What is a Drumlin? - Definition & Formation

Instructor: Suzanne Rebert

Suzanne has taught college economics, geography, and statistics, and has master's degrees in agricultural economics and marine affairs (marine resource management).

In this lesson you will learn about drumlins, one of the major features of glacial landscapes. You'll also take a quiz to check your understanding of the subject.


If you have a dog, you've probably used your detective skills to figure out what your pet has been up to all day while you've been at work or school. A trail of toys (or shredded paper, or even your shoes and socks) can give you clues about where your dog played, ate, and napped, as well as where she got tired of carrying a particular item and decided to leave it behind. You can play detective with geology, too. In some ways, even a powerful geological force such as a glacier is a little like an enormous puppy, and the landforms ancient glaciers left behind can tell us what they were up to all those thousands of years ago.

Drumlin on Waterville Plateau, Washington state
drumlin on Waterville Plateau, Washington state

A drumlin is a kind of glacial deposit. 'Drumlin' comes from the Gaelic word droimnín, meaning 'smallest ridge.' Drumlins are made up of glacial till, sand and gravel that were being transported by a moving glacier and left behind. These hilly features when viewed from above (plan view) are shaped like teardrops or elongated eggs. The side view (profile or cross section) reveals that the large, rounded end of a drumlin has the steepest slope and the highest elevation, while the long end slopes gently, like a ramp. These are not huge mountains; they range from 100 meters to 1 kilometer long, are about half as wide, and are 10 or so meters high. But they definitely live by the concept of 'strength in numbers': hundreds and hundreds of drumlins usually occur together as a swarm scattered over a wide area.


Drumlin cross section and plan views
drumlin diagram, cross section and plan views

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