Laccoliths are blister-like intrusions, usually near the surface, that form when magma pushes overlying layers upward. Lopoliths are mega-sills, usually of gabbro or diorite, that may cover hundreds of square kilometers and be kilometers thick. They often have a concave structure and are differentiated. That is, they take so long to harden that heavy minerals have a chance to sink and light minerals can rise. Discordant intrusions cut across layers.
Dikes are thin sheets of magma intruded into fractures in the crust.
Stocks or plutons are small irregular intrusions Batholiths are usually granitic and cover hundreds or thousands of square kilometers. In the above diagram, non-batholithic rocks are shown in light blue. Geological cross-sections often show batholiths as extending downward indefinitely. In fact, geophysical techniques and field observations suggest that most batholiths are thick lenses 10 km thick or so. Many batholiths have some of the former roof rocks still present as roof pendants .