frozen ground or permafrost

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approximate thawing index

the cumulative number of degree-days above 0 degrees Celsius for a given time period, calculated from the mean monthly temperatures for a specific station without making corrections for negative degree-days in spring and fall.

artificial ground freeezing

the process of inducing or maintaining a frozen condition in earth materials by artificial means.

banded cryogenic fabric

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers.


areas of discontinuous vegetation cover in the polar semi-desert of the high arctic.

basal cryopeg

a layer of unfrozen ground that is perennially cryotic (t < 0 degrees Celsius), forming the basal portion of the permafrost.

basal cryostructure

the cryostructure of a frozen deposit of boulders that is saturated with ice.

basal-layered cryostructure

the cryostructure of a frozen layered deposit of gravel and boulders that is saturated with ice.

beaded stream

a stream characterized by narrow reaches linking pools or small lakes.


hard-packed rock lying below the Earth’s surface; lies in beds or layers; can be variable across geographic space; above bedrock is a layer of broken, weathered rock.

block field

a surficial layer of angular shattered rocks formed in either modern or pleistocene periglacial environments.