What does it mean if your ex boyfriend still wears the chain you brought him?
This could indicate that he still has feelings for you, or simply, he really likes the chain. If you think he still likes you, talk to him about it, or if you are afraid to, ask your friends or his friends if they think that he still likes you.
In general, the younger the mountain chain, the taller it is. Plate tectonics builds mountains by thrusting the crust upward, while erosion wears them back down over millenia. So the Himalayas are a new (and in fact, still growing) mountain chain, while the Appalachians are one of the oldest chains still identifiable as mountains.