Abstract: Sand and dust are both products of physical weathering.However, their behaviors are entirely different in the eolian transport process.A rigorous physical test performed by Bagnold proved that dust can fly up to 3000 m high over great distances with wind, while sand grains can move at most by means of saltation near the land surface.All the so-called "sand-dust storms" that attack the North China plain from the north are essentially dust storms.Analysis of sediments deposited in various major weather events also confirms the conclusion.Therefore the sources of dust storm materials are not areas with sand but areas with dust.This study may help people take correct methods for remediation of effects of dust storms.