YENANGYOUNG. 95 



(g) In all wells in which the drill passed through the third oil- 

 sand, a bed of clay has been found immediately underneath it, which 

 lithologically does not differ from any of the other clay beds. 



(h) Below the above layer of clay occurs a thick stratum of arenace- 

 ous beds which forms the fourth oil-sand. It has been found in wells 

 Nos. 40, 13, 51, 54 and 57. This sand does not always contain 

 petroleum ; in some instances like No. 54 it is water bearing at the 

 top, dry in the middle and petroliferous at the base, it is apparently 

 divided by some minor parting of clay in No. 51, while it is almost 

 certain that it forms a continuous layer together with the third oil- 

 sand in wells Nos. 59 and 60. 



(i) There are only a few wells which have passed through the 

 4th sand, but there are proofs that it is followed by a comparatively 

 thin bed of bluish clay. 



Below this bed follows in well No. 54 a series of sandy layers 

 one of which is petroliferous (k), separated by argillaceous partings. 

 Whether these strata represent proper horizons, or whether we have 

 to consider the series as a thick argillaceous bed subdivided by 

 sandy layers, remains to be seen. 



I have constructed the sections on plate XII, with reference to the 

 above remarks about the sequence of the beds found in the petroli- 

 ferous series. How far my views expressed in this way are correct 

 remains to be seen. It is quite possible that, owing to the great 

 similarity of the lithological character of the beds, errors have not 

 been avoided in the correlation of some of the beds, but I believe that 

 the main outlines of the sequence will be found to be correct. 



As the wells are never situated in exactly straight lines, I have 

 drawn across the area of the Kodoung field a series of transverse 

 lines, connecting the greatest number of wells by a straight line, 

 whilst others which did not exactly come within this line were 

 included when they were not too far off. In this manner I obtained 

 a series of cross sections which are shown on plate XII. A com- 

 parison of these transverse sections with each other, shows how 

 hopeless it is to unravel the detailed structure of the Yenangyoung 



( Mi ) 



