56 NCETLING: PETROLEUM IN BURMA. 



The plateau conglomerate often forms a hard bank, its parts 

 being firmly bound together by a ferruginous cement ; this appear- 

 ance, together with the frequent occurrence of fossil wood, have 

 frequently induced other observers to include it among the Tertiary 

 system, particularly as ferruginous conglomerates, not nearly so 

 coarse however, are of no infrequent occurrence within the plio- 

 cene division. Its unconformable position on pliocene beds will) 

 however, readily distinguish the plateau conglomerate. 



So far as known to me it chiefly occurs within a certain height 

 above the present level of the river, apparently not exceeding 400 

 feet above sea-level, and generally between 300 and 400 feet. It 

 usually occurs in isolated patches capping the pliocene beds, but 

 more extensive deposits are by no means infrequently found. I 

 am not in a position to state exactly what are the relations between 

 the lower silt and the plateau gravel ; it seems quite evident 

 that the lower silt is overlaid by the plateau gravel, but I also 

 noticed between Kyaukse and Yenangyoung a conglomeratic bed 

 which could not possibly be distinguished from the plateau gravel, 

 interstratified with the lower silt. 



The above outlines of the diluvial strata of Burma do not aim 

 at being exhaustive, and I only mention the subject, since the plateau 

 gravel has been so frequently wrongly identified with the tertiary 

 system. 



B. — The Tertiary system. 



In the neighbourhood of Yenangyoung only the younger tertiaries 

 appear on the surface, but this does not exclude the probability 

 that older tertiaries occur below. 



1.— The Pliocene or Irawadi series. 

 (a) Lithological characters.— The principal rock of the Ira- 

 wadi series is a very soft, friable sandstone, perhaps better termed 

 sand rock. It is generally of light yellowish colour, sometimes almost 

 white. In the lower parts strings of nodular or kidney shaped 

 concretions of hard silicious sandstone are frequently met with ; in 

 ( 102 ) 



