sediment

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Related to Bedload: dissolved load, Suspended load

sediment

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 rock).

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 floodplains or carry these particles to the ocean, where they may be deposited as a delta. Ocean sediments, especially in the form of turbidites, are usually deposited at the foot of continental slopes (see oceans). 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 conglomerates; sands become sandstone; and muds become shale. 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).
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Sediment

Transported and deposited particles or aggregates derived from rocks, soil, or biological material.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved

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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

sediment

The matter which settles to the bottom of water or any other liquid.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

sediment

material that has been deposited from water, ice, or wind
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
(1996) also argue that the plain was laid down during periods of high bedload. The final paleophase ended when climatic change ~12 000 years before present diminished the size and peak of flows and reduced the bedload accordingly.
The Nagri Formation was most probably deposited by sandy bedload braided fluvial system.
The second set was used to catch the sediments, transported as bedload onto two plates with slopes of 15[degrees] and 25[degrees].
y Beschta R.L., "A model of two-phase bedload transport in an Oregon Coast Range stream", Earth Surface Processes and Landforms, 7, (1982) 517-527.
Estimations of bedload sediment transport in the Guadiana estuary (SW Iberian peninsula) during low river discharge periods.
where qbi is fractional bedload transport rate for grain size fraction i (gr/s/m), [[rho].sub.s] is sediment density (kg/[m.sup.3]), [rho] is density of water (kg/[m.sup.3]), g is the acceleration due to gravity (m/[s.sup.2]), fi is proportion of grain size fraction i on the bed, U* is bed shear velocity (m/s), [[tau].sub.i] is time-averaged bed shear stress for grain size fraction i (N/[m.sup.2]) and [D.sub.i] is grain size fraction i (mm).
As indicated from the discussion concerning average shear force of the flowing water and the critical bed shear force of the streambed, the bedload represents the armor that resists erosion.
A hydrology project at Redwood National Park helped geologists monitor the shifts in bedload in an aggraded stream along which the tallest redwood trees occur.
The complex landscape of the Arboretum was formed by processes including deposition of bedload material by the glacier, deposition of sediment by glacial meltwater, melting of stagnant ice, inundation by water of Glacial Lake Maumee, and flooding by the Huron River.
During these events, bedload transport is directed to the south with an offshore component, and suspended sediments are directed mainly along the coast to the southwest.
The critical shear stress ([[tau].sub.cr]) represents the necessary boundary shear stress to move the bedload materials, based upon their grain size, grain shape, sorting, effective density, and roughness.
They are either bedload deposits (dune sand, sheet sand) or suspended load (loess) of wind systems that were effective in moving sediment.