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Egyptologists have long debated how the massive pyramids of ancient Egypt were built more than 4,000 years ago. Now, a team of engineers and geologists has come up with a new theory: a hydraulic jack that would have driven the heavy stones through the center of Egypt’s oldest pyramid using stored water.
The ancient Egyptians built the Step Pyramid for Pharaoh Djoser in the 27th century BCE, and it was the tallest structure at the time, at about 62 meters (204 feet) high. But exactly how the monument, with some stones weighing 300 kilograms (about 661 pounds), was erected has remained a centuries-old mystery, according to the study published Monday in the journal PLOS One.
“Many detailed publications have discussed pyramid building procedures and provided tangible elements, but these tend to focus on more recent, better documented and smaller pyramids from the Middle Kingdom and New Kingdom (1980 to 1075 BC),” said lead author Dr. Xavier Landreau, CEO of Paleotechnic, a private research institute in Paris that studies ancient technologies.
“The techniques used here may include ramps, cranes, winches, elevating hoists, hoists, pivots, or a combination of these methods,” he added in an email. “But what about the Old Kingdom (2675 to 2130 BCE) pyramids, which are much larger? While human power and ramps may have been the only building forces for small structures, other techniques may have been used for large pyramids.”
The authors wrote that the new paper, which used an interdisciplinary approach, was the first to report a system consistent with the internal architecture of the step pyramid.
A complex water purification system using local sources would have allowed for a water-powered elevator in the pyramid’s internal vertical shaft. A kind of float would have lifted the heavy stones up to the center of the pyramid, the study said.
While the theory is an “ingenious solution,” some Egyptologists are not convinced, as a more widely accepted theory is that the ancient Egyptians used ramps and transport devices to move the heavy blocks into place, according to Egyptologist Dr. David Jeffreys, a retired senior lecturer in Egyptian archaeology at University College London who was not involved in the study. Here’s what experts have to say about the new theory.
The desert of Egypt was once savannah
By analyzing available data, including paleoclimatology, the study of ancient climates, and archaeological data, the research team proposed that water flowed from ancient streams from the west of the Saqqara plateau to a system of deep water channels and tunnels that surrounded the Step Pyramid.
The water would also have flowed into the Gisr el-Mudir—a rectangular limestone structure measuring a whopping 650 by 350 meters (2,133 by 1,148 feet)—which would have served as a dam. Previously thought to be a fortress, a festival arena, or a cattle ranch, the device would have controlled and stored water from heavy flooding, while filtering out sediment and debris to prevent it from clogging water passages.
The theoretical water purification system would not only have provided water control during floods, but would also have “guaranteed adequate water quality and quantity for consumption and irrigation purposes as well as for transport or construction,” said study co-author Dr. Guillaume Piton, a researcher at the French National Research Institute for Agriculture, Food and the Environment, or INRAE, based at the Institute of Environmental Geosciences at Grenoble Alpes University.
The authors pointed to several previous studies that showed that the Sahara Desert received more regular rainfall thousands of years ago than it does today. The landscape would have resembled a savanna instead, which could support more plant life than dry desert conditions. However, there is debate about exactly when climate conditions were wetter.
There would have been enough water to support a system like the hydraulic lift, said Dr. Judith Bunbury, a geoarchaeologist at the University of Cambridge in London who was not involved in the new study. She pointed to previous research that found rainwater gutters were built and used in the Old Kingdom, as well as previous research that looked at the diet of birds at the time, which consisted of marsh species such as frogs.
“I think there is quite a widespread belief that it was rainier in the Old Kingdom, certainly in the early Old Kingdom when the Step Pyramid was built,” she added.
On the other hand, experts debate whether there would have been enough consistent rainfall to fill the structures that would have supported the hydraulic elevator, such as the “Dry Moat,” a giant canal surrounding the Step Pyramid and nearby structures, which the authors believe collected water that helped power the elevator when it was in use.
The Sahara’s greener period likely ended in the early third millennium B.C., Jeffreys said. Low rainfall would not have filled the structures to the extent needed for a hydraulic lift, and it would not have been able to keep up with the water loss in the structures’ limestone, added Dr. Fabian Welc, director of the Institute of Archaeology at Cardinal Stefan Wyszynski University in Warsaw, Poland. Welc was not involved in the new study.
“There was a wetting of the climate (seasonal – winter rains) in northern Egypt (including at Saqqara) during the 3rd Dynasty (2670-2613 BCE), but its intensity was relatively low. These rains, even filling the wadis (a dry valley except in the rainy season) with water, would not have filled the dry moat even slightly … these waters would have been immediately drained by gravity deep into the rock massif, about which there is no doubt (unless it was a biblical flood),” Welc said in an email.
The study authors agreed that it is highly unlikely that the system was permanently filled with water, arguing that it is more likely that the flash floods of the time provided enough water to support the hydraulic lift during the pyramid’s construction. However, more research is needed to know exactly how much rainfall and flooding likely occurred during that time, the authors noted in the study.
This isn’t the first time the Nile has been studied for its role in pyramid construction. A study published in May found a dried-up tributary of the massive river and theorized that the stream was likely used to transport huge limestone blocks to multiple pyramid construction sites. There’s also some evidence that ancient Egyptians used hydraulics on a smaller scale, Jeffreys said.
Mysteries of Ancient Egyptian Structures
Researchers have not yet been able to establish a clear purpose for the vertical shaft in Djoser’s Pyramid. Some later pyramids, such as the Great Pyramid of Giza, have shafts thought to have been used for ventilation, and it’s possible the internal shaft was also intended for lighting or to relieve pressure on the chamber below, Jeffreys said. But as the first of its kind, the Step Pyramid was an experimental structure thought to have started as a mastaba (a flat tomb) and been built up, so it remains unclear what exactly the internal features were intended for, he added.
The shaft inside the Step Pyramid is connected to a 200-meter-long (656-foot-long) underground tunnel that connects to another vertical shaft outside the pyramid. The external shaft could then connect to a hypothesized water-transport section of the Dry Moat, also known as the Deep Trench, but more research is needed, the authors wrote in the study.
The internal shaft begins directly beneath the pyramid, near the center, where a granite box with a plug at its base stands. This box is generally considered to be the burial chamber of King Djoser, but the authors suggest that it was built to open and close the hydraulic lift, allowing water to fill the shaft when it was in use.
As for whether other pyramids were built using this method, Landreau said further research is needed. “It could be the key to unraveling the mystery of how the largest monoliths, found in pyramids like Khufu or (Khephren) were lifted. These monoliths weigh tens of tons, making it seem impossible to move them with (human labor) alone. Conversely, a medium-sized hydraulic elevator can lift 50 to 100 tons. Exploring hidden shafts in these pyramids could be a promising research direction,” he added.
Despite the more than 4,000-year-old mysteries surrounding the pyramids and their features, there is ample documentation that ancient Egyptians used certain technologies, such as scaffolding and mud-brick ramps, to aid in the construction of various structures, said Bunbury, a geoarchaeologist at the University of Cambridge. However, to her knowledge, there is no documentation or image of a water-powered lifting device.
“I think people, even since ancient times, have been inspired by the pyramids as a huge building project,” Bunbury said. “And they find it hard to believe that they were built by ordinary people at the time, partly because they see it as a long time ago. … It’s astonishing that there are so many proposals of what could be a technological innovation that have been dropped, when we know that they already had technical solutions for these things.
“That doesn’t mean (the hydraulic lifter) hasn’t been used,” she added. “But there’s a sort of Occam’s razor of what’s simplest, based on what we already know.”
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