In this paper systematics of the gastropods of the Quaternary deposits were studied in the Caspian Sea in an exploration well in the northern city of Aq Qala in Golestan province. In this subsurface studied, total thickness of Quaternary deposits is 2585m. A Total of 11 species, 8 genera of 5 families of gastropods are reported. The identified gastropods show that since the beginning of the Quaternary the contents of these gastropods in the Caspian Sea have been adapted to sea level fluctuations.