Mammoth Hot Springs is famous for its travertine terraces. Travertine is deposited in the Mammoth Hot Springs area (in contrast to siliceous sinter in the geyser basins to the south). A thick sequence of sedimentary rocks (mostly limestone and dolostone formations of Paleozoic age) underlie the landscape in the area. The travertine is forming at the expense of carbonate rocks dissolving underground in the surrounding mountainsides.
This picture shows possibly one of the series of travertine terraces in the lower terraces area of the Mammoth Hot Springs. Historically, the white travertine deposits are collectively part of the larger "Capitol Hill" series of spring terraces in the vicinity of Mammoth Hot Springs town.