Engineers look at structures associated with the pyramid Pharaoh Djoser built 4,700 years ago and realize: That's a hydraulic system
An aerial view of Djoser's complex and stepped pyramid in SaqqaraCredit: Yann Arthus Bertrand
One of the most debated and enduring mysteries about the pyramids centers on how they were built.
How did the ancient Egyptians raise millions of massive limestone blocks to great heights to erect these funerary monuments that have stood for nearly five millennia?
For a while now, researchers have been convinced that Egyptian workers (mind you, they were skilled laborers, not slaves) used a combination of ramps, sledges, ropes and levers to build the pyramids. But a study of the oldest pyramid in Egypt, this time not by archaeologists but engineers, now says that, at least in this case, ancient architects had one additional trick up their sleeve: getting water to do the heavy lifting.
Djoser statue, at the Egyptian MuseumCredit: Jon Bodsworth, Wikimedia Commons
The analysis of the stepped pyramid built by Pharaoh Djoser from around 2680 B.C.E., the first pyramid known to have been built in Egypt, claims to have revealed a complex water management system that included a hydraulic lift at the heart of the monument. This would have allowed limestone blocks to be raised from the center of the pyramid, constructing the monument in a 'volcano' style, the new study says.
The research was conducted by a team of French engineers, hydrologists and other experts using a combination of satellite radar images and more than a century's worth of reports by archaeologists. The study, published Wednesday as a pre-print on ResearchGate, claims to have uncovered a whole new method the Egyptians may have used to build their pyramids and highlights how advanced this ancient civilization's technical knowhow was.
The team analyzed multiple features within and around Djoser's pyramid whose precise function had so far eluded archaeologists, and found them to be textbook water management structures, says Dr. Xavier Landreau, an engineer and material scientist who led the study.
Djoser was a pharaoh in the Third Dynasty of Egypt's Old Kingdom. The stepped pyramid is the crowning jewel of his funerary complex, which includes additional temples and buildings surrounded by a dry moat. It rises to a height of 60 meters and is located in the Saqqara Plateau, some 6 kilometers west of the Nile and 15 kilometers south of Giza, where, starting about a century later, the Fourth Dynasty pharaohs would build their own, even grander, pyramids.
The French team focused on Djoser's complex, rather than on the more famous Giza Pyramids, because they wanted to be able to trace the evolution of ancient Egypt's construction techniques, Landreau says. So, they started from the beginning.
The Djoser step pyramid at SaqqaraCredit: Olaf Tausch
Damnit, it's a dam!
The first discovery concerned the Gisr el-Mudir, an enigmatic rectangular stone enclosure almost two kilometers long that lies immediately west of Djoser's complex.
The enclosure, which is believed to predate Djoser's pyramid and is considered one of the world's oldest stone structures, has been variably interpreted as a cattle pen, fortress or sacred space.
None of that is correct, says Landreau, who heads Paleotechnic, a private lab that bring together various French research institutions to study the technologies of ancient civilizations.
Satellite imagery shows the enclosure perfectly intersects the dry bed of the Abusir Wadi, a seasonal stream that flowed from the mountainous western desert down to Saqqara and into the Nile. Also, the Gisr el-Mudir has all the technical characteristics of a "check dam," used to control the flow of flash floods from the wadi and capture heavy sediments like trees and boulders that could damage the settlements and monuments downstream.
"Anyone familiar with the hydraulic field, even a first-year student, would recognize the profile of a check dam," Landreau tells Haaretz. But why build a dam on the edge of the desert, you ask?
We must remember that the Third Dynasty ruled during the tail-end of the last so-called Green Sahara period, a cycle in which parts of the Sahara and Arabia had become a lush, green savannah. This era, also known as the African humid period, ended around 5,000 years ago. But conditions along the Nile valley when Djoser reigned, in the 27th century B.C.E., were still wetter than today, Landreau and colleagues aver.
Previous research has already shown evidence of violent floods in the Abusir Valley during the time of the Third Dynasty, they add.
"Before the Fourth Dynasty it is likely that there were more problems with floods than with lack of water," Landreau notes.
It should also be noted that recent research has shown that, during the Old Kingdom, the Nile had an additional branch, now extinct, which ran a few kilometers west of the present-day river course, much closer to the pyramids of Giza and Saqqara. This would help explain why the Old Kingdom pharaohs built these massive monuments seemingly on the edge of the desert rather than closer to the river.
The extinct branch would have been an invaluable waterway to bring materials and people to the building sites. Landreau agrees with the research showing that the extinct branch existed but, because the Saqqara Plateau is elevated from the Nile Valley, it would still make sense for the site's water supply to come from the mountains to the west, flowing naturally through the Abusir, rather than to be artificially lifted from the Nile below.
Map of the Saqqara plateau showing the water course from the Gisr el-Mudir dam to the water treatment facility near Djoser pyramid. The water is then transferred to the pyramid's network of pipes to power the hydraulic elevator.Credit: Paleotechnic of Paris, France, C
Pharaoh's Brita filter
Once the waters of the Abusir were tamed by the dam, they would probably pool in an artificial lake and enter the next monumental engineering work that the Egyptians came up with.
As mentioned, Djoser's complex is surrounded by a shallow dry moat, which most researchers believe provided the stones for the pyramid and the surrounding buildings.
But to the south of the complex, the moat suddenly deepens into a trench. The rock-cut depression, 400 meters long and 27 deep, forms at least three successive underground compartments, which have only been partially excavated. The function of this trench is unexplained, though some Egyptologists believe it might have had some spiritual significance (there is an old joke about archaeologists interpreting anything they can't understand as evidence of cultic activity).
To the eye of the trained hydraulic engineer, the deep trench is a traditional water purification system, used to clear sediments from roiling floodwaters: water goes into the first compartment, sediment settles at the bottom, and only the overflow from the top passes to the next compartment, where the process is repeated, Landreau explains. That's why there are drinking wells connecting the surface to the third compartment, where the water would have been cleanest and could have been used to quench the thirst of the locals, he says.
The second compartment in this complex water treatment plant also would have been connected to a network of 7 kilometers of pipelines that run under Djoser's complex – another enigmatic feature of the monument.
One pipeline leads directly to a vertical shaft that is 28 meters deep and rises in the center of Djoser's pyramid. At the bottom of the shaft archaeologists unearthed a box made of granite blocks, with a hole and a large stone blocking the aperture.
The identified building process of the step pyramid: A hydraulic lift mechanism.
Credit: Landreau et al., 2024, preprint Researchgate
It's a plug, not a sarcophagus
Because this shaft housed human remains, early researchers interpreted it as the pharaoh's burial chamber, and the granite box as his sarcophagus.
Then a 1994 radiocarbon study of the remains showed they were from a much later period and could not belong to Djoser, and were most likely the result of a reuse of the pyramid.
Actually, the granite structure was a maneuvering chamber that could be filled with water to raise an elevator (likely made of wood, and therefore long decomposed) up into the center of the work-in-progress pyramid, Landreau and colleagues posit. The round stone, functioning as a giant plug, could be raised using ropes to fill the chamber with water – then the chamber would be drained and the plug replaced for the lift to descend.
The shaft, granite box and plug at the center of Djoser's pyramid
PaleotechnicCredit: 3D Quantum Innovations
At least some of the pyramid's 2.3 million limestone blocks, each weighing an average 300 kilograms, may have been raised this way, Landreau and colleagues conclude.
It's not that more known and traditional methods, like ramps and sledges, were necessarily not used. But this may have simply been another system invented by the brilliant Imhotep, the famed architect to whom the construction of Djoser's pyramid is attributed, Landreau notes.
A virtual reconstruction of the maneuvering chamber for the water elevator
PaleotechnicCredit: 3D Quantum Innovations
It is hard to determine the exact amount of rainfall in the area during the Third Dynasty, and the Abusir river was likely a seasonal one also during the wetter climes that Djoser's reign enjoyed, Landreau says. The lift may have operated only for part of the estimated 20 years that the construction of the pyramid required, he says.
"Still, if I were an architect I would not rule out another possible method of construction," he says, adding that because some of the water management structures, like the dam, are believed to date to before Djoser's reign, it is possible that Imhotep reused or built upon a preexisting system.
The next step that the French team of ancient technologists is working on is to understand whether the harnessing of water power was also used to help construct the other later pyramids of the Fourth Dynasty, especially the behemoth that is the Great Pyramid of Cheops, or whether the progressively dryer conditions made this method unfeasible. Only time and more research will tell whether Djoser's brilliant water lift was a red herring or something more systematic that can help explain the broader mystery of how all the Egyptian pyramids were built.
-- Sent from my Linux system.
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