Many mysteries still surround the Great Sphinx of Giza. Half-man and half-lion, the colossal statue was created around 2500 B.C.E for the pharaoh Khafre, the builder of the Second Pyramid at Giza.
But what was the terrain the Ancient Egyptians came across when they began to build the Sphinxâand did these natural surroundings have a hand in its formation?
To address these questions a team of New York University scientists replicated conditions that existed 4,500 years agoâwhen the Sphinx was builtâto show how wind moved against rock formations in possibly first shaping one of the most recognizable statues in the world.
“Our findings offer a possible ‘origin story’ for how Sphinx-like formations can come about from erosion,” explains Leif Ristroph, an associate professor at New York University’s Courant Institute of Mathematical Sciences and the senior author of the study.
To do so, Ristroph and his colleagues in NYU’s Applied Mathematics Laboratory took mounds of soft clay with harder, less erodible material embedded insideâmimicking the Mokkatam Formation, a succession of hard and soft sediment layers covering the Giza Plateau.
They then washed these formations with a fast-flowing stream of waterâto replicate windâthat carved and reshaped them, eventually reaching a Sphinx-like formation.
âThe unexpected shapes come from how the flows are diverted around the harder or less-erodible parts,â Ristroph explains.
The harder or more resistant material became the “head” of the lion and many other featuresâsuch as an undercut “neck,” “paws” laid out in front on the ground, and arched “back”âdeveloped as the softer material was quickly removed by the diverted flow.
“Our results provide a simple origin theory for how Sphinx-like formations can come about from erosion,” concludes Ristroph. “There are, in fact, yardangs in existence today that look like seated or lying animals, lending support to our conclusions.”
Yardangs, meaning “steep bank” in the Turkic language of Central Asia, are landscape features found mostly in desert areas. They form as wind picks up dust and mineral grains, “sandblasting” the base of any rock formation in its way.
The study “Sculpting the Sphinx” was accepted to be published in the journal Physical Review Fluids (2023). Additional material and interviews provided by New York University.