Pont y Fenni Quarry

Overview

Pont y Fenni is a small disused quarry and an adjoining road cutting in Carmarthenshire, notified together as a Site of Special Scientific Interest in 1985 and covering four tenths of a hectare. It is a key faunal locality for the Arenig Series: well-preserved faunas of that age are rare in South Wales because later earth movements deformed or destroyed them, and this section escaped, yielding trilobites, graptolites, brachiopods, bivalves, hyoliths, ostracods and phyllocarids in condition good enough for detailed study.

History

Nothing on record establishes when the quarry was opened, by whom, for what, or when it stopped. Its designation covers the quarry together with the road cutting beside it, which is a fair indication of scale: a small working and the face the road engineers left, taken together as one exposure.

The site was notified as a Site of Special Scientific Interest in 1985, at grid reference SN 238169, covering 0.4 hectares.

The citation calls the exposure a key faunal locality for the hirundo Zone of the Arenig Series: rocks laid down under the sea over 500 million years ago, yielding trilobites, graptolites, brachiopods, bivalves, hyoliths, ostracods and phyllocarids preserved well enough for detailed study, a rarity in South Wales, where later folding and faulting destroyed or deformed most such fossils.

Geology

The quarry and road cutting are a key faunal locality for the Arenig Series — Early Ordovician rocks, and specifically the hirundo Zone. What makes the site matter is not that the fossils are unusual but that they survived: well-preserved faunas are rare in the hirundo Zone Arenig rocks of South Wales, including the classic ground around St David's, because of the tectonic deformation those rocks have been through. Folding and faulting after the rocks formed destroyed or distorted a great many specimens elsewhere.

Here the fauna is diverse and well enough preserved for detailed palaeontological study: trilobites, graptolites, brachiopods, bivalves, hyoliths, ostracods and phyllocarids. The assemblage dates from more than 500 million years ago, when this area lay beneath the sea.

Geological setting: Sedimentary Beds and Seams (surviving physical example)

Workings

A small quarry with an adjoining road cutting, together covering 0.4 hectares. Nothing on record describes the face, the depth or the plant, and the two exposures are treated as one site in the designation.

Closure

The closure date is not known. The quarry was disused when the site was notified in 1985 and nothing on record narrows it further.

What remains

A designated Site of Special Scientific Interest of 0.4 hectares, comprising the quarry and the road cutting beside it, valued for the section and the fauna it exposes rather than for anything left of the quarrying.

The quarry face and the adjoining road cutting, which together are the reason for the designation. Nothing on record describes a surviving quarry structure.

Related mines

• Talar Wen Quarry — Two small Carmarthenshire quarries notified as Sites of Special Scientific Interest for the Ordovician sections and faunas they expose rather than for anything they produced — Pont y Fenni for the early Arenig, Talar Wen for the later Llandeilo, and both for their trilobites.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Pont y Fenni Quarry and Road Cutting was notified as a Site of Special Scientific Interest in 1985, at national grid reference SN 238169, covering 0.4 ha. ¹
• Pont y Fenni is a key faunal locality for the Arenig Series: well preserved faunas are rare in the hirundo Zone Arenig rocks of South Wales, notably the classic St David's area, because of tectonic deformation, and this site provides a diverse fauna well enough preserved for detailed palaeontological studies. ¹
• The quarry and roadside exposures have yielded trilobites, graptolites, brachiopods, bivalves, hyoliths, ostracods and phyllocarids. ¹
• Pont y Fenni Quarry and Road Cutting is an area displaying a wide array of fossils and is a Site of Special Scientific Interest in Carmarthen and Dinefwr, Wales. ²

Photographs & further reading

Sources

1. (primary) Pont y Fenni Quarry & Road Cutting SSSI citation — Countryside Council for Wales / Natural Resources Wales
2. (secondary) Pont y Fenni Quarry and Road Cutting — Wikipedia

Record created: 4 September 2026 · Last researched: 24 September 2026