GEOLOGY. 179 



is geological work in the remainder on account of its uninhabited 



and trackless nature and the thick mantle of forest and soil. 



The general strike of the Mergui Series is north-north-west- 

 south- south-east, the same direction as the 

 trend of the mountain ranges and the longer 

 axes of the granite intrusions : this is also the most usual strike 

 of the wolfram-bearing quartz veins. Locally the strike may 

 vary from north-south to north-west-south-east. 



The dip, where it can be seen, is always high, from 60° to vertical, 



and is very irregular. The tectonic structure 



*' of the district cannot be made out, but it is 



probable that the Mergui Scries is repeated several times in an east 



to west section, in closely pressed folds. 



For the above noted reasons, faulting cannot be traced except 

 in a few of the larger mines where surveys 

 are kept. In these, unfortunately for mining 

 operations, small strike faults arc found to be very numerous in 

 both sedimentaries and granite, but data are as yet insufficient 

 to warrant general conclusions. In the granite of the Taungdaw 

 intrusion several horizontal faults occur, but not so far as is known 

 in the sedimentaries, where however underground mining is not 

 nearly so extensive. 



None of these faults are of structural importance as far as is 

 known at present, their throws being in the neighbourhood of a 

 hundred feet as a maximum There is a possibility that a large 

 fault runs through the Heinze Basin, but no direct evidence of its 

 presence has been obtained ; the conjecture is tentatively advanced 

 in view of the marked subsidence which has taken place in the 

 Basin, the disturbance of the rocks underlying the Kanbauk valley 

 (which however may be otherwise explained), and the remark- 

 ably flat lie of the veins on three concessions near Kanbauk — Medaw 

 Kambay (Meinmadaung on the map), Taungshuntaung (near Taung- 

 yinin) and Pachaung. These three localities are on a straight line, 

 parallel to the general strike and corresponding roughly to the 

 long axis of the Heinze Basin. They are the only mines, with the 

 exception of lleinda, where veins with low dips are the general rule. 

 The ultimate weathered product of the sedimentaries is 

 a brownish-red clayey soil which covers all 

 Wcathcrmg. the hillsides except vv } icre gl . a nite is the under- 



lying rock. The conditions favouring atmospheric alteration are 



