Berliner Höhlenkundliche Berichte, Volume 16: The Unknown North of Laos

Northern Laos is virtually unknown to speleology. Only a few reconnaissance projects and three caving expeditions were conducted prior to 2005 in the province of Luang Phrabang: a Dutch expedition (AMIS Laos expedition 2000, with a preparatory trip in 1999) and two German projects in 2002 and 2003/04.

The 2000 AMIS Laos project produced approximately 7300 m of surveyed passage from 15 caves, including the 2070 m long system Tham Khan–Pageo (Muang Ngoy, Nam Ou Valley, Ngoy district — now open to tourists), the 1433 m long Tham Gnai (Nan District), and the 1028 m long Tham Pha Kouang (Nong Khiaw, Ngoy district), as well as the deepest cave found to date in the region: the –105 m deep Tham Thia (Nan District).

The two German expeditions produced 5564 m of mapped cave passages from 34 caves, the longest of which was Tham Loum (Xiang Ngeun District) with 1598 m of passage. Finally a joint Dutch–German project was conducted in February 2005. In the area of Phou Khoun south of Luang Phrabang several caves were linked to form a 2,65 km long cave system (Tham Seua–Nam Lot). A new caving region was visited around Vieng Phouka in the Luang Nam Tha province close to the Thai and Burma borders. The first investigations resulted in significant findings such as Tham Pasat (Tham Nam Mai) at 1490 m, Tham Nam Eng (Fossil Cave) at 3120 m, and Tham Nam Eng (Resurgence Cave) at 3460 m.

Overall, roughly 24,3 km of cave passage has been surveyed to date in northern Laos. This report contains an overview of all visited caving regions with detailed maps and cave descriptions. Additionally, one chapter is dedicated to biospeleological investigations.

Abstract / Zusammenfassung / Résumé     5

1     Acknowledgements / Team Meübers     6
2     Introduction     10
2.1     History of speleological exploration of Laos (by J. Dreybrodt & M. Laumanns)     10
2.2     Geological overview (M.Laumanns)     14
3     The caves of the Luang Phrabang province (by J. Burgers, J. Dreybrodt, D. Eskes, M. Laumanns, H. Steiner & W. Zillig)     15
3.1     General remarks     15
3.2     Area A: Nong Khiaw / Muang Ngoy     16
3.3     Area B: Nam Bak     23
3.4     Area C: Ngoy Nua     26
3.5     Area D: Thong–Khang     37
3.6     Area E: Luang     45
3.7     Area F: Xiang Ngeun     59
3.8     Area G: Nam Khan     67
3.9     Area H: Nam Pa     70
3.10     Area I: Phou Khoun     74
4     The caves of the Luang Nam Tha province (by J. Burgers, J. Dreybrodt, M. Laumanns, H. Steiner & W. Zillig)     79
4.1     Area J: Vieng Phouka     79
5     Biospeleological observations     86
5.1     Bats (by Martijn Boonman)     86
5.2     Biospeleological notes on Laos (by Helmut Steiner)     92
6     Conclusions     97
7     References     98

Annexes     
Caves explored during the 2000, 2002, 2003/04 and 2005 speleological projects     103
Photo tables     106
The known caves of northern Laos according to map sheets 1 : 100 000 (by H. Steiner) 116     
Atlas sheets cave survey Tham Nam Eng     120
Atlas sheets cave survey Tham Pasat (Nam Mai)     135
Atlas sheets cave survey Tham Seua — Nam Lot     141