The Restless Earth

Question 1

Core

Answer 1

At the earths core, the temperature will be over 6000 degrees C. It is believed to be made out of iron and nickel, with a liquid core surrounding a solid inner core. The outer core is about 1200km deep and the inner core around 2200km deep.

Question 2

Mantle

Answer 2

This is the thickest layer (2900km) it is made of silicate rocks that remain molten in the high temperatures (3500 degrees C) and flow it move about. These layers can be known as asthenosphere.

Question 3

Crust

Answer 3

This is a thin layer (5 to 7km deep). The crust and some of the more solid mantle are sometimes known as the lithosphere.

Question 4

How do convection currents cause plate movement

Answer 4

Convection currents occur in the mantle. These currents are caused by radioactivity decay in the core. The extreme heats this creates caused the mantle rock to melt. As rock becomes liquid, it becomes less dense than the material above it and starts to rise to the surface. This movement causes the plates to move towards or away from the heat source (core) so it becomes more dense and sinks back deeper into the mantle where it will become heated again.

Question 5

Continental plates

Answer 5

Thick plates (35-100km) that form from land masses/ continental areas.

Question 6

Ocean plates

Answer 6

Usually thinner plated (6-10km) that form at the bottom of ocean floors.

Question 7

Constructive plate margin

Answer 7

Plates pull apart by the convection currents in the soft rock. Magma rises between them forming small volcanoes on the ocean floor it hardens to basalt, Which form new ocean floor so the ocean floor is spreading about 2.5 cm per year. Landform: mid-ocean ridge.

Question 8

Example of a constructive plate margin

Answer 8

Mid Atlantic ridge Iceland.

Question 9

Deconstructive plate margin

Answer 9

The nasca plate is heavier (oceanic crust is heavier) so it gets pushed down at an ocean trench (subdued- pushed down).
The rock jolts and grinds its way down, causing earthquakes. At the same time, it heats up. Some rock melts its way through the Andes to form a volcano.
Landform: subduction zone, ocean trench.

Question 10

Example of a destructive plate margin

Answer 10

Nevado del ruiz, Columbia.

Question 11

Collision plate margin

Answer 11

The crust gets pushed and folded upwards to form a mountain range. The mountain of the rock causes earthquake. But no rock gets pushed down and melted, so no volcanos.
Fold mountains.

Question 12

Example of collision plate margin

Answer 12

Himalayan mountains.

Question 13

Conservative plate margin

Answer 13

Parts of the plates get stuck, they lurch free. This causes earthquakes. But no rock get pushed down & melted, so no volcanos. Landform: fault lines.

Question 14

Example of conservative plate margin

Answer 14

San andreas fault, California.

Question 15

Earthquake definition

Answer 15

A term or starting in the crust which causes the shaking to be felt in the earths surface.

Question 16

Volcano definition

Answer 16

A cone shaped mountain built up from hardened ash and lava, from which molten material erupts onto the earths surface.

Question 17

Subduction zone

Answer 17

An area where crust is being forced down into the mantle.

Question 18

Mid- ocean ridge definition

Answer 18

Where two plates made of oceanic crust move apart, the magma of the mantle rises to fill the gap, causing the crust to rise and form a ridge.

Question 19

Fold mountains definitions

Answer 19

When the crust of a continental plate folds and buckles upwards.

Question 20

Ocean trench definition

Answer 20

When oceanic crust is forced down (subducted) into the mantle and sinks below normal level to create a deep trench in the ocean.

Question 21

Fault line definition

Answer 21

A weak line in earths surface, where crust is moving, causing earthquake activity.

Question 22

Examples of igneous rocks

Answer 22

Basalt & granite.

Question 23

Examples of sedimentary rocks

Answer 23

Limestone & sandstone.

Question 24

Examples of metamorphic rocks

Answer 24

Slate & marble.

Question 25

How are igneous rocks formed

Answer 25

Formed from cooling and solidifying of magma. Molten rock is called lava on the surface. Extrusive - on the surface crystals are usually evident in the rock. However, if the rock cools quickly as the lava hardens on the surface there will be little evidence of crystals (basalt) if the magma is cooled slowly underground then crystals are more evident (granite)