cm 0cm 0pt" class=MsoNormal>The grain size analysis is carried out for the representative samples of the ce prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Chengdu clay taken from the Quaternary sections in the Chengdu Plain, ce w:st="on">Sichuance>. The ce w:st="on">Chengduce> clay consists essentially of silty grains of 5 to 50 μm in size, with an average grain diameter of 7.1 to 7.3 φ(i.e., 7.4 to 6.6 μm in size)and also a small amount of more than 63 μm fraction, and in the diagram, tends to display the bimodal patterns of distribution. The grain size parameters, mean square deviation values and kurtosis values for the Chengdu clay are strikingly similar to those of the northern country-region w:st="on">ce w:st="on">Chinace>country-region> loess and Garze loess, but quite different from those of the fluvial deposits. The above-mentioned aspects suggest that the ce w:st="on">Chengduce> clay is a kind of Aeolian soil. According the results of optically stimulated luminescence (OSL), the ce w:st="on">Chengduce> clay from the Chengdu Plain should be originated from the latest glacial sediments in the middle to late stages of the late Pleistocene. The bulk of the ce w:st="on">Chengduce> clay is distal.ce prefix = o ns = "urn:schemas-microsoft-com:office:office" />
