冻土层

permafrost / tundra / layer of frozen soil

to freeze / to feel very cold / aspic or jelly

frozen earth / permafrost / tundra

Tu (ethnic group) / surname Tu

earth / dust / clay / local / indigenous / crude opium / unsophisticated / one of the eight categories of ancient musical instruments 八音[ba1 yin1]

layer of soil / ground level

to pile on top of one another / layer; stratum / floor (of a building); story / (math.) sheaf / classifier for layers