This book applies the principles described in Bailey's Ecosystem Geography to describe and characterize the major ecological zones of the Earth, both terrestrial and aquatic. Bailey's system for classifying these ecoregions has been adopted by major organizations such as the US Forest Service and The Nature Conservancy, and this book will be a major contribution to a long tradition of classifying and studying the world's ecological regions. "Bob Bailey [is] the man behind the ecosystem mapping of the world." -- Lingua Franca Robert Bailey's work has had a major influence on the Forest Service's decision to adopt an ecosystem-based approach to managing public land. This book extends his work globally, and includes two color maps--showing the major ecoregions of the continents and of the oceans.