I understand that it is a level 70 zone and therefore they put level 70 gathering nodes there. But story-wise it makes no sense. The Lore of WoW is rich and entertaining and is one of the best parts of playing this game. Inconsistencies like this mar the immersion of what is otherwise a very fun new zone.
Lasica responded to Battery's question about this on the forums with a suggestion that they fell out of the Exodar as it passed overhead. This could easily explain the Mana Thistle, if it took to the fertile soil on the Isle, but metals don't grow like plants, so this explanation can't really be stretched to the Adamantite.
Do you have an explanation to satisfy the lore-nerds like me? Or are you just happy to have another place to farm?