sediment


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sediment,

mineral or organic particles that are deposited by the action of wind, water, or glacial ice. These sediments can eventually form sedimentary rocks (see rockrock,
aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and metamorphic.
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).

Classification of Sediments

Sediments are commonly subdivided into three major groups—mechanical, chemical, and organic.

Mechanical, or clastic, sediments are derived from the erosion of earlier formed rocks on the earth's surface or in the oceans. These are then carried by streams, winds, or glaciers to the site where they are deposited. Streams deposit sediment in floodplainsfloodplain,
level land along the course of a river formed by the deposition of sediment during periodic floods. Floodplains contain such features as levees, backswamps, delta plains, and oxbow lakes.
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 or carry these particles to the ocean, where they may be deposited as a deltadelta
[from triangular shape of the Nile delta, like the Greek letter delta], a deposit of clay, silt, and sand formed at the mouth of a river where the stream loses velocity and drops part of its sediment load.
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. Ocean sediments, especially in the form of turbidites, are usually deposited at the foot of continental slopes (see oceansocean,
interconnected mass of saltwater covering 70.78% of the surface of the earth, often called the world ocean. It is subdivided into four (or five) major units that are separated from each other in most cases by the continental masses. See also oceanography.
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). Glaciers carry sediment frozen within the mass of the ice and are capable of carrying even huge boulders (erratics).

Chemical sediments are formed by chemical reactions in seawater that result in the precipitation of minute mineral crystals, which settle to the floor of the sea and ultimately form a more or less chemically pure layer of sediment. For example, evaporation in shallow basins results in a sequence of evaporite sediments, which include gypsum and rock salt.

Organic sediments are formed as a result of plant or animal actions; for example, peat and coal form by the incomplete decay of vegetation and its later compaction. Deep-ocean sediment known as pelagic ooze consists largely of the remains of microscope organisms (mostly foraminifera and diatoms) from the overlying waters as well as minor amounts of windblown volcanic and continental dust. Limestones are commonly formed by the aggregation of calcite shells of animals.

Formation of Sedimentary Rock

Sediments form sedimentary rock by compaction and cementation of the particles. Thus, coarse sediments become conglomeratesconglomerate,
in geology, sedimentary rock composed largely of pebbles or other rounded particles whose diameter is larger than 2 mm (.08 in.). Essentially a cemented gravel, conglomerates are formed along beaches, as glacial drift, and in river deposits.
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; sands become sandstonesandstone,
sedimentary rock formed by the cementing together of grains of sand. The usual cementing material in sandstone is calcium carbonate, iron oxides, or silica, and the hardness of sandstone varies according to the character of the cementing material; quartz sandstones
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; and muds become shaleshale,
sedimentary rock formed by the consolidation of mud or clay, having the property of splitting into thin layers parallel to its bedding planes. Shale tends to be fissile, i.e., it tends to split along planar surfaces between the layers of stratified rock.
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. Sedimentary rocks make up only about 5% of all rocks of the earth's crust, yet they cover 75% of the land area in a veneer that averages 2.26 km (1.4 mi) in thickness, ranging from 0 to 12.9 km (0–8 mi).

Sediment

Transported and deposited particles or aggregates derived from rocks, soil, or biological material.

sediment

[′sed·ə·mənt]
(geology)
A mass of organic or inorganic solid fragmented material, or the solid fragment itself, that comes from weathering of rock and is carried by, suspended in, or dropped by air, water, or ice; or a mass that is accumulated by any other natural agent and that forms in layers on the earth's surface such as sand, gravel, silt, mud, fill, or loess.
A solid material that is not in solution and either is distributed through the liquid or has settled out of the liquid.

sediment

The matter which settles to the bottom of water or any other liquid.

sediment

material that has been deposited from water, ice, or wind
References in periodicals archive ?
Delta 'drowning' can be offset by a sustained supply of sediment. It is therefore crucial to know how sediment delivery will change in the future.
Frances Dunn with colleagues at the University of Southampton and elsewhere explored this question using computer modelling to project changes in sediment delivery.
ISLAMABAD -- Total sediments deposited in Tarbela reservoir from 1974 to 2017 is 4.
The principal conclusion of the study was that watershed management and upstream debris check dams could accomplish little towards reducing the quantity of the sediments inflow.
Using the observed precipitation data collected at 301 rainfall stations in the HLR from 1966 to 2016, the objectives of this study were (i) to analyze the spatial distribution and temporal variation in the annual precipitation, different precipitation classes, and rainstorm frequency and (ii) to explore the impacts of precipitation on sediment yield and quantitatively analyze the contribution of precipitation and other factors to sediment yield change.
Sediment samples were analyzed for moisture content (at 105[degrees]C for 24 h) on a dry weight approach (wet weight of the water divided by the dry weight of the sediments).
Sediment quality guidelines (SQGs) have been widely applied to assess the metal contamination levels in sediments.
Each of the river's identities -- as the fertile nurturer and the wanton killer -- derives from the same feature: the 1 billion tons of sediment that washes down each year from the Loess Plateau to the Bohai Sea.
The objective of this paper is therefore to investigate the influence of cascade hydropower exploitation on runoff and sediment transport.
Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectrometry (EDS) were adopted in this study to observe and analyze the pore microstructure and element distribution of sediment particles.
To get additional insight into these legacy organisms, we collected sediment and water samples in the Squaw Creek watershed near Ames, Iowa, during the first significant precipitation event of the season in spring 2013.
To analyze the efficiency of the Sand Trap Chamber in the Golen Gol Hydropower Project; NETNUS Numerical Simulation alongwith MATLAB and AutoCad Softwares was used to assess the effectiveness of the Sand Trap chamber by computing sedimentation load (tons) longitudinal sedimentation thickness (meters) and finally to propose an operational mode of operation for sediment flushing by considering two different scenarios i.e.