Drumlins are long, low hills made of glacial till which were deposited beneath glaciers during the last ice age (before about 20 000 years ago). they are elongated features which may be approx 1km long, 500m wide and 50m high. Despite the ingrained belief that they are asymmetric in profile with a steeper stoss (upflow) and gentle, tapered lee (downflow) slope, recent research shows they are actually largely symmetrical in profile.