Shale


Shale

Shale (also called mudstone) is a fine-grained sedimentary rock whose original constituents were clay minerals or muds. It is characterized by thin laminae [cite encyclopedia
title = shale
encyclopedia = Chambers Dictionary of Science and Technology
publisher = Chambers Harrap Publishers Ltd
date = 1999
] breaking with an irregular curving fracture, often splintery and usually parallel to the often-indistinguishable bedding plane. This property is called fissility. Non-fissile rocks of similar composition but made of particles smaller than 1/16 mm are described as mudstones. Rocks with similar particle sizes but with less clay and therefore grittier are siltstones. Shale is the most common sedimentary rock. [cite web
url=http://wps.prenhall.com/esm_lutgens_foundations_3/0,6540,354318-,00.html
title= Rocks: Materials of the Lithosphere - Summary
publisher=
accessdate=2007-07-31
]

Formation

The process in the rock cycle which forms shale is compaction. The fine particles that compose shale can remain in water long after the larger and denser particles of sand have deposited. Shales are typically deposited in very slow moving water and are often found in lake and lagoonal deposits, in river deltas, on floodplains and offshore of beach sands. They can also be deposited on the continental shelf, in relatively deep, quiet water.

'Black shales' are dark, as a result of being especially rich in unoxidized carbon. Common in some Paleozoic and Mesozoic strata, black shales were deposited in anoxic, reducing environments, such as in stagnant water columns.

Fossils, animal tracks/burrows and even raindrop impact craters are sometimes preserved on shale bedding surfaces. Shales may also contain concretions.

Shales that are subject to heat and pressure alter into a hard, fissile, metamorphic rock known as slate, which is often used in building construction.

ee also

* Bituminous shale
* Oil shale
* Burgess shale
* Barnett Shale
* Bearpaw Shale
* Wianamatta shale

Footnotes

References

* Blatt, Harvey and Robert J. Tracy, 1996, "Petrology: Igneous, Sedimentary and Metamorphic", 2nd ed., Freeman, ISBN 0-7167-2438-3


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  • Shalë — Shalë …   Wikipedia Español

  • Shale — Shale, n. [AS. scealy, scalu. See {Scalme}, and cf. {Shell}.] 1. A shell or husk; a cod or pod. The green shales of a bean. Chapman. [1913 Webster] 2. [G. shale.] (Geol.) A fine grained sedimentary rock of a thin, laminated, and often friable,… …   The Collaborative International Dictionary of English

  • Shale — Shale, v. t. To take off the shell or coat of; to shell. [1913 Webster] Life, in its upper grades, was bursting its shell, or was shaling off its husk. I. Taylor. [1913 Webster] …   The Collaborative International Dictionary of English

  • shale — [ʃeıl] n [U] [: Old English; Origin: scealu shell, scale ] a smooth soft rock which breaks easily into thin flat pieces …   Dictionary of contemporary English

  • shale — [ ʃeıl ] noun uncount a type of smooth dark rock that breaks into thin layers …   Usage of the words and phrases in modern English

  • shale — (n.) 1747, possibly a specialized use of M.E. schale shell, husk, pod (late 14c.), also fish scale, from O.E. scealu (see SHELL (Cf. shell)) in its base sense of thing that divides or separate, in reference to the way the rock breaks apart in… …   Etymology dictionary

  • shale — ► NOUN ▪ soft stratified sedimentary rock formed from consolidated mud or clay. DERIVATIVES shaly (also shaley) adjective. ORIGIN probably from German Schale …   English terms dictionary

  • shale — [shāl] n. [< ME, lit., shell < OE scealu, SHELL] a kind of fine grained, thinly bedded sedimentary rock formed largely by the hardening of clay: it splits easily into thin layers: cf. MUDSTONE …   English World dictionary

  • shale — shalelike, shaley, adj. /shayl/, n. a rock of fissile or laminated structure formed by the consolidation of clay or argillaceous material. [1740 50; orig. uncert.; cf. obs. shale to split (said of stone), to shell, deriv. of shale shell, husk, OE …   Universalium

  • Shale — A type of sedimentary rock found in the earth s crust composed chiefly of a combination of silt and clay. A great deal of the earth s usable fossil fuels are found in shale formations. There are many different types of shale, such as oil shale… …   Investment dictionary


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