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The Bristol Channel ((ウェールズ語:Môr Hafren), meaning 'Severn Sea') is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset in South West England. It extends from the lower estuary of the River Severn ((ウェールズ語:Afon Hafren)) to the North Atlantic Ocean. It takes its name from the English city of Bristol, and is over 30 miles (50 km) across at its widest point. Long stretches of the coastline of the Bristol Channel, on both the South Wales and West Country sides, are designated as Heritage Coast, including Exmoor, Bideford Bay, the Hartland Point peninsula, Lundy Island, Glamorgan, Gower Peninsula, South Pembrokeshire and Caldey Island. ==Geography== The International Hydrographic Organisation defines the western limit of the Bristol Channel as "a line joining Hartland Point in Devon () to St. Govan's Head in Pembrokeshire ()". The upper limit of the Channel is between Sand Point, Somerset (immediately north of Weston-super-Mare) and Lavernock Point (immediately south of Penarth in South Wales). East of this line is the Severn Estuary. Western and northern Pembrokeshire, and north Cornwall are outside the defined limits of the Bristol Channel, and are considered part of the seaboard of the Atlantic Ocean, more specifically the Celtic Sea. Within its officially defined limits, the Bristol Channel extends for some from west to east, but taken as a single entity the Bristol Channel - Severn Estuary system extends eastward to the limit of tidal influence near Gloucester. The channel shoreline alternates between resistant and erosional cliff features, interspersed with depositional beaches backed by coastal sand dunes; in the Severn Estuary, a low-lying shoreline is fronted by extensive intertidal mudflats.〔Steers, J.A., 1964. The Coastline of England and Wales. Cambridge Univ. Press, Cambridge, 750 pp.〕 The Severn Estuary and most of the embayments around the channel are less than 10 m in depth. Within the channel, however, there is an E-W trending valley 20 to 30 m in depth that is considered to have been formed by fluvial run-off during Pleistocene phases of lower sea level.〔Collins, M.B., 1987. Sediment transport in the Bristol Channel: a review. Proceedings of the Geological Association 98, 367-383.〕 Along the margins of the Bristol Channel are extensive linear tidal sandbanks that are actively mined as a source of aggregates and in the Outer Bristol Channel off the Welsh coast are the OBel Sands, an extensive area of sand waves up to 19 m high, covering an area of over 1,000 km2.〔James, J.W.C., Mackie, A.S.Y., Rees, E.I.S., Darbyshire, T., 2012. Ch. 12: Sand wave field: The OBel Sands, Bristol Channel, U.K. , in: Harris, P.T., Baker, E.K. (Eds.), Seafloor geomorphology as benthic habitat: GeoHAB Atlas of seafloor geomorphic features and benthic habitats. Elsevier, Amsterdam, pp. 227-240.〕 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「Bristol Channel」の詳細全文を読む スポンサード リンク
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