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Portmadoc Harbour

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NPRN306317
Map ReferenceSH53NE
Grid ReferenceSH5701438378
Unitary (Local) AuthorityGwynedd
Old CountyCaernarfonshire
CommunityPorthmadog
Type Of SiteHARBOUR
PeriodPost Medieval
Description

1.

Porthmadog Harbour was constructed by W. A. Madocks between 1821 and 1825. It came into existence fortuitously as a result of Madocks' reclamation works on Traeth Mawr between 1808 and 1811. The building of the cob and the installation of a tidal gate caused the river Glaslyn to scour out a deep-water channel between the rocky Ynys Tywyn and Canol y Clwt, the sloping beach to the west. Previously, local trade had centred on the natural cove of Borth y Gest, 1 kilometre to the south-west, slate for export transferred at Ynys Cyngar. A public quay was built in 1824-6, creating a busy and congested harbour. Further development followed the arrival of the Ffestiniog Railway in 1836 which required larger stackyards and quays, built by the Tramadog Estate and leased to the quarries.

Porthmadog became a centre for the international export of slate and also an important centre for shipbuilding.

Source:

  • D.Gwyn, Welsh Slate: the Archaeology and History of an Industry (RCAHMW 2015), p.227-8.

RCAHMW, 19 June 2015

2.

The main export point for slates from the Ffestiniog quarries from the 1820s to the 1940s, when the slate cargo was loaded onto a ship. Porthmadog is an industrial-era harbour, having only nvome into existence as a fortuitous consequence of the re-channelling of the Glaslyn river during the construction of the ‘cob’, the long sea-defence work across the mouth of the Traeth Bach, built between 1808 and 1811, where the waters scoured a harbour capable of taking shallow draught sailing vessels.  

Initially slate was transferred here from Dwyryd river-boats to sea-going ships, but with the construction of the railway in 1836, the river trade declined, ceasing altogether during the boom years of the 1860s. The export trade remained buoyant after the arrival of the main-line railway system connecting with the Festiniog railway ion the 1860s, and additional quays were constructed as late as 1868; however, after 1914 and the end of slate exports to Hamburg, the harbour saw little use.  

The wharves were laid out in such a way as to provide a stacking area for slates in between a criss-cross arrangement of railways and wagon-turntables. They are mainly built out of local flagstone on rock. Each one was leased to a separate quarry company.  

The Ballast Bank is an important geological location, being made up of stones and rocks brought in as ballast from all over the world. 

Porthmadog harbour is now used by yachts. The former slate warehouse is now the maritime museum and the former seamen’s mission is the yacht club. Nos 1-6 Cornhill include impressive warehouse buildings. 

Statement of Significance:

Porthmadog harbour was the main export point for slates from the Ffestiniog quarries from the 1820s, when the first quays were built, to the 1940s, when the final ship arrived to take a cargo. From 1836 to 1946 it was served by the Festiniog Railway (NPRN 34660).  It owes its origins to the re-channelling of the Glaslyn river during the construction of the ‘cob’, the long sea-defence work across the mouth of the Traeth Bach, built between 1808 and 1811, where the waters scoured a harbour capable of taking shallow draught sailing vessels. The wharves are mainly built out of local flagstone on rock. Each one was leased to a separate quarry company. Porthmadog’s evident functional linkage to the railway illustrates its role within a complete industrial-cultural landscape from the source of the slate to its onward sea-journey.    

This site is part of the Slate Landscape of Northwest Wales World Heritage Site, Component Part 5: Ffestiniog: its slate mines and quarries, slate town and railway to Porthmadog. Inscribed July 2020. 

Sources: 

•             Louise Barker & Dr David Gwyn, March 2018. Slate Landscapes of North-West Wales World Heritage Bid Statements of Significance. (Unpublished Report: Project 401b for Gwynedd Archaeological Trust) 

•             Tirwedd Llechi Gogledd Orllewin Cymru / The Slate Landscape of Northwest Wales. Nomination as a World heritage Site (Nomination Document, January 2020) 

•             Wales Slate World Heritage Site https://www.llechi.cymru/

Hannah Genders Boyd, RCAHMW, February 2022 

Resources
DownloadTypeSourceDescription
application/postscriptWSP - Welsh Slate Publication CollectionFigure 217. Map showing development of Porthmadog harbour Based upon ? Crown copyright and database rights 2014. Ordnance Survey licence no. 100022206
application/postscriptWSP - Welsh Slate Publication CollectionFfigur 217. Map yn dangos datblygiad harbwr Porthmadog. Yn seiliedig ar (h) hawlfraint a hawl cronfa ddata'r Goron 2014. Rhif trwydded yr Arolwg Ordnans 100022206