Grimstone shouldnt be nearly HALF of the underground

The grimstone caves look good don't get me wrong... but the fact that EVERY cave below Y0 is grimstone just doesnt feel right. I think if there were to be maybe 3 levels of deepness in the world, each with their own block (gradually getting darker as you descend through the world) that would make these grimstone caves be a scary and interesting thing at the bottom of the world. also the slightly lighter caves feel a lot more spacious and fun to explore.