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Geysers of the World   

Geysers of Yellowstone   



  Little Cub Geyser
Feature Type: Geyser
Geyser/Spring Type: Cone geyser

Upper Geyser Basin
Geyser Hill

Little Cub Geyser is a member of the Lion Complex and sits at the far left of Lion's platform. Its connection to Lion Geyser is still being investigated.

The bursting play of Little Cub's relatively frequent eruptions, normal interval of about 30-90 minutes and duration of about 10 minutes, has built up a beautifully sintered formation covered in small pearly bumps. Little Cub erupts to a height of about 10 feet. Because it sits high on Lion's platform, it is not possible to see into Little Cub from the boardwalk. Thus, the eruption can appear to come without warning.

What to look for:
Little Cub will spit out a few drops prior to erupting. This activity increases in intensity and height gradually leading up to an eruption.

From 2014 to 2016, there have been occasional reports of Little Cub getting "stuck" in pre-play, to use the reports' term. Sloshing and splashing can continue for quite some time, but eventually ends without an eruption. It is not yet certain whether there is any rhyme or reason to this "stuck" behavior, but the geyser eventually does become "unstuck" and resumes its 10-foot eruptions. Reports from the 2017 season may prove illuminating.

Electronic Monitor Files
Little Cub eruptions for 1998.txtLittle Cub eruptions for 1999.txt
Little Cub eruptions for 2000.txtLittle Cub eruptions for 2001.txt
Little Cub eruptions for 2002.txtLittle Cub eruptions for 2003.txt
Little Cub eruptions for 2004.txtLittle Cub eruptions for 2005.txt
Little Cub eruptions for 2006.txtLittle Cub eruptions for 2007.txt
Little Cub eruptions for 2008.txtLittle Cub eruptions for 2009.txt
Little Cub eruptions for 2010.txtLittle Cub 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 Recorded by Data Logger - by Ralph Taylor  

Little Cub Geyser has been monitored electronically since 1998. From then to 2003 the monitoring was during the summer only; starting in June of 2003 we have attempted year-round logging.

Activity in 2011  
The overall statistics for 2011 are shown at Little Cub Statistics for 2011.

The interval graph shows all of the intervals for 2011. The orange triangles show the eruption start times for Little Squirt Geyser. 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.

Eruptions of Giantess Geyser also affect many features on Geyser Hill. Giantess Geyser eruptions are noted by a yellow triangle.

Click for a larger image

The next graph shows the intervals for the past few months at an expanded time scale. When Little Cub is having its regular eruptions (that is, with none of the non-erupting periods of overflow) the intervals in 2010 and early 2011 have been between 35 minutes and about 55 minutes. As in the previous graph the orange triangles show the eruption start times for Little Squirt Geyser and green triangles indicate Dome Geyser series starts.
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The graph at the right shows Little Cub's intervals for the past month.
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The next graph is a histogram of the distribution of 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 2 minutes. The bar appearing above the label "1:12," for example, contains intervals from 1h11m through 1h12m.
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The final graph is a histogram of the measured durations.
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Activity since 1998  
Little Cub'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. Since mid-2003 the record is nearly complete. For many years Little Cub was regular in its eruptions on any given day. Intervals would vary only a few minutes from one eruption to the next. In some seasons the intervals would suddenly increase or decrease by about 10 minutes, but other than that Little Cub kept a steady pace.

In late 2003 (the first year for which we had winter data) I noticed that there were long gaps in Little Cub's eruptions, at first only a bit over two hours, then by early 2004 some periods of inactivity were as long as 12 hours. The winter of 2004-5 saw the longest pauses, some of which were more than three days in length. By late winter the intervals were shortening, or more accurately, the incidence of very long intervals (dormancies?) decreased. By the time I arrived at Old Faithful, Little Cub was erupting regularly again and it was some time before I was able to see the activity that produced the long gaps. During one of my visits to Geyser Hill to download loggers I noticed that Little Cub was bubbling and overflowing, but the activity did not reach more than a few centimeters over the rim. Apparently the long pauses are the result of this sort of low intensity boiling and overflow. The dormancies (?) occur mostly overnight or in the early morning hours, so perhaps there is a cooling effect from either air temperature or cooling of water somewhere on the Lion platform.

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The moving median (I used one day, or 20 eruptions) graph shows the effect of the long intervals (or short dormancies) on Little Cub. During the summer of 2005 Little Cub had few of the gaps in eruptions as the two graphs here show. Intervals during the summer of 2005 were the lowest since I began monitoring Little Cub. By the middle of 2006 the common daily intervals were often in the 40-50 minute range once again, and for the four winters for which data is available a noticeable annual cycle of short summer intervals and longer winter intervals is evident. Reference to the interval graph shows that the shortest intervals remained about the same all year and that the rise in the daily median interval in the winter months is probably due to the periods of dormancy.

Unfortunately the data from 1998 to 2002 is too short to reveal the presence or absence of this annual fluctuation of intervals

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Activity in 2010
Activity in 2009
Activity in 2008
Activity in 2007
Activity in 2006
Activity in 2005

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

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