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Mammoth Hot Springs: Eccentric Beauty Outside the Yellowstone Caldera

Mammoth Hot Springs in Yellowstone National Park, Wyoming is a limestone mountain with bubbling waters and colorful terraces that formed over a period of hundreds of years. They change every day so there’s always something new for the park’s two million annual visitors.

Text and photos: Javier A. Pinzón


Yellowstone is made up of a series of wild and weird landscapes that evoke the Earth’s origins and its probable end. These unique places sit on top of the caldera of an active volcano hidden beneath the Earth’s surface. However, not all of the park’s natural phenomena are located on top of the crater; Mammoth Hot Springs is one example.

Mammoth Hot Springs, which has its own story to tell, sits northeast of this National Park in the state of Wyoming. The lively limestone mountain, with bubbling waters and colorful terraces, formed over a period of hundreds of years. It changes every day so there’s always something new for the two million visitors who walk its paths every year.

At first glance this looks like a small spring of turquoise waters, but it is here that an underground stream meets the surface after traveling along the Morris-Mammoth geological fault through a network of underground limestone canals. The water, with temperatures exceeding 100° C, rises to the surface, bringing a high concentration of dissolved calcium carbonate with it.

Most of the water evaporates when it reaches the surface, releasing carbon dioxide gases. The carbonate combines with calcium to become travertine, the white porous rock characteristic of this landscape. The water cools down as it moves along, leaving behind a trail of crystallized calcium carbonate that forms the small stalactites under the waterfalls.

When the water flow and temperature are constant, bacteria and algae adapted to high temperatures colonize the terraces and color the landscape yellow, red, and brown. They are living carpets in inhospitable environments.

The newly created travertine is bright white: under the sun’s rays it looks like a solid snowy surface surrounded by boiling water. Over time, the water stops flowing and the travertine turns gray. The once bright landscape becomes dull and bleak

As the water drops and cools, the small pools formed by the accumulation of calcium carbonate transform into terraces, which look like steps from a distance.

This is an active process. Small geological shifts divert the flow of water and the terraces are activated and deactivated, drying up and undergoing constant changes in shape and color, which creates a dégradé effect downhill.

To accommodate changes in the water’s course, the park maintains a mile of open roads and bridges, depending on the time of year. This way, visitors can walk over this wonder and appreciate it without damaging it. A drive along this circuit leads to the upper terraces.

This natural wonder isn’t the only tourist attraction: the meadows around the hot waterfalls are full of wildlife that feeds on algae growing there. Elk, deer, bison, wolves, and foxes take advantage of nutrients during the summer and the high temperatures of the springs during winter.

Mammoth Hot Springs is one of the Yellowstone volcano’s hundreds of geothermal phenomena. The Grand Canyon of the Yellowstone, with waterfalls up to 300 feet high, more than three hundred geysers, hot turquoise pools, bubbling mud, and an abundance of large mammals, all make this the perfect place to enjoy a unique experience that reminds us of the Earth’s origins and allows us to imagine its end.

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