rainbow in grand canyon of the yellowstone

active activity america attraction autumn background bacteria basin big black blue bright caldera canyon castle cloudy colorful cone day detail emblem eroded erosion evening fire flow geologic geothermal geyser grand grey hot irregular landscape large loop midway mineral montana national nature orange outdoors park pool pools predictable prevision prismatic rainbow rainy rock sand sandstone sky smoke spout spring steam steaming storm sunset tree trees unpredictable upper usa volcano waterfall waterfalls wide wyoming yellowstone