The Appalachian mountains are extremely old, in fact they formed back when the contents were one big content, pangea. They span both the USA and Europe since they formed when they were one. They predate dinosaurs, humans, and even the very first animal.
@kilroy_was_here hahah i mean the rockies are extraordinary in terms of the animals and views there for sure.. I am still amazed by my experiences there... But historically speaking far less impressive :)