Wenlock Epoch

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Wenlock
433.4 ± 0.8 – 427.4 ± 0.5 Ma
Hughley Brook, Apedale, U.K.
52°34′52″N 2°38′20″W / 52.5811°N 2.6389°W / 52.5811; -2.6389
Lower GSSP ratified1980[4]
Upper boundary definitionFAD of the Graptolite Saetograptus (Colonograptus) varians
Upper boundary GSSPPitch Coppice, Ludlow, U.K.
52°21′33″N 2°46′38″W / 52.3592°N 2.7772°W / 52.3592; -2.7772
Upper GSSP ratified1980[4]

The Wenlock Epoch (sometimes referred to as the Wenlockian) is the second epoch of the Silurian. It is preceded by the Llandovery Epoch and followed by the Ludlow Epoch. Radiometric dates constrain the Wenlockian between 432.9 and 426.7 million years ago.[5]

Naming and history

The Wenlock is named after Wenlock Edge, an outcrop of rocks near the town of Much Wenlock in Shropshire (West Midlands, United Kingdom).[6] 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".[7] He later modified this term to simply the "Wenlock rocks" in his book, The Silurian System in 1839.[8]

Definition and subdivision

The Wenlock's beginning is defined by the lower boundary (or

GSSP) of the Gorstian.[9]

The Wenlock is divided into the older Sheinwoodian and the younger Homerian stage. The Sheinwoodian lasted from 432.9 to 430.6 million years ago. The Homerian lasted from 430.6 to 426.7 million years ago.[5]

References