Browsing by Subject "muinaisranta"

Tilting, caused by glacioisostatic land uplift, and sea level have changed dramatically in regions near the Kattegat during Late Weichselian and Holocene. These changes have also had a profound impact on the Baltic Sea by affecting its connections to oceans. To estimate the relative sea level in the Kattegat and nearby regions on the coasts of Denmark, Sweden, Norway and Germany, dataset of 81 raised shorelines and lake isolation thresholds was collected from published peer-reviewed journals. Based on this dataset three spatial models of 11000, 7900 and 4900 year ago time windows were made with ArcMap program. In addition to the dataset, shore level displacement curves and tilting estimates were used in the models. Dummy-point curves of land uplift isobases were made as part of modeling and many methods were used to place these including following current land uplift isobases, shapes of ice sheets and glacial thickness and combinations of other methods. Triangulated Irregular Network (TIN) interpolation method was used to interpolate areas between these isobases and to create sea level layers representing sea levels in the models. Clear changes are visible in different time windows. 11000 years ago the Baltic Sea basin had a narrow connection to ocean trough the Lake Vänern, Southern-Sweden and Jylland were connected by land and continental ice sheet was still connected to ocean at the Oslofjord. 7900 years ago ocean connection of the Lake Vänern had terminated, Danish Straits had opened up and sea level was higher than today in north-eastern modeled areas and lower than today in south western areas. 4900 years ago relative sea levels at north-western and north-eastern coasts of Germany were lower than today, Kattegat and Skagerrak had higher sea levels than today and so did the Danish Straits, leading to higher salinity conditions at the Baltic Sea. In this study limited point data was used to obtain spatially extensive data of sea level changes in the Kattegat and the surrounding areas.