Riddles of the Sphinx

Saving the Sphinx by Evan Hadingham

Reversing the damage

On a Sunday afternoon in February 1988, archeologist Zahi Hawass, at that time monuments inspector for the Giza Plateau, was urgently summoned to the Sphinx. A 700-pound chunk of the right shoulder had fallen off in front of a startled German newspaper reporter. Hawass recalls the painful moment: "The Sphinx for me is like my baby, so that moment, when I came and looked at the Sphinx, I felt like crying. I felt that the Sphinx was also crying. It was telling me that everyone who had come here to restore had made big mistakes."

Among the mistakes were extensive repairs in both the 1920s and the 1980s with modern cement and gypsum mortar, which generated cracks and stresses within the statue's relatively soft limestone. Over the next decade, Hawass supervised an ambitious campaign to remove the cement and gypsum and reverse the damage. His team experimented with many different "recipes" for a protective mortar that they could safely use to repair and consolidate the statue, ultimately settling on a mixture of quicklime and sand. The successful end of the campaign was marked by a symphony concert at the Sphinx in 1998 attended by President Mubarak.

A model for the future

The celebration turned out to be premature. In 2007, new reports that the Sphinx was disintegrating hit the headlines. Sewage was being dumped in a nearby canal, raising concerns that polluted local groundwater was rising under the statue. As moisture creeps up through the porous limestone, it dissolves natural salts in the rock, which expand and crystallize when they reach the surface. This process attacks the weak middle layers of the Sphinx's body, causing the limestone to crumble and in some cases areas break away in big flakes, sometimes with an audible pop. A similar natural process during the Old Kingdom, when the climate was wetter than today, probably began breaking down the Sphinx's body soon after it was carved.

"The Sphinx is not really for Egypt only. It is for everyone."

So Hawass swung into action again, first launching a new effort to map the Sphinx with unprecedented precision. Under the direction of Dr. Walaa Sheta from Egypt's Mubarak City for Science and Technology, state-of-the-art laser ranging gear was hauled to the top of a 150-foot fire-truck ladder to trace the statue's back. From this lofty perch, the gear could map individual rocks on the back to within half an inch.

The result, completed in the spring of 2009, is a precise 3-D model of the statue that future restorers can consult on a computer to check for signs of damage or stress. This "beautifully accurate rendering of the Sphinx," says Hawass, "showing every piece of stone and recording the statue in three dimensions for the first time ... could be very important for conservation, because after doing the laser scanning, you can know what's new on the Sphinx and what should be restored. It's a record for the future."

Constant care

Meanwhile, to stop the groundwater threat, Hawass ordered the drilling of a series of test holes into the bedrock around the Sphinx. These revealed that the water table was 15 feet beneath the statue, posing a long-term threat of rising damp. So pumps were installed close to the Sphinx, and the source of groundwater from the local canal was diverted.

Commenting to NOVA about this latest success, Hawass says, "I think the main message that people should know is that the Sphinx is safe, and that we are like good physicians trying to look after it all the time. I really believe that it keeps all the secrets of our past, and if you ruin that, you will never have a future. And this is why I think that maybe God brought me to be the guardian of the Sphinx to save it for everyone. The Sphinx is not really for Egypt only. It is for everyone. And this is why, even when people see the Sphinx from far away, they can feel that magic."

Further Reading

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"I think the main message that people should know is that the Sphinx is safe," says Dr. Zahi Hawass, Secretary General of Egypt's Supreme Council of Antiquities, seen here before the Sphinx in 2009. Mark Bussell/Providence Pictures

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A member of the Egyptian laser-scanning team at work Mark Bussell/Providence Pictures

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A crew pumps water from beneath the Sphinx, summer 2009 Courtesy Mark Lehner

Evan Hadingham is NOVA's senior science editor.

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