The Somme is a river in Picardy, northern France. The river is 245 km (152 mi) in length, from its source in the high ground of the former Arrouaise Forest at Fonsomme near Saint-Quentin, to the Bay of the Somme, in the English Channel. It lies in the geological syncline which also forms the Solent. This gives it a fairly constant and gentle gradient where several fluvial terraces have been identified.

The English Channel, also called simply the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France and links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busiest shipping area in the world.

It is about 350 miles (560 kilometres) long and varies in width from 150 miles (240 kilometres) at its widest to 21 miles (34 kilometres) in the Strait of Dover. It is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some 29,000 square miles (75,000 square kilometres).

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