Abrupt return of the summer monsoon 15,000 years ago: new supporting evidence from the lower White Nile valley and Lake Albert

Stable-isotope (H, O, and Si) evidence for seasonal variations in hydrology and Si cycling from modern waters in the Nile Basin: implications for interpreting the Quaternary record

“…A large portion of the Nile Basin is underlain by Precambrian granitic and metamorphic rocks. Volcanic rocks are more extensively developed in Ethiopia than anywhere else along the East African Rift system (Williams et al, 2006;Schlüter, 2008). Although the Blue Nile Basin is underlain by Precambrian crystalline basement, over two-thirds of the Upper Blue Nile Basin is covered by a thick stack of weathered trap basalts (Kebede et al, 2005).…”

L’évolution hydromorphologique de la vallée du Yamé (Pays Dogon, Mali) : signal climatique et hydrosystème continental en Afrique de l’Ouest entre 50 et 4 ka cal. BP

“…Ils font donc état d'une situation très analogue à celle d'Oumounaama durant le stade isotopique 3 et lui confèrent ainsi vraisemblablement une signification régionale. Néanmoins, ces périodes d'aggradation en phase fluvio-palustre remaniant du matériel d'origine éolienne doivent être étudiées de manière plus approfondie si l'on veut pouvoir caractériser ce mode de fonctionnement (Heine et Heine, 2002 ;Williams et al, 2006).…”

River sediments

“…Two Late Pleistocene cores from Lake Albert contain palaeosols dated to 20.7-17.7 kyr ago and 16.6-15.1 kyr ago, indicating lake desiccation at those times, with a high lake level before 20.7 kyr ago and after 15.1 kyr ago evident in the 87 Sr/ 86 Sr values [89]. The older palaeosol coincides with the LGM.…”

“…To sum up, the Late Pleistocene Blue Nile and Atbara rivers were highly seasonal bed-load streams that, together with their tributaries, ferried and deposited vast quantities of poorly sorted sands and gravels in central Sudan and southern Egypt [77]. With the return of the summer monsoon towards 17 kyr ago, strengthening at 15 kyr ago [89], run-off increased in the Ethiopian headwaters, and Lake Tana overflowed once more [70]. From approximately 15 until 7.5 kyr ago and perhaps slightly later [61], the Holocene Blue Nile was depositing clays across the low-angle Gezira alluvial fan in the central Sudan.…”