Allt Ddu, Dinorwig

Link to Welsh translationAllt Ddu, Dinorwig

Group of workmen holding lamps standing at the entrance to a tunnel at
Dinorwig Quarry around the late 19th century. © Gwynedd Archives Service

Thousands of men walked along the path here at Allt Ddu on their way to work in the Dinorwig slate quarry from the local area to the west.

The quarry was owned by the Assheton-Smith family and later another branch of the same family called Duff. Dinorwig’s rival was the Penrhyn quarry near Bethesda. By 1882, 92% of Britain’s slate production came from Wales. Between them, Dinorwig and Penrhyn produced half of that total output.

Dinorwig was part of the Faenol estate. When the quarry opened in the late 1780s, Dinorwig’s owners rented the slate beds to others. This changed in 1809 when the owner of the Faenol estate, Thomas Assheton-Smith, took control of slate quarrying on his land. Assheton-Smith developed the business and his estate made a lot of money from the Dinorwig quarry.

Dinorwig remained under the ownership of the same family until its closure and sale in 1969. The family line ended with the death of the quarry’s last owner, Michael Robert William Duff, in 1980.

Group of quarrymen working at the bottom of an incline in the mid-19th century.
Some are splitting and dressing slates. Others are riding in tramway vehicles
known as ‘velocipedes’. © Gwynedd Archives Service

In 1974 work began on the construction of a hydro-electric power station on the site of the abandoned quarry. To preserve the beauty of the site the power station was built into the mountain. The power station opened in 1984 and is still in operation today.

Some of the quarrymen came from the local area around Dinorwig. Many others travelled great distances to work at the quarry. Those who travelled from other parts of Wales often stayed on site during the week and travelled home to see their families at the weekend. Some travelled from Llangefni, Llanerchymeddd, Brynsiencyn, Niwbwrch, Gaerwen, Llangaffo, Dwyran, Pentre Berw, Llanddaniel and Bodorgan on Anglesey. They also came from other parts of North Wales, such as Waunfawr, Eifionydd, Caernarfon and the Llŷn Peninsula.

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