Unlike the mysterious pyramids that continue to inspire intrigue, the Great Sphinx of Giza has mostly avoided debates about its creation. Though researchers have argued who had the statue built or what it was meant to represent, there’s been general consensus on how it was conceived: carved from a single piece of limestone. But what if this isn’t the full story? “Our findings offer a possible ‘origin story’ for how sphinx-like formations can come about from erosion,” Leif Ristroph, an associate professor at New York University’s Courant Institute of Mathematical Sciences, said in a statement. This revelation comes as Cairo's Grand Egyptian Museum, a billion dollar endeavour to preserve, reframe and reclaim Egypt's history, inches towards its inauguration.
In a recently completed paper, which has been accepted for publication in the journal Physical Review Fluids, Ristroph and his colleagues propose that the Great Sphinx could have started as a yardang, a specific type of rock formation. As Smithsonian Magazine points out, the name may sound a bit like maritime jargon, but the concept has nothing to do with the sea. In fact, it’s the near opposite. Yardangs form in desert areas when consistent wind slowly erodes what typically starts as a flat surface. The steady air “chips away” softer material, leaving behind harder rock in an elongated, often fluted shape. This phenomenon happens as far away as Mars, but is also seen much closer to home in places like the Mohave Desert, the Namibian Desert, and – of course – the Sahara Desert, where the Sphinx is located.
Yardangs can form in various shapes and sizes, and some have even been said to look a bit like animals and even people. So it’s not outside of the realm of possibility to wonder if one could form in the shape of a sphinx. To test the theory, NYU scientists recreated the conditions that would’ve been present in Egypt when the statue was built – about 4,500 years ago. The team started with mounds of soft clay embedded with harder, less erodible material inside. They used a steady stream of water to simulate wind, which slowly reshaped the clay into a familiar form: one that looks a bit like a reclining lion. The harder rock became the head, while other features such as “paws,” a “neck” and “curved back” emerged. While the evidence offers an account of the overall form of the statue, the entire sculpture wasn’t an act of pure natural coincidence.
“Our study does not at all go against the view that the bulk of the Sphinx was formed from a single piece of bedrock that is native to that location,” Ristroph tells AD. “While a monolithic or single-rock structure, our view is that the rock is not uniform in its composition, that is some parts are harder or less erodible than others. We think this is a key factor in making a base that resembles a lying lion.” The study shows that while the general shape of the animal could have formed naturally, ancient Egyptians likely carved the more intricate details – including the face – from the yardang.
Ristroph and his colleagues are not the first to postulate a yardang as the genesis of the Great Sphinx. In 1981, geologist Farouk El-Baz proposed a similar theory in a Smithsonian Magazine. The work from Courant researchers offers experiment-based evidence that his theories could be true. “Our work proposes a simple picture for how [yardangs] might form, and we were able to test and confirm the hypothesis in lab experiments,” Ristroph adds. “I find this thrilling, that we can bring such questions into the lab where we can ‘replay’ over hours what takes eons to happen in nature. And that these experiments can perhaps give a little insight about such a cultural icon as the Sphinx is a beautiful bonus.”
While the iconic artwork’s origin may be more clear, there are, of course, still many mysteries about the Great Sphinx. Who is the face is on the statue – most believe King Khafre, though some say Khufu. What was it originally called? And perhaps most notably, what ever happened to its nose?
