The origin of soluble salts in rocks of the Thebes Mountains, Egypt:: The damage potential to ancient Egyptian wall art

Soluble salts are indigenous to the marine sediments of the Esna Formation and Thebes Formation in central Egypt. Natural weathering processes and human impact cause salt efflorescence in tombs and on walls of ancient Egyptian monuments in the Theban Necropolis, resulting in the disintegration of wall paintings and carved hieroglyphs. Determination and quantification of soluble salts and measurements of the porosity were done on tomb marls in order to understand the origin and damage potential of the salts in the royal tombs of the Valley of the Kings. The study shows that sodium chloride (NaCl) is the predominant salt species. Sulphates, anhydrite (CaSO4) and gypsum (CaSO4 . 2 H2O) also occur in the limestone deposits of the Thebes Formation and the underlying shale deposits of the Esna Formation. Member I of the Thebes Formation, into which most of the ancient tombs were hewn, shows the highest amount of soluble salts (up to 6,2wt-% dry). In addition, the porosity and permeability of the marls in Member I are high, enhancing water molecules and brine migration. Wetting and drying of the tomb surfaces in the past has affected solution, transportation and recrystallization of water soluble minerals, and has led to major destruction of wall paintings and ornamentations. This study shows that large amounts of salt minerals still remain in the wall rocks. Future humidity changes due to flash floods and tourists may favour salt crystallization in the ancient Egyptian monuments. The authors urge the authorities to undertake steps to prevent further destruction to save the magnificent cultural heritage found in the Thebes area. Copyright 2000 Academic Press