Bedrock is the hard compacted material that underlies everywhere and you can think of it as the uppermost crust of the earth. There's places where the bedrock is right at the surface. Places like Iowa where we're relatively flat we've also had glaciers come over us so those glaciers left behind soft sediments like soil sand gravel things like that. In the state of Iowa we have places where there's over 600 feet of that unconsolidated glacial sediment before you even get to the bedrock. If you go to Northeast Iowa it's right there at you know right at the surface. So bedrock is different in different places but it is essentially the hard compacted material that underlies everywhere.

Gilchrist Foundation