A permanently frozen layer of earth. It never thaws out.
It is known as the permafrost.
it is called permafrost
The permanently frozen layer of earth is called 'permafrost'. Please ensure you use a current referent when describing permafrost extent, since permafrost borders are rapidly changing in both directions.
Tundra
permafrost
Permafrost.
permafrost
Tundra
Permafrost.
Permafrost
Permafrost.
That's called the 'permafrost'.