The South Wales Coalfield

The South Wales Coalfield is a large region of south Wales that is rich with coal deposits.
The South Wales Coalfield lies in parts of the unitary authorities of Carmarthenshire, Swansea, Neath Port Talbot, Bridgend, Rhondda Cynon Taf, Vale of Glamorgan, Merthyr Tydfil, Cardiff, Caerphilly, Blaenau Gwent, Torfaen and Powys.

It comprises a fully exposed synclinorium with a varying thickness of "coal measures" (Upper Carboniferous / Pennsylvanian) deposits with thick, workable seams in the lower parts and generally thinner and sparser seams in the upper parts, together with a development of sandstones (Pennant Sandstone). See also the Geology of South Wales. These sandstones have been much used in building construction (including the characteristic terraces of former miners' houses) and give rise to bleak uplands rising 300-600 metres above sea level between the steep-sided valleys in which most deep mines were developed.
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