Which layer of the Earth is liquid?

the outer core. The inner core is solid because of the enormous pressure.

What is the lithosphere?

the crust and the rigid top of the mantle. It is broken into plates.

At which boundary do plates move apart?

divergent (constructive). New crust forms in the gap.

At which boundary are there earthquakes but no volcanoes?

conservative. The plates slide past each other, and no magma is produced. Collision boundaries are the same.

How were the Himalayas formed?

by two continental plates colliding. The crust crumpled upwards into fold mountains.

one plate being forced down beneath another. The denser oceanic plate sinks into the mantle.

The structure of the Earth and plate boundaries · Cambridge IGCSE Geography (9

In plain words

The ground feels solid and still. It is neither. The Earth's surface is a cracked shell, and its pieces are moving, a few centimetres a year, about as fast as your fingernails grow. Almost every earthquake and volcano happens where two pieces meet.

8 things to know

The Earth has layers. The inner core is solid iron and nickel, and the hottest part. The outer core is liquid. The mantle is the thickest layer, made of hot rock that can flow slowly. The crust is the thin, solid outer layer.
The lithosphere is the crust together with the rigid top of the mantle. It is broken into tectonic plates.
Oceanic crust is thin and dense. Continental crust is thicker and less dense.
Plates move because of convection currents in the mantle: hot rock rises, spreads and sinks, dragging the plates.
Divergent (constructive) boundary: two plates move apart, magma rises to fill the gap and makes new crust. There are volcanoes and small earthquakes. Example: the Mid-Atlantic Ridge.
Convergent (destructive) boundary: an oceanic plate meets a continental plate and is forced beneath it (subduction). There are deep ocean trenches, fold mountains, violent volcanoes and strong earthquakes. Example: the Nazca and South American plates.
Convergent (collision) boundary: two continental plates meet. Neither sinks, so the crust crumples up into fold mountains. There are earthquakes but no volcanoes. Example: the Himalayas.
Conservative (transform) boundary: two plates slide past each other. There are earthquakes but no volcanoes. Example: the San Andreas Fault.

Worked example

Explain why there are volcanoes at a destructive plate boundary but not at a collision boundary.

At a destructive boundary the denser oceanic plate is subducted into the mantle, where it melts.
The magma formed is less dense than the rock around it, so it rises through the continental plate and erupts.
At a collision boundary both plates are continental and too light to sink. Nothing is subducted and melted, so there is no magma to erupt.

Tips and tricks

Learn each boundary with its movement, its hazards and an example. Four boundaries, three facts each.
Earthquakes happen at every type of boundary. Volcanoes only where magma can reach the surface: divergent and destructive boundaries.

6 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

The structure of the Earth and plate boundaries: 6 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

Which layer of the Earth is liquid?
- the inner core
- the outer core (the answer)
- the crust
- the lithosphere
The inner core is solid because of the enormous pressure.
What is the lithosphere?
- the liquid part of the core
- the crust and the rigid top of the mantle (the answer)
- the atmosphere
- the oceans
It is broken into plates.
At which boundary do plates move apart?
- divergent (constructive) (the answer)
- convergent (destructive)
- collision
- conservative
New crust forms in the gap.
At which boundary are there earthquakes but no volcanoes?
- divergent
- destructive
- conservative (the answer)
- none
The plates slide past each other, and no magma is produced. Collision boundaries are the same.
How were the Himalayas formed?
- by plates moving apart
- by two continental plates colliding (the answer)
- by a hotspot
- by plates sliding past each other
The crust crumpled upwards into fold mountains.
What is subduction?
- two plates moving apart
- one plate being forced down beneath another (the answer)
- plates sliding sideways
- magma cooling at the surface
The denser oceanic plate sinks into the mantle.

6 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 10 marks. Write your answers on paper, then check them.

The structure of the Earth and plate boundaries

Cambridge IGCSE Geography (9–1) 0976 · 10 marks · papermunch.org

Name ______________________________ Date ______________

Describe the layers of the Earth.[4]
Show answerHide answer
The inner core is solid and very hot. The outer core is liquid. The mantle is a thick layer of hot rock that flows slowly. The crust is the thin, solid outer layer.
I got this one
Describe what happens at a divergent (constructive) plate boundary.[4]
Show answerHide answer
Two plates move apart. Magma rises from the mantle to fill the gap. It cools to form new crust. Volcanoes and small earthquakes occur.
I got this one
Explain why tectonic plates move.[2]
Show answerHide answer
Convection currents in the mantle: hot rock rises, spreads out and sinks, and this drags the plates above along.
I got this one

Answers: The structure of the Earth and plate boundaries

1. The inner core is solid and very hot. The outer core is liquid. The mantle is a thick layer of hot rock that flows slowly. The crust is the thin, solid outer layer.
2. Two plates move apart. Magma rises from the mantle to fill the gap. It cools to form new crust. Volcanoes and small earthquakes occur.
3. Convection currents in the mantle: hot rock rises, spreads out and sinks, and this drags the plates above along.