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Panama:
Isthmus
that
Changed
the World
Twenty
million
years ago
ocean
covered
the area
where
Panama is
today,
creating a
gap
between
the
continents
of North
and South
America
through
which the
waters of
the
Atlantic
and
Pacific
Oceans
flowed
freely.
Beneath
the
surface,
two plates
of the
Earth's
crust
slowly
collided
into one
another,
forcing
the
Pacific
Plate to
slide
slowly
under the
Caribbean
Plate. The
pressure
and heat
caused by
this
collision
led to the
formation
of
underwater
volcanoes,
some of
which grew
tall
enough to
break the
surface of
the ocean
and form
islands as
early as
15 million
years ago.
More and
more
volcanic
islands
filled in
the area
over the
next
several
million
years.
Meanwhile,
the
movement
of the two
tectonic
plates
also
pushed up
the sea
floor,
forcing
some areas
above sea
level.
Over time,
massive
amounts of
sediment
were
peeled
away from
the
Americas
by strong
ocean
currents
and fed
through
the gaps
between
the newly
forming
islands.
Over
millions
of years,
the
sediment
deposits
added to
the
islands
until the
gaps were
completely
filled. By
about 3
million
years ago,
an
isthmus,
narrow
strip of
land with
water on
either
side, had
formed
connecting
North and
South
America.
The
formation
of the
Isthmus of
Panama
also
played a
major role
in
biodiversity,
making it
easier for
animals
and plants
to migrate
between
the
continents.
For
instance,
in North
America
today, the
opossum,
armadillo,
and
porcupine
all trace
back to
ancestors
that came
across the
land
bridge
from South
America.
Likewise,
the
ancestors
of bears,
cats,
dogs,
horses,
llamas,
and
raccoons
all made
the trek
south
across the
isthmus.
Scientists
made this
false-color
image of
Panama
using data
acquired
in
February
2000 by
the
Shuttle
Radar
Topography
Mission,
flying
aboard the
Space
Shuttle
Endeavor. |
