How old is the Nile?
… It has been suggested that the Nile in its present path is ~6 million years old, whereas others argue that it may have formed much earlier in geological history. Here we present geological evidence and geodynamic model results that suggest that the Nile drainage has been stable for ~30 million years. We suggest that the Nile’s longevity in essentially the same path is sustained by the persistence of a stable topographic gradient, which in turn is controlled by deeper mantle processes. We propose that a large mantle convection cell beneath the Nile region has controlled topography over the last 30 million years, inducing uplift in the Ethiopian–Yemen Dome and subsidence in the Levant Sea and northern Egypt. We conclude that the drainage system of large rivers and their evolution over time can be sustained by a dynamic topographic gradient.
Apparently, an older Nile flowed through Libya, into the Sirte Rift (see image):
… we present geological and geophysical arguments supporting the idea that the Nile has been sustained by a mantle ‘conveyor belt’ operating through most of the Tertiary, with a convective upwelling centred under the Ethiopian highlands and a downwelling under the eastern Mediterranean, creating a topographic gradient that supported the Nile’s course over ~30 Myr. Such a course, which is similar to the present-day one, was likely established in the early Oligocene (∼30 Ma). Before that, our modelling shows that the drainage pattern was probably directed northwestward and controlled by the rifting process occurring in the Gulf of Sirte.
This indicates that at that time, rivers that drained into the Mediterranean Sea flowed farther to the west, possibly along the Sirte Rift that runs from northwest to southeast, which at that time was actively subsiding and being filled with a thick pile of sediments, indicating the activity of a large continental drainage…
Fascinating stuff. Read the whole paper here. (H/T Charles Onyango-Obbo)
As readers of the blog know, Nile waters are currently the subject of a diplomatic struggle between Ethiopia and Egypt. The US government recently offered to help negotiate a settlement. The parties involved set a January 15, 2020 deadline for negotiations. Stay tuned.
I didn’t even know about this. Amazing stuff!