What do ancient reptile fossils have to do with radioactive atoms deep inside the Earth's mantle? What causes earthquakes and volcanic eruptions? Why are there strange creatures living deep beneath the ocean surface, where hot water and chemicals spew out of cracks in the ocean floor? The answer to all of these is the same: plate tectonics. Over the last century, scientists have discovered how heat generated deep inside the Earth drives movements of the mantle and crust - and how in our Solar System, this process is almost unique to our home planet. All of this is real, cutting-edge science, written at a level that kids can read and understand. At the end of the book, you will find a self-quiz to test your new knowledge and fun hands-on activities that build on the science.Judith Hubbard is a geology professor with a Ph.D. from Harvard University and a B.S. from Caltech - and also two young children. She started the In Depth Science series with the goal of making college-level science accessible to kids as young as eight years old.