The Official Website of Robert M. Schoch
GEOLOGICAL EVIDENCE PERTAINING TO
THE AGE OF THE GREAT SPHINX
This article was written in 1999-2000 and published in slightly modified form in 2002/2003, In Emilio Spedicato and Adalberto Notarpietro, editors, New Scenarios on the Evolution of the Solar System and Consequences on History of Earth and Man, Proceedings of the Conference, Milano and
by Dr. Robert M. Schoch © 1999-2000
ABSTRACT
Many recent Egyptologists have attributed the carving of the Great Sphinx of Giza to the Old Kingdom Pharaoh Khafre (Chephren), ca. 2500 B.C. However, on the basis of a number of lines of geological, seismological, Egyptological, and related evidence, I have come to the conclusion that the structure commonly known as the Great Sphinx was built in stages (originally it may not have even been a Sphinx). Initial carving of the core body of the Sphinx is estimated to have taken place during the period of approximately 7,000 to 5,000 B.C. The Sphinx has subsequently been reworked and refurbished many times over the succeeding millennia -- including, probably, during the reign of Khafre. In particular, the rump or rear of the Sphinx was carved out or recarved much later than the core body, and the head of the Sphinx has been recarved.
My geological work suggests that Khafre merely restored the Sphinx. The body of the Sphinx, carved from the local bedrock and thus sitting in the bottom of an artificial hollow (ditch or enclosure), and the walls of the Sphinx enclosure exhibit well-developed precipitation-induced (rainfall runoff) weathering, erosion, and degradation (characterized by a rolling and undulating vertical profile) not typically seen on Old Kingdom Giza Plateau structures (which exhibit primarily wind-induced weathering marked by a more angular profile with soft layers removed by wind abrasion) also excavated from the Mokattam limestone. This deep precipitation-induced weathering of the Sphinx is interpreted as predating the current arid regime of the area, and thus indicates that the body of the Sphinx predates
The so-called
INTRODUCTION
The Great Sphinx, carved out of limestones of the Eocene Mokattam Formation, standing 66 feet (20 meters) high and 240 feet (73 meters) long, sits on the edge of the Giza Plateau (just west of Cairo, Egypt) east of the three great pyramids. Most recent Egyptologists have attributed the carving of the Great Sphinx to the time of the Old Kingdom Fourth Dynasty Pharaoh Khafre (Chephren), approximately 2500 B.C. by various standard chronologies. In addition the so-called
For many years the independent Egyptologist John Anthony West (see West, 1979, 1987, 1989, 1993a), based on the work of the late R. A. Schwaller de Lubicz (see Schwaller, 1982), has promulgated an interesting hypothesis: that the Great Sphinx of Giza may be older than its traditional attribution. Primarily on the basis of weathering and erosional features seen on the Great Sphinx and its associated temples, as compared to weathering seen on other structures attributed to the Fourth Dynasty, West suggested that the Sphinx may predate the Fourth Dynasty. West contacted me concerning his hypothesis in 1989, and although I was extremely skeptical of his ideas I did agree to look into it from a geological perspective. Beginning during the summer of 1990 West and I began to research this problem in earnest, including several expeditions to Egypt specifically to look at the evidence bearing on the age of the Great Sphinx (see Schoch, 1992a, 1992b, 1992c, 1992d, 1992e, 1993a, 1993b, 1994a, 1994b, 1995a, 1995b, 2000; Schoch with McNally, 1999, 2000; Schoch and West, 1991; West, 1993a, 1993b; see also Moore, 1992, and Payn, 1992).
SUMMARY OF GEOLOGICAL AND FIELD EVIDENCE
BEARING ON THE AGE OF THE SPHINX
Major geological and field evidence bearing on the age of the Great Sphinx is summarized in this section. I have divided this evidence into four main categories:
1) Weathering Patterns, 2) Two-Stage Construction of the Sphinx and
Weathering Patterns
Modifications to rock surfaces, such as those resulting from weathering, erosion, and paleosol development, have long been utilized as criteria in determining the relative times since fresh rock surfaces were first exposed to the elements (see, for example, Brookes, 1985; Coates, 1984; Evans, 1985; Finkl, 1984; and Vreeken, 1984). Such methodologies have been widely used to date Quaternary land surfaces in particular, but the same concepts can also be applied to other dating problems -- such as the age of the initial carving of the Sphinx relative to other cultural features found on the Giza Plateau.
There appear to be four distinct forms or modes of weathering and erosion
(degradation) exhibited on the Giza Plateau.
1) Precipitation-induced weathering and erosion is seen on the body of the Sphinx and in the ditch or hollow surrounding the Great Sphinx. This gives a rolling and undulating vertical profile to the weathered rocks, and is very well-developed and prominent within the Sphinx enclosure. The rocks that display this mode of weathering also often contain prominent vertical crevices and other solution features, as well as cross-cutting diffusion fronts (see El Aref and Refai, 1987 [discussed further below], who thoroughly describe these features; see also Issawi, 1992, p. 17, who notes that "in parts of the statue [the Sphinx], the limestone is highly porous and cavernous showing evidences of being greatly affected by water erosion."). Many of the vertical and inclined solution features follow joints and faults in the bedrock.
2) Wind-induced weathering and erosional features are seen on structures that are attributed unambiguously to
3) Present on the body of the Sphinx, as well as on other structures (and essentially forming an overlay on many precipitation-induced and wind-induced megascopic weathering features), are weathering features that are interpreted as the result of relatively recent (within the last couple of centuries) efflorescing of dissolved and recrystallized minerals (such as halite) on the surface of the rock which have subsequently flaked off and deteriorated the stone. It has been suggested that subsurface moisture migrating up into the Sphinx and the surrounding rocks may account for much of this activity (see Gauri and Holdren, 1981). Alternatively, or complementarily to the migration of subsurface groundwater, similar weathering is actively taking place during the present day due to the condensation of atmospheric moisture on the rock. As described by Gauri, Chowdhury, Kulshreshtha, and Punuru (1988, pp. 725-726), "the moisture is able to condense as droplets of water in the cool of the night. This moisture forms concentrated salt solution, a process augmented by the hygroscopicity of the existing halite. The salt solution enters the pores under the influence of capillary force. At sunrise, as the water begins to evaporate, crystals of salt grow producing crystallization pressure. Often one can hear in the morning the sound of popping stone resulting from pressures produced under the surface layers."
Gauri, Holdren, and Vaughan (1986) have suggested that much of the deterioration of the Sphinx is due to the migration of salts under the influence of water originating from the atmosphere. These authors (Gauri et al., 1986, pp. 4-5) state: "Burial of the Sphinx for centuries under the desert sand has, it appears, resulted in the migration of salts from the depth of the bedrock toward the surface. The authors deduced this phenomenon from observations made in the process of mapping the Sphinx geologically [Gauri, 1984], when sand was removed that had piled up in recent times against the rock surfaces bounding the ditch around the Sphinx. Even though the sand appeared dry at the surface, it was completely soaked with water a few inches below the surface. Also, the bedrock in contact with the sand was soaked with water. The source of this water is the atmosphere, and not the subsurface, because the water table lies many meters below the surfaces under consideration. Therefore, during the long burial of the Sphinx, the rock must have become wet to a considerable depth, and as it dried when exposed to the sun, the salts must have become concentrated in the surface layers."
As is pointed out later in this paper (see section on "Ancient Repair Campaigns to the Body of the Sphinx"), the vast majority of the weathering and erosion occurred to the Sphinx prior to circa 1400 B.C. In places the walls of the Sphinx enclosure exhibit over a meter (3.3 feet) of erosion, and in places perhaps over two meters (6.5 feet) of erosion (see, for instance, the profile in Gauri, 1984, p. 32). It is hard to imagine that the mechanism of migrating salts, described in the last paragraph (quoted from Gauri et al., 1986), could be solely responsible for producing these deep weathering features in the time span from 2500 B.C. (when Khafre presumably had the Sphinx carved) to 1400 B.C. It is particularly difficult to reconcile Gauri et al.'s (1986) proposed weathering mechanism with the observed surficial morphology of the rocks in consideration of the following points: 1) As is described below, the Sphinx enclosure may have been buried in sand for at least half of the period between 2500 B.C. and 1400 B.C.; 2) the weathering patterns seen on the body of the Sphinx and the walls of the Sphinx enclosure clearly exhibit features associated with precipitation-induced weathering (cf. El Aref and Refai, 1987); and 3) as has already been pointed out, Old Kingdom tombs and other structures on the Giza Plateau that were carved from the same member of the Mokattam Formation do not exhibit the same weathering features to the degree seen on the body of the Sphinx and the walls of the Sphinx enclosure. If Gauri et al.'s (1986) mechanism of migrating salts since 2500 B.C. was the primary agent responsible for the weathering and erosional features seen on the body of the Sphinx and on the walls of the Sphinx enclosure, then one should expect to observe weathering and erosional features of a similar nature and degree on the Old Kingdom tombs and other structures that are carved out of the same sequence of limestones as the body of the Sphinx.
4) Weathering due to the dissolution and recrystallization of calcite and other minerals in the rocks is visible within various tombs and chambers cut into the bedrock of the Giza Plateau. This may occur on a daily basis as water condenses on the cool surfaces of these man-made caves, and subsequently evaporates once again as the temperature rises; this gives the surface of the rock, and any carvings it may bear, almost the appearance of slightly melted wax, at times covered with a very fine coat of mineral crystals. This is the most minor component of weathering observed on the Giza Plateau. It is preserved in only a limited number of tombs and other artificial cave-like structures, such as tombs directly north of the Sphinx on the eastern edge of the Giza Plateau.
Of the four modes of weathering listed above, some rocks may show one mode of weathering overlain by another -- thus in particular cases the various modes of weathering may be somewhat difficult to sort out. On the whole, however, they are clear and distinct from one another on the Giza Plateau.
What is interpreted as precipitation-induced weathering and erosion (#1, above) is the oldest predominant mode of weathering identified on the Giza Plateau. It is found only on the oldest structures of the Giza Plateau to any significant degree, such as the body of the Sphinx and the walls of the Sphinx enclosure. Of course it still rains on the Giza Plateau occasionally, and thus precipitation-induced weathering can be said to be found on all Giza Plateau structures to some small degree; here we are talking in generalities and attempting to look at the broad picture. In many places this precipitation-induced mode of weathering has superimposed upon it wind-induced weathering (#2, above). Presumably the major portion of this precipitation-induced weathering occurred prior to the onset of the current arid regime exhibited on the Giza Plateau (i.e., prior to the modern climatic regime of the
The other two modes of weathering noted above (#3, efflorescing of dissolved and recrystallized minerals, and #4, dissolution and recrystallization of calcite) appear to be, on the whole, phenomena that have been significant only recently. In the 1960s the Aswan High Dam was built, and this, along with the accompanying intense agriculture and the generally burgeoning population of
Intensified irrigation and the maintenance of the water level in the Nile have afflicted
As they say in
All of these detrimental effects of rising water tables are currently exhibited on the body of the Sphinx, and around the area of the Giza Plateau generally. Other researchers have focused attention on these modes of weathering relative to the Sphinx, particularly the damage currently being done by mobilized salts (see for instance the work by Gauri and Holdren, 1981; Chowdhury et al., 1990; Punuru et al., 1990; Gauri and Punuru, 1989; Gauri et al, 1986; Gauri et al., 1988; Gauri, 1992; see also the article by Brock, 1990). These studies are of extreme importance in attempting to halt the current destruction of the Sphinx (Brookes, 1992; Egyptian Antiquities Organization, 1992; Hedges, 1992). It must be remembered, however, that studies of the weathering agents currently damaging the Great Sphinx may not be of relevance when attempting to determine the genesis of ancient weathering and erosional features on the Sphinx.
In their work on the weathering of the Sphinx Gauri and his colleagues (see references cited above) have suggested that in general the upper beds of the middle member (Member II or Setepet Member) of the core body or thoracic region of the Sphinx are more durable than the lower beds of this member. These workers have calculated durability factors for different beds of this member; such factors range from about 100 (high durability) for the uppermost bed just below the neck of the Sphinx to about 11 for the lowermost bed of the member. There is a general trend of increasing durability factors, as calculated by these authors, going up section. Thus their bed 4i (located approximately halfway up the body of the Sphinx) has a calculated durability factor of 75 (see summary of this work in Gauri et al., 1988).
It is significant to note that on the wall of the Sphinx ditch the beds for which Gauri et al. calculate the highest durability factors are not consistently the least weathered and receded in profile (assuming that the wall of the Sphinx ditch was originally cut vertically or nearly vertically, perhaps at an angle of 80 degrees or so). For instance, utilizing Gauri's own data (Gauri, 1984, p. 32, fig. 3C), in an east-west profile of the rear of the Sphinx and the wall of the Sphinx ditch one sees that beds 1i and 2i, which both have low durability factors of 11, are greatly receded and undercut the overlying units of higher durability (beds 1ii and 2ii). However, in the same section bed 2ii (with a durability factor of 76) is receded further back than is the lower-lying bed 1ii (durability factor of 56). Likewise, bed 3ii (durability factor of 76) is receded further back than the underlying bed 3i (durability factor of 42), and beds 4i and 4ii (durability factors of 75 and 86 respectively) are receded further back than the lower-lying bed 3ii. In general, the amount that a bed has receded is not so much a function of its present-day durability factor, but primarily a function of its geometric position on the exposure. It would be logical that precipitation falling down from above would preferentially weather the uppermost beds and cause them to recede back at a faster rate than the lower beds. Again, this train of thought suggests that the Sphinx and walls of the Sphinx ditch were subjected to precipitation-induced weathering.
There have been a few other previous studies of note concerning weathering and erosion on the Giza Plateau. Emery (1960) and Said and Martin (1964) discussed briefly the weathering to the pyramids, but their work is not directly applicable to the present discussion. More pertinent to the topic at hand, El Aref and Refai (1987) made a comprehensive macroscopic study of paleokarst processes and features on the Giza Plateau, concentrating in particular on the area of the Sphinx enclosure. These authors pointed out many paleokarst features that are attributable to periods of seasonal rainfall. They illustrate and discuss solution holes, solution depressions, solution joints, symmetrical concentric cross-cutting diffusion fronts, and other dissolution features found on the body of the Sphinx and on the walls of the Sphinx ditch. El Aref and Refai (1987, p. 376) note that "The karstic rocks are mantled by soil material and/or surficial calcareous duricrust. The solution features are partially or completely filled with clay precipitates together with concretions of iron and manganese oxides and collapse breccia fragments." (As a side note, these iron and manganese oxides often take on a red or ocher color. Lehner [1991, p. 36] noted that "if you probe any seam in the masonry covering the lower part of the body [of the Sphinx], a red powder appears." This may simply be red earthy/clay material, typical karst sediments that one would expect in such a limestone terrane that has been subjected to weathering via precipitation. Lehner [1991] and Hassan [1949] both suggest that the Sphinx and surroundings were traditionally painted red. This putative red paint, however, may actually consist, in part, of natural weathering products of the rock, although the Sphinx may have been artificially painted red also.) El Aref and Refai conclude (1987, p. 376) that "The development of these karst features and the associated sediments indicate that the study area was subjected to intensive seasonal rainfall and evaporation of temperate (Mediterranean) climatic conditions."
If the Great Sphinx was weathered heavily, and at an early period, by precipitation, this suggests that it may have been carved prior to the last period of major precipitation in this part of
Hayes (1965, p. 23) summarized much of the classical work carried out on reconstructing the climate of this period in Egypt's history when he wrote: "Toward the end of the sixth millennium B.C. Egypt and neighboring lands appear to have enjoyed another slight, but effective increase in temperature and precipitation and to have entered upon a prolonged sub-pluvial or relatively moist phase, extending from early Neolithic times until late in the Old Kingdom (ca. 5000-2350 B.C.). . . . Since the end of the third millennium B.C. the climate of
On the basis of the climatic history outlined above, one might tentatively suggest that the Great Sphinx was built in very early dynastic times or late predynastic times (late fourth millennium or earliest third millennium B.C.). However, one must account for the considerable weathering that appears on the walls of the Sphinx hollow, on the body of the Great Sphinx itself, and on the walls of the Valley and Sphinx Temples (see below) -- in the case of the Great Sphinx and its associated temples, weathering that was possibly covered up or repaired during the Old Kingdom (circa 2600-2400 B.C.). One must also take the seismic data into account (see below). These latter considerations suggest the possibility that the initial carving of the Great Sphinx may be at least several millennia older than its standard attribution.
Two-Stage Construction of the Sphinx and
As far as can be determined, the core of the Sphinx Temple (and possibly the core of the Valley Temple) is constructed out of titanic limestone blocks taken directly from the ditch around the Sphinx (see the work of Aigner, 1982, 1983a, 1983b, 1983c, and Lehner, 1980, 1985a, 1985b, 1991, 1992a, 1992b, 1997). Therefore the limestone core of the
Based on my field observations of the granite ashlars and the underlying limestone blocks, I believe that the limestone core blocks of both the
The general Egyptological community agrees that the granite facing on the Sphinx and
which according to West (personal communication; see also Edwards, 1985; Grinsell,
1947; Hawass, 1990) appears, on stylistic grounds, to be an
It seems a good assumption that the limestone core blocks would have been freshly cut (that is, unweathered) when initially used to construct the temples. Therefore if the granite facing is covering deeply weathered limestone, the original limestone structures must predate by a considerable degree the granite facing. Obviously, if the limestone cores (originating from the Sphinx ditch) of the temples predate the granite ashlars (granite facings), and the granite ashlars are attributable to Khafre of the Fourth Dynasty, then the Great Sphinx was built prior to the reign of Khafre. Note, however, that the attribution of the granite ashlars to the time of Khafre is itself circumstantial. As mentioned above, the ashlars bear Old Kingdom inscriptions and therefore must be at least as old as the
Ancient Repair Campaigns to the Body of the Sphinx
The body of the Sphinx has been subjected to various repair campaigns, beginning with the ancient Egyptians themselves and continuing up to the present day. The earliest repairs to the body of the Sphinx have been carried out using what appear to be
Lehner has analyzed the repair campaigns to the Sphinx (see Lehner, 1980; Hamblin, 1986), concluding that, despite his own evidence to the contrary, "To seek agreement with known historical facts [i.e., his contention, among other things, that the Sphinx was built in circa 2500 B.C. by Khafre], we should probably expect the earliest restoration to have been done in the New Kingdom [circa 1500-1400 B.C.]" (Lehner, 1980, p. 18). In summary, in order to save the attribution of the Sphinx to Khafre (Chephren), circa 2500 B.C., Lehner suggests that the earliest level of "large-block" (Old Kingdom style?) masonry was added to the Sphinx during the
Seismic Surveys of the Sphinx Area
Seismic geophysical surveys (Dobecki, 1992; Dobecki and Schoch, 1992) indicate that the subsurface weathering in the Sphinx enclosure is not uniform. This strongly suggests that the entire Sphinx ditch was not excavated at one time. Furthermore, by estimating when the less weathered portion of the Sphinx enclosure was excavated and thus first exposed subaerially one can tentatively estimate when initial excavation of the Sphinx enclosure may have begun.
During our April 1991 trip to
Nineteen refraction profiles, two reflection profiles, and a refraction tomography data set were collected on the Giza Plateau during April 1991. The seismic work performed around the base of the Sphinx consisted of hitting a sledgehammer on a steel plate, thus generating energy waves that entered the rock, travelled into the subsurface, and reflected and refracted off of subsurface features. In the Sphinx enclosure refraction profiles gave us information on the subsurface weathering of the rock. In addition, we located various voids, cavities, and other subsurface features (see Dobecki and Schoch, 1992).
Analysis of the seismic data collected in April of 1991 contributes further to exploring the age of the Great Sphinx. Seismic lines taken in front of and along the body of the Great Sphinx on either side (east [seismic line S4], north [seismic line S1], and south [seismic line S2] of the Sphinx) indicate that below the surface the limestone is weathered up to six to eight feet [1.8 to 2.5 meters] deep. However, along the back (west side [seismic line S3]) of the Great Sphinx the identical limestone has only been weathered to a depth of approximately four feet [1.2 m]. These results were completely unexpected. It is the same limestone that surrounds the Great Sphinx (the floor of the Sphinx enclosure where all of the seismic lines were taken consists of Gauri's [1984] Rosetau Member, or Member I), and if the entire body of the Great Sphinx was carved out of living rock at one time, it would be expected that the limestone surrounding it should show the same depth of subsurface weathering. One possible interpretation of the data we collected is that initially only the sides and front (eastern portion) of the body of the Great Sphinx were carved free from the rock, thus projecting from the rock outcropping, while what would later become the back or rump (western end) of the Sphinx originally merged with the natural rock. To be more precise, the rump was probably initially carved down only to the level of the upper terrace (about 11.5 feet [3.5 meters] above the present floor of the Sphinx enclosure at the rump), which to this day remains immediately west of the Sphinx within the general Sphinx enclosure; below the level of the terrace the back of the Sphinx merged with the bedrock. Hassan (1949) suggests that the Sphinx was originally meant to be viewed from the front (rather than from the sides or rear), such that, with the
A reasonable hypothesis is that when Khafre (circa 2500 B.C.) repaired and refurbished the Great Sphinx, the Sphinx Temple, and the Valley Temple, he either had the back (western end) of the Great Sphinx carved out and freed from the cliff or widened an existing passage behind the western end. It is difficult to argue that the back (rump) of the Sphinx was carved out and freed any later than Khafre's time; the rump has, like the rest of the core body of the Sphinx, been weathered and repaired with limestone blocks of various ages, including blocks that date back to at least New Kingdom times (see various articles by Lehner and discussion above) so the rump must have been freed well before New Kingdom times in order to have required repairs during the New Kingdom. Furthermore, one must account for the non-trivial four feet (1.2 meters) of subsurface weathering detected behind the rump of the Sphinx. It seems unlikely that this amount of weathering could have occurred since
As an alternative to the scenario that Khafre had the back of the Sphinx carved free from the bedrock, one could suggest that if the back of the Sphinx was already freed from the bedrock prior to Khafre's time, but only separated from the cliff by a very narrow passage, Khafre may have widened this passage and uncovered the limestone floor that we sampled seismically. Our seismic line was positioned very close to the western wall of the Sphinx ditch. The
Once exposed, the limestone floor on the western end of the Sphinx began to weather. Assuming that the floor of the western end was first carved out around the time of Khafre, and given that there is 50% to 100% deeper weathering of the limestone floor on the sides and front of the Sphinx as compared to the floor in back of the Sphinx, we can estimate that the initial carving of the Great Sphinx (i.e., the carving of the main portion of the body and the front) may have been carried out circa 7,000 to 5,000 B.C. (that is the initial carving of the core body of the Sphinx is approximately 50% to 100% older than 2500 B.C.). It can be argued that this tentative estimate is a minimum date; given that weathering rates may proceed non-linearly (the deeper the weathering is, the slower it may progress due to the fact that it is "protected" by the overlying material), the possibility remains open that the initial carving of the Great Sphinx may be even earlier than 9,000 years ago (see further discussion below).
Admittedly, estimating the date of the initial carving of the Great Sphinx by discrepancies in the depth of subsurface weathering below the floor of the Sphinx enclosure is less accurate and precise than we might desire. However, in the absence of other data and tests (such as proposed measurements of cosmogenically-produced isotopes in the surface layer of the rock of the Sphinx), we must work with the evidence at hand. I have pondered long and hard the many complex factors that could enter into the rate of subsurface weathering around the base of the Sphinx. Weathering rates may vary over time. As the climate was generally moister at an earlier period (prior to the middle of the third millennium B.C.) this might suggest that weathering progressed faster and deeper at this earlier period around the north, east, and south sides of the Sphinx (before the western end was freed from the bedrock). However, the subsurface weathering seen around the base of the Sphinx would not necessarily be accelerated by a moister climate per se.
The subsurface weathering is probably primarily a function of alternating periods of moisture collecting on the surface of, and penetrating within, the rock followed by evaporation -- this cycle might take place on a daily, seasonal, or longer time-scale. The effects of a rainy versus more arid climate may be fairly minimal in terms of this particular weathering phenomenon if the alternating cycle of moisture penetration and evaporation occurred on a regular basis (as it seems to at the present time within the Sphinx enclosure) under various climatic regimes. If the limestone floor of the Sphinx enclosure were completely covered with standing water that did not evaporate off, the standing water might serve more to protect the limestone than weather it (after all, the limestone was originally precipitated in water). In other words, the absolute frequency of the number of rain/evaporation cycles may be more important relative to the subsurface weathering than the absolute volume of rainfall. The Giza Plateau has had a mean annual rainfall of about one inch (2.5 cm) per year since
Taking the various factors that could affect the rate of subsurface weathering around the base of the Sphinx into account, as a first approximation I have simply assumed that the factors that would tend to accelerate the rate and depth of weathering are canceled by the factors that would tend to slow the rate and depth of weathering. On this basis I have used a linear extrapolation to estimate that the initial carving of the core body of the Great Sphinx occurred during the period of approximately 7,000 to 5,000 B.C. I believe that the estimate of 7,000 to 5,000 B.C. for the initial carving of the Sphinx is crude, but consistent and compatible with all of the other evidence at hand.
It should also be noted that we ran a north-south seismic line [line S9] through the
In addition to the unanticipated differential weathering around the body of the Great Sphinx, our seismic work also revealed several other interesting subsurface features. For example, there is clear evidence of a possible void or chamber under the left paw of the Sphinx (Dobecki and Schoch, 1992). The seismic profiles indicate that the Great Sphinx and
ARGUMENTS AGAINST THE GEOLOGICAL DATA SUPPORTING AN OLDER SPHINX
Recently the authors
Lawton and Ogilvie-Herald (page 313) agree with me that the current arid climatic regime of the Giza Plateau began approximately in the middle of the third millennium B.C. (circa 2350 B.C. by one standard dating scheme) and there were various periods of relatively heavy rainfall from about 10,000 or 8,000 B.C. up until the onset of the predominant aridity that has existed in the area for the last 4500 years or so.
Sporadic heavy rains and the resulting flash floods (due to the inability of the rain to penetrate and soak into the land's surface and thus it runs off and collects in valleys, wadis, and other depressions) commonly found in arid regions do have tremendous potential to move loose debris and even cause serious erosion. However, in my opinion as a geologist, the nature and especially degree of weathering seen in the Sphinx enclosure and on the body of the Sphinx itself, is incompatible with sporadic flash floods since dynastic times. Even if occasional heavy rains occur on the Giza Plateau, the fact remains that currently on average only about an inch of rain each year occurs in the region (25 to 29 mm annually).
I do not believe that there has been enough rainfall in the area over the last 5000 years to account for the tremendous degradation of the actual limestone bedrock as seen on the western end of the Sphinx enclosure, much less to account for the extreme weathering and erosion seen on the core body of the Sphinx itself. The latter is an important point, because in the case of the body of the Sphinx only the back (top) of the Sphinx serves as a catchment area for any subsequent runoff. From what we understand of the climate of the area, it strains credulity to suggest that this weathering and erosion is the result of rainfall during the last 4,500 years. This is even more so the case when we take into account the calculations of
Furthermore, based on the perceptive analysis of the geologist Colin Reader (1998; discussed below), since at least the time of Khufu (circa 2550 B.C. according to one standard chronology), the Sphinx has not even been situated in a position where it could receive the brunt of such flash floods. Among ancient Egyptian structures, those that show clear signs of having been damaged or otherwise significantly affected by the occasional heavy rains and resulting flash floods are those situated in valleys, wadis, and other low areas that serve as channels for the collected water.
Rather than addressing Gauri and Harrell indirectly via a discussion of
K. Lal Gauri has maintained that the weathering and erosion of the Sphinx and walls of the Sphinx enclosure are the result of the various effects of chemical weathering, particularly something known as "exfoliation" or the flaking away of the surface of the limestone. According to Gauri, dew that forms at night on the surface of the rock dissolves soluble salts found on the surface and then the liquid solution is drawn into tiny pores in the rock by capillary action. During the daytime the solution evaporates and salt crystals precipitate in the pores. As the crystals form they exert pressure which causes the surface of the limestone to flake away. This, in fact, is an important weathering factor that is currently taking place on the Giza Plateau. However, it alone cannot account for all of the weathering features seen in the Sphinx enclosure, and more importantly it alone cannot account for the specific distribution of weathering features actually found in the Sphinx enclosure (such as the more intense weathering, erosion, and degradation seen in the western end of the Sphinx enclosure, as discussed further below).
The weathering processes proposed by Gauri will also have their maximum effect under extreme arid conditions with the Sphinx exposed to the elements. When buried under a layer of sand, the Sphinx and Sphinx enclosure are on the whole protected from these effects. Also, interestingly, the flaking away of the rock as proposed by Gauri is (or at least should be) operating on all of the limestone surfaces of the Giza Plateau, yet somehow virtually no other surfaces show the same type of weathering and erosional profile as seen in the Sphinx enclosure. While I do not deny that salt crystal growth is indeed damaging the Sphinx and other structures during the present day, this mechanism does not explain the ancient degradation patterns observed on the Sphinx's body and in the Sphinx enclosure area but virtually nowhere else on the Giza Plateau.
Gauri has also suggested that the Sphinx and Sphinx enclosure have been, and are, subject to extremely rapid weathering, and he has pointed out that there has been significant deterioration of the Sphinx since the beginning of the twentieth century. As I have pointed out previously, however, and in all fairness
As I have discussed previously in a letter to the magazine "Archaeology" (Schoch,1995a), much of the Hawass-Lehner argument (Hawass and Lehner, 1994; see also Hawass, 1998, and Lehner, 1980, 1985a, 1985b, 1991, 1992a, 1992b, 1997), which is in large part based on the work of Gauri, for a younger Sphinx hinges on the assertion that its present style and rate of weathering and erosion is representative of its past weathering. Hawass and Lehner (1994) have stated that "ancient and modern weathering on the Sphinx are, for the most part, the same ball game." They discuss how soft the limestone is in some places ("you can crumble the stone with your fingertips") and the flaking of the stone to produce "giant potato chips" without realizing that these surficial weathering features are primarily due to modern assaults (pollution, acid deposition, salt deposited by rising water tables from the adjacent village and the damming of the Nile, and so forth) that have not been operating over the last five millennia. The work of K. Lal Gauri has documented the modern deterioration, as opposed to ancient weathering, of the Sphinx. In one publication Gauri illustrates, using comparative photographs from ca. 1925-26 and ca. 1980-81, how amazingly rapid this deterioration has been over the span of just a few decades (Gauri and Holdren, 1981). This contradicts the Hawass-Lehner assertion that the ancient and modern weathering are the same. Arguably the Sphinx has suffered more during the last century than it did during the previous 5,000 years.
It has also been suggested that the Sphinx has been heavily weathered by the action of subsurface ground water being sucked up into the pores of the rock by capillary action (
James Harrell is the major proponent of the " wet-sand" theory to explain the weathering and erosion of the Sphinx and Sphinx enclosure (Harrell, 1994). He has suggested that sand piled up for centuries in the Sphinx enclosure has been wetted by rainfall, Nile floods, and capillary action sucking water up into the overlying sand. Persistent flooding, however, would be expected to cut a wave bench into the Sphinx and the enclosure, and there is no such feature. Also, wet sand around the bottom of the Sphinx enclosure does not explain the obvious and pronounced weathering on the upper portions of the walls of the enclosure. Indeed, the major problem with the wet-sand hypothesis is that there is no documented mechanism known by which wet sand piled against a limestone surface will produce the weathering and erosional profile seen on the body of the Sphinx and on the walls of the Sphinx enclosure. Sand, even wet sand (if it ever occurred in the Sphinx enclosure - - there is no evidence that it did to any significant degree), may actually have served more to promote the preservation of the Sphinx. Furthermore, capillary action, far from being a mechanism cable of keeping numerous feet of piled sand wet over many centuries, is negligible in loose sands in arid areas. Harrell's "wet-sand" theory simply does not work as an explanation for the weathering and erosional features of the Sphinx and Sphinx enclosure.
On page 320 of their book, as if to put the final "nail" in the coffin of an older Sphinx, Lawton and Ogilvie-Herald write: "Finally, West and Schoch have increasingly fallen back on the evidence of the deep, rounded, vertical hollows in the west and south walls of the Sphinx enclosure, insisting that these are too ["too" is stressed by being placed in italics by L and O-H] obviously weathered by precipitation for the other arguments about weathering to matter. We have sympathy for this view, but again Gauri appears to have an answer. He suggests that they represent faults in the rock originating from the time when the structural deformation of the whole Plateau caused the rock strata to tilt, perhaps millions of years ago, and that they were widened into cavities or channels by the 'hydraulic circulation of the underground water'. They were then exposed when the bedrock was excavated from the Sphinx enclosure." Again, as I pointed out in the 1995 letter to "Archaeology," the limestones of the Giza Plateau are criss-crossed with fractures or joints, and these joints date back millions of years, and possibly some of them may be due to geologic faulting (but see comments by Coxill, 1998, quoted below). However, the joints are not opened up as fissures everywhere on the Giza Plateau. Vertical fissures such as those on the Sphinx enclosure wall can only be produced by water, primarily precipitation, and do bear on the age of the Sphinx. Basically the precipitation runoff follows paths of least resistance and thus works its way into weak joints and fractures. This is dramatically illustrated on the western wall of the Sphinx enclosure and the western portion of the southern wall (which have been subjected to substantial runoff) versus the eastern portion of the southern wall of the enclosure where the fissures are much less extreme; the eastern portion of the enclosure has not taken the brunt of the runoff. My critics, including Gauri, Lehner, Hawass,
Regarding these so-called "faults," the geologist David Coxill (1998, p. 14) notes: "The sub-vertical joints . . . are a distinctive characteristic of the surrounding pit [that is, the Sphinx enclosure], and to a somewhat lesser extent, of the Sphinx itself. They are natural fissures in the rock, that were formed by contraction of the carbonate rich sediments, when they were undergoing rockification. These are sedimentologically related fissures and not tectonic faults related to earthquakes, since they do not displace the strata. On the . . . Causeway edge, they are sometimes closed and grouted by fine grained carbonate sediments [a natural process], while others, are open at the top, narrowing, and eventually closing - - further down the vertical profile of the excavated pit face, and the sphinx's body . . . They represent lines of weakness that have selectively and progressively been exploited by the forces of weathering."
It is worth quoting Coxill (pages 16-17), an independent geologist who has taken the time to study the Sphinx first-hand, further on these issues: "[Robert Schoch] presented his findings . . . that the weathering features present [on the body of the Sphinx and in the Sphinx enclosure] are caused by rainfall that has cascaded over the sides of the monument and the surrounding pit . . .
Other theories have been put forward to try to counter the claim. Lal Gauri et al. (1995) consider that being porous, Member 2 limestone [of which the body of the Sphinx is carved], will suffer from morning dew condensation that dissolves salts within the limestone. When the heat of the day evaporates the water, the salts crystallise out and progressively exert minute pressure weakening the rock and opening up fissures already present. Both they, Hawass, and Lehner (1994), suggest that sub-surface water movements, during Eocene times, caused the fissures to open as the water table dropped. This is intriguing, but unlikely to be the case.
Firstly, condensation affects all monuments in the
Secondly, these weathering features require intense weathering to form their present profile, and, condensation/evaporation is a relatively mild and insignificant form of mechanical weathering in this arid climate.
Thirdly, fluctuations in the water table do not lead to fissures being produced wider at the top.
Lal Gauri [et al.] (1995) also suggest that the roundness of the laminars is due to gradational differences in the hardness of the strata. This does not account for variations in the weathering profile, within Member 2 beds, as previously discussed on the Sphinx's body or the presence of open fissures.
Harrell (1994) suggests that wet sands from
in the Sphinx enclosure and on the body of the Sphinx.
Ian Lawton and Chris Ogilvie-Herald (pp. 324-327), have also criticized my analysis of the seismic data. Unfortunately, they make a number of incorrect assumptions and perpetuate misunderstandings. For instance,
To further dismiss the seismic data,
Concerning the use of the seismic data to date the initial excavation of the Sphinx: It has taken about 4,500 years for the subsurface weathering at the younger, western-most floor of the Sphinx enclosure to reach a depth of about four feet (assuming that the western end was fully excavated to approximately its present state during Old Kingdom activity at the site). Since the weathering on the other three sides is between 50 and 100 percent deeper, it is reasonable to assume that this excavation is 50 to 100 percent older than the western end. If we accept Khafre's reign as the date for the western enclosure, then this calculation pushes the date for the Great Sphinx's original construction back to approximately the 5000 to 7000 B.C. range.
I believe this estimate nicely ties in with the climatic history of the Giza Plateau and correlates with the nature and degree of the surface weathering and erosion features. This estimate can be considered a minimum if we assume that weathering rates proceed non-linearly (the deeper the weathering is, the slower it may progress due to the fact that it is "protected" by the overlying material), and there is the possibility that the very earliest portion of the Sphinx dates back to before 7000 B.C. However, given the known moister conditions on the Giza Plateau prior to the middle third millennium B.C. versus the prevailing aridity since then, some might argue that initial subsurface weathering may possibly (but not necessarily) have been faster than later weathering, and this could counter balance the potential "non-linear" effect mentioned in the last sentence. In other words, the early moist conditions might, crudely, give deeper weathering which could appear to give it an "older" date but this is countered by the non-linear nature of the weathering which could appear to give it a "younger" date. In the end, based on many hours of analysis and rumination, I am satisfied that the two opposing factors roughly cancel each other out and a crude linear interpretation of the data is justifiable. In this manner, I return to my estimate of circa 5000 to 7000 B.C. for the oldest portion of the Sphinx, a date that is corroborated by the correlation between the nature of the weathering in the Sphinx enclosure and the paleoclimatic history of the region.
These same authors argue against the two-stage construction of the so-called Valley and Sphinx temples, pointing out that some granite blocks have actually been worked into the
Harrell has published various comments on the Internet concerning the geological evidence for the age of the Sphinx (Harrell, 2000). When I first read the latest comments by James Harrell, I immediately said to myself “here we go again.” Essentially, he is recycling some of the same tired arguments and misunderstandings, which have already been discussed and falsified in the literature, while adding further to the misconceptions.
In his opening paragraph Harrell claims that geologist Colin Reader “with slight modification” supports the dating of the Great Sphinx to the Fourth Dynasty, when in fact according to Reader the “excavation of the Sphinx” should be “tentatively placed sometime in the latter half of the Early Dynastic Period” or, in other words, in the Second or Third Dynasty (Reader, 1998; see further discussion of Reader’s paper below). Yes, Harrell later clarifies that Reader does not exactly agree with Harrell's date, but the way he first presents Reader as agreeing with a Khafre and Fourth Dynasty date is inherently deceptive. That “slight modification” of Reader's dating makes all the difference in the world. I may not fully agree with Reader's conclusions as to the absolute dating of the earliest portions of the Sphinx, but I do believe that Reader's meticulous study (Harrell's off-hand and anecdotal comments should not be allowed to detract from the importance of Reader's careful study) clearly establishes that the origins of the Great Sphinx are pre-Khufu. In fact, that is the crux of the debate over the age of the Great Sphinx as far as I am concerned. Is it
Harrell asserts that I have dated the Great Sphinx to 7,000+ B.C., when in fact, even though I do not absolutely rule out such an early date, I have stated on numerous occasions that I believe the geological evidence is quite compatible with a date of 5,000 to 7,000 B.C. However, I am not adamant about these dates whatsoever. For me, the important issue is whether or not the Sphinx is pre-Old Kingdom. I would note here, though, that my dating of 5,000 to 7,000 B.C. is partially based on an analysis of the seismic work that was carried out on the Giza Plateau with Thomas Dobecki (see comments above).
Contra Harrell, the low-velocity layer found under the floor of the Sphinx enclosure does not follow the bedding of the strata. The strike and dip of the limestone layers, as well as their composition, are clearly visible by observing the sides of the Sphinx enclosure. The differential weathering pattern that we recorded in the subsurface cuts across the dip of the strata and parallels the floor of the enclosure (as is to be expected of weathering). Furthermore, the dramatically shallower depth of the low-velocity layer immediately behind the rump of the Sphinx is totally incompatible with the notion that the seismic data simply records original bedding in the limestone. It is consistent, however, with the reconstructed scenario of the excavation of the Sphinx in stages that I have proposed. I am not simply mistaking a “shoal-reef facies” for a subsurface weathered zone and a “nummulite bank” limestone facies for unweathered subsurface limestone, as Harrell suggests.
Harrell asks how I know that the low-velocity layer seen under the floor of the Sphinx enclosure represents weathered limestone. He then goes on to state that “Nowhere has he [Schoch] ever given any evidence to support this claim. He has not dug or drilled into this layer and so has no idea of what is really down there.” Actually, this is not quite true (although I would add that, by the same token, Harrell “has no idea of what is really down there”). First, one can obviously observe the rock currently exposed on the surface of the floor of the Sphinx enclosure, and it is weathered limestone (and it should be, even according to Harrell's bogus “wet sand” hypothesis discussed further below). It is very strange to argue that the observed surface is weathered, yet the subsurface is unweathered, despite no differences in seismic velocities; this just does not make sense. I fail to understand Harrell's convoluted reasoning. Second, if Harrell had ever read the Geoarchaeology paper that Dobecki and I published (cited above), he would have noticed that several short seismic lines (lines S5, S6, S7, and S8) were run just north of the Great Sphinx on the terrace area in order to acquire velocities on undoubted disintegrated remains of the Setepet Member (the limestones of which much of the body of the Sphinx is composed) and the weathered Rosetau Member (which forms the lowest-most portions of the Sphinx and the floor of the Sphinx enclosure). In this area one can acquire both seismic data and look at the layers in cross-section (since the rock has been exposed as a nice vertical profile along the northern wall of the Sphinx enclosure). The Rosetau Member is weathered and we recorded velocities compatible with a weathered layer on the terrace. Similar velocities were recorded in the Rosetau Member under the floor of the Sphinx enclosure. The most parsimonious explanation is that the low-velocity layer represents a weathered zone, rather that hypothesize that it is following “original bedding” when the evidence is actually counter to such an interpretation. I stand by our analysis of the seismic data.
Concerning the surficial weathering and erosion observed on the body of the Sphinx and on the walls of the Sphinx enclosure, this has been discussed at length in many other places (see especially Reader, 1998). Harrell's “wet sand” hypothesis has no basis in reality, and in my opinion does not merit further discussion at the moment (see comments above). As far as I can determine, the “wet sand” hypothesis was invented simply to explain away the degradation features seen in the Sphinx enclosure. There is no evidence that either there was wet sand in the Sphinx enclosure for long periods of time or that such wet sand would cause the degradation patterns actually observed. Let it be said here that if there was any truth to Harrell's “wet sand” hypothesis or similar ad hoc hypotheses formulated to simply explain-away the surface weathering and erosional features observed on the Sphinx and in the Sphinx enclosure, then similar weathering and erosional features (similar in both nature and degree) should be observed on and in numerous Old Kingdom shaft tombs and other structures found on the Giza Plateau, but they are absent.
Harrell invokes climatic records from the past century to demonstrate that the Giza Plateau is rained upon periodically. Of course it is; that is hardly the issue. He also, less convincingly, argues that a sand-filled enclosure that is rained upon will remain wet for “many weeks or months due to capillary retention.” Actually, this is quite questionable (I don't believe there is any evidence to support Harrell's scenario along these lines), but in many ways it is beside the point. The real issue is whether wet sand piled against the limestone face will result in the degradation features and their distribution as actually observed in the Sphinx enclosure. I contend that the answer is no. Possibly wet sand against the limestone surface might result in some weathering of the rock, but it is uncertain to what degree. More importantly, wet sand piled against the limestone surface would probably protect the surface and impede the erosion of the rock (the actual carrying away of material), yet it is this pronounced erosion that is so prominent and important in the analysis of the degradation features seen in the Sphinx enclosure. Harrell's “wet sand” hypothesis cannot account for these features.
What can account for these features is surface rainfall runoff in pre-Khufu times, as so well elucidated by Reader's analysis (1998; see below). Harrell attempts to counter Reader's analysis by claiming, based on admittedly anecdotal evidence, that rainfall runoff still reaches the Sphinx enclosure and thus the degradation features observed today could have formed, according to Harrell, over the last 4,500 years. This, however, is despite the fact that Harrell states that he thinks “it is now universally agreed that the Sphinx spent most of its 4,500 year history buried in sand... ” and, as discussed above, it is not at all evident that the observed degradation features would even form when the Sphinx enclosure is filled with sand.
More importantly, however, is the fact that Harrell has no real handle on how much surface runoff there is now, or was in the past, or how it might actually degrade the limestones. His whole scenario is based on one anecdotal observation of a “torrent of water cascading into the enclosure during a rain storm” one night in 1990 or 1991. Exactly how much water (this might be difficult to observe at night during a sound-and-light show), why it was cascading (there has been much modern modification of the Giza Plateau),what effects it had on the stone, and so forth, are all open questions. Harrell's musings should not be considered to invalidate the serious geological investigations that have been undertaken on the Giza Plateau.
Harrell goes on to suggest that surface rainfall runoff is not really that important anyway, and states his belief that much of any rainfall will “sink into the limestone through its myriad fractures (joints) and then travel through these as well as along the bedding planes between the limestone layers.” This hypothesis, of course, counters his previous anecdotal evidence concerning a “torrent of water cascading into the enclosure during a rain storm.” To be blunt, I don't believe Harrell has any evidence that this is the case - - it is pure speculation on his part. It is important for Harrell to hypothesize this, however, if he wants to retain the traditional attribution of the Great Sphinx to Khafre of the Fourth Dynasty. Reader has made a strong case that surface runoff was responsible for the specific degradation features and their distribution seen in the Sphinx enclosure, and there was not sufficient runoff after the quarrying work done in conjunction with Khufu's pyramid (the Khufu quarry would have impeded surface runoff toward and into the Sphinx enclosure) to account for the pattern of degradation. Harrell argues (what he calls an “educated guess”): “The Khufu quarry would be no barrier to the subsurface flow of water and might even serve to collect the surface runoff and then channel it through the limestone on the west side of the Sphinx enclosure. I [i.e., Harrell] would expect it to emerge on the western walls as spring-like seepages along the bedding planes.” In fact, there is no evidence for such a process. I have studied the western wall of the Sphinx enclosure closely and I have observed no signs of such spring-like seepages, either in the recent or distant past. Indeed, this type of water flow through and over the limestones of the Giza Plateau would give a very different pattern of degradation than is actually observed. Simply put, the evidence does not support Harrell's “educated guess” whereas it does support Reader's analysis. Unfortunately for Harrell and traditional Egyptologists, the evidence is not compatible with the traditional attribution of the Great Sphinx to Khafre, circa 2500 B.C.
CORROBORATIVE GEOLOGICAL STUDIES CONCERNING
A GREATER ANTIQUITY FOR THE SPHINX
Two important geological studies have recently been carried out that go a long way toward supporting my basic analyses concerning the origins and history of the Great Sphinx. The first study, by the geologist David Coxill (1998), has already been mentioned and quoted above. After confirming my observations on the weathering and erosion of the Sphinx, and pointing out that other explanations (for instance, as proposed by Gauri and Harrell) do not work, Coxill clearly states (page 17): "This [the data and analysis he covers in the preceding portions of his paper] implies that the Sphinx is at least 5,000 years old and pre-dates dynastic times." Coxill then discusses very briefly the seismic work that Thomas Dobecki and I pursued and my estimate of an initial date of 5,000 to 7,000 B.C. for the earliest parts of the Sphinx based on the seismic data. He neither supports nor refutes this portion of my work, but simply writes (page 17): "Absolute dates for the sculpturing of the Sphinx should be taken with extreme caution and therefore dates should be as conservative as possible -- until more conclusive evidence comes to light." I can understand that he could take this stance, although perhaps I feel more comfortable with, and confident in, the seismic analysis we did. Coxill, in the next paragraph of his paper (page 17), continues: "Nevertheless, it [the Sphinx] is clearly older than the traditional date for the origins of the Sphinx -- in the reign of Khafre, 2520-2490 BC."
Another geologist, Colin Reader, has also pursued a meticulous study of weathering and erosion (degradation) features on the body of the Sphinx and in the Sphinx enclosure. This he has combined with a detailed analysis of the ancient hydrology of the Giza Plateau. Although as of this writing, his research has apparently not been formally published in journal or book form, Reader has been circulating his work as an illustrated paper entitled "Khufu Knew the Sphinx" (the copy I received from him is dated July 1998). Like Coxill, Reader points out the problems and weaknesses in the arguments of my opponents. Reader notes (quoted from the summary of his paper; no page number), that there is "a marked increase in the intensity of the degradation [that is, weathering and erosion] towards the west [western end] of the Sphinx enclosure." Reader continues, "In my opinion, the only mechanism that can fully explain this increase in intensity is the action of rainfall run-off discharging into the Sphinx enclosure from the higher plateau in the north and west . . . However, large quarries worked during the reign of Khufu [a predecessor of Khafre, the "traditional" builder of the Sphinx] and located immediately up-slope, will have prevented any significant run-off reaching the Sphinx." Thus Reader concludes (page 11 of his paper) that "When considered in terms of the hydrology of the site, the distribution of degradation within the Sphinx enclosure indicates that the excavation of the Sphinx pre-dates Khufu's early Fourth Dynasty development at
As I have discussed in my book, VOICES OF THE ROCKS (Schoch with McNally, 1999, 2000), I have come out strongly in favor of not only an older Sphinx, but also a contemporaneous (thus older)
One should note that Reader clearly accepts the Sphinx Temple as predating Khufu, and if it is correct that the Valley Temple was constructed from limestone blocks that came out of the Sphinx enclosure at a higher level than the blocks that were used to build the Sphinx Temple (as clearly stated by Lawton and Ogilvie-Herald in their book on page 329; I believe they may be correct here), then the Valley Temple must also be pre-Khufu (as West and I have hypothesized and advocated all along).
Reader tentatively dates the "excavation of the Sphinx" and the construction of the Sphinx Temple, Proto-Mortuary Temple, and "Khafre's" causeway to "sometime in the latter half of the Early Dynastic Period [page 11]" (that is, circa 2800 to 2600 B.C. or so) on the basis of "the known use of stone in ancient Egyptian architecture [page 8]." I believe that Reader's estimated date for the excavation of the earliest portions of the Sphinx is later than the evidence indicates. I would make three general points:
1) In my opinion, the nature and degree of weathering and erosion (degradation) on the Sphinx and in the Sphinx enclosure is much different than what would be expected if the Sphinx had not been carved until 2800 B.C., or even 3000 B.C. Also, mudbrick mastabas on the Saqqara Plateau, dated to circa 2800 B.C., show no evidence of significant rain weathering, indicating just how dry the climate has been for the last 5,000 years. I continue to believe that the erosional features on the Sphinx and in the Sphinx enclosure indicate a much earlier date than 3000 or 2800 B.C. It strains credulity to believe that the amount, type, and degree of precipitation-induced erosion seen in the Sphinx enclosure was produced in only a few centuries.
2) In his July 1998 paper Reader never addresses the seismic work that we pursued around the Sphinx, which is in part the basis I used to calibrate a crude estimate for the age of the earliest excavations in the Sphinx enclosure. In my opinion, the date estimate based on our seismic work is compatible with the type and amount of erosion and weathering seen in the Sphinx enclosure, and also nicely correlates with the known paleoclimatic history of the Giza Plateau.
3) I do not find dating the Sphinx on the basis of "the known use of stone in ancient Egyptian architecture" convincing. I would point out that massive stonework erections were being carried out millennia earlier than circa 2800 B.C. in other parts of the Mediterranean (for instance, at Jericho in Palestine). Even in Egypt, it is now acknowledged that megalithic structures were being erected at Nabta (west of Abu Simbel in Upper Egypt; discussed in the text of my book, VOICES) by the fifth millennium B.C. and the predynastic "Libyan palette" (circa 3100-3000 B.C.), now housed in the Cairo Museum, records fortified cities (which may well have included architectural stonework) along the western edge of the Nile delta at a very early date. I find it quite conceivable that architectural stonework was being pursued at
Reader sugg