Grawitacyjne ruchy masowe na obszarze Gdyni udokumentowane na dawnych mapach i w źródłach archiwalnych

The article deals with selected examples of old nautical maps (portolans), topographic maps, archival materials of the 19th century German language studies, which are valuable sources of information on the history of landslide processes. The city of Gdynia was founded in 1926, and its location despite very unfavourable formation of mass movements, was determined by economic and political reasons. As documented on nautical maps from 1596, landslides have been occurring in the coastal zone of today’s Gdynia since at least the 16th century. Within the limits of the zone, the oldest structural damage has been observed. The Urmesstischblätter map from 1837 documented damage to the redoubt in Cypel Oksywski. These fortifications, which were erected during Napoleonic Wars between 1810 and 1812, were completely rouined in the first half of the 19th century. It was the first time when mass movement resulted in financial losses in Poland’s coastal zones. Compared with the present, the 19th century saw an increase in mass movement activation in coastal zones. Between 1837 and 1909 the maximal changes in Cypel Oksywski were 2.2 m a year. The landslide in Cypel Oksywski is also the first stabilized landslide within the city limits of Gdynia. It also has the longest history of stabilizing efforts that go back to 1909. This article shows, based on the study of a landslide in Wielki Kackfrom 1930, that in the development of the city of Gdynia virtually from the beginning of its foundation in 1926, man-made dangerous gravitational processes have always been present.