What is the cause of karst landform?

What is the difference between the landforms of Zhangshiyan [2], Danxia and Zhangjiajie? The landform of Zhangshiyan was put forward by Guo Kang, a researcher at the Institute of Geography, Hebei Academy of Sciences, when he made a tourism plan for Zhangshiyan area in the late 1980s. At that time, there was a lot of discussion about the landform of craggy rocks. Some tourists think it's Danxia landform, while others think it's Zhangjiajie landform, so after a detailed investigation and study of Zhangjiajie, craggy rock and this Danxia landform, it is found that it's completely different from those two places.

Zhangjiajie landform is characterized by tower-shaped peak forest, which seems to be a landscape with thousands of peaks and stones.

The red Qifeng rock in Danxia landform is somewhat similar to that of Zhangshi rock, but they are all washed and cut by running water as a whole, with massive structure as the main structure.

However, the craggy rock landform is characterized by continuous long walls, curved valleys and open canyons in Ya Dan. Therefore, it is considered as a new type of landform, and named as Zhangshiyan landform, which ranks alongside Danxia and Zhangjiajie as the three major sandstone landforms in China. This special shape of craggy rock is related to the properties of the rocks that make it up. This hard thick layer is its main component-timely sandstone, under which is a thin and soft mudstone or argillaceous sandstone.

Although thin, it has played a great role in the formation of craggy rock landforms. Because it is soft, it is weathered and denuded first, and then the upper one collapses under the action of gravity. This is one of the main reasons for the formation of craggy rock landforms, and Danxia animation is also a main mechanism. This is different from Danxia landform. Danxia landform is soft in its whole rock stratum, so it sometimes peels off layer by layer from the outside to the inside. This collapses from bottom to top, and then goes backwards. When the soft rock at the bottom is eroded and excavated, the upper rock collapses down along the crack, forming a deep valley with one end open first, and the steep walls at both sides continue to collapse, gradually forming a shaped valley. Of course, the wonders of the world, such as the craggy echo wall, can be said to be unparalleled in the world, so perfect and natural, nor can it be said to be a masterpiece of eternal nature.