Drumlins

Drumlins are elongated, teardrop-shaped hills formed by the movement of glaciers. They are common in areas that were covered by ice sheets during the last ice age. Drumlins are typically composed of glacial till, which is unsorted and unstratified sediment that was deposited by the glacier as it moved and melted.

Formation of Drumlins

Drumlins form under the ice of a moving glacier. As the glacier advances, it picks up and carries along large amounts of sediment, including rocks and boulders. As the glacier moves over the landscape, the sediment it carries is deposited in ridges and mounds along the glacier’s path. As the glacier continues to move, these deposits are reshaped into the characteristic teardrop shape of drumlins through a process known as "deformation till." This process involves the sediment being molded and reshaped by the pressure of the moving glacier, resulting in the elongated, streamlined shape of the drumlins.

Characteristics of Drumlins

Drumlins are typically 1-2 kilometers long, 500 meters wide, and 50 meters high. They have a steep, stoss end (the end facing the direction from which the glacier advanced) and a gentler, lee end. Because of their streamlined shape, drumlins indicate the direction of glacial movement, with the stoss end pointing in the direction of glacial advance.

Study Guide

1. What is the composition of drumlins?
2. How are drumlins formed?
3. What is "deformation till" and how does it contribute to the formation of drumlins?
4. Describe the characteristic shape of drumlins and what it indicates about glacial movement.
5. What are the typical dimensions of a drumlin?
6. How can the study of drumlins provide information about past glacial activity?