The discovery originated half a century ago in the work of a neglected French scholar, R.A. Schwaller de Lubicz (1891-1962). Between 1937 and 1952, Schwaller undertook a survey of the Egyptian Temple of Luxor. His measurements of the floorplan and other detailed observations of the ruins disclosed geometrical relationships not previously suspected. These were confirmed by French archaeologists. Schwaller found similar relationships at other sites. He reported his findings in 1949 and gave a fuller account in 1957. A reviewer for the Journal of Near Eastern Studies urged his colleagues to pay serious attention to Schwaller's work, which challenged the notion of Egypt's mathematical inferiority and suggested a new dimension to Egyptian religious belief. But Schwaller stirred up opposition by the speculative meanings that he assigned to Egyptian architecture and inscriptions, and other scholars dismissed his findings.
Schwaller observed a curious physical anomaly in the pyramid complex at Giza. The erosion on the Sphinx, he noted, was quite different from the erosion observable on other structures. Schwaller suggested that the cause of erosion on the Sphinx was water rather than wind-borne sand. At the time, nobody understood the implications of this observation and it went largely unnoticed until the 1970s, when the independent Egyptologist John Anthony West took up the question.
What is now the Sphinx head was probably at one time an outcrop of rock. The 240-foot body of the monument, in the shape of a recumbent lion facing east, was excavated from the limestone bedrock of the Giza plateau, forming an open enclosure around it. A small temple, the "Sphinx Temple," stands in front of the monument. This and an adjacent temple to the south, known as the "Khafra Valley Temple," originally stood close to the Nile river. The Valley Temple is at one end of a long 1600 foot causeway that leads to the Mortuary Temple in front of the Pyramid of Khafra (Chephren). The Sphinx and Valley Temples consist of huge limestone blocks quarried from the enclosure and refaced with Aswan granite. To the northeast of Khafra's pyramid lies the Great Pyramid of Khufu (Cheops) and to the southwest lies the Pyramid of Menkaura (Mycerinus). Causeways also link the Khufu and Menkaura pyramids to valley temples along the ancient Nile. Archaeologists attribute the Sphinx to the Old Kingdom fourth dynasty ruler Khafra, who reigned from 2520-2494 BCE.
West compared the erosion on the Sphinx, on its temples, and on the enclosure walls to the erosion of other structures on the Giza plateau. On the Sphinx and its nearby walls, the rock was worn badly, giving it a sagging appearance. Edges were rounded and deep fissures were prominent. On structures elsewhere on the plateau, the surfaces showed only the sharper abrasion of wind and sand. Egypt experienced periods of heavy rainfall in the millennia that marked the post-glacial northward shift of the temperate zone. This period lasted from about 10,000 to 5000 BCE and by its end the Sahara had turned from green savanna into a desert. A shorter but more intense period of rainfall lasted from about 4000 to 3000 BCE, tapering off by the middle of the third millennium. West thought that flooding from the post-glacial transition caused the distinctive weathering on the Sphinx complex, which meant that the Sphinx must have been carved during or before the transition. Orthodox archaeologists refused even to consider West's hypothesis. But in 1990 West persuaded Robert M. Schoch, a geologist at Boston University, to examine the question. Curious, Schoch agreed and the two visited Giza in June 1990.
Archaeologists agreed that the Sphinx complex stood close to earlier flood levels and that flooding probably reached the base of the Sphinx on occasion. However, flood levels have declined since Old Kingdom times. Schoch observed that erosion was heaviest on the upper parts of the Sphinx and enclosure walls, not around the base, where flooding should have undercut the monument. This upper surface weathering was typical of damage by rainfall, as were the undulating impaction pattern and fissures on the Sphinx and nearby walls. Schoch noticed that the limestone blocks on the Sphinx and Khafra Valley Temples were similarly eroded and that some of the refacing stones appeared to have been form-fitted to the eroded blocks behind them. Inscriptions suggest that the refacing stones dated from the Old Kingdom, which suggested that the original walls eroded long before.
On a second trip to Giza in April 1991, West and Schoch brought Thomas Dobecki, a geophysicist from Houston, Texas, to carry out a seismic survey of the enclosure foundations to determine whether the underlying rock showed evidence of precipitation damage. The degree of subsurface weathering could be measured by bouncing sound waves off of deeper layers of rock. With the permission of the Egyptian Antiquities Organization, the team carried out sound-wave tests through the floor of the enclosure.
Schoch and Dobecki discovered that the enclosure floor in front and alongside of the Sphinx had weathered to a depth of six to eight feet. They also discovered that the back of the enclosure had weathered only half as far. Schoch agreed that the floor behind the Sphinx had been excavated during the Old Kingdom but he concluded that the sides and front of the monument were twice as old. Assuming a linear rate of weathering, Schoch estimated the date of the Sphinx and most of the enclosure to between 5000 and 7000 BCE, far earlier than the date of 2500 assumed by archaeology. Schoch noted that weathering could have been non-linear, slowing as it got deeper because of the increasing mass of rock overhead. On this assumption, the Sphinx could have been significantly older than 7000 BCE.
Egyptologists dated the Sphinx to Khafra from several kinds of evidence. A stela from the New Kingdom reign of Thutmose IV (1401-1391 BCE) stands in front of the monument, and an inscription that has since flaked off contained the first syllable of Khafra's name. Statues of Khafra found in his Valley Temple also seemed to associate the complex with Khafra, and the Sphinx head was assumed to be his as well. Finally, the causeway from Khafra's pyramid was built into the Khafra Valley Temple.
There was some uncertainty about the date even before West opened the question. Egyptologists agree that repair work to fill in fissures or to protect corroded areas on the monument took place in the New Kingdom no later than about 1400 BCE. This gave little over a millennium for the erosion on the Sphinx to have reached such proportions as to require protective mortaring and partial covering. During much of this time, the main body of the Sphinx was probably buried in sand. The other evidence linking Khafra to the complex was circumstantial. The syllable khaf, for example, could have had other meanings.
West disproved one piece of supposed evidence. With the help of a New York City police artist, Detective Sgt. Frank Domingo, West compared the head of the Sphinx with a known head of Khafra. Sergeant Domingo generated profiles of the two heads by computer and by hand and found a very different facial structure in the profile of the Sphinx compared to the profile of Khafra. The difference is easily seen in photographs of the two heads.
West and Schoch presented their evidence with considerable trepidation before the Geological Society of America meeting in San Diego on October 23, 1991. Instead of finding some obvious flaw in their results, a number of geologists offered their support. In newspaper interviews and private correspondence, however, other geologists raised two objections. One asked if the seismic refraction data coincided with a natural fluctuation in the rock layer itself. In fact, the seismic profile did not follow the natural dip of the rock. Another geologist proposed that the entire Sphinx , and not just the head, was a natural outcrop of rock. Such an outcrop, known in geology as a "yardang," could have eroded for millennia before being carved. But the Sphinx body and nearby temple blocks matched the stratification pattern of the excavated bedrock. They had clearly been carved out of the plateau along with the enclosure floor. Only the head could have been an outcrop. Schoch believed that the head, which was too small in proportion to the body, had probably been recarved in historic times from an earlier lion's head. As publicity for the findings began to appear, some archaeologists denied the possibility of an earlier date. "There's just no way that could be true," countered one scholar, who pointed to the absence of known government and civilization from the earlier period. "There are no big surprises in store for us," declared another scholar.
The American Association for the Advancement of Science scheduled a session to debate the issue at its annual meeting in Chicago on February 7, 1992. A leading authority on the Sphinx, Mark Lehner, director of the American Research Center in Cairo, defended an Old Kingdom date for the Sphinx. He was joined by a geologist, K. Lal Gauri of the University of Louisville, who had studied the Sphinx for a decade. Robert Schoch and Thomas Dobecki defended their results suggesting an earlier date.
After reviewing the standard reasons for dating the Sphinx to Khafra, Lehner asked the basic question raised by his colleagues in archaeology: where was the civilization that had to have existed to carve the Sphinx and build the temples so many millennia before the Old Kingdom? Archaeology had found no evidence of civilization in Egypt that far back. The Egyptians of the post-glacial transition were primitive "hunters and gatherers" who could not have built such a monument.
Gauri circulated a short paper that attributed the erosion on the Sphinx primarily to geochemical effects associated with either an upward seepage of groundwater or with atmospheric condensation and evaporation, which occurred even in the dry climate of the area. But in his own paper, Schoch addressed this objection. Until recently, the water table lay too far below the enclosure floor to be a serious factor. There was evidence of condensation damage to the Sphinx and its temples, but such damage was common to all of the structures on the Giza plateau and was in his view the least serious kind of weathering. It could not account for the nature and severity of the impaction patterns on the Sphinx and its temples.
To the problem of archaeological context for an earlier Sphinx, Schoch replied that urban centers had existed in the eastern Mediterranean at Catal Huyuk from the seventh millennium and at Jericho from the ninth millennium BCE. At Jericho there were large stone walls and a thirty foot tower. No such settlement had been found in Egypt itself but clearly there was civilization in the region. More evidence could be under millennia of Nile river silt.  An advanced civilization may not have been necessary. A Neolithic culture was able to erect Stonehenge in Britain.
The AAAS meeting broke up in words that, according to The New York Times, "skated on the icy edge of scientific politeness." A writer for the AAAS magazine Science wrote that Schoch "hadn't convinced many archaeologists or geologists" of his findings. In fact, Schoch had received offers of support from geologists after the October and February meetings. Even some archaeologists accepted his geological findings without conceding the conclusion to which they pointed. West spent the next eighteen months producing a documentary for television that attracted thirty million viewers when it aired in the United States on November 10, 1993.
The Giza monuments have long been a subject of mystery and speculation. Arabs called the Great Sphinx the "Father of Terrors," while many Western writers have seen in the Pyramids everything from tombs to secret wisdom. John Anthony West has suggested that an ice age date for the Sphinx raises anew the question of a lost ice age civilization, possibly the Atlantis of ancient legend. The evidence dating the Sphinx to an earlier time does not prove such legends. But if the hypothesis of rainfall erosion is true, it does call the known chronology of African and indeed world civilization into question.
The evidence for an earlier Sphinx raises additional questions: If the Sphinx complex is so much older, who built it and why? Should we be more tentative in what we assume about the first half of the last ten thousand years? If so, how should that affect what we know about the second half? Some answers may be forthcoming in the next few years as the new findings are examined and tested. Until then, the Sphinx challenges us to rethink our history and keep an open mind.
l. R.A. Schwaller de Lubicz, Le Temple dans l'Homme (Cairo, 1949) and Le Temple de l'Homme (Paris, 1957). Schwaller's stepdaughter, Lucie Lamy, conducted the measurements at Luxor.
2. Review by Bernard V. Bothmer of R.A. Schwaller de Lubicz, Le Temple dans l'Homme in the Journal of Near Eastern Studies, Vol. 9, No. 2 (April 1952), pp. 151-152.
3. John Anthony West presented Schwaller's work and raised the question of the Sphinx's erosion in Serpent in the Sky: The High Wisdom of Ancient Egypt (New York, 1978; Wheaton , Illinois, 1993).
4. For an overview of the Giza monuments, see I.E.S. Edwards, The Pyramids of Egypt (New York and London, 1961, 1985).
5. On the holocene climate history of Egypt, see R. Said (ed) The Geology of Egypt (Rotterdam, 1990), pp. 487-507.
6. West, Serpent in the Sky (1993), pp. 186-189.
7. On flood levels in ancient Egypt, see Karl W. Butzer, Early Hydraulic Civilization in Egypt: A Study in Cultural Ecology (Chicago and London, 1976), pp. 27-28.
8. Schoch's preliminary report was Robert M. Schoch, "How Old is the Sphinx? A Draft Status Report as of 10 January 1992, " sent by Schoch to this author, 28 January 1992. A published version appeared as Robert M. Schoch, "Redating the Great Sphinx of Giza," KMT: A Modern Journal of Ancient Egypt, Vol. 3, No. 2 (Summer 1992), pp. 52-59, 66-70.
9. For the seismic results, see Schoch, "How Old is the Sphinx?" pp. 17-19, and Thomas L. Dobecki and Robert M. Schoch, "Seismic Investigations in the Vicinity of the Great Sphinx of Giza, Egypt," Geoarchaeology, Vol. 7, No. 6 (1992), pp. 527-544.
10. Selim Hassan, The Sphinx: Its History in the Light of Recent Excavations (Cairo, 1949), pp. 88-91 still provides the best summary of the evidence for a Khafre attribution. Hassan cautions that the evidence is circumstantial.
11. For the history of repair work on the Sphinx, see Mark E. Lehner, "The ARCE Sphinx Project: A Preliminary Report," American Research Center in Egypt Newsletter, No. 112 (1980), pp. 3-33.
12. For Sgt. Domingo's findings, see West, Serpent in the Sky (1993), pp. 230-232. For photographs of the two heads, see John Anthony West, The Traveler's Key to Ancient Egypt: A Guide to the Sacred Places of Ancient Egypt (New York, 1985), pp. 148-149.
13. For an abstract of their presentation, see R.M. Schoch and J.A. West, "Redating the Great Sphinx of Giza, Egypt," Annual Meeting, Geological Society of America, Vol. 23, No. 5 (1991), p. A253.
14. See Schoch, "How Old is the Sphinx?" p. 37-38.
15. See the comments of Farouk El-Baz of Boston University and Schoch's reply in Boston University Today, 11-17 November 1991, p. 7.
16. See the The Los Angeles Times, 23 October 1991, p. A18.
17. See the The Boston Globe, 23 October 1991, p. 8.
18. Topical Debate: "How Old is the Sphinx?" Abstracts of Papers, 1992 AAAS Annual Meeting (Washington, 1992), p. 202. The New York Times, 9 February 1992, p.34. "Sphinx Riddle Put to Rest?" Science, Vol. 255, No. 5046, 14 February 1992, p. 793.
19. The New York Times, 9 February 1992, p. 34.
20. Abstracts of Papers, 1992 AAAS Annual Meeting, p. 202.
21. Schoch, "How Old is the Sphinx?" pp. 6-10.
22. For Catal Huyuk, see J. Mellaart, Catal Huyuk: A Neolithic Town in Anatolia (London, 1967), and for Jericho, see Dame Katherine Kenyon, Archaeology in the Holy Land, 4th ed. (London and New York, 1979). For an overview of late prehistoric Egyptian settlement, see William C. Hayes, Most Ancient Egypt, ed. Keith C. Seele (Chicago and London, 1964-65).
23. Abstracts of Papers, 1992 AAAS Annual Meeting, p. 202.
24. For a reconstruction of how Stonehenge could have been built, see R.J.C. Atkinson, Stonehenge (London, 1956), pp. 125-135.
25. The New York Times, 9 February 1992, p. 34.
26. "Sphinx Riddle Put to Rest?" Science, Vol. 255, No. 5046, 14 February 1992, p. 793. The article reports that radioisotope dating of the Sphinx is not possible. In fact, radioisotope analysis of surface interactions with cosmic radiation, a new technique, would date the current rock's exposure to the sky. It would not give the exposure date of the original rock because the original surface has probably weathered away, but it would provide an absolute minimum date. The Egyptian Government has not permitted the taking of samples from the Sphinx for radioisotope dating.
27. See the remarks of Lanny Bell of the University of Chicago in The Boston Globe, 23 October 1991, p. 8, and John Baines of Oxford University in The Independent [London], 14 October 1991, p. 17.
28. Broadcast on the NBC network at 9:00 PM EST. The documentary won a 1993 Emmy Award for Best Research and a nomination for Best Documentary.
29. For a survey of speculation about the Giza monuments, see Peter Tompkins, Secrets of the Great Pyramid (Harper and Row, New York, 1971).
30. See West, Serpent in the Sky (1993), pp. 215-220.