Page 266 - Fundamentals of Geomorphology

GLACIAL AND GLACIOFLUVIAL LANDSCAPES 249

Table 10.1 Water in the cryosphere
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Water Water volume (km ) Percentage of total Percentage of
water in hydrosphere fresh water
Total water in 1,386,000,000 100 –
hydrosphere
Total fresh water 35,029,000 100
Glacier ice and permanent 24,064,000 1.74 68.70
snow
Ground ice and 300,000 0.022 0.86
permafrost

Source: Adapted from Laycock (1987) and Shiklomonov (1993)
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These permafrost zones contain ground ice and will be to be less than 50,000 km and ice sheets more than
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dealt with in the next chapter. 50,000 km . They include ice domes, which are dome-
like masses of ice, and outlet glaciers, which are glaciers
radiatingfromanicedomeandcommonlylyinginsignif-
Glaciers icant topographic depressions. Inlandsis (a French word)
Glaciers may be classed according to their form and to are the largest and most all-inclusive scale of glacier.
their relationship to underlying topography (Sugden and They are complexes of related terrestrial ice sheets, ice
John 1976, 56). Two types of glacier are unconstrained domes, ice caps, and valley glaciers.There are two inland-
by topography: (1) ice sheets and ice caps, and (2) ice sis in Antarctica: the eastern inlandsis and the western
shelves. inlandsis (Box 10.1). The eastern inlandsis covers some
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10,350,000 km and includes three domes – the Argus
Dome, theTitan Dome (close to the South Pole), and the
Ice sheets, ice caps, and ice shelves
Circe Dome. The ice is some 4,776 m thick under
Ice sheets and ice caps are essentially the same, the only the Argus Dome. Many parts of this inlandsis attain alti-
difference being their size: ice caps are normally taken tudes in excess of 3,000 m. The Trans-Antarctic Chain

Box 10.1

ANTARCTICA

Antarctica (Figure 10.2) is the fifth-largest continent, floating ice shelves and half of the surrounding ocean
but the highest (with an average elevation exceeding freezes over in winter, more than doubling the size of
2,000 m, over twice that of Asia), the coldest, and the the continent.
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windiest. With an area of about 14,000,000 km ,itis The Antarctic ice sheet is in places more than
bigger than Australia and the subcontinent of Europe. 4,500 m thick. The ice lies in deep subglacial basins
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Ice and snow covers 13,720,000 km of the continent, and over high subglacial plateaux. The Transantarctic
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and just 280,000 km , or about 2 per cent, is ice-free. Mountains separate the two main ice sheets or inland-
With a very low snowfall, most of Antarctica is strictly sis of East Antarctica and West Antarctica. These
a desert, with the ice sheet containing almost 70 per ice sheets have different characteristics. The East
cent of global fresh water and 90 per cent of global ice Antarctic ice sheet is similar to the ice sheet cov-
reserves. Huge icebergs break off each year from the ering Greenland in that they both cover landmasses