The third layer of the Earth which comes after the Mantle of the Earth is known as the outer core.

Here is a breakdown of the layers of the Earth:
- Crust: The outermost layer of the Earth. It is relatively thin compared to the other layers and consists of solid rock. The crust is divided into two types: continental crust and oceanic crust.
- Mantle: The layer beneath the crust. It is the thickest layer of the Earth and is composed of solid rock that is capable of flowing under high pressure and temperature. The mantle is further divided into the upper mantle and the lower mantle.
- Outer Core: The layer that comes after the mantle. It is a liquid layer composed mainly of molten iron and nickel. The outer core is responsible for generating the Earth's magnetic field through the movement of electrically conductive materials.
- Inner Core: The innermost layer of the Earth. It is a solid sphere composed mainly of iron and nickel. Despite the extremely high temperature, the inner core remains solid due to the immense pressure it experiences.
In summary, the third layer of the Earth which comes after the Mantle of the Earth is known as the outer core.

The third layer of the Earth, which comes after the Mantle, is known as the outer core.

The Structure of the Earth

The Earth is composed of several layers, each with its own unique properties and characteristics. These layers are divided into three main sections: the crust, the mantle, and the core.

1. The Crust:
The crust is the outermost layer of the Earth and is relatively thin compared to the other layers. It is made up of solid rock and is divided into two types: the continental crust and the oceanic crust. The continental crust is thicker and less dense than the oceanic crust.

2. The Mantle:
The mantle is the second layer of the Earth and is located beneath the crust. It is much thicker than the crust and is composed of semi-solid rock. The mantle is responsible for the movement of tectonic plates and plays a crucial role in shaping the Earth's surface through processes such as volcanic activity and earthquakes.

3. The Core:
The core is the innermost layer of the Earth and is divided into two parts: the outer core and the inner core. The outer core is the third layer of the Earth and is located between the mantle and the inner core. It is mainly composed of molten iron and nickel, which gives it a liquid-like consistency. The outer core is responsible for generating Earth's magnetic field.

The Outer Core:

The outer core is approximately 2,300 kilometers thick and surrounds the inner core. It is composed of liquid iron and nickel, along with smaller amounts of other elements such as sulfur and oxygen. The temperature in the outer core is extremely high, reaching up to 5,500 degrees Celsius.

Role of the Outer Core:

1. Magnetic Field Generation:
The outer core is responsible for generating the Earth's magnetic field. The movement of the molten metal in the outer core creates electric currents, which in turn generate a magnetic field. This magnetic field protects the Earth from harmful solar radiation and plays a crucial role in navigation and compass use.

2. Heat Transfer:
The outer core is also involved in the transfer of heat from the Earth's interior to the surface. The heat generated by the inner core is transferred to the outer core through conduction. From there, it is further transferred to the mantle and eventually reaches the surface through processes such as convection and volcanic activity.

In conclusion, the third layer of the Earth, which comes after the mantle, is known as the outer core. It is a liquid layer composed mainly of iron and nickel and plays a vital role in generating the Earth's magnetic field and transferring heat from the Earth's interior to the surface.