60 NOETLING: PETROLEUM IN BURMA. 



species Cyrena (Batissa) crawfurdi, Noetl., and Cyrena {Batissa) 

 petrolei, Noetl. It must also be mentioned that the curious chipped 

 flints, which have been generally recognized as being of artificial 

 origin, have been found in this bed. As I have devoted a special 

 paper to the occurrence of these flints, 1 I need not recapitulate the 

 facts here. 



As regards the horizontal extension of this zone, it may be said 

 that at least in the immediate neighbourhood of the Yenangyoung 

 oil field, it forms a very constant horizon, which disappears towards 

 north below younger beds. In a southern direction, towards 

 Minlindoung, the individuality of this bed becomes less expressed and 

 it seems that it dies out further to the south. If the reality of this 

 horizon be questioned on this ground it must not be forgotten that 

 the bed forms but one of the conglomeratic beds, of so frequent 

 occurrence in the Irawadi division. As at the same time it seemed 

 to be well characterized by the occurrence of certain species, it 

 appeared to me quite admissible to distinguish it as a local horizon, 

 but it cannot now be settled whether it forms a distinct horizon in 

 the Irawadi division. 



I particularly wish to emphasize that the above is but a first 

 attempt to subdivide the pliocene of Burma on a palaeontological 

 basis, which will have to be confirmed by future researches, particu- 

 larly in the Siwalik hills of India. 



2. — The miocene or Pegu series. 

 {ad) The upper miocene or Yenangyoung stage. 

 a. Lilhological characters. — It is chiefly composed of olive 

 coloured clays, always well stratified, and sandstones of the same 

 colour, which usually contain strings of hard concretions of consi- 

 derable size. A good distinguishing feature is found by the pre- 

 sence of gypsum, which occurs in large crystals in the argillace- 

 ous beds. This mineral is so strictly limited to the beds below the 



1 Records, Geological Survey of India, 1894, XXVII, p. 103, and Verhandl. 

 d. Berlin. Anthropol. Gesel., 1894, page 427. 



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