Ecological catastrophe in connection with the impact of the Kaali meteorite about 800-400 BC on the island of Saaremaa, Estonia

A sequence of peat enriched with impact ejecta (allochthonous minerals and iridium) from Piila bog, 6 km away from the Kaali impact crater (island of Saaremaa, Estonia), was examined using pollen, radiocarbon, loss-on-ignitio n, and x-ray diffraction analyses to date and assess the environmental effe ct of the impact. The vegetation in the surroundings of the Piila bog befor e the Kaali impact was a fen surrounded by forest in natural conditions. Si gnificant changes occur in pollen accumulation and composition of pollen in the depth interval 170-178 cm, which contains above background values of i ridium (up to 0.53 ppb). Two samples from the basal silt layer inside the m ain crater at Kaali contain 0.8 ppb of iridium, showing that iridium. was p resent in the impact ejecta. The impact explosion swept the surroundings cl ean of forest shown by the threefold decrease in the total pollen influx (e specially tree pollen influx), increase in influx and diversity of herb tax a, and the relative dominance of pine. Increased input of mineral matter me asured by loss-on-ignition and the composition mineral matter (increased in put of allochthonous minerals) together with an extensive layer of charcoal and wood stumps in Piila bog at the same depth interval points to an ecolo gical catastrophe, with local impact-induced wildfires reaching at least 6 kin northwest of the epicenter. The disappearance of cereals in the pollen record suggests that farming, cultivation and possibly human habitation in the region ceased for a period of similar to 100 years. The meteorite explo sion at Kaali ranged between the effects of Hiroshima and Tunguska. The age of the Kaali impact event is placed between 800-400 B.C. based on radiocar bon dating of the peat enriched with impact ejecta in the Piila bog.