Uncertain Geyser.

Once again we're back to the temperamental and spellbinding Sawmill Group in the Upper Geyser Basin. The last time we were here we discussed Penta Geyser. Now we are going to discuss Uncertain Geyser, a favorite among several Geyser Gazers, and a geyser that proves somewhat elusive to catch.

Sawmill Geyser is the dominant geyser in the Sawmill Group, photo by: Micah K.

Everything in the Sawmill Group is affected by, of course; Sawmill Geyser. Uncertain is no exception. After every eruption of Sawmill the water levels in the group will drain several feet and then refill. This happens several times over until Sawmill has a much longer duration eruption, usually this is several hours long instead of the typical 90 minutes. After this eruption finally ends, the Sawmill Group undergoes a "Deep Drain" where the water levels in all the features plummet for several hours, in most of the springs it is even impossible to see water. After a few hours goes by the water levels begin to recover, and this is where the fun begins.

Twilight Spring in the Sawmill Group recovers from a drain following an eruption of Sawmill. Photo by:Micah K.

 Several features in the Sawmill Group only erupt, or usually erupt when the water level is coming up from a deep drain. Uncertain Geyser is one of those. Uncertain's crater is nothing more than a small nearly circular hole tucked against the thick geyserite shoulder of Sawmill Geyser. It is a race between Uncertain and the rest of the group. If nearby Twilight Spring reaches overflow before Uncertain erupts, the game is over, if Tardy Geyser nearby erupts first, usually that spells doom for the chances of Uncertain. If Sawmill Geyser erupts first, it usually isn't a good sign, but sometimes Uncertain will erupt in concert with Sawmill for a fantastic show. See how complicated the relationships are? Fantastic right? It's patterns and puzzles like these that make geyser gazing so much fun!

Despite it's unfortunate knack for keeping Uncertain from erupting. Tardy Geyser just down the boardwalk still puts on quite the show of its own. Photo by Micah K. 

As the water level comes up in the Sawmill Group, usually Uncertain will splash within it's vent or pulse up and down. If an eruption will occur, the water level will rise to the top of the rim and the splashing will grow vigorous, finally the splashing will turn into jetting, and neat little fountain of water will spray 10-15 feet into the sky for about five minutes. The eruption ends with a small steam phase.

Uncertain Geyser erupts! Photo by Micah K

For me the reason that I enjoy Uncertain so much is simply the buildup. The tension that occurs once you see all the criteria are in place and that the race is on between Uncertain and the other features is very fun. I'm sure I got many weird looks from visitors as I scampered from feature to feature jotting things quickly in my logbook before running to the next feature. But you know what, I loved every second of it.