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

In stratigraphy, bedrock is the common term for solid rock under the surface of the Earth. Above the bedrock is usually an area of broken and weathered rock, soil, sand, pebbles, etc.

The top of the bedrock is known as the rockhead and identifying this, via excavations, drilling or geophysical methods, is an important task in most civil engineering projects. Loose material on top (known as drift) can be extremely thick, so that the bedrock lies hundreds of meters below the surface.