The carbonate rocks of the Sphinx were
structurally, chemically and mineralogically studied. The investigated rocks (Upper and
Middle Eocene age) suffer from both chemical and mechanical weathering. Human pollution in
addition to natural forces (wind, rain, dew, and temperature) have their environmental
impact on the rocks. Field observation revealed the presence of fractures in the form of
laminations and joints in addition to iron stained patches and thin sheets of salts in
some parts of the Sphinx, which can be related to the rock composition and to some
external factors. The upper layers
of the Sphinx are of marly and micritic limestones which suffer rapid alteration and
decomposition. The lower layers are dominated by dolomitic and sparry limestone which are
more compact and weather resistant. The chemical analysis of representative samples
reveals that some compounds such as SiO2, Fe2O3, MnO, P2O5,
Al2O3, MgO, CaO, Na2O, K2O, SO3, Cl,
L.O.I. and I.R. are variable in concentration depending on the composition of rock samples
and location of the sampled horizons. Therefore, the Sphinx rocks show complex problems
as: Contamination with halite, ground water percolation, jointing, cracks, and chemical
weathering in addition to the climatic factors which produce continuous fractured zones
and foliated layers on the surface of the statue.
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