We might not have known about this new thermal area if it were not for those keeping watchful eyes it's so deep in the back country it took someone combing through satellite photos to discover it.

Yellowstone National Park geologist Jeff Hungerford says it was heat and carbon dioxide rising that tipped them off.

The site grew slowly over 15 years or so before it was seen. Tell-signs include fallen trees and disappearing grass and undergrowth. Then, finally, steam was seen.

According to experts, the thermal is very young and still developing, so we have no idea what this will end up looking like in the long run. Stay tuned over the next few decades to find out.

The ground in the area is hot. In some places it's even soft and it's possible to sink in and get burned.

Here is more information from the U.S. Geological Survey website.

Yellowstone's thermal areas are the surface expression of the deeper magmatic system, and they are always changing. They heat up, they cool down, and they can move around. A recent spectacular example was the September 2018 emergence of a new thermal feature and eruption of the long-dormant Ear Spring in the Upper Geyser Basin, near Old Faithful. Even more impressive was the expansion of heated ground in the Back Basin of the Norris Geyser Basin in 2003. These sorts of changes are part of the normal life cycles of thermal areas in Yellowstone National Park.

Recently, we have discovered another phenomenal example of thermal change—the emergence of an entirely new thermal area, which has taken place over the past 20 years!