There are two theories about the age of the integrated Nile. One is that the integrated drainage of the Nile is of young age, and that the Nile basin was formerly broken into series of separate basins, only the most northerly of which fed a river following the present course of the Nile in Egypt and Sudan. Said postulated that Egypt itself supplied most of the waters of the Nile during the early part of its history.
The other theory is that the drainage from Ethiopia via rivers equivalent to the Blue Nile and the Atbara and Takazze flowed to the Mediterranean via the Egyptian Nile since well back into Tertiary times.
Salama suggested that during the Tertiary (65 million to 2.588 million years ago) a series of separate closed continental basins each occupied one of the major parts of the Sudanese Rift System: Mellut rift, White Nile rift, Blue Nile rift, Atbara rift and Sag El Naam rift. The Mellut Rift Basin is nearly 12 kilometers (7 mi) deep at its central part. This rift is possibly still active, with reported tectonic activity in its northern and southern boundaries. The Sudd swamps which form the central part of the basin may still be subsiding. The White Nile Rift System, although shallower than the Bahr el Arab rift, is about 9 kilometers (6 mi) deep. Geophysical exploration of the Blue Nile Rift System estimated the depth of the sediments to be 5–9 kilometres (3.1–5.6 mi). These basins were not interconnected until their subsidence ceased, and the rate of sediment deposition was enough to fill and connect them. The Egyptian Nile connected to the Sudanese Nile, which captures the Ethiopian and Equatorial headwaters during the current stages of tectonic activity in the Eastern, Central and Sudanese Rift Systems. The connection of the different Niles occurred during cyclic wet periods. The River Atbara overflowed its closed basin during the wet periods that occurred about 100,000 to 120,000 years ago. The Blue Nile connected to the main Nile during the 70,000–80,000 years B.P. wet period. The White Nile system in Bahr El Arab and White Nile Rifts remained a closed lake until the connection of the Victoria Nile to the main system some 12,500 years ago.
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