Editing Lake Zaysan (section)

==Geography==
The lake lies at an altitude of {{convert|420|m|abbr=on}}, in a hollow between the [[Altai Mountains|Altai]] and the [[Tarbagatai Mountains]]. It is {{convert|105|km|abbr=on}} long with an approximate width of between {{convert|22|and|48|km|abbr=on}}. The major river flowing into it is the ''[[Kara Irtysh]]'' (Black Irtysh) and ''Kendyrlyk'' from the east; its only outlet is the ''[[Irtysh River|Ertis]]'', or Irtysh River.

Since the construction of the [[Bukhtarma Hydroelectric Power Plant|Bukhtarma Dam]] on the Irtysh, downstream from the Zaysan, the lake has risen around {{convert|6|m|ft|abbr=on}} above its natural level. As a result, the area of the lake has (essentially) doubled, from about 1,800&nbsp;km<sup>2</sup> to 3,500&nbsp;km<sup>2</sup><ref>''Soviet Encyclopedic Dictionary, Moscow'', 1980, p. 451.</ref> (or even to 5,000&nbsp;km<sup>2</sup>);<ref>{{Cite web|url=http://www.britannica.com/EBchecked/topic/656085/Lake-Zaysan|title=Lake Zaysan &#124; lake, Kazakhstan &#124; Britannica}}</ref> thus, in some sources, the lake is indicated as part of an artificial reservoir.<ref>''Soviet Encyclopedic Dictionary, Moscow'', 1980, p. 451.</ref> Man-made reservoirs are abundant over a large portion of the surrounding area.

[[Lake Baikal]] is often considered the most [[ancient lake]] in the world, as clear evidence shows that it is 25–30 million years old.<ref>{{cite web|url=https://whc.unesco.org/en/list/754|title=Lake Baikal – UNESCO World Heritage Centre|access-date=8 March 2018}}</ref><ref>{{cite web|url=https://www.sciencedaily.com/releases/2017/07/170726103013.htm|title=Lake Baikal: Protection of a unique ecosystem|website=ScienceDaily|date=26 July 2017|access-date=8 March 2018}}</ref> Lake Zaysan, however, may be even older, dating possibly from the [[Cretaceous]] period, with a potential age in excess of 66 million years old<ref name=Lucas2012>{{cite journal| author1=Lucas| author2=Bray| author3=Emry| author4=Hirsch |year=2012 | title=Dinosaur eggshell and Cretaceous-Paleogene Boundary in the Zaysan Basin, eastern Kazakstan | journal=Journal of Stratigraphy | volume=36 | issue=2 | pages=1376–1382 | doi=10.1016/j.proenv.2011.09.220 | doi-access=free }}</ref> (most probably around 70 million years<ref name=Dorfman2011>{{cite journal| author=Dorfman, B.F.|year=2011 | title=Zaysan-the Only Surviving Cretaceous Lake-May be Lost | journal=Procedia Environmental Sciences | volume=10 | issue=B | pages=1376–1382 | doi=10.1016/j.proenv.2011.09.220 | doi-access=free }}</ref>); the exact age is debatable, and surrounded with some uncertainty.<ref name=WorldAtlasOldestLakes>{{cite web | url=https://www.worldatlas.com/articles/the-oldest-lakes-in-the-world.html |title=The Oldest Lakes in the World |date=25 August 2017 | publisher=World Atlas |access-date=8 March 2018 }}</ref> A clear indication of Lake Zaysan's age has proven hard to find, although some geological studies of the Zaysan Basin have been undertaken.<ref>''AAPG Studies in Geology #46'', (2000). Chapter 29</ref> Modern geological analysis of the entire field, apparently, supports an exceptionally old age for Lake Zaysan.<ref>L. E. Popov et al (2009)</ref><ref>Kröner et al</ref>