In the book of Revelation, the author has a vision of the future where the heavens are rolled up like a scroll, and every mountain is “removed from its place“. Then the next thing he sees is everyone hiding in caves and among the rocks of the mountains. How can they do that if the mountains aren’t there anymore?
Maybe “removing” the mountains from their place just means relocating them to different places where people can still get to them. That’s a perfectly logical interpretation of what it says, but not a particularly natural one. (It’s not how I would expect someone reading the first verse to interpret it, unless they were looking for a way to reconcile it with the second one.) And just moving the mountains seems like a pretty pointless thing to do.