Published for the Royal Geographical Society by J. Murray,
Text on page 53
THE UPPER MEKONG, SIAM.
except at the south-eastern end, where there is a series of largish cracks, whence smoke and free sulphurous acid rise in small quantities; here the ground is very hot, and 2 feet in the cracks are red hot, and one can light a bamboo at them. There were traces of the action of sulphuretted hydrogen or of carbonic acid, and the crust of sulphur at the openings may be due to the decomposition of the former gas. I could neither hear nor see of there having been any great activity at any time in the past, but the
MOUTH OF NAM SUUNG, ABOVE LOANS PBABANG.
existence of a present dormant volcanic action is evident. Why this vent has occurred in the position it has is not obvious ; there is no apparent line of dislocation, nor has it chosen the valley proper.* In the rains there is, I was told, a good deal of steam rising, as is natural, and more spluttering and activity than we saw. At the northern end there were traces of elephants on the slag (which is everywhere highly coloured from iron chloride) ; they are proverbially afraid of fire, so it may be inferred that the activity is not great. Southward the vent, which from the slag surface to the top of its sides is not more than 30 feet, is advancing, and the blackened stumps of newly fallen trees and bamboo clumps lie about, with marks of recent falls in the bank,
* This valley drains into the Nam Ngum, and so into the Mekong. The big mass of Doi Luang to the south is the division between the Meinam and Mekong drainages here.* This valley drains into the Nam Ngum, and so into the Mekong. The big mass of Doi Luang to the south is the division between the Meinam and Mekong drainages here.