Editing Subduction (section)

== History of investigation ==
[[Harry Hammond Hess]], who during [[World War II]] served in the [[United States Navy Reserve]] and became fascinated in the ocean floor, studied the [[Mid-Atlantic Ridge]] and proposed that hot molten rock was added to the crust at the ridge and expanded the seafloor outward. This theory was to become known as [[seafloor spreading]]. Since the [[Earth's circumference]] has not changed over geologic time, Hess concluded that older seafloor has to be consumed somewhere else, and suggested that this process takes place at [[oceanic trenches]], where the crust would be melted and recycled into the [[Earth's mantle]].<ref>{{Cite journal |first=J. Tuzo |last=Wilson |date= December 1968 |title=A Revolution in Earth Science |journal=Geotimes |volume=13 |issue=10 |pages=10–16 |place=Washington DC}}</ref>

In 1964, [[George Plafker]] researched the [[1964 Alaska earthquake|Good Friday earthquake]] in [[Alaska]]. He concluded that the cause of the earthquake was a [[Megathrust earthquake|megathrust reaction]] in the [[Aleutian Trench]], a result of the Alaskan continental crust overlapping the Pacific oceanic crust. This meant that the Pacific crust was being forced downward, or ''subducted'', beneath the Alaskan crust. The concept of subduction would play a role in the development of the [[plate tectonics]] theory.<ref>{{cite press release|author=Geological Society of America|author-link=Geological Society of America|title=Geological Society of America honors Excellence in Geoscience for 2017|url=https://www.eurekalert.org/pub_releases/2017-07/gsoa-gso070617.php|publisher=[[American Association for the Advancement of Science|Eurekalert!]]|date=July 6, 2017}}</ref>

First geologic attestations of the "subduct" words date to 1970,<ref>{{cite encyclopedia | title=subduction | encyclopedia=Online Etymology Dictionary | url=https://www.etymonline.com/word/subduction?ref=etymonline_crossreference | access-date=31 December 2020}}</ref> In ordinary English ''to subduct'', or ''to subduce'' (from Latin ''subducere'', "to lead away")<ref>{{cite encyclopedia | author1=John Ogilvie | author2=Charles Annandale | title=Subduce, Subduct | encyclopedia=Imperial Dictionary of the English Language | edition=New Edition Carefully Reviewed and Greatly Augmented | volume=IV Scream-Zythus | year=1883 | location=London | publisher=Blackie & Son | url=https://books.google.com/books?id=PYICAAAAQAAJ&dq=English+dictionary+subduct&pg=PA237}}</ref> are [[transitive verb]]s requiring a subject to perform an action on an object not itself, here the lower plate, which has then been ''subducted'' ("removed"). The geological term is "consumed", which happens the geological moment the lower plate slips under, even though it may persist for some time until its remelting and dissipation. In this conceptual model, plate is continually being used up.<ref>{{cite web | title=What is a tectonic plate? | year=1999 | publisher=United States Geological Survey (USGS) | url=https://pubs.usgs.gov/gip/dynamic/tectonic.html}}</ref> The identity of the subject, the consumer, or agent of consumption, is left unstated. Some sources accept this subject-object construct.

Geology makes ''to subduct'' into an [[intransitive verb]] and a [[reflexive verb]]. The lower plate itself is the subject. It subducts, in the sense of retreat, or removes itself, and while doing so, is the "subducting plate". Moreover, the word [[Slab (geology)|slab]] is specifically attached to the "subducting plate", even though in English the upper plate is just as much of a slab.<ref>{{cite web | title=Subduction Zone | website=Database of Individual Seismogenic Sources (DISS) | publisher=National Institute of Geophysics and Volcanology (INGV) | url=http://diss.rm.ingv.it/diss/index.php/help/58-definition-of-subduction-source | access-date=4 January 2021 | archive-date=23 April 2021 | archive-url=https://web.archive.org/web/20210423151754/http://diss.rm.ingv.it/diss/index.php/help/58-definition-of-subduction-source | url-status=dead }}</ref> The upper plate is left hanging, so to speak. To express it geology must switch to a different verb, typically ''to override''. The upper plate, the subject, performs the action of overriding the object, the lower plate, which is overridden.<ref>{{cite journal | last=Schultz | first=C. | year=2015 | title=Overriding plate's properties affect subduction | journal=Eos | volume=96 | doi=10.1029/2015EO026911 | url=https://eos.org/research-spotlights/overriding-plates-properties-affect-subduction-2#:~:text=Excepting%20the%20rare%20cases%20where,the%20mix%E2%80%94the%20overriding%20plate| doi-access=free }}</ref>