Definition of "metamorphism" [met•a•mor•phism]

• The process by which rocks are altered in composition, texture, or internal structure by extreme heat, pressure, and the introduction of new chemical substances. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Some geologists confine the term metamorphism to the changes involved in contact and dynamic metamorphism, and call the resulting products _metamorphic rocks_."
• "Basically, a process called metamorphism caused the basalts in Shenandoah to recrystallize with new minerals, such as chlorite, epidote, and albite, which help give the rocks their greenish hue."
• "Rocks are not permanent in their condition, but at practically all times and places are undergoing some kind of metamorphism which tends to adapt them to their environment."