7 8 



NOETLING : PETROLEUM IN BURMA. 



able for a considerable distance. The lowest of these beds, about 

 5 feet thick, is separated from some bluish shales by a bed of white 

 sandstone of 6 to 7 feet in thickness ; it begins quite close at the south- 

 ern end of the ravine, quickly attains its greatest thickness, and then 

 runs as a very regular band, following the general dip towards north, 

 until it disappears. About 30 to 40 feet higher up two other argilla- 

 ceous bands appear, one near the southern, the other towards the 

 northern end of the gully ; both begin as very thin beds, which quickly 

 increase in thickness, but thin out completely further on. A very good 

 instance is however the last bed, which has a maximum thickness of 

 about 20 feet, while for a considerable distance it is reduced to a parting 

 of about 2 inches. It begins as usual as a thin layer, which quickly 

 swells and then thins out, forming a thin, hardly preceptible layer, 

 once more suddenly swelling out to a thickness of about 25 feet; 

 this continues a short distance to die out gradually (see plate IX). 



Another very good illustration of the sudden change of argillaceous 

 to arenaceous beds, within the same level, may be seen at one of 

 the ravines on the western side of the Twingon oil tract, between 

 wells No. 159 and No. 161. 



Fig. 3. Diagrammatic section showing the sudden change from arenaceous to 

 argillaceous beds, between wells 159 and 161. 



As will be seen from this diagram, there is near the right a bed of 

 about 10 to 15 feet of reddish soft sandstone (l) exhibiting two sets of 

 ( 124 ) 



