The state of Pennsylvania is crossed diagonally by the Appalachian Mountains and the Appalachian Plateau. This mountains have a long history, the rocks are folded several times, so the geological structure is very complicated. The state has several caves but the complicated geology prevented really extraordinary caves. On the other hand there are numerous valuable deposits, most important are the anthracite coal fields at the eastern border of the state. There are numerous show mines all over the state.