Little Ice Age Flooding in the Ivalojoki and Oulankajoki Valleys, Finland?

ABSTRACT

Scroll topographic features, identical in the meander belts of both rivers, are indicators of ancient floods. The highest scrolls are dated dendrochronologically to around 1780 and the youngest to around 1840. A soil horizon buried beneath flood deposits gives radiocarbon dates consistent with the dendrochronological findings. Indirect indicators of floods include deflation surfaces and aeolian mounds.

The significance of the floods is assessed in terms of climatic ‘normality’, based on temperature and precipitation data for Leningrad, Kuusamo, Stockholm and Vardø. It is concluded that the considerably more positive water balance which prevailed during the Little Ice Age must have created conditions under which very much more extreme flooding could have taken place than has been normal during the present century. The timing of the peak floods to the 1780's appears to coincide with the exceptionally long and cold winters, which may have been the basic reason for the extremely high positive water balance at that time. The termination of the flooding by the middle of the 19th century proves to be highly compatible with general climatic trends.