The book is Forest Giants of the Pacific Coast.
An absolute gem for any dendrophile or woodsman. It is out of print but still available.
Van Pelt is well known for his work with big and old trees.
Years ago he teamed up with the WA Department of Natural Resources to create a guide for identifying mature stand structure and old growth trees. It features some photos and illustrations from Forest Giants of the Pacific Coast.
Though different in scope, the guide is also a gem with the added benefit of being free.
Anyone interested in learning about and understanding PNW forests would benefit greatly from these guides.