Embedded iron particles surrounded by carbonized
rings in the outer layer of a mammoth tusk from
Alaska. Inset photo shows how an object ripped
through the tusk.
Image courtesy Richard Firestone.
This column is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. Ned Rozell is a science writer at the institute.
A giant meteor may have exploded over Alaska thousands of years ago, shooting out metal fragments like buckshot, some of which embedded in the tusks of woolly mammoths and the horns of bison.
Simultaneously, a large chunk of the meteor hit Alaska south of Allakaket, sending up a dust cloud that blacked out the sun over the entire state and surrounding areas, killing most of the life in the area.
Such is the scenario envisioned by Rick Firestone, a staff scientist at the Lawrence Berkeley National Laboratory in California. Firestone and his colleagues have found mammoth tusks and a bison skull with nickel-rich iron particles in them on one side, suggesting the metal fragments all came from the same direction.
Firestone’s theory emerged when his colleague, Alan West of Dewey, Arizona, saw at a Phoenix gem and mineral show a mammoth tusk peppered with tiny bits of metal.