This book is wonderful because it covers so many subjects. It's got sky charts, geological information, plants, fish, mammals, birds... The diversity of subjects is also its greatest weakness. It simply can't afford to go into great depth about any of them. I tried actually taking this book into the field and was sorely disappointed -- nothing that I needed to look up could be found in it. It's a wonderful book, but a poor field guide for anyone serious about the outdoors. ( )