The oldest mountain range on the planet.

[dlamberth]

I know this has been brought up before, but I think it's pretty cool so here it is again. That the Scottish Highlands, the Appalachians, and the Atlas are the same mountain range, once connected as the Central Pangean Mountains. The Central Pangean Mountains were formed as a result of the collusion of Laurissia and Gondwana. At it's greatest elevation is was comparable to the Himalayas.

Here's a Wiki page: Central Pangean Mountains - Wikipedia