Bedrock can be made of igneous, metamorphic or sedimentary rock, but all bedrock is consolidated by aggregate pressure from above showing up beneath gravel, soil, sand and ocean sediments. Any type of rock can turn into bedrock over time as other materials develop on top of it.
Bedrock extends hundreds of meters beneath the Earth's surface, at times nearing the base of the crust. The beginning point of bedrock is the rockhead. In some areas, weathering has worn away the overlying layers, exposing bedrock in quarries, on top of some mountains, along coastlines and on top of plateaus. Called outcroppings, these areas give geologists clues about the earlier travel paths of glaciers and other ancient events in geological history.