Side note, but...
Ground > Steel.... well, look at
this, and you might get some ideas :)
This was actually due to wind, not an earthquake.
However, a good place to look would be
California. Bridge collapse because of the wrong kind of stable construction? Fun times.
Of course, Steel is inmune to Poison, because of not being living tissue to begin with.
By this logic, wouldn't it make sense to have Rock immune to Poison as well, given the fact that rock's not living tissue as well? (Just saying there may be more to this immunity here than just what's living tissue. Otherwise, we'd also have to explain why Rock doesn't get the same immunity.)
So, that's always confused me. Why
isn't Rock immune to Poison? Or, for that matter, Ghost, considering the fact that ghosts (as in, actual ones), by definition, aren't living material either? (Those who say they
are immune are probably looking at the Gastly line.)
As for the recent comment about Fighting being effective against Steel or Rock, it's mostly like this:
Fighting vs. Rock: One of the clichés to martial arts is to have a kung fu (or whatever) master break cement blocks or rocks with a single karate chop. It's a sign of strength or at least knowing how to use one's body to fight. Hence, Fighting > Rock.
(Note: By this logic, one would have to wonder why it's not true that Fighting > Grass, given that actual martial artists start with breaking wooden boards.)
Fighting vs. Steel: A cliché of superhuman strength. Basically, if you're a superhero who possesses an incredible amount of muscle power, you're able to bend rods of steel with no problem. (See Superman.)