1 / 17

Permafrost

Permafrost. ESS 315. What is Permafrost. 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.

lael
Download Presentation

Permafrost

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Permafrost ESS 315

  2. What is Permafrost • 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.

  3. Types of Permafrost • 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.

  4. Thermokarst Lakes • Formed in depressions by melting from thawing permafrost • Freshwater and usually Shallow

  5. Solifluction - Slow down slope flow of saturate unfrozen earth minerals

  6. Ground Patterns

  7. Not juston Earth…

  8. Zones of Permafrost • 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.

  9. Location of Permafrost in North

  10. Creation of Permafrost • Deep permafrost takes thousands of years to create.

  11. Construction on Permafrost • 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

  12. Construction on Permafrost • Additionally, sinking can be prevented by using stilts that extend to a depth of over 15 meters.

  13. The Alaska Pipeline • 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.

  14. Pipeline Designs • Above-ground pipeline: • Problems from melting are avoided in thaw-unstable areas by placing the pipeline on an elevated support system above ground.

  15. Pipeline Designs • 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.

  16. Ecological Problems • Animals will not be able to effectively burrow or create dens. • Plant roots are constrained to grow in a near-surface pattern

  17. Works Cited: • 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

More Related