Answer: Glacial action
Notes: Most eskers are argued to have formed within ice-walled tunnels by streams which flowed within and under glaciers. They tended to form around the time of the glacial maximum when the glacier was slow and sluggish. After the retaining ice walls melted away, stream deposits remained as long winding ridges.
Drumlin, oval or elongated hill believed to have been formed by the streamlined movement of glacial ice sheets across rock debris, or till. Drumlins are commonly found in clusters numbering in the thousands. Often arranged in belts, they disrupt drainage so that small lakes and swamps may form between them.
