52 LA TOUCHE : GEOLOGY OP NORTHERN SHAN STATES. 



usual, by uo means constant. About the latitude of Mong Tung 

 village (H 4), the strike becomes transverse to the general direction 

 of the range, and a change in the character of the rock sets in. 

 The quartzites are replaced by grits and sandstones of quite unalter- 

 ed appearance, on the bedded surfaces of which ripple marks are 

 often visible, and the slates by unaltered yellow shales. But 

 in spite of their unaltered appearance none of these rocks contain 

 a trace of organic remains, and there seems to be no reason for 

 ascribing to them a later age than that of the quartzites and 

 slates. The alteration of the latter indeed seems to be merely a 

 local characteristic, and to be due to the intrusion of large dykes 

 of granite among the rocks at the northern end of the range. 



The sandstones and shales form the whole of the lofty ridge 

 ch f tr<k of Loi Twang, and from a short distance to 

 the south of Mong Tung are found to be 

 striking in a north and south direction, parallel to that of the 

 range. This abrupt change of strike is a feature not easily to be 

 accounted for, but we have seen above that such changes of strike 

 occur elsewhere among these old rocks, and they may be due to 

 distinct and successive periods of earth movements. There is ample 

 evidence that the pre-fossiliferous rocks were folded and dislo- 

 cated, perhaps by forces acting from different directions at successive 

 intervals of time, before the deposition of the overlying strata. The 

 final thrust, which has affected all the rocks of earlier date than 

 the Tertiary, seems to have come from the south-east or perhaps the 

 east, since the direction of the folds and dislocations that have 

 affected the Jurassic Namyau beds is usually from N.-N. E.to S.-S. W. 

 The absence of fossils in the Chaung-Magyi rocks makes any 

 attempt to determine their geological age 



M<4yi«erie S ! he ChaUng ' a matter of uncertainty, as is always the 

 case where stratigraphical position and litbo- 

 logical resemblances are the only guides we can appeal to. As 

 regards their position in the geological sequence we have the fact 

 that these rocks had been deposited, consolidated, thrown into folds 

 and dislocated, and finally subjected to denudation before the ac- 

 cumulation upon them of strata containing Ordovician fossils. No 

 beds containing Cambrian fossils, which would bridge over the 

 interval of time that must have elapsed between these events, have 

 yet been found either in the Shan States or the neighbouring 

 districts nearer than Yunnan ; and it would therefore seem that, 



