The correct answer is Batholiths. Key Points - The lava that is released during volcanic eruptions on cooling develops into igneous rocks. - Depending on the location of the cooling of the lava, igneous rocks are classified as volcanic rocks (cooling at the surface) and plutonic rocks (cooling in the crust). - The lava that cools within the crustal portions assumes different forms called intrusive forms. They are: - Batholiths - A large body of magmatic material that cools in the deeper depth of the crust develops in the form of large domes. - They appear on the surface only after the denudational processes remove the overlying materials. - They cover large areas, and at times, assume depth that may be several km. - Batholiths are the cooled portion of magma chambers. - Lacoliths - These are large dome-shaped intrusive bodies with a level base and connected by a pipe-like conduit from below. It resembles the surface volcanic domes of composite volcano, only these are located at deeper depths. It can be regarded as the localised source of lava that finds its way to the surface. - Lapoliths As and when the lava moves upwards, a portion of the same may tend to move in a horizontal direction wherever it finds a weak plane. In case it develops into a saucer shape, concave to the sky body, it is called lapolith. - Phacoliths A wavy mass of intrusive rocks, at times, is found at the base of synclines or at the top of anticline in folded igneous country. - Such wavy materials have a definite conduit to source beneath in the form of magma chambers. These are called the phacoliths.