Redrawing the geological map of South Wales (lecture)

Professor John Cope, National Museum of Wales

T. Neville George Medal lecture

A keen Swansea extramural class in the mid-1970s demanded more field-work. A geological mapping project was suggested, but had to be suitable for beginners and within an hour’s drive. The area finally selected was south of Carmarthen where the 1 inch Geological Survey map showed Ordovician Arenig Series unconformably overlain by Old Red Sandstone. Both had several formations and there were also some Ordovician igneous rocks. Initial mapping of the basal ORS unconformity then progressed into the Ordovician outcrop, proving the Survey succession incorrect. A series of totally unexpected stratigraphical and structural results ensued together with many exciting new fossils.