It's hard to imagine today but the reserve was once covered in ice over a kilometre thick, more than the length of ten football pitches! Anyone who has been to or seen images of Antarctica or the Himalayas will appreciate what this amount of ice looks like.
The effects of repeated ice sheet advances and retreats have created the landforms we see around us today (The valleys of the Lake District being the best example). The last ice sheet retreat at Watchtree some eighteen thousand years ago left an undulating landscape consisting of low oblong shaped hills called drumlins. Drumlins consist of glacial deposits or boulder clay (till). It is this superficial layer of boulder clay that covers the bedrock a few metres below.
The most recent geological research suggests that the higher ground on which Watchtree sits has been shaped by huge ice sheets literally moving the earth to leave an elongated landscape.