DE-11822828

Look at these colors! No wonder the Grand Prismatic Spring is one of the most visited and photographed attractions of the Yellowstone National Park. It is also the largest hot spring in the United States, and the third largest in the world.

 

DE-11822828, sent by Astrid and Lucy.

Grand Prismatic Spring was noted by geologists working in the Hayden Geological Survey of 1871, and named by them for its striking coloration. Its colors match most of those seen in the rainbow dispersion of white light by an optical prism: red, orange, yellow, green, and blue.

The bright, vivid colors in the spring are the result of microbial mats around the edges of the mineral-rich water. The mats produce colors ranging from green to red; the amount of color in the microbial mats depends on the ratio of chlorophyll to carotenoids and on the temperature gradient in the runoff. In the summer, the mats tend to be orange and red, whereas in the winter the mats are usually dark green. The center of the pool is sterile due to extreme heat.

The deep blue color of the water in the center of the pool results from the intrinsic blue color of water. The effect is strongest in the center of the spring, because of its sterility and depth. - in: wikipedia