permafrost

permafrost

permafrost, permanently frozen soil, subsoil, or other deposit, characteristic of arctic and some subarctic regions; similar conditions are also found at very high altitudes in mountain ranges. In 1962 measurements in a borehole drilled on Melville Island, Northwest Territories, Canada, showed that the ground was frozen to a depth of at least 1,475 ft (450 m); comparable thicknesses have been found in other far north regions. Tundras, though underlaid by permafrost, today support centers of population in Alaska, Canada, and Siberia. Permafrost is a very fragile system that may easily be damaged or destroyed by the presence of human-generated heat. A controversy developed in the late 1960s and early 70s over the construction of an oil pipeline from the Alaska North Slope to the southern part of the state. Critics of the project argued that if the pipeline containing hot oil ever came into contact with the permafrost, it would melt the permafrost; the pipeline would then sink and eventually break. The oil spilled during the breakage would result in a major ecological disaster. It was decided to build the pipeline with insulated pipe raised above the permafrost or on gravel beds in order to prevent melting and thus preserve both the pipeline and the ecosystem. In the 21st cent., as the effects of global warming have become particularly strong in the Arctic, permafrost has thawed and destabilized, resulting in dramatically altered landscapes in some areas.

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Permafrost

 

a vague term of many meanings applied to the phenomenon of the cooling of rocks on the upper part of the earth’s crust to temperatures of zero and below; the rocks themselves that have hardened as a result of the freezing of the moisture they contained; and the stratum (layer) or zone (region of horizontal spread) of rocks that do not thaw for a long time.

The term “permafrost” was introduced into scientific usage in 1927 by the founder of the school of Soviet geocryologists, M. I. Sumgin, who defined it as ground frost that exists for two to several thousand years. The phrase “ground frost” was not clearly defined in this formulation, and this led to the use of permafrost in various meanings.

As geocryology developed, investigators found themselves increasingly inconvenienced by the word “permafrost,” and as a result it was sharply criticized by P. F. Shevtsov, L. A. Meister, and others in the 1950’s at the V. A. Obruchev Institute of Geocryology of the Academy of Sciences of the USSR. This led to a prolonged discussion of all geocryological terminology. Of the many scientific terms suggested to replace “permafrost,” “perennial frozen rocks” and “perennial cryolithozone” are in widest use.

REFERENCES

Osnovy geokriologii (merzlotovedeniia), parts 1-2. Moscow, 1959.
Materialy po obshchemu merzlotovedeniiu. Moscow, 1959.
Popov, A. I. Merzlotnye iavleniia v zemnoi kore (kriolitologiia). Moscow, 1967.
Dostovalov, B. N., and V. A. Kudriavtsev. Obshchee merzlotovedenie. Moscow, 1967.

A. E. SNOPKOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

permafrost

[′pər·mə‚frȯst]

(geology)

Perennially frozen ground, occurring wherever the temperature remains below 0°C for several years, whether the ground is actually consolidated by ice or not and regardless of the nature of the rock and soil particles of which the earth is composed.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

permafrost

Permanently frozen soil, subsoil, or other deposits in arctic or subarctic regions.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

permafrost

ground that is permanently frozen, often to great depths, the surface sometimes thawing in the summer

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005