Language: English with a trilingual abstract in English, German, and French
Before the publication of Dreybrodt & Laumanns (2005a), which summarises the exploration conducted between 2000 and 2005, northern Laos was virtually unknown to speleologists. Only a few reconnaissance projects were conducted prior to 2000 in the province of Luang Phrabang. The afore-mentioned publication provided information on 24,3 km of cave passages from 68 caves.
In the framework of the “Northern Lao–European Cave Project” (www.laoscaveproject.de) the investigations were continued in 2006–2008 (Luang Nam Tha and Houaphan provinces) (Dreybrodt & Laumanns 2008). Further findings from 2009–2010 in the Houaphan and Oudomxay provinces were published by Dreybrodt & Laumanns (2010b).
This publication reports on the findings of the year 2011 (Oudomxay and Sayabouli provinces), including the final survey of the 17 150 m long Tham Chom Ong System (Oudomxay). The cave system is the currently 3rd longest cave of Laos as well as the 10th longest cave of Southeast Asia. This report comprises descriptions of 21 caves with 11,696 km of new passages.
Overall, 92 km of cave passages from 196 caves has been surveyed and published to date from northern Laos (excluding Vang Vieng and Kasi).
1. Acknowledgements/Team Members 6
2. Introduction 9
2.1 History of speleological exploration in Laos 9
2.2 Geological overview 12
3. Cave descriptions 15
3.1 General remarks 15
3.2 New caves of the Oudomxay province 17
3.2.1 Area O1: Xai district 17
3.3 The caves of Sayabouli province 24
3.3.1 Area R: Sayabouli district 26
4. Conclusions 41
5. References 42
Caves explored during the 2011 speleological project 51
Photo tables 53
Atlas sheets cave survey Tham Chom Ong System 55
Atlas sheets cave survey Tham Nam Lot 84
Atlas sheets cave survey Tham Pha Khoun Houay 95
Atlas sheets cave survey Tham Phafah 105