Phong Nha - Ke bang national park
Located 50 km in the northwest of Dong Hoi Township; the 41.000 ha Phong Nha – Ke Bang Natural Reserve belongs to Bo Trach District; Quang binh Province. The system boasts various kinds of animals and plants which are listed in the Red Book of Vietnam. Especially; three new species of big animals in the world have been discovered recently here namely the mang lon (big muntjak; meganumtiacus vounanoensis); the sao la (a kind of wild buffalo; pseudoryx nghetinhcusis) and the mang Truong Son (Truong Son muntjak).
In the reserve 30 grottoes and caves have been discovered which were formed in the course of hercynian folding movements (mountain building) 300 millions years ago. Especially; the 7.729m long Phong Nha is praised by the international community as a grotto having seven superiorities in comparison with others of the world: the longest grotto; the highest and largest vault; the most beautiful underground lakes; the driest and biggest caves; the most beautiful and imposing stalagmites and stalactites; the longest underground river; the largest; nicest rocky and sand grounds. .
The karst formation of Phong Nha-Ke Bang National Park has evolved since the Palaeozoic (some 400 million years ago) and so is the oldest major karst area in Asia. Subject to massive tectonic changes, the park’s karst landscape is extremely complex with many geomorphic features of considerable significance. The vast area, extending to the border of the Lao People’s Democratic Republic, contains spectacular formations including 65 km of caves and underground rivers.
Phong Nha is part of a larger dissected plateau, which also encompasses the Ke Bang and Hin Namno karsts. The limestone is not continuous and demonstrates complex interbedding with shales and sandstones. This, together with the capping of schists and apparent granites has led to a particularly distinctive topography.
The caves demonstrate discrete episodic sequences of events, leaving behind various levels of fossil passages, formerly buried and now uncovered palaeokarst (karst from previous, perhaps very ancient, periods of solution); evidence of major changes in the routes of underground rivers; changes in the solutional regime; deposition and later re-solution of giant speleothems and unusual features such as sub-aerial stromatolites. The location and form of the caves suggests that they might owe much of their size and morphology to some as yet undetermined implications of the schists and granites which overlay the limestone. On the surface, there is a striking series of landscapes, ranging from deeply dissected ranges and plateaux to an immense polje. There is evidence of at least one period of hydrothermal activity in the evolution of this ancient mature karst system. The plateau is probably one of the finest and most distinctive examples of a complex karst landform in SE Asia.
In summary, Phong Nha displays an impressive amount of evidence of earth’s history. It is a site of very great importance for increasing our understanding of the geologic, geomorphic and geo-chronological history of the region.