Mammoth Hot Springs Terraces, Yellowstone National Park
October 12, 2000
Established in 1872, 2.2 million acre Yellowstone National Park receives over 4 million visitors annually. Today's geothermal activity in the park is a link to past volcanism at Yellowstone. A partially molten magma chamber, remnant of a cataclysmic volcanic explosion 600,000 years ago in central Yellowstone, supplies the heat for one of the largest geothermal areas on Earth.
These travertine deposits of the Jupiter Terrace of Mammoth Hot Springs formed from hot water rising through limestone. As ground water seeps slowly downward and laterally, it comes into contact with hot gases charged with carbon dioxide rising from the magma chamber. Some carbon dioxide is readily dissolved in the hot water to form a weak carbonic acid solution. This hot, acidic solution dissolves great quantities of limestone as it works up through the rock layers to the surface hot springs. Once exposed to the open air, limestone can no longer remain in solution. A solid mineral reforms and is deposited as the travertine that forms these spectacular terraces.