Towers of Stone by J.L. Crawford summarizes the essence of Zion National Park, its landscape, plants, animals, and human history.
Zion National Park: Sanctuary in the Desert by Nicky Leach gives you a photographic overview and a narrative journey through the park.
An Introduction to the Geology of Zion by Al Warneke contains information about the geology of Zion in a small booklet.
The Zion Tunnel, From Slickrock to Switchback by Donald T. Garate tells the fascinating story of the construction of the mile-long Zion Tunnel in the 1920s.
Wildflowers of Zion National Park by Dr. Stanley L. Welsh is always helpful during wildflower season.
Contact the Zion Natural History Association (800/635-3959. www.zionpark.org) for all of these books and more.