THE DESIGN OF THIS BOOK aims to make your reading and studying as efficient and enjoyable as possible. In normal textbooks, two major challenges are trying to decide what is most important and how the text relates to the figures. This book simplifies that process because the text and figures are already tightly integrated. The design of the text consists of a series of 200 two-page spreads. Each spread is designed to concisely convey the important aspects of a geological concept or system. The two-page spread design was greatly influenced by educational and cognitive research on how people learn. Also, this text has been designed to encourage inquiry and provide readers with tools to think critically about geologic problems. Questions in the title, opening paragraph and topic headings are intended to get readers to think about the topic and become interested and motivated to explore the two-page spread for answers. The authors also use a learning-cycle approach in presenting topics. This approach includes three phases exploration, introduction of terms and concepts, and application.