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

Geographers frequently go to the past for the answers to what environmental challenges our planet's warming globe will bring about in the future. The pyramids of Giza, one of the most famous man-made structures in the world, were made possible by the environment of ancient Egypt, according to a new study that was published on August 29 in Proceedings of the National Academy of Sciences. The authors of the study discovered that people need the waterway to move tools and other supplies like stones and limestones to the Giza Plateau for pyramid construction on a now-dry arm of the Nile River known as the Khufu branch. Sheisha Hader, a physical geographer at the University of Aix-Marseille in France and the study's principal author, adds that the Nile was an essential resource for ancient Egypt's transportation, food, land for farming, and water supplies.                                                                                                             

According to Hader, stable [Nile] levels "promised stability [to] the ancient Egyptian society." Contrarily, a severe drought brought on by low Nile levels would cause social discontent and occasionally civil warfare.

Hader and the crew examined pollen grains in May 2019 after drilling the area nearby the site of the former Khufu branch of the Nile. Two of the study locations were supposedly in the Khufu basin. For study, about 109 samples from the Predynastic to Early Dynastic-Old Kingdom eras were gathered and grouped into various groups based on seven vegetation patterns. The vegetation patterns, along with other data sets on solar radiation, historical African water levels, and nearby volcanic activity that may have caused weather changes, allowed the geographers to reconstruct past changes in water levels and create a picture of Egypt's climate over the past 8,000 years. The Khufu, Khafre, and Menkaure pyramids at Giza were thought to have been finished between 2686 and 2160 BCE, according to this timetable.

A stream near the Nile with some lush vegetation is depicted in color. A smaller pyramid is being built, and a larger one is in the backdrop.

Reconstruction by an artist of the long-gone Khufu branch of the Nile, which formerly allowed the delivery of building supplies to the Giza Pyramid complex. PNAS/Alex Boersma

Hader claims that she was more in awe of the "smart old kingdom's engineers who could thoroughly harness their environment and the Nile dynamics for making the impossible into reality" than she was shocked. She claims that the ancient Egyptians might have created a harbor on the edge of the desert using the river, where the tiny Khufu channel could drive in water without the threat of flooding. They dug the floodplain on the western side of the channel, allowed the water to flow, and let the ships navigate to feed the constructors logistically.

Before this study, how water got to the Giza pyramids was not fully understood, according to Joseph Manning, a professor of classics and history at Yale University. He says, "We'd heard there was water that reached very close to the Giza Plateau, which is how they're bringing stone from the Tura quarries [the Egyptians' primary supply of limestone] over the river over to Giza." "I assumed they were constructing connected canals, but it appears to be a natural river route," the speaker said.

Finding natural river features, according to Manning, provides context for how people interacted with and utilized their surroundings to build complex structures like the pyramids. He does raise some issues with the study's analysis of the information on volcanic eruptions that occurred at that time, though. According to their research, the Khufu branch oscillations that in this case reduced Nile summer flooding were largely caused by volcanic eruptions. The existence of a volcanic sequence alone does not necessarily indicate Nile conditions, he says. For instance, certain significant eruptions have been known to affect the East African monsoon, which can alter the water levels on the Nile, in high latitude places like Iceland or Alaska. However, not every eruption has an impact, according to Manning, who explains that other variables including the season, location, and size of the eruption will have an impact on how the Middle Eastern monsoon reacts.

The study extends beyond understanding the origin of these enormous monuments, according to senior study author and geomorphology specialist Christophe Morhange of the University of Aix-Marseille. The impact of humans on the environment and the significance of landscape archaeology are important factors.

According to Hader, fluctuations in the Nile were a key factor in the rise and fall of the ancient Egyptian empire. Climate scientists today can learn from studying a society that gained power by utilizing the local ecosystem in the past.

Hader says that it's critical to understand "the course of their history and how the environment could drive a flourishing empire like the former kingdom." But it's important to realize that environmental difficulties both now and in the future are related to climate change, which is the same cause for which the Roman Empire fell.