Encyclopedia > Shale

  Article Content

Shale

Shale is a fine-grained sedimentary rock whose original constituents were clays or muds[?]. It is characterized by thin laminae breaking with an irregular curving fracture, often splintery, and parallel to the often indistinguishable bedding planes. Non-fissile rocks of similar composition but made of particles smaller than 1/16 mm are mudstones. Rocks with similar particle sizes but with less clay and therefore grittier are siltstones.

The fine particles that compose shale can remain suspended in water long after the larger and denser particles of sand have deposited out. 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.

Fossils, animal tracks/burrows, and even raindrop impact craters are sometimes preserved on shale bedding surfaces. Shales that are subject to heat and pressure alter into a hard fissile material known as slate that is often used in building construction.

See also: oil shale, Burgess shale, List of minerals



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Xenobiology

... a future technology. It might be difficult to tell whether a truly strange life form had in fact arisen in space, or was designed much nearer to home. Although this is ...