Karikkoselkä

Karikkoselkä Impact Crater

Karikkoselkä is an impact crater located in Petäjävesi, in the Central Finland region. It is distinguished by its remarkably round shape, a feature that sets it apart from the typically elongated lakes formed by glaciation in the surrounding area. The crater is the smallest identified impact structure in Finland, with a diameter of 1.4 kilometers and an original depth of 150 meters. The lake that now occupies the crater has a maximum depth of 26 meters due to sedimentation.

Geological Significance and Confirmation

The impact origin of Karikkoselkä is well-established through multiple lines of geological evidence. Numerous shatter cones, rock formations indicative of extreme impact pressures, have been discovered in the vicinity of the lake. Aeromagnetic maps reveal a distinct magnetic anomaly within the crater area, further supporting an impact event. Scientific confirmation has also been obtained from samples collected during deep drilling operations into the lake bed.

Age and Geological Context

Karikkoselkä is estimated to be between 230 and 450 million years old, with the most probable age being around 240 million years. This places the impact event during the Triassic period, or potentially earlier. The bedrock in the region, part of the Central Finland Granite Complex, formed much earlier, in the late Paleoproterozoic era, approximately 1.88 billion years ago. Some sources have mistakenly attributed a much younger, geologically improbable age of 1.88 million years, likely a misinterpretation of the bedrock formation age.

Archaeological Interest

Evidence of a Neolithic settlement has been found on the southern shore of Karikkoselkä. While a commemorative plate marks the site, no excavations have yet been conducted, and the precise age and nature of this ancient settlement remain undetermined.