(also Llandovery stage; named after the population center of Llandovery, county of Carmarthenshire, Wales, Great Britain), the first stage from the bottom of the Silurian system. It was identified in 1859 by R. Murchison. The type section is composed of carbonate sediments, primarily with benthic fauna and occasional graptolites.
It is divided into the lower, middle, and upper Llandoverian and 11 graptolitic zones bounded beneath by the Monograptus persculptus zone and above by the M. crenulatus zone. Deposits of the Llandoverian stage are widely distributed in the countries of Western Europe (France, Sweden, the Federal Republic of Germany), North Africa, North America, and the USSR, where the stage is characterized by the greatest paleontological completeness in the Baltic region, the Siberian Platform, the Urals, Middle Asia, Kazakhstan, and the Northeast.