Map of the sea floor in Antarctica. The long, narrow features are interpreted to be flutes, carved in the Ross Sea floor in the past by an ice sheet much larger than today. Till can be sculpted into drumlins. These are large mounds of glacial debris that have been shaped into features that are streamlined parallel to ice flow. Often, they have a rough tear-drop shape with the tail pointing in the direction of ice flow.
Drumlins often form in groups or clusters.
Drumlins in upper New York State. These features tell us that ice sheets grew across this region in the past. There is much discussion between geologists about how drumlins form. They may form behind obstacles, just like fluted ground moraine, and may have a bedrock hill at their head. Or, big bursts of meltwater may scour away the landscape, leaving piles of material sculpted in drumlins.