Even land that is now very diverse once started out as what?

As of right now, the land is pretty spread out. But millions of years ago, like, we're talking dino time, all the land was just one chunk. This chunk was called Pangaea, or Pangea. But before everything split apart into multiple continents, there was just one; a supercontinent. Hope that helps!

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.