Pink Cone Geyser is a pretty cone-type geyser. In recent years intervals have varied from 18 to 25 hours, with an average interval of 22 1/2 hours in 2009. Durations are about 1 1/2 to 2 hours and the maximum height is about 30 feet.
It is somewhat surprising the geyser has survived through the history of the park. Prior to 1937 no eruptions were seen. This dormancy may explain the disregard it was shown by early park administrators. The road past Pink Cone actually cuts through the platform that the cone sits atop. It was fortunate that this didn't result in irreparable damage to Pink Cone's plumbing system. It did cut into some minor near surface channels which can sometimes be used to help anticipate the time of the next eruption but nothing worse appears to have been damaged. Cutting the road also exposed a cross section of a geyser platform so that you can easily see the layers of sinter.
When active between its reactivation in 1937 and the 1959 Hebgen Lake earthquake, Pink Cone's intervals were about 50 hours. During the days after the earthquake it erupted almost continuously. In the years following the earthquake, the intervals gradually increased. From 2005 through 2009 the average interval increased from 20 hours to 22 1/2 hours.
Pink Cone is also known to have small mid-cycle eruptions which look very similar to a normal eruption. These small eruptions consist of discontinuous jetting, last up to 15 minutes and may only reach a few feet, although some eruptions have reached more than 20 feet. Because they look similar to the end of a full eruption, care must be taken not to confuse these with a full eruption when reporting sightings of this geyser.
|Pink Cone is the only geyser of the group that is easily seen from the road. Even so, for most of its interval, there isn't much to see. As the time for the next eruption approaches, water can be heard sloshing in the vent. Eventually the water level and splashing are strong enough that occasional splashing and jetting can be seen above the cone. This jetting may completely cover the platform with water during long intervals. This jetting gets stronger until one jet finally triggers the eruption. Alternatively, some eruptions start with the first jetting activity.
At times, it is possible to use three very small vents in the road cut to anticipate the time of the next eruption. These small vents were created when the road was constructed and a minor portion of Pink Cone's plumbing system was inadvertently tapped. The three vents, often called the "road bubblers", appear to indicate the water level in the system. In recent years the road bubblers have started about 18 or 19 hours after the preceding eruption. When Pink Cone has a short interval, the road bubblers may not be active prior to the eruption. When Pink Cone has a long interval, the road bubblers may be active for 3 or more hours before the eruption. The bubblers are hard to find unless you know where too look. Thus, it is best to get someone to show you.