America and Eurasia 'to meet at north pole'By Neil Bowdler Science and health reporter, BBC News
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America and Eurasia will crash into
each other over the north pole in 50-200 million years time, according to
scientists at Yale University.
They predict Africa and Australia will join the new "supercontinent" too,
which will mark the next coming together of the Earth's land masses.
The continents are last thought to have come together 300 million years ago
into a supercontinent called Pangaea.
The land masses of the Earth are constantly moving as the Earth's as tectonic
activity occurs. This generates areas such as the Mid-Atlantic Ridge, where
Iceland has formed, and areas such as that off the coast of Japan, where one
plate rides over another.
Geologists believe that, over billions of years, these shifting plates have
driven the continents together periodically, creating the hypothesised
supercontinents of Nuna 1.8 billion years ago, Rodinia a billion years ago, and
then Pangaea 300 million years ago.
The next supercontinent has already been given the working title of Amasia,
as it is expected to involve the convergence of the Americas and Asia.
What the researchers have set out to do is predict when and where it will
form by looking back at where its predecessors emerged.
"We're all pretty familiar with the concept of Pangaea, but there hasn't been
much convincing data to suggest how the supercontinents take shape," Ross
Mitchell of Yale University told BBC News.
"In our model, we actually have North America and South America joining by
closing the Caribbean Sea and the Arctic Sea closing and connecting the Americas
and Asia."'Better insight'
The model puts the repositioned Americas within what is known as the Pacific
"ring of fire". Europe, part of the Eurasian land mass, Africa and Australia are
predicted to join the merging continent, with only Antarctica left out.
The prediction is based on analysis of magnetic data locked into rocks around
the world which betray the magnetic orientation of those rocks in past ages.
An animation showing plate motions for the past 500 million
years and the rise and fall of the previous supercontinent Pangaea
"Ancient rocks when they form, whether it's lava cooling or sedimentary rock
solidifying, will lock in the magnetic orientation," explained Mr Mitchell. "But
while this indicates latitude very accurately, historically we haven't had
indicators of longitude.
"We found that after each historical supercontinent had assembled, this whole
supercontinent would undergo a series of back-and-forth rotations about a stable
axis on the equator."
This led them to the view that that each successive supercontinent forms 90
degrees away from its predecessor. Previous studies have suggested
supercontinents would form either in the same part of the globe or on
alternating sides of the globe.
Commenting on the paper, Dr David Rothery, a geologist with the Open
University, said the new research offered us a better insight into the history
of our planet.
"We can understand past environments better if we know exactly where they
were," he told BBC News. "I don't think as a European I care whether continents
are going to converge over the North Pole or whether Britain crashes into
America in the far future. Predicting into the future is of far less concern
than what happened in the past."
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