Quarrying Slate

Dinorwig Quarry was carved out of the mountain itself – Elidir mountain, high above Gilfach Ddu. The first step in the process of quarrying slate was to free a piece of rock – which might weigh hundreds of tons – from the face. The quarrymen would drill into the rock and fill it with powdwr du (‘black powder’) or explosive. One man would place a fuse in the powder and fire it before running to join his workmates in the blast shelter.

The blasting happened at particular times of day.


After returning to the rock face the men would need to clear the rubble and any precarious sections of rock. Two quarrymen would then turn the slate bock into 'pillars' of 100kg–200kg each with a cold chisel and a hammer. Another two members of the team would be working in one of the open sheds. Having pillared the blocks into rectangular slabs, one of the men would then split them to different thicknesses, depending on the quality of the rock. Using a wide-bladed splitting chisel and a mallet of African oak he would aim to get 16 slates from the one piece – depending on the quality.

Names of the Galleries

All the galleries in the quarries had their own names. These often had a conection with historical events such as wars and battles (e.g. Crimea and Sebastopol in the Penrhyn Quarry) — sometimes, local characters. Dinorwig Quarrymen, for example, would sometimes boast that they had visited both Abysisnia and California on the same day! There were more homely names as well, such as Alice, Aberdaron and Princess May. A number of the waggons in the Museum's collection still bear the names of the galleries where they were used.

In the meantime his partner would sit on a 'traval', a straight edge of iron and steel in a sloping piece of wood. He would trim the slate into a right angle with a guillotine knife, and then dress it to a particular size. This would all happen very quickly, almost withouth pause to draw breath, but although it might look effortless it called for a very keen eye and a sound understanding of the nature of the rock.

Crow bar

Later on electrically powered machines were used to saw and dress the slates. By using these in a damp atmosphere less damage was done to the quarrymen's lungs. But the machines could not do everything a human being could, and today slates are still split by hand in Wales.

The slates would then be weighed and carried on waggons down the incline and from there to Felinheli or Port Dinorwic as it became known to be exported – or to be stored for a while, if the slate trade was not particularly flourishing.

The Quarry

The quarry was a different world to the workshops. All the blasting work there meant that the mountain changed its shape and its geography on an almost daily basis. The galleries reared up to 650 metres above sea level, yet the quarrymen knew every part of this maze of sheds and cabins and levels and paths by name.

The Bargain

The quarries ran on the 'bargain' system. The bargain was a piece of rock about six metres square, and members of the bargain team would be trained to work on the galleries — the high terraces in the rock where the slate was actually mined — and in the sheds. A certain sum would be paid for good rock, a lower sum for rubble. The quarry steward's work then was to lower the price as far as he could by extolling the virtues of the rock; meanwhile the men would try to raise it by criticising the rock and pointing out its shortcomings. The wages of all members of the team depended on the results of this bargaining: no surprise, then, that this system was open to all sorts of manipulation.

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