Sea ice shaping the shores

The Baltic Sea region is characterized by very variable winter weather conditions. In severe winters, the Baltic Sea near the Estonian coast is totally covered by pack ice, whose thickness may achieve 20-30 cm. Some storms carry drifting ice far from its original location. A combination of high sea level and prolonged strong winds from a single direction forms preconditions for catastrophic ice movement to the coast. Large accumulations of erratic boulders characterize both ancient and contemporary shore formations in the northern Baltics. The genesis of such accumulations has been attributed mainly to drifting ice from near-shore water to the shore. Evidence of transported boulders are visible in spring at low sea-level conditions after the ice has melted. Large boulders sometimes accumulate on beach ridges at elevations of a couple of meters above the sea level and tens of meters inland from the shoreline. Our first studies on the structure and formation conditions of the hummocks of drifted ice on shore originate from February 1957, when 15 m-high blocks of ice were deposited on a sandy beach in Pärnu Bay. The latest studies on the impact of drifting ice on the structure and development of the Estonian seashores are from March to July 1997 on the northern coast of Saaremaa Island. The main goal of the current study is to identify the role of sea ice in shaping the accumulative shores of Estonia and its dependence on climatic conditions.