Television can be educational. Yesterday, I was watching a show on the History Channel called "Modern Marvels," and this particular episode was about rock quarries and how our civilization is dependent on various types of rock and rock products for materials used in buildings, roads, concrete, etc. One little factoid for you: The white powder on the inside of your chewing gum wrapper that keeps the gum from sticking to the wrapper is made of sweetened powdered marble. Believe it. Another factoid: Each mile of two-lane road takes about 40,000 tons of rock to make. There are about 3.9 million miles of road in the United States. That's a lot of rock.