YENANGYOUNG. 



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fold, but opening in exactly the opposite direction, The following 

 diagram will demonstrate this sort of structure. 



Fig. 8. Diagram showing arrangement of the intersecting folds in the Kodouno 

 petroliferous tract. 



The line marked (a) would represent a zig-zag ridge, runnino- 

 exactly as the oil belt does, sending off lateral branches (5) separated 

 by hollows B. 



Let us for the moment disregard the question of the origin of 

 such a peculiar structure, which will be dealt with later on and, as- 

 suming it to exist, I shall have to endeavour to show that this structure 

 originated at the time of deposit of the petroliferous strata, which 

 view I trust I shall be able to prove. 



As regards the physical conditions of the folds it is by no 

 means necessary that the crest of the central ridge should retain 

 the same level throughout, in fact it is most probable that it would 

 not, and that its height would vary ; at the same time it is by no means 

 necessary that the lateral branches (b) should all be of the same 

 length, they will probably vary very much, and it is also very probable 

 that they eventually flattened out and entirely disappeared. 



Now let us consider the nature of the deposits formed under the 

 above conditions; it is very probable that these may have been 

 entirely different on both sides, on one side sandy beds were depo= 

 sited, while on the other argillaceous beds were formed ; at the same 

 time owing to the oscillation of the central crest a communication 



( H7 ) 



