> As oil it was trapped under shale or in sands where it had no effect on the water table and didn't get into the water or food supply. In many places we knew

> As oil it was trapped under shale or in sands where it had no effect on the water table and didn't get into the water or food supply. In many places we knew oil was there because it was leaking out. Some of the deposits were exposed to the surface. We have ancient records of people making use of it to make adhesive or caulk boats. Those have just tended to have gotten used up by now.