Thach Dong is a small and isolated limestone mountain located in Ha Tien province, beside the southwest border of Vietnam and Cambodia, bringing geological evidence and deserves to be considered a famous heritage of Geomark which tourists should not ignored.
Location of Thach Dong
Thach Dong (located in My Duc commune, town of Ha Tien, Kien Giang Province) is the steep limestone mountain as a tower, about 45 meters in diameter of the mountain foot but it is 93 m high above the sea level.
From the center of Ha Tien town, you go on the paved national highway 80 toward Xa Xia border gate on the Cambodian border about 3 km, you will see Thach Dong Cave Pagoda is located on the side of the road.
Characteristics and the mysterious story of Thach Dong Cave
The first geological heritage of Thach Dong should be mentioned: the fantasy cave system inside the rock tower, with many shaped fancy stalactites. This is also the place emanating Thach Sanh fairy tale. In this story, Thach Dong Cave was the cave of eagle. The cave has the way deeply underground and getting through to the sea, where Thach Sanh passed to meet Thuy Te king.
Thach Dong cave also has natural air hole making the light in Thach Dong become fanciful. You can go up a small ladder to the second floor to look outside the cave, having a stalactite with the head shape of a giant eagle catching a girl.
Inside Thach Dong, there is Tien Son Pagoda was built in 1790 around the time when Mac Thien Tich was a General of Ha Tien town by Rinzai Zen with the 41st generation. Historical sources said that: before the pagoda was built, this is the hermitage of Taoist Huynh Phong Chan Nhan (after that, he followed Buddhism, so his name changed to Huynh Phong Hoa Thuong) Mac Cuu period, the father of Mac Thien Tich. Since 2003, the main hall was rebuilt; the floor was paved with the marble.
So, Thach Dong Mountain essentially is a hollow limestone blocks. At dawn, white clouds threaded through dynamically create a bizarre picture called “Thach Dong Thon Van” – meaning the rook cave swallow clouds – one of 10 beauty spots of Ha Tien province.
Geological information of the cave
Limestone in Thach Dong was determined by the geologists formed in the Permian, about 250 million years ago. These limestone were mainly derived chemical sediments, they were not biological sedimentary rocks such as limestone of the same age in the north of Vietnam.
Thach Dong-style limestone are common in coastal areas in Kien Luong District, and spreading to the southwest of Cambodia and the south of Thailand, that is located entirely on the west-south faulting Hau River. In the 1980s, Thailand geologists have found many fossil of Hand roll animals (Brachiopoda) of Permian age in the limestones as the limestone in Thach Dong, also located in the southwestern part of extended Hau River fault system (Thailand called faulting Maeping, stretching up into Shan state of the Burmese).
The analytical results showed that: this is the group of Hand roll animals in cold water coil native Australia. Geologists of French Academy also calculated that in the history, the southwestern part of Hau River Fault (southwestern of the south in Vietnam and the southwestern of Cambodia) moved toward to the southeast about 300 km.
This moving process was caused by the sliding force of Indian subcontinent (also originated from Australia) when moving to the north to form the Indian Ocean. This means that if we move the southwest part of the south of Vietnam along the Hau River fault back to the northwest about 300 km, you can see the rocks of the southwest part of the south of Vietnam perfectly pairing with the Siem Reap region of Cambodia and Dangrek mountain which is next to Khorat Plateau of Thailand located in the northeastern part of this fault.
Thus, limestone in Thach Dong cave was a witnesses about the history of a great movement of a region drifting from Australia up, and then slided a long distance to the southeast following the Hau River Fault.
It is still a mystery that: why the hollow rock mountain with a lot of cracks – Thach Dong – has existed for millions of years without falling down? It is not any geologic mystery can be answered accurately. Geological heritage attracts tourist is come from geologic mystery. In many years, Thach Dong has been an attractive spot for thousands of tourist visiting each day. Thach Dong is not only the pride of Ha Tien but also the revenues of local communities through tourism activities.