112 NOETLING: PETROLEUM IN BURMA. 



I have further shown that the intersecting folds must have existed 

 before the anticlinal arch was raised. The question to be answered is, 

 therefore, by what hypothesis can we explain the origin of the folds ? 

 I think the theory to be promulgated will explain all the curious fea- 

 tures, but before giving it in detail, it will be necessary to recapi- 

 tulate a few facts. We may take it as proven that the petroliferous 

 beds of the Yenangyoung oil field at least, were deposited near 

 the mouths of a large river, or perhaps in a lagoon, communicating 

 with such a river. The proofs for this view are : — 



(a) The fauna discovered is the petroliferous beds, 

 i (b) The bedding of the strata. 



With regard to the first point, a mixture of terrestrial animals, mostly 

 in rolled fragments, and marine fossils has been found in the petroli- 

 ferous beds. A mixed fauna of this type cannot possibly have been 

 deposited far from the coast, even if we admit that the floating 

 carcases of terrestrial animals have been carried away by the 

 tides, for some distance from the shore. With regard to the second 

 point, I have demonstrated that the stratification of the petrolifer- 

 ous beds exhibits such curious features, that we feel bound to suppose 

 that they were deposited in a water subject to periodical and sudden 

 rises like those of tropical streams of the present day. I have above 

 pointed out that it is only the action of a quickly rising current by 

 which we can explain the local erosion and the subsequent deposi- 

 tion of beds, hereby creating local unconformities. 



I think the above two views do not require any further proofs 

 and, if accepted, the ground is clear for the theory of the origin of the 

 folds. 



Such a phenomenon is in fact represented to some degree by 

 a mud stream running down the slopes of a mud volcano, and 

 it was in fact this observation which first suggested the theory. 

 When the liquid mud has reached the less inclined basis of the 

 mud volcano its speed slackens, until its front has come to a 

 standstill, while the upper masses are still in a downward move- 



( 158 ) 



