In geology, bedrock is solid rock that lies under loose material (regolith) within the crust of Earth or another terrestrial planet.
In that day their strong cities, which they left because of the Israelites, will be like places abandoned to thickets and undergrowth. And all will be desolation. Isaiah 17:9 NIV
The various kinds of broken and weathered rock material, such as soil and subsoil, that may overlie the bedrock are known as regolith.