Kaali is a group of 9 meteorite craters in the village of Kaali on the Estonian island of Saaremaa. Most recent estimates put its formation shortly after 1530–1450 BC. It was created by an impact event and is one of the few impact events that has occurred in a populated area.
The craters were formed by a meteor with an estimated impact velocity of between 10 and 20 km/s with a total mass of between 20 and 80 metric tonnes. According to some researchers the meteor arrived from the north-east.
At an altitude of 5–10 km, the meteor broke into pieces and fell to the Earth in fragments, the greatest of which produced a crater with a diameter of 110 m and a depth of 22 m. The explosion removed approximately 81,000 cubic meters of dolomite and other rocks and formed a 7–8 km tall, extremely hot gas flow. Vegetation was incinerated up to 6 km from the impact site.
Kaali Lake (Estonian: Kaali järv) is on the bottom of this crater. Eight smaller craters are also associated with this bombardment. Their diameters range from 12 to 40 meters and their respective depths vary from one to four meters. They are all within one kilometer of the main crater.
The coolest thing about this crater was the bronze age community that may have sprung up around it. There's archaeological evidence of a large wall that was constructed around the ring of the crater. And still to this day the lake holds spiritual significance throughout livonia, and there's evidence of ritual sacrifice here dating back thousands of years. Why would people be drawn here? Well in the late bronze age people hadn't worked out iron smelting yet, so the only source of highly valuable iron was meteoric iron, which was traded across the continent. This would explain why so little remains of the original meteorite have been found - perhaps it was all extracted by bronze age miners.
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-ignition, and x-ray diffraction analyses to date and assess the environmental effect of the impact. The vegetation in the surroundings of the Piila bog before the Kaali impact was a fen surrounded by forest in natural conditions. Significant changes occur in pollen accumulation and composition of pollen in the depth interval 170–178 cm, which contains above background values of iridium (up to 0.53 ppb). Two samples from the basal silt layer inside the main crater at Kaali contain 0.8 ppb of iridium, showing that iridium was present in the impact ejecta. The impact explosion swept the surroundings clean of forest shown by the threefold decrease in the total pollen influx (especially tree pollen influx), increase in influx and diversity of herb taxa, and the relative dominance of pine. Increased input of mineral matter measured by loss-on-ignition and the composition mineral matter (increased input of allochthonous minerals) together with an extensive layer of charcoal and wood stumps in Piila bog at the same depth interval points to an ecological catastrophe, with local impact-induced wildfires reaching at least 6 km 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 ∼100 years. The meteorite explosion 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 radiocarbon dating of the peat enriched with impact ejecta in the Piila bog.