The Wenlock Epoch (sometimes referred to as the Wenlockian) is the second epoch of the

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

. It is preceded by the Llandovery Epoch and followed by the

Ludlow Epoch In the geological timescale, the Ludlow Epoch (from 427.4 ± 0.5 million years ago to 423.0 ± 2.3 million years ago) occurred during the Silurian Period, after the end of the Homerian Age. It is named for the town of Ludlow in Shropshire, Engl ...

. Radiometric dates constrain the Wenlockian between and million years ago.

Naming and history

The Wenlock is named after Wenlock Edge, an outcrop of rocks near the town of

Much Wenlock Much Wenlock is a market town and Civil parishes in England, parish in Shropshire, England; it is situated on the A458 road between Shrewsbury and Bridgnorth. Nearby, to the north-east, is the Ironbridge Gorge and Telford. The civil parish incl ...

Shropshire Shropshire (; abbreviated SalopAlso used officially as the name of the county from 1974–1980. The demonym for inhabitants of the county "Salopian" derives from this name.) is a Ceremonial counties of England, ceremonial county in the West M ...

( West Midlands,

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

). The name was first used in the term "Wenlock and

Dudley Dudley ( , ) is a market town in the West Midlands, England, southeast of Wolverhampton and northwest of Birmingham. Historically part of Worcestershire, the town is the administrative centre of the Metropolitan Borough of Dudley. In the ...

rocks" by Roderick Murchison in 1834 to refer to the

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s and underlying

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

s 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.

Definition and subdivision

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

GSSP A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. ...

) of the Sheinwoodian. The end is defined as the base (or

) of the Gorstian. 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.

References

*02 Geological epochs {{Geochronology-stub