Question

How do volcanic eruptions create rock?

Answer 1

Answer:

Once the Magma has cooled of it will turn into hard solid rock (or if you put cold water on it)

It has also created our different islands that we have today because of volcanoes.  

Explanation:

Hope that helps

Answer 2

Answer:

magma is sometimes pushed up toward the surface, notably during volcanic eruptions. As it cools, the magma solidifies in the form of magmatic rocks such as basalt. So the rocks of Earth's crust are constantly being transformed as part of the geological cycle that lasts millions of years.