PART 4.] 
Theobald: Petroleum in Burma. 
121 
bluish clays containing Foraminifera (Triloeulina or some allied form), but few other fossils, 
and evidently an homogeneous deposit formed in still water. The clay has not been pierced 
by the shaft, and, though yielding petroleum, does not appear to be the source or mother bed of 
it. I judge then from the petroleum appearing to line cracks and interstices in the clay 
rather than to be disseminated through it, as may bo seen by fracturing the larger pieces, 
which, though superficially imbued to a small extent, do not seem to be equally permeated 
by it throughout, that it seems probable that the true naphthagenous beds of the group have 
yet to be reached. Into this shaft petroleum trickled at something like two gallons a day, 
till it became filled with water and was abandoned during the monsoon. 
It may at first sight seem a curious thing that no more petroleum escaped into the 
shaft after it had become full of water; but I think a sufficient explanation of this lies in 
the mode of stowage of the petroleum in the rock. The oil occupying minute fissures or 
partmgs in the clay escaped by mere gravitation into the shaft as'long as it was kept clear ; 
but became at once arrested in its course, and, so to say, ponded back when met and opposed 
by the pressure of a column of water of 40 feet. 
I have since heard that the shaft has been re-opened and deepened, and that thereon the 
petroleum recommenced to flow, but the ultimate results of the experiment I am unable at 
present to ascertain. 
The second locality near the village of Bau-byin (Pau-fyeng in map) is situated some 
Bau bjin twelve and a half miles west-north-west from the circuit house at 
Thaiet-mio, and about a mile above the village, which is on the 
banks of the stream, which falls into the Irawadi a little above Thaiet-mio. It is moreover 
distant about four miles north-east of the Pudouk-ben locality, previously noticed in the 
Records for 1870. 
In the neighbourhood are several spots where indications of petroleum occur, all in 
beds of the newer tertiaries and on pretty much the same horizon therein. Bluish shales 
are the predominant beds here, interspersed with sandstones; and fossils are not rare 
throughout of the ordinary aspect of the fossils of this group, sundry species of Arm, 
Pecten, Isocardia, Ostrea, Solen, Cypraa, Conus, Turritella, with crustacean remains 
and shark’s teeth, having been procured by me in the vicinity. 
In the stream about a mile above the village, the blue shales are exposed in a steep 
bluff undercut by the river, and a brown colored patch near the level of the stream indicates 
the extent to which the infiltration of the shales by petroleum has here reached. A little 
below this point a feeble escape of petroleum takes place into the stream from an orifice 
at about its ordinary dry season level. Close to this point a bed of sandstone with a dip 
of 70° south comes in, demonstrating a somewhat abrupt downthrow of the shales, which 
higher up stream are gently undulating, and the presence of this bed has not improbably 
determined the escape of the petroleum at this point, by opposing an obstacle to its upward 
progress, or permeation. 
A shaft was sunk on the precipitous hank of the nulla, and a little petroleum 
obtained from it, but the site was bad, as it is scarcely possible to prevent the stream from 
cutting away the bank and destroying the work. About half way between the banks of the 
stream on the. curve, I recommended a trial shaft should be sunk, the selection being made 
with reference to the position of the presumed extension of the bed of sandstone noticed above, 
which it seemed to me undesirable to try, but beneath which a certain supply of oil may be 
with some confidence looked for. Its escape into the stream, and its diflusion among the 
shales a little higher up the stream, with other indications at no great distance, render a 
