Romsskåla and Sønndalslia

To the east of Leka municipality - on the island Austra – the bedrock is completely different from the Leka ophiolite complex. Austra forms the northernmost part of the Western Gneiss Region and consists mainly of Paleo-proterozoic orthogneiss es (1800-1850 million years old) with in-folded thrust sheets of mica schist, calc-silicate schist, marble and amphibolite. The orthogneisses are correlated with the Svecofennian province in Sweden, weheras the metamorphic rocks in the thrust sheets have been assigned to the Skjøtingen Nappe (a local equivalent of the Seve Nappe). The metamorphic rocks in the thrust sheets probably formed along the outer margin of Baltica. Thus, in contrast to the situation in Helgeland and Leka, where the rocks formed along the Laurentian margin, the rocks on Austra have their origin in Baltica. These contrasting rocks units were juxtaposed as a result of the Laurentia-Baltica collision during the final phase of the Caledonian orogeny around 400 million years ago. Local, early Silurian migmatitization of the orthogneisses was a response to the stacking of rock units during the collision.

A marked hiking trail leads to the top of Romsskåla, which is the highest peak in the municipality, 588 m.a.s.l. The hiking trail passes close to Sønndalslia, an area underlain by the Baltican metamorphic rocks; i.e. lime-rich meta-sedimentary bedrock such as calc-silicate schist and gneiss, marble and calcareous schist as well as biotite-rich sandstone and micaceous schist. This area has a high biodiversity with a boreal rainforest, and is protected as a natural reserve (Sønndalslia is listed as a non-geological site in the geopark).

Tourists use this site as a hiking destination. The difference between the different bedrock and vegetation make this site suitable for education purposes.