This new edition of The Geysers of Yellowstone is the most up-to-date and comprehensive reference to the geysers of Yellowstone National Park, describing in detail each of the more than five hundred geysers in the park. The entire text has been revised and geyser descriptions have been updated based on activity observed through early 2018. Information about a number of significant new geyser developments has been added, as well as recent knowledge about some of the world’s geyser fields outside Yellowstone.   Both a reference work and a fine introduction to the nature of geyser activity, this popular field guide includes a glossary of key terms, a comprehensive appendix that discusses other geyser areas of the world, detailed maps of each geyser basin, and tables for easy reference. The Geysers of Yellowstone will continue to serve geyser gazers as well as newcomers to geothermal phenomena for years to come.   Praise for previous editions: “A tribute to and a tool for the geyser gazers. . . . Any visitor to Yellowstone for whom geysers carry an appeal at all needs the guide.” —Scientific American   “ The Geysers of Yellowstone tells the story of more than 700 springs, geysers, steam vents, and fumaroles in the park. And in Bryan’s naturalist–former park ranger hands, the stories are fascinating, hitting on the history, geography, and science of Yellowstone’s geothermal phenomena. He’s done pretty much all the work for us. There are maps, directions, descriptions, cautionary notes, photographs—you name it. All that’s left is to grab the guidebook, stuff it in a backpack, and head for hot water.” — The Missoulian   “Bryan himself writes with vibrant, engaging prose, which is an asset in a guidebook. . . . even the casual reader will be amazed.” —Montana the Magazine of Western History T. Scott Bryan was a seasonal employee at Yellowstone National Park from 1970 through 1986. In addition to his studies in Yellowstone, he has been to geyser fields throughout the contiguous United States, Mexico, Japan, Fiji, New Zealand, and the Valley of Geysers on the Kamchatka Peninsula of Russia, leading the first-ever US study group there in 1991.   The Geysers of Yellowstone By T. Scott Bryan University Press of Colorado Copyright © 2018 T. Scott Bryan All rights reserved. ISBN: 978-1-60732-839-1 Contents List of Illustrations, Foreword by Lee H. Whittlesey, Park Historian, Yellowstone, National Park, Preface, A Special Warning — Travel in Off-Trail and Backcountry Thermal, Areas, 1 About Geysers, 2 Some Background on the Yellowstone Geysers, 3 Geyser Basins of Yellowstone National Park, 4 Upper Geyser Basin, 5 Midway Geyser Basin, 6 Lower Geyser Basin, 7 Norris Geyser Basin, 8 West Thumb Geyser Basin, 9 Gibbon Geyser Basin, 10 Lone Star (Third) Geyser Basin, 11 Shoshone Geyser Basin, 12 Heart Lake Geyser Basin, 13 Other Yellowstone Geysers, Appendix: Geyser Fields of the World, Glossary, Suggested Reading, Index to Yellowstone Geyser and Hot Spring Names, Group Abbreviations for Unnamed Springs, About the Author, CHAPTER 1 About Geysers What Is a Geyser? The standard definition of geyser in general worldwide use reads like this: A geyser is a hot spring characterized by intermittent discharge of water ejected turbulently and accomplished by a vapor phase. It sounds simple enough, but it really is not. The definition includes several "gray areas" that can be interpreted in different ways — how hot is hot; how high must the turbulence be; are there limits as to how long or short the intermittency needs to be? Such questions will probably never be answered to everyone's satisfaction, but there are two similar varieties of hot springs that definitely do not qualify as geyser. Intermittent springs undergo periodic overflows but never actually erupt; and perpetual spouters (called pulsating springs in some parts of the world) may erupt, but their action never stops. In all three of these cases, however, the cause of the eruption is the same — namely, the formation of pressured steam (a "vapor phase") at some depth below the ground. What Makes a Geyser Work? Three things are necessary for a geyser to exist: an abundant supply of water, a potent heat source, and a special underground plumbing system. The water and heat factors are fairly common. Hot springs are found in virtually all of the world's volcanic regions. The plumbing system is the critical aspect. Its shape determines whether a spring will be quiet or will erupt. It must be constructed of minerals strong enough to withstand tremendous pressure, and it must include a permeable volume so as to hold the huge amounts of water ejected during an eruption. Nobody really knows what a plumbing system looks like — it is, after all, belowground and filled with hot water and steam. Considerable research drilling has been done in some of the world's geyser areas, and apparently no dril