Permafrost

disturbed landscapes, thaw subsidence, mud flows, and sheet and rill wash are common.
5. The Lutenga-Lena alas, silt region consists of high terraces of the Lena River. It is
dominated by Quaternary deposits, which contain large amounts of massive and
structure-forming ice and highly thaw-sensitive permafrost. Permafrost has a thickness of 300
to 420 m, Тg varies from 0 to –4.0°С, ξth from 0.7 to 2.9 m, and ξfr in alas deposits is 2.5 to
3.0 m. Surface disturbance could result in lake thermokarst. The region of the so-called
“ice-wedge complex” poses the most serious problems for railway construction.
6. The Bestyakh sand-ridge region consists of middle-height terraces of the Lena River. It
arbitrarily includes a fragment of the V terrace of the Lena River covered by eolian sands. The
thickness of uniform permafrost is 150 m. In general, the region is characterized by complicated
groundwater and permafrost conditions. Supra- and intra-permafrost water-bearing taliks are
widespread which dictate the complex patchy and layered structure of permafrost. Тg varies
from +0.5 to –6.5°, ξth is from 0.4 to 4.0 m, and ξfr is locally 2.5 to 4.0 m. Landforms produced
by piping and thermal erosion occur on the sand ridges, and seasonal and perennial frost
mounds are present on the bottoms of small valleys and on the inter-ridge depressions.
7. The Lena valley and forest-steppe, sandy silt–sand region covers the floodplain and low
terraces of the Lena River. Unfrozen ground masses, transient and irreversible frozen and
thawed layers, as well as ‘aprons’ and ‘islands’ of frozen ground determined by the hydrologic
regime of the Lena River are widespread in the region. Permafrost thickness increases with
increasing distance from the river channel from a few meters to 300 m. Тg varies from –0.1 to
–3.5°С, ξth from 1.2 to 3.5 м, and ξfr ranges locally from 2.5 to 4.0 m.
Key words: Physiographic region, permafrost landscape, engineering geocryological condition
Preliminary Permafrost Maps of Antarctica
J.G. Bockheim 1 , J. Boelhouwers 2 , I.B. Campbell 3 , B.D. Gore 4 , M. Guglielmin 5 , C.A. Hallam 6 , J.
López-Martinez 7 , M. McLeod 8
(1.Department of Soil Science, University of Wisconsin, Madison, WI 53706-1299, USA;
2.Department of Earth Sciences, Uppsala University, Uppsala, Sweden ,S 752 36;
3.Land & Soil Consultancy Services, Nelson, New Zealand;
4.Department of Physical Geography, Macquarie University, Sydney, Australia;
5.Insubria University, Varese, Italy; 6.U.S. Geological Survey, Reston, VA 20192;
7.University of Madrid, Madrid, Spain 28049; 8.Landcare Research, Hamilton, New Zealand)
Abstract: Only 0.33% of the 14 million km 2 Antarctic region (>60ºS) is ice-free. Ice-free areas,
which include exposed bedrock as well as unconsolidated materials, can be divided into eight
subregions. The Transantarctic Mountains (TAM), which bisect the continent, contain about
45% (20,000 km 2 ) of the ice-free area. The Antarctic Peninsula and its offshore islands
constitute the second largest ice-free area at 13,600 km 2 (35% of area). The other ice-free
regions, including the Vestfold Hills, Queen Maud Land, the Pensacola Mountains, the
Ellsworth Mountains, Marie Byrd Land, Enderby Land, and Wilkes Land, contain the
remaining 20% of the ice-free area. The McMurdo Dry Valleys (MDV, 4,800 km 2 ) in the central
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