HEGa layer of soil that is always frozen in countries where it is very cold 永久冻土层
Examples from the Corpus
permafrost• Lenses of rather pureice are conceivable, but more likely is a permafrost containing 10 percent to 30 percent ice.• Undulatingcoastalplains and other ungraded lowlands, underlain by permafrost, in summer form some of the tundra's wettest areas.• Water extraction from permafrost by distillation seems rather straightforward.• Very important to know, because suppose you got permafrost under your concreteslab?• Florence in permafrost Cold pinches the hills around Florence.• Most of Mars seems to be covered with a layer of permafrost, kilometers deep in places.• The first option is to extract water from subsurface permafrost and use that water directly in a nuclear or solarsteamrocket.• Fulton lay on the permafrost, miming a cerebralhaemorrhage.