Grain-size Features and Magnetic Susceptibility Characteristic of the SurfaceLayer of the Moraines in the Muztag Ata

Grain size and magnetic susceptibility of 116 samples from moraine soil on the west of the Mustag Ata over 4 000 meters were analyzed.It is found that a main peak occurs at 4~6  in the grain size distribution curves,the mean grain-size ranges between 2  and 6 ,the sort coefficient changes from 1 to 3,and the kurtosis coefficient changes from 1.5 to 3.5.Furthermore,the grain size properties are strongly correlated with the magnetic susceptibility.The grain size characteristics are different with altitude,location and depth of the moraine soil.It is concluded that the grain-size and the magnetic susceptibility of moraine soil on the Mustag Ata are mainly controlled by the soil development, wind and the dry and cold climate under the westerlies.The original moraines lie at 30~55 cm deep below the surface.