The loess plateau consists of a thick layer of wind-blown deposit,
several hundred meters deep, formed during the last
ice age when precipitation was nearly absent.
Before water erosion started to take its toll,
it was a flat land as shown here on the top picture.
Erosion proceeds when a slight slope in the terrain is created
channeling running water to scour into the soil, and
magnifies as the gradient increases, so much so that
sharp drops at the edges of the flat ground are formed,
which gradually converge to reduce the flat top to ridges
(middle picture), and then to mounds (bottom picture).
The flat form is called yuan 塬
The ridge form is called liang 梁
The mound is called mao 峁
Erosion further reduces mounds to take the shape of stalagmites
酷似 桂林 山水 的 黄土 峰林
图片资料: 黄河水利委员会 编:《黄河风》, 黄河水利出版社, 1996.
