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Abundance peaks in microscopic materials, including meltglass, microspherules, Ni, Ir, and Pt have been found in Native American Hopewell-age cultural strata. This discovery includes micrometeorites (possibly pallasites) recovered from heavily burned strata in two Hopewell villages. This evidence suggests that a prehistoric cosmic airburst/impact event occurred in the Ohio River valley. The peaks in these exotic materials only occur within a dark, charcoal-rich burn layer containing a wide range of Hopewell artifacts, and they are not found above or below the layer.