Bedrock
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In geology, bedrock is solid rock that lies under loose material (regolith) within the crust of Earth or another terrestrial planet.
DefinitionEdit
Bedrock is the solid rock that underlies looser surface material.<ref>Template:Cite book</ref> An exposed portion of bedrock is often called an outcrop.Template:Sfn The various kinds of broken and weathered rock material, such as soil and subsoil, that may overlie the bedrock are known as regolith.Template:Sfn<ref>Template:Cite book</ref>
Engineering geologyEdit
The surface of the bedrock beneath the soil cover (regolith) is also known as rockhead in engineering geology,<ref>Template:Cite book</ref><ref name="Gribble&McLean">Template:Cite book</ref> and its identification by digging, drilling or geophysical methods is an important task in most civil engineering projects. Superficial deposits can be very thick, such that the bedrock lies hundreds of meters below the surface.<ref>Template:Cite magazine</ref>
Weathering of bedrockEdit
Exposed bedrock experiences weathering, which may be physical or chemical, and which alters the structure of the rock to leave it susceptible to erosion. Bedrock may also experience subsurface weathering at its upper boundary, forming saprolite.<ref name="siv">Template:Cite journal</ref> Rock fragments can disconnect from the underlying bedrock, where they are found within a weathering or soil profile as floaters.<ref name=uky>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Geological mapEdit
A geological 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. Where superficial deposits are so thick that the underlying bedrock cannot be reliably mapped, the superficial deposits will be mapped instead (for example, as alluvium).<ref name="BGS">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>