system
Given the following post, respond as if you're commenting on Reddit:
human
[Dune] How deep is the sand in the great deserts on Arrakis?

Im thinking it must very deep in order to allow the largest sandworms to move through without massively disturbing the surface. 

What prevents it from solidifying into sandstone?
gpt
Lack of moisture is what keeps sandstone from forming, you have to be able to acquire water then hold it in some fashion below the surface for long periods of time. 

As for the depth? Who knows, Up to a mile, two or more with any rocks above the surface being equivalent to tall mountains in seas of sand.