Plu·ton·ic a.
1. Of or pertaining to Pluto; Plutonian; hence, pertaining to the interior of the earth; subterranean.
2. Of, pertaining to, or designating, the system of the Plutonists; igneous; as, the Plutonic theory.
Plutonic action Geol., the influence of volcanic heat and other subterranean forces under pressure.
Plutonic rocks Geol., granite, porphyry, and some other igneous rocks, supposed to have consolidated from a melted state at a great depth from the surface. Cf. Intrusive rocks, under Intrusive.
Plutonic theory. Geol. See Plutonism.
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In·tru·sive a. Apt to intrude; characterized by intrusion; entering without right or welcome.
Intrusive rocks Geol., rocks which have been forced, while in a plastic or melted state, into the cavities or between the cracks or layers of other rocks. The term is sometimes used as equivalent to plutonic rocks. It is then contrasted with effusive or volcanic rocks.
-- In*tru*sive*ly, adv. -- In*tru*sive*ness, n.
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