By Zoe Sottile, CNN
New evidence on the Nile bolsters a long-held theory of how the ancient Egyptians managed to build the massive pyramids of Giza thousands of years ago.
Researchers led by geographer Hader Sheisha from the University of Aix-Marseille in France have used paleoecological clues to reconstruct what the Egyptian Nile might have looked like over the past 8,000 years.
They determined that the pyramid builders likely took advantage of a “now extinct” arm of the river to move building materials, according to a study published Aug. 24 in the Proceedings of the National Academy of Sciences.
Their findings show “that ancient waterscapes and higher river levels around 4,500 years ago facilitated the construction of the Giza pyramid complex,” according to the study.
The Great Pyramid is approximately 455 feet tall and was commissioned by Pharaoh Khufu in the 26th century BC. Made up of 2.3 million blocks of stone with a combined mass of 5.75 million tons (16 times more than the Empire State Building), it is the largest of the Giza group of pyramids. The other two main pyramids belong to Khufu’s son Khafre and grandson Menkaure.
Built on the Giza Plateau bordering Cairo, the structures – surrounded by temples, cemeteries and working class quarters – are the oldest of the Seven Wonders of the Ancient World.
Ancient engineers used floods as hydraulic lifts
Scientists have long speculated that the ancient Egyptians must have mined ancient parts of the Nile to move the tons of limestone and granite needed to build the giant structures. (Present Nile rivers have traveled too far from the sites of the pyramids to be useful.)
This explanation, known as the “river port complex” hypothesis, posits that ancient Egyptian engineers dug a small channel across from the site of the pyramid to the Khufu branch of the Nile, along the western edge from the floodplain of the river, and have dredged basins to the bottom of the river. The annual floodwaters functioned as a hydraulic lift, allowing them to move huge blocks of stone to the construction site, the researchers said.
But until now, scientists didn’t have a precise understanding of the landscapes involved, the researchers said.
Using a combination of techniques to reconstruct the ancient floodplain of the Nile, the research team found that Egyptian engineers could have used the now-dried Khufu branch of the Nile to move building materials to the site of the Giza pyramids. .
First, they analyzed rock layers from cores drilled in 2019 in the Giza floodplain to estimate water levels in the Khufu Branch thousands of years ago. They also examined fossilized pollen grains from clay deposits in the Khufu region to identify areas rich in vegetation that indicate high water levels.
Their data showed that the Khufu region flourished during the first half of Egypt’s Old Kingdom period, from about 2700 to 2200 BC, when the construction of the three main pyramids probably took place.
The branch still had high water levels during the reigns of Pharaohs Khufu, Khafre and Menkaure.
“From the Third Dynasty to the Fifth Dynasty, the Khufu branch clearly provided a conducive environment for the emergence and development of the pyramid construction site, helping builders plan the transportation of stone and materials by ship,” notes the research team in the study.
But at the end of Egypt, from about 525 to 332 BC. BC, water levels in the Khufu branch had dropped during a dry phase – a finding that is consistent with studies of oxygen in the teeth and bones of mummies from the period that reflect a low water consumption. , according to the study.
When Alexander the Great conquered Egypt in 332 BC. BC, the Khufu branch was only a small channel.
Altogether, the data shows that these ancient engineers used the Nile and its annual floods “to exploit the plateau area overlooking the floodplain for monumental building.” In other words, the ancient Khufu branch of the Nile was indeed high enough to allow ancient engineers to move huge blocks of stone – and build the magnificent pyramids we know today.
Paleoclimatology affects our understanding of the past and the future
For Joseph Manning, a classicist historian at Yale University, the “groundbreaking” research is an example of how paleoclimatology is “fundamentally changing our understanding of human history.”
“We’re getting a more realistic and dynamic understanding of human societies farther back in time,” he told CNN.
These new techniques — like the pollen analysis used in this study — allow scientists to peer into societies thousands of years ago, Manning said.
“Climate science, as in this article, gives us fundamentally new information… (that is,) very relevant to what is happening today.” Understanding how the climate changed during the Old Kingdom of ancient Egypt, for example, gives scientists context for current trends in climate change.
Previously, historians of ancient Egypt relied primarily on texts to derive their understanding of Egyptian society, Manning said. But increasingly, environmental science is “throwing everything out the door” and enabling new insights into the ancient world.
The most novel part of the new research is that it identifies a natural waterway that could have been used to transport pyramid materials, something some researchers previously thought an artificial channel must have been necessary for, Manning said.
To get the most out of environmental history, scientists will need to collaborate and work with historians, he said. “There’s resistance, because it’s a different way of working,” Manning said.
But the possibilities, he added, are “super exciting”.
The-CNN-Wire
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