| Wenlock | |
| Color: | Wenlock |
| Time Start: | 433.4 |
| Time Start Uncertainty: | 0.8 |
| Time End: | 427.4 |
| Time End Uncertainty: | 0.5 |
| Caption Map: | Map of Earth as it appeared 430 million years ago during the Wenlock epoch, Homerian stage |
| Timeline: | Silurian |
| Name Formality: | Formal |
| Name Accept Date: | 1980[1] |
| Celestial Body: | earth |
| Usage: | Global (ICS) |
| Timescales Used: | ICS Time Scale |
| Chrono Unit: | Epoch |
| Strat Unit: | Series |
| Timespan Formality: | Formal |
| Lower Boundary Def: | Imprecise. Currently placed between acritarch biozone 5 and last appearance of Pterospathodus amorphognathoides. See Llandovery for more info. |
| Lower Gssp Candidates: | None |
| Lower Def Candidates: | A conodont boundary (Ireviken datum 2) which is close to the murchisoni graptolite biozone. |
| Lower Gssp Location: | Hughley Brook, Apedale, U.K. |
| Lower Gssp Accept Date: | 1980 |
| Upper Boundary Def: | FAD of the Graptolite Saetograptus (Colonograptus) varians |
| Upper Gssp Location: | Pitch Coppice, Ludlow, U.K. |
| Upper Gssp Accept Date: | 1980 |
The Wenlock (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 and million years ago.[2]
The Wenlock is named after Wenlock Edge, an outcrop of rocks near the town of Much Wenlock in Shropshire (West Midlands, United Kingdom).[3] 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".[4] He later modified this term to simply the "Wenlock rocks" in his book, The Silurian System in 1839.[5]
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.[6]
The Wenlock is divided into the older Sheinwoodian and the younger Homerian stage. The Sheinwoodian lasted from to million years ago. The Homerian lasted from to million years ago.