Sediment coring stations and archaeological sites in the Baltic Sea region. Location of the sediment study sites are indicated with red dots with the location of the key-site 303600 labeled. The inset shows the location of the Baltic Sea area in Europe. Radiocarbon dates for the population proxy were taken from archaeological sites within the brown polygon. The Baltic Sea´s modern bathymetry is shown along with the Baltic Sea basins: AB – Arkona Basin, BB – Bornholm Basin, GdB – Gdansk Basin, GB – Gotland Basin, FD – Fårö Deep, LD – Landsort Deep, NCB – Northern Central Basin. The maps were created using the software package GrADS 2.1.1.b0 (http://cola.gmu.edu/grads/), using published bathymetry data42,43.