YiiNANGYOUNG. 65 



contained in the Prome division, but unless proved by deep borings 

 nothing definite can be said about it. It also seems quite certain 

 that the different petroliferous sands vary greatly in horizontal 

 extension, and that therefore complete sequences of the petroliferous 

 sands are by no means found in every single well. In fact, the 

 irregularity of horizontal extension has been one of the chief 

 difficulties with regard to the correlation of the single beds observed 

 in the different drilled wells. In the following enumeration the 

 petroliferous sands are numbered in descending order beginning 

 with the one nearest the surface, 



1. The first oil sand. — The first oil sand is generally found 

 immediately below the beds of the Yenangyoung stage, at depth 

 varying from about 80 to 100 feet from the surface. Its thickness is 

 never great, being about 20 to 30 feet, but locally it ma) increase 

 somewhat. In the latter case it is very probable that the argilla- 

 ceous bed, which elsewhere separates the first and the second 

 sand, has disappeared, and both form a continuous stratum. Instances 

 will be frequently noticed in the boring registers which indicate this 

 probability. It is remarkable to note that the first oil sand contained 

 only slight traces of oil in two of the northernmost wells, No. 21 

 and A at Kodoung, while in all the other wells it was unpetrolifer- 

 ous, being either dry only containing water. On the other hand it is 

 quite certain that it contained a considerable quantity of petroleum 

 within the Tvvingon and Beme areas, and only quite recently this has 

 been proved by pit wells in the south-western corner of theTwingon 

 area. The oil produced by this sand seems to be the heaviest oil, in- 

 asmuch as its average specific gravity is high<:i: than that of any 

 0? the lower sands. 



2. The second oil sand.— This bed is found at 'a depth of 

 about 150 feet from the surface ; its thickness varies, but it never 

 exceeds 50 feet. As already stated, it is possible that in some parts 

 of the oil field it forms a continuous bed together with the first oil 

 sand. Like the latter it never contained any oil within the limits 

 of the Kodoung tract excepting well No. 40, where a small quantity 



F ( lit ) 



