[3] 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).

[4] 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[5] that runs through limestone and roughly parallel to the Norris-to-Mammoth road.

[6][7] Shallow circulation along this corridor allows Norris's superheated water to slightly cool before surfacing at Mammoth, generally at about 170 °F (80 °C).

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.