Pyramid Quest (15 page)

Sneferu, Khufu’s father and the purported builder of three pyramids, first organized the labor pool for this pyramid-building industry. He had conquered the armies of Nubia, or modern Sudan, and driven some 7,000 defeated men, along with their families and animals, into Egypt. Rather than let these new subjects spend their days idling about and causing trouble, Sneferu turned them into Egyptian citizens and encouraged them to become skilled workers who benefited from a system of privilege. A stela Sneferu erected at Dahshur explains how he did it: “The settled Nubians working on the two pyramids of Sneferu are given tax exemption.”
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But how did they actually erect pyramids? How did they raise all that stone into the sky and line it up so precisely?

On the issue of how the pyramids were actually constructed, Herodotus, who never laid claim to being an engineer, is more than a bit vague. His phrase “machines made of short pieces of wood” tells us so little that Egyptologists for decades have dismissed the description as too flawed to be useful. They have come up with their own ideas, which are all variants of that mainstay of high-school physics: the inclined plane. They call it a ramp.

The ramp theory has any number of variants, but they all fall into one of three basic concepts. The first is a long, straight ramp that slopes up against one face of the pyramid. The workers placed stones on sledges and dragged them uphill in gangs. The advantage to this ramp strategy would be that three sides and all four corners would remain unobstructed and make it easier for the builders to keep the structure square and true. The problem is that as the pyramid grew, the ramp would have to extend an incredibly long distance. To preserve a slope of 1 in 10 all the way to the top of the Great Pyramid, the ramp would have to reach approximately 1,600 yards, or almost a mile.

To solve the length issue, some Egyptologists have argued for a spiral ramp. Four ramps, each beginning at a corner of the pyramid, spiraled upward and rested for support on the outer casing blocks.

A third idea combines the straight and spiral ramps. A straight ramp ran from the mouth of the Giza limestone quarry to a point about 100 feet up the Great Pyramid, then a spiral ramp climbed the rest of the structure’s height.

All three ramp ideas suffer from fatal flaws. There is the length problem with the long ramp, of course. There is also a major issue with volume and mass. Even if the slope were a relatively steep 1 in 7, a ramp that reached from ground level to the apex of the Great Pyramid would require over 5.5 million cubic meters of material. That’s more than twice the volume of the Great Pyramid itself!

And what could such a ramp be built with? Mud brick or tamped earth would collapse under its own weight and years of heavy traffic before the ramp reached its maximum height. Rock chips or trimmings from the pyramid would also prove as unstable as scree deposited at the base of a cliff. The only workable alternative is dressed stone, which means that the Egyptians would have had to build a ramp more than twice as big as the Great Pyramid in order to erect the Great Pyramid itself. As close to the Stone Age as they were, the Old Kingdom Egyptians would have quickly figured out that this approach amounted to an engineering black hole.

The spiral ramp, even when combined with a long ramp, is no better a solution. As the ramp rose with the growing pyramid, the distance between turns would decrease at each level, and the ramp would become steeper and steeper. In addition, the corners would be so sharp that the workers, no matter how large or muscular their gangs, could not drag the stones around them. With nothing but the outer casing stones for support, ramps would soon crumble away or fracture into uselessness. A spiral ramp would have also obscured the sides and corners of the pyramid and made it impossible to check squareness and alignment. Had they used a spiral ramp, the builders might have pulled it down at the end—itself a major feat of demolition and waste disposal—only to find they had erected something that was far from the near perfection seen in the existing pyramids. The Egyptians clearly knew better.

One alternative theory, promoted in, among other sources, a 1988 book entitled
The Pyramids: An Enigma Solved,
by Joseph Davidovits and Margie Morris, and in Moustafa Gadalla’s
Pyramid Handbook,
is that the Egyptians didn’t cut and lift stones. Rather, what we think of as stones are in fact molded blocks made of high-quality, manufactured limestone concrete. The pyramid builders made this material by combining silico-aluminate cement mortar with fossil-shell limestone in much the same way that modern-day cultured marble is made by mixing ground limestone into a polymer base. The Egyptians hauled materials up the pyramid, the way hod carriers do on contemporary construction sites, and cast their “stones” where and when they were needed. Herodotus’s “machines” should actually be translated as “molds,” Gadalla writes.

Of course, casting the masonry wouldn’t actually solve entirely the pyramid construction problem. Even if the Egyptians were pouring stones rather than hauling them as blocks, they would still have to haul the same mass of material up the pyramid in the form of mortar and fossil-shell limestone. Admittedly, it might be easier to haul as small bundles of rubble rather than large blocks, but a lot of work and time would still be involved.

Yet, even though this strategy offers little advantage, Gadalla cites a variety of evidence to support it. He maintains, for example, that the Great Pyramid’s building blocks do not match the Giza limestones and that the copper tools the Egyptians used couldn’t cut enough limestone to build the structure within a single pharaoh’s lifetime.

Gadalla is wrong on both counts. Other geologists and I have studied the pyramids and ancient quarries (which retain evidence of the ancient rock-cutting activities), and we know the natural sources of the stone used in the Great Pyramid and the methods used to remove it from the quarry and transport it to the building site. Both fell well within the technological competencies of the Old Kingdom.

The inner core of the Great Pyramid was assembled from blocks of yellowish limestone quarried at Giza. This stone is relatively easy to remove because of the weak zones and planes natural to this particular limestone. Limestone is a sedimentary rock; it often forms from the layered accumulation of shells and other calcareous materials. The Egyptians learned to exploit the relatively weak zones between certain layers of limestone and peel the rock off stratum by stratum. They dug a grid of trenches cross-hatching the limestone deposit, each trench just wide enough to allow a stonecutter to mark the blocks and cut them to the same approximate depth. Then, starting with the row of blocks on the end, a wedge—probably made of hard wood, like acacia, sheathed in copper—was driven into the weak zone marking the layer, and the block was split from the underlying rock. The quarrymen then dragged the freed blocks one after another over a layer of quartz sand spread over the quarry surface. This abrasion smoothed the tops of the next layer of blocks, which were then trenched and removed just as the layer above had been. The whole procedure exploited limestone’s natural characteristics, and it produced blocks that, layer by layer, were of roughly the same dimensions. Various courses of the Great Pyramid are of different thicknesses, reflecting the origin of the blocks in strata whose depth varied naturally.

The fine white limestone that made up the outer polished and finely fitted outer layer didn’t come from Giza. Its source was the Mokattam (Mokhattam, Muqattam) Hills (Jebel Mokhattam), on the other side of the Nile, near the modern cities of Tura and Maasara.
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This stone was harder to remove than the Giza material, because it lay under the surface and could be mined only by digging tunnels, some of which went more than 50 yards below ground level. The quarrymen removed the limestone in a steplike fashion, wedging the blocks off and tumbling them down. The stone could be further trimmed and shaped with copper chisels and short, single-handed saws bearing a blade about
inch thick.

The rock that caused Egyptian masons the greatest difficulty was the granite used in a few parts of the Great Pyramid, such as the King’s Chamber. An igneous rather than a sedimentary rock, granite is much harder than limestone. Yet even it has weak points, natural cleavage lines that carve the stone into pieces with usable shapes. At Aswan, one of the principal sources for the granite used in the Great Pyramid, the rock bed breaks apart in layers that are nearly parallel and take a variety of shapes, including blocks, beams, and balls. Egyptian stonemasons could work these stones into the forms they needed.

Not that this didn’t take a lot of elbow grease and sweat. Granite is so hard and difficult to work that it was reserved for those areas of the Great Pyramid, such as the great beams roofing the Relieving Chambers, where its ability to span an unusual distance or support great weight was required. Still, when they needed granite, the Egyptians knew how to prepare it for use. The process began with handheld balls of dolerite, a stone harder even than granite, which the stonemason pounded against the rock. A block could be further shaped by sawing, as is evidenced by the granite coffer or sarcophagus in the King’s Chamber, which shows signs of having been cut with a blade at least 8 feet long. Copper by itself is too soft to cut granite. Hard sharp materials, such as bits of diamond, may have been inserted into the blade, or a slurry of sand, emery, or diamond dust could have been worked into the cut.
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Experimental trials of such devices have shown that they work, and the Egyptians could have used them to create the masonry we see today throughout the Great Pyramid.

Once the blocks of limestone or granite were quarried and at least roughly shaped, they next had to be transported to the building site. For the limestone, it was but a short distance from the quarry to the pyramid. The granite, however, was floated down the Nile from Aswan in Upper Egypt. Very few depictions of working wheels are known from the Old Kingdom. The archaeological evidence to date indicates that the Egyptians of the pyramid-building era most likely transported stone blocks on sledges rather than wheeled vehicles. Depictions from the Eighteenth Dynasty show oxen dragging a stone block on a sledge and groups of men pulling sledge-mounted, heavy funerary statues of the dead. The single bas relief showing the transport of the 58-ton stone colossus of Djehutihotep has 178 men roped to a massive sledge with four hawsers and supplying the power. In most of these images, including that of Djehutihotep, an individual pours liquid in front of the sledge. Perhaps this libation served a symbolic purpose; it may have also been practical. Covering the route with silt that was wetted just before the sledge slid onto it would have reduced friction and made pulling that much easier. And, although few rollers have been found in ancient Egypt, the stone transporters of the Old Kingdom did use wood tracks.

Sledges moved the Giza limestones to the building site, and the Tura and Aswan blocks to the Nile, where they could be barged to the plateau, then sledged up from a riverside dock to the growing pyramid. But once they were there, they still had to be lifted up and put into the right place. A ramp wouldn’t solve that key problem for the pyramid builders of ancient Egypt. What method or tool did they use?

There is the thing itself; then there is the story about the thing. In the case of the lever, the story dates to the third century B.C., when the Greek mathematician and engineer Archimedes (287?-212 B.C.) first described it. The lever did not, however, begin with Archimedes. His genius lay in figuring out its physics. The lever had been around for a long, long time, and it was an understanding of its usefulness and power that led to the quotation ascribed to Archimedes centuries after his death: “Give me a place to stand, and I can move the earth.”

The earth is vastly larger than even the biggest block of stone in the Great Pyramid, and the lever is the key to how each of the more than 2 million stones in the monument were moved into place. This is the hypothesis advanced by Peter Hodges in his 1989 book
How the Pyramids Were Built.
I find his approach convincing.

Hodges came to the pyramid-building problem not as an antiquarian scholar but as a man who spent his life in construction. He trained professionally at the School of Building in Brixton, England, then served with the British Army’s Royal Engineers as a sapper officer dealing with field fortifications during World War II. When peace came, he worked with a number of building firms and eventually took over and ran a long-established construction business. He understood building from the inside and knew firsthand how it feels to work stone with hand tools. Still, when Hodges came to Egypt, he accepted the ramp theory of construction. Given how many eminent academics accepted it, why wouldn’t he?

Then, as always happens in construction, anything that can go wrong will. Staying in a hotel within sight of the Great Pyramid, Hodges was felled by a dose of dysentery that gave him three full days flat on his back to think about how the builders of the Old Kingdom would go about putting up a pyramid. In that time, he figured out the basis of his approach, which he elaborated over the following years and developed into a book that was published after his death.