Plate Tectonic Theory

Question 1

What is the thickness and temperature of the crust?

Answer 1

Thinnest layer (5-70km) and is the coldest layer

Question 2

What is the crust made up of?

Answer 2

Solid rock that is broken up into pieces called tectonic plates and it contains rocks and minerals

Question 3

How does the composition of the crust change?

Answer 3

Under the oceans it’s basalt but under the continents it’s granite

Question 4

What is the thickness and temperature of the mantle?

Answer 4

It is the thickest layer and varies from 1000°C near the crust and 3700°C near the outer core

Question 5

What is the mantle made up of?

Answer 5

Semi-molten - solid rock that can flow

Question 6

How does the mantle move?

Answer 6

In slow, big circles caused by convection currents

Question 7

What is the thickness and temperature of the outer core?

Answer 7

About 2300km thick and usually between 3700°C - 5000°C

Question 8

What is the outer core made up of?

Answer 8

Semi-liquid iron

Question 9

How does the iron in the outer core affect the earth?

Answer 9

The semi-liquid iron is magnetic which means the earth’s magnetic field is formed here which protects us from harmful solar winds and allows life on our planet

Question 10

What is the thickness and temperature of the inner core?

Answer 10

About 1250km thick and is the hottest part of the earth - temperatures over 5000°C

Question 11

What is the inner core made up of?

Answer 11

It is solid rock which is made up of iron and nickel due to pressure and is very dense (4x more pressure than at the crust)

Question 12

What happens in Plate Tectonics?

Answer 12

• Large plates move in constant, slow motion
• Convection currents move the plates due to radioactive decay deep in the Earth
• The ocean floors always move, spreading from the centre and sinking at the edges

Question 13

What occurs at convergent (plate) boundaries?

Answer 13

Volcanoes and earthquakes

Question 14

What is jigsaw fit?

Answer 14

Where some continents fit together like a geological jigsaw puzzle from when the land was a single continent called Pangea

Question 15

What is continental drift?

Answer 15

The idea that continents are slowly shifting their positions

Question 16

What are convection currents?

Answer 16

They are slow, powerful movements of volcanic rock in the mantle.

Question 17

What happens in convection currents?

Answer 17

The magma is heated to 5000°C in the mantle and rises to the crust where they cool and sink only to be heated again and the process continues indefinitely

Question 18

How is the study of fossils used to explain tectonics?

Answer 18

Similar fossils have been found on different continents, and were not able to cross oceans which means that they must have once lived on the same land mass

Question 19

What is an example of the study of fossils?

Answer 19

Mesosaurus - fossils of the extinct reptile were found in southern Africa and South America despite its habitat of freshwater lakes and the long distance between the two continents

Question 20

How do geological patterns help support plate tectonics?

Answer 20

Similar patterns of rock have been found on different continents such as Australia, South America, Antarctica and Africa

Question 21

What is an example of a geological pattern?

Answer 21

Coal has been found in Antarctica despite it requiring warm climates, which indicates that it was once near the equator

Question 22

How does palaeomagnetism help support plate tectonics?

Answer 22

As lava cools, the magnetic iron points to the north pole, but because the earth’s polarity switches every 100 million years when it reversed from north to south, the iron particles in the magma aligned with the new polarity - this is evidence of seafloor spreading.

Question 23

What is an example of palaeomagnetism?

Answer 23

The Mid Atlantic Range, a range of mountains running along the Atlantic Ocean, were formed by underwater volcanoes and lava cooling