Huh. My boss gave me this book to read called Assembling California by John McPhee. This is hard geologic science stuff. Of course I love it. This is a description of the Sierra Madre from a geologists point of view: "This is the Sierra Batholith. (One REALLY large rock). The one in California has a surface of about twenty-five thousand square miles.It lies inside the Sierra like a big zeppelin." They think it goes six miles down. "If so the batholith weighs a quadrillion tons, and its volume is at least a hundred and fifty thousand cubic miles." That is a pretty big peice of granite.