Theme C: The Restless Earth Revision Summary

1. Plate tectonics theory

1.1 The structure of the earth

1.2 How do convection currents move plates?

1.3 Plate margins - processes

and landforms Direction of

movement

Landforms Processes producing these landforms

Constructive

Destructive

Section Characteristics (what it’s like)

Core

Mantle

Crust

Learning Outcomes – by the end of this section, you should be able to

• describe the structure of the Earth (core, mantle, crust);

• know that the Earth’s crust is made up of a number of plates • understand how convection currents cause plate movement;

How do convection currents actually

move the plates?

By three means:

o ____________between the convection

current and the bottom of the plate

o as the colder, denser plate sinks

(or_________) into the mantle, it

pulls the rest of the plate along

(______________________)

o as new magma seeps up into the crust,

it pushes the plates apart (_____________________)

Learning Outcomes – by the end of this section, you should be able to

• show knowledge and understanding of the processes and landforms associated with following plate margins:

(1) destructive plate margins and subduction zones & ocean trenches (2) collision zones and fold mountains (3) constructive plate margins and mid-ocean ridges (4) conservative plate margins and fault lines.

Collision zone

Conservative

2. Tectonic activity in the British Isles

2.1 Tectonic features in our own back yard Feature What it’s like How it’s formed

Lava Plateau

Basaltic columns

Volcanic plug

2.2 Earthquakes in the British Isles

: Dudley Earthquake, 2002

How was it caused?

What were its impacts?

Learning Outcomes – by the end of this section, you should be able to

• show knowledge and understanding of the characteristics and formation of: lava plateau; basaltic columns;

volcanic plug • the causes and impacts of the Dudley earthquake, 2002, an earthquake in the British Isles

3. Earthquakes - can they be managed?

3.1 Earthquakes - where and how?

• The definition of an earthquake is ___________________________________________________________

______________________________________________________________________________________

• How do earthquakes occur?

• The focus is ____________________________________________________________________________

whereas the epicentre is __________________________________________________________________

• Earthquakes are measured using ___________________ and their size is classified using the ___________

scale.

• Most major earthquakes are found _______________________________________ plate margins.

3.2 The physical consequences of earthquakes

Tsunamis are caused when the earthquake moves the plates and seabed __________________, lifting

it several metres, sending the wave out from the epicentre.

Their characteristics change as they enter shallow water:

Liquefaction occurs when the shaking causes the grains of soil to ____________________ with each

other and instead become surrounded with water. This makes the ground act like a _______________

liquid, and buildings may collapse.

After the shaking, the ground becomes _____________ again.

In deep water… …at the shore

Wave length

Wave height

Speed

Learning Outcomes – by the end of this section, you should be able to • understand the global distribution and causes of earthquakes in relation to plate boundaries; • know and understand that there may be physical consequences of earthquakes:

– liquefaction; – tsunami;

• know and understand the causes and impacts of earthquakes and evaluate the management responses using two case studies (one in an MEDC and one in an LEDC): – identify the plates involved; – describe the short and long term impacts on people and the environment; – evaluate the management response to earthquakes including

o prediction/precautions before the event and o immediate and long term strategies implemented after the event.

3.3 Earthquakes - causes, impacts & management response

Loma Prieta, 1989

Causes Last major earthquake prior to 1989 was in

_____________ (measuring ____ ). Since

then, the ________________ &

___________________ plates moved in

different directions, but ________ at the plate margin � build up of ____________,

causing plates to slowly ___________. Then,

in October 1989, all the pressure was

suddenly released in a massive __.9

earthquake (epicentre at ____________).

The ________________ & ___________________

plates moved in different directions, but ________ at the plate margin � build up of ____________, causing

plates to slowly ___________. Then, in _________, all

the pressure was suddenly released in a massive ____ earthquake whose epicentre was at ____________.

Impacts • Short term

• Long term

• Short term

• Long term

Management

response

• Predictions

• Precautions

• Response

o Immediate

o Long term

• Predictions

• Precautions

• Response

o Immediate

o Long term

• Differences in the impacts of earthquakes in MEDCs and LEDCs

Similar sized earthquakes cause less damage in MEDCs than LEDCs because LEDCs are ___________. This

means they can spend less money on strategies to prepare for earthquakes, such as…

4. Rock Types

Rock type How it’s formed

Igneous o Granite (Intrusive)

o Basalt (Exstrusive)

Sedimentary

o Sandstone

o Limestone

Metamorphic

Learning Outcomes – by the end of this section, you should be able to • understand the formation and basic characteristics of the following rock types:

– igneous – basalt and granite

– sedimentary – limestone and sandstone – metamorphic – marble and slate

Key Terms

Key Terms

Definition questions are common in the exam. Typically, they are worth 2 marks, which means you’ve got to

make two points in your answer. Use the following table to help you complete definitions with two points for

each of the following key terms (one has been completed for you as an example):

Key term 1st point 2nd point Core This is the central part of the earth. It is divided into a solid inner core and liquid

outer core.

Mantle

Crust

Convection current

Plate

Plate margin

Volcano

Volcanic plug

Lava plateau

Earthquake

Richter Scale

Seismograph

Epicentre

Focus

Liquefaction

Tsunami