The morphology of sand spits and the genesis of longshore sand waves on the coast of the eastern Gulf of Finland

A study of the southern coastal zone of the eastern Gulf of Finland found sand spits up to 1100 m long and up to 200 m wide, with sand cusps 15 to 100 m wide moving eastward along the shoreline. Similar morphological forms have been described as long–shore sand waves associated with high energy coasts. This article presents the results of field geological and geomorphological studies and retrospective analyses of remote sensing data (airand satellite photos of on–shore and near–shore parts of the coastal zone). The development of the long–shore sand waves in the study area is explained by the fact that prevailing waves induced by the westerly winds propagate almost parallel to the coast. It is shown that under these conditions the shoreline contours become unstable and any small perturbations to the shoreline extend these contours with time.