A dried-up arm of the Nile provides another clue to how Egyptians built the pyramids

To understand what environmental issues lie ahead for our warming planet, geographers often look back to the past for answers. A new study published on August 29 in Proceedings of the National Academy of Sciences details how the landscape of ancient Egypt allowed them to create the pyramids of Giza—one of the most iconic human-made phenomenons in the world. On a now-dried-up arm of the Nile River called the Khufu branch, the study authors found that people needed the waterway to transport tools and other materials such as stones and limestones to the Giza Plateau for pyramid construction. The Nile was a vital resource not only for transportation, but for food, land for farming, and water for ancient Egypt, explains Sheisha Hader, a physical geographer at the Aix-Marseille University in France and lead author of the study.

“Good [Nile] levels promised stability [to] the ancient Egyptian society,” Hader says. “By contrast, the drought as a result of low Nile levels would be catastrophic and a reason for social unrest and sometimes, civil wars.”

In May 2019, Hader and the team studied pollen grains taken after drilling the land next to where the Khufu branch of the Nile once stood. Two of the study sites were in the supposed Khufu basin. About 109 samples dating between the Predynastic and Early Dynastic-Old Kingdom periods were collected for analysis and divided into different groups based on seven vegetation patterns. The vegetation patterns combined with other data sets involving nearby volcanic activity that could drive weather changes, solar radiation, and African water levels at the time, helped the geographers trace back changing water levels and painted a picture of how the climate looked over the last 8,000 years in Egypt. This timeline encapsulated the dates when the three pyramids of Giza—Khufu, Khafre, and Menkaure—were estimated to be completed, between 2686 and 2160 BCE.

Hader says she wasn't as much surprised but rather in awe of the “clever old kingdom's engineers who could thoroughly harness their environment and the Nile dynamics for turning the impossible into reality.” With the river, she says the ancient Egyptians were capable of designing a harbor on the edge of the desert where the small Khufu channel would drive in water without the risk of flood. “They dredged the floodplain on the western part of the channel and let the water flow, and the ships navigate to provide the logistic supply for builders.”


An artist's reconstruction of the now defunct Khufu branch of the Nile River, which once enabled transportation of construction materials to the Giza Pyramid complex.

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