| Grand Prismatic Spring | |
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.jpg) Aerial view of the Grand Prismatic Spring | |
 Interactive map of Grand Prismatic Spring | |
| Location | Midway Geyser Basin,Yellowstone National Park,Teton County, Wyoming |
| Coordinates | 44°31′30″N110°50′17″W / 44.525°N 110.8381°W /44.525; -110.8381[1] |
| Elevation | 7,270 ft (2,220 m)[2] |
| Type | Hot spring |
| Discharge | 560 US gal (2,100 L) per minute |
| Temperature | 160 °F (70 °C) |
| Depth | 160 ft (50 m) |
TheGrand Prismatic Spring inYellowstone National Park is the largesthot spring in the United States, and the third largest in the world,[3] afterFrying Pan Lake in New Zealand andBoiling Lake in Dominica. It is located in theMidway Geyser Basin.
Grand Prismatic Spring was noted by geologists working in theHayden Geological Survey of 1871, and named by them for its striking coloration. Its colors match most of those seen in therainbow dispersion of white light by an opticalprism: red, orange, yellow, green, and blue.[4]
The first records of the spring are from early European explorers and surveyors. In 1839, a group of four trappers from theAmerican Fur Company crossed the Midway Geyser Basin and made note of a "boiling lake", most likely the Grand Prismatic Spring,[5] with a diameter of 300 feet (90 m). In 1870 theWashburn–Langford–Doane Expedition visited the spring, noting a 50-foot (15 m)geyser nearby (later namedExcelsior).[6][7]
The bright, vivid colors in the spring are the result ofmicrobial mats ofthermophilic bacteria around the edges of the mineral-rich water. The mats produce colors ranging from green to red; the amount of color in the microbial mats depends on the ratio ofchlorophyll tocarotenoids and on the temperature gradient in the runoff. In the summer, the mats tend to be orange and red, whereas in the winter the mats are usually dark green.[8]
The deep blue color of the water in the center of the pool results from theintrinsic blue color of water. The effect is strongest in the center of the spring, because of its sterility and depth.[9]
The spring is approximately 370 feet (110 m) in diameter and is 160 feet (50 m) deep. The spring discharges an estimated 560 US gallons (2,100 L) of 160 °F (70 °C) water per minute.[9][10]
Yellowstone National Park - Lower and Midway Geyser Basins | ||
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Geothermal features, geography, historic structures and other attractions in theLower and Midway Geyser Basins | ||
| Lower Geyser Basin |
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| Midway Geyser Basin | ||
| Structures and history | ||
| Geography and geology | ||
