Final answer:
A kettle lake is a depression formed from a melting block of ice after being covered by glacial drift, which may fill with water to form a lake. It is not associated with other glacial depositional features such as eskers, moraines, or erratic boulders.
Step-by-step explanation:
A kettle lake is a feature of glaciation deposition typically formed when a block of ice that was buried in glacial drift melts leaving behind a circular depression. Over time this depression may fill with water, creating a lake. Kettle lakes are not formed by long ridges of gravel and sand (which describes eskers) nor a hill of debris left by a retreating glacier (that would be a moraine), nor by large boulders deposited by glacial ice (known as erratics). Glacial deposition creates various landforms and sediment patterns. Sediments deposited by glaciers are typically poorly sorted with variable grain sizes due to the ice's ability to carry a mixture of everything from fine silts to large rocks.
As the glacier retreats or melts, this mixed material is dropped, or deposited, creating the landscapes we observe. For example the Aletsch Glacier in Switzerland has greatly shaped its surrounding terrain.