What rock type are you thinking of?One thing that annoys me about Geostrata (and may mean I disable the mod next world) is that stone with a higher mining level can spawn anywhere. It means that even very early on (within the first 10 layers down) you are having to dig around rock until you get a better pick. I would have thought it appropriate (given minecraft mechanics) to have harder stone only spawning at lower levels. Reika, is this an intended effect?