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Morpholithodynamical changes of the beach and the nearshore zone under the impact of submerged breakwaters – a case study (Orłowo Cliff, the Southern Baltic)

Kubowicz-Grajewska A.

Oceanologia

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2015

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No. 57 (2)

144--158

EN

Submerged breakwaters (SBWs) were used for the first time on the Polish coast in 2006, in the western coast of Gdańsk Bay, in the area of Orłowo Cliff. They were built to prevent the abrasion and inundation of areas situated in the hinterland, especially in the conditions of storm surges. The main objective of the study was to determine their effect on the morphology and grain size composition in the seashore and nearshore zone. Based on the conducted research and analysis, it has been found that the construction has a minor impact on the modification of the shore and nearshore zone morpholithodynamics, which is evidenced by a sinuate shape of the shoreline and a relatively stable cape in the central part of the area, present both before (1966–2005) and after SBWs were built. Furthermore, the progressive abrasion, the lack of significant changes in the morphology and particle size distribution of the beach and the nearshore zone, as well as the fact that those changes are limited only to the immediate surroundings of the submerged breakwaters prove their neutral impact.

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Cementacja węglanowa osadów piaszczystych klifu w Gdyni-Orłowie

Ciborowski T., Jankowski M.

Przegląd Geologiczny

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2007

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Vol. 55, nr 2

140-145

EN

Carbonate cementation of sandy sediments is most common in tropical and subtropical climate, and quite rare in temperate climate. About 20 sites where carbonate cemented sandstones occur are known throughout the Polish Lowlands. A new outcrop of carbonate cemented sandstone was found near Gdynia-Orłowo (coast of the Gulf of Gdańsk). Field studies and microscopic analyses [optical microscopy and SEM] let to recognise the pattern of cementation of sandy sediments. Origin of the sandstones is connected with infiltration of rain water into glacial till (partially cracked). This till is the source of calcium carbonate transported by water into underlying fluvioglacial sands. Because of different sediments porosity and resulting degassing of CO2, CaCO3 precipitated. Additionally, elevated temperature and evaporation of water may also create favorable condition for precipitation. The process of cementation is related to the exposition of fluvioglacial sands layer caused by cliff abrasion (about 1 m per year). The best geochemical conditions for precipitation of CaCO3 are in the zone of contact with atmosphere, so this cementation seems to be recent. Carbonate cemented sandstones formed below the glacial till fall down and may be found in the colluvium of the cliff slope.

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Budowa geologiczna i glacitektonika klifu orłowskiego w Gdyni

Kaulbarsz D.

Przegląd Geologiczny

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2005

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Vol. 53, nr 7

572--581

EN

The Orłowo Cliff is built of glacial and fluvioglacial deposits, Middle Polish Glaciations (possibly Odranian and Warthanian) and Vistulian Glaciation. Deposits are heavily deformed glaciotectonically. In the northern part of the cliff, Miocene sediments are exposed. It is possible, that the Miocene sediments were dislo-cated from their primary position. There were observed overthrusts and intermingling with Pleistocene material in the lower part of the exposure. The Orłowo Headland is built of glacial tills. It is probably a part of fold, similar in pattern to the structure of overthrust folds present in silty-sandy-grained deposits in the southern part of the cliff. Apart from folds and overthrusts there are many faults and the boudinage. Structural analysis of glaciotectonic deformations in conjunction with origin of deposits and statigraphic research enabled the recognition of several stages of development of deformations. Two local directions of glaciotectonic transport were marked clearly: from the north-east, which was connected with glacier invasion in the OEwiecie Stadial of the Vistulian Glaciation, and direction from north-west (north north-west), related to the Main Stadial of the Vistulian Glaciation.