The age of the Kaali meteorite craters and the effect of the impact on the environment and man: evidence from inside the Kaali craters, island of Saaremaa, Estonia

The Kaali meteorite impact crater field, which consists of a 110 m diameter main crater and eight satellite craters on the island of Saaremaa, Estonia is a unique object as its meteoritic origin is well proven, it lies in a densely populated area and fell in the relatively recent past. The precise age of the impact that generated the craters is still disputed. We investigated the basal sediment section from the main crater lake, Kaali järv, consisting of crushed and in-washed dolomite diamiction. AMS dating of terrestrial macrofossils from these sediment layers places the age of the impact at 1690−1510 B.C. The age is about 1000 years older than revealed from the impact marker-horizon in a contemporaneous peat sequence 6 km northwest of the Kaali crater. The pollen, diatom and chemical data suggest the instant formation of a shallow hard-water lake environment in the main crater depression after the impact, and a rapid post-impact sedimentation of crushed dolomite dust. Archaeological evidence on the crater slopes points to human activity around 700–200 B.C., indicating that the crater ring wall was inhabited by Bronze Age people soon after the impact event, and the structure of the main crater is mimicked in nearby archaeological sites.