Hot, steamy water is nature's creative force behind this travertine terrace. Just underfoot is a partially molten magma chamber responsible for all the geothermal activity in Wyoming's Yellowstone National Park. A network of small underground fissures supply steaming water to Mammoth Hot Springs area. Limestone (calcareous tufa) is dissolved below the surface and then deposited on this geological wonder. These terrace features can change their appearance rapidly, offering a different scene year after year.