Geoscience Reference
In-Depth Information
Fig. 2.5
Distribution of permafrost in the Northern Hemisphere (Brown et al.
1997
)
2.4.3
Permafrost Properties
The thickness of permafrost ranges from less than a meter near its southernmost
(Northern Hemisphere) or northernmost (Southern Hemisphere) boundary to over
1,500 m in northern Siberia. Buried ice in the Antarctic Dry Valleys may be 8 Ma in
age (Marchant et al.
2002
); ice-bonded permafrost in central Siberia is about 3 Ma
in age and retains viable microorganisms (Gilichinsky et al.
1992
). Permafrost tem-
peratures are often reported as the Mean Annual Ground Temperature (MAGT),
which is normally recorded at the 10-m or 20-m depth, and Temperature at the Top
of Permafrost (TOPP). The temperature of permafrost ranges from near 0 ﾰC
