What conditions control the development of caves in Wei Zi?

Wei Zi caves are different from ordinary caves. Weizi Cave is a corridor cave formed by perennial erosion of underground rivers. When the cave was formed, the water source may come from all directions, both surface water and groundwater. Next to Weizi Cave, there is the only Cliff Grottoes in Anhui Province-Wang bridge opening. All the statues in it have no heads, except a slightly larger one with a head. What caused the "headless Buddha" has never been known.