Editing Tethys Ocean (section)

==Historical theory==

In Chapter 13 of his 1845 book,<ref>{{cite book |last1=Murchison |first1=Roderick Impey|last2=de Verneuil |first2=P. E.|last3=von Keyserling |first3=A.|title=On the Geology of Russia in Europe and the Ural Mountains|url= https://archive.org/details/bub_gb_He1P7aF0nCYC/page/296/mode/2up |year=1845|publisher=John Murray|location = London|volume = 1|pages = 297–323|display-authors=0}}</ref> [[Roderick Murchison]] described a distinctive formation extending from the [[Black Sea]] to the [[Aral Sea]] in which the creatures differed from those of the purely marine period that preceded them. The [[Miocene]] deposits of [[Crimea]] and Taman (south of the [[Sea of Azov]]) are identical with formations surrounding the present [[Caspian Sea]], in which the [[univalve]]s of freshwater origin are associated with forms of Cardiacae and Mytili that are common to partially saline or brackish waters. This distinctive fauna has been found throughout all the enormously developed Tertiary formations of the southern and south-eastern steppes.

{{Blockquote
|text=... and leads at once to the conviction, that during long periods antecedent, as will be hereafter explained, to the historic æra, a vast region of Europe and Asia was covered by a Mediterranean Sea of brackish water, of which the present Caspian is the diminished type. ... To render the distinction between these accumulations and all others clear and unambiguous, we have adopted the term Aralo-Caspian, first applied in a geographical sense, by our great precursor Humboldt, to this region of the globe. ... Judging from the recital of travellers and from specimens of the rock, we have no doubt that it extended to Khivah and the Aral Sea ; beyond which the low level of the adjacent eastern deserts would lead us to infer, that it spread over wide tracts in Asia now inhabited by the [[Turkmens|Turkoman]]s and [[Kyrgyz people|Kirghis]], and was bounded only by the mountains of the [[Hindu Kush|Hindoo Kusk]] and [[Chinese Tartary]]. ... there can be no sort of doubt, that all the masses of water now separated from each other, from the Aral to the Black Sea inclusive, were formerly united in this vast pre-historical Mediterranean ; which (even if we restrict its limits to the boundaries we already know, and do not extend them eastward, amid low regions untrodden by geologists) must have exceeded in size the present Mediterranean!}}

On the accompanying map, Murchison shows the Aralo-Caspian Formation extending from close to the Danube delta across Crimea, up the east side of the [[Volga river]] to Samara, then south of the Urals to beyond the Aral Sea. Brackish and upper freshwater components (OSM) of the Miocene are now known to extend through the [[Molasse basin|North Alpine foreland basin]] and onto the [[Swabian Jura]] with thickness of up to {{Convert|250|m|abbr=on}}; these were deposited in the [[Paratethys]] when the Alpine front was still {{cvt|100|km}} farther south.<ref>{{cite journal 
 |last1=Steininger |first1=F. F.
 |last2=Wessely|first2=G.
 |title= From the Tethyan Ocean to the Paratethys Sea: Oligocene to Neogene stratigraphy, paleogeography and paleobiogeography of the circum-Mediterranean region and the Oligocene to Neogene Basin evolution in Austria
 |year = 2000|journal=Mitteilungen der Österreichischen Geologischen Gesellschaft |volume=92|pages=95–116}}</ref><ref>{{cite journal 
 |last1=Kuhlemann |first1=J.
 |last2=Kempf|first2=O.
 |title=Post-Eocene evolution of the North Alpine Foreland Basin and its response to Alpine tectonics|year = 2002 |journal=Sedimentary Geology |volume=152|issue=1–2
 |pages=45–78|doi=10.1016/S0037-0738(01)00285-8
 |bibcode=2002SedG..152...45K
 }} </ref>

[[File:Eduard Suess 1869.jpg|thumb|upright|Geologist [[Eduard Suess]] in 1869]]
In 1885, the Austrian palaeontologist [[Melchior Neumayr]] deduced the existence of the Tethys Ocean from Mesozoic marine sediments and their distribution, calling his concept {{lang|de|Zentrales Mittelmeer}} ({{literal translation|Central Mediterranean Sea}}) and described it as a Jurassic seaway, which extended from the Caribbean to the Himalayas.<ref>{{Harvnb|Kollmann|1992}}</ref>

In 1893, the Austrian geologist [[Eduard Suess]] proposed the hypothesis that an ancient and extinct [[Inland sea (geology)|inland sea]] had once existed between Laurasia and the continents which formed [[Gondwana]] II. He named it the Tethys Sea after the Greek sea goddess Tethys. He provided evidence for his theory using fossil records from the Alps and Africa.<ref>{{Harvnb|Suess|1893|p=183}}: "This ocean we designate by the name 'Tethys' after the sister and consort of Oceanus. The latest successor of the Tethyan Sea is the present Mediterranean."</ref> He proposed the concept of ''Tethys'' in his four-volume work {{lang|de|Das Antlitz der Erde}} (''The Face of the Earth'').<ref>{{Harvnb|Suess|1901|loc=Gondwana-Land und Tethys, p. 25}}: {{lang|de|"Dasselbe wurde von Neumayr das 'centrale Mittelmeer' genannt und wird hier mit dem Namen Tethys bezeichnet werden. Das heutige europäische Mittelmeer ist ein Rest der Tethys."}} ("It was named by Neumayr the 'central Mediterranean [literally: Middle] Sea' and here it will be designated by the name 'Tethys'. The current European Mediterranean Sea is a remnant of the Tethys.")</ref>

In the following decades during the 20th century, "[[Continental drift|mobilist]]" geologists such as Uhlig (1911), Diener (1925), and Daque (1926) regarded Tethys as a large trough between two [[supercontinent]]s which lasted from the late Palaeozoic until continental fragments derived from Gondwana obliterated it.

After [[World War II|World War&nbsp;II]], Tethys was described as a triangular ocean with a wide eastern end.{{citation needed|date=June 2017}}

From 1920s to the 1960s, "fixist" geologists, however, regarded Tethys as a composite trough, which evolved through a series of [[orogenic]] cycles. They used the terms 'Paleotethys', 'Mesotethys', and 'Neotethys' for the [[Caledonian orogeny|Caledonian]], [[Variscan orogeny|Variscan]], and Alpine orogenies, respectively. In the 1970s and 1980s, these terms and 'Proto-Tethys', were used in different senses by various authors, but the concept of a single ocean wedging into Pangea from the east, roughly where Suess first proposed it, remained.<ref>{{Harvnb|Metcalfe|1999|loc="How many Tethys Oceans?", pp. 1–3}}</ref>

In the 1960s, the theory of [[plate tectonics]] became established, and Suess's "sea" could clearly be seen to have been an ocean. Plate tectonics provided an explanation for the mechanism by which the former ocean disappeared: [[oceanic crust]] can [[subduction|subduct]] under [[continental crust]].{{citation needed|date=June 2017}}

Tethys was considered an oceanic plate by Smith (1971); Dewey, Pitman, Ryan and Bonnin (1973); Laubscher and Bernoulli (1973); and Bijou-Duval, Dercourt and Pichon (1977).{{cn|date=July 2022}}