Pen Y Bryn Quarry and tips

Cadw's description

Summary description and reason for designation

Pen y Bryn Slate Quarry is located on the north slopes of the Nantlle Valley to the NE of Cloddfa’r Lôn Slate Quarry (CN302) and NE of Pen Y Bryn / Cloddfa’r Lon Water Driven Pumping System (CN418). At its peak, the quarry was a dispersed operation, making use of a number of quarry pits and at one stage tipping waste within Dorothea Quarry (CN199). Today, the quarry remains are laid out across a relatively compact site of relict buildings, a short internal tramway system and a number of massive tips.

The origins of Pen Y Bryn slate quarry began around 1770 with slate being worked at Hen Dwll. The quarry pioneered the use of chain inclines during the 1830s and used blondins throughout its operation eventually working 4 pits - including Cloddfa’r Lon, Twll Mawr and Twll Balast - with uphaulages to the mill area. The quarry was owned by Dorothea after 1836 and closed in the late 1890s by which time it employed more than 240 men and produced outputs of more than 5000 tonnes per annum. Some small-scale working continued until the 1940s but the relict remains at the NE of the site survive much as illustrated on the Ordnance Survey 1st edition map (1889).

The northern part of the site includes the remains of the upper quarry pit, three adits, weigh houses and two distinctive spoil mounds. This area is connected via an internal tramway system to the massive eastern slate waste tip that dominates the valley. A steep inclined plane connects the upper level with the processing area. The incline retains a roofless, relict winder house along with associated wagons and cables.

The processing area is connected to the upper quarry pit via a short tunnel orientated N-S that runs adjacent to the incline. A stackyard at the west end of this area has been partly obscured by secondary working and tipping. The processing area retains a longitudinal mill along with a number of ancillary buildings including a smithy, engine house and numerous gwaliau. Records indicate that further archaeological features survive at the W end of the site part buried in slate waste.

The mill is 60m in length by 15m transversely and retains slate slab walls on all sides with the west gable end surviving to full height. The west end of the mill retains an adjoining winder house, in situ drum and brake gear. The winder house is situated at the summit of a substantial exit incline that connects with the Nantlle Railway (CN420) 200m S of the quarry. This was the eastern terminus of the railway prior to the development of Pen yr Orsedd quarry.

The monument is of national importance as part of a group of some of the best-preserved relict slate quarries in the Nantlle Valley. The slate waste tips are an important landform notable for their scale but the quarry remains are also well preserved and retain legible, functional relationships. The quarry retains significant archaeological potential, with a strong probability of the presence of associated archaeological features or deposits.

The scheduled area includes the remains described and the area around them in which further remains might be expected to survive. The designated area is an irregular polygon of 9.748m. The area measures 575m NNW-SSE by 395m transversely and is centred on NGR 250510, 353740.