Editing Abyssal plain (section)

==Discovery==
{{See also|Bathymetry}}
[[File:Marianatrenchmap.png|thumb|right|Location of the [[Challenger Deep]] in the [[Mariana Trench]]]]

The landmark scientific [[Challenger expedition|expedition]] (December 1872 – May 1876) of the British [[Royal Navy]] survey ship [[HMS Challenger (1858)|HMS ''Challenger'']] yielded a tremendous amount of [[Bathymetry|bathymetric]] data, much of which has been confirmed by subsequent researchers. Bathymetric data obtained during the course of the Challenger expedition enabled scientists to draw maps,<ref name=Murray1891>{{Cite book
|author1=John Murray |author2=A.F. Renard |title=Report of the scientific results of the voyage of H.M.S. Challenger during the years 1873 to 1876
|publisher=Her Majesty's Stationery Office
|location=London
|year=1891
|url=http://www.19thcenturyscience.org/HMSC/HMSC-Reports/map-800/b-200.jpg
|access-date=26 June 2010}}{{page needed|date=December 2013}}</ref> which provided a rough outline of certain major submarine terrain features, such as the edge of the [[continental shelves]] and the [[Mid-Atlantic Ridge]]. This discontinuous set of data points was obtained by the simple technique of taking [[Sounding line|soundings]] by lowering long lines from the ship to the seabed.<ref name=Murray_Deepsea>{{Cite book
 |author1      = John Murray
 |author2      = A.F. Renard
 |title        = Report on the Deepsea Deposits based on the Specimens Collected during the Voyage of H.M.S. Challenger in the years 1873 to 1876
 |publisher    = Her Majesty's Stationery Office
 |location     = London
 |year         = 1891
 |url          = http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1891-DeepSeaDeposits/htm/doc.html
 |access-date   = 26 June 2010
 |archive-url  = https://web.archive.org/web/20110724205544/http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1891-DeepSeaDeposits/htm/doc.html
 |archive-date = 24 July 2011
 |url-status     = dead
}}{{page needed|date=December 2013}}</ref>

The Challenger expedition was followed by the 1879–1881 expedition of the [[USS Jeannette (1878)|''Jeannette'']], led by [[United States Navy]] Lieutenant [[George Washington DeLong]]. The team sailed across the [[Chukchi Sea]] and recorded [[meteorological]] and [[astronomical]] data in addition to taking soundings of the seabed. The ship became trapped in the [[Sea ice|ice pack]] near [[Wrangel Island]] in September 1879, and was ultimately crushed and sunk in June 1881.<ref>{{Cite book
 |author=Naval Historical Center 
 |title=Dictionary of American Naval Fighting Ships, Volume 3, G-K 
 |editor=James L. Mooney 
 |chapter=''Jeannette'' 
 |publisher=Defense Department, [[United States Department of the Navy|Department of the Navy]], Naval History Division 
 |location=Washington DC 
 |date=1977 
 |orig-year=First published in 1968 
 |isbn=978-0-16-002019-3 
 |oclc=2794587 
 |chapter-url=http://www.history.navy.mil/danfs/j2/jeannette.htm 
 |access-date=26 June 2010 
 |author-link=Naval History & Heritage Command 
 |archive-url=https://web.archive.org/web/20100708095936/http://www.history.navy.mil/danfs/j2/jeannette.htm 
 |archive-date=8 July 2010 
 |url-status=dead 
}}</ref>

The ''Jeannette'' expedition was followed by the 1893–1896 Arctic [[Nansen's Fram expedition|expedition]] of [[Norwegians|Norwegian]] explorer [[Fridtjof Nansen]] aboard the ''[[Fram (ship)|Fram]]'', which proved that the [[Arctic Ocean]] was a deep oceanic basin, uninterrupted by any significant land masses north of the [[Eurasia]]n continent.<ref name=Aber2006>{{Cite web
|author=James S. Aber
|title=History of Geology: Fridtjof Nansen
|url=http://academic.emporia.edu/aberjame/histgeol/nansen/nansen.htm
|publisher=[[Emporia State University]]
|location=[[Emporia, Kansas]]
|year=2006
|access-date=26 June 2010
|archive-url=https://web.archive.org/web/20090416163515/http://academic.emporia.edu/aberjame/histgeol/nansen/nansen.htm
|archive-date=16 April 2009
|url-status=dead
}}</ref>
<ref name=Krishfield>{{Cite web
|last=Krishfield|first=Rick
|title=Nansen and the Drift of the Fram (1893–1896)
|url=http://www.whoi.edu/beaufortgyre/history/history_fram.html|publisher= [[Woods Hole Oceanographic Institution]]
|work=Beaufort Gyre Exploration Project
|access-date=26 June 2010}}</ref>

Beginning in 1916, Canadian physicist [[Robert William Boyle]] and other scientists of the Anti-Submarine Detection Investigation Committee ([[ASDIC]]) undertook research which ultimately led to the development of [[sonar]] technology. [[Echo sounding|Acoustic sounding]] equipment was developed which could be operated much more rapidly than the sounding lines, thus enabling the [[German Meteor expedition]] aboard the German research vessel [[Meteor (1915)|Meteor]] (1925–27) to take frequent soundings on east-west Atlantic transects. Maps produced from these techniques show the major Atlantic basins, but the depth precision of these early instruments was not sufficient to reveal the flat featureless abyssal plains.<ref name=Maurer1933>{{Cite journal
|author1=Hans Maurer |author2=Theodor Stocks |title=Die Echolotengen des 'Meteor' Deutschen Atlantischen Exped. Meteor, 1925–1927
|journal=Wissenschaftliche Ergebnisse
|volume=2
|pages=458–460
|date=May–June 1933
|issue=5
|jstor=1786634}}</ref><ref name=Stocks1935>{{Cite journal
|author1=Theodor Stocks |author2=Georg Wust |title=Die Tiefenverhaltnisse des offenen Atlantischen Ozeans: Deutsche Atlantischen Exped. Meteor, 1925–1927
|journal=Wissenschaftliche Ergebnisse
|volume=3
|pages=1–31
|year=1935
|url=http://www.photolib.noaa.gov/htmls/map00085.htm
|access-date=26 June 2010}}</ref>

As technology improved, measurement of depth, [[latitude]] and [[longitude]] became more precise and it became possible to collect more or less continuous sets of data points. This allowed researchers to draw accurate and detailed maps of large areas of the ocean floor. Use of a continuously recording [[Fishfinder|fathometer]] enabled Tolstoy & Ewing in the summer of 1947 to identify and describe the first abyssal plain. This plain, south of [[Newfoundland and Labrador|Newfoundland]], is now known as the [[Sohm Abyssal Plain]].<ref name=Tolstoy1949>{{Cite journal
|author1=Ivan Tolstoy |author2=Maurice Ewing |title=North Atlantic hydrography and the mid-Atlantic Ridge
|journal=Geological Society of America Bulletin
|volume=60
|issue=10
|pages=1527–40
|date = October 1949
|doi=10.1130/0016-7606(1949)60[1527:NAHATM]2.0.CO;2
|issn=0016-7606
|bibcode = 1949GSAB...60.1527T }}</ref> Following this discovery many other examples were found in all the oceans.<ref name=Heezen1951>{{Cite journal
|author1=Bruce C. Heezen |author2=Maurice Ewing |author3=D.B. Ericson |title=Submarine topography in the North Atlantic
|journal=Geological Society of America Bulletin
|volume=62
|issue=12
|pages=1407–1417
|date=December 1951
|doi=10.1130/0016-7606(1951)62[1407:STITNA]2.0.CO;2
|issn=0016-7606
|bibcode = 1951GSAB...62.1407H }}</ref><ref name=Heezen1954>{{Cite journal
|author1=Bruce C. Heezen |author2=D.B. Ericson |author3=Maurice Ewing |title=Further evidence for a turbidity current following the 1929 Grand banks earthquake
|journal=Deep-Sea Research
|volume=1
|issue=4
|pages=193–202
|date = July 1954
|doi=10.1016/0146-6313(54)90001-5
|bibcode = 1954DSR.....1..193H }}</ref><ref name=Koczy1954>{{Cite journal
|author=F.F. Koczy
|title=A survey on deep-sea features taken during the Swedish deep-sea expedition
|journal=Deep-Sea Research
|volume=1
|issue=3
|pages=176–184
|year=1954
|doi=10.1016/0146-6313(54)90047-7
|bibcode = 1954DSR.....1..176K }}</ref><ref name=Heezen1962>{{Cite book
|author1=Bruce C. Heezen |title=Heezen, Bruce C., Marie Tharp, and Maurice Ewing: The Floors of the Oceans. I. The North Atlantic. Text to Accompany the Physiographic Diagram of the North Atlantic. With 49 fig., 30 plates. – New York, N.Y.: The Geological Society of America, Special Paper 65, 1959. 122 p. $10.00 |journal=Internationale Revue der Gesamten Hydrobiologie und Hydrographie |author2=Marie Tharp |author3=Maurice Ewing |chapter=The Floors of the Oceans. I. The North Atlantic. Text to Accompany the Physiographic Diagram of the North Atlantic
|editor=H. Caspers
|publisher=WILEY-VCH Verlag GmbH & Company
|location=Weinheim
|volume=47
|issue=3
|pages=487
|year=1962
|doi=10.1002/iroh.19620470311}}</ref><ref name=Heezen1963>{{Cite book
|author1=Bruce C. Heezen |author2=A.S. Laughton |title=The Sea
|chapter=Abyssal plains
|editor=M.N. Hill
|publisher=Wiley-Interscience
|location=New York
|volume=3
|pages=312–64
|year=1963}}</ref>

The [[Challenger Deep]] is the deepest surveyed point of all of Earth's oceans; it is at the south end of the [[Mariana Trench]] near the [[Mariana Islands]] group. The depression is named after HMS ''Challenger'', whose researchers made the first recordings of its depth on 23 March 1875 at [https://web.archive.org/web/20110310200116/http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1895-Summary/htm/doc878.html station 225]. The reported depth was 4,475 [[fathom]]s (8184&nbsp;meters) based on two separate soundings. On 1 June 2009, sonar mapping of the Challenger Deep by the [[Simrad Optronics|Simrad]] EM120 [[Multibeam echosounder|multibeam sonar bathymetry]] system aboard the [[RV Kilo Moana (T-AGOR-26)|R/V ''Kilo Moana'']] indicated a maximum depth of 10971&nbsp;meters (6.82 miles). The sonar system uses [[Phase (waves)|phase]] and [[amplitude]] bottom detection, with an accuracy of better than 0.2% of water depth (this is an error of about 22&nbsp;meters at this depth).<ref name=Moana1>{{Cite web
 |author=University of Hawaii Marine Center 
 |date=4 June 2009 
 |url=http://www.soest.hawaii.edu/UMC/Reports/Archives/KMreportJuneJuly2009.html 
 |title=Daily Reports for R/V KILO MOANA June & July 2009 
 |publisher=University of Hawaii 
 |location=Honolulu, Hawaii 
 |access-date=26 June 2010 
 |url-status=dead 
 |archive-url=https://archive.today/20120524194643/http://www.soest.hawaii.edu/UMC/Reports/Archives/KMreportJuneJuly2009.html 
 |archive-date=24 May 2012 
}}</ref><ref name=Moana2>{{Cite web
 |author=University of Hawaii Marine Center 
 |date=4 June 2009 
 |url=http://www.soest.hawaii.edu/UMC/KM/scienceequipment.htm 
 |title=Inventory of Scientific Equipment aboard the R/V KILO MOANA 
 |publisher=University of Hawaii 
 |location=Honolulu, Hawaii 
 |access-date=26 June 2010 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20100613143513/http://www.soest.hawaii.edu/UMC/KM/scienceequipment.htm 
 |archive-date=13 June 2010 
}}</ref>