What term means water perpetually frozen in soil or rock?

• A. Permafrost
• B. Glacier
• C. Ice cap
• D. Ground ice

Answer: (A)

Permafrost is the ground that remains frozen for at least two consecutive years, so water trapped in the soil or rock stays solid over the long term. This term directly captures the idea of ice being within the subsurface rather than as a surface ice body. A glacier or an ice cap, on the other hand, is a large mass of ice on the surface that forms from accumulated snow and can flow or move—it's not the frozen state of the ground itself. Ground ice refers to ice present within the soil, which is part of permafrost, but the broader feature described by “water perpetually frozen in soil or rock” is permafrost. Understanding permafrost is important because it defines the subsurface frozen condition, includes various forms of ice within the ground, and has implications for ground stability and climate-related feedback when it thaws.