Wenlock Epoch

Short description: 2nd Series (Epoch) of the Silurian

Wenlock

433.4 ± 0.8 – 427.4 ± 0.5 Ma

PreЄ

Chronology

Silurian graphical timeline

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Paleozoic

Silurian

Late O

Llandovery

95%;|Wenlock}}

90%;|Ludlow}}

Přídolí

Early D

Rhuddanian

Aeronian

Telychian

Sheinwoodian

Homerian

Gorstian

Ludfordian

Lau event

Mulde event[1]

Ireviken event[2]

Subdivision of the Silurian according to the ICS, as of 2021.[3]
Vertical axis scale: millions of years ago.

Etymology
Name formality| Formal
Name ratified| 1980[4]
Usage information
Celestial body| Earth
Regional usage| Global (ICS)
Time scale(s) used| ICS Time Scale
Definition
Chronological unit| Epoch
Stratigraphic unit| Series
Time span formality| Formal
Lower boundary definition| Imprecise. Currently placed between acritarch biozone 5 and last appearance of Pterospathodus amorphognathoides. See Llandovery for more info.
Lower boundary definition candidates| A conodont boundary (Ireviken datum 2) which is close to the murchisoni graptolite biozone.
Lower boundary GSSP candidate section(s)| None
Lower boundary GSSP| Hughley Brook, Apedale, United Kingdom
[ ⚑ ] 52°34′52″N 2°38′20″W﻿ / ﻿52.5811°N 2.6389°W﻿ / 52.5811; -2.6389
GSSP ratified| 1980[4]
Upper boundary definition| FAD of the Graptolite Saetograptus (Colonograptus) varians
Upper boundary GSSP| Pitch Coppice, Ludlow, United Kingdom
[ ⚑ ] 52°21′33″N 2°46′38″W﻿ / ﻿52.3592°N 2.7772°W﻿ / 52.3592; -2.7772
GSSP ratified| 1980[4]

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 433.4 and 427.4 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 Sheinwoodian. The end is defined as the base (or GSSP) of the Gorstian.[9]

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.[5]

## References

1. ↑ Jeppsson, L.; Calner, M. (2007). "The Silurian Mulde Event and a scenario for secundo—secundo events". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 93 (02): 135–154. doi:10.1017/S0263593300000377.
2. ↑ Munnecke, A.; Samtleben, C.; Bickert, T. (2003). "The Ireviken Event in the lower Silurian of Gotland, Sweden-relation to similar Palaeozoic and Proterozoic events". Palaeogeography, Palaeoclimatology, Palaeoecology 195 (1): 99–124. doi:10.1016/S0031-0182(03)00304-3.
3. ↑ "Chart/Time Scale". International Commission on Stratigraphy. http://www.stratigraphy.org/index.php/ics-chart-timescale.
4. ↑ 4.0 4.1 4.2 Holland, C. (1982). "The State of Silurian Stratigraphy". Episodes 1982: 21-23. https://stratigraphy.org/gssps/files/sheinwoodian-ludfordian.pdf. Retrieved 11 December 2020.
5. ↑ 5.0 5.1 "International Chronostratigraphic Chart 2013/01". International Commission on Stratigraphy. http://www.stratigraphy.org/ICSchart/ChronostratChart2013-01.pdf.
6. ↑ Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). A Geologic Time Scale 2004. ISBN 9780521786737.
7. ↑ Murchison R.I. (1833–1834). "On the Structure and Classification of the Transition Rocks of Shropshire, Herefordshire and part of Wales and on the Lines of Disturbance which have affected that Series of Deposits, including the Valley of Elevation of Woolhope". Proceedings of the Geological Society of London 2 (33): 14. https://archive.org/details/proceedings218331838geol.
8. ↑ Murchison R.I. (1839). The Silurian System. Murray. pp. 208. https://books.google.com/books?id=cKlAAAAAcAAJ&q=murchison+wenlock+limestone&pg=PA209.
9. ↑ The Geologic Time Scale 2012. Elsevier Science Ltd. 14 August 2012. ISBN 978-0-444-59425-9.

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Geological history of Earth

Cenozoic era
(present–66.0 Mya)|

| Quaternary (present–2.588 Mya)|

* Holocene (present–11.784 kya)
* Pleistocene (11.784 kya–2.588 Mya)

|

Neogene (2.588–23.03 Mya)|

* Pliocene (2.588–5.333 Mya)
* Miocene (5.333–23.03 Mya)

Paleogene (23.03–66.0 Mya)|

* Oligocene (23.03–33.9 Mya)
* Eocene (33.9–56.0 Mya)
* Paleocene (56.0–66.0 Mya)

Mesozoic era
(66.0–251.902 Mya)|

| Cretaceous (66.0–145.0 Mya)|

* Late (66.0–100.5 Mya)
* Early (100.5–145.0 Mya)

|

Jurassic (145.0–201.3 Mya)|

* Late (145.0–163.5 Mya)
* Middle (163.5–174.1 Mya)
* Early (174.1–201.3 Mya)

Triassic (201.3–251.902 Mya)|

* Late (201.3–237 Mya)
* Middle (237–247.2 Mya)
* Early (247.2–251.902 Mya)

Paleozoic era
(251.902–541.0 Mya)|

| Permian (251.902–298.9 Mya)|

* Lopingian (251.902–259.8 Mya)
* Guadalupian (259.8–272.3 Mya)
* Cisuralian (272.3–298.9 Mya)

|

Carboniferous (298.9–358.9 Mya)|

* Pennsylvanian (298.9–323.2 Mya)
* Mississippian (323.2–358.9 Mya)

Devonian (358.9–419.2 Mya)|

* Late (358.9–382.7 Mya)
* Middle (382.7–393.3 Mya)
* Early (393.3–419.2 Mya)

Silurian (419.2–443.8 Mya)|

* Pridoli (419.2–423.0 Mya)
* Ludlow (423.0–427.4 Mya)
* Wenlock (427.4–433.4 Mya)
* Llandovery (433.4–443.8 Mya)

Ordovician (443.8–485.4 Mya)|

* Late (443.8–458.4 Mya)
* Middle (458.4–470.0 Mya)
* Early (470.0–485.4 Mya)

Cambrian (485.4–541.0 Mya)|

* Furongian (485.4–497 Mya)
* Miaolingian (497–509 Mya)
* Series 2 (509–521 Mya)
* Terreneuvian (521–541.0 Mya)

Proterozoic eon
(541.0 Mya–2.5 Gya)|

| Neoproterozoic (541.0 Mya–1 Gya)|

* Ediacaran (541.0–~635 Mya)
* Cryogenian (~635–~720 Mya)
* Tonian (~720 Mya–1 Gya)

|

Mesoproterozoic (1–1.6 Gya)|

* Stenian (1–1.2 Gya)
* Ectasian (1.2–1.4 Gya)
* Calymmian (1.4–1.6 Gya)

Paleoproterozoic (1.6–2.5 Gya)|

* Statherian (1.6–1.8 Gya)
* Orosirian (1.8–2.05 Gya)
* Rhyacian (2.05–2.3 Gya)
* Siderian (2.3–2.5 Gya)

Archean eon (2.5–4 Gya)|

| Eras|

* Neoarchean (2.5–2.8 Gya)
* Mesoarchean (2.8–3.2 Gya)
* Paleoarchean (3.2–3.6 Gya)
* Eoarchean (3.6–4 Gya)

|

Hadean eon (4–4.6 Gya)|

|  |

|

kya = thousands years ago. Mya = millions years ago. Gya = billions years ago.
See also: Geologic time scale

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