1.1.1 Igneous rocks
Figure 1.1 Igneous rocks
Igneous rocks are defined as having formed from a molten state; that is, when liquid rock (called ‘magma’) cools to form a solid rock. Cooling of magma can happen deep inside huge mountain chains such as the Andes, where granite might form. When the magma rises towards and through the Earth’s surface, to produce a volcanic eruption, rocks such as basalt, rhyolite (volcanic glass) and even pumice can be produced.
OpenLearn - An Introduction to Geology
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