Zone of permanently frozen water found in high latitude soils and sediments. Five types of permafrost have been recognized: continuous permafrost, discontinuous permafrost, sporadic permafrost, alpine [..]

The permanently frozen subsoil that lies below the upper layer (the upper several inches to feet) of soil in arctic regions.

A short term for "permanently frozen ground"; any part of the earth's crust, bedrock, or soil mantle that remains below 32? F (0? C) continuously for a number of years.

A layer of soil at varying depths below the surface in which the temperature has remained below freezing continuously from a few to several thousands of years.

Soil conditions prevailing in area whose mean annual temperature is 0o C.

1943, coined in English by Russian-born U.S. geologist Siemon W. Muller (1900-1970) from perm(anent) frost.

A layer of soil beneath the earth's surface that remains frozen throughout the year.

permanently frozen layer of the Earth's surface. Read more in the NG Education Encyclopedia

(Also called perennially frozen ground, pergelisol, permanently frozen ground.) A layer of soil or bedrock at a variable depth beneath the surface of the earth in which the temperature has been below [..]

permanently frozen subsoil. Five types: continuous permafrost, discontinuous permafrost, sporadic permafrost, alpine permafrost, and subsea permafrost.

Perennially (continually) frozen ground that occurs where the temperature remains below 0?C for several years. [8]

frozen ground. Varies widely in scope and depth and in the period of the year for which it exists. A common feature of periglacial environments. See continuous permafrost, discontinuous permafrost and [..]

Ground that is permanently frozen.

permanently frozen ground, found in polar (glacial and tundra) regions 

A permanently frozen layer of soil. Physiographic Region:

A permanently frozen layer of soil.

Any land or solid area below ground level that remains frozen (below zero degrees Celsius) for longer than two years.

Ground (soil or rock and included ice and organic material) that remains at or below 0°C for at least two consecutive years.

(n) ground that is permanently frozen

(i) permanently frozen subsurface material underlying the solum; (ii) perennially frozen soil horizon where temperature remains below 0°C throughout the year and in which Cryosols form.

A soil layer below the surface of tundra regions that remains frozen permanently.

Derived from the words permanent and frost, permafrost is a classification of soil or ground. It can be classified as continuous, discontinuous and sporadic depending on how much of the land it covers. In general, permafrost gets colder and thicker — up to 1500 meters — farther north and in some cases can melt and refreeze. Thawing of permafrost ca [..]

Ground that remains at or below freezing for at least two consecutive years.

Perennially frozen ground that occurs wherever the temperature remains below 0 degrees C for several years.

The permafrost is a layer of soil or rock beneath the surface that remains below 0oC throughout the year. It occurs when the summer warming is insufficient to reach the bottom of the layer of frozen g [..]

Ground that remains frozen throughout the year (perennially).

Subsoil which remains below freezing point throughout the year, as in polar regions.

Permanently frozen land.

Perennially frozen ground that occurs wherever temperatures remain below 0ºC for several years.

Perennially frozen ground that occurs wherever the temperature remains below 0° C for several years.

Permanently frozen subsoil.

Permafrost is soil and/or rock that remains below 0°C for at least two consecutive years, and as such moisture in the form of water or ice does not necessarily need to be present. Two forms of permafrost are present in the Antarctic Dry Valleys: in coastal areas where there is a greater availability of moisture, ice-cemented permafrost is prevalent [..]

Permanently frozen layer of soil that underlies the arctic tundra.

layer of soil or bedrock beneath earth's surface that is permanently frozen and has been for thousands of years.

Soil, silt and rock located in perpetually cold areas which remains frozen year-round. Though a thin layer may thaw during summer months, the majority of the permafrost in a given location will remain [..]

A layer of soil at varying depths below the surface in which the temperature has remained below freezing continuously from a few to several thousands of years.

Soil or other earth material with a temperature that remains below 32 degrees Fahrenheit for two or more years.

a layer of soil that is always frozen in cold regions of the world. pest

A soil layer below the surface of tundra regions that remains frozen permanently.

in arctic regions, the permanently frozen layer of soil or subsoil

A layer of soil at varying depths below the surface in which the temperature has remained below freezing continuously from a few to several thousands of years.

Perennially frozen ground in areas where the temperature remains at or below 0o C for two or more years in a row.