All of us spent one day touring Yellowstone. We first visited Mammoth Springs, about fifty miles from Cooke City. The main attraction in the Mammoth Springs area is the terraces. This is an ever changing landscape as the terraces grow and transform by the deposition of travertine. The formations and colors were really interesting!

A description from the nps.gov website on how the terraces are formed:

As ground water seeps slowly downward and laterally, it comes in contact with hot gases charged with carbon dioxide rising from the magma chamber. Some carbon dioxide is readily dissolved in the hot water to form a weak carbonic acid solution. This hot, acidic solution dissolves great quantities of limestone as it works up through the rock layers to the surface hot springs. Once exposed to the open air, some of the carbon dioxide escapes from solution. As this happens, limestone can no longer remain in solution. A solid mineral reforms and is deposited as the travertine that forms the terraces.