Llandovery Beds

Llandovery Beds, a series of sandstones, conglomerates, and shales, well exposed in the neighbourhood of Llandovery, Carmarthenshire (whence they take their name), and covering a great part of South Wales and of the shores of Cardigan Bay. South-east of Bala Lake they rest unconformably on the Bala beds, and they form passage beds from the Ordovician (q.v.), or Lower Silurian, to the Silurian proper, being divided into a Lower and Upper series by an unconformity. The Lower Llandovery series is about 1,000 feet thick, andthe Upper about 1,500 feet. The latter is also known as the May Hill series from its occurrence at May Hill, Gloucestershire. The prevalence of the brachiopod genus Pentamerus throughout the two series has caused them to be sometimes termed the Pentamerus beds, P. (stricklandinia) lens being the characteristic species of the Lower, P. oblongus together with Strophomena, Atrypa reticularis (the earliest known echinoid), Palcechinus, and many trilobites, including Calymene Blumenbachii of the Upper series. The quartz-rock of the Lickey Hills, Worcestershire, is of Upper Llandovery age.