Orange Spring Mound in the Mammoth Hot Springs Complex, Yellowstone National Park, Wyoming. It was created by deposits of thermophilic cyanobacteria, calcium carbonate, and algae resulting from very slow water flow and mineral deposits. Color changes occur during different seasons depending on the water flow rate and the amount of sunlight available. The spring that feeds this mound is cooler at 157 degrees than other thermal features in the area. This allows the bacteria to be more pronounced.