Continental Drift
Key terms
continental drift: The theory that the continents were once one landmass but that they have
drifted apart over time
• Changes in the position of continents over time.
• It is believed that all the continents used to be joined and forming one big continent.
• It was called Pangaea.
• Pangaea then split into two forming Laurasia and Gondwana.
• Surrounded by one worldwide super-ocean called Panthalassa
• Gondwana eventually also broke up into South America, Africa, Australia, Madagascar,
Antarctica and India
• Plate tectonics: theory about the movement of crustal plates
Changes in the position of continents
• In 1912, a German scientist called Alfred Wegener said that the continents were
once all joined in a single landmass.
• He called the single landmass Pangaea, which is Greek for ‘all land’.
• Alfred Wegener, a German meteorologist, who is given total credit for his
detailed theory of the breakup of a single super-continent and the drifting apart
of the individual continents.
• He is known as ‘the father of continental drift theory’.
Notice that Pangaea split
into two separate land
masses called Laurasia and
Gondwanaland. The
continents continued to
move until they looked like
today’s map of the world
Changes in the position of continents
• All the continents appear to fit neatly together, like a jigsaw puzzle.
• This was what made Wegener think that maybe they really were
joined together at one time and then something caused the
continents to drift apart over time.
• He called his ideas the theory of continental drift.
• In his theory, Wegener suggested that about 200 million years ago,
the map of the world would have looked something as in.
Evidence for movement of the
continents
• Rocks of similar type, age and formation are found in south-east
Brasilia and South Africa, suggesting Africa and South America used to
be joined.
• The continents fit together like a jigsaw puzzle.
• Coal, which forms in hot and wet conditions are found beneath the
Antarctic ice cap.
• Fossils of similar small reptiles were found in south-east Brasilia and
South Africa.
Evidence continues…..
• Glaciers that covered large parts of the continents in the southern
hemisphere in the Palaeozoic Era moved in the same direction.
• Glaciers are masses of ice with limited width that move outward
from an area of accumulation. They are slow moving large rivers
of ice.
• Fold mountain systems are said to be linked with floating
continents.
• The Rift Valley of Africa shows that Africa is slowly splitting into
two.
fossils
 The discovery of Mesosaurus fossils
in both Africa and South America
proved that these two continents
had once been joined. Scientists also
found fossils of the Lystrosaurus in
Antarctica, southern Africa and
India.
 Like the Mesosaurus, Lystrosaurus
was a land animal, so this was
further proof that the continents
were once joined at the time these
animals lived.
Mountain ranges
When geologists plotted the
positions of old mountain
ranges on the map of
Pangaea, they found that
these mountain ranges all
lined up.
They also found that the
mountains were formed of
rocks of the same type, age
and structure.
Sea-floor spreading
 The Atlantic Ocean did not exist when the
continents were joined together.
 Once the continents started to move apart,
the Atlantic Ocean appeared and has been
getting wider ever since.
 We call this ocean floor spreading, New
land is constantly forming along the midAtlantic sea floor.
 Geologists have found rocks of the same
age and type on either side of the midAtlantic.