Coal industry in Wales

The coal industry in Wales has played an important role in the Industrial Revolution in Wales. Coal mining expanded in the eighteenth century to provide fuel for the blast furnaces of the iron and copper industries that were expanding in South Wales. The industry had reached large proportions by the end of that century, and then further expanded to supply steam-coal for the steam vessels that were beginning to trade around the world. The Cardiff Coal Exchange set the world price for steam-coal and Cardiff became a major coal-exporting port. The South Wales Coalfield was at its peak in 1913 and was one of the largest coalfields in the world. It remained the largest coalfield in Britain until 1925. The supply of coal dwindled, and pits closed in spite of a UK-wide strike against closures. The last deep mine in Wales, Tower Colliery, closed in 2008, after thirteen years as a co-operative owned by its miners.

The South Wales Coalfield was not the only coal mining area of the country. There was a sizeable industry in Flintshire and Denbighshire in northeast Wales, and coal was also mined in Anglesey.

The South Wales Coalfield extends from parts of Pembrokeshire and Carmarthenshire in the west, through Swansea, Neath Port Talbot, Bridgend County Borough, Rhondda Cynon Taf, Merthyr Tydfil, Caerphilly County Borough and Blaenau Gwent to Torfaen in the east. The rocks comprising this area were laid down during the Upper Carboniferous era. At that time warm seas invaded much of southern and northeastern Wales, coral reefs flourished and were laid down as limestone deposits. In South Wales particularly, extensive swamps developed where tree-size clubmosses and ferns grew. The decay of this vegetation as it died formed peat which became buried over the ensuing millennia by other sediments. Over long periods of time, the peat was consolidated and converted by the pressure of overlying layers into seams of coal. Although thinner than the original peat layers, some of the coal deposits in South Wales are of great thickness.

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