Silt in the context of Mud flat

Sediment is a solid material made of loose particles that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and 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; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification.

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 deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. Glacial moraine deposits and till are ice-transported sediments.

The Sea of Azov is an inland shelf sea in Eastern Europe connected to the Black Sea by the narrow (about 4 km (2.5 mi)) Strait of Kerch, and sometimes regarded as a northern extension of the Black Sea. The sea is bounded by Russia on the east, and by Ukraine on the northwest and southwest (the parts of Ukraine bordering the sea are currently under Russian occupation). It is an important access route for Central Asia, from the Caspian Sea via the Volga–Don Canal.

The sea is largely affected by the inflow of the Don, Kuban, and other rivers, which bring sand, silt, and shells, which in turn form numerous bays, limans, and narrow spits. Because of these deposits, the sea bottom is relatively smooth and flat, with the depth gradually increasing toward the middle. Because of the river inflow, water in the sea has low salinity and a high amount of biomass (such as green algae) that affects the water colour. Abundant plankton result in unusually high fish productivity. The sea shores and spits are low; they are rich in vegetation and bird colonies. The Sea of Azov is the shallowest sea in the world, with the depth varying between 0.9 and 14 metres (3 and 46 ft). There is a constant outflow of water from the Sea of Azov to the Black Sea.

A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge. The soils usually consist of clays, silts, sands, and gravels deposited during floods.

Because of regular flooding, floodplains frequently have high soil fertility since nutrients are deposited with the flood waters. This can encourage farming; some important agricultural regions, such as the Nile and Mississippi river basins, heavily exploit floodplains. Agricultural and urban regions have developed near or on floodplains to take advantage of the rich soil and freshwater. However, the risk of inundation has led to increasing efforts to control flooding.

The Nile (also known as the Nile River or River Nile) is an important river in Africa that flows northwards into the Mediterranean Sea. At roughly 6,650 km (4,130 mi) long, it is among the longest rivers in the world. Its drainage basin covers eleven countries: the Democratic Republic of the Congo, Tanzania, Burundi, Rwanda, Uganda, Kenya, Ethiopia, Eritrea, South Sudan, Sudan, and Egypt. It plays an important economic role in the economy of these nations, and it is the primary water source for South Sudan, Sudan and Egypt.

The Nile has two major tributaries: the White Nile and the Blue Nile. The White Nile, being the longer, is traditionally considered to be the headwaters, while the Blue Nile actually contributes 80% of the water and silt below the confluence of the two. The White Nile begins at Lake Victoria and flows through Uganda and South Sudan, while the Blue Nile begins at Lake Tana in Ethiopia and flows into Sudan from the southeast. The two rivers meet at the Sudanese capital of Khartoum.

Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.

The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO₂), usually in the form of quartz.

Yeşilova Höyük is a höyük (tell) in the Bornova district of İzmir, Turkey, and is the oldest known prehistoric human settlement in the area of İzmir. It was occupied continuously from roughly 6500 to 4000 BC, and was covered with silt afterwards.

Discovered in 2003, the site has been explored since 2005 by a team under the direction of Associate Professor Zafer Derin of Ege University. By 2005, important new light had been shed on the Neolithic-Chalcolithic phases of İzmir's metropolitan area in particular and of Turkey's Aegean Region in general.

Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.

Although its permeability and porosity is relatively low, siltstone is sometimes a tight gas reservoir rock, an unconventional reservoir for methane gas that requires hydraulic fracturing for economic gas production.

Loess (US: /ˈlɛs, ˈlʌs, ˈloʊ.əs/, UK: /ˈloʊ.əs, ˈlɜːs/; from German: Löss [lœs]) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loesses or similar deposits.

Loess is a periglacial or aeolian (windborne) sediment, defined as an accumulation of 20% or less of clay with a balance of roughly equal parts sand and silt (with a typical grain size from 20 to 50 micrometers), often loosely cemented by calcium carbonate. Usually, they are homogeneous and highly porous and have vertical capillaries that permit the sediment to fracture and form vertical bluffs.

An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 and 6,000 metres (9,800 and 19,700 ft). Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. They are among the flattest, smoothest, and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins, the other elements being an elevated mid-ocean ridge and flanking abyssal hills.

The creation of the abyssal plain is the result of the spreading of the seafloor (plate tectonics) and the melting of the lower oceanic crust. Magma rises from above the asthenosphere (a layer of the upper mantle), and as this basaltic material reaches the surface at mid-ocean ridges, it forms new oceanic crust, which is constantly pulled sideways by spreading of the seafloor. Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited by turbidity currents that have been channelled from the continental margins along submarine canyons into deeper water. The rest is composed chiefly of pelagic sediments. Metallic nodules are common in some areas of the plains, with varying concentrations of metals, including manganese, iron, nickel, cobalt, and copper. There are also amounts of carbon, nitrogen, phosphorus and silicon, due to material that comes down and decomposes.

The Shatt al-Arab (Arabic: شط العرب, lit. 'River of the Arabs') is a river about 200 kilometres (120 mi) in length that is formed at the confluence of the Euphrates and Tigris rivers in the town of al-Qurnah in the Basra Governorate of southern Iraq. The southern end of the river constitutes the Iran–Iraq border down to its mouth, where it discharges into the Persian Gulf. The Shatt al-Arab varies in width from about 232 metres (761 ft) at Basra to 800 metres (2,600 ft) at its mouth. It is thought that the waterway formed relatively recently in geological time, with the Tigris and Euphrates originally emptying into the Persian Gulf via a channel further to the west. Kuwait's Bubiyan Island is part of the Shatt al-Arab delta.

The Karun, a tributary which joins the waterway from the Iranian side, deposits large amounts of silt into the river; this necessitates continuous dredging to keep it navigable.

An aquifer is an underground layer of water-bearing material consisting of permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related concepts include aquitard, a bed of low permeability along an aquifer, and aquiclude (or aquifuge), a solid and impermeable region underlying or overlying an aquifer, the pressure of which could lead to the formation of a confined aquifer. Aquifers can be classified as saturated versus unsaturated; aquifers versus aquitards; confined versus unconfined; isotropic versus anisotropic; porous, karst, or fractured; and transboundary aquifer.

Groundwater from aquifers is sustainably harvested by humans through the use of qanats leading to a well. This groundwater is mainly used for agricultral purposes but is used for other reasons such as home use, industrial use and is sometimes used as a source of renewable energy. Groundwater is a major source of fresh water for many regions, although it can present various challenges for the environment, such as overdrafting (extracting groundwater beyond the equilibrium yield of the aquifer), groundwater-related subsidence of land, and the salinization or pollution of the groundwater.

Siltation is water pollution caused by particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments and to the increased accumulation (temporary or permanent) of fine sediments on bottoms where they are undesirable. Siltation is most often caused by soil erosion or sediment spill.

It is sometimes referred to by the ambiguous term "sediment pollution", which can also refer to a chemical contamination of sediments accumulated on the bottom, or to pollutants bound to sediment particles. Although "siltation" is not perfectly stringent, since it also includes particle sizes other than silt, it is preferred for its lack of ambiguity.

The spits of the Sea of Azov are narrow peninsulas of sand, silt and shells in the Sea of Azov. They are as long as 112 km (Arabat Spit, the world's longest spit), 45 km (Fedotov Spit), 31 km (Achuevsk Spit), 30 km (Obytichna Spit) and 23 km (Berdiansk Spit). Their total length exceeds 300 km which is larger than the width of the sea (about 180 km).

Most of the spits were formed by the deposition of sand, silt and shells by river flows into the Azov Sea bays. Therefore, many spits stretch to the south into the sea and are continuations of the (right) river banks (see table and map). The Chushka and Tuzla spits are located inside the Strait of Kerch; the former spit is formed by the outflow of water from the Azov Sea to the Black Sea and therefore also faces south, whereas the latter is facing north. A major oil spill occurred near those spits on 11 November 2007.

The Red River or the Hong River (traditional Chinese: 紅河; simplified Chinese: 红河; pinyin: Hóng Hé; Vietnamese: Sông Hồng; Chữ Nôm: 瀧紅), also known as the Sông Cái (lit. "Main River"; Chữ Nôm: 瀧丐) in Vietnamese and the Yuan River (元江, Yuán Jiāng) in Chinese, is a 1,149-kilometer (714 mi)-long river that flows from Yunnan in Southwest China through northern Vietnam to the Gulf of Tonkin. According to C. Michael Hogan, the associated Red River Fault was instrumental in forming the entire South China Sea at least as early as 37 million years before present. The name red and southern position in China are associated in traditional cardinal directions. The river is relatively shallow, and carries a lot of reddish silt along its way, appearing red brown in colour.