Mammoth Hot Springs Terraces
As one early visitor described the Mammoth Hot Springs terraces, "No human architect ever designed such intricate fountains as these. The water trickles over the edges from one to another, blending them together with the effect of a frozen waterfall." The hot springs were an early commercialized attraction for those seeking relief from ailments in the mineral waters.
Mammoth Hot Springs are a surface expression of the deep volcanic forces at work in Yellowstone. Although these springs lie outside the caldera boundary, scientists surmise that the heat from the hot springs comes from the same magmatic system that fuels other Yellowstone thermal areas. A large fault system runs between Norris Geyser Basin and Mammoth, which may allow thermal water to flow between the two. Also, multiple basalt eruptions have occurred in this area. Thus, basalt may be a heat source for the Mammoth area.
Thermal activity here is extensive and has been present for several thousand years. Terrace Mountain, northwest of Golden Gate, has a thick cap of travertine. The Mammoth Hot Springs Terraces extend all the way from the hillside where we see them today, across the historic Parade Ground, and down to Boiling River. The Mammoth Hot Springs Hotel, as well as all of Fort Yellowstone, is built upon an old terrace formation known as Hotel Terrace. There was some concern when construction began in 1891 on the fort site that the hollow ground would not support the weight of the buildings. Currently, there are several large sinkholes (fenced off) can be seen on the Parade Ground.
