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Rapakivi scarps at Morruuvuori

Morruuvuori is a rocky area consisting of coarse-grained porphyritic rapakivi granite which rises 40-47m above the surface of Lake Kuolimo. The bedrock in the area is intersected by vertical crevices running southwest-northeast and northwest-southeast, and also features horizontal cracking typical of rapakivi. The northwest-southeast cracking in particular is clearly visible as scarps and steppes in the northeast and southwest areas of the rock ridge. Typically of rapakivi, the rock has crumbled over time, and wedge-shaped piles of weathered gravel have tumbled down onto the hill slopes. The sand and gravel beaches are also washed with weathered gravel and they are a vibrant red due to the feldspar.

Rapakivi scarps at Morruuvuori

Experience the crumbled rock

The coarse-grained and porphyritic structure (meaning that rapakivi contains large feldspar granules) of the Morruuvuori rapakivi cause gradual separation of the bonding surfaces of minerals with different crystal structures during temperature fluctuations. As a result of this feature, which is typical of rapakivi granites, the structure of the rock is loosened and, over a long period of time, rapakivi crumbles into gravelly substance.

Morruuvuori is located on Kuolimo shore about 4 km southeast of Suomenkylä village. The Rapakivi scarps at Morruuvuori can be explored in summer by boat or along the ice during winter time.

Image: Tapani Tervo

Geological vocabulary

Coordinates

Geographic coordinates

61.279315612, 27.506396896

GPS-devices

x=527147,884 y=6794004,650