The Earth is a ball of diameter about 12,800km, which means a journey of nearly 40,000km all the way round – quite a long way.It’s a little bit like an eggshell. The atmosphere is an incredibly thin protective layer of gas that stops the sun from frying us or us freezing to death, sitting over a thin crust between 30 and 40km thick. The deepest places we’ve been to on the earth are in South Africa, where mining companies have excavated 3.5 km into the earth to extract gold. No one has seen deeper into the earth than the South African miners because the heat and pressure felt at these depths prevents us from going much deeper.
The crust is in the form of plates – called tectonic plates – which once fitted together. Over time, the plates have actually moved huge distances – South America once fitted nicely into West Africa like pieces of a jigsaw puzzle. When earthquakes happen, the rock layers can jolt over each other and the shockwaves can damage buildings and sometimes kill a lot of people. The recent earthquakes in Haiti and Chile caused many deaths and a great deal of damage.
Underneath the crust is the mantle, some of which near the crust is molten. Sometimes, the molten material has to escape and a volcano erupts. It is a much thicker layer than the crust. Beneath that, there’ a core which might even be solid because the pressure is so very high, which contains a lot of iron and nickel – making the Earth a magnet.
Here’s an animation of how the continents moved apart…