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| Question | Answer |
| What is lithosphere? | The outer layer of the Earth is called the lithosphere. This layer is (relatively) cold and rigid and comprises the crust and top part of the mantle. |
| What is the lithosphere made of? | The lithosphere is made of tectonic plates which are less dense than the mantle below. |
| The crust is too thick to drill through, so where is most of our information about the Earth? | The crust is too thick to drill through, so most of our information about the Earth is collected from seismic waves produced by earthquakes and man-made explosions. |
| What is the mantle? | The mantle is the zone between the core and the crust. It is cold and rigid just below the crust, but at greater depths it is hot and non-rigid and able to move. |
| The Earth's core transfers energy, so ....... | The Earth's core transfers energy, so the temperature of the mantle increases with depth. |
| What do convection currents do? | Convection currents slowly move tectonic plates. |
| What is subduction? | Oceanic crust is denser than continental crust. When these plates collide, the oceanic plate (which is cooler at the margins) sinks, pulling more of the plate down, and partly melting as it reaches the hotter part of the mantle. This is called subduction. |
| Most scientists now accept the theory of plate tectonics, which suggests that South Africa and South America could once have been one land mass. Explain why. | - It explains a wide range of evidence - It has been discussed and tested by many scientists |
| Whose theory was not accepted by scientists at the time? | Wegener's continental drift theory (1914) was not accepted by scientists at the time. |
| What evidence was found in the 1960s? | In the 1960s, new sea floor spreading evidence was found. Subsequent research led to Wegener's theory slowly becoming accepted. |
| Why does magma rise up through the Earth's crust? | Magma rises up through the Earth's crust because it is less dense than the crust. |
| What can this cause? | This can cause volcanoes. |
| Magma can have different types of composition which cause different types of eruption. Why do geologists study volcanoes? | Geologists study volcanoes to try to forecast future eruptions and reveal more about the structure of the Earth. Geologists are better able to predict eruptions than they used to be, but still not with 100% certainty. |
| What types of rock are formed from lava? | Different types of igneous rock are formed from lava. |
| Where does iron-rich basalt rock come from? | Iron-rich basalt rock comes from runny lava in slower volcanic eruptions. |
| Where does silica-rich rhyolite rock come from? | Silica-rich rhyolite rock comes from thick lava in explosive eruptions. |
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