| Mammoths hot springs lies outside the caldera of Yellowstone, yet heated water travels underground via a fault line running through limestone. Limestone is dissolved by the hot water, which becomes super-saturated in calcium carbonate. Upon surfacing of the hot water in Mammoth hot springs, the water cools down and the dissolved calcium carbonate precipitates to form the so-called travertine. |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
Yellowstone (Wyoming), USA; 17 August 2017. |