PLUTONISM
Etymology
Noun
plutonism (countable and uncountable, plural plutonisms)
The old geological theory that the rocks forming the Earth were formed in fire by volcanic activity, with a continuing gradual process of weathering and erosion, then deposited on the sea bed, re-formed into layers of sedimentary rock by heat and pressure, and raised again.
Synonyms
• vulcanism
Source: Wiktionary
Plu"to*nism, n. Etym: [Cf. F. plutonisme.]
Definition: The theory, early advanced in geology, that the successive
rocks of the earth''s crust were formed by igneous fusion; -- opposed
to the Neptunian theory.
Source: Webster’s Unabridged Dictionary 1913 Edition