The Point Pleasant-Brassfield(!) petroleum system, located in eastern Ohio and western parts of Pennsylvania and West Virginia, created a charge of 150 billion bbl of oil equivalent. The system covers 40,000 km² and encompasses numerous small oil and gas fields in eastern Ohio. Sedimentary rocks included in this system are Ordovician-Triassic in age and were deposited in the Appalachian basin. Several source rocks exist within the basin, including shales of the Ordvocian Point Pleasant Formation, the Devonian Ohio Shale and Olentangy Shale, and the Mississippian Sunbury Shale. Most of the oil in the Silurian Clinton reservoir rock (Brassfield Formation) originated from the Point Pleasant Formation. Oil generated from the Point Pleasant source rock has chemical haracteristics similar to early Paleozoic oils. Based on paraffin indices, oil from this source rock is very mature to supermature and has lost most biological markers.

Generation-migration-accumulation lasted from Point Pleasant deposition in Middle Ordovician time through maximum deposition in the Late Triassic-Early Jurassic, a duration of about 250 m.y. The mass of hydrocarbons generated by the source rock in the Point Pleasant Formation totaled 75 billion bbl of oil. Of this, some found its way to traps with Silurian reservoir rocks on the east flank of the Cincinnati-Findlay arch. Only 400 million bbl of in-place oil can be accounted for in known fields. The remaining oil and gas generated by the Point Pleasant source rock was probably lost in subeconomic accumulations along the migration pathway between the pod of active source rock and the geographic extent of the Point Pleasant-Brassfield petroleum system.