Making new rocks from old

Part of Hall of Planet Earth.

Making New Rocks From Old AMNH/R.Mickens

Metamorphism is the process by which rocks re-crystallize into new combinations of minerals in response to changing temperature, pressure, and exposure to hot, reactive fluids. The rocks’ texture and grain size are usually altered as well. Metamorphic rocks are created deep in the roots of mountains. Geologists study these rocks to learn more about mountain building and how the Earth’s crust evolves.

In This Section

Exhibit Metamorphic rock The transformation of one rock to another by heat, pressure, and reactive fluids is the process of metamorphism. Exhibit Transformed rocks In 1893, G. M. Barrow discovered that an extensive layer of rock shows progressive transformation of its mineral content.