Sheinwoodian

The Wenlock (sometimes referred to as the Wenlockian) is the second series of the Silurian. It is preceded by the Llandovery series and followed by the Ludlow. Radiometric dates constrain the Wenlockian between 433.4 and 427.4 million years ago.

The Wenlock is named after Wenlock Edge, an outcrop of rocks near the town of Much Wenlock in Shropshire (West Midlands, United Kingdom). The name was first used in the term "Wenlock and Dudley rocks" by Roderick Murchison in 1834 to refer to the limestones and underlying shales that underlay what he termed the "Ludlow rocks". He later modified this term to simply the "Wenlock rocks" in his book, The Silurian System in 1839.

The Wenlock's beginning is defined by the lower boundary (or GSSP) of the Sheinwoodian. The end is defined as the base (or GSSP) of the Gorstian.

The Wenlock is divided into the older Sheinwoodian and the younger Homerian stage. The Sheinwoodian lasted from 433.4 to 430.5 million years ago. The Homerian lasted from 430.5 to 427.4 million years ago.

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