Travertine at Mammoth Hot Springs
Yellowstone National Park, Wyoming, USA
Travertine is a form of limestone deposited by mineral springs, especially hot springs. It is formed by a process of rapid precipitation of calcium carbonate at the mouth of the hot spring.
The classic fibrous appearance of the travertine at Mammoth Hot Springs with its array of white, tan, rusty and cream-colors can be seen in this image.