AREA 4: Ban Thong

BT02 Queen’s Cave         Topo (26 kB)

The expedition of 1993 stopped at a depth of -151m, in a small circular passage (conduit forcée (1m diameter)). For thedescription of these parts of the cave, see the 1993 expedition report. The narrow passage is half filled with water and mud; progression is very slow. One duck is rather difficult, one real squeeze takes some time to pass. After 20m of crawling, it becomes bigger and is followed by a pitch of 3.30m (no equipment required). A small passage is followed by a 10.5m pitch. At the bottom there is a chamber, which is large (8 by 2m) compared to the previous passages. A sump full of fish is reached. The total depth of Queen's Cave is 168m, the deepest Vietnamese cave so far. Whilst surveying, the air became contaminated by CO2-gas, which made it hard to get out. When derigging next day, in the meander after the 8m pitch, a two meter snake with a red tail was encountered, sleeping in the narrowest passage, which made us think it would be best to come back a few days later. Local farmers confirmed our decision, it was a ‘very poisonous’ one.

BT09 Som Lu        Topo (25 kB)

From Ban Bo On, follow the path to the north. In the big valley, with two lakes, go Southeast after the first lake. A difficult
climb up to the ridge gives way (small fissure) to a nice, small fossil cave with two chambers. The first is about 25m long
and EW oriented. In the middle, a very beautiful calcite waterfall cuts the chamber into two parts. The roof is a high
fissure with tree roots coming down. Many formations decorate the room. A high fissure brings you to a second chamber,
circular with a diameter of 17m and 10m high. We checked all the holes, but no continuation could be found to this charming little cave.

BT10 Lang Lan 1

From Ban Bo On, follow the path to the north. In the big valley, with two lakes, go Southeast after the first lake. After a difficult climb up to the ridge, turn right. The entrance is located a the base of the steep rock formation. It is a vertical pitch of 22m which is choked. The bottom is dotted with snailshells.

BT11 Lang Lan 2        Topo (23 kB)

The entrance, a large porch, is located about 30m to the Northeast of Lang Lan 1 and 15m higher. Two fossil pitches, connected to each other, can be descended. One stops at 20m, the other one is 31m deep. About 5m above the bottom, a hole gives way to a steep slope of 10m, followed by a beautiful pitch of 22m. The bottom consists of huge unstable blocks, with no opening big enough to go through. This is an obvious example of an earthquake collapse. Going up again we saw a big cave-rat with red eyes. At the top of the 22m pitch we followed a passage upward, which goes in the
direction of the surface. We stopped at a nice stal blockage.

BT12 Hang Nuoc (Military Cave)       Topo (27 kB)

In the village, follow the path past the house of the headman. Behind the lakes turn right. The entrance is fortified with walls. This cave was used as a military depot during the war. The entrance chamber is followed by a large fossil gallery 75m long. This gallery emerges at a river. We followed the river upstream for over 100m; it ends against a boulder. A few side-passages were found but the roof was very low and no draught could be felt. Going back we followed the river. After some low passages we were able to find another entrance. We mapped 250m of development, no further interest.