karl_lembke (karl_lembke) wrote,
karl_lembke
karl_lembke

When continents collide

A repost from the Informed Reader blog at WSJ:


October 17, 2007, 6:10 pm

When Worlds Collide, What Will Emerge?


Scientists believe that the Earth's continents will collide again in
around 250 million years, but there is no consensus on just how the land
masses will come together. One thing is clear, though: Humans, who will
probably be extinct by then, wouldn't want to live in the world that
emerges anyway.

The way continents travel across the earth's crust means that every 500
to 700 million years, the land masses form a supercontinent for a few
hundred million years before breaking apart again. The last
supercontinent, known as Pangea, existed between 100 million and 300
million years ago. Scientists believe there was an earlier
super-continent that formed 1.1 billion years ago (dubbed Rodinia), and
they speculate about ones earlier than that.




How the continents might appear in 250 million years, in a rendering by
Prof. Christopher Scotese


The continents are half-way to another collision, moving at roughly the
speed that fingernails grow, report science journalists Caroline
Williams and Ted Nield in New Scientist
<http://environment.newscientist.com/channel/earth/mg19626261.500-pangae> . Since the 1990s scientists have developed two
competing hypotheses about how the continents might next fit together.
One school of thought sees the Americas pivoting around Siberia and
slamming into Asia. Australasia would travel northward to join the
clump. An alternative theory, put forward by Christopher Scotese, a
professor of geology of the University of Texas at Arlington, predicts
that in 200 million years the continents' paths will be upset by
tectonic plates colliding. That will cause the Atlantic to shrink and
draw North America into a European-African continent, one with a
Himalayan mountain range where southern Europe is today.

Either way, the new supercontinent wouldn't be a fun place to live for
most plants and animals. "The formation of Pangea has been implicated in
the greatest species loss of all time," the authors say, mostly due to
the loss of habitats. Most of the future supercontinent would be desert,
since no rain would develop over the vast interior. On the coasts
between the tropical latitudes, the weather would vary from 110 degrees
Fahrenheit in the summer to minus 4 degrees in the winter, punctuated by
hurricanes 50% stronger than the fiercest ones today. - Robin Moroney
OB-AS260_IR_BLO_20071017172813.gif

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