New Blue Spring is among the Mammoth Hot Springs Terraces in the northwestern part of Yellowstone National Park. The travertine terraces are deposits of calcium carbonate, formed when limestone underneath the terraces is dissolved by mildly acidic heated groundwater, raised to the surface by the hot springs and solidifies there when it is exposed to air. During periods of high flow, individual terracettes can grow rapidly, as much as 8 inches per year.
Steam rises from the travertine terraces of New Blue Spring, part of the Mammoth Hot Springs complex. Yellowstone National Park, Wyoming, USA