Evidence of mammoths and other megafauna and early human hunters, known as the Clovis culture, are found beneath the black mat but are missing entirely within or above it. This led the research team to conclude an extraterrestrial impact wiped out many of the inhabitants of the Late Pleistocene. Bunch notes that some animals may have survived in protected niches.
The black mat was formed by ponding of water and algal blooms and contains carbon, soot and glassy carbonremnants of burned materials. Some of these remnants are extraterrestrial in nature. For example, the research team has identified fullerenes, spherical carbon cages resembling a soccer ball, which are formed in shock events outside the Earths atmosphere. Trapped inside the fullerenes is a concentration of helium 3 that is many times greater than what is found in the Earths atmosphere.
The black mat also has turned up nanodiamonds, which are formed in the interstellar medium outside the solar system, by or by a high-explosive detonation.
Either these things came in with the impactor or they were made during impact detonation. We have no other explanation for their presence, Bunch said.
The magnitude of the detonations would have been huge.
A hydrogen bomb is the equivalent of about 100 to 1,000 megatons, Bunch said. The detonations were talking about would be about 10 million megatons. Thats larger than the simultaneous detonation of all the worlds nuclear bombs past and present.
The research team believes the detonations destabilized a vast ice sheet, known as the Laurentide Ice Sheet, that covered most of what was then Canada and the northern United States. Heat from the detonation and firestorms would have melted much of the
|Contact: Lisa Nelson|
Northern Arizona University