My family's house sat on a hill. My father fought a never-ending battle with geological forces to prevent his driveway from washing down the hill into the street with every heavy rain. One of his more successful maneuvers was graveling the thing with a heavy, gray aggregate, like you'd find on a railroad bed. We boys would stand in the driveway and ping those rocks with baseball bats for hours, much to the annoyance of my father and the neighbors down the hill, I'm sure. I'm surprised we got away with it at all. I suppose boys would be boys back then.