Archaeological discoveries

Did a meteorite destroy the settlement of Asva during the Bronze Age?

Estonia was thought not to be significantly developed during the Bronze Age due to a general shortage of pieces. However, the discovery of numerous remains in the first excavations of the fortified hill of Asva in the 1930s it revealed a whole culture unknown until then. Archaeological evidence showed a stratified agrarian society with the existence of metallurgical workshops in fortified settlements that suggested control of metal production and technology, with Asva and other similar sites being the main sites of a whole network of constructions. In addition, they presented a specific ceramic typology different from that of the neighboring Latvian or Lithuanian fortifications, and which suddenly disappears from the records with the decline of this type of settlement. In the case of Asva, the existence of a 30 cm stratum formed by charred remains has been confirmed, which can be considered indicative of a fire of great intensity and extension.

Is there a relationship between the meteorite that created the Kaali crater and the destruction of Asva? Based on the trail left, it has been estimated that it was a body of up to 1000 tons , striking at an angle of 35º and which, due to friction with the atmosphere, fragmented into several pieces. The largest of approximately 450 tons impacted at 15 km/s creating the Kaali crater with a diameter of 105-110 m and 16 m deep. The remaining fragments created another eight satellite craters between 12 and 14 m in diameter and up to 4 m deep. The total energy released was equivalent to about 20 kilotons of TNT, on the same order as that caused by the Hiroshima atomic bomb.

It is possible to estimate its effects compared to similar events. The Tunguska event it was three orders of magnitude larger, but since the explosion of its meteorite took place at a height of 5-10 km, the shock wave that reached the ground produced an earthquake of magnitude 4.5, with an energy of 5-32 kilotons of TNT , therefore comparable to the Kaali event. In Tunguska there was a devastation of 2,100 square km of forest and a radial fire of more than 100 square km. The Hiroshima bomb, on the other hand, produced smaller, more circular devastation, with collapse of buildings up to a radius of 8 km and ignition of dry combustible material up to a distance of 3 km from the epicenter.

It can be considered that the damage caused by the meteorite in Kaali would be of the same magnitude . It would induce forest fires up to a considerable distance from the point of impact, and it is likely that their spread would even reach Asva, although it was 20 km from the crater. Once this geographical coincidence has been established, in order to correlate the fall of the meteorite and the disappearance of Asva, it is necessary to establish the date of the impact. Different techniques have been used by researchers but there is still no real consensus on which of the values ​​obtained is the one that should be considered correct.

As Veski summarizes, in 1794 Rauch considered the crater to have a volcanic origin, and it was not until 1928 that a meteoritic origin was suggested and the dating debate began. Linstow (1929) estimated an age of 8000-4000 BC, and in 1938 Reinwald proved the origin by collecting meteoritic iron fragments and proposed that the craters were not too old, considering them post-ice age. Aaloe (1958) concluded that they should have been formed when that coastal area was already emerged as marine sediments were not found in them, giving a date of 3000-2500 BC, although years later (1963) he analyzed by radiocarbon samples of wood and charcoal from craters and gave a date of 1100-600 B.C. Kessel estimated in 1981 an impact date of 1800 BC. analyzing the pollen in the sediments.

Another radiocarbon dating of the sediments (Saarse et al, 1991) gave a value of 1740-1620 BC, but was criticized because they were not collected from the bottom of the flooded lake of water the crater. Raukas (2003) measured wood samples obtained from the slope giving a date of 790-390 BC. Rasmussen (2000) and Veski (2004) made pollen measurements, giving a figure of 1690-1510 BC. but at the same time they questioned the radiocarbon dating of material from the flooded interior of the crater for presenting material contamination.

Several researchers made an indirect measurement from surrounding peat bogs that received material ejected during the collision. Crystalline silica microspherules were found in the Piila peat bog 6 km away and radiologically dated to 6400 BC, and similar microspherules have been found in other peat bogs nearly 70 km to the north. Review of the island's geological history allows this date to be ruled out as invalid since the Baltic Sea level was then 16 m above the current level and the crater would have been filled with salt water, not fresh. In addition, the ejection of material at that distance is not considered possible for the magnitude of the Kaali event, so it has been concluded that they must come from another much earlier event.

On the other hand, in the Piila peat bog, a stratum with a high content of Iridium dated to 800-400 BC has been found at a depth of 172-177 cm. and associated with it is a scorched layer indicating that the bog suffered a major fire. The analyzes indicate for this stratum up to three orders of reduction in tree pollen and as well as a disappearance of pollen from cultivated cereals.

As can be seen, the different radiocarbon datesgive conflicting dates . Although there are disturbances due to the removal of sediments when a pavilion was built in the lake, the most probable cause, as Rasmussen indicates, may be that the ground that suffered the impact is Silurian dolomitic rock, with a high carbon content and that, when fragmenting and spraying increased the presence of lime in the water. This would explain why radiocarbon dating in the crater and its surroundings on samples that have been contaminated by this hard water show a much older age than it really corresponds to.

Microspherules ruled out as unrelated, and given that any dating of samples from the lake or crater may be considered dubious due to the possibility that they are contaminated by carbon released from bedrock lower dolomitic, more weight should be given to evidence based on another indicator. In this case, iridium is extremely rare in the earth's crust but it is common in metallic meteorites, so its presence must be considered as due to deposition from an extraterrestrial origin.

If the date established by the level of iridium in the Piila bog of 800-400 BC is accepted, there is temporal agreement with the period in which there is practically no archaeological remains and animals in Asva (middle of the first millennium BC), with the period of tree pollen reduction, and with the dating of the charred remains of Asva (685-585 BC), so it is very plausible that everything would have happened in the same time frame, indicating an abrupt end to what is considered the westernmost manifestation of Hungarian-Finnish Bronze Age culture .

This article is part of the 1st Desperta Ferro Historical Microessay Contest. The documentation, veracity and originality of the article are the sole responsibility of its author.