Without a now-gone Nile River tributary, the Pyramids of Giza would not have been possible

The seventh wonder of the world, Cheops' pyramid, is one of the Giza pyramids, which captures the imagination. Not least of all due to the fact that they are built with millions of leaden stones. Naturally, you then ponder how the ancient Egyptians managed to get those stones there.

Tributary of the Nile River

Now, a group of researchers from several countries believes they can clarify that. They contend in the PNAS journal that a now-extinct Nile tributary must have played a significant influence. The distance between the Giza pyramids and the Nile today is a few kilometers. The researchers demonstrate that conditions were different at the time these structures emerged.

The research

It is not novel to think that the ancient Egyptians transported their building supplies, as well as likely food for the workmen, to Giza using a now-defunct canal. However, little is known about precisely when that tributary started, how long it persisted, and how much water it held, the researchers write in the journal Proceedings of the National Academy of Sciences. It was therefore unclear how much it had truly contributed to the development of the Seventh Wonder of the World and the area around it.

To change that, scientists have now developed a reconstruction of how this now-extinct tributary fared over the past several thousand years using fossilized pollen. And the findings suggests that the tributary, which experts refer to as the Cheops Branch, must have held a significant amount of water when the Giza pyramids were constructed. According to researcher Hader Sheisha, "the water level in the Cheops branch was largely stable during the first half of the Old Kingdom of Egypt (2686 to 2440 BC)." To be more precise, the water level was 40% lower then than it was during the so-called African Humid Period, a time when northern Africa experienced significantly higher rainfall than it does now and the Sahara even had grasses, trees, and lakes. The tributary must have reached the Giza plateau and the water level must have been high enough that boats carrying heavy loads could easily reach that plateau, even if the Cheops branch did contain significantly less water at the time the pyramids were built than during that wet period. "The Cheops branch, which reigned from the third to the fifth dynasties, undoubtedly contributed to the birth and growth of a pyramid building site. Construction personnel were assisted in organizing the boat shipment of stones and other materials by the Cheops branch."

Fossilized pollen

As previously stated, the scientists infer that from fossilized pollen. What vegetation was present in the area is then revealed by these pollen. Additionally, the vegetation itself provides information about the localized level of moisture. "For instance, wet conditions are correlated with the more frequent occurrence of cyber grass family plants (such as the papyrus reed, which we are familiar with from the banks of the Nile). Additionally, there is pollen from plants whose natural habitat is higher upstream, and whose pollen is transported downstream by the river. Or helophytes, like cattail, which indicate the presence of a permanent body of water close to Giza." Land plants, such as particular herbs, cereals, or ferns, may also signal drier weather. "And thus to the Cheops tributary's simple stagnation."

Reconstructing the ancient past

And because of that pollen, experts can now estimate not only when the Cheops tributary had water, but also, for instance, how high it must have been. Finally, it offers a recreation of a flow region that dates back thousands of years. As a result, the reconstruction shows that the water in the now-gone side branch was running freely when the Giza pyramids were being constructed. And it, according to Sheisha, was essential to the building of the Giza pyramids. To transport the 2 million blocks of granite and limestone required to erect the pyramids to their final location, for instance, the tributary must have been useful.

The villain: climate change

Even though the side branch was significant, it finally vanished. Sheisha says, "I think it's quite obvious that the side branch was a natural phenomena, developed during the African Humid Period. Due to the extreme wetness of the time, the Nile developed numerous side branches, of which the Cheops branch continued long after the period of extreme wetness had ended, albeit with a little reduced water level. But the tributary must have succumbed to drought somewhere between 1500 and 1100 BC. Sheisha says that the drought has also been connected to a volcanic eruption. As sulfur gases were injected into the stratosphere, solar energy was reflected back into space, resulting in a decrease in tropospheric temperatures and a change in precipitation patterns. As a result, a dry period may have also started in Egypt, which was devastating for the Nile tributary.

However, the Giza pyramids had been towering tall for roughly 1,000 to 1,500 years when the tributary vanished. Thus, they continue to stand as a testament not only to the concepts and related inventiveness of the ancient Egyptians, but also to a lost and disappeared canal that was undoubtedly essential to their revival. It is really beneficial to know that the tributary existed and undoubtedly contributed to the creation of the pyramids, claims Sheisha. "A greater understanding of the environment (of the pyramids, ed.) changes our perspective on the building of these huge pyramids and helps us better understand a lot of decisions," according to the author.