The Structure of the Earth
The Earth, like an ogre, is made of layers: a solid iron inner core, a liquid iron outer core and a the mantle made of molten rock. Convection currents in the mantle move the liquid around and in turn move around the tetonic plates of the crust, which is solid rock. The movement of these tetonic plates causes earthquakes and the formation of volcanoes.
Earthquakes
We can find out a lot about the structure of the earth from earthquakes. An earthquake produces three types of wave: S waves, transverse waves that can only travel through solids, P waves, longitudinal waves which can travel through liquids, and surface waves that travel around the crust.
From the arrival times of the P and S waves at detectors in various parts of the world, we can find out: 1) How far away the earthquake started 2) That the mantle is very dense because S waves can travel through it. 3) That the outercore is liquid because S waves cannot travel through it. 4) That the density of the Earth increase gradually as you head towards the centre because the seismic waves are refracted (bent) through it. |
Global Warming
The Earth's atmostphere is a cloud of gas that surrounds the globe. It has a top layer called the ionosphere. The atmostphere is full of greenhouse gases such as carbon dioxide which help trap heat from the sun and keep our planet warm.
Some things such as CFCs, deforestation and burning fuels can increase the amount of greenhouse gases in the atmosphere. This means that the Earth's temperature will slowly increase.
Some things such as CFCs, deforestation and burning fuels can increase the amount of greenhouse gases in the atmosphere. This means that the Earth's temperature will slowly increase.