Development of an ancient shoreline database to reconstruct the Litorina Sea maximum extension and the highest shoreline of the Baltic Sea basin in Finland

An ArcGIS geodatabase called the Ancient Shoreline Database (ASD) was developed for the study and interpretation of ancient shorelines and shoreline displacement information. It was further divided into the Isolation Database (ISD) and Shoreline Landform Database (SLD) based on the characteristics of the available information. In the current study, observations related to the maximum extension of the Litorina Sea and the highest shoreline in Finland were carefully recorded and classified in the ASD. A total of 1625 shoreline observations were stored in the ASD, of which 106 were stratigraphic data points from dated isolation horizons (ISD) and the remaining 1519 were data points representing morphological shoreline observations (SLD). This paper describes the content of the ASD in terms of the variability and reliability of collated data points, but also introduces how modern LiDAR-based digital elevation models were utilized in validating the published observations as well as in interpreting new data points related to ancient shorelines from areas lacking information. The compiled ASD was used to reconstruct the diachronous maximum extension of the Litorina Sea and the highest shoreline of the Baltic Sea basin in Finland.