North-looking oblique aerial photograph showing about a dozen enlarging depressions forming on the surface of debris-covered stagnant ice in the medial moraine band area of Bering Glacier's piedmont lobe, Chugach National Forest, Chugach Mountains, Alaska. The largest kettle hole shown is about 150 feet in diameter. Bering Glacier flows through Wrangell-Saint Elias National Park. Photo credit: USGS.
A kettle hole is a steep-sided depression formed when a chunk of ice left behind by a receding glacier is covered by rocks and other debris previously pushed forward by the glacier. The ice melts and the rocks fall through, creating a kettle pot-shaped depression. Kettle lakes are water-filled kettle holes.