4 Layer On layer The crust is up to 40,3 miles thick The upper mantle is 447 3 miles thick The lower mantle is 1348,9 miles thick The inner core is 758,6 miles thick The outer core is 1403,6 miles thick Our Earth is the rock on which we live It may seem pretty stable when we’re standing on it but it’s not a solid piece of rock In fact some of it is a churning boiling mass of red hot liquid rock that is constantly on the move We may only see the rocky crust but there’s lots going on inside Layers When you stand on hard ground you might think that the planet youTre standing on is one solid ball But it isnTt ItTs made up of layers The hard bit you stand on is the outer layer called the crust Underneath is the upper mantle a plastic-like solid that is actually close to melting point Below that is the lower mantle of dense mostly solid rock Scientists think the core is made of solidly-packed metals The liquid outer core is mainly iron and nickel while the solid inner core is mainly iron The temperature here is around 10,832ºF at the core but the weight of the layers above presses the material together so hard that it has become solid
Pangaea WeTre used to seeing the continents on maps in a fixed position But the continents arenTt fixed at all At one time 225 million years ago the continents made up just one great landmass Scientists call this landmass Pangaea or all EarthT Around 100 million years ago the continents began to split apart Forty million years ago they looked pretty much as they do today 5 KEY WORDS crust core mantle iron nickel tectonic plate continent 225 million years ago the Earth’s continents were starting to break away from the single landmass known as Pangaea Over millions of years the continents split apart Today the continents form the familiar shapes we see in atlases TectOnic plates The continents split apart because they are part of the ever-moving jigsaw of plates that make up the EarthTs crust These plates known as tectonic plates can collide into one another move apart from one another or slide past each other At one of its edges where plates are moving apart a plate can grow as magma rises up out of the mantle below At the same time another edge is destroyed either by sinking down under its neighbour plate or by being pushed up to make mountain chains 8 to 12 large plates and about 20 smaller ones make up the EarthTs crust
6 A giant magnet Geographic North Pole You can think of the Earth as having a gigantic bar magnet buried inside The Earth’s magnetic field pulls objects towards it in the same way as the bar magnet Although we don’t feel it the Earth is spinning around an imaginary line At the top is the North Pole and at the bottom is the South Pole These are the geographic poles The poles are slightly off center because the Earth is tilted at a slight angle N S Winter at the North Pole is extremely cold and ice-locked Magnetic North Pole N S The magnetic field of a bar magnet can be seen if iron filings are placed around it They show the shape of the field It’s strongest at the north and south poles Magnetic pOles Because the outer core of the Earth is fluid iron itTs able to move or flow This movement creates an electric current which in turn creates a magnetic field The imaginary magnet doesnTt run exactly along the EarthTs rotational axis ItTs skewed slightly off center So the magnetic north pole is close to the geographic North Pole and the south magnetic pole to the geographic South Pole
Magnetic field The Earth produces its own magnetic field This is fairly weak on the surface After all the planet Earth is almost 8077,8 miles in diameter so the magnetic field has to travel a long way to affect your compass ThatTs why a compass needs to have a lightweight magnetic needle that spins easily Without this there just isnTt enough strength in the EarthTs magnetic field to turn the needle Gravity Gravity is one of the natural forces ItTs the force that causes matter such as rocks to attract one another ItTs gravity that holds the planets in our solar system in place around our Sun ItTs also gravity that holds the stars in our galaxy in place The strength of the gravitational force depends on the mass of an object You would think that gravity must be a very strong force but in fact itTs quite weak Every time you lift up an object you are overcoming the EarthTs force of gravity 7 A compass needle always points north Metal at the center No one knows for sure but the EarthTs outer core is thought to consist largely of molten iron At the very center of the Earth the pressure is so great that this huge collection of super-hot iron crystallizes into a solid The heat that is It is gravity that holds the planets in our solar system in place around our Sun given off from the inner core spreads in a circular movement following the rotation of the Earth It causes the liquid iron in the outer core to move in a rotational pattern too ItTs thought that these rotating forces in the liquid iron layer create the magnetic forces around EarthTs axis
