By Sir Rahim-Ud-Din

2. A tectonic plate (also called lithospheric plate) is
a massive, irregularly shaped slab of solid rock,
generally composed of both continental and
oceanic lithosphere.

3. Plates are made of rigid lithosphere.
The lithosphere is made up of the crust and the upper
part of the mantle.

4. Below the
lithosphere
(which makes up
the tectonic
plates) is the
asthenosphere.

5.  “Plates” of lithosphere are moved around by the
underlying hot mantle convection cells

7. Proposed in 1911
All evidence found on the continents
Mechanism for moving the continents was not
known

8.  Alfred Wegener proposed
the hypothesis of
continental drift in 1911
 He gathered information
from many different
sources and used it as
evidence for his
hypothesis

9. Fit of the continents
Fossil evidence
Ancient mountain ranges
Past climate evidence
Glaciers formed at the south pole

10.  The continental
drift hypothesis
proposes that the
continents were
assembled to
form the super
continent
Pangaea.
 Moved through
time
3:20

11.  Antonio Snider-Pelligrini
(1858), a geographer cut
out a map of Africa and
South America suggesting
they were connected at one
time
 Other physical evidence
based on observation was
used by Wegener

12.  Similar terrestrial species were found on many
continents now separated by oceans.
 Information collected by paleontologists

13. The same sequence of rocks is found in North
America, Great Brittan, and Norway. The pattern does
not make sense with the continents in their current
configuration.

14. Swamps
300 million years ago

15. •Glaciers carve the rock as they move.
•Scientists can determine the direction of movement (notice the
direction of movement noted in South America)
•As South America sits today, the pattern would not make sense.
(glaciers do not move from sea level to higher elevations)

17. Divergent
Three types of plate boundary
Convergent
Transform

18. Continuing divergence
• Widening sea
• Mid-oceanic ridge system
• New crust formed at mid-oceanic ridge

19. During break up of a continent
• Rifting, basaltic eruptions (Flood Basalts),
uplifting
• Shallow focus earthquakes
Continental crust separates
• Oceanic crust created

24. Plates move toward each other
One plate overrides the other
• Subduction zone

26.  Oceanic-Oceanic Convergence
• Oceanic trench
 curved convex to subducting plate
• Benioff zone (Dipping 200-900; average 450)
• Magma generated at depth
 Andesitic volcanism
 Batholith emplacement
• Island arc
• Accretionary wedge forms (formed from
sediments that are accreted onto the non-
subducting tectonic plate at a convergent plate
boundary)
• Trench migration in time

27. Subducting Plate

29. Oceanic-Continental Convergence
• Active continental margin
 Subduction of oceanic lithosphere beneath
continental lithosphere
• Magmatic arc- volcanoes & plutons
• Crustal thickening and mountain belts
• Regional metamorphism
• Thrust faulting & folding on continental side

31. Continental-Continental convergence
• Two continents approach each other and
collide
 Sea floor subducted on one side
 Ocean becomes narrower and narrower
• Crust thickened
 Thrust belts
• Mountain belt in interior of continent

33. Boundary between two plates that are sliding
past each other
EARTHQUAKES along faults

34. San Andreas Fault, CA