Egyptian pyramids are a wonder that have left scientists and engineers scratching their heads. How did heavy rock slabs get placed — higher and higher — to construct the iconic shape?
It seems we may have an answer, and it wasn't aliens after all. Researchers have uncovered a sophisticated ramp system dating back 4,500 years. Located at Hatnub, a rock quarry in Egypt's Eastern Desert, the ramp was used to transport massive alabaster stones up steep angles and into place during pyramid construction.
"This kind of system has never been discovered anywhere else," said Yannis Gourdon, co-director of the expedition, which also included archaeologists from the French Institute for Oriental Archaeology in Cairo and from the University of Liverpool in England.
Based on the tool marks and inscriptions, the group matched the ramp's age and conscription with the reign of Khufu, the pharaoh who called for the construction of the Great Pyramid, which is the largest of the three Giza Pyramids. It also turned out to be the world's largest pyramid.
"This system is composed of a central ramp flanked by two staircases with numerous post holes," Gourdon said in a statement. "Using a sled which carried a stone block and was attached with ropes to these wooden posts, ancient Egyptians were able to pull up the alabaster blocks out of the quarry on very steep slopes of 20 percent or more."
The ropes allowed rock-movers to multiply their efforts, making it possible to pull a sled up the ramp, even though the sled was topped with a rock that weighed an average of 2.5 tons (2.3 metric tons).
Egyptologists have surmised for some time that ramps were used when the pyramids were built. However, the discovery of this ramp system shows that the stones were hauled at a far steeper angle than was previously suspected.