AREA 6: Ban Phe

BP06 Noong Xom

Before the village of Ban Cieng Puoc, leave the road to Dien Bien at the cement factory and follow the valley up to the polje. After going 200m north, the cave lies on the right side. After the entrance chamber, a meander leads into the side of the valley, and can be followed Southeast. The cave goes slightly uphill, narrows, and has some formations here and there. A cleared blockage gave way to a few more meters to where the passage became too narrow. This cave used to drain water from the hills to the valley, but recently became inactive. The actual outlet might be found on a lower level.

BP07 No Name

This cave has a beautiful entrance, and is well known by the local people. It is located in a large doline, into which a little stream flows. One side of this beautifully overgrown doline is very steep. It is in this part that the large entrance opens into the cave. An inclined gallery can be followed over large blocks and small cascades. The gallery ends in a sump, which can be bypassed on the right side, but is immediately followed by a second sump.

BP08 Tham Huoi Tap

Coming from Ban Lay, before the valley to Ban Vay, there is another valley going Southeast. At the end one finds an artificial lake, used for the irrigation of the rice fields. The entrance of the cave lies on the Southeast side, about 40m above the lake. A short pitch leads into a canyon, which was dry at that time, but the sedimentation shows that this is an important drain during the rainy season (the villagers spoke about a roaring sound). Upstream the canyon soon ends; it heads to the lake, but a passage was not found. Upstream the aspect of the cave changes; the canyon turns into a narrowing gallery, sometimes interrupted by small, beautiful chambers, which goes slightly downhill. The bottom is covered by mud, sand and some boulders. At the end, the gallery becomes impenetrable. The cave drains the water from the hill to the valley (into the lake).

BP12 Water Cave

Just after the village of Ban Vay, next to the road, there's a resurgence, being used as washing place. The audience at the entrance of the caveThe entrance of the cave is magnificent; the water is blue-green, and from the inside, one can see the different entrances which light the lake. After the lake, a meander is filled with water and requires swimming in most parts (neoprene and life-jacket recommended). Close to the end of the cave there are cascades in two shallow parts and a chamber with collapsed boulders. The cave ends in a sump, where the gallery descends steeply. A side gallery can be followed, which ascends, but soon becomes impenetrable. This active cave has an important discharge and drains the hills of the area in the southern part of the valley.

BP13 Tham Han

After a long search for an entrance to the underground Nam Muong system, we finally found an access, about 15m above the valley bottom, where a strong, hot, wet draft could be felt. There was no doubt about the connection to the underground river. After descending 10m without equipment, a dry room was reached, where continuation was found easily because of the strong draft. A small inclined passage between formations gives way to a large dry room. The floor consists of huge blocks, under which one can hear an inlet of the high-volume river. Going down the room we reached the inlet, but the room continues over 50 m, 10m above the inlet. The room turns 80° to the NE, and 50m farther the river comes in. Several inlets come together and form a river with a huge discharge. The river was followed North over 200m in a beautiful active joint with steep walls. A part of the river disappears in a small fissure that becomes too narrow. To the left a horizontal fissure goes to the east and after 50m the river is reached again. Here one can observe interesting erosional phenomena, like solution pockets more than 1m in diameter and depth. The waterfall of Tham HanThe ceiling became low and we abandoned the river again. Approximately 40m further, the river is met again by climbing down 4m. The cave becomes larger again. At the left side a 10m waterfall comes in. A spectacular descent near the waterfall became too dangerous. The wild river was followed about 10m higher in a horizontal fissure, where we went down to the river in a joint (P10). Here, it disappears in another fissure, which becomes narrow and choked with blocks. Up high we found a route behind a boulder, and 50m farther, after a descent, the river was found again. The gallery is big and the ceiling is high at "Terminal Lake" where the river gets up to 25m wide. About 60m further the ceiling comes down along a bedding plane. In a small tube a siphon was found (no continuation without diving gear).
On our way back, a large sleeping snake was encountered. The hydrology of the system is quite different from what we expected from the topographic map. Only a little part of the incoming water is emerging to the north. Indeed the discharge to the north is small with respect to the sink, a dye trace will be needed. The cave turns to the east, into the mountain. We searched for several days for an entrance to Tham Han behind the sump. We believe Co Phai is a cave connected to the underground system.

BP14 Tham Met

Follow the big path from Ban Thum to the north. Over the hill take a little path to the left next to a huge doline. About 150m further there is a big entrance, 10m high and 30m wide. It is a big room, 20m deep, 40m wide, and 10m high. The floor consists of blocks, with white formations.

BP16 Po Badin

We found this interesting cave while looking for an entrance to the underground river of Tham Han. Above the resurgence of Tham Han take the path to the right. The cave opens at the bottom of the second huge doline. The entrance follows the bedding plane, dipping 50° to the south over 45m. It is followed by a vertical pitch of 15m ending on a platform. A small hole leads to a 30m pit. We realised that we were at the ceiling of a huge dry room (about 150m long, 50m wide). In the room we recognised the bedding of an abandoned river. The river disappears into a muddy hole. Many old formations could be found, covered with dry mud (guano?). At the east side a small hole between formations was widened and a second chamber (30 m) was entered, where a thick layer of guano covered the floor. First we thought that we heard the sound of a river, but the noise was produced by thousands of bats at the ceiling. At the north side a fossil inlet could be followed over 40m, through the guano.

BP17 Huoi Nam Un 1

The entrance of the cave is located at about 200m downstream of the probable resurgence of the Nam Muong river. Here, the river disappears again. The entrance was found earlier, but was not entered because the farmer told us the river flows just a few meters below the rice field and resurges 200m farther...The entrance is 2m by 2m into which a river disappears. The water is followed between trunks, a system of 14m is reached. In a room two routes can be followed, the first is an inclined plane with a pitch of 5m in a waterfall. In a little room the passage turns 90° to the East, and some nice lakes with flowstone lead to a siphon lake, which is beautifully decorated. The other passage is a conduit that follows the bedding plane. After climbing down waterfalls of a few meters, with deep circular lakes, a siphon is reached, but 30m back at the ceiling is a gallery which passes the siphon. We continued about 40m more until a second sump was reached. There might be a possibility of diving. As the water levels of the sumps are at the same height, we think we reached the level of the water table.

BP19 Resurgence

At this point the water of the Tham Han valley exits again. It can be reached by climbing down a canyon. On the way, one can see that the karst stops and is replaced by schist. The discharge of this river is much larger than that of the river which disappears in Tham Han. The strange thing is that the water seems to come from the Northwest, which means that the water should make a sharp turn, at the contact with the schist, to the Northwest, to resurge here, probably via another cave that drains the north-western highland.

BPxx Co Phai

We found this cave while looking for an entrance to the underground Nam Muong river. At the bottom of a doline, between blocks, a small fissure goes down 10m at 60°. A squeeze was widened and a few meters farther we passed another squeeze. After descending a few meters we entered a small room, where a big boulder obstructs the way. A very strong, wet and hot draft could be felt, making us believe that the cave is connected with the underground Nam Moung river system. However, it will take several visits to clear the obstruction, which might be interesting for the next expedition.

BP 20 Hau Lay

No description available yet.

BP 21 Hang Bun

Location: First wide doline at the right when descending into the valley.
In the doline there are 2 entrances. One of them is an evident sloping P13 that emerges into a chamber and leads to the downstream part. A second entrance through the blocks leads to the upstream part. A minor desobstruction down the P13 was needed to connect the two parts. Downstream after a few tens of meters an effluent enters the cave and it leads to a nearby doline, through a clear fault. A traverse is possible. Upstream small galleries (fracture) are alternated with wider chambers with formations and low passages. The chambers and some flat passages contain quite a lot of mud (muddy mountain), not yet fully dried up. The passage is interrupted by three dry V-shaped siphons. A thick layer of pebbles follows each of the siphons. The third siphon was completely dug out of the pebbles. Despite of the strong draft we were bothered by a high CO2 percentage. After a long narrow fracture we got to a larger part with soft mud. From a hole in the mud (50 by 50cm and probably again a dry siphon) comes a strong draft. The hole has not been checked because it seemed too muddy.