Rock Formations | Yellowstone’s Orange Spring Mound Located on the Mammoth Hot Springs upper terraces, Orange Mound Spring is cooler than most springs in Yellowstone, which allow the orange-tinted cyanobacteria to live on the travertine, the rock it’s made of. The spring is very old with a very slow water flow rate. The water flows from several vents on its top and side. The flow starts and stops quite often. Some days it does not flow at all. For the whole story with all images, see Rock Formations | a 7 Image Story.
