Editing North Sea (section)

== Geology ==

The North Sea occupies a large sedimentary basin formed by repeated crustal stretching and subsidence. Sandstone, shale, chalk, salt, and younger marine sediments accumulated over long periods. Several buried sandstone and chalk formations later became reservoirs for oil and natural gas.

Glaciation repeatedly altered the basin during the [[Quaternary]]. Ice sheets cut channels into the seabed and deposited clay, sand, gravel, and glacial debris. Sea level fell during the coldest periods, exposing much of the southern North Sea as a low plain known as [[Doggerland]]. It connected Great Britain with mainland Europe and contained river valleys, wetlands, and inhabited land.

The melting of the ice sheets caused sea level to rise after the last glacial period. Water entered the lower parts of Doggerland and gradually divided Britain from the continent. The present seabed preserves former river channels and glacial landforms beneath later marine deposits. Sand dominates many shallow areas, while mud is more common in deeper water. Gravel and exposed rock occur around parts of the northern and western margins.