Penmon Quarry

Overview

A limestone quarry at the north-eastern tip of Anglesey, one of a group along the island’s north-east coast — with Traeth Bychan, Benllech, Castle Rock at Red Wharf Bay, Llandona and Flagstaff — that produced block for the two great crossings of the Menai Strait. Telford’s Menai Suspension Bridge of 1819–26 took the stone for its arches and piers from Penmon, carried down by boat; Stephenson’s Britannia Bridge, whose foundation stone was laid in 1846, used Penmon limestone for its stonework too. The same stone had gone into Beaumaris and Caernarfon castles and later into the Manchester Ship Canal.

History

Penmon is one of several limestone quarries along the north-east coast of Anglesey — the others being Traeth Bychan, Benllech, Castle Rock at Red Wharf Bay, Llandona and Flagstaff — and all of them produced block for the two bridges over the Menai Strait. Anglesey limestone has been quarried and worked by masons on the island since the eighteenth century. Construction of Telford’s Menai Suspension Bridge began in 1819 against much opposition from the ferry owners and the tradesmen of the ports. The stone for its arches and piers was limestone quarried at Penmon at the north end of the strait, then carried down to the site by boat; the ironwork came from Hazeldine’s foundry near Shrewsbury and was immersed in warm linseed oil to keep it from rusting before it was used. A generation later Stephenson’s Britannia Bridge, whose foundation stone was laid on 10 April 1846, was built of the same stone: like the Menai Bridge, its stonework was constructed of limestone from Penmon, with sandstone from various places used internally. Penmon stone had older and later uses too — Beaumaris and Caernarfon castles, and the Manchester Ship Canal.

Geology

Carboniferous Limestone, which occupies a broad area of Anglesey south of Lligwy Bay and Pentraeth and sends a narrow spur south-westward by Llangefni to the Malltraeth sands; it appears again on the south coast about Llanfihangel and Llangoed, and in the south-west round Llanidan on the Menai Strait. Puffin Island, off Penmon, is made of it. The limestone is underlain to the north-west by a red basement conglomerate and yellow sandstone. It is a hard limestone that takes a high polish and weathers well — the qualities that made it worth shipping for engineering work rather than merely burning for lime.

Workings

Open quarries worked into the coastal limestone, with the stone shipped out by sea: the Menai Bridge stone was carried down the strait by boat from the quarry, and Port Penmon served the workings. Penmon was one of a group of north-east coast quarries operating together, and Aber Quarry is the only one of them still in production.

Closure

No closure date has been established for Penmon itself. Of the group of north-east Anglesey quarries that supplied the Menai bridges, only Aber Quarry remains in production.

What remains

The workings and Port Penmon are ruinous; the quarry ground at the tip of the island is open and much visited, with Puffin Island offshore. Anglesey limestone is still quarried on the island at Aber Quarry, the last of the group at work.

Quarry faces and the remains of the harbour at Port Penmon.

Nearby mines

• Penrhyn Quarry — 13.3 km S, Gwynedd
• Pantdreiniog Quarry — 13.9 km S, Gwynedd
• Great Orme Copper Mines — 14.0 km E, Conwy
• Cwm Eigiau Quarry — 14.5 km SE, Gwynedd

Straight-line distance, within 15 km. Show on the map.

Recorded claims

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

• The stone used for the arches and piers of Telford’s Menai Suspension Bridge, begun in 1819, was limestone quarried from Penmon at the north end of the strait and carried down by boat. ¹
• Like the Menai Bridge, the stonework of Stephenson’s Britannia Bridge was constructed of limestone from Penmon, with sandstone from various places used internally; its foundation stone was laid on 10 April 1846. ¹
• There were several quarries along the north-east coast of Anglesey — Traeth Bychan, Benllech, Castle Rock at Red Wharf Bay, Llandona, Penmon and Flagstaff — and all of them produced block for the two bridges over the Menai Straits; Aber Quarry is now the only one still in production. ²
• The limestone is Carboniferous, occupying a broad area south of Lligwy Bay and Pentraeth with a narrow spur south-westward by Llangefni to the Malltraeth sands, and underlain to the north-west by a red basement conglomerate and yellow sandstone; it is hard enough to take a high polish and has excellent weathering properties. ²

Photographs & further reading

Sources

1. (secondary) Menai Strait bridges — Anglesey History
2. (secondary) About Anglesey Masonry: Anglesey limestone — Anglesey Masonry

Record created: 7 September 2026 · Last researched: 7 September 2026