Pingzhi river is the tributary of Hongshui river, consisting of Liming river, Dahong river and Dasai river converging in Shiren village, Fengwu town. The catchment area is 2029.6 km2, traversing the north of Pingguo county. Karst forms around Pingzhi river are typical and complete, engraving a beautiful landscape picture.
崩塌（崩落、垮塌或塌方）是指较陡斜坡上的岩土体在重力作用下突然脱离母体崩落、滚动、堆积在坡脚（或沟谷）的地质现象。此处可见明显的崩塌体，崩塌体中灰岩破碎严重，且灰岩碎块基本被泥土所覆盖，故为一古崩塌体。Collapse refers to the geological phenomenon that rock-soil body on the steep slope abruptly breaks away from the parent rock under the effect of gravity and accumulates at slope toe or cleugh. There can be seen obvious rockfalls in which the limestone broke heavily and limestone fragments were almost covered by soil, so it’s called ancient collapse.
In the early stage, the crust was uplifted, and the fissures in rocks were developed. Groundwater along fissures eroded mountain body, a cave was formed. Then the earth's crust continued to uplift, the groundwater level continuously fell and the cave was exposed to the surface. The front and back parts of the cave were connected, so light can pass the cave. The karst cave is about 30m high and 80m wide, and Pingzhi river passed under it. The fissures in the inner wall were developed, and the stalactites grew along the fissures. It is fairly magnificent and the rock wall is smooth and polished, hence the name Guangyan.
The joints and fissures in the rocks were developed resulted by crustal uplift. Under the effect of exogenic processes like weathering and erosion, the rock mass collapsed. The rock block is located at the outlet of Guangyan light-through cavity and exposed to the water surface in the dry season. It looks like a crocodile that preys on the water, hence the name “crocodile stone”.
光岩滚水坝导流系统是上世纪50年代的水利工程遗产，体现了早期劳动人民的勤劳与智慧。滚水坝亦称溢流坝，是一种高度较低的拦水构筑物，坝体为浆砌石结构，与导水槽同时砌筑，将水位抬高由导流系统将水引至水力发电站。当涨水时，溢出的水则流向下游。The Guangyan rolling dam diversion system is a water conservancy project heritage in the 1950s, reflecting the hard work and wisdom of the early working people. The rolling dam, also known as the overflow dam, is a low water retaining structure. The dam body is made up of masonry, and it is built at the same time as the gutter. The water level is raised by the diversion system to direct the water to the hydroelectric power station. When the water rises, the overflowing water flows downstream.
The Heiyan light-through cavity is the main traffic artery connecting Fengwu town and Longyan town. At the entrance, there are mainly collapsed deposits covered by chemical sediments, and at the exit, there are many heliotropic stalactites. The secondary chemical deposits such as stalagmites, stone pillars and stalactites growing along the fissures had appeared whitened and blackened. In the cave, there is also a Heiyan monument inscribed with Chinese characters “Zhang Di Ling Yan”, it is a cultural relic under the county level protection.
The heliotropic stalactites are often found at the entrance of the cave with the difference of light and dark light. Due to the attached growth of lower heliotropic organism such as algae, the photosynthesis of the plants absorbs the CO2 in the water drops of the cave top, then stalactites are formed resulted from supersaturated water drops, and grow downward and oblique to the outside of the cave. The stalactite belongs to biological karst form. The stalactites were hung at the exit of the Heiyan light-through cavity and have obvious phototropism.
The rock-soil body on the steep slope or at the top of the cave suddenly broke away from the parent rock under gravity effect, and rolled, accumulated at the foot of the slope or the bottom of the cave to form a loose and porous accumulation body, then the accumulation landscape was formed.
Sinkhole is a near-vertical cave that drains surface water in karst areas and is formed by corrosion, erosion and collapse along the fissures. The semi-circular entrance of the sinkhole faces south-east, is about 50m in diameter and about 40m deep. There are collapse deposits at the entrance. It is the water-removing passage in the wet season.
平治河峡谷即岩溶峡谷，是新构造运动抬升和水流强烈侵蚀、溶蚀和崩塌作用形成的谷地，峡谷长约2.5 km，宽约110 m。峡谷底部为缓缓流淌的平治河，河流受季节影响明显，丰水期时河水深度可达6m，枯水期时则可能会断流。峡谷两侧及河床植被发育，风光秀丽，有白鹭漫步其中，宛若一幅优美的自然画卷。
Pingzhi river canyon is a karst canyon formed by the neotectonic movements like uplift, strong water erosion, dissolution and collapse. The canyon is 2.5 km long and 110 m wide. Pingzhi river flows through the bottom of the canyon. It is affected by the seasons appreciably that it can reach 6m during the wet season while it may be cut off during the dry season. Vegetation on both sides of the canyon and the riverbed is developed, and the scenery is beautiful. There are egrets strolling among the river, just like a beautiful natural picture.
Karst spring is a natural outcrop of underground karst water. Underground water surges upwards under relatively high pressure at the intersection of aquifers or water channels and the ground. The Neimian village karst spring is shaped like an eye, about 20m long, 5m wide and 30m deep. The water is clear, and the spring water surges during the wet seasons.
There are many karst springs within the Pingzhi river subarea, reflecting the water quantity, water quality and kinetic characteristics of underground karst water. Some karst springs have been used as water sources. Banbu spring is a nearly rectangular fissure spring with an area of 30m2, and its water is constantly flowing. The fissures of the surrounding rock are developed. The clean spring water where the fishes and shrimps swims in flows towards east into the underground river.