YENANGYOUNG. 55 



the latter, notwithstanding their great Iithological similarity, must of 

 course be of much later date than the pliocene strata. 



I had no time to spare to examine the lower silt in detail, but 

 it does not seem to contain fossils. 



(2) The plateau gravel. — Almost everywhere in the central part 

 of Burma, the pliocene beds are covered by a bed of coarse gravel 

 of varying thickness. The gravel consists chiefly of well rolled, large 

 pebbles of white cellular quartz, rolled fragments of silicified wood, 

 and sometimes rolled fragments of fossil bones. Judging from the 

 latter it seems evident, that the plateau gravel has been largely 

 derived from the eroded pliocene beds, but to what parts and in 

 what direction we have to look for the origin of the quartz pebbles 

 remains an unsolved problem for the present. There are conglomera- 

 tic beds in the lower part of the Prome beds in the Chindwin 

 country, but it is doubtful whether the large pebbles in the neigh- 

 bourhood of Yenangyoung could be derived from them. 



The most astonishing fact is the size of these quartz pebbles, 

 which are as large as a man's fist, and sometimes still larger. Pebbles of 

 this size cannot have been transported to their present locality from the 

 Shan hills, or the country north of Bhamo where metamorphic rocks 

 occur. In this case the drainage of the country must have undergone 

 considerable changes since these pebbles were deposited • at present 

 the Irawadi forms only sand banks of the finest sand or silt not only 

 in this part of the country, but also higher up its course. How, there- 

 fore, these quartz pebbles could have been transported to their pre- 

 sent resting place, when their size proves that they could not have been 

 transported a very long distance, and within a long distance there are 

 no older strata containing such quartz pebbles, from which they could 

 have been possibly derived, remains at present a problem which I am 

 unable to solve. I may mention that the presence of these pebbles 

 could not be explained as of glacial origin ; so far as known 

 to me, there are not the slightest traces of glacial conditions either 

 in the past or present to be found in Burma. 



( 'CI ) 



