Picked up on the recent Yellowstone trip. I already had a third edition (this is the fourth) but a quick perusal in the Norris Basin bookstore disclosed that a lot had changed.


Some definitions:

* Geyser: a natural hot spring that intermittently ejects groundwater water propelled by subterranean steam. The book mentions “cold” geysers that work off carbon dioxide but doesn’t consider them true geysers.

* Fumarole: a vent for subterranean steam.

* Drowned fumarole: a fumarole that has become filled with surface water and therefore spouts or geysers. Drowned fumaroles work with surface water, geysers with groundwater (although geysers can be “drowned” by changes in surface water courses, for example).

* Hot spring: a pool of hot water.

* Boiling spring: as above, but boiling water.

* Spouter: a boiling spring that continuously ejects a column of water. A spouter is continuous, a geyser is intermittent.


Hot springs are pretty common around the world; geysers are rare. The key requirement seems to be recent rhyolite volcanism (rhyolite to provide silica, recent to provide heat). Geysers require a relatively sealed plumbing system; this happens when the hot, pressurized water at depth dissolves silica out of the surrounding rock and redeposits it on the walls of the geyser conduit as “geyserite”. The geyser action takes place when pressurized water at depth heats up enough to finally boil. Once boiling starts, the steam created reduces pressure on the water below it and a positive feedback leads to more rapid boiling until water and steam are ejected out the geyser conduit. If the subterranean plumbing isn’t well sealed, steam apparently leaks out into surround rock and soil and no geysering takes place.


Geysers divide into cone geysers, fountain geysers, and “bubble shower” geysers (Geysers of Yellowstone author T. Scott Bryan notes that sometimes “bubble shower” geysers – basically boiling springs that have intermittent periods of extreme boiling that spray water and live steam – are not considered true geysers. Cone geysers erupt from a relatively narrow orifice in a (usually) cone-shaped geyserite structure; the iconic Old Faithful is a cone geyser. Fountain geysers are actually more common; they erupt from a pool. The action of the eruption is called the “play”.


In the grand geological scheme of things, geysers were originally mostly curiosities. As a result they were treated more as tourist attractions than important sources of geological information. Other than the iconic ones, most of the geysers at Yellowstone remained uninvestigated until the 1970s, and a lot of the investigation was done by curious lay people rather than professional geologists. Examination and record keeping lead to some interesting discoveries: “exchange of function”, where one geyser or group of geysers will activate while another nearby group becomes dormant; “energy surges”, where a group of previously dormant or low activity geysers will become active; and various periodic phenomena. Some of the “energy surges” are triggered by seismic activity; the Hegben Lake earthquake of 1959 triggered many geysers in Yellowstone that were never active before or since. Others are apparently unrelated; there are cases of geysers with more than 100 years between eruptions.


The Yellowstone geysers are grouped into “basins”; on our recent trip it was noted that at least in the Upper Geyser basin (home to Old Faithful) this is a misnomer and most of the geysers are actually on a raised area with water draining away rather than into the “basin”. We speculated this was due to subsurface sealing by geyserite; the geysers run off deep groundwater, not surface water. The Yellowstone geysers basins are: West Thumb, Upper, Midway, Lower, Gibbon, and Norris (major tourist attractions, accessible by car) and Third (sometimes called “Lone Star”), Shosone, and Heart Lake (only accessible by hiking trails). There are a few isolated geysers here and there elsewhere in the park; most are only accessible by backcountry hiking (Bryant notes that “Fairyland Basin”, which requires a full day of backcountry hiking followed by a technical descent into a deep canyon, has only been visited ten times in the history of the park; as of the 2007 publication date of this book the most recent visit was 1992, and it isn’t even clear if there are actually geysers there). Yellowstone has more geysers than the rest of the world combined; any of the geyser basins (with the exception of West Thumb) would be in the top five of world geyser sites (and West Thumb would have been there in the past when more of its geysers were active). I was surprised to find that there is no organized monitoring program for the Yellowstone geysers; an amateur group, The Geyser Observation and Study Association, has transcribed written logs and keeps some records of eruptions, but the online data seems to be incomplete and out of date.


More detailed observations would allow investigation of geyser periodicity. Old Faithful, of course, is the example here and its eruptions can be predicted fairly well; Bryant notes it isn’t simply of matter of a simple time series but the duration of each eruption affects the time to the next one. Large scale periodic phenomena have been noted; Geyser Hill in the Upper Geyser Basin undergoes the Geyser Hill “wave”, which propagates from southeast to northwest across Geyser Hill on a variable cycle of 4 to 12 days, causing an increase in geyser activity as the wave reaches each affected geyser. There is also a diurnal cycle on Geyser Hill, with eruption intervals shorter during the day than at night. A similar phenomenon is the Norris Basin “disturbance”, which has been observed as far back as 1878. In August and September of almost every year, geyser activity in Norris Basin increases; old geysers become more active and new ones appear. It’s theorized this has to do with the availability of cool surface water penetrating to depth; when surface water flow decreases in the late summer and early fall the hotter deep water regime takes over. Interestingly, while the “disturbance” increase the activity of most of the Norris Basin geysers it paradoxically decreases the activity of Steamboat Geyser, currently the world’s largest (the much larger Waimangu Geyser in New Zealand hasn’t erupted since 1904 and the marginally larger Excelsior Geyser in the Midway Basin at Yellowstone hasn’t erupted since 1985; Steamboat last erupted on July 31 2013). The Norris Basin as a whole is the most variable of any of the Yellowstone basins; the earlier edition of this book describes many geysers at Norris that haven’t been active for years, and there are new ones that don’t appear in the current edition. (The Norris Basin is also considered the most likely location for another caldera eruption at Yellowstone).


There are other geyser areas around the world – even a few more in the US, notably Beowawe, Nevada (now probably extinct due to geothermal development). New Zealand and Iceland are the most accessible, although both are in danger of compromise by geothermal development. Outside of Yellowstone the largest geyser fields are Dolina Geizerov in Kamchatka (second largest in the world after Yellowstone but only reachable by a 120-mile helicopter flight from Petropavlovsk and only open for day use) and El Tatio in Chile (third largest but only reachable by a 50-mile car trip on a 4WD only road; you can primitive camp-there but it’s at 13800 feet).


Well worth it as a field guidebook; just the right size to fit in a handy pocket. One of these days I’ll have to try and get back to Yellowstone and just spend a whole week in the Upper Basin geyser gazing. ( )

Hands down, this is THE holy book of anyone with even the slightest interest in geyser phenomena. Complete, up to date, definitive and thoroughly indespensible.

If you are a passionate about geyser observation, if you are a fan of geysers, in fact, even if you have just a passing fancy for geysers, there is no better book to include in your collection. This is the fourth edition, and Mr. Bryan does himself proud (one more time). I ordered the book as soon as I knew it was available. (Side note, I purchased it through the Geyser Observation and Study Association bookstore. If you are thinking of purchasing this book, go through the GOSA web site and help promote geyser studies. No, I don’t get any kickbacks for this recommendation.) My copy of the third edition was getting a bit threadbare and out of date. I received this copy and immediately read it cover to cover. And, no, this isn’t the kind of book you should read that way – but is has such fantastic detail, I couldn’t help myself. This book primarily consists of a geyser by geyser description of every true geyser (or feature that has acted like a geyser in the past) that exists in Yellowstone. (And sometimes that may mean a feature that went off for a few months to a height of two feet – but that means the book is sure complete.) It has additional details on the geyser areas, hints on how to access some of the out of the way places, and even information on geyser fields outside of Yellowstone. It includes the latest information on patterns for geysers, eruption intervals and eruption durations. And it even describes some of the idiosyncrasies that might help you predict the geysers while you’re out in the field. (There have been at least two instances where the information in this book helped me realize an eruption might be imminent, resulting in my sticking around to see Great Fountain and Oblong Geysers go off.) If you are not a geyser geek, a lot of this won’t make sense. But, again, even if you have a passing fancy, or if you are looking for a field book to take on your next trip to Yellowstone – this is the book. ( )

THE ultimate geyser reference! ( )