Yes, but we are talking about a different state, and a different type of flat. That quarry is clearly a hard stone quarry (e.g. granite) due to its appearance in the film. Sorry, I'm no geologist, but you are extremely unlikely to get anything other than sedimentary rock at the very best on the generally flat and friable terrains that Iowa is best known for. Certainly not in the manner the film portrays. Where's Oerdin when you need him?