This glossary of geology is a list of definitions of terms and concepts relevant to geology, its sub-disciplines, and related fields.
For other terms related to the Earth sciences, see Glossary of geography terms (disambiguation).
Also called Indianite.Also called a composite gem.Also called a coccolithophorid.Also spelled dyke.Also spelled gemmology.Also called a gem, fine gem, jewel, precious stone, or semi-precious stone.Also geologic time scale.Also spelled greywacke.Also simply called a lithic.Also spelled luster.Also simply called the Mohs scale.Also called an extensional fault.Also spelled Paleozoic.Also called a thrust fault.Since 1982, officially called titanite by the International Mineralogical Association.Also called scree.Also called glacial till.Sometimes used interchangeably with ultrabasic.Also called the Hercynian orogeny.Also called lignite or brown coal.Also urania.Also called the tensile modulus.