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Coordinates: 71°00′S 70°00′W / 71.000°S 70.000°W / -71.000; -70.000
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{{Short description|Island in the Bellingshausen Sea off Antarctica}}
{{Short description|Island in the Bellingshausen Sea off Antarctica}}
{{other uses}}
{{other uses}}
{{Use dmy dates|date=April 2022}}
{{Infobox islands
{{Infobox islands
| name = Alexander Island
| name = Alexander Island
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| country = None
| country = None
| treaty_system = [[Antarctic Treaty System]]
| treaty_system = [[Antarctic Treaty System]]
}}
|local_name=Q'wanjob' Alexander}}


'''Alexander Island''', which is also known as '''Alexander I Island''', '''Alexander I Land''', '''Alexander Land''', '''Alexander I Archipelago''', and '''Zemlja Alexandra I''', is the largest island of [[Antarctica]]. It lies in the [[Bellingshausen Sea]] west of [[Palmer Land]], [[Antarctic Peninsula]] from which it is separated by [[Marguerite Bay]] and [[George VI Sound]]. [[George VI Ice Shelf]] entirely fills George VI Sound and connects Alexander Island to Palmer Land. The island partly surrounds [[Wilkins Sound]], which lies to its west.<ref name="Stewart2011a">Stewart, J. (2011) ''Antarctic An Encyclopedia'' McFarland & Company Inc, New York. 1776 pp. {{ISBN|9780786435906}}.</ref> Alexander Island is about {{convert|240|mi|km|order=flip}} long in a north–south direction, {{convert|50|mi|km|order=flip}} wide in the north, and {{convert|150|mi|km|order=flip}} wide in the south.<ref name=gnis>{{gnis|id=236|type=antarid}}</ref> Alexander Island is the second largest uninhabited island in the world, after [[Devon Island]].
'''Alexander Island''', which is also known as '''Alexander I Island''', '''Alexander I Land''', '''Alexander Land''', '''Alexander I Archipelago''', and '''Zemlja Alexandra I''', is the largest island of [[Antarctica]]. It lies in the [[Bellingshausen Sea]] west of [[Palmer Land]], [[Antarctic Peninsula]] from which it is separated by [[Marguerite Bay]] and [[George VI Sound]]. The [[George VI Ice Shelf]] entirely fills George VI Sound and connects Alexander Island to Palmer Land. The island partly surrounds [[Wilkins Sound]], which lies to its west.<ref name="Stewart2011a">Stewart, J. (2011) ''Antarctic An Encyclopedia'' McFarland & Company Inc, New York. 1776 pp. {{ISBN|9780786435906}}.</ref> Alexander Island is about {{convert|240|mi|km|order=flip}} long in a north–south direction, {{convert|50|mi|km|order=flip}} wide in the north, and {{convert|150|mi|km|order=flip}} wide in the south.<ref name=gnis>{{gnis|id=236|type=antarid}}</ref> Alexander Island is the second-largest uninhabited island in the world, after [[Devon Island]].


==History==
==History==
Alexander Island was discovered on January 28, 1821, by a [[Russia]]n expedition under [[Fabian Gottlieb von Bellingshausen]], who named it Alexander I Land for the reigning [[Tsar]] [[Alexander I of Russia]].
Alexander Island was discovered on January 28, 1821, by a Russian expedition under [[Fabian Gottlieb von Bellingshausen]], who named it Alexander I Land for the reigning [[Tsar]] [[Alexander I of Russia]].


What in fact is an island, was believed to be part of the Antarctic mainland until 1940. Its insular nature was proven in December 1940, by a two-person [[sledge]] party composed of [[Finn Ronne]] and [[Carl R. Eklund|Carl Eklund]] of the [[United States Antarctic Service]].<ref name=gnis/><ref>{{cite journal
What, in fact, is an island, was believed to be part of the Antarctic mainland until 1940. Its insular nature was proven in December 1940, by a two-person [[sledge]] party composed of [[Finn Ronne]] and [[Carl R. Eklund|Carl Eklund]] of the [[United States Antarctic Service]].<ref name=gnis/><ref>{{cite journal
| last=Siple |first=Paul
| last=Siple |first=Paul
| title=Obituary: Carl R. Eklund, 1909–1962
| title=Obituary: Carl R. Eklund, 1909–1962
Line 42: Line 43:
| publisher=Arctic Institute of North America
| publisher=Arctic Institute of North America
| access-date = 2013-01-19
| access-date = 2013-01-19
| doi=10.14430/arctic3531}}</ref> In the 1950s, a [[United Kingdom|British]] base administered as part of the [[British Antarctic Territory]] was constructed as [[Fossil Bluff]] (''Base KG'').<ref>[https://web.archive.org/web/20130707014400/http://www.antarctica.ac.uk/about_bas/our_organisation/eid/archives_met_list.pdf HANDLIST OF METEOROLOGY RECORDS FROM BRITISH ANTARCTIC RESEARCH STATIONS]. British Antarctic Survey Archives Service (2010)</ref>
| doi=10.14430/arctic3531}}</ref> In the 1950s, a British base administered as part of the [[British Antarctic Territory]] was constructed as [[Fossil Bluff]] (''Base KG'').<ref>[https://web.archive.org/web/20130707014400/http://www.antarctica.ac.uk/about_bas/our_organisation/eid/archives_met_list.pdf HANDLIST OF METEOROLOGY RECORDS FROM BRITISH ANTARCTIC RESEARCH STATIONS]. British Antarctic Survey Archives Service (2010)</ref>


The island was claimed by the [[United Kingdom]] in 1908 as part of the [[British Antarctic Territory]]. Territorial claims have also been set by both [[Chile]] (in 1940) and [[Argentina]] (in 1942).<ref>{{cite encyclopedia |encyclopedia=[[Encyclopædia Britannica]] |title=Alexander Island |url=http://www.britannica.com/EBchecked/topic/14177/Alexander-Island |access-date=20 January 2015 |date=20 July 1998}}</ref> Currently, under the [[Antarctic Treaty System|Antarctic Treaty]] no claim has been officially recognized. The island contains the British [[Fossil Bluff]] [[meteorology|meteorological]] centre and refuelling base.<ref>{{cite book|last1=Mills|first1=William|title=Exploring Polar Frontiers: A Historical Encyclopedia|date=2003|isbn=1-57607-422-6|pages=9|edition=1|url=https://books.google.com/books?id=PYdBH4dOOM4C&q=Fossil+Bluff+base&pg=PA9|access-date=20 January 2015}}</ref>
The island was claimed by the United Kingdom in 1908 as part of the [[British Antarctic Territory]]. Territorial claims have also been set by both [[Chile]] (in 1940) and [[Argentina]] (in 1942).<ref>{{cite encyclopedia |encyclopedia=[[Encyclopædia Britannica]] |title=Alexander Island |url=http://www.britannica.com/EBchecked/topic/14177/Alexander-Island |access-date=20 January 2015 |date=20 July 1998}}</ref> Currently, under the [[Antarctic Treaty System|Antarctic Treaty]] no claim has been officially recognized. The island contains the British [[Fossil Bluff]] [[meteorology|meteorological]] centre and refuelling base.<ref>{{cite book|last1=Mills|first1=William|title=Exploring Polar Frontiers: A Historical Encyclopedia|date=2003|isbn=1-57607-422-6|pages=9|edition=1|url=https://books.google.com/books?id=PYdBH4dOOM4C&q=Fossil+Bluff+base&pg=PA9|access-date=20 January 2015}}</ref>


==Geography==
==Geography==

[[File:Alexander-Island.jpg|thumb|left|Satellite photo of Alexander Island ([[NASA]] imagery)]]
[[File:Alexander-Island.jpg|thumb|left|Satellite photo of Alexander Island ([[NASA]] imagery)]]
[[File:Rocky mountain face, Alexander Island (6280674894).jpg|thumb|Alexander Island Mountain Ranges]]
[[File:Rocky mountain face, Alexander Island (6280674894).jpg|thumb|Alexander Island Mountain Ranges]]
The surface of Alexander Island is predominantly ice-covered. There exist some exposed [[nunatak]]s and a few ice-free areas of significant size, including Ablation Point Massif. The nunataks are the peaks of north–south trending mountain ranges and hills. They include the [[Colbert Mountains|Colbert]], [[Havre Mountains|Havre]], [[Lassus Mountains|Lassus]], [[Rouen Mountains|Rouen]], [[Sofia University Mountains|Sofia University]], [[Walton Mountains|Walton mountains]], the [[Staccato Peaks]], the [[Lully Foothills]], the [[Finlandia Foothills]], the [[Elgar Uplands]], and the [[Douglas Range]]. These mountains, peaks, hills, and uplands are surrounded by a permanent ice sheet, which consists of glaciers that flow off of Alexander Island. These glaciers flow west into the [[Bach Ice Shelf|Bach]] and [[Wilkins Sound|Wilkins Ice Shelves]] and Bellingshausen Sea, and east into the George VI Ice Shelf. The George VI Ice Shelf is fed by both by outlet glaciers from the ice cap on Palmer Land and Alexander Island.<ref name="Stewart2011a"/><ref name=gnis/><ref name="Smith2007a">{{cite journal|doi=10.1017/S0954102007000193|title=George VI Ice Shelf: Past history, present behaviour and potential mechanisms for future collapse|year=2007|last1=Smith|first1=James A.|last2=Bentley|first2=Michael J.|last3=Hodgson|first3=Dominic A.|last4=Cook|first4=Alison J.|journal=Antarctic Science|volume=19|issue=1|pages=131–142|bibcode=2007AntSc..19..131S|s2cid=128840101}}</ref>
The surface of Alexander Island is predominantly ice-covered. There exist some exposed [[nunatak]]s and a few ice-free areas of significant size, including Ablation Point Massif. The nunataks are the peaks of north–south trending mountain ranges and hills. They include the [[Colbert Mountains|Colbert]], [[Havre Mountains|Havre]], [[Lassus Mountains|Lassus]], [[Rouen Mountains|Rouen]], [[Sofia University Mountains|Sofia University]], and [[Walton Mountains]], the [[Staccato Peaks]], the [[Lully Foothills]], the [[Finlandia Foothills]], the [[Elgar Uplands]], and the [[Douglas Range]]. These mountains, peaks, hills, and uplands are surrounded by a permanent ice sheet, which consists of glaciers that flow off of Alexander Island. These glaciers flow west into the [[Bach Ice Shelf|Bach]] and [[Wilkins Sound|Wilkins Ice Shelves]] and Bellingshausen Sea, and east into the George VI Ice Shelf. The George VI Ice Shelf is fed by both by [[Outlet glacier|outlet glaciers]] from the ice cap on Palmer Land and Alexander Island.<ref name="Stewart2011a"/><ref name=gnis/><ref name="Smith2007a">{{cite journal|doi=10.1017/S0954102007000193|title=George VI Ice Shelf: Past history, present behaviour and potential mechanisms for future collapse|year=2007|last1=Smith|first1=James A.|last2=Bentley|first2=Michael J.|last3=Hodgson|first3=Dominic A.|last4=Cook|first4=Alison J.|journal=Antarctic Science|volume=19|issue=1|pages=131–142|bibcode=2007AntSc..19..131S|s2cid=128840101}}</ref>


Another notable feature of Alexander Island is [[Hodgson Lake]]. Hodgson Lake is a former subglacial lake that has emerged from under an ice sheet that had covered it. Hodgson Lake is {{convert|2|km|mi|abbr=on}} long by {{convert|1.5|km|mi|abbr=on}}, and has a {{convert|93.4|m|ft|abbr=on}} deep water column that lies sealed beneath a {{convert|3.6|to|4.0|m|ft|abbr=on}} thick perennial lake ice.
Another notable feature of Alexander Island is [[Hodgson Lake]], a former [[subglacial lake]] that has emerged from under an ice sheet that had covered it. Hodgson Lake is {{convert|2|km|mi|abbr=on}} long by {{convert|1.5|km|mi|abbr=on}}, and has a {{convert|93.4|m|ft|abbr=on}} deep [[water column]] that lies sealed beneath a {{convert|3.6|to|4.0|m|ft|abbr=on}} thick perennial lake ice.


The northern side of Hodgson Lake is bounded by the [[Saturn Glacier]], which flows east into George VI Sound, while the southern side of Hodgson Lake is bounded by the northern face of [[Citadel Bastion]]. During the [[Last Glacial Maximum]], Hodgson Lake was covered by the ice sheet at least {{convert|470|m|ft|abbr=on}} thick.
The northern side of Hodgson Lake is bounded by the [[Saturn Glacier]], which flows east into George VI Sound, while the southern side of Hodgson Lake is bounded by the northern face of [[Citadel Bastion]]. During the [[Last Glacial Maximum]], Hodgson Lake was covered by the ice sheet at least {{convert|470|m|ft|abbr=on}} thick.


This ice sheet started thinning about 13,500 years ago. It retreated and left Hodgson Lake covered by perennial ice sometime before 11,000 years ago. This lake has been covered by perennial ice since that time.<ref name=" HodgsonOthers2009a">{{cite journal|doi=10.1016/j.quascirev.2009.04.011|title=Exploring former subglacial Hodgson Lake, Antarctica Paper I: Site description, geomorphology and limnology|year=2009|last1=Hodgson|first1=Dominic A.|last2=Roberts|first2=Stephen J.|last3=Bentley|first3=Michael J.|last4=Smith|first4=James A.|last5=Johnson|first5=Joanne S.|last6=Verleyen|first6=Elie|last7=Vyverman|first7=Wim|last8=Hodson|first8=Andy J.|last9=Leng|first9=Melanie J.|last10=Cziferszky|first10=Andreas|last11=Fox|first11=Adrian J.|last12=Sanderson|first12=David C.W.|journal=Quaternary Science Reviews|volume=28|issue=23–24|pages=2295–2309|bibcode=2009QSRv...28.2295H}}</ref><ref name=" HodgsonOthers2009b">{{cite journal|doi=10.1016/j.quascirev.2009.04.014|title=Exploring former subglacial Hodgson Lake, Antarctica. Paper II: Palaeolimnology|year=2009|last1=Hodgson|first1=Dominic A.|last2=Roberts|first2=Stephen J.|last3=Bentley|first3=Michael J.|last4=Carmichael|first4=Emma L.|last5=Smith|first5=James A.|last6=Verleyen|first6=Elie|last7=Vyverman|first7=Wim|last8=Geissler|first8=Paul|last9=Leng|first9=Melanie J.|last10=Sanderson|first10=David C.W.|journal=Quaternary Science Reviews|volume=28|issue=23–24|pages=2310–2325|bibcode=2009QSRv...28.2310H}}</ref>
This ice sheet started thinning about 13,500 years ago. It retreated and left Hodgson Lake covered by perennial ice sometime before 11,000 years ago. This lake has been covered by perennial ice since that time.<ref name=" HodgsonOthers2009a">{{cite journal|doi=10.1016/j.quascirev.2009.04.011|title=Exploring former subglacial Hodgson Lake, Antarctica Paper I: Site description, geomorphology and limnology|year=2009|last1=Hodgson|first1=Dominic A.|last2=Roberts|first2=Stephen J.|last3=Bentley|first3=Michael J.|last4=Smith|first4=James A.|last5=Johnson|first5=Joanne S.|last6=Verleyen|first6=Elie|last7=Vyverman|first7=Wim|last8=Hodson|first8=Andy J.|last9=Leng|first9=Melanie J.|last10=Cziferszky|first10=Andreas|last11=Fox|first11=Adrian J.|last12=Sanderson|first12=David C.W.|journal=Quaternary Science Reviews|volume=28|issue=23–24|pages=2295–2309|bibcode=2009QSRv...28.2295H}}</ref><ref name=" HodgsonOthers2009b">{{cite journal|doi=10.1016/j.quascirev.2009.04.014|title=Exploring former subglacial Hodgson Lake, Antarctica. Paper II: Palaeolimnology|year=2009|last1=Hodgson|first1=Dominic A.|last2=Roberts|first2=Stephen J.|last3=Bentley|first3=Michael J.|last4=Carmichael|first4=Emma L.|last5=Smith|first5=James A.|last6=Verleyen|first6=Elie|last7=Vyverman|first7=Wim|last8=Geissler|first8=Paul|last9=Leng|first9=Melanie J.|last10=Sanderson|first10=David C.W.|journal=Quaternary Science Reviews|volume=28|issue=23–24|pages=2310–2325|bibcode=2009QSRv...28.2310H}}</ref>
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===Brahms Inlet===
===Brahms Inlet===
'''Brahms Inlet''' ({{Coord|71|28|S|73|41|W|source:GNIS|display=inline}}) is an ice-filled inlet, {{convert|25|nmi|km}} long and {{convert|6|nmi|km}} wide, indenting the north side of [[Beethoven Peninsula]] on Alexander Island between [[Harris Peninsula]] and [[Derocher Peninsula]], while the headland [[Mazza Point]] lies immediately northeast of the inlet and [[Mount Grieg]] lies immediately southeast of the base of Brahms Inlet. It was observed from the air and first mapped by the [[Ronne Antarctic Research Expedition]] (RARE), 1947–48, and re-mapped from the RARE air photos by [[Derek J.H. Searle]] of the [[Falkland Islands Dependencies Survey]] in 1960. It was named by the [[UK Antarctic Place-Names Committee]] after [[Johannes Brahms]], the German composer.<ref>{{cite gnis | type = antarid | id = 1820| name = Brahms Inlet| access-date = 2011-08-15}}</ref>
'''Brahms Inlet''' ({{Coord|71|28|S|73|41|W|source:GNIS|display=inline}}) is an ice-filled [[inlet]], {{convert|25|nmi|km}} long and {{convert|6|nmi|km}} wide, indenting the north side of [[Beethoven Peninsula]] on Alexander Island between [[Harris Peninsula]] and [[Derocher Peninsula]], while the headland [[Mazza Point]] lies immediately northeast of the inlet and [[Mount Grieg]] lies immediately southeast of the base of Brahms Inlet. It was observed from the air and first mapped by the [[Ronne Antarctic Research Expedition]] (RARE), 1947–48, and re-mapped from the RARE air photos by [[Derek J.H. Searle]] of the [[Falkland Islands Dependencies Survey]] in 1960. It was named by the [[UK Antarctic Place-Names Committee]] after [[Johannes Brahms]], the German composer.<ref>{{cite gnis | type = antarid | id = 1820| name = Brahms Inlet| access-date = 2011-08-15}}</ref>


===Harris Peninsula===
===Harris Peninsula===
'''Harris Peninsula''' ({{coord|71|31|S|74|6|W|source:GNIS|display=inline}}) is a broad snow-covered [[peninsula]] surmounted by [[Mount Lee (Antarctica)|Mount Lee]], between [[Verdi Inlet]] and [[Brahms Inlet]] on the north side of the [[Beethoven Peninsula]], located in the southwest portion of Alexander Island, [[Antarctica]]. It is one of eight peninsulas of Alexander Island. It was photographed from the air by the [[Ronne Antarctic Research Expedition]], 1947–48, and mapped from these photographs by [[D. Searle]] of the [[Falkland Islands Dependencies Survey]], 1960. It was named by the [[Advisory Committee on Antarctic Names]] for Commander [[Michael J. Harris]], [[U.S. Navy]], [[Commanding Officer]] of Squadron [[VXE-6]], from May 1982 to May 1983.<ref>{{cite gnis | type = antarid | id = 6422| name = Harris Peninsula | access-date = 2012-05-24}}</ref>
'''Harris Peninsula''' ({{coord|71|31|S|74|6|W|source:GNIS|display=inline}}) is a broad snow-covered [[peninsula]] surmounted by [[Mount Lee (Antarctica)|Mount Lee]], between [[Verdi Inlet]] and [[Brahms Inlet]] on the north side of the [[Beethoven Peninsula]], located in the southwest portion of Alexander Island, [[Antarctica]]. It is one of eight peninsulas of Alexander Island. It was photographed from the air by the RARE, 1947–48, and mapped from these photographs by [[D. Searle]] of the [[Falkland Islands Dependencies Survey]], 1960. It was named by the [[Advisory Committee on Antarctic Names]] for Commander [[Michael J. Harris]], [[U.S. Navy]], [[Commanding Officer]] of Squadron [[VXE-6]], from May 1982 to May 1983.<ref>{{cite gnis | type = antarid | id = 6422| name = Harris Peninsula | access-date = 2012-05-24}}</ref>


===Lyadov Glacier===
===Lyadov Glacier===
'''Lyadov Glacier''' ({{coord|71|32|00|S|73|45|00|W|display=inline}}) is a glacier flowing east-northeast from [[Harris Peninsula]], Alexander Island, into [[Brahms Inlet]]. It was named by the [[USSR Academy of Sciences]] in 1987 after [[Anatoly Lyadov]] (1855–1914), a Russian composer.
'''Lyadov Glacier''' ({{coord|71|32|00|S|73|45|00|W|display=inline}}) is a glacier flowing east-northeast from [[Harris Peninsula]], Alexander Island, into [[Brahms Inlet]]. It was named by the USSR Academy of Sciences in 1987 after [[Anatoly Lyadov]] (1855–1914), a Russian composer.


==Geology==
==Geology==
[[File:Antarctic Peninsula Cross Section.jpg|thumb|Antarctic Peninsula's [[Tectonics|tectonic]] movement]]
[[File:Antarctic Peninsula Cross Section.jpg|thumb|Antarctic Peninsula's [[Tectonics|tectonic]] movement]]
[[File:Kg hut new view.jpg|thumb|left|Fossil Bluff base on Alexander Island]]
[[File:Kg hut new view.jpg|thumb|left|Fossil Bluff base on Alexander Island]]
According to Hole, "The geology of Alexander Island can be attributed mainly to processes associated with the [[subduction]] of proto-Pacific [[oceanic crust]] along the western margin of the Antarctic Peninsula, from latest [[Triassic]] to [[Late Tertiary]] times." The LeMay Group [[accretionary prism]] complex, along with [[plutonic]] and [[volcanic]] rocks, are prevalent along the western portion of the island. The LeMay Group consists of variably-deformed and [[metamorphosed]] sedimentary and igneous rocks. Although it is dominated by deformed [[arkosic]] sedimentary rocks, it includes [[turbiditic]] [[greywackes]], black mudstones, and [[conglomerate (geology)|conglomerates]]. The 4&nbsp;km thick [[Upper Jurassic]] to [[Lower Cretaceous]] Fossil Bluff Group sedimentary rocks [[outcrop]] as a 250&nbsp;km long by 30&nbsp;km wide belt along the eastern coast. This Fossil Bluff Group consists of a basal deep-marine assemblage 2200 m thick, overlain by a [[mudstone]] assemblage up to 950 m thick, followed by a shallow-marine assemblage of coarsening upward [[sandstone]]s. [[Alkali basalt]]s erupted after the cessation of subduction. These range in age from the [[tephrite]]s at Mount Pinafore (5.5–7.6 Ma), to the [[basanite]]s at [[Rothschild Island]] (5.5 Ma) and Hornpipe Heights (2.5 Ma), to the alkali and [[olivine basalt]]s on [[Beethoven Peninsula]] (<1-2.5 Ma).<ref>{{cite book |last1=Hole |first1=M.J. |last2=Smellie |first2=J.L. |last3=Marriner |first3=G.F. |editor1-last=Thomson |editor1-first=M.R.A. |editor2-last=Crame |editor2-first=J.A. |editor3-last=Thomson |editor3-first=J.W. |title=Geochemistry and tectonic setting of Cenozoic alkalne basalts from Alexander Island, Antarctic Peninsula, in Geological Evolution of Antarctica |date=1991 |publisher=Cambridge University Press |location=Cambridge |isbn=9780521372664 |pages=521–522}}</ref><ref>{{cite book |last1=Butterworth |first1=P.J. |last2=Macdonald |first2=D.I.M. |editor1-last=Thomson |editor1-first=M.R.A. |editor2-last=Crame |editor2-first=J.A. |editor3-last=Thomson |editor3-first=J.W. |title=Basin shallowing from the Mesozoic Fossil Bluff Group of Alexander Island and its regional tectonic significance, in Geological Evolution of Antarctica |date=1991 |publisher=Cambridge University Press |location=Cambridge |isbn=9780521372664 |pages=449–453}}</ref><ref>{{cite book |last1=Tranter |first1=T.H. |editor1-last=Thomson |editor1-first=M.R.A. |editor2-last=Crame |editor2-first=J.A. |editor3-last=Thomson |editor3-first=J.W. |title=Accretion and subduction processes along the Pacific margin of Gondwana, central Alexander Island, in Geological Evolution of Antarctica |date=1991 |publisher=Cambridge University Press |location=Cambridge |isbn=9780521372664 |pages=437–441}}</ref><ref name=nell>{{cite book |last1=Nell |first1=P.A.R. |last2=Storey |first2=B.B. |editor1-last=Thomson |editor1-first=M.R.A. |editor2-last=Crame |editor2-first=J.A. |editor3-last=Thomson |editor3-first=J.W. |title=Strike-slip tectonics within the Antarctic Peninsula fore-arc, in Geological Evolution of Antarctica |date=1991 |publisher=Cambridge University Press |location=Cambridge |isbn=9780521372664 |pages=443–448}}</ref><ref name="MacdonaldOthers1990a">Macdonald, D.I.M. and P.J. Butterworth (1990) "The stratigraphy, setting and hydrocarbon potential of the Mesozoic sedimentary basins of the Antarctic Peninsula." in B. John, ed., pp. 101–125. ''Antarctica as an exploration frontier; hydrocarbon potential, geology, and hazards''. AAPG Studies in Geology. vol. 31 American Association of Petroleum Geologists, Tulsa, Oklahoma. {{doi|10.1306/St31524C8}}</ref><ref name="MacdonaldOthers1999a">{{cite journal|doi=10.1046/j.1365-3121.1999.00244.x|title=On the origin of fore-arc basins: New evidence of formation by rifting from the Jurassic of Alexander Island, Antarctica|year=1999|last1=MacDonald|last2=Leat|last3=Doubleday|last4=Kelly|journal=Terra Nova|volume=11|issue=4|pages=186–193|bibcode=1999TeNov..11..186M}}</ref><ref name="VaughanOthers1999a">{{cite journal|doi=10.1144/jgs.157.6.1243|title=The eastern Palmer Land shear zone: A new terrane accretion model for the Mesozoic development of the Antarctic Peninsula|year=2000|last1=Vaughan|first1=Alan P. M.|last2=Storey|first2=Bryan C.|journal=Journal of the Geological Society|volume=157|issue=6|pages=1243–1256|bibcode=2000JGSoc.157.1243V|s2cid=128496050}}</ref><ref name="McCarron Others1998a">{{cite journal|doi=10.1144/gsjgs.155.2.0269|title=Tectonic implications of fore-arc magmatism and generation of high-magnesian andesites: Alexander Island, Antarctica|year=1998|last1=McCarron|first1=J. J.|last2=Smellie|first2=J. L.|journal=Journal of the Geological Society|volume=155|issue=2|pages=269–280|bibcode=1998JGSoc.155..269M|s2cid=129620018}}</ref>
According to Hole, "The geology of Alexander Island can be attributed mainly to processes associated with the [[subduction]] of proto-Pacific [[oceanic crust]] along the western margin of the Antarctic Peninsula, from latest [[Triassic]] to [[Late Tertiary]] times." The LeMay Group [[accretionary prism]] complex, along with [[plutonic]] and [[volcanic]] rocks, are prevalent along the western portion of the island. The LeMay Group consists of variably-deformed and [[metamorphosed]] sedimentary and igneous rocks. Although it is dominated by deformed [[arkosic]] sedimentary rocks, it includes [[turbiditic]] [[greywackes]], black mudstones, and [[conglomerate (geology)|conglomerates]]. The {{Convert|4|km|mi|abbr=off|sp=us}} thick [[Upper Jurassic]] to [[Lower Cretaceous]] Fossil Bluff Group sedimentary rocks [[outcrop]] as a {{Convert|250|km|mi|abbr=off|sp=us}} long by {{Convert|30|km|mi|abbr=off|sp=us}} wide belt along the eastern coast. This Fossil Bluff Group consists of a basal deep-marine assemblage {{Convert|2200|m|ft|abbr=off|sp=us}} thick, overlain by a [[mudstone]] assemblage up to {{Convert|950|m|ft|abbr=off|sp=us}} thick, followed by a shallow-marine assemblage of coarsening upward [[sandstone]]s. [[Alkali basalt]]s erupted after the cessation of subduction. These range in age from the [[tephrite]]s at Mount Pinafore (5.5–7.6 Ma), to the [[basanite]]s at [[Rothschild Island]] (5.5 Ma) and Hornpipe Heights (2.5 Ma), to the alkali and [[olivine basalt]]s on [[Beethoven Peninsula]] (<1-2.5 Ma).<ref>{{cite book |last1=Hole |first1=M.J. |last2=Smellie |first2=J.L. |last3=Marriner |first3=G.F. |editor1-last=Thomson |editor1-first=M.R.A. |editor2-last=Crame |editor2-first=J.A. |editor3-last=Thomson |editor3-first=J.W. |title=Geochemistry and tectonic setting of Cenozoic alkalne basalts from Alexander Island, Antarctic Peninsula, in Geological Evolution of Antarctica |date=1991 |publisher=Cambridge University Press |location=Cambridge |isbn=9780521372664 |pages=521–522}}</ref><ref>{{cite book |last1=Butterworth |first1=P.J. |last2=Macdonald |first2=D.I.M. |editor1-last=Thomson |editor1-first=M.R.A. |editor2-last=Crame |editor2-first=J.A. |editor3-last=Thomson |editor3-first=J.W. |title=Basin shallowing from the Mesozoic Fossil Bluff Group of Alexander Island and its regional tectonic significance, in Geological Evolution of Antarctica |date=1991 |publisher=Cambridge University Press |location=Cambridge |isbn=9780521372664 |pages=449–453}}</ref><ref>{{cite book |last1=Tranter |first1=T.H. |editor1-last=Thomson |editor1-first=M.R.A. |editor2-last=Crame |editor2-first=J.A. |editor3-last=Thomson |editor3-first=J.W. |title=Accretion and subduction processes along the Pacific margin of Gondwana, central Alexander Island, in Geological Evolution of Antarctica |date=1991 |publisher=Cambridge University Press |location=Cambridge |isbn=9780521372664 |pages=437–441}}</ref><ref name=nell>{{cite book |last1=Nell |first1=P.A.R. |last2=Storey |first2=B.B. |editor1-last=Thomson |editor1-first=M.R.A. |editor2-last=Crame |editor2-first=J.A. |editor3-last=Thomson |editor3-first=J.W. |title=Strike-slip tectonics within the Antarctic Peninsula fore-arc, in Geological Evolution of Antarctica |date=1991 |publisher=Cambridge University Press |location=Cambridge |isbn=9780521372664 |pages=443–448}}</ref><ref name="MacdonaldOthers1990a">Macdonald, D.I.M. and P.J. Butterworth (1990) "The stratigraphy, setting and hydrocarbon potential of the Mesozoic sedimentary basins of the Antarctic Peninsula." in B. John, ed., pp. 101–125. ''Antarctica as an exploration frontier; hydrocarbon potential, geology, and hazards''. AAPG Studies in Geology. vol. 31 American Association of Petroleum Geologists, Tulsa, Oklahoma. {{doi|10.1306/St31524C8}}</ref><ref name="MacdonaldOthers1999a">{{cite journal|doi=10.1046/j.1365-3121.1999.00244.x|title=On the origin of fore-arc basins: New evidence of formation by rifting from the Jurassic of Alexander Island, Antarctica|year=1999|last1=MacDonald|last2=Leat|last3=Doubleday|last4=Kelly|journal=Terra Nova|volume=11|issue=4|pages=186–193|bibcode=1999TeNov..11..186M|s2cid=128675340 }}</ref><ref name="VaughanOthers1999a">{{cite journal|doi=10.1144/jgs.157.6.1243|title=The eastern Palmer Land shear zone: A new terrane accretion model for the Mesozoic development of the Antarctic Peninsula|year=2000|last1=Vaughan|first1=Alan P. M.|last2=Storey|first2=Bryan C.|journal=Journal of the Geological Society|volume=157|issue=6|pages=1243–1256|bibcode=2000JGSoc.157.1243V|s2cid=128496050}}</ref><ref name="McCarron Others1998a">{{cite journal|doi=10.1144/gsjgs.155.2.0269|title=Tectonic implications of fore-arc magmatism and generation of high-magnesian andesites: Alexander Island, Antarctica|year=1998|last1=McCarron|first1=J. J.|last2=Smellie|first2=J. L.|journal=Journal of the Geological Society|volume=155|issue=2|pages=269–280|bibcode=1998JGSoc.155..269M|s2cid=129620018}}</ref>


The LeMay Range [[fault (geology)|Fault]] trends N-S, parallel to the [[George VI Sound]], and the Fossil Bluff Formation is downfaulted to the east of this fault against the LeMay Group. Sand dykes are found against this fault zone and in many other parts of the Fossil Bay Formation. Fossils within the Fossil Bluff Formation include [[ammonite]]s, [[belemnite]]s, [[bivalve]]s, and [[serpulid]]s.<ref name=nell/>
The LeMay Range [[fault (geology)|Fault]] trends N-S, parallel to the [[George VI Sound]], and the Fossil Bluff Formation is downfaulted to the east of this fault against the LeMay Group. Sand dykes are found against this fault zone and in many other parts of the Fossil Bay Formation. Fossils within the Fossil Bluff Formation include [[ammonite]]s, [[belemnite]]s, [[bivalve]]s, and [[serpulid]]s.<ref name=nell/>


== See also ==
==See also==
{{Div col|small=yes}}
{{Div col|small=yes}}
* [[Adelaide Island]]
* [[Adelaide Island]]
* [[Argentine Antarctica]]
* [[Argentine Antarctica]]
* [[British Antarctic Territory]]
* [[British Antarctic Territory]]
* [[Antártica|Chilean Antarctic Territory]]
* [[Chilean Antarctic Territory]]
* [[Composite Antarctic Gazetteer]]
* [[Composite Antarctic Gazetteer]]
* [[Geology of the Antarctic Peninsula]]
* [[Geology of the Antarctic Peninsula]]
* [[List of Antarctic and sub-Antarctic islands#List of Antarctic islands south of 60° S|List of Antarctic islands south of 60° S]]
* [[List of Antarctic and sub-Antarctic islands#List of Antarctic islands south of 60° S|List of Antarctic islands south of 60° S]]
* [[List of Bulgarian toponyms in Antarctica]]
* [[List of Bulgarian toponyms in Antarctica]]
* [[Peel Cirque]]
* [[Scarab Bluff]]
* [[Scientific Committee on Antarctic Research|SCAR]]
* [[Scientific Committee on Antarctic Research|SCAR]]
* [[Territorial claims in Antarctica]]
* [[Territorial claims in Antarctica]]
* [[Witt Bluff]]
{{Div col end}}
{{Div col end}}
{{Portal inline|Islands}}
{{Portal inline|Geography}}
{{Portal inline|Geography}}


==References==
==References==
{{reflist|30em}}
{{reflist}}
{{Commons category|Alexander Island}}
{{Commons category|Alexander Island}}


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{{Antarctica}}
{{Antarctica}}
{{World's largest islands}}
{{World's largest islands}}

{{Authority control}}
{{Authority control}}


Latest revision as of 12:11, 28 March 2024

For other uses, see Alexander Island (disambiguation).

Alexander Island
Alexander Island shown within Antarctica
Alexander Island is located in Antarctic Peninsula
Alexander Island
Alexander Island
Geography
LocationAntarctica
Coordinates71°00′S 70°00′W / 71.000°S 70.000°W / -71.000; -70.000
Area49,070 km2 (18,950 sq mi)
Area rank28th
Length390 km (242 mi)
Width80 km (50 mi)
Highest elevation2,987 m (9800 ft)
Highest pointMount Stephenson
Administration
Administered under the Antarctic Treaty System
Demographics
Population0

Alexander Island, which is also known as Alexander I Island, Alexander I Land, Alexander Land, Alexander I Archipelago, and Zemlja Alexandra I, is the largest island of Antarctica. It lies in the Bellingshausen Sea west of Palmer Land, Antarctic Peninsula from which it is separated by Marguerite Bay and George VI Sound. The George VI Ice Shelf entirely fills George VI Sound and connects Alexander Island to Palmer Land. The island partly surrounds Wilkins Sound, which lies to its west.[1] Alexander Island is about 390 kilometres (240 mi) long in a north–south direction, 80 kilometres (50 mi) wide in the north, and 240 kilometres (150 mi) wide in the south.[2] Alexander Island is the second-largest uninhabited island in the world, after Devon Island.

History

[edit]

Alexander Island was discovered on January 28, 1821, by a Russian expedition under Fabian Gottlieb von Bellingshausen, who named it Alexander I Land for the reigning Tsar Alexander I of Russia.

What, in fact, is an island, was believed to be part of the Antarctic mainland until 1940. Its insular nature was proven in December 1940, by a two-person sledge party composed of Finn Ronne and Carl Eklund of the United States Antarctic Service.[2][3] In the 1950s, a British base administered as part of the British Antarctic Territory was constructed as Fossil Bluff (Base KG).[4]

The island was claimed by the United Kingdom in 1908 as part of the British Antarctic Territory. Territorial claims have also been set by both Chile (in 1940) and Argentina (in 1942).[5] Currently, under the Antarctic Treaty no claim has been officially recognized. The island contains the British Fossil Bluff meteorological centre and refuelling base.[6]

Geography

[edit]
Satellite photo of Alexander Island (NASA imagery)
Alexander Island Mountain Ranges

The surface of Alexander Island is predominantly ice-covered. There exist some exposed nunataks and a few ice-free areas of significant size, including Ablation Point Massif. The nunataks are the peaks of north–south trending mountain ranges and hills. They include the Colbert, Havre, Lassus, Rouen, Sofia University, and Walton Mountains, the Staccato Peaks, the Lully Foothills, the Finlandia Foothills, the Elgar Uplands, and the Douglas Range. These mountains, peaks, hills, and uplands are surrounded by a permanent ice sheet, which consists of glaciers that flow off of Alexander Island. These glaciers flow west into the Bach and Wilkins Ice Shelves and Bellingshausen Sea, and east into the George VI Ice Shelf. The George VI Ice Shelf is fed by both by outlet glaciers from the ice cap on Palmer Land and Alexander Island.[1][2][7]

Another notable feature of Alexander Island is Hodgson Lake, a former subglacial lake that has emerged from under an ice sheet that had covered it. Hodgson Lake is 2 km (1.2 mi) long by 1.5 km (0.93 mi), and has a 93.4 m (306 ft) deep water column that lies sealed beneath a 3.6 to 4.0 m (11.8 to 13.1 ft) thick perennial lake ice.

The northern side of Hodgson Lake is bounded by the Saturn Glacier, which flows east into George VI Sound, while the southern side of Hodgson Lake is bounded by the northern face of Citadel Bastion. During the Last Glacial Maximum, Hodgson Lake was covered by the ice sheet at least 470 m (1,540 ft) thick.

This ice sheet started thinning about 13,500 years ago. It retreated and left Hodgson Lake covered by perennial ice sometime before 11,000 years ago. This lake has been covered by perennial ice since that time.[8][9]

Other features on the island include Damocles Point[10] and Mount Tyrrell.

Brahms Inlet

[edit]

Brahms Inlet (71°28′S 73°41′W / 71.467°S 73.683°W / -71.467; -73.683) is an ice-filled inlet, 25 nautical miles (46 km) long and 6 nautical miles (11 km) wide, indenting the north side of Beethoven Peninsula on Alexander Island between Harris Peninsula and Derocher Peninsula, while the headland Mazza Point lies immediately northeast of the inlet and Mount Grieg lies immediately southeast of the base of Brahms Inlet. It was observed from the air and first mapped by the Ronne Antarctic Research Expedition (RARE), 1947–48, and re-mapped from the RARE air photos by Derek J.H. Searle of the Falkland Islands Dependencies Survey in 1960. It was named by the UK Antarctic Place-Names Committee after Johannes Brahms, the German composer.[11]

Harris Peninsula

[edit]

Harris Peninsula (71°31′S 74°6′W / 71.517°S 74.100°W / -71.517; -74.100) is a broad snow-covered peninsula surmounted by Mount Lee, between Verdi Inlet and Brahms Inlet on the north side of the Beethoven Peninsula, located in the southwest portion of Alexander Island, Antarctica. It is one of eight peninsulas of Alexander Island. It was photographed from the air by the RARE, 1947–48, and mapped from these photographs by D. Searle of the Falkland Islands Dependencies Survey, 1960. It was named by the Advisory Committee on Antarctic Names for Commander Michael J. Harris, U.S. Navy, Commanding Officer of Squadron VXE-6, from May 1982 to May 1983.[12]

Lyadov Glacier

[edit]

Lyadov Glacier (71°32′00″S 73°45′00″W / 71.53333°S 73.75000°W / -71.53333; -73.75000) is a glacier flowing east-northeast from Harris Peninsula, Alexander Island, into Brahms Inlet. It was named by the USSR Academy of Sciences in 1987 after Anatoly Lyadov (1855–1914), a Russian composer.

Geology

[edit]
Antarctic Peninsula's tectonic movement
Fossil Bluff base on Alexander Island

According to Hole, "The geology of Alexander Island can be attributed mainly to processes associated with the subduction of proto-Pacific oceanic crust along the western margin of the Antarctic Peninsula, from latest Triassic to Late Tertiary times." The LeMay Group accretionary prism complex, along with plutonic and volcanic rocks, are prevalent along the western portion of the island. The LeMay Group consists of variably-deformed and metamorphosed sedimentary and igneous rocks. Although it is dominated by deformed arkosic sedimentary rocks, it includes turbiditic greywackes, black mudstones, and conglomerates. The 4 kilometers (2.5 miles) thick Upper Jurassic to Lower Cretaceous Fossil Bluff Group sedimentary rocks outcrop as a 250 kilometers (160 miles) long by 30 kilometers (19 miles) wide belt along the eastern coast. This Fossil Bluff Group consists of a basal deep-marine assemblage 2,200 meters (7,200 feet) thick, overlain by a mudstone assemblage up to 950 meters (3,120 feet) thick, followed by a shallow-marine assemblage of coarsening upward sandstones. Alkali basalts erupted after the cessation of subduction. These range in age from the tephrites at Mount Pinafore (5.5–7.6 Ma), to the basanites at Rothschild Island (5.5 Ma) and Hornpipe Heights (2.5 Ma), to the alkali and olivine basalts on Beethoven Peninsula (<1-2.5 Ma).[13][14][15][16][17][18][19][20]

The LeMay Range Fault trends N-S, parallel to the George VI Sound, and the Fossil Bluff Formation is downfaulted to the east of this fault against the LeMay Group. Sand dykes are found against this fault zone and in many other parts of the Fossil Bay Formation. Fossils within the Fossil Bluff Formation include ammonites, belemnites, bivalves, and serpulids.[16]

See also

[edit]

icon Islands portal icon Geography portal

References

[edit]
  1. ^ a b Stewart, J. (2011) Antarctic An Encyclopedia McFarland & Company Inc, New York. 1776 pp. ISBN 9780786435906.
  2. ^ a b c U.S. Geological Survey Geographic Names Information System: Alexander Island
  3. ^ Siple, Paul (1963). "Obituary: Carl R. Eklund, 1909–1962" (PDF). Arctic. 16 (2). Arctic Institute of North America: 147–148. doi:10.14430/arctic3531. Retrieved 19 January 2013.
  4. ^ HANDLIST OF METEOROLOGY RECORDS FROM BRITISH ANTARCTIC RESEARCH STATIONS. British Antarctic Survey Archives Service (2010)
  5. ^ "Alexander Island". Encyclopædia Britannica. 20 July 1998. Retrieved 20 January 2015.
  6. ^ Mills, William (2003). Exploring Polar Frontiers: A Historical Encyclopedia (1 ed.). p. 9. ISBN 1-57607-422-6. Retrieved 20 January 2015.
  7. ^ Smith, James A.; Bentley, Michael J.; Hodgson, Dominic A.; Cook, Alison J. (2007). "George VI Ice Shelf: Past history, present behaviour and potential mechanisms for future collapse". Antarctic Science. 19 (1): 131–142. Bibcode:2007AntSc..19..131S. doi:10.1017/S0954102007000193. S2CID 128840101.
  8. ^ Hodgson, Dominic A.; Roberts, Stephen J.; Bentley, Michael J.; Smith, James A.; Johnson, Joanne S.; Verleyen, Elie; Vyverman, Wim; Hodson, Andy J.; Leng, Melanie J.; Cziferszky, Andreas; Fox, Adrian J.; Sanderson, David C.W. (2009). "Exploring former subglacial Hodgson Lake, Antarctica Paper I: Site description, geomorphology and limnology". Quaternary Science Reviews. 28 (23–24): 2295–2309. Bibcode:2009QSRv...28.2295H. doi:10.1016/j.quascirev.2009.04.011.
  9. ^ Hodgson, Dominic A.; Roberts, Stephen J.; Bentley, Michael J.; Carmichael, Emma L.; Smith, James A.; Verleyen, Elie; Vyverman, Wim; Geissler, Paul; Leng, Melanie J.; Sanderson, David C.W. (2009). "Exploring former subglacial Hodgson Lake, Antarctica. Paper II: Palaeolimnology". Quaternary Science Reviews. 28 (23–24): 2310–2325. Bibcode:2009QSRv...28.2310H. doi:10.1016/j.quascirev.2009.04.014.
  10. ^ Public Domain This article incorporates public domain material from "Alexander Island". Geographic Names Information System. United States Geological Survey.
  11. ^ "Brahms Inlet". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved 15 August 2011.
  12. ^ "Harris Peninsula". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved 24 May 2012.
  13. ^ Hole, M.J.; Smellie, J.L.; Marriner, G.F. (1991). Thomson, M.R.A.; Crame, J.A.; Thomson, J.W. (eds.). Geochemistry and tectonic setting of Cenozoic alkalne basalts from Alexander Island, Antarctic Peninsula, in Geological Evolution of Antarctica. Cambridge: Cambridge University Press. pp. 521–522. ISBN 9780521372664.
  14. ^ Butterworth, P.J.; Macdonald, D.I.M. (1991). Thomson, M.R.A.; Crame, J.A.; Thomson, J.W. (eds.). Basin shallowing from the Mesozoic Fossil Bluff Group of Alexander Island and its regional tectonic significance, in Geological Evolution of Antarctica. Cambridge: Cambridge University Press. pp. 449–453. ISBN 9780521372664.
  15. ^ Tranter, T.H. (1991). Thomson, M.R.A.; Crame, J.A.; Thomson, J.W. (eds.). Accretion and subduction processes along the Pacific margin of Gondwana, central Alexander Island, in Geological Evolution of Antarctica. Cambridge: Cambridge University Press. pp. 437–441. ISBN 9780521372664.
  16. ^ a b Nell, P.A.R.; Storey, B.B. (1991). Thomson, M.R.A.; Crame, J.A.; Thomson, J.W. (eds.). Strike-slip tectonics within the Antarctic Peninsula fore-arc, in Geological Evolution of Antarctica. Cambridge: Cambridge University Press. pp. 443–448. ISBN 9780521372664.
  17. ^ Macdonald, D.I.M. and P.J. Butterworth (1990) "The stratigraphy, setting and hydrocarbon potential of the Mesozoic sedimentary basins of the Antarctic Peninsula." in B. John, ed., pp. 101–125. Antarctica as an exploration frontier; hydrocarbon potential, geology, and hazards. AAPG Studies in Geology. vol. 31 American Association of Petroleum Geologists, Tulsa, Oklahoma. doi:10.1306/St31524C8
  18. ^ MacDonald; Leat; Doubleday; Kelly (1999). "On the origin of fore-arc basins: New evidence of formation by rifting from the Jurassic of Alexander Island, Antarctica". Terra Nova. 11 (4): 186–193. Bibcode:1999TeNov..11..186M. doi:10.1046/j.1365-3121.1999.00244.x. S2CID 128675340.
  19. ^ Vaughan, Alan P. M.; Storey, Bryan C. (2000). "The eastern Palmer Land shear zone: A new terrane accretion model for the Mesozoic development of the Antarctic Peninsula". Journal of the Geological Society. 157 (6): 1243–1256. Bibcode:2000JGSoc.157.1243V. doi:10.1144/jgs.157.6.1243. S2CID 128496050.
  20. ^ McCarron, J. J.; Smellie, J. L. (1998). "Tectonic implications of fore-arc magmatism and generation of high-magnesian andesites: Alexander Island, Antarctica". Journal of the Geological Society. 155 (2): 269–280. Bibcode:1998JGSoc.155..269M. doi:10.1144/gsjgs.155.2.0269. S2CID 129620018.
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