ИСТИНА

The geological structure and evolution of large barrier-lagoon systems in the eastern and southeastern coasts of the Baltic Sea are considered. The data available on some coastal deltaic plains in the Leningrad Region, Latvia and Lithuania are discussed in some details. The considered materials lead the authors to the conclusion about a unified mechanism of the systems’ development. A considerable rise of the sea level at the Littorina Sea transgression fostered large transgressive bars developing at the margins of deltaic plains and lagoons formation on the surface of these plains.