Geology Reference
In-Depth Information
Table 10.1 Water in the cryosphere
Water volume (km
3
)
Water
Percentage of total
water in hydrosphere
Percentage of
fresh water
Total water in
hydrosphere
1,386,000,000
100
-
Total fresh water
35,029,000
100
Glacier ice and permanent
snow
24,064,000
1.74
68.70
Ground ice and
permafrost
300,000
0.022
0.86
Source:
Adapted from Laycock (1987) and Shiklomonov (1993)
to be less than 50,000 km
2
and ice sheets more than
50,000 km
2
. They include
ice domes
, which are dome-
like masses of ice, and
outlet glaciers
, which are glaciers
radiating from an ice dome and commonly lying in signif-
icant topographic depressions.
Inlandsis
(a French word)
are the largest and most all-inclusive scale of glacier.
They are complexes of related terrestrial ice sheets, ice
domes, ice caps, and valley glaciers. There are two inland-
sis in Antarctica: the eastern inlandsis and the western
inlandsis (Box 10.1). The eastern inlandsis covers some
10,350,000 km
2
and includes three domes - the Argus
Dome, the Titan Dome (close to the South Pole), and the
Circe Dome. The ice is some 4,776 m thick under
the Argus Dome. Many parts of this inlandsis attain alti-
tudes in excess of 3,000 m. The Trans-Antarctic Chain
These
permafrost zones
contain ground ice and will be
dealt with in the next chapter.
Glaciers
Glaciers may be classed according to their form and to
their relationship to underlying topography (Sugden and
John 1976, 56). Two types of glacier are unconstrained
by topography: (1) ice sheets and ice caps, and (2) ice
shelves.
Ice sheets, ice caps, and ice shelves
Ice sheets
and
ice caps
are essentially the same, the only
difference being their size: ice caps are normally taken
Box 10.1
ANTARCTICA
Antarctica (Figure 10.2) is the fifth-largest continent,
but the highest (with an average elevation exceeding
2,000 m, over twice that of Asia), the coldest, and the
windiest. With an area of about 14,000,000 km
2
,itis
bigger than Australia and the subcontinent of Europe.
Ice and snow covers 13,720,000 km
2
of the continent,
and just 280,000 km
2
, or about 2 per cent, is ice-free.
With a very low snowfall, most of Antarctica is strictly
a desert, with the ice sheet containing almost 70 per
cent of global fresh water and 90 per cent of global ice
reserves. Huge icebergs break off each year from the
floating ice shelves and half of the surrounding ocean
freezes over in winter, more than doubling the size of
the continent.
The Antarctic ice sheet is in places more than
4,500 m thick. The ice lies in deep subglacial basins
and over high subglacial plateaux. The Transantarctic
Mountains separate the two main ice sheets or inland-
sis of East Antarctica and West Antarctica. These
ice sheets have different characteristics. The East
Antarctic ice sheet is similar to the ice sheet cov-
ering Greenland in that they both cover landmasses
