Agiant's kettle, also known as either agiant's cauldron,moulin pothole, orglacial pothole, is a typically large and cylindricalpotholedrilled in solidrock underlying a glacier either by water descending down a deepmoulin or bygravel rotating in the bed ofsubglacial meltwater stream.[1] The interiors of potholes tend to be smooth and regular, unlike aplunge pool.[citation needed]
Giant's kettles are formed while abedrock surface is covered by a glacier. Water, produced by the thawing of theice andsnow, formsstreams on the surface of the glacier, which, having gathered into their courses a certain amount ofmorainic debris, finally flow down acrevasse as a swirlingcascade ormoulin. The sides of the crevasse are abraded, and a vertical shaft is formed in the ice.[2] Theerosion 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 apipe filled with gravel,sand, orboulders. Such cavities and pipes afford valuable evidence as to the former extent of glaciers.[3]
Similar potholes are encountered inriverbeds and theChanneled Scablands scoured by glacialoutburst floods.[4]
Giant's kettles are common inGermany (gletschertopf; glacier pot),Sweden (jättegryta),Finland (hiidenkirnu;hiisi's churn), andMoss Island in theUnited States.[3]
In Sweden, they are found in relatively large numbers along the Bohuskusten as well as in the Stockholm area, and inBlekinge.[citation needed] For example, a giant pot can be seen under glass in the foundation of Solna's old courthouse in Hagaparken.[2] There are also a number of giant pots on the island ofBlå Jungfrun in northern Kalmarsund outsideOskarshamn.[citation needed] 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 18 meter diameter, stands out. The giant's kettles can be accessed via the Brobacka Nature Center, and the location offers views overLake Mjörn.[citation needed]
Helvete inGausdal Municipality,Norway, is agill about 100 metres (330 ft) deep with giant's kettles (Norwegian:jettegryter) up to 20 m (66 ft) wide and 60 m (200 ft) deep.[5] The GletscherGarten ofLucerne (Switzerland) is famous for its giant's kettles, having 32 in number, the largest being 8 m (26 ft) wide and 9 m (30 ft) deep.[6]
Another example is the large pothole found inArchbald, Pennsylvania, inArchbald Pothole State Park.[7][8]
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This article incorporates text from a publication now in thepublic domain: Chisholm, Hugh, ed. (1911). "Giant's Kettle".Encyclopædia Britannica. Vol. 11 (11th ed.). Cambridge University Press. p. 927.
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