PLATE TECTONICS

Why the Earth is Like It Is

What Did The Earth Look Like In The Past?

Why Do Plates Move?Plates are “pushed” and “pulled” over the surface of the Earth due to unbalanced forces.

REMEMBER CONVECTION? Convection currents reach the surface, plates are pushed apart.As the plates move away from each other, part of them are pulled into the Earth’s mantle.

Names of Plates

Plate Move In Different Ways

Plates Move Away From Each OtherThis is called Divergence – these are constructive boundaries since they produce new land as magma rises to the surface to fill in the space.

Click to view animation – minimize PPT screen to see webpage

Rift Valley forms if the land is above water

Sea Floor Spreading forms ridges as the sea floor spreads apart and lava rises

Resulting landforms from Divergence – Moving Apart

Click to view interactive

map

Plates Move Toward Each OtherThis is called Convergence – these are destructive boundaries since they deform the plates. Collision or Subduction occurs as the more dense plate slide under the less dense plate.

Continent/Continent

Ocean/Continent

Ocean/OceanClick to view animation minimize PPT screen to see webpage

Resulting landforms from Convergence – Moving Together

TrenchesMountains

Structural Mountains

VolcanoesClick to view interactive map

Plates slide paste each other When plates are sliding past each other in opposite directions it is a Transform Boundary.

• Transform boundaries occur in a few places to accommodate lateral, or side to side motion, in which plates slide past one another.

Click to view animation minimize PPT screen to see webpage

When two plates are sliding past each other in opposite directions it creates a fault line. The result of two huge plates of land moving opposite one another is that massive amounts of energy build up. Occasionally this energy is released suddenly in the form of an earthquake.

Resulting landforms from Transform Boundaries – sliding past each other

Click to view interactive map

TAKS Type Items and Answer Analysis

As two continental plates move toward each other, what landforms would you expect to see?

A. VolcanoesB. CliffsC. MesasD. Structural Mountains

As two continental plates move toward each other, what landforms would you expect to see?

A. Volcanoes Incorrect

These form at edges of plates or over hot spots.

As two continental plates move toward each other, what landforms would you expect to see?

B. Cliffs Incorrect

These are erosional landforms or minor uplift areas.

As two continental plates move toward each other, what landforms would you expect to see?

C. Mesas Incorrect

These are erosional landforms in a desert.

As two continental plates move toward each other, what landforms would you expect to see?

D. Structural Mountains – correct - Two continental masses will push into each other and “crumple” the edges to form mountains.

Where would you find the newest land on Earth?A. In areas of continental convergenceB. In areas where two ocean plates come

togetherC. In areas where plates are moving apartD. In areas where two plates are sliding past each

other

Where would you find the newest land on Earth?A. In areas of continental convergenceIncorrect

Structural mountains would form here from existing land.

Where would you find the newest land on Earth?B. In areas where two ocean plates come

togetherIncorrect

You would find trenches and subduction in this area.

Where would you find the newest land on Earth?D. In areas where two plates are sliding past each

otherIncorrect

You would find land movement, but not new land being formed.

Where would you find the newest land on Earth?C. In areas where plates are moving apartCorrect

When plates move apart, it is due to magma reaching the surface. When magma cools, new land is formed.