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No Safe Ground For Life To Stand On During Largest Mass Extinction

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  • Pat Neuman
    No Safe Ground For Life To Stand On During Largest Mass Extinction London, UK (SPX) Dec 01, 2005 The world s largest mass extinction was probably caused by
    Message 1 of 1 , Dec 1, 2005
      No Safe Ground For Life To Stand On During Largest Mass Extinction

      London, UK (SPX) Dec 01, 2005
      The world's largest mass extinction was probably caused by poisonous
      volcanic gas, according to research published today.
      The research, published in the journal Geology, reveals vital clues
      about the mass extinction at the end of the Permian period, 250
      million years ago, when mammal-like reptiles known as synapsids
      roamed the earth.

      Many scientists had previously thought that an asteroid hitting the
      earth or a deep-sea methane release had caused the extinction, which
      obliterated more than two-thirds of reptile and amphibian families.

      However, analysis of a unique set of molecules found in rocks taken
      from the Dolomites in Italy has enabled scientists to build up a
      picture of what actually happened. The molecules are the remains of
      polysaccharides, large sugar-based structures common in plants and
      soil, and they tell the story of the extinction.

      The molecules date from the same time as a major volcanic eruption
      that caused the greatest ever outpouring of basalt lava over vast
      swathes of land in present day Siberia.

      The researchers believe that the volcanic gases from the eruption,
      which would have depleted earth's protective ozone layer and
      acidified the land and sea, killed rooted vegetation. This meant
      that soil was no longer retained and it washed into the surrounding

      The chemistry of the rocks reveals that although the sugar molecules
      were found in marine sediments, they derived from land, supporting
      the theory that massive soil erosion caused them to end up in the

      Soil materials in the oceans would have blocked out light and soaked
      up oxygen. Analysis of rock chemistry suggests that after the soil
      crisis on land, the marine ecosystem succumbed to the stresses of
      environmental change and oceanic life faltered, completing a global

      Dr Mark Sephton, from Imperial College London's Department of Earth
      Sciences and Engineering and lead author of the research, said: "The
      cause of the end Permian extinction has been highly controversial.
      We show that the terrestrial ecosystem was the first to suffer. The
      continent-wide nature of the event implies that it was caused by
      something in the atmosphere. The unique chemical data indicates that
      something fast and catastrophic happened on land."

      Prof Henk Visscher of Utrecht University, also part of the research
      team, commented: "Similar to the 'Dead Zone' nowadays spreading in
      the Gulf of Mexico, the soil crisis could have caused a worldwide
      expanse of uninhabitable low-oxygen conditions in shallow marine
      waters. So what began on land ended in the sea. It seems there was
      no place to hide at this time of great dying."

      Dr Sephton believes that lessons can be learned in the present day
      from the damage caused by the end Permian extinction: "Land
      degradation is a worsening global problem thanks to human activity
      and soil erosion has caused the loss of a third of arable land over
      the last forty years. 35% of the Earth's land is now soil-free.
      Identifying the nature of the end Permian soil crisis may help us
      understand what is in store for us in the years ahead," he said.

      The research was carried out by an international team of scientists
      from the United Kingdom, the Netherlands and the United States.

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