{{about|potholes|the 2023 film|Giant's Kettle (film)}} {{Short description|Hole drilled in the rock by Eddy currents of water bearing gravel}} {{Other uses|Pothole (disambiguation)}} [[File:Glacial pothole WI.jpg|thumb|Glacial pothole in Taylors Falls on the St. Croix River at Interstate State Park, Wisconsin, U.S.]]
A '''giant's kettle''', also known as either a '''giant's cauldron''', '''moulin pothole''', or '''glacial pothole''', is a typically large and cylindrical pothole drilled in solid rock underlying a glacier either by water descending down a deep moulin or by gravel rotating in the bed of subglacial meltwater stream.<ref name="NeuendorfOthers2005a">Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. {{ISBN|0-922152-76-4}}</ref> The interiors of potholes tend to be smooth and regular, unlike a plunge pool.{{fact|date=June 2024}}
==Formation== thumb|Illustration of a giant's kettle being formed by rotating gravel thumb|Collection of pebbles shaped in giant's kettles Giant's kettles are formed while a bedrock surface is covered by a glacier. Water, produced by the thawing of the ice and snow, forms streams on the surface of the glacier, which, having gathered into their courses a certain amount of morainic debris, finally flow down a crevasse as a swirling cascade or moulin. The sides of the crevasse are abraded, and a vertical shaft is formed in the ice.<ref name="MAS-112">{{cite journal|journal=Bulletin of the Massachusetts Archaeological Society|date=July 1953|volume=XIV|issue=4|pages=112|url=http://library.bridgew.edu/exhibits/BMAS/pdf/MAS-v14n04.pdf|accessdate=12 July 2010|title=Archived copy|archive-url=https://web.archive.org/web/20160130113119/http://library.bridgew.edu/exhibits/BMAS/pdf/MAS-v14n04.pdf|archive-date=30 January 2016|url-status=dead}}</ref> The erosion may be continued into the bed of the glacier. After the ice departed the area, the giant's kettle formed as an empty shaft, or as a pipe filled with gravel, sand, or boulders. Such cavities and pipes afford valuable evidence as to the former extent of glaciers.{{sfn|Chisholm|1911}}
Similar potholes are encountered in riverbeds and the Channeled Scablands scoured by glacial outburst floods.<ref name=Baker>{{cite book|last1=Baker|first1=Victor|editor1-last=Migon|editor1-first=Piotr|title=Channeled Scablands: A Megaflood Landscape, in Geomorphological Landscapes of the World|date=2010|publisher=Springer|isbn=9789048130542|pages=21–28}}</ref>
== Locations and notable examples == [[File:Hiidenkirnut.jpg|thumb|Giant's kettle in Rovaniemi, Finland]]
Giant's kettles are common in Germany (''gletschertopf''; glacier pot), Sweden (''jättegryta''), Finland (''hiidenkirnu''; hiisi's churn), and Moss Island in the United States.{{sfn|Chisholm|1911}}
In Sweden, they are found in relatively large numbers along the Bohuskusten as well as in the Stockholm area, and in Blekinge.{{fact|date=June 2024}} For example, a giant pot can be seen under glass in the foundation of Solna's old courthouse in Hagaparken.<ref name="MAS-112" /> There are also a number of giant pots on the island of Blå Jungfrun in northern Kalmarsund outside Oskarshamn.{{fact|date=June 2024}} The Brobacka Nature Reserve, Sweden, located outside Alingsås between the lakes Mjörn and Anten, contains one of the country's most impressive areas with giant's kettles, boasting around forty excavations, where the largest one, with its {{convert|18|m}} diameter, stands out. The giant's kettles can be accessed via the Brobacka Nature Center, and the location offers views over Lake Mjörn.{{fact|date=June 2024}}
''Helvete'' in Gausdal Municipality, Norway, is a gill about {{convert|100|m}} deep with giant's kettles ({{langx|no|jettegryter}}) up to {{convert|20|m|abbr=on}} wide and {{convert|60|m|abbr=on}} deep.<ref>{{cite web |last1=Mæhlum |first1=Lars |title=Helvete (elvegjel i Gausdal) |url=https://snl.no/Helvete_-_elvegjel_i_Gausdal |website=Store norske leksikon |date=15 February 2021 |access-date=23 April 2022}}</ref> The GletscherGarten of Lucerne (Switzerland) is famous for its giant's kettles, having 32 in number, the largest being {{convert|8|m|abbr=on}} wide and {{convert|9|m|abbr=on}} deep.<ref name="Uphamt1900a">{{cite journal|last1=Upham |first1=W. |year=1900|title=Giants’ kettles eroded by moulin torrents|journal=Bulletin of the Geological Society of America|volume=12|issue=1|pages=25-44|doi= |pmid= }}</ref>
Another example is the large pothole found in Archbald, Pennsylvania, in Archbald Pothole State Park.<ref name="McGladeOthers2016a">{{ cite web | url = http://www.docs.dcnr.pa.gov/cs/groups/public/documents/document/DCNR_20032581.pdf | last = McGlade | first = William G. | year = 1969 | title = Archbald Pothole State Park, Archbald Pothole, Lackawanna County, Trail of Geology 16–003.0 | access-date = February 12, 2023 | publisher = Pennsylvania Department of Conservation and Natural Resources}}</ref><ref name="Stuart2016a">{{ cite web | url = https://elibrary.dcnr.pa.gov/GetDocument?docId=1752513&DocName=TG16-003_GeoGuide_ArchbaldPotholeSP.pdf | last = Reese | first = Stuart O. | year = 2016 | title = Outstanding Geologic feature of Pennsylvania: Archbald Pothole, Lackawanna County, Trail of Geology 16–025.0 | access-date = February 12, 2023 | publisher = Pennsylvania Department of Conservation and Natural Resources}}</ref>
==See also== *Pothole (disambiguation)
==References== {{Reflist}} * {{EB1911|wstitle=Giant's Kettle|volume=11|page=927}}
==External links== Jettegryte
{{Commons category|Giants kettles}}
{{Authority control}} Category:Glaciology Category:Fluvial landforms