6 



LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



more than small parts of the sinking blocks which have become jammed. 

 Sometimes they still touch both sides of the valley, forming a kind of bar or ridge. 

 Such bars, breaking seemingly the continuity of the valley, are numerous and of 

 smaller or larger extension, and they account also in some degree for the direction 

 of the drainage. A most perfect instance of such a bar may be seen between 

 the villages of Manpeng and Meungyaw. Here the bar has a length of about 5 

 miles ; the breadth may be about the same. The bar consists of red sandstone, 

 resting on blue limestone, while the hills on both sides are formed of blue lime- 

 stone. Thus tha lateral boundary between red sandstone and blue limestone 

 is as distinct as possible, proving plainly the existence of a fault on either 

 side of the bar. Similar bars may be seen east and west of Lashio, but I have 

 never noticed them so clearly discernible as in the instance quoted above." 



With the exception of the short stretch of the Nam-Tu valley 

 between Namhsim and Hsipaw (F 2), where a large block of red 

 sandstones is let down by parallel faults, one bounding the river 

 valley on the north, and the other passing through Loimawk, on 

 the southern side of the hills south of Bawgyo, the existence of 

 two systems of parallel faults extending the whole length of the 

 Nam-Tu and Namyau valleys north-eastwards from Hsipaw has 

 been found to be purely imaginary. The so-called ' bar ' extend- 

 ing across the valley of the Namyau below Mong-yaw is not a 

 portion of the red sandstones jammed between two lateral faults, 

 but is a continuation of the band which arises immediately to 

 the east of Lashio, and may be traced far to the north-east across 

 the Namyau valley, flanked by the ' blue limestone ' in parallel 

 sequence on either side. In fact, from the Salween to Hsipaw, the 

 structure is an ordinary succession of folds, striking from north- 

 east to south-west, across which the rivers have cut their valleys 

 more or less diagonally. Only one fault of importance has been 

 noticed in this part of the river course, viz., at Manlong-Mansang, 

 and this crosses the river almost at right angles. There certainly are 

 peculiarities in the drainage system of the plateau, but they seem 

 to be due to the capture by the Nam-Tu, which now drains prac- 

 tically the whole area, of the waters that once perhaps flowed 

 eastwards into the Salween. 



Dr. Noetling classifies the formations met with by him accord- 

 Dr. Noetling's classifi- hig to the following list, in descending order:— 



cation. 



6. Alluvial formation, including river deposits and hill clay. 

 5. Tertiary formation, probably younger miocene. 

 4. Red sandstones of undetermined age. 



