Igneous rock

Igneous rocks, which make up most of the continental and oceanic rocks, are formed when magma cools and solidifies, resulting in two possibilities: plutonic rocks and volcanic rocks.

Plutonic rocks

When the process occurs in the depths of the Earth, we refer to plutonic rocks, also called "intrusive rocks". When it occurs at the surface of the planet, we speak of volcanic rocks, also called "extrusive rocks" or "effusive rocks".

Igneous rocks

The commonest igneous rocks are granite (plutonic rock) and basalt (volcanic rock). The former represents 95 % of plutonic rocks and the latter represents 90 % of volcanic rocks.