Here's the explanation:
Igneous rocks are formed when magma or lava cools and solidifies. Magma is molten rock that is found beneath the Earth's surface, and lava is molten rock that has reached the surface. Both magma and lava are formed when rocks are heated to very high temperatures, causing them to melt.
The Earth's temperature increases with depth because of the pressure exerted by the overlying rock. This pressure causes the rock to become denser and hotter. As the temperature increases, the minerals in the rock begin to melt, forming magma. The magma then rises to the surface, either through volcanic eruptions or through cracks in the Earth's crust.
If the Earth's temperature did not increase with depth, there would be no pressure to cause the rocks to melt. This means that magma and lava would not be formed, and new igneous rocks could not be formed.
So, the increase in Earth's temperature with depth is a fundamental factor in the formation of new igneous rocks.
