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Geysers of the World   

Geysers of Yellowstone   



  Lion Geyser
Feature Type: Geyser
Geyser/Spring Type: Cone geyser

Upper Geyser Basin
Geyser Hill

Lion is a fairly large geyser. It was named because it emits a steam puff that sounds like a roar. Some roars are very loud and can be startling. Using one's imagination the overhanging geyserite on its cone also somewhat resembles a shaggy lion's mane. It can reach 50 to 90 feet and last over seven minutes. Lion erupts in a series of from 1 to 30 eruptions, although in 2011 the longest series have had 17 eruptions.

The initial eruption of the series is the tallest and lasts the longest. Unlike the other eruptions of the series, the initial eruption begins with splashing overflowing the cone and ends with a steam phase which can include the roar.

Eruptions other than the initial fall into two categories, majors and minors. Major eruptions last about 4 minutes and minors last about one minute. Both categories can reach about 50 feet in height. Roars can also occur just before or just after an eruption within the series.

Series to series intervals depend greatly upon the duration of the previous series. Recently, they have been as little as 6 hours to over 50 hours. In a series, the interval from the initial eruption to the second in the series, assuming that there is a second, is often between 1 and 1.5 hours. the interval between other eruptions in the series is often about one hour but can rarely be as short as 15 minutes or as long as three hours.

Lion sits on a platform with four other geysers. This is the main part of the Lion Geyser Complex. Lion sits to the northern end of the platform, farthest right on the platform as you look at it from the nearest boardwalk. It has the largest cone of the geysers on the platform. To the left of Lion is Big Cub which has not had a major eruption lately. It usually only splashes, sometimes heavily, prior to a Lion initial. Lioness Geyser sits to the left of Big Cub and also has not had a major eruption in recent times. Lioness spits horizontally within its crater periodically. The last geyser, at the far left of the platform and by far the most active of the Lion Group, is Little Cub Geyser. The frequent splashing eruptions of Little Cub give the geyserite of its cone a pearly looking texture and color.

What to look for:
Prior to an initial eruption, there is little to indicate anything is imminent. Lion will splash periodically and sometimes heavily. Usually Big Cub will also splash and steam periodically. A small bubbler downhill and between Lion and Little Cub noisily erupts to about 6 inches. This activity can go on for many hours with little or no apparent changes before the initial eruption begins. The last splashes from Lion just before an initial are heavier than the others but since judging this intensity is relative it is quite difficult to discern when Lion about to start.

Between eruptions in a series, Lion is quiet until just before the next eruption. Usually, eruptions in the series are preceded by one roar but sometimes can be preceded by a number of roars. The volume of the roar can vary from almost nonexistent to quite loud. Usually as the series progresses, the roars get louder. Sometimes, the series ends with a number of roars spaced a few minutes apart. These roars, sometimes called "terminal roars", do not necessarily mean that the series is over but if the roars continue for a long period and steadily get weaker, the series has probably ended.

Electronic Monitor Files
Lion eruptions for 1998.txtLion eruptions for 1999.txt
Lion eruptions for 2000.txtLion eruptions for 2001.txt
Lion eruptions for 2002.txtLion eruptions for 2003.txt
Lion eruptions for 2004.txtLion eruptions for 2005.txt
Lion eruptions for 2006.txtLion eruptions for 2007.txt
Lion eruptions for 2008.txtLion eruptions for 2009.txt
Lion eruptions for 2010.txtLion eruptions for 2011.txt

Some of the temperature data used to derive the eruption times and durations used in this section were collected by Ralph Taylor under a National Park Service research permit, and the remainder was collected by personnel working for the Geology Department of the Yellowstone Center for Resources (including Ralph Taylor). The loggers are a combination of loggers owned by the NPS and Ralph Taylor. Analysis of the raw temperature data to extract the eruption data was performed by Ralph Taylor. The eruption time files on this website may be used provided that Yellowstone National Park is credited for the temperature data and Ralph Taylor is credited for the eruption times.

Activity in 2011
Activity in 2010
Activity in 2009
Activity in 2008
Activity Recorded by Data Logger - by Ralph Taylor  

Lion Geyser has been monitored electronically since 1998. Data from 1998 to mid-2002 covers only the summer months, generally from late June to early October, but since the mid-2002 we have attempted to monitor Lion all year. There are five large gaps in the record, 30 Dec 2002 to 2 Feb 2003, 21 Feb 2003 to 22 June 2003, 17 Nov to 16 Dec 1003, 7 Apr 2005 to 2 Jul 2005, and 23 to 29 June 2011. These gaps were the result of either logger failure or our inability to download the data resulting in the logger memory filling.

In 2008 a short gap from 1849 on 24 May to 0955 on 27 May resulted from the logger memory filling. The Lion logger failed once again after the November 2008 download, and was replaced on 20 March 2009. The data is continuous for the remainder of 2009 and 2010.
The 2011 data is interrupted by a gap from 23 to 29 June.

Lion Geyser is difficult to monitor. The stream from the eruption is thrown clear of the formation for the most part, and the sensor picks up primarily the big surge of water that initiates the eruption. This surge of hot water also has destroyed several loggers despite our best efforts to protect the devices. In the wintertime ice often diverts water from the sensor and causes some eruptions to leave no indication on the temperature trace.

Lion erupts in series. The initial eruption typically lasts six to eight minutes, and is followed by a series of zero or more in-series eruptions, typically two to four minutes in length. A series typically ends in a series of weak 'roars' that may or may not produce a small amount of splashing. After a series ends, Lion is quiet for several hours.

A complicating factor is the occurrence of minor eruptions within a series. For Lion Geyser, a minor eruption is a short duration (usually less than one minute) eruption that is usually followed in ten to twenty minutes by a full-length eruption. A second complication that makes automatic detection of eruptions from the temperature trace more challenging is the occasional large pre-play splash that produces a temperature signature almost like an initial eruption. These large preplay surges can delay an initial eruption by over an hour.

My analysis program does not distinguish between minor and major eruptions when producing the series length. The eruption files available here give the eruption number in the series as well as the time and interval. For the initial eruption (labeled 'Series Start' in the data files) the interval is the series interval, that is, the time since the start of the initial eruption of the previous series. For subsequent minor and major eruptions within a series (labeled 'Eruption #2' et. seq. in the file) the interval is the time since the previous eruption. In-series intervals of under an hour generally indicate that the preceding eruption was a minor eruption.

In October 2009 Lion Geyser began having very long series, with as many as 20 eruptions in a series. Corresponding series intervals were around two days. The long series continued for the remainder of 2009 and all of 2010, with gradually decreasing series lengths and series intervals. In 2011 the series continue to be longer than pre-2009 series, but the average and maximum length of the series is declining.

Activity in 2007  
The overall statistics for 2007 are shown here.

The series interval graph shows all of the series intervals for 2007. The yellow triangles show the eruption start times for Little Squirt Geyser (up to the end of February when the logger on Little Squirt failed). The Little Squirt eruption times are used as a surrogate for the so-called SMax (South [Geyser Hill] water level MAXimum), which is thought to represent a cyclic change in the hydrothermal energy on Geyser Hill. This hypothesis is described in an article in GOSA Transactions Volume IV titled Cyclic Hot Spring Activity on Geyser Hill, Upper Geyser Basin, Yellowstone National Park—Graphical and Interpretive Descriptions of the Geyser Hill Wave, Diurnal Effects, Seasonal Disturbances, Random (Chaotic?) Events, and Earthquakes by T. Scott Bryan. The green triangles show the first eruption of each recorded Dome Geyser series. Activity in Dome geyser is also known to affect some other features on Geyser Hill. The Dome Geyser logger filled, so no Dome data is available between 15 January 2007 and 1 February 2007.
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The next graph is a histogram of the distribution of series intervals. Note that in this and the other histograms displayed here the labels shown on the X-axis represent the upper boundary of the class, not the midpoint. Geyser times are traditionally truncated. The graph at the right has class widths of 30 minutes. The bar appearing above the label "10:00," for example, contains intervals from 9h31m through 10h00m. The shape of the distribution is generally that of a normal distribution.
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The final series interval graph is the monthly maximum, mean, median, and minimum series intervals.

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The next three graphs show the number of eruptions in a series, the first for the calendar year, the second for the most recent months, and the last as a histogram of the series length. The shape of the series length distribution has remained remarkably similar since I have been monitoring Lion Geyser.

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Activity since 1998  
Lion's activity was been monitored only in the summer months from 1998 to 2002, so the full cycle is not shown on the graphs. The first graph shows all of the intervals recorded since 1998.
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The series intervals have been slightly longer since 2003 than was the case in 1998-2002. This can be seen a bit more clearly in the moving 1-day median graph. Since the last quarter of 2005 the weekly median intervals rose until the last quarter of 2006, then dipped toward the end of the year before rising sharply in 2007 and 2008.

In October of 2009 Lion began having very long series of eruptions, with 20 or more eruptions in some series. The series intervals increased to two to three days since the series were so long. This graph along with the previous graph show the jump in series intervals clearly, and also show a slow decrease in series intervals since the jump. The shape of the decrease appears exponential, suggesting that whatever the nature of the change the system is relaxing to the previous state.

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The final graph shows the monthly minimum, mean, median, and maximum series intervals for all of the data available. This gives another view of the changes over the past decade. Both the average (mean and median) series interval and the maximum series interval are increasing slowly over the years and that the range (shortest to longest interval in a given month) is gradually increasing. The minimum series interval has remained consistent for the whole time covered by the electronic monitoring began.
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The graph to the right shows the number of eruptions (including minor eruptions) per series for the past several years. The October 2009 increase in series length shows very clearly in this view.
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Activity in 2006
Activity in 2005

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Please note - this site is currently under constuction. Please visit for more information.  Last update 01-29-2017

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