Sediment and Sedimentation - Key terms



BED LOAD:

Sediment that is capable of being transported by an erosive medium (wind, water, or air) but only under conditions in which it remains in nearly constant contact with the substrate or bottom (e.g., a streambed or the ground). Bedload, along with dissolved load and suspended load, is one of three types of sediment load.

COMPOUND:

A substance made up of atoms of more than one element chemically bonded to one another.

CONSOLIDATION:

A process whereby materials become compacted, or experience an increase in density. This takes place through a number of processes, including recrystallization and cementation.

DEPOSITION:

The process wherebysediment is laid down on the Earth's surface.

DIAGENESIS:

A term referring to all the changes experienced by a sediment sample under conditions of low temperature and low pressure following deposition.

DISSOLVED LOAD:

Sediment load that is absorbed completely by the erosive medium (either water or ice) that carries it. Dissolved load is one of three types of sediment load, the others being suspended load and bed load.

EROSION:

The movement of soil and rock due to forces produced by water, wind, glaciers, gravity, and other influences. In most cases, a fluid medium, such as air or water, is involved.

FLUID:

In the physical sciences, the term fluid refers to any substance that flows and therefore has no definite shape—that is, both liquids and gases. Occasionally, substances that appear to be solid (for example, ice in glaciers), in fact, are flowing slowly; therefore, within the earth sciences, ice often is treated as another fluid medium.

ION:

An atom or group of atoms that has lost or gained one or more electrons and thus has a net electric charge. Positively charged ions are called cations, and negatively charged ones are called anions.

MASS WASTING:

The transfer of earth material down slopes by processes that include creep, slump, slide, flow, and fall. Also known as mass movement.

MINERAL:

A naturally occurring, typically inorganic substance with a specific chemical composition and a crystalline structure.

ORGANIC:

At one time, chemists used the term organic only in reference to living things. Now the word is applied to most compounds containing carbon, with the exception of carbonates (which are minerals) and oxides, such as carbon dioxide.

PRECIPITATION:

In the context of chemistry, precipitation refers to the formation of a solid from a liquid.

REGOLITH:

A general term describing a layer of weathered material that rests atopbedrock.

ROCK:

An aggregate of minerals or organic matter, which may be consolidated or unconsolidated.

SEDIMENT:

Material deposited at or near Earth's surface from a number of sources, most notably preexisting rock. There are three types of sediment: rocks, or clastic sediment; mineral deposits, or chemical sediment; and organic sediment, composed primarily of organic material.

SEDIMENTARY ROCK:

One of the three major types of rock, along with igneous and metamorphic rock. Sedimentary rock usually is formed by the deposition, compaction, and cementation of rock that has experienced weathering. It also may be formed as a result of chemical precipitation.

SEDIMENTATION:

The process of erosion, transport, and deposition undergone by sediment.

SEDIMENT LOAD:

A term for the particles transported by a flowing medium of erosion (wind, water, or ice). The types of sediment load are dissolved load, suspended load, and bed load.

SEDIMENTOLOGY:

The study and interpretation of sediments, including sedimentary processes and formations.

SUSPENDED LOAD:

Sediment that is suspended, or floating, in the erosive medium (wind, water, or ice). Suspended load is one of three types of sediment load, along with dissolved load and bed load.

TILL:

A general term for the sediments left by glaciers that lack any intervening layer of melted ice.

UNCONSOLIDATED ROCK:

Rock that appears in the form of loose particles, such as sand.

WEATHERING:

The breakdown of rocks and minerals at or near the surface of Earth due to physical, chemical, or biological processes.

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