Which mechanism causes thermokarst lake formation when permafrost thaws beneath a tundra landscape?

💡 Explanation

When permafrost thaws, subsidence occurs from the reduction in the volume of ice within the frozen ground, leading to ground collapse and the formation of depressions that collect water. Therefore thermokarst lake formation occurs rather than Isostatic rebound, cryoturbation, or eolian deposition which require completely different geomorphological processes.

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