MAMMOTH HOT SPRINGS AREA
YELLOWSTONE NATIONAL PARK
WELCOME to the Mammoth Hot Spring Terraces,one of Yellowstone’s fascinating natural features! Thereare several ways to enjoy the terraces—hike the boardwalksor drive the Upper Terrace Loop road, for example.You may wish to drive to the Upper Terrace Loop,drop off members of your party, let them hike down theboardwalk and pick them up at the lower parking area.The maps in this pamphlet will help you decide how youmight best enjoy the terraces.
The Mammoth Terraces and Hot Springs were officiallydiscovered by a U.S. Geological Survey party led by Dr.Ferdinand Hayden in 1871. However, some local knowledgeof the Hot Spring Terraces and their activity had existedprevious to that time.
The Mammoth Hot Springs have interested people sincethe establishment of Yellowstone National Park, not onlyfor their striking beauty but also their changeability. Theseremarkable springs are noted for their rapid deposition,unpredictable shifts, and random rejuvenation. Here theactive forces of geology often make measurable changesfrom one day to the next, and it is possible that significantchanges have occurred since this booklet was printed.
INGREDIENTS FOR HOT SPRINGS ACTIVITY
Hot water is the life of the terraces. Without it terracegrowth ceases; the formations weather gray and black,and begin to crumble. Typically the many hot springsgush forth at random, flow a short way, then disappearinto a crack or fissure farther down slope.
In searching around the Mammoth area old dormant terracemounds can be found in several places. Although afrequent shifting seems to take place, the records over thepast several years indicate that the total flow of water hasremained fairly constant at some 500 gallons per minute.
Ground water is the source of the outflow at MammothHot Springs. It is mostly seepage fed by rain and snowfalling high on the slopes of Terrace Mountain and areasas far south as Norris Geyser Basin. This cold groundwater is heated before it emerges to the surface by risingheat from the magma chamber which once fueled theviolent volcanos of Yellowstone’s past. See the diagramon the reverse of this leaflet. The water temperature inthese springs reaches the vicinity of 170 F (73 C.)
Yet still another ingredient is needed for growth of the terraces—thatis, a basic building material. The raw materialhere is calcium carbonate. It is abundant beneath TerraceMountain as thick layers of sedimentary limestone.Related layers of limestone are visible as outcrops on theface of Mt. Everts across the narrow valley to the east.
Different temperature zonesin the water channels paintribbons of algal color.
As the ground water seeps slowly downward into thelimestone it comes in contact with hot gases rising fromthe magma chamber which are heavily charged with carbondioxide. Some of the carbon dioxide is readily absorbedto form a carbonic acid solution. Ordinarily watercan only slowly dissolve limestone, but the hot, acidicsolution rapidly dissolves great quantities of it. Saturatedwith lime, the carbonated water continues to seep alongthe ro