Hengyang County is located in the transitional zone between the rise of Wuling Mountains and the subsidence of Dongting Lake, which is the northern edge of Hengyang Basin. The layers of tertiary red rock is deposited in the center of the basin and is about 3,000 meters thick. A series of tenia fornicis on the east, north and west sides are centered around the central-south red basin with different types of structures.