Denbighshire Coalfield

The Denbighshire Coalfield in north-east Wales is one of the smaller British coalfields. It extends from near Caergwrle in the north, southwards through Wrexham, Ruabon and Rhosllanerchrugog to Chirk in the south. A small part extends into Shropshire around Oswestry. Beyond Caergwrle the coal-bearing strata continue northwards as the Flintshire Coalfield; ^[1] Together the two coalfields are known as the North Wales Coalfield.^[2] The last deep mine to operate in the coalfield was Bersham Colliery which closed in 1986. Prior to this time, as many as 38 collieries had been in operation across the area, with a peak output in excess of 2.6 million tons, and giving employment at the height of production to some 12,000 men.^[3]

Several coal seams are named in the sequence. All of the seams occur within the Bettisfield Formation with the exception of the Morlas which occurs in the Coed-yr-Allt Formation. The seams are listed stratigraphically with the uppermost (youngest) at the head of the list and the lowermost (oldest) at the foot.^[4]

• Morlas
• Bersham Yard Group; from Alpha (or Alpha Rider) through Beta Rider, Beta and Gamma to Delta (or Delta Bench)
• Upper Stinking
• Warras
• Lower Stinking (known as Brassy at former Moreton Hall Colliery)
• Powell
• Hollin
• Crank
• Quaker
• Main (was known as Six Foot at Quinta Colliery, Bottoms at Preesgwyn Colliery, Bind and Bench at Moreton Hall Colliery and Yard in the Oswestry area)
• Crown
• Upper Red
• Lower Red
• Cannel
• Fireclay Group (includes Stone, Half Yard, Firedamp, Bottom Four Foot and Two Foot seams)
• Nant
• Ruabon Yard
• Premier
• Llwyneinion Half Yard
• Chwarelau

The Smiths seam, which lies between the Main seam and the Lower Stinking seam was known as the Upper Yard at Moreton Hall Colliery and Rover at Oswestry Colliery.

References

1. ^ British Geological Survey, 2007 Bedrock Geology: UK South, 1:625,000 scale geological map (5th edn), BGS, Keyworth, Notts
2. ^ http://northwalesminers.com/geology.htm
3. ^ http://www.wrexham.gov.uk/english/heritage/bersham_colliery.htm
4. ^ British Geological Survey 1:50,000 geological map sheet nos 121 Wrexham, 137 Oswestry, BGS, Keyworth, Notts

Coordinates: 53°03′03″N 3°00′34″W / 53.0507°N 3.0094°W / 53.0507; -3.0094