350 LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



and the equally well marked affinities of the latter with the faunas 

 of northern Europe. Even in Permo-Carboniferous times it does 

 not appear to be necessary to suppose that this barrier was sub- 

 merged, as I shall attempt to show later on ; and indeed it is 

 possible that, in common with the rocks of the greater part of the 

 Indian Peninsula, this tract has never been submerged beneath the 

 sea, since the pre-Cambrian era. Wedged in between the fields of 

 action of two of the principal lines of thrust, one from the north and 

 the other from the east, it appears to have retained its position during 

 the whole course of geological history. The existence of a per- 

 manent land area to the north of Burma would also, I think, ac- 

 _ , count for the peculiar features exhibited by 



Course of the balween. , A 



the course 01 the fealween. Jbor it that river 

 is, as I have suggested, of earlier origin than the Mekhong and the 

 Irrawaddy, as the comparative depth of its valley seems to indicate, 

 it may be comparable in antiquity with the larger rivers of the 

 Indian Peninsula ; and if so, continental conditions must have pre- 

 vailed along its course for an immensely long period of time. 

 The Mekhong, the Irrawaddy with its tributaries, the Myitnge and 

 the Shweli, and the real Brahmaputra, that is to say the portion 

 of it which lies above Sadiya in Assam, are busily engaged in cut- 

 ting back into the old land, and have deprived the Salween of most 

 of its tributaries. And the reason that it still survives as an in- 

 dependent river is that these more modern rivers have not yet been 

 able to cut down to its level or succeeded in ' beheading ' it. 



Turning to the south-east and south we are even more ignorant 



of the trend of the Ordovician coast line, for 

 Southern extension of . th&t directj g0 far as j am awar nQ 

 coast line. m m ' 



fossiliferous rocks of earlier age than the 

 Plateau Limestone are known to occur, until we reach Australia, 

 which, it is well known, formed a part of the Gondwana continent : 

 but it probably coincided more or less closely with the line of the 

 Malay Peninsula and of the Archipelago. 



In Ordovician times then we may suppose that the sediments 

 were deposited in a tranquil and rather shallow 



Emergence in Silurian ^ &n uneven fl d thege CQndi _ 



times. ' ' . 



tions seem to have lasted until the Namhsim 



stage. At this time there may have been an emergence of the 



coast line to the north, causing an influx of sandy sediment. For 



these sandstones are confined to the northern portion of cur area 



