Editing Lake Victoria (section)

==Geology==
{{Refimprove science | section | date = December 2024}}
[[File:Topography of Lake Victoria.png|thumb|Topographical map of Lake Victoria]]
Photojournalist [[John Reader]], writing in his Alan Paton Literary Award-winning ''Africa: A Biography of a Continent'',<ref>{{cite news | author = The Times Staff | date= 26 February 2009  | orig-date= 4 June 2007  | title = Previous Winners of the Alan Paton Award and the Sunday Times Fiction Prize | newspaper = The Times (Johannesburg) | url = http://www.thetimes.co.za/SpecialReports/BookAwards/Article.aspx?id=482608 | access-date = 26 December 2024 | archive-url = https://web.archive.org/web/20090226215141/http://www.thetimes.co.za/SpecialReports/BookAwards/Article.aspx?id=482608 | archive-date = 2009-02-26 | url-status = dead | quote = Previous Literary Awards winners / Previous Winners of the Alan Paton Award / 1998: Africa: A Biography of a Continent by John Reader, published by Penguin SA }}</ref> describes Lake Victoria as being relatively geologically young at about 400,000-years old—having been formed as westward-flowing rivers were backed up "when a fractured block of the Earth's crust tilted along the line of the Great Rift Valley, raising its western edge".<ref name="Reader">{{cite book | author = Reader, John | date = 2001 | orig-date = 1998 | title=Africa: A Biography of a Continent | location=Washington, DC | publisher=[[National Geographic Society]] | via = Archive.org | isbn=9780792276814 | pages=227f | url-access=registration | url=https://archive.org/details/africa0000read | access-date = 26 December 2024}}</ref>{{better source|date = December 2024}}<!--THIS IS A POPULAR WORK, AND NOT A SCHOLARLY GEOLOGICAL SOURCE.--> A primary study, attempting "fluvial differentiation of the basin of Lake Victoria", draws several relevant tentative conclusions. First, during the [[Miocene]] era, what is now the catchment area of the lake was on the western side of an uplifted area that functioned as a continental divide, with streams on the western side flowing into the [[Congo River]] basin and streams on the eastern side flowing to the Indian Ocean. Second, as the [[East African Rift]] System formed, the eastern wall of the [[Albertine Rift]] (or Western Rift) rose, gradually reversing the drainage towards what is now Lake Victoria. Third, the opening of the main East African Rift and the Albertine Rift downwarped the area between them as the rift walls rose, creating the current Lake Victoria [[Structural basin|basin]].<ref>{{Cite journal |last=Ouma |first=J. P. B. M. |date=1970 |title=Fluvial Differentiation in the Basin of Lake Victoria |url=https://www.jstor.org/stable/43944206 |journal=Journal of Hydrology (New Zealand) |volume=9 |issue=2 |pages=221–223 |jstor=43944206 | quote = On the basis each of catchment texture, catchment shape, and stream length propagation ratio, fluvial differentiation of the basin of Lake Victoria is attempted.}}{{primary source inline|date = December 2024}}</ref>{{primary source inline|date = December 2024}} 

During its geological history, Lake Victoria went through changes ranging from its present shallow depression, through to what may have been a series of much smaller lakes.<ref name="Hickling61"/>{{page needed|date = December 2024}}{{update after|2024|12|27}} [[core sample|Geological cores]] taken from its bottom show Lake Victoria has dried up completely at least three times since it formed.<ref name="Reader"/>{{better source|date = December 2024}} These drying cycles are probably related to [[Quaternary glaciation|past ice ages]], which were times when [[precipitation (meteorology)|precipitation]] declined globally.<ref name="Reader"/>{{better source|date = December 2024}} According to another primary source, Lake Victoria last dried out about 17,300 years ago, and it refilled 14,700 years ago<ref name="Verheyen2003">{{cite journal |author=Verheyen, Erik; Salzburger, Walter; Snoeks, Jos & Meyer, Axel |year=2003 |title=Origin of the Superflock of Cichlid Fishes from Lake Victoria, East Africa |journal=[[Science (journal)|Science]] |volume=300 |issue=5617 |pages=325–329 |doi=10.1126/science.1080699 |pmid=12649486 |bibcode=2003Sci...300..325V |s2cid=84478005 |url=http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-32706 |doi-access=free }}</ref>{{primary source inline|date = December 2024}}—as the [[African humid period]] began.<ref>{{cite journal |last1=deMenocal |first1=Peter |last2=Ortiz |first2=Joseph |last3=Guilderson |first3=Tom |last4=Adkins |first4=Jess |last5=Sarnthein |first5=Michael |last6=Baker |first6=Linda |last7=Yarusinsky |first7=Martha |title=Abrupt Onset and Termination of the African Humid Period |journal=Quaternary Science Reviews |date=January 2000 |volume=19 |issue=1–5 |pages=347–361 |doi=10.1016/S0277-3791(99)00081-5  |language=en |issn=0277-3791 |bibcode=2000QSRv...19..347D}}</ref>