query: 4 examples of sediment that might become sedimentary rock

pos: Sedimentary rock are composed of other rock fragments that were cemented by silicate minerals. Clastic rocks are composed largely of quartz, feldspar, rock (lithic) fragments, clay minerals, and mica; any type of mineral may be present, but they in general represent the minerals that exist locally. 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 (>2 mm diameter), sand (1/16 to 2 mm diameter), and mud (clay is <1/256 mm and silt is between 1/16 and 1/256 mm). The classification of clastic sedimentary rocks

pos: Sedimentary rock by feldspar, micas, and finally other less stable minerals that are only present when little weathering has occurred. The amount of weathering depends mainly on the distance to the source area, the local climate and the time it took for the sediment to be transported to the point where it is deposited. In most sedimentary rocks, mica, feldspar and less stable minerals have been reduced to clay minerals like kaolinite, illite or smectite. Among the three major types of rock, fossils are most commonly found in sedimentary rock. Unlike most igneous and metamorphic rocks, sedimentary rocks form at temperatures and

pos: Geology of solar terrestrial planets is basalt, a denser volcanic rock that is the primary constituent of the ocean floors. Sedimentary rock is formed from the accumulation of sediment that becomes compacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form only about 5% of the crust. The third form of rock material found on Earth is metamorphic rock, which is created from the transformation of pre-existing rock types through high pressures, high temperatures, or both. The most abundant silicate minerals on the Earth's surface include quartz, the feldspars, amphibole, mica, pyroxene, and olivine. Common carbonate minerals include calcite

pos: Mudstone Mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Grain size is up to with individual grains too small to be distinguished without a microscope. With increased pressure over time, the platy clay minerals may become aligned, with the appearance of fissility or parallel layering. This finely bedded material that splits readily into thin layers is called "shale", as distinct from "mudstone". The lack of fissility or layering in mudstone may be due to either original texture or the disruption of layering by burrowing organisms in the sediment prior to lithification.

pos: Quartz arenite sandstone" can also be used for a quartz arenite. Quartz arenites are the most mature sedimentary rocks possible, and are often referred to as ultra- or super-mature, and are usually cemented by silica. They often exhibit both textural and compositional maturity. The two primary sedimentary depositional environments that produce quartz arenites are beaches/upper shoreface and aeolian processes, due to their high residence time, high transport distance, and/or high energy of the environment. Most of the time, these sediments are reworked over and over, even being eroded out of a lithified rock and becoming a brand new sediment and rock. This

neg: Sedimentary rock of the tide. They are often cross-cut by gullies, where the current is strong and the grain size of the deposited sediment is larger. Where rivers enter the body of water, either on a sea or lake coast, deltas can form. These are large accumulations of sediment transported from the continent to places in front of the mouth of the river. Deltas are dominantly composed of clastic sediment (in contrast to chemical). A sedimentary rock formed on land has a continental sedimentary environment. Examples of continental environments are lagoons, lakes, swamps, floodplains and alluvial fans. In the quiet water of

neg: Sedimentary rock the sedimentary cover can become unstable, causing turbidity currents. Turbidity currents are sudden disturbances of the normally quite deep marine environment and can cause the geologically speaking instantaneous deposition of large amounts of sediment, such as sand and silt. The rock sequence formed by a turbidity current is called a turbidite. The coast is an environment dominated by wave action. At a beach, dominantly denser sediment such as sand or gravel, often mingled with shell fragments, is deposited, while the silt and clay sized material is kept in mechanical suspension. Tidal flats and shoals are places that sometimes dry because

neg: Sedimentary rock a sediment can leave more traces than just fossils. Preserved tracks and burrows are examples of trace fossils (also called ichnofossils). Such traces are relatively rare. Most trace fossils are burrows of molluscs or arthropods. This burrowing is called bioturbation by sedimentologists. It can be a valuable indicator of the biological and ecological environment that existed after the sediment was deposited. On the other hand, the burrowing activity of organisms can destroy other (primary) structures in the sediment, making a reconstruction more difficult. Secondary structures can also form by diagenesis or the formation of a soil (pedogenesis) when a sediment

neg: Sedimentary basin analysis Sedimentary basin analysis Sedimentary basin analysis is a geologic method by which the history of a sedimentary basin is revealed, by analyzing the sediment fill itself. Aspects of the sediment, namely its composition, primary structures, and internal architecture, can be synthesized into a history of the basin fill. Such a synthesis can reveal how the basin formed, how the sediment fill was transported or precipitated, and reveal sources of the sediment fill. From such syntheses models can be developed to explain broad basin formation mechanisms. Examples of such basinal environments include backarc, forearc, passive margin, epicontinental, and extensional basins. Sedimentary

neg: Sedimentary rock groups based on their mineralogy: Sedimentary rocks are formed when sediment is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension. This sediment is often formed when weathering and erosion break down a rock into loose material in a source area. The material is then transported from the source area to the deposition area. The type of sediment transported depends on the geology of the hinterland (the source area of the sediment). However, some sedimentary rocks, such as evaporites, are composed of material that form at the place of deposition. The nature of a

neg: Sedimentary rock sedimentary rock, therefore, not only depends on the sediment supply, but also on the sedimentary depositional environment in which it formed. The term diagenesis is used to describe all the chemical, physical, and biological changes, exclusive of surface weathering, undergone by a sediment after its initial deposition. Some of those processes cause the sediment to consolidate into a compact, solid substance from the originally loose material. Young sedimentary rocks, especially those of Quaternary age (the most recent period of the geologic time scale) are often still unconsolidated. As sediment deposition builds up, the overburden (lithostatic) pressure rises, and a process

neg: Sediment Sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation and if buried, may eventually become sandstone and siltstone (sedimentary rocks). Sediments are most often transported by water (fluvial processes), but also wind (aeolian processes) and glaciers. Beach sands and river channel deposits are examples of fluvial transport and

neg: Sedimentary rock difficult to distinguish from folds and faults formed by tectonic forces acting on lithified rocks. The setting in which a sedimentary rock forms is called the sedimentary environment. Every environment has a characteristic combination of geologic processes and circumstances. The type of sediment that is deposited is not only dependent on the sediment that is transported to a place, but also on the environment itself. A marine environment means that the rock was formed in a sea or ocean. Often, a distinction is made between deep and shallow marine environments. Deep marine usually refers to environments more than 200 m

neg: Depositional environment ancient sediments are recognised using a combination of sedimentary facies, facies associations, sedimentary structures and fossils, particularly trace fossil assemblages, as they indicate the environment in which they lived. Depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record. In most cases the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the

neg: Rock microstructure deformation events and orientation information. Structures occur on hand-specimen scale and above. Microstructure analysis describes the textural features of the rock, and can provide information on the conditions of formation, petrogenesis, and subsequent deformation, folding or alteration events. Description of sedimentary rock microstructure aims to provide information on the conditions of deposition of the sediment, the paleo-environment, and the provenance of the sedimentary material. Methods involve description of clast size, sorting, composition, rounding or angularity, sphericity and description of the matrix. Sedimentary microstructures, specifically, may include microscopic analogs of larger sedimentary structural features such as cross-bedding, syn-sedimentary faults, sediment slumping,

neg: Sedimentary structures depositional environment and paleocurrent directions. They are formed when the sediment is deposited. Secondary sedimentary structures form after primary deposition occurs or, in some cases, during the diagenesis of a sedimentary rock. Common secondary structures include any form of bioturbation, soft-sediment deformation, teepee structures, root-traces, and soil mottling. Liesegang rings, cone-in-cone structures, raindrop impressions, and vegetation-induced sedimentary structures would also be considered secondary structures. Sedimentary structures Sedimentary structures include all kinds of features 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

neg: Facies foundations of modern stratigraphy, which replaced the earlier notions of Neptunism. Ideally, a sedimentary facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment. Sedimentary facies are either descriptive or interpretative. Sedimentary facies are bodies of sediment that are recognizably distinct from adjacent sediments that resulted from different depositional environments. Generally, geologists distinguish facies by the aspect of the rock or sediment being studied. Facies based on petrological characters (such as grain size and mineralogy) are called lithofacies, whereas facies based on fossil content are called "biofacies". A facies is usually

neg: Sedimentary structures which dip upstream at an angle of about ten degrees that can be up to five meters in length. They can be identified by their low angle foresets. For the most part, antidunes bedforms are destroyed during decreased flow, and therefore cross bedding formed by antidunes will not be preserved. A number of biologically-created sedimentary structures exist, called trace fossils. Examples include burrows and various expressions of bioturbation. Ichnofacies are groups of trace fossils that together help give information on the depositional environment. In general, as deeper (into the sediment) burrows become more common, the shallower the water. As (intricate)

neg: Sedimentary rock between successive layers indicate changes to the environment over time. Sedimentary rocks can contain fossils because, unlike most igneous and metamorphic rocks, they form at temperatures and pressures that do not destroy fossil remains. Sedimentary rock Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of

neg: Facies further subdivided, for example, one might refer to a "tan, cross-bedded oolitic limestone facies" or a "shale facies". The characteristics of the rock unit come from the depositional environment and from the original composition. Sedimentary facies reflect their depositional environment, each facies being a distinct kind of sediment for that area or environment. Since its inception in 1838, the facies concept has been extended to related geological concepts. For example, characteristic associations of organic microfossils, and particulate organic material, in rocks or sediments, are called palynofacies. Discrete seismic units are similarly referred to as seismic facies. Sedimentary facies are described

neg: Clastic rock particular chemical and trace element signatures, especially osmiridium. Clastic rock Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Geologists use the term clastic with reference to sedimentary rocks as well as to particles in sediment transport whether in suspension or as bed load, and in sediment deposits. Clastic sedimentary rocks are rocks composed predominantly of broken pieces or "clasts" of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on

neg: Clastic rock Clastic rock Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Geologists use the term clastic with reference to sedimentary rocks as well as to particles in sediment transport whether in suspension or as bed load, and in sediment deposits. Clastic sedimentary rocks are rocks composed predominantly of broken pieces or "clasts" of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on grain size, clast and cementing material (matrix) composition,

neg: Sedimentary structures surface traces become more common, the water becomes deeper. Microbes may also interact with sediment to form Microbially Induced Sedimentary Structures. Soft-sediment deformation structures or SSD, is a consequence of the loading of wet sediment as burial continues after deposition. The heavier sediment "squeezes" the water out of the underlying sediment due to its own weight. There are three common variants of SSD: Bedding Plane Structures are commonly used as paleocurrent indicators. They are formed when sediment has been deposited and then reworked and reshaped. They include: These structures are within sedimentary bedding and can help with the interpretation of

neg: Sedimentary rock Sedimentary rock Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). Before being deposited, the geological detritus was formed by weathering and erosion from the source area, and then transported to the place of deposition by water,

neg: Sedimentary rock and sedimentation. The rate at which sediment is deposited differs depending on the location. A channel in a tidal flat can see the deposition of a few metres of sediment in one day, while on the deep ocean floor each year only a few millimetres of sediment accumulate. A distinction can be made between normal sedimentation and sedimentation caused by catastrophic processes. The latter category includes all kinds of sudden exceptional processes like mass movements, rock slides or flooding. Catastrophic processes can see the sudden deposition of a large amount of sediment at once. In some sedimentary environments, most of

neg: Sedimentary rock (regardless of grain size) although some older literature uses the term "shale" as a synonym for mudrock. Biochemical sedimentary rocks are created when organisms use materials dissolved in air or water to build their tissue. Examples include: Chemical sedimentary rock forms when mineral constituents in solution become supersaturated and inorganically precipitate. Common chemical sedimentary rocks include oolitic limestone and rocks composed of evaporite minerals, such as halite (rock salt), sylvite, barite and gypsum. This fourth miscellaneous category includes rocks formed by Pyroclastic flows, impact breccias, volcanic breccias, and other relatively uncommon processes. Alternatively, sedimentary rocks can be subdivided into compositional

neg: Sedimentary rock removes most deposited sediment shortly after deposition. That new rock layers are above older rock layers is stated in the principle of superposition. There are usually some gaps in the sequence called unconformities. These represent periods where no new sediments were laid down, or when earlier sedimentary layers were raised above sea level and eroded away. Sedimentary rocks contain important information about the history of the Earth. They contain fossils, the preserved remains of ancient plants and animals. Coal is considered a type of sedimentary rock. The composition of sediments provides us with clues as to the original rock. Differences

neg: Unconformity distinct separation plane or contact, sometimes consisting of soils, paleosols, or beds of pebbles derived from the underlying rock. Unconformity 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. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787

neg: Sedimentary rock up where tectonics have tilted or overturned sedimentary layers. Sedimentary rocks are laid down in layers called beds or strata. A bed is defined as a layer of rock that has a uniform lithology and texture. Beds form by the deposition of layers of sediment on top of each other. The sequence of beds that characterizes sedimentary rocks is called bedding. Single beds can be a couple of centimetres to several meters thick. Finer, less pronounced layers are called laminae, and the structure a lamina forms in a rock is called lamination. Laminae are usually less than a few centimetres

neg: Lamination (geology) Lamination (geology) In geology, lamination is a small-scale sequence of fine layers ("laminae"; singular: "lamina") that occurs in sedimentary rocks. Laminae are normally smaller and less pronounced than bedding. Lamination is often regarded as planar structures one centimetre or less in thickness, whereas bedding layers are greater than one centimetre. However, structures from several millimetres to many centimetres have been described as laminae. A single sedimentary rock can have both laminae and beds. Lamination consists of small differences in the type of sediment that occur throughout the rock. They are caused by cyclic changes in the supply of sediment. These

neg: Concretion Concretion A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin "con" meaning 'together' and "crescere" meaning 'to grow'. Concretions form within layers of sedimentary strata that have already been deposited. They usually form early in the burial history of the sediment, before the rest of the sediment is hardened into rock. This concretionary cement often makes the concretion harder

neg: Shallow water marine environment in grain size, with the smallest grains at the top. Also, Ripples, which are the smallest bedform type, and dunes, which are similar to ripples except are larger. Carbonaceous sedimentary rocks with several kinds of sedimentary structures within them can be found in shallow marine environments; they are a group of rocks that have a significant amount of non-skeletal matter along with siliciclastic or chemical constituents. Some examples include: Cross stratification is a layering structure found in gravel, sand, and coarse silt-sized sediment; the strata are distinct layers of sediment that are steeply inclined to the underlying surfaces of the

neg: Protolith Protolith A protolith is the original, unmetamorphosed rock from which a given metamorphic rock is formed ("proto-": first; "lithos": rock; both Greek). For example, the protolith of a slate is a shale or mudstone. Metamorphic rocks can be derived from any other kind of non-metamorphic rock and thus there is a wide variety of protoliths. Identifying a protolith is a major aim of metamorphic geology. Protoliths are non-metamorphic rocks and have no protoliths themselves. The non-metamorphic rocks fall into two classes: sedimentary rocks, formed from sediment, and igneous rocks, formed from magma. The source of the sediment of a sedimentary

neg: Jasperoid Jasperoid Jasperoid is a rare, peculiar type of metasomatic alteration and occurs in two main forms; sulfidic jasperoids and hematitic jasperoids. True jasperoids are different from jaspillite, which is a form of metamorphosed chemical sedimentary rock, and from jasper which is a chemical sediment. Sulfidic jasperoids are typical examples of silica-sulfide metasomatism of dolostones, and are found in Nevada and Iran. They are hard, dense purple-black rocks with considerable content of pyrite. The bodies in Nevada are quite thin (seldom greater than 8 m) and stratabound. Hematitic jasperoids are examples of advanced silica-hematite alteration, and are known only from the

neg: Geologic record Geologic record The geologic record in stratigraphy, paleontology and other natural sciences refers to the entirety of the layers of rock strata — deposits laid down by volcanism or by deposition of sediment derived from weathering detritus (clays, sands etc.) including all its fossil content and the information it yields about the history of the Earth: its past climate, geography, geology and the evolution of life on its surface. According to the law of superposition, sedimentary and volcanic rock layers are deposited on top of each other. They harden over time to become a solidified (competent) rock column, that may

neg: Beachrock sea level rise or deficit in sedimentary equilibrium. One way or another, unconsolidated sand that covers the beachrock draws away and the formation is revealed. If the process of cementation continues, new beachrock would be formed in a new position in the intertidal zone. Successive phases of sea level change may result in sequential zones of beachrock. Beachrock Beachrock is a friable to well-cemented sedimentary rock that consists of a variable mixture of gravel-, sand-, and silt-sized sediment that is cemented with carbonate minerals and has formed along a shoreline. Depending on location, the sediment that is cemented to form

neg: Unconformity Unconformity 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. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the

neg: Sedimentary budget a system. This sediment can come from any source with examples of sources and sinks consisting of: This sediment then enters the coastal system and is transported by longshore drift. A good example of the sediment budget and longshore drift working together in the coastal system is inlet ebb-tidal shoals, which store sand that has been transported by long shore transport. As well as storing sand these systems may also transfer or by pass sand into other beach systems, therefore inlet ebb-tidal shoal systems provide a good sources and sinks for the sediment budget. Wave swash and currents can impact

neg: Principle of lateral continuity Often, the sedimentary basin is within rocks that are very different from the sediments that are being deposited. In those cases, the lateral limits of the sedimentary layer will be marked by an abrupt change in rock type. Principle of lateral continuity The principle of lateral continuity states that layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous. As a result, rocks that are otherwise similar, but are now separated by a valley or other erosional feature, can be assumed to be originally continuous. Layers of sediment do not extend indefinitely; rather, the

neg: Depositional environment Depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record. In most cases the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the further back in geological time sediments were deposited, the more likely that direct modern analogues are not available (e.g. banded iron formations). Continental Transitional Marine Others Depositional environments in

neg: Detritus (geology) generation of sediment. Detritus (geology) Detritus (; adjective "detrital" ) is particles of rock derived from pre-existing rock through processes of weathering and erosion. A fragment of detritus is called a clast. Detrital particles can consist of lithic fragments (particles of recognisable rock), or of monomineralic fragments (mineral grains). These particles are often transported through sedimentary processes into depositional systems such as riverbeds, lakes or the ocean, forming sedimentary successions. Diagenetic processes can transform these sediments into rock through cementation and lithification, forming sedimentary rocks such as sandstone. These rocks can then in turn again be weathered and eroded to

neg: Sedimentary rock ripples. The longer flank of such ripples is on the upstream side of the current. Symmetric wave ripples occur in environments where currents reverse directions, such as tidal flats. Mudcracks are a bed form caused by the dehydration of sediment that occasionally comes above the water surface. Such structures are commonly found at tidal flats or point bars along rivers. Secondary sedimentary structures are those which formed after deposition. Such structures form by chemical, physical and biological processes within the sediment. They can be indicators of circumstances after deposition. Some can be used as way up criteria. Organic materials in

neg: Earth eruptions, flooding, weathering, glaciation, the growth of coral reefs, and meteorite impacts are among the processes that constantly reshape the Earth's surface over geological time. The continental crust consists of lower density material such as the igneous rocks granite and andesite. Less common is basalt, a denser volcanic rock that is the primary constituent of the ocean floors. Sedimentary rock is formed from the accumulation of sediment that becomes buried and compacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form about 5% of the crust. The third form of rock material found on

neg: Magnetofossil in the sedimentary record. The fossilization of the magnetite (magnetofossils) within sediments contributes largely to the natural remanent magnetization of the sediment layers. The natural remanent magnetization is the permanent magnetism remaining in a rock or sediment after it has formed. Magnetotactic bacteria use iron to create magnetite in magnetosomes. As a result of this process, increased iron levels correlate with increased production of magnetotactic bacteria. Increases in iron levels have been long associated with hyperthermal (period of warming, usually between 4-8 degrees Celsius) periods in the Earth's history. These hyperthermal events, such as the Palaeocene-Eocene Thermal Maximum or the

neg: Clastic dike Clastic dike 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 (mobilization of pressurized pore fluids) or passively by water, wind, and gravity (sediment swept into open cracks). Diagenesis may play a role in the formation of some dikes. Clastic dikes are commonly 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

neg: Sedimentary rock Frost weathering can form cracks in the soil that fill with rubble from above. Such structures can be used as climate indicators as well as way up structures. Density contrasts can also cause small-scale faulting, even while sedimentation progresses (synchronous-sedimentary faulting). Such faulting can also occur when large masses of non-lithified sediment are deposited on a slope, such as at the front side of a delta or the continental slope. Instabilities in such sediments can result in the deposited material to slump, producing fissures and folding. The resulting structures in the rock are syn-sedimentary folds and faults, which can be

neg: Sedimentary rock down, and the deposited sediment is normally a fine dark clay. Dark rocks, rich in organic material, are therefore often shales. The size, form and orientation of clasts (the original pieces of rock) in a sediment is called its texture. The texture is a small-scale property of a rock, but determines many of its large-scale properties, such as the density, porosity or permeability. The 3D orientation of the clasts is called the fabric of the rock. Between the clasts, the rock can be composed of a matrix (a cement) that consists of crystals of one or more precipitated minerals. The

neg: Sediment body of water that were, upon death, covered by accumulating sediment. Lake bed sediments that have not solidified into rock can be used to determine past climatic conditions. The major areas for deposition of sediments in the marine environment include: One other depositional environment which is a mixture of fluvial and marine is the turbidite system, which is a major source of sediment to the deep sedimentary and abyssal basins as well as the deep oceanic trenches. Any depression in a marine environment where sediments accumulate over time is known as a sediment trap. The null point theory explains how

neg: Sedimentary rock below the water surface. Shallow marine environments exist adjacent to coastlines and can extend to the boundaries of the continental shelf. The water movements in such environments have a generally higher energy than that in deep environments, as wave activity diminishes with depth. This means that coarser sediment particles can be transported and the deposited sediment can be coarser than in deeper environments. When the sediment is transported from the continent, an alternation of sand, clay and silt is deposited. When the continent is far away, the amount of such sediment deposited may be small, and biochemical processes dominate the

neg: Salt Point State Park making parts of the sandstone harden while other parts soften. The layers of sedimentary rock show evidence of a deep-sea fan. A deep-sea fan is caused when there is dense, turbulent sediment filled water flowing down a submarine canyon. This highly dense water is called a turbidity current. Something that may cause a turbidity current are earthquakes or storms that create a submarine slide. When this sediment filled water leaves the end of the canyon it spreads out in a fan like shape. The sediment is thinner and thinner the farther away the sediment is from the submarine canyon. All

neg: Sedimentary budget Sedimentary budget Sedimentary budgets are a coastal management tool used to analyze and describe the different sediment inputs (sources) and outputs (sinks) on the coasts, which is used to predict morphological change in any particular coastline over time. Within a coastal environment the rate of change of sediment is dependent on the amount of sediment brought into the system versus the amount of sediment that leaves the system. These inputs and outputs of sediment then equate to the total balance of the system and more than often reflect the amounts of erosion or accretion affecting the morphology of the coast.

neg: Sedimentary rock to such places. Typically sediments depositing on the ocean floor are fine clay or small skeletons of micro-organisms. At 4 km depth, the solubility of carbonates increases dramatically (the depth zone where this happens is called the lysocline). Calcareous sediment that sinks below the lysocline dissolves; as a result, no limestone can be formed below this depth. Skeletons of micro-organisms formed of silica (such as radiolarians) are not as soluble and still deposit. An example of a rock formed of silica skeletons is radiolarite. When the bottom of the sea has a small inclination, for example at the continental slopes,

neg: Beachrock Beachrock Beachrock is a friable to well-cemented sedimentary rock that consists of a variable mixture of gravel-, sand-, and silt-sized sediment that is cemented with carbonate minerals and has formed along a shoreline. Depending on location, the sediment that is cemented to form beachrock can consist of a variable mixture of shells, coral fragments, rock fragments of different types, and other materials. It can contain scattered artifacts, pieces of wood, and coconuts. Beachrock typically forms within the intertidal zone within tropical or semitropical regions. However, Quaternary beachrock is also found as far north and south as 60° latitude. Beachrock units

neg: Compression fossil Compression fossil A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression fossils, it is very common to find plants preserved this way. The reason for this is that physical compression of the rock often leads to distortion of the fossil. The best fossils of leaves are found preserved in fine layers of sediment that have been compressed in a direction perpendicular to the plane of the deposited sediment. Since leaves are basically flat, the resulting distortion is minimal. Plant stems and other three-dimensional

neg: Nahanni National Park Reserve same action also caused volcanic activity, sending molten lava into but not through the sedimentary rock. While there are no volcanoes in the park, towers of heated rock called igneous batholiths were sent upwards, pushing the sediment further up. The top layer of sedimentary rock was eventually eroded away, resulting in granite towers that form the Ragged Range. Over the last 2 million years, glaciers have covered most of North America, creating most of the land formations seen today. While previous ice ages affected the park area, the most recent, the Wisconsin Ice Age (85,000-10,000 years ago) touched only the

neg: Chauncey Peak in the process that would ultimately create the Atlantic Ocean. In the area that is now the Metacomet Ridge and surrounding sedimentary rock basin, massive basalt (traprock) lava flows spread across the prehistoric rift valley, some of them several hundred feet thick, over a period of 20 million years. Sediment accumulated between lava flows and lithified into sedimentary rock. After the rifting processes ceased, layers of strata faulted and tilted upward. Subsequent erosion, glaciation, and uplift exposed the weather resistant edge of the traprock lava sheets, creating the cliffline of the Metacomet Ridge as it is today. The mineral content

neg: Mount Magazine Ozark National Forest despite it being much closer to the Ouachita National Forest. As the South American plate collided with the North American plate during the late Paleozoic, a major foreland basin, the Arkoma Basin, developed north of the Ouachita Mountains. Small grains of sediment that had filled the Arkoma Basin were compacted and cemented into sedimentary rock. As the land rose above sea level, small streams developed that eventually merged into the Arkansas River. After millions of years of erosion, synclines like Mount Magazine have become the most positive topographic features; this phenomenon is the result of the rapid

neg: Hemipelagic sediment sediment directly depends on the composition of the adjacent land mass and geologic events such as volcanism that influence sediment input into the ocean. Hemipelagic sediments are mainly terrigenous but can also have biological oozes from marine organisms like Radiolarians or Diatoms. Radiolarians are a species of zooplankton that produce silica tests, or shells and Diatoms are photosynthetic organisms that live in the sunlit region of the ocean. Both organisms are visible in the sedimentary rock record. For example, in the Galice Formation in Oregon the hemipelagic sequence was composed of slaty radiolarian argillite with radiolarian chert present as well.

neg: Jasperoid sequences in Iran, Iraq and Turkey. Hematitic jasperoid is only found within the Glengarry basin, Western Australia, although it probably represents an end-member state of a variety of alteration and metasomatism styles found elsewhere. Jasperoid Jasperoid is a rare, peculiar type of metasomatic alteration and occurs in two main forms; sulfidic jasperoids and hematitic jasperoids. True jasperoids are different from jaspillite, which is a form of metamorphosed chemical sedimentary rock, and from jasper which is a chemical sediment. Sulfidic jasperoids are typical examples of silica-sulfide metasomatism of dolostones, and are found in Nevada and Iran. They are hard, dense purple-black

neg: Casius quadrangle later mission could then return samples from sites identified as probably containing remains of life. To safely bring the craft down, a 12-mile-wide, smooth, flat circle is needed. Geologists hope to examine places where water once ponded. They would like to examine sediment layers. Many places on Mars show rocks arranged in layers. A detailed discussion of layering with many Martian examples can be found in Sedimentary Geology of Mars. Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers. Layers may be formed by groundwater rising up depositing minerals and cementing sediments. The

neg: Sedimentary basin analysis use petroleum industry techniques, but in many cases they are able to study rocks at the surface. Techniques used to study surficial sedimentary rocks include: measuring stratigraphic sections, identifying sedimentary depositional environments and constructing a geologic map. An important tool in sedimentary basin analysis is sequence stratigraphy, in which various sedimentary sequences are related to pervasive changes in sea level and sediment supply. Sedimentary basin analysis Sedimentary basin analysis is a geologic method by which the history of a sedimentary basin is revealed, by analyzing the sediment fill itself. Aspects of the sediment, namely its composition, primary structures, and internal

neg: Clastic rock and is still widely accepted by most. However, others have used the term shale to further divide mudrocks based on the percentage of clay constituents. The plate-like shape of clay allows its particles to stack up one on top of another creating laminae or beds. The more clay present in a given specimen, the more laminated a rock is. Shale, in this case, is reserved for mudrocks that are laminated, while mudstone refers those that are not. Siliciclastic rocks initially form as loosely packed sediment deposits including gravels, sands, and muds. The process of turning loose sediment into hard sedimentary

neg: Sedimentary budget area. Sediment sinks can include longshore drift of sediment away from an area and sediment deposition into an estuary. Anthropogenic activities can also influence sedimentary budgets; in particular damming of a river and in stream gravel mining of a river bed can reduce the sediment source to the coast. In contrast beach nourishment can increase sediment source. In 1966, Bowen and Inman defined a littoral cell and separated sediment inputs, accretion by longshore drift and outputs. Sedimentary budgets are used to assist in the management of beach erosion by trying to show the present sediment movement and forecast future sediment

neg: West Rock Ridge in faults created by the rifting apart of North America from Eurasia and Africa over a period of 20 million years. Erosion occurring between the eruptions deposited deep layers of sediment between the lava flows and around the dike, which formed sedimentary rocks. The resulting "layer cake" of igneous and sedimentary sheets was later faulted and tilted upward. Subsequent erosion wore away the weaker sedimentary layers a faster rate than the lava layers, leaving the abruptly tilted edges of the lava sheets exposed, creating the distinct linear ridge and dramatic cliff faces visible today along the Metacomet Ridge. West Rock

neg: Varve and often when the lake surface freezes, fine clay-size sediment is deposited forming a dark coloured laminaset. In addition to seasonal variation of sedimentary processes and deposition, varve formation requires the absence of bioturbation. Consequently, varves commonly form under anoxic conditions. A well-known marine example of varve sediments are those found in the Santa Barbara basin, off California. Varve A varve is an annual layer of sediment or sedimentary rock. The word 'varve' derives from the Swedish word "varv" whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as "Hvarfig lera" (varved clay) on the

neg: Rhythmite Rhythmite A rhythmite consists of layers of sediment or sedimentary rock which are laid down with an obvious periodicity and regularity. They may be created by annual processes such as seasonally varying deposits reflecting variations in the runoff cycle, by shorter term processes such as tides, or by longer term processes such as periodic floods. Rhythmites serve a significant role in unraveling prehistoric events, providing insights into sea level change, glaciation change, and earth's orbital variations which serve to answer questions about climate change. Annually laminated deposits or varves are rhythmites with annual periodicity: annual layers of sediment or sedimentary

neg: Clastic rock surface. The changes that occur during this diagenetic phase mainly relate to the reworking of the sediments. Compaction and grain repacking, bioturbation, as well as mineralogical changes all occur at varying degrees. Due to the shallow depths, sediments undergo only minor compaction and grain rearrangement during this stage. Organisms rework sediment near the depositional interface by burrowing, crawling, and in some cases sediment ingestion. This process can destroy sedimentary structures that were present upon deposition of the sediment. Structures such as lamination will give way to new structures associated the activity of organisms. Despite being close to the surface, eogenesis

neg: Aggradation millions of years, an aggradational environment will become a sedimentary basin, which contains the deposited sediment, including paleochannels and ancient floodplains. Aggradation can be caused by changes in climate, land use, and geologic activity, such as volcanic eruption, earthquakes, and faulting. For example, volcanic eruptions may lead to rivers carrying more sediment than the flow can transport: this leads to the burial of the old channel and its floodplain. In another example, the quantity of sediment entering a river channel may increase when climate becomes drier. The increase in sediment is caused by a decrease in soil binding that results

neg: Lamination (geology) anoxic circumstances, or when the sedimentation rate was high and the sediment was buried before bioturbation could occur. Lamination develops in fine grained sediment when fine grained particles settle, which can only happen in quiet water. Examples of sedimentary environments are deep marine (at the seafloor) or lacustrine (at the bottom of a lake), or mudflats, where the tide creates cyclic differences in sediment supply. Laminae formed in glaciolacustrine environments (in glacier lakes) are a special case. They are called varves. Quaternary varves are used in stratigraphy and palaeoclimatology to reconstruct climate changes during the last few hundred thousand years.

neg: Sedimentary budget reversal of southern currents transporting sediment to the south. In contrast the Canterbury Bight has a combination of high energy environments and strong southern longshore currents that transport large amounts of sediment north, which can be classified as a sink, putting a deficit to the coasts sedimentary budget. As a result, there is erosion of the Canterbury Bight and a predominantly balanced New Brighton Spit. Models have been developed for measuring longshore drift which can assist in determining a sedimentary budget, if they are integrated over the correct timescale. The sediment budget takes into consideration sediment sources and sinks within

neg: Diagenesis Diagenesis Diagenesis () is the change of sediments or existing sedimentary rocks into a different sedimentary rock during and after rock formation (lithification), at temperatures and pressures less than that required for the formation of metamorphic rocks. It does not include changes from weathering. It is any chemical, physical, or biological change undergone by a sediment after its initial deposition, after its lithification. This process excludes surface alteration (weathering) and metamorphism. These changes happen at relatively low temperatures and pressures and result in changes to the rock's original mineralogy and texture. There is no sharp boundary between diagenesis and metamorphism,

neg: Sedimentary rock by shallow marine deposits and molasse. In many cases facies changes and other lithological features in sequences of sedimentary rock have a cyclic nature. This cyclic nature was caused by cyclic changes in sediment supply and the sedimentary environment. Most of these cyclic changes are caused by astronomic cycles. Short astronomic cycles can be the difference between the tides or the spring tide every two weeks. On a larger time-scale, cyclic changes in climate and sea level are caused by Milankovitch cycles: cyclic changes in the orientation and/or position of the Earth's rotational axis and orbit around the Sun. There

neg: Talcott Mountain of cliffs west of Heublein Tower. The basalt cliffs are the product of several massive lava flows hundreds of feet deep that welled up in faults created by the rifting apart of North America from Eurasia and Africa. These basalt floods of lava happened over a period of 20 million years. Erosion occurring between the eruptions deposited deep layers of sediment between the lava flows, which eventually lithified into sedimentary rock. The resulting "layer cake" of basalt and sedimentary sheets eventually faulted and tilted upward. Subsequent erosion wore away the weaker sedimentary layers at a faster rate than the basalt

neg: Sleeping Giant (Connecticut) are visible beneath many of the ledges of Sleeping Giant. The basalt cliffs are the product of several massive lava flows hundreds of feet deep that welled up in faults created by the rifting apart of North America from Eurasia and Africa. These basalt floods of lava happened over a period 20 million years. Erosion occurring between the eruptions deposited deep layers of sediment between the lava flows, which eventually lithified into sedimentary rock. The resulting "layer cake" of basalt and sedimentary sheets eventually faulted and tilted upward. Subsequent erosion wore away the weaker sedimentary layers at a faster rate

neg: Metacomet Trail lava flows hundreds of feet deep that welled up in faults created by the rifting apart of North America from Eurasia and Africa. The basalt floods of lava occurred over a period of 20 million years. Erosion occurring between the eruptions deposited deep layers of sediment between the lava flows, which eventually lithified into sedimentary rock. The resulting "layer cake" of basalt and sedimentary sheets eventually faulted and tilted upward. Subsequent erosion wore away the weaker sedimentary layers a faster rate than the basalt layers, leaving the abruptly tilted edges of the basalt sheets exposed, creating the distinct linear ridge

neg: Geology of the United States volcanic rocks and slivers of ancient sea floor. These mountains were once part of a mighty uplifted mountain range that stretch from the Appalachian Highlands through Texas. During the earliest Paleozoic Era, the continent that would later become North America straddled the equator. The Appalachian region was a passive plate margin, not unlike today's Atlantic Coastal Plain Province. During this interval, the region was periodically submerged beneath shallows seas. Thick layers of sediment and carbonate rock was deposited on the shallow sea bottom when the region was submerged. When seas receded, terrestrial sedimentary deposits and erosion dominated. During the middle

neg: Rock microstructure or other authigenic minerals forming in low-grade metamorphic conditions. Sorting is used to describe the uniformity of grain sizes within a sedimentary rock. Understanding sorting is critical to making inferences on the degree of maturity and length of transport of a sediment. Sediments become sorted on the basis of density, because of the energy of the transporting medium. High energy currents can carry larger fragments. As the energy decreases, heavier particles are deposited and lighter fragments continue to be transported. This results in sorting due to density. Sorting can be expressed mathematically by the standard deviation of the grain-size frequency

neg: Ball-and-pillow structures Ball-and-pillow structures Ball-and-pillow structures are masses of clastic sediment that take the form of isolated pillows or protruding ball structures. These soft-sediment deformations are usually found at the base of sandstone beds that are interbedded with mudstone. It is also possible to find ball-and-pillows in limestone beds that overlie shale, but it's less common. They are normally hemispherical or kidney shaped, and range in size from a few inches to several feet. Ball-and-pillow deformations are a result of a physical shock that has been applied to unconsolidated sediment. This shock causes rupturing to occur in the sedimentary rock layer, which

neg: Hoffer Creek than above sea level at the highest. Hoffer Creek is in the Ridge and Valley physiographic province. The surface geology in the watershed of Hoffer Creekincluding an adjacent unnamed tributary to the Susquehanna Riveris dominated by interbedded sedimentary rock, which underlies 70 percent of the watershed. Sandstone occupies another 25 percent of the watershed's area. The remaining 5 percent is split between carbonate rock (4 percent) and conglomerate (1 percent). The geology of the watershed has little influence on the creek's sediment load. The level of slope in the watershed of Hoffer Creek, combined with the lack of conservation farming

neg: Pelite Pelite A pelite (Ancient Greek "pelos", clay) is a metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone. The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, i.e. mud or a mudstone, the metamorphosed version of which would technically have been a "metapelite". It was equivalent to the now little-used Latin-derived term lutite. A semipelite is defined in part as having similar chemical composition but being of a crystalloblastic nature. The term "pelite" is not to be confused with "pilite", a rarely used name for an altered olivine that has been partially pseudomorphically

neg: Principle of lateral continuity However, as the amount of material lessens away from the source, the layer of that material will become thinner. Often, coarser-grained material can no longer be transported to an area because the transporting medium has insufficient energy to carry it to that location. In its place, the particles that settle from the transporting medium will be finer-grained, and there will be a lateral transition from coarser- to finer-grained material. The lateral variation in sediment within a stratum is known as sedimentary facies. If sufficient sedimentary material is available, it will be deposited up to the limits of the sedimentary basin.

neg: Peperite in the cooling magma, pore-water steam explosions and magma-sediment density contrasts. The main mechanism suggested for mingling of the igneous clasts with the sediment is fluidisation, in the sense of particle support and transport by a fluid. Peperites are found world-wide in sediments with a significant water content at the time of formation associated with igneous rocks covering the compositional range from basalt to rhyolite. Peperite A peperite is a type of volcaniclastic rock consisting of sedimentary rock that contains fragments of younger igneous material and is formed when magma comes into contact with wet sediments. The term was originally

neg: Geology of the Appalachians elevations similar to those of the Alps and the Rocky Mountains before they were eroded. During the earliest Paleozoic Era, the continent that would later become North America straddled the equator. The Appalachian region was a passive plate margin, not unlike today's Atlantic Coastal Plain Province. During this interval, the region was periodically submerged beneath shallow seas. Thick layers of sediment and carbonate rock were deposited on the shallow sea bottom when the region was submerged. When seas receded, terrestrial sedimentary deposits and erosion dominated. During the middle Ordovician Period (about 440-480 million years ago), a change in plate motions

neg: Lithostratigraphy Lithostratigraphy Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general a stratum will be primarily igneous or sedimentary relating to how the rock was formed. Sedimentary layers are laid down by deposition of sediment associated with weathering processes, decaying organic matters (biogenic) or through chemical precipitation. These layers are distinguishable as having many fossils and are important for the study of biostratigraphy. Igneous layers are either plutonic or volcanic in character depending upon the cooling rate of the rock. These layers

neg: Shark tooth of . The smaller teeth ranging from 3½" and 4½" are more common finds, while teeth over 5", 6", and 7" are more rare. These teeth are in extremely high demand by collectors and private investors, and they can fetch steep prices according to their size and deterioration. The larger teeth can cost as much as 3,000 dollars. Shark teeth cannot be collected from just any type of rock. Any fossils, including fossil shark teeth, are preserved in sedimentary rocks after falling from their mouth. The sediment that the teeth were found in is used to help determine the age

neg: Sedimentary rock swamps, lakes and lagoons, fine sediment is deposited, mingled with organic material from dead plants and animals. In rivers, the energy of the water is much greater and can transport heavier clastic material. Besides transport by water, sediment can in continental environments also be transported by wind or glaciers. Sediment transported by wind is called aeolian and is always very well sorted, while sediment transported by a glacier is called glacial till and is characterized by very poor sorting. Aeolian deposits can be quite striking. The depositional environment of the Touchet Formation, located in the Northwestern United States, had intervening

neg: Sedimentary budget river systems. Based annualized estimates of magnitude of sediment deposition, hurricanes have been found to deposit hundreds of times more sediment in these coastal wetland regions than man-made river diversions intended to redirect river-transported sediment to starving wetland systems. For salt marsh wetlands, particularly those of coastal Louisiana, sediment accumulation from hurricanes is "sufficient" to account for the entire inorganic sedimentary budget. Estuaries are an example of a coastal sink in that they tend to trap sediment which can be due to tidal circulations and the mixing of fresh and salt water, the injection of river sediment and the presence

neg: Sedimentary budget sediment removed would be used to re-nourish the Mt. Manganui beach. The sediment was deposited in the nearshore zone promoting beach accretion by offshore berm emplacement. Results show that most of the 80,000m of sediment added to the nearshore zone made it to ashore to re-nourish the beach and even out the past sediment deficit. Nourishment of a coast can be regarded as a fast fix option to reversing a sediment deficit; however, it is important that nourishment is on-going in order to ensure the sedimentary budget remains balanced. When protecting the coastline it is important to understand the how

neg: Robert Frost Trail (Massachusetts) North America from Eurasia and Africa over a period of 20 million years. Basalt is a dark colored rock, but the iron within it weathers to a rusty brown when exposed to the air, lending it a distinct reddish appearance. Huge slopes made of fractured basalt scree, such as the one beneath the cliffs on Bare Mountain, are common. Erosion occurring between the eruptions deposited deep layers of sediment between the lava flows, which eventually lithified into sedimentary rock, such as the conglomerate rock Mount Toby is composed of. The resulting "layer cake" of basalt and sedimentary sheets eventually faulted

neg: Sedimentary basin that penetrated the basement are in the Eastern Dahomey embayment of western Nigeria. A maximum thickness of about 12,000 m of sedimentary rocks is attained in the offshore western Niger delta, but maximum thicknesses of sedimentary rocks are about 2,000 m in the Chad basin and only 500 m in the Sokoto embayment. As more and more sediment is deposited into the basin, the weight of all the newer sediment may cause the basin to subside further because of isostasy. A basin can continue having sediment deposited into it, and continue to subside, for long periods of geological time; this

neg: Maturity (sedimentology) Maturity (sedimentology) In sedimentary geology, maturity describes the composition and texture of grains in clastic rocks, most typically sandstones, resulting from different amounts of sediment transportation. A sediment is mature when the grains in a sediment become well-sorted and well-rounded due to weathering or abrasion of the grains during transport. There are two components to describe maturity, "texture" and "composition". Texture describes how rounded and sorted the sample is while composition describes how much the composition trends toward stable minerals and components. A mature sediment is more uniform in appearance, for the sediment grains are well rounded, are of a

neg: Ramapo Fault sediment, sand, and mud. East of this province is the Highlands. This province is composed of the oldest rocks in the region – gneiss, granite, and Precambrian marble – formed by melting sedimentary rock which recrystallized in a deformed state. Paleozoic rock belts are also present in the area. East of the Highlands is the Piedmont, specifically the Newark Basin. The Ramapo Fault forms the boundary between the Newark Basin and the Highlands, running from Haverstraw, New York to near Schaefferstown, Pennsylvania. The Newark Basin, an aborted rift valley created during the breakup of Pangaea, consists of sedimentary and volcanic

neg: Ooid Ooid Ooids are small (commonly ≤2 mm in diameter), spheroidal, "coated" (layered) sedimentary grains, usually composed of calcium carbonate, but sometimes made up of iron- or phosphate-based minerals. Ooids usually form on the sea floor, most commonly in shallow tropical seas (around the Bahamas, for example, or in the Persian Gulf). After being buried under additional sediment, these ooid grains can be cemented together to form a sedimentary rock called an "oolite". Oolites usually consist of calcium carbonate; these belong to the limestone rock family. Pisoids are similar to ooids, but are larger than 2 mm in diameter, often considerably

neg: Shallow water marine environment cannot always coexist, it is possible to have a shallow marine environment composed solely of carbonaceous sediment or one that is composed completely of siliciclastic sediment. Shallow water marine sediment is made up of larger grain sizes, because smaller grains have been washed out to deeper water. Within sedimentary rocks composed of carbonaceous sediment, there may also be evaporite minerals. The most common evaporite minerals found within modern and ancient deposits are gypsum, anhydrite, and halite; they can occur as crystalline layers, isolated crystals or clusters of crystals. In terms of geologic time, it is said that most Phanerozoic sedimentary

neg: Rock cycle the rocks involved. The result is regional metamorphism within the interior of the ensuing orogeny or mountain building event. As the two masses are compressed, folded and faulted into a mountain range by the continental collision the whole suite of pre-existing igneous, volcanic, sedimentary and earlier metamorphic rock units are subjected to this new metamorphic event. The high mountain ranges produced by continental collisions are immediately subjected to the forces of erosion. Erosion wears down the mountains and massive piles of sediment are developed in adjacent ocean margins, shallow seas, and as continental deposits. As these sediment piles are buried

neg: Hanging Hills by the rifting apart of North America from Eurasia and Africa. These basalt floods of lava happened over a period of 20 million years. Erosion occurring between the eruptions deposited deep layers of sediment between the lava flows, which eventually lithified into sedimentary rock. The resulting "layer cake" of basalt and sedimentary sheets eventually faulted and tilted upward. Subsequent erosion wore away the weaker sedimentary layers a faster rate than the basalt layers, leaving the abruptly tilted edges of the basalt sheets exposed, creating the distinct linear ridge and dramatic cliff faces visible today. The best way to imagine this

neg: Sedimentary rock are a number of Milankovitch cycles known, lasting between 10,000 and 200,000 years. Relatively small changes in the orientation of the Earth's axis or length of the seasons can be a major influence on the Earth's climate. An example are the ice ages of the past 2.6 million years (the Quaternary period), which are assumed to have been caused by astronomic cycles. Climate change can influence the global sea level (and thus the amount of accommodation space in sedimentary basins) and sediment supply from a certain region. Eventually, small changes in astronomic parameters can cause large changes in sedimentary environment

neg: Geology of the Falkland Islands wells indicate a potentially productive source rock, they also indicate that many of the target reservoirs are composed of volcaniclastic rocks with low porosity due to secondary mineralisation and are thus unlikely to store hydrocarbons in large quantities. This is not an anomalous view based solely on published data from one well, but based on information from multiple sources. Volcaniclastic-rich deposits are probably present in many parts of the basin, which is to be expected, given the major volcanic sediment source that lay to the west at the time of sedimentary deposition. The sedimentary material that fills the north part

neg: Vegetation-induced sedimentary structures Vegetation-induced sedimentary structures Vegetation-induced sedimentary structures (VISS) are primary sedimentary structures formed by the interaction of detrital sediment with "in situ" plants. VISS provide physical evidence of vegetation's fundamental role in mediating sediment accumulation and erosion in clastic depositional environments. VISS can be broken into seven types, five being hydrodynamic and two being decay-related. The simple hydrodynamic VISS are categorized by centroclinal cross strata, scratch semicircles and upturned beds. The complex hydrodynamic VISS are categorized by coalesced scour fills and scour-and-mound beds. The decay-related VISS are categorized by mudstone-filled hollows and downturned beds. Upturned beds are mounds of elongated sediment

neg: Compact Reconnaissance Imaging Spectrometer for Mars Terra Arabia - have horizontally layered, light-toned rocks. Follow-up observations of those rocks' mineralogy by OMEGA found that some are rich in sulfate minerals, and that other layered rocks around Mawrth Vallis are rich in phyllosilicates. Both class of minerals are signatures of sedimentary rocks. CRISM has used its improved spatial resolution to look for other deposits of sedimentary rock on Mars' surface, and for layers of sedimentary rock buried between layers of volcanic rock in Mars' crust. To understand Mars' ancient climate, and whether it might have created environments habitable for life, first we need to understand Mars' climate