Animals of all sizes sometimes break through the thin crust in hydrothermal areas or simply step in the wrong place.
Over the years, at least two bison have fallen into Scalloped Spring in the
Upper Geyser Basin. Both times the unexpected intrusions caused Scalloped Spring
to erupt as a geyser. The eruptions lasted for a couple of days, throwing water as
high as 10 feet (3 m) into the air.
photo courtesy of Charles Johnson
The eruptions, coupled with human vandalism in the 1950s, have altered
Scalloped Spring’s appearance. Once it looked very similar to its neighbor,
South Scalloped Spring; water overflowed from its basin, and it was rimmed with
delicate, crinkly edges. Now its water level is well below the surface, and the
lovely scallops have been destroyed.