Located in Mengxi Village, Luota Township, Longshan County, Wuyan (Eave) Cave is developed in lump, micritic limestone and bioclastic marl in Qixia Formation（P2q） of the Permian system.
The entrance to the cave lies in the junction between fractures running in the direction of north-northeast and those in the direction of northwest, while its main body is developed along the fracture in the north-northeast direction (Photo 4-97). The entrance to the cave is 46m high and 26m wide , with a strike of 305°, and a direction of 70-80° after 50m. The width of the cave ranges from 5-37m, with an average width of 10-20m. The vertical section of the cave bottom is shaped like a ladder, which is divided into three layers : upper, middle and lower parts. While the middle layer is 10-12m higher than the lower layer, the upper layer is 15m higher than the middle one.
The cave walls in the lower layer are regular and straight, serving as the drainage channel. The cave bottom in the middle layer is over 10m wide, and 10-15m high, with uneven walls and development of branch caves. The cave bottom in the upper layer is 10-25m wide, also with uneven walls and development of small branch caves. Many blue holes and headcuts occur in the cave. While the heacuts are often 5-6m high, the blue holes are 1-7m deep. There are seven large blue holes, which are generally 20m long, 15m wide and 4m deep, with the maximum length of 120m and depth of 6-7m (Figure 4-33). A small amount of speleothems including stalagmite, stone curtain and stalactite, are developed in the cave. The cave body often has a large size. Outside the cave there are some famous scenic spots, such as Luota Platform and Cliffs, and Diaoshuikan Waterfall, which have high values in viewing and popular science education.
Photo 4-97 Entrance to Wuyan Cave
Figure 4-33 Plan and section of Wuyan Cave