Intrusive igneous rocks are formed when magma cools and solidifies below the surface of the Earth. There are different types of intrusive igneous rocks such as batholiths, laccoliths, dykes, and sills.
Types of Intrusive Igneous Rocks
Batholiths: Batholiths are formed because of the cooling and solidification of magma below the surface of the Earth. They are generally dome-shaped. They have been exposed to the surface of the Earth because of the action of the agents of erosion.
Laccoliths: When magma is not fully able to reach the crust of the Earth, it solidifies just below the crust. The upper layers of laccoliths are dome-shaped, but the bottom is almost flat.
Sills: When magma is forced to rise, it pushes itself between two layers of rocks and solidifies. The sills are horizontal rocks.
Dykes: When the magma is forced in the upward direction, it fills the cracks and fissures in the existing rocks. It solidifies in these cracks forming dykes. Dykes are often vertical or slanting in position and are often an offshoot of rock.
Necks:Â When the passage of an extinct volcano is filled with magma, it solidifies. This is known as the volcanic neck or plug.
Also, Read Types of Sedimentary Rocks