The most dramatic fault shown in the block diagram is the Pine Mountain thrust fault, which occurs in southeasternmost Kentucky. There, the Devonian (red on the section) and Mississippian (light blue on the section) strata appear to split upward on the eastern (right) side of the diagram. Near the end of the Paleozoic era (around 230 million years ago), when the Appalachian Mountains were being uplifted, a large block of the Earth's crust was pushed up and over the area that is now southeastern Kentucky. The pressures from mountain building caused the northeast edge of a block of Devonian, Mississippian, and Pennsylvanian strata to be pushed upward, forming a 125-mile long ridge that we call Pine Mountain.