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The planet we live on: The beginnings of the Earth Sciences

The planet we live on: The beginnings of the Earth Sciences

The planet we live on: The beginnings of the Earth Sciences

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GlossaryAbsolute age <str<strong>on</strong>g>The</str<strong>on</strong>g> age <strong>of</strong> a rock or an event in years, or milli<strong>on</strong>s <strong>of</strong> yearsAcid mine drainage When mines are working, <strong>the</strong> water table is <strong>of</strong>ten lo<str<strong>on</strong>g>we</str<strong>on</strong>g>red, allowingminerals to oxidise; when <strong>the</strong> mine is aband<strong>on</strong>ed, <strong>the</strong> water rises and dissolves <strong>the</strong>minerals, producing acid, which drains from old mine passages into surroundingstreamsAcid rain Rain polluted by human-produced chemicals in <strong>the</strong> atmosphere, such as nitrogenand sulfur compounds, in additi<strong>on</strong> to <strong>the</strong> normal carb<strong>on</strong> dioxide c<strong>on</strong>tent <strong>of</strong><strong>the</strong> rainAcid test One drop <strong>of</strong> dilute hydrochloric acid (<str<strong>on</strong>g>we</str<strong>on</strong>g>ar eye protecti<strong>on</strong>) is added to <strong>the</strong>specimen; if it reacts (fizzes), carb<strong>on</strong>ate is present, usually calcium carb<strong>on</strong>ate; usedto identify calcite, arag<strong>on</strong>ite, limest<strong>on</strong>e and marbleAggregate Crushed rock (e.g. limest<strong>on</strong>e, sandst<strong>on</strong>e, granite, basalt) or sand and gravel;used to add to c<strong>on</strong>crete, for foundati<strong>on</strong>s and for railwaysAndesite A fine-grained chemically intermediate igneous rock found in lavas and smallintrusi<strong>on</strong>s; usually grey in colourAngular unc<strong>on</strong>formity Unc<strong>on</strong>formity, where <strong>the</strong> rocks beneath <strong>the</strong> unc<strong>on</strong>formity surfacedip at a different (usually steeper) angle than <strong>the</strong> rocks aboveAnomaly A feature (e.g. high copper c<strong>on</strong>centrati<strong>on</strong>; high magnetic field strength) thatdiffers from <strong>the</strong> backgroundAnticline Upfolded rocks (strictly, folded rocks with <strong>the</strong> oldest rock in <strong>the</strong> centre <strong>of</strong> <strong>the</strong>fold - since, if <strong>the</strong> sequence was tect<strong>on</strong>ically inverted, anticlines would be downfolds)Aquifer A permeable rock layer c<strong>on</strong>taining waterArag<strong>on</strong>ite A mineral (CaCO 3 ); an allotrope <strong>of</strong> calcite (same chemical make-up, differentatomic structure)Archaea Simple organisms that have cells with no nucleiAsteroids Small bodies in outer space that sometimes collide with <str<strong>on</strong>g>planet</str<strong>on</strong>g>s150

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