The researchers studied how glaciers moved in an area in southwest Sweden during the melting of ice. They looked at the direction of ice movement using marks on rocks, hills of debris, and patterns in the land. In the western part, the ice first melted towards the northeast, then came back from the north, and finally melted to the north. In the eastern part, the ice melted continuously, changing from northeast to north. They also found that certain hills of debris were made by ice sliding down and debris flowing in front of the melting ice. These hills mark the edge of the ice moving back from the north. The researchers also discovered that these hills were formed after a line in the landscape that was thought to be older.