Looks to me as though some reasonable fellow just wanted to sharpen some pointy sticks and maybe sharpen some flint,...as if he simply used a hard rock to make some arrowheads,...as one area became worn he made a new notch to keep his edge honed,...then again I'm just being simple about it,....perhaps its the key to a subterranean preCambrian nuclear reactor connected to the Doomsday machine like Ambassador DeSadesky alluded...