Recorch of the Geological Survey of hidin. [toi.. Xi, 
within banks, which they seem to have raised themselves, and having a concave 
surface in their cross section ; the sides, which necessarily cooled sooner than the 
central part, preserving their thickness, and taking the form of high banks or 
ridges, between which the internal lava-stream flowed on for some time, as in 
a canal, the level of its surface gradually lowering as the supply fi-om above 
ceased.”^ 
The sources of the mud are undoubtedly the gray shales which form such 
an important part of the rocks throughout the islands. Although these are 
generally brittle and clnnehy in a dry state, when thoroughly soaked with water, 
as they are seen, for instance, along the shore at low tide, they break with a some¬ 
what plastic mode of fracture, and are easily kneaded into mud identical in 
appearance with that ejected from the volcanoes. 
I have not myself observed the mud to possess any sensible degi’ee of 
w'armth, but I was not fortunate enough to witness any actual eruption beyond 
a mere dribble. That the mud is waiun, however, at times, wo have the evidence 
of Mr. Howe, who found “ a hot slimy fluid” some time after a fiery eruption 
from one of the Kyauk Phjm volcanoes. Captain Halsted found mud brought 
up from a depth of 17 feet at one of the Ramri volcanoes to slioiv “a temper¬ 
ature of 92° 20', above that of the atmosphere” {sic; misprint for 92“, 20° above 
that of the atmosphere ?). Hr. Spry also remarked that the crater of one of the 
,Kyauk Phyu volcanoes, 12 feet in diameter, “ was filled with warm liquid mud.” 
The ejected mud alw'ays contains more or less saline matter, which is princi¬ 
pally common salt. Occasionally, ho wever, this .salt is mixed with a large propor¬ 
tion of sodium sulphate, and contains calcium sulphate besides. It has been 
suggested that the salt is derived direct from sea water,- and Captain Williams 
even mentions having received a fish which was said by the natives to have 
been thrown up by one of the Kyauk Phyu volcanoes.^ This idea, however, is 
scarcely supported by the want of uniformity in the compo.sition of the salt, and 
it is, I think, probable that the latter is derived in considerable part from the rocks 
themselves that yield the supply of mud. The intimate connection between the 
petroleum and mud volcanoes of Ramri will be subsequently alluded to, and it is 
well known how frequently mineral oil and salt are associated. In India they 
are found together in the oil-producing tracts of Burma, Assam, and the 
Punjab.^ That the Ramri rocks do contain saline matter I found by examining 
the shales or clays from the oil-wells of Tsi Chang, Letaung, and Minbain, which 
when lixiviated with water all yielded soluble chlorides and sulphates in varying 
proportions. Further, it appears from Dr. Oldham’s account that the mud from the 
craters at Menbo on the Irrawadi, .some 70 miles from the sea in a straight line, 
is saline also, and is largely used for the preparation of salt by lixiviation. 
Water in considerable quantity' is, of course, a necessity for the production 
of the often slushy mud ejected by the Ramri salses, and that this in some 
' Volcanoes, p. 76. 
2 Trans. Bombay Geol. Soc., X, 146. 
^ Journ. As. Soc„ Bengal, XII, 334. 
■* Rec. G. S. I., VI, 70: Mem. G. S. 1., XII, 356 ; XI. 129. 
