The North Sea is a large, shallow epicontinental sea dominated by a sandy bottom that reflects a high-energy environment. Little is known about the environmental history of the Danish part of this large area during the Weichselian, the last ice age. Parts of it were glaciated during the last glacial maximum and probably also during older glaciations. Shallow parts were dry land, and deeper parts were covered by the sea during ice-free intervals. Large, partly ice-dammed lakes also existed.
René Taudal Poulsen, An environmental history of North Sea ling and cod fisheries, 1840-1914