What is Laccolith? How it is formed?

A large amount of Igneous Rock under the surface of earth, often attaining the size of a mountain is known as Laccolith. It is produced by the intrusion of Magma from below, into the crust of the lithosphere without reaching the surface, the surface strata being arched up over the intrusion.

Well-formed laccoliths possess a flat bottom and a dome-shaped upper surface, and occur often very irregular.