PBS
Newton's Apple: Permafrost
How can something be preserved for 30,000 years? How can humans adapt to permafrost? What can permafrost tell us about our past and future climate? These questions are answered in this concise site.
Other
Alyeska Pipeline: Pipeline Facts
This site from Alyeska Pipeline defines permafrost and explains the various types of permafrost that can be found. The effect of permafrost on the building of the Alaskan Pipeline is examined.