Geologic Monitoring

What is permafrost?

Permafrost is ground that remains at or below 0 °C for at least two consecutive years. Permafrost resides beneath a surficial "active layer" that freezes and thaws each year.

Most permafrost is located in high latitudes. Approximately 80% of Alaska is underlain by permafrost. But mountain permafrost may exist at high altitudes in lower latitudes, such as in western North America and on Mount Washington in New Hampshire.

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Why does the National Park Service monitor permafrost?

The condition of permafrost is of interest to the National Park Service for two primary reasons.

• Because ice helps to bond slope deposits, landslides and thaw slumps are expected to occur in mountainous areas if the permafrost thaws.
• Permafrost impedes subsurface drainage, creating wet to moist conditions that provide good habitat for many alpine plant species. Thawing of permafrost would increase drainage and dry the soil, thus impacting the vegetation.