Even in the times of relatively stable sea level, coast lines kept shifting and settlements had to move along with the changing coast lines. The example shows the Danish coast around 900 and 2000. Large areas of the western part of what is today Denmark and Northern Germany has been inundated and partly eroded by the encroaching sea. Even today, coastal erosion is a serious problem in some of these (and other) coastal areas, threatening a lot of coastal high-value property.