What is the Earth's crust?

The Earth’s Crust – what’s that about? I mean, are we talking thin crust, deep crust or stuffed crust? Well, basically, it’s the outer layer of the planet – the rocks that make up the land and the seabed, the bit we live on.

How thick is the Earth's crust?

Imagine you’ve painted a football all over with black paint. Believe it or not, that layer of paint is as thick as the crust around our Earth – on the same scale of course! No, really, we live on the Earth’s crust and it seems so big and so thick, but in reality, it’s just a thin layer around the Earth. In some places, like in the deep sea trenches, it’s just 5km thick but in it’s thickest areas, like the vast mountain ranges, it can be up to 60km thick. Sounds a lot, huh? Yeah, for us I guess it is, but when the centre of the Earth is over 6000km beneath your feet, 60km doesn’t seem so far (about 1% of the Journey to the Centre of the Earth!).

Did you know that when we’ve dug mines down through the crust, to get out precious metals like gold, the deepest we’ve ever been able to go is …… 4km! It's a long way from there to the middle of the planet!

What is it made of?

Surprisingly, it’s not made of pizza dough. In fact, it’s made of all those rocks we know – sandstone, granite, and basalt. But hold on...what are they made of? You’re not going to believe this – mainly silcon and oxygen. What? The chemical that goes into computer chips and the gas we breathe? Weird but true! Combined together they make Silicon Dioxide and that makes up most of the rocks and sand all over the world - the Earth’s Crust!

What's under the crust?

Under the crust is the Mantle. That’s molten rock, like lava, that Earth’s Crust is floating on. What, you mean that the solid ground I’m standing on is really floating, like a raft on the ocean? Well, kind of, yes. The crust is made up of jigsaw-type pieces called Tectonic Plates and these move, ever so slowly, floating on the mantle. Sometimes they bash into each other and that causes earthquakes and volcanoes.

So what about earthquakes and volcanoes?

So, the Earth’s Crust is made of pieces that move slowly around the surface of the planet. When the edges of the pieces are moving towards or away from each other, then there’s trouble. The friction of this movement causes a massive shaking of the earth – called an earthquake. Volcanoes are connected to the mantle of lava, under the crust, and when they erupt, molten rock comes pouring out causing mega-destruction.

The Pacific Ocean is where most of the planet’s earthquakes and volcanoes happen. This is due to there being so much tectonic plate movement there - we bet it's an interesting place to live!

Wow! There’s so much to remember so why not check out these EdPlace worksheets to learn more about our wonderful planet!

Year 5 - The Earth and the sun

Year 5 - The Earth, the Sun and the Moon