[GH85Carrera]

Oklahoma has some of the oldest mountains in the United States, the western Arbuckle Mountains has a core comprised of Precambrian granite and gneiss that is 1.3 billion years old. These Precambrian rocks are overlain by Cambrian rhyolite that is 525 million years old. During the Late Cambrian through the Pennsylvanian, 515 to 290 million years ago, respectively, seas encroached and then retreated, leaving deposits of limestone, dolomite, sandstone, and shale covering the mountains.