Hunts Bay Oolite is an oolitic Carboniferous

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

found in the south

Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...

region. It is named after Hunts Bay on the

Gower Gower ( cy, Gŵyr) or the Gower Peninsula () in southwest Wales, projects towards the Bristol Channel. It is the most westerly part of the historic county of Glamorgan. In 1956, the majority of Gower became the first area in the United Kingdom ...

peninsula, south-south west of Bishopston, where a significant amount of the limestone forms the cliffs there. Bracelet Bay - geograph

Hunts Bay Oolite is a sub-group of the

Pembroke Limestone Group The Pembroke Limestone Group is a stratigraphic unit of Courceyan to Brigantian age (Early Carboniferous) found in southern Wales and northern Somerset. It forms part of the Carboniferous Limestone Supergroup. These carbonate rocks developed i ...

which itself is part of the

Carboniferous Limestone Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian epoch (geology), Epoch of the Carboniferous period (geology), Period. T ...

Supergroup. Oolite means 'egg stone': very small grains (up to 2mm) form by accumulating precipitated minerals, usually calcium carbonate. These ooids, created in a warm, tropical environment, are the precursors to the limestone. The Hunts Bay Oolite extends from Pembroke in the West to Monmouth and

Chepstow Chepstow ( cy, Cas-gwent) is a town and community in Monmouthshire, Wales, adjoining the border with Gloucestershire, England. It is located on the tidal River Wye, about above its confluence with the River Severn, and adjoining the wester ...

in the East and northwards into the Dowlais Limestone Formation around Merthyr Tydfil. Fossils, such as

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...

s and

crinoid Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are ...

s associated with a shallow sea environment, can be found in the rock. East of the

South Wales Coalfield The South Wales Coalfield ( cy, Maes glo De Cymru) extends across Pembrokeshire, Carmarthenshire, Swansea, Neath Port Talbot, Bridgend, Rhondda Cynon Taf, Merthyr Tydfil, Caerphilly, Blaenau Gwent and Torfaen. It is rich in coal deposits, espe ...

and in the south east the rock is increasingly dolomitised (where some

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

is replaced by

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

). This subgroup was deposited in equatorial seas largely during the Holkerian (British regional) substage of the

Viséan The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from to Ma. It follow ...

stage of the Carboniferous, from 337 to 333.5 million years ago.

References

* {{cite web, title= Fossilworks: Gateway to the Paleobiology Database, author= ((Various Contributors to the Paleobiology Database)), url= http://www.fossilworks.org/cgi-bin/bridge.pl?action=home, access-date= 8 July 2014 Carboniferous System of Europe Carboniferous Wales

See also

References