English: Hot water is the creative force of the terraces. Even though
Mammoth Hot Springs lie north of the caldera ring-fracture system, a fault trending north from Norris Geyser Basin, 21 miles (34 km) away, may connect
Mammoth Hot Springs to the hot water of that system. A system of small fissures carries water upward to create approximately 50 hot springs in the
Mammoth Hot Springs area. Another necessary ingredient for terrace growth is the mineral
calcium carbonate. Thick layers of
sedimentary limestone, deposited millions of years ago by vast seas, lie beneath the Mammoth area. As ground water seeps slowly downward and laterally, it comes in 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, some of the carbon dioxide escapes from solution. As this happens, limestone can no longer remain in solution. A solid mineral reforms and is deposited as the travertine that forms the terraces. (The image caption was taken from
here.)
Français : Hautes terrasses de
Mammoth Hot Springs (Litt. « Les sources chaudes taille mammouth ». Les terrasses (ou plutôt les
gours) de Mammoth hot springs ont une origine géologique assez complexe: Le site de Mammoth hot springs ne se trouve pas dans la Caldeira de
Yellowstone, mais sur un substrat sédimentaire
Calcaire. De l'eau chaude provenant du bassin de Norris situé à 34 km de là circule vers cette zone via un système de failles orientées nord-sud. Cette eau est chargée en
Acide carbonique, ce qui lui confère la propriété de dissoudre le calcaire. Lorsque l'eau chaude chargée en calcaire émerge, une partie de l'acide carbonique s'évapore sous forme de dioxyde de carbone, et une partie du calcaire précipite, formant de gigantesques gours.