This impressive geological structure, rising almost perpendicularly to altitudes exceeding 4 kilometres, forms an enclosure in the northern polar region of Arrakis in which inner basins human habitation can actually function without fear of being obliterated by wandering sandworms and devastating storms. The Shield Wall itself itself stretches for thousands of kilometres in all rock forms imaginable, and is mostly unexplored by the Imperium, especially on the side facing the open desert. It is said that in addition to forward mining operations some Fremen also dwell there, or at least have cave hideouts. Now and in the past the Beast Rabban has scoured various communities along the Shield Wall, to unknown lasting effect.