I thought the Himalayas were the result of a subduction between the Indian subcontinent and the Asian mainland. Are the Tetons a similar subduction range?
Generally similar but older from what I read. The difference would be that the Indian plate was a long ways off and unrelated to the Eurasian plate. However mountain building is similar.
Sounds like long before this particular range formed, once upon a time a different range formed from continental collisions that created those old rocks. The current orogeny exposed those older rocks.