Polar Plateau

The activity of 2,3-oxidosqualene cyclases is associated with microsomes, indicating their membrane-bound nature. However, the predicted amino acid sequences of these enzymes generally lack signal sequences and obvious transmembrane domains. Addition of hydrophobic membrane-localising regions to OSCs during evolution may have removed selection pressures that maintained alternate mechanisms for membrane localisation [33]. Consistent with this, there is a non-polar plateau on the surface of the A. acidocaldarius SC enzyme which is believed to be immersed in the centre of the membrane. The squalene substrate for SC is likely to diffuse from the membrane interior into the central cavity of the enzyme via this contact region [55,56]. 

From data of measurements at the South Polar Plateau the mean bulk aerosol density varies from 15 particles/cm (in winter) to 100-150 particles/cm (in summer). A prevailing size of particles lies within 0.02-0.2 pm. In summer, at the expense of downward air fluxes, the values Cn = 500-1,500 cm were registered. This jump attributed to the appearance in the Antarctic air of considerable concentrations of particles... 

Hogan A.W., Meteorological transport of particulate material to the South Polar Plateau. J. Appl. Meteorol. , 18 (6), 741-749 (1979). 

Scott later led a nine-man party west across McMurdo Sound to continue the exploration of Victoria Land. They reached the polar plateau and traveled across its empty vastness for 450 km before returning to Hut Point in time for Christmas of 1903. About 2 weeks later, two relief ships, the Morning and the Terra Nova, appeared at the ice edge some 32 km from Hut Point. Fortunately, the sea ice in McMurdo Sound began to break up in early February and all three ships were able to sail north together. 

Shackleton was personally interested in reaching the geographic South Pole and therefore began laying depots for the trek south as soon as the weather permitted in September of 1908. On October 28 a group of four men led by Shackleton (i.e., Jameson Adams, Eric Marshall, and Frank Wild) headed south across the Ross Ice Shelf. They reached the mouth of the Beardmore Glacier and followed it up to the polar plateau. The team continued toward the South Pole by man-hauling on limited rations. On January 9 of 1909, at 88°23 S and 162°E, they were only 97 miles from... 

Fig. 1.19 The route taken by Amundsen and his men led directly from Framheim at the Bay of Whales to the mouth of the Axel Heiberg glacier which they used to reach the polar plateau and hence the South Pole. They started the trip on October 20, 1911, with four sleds, each of which was puUed by 13 dogs. Amundsen selected experienced men to drive the sleds and made rapid progress across the Ross Ice Shelf. The ascent of the Axel Heiberg glacier was difficult because it is steep and heavily cre-vassed. The group required 5 days to traverse the glacier and to reach the polar plateau. They arrived at the South Pole on December 14 of 1911 (Adapted from Stonehouse 2002)...

The local conditions that affect the weather alluded to above include the katabatic wind that blows from the polar plateau through the valleys of the outlet glaciers in the Transantarctic Mountains. The wind is generated when the layer of cold air that forms directly above the surface of the polar plateau drains downslope toward the coast. The speed of the wind on a gentle slope... 

Fig. 2.4 During whiteout conditions in the Transantarctic Mountains the horizon becomes invisible and surface definition is lost. In the case shown here, the whiteout conditions resulted from high wind associated with snowfall near the coast of northern Victoria Land. The Scott tent, strU used by geological fieldpar-ties in the Transantarctic Mountains and on the polar plateau, is well suited for use in cold and windy weather, especially when it is set up in well-packed snow or neve. Mills Valley, Pain Mesa, northern Victoria Land, December 1982 (Photo by G. Faure)...

The effects of the low air temperatures in the Transantarctic Mountains are magnified by wind which accelerates the loss of heat from the human body. This phenomenon is expressed quantitatively by the wind-chill scale (Rees 1993) that converts the measured temperature into an equivalent wind-chill temperature. For example, the arrow in Fig. 2.5a indicates that the measured air temperature of -10°C at a wind speed of 8 m/s corresponds to a wind-chill temperature of-20 C. In addition, a wind speed of 8 m/s in Fig. 2.5b is equivalent to a speed of 28.8 km/h. The wind-chill temperature also permits the definition of the discomfort index in Table 2.1. Accordingly, a wind-chill temperature of -20°C is perceived as being bitterly cold. Such conditions are not unusual during the austral sununer on the polar plateau and in the Transantarctic Mountains, except along the coast. 

The discomfort experienced by humans because of the cold and windy conditions that characterize the summer weather in the Transantarctic Mountains and on the polar plateau is aggravated by the extremely low humidity of the air. Humans working out-of-doors under these conditions must protect themselves by wearing appropriate cold-weather clothing. Their ability to cope with the stressful environmental conditions improves when they are physically fit, well rested, well nourished, healthy, and when they are highly motivated to accomplish their mission (Gunderson 1974). 

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). 

Former residents of McMurdo Station will also recall the windstorms that suddenly reduce visibility to less than 100 ft (30.48 m), with wind speeds in excess of 55 knots (101.9 km/h), and wind-chill temperatures that drop below -100°F (-73.3°C). Under these conditions, all personnel in McMurdo are required to remain in-doors (Condition 1) and all travel is suspended for the duration of the storm that may last several days. The classification of weather conditions detailed in Table 2.3 is the responsibility of the McMurdo Weather Office (Mac Weather). Condition 1 storms can occur anywhere within the Transantarctic Mountains during the austral spring and fall especially on major outlet glaciers, such as the Reedy Glacier in Fig. 2.11, that channel the katabatic winds from the polar plateau to the Ross Ice Shelf or to the Ross Sea. Field parties that experience such storms learn first-hand that weather still rules in Antarctica. 

Fig. 3.5 The western end of Wright Valley in southern Victoria Land is framed by the Olympus Range in the north and the Asgard Range in the south. Ice from the East Antarctic ice sheet of the polar plateau enters the valley via the Airdevronsix icefaU and forms the Wright Upper Glacier. The Labyrinth at its base was carved by meltwater streams flowing under pressure at the base of a glacier that once flUed the Wright Valley. Lake Vanda is peren-...

Fig. 3.6 The Balham, Barwick, Victoria, and McKelvey valleys of southern Victoria Land are ice-free because the flow of ice from the polar plateau via the Webb Glacier and the Upper Victoria Glacier is currently restricted. These valleys therefore expose metamorphic and granitic igneous rocks of the basement complex overlain unconformably by the Lower Devonian sandstones of the...

Mt. Murchison, 3,500 m Mt. Herschel, 3,335 m and Mt. Phillips, 3,036 m). The elevations of the mountains west of the Rennick Glacier reach only 2,828 m (Roberts Butte), 2,494 m (Welcome Mountain), 2,402 m (Mt. Southard), and 2,257 m (Mt. Weihaupt). The polar plateau west of the Daniels Range rises to an elevation of about 2,500 m above sealevel (Adapted from Borg et al. 1986 Gair et al. 1969 National Geographic Society 1990)... 

The basement rocks of the Wilson Terrane are well exposed in the Wilson Hills and in the Daniels Range of the USARP Mountains as well as in the Emlen Peaks, on Welcome Mountain, and at Mt. Southard (Gair et al. 1969 Sturm and Carryer 1970 Tessensohn et al. 1981). Even though these mountain ranges are located adjacent to the polar plateau, Archean and Paleoproterozoic granulites of the East Antarctic era-ton have not been recognized in the Wilson Terrane or anywhere else in northern Victoria Land. 

The basement rocks of the central Transantarctic Mountains are exposed primarily along the coast, except for the Geologist and the Miller Ranges which are located at the edge of the polar plateau more than 80 km inland of the coast The basement rocks along the coast are unconfonnably overlain by the sedimentary rocks of the Beacon Supergroup which were intruded... 

The Transantarctic Mountains were a formidable barrier which the pole seekers had to overcome in order to reach the polar plateau (Section 1.4). Ernest Shackleton and Robert Scott forced their way up the Beardmore Glacier, whereas Roald Amundsen climbed the Axel Heiberg Glacier which he named after one of his supporters in Norway. After 4 days of intense effort he and his men, with the help of 42 dogs, reached the polar plateau on November 21, 1911 (Huntford 1987). Amundsen also named the Queen Maud Mountains after the reigning Queen of Norway (Section 1.4.4). 

Fig. 6.12 The Scott Glacier flows north from the polar plateau and discharges ice into the Ross Ice Shelf. The Bartlett and Albanus glaciers are its principal tributaries. The major mountain ranges adjacent to the Scott Glacier are the La Gorce Mountains at its head and the Tapley Range east of its mouth. In addition, the map identifies Mt. Weaver, Mt. Wyatt, Mt. Gardiner, and Mt. Blackburn. The valley of the Leverett Glacier is located east of the Scott Glacier and drains the Harold Byrd Mountains to be discussed in Section 6.5 (Adapted from Mirsky 1969)...

The coal-bearing Weller Formation is overlain by the Feather Conglomerate which is prominent at Mt. Feather (Fig. 10.2), but which also occurs on Mt. Fleming (Fig. 10.5) and on Portal Mountain located at the edge of the polar plateau. The Feather Conglomerate is 160 m thick, according to McKelvey et al. (1970), and was deposited by braided streams during the Permian Period (Barrett and Fitzpatrick 1985). 

Fig. 10.8 The Hatherton Glacier flows from the polar plateau between the Darwin Mountains on the right and the Britannia Range on the left. Both mountain ranges in this area consist of sedimentary rocks of the Beacon Supergroup that were intruded by sills of Jurassic Ferrar Dolerite.

The Westhaven Nunatak at the edge of the polar plateau is composed of the Jurassic Kirkpatrick Basalt. Aerial photograph from US Geological Survey, Earth Explorer, US Antarctic Indexes, TMA 1011, roll 00031L, frame 43, November 13, 1962... 

Fig. 10.11 Erosional remnants of the Beacon Supeigioup occur on the nunataks in the Rennrck basin and on its western edge along the polar plateau in northern Victoria Land. The formations are of Permian and Triassic age and belong to the Victoria Group. Rocks of the Devonian Taylor Group are not present in northern Victoria Land (Adapted from Gair et al. 1969)...

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