Question

Why does magma rise from depth to the surface of the Earth? SELECT ALL THAT APPLY

a. It is a liquid, and liquids always float atop solid objects
b. Earth's rotation causes it to accelerate until it reaches the surface
c. It is less dense than the rocks that surround it
d. The surrounding rock creates pressure that pushes magma upward

Answer 1

Magma rises to the surface of the Earth because it is less dense than the surrounding rocks. Different mechanisms, such as heat addition or the addition of volatiles, can cause rock to melt and form magma. Volcanic activity allows magma to reach the surface.

Step-by-step explanation:

Magma rises from depth to the surface of the Earth primarily because it is less dense than the surrounding rocks. The density of the mantle rock increases with depth due to compression from the weight of overlying material, causing it to be more dense than the magma. As a result, the higher-density rocks create pressure that pushes the less dense magma upward.

Additionally, the melting of rock to form magma can occur through different mechanisms. One way is through the addition of heat, which can be caused by mantle plumes generated at the core-mantle boundary. These plumes create regions of increased temperature that can cause melting in the lithospheric region. Another way is through the addition of volatiles, such as water, which lowers the melting temperature of rock and allows it to melt even under high pressures.

These processes can lead to the formation of magma, which can then rise to the surface through volcanic activity.