114 NOETLING : PETROLEUM IN BURMA. 



stage, which apparently do not reach to the surface, but which 

 must have been formed previous to the deposit of the Yenangyoung 

 stage. These intersecting folds represent the wrinkles on the 

 surface of the mud stream or the folds which must have been 

 produced by the sliding of the masses according to the above 

 theory. Could we ascertain that they were slightly curved, the proof 

 would be conclusive, but the data available for the present are 

 too scanty to prove this. As it is we must rest satisfied that 

 there exist such folds as required by the theory, and we have now to 

 investigate the question whether there is any other additional evidence 

 which supports the theory. Now what stronger proof can there be 

 than the presence of veins filled with eruptive mud and the beds of 

 eruptive mud injected between the other strata as described on 

 page 83. In fact the presence of the mud veins becomes only 

 intelligible in view of the above theory, and their more frequent 

 occurrence in the southern part of the field tends to indicate the 

 region which was under the greatest pressure which therefore 

 was nearest to the termination of the downward movement. 



It is further quite obvious that when a series of beds is simul- 

 taneously moving, and eventually arrested, the single beds must 

 become in some parts compressed and in others stretched or 

 thinned. In other words an individual bed must exhibit a great 

 variation of thickness within a limited horizontal extent. I think 

 that the sections of the deep borings have given ample proof on 

 this point. Although we might explain the reduction of thickness 

 by local erosion, the increased thickness can only be explained by 

 compression. 



We may now even go a step further and suppose that while 

 the above mentioned process was going on, younger beds were 

 deposited on the top of those in motion, a supposition which would 

 result in the most complicated structure of the series. 



It seems almost quite certain that the sliding process was ter- 

 minated before the deposit of the lower beds of the Yenangyoung 

 ( '60 ) 



