Editing Silurian (section)

==Climate and sea level==
The Silurian period was once believed to have enjoyed relatively stable and warm temperatures, in contrast with the extreme glaciations of the Ordovician before it and the extreme heat of the ensuing Devonian; however, it is now known that the global climate underwent many drastic fluctuations throughout the Silurian,<ref name="Yan2022EarlySilurianClimateChange">{{cite journal |last1=Yan |first1=Guanzhou |last2=Lehnert |first2=Oliver |last3=Männik |first3=Peep |last4=Calner |first4=Mikael |last5=Luan |first5=Xiaocong |last6=Gong |first6=Fanyi |last7=Li |first7=Lixia |last8=Wei |first8=Xin |last9=Wang |first9=Guangxu |last10=Zhan |first10=Renbin |last11=Wu |first11=Rongchang |date=15 November 2022 |title=The record of early Silurian climate changes from South China and Baltica based on integrated conodont biostratigraphy and isotope chemostratigraphy |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018222004151 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=606 |page=111245 |doi=10.1016/j.palaeo.2022.111245 |bibcode=2022PPP...60611245Y |s2cid=252504361 |access-date=8 December 2022}}</ref><ref name="GambacortaMenichettiTrinciantiTorricelli" /> evidenced by numerous major carbon and oxygen isotope excursions during this geologic period.<ref name="YoungEtAl2020PPP">{{cite journal |last1=Young |first1=Set A. |last2=Benayoun |first2=Emily |last3=Kozik |first3=Nevin P. |last4=Hints |first4=Olle |last5=Martma |first5=Tõnu |last6=Bergström |first6=Stig M. |last7=Owens |first7=Jeremy D. |date=15 September 2020 |title=Marine redox variability from Baltica during extinction events in the latest Ordovician–early Silurian |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=554 |page=109792 |doi=10.1016/j.palaeo.2020.109792 |bibcode=2020PPP...55409792Y |s2cid=218930512 |doi-access=free }}</ref><ref>{{cite journal |last1=Sproson |first1=Adam D. |date=15 February 2020 |title=Pacing of the latest Ordovician and Silurian carbon cycle by a ~4.5 Myr orbital cycle |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018219308867 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=540 |page=109543 |doi=10.1016/j.palaeo.2019.109543 |bibcode=2020PPP...54009543S |s2cid=213445668 |access-date=8 December 2022}}</ref><ref name="TrotterEtAl2016PPP" /> Sea levels rose from their [[Hirnantian]] low throughout the first half of the Silurian; they subsequently fell throughout the rest of the period, although smaller scale patterns are superimposed on this general trend; fifteen high-stands (periods when sea levels were above the edge of the continental shelf) can be identified, and the highest Silurian sea level was probably around {{convert|140|m|0}} higher than the lowest level reached.<ref name=Munnecke2010/>

During this period, the [[Earth]] entered a warm [[greenhouse]] phase, supported by high CO<sub>2</sub> levels of 4500 ppm, and warm shallow seas covered much of the equatorial land masses.<ref name="Chaloner2003">{{cite journal |last1=Chaloner |first1=William G. |title=The role of carbon dioxide in plant evolution |journal=Evolution on Planet Earth |date=2003 |pages=65–83 |doi=10.1016/B978-012598655-7/50032-X|isbn=9780125986557 }}</ref> Early in the Silurian, [[glacier]]s retreated back into the [[South Pole]] until they almost disappeared in the middle of Silurian.<ref name="GambacortaMenichettiTrinciantiTorricelli">{{cite journal |last1=Gambacorta |first1=G. |last2=Menichetti |first2=E. |last3=Trincianti |first3=E. |last4=Torricelli |first4=S. |title=The Silurian climatic transition recorded in the epicontinental Baltica Sea |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=March 2019 |volume=517 |pages=16–29 |doi=10.1016/j.palaeo.2018.12.016|bibcode=2019PPP...517...16G |s2cid=135118794 }}</ref> Layers of broken shells (called [[coquina]]) provide strong evidence of a climate dominated by violent storms generated then as now by warm sea surfaces.<ref>{{cite journal |last1=Nealon |first1=T. |last2=Williams |first2=D. Michael |title=Storm-influenced shelf deposits from the silurian of Western Ireland: A reinterpretation of deep basin sediments |journal=Geological Journal |date=30 April 2007 |volume=23 |issue=4 |pages=311–320 |doi=10.1002/gj.3350230403}}</ref>

=== Perturbations ===
The climate and [[carbon cycle]] appear to be rather unsettled during the Silurian, which had a higher frequency of isotopic excursions (indicative of climate fluctuations) than any other period.<ref name=Munnecke2010/> The [[Ireviken event]], [[Mulde event]], and [[Lau event]] each represent isotopic excursions following a minor mass extinction<ref>{{Cite journal| last1 = Samtleben | first1 = C.| last2 = Munnecke | first2 = A.| last3 = Bickert | first3 = T.| title = Development of facies and C/O-isotopes in transects through the Ludlow of Gotland: Evidence for global and local influences on a shallow-marine environment| journal = Facies| volume = 43| pages = 1–38| year = 2000| issue = 1| doi = 10.1007/BF02536983| bibcode = 2000Faci...43....1S| s2cid = 130640332}}</ref> and associated with rapid sea-level change. Each one leaves a similar signature in the geological record, both geochemically and biologically; pelagic (free-swimming) organisms were particularly hard hit, as were [[brachiopods]], [[corals]], and [[trilobites]], and extinctions rarely occur in a rapid series of fast bursts.<ref name=Munnecke2010/><ref name="TrotterEtAl2016PPP">{{cite journal |last1=Trotter |first1=Julie A. |last2=Williams |first2=Ian S. |last3=Barnes |first3=Christopher R. |last4=Männik |first4=Peep |last5=Simpson |first5=Andrew |title=New conodont δ18O records of Silurian climate change: Implications for environmental and biological events |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=February 2016 |volume=443 |pages=34–48 |doi=10.1016/j.palaeo.2015.11.011|bibcode=2016PPP...443...34T }}</ref> The climate fluctuations are best explained by a sequence of glaciations, but the lack of [[tillite]]s in the middle to late Silurian make this explanation problematic.<ref name="Calner2008">{{cite book |last1=Calner |first1=Mikael |title=Mass Extinction |chapter=Silurian global events – at the tipping point of climate change |date=2008 |pages=21–57 |doi=10.1007/978-3-540-75916-4_4|isbn=978-3-540-75915-7 }}</ref>