The Great Sphinx, located in Giza on the outskirts of Greater Cairo, is one of the world's most well known and important ancient monuments. To our knowledge, it was and is the largest sculpture ever made in the round from stone. It is also probably the oldest colossal sculpture, and is certainly the oldest existing colossal sculpture. Obviously, its preservation is not only important to Egyptians, but to the world as a whole. Likewise, were it to be lost, its absence would be a devastating blow, for it is certainly not only a colossal monument, but a symbol of mankind's earliest attempts at civilization. 

It is plain that extensive repairs have been made to the front paws of the Sphinx and in many other places over the body. Some of these repairs go back to the New Kingdom, probably dating to around 1400 BC (the time when King Tuthmosis IV set up his stela between the paws). At that time, Tuthmosis IV's craftsman may have even covered the body with large limestone casing slabs (known as Phase I restoration). Even then, the surface of the core body formed from Member II bedrock had probably eroded drastically into a profile of deep recesses and rounded protrusions, since Phase I work fills in these recesses. At the upper part of the rump and at the Sphinx's rear left haunch, huge boulders of bedrock had detached from the Sphinx body in ancient times, and were held in position by the Phase I restoration slabs. 

Ramesses II may have performed some restoration on the Sphinx, but there was also another major ancient restoration of the Sphinx, probably in the 26th Dynasty. This work involved filling in patches or covering the Phase I cladding with the same fine grained, homogeneous limestone employed in the first restoration. The Sphinx was once again repaired during the Roman era. This restoration, known as Phase III, patched and replaced parts of Phase I and II veneer using smaller blocks of white, relatively soft and friable limestone.  

There is also reason to believe that parts of the Sphinx must from the first have been added on to the carved body, out of necessity arising from the poor state of the rock. It is even possible that the body of the Sphinx was entirely plastered over at some stage. 

Attempts to restore it have often caused more harm than good. In the 1920s it was deemed necessary to support the head with cement approximations of the absent parts of the headdress, and it is these extensions that chiefly account for the altered appearance of the Sphinx's head in recent times, when compared with old photographs and drawings. It was Emile Baraize, who's team dug out the sand from around the Sphinx in modern times,  who effected these alterations, and it was he who also replaced many of the small blocks that had fallen from the Sphinx, and who added replacements of his own making from limestone. 

In 1979, the Sphinx project of the American Research Center in Egypt (ARCE), in collaboration with the German Archaeological Institute in Cairo, developed the first scale elevations and detailed plans of the Sphinx. The monuments phases of ancient and modern restoration were color coded on these drawings. At that time, masonry covered the body up to about one-third of its height on the north side and for about two-thirds on the south side. 

What became apparent from this work is that modern and Roman (termed, Phase III restorations) masonry began to flake and powder more quickly than the more ancient Pharaonic masonry (Phase I and Phase II), which developed a light brown patina that, in general, protected its surface for thousands of years. 

Scholars believe that the masonry repairs made between 1926 and 1973 probably flaked because of the properties of the stone, the higher salt content of the more recent stone and mortar and the way the blocks were laid. In the Roman and modern masonry, joints between small slabs are tight for only a fraction of an inch around their outer faces. The back of each slab is recessed, and the narrow space between adjacent slabs is filled with mortar. When the stones deteriorate, the contact between slabs is the first part to go, leaving the masonry adhering precariously to the backing mortar. 

In fact, during October of 1981, a patch of 1926 and Phase III masonry collapsed from the north hand paw, which called attention to the deteriorating condition of the Sphinx. Hence, between 1981 and 1982, a Sphinx Committee of the Egyptian Antiquities Organization (EAO, currently the SCA) made the decision to replace many of the Roman and Baraize restoration stones all around the body.  The team used some 2,000 new limestone blocks, which were larger than those of Phase III, as replacements, and simply discarded the old blocks.

During these restorations, apparently for the first time, systematic research on the water table, pollution and on the properties of the stone and mortar were undertaken. However, for some reason, none of these finding were applied during the 1980's to the restoration work which continued until 1987. 

During all of this, the exposed natural rock on the upper two-thirds of the north side was sealed by stone and mortar buttresses that filled in the weathered recesses and supported the overhanging layers of Member II type stone. The rump and the upper one-third of the lion body were also given the same treatment, and a new outer casing was begun over this buttressing, which changed considerably the appearance of the Sphinx. 

Unfortunately, the problems with the rock core body of the Sphinx were never addressed during this work, and while the buttressing and masonry cladding might stop large chunks of the Sphinx from falling, the effect of the new materials on the natural rock surface, which had been flaking and crumbling, remained unknown. 

In fact, by 1987, already the newly applied cladding had itself begun to flake because of efflorescing salts in the stone and mortar. Furthermore, the restoration slabs began to buckle outward and slip, particularly along the line of the Major Fissure on the Sphinx's north side, perhaps because of moisture emanating from the core body. It seemed as though the Great Sphinx was shedding an unwanted coat. This is why the work was suspended in 1987. In 1988, a large chunk of limestone fell from the south shoulder.

Afterwards, a new Sphinx Committee was formed in 1989, now consisting of scholars from the EAO, Egyptian universities and also foreign experts. They all agreed that the casing stones and the harmful cement and gypsum mortar of the previous restorations should be completely and immediately  removed. These stones, set in place between 1982 and 1987, were to be replaced using the plans and elevations of the ARCE Sphinx Project as a guide. Furthermore, special attention was to be given to maintaining the modeling of the paws and lion body seen in the ancient restorations. 

In the first phase of this new project, there was considerable analyses, and restorative work in selected areas, including the south forepaw, the south flank and the tail. During this work, the Egyptian National Research Institute of Astronomy and Geophysics studied the water table, which may have dropped due to a new sewage system installed in the nearby Cairo suburb of Nazlet el-Samman, one of several villages in the plain below the Giza Plateau. Also, a survey of quarry sites was made to find stone with consistent properties to those of the well preserved ancient repair stones. Such stone was found at Helwan. 

The new team of restorers is following the plan laid out in 1989. The stone repairs from the 1980s were apparently removed and the mortar packing cleaned out from this and previous modern restorations. 

Now, at a cost of about ten million Egyptian pounds, a team of sculptors (Adam Hunein and Mahmoud Mabrouk) and a restorer (Moustafa Abdel-Qader), replaced the cladding with new stones. Rather than using thin facing slabs that make contact with the core stone for only a fraction of an inch at the exterior face, the team laid blocks so that they are in contact for much of their thickness along the bedding plane and vertical joins.  They also employed a system of interlocking adjacent stones that permit easy replacement if any of the stones should deteriorate. 

They also used a mortar made of lime and sand, which was allowed to congeal for 10 to 15 days. This project was completed in 1998

Then, in May 1990, the Getty Conservation Institute installed a solar-powered monitoring station on the back of the Sphinx, in order to obtain additional information to analyze the Sphinx's deterioration. It was designed to measure such potentially destructive environmental factors as wind, particulates, rain, atmospheric humidity and condensation, vibrations and seismic shocks. The data so far has shown that a strong, sandy, north-west wind is the major source of wind erosion, while atmospheric moisture reacts with the salts in the limestone on a daily basis to produce the severe surface flaking of the rock core (Member II). Other studies have also shown problems related to structural instability. 

In order to address these issues, the Minister of Culture, which oversees the Supreme Council of Antiquities and thus the monuments of Egypt, convened the First International Symposium on the Great Sphinx in Cairo during February of 1992. It was attended by geologists, conservationists, art historians, chemists, archaeologists and Egyptologists. Unfortunately, the worst deterioration problems have not been resolved. 

The continuous deterioration of these layers is pronounced on the chest, which has not been covered in modern times by restoration masonry. However, a number of suggestions have been made.

Some scholars have recommended injecting the chest area with a chemical consolidant. However, there is insufficient data on the long-term effects of various possible consolidants. Others would like to encase it too with limestone to protect if from the wind, but this would drastically alter the appearance of the monument, and the authorities are not sure what would happen to the rock underneath. 

One specialist suggested returning the Sphinx to its state before the 1926 Baraize repairs, and then to "freeze" the statue in that condition.

All of the specialists have agreed that coordinated, systematic, apolitical research must be undertaken. For example, different treatments could be tried on temporary limestone walls, or on natural rock exposure in nearby Giza Quarries. These could be monitored over the course of two or three years to determine how the treatment performs.

In the final analysis, while the Great Sphinx of Giza is deteriorating rather quickly in terms of the vast period of time it has existed, it is not so rapid that we do not have time for more and better preliminary studies before restorations that may be more destructive than helpful. It appears that some of the additional research and analysis is indeed being done. Nevertheless, some of the deterioration is alarming, and much more analysis and work needs to be completed as soon as, but also as carefully as possible. 

See Also:

• An Introduction to the Great Sphinx
• The Great Sphinx Temples
• Conservation of the Great Sphinx
• The Meaning of the Great Sphinx
• Sphinx in Pictures
• Age of the Sphinx