![]() Slates may be black, blue, purple, red, green, or gray. The direction of cleavage depends upon the direction of the stresses applied during metamorphism. On this account, slates occur chiefly among older rocks, although some occur in regions in which comparatively recent rocks have been folded and compressed as a result of mountain-building movements. Cleavage is a super-induced structure, the result of pressure acting on the rock at some time when it was deeply buried beneath the Earth’s surface. The parent rock may be only partially altered so that some of the original mineralogy and sedimentary bedding are preserved the bedding of the sediment as originally laid down may be indicated by alternating bands, sometimes seen on the cleavage faces. The original material was a fine clay, sometimes with sand or volcanic dust, usually in the form of a sedimentary rock ( e.g., a mudstone or shale). Slate was formed under low-grade metamorphic conditions- i.e., under relatively low temperature and pressure. True slates do not, as a rule, split along the bedding plane but along planes of cleavage, which may intersect the bedding plane at high angles. Slate, fine-grained, clayey metamorphic rock that cleaves, or splits, readily into thin slabs having great tensile strength and durability some other rocks that occur in thin beds are improperly called slate because they can be used for roofing and similar purposes. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians. Slate definition how to#COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives. ![]()
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