Flora and fauna
The outer and inner archipelago can show remarkable differences in fauna. Land-uplift has an impact on the development of plants in the shore zone, and shore plants are quickly replaced. On larger islands or in the inner archipelago, the shores are often covered by alder bushes that are replaced by birch or spruce higher up.
The same animal species are found in the archipelago as on the mainland, and for example elks are often found in the archipelago during the summer. The most common mammals found on small islands and skerries are field mice. The birdlife is rich in the archipelago; both nesting birds and birds passing through during migration are found here. For example, approximately 60 bird species are nesting regularly on the Valsörarna islands. Common fish species in the Kvarken region are, for example, perch, pike, whitefish and herring.
Both coastlines of the Bothnian Bay are characterised by the on-going land-uplift, which means that the land area is continuously growing. The land-uplift in the Korsholm archipelago is almost one metre in a hundred years, which means that places where it was possible to go by boat, fish or swim 50-60 years ago, are now dry land or shallow shore zones. Due to land-uplift, the archipelago is rather young, and at the start of the Common Era there was not very much of what is today’s archipelago above the water surface. In the 1000s, Replot, Björkö and Köklot were only small islands, and Vallgrund was a slightly larger island.
De-Geer moraines and devil's fields
De-Geer moraines are parallel ridges runing from north-east towards south-west, forming long peninsulas or long narrow islands. These moraines were formed during the Ice Age when the ice transported large amounts of stones and gravel. When the climate became milder and the ice melted faster than it moved forward in the summer, gravel and stones were left by the ice. During the winter, the ice was again gliding towards the south-east and the ice was then packing the gravel and stones on the ground. During this time the so called devil’s fields (stone fields) were also formed. One of the largest devil’s fields is found in Panike.