Transcript Pangea

Pangea
How It All Began
 Looking at a globe reveals coincidences that
are difficult to ignore. The Eastern coast of
South America seems to fit perfectly, almost
like a puzzle, into the Western coast of
Africa. At the same time, North America can
be rotated slightly, and made to fit
comfortably next to Europe, and Asia.
 These clues have lead geologists and other
scientists to examine the relationships of
other clues. Ancient fossil records show that
the same plants and animals lived along the
Eastern coast of South America, as did
along the Western coast of Africa, as did
other plants and animals along the coasts of
North America and Europe.
With this over whelming evidence, it became clear
that at some point many millions of years ago, these
continents must have in fact been connected.
 Scientists now believe that about
250 million years ago, a
supercontinent known as Pangaea
existed.
 This supercontinent was made up
of all the continents on Earth.
 Over time, these continents have
broken apart, and slowly drifted
away from one another.
 Pangaea was created when all the continents we
know today smashed together like some giant car
wreck.
 This crashing together was not a gentle process.
The Appalachian Mountains in North America and
the Ural Mountains on the boundary of Europe and
Asia are the results of some of these collisions.
 If you lived at the time of Pangaea, you could walk
from the North Pole to the South Pole without
getting your feet wet... well, unless you had to
wade in a river or something.
 Pangaea started to break up into the continents
that we know now during the middle of the
Jurassic time period, about 175 million years ago.
 Have you ever noticed that the east coast of South
America and the west coast of Africa look like they
could fit together like a giant jig saw puzzle? That's
because they used to be stuck together. At one
point North America, Greenland and Europe were
all connected; because North America and Europe
were connected, you can find the same rock
formations in New York and in Scotland
 The rifting of Pangaea started with North
America and Africa, and rifting continues on
the east side of Africa near the Red Sea in
an area called the Great Rift Valley.
 The land mass that would become North
America was twisted so that the Mississippi
River Valley would have been running east
and west, not north and south. In fact, the
Mississippi River Valley is the result of a
failed rift.
 North America and Africa tried to split apart
along what we now call the Mississippi River
Valley. When North America finally rifted
away from Africa, it formed the beginning of
what is now the Atlantic Ocean.
 The continents wouldn't reach their current
arrangement until 35 million years ago when
India crashed into Asia forming the
Himalayan Mountains.
 Pangaea took a really long time to crash
together (340 million years), was really big,
and took a really long time to break apart
(140 million years). Did you know that in
about 250 million years all the continents will
have crashed together forming another
supercontinent? Scientists already have a
name for the new supercontinent. They are
calling it Pangaea Ultima.
Thinking Question
 What force on Earth could possibly have
enough energy to cause the continents to
move as far as they have?
Vocabulary
Plate-rigid blocks of crust and upper
mantle rock.
These plated move in three ways:
• Toward each other - convergent
• Away from each other - divergent
• Sliding past each other - transforming
Destructive Zone
Subduction
Divergent
Convergent
Plate Techtonics
 Using modern equipment, scientists known
as oceanographers have been able to
measure and map out the ocean floor. What
these scientists have discovered has helped
explain how it is that continents are able to
move around on the Earth’s crust.
 Located deep beneath the waves on the
ocean floor almost exactly halfway between
the continents are raised areas known as
ridges. These ridges are similar to underwater mountain ranges. At other locations
we find extremely deep trenches, some
reaching many thousands of feet in depth.
 Many scientists believe that the ridges
represent areas where new crust is being
formed as hot magma escapes from the
Earth’s core and spreads outward. As the
seafloor spreads outward away from the
area where magma is being released, the
continents are carried across the sea, riding
on top of the sima crust.
 Geologists refer to this process as plate
tectonics. As we study plate tectonics, a
picture emerges of very old continents riding
on top of much younger and ever moving
plates. These plates move extremely slowly,
at a rate of only about 10 cm per year.
 http://www.kidsgeo.com/geology-forkids/0044-plate-boundaries.php
 http://www.teachertube.com/viewVideo.php?
video_id=230989