close-up of thaw slump
close-up of thaw slump, Noatak National Preserve
  • Obvious slump in the land near body of water

    Thaw slump caused by permafrost melt, Noatak National Preserve

  • close-up of thaw slump

    close-up of thaw slump, Noatak National Preserve

Permafrost Lingo

  • Permafrost

    ground that remains frozen longer than two consecutive years; ground that doesn't thaw in the summer due to the cold climate in which it's found
  • Active Layer

    in areas with permafrost, the top portion of the soil that melts and refreezes each year
  • Ice Wedge

    polygon-like pattern of landscape associated with permafrost caused by repeated cycles of melting, freezing and cracking
  • Thermokarst

    landscape formations associated with permafrost melt
  • Slump

    a term that refers to the sagging or degradation of the landscape caused by permafrost melt
  • Hydrology

    the study of the location, movement, and quality of water on earth; heavily influenced by permafrost in arctic systems
  • Erosion

    the transport of soil and rock from earth's surface by wind or water; a significant effect of permafrost melt

Permafrost in Alaska's National Parks

Permafrost is permanently frozen ground and underlies much of the landscape in the arctic. If affects nearly everything in the arctic ecosystem, including soils, vegetation, water, and wildlife. During summer months, the top layer of soil thaws creating a wet landscape with rapid runoff. The striking quilt-like pattern of permafrost landscapes is caused by the build-up and thawing of ice in the ground, which produces pits, ponds, and landslides. Annual permafrost melt is normal, but melt is expected to increase with climate change. The National Park Service is monitoring permafrost and the land features associated with permafrost melt to better understand the changes and the effects of increased permafrost melt.


Live Chat with Permafrost Experts

On August 14, 2012, permafrost experts with the National Park Service hosted a virtual open forum and answered questions from the public via Facebook, Twitter, and email. See posts from the live chat on Facebook.

Video Features

National Parks with Permafrost

The following National Park Service units contain areas with permafrost




Additional Resources

Permafrost Photos

Permafrost Photo Gallery
Last Update April 9, 2014