Introduction to Dichi: Tianchi, Dichi and Renchi are three karst depressions, and the framing rock layer is argillaceous limestone of the Guniutan Formation of the Ordovician. Affected by geological structures, water erosion, dissolution and other effects, depressions are formed at three steps in the middle of the scenic area. From top to bottom, they are Tianchi, Human Pond and Earth Pond.