Giant's kettle

Potholes are cup-or shaft-like depressions in rocks ( scours ) caused by flowing water in the range of glacial ice.

Formation

Potholes formed by melt water that flows through the crevasses and moulins particular to the glacier bed down. This melt water combines to form streams and forms at certain points vertebrae. In these vortices prevail flow rates of up to 200 km / h and high pressure. The main erosion work with hollowing out the rock bed make this the entrained sand and gravel particles. The theory that a rotating boulder in the water mills the pothole like a mill stone from the rock, is deprecated. Primary is the point of impact of a glacier mill, or local vortices in the base current of the subglacial water.

Occurrence

The largest glacial potholes are found naturally where there are many and large glaciers or were. In Europe, this is particularly in Scandinavia and in the Alps and their foreland of the case. Many of these forms come from the Ice Age.

In the Alps, potholes are common, examples can be found about the Glacier Garden Lucerne, the Glacier Garden of Weissbach on the Alpine Road in which these washouts have a diameter of up to a meter or in the community Weiler im Allgäu, where a well-preserved pot was discovered in 1911 during road construction. In North Germany, potholes the last ice ages can be found, for example, in the rock garden of Gommern in Saxony- Anhalt. In the quartzite quarries in the early 19th century were discovered several potholes and given to the Natural History Museum Magdeburg.

In the center of Bad Gastein in Austria several potholes are on display, including an oval in shape with diameters of 4.5 to 5.5 meters and a depth of 5 to 6 meters.

In the Finnish Hiidenkirnut near Askola the largest glacier pot has a diameter of four and a depth of ten meters.