Nugget 8: The Moods of West Thumb Geyser Basin

Yellowstone Park's most beautifully situated hydrothermal area is West Thumb Geyser Basin. Reflecting the different times of day and seasons of Yellowstone Lake and the Absaroka Range of mountains beyond, West Thumb's hot pools rest in a tranquil and unique spot.

The few geysers this geyser basin actually has are usually not predictable. Lakeshore Geyser did have a period of heightened activity in the winter of 1999–2000. It's so close to the shore that for much of the year it stays under water. Then there is Twin Geysers, which sometimes erupted to 100 feet first from one crater, then from the other—but that occurred mostly in the 1970s. Lone Pine Geyser erupts once or twice a day out to the north of the main geyser basin. Its namesake tree fell into the lake a few years ago. A tall and frequently erupting geyser appeared in this geyser basin a few years ago. Hillside Geyser, which erupted to around 70 feet (20 m) about once a day, has been dormant since 2006.

Historically famous is Fishing Cone (right), now sometimes submerged in the lake. In early park days, the cone was a spot where fishermen would stand to catch a cutthroat trout and cook it immediately in the hot spring—a great way to have fresh trout, but an activity that's no longer allowed.

Hot pools in many shades of blue are sprinkled throughout West Thumb Geyser Basin. Seismograph and Bluebell pools are side by side (left) but may show different colors. They differ from each other in temperature.

Black Pool (left) was clearly not black in the last few years. In 1991 it became very much hotter than before and erupted, killing the bacterial mats, whose oranges and browns had combined with the usual blue of the water to make the pool almost black. Now Black Pool is often a lovely blue or green and is gradually cooling.

Two lines of pools with varying shapes, sizes, and temperatures make up the center of the basin. The upper group are the Painted Pools, seen (right) with a small mud cone in the foreground that belongs to the Thumb Paint Pots.

CREDITS: The overall view with mud cones is by Janet Chapple; all other photos on this page are by Bruno Giletti.

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You can find out about hydrothermal features in other basins in Hot Springs and Pools of Many Colors.

Revised January 7, 2008. Copyright 2001–2008. All Rights Reserved.