Geological process
The transformation of existing rock by heat, pressure and chemically active fluids, without melting. It rearranges minerals and fabrics; a rock that melts is no longer being metamorphosed.
5 of 5 claims on this page cite at least one registered source. Counts describe how each statement is known, not how likely it is to be true.
Each claim states how it is known and cites its evidence.
In contact metamorphism, hot igneous rock intrudes into pre-existing rock which is essentially baked by the heat, changing its mineral structure without the addition of pressure.
Evidence support: Supported by the cited evidence 2 sources, multiple sources, independence unknown
Evidence: U.S. Geological Survey n.d. Primary authority; British Geological Survey n.d. Primary authority
Metamorphic rocks started out as some other rock — igneous, sedimentary, or an earlier metamorphic rock — and have been substantially changed from that original form by high heat, high pressure, hot mineral-rich fluids, or a combination of these.
Evidence support: Supported by the cited evidence 2 sources, multiple sources, independence unknown
Evidence: U.S. Geological Survey n.d. Primary authority; British Geological Survey n.d. Primary authority
The conditions that cause metamorphism are found deep within the Earth and where tectonic plates meet.
Evidence support: Supported by the cited evidence one source
Evidence: U.S. Geological Survey n.d. Primary authority
Metamorphism does not melt the rock. It transforms it into a denser, more compact rock and creates new minerals by rearrangement or by reaction with fluids; a rock that got hot enough to melt would become an igneous rock instead.
Evidence support: Supported by the cited evidence 3 sources, multiple sources, independence unknown
Evidence: U.S. Geological Survey n.d. Primary authority; John 2010 Primary authority; Schulz 2014 Primary authority
The Earth is a dynamic system whose parts are connected, so that changes in one part produce changes in another in a continuous cycle throughout geological time — but a given rock need not pass through every stage in a fixed order.
Evidence support: Supported by the cited evidence 3 sources, multiple sources, independence unknown
Evidence: British Geological Survey n.d. Primary authority; U.S. Geological Survey n.d. Primary authority; U.S. Geological Survey n.d. Primary authority
Record last updated 2026-09-06. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.