According to this geology.com article, technologies now being practiced in areas producing shale gas might be utilized in two Triassic "Newark Basins" on the North Carolina Piedmont, the Dan River Basin and the Deep River Basin. (I tried to copy and post the NC map shown in the linked article, but it didn't work. I also tried to find a suitable diagram of a graben basin, with no luck.)
Basically, the Newark Basins are a series of elongate graben basins that form during periods of crustal extension. When the brittle crust is stretched and broken, some sections of the crust will subside along normal (gravity) faults. These basins are related to the Triassic and Jurassic Periods when Pangea was being stretched in "preparation" of splitting to begin the growth of the Atlantic Ocean basin. Before the basins were connected and deep-enough for ocean water ingress, they existed as inland basins with lakes and swamps. Without through-flowing river systems, organic material preserved in the shales and silts of these swamps could generate natural gas and oil under certain conditions (there is already some oil (and maybe gas) production from Newark Basins in other states).