Phong Nha-Ke Bang area is noted for its cave and grotto systems as it is composed of 300 caves and grottos, divided into three main systems: Phong Nha Grottos, Vom Caves, and Ruc Mon Caves.

Phong Nha - Ke Bang can be compared to a huge geological museum thanks to its complicated geological structure with different categories of stone including sandstone, quartz, schist, siliceous limestone, granite, granodiorite, diorite, applet, pegmatite, etc.

Phong Nha-Ke Bang is the oldest and largest tropical karts formed 400 million years during the main geological periods of the Earth, bearing the original topographic and geologic characteristics.

Experiencing major tectonic phases, high mountain ranges and the depressed sedimentary basins were formed. These fluctuations have also contributed to the diversity of geology, topography, and geomorphology.

Phong Nha - Ke Bang karsts mountains can provide a lot of valuable information about the Earth's prolonged geological process through various periods, from the Paleozoic (about 400 million year ago) to the Carboniferous and Permian (340-240 million years ago).

It is also noteworthy to mention a geological characteristic – the system of underground rivers and grottos in limestone mountains.

In the non-karst geomorphologic area, there are many low mountains covered by a floristic carpet. The erosion has created a number of abrasion-accumulation terraces along the valleys of the Son and Chay rivers and at the margins of the central limestone massifs.

The transition terrain consists of a diversity of rock intercalated by limestone mountains.

Locating in the area with a high average rainfall, however, few rivers and streams can be seen because water is absorbed to run inside limestone mountains. Therefore over tens of million years, water has eroded rocks, creating numerous caves in the area.

Exploring beauty of Phong Nha Grotto, the Heritage magazine held a photo tour for photographers to shoot primitive beauty inside Phong Nha grotto at the end of May. The mysterious and majestic landscapes by nature lures the hearts of photographers. The images of Phong Nha Grotto through photos make people feel surprising.

Going by boat about over 1km, starting to explore cavern system to trans-mountain

In the dark, the lights from torches make the cave become sparkling and mysterious

By Nhu Y
(Source: VOV.VN)