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Sill
SillA sill is a formation of igneous rock found in features such as mesas, hogbacks, and cuestas. Although sills can become exposed, sills are formed underground and are thus composed of plutonic igneous rocks . Sills are an intrusive rock formation. Intrusive formations such as dikes and sills are formed from magma that solidifies beneath the Earth's surface and then intrudes into the overlying host or country rock . Sills are distinguishable from the similarly formed dikes and dome forming laccoliths because sills are horizontal in orientation to the surface. Accordingly, sills are a horizontal intrusion. Sills are sheet-like or tabular because the magma intrusion moves or intrudes horizontally before solidifying. Sills are characterized as concordant intrusive contacts. Because sills are an intrusive rock formation in contact with the host or country rock in the horizontal plane, they are often parallel to foliation or bedding planes (e.g., parallel to underlying sedimentary bedding planes). Sills form as rising magma encounters vertical resistance from host rock. The upwelling magma then spreads out in the horizontal plane into area of lower resistance to form sheet-like layers of rock. Sill texture is a function of the time it takes for the magma to cool and solidify. Sills range from aphanitic to phaneritic in texture. In general, the longer the time to cool, the greater the extent and size of crystal formation. If a sill cools quickly, the texture is usually smooth and mineral crystals are not visible to the naked eye (aphanitic in texture). If conditions in the surrounding host rock are such that the magma cools over a long period of time, large visible crystals form a phaneritic texture. When sills come to overlie sedimentary basins, the sills can act as horizontal obstructions that cap traps or reservoirs containing hydrocarbon fuels . See also Dike; Petroleum detection; Pluton and plutonic bodies; Stratigraphy |
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"Sill." World of Earth Science. 2003. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "Sill." World of Earth Science. 2003. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1G2-3437800554.html "Sill." World of Earth Science. 2003. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3437800554.html |
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sill
sill / sil/ • n. a shelf or slab of stone, wood, or metal at the foot of a window or doorway. ∎ a strong horizontal member at the base of any structure, e.g., in the frame of a motor or rail vehicle. ∎ Geol. a tabular sheet of igneous rock intruded between and parallel with the existing strata. Compare with dike1 . ∎ an underwater ridge or rock ledge extending across the bed of a body of water. ORIGIN: Old English syll, sylle ‘horizontal beam forming a foundation,’ of Germanic origin; related to German Schwelle ‘threshold.’ |
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"sill." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "sill." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O999-sill.html "sill." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-sill.html |
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sill
sill beam forming the foundation of a wall OE.; lower horizontal part of a window opening XV; threshold XVI. OE. syll(e) = MLG. sul(le), MDu. sulle, rel. to MLG., MDu. sille, ON. svill, syll, and MHG. swelle, OHG. swelli, swella (G. schwelle threshold), Goth. gasuljan found, establish, sulja sole.
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T. F. HOAD. "sill." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. T. F. HOAD. "sill." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O27-sill.html T. F. HOAD. "sill." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-sill.html |
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sill
sill Sheet-like intrusion of igneous rock that is parallel to the bedding or other structure of the surrounding rock. Sill rock is normally medium-grained; basic sills (dolerites) are the commonest.
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"sill." World Encyclopedia. 2005. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "sill." World Encyclopedia. 2005. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O142-sill.html "sill." World Encyclopedia. 2005. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-sill.html |
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sill
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AILSA ALLABY and MICHAEL ALLABY. "sill." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "sill." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-sill.html AILSA ALLABY and MICHAEL ALLABY. "sill." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-sill.html |
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sill
sill. See cill.
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JAMES STEVENS CURL. "sill." A Dictionary of Architecture and Landscape Architecture. 2000. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. JAMES STEVENS CURL. "sill." A Dictionary of Architecture and Landscape Architecture. 2000. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O1-sill.html JAMES STEVENS CURL. "sill." A Dictionary of Architecture and Landscape Architecture. 2000. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O1-sill.html |
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sill
sill
•bill, Brazil, brill, Camille, chill, cookchill, dill, distil (US distill), downhill, drill, Edgehill, Estoril, fill, freewill, frill, fulfil (US fulfill), Gill, goodwill, grill, grille, hill, ill, instil, kill, krill, mil, mill, nil, Phil, pill, quadrille, quill, rill, Seville, shill, shrill, sill, skill, spadille, spill, squill, still, stock-still, swill, thill, thrill, till, trill, twill, until, uphill, will
•hwyl • bank bill • handbill • waxbill
•playbill, waybill
•cranesbill • sibyl • crossbill • sawbill
•hornbill • storksbill • shoebill
•spoonbill • duckbill • razorbill
•gerbil • wind chill • Churchill • idyll
•daffodil • back-fill • landfill • monofil
•fibrefill (US fiberfill) • chlorophyll
•bluegill
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"sill." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "sill." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O233-sill.html "sill." Oxford Dictionary of Rhymes. 2007. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-sill.html |
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