The
Celtic Sea (; ; ; ; ) is the area of the
Atlantic Ocean off the south coast of
Ireland. It is bounded to the east by
Saint George's Channel, the
Bristol Channel and the
English Channel, as well as adjacent portions of
Wales,
Cornwall,
Devon, and
Brittany. The southern and western boundaries are based on the
continental shelf.
History
The
Celtic heritage of the bounding lands gives the sea its name,
first proposed by
E. W. L. Holt at a 1921 meeting in
Dublin of fisheries experts from England, Ireland, Scotland and France.
The northern portion of this sea had previously been considered as part of
Saint George's Channel and the southern portion as an undifferentiated part of the "
Southwest Approaches" to Great Britain. The need for a common name came to be felt because of common
marine biology,
geology and
hydrology.
It was adopted in France before being common in the English-speaking countries.
It was adopted by marine biologists and oceanographers, and later by oil exploration firms. It is named in a 1963 British atlas, but a 1972 article states "what British maps call the western approaches, and what the oil industry calls the Celtic Sea [...] certainly the residents on the western coast [of Great Britain] don't refer to it as such."
Limits
There are no land features to divide the Celtic Sea from the open Atlantic Ocean to the south and west. For these limits, Holt suggested the 200
fathom (366 m) marine
contour and
Ushant.
The definition approved by 1974 by the
Hydrographer of the
Royal Navy for use in
Admiralty Charts was "bounded roughly by lines joining Ushant,
Land's End,
Hartland Point,
Lundy Island,
St. Govan's Head and
Rosslare, thence following the Irish coast south to
Mizen Head and then along the 200-metre
isobath to approximately the latitude of Ushant."
The
International Hydrographic Organization definition, adopted by 1976,
uses
rhumb lines and extends slightly further south. It is as follows:
- * Along the Pembrokeshire coast
- * Along the Finistère coast
- From latitude 46°30’N on this line, northwestwards to
- * Along the Cork, Waterford, and Wexford coasts to Carnsore Point.
Seabed
The seabed under the Celtic Sea is called the
Celtic Shelf, part of the
continental shelf of
Europe. The northeast portion is c.90–100m deep, increasing towards Saint George's Channel. In the opposite direction, sand ridges pointing southwest have a similar height, separated by troughs c.50m deeper. These ridges were formed by tidal effects when the sea level was lower. South of 50° the topography is more irregular.
See also
