ESS 315

Any rock/soil at or below the freezing point of water.

Remains below 0 degrees Celsius continuously for two years.

Ice is not necessarily present. The ‘active layer’ is the overlying surface

that freezes in the winter, and thaws in the summer.

Cold Permafrost: Tolerates considerable heat without thawing. Remains between 10 – 30°F.

Warm Permafrost: Introducing very little heat may cause thawing. Just below 34°F.

Ice Rich: 20% - 50% visible ice. Thaw-Stable: Permafrost in bedrock is well-

drained. Coarse grained sediments. Thaw-Unstable: Poorly drained, fine-

grained sediment (clays and silts). Thawing results in so much moisture that it flows.

Formed in depressions by melting from thawing permafrost

Freshwater and usually Shallow

Solifluction - Slow down slope flow of saturate unfrozen earth minerals

Continuous Zone – Permafrost is found almost everywhere in the zone.

Discontinuous Zone – Permafrost found in spots in the zone.

Sporadic Zone – Permafrost found isolated in small spots of the zone.

Deep permafrost takes thousands of years to create.

Heat from a building or other constructed article will cause thawing, and can result in sinking.

Three solutions are common:◦ Using foundations on wood piles◦ Building on a thick gravel pad◦ Using anhydrous ammonia heat pipes

Additionally, sinking can be prevented by using stilts that extend to a depth of over 15 meters

Additionally, sinking can be prevented by using stilts that extend to a depth of over 15 meters.

Approximately 75% passes through permafrost terrain.

Special designs are created to account for the movement, melting, and freezing characteristics of the ground.

There are three principal designs used to construct the pipeline. The design varies from area to area.

Above-ground pipeline:◦ Problems from melting are avoided in thaw-

unstable areas by placing the pipeline on an elevated support system above ground.

Below-ground, conventional burial:◦ In areas where thaw-stable or unfrozen ground is

encountered, the pipeline can be buried with no special provisions.

Below-ground, special burial:◦ Where thaw-unstable permafrost is encountered,

but the pipeline must be buried for highways, animal crossings, rockslides/avalanches, etc.

◦ The pipeline is insulated so that the heat it produces does not promote melting.

Animals will not be able to effectively burrow or create dens.

Plant roots are constrained to grow in a near-surface pattern

Alaska Pipeline- http://www.alyeska-pipe.com/pipelinefacts/Permafrost.html

International Permafrost Association - http://ipa.arcticportal.org/

http://planetparadigm.wordpress.com/2009/02/05/global-climate-change-forget-the-climate-models-wheres-the-real-evidence/

http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/climate_systems/climate_change.html