On the east bank of the River Foyle, north east of the city of Londonderry, there is a lowland area amounting to around 12km² characterised by north-east/south-west trending bedrock ridges and cobble gravel terraces. The irregular surface of the terraces has provided hollows in which two small lakes, Lough Enaghs East and West, and many other smaller water bodies have gathered.
The terraces were originally formed in the wake of a large, retreating ice front, the meltwater washing glacial debris northwards in huge volumes. Large, isolated masses of static ice were smothered by these sediments, leading to collapse cavities when they melted. They are now ‘kettle holes', filled by the smaller ponds of the area. The erosive force of the Faughan River has reduced the original broad spread of gravels to marginal terraces.