The ancient Egyptians considered the river to be the source of all life. Its constant path to the north has fed the fertile valleys of northeastern Africa and, in doing so, shaped the course of human civilization.
However, the exact age of its venerable waters, which span 6,800 kilometers, has been the subject of debate. A group of scientists has suggested that the Nile, on its current route, is about 6 million years old. Others disagree, they argue that it could have been formed much earlier and be up to five times older.
Now a new study published in Nature Geoscience has found evidence that supports the latest theory: its origin dates back to 30 million years ago, driven by the movement of the earth’s mantle, the layer immediately below the earth’s crust.
“It is thought that the Nile River formed at the same time as the highlands of Ethiopia,” explains lead author Claudio Faccenna, a professor at the Jackson School of Geosciences at the University of Texas. “These Ethiopian lands are where one of the largest branches and tributaries of the main river, called the Blue Nile, begins.”
The Blue Nile brings most of the water from the Nile – and most of the sediments in it -, joining with another tributary, the White Nile, in Sudan, before reaching the Mediterranean Sea.
Faccenna and his team have previously analyzed the sediments collected in the Nile Delta – land created as sediments settle where the river meets the sea – and compared their composition and age with ancient volcanic stones found in the Ethiopian highlands. Thus they discovered that the sediments and rocks coincided and dated between 20 and 30 million years, suggesting that the river was born at the same time as the high plateau.
Using that knowledge as a basis and taking into account other geological data, the researchers created a computational simulation that reproduced 40 million years of history of tectonic plates in that area. In this way the new technology allowed them to confirm the theory: a warm tuft of the mantle pushed the geography upwards, creating the highlands of Ethiopia in the south and activating, at the same time, a “conveyor belt” that also sinks the ground in the North.
“This creates a steep slope to the north, over which the Nile still flows,” says Faccenna.
It is still unclear if the Nile River ever changed its course – even slightly – and that is something this team of scientists hopes to find out in the future. They also want to implement the same method to analyze how the mantle may have changed the course of other rivers around the world.
Source: Live Science.