Utwory trzeciorzędowe w obszarze południowego Bałtyku obejmują wycinkowe fragmenty profilu stratygraficznego reprezentowane przez paleocen dolny, eocen górny, oligocen dolny oraz miocen dolny i środkowy. Młodsze ogniwa trzeciorzędu – oligocen dolny oraz miocen dolny i środkowy rozpoznane są dotychczas tylko w bliższym sąsiedztwie brzegu oraz w klifach. Plejstocen jest reprezentowany głównie przez osady zlodowacenia warty i wisły. Pełny profil holocenu występuje jedynie w głębokowodnych basenach sedymentacyjnych. W obszarze płytkowodnym osady młodszego holocenu występują tylko lokalnie. Osady środkowego i późnego holocenu, reprezentowane przez piaski i żwiry morskie, na dużych obszarach leżą bezpośrednio na glinach zwałowych. Długotrwałe okresy denudacji przypadające na koniec trzeciorzędu i początek czwartorzędu, na które nałożyły się procesy plejstoceńskiej egzaracji glacjalnej i erozji subglacjalnej są głównymi czynnikami odpowiedzialnymi za styl budowy geologicznej obszaru i rozwoju rzeźby. Główne elementy współczesnej rzeźby są wynikiem procesów erozyjnych zachodzących podczas holoceńskich transgresji południowego Bałtyku.
EN
Tertiary deposits in the area of the Southern Baltic represent only some parts of the stratigraphic column: Lower Palaeocene, Upper Eocene, Lower Oligocene, and Lower and Middle Miocene. Younger members of the Tertiary are known only from coastal zone area. Pleistocene is represented mainly by deposits of Wartanian and Vistulian glaciations. Full sequence of the Holocene occurs only in deep water basins. In the shallow water area the Early Holocene deposits occur only locally. On large areas Middle and Late Holocene marine deposits are laying directly on top of till. Long-lasting denudation processes at the end of Tertiary and beginning of Pleistocene as well as glacial erosion during the Pleistocene are responsible for the origin of Baltic depression. The main features of present day morphology of the sea floor is a result of marine erosion during the Holocene transgressions.
2
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Selected results of the joint geological investigations of the Southern Baltic are presented, mainly related to geological cartography and environmental geology (e.g., sea bottom contamination). The results of international projects expand the knowledge of bathymetry, seabed sediments in the Polish Exlusive Economic Zone and other data obtained by the Marine Geology Branch of the Polish Geological Institute during its 35 year research activity on the Baltic Sea. The PGI participates in research co-operation with neighbouring Baltic countries (especially Germany, Lithuania, Russia, Sweden, and Finland), but also with geological surveys of Great Britain and the Netherlands conducting joint research in the Polish part of the Baltic Sea.
The coastline in the Jastrzębia Góra area can be divided into three major zones of general importance: a beach and barrier section, a cliff section, and a section protected by a heavy hydrotechnical construction. These areas are characterised by a diverse geology and origin, and hence different vulnerability to erosion. In addition, observations have demonstrated a different pace of erosion within each zone. Based on the results obtained by remote sensing methods (analysis of aerial photographs and maps), it has been determined that the coastline in the barrier area, i.e., to the west of Jastrzębia Góra, moved landwards by about 130 m, in a period of 100 years, and 80 m over about 50 years. A smaller displacement of the shoreline could be observed within the cliff. Between the middle of the twentieth and the start of the twenty-first centuries the shore retreated by about 25 m. However, in recent years, an active landslide has led to the displacement of the uppermost part of the cliff locally up to 25 m. Another issue is, functioning since 2000, a heavy hydrotechnical construction which has been built in order to protect the most active part of the cliff. The construction is not stable and its western part, over a distance of 50 m, has moved almost 2 m vertically downwards and c. 2.5 m horizontally towards the sea in the past two years. This illustrates that the erosional factor does not comprise only marine abrasion, but also involves land-based processes determined by geology and hydrogeology. Changes in the shoreline at the beach and barrier part are constantly conditioned by rising sea levels, the slightly sloping profile of the sea floor and low elevation values of the backshore and dune areas. Cliffs are destroyed by mass wasting and repetitive storm surges that are responsible for the removal of the colluvium which protects the coast from adverse wave effects. Presumably, mass movements combined with groundwater outflow from the cliff, plus sea abrasion cause destabilisation of the cliff protection construction.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.