Deposition (geology)
Encyclopedia
Deposition is the geological
process by which material is added to a landform
or land mass. Fluids such as wind and water, as well as sediment
flowing via gravity, transport previously eroded
sediment, which, at the loss of enough kinetic energy
in the fluid, is deposited, building up layers of sediment.
Deposition occurs when the forces responsible for sediment transportation are no longer sufficient to overcome the forces of particle weight
and friction
, creating a resistance to motion. Deposition can also refer to the buildup of sediment from organically derived matter
or chemical processes
. For example, chalk
is made up partly of the microscopic calcium carbonate
skeletons of marine plankton
, the deposition of which has induced chemical processes (diagenesis
) to deposit further calcium carbonate. Similarly, the formation of coal
begins with deposition of organic material, mainly from plants, in anaerobic
conditions.
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
process by which material is added to a landform
Landform
A landform or physical feature in the earth sciences and geology sub-fields, comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography...
or land mass. Fluids such as wind and water, as well as sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
flowing via gravity, transport previously eroded
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
sediment, which, at the loss of enough kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
in the fluid, is deposited, building up layers of sediment.
Deposition occurs when the forces responsible for sediment transportation are no longer sufficient to overcome the forces of particle weight
Weight
In science and engineering, the weight of an object is the force on the object due to gravity. Its magnitude , often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g; thus:...
and friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
, creating a resistance to motion. Deposition can also refer to the buildup of sediment from organically derived matter
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
or chemical processes
Chemical process
In a "scientific" sense, a chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. Such a chemical process can occur by itself or be caused by somebody. Such a chemical process commonly involves a chemical reaction of some sort...
. For example, chalk
Chalk
Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....
is made up partly of the microscopic calcium carbonate
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
skeletons of marine plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
, the deposition of which has induced chemical processes (diagenesis
Diagenesis
In geology and oceanography, diagenesis is any chemical, physical, or biological change undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface alteration and metamorphism. These changes happen at relatively low temperatures and pressures...
) to deposit further calcium carbonate. Similarly, the formation of coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
begins with deposition of organic material, mainly from plants, in anaerobic
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
conditions.
See also
- CementationCementationCementation may refer to:*Cementation , the process of deposition of dissolved mineral components in the interstices of sediments*Cementation , a small deposit of calcium, similar to a cyst...
- Cross-beddingCross-beddingIn geology, the sedimentary structures known as cross-bedding refer to horizontal units that are internally composed of inclined layers. This is a case in geology in which the original depositional layering is tilted, and the tilting is not a result of post-depositional deformation...
- DiagenesisDiagenesisIn geology and oceanography, diagenesis is any chemical, physical, or biological change undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface alteration and metamorphism. These changes happen at relatively low temperatures and pressures...
- OverbankOverbankThe term overbank describes the type of alluvial geological deposit or sediment that is deposited on the flood plain of a river. Because it occurs outside the main channel, away from faster flow, the deposit tends to be fine-grained....
- Sedimentary rockSedimentary rockSedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
- SedimentSedimentSediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
- Sediment transportSediment transportSediment transport is the movement of solid particles , typically due to a combination of the force of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained...
- Sedimentary structuresSedimentary structuresSedimentary structures are those structures formed during sediment deposition.Sedimentary structures such as cross bedding, graded bedding and ripple marks are utilized in stratigraphic studies to indicate original position of strata in geologically complex terrains and understand the depositional...
- Geologists
- Shen KuoShen KuoShen Kuo or Shen Gua , style name Cunzhong and pseudonym Mengqi Weng , was a polymathic Chinese scientist and statesman of the Song Dynasty...
- 11th century Chinese scientist - Georgius Agricola - 16th century German sciences
- Shen Kuo