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Wenlock Epoch - Wikipedia

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Wenlock

433.4 ± 0.8 – 427.4 ± 0.5 Ma

PreꞒ

Ꞓ

A map of Earth as it appeared 430 million years ago during the Wenlock Epoch, Homerian Age

Chronology

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Paleozoic

Silurian

←

←

Mulde event^[1]

←

Ireviken event^[2]

Subdivision of the Silurian according to the ICS, as of 2023.^[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, U.K.
52°34′52″N 2°38′20″W / 52.5811°N 2.6389°W

Lower GSSP ratified

1980^[4]

Upper boundary definition

FAD of the Graptolite Saetograptus (Colonograptus) varians

Upper boundary GSSP

Pitch Coppice, Ludlow, U.K.
52°21′33″N 2°46′38″W / 52.3592°N 2.7772°W

Upper GSSP ratified

1980^[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 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

^ 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.
^ 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.
^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. September 2023. Retrieved December 16, 2024.
^ ^a ^b ^c Holland, C. (1982). "The State of Silurian Stratigraphy" (PDF). Episodes. 1982: 21–23. Retrieved 11 December 2020.
^ ^a ^b "International Chronostratigraphic Chart 2013/01" (PDF). International Commission on Stratigraphy. Retrieved 10 July 2013.
^ Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). A Geologic Time Scale 2004. ISBN 9780521786737.
^ 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.
^ Murchison R.I. (1839). The Silurian System. Murray. p. 208.
^ The Geologic Time Scale 2012. Elsevier Science Ltd. 14 August 2012. ISBN 978-0-444-59425-9.

Silurian Period

Llandovery	Wenlock	Ludlow	Pridoli
Rhuddanian Aeronian Telychian	Sheinwoodian Homerian	Gorstian Ludfordian

Geological history of Earth

Cenozoic Era
(present–66.0 Ma)

Quaternary (present–2.58 Ma)	Holocene (present–11.7 ka) Pleistocene (11.7 ka–2.58 Ma)
Neogene (2.58–23.0 Ma)	Pliocene (2.59–5.33 Ma) Miocene (5.33–23.0 Ma)
Paleogene (23.0–66.0 Ma)	Oligocene (23.0–33.9 Ma) Eocene (33.9–56.0 Ma) Paleocene (56.0–66.0 Ma)

Mesozoic Era
(66.0–252 Ma)

Cretaceous (66.0–145 Ma)	Late (66.0–100 Ma) Early (100–145 Ma)
Jurassic (145–201 Ma)	Late (145–164 Ma) Middle (164–174 Ma) Early (174–201 Ma)
Triassic (201–252 Ma)	Late (201–237 Ma) Middle (237–247 Ma) Early (247–252 Ma)

Paleozoic Era
(252–539 Ma)

Permian (252–299 Ma)	Lopingian (252–260 Ma) Guadalupian (260–272 Ma) Cisuralian (272–299 Ma)
Carboniferous (299–359 Ma)	Pennsylvanian (299–323 Ma) Mississippian (323–359 Ma)
Devonian (359–419 Ma)	Late (359–383 Ma) Middle (383–393 Ma) Early (393–419 Ma)
Silurian (419–444 Ma)	Pridoli (419–423 Ma) Ludlow (423–427 Ma) Wenlock (427–433 Ma) Llandovery (433–444 Ma)
Ordovician (444–485 Ma)	Late (444–458 Ma) Middle (458–470 Ma) Early (470–485 Ma)
Cambrian (485–539 Ma)	Furongian (485–497 Ma) Miaolingian (497–509 Ma) Series 2 (509–521 Ma) Terreneuvian (521–539 Ma)

Proterozoic Eon
(539 Ma–2.5 Ga)

Neoproterozoic (539 Ma–1 Ga)	Ediacaran (539–635 Ma) Cryogenian (635–720 Ma) Tonian (720 Ma–1 Ga)
Mesoproterozoic (1–1.6 Ga)	Stenian (1–1.2 Ga) Ectasian (1.2–1.4 Ga) Calymmian (1.4–1.6 Ga)
Paleoproterozoic (1.6–2.5 Ga)	Statherian (1.6–1.8 Ga) Orosirian (1.8–2.05 Ga) Rhyacian (2.05–2.3 Ga) Siderian (2.3–2.5 Ga)