Maenofferen Slate Quarry is a substantial and entirely underground slate quarry in Blaenau Ffestiniog perched 1300 feet above sea level in the Welsh Mountains to the west of the Town. Maenofferen holds a significant place in the history of the slate industry in North Wales as the quarry provides considerable information for understanding the development and process of underground slate extraction, the above ground processing, and the onward transport of the slate via tramways and railways to the worldwide markets. Situated near the village of Blaenau Ffestiniog, in Gwynedd, Wales, Maenofferen Quarry has a rich heritage that spans over two centuries.
Shortly after 1800, Maenofferen was first worked for slate by men from the nearby Diphwys quarry and it formed part of the open pit workings in the area. These endeavours were not overly successful as transportation of the slate was problematic. It was not until the Maenofferen Slate Quarry Company Ltd formed in 1861, when the land and existing quarry was leased from the owner Lord Newborough, did the quarry begin to see success. The quarry proved very successful, its output increased from 397 tons in 1861 to 8,600 tons in 1882, the fifth largest producer in the Ffestiniog area. In 1897 it employed 429 people and had a production output of nearly 14,000 tonnes, with almost half of those working underground. Two water driven mills were constructed on site, which contained 50 table saws and as many trimmers. In the 1890s electricity was introduced, and a hydroelectric station was installed in 1918. In 1928 Maenofferen purchased the Rhiwbach quarry, continuing to work it and use its associated Tramway until 1953.
Like all slate quarries in North Wales, they experience a decline in demand for slate post World War 2 due to new roof materials becoming available. By 1972 the workforce had fallen to 60 men with an annual output of 1,200 tons. The quarry was purchased by the Greaves Family who owned the nearby Llechwedd quarry in 1975 together with Bowydd, which also incorporated the old Votty workings. During this time, they pioneered the use of wire saws in the extraction of material underground. Underground production at Maenofferen ceased during November 1999 and with it the end of large-scale underground working for slate in north Wales, the quarry shut for good in 2001. Production of slate recommenced on the combined Maenofferen site and consists of “untopping” the underground workings to recover slate from the supporting pillars of the chambers. Material recovered from the quarry tips will also be recovered for crushing and subsequent use. Maenofferen forms part of the UNESCO North Wales Slate area.
Due to the position of Maenofferen, transportation from the quarry was an ongoing issue during its operation. During the early years, the Ffestiniog Railway as the quarry’s major transport outlet for its products, but there was no direct connection from it to the Ffestiniog’s terminus at Duffws. Instead slate was sent via the Rhiwbach Tramway which ran through the quarry, incurring additional shipping costs that rival quarries did not have to bear. In 1908 the company leased wharf space at Minffordd, installing turntables and siding to allow finished slates to be transshipped to the standard gauge railway there. In 1920 the company solved its high shipping costs by building a new incline connecting its mill to the Votty & Bowydd quarry and reaching agreement to ship its products via that company’s incline connection to the Ffestiniog Railway at Duffws.
When the Ffestiniog Railway ceased operation in 1946, Maenofferen leased a short length of the railway’s tracks between Duffws station and the interchange with the LMS railway, west of Blaenau Ffestiniog. The slate trains continued to run over this section until 1962 and the line closed, This meant that Maenofferen was the last slate quarry to use any part of the Ffestiniog Railway’s route. The No 2 Incline down to the Rwiwbach Tramway was still operational in 1976, and was the last self acting incline in operation. From 1962 slate was shipped from the quarry by road, although the internal quarry tramways including stretches of the Rhiwbach tramway continued in use until at least the 1980s.
The underground areas of the quarry now lays abandoned and present a remarkable insight into how a large underground slate quarry was worked. Recent years have seen the owners of Llechweld Quarry run underground tours through some of the works.