Plate tectonics

What are the layers of the earth?

1. Crust

2. Mantle

3. Outer core

4. Inner core

What is the crust?

The outermost layer of the earth

What are the two types of crust?

Oceanic and continental

Continental crust

A Portion of the earths crust

What rock is continental crust mostly made from?

Lighter rocks, mostly granite

Whats are the 2 minerals in the continental crust?

Silica and Alumina

How thick is the continental crust?

25-70km

How much of the earth is covered in continental crust?

40%

What is oceanic crust?

The earths crust located under the ocean

What rock is oceanic crust mostly made from?

Heavier rocks, mostly basalt

Whats are the 2 minerals in the continental crust?

Silica and Magnesium

How thick is oceanic crust?

3-10km

What is the moho line?

The boundary between the crust and rigid upper mantle in the lithosphere

What is the lithosphere?

The crust and upper mantle

What are the separate layers of the mantle called?

1. The rigid upper mantle

2. The semi-molten upper mantle

3. The lower mantle

Describe the solid upper mantle.

Connected to the outer crust

50-200km Thick

What is the asthenosphere?

The semi molten upper mantle.

How thick is the asthenosphere?

About 100km

Describe the lower mantle.

Hottest and largest section

Made of entirely molten mantle

Contains the convection currents that move plates

Describe the outer core.

Hot liquid rock

Temperatures up to 4,000

High % of iron small % of nickel

Describe the outer core.

Solid nickel and iron

Temperatures up to 5,000 - 6,000

Who proposed that all the continents fit together ?

Alfred Wegener

What was the past supercontinent called?

Pangaea

What is the first theory of continental drift?

Continental fit
- East Coast of South America and the west Cost of the African Plate fit together like a Jigsaw Puzzle

What is the second theory of continental drift?

Fossil Similarity
- Ancient fresh water Mesosaurus discovered in Africa and South America
- Couldn't have swam across the Atlantic Ocean, theory suggests they one shared a habitat of rivers and lakes.

What is the thrid theory of continental drift?

Ice sheets once covered placed that are now warm
- India, Australia and South Africa could support an Ice Age but remains were once found there
- Suggest these areas once existed at different latitudes

Who Discovered Sea Floor Spreading?

Harry Hess

What are endogenic forces?

Forces within the earths crust that cause the surface to move horizontally and vertically

How did Harry Hess discover sea floor spreading?

The age of the rock gets progressively older the further away from the mid-ocean ridge you get

Rocks get progressively older and deeper the further away from the magma point

Describe the process of convection currents.

- Magma is heated by energy from the earth’s core.
-This causes the magma to expand and rise to the side away from the source.
- This side-way movement brings the lithosphere with it.
- Magma sinks and repeats again

What is the Pacific Ring of Fire?

A Ring in the Pacific where many plates are converging leading to many volcanoes and earthquakes occurring there

What is a subduction zone?

Where one of the crust plants sinks downwards into the mantle beneath another place

What is a ocean trench?

A deep, underwater trough created by one plate subducting under another plate

Give an example of a Divergent Boundary.

Eurasian and North American

Give an example of a Convergent Boundary.

Eurasian and Pacific

Give an example of a Transform Boundary.

North American and Pacific

What happens when 2 Oceanic plates Collide?

1. Convection currents in the mantle drag the denser plate downwards

2. An arc-shaped ocean trench is formed at the subduction zone

3. Fluids and gasses are released from the crust as it sinks towards the mantle

4. Silica and gas-rich magma is formed from the destroyed crust

5. As it rises the new magma burns a path through the lighter crust

6. This magma reaches the surface of the earth and forms a chain of volcanic islands called an island arc paralell to

What happens when 2 continental plated Collide?

- Very little subsection because rocks are similar in age weight and density
- Two plated buckle upwards slowly, creating bold mountain ranges E.g Alps - Magma intrudes though gaps curated between layers of rock
- Magma cools slowly creating new rock under the surface if the earth

What happens when a continental and oceanic plate collide?

- same as oceanic oceanic - continental plate buckles upwards

What is the Mid-Atlantic Ridge?

The North American and Eurasian are constructive plate boundaries. They create fissures and cracks between each other. Magma rises where it cools and forms