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Mikkeli crater.

Mikkeli crater impact structure. Mikkeli crater an ancient impact crater remnant which was discovered in 2015 by amateur geologist.Shatter cones, horsetail-shaped formations in rocks specifically formed in meteor impacts, have been found in the area, but it is possible that the area containing shatter cones may be only the central uplift of the crater. Strong traces based on digital elevation data suggest possible ring structures from 100 km in diameter. This would make Mikkeli crater the largest impact structure in Finland surpassing the Lappajärvi crater. In addition to the shatter cones, microscopic studies of samples have revealed shock metamorphic features, in quartz grains, and formed carbon complex, which formed when the rock underwent extreme shock pressures of between 7–35 GPa (1,000,000–5,100,000 psi).

The age of the local granite bedrock of the Central Finland Granite Complex is 1.88 Ga (Paleoproterozoic). Since the impact, 7–8 km of rock has eroded away, according to several ice ages.

The edges form characteristic double wave symmetry comarable to Venus crater Cochran double-ring basin crater.

https://www.google.se/maps/@59.4084112,23.1548158,194740a,35y,42.75h,57.29t/data=!3m1!1e3