Rushton, A.W.A., Owen, A.W., Owens, R.M. & Prigmore, J.K. 2000. British Cambrian to Ordovician Stratigraphy. Geological Conservation Review Series No. 18, JNCC, Peterborough, ISBN 1 86107 4727.
The original source material for these web pages has been made available by the JNCC under the Open Government Licence 3.0. Full details in the JNCC Open Data Policy
This small quarry is a valuable source for Llandeilian fossils, in particular trilobites, and is the type locality for the trinucleid Marrolithoides simplex (Williams). It was given by Williams (1948, p. 79) as 'quarry 300 yards W of Wernellyn farm, 1 mile SSE [sic — should read SSW] of Llangadock'. The section is supplementary to those seen in Dynevor Park, at Ffairfâch and in the Meidrim Road section.
The area in which this quarry lies is included on Williams' (1953) map, and it falls within the outcrop of the Middle Llandeilo Flags. It has featured in excursion guides (e.g. Bassett, 1982), but until recently much of the face was obscured by talus. The section was cleared in a joint operation by the Countryside Council for Wales and Cwmdeithas Edward Lhwyd in early 1997, and its condition is now (1999) far better than it has been for many years.
The roadside quarry shows the following section:
| Thickness | |
| 10 m+ | Soft shales |
| 6m | Dark, calcareous flags |
| 2m | Massive, calcareous sandstones |
Fossils are particularly abundant in the calcareous flags and include articulated and fragmentary specimens of the trilobites Ogygiocarella debuchii (Brongniart) and Marrolithoides simplex (Williams)
Acting as a complementary section to others at this horizon, Talar Wen is useful in that it is one of the most accessible and fossiliferous localities at which to study the fauna of the Middle Llandeilo Flags and is certainly the best locality to see the Marrolithoides simplex Beds. It is the type locality for the eponymous trilobite.