Twin Buttes in Lower Geyser Basin, with Excelsior Geyser of Midway Geyser Basin in the foreground

Photograph of Twin Buttes in Lower Geyser Basin looking to the northwest, with Excelsior Geyser of Midway Geyser Basin in the foreground. Twin Buttes is a thermal kame that formed when glaciers covered the area, and hydrothermal activity below the ice led to melting and the deposition and cementation of glacial sediments. Excelsior Geyser, the large steaming spring in the foreground, was formed by a series of small hydrothermal explosions in the late 1800s. Photograph by Lauren Harrison, U.S. Geological Survey, July 27, 2021, under permit YELL–2021–SCI–8158.