One visit is never enough to get the real feeling of a place. Hal Crimmel, a former river guide and a professor or writing and literature at Weber State University, recognized that in Dinosaur: Four Seasons on the Green and Yampa Rivers (The University of Arizona Press, $14.95).

Crimmel and photographer Steve Gaffney made multiple trips across the seasons to capture what the Green and Yampa rivers are all about. Information ranging from the ancient history of the area to the first white explorers to current threats is included in the book. It is a fine example of the quality of work that can be done when time is dedicated to a project. The book is available through The University of Arizona Press, $14.95, as part of the Desert Places series.

- Brett Prettyman