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51-591: The Paparoa Range is a mountain range in the West Coast region of New Zealand's South Island . It was the first New Zealand land seen by a European – Abel Tasman in 1642. Part of the range has the country's highest protection as a national park; the Paparoa National Park was established in 1987. Within that park, the Cave Creek disaster occurred in 1995. The Dutch explorer Abel Tasman

102-442: A petrographic microscope . Microstructural analysis finds application also in multi-scale statistical analysis, aimed to analyze some rock features showing scale invariance. Geologists use rock geometry measurements to understand the history of strain in rocks. Strain can take the form of brittle faulting and ductile folding and shearing. Brittle deformation takes place in the shallow crust, and ductile deformation takes place in

153-406: A changed structure. Elastic deformation refers to a reversible deformation. In other words, when stress on the rock is released, the rock returns to its original shape. Reversible, linear, elasticity involves the stretching, compressing, or distortion of atomic bonds. Because there is no breaking of bonds, the material springs back when the force is released. This type of deformation is modeled using

204-514: A combination of structural geology and geomorphology . In addition, areas of karst landscapes which reside atop caverns, potential sinkholes, or other collapse features are of particular importance for these scientists. In addition, areas of steep slopes are potential collapse or landslide hazards. Environmental geologists and hydrogeologists need to apply the tenets of structural geology to understand how geologic sites impact (or are impacted by) groundwater flow and penetration. For instance,

255-401: A fold axial plane is measured in strike and dip or dip and dip direction. Lineations are measured in terms of dip and dip direction, if possible. Often lineations occur expressed on a planar surface and can be difficult to measure directly. In this case, the lineation may be measured from the horizontal as a rake or pitch upon the surface. Rake is measured by placing a protractor flat on

306-637: A framework to analyze and understand global, regional, and local scale features. Structural geologists use a variety of methods to (first) measure rock geometries, (second) reconstruct their deformational histories, and (third) estimate the stress field that resulted in that deformation. Primary data sets for structural geology are collected in the field. Structural geologists measure a variety of planar features ( bedding planes , foliation planes , fold axial planes, fault planes , and joints), and linear features (stretching lineations, in which minerals are ductilely extended; fold axes; and intersection lineations,

357-430: A hydrogeologist may need to determine if seepage of toxic substances from waste dumps is occurring in a residential area or if salty water is seeping into an aquifer . Plate tectonics is a theory developed during the 1960s which describes the movement of continents by way of the separation and collision of crustal plates. It is in a sense structural geology on a planet scale, and is used throughout structural geology as

408-491: A letter (S A , for instance). In cases where there is a bedding-plane foliation caused by burial metamorphism or diagenesis this may be enumerated as S0a. If there are folds, these are numbered as F 1 , F 2 , etc. Generally the axial plane foliation or cleavage of a fold is created during folding, and the number convention should match. For example, an F 2 fold should have an S 2 axial foliation. Deformations are numbered according to their order of formation with

459-453: A linear relationship between stress and strain, i.e. a Hookean relationship. Where σ denotes stress, ϵ {\displaystyle \epsilon } denotes strain, and E is the elastic modulus , which is material dependent. The elastic modulus is, in effect, a measure of the strength of atomic bonds. Plastic deformation refers to non-reversible deformation. The relationship between stress and strain for permanent deformation

510-442: A material's resistance to cracking. During plastic deformation, a material absorbs energy until fracture occurs. The area under the stress-strain curve is the work required to fracture the material. The toughness modulus is defined as: Where σ U T S {\displaystyle \sigma _{UTS}} is the ultimate tensile strength, and ϵ f {\displaystyle \epsilon _{f}}

561-627: A mix of different orogenic expressions and terranes , for example thrust sheets , uplifted blocks , fold mountains, and volcanic landforms resulting in a variety of rock types . Most geologically young mountain ranges on the Earth's land surface are associated with either the Pacific Ring of Fire or the Alpide belt . The Pacific Ring of Fire includes the Andes of South America, extends through

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612-442: A rake, and annotated as to the indication of throw on the fault. Generally it is easier to record strike and dip information of planar structures in dip/dip direction format as this will match all the other structural information you may be recording about folds, lineations, etc., although there is an advantage to using different formats that discriminate between planar and linear data. The convention for analysing structural geology

663-440: A subscript S, for example L s1 to differentiate them from intersection lineations, though this is generally redundant. Stereographic projection is a method for analyzing the nature and orientation of deformation stresses, lithological units and penetrative fabrics wherein linear and planar features (structural strike and dip readings, typically taken using a compass clinometer ) passing through an imagined sphere are plotted on

714-431: A two-dimensional grid projection, facilitating more holistic analysis of a set of measurements. Stereonet developed by Richard W. Allmendinger is widely used in the structural geology community. On a large scale, structural geology is the study of the three-dimensional interaction and relationships of stratigraphic units within terranes of rock or geological regions. This branch of structural geology deals mainly with

765-475: Is a critical part of engineering geology , which is concerned with the physical and mechanical properties of natural rocks. Structural fabrics and defects such as faults, folds, foliations and joints are internal weaknesses of rocks which may affect the stability of human engineered structures such as dams , road cuts, open pit mines and underground mines or road tunnels . Geotechnical risk, including earthquake risk can only be investigated by inspecting

816-406: Is a measure of the elastic energy absorbed of a material under stress. In other words, the external work performed on a material during deformation. The area under the elastic portion of the stress-strain curve is the strain energy absorbed per unit volume. The resilience modulus is defined as: where σ y {\displaystyle \sigma _{y}} is the yield strength of

867-423: Is absolute. Dip direction is measured in 360 degrees, generally clockwise from North. For example, a dip of 45 degrees towards 115 degrees azimuth, recorded as 45/115. Note that this is the same as above. The term hade is occasionally used and is the deviation of a plane from vertical i.e. (90°-dip). Fold axis plunge is measured in dip and dip direction (strictly, plunge and azimuth of plunge). The orientation of

918-538: Is at work while the mountains are being uplifted until the mountains are reduced to low hills and plains. The early Cenozoic uplift of the Rocky Mountains of Colorado provides an example. As the uplift was occurring some 10,000 feet (3,000 m) of mostly Mesozoic sedimentary strata were removed by erosion over the core of the mountain range and spread as sand and clays across the Great Plains to

969-444: Is becoming increasingly important. 2D and 3D models of structural systems such as anticlines, synclines, fold and thrust belts, and other features can help better understand the evolution of a structure through time. Without modeling or interpretation of the subsurface, geologists are limited to their knowledge of the surface geological mapping. If only reliant on the surface geology, major economic potential could be missed by overlooking

1020-420: Is nonlinear. Stress has caused permanent change of shape in the material by involving the breaking of bonds. One mechanism of plastic deformation is the movement of dislocations by an applied stress. Because rocks are essentially aggregates of minerals, we can think of them as poly-crystalline materials. Dislocations are a type of crystallographic defect which consists of an extra or missing half plane of atoms in

1071-480: Is the strain at failure. The modulus is the maximum amount of energy per unit volume a material can absorb without fracturing. From the equation for modulus, for large toughness, high strength and high ductility are needed. These two properties are usually mutually exclusive. Brittle materials have low toughness because low plastic deformation decreases the strain (low ductility). Ways to measure toughness include: Page impact machine and Charpy impact test . Resilience

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1122-413: Is the study of the three-dimensional distribution of rock units with respect to their deformational histories. 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 field that resulted in the observed strain and geometries. This understanding of

1173-437: Is to identify the planar structures , often called planar fabrics because this implies a textural formation, the linear structures and, from analysis of these, unravel deformations . Planar structures are named according to their order of formation, with original sedimentary layering the lowest at S0. Often it is impossible to identify S0 in highly deformed rocks, so numbering may be started at an arbitrary number or given

1224-441: Is uniform in composition and structure, then the surface of the material is only a few atomic layers thick, and measurements are of the bulk material. Thus, simple surface measurements yield information about the bulk properties. Ways to measure hardness include: Indentation hardness is used often in metallurgy and materials science and can be thought of as resistance to penetration by an indenter. Toughness can be described best by

1275-551: The Annamite Range . If the definition of a mountain range is stretched to include underwater mountains, then the Ocean Ridge forms the longest continuous mountain system on Earth, with a length of 65,000 kilometres (40,400 mi). The position of mountain ranges influences climate, such as rain or snow. When air masses move up and over mountains, the air cools, producing orographic precipitation (rain or snow). As

1326-1097: The Buller Gorge is a geological continuation of the Paparoa Range. The southern part of the range is located in Grey District and the northern part in Buller District . Some of the peaks are on the boundary of the two districts. Many of the named peaks commemorate scientists, with this theme started by Julius von Haast . These include the Buckland Peaks (named after William Buckland ), Mount Faraday ( Michael Faraday ; named by von Haast), Mount Curie ( Marie Curie ), Mount Mendel ( Gregor Mendel ), Mount Pasteur ( Louis Pasteur ), Mount Einstein ( Albert Einstein ), Mount Rutherford ( Ernest Rutherford ), Mount Euclid ( Euclid ), Mount Fleming ( Alexander Fleming ), Mount Lavoisier ( Antoine Lavoisier ), Mount Kelvin ( William Thomson, 1st Baron Kelvin ; named by

1377-575: The Mithrim Montes and Doom Mons on Titan, and Tenzing Montes and Hillary Montes on Pluto. Some terrestrial planets other than Earth also exhibit rocky mountain ranges, such as Maxwell Montes on Venus taller than any on Earth and Tartarus Montes on Mars . Jupiter's moon Io has mountain ranges formed from tectonic processes including the Boösaule , Dorian, Hi'iaka and Euboea Montes . Structural geology Structural geology

1428-848: The North American Cordillera , the Aleutian Range , on through Kamchatka Peninsula , Japan , Taiwan , the Philippines , Papua New Guinea , to New Zealand . The Andes is 7,000 kilometres (4,350 mi) long and is often considered the world's longest mountain system. The Alpide belt stretches 15,000 km across southern Eurasia , from Java in Maritime Southeast Asia to the Iberian Peninsula in Western Europe , including

1479-581: The Paparoa Range, as well as lower slopes and valleys below. One of the significant understory elements of the floral palette is the fern Blechnum discolor . It is located along the coast between the Buller and Grey Rivers, with the Inangahua River to the east. The highest peak in the Paparoa Range is Mount Uriah at 1,525 m (5,003 ft), and a number of other peaks are higher than 1,200 m (3,900 ft). The Papahaua Range north of

1530-767: The Paparoa Range, with the Blackball Branch/Roa Incline and the Rewanui Branch railways built to provide access to the mines. Although these branch lines are now closed, they were famous for their usage of the Fell mountain railway system to aid braking for trains descending the Inclines (though this was not a full use of the Fell system like the North Island 's Rimutaka Incline ). Some of

1581-627: The air descends on the leeward side, it warms again (following the adiabatic lapse rate ) and is drier, having been stripped of much of its moisture. Often, a rain shadow will affect the leeward side of a range. As a consequence, large mountain ranges, such as the Andes, compartmentalize continents into distinct climate regions . Mountain ranges are constantly subjected to erosional forces which work to tear them down. The basins adjacent to an eroding mountain range are then filled with sediments that are buried and turned into sedimentary rock . Erosion

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1632-410: The botanist William Trownson), Mount Copernicus ( Nicolaus Copernicus ), Mount Galileo ( Galileo Galilei ) and Mount Davy ( Humphry Davy ; named by von Haast). Mountain range Mountain ranges are usually segmented by highlands or mountain passes and valleys . Individual mountains within the same mountain range do not necessarily have the same geologic structure or petrology . They may be

1683-487: The deeper crust, where temperatures and pressures are higher. By understanding the constitutive relationships between stress and strain in rocks, geologists can translate the observed patterns of rock deformation into a stress field during the geologic past. The following list of features are typically used to determine stress fields from deformational structures. For economic geology such as petroleum and mineral development, as well as research, modeling of structural geology

1734-1222: The dynamics of the stress field can be linked to important events in the geologic past; a common goal is to understand the structural evolution of a particular area with respect to regionally widespread patterns of rock deformation (e.g., mountain building , rifting ) due to plate tectonics . The study of geologic structures has been of prime importance in economic geology , both petroleum geology and mining geology . Folded and faulted rock strata commonly form traps that accumulate and concentrate fluids such as petroleum and natural gas . Similarly, faulted and structurally complex areas are notable as permeable zones for hydrothermal fluids, resulting in concentrated areas of base and precious metal ore deposits. Veins of minerals containing various metals commonly occupy faults and fractures in structurally complex areas. These structurally fractured and faulted zones often occur in association with intrusive igneous rocks . They often also occur around geologic reef complexes and collapse features such as ancient sinkholes . Deposits of gold , silver , copper , lead , zinc , and other metals, are commonly located in structurally complex areas. Structural geology

1785-485: The east. This mass of rock was removed as the range was actively undergoing uplift. The removal of such a mass from the core of the range most likely caused further uplift as the region adjusted isostatically in response to the removed weight. Rivers are traditionally believed to be the principal cause of mountain range erosion, by cutting into bedrock and transporting sediment. Computer simulation has shown that as mountain belts change from tectonically active to inactive,

1836-467: The formation of structure of rock under the earth are the stress and strain fields. Stress is a pressure, defined as a directional force over area. When a rock is subjected to stresses, it changes shape. When the stress is released, the rock may or may not return to its original shape. That change in shape is quantified by strain, the change in length over the original length of the material in one dimension. Stress induces strain which ultimately results in

1887-580: The intersection lineation of a S 1 cleavage and bedding is the L 1-0 intersection lineation (also known as the cleavage-bedding lineation). Stretching lineations may be difficult to quantify, especially in highly stretched ductile rocks where minimal foliation information is preserved. Where possible, when correlated with deformations (as few are formed in folds, and many are not strictly associated with planar foliations), they may be identified similar to planar surfaces and folds, e.g.; L 1 , L 2 . For convenience some geologists prefer to annotate them with

1938-401: The letter D denoting a deformation event. For example, D 1 , D 2 , D 3 . Folds and foliations, because they are formed by deformation events, should correlate with these events. For example, an F 2 fold, with an S 2 axial plane foliation would be the result of a D 2 deformation. Metamorphic events may span multiple deformations. Sometimes it is useful to identify them similarly to

1989-631: The nature of rocks imaged to be in the deep crust. Rock microstructure or texture of rocks is studied by structural geologists on a small scale to provide detailed information mainly about metamorphic rocks and some features of sedimentary rocks , most often if they have been folded. Textural study involves measurement and characterisation of foliations , crenulations , metamorphic minerals, and timing relationships between these structural features and mineralogical features. Usually this involves collection of hand specimens, which may be cut to provide petrographic thin sections which are analysed under

2040-478: The oil, gas and mineral exploration industries as structures such as faults, folds and unconformities are primary controls on ore mineralisation and oil traps. Modern regional structure is being investigated using seismic tomography and seismic reflection in three dimensions, providing unrivaled images of the Earth's interior, its faults and the deep crust. Further information from geophysics such as gravity and airborne magnetics can provide information on

2091-448: The orientation, deformation and relationships of stratigraphy (bedding), which may have been faulted, folded or given a foliation by some tectonic event. This is mainly a geometric science, from which cross sections and three-dimensional block models of rocks, regions, terranes and parts of the Earth's crust can be generated. Study of regional structure is important in understanding orogeny , plate tectonics and more specifically in

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2142-414: The periodic array of atoms that make up a crystal lattice. Dislocations are present in all real crystallographic materials. Hardness is difficult to quantify. It is a measure of resistance to deformation, specifically permanent deformation. There is precedent for hardness as a surface quality, a measure of the abrasiveness or surface-scratching resistance of a material. If the material being tested, however,

2193-406: The planar surface, with the flat edge horizontal and measuring the angle of the lineation clockwise from horizontal. The orientation of the lineation can then be calculated from the rake and strike-dip information of the plane it was measured from, using a stereographic projection . If a fault has lineations formed by movement on the plane, e.g.; slickensides , this is recorded as a lineation, with

2244-602: The range is protected as the Paparoa National Park , which was established in 1987. Within this park, the 1995 Cave Creek disaster occurred. Two Grey Valley residents, Trevor Johnston and Kevin Dash, became the first people to traverse the length of the Paparoa Ranges from north to south in mid-1986. They later wrote a book about the experience, Touch the Wilderness. Numerous species of flora and fauna are found in

2295-619: The ranges of the Himalayas , Karakoram , Hindu Kush , Alborz , Caucasus , and the Alps . The Himalayas contain the highest mountains in the world, including Mount Everest , which is 8,848 metres (29,029 ft) high. Mountain ranges outside these two systems include the Arctic Cordillera , Appalachians , Great Dividing Range , East Siberians , Altais , Scandinavians , Qinling , Western Ghats , Vindhyas , Byrrangas , and

2346-627: The rate of erosion drops because there are fewer abrasive particles in the water and fewer landslides. Mountains on other planets and natural satellites of the Solar System, including the Moon , are often isolated and formed mainly by processes such as impacts, though there are examples of mountain ranges (or "Montes") somewhat similar to those on Earth. Saturn 's moon Titan and Pluto , in particular, exhibit large mountain ranges in chains composed mainly of ices rather than rock. Examples include

2397-428: The rock went through to get to that final structure. Knowing the conditions of deformation that lead to such structures can illuminate the history of the deformation of the rock. Temperature and pressure play a huge role in the deformation of rock. At the conditions under the earth's crust of extreme high temperature and pressure, rocks are ductile . They can bend, fold or break. Other vital conditions that contribute to

2448-402: The structural and tectonic history of the area. The mechanical properties of rock play a vital role in the structures that form during deformation deep below the earth's crust. The conditions in which a rock is present will result in different structures that geologists observe above ground in the field. The field of structural geology tries to relate the formations that humans see to the changes

2499-465: The structural features for which they are responsible, e.g.; M 2 . This may be possible by observing porphyroblast formation in cleavages of known deformation age, by identifying metamorphic mineral assemblages created by different events, or via geochronology . Intersection lineations in rocks, as they are the product of the intersection of two planar structures, are named according to the two planar structures from which they are formed. For instance,

2550-534: The trace of a planar feature on another planar surface). The inclination of a planar structure in geology is measured by strike and dip . The strike is the line of intersection between the planar feature and a horizontal plane, taken according to the right hand convention, and the dip is the magnitude of the inclination, below horizontal, at right angles to strike. For example; striking 25 degrees East of North, dipping 45 degrees Southeast, recorded as N25E,45SE. Alternatively, dip and dip direction may be used as this

2601-520: Was the first (known) European to come to New Zealand ( Aotearoa ), which he named Staten Landt , and he first encountered it on 13 December 1642. Tasman had 110 men under his command and was travelling with two ships, the Heemskerck and the Zeehaen . It is believed that the ships were off Punakaiki and if so, it was the Paparoa Range that they saw. Significant coal deposits have been found in

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