Question

C. Give reasons for the following:
1. The volcanic material in some cases reaches the surface while in some other instances a gets deposited
within the rocks of the earth's crust.
2. Volcanic activity is common in areas around marine trenches.​

Answer 1

1.During volcanic eruptions, the lava released on cooling during volcanic eruptions grows into rocks that are igneous. The cooling can occur either when the surface is reached or while the lava is still in the part of the crust.

2.At oceanic ridges most of the crustal movement is near the surface as sea-floor spreading causes plates to move apart and new crust is formed by magma pushing up from the mantle. ... Earthquakes that are deep in the crust are found in the same areas as the deep-sea trenches

Answer 2

Explanation:

2 marine trenches have very thin layer of earth crust

1 the the volcanic material is too hot and pressure is too high it reaches the ground