1. The difference between asthenosphere and lithosphere is how the materials in these layers can flow. Rocks in the lithosphere are "rigid", meaning that they can bend but they cannot flow. Rocks in the asthenosphere are "plastic", meaning that they can flow in response to deformation.
The lithosphere is broken up into rigid plates that ride on top of the flowing asthenosphere.
In terms of chemical composition, there is no difference between the upper part of the asthenosphere and the lower part of the lithosphere. In fact, if the upper part of the asthenosphere cools down it becomes part of the lithosphere.

2. Movement of plates is caused by thermal convection of the “plastic” rocks of the asthenosphere which drag along the overlying lithospheric plates.
3-3
Driving Mechanisms for Plate Motions

3. Convection Cells

4. Plate boundaries

5. Earth’s surface is composed of a series of lithospheric plates
Earth’s surface is composed of a series of lithospheric plates. Plate edges extend through the lithosphere and are defined by seismicity.
Plate edges are trenches, oceanic ridges and transform faults.
Seismicity and volcanism are concentrated along plate boundaries.

6. There are four types of plate boundaries
CONSTRUCTIVE /Divergent boundaries -- where new crust is generated as the plates pull away from each other.
DESTRUCTIVE /Convergent boundaries -- where crust is destroyed as one plate dives under another.
CONSERVATIVE /Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.
Plate boundary zones -- broad belts in which boundaries are not well defined and the effects of plate interaction are unclear.

7.                                                                                                                     
Artist's cross section illustrating the main types of plate boundaries (see text); East African Rift Zone is a good example of a continental rift zone. (Cross section by José F. Vigil from This Dynamic Planet -- a wall map produced jointly by the U.S. Geological Survey, the Smithsonian Institution, and the U.S. Naval Research Laboratory.)

9. Ridge Push The molten magma that rises at a mid-ocean ridge is very hot and heats the rocks around it. As the asthenosphere and lithosphere at the ridge are heated, they expand and become elevated above the surrounding sea floor.
This elevation produces a slope down and away from the ridge.
Because the rock that forms from the magma is very hot at first, it is less dense and more buoyant than the rocks farther away from the mid-ocean ridge.
However, as the newly formed rock ages and cools, it becomes more dense. Gravity then causes this older, denser lithosphere to slide away from the ridge, down the sloping asthenosphere.
As the older, denser lithosphere slides away, new molten magma wells up at the mid-ocean ridge, eventually becoming new lithosphere.
This force is called ridge push, though the phrase “ridge push” is somewhat misleading. It might be more accurate to refer to ridge push as gravitational sliding.

10. Slab Pull
At a subduction boundary, one plate is denser and heavier than the other plate.
The denser, heavier plate begins to subduct beneath the plate that is less dense.
The edge of the subducting plate is much colder and heavier than the mantle, so it continues to sink, pulling the rest of the plate along with it.
The force that the sinking edge of the plate exerts on the rest of the plate is called slab pull.
Currently, many scientists consider slab pull to be a much stronger factor than ridge push or mantle convection in driving plate movements.
Slab pull can be compared to the following situation: Suppose your jacket is resting on a table. You drop a heavy set of keys into a pocket that is dangling over the edge. The weight of the keys pulls downward on the rest of the jacket, causing it to slide toward the edge of the table

11. Convection Currents
Hot magma in the Earth moves toward the surface, cools, then sinks again.
Creates convection currents beneath the plates that cause the plates to move.

14. CONSTRUCTIVE/Divergent Boundaries
Boundary between two plates that are moving apart or rifting
 
RIFTING causes SEAFLOOR SPREADING

15. Features of Constructive/Divergent Boundaries
Mid-ocean ridges
rift valleys
fissure volcanoes

16. Constructive

18. Mid-Ocean Ridge

20. Lava fountains (10 m high) spouting from eruptive fissures during the October 1980 eruption of Krafla Volcano. (Photograph by Gudmundur E. Sigvaldason, Nordic Volcanological Institute, Reykjavik, Iceland.)

21. Aerial view of the area around Thingvellir, Iceland, showing a fissure zone (in shadow) that is the on-land exposure of the Mid-Atlantic Ridge. Right of the fissure, the North American Plate is pulling westward away from the Eurasian Plate (left of the fissure). Large building (near top) marks the site of Lögberg, Iceland's first parliament, founded in the year A.D (Photograph by Oddur Sigurdsson, National Energy Authority, Iceland.)

22. In East Africa, spreading processes have already torn Saudi Arabia away from the rest of the African continent, forming the Red Sea. The actively splitting African Plate and the Arabian Plate meet in what geologists call a triple junction, where the Red Sea meets the Gulf of Aden. A new spreading center may be developing under Africa along the East African Rift Zone.

23. Constructive

24. DESTRUCTIVE/Convergent Boundaries
Boundaries between two plates that are colliding
 
There are 3 types…

25. Type 1
Ocean plate colliding with a less dense continental plate
Subduction Zone: where the less dense plate slides under the more dense plate
VOLCANOES occur at subduction zones

27. Andes Mountains, South America

28. Earth’s surface is composed of a series of lithospheric plates
Earth’s surface is composed of a series of lithospheric plates. Plate edges extend through the lithosphere and are defined by seismicity.
Plate edges are trenches, oceanic ridges and transform faults.
Seismicity and volcanism are concentrated along plate boundaries.

29. Ring of Fire
Challenger Deep got its name from the British survey ship Challenger II, which pinpointed the deep water off the Marianas Islands in 1951.

30. Type 2 Ocean plate colliding with another ocean plate
The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH

32. Type 3 A continental plate colliding with another continental plate
Have Collision Zones:
a place where folded and thrust faulted mountains form.

36. Earth’s surface is composed of a series of lithospheric plates
Earth’s surface is composed of a series of lithospheric plates. Plate edges extend through the lithosphere and are defined by seismicity.
Plate edges are trenches, oceanic ridges and transform faults.
Seismicity and volcanism are concentrated along plate boundaries.

38. CONSERVATIVE/ Converse Fault Boundaries
Boundary between two plates that are sliding past each other
EARTHQUAKES along faults

39. 3-4
Conservative
The San Andreas fault in southern California is a transform fault that connects the sea-floor spreading ridge of the Gulf of California with the spreading ridge off Oregon and Washington.
If these plate motions continue, Baja will splinter off California.

40. Conservative
Because the San Andreas fault has an irregular trace, strike-slip motion can cause local compression or tension.
3-4

42. Hot Spots

43. Mantle plumes originate deep within the asthenosphere as molten rock which rises and melts through the lithospheric plate forming a large volcanic mass at a “hot spot”.
Mantle Plume

44. Plate-boundary zones
Not all plate boundaries are as simple as the main types discussed above. In some regions, the boundaries are not well defined because the plate-movement deformation occurring there extends over a broad belt (called a plate-boundary zone). One of these zones marks the Mediterranean-Alpine region between the Eurasian and African Plates, within which several smaller fragments of plates (microplates) have been recognized. Because plate-boundary zones involve at least two large plates and one or more microplates caught up between them, they tend to have complicated geological structures and earthquake patterns.