Pembrokeshire Coalfield Pembrokeshire Coalfield The Pembrokeshire Coalfield in West Wales is one of the smallest British coalfields, but continuously worked from the 14th to 20th centuries. The main coalfield extends from Saundersfoot on Carmarthen Bay westwards to Broad Haven on St Brides Bay. A small detached portion of the field is centred on Newgale on St Brides Bay. The coalfield is in effect the westernmost extension of the South Wales Coalfield though it is separated from the main body of that field by Carmarthen. Coal seams within the Pembrokeshire Coalfield are traditionally referred to as veins. The following sequence is recognised in
Pembrokeshire to its proximity to the relatively warm Atlantic Ocean. Inland, average temperatures tend to fall 0.5 °C for each 100 metres increase in height. The air pollution rating of Pembrokeshire is "Good", the lowest rating. The rocks in the county were formed between 600 and 290 million years ago. More recent rock formations were eroded when sea levels rose 80 million years ago, at the end of the Cretaceous Period. Around 60 million years ago, the Pembrokeshire landmass emerged through a combination of uplift and falling sea levels; the youngest rocks, from the Carboniferous Period, contain the Pembrokeshire Coalfield. The