West Thumb Geyser Basin (WTGB), along the southwest shore of West Thumb Basin in western Yellowstone Lake, is one of Yellowstone’s most scenic and interesting thermal basins and contains an impressive variety of thermal features. The combination of beautiful blue, deep pools, pastel-colored mud pots, stark white sinter terraces, and expansive views of West Thumb Basin and the Absaroka Range to the east make WTGB a beautiful place to explore from the extensive boardwalk system. West Thumb Geyser Basin has active but infrequent geyser eruptions.
More common are the blue, very hot (at or near the boiling point of water), and deep thermal pools and the white, extensive siliceous sinter terrace deposits that form due to overflow, evaporation, and cooling of silica-rich thermal fluids. The hot spring pools are steep sided inverted cones that form by dissolution of the rhyolite or sinter substrate, with enhancement by occasional hydrothermal explosions and wall collapses. At WTGB, an array of red, orange, pink, and green thermophilic bacteria are common along drainage channels, on the sinter terraces, and around the peripheries of hot springs and mud pots.
Intermittent geysers at WTGB include Occasional Geyser, Twin Geysers and Lakeshore Geyser, among others. Twin Geysers and Abyss Pool produce occasional violent eruptions. Twin Geysers erupted in 1934, sending hot mud, sticks and boiling water about 65 meters (120 feet) high.
Abyss Pool erupts occasionally to heights of 30 meters.
