Giants kettle

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Giants kettle, also known as giants cauldrons or potholes, are cavities or holes which appear to have been drilled in the surrounding rocks by eddying currents of water-bearing stones, gravel and other detrital matter. The size varies from a few inches to several feet in depth and diameter. The commonest occurrence is in regions where glaciers exist or have existed; a famous locality is the GletscherGarten of Lucerne, where there are 32 giants kettles, the largest being 8 m (26 ft) wide and 9 m (30 ft) deep; they are also common in Germany, Norway, Sweden, Finland (locally called hiidenkirnu, hiisi's churn) and in the United States. It appears that 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, are finally cast 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. The erosion may be continued into the bed of the glacier; and, the ice having left the district, the giants kettle so formed is seen 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. Similar holes are met with in riverbeds at the foot of cascades, and under some other circumstances. The term pothole is also sometimes used synonymously with swallow-hole.

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.