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Soil with broken rock fragments overlying bedrock, Sandside Bay, Caithness.

In stratigraphy, 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.^[1]

A solid geologic map of an area will usually show the distribution of differing rock types; i.e., rock that would be exposed at the surface if all soil or other superficial deposits were removed.^[2]

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