View source for Grand Prismatic Spring

{{Short description|Largest hot spring in the United States}}
{{Use mdy dates|date=September 2024}}
{{Use American English|date=September 2024}}
{{Infobox hot spring
| name = Grand Prismatic Spring
| photo = Aerial image of Grand Prismatic Spring (view from the south).jpg
| photo_width = 
| photo_caption = Aerial view of the Grand Prismatic Spring
| location = [[Geothermal areas of Yellowstone#Midway Geyser Basin|Midway Geyser Basin]], [[Yellowstone National Park]], [[Teton County, Wyoming]]
| coordinates = {{Wikidatacoord|Q1422831|region:US-WY_type:waterbody|display=inline,title}}
| coords_ref = <ref>{{cite rcn|5748|Grand Prismatic Spring }}</ref>
| elevation = {{cvt|7270|ft}}<ref>{{cite gnis|1609256|Grand Prismatic Spring }}</ref>
| hot_spring_type = [[Hot spring]]
| height = 
| duration = 
| frequency = 
| discharge = {{cvt|560|USgal|L|-2}} per minute
| temperature = {{cvt|160|F|C|-1}}
| depth = {{cvt|160|ft|m|-1}}
}}
The '''Grand Prismatic Spring''' in [[Yellowstone National Park]] is the largest [[hot spring]] in the United States, and the third largest in the world,<ref>{{cite web |title=Steam Explosions, Earthquakes, and Volcanic Eruptions—What's in Yellowstone's Future? |publisher=U.S. Geological Survey |url=http://pubs.usgs.gov/fs/2005/3024/ |access-date=September 14, 2005 |archive-date=July 23, 2018 |archive-url=https://web.archive.org/web/20180723093212/https://pubs.usgs.gov/fs/2005/3024/ |url-status=live }}</ref> after [[Frying Pan Lake]] in New Zealand and [[Boiling Lake]] in Dominica. It is located in the [[Geothermal areas of Yellowstone#Midway Geyser Basin|Midway Geyser Basin]].

Grand Prismatic Spring was noted by geologists working in the [[Hayden Geological Survey of 1871]], and named by them for its striking coloration. Its colors match most of those seen in the [[rainbow]] dispersion of white light by an optical [[Prism (optics)|prism]]: red, orange, yellow, green, and blue.<ref>{{Cite web |url=http://www.lpi.usra.edu/education/fieldtrips/2007/explorations/grand_prismatic/index.html |title=Grand Prismatic Spring |author1=Traci Bryan |author2=Leslie Machen |author3=Joyce Heinsz |author4=Peggy McCracken |publisher=Lunar and Planetary Institute |access-date=December 4, 2015 |archive-date=March 3, 2016 |archive-url=https://web.archive.org/web/20160303214633/http://www.lpi.usra.edu/education/fieldtrips/2007/explorations/grand_prismatic/index.html |url-status=live }}</ref>

==History==

The first records of the spring are from early European explorers and surveyors. In 1839, a group of four trappers from the [[American Fur Company]] crossed the Midway Geyser Basin and made note of a "boiling lake", most likely the Grand Prismatic Spring,<ref>{{cite book |chapter="The Fire Hole": Era of the American Fur Company, 1833-1840 |title=Colter's Hell & Jackson's Hole |chapter-url=http://www.cr.nps.gov/history/online_books/grte1/chap7.htm |publisher=[[National Park Service]] |url-status=dead |archive-url=https://web.archive.org/web/20050312032047/http://www.cr.nps.gov/history/online_books/grte1/chap7.htm |archive-date=March 12, 2005 }}</ref> with a diameter of {{convert|300|ft|m|-1}}. In 1870 the [[Washburn–Langford–Doane Expedition]] visited the spring, noting a {{convert|50|ft|m|adj=on}} [[geyser]] nearby (later named [[Excelsior Geyser|Excelsior]]).<ref>{{cite book |chapter=Notes |title=Yellowstone National Park: Its Exploration and Establishment |chapter-url=http://www.cr.nps.gov/history/online_books/haines1/ieee.htm#2146 |publisher=National Park Service |url-status=dead |archive-url=https://web.archive.org/web/20060208011441/http://www.cr.nps.gov/history/online_books/haines1/ieee.htm#2146 |archive-date=February 8, 2006 }}</ref><ref>{{cite book |chapter=Part II: Definitive Knowledge - The Washburn Party (1870) |title=Yellowstone National Park: Its Exploration and Establishment |publisher=National Park Service |chapter-url=http://www.cr.nps.gov/history/online_books/haines1/iee2d.htm |url-status=dead |archive-url=https://web.archive.org/web/20041213044126/http://www.cr.nps.gov/history/online_books/haines1/iee2d.htm |archive-date=December 13, 2004 }}</ref>

==Color==

The bright, vivid colors in the spring are the result of [[microbial mat]]s of [[Thermophile|thermophilic]] 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 of [[chlorophyll]] to [[carotenoid]]s 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.<ref>{{cite web |author=Thomas D. Brock |author-link=Thomas D. Brock |title=Colorful Yellowstone |work=Life at High Temperature |url=http://www.bact.wisc.edu/bact303/b4 |archive-url=https://web.archive.org/web/20051125213458/http://www.bact.wisc.edu/bact303/b4 |archive-date=November 25, 2005 }}</ref>

The deep blue color of the water in the center of the pool results from the [[Color of water|intrinsic blue color of water]]. The effect is strongest in the center of the spring, because of its sterility and depth.<ref name=Geiling/>

==Physical structure==

The spring is approximately {{convert|370|ft|m|-1}} in diameter and is {{convert|160|ft|m|-1}} deep. The spring discharges an estimated {{convert|560|USgal|L|-2}} of {{convert|160|F|C|-1}} water per minute.<ref name=Geiling>{{cite web |last1=Geiling |first1=Natasha |title=The Science Behind Yellowstone's Rainbow Hot Spring |url=http://www.smithsonianmag.com/travel/science-behind-yellowstones-rainbow-hot-spring-180950483/?no-ist |website=Smithsonian.com |publisher=Smithsonian Institution |access-date=August 17, 2015 |archive-date=August 7, 2015 |archive-url=https://web.archive.org/web/20150807201143/http://www.smithsonianmag.com/travel/science-behind-yellowstones-rainbow-hot-spring-180950483/?no-ist |url-status=live }}</ref><ref>{{cite gosa|GRANDPRISMATIC|Grand Prismatic Spring }}</ref>
{{gallery
|width = 250
|File:Grand Prismatic Springs in July.jpg|Grand Prismatic Spring|4=Aerial view of spring|5=File:Grand Prismatic Spring, Yellowstone NP.jpg|6=Microbial mat|7=File:Grand_Prismatic_Spring_(timelapse).webm|8=Timelapse video of the Grand Prismatic Spring}}

==References==
{{Commons category|position=right}}
{{Portal|Volcanoes|Geology|Wyoming|United States}}
{{Reflist}}
{{Lower Midway}}
{{Wyoming}}

[[Category:Geothermal features of Yellowstone National Park]]
[[Category:Hot springs of Wyoming]]
[[Category:Geothermal features of Teton County, Wyoming]]
[[Category:Hot springs of Teton County, Wyoming]]