In geology, the term clastic refers to sediments formed from fragments of pre-existing rock. Clastic sedimentary rocks are rocks composed predominately of broken pieces or 'clasts' of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on grain size, clast and cementing material (matrix) composition, and texture. The classification factors are often useful in determining a sample's environment of deposition. Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ... Sedimentary, volcanic, plutonic, metamorphic rock types of North America. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... Weathering is the process of decomposition and/or disintegration of rocks in situ, that is, in place. ... Look up Erosion on Wiktionary, the free dictionary Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case... This article deals with grain size in the context of geology, see crystallite for grain size in materials science. ... In geology, if a rock consists of larger crystals (phenocrysts) embedded in fine grained often microscopic crystals, this surrounding material (or substrate) is termed matrix. ...

Grain size varies from clay in shales; through silt in siltstones; sand in sandstones; and gravel, cobble, to boulder sized fragments in conglomerates and breccias. The Krumbein phi (φ) scale numerically orders these terms in a logarithmic size scale. Clay is a generic term for an aggregate of hydrous silicate particles less than 4 μm (micrometres) in diameter. ... Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Silt refers to soil or rock particles of a certain very small size range (see grain size). ... Categories: Stub | Sedimentary rocks ... Patterns in the sand Sand is an example of a class of materials called granular matter. ... Red Sandstone in Wyoming Sandstone is an arenaceous sedimentary rock composed mainly of feldspar and quartz and varies in colour (in a similar way to sand), through grey, yellow, red, and white. ... Gravel being unloaded from a barge Gravel is rock that is of a certain size range. ... Cobble is a geologic term for a rock or rock fragment with a grain size with dimensions between 64–256 mm (2. ... This article is about the large rocks known as boulders. ... A mineral conglomerate In geology, a conglomerate is a rock consisting of other stones that have been cemented together. ... Breccia, derived from the Latin word for broken, is a sedimentary rock composed of angular fragments in a matrix that may be of a similar or a different material. ... This article deals with grain size in the context of geology, see crystallite for grain size in materials science. ...

Composition includes the chemical and mineralogic make-up of the single or varied fragments and the cementing material (matrix) holding the clasts together as a rock. A chemical substance is any material substance used in or obtained by a process in chemistry: A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions. ... This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ... In geology, if a rock consists of larger crystals (phenocrysts) embedded in fine grained often microscopic crystals, this surrounding material (or substrate) is termed matrix. ...

Texture refers to the particle shape and the amount of sorting of the grains that compose a rock or sediment sample. Sorting can be expressed mathematically by the standard deviation of the grain-size frequency curve of a sediment sample, expressed as values of φ (phi). Values range from <0.35φ (very well sorted) to >4.00φ (extremely poorly sorted). Particle shape includes form, rounding, and surface texture. Form indicates whether a grain is more equant (round, spherical) or platy (flat, disc-like, oblate); as well as sphericity. Roundness refers to the degree of sharpness of the corners and edges of a grain. The surface texture of grains may be polished, frosted, or marked by small pits and scratches.

An example clastic environment would be a river system, in which the full range of grains being transported by the moving water consist of pieces eroded from solid rock upstream. Look up Erosion on Wiktionary, the free dictionary Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case...