It's often hidden underground, but soil is a complex mixture of rock, organic matter, gases, and water. Soil forms very slowly and is made up of several layers--which readers can learn all about in this book! In the main text, they uncover the many different types of soils, each of which play a crucial role in the lives of many living things on Earth. Eye-catching graphics, age-appropriate text, and helpful diagrams combine to make for an excellent reading experience. Readers put their knowledge to the test at the end with a quiz.