Drumlin

Drumlin

A drumlin is an elongated whale-shaped hill formed by glacial action. Its long axis is parallel with the movement of the ice, with the blunter end facing into the glacial movement. Drumlins may be more than 150 ft (45 m) high and more than 1/2 mi (.8 km) long, and are often in drumlin fields of similarly shaped, sized and oriented hills. Drumlins usually have layers indicating that the material was repeatedly added to a core, which may be of rock or glacial till.

There are many theories as to the exact mode of origin. Some consider them a direct formation of the ice, while others think they are created by highly pressurized water flow underneath the glacier. Either way, they are thought to be a waveform (similar to ripples of sand at the bottom of a stream). It is also poorly understood why drumlins form in some gaciated areas and not in others.

Drumlins are common in New York, the lower Connecticut River valley, Wisconsin, Canada, Poland and Northern Ireland. They are regarded as a creation of the last Wisconsonian Ice age.

See also