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Mudcrack
Mudcracks (also known as mud cracks, desiccation cracks or cracked mud) are sedimentary structures formed as muddy sediment dries and contracts.Jackson, J.A., 1997, ''Glossary of Geology'' (4th ed.), American Geological Institute, Alexandria, VA, 769 p.Stow, D.A., 2005, ''Sedimentary Rocks in the Field'', Academic Press, London, 320 p. Crack formation also occurs in clay-bearing soils as a result of a reduction in water content. Formation of mudcrack Naturally forming mudcracks start as wet, muddy sediment dries up and contracts. A strain is developed because the top layer shrinks while the material below stays the same size. When this strain becomes large enough, channel cracks form in the dried-up surface to relieve the strain. Individual cracks spread and join up, forming a polygonal, interconnected network of forms called "tesselations." If the strain continues to build, the polygons start to curl upwards. This characteristic can be used in geology to understand the origi ...
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Syneresis Cracks
Syneresis cracks (also known as subaqueous shrinkage cracks) are a sedimentary structures, sedimentary structure developed by the shrinkage of sediment without desiccation – not to be confused with mudcracks, desiccation cracks. Syneresis (chemistry), Syneresis is the expulsion of a liquid from a gel-like substance. Syneresis cracks are formed by the contraction of clay in response to changes in the salinity of a liquid surrounding a deposit. The cracks can occur, for example, in mudstones deposited between two beds of sandstone. The markings would have been formed subaqueous soil, subaqueously on the bedding surface and could resemble desiccation mudcracks, but are not continuous and vary in shape. They commonly occur in thin mudstones interbedded with sandstones, as positive relief on the bottom of the sandstone, or as negative relief on the top of the mudstone. Subaqueous shrinkage cracks can develop on and through a surface that has been continuously covered in water. Syner ...
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Syneresis Crack
Syneresis cracks (also known as subaqueous shrinkage cracks) are a sedimentary structure developed by the shrinkage of sediment without desiccation – not to be confused with desiccation cracks. Syneresis is the expulsion of a liquid from a gel-like substance. Syneresis cracks are formed by the contraction of clay in response to changes in the salinity of a liquid surrounding a deposit. The cracks can occur, for example, in mudstones deposited between two beds of sandstone. The markings would have been formed subaqueously on the bedding surface and could resemble desiccation mudcracks, but are not continuous and vary in shape. They commonly occur in thin mudstones interbedded with sandstones, as positive relief on the bottom of the sandstone, or as negative relief on the top of the mudstone. Subaqueous shrinkage cracks can develop on and through a surface that has been continuously covered in water. Syneresis cracks in some shales and lime mudstones may initially be preserved ...
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Mud Cracks On Mars
In January 2017, scientists announced the possible discovery of mud cracks in Gale Crater on Mars. The Curiosity Rover imaged what may be the first mud cracks (desiccation cracks) ever found on Mars. They may have been formed from drying mud. The site, called “Old Soaker,” was within an exposure of Murray formation mudstone on lower Mount Sharp. It is hypothesized that these cracks formed more than 3 billion years ago and then were buried by more sediment. All this material eventually turned into rock. Later wind erosion removed the layers that covered the cracked layer. The cracks were filled with material which was resistant to later erosion. This erosion resistant material formed raised ridges, as some of the surrounding layer was removed. This is the first sighting of mud cracks. Previously, Curiosity has examined cracks and ridges of different shapes that were made by groundwater carrying minerals, such as calcium sulfate. Cracks for this process were caused by the press ...
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Tessellation
A tessellation or tiling is the covering of a surface, often a plane, using one or more geometric shapes, called ''tiles'', with no overlaps and no gaps. In mathematics, tessellation can be generalized to higher dimensions and a variety of geometries. A periodic tiling has a repeating pattern. Some special kinds include '' regular tilings'' with regular polygonal tiles all of the same shape, and '' semiregular tilings'' with regular tiles of more than one shape and with every corner identically arranged. The patterns formed by periodic tilings can be categorized into 17 wallpaper groups. A tiling that lacks a repeating pattern is called "non-periodic". An '' aperiodic tiling'' uses a small set of tile shapes that cannot form a repeating pattern (an aperiodic set of prototiles). A '' tessellation of space'', also known as a space filling or honeycomb, can be defined in the geometry of higher dimensions. A real physical tessellation is a tiling made of materials such as ...
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Polygonal Patterned Ground
Polygonal, patterned ground is quite common in some regions of Mars. It is commonly believed to be caused by the sublimation of ice from the ground. Sublimation is the direct change of solid ice to a gas. This is similar to what happens to dry ice on the Earth. Places on Mars that display polygonal ground may indicate where future colonists can find water ice. Low center polygons have been proposed as a marker for ground ice. Polygonal terrain is also found on earth's permafrost. Patterned ground forms in a mantle layer, called latitude dependent mantle, that fell from the sky when the climate was different. On Mars, researches have found patterned ground that formed from fractures and patterned ground formed by the arrangement of boulders. It is not yet clear what caused boulders to form patterns, but it does not seem that fractures caused the boulders to move around. Esp 037167 1445mantle.jpg, Surface showing appearance with and without mantle covering, as seen by HiRIS ...
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Columnar Jointing
Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as Joint (geology), joints, result in the formation of a regular array of polygonal Prism (geometry), prisms, or columns. Columnar jointing occurs in many types of igneous rocks (e.g. basalt, andesite, rhyolite), and forms as the rock cools and contracts. Columnar jointing can occur in cooling lava flows and ashflow tuffs (ignimbrites), as well as in some shallow intrusions. Columnar jointing also occurs rarely in sedimentary rocks, due to a combination of Solution_(chemistry), dissolution and Precipitation_(chemistry), reprecipitation of interstitial minerals (often quartz or cryptocrystalline silica) by hot, hydrothermal fluids and the expansion and contraction of the rock unit, both resulting from the presence of a nearby Igneous intrusion, magmatic intrusion. The columns can vary from 3 meters to a few centimeters in diameter, and can be as much as 30 meters tall. The ...
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Sedimentary Structures
Sedimentary structures include all kinds of features in sediments and sedimentary rocks, formed at the time of deposition. Sediments and sedimentary rocks are characterized by bedding, which occurs when layers of sediment, with different particle sizes are deposited on top of each other. These beds range from millimeters to centimeters thick and can even go to meters or multiple meters thick. Sedimentary structures such as cross-bedding, graded bedding, and ripple marks are utilized in stratigraphic studies. They help indicate the original position of strata in geologically complex terrains. They also provide insight into the depositional environment of the sediment. Flow structures There are two kinds of flow structures: bidirectional (multiple directions, back-and-forth) and unidirectional. Flow regimes in single-direction (typically fluvial) flow, which at varying speeds and velocities produce different structures, are called bedforms. In the ''lower flow regime'', ...
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Polygonal Patterned Ground
Polygonal, patterned ground is quite common in some regions of Mars. It is commonly believed to be caused by the sublimation of ice from the ground. Sublimation is the direct change of solid ice to a gas. This is similar to what happens to dry ice on the Earth. Places on Mars that display polygonal ground may indicate where future colonists can find water ice. Low center polygons have been proposed as a marker for ground ice. Polygonal terrain is also found on earth's permafrost. Patterned ground forms in a mantle layer, called latitude dependent mantle, that fell from the sky when the climate was different. On Mars, researches have found patterned ground that formed from fractures and patterned ground formed by the arrangement of boulders. It is not yet clear what caused boulders to form patterns, but it does not seem that fractures caused the boulders to move around. Esp 037167 1445mantle.jpg, Surface showing appearance with and without mantle covering, as seen by HiRIS ...
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Fold (geology)
In structural geology, a fold is a stack of originally planar surfaces, such as sedimentary rock, sedimentary stratum, strata, that are bent or curved (''"folded"'') during permanent deformation (engineering), deformation. Folds in rocks vary in size from microscopic crinkles to mountain-sized folds. They occur as single isolated folds or in periodic sets (known as ''fold trains''). wikt:synsedimentary, Synsedimentary folds are those formed during sedimentary deposition. Folds form under varied conditions of stress (physics), stress, pore pressure, and temperature gradient, as evidenced by their presence in soft sedimentary rock, sediments, the full spectrum of metamorphic rocks, and even as primary flow structures in some igneous rocks. A set of folds distributed on a regional scale constitutes a fold belt, a common feature of orogeny, orogenic zones. Folds are commonly formed by shortening of existing layers, but may also be formed as a result of displacement on a non-planar f ...
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Craquelure
Craquelure (; ) is a fine pattern of dense cracking formed on the surface of materials. It can be a result of drying, shock, aging, intentional patterning, or a combination of all four. The term is most often used to refer to tempera or oil paintings, but it can also develop in old ivory carvings or painted miniatures on an ivory backing. Recently, analysis of craquelure has been proposed as a way to authenticate art. In ceramics, craquelure in ceramic glazes, where it is often a desired effect, is called "crackle"; it is a characteristic of Chinese Ge ware in particular. This is usually differentiated from crazing, which is a glaze defect in firing, or the result of aging or damage. In painted surfaces Painting systems are composed of complex layers with unique mechanical properties that depend on the type of drying oil or paint medium used and the presence of paint additives, such as organic solvents, surfactants, and plasticizers. Understanding the mechanism of craquelure f ...
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Fault Mechanics
Fault mechanics is a field of study that investigates the behavior of geologic faults. Behind every good earthquake is some weak rock. Whether the rock remains weak becomes an important point in determining the potential for bigger earthquakes. On a small scale, fractured rock behaves essentially the same throughout the world, in that the angle of friction is more or less uniform (see Fault friction). A small element of rock in a larger mass responds to stress changes in a well defined manner: if it is squeezed by differential stresses greater than its strength, it is capable of large deformations. A band of weak, fractured rock in a competent mass can deform to resemble a classic geologic fault. Using seismometers and earthquake location, the requisite pattern of micro-earthquakes can be observed. For earthquakes, it all starts with an embedded penny-shaped crack as first envisioned by Brune. As illustrated, an earthquake zone may start as a single crack, growing to ...
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Erosion
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, transports it to another location where it is deposit (geology), deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by Solvation, dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and Wind wave, waves; glacier, glacial Plucking (glaciation), plucking, Abrasion (geology), abrasion, and scour; areal flooding; Aeolian processes, wind abrasion; groundwater processes; and Mass wastin ...
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