It was initially believed that the Kura Depression (Basin) (megasynclinorium) (see Fig. 2.4) that separates the mega-anticlinoria of the Greater and the Lesser Caucasus was composed of thick sedimentary rocks deposited on the crystalline Pre-Alpine basement, and that these megastructures were separated by subvertical deep faults. In 1965, the Saatly superdeep borehole (SD-1) was drilled on the buried uplift of the basement of the Middle Kura Depression (predicted on the basis of high elastic wave velocities and rock densities; see Sect. 126.96.36.199). Analysis of magnetic properties of the rocks showed that the basement was not magnetized, and that a large portion of the geological section of the Middle Kura Depression consisted of Mesozoic magmatic associations of basic and intermediate composition with high magnetization (Khesin 1976). The mainly Jurassic associations are widely distributed in the north-eastern part of the Lesser Caucasus. The associations have a deep-seated underthrust of a gentle slope under thick sand-shale series of the Jurassic of the Greater Caucasus. These results were obtained by physical-geological modeling of the region (Khesin 1976; Khesin et al. 1983).