Minerva Terraces-Mammoth Hot Springs. Yellowstone Park.

You see in the view a mass of deposit forty feet high, covering an area of three-quarters of an acre, with a hot spring on its summit, the temperature of which is 154 degrees Fahrenheit. The constant changing of the overflow makes it impossible to predict a season in advance which will be the active side of the terrace or whether it will be active at all. At times the spring disappears entirely and the terrace remains inactive for months. Such was the case at the time this view was taken. Mammoth Hot Springs Hotel and the United States Weather Bureau are in the background.