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松虎平原系由松滋河、虎渡河冲积而成的泛滥平原,南平～闸口以南为波状平原,虎渡河以东,长江沿岸为宽广的河漫滩平原,迨西有一个以松滋口为顶点的决口扇,扇面向南东缓傾,松滋河河道歧流发育,形成辫状水系。平原区沉积物有冲积和湖积两种成因类型,按沉积物特征大体可以划分为三个带:即滨河床浅滩沉积带、河漫滩沿河沉积带和河漫滩内部沉积带。沉积物粒度由江边向山麓或自缺口扇顶点向前缘变细。湖泊沉积分布在湖泊沿岸由于水浅、汇水面积小,带状分布特征不十分明显。平原沉积物孢粉中既包含寒温带针叶树(松、铁杉、雪松),也有温带夏绿阔叶植物(栎、桦、榆),属暖温带针阔叶混交林,另外,沉积物中含环纹藻、狐尾草等水生植物,以及大量林下水边生长蕨类植物,因此当时可能大部地区为湖沼洼地。
The Plain of Songhu is a flood plains formed by the alluviation of Songzi River and Hudu River. The plain south of Nanping ~ Gate is east of Hudu River, and the Yangtze River is a broad river floodplain plain. Of the sector fan, the fan surface easterly south, Songzi River fluvial development, the formation of braided water system. There are alluvial and lacustrine deposits in the plain area. According to the characteristics of the sediments, they can be divided into three zones: the bank deposits of foreland beds, sedimentary belts along river floodplains and the sedimentary belts of river floodplains. Sediment grain size from the river to the foothills or since the lack of fan tip to the front edge of the thinning. Lake sediment distribution in the lake coast due to shallow water, catchment area is small, zonal distribution is not very obvious. The plains of plains sediments include both temperate coniferous (pine, hemlock, cedar) and temperate summer green broad-leaved plants (oak, birch and elm), which belong to the warm temperate coniferous and broad-leaved mixed forest. In addition, Aquatic algae, foxtail grass and other aquatic plants, and a large number of water plants grow ferns, so most of the time may be lake lakes.