Final Answer:
The near-surface layer that thaws in the summer is known as the "active layer."
Step-by-step explanation:
The term "active layer" refers to the uppermost portion of the that undergoes seasonal thawing during the warmer months. Here's a detailed breakdown:
Near-Surface Layer: The active layer is situated close to the Earth's surface, typically within the top few meters. It is the uppermost layer of that experiences temperature variations, leading to thawing during the summer.
Thaws in the Summer: The active layer thaws in response to seasonal temperature changes, particularly during the summer months when temperatures rise. This thawing allows for increased biological activity and the circulation of water within the soil.