2018 Year 9 Plate Tectonics

Question 1

Explain the theory of continental drift.

Answer 1

Continental drift is the separation of the continents by drifting along the oceans. Alfred Wegener proposed this theory after noticing that Africa and South America could fit together like a jigsaw puzzle

Question 2

Explain the theory of seafloor spreading.

Answer 2

Seafloor spreading is the process of new crusts forming at the ocean ridges and spreading outwards. This theory was proposed by Harry Hess.

Question 3

Which layer of the Earth is comprised mainly of molten iron and nickel?

Answer 3

The Earth’s core

Question 4

What is an oceanic ridge?

Answer 4

An oceanic ridge is an underwater mountain

Question 5

Know the 3 types of plate movements and what each one is called

Answer 5

Divergent plates, convergent plates and transformer tectonic plates. Divergent plates divide, convergent plates collide and transformer tectonic plates slide

Question 6

What evidence supports the Tectonic plate theory?

Answer 6

South America and Africa fit together like a puzzle piece. Also there are fossils of some ancient species that have been discovered in different continents.

Question 7

Why is Australia geologically stable?

Answer 7

Australia is geologically stable because the lithosphere under Australia is about twice as deep as all the other continents. This makes Australia resistant to melting and fracture. Also, Australia isn’t near any plate boundaries and therefore hasn’t had many earthquakes.

Question 8

How does the theory of plate tectonics explain volcanoes?

Answer 8

Two transformer tectonic plates will slowly slide past each other but suddenly quickly slip past each other. This causes Earthquakes. When oceanic an continental plates collide, the oceanic plate sinks under the continental plate because it is denser. The continental plate then becomes distorted, forming volcanoes.

Question 9

Explain constructive and destructive boundaries

Answer 9

Magma rises into rifts created by diverging boundaries and solidifies, creating new crust. This is why divergent plates are known as constructive boundaries. Converging boundaries collide with each other, destroying rock. This is why convergent plates are known as destructive boundaries.

Question 10

What’s the difference between the epicentre of an Earthquake and the focus of an Earthquake?

Answer 10

The exact spot where the Earthquake begins is an Earthquake’s focus. The point on the surface directly above where the Earthquake begins is the Earthquake’s epicentre