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petrology
(Encyclopedia) petrology, branch of geology specifically concerned with the origin, composition, structure, and properties of rocks, primarily igneous and metamorphic, and secondarily sedimentary. It…waterfall
(Encyclopedia) waterfall, a sudden unsupported drop in a stream. It is formed when the stream course is interrupted as when a stream passes over a layer of harder rock—often igneous—to an area of…pumice
(Encyclopedia) pumicepumicepŭmˈĭs [key], volcanic glass formed by the solidification of lava that is permeated with gas bubbles. Usually found at the surface of a lava flow, it is colorless or light…topaz
(Encyclopedia) topaztopaztōˈpăz [key], aluminum silicate mineral with either hydroxyl radicals or fluorine, Al2SiO4(F,OH)2, used as a gem. It is commonly colorless or some shade of pale yellow to…batholith
(Encyclopedia) batholith, enormous mass of intrusive igneous rock, that is, rock made of once-molten material that has solidified below the earth's surface (see rock). Batholiths usually are granitic…The Nature of Volcanoes
Volcanoes are built by the accumulation of their own eruptive products—lava, bombs (crusted over ash flows), and tephra (airborne ash and dust). A volcano is most commonly a conical hill or mountain…Brewer's: Plutonic Rocks
Granites, and certain porphyries, supposed to be of igneous, but not of volcanic, origin. So called by Lyell from Pluto, the principle of elemental fire. Source: Dictionary of Phrase and…Brewer's: Vulcanist
One who supports the Vulcanian or Plutonian theory, which ascribes the changes on the earth's surface to the agency of fire. These theorists say the earth was once in a state of igneous…continent
(Encyclopedia) continent, largest unit of landmasses on the earth. The continents include Eurasia (conventionally regarded as two continents, Europe and Asia), Africa, North America, South America,…serpentine
(Encyclopedia) serpentineserpentinesûrˈpəntēn, –tīn [key], hydrous silicate of magnesium. It occurs in crystalline form only as a pseudomorph having the form of some other mineral and is generally…Trending
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