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The Solent ( ) is the strait that separates the Isle of Wight from the mainland of England. It is about 20 miles in length and varies in width between one and four miles. The Solent is a major shipping route for passenger, freight and military vessels. It is an important recreational area for water sports, particularly yachting,〔(Solentpedia: recreation )〕 hosting the Cowes Week sailing event annually. It is sheltered by the Isle of Wight and has a very complex tidal pattern, which has greatly benefited Southampton's success as a port, providing a "double high tide" that extends the tidal window during which deep-draught ships can be handled.〔(DP World Container Port information )〕 Portsmouth lies on its shores. Spithead, an area off Gilkicker Point near Gosport, is known as the place where the Royal Navy is traditionally reviewed by the monarch of the day. The area is of great ecological and landscape importance, particularly because of the coastal and estuarine habitats along the edge of the Solent.〔(Solentpedia: biodiversity )〕 Much of its coastline is designated as a Special Area of Conservation.〔(Solentpedia: protected areas )〕 It is bordered by and forms a part of the character of a number of nationally important protected landscapes including the New Forest National Park, and the Isle of Wight AONB. First recorded in 731 as ''Soluente'', Solent is "an ancient pre-English name of uncertain origin and meaning".〔A.D. Mills, ''Oxford Dictionary of English Place-Names'', 2nd ed. (Oxford University Press, 1998: ISBN 0-19-280074-4), p. 318.〕 ==Geology== Originally a river valley, the Solent has gradually widened and deepened over many thousands of years. The River Frome was the source of the River Solent, with three other rivers — the Rivers Avon, Itchen and Test — being tributaries of it. Seismic sounding has shown that when the sea level was lower the River Solent incised its bed to a depth of at least below current Ordnance Datum.〔(The buried channels of the ‘Solent River’, southern England )〕 The Purbeck Ball Clay contains kaolinite and mica, showing that in the Lutetian stage of the Eocene water from a granite area, probably Dartmoor, flowed into the River Solent. Seabed survey shows that when the sea level was lower in the Ice Age the River Solent continued the line of the eastern Solent (Spithead) to a point roughly due east of the east end of the Isle of Wight and due south of a point about west of Selsey Bill, and then south-south-west for about , and then south for about , and then joined the main river flowing down the dry bed of the English Channel. Since the retreat of the most recent glaciation the South East of England, like the Netherlands, has been steadily slowly sinking through historic time due to forebulge sinking. A new theory – that the Solent was originally a lagoon – was reported in the ''Southern Daily Echo'' by Garry Momber from the Hampshire and Wight Trust for Maritime Archaeology.〔(thisishampshire.net, ''Startling evidence of a Stone Age structure in the Solent.'' ) - Retrieved 03 Oct. 2009〕〔(SCOPAC Research Project - Archaeology & Coastal Change )〕 The Isle of Wight was formerly contiguous with the Isle of Purbeck in Dorset — the Needles are the last remnant of this connection. Ten thousand years ago a band of relatively resistant Chalk rock, part of the Southern England Chalk Formation, ran from the Isle of Purbeck area of south Dorset to the eastern end of Isle of Wight, parallel to the South Downs. Inland behind the Chalk were less resistant sands, clays and gravels. Through these weak soils and rocks ran many rivers, from the Dorset Frome in the west and including the Stour, Beaulieu River, Test, Itchen and Hamble, which created a large estuary flowing west to east and into the English Channel at the eastern end of the present Solent. This great estuary ran through a wooded valley and is now referred to as the Solent River.〔 When glaciers covering the north of Britain melted at the end of the last ice age, two things happened to create the Solent. Firstly, a great amount of flood water ran into the Solent River and its tributaries, carving the estuary deeper. Secondly, post-glacial rebound after the removal of the weight of ice over Scotland caused the island of Great Britain to tilt about an east-west axis, because isostatic rebound in Scotland and Scandinavia is pulling mantle rock out from under the Netherlands and south England: this is forebulge sinking. Over thousands of years, the land sank in the south (a process still continuing) to submerge many valleys creating today's characteristic rias, such as Southampton Water and Poole Harbour, as well as submerging the Solent. The estuary of the Solent River was gradually flooded, and eventually the Isle of Wight became separated from the mainland as the chalk ridge between The Needles on the island and Old Harry Rocks on the mainland was eroded. This is thought to have happened about 7,500 years ago. The process of coastal change is still continuing, with the soft cliffs on some parts of the Solent, such as Fort Victoria, constantly eroding, whilst other parts, such as Ryde Sands, are accreting. The Solent is a comparatively shallow stretch of tidal water. It has an unusual double tide〔(Bristol Nomads website )〕 that is both favourable and hazardous to maritime activities with its strong tidal movements and quickly changing sea states. Coupled with the above, the Solent is renowned for its large volume of vessel usage, thus resulting in one of the highest density of declared lifeboat stations in the world. This includes six RNLI (e.g. Calshot and Cowes) and five independently run stations (e.g. Hamble Lifeboat and Gosport and Fareham Inshore Rescue Service). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Solent」の詳細全文を読む スポンサード リンク
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