7 6 NOETLING: PETROLEUM IN BURMA. 



for is the theory of the intersecting folds, which will be discussed in a 

 subsequent chapter. 



We may now sum up in a few words the facts which have been 

 ascertained with regard to the occurrence of petroleum in the 

 Yenangyoung oil field. These are : — 



1. The petroleum is indigenous to the strata in which it is found. 



2. The petroleum is restricted to the arenaceous beds, and tends 

 to rise within them to the highest points. 



3. Whenever water and petroleum are associated in the same 

 bed, the petroleum generally rests on the water. There seem how- 

 ever to be a few instances, which would point to an exception to this 

 rule, although they are not quite authenticated, and open to doubt. 



4. Throughout the series water and petroleum may occur inde- 

 pendently in different beds, following each other vertically, but in 

 this case they are, with few exceptions, well separated from each other 

 by impermeable beds of clay. 



C. Local subdivision of the lower miocene or Prome stage. — The 

 Prome stage being almost exclusively known from deep borings, 

 it would be rash to attempt any general subdivision of this sequence 

 of beds, which are all so much alike in their lithological characters ; 

 but fortunately we have a horizon, containing some very charac- 

 teristic fossils, among which Anthracotherium silistrense takes the 

 most prominent place. As this species has not yet been discovered 

 in any of the higher beds, it may perhaps be admissible to 

 designate the upper Prome beds as the horizon of Anthracotherium 

 silistrense. 



In going through the boring registers anything like a general 

 subdivision of the beds recorded seems an almost hopeless task. It 

 is impossible to subdivide a series of an approximate thickness of 

 1,100 feet, which consists of nothing but beds of clay and sandstone 

 with no further distinguishing characters. The difficulty is still fur- 

 ther increased by the fact, that the beds composing the petroliferous 



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