terça-feira, 28 de maio de 2013
Scientists Challenge Theory of Massive Comet or Meteorite Hit to Wipe out Mammoth
A 16-member research team from the United States, Britain and Belgium has challenged the hotly disputed theory that a massive comet or meteorite struck a glacier-encased Hudson Bay about 13,000 years ago.
The theory suggested that the impact was so strong that it wiped out the mammoths and other Ice Age megafauna. Moreover, it destroyed the first major wave of human migration in the new world.
The research team published their major study in February and said that there us a lack of clear evidence to prove that a four-kilometer-wide comet exploded across the Laurentide Ice Sheet that covered ancient Canada.
"No impact craters of the appropriate size and age are known and no unambiguously shocked material or other features diagnostic of impact have been found to prove the theory", the authors stated in monograph published by the American Geophysical Union
They said that the proponents are trying to explain the climatological, paleontological and archeological events that are not unique and do not require and impact. For example, layers of so-called shocked rocks and minerals are suggested by the theory to have transformed by an earth-shaking mega-blast.
However, a team of 29 scientists from the U. S., Mexico, the Netherlands, Germany and the Czech Republic contradicted the February findings in a new, pro-impact study published online in the Proceedings of the National Academy of Sciences.
Publicado por Jorge M. Gonçalves às 5:30 da tarde