kettle
A depression in glacial outwash formed when a block of ice left behind by a retreating glacier is buried in sediment and eventually melts, leaving a hole. Kettles often fill with water to become kettle lakes or kettle ponds — small, round, self-contained bodies of water with no inlet or outlet, sitting in the middle of otherwise dry ground. Walden Pond is a kettle.
Etymology
From the shape — a rounded depression, like a cooking kettle pressed into the earth. Not to be confused with the climbing/birding term kettle (raptors circling on a thermal).
Notes
Walden Pond is a kettle lake. Thoreau's most famous landscape feature is a hole left by ice.
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