The dust chasms or dust basins were a weather phenomenon of Arrakis, produced by geological processes, being subsequently filled with dust. They were a hazard to unwary travelers because the dust had a quicksand-like behavior. The dust packing was so under-dense that tidal motions much like oceanic tides were readily observable (locally called sandtides). In other words the dust exhibits almost negative packing, hence fluid-like behavior; similar situations have rarely been found on any other planet. The sequence of events is as follows: