Doun (Tham) [Ban Ngoy Nua]

DREYBRODT JOERG informations

Frédéric Urien - 23/06/2024

Cave description: Most likely resurgence of Tham Doun Mai Citation: ? Analysis: [4847]: (entrance pic) Entrance clearly visible, 3m high, 15 m wide. It is divided by a rock into two parts. Active river cave with a meandring main passage. A stream exits the cave on river level. During the rain season the Nam Ou floods the cave completeley except the last higher short fossil part. The main passage has a nice mostly 5-10m wide and 6m high rectangular profile. The river bed consists of deposited gravel and clay whereas the ceilling is covered with beautiful dripstones and sinter waterfalls. The passage splits in the middle of the cave and unifies again after 50m. The cave ends after 560m into a sump. The origin of the outflowing water could not be located. A visit during the end of the dry season might be useful to check for a opening. A 110m long side passage diverts before the siphon. It follows straight along a joint with long stalagmites that reach down to the floor. It ends after 100m into a small chamber. This part has an air stream that vanishes in the final chamber and comes probably from above >> survey >> shown on map [5158]: Tham Doun is an active river cave with a meandering main passage that is 5 - 8 m wide and 6 m high on average. The bed of the underground river consists of pebbles, gravel and clay. About 150 m from the entrance the passage splits into wet and dry galleries which soon rejoin. This section of the cave, as well as other parts of Tham Doun, is beautifully decorated with stalactites and flowstone. Approximately 350 m from the entrance of the main gallery, so far running parallel to the Nam Ou, there is a sharp turn to the SW and the cave ends in a sump after 80 more metres. From the sharp turn a narrow fossil rift passage continues straight to the NW for about 150 m. A strong air current in this nicely decorated passage has its origin presumably from the surface above Coordinates: N20° 45' 14,4'' ; E102° 39' 5,4'' >> survey >> shown on map [8525]: only fauna records [expe]: 2012 new position taken, not explored. most likely resurgence of Tham Doun Mai [diary]: Di 24.01.2012 [...] Positions: Ban Sop Jam N 20,77772° E 102,64999° 343m, Tham Han (= Tham Viet) N 20,77653° E 102,65344° 349m, Tham Doun N 20° 75538° E 102,65111° 343m, 2: N 20° 75535° E 102,65109° 341m [...] Equipment: -- During the monsoon season, Tham Doun is completely flooded with the exception of the upper parts of the fossil passage which extend towards the NW [5158] Remarks: References: [4846]: Dreybrodt, J. & Laumanns, M. 2003: Der unbekannte Norden von Laos - Ergebnisse eines Erkundungsprojekts. Mitt. Verb. Dt. Höhlen- und Karstforsch. 49 (2): 38-41. [4847]: Dreybrodt, J. & Laumanns, M. 2003: Northern Laos Christmas 2002. Expedition to Muang Ngoy & Luang Prabang, Lao PDR. Unpublished Report, 20pp. [5158]: Dreybrodt, J. & Laumanns, M. (eds.) 2005: The unknown North of Laos (Karst and Caves of the Provinces Luang Phrabang and Luang Nam Tha). Berliner Höhlenkundliche Berichte 16. 105 pp & Annex. [----]: www.showcaves.com/english/misc/showcaves/Doun.html [8525]: Dreybrodt, J. & Laumanns, M. (eds.) 2010: The Unknown North of Laos (Part 3 - 2009-2010: Karst and Caves of the Provinces Houaphan and Oudomxay). - Berliner Höhlenkundliche Berichte 38. 94 pp + Annex.