PERMAFROST

3 DEFINITIONS OF ARCTIC

• the 10 degree isotherm

  • the treeline

  • arctic circle

what is PERMAFROST

Soil or rock that remains at or below 0 degree celsius for atleast 2 consecutive years!!!

Permafrost short for PERENNIALLY FROZEN GROUND

What is ACTIVE LAYER

A TOP LAYER of ground in which temp. fluctuates above and below 0 degrees C

it sits directly above the permanently frozen permafrost,

The THICKNESS of the ACTIVE LAYER depends on whtat?

• winter temp

• soil or rock type

• ground MC

• snow cover

  • surface vegetation

PERMAFROST DISTRIBUTION

Divided into 2 zones:

• CONTINUOUS

• DISCONTINUOUS

CONTINUOUS PERMAFROST ZONE

more than 80% of area is underlain by permafrost (21 Dew Line Clean Up) (DLCU) sites

DISCONTINUOUS PERMA FROST ZONE

further subdivided into subzones of:

• widespread discontinuous permafrost

  • sporadic discontinuous permafrost

How does ground ice form?

• SEGREGATED ICE - pore water gathers and grows into series of ice veins or lenses

• ICE WEDGES- surface water infiltrates cracks and freezes

• INTRUSIVE ICE- from groundwater under pressure injected into frozen ground from external source

• BURIED ICE - ice formed on ground surface and then buried by sediments

Massive Ice What is it?

Describes as large masses of ground ice

FROST ACTION

What is FROST HEAVE

• UPwarping of ground surface as a result of the formation of excess ground ice

• upward swelling of ground surface

• forming of a bump like

what is THAW SETTLEMENT

SUBSIDENCE of the ground b/c of Thawing of ground ice

what is FROST CRACKING

fracturing of the ground and the formation of ice wedges

what is UPFREEZING OF STONES

UPWARD movemnt of rocks and stones toward ground surface

what is FROST SORTING

sorting stones into symmetrical shapes such as circles, nets and polygonsSOL

what is SOLIFLUCTION

in the active layer of the ground, frost heave causes soil particles to be lifted at a right angle to the slope

LOOKS LIKE GROUND THAT IS MELTING

what is THERMAL DEGRADATION

• its a process by which ground depressions form as a result of thawing permafrost

• depression often fill with water

THERMAL DEGRADATION (what are the 2 groups?)

divided into 2 groups

• LATERAL PERMAFROST DEGRAGATION

• PERMAFROST DEGRAGATION FROM ABOVE

what is RETROGRESSIVE THAW FLOW?

a slope failure characterized by thaw of exposed ground ice and slumping of thawed soil.

THE MOST ACTIVE GEOMORPHIC FEATURES