Sphinx water erosion hypothesis

The Sphinx water erosion hypothesis contends that the main type of weathering evident on the enclosure walls of the Great Sphinx was caused by prolonged and extensive rainfall that would have predated the time of Djedefre and Khafre, the Pharaohs credited by most modern Egyptologists with building the Great Sphinx and Second Pyramid at Giza around 2500 BC. Egyptologists, geologists and others have rejected the water erosion hypothesis and the idea of an older Sphinx, offering various alternative explanations for the cause and date of the erosion.

R. A. Schwaller de Lubicz, a French mystic and alternative Egyptologist, first claimed evidence of water erosion on the walls of the Sphinx enclosure in the 1950s.John Anthony West, an author and alternative Egyptologist, investigated Schwaller de Lubicz's ideas further and, in 1989, sought the opinion of Robert M. Schoch, a geologist and associate professor of natural science at the College of General Studies at Boston University.

From his investigation of the enclosure's geology, Schoch concluded the main type of weathering evident on the Sphinx enclosure walls was caused by prolonged and extensive rainfall. According to Schoch, the area has experienced a mean annual rainfall of approximately one inch (2.5 cm) since the Old Kingdom (c. 2686 – 2134 BC), such that, since Egypt's last period of significant rainfall ended between the late fourth and early 3rd millennium BC, the Sphinx's construction must date to the 6th or 5th millennium BC.

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