Geology of South Wales

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South Wales is an area with many features of outstanding interest to Geologists.

This varied and accessible region has provided a written record of Geological interest going back to the 1100s when Giradus Cambrensis noted pyritous shales near Newport. Some of the first published representations of fossils were those of fossil plants taken from Coal Measures near Neath (Gibson late 1600s).The Great British geologists Adam Sedgwick and Roderick Murchison did fundamentally important work in South Wales on Red Sandstone and the underlying rocks.In the first volume of memoirs (1835)published by The Geological Survey was a concpectus of the geology of South Wales which set a template for all future work. The geology of South Wales was central to the massive contribution Wales made to theIndustrial Revolution. Pembrokeshire has outcrops of both Pre-Cambrian and Cambrian Rocks.

A notable feature of the Ordovician System is a major downwarp known as the Welsh geosyncline.

Silurian rocks are widely distributed in South Wales and are well diplayed on the Cardiganshire coast.

Carboniferous Limestone outcrops in south Pembrokeshire, Gower, the Vale of Glamorgan and north and east sides of the coalfield.

One of the geologically rarities of South Wales is the coastline of Ogmore-by-Sea and Southerndown, as it made of cliffs composed of Sutton stone; a very rare freestone that is a banded mixture of lias limestone which contains large elements of carboniferous limestone. Sutton stone has always been highly regarded, as as well as being used in construction throughout the Vale of Glamorgan was also shipped over the Bristol Channel to North Devon and North Cornwall as both are deficient in limestone.

A major geological feature of the Upper Carboniferous sub peroid in South Wales is The South Wales Coalfield.The Rocks comprising this important area were laid down during the Westphalian Geological Series/epoch,314 to 308 Million years ago (Ma) Approx. This Westphalian succession includes a sequence with a thickness of more than 1800m in the west.The coal measures were laid down on a low lying water logged plain with peat mires immediately South of an ancient Geological feature known as the Wales -London-Brabant High.