Scott Bryan explains the geological setting that produces the pressure, heat, and abundant water necessary for a geyser to form and introduces us to the varibles that shape each geyser's distinct personality. Some geysers spout just inches above a pool of water and others blast hundreds of feet in the air from conical vents. Some remain quiet for decades only to explode unexpectedly several times in a single month while others erupt regularly in scheduled intervals, year in and year out. While Bryan focuses on Yellowstone National Park, he also draws examples from geyser fields in Iceland, Chile, Russia, New Zealand, Africa, and elsewhere. An appendix with a detailed map describes the status of more than sixty geyser fields around the world. The book includes old photos of many now-extinct geysers and explains the natural and man-made causes of their demise. Includes 76 color photographs, 3 maps, appendix, glossary, references, and index.