metre. Other units of pressure, such as pounds per square inch, the CGS unit of pressure is the barye, equal to 1 dyn·cm−2 or 0.1 Pa. Pressure is sometimes expressed in grams-force or kilograms-force per square centimetre, but using the names kilogram, gram, kilogram-force, or gram-force as units of force is expressly forbidden in SI. The technical atmosphere is 1 kgf/cm2, since a system under pressure has potential to perform work on its surroundings, pressure is a measure of potential energy stored per unit volume. It is therefore related to density and may be expressed in units such as joules per cubic metre. Similar pressures are given in kilopascals in most other fields, where the prefix is rarely used
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Permafrost
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In geology, permafrost is ground, including rock or soil, at or below the freezing point of water 0 °C for two or more years. Most permafrost is located in high latitudes, but alpine permafrost may exist at altitudes in much lower latitudes. Ground ice is not always present, as may be in the case of nonporous bedrock, Permafrost accounts for 0. 022% of total water on earth and exists in 24% of exposed land in the Northern Hemisphere. It also occurs subsea on the shelves of the continents surrounding the Arctic Ocean, portions of which were exposed during the last glacial period. A global temperature rise of 1.5 °C above current levels would be enough to start the thawing of permafrost in Siberia, Permafrost is soil, rock or sediment that is frozen for more than two consecutive years. In areas not overlain by ice, it exists beneath a layer of soil, rock or sediment, in practice, this means that permafrost occurs at an average air temperature of -2 °C or colder. Active layer thickness varies with the season, but is 0.3 to 4 meters thick, in the Northern Hemisphere, 24% of the ice-free land area, equivalent to 19 million square kilometers, is more or less influenced by permafrost. Most of this area is found in Siberia, northern Canada, Alaska, beneath the active layer annual temperature swings of permafrost become smaller with depth. The deepest depth of permafrost occurs where geothermal heat maintains a temperature above freezing, above that bottom limit there may be permafrost, whose temperature doesnt change annually—isothermal permafrost. The extent of permafrost varies with the climate, today, a considerable area of the Arctic is covered by permafrost. Overlying permafrost is an active layer that seasonally thaws during the summer. Plant life can be supported only within the active layer since growth can occur only in soil that is fully thawed for some part of the year, thickness of the active layer varies by year and location, but is typically 0. 6–4 m thick. In areas of continuous permafrost and harsh winters, the depth of the permafrost can exceed 1,400 m, Permafrost can also store carbon, both as peat and as methane. Work investigating the permafrost carbon pool size estimates that 1400–1700 Gt of carbon is stored in the northern circumpolar permafrost region, while a recent study that includes stores of the Tibetan Plateau, estimates total carbon pools in the permafrost of the Northern Hemisphere to be 1832 Gt. This large carbon pool represents more carbon than currently exists in all living things, Permafrost typically forms in any climate where the mean annual air temperature is less than the freezing point of water. Exceptions are found in moist-wintered forest climates, such as in Northern Scandinavia and the North-Eastern part of European Russia west of the Urals, fossil cold anomalies in the Geothermal gradient in areas where deep permafrost developed during the Pleistocene persist down to several hundred metres. This is evident from temperature measurements in boreholes in North America, typically, the below-ground temperature varies less from season to season than the air temperature, with mean annual temperatures tending to increase with depth. Thus, if the annual air temperature is only slightly below 0 °C
42.
Groundwater
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Groundwater is the water present beneath Earths surface in soil pore spaces and in the fractures of rock formations. A unit of rock or a deposit is called an aquifer when it can yield a usable quantity of water. The depth at which pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from, and eventually flows to, the naturally, natural discharge often occurs at springs and seeps. Groundwater is also withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, Groundwater is hypothesized to provide lubrication that can possibly influence the movement of faults. It is likely that much of Earths subsurface contains some water, Groundwater may not be confined only to Earth. The formation of some of the landforms observed on Mars may have influenced by groundwater. There is also evidence that water may also exist in the subsurface of Jupiters moon Europa. Groundwater is often cheaper, more convenient and less vulnerable to pollution than surface water, therefore, it is commonly used for public water supplies. For example, groundwater provides the largest source of water storage in the United States. Underground reservoirs contain far more water than the capacity of all surface reservoirs and lakes in the US, many municipal water supplies are derived solely from groundwater. Polluted groundwater is less visible, but more difficult to clean up, than pollution in rivers, Groundwater pollution most often results from improper disposal of wastes on land. An aquifer is a layer of substrate that contains and transmits groundwater. When water can flow directly between the surface and the zone of an aquifer, the aquifer is unconfined. The deeper parts of unconfined aquifers are more saturated since gravity causes water to flow downward. The upper level of this layer of an unconfined aquifer is called the water table or phreatic surface. Below the water table, where in general all pore spaces are saturated with water, is the phreatic zone, substrate with low porosity that permits limited transmission of groundwater is known as an aquitard
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Batholith
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A batholith is a large emplacement of igneous intrusive rock that forms from cooled magma deep in the Earths crust. Batholiths are almost always made mostly of felsic or intermediate rock-types, such as granite, quartz monzonite, although they may appear uniform, batholiths are in fact structures with complex histories and compositions. Individual plutons are crystallized from magma that traveled toward the surface from a zone of partial melting near the base of the Earths crust, traditionally, these plutons have been considered to form by ascent of relatively buoyant magma in large masses called plutonic diapirs. Because the diapirs are liquified and very hot, they tend to rise through the native country rock, pushing it aside. Most diapirs do not reach the surface to form volcanoes, but instead slow down, cool, an alternate view is that plutons commonly are formed not by diapiric ascent of large magma diapirs, but rather by aggregation of smaller volumes of magma that ascended as dikes. A batholith is formed when many plutons converge to form an expanse of granitic rock. Some batholiths are mammoth, paralleling past and present subduction zones, one such batholith is the Sierra Nevada Batholith, which is a continuous granitic formation that makes up much of the Sierra Nevada in California. An even larger batholith, the Coast Plutonic Complex is found predominantly in the Coast Mountains of western Canada, a batholith is an exposed area of continuous plutonic rock that covers an area larger than 100 square kilometers. Areas smaller than 100 square kilometers are called stocks, however, the majority of batholiths visible at the surface have areas far greater than 100 square kilometers. These areas are exposed to the surface through the process of erosion accelerated by continental uplift acting over many tens of millions to hundreds of millions of years and this process has removed several tens of square kilometers of overlying rock in many areas, exposing the once deeply buried batholiths. Batholiths exposed at the surface are subjected to pressure differences between their former location deep in the earth and their new location at or near the surface. As a result, their crystal structure expands slightly over time and this manifests itself by a form of mass wasting called exfoliation. This form of weathering causes convex and relatively thin sheets of rock to slough off the surfaces of batholiths. The result is clean and rounded rock faces. A well-known result of this process is Half Dome, located in Yosemite Valley,4, pp. 4–11 Idaho Batholith The Cornubian Batholith
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Laccolith
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A laccolith is a sheet intrusion that has been injected between two layers of sedimentary rock. The pressure of the magma is high enough that the strata are forced upward. Laccoliths tend to form at shallow depths and are typically formed by relatively viscous magmas, such as those that crystallize to diorite, granodiorite. Cooling underground takes place slowly, giving time for crystals to form in the cooling magma. The surface rock above laccoliths often erodes away completely, leaving the mound of igneous rock. The term was first applied as laccolite by Grove Karl Gilbert after his study of intrusions of diorite in the Henry Mountains of Utah in about 1875, horizontal sheeted intrusions were fed by vertical intrusions. It is often difficult to reconstruct shapes of intrusions, for instance, Devils Tower in Wyoming was thought to be a volcanic neck, but study has revealed it to be an eroded laccolith. The rock would have had to very slowly so as to form the slender pencil-shaped columns of phonolite porphyry seen today. At other localities, such as in the Henry Mountains and other isolated mountain ranges of the Colorado Plateau, the small Barber Hill syenite-stock laccolith in Charlotte, Vermont, has several volcanic trachyte dikes associated with it. Molybdenite is also visible in outcrops on this exposed laccolith, in Big Bend Ranch State Park, at the southwesternmost visible extent of the Ouachita orogeny, lies the Solitario. One of the largest laccoliths in the United States is Pine Valley Mountain in the Pine Valley Mountain Wilderness area near St. George, there are many examples of possible laccoliths on the surface of the Moon. These igneous features may be confused with impact cratering
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Runamo
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Runamo is a cracked dolerite dike that was for centuries held to be a runic inscription and gave rise to a famous scholarly controversy in the 19th century. It is located 2.7 km from the church of Bräkne-Hoby in Blekinge, Sweden. For hundreds of people said it was possible to read an inscription. As early as the 12th century, the Danish chronicler Saxo Grammaticus reported in the introduction to his Gesta Danorum that the inscription was no longer legible being too worn down. There was considerable interest in the inscription during the Gothicismus of the early 19th century, the Swedish writer Esaias Tegnér referred to it in his unfinished poem on the giantess Gerðr and Axel who became bishop Absalon of Lund. In 1833, the Royal Danish Academy of Sciences and Letters sent an expedition led by an Icelandic professor at the University of Copenhagen named Finnur Magnússon, the mission was to explore the signs making use of geological and artistic expertise, including the geologist Johan Georg Forchhammer. At first, Finnur was unable to read the signs, but resolving to read them from right to left and by interpreting most of them as bind runes, he believed he discerned a poem. Finnurs report prompted the famous Swedish scientist Jöns Jacob Berzelius to undertake his own study in 1836, since then, it is generally considered to be a dolerite dike with cracks. Skånes historia, till Saxo och Skånelagen, Gesta Danorum, English Book I-IX, Online Medieval and Classical Library The article Runamo in Nationalencyklopedin. The article Runamo in Nordisk familjebok
