1. In your own words describe Continental Drift Hypothesis
How did Wegener support his hypothesis?
Why do you think he chose this type of information?
Why was the continental drift hypothesis rejected?
What is the difference between the Theory of Continental Drift and the Theory of Plate Tectonics?
Continental Drift was proposed first and only states (but does not explain) the splitting up of Pangaea in the current seven continents. Plate Tectonics explains Continental Drift, and also other geologic features such as volcanoes, earthquakes, mountains etc,
(c) McGraw Hill Ryerson 2007

2. III. Layers of the Earth Crust Mantle Core
Existence of volcanoes, earthquakes, mountains, indicates Earth is not solid rock.
Scientists believe earth began a s a molten ball over 4.5 billion years ago. As it cooled, lighter materials floated to surface, heavier sank inward to interior. Gravy fat.
Earth is over 1200 km thick and has four distinct layers: crust , mantle (upper and lower), outer core, and inner core.
Crust – outer solid rock layer (granite on land, basalt in oceans)
Mantle – thickest layer, mostly solid except for upper mantle being able to flow like “thick toothpaste”
Outer core – composed of liquid iron and nickel
Inner core – mostly solid iron, at tremendous temperature and pressure
Tectonic plates make up the lithosphere, which floats on the asthenosphere. The lithosphere is the crust and upper portion of the upper mantle.
The asthenosphere is the molten layer of the upper mantle.
Heat to keep the asthenosphere molten comes from radioactive elements.
Compare to a peach

3. Crust Outermost layer, relatively solid, brittle rock layer
Continental crust
approx. 50 km thick
made from less dense type of rock called granite
Oceanic crust
approx. 10 km thick
made from dense rock called basalt
Lighter materials formed crust (mostly silicon and oxygen.

4. Mantle Thickest layer: 2900 km thick Iron, magnesium and silicon
Upper Mantle: solid, more cool and brittle
Lower Mantle: molten rock, solid, dense
Flows like toothpaste
Thickest part (70% of earth’s volume), mostly solid except for upper mantle being able to flow like “thick toothpaste”

5. Made up of liquid iron and nickel Inner Core 1200 km thick
Outer Core
2200 km thick
Made up of liquid iron and nickel
Inner Core
1200 km thick
solid iron and nickel (due to tremendous pressure)
Extremely hot 5,500°C
5000C is about 4x the melting pt of iron. Pressure keeps it solid. Inner and outer cores believed to rotate at different speeds and may be responsible for Earth’s magnetic fields.

6. Tectonic Plate Layers LITHOSPHERE:
Outer layer of rock composed of crust and part of upper mantle.
Makes up the
tectonic plates
km thick
Like a hard boiled egg with moving broken shell pieces, Earth’s outer layer is composed of several large rigid but mobile chunks of rock (Tectonic Plates). Made up of crust and uppermost mantel = lithosphere km thick. 12 major plates and many smaller ones.
Heat that keeps asthenosphere molten comes from radioactive elements

7. ASTHENOSPHERE:
Makes up molten layer beneath plates
Lower Mantle
So hot it behaves like plastic, less rigid, flows like toothpaste

8. Tectonic Plates 12 major plates and many smaller ones.
Oceanic Plates – contain dense basalt
Continental Plates – granite
Interactions between lithosphere and asthenosphere help explain plate tectonics because the hotter, plastic mantle material (asthenosphere) beneath can flow enabling plates (lithosphere) to move.
Two types of Plates

9. Questions
Tectonic plates are composed of which parts of Earth’s layer?
What are two types of crust?
Describe two features of each.

10. V. Plate Interactions : Boundaries
Plate boundaries are marked by earthquakes, volcanoes, mountain ranges and ocean trenches
There are three main types of plate boundaries:
Divergent
Convergent
Transform

11. Melting crust rises beneath the subduction zone, forming volcanoes parallel to the plate boundary;
trenches are found beneath the ocean where the oceanic crust subducts;

12. 1) Divergent Boundaries (spreading center)
When two plates separate and create new oceanic crust.
Sea floor spreads along a mid-ocean ridge.
Can also occur in middle of continents (continental rifting)
Mid-Atlantic ridge –
largest mountain range
Huge mountain ranges found beneath the Earth’s oceans known as mid-ocean ridges due to sea floor spreading
Mid-Atlantic ridge is a system of spreading ridges . About 16000km largest mountain range on Earth, with greatest amount of volcanic activity.
Basaltic lava pours out from the ridges and spreads out to form new oceanic crust

13. Divergent Boundaries Mid-Atlantic ridge
Mid-Atlantic -largest mountain range

14. Divergent Boundaries
Endeavour hydrothermal vents were created as the Juan de Fuca plate moves away from the Pacific plate

15. Diverging Plates
Diverging plates at the East African Rift are slowly breaking Africa into pieces

16. Convergent Boundaries
Where two plates collide
Denser crust eventually goes below the less-dense crust (subduction), causing deep sea trenches to form
Volcanoes and Mountains form, earthquakes common
variable results depending on the plates involved

17. a) Continental-Oceanic Plates
When dense oceanic plates collide with continental plates, the oceanic plate will sink under the continental plate and be pushed into the mantle (subducted).
Continental crust is less dense than oceanic crust and never subducts
Trench forms
Sometimes volcanoes

18. Cone-shaped volcanoes of West Coast of North America are result of oceanic –continental convergence between Juan de Fuca Plate (oceanic) and North American Plate (continental).

19. Cascade Mountain Range
Mount Garibaldi – result of the Juan de Fuca plate subducting under the North American plate
Mount Meager
Although plates move slowly, great forces are involved. Colliding plates may resist the force of convection currents, ridge push and slab pull. Pressure builds as long as the plate remain stuck in place. When te stress is too great, energy released in earthquake.

20. c) Oceanic-Oceanic Plates
When two oceanic plates collide, usually one plate subducts beneath the other.
Volcanic Island Arcs form above the non-subducting plate.
chain of volcanic islands=volcanic island arc
subduction zone is the biggest crash scene on Earth. These boundaries mark the collision between two of the planet's tectonic plates. The plates are pieces of crust that slowly move across the planet's surface over millions of years.
here two tectonic plates meet at a subduction zone, one bends and slides underneath the other, curving down into the mantle. (The mantle is the hotter layer under the crust.) 
Tectonic plates can transport both continental crust and oceanic crust, or they may be made of only one kind of crust. Oceanic crust is denser than continental crust. At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust. (Sometimes, oceanic crust may grow so old and that dense that it collapses and spontaneously forms a subduction zone, scientists think.) 

21. Islands of Japan
and Indonesia
and the Aleutian
Island of Alaska

22. Pacific Ring of Fire

23. Pacific Ring of Fire
The Ring of Fire is a major area in the basin of the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur.
Geologic features along the Ring of Fire include not only volcanoes, but ocean trenches, mountain trenches, hydrothermal vents, and sites of earthquake activity.
(c) McGraw Hill Ryerson 2007

24. The Ring of Fire is a string of volcanoes and sites of seismic activity, or earthquakes, around the edges of the Pacific Ocean. Roughly 90% of all earthquakes occur along the Ring of Fire, and the ring is dotted with 75% of all active volcanoes on Earth. 
The island nation of Japan lies along the western edge of the Ring of Fire, and is one of the most tectonically active places on Earth. As much as 10% of the world’s volcanic activity takes place in Japan.

25. c) Continental-Continental Plate Convergence
When continental plates collide, neither plate is dense enough to be pushed down, so the land buckles like a car hood in a car crash (“uplifting”), forming mountain ranges;
Subduction does not occur due to similar densities.
If the same kind of crust collides, such as continent-continent, the plates may crash together without subducting and crumple together like crashing cars. The massive Himalaya mountain chain was created this way, when India slammed into Asia.

26. Himalayan Mountain Range
Himalayas formed from Indian continent colliding with Asian continent.
Continue to increase in elevation by several cm per year
Youngest and highest mountain range.
40-50million years ago.
Increasing due to steady norothward movement of indian plate

27. 3) Transform Boundaries
Where two plates slide by each other
Results in frequent earthquakes and faults
Fault – breaks in rock layers due to movement on either side
Mostly occur near ocean ridges
No mountains or volcanoes form.

28. 3) Transform Boundaries
First identified by Canadian geologist, John Tuzo Wilson.
Earthquakes are common at these boundaries
Oct 2012, an earthquake of magnitude of 7.7 originated from movement along the Queen Charlotte Fault.

29. Transform Boundary
San Andreas Fault

30. Plate Boundary Symbols

31. III. Plate Motion
Tectonic plates make up the lithosphere (crust and upper portion of mantle), which floats on the asthenosphere (molten, lower mantle).
Tectonic plates are all moving at the same time
extra

32. III. Plate Movement Variable temperature causes convection currents
Convection demo
See pages
(c) McGraw Hill Ryerson 2007

33. Mantle Convection
Molten rock called magma in the mantle is heated up near the core of the earth and becomes less dense and buoyant.
Warmer, less dense material rises and cooler, denser material sinks, causing convection current.
As magma moves,
it drags the tectonic
plates above with it.
Continents, attached to the tectonic plates, float in the magma of the asthenosphere.As magma is heated in the asthenosphere, convection currents form.Rising magma can reach the surface at ridges (in the oceans) or rifts (on land).The magma cools when it reaches the surface, solidifies, and is pushed aside as new magma pushes from below. This is called ridge push.
Tectonic plates are all moving at the same time.
There are 12 large tectonic plates and many smaller ones.
Where continental and oceanic plates meet, subduction occurs.
The denser oceanic plate subducts under the lighter continental plate.
By “slab pull,” the rest of the plate follows.
Large earthquakes and volcanoes are found in
subduction zones.
Heat from the core causes convection currents in the mantle. These currents slowly move the crust around. In some places the crust is destroyed. In other places new crust is formed

34. Rising magma pushes plates apart at spreading centers in oceans
Colder, dense magma near the surface sinks.
The rotation causes movement of the plates.
Rising magma can reach the surface at ridges (in the oceans) or rifts (on land).The magma cools when it reaches the surface, solidifies, and is pushed aside as new magma pushes from below. This is called ridge push.

35. The Earth’s Temperature
As you go deeper into the Earth’s crust, the temperature increases about 1oC for every 40 m of depth 
Beneath the crust, this temperature rise gradually slows, until a core temperature of about 7000oC is reached.

36. The Earth’s heat comes from:
radioactive element decay (uranium, potassium, thorium);
friction between rock masses in the crust and mantle;
heat left over from planetary formation.

37. Two other processes affecting plate movement
Ridge Push – rising material spread out as it reaches the upper mantle. This cause the lithosphere to lift and push tectonic plates apart at divergent plate boundaries.

38. Slab Pull
Slab Pull – as the leading edge of a subducting plate sinks, it pulls the rest of the plate with it at convergent plate boundaries.
Gravity and convection assist this movement.

39. Name and draw three main types of tectonic plate boundaries.
Why does subduction not occur at some kinds of tectonic plate boundaries?
Describe the process that results in a volcanic island arc.
Name a mountain range produced by continental-continental plate convergence.