Karst features and the controlling factors of redbeds in South Guangxi

The redbed karst morphs in southern Guangxi mainly include gentle hills, underground caverns, karst springs and subterranean rivers as well as karst windows. In 50m depth range under the ground, the caves are mostly non-filled cave of 0.5 to 3m high and the number of caves decrease with depth. The types of karst springs include rising spring and descending spring with big variation in spring flow. There is no subterranean river being found in the aquifers formed only with the redbed yet. The development and the morph features of the redbed karst in south Guangxi are related to lithology and geo-structure as well hydrogeologic conditions. The redbed karst in the area mainly develops in the calcareous conglomerate that formed on the margin of the redbed basin. The group structure of redbeds can be divided into single-bed and inter-bed type. The karst develops stronger in the single-bed type but the karst develops along bedding plane in inter-bed type. Usually ,the redbed caves is more developed near the contact zone of soluble rock and non-soluble rock layers; the redbed karst is much stronger and the cave is bigger near the fracture zone of fault or valley.