Karst breccia refers to the sedimentary rock formed under specific geological and hydrogeological conditions, which is the “fossil” to record development environment and formation times of karst and becomes the host rocks of several kinds of ore deposit; sometimes, it is related to engineering construction and it has attracted attention of geological research personnel and engineering staff gradually.

The karst breccia in the geopark mainly distributes in stratum of Lower Triassic Zhenning Formation, especially develops the most in the fourth member, and the typical observing points include: Gouyaoyan segment and Dacaokou segment of Qijiehe Gorge, near the entrance of Zhijindong Cave and places surrounding Xiahongyan village.

The rubble component of karst breccia in the geopark is similar to that of surrounding rock, and it is featured by mixture of big and small rocks, no separation, no orientation and overhead structure. The rubbles at the lower part can be connected mutually; near the place close to surrounding rock, the rubbles or rocks still maintain the attitude of original stratum. All these show that the rubbles were formed by accumulation at site due to collapse, therefore, breccia in the geopark belongs to karst collapsed breccia.

The cement of karst breccia is calcite, where no flow mechanical sediment or plenty of iron mud components are discovered. It indicates that the cement is formed in relatively closed hydrological geochemistry system and under the underground water depositional environment with slow flow.
 
Karst breccia at both sides of Dacaokou Gorge