Tower Falls up close and personal.
We've moved on to Mammoth Hot Springs. Standing on the Main Terrace, this shot shows Fort Yellowstone. This Army town is virtually unchanged from when it was really an Army fort between 1886 and 1918. Along the trail is a photo from this time period. Other than the fact that it is black and white, when you look up from the photo, the town looks identical.
This is the Main Terrace. The water emanating from Mammoth Hot Springs becomes charged with carbon dioxide while underground, creating a mild carbonic acid. That acid dissolves underground limestone rocks and carries the mixture to the surface of the Earth. Once on the surface, the carbon dioxide gas escapes. Without carbon dioxide, the water is less able to carry the dissolved limestone. The dissolved limestone precipitates out, creating beautiful travertine terraces.