An Emerging Esker in Southern Finland

A partially submerged esker situated among a group of rocky islands on the northern coast of the Gulf of Finland is examined. As the esker emerged from the sea to form separate islands, the glaciofluvial material was deformed by current and wave action and redeposited. The contemporary rate of emergence is 1.8 mm per year. The structural differences in the primary esker have been emphasized by selective marine erosion. Differences in wave energy are reflected in the length of the fetch, which shortens towards the mainland and with land uplift. Shortening of the lateral fetch has prevented further marine erosion once the summit of the esker has been eroded to the level of the bedrock islands. Only in the direction of the open sea does the force of the waves continue unabated. This wave action has resulted in the formation of beach ridges on the southernmost tip of the esker. Elsewhere this same action causes longshore drifting, which has resulted in the development of spits and tombolos on the lee side of the esker islands.