A stratigraphically recorded transgression deposit from a bog at 50 m above sea level near Lödöse, north of Gothenburg, has been analyzed with a view to determining its isolation course. Pollen and14C analyses were used for dating, and the interpretation of water‐level changes and isolation were based on diatom analysis. The transgression phase began at about 10,000 years B.P. and the basin was isolated before the time of the rational Corylus limit (C°), which in this area is at about 9,700 years