Taking its ﬁgurative cue from the domestic vessel for boiling water, similar to a pot or cauldron, the geological kettle refers to a hollow scoured in a rocky riverbed or under a glacier. Kettles are often found embedded in moraines. They are formed by depressions left by the melting of an ice block lodged in a deposit of till or drift. Sometimes known as potholes or sinks, these cavities can be of irregular size and depth and are often numerous in glacial regions. Kettle hole is a synonym. Kettle Hole Woods State Natural Area in Wisconsin is a good example of this topography, as is the Kettle Hole Trail in Long Island, New York. Thoreau’s Walden Pond is another example. Places where especially large kettle holes are ﬁlled with water are called kettle lakes.