THE SPHINX

Seismic Surveys of the Sphinx Area

Seismic geophysical surveys indicate that the subsurface weathering of 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 this area was excavated-and thus first exposed subaerially-one can tentatively estimate when initial excavation of the Sphinx enclosure may have begun. Dr. Thomas L. Dobecki, a seismologist with McBride-Ratcliff and Associates of Houston, Texas, assisted in carrying out some low-level seismic work in the vicinity of the Great Sphinx; this was done with the permission of the Egyptian Antiquities Organization.[17] We were able to gather a quantity of seismic data, and with this we have been able to establish subsurface geometries of the bedrock and have located several previously unknown sub-surface features. Seismic lines taken in front of and along the body of the sculpture on either side-east (seismic line S4), north (seismic line S1) and south (seismic line S2) of the monument-indicate that below the surface the limestone is weathered up to a depth of six to eight feet (1.8 to 2.5 meters). However, along the back-west side (seismic line S3) -of the Sphinx the identical limestone has been weathered only to a depth of approximately four feet (1.2 meters). These results were completely unexpected. The same limestone surrounds the great sculpture (the floor of the Sphinx enclosure where our seismic lines were taken consists of Gauri's [18] Rosetau Member, or Member 1), and if the entire body of the Sphinx was carved out of living rock at one time, it would be expected that the surrounding limestone would show the same depth of subsurface weathering.

One possible interpretation of this seismic data is that, initially, only the sides and front (eastern portion) of the Sphinx body were carved free of the surrounding rock, so that the Sculpture projected as an outcropping, with what would later become the figure's rump or rear (western portion) still merged with the natural rock. To be more precise, the leonine rump was probably initially carved down only to the level of the upper terrace, which to this day remains immediately west of the sculpture within the general Sphinx enclosure; below the level of the terrace, the backside of the figure merged with the bedrock. Egyptian Egyptologist Selim Hassan [19] suggested that the Sphinx was originally meant to be viewed only from the front (rather than from the sides or rear), so that, with the Sphinx Temple in front of it, it seemed to sit upon a pedestal.Alternately, the rump or western end of the sculpture may have been freed from the bedrock originally, but only by a very narrow passage not sampled by our April 1991 seismic line.