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黄河阶地的黄土为浅灰黄色沉积物,具有发育良好的棱柱状结构,是松散的高孔隙性的粉砂岩。 1977年8月从河南省孟县附近黄河冲积阶地取了两个样品。第一个样品取自高出泛滥平原约100米的最高一级(第4级)阶地地表下约3米处。第二个样品是从阶地2地面下约15米处取来的。同时从黄河河床干处取了一个样品。对这些样品作了颗粒大小、显微组构、粘土矿物学和固结特性的实验分析。颗粒级配曲线(图1)与龚、常二位发表(1977)的山西西部黄土的一般曲线相似,不过平均粒径要细些。黄河冲积物的平均粒径最粗,分选不良。然而,比起分选极差的黄土样品来,它受到相当好的分选。山西西部黄土受到的分选界于上两者之间,只比黄河冲积物的分选稍差一些。所有样品都明显地偏向细颗粒一端。阶地2样品中粘粒百分数(24%)
The loess of the Yellow River terrace is a light grayish yellow sediment with a well-developed prism-like structure that is loose, highly porous siltstone. In August 1977, two samples were taken from the alluvial terraces of the Yellow River in Meng County, Henan Province. The first sample was taken about 3 meters below the subsurface of the highest level (level 4) terrace about 100 meters above the flood plains. The second sample was taken about 15 meters below terrace 2. At the same time from the Yellow River dry area took a sample. Experimental, particle size, microstructure, clay mineralogy, and consolidation properties of these samples were analyzed. The particle gradation curve (Fig. 1) is similar to the general curve of western Shanxi loess published by Gong and Chang (1977), but the average particle size should be smaller. The average diameter of the Yellow River alluvial coarsest, poor sorting. However, it is rather well sorted out of the poorly sorted loess samples. The classification of loess in western Shanxi is only slightly worse than the sorting of the Yellow River alluvium. All samples are clearly biased towards the fine particle end. The percentage of clay in terrace 2 samples (24%)