One hauled it open, and she peered into the impenetrable depths.
The whole is clothed with impenetrable forest.
In height, is predominant, and on account of the dense undergrowth chiefly of ferns and climbing vines, forms the most impenetrable of the forests; its hard wood is used chiefly for fuel.
Pomerania, protected on the south by virgin forests and almost impenetrable morasses, was in those days inhabited by a valiant and savage Slavonic race akin to the Wends, who clung to paganism with unconquerable obstinacy.
A waterlogged soil is impenetrable by air, and owing to the continuous process of evaporation and radiation, its temperature is much below that of drained soil.