History

Complete dock system with entrance lock, long dock crossed by bascule bridge and graving-dock at upper end, converted from a tidal inlet of Afon Heulyn, previously partially used as a quay. It was designed and supervised by Frank Oswell BA (Associate Member, Institution of Civil Engineers), at a cost of £18,527. Lock-gates and cast-iron bollards by Cleghorn & Wilkinson, Northwich; the bridge was constructed by Pearson & Knowles, based in Warrington. Work began in April 1897 and was completed in December 1900.

Port Dinorwic was successively developed and enlarged from the 1790s by the Assheton-Smith family of Vaynol, owners of the Dinorwic slate quarry, Llanberis. Their quarries produced by late 1890s almost one quarter of the entire output of Welsh slate. The outer end of the system probably incorporates stonework from the quays of the 1820s.

Exterior

Dock system approx 500m long, following line of former natural inlet. At outer (W) end of system is entrance lock in dressed grey stone; 2 lock gates in wood with walkways over having railings consisting of iron posts and chains. Inner dock walls in red brick with massive stone capstones and dressings (some capstones replaced in concrete); ladders set into dock sides. Dock broadens inside lock before narrowing at single-leaf bascule bridge. Steel bridge pivots at S end (modified with an electric drive motor in 1912); sloping parapets become (at S end) semi-circular with teeth which engage with raising mechanism. E of bridge, the dock curves and varies in width, following line of the natural inlet. At inner end of system is dry dock, or graving-dock, sealed by steel caisson. Dry-dock has stepped side-walls and polygonal E end.

Reasons for Listing

A remarkable example of a complete dock-system built to service a Welsh industry of world importance.

External Links

• Cadwr Listing
• Wikidata Q29494967

External links are from the relevant listing authority and, where applicable, Wikidata. Wikidata IDs may be related buildings as well as this specific building. If you want to add or update a link, you will need to do so by editing the Wikidata entry.

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