The Earth Objective; To learn about the internal structure and 12 November 201812 November 2018 Objective; To learn about the internal structure and composition of the Earth.

Imagine a journey to the centre of the Earth… 8.1a Inside volcanoes Imagine a journey to the centre of the Earth… First, you travel through 40 km of solid rock – the crust crust

Imagine a journey to the centre of the Earth… 8.1a Inside volcanoes Imagine a journey to the centre of the Earth… Then, nearly 3 000 km of denser solid rock – the mantle mantle

Imagine a journey to the centre of the Earth… 8.1a Inside volcanoes Imagine a journey to the centre of the Earth… Next, 2 000 km of very hot liquid rock – the outer core Liquid iron outer core

Imagine a journey to the centre of the Earth… 8.1a Inside volcanoes Imagine a journey to the centre of the Earth… Finally, more than 1 000 km of solid iron-nickel alloy. Congratulations! You have reached the centre of the inner core. Solid iron inner core

8.1a Inside volcanoes Inside the Earth crust mantle liquid iron outer core solid iron inner core

Structure of the Earth Structure of the Earth

8.1a Inside volcanoes Eruption! Pressure builds up in magma chambers. The pressure forces magma out of the volcano, along with gases, ash and bigger pieces of solid rock.

8.1a Inside volcanoes Magma or lava? Liquid rock under the ground, and in volcanoes, is called magma. Once liquid rock has left the volcano, and is on the surface of the Earth, it is called lava.

Demonstration activity – volcano – wax, sand and water How is this model good to use? How is it like a volcano?

The sand and water represent the Earth’s crust. The wax layer represents the mantle. When the wax melts, it rises because it is less dense than water. The liquid wax represents magma. Some of the wax rises quickly to the surface, imitating a volcanic eruption. It is very runny and spreads out over the surface of the water (usually!) before solidifying. This illustrates how some lava may cover huge areas before solidifying to form rocks. Some of the wax rises through ‘tubes’ of wax, which insulate it from the surrounding cold water and enable it to reach the surface. This happens in nature too. Some of the wax sets very quickly in the cold water, forming strange shapes. These represent rocks formed under the surface.

Tell students they will now make their own model ‘volcanic eruptions’ Tell students they will now make their own model ‘volcanic eruptions’. Read through the instructions on the Activity sheet. Ask pairs to identify two possible risks in the experiment, and to jot down a way of controlling each of these risks.