"How old the Appalachian Mountains really are:

They are older than trees, bones (including all dinosaurs), and the splitting of Pangaea -- so part of the mountain range is in Scotland.

The layering on the mountains looks "wrong" at some points because the tops of the mountains have eroded down & "new" geological forces have caused parts that weren't the top to rise above that...so the valleys of the current mountains may actually be the top of the original Appalachian Mountains."