metamorphism

noun

meta·​mor·​phism ˌme-tə-ˈmȯr-ˌfi-zəm 

: a change in the constitution of rock

specifically : a pronounced change effected by pressure, heat, and water that results in a more compact and more highly crystalline condition

Examples of metamorphism in a Sentence

Recent Examples on the Web

Magnesite naturally forms in a few ways, like hydrothermal metamorphism, where the presence of water at high temperature and pressures changes magnesium-rich rocks like peridotte. —David Grossman, Popular Mechanics, 15 Aug. 2018

The patterns match those seen in the Alps and the Himalayas — zones that seemed to be huge thrust faults, folds of immense proportion, metamorphism at extreme conditions. —Longreads, 12 Mar. 2018

Like many processes that occur at the Earth’s surface, the liberation of sediment from weathering rock is an intuitive process to visualize (compared to something like metamorphism). —Brian Romans, WIRED, 2 Jan. 2012

Word History

Etymology

metamorph(ic) + -ism

Note: The term was perhaps first used in print by the English geologist John Phillips (1800-74) in Treatise on Geology, vol. 1 (London, 1837), p. 118. The Oxford English Dictionary, third edition, states that the word was borrowed from French métamorphisme, and gives 1823 as the earliest date for this word. The date is probably owed to Trésor de la langue française, which cites as a source for this date HUMBOLDT d[an]s Lar. 19e., i.e., Grand dictionnaire universel du XIXe siècle (or Grand Larousse du XIXe siècle), tome 11 (1874). This work has an undated citation from Alexander Humboldt, which can be traced to the first volume of a French translation (Cosmos, essai d'une description physique du monde, 1848) of Humboldt's Kosmos, Entwurf einer physischen Weltbeschreibung (1845). The 1823 date hence seems impossible. The English coinage metamorphism was presumably based on metamorphic, which as a geological term was introduced by Charles lyell in the third volume of Principles of Geology (see metamorphic). The situation seems to have been further complicated when the French geologist Gabriel August Daubrée mistakenly attributed metamorphism to Lyell: "Dès 1825, il [Lyell] résuma par le nome de métamorphisme les changements qu'ont éprouvés, selon la théorie de Hutton, les terrains d'origine sédimentaires sous l'action de chaleur centrale: c'est cette dénomination qui a été depuis lors adoptée" ("Since 1825 Lyell has summarized under the term metamorphism the changes that rock formations of sedimentary origin have undergone from the effect of central heat: it is this name that has been adopted since then")—"Études et expériences synthétiques sur le métamorphisme," (Annales des mines, 5e série, tome 16 [1859], p. 173). See Gabriel Gohau, "Discussion sur le métamorphisme et le magmatisme autour de 1850," Travaux du Comité français d'Histoire de la Géologie, 3ème série, tome 7 (1993), pp. 51-63.

First Known Use

1845, in the meaning defined above