1b.1 DM - Constructive Boundaries and Shield Volcanoes

Question 1

How do we work out the type of volcano?

Answer 1

By its cross section

Question 2

What’s the thickest layer of the Earth’s cross section?

Answer 2

Core

Outer core

Question 3

What’s the densest layer of the Earth’s cross section?

Answer 3

Core

Question 4

What is the core made out of?

Answer 4

Iron / Nickel

Question 5

What’s the temperature at the Earth’s core?

Answer 5

4000-5000oc

Question 6

What’s the ‘nature’ / ‘material’ of the mantle? (What’s it made up of?)

Answer 6

Peridotite

Question 7

Where’s the athenosphere?

Answer 7

Top layer of the mantle

Question 8

What’s the temperature of the mantle?

Answer 8

Ranges from 1000-4000oc

Question 9

Where are convection currents generated?

Answer 9

Mantle

Question 10

What’s the temperature of the Earth’s crust?

Answer 10

Ranges from air temperature to 900oc

Question 11

What’s the least dense layer of Earth’s cross section?

Answer 11

Crust

Question 12

What type of volcanoes occur on constructive plate boundaries?

Answer 12

Shield

Question 13

How do volcanoes occur on constructive plate boundaries?

Answer 13

Convection currents cause the plates to move apart

Basaltic (low viscosity / runny) lava is erupted from the fissure

Question 14

What type of lava do you get at a constructive plate boundary / shield volcano

Answer 14

Basaltic
Low viscosity / runny
It runs a long distance before it solidifies

Question 15

What shape are shield volcanoes?

Answer 15

Wide
Short
(Like a shield)

Question 16

What happens at constructive plate boundaries?

Answer 16

Plate move apart (diverge)

Magma/lava erupts from the resulting fissure

Question 17

Why do plates move?

Answer 17

Convection currents cause hot upflowing rock
These weakens the lithosphere
The crust spreads / splits

Question 18

How do convection currents form?

Answer 18

Scientists don’t know for sure.
They think: radioactive isotopes in the core breakdown
This creates heat
Heat initiates the movement of magma in the mantle
The mantle circulates in huge conection currents

Question 19

What are the three main layers of the Earth’s structure?

Answer 19

Core
Asthenosphere, at the top of the mantle
Lithosphere - with the crust at the top

Question 20

How do volcanoes happen at constructive plate boundaries

Answer 20

Convection currents drag plates in opposite direction
Plates pull apart
Hot magma rises from the mantle
The lava is basaltic - thin and runny
It runs a long way before cooling and solidifying