At the risk of oversimplification, those scientists believe the layers of rock forming the Ozark Plateau were laid down between 300-480 million years ago, when the far-flung plateau was a marine ...

Bulletin 3: Geology of the Arkansas Paleozoic Area, with especial reference to Oil and Gas Possibilities. Carey Croneis Pp. xx + 457 + 45 plates. (Little Rock, Ark.: Arkansas Geological Survey, 1930.) ...