The high ground on each bank of the Humber Esstuary consists of the Yorkshire and Lincolnshire Wolds of cretaceous chalk and, to the west, the low limestone escarpment leading to Brough-on-Humber on the north and the Lincoln Edge southwards, separated from the Wolds by the Ancholme River vally; the Edge is a much more prominent feature than its northern counterpart. To east and west of this high ground low-lying, and in olden days marshy, terrain surrounds the estuary and the rivers which drain into it.

During the last Ice Age what is now the Humber Estuary formed part of 'Lake Humber' which was dammed by glacial moraine to the east and drained to the south along the Ancholme Valley. Later, the river cut a channel eastwards to the sea and the River Ancholme reversed its course and the present drainage system was formed.

After glacial retreat at the end of the last Ice Age a surface of barre