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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).


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


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.


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


material that has been deposited from water, ice, or wind
References in periodicals archive ?
Despite that, the typical formulas and relationships that are used to describe sediment flux in most other rivers don't work for the Huanghe," Nittrouer said.
Because of the high flow caused by precipitation, the stream sediment characteristics changed dramatically during the study, with a decrease in the E.
Results of Scenario-1 indicates that power units can safely operate for 21 days without any stoppage to flush sedimentation in the sand trap when the diversion flow carries sediment concentration of 0.
The aims of this study were (1) to determine the distribution of P-fractions in the surficial sediments of the large shallow eutrophic Lake Peipsi, (2) to estimate the relationships between the P concentration dynamics in the sediment surface and in the overlying water, (3) to assess the influence of [O.
One of the most important parameters which effect the strength of secondary flow and therefore sediment entry is the vane angle relative to the flow direction.
In the process of pesticides adsorption to sediment, we can determine the concentration of pesticides in water and sediment to study its behavior in the aquatic environment [6].
Data from the study was used to develop models to predict the rate of alum application that would be needed to mitigate phosphorus release from contaminated sediments, based on sediment properties.
1994 and many others) were not as detailed; therefore, the probable deviations caused by the insufficient stabi lization of sediment distribution could not be detected and studied.
Through tracing river sediments back to their source, Queensland scientists have now found that sediment load for the whole catchment could effectively be halved by rehabilitating stream banks and the major gullies.
In California's Central Valley, for example, there are 11 water-body segments listed as 'impaired' under the draft 2008 Clean Water Act Section 303(d) list, due to sediment toxicity of agricultural origin.
Samples of lakebed sediment suggest that the tracks were formed near the end of the last ice age, about 10,000 years ago.
Key words: hydrology, sediment transport, fluvial geomorphology, snow, meltwater ponding, sediment storage, Melville Island, erosion