Saarijärvi
Key facts
- Country
- Finland
- Diameter
- 1.5 km
- Age
- more than about 600 million years
- Location
- 65.28° N, 28.38° E
A small lake about 1.5 km across in the forests of north-eastern Finland, near Taivalkoski. The crater lies beneath it.
Saarijärvi is a small impact crater about 1.5 km across beneath a lake of the same name near Taivalkoski in north-eastern Finland.
Discovery. The structure was found through geophysical surveys, which showed a round pattern beneath the lake. Drilling in the 1990s found a bowl filled with sediment and broken rock. Quartz grains in the breccia contain planar deformation features, produced only by shock, confirming an impact.
What it hit. The impactor struck granite and gneiss of the Baltic Shield, more than 2.5 billion years old. The crater was then filled with sediment, which protected it from erosion.
Age. The sediments filling the crater contain microfossils of late Precambrian age, showing that the impact happened more than about 600 million years ago.
Why it matters. Saarijärvi is one of several small, ancient craters in Finland preserved because they were quickly filled with sediment. The impactor is unknown.
Did you know?
Saarijärvi was found through geophysical surveys of the lake.
Microfossils in its fill show it is more than 600 million years old.
The crater lies in the forests of north-eastern Finland.