STRUCTURE. 47 



Mitchi, the country is covered by recent alluvial beds, which are often 

 of great extent, and the thickness of which it is impossible to tell, 

 but it must be very considerable, as deep stream beds have not 

 reached the base of them. The beds consist of clayey sands, 

 with small nodules of kunkar in places, and gravels with rounded 

 pebbles of quartz and fossil wood. The deposits are, I think, part of 

 an older alluvium of the Irrawaddi. 



The valleys amongst the hills have mostly deposits of stream 

 sands, many of which are of considerable breadth. 



In the beds of several of the streams, and in a few other places 

 where the ground is slightly damp, there is a layer of a white 

 efflorescent salt on the surface of the lower beds of the upper 

 miocene, which when tested proved to be almost entirely composed 

 of sulphate of soda. I am indebted to my colleague Dr. Walker 

 for the following analysis : — 



Na 2 O 34-89 



K a O -24 



Ca O 125 



Mg O i-8o 



CI -32 



SO a 48^09 



Loss on ignition 4*65 



Insoluble . io'oo 



101*24 

 Less Oxygen equivalent *o8 



ioi'i6 



It contains therefore about 78% of N a 2 S0 4 , with smaller 

 quantities of Ca S0 4 and Mg S0 4 . The solution gives a 

 distinctly alkaline reaction with litmus. The origin of this sulphate 

 of soda may possibly be due to the sulphuric acid from the petro- 

 leum bearing beds below. 



Considering now the structure of the country we find that the axis 



of the anticline follows somewhat, but nOt quite, 

 Structure. * ' 



the same up and down course as the heights 

 of the hills ; from Kanthit-kon it gradually rises and reaches a 



( 47 ) 



