Tepee Fountain was built in 1909 to vent steam from hot mineral water that was piped throughout the park. As water flows over the structure, it cools and deposits layer upon layer of travertine, a process similar to the formation of terraces seen throughout the park. The different colors on the fountain come from various types of algae that grow in the hot mineral water. The earliest photo of Tepee Fountain shows water flowing out of a vertical vent pipe over a pyramid of rocks, and other historical photos show the buildup of mineral deposits over time.