Britannica Sources used in this answer

How do drumlins reveal the direction of former glacier movement?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

glacier Perito Moreno Glacier, Los Glaciares National Park, Argentina.

Drumlins are streamlined, elongated hills that serve as indicators of the direction of former glacial movement. Their orientation and shape provide clear evidence of the path taken by an ice sheet or glacier.12

You can determine the direction of ice flow by observing the following features of a drumlin:

Alignment: The long axis of a drumlin is typically aligned parallel to the direction of regional ice flow.12
Stoss and Lee Sides: In profile, the stoss side (the side facing the oncoming ice) is high and steep, while the lee side (the side facing away from the ice) is smooth and tapers gently in the direction of the ice movement.12
Sediment Fabric: The internal composition of the drumlin often exhibits a fabric where the long axes of individual rocks and sand grains are aligned parallel to the direction of the ice flow.2