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Geysers of the World   

Geysers of Yellowstone   



  A-1 Geyser
Feature Type: Geyser
Geyser/Spring Type: Fountain geyser

Lower Geyser Basin
Great Fountain and White Creek Group

Historically A-1's activity interchanged with A-2. When one was active the other was dormant to nearly dormant. Botryoidal Spring has taken over the activity of both A-1 and A-2, which are currently considered to be dormant. When active A-1 reaches 6 feet for 5-10 minutes and intervals are about 30-40 minutes apart.

What to look for:
This is a generic desciption that applies to pre-eruptive play in most geysers. One or more of the following changes may occur: water level rises and overflows; water level pulses up and down; water bubbles, domes up or splashes; boiling steam bubbles appear. The intensity of these actions may increase over time. However, there may be no prior warning at all. All observations must be made from a legal trail or boardwalk in order to avoid injury and environmental damage. Consider what the impact of your actions would be if repeated by millions of others. Please report any activity to the nearest Visitor Center.


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

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