1. THE THEORY OF PLATE
TECTONICS’ - BOUNDARIES,
STRESSES,
AND FAULTS
PREPARED BY: Miss_Rona
2. S10ES – Ia-j-36.3
• Explain the different
processes that occur along
the plate boundaries
3. 1. WHAT IS THE THEORY OF PLATE
TECTONICS?
2. WHAT ARE THE THREE TYPES OF
PLATE BOUNDARIES?
4. WHAT ARE PLATES?
• The Earth’s crust and upper
mantle (Lithosphere) are broken
into sections called plates
A section of the lithosphere that slowly
moves over the asthenosphere, carrying
pieces of continental and oceanic crust.
Plates move around on top of the mantle like rafts
5. WHAT IS THE THEORY OF PLATE TECTONICS?
The theory that pieces of Earth’s lithosphere are in
constant motion, driven by convection currents in
the mantle.
• Plates move
slowly in
different
directions
❑Cause different
geologic events
(like
earthquake,
volcano, etc.)
6. WHAT MAKES THE PLATES MOVE?
Convection Currents in the mantle move the plates as the core heats
the slowly-flowing asthenosphere (the elastic/plastic-like part of the
mantle).
8. FAULT – BREAKS IN EARTH’S CRUST WHERE
ROCKS HAVE SLIPPED PAST EACH OTHER.
The edges of Earth’s
plates meet at plate
boundaries.
❖Extended deep into the
lithosphere
THERE ARE THREE TYPES OF PLATE BOUNDARIES!
Plate Boundaries
9. WHAT ARE THE THREE TYPES OF BOUNDARIES?
•Divergent Boundaries
•Convergent Boundaries
•Transform Boundaries
A different type of plate movement
occurs along each type of boundary.
10. DIVERGENT BOUNDARIES
A plate boundary where two plates move away
from each other.
RIFTING
causes
SEAFLOOR SPREADING
11. HOW IS THE ROCK PULLED AT DIVERGENT
BOUNDARIES?
ROCK GETS THIN IN THE MIDDLE AS IT IS
PULLED APART.
THIS STRESS IS CALLED
12. WHAT HAPPENS WHEN THE ROCK SNAPS
FROM THE STRESS OF TENSION?
A NORMAL FAULT (FAULT IS A BREAK IN
EARTH’S CRUST)
ROCK DROPS DOWN AS IT BREAKS
13. WHAT HAPPENS NEXT AT DIVERGENT BOUNDARIES?
• A geologic feature or event…
May form RIFT VALLEYS on
continents
SEA-FLOOR
SPREADING in the
ocean
14. HELPFUL HINTS…
• Divergent is like “dissecting” or “dividing”
• If you pull warm bubble gum or silly putty, it will thin in the
middle until it is stressed so much that it breaks.
• Happens on land
& under the ocean or water
16. CONVERGENT BOUNDARIES?
A plate boundary where two plates move
towards each other.
Boundaries between
two plates that are
colliding
This stress is called COMPRESSION
18. THERE ARE 3 TYPES OF CONVERGENT
BOUNDARIES…
Type 1
Ocean plate colliding with a less dense
continental plate
Subduction Zone: The process by which
oceanic crust sinks beneath a deep-ocean
trench and back into the mantle at a
convergent plate boundary.
22. TYPE 2
• Ocean plate colliding with another ocean plate
• The less dense plate slides under the denser
plate creating a subduction zone called a
TRENCH
24. TYPE 3
• A continental plate colliding with another
continental plate
• Have Collision Zones:
• A place where folded and thrust faulted
mountains form.
25. • May form Mountain Ranges.
These are Folded Mountains, like the Himalayas or
the Rockies.
26. WHAT HAPPENS WHEN THE ROCK IS SQUEEZED
FROM THE STRESS OF COMPRESSION?
•A REVERSE FAULT
• Rock is forced upward as it
is squeezed.
27. HELPFUL HINTS…
• Convergent = “Connecting” boundaries
• May work like a trash compactor smashing rock.
• Rock goes crunches up to make folded mountains.
• Rock goes down “under” @ subduction zone.
29. HOW IS THE ROCK BROKEN AT
TRANSFORM BOUNDARIES?
• Rock is pushed in
two opposite
directions (or
sideways, but no
rock is lost)
• This stress is
called SHEARING
30. WHAT HAPPENS NEXT AT TRANSFORM
BOUNDARIES?
• May cause
Earthquakes
when the rock
snaps from the
pressure.
• A famous fault @
a Transform
Boundary is the
San Andreas Fault
in California.
32. WHAT HAPPENS WHEN THE ROCK IS
SHEARED (OR “CUT”) FROM THE STRESS
OF SHEARING?
•A STRIKE-SLIP FAULT
•Rocks on each side of the fault slip
past each other as they break.
33. HELPFUL HINTS…
• Shearing means cutting (“Shears” are
like scissors)
• Transform boundaries run like trains
going past each other in different
directions & they shake the ground!
34. Can you match
the boundary
name correctly
with its diagram?
A._____________
B._____________
C._____________
PLATE BOUNDARIES:
