PLIOCENE BEDS. 6l 



to each side are very slight. On the south side of Yenangyaung 

 oil-field the sinking of the anticlinal arch and the consequent decrease 

 of dip is not so rapid as towards the north, and in blocks 13S and 

 14S, eight miles south of Khodaung and the farthest limit of my 

 survey, the dips are still considerable. 



The Irrawaddi (pliocene) beds consist of current-bedded soft 

 ^ L . , sandstones or rather sand rock, which is 



Their characters. ' 



usually so friable that pieces of the rock can be 

 easily broken up between the fingers ; these beds are whitish or 

 yellowish in colour but are in places stained red by iron, and scattered 

 through them are concretions of two kinds. 

 IrraShSl '" the The. larger concretions which are nodular, 

 mammilated or kidney-shaped are siliceous and 

 calcareous ; they are greyish in colour, very hard and often of consi- 

 derable size, two or three feet in diameter or even more, and in the 

 rock they are usually arranged in strings ; besides the nodules there 

 are layers and bands of hard rock which is similar to that forming 

 the nodules. The smaller concretions which are scattered irregularly 

 through the sandstones are calcareous, are rarely more than three or 

 four inches in length, they are whitish or yellowish in colour like the 

 rock in which they are imbedded, of various irregular and fantastic 

 shapes resembling roots of trees, sponges, bones, etc, and often hol- 

 low in the centre. In the lower and upper 



Irregular conglomeritic , ,, . ., • 1 i j r 



bands in the upper and parts of the series there are irregular bands of 



lower parts of the series. . . , r • _ -•• 1 



ferruginous conglomerate of varying thickness, 



most of which when their outcrop is traced are seen to die out within 



a short distance; the bed, however, at the base of the series is fairly 



constant within the area of the Yenangyaung oil-field. Quite 



subordinate to the other beds are some bands and lenticular patches 



of argillaceous beds, clays and sandy- clays, which as a rule do not 



extend far and soon die out, and they are also rarely more than four 



or five feet in thickness. 



The thickness of the Irrawaddi beds it is impossible to tell from 



my last season's work as the top of the series 



Thickness of the beds. , . 1 • i t u i. 



is nowhere to be seen, besides I have not 



( 61 ) 



