Typical late stage karst landforms in the east of Cao Bang Geopark (Quang Uyen, Trung Khanh, Phuc Hoa and Ha Lang districts)

Tuesday - 09/04/2019 16:40
In addition to the above described cave and lake systems, Cao Bang is famous for mature and old karst landscape with towers rising on large and flat karst fields on open and extended valleys. This landscape can be observed in many locations in the districts of Trung Khanh, Quang Uyen and Phuc Hoa etc.

Starting from Ma Phuc Pass at the Cao Bang-Tien Yen fault, the eastern part of Cao Bang Geopark, including Quang Uyen, Trung Khanh, Phuc Hoa and Ha Lang districts, belongs to another, so-called Quang Hoa karst plateau. Its height decreases from above 800m east of Ma Phuc Pass to 400-600m toward the east and the south. This is a typical old karst area, with remnants of karst towers rising up over a terra-rosa bed on the flat-bottom; inter-connected valleys at some places a few hundred meters to nearly 1km wide and tens of kilometers long, now occupied by rice and sugarcane fields.

Other areas such as Quoc Dan and Tu Do communes, the valleys and karst fields are interconnected towards the north-east-Southwest and sub-longitude directions, which created rice and sugarcan fields with more than 10km long. South of Quang Hoa plateau, the valley floors are at an altitude of only 390-470m asl, so underground streams emerge from cave passages, watering rice, corn and vegetable fields nearby. Between valleys and fields are karst blocks in the form of truncated pyramids, cones or other bizarre shapes, up 700-800m high.

Located at 600m asl at the foot of a 200m-high cliff, Ma Phuc Pass follows a NW-SE trending fault, connecting the karst-tectonic valleys along the fault. There are outcrops of pillow basalt at the base of cliff - an expression of lateral rifting. In between the exposures of Carboniferous-Permian limestone are small limestone outcrops of the Na Quan formation (D1-D2enq) and terrigenous rocks of the Song Hien Formation (T1sh).

Source: Ngọc An

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