participates in adjacent to permafrost active layer in a cryosphere permafrost thawing process active permafrost layer 2019-04-08T05:22:28Z envoNceas Potential synonyms are seasonal frost, frost zone, and mollisol. See issue #741 in GitHub for additional details. These synonyms should be validated in a cryohackathon. envoPolar A layer which is composed of ground that is 1) subject to annual thawing and freezing and 2) present in areas underlain by permafrost. active layer of permafrost