Editing Vänern (section)

==History==
The southeastern part of the Vänern is a depression that appears to have been formed by erosion of [[Paleozoic]]-aged [[sedimentary rock]] during the [[Quaternary glaciation]].<ref name=HalletalVästgöt2019/> Such erosion would have re-exposed parts of the [[Sub-Cambrian peneplain]].<ref name=HalletalVästgöt2019>{{Cite report|title=The sub-Cambrian unconformity in Västergötland, Sweden: Reference surface for Pleistocene glacial erosion of basement|date=2019-12-01|url=https://www.skb.com/publication/2495096/TR-19-21.pdf|last=Hall|first=Adrian M.|access-date=2020-11-26|last2=Krabbendam|first2=Maarten|publisher=Swedish Nuclear Fuel and Waste Management Co|publication-date=2019-12-01|last3=van Boeckel|first3=Mikis|last4=Hättestrand|first4=Clas|last5=Ebert|first5=Karin|last6=Heyman|first6=Jakob}}</ref> Because the Sub-Cambrian peneplain gently tilts towards the north and west in this area, the southeast part of the lake is rather shallow.<ref name=HalletalVästgöt2019/> The western shore of the lake largely follows a [[fault scarp]] associated with the [[Vänern-Göta Fault]].<ref name=HalletalVästgöt2019/>

The lake reached its present form after the [[Quaternary glaciation]] about 10,000 years ago; when the ice melted, the entire [[Central Swedish lowland|width of Sweden]] was covered in water, creating a strait between [[Kattegat]] and the [[Gulf of Bothnia]]. When [[post-glacial rebound]] surpassed a concurrent sea-level rise, lake Vänern became a part of the [[Ancylus Lake]] that occupied the Baltic basin.<ref name=Bjork1995/> Vänern was connected to Ancylus Lake by a strait at [[Degerfors]], [[Värmland]]. Lakes such as Vänern and [[Vättern]] were cut off from the Baltic by further uplifting.<ref name=Bjork1995>{{cite journal |last1=Björck |first1=Svante |author-link=Svante Björck |date=1995 |title=A review of the history of the Baltic Sea, 13.0-8.0 ka BP |journal=[[Quaternary International]] |volume=17 |pages=19–40 |doi=10.1016/1040-6182(94)00057-C |bibcode=1995QuInt..27...19B }}</ref> As a result of this former connection to the sea, there are species here not normally encountered in freshwater lakes, such as the [[amphipoda|amphipod]] ''[[Monoporeia affinis]]''. A [[Viking ships|Viking ship]] was found at the bottom of the lake on May 6, 2009.<ref>{{Cite web|url=https://www.thelocal.se/20090508/19342|title='Viking ship' discovered in Sweden's largest lake|date=2009-05-08|website=www.thelocal.se|language=en-GB|access-date=2019-02-06}}</ref>

A story told by the 13th-century Icelandic mythographer [[Snorri Sturluson]] in his ''[[Prose Edda]]'' about the origin of [[Mälaren]] was probably originally about Vänern: the Swedish king [[Gylfi]] promised a woman, [[Gefjon]], as much land as four oxen could plough in a day and a night, but she used oxen from the land of the giants, and moreover uprooted the land and dragged it into the sea, where it became the island of [[Zealand]]. The ''Prose Edda'' says that 'the inlets in the lake correspond to the headlands in Zealand';<ref>Anthony Faulkes (ed. and trans), ''Snorri Sturluson: Edda'' (London: Everyman, 1987), p. 7.</ref> since this description is much more true of Vänern, the myth was probably originally about Vänern, not Mälaren.<ref>Heimir Pálsson, 'Tertium vero datur: A study of the text of DG 11 4to', p. 44 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-126249.</ref>

The [[Battle on the Ice of Lake Vänern]] was a 6th-century battle recorded in the Norse sagas and referred to in the Old English epic ''[[Beowulf]]''. In ''Beowulf'', Vänern is stated to be near the location of the dragon's mound at [[Earnaness]].<ref>Howell D. Chickering, Jr. (ed. and trans), ''Beowulf'' (New York: Anchor Books, 2006), lines 3030-3032.</ref>