Alfred Wegener developed the continental drift theory after observing that continents seemed to fit together. He proposed that the continents were once joined together in a supercontinent called Pangaea, which later drifted apart to their current positions. Evidence for the theory included matching geological formations and fossil distributions across separated continents. The theory gained support with the discoveries of seafloor spreading and plate tectonics in the mid-20th century. Plates of oceanic crust continually move and interact at plate boundaries, providing a mechanism for continental drift over geologic timescales.

1. CONTINENTAL DRIFT THEORY

2. Alfred Lothar Wegener
 A German polar researcher, geophysicist,
and meteorologist.
 Developed a theory to explain his
observation that at one time all the
continents were a part of one large
landmass called PANGAEA.
 Suggested that the parts of Pangaea
drifted to their present position. He called
his idea as the CONTINENTAL DRIFT
THEORY.

3. Evidence of continental drift
theory
a. Geological Fit Evidence
b. Fossil Evidence

4. Geological “Fit” Evidence
 is the matching of large-
scale geological feature on
different continents.

5. Geological “fit” evidence
Same rock types different
continents.
Matching mountain chains different
continents.

6. Fossil Evidence
Fossil – are the remains or traces of plant or
animal life, usually preserved in rocks and
sedimentary.

7. Fossil evidence
 Same Fossils different continents
 Plant fossils in polar region
 Coal deposits in polar region

8. Mesosaurus
 is known to have been a type of
reptile, similar to the modern
crocodile, which propelled itself
through the water with its long
hind legs and limber tail.
Permian period (286 to 258 million
years ago),

10. Cynognathus
 was a mammal-like reptile as
large as a modern wolf.
Triassic period (250 to 240 million
years ago)

12. Lystrosaurus
 which translates to "shovel
reptile,"
 is thought to have been a
herbivore with a stout built like a
pig.

14. Glossopteris
 the most important fossil
evidence found in the plant,

17. SEAFLOOR SPREADING

18. Seafloor Spreading and Magnetic Reversal
The idea of continental drift circulated in
scientific circles until World War II, when
sounding gear called SONAR produced new
evidence of what the seafloor looked like. The
gear, developed in the 1930s, bounced sound
waves off the seafloor to determine its depth and
features.

20. The command of a attack
transport ship, the USS
Cape Johnson, was given
to Harry Hammond Hess,
a geologist from
Princeton university.

21. Seafloor Spreading
“Hot less dense material from below the
earth’s crust rises towards the surface at the
mid-ocean ridge.”

23. The place where two plates move apart or diverge
is called a divergent boundary.

25. from: http://www.geo.lsa.umich.edu/~crlb/COURSES/270
Continental crust to continental crust
collision
India-Asia (Himalayas)
Before collision
After collision

26. The Mid-Ocean Ridge system, shown above snaking its way between the continents, is more
than 56,000 kilometers (35,000 mi) long. It circles the earth like the stitching on a baseball!

27. A convergent
boundary is where
two plates come
together, or
converge. The
result of the plates
hitting together is
called a collision.

28. A transform
fault boundary is
a place where two
plates slip past
each other, moving
in opposite
directions.

29. Oceanic crust to oceanic

30. Also the way the Appalachian Mountains formed!

31. Because one plate gets pushed under
another, it is called subduction. This
is where volcanoes form!
Oceanic crust colliding
with oceanic crust
Oceanic crust colliding
with continental crust
all from: http://www.geo.lsa.umich.edu/~crlb/COURSES/270