Sediments in the context of Soil series

Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope movement.

Processes that lead to subsidence include dissolution of underlying carbonate rock by groundwater; gradual compaction of sediments; withdrawal of fluid lava from beneath a solidified crust of rock; mining; pumping of subsurface fluids, such as groundwater or petroleum; or warping of the Earth's crust by tectonic forces. Subsidence resulting from tectonic deformation of the crust is known as tectonic subsidence and can create accommodation for sediments to accumulate and eventually lithify into sedimentary rock.

Deposition is the geological process in which sediments, soil and rocks are added to a landform or landmass. Wind, ice, water, and gravity transport previously weathered surface material, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of sediment.

This occurs when the forces responsible for sediment transportation are no longer sufficient to overcome the forces of gravity and friction, creating a resistance to motion; this is known as the null-point hypothesis. 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 induced chemical processes (diagenesis) to deposit further calcium carbonate. Similarly, the formation of coal begins with the deposition of organic material, mainly from plants, in anaerobic conditions.

A river mouth is where a river flows into a larger body of water, such as another river, a lake/reservoir, a bay/gulf, a sea, or an ocean. At the river mouth, sediments are often deposited due to the slowing of the current, reducing the carrying capacity of the water.The water from a river can enter the receiving body in a variety of different ways. The motion of a river is influenced by the relative density of the river compared to the receiving water, the rotation of the Earth, and any ambient motion in the receiving water, such as tides or seiches.

If the river water has a higher density than the surface of the receiving water, the river water will plunge below the surface. The river water will then either form an underflow or an interflow within the lake. However, if the river water is lighter than the receiving water, as is typically the case when fresh river water flows into the sea, the river water will float along the surface of the receiving water as an overflow.

Substrate is the earthy material that forms or collects at the bottom of an aquatic habitat. It is made of sediments that may consist of:

• Silt – A loose, granular material with mineral particles 0.5 mm or less in diameter.
• Clay – A smooth, fine-grained material made of fine particles of hydrous aluminium phyllosilicate minerals (such as kaolinite).
• Mud – A mixture of water with silt, clay, or loam.
• Sand – Mineral particles between 0.06 and 2 mm in diameter.
• Granule – Between 2 and 4 mm in diameter.
• Pebble – Between 4 – 64 mm in diameter.
• Cobble – between 6.4 and 25.6 cm in diameter
• Boulder – more than 25.6 cm in diameter.
• Other, assorted organic matter, detritus.

Stream substrate can affect the life found within the stream habitat. Muddy streams generally have more sediment in the water, reducing clarity. Clarity is one guide to stream health.

Alluvium (from Latin alluvius, from alluere 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is typically geologically young and is not consolidated into solid rock. Sediments deposited underwater, in seas, estuaries, lakes, or ponds, are not described as alluvium.Floodplain alluvium can be highly fertile, and supported some of the earliest human civilizations.

A tidal strait is a strait through which a tidal current flows. Tidal currents are usually unidirectional but sometimes are bidirectional. Tidal straits, though they are narrow seaways, are technically not rivers. They are frequently of tectonic origin. In them, currents develop because of elevation differences between the water basins at both ends. Tidal straits can connect seas and oceans, as well as estuarine zones.

Tides sometimes allow sediments to collect in tidal straits.

Rock magnetism is the study of the magnetic properties of rocks, sediments and soils. The field arose out of the need in paleomagnetism to understand how rocks record the Earth's magnetic field. This remanence is carried by minerals, particularly certain strongly magnetic minerals like magnetite (the main source of magnetism in lodestone). An understanding of remanence helps paleomagnetists to develop methods for measuring the ancient magnetic field and correct for effects like sediment compaction and metamorphism. Rock magnetic methods are used to get a more detailed picture of the source of the distinctive striped pattern in marine magnetic anomalies that provides important information on plate tectonics. They are also used to interpret terrestrial magnetic anomalies in magnetic surveys as well as the strong crustal magnetism on Mars.

Strongly magnetic minerals have properties that depend on the size, shape, defect structure and concentration of the minerals in a rock. Rock magnetism provides non-destructive methods for analyzing these minerals such as magnetic hysteresis measurements, temperature-dependent remanence measurements, Mössbauer spectroscopy, ferromagnetic resonance and so on. With such methods, rock magnetists can measure the effects of past climate change and human impacts on the mineralogy (see environmental magnetism). In sediments, a lot of the magnetic remanence is carried by minerals that were created by magnetotactic bacteria, so rock magnetists have made significant contributions to biomagnetism.

Badlands are a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded. They are characterized by steep slopes, minimal vegetation, lack of a substantial regolith, and high drainage density. Ravines, gullies, buttes, hoodoos and other such geologic forms are common in badlands.

Badlands are found on every continent except Antarctica, being most common where there are unconsolidated sediments. They are often difficult to navigate by foot, and are unsuitable for agriculture. Most are a result of natural processes, but destruction of vegetation by overgrazing or pollution can produce anthropogenic badlands.

In geology, a graded bed is a bed characterized by a systematic change in grain or clast size from bottom to top of the bed. Most commonly this takes the form of normal grading, with coarser sediments at the base, which grade upward into progressively finer ones. Such a bed is also described as fining upward. Normally graded beds generally represent depositional environments which decrease in transport energy (rate of flow) as time passes, but these beds can also form during rapid depositional events. They are perhaps best represented in turbidite strata, where they indicate a sudden strong current that deposits heavy, coarse sediments first, with finer ones following as the current weakens. They can also form in terrestrial stream deposits.

In reverse grading or inverse grading the bed coarsens upwards. This type of grading is relatively uncommon but is characteristic of sediments deposited by grain flow and debris flow. A favored explanation for reverse grading in these processes is kinetic sieving. It is also observed in aeolian processes, such as in pyroclastic fall deposits. These deposition processes are examples of granular convection.

In geology, consolidation is used in several senses:

• Lithification, the overall process of conversion of loose sediments to solid rock.
• Any other process in which loose or fluid material becomes solid rock, such as solidification of magma.
• Compaction (geology), the decrease in volume and increase in density of sediments as the weight of overlying sediments increases, mineral grains move to more compact arrangements, and pore water is expelled. The term is particularly used for soil consolidation.
• Rarely, as a term for the conversion of a mobile belt to a rigid part of a continental platform; an orogeny.

An isopach map (/ˈaɪsoʊpæk/) illustrates thickness variations within a tabular unit, layer or stratum. Isopachs are contour lines of equal thickness over an area. Isopach maps are utilized in hydrographic survey, stratigraphy, sedimentology, structural geology, petroleum geology and volcanology.

An isopach map is similar to an isochore map, but these terms actually describe different methods of displaying thickness variations within a layer.