The English Channel

The length of the Channel is most often defined as the line between Land's End and Ushant at the (arbitrarily defined) western end, and the Strait of Dover at the eastern end. The strait is also the Channel's narrowest point, while its widest point lies between Lyme Bay and the Gulf of Saint Malo near the midpoint of the waterway.[1] It is relatively shallow, with an average depth of about 120 m (390 ft) at its widest part, reducing to a depth of about 45 m (150 ft) between Dover and Calais. From there eastwards the adjoining North Sea continues to shallow to about 26 m (85 ft) in the Broad Fourteens where it lies over the watershed of the former land bridge between East Anglia and the Low Countries. It reaches a maximum depth of 180 m (590 ft) in the submerged valley of Hurds Deep, 30 mi (48 km) west-northwest of Guernsey.[3] The eastern region along the French coast between Cherbourg and the mouth of the Seine river at Le Havre is frequently referred to as the Bay of the Seine (French: Baie de Seine)[4].

Several major islands are situated in the Channel, the most notable being the Isle of Wight off the English coast and the British crown dependencies the Channel Islands off the coast of France. The Isles of Scilly off the far southwest coast of England are not generally counted as being in the Channel. The coastline, particularly on the French shore, is deeply indented. The Cotentin Peninsula in France juts out into the Channel, and the Isle of Wight creates a small parallel channel known as the Solent.

The Channel is of geologically recent origins, having been dry land for most of the Pleistocene period. It is thought to have been created between 450,000 and 180,000 years ago by two catastrophic glacial lake outburst floods caused by the breaching of the Weald-Artois Anticline, a ridge which held back a large proglacial lake in the Doggerland region, now submerged under the North Sea. The flood would have lasted several months, releasing as much as one million cubic metres of water per second. The cause of the breach is not known but may have been caused by an earthquake or simply the build-up of water pressure in the lake. As well as destroying the isthmus that connected Britain to continental Europe, the flood carved a large bedrock-floored valley down the length of the English Channel, leaving behind streamlined islands and longitudinal erosional grooves characteristic of catastrophic megaflood events.[5]

The Celtic Sea forms its western border.