== == This layer is called bedrock.
The bedrock is a solid rock layer beneath loose deposits such as soil.
When you dig up dirt you get to this hard soil like substance. Beneath this is the hard rock you're talking about. It is called Bedrock.
This layer of solid rock is called bedrock.
Solid unweathered rock lying beneath surface deposits of soil.
Bedrock is the usual term
The layer of solid rock just below the soil is the bedrock of the ground.
The second layer
It is a layer of hard solid rock nothing else in it.
Hard pans, and/or bedrocks.