Introduction to Vicissitudes Rock Arch: An "anticline structure" formed by the Permian Maokou Formation limestone formed about 250 to 295 million years ago. After subsequent tectonic movements, it underwent strong bending deformation and folding. Compared with the huge power formed by the vicissitudes of rock formations, the largest earthquakes recorded by humans in the world are just a piece of cake, which is evident from the formation of this kind of landscape.