Three major types of rocks make up Earth’s crust. Igneous rocks are formed when molten rock solidifies. Igneous rocks can be plutonic or volcanic. Plutonic rocks, such as granite, form when magma cools slowly in the depths of the earth. Volcanic rocks, such as basalt, rhyolite, and andesite form when lava cools rapidly on the surface.
[{"rock_types": "granite", "era_formed": "n/a"}]
[{"rock_types": "granite", "era_formed": "n/a"}, {"rock_types": "basalt", "era_formed": "n/a"}, {"rock_types": "rhyolite", "era_formed": "n/a"}, {"rock_types": "andesite", "era_formed": "n/a"}] [{"rock_types": "granite", "era_formed": "n/a"}] [{"rock_types": "Plutonic", "era_formed": "n/a"}, {"rock_types": "Volcanic", "era_formed": "n/a"}]