Wenlockian Stage

(also Wenlock stage; named after the city of Wenlock, Shropshire, Great Britain), the second stage from the bottom of the Silurian system. It was identified in 1833 by the British geologist R. Murchison. The type section is composed of aleurolites, argillites, ballstone, and laminated and biohermal limestones with benthic fauna and graptolites.

The Wenlockian stage is subdivided into eight graptolitic zones, of which the C. centrifugus zone is the bottommost and the P. ludensis zone is the uppermost. Deposits of the Wenlockian stage are widely distributed in European countries (Czechoslovakia, the German Democratic Republic, and Poland), North Africa, North America, Australia, and the USSR. In the USSR, Wenlockian deposits are characterized by the greatest completeness in the Baltic region, Podolia, the Urals, the northern part of the Siberian Platform, Kazakhstan, and Middle Asia (seeSILURIAN SYSTEM [PERIOD]).