The Great Sphinx of Giza might have been sculpted by desert winds long before humans carved into it.
Mysterious natural desert structures called yardangs look a lot like seated lions. Some researchers now think the ancient Egyptians might have carved the Great Sphinx out of one.
Built around 4,500 years ago, this massive statue sports the head of a woman and body of a lion. A new study shows that this general shape forms under fairly simple natural conditions — no people needed. Scientists were able to shape their own sphinxlike mini-yardangs from clay globs immersed in flowing water.
“This just came completely out of left field,” says Elena Favaro, who did not take part in the new study. She works at the Open University in Milton Keynes, England. There, Favaro studies how forces such as ice, wind and water can shape Earth’s surface.
Yardangs can evolve naturally in desert regions where winds wear exposed rock into long, streamlined ridges. But scientists aren’t sure what triggers yardangs to form. The new study, Favaro says, is “a very inspired way” to approach answering the question.
Researchers at New York University (NYU) reported their new findings November 16 in Physical Review Fluids.
Leif Ristroph was curious about how nature produces sphinxlike yardangs. This applied mathematician and his team at NYU’s mathematics college study how natural features form and change. Ristroph designs experiments that mimic the erosion of rock by natural forces (such as wind, water and ice). In nature, erosion often occurs over thousands of years or more. To study it in the lab, Ristroph’s team sped up the process. Using a water tunnel, their method takes only a few hours. The tunnel uses water currents to study how air or other fluids flow around stiff objects, such as wings.
“[We can] put things like a piece of ice in there and look how it changes shape,” Ristroph says. Or, “in this case, a chunk of mud.” His team…
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