Athropolis HOME   |   Maps   |   Arctic Links   |   Arctic Library
Click to go HOME
From our library of things you should know about the Arctic


There's More Than One Type of Permafrost

Permafrost is defined as any rock or soil remaining at or below freezing temperature (colder than 32 Fahrenheit / 0 Celsius) for two or more years.

The two-year minimum does not include the surface layer that freezes every winter and thaws every summer (called the "active layer").

Permafrost is not determined by soil moisture content, snow cover, or location. It can contain a high percentage of ice - or practically no ice at all.

There are several types of permafrost:

  1. Cold permafrost: Remains below 30F / -1C or as low as 10F / -12C. It can take considerable heat without thawing.
  2. Warm permafrost: Remains just below 32F / 0C. Very little additional heat may cause it to thaw.
  3. Thaw-stable: Permafrost in bedrock, in well drained, coarse-grained sediments such as sand and gravel mixtures. Movement when thawed is minor, foundation remains essentially sound.
  4. Thaw-unstable: Poorly drained, fine grained soils, especially silts and clays. The result of thawing can be loss of strength, excessive settlement and soil containing so much moisture that it flows.
  5. Ice-rich: 20% to 50% visible ice.
MORE...
Click pictures for more information and credits.
Library: Arctic, Land, Ice
Cold/Cold Places
Links: Arctic, Environment, Cold Places
Arctic Maps & Weather Reports

Double-click any unlinked word DICTIONARY: Just "double-click" any unlinked word on this page for the definition from Merriam-Webster's Student Electronic Dictionary at Word Central.
Arctic Library ARCTIC LIBRARY & GLOSSARY: Check this section for an index of the rest of the things you really need to know about the Arctic.
All sorts of Arctic Maps ARCTIC MAPS & WEATHER REPORTS: Maps of the Northwest Passage, explorers' routes, iceberg sources, Nunavut, the Arctic by treeline, temperature...
Links to related sites. ARCTIC LINKS: Even more information! Links to sites related to the Arctic and "Iceberg: the Story of the Throps and the Squallhoots".
A Guide to Arctic Sunrise and Sunset GUIDE TO ARCTIC SUNRISE & SUNSET: How much sunlight or darkness is there in the Arctic on each day of the year?

Search for more on this topic...from Athropolis!
(1) Click the button for Web (below) to search the World Wide Web
(2) Click button for
WWW.ATHROPOLIS.COM to search this web site

 
Web WWW.ATHROPOLIS.COM
Icy Cold Jokes | Icy Games | E-mail | Athropolis HOME
Copyright 2005 Athropolis Productions Limited. The content of web sites that this site has links
to is the property of their respective owners, and Athropolis is not responsible for their content.