Land Mass Distribution
Date: Prior to 1993
If the Earth formed out of the primordial gas cloud, one would
expect that the continents would be dispersed in a balanced configuration as
the Earth cooled. However modern theory places them together in a large land
mass or "supercontinent," seemingly in an out of balanced state. How did this
Wonderful question! I am going to quote from two texts ["Pangaea"
is the name given to the "supercontinent" which, it is believed, broke apart
over 200 million years ago, into pieces which drifted apart and became the
present-day continents]: From "The Solar System" by Encrenaz and Bibring, p.
135: "It is now possible to follow the history of the destruction of Pangaea
and geological evolution that was a result. On the other hand, we have hardly
any information about the continents that existed before that phase when there
was just one: did Pangaea appear as a result of the incessant movement of the
continents, shortly before the break-up, or had it existed as a stable entity
for thousands of years? From what we know of the causes of continental drift,
the first possibility seems more likely." From "Exploration of the Universe"
by Abell, Morrison, and Wolff, pp.262-3: "If we extrapolate the plates' motion
backward we arrive, some 200 million years ago, at the supercontinent of
Pangaea... The configuration of the continents before Pangaea is less well
understood. It is clear that plate tectonics were at work, from the existence
of old mountains (such as the Urals in the U.S.S.R. and the Appalachians in
the U.S.) that were formed more than 200 million years ago. Recent studies
indicate that plate tectonic activity in what is now North America can be
traced back 1.5 billion years." In other words, it is believed that Pangaea
was not the original land-mass configuration, but there are no guesses about
how it came to be.
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Update: June 2012