I'm kinda curious what A has to do with B.
A lot of the Appalachians was eroded and went into the Gulf of Mexico and the Atlantic before man probably walked on two legs. Conventional drilling is accessing depths in the Appalachians that aren't touched in other areas of the US simply because of lot of the higher layers were gone long before us. Now we've learned that there's oil and gas at much deeper depths in the Appalachians.
If that holds true for the Appalachians, what about other areas?