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 term implies that the rock lies in beds, or strata. Under any given location on the surface of the planet, rock will be found. The term bedrock may be somewhat misleading, since in many locations, the bedrock may change over a short distance, or the technical bedrock may be a thin stratum overlying quite different rock. A geologic map of an area will usually show bands of differing rock type exposure, i.e., rock that would be exposed at the surface if all soil 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.
