what are igneous intrusions
Igneous intrusions are any igneous rock which hardens underground. There are 6 types of igneous intrusions: 1. A sill is an igneous intrusion that cuts between rock layers. An easy way to remember is that it is horizontal, like a window sill. 2. A dike is an igneous intrusion that cuts across rock layers.gneous intrusions are any igneous rock which hardens underground. There are 6 types of igneous intrusions: 1. A sill is an igneous intrusion that cuts between rock layers. An easy way to remember is that it is horizontal, like a window sill. 2. A dike is an igneous intrusion that cuts across rock layers.