Kettle (landform)

A kettle, also known as a kettle hole, kettlehole or pothole, and called a pingo in parts of the United Kingdom, is a depression or hole in an outwash plain formed by a retreating glacier or by draining floodwater. A kettle begins when a block of ice, left behind as a glacier retreats, becomes buried in sediment carried by meltwater streams; as the surrounding sediment builds up around the buried ice, the ice eventually melts away, leaving a depression that gives the outwash plain a dimpled appearance, with a rampart sometimes forming around the rim as the ice melts. A kettle no deeper than about ten meters often fills with water to form a kettle hole lake, or with vegetation and sediment over time, producing an acidic kettle bog or an alkaline kettle peatland depending on local water chemistry; a kettle can also form from the sudden drainage of an ice-dammed lake, when the block of ice that had dammed it melts and leaves a similar hole behind.