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Drumlins: smooth oval hills shaped by glacial ice

All year

Drumlins are smooth, oval, elongated hills of glacial till that moving ice streamlined. Eastern Massachusetts has many of them, and the classic ones are highest at the end that faced the oncoming glacier and taper gently from there.

Why this time of year

Drumlins do not change with the seasons, so any day is a good day to spot one.

How to notice it

  1. Find a spot with a long view across a neighborhood or open land, and look for a hill that is smooth and oval rather than rocky or jagged.
  2. Trace the hill's long direction with your eyes. Drumlins are longest in the direction the ice flowed, so the long axis shows the line the glacier moved along.
  3. Compare the two ends. In a classic drumlin one end is higher and blunter and the other tapers gently, but not every drumlin follows that pattern.
  4. Look at nearby hills. Drumlins often occur together in fields, so if you find one, others of similar shape often sit close by, often lined up the same way.

Try this with kids: Draw the hill's outline like a loaf of bread or an upside-down spoon. Which end is the tall blunt end and which end is the long gentle tail?

Phrase to know: “Glacial till” means the jumbled mix of clay, sand, gravel, cobbles, and boulders a glacier leaves behind.

Safety

  • View hills from public paths, parking areas, or sidewalks, and stay off private land and steep eroding bluffs.

Sources

  • nps.govNPS: classic drumlin is highest at its up-glacier end and tapers gently, but not all taper this way; hills of sediment streamlined by glacier flow; occur together in fields; longest in the direction of flow and used to infer past glacier flow; Spectacle and Long Islands in Boston Harbor are drumlins.
  • home.nps.govNPS Boston Harbor Islands: drumlins are oblong hills of clay, sand, gravel, cobble and boulders mixed together (glacial till).
  • pubs.usgs.govUSGS abstract: Massachusetts Bay drumlins are streamlined, oval-shaped, with long axes similar to Boston Basin drumlins, indicating Laurentide ice flow direction.
  • nps.govNPS Geodiversity Atlas: glacial deposits formed whaleback mounds called drumlins; deposits are erodible.

Checked against these sources on October 20, 2026.

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