It subdivides all time into named units of abstract time called—in descending order of duration— eons, eras, periods, epochs, and ages. ʃ i ˌ ɛr. The first rocks were laid down in Precambrian times, when the area around Yosemite National Park was on the edge of a very young North American continent. 54 billion years). Some parts of the country have sequences of sedimentary rocks from the Paleozoic, Mesozoic and Cenozoic as In geology and related fields, a stratum ( pl. [1] Some active volcanoes are located in Insular Italy . [citation needed] Fracture (geology) A fractured rock in the Eastern Cape in South Africa, a mechanism of brittle deformation in response to stress. The geological study of Antarctica has been greatly hindered by the fact that nearly all of the continent is continuously covered with a thick layer of ice. Geologic units and processes are investigated on a large scale to reach a synthesized picture of the geological development of the continent. In technical terms, it consists of symmetrical anticlines that intersect each other at In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation ( strain) in the rocks, and ultimately, to understand the stress Geology of the United States. Orthogonal joint sets on a bedding plane in flagstones, Caithness, Scotland. The Chaotian is a proposed time division of the geologic time scale. [1] It has a thickness of 2,900 kilometres (1,800 mi) [1] making up about 84% of Earth's volume. 05 Ga (4. This proposal defines the Chaotian eon as a Solar System -wide time between the initiation of planetary formation and the hypothesised collision of the trojan dwarf planet Geology of Oman. The geology of Africa is varied and complex, and gives rise to the wide variety of landscapes found across the continent. Geologically the Australian state of New South Wales consists of seven main regions: Lachlan Fold Belt, the Hunter-Bowen Orogeny or New England Orogen (NEO), the Delamerian Orogeny, the Clarence Moreton Basin, the Great Artesian Basin, the Sydney Basin, and the Murray Basin. [2] Detrital particles can consist of lithic fragments (particles of recognisable rock), or of monomineralic fragments (mineral grains). Older geologic research referred to this unit as the Diabase-Schist-Tuff Formation. Earth formed about 4. The island is an example of hotspot volcanism, [1] with mainly mafic volcanic and igneous rocks, together with smaller A klippe is a solitary outcrop of the nappe in the middle of autochthonous material. The area formed as a series of small island arcs, deep-ocean sediments and mafic oceanic crust accreted to the western The geology of Ghana is primarily very ancient crystalline basement rock, volcanic belts and sedimentary basins, affected by periods of igneous activity and two major orogeny mountain building events. Examples include the Morrison Formation, named for the town of Morrison, Colorado, and the Kaibab Limestone Petroleum geology: the study of sedimentary basins applied to the search for hydrocarbons (oil exploration). In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the The geology of Cameroon is almost universally Precambrian metamorphic and igneous basement rock, formed in the Archean as part of the Congo Craton and the Central African Mobile Zone and covered in laterite, recent sediments and soils. It is a multidisciplinary field that is closely related to engineering geology and, to a lesser extent, to environmental geography. [2] This is often caused by extensional forces pulling apart the crust. The region is part of the Ring of Fire: the subduction of the Pacific and Farallon Plates under the North American Plate is responsible Hydrogeology (hydro-meaning water, and -geology meaning the study of the Earth) is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust (commonly in aquifers). Lyell used the theory of uniformitarianism to describe how the Earth's surface was changing over time. The plume is believed to have caused the formation of Iceland itself, the island first appearing over the ocean surface about Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of celestial bodies such as planets and their moons, asteroids, comets, and meteorites. Iron: Greece has 200 small "soft" iron deposits and iron-nickel laterite 130 kilometers north of Athens with 200 million tons of ore. A tectonic window, or fenster (lit. Supergene processes include the predominance of meteoric water circulation (i. 5 billion-year history of the Earth, tectonic upheavals and colliding plates have raised great Conglomerate (geology) Boulder of conglomerate with cobble-sized clasts. Tilted layers of sedimentary rock in the Rolle Pass in the Dolomites, Trentino. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4. [1] Geology of Taiwan. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. Geology is the scientific study of the origin, history, and structure of the Earth. Strike and dip. [1] These planes of weakness are oriented parallel to stratification in sedimentary rocks. The enumeration of those geologic time units is based on stratigraphy, which is the correlation and classification of rock strata. It is the earlier of two subperiods of the Carboniferous period lasting from roughly 358. The Himalayan arc extends about 2,400 km (1,500 mi) from Nanga Parbat (8,138 m (26,699 ft)) by the Indus River in northern Pakistan Basement (geology) In geology, basement and crystalline basement are crystalline rocks lying above the mantle and beneath all other rocks and sediments. However, geologists have disagreed on dating with some indicating dates in the Middle Cambrian or Archean through Paleoproterozoic. The geology of Somaliland is very closely related to the geology of Somalia. Shear (geology) In geology, shear is the response of a rock to deformation usually by compressive stress and forms particular textures. 54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left Crust (geology) The internal structure of Earth. The geology of India is diverse. [1] Horsts are typically found together with grabens. Geologic history, stratigraphy and tectonics. It involves geophysical, geochemical, sedimentological and paleontological investigations of the ocean floor and coastal zone. Nebraska's sediments and sedimentary rocks lie atop a basement The geology of Scotland is unusually varied for a country of its size, with a large number of different geological features. The region experienced complicated tectonics during the Paleozoic, long-running shallow water conditions and then renewed uplift and erosion in the past several In geology, accretion is a process by which material is added to a tectonic plate at a subduction zone, frequently on the edge of existing continental landmasses. Conglomerate ( / kənˈɡlɒmərɪt /) is a clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel -size clasts. The geology of Italy includes mountain ranges such as the Alps and the Apennines formed from the uplift of igneous and primarily marine sedimentary rocks all formed since the Paleozoic. [1] There are three main geographical sub-divisions: the Highlands and Islands is a diverse area which lies to the north and west of the Highland Boundary Fault; the Central Lowlands is a rift valley mainly comprising Geology of New South Wales. In such a system the rock mass ( hanging wall block) that has been transported by movement along the thrust is called a Joint (geology) Horizontal joints in the sedimentary rocks of the foreground and a more varied set of joints in the granitic rocks in the background. Geology of Pennsylvania. [1] Historical geology examines the vastness of geologic time, measured in billions of years, and investigates changes in the Earth, gradual and sudden, over this deep time. This includes the subdisciplines of lunar geology, selenology, and martian geology, areology. Geology is the study of rocks in the Earth's crust. While isostatic response is important, an increase in the mean elevation of a region can only occur in response to Tertiary (/ ˈ t ɜːr. "window" in German ), is a geologic structure formed by erosion or normal faulting on a thrust system. Although mainly basalt, it also includes volcaniclastic conglomerate, dolerite, chert and chert limestone. Geology of India. People who study geology are called geologists . The oldest rocks in Sweden date to more than 2. The island of Taiwan was formed approximately 4 to 5 million years ago at a convergent boundary between the Philippine Sea Plate and the Eurasian Plate. Rock outcrops in the Hajar, Huqf and Dhofar Mountains are a point of interest for international geologists. 5 billion years ago in the Precambrian. [1] These rocks are older than 570 million years and sometimes date back to around 2 to 3. It is predominantly solid, but in geological time it behaves as a viscous fluid. [1] The main points that are discussed in the geology of Iran include the study of the geological and structural units or zones; stratigraphy; magmatism and igneous rocks; ophiolite series and ultramafic rocks; and orogenic events in Iran. Events that greatly shaped Ethiopian geology is the assembly and This list of geology awards is an index to articles on notable awards for geology, an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. The hemispheric view of Venus, as revealed by more than a decade of radar investigations culminating in the 1990–1994 Magellan mission, is centered at 180 degrees east longitude. This uplift dates from the late Miocene to the Pliocene. The Mississippian ( / ˌmɪsɪˈsɪpi. 5–10. [1] [2] In Australia, New Zealand and Cornwall, the activities of amateur geologists are called fossicking. [1] Geology of Madeira. 9 to 323. [4] Shield (geology) A shield is a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. The geology of Iceland is unique and of particular interest to geologists. Detritus (geology) Detritus ( / dəˈtraɪtəs /; adj. The exposed surface is approximately 410,000 km 2 . Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Shear can be homogeneous or non-homogeneous, and may be pure shear or simple shear. The geology of the Zion and Kolob canyons area includes nine known exposed formations, all visible in Zion National Park in the U. Over the 4. A sill is a concordant intrusive sheet, meaning that it does not cut The Maltese archipelago, situated between Sicily and Tunisia, was created through the uplift of sedimentary rocks. 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. Geology can also include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon Geology of Italy. Because it encompasses the former territory of British Somaliland, the region is historically better researched than former Italian Somaliland. " [1] Puerto Rico is composed of Jurassic to Eocene volcanic and plutonic rocks, which are overlain by younger Oligocene to recent carbonates and other sedimentary rocks. It was affected by the Pan-African orogeny, although the later Hercynian orogeny produced fewer changes and left the Maseta Domain, a large area of remnant Paleozoic massifs. [1] Prior to the publication of the International Geology of Morocco. detrital / dəˈtraɪtəl /) is particles of rock derived from pre-existing rock through weathering and erosion. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start of the Cenozoic Era, and extended to the beginning of the Quaternary glaciation at the end Rift. The original rocks were transformed to contorted schist and gneiss, making their Geologic formations are typically named after a permanent natural or artificial feature of the geographic area in which they were first described. [1] Specifically in sedimentology, a bed can be defined in one of two major ways. Cobble (geology) A cobble (sometimes a cobblestone) is a clast of rock defined on the Udden–Wentworth scale as having a particle size of 64–256 millimeters (2. 2 million years ago. Reverse and thrust faults shorten (horizontally) and thicken the crust. Tectonic uplift is the geologic uplift of Earth's surface that is attributed to plate tectonics. The African plate, accounting for the whole of north Africa, and the Somali plate, which accounts for the eastern side of mid and southern Africa. A conglomerate typically contains a matrix of finer-grained sediments, such as sand, silt Environmental geology, like hydrogeology, is an applied science concerned with the practical application of the principles of geology in the solving of environmental problems created by man. They are found in deserts and are natural formations (unlike salt evaporation ponds, which are artificial). Archean rocks of the Zerenda Group, including schist, diamond-bearing gneiss, eclogite and marble are found in the Kokchetav Massif in the Kazakh Uplands. A fracture will sometimes form a deep fissure or crevice in the rock. [2] Fissility is differentiated from scaly fabric in hand sample by the parting surfaces’ continuously In the Wellington Region, the Torlesse Composite Terrane is composed of two subterranes, the Rakaia Terrane (late Triassic to early Jurassic, 230-180 Ma), to the west of the Ruahine Ranges, and the Pahau Terrane (late Jurassic to early Cretaceous, 180-100 Ma), to the east. Plates in the crust of the earth, according to the plate tectonics theory. [1] The basement rocks lie below a sedimentary platform or cover, or more generally any The geology of Sweden is the regional study of rocks, minerals, tectonics, natural resources and groundwater in the country. First proposed in 2010 [1] as an eon, it is named after Chaos, the primeval void in Greek mythology. 1776 – James Keir suggests that some rocks, such The geology of North America is a subject of regional geology and covers the North American continent, the third-largest in the world. [3] The white rocks at left center are the gypsum and anhydrite carapace of the diapir. The geology of Ethiopia includes rocks of the Neoproterozoic East African Orogeny, Jurassic marine sediments and Quaternary rift -related volcanism. The African continent rests over two main plates. [1] There are several types of lineations, intersection lineations, crenulation lineations, mineral lineations and stretching lineations being the most common. liquid mantle). Somaliland is a de facto independent country within the boundaries that the international community recognizes as Somalia. 54 ± 0. The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Geologic time scale uses the principles and techniques of geology to work out the geological history of the Earth. [1] Supergene (geology) In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Only one-fifth of its surface area is exposed bedrock, the rest being covered by ice. water derived from precipitation) with concomitant oxidation and chemical weathering. . It includes rocks from every age from Proterozoic to Holocene and a large variety of different rock types is represented. In soils, true cohesion is caused by following: Electrostatic forces in stiff overconsolidated clays (which may be lost through weathering) Cementing by Fe 2 O 3, Ca C O 3, Na Cl, etc. In ancient geological time this shelf was part of Gondwana , which around 400 million years ago broke from what is now Africa and drifted westwards relative to Africa. Cohesion (geology) Cohesion is the component of shear strength of a rock or soil that is independent of interparticle friction . [1] [2] [3] Geology of Venus. [1] The geometry of the cave and blowhole along with tide levels and swell The geology of Antarctica covers the geological development of the continent through the Archean, Proterozoic and Phanerozoic eons . Rock hammer for scale. Planetary geology: the study of geosciences as it relates to other celestial bodies, namely planets and their moons. 5 billion years. In geology, a blowhole or marine geyser is formed as sea caves grow landward and upward into vertical shafts and expose themselves toward the surface, which can result in hydraulic compression of seawater that is released through a port from the top of the blowhole. e. The divisions of regional geology are drawn in different ways, but May 28, 2024 · The geologic time scale is the “calendar” for events in Earth history. 1743 – Dr Christopher Packe produces a geological map of south-east England. Horst (geology) In physical geography and geology, a horst is a raised fault block bounded by normal faults. Lineation field measurements are recorded as map lines with a plunge angle and azimuth. The basalt columns of the Giant's Causeway together with geologically significant sections of the adjacent coast have been Hoodoo (geology) A hoodoo (also called a tent rock, fairy chimney, or earth pyramid) is a tall, thin spire of rock formed by erosion. Radar global map of the surface of Venus. [3] Some geologists study minerals (mineralogist) and the useful substances the rocks contain such as ores and fossil fuels . Fissility (geology) In geology, fissility is the ability or tendency of a rock to split along flat planes of weakness (“parting surfaces”). Marine geology has strong ties to geophysics and to physical oceanography . It is shown on the geologic map with triangular teeth pointing toward the upthrown side of the fault. Aside from modern sediments and some rocks formed within the past 541 million years of the Phanerozoic Eon, along the coast, many of the rocks in Engineering geology is the application of geology to engineering study for the purpose of assuring that the geological factors regarding the location, design, construction, operation and maintenance of engineering works are recognized and accounted for. Complex orogeny mountain building events and other tectonic occurrences built up extensive metamorphic crystalline basement rock that Divisions in French Regional Geology. Pyrite is common near East Peloponesus and disseminated copper sulfides are common in veins in Western Macedonia. In this way, sand becomes sandstone, and gravel becomes conglomerate or breccia. Little is known about the history of the oldest exposed rocks in the area due to extensive metamorphism. In a boundary running the length of the island and continuing southwards, the Eurasian Plate is sliding under the Lineation (geology) Lineations in structural geology are linear structural features within rocks. The added material may be sediment, volcanic arcs, seamounts, oceanic crust or other igneous features. Typically, the term is restricted to a ridge created by the differential erosion of outcropping, steeply dipping (greater than 30–40°), homoclinal, and typically Cementation (geology) Cementation involves ions carried in groundwater chemically precipitating to form new crystalline material between sedimentary grains. [1] Engineering geologists provide geological and geotechnical recommendations, analysis Matrix (geology) Orthoclase phenocrysts within a finer-grained matrix of a granite porphyry. Image from the Kazakh Uplands in Balkhash District, Kazakhstan. state of Utah. It is usually distinguished from the underlying mantle by its chemical makeup; however, in the case of icy satellites, it may be distinguished based on its phase (solid crust vs. r i, ˈ t ɜː r. Each province has its own economic The Earth's mantle is a layer of silicate rock between the crust and the outer core. Different regions of the Indian subcontinent contain rocks belonging to different geologic periods, dating as far back as the Eoarchean Era. Malta forms the crest of a tilted block on the edge of the Malta Graben. Block view of a rift formed of three segments, showing the location of the accommodation zones between them at changes in fault location or polarity (dip direction) Gulf of Suez Rift showing main extensional faults. Together, these formations represent about 150 million years of mostly Mesozoic -aged sedimentation in that part of North America. S. The geology of Morocco formed beginning up to two billion years ago, in the Paleoproterozoic and potentially even earlier. [1] A fragment of detritus is called a clast. Other scales define a cobble's size differently. The sediment that formed the area first settled in the waters of a shallow sea Tectonic uplift. The geology of Venus is the scientific study of the surface, crust, and interior of the planet Venus. The history of geology is concerned with the development of the natural science of geology. 1760 – John Michell suggests earthquakes are caused by one layer of rocks rubbing against another. Shaded relief map of the United States, showing 10 geological provinces. [1] The geological history of the Earth follows the major geological events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers ( stratigraphy ). 01 × 10 24 kg is 67% the mass of the Earth. The regional geology of France is commonly divided into the Paris Basin, the Armorican Massif, the Massif Central, the Aquitaine Basin, the Pyrenees, the Alps, the Côte languedocienne, the Sillon rhodanien, the Massif des Vosges, the Massif Ardennais, the Alsace graben ( Rhine graben) and Flanders Basin. A salt pan forms by evaporation of a water pool, such as a lake or pond. The striation's direction reveals the movement direction in the fault plane. Geologists use stratigraphy and paleontology to find out the sequence of the events, and show the plants and animals which lived at Early sedimentation Proterozoic complex. i / TUR-shə-ree, TUR-shee-err-ee) is an obsolete term for the geologic period from 66 million to 2. ən / miss-ə-SIP-ee-ən, [5] also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. The matrix of an igneous rock consists of finer-grained, often microscopic, crystals in which larger crystals, called Copper: The Chalkidiki Peninsula has 15 million tons of copper. In geology, strike and dip is a measurement convention used to describe the plane orientation or attitude of a planar geologic feature. ʃ ə. The new pore-filling minerals forms "bridges" between original sediment grains, thereby binding them together. A dome is a feature in structural geology where a circular part of the Earth's surface has been pushed upward, tilting the pre-existing layers of earth away from the center. [3] The isle of Lampedusa is made up of an identical structure on the southwest side of this rift. [1] The geology of Nepal is dominated by the Himalaya, the highest, youngest and a very highly active mountain range. : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either bedding surfaces or bedding planes. They generally form within sedimentary rock and volcanic rock formations. [1] The exposed geology of the Yosemite area includes primarily granitic rocks with some older metamorphic rock. [1] [2] [3] The Falkland Islands are located on a projection of the Patagonian continental shelf. While a horst is lifted or remains stationary, the grabens on either side subside. 6 million years ago. [1] [2] Although the geo- prefix typically indicates topics of or relating to Earth, planetary geology is named as such for The Geology of Puerto Rico "can be divided into three major geologic provinces: The Cordillera Central, the Carbonate, and the Coastal Lowlands. The Coal Region of Northeastern Pennsylvania has abundant anthracite coal, a high-value energy source. Hoodoos typically consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the elements. Pennsylvania 's physiographic provinces. The three kilometer thick Aruba Lava Formation is the oldest unit on the island, from the Cretaceous, which is intruded by a tonalite pluton. Taiwan lies on the western edge of the Philippine Plate. Marine geology or geological oceanography is the study of the history and structure of the ocean floor. Historical geology or palaeogeology is a discipline that uses the principles and methods of geology to reconstruct the geological history of Earth. Greenland is the largest island on Earth. Madeira began to form more than 100 million years ago in the Early Cretaceous, although most of the island has formed in the last 66 million years of the Cenozoic, particularly in the Miocene and Pliocene. Historical geology. Major faults such as the Wellington Fault and Wairarapa Fault lie close Geology of Ethiopia. The rock record spans about 825 million years and includes at least three Sill (geology) Illustration showing the difference between a dike and a sill. [5] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. Subcategories. Amateur geology or rock collecting (also referred to as rockhounding in the United States and Canada) is the non-professional study and hobby of collecting rocks and minerals or fossil specimens from the natural environment. In geology, a striation is a groove, created by a geological process, on the surface of a rock or a mineral. Nebraska's landscape is dominated by surface features, soil and aquifers in loosely compacted sediments, with areas of the state where thick layers of sedimentary rock outcrop. The richly textured landscape of the United States is a product of the dueling forces of plate tectonics, weathering and erosion. Geology by country (211 C, 9 P) Geology by sea or ocean (6 C) A reverse fault (if steeply dipping) or thrust fault (if shallowly dipping) [1] is a fault where the fault plane dips toward the upthrown block. Its mass of 4. The geology of Ireland consists of the study of the rock formations on the island of Ireland. Tigray Escarpment in northern Ethiopia exposing the layers of the Ethiopia-Yemen Continental Flood Basalts. Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation is a book by the Scottish geologist Charles Lyell that was first published in 3 volumes from 1830 to 1833. Iceland lies on the divergent boundary between the Eurasian plate and the North American plate. The name consists of the geographic name plus either "Formation" or a descriptive name. 1 in), larger than a pebble and smaller than a boulder. A rock made predominantly of cobbles is termed a conglomerate. Geology – one of the Earth sciences – is the study of the Earth, with the general exclusion of present-day life, flow within the ocean, and the atmosphere. Salt pan (geology) Natural salt pans or salt flats are flat expanses of ground covered with salt and other minerals, usually shining white under the sun. In geology, the crust is the outermost solid shell of a planet, dwarf planet, or natural satellite. [3] Geology of Thailand. In structural geology, striations are linear furrows, or linear marks, generated from fault movement. The geology of Thailand includes deep crystalline metamorphic basement rocks, overlain by extensive sandstone, limestone, turbidites and some volcanic rocks. The field of geology encompasses the composition, structure, physical properties, and history of Earth's components, and the processes by which it is shaped. The geology of California is highly complex, with numerous mountain ranges, substantial faulting and tectonic activity, rich natural resources and a history of both ancient and comparatively recent intense geological activity. The geology of Oman includes varied landscapes which are a blend of its geological history, and its climate over the past few million years. The geology of the Pacific Northwest includes the composition (including rock, minerals, and soils ), structure, physical properties and the processes that shape the Pacific Northwest region of North America. The terms groundwater hydrology, geohydrology, and hydrogeology are often used interchangeably. It also lies above a hotspot, the Iceland plume. The geology of Greenland is dominated by crystalline rocks of the Precambrian Bed (geology) In geology, a bed is a layer of sediment, sedimentary rock, or volcanic rock "bounded above and below by more or less well-defined bedding surfaces". However, techniques such as remote sensing have begun to Fold on an island in King Oscar Fjord, thought to result from the Caledonian orogeny. Former sea bottom that raised during the 2013 Bohol earthquake - the water used to extend to the mangroves at right. The geology of the Falkland Islands is described in several publications. Some of the rocks are very deformed and altered. This somber, gray, almost featureless crystalline complex is composed of originally sedimentary and igneous rocks with large quantities of quartz and feldspar mixed in. In geology, a rift is a linear zone where the lithosphere is being pulled apart [1] [2] and is an example of extensional The geology of Nebraska is part of the broader geology of the Great Plains of the central United States. 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 along the direction of foliation in metamorphic rock. [2] First, Campbell [3] and Reineck and Singh [4] use the term bed to refer to a thickness An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics . [1] It looks at the processes which change the Earth's surface and rocks under the surface. A feature's strike is the azimuth of an imagined horizontal line across the plane, and its dip is the angle of inclination (or depression angle) measured downward from horizontal. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Himalaya is a type locality for the study of on-going continent-continent collision tectonics. This category has the following 33 subcategories, out of 33 total. The matrix or groundmass of a rock is the finer-grained mass of material in which larger grains, crystals, or clasts are embedded. Joints in the Almo Pluton, City of Rocks National In geology and geomorphology, a hogback or hog's back is a long, narrow ridge or a series of hills with a narrow crest and steep slopes of nearly equal inclination on both flanks. In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. 1746 – Jean-Étienne Guettard presents the first mineralogical map of France to the French Academy of Sciences. mp rv ml ug oc ax hv et sz nb