Geoscience Reference
In-Depth Information
Fig. 2.7
Temperature profile for a region underlain by permafrost. The
red, dashed line
depicts the
average temperature profile of the active layer and transient layer (“zero curtain”); the trumpet-
shaped
solid lines
show the seasonal temperatures during freezing and thawing. The depth of the
horizontal dashed line
(zone of seasonally invariant temperature) is approximately 10-20 m
(Source: Wikipedia)
Chemical properties of near-surface permafrost have been used to determine the
age and origin of the water and organic matter (Kokelj and Burn
2005
).
2.5
Summary
In this topic the view is taken that the permafrost-affected soil is comprised of three
parts: the active layer, the transition layer, and the permafrost layer. Soil formation
is especially pronounced in the active layer but also occurs in the transition from
warmer periods. The active layer varies from 0.1 m in high latitude environments
to more than 10 m in low-latitude mountains. The active layer shows the maxi-
mum degree of cryoturbation, may contain high amount of organic C, often is
dense from merging of freezing fronts, and may exhibit dilatancy in silt-rich soils.
