Per Wikipedia Mammoth Hot Springs is a large complex of hot springs on a hill of travertine in Yellowstone National Park . It was created over thousands of years as hot water from the spring cooled and deposited calcium carbonate (over two tons flow into Mammoth each day in a solution). Palette Springs has two distinct faces. This one is a mounded slope of different colors festooned with old trees that were not able to survive this harsh, but beautiful, environment. Steam is rising in the background.