Karikkoselkä
Key facts
- Country
- Finland
- Diameter
- 1.4 km
- Age
- about 230 million years
- Location
- 62.22° N, 25.25° E
A small round bay of Lake Päijänne in central Finland, about 1.5 km across, surrounded by forest.
Karikkoselkä is a small impact crater about 1.4 km across, forming a round bay of Lake Päijänne in central Finland, near the town of Petäjävesi.
Discovery. The round shape of the bay drew attention, and in the 1990s geologists found boulders of breccia and shatter cones, cone-shaped fractures produced only by shock, in glacial deposits near the lake. Quartz grains with planar deformation features confirmed an impact.
What it hit. The impactor struck granite and other crystalline rocks of the Baltic Shield, about 1.9 billion years old.
Age. The age is poorly known. Estimates of around 230 million years, in the Triassic, are based on indirect evidence, and the true age may be quite different.
Why it matters. Karikkoselkä is one of a dozen known impact structures in Finland, a country of ancient rocks scoured by ice, where the hollows of craters often fill with water. The impactor is unknown.
Visiting. The bay can be seen from the shore and by boat. Finland's right of public access lets people walk in the forests, but do not collect from protected sites.
Did you know?
Karikkoselkä is a round bay of Lake Päijänne.
Shatter cones were found in boulders near the lake.
It is one of about a dozen known impact structures in Finland.