Drilling through this aquiclude will allow the perched water to drain out and down to the regional water table. With consistent overdraft, water table lowers 2. Without pore space, the aquifer can never contain as much water as it stored previously. Geologists can calculate how much rock has been removed. Both igneous and sedimentary precursors.
Batholiths make up the core of mountains.
Stone Mountain, Georgia is a batholith. Flat, since magma was forced between rock layers. Volcano cone erodes faster, leaving neck standing above the general land surface. Devil's Tower, Wyoming. Useful for engineers.