Coastline of the North Sea

The coastlines along the southernmost part are soft, covered with the remains of deposited glacial sediment, which was left directly by the ice or has been redeposited by the sea.

[1] The Norwegian mountains plunge into the sea, giving rise, north of Stavanger, to deep fjords and archipelagos.

Starting from Flamborough Head in the north east of England, the cliffs become lower and are composed of less resistant moraine, which erodes more easily, so that the coasts have more rounded contours.

[4][5][6] The northern North Sea coasts bear the impression of the enormous glaciers which covered them during the Ice Ages and created fjords, lakes and valleys along the coastline and landscape.

[2][3] The cliff landscape is interrupted in southern England by large estuaries with their corresponding fringing marshes, notably the Humber and the Thames.

The coastal brim (Strandflaten), which is found especially in southern Norway, is a gently sloping lowland area between the sea and the mountains.

[23] The small, historically strategic island of Heligoland was not formed by recent sediment deposition; it is considerably older and is composed of early Triassic sandstone.