1. INTRODUCTION TO PLATE TECTONICS

2. THE EARTH LAYERS AND PLATE TECTONICS
Plate tectonics is the theory that Earth's outer layer is made up of plates, which have moved throughout Earth's history.
This theory also explain how and why volcanoes, earthquakes and mountains are formed.
Exactly what drives plate tectonics is not known. One theory is that convection within the Earth's mantle pushes the plates.
The story of plate tectonics really starts deep within the Earth, so lets take a look inside first. Although the Earth appears to be made up of solid rock it’s actually made up of three distinct layers: the crust, mantle, and core. Each layer has its own unique properties and chemical composition.

3. LAYERS OF THE EARTH

4. LAYERS OF THE EARTH
Ocean - large bodies of water sitting atop oceanic crust.
Crust - the rigid, rocky outer surface of the Earth, composed mostly of basalt and granite. The crust is thinner under the oceans.
Oceanic Crust - thin parts of the Earth's crust located under the oceans.
Oceanic Ridge - newly-formed region of the oceanic crust.
Lithosphere - the crust plus the rigid, upper mantle.
Upper Mantle (rigid) - the uppermost part of the mantle, part of the lithosphere.
Asthenosphere = Upper Mantle (flowing) - the lower part of the upper mantle that exhibits plastic (flowing) properties. It is located below the lithosphere (the crust and upper mantle).
Lower Mantle (semi-rigid) - the deepest parts of the mantle, just above the core.
Magma - molten rock within the Earth's mantle. In seafloor spreading, magma moves from the asthenosphere to the crust.
Inner core - the solid iron-nickel center of the Earth that is very hot and under great pressure.
Outer core - the molten iron-nickel layer that surrounds the inner core.

5. LAYERS OF THE EARTH

6. THE LAYERS OF THE EARTH

7. THE LAYERS OF THE EARTH
Crust - The Earth's outermost surface is called the crust. The crust is typically about 25 miles thick beneath continents, and about 6.5 miles thick beneath oceans.
The crust is relatively light and brittle. Most earthquakes occur within the crust.
The crust in this image is much smaller in the real earth!  

8. THE EARTH LAYERS
Mantle - The region just below the crust and extending all the way down to the Earth's core is called the mantle. The mantle is relatively flexible so it flows instead of fracturing

9. THE LAYERS OF THE EARTH
Core - Beneath the mantle is the Earth's core. The Earth's core consists of a fluid outer core and a solid inner core. Because the outer core contains iron, when it flows it generates a magnetic field. This is the source of the Earth's magnetic field .

10. PLATE TECTONICS
All the possible movements of the earth’s plates, including drift toward or away from other plates and the process that deforms or changes the earth’s surface are included in the diastrophism.
Diastrophism is the process of deformation that changes the earth’s surface. It produces many of the basic structures you see in the earth’s surface such as plateaus, mountains and folds in the crust .
Vulcanism or volcanism is the movement of magma.
Diastrophism, volcanism and earthquakes are closely related and their occurrence can be usually explained by events involving plate tectonics.

11. PLATE TECTONICS
The earth’s rigid crust or lithosphere is not a continuous shell but is broken up into a mosaic of about 12 larger plates and a number of smaller ones.
These plates are in motion over the earth’s surface and their motion result from convection currents within the asthenosphere below.
The largest is the Pacific Plate and it comprises most of the Pacific Ocean Basin
Some of the plates have been named after the continents they contain
No plate however is identical to the shape of any continent.
The North American plate for example extends from the pacific coast of North America to the middle of the Atlantic Ocean where it meets the Eurasian and African Plates.
There are also a number of smaller plates e.g. the Juan Fuca Plate , a piece of oceanic lithosphere trapped between the giant Pacific and North American plates just offshore of North Western United States

12. THE EARTH PLATES
The outer surface of the earth is made of 12 major plates and several smaller plates. 
The plates are all moving in different directions and at different speeds (from 2 cm to 10  cm per year--about the speed at which your fingernails grow) in relationship to each other.
The plates are moving around like cars in a demolition derby, which means they sometimes crash together, pull apart, or sideswipe each other.
The place where the two plates meet is called a plate boundary. Boundaries have different names depending on how the two plates are moving in relationship to each other.
These plates move towards each other (convergent boundaries), away from each other (spreading or divergent boundaries), or slide past each other (transform boundaries

13. THE EARTH MAJOR PLATES

14. THE EARTH MAJOR PLATES

15. PLATE BOUNDARIES
Many geological features develop through the interactions of plates at their boundaries.
There are three basic types of Plate Boundaries
Constructive/Divergent
Destructive /Convergent
Conservative/Transform
These three types or boundaries form an idealized model of plate tectonics however these types also occur in various combinations. There are also oblique boundaries that combine divergence and convergence also stike -slip and others.

17. Constructive/Divergent Boundaries
Divergence is typically characterized by rifting. It arises when two plates move apart and new crust is created.
They are mainly found between oceanic plate and usually occur underwater.
Oceanic plate separation
On the seafloor the boundary between separating plates is marked by a mid ocean ridge where active volcanism earthquakes and rifting are exhibited.
A major example of this is the Mid Atlantic Ridge. Here sea floor spreading operates as the North American and Eurasian Plates separate and new seafloor is created at these spreading centres. The MAR surfaces above sea level in Iceland.

18. RIFTING AND SPREADING ALONG THIS DIVERGENT PLATE BOUNDARY HAS CREATED A MID -OCEANIC MOUNTAIN CHAIN WHERE VOLANOES AND EARTHQUAKES ARE ACTIVE

19. Continental Plate Separation ( RARELY OCCURS )
Where continental plates separate such as the early stages of the Great Rift Valley of East Africa.
They are also characterized by volcanic activity, earthquakes and rift valleys.
The Red Sea and the Gulf of California are rifts. The continents have separated enough for new seafloor to form along the axis and the rift valleys have been flooded by the ocean.
The island of Madagascar may have separated from Africa as a result of rifting forming new ocean basin between

20. Destructive/Convergent Boundaries
Is plates separate in one place then they must converge somewhere else.
When two plates collide with each other one is forced to subduct or neither subducts.
The features present will depend on what type of plates are converging.
The Pacific Ocean is surrounded by destructive plate margins and their associated features. Its perimeter is known as the Ring of Fire.

21. Ocean-Ocean Convergence
When two oceanic plates converge one descends beneath the other in a process called subduction.
The oceanic lithosphere of the subducting plates sinks into the asthenosphere and is eventually recycled.
This downward movement if the plate creates a narrow deep sea trench e.g.. The Marianas Trench in the West Pacific where the ocean reaches its deepest depths of about 10km deeper than the height of Mt Everest.
As the plate descends pressure increases and the water trapped in the rocks of the plate is squeezed out and rises into the astenosphere causing the mantle to melt producing a chain of volcanoes called a volcanic island arc.

22. Ocean-Ocean Convergence

23. Ocean-Continent Convergence
When an oceanic plates converges with a continental plate the oceanic plate subducts and the continental plates overrides it. This occurs because continental crust is much lighter ..
The continental edge crumples and is uplifted into a mountain chain that runs roughly parallel to the deep sea trench.
Sediment collecting in the trench may also be scraped upwards to form mountains
The forces of collision and subduction creates earthquakes along a subduction zone( Benioff Zone).
Along the west coast of South America the South American Plate collides with the Nazca Plate ,a great chain of mountains is formed called the Andes Mountains on the continental side and the Peru-Chile Trench lies off the coast.

24. Ocean-Continent Convergence

25. OCEANIC –CONTINENTAL COLLISION

26. Continent-Continent Convergence
When a continental plates converges with a continental plate subduction does not occur. Instead both are crumpled onto each other forming deep rooted fold mountains.
This zone between the boundary is known as the suture line.
These boundaries marks sites at which the earths crust is thickest.
This occurs where the Indian and Eurasian plates both with continents on their leading edges collide. The Eurasian plate overrides the Indian Plate but India and Asia remain afloat creating a double thickness of crust forming the highest mountain range in the world the Himalayas.
The forces of crumpling creates earthquakes.

27. Continent-Continent Convergence

28. Transform /Passive Boundaries
At these boundaries plates slide past each other. Lithosphere is neither created nor destroyed.
These boundaries are transform faults, fractures along which relative displacement occurs as horizontal slip between the adjacent blocks.
These boundaries are typically found along mid ocean ridges where the divergent boundary is broken and offset in a step like manner.
San Andreas fault in California is an excellent example. Here the Pacific plate slides past the North American Plate.
Sudden slip along these faults produce large earthquakes like the one that destroyed San Francisco in 1906.

29. Transform /Passive Boundaries

30. THE PRESENT-DAY CARIBBEAN PLATE IS DEFINED BY EARTHQUAKES AND VOLCANIC ACTIVITY Earthquake epicentres: black dots and circles. Volcanic centres: red triangles, open-active

31. CARIBBEAN PLATE SETTING