Rocks are literally underfoot and can tell marvelous stories. The authors of this book have been spellbound by rocks for most of our lives. We have been astounded at the story of how the dinosaurs were killed by an asteroid crashing into Earth from outer space, and we smile at the idea that the rocks now at the top of Mount Everest were formed beneath the surface of an ocean. We have both spent time enjoying the splendor of Grand Canyon and pondering the incredible stories recorded in the rocks that are exposed in the cliffs and along the bottom (Figure 1.1).