Esker vs. Drumlin — What's the Difference?

Eskers form from sediment deposition within subglacial or englacial streams, creating elongated, sometimes snaking ridges that can extend for miles. These ridges are typically found in previously glaciated regions, marking the path of meltwater streams beneath or within glaciers. On the other hand, drumlins are shaped by the movement of glaciers over an underlying substrate, with their long axis aligned in the direction of ice flow. They are made primarily of till, a mixture of clay, silt, sand, and gravel that was deposited directly by glacier ice.

Eskers are notable for their linear form, which can provide insight into the direction of glacial meltwater flow. Their formation requires a steady supply of meltwater, making their presence an indicator of past glacial activity and the dynamics of ice retreat. Drumlin fields, or groups of drumlins, can indicate the flow direction of ice sheets and are often found in clusters, revealing patterns of ice movement across the landscape.

The study of eskers and drumlins contributes to our understanding of glacial processes and the shaping of Earth's surface. Eskers, with their confined routes of formation, tell a story of water flow beneath ice, while drumlins give clues about the overarching movement of glaciers themselves, offering a larger-scale perspective on glacial dynamics.

While eskers serve as a record of subglacial water paths, drumlins provide evidence of the glacier's shape and movement, reflecting different aspects of glacial behavior. Their distinct forms and compositions are key to reconstructing past glacial environments and understanding the geological history of an area.