intrusive « Back to Glossary IndexIgneous rock cooling, and thus forming, inside of the Earth, i.e. under the surface. Synonyms: plutonic rock, plutonicRelated Articles: 16 Energy and Mineral ResourcesGlossary: batholithGlossary: plutonGlossary: layered intrusionGlossary: felsic« Back to Glossary Index Author: Chris Associate Professor, Salt Lake Community College, Salt Lake City, Utah View all posts by Chris