The Morning Glory Pool in Yellowstone National Park, Wyoming, America, was originally blue, but it has changed colour over the years due to chemical reactions caused by tourists throwing coins into its hot water.
Over the years the coins and other debris blocked the pool’s heat vents, reducing the water’s temperature and causing different types of bacteria to grow, creating a red and yellow ring around the pure blue centre. IT consultant Arun Yenumula, who took the photograph of the pool, sais:
“Each colour represents a different type of heat-seeking algae. An information board next to the pool calls it ‘fading glory’ because people threw rocks, stones, bottles and cans blocking the heat vents at the bottom, resulting in cooling the pool. The bacteria which thrive in real hot water started to die and the colours are fading.”