View north-westwards from Carnllundain - geograph

The Bishops and Clerks are a group of rocks and islets, approximately west of Ramsey Island,

Pembrokeshire Pembrokeshire ( ; cy, Sir Benfro ) is a Local government in Wales#Principal areas, county in the South West Wales, south-west of Wales. It is bordered by Carmarthenshire to the east, Ceredigion to the northeast, and the rest by sea. The count ...

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

Origins of the name

There was a local tradition that the name arose from the sixteenth century wreck of a fleet of merchant ships from which there were only three survivors: Miles Bishop, James Clerk and Henry Clerk. However, this derivation is now thought to be unlikely and that the name probably comes from there being a larger island surrounded by smaller islands. Similar names are used for islands in the

Isles of Scilly The Isles of Scilly (; kw, Syllan, ', or ) is an archipelago off the southwestern tip of Cornwall, England. One of the islands, St Agnes, is the most southerly point in Britain, being over further south than the most southerly point of the ...

and for the

Bishop and Clerk Islets The Bishop and Clerk Islets are a group of islets, lying south of Macquarie Island in the southwestern Pacific Ocean. They are, with Macquarie Island, part of the Australian state of Tasmania. The group consists of Bishop Islet, 24 smaller ...

in the southwestern Pacific Ocean. The islands are named as in the manuscript ''Sailing Directions for the Circumnavigation of England'' which dates from the middle fifteenth century or earlier. They are named ''The bisshop and his clarkes'' in a 1578 map of Pembrokeshire by Christopher Saxton. An ecclesiastical link is supported by the Pembrokeshire antiquarian George Owen:

Geography

There are four distinct groups of islets. From the north these are: *North Bishop (44 metres, 144 feet) *Carreg Rhoson (44 metres, 144 feet) *Carreg Rhoson E Island (30 metres, 98 feet) **Maen Rhoson *Daufraich **Maen Daufraich **Moelyn **Cribog *

Emsger Emsger or South Bishop is an islet situated west of Ramsey Island, Pembrokeshire, Wales. It is the largest of the Bishops and Clerks group of islets and rocks. Etymology Its name can also be shown as Em-sger, Emskir or Emskyr. The second elemen ...

or South Bishop (37 metres, 121 feet) In addition, the three small wave-washed rocks of Carreg-trai, Llechau-isaf and Llechau-uchaf sit in the waters between the Bishops and Clerks and Ramsey Island and the Welsh mainland.

Lighthouse

The islands and their neighbouring rocks are dangerous to shipping, and about thirteen shipwrecks are recorded in the waters immediately surrounding the islands, notably North Bishop. The South Bishop Lighthouse was built on Emsger (South Bishop) in 1939.

Geology

The two northerly islet groups are formed from

gabbro Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is che ...

, a hard-wearing rock of

igneous Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...

origin whilst those of the Daufraich group to their south (and indeed Llechau-isaf) are formed from microtonalite, another intrusive igneous rock. The most southerly, Emsger is formed from

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

. All these are of probable lower

Palaeozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and '' ...

origin. Llechau-uchaf is formed from the late

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

'Lingula Flags' whilst Carreg-trai is formed from Ordovician acid

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...

s of the Llanrian Volcanic Formation.British Geological Survey 1992 1:50,000 scale provisional geological map sheet 209 (England and Wales) ''St David's'' The submarine geology between the main groups is formed by

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

s and

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

s of Cambro-Ordovician age, though the bedrock is partly covered by sand and gravel.

References

External links

Photograph
{{coord, 51.87, -5.395, display=title Islands of Pembrokeshire