形成阶地一大要素就是碳酸钙。几百万年前马姆莫斯地区底部的海水，为这里留下了厚质的沉淀性石灰石。当高温的酸性溶液流经岩石层到达温泉表面的过程中，它溶解了大量的沉淀性石灰石。一遇到空气，溶液中的部分二氧化碳就会从溶液中挥发。同时固体矿物质形成并最终以石灰华形式沉淀，就形成了阶地。远远望去堆金积玉、晶莹剔透，留下的热泉沿着山坡形成一个一个非常漂亮的五彩大台阶，同样的景色让人不由想到我们中国四川黄龙的五彩池。不一样的是，黄龙是冷泉，猛犸是热泉 。
黄石公园黄石公园地底热能出现异常现象，这座“超级火山”已经显现爆发的先兆。
2009年7月23日以来，黄石公园关闭了园内部分地区。官方的解释是，黄石公园地底热能出现异常现象，担心溢出灼伤游人。8月7日，美国地质勘探局内部报告称，美国科学家将在公园内安装临时地震检测网络、全球定位系统接收仪和高灵敏测热液温度器等。3天后，《丹佛邮报》称，美地质勘探局地质学家利兹发现黄石湖的湖床底部隆起了一个高30多米、长600多米的“大包”。8月24日，美国犹他州大学地震站测到公园南门东南15公里处的地底，发生了4.4级的地震，这次地震“非同寻常”，震源离地面仅0.834公里!为此，美、英地质专家发出警告，黄石公园地底热能出现异常现象，很可能正是该处“超级火山”即将苏醒的先兆!
Mammoth Hot Springs is a large complex of hot springs on a hill of travertine in Yellowstone National Park adjacent to Fort Yellowstone and the Mammoth Hot Springs Historic District. It was created over thousands of years as hot water from the spring cooled and deposited calcium carbonate (over two tons flow into Mammoth each day in a solution). Because of the huge amount of geothermal vents, travertine flourishes. Although these springs lie outside the caldera boundary, their energy has been attributed to the same magmatic system that fuels other Yellowstone geothermal areas.
The hot water that feeds Mammoth comes from Norris Geyser Basin after traveling underground via a fault line that runs through limestone and roughly parallel to the Norris-to-Mammoth road. The limestone from rock formations along the fault is the source of the calcium carbonate. Shallow circulation along this corridor allows Norris' superheated water to slightly cool before surfacing at Mammoth, generally at about 170 °F (80 °C). Algae living in the warm pools have tinted the travertine shades of brown, orange, red, and green.
Thermal activity here is extensive both over time and distance. The thermal flows show much variability with some variations taking place over periods ranging from decades to days. Terrace Mountain at Mammoth Hot Springs is the largest known carbonate-depositing spring in the world. The most famous feature at the springs is the Minerva Terrace, a series of travertine terraces. The terraces have been deposited by the spring over many years but, due to recent minor earthquake activity,[when?] the spring vent has shifted, rendering the terraces dry.
The Mammoth Terraces extend all the way from the hillside, across the Parade Ground, and down to Boiling River. The Mammoth 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. Several large sink holes (fenced off) can be seen out on the Parade Ground. This area has been thermally active for several thousand years.
The Mammoth area exhibits much evidence of glacial activity from the Pinedale Glaciation. The summit of Terrace Mountain is covered with glacial till, thereby dating the travertine formation there to earlier than the end of the Pinedale Glaciation. Several thermal kames, including Capitol Hill and Dude Hill, are major features of the Mammoth Village area. Ice-marginal stream beds are in evidence in the small, narrow valleys where Floating Island Lake and Phantom Lake are found. In Gardner Canyon one can see the old, sorted gravel bed of the Gardner River covered by unsorted glacial till.
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