How did ancient Egyptians stack the heavy stones of the oldest pyramid? Scientists propose a new theory

(CNN) – Egyptologists have been hotly debating for years how the massive pyramids of ancient Egypt were built more than 4,000 years ago. Now a team of engineers and geologists has put forward a new theory: a hydraulic lifting device may have floated the heavy stones through the centre of Egypt's oldest pyramid using stored water.

The ancient Egyptians built the Step Pyramid for Pharaoh Djoser in the 27th century BC, and it was the tallest structure at the time, standing at about 62 meters (200 feet) high. But how exactly the monument, made from a series of stones weighing 300 kilograms (about 661 pounds), was erected has remained a mystery for centuries, according to the study published Monday in the scientific journal Plus 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 of the Middle and New Kingdoms (1980 to 1075 BC),” said lead author Dr. Xavier Landreau, director general of Paleotechnica private research institute in Paris that studies ancient technologies.

“The techniques involved could include ramps, cranes, cranks, lever lifts, hoists, pivots, or a combination of these methods,” he added in an email. “But what about the pyramids of the Old Kingdom (2675 to 2130 BC), which are much larger? While human power and ramps may have been the only building force for the small structures, other techniques may have been used for the large pyramids.”

The new work, which uses an interdisciplinary approach, is the first to report a system consistent with the internal architecture of the Step Pyramid, the authors wrote.

A complex water treatment system based on local resources would have allowed for the existence of a water-powered elevator within the pyramid's internal vertical shaft. According to the study, some kind of float would have lifted the heavy stones through the center of the pyramid.

While the theory is an “ingenious solution,” some Egyptologists are not convinced by it, as a more widely held theory is that ancient Egyptians used ramps and transport devices to move the heavy blocks into place, says 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.

Analyzing available data, such as paleoclimatology, the study of ancient climates, and archaeological data, the study team suggested that water from ancient streams flowed from the west of the Saqqara Plateau into a system of deep-water ditches and tunnels that surrounded the Step Pyramid.

Water would also have flowed into the Gisr el-Mudir, a rectangular limestone structure measuring 650 by 350 metres, which would have acted as a retaining dam. Previously thought to be a fortress, a celebration arena or a livestock enclosure, this device would have controlled and stored floodwaters, as well as filtering out sediment and dirt so that they would not block water passages.

The theorized water treatment system would not only allow for water control during floods, but would also “ensure adequate quality and quantity of water for both consumption and irrigation, as well as for transportation or construction,” says study co-author Dr. Guillaume Piton, researcher from the French National Research Institute for Agriculture, Food and the Environment (INRAE), based at the Institute of Environmental Geosciences at the University of Grenoble Alpes.

The authors cited several Previous studies According to some, the Sahara Desert experienced more regular rainfall thousands of years ago than it does today. Instead, the landscape resembled a savannah, which could support more plant life than the arid conditions of the desert. However, there is debate about exactly when the climate conditions were wetter.

According to Judith Bunbury, a geoarchaeologist at the University of Cambridge, London, who was not involved in the new study, there may have been enough water for a system like the hydraulic lift. Bunbury noted previous research which found that gutters for rainwater were built and used in the Old Kingdom, as well as previous studies that analyzed the diet of birds of the time, which consisted of wetland species such as frogs.

“I think there is a fairly widespread belief that it was rainier in the Old Kingdom, especially in the early Old Kingdom when the Step Pyramid was being built,” he added.

On the other hand, experts debate whether there was enough consistent rainfall to fill the structures that would have supported the hydraulic elevator, such as the “Dry Ditch,” a giant channel surrounding the Step Pyramid and nearby structures, which the authors believe collected water that helped power the elevator when it was in use.

According to Jeffreys, the Sahara's greenest period most likely ended in the early third millennium B.C.E. The scant rainfall could not fill the structures to the extent necessary for a hydraulic lift, and it could not keep up with the rate of water loss within the structure's 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.

“The climate became more humid (seasonal – winter rains) in northern Egypt (also at Saqqāra) during the Third Dynasty (2670-2613 CA), but their intensity was relatively low. These rains, even if they filled the wadis (a valley that is dry except in the rainy seasons) with water, would not have been able to fill the dry moat even to a small extent… these waters would have been immediately drained by gravity into the depths of the rock mass, about which there is no doubt (unless it was a biblical flood),” Welc said in an email.

The authors of the study agreed that it is highly unlikely that the system was permanently filled with water and argue that it is more likely that flash floods at the time could have provided enough water to support the hydraulic lift during the pyramid's construction. However, the authors note in the study that further research is needed to know exactly how much rainfall and flooding likely occurred during this time.

This is not the first time that there has been an investigation into whether the Nile played a role in the construction of the pyramids. In a study Published in May, a dried-up branch of the massive river was discovered and it is theorized that it was probably used to transport huge limestone blocks to the construction sites of several pyramids. According to Jeffreys, there are also indications that the ancient Egyptians used hydraulics on a smaller scale.

Researchers had not until now determined a clear purpose for the vertical shaft inside Zoser's pyramid. Some later pyramids, such as the Great Pyramid of Giza, have shafts that are thought to have been used for ventilation, and it's possible that the inner shaft could also have been intended for lighting or to relieve pressure in the chamber below, Jeffreys said. But as the first of its kind, the step pyramid was an experimental structure that is thought to have begun as a mastaba (a flat tomb) and was built, so it is not clear exactly what its internal features were intended for, he added.

The shaft inside the step pyramid is connected to a 200-meter-long underground tunnel that connects to another vertical shaft outside the pyramid. The outer shaft could then connect to a hypothetical water-transport section of the Dry Ditch, known as the Deep Ditch, but more research is needed, the authors wrote in the study.

The inner shaft begins directly beneath the pyramid, near the center, where there is a granite box with a plug at its base. This box is thought to be King Djoser's burial chamber, but the authors suggest it was built for the purpose of opening and closing the hydraulic lift, allowing water to fill the shaft when in use.

As to whether other pyramids were built using this method, Landreau said more research is needed. “It may hold the key to unlocking the mystery of how the largest monoliths, found at pyramids such as Cheops or (Khafre). These monoliths weigh tens of tons, making it seem impossible to transport them using only (human labor). In contrast, a moderately sized hydraulic lift can lift 50 to 100 tons. Exploring hidden wells within these pyramids could be a promising avenue for research,” he added.

Despite the more than 4,000-year-old mysteries surrounding the pyramids and their features, there is sufficient documentation that ancient Egyptians used certain technologies such as scaffolding and mud-brick ramps to aid in the construction of various structures, University of Cambridge geoarchaeologist Bunbury explained, while there is no documentation or depictions of a water-powered lifting device that she is aware of.

“I think people, even from ancient times, have been inspired by the pyramids as a giant construction project,” Bunbury said. “And they find it quite hard to believe that they were built by ordinary people at the time, partly because they see it as something from so long ago. … It’s baffling that there are so many proposals for what could be some kind of technological innovation that were then dismissed, when we know that they had technical solutions for these things anyway.”

“It doesn’t mean that (the hydraulic lifting device) hasn’t been used,” he said. “But there is a kind of razor blade Occam “what is the simplest thing based on what we already know.”