Crust
The crust is the smallest layer of the earth it is 5-50km thick. It is the coldest layer on the earth being 0 degrees. Did you know the crust is the only place on earth that we could live on, the rest is to hot and we could not get any food. Crust means outside of something, in this case it is the outside of the earth. Bread for instance has crust on the outside and is the smallest part on the bread. The crust of the earth is made out of rock because it is very solid and harder to move. The crust is the smallest layer but is still very thick. No person has ever made a hole that has gone through the crust. The places we live are on the crust.
Mantle
The mantle is the biggest layer in the earth. About 2900 km thick . The mantle is about 3700 degrees Celsius. It would not be a good place to live. The mantle is split up into two parts the upper and lower mantle. The mantle is also semi solid, it has molasis like substance that when hits the outer mantle gets colder so it goes down. But when it gets back into the inner mantle it gets hot again so it rises up and keeps going in this pattern this equils the convection currents. It is the second layer in and the biggest layer. Read more on a spasific layer on the mantle. On the picture to the left there are convection currents the lower mantle gets the substance to rise and the upper pushes it back down. Look at the clip below for a better under standing.
Inner and Outer mantle
The outer mantle is cold. It is made up of a molassis like substance which is made out of iron and nickel. When this substance hits the inner core it heats up. When the substance gets into the outer mantle it gets cold again then goes back down. The reason why is goes back down is because when something gets cold the particles inside gain weight, therefor pushing it down. When the substance hits the inner core it heats up which make the partcles lose weight which make them rise. When they keep a steady flow of getting hot then cooling down and it keeps repeating it's self it is called a convection current. The inner mantle is bigger then the outer core. But the inner mantle is hotter because it is closer to the inner core so the inner mantle is hotter.
Outer Core
The outer core is 1400 miles thick and is made out of iron and nickel. It is also the second smallest layer of the earth. It is the one of the most solid layers because of the weight pushing down on it. It is extremely hot because the layer under it is the main heat of the earth. Fun fact on the outer core is that the outer core in 85% made out of almost liquid iron and 5% nickel and the rest is soil.
Inner Core
The inner core is the second smallest layer. The inner core is the most inner layer of the earth and the most solid because all the weight in the world is pushing down on a layer. This layer is only about 1216 km thick. Most of the earths heat comes from the inner core. Believe it or not Tthe inner core is the same temperature as the surface of the sun.