Pyramid builders could have used rolling blocks

Egypt’s pyramid construction plans could have included a little rock ‘n’ roll.

Ancient Egyptians might have rolled giant bricklike stones to pyramid building sites by strapping wooden rods to each rock, researchers suggest in a paper posted August 14 at arXiv.org.

The method offers a new take on a herculean task that has long puzzled people. The rolling hypothesis could even dodge potential complications with the leading theory: that Egyptians slid blocks along slippery paths.

Physicist Daniel Bonn of the University of Amsterdam, who has studied the mechanics of the sliding technique, thinks the rolling method could probably work. “Technically, I think what they’re proposing is possible. But technically, a lot of things are possible.”

Over 4,000 years ago, ancient Egyptians hefted over 2 million limestone blocks into place to build the Great Pyramid of Giza. Each massive stone was on average about 1.3 by 1.3 by 0.7 meters and weighed 2,500 kilograms — about as much as a Chevy Tahoe. Egyptians hauled each of these blocks a kilometer or so from the quarries to the construction site. Many researchers think workers loaded the blocks onto sleds and pulled them along a sort of Slip’N Slide, a ramp slickened with wet clay or cattle fat.

Some evidence supports the theory: Scientists have found the remains of ramps built out of sand, clay and fist-sized chunks of limestone, and traces of fat in soil near the pyramids. What’s more, ancient tomb and temple drawings depict Egyptians transporting enormous statues on sleds.

But while watching a TV special in which archaeologists used the sled method to construct a small-scale pyramid, physicist Joseph West of Indiana State University in Terre Haute had a new idea.

“I thought, well gosh, why don’t they just try rolling the things?” he says. Strapping wooden rods to four faces of a block, he thought, would turn it into a kind of rough wheel. “It should be a lot easier to roll than a square,” he remembers thinking.

He and two students tested the idea by lashing three wooden dowels to each side of a 30- kilogram limestone block, turning the block’s square cross section into a dodecagon.

Then the team rolled the block by placing it on a rope on the ground, like a spool of thread lying on its side. By wrapping one end of the rope around the block and pulling, the team could roll the makeshift wheel over grass, gravel and hard-packed dirt.

Rolling didn’t require much effort, the team found. The researchers needed about the same amount of force to keep the block rolling as people using the slippery road method needed to keep the sleds sliding.

Block rolling isn’t a completely new idea. Engineers had previously devised related techniques but didn’t collect force data.

Although West hasn’t tested a scaled-up version of his method, he thinks it has some potential advantages over sleds. Workers wouldn’t have had to carry water or fat to lube up the roadways ahead of the sleds, for one. And rolling the blocks may have caused less road damage than sleds, he suggests.

Instead of attaching wooden dowels to the blocks, Egyptians would have had to use thick posts about 30 centimeters in diameter — about the size of masts used on ships in the Nile, West points out.

At this point, the rolling theory is pure speculation, says Richard Redding, an archaeologist at the University of Michigan in Ann Arbor. “People see the pyramids as a great mystery,” he says. “They’re always coming up with new ideas about how they’re built.”