94 LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



hills separating this part of the plateau from that of the sub-State of 

 Mong Keng, extending towards the Salween. The whole of the central 

 portion of this mass of hills, forming an oval area measuring 11 

 miles from north to south, and 4 from east to west, consists of 

 these purple beds, brought up by a dome-shaped anticlinal. 



The formation here must be of great thickness, for though the 

 hills are deeply eroded, and the beds are tilted up at fairly high 

 angles, no indication of the lower Naungkangyis or any other rocks 

 at the base has been detected. The purple beds are full of crinoid frag- 

 ments, and the detached eyes of trilobites are common enough, but 

 no well preserved fossils were found in this area. 



The purple beds are also exposed along the south-eastern flanks 



{ L ' L' °^ "k* n °' roun d the head of the Nam-Pat 



valley. The thickness exposed here is not 

 so great, either because they are overlapped by higher beds, or 

 perhaps because there was some original thinning out against the 

 platform of older rocks now forming Loi Ling. The purple beds 

 here rest directly upon these older rocks, the lower Naungkangyis 

 being absent or overlapped. 



Among the hills east of Mong Yai, on the western side of the 

 Nam-Ha valley, these beds cover a very wide 



Hills east of Mong Yai. ml " ' . , J . J 



area. Ihe western slopes, from the point 

 where the Tang-Yan cart road crosses the hills north of Mong 

 Yai, to Man-Hpai at the southern end of the range, are almost 

 entirely composed of them, and on the other side of the main 

 ridge they extend from the head of the Nam-Ha river to Mong 

 ^ Heng, where it debouches on to the plateau. 



Fossils abound in the rocks at many places, 

 and outcrops are numerous in the many deep ravines that score 

 the hill sides. Collections were made at about a mile south-west of 

 Hkawnh-kok (Loo. 75, I 3), on the path leading across the hills 

 from Nawa to Man-Hpai, where a species of Asaphus, an Orthis 

 (Dalmavella) and Hyolithes are very common ; at Hwe-hok (Loc. 76, 

 I 3), about half-way between Nawa and Mong-Ha, where fairly 

 well preserved specimens of a species of Ampyx, and a single one 

 of a Trinucleus-\\ke form, probably a Dionide, with the ubiquitous 

 Hyolithes, were obtained ; and in a ravine about half a mile west 

 of Mong-Ha, (Loc. 77, I 3), on the path leading up to the peak 

 marked 6,055 feet. Here the collection included, besides the 

 genera mentioned above, specimens of a Phacops (P(erygometopus) 



