Geomorphologists have confirmed, for the first time, the route of a long-extinct ‘branch’ of the Nile River that brought the famous river to the base of its equally renowned pyramids.
Today, Egypt’s pyramids are surrounded by sand and situated kilometres from the river’s banks, but it would have been a very different story when they were first built thousands of years ago.
Past investigations had found evidence suggesting a branch of the Nile likely swept past the pyramids, but through the use of radar, soil excavations, geophysical surveys and historic maps, a team of researchers led by Egyptian-American geomorphologist Eman Ghoneim from the University of North Carolina Wilmington have connected the dots to confirm a likely route.
The result is a map of a winding offshoot of the Nile running along the western banks of the modern river published today in the journal Communications Earth & Environment.
Dubbed the ‘Ahramat Branch’, this 64km waterway would have run to the foot of Egypt’s iconic pyramids, including the famous monuments at Giza, and a chain of lesser-known structures at Abusir, Saqqara, Dahshur and Lisht.
In modern times, these pyramids sit inside an inhospitable part of the Sahara known as the Western Desert. But the analysis performed by Ghoneim’s team of geomorphologists and archaeologists supports long-held views among researchers that this strip of land 4-6km west of the modern Nile banks would have been fertile, and aquatic.
“Mostly people have not been able to map out or identify where those waterways were,” says Tim Ralph, a geomorphologist from Macquarie University who was the second author of the research.
“There’s a common acceptance that the pyramids must have been near a waterway because they’ve got these [boat] docks, but for the first time we’ve created a map and checked on the ground that this was actually the case.”
Core History
Ralph and his colleagues decoded the process that forced the Nile landscape to change over the past 5,000 years using several techniques to extract and analyse the centuries of sediment deposits that took the region from riverbed to farmland.
Soil coring was fundamental to the on-the-ground analysis. Using handheld ‘augers’ that allow small tubes of earth to be extracted, they studied 15cm chunks of sediment layers at a time.
They also commissioned Egyptian workers to extract larger sediment cores for analysis.
Once removed, cores are described and recorded in sequence. This includes detailed reports of layer composition – whether it’s a ‘clean’, sandy layer suggestive of an energetic river washing over the top, or silty and muddy, which might indicate a river is no longer close by.
“We know the fundamental physics of particles and their movement is that the larger, heavier particles in a river require more energy to move them and transport them,” says Ralph.
“So if the river ‘moves’ further away from where we’ve dug our hole, we tend to find finer sediment at the site that we’re digging because the energy in the river is focused elsewhere… whereas if we find these very coarse, sandy layers, we know the river was either right there or very close to there, to be able to deposit that sand there.
“By drilling lots of holes by surveying the topography, we can start to pick out the stratigraphy – the different layers across the floodplain – and then look for these old channel beds.”
These observations were combined with ground-penetrating radar and tomography performed by the Egyptian National Institute to indicate the composition of soil below the surface.
Pairing these scans with the core records enabled Ghoneim, Ralph and the rest of the group to trace the probable path of the Ahramat Branch.
A piece to the pyramid puzzle
Whether the Ahramat Branch was part of the main Nile or a branch feeding into the larger river remains unclear, but confirming the likely course this channel took around 4,700 years ago can help other scientific research disciplines.
Now, historians can confidently explain how ancient Egyptians would have been able to move large pyramid stones such long distances, as their construction sites were snuggled up against the banks of a vital transport corridor.
It also gives an ‘X’ for archaeologists to focus future studies, with the knowledge of where an extensive river once flowed.
“A lot of old historical accounts of temples and settlements along the Nile refer to the river,” Ralph says.
“Of course those people 2,000 years ago when they were writing about the temple or monument and describing where it sat on the river, in most cases probably weren’t where the river exists today.
“If the river has moved… archaeologists who are looking for these places may be looking in a different place. What we hope our work will eventually guide is future sites of cultural significance conservation efforts.
“It might help people find other sites and help the Egyptian Government and people secure those for the future before they’re lost to time.”
