What purpose do the four main layers of the Earth serve?

We have the inner core, outer core, mantle and crust which play an important role on Earth. The layers of the Earth are ... The magma serves to cycle like ball bearings do on an axle , this provides movement ,volacanization heat and earth quakes . To the crust layer . read more

The four main layers of the Earth are the crust, mantle, outer core, and the inner core. The planet Earth was formed about 4.5 billion years ago, after the collapse of the supermassive gaseous body. As time moved on, the Earth cooled down and is still cooling, as of today. read more

Just underneath the Earth’s crust lies a zone called the mantle, a layer about 2,900 km (1,800 miles) thick. The mantle is denser than the crust, having more metallic elements such as iron, calcium and magnesium; at 1,000 degrees Celsius ( 1,800 degrees Fahrenheit) it is also hot enough to remain a soft solid that flows under pressure. read more