Canary Spring, Mammoth Hot Springs, Yellowstone NP. Named for bright yellow color caused by sulfur dependent bacteria on the white calcium carbonate. The colors blend in delicate tints on the creamy rock face. The hot Calcium Carbonate ladened water flows out of the spring and as it cools deposits the minerals as it goes. Many times this envades forest area (like here), kills the trees and as the level of the deposits rise, only the skeletal tops of the trees remain.