The Absheron peninsula is located in eastern Azerbaijan, along the western coast of the Caspian Sea with layers of deposits from the Cretaceous, Palaeogene, Neogene, Pliocene and Quaternary periods. The lithological composition up to the Neogene layers is made up of clays, sandy clays, sands and limestones. Middle Pliocene sediments are sandy clays. These are thick in areas with highly mineralized groundwaters. Fresh groundwater is unable to permeate the thick clays to reach underlying sequences, by the overlying layers of sediment deposits have a lower salinity. In the western areas of the peninsula there are outcrops of low permeability clays from the Cretaceous, Palaogene, Neogene, and Lower Pilocene. These clays are deeper in the eastern areas and covered by Quaternary sediments. Although the peninsula is tectonically a southeast continuous of the Greater Caucasus, its Quaternary deposits are isolated.