From Pangea to precipitation, hydrology to halite, this eBook provides essential test prep in all the key Earth science topics. Designed both for students new to the Earth sciences and those in need of a refresher, you'll find a series of 20-minute 20-step lessons that are precise, guided, and easy to fit into any schedule. There's also a full glossary, practice tests with answers and explanations, and bonus sections including tips for preparing for standardized tests and guides to further resources.