Top Banner
25
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Plate tectonics
Page 2: Plate tectonics

The theory that states that piecesof Earth’s lithosphere are inconstant, slow motion, driven byconvection currents in the mantle.

Page 3: Plate tectonics

• The theory of plate tectonicsexplains the formation,movement, and subduction ofEarth’s plates.

Page 4: Plate tectonics

Forces that causes Earth’splates to move.

• The plates of the lithosphere float on top of the Asthenosphere.

• Convection currents rise in the Asthenosphere and spread outbeneath the lithosphere.

• Convection current forces drag the overlying plates along. Thecurrents cools and sinks deeper into the mantle.

• Scientist think that the downward movement may provide theforce that causes the subduction of plates carrying oceanic crust.

Page 5: Plate tectonics

Forces that causes Earth’splates to move.

Page 6: Plate tectonics

Slab Push Hypothesis

• Magma rising along the mid oceanicridge exerts a force that pushes an oceanicplate away from the ridge.

• The force of gravity causes platemovement by pulling cooler, denseroceanic plates down toward the mantle.

• Slab push and pull work together withconvection currents to move the plates.

Page 7: Plate tectonics

The earth’s surface is madeup of about nine large plates& several smaller plates.

Page 8: Plate tectonics
Page 9: Plate tectonics

Places where two plates meet.

Page 10: Plate tectonics
Page 11: Plate tectonics

There are three types ofplate boundaries.

1. Transform Boundary

2. Divergent Boundary

3. Convergent Boundary

Page 12: Plate tectonics

Two plates slip past eachother, moving in oppositedirections.

Page 13: Plate tectonics

Earthquakes occur frequentlyalong this boundary.

Page 14: Plate tectonics

The SanAndreasfault inCalifornia isan exampleof atransformboundary.

Page 15: Plate tectonics

Two plates move away fromeach other.

Page 16: Plate tectonics

• When divergent boundarydevelop on land, two of Earth’splates slide apart.

• A rift valley forms along thedivergent valley.

• Ex. The Great Rift Valley ineast Africa is about 3,000kilometers long.

Page 17: Plate tectonics
Page 18: Plate tectonics

Two plates move towardseach other.

Page 19: Plate tectonics

• When plates converge, itresults in a collision.

• Collisions happen between:

1. Oceanic crust to oceanic crust

2. Oceanic crust to continental crust

3. Continental crust to continental crust

Page 20: Plate tectonics
Page 21: Plate tectonics
Page 22: Plate tectonics
Page 23: Plate tectonics

Plate Movement

• The plates move at about 1-10centimeters per year.

• The North American and Eurasianplates move at about 2.5 cm/year.

Page 24: Plate tectonics

Plate Movement

• Pangaea existed about 260 millionyears ago.

• Approximately 225 million years agoPangaea began to break apart.

Page 25: Plate tectonics

Plate Movement