The Restless Earth

Question 1

What are the two types of tectonic plates?

Answer 1

Oceanic

Continental

Question 2

What are the five differences between the two types of tectonic plates?

Answer 2

Oceanic : Continental
5km thick : 30km thick
More dense : Less dense
Young - less than 200 million : old - Over 1500 million years
Sinks : Cannot sink
Can be destroyed and made : Cannot be destroyed and made

Question 3

What are the four layers of the earth?

Answer 3

Crust
Mantle
Outer core
Inner core

Question 4

What is the name of Wegner’s theory and what is it?

Answer 4

Wenger’s theory of continental drift

In 1912 he came up with the idea that all the continents were once connected to make one super continent called Pangaea

Question 5

Why was Wenger’s theory originally rejected?

Answer 5

No one could understand how the continents had drifted apart

Question 6

What evidence is there to support Wegner’s theory?

Answer 6

Similar species on both sides of the Atlantic (Primates)
The west coast of Africa looks like it could fit into the east coast of South America
Matching rock formations and mountain chains found in Africa and South America
Fossil plants in India, South Africa, Australia, Antarctica and South America are similar to each other
Similar fossils found in South America and Africa (mesosaurus)

Question 7

What are the four types of plate boundaries?

Answer 7

Destructive - Subduction
Destructive - Collision
Constructive
Conservative

Question 8

Describe what happens, the tectonic activity and give an example of a subduction boundary

Answer 8

This is where a less dense (oceanic) plate sub ducts beneath a more dense (continental) plate, it is the oceanic plate because it can be destroyed.
This build up of pressure and then the sudden release causes an earthquake and there is space for magma to force its way up and create volcanoes because the friction and heat from the mantle melts the rock.
An example of this is the Andes in South America, the Nazca plate sub ducts beneath the South American plate.

Question 9

Describe what happens, the tectonic activity and give an example of a collision boundary

Answer 9

The is where two continental plates collide with each other and pressure builds up until there is enough to cause them to buckle upwards creating fold mountains, neither can overpower the other as thy are the same density.
The huge, sudden release of pressure causes huge earthquakes however, due to there being no space for magma there are no volcanoes.
An example of this is the Himalayas, the African and Eurasian plates push against each other.

Question 10

Describe what happens, the tectonic activity and give an example of a constructive boundary

Answer 10

This is where two plates move apart from one another (usually beneath an ocean). It is common for volcano islands to be created in the gap left by the two plates.
Volcanoes are formed at this boundary as there is no magma to stop the magma from erupting, earthquakes also occur.
Surtsey is an example of a volcanic island and is found in the mid Atlantic ridge which was created due to the North American and Eurasian plates moving apart.

Question 11

Describe what happens, the tectonic activity and give an example of a conservative boundary?

Answer 11

This where two plates move alongside each other either in the same direction, one moving faster or in opposite directions.
Earthquakes occur here when the plates collide pressure builds up and when it is released this causes the quake.
An example of this is the San Andreas Fault Line in California where the North American and Pacific plates are constantly colliding with one another. They collide together because they move at different angles rather than being parallel.

Question 12

Why do the tectonic plates move and how many major ones are there?

Answer 12

Convection currents in the mantle

14

Question 13

What are the highest and lowest points on earth?

Answer 13

Mt. Everest 8850ft above sea level

Challenger Deep Marianas Trench 11,033M beneath sea level

Question 14

How are fold mountains formed?

Answer 14

They are formed at either one of the destructive boundaries.
A geosyncline (a huge depression in the earth) has rivers carrying sediments flow into it.
The sediments begin to build up in layers at the bottom of the geosyncline which will now be filled with water (sea).
Due to the pressure of the sediments and water above the bottom layers compress into ‘soft’ rock such as limestone and sandstone, this takes millions of years.
When the two plates push together it forces the sedimentary rock to buckle upwards as it has nowhere else to go.
This creates the fold mountains such as the Himalayas or the Alps

Question 15

What two trends do ocean trenches follow?

Answer 15

They are all situated around the Pacific Ocean and they are all situated next to fold mountains
Eg. The Chile trench is next to the Andes

Question 16

How are oceanic trenches formed?

Answer 16

They are formed at subduction boundaries.
It is the point at where the oceanic plate has sub ducted beneath the continental plate that the ode I’d trench is formed at

Question 17

What case study is used for an example of people using fold mountains and what four things are they used for?

Answer 17

The Andes
Farming
Hydroelectric Power
Mining
Tourism

Question 18

How are the Andes used for farming?

Answer 18

Crops are grown by subsistence famers (rely on themselves)
Terraces are used to make flat land for the crops to go on the mountains - flat areas retain water and limit downed movement of soil
Potatoes are grown in Bolivia
Crops grown in lower valleys mostly
Cash crops grown: soybeans, rice and cotton (crops produced for their value rather than for using them)
Male llamas used to carry materials can carry over 25% of their weight (50kg)
Female llamas used for meat, wool and cotton

Question 19

How are the Andes used for mining purposes?

Answer 19

Andean countries are ranked in the top 10 tin, nickel, silver and gold exported.
More than half of Peru’s exports are mining.
Yanacocha gold mine is the biggest in the world, USA owns 51% of it.
Gold extracted by loosening it with daily dynamite blasts then spraying it with cyanide.
This causes water pollution.
The mine is located in Cajamarca, Peru who’s population went from 30,000 to 240,000 after the mine was opened.
This increased crime rates.

Question 20

How do people use the Andes for hydroelectric power?

Answer 20

The steep slopes are good for H.E.P
Easily dammed, flow of water generates electricity.
Melting snow in water increases water.
El Platinal constructed in 2009, second largest in Peru dams the Cañete river

Question 21

How do people use the Andes for tourism?

Answer 21

There are many natural attractions like: mountain peaks, volcanoes, glaciers and lakes.
They use the Inka Trail as well which is a 45km over 4 days that ends with Machu Picchu.
There are also over 250 species of orchid on the Inka Trail

Question 22

What is the difference between a natural hazard and a natural event?

Answer 22

A natural hazard has to be a threat to humans and damages human lives or properties.
A natural event is something that occurs in a place where no one is effected eg. Volcano in the middle of an ocean (Surtsey).

Question 23

What are the names, the differences and an example of the two types of volcanoes?

Answer 23

Composite : Shield
Subduction boundary : Constructive boundary
Narrow base : Wide base
Steep slopes : Gentle slopes
Layers of lava and ash build up on the slopes : Runny lava
Infrequent eruptions : Frequent eruptions
Violent eruptions : Non-violent eruptions
Volcanic booms : Little ash
High, pointed peak : Low, rounded peak
Secondary cones : None
Popacatepeh, Mexico : Nyiragongo, Democratic Republic of Congo

Question 24

Shield volcano in an LDC case study

Answer 24

Where: East African Rift Valley in the Democratic Republic of Congo
When: 17th January 2002
Plate: Crack in the African Plate
Why: The rift in the African plate acts like a constructive boundary so there is space for the magma to flow through the crust, this makes it a shield volcano
Primary Effects: The lava destroyed the airport and split the town of Goma in half. It destroyed many homes, roads and water pipes. It also set off explosions in power plants.
Secondary Effects: Due to the airport being destroyed no planes could land/take off which meant that no widely be received from other countries, half a million people fled to Rwanda. The exploding power plant meant there was no power and people had to sleep in the streets because their homes were destroyed. The people had no access to clean water so they drunk dirty water which meant water borne diseases such as cholera became a risk.