Dee estuary
| Site of Special Scientific Interest | |
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 Location within Flintshire
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| Area of Search | Merseyside & Cheshire, England & Flintshire, Wales |
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| Grid reference | SJ200800 |
| Coordinates | 53°18′32″N 3°09′25″W / 53.309°N 3.157°WCoordinates: 53°18′32″N 3°09′25″W / 53.309°N 3.157°W |
| Interest | Geological |
| Area | 13679.7 hectares, 33,788.9 acres (136,739,000 m2) |
| Notification | 1954 /1984 |
| Natural England website | |
The Dee Estuary (Welsh: Aber Dyfrdwy) is a large estuary by means of which the River Dee flows into Liverpool Bay. The estuary starts near Shotton after a five-mile (8 km) 'canalised' section and the river soon swells to be several miles wide forming the boundary between the Wirral Peninsula in north-west England and Flintshire in north-east Wales.
The estuary is unusual in that comparatively little water occupies so large a basin. One theory is that larger rivers such as the Severn and/or Mersey once flowed into the Dee. The current view is that the estuary owes its origin to the passage of glacial ice southeastwards from the Irish Sea during successive ice ages, eroding a broad and shallow iceway through the relatively soft Triassic sandstones and Coal Measures mudstones underlying the area. The inner parts of this channel were filled by glacially derived sands and gravels long ago, and infilling by mud and silt has continued since. It is also thought that prior to the ice ages, the estuary received larger river flows as the upper Severn flowed into the Dee near Chirk. For a period, the Mersey may also have flowed into the Dee by means of a channel which it cut through the base of the Wirral Peninsula.
The estuary is a major wildlife area and one of the most important estuaries in Britain, amongst the most important in Europe for its populations of waders and wildfowl. The Environment Agency is the Conservation Authority, and the estuary is protected or listed under several schemes:
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Wikipedia