For thousands of years, Nile has fertilized valleys along its winding road through northeastern Africa, rooted in ancient civilizations and still serves as an important route for transportation and irrigation today.
But the age of its valuable water, which extends over 6,200 miles (6,800 kilometers), has been discussed, with a group of experts claiming that the river was born about 6 million years ago when one drainage system changed course, while another claims that the river is five times older than that.
A new study finds evidence to support the latter theory: the Nile River may have arisen about 30 million years ago, driven by the Earth's mantle – the thick rock layer between the Earth's core and crust, a group of scientists reported today (November 11) in the journal nature Geoscience.
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The Nile River is believed to have formed at the same time as the Ethiopian highlands, says lead author Claudio Faccenna, professor at the Jackson School of Geosciences, University of Texas. The Ethiopian Highlands is where one of the great tributaries or branches of the Nile River, called the Blue Nile, begins.
The Blue Nile takes with it most of the Nile River's water – and most of the sediment in it – that goes with the river's second tide (the White Nile) in Sudan, before it empties into the Mediterranean.
Faccenna and his team had previously analyzed sediment collected from the Nile Delta – land created as sediment deposited where the river meets the Mediterranean – and compared their composition and age to ancient volcanic rock found on the Ethiopian Plateau. They found that sediments and rocks matched and were between 20 million and 30 million years old, indicating that the river formed at the same time as the plateau.
So then the researchers were interested to see how the river might have been connected to the Earth's mantle, as the theory suggested, Faccenna told Live Science. In the new study, Faccenna and colleagues created a computer simulation that recreated 40 million years of Earth's flat tectonics – a theory that suggests the outer shell of the earth is cut into pieces that move and slide over the mantle.
Their simulation showed that a hot mantle plum – a rise of extremely hot mountains in the mantle – pushed the ground upwards, created the Ethiopian highlands and also activated a still existing mantle "conveyor belt" that shoots upwards on the Ethiopian highlands in the south and pulls the ground down in the north. . This creates a slope north, on which the Nile is still running, Faccenna said.
It is unclear whether the Nile River has ever changed course throughout its life – if anything – and it is something that Faccenna and his team hope to come up with in the future. They also want to implement this method to analyze how the mantle may also have changed course for other rivers around the world.
Originally published it Live science.