Egyptians Used Wet Sand to Move Stones to Build Pyramids

New research suggests that Egyptians used wet sand to move large stones to build the pyramids.

Ancient Egyptians' ability to haul large rocks to build the Pyramids has baffled scientists for several centuries. Many theories have been proposed to explain how an ancient civilization could construct such massive structures. One theory suggests that the pyramids were built inside out. Others say that aliens built them.

A new study has found that Egyptians used a nifty trick; they used wet sand in front of the sledge to move the large stones.

Wet sand not only prevented the formation of sand berm, but also cut the pulling effort by half. The study was conducted by Physicists from the FOM Foundation and the University of Amsterdam, Washington Post reported.

For the study, researchers created a version of the sledge used by the Egyptians. The sledge was placed in a tray of sand. The team used a rheometer to determine the stiffness of the sand, according to a news release. 

They found that the pulling force decreased with a decrease in sand stiffness. According to the researchers, water droplets act like tiny capillary tubes in the sand. The right amount of water could make the sand less stiff, enabling the men to pull the stones with half the effort.

"I was very surprised by the amount the pulling force could be reduced - by as much as 50 percent - meaning that the Egyptians needed only half the men to pull over wet sand as compared to dry," Daniel Bonn, one of the study authors, told the Washington Post.

Egyptian painting in the tomb of Djehutihotep shows a person pouring water in front of a pulsed sledge.

The research doesn't just show how ancient people probably constructed the pyramids, but also reveals that scientists haven't fully understood the mechanics behind granular movement. Materials such as sand, concrete and coal are ubiquitous. And, learning about their behavior could cut transport and energy costs.