Grain-size distribution of sea floor deposits of Nõva Bay and Keibu Bay, northwestern Estonia, is discussed.Based on grain-size statistics, the lateral and vertical distribution of different types of bottom sediments is shown and compared for the two bays.The bottom deposits consist mostly of sand (80-100%).The proportion of silt and gravel is considerably smaller: up to 3% in Nõva Bay and up to 7% in Keibu Bay.In Nõva Bay medium sand predominates.Grain-size distribution of deposits is rather uniform and an obvious correlation exists between the occurrence of different fractions and the water depth.In Keibu Bay sand of different grain size prevails.Along the boundary between the mouths of the bays and the open sea, a belt of coarse sand runs parallel with the shoreline.Beyond this belt silt and clay are predominant.
This study documents seafloor morphology and sediments based on multibeam, side-scan sonar and boomer surveys, as well as sediment samples taken on the inner to mid shelf of the Andaman Sea after the 2004 Indian Ocean tsunami. Preservation of submarine relief in former underwater mining areas points to limited impact of the tsunami, while channel structures parallel to the observed tsunami backwash indicate a possible higher impact. Therefore, the tsunami impact seems to be focused on some areas. The impact was probably most effective during the backwash, when stiff mud deposits containing grass, wood fragments and shells were transported by high density backwash flows. Moreover, several boulders, which might have been deposited during the tsunami backwash flow, were found in the channels in front of Pakarang Cape.
Submarine hard bottoms (e.g., boulders, outcropping strata) are of particular ecological importance. They were investigated in the Exclusive Economic Zones (EEZ) of the German North Sea and the Baltic Sea, using high-resolution seafloor imaging techniques (i.e.,...
Sedimentary processes and the evolution of the wave- and tide-dominated, asymmetric Parnaíba Delta during the late Holocene were investigated based on
The paper considers the distribution of bottom deposits in Tallinn Bay in connection with the general geological setting.The shores subject to intense ship wash (western coast of the Viimsi Peninsula, SW coast of Aegna Island, and eastern coast of Naissaar Island) are discussed in greater detail.Distribution of bottom deposits is determined by the location of erosion areas and seafloor topography.The shores of the bay are mostly covered with coarse material washed out from glacial deposits, which reduces the influence of the waves.During the periods with low water level the waves generated by fast ferries influence deeper parts of the nearshore.
