The North Wales Coalfield consists of a narrow strip, only 9 miles across at its widest point, extending from Point of Ayr on the coast to near Oswestry, just across the Shropshire border.  There is a a short gap north of Wrexham caused by the Bala Fault and the coal seams are also found beneath the Dee estuary and re-appear at Parkgate on the Wirral.  Geographically it falls within the counties of Denbighshire, Flintshire and Shropshire..

At Bersham the coal seam lies 387 metres below ground.  Actually there are several coal seams, which were mined from a thickness of 65 centimetres upwards.  There is also a separate section north of Denbigh.

On Anglesey, coal was found in shallow workings in the Malltraeth Marshes and for completeness can be said to be part of the North Wales Coalfield, politically if not geographically.

The output of the remained consistently between 2½ and 3 million tons from 1870 until 1906, after which it increased to 3½ million in 1913. It fell below 3 million in 1932 and gradually to 2½ million in 1940 with a sharp drop to approximately 2 million in 1941.

A report on the Coalfield in the 1950s stated that the reserves of coal were small in quantity, in Flintshire the only remaining colliery, Point of Ayr, was working an unusually favourable field under the Dee Estuiary.  In the main Denbighshire coalfield the strata of the coal bearing rocks dipped rapidly making further development unlikely. However, it continued to state that the mining conditions were fairly good but the further south you go there was a good deal of geological faulting. The NCB budgeted for a constant 2.2 million tons of coal per annum throughout the 1960’s at a cost of £5.3 million in minor reconstruction.

At that time, the six collieries left, Gresford, Llay Main, Point of Ayr, Bersham, Hafod and Ifton were the No.5 Area of the National Coal Board’s, North Western Division with the area headquarters at Llay near Wrexham.

The Coalfield was producing one percent of the Nation’s coal (1953) and 60% was used in North Wales with the rest going to Lancashire, Cheshire and Northern Ireland. Its uses were; industry 40%, households 20%, gasworks 10%, railways 8%, others, 22%.

Llay Main closed in 1966, Hafod and Ifton in 1968, Gresford in 1973. By 1974 only two collieries were working, namely Point of Ayr in the north and Bersham in the middle of the Denbighshire field near Ruabon, with a total output of approximately ½ million tons per annum. Bersham carried on producing coal until after the miners’ strike of 1984/85, the last mine to work in the Denbighshire part of the coalfield it closed in 1986. Followed by the last colliery in North Wales, Point of Ayr in 1996.