When the inland ice sheet melted about 10,000 years ago, a large sea formed.
Distinct beach ridges took shape when the sea’s waves surged against the slope of Kilsbergen. As the land rose up from its covering of ice, new beach ridges were formed. The waves flushed away the finer particles such as sand and clay. Left behind were the larger stones, which were ground against one another and rounded, exactly the same as on today’s seashores.