Editing Cretaceous (section)

==Etymology and history==
The Cretaceous as a separate period was first defined by Belgian geologist [[Jean Baptiste Julien d'Omalius d'Halloy|Jean d'Omalius d'Halloy]] in 1822 as the ''Terrain Crétacé'',<ref>{{cite journal | author = d’Halloy, d’O., J.-J. | year = 1822 | title = Observations sur un essai de carte géologique de la France, des Pays-Bas, et des contrées voisines |trans-title=Observations on a trial geological map of France, the Low Countries, and neighboring countries | journal = Annales des Mines | volume = 7 | pages = 353–376 | url = https://books.google.com/books?id=c-ocAQAAIAAJ&pg=PA353}}  From page 373:  "La troisième, qui correspond à ce qu'on a déja appelé formation de la craie, sera désigné par le nom de terrain crétacé." (The third, which corresponds to what was already called the "chalk formation", will be designated by the name "chalky terrain".)</ref> using [[stratum|strata]] in the [[Paris Basin]]<ref>{{cite book |trans-title=Great Soviet Encyclopedia |title=Sovetskaya Enciklopediya  |publisher=Sovetskaya Enciklopediya |edition=3rd |pages=vol. 16, p. 50 |year=1974 |location=Moscow |language=ru |no-pp=true |title-link=Great Soviet Encyclopedia}}</ref> and named for the extensive beds of [[chalk]] ([[calcium carbonate]] deposited by the shells of marine [[invertebrate]]s, principally [[coccoliths]]), found in the upper Cretaceous of [[Western Europe]]. The name Cretaceous was derived from the [[Latin]] ''creta'', meaning ''chalk''.<ref>{{cite book|title=Glossary of Geology|publisher=American Geological Institute|edition=3rd|page= 165|year=1972|location=Washington, D.C.}}</ref> The twofold division of the Cretaceous was implemented by [[William Conybeare (geologist)|Conybeare]] and Phillips in 1822. [[Alcide d'Orbigny]] in 1840 divided the French Cretaceous into five ''étages'' (stages): the [[Neocomian]], Aptian, Albian, Turonian, and Senonian, later adding the ''Urgonian'' between Neocomian and Aptian and the Cenomanian between the Albian and Turonian.<ref>{{Citation|last1=Ogg|first1=J.G.|title=Cretaceous|date=2012|url=https://linkinghub.elsevier.com/retrieve/pii/B9780444594259000275|work=The Geologic Time Scale|pages=793–853|publisher=Elsevier|language=en|doi=10.1016/b978-0-444-59425-9.00027-5|isbn=978-0-444-59425-9|access-date=2021-01-08|last2=Hinnov|first2=L.A.|last3=Huang|first3=C.}}</ref>