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It is possible, however, that many of the Hopewell meteorites resulted from a single cosmic airburst event. The spatial distribution, contexts, and diverse composition of Hopewell meteorites has been explained as acquisition through long-distance exchange systems and trade networks 13, 14, 15, 16, 17. They include iron meteorites (e.g., ataxites, hexahedrites, octahedrites), stony iron meteorites (e.g., mesosiderites, pallasites), and stony meteorites (e.g., olivine hypersthene chondrites) 12. In the western Hemisphere, Hopewell archaeological sites in the Ohio River valley contain an anomalously high concentration and diversity of meteorites when compared to all other cultural periods. Comet airburst events produce meteorites, iron (Fe) and silicon (Si) rich microspherules, and positive anomalies of iridium (Ir) and platinum (Pt) 9.ДЄrchaeological evidence of ancient cosmic impact events has been recovered from archaeological sites of various ages in Europe, the Near East, and China 10, 11. If a comet fragment fell into the high-pressure air of earthвЂ™s thermosphere, an explosion, known as an airburst, would release a devastating high-energy shockwave over a large area resulting in burned agricultural fields, buildings, and forests as evidenced by the Tunguska event of 1908 8. In some cases, comets such as SL9 break apart and impact planets 7. At this time, human communities and the resources they needed for survival were at a heightened risk of being destroyed by a comet airburst event.Д¬omets are dirty fractured snowballs composed of cosmic dust, frozen gases, and meteoroids 6. Between 1,8В years ago (220 and 589 CE), Chinese astronomers documented 69 near-Earth comets (<вЂ‰1.3 au and a period of revolutionвЂ‰<вЂ‰200В years), including HaleyвЂ™s, which came within 0.09 au of earth in 374В CE (1646 B.P.) 5. andвЂ‰~вЂ‰3000 B.P.), and one in Jordan (~вЂ‰3,700 B.P.), suggests that these natural catastrophes are far more common than previously suspected 3, 4. The recent discovery of two Holocene cosmic impact events in Argentina (~вЂ‰6000 B.P. Both of these events are associated with global mass extinctions and they occurred before humans culturally evolved into complex, sedentary, agricultural-based societies. Direct positive evidence of catastrophic cosmic airburst and impact events have been found in the Western Hemisphere at the Cretaceous and Tertiary (KT) boundaryвЂ‰~вЂ‰65 million years ago and at the Younger Dryas (YD) boundaryвЂ‰~вЂ‰12,800В years ago 1, 2.

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