|How will the next Pangaea look like?
|Question Date: 2014-03-03|
This is a very good question! It is actually
impossible to predict what the next Pangaea or
supercontinent will look like, but we can make
some guesses. Today there are several large
continents that are separated by ocean basins.
Ocean crust grows at mid-ocean ridges and is
recycled back into the mantle at subduction
When ocean crust is recycled back into the mantle
faster than it grows at ridges, ocean basins
“close”, and continents come together to form
supercontinents. Today, the Pacific Ocean crust is
being recycled back into the mantle faster than it
is being created at a mid-ocean ridge (known as
the “East Pacific Rise”), so this ocean is
actually closing (Hamilton, 2007). The Atlantic
Ocean crust is being created at the “Mid-Atlantic
Ridge”, but it is not being recycled at any
subduction zones, so this ocean basin is growing.
I made cartoon cross sections of these two
to show what they might look like if you cut
across them and could look at the inside.
see that they have very different features. The
Pacific is surrounded by subduction zones,
the Atlantic doesn’t have any subduction occurring
at its edges. This means that the east coasts of
North and South America and the west coasts of
Europe and Africa won’t join in a supercontinent
any time soon. They are actually growing farther
apart as the Atlantic Ocean opens up between them.
On the other hand, the east coast of Asia and the
west coasts of North and South America may come
together many millions of years from now. If that
happens, the islands in the Pacific, like the
Marianas islands, the Philippines, and Japan will
be sandwiched in between. It would take a VERY
long time for the Pacific Ocean to fully close
though (many millions of years). Plate
(how the ocean and continent plates move on the
surface of the earth) is very complicated, so it
is impossible to predict if that will really
happen. There have been many supercontinents in
the history of the earth (Rodinia, Gondwana,
Pangaea). It is certain that new supercontinents
will form in tens or hundreds of millions of years
from now, but it is hard to predict what they will
Hamilton, W. B. (2007). Driving mechanism and 3-D
circulation of plate tectonics. Geological Society
of America Special Papers, 433, 1-25.
Good question. This is the subject of
speculation because it depends on where rifts form
and where the continents move in the next few
hundred million years. Most of the continents, all
except South America and Antarctica, are moving
north and colliding as they do so, thereby
creating a new northern continent in the process.
This new northern continent will have no
Mediterranean (because Africa will have closed
it), and Australia will have rammed into Southeast
Asia, and North America will have joined with
Eurasia both in the east (across the north
Atlantic) and in the west (Alaska-Siberia),
turning the Arctic Ocean into an inland sea.
However, South America will continue drifting
west, making it an island continent again as it
pulls free of North America, and Antarctica will
stay where it is for the foreseeable future.
However, unpredictable things happen. Eastern
Africa is currently rifting away into three
chunks: Arabia, which is colliding with Asia much
as India has, Sudan, which includes the entire
eastern side of Africa, and Tanzania, which is the
round-ish block including Lake Victoria, in the
center. They're all moving east (except Arabia,
which is moving north). However, there is an
example of a failed rift in North America that
would have torn North America apart roughly
through the location of the present-day state of
Missouri, but rifting stopped for some reason.
Will the African rift continue? And what new
rifts will form that might, for example, move
Antarctica off of the South Pole so that it can
interact with the other continents again? These
things we don't know how to predict - yet.
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