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本文研究成果表明: (1)宜昌附近的长江河谷共形成五级阶地。第一级属堆积阶地,组成物质为全新世灰褐色、黄褐色亚粘土、亚砂土和含砂砾石层。其余属基座阶地或石质阶地。基座上的覆盖层,第二、第三级阶地为更新世晚期红黄色、棕黄色亚粘和砾石层,第四、第五级阶地为更新世中期网纹红土和砾石层。第一级阶地因组成物质同新高温时期长江上游的特大洪水在三峡出口造成的局部性加积有关,又属气候阶地。 (2)但是,宜昌以东的古老背只有四级阶地,峡内巫山却有十级。这种阶地级数的不相一致性,同峡内外地壳运动的差异性、侵蚀作用和堆积作用的差别性都有密切的关系。 (3)更新世晚期,长江在三峡出口堆积了宜昌坝和西坝,全新世中期又堆积了大块石垄和葛洲坝,形成特别巨大的呈一字形雁阵式排列的山前冲积扇复合体,把长江分割成大江、二江、三江和四江。四江已成为长江故道。 (4)大块石垄可能是新高温时期长江上游特大洪水来临时峡内某一河段地质地貌条件同时发生突然的大规模的异常变化造成的。 (5)南津关湾道是在特定的水流、边界条件下长江自身河流运动的结果。
The research results show that: (1) The Yangtze River valley near Yichang has formed a total of five terraces. The first stage is accumulation terraces, the composition of material for the Holocene taupe, yellow brown clay, sandy soil and sandy gravel layer. The rest is the base terrace or stony terrace. The cover on the base, the second and third terraces are reddish yellow and brownish sub-viscous and gravel layers in the late Pleistocene. The fourth and fifth terraces are reticulated lateritic and gravel layers in the mid-Pleistocene. The terraces of the first terrace are also climate terrains, which are related to the local accumulation caused by the extra-large flood in the upper reaches of the Yangtze River during the high-temperature period and the export caused by the Three Gorges. (2) However, there are only four terraces in the ancient dynasty to the east of Yichang, while there are ten levels in Wushan in the gorge. The inconsistency of this series of terrains is closely related to the differences in crustal movement both within and outside the gorges and the differences between erosion and accumulation. (3) In the late Pleistocene, the Yangtze River deposited Yichangba and Xiba at the mouth of the Three Gorges. In the mid-Holocene, large-sized ridged ridges and Gezhouba were also accumulated to form a huge piedmont alluvial fan complex arranged in a zigzag geese formation. Divide the Yangtze River into two rivers, two rivers, three rivers and four rivers. Four rivers have become the old course of the Yangtze River. (4) Large stone ridges may be caused by sudden large-scale anomalous changes in the geological and geomorphological conditions in a certain section of the Yangtze River during the flood season in the upper reaches of the Yangtze River at the high temperature. (5) The Nanjingguan Bay Road is the result of the Yangtze River’s own river movement under specific water flow and boundary conditions.