Timeline: Some Important Dates

500 million years ago: the creation of slate

1300s Cilgwyn Quarry, Nantlle, is in production


1787 Dinorwig Quarry is established

1790 Port Penrhyn is developed for export business


1801 Penrhyn Tramway opens

1818 Welsh Slate Company’s quarry opens in Blaenau Ffestiniog

1820 Construction of Porthmadog harbour

1830 Penybryn Quarry, Nantlle, is the first user of chain inclines

1848 steam locomotives are first used on the Padarn Railway

1874 North Wales Quarrymen’s Union is established

1874 steam locomotives are introduced at Port Penrhyn

1881 Ffestiniog parish has over 11,000 inhabitants

1890 hydro-electricity is first used at Llechwedd Quarry


1900–3 The Penrhyn strike, one of the longest in British labour history

1918 Minimum wage is agreed by quarry owners and union officials

1920s Crushing mills are erected at Penrhyn Quarry, to grind slate waste used in road construction

1940s Slate waste is used to make building blocks

1964 The Alfred McAlpine company purchase Penrhyn Quarry

1969 Closure of Dinorwic Quarry, establishment of museum

1972 Llechwedd Slate Caverns open to the public

1999 A large shipment of slates from Penrhyn Quarry is sent to Australia, for storm repairs

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