Why do thunderstorms form over the mountains? How do water bugs float on the surface of pools? What the heck is the Laramide orogeny? This classic guide, just reissued in less-expensive form, holds the answers to thousands of hikers' questions. The ecosystem-specific chapters, each with a drawing and photographs, are easy to navigate and guaranteed to give a richer understanding of the wild Rockies.
Price: $24.95
Where to get it: Most bookstores and fulcrumbooks.com
Bonus: Does the job of at least six guidebooks, making it lighter on your pack.
Bummer: The Laramide orogeny isn't nearly as scandalous as it sounds. It's the geologic uplift that created the Rockies.

This book is a gem. Although it is called a field guide, this 656 page book can serve as a reference book or can be read from cover to cover. It would be worthwhile to take this readable book along on a road trip or camping trip for night- time reading.