Solved cryptogram
Ground counts as permafrost once it has stayed at or below freezing for two years running.
Earth Science Facts, sourced to National Snow and Ice Data Center.
Solve it yourself
This fact is a cryptogram here: 74 letters over 21 different ones, graded hard.
Or go to the puzzle’s own page first.
What it means
The definition is about temperature and duration, not about ice, so dry rock that never thaws qualifies. A thin active layer at the top melts each summer and refreezes each winter, and everything built on the ground has to cope with that. What makes permafrost worth watching is its contents: it holds enormous quantities of undecayed plant matter, frozen before it could rot, along with the carbon locked inside it.
The claim comes from National Snow and Ice Data Center.
- SourceNational Snow and Ice Data Center
- CollectionEarth Science Facts
- Difficultyhard
- Length74 letters, 21 of them different
Nearby in the collection
The facts either side of this one.
- National Weather Servicehard, 74 letters
- National Snow and Ice Data Centermedium, 70 letters
- NASAeasy, 69 letters
- U.S. National Park Servicemedium, 77 letters
About as hard as this one
Scored closest to it by the model behind our guide to solving cryptograms.
- U.S. National Park Servicehard, 74 letters
- U.S. Geological Surveyhard, 75 letters
- U.S. Geological Surveyhard, 78 letters
- U.S. National Park Servicehard, 72 letters