Deterioration of rock tombs saqqara area Egypt

Abstract

The present work focuses mainly on the deterioration of the mother rock (wall painting support) of rock -tombs at Saqqara area, e.g. Idut tomb; Old Kingdom, 6 th Dynasty, which have been hewn in the Upper Eocene (Maadi Formation) rocks.Petrographic characteristic and mineralogical composition of the mother rock and the plaster ground layer (preparatory layer) are carried out using polarizing microscope, X-ray diffraction (XRD) and differential thermal (DTA) analysis. Cross-Section of the mother rock, plaster layer and the painted layer are also investigated.The examined samples are mainly marlstones and argillaceous limestones. They are related into two main microfacies associations, fossilifferous micrite (mudston) and clayey biopelsparite (bioclastic pelloidal grainstone), respectively Rock texture, mineralogical composition and diagenetic process contribute, to great extent, the deterioration recognized by the mother rock and the plaster preparatory layer. The rocks of the mother rock are too weak to resist the interaction between exogenic (climate) and the endogenic (related to the nature of the rock types) conditions since their construction, thousands years ago.The durability of the mother rocks is mainly conditioned by their clay content and their porosity INTRODUCTION Saqqara area as known is a plateau formed mainly of well-stratified yellowish, argillaceous limestone, marl and calcareous claystones, with higher content of gypsum veinlets, and in part highly fractured with some cavities. They are related to lower part of the Maadi Formation, early Late Eocene (1) . The plateau shows a cover of Quaternary gravel, sand and conglomerate of varying thickness. In this vast Egyptologic area many rock -tombs, mostly related to the Old Kingdom, have been hewn within the Upper Eocene rocks. The walls of these tombs (mother rock) are cased by plaster ground layer (preparatory layer), on which the ancient paintings had been carried out. Most of those tombs show many signs of decaying.The most important stage of any stone conservation is the estimation of the nature of stones, their deterioration, and the causes of the decay. If the chemical, mineralogical and petrographical properties of the stones are neglected and not taken into consideration, the choice of the intervention technique may be