Kummakivi is an erratic boulder which was glacially transported to rest on top of a rôche moutonnée. The boulder is special since only around 0.5m2 of its surface area is in contact with the rock below it. The dimensions of the boulder itself are approx. 7m x 4m x 5m. There is a Saimaa Geopark sign at Kummakivenmäki parking area. Another sign is next to Kummakivi.
Kummakivi is protected as a natural monument outlined in the Nature Conservation Act.
Both the rôche moutonnée and the erratic boulder are mixed granite-cordierite-mica gneiss typical for the area, and the grooves and chatter marks tell of glacial erosion. The area emerged from underneath the continental ice sheet around 11,500 years ago, when the environment around Kummakivi differed drastically from that of today: instead of nestling in the shade of the forest, the boulder was perched on the shore of an ancient ice lake.
Near Kummakivi erratic there is a moss bridge or “sammalsilta” in Finnish, across Pitkäjärvi lake. The bridge was built by the Kaukas company in the 1930s and its original purpose was to shorten the distance of forest workers traveling from one side of Lake Pitkäjärvi to another. Today, the bridge serves Kummakivi erratic passers-by and other nature enthusiasts.
The path through the Kummakivi boulder and the moss bridge crosses varying terrain: Route description of the Kummakivi path and instructions for arrival
Videos made of Ruokolahti’s geosites can be watched on the Ruokolahti municipality’s YouTube channel.
Also read the story of Kummakivi (pdf) made in the Rural Explorer project (Story: Pekka Vartiainen, Translation: Annira Silver)
Coordinates: x=576136,600 y=6818572,600 (ETRS-TM35FIN)
The above coordinates are working in GPS-devices and for example in karttapaikka.fi service.
The below coordinates are working in Google maps service, which uses geographic coordinates:
Coordinates: 61.493320157, 28.430009592 (ETRS89 maantieteelliset(~WGS84))
Image: Arto Hämäläinen