How did the rock of the Great Plains and Rocky Mountains form? Choose the claim to eliminate *

Claim 1: They formed as one rock formation, and then something separated them.

Claim 2: One rock formation formed before the other. Then, the minerals from the older rock became part of the younger rock

Claim 2 has to be eliminated

The young rock (mountain) becomes old.

Explanation:

All the mountains of the world are either young (high mountains such as the Himalaya) or old (low mountains such as the Pyrenees mountains). The latter is a low mountain range because time has had its erosive effect.

There is no such thing as minerals going from one rock or mountain to the other because there is only one. And it's young or (becomes) old.