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{{Short description|Lithified rock under the regolith}} |
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{{Redirect|Subsurface}} |
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[[File:Rockhead at Sandside Bay, Caithness, Scotland.jpg|thumb|upright|Soil with broken rock fragments overlying bedrock, Sandside Bay, [[Caithness]]]] |
[[File:Rockhead at Sandside Bay, Caithness, Scotland.jpg|thumb|upright|Soil with broken rock fragments overlying bedrock, Sandside Bay, [[Caithness]]]] |
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'''Bedrock''' in [[geology]] is the [[Lithification|lithified]] [[Rock (geology)|rock]] that lies under loose softer material called [[regolith]] within the surface of the [[Earth]]'s crust or other [[terrestrial planet]]s. |
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== Components of bedrock == |
== Components of bedrock == |
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Bedrock essentially refers to the substructure composed of hard rock exposed or buried at the earth's surface; an exposed portion of bedrock is often called an [[outcrop]]. Bedrock may have various chemical and mineralogical compositions and can be [[Igneous rock|igneous]], [[Metamorphic rock|metamorphic]] or [[Sedimentary rock|sedimentary]] in origin. The bedrock may be overlain by broken and weathered [[regolith]] which includes [[soil]] and the [[subsoil]].{{Citation needed|date=April 2019}} |
Bedrock essentially refers to the substructure composed of hard rock exposed or buried at the earth's surface; an exposed portion of bedrock is often called an [[outcrop]]. Bedrock may have various chemical and mineralogical compositions and can be [[Igneous rock|igneous]], [[Metamorphic rock|metamorphic]] or [[Sedimentary rock|sedimentary]] in origin. The bedrock may be overlain by broken and weathered [[regolith]] which includes [[soil]] and the [[subsoil]].{{Citation needed|date=April 2019}} |
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== Engineering geology == |
== Engineering geology == |
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⚫ | The surface of the bedrock beneath the soil cover (regolith) is also known as '''rockhead''' in [[engineering geology]],<ref>Price, David George, ''Engineering Geology: Principles and Practice,'' Springer, 2009, p.{{nbsp}}16 {{ISBN|978-3540292494}}</ref><ref name="Gribble&McLean">{{cite book | url=https://books.google.com/?id=ayPapNgD1hMC&pg=PA113&dq=bedrock+contour+map+rockhead#v=onepage&q=bedrock%20contour%20map%20rockhead&f=false | title=Geology for Civil Engineers | publisher=CRC Press | author=Gribble C. & McLean A. | year=2003 | page=113 | isbn=978-0-203-36215-0}}</ref> and its identification by digging, drilling or [[geophysics|geophysical]] methods is an important task in most [[civil engineering]] projects. Superficial [[deposit (geology)|deposits]] (also known as [[drift (geology)|drift]]) can be extremely thick, such that the bedrock lies hundreds of meters below the surface.<ref>{{cite web|url=http://www.dnr.state.oh.us/Portals/10/pdf/newsletter/2004No.1.pdf |title=Swinford, E. Mac What the glaciers left behind – drift thickness map of Ohio, Ohio Department of Natural Resources, Division of Geological Survey, newsletter 2004, No.1. |date= |accessdate=12 September 2012 |deadurl=yes |archiveurl=https://web.archive.org/web/20121002225931/http://www.dnr.state.oh.us/Portals/10/pdf/newsletter/2004No.1.pdf |archivedate=2 October 2012 |df= }}</ref> |
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⚫ | The surface of the bedrock beneath the soil cover (regolith) is also known as '''rockhead''' in [[engineering geology]],<ref>Price, David George, ''Engineering Geology: Principles and Practice,'' Springer, 2009, p.{{nbsp}}16 {{ISBN|978-3540292494}}</ref><ref name="Gribble&McLean">{{cite book | url=https://books.google.com/ |
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== Weathering of bedrock == |
== Weathering of bedrock == |
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⚫ | Bedrock when exposed or within the subsurface may experience [[weathering]] and erosion by external factors. Weathering may be physical or chemical and alters the structure of the rock and may cause it to erode and or alter over time based on the interactions between the mineralogy and its interactions. Bedrock may also experience subsurface weathering at its upper boundary, forming [[saprolite]].<ref name=siv>{{cite journal|title=Palaeosurfaces and associated saprolites in southern Sweden|journal=Geological Society, London, Special Publications|author1=Lidmar-Bergström, Karna|author2=Olsson, Siv|author3=Olvmo, Mats|authorlink1=Karna Lidmar-Bergström|year=1997|volume=120|page=95|doi=10.1144/GSL.SP.1997.120.01.07|url=http://sp.lyellcollection.org/cgi/content/abstract/120/1/95|accessdate=April 21, 2010|issue=1|bibcode=1997GSLSP.120...95L}}</ref> |
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⚫ | Bedrock when exposed or |
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⚫ | A [[geologic map]] of an area will usually show the distribution of differing bedrock types, rock that would be exposed at the surface if all [[soil]] or other superficial deposits were removed.<ref name="BGS">{{cite web|url=http://www.bgs.ac.uk/products/digitalmaps/digmapgb_solid.html|title=Digital Geology – Bedrock geology theme|last=BGS|accessdate=12 November 2009| archiveurl=https://web.archive.org/web/20091213185511/http://www.bgs.ac.uk/products/digitalmaps/digmapgb_solid.html| archivedate= 13 December 2009 | deadurl= no}}</ref> |
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⚫ | A [[geologic map]] of an area will usually show the distribution of differing bedrock types, rock that would be exposed at the surface if all [[soil]] or other superficial deposits were removed.<ref name="BGS">{{cite web|url=http://www.bgs.ac.uk/products/digitalmaps/digmapgb_solid.html|title=Digital Geology – Bedrock geology theme|last=BGS|accessdate= |
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== See also == |
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* {{annotated link|Geology}} |
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* {{annotated link|Outcrop}} |
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* {{annotated link|Regolith}} |
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* {{annotated link|Soil}} |
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* {{annotated link|Weathering}} |
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== References == |
== References == |
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{{Reflist}} |
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== Further reading == |
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{{Commons category}} |
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== External links == |
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* {{commonscat-inline|Bedrock}} |
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[[Category:Geology]] |
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[[Category:Petrology]] |
[[Category:Petrology]] |
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[[Category:Rocks]] |
[[Category:Rocks]] |
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{{Geology-stub}} |