Double mountain under the type of tectonic – Geomorphic heritage, located in Tam Son town, Quan Ba district, Ha Giang province. It is 47 kilometre from Ha Giang town. Situated at an altitude of over 1000 meters above sea level, fresh air, wild scenery, majestic nature with endnessly range of Limestone Mountains. The nature has granted here a wonderful place called “Co Tien double mountain”, it is two tops of the limestone mountain. Its shape is the same as “two breasts” of the girl, lie in the middle of the field in Quan Ba. This actually is an unique landscape of Tam Son in particular and Dong Van karst plateau Geopark in general.
“Co Tien double Mountain” is truly product of the process of leaching, erosion with regular practice in the destruction of the fault zone in Quan Ba- Huong Cha that its last phase of activity occurred about 5 million years ago. In fact that, there are many karst scene in the valley of Quan Ba, only “Co Tien double mountain” is the most beautiful and located at the most favourable position to visitors can see.