Moel Fferna

Slate Quarry

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This PDF is based on a booklet written by the Glyndyfrdwy Womens Institute


"The Chain Bridge" Moel Ferna Slate Mine, Glyndyfrdwy.

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Early working was 'open' but later underground levels were worked. From 1876 the company's solicitors were Guthrie Jones and Jones who dealt with an agreement to search for slate in and under the township of Bonnum within the manor of Rug between, C.H. Wynn and J. Parry Jones and Ed.H. Phillips. A considerable number of people took out £10 shares in the company including the local clergy.

In 1868 there were 150 men employed but by 1883 there were only 10 men employed working an annual output of about 500 tons.

The main 'tramway' was in use by 1868 and was 2' 0" gauge, worked on the balance incline mode, single track with a passing loop at the half way point, heading down the hillside on a N.N.W direction, generally keeping with the lie of the ground but requiring some shallow cuttings and embankments, through a tunnel under the A5 to curve west and level out at the transhipment wharf with the G.W.R siding.

The siding from the standard gauge line came off the down side and the ground-frame was worked by a key on the electric train staff and was under the control of the Carrog station master.


The private siding was maintained by the G.W.R but at the slate company's expense. Track work on the tramway was a mixture of 15lb per yard, flat bottom and bridge rail, spiked to wooden sleepers, while internal and tip rails were even lighter. Remains would suggest wagons were wooden frames and bodied also steel bodies. (the latter may have been utilised on old wood frames).

The stock movements were made by workers at the quarry except where controlled on the incline but horses may have been used.  The haulage rope would certainly have been 'grass' rope in the early years, later being replaced with wire rope, some of which is still evident today.

The drum house was somewhat unusual, situated above and behind the incline top, housing the horizontal sheaves with a connecting rod to the brake cabin.


Work had ceased by 1890 but restarted five years later, when a small water powered mill was opened on the exchange wharf near the foot of the incline. This was fed by a dam constructed along-side and to the west of the passing loop.

In the accounts for April 1925 money was spent 'rebuilding at slate wharf' - Labour £15, Materials £20.

In June 1929 - £25 on rails, fishplates and keys. £15 on sleepers and £30 on a winding drum.


By the 1900's the quarry was in the hands of the 'Corwen Slate Quarry Co' and output had risen to 1700 tons. A new mill was built at the quarry in 1904 powered by a 12hp Blackstone oil engine and in 1909 a Hornsby 40 hp gas engine was employed to "supply forced air", also, an unusual large reciprocating oil engine shot-saw regarded as a rarity in Welsh slate mining.

With the installation of the internal combustion engines additional workings for the tramway wagons were to haul fuel up to the quarry. By the 1930's only slab slate was produced.



From the company stock book for December 1933:-


Stock gross value = £437 - 6s - 10d.

Sales in Dec = £144 - 17s - 11d, but the 'Corwen Quarry' employing 152 men had closed in May 1932.


In the last years a rough and very steep road led up to the workings but presumably not for slate shipment.

Today the quarry lies open to the wildlife, birds of prey nest safely up in the crags while nature, very gradually, attempts to soften mans industry.


Above ground remains as of 2010.


Many buildings remain in various stages of dilapidation. These include dressing sheds, a mill containing remnants of overhead shafting etc and a motor room. Traces of sand saw installations can be seen in places, including discarded blades and the associated drainage.


Remains of the shot saw installation are clearly visible, together with machinery mounting plinths and saw carriage.


Other artefacts include a compressed gas or air cylinder, piping, a partially buried vessel and remains of a number of wagons and rail.


The main incline top is interesting as it had horizontal sheaves. Much of the mechanism remains in place including the sheaves, brake rod, handle, a ratchet device, table and lengths of wire rope.


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Above is an  extract from the GWR 1924 report relating to the Corwen Slate Quarry.

The Penarth or Corwen Quarry

There are three main types, or categories, into which slate is graded. The oldest 'Cambrian', is found in the Penrhyn -  Dinorwic and Nantlle area, then the 'Ordovician' around Blaenau Ffestiniog and Ffestiniog, finally the 'Silurian' which lies in the Corwen and Llangollen area. The site of the Penarth quarry lies just over a mile to the east of Corwen, above and south of the A5 and near 'Pen Y Grog' in the Berwyn range.