Giant's kettle

A giant's kettle, also known as a giant's cauldron or pothole, is a cavity or hole which appears to have been drilled in the surrounding rocks by eddying currents of water bearing stones, gravel, and other detrital matter.

The interiors of potholes tend to be smooth and regular, unlike a plunge pool. An example is the large pothole found in Archbald, Pennsylvania in Archbald Pothole State Park.

Formation

Potholes vary in size from a few inches to several feet in depth and diameter. They most commonly occur in shields, where there are ancient rocks (granite, gneiss) with different resistances to erosion, so strong pebbles can fall into small cavities in stream bottoms and swirl, making the cavities wider and deeper. The hardness of the pebbles must be the same or higher than the rock at the bottom of stream where the kettle is forming. In areas where there are diamonds and quartz pebbles, the hardness of these carve potholes and sometimes remain trapped in the bottom of them.