The <span>intrusions in the rock layers would be H and J. </span>Intrusions are formed by crystallization of magma infiltrations inside the Earth's crust. These intrusions happen as magma ascends slowly from within the Earth penetrating any space or fissure that it can find. Because this process is so slow, as pressure is released and temperature decreases, magma solidifies and crystallizes into solid intrusive rocks. They are usually the "layers" that brake through others and appear across several other layers in a different orientation than those.
