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A giant's kettle, also known as either a giant's cauldron, moulin pothole, or glacial pothole, is a typically large and cylindrical
Giant's kettles are common in
A giant's kettle, also known as either a giant's cauldron, moulin pothole, or glacial pothole, is a typically large and cylindrical pothole
A pothole is a pot-shaped depression in a road surface, usually asphalt pavement, where traffic has removed broken pieces of the pavement. It is usually the result of water in the underlying soil structure and traffic passing over the affecte ...
drilled in solid rock
Rock most often refers to:
* Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids
* Rock music, a genre of popular music
Rock or Rocks may also refer to:
Places United Kingdom
* Rock, Caerphilly, a location in Wale ...
underlying a glacier either by water descending down a deep moulin or by gravel
Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone.
Gr ...
rotating in the bed of subglacial meltwater stream.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. The interiors of potholes tend to be smooth and regular, unlike a plunge pool
A plunge pool (or plunge basin or waterfall lake) is a deep depression in a stream bed at the base of a waterfall or Shut-in (river), shut-in. It is created by the erosion, erosional forces of cascading water on the rocks at the formation's bas ...
.
Formation
Giant's kettles are formed while abedrock
In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...
surface is covered by a glacier. Water, produced by the thawing of the ice
Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...
and snow
Snow consists of individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes.
It consists of frozen crystalline water througho ...
, forms stream
A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...
s on the surface of the glacier, which, having gathered into their courses a certain amount of morainic debris, finally flow down a crevasse
A crevasse is a deep crack that forms in a glacier or ice sheet. Crevasses form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid pieces above a plastic substrate have different rate ...
as a swirling cascade
Cascade, or Cascading may refer to:
Science and technology Science
* Air shower (physics), a cascade (particle shower) of subatomic particles and ionized nuclei
** Particle shower, a cascade of secondary particles produced as the result of a high ...
or moulin. The sides of the crevasse are abraded, and a vertical shaft is formed in the ice. The erosion
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
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
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...
, or boulder
In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In ...
s. Such cavities and pipes afford valuable evidence as to the former extent of glaciers.
Similar potholes are encountered in riverbeds and the Channeled Scablands
The Channeled Scablands are a relatively barren and soil-free region of interconnected relict and dry flood channels, coulees and cataracts eroded into Palouse loess and the typically flat-lying basalt flows that remain after cataclysmic floods ...
scoured by glacial outburst flood
In geomorphology, an outburst flood—a type of megaflood—is a high-magnitude, low-frequency catastrophic flood involving the sudden release of a large quantity of water. During the last deglaciation, numerous glacial lake outburst floods were ...
s.
Locations and notable examples
Giant's kettles are common in Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
(''gletschertopf''; glacier pot), Sweden
Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
(''jättegryta''), Finland
Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...
(''hiidenkirnu''; hiisi
Hiisi (; plural ''hiidet'' ) is a term in Finnic mythologies, originally denoting sacred localities and later on various types of mythological entities.
In later, Christian-influenced folklore, they are depicted as demonic or trickster-like ent ...
's churn), and Moss Island
Moss Island is an island in Little Falls, New York, located between the Mohawk River and the New York State Barge Canal. It is composed of an igneous intrusion of syenite, and became an island when canal locks were built so boats could avoi ...
in the United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
.
In Sweden, they are found in relatively large numbers along the Bohuskusten as well as in the Stockholm area, and in Blekinge
Blekinge () is one of the traditional Swedish provinces (), situated in the southern coast of the geographic region of Götaland, in southern Sweden. It borders Småland, Scania and the Baltic Sea. It is the country's second-smallest provin ...
. For example, a giant pot can be seen under glass in the foundation of Solna's old courthouse in Hagaparken. There are also a number of giant pots on the island of Blå Jungfrun in northern Kalmarsund outside Oskarshamn
Oskarshamn is a coastal city and the seat of Oskarshamn Municipality, Kalmar County, Sweden with 17,258 inhabitants in 2010.
History
Etymology
Döderhultsvik was the original name before a town charter was granted in 1856. The name was then chan ...
.
The Brobacka Nature Reserve, 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 over Lake Mjörn.
''Helvete'' in Gausdal
Gausdal is a municipality in Innlandet county, Norway. It is located in the traditional district of Gudbrandsdal. The administrative centre of the municipality is the village of Segelstad bru. Other villages in Gausdal include Follebu, Forse ...
, Norway
Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...
is a gill
A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...
about 100 meters deep with giant's kettles (''jettegryter'') up to wide and deep. The GletscherGarten of Lucerne
Lucerne ( ) or Luzern ()Other languages: ; ; ; . is a city in central Switzerland, in the Languages of Switzerland, German-speaking portion of the country. Lucerne is the capital of the canton of Lucerne and part of the Lucerne (district), di ...
(Switzerland
Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
) is famous for its giant's kettles, having 32 in number, the largest being wide and deep.
Another example is the large pothole found in Archbald, Pennsylvania, in Archbald Pothole State Park.
See also
* Pothole (disambiguation) *Sinkhole
A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are also known as shakeholes, and to openings where surface water ...
References
*External links
{{Authority control Glaciology Fluvial landforms