Etymology
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geological (adj.)
1791, from geology + -ical. Related: Geologically.
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formation (n.)

late 14c., "vital force in plants and animals;" early 15c., "act of creating or making," from Old French formacion "formation, fashioning, creation" (12c.) or directly from Latin formationem (nominative formatio) "a forming, shaping," noun of action or condition from past-participle stem of formare "to form," from forma "form, shape" (see form (n.)). Meaning that which is formed or created" is from 1640s. In geology, "group of rocks having a similar origin or character," 1815. Related: Formational.

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re-formation (n.)

"act of forming anew, a second formation," early 15c., from re- "back, again" + formation. The hyphenation is from 17c. to keep it distinct from reformation, as is the full pronunciation of the prefix.

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back-formation (n.)

also back formation, "word formed from an existing word, often by removal of a suffix or supposed suffix," by 1887, from back (adv.) + formation.

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subduct (v.)
1570s, "subtract," from Latin subductus, past participle of subducere "to draw away, take away" (see subduce). Geological sense is from 1971, a back-formation from subduction. Related: Subducted; subducting.
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orogeny (n.)

1883, "mountain-forming, the formation of mountains," from French orogénie; see oro- + -geny. In reference to particular mountain-building geological periods, by 1914. Related: Orogenic (1886); orogenesis (1886).

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erode (v.)

1610s, "gnaw or eat away" (transitive), a back-formation from erosion, or else from French éroder, from Latin erodere "to gnaw away, consume," from assimilated form of ex "away" (see ex-) + rodere "to gnaw" (see rodent). Intransitive sense "become worn away" is by 1905. Related: Eroded; eroding. Originally of acids, ulcers, etc.; geological sense is from 1830.

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Jurassic (adj.)
"of or pertaining to the geological period between the Triassic and the Cretaceous," 1823, from French Jurassique, literally "of the Jura Mountains," between France and Switzerland, whose limestones were laid down during this geological period. The name was chosen by von Humboldt. As a noun from 1831. The name is said to be from Gaulish *iuris "wooded mountain."
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Paleozoic (adj.)

in reference to the geological era between the Precambrian and the Mesozoic, a geological series characterized by the earliest record of modern life forms, 1838, coined by Adam Sedgwick (1785-1873) from paleo- "ancient" + Greek zoe "life" (from PIE root *gwei- "to live") + -ic.

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catastrophism (n.)

as a geological or biological theory (opposed to uniformitarianism), 1869, coined by T.H. Huxley from catastrophe + -ism. Related: Catastrophist.

By CATASTROPHISM I mean any form of geological speculation which, in order to account for the phenomena of geology, supposes the operation of forces different in their nature, or immeasurably different in power, from those which we at present see in action in the universe. [Huxley, "Address" to the Geological Society of London, Feb. 19, 1869]
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