West Antarctica

West Antarctica, but not at the very dry sites in East Antarctica. In addition to such continual counting methods, one can determine the absolute age of ice by identifying the fallout from volcanic eruptions of known age. 

Fig. 18-13 High-resolution measurements of CO2 over the last glacial-interglacial transition from the Byrd ice core in west Antarctica (Neftel et ai, 1982). Also plotted is the oxygen isotope record temperature proxy from the Byrd core (Johnsen et ai, 1972). The time scale for the records plotted here is from Sowers and Bender (1995).

Fig. 18-17 Ice core records of N2O. (a) Data of Machida et al. (1995) from the H15 ice core, east Antarctica, for the time period 1750-1950, and monthly atmospheric N2O measurements at the South Pole from the NOAA Climate and Diagnostics Laboratory, Boulder, CO, for the period 1989-1998. (b) Data from Leuenberger and Siegenthaler (1992) from the Byrd ice core in West Antarctica.

Greenland, N03-, Cl , Na+, and A1 or microparticles have usable seasonal variations. Sea salt-derived Na and Cl are useful dating species in East Antarctic snow although the variations are lower than in Greenland and the dating errors are consequently higher. Sea salts are satisfactory seasonal indicators in the inland portion of the Ross Ice Shelf and presumably in West Antarctica. Nitrate and sulfate have good seasonal variations on the Ross Ice Shelf, even at the more seaward locations. 

Sun L, Yin X, Liu X, Zhu R, Xie Z, Wang Y (2006) A 2000-year record of mercury and ancient civilizations in seal hairs from King George Island, West Antarctica. Science of the Total Environment 368 236-247... 

Glaciers in West Antarctica thinned much faster in 2002 and 2003 than in the 1990s. 

Late Holocene Deglaciafion of Marie Byrd Land, West Antarctica Science, 299, 99—102. 

Ackert RP Jr, Barclay DJ, Boms HW Jr, Calkin PE, Kurz MD, Fastook JL, Steig EJ (1999) Measurements of past ice sheet elevations in interior west Antarctica. Science 286 276-280 Althaus T, Niedermann S, Erzinger J (1998) Noble gases in ultramafic mantle xenoliths of the Persani Mountains, Transylvanian Basin, Romania. Mineral Mag 62A 43-44 Anderson RS, Repka JL, Dick GS (1996) Explicit treatment of inheritance in dating depositional surfaces using in situ e and A1. Geology 24 47-51... 

Bentley, C. R. (1997) Rapid sea-level rise soon from West Antarctica Ice Sheet collapse Science 275, 1077-1078. 

Captain James Cook was the first person to circumnavigate Antarctica between 1772 and 1775 during his three voyages of exploration into the Pacific Ocean (Beaglehole 1955,1961,1962,1967 Bellec2000). On January 30, 1774, Captain Cook reached a point near the coast of West Antarctica at 71°10 S, 106°54 W. 

The ship was equipped with two steam engines and carried 335 t of coal. The expedition left England in August of 1901 and reached Lyttelton Harbor on the South Island of New Zealand at the end of November of the same year. After restocking the ship with provisions, the expedition headed south to Cape Adare and followed the coast of Victoria Land to Ross Island. From there, Scott sailed east along the edge of the Ross Ice Shelf to the coast of West Antarctica which he named King Edward VII Land. 

During the 1934/35 field season Byrd s teammates explored large areas of West Antarctica and measured the thickness of the Ross Ice Shelf (90 m) as well as the depth of the water in which it floated (600 m). All of the various field parties returned to Little America 11 in January of 1935 and were picked up by the ships in Eebruary. Although Byrd and his men had explored large areas in the Ross-Sea sector of Antarctica, the US government did not formally claim these territories as other nations had done (e.g., Britain, New Zealand, Norway, and France). 

Set up permanent bases at the Bay of Whales and on Stonington Island (68°11 S, 067°00 W) from which West Antarctica was mapped by aerial photography combined with ground truths established by dog sled teams. 

Webers et al. Geology and paleontology of the Ellsworth Mountains, West Antarctica... 

Webers GF Craddock C, Splettstoesser JF (eds) (1992) Geology and paleontology of the EUsworth Mountains, West Antarctica. Memoir 170, The Geological Society of America, Boulder, CO... 

The area of Antarctica is 13.97 x 10 km making it the fifth largest of the seven continents (Stonehouse 2002). It is conventionally oriented on maps as shown in Fig. 2.1 and is subdivided into East Antarctica, West Antarctica, the Antarctic Peninsula, and certain islands that rise more than 500 m above sea level (i.e., Alexander, Bear, Berkner, Roosevelt, Ross, and Thurston). In addition, Antarctica is surrounded by the Ross, Ronne, Filchner, Riiser-Larsen, Fimbul, and Amery floating ice shelves as well as by the Larsen ice shelf located along the east coast of the Antarctic Peninsula. Except for the northernmost tip of the Antarctic Peninsula, the continent lies within the Antarctic Circle at latitudes greater than 62.5° south. 

Fig. 2.1 Antarctica is conventionally oriented as shown and is subdivided into East Antarctica, West Antarctica, and the Antarctic Peninsula. The Transantarctic Mountains extend from northern Victoria Land along the Ross Sea and the Ross Ice Shelf toward the Pensacola Mountains adjacent to the...

Mountains of East Antarctica, in the Ellsworth Mountains of West Antarctica, and in the extinct volcanoes of Marie Byrd Land. In addition, small mountain ranges project through the East Antarctic ice sheet in Queen (or Dronning) Maud Land, in Enderby Land, in Mac. Robertson Land, and in a few places in Wilkes Land (e.g., Gaussberg, Section 1.3.3). 

The Sentinel Range of the Ellsworth Mountains in West Antarctica (Fig. 2.1) includes the Vinson Massif which contains the highest peak in Antarctica at 4,901 m (Stonehouse 2002). The highest peaks of the Transantarctic reach an elevation of 4,528 m in the Queen Alexandra Range along the north side of the Beardmore Glacier (National Geographic Society 1990). 

The present elevation of the bedrock surface of some parts of East and West Antarctica is actually below sea level. Eor example, two large subglacial basins in Wilkes Land of East Antarctica lie below sea level. In addition, the surface of subglacial Lake Vostok at 78°28 S and 106°48 E is below sea level by about 200-300 m. The bedrock surface of most of West Antarctica is also below sea level partly because of the mass of the overlying ice sheet (Drewry et al. 1983 Bentley and Robertson 1982 Bentley et al. 1982). Consequently, the incursion of seawater into the subglacial basins could result in the hreak-np of the West Antarctic ice sheet and of the ice in the Wilkes basin of East Antarctica. 

The volcanoes of Antarctica occur not only in the Transantarctic Mountains and on the islands off the coast of Victoria Land, but also in Marie Byrd Land of West Antarctica, on the Antarctic Peninsula and on its off-shore islands, on the South Sandwich Islands, in East Antarctica, and on the islands of the Southern Oceans. All of these volcanoes were described in a book edited by LeMasurier and Thomson (1990). The descriptions of the volcanoes include photographs, maps, chemical analyses of the rocks, and interpretations of these analyses. Even the Gaussberg on the coast of East Antarctica (Section 1.3.3) is included in this compilation of Antarctic volcanoes. The book also... 

The volcanoes in the Transantarctic Mountains and in Marie Byrd Land of West Antarctica erupted lava flows and pyroclastic ash that was deposited on the surface of the ice sheets. The ash was subsequently buried by snow and was thereby incorporated into the ice. The resulting ash layers now serve a useful purpose in the study of the ice sheets because they are unique event horizons whose age can be determined by isotopic methods (e.g., Folco et al. 2007). In addition, these horizons have preserved a record of the deformation of the ice sheets that is revealed by mapping their outcrop patterns on the bare-ice surfaces in the ablation zones. The chemical composition of the ash has been used to identify the volcanoes from which certain ash layers were erupted, while the sulfate concentration and the acidity (pH) of the ice above an ash layer provide clues to the amount of sulfuric acid that was injected into the stratosphere (Palais 1985). The volcanic dust and sulfuric acid in the stratosphere can cause temporary cooling of the global climate as demonstrated by the eruptions of Krakatau (Indonesia) in 1883, Mount St. Helens (Washington) in 1980, El Chichon (Mexico) in 1982, and Mount Pinatubo (Philippines) in 1992 (Holland and Petersen 1995 Thompson and Mosley-Thompson 1981 Kyle et al. 1981 Self etal. 1981). 

American scientists and support personnel who are scheduled to work in the Transantarctic Mountains or on the polar plateau of East Antarctica, in Marie Byrd Land in West Antarctica, and at South Pole Station will, in most cases, depart from Christchurch, New Zealand, and fly to McMurdo Station which is located at the tip of the Hut Point Peninsula on Ross Island in Fig. 2.8 (Section 1.2). This site was originally selected in 1955 by Admiral George J. Dufek as a logistics base for Operation Deep Freeze in preparation for research to be carried out by American scientists during the IGY (1957-1958). The site was chosen because it is located in a broad basin adjacent to a deep harbor where supply ships can unload cargo either onto a floating ice dock or directly to the shore. These favorable conditions also caused Robert Scott in 1901 to select this site for his winter-over base where he set up his Discovery Hut in Fig. 2.9 which still contains some of the equipment and supplies that he and his men left behind (Section 1.4.1). 

Fig. 2.18 The tractor train of the Meirie-Bytd-Land oversnow traverse left Byrd station in West Antarctica on November 1, 1958, as part of the exploration of Antarctica during the IGY. The...

Bentley CR (1983) Crustal structure of Antarctica from geophysical evidence a review. In Oliver RL, James PR, Jago JB (eds) Antarctic earth science. Australian Academy of Science, Canberra, ACT, Australia, pp 491-497 Bentley CR, Robertson JD (1982) Isostatic gravity anomalies in West Antarctica. In Craddock C (ed) Antarctic geoscience. University of Wisconsin Press, Madison, Wl, pp 949-954 Bentley CR, Robertson JD, Greischar LL (1982) Isostatic gravity anomalies on the Ross Ice Shelf. In Craddock C (ed) Antarctic geoscience. University of Wisconsin Press, Madison, Wl, pp 1077-1081... 

Fig. 8.4 The granitic plutons of the nunataks located in a belt in West Antarctica between the Thiel Mountains and the Ellsworth Mountains were intruded during the Jurassic Period. The dates of these plutons are listed in Appendix 8.6.5 (Adapted from Vennum and Storey 1987a)...

West Antarctica which crystallized at 1058 53 and 1003 18 Ma, respectively. A similar whole-rock Rb-Sr date of 980 16 Ma (recalculated to /V = 1.42 x 10 " year ) was reported by Eastin and Faure (1971) for rhyolites in the Littlewood and Bertrab nunataks at 77°53 S, 034°10 W in Coats Land on the east coast of the Weddell Sea (Section 9.4). However, the relationship between the Haag Nunataks and the small nunataks of Coats Land can only be understood in the context of the rifting of Rodinia and the departure of Laurentia which are the subjects of Chapter 9. 

The Ellsworth Mountains of West Antarctica in Eig. 8.4 are composed of a thick sequence of highly folded and low-grade metasedimentary and metavolcanic rocks which range in age from Proterozoic to Permian (Craddock et al. 1964a, 1986 Craddock 1969 a Schopf 1969 Webers et al. 1992). Although volcanic rocks do occur in the Heritage Group of Neoproterozoic... 

Fig. 8.5 Historical photograph of a US Navy R4D-8 (modified DC-3 on skis) that landed on Janutiry 23,1960 in the Nash Hills at 81°53 S, 89°23 W in West Antarctica. The scientists on that...

Mountains and the enigmatic tectonic provinces that together constitute West Antarctica. (Cited by Tessensohn and Thomson 1999, p. 175)... 

Kovach J, Faure G (1978) Rubidium-strontium geochronology of granitic rocks from Mt. Chapman, Whitmore Mountains, West Antarctica. Antarctic J US 13(4) 17-18 Leat PT, RQey TR, Storey BC, Kelley SP, Millar IL (2000) Middle Jurassic ultramafle lamprophyre dyke within the Ferrar magmatic province, Pensacola Mountains. Antarctica Mineral Mag 64 95-111... 

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