How do intrusive igneous rocks form?
Intrusive igneous rocks are created when magma pushes up into the Earth’s crust and cools there. Although the decrease in pressure the magma experiences as it rises in the crust allows it to solidify, this is still a fairly slow process, so intrusive igneous rocks tend to have larger grains than extrusive igneous rocks. Granite and Gabbro are both intrusive igneous rocks.
