llandeilo group

Century Dictionary and Cyclopedia

1. n. A division of the Lower Silurian, first described by Murchison as occurring at Llandeilo in Carmarthenshire, Wales, and also found in Pembrokeshire and Radnorshire. The group consists of dark-colored flags, sandstones, and shales, and is between 2,000 and 3,000 feet thick. It contains many of the characteristic fossils of the lowest division of the Silurian, especially trilobites of genera included in Barrande's “primordial fauna,” such as Asaphus, Calymene, and Ogygia.

GNU Webster's 1913

1. (Geol.) A series of strata in the lower Silurian formations of Great Britain; -- so named from Llandeilo in Southern Wales. See Chart of geology.