year 9 unit The Earths plate movement.pptx

dynamic earth unit for year 9

1. The Earths plate movement Plates move upon the asthenosphere- layer of partially molten rock. They move because nuclear reactions in the core produce heat. The heat causes the mantle material to expand and rise towards the surface. When it reaches the surface, it cools and moves downward due to gravity. This cycle of the convection currents and the effect of the gravitational forces cause the plates to move.

2. Plate boundaries Divergent boundaries divergent boundaries are caused when two plates move apart. This normally happens in the middle of the ocean floor.

3. Mid oceanic ridge (MOR) a MOR is a divergent boundary where new material comes through the crust and forms new rock on the ocean floor. Because lava can escape through the crack between the two plates a MOR is seen as a type of volcano, however it is not explosive.

4. Convergent boundaries Convergent boundaries are caused when two plates collide. There are three different types of collisions that can occur. Ocean crust hits ocean crust Ocean crust hits continental crust Continental crust hits continental crust What do you think could be made from two plates colliding?

5. Types of convergent boundaries Continental crust hits continental crust Ocean crust hits continental crust Ocean crust hits ocean crust

6. Volcanic and non volcanic mountains Volcanoes occur when ocean hits continent or ocean hits ocean crust. Non- volcanic mountains can occur when continent hits continent. Volcanoes produced by plates colliding are very explosive and can cause a lot of damage. Earthquakes can also occur in these regions from the friction of colliding plates. Non volcanic mountains Volcanic mountains

7. Transform boundaries Transform boundaries are caused when two plates slide along each other. The edges of plates are rough and as they rub they cause a lot of friction.

8. Earthquakes An earthquake is a sudden release of energy in the form of vibrations and tremors from the earth’s surface. Caused by compressed or stretched rock snapping along a fault in earth’s surface. Most earthquakes are minor and pass unnoticed.