Study suggests Egyptians used hydraulic lifts to build Pyramid of Djoser

It's long been a hotly debated open question regarding how the great pyramids of Egypt were built, given the sheer size and weight of the limestone blocks used for the construction. Numerous speculative (and controversial) hypotheses have been proposed, including the use of ramps, levers, cranes, winches, hoists, pivots, or any combination thereof. Now we can add the possible use of a hydraulic lift to those speculative scenarios. According to a new paper published in the journal PLoS ONE, ancient Egyptians during the Third Dynasty may have at least partly relied on hydraulics to build the Step Pyramid of Djoser.

"Many theories on pyramid construction suggest that pure human strength, possibly aided by basic mechanical devices like levers and ramps, was utilized," co-author Xavier Landreau, of Paleotechnic in Paris and Universite Grenoble Alpes, told Ars. "Our analysis led us to the utilization of water as a means of raising stones. We are skeptical that the largest pyramids were built using only known ramp and lever methods."

The Step Pyramid was built around 2680 BCE, part of a funerary complex for the Third Dynasty pharaoh Djoser. It's located in the Saqqara necropolis and was the first pyramid to be built, almost a "proto-pyramid" that originally stood some 205 feet high. (The Great Pyramid of Giza, by contrast, stood 481 feet high and was the tallest human-made structure for nearly 4,000 years.) Previous monuments were made of mud brick, but Djoser's Step Pyramid is made of stone (specifically limestone); it's widely thought that Djoser's vizier, Imhotep, designed and built the complex. The third century BCE historian Manetho once described Imhotep as the "inventor of building in stone." As such, the Djoser Pyramid influenced the construction of later, larger pyramids during the Fourth, Fifth, and Sixth Dynasties.

Using limestone was a much more labor-intensive process than constructing mud-brick monuments. Unfortunately, there just aren't many historical sources from this period to shed light on how these pyramids were built. Herodotus in the fifth century BCE—centuries after the great pyramids were built—described the use of a machine consisting of one or more levers to raise blocks of limestone. In the first century BCE, Diodorus Siculus mentioned the use of earthen ramps, claiming that "machines for lifting had not yet been invented in those days."

Archaeologists have found evidence for the use of small ramps and inclined causeways at the Great Pyramid of Giza, among others, but it's likely other supplementary methods or devices were used, with levering believed to be among the strongest candidates.

Perhaps most controversially, French architect Jean-Pierre Houdin constructed an archetypal model of the Great Pyramid of Giza to demonstrate how an external ramp could have been used to build the first 30 percent of the structure, before switching to an internal ramp to move stones higher up. He explained the lack of evidence for such ramps by suggesting that the external ramp stones had been recycled to build the upper levels. (The 2017 video game Assassin's Creed Origins incorporates Houdin's controversial theory in its virtual tour of the Great Pyramid.) It's worth noting that Egyptologist David Jeffreys of University College London once dismissed Houdin's hypothesis as "far-fetched and horribly complicated," and it remains unproven.

A water elevator?

According to Laundreau, at the outset, his interdisciplinary team of hydrologists, limnologists, geologists, satellite imagery specialists, and so forth wasn’t looking for evidence of a hydraulic system within the Djoser pyramid. They just set out to map the watersheds to the west of the Saqqara plateau. Four years of intensive research led them to the discovery of structures they believe constituted a dam, a water treatment facility, and a possible internal hydraulic lift system within the pyramid as part of the complex. “It was by following the thread of the water that we gradually understood the meaning of those structures and built up an understanding of the whole,” he said.

For instance, they concluded that the massive Gisr el-Mudir enclosure has all the requisite features of a check dam, capable of trapping sediment and water. There is topographical evidence of a possible lake just west of the Djoser complex and evidence of possible water flow in the "dry moat" surrounding it. That moat has a 410-meter-long channel called the Deep Trench in the inner south section that Laundreau et al. suggest has all the technical requirements for a water treatment facility, namely a settling basin, a retention basin, and a purification system.

Ancient Egyptians certainly used hydraulics in the canals they built for irrigation and for barges to transport stones. There is evidence that the region had more water resources available at the time the Step Pyramid was built—more of a savannah environment than the dry desert clime of today. So those waterways could once have been actively used to channel runoff from heavy rainfall.

The biggest stretch in Landreau et al.'s theory is the existence of a floating wooden elevator inside the pyramid as it was being constructed, relying on the aforementioned water flows to lift the platform up a central vertical shaft. The pyramid's inner structure features at least 13 shafts, most notably two twin shafts at the north and south of the complex, per the authors. Their ground-penetrating radar images revealed that these two shafts are connected by a 200-meter-long tunnel. At least two shafts on the east side are connected to the supposed eastern section of the dry moat by two 80-meter-long pipes.

Prior excavations in the 1930s removed most of the materials that filled the twin shafts, apart from two granite boxes, one at the bottom of each, so the authors had to rely on those archaeological reports for information about the internal layout of the shafts. They found evidence of a removable plug system they believe could have allowed the shafts to fill with water when it was opened, lifting a floating wooden elevator platform laden with limestone blocks. Closing the plug and draining the shafts would lower the platform for the next load. Landreau et al. estimate that Egyptian builders could have captured between 4 million and 54 million cubic meters of water over the two or three decades it took to complete the Step Pyramid.

There might have been periods where there simply would not have been enough water to operate such a hydraulic lift system, so the authors do acknowledge that such a device might have complemented other construction methods. "In accordance with other studies, we cannot assert that only one exclusive technique was used," said Landreau. "We estimate the beginning of the pyramid building could be performed using ramps prolonging the path from the local quarry. Furthermore it does seem logical to consider that the pyramid's architects and overseers employed various construction techniques at their disposal, including ramps, lifting cranes, or animal force. These different techniques would have allowed for the versatility of construction and adaptability to the various constraints of the site."

Landreau pointed out that there were later pyramids that were as tall and heavy as the Step Pyramid, but they were not built with large cut stones—instead, the builders used smaller stones and bricks that turned to rubble over the ensuing millennia—so they did not have the same longevity. In fact, “Not a single Pharaoh from the Middle and late Old Kingdom, or the Middle Kingdom, managed to build another wonder like those from the 4th dynasty,” he said. “While there are valid historical arguments for this, it's also possible that the lack of the energy source, which aided the ancient builders, played a role. The climate during the early Old Kingdom was wetter, but it became drier with time. As the hydraulic force from the wadis diminished, the later Pharaohs may have struggled to replicate the massive pyramids of earlier dynasties using only human strength.”

Landreau and his team are already contemplating possible next steps to bolster their hydraulic lift hypothesis. For instance, there should be more detailed research into the water resources of ancient Egypt to crosscheck what he admits are his team’s “crude computations,” given how the region shifted from a savannah to a desert environment. New geophysical surveys and coring of the wadi would shed more light on the hydrological aspects of the area, while other surveys might reveal where the eastward tunnels of the pyramid lead.

Furthermore, excavations around Gisr el-Mudir and the Deep Trench could clarify whether they had hydraulic uses, especially if any evidence of a water imprint were found, along with conduits and tunnels between the compartments, such as between the Deep Trench and the south shaft. Perhaps muon tomography could be used to explore the upper part of the north shaft. Looking for evidence of internal structures like shafts in other pyramids might prove informative as well.

The skeptics weigh in

This is not the first time someone has suggested that hydraulic methods might have been used to build Egyptian pyramids, according to John Baines of Oxford University. Baines told Ars that he was “agnostic to skeptical” about the hydraulic lift hypothesis presented by Landreau et al., although he felt it was more solid than prior, shakier claims. “But it’s another matter whether it’s plausible,” he said. “Using ramps is known to work and there is archaeological evidence for them from other sites.”

"The paper is certainly very thorough and the hydrographic arguments may be compatible with recent work on higher levels of rainfall in the relevant period and different patterns of the Nile, for example," Baines added. "There is also the Sadd el-Kafara dam ("Dam of the Infidels") not very far away and from the same general period, though the original 1950s report on that said it failed at the first hurdle."

He finds Landreau et al.'s arguments about water filtration and water quality more problematic. "Can one point to anything beyond preference for well water or flowing water over standing water before quite modern times?" he said. "I also wonder about how far levels could have been surveyed with the necessary accuracy in the early third millennium."

Judith Bunbury of the University of Cambridge told Ars that there is evidence that Egyptians used other kinds of hydraulic technologies around that time, but there is no evidence of any kind of hydraulic lift system.

"While information from this period is sparse, it is not absent, and it is surprising when so many other details of daily life and technologies are recorded in the Old Kingdom tomb scenes and texts like the Red Sea Scrolls, that this type of device is omitted if it were in use," she said. "For example, at Gebel al-Asr, in the time of Khufu, loading ramps were in use, moving large statue blocks. There are still some large statue blocks in situ with remains that show that they were moved by a lever and chock method, still used by Egyptian workmen today. In this context, it would be surprising if a powerful technology, like a hydraulic lift, was used and then so quickly forgotten."

That’s why Bunbury would like to see other evidence in support of Landreau et al.'s hypothesis, most notably images of such a device or historical texts referring to the use of a hydraulic lift. Remains of other examples of such a lift would also be convincing, although Bunbury cautioned that "wells and Nilometers also required vertical shafts, and deep vertical shafts were common for burials—even those with no super-structure." So it would be challenging to convincingly argue for a hydraulic purpose for such shafts over other possible uses.

PLoS ONE, 2024. DOI: 10.1371/journal.pone.0306690  (About DOIs).