The origin and characteristics of Malan loess, Lishi loess and Wucheng loess

1. Loess of Malan, one of the names of the Quaternary loess stages in China. The standard section is located on the northern slope of Zhaitang River in Mentougou District, Beijing. The named section is on the right bank of Qingshui River opposite Zhaitang, Beijing. Secondary terrace. In 1962, Liu Dongsheng, Zhang Zonghu and others, in their study of Quaternary loess, named this type of loess Malan loess after the Malan terraces on the right bank of the nearby Qingshui River. The Malan terrace is 30 to 40 meters above the river surface and is composed of loose loess material, sand and gravel layers, but there is no loess deposit on the Malan terrace.

2. Lishi loess belongs to the late Middle Pleistocene and is distributed in North China, Northwest China, the middle reaches of the Yellow River and other regions. The typical section is in Lishi County, Shanxi, hence the name. It is light reddish yellow, lighter than Wucheng loess and deeper than Malan loess. It is mainly silt sand without bedding. It contains multiple layers of brown-red ancient soil, with many calcareous nodules underneath, sometimes forming layers. Lishi loess is 90-100 meters thick and forms the basis of the Loess Plateau.

3. The Wucheng loess standard site is located on the gravel layer in Liushugou, a tributary of the Xinshui River in Wucheng Town, Xi County, Shanxi Province. It is not in direct contact with the three-toed horse red soil layer. Wucheng loess, the rock is redder in color and contains reddish-brown buried soil layers. In the Wucheng loess, no clear bedding can be seen, and the amount of sand and gravel contained is also small. It is speculated that there was no strong flow of water when it was formed.

Types of loess:

Loess is divided into primary loess and secondary loess.

Primary loess is native, continuously distributed in thick layers, covering low watersheds, slopes, and hills. It is often in unconformable contact with bedrock and has no bedding. It often contains ancient soil layers and calcareous nodules. Layers, vertical joints develop, often forming steep walls.

Loess-like soil is also called secondary loess. It is the original loess layer that is transported by forces other than wind. It is mainly caused by alluvial, slope, and alluvial deposits. It is accumulated at the front of the alluvial fan. Low terraces and On the alluvial plain, there are beddings, rarely intercalated with ancient soil, vertical joints are not developed, and it is difficult to form steep walls.

Reference for the above content? Baidu Encyclopedia - Loess, Baidu Encyclopedia - Lishi Loess, Baidu Encyclopedia - Malan Loess, Baidu Encyclopedia - Wucheng Loess