Geology of Wales - History of Geological Study

History of Geological Study

South Wales has a written record of geological interest going back to the 12th century when Giraldus Cambrensis noted pyritous shales near Newport. George Owen in 1603 correctly identified the stratigraphic relationship between the Carboniferous Limestone and the Coal Measures. Some of the first published representations of fossils were those of fossil plants taken from coal measures near Neath (Gibson late 17th century).

In the mid-19th century, two prominent geologists, Roderick Murchison and Adam Sedgwick used their studies of the geology of Wales to establish certain principles of stratigraphy and palaeontology. They did fundamental work on the Old Red Sandstone but are remembered more for their work on the lower Palaeozoic sequence. It was Sedgwick who established the Cambrian system and Murchison first described the Silurian, naming it for the ancient Silures tribe which occupied mid Wales. An overlap between the two systems as mapped led eventually to protracted dispute between the two erstwhile collaborators. After their deaths, Charles Lapworth erected the Ordovician system (again named for an ancient tribe of northwest Wales, the Ordovices), to account for the sequence of rocks at the heart of the controversy.

More recently two locations in mid Wales have been selected to globally define stages of the Silurian period. Cefn-cerig Road near Cefn-cerig Farm, Llandovery, is the location of the Global Boundary Stratotype Section and Point (GSSP) which marks the boundary between the Aeronian and Telychian stages of the Silurian period on the geologic time scale. Similarly Trefawr Track, a forestry road north of Cwm-coed-aeron Farm, Llandovery, is the location of the GSSP marking the boundary between the Rhuddanian and Aeronian stages. Both GSSPs were ratified in 1984. :See main articles on Cefn-cerig Road and Trefawr Track.