July 21-24, 1871 No. 218. LARGE SPRING UPON SUMMIT, near the outer margin of the main terrace, supplying the above bathing-pools with their water. Its dimensions are twenty-five by forty feet. William Henry Jackson; Catalog #20688d
Photograph by Yellowstone National Park
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. 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.
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