Yellowstone National Park – Photos of Artists Paint Pots area Posted on September 8, 2012 by Carol A boiling spring Distant view A steaming vent Close-up of a simmering spring. The colors are caused by iron oxide and cyanobacteria. Boiling mud pot Share this:PrintMoreDiggFacebookLinkedInPinterestStumbleUponRedditEmailTwitterGoogle +1TumblrLike this:Like Loading...