THE SPHINX

This phase of conservation has secured an improvement in the Sphinx's environment as a result of another study by the National Research Institute of Astronomy and Geophysics, this one of the seismic waves emanating from blasting activities at quarries in the vicinity. These waves were determined to be of potential hazard to the Sphinx. Therefore, based on recommendations from this study, limits were placed on the size of the blasts, and schedules were established to space out the detonations so as to prevent overlapping. Recording stations were set up in the Sphinx complex to monitor compliance with these restrictions.

In May 1990 the Getty Conservation Institute of the United States installed a solar- powered monitoring station on the back of the Great Sphinx designed to measure such potentially destructive environmental factors as wind, precipitation, relative humidity, and condensation. Data collected thus far indicate the strong, sand-bearing northwest wind as the principle source of wind erosion. They also indicate that moisture in the atmosphere, reacting on a daily basis with salts contained in the limestone, contributes at least in part to the surface flaking of the Sphinx.

Samples of rock taken from the Sphinx and surrounding outcrops were analyzed by the Petroleum Research Institute in Cairo, permitting composition analyses