Bedrock

Bedrock

Bedrock is the native "consolidated" rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered "unconsolidated" rock in the basal subsoil. The top of the bedrock is known as "rockhead" and identifying this, via excavations, drilling or geophysical methods, is an important task in most Civil engineering projects. Superficial deposits (also known as drift) can be extremely thick such that the bedrock lies hundreds of metres below the surface [ [http://www.dnr.state.oh.us/Portals/10/pdf/newsletter/2004No.1.pdf 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.] ] .

A "solid" geologic map of an area will usually show bands of differing rock type; i.e., rock that would be exposed at the surface if all soil or other superficial deposits were removed. The different rock strata or layers that are indicated may be a result of either nonparallel (sloping) surface erosion at the edges of flat strata "or" normal surface erosion of tilted strata that has removed the upper portions of higher layers.

References

ee also

*Geology
*Igneous rock
*Metamorphic rock
*Rock (geology)
*Sedimentary rock
*Stratigraphy
*Topography

[sv:Berggrund]


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