This lowland area gains its character and general appearance from the drape of egg-shaped hills called drumlins. They were formed in the final stages of the glaciation when the thin and rapidly melting ice flowed over a bed of glacial debris, sculpting the mounds as it passed. These hills, each up to 800m long and 500m in width, have hummocks and depressions on their flanks and are separated by hummocky, pock-marked ground. The long axes of the drumlins betray the direction of ice flow. The drumlins themselves are composed of a mix of sands, gravels and clays (a diamict) and their slopes are often composed of beds of gravel and pebbles grading upwards into the diamict. It seems likely that these deposits formed in meltwater channels gushing around the drumlin mounds beneath the ice cover.
The well-defined depressions between them, anything up to 2.5 hectares in extent, are the cavities left by the late melting of masses of static ice stranded and largely buried by glacial debris. Such steep-walled depressions (called kettle holes) are often filled with water, creating ponds and miniature lakes.
