ABSTRACT
The Daquan River running in front of the Mogao Grottoes has been formed by a conjugate fault system and frequent floods since the beginning of the Quaternary period. The foundation rock of the Mogao area consists of two different strata, namely the Precambrian gneiss and the Pleistocene conglomerate. During the late Tertiary period when aggressive tectonic movements took
1 INTRODUCTION
Most people tend to think that there is no water in any arid areas that the earth is completely dry. This is not correct. Groundwater must exist even in an arid area such as a wide desert spreading Egypt. (Tanimoto et al. 1992; Tanimoto et al., 1993) Groundwater can incredibly move in far distance, sometimes over several thousand kilometers through faults and pores in solid rocks, fissures, and faults. When groundwater, even moisture, moves along the same path repeatedly over a long time, salt substance is transported one place to another, and evaporation accelerates the accumulation of salt(s). The Mogao Grottoes are not exceptional as well. It happens behind many wall paintings and generates the separation of paintings.
