Phupa Terb is a series of small to large undulated sandstone mountains eroded by the wind and rain, part of the Mukdaharn National Park. It is at the end of the Phu Pan mountain range. The north–south range runs parallel to the Mekong River. Inside the national park, there are a number of mountains with Phu Jorm Sri, the summit. The forest to be found is mostly dry dipterocarp and mixed deduces types.
At the beginning of winter, around October onwards, Phupa Terb is at its most pleasing since beautiful flowers are in bloom expansively on an inundated stone field. Thus, both the bizarre stone forms and gorgeous blossom plateau can be appreciated. Besides, the waterfall reaches its best with the maximum amount of water spreading all over the cliff. A cool atmosphere and easy walking even quite a far distance, all contribute to the best season for visiting. Unquestionably, the Terb stones are the principle attraction for sightseeing. Walking through the stone field, scattered mysterious stones with shapes of jets, UFO, China roof, crown, crocodile\'s head, and conch are waiting.
The sandstone\'s durability varies according to compaction characteristics Brown sandstone on a level surface mostly consisting of Silica and fragments of rock are durable. The snow-white sandstone on the lower levels is softer due to carbonate formation. The stone at Phupa Terb stone is composed of Soa Bua and Phu Pan sedimentary rock of Korat stone. This Mesozoic era stone is formed by mudstone, sandstone, siltstone, and 200 metre-thick conglomerate. Apart from the attractive Terb stone, Lan Muchalan, an expandable stone field next to Terb stone, is full of tiny grass flowers such as Soi Suwanna, Yat Nam Khang, Naow Duen Ha, Dusita. The middle of Lan is alsoa great tourist spot to see the Mekong River landscape as well.
From Mukdaharn city, take Highway No.2034 (Mukdaharn-Dontan) to Dontan district for about 15 kilometres. From the main road, the entrance to National Park is on the right. Go straight on for 1.5 kilometres on the tarmac road until you reach the park headquarters. Overall, the distance from the city is only 17 kilometres.